The impact of testosterone therapy on quality of life in adolescents with Duchenne muscular dystrophy

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Testosterone therapy for pubertal induction was associated with improvements in QoL.

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Physical changes during puberty played an important role.

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Low self-esteem was also a prevailing theme.

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Parent-reported QoL scores were lower than patient-reports, consistent with other literature.

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Data from this study will provide a useful foundation for future work.

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in childhood. It is associated with progressive muscle function decline and premature death. Long-term oral glucocorticoid use slows muscle weakness but is associated with several side effects including delayed puberty. This study assessed the impact of a 2-year incremental intramuscular testosterone regimen on quality of life (QoL) in a cohort of 15 adolescents with DMD. The Pediatric Quality of Life Inventory (PedsQL) Neuromuscular module was used to assess QoL and was completed by parent-child dyads. Semi-structured interviews were carried out to understand patient views on testosterone therapy. QoL scores increased in 10 of the 15 participants during treatment, with a mean total PedsQL score of 74.6 pre-treatment v 80.2 post treatment (p = 0.04). This was supported by comments in the semi-structured interviews. Parent-reported PedsQL scores were lower than their child's post treatment (p = 0.007). Testosterone therapy for pubertal induction was associated with an improvement in QoL and the observed physical changes during puberty played an important role. Low self-esteem was also a prevailing theme. This data supports the inclusion of testosterone therapy for pubertal induction as a Standard of Care.

Young's modulus and hardness of human trabecular bone with bisphosphonate treatment durations up to 20 years

Bone modulus from patients with osteoporosis treated with bisphosphonates for 1 to 20 years was analyzed. Modulus increases during the first 6 years of treatment and remains unchanged thereafter.

INTRODUCTION

Bisphosphonates are widely used for treating osteoporosis, but the relationship between treatment duration and bone quality is unclear. Since material properties partially determine bone quality, the present study quantified the relationship between human bone modulus and hardness with bisphosphonate treatment duration.

METHODS

Iliac crest bone samples from a consecutive case series of 86 osteoporotic Caucasian women continuously treated with oral bisphosphonates for 1.1-20 years were histologically evaluated to assess bone turnover and then tested using nanoindentation. Young's modulus and hardness were measured and related to bisphosphonate treatment duration by statistical modeling.

RESULTS

All bone samples had low bone turnover. Statistical models showed that with increasing bisphosphonate treatment duration, modulus and hardness increased, peaked, and plateaued. These models used quadratic terms to model modulus increases from 1 to 6 years of bisphosphonate treatment and linear terms to model modulus plateaus from 6 to 20 years of treatment. The treatment duration at which the quadratic-linear transition (join point) occurred also depended upon trabecular location. Hardness increased and peaked at 12.4 years of treatment; it remained constant for the next 7.6 years of treatment and was insensitive to trabecular location.

CONCLUSIONS

Bone modulus increases with bisphosphonate treatment durations up to 6 years, no additional modulus increases occurred after 6 years of treatment. Although hardness increased, peaked at 12.4 years and remained constant for the next 7.6 years of BP treatment, the clinical relevance of hardness remains unclear.

PICK1 inhibition of the Arp2/3 complex controls dendritic spine size and synaptic plasticity

Activity-dependent remodelling of dendritic spines is essential for neural circuit development and synaptic plasticity, but the precise molecular mechanisms that regulate this process are unclear. Activators of Arp2/3-mediated actin polymerisation are required for spine enlargement; however, during long-term depression (LTD), spines shrink via actin depolymerisation and Arp2/3 inhibitors in this process have not yet been identified. Here, we show that PICK1 regulates spine size in hippocampal neurons via inhibition of the Arp2/3 complex. PICK1 knockdown increases spine size, whereas PICK1 overexpression reduces spine size. NMDA receptor activation results in spine shrinkage, which is blocked by PICK1 knockdown or overexpression of a PICK1 mutant that cannot bind Arp2/3. Furthermore, we show that PICK1-Arp2/3 interactions are required for functional hippocampal LTD. This work demonstrates that PICK1 is a novel regulator of spine dynamics. Via Arp2/3 inhibition, PICK1 has complementary yet distinct roles during LTD to regulate AMPA receptor trafficking and spine size, and therefore functions as a crucial factor in both structural and functional plasticity.

Long-term weight-loss maintenance: a meta-analysis of US studies

BACKGROUND

Current perception is that participants of a structured weight-loss program regain all of their weight loss within 5 y.

OBJECTIVE

The objective was to examine the long-term weight-loss maintenance of individuals completing a structured weight-loss program.

DESIGN

Studies were required to 1) have been conducted in the United States, 2) have included participants in a structured weight-loss program, 3) have provided follow-up data with variance estimates for > or =2 y. Primary outcome variables were weight-loss maintenance in kilograms, weight-loss maintenance as a percentage of initial weight loss, and weight loss as a percentage of initial body weight (reduced weight).

RESULTS

Twenty-nine studies met the inclusion criteria. Successful very-low-energy diets (VLEDs) were associated with significantly greater weight-loss maintenance than were successful hypoenergetic balanced diets (HBDs) at all years of follow-up. The percentage of individuals at 4 or 5 y of follow-up for VLEDs and HBDs were 55.4% and 79.7%, respectively. The results for VLEDs and HBDs, respectively, were as follows: weight-loss maintenance, 7.1 kg (95% CI: 6.1, 8.1 kg) and 2.0 (1.5, 2.5) kg; percentage weight-loss maintenance, 29% (25%, 33%) and 17% (13%, 22%); and reduced weight, 6.6% (5.7%, 7.5%) and 2.1% (1.6%, 2.7%). Weight-loss maintenance did not differ significantly between women and men. Six studies reported that groups who exercised more had significantly greater weight-loss maintenance than did those who exercised less.

CONCLUSIONS

Five years after completing structured weight-loss programs, the average individual maintained a weight loss of >3 kg and a reduced weight of >3% of initial body weight. After VLEDs or weight loss of > or =20 kg, individuals maintained significantly more weight loss than after HBDs or weight losses of <10 kg.

A longitudinal study of nasal airway size from age 9 to age 13

In order to define nasal breathing for diagnostic purposes, reference values of normal nasal airway size in children are needed. The purpose of this study was to examine longitudinally changes in nasal airway size that occur with age. Minimum nasal cross-sectional areas of 82 children were measured by the pressure-flow technique at 1-year intervals, from age 9 through age 13. A mixed factorial ANOVA showed that the effect of age on nasal airway size was statistically significant (p<0.001) and the effect of gender was nonsignificant. Although the mean nasal size increased from 0.4 cm2 to 0.5 cm2, it also decreased at some point between 9 and 13 years. The results suggest that the adult nasal size may be reached earlier than previously reported in cross-sectional studies.

Macrophage-derived chemokine is localized to thymic medullary epithelial cells and is a chemoattractant for CD3(+), CD4(+), CD8(low) thymocytes

Macrophage-derived chemokine (MDC) is a recently identified CC chemokine that is a potent chemoattractant for dendritic cells, natural killer (NK) cells, and the Th2 subset of peripheral blood T cells. In normal tissues, MDC mRNA is expressed principally in the thymus. Immunohistochemical analysis performed on 5 human postnatal thymuses showed high MDC immunoreactivity, which was selectively localized to epithelial cells within the medulla. To examine the effects of MDC on immature T cells, we have identified cDNA clones for mouse and rat MDC. Expression of MDC in murine tissues is also highly restricted, with significant levels of mRNA found only in the thymus. Thymocytes express high-affinity binding sites for MDC (kd = 0.7 nmol/L), and, in vitro, MDC is a chemoattractant for these cells. MDC-responsive murine thymocytes express mRNA for CCR4, a recently identified receptor for MDC. Phenotypic analysis of MDC-responsive cells shows that they are enriched for a subset of double-positive cells that express high levels of CD3 and CD4 and that have reduced levels of CD8. This subset of MDC-responsive cells is consistent with the observed expression of MDC within the medulla, because more mature cells are found there. MDC may therefore play a role in the migration of T-cell subsets during development within the thymus.

Profile of human macrophage transcripts: insights into macrophage biology and identification of novel chemokines

High throughput partial sequencing of randomly selected cDNA clones has proven to be a powerful tool for examining the relative abundance of mRNAs and for the identification of novel gene products. Because of the important role played by macrophages in immune and inflammatory responses, we sequenced over 3000 randomly selected cDNA clones from a human macrophage library. These sequences represent a molecular inventory of mRNAs from macrophages and provide a catalog of highly expressed transcripts. Two of the most abundant clones encode recently identified CC chemokines. Macrophage-derived chemokine (MDC) plays a complex role in immunoregulation and is a potent chemoattractant for dendritic cells, T cells, and natural killer cells. The chemokine receptor CCR4 binds MDC with high affinity and also responds by calcium flux and chemotaxis. CCR4 has been shown to be expressed by Th2 type T cells. Recent studies also implicate MDC as a major component of the host defense against human immunodeficiency virus.

Macrophage-derived chemokine is a functional ligand for the CC chemokine receptor 4

Macrophage-derived chemokine (MDC) is a recently identified member of the CC chemokine family. MDC is not closely related to other chemokines, sharing most similarity with thymus- and activation-regulated chemokine (TARC), which contains 37% identical amino acids. Both chemokines are highly expressed in the thymus, with little expression seen in other tissues. In addition, the genes for MDC and TARC are encoded by human chromosome 16. To explore this relationship in greater detail, we have more precisely localized the MDC gene to chromosome 16q13, the same position reported for the TARC gene. We have also examined the interaction of MDC with CC chemokine receptor 4 (CCR4), recently shown to be a receptor for TARC. Using a fusion protein of MDC with secreted alkaline phosphatase, we observed high affinity binding of MDC-secreted alkaline phosphatase to CCR4-transfected L1.2 cells (Kd = 0.18 nM). MDC and TARC competed for binding to CCR4, while no binding competition was observed for six other chemokines (MCP-1, MCP-3, MCP-4, RANTES (regulated on activation normal T cell expressed and secreted), macrophage inflammatory protein-1 alpha, macrophage inflammatory protein-1 beta). MDC was tested for calcium mobilization in L1.2 cells tranfected with seven different CC chemokine receptors. MDC induced a calcium flux in CCR4-transfected cells, but other receptors did not respond to MDC. TARC, which also induced calcium mobilization in CCR4 transfectants, was unable to desensitize the response to MDC. In contrast, MDC fully desensitized a subsequent response to TARC. Both MDC and TARC functioned as chemoattractants for CCR4 transfectants, confirming that MDC is also a functional ligand for CCR4. Since MDC and TARC are both expressed in the thymus, one role for these chemokines may be to attract CCR4-bearing thymocytes in the process of T cell education and differentiation.

A novel leukointegrin, alpha d beta 2, binds preferentially to ICAM-3

The leukocyte-restricted beta 2 (CD18) integrins mediate cell adhesion in a variety of events essential for normal immune function. Despite extensive research in this field, only three members of this integrin subfamily have been described: CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), and CD11c/CD18 (p150,95). We have identified a cDNA encoding a fourth alpha chain, alpha d, that associates with CD18. The alpha d subunit is more closely related to CD11b and CD11c than to CD11a. This integrin is expressed at moderate levels on myelomonocytic cell lines and subsets of peripheral blood leukocytes, and more strongly on tissue-compartmentalized cells such as foam cells, specialized macrophages found in aortic fatty streaks that may develop into atherosclerotic lesions. The alpha d/CD18 molecule exhibits preferential recognition of ICAM-3 over ICAM-1.

Increased detection of hepatitis C virus infection in commercial plasma donors by a third-generation screening assay

BACKGROUND

Routine screening of blood donations with second-generation hepatitis hepatitis C virus (HCV) assays has substantially reduced the occurrence of posttransfusion hepatitis. However, following the development of third-generation assays, several studies indicated that these assays may identify HCV-infected individuals who are not identified by second-generation assays.

STUDY DESIGN AND METHODS

The sensitivity of a third-generation HCV enzyme-linked immunosorbent assay (ELISA-3) was compared with a second-generation ELISA (ELISA-2) in a side-by-side study of 9936 commercial blood donors. ELISA-reactive specimens were subjected to supplemental analysis by third-generation recombinant immunoblot assay and polymerase chain reaction.

RESULTS

ELISA-3 demonstrated greater sensitivity than ELISA-2, detecting 1 additional recombinant immunoblot assay-positive specimen per 2000 tested. ELISA-3 also detected 1 additional HCV-infectious polymerase chain reaction-positive unit among approximately 10,000 units screened.

CONCLUSION

The incremental sensitivity achieved with ELISA-3 can be expected to eliminate approximately 20 infectious donations per week among those made by commercial donors in the United States. In accordance with previous studies, most of the improved sensitivity of ELISA-3 derives from its increased detection of anti-c33c (NS3), rather than from the inclusion of HCV antigen NS5.

Removal of interproximal subgingival plaque by hand and automatic toothbrushes

Subgingival plaque removal at interproximal sites by automatic and hand toothbrushes was compared with control sites at which cleansing was not performed. There were 58 patients, 35 to 63 years of age, each with one hopeless tooth requiring extraction. Each patient was randomly assigned to one of four test groups: hand brush; automatic toothbrush 1; automatic toothbrush 2; and no brushing. The brushing instructions as stated by the manufacturers were demonstrated and the patient brushed the sextant containing the test tooth for 20 seconds. The level of the gingival margin was marked at each interproximal test site. The teeth were extracted and processed for SEM, and subgingival plaque was viewed at X100 and X2000 magnifications. A montage of photomicrographs of the gingival groove to the occlusal margin of the bacterial plaque at X100 magnification was made and the distance from the groove to the margin was measured. An ANOVA was performed using P = 0.05 level for significance. Due to processing difficulties, only 33 specimens were available for analysis. The average distances from the groove to the subgingival plaque front for the four test groups were 0.514, 0.132, 0.163, and 0.111 mm respectively. The maximum distance (1.5 mm) of plaque removal was greatest for the hand toothbrush. Due to the large standard deviation (0.636 compared to 0.146, 0.250, and 0.124 respectively), the hand brushing group was excluded from ANOVA. There were no statistically significant differences among the automatic toothbrushes and the no brushing control (P = 0.8393). It was concluded that a single session of oral hygiene instruction with an automatic toothbrush did not result in subgingival interproximal plaque cleansing.

Relationship of weight loss to cardiovascular risk factors in morbidly obese individuals

OBJECTIVES

This study critically examined the relationships between weight loss and changes in serum lipid and blood pressure levels.

DESIGN

Eighty morbidly obese women and men were treated with an intensive very-low-calorie diet (VLCD) and behavioral education program. Body weight and blood pressure were measured weekly. Serum lipids were measured biweekly.

RESULTS

Patients lost an average of 35.3 kg in 25.6 weeks. These values decreased significantly: fasting serum cholesterol, 15.1%; low density lipoprotein cholesterol, 17.0%; triglycerides, 14.2%; systolic blood pressure, 8.7%; and diastolic blood pressure, 10.2%. Changes in serum lipids and blood pressure were significantly (p < 0.001) correlated with baseline values and with changes in body mass index (BMI) after adjustment for baseline values. Patients maintained an average of 19.7 kg of their weight loss at the 2-year follow-up.

CONCLUSIONS

Weight reduction through a multidisciplinary VLCD program significantly reduces risk factors for cardiovascular disease; for morbidly obese individuals, improvements in risk factors were significantly and linearly related to changes in the BMI.

Meconium-stained amniotic fluid

The presence of meconium-stained amniotic fluid is a matter of importance when considering intrapartum management. Meconium-stained amniotic fluid is known to be associated with increased fetal and maternal risks, especially when fetal exposure has been extended and the fluid is concentrated. Selected primary and secondary sources are referenced in a summary that examines the implications and management of meconium-stained amniotic fluid for the newborn. The use of amnioinfusion in selected cases with oligohydramnios or meconium-stained fluid is discussed.

Postdate pregnancy update

Trends in the management of the postdate pregnancy are reviewed. An updated approach to management of the postdate pregnancy is presented. A range of research from descriptive studies to prospective, randomized clinical trials for the pregnancy exceeding term is referenced for the clinician who seeks the rationale behind current protocol for management of the pregnancy beyond 42 weeks.

Historical perspectives on law, medical malpractice, and the concept of negligence

Since the dawn of human history, the inherent morbidity and mortality of human beings has made the diagnosis and treatment of human disease a high-risk profession. The ancient risk of physical retribution against the physician has been replaced by the modern risk of economic indemnity or compensation. Monetary settlements and awards are at times so huge that they may result in personal bankruptcy and professional disgrace. This article should not discourage health care providers from continuing their pursuits, but encourage them to enhance their knowledge about how and why medical malpractice has developed. It has been intended to facilitate the "prudent practitioner" with a more thorough understanding of some of the elements of negligence that have caused concerns in the past and will certainly create new concerns as science continues to drag the law in its wake.

Prospective, randomized, controlled comparison of the effects of low-fat and low-fat plus high-fiber diets on serum lipid concentrations

Previous studies examining the hypocholesterolemic effects of high-soluble-fiber diets have not been designed to control for dietary fat intake. Serum cholesterol reductions may therefore be accounted for by differences in consumption of fat. Moderately hypercholesterolemic, nonobese, Caucasian men and women, 30-50 y old were randomly assigned to low-fat, low-fat plus high-fiber, or usual-diet groups and followed for 12 mo. At 12 mo the high-fiber group consumed significantly more soluble fiber than both the low-fat and usual-diet groups (P = 0.0063 and P = 0.0001); the high-fiber group did not differ from the low-fat group in quantity of dietary fat consumed. The high-fiber group experienced a greater average reduction (13%) in serum cholesterol than did the low-fat (9%) and usual-diet (7%) groups. After adjustment for relevant covariates, the reduction in the high-fiber group was significantly greater than that in the low-fat group (P = 0.0482). Supplementation with soluble fiber reduces serum cholesterol beyond the reduction observed with low-fat diet alone.

Using USRDS generated mortality tables to compare local ESRD mortality rates to national rates

Mortality tables of the U.S. Renal Data System allow description of national mortality rates among prevalent dialysis patients in five-year age groups and four major categories of causes of ESRD for Black and White patients. Based on these tables derived from over 50,000 deaths in dialysis patients during 1987 to 1989 a methodology is described that allows comparison of local or regional mortality rates to national rates with determination of a standardized mortality ratio and statistical significance. Since this methodology adjusts for patient age, race and cause of ESRD, it can serve as a useful tool for dialysis research and local quality assurance.

Oat bran increases serum acetate of hypercholesterolemic men

Mechanisms for the hypocholesterolemic effects of oat bran remain unclear. Soluble fibers such as oat bran are fermented in the colon to short-chain fatty acids (SCFAs), which may enter the portal vein and attenuate hepatic cholesterol synthesis. To compare effects of oat bran and wheat bran on serum SCFA concentrations, 20 hypercholesterolemic men entered a metabolic ward and received control diets for 1 wk followed by oat-bran or wheat-bran diets for 3 wk. Oat bran decreased serum cholesterol 12.8% (P less than 0.001) whereas wheat bran had no effect. Peripheral serum SCFA concentrations were measured seven times over 14 h at the end of each diet. Serum acetate values from 1200 to 2200 were significantly higher in subjects fed oat-bran vs wheat-bran diets. Peak and incremental peak acetate values were also significantly higher than control values in subjects fed oat bran but not in subjects fed wheat bran. SCFA responses may contribute to the hypocholesterolemic effects of oat bran.

A computer-based AIDS education program for nursing students

A multidisciplinary team has developed a computer-based software program for educating nursing students and other college students about six sexually transmitted diseases (STDs). The program for educating about Acquired Immune Deficiency Syndrome (AIDS) is the first of the six "Smartbooks" to be completed, using the Hypercard Expert System shell on the Macintosh computer. Information is organized within a framework known as a concept map, and the student user progresses through the program in a self-directed way by "clicking" on the portion of the concept map that is of interest. Thus, the knowledge base can be accessed in many different ways, and is not restricted to a linear format. Comparative quantitative analysis using a control program shows consistently better student retention of information presented within the program that features concept maps. Qualitative results indicate that students find the conceptually-arranged knowledge base implicitly easy to understand, "fun" to use, and interesting to explore. Educational theory suggests that the success of such a format may be related to the schematic nature of memory.

Metabolic effects of high-carbohydrate, high-fiber diets for insulin-dependent diabetic individuals

The metabolic effects of high-carbohydrate (70%), high-fiber (70 g) (HCHF) and low-carbohydrate (39%), low-fiber (10 g) (LCLF) diets were examined for 10 subjects with insulin-dependent diabetes mellitus (IDDM). After a 1-wk control period subjects on a metabolic ward were randomly allocated to HCHF or LCLF diets for 4 wk. After a 6-wk washout period subjects re-entered the metabolic ward for 4 wk on the alternate diet. Artificial-pancreas studies were performed on each diet for measurement of insulin requirements. Compared with the LCLF diet, the HCHF diet reduced basal insulin requirements (P less than 0.025), increased carbohydrate disposed of per unit insulin (P less than 0.0008), and lowered total (P less than 0.0004) and high-density-lipoprotein cholesterol (P less than 0.0013). Glycemic control and other lipid fractions did not differ significantly. These results suggest that in IDDM patients, HCHF diets enhance peripheral glucose disposal, decrease basal insulin requirements, and lower total cholesterol without altering glycemic control or triglycerides.

Laryngeal papillomas in infants and children. Relationship to maternal venereal warts

A variety of studies has been directed at establishing the association between human papillomavirus (HPV), as manifested in the adult as a sexually transmitted disease, and laryngeal papillomas found in infants and children. In spite of substantial evidence for the transmission of HPV from women to their infants during childbirth, this association remains unknown to most clinicians in the specialty areas of childbearing and pediatrics. Nurse-midwives find evidence of venereal warts in 1% to 35% (1) of their pregnant clients, depending upon the subpopulation under consideration. A potential sequela of this common gynecologic finding is the growth of papillomas in the larynx of infants who are born to these women. Such growths are not immediately apparent and may be quite difficult to diagnose when they usually become symptomatic, between the ages of two and five years. Clinical symptoms are similar to pediatric findings in croup, asthma, and common upper airway infections. Education of both clinicians and patients regarding potential risks to progeny of infected adults will serve to guide diagnostic attempts in the pediatric population.

Mumps outbreak in a highly vaccinated population

From October 1988 to April 1989, a large mumps outbreak occurred in Douglas County, Kansas. Of the 269 cases, 208 (77.3%) occurred among primary and secondary school students, of whom 203 (97.6%) had documentation of mumps vaccination. Attack rates were highest for students attending junior high school (8.0%), followed by high school (2.0%) and elementary school (0.7%). A retrospective cohort study conducted at one junior high school with an attack rate of 12.9% did not find age at vaccination or type of vaccine received (single or combined antigen) to be risk factors for vaccine failure. Students vaccinated more than 4 years before the outbreak appeared to have a higher attack rate than those vaccinated more recently (relative risk (RR) = 4.3; 95% confidence interval (CI) = 0.6, 30.0); however, this association did not exist when risk was evaluated based on number of vaccine doses received. Students who had documentation of receiving only one dose of vaccine were at greater risk than those who had received two doses (RR = 5.2; 95% CI = 1.0, 206.2). Overall, vaccine effectiveness among Douglas County junior high school students was estimated to be 83% (95% CI = 57%, 94%). These data suggest that mumps vaccine failure and the failure to vaccinate have contributed to the relative resurgence of mumps observed in the United States since 1986. The recent change in immunization policy to recommend a two-dose schedule of measles-mumps-rubella vaccine should help reduce the occurrence of mumps outbreaks in highly vaccinated populations.

Aging and endothelial barrier function in culture: effects of chronic exposure to fatty acid hydroperoxides and vitamin E

As the endothelium ages it may become more susceptible to damage by atherogenic plasma components such as toxic lipid oxidation products. Vitamin E (vit E) might prove to be anti-atherogenic by reducing oxidative injury. This study investigated the effects of age and chronic exposure to fatty acid hydroperoxides (OFA) and/or vit E on endothelial barrier function (EBF) and cell growth characteristics. Chronic exposure to 5 microM OFA for 40 passages resulted in an age-related decrease in EBF, while supplementation of OFA-treated cultures with 25 microM vit E protected against the OFA-mediated decrease in EBF, independent of cell age. Vit E treatment alone had no significant effect on EBF relative to control cultures. No changes in growth characteristics, i.e., total DNA or protein per culture, were noted, regardless of treatment, although total DNA per culture decreased with increasing culture passage. These results suggest that chronic oxidative stress decreases EBF, predisposing the artery to infiltration by blood components and subsequent atherogenesis and that vit E delays cumulative changes in EBF related to chronic OFA exposure.

Ganglioside modulation of cyclic AMP-dependent protein kinase and cyclic nucleotide phosphodiesterase in vitro

Purified cyclic AMP-dependent protein kinase (cAK) catalytic subunit phosphorylated 180-, 49-, 31-, 19-, and 14-kilodalton (kDa) proteins of rabbit sciatic nerve membranes. The ability of cAK to phosphorylate these membrane substrate proteins was inhibited by gangliosides GM1, GD1a, and GT1b with half-maximal inhibitory concentration (I50) = 7-25 microM. Neutral glycolipids and lysophosphatidylcholine were much less effective. Cyclic AMP (cAMP) kinase phosphorylation of histone IIA was inhibited by GM1, GD1a, and GT1b (I50 = 115 microM, 75 microM, and 75 microM, respectively). Inhibition by GM1 was competitive with respect to histone (Ki = 108 microM). Autophosphorylation of cAMP kinase was inhibited by GM1 (I50 = 15 microM). GT1b, GD1a, and GM1 half-maximally stimulated calmodulin-dependent cyclic nucleotide phosphodiesterase at 0.1 microM, 0.2 microM, and 0.3 microM, respectively. Although GT1b stimulated phosphodiesterase by increasing Vmax and decreasing Km (similar to calmodulin), GD1a and GM1 produced only an increase in Vmax. These results suggest that ganglioside can modulate the activity of cAMP kinase by both direct inhibition of the enzyme and indirect reduction of cAMP levels through activation of phosphodiesterase. Through these mechanisms, gangliosides may alter cAMP-dependent protein phosphorylation and cell function within the nervous system.

Characterization of receptors for VIP on pancreatic acinar cell plasma membranes using covalent cross-linking

Vasoactive intestinal peptide (VIP) receptors on guinea pig pancreatic acini differ from those on all other tissues in containing a high-affinity VIP receptor and a low-affinity VIP receptor that has a high affinity for secretin. To characterize the molecular components of these receptors, 125I-VIP was covalently cross-linked to these receptors by four different cross-linking agents: disuccinimidyl suberate, ethylene glycol bis (succinimidyl succinate), dithiobis (succinimidylpropionate), and m-maleimidobenzoyl N-hydroxysuccinimide ester. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated a single major polypeptide band of Mr 45,000 and a minor polypeptide band of Mr 30,000 were cross-linked to 125I-VIP. Covalent cross-linking only occurred when a cross-linking agent was added, was inhibited by GTP, was inhibited by VIP receptor agonists or antagonists that interact with VIP receptors, and not by other pancreatic secretagogues that interact with different receptors. For inhibiting both cross-linking and binding of 125I-VIP to the major polypeptide Mr 45,000 and the minor polypeptide Mr 30,000 components, the relative potencies were VIP greater than helodermin greater than rat growth hormone releasing factor greater than peptide histidine isoleucine greater than secretin. The apparent molecular weight of the cross-linked polypeptides were unchanged by dithiothreitol. Thus the high-affinity VIP receptor on pancreatic acinar cell membranes consists of a single major polypeptide of Mr 45,000, and this polypeptide is not a subunit of a larger disulfide-linked structure. Furthermore, either the low-affinity VIP/secretin-preferring receptor was not covalently cross-linked under the experimental conditions or it consists of a major polypeptide with the same molecular weight as the high-affinity VIP receptor.

Osteoporosis: significance, risk factors and treatment

Osteoporosis is a serious metabolic bone disorder that results in fractures of the wrist, hip and vertebrae. These fractures frequently occur with little or no trauma. Osteoporosis is seen more frequently in women than men. While the pathogenesis of osteoporosis is incompletely understood at this time, certain risk factors are emerging as important. Among the more important of these are family history, low calcium intake, early menopause and sedentary lifestyle. Other suggested risk factors include high intakes of protein, alcohol and caffeine; low body weight; exercise-induced amenorrhea; and cigarette smoking. No single therapy or combination of therapies for osteoporosis has proven to be uniformly successful. Indeed, once fractures occur, full restoration of the skeleton may not be possible. Currently, calcium, exercise and estrogen form the treatment for osteoporosis. When these conservative measures are ineffective or inadequate, treatment with fluoride, calcitonin, vitamin D or anabolic steroids may be attempted. Research to clearly identify and quantify risk factors and find an effective treatment for osteoporosis continues.

Vasoactive intestinal peptide effects on GH3 pituitary tumor cells: high affinity binding, affinity labeling, and adenylate cyclase stimulation. Comparison with peptide histidine isoleucine and growth hormone-releasing factor

The vasoactive intestinal polypeptide (VIP) receptor was characterized on the GH3 rat pituitary tumor cell line using competitive binding studies with peptides having sequence homology with VIP. Further studies investigated receptor coupling to the adenylate cyclase complex by measurement of cAMP levels. Finally, the molecular weight of the receptor was estimated by affinity labeling techniques. Studies using 125I-VIP and unlabeled competing peptides revealed a single class of high affinity binding sites with a dissociation constant (KD) of 17 +/- 2 nM (mean +/- S.E.M.) for VIP, 275 +/- 46 nM for peptide histidine isoleucine (PHI), and 1380 +/- 800 nM for human pancreatic growth hormone releasing factor (GHRF). VIP and PHI each stimulated intracellular cAMP accumulation in a dose-dependent manner; both peptides demonstrated synergism with forskolin. In contrast, GHRF neither stimulated accumulation of cAMP nor demonstrated synergism with forskolin. VIP plus PHI (1 microM each) caused no significant increase in cAMP over either VIP or PHI alone, implying that the two peptides act through the same receptor. Covalent crosslinking of 125I-VIP to its binding site using either disuccinimidyl suberate (DSS) or ethylene glycol bis(succinimidyl succinate) (EGS) was followed by SDS-PAGE and autoradiography. The result is consistent with an Mr 47 000 VIP-binding subunit comprising or being associated with the VIP receptor of GH3 pituitary tumor cells.

Vasoactive intestinal peptide and neuropeptide modulation of the immune response

Evidence is rapidly accumulating to support the existence of a neuroimmune axis. However, the precise role of individual neurotransmitters in regulating immune function remains to be elucidated. In this review we focus on the role of vasoactive intestinal peptide (VIP) in modulation of lymphocyte function. We examine its status as a neurotransmitter, including evidence for neuronal and possible extraneuronal sites of synthesis. Further, we present data to demonstrate the presence of VIP receptors in human lymphocytes and, using the Molt 4b lymphoblastic cell line as a model, show VIP-mediated activation of adenylate cyclase leading to cAMP-dependent protein kinase-mediated phosphorylation of a specific Molt protein. Finally, we discuss the functional significance of VIP receptors on lymphocytes and present a model of neuropeptide-induced inflammation with possible therapeutic applications of this exciting new field of neuroimmunology.

Cyclic AMP-dependent protein kinase in Molt 4b lymphoblasts: identification by photoaffinity labeling and activation in intact cells by vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI)

Molt 4b lymphoblasts have previously been shown to possess a single class of pharmacologically specific, high affinity receptors for vasoactive intestinal polypeptide (VIP). This study further explores the molecular basis for modulation of human lymphocyte function by VIP. Dose-dependent stimulation of adenylate cyclase was observed in Molt lymphoblasts over the range of 0.1 nM to 1 microM VIP. VIP-mediated by guanine nucleotide. Accumulation of intracellular cAMP was observed in the presence of either VIP or the diterpene, forskolin. The effects of these two agonists were synergistic. Two neuropeptides that share sequence homology with VIP were also studied; both peptide histidine isoleucine (PHI) and human pancreatic growth hormone releasing factor (1-44 GHRF) competed for 125I-VIP binding to Molt cells. PHI stimulated intracellular cAMP accumulation and demonstrated synergism with forskolin, whereas GHRF had no effect on cAMP. Photoaffinity labeling of 100,000 X G soluble proteins with 8-N3-[32P]cAMP followed by SDS gel electrophoresis demonstrated the presence of cAMP-dependent protein kinases I and II. Cyclic AMP-dependent protein kinase II predominated in the soluble fraction and was the only isozyme observed in particulate fractions. Protein phosphorylation was studied in Molt 4b cells preincubated with [32P]PO43- followed by addition of media alone, 1 microM peptide, or 10 microM forskolin. Cells were lysed and subjected to two-dimensional electrophoresis. Increased phosphorylation of a specific 41,000 Mr protein was observed after addition of forskolin, VIP, or PHI. A much lower concentration of VIP (1 nM) also caused a significant net increase in phosphorylation, which was of a lower magnitude. In contrast, no net effect on protein phosphorylation was seen with GHRF. These data demonstrate the presence of a functional VIP receptor that is linked to the G protein-adenylate cyclase complex. The demonstration of cAMP-dependent protein kinase and of VIP- and PHI-mediated protein phosphorylation in Molt 4b lymphoblasts provides evidence on a molecular level for neuropeptide modulation of human lymphocyte function.

Cyclic AMP-dependent protein kinase in Molt 4b lymphoblasts: identification by photoaffinity labeling and activation in intact cells by vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI)

Molt 4b lymphoblasts have previously been shown to possess a single class of pharmacologically specific, high affinity receptors for vasoactive intestinal polypeptide (VIP). This study further explores the molecular basis for modulation of human lymphocyte function by VIP. Dose-dependent stimulation of adenylate cyclase was observed in Molt lymphoblasts over the range of 0.1 nM to 1 microM VIP. VIP-mediated by guanine nucleotide. Accumulation of intracellular cAMP was observed in the presence of either VIP or the diterpene, forskolin. The effects of these two agonists were synergistic. Two neuropeptides that share sequence homology with VIP were also studied; both peptide histidine isoleucine (PHI) and human pancreatic growth hormone releasing factor (1-44 GHRF) competed for 125I-VIP binding to Molt cells. PHI stimulated intracellular cAMP accumulation and demonstrated synergism with forskolin, whereas GHRF had no effect on cAMP. Photoaffinity labeling of 100,000 X G soluble proteins with 8-N3-[32P]cAMP followed by SDS gel electrophoresis demonstrated the presence of cAMP-dependent protein kinases I and II. Cyclic AMP-dependent protein kinase II predominated in the soluble fraction and was the only isozyme observed in particulate fractions. Protein phosphorylation was studied in Molt 4b cells preincubated with [32P]PO43- followed by addition of media alone, 1 microM peptide, or 10 microM forskolin. Cells were lysed and subjected to two-dimensional electrophoresis. Increased phosphorylation of a specific 41,000 Mr protein was observed after addition of forskolin, VIP, or PHI. A much lower concentration of VIP (1 nM) also caused a significant net increase in phosphorylation, which was of a lower magnitude. In contrast, no net effect on protein phosphorylation was seen with GHRF. These data demonstrate the presence of a functional VIP receptor that is linked to the G protein-adenylate cyclase complex. The demonstration of cAMP-dependent protein kinase and of VIP- and PHI-mediated protein phosphorylation in Molt 4b lymphoblasts provides evidence on a molecular level for neuropeptide modulation of human lymphocyte function.

Example of a thimerosal-dependent antibody without apparent blood group specificity

A third example of a thimerosal-dependent hemagglutinin is reported. The IgG antibody reacted by antiglobulin or ficin techniques with all cells incubated in the presence of thimerosal, including iadult cells and two examples of the Rhnull phenotype. Agglutination was inhibited by excess thimerosal (5 g/dl).

A role for inhibin in the control of follicle-stimulating hormone secretion in male rats

We examined the relationship of testosterone (T) and porcine follicular fluid (pFF) in the negative feedback control of FSH and LH secretion in adult male rats. Either at the time of castration (acute) or at least 30 days after castration (chronic), we implanted T-filled Silastic capsules, which were 2 mm, 10 mm, or 30 mm long; empty capsules (30 mm) served as controls. Seven days later, we injected either 0.15 ml of pFF or saline (i.v.), decapitated the rats 6 hours later, and collected trunk blood for subsequent serum analysis of FSH, LH, and T by RIA. In the acute groups, T implants suppressed the postcastration rises in plasma FSH and LH levels in a dose-dependent manner, with only the largest implant, 30 mm, able to return them to intact levels. PFF injection significantly suppressed FSH levels in intact and acute rats but had no effect on serum LH. In chronic rats, T therapy for 7 days suppressed plasma LH levels in a dose-dependent relationship, yet did not do so to plasma FSH levels. FSH levels were significantly higher in rats with the 30 mm T implants than in intact rats, but were significantly suppressed as compared to chronic controls. PFF significantly suppressed serum FSH levels in all chronic groups with the chronic controls showing the greatest amount of suppression. We conclude that the role for inhibin in the normal control of FSH secretion is that of a secondary modulator which is superimposed on, yet independent of, the steroid feedback mechanism. At any given moment this modulation is dependent upon the secretory activity of the FSH gonadotrope.

Covalent cross-linking of vasoactive intestinal polypeptide to its receptors on intact human lymphoblasts

125I-labeled vasoactive intestinal polypeptide (125I-VIP) was covalently cross-linked with its binding sites on intact cultured human lymphoblasts by each of three bifunctional reagents: disuccinimidyl suberate (DSS), ethylene glycol bis(succinimidyl succinate) (EGS), and N-succinimidyl 6-(4'-azido-2'-nitrophenylamino) hexanoate (SANAH). A fourth cross-linking agent with a shorter chain length, N-hydroxysuccinimidyl 4-azidobenzoate (HSAB), was much less effective in cross-linking 125I-VIP to the site. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography demonstrated a band of Mr approximately equal to 50,000 +/- 3,000, regardless of which cross-linker was used. The labeling of this band was specific in that it was prevented by 10(-6) M unlabeled VIP and was partially blocked by the homologous hormones secretin and glucagon. The relative potencies of these peptides in blocking the cross-linking of 125I-VIP to the Mr approximately equal to 50,000 band of the lymphoblasts (VIP greater than secretin greater than or equal to glucagon) were similar to those previously found for competitive inhibition of 125I-VIP binding to its putative high-affinity receptor on these cells. The covalent cross-linking required a bifunctional reagent; it was dependent on both the number of Molt cells and the concentration of 125I-VIP. The apparent molecular weight of the cross-linked species was unchanged by treatment with dithiothreitol. These observations suggest that the Mr = 50,000 species represents 125I-VIP cross-linked to a specific plasma membrane receptor and that the receptor does not contain interchain disulfide bonds.

Allergens in Hymenoptera venom XI. Isolation of protein allergens from Vespula maculifrons (yellow jacket) venom

Pure Vespula maculifrons venom was demonstrated to contain five major allergenic proteins, which were all isolated from commercial venom sac extract. The five proteins: Vmacl, MW 97,000; hyaluronidase, MW 46,000; Vmac3, MW 39,000; phospholipase A and B, MW 34,000; and antigen 5, MW 22,000 were all demonstrated to be biochemically and immunologically distinct. All five proteins had significant allergenic activity, with phospholipase and hyaluronidase demonstrating the most IgE binding with 39 sera from allergic patients. Sera from honeybee-reactive patients, who had weak cross-reactions with yellow jacket venom, demonstrated strong IgE binding to purified V. maculifrons hyaluronidase and Vmacl. Dose-dependent inhibition of RAST was observed by use of honeybee hyaluronidase and high-molecular-weight fraction to inhibit the binding to the corresponding yellow jacket allergen.

Allergens in hymenoptera venoms. X. Vespid venoms versus venom sac extracts: comparison by two-dimensional polyacrylamide gel electrophoresis

Vespid venoms were compared to venom sac extracts by two-dimensional polyacrylamide gel electrophoresis using non-equilibrium pH gradient electrophoresis in the first dimension and sodium dodecyl sulfate electrophoresis in the second. The gels were stained with silver. Fresh venoms from four species, Vespula maculifrons, Polistes fuscatus fuscatus, P. metricus and P. exclamans, were compared with commercially available venom sac extracts from the same species. In each case the venom sac extract contained all of the proteins detected in the fresh venom plus numerous additional proteins which are probably sac components. Yellow jacket and bee (Apis mellifera) proteins were extracted from the gels and tested for IgE binding activity using pooled sera from RAST-positive individuals. Significant IgE binding activity was found for the five known bee allergens and for the major yellow jacket venom proteins. Fresh pure vespid venoms contain a relatively small number of major protein subunits. Venom sac extracts contain the same components plus many other proteins not found in the pure venoms.

Demonstration of IgE and IgG antibodies against venoms in the blood of victims of fatal sting anaphylaxis

Nine people died from insect sting anaphylaxis in North Carolina from 1979 to 1981. Postmortem blood specimens from eight of these subjects were analyzed for IgE and IgG antibodies against venoms. All eight were RAST positive to at least one of the venoms. IgE and IgG anti-venom levels were comparable to those of a group of untreated sting-allergic individuals. RAST to venoms was also performed on several control groups of sera and from 3% to 50% positive RAST results were found. The highest incidence was in rural North Carolina outdoor workers. The incidence of positive RAST results in the sting-death group was significantly different from that in the control groups. This is the first demonstration of IgE antibodies against venoms in the sera of victims of fatal anaphylaxis from stings and adds further evidence for the role of IgE in sting anaphylaxis.

Two-dimensional polyacrylamide gel electrophoresis of hymenoptera venom and venom sac extracts

Hymenoptera venom and venom sac extracts were studied by two-dimensional polyacrylamide gel electrophoresis using non-equilibrium pH gradient electrophoresis in the first dimension and sodium sulfate electrophoresis in the second dimension. Pure Apis mellifera (honeybee) venom collected by electrical stimulation was resolved into five major and more than 20 minor components. Polistes (paper wasp), Vespula (yellow jacket), Dolichovespula (aerial hornet) and Vespa (old world hornet) venom sac extracts contained more than 40 components each. These results illustrate the complexity of the mixtures in current use for immunotherapy for stinging insect hypersensitivity. The degrees of similarity observed between the various aspects of Polistes and Vespula studied correlate with the phylogenetic classification of these species.

Effect of vasoactive intestinal polypeptide on glycogen metabolism in rat hepatocytes

The effects of vasoactive intestinal polypeptide (VIP) on several enzymes of glycogen metabolism in rat hepatocytes were compared with those of glucagon and of vasopressin (ADH). VIP caused phosphorylase activation and glycogenolysis in hepatocytes from fed rats. In hepatocytes from fasted rats incubated with glucose, lactate, and pyruvate, VIP inhibited net glycogen deposition, inactivated glycogen synthase, and activated phosphorylase. VIP was about 100-fold less potent than glucagon and 1,000-fold less potent than ADH in causing activation of phosphorylase. The ability of VIP to activate phosphorylase was not altered by chelation of the calcium in the medium. The half maximal effective doses of VIP for both phosphorylase activation and stimulation of glycogenolysis were 10-30 nM. Treatment with VIP, ADH, or glucagon did not decrease phosphorylase phosphatase activity. Each of these hormones, however, lengthened the lag time before synthase phosphatase activity was expressed in vitro. Other gut hormones tested did not affect hepatocyte glycogen metabolism. These results do not support the concept of physiologic control of hepatic glycogen metabolism by VIP or by other gut hormones.

Effects of 6-hydroxydopamine and pimozide on temperature maintenance by the chicken

Intraventricular implants of pimozide in adult white leghorn hens were used to block dopamine (DA) receptors, and 6-hydroxydopamine (6-OHDA) was injected intraventricularly to destroy the noradrenergic system locally. The hens were exposed to ambient temperatures of 5 and 35 degrees C, and their core temperature was measured. One hundred micrograms of 6-OHDA significantly reduced the norepinephrine (NE) but not the DA content of the hypothalamus and reduced the uptake of [3H]NE but not of [3H]DA by synaptosomes in vitro. Neither of the drug treatments nor their combination affected average core body temperature (Tb) at either 5 or 35 degrees C. Pimozide treatment caused a lower maximum Tb at 35 degrees C and a higher maximum Tb at 5 degrees C than the control treatment. No evidence was obtained that 6-OHDA treatment affected body temperature regulation. It is concluded that neither the DA nor the NE system is essential for normal temperature maintenance in the hen exposed to either 5 or 35 degrees C.