The development of serum proteins and humoral immunity in opossum `embryos'

The development of serum proteins, immunoglobulins and the immune response was studied in opossum `embryos'. Serum proteins gradually increased from birth to 80 days of age when adult values were obtained. γM immunoglobulins were found at all stages of development but γG immunoglobulins were less regularly present. Those `embryos' which were 5 days or older at the time of immunization had an immune response to bacteriophage f2 and `embryos' 15 days or older responded to a hapten determinant, DNP. γM antibodies were most prominent but γG antibodies could also be detected in the immune response of opossum `embryos'.     

Detection of reticulo-endothelial blockade with low-dose test agent.

Blood clearance and organ extraction of a low-dose reticulo-endothelial test agent, technetium labelled tin colloid (TTC), was measured in groups of rabbits pretreated with reticulo-endothelial blocking agents. Electron microscopy and ultrastructure analysis confirmed that Kupffer cells extracted TTC. Pretreatment with silica caused reduced Kupffer cell uptake and spillover of TTC into the spleen. Pretreatment with sheep red cells caused reduced Kupffer cell uptake and reduced splenic uptake but anti-fibronectin caused only reduced splenic uptake of TTC. TTC is a suitable agent to detect alteration of reticulo-endothelial function.     

Estradiol and insulin: independent effects on eating and body weight in rats.

The effects of ovariectomy and estradiol replacement were determined in streptozotocin-diabetic female rats maintained on daily injections of protamine zinc insulin. Similar changes in food intake and body weight in these animals and in nondiabetic control animals indicate that the effects of estradiol on these measures are probably not dependent on changes in pancreatic insulin secretion. Acute and chronic insulin challenges in ovariectomized rats maintained on estradiol benzoate, nafoxidine or oil were also examined. The effects of insulin were not attenuated by prior estrogen conditioning, and there was no evidence of insulin resistance. These experiments suggest that the effects of estradiol on body weight and food intake in female rats are not dependent upon altered insulin levels nor attenuation of the effects of insulin. Estradiol may exert its influence on eating and body weight via separate and possibly more direct pathways. The data also are consistent with the suggestion that ovariectomy-induced and hypothalamic obesities are separate phenomena.     

Variable frequency trains enhance torque independent of stimulation amplitude

AIM: Variable frequency trains have been reported to enhance force of fatigued human skeletal muscle. More rapid calcium turnover and/or enhanced stiffness may be responsible for the augmented torque-time integral during surface stimulation at moderate amplitude. In contrast, it has recently been suggested that variable frequency train enhancement occurs only at low forces as a result of preferential stimulation of fast fibres and/or altered motor unit recruitment. If correct, this would limit the practical benefit of variable frequency trains. Accordingly, we tested the hypothesis that torque augmentation by variable frequency trains in fatigued skeletal muscle was independent of stimulation amplitude. METHODS: The m. quadriceps femoris of six males was stimulated with constant frequency trains (six 200-micros square waves separated by 70 ms) or variable frequency trains (first interpulse interval 5 ms) at an amplitude that initially evoked approximately 25 or approximately 50% of maximal voluntary isometric torque. RESULTS: After 180 constant frequency trains (50% duty cycle), isometric peak torque decreased approximately 63%. In fatigued muscle, variable frequency trains enhanced the torque-time integral by approximately 23% over that for constant frequency trains and this effect was independent of stimulation amplitude. This was due to greater peak torque and less slowing of rise time. CONCLUSION: These responses show that the torque-time integral can be enhanced at both moderate and high stimulation amplitudes. As such, it is suggested that neither recruitment nor preferential activation of fast muscle is responsible for the "catch-like" property that can be demonstrated in fatigued human skeletal muscle.     

Predictors of HIV Risk Among College Students: A CHAID Analysis1

SUMMARY The purpose of this study was to identify predictors of risk behaviors among college students and to determine how students differed in HIV risk practices. Participants were from six colleges and universities in a large southeastern metropolitan area. The present analysis was limited to participants who were 18 to 25 years of age; single; White, African American, or Asian; and reported initiation of sexual intercourse. The results demonstratedsignificant associations of gender and race with having sex within the past3 months, number of partners, condom use, length of time one knew one's sexual partner, substance use, and asking one's partner about sexualhistory. Using Chi-Square Automatic Interaction Detection (CHAID), the strongest predictor of condom use was noted to be gender, and the strongest predictor of number of partners was race. The findings of this study indicate that HIV risk factors vary dependingon a college student's ethnicity, gender, academic status, and substanceuse. Most importantly, African American men, particularly men who use drugs, and White and Asian men who use alcohol tend to report higher numbers of sexual partners. Females, particularly upperclass White females, and White men who do not use alcohol report infrequent condom use. These findings areuseful for health educators who have begun to recognize the importance ofconsidering the HIV risk factors of students and incorporating informationrelated to these factors into HIV prevention programs. From the results ofthis study, we have several suggestions that health educators and researchersmay want to consider when developing programs for college students: 1. Although students may not need extensive information about basic HIVfacts, they may need reinforcement of the information. In particular, students need to be made aware that lambskin condoms do not offer protection against HIV transmission. 2. Females need to be encouraged and taught the skills to negotiate theuse of and to actually use condoms. These skills need to be reinforced throughout college, particularly as women adopt other methods of birth control (i.e., the pill). 3. The general acceptance of condom use among African Americans and Asians may be a useful tool for the health educator. Promoting and reinforcingthis norm and behavior, while addressing some of the other risk factors inthese groups, may be a particularly effective approach to HIV prevention. 4. For White students whose condom use rates are lower, messages can include the use of condoms for STD and pregnancy protection. Messages for male students could include control over preventing pregnancy or sharing control for pregnancy prevention. 5. Couples often abandon using condoms when they feel they know each other “well enough.” Some guidelines for when to give up condoms might also be given to provide couples with responsible and realistic directions for minimizing their risk when choosing to engage in unprotected sex. These guidelines would include HIV testing two times at least 6 months apart, no evidence of STDs in either partner, and a commitment of both partners to a monogamous relationship. 6. When addressing the number of sexual partners as a risk factor, African American men and women may hold the greatest potential for change, given the greater likelihood of multiple partners in these groups. 7. With respect to drug and alcohol use, health educators may want to include discussions about the influence of drugs (particularly for African American students) and alcohol (particularly for White and Asian students) on inhibiting logical decision-making as it relates to sexual intercourse.     

Memnobotrins and memnoconols: novel metabolites from Memnoniella echinata

Four novel metabolites have been isolated from a rice culture of Memnoniella echinata (JS6308) by solvent extraction and radial silica chromatography. The structures were elucidated by spectroscopic techniques, and the absolute stereochemistry of memnobotrin A determined by X-ray crystallography.     

Regional myocardial motion and thickening assessed at rest by ECG-gated99mTc-MIBI emission tomography and by magnetic resonance imaging

We have validated ECG-gated emission tomography using technetium-99m methoxyisobutylisonitrile for the assessment of regional ventricular function by comparing it with cine magnetic resonance imaging (MRI). Gated tomography was performed at rest in 24 patients referred for myocardial perfusion imaging [17 males and seven females with a mean age of 58 years, nine of whom had had a previous myocardial infarction (MI)]. Scores were assigned to each of nine myocardial segments for wall motion and for thickening. Cine MRI was analysed in an identical fashion. Four out of 216 (2%) segments were uninterpretable by gated tomography because of inadequate tracer uptake. In eight patients without coronary artery disease (CAD), wall motion and thickening were normal by both methods. Gated tomography showed abnormal wall motion or thickening in all patients with previous MI and in five of seven patients with CAD but no prior MI. Association between wall motion and thickening was good (r _s=0.86). Overall, there was good agreement between gated tomography and MRI for both wall motion (178/212 segments, =0.66) and wall thickening (184/212 segments, =0.69). In segments with severely reduced perfusion, however, there was poorer agreement (=0.31). Interobserver and intraobserver agreement was high ( from 0.61 to 0.78). Thus, in patients investigated for CAD, there is good overall agreement between gated tomography and MRI but the agreement is lower in segments with severe perfusion defects.     

Prevalence of Personality Disorders Among Combat Veterans with Posttraumatic Stress Disorder

Many combat veterans with PTSD have co-occurring symptoms of other forms of psychopathology; however, there have been limited studies examining personality disorders among this population. The few extant studies typically have assessed only two or three personality disorders or examined a small sample, resulting in an incomplete picture and scope of comorbidity. This study assessed all DSM-III-R personality disorders in 107 veterans in a specialized, inpatient unit. Using the Structured Clinical Interview for DSM-III-R Personality Disorders, 79.4% of the participants were diagnosed with at least one personality disorder: 29.9% received only one diagnosis, 21.5% had two, 15.9% had three, and 12.1% had four or more. The most frequent single diagnoses were Avoidant (47.2%), Paranoid (46.2%), Obsessive-Compulsive (28.3%), and Antisocial (15.1%) personality disorders.(116B)(116B-2)(323-E112)     

Selective referral to high-volume hospitals: estimating potentially avoidable deaths

Context  Evidence exists that high-volume hospitals (HVHs) have lower mortality rates than low-volume hospitals (LVHs) for certain conditions. However, few employers, health plans, or government programs have attempted to increase the number of patients referred to HVHs. Objectives  To determine the difference in hospital mortality between HVHs and LVHs for conditions for which good quality data exist and to estimate how many deaths potentially would be avoided in California by referral to HVHs. Design, Setting, and Patients  Literature in MEDLINE, Current Contents, and FirstSearch Social Abstracts databases from January 1, 1983, to December 31, 1998, was searched using the key words hospital, outcome, mortality, volume, risk, and quality. The highest-quality study assessing the mortality-volume relationship for each given condition was identified and used to calculate odds ratios (ORs) for in-hospital mortality for LVHs vs HVHs. These ORs were then applied to the 1997 California database of hospital discharges maintained by the California Office of Statewide Health Planning and Development to estimate potentially avoidable deaths. Main Outcome Measures  Deaths that potentially could be avoided if patients with conditions for which a mortality-volume relationship had been treated at an HVH vs LVH. Results  The articles identified in the literature search were grouped by condition, and predetermined criteria were applied to choose the best article for each condition. Mortality was significantly lower at HVHs for elective abdominal aortic aneurysm repair, carotid endarterectomy, lower extremity arterial bypass surgery, coronary artery bypass surgery, coronary angioplasty, heart transplantation, pediatric cardiac surgery, pancreatic cancer surgery, esophageal cancer surgery, cerebral aneurysm surgery, and treatment of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). A total of 58,306 of 121,609 patients with these conditions were admitted to LVHs in California in 1997. After applying the calculated ORs to these patient populations, we estimated that 602 deaths (95% confidence interval, 304-830) at LVHs could be attributed to their low volume. Additional analyses were performed to take into account emergent admissions and distance traveled, but the impact of loss of continuity of care for some patients and reduction in the availability of specialists for patients remaining at LVHs could not be assessed. Conclusions  Initiatives to facilitate referral of patients to HVHs have the potential to reduce overall hospital mortality in California for the conditions identified. Additional study is needed to determine the extent to which selective referral is feasible and to examine the potential consequences of such initiatives.      

Does circumcision alter the periurethral bacterial flora?

A prospective study of 25 boys who underwent circumcision for medical reason was performed. Specimens of periurethral bacterial flora were taken before operation as well as 3 weeks after surgery, so that each boy acted as his own control. Before circumcision, 13 (52%) harboured uropathogenic organisms (Escherichia coli and other coliforms, Enterococcus spp, Proteus spp, Pseudomonas spp, and Klebsiella spp); after circumcision, none of the boys had uropathogens, the only organisms cultured from the periurethral region being skin commensals. We postulate that circumcision converts a ‘cul-de-sac' that is a reservoir of organisms capable of causing ascending urinary tract infection into a surface colonised by natural skin organisms. This study provides circumstantial evidence supporting the idea that circumcision in well-selected patients may confer protection from urine infection. Accepted: 15 March 1997