Allopregnanolone and induction of endogenous opioid inhibition of oxytocin responses to immune stress in pregnant rats.

In virgin rats, systemic administration of interleukin (IL)-1ß (i.e. to mimic infection), increases oxytocin secretion and the firing rate of oxytocin neurones in the supraoptic nucleus (SON). However, in late pregnancy, stimulated oxytocin secretion is inhibited by an endogenous opioid mechanism, preserving the expanded neurohypophysial oxytocin stores for parturition and minimising the risk of preterm labour. Central levels of the neuroactive metabolite of progesterone, allopregnanolone, increase during pregnancy and allopregnanolone acting on GABA(A) receptors on oxytocin neurones enhances inhibitory transmission. In the present study, we tested whether allopregnanolone induces opioid inhibition of the oxytocin system in response to IL-1ß in late pregnancy. Inhibition of 5α-reductase (an allopregnanolone-synthesising enzyme) with finasteride potentiated IL-1ß-evoked oxytocin secretion in late pregnant rats, whereas allopregnanolone reduced the oxytocin response in virgin rats. IL-1ß increased the number of magnocellular neurones in the SON and paraventricular nucleus (PVN) expressing Fos (an indicator of neuronal activation) in virgin but not pregnant rats. In immunoreactive oxytocin neurones in the SON and PVN, finasteride increased IL-1ß-induced Fos expression in pregnant rats. Conversely, allopregnanolone reduced the number of magnocellular oxytocin neurones activated by IL-1ß in virgin rats. Treatment with naloxone (an opioid antagonist) greatly enhanced the oxytocin response to IL-1ß in pregnancy, and finasteride did not enhance this effect, indicating that allopregnanolone and the endogenous opioid mechanisms do not act independently. Indeed, allopregnanolone induced opioid inhibition over oxytocin responses to IL-1ß in virgin rats. Thus, in late pregnancy, allopregnanolone induces opioid inhibition over magnocellular oxytocin neurones and hence on oxytocin secretion in response to immune challenge. This mechanism will minimise the risk of preterm labour and prevent the depletion of neurohypophysial oxytocin stores, which are required for parturition.

Ecosystem impacts of three sequential hurricanes (Dennis, Floyd, and Irene) on the United States' largest lagoonal estuary, Pamlico Sound, NC.

Three sequential hurricanes, Dennis, Floyd, and Irene, affected coastal North Carolina in September and October 1999. These hurricanes inundated the region with up to 1 m of rainfall, causing 50- to 500-year flooding in the watershed of the Pamlico Sound, the largest lagoonal estuary in the United States and a key West Atlantic fisheries nursery. We investigated the ecosystem-level impacts on and responses of the Sound to the floodwater discharge. Floodwaters displaced three-fourths of the volume of the Sound, depressed salinity by a similar amount, and delivered at least half of the typical annual nitrogen load to this nitrogen-sensitive ecosystem. Organic carbon concentrations in floodwaters entering Pamlico Sound via a major tributary (the Neuse River Estuary) were at least 2-fold higher than concentrations under prefloodwater conditions. A cascading set of physical, chemical, and ecological impacts followed, including strong vertical stratification, bottom water hypoxia, a sustained increase in algal biomass, displacement of many marine organisms, and a rise in fish disease. Because of the Sound's long residence time ( approximately 1 year), we hypothesize that the effects of the short-term nutrient enrichment could prove to be multiannual. A predicted increase in the frequency of hurricane activity over the next few decades may cause longer-term biogeochemical and trophic changes in this and other estuarine and coastal habitats.

Disparate spinal and supraspinal opioid antinociceptive responses in beta-endorphin-deficient mutant mice.

The role of endogenous opioid systems in the analgesic response to exogenous opiates remains controversial. We previously reported that mice lacking the peptide neurotransmitter beta-endorphin, although unable to produce opioid-mediated stress-induced antinociception, nevertheless displayed intact antinociception after systemic administration of the exogenous opiate morphine. Morphine administered by a peripheral route can activate opioid receptors in both the spinal cord and brain. However, beta-endorphin neuronal projections are confined predominantly to supraspinal nociceptive nuclei. Therefore, we questioned whether the absence of beta-endorphin would differentially affect antinociceptive responses depending on the route of opiate administration. Time- and dose-response curves were obtained in beta-endorphin-deficient and matched wild-type C57BL/6 congenic control mice using the tail-immersion/withdrawal assay. Null mutant mice were found to be more sensitive to supraspinal (i.c.v.) injection of the micro-opioid receptor-selective agonists, morphine and D-Ala(2)-MePhe(4)-Gly-ol(5) enkephalin. In contrast, the mutant mice were less sensitive to spinal (i.t.) injection of these same drugs. Quantitative receptor autoradiography revealed no differences between genotypes in the density of mu, delta, or kappa opioid receptor binding sites in either the spinal cord or pain-relevant supraspinal areas. Thus we report that the absence of a putative endogenous ligand for the mu-opioid receptor results in opposite changes in morphine sensitivity between discrete areas of the nervous system, which are not simply caused by changes in opioid receptor expression.

Variables affecting Army physical disability processing.

This research identifies variables affecting the length of time to process a soldier through the U.S. Army Physical Disability Evaluation System (PDES). The subjects are 8,301 soldiers whose disability records were processed in fiscal year 1996. The dependent variable examined was the average number of days a soldier remains in the disability processing system. Independent variables included age, component, compensation award, Congressional involvement, gender, grade, retirement eligibility, race, length of service, formal Physical Evaluation Board (PEB), and regional PEB. Statistical analysis using linear regression and SPSS yielded an average length of stay (ALOS) of 155 days and a range of 1 to 2,052 days. The research shows that the most significant variables affecting ALOS are Congressional involvement, component, compensation, formal PEB, and regional PEB. The authors recommend a program of disability case management and increasing emphasis on transition assistance programs to reduce ALOS in the PDES.

Attempt to correlate urine arsenic excretion with clinical course during melarsoprol therapy of patients with Rhodesian trypanosomiasis.

This study enrolled 28 CNS-involved patients with Trypanosoma brucei rhodesiense at the Kenya Trypanosomiasis Research Institute (Alupe, Kenya) to examine treatment efficacy and toxicity of melarsoprol in relation to renal excretion/dose relationships. This study complied with World Health Organization treatment recommendations, initially treating with suramin followed by three courses of melarsoprol. Traced study patients had a relapse rate of 4.1%. The toxicity and crude death rate was 7.1%. Total urine arsenic output was measured between 24 and 48 hr after the last dose for each course. The range of means of total urine arsenic output between the three treatment courses was 356-511 micrograms. There was no correlation comparing melarsoprol dose, estimated creatine clearance, or urine arsenic output. Urinary pharmacokinetic parameters are not predictive of toxicity or therapeutic efficacy.

Plasmodium falciparum circumsporozoite vaccine immunogenicity and efficacy trial with natural challenge quantitation in an area of endemic human malaria of Kenya.

It has been hypothesized that antibody induced by Plasmodium falciparum circumsporozoite protein vaccine would be effective against endemic human malaria. In a malaria endemic region of Kenya, 76 volunteers, in 38 pairs sleeping adjacently, were immunized with subunit circumsporozoite protein Asn-Ala-Asn-Pro tetrapeptide repeat-pseudomonas toxin A, or hepatitis B vaccine. After quinine and doxcycycline, volunteers were followed for illness daily, parasitemia weekly, antibody, T-lymphocyte responses, and treated if indicated. Anopheles mosquitoes resting in houses were collected, and tested for P. falciparum antigen, or dissected for sporozoites and tested for blood meal ABO type and P. falciparum antigen. Vaccine was safe, with side-effects similar in both groups, and immunogenic, engendering IgG antibody as high as 600 micrograms ml-1, but did not increase the proportion of volunteers with T-lymphocyte responses. Estimation of P. falciparum challenge averaged 0.194 potentially infective Anopheles bites/volunteer/ day. Mosquito blood meals showed no difference in biting intensity between vaccine and control groups. Both groups had similar malaria-free survival curves, cumulative positive blood slides, cumulative parasites mm-3, and numbers of parasites mm-3 on first positive blood slide, during three post-vaccination observation periods. Every volunteer had P. falciparum parastemia at least once. Vaccinees had 82% and controls 89% incidences of symptomatic parasitemia (P = 0.514, efficacy 9%, statistical power 95% probability of efficacy < 50%). Vaccine-induced anti-sporozoite antibody was not protective in this study. Within designed statistical precisions the present study is in agreement with efficacy studies in Colombia, Venezuela and Tanzania.

Impact of transmission intensity and age on Plasmodium falciparum density and associated fever: implications for malaria vaccine trial design.

To facilitate design of vaccine trials, malaria was studied in 6-month- to 6-year-old Kenyans during high (HI) and low intensity transmission seasons. During 84 days after cure, exposure to infected mosquitoes was 9-fold greater in the HI group, yet incidence of P. falciparum infection was increased only 2-fold, with no age effect. The density of recurrent P. falciparum was 14-fold greater in the HI group, and there was a striking association between age and parasitemia > or = 5000/microL. Fever was the only clinical manifestation attributable to parasitemia and only when the parasite density was > or = 5000/microL. Sixty-four percent of children with > or = 20,000 parasites/microL versus 10% with 1-4999/microL were febrile when parasitemic. Recurrent P. falciparum infection as a vaccine trial end point can be studied year-round among children < or = 6 years [corrected] in western Kenya. However, high-grade parasitemia (> or = 5000 or 20,000/microL) with or without elevated temperature will be optimally studied in the high transmission season among children < 2 years.

The role of malocclusion and orthodontics in temporomandibular disorders.

The recent literature is reviewed to assess the role of the dental occlusion in the etiopathogenesis of temporomandibular disorders (TMD) and the role of orthodontic therapy in preventing and treating TMD. Little evidence was found to support occlusal factors in TMD other than lack of posterior occlusal support and anterior open bite, which may represent predisposing factors in TMD. Orthodontic therapy may not affect the risk of developing TMD and has little role in treatment.

Plasmodium falciparum incidence relative to entomologic inoculation rates at a site proposed for testing malaria vaccines in western Kenya.

Relationships between Plasmodium falciparum incidence and entomologic inoculation rates (EIRs) were determined for a 21-month period in Saradidi, western Kenya, in preparation for malaria vaccine field trials. Children, ranging in age from six months to six years and treated to clear malaria parasites, were monitored daily for up to 12 weeks to detect new malaria infections. Overall, new P. falciparum infections were detected in 77% of 809 children. The percentage of children that developed infections per two-week period averaged 34.7%, ranging from 7.3% to 90.9%. Transmission by vector populations was detected in 86.4% (38 of 44) of the two-week periods, with daily EIRs averaging 0.75 infective bites per person. Periods of intense transmission during April to August, and from November to January, coincided with seasonal rains. Relationships between daily malaria attack rates and EIRs indicated that an average of only 7.5% (1 in 13) of the sporozoite inoculations produced new infections in children. Regression analysis demonstrated that EIRs accounted for 74% of the variation in attack rates. One of the components of the EIR, the human-biting rate, alone accounted for 68% of the variation in attack rates. Thus, measurements of either the EIR or the human-biting rate can be used to predict corresponding attack rates in children. These baseline epidemiologic studies indicate that the intense transmission patterns of P. falciparum in Saradidi will provide excellent conditions for evaluating malaria vaccine efficacy.

Preparing for the downsizing and closure of Letterman Army Medical Center: a case study.

Letterman Army Medical Center (LAMC) began a phased downsizing in July 1991 which will lead to closure by June 30, 1994. An analysis of the downsizing and closure process has yielded information which can be valuable to medical treatment facility managers faced with similar challenges in the future. By review and analysis of documentation, this case study extracted and interpreted pertinent information from historical records and from personnel involved in planning for the downsizing and closure of LAMC. This study provides managers of military hospitals that are downsizing or closing with a summary of issues for planning, compiled by their relative importance, and a description of methods employed by LAMC for managing these issues.

Prevalence of serum antibody to the type-specific glycopeptidolipid antigens of Mycobacterium avium in human immunodeficiency virus-positive and -negative individuals.

An enzyme-linked immunosorbent assay was constructed by using as antigens the type-specific immunodominant glycopeptidolipids of selected serotypes of Mycobacterium avium. This assay system was used to determine the prevalence of raised antibody levels to these antigens in groups of controls, human immunodeficiency (HIV)-negative and -positive homosexual men, and HIV-negative patients with active M. avium infections as a possible indicator of potential exposure and/or colonization by M. avium in these individuals. The results indicate that while antibody levels were raised in only 2.4% of control individuals, 33% of HIV-negative homosexual men and 44% of HIV-positive patients exhibited raised levels. Moreover, further examination of the HIV-positive group revealed no correlation between antiglycopeptidolipid antibody activity and helper T cell numbers. These data indicate that exposure to M. avium is prevalent among the homosexual male population, regardless of their HIV status. Moreover, the data are suggestive that the emergence of disseminated M. avium disease in HIV-positive patients may sometimes arise from earlier colonization, rather than as a newly acquired infection during terminal immunodeficiency.

Treatment of arsenical refractory Rhodesian sleeping sickness in Kenya.

Case histories of three Rhodesian sleeping sickness patients who relapsed after Mel-B therapy are presented. Repeated Mel-B therapy was clinically effective but not curative, and all three patients subsequently relapsed again and required further treatment.

Reversible sensorineural hearing loss in a stroke patient.

A case is presented of a patient with lateral pontine stroke which resulted in a moderate unilateral sensorineural hearing loss. ABR, word recognition scores, acoustic reflexes, neurological evaluation, and CT scan were consistent with brain stem lesion. Recovery of hearing, including acoustic reflexes and word recognition ability, occurred 2 months after the stroke.

Metabolic profiling of body fluids by proton NMR: self-poisoning episodes with paracetamol (acetaminophen).

1H NMR spectra of urine and plasma from subjects who had taken paracetamol (acetaminophen) at a therapeutic dose or in self-poisoning episodes (both fatal and nonfatal) are compared. They provide convenient metabolic profiles. For overdose cases, intense resonances corresponding to high levels of both drug and endogenous metabolites are observed. The ratios of glucuronide to sulfate conjugates are unusually high in urine from overdose cases. Elevated levels of the cysteinyl and N-acetyl cysteinyl conjugates reflect increased glutathione conjugation in the liver. The observed excretion of high levels of amino acids by overdose subjects is suggestive of drug-induced hepatic damage. No resonances for drug metabolites are detected in plasma samples. However, characteristic and abnormally intense resonances for the amino acids Phe, Tyr, His, Gln, Pro, Ala, Val, Lys, Met, Ser, and Thr are indicative of severe liver failure and disruption of normal deamination and transamination processes.

1H NMR studies of urine during fasting: excretion of ketone bodies and acetylcarnitine.

High-resolution 1H NMR spectroscopy has been applied to a study of urine from five normal human subjects during a 48-h period of fasting and for 22 h thereafter. The excretion rates of all three ketone bodies (acetoacetate, 3-D-hydroxybutyrate, and acetone), acetylcarnitine, creatinine, and sarcosine during this period were measured. Parallel increases in the excretion of the ketone bodies and acetylcarnitine were observed during fasting with little change in the output of creatinine and sarcosine.

1H, 13C NMR, and electronic absorption spectroscopic studies of the interaction of cyanide with aurothiomalate.

The reaction between cyanide and aurothiomalate (Autm) has been studied by 1H and 13C NMR spectroscopy and by uv spectroscopy. At cyanide:Autm ratios greater than or equal to 2, aurocyanide, [Au(CN)2]-, is the sole product but was also produced at lower ratios. Two intermediates were also identified. These were a mixed ligand complex, [tmAuCN]-, which accounted for over 80% of the gold at a ratio of cyanide to Autm of 1, and a bisthiomalato complex, [Autm2]-, which accounted for 6.8% of the total gold at this ratio of cyanide to Autm. The formation of these complexes may be significant in the antiarthritic activity of Autm since cyanide is produced by potential target cells such as polymorphonuclear leukocytes.

A high resolution proton nuclear magnetic resonance approach to the study of hepatocyte and drug metabolism. Application to acetaminophen.

1H spin echo NMR spectra of intact hepatocytes, isolated from rat liver, showed resonances for glucose, mobile fatty acids, and +N(CH3)3 groups including choline headgroups of phosphoglycerides. Spectra from extracts of the same cells contained many more well resolved resonances due to low Mr metabolites. These included signals for free amino acids, ketone bodies, glucose, lactate, and acetate. 1H NMR spectra from suspensions of intact hepatocytes incubated with acetaminophen showed no resonances for drug metabolites, although changes in sugar resonances were observed. However, spectra of extracts from acetaminophen-treated hepatocytes contained resonances for both acetaminophen itself and its major metabolites, the glucuronide and sulfate conjugates. Results on the extent of acetaminophen metabolism as measured by 1H NMR compared well with previously reported chromatographic studies. The rate of metabolism of acetaminophen by hepatocytes was much slower in 2H2O buffer compared to H2O buffer and selective deuteration of several metabolites including the ketone bodies, glucose, and acetaminophen glucuronide was observed. The deuteration of glucose C2H appeared to be due to futile cycling of the glycolytic pathway to at least fructose 6-phosphate, and incorporation of deuterium by the enzyme phosphoglucoisomerase. This work demonstrates that 1H NMR studies of intact hepatocytes and cell extracts together can provide considerable insight into the metabolism of acetaminophen in vitro. Little pretreatment of samples is required, results can be obtained rapidly, and both normal and drug metabolites can be observed simultaneously. Similar studies should be applicable to a wide range of other drugs.