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Biomedical subjects

R Burstein

Publications and source records attributed to R Burstein.

At least 73 records · Page 4Linked to original sources
PubMed1989

Retrograde labeling of neurons in spinal cord that project directly to nucleus accumbens or the septal nuclei in the rat.

Somatosensory information has been thought to ascend from the spinal cord to limbic areas of the telencephalon through indirect, multisynaptic pathways. We now report that injections of Fluoro-gold into either the nucleus accumbens or the septal nuclei labeled hundreds of neurons in the spinal cord. These and our recent anterograde tracing experiments indicate that some spinal cord neurons project directly to the telencephalon and suggest that nucleus accumbens and septal nuclei process somatosensory information.

Afferent Pathways↗
PubMed1989

The effect of caffeine ingestion on physical performance after prolonged exercise.

The purpose of this study was to determine the effect of caffeine ingestion on physical performance after prolonged endurance exercise. Twenty three trained male volunteers participated in a 40-km march and were divided into two groups, matched for caffeine clearance rate and aerobic capacity. The experimental group ingested, prior to the march, a caffeinated drink at a dose of 5 mg.kg-1 body mass and at the 3rd and 5th h of marching an additional drink at a dose of 2.5 mg.kg-1 body mass. The control group ingested a drink of equal volume at the same times. Upon termination of the march each subject performed a cycle ergometer test at an intensity of 90% maximal oxygen consumption. Time to exhaustion and rate of perceived exertion (RPE) were recorded. Blood samples were drawn predrink, at the 3rd and 5th h of marching and immediately after the cycle ergometer test, and were analysed for caffeine, free fatty acids (FFA), lactate and glucose levels. Plasma FFA levels increased during the march (p less than 0.05), with no significant difference between groups. Lactate levels increased in the experimental group (p less than 0.05), with no significant change in the control group. Glucose levels did not change significantly in either group. After the cycle ergometer test, lactate levels were significantly higher in the experimental, as compared to the control group (3.77 +/- 0.33 vs 2.52 +/- 0.35 mmol.l-1, respectively). There was no significant difference between treatments in the time to exhaustion on the cycle ergometer, but RPE was different (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Prediction of physical performance through muscle enzymes activity.

Physical performance deteriorates during strenuous exercise as manifested by a decrease in maximal aerobic power and increased activity of serum muscle enzymes. The relationship between these parameters was investigated in 41 trained subjects during 24 h marches and the following recovery period. Peak O2 uptake and serum activity of creatine phosphokinase (CPK) and glutamic oxalacetic transaminase (GOT) were measured. During the marches there was a simultaneous, significant elevation in serum CPK and GOT activity and a significant reduction in peak O2 uptake. During the early recovery period (24 h) no significant changes occurred in muscle enzyme activity and peak O2 uptake; thereafter (up to 72 h after the end of the march), a gradual decline in enzyme activity levels with a concomitant increase in peak O2 uptake was observed, reaching pre-march values. A "mirror image" relationship between muscle enzyme activity and peak O2 uptake was found during three clearly distinguished phases: a) 24 h march, b) early recovery stage and c) late recovery stage. These findings suggest that muscle enzyme leakage from muscle cells is closely related to the decline in muscular function and aerobic power. Thus, muscle enzyme activity might be a practical measure of physical performance capacity during the early and late stages of recovery from prolonged endurance exercise.

Adult↗
PubMed1988

External load can alter the energy cost of prolonged exercise.

The present study was undertaken to examine the energy cost of prolonged walking while carrying a backpack load. Six trained subjects were tested while walking for 120 min on a treadmill at a speed of 1.25 m.s-1 and 5% elevation with a well fitted backpack load of 25 and 40 kg alternately. Carrying 40 kg elicited a significantly higher (p less than 0.01) energy cost than 25 kg. Furthermore, whereas carrying 25 kg resulted in a constant energy cost, 40 kg yielded a highly significant (p less than 0.05) increase in energy cost over time. The study implies that increase in load causes physical fatigue, once work intensity is higher than 50% maximal work capacity. This is probably due to altered locomotion biomechanics which in turn lead to the increase in energy cost. Finally, the prediction model which estimates energy cost while carrying loads should be used with some caution when applied to heavy loads and long duration of exercise, since it might underestimate the actual energy cost.

Adult↗
PubMed1988

Medical management of three asymptomatic infants with severe valvar aortic stenosis.

We report on the clinical course and serial hemodynamic studies of three patients with severe valvar aortic stenosis diagnosed in the neonatal period. None of the children were symptomatic in the first year of life. In each case, a conservative initial management approach was adopted. Between the time of initial study (mean age, 1.8 months) and the follow-up at 12-27 months of age (mean, 14.3 months), mean left ventricular systolic pressure decreased from 151 to 125 mmHg, the mean peak systolic pressure gradient across the aortic valve decreased from 61 to 33 mmHg, and the mean calculated aortic valve area index increased from 0.24 to 0.60 cm2/m2. One patient was operated on for symptoms that appeared at 14 months of age. The patient followed longest is now 5 years old, is growing well, has a normal electrocardiogram and an echo-predicted left ventricular systolic pressure of 128 mmHg. This experience suggests that not all asymptomatic neonates with severe valvar aortic stenosis require surgical intervention early in life. In some, the aortic valve orifice may increase in size with somatic growth and obviate the need for surgery in infancy or early childhood.

Aortic Valve↗
PubMed1988

Isolation of HIV from Israeli patients and asymptomatic carriers.

Human immunodeficiency virus (HIV 1) strains were isolated from peripheral blood lymphocytes of eight homosexual men (two asymptomatic and six with lymphadenopathy syndrome) and of the wife of an AIDS patient with AIDS-related complex. All except one had antibodies to HIV in their serum. Virus isolation was carried out by cocultivation of the donors' peripheral lymphocytes with HUT-78 cells or with phytohemagglutinin-stimulated normal cord blood lymphocytes. Identification of the virus was based on detection of specific cytopathogenic effects, determination of reverse transcriptase activity, specific immunofluorescence and Southern blot analysis of HIV proviral DNA in the infected cell cultures.

AIDS-Related Complex↗
PubMed1988

Immune changes in male homosexuals--predisposing factors for HIV seroconversion.

Israel is still a low incidence country for AIDS and thus the temporal relationships between various cofactors and HIV infection can be more easily determined. We have studied a cohort of 243 asymptomatic male homosexuals (MHS) during the last 4 years. At the beginning of the study, 40% had significant decreases in the peripheral blood lymphoid populations, signs for reactivation of CMV and EBV infections, and elevated serum levels of interferon. There was no difference in the prevalence of these immune derangements between seropositive and seronegative individuals. In the course of 4 years' follow-up, the prevalence of these immune derangements has remained the same though being significantly more severe in the HIV seropositive subjects. HIV seroconversion did not exceed 8% (about 2% annually) and was related to the immune impairments found when first seen at the beginning of the study. The results suggest that immune impairments are common among asymptomatic MHS, precede HIV infection, and probably contribute to the increased risk for AIDS among male homosexuals.

Antibodies, Viral↗
PubMed1987

Immune impairments and antibodies to HTLVIII/LAV in asymptomatic male homosexuals in Israel: relevance to the risk of acquired immune deficiency syndrome (AIDS).

We have studied 288 Israeli asymptomatic male homosexuals (MHS) to determine the prevalence of antibodies to HTLVI and HTLVIII and their correlation with impairments of the immune system and serum interferon (IFN). Seropositivity for HTLVI, HTLVIII, or both was found in 1.4, 8.3, and 0%, respectively. Significant decreases in the total peripheral T cells, TH cells, and TH/TS ratio as well as elevated alpha IFN serum levels were found in the MHS group in comparison with normal controls. Although no difference in the prevalence of either immune derangements or elevated serum IFN was observed between HTLVIII/LAV-seropositive and HTLVIII/LAV-seronegative MHS, the decreases in total T cells, TH cells, and TH/TS ratios were significantly greater in the seropositive MHS. These results indicate that (a) immune impairments and IFN system activation occur commonly in homosexuals, precede their exposure to HTLVIII/LAV, and probably reflect this group's increased risk for AIDS and (b) HTLVIII/LAV infection of MHS aggravates further their preexisting immune impairments.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Immunoreconstitution of T-cell impairments in asymptomatic male homosexuals by thymic humoral factor (THF).

The feasibility of using Thymic Humoral Factor (THF) for immunomodulation in asymptomatic male homosexuals was evaluated in a study on fifteen subjects with T-cell impairments, selected on the basis of a 2SD reduction in T helper/inducer (T4+) cells and one additional lymphocytic defect. Following two biweekly courses of treatment, mean relative increments of T4+ (P less than 0.002), T3+ (P less than 0.02) and total lymphocyte (P less than 0.05) populations of the group receiving THF (n = 7) were significantly increased when compared to the placebo group (n = 8). In addition, a transient increase in T4+ lymphocytes was observed after the first course in the two individuals of the THF-treated group who were seropositive for HTLV-III/LAV but not in those who were seronegative. No difference was found between the groups in fluctuations of serum interferon (IFN) or proliferation of peripheral mononuclear cells to mitogens. The results of this limited trial demonstrate that THF is capable of correcting T-cell impairments that may predispose asymptomatic homosexuals to infection by HTLV-III, without affecting IFN production. These findings suggest that future strategies for AIDS prevention in high-risk groups should include institution of large controlled trials in immunodeficient, asymptomatic, HTLV-III/LAV-seronegative male homosexuals to study the potential of selective immunoreconstitution as a preventive measure against HTLV-III/LAV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Changes of white blood cell count during prolonged exercise.

Leukocytosis was postulated to accompany short- and medium-length exercise; in this report, we have studied the changes in leukocyte count during and following prolonged exercise. White blood cell (WBC) counts were obtained in 15 endurance-trained subjects before, during, and at a recovery period after an ultralong exercise (120 km march), lasting 24 h. WBC counts increased after 16 h march from a baseline value of 8.5 +/- 0.3 10(9) l-1 to 11.3 +/- 0.8 10(9) l-1 (P less than 0.05) and then declined to 7.1 +/- 0.9 10(9) l-1 after 24 h march with no further significant changes during 64 h of recovery. These observations were supported by previous findings in three separate marches performed by a second group (40, 70, and 120 km). A parallel increase in plasma creatine phosphokinase activity from 127 +/- 4.4 ul-1 to 539 +/- 106.3 ul-1 was observed after 16 h march (P less than 0.01), indicating muscle cell damage. Our findings suggest that in extremely long marches, WBC counts return to baseline values before exercise is terminated. This phenomenon may reflect WBC infiltration to damaged muscle tissue.

Adult↗
PubMed1987

Systemic oxygen transport in patients with congenital heart disease.

The physiology of oxygen delivery was studied in 118 stable patients from 3 months to 20 years old with congenital heart disease. During cardiac catheterization, oxygen consumption (VO2), arterial and venous blood gases and oxygen saturations (range 41% to 98%), hemoglobin concentration, diphosphoglycerate (2,3-DPG), and P50 levels were measured, and then cardiac output, systemic oxygen transport (SOT), arterial and venous oxygen contents, and the VO2/SOT ratio (fractional O2 extraction) were calculated. P50 averaged 31 mm Hg, compared with 27 mm Hg in 10 control children (p less than .01). The composite O2-hemoglobin dissociation curve in vivo was broad: Po2 varied from 37 to 65 mm Hg at 80% saturation. P50, 2,3-DPG, hemoglobin concentrations, and O2 saturation varied widely and inconsistently with Po2 and arterial and venous O2 content, but resulted in clustering of the arterial oxygen content near 165 +/- 23 (SD) ml/liter over a wide range of Po2 and hemoglobin concentrations. SOT varied in direct relation with flow (r = .82, p less than .001), but not with oxygen content, Po2, or P50. VO2 varied widely at normal or high levels of SOT, but decreased linearly at SOT levels below 400 ml/min/m2. Oxygen extraction varied inversely with venous O2 content, rising to about 50% and plateauing below venous contents of 100 ml/liter. O2 extraction did not correlate with Po2, arterial O2 content, or P50. These data suggest that: O2 saturation cannot be predicted or calculated accurately from measured Po2, but must be measured directly, 2,3-DPG, hemoglobin concentration, and P50 fluctuate to stabilize arterial oxygen content, SOT is determined primarily by cardiac output in subjects who are adapted chronically, O2 extraction rises, due to a fall in venous O2 content, to maintain VO2 as transport falls, below a critical level of SOT, O2 extraction ceases to rise and VO2 falls with further reduction in transport.

2,3-Diphosphoglycerate↗
PubMed1987

Direct somatosensory projections from the spinal cord to the hypothalamus and telencephalon.

Somatosensory input to the hypothalamus has been thought to ascend via an indirect, multisynaptic pathway. However, we have antidromically identified nociceptive spinal cord neurons that project directly to the lateral hypothalamus in rats. Retrograde tracers injected into the lateral hypothalamus labeled many spinal neurons bilaterally within the marginal zone, the lateral reticulated area, the lateral spinal nucleus, and the area surrounding the central canal. An anterograde tracer injected into these areas of the spinal cord labeled fibers and terminals in the lateral hypothalamus and, surprisingly, in a number of telencephalic areas. These findings demonstrate a direct somatosensory projection from the spinal cord to the hypothalamus and several telencephalic regions.

Animals↗
PubMed1985

Sensitivity of Capnocytophaga species to bactericidal properties of human serum.

Capnocytophaga is a newly described genus of gram-negative bacteria which can cause serious oral and extraoral infections in the susceptible host. In the present study, sensitivity of Capnocytophaga spp. to the bactericidal properties of human serum was investigated. Laboratory strains representative of Capnocytophaga sputigena, C. ochracea, and C. gingivalis and seven oral isolates of Capnocytophaga spp. obtained in primary culture were determined to be sensitive to killing by pooled normal serum. In contrast, little or no killing of Capnocytophaga spp. was observed when these organisms were incubated in the presence of hypogammaglobulinemic serum despite evidence for alternative pathway activation. However, hypogammaglobulinemic serum could be reconstituted to bactericidal activity by the addition of the immunoglobulin M fraction of normal serum. Capnocytophaga spp. failed to activate the classical pathway in hypogammaglobulinemic serum, thus ruling out an antibody-independent mechanism of killing. In contrast, good correlation was observed between serum-mediated killing and antibody-dependent classical pathway consumption. These results indicate that complement in the presence of bactericidal antibody may be an important determinant of host resistance to intra- and extraoral infections caused by Capnocytophaga spp.

Adult↗
PubMed1985

Acute reversal of the enhanced insulin action in trained athletes. Association with insulin receptor changes.

We studied the effect of aerobic training and detraining on insulin-stimulated glucose disposal and on erythrocyte insulin receptor binding. Seven endurance-trained athletes were studied at 12 h, 60 h, and 7 days after cessation of training and compared with three untrained, age- and weight-matched controls. The metabolic clearance rate of glucose as measured by the euglycemic clamp technique was 15.6 +/- 1.8 ml/kg/min (mean +/- SEM) in the trained subjects 12 h after the last bout of exercise compared with 7.8 +/- 1.2 ml/kg/min in the untrained control group. When the trained subjects refrained from physical training, the metabolic clearance rate decreased to 10.1 +/- 1.0 ml/kg/min at 60 h and further to 8.5 +/- 0.5 ml/kg/min after 7 days of detraining. The percentage of specific insulin binding to young erythrocytes (density 1.089-1.092), isolated by density gradient centrifugation, decreased from 10.4 +/- 0.9 at 12 h after the last exercise to 8.1 +/- 0.7%/3 X 10(9) cells after 60 h of detraining (P less than 0.001). The decrease in insulin binding to erythrocytes was almost entirely accounted for by a decrease in the number of insulin receptors. We conclude that the increase in peripheral insulin action seen in trained athletes is rapidly reversed, possibly by a mechanism separate from other phenomena associated with chronic training. The parallel findings of decreased in vivo insulin action and decreased insulin binding in young erythrocytes suggest that modulation of in vivo insulin response by detraining may be at least partially mediated by changes in insulin receptor number.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Ejaculatory incompetence: a theoretical formulation and case illustration.

Three theoretical formulations of ejaculatory incompetence have been proposed in the literature. They include: (1) aversive conditioned inhibition of the ejaculatory reflex, (2) an "autosexual" orientation associated with discrepant levels in the cognitive and physiological dimensions of sexual arousal, and (3) a discriminative learning model. These three models are discussed in relation to their theoretical and therapeutic implications. Clinical data supporting the discriminative view is presented.

Adult↗
PubMed1984

A comparison of three therapeutic formats in the treatment of secondary orgasmic dysfunction.

The goal of the present study was to compare the effectiveness of three therapeutic formats: Standard Couple Therapy, Group Therapy, and Minimal Contact Bibliotherapy (self-help) in the treatment of 23 couples in which the wife was suffering from secondary orgasmic dysfunction. The results indicate that a cognitive-behavioral sex therapy program is clearly effective in changing a wide range of subjective satisfaction and behavioral measures, with concurrence of the husbands' and wives' data providing further strength to these findings. Differences in outcome which were elicited in the three experimental treatment conditions were mainly in favor of the Standard Couple condition. Since such differences were neither frequent nor great, practical issues related to increasing the effectiveness of less time-consuming treatment formats are discussed. In addition, the theoretical implications of using global versus specific therapy outcome criteria are explored.

Adult↗
PubMed1984

Immune derangements in asymptomatic male homosexuals in Israel: a pre-AIDS condition?

We have described several immune derangements found in a clinically asymptomatic group of 117 male homosexuals (MHS) in Israel. These consisted of a marked decrease in TH and TS cells, decreased NK and allogeneic response, and increased levels of acid labile alpha-interferon and circulating immune complexes (CIC). Most of these alterations were found in approximately 40% of the subjects, with no simple correlation between them. Since Israel is a low incidence area for AIDS and related syndromes, it is suggested that this situation reflects a common situation among asymptomatic MHS in general, although the reasons for these impairments are not clear. This situation may therefore explain susceptibility of the male homosexual for developing AIDS, given the appropriate circumstances, environment, and genetic background.

Acquired Immunodeficiency Syndrome↗