Stress reactivity of the brain noradrenergic system in three rat strains differing in their neuroendocrine and behavioral responses to stress: implications for susceptibility to stress-related neuropsychiatric disorders

The brain noradrenergic system is activated by stress, modulating the activity of forebrain regions involved in behavioral and neuroendocrine responses to stress. In this study, we characterized brain noradrenergic reactivity to acute immobilization stress in three rat strains that differ in their neuroendocrine stress response: the inbred Lewis (Lew) and Wistar-Kyoto (WKY) rats, and outbred Sprague-Dawley (SD) rats. Noradrenergic reactivity was assessed by measuring tyrosine hydroxylase mRNA expression in locus coeruleus, and norepinephrine release in the lateral bed nucleus of the stria terminalis. Behavioral measures of arousal and acute stress responsivity included locomotion in a novel environment, fear-potentiated startle, and stress-induced reductions in social interaction and open-arm exploration on the elevated-plus maze. Neuroendocrine responses were assessed by plasma adrenocorticotropic hormone. Compared to SD, adrenocorticotropic hormone responses of Lew rats were blunted, whereas those of WKY were enhanced. The behavioral effects of stress were similar in Lew and SD rats, despite baseline differences. Lew had similar elevations of tyrosine hydroxylase mRNA, and initially greater norepinephrine release in the lateral bed nucleus of the stria terminalis during stress, although both noradrenergic responses returned toward baseline more rapidly than in SD rats. WKY rats showed depressed baseline startle and lower baseline exploratory and social behavior than SD. However, unlike the Lew or SD rats, WKY exhibited a lack both of fear potentiation of the startle response and of stress-induced reductions in exploratory and social behavior, indicating attenuated stress responsivity. Acute noradrenergic reactivity to stress, measured by either tyrosine hydroxylase mRNA levels or norepinephrine release, was also attenuated in WKY rats. Thus, reduced arousal and behavioral responsivity in WKY rats may be related to deficient brain noradrenergic reactivity. This deficit may alter their ability to cope with stress, resulting in the exaggerated neuroendocrine responses and increased susceptibility to stress-related pathology exhibited by this strain.

Risk factors for delayed healing and long-term recurrence in chronic venous leg ulcers

Background

This study aimed to identify risk factors for delayed healing and increased recurrence of chronic venous leg ulcers.

Methods

Some 669 patients with chronic leg ulcers were assessed at a one-stop clinic over the 4 years to July 1999. Possible risk factors and venous reflux patterns, assessed with colour duplex, were recorded prospectively for each patient. Some 633 legs with an ankle: brachial pressure index greater than 0·85 were treated with weekly four-layer bandaging until healed, followed by class 2 compression stockings and regular follow-up. Patients with isolated superficial venous reflux were offered surgery.

Results

Cox regression analyses of possible risk factors are summarized in the Table below.

Conclusion

Age, ulcer chronicity and reflux in the popliteal vein are independent risk factors for delayed ulcer healing. Delayed ulcer healing and rheumatoid arthritis are independent risk factors for ulcer recurrence. Legs with surgically corrected superficial venous reflux are relatively protected from ulcer recurrence.

Genetic dissection of seed shattering, agronomic, and color traits in American wildrice ( Zizania palustris var. interior L.) with a comparative map

A comparative map of American wildrice ( Zizania palustris var. interior L.) was used to identify loci controlling seed shattering, plant height, maturity, tiller number, plant habit, panicle length seed length, and color traits. Two to six significant quantitative-trait-loci (QTLs, P < 0.05) were detected for each trait evaluated, representing the first trait-mapping in wildrice. The chosen population was designed to emphasize the mapping of loci controlling the shattering trait, which is the most important trait in the management of this newly domesticated species. Three loci were detected that controlled the discretely categorized variation between shattering and non-shattering plants. Seed-shattering loci were detected and validated among the F(2) and F(3) generations. A multiple regression model with these three loci described 49.6% of the additive genetic variation. A genetic model with the same three loci including dominance and locus interactions predicted the shattering versus non-shattering phenotype at a success rate of 87%. The comparative map was based on mapped RFLP markers used in white rice ( Oryza sativa L.) and other grass species. Anchor loci provided a reference point for the identification of potential orthologous genes on the basis of white rice mutant loci and consensus grass species QTLs. Candidate orthologous loci were identified among all traits evaluated. The study underscores the benefits of extending trait analysis through comparative mapping, as well as challenges of QTL analysis in a newly domesticated species.

A population pharmacokinetic-pharmacodynamic analysis and model validation of azimilide

BACKGROUND

Pharmacokinetic (PK) and pharmacodynamic (PD) models for azimilide were developed and validated with sparse blood sampling and QTc interval data obtained during three clinical trials of azimilide for prevention of supraventricular arrhythmia recurrence.

METHODS

Patients were orally administered placebo or azimilide dihydrochloride, 35, 50, 75, 100, or 125 mg/d, for 6 to 9 months. NONMEM was used for data fitting and assessment of selected patient covariates and concomitant medication classes for PK/PD relationships.

RESULTS

Results indicate that azimilide clearance (CL) was dependent on body weight (WTKG), gender, and current tobacco use, where CL (L/h) = 3.92 x (WTKG - 43)(0.208), with a 17% increase for male subjects and a 15.5% increase for current tobacco use. Volume of distribution (V) was also dependent on WTKG and total bilirubin (BIL), where V (L) = 9.88 x (WTKG - 43) + 717 x (BIL)(0.348). The PK/PD analysis indicated that the baseline QTc interval was dependent on gender, New York Heart Association Class, digoxin, and paced artificial pacemaker spike, whereas the 50% effective concentration (EC(50)) was dependent on the serum potassium (K) level, where EC(50) = 107 x K. The change in EC(50) was not clinically significant within the normal range for potassium. The mean E(max) (maximum increase in the QTc interval for the E(max) models) was a 61.7 ms increase from baseline. At 125 mg/d the predicted percent increase in the QTc interval at the maximum plasma drug concentration at steady state was 9% and 10% for male and female patients, respectively. The values of the median prediction error were -3% and -0.4% for the PK and PK/PD models, respectively, and the values of the absolute prediction error were 21% and 4% for the PK and PK/PD models, respectively, indicating that both models are essentially unbiased and acceptably accurate.

CONCLUSIONS

Azimilide PK parameters are dependent on body weight, gender, smoking status, and bilirubin and are independent of the coadministration of digoxin, warfarin, and cytochrome P4503A4 inhibitors and inducers. The relationship between azimilide concentration and change in QTc is primarily dependent on serum potassium.

Analysis of consumption of home-produced foods

One of the potential exposure pathways of concern when assessing human exposures to environmental contaminants is the ingestion of contaminated foods. Individuals who live near contaminated sites and who grow their own food may be at a higher risk than the general population. Estimating exposures to this subpopulation requires an analysis of homegrown food intake rates. The Nationwide Food Consumption Survey (NFCS) 1987-1988 data were used to generate intake rates for home-produced foods. Results of the analysis show that, among the general population, homegrown vegetables (18%) were the most commonly consumed of the major food groups, followed by fruit (8%), meat (5%), fish (2%), and dairy products (0.8%). The intake rates for the major food groups vary according to region, age, urbanization, and race. In general, intake rates of home-produced foods are higher among populations in non-metropolitan and suburban areas and lowest in central city areas.

Ethics and early intervention in psychosis: keeping up the pace and staying in step

The intense clinical and research interest in early psychosis in recent years has highlighted a range of ethical issues which need to be considered carefully. Our perspective is based on 16 years of clinical and research experience with young people at this phase of illness as well as the research contributions of many others. We discuss the ethical dilemmas in relation to the three key foci, which make up the early psychosis paradigm. These are the pre-psychotic or prodromal phase, the period of untreated psychosis and the first psychotic episode and the critical period of recovery, which follows this. Most attention is devoted to the pre-psychotic period, however ethical considerations related to research in the other two clinical foci are briefly covered as well. Our contention is that the ethical issues are essentially identical to those arising in early intervention research in mainstream medicine. This has been concealed by inconsistency and emotion, which has great potential to confuse, politicize and derail rational debate. The legacy of the isolation of psychiatry from medicine and consequent prejudice and stigma in the professional as well as the public mind seems to be fueling a tendency in some societies to view psychiatric research as qualitatively different from other medical research. Sound clinical research data should be allowed to illuminate the options for potential consumers across all phases of illness. The alternative is research paralysis, which would force clinical practice to expand blindly without an evidence base.

Defining the relationship between obesity and total joint arthroplasty

OBJECTIVE

The purpose of this study was to examine the relationship between obesity and patient-administered outcome measures after total joint arthroplasty.

RESEARCH METHODS AND PROCEDURES

A voluntary questionnaire-based registry contained 592 primary total hip arthroplasty patients and 1011 primary total knee arthroplasty patients with preoperative and 1-year data. Using logistic regression, the relationships between body mass index and the several outcome measures, including Short Form-36 and Western Ontario and McMaster Universities Osteoarthritis Index, were examined.

RESULTS

There was no difference between obese and non-obese patients regarding satisfaction, decision to repeat surgery, and Delta physical component summary, Delta mental component summary, and Delta Western Ontario and McMaster Universities Osteoarthritis Index scores (p > 0.05 for all). Body mass index was associated with an increased risk of having difficulty descending or ascending stairs at 1 year (odds ratio, 1.2 to 1.3).

DISCUSSION

Obese patients enjoy as much improvement and satisfaction as other patients from total joint arthroplasty.

Are pain disorder and somatization disorder valid diagnostic entities?

Physicians and other clinicians who treat patients with chronic pain have doubtless recognized the interplay of various psychological and somatic variables in their patients' pain. Notwithstanding, there continues to be primary emphasis on the somatic factors, and continued neglect of the psychological. This article asserts that pain disorder and somatization disorder are indeed valid diagnostic entities, and that their respective incidence and prevalence are quite high both in patients with chronic pain and in the primary care setting. These diagnoses are compared and contrasted, along with the related diagnosis of the psychological factors affecting physical condition. Guidelines for assessment of these conditions are provided, as are recommendations as to when to refer patients for further psychological and psychiatric assessment and treatment.

Hepatic microvascular dysplasia in dogs: a retrospective study of 24 cases (1987-1995)

Hepatic microvascular dysplasia (HMD) is a disease involving a microscopic shunting of blood through the liver without the presence of a macroscopic portosystemic shunt (PSS). Data was collected from medical records and telephone conversations with referring veterinarians and owners of 24 dogs diagnosed with HMD. Criteria for diagnosis included histopathological evidence of microvascular dysplasia on hepatic biopsy as well as surgical exploration and a normal mesenteric portogram to rule out a macroscopic PSS. Dogs with HMD frequently have less severe clinical signs and a better long-term prognosis than do those with a PSS that are managed medically.

Sialyl LewisX oligosaccharide preserves myocardial and endothelial function during cardioplegic ischemia

BACKGROUND

Neutrophil adhesion to endothelium contributes to myocardial reperfusion injury after cardiac operation. Initial neutrophil-endothelial interactions involve selectins, which bind Sialyl-LewisX on neutrophils. Blockade of selectin-mediated neutrophil-endothelial interactions with CY-1503, a synthetic analogue of Sialyl-LewisX, might reduce reperfusion injury after myocardial ischemia.

METHODS

The efficacy of CY-1503 to attenuate global myocardial reperfusion injury was assessed in isolated blood-perfused neonatal lamb hearts that had 2 hours of cold cardioplegic ischemia. CY-1503 (40 mg/L) or saline vehicle was added to blood perfusate before ischemia. Contractile function (developed pressure, dP/dt) and coronary vascular endothelial function (acetylcholine response) were assessed at base line and during reperfusion. Myocardial neutrophil accumulation was assessed by myeloperoxidase quantification.

RESULTS

Compared to controls, treatment with CY-1503 improved recovery of all indices of contractile function, preserved coronary vascular endothelial function, and reduced myocardial neutrophil accumulation.

CONCLUSIONS

In isolated neonatal lamb hearts that underwent hypothermic cardioplegic ischemia, CY-1503 administration reduced myocardial neutrophil accumulation and preserved endothelial and contractile function. Selectin blockade of leukocyte-endothelial interactions might attenuate reperfusion injury and enhance myocardial protection during cardiac surgical procedures.

Sialyl lewis oligosaccharide preserves cardiopulmonary and endothelial function after hypothermic circulatory arrest in lambs

OBJECTIVE

Neutrophil adhesion to endothelium contributes to cardiopulmonary dysfunction after cardiac surgical procedures. Initial neutrophil-endothelial interactions involve selectins, which bind carbohydrate ligands, such as sialyl-Lewis(X). Blockade of selectin-mediated neutrophil interactions with CY1503, a synthetic oligosaccharide analog of sialyl-Lewis(X), could limit neutrophil-mediated injury after cardiopulmonary bypass.

METHODS

The efficacy of CY1503 treatment was tested in a lamb model of cardiopulmonary bypass with hypothermic circulatory arrest. Neonatal lambs received CY1503 (n = 6, CPB-CY1503) or saline solution vehicle (n = 7, CPB-saline) into the pump prime before bypass and as a continuous infusion throughout reperfusion. Five lambs served as control animals for in vitro microvessel studies. Indexes of myocardial function (preload recruitable stroke work index, and rate of pressure rise) and pulmonary function (compliance, airway resistance, and arterial PO (2)) were measured before bypass and during reperfusion. The effect of CY1503 on endothelium-dependent vascular reactivity was assessed by means of in vitro pulmonary and coronary microvessel studies.

RESULTS

Myocardial function was depressed after circulatory arrest, but CY1503 preserved function near baseline (36% +/- 25% vs 99% +/- 19% of baseline at 3 hours of reperfusion). CY1503-treated animals also demonstrated improved pulmonary function during reperfusion. In vitro microvessel analysis of vascular reactivity revealed endothelial dysfunction after circulatory arrest compared with control lambs. CY1503-treated lambs (CPB-CY1503) had intact endothelial function, as demonstrated by normal vasodilatory responses to endothelium-dependent vasodilators.

CONCLUSIONS

CY1503 preserves cardiopulmonary and endothelial function after cardiopulmonary bypass and hypothermic circulatory arrest in neonatal lambs. This suggests a role for selectin-mediated, neutrophil-endothelial interactions in the inflammatory response after cardiac operations.

Cost-effective strategy for managing pressure ulcers in critical care: a prospective, non-randomised, cohort study

A prospective, clinical outcome study was undertaken in a critical care environment to provide evidence of the effectiveness of a unique pressure-relieving (PR) alternating mattress system in both the prevention and treatment of pressure ulcers in an extremely vulnerable population. In total, 160 critical care patients were recruited across five facilities within the United Kingdom. Despite the severity of the patients' condition (mean stay 8 days, mortality rate 24.7%) the incidence of new tissue damage was low (n = 6, 3.75%), predominantly superficial and occurring near to death, while 80% (n = 16/20) of pre-existing superficial ulcers healed. The study highlights the complexity of assessing differing levels of risk in this vulnerable population, where 87.5% of patients were ventilated and 93.1% were totally immobile. No correlation was found between the occurrence of pressure damage and Waterlow score, serum albumin, hypotension and the use of inotropic agents. Cost-effective patient management includes the allocation of effective resources to those patients who will benefit most. However, if complex risk assessment precludes the accurate assignment of resources, an alternative approach may be to provide a minimum, yet effective, standard of care to all patients. This strategy also avoids recourse to more costly interventions especially where there is little evidence of improved patient outcome.

Comparison of instrument-read dipsticks for albumin and creatinine in urine with visual results and quantitative methods

Three hospital sites evaluated the Bayer two-pad urine dipstick as a screening test for microalbuminuria. One pad estimates albumin concentrations between 10 and 150 mg/L, and the second estimates creatinine values between 300 and 3,000 mg/L. The Boehringer Mannheim (BMD) Micral dipstick was also compared and evaluated. The accuracy of the dipsticks was judged by comparison with cuvet-based immunonephelometry for albumin and to standard rate-Jaffe methods for creatinine; these assays were well standardized and controlled and were assumed to give accurate values. Precision of these methods and that of the dipsticks was determined by multiple assays of control materials. Visual or instrument (Clinitek 50 or 100) evaluation of the Bayer or visual checks of the BMD albumin dipstick pad with patients' urines gave clinically acceptable accuracy. The albumin/creatinine ratio from the Bayer dipsticks gave better accuracy for albumin excretion than the albumin pads alone from either manufacturer. This ratio should permit making a good estimate of the 24-hr albumin excretion in a randomly collected urine.

Recontextualizing Kenneth B. Clark: an Afrocentric perspective on the paradoxical legacy of a model psychologist-activist

Kenneth B. Clark, whose scientific and political legacy has been the subject of controversy over the years, presented as an important model of Afrocentric scientific praxis. Key characteristics of the Afrocentric scholar are outlined. Using Clark's academic and nonacademic writings as evidence, it is argued that Clark, though complex, exemplifies these characteristics. Clark's profound yet at times obscure vision of integration and his views on the role of empathy and respect in education are presented in detail. Clark's life and work are than reexamined and recast through the lens of W.E. Cross's (1971,1991) nigrescence model and the political-historical lens of the 2-phase Black social movement. It is concluded that academicians interested in promoting diversity, particularly within the social sciences, as well as psychologists looking for models of activist praxis, examine and learn from the life and work of Clark.

Analysis of the effects of increasing delivered dialysis treatment to malnourished peritoneal dialysis patients

BACKGROUND

Poor nutrition is associated with a loss of residual renal function and inferior clinical outcome in peritoneal dialysis (PD) patients. The value of increasing the PD dose in these individuals is unclear.

METHODS

An open, prospective, longitudinal, "intention to treat" study was performed on a whole PD population. All patients treated during an 18-month recruitment period underwent nutritional assessment and were defined as malnourished if they had a subjective global assessment (SGA) of B or C and were 5% or more below their desirable body weight. These patients received an intended dialysis dose increase of 25% and were reassessed after six months. Dialysis was not increased in the remaining patients, unless dictated by uremic symptoms.

RESULTS

Forty-eight of 153 patients were malnourished by the previously mentioned criteria. When compared with well-nourished PD patients, they had evidence of declining nutrition over the previous 12 months, as judged by a loss in body weight and mid-arm circumference (MAC), a reduced creatinine appearance, a reduced appetite for protein and calories, and low plasma albumin. They had been on treatment longer and had less residual renal function, resulting in significantly poorer solute clearances. Their peritoneal membrane function, plasma bicarbonate, comorbid, Karnofsky, Hospital Anxiety and Depression (HAD) scores were not different. Following intervention, their peritoneal Kt/Vurea was increased by 22.5%, and their total Kt/Vurea by 18%, because of a continued loss of residual function. There was also an increase in dialysis-derived calories. Weight and MAC stabilized after an initial deterioration, and creatinine appearance increased. There was no increase in protein intake, as judged by dietetic interview or protein nitrogen appearance. Oral calorie intake improved, as did plasma albumin after an initial decline. Both of these improvements were correlated with the achieved increase in Kt/Vurea. Objective measures of improvement (plasma albumin and protein nitrogen appearance) were significant in those patients without comorbid disease.

CONCLUSIONS

These results support the existing evidence that malnutrition is acquired on PD in those patients who lose residual renal function. It is feasible to increase the dialysis dose in these individuals without a detrimental effect, and there is evidence of a modest benefit in patients without comorbidity.

Insulin-like growth factor binding protein-4 expression is decreased by angiotensin II and thrombin in rat aortic vascular smooth muscle cells

Insulin-like growth factor-I (IGF-I) is a ubiquitous peptide that regulates cellular growth and differentiation and is involved in vascular proliferative responses. The effects of IGF-I are modulated by several IGF-I binding proteins (IGFBPs), including IGFBP-4, the main IGFBP produced by vascular smooth muscle cells (VSMCs). We have previously shown that angiotensin II (Ang II)-induced and thrombin-induced mitogenesis in VSMCs is dependent on autocrine IGF-I. In addition, we have demonstrated that IGF-I and IGFBP-4 mRNA levels are upregulated in the hypertensive aorta of abdominally coarcted rats, a high-renin hypertension model. To obtain further insight into the IGF-I system and to specifically study changes in IGFBP-4, a known inhibitor of IGF-I action, VSMCs were incubated with Ang II or thrombin. Compared with control, Ang II induced an 87+/-2% downregulation of IGFBP-4 mRNA levels at 24 hours, with a 61+/-6% decrease of IGFBP-4 levels, as determined by Western ligand blot analysis. Thrombin had the same depressor effects (87+/-2% for the mRNA levels and 61+/-3% for the protein levels). Ang II and thrombin coincubation with (125)I-IGFBP-4 in the conditioned media failed to reveal any increase in fragmentation, indicating that proteolytic cleavage of IGFBP-4 was not involved in the observed effects. Exogenous recombinant human IGFBP-4 decreased thrombin-induced DNA synthesis of human aortic VSMCs by 64%, whereas anti-IGFBP-4 antibody potentiated thrombin-induced DNA synthesis. These data suggest that downregulation of IGFBP-4 expression in VSMCs may play a critical role in vascular growth response to Ang II and thrombin in normal and diseased states, by increasing the bioavailability of IGF-I for its cell-surface receptor.

Pressure ulcers--prevention and treatment guidelines

Nurses deal with pressure ulcers on a regular basis, yet much of the research has yet to be put into practice. Lyn Phillips examines the implications of the European Pressure Ulcer Advisory Panel's new guidelines, dealing with prevention and treatment of pressure ulcers.

Preventative mental health care: accessing the target population

OBJECTIVE

Preventative approaches to mental illness are becoming a focus of clinical and research settings. To date, however, few clinical programs have been established with this primary aim. This descriptive paper summarises patterns of referral to one service providing clinical care for young people known to be at high risk of developing a psychotic illness.

METHODS AND RESULTS

A 20-month survey of referrals to the service revealed that most patients had a prolonged and circuitous route to assessment. Additionally, a lengthy time period elapsed between the onset of symptoms and initiation of help seeking.

CONCLUSIONS

Information arising from this survey may influence the development of strategies to improve access to this service and others aimed at the prevention of psychosis. Further, this information may affect the development of generalised preventative mental health services for young people.