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Biomedical subjects

A Cohen

Publications and source records attributed to A Cohen.

At least 487 records · Page 27Linked to original sources
PubMed1992

Successful dissolution of massive left atrial thrombus after the use of warfarin--a case report.

A case of rheumatic heart disease, mitral stenosis, large left atrium, and chronic atrial fibrillation is reported and discussed. This patient was shown, by means of two-dimensional echocardiography, to have a massive left atrial thrombus, and after the initiation of anticoagulation with warfarin, complete resolution of the clot was seen in less than two months. The use of two-dimensional echocardiography was valuable in the follow-up of this patient, and it is suggested that further prospective studies are necessary for better understanding the natural history of left atrial thrombus.

Aged↗
PubMed1992

Correlation between destruction of malarial parasites by polymorphonuclear leucocytes and oxidative stress.

The role of reactive oxygen species (ROS) generated by polymorphonuclear leucocytes (PMNs) in the host response against malaria was investigated. Non-activated human PMNs were added to cultures of P. falciparum in microtitre cells. Parasite viability was evaluated by the incorporation of radioactive hypoxanthine. Using PMN/RBC = 1/150 (starting parasitemia was 1%) the incorporation on the second day in culture was only 61% of the control cultures. An effect could be observed already after two hours of incubation (30% reduction at a 1/50 PMN/RBC ratio). A direct contact between the effector and target cells was obligatory for the expression of the damage. Parasites within G6PD-deficient erythrocytes were more sensitive to the PMNs than normal parasitized erythrocytes. This difference could be attributed to the production of reactive oxygen intermediates in the experimental system, since G6PD-deficient erythrocytes are generally more sensitive to oxidant stress. Salicylic acid was used as a scavenger and reporter molecule for hydroxyl radical fluxes. It is converted to the corresponding dihydroxybenzoic acid derivatives, which could be detected by HPLC. Uninfected NRBC or parasitized erythrocytes containing young ring forms could trigger the PMNs to produce much less ROS than the mature forms of the parasites. Other factors associated with PMNs may inactivate the parasites, such as phagocytosis, lysosomal enzymes or degradation toxic products of the PMNs. However our results indicate that increased oxidative stress induced by PMNs interfere with the growth of P. falciparum and could play a role in human evolution of abnormal erythrocytes.

Animals↗
PubMed1992

[Early constrictive pericarditis after coronary revascularization. Apropos of a case].

The authors report a case of severe constrictive pericarditis occurring 6 weeks after coronary bypass surgery and in the absence of any other predisposing factor. The diagnosis was confirmed by CT scan and cardiac catheterisation which showed signs of a diastole. The patient died despite early surgical reoperation because of the severity of the pericardial fibrosis.

Aged↗
PubMed1992

Expression of cytokines and their receptors by human thymocytes and thymic stromal cells.

The repertoire of cytokine and cytokine receptor mRNA expressed by unstimulated human thymocytes and thymic stromal cells was explored by a quantitative polymerase chain reaction (PCR) using sequence specific internal standards. Of the 18 cytokines tested we found a considerable overlap in the expression of cytokines by human thymocytes and by thymic stromal cells; both cell types express the mRNA for interleukin-1 beta(IL-1, IL-6, IL-7 and tumour necrosis factor-alpha (TNF-alpha). However, there are substantial differences in the levels of cytokine mRNA expressed in these two types of cells as revealed by the quantitative PCR assay. Stromal cells express considerably higher levels of IL-1 beta and IL-6 than thymocytes (14- and 27-fold respectively). In addition, a number of cytokines such as lymphotoxin and interferon-gamma (IFN-gamma), are expressed exclusively in thymocytes whereas others such as stem cell factor (SCF), IL-1 receptor antagonist-2 (IRAP-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are produced only in stromal cells. There is a complete overlap in the expression of a group of cytokine receptors tested in thymocytes and thymic stromal cells; these include IL-1R, IL-2R, IL-6R, IL-7R, TNFR and stem cell growth factor receptor (c-KIT). The expression of specific cytokines by thymic stromal cells and the parallel expression of their receptors on thymocytes under physiological conditions, support the hypothesis that these cytokines participate in paracrine interactions between these two cell populations during thymocyte differentiation.

Cells, Cultured↗
PubMed1992

Conservative surgery and radiation therapy for intraductal carcinoma of the breast.

Nineteen women with intraductal carcinoma of the breast were treated with conservative surgery and radiotherapy from 1982 to 1990. All underwent excisional biopsy or wide local excision of the primary tumor. Definitive irradiation consisted of 4500 cGy in 180 cGy fractions given through tangential fields followed by a breast boost to the primary site to a total dose of 5900-6500 cGy. No patient received regional node irradiation. Median follow-up was 38 months. The five year actuarial rate of local failure was 9%. One patient failed with an infiltrating ductal carcinoma in the treated breast 31 months after initial treatment. Salvage mastectomy was performed. She remains without evidence of disease 43 months after initial treatment. Metastatic breast carcinoma has not developed in any of the patients. Cosmetic result was good to excellent in all patients. With short-term follow-up, conservative surgery and radiotherapy appear to be an acceptable alternative to mastectomy in carefully selected patients with ductal carcinoma in situ. As retrospective and randomized trials mature, the natural history of these lesions treated with conservative surgery and irradiation will be further defined.

Adult↗
PubMed1992

The current value of exercise testing soon after acute myocardial infarction.

We performed exercise testing in 236 of 289 survivors of acute myocardial infarction to test the hypothesis that exercise-related parameters contribute to cardiac prognosis. Beta-blockers and/or calcium antagonists were used by 50% and 55% respectively of the study population. Of the 236 patients 67 had received thrombolytic therapy during the acute event. By either univariate or multivariate analysis, we found that exercise-related parameters were poor predictors of cardiac prognosis. Therefore, in our population, exercise testing performed 3 weeks after myocardial infarction provides little information of prognostic value.

Academic Medical Centers↗
PubMed1992

[Does ambulatory determination of blood pressure allow the measurement of white coat effect?].

UNLABELLED: The aim was to find an objective indicator in order to evaluate white coat effect (WE). The first hour average values after placing an ambulatory blood pressure recorder (15 mn intervals) were compared to those of the 4 following hours of diurnal activity. A first hour systolic arterial blood pressure (SBP 1H) increase of 10 mmHg or more was considered as an ambulatory WE positive (AWE+) and was compared to clinical WE (CWE). CWE+ was observed in 78 pts and AWE+ in 72 among a group of 172 unselected pts referred for hypertension. RESULTS: the correlation between AWE and CWE is weak (r = 0.49) but significant (p < 0.001). There was no difference between the two groups in age, sex, clinical blood pressure, heart rate or ambulatory BP after the first hour (table). There was a significant difference in SBP between the 2 groups (p < 0.001) during the first hour only. [table: see text] CONCLUSION: Ambulatory blood pressure recording is able to recognize and evaluate the white coat effect. We suggest to consider independently the first hour of each recording and to compare it with the mean pressure measured during the period of diurnal activity.

Adult↗
PubMed1992

Association of intrauterine cigarette smoke exposure with indices of fetal lung maturation.

The timing of fetal lung maturation is regulated, at least in part, by the fetal endocrine milieu, which in turn may be influenced by environmental factors. Infants of smoking mothers are at decreased risk of neonatal respiratory distress syndrome (RDS), a disease of lung immaturity. Therefore, we measured fetal lung maturity and cigarette smoke exposure to determine whether the lungs of smoke-exposed fetuses mature more quickly and whether changes in maturation are associated with alterations in amniotic fluid (AF) cortisol levels. Amniotic fluid lecithin-sphingomyelin ratio (L/S) and saturated phosphatidylcholine levels were used as measures of lung maturity, while smoke exposure was assessed by measuring AF cotinine, a stable nicotine metabolite. Lung maturity was more advanced in smoke-exposed fetuses as measured by saturated phosphatidylcholine (P = .02) and L/S ratio (P = .04). Smoke-exposed fetuses attained sufficient lung maturity to minimize the risk of RDS approximately 1 week earlier than in unexposed fetuses. The AF of smoke-exposed fetuses also had higher levels of free, conjugated, and total cortisol. Acceleration of lung maturation in smoke-exposed fetuses is consistent with the decreased risk of RDS in infants of smoking mothers. Maternal smoking could influence lung maturation by directly or indirectly enhancing the production and/or secretion of cortisol. Despite the decreased risk of RDS, the developmental process by which smoke-exposed fetuses attain early pulmonary maturity is abnormal and may contribute to the decreased lung function and increased respiratory illness noted in infants of smoking mothers.

Adult↗
PubMed1992

Neonatal behavior of Panamanian and Israeli infants: a cross-cultural study.

The behavior of third-generation Israeli neonates belonging to two ethnic groups--Ashkenazic infants (n = 20) and Sephardic infants (n = 20)--and the behavior of a group of full-term Panamanian infants (n = 30) were compared in order to examine cross-cultural and interethnic predispositions. The Israeli and Panamanian infants differed on 5 of a total of 27 neonatal behavioral assessment items: the difference in 3 of these items, representing the autonomic stability and motor clusters, exceeded 1 scale score. A comparison of the two Israeli ethnic subgroups with the Panamanian group (Duncan's multiple-range test) revealed significant differences between Ashkenazic and Sephardic infants on 2 auditory habituation items, whereas the Panamanian infants differed significantly from both Israeli subgroups on 10 of the items, representing the motor, range of state, and autonomic stability clusters. These results corroborate previous observations concerning cross-cultural neonatal behavioral differences and the possible role of environmental factors in the ongoing modeling process of human behavioral traits and personality.

Child Behavior↗
PubMed1992

The effects of ascorbate-induced free radicals on Plasmodium falciparum.

Ascorbic acid has been shown to cause stage-dependent effects on the in vitro development of Plasmodium falciparum. While vitamin C marginally enhanced the development of young parasites, it proved highly destructive to the advanced forms. The present study evaluates the mechanisms by which vitamin C affects the parasite. The treatment of parasitized erythrocytes with ascorbate resulted in the conversion of added salicylate to dihydroxybenzoate products, indicating the involvement of hydroxyl radicals. There was a stage specific sensitivity, increasing conversion with progressing parasite development. This specificity could not be attributed to the altered uptake of salicylate by the parasitized erythrocyte, since salicylate uptake was similar in either parasitized or non-parasitized erythrocytes. In distinction, increased uptake of ascorbate by parasitized erythrocytes could account for an elevated oxidant stress. The treatment with ascorbate also caused the oxidation of hemoglobin to methemoglobin and the peroxidation of membrane lipids. Added catalase markedly inhibited the ascorbate-induced effects on parasite development. "Free" plasmodia were also vulnerable to treatment with ascorbate like the parasites within their host cells. These results are in accord with a free radical mechanism of damage to the infected erythrocytes. During the growth of P. falciparum the infected erythrocytes release increasing levels of iron-containing structures that are redox-active and can catalyze the formation of highly reactive oxygen derived species. The findings also indicate the multiplicity of the mode of action of ascorbate on the host-parasite system.

Animals↗
PubMed1992

Buprenorphine: an alternative to methadone for heroin dependence treatment.

Eighty-five heroin addicts who were unwilling to receive methadone maintenance or enter therapeutic communities were assessed, single-blind, for the lowest sublingual dose of buprenorphine that blocked heroin craving (8.0 mg max). All doses were administered daily under observation. After maintenance for 4 to 12 weeks, abstinent subjects (confirmed by urine drug screens) entered a double-blind discontinuation trial and were randomly assigned to receive dose reductions (10% twice weekly for 5 weeks to zero dose, then placebo for 2 weeks) or a stable dose for 7 weeks. Subjects were terminated from discontinuation if heroin was used or they had increased craving/symptoms. Subjects completed the trial if they did not use heroin and had no increase in craving/symptoms. A wide dose range (1.5-8.0 mg/day) was effective in reducing heroin craving and use. Of 73 subjects who received buprenorphine for 4 to 52 weeks, 40 had no prior treatment, despite high levels (mean $/day heroin = 70.5 +/- 94.7) and many years (mean years = 10.7 +/- 8.6) of dependence. Subjects who received dose reductions developed abstinence symptoms, low energy most commonly, associated with drug-seeking behavior. Discontinuation trial outcome (n = 51) shows a highly significant difference between 29 subjects who received dose reductions (28 terminated, 1 completed) and 22 subjects who received no dose reductions (3 terminated; 19 completed) (chi-square = 36.08; p less than .00001). The findings suggest that buprenorphine could be an important medication for reducing demand for heroin by many heroin addicts who remain outside the present health-care system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Constitutive expression and role in growth regulation of interleukin-1 and multiple cytokine receptors in a biphenotypic leukemic cell line.

A cell line (B1) was established from the bone marrow of a patient with a relapse of acute leukemia characterized by a 4;11 chromosomal translocation and biphenotypic features of early B and myeloid lineages. Analysis of the growth requirements of this cell line showed density-dependent growth and secretion of an autostimulatory growth factor, suggesting an autocrine mechanism. Several lines of evidence implicate the participation of interleukin-1 (IL-1) in the autocrine growth regulation of B1 cells. These cells constitutively express the messenger RNA (mRNA) for IL-1 and IL-1 receptor and secrete IL-1; recombinant IL-1 stimulated the growth of colonies when cells were seeded at low density, and anti-IL-1 antibodies inhibited the growth of colonies with cells seeded at higher density. B1 cells do not express detectable levels of mRNA for any of the other cytokines tested, and other cytokines failed to support the growth of B1 cells at low density. In addition, B1 cells express multiple cytokine receptor genes, including the receptors for IL-6, IL-7, tumor necrosis factor and gamma-interferon. Addition of the respective cytokines to the B1 cells resulted in inhibition of the growth of leukemic cells in vitro. The multiplicity of growth-inhibitory cytokine receptors on this leukemic cell line might be due to its biphenotypic lineage and may suggest new therapeutic possibilities in controlling leukemic cell proliferation.

Acute Disease↗
PubMed1991

[Air pollution and morbidity in the Haifa region].

The effects of exposure to air pollution (defined by levels of SO2) were studied in a representative sample of over 3,500 households in the greater Haifa area. The sample was drawn from 16 high and low pollution neighborhoods which also represented different socioeconomic strata. A very significant relationship was found between levels of pollution in residential and work areas and self-reported respiratory symptoms and diseases. This finding was strongly supported by a statistically significant relationship between actual measured levels of pollution in the 2 weeks prior to the interview and the use of medical services by both adults and children, as well as by the number of days their activity was restricted during that period.

Adult↗
PubMed1991

Tumor necrosis factor facilitates regeneration of injured central nervous system axons.

The results of this study attribute to tumor necrosis factor (TNF) a role in regeneration of injured mammalian central nervous system (CNS) axons which grow into their own degenerating environment. This is the first time that a specific factor involved in axonal regeneration has been identified. The axonal environment is occupied mostly by glia cells, i.e., astrocytes and oligodendrocytes. Previous studies have shown that mature oligodendrocytes are inhibitory to axonal growth. Therefore, it seemed likely that application of a factor such as TNF, which has been shown to be cytotoxic to oligodendrocytes, would contribute to the creation of permissive conditions for axonal regeneration. In the present work, injured adult rabbit optic nerves were treated with human recombinant TNF (rhTNF). As a result, abundant newly growing axons (circa 9000, about 4% of the total estimated number of axons in an intact adult rabbit) were observed traversing the site of injury.

Animals↗
PubMed1991

ATP-induced activation of human B lymphocytes via P2-purinoceptors.

ATP-specific P2-purinoceptors expressed on various cell types have been shown to trigger cell activation via a phospholipase C pathway. In the present study, we provide evidence that P2-purinoceptors are expressed on B lymphocytes but not on T lymphocytes. ATP at concentrations of 10 to 100 microM triggered a dose-dependent increase in inositol 1,4,5-trisphosphate (IP3) levels as well as total inositol phosphate in human B lymphocytes. As expected from the changes in IP3, incubation of B cells with increasing concentrations of ATP lead to a dose-dependent increase in cytosolic free Ca+2 ([Ca+2]i). Extracellular ATP also induced increases in the levels of c-fos and c-myc mRNA. Because no responses were elicited by other nucleotides, the increase in IP3 production, the rise in [Ca+2]i levels, and the enhanced expression of c-fos and c-myc mRNA seem to be mediated by P2-purinoceptors. These responses were exclusive to B lymphocytes, in that ATP had no effect on IP3, [Ca+2]i, or oncogene expression in T cells. The results show that binding of extracellular ATP to P2-purinoceptors on quiescent B cells leads to the activation of genes associated with cell activation. This appears to be mediated via the phospholipase C signal transduction pathway.

Adenosine Triphosphatases↗