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Biomedical subjects

M Berkowitz

Publications and source records attributed to M Berkowitz.

At least 19 recordsLinked to original sources
PubMed1999

Myocardial effects of ventricular fibrillation in the isolated rat heart.

OBJECTIVE: Ventricular fibrillation (VF) is known to increase myocardial oxygen requirements and to alter coronary vascular physiology. However, the significance of these effects during cardiac arrest and resuscitation is not well understood. A model was developed in the isolated rat heart to investigate the myocardial effects of VF during a simulated episode of cardiac arrest and resuscitation. We hypothesized that VF would intensify the severity of myocardial ischemia and consequently accentuate postischemic myocardial dysfunction. DESIGN: Prospective and randomized. SETTING: Research laboratory. SUBJECTS: Twenty Sprague-Dawley rats. INTERVENTIONS: Hearts were harvested and perfused at a constant flow rate of 10 mL/min using a modified Krebs-Henseleit solution equilibrated with 95% oxygen and 5% CO2. In five hearts, VF was induced by a 0.05-mA current delivered to the right ventricular endocardium. The perfusate flow was then stopped for a 10-min interval and resumed at 20% of baseline flow for another 10 mins. After 20 mins of VF, the perfusate flow was returned to baseline and a sinus rhythm reestablished by epicardial electrical shocks. The studies were randomized and included three additional groups to control for the effects of ischemia without VF (n = 5), the effects of VF without ischemia (n = 5), and the stability of the preparation (n = 5). MEASUREMENTS AND MAIN RESULTS: Isovolumic indices of left ventricular function were obtained using a latex balloon advanced through the mitral valve and distended to an end-diastolic pressure of 10 mm Hg. The coronary effluent was collected from the right ventricular cavity. VF during myocardial ischemia was associated with a higher coronary effluent PCO2, increased coronary vascular resistance, and development of ischemic contracture as indicated by increases in left ventricular pressure from 9+/-3 to 33+/-6 mm Hg (p < .05). After defibrillation, contractility and relaxation rapidly returned to baseline values, whereas the isovolumic end-diastolic pressure remained elevated for 20 mins. These changes were much less prominent when ischemia was not accompanied by VF. CONCLUSIONS: These findings indicate that VF may adversely affect myocardial ischemia by hastening the development of ischemic contracture, increasing coronary vascular resistance, and favoring the development of diastolic pump failure early after resuscitation from cardiac arrest.

Animals↗
PubMed1999

Androgen influence on lacrimal gland apoptosis, necrosis, and lymphocytic infiltration.

PURPOSE: Previous studies have shown that ovariectomy and hypophysectomy cause regression of the lacrimal gland and have implicated androgens as trophic hormones that support the gland. The purposes of this study were to test the hypothesis that glandular regression after ovariectomy is due to apoptosis, to identify the cell type or types that undergo apoptosis, to survey the time course of the apoptosis, and to determine whether ovariectomy-induced apoptosis could be prevented by dihydrotestosterone (DHT) treatment. METHODS: Groups of sexually mature female New Zealand White rabbits were ovariectomized and killed at various time periods up to 9 days. Additional groups of ovariectomized rabbits were treated with 4 mg/kg DHT per day. At each time period, sham-operated rabbits were used as controls. Lacrimal glands were removed and processed for analysis of apoptosis as assessed by DNA fragmentation and for morphologic examination. DNA fragmentation was determined using the TdT-dUTP terminal nick-end labeling assay and by agarose gel electrophoresis. Labeled nuclei were quantified by automated densitometry. Sections were also stained for RTLA (rabbit thymic lymphocyte antigen), rabbit CD18, and La antigen. Morphology was evaluated by both light and electron microscopy. RESULTS: The time course of apoptosis exhibited two phases, a rapid and transient phase and a second prolonged phase. A transient phase peaked at approximately 4 to 6 hours after ovariectomy. The values for degraded DNA as a percentage of total nuclear area were 4.29%+/-0.79% and 4.26%+/-0.54%, respectively. The values for sham-operated controls examined at the same time periods were 1.77%+/-0.08% and 0.82%+/-0.21%, respectively. The percentage of degraded DNA at 24 hours after ovariectomy was not different from controls examined at the same interval after sham operation. The percentage of degraded DNA 6 days after ovariectomy was significantly increased (8.5%+/-2.4%), compared with sham-operated animals at the same time period (0.68%+/-0.03%). DNA laddering was more pronounced after ovariectomy. Dihydrotestosterone treatment in ovariectomized rabbits suppressed the increase in DNA degradation. Morphologic examination of lacrimal gland sections indicated that ovariectomy caused apoptosis of interstitial cells rather than acinar or ductal epithelial cells. Tissue taken 4 hours and 6 days after ovariectomy showed nuclear chromatin condensation principally in plasma cells. Increased numbers of macrophages were also evident. Significant levels of cell degeneration and cell debris, characteristic of necrosis, were observed in acinar regions 6 days after ovariectomy. Dihydrotestosterone prevented this necrosis. Increased numbers of RTLA+, CD18+, and La+ interstitial cells were also evident 6 days after ovariectomy. In addition, ovariectomy increased La expression in ductal cells. Dihydrotestosterone treatment prevented the increase in numbers of lymphoid cells and La expression. Dihydrotestosterone also promoted the appearance of mitotic figures in acinar cells and increased the sizes of acini by 43% (P < 0.05). CONCLUSIONS: Glandular atrophy observed after ovariectomy is likely to proceed by necrosis of acinar cells rather than apoptosis. This process begins with an apparent time lag after a rapid phase of interstitial cell apoptosis. These processes are accompanied by increased lymphocytic infiltration. These results suggest that a critical level of androgen is necessary to maintain lacrimal gland structure and function and that a decrease in available androgen below this level could trigger lacrimal gland apoptosis and necrosis, and an autoimmune response. Because apoptotic and necrotic cell fragments may be sources of autoantigens that can be processed and presented to initiate an autoimmune reaction, we surmise that cell death triggered by androgen withdrawal may trigger an autoimmune response such as that encountered in Sjögren's syndrome. (ABSTRACT TRUNCATED)

Animals↗
PubMed1997

Complications of hydroxyapatite orbital implants. A review of 100 consecutive cases and a comparison of Dexon mesh (polyglycolic acid) with scleral wrapping.

PURPOSE: The authors analyzed all the complications associates with the first 100 hydroxyapatite orbital implants performed by one surgeon, and compare scleral wrapping versus Dexon mesh (polyglycolic acid, Davis & Geck, Manati, Puerto Rico) wrapping in light of these complications. BACKGROUND: Prior studies have not included the full range of complications that can occur with hydroxyapatite orbital implants. Dexon mesh implant wrapping is a promising substitute for sclera and avoids the risks involved in using donor tissue. METHODS: A retrospective analysis of 100 consecutive cases was performed. RESULTS: Many minor complications occurred, but the rate of exposure was low (3%) and no implant was lost. Dexon mesh wrapping was similar to scleral wrapping with respect to complications, although more posterior implant placement was necessary to avoid exposure in the Dexon-wrapped group. CONCLUSIONS: Surgeons and patients must be prepared for many minor complications when using hydroxyapatite orbital implants, but these can be readily overcome. Dexon mesh wrapping of the implant is recommended to avoid using donor tissue.

Adolescent↗
PubMed1995

[Corticosteroids in terminal cancer].

Corticosteroids are frequently prescribed in terminal cancer. They were prescribed in more than 50% of 100 consecutive patients of our hospice for palliation of anorexia, weakness, symptoms of cerebral metastases and of hypercalcemia, and other problems. There was objective and/or subjective improvement in most, though usually of short duration. If there is no improvement after a few days, corticosteroids should be discontinued.

Adrenal Cortex Hormones↗
PubMed1995

Survey of New Jersey schools and day care centers for lead in plumbing solder. Identification of lead solder and prevention of exposure to drinking water contaminated with lead from plumbing solder.

Levels of lead in drinking water can be high enough to pose a potential health threat to very young children, primarily from the use of lead solder for indoor plumbing. In February 1987, New Jersey banned lead solder for use in the installation or repair of drinking water plumbing systems. However, because lead solder continued to be available for purchase in the state, New Jersey Department of Health staff sought to (i) determine the extent to which schools and day care centers were in compliance with the ban, and (ii) determine the effectiveness of a solder analysis test kit commonly used by plumbing inspectors in the field. Samples of solder were collected from 53 day care centers and 37 schools known to have been constructed or renovated after the ban took effect. Samples from 24% of those facilities constructed or renovated just after the lead ban (1987-1988) tested positive for lead content. However, for those facilities constructed or renovated in later years (1989-1992), there was a decline in the percentage of samples that tested positive for lead content. For this period of time, 13% of the samples tested positive for lead. In total, more than 10% of facilities with new plumbing installed between 1987 and 1992 had solder samples that tested positive for lead. A lead in solder test kit commonly used by inspectors proved to be an effective screening tool for the field. The New Jersey Department of Health recommends continued enforcement of the lead solder ban through inspection and encouragement of behaviors that minimize consumption of potentially lead-contaminated drinking water. In order to assess patterns of water use, staff at the day care centers were asked to complete a questionnaire. Sixty-seven percent of the respondents reported that they "always" use water from the cold tap when preparing drinks or food for the children. In addition, 57% reported that they always first flush the tap before using the water for drinking or food purposes. Posters and pamphlets developed by the department and containing recommendations for how to minimize consumption of lead-contaminated drinking water were also provided.

Day Care, Medical↗
PubMed1995

Pulmonary function testing in spinal cord injury: correlation with vital capacity.

Spinal cord injury (SCI) causes restrictive ventilatory changes, with reductions in vital capacity, functional residual capacity, and expiratory reserve volume. Vital capacity (VC) often is used as an indicator of overall pulmonary function in these patients. In an effort to determine the extent to which VC correlates with other pulmonary function tests, 52 patients with recent acute traumatic SCI underwent complete pulmonary function testing. Statistical relationships were determined between VC and nine other tests. VC was found to be significantly correlated with forced expiratory volume in 1 s, inspiratory capacity, expiratory reserve volume, functional residual capacity, residual volume (RV), total lung capacity (TLC), and RV/TLC ratio, but not with maximum positive expiratory pressure nor with maximum negative inspiratory pressure. The excellent correlations between vital capacity and nearly all of the other pulmonary function tests support the use of VC as a single global measure of overall ventilatory status in SCI patients.

Adolescent↗
PubMed1995

Preferred usage of specific immunoglobulin gene segments in chronic lymphocytic leukaemia cells of three HLA-identical sisters.

We report three family members, including a set of identical twins, who developed CD5 positive B-CLL. The patients are female Ashkenazi Jews sharing an identical HLA phenotype. Two of the HLA loci (B35 and Cw4) were common with those already described as being shared by Ashkenazi Jews with an increased incidence of CLL. The rearranged immunoglobulin genes of the malignant cells of all three patients were found to express genetically related VH regions belonging to the VH3 subgroup, and chromosomal studies suggest a process of clonal evolution in one of the twins.

Aged↗
PubMed1994

Prevention of thromboembolism in spinal cord injury: role of low molecular weight heparin.

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major causes of morbidity and mortality in patients with acute spinal cord injury. Our preliminary studies indicated that low molecular weight heparin (LMWH) was significantly more effective than standard heparin in preventing these complications. We have now extended these studies by screening an additional 122 patients and treating 60 who met predefined criteria with LMWH in a dose of 3,500 anti-Xa U given subcutaneously once daily for 8 weeks. All patients were examined daily at bedside and had regularly scheduled venous ultrasonography; those with abnormalities had confirmatory venography and lung scans. Postmortem examinations were conducted in those who died. Forty completed the trial without incident, 6 had DVT (4 proximal and 2 distal), 1 had a fatal PE, 1 had postoperative bleeding requiring discontinuation of the LMWH, 10 were transferred or discharged, and 2 died of respiratory failure. The percentage of patients free of thrombosis or bleeding after 8 weeks of treatment was 85.9 +/- 5.0% standard error of mean (SEM). Thirty-three patients entered a follow-up observation period of 4 weeks without thromboprophylaxis; 2 weeks into this period 1 had a proximal DVT and 1 had a fatal PE; the course of the remainder was uneventful. We conclude that LMWH compares favorably with standard heparin in preventing venous thromboembolism, and is associated with significantly less bleeding. Eight weeks of prophylaxis seems adequate for most patients.

Adult↗
PubMed1994

Drinking Water Contamination and the Incidence of Leukemia and Non-Hodgkin's Lymphoma.

>A study of drinking water contamination and leukemia and non-Hodgkin's lymphoma (NHL) incidence (1979-1987) was conducted in a 75-town study area. Comparing incidence in towns in the highest trichloroethylene (TCE) stratum (>5 microg/l) to towns without detectable TCE yielded an age-adjusted rate ratio (RR) for total leukemia among females of 1.43 (95% CI 1.07-1.90). For females under 20 years old, the RR for acute lymphocytic leukemia was 3.26 (95% CI 1.27-8.15). Elevated RRs were observed for chronic myelogenous leukemia among females and for chronic lymphocytic leukemia among males and females. NHL incidence among women was also associated with the highest TCE stratum (RR = 1.36; 95% CI 1.08-1.70). For diffuse large cell NHL and non-Burkitt's high-grade NHL among females, the RRs were 1.66 (95% CI 1.07-2.59) and 3.17 (95% CI 1.23-8.18), respectively, and 1.59 (95% CI 1.04-2.43) and 1.92 (95% CI 0.54-6.81), respectively, among males. Perchloroethylene (PCE) was associated with incidence of non-Burkitt's high-grade NHL among females, but collinearity with TCE made it difficult to assess relative influences. The results suggest a link between TCE/PCE and leukemia/ NHL incidence. However, the conclusions are limited by potential misclassification of exposure due to lack of individual information on long-term residence, water consumption, and inhalation of volatilized compounds.

Journal Article↗
PubMed1993

Assessing the socioeconomic impact of improved treatment of head and spinal cord injuries.

Assessment of improved treatment of neurotrauma presents two basic challenges: 1) measurement of the medical effects of treatment, and 2) evaluation of these effects in socioeconomic terms. A nationwide survey was conducted in 1988 to estimate the prevalence of persons in the United States who suffered traumatic spinal cord injury and to calculate its economic consequences. Seven hundred fifty-eight persons weighted to be representative of the spinal cord injury population were interviewed. The prevalence rate was found to be 721 cases per million people. Conservative calculations for 1988 showed that the average direct costs per person were $103,000 for hospitalization and home modifications during the first 2 years postinjury and $14,000 per year thereafter for medical care. Losses in earnings and homemaker services averaged $12,726 per year. Total aggregate costs for 1 year were estimated at $5.6 billion. Lifetime costs for a representative person with complete paraplegia injured at age 33 were estimated to be $500,000. For a representative person with complete quadriplegia injured at age 27, these costs amounted to $1 million. These data can be used to estimate cost savings related to decreased disability resulting from improved treatment.

Adult↗
PubMed1992

New estimates of the direct costs of traumatic spinal cord injuries: results of a nationwide survey.

New estimates of the direct costs of traumatic spinal cord injuries (SCI) are obtained from a comprehensive survey of the US SCI population. These direct costs, defined as the value (in 1988 dollars) of resources used specifically to treat or to adapt to the SCI condition, represent the average experience of the US SCI population. Responses to a detailed questionnaire administered to a sample of traumatic SCI persons in the United States provide the primary source of data for this study. Analysis of this survey data indicates that more recently injured SCI persons (ie those injured since 1970) spent an average of 171 days in a hospital over the first 2 years post injury. Initial hospital expenses will average $95,203. Home modification costs in excess of $8,000 can also be expected. After recovery and rehabilitation, a SCI person will pay, on average, $2,958 per year in hospital expenses and $4,908 per year for other medical services, supplies and adaptive equipment. Personal assistance costs and costs of institutional care will average $6,269 per year. These cost estimates represent the incremental costs of SCI, ie they exclude any costs that would have been incurred in the absence of SCI.

Adolescent↗
PubMed1989

Hydration forces between parallel DNA double helices: computer simulations.

We have performed two molecular dynamics computer simulations of two 10-base-pair segments of DNA molecules immersed in water. The goal of these simulations is to study the structural and dynamical properties of water between the DNA molecules. We have observed water ordering next to DNA surfaces. Existence of such ordering was proposed earlier by Marcelja and Radic [Marcelja, S. & Radic, N. (1976) Chem. Phys. Lett. 42, 129-130] to explain strong hydration forces between macromolecular surfaces.

Chemical Phenomena↗
PubMed1984

Dendritic cell identification in head and neck lymphoid tissue. Newly recognized cells control T-lymphocyte functions.

The physiologic measurements of a subpopulation of mononuclear cells derived from head and neck lymphoid tissues are similar to those of dendritic cells are described. Dendritic cells are a subpopulation of bone marrow-derived leukocytes that were originally identified in rodents and now described in man as having central control of T-lymphocyte functions. We describe a technique for the enrichment of dendritic cells obtained from tonsils utilizing a bovine serum albumin (BSA) gradient and note that they have the light and electron microscopic appearance of dendritic cells. The measured oxidative mitogenic response and interferon-gamma production in complete leukocyte cultures was compared with BSA gradient-separated preparations. The denser cells, comprised mostly of normal appearing lymphocytes, would not undergo a mitogenic response nor produce normal amounts of interferon when stimulated unless the dendritic cell-rich, less-dense fraction, was added back. The dendritic cells derived from tonsils seem to behave as a potent accessory cell for these T-lymphocyte-associated functions.

Animals↗
PubMed1984

Transcription of ground-state density-functional theory into a local thermodynamics.

The concepts of local temperature, local entropy, and local free energy density are introduced within the framework of the ground-state density-functional theory of many-electron systems, and a complete local thermodynamic picture is then developed. A view emerges of the electron cloud, as analogous to a classical inhomogeneous fluid moving under gradients of temperature, pressure, and an effective potential, described by a locally Maxwellian distribution.

Kinetics↗
PubMed1983

The optimal stock of health with endogenous wages. Application to partial disability compensation.

The optimal quantity of health is examined in the framework of a model which posits that health capital will influence earning capacity in addition to the supply of labor. Utilizing data from the Survey of Disabled and Nondisabled Adults, eight health capital variables are tested in models of hourly wages, labor supply and yearly earnings. The results for three of the health capital variables are then compared to their evaluation by the American Medical Association and by the New York State Workers' Compensation program.

Absenteeism↗