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Biomedical subjects

A Levin

Publications and source records attributed to A Levin.

At least 109 records · Page 6Linked to original sources
PubMed1996

Determination of T-lymphocyte subsets on site in rural Tanzania: results in HIV-1 infected and non-infected individuals.

With the FACSCount flow cytometer, counts of CD4, CD8 and CD3 lymphocytes and CD4/CD8 ratios were performed in a rural hospital in Tanzania. A total of 168 subjects (21 HIV-1 seropositive and 147 HIV-1 seronegative) were tested as part of a population-based serosurvey and AIDS education programme; 134 other subjects were hospitalized patients who had signs and symptoms suggestive of AIDS (69 HIV-1 seropositive and 65 HIV-seronegative). Mean values for the 147 HIV-1 seronegative subjects from the local population were 980 CD4 cells (95% CI 930, 1031), 598 CD8 cells (560, 635) and CD4/CD8 ratio 1.78 (1.68, 1.89). Seropositive subjects from the local population had significantly lower CD4 cell counts, higher CD8 counts and a lower CD4/CD8 ratio. CD4 cells were significantly lower and CD8 cells significantly higher in HIV-1 seropositive hospital patients compared to HIV-1 seronegative patients. However, 23 (35%) seronegative hospital patients had CD4 counts lower than 600. These results establish baseline values for the lymphocyte subsets in this population and indicate that this technique can be used in remote areas to monitor progress of HIV-infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Can a severe degree of ketoacidosis develop overnight?

Insulin-dependent diabetes mellitus in poor control, alcohol intake associated with extracellular fluid volume contraction, or hypoglycemia may each lead to an increased rate of production of ketoacids. Generally, several days of illness are required before ketoacidosis becomes severe. Two clinical examples are presented to suggest that a severe degree of ketoacidosis may develop over a short period of time, literally overnight. In both examples, there was the ingestion of a modest amount of ethanol. From a quantitative analysis of factors that may influence the rate of production and removal of ketoacids, the following were deduced. Contributing factors to the very rapid development of maximal ketoacidosis could include the absence of a lag period for the conversion of ethanol to acetyl-coenzyme A in the liver and an impaired ability of the brain and kidneys to oxidize ketoacids, especially if these ketoacids are produced very rapidly and/or if less metabolic work is performed by these organs. In special settings, ketoacidosis may develop more rapidly than is generally appreciated.

Adult↗
PubMed1996

The benefits and side effects of ramped hypertonic sodium dialysis.

The effectiveness of ramped hypertonic sodium dialysis (RHSD) is controversial because of the prevalence of side effects (weight gain and hypertension). Standard dialysis (SD) was therefore compared with RHSD in a double-blind controlled crossover trial. Eleven patients who suffered from symptoms attributable to water shifts from extracellular fluid to intracellular fluid (headaches or hangover) or extracellular-fluid volume contraction (cramps or lightheadedness) and five asymptomatic patients were enrolled in the study. RHSD was individually tailored to each patient (to minimize thirst) during a 2-wk run-in period. Patients then received RHSD and SD for a period of 3 wk in randomized sequence. Outcome measures were both objective and subjective ratings on questionnaires. Significant differences were found between the two treatments, with RHSD improving specific problems (70% of lightheadedness/cramps, 100% of headaches/hangover) versus SD. Weight gain and hypertension were not different between the two treatments despite increased thirst sensation reported by 14/16.94% of patients preferred RHSD. Long-term studies in 20 different patients demonstrated the lack of increase in blood pressure or weight gain after 3 and 6 months of therapy.

Blood Pressure↗
PubMed1995

[Benign meningioma following scalp irradiation in north African immigrants].

Many Jewish immigrants from North Africa in the late 1950s were treated with low-dose irradiation of the scalp for tinea capitis. In 2 such patients, a 47-year-old man and a 43-year-old woman, both with long histories of headaches and dizziness, meningiomas were found. There is a well-known correlation between low-dose irradiation of the scalp and development of meningioma. Therefore, in immigrants from North Africa with prolonged headaches and dizziness, there should be a careful history with regard to irradiation of the scalp and investigation to exclude meningioma.

Africa, Northern↗
PubMed1995

Prenatal diagnosis of retinal nonattachment in the Walker-Warburg syndrome.

We report on the prenatal ultrasonographic diagnosis of Walker-Warburg syndrome based on cerebral and ocular findings. The ultrasound study done at 37 weeks gestation documented hydrocephalus and retinal nonattachment consistent with this syndrome. The ability to detect retinal nonattachment prenatally may have implications for the prenatal diagnosis of other conditions which have early retinal nonattachment as one of their findings. However, it is uncertain how early in pregnancy this defect can be detected.

Abnormalities, Multiple↗
PubMed1995

Monoclonal anti-dipeptide antibodies cross-react with detyrosinated and glutamylated forms of tubulins.

Two monoclonal antibodies, GLU-1 and A1.6, raised against gamma-L-glutamyl-L-glutamic acid dipeptide (Glu-Glu) and Ca(2+)-dependent ATPase from Paramecium, respectively, recognized the dipeptide Glu-Glu sequence. Whereas the antibodies immunofluorescently stained very few, if any, cytoskeletal fibers in cultured mammalian cells, almost all interphase as well as mitotic spindle microtubules became visible after treatment of cells with carboxypeptidase A. Immunoblot analysis demonstrated intense cross-reaction of the antibodies to the alpha-tubulin subunit. alpha-Tubulin isotypes produced as fusion proteins in bacteria were labeled by both the antibodies only when the proteins did not contain a tyrosine residue at the C terminus, indicating that GLU-1 and A1.6 specifically recognize the detyrosinated form of alpha-tubulin. When microtubule protein purified from brain was probed, not only alpha-but also, to a lesser extent, beta-tubulin were revealed by the dipeptide antibodies. A synthetic tripeptide YED containing one glutamyl group linked to the second residue of the peptide via the gamma position was also recognized by the antibodies. Since this peptide sequence corresponds to the amino acid sequence of polyglutamyated class III beta isotype at amino acid position 437 to 439, it is suggested that GLU-1 and A1.6 are able to recognize the glutamylated form of beta-tubulin. These results indicate that the C-terminal Glu-Glu sequence displays strong antigenicity, and the antibodies recognize the sequence present in the C terminus of the detyrosinated form of alpha-tubulin and the glutamyl side chain of beta-tubulin. Particularly strong immunoreaction was detected with ciliary and flagellar microtubules; thus, stable axonemal microtubules appear to be rich in post-translationally modified tubulin subunits.

Animals↗
PubMed1995

DNA-based carrier detection and prenatal diagnosis of tyrosinase-negative oculocutaneous albinism (OCA1A).

We describe molecular prenatal diagnosis and carrier detection of tyrosinase-negative oculocutaneous albinism (OCA1A) in two families. In one family, we carried out DNA-based prenatal diagnosis of OCA1A. In the other family, mutation analysis and carrier detection obviated the need for prenatal diagnosis. Molecular analysis is safer and probably more accurate than fetoscopy and fetal scalp biopsy, and should become the method of first choice for prenatal diagnosis of OCA1.

Albinism, Oculocutaneous↗
PubMed1995

Mutations in the coding region of c-myc occur independently of mutations in the regulatory regions and are predominantly associated with myc/Ig translocation.

Constitutive expression of c-myc resulting from a chromosomal translocation, which juxtaposes c-myc to an immunoglobulin gene, is a pivotal lesion in Burkitt's lymphomas. This deregulated expression of c-myc is associated with mutations in the regulatory regions, i.e. the first exon and the first intron of c-myc in tumors where the chromosomal breakpoint is not itself within the regulatory region. Until recently it was widely believed that the c-myc protein in these tumors is wild type. We have demonstrated that in a fraction of Burkitt's lymphomas from Africa and from the continental USA, and in mouse plasmacytomas, the c-myc gene carries mutations in the coding region. We now show that, occasionally, such mutations are also present in multiple myelomas--tumors which do not carry translocations or amplifications of c-myc. We also show that the frequency of the c-myc coding region mutations in BL is independent of the frequency of mutations in the regulatory region. These results suggest that the mechanisms that induce missense mutations involving the coding region of c-myc may be different from those that lead to mutations in the regulatory regions.

Burkitt Lymphoma↗
PubMed1995

BK virus and a new type of JC virus excreted by HIV-1 positive patients in rural Tanzania.

HIV-1 positive patients from Tanzanian villages near Shirati were examined for urinary excretion of the human polyomaviruses JC and BK using the polymerase chain reaction (PCR). BK virus (BKV) was detected in 11 of 23 individuals tested. The BKV DNA sequences were all closely related to prototype Gardner strain and BKV (DUN). In contrast, a new type of JCV, termed Type 3 [or JCV (Shi)], was identified in seven of these same 23 individuals by comparison with Type 1 and Type 2 sequences of the VP1/intergenic/T antigen region of U.S., European and Asian strains. This suggests that JCV and BKV, although closely related, have different evolutionary histories within the African population. The six BKV regulatory regions amplified all showed the archetypal configuration. However, two of the seven JCV regulatory regions showed rearrangements: a small deletion and an inverted repeat. JCV causes a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), in about 5% of AIDS patients in Europe and the U.S.A., but only one case has been reported in Africa. Our results suggest that this rarity of PML is not due to the absence of JCV in the African population.

Adolescent↗
PubMed1995

Evidence-based recommendations for the clinical use of recombinant human erythropoietin.

In an era of increasing scrutiny regarding use of health care resources, it is critical that physicians have rational, evidence-based guidelines for treatment decisions. This review of more than 200 published papers constitutes a comprehensive approach to evaluating the current evidence regarding the clinical use of recombinant human erythropoietin therapy in renal failure patients. After this review, specific recommendations are provided regarding who should receive r-HuEPO; what the target hemoglobin should be; the best route of administration of r-HuEPO; how iron status should be evaluated and managed; and monitoring and follow-up of patients taking r-HuEPO. Throughout the article, areas for important future research are also identified.

Anemia↗
PubMed1995

Use of patient-controlled analgesia with alfentanil for extracorporeal shock wave lithotripsy.

STUDY OBJECTIVE: To compare the efficacy of patient-controlled analgesia (PCA) to physician-controlled analgesia in patients undergoing extracorporeal shock wave lithotripsy (ESWL). DESIGN: Prospective, randomized trial. SETTING: New Jersey Kidney Stone Treatment Center at Robert Wood Johnson University Hospital, New Brunswick, NJ. PATIENTS: 62 ASA I, II, and III patients undergoing ESWL. INTERVENTIONS: The control group (n = 29) received physician-controlled analgesia with continuous infusions (0.75 mcg/kg/min) and intermittent boluses (5 mcg/kg) of alfentanil. PCA patients (n = 33) initially received alfentanil 0.5 mcg/kg followed by a continuous background infusion (0.2 to 0.5 mcg/kg/min) and self-administered alfentanil (3 to 5 mcg/kg) with a 5-minute lockout period. Bolus doses and infusion rates were determined by patient comfort and cardiorespiratory response to alfentanil. MEASUREMENTS AND MAIN RESULTS: Prior to the procedure, the patients completed two questionnaires (State-Trait Anxiety Inventory and Multidimensional Health Locus of Control Scales). During ESWL, blood pressure, heart rate, respiratory rate, oxygen saturation, end-tidal CO2, and pain and sedation levels were measured at 0, 800, 1,600, 2,400, and 3,000 shock waves. The total doses of alfentanil administered were calculated. PCA patients received 31% less alfentanil than control group patients (p < 0.0001). Patients with more preoperative anxiety required larger doses of alfentanil (p < 0.05). The pain level was slightly higher in the patients receiving PCA (p > 0.05) but most patients reported either no or only mild pain. Side effects from the therapy, such as nausea and vomiting, were either not present or were mild in both groups, with one patient (3% to 4%) in each group reporting mild nausea. Both patients and urologists were very satisfied with the pain management in both groups. CONCLUSIONS: PCA is a useful alternative to physician-controlled analgesia during ESWL since it provides equivalent pain control while using less alfentanil.

Adult↗
PubMed1995

Halothane and isoflurane alter the Ca2+ binding properties of calmodulin.

BACKGROUND: Ca2+ plays an important role in signal transduction and anesthetic mechanisms. To date, no one has observed a direct effect of volatile anesthetics on a Ca(2+)-binding protein. We therefore examined the effects of halothane and isoflurane on the Ca(2+)-binding properties of bovine brain calmodulin. METHODS: The fluorescence emission of calmodulin was obtained over a range of Ca2+ concentrations (10(-7)-10(-4)M) in the presence and absence of halothane and isoflurane. The intrinsic tyrosine fluorescence of calmodulin was measured at an excitation wavelength of 280 nm and an emission wavelength of 320 nm. Fluorescence measurements were carried out in 50 mM hydroxyethylpiperazineethane sulfonic acid, 100 mM KC1, and 2 mM ethyleneglycol-bis-(beta-aminoethyl ether) tetraacetic acid at pH 7.0 and 37 degrees C. Experiments were performed in polytetrafluorethylene-sealed cuvettes so that the volatile anesthetic concentrations remained constant. The titration data were analyzed in two ways. The data were fit to the Hill equation by using nonlinear regression analysis to derive the Hill coefficient and the dissociation constant. The data were also analyzed by two-way analysis of variance with multiple comparisons to determine statistically significant effects. Volatile anesthetic concentrations were measured by gas chromatography. RESULTS: The presence of volatile anesthetics altered the Ca(2+)-binding affinity of calmodulin in a dose-dependent fashion. At 0.57% (0.25 mM) halothane and 1.7% (0.66 mM) isoflurane, the affinity of calmodulin for Ca2+ relative to control was decreased. However, at higher concentrations of both anesthetics, the affinity for Ca2+ was increased. When the volatile anesthetics were allowed to evaporate from the experimental solutions, the observed rightward shift of the calmodulin-Ca2+ binding curve for Ca2+ at low concentrations of the anesthetics returned to the control position. The leftward shift seen at high concentrations of the anesthetics was irreversible after evaporation of 8.7% (3.3 mM) isoflurane and 5.7% (2.5 mM) halothane. CONCLUSIONS: These data demonstrate a complex interaction of two hydrophobic volatile anesthetics with calmodulin. A biphasic effect was observed both for halothane and for isoflurane. Calmodulin, an EF-hand Ca(2+)-binding protein, undergoes a conformational shift when binding Ca2+, exposing several hydrophobic residues. These residues may be sites at which the anesthetics act.

Animals↗
PubMed1995

Use of the Brief Symptom Inventory to assess psychological distress in three immigrant groups.

This paper examined the internal consistency reliability of two newly developed alternate language versions of the Brief Symptom Inventory (BSI) (This is not the Bradford Somatic Inventory, which is also known as the BSI) when used with Polish and Filipino immigrants and the original versions of the BSI and its parent instrument, the Symptom Checklist 90 (SCL-90) when used with Irish immigrants; and, the theoretical and criterion related validity of the Psychoticism subscale of the BSI for Polish, Filipino, and Irish immigrants. Internal consistency estimates and triangulation of individual BSI global and subscale scores with verbal self-reports and clinical assessments demonstrated that the BSI is a relatively reliable and valid cross-cultural measure of psychological distress. However, problems with the Psychoticism subscale occurred across all three immigrant groups, which suggested that this subscale should be interpreted with caution when used with immigrants.

Acculturation↗
PubMed1995

Challenging consults: application of principles of physiology and biochemistry to the bedside. Osmotic diuresis: the importance of counting the number of osmoles excreted.

Polyuria is usually the result of a water diuresis or an osmotic diuresis. Traditionally, the assessment of the extracellular fluid (ECF) volume and the concentration of Na+ in plasma is sufficient to differentiate between the two. We present a case and our approach, which is based on calculations and quantitation of osmoles, to demonstrate the utility of this approach. A patient with diabetes mellitus, human T-cell lymphocyte virus, type 1 (HTLV-1) associated lymphoma, and hypercalcemia presented with marked ECF volume contraction and polyuria. A spot urine osmolality was 567 mOsm/kg H2O in the face of urine output of approximately 6 L/d. The initial diagnosis was an osmotic diuresis. However, a quantitative analysis revealed the enormous number of osmoles could not be accounted for physiologically. Hence, we postulated a water diuresis to be the cause of the polyuria. To confirm this hypothesis, we found that at different times during his hospitalization, the urine specific gravity ranged from 1.005 to 1.022, and urine output varied markedly over 8-h periods. Despite a plasma sodium of 147 mmol/L, the patient did not complain of thirst. Taken together, this suggested the presence of a hypothalamic lesion which caused central diabetes insipidus with variable output of antidiuretic hormone together with a blunted thirst response. Illustration of the utility of a quantitative approach to polyuria is the focus of the discussion.

Chlorides↗
PubMed1994

Stereotactic radiosurgery for glioblastoma multiforme: report of a prospective study evaluating prognostic factors and analyzing long-term survival advantage.

PURPOSE: Prospective evaluation of the toxicity and efficacy of radiosurgery with external beam radiotherapy in the management of newly diagnosed glioblastoma. METHODS AND MATERIALS: From 5/89 to 12/92, 31 out of 51 patients with glioblastoma multiforme underwent radiosurgery, in addition to 54 Gy in 1.8 Gy/fraction following biopsy (n = 12) or resection (n = 19). Eligibility required supratentorial glioblastoma, tumor not > 4 cm in > 1 axis, age > 18 years, and location > 1 cm from optic chiasm. Patient characteristics were: age 20-78 years (median = 57); 22 male, 9 female; Karnofsky score 20-90 (m = 70), and volume of 2.3-59.7 c.c. (m = 17.4). Eighteen patients were treated with 1 collimator, 5 with 2, 7 with 3, and 1 with 4; peripheral isodoses were 40-90% (m = 72.5) and minimum and maximum tumor dose ranges were 10-20 (m = 12) and 15-35 Gy (m = 18.75). Patients were followed clinically and radiographically every 8-12 weeks to analyze survival, quality of life, and toxicity. RESULTS: With a follow-up of 12-171 weeks, 8 out of 31 (26%) patients are alive. Median survival is 42 weeks. Twelve and 24-month actuarial survival are 38 and 28%. Comparison of the 2-year survival with previous Radiation Therapy Oncology Group patients was carried out using a nonparametric recursive partitioning technique and the observed vs. expected values are 28 vs. 9.7% (p < 0.05). Extent of resection and performance status were associated with improved survival in a multivariate analysis. No significant acute toxicity was encountered. Four patients (13%) developed clinically significant necrosis verified by biopsy or positron emission tomography scan at 9-59 weeks after radiosurgery. CONCLUSION: The improvement in median survival in broadly selected glioblastoma patients treated with radiosurgery is difficult to determine, but the 2-year survival may be superior. Future randomized trials of radiosurgery are recommended, and ad hoc use of this modality should be discouraged.

Adult↗
PubMed1994

Sexual behaviour survey in a rural area of northwest Tanzania.

OBJECTIVE: Little is known about variations in patterns of sexual behaviour in different countries, cultures, and subpopulations that determine the spread of HIV-1. Quantitative studies are required to improve understanding. METHODS: To assess reported patterns of sexual behaviour, we administered a standardized questionnaire to 416 men and 498 women aged 15-49 years from a rural population in northwest Tanzania. RESULTS: Reported levels of sexual activity were highest in men and among younger age groups. The number of sexual partners and number of sex acts per unit of time were strongly correlated: men reported 10 times as many lifetime partners than women. Frequency of sexual partner exchange plateaued earlier in women (by age 25 years) than in men (by age 35 years). For the great majority, age of first intercourse was 15 years or younger; older subjects were older at first intercourse and had fewer lifetime partners than younger subjects. CONCLUSIONS: This age-related pattern suggests that more recent birth cohorts have behaviour patterns that increase the risk of sexually transmitted infectious agents such as HIV. Preventive education programmes should be targeted at young adults, who adopt higher risk profiles of frequent partner exchange linked with first intercourse at an early age.

Adolescent↗
PubMed1994

The Mother-Infant unit at Tallinn Children's Hospital, Estonia: a truly baby-friendly unit.

A mother-infant neonatal unit was established in 1979 at Tallinn Children's Hospital in Estonia to provide medical and nursing care to newborn and premature babies and their mothers. Its leading principles are 24-hour care by the mother, minimal use of technology, and little contact between the baby and medical and nursing staff. The unit was based on a conceptual model of the "psychological and biological umbilicus," which proposes that this connection binds the mother and infant together during the early weeks of life. Separation of mother and baby disrupts this important tie and may have adverse consequences for both. This paper presents data comparing weight gain during the first 30 days of life for a group of 159 preterm and full-term infants who were admitted to the unit between 1988 and 1989. Eighty-seven infants were cared for by their mothers, and 72 by nurses because their mothers were unwilling or unable to stay with the infants in the hospital. The holistic, humanistic approach used in the unit represents a truly baby-friendly hospital.

Adult↗