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Pra AD, Lyness J, Pollack A, Tran PT, Koontz BF, Abramowitz MC, Mahal BA, Martin AG, Michalski JM, Balogh A, Lukka H, Faria SL, Rodrigues G, Beauchemin MC, Lee RJ, Seaward SA, Coen SD, Allen AM, Pugh S, Feng FY. Impact of Testosterone Recovery on Clinical Outcomes of Patients Treated with Salvage Radiotherapy and Androgen Suppression: A Secondary Analysis of the NRG/RTOG 0534 Sport Phase 3 Trial. Int J Radiat Oncol Biol Phys 2023; 117:S82-S83. [PMID: 37784585 DOI: 10.1016/j.ijrobp.2023.06.403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Testosterone (T) kinetics and its relationship with clinical outcomes has not been studied in trials using salvage radiotherapy and androgen deprivation therapy (ADT). We performed a secondary analysis of the NRG Oncology/RTOG 0534 SPPORT trial, which compared prostate bed radiotherapy (PBRT) (arm 1), PBRT + short-term androgen deprivation therapy (ADT) (arm 2), or PBRT + pelvic lymph node radiotherapy (PLNRT) + short-term ADT (arm 3). We assessed longitudinal serum T levels and the impact of testosterone recovery (TR) on clinical outcomes. MATERIALS/METHODS ADT was given for 4-6 months in arms 2 and 3, starting 2 months prior to radiotherapy. The trial excluded patients with baseline T < 40% of the lower limit of normal. TR was defined in 3 ways: 1) return to non-castrate level (>50 ng/dL), 2) return to normal level (>300 ng/dL), and 3) return to baseline level. Time to TR was estimated using cumulative incidence and death without an event considered a competing risk. Unadjusted and adjusted hazard ratios and 95% confidence intervals (CIs) were calculated using Cox proportional hazards model. Freedom from progression (FFP) was defined as biochemical failure according to the Phoenix definition (PSA ≥2 ng/mL over the nadir PSA), clinical failure (local, regional, or distant), or death from any cause. RESULTS A total of 1699 patients with T at baseline and at least 1 follow-up assessment were included. The median age was 64 years (IQR 59 - 69), 12.8% were black, 14.9% had diabetes, and 54.1% were former or current smokers. Median baseline T in arms 1, 2 and 3 was 320 ng/dL (IQR 239 - 424), 319 ng/dL (IQR 237 - 438) and 330 ng/dL (IQR 252 - 446), respectively. At 6 months, median T in arms 1, 2 and 3 was 290 ng/dL (IQR 210 - 390), 190.4 ng/dL (IQR 66 - 296) and 191 ng/dL (IQR 40.5 - 313). At 2 years, in arms 2 and 3, TR to non-castrate, normal and baseline levels were 95%, 55% and 23%, respectively. At 5 years, in arms 2 and 3, TR to non-castrate, normal and baseline levels were 98%, 73% and 42%, respectively. FFP was superior in arms 2 and 3 vs. arm 1 in patients with TR by all three definitions. In patients with recovered T to normal levels by 2 years (n = 904), the 5-year FFP rates were 71.8% (95% CI 66.9-76.6) in arm 1, 77.2% (72.1-82.2) in arm 2, and 86.3% (82.3-90.3) in arm 3 (arm 2 vs arm 1: HR 0.74, 95% CI 0.56-0.98, p = 0.034; arm 3 vs arm 1: HR 0.54, 95% CI 0.40-0.72, p<.0001). CONCLUSION This work represents the largest study of T kinetics in patients treated with salvage radiation and ADT. Approximately half of patients did not normalize their T levels by 2 years. Our data validate an incremental and meaningful FFP benefit of adding short-term ADT and PLNRT to PBRT independent of T recovery.
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Affiliation(s)
- A Dal Pra
- Department of Radiation Oncology, University of Miami/Sylvester Comprehensive Cancer Center, Miami, FL
| | - J Lyness
- NRG Oncology Statistics and Data Management Center, Philadelphia, PA
| | - A Pollack
- Department of Radiation Oncology, University of Miami/Sylvester Comprehensive Cancer Center, Miami, FL
| | - P T Tran
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD
| | | | - M C Abramowitz
- Department of Radiation Oncology, University of Miami/Sylvester Comprehensive Cancer Center, Miami, FL
| | - B A Mahal
- Department of Radiation Oncology, University of Miami/Sylvester Comprehensive Cancer Center, Miami, FL
| | - A G Martin
- Department of Radiation Oncology CHU de Québec-Université Laval, Québec, QC, Canada
| | - J M Michalski
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO
| | - A Balogh
- Tom Baker Cancer Centre, Calgary, AB, Canada
| | - H Lukka
- Juravinski Cancer Centre, Hamilton, ON, Canada
| | - S L Faria
- McGill University Health Centre, Montreal, QC, Canada
| | - G Rodrigues
- London Health Sciences Centre, London, ON, Canada
| | - M C Beauchemin
- Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada
| | - R J Lee
- Intermountain Medical Center, Murray, UT
| | | | - S D Coen
- Southeast Clinical Oncology Research Consortium, Winston Salem, NC
| | - A M Allen
- Rabin Medical Center - Beilinson Hospital, Petah Tickva, Israel
| | - S Pugh
- NRG Oncology Statistics and Data Management Center, Philadelphia, PA
| | - F Y Feng
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA
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Driver R, Allen AM, Finneran S, Maksut JL, Eaton LA, Kalichman SC. Masculine ideology and Black men who have sex with men's interest in HIV pre-exposure prophylaxis (PrEP). J Health Psychol 2020; 26:2908-2920. [PMID: 32638629 DOI: 10.1177/1359105320941236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We examined how traditional masculinity and stigma surrounding HIV pre-exposure prophylaxis (PrEP) affect PrEP interest among Black men who have sex with men (BMSM). One hundred twenty-three men attending a Black Gay Pride event completed measures assessing traditional masculinity, PrEP stigma, and PrEP interest along with two behavioral measures of interest in PrEP. Results demonstrated that avoidance of femininity directly related to interest in PrEP and indirectly through conformity to heterosexual self-presentation. Further, PrEP stigma differentially moderated both of these relationships. Interventions designed to improve engagement of PrEP for BMSM should be attentive to traditional masculinity as a barrier.
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Camacho G, Allen AM, Quinn DM. Neighborhood Ethnic Composition and Perceived Discrimination Among Young Adult Latina/os: The Mediating Role of Ethnic Centrality. Hispanic Journal of Behavioral Sciences 2019. [DOI: 10.1177/0739986319851248] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study examines whether neighborhood ethnic composition (i.e., percentage of Latina/os residing in a given residential community) predicts greater perceived experiences of ethnic discrimination and whether this direct effect is mediated by ethnic centrality (i.e., perceived importance of ethnicity for one’s identity). In a cross-sectional study, 237 self-identified young adult Latina/os reported their five-digit zip codes and sociodemographic information and completed measures of ethnic centrality and perceived ethnic discrimination. A mediation analysis revealed that neighborhood ethnic composition indirectly predicted perceived ethnic discrimination through its effect on ethnic centrality even when accounting for known sociodemographic predictors of perceived discrimination, b = 0.28, SE = .18, 95% confidence interval (CI) = [0.03, 0.71]. These results provide initial evidence that where young adult Latina/os live and grow up impacts the extent to which they find their ethnicity to be an essential part of their identity and, consequently, their perceived frequency of experiencing ethnic discrimination.
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Earnshaw VA, Reed NM, Watson RJ, Maksut JL, Allen AM, Eaton LA. Intersectional internalized stigma among Black gay and bisexual men: A longitudinal analysis spanning HIV/sexually transmitted infection diagnosis. J Health Psychol 2019; 26:465-476. [PMID: 30599761 DOI: 10.1177/1359105318820101] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Internalized stigma undermines health among people diagnosed with HIV and other sexually transmitted infections (STI), yet limited research has examined how internalized stigma develops. Black gay and bisexual men (n = 151) reported their race and sexual orientation internalized stigma once before HIV/STI diagnosis and their HIV/STI internalized stigma monthly for 1 year after HIV/STI diagnosis. Multilevel analyses demonstrated that race and sexual orientation internalized stigma before diagnosis were associated with greater HIV/STI internalized stigma after diagnosis. More research is needed to understand how internalized stigma develops, including within the context of other identities and broader environmental characteristics to inform intervention efforts.
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Allen AM, Leach CW. The Psychology of Martin Luther King Jr.'s "Creative Maladjustment" at Societal Injustice and Oppression. J Soc Issues 2018; 74:317-336. [PMID: 36090742 PMCID: PMC9462883 DOI: 10.1111/josi.12271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Many theoretical frameworks in psychology are premised on the notion that people are hedonistic in nature-drawn to pleasure and avoidant of discomfort. In this essay, we argue that psychology's hedonism contrasts with Martin Luther King Jr's conception of creative maladjustment, wherein a feeling of "cosmic discontent" is focused on the ugly truth of societal injustice. After reviewing hedonistic assumptions in the psychology of coping, well-being, and views of societal inequality, we discuss MLK's conception of creative maladjustment and tie it to critical consciousness and the present-day idea of being "woke." We then use MLK's ideas as a lens on contemporary psychological research of views of societal injustice "from above" and "from below." We suggest that MLK's analysis continues to challenge psychology to develop an approach to cognition, emotion, and motivation at societal injustice that identifies the ethical value of a sustained discontent that illuminates truth and animates opposition.
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Affiliation(s)
- Aerielle M. Allen
- Correspondence concerning this article should be addressed to A.M. Allen, Department of Psychological Sciences, University of Connecticut, Storrs, CT 06521-1020 [ or ]
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Carter DA, Guo H, Connelly AA, Bassi JK, Fong AY, Allen AM, McDougall SJ. Viscerosensory input drives angiotensin II type 1A receptor-expressing neurons in the solitary tract nucleus. Am J Physiol Regul Integr Comp Physiol 2017; 314:R282-R293. [PMID: 29118020 DOI: 10.1152/ajpregu.00290.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Homeostatic regulation of visceral organ function requires integrated processing of neural and neurohormonal sensory signals. The nucleus of the solitary tract (NTS) is the primary sensory nucleus for cranial visceral sensory afferents. Angiotensin II (ANG II) is known to modulate peripheral visceral reflexes, in part, by activating ANG II type 1A receptors (AT1AR) in the NTS. AT1AR-expressing NTS neurons occur throughout the NTS with a defined subnuclear distribution, and most of these neurons are depolarized by ANG II. In this study we determined whether AT1AR-expressing NTS neurons receive direct visceral sensory input, and whether this input is modulated by ANG II. Using AT1AR-GFP mice to make targeted whole cell recordings from AT1AR-expressing NTS neurons, we demonstrate that two-thirds (37 of 56) of AT1AR-expressing neurons receive direct excitatory, visceral sensory input. In half of the neurons tested (4 of 8) the excitatory visceral sensory input was significantly reduced by application of the transient receptor potential vallinoid type 1 receptor agonist, capsaicin, indicating AT1AR-expressing neurons can receive either C- or A-fiber-mediated input. Application of ANG II to a subset of second-order AT1AR-expressing neurons did not affect spontaneous, evoked, or asynchronous glutamate release from visceral sensory afferents. Thus it is unlikely that AT1AR-expressing viscerosensory neurons terminate on AT1AR-expressing NTS neurons. Our data suggest that ANG II is likely to modulate multiple visceral sensory modalities by altering the excitability of second-order AT1AR-expressing NTS neurons.
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Affiliation(s)
- D A Carter
- Department of Physiology, The University of Melbourne , Victoria , Australia
| | - H Guo
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne , Victoria , Australia
| | - A A Connelly
- Department of Physiology, The University of Melbourne , Victoria , Australia
| | - J K Bassi
- Department of Physiology, The University of Melbourne , Victoria , Australia
| | - A Y Fong
- Department of Physiology, The University of Melbourne , Victoria , Australia
| | - A M Allen
- Department of Physiology, The University of Melbourne , Victoria , Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne , Victoria , Australia
| | - S J McDougall
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne , Victoria , Australia
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Carter DA, Choong YT, Connelly AA, Bassi JK, Hunter NO, Thongsepee N, Llewellyn-Smith IJ, Fong AY, McDougall SJ, Allen AM. Functional and neurochemical characterization of angiotensin type 1A receptor-expressing neurons in the nucleus of the solitary tract of the mouse. Am J Physiol Regul Integr Comp Physiol 2017; 313:R438-R449. [PMID: 28701322 DOI: 10.1152/ajpregu.00168.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 11/22/2022]
Abstract
Angiotensin II acts via two main receptors within the central nervous system, with the type 1A receptor (AT1AR) most widely expressed in adult neurons. Activation of the AT1R in the nucleus of the solitary tract (NTS), the principal nucleus receiving central synapses of viscerosensory afferents, modulates cardiovascular reflexes. Expression of the AT1R occurs in high density within the NTS of most mammals, including humans, but the fundamental electrophysiological and neurochemical characteristics of the AT1AR-expressing NTS neurons are not known. To address this, we have used a transgenic mouse, in which the AT1AR promoter drives expression of green fluorescent protein (GFP). Approximately one-third of AT1AR-expressing neurons express the catecholamine-synthetic enzyme tyrosine hydroxylase (TH), and a subpopulation of these stained for the transcription factor paired-like homeobox 2b (Phox2b). A third group, comprising approximately two-thirds of the AT1AR-expressing NTS neurons, showed Phox2b immunoreactivity alone. A fourth group in the ventral subnucleus expressed neither TH nor Phox2b. In whole cell recordings from slices in vitro, AT1AR-GFP neurons exhibited voltage-activated potassium currents, including the transient outward current and the M-type potassium current. In two different mouse strains, both AT1AR-GFP neurons and TH-GFP neurons showed similar AT1AR-mediated depolarizing responses to superfusion with angiotensin II. These data provide a comprehensive description of AT1AR-expressing neurons in the NTS and increase our understanding of the complex actions of this neuropeptide in the modulation of viscerosensory processing.
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Affiliation(s)
- D A Carter
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Y-T Choong
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - A A Connelly
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - J K Bassi
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - N O Hunter
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - N Thongsepee
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - I J Llewellyn-Smith
- Cardiovascular Medicine and Human Physiology, School of Medicine, Flinders University, Bedford Park, South Australia, Australia; and
| | - A Y Fong
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - S J McDougall
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - A M Allen
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, Australia; .,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
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Pellowski JA, Price DM, Allen AM, Eaton LA, Kalichman SC. The differences between medical trust and mistrust and their respective influences on medication beliefs and ART adherence among African-Americans living with HIV. Psychol Health 2017; 32:1127-1139. [PMID: 28475365 DOI: 10.1080/08870446.2017.1324969] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The purpose of this study was to examine the relationships between medical mistrust and trust and to determine if these measures differentially predict antiretroviral therapy (ART) medication adherence for African-American adults living with HIV. DESIGN A total of 458 HIV positive African-Americans completed a cross-sectional survey. MAIN OUTCOME MEASURES Self-reported ART adherence was collected using the visual-analog scale. The Beliefs About Medicines Questionnaire was used to assess medication necessity and concern beliefs. RESULTS All measures of medical mistrust and trust were significantly negatively correlated, ranging from r = -.339 to -.504. Race-based medical mistrust significantly predicted medication necessity and concern beliefs, whereas general medical mistrust only significantly predicted medication concerns. Both measures of trust significantly predicted medication necessity beliefs and medication concerns. Higher levels of race-based medical mistrust predicted lower medication adherence, whereas, neither trust in own physician nor trust in health care provider significantly predicted medication adherence. However, trust in own physician significantly predicted medication necessity beliefs, which predicted medication adherence. CONCLUSION Trust and mistrust are not simply opposites of one another. These findings provide evidence for the complexity of understanding the relationship between health care trust, mistrust and patient-related health beliefs and behaviours.
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Affiliation(s)
- Jennifer A Pellowski
- a Department of Psychiatry and Human Behavior , Alpert Medical School of Brown University , Providence , RI , USA
| | - Devon M Price
- b Department of Psychology , University of Connecticut , Storrs , CT , USA
| | - Aerielle M Allen
- b Department of Psychology , University of Connecticut , Storrs , CT , USA
| | - Lisa A Eaton
- c Department of Human Development and Family Sturdies , University of Connecticut , Storrs , CT , USA
| | - Seth C Kalichman
- b Department of Psychology , University of Connecticut , Storrs , CT , USA
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Menuet C, Wlodek ME, Fong AY, Allen AM. Respiratory modulation of sympathetic nerve activity is enhanced in male rat offspring following uteroplacental insufficiency. Respir Physiol Neurobiol 2015; 226:147-51. [PMID: 26593642 DOI: 10.1016/j.resp.2015.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/22/2015] [Accepted: 11/12/2015] [Indexed: 11/25/2022]
Abstract
Sympathetic nerve activity to the cardiovascular system displays prominent respiratory-related modulation which leads to the generation of rhythmic oscillations in blood pressure called Traube-Hering waves. An amplification of this respiratory modulation of sympathetic activity is observed in hypertension of both genetic, the spontaneously hypertensive rat, and induced, chronic intermittent hypoxia or maternal protein restriction during gestation, origin. Male offspring of mothers with uteroplacental insufficiency, induced by bilateral uterine vessel ligation at 18 days of gestation, are also hypertensive in adulthood. In this study we examined whether these male offspring display altered respiratory modulation of sympathetic activity at pre-hypertensive ages compared to controls. Respiratory, cardiovascular and sympathetic parameters were examined using the working heart-brainstem preparation in 35 day old male rats that had reduced birth weight due to uteroplacental insufficiency. Whilst all respiratory parameters were not different between groups, we observed an enhanced respiratory-related burst of thoracic sympathetic nerve activity and amplified Traube-Hering waves in the growth-restricted group. This group also showed an increased sympathetic and bradycardic response to activation of peripheral chemoreceptors. The observations add support to the view that altered respiratory modulation of sympathetic activity represents a common mechanism involved in the development of several forms of hypertension.
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Affiliation(s)
- C Menuet
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia.
| | - M E Wlodek
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
| | - A Y Fong
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
| | - A M Allen
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
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Allen AM, Hay JE. Review article: the management of cirrhosis in women. Aliment Pharmacol Ther 2014; 40:1146-54. [PMID: 25263269 DOI: 10.1111/apt.12974] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 07/21/2014] [Accepted: 09/09/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND There are differences in the predisposition, natural history of liver disease, complications and treatment response between men and women. AIM To review clinical differences in cirrhosis between men and women and to address unique management issues of fertility, pregnancy and contraception in this patient population. METHODS PubMed and MEDLINE were searched using the terms 'cirrhosis' and 'chronic liver disease', each cross-referenced with specific liver diseases, as well as terms such as 'cancer', 'hepatocellular carcinoma', 'smoking', 'liver transplantation', 'metabolic bone disease', 'fertility',' pregnancy' and 'contraception'. RESULTS Pre-menopausal status is protective in viral hepatitis C and non-alcoholic steatohepatitis. However, smoking, especially in combination with alcohol, is a stronger risk factor for cirrhosis and malignancies in women with chronic liver disease compared to men, although they are less likely than men to develop hepatocellular carcinoma. Women with cirrhosis have more osteopenic bone disease than men and require active management. Successful pregnancy is possible in well-compensated cirrhosis or with mild portal hypertension, although the maternal and foetal mortality and morbidity are higher than in the general population. The maternal risk correlates with liver disease severity and derives mostly from variceal bleeding. The choices for contraception in compensated cirrhosis are generally the same as for the general population. Women with cirrhosis are disadvantaged by the current MELD system of organ allocation, at least in part due to body size. CONCLUSION The management of women with chronic liver disease is unique in regards to counselling, screening for complications, fertility and pregnancy.
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Affiliation(s)
- A M Allen
- Hepatology and Liver Transplantation, Mayo Clinic, Rochester, MN, USA
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Allen AM, Kim WR, Xiong H, Liu J, Stock PG, Lake JR, Chinnakotla S, Snyder JJ, Israni AK, Kasiske BL. Survival of recipients of livers from donation after circulatory death who are relisted and undergo retransplant for graft failure. Am J Transplant 2014; 14:1120-8. [PMID: 24731165 PMCID: PMC4546823 DOI: 10.1111/ajt.12700] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 12/13/2013] [Accepted: 12/22/2013] [Indexed: 01/25/2023]
Abstract
Use of grafts from donation after circulatory death (DCD) as a strategy to increase the pool of transplantable livers has been limited due to poorer recipient outcomes compared with donation after brain death (DBD). We examined outcomes of recipients of failed DCD grafts who were selected for relisting with regard to waitlist mortality and patient and graft survival after retransplant. From the Scientific Registry of Transplant Recipients database, we identified 1820 adults who underwent first deceased donor liver transplant January 1, 2004 to June 30, 2011, and were relisted due to graft failure; 12.7% were DCD recipients. Compared with DBD recipients, DCD recipients had better waitlist survival (90-day mortality: 8%, DCD recipients; 14-21%, DBD recipients). Of 950 retransplant patients, 14.5% were prior DCD recipients. Graft survival after second liver transplant was similar for prior DCD (28% graft failure within 1 year) and DBD recipients (30%). Patient survival was slightly better for prior DCD (25% death within 1 year) than DBD recipients (28%). Despite higher overall graft failure and morbidity rates, survival of prior DCD recipients who were selected for relisting and retransplant was not worse than survival of DBD recipients.
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Affiliation(s)
- AM Allen
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - WR Kim
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota,Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota
| | - H Xiong
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota
| | - J Liu
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota
| | - PG Stock
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota,Department of Surgery, University of California, San Francisco, California
| | - JR Lake
- Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Minnesota, Minneapolis, Minnesota
| | - S Chinnakotla
- Department of Surgery, University of Minnesota, Minneapolis, Minnesota
| | - JJ Snyder
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota,Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota
| | - AK Israni
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota,Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota,Department of Medicine, Hennepin County Medical Center, University of Minnesota, Minneapolis, Minnesota
| | - BL Kasiske
- Scientific Registry of Transplant Recipients, Minneapolis Medical Research Foundation, Minneapolis, Minnesota,Department of Medicine, Hennepin County Medical Center, University of Minnesota, Minneapolis, Minnesota
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Allen AM, O'Callaghan EL, Hazelwood L, Germain S, Castrop H, Schnermann J, Bassi JK. Distribution of cells expressing human renin-promoter activity in the brain of a transgenic mouse. Brain Res 2008; 1243:78-85. [PMID: 18840419 DOI: 10.1016/j.brainres.2008.09.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 09/12/2008] [Accepted: 09/13/2008] [Indexed: 10/21/2022]
Abstract
Renin plays a critical role in fluid and electrolyte homeostasis by cleaving angiotensinogen to produce Ang peptides. Whilst it has been demonstrated that renin mRNA is expressed in the brain, the distribution of cells responsible for this expression remains uncertain. We have used a transgenic mouse approach in an attempt to address this question. A transgenic mouse, in which a 12.2 kb fragment of the human renin promoter was used to drive expression of Cre-recombinase, was crossed with the ROSA26-lac Z reporter mouse strain. Cre-recombinase mediated excision of the floxed stop cassette resulted in expression of the reporter protein, beta-galactosidase. This study describes the distribution of beta-galactosidase in the brain of the crossed transgenic mouse. In all cases where it was examined the reporter protein was co-localized with the neuronal marker NeuN. An extensive distribution was observed with numerous cells labeled in the somatosensory, insular, piriform and retrosplenial cortices. The motor cortex was devoid of labeled cells. Several other regions were labeled including the parts of the amygdala, periaqueductal gray, lateral parabrachial nucleus and deep cerebellar nuclei. Overall the distribution shows little overlap with those regions that are known to express receptors for the renin-angiotensin system in the adult brain. This transgenic approach, which demonstrates the distribution of cells which have activated the human renin promoter at any time throughout development, yields a unique and extensive distribution of putative renin-expressing neurons. Our observations suggest that renin may have broader actions in the brain and may indicate a potential for interaction with the (pro)renin receptor or production of a ligand for non-AT(1)/AT(2) receptors.
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Affiliation(s)
- A M Allen
- Department of Physiology, The University of Melbourne, Melbourne, Victoria, 3010, Australia.
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Ionascu D, Park SJ, Killoran JH, Allen AM, Berbeco RI. TU-C-351-08: Application of Principal Component Analysis for Marker-Less Lung Tumor Tracking with Beam's-Eye-View EPID Images. Med Phys 2008. [DOI: 10.1118/1.2962477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Oldfield BJ, Allen AM, Davern P, Giles ME, Owens NC. Lateral hypothalamic 'command neurons' with axonal projections to regions involved in both feeding and thermogenesis. Eur J Neurosci 2007; 25:2404-12. [PMID: 17445237 DOI: 10.1111/j.1460-9568.2007.05429.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The concept of 'command neurons', whereby single neurons mediate complex and complementary motor functions to generate a stereotyped behaviour, is well developed in invertebrate physiology. The term has also been adopted more recently to explain the neural basis of 'fight or flight'. In this study we have investigated the possibility that single lateral hypothalamic neurons have the necessary neuroanatomical connections to coordinate two complementary limbs of body weight control, feeding and thermogenesis, thereby acting as 'command neurons'. The transynaptic retrograde transport of pseudorabies virus (Bartha) from a thermogenic endpoint in the brown adipose tissue of rats has been used in conjunction with other neuronal tracers, introduced into putative CNS feeding centres, to assess the potential for the involvement of command neurons in coordinating these processes. In discrete regions of the lateral hypothalamus, neurons have been identified which have the necessary complement of orexigenic peptides and collateral branching axons to both putative feeding sites and thermogenic sites in brown fat to qualify as candidate central command neurons controlling body weight.
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Affiliation(s)
- B J Oldfield
- Department of Physiology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
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15
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Abstract
Complement-fixing (CF) antibody to Bacillus piliformis antigen was found in 9 of 14 (64%) serum samples obtained from cottontail rabbits (Sylvilagus floridanus) killed in the wild. CF antibody was not present in the serum of 8 cottontail rabbits trapped as juveniles in the same geographic areas and held in captivity for 4 years. Sero-negative cottontail rabbits died acutely with lesions typical of Tyzzer's disease following the intragastric administration of 10(3.8) ELD50 of B. piliformis spores. The possible influence of Tyzzer's disease upon the cyclic population pattern of cottontail rabbits in the wild is discussed. A hypothesis is presented that B. piliformis spores passed in the feces of diseased wild animals could contaminate pastures, hay and grain, and thereby serve as sources of infection to other animals.
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Affiliation(s)
- J R Ganaway
- Comparative Pathology Section, Veterinary Resources Branch, Division of Research Services, National Institutes of Health, Bethesda, Maryland 20014, USA
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16
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Richardson RJ, Grkovic I, Allen AM, Anderson CR. Separate neurochemical classes of sympathetic postganglionic neurons project to the left ventricle of the rat heart. Cell Tissue Res 2006; 324:9-16. [PMID: 16418838 DOI: 10.1007/s00441-005-0105-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 10/25/2005] [Indexed: 11/26/2022]
Abstract
The sympathetic innervation of the rat heart was investigated by retrograde neuronal tracing and multiple label immunohistochemistry. Injections of Fast Blue made into the left ventricular wall labelled sympathetic neurons that were located along the medial border of both the left and right stellate ganglia. Cardiac projecting sympathetic postganglionic neurons could be grouped into one of four neurochemical populations, characterised by their content of calbindin and/or neuropeptide Y (NPY). The subpopulations of neurons contained immunoreactivity to both calbindin and NPY, immunoreactivity to calbindin only, immunoreactivity to NPY only and no immunoreactivity to calbindin or NPY. Sympathetic postganglionic neurons were also labelled in vitro with rhodamine dextran applied to the cut end of a cardiac nerve. The same neurochemical subpopulations of sympathetic neurons were identified by using this technique but in different proportions to those labelled from the left ventricle. Preganglionic terminals that were immunoreactive for another calcium-binding protein, calretinin, preferentially surrounded retrogradely labelled neurons that were immunoreactive for both calbindin and NPY. The separate sympathetic pathways projecting to the rat heart may control different cardiac functions.
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Affiliation(s)
- R J Richardson
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia.
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17
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Horiuchi J, McAllen RM, Allen AM, Killinger S, Fontes MAP, Dampney RAL. Descending vasomotor pathways from the dorsomedial hypothalamic nucleus: role of medullary raphe and RVLM. Am J Physiol Regul Integr Comp Physiol 2004; 287:R824-32. [PMID: 15205184 DOI: 10.1152/ajpregu.00221.2004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The dorsomedial hypothalamic nucleus (DMH) is believed to play a key role in mediating vasomotor and cardiac responses evoked by an acute stress. Inhibition of neurons in the rostral ventrolateral medulla (RVLM) greatly reduces the increase in renal sympathetic nerve activity (RSNA) evoked by activation of the DMH, indicating that RVLM neurons mediate, at least in part, the vasomotor component of the DMH-evoked response. In this study, the first aim was to determine whether neurons in the medullary raphe pallidus (RP) region also contribute to the DMH-evoked vasomotor response, because it has been shown that the DMH-evoked tachycardia is mediated by the RP region. The second aim was to directly assess the effect of DMH activation on the firing rate of RVLM sympathetic premotor neurons. In urethane-anesthetized rats, injection of the GABA(A) receptor agonist muscimol (but not vehicle solution) in the RP region caused a modest ( approximately 25%) but significant reduction in the increase in RSNA evoked by DMH disinhibition (by microinjection of bicuculline). In other experiments, disinhibition of the DMH resulted in a powerful excitation (increase in firing rate of approximately 400%) of 5 out of 6 spinally projecting barosensitive neurons in the RVLM. The results indicate that neurons in the RP region make a modest contribution to the renal sympathoexcitatory response evoked from the DMH and also that sympathetic premotor neurons in the RVLM receive strong excitatory inputs from DMH neurons, consistent with the view that the RVLM plays a key role in mediating sympathetic vasomotor responses arising from the DMH.
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Affiliation(s)
- J Horiuchi
- Dept. of Physiology, F13, The Univ. of Sydney, NSW 2006, Australia
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18
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Lee J, Albiston AL, Allen AM, Mendelsohn FAO, Ping SE, Barrett GL, Murphy M, Morris MJ, McDowall SG, Chai SY. Effect of I.C.V. injection of AT4 receptor ligands, NLE1-angiotensin IV and LVV-hemorphin 7, on spatial learning in rats. Neuroscience 2004; 124:341-9. [PMID: 14980384 DOI: 10.1016/j.neuroscience.2003.12.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 11/24/2003] [Accepted: 12/01/2003] [Indexed: 10/26/2022]
Abstract
Central administration of angiotensin IV (Ang IV) or its analogues enhance performance of rats in passive avoidance and spatial memory paradigms. The purpose of this study was to examine the effect of a single bolus injection of two distinct AT4 ligands, Nle1-Ang IV or LVV-haemorphin-7, on spatial learning in the Barnes circular maze. Mean number of days for rats treated with either Nle1-Ang IV or LVV-haemorphin-7 to achieve learner criterion is significantly reduced compared with controls (P < 0.001 and P < 0.05 respectively). This is due to enhanced ability of the peptide-treated rats to adopt a spatial strategy for finding the escape hatch. In all three measures of learning performance, (1) the number of errors made, (2) the distance travelled and (3) the latency in finding the escape hatch, rats treated with either 100 pmol or 1 nmol of Nle1-Ang IV or 100 pmol LVV-haemorphin-7 performed significantly better than the control groups. As early as the first day of testing, the rats treated with the lower dose of Nle1-Ang IV or LVV-haemorphin-7 made fewer errors (P < 0.01 and P < 0.05 respectively) and travelled shorter distances (P < 0.05 for both groups) than the control animals. The enhanced spatial learning induced by Nle1-Ang IV (100 pmol) was attenuated by the co-administration of the AT4 receptor antagonist, divalinal-Ang IV (10 nmol). Thus, administration of AT4 ligands results in an immediate potentiation of learning, which may be associated with facilitation of synaptic transmission and/or enhancement of acetylcholine release.
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Affiliation(s)
- J Lee
- Howard Florey Institute of Experimental Physiology and Medicine, The University of Melbourne, Parkville, Victoria 3010, Australia
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19
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Abstract
This study examined the role of the diagonal band of Broca (DBB) in drinking behaviour and vasopressin release. Adult male rats were anaesthetized (pentobarbital 50 mg/kg) and received DBB injections of either ibotenic acid (0.5 microl of 5 micro g/ microl) or vehicle (0.5 microl of phosphate-buffered saline). Although baseline drinking and urine output were not affected, drinking to 30% polyethylene glycol (MW 8000; 1 ml/100 g s.c.) and angiotensin II (0, 1.5 and 3.0 mg/kg s.c.) were significantly increased in ibotenic acid in phosphate-buffered saline (DBBX) rats. Drinking to hypertonic saline (0.9, 4 and 6%; 1 ml/100 g), and water deprivation were not significantly affected. DBBX rats had significantly lower basal heart rates than controls but the cardiovascular responses to infusions of angiotensin II (100 ng/kg/min i.v. for 45 min) were not affected. DBBX rats had significantly higher basal vasopressin, but angiotensin-stimulated vasopressin release was not significantly different. Although the DBB is not involved in basal water intake, it is involved in dipsogenic responses to hypovolemic stimuli and possibly basal autonomic function and basal vasopressin release.
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Affiliation(s)
- M J Sullivan
- Department of Physiology and the Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA
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20
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McKinley MJ, Albiston AL, Allen AM, Mathai ML, May CN, McAllen RM, Oldfield BJ, Mendelsohn FAO, Chai SY. The brain renin-angiotensin system: location and physiological roles. Int J Biochem Cell Biol 2003; 35:901-18. [PMID: 12676175 DOI: 10.1016/s1357-2725(02)00306-0] [Citation(s) in RCA: 391] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Angiotensinogen, the precursor molecule for angiotensins I, II and III, and the enzymes renin, angiotensin-converting enzyme (ACE), and aminopeptidases A and N may all be synthesised within the brain. Angiotensin (Ang) AT(1), AT(2) and AT(4) receptors are also plentiful in the brain. AT(1) receptors are found in several brain regions, such as the hypothalamic paraventricular and supraoptic nuclei, the lamina terminalis, lateral parabrachial nucleus, ventrolateral medulla and nucleus of the solitary tract (NTS), which are known to have roles in the regulation of the cardiovascular system and/or body fluid and electrolyte balance. Immunohistochemical and neuropharmacological studies suggest that angiotensinergic neural pathways utilise Ang II and/or Ang III as a neurotransmitter or neuromodulator in the aforementioned brain regions. Angiotensinogen is synthesised predominantly in astrocytes, but the processes by which Ang II is generated or incorporated in neurons for utilisation as a neurotransmitter is unknown. Centrally administered AT(1) receptor antagonists or angiotensinogen antisense oligonucleotides inhibit sympathetic activity and reduce arterial blood pressure in certain physiological or pathophysiological conditions, as well as disrupting water drinking and sodium appetite, vasopressin secretion, sodium excretion, renin release and thermoregulation. The AT(4) receptor is identical to insulin-regulated aminopeptidase (IRAP) and plays a role in memory mechanisms. In conclusion, angiotensinergic neural pathways and angiotensin peptides are important in neural function and may have important homeostatic roles, particularly related to cardiovascular function, osmoregulation and thermoregulation.
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Affiliation(s)
- M J McKinley
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Melbourne 3010, Vic., Australia.
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21
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Abstract
PURPOSE To examine the ability of standard dose-volume metrics to predict pulmonary function changes as measured by pulmonary function tests (PFTs) in a group of patients with non-small-cell lung cancer treated with nonconventional beam arrangements on a Phase I dose-escalation study. In addition, we wanted to examine the correlation between these metrics. MATERIALS AND METHODS Forty-three patients received a median treatment dose of 76.9 Gy (range 63-102.9). Eight patients also received induction chemotherapy with cisplatin and vinorelbine. They all had pre- and posttreatment PFTs >/=3 months (median 6.2) after treatment. The volume of normal lung treated to >20 Gy, effective volume, and mean lung dose were calculated for both lungs for all patients. Linear regression analysis was performed to determine whether correlations existed between the metrics and changes in the PFTs. Additionally, the three metrics were compared with each other to assess the degree of intermetric correlation. RESULTS No correlation was found between the volume of normal lung treated to >20 Gy, effective volume, and mean lung dose and changes in the PFTs. Subgroup analyses of patients without atelectasis before irradiation, Stage I and II disease, or treatment without induction chemotherapy were also performed. Again, no correlation was found between the dose-volume metrics and the PFT changes. The intermetric correlation was good among all three dose-volume metrics. CONCLUSIONS In this relatively small series of patients, dose-volume metrics that correlate with the risk of pneumonitis did not provide a good model to predict early changes in pulmonary function as measured with PFTs.
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Affiliation(s)
- A M Allen
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
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22
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McKinley MJ, Allen AM, May CN, McAllen RM, Oldfield BJ, Sly D, Mendelsohn FA. Neural pathways from the lamina terminalis influencing cardiovascular and body fluid homeostasis. Clin Exp Pharmacol Physiol 2001; 28:990-2. [PMID: 11903300 DOI: 10.1046/j.1440-1681.2001.03592.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The lamina terminalis, a region of the brain with a high concentration of angiotensin AT1 receptors, consists of three distinct nuclei, the median preoptic nucleus, the subfornical organ and organum vasculosum of the lamina terminalis (OVLT). These latter two regions lack a blood-brain and detect changes in plasma angiotensin (Ang) II concentration and osmolality. 2. Efferent neural pathways from the lamina terminalis to the hypothalamic paraventricular and supraoptic nuclei mediate vasopressin secretion in response to plasma hypertonicity and increased circulating levels of AngII. 3. Studies using the neurotropic virus pseudorabies, which undergoes retrograde transynaptic neuronal transport following injection into peripheral sites, show that neurons in the lamina terminalis have efferent polysynaptic neural connections to the peripheral sympathetic nervous system. Some of these neurons have been shown to have polysynaptic connections to the kidney and to express AT1 receptor mRNA. We propose that circulating AngII acts at AT1 receptors in the subfornical organ and OVLT to influence the sympathetic nervous system. It is likely that the neural pathway subserving this influence involves a synapse in the hypothalamic paraventricular nucleus. 4. The lamina terminalis may exert an inhibitory osmoregulatory influence on renin secretion by the kidney. This osmoregulatory influence may be mediated by inhibition of renal sympathetic nerve activity and appears to involve a central angiotensinergic synapse. 5. The lamina terminalis exerts an osmoregulatory influence on renal sodium excretion that is independent of the renal nerves and is probably hormonally mediated.
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Affiliation(s)
- M J McKinley
- Howard Florey Institute of Experimental Physiology, University of Melbourne, Parkville, Victoria, Australia.
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23
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Abstract
Angiotensinogen, the precursor molecule of the peptides angiotensin I, II, and III, is synthesized in the brain and the liver. Evidence is reviewed that angiotensin II, and possibly angiotensin III, that are generated within the brain act within neural circuits of the central nervous system to regulate body fluid balance. Immunohistochemical studies in the rat brain have provided evidence of angiotensin-containing neurons, especially in the hypothalamic paraventricular nucleus, subfornical organ, periventricular region, and nucleus of the solitary tract, as well as in extensive angiotensin-containing fiber pathways. Angiotensin immunoreactivity is observed by electron microscope in synaptic vesicles in several brain regions, the most prominent of these being the central nucleus of the amygdala. Neurons in many parts of the brain (lamina terminalis, paraventricular and parabrachial nuclei, ventrolateral medulla, and nucleus of the solitary tract) known to be involved in the regulation of body fluid homeostasis exhibit angiotensin receptors of the AT(1) subtype. Pharmacological studies in several species show that intracerebroventricular administration of AT(1) receptor antagonist drugs inhibit homeostatic responses to the central administration of hypertonic saline, intravenous infusion of the hormone relaxin, or thermal dehydration. Responses affected by centrally administered AT(1) antagonists are water drinking, vasopressin secretion, natriuresis, increased arterial pressure, reduced renal renin release, salt hunger, and thermoregulatory adjustments. We conclude that angiotensinergic neural pathways in the brain probably have an important homeostatic function, especially in regard to osmoregulation and thermoregulation, and the maintenance of arterial pressure.
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Affiliation(s)
- M J McKinley
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria 3010, Australia.
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24
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Boscan P, Allen AM, Paton JF. Baroreflex inhibition of cardiac sympathetic outflow is attenuated by angiotensin II in the nucleus of the solitary tract. Neuroscience 2001; 103:153-60. [PMID: 11311796 DOI: 10.1016/s0306-4522(00)00559-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Homeostatic regulation of arterial pressure is maintained by arterial baroreceptors. Activation of these receptors results in an inhibition of sympathetic activity to the heart. It is known that angiotensin II in the nucleus tractus solitarii attenuates the baroreceptor reflex-evoked vagal bradycardia. Here, we determined whether the cardiac sympathetic component of the baroreceptor reflex could be modulated by angiotensin II in the nucleus of the solitary tract. An in situ, arterially perfused working heart--brainstem preparation of rat was employed and the sympathetic inferior cardiac nerve recorded. Increases in perfusion pressure caused a reflex bradycardia and inhibition of inferior cardiac nerve activity. Microinjection of angiotensin II (500 fmol) in the nucleus of the solitary tract attenuated significantly both the reflex bradycardia and inhibition of inferior cardiac nerve activity (P<0.01). The latter was reversible and sensitive to losartan, an angiotensin II type 1 receptor antagonist. In contrast, the peripheral chemoreceptor reflex evoked an increase in inferior cardiac nerve activity that was not affected by angiotensin II applied exogenously in the nucleus of the solitary tract. We conclude that within the nucleus of the solitary tract angiotensin II exerts a powerful and specific inhibitory modulation of the baroreceptor reflex control of sympathetic nerve activity destined for the heart. We suggest that our data may have clinical implications relating to hypertension, a condition when angiotensin II activity is heightened in the brain and the efficacy of the baroreflex is reduced.
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Affiliation(s)
- P Boscan
- Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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25
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Abstract
The activity of sympathetic premotor neurons in the rostral ventrolateral medulla (subretrofacial nucleus) supports sympathetic vasomotor tone, but the factors that drive these premotor neurons' activity have not been determined. This study examines whether either direct interconnections between subretrofacial neurons or synchronizing common inputs to them are important for generating their tonic activity. Simultaneous extracellular single-unit recordings were made from 32 pairs of sympathetic premotor neurons in the subretrofacial nucleus of chloralose-anesthetized cats. Paired spike trains were either separated by spike shape from a single-electrode recording (14 pairs) or recorded from two electrodes less than 250 microm apart (18 pairs). All neurons were inhibited by carotid baroreceptor stimulation and most had a spinal axon proven by antidromic stimulation from the spinal cord. Autocorrelation, inter-spike interval, and cardiac cycle-triggered histograms were constructed from the spontaneous activity of each neuron, and cross-correlation histograms covering several time scales were generated for each neuron pair. No significant peaks or troughs were found in short-term cross-correlation histograms (2 ms bins, +/-100 ms range), providing no support for important local synaptic interactions. On an intermediate time scale (20 ms bins, +/-1 s range), cross-correlation revealed two patterns indicating shared, synchronizing inputs. Repeating peaks and troughs (19/32 pairs) were due to the two neurons' common cardiac rhythmicity, of presumed baroreceptor origin. Single, zero time-spanning peaks of 40--180 ms width were seen in 5/32 cases. Calculations based on the prevalence and strength of these synchronizing inputs indicate that most of the ensemble spike activity of the subretrofacial neuron population is derived from asynchronous sources (be they intrinsic or extrinsic). If synchronizing sources such as neuronal oscillators were responsible for more than a minor part of the drive, they would be multiple, dispersed, and weak.
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Affiliation(s)
- R M McAllen
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria 3010, Australia.
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26
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Lee J, Chai SY, Mendelsohn FA, Morris MJ, Allen AM. Potentiation of cholinergic transmission in the rat hippocampus by angiotensin IV and LVV-hemorphin-7. Neuropharmacology 2001; 40:618-23. [PMID: 11249971 DOI: 10.1016/s0028-3908(00)00188-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recent evidence demonstrates that the fragment of angiotensin II, angiotensin II (3-8) termed angiotensin IV, binds with high affinity to a specific binding site, the AT(4) receptor. Intracerebroventricular injection of AT(4) receptor agonists improves the performance of rats in passive avoidance and spatial learning paradigms. AT(4) receptors and cholinergic neurons are closely associated in regions involved in cognitive processing, such as the hippocampus and neocortex. We therefore postulated that AT(4) receptors affect cognitive processing by modulating cholinergic neurotransmission. To test this, we examined the effect of AT(4) receptor ligands, angiotensin IV and LVV-hemorphin-7, on potassium-evoked [(3)H]acetylcholine ([(3)H]ACh) release from rat hippocampal slices. Hippocampal slices from male Sprague--Dawley rats were incubated with [(3)H]choline chloride, perfused with Krebs--Henseleit solution and [(3)H]ACh release was determined. Angiotensin IV and LVV-hemorphin-7 both potentiated depolarisation-induced [(3)H]ACh release from the rat hippocampus in a concentration-dependent manner with the maximal dose (10(-7)M) of each inducing an increase of 45+/-7.5% (P<0.01) and 95.8+/-19% (P<0.01) above control, respectively. Potentiation of release by both agonists was attenuated by the AT(4) receptor antagonist, divalinal-Ang IV. Angiotensin IV-induced potentiation was not affected by AT(1) and AT(2) receptor antagonists. These results indicate that stimulation of AT(4) receptors can potentiate depolarisation-induced release of ACh from hippocampal slices and suggest that potentiation of cholinergic transmission may be a mechanism by which AT(4) receptor ligands enhance cognition.
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Affiliation(s)
- J Lee
- The Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Melbourne, Victoria 3010, Australia
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27
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Oldfield BJ, Davern PJ, Giles ME, Allen AM, Badoer E, McKinley MJ. Efferent neural projections of angiotensin receptor (AT1) expressing neurones in the hypothalamic paraventricular nucleus of the rat. J Neuroendocrinol 2001; 13:139-46. [PMID: 11168839 DOI: 10.1046/j.1365-2826.2001.00597.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Angiotensin II acts within the hypothalamic paraventricular nucleus (PVN) to help mediate a number of autonomic and endocrine responses. Evidence is sparse in regard to the particular neuronal cell groups that exhibit angiotensin II type 1 receptors within the PVN, and does not exist in relation to specified efferent neuronal populations in the nucleus. In the present experiments, retrogradely transported neuronal tracers were utilized in conjunction with immunohistochemistry using a well characterized polyclonal antibody raised against a decapeptide sequence at the carboxy terminus of the AT1 receptor, to determine whether it is preferentially distributed amongst different efferent populations within the PVN. The AT1 receptor is not associated with neurones in the PVN that project axons to the spinal cord, dorsomedial or ventrolateral medulla but coexists strongly with neurones in the anterior parvocellular division of the nucleus which direct axons to the median eminence. Such neurones often contain corticotropin releasing factor. These findings highlight the role that angiotensin II and AT1 receptors in the PVN may play in the mediation of responses to stress.
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Affiliation(s)
- B J Oldfield
- Howard Florey Institute, The University of Melbourne, Australia.
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28
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Chai SY, Allen AM, Zhuo J, Moeller I, Mendelsohn FA. Autoradiographic localization and quantification of components of the Renin-Angiotensin system in tissues. Methods Mol Med 2001; 51:315-337. [PMID: 21331727 DOI: 10.1385/1-59259-087-x:315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In situ radioligand binding with autoradiography allows localization and quantification of bound radiolabeled ligands in tissues. This is a very sensitive technique that enables the characterization of binding kinetics and ligand specificity and the quantification of the amount of radioligand bound in different structures within the tissue. This technique is complementary to the higher resolution of immunohistochemical localization of proteins or binding sites on fixed tissue sections and in situ hybridization histochemical localization of mRNA.
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Affiliation(s)
- S Y Chai
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia
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29
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Potts PD, Allen AM, Horiuchi J, Dampney RA. Does angiotensin II have a significant tonic action on cardiovascular neurons in the rostral and caudal VLM? Am J Physiol Regul Integr Comp Physiol 2000; 279:R1392-402. [PMID: 11004009 DOI: 10.1152/ajpregu.2000.279.4.r1392] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The peptidic ANG II receptor antagonists [Sar(1),Ile(8)]ANG II (sarile) or [Sar(1),Thr(8)]ANG II (sarthran) are known to decrease arterial pressure and sympathetic activity when injected into the rostral part of the ventrolateral medulla (VLM). In anesthetized rabbits and rats, the profound depressor and sympathoinhibitory response after bilateral microinjections of sarile or sarthran into the rostral VLM was unchanged after prior selective blockade of angiotensin type 1 (AT(1)) and ANG-(1---7) receptors, although this abolished the effects of exogenous ANG II. Unlike the neuroinhibitory compounds muscimol or lignocaine, microinjections of sarile in the rostral VLM did not affect respiratory activity. Sarile or sarthran in the caudal VLM resulted in a large pressor and sympathoexcitatory response, which was also unaffected by prior blockade of AT(1) and ANG-(1---7) receptors. The results indicate that the peptidic ANG receptor antagonists profoundly inhibit the tonic activity of cardiovascular but not respiratory neurons in the VLM and that these effects are independent of ANG II or ANG-(1---7) receptors.
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Affiliation(s)
- P D Potts
- Department of Physiology and Institute for Biomedical Research, The University of Sydney, New South Wales 2006, Australia
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30
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Abstract
Neurons in the rostral and caudal parts of the ventrolateral medulla (VLM) play a pivotal role in the regulation of sympathetic vasomotor activity and blood pressure. Studies in several species, including humans, have shown that these regions contain a high density of AT1 receptors specifically associated with neurons that regulate the sympathetic vasomotor outflow, or the secretion of vasopressin from the hypothalamus. It is well established that specific activation of AT1 receptors by application of exogenous angiotensin II in the rostral and caudal VLM excites sympathoexcitatory and sympathoinhibitory neurons, respectively, but the physiological role of these receptors in the normal synaptic regulation of VLM neurons is not known. In this paper we review studies which have defined the effects of specific activation or blockade of these receptors on cardiovascular function, and discuss what these findings tell us with regard to the physiological role of AT1 receptors in the VLM in the tonic and phasic regulation of sympathetic vasomotor activity and blood pressure.
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Affiliation(s)
- T Tagawa
- Department of Physiology and Institute for Biomedical Research, University of Sydney, Australia
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Allen AM. What to look out for if offered a reimbursement schedule that's less than Medicare. Del Med J 2000; 72:219-20. [PMID: 10835817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Abstract
The distributions of angiotensin AT1 and AT2 receptors have been mapped by in vitro autoradiography throughout most tissues of many mammals, including humans. In addition to confirming that AT1 receptors occur in sites known to be targets for the physiologic actions of angiotensin, such as the adrenal cortex and medulla, renal glomeruli and proximal tubules, vascular and cardiac muscle and brain circumventricular organs, many new sites of action have been demonstrated. In the kidney, AT1 receptors occur in high density in renal medullary interstitial cells. The function of these cells, which span the interstitial space between the tubules and the vasa rectae, remains to be determined. Renal medullary interstitial cells possess receptors for a number of vasoactive hormones in addition to AT1 receptors and this, in concert with their anatomic location, suggests they may be important for the regulation of fluid reabsorption or renal medullary blood flow. In the heart, the highest densities of AT1 receptors occur in association with the conduction system and vagal ganglia. In the central nervous system, high AT1 receptor densities occur in many regions behind the blood-brain barrier, supporting a role for neurally derived angiotensin as a neuromodulator. The physiologic role of angiotensin in many of these brain sites remains to be determined. The AT2 receptor also has a characteristic distribution in several tissues including the adrenal gland, heart, and brain. The role of this receptor in physiology is being elucidated, but it appears to inhibit proliferation and to participate in development. Thus, receptor-binding studies, localizing the distribution of AT1 and AT2 receptors, provide many insights into novel physiologic roles of angiotensin.
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Affiliation(s)
- A M Allen
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia
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Abstract
The distribution of angiotensin AT1 and AT2 receptors in the human central nervous system has been mapped and is reviewed here. The results discussed provide the anatomical basis for inferences regarding the physiological role of angiotensin in the human brain. The distribution of the AT2 receptor is very restricted in the human brain and shows a high degree of variability across species. The physiological role of this receptor in the adult central nervous system is not clear. In contrast, a high correlation exists between the distributions of AT1 receptors in the human and other mammalian brains studied. This pattern of distribution suggests that angiotensin, acting through the AT1 receptor, would act as a neuromodulator or neurotransmitter in the human central nervous system to influence fluid and electrolyte homeostasis, pituitary hormone release and autonomic control of cardiovascular function.
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Affiliation(s)
- A M Allen
- The Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Australia.
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Allen AM, Zhuo J, Mendelsohn FA. Localization of angiotensin AT1 and AT2 receptors. J Am Soc Nephrol 1999; 10 Suppl 11:S23-9. [PMID: 9892137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
The distributions of angiotensin AT1 and AT2 receptors have been mapped by in vitro autoradiography throughout most tissues of many mammals, including humans. In addition to confirming that AT1 receptors occur in sites known to be targets for the physiologic actions of angiotensin, such as the adrenal cortex and medulla, renal glomeruli and proximal tubules, vascular and cardiac muscle, and brain circumventricular organs, many new sites of action have been demonstrated. In the kidney, AT1 receptors occur in high density in renal medullary interstitial cells. The function of these cells, which span the interstitial space between the tubules and the vasa rectae, remains to be determined. Renal medullary interstitial cells possess receptors for a number of vasoactive hormones in addition to AT1 receptors and this, in concert with their anatomical location, suggest that they may be important for the regulation of fluid reabsorption or renal medullary blood flow. In the heart, the highest densities of AT1 receptors occur in association with the conduction system and vagal ganglia. In the central nervous system, high AT1 receptor densities occur in many regions behind the blood-brain barrier, supporting a role for neurally derived angiotensin as a neuromodulator. The physiologic role of angiotensin in many of these brain sites remains to be determined. The AT2 receptor also has a characteristic distribution in several tissues including the adrenal gland, heart, and brain. The role of this receptor in physiology is being elucidated, but it appears to participate in development. Thus, receptor binding studies, localizing the distribution of AT1 and AT2 receptors, outline a number of regions where the actions of angiotensin are known but also provide many insights into novel physiologic roles of this peptide.
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Affiliation(s)
- A M Allen
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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Zhuo J, Moeller I, Jenkins T, Chai SY, Allen AM, Ohishi M, Mendelsohn FA. Mapping tissue angiotensin-converting enzyme and angiotensin AT1, AT2 and AT4 receptors. J Hypertens 1998; 16:2027-37. [PMID: 9886893 DOI: 10.1097/00004872-199816121-00026] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The renin-angiotensin system (RAS) functions as both a circulating endocrine system and a tissue paracrine/autocrine system. As a circulating peptide, angiotensin II (Ang II) plays a prominent role in blood-pressure control and body fluid and electrolyte balance by acting on the AT1 receptor in the brain and peripheral tissues. As a paracrine/autocrine peptide, locally formed Ang II also plays additional roles in tissues involving the regulation of regional haemodynamics, cell growth and remodelling, and neurotransmitter release. Evidence is emerging that Ang II is not the only active peptide of the RAS, and other Ang II fragments may also have important biological activities. OBJECTIVES To provide a morphological basis for understanding novel actions of angiotensin-converting enzyme (ACE), Ang II and related peptides in tissues, this article will review the localization of ACE and AT1, AT2 and AT4 receptors in the central nervous system, blood vessels and kidney. RESULTS AND CONCLUSION Autoradiographic mapping of the major components of the RAS has proved a valuable strategy to reveal, or suggest, cellular sites of novel actions for Ang II and related peptides in tissues. First, colocalization of ACE and AT1 receptors in the substantia nigra, the caudate nucleus and putamen of human and rat brain, which contain the dopamine-synthesizing neurons, suggests that the central RAS may be important in modulating central dopamine release. Secondly, the distribution of AT4 receptors with a striking association with cholinergic neurons, motor and sensory nuclei in the brain reveals that Ang IV may modulate central motor and sensory activities and memory. Thirdly, the occurrence of high levels of ACE and AT1 and/or AT2 receptors in the adventitia of blood vessels suggests important paracrine roles of the vascular RAS. Finally, the identification of abundant AT1 receptor and elucidation of its roles in the renomedullary interstitial cells of the kidney may provide a new impetus to study further the role of Ang II in the regulation of renal medullary function and blood pressure. Overall, circulating and locally produced Ang II and related peptides may exert a remarkable range of actions in the brain, kidney and cardiovascular system through multiple angiotensin receptors.
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Affiliation(s)
- J Zhuo
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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McKinley MJ, Allen AM, Burns P, Colvill LM, Oldfield BJ. Interaction of circulating hormones with the brain: the roles of the subfornical organ and the organum vasculosum of the lamina terminalis. Clin Exp Pharmacol Physiol Suppl 1998; 25:S61-7. [PMID: 9809195 DOI: 10.1111/j.1440-1681.1998.tb02303.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Most circulating peptide hormones are excluded from much of the brain by the blood-brain barrier. However, they do have access to the circumventricular organs (CVO), which lack the blood-brain barrier. Three of the CVO, the subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT) and area postrema, contain neurons responsive to peptides such as angiotensin II (AngII), atrial natriuretic peptide and relaxin. 2. We have studied the patterns of neuronal activation, as shown by Fos expression, in the SFO and OVLT in response to systemically infused AngII, relaxin or hypertonic saline and have found subgroups of neurons activated by the different stimuli. 3. Systemic infusion of relaxin or hypertonic saline activated neurons almost exclusively in the outer regions of the SFO and in the dorsal cap of the OVLT. Many of these neurons send axonal projections to regions of the brain subserving vasopressin secretion and thirst, such as the median preoptic, supraoptic and hypothalamic paraventricular nuclei. 4. At moderate blood concentrations, AngII only stimulates neurons in the inner core of the SFO and lateral regions of the OVLT. Higher levels of AngII in the bloodstream activate additional neurons in the outer parts of the SFO that connect to the supraoptic, paraventricular and median preoptic nuclei and these probably mediate water drinking and vasopressin secretion induced by blood-borne AngII. The efferent connections and the functions mediated by angiotensin-sensitive neurons in the inner core of the SFO and lateral part of the OVLT are unknown.
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Affiliation(s)
- M J McKinley
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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Abstract
In addition to its traditional role as a circulating hormone, angiotensin is also involved in local functions through the activity of tissue renin-angiotensin systems that occur in many organs, including the brain. In the brain, both systemic and presumptive neurally derived angiotensin and angiotensin metabolites act through specific receptors to modulate many functions. This review examines the distribution of these specific angiotensin receptors and discusses evidence regarding the function of angiotensin peptides in various brain regions. Angiotensin AT1 and AT2 receptors occur in characteristic distributions that are highly correlated with the distribution of angiotensin-like immunoreactivity in nerve terminals. Acting through the AT1 receptor in the brain, angiotensin has effects on fluid and electrolyte homeostasis, neuroendocrine systems, autonomic pathways regulating cardiovascular function and behavior. Angiotensin AT1 receptors are also found in many afferent and efferent components of the peripheral autonomic nervous system. The role of the AT2 receptor in the brain is less well understood, although recent knockout studies point to an involvement with behavioral and cardiovascular functions. In addition to the AT1 and AT2 receptors, receptors for other fragments of angiotensin have been proposed. The AT4 binding site, which binds angiotensin, has a widespread distribution in the brain quite distinct from that of the AT1 and AT2 receptors. It is associated with many cholinergic neuronal groups and also several sensory nuclei, but its function remains to be determined. Our discovery that another brain-derived peptide binds to the AT4 binding site in the brain and may represent the native ligand is discussed. Overall, the distribution of angiotensin receptors in the brain indicate that they play diverse and important physiological roles in the nervous system.
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Affiliation(s)
- A M Allen
- The Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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Abstract
1. A high density of angiotensin II receptors was observed in the rat carotid body by in vitro autoradiography employing 125I-[Sar1, Ile8]-angiotensin II as radioligand. Displacement studies demonstrated that the receptors were of the AT1 subtype. 2. The binding pattern indicated that the AT1 receptors occurred over clumps of glomus cells, the principal chemoreceptor cell of the carotid body. Selective lesions of the sympathetic or afferent innervation of the carotid body had little effect on the density of receptor binding, demonstrating that the majority of AT1 receptors were intrinsic to the glomus cells. 3. To determine the direct effect of angiotensin II on chemoreceptor function, without the confounding effects of the vasoconstrictor action of angiotensin II, carotid sinus nerve activity was recorded from the isolated carotid body in vitro. The carotid body was superfused with Tyrode solution saturated with carbogen (95 % O2, 5 % CO2), maintained at 36 C, and multi-unit nerve activity recorded with a suction electrode. 4. Angiotensin II elicited a dose-dependent excitation of carotid sinus nerve activity (maximum increase of 36 +/- 11 % with 10 nM angiotensin II) with a threshold concentration of 1 nM. The response was blocked by the addition of an AT1 receptor antagonist, losartan (1 microM), but not by the addition of an AT2 receptor antagonist, PD123319 (1 microM). 5. In approximately 50 % of experiments the excitation was preceded by an inhibition of activity (maximum decrease of 24 +/- 8 % with 10 nM angiotensin II). This inhibitory response was markedly attenuated by losartan but not affected by PD123319. 6. These observations demonstrate that angiotensin II, acting through AT1 receptors located on glomus cells in the carotid body, can directly alter carotid chemoreceptor afferent activity. This provides a means whereby humoral information about fluid and electrolyte homeostasis might influence control of cardiorespiratory function.
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Affiliation(s)
- A M Allen
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria 3052, Australia.
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Abstract
Angiotensin II is recognised as the principle active peptide of the renin-angiotensin system, exerting effects on fluid and electrolyte homeostasis, and cardiovascular control including neural and long term trophic effects. However, recent studies indicate that other angiotensin peptides such as angiotensin III, angiotensin II (1-7) and angiotensin IV, may have specific actions. Interestingly, recent work involving angiotensin IV demonstrates that this peptide binds to specific receptors and may be involved in memory retention and neuronal development. Furthermore, our demonstration that a globin fragment, LVV-haemorphin-7, binds with high affinity to the angiotensin IV binding site and is abundant in the brain, indicates that this may represent a novel brain neuropeptide system. It now appears, that the renin-angiotensin system is more complex than previously thought and capable of generating multiple, active peptides which elicit numerous diverse actions.
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Affiliation(s)
- I Moeller
- The Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia
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Abstract
The spring ligament is a significant contributor to the stability of the talar head and longitudinal arch of the foot, lending importance to accurate radiologic diagnosis of injury. Using MR, we diagnosed a spring ligament tear with associated navicular dorsal subluxation, confirmed intraoperatively. To our knowledge, there are no previous reports of MR diagnosis of tear of the spring ligament.
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Affiliation(s)
- J P Chen
- Department of Radiology, University of Tennessee Medical Center, Knoxville 37920, USA
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Abstract
There is a large body of evidence to support the concept of a relationship between brain Ang II and catecholamine systems. This interaction may participate in some central actions of Ang II such as cardiovascular control, dipsogenesis, and complex behaviours. It also extends to the nigrostriatal dopaminergic system which bear AT1 receptors, both on their cell bodies in the substantia nigra presynaptically, and on their terminals in the striatum, where Ang II can markedly potentiate DA release. This observation suggests that drugs which modulate central Ang II may be useful in regulating central dopaminergic activity.
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Affiliation(s)
- T A Jenkins
- University of Melbourne, Department of Medicine, Austin Hospital, Victoria, Australia
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Allen AM. Stressors to neonates in the neonatal unit. Midwives (1995) 1995; 108:139-40. [PMID: 7767758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Abstract
The distribution of the AT1 and AT2 subtypes of angiotensin II receptor was mapped in the adult human central nervous system using quantitative in vitro autoradiography. Binding in all forebrain, midbrain, pontine, medullary and spinal cord sites where angiotensin II receptors have previously been described is of the AT1 subtype, as is binding in the small and large arteries in the adjacent meninges and in choroid plexus. By contrast, both AT1 and AT2 receptors occur in the molecular layer of the cerebellum. Angiotensin II AT1 receptors in the brain show a moderate degree of conservation across mammalian species studied so far, whereas expression of AT2 receptors is more variable, and is more restricted in the human CNS than in many other mammals. These differences between the subtype distributions in humans and other animals indicate the need for care when extrapolating the results of animal studies involving the brain angiotensin system.
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Affiliation(s)
- D P MacGregor
- Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Australia
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Allen AM, Ward WG, Pope TL. Imaging of the total knee arthroplasty. Radiol Clin North Am 1995; 33:289-303. [PMID: 7871170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have reviewed the essentials of TKA imaging. Because the purpose of a knee arthroplasty is to relieve pain and improve function, radiographs should be viewed in the context of these goals.
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Affiliation(s)
- A M Allen
- Department of Radiology, University of Tennessee Medical Center, Knoxville
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Abstract
A content analysis was conducted to evaluate the coverage of the new food labels in the print media from December 1, 1992, to August 30, 1993. We used newspaper, magazine, and health newsletter indexes to identify 59 newspaper articles, 16 magazine articles, and 7 health newsletter articles for examination. Articles were evaluated by four trained coders using a pretested coding form addressing 35 aspects of the nutrition label coverage. Twenty percent of articles were double-coded with at least 80% coder reliability. Analysis of the data indicated that health newsletters covered the topic in the most detail, followed by magazines and then newspapers. Ten of 59 (17%) newspaper articles named and defined the term percent daily value, whereas 6 of 7 (86%) health newsletter articles and 9 of 16 (56%) magazine articles provided this information. Analysis of quotes in the articles indicated that more than half of the quotes were from government and industry officials. In contrast, quotes from college and university faculty represented only 5% of total quotes and quotes from dietitians represented less than 8% of total quotes. Coders identified several errors resulting from oversimplification of complex concepts. These findings suggest that dietitians need to increase their exposure with the media and help the media translate complex nutrition labeling information to the public.
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Affiliation(s)
- A M Allen
- Hood College, Frederick, MD 21701-8575
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Abstract
OBJECTIVE In a search for ancillary MR findings for the diagnosis of spondylolysis, we performed a retrospective study to characterize changes in MR signal intensity of marrow within lumbar pedicles at the level of a spondylolytic defect. These reactive marrow changes were classified according to the anatomic-pathologic scheme developed for degenerative disk disease by Modic et al. MATERIALS AND METHODS Two neuroradiologists retrospectively reviewed MR images of 60 patients with lumbar spondylolysis confirmed by conventional radiography or CT. The MR signal of each pedicle at the level of a pars defect was compared on T1- and T2-weighted sagittal images to that at the next higher level. When both observers concurred that the signal of the involved pedicle differed significantly from that of its neighbor, this signal change was classified into one of three types (type I: hypointense on T1-weighted images, hyperintense on T2-weighted images; type II: hyperintense on T1-weighted images, isointense or hyperintense on T2-weighted images; type III: hypointense on both T1- and T2-weighted images). RESULTS Changes in MR signal intensity of pedicles adjacent to spondylolytic defects were observed in 24 (40%) of the 60 patients. Type I changes were seen in three patients, all less than 24 years old. Type II changes were seen in 17 patients with a median age of 35 years. Type III changes were seen in four patients with a median age of 51 years. The distribution of changes in signal intensity in the pedicle as a function of age was significant (p = .001). CONCLUSION Categories of changes in MR signal intensity, similar to those described adjacent to degenerating disks, can be seen in lumbar pedicles adjacent to a spondylolytic defect of the pars interarticularis and are distributed as a function of age. Awareness of this finding may aid in establishing the correct diagnosis of spondylolysis on MR imaging and prevent erroneous interpretation of abnormal signal intensity in the pedicles in these patients.
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Affiliation(s)
- J L Ulmer
- Department of Radiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1022
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Allen AM. The Board of Healing Arts is solving problems through communication with physicians. Mo Med 1995; 92:74-6. [PMID: 7746248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Abstract
There is a large body of anatomical and functional evidence supporting an interaction between brain angiotensin and central catecholamine systems. Angiotensin II AT1 receptors have been identified on dopamine containing cells in the substantia nigra and striatum of human brain using receptor autoradiography. Using in vivo microdialysis we have demonstrated that locally administered angiotensin II stimulates dopamine release from the striatum of conscious rats. Since some angiotensin receptor antagonists and angiotensin converting enzyme inhibitors can cross the blood brain barrier it is possible that they interact with the brain catecholaminergic systems.
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Affiliation(s)
- T A Jenkins
- Department of Medicine, University of Melbourne, Austin Hospital Heidelberg, Victoria
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Abstract
The distribution of angiotensin II binding sites has been mapped at segmental levels throughout the spinal cord of the sheep using in vitro autoradiographic methods. Binding of 125I-[Sar1.Ile8] Ang II is most prominent in the lateral horns of the thoracolumbar and sacral regions containing the sympathetic and parasympathetic preganglionic neurons respectively. Binding is also present in the dorsal horns of the grey matter, in the central canal region, dorsal root ganglia and associated with non-neuronal elements such as the ependyma surrounding the central canal, and blood vessels. Displacement with receptor antagonists specific for AT1 and AT2 subtypes, indicates that angiotensin II receptors in the spinal cord are of the AT1 type. These data help to interpret the physiological actions of angiotensin II in the spinal cord, particularly with respect to its autonomic components.
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Affiliation(s)
- B J Oldfield
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Vic, Australia
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Allen AM. Medical mission in Haiti. Mo Med 1994; 91:284-6. [PMID: 8052217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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