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Biomedical subjects

E Singer

Publications and source records attributed to E Singer.

At least 19 recordsLinked to original sources
PubMed1997

Metabolite abnormalities in progressive multifocal leukoencephalopathy by proton magnetic resonance spectroscopy.

OBJECTIVE: To evaluate progressive multifocal leukoencephalopathy (PML) lesions using proton magnetic resonance spectroscopy (1H MRS). DESIGN: CSF polymerase chain reaction (PCR) detection for JC viral (JCV) DNA; MRI and localized 1H MRS in the PML lesions, normal-appearing contralateral brain regions (CONTRA), and in matched brain regions of normal subjects. SETTING: University-affiliated medical center. PATIENTS OR PARTICIPANTS: 20 AIDS patients with clinical diagnosis of PML, 16 had tissue and/or CSF evidence of JCV infection; 20 age-matched normal subjects. MAIN OUTCOME MEASURES: Metabolites from 1H MRS: N-acetyl aspartate (NA), creatine (CR), choline-containing compounds (CHO), myoinositol (MI), glutamine/glutamate (GLX), lactate, and lipids. RESULTS: CSF PCR for JCV DNA showed 86% sensitivity. MRI showed characteristic demyelinating lesions; commonest locations were frontal lobe and cerebellum. 1H MRS in the lesions showed decreased NA (-35%; p < 0.0001) and CR (-18%; p = 0.003), increased CHO (+28%; p = 0.0005), occasional increased MI, and excess lactate (15/20 lesions) and lipids (18/20). In the CONTRA, MRS showed trends for increased CR (+15%), CHO (+15%), MI (+13%), and lower GLX (-9%; p = 0.02). Six patients, studied longitudinally (4-18 months), showed progressive spectroscopic changes; two patients with longest survival showed the highest MI. CONCLUSIONS: These MRS findings are consistent with neuropathologic observations of neuronal loss, cell membrane and myelin breakdown, and increased glial activity in PML lesions. The CONTRA abnormalities may be due to remote effects of PML or direct HIV-1 infection. 1H MRS may be useful for characterization and follow-up evaluation of PML lesions.

Adult↗
PubMed1996

Modulation of hepatic encephalopathy in rats with thioacetamide-induced acute liver failure by serotonin antagonists.

OBJECTIVE: Accumulated neurochemical data in different animal models of fulminant hepatic failure and in humans with hepatic encephalopathy suggest that serotoninergic tone is increased in the brain in hepatic encephalopathy. Since neurochemical alterations may not have behavioural or electrophysiological consequences the contribution of the serotoninergic system to the pathogenesis of hepatic encephalopathy was explored. METHODS: The effects of drugs modulating serotoninergic neurotransmission, the nonselective serotonin receptor antagonist methysergide and the serotonin2 receptor antagonist seganserin were tested neuropharmacologically in thioacetamide-induced acute liver failure in rats. RESULTS: Methysergide had no effect in control rats, but dose dependently increased motor activity in stage II-III hepatic encephalopathy by 232% (5 mg/kg methysergide), 531% (10 mg/kg) and 507% (20 mg/kg). In contrast, seganserin had no effect in encephalopathic rats. CONCLUSION: It is suggested that the beneficial effects of methysergide are serotonin, receptor mediated. Overall the results suggest that serotoninergic mechanisms contribute to some of the behavioural manifestations of hepatic encephalopathy in this animal model.

Animals↗
PubMed1995

Comparison of arterial potassium and ventilatory dynamics during sinusoidal work rate variation in man.

1. The mechanisms underlying the exercise hyperpnoea have been difficult to define. Recently it has been suggested that exercise ventilation (VE) changes in proportion to changes in arterial potassium concentration ([K+]a). Similar VE and [K+]a time courses following work rate changes have been cited as supporting evidence. This study compared [K+]a and VE dynamics during moderate exercise in man. 2. We observed VE and gas exchange responses in five healthy men to sinusoidal work rate variation between 25 and approximately 105 W. Tests of approximately 30 min duration were performed at sinusoidal periods of 9, 6 and 3 min and in the steady state. In each test, during two or three sine periods, arterial blood was sampled (24 per test) and analysed for [K+] and blood gases. Response amplitude and phase (relative to work rate) were determined for each variable. 3. [K+]a fluctuated in response to sinusoidal work rate forcing with mean-to-peak amplitude averaging 0.15 mmol 1(-1). However, among tests, VE amplitude and phase were not highly correlated with [K+]a (r = 0.36 and 0.67, respectively). Further, average [K+]a amplitude in the 9 and 6 min sinusoidal studies tended to exceed the steady-state amplitude, while average VE amplitude fell progressively with increasing forcing frequency. The dissimilar dynamics of [K+]a and VE seem inconsistent with a major role for [K+]a as a proportional controller of ventilation during non-steady state moderate exercise in man. 4. Among tests, VE and CO2 output (VCO2) amplitude and phase were closely correlated (r = 0.87 and 0.94, respectively). Further, arterial CO2 pressure (Pa,CO2) and arterial pH(pHa) did not fluctuate significantly in ten of twenty and thirteen of twenty studies, respectively. In tests where sinusoidal fluctuation was detected, amplitude averaged 1.1 mmHg and 0.008 units, respectively. Thus VE demonstrated a close dynamic coupling to CO2 output, with consequent tight regulation of Pa,CO2 and pHa.

Adult↗
PubMed1995

A randomized trial of an education and support program for HIV-infected individuals.

OBJECTIVES: To assess the effectiveness of an intervention for providing information and support to HIV-positive donors on changes in their sexual behavior, and to assess which donor characteristics are predictive of behavior change. DESIGN: Subjects were randomly assigned to a structured intervention or community referral group. Follow-up assessments were conducted every 6 months. SETTING: New York City, New York, USA. PARTICIPANTS: A cohort of 271 HIV-infected persons who donated blood to the New York Blood Center. INTERVENTION: Donors randomized to the structured intervention program met individually with a nurse for counseling and were offered a six-session support group. The program was designed to provide information, encourage safer sexual behavior and provide support. MAIN OUTCOME MEASURES: Sexual behavior, psychological distress and psychological help seeking, and immune function. RESULTS: In both groups there was a large decrease over time in reports of unsafe sexual activity. However, more than 30% of participants in both groups reported unsafe sexual activity at the 1-year follow-up visit. Donors randomized to the structured intervention program did not report significantly more behavior change at the 1-year follow-up. CONCLUSIONS: Better programs to promote behavior change in seropositive individuals are needed.

Adult↗
PubMed1994

Crystallization and preliminary structural studies of neurotrophin-3.

Neurotrophin-3 (NT-3) has been crystallized in 2 forms. Orthorhombic crystals, space group P2(1)2(1)2, diffracted to 2.8 A and have cell dimensions a = 39.1 A, b = 54.0 A, and c = 65.5 A. The second form is space group P4(3)2(1)2, with cell dimensions a = b = 67.1 A, and c = 107.9 A. The tetragonal crystals diffract to 2.8 A at room temperature and 2.5 A at -100 degrees C. The unit cell dimensions change significantly upon freezing, a = b = 66.1 A, and c = 102.8 A. Phases for the orthorhombic form were obtained by molecular replacement using nerve growth factor as the search model. A partially refined model of the NT-3 dimer (75% complete) was then oriented and positioned in the tetragonal cell.

Chemical Phenomena↗
PubMed1993

Depressive symptoms in blood donors notified of HIV infection.

OBJECTIVES: Understanding more about the psychological state of persons notified of human immunodeficiency virus (HIV) infection is critical for designing notification and counseling programs that will have the most positive effect. METHODS: The subjects were blood donors who had been notified of HIV infection by the New York Blood Center. A nurse elicited a medical history, performed a limited medical examination, and asked the subjects to complete a questionnaire that included questions about drug use, sexual behavior, and psychological characteristics. The subjects completed another questionnaire approximately 2 weeks later. RESULTS: The average depressive symptom scores for both men and women were substantially higher than scores typically found in representative population samples. More than a quarter of the men and more than a third of the women reported seeking psychological or psychiatric services in the first few weeks following notification. CONCLUSIONS: Anticipating and meeting individuals' psychological needs may be necessary if HIV screening programs are to address effectively the needs of persons infected with HIV.

Adaptation, Psychological↗
PubMed1991

Behavior changes after notification of HIV infection.

BACKGROUND: To learn more about how people who did not volunteer for testing react to information about HIV infection, we assessed short-term behavior changes in HIV-positive blood donors. METHODS: Blood donors who were notified at the New York Blood Center that they were HIV positive were asked to participate in a study. A nurse elicited a medical history, performed a limited medical examination, and asked participants to complete a questionnaire that included questions about drug use, sexual behavior, and psychological characteristics. Participants were asked to return in 2 weeks to complete another questionnaire. RESULTS: Many fewer men and women reported engaging in unsafe sexual behaviors in the 2 weeks preceding the follow-up visit than had reported such behaviors prior to notification. These changes were greater than those other investigators have reported, but about 40% of the participants still reported unsafe sexual activity at the follow-up interview. CONCLUSIONS: To make nonvolunteer screening programs for HIV infection more effective in reducing the spread of HIV infection, we need to learn more about how to help people change their high-risk behaviors.

Adolescent↗
PubMed1991

Trends in sociodemographic and behavioral characteristics of HIV antibody-positive blood donors.

This paper describes the sociodemographic characteristics of people who donated blood to the New York Blood Center between April 1985 and February 1988 and tested positive for antibodies to HIV. Information on HIV-related risk factors and knowledge of blood screening is presented for seropositive donors who participated in an evaluation study. The most commonly reported risk factor among men was sexual contact with another man, and many of the male seropositive donors reported sex with an intravenous (IV) drug user or use of IV drugs. The proportion of men reporting sexual contact with another man decreased over the period of the study, and the proportion reporting use of IV drugs or sex with an IV drug user increased. Awareness of blood screening for HIV antibodies increased over the study period. The greatest increase was among those donating for transfusion, but only about a quarter of seropositive donors used the confidential unit exclusion (CUE) process.

Adolescent↗
PubMed1989

Comparison of human papillomavirus type 1 serotyping by monoclonal antibodies with genotyping by in situ hybridization of plantar warts.

Thirty plantar warts were analyzed for the presence of HPV-1 type-specific and PV genus-specific capsid antigens by immunofluorescence (IF) using monoclonal and polyclonal antibodies and type-specific HPV-1 DNA employing in situ hybridization methods. Fifteen of 30 plantar warts were positive by IF for PV genus-specific structural viral antigens. Thirteen of the 15 productively infected plantar warts expressed intranuclear HPV-1 type-specific capsid antigens and viral DNA, which were detected in the same distribution in each individual wart. The 2 productively infected plantar warts that did not react with HPV-1 type-specific MoAbs did not react with HPV-1 type-specific DNA by in situ hybridization. Thus, serotyping of HPV-1 capsid antigens by monoclonal antibodies is concordant with genotyping of HPV-1 viral DNA by in situ hybridization in productively infected plantar warts.

Antibodies, Monoclonal↗
PubMed1988

Sociodemographic and behavioral characteristics of HIV antibody-positive blood donors.

This paper describes the sociodemographic and behavioral characteristics of 173 blood donors who were confirmed by Western blot tests to have antibodies to human immunodeficiency virus (HIV), the etiologic agent for acquired immunodeficiency syndrome (AIDS). Seropositive donors were predominantly young, unmarried, and male, and major risk factors could be identified for almost all donors. However, more than 20 per cent of the study participants were women, and many participants were not aware that they were at risk of infection. The heterogeneity of the study population, the lack of awareness among many subjects of risk factors and self-exclusion procedures, and the high level of distress among many subjects after notification, emphasize the need for intensive, well-designed education and support programs.

Adult↗
PubMed1986

Health education about AIDS among seropositive blood donors.

The New York Blood Center is developing a health education and psychosocial support program for blood donors who are notified that they are HIV antibody positive. The goals of that program are: to provide accurate and intelligible information about the test results to notified donors; to encourage behavior that will reduce the likelihood of spreading the virus; to encourage notified donors to behave in ways that will reduce the probability that they will develop AIDS; and to provide support and facilitate functional coping responses. This article reviews the theoretical and empirical work which informs the intervention program, and it describes how the program is being implemented.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Angiotensin-induced hypertension in conscious dogs: biochemical parameters and baroreceptor reflex.

The effects of a continuous iv infusion (osmotic minipumps) of angiotensin II (80 ng . kg-1 . min-1) and isoprenaline (10 ng . kg-1 . min-1) lasting 28 days were studied in six normotensive, conscious dogs. The parameters measured were systolic and diastolic blood pressure, heart rate, levels of angiotensin II, renin activity, aldosterone and antidiuretic hormone in plasma, baroreceptor reflex sensitivity and body weight. The treatment resulted in an approximately sevenfold increase in plasma angiotensin II level from 62.9 +/- 24.5 pg . ml-1 to 455.3 +/- 95.6 pg . ml-1. Systolic and diastolic blood pressure, measured for the first time 2 days after implanting the minipumps, were markedly increased throughout the infusion period (pretreatment value: 123.8 +/- 5.3/68.3 +/- 3.8 mmHg; after 2 days: 159.8 +/- 12.0/100.5 +/- 9.8 mmHg; after 28 days: 159.8 +/- 7.1/98.3 +/- 6.4 mmHg, whereas the heart rate remained unchanged due to the combined effects of angiotensin II and the concomitantly given isoprenaline. A high correlation was found between angiotensin II level in plasma and mean arterial blood pressure (r = 0.846; p less than 0.001). Furthermore, plasma renin activity was markedly suppressed by the treatment, and aldosterone levels rose. Plasma antidiuretic hormone levels were found to be unchanged at the chosen sampling time. A decrease in baroreceptor reflex sensitivity accompanied the development of the hypertensive state. There was also a loss of body weight during the infusion of angiotensin II and isoprenaline. The data provide evidence for the usefulness of the presented experimental protocol as an alternative model of arterial hypertension in chronically instrumented, conscious dogs.

Aldosterone↗
PubMed1984

[Interaction of the neuropeptides substance P and neurotensin with central monoamine transmitter systems].

In the present paper, findings on two neuropeptides, substance P (SP) and neurotensin (NT), are presented and discussed with respect to a neuromodulatory role of these peptides on brain monoamine transmitter systems. Substance P: In view of the close morphological relationship of serotonin-(5-HT-) and SP-neurons in the brainstem of the rat the effect of SP was studied in vitro on the field stimulated release of 3H-5-HT from slices of medulla oblongata. Substance P enhanced the electrically induced release of 3H-5-HT without affecting the basal release. Furthermore, the immunohistochemical evidence for the coexistence of SP and 5-HT in neurons of this area was corroborated by employing neurochemical lesioning techniques. Neurotensin: Binding sites for NT in the substantia nigra and the ventral tegmentum of the rat were decreased after stereotaxic injection of the neurotoxin 6-hydroxydopamine, which specifically destroys catecholamine-containing neurons. The results indicate a localization of NT-receptors on dopaminergic neurons in these regions. In the striatum and the nucleus accumbens, the field stimulated release of 3H-dopamine in vitro was markedly and dose-dependently increased in the presence of NT, demonstrating a direct effect of the peptide on dopamine-containing nerve terminals. In the medial preoptic nucleus, a high density of NT-binding sites was measured and stereotaxically microinjected NT caused a rise in plasma levels of luteinizing hormone (LH). Concomitantly, noradrenaline levels in the injected region were significantly reduced. The results favour an interaction of NT and noradrenergic neurons in the hypothalamic control of LH secretion.

Animals↗