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Biomedical subjects

Y Cohen

Publications and source records attributed to Y Cohen.

At least 127 records · Page 7Linked to original sources
PubMed1997

Endometrial carcinoma in the south of Israel: study of 231 cases.

BACKGROUND AND OBJECTIVES: Endometrial carcinoma is the commonest female genital tract malignancy in the south of Israel. The purpose of this study was to investigate the clinical and histologic findings, treatment and outcome of patients with endometrial carcinoma in the south of Israel. METHODS: Data from the files of 231 patients with endometrial carcinoma who were managed at the Soroka Medical Center between January 1961 and December 1994 were evaluated. RESULTS: Endometrial carcinoma was more prevalent among Jewish as compared to Arab-Beduin women, and among Ashkenazi as compared to Sephardic Jewish women. The prevailing presenting symptom was postmenopausal bleeding and most patients (68.8%) had Stage I disease. Most patients (209/225, 92.9%) underwent surgery, 131/222 (59%) had radiotherapy and 15/214 (7%) received chemotherapy. The 5-year survival rate was 79.1% overall; 89% for Stage I, 71.7% for Stage II, 21.6% for Stage III and 0% for Stage IV; 89.8% for Grade 1, 70% for Grade 2 and 60.9% for Grade 3; 100% for adenoacanthoma, 82% for endometrioid carcinoma, 65.8% for adenosquamous carcinoma and 51.6% for papillary serous carcinoma. CONCLUSIONS: Endometrial carcinomas are characterized by a relatively favorable prognosis with a 5-year survival of about 80%. Surgical stage, histologic differentiation and histologic subtype are sensitive predictors of survival. The mainstay of treatment is surgery with adjuvant pelvic radiotherapy when necessary.

Adult↗
PubMed1997

In vivo observation of anisotropic motion of brain water using 2H double quantum filtered NMR spectroscopy.

The 2H DQF NMR spectra of deuterated water molecules were measured for the first time in in vivo rat brain. The observation of the DQF signal indicates that there is a water population that exhibits anisotropic motion. The characteristics of the DQF spectra premortem and postmortem are very similar (lineshape and relaxation times). In the 1st h there is a 10-15% decrease in the signal intensity of the DQF spectra followed by a gradual but a much slower decrease in the DQF signal intensity that reaches 65-70% of its initial value after only 12 h. When the brains were kept at 4 degrees C, a 40% decrease in the DQ signal intensity was observed only after 7 days. Mechanical chopping of the brain tissues causes an immediate loss of more that 97% of the DQ signals. The slow, temperature-sensitive decay of the signal, and its sensitivity to mechanical treatment point out that these signals originate from water molecules that interact with structural components in the brain. The characteristics of the DQF spectra depend on the amount of bulk water as exemplified by increased residual quadrupolar interaction and relaxation rates obtained when dehydrating the brain tissue.

Animals↗
PubMed1997

The effect of air pollution on the integrity of chlorophyll, spectral reflectance response, and on concentrations of nickel, vanadium, and sulfur in the lichen Ramalina duriaei (De Not.) Bagl.

The following study was designed to determine the environmental impact of pollutants emitted by combustion of heavy fuel oil in Ashdod, in Southwestern Israel. For this purpose we measured concentrations of total S, V, and Ni in the local epiphytic fruticose lichen Ramalina duriaei, which grows in the peripheral region of the town, and compared these results with those obtained in thalli collected 100 km away, in the HaZorea Forest, northeastern Israel. We also transplanted thalli from the HaZorea Forest to the Ashdod region for a 10-month period. At the end of the experiment we measured the elemental content in all samples. In addition we measured chlorophyll degradation expressed as changes in the 435 nm/415 nm OD ratio, and changes in the spectral responses of the thalli. In several sites in the Ashdod region we found high concentrations of S, V, and Ni in transplanted thalli, which correlated with the NDVI values. These findings agree with other measurements of SO2 and V in the Ashdod area. We suggest that a high V/Ni ratio in lichens is a tracer for air pollution caused by the combustion of heavy fuel oil.

Air Pollutants↗
PubMed1997

Herbivores, the Functional Diversity of Plants Species, and the Cycling of Nutrients in Ecosystems

Numerous investigators have suggested that herbivores almost always increase rates of nutrient and energy flow through terrestrial ecosystems by returning to the soil fecal material and urine with faster turnover rate than shed plant litter. These previous theories and models always treat the producer compartment as a homogenous pool. Essentially, they assume that consumers feed through a pureed cream of vegetable soup. However, many field observations and experiments have shown that consumers feed selectively (i.e., in a cafeteria) and that consumer choice is made on the same chemical basis that determines decomposition rates. Plants that are preferred food sources often have higher nutrient content, higher growth rates, and faster decomposition rates. As consumption reduces dominance of these species in favor of unpreferred species with slower decomposition, rates of nutrient cycling and energy flow should therefore decline. We analyze a model in which the consumer is given a choice among producers that vary in nutrient uptake rates, rates of nutrient return to decomposers, and consumer preference, and which is parameterized for plants and consumers characteristic of boreal regions. In this model, in an open, well-mixed system with one consumer and two such producers, the nutrient/energy flow will not exceed that of a system without the consumer. If the consumer has a choice between two such producers, it must choose one plant over the other at a greater ratio than that between the two plants in uptake and decay rates. In contrast, in a closed system the consumer must be less selective to coexist with the two plants. The system behavior is determined by the level of nutrient return through the consumer and the differences between the plants in nutrient uptake rates and consumer preference. Species richness affects properties of this model system to the extent that species are functionally distinct (i.e., have different rate constants) in a multivariate space of life history traits (i.e., nutrient uptake and palatability). We suggest that the biochemical variability of plant tissues that simultaneously determines both consumer preference and decomposition rates is an essential feature of food webs that cannot be ignored. Thus, ecosystem models should, at minimum, consider more than one producer type with consumer preference.

Journal Article↗
PubMed1997

5-Hydroxytryptamine and beta-adrenoceptors in rat isolated atria.

The positive chronotropic effect of a high concentration of 5-hydroxytryptamine (5-HT) in rat isolated atria results mainly from a tyramine-like mechanism and is linked to an increase in cAMP production by an indirect stimulation of beta-adrenoceptors. Using this preparation, we have compared the action of tyramine and 5-HT. The tyramine (0.15 microM)-induced increase in atrial rate was suppressed by atenolol (a beta 1-blocking drug) and by nadolol (a beta 1 beta 2-blocker), while the positive chronotropic effect of 5-HT was reduced by atenolol and suppressed by nadolol. The 5-HT-induced elevation in cAMP was unchanged in the presence of atenolol and abolished by nadolol. The involvement of beta 2-adrenoceptors in the effects of 5-HT could result from competition between 5-HT and noradrenaline at the beta 1-adrenoceptors that results in a fixation of noradrenaline on beta 2-adrenoceptors.

Adrenergic Agents↗
PubMed1997

Cardiovascular pharmacology of aqueous extract of the leaves of Bridelia atroviridis Muell. Arg. (Euphorbiaceae) in the rat.

Lyophilised decoction (10%) of the leaves of Bridelia atroviridis Muell. Arg. (Euphorbiaceae) was studied in the rat cardiovascular system. In vivo, the extract (15 and 30 mg/kg) caused a decrease of arterial pressure and a decrease of heart rate in an anaesthetized rat (ethylcarbamate 1.2 g/kg). If administrations of Bridelia were repeated (three times) a tachyphylaxie phenomena was observed. After administrations of adrenaline, noradrenaline, acethylcholine and isoprenaline the extract had no effect on the action of these neuromediators on blood pressure. In vitro the extract induced dose-dependent negative inotropic and chronotropic effects in isolated rat heart. It was ineffective in rat aorta preparations. Bridelia seemed to have a direct effect on rat heart. Hypotension is not due to an action on the vessels. The extract did not appear to interact with adrenergic nor cholinergic receptors. However, the extract was able to potentiate barium chloride induced contractions of rat aorta preparations. The extract might act through potential dependent calcium channels.

Animals↗
PubMed1997

Diffusion- and T2-weighted MRI of closed-head injury in rats: a time course study and correlation with histology.

Diffusion- and T2-weighted MRI were used to evaluate changes in brain water characteristics following closed-head injury in rats. Images were collected within the first 2 h and at 24 h and 7 days following the traumatic event and then compared with histology. The ratios between the apparent diffusion coefficients (ADCs) of the traumatized tissues and normal brain tissues were significantly different from unity and were found to be 0.79 +/- 0.25 (p < 0.01), 0.49 +/- 0.33 (p < 0.0002), and 3.47 +/- 1.36 (p < 10(-6)) at 1-2 h, 24 h, and 1 week after the trauma, respectively. In severe trauma, areas of hyperintensity which were not apparent on the T2-weighted images could be detected on the diffusion-weighted images within 1-2 h after the trauma. At 24 h following the traumatic event, large areas of hyperintensity are observed in both types of images. One week following the trauma, the ADCs of the traumatized tissues (1.84 +/- 0.69 x 10(-5) cm2/s) are much larger than those of normal brain (0.57 +/- 0.19 x 10(-5) cm2/s) and approach the value of free water. At 7 days, the areas of hyperintensity in the T2-weighted images seem to underestimate the injured areas found by histology. At this time point a good correlation is obtained between the areas of hypointensity observed on the diffusion-weighted images and the infarct areas obtained by histology (r = 0.88).

Animals↗
PubMed1997

A cross-cultural comparison of behavior disturbance and suicidal behavior among psychiatrically hospitalized adolescents in Israel and the United States.

American adolescent psychiatric patients had significantly higher levels of suicidal behavior (49% vs. 19%) and a higher percentage of depression diagnoses (78% vs. 24%) than Israeli psychiatric inpatients. After controlling for the diagnosis of depression, American male patients obtained significantly higher scores on the Obsessive-Compulsive, Aggression, and Hyperactive subscales of the Child Behavior Checklist (CBCL) than the Israeli males. American females scored higher on the Depression subscale than Israeli females. Differences may be attributed to less tolerance or differing perceptions of deviant behavior in America, clinical practice, and/or the CBCL's greater applicability to American inpatient samples.

Adolescent↗
PubMed1997

Attachment as the basis of psychopathological development and residential treatment.

There seems to be an as yet unresolved question as to whether attachment behavior is an innate factor or whether it is an outcome of primary social relations. On the basis of Bowlby's researches as well as on Emde's, the author argues that attachment is an innate developmental factor that needs external impact, meaning parental care, to evolve and develop. The two cases presented here reflect similar expressions of alienation and detachment as well as essential differences. In the first case, the child has lost his innate ability and urge for social attachment due to severely defective care during early infancy, mainly desertion. In the second case, the child expresses clear attachment ability, yet, due to the deviant care, this ability has developed into disturbed attachment patterns. In both cases, it is claimed that only comprehensive treatment, which is in a way removed from reality, may "rekindle" the innate attachment ability of the first child and lead the second child to unimpaired attachment behavior.

Child↗
PubMed1997

Where is the "inverting factor" in hormone secretion from parathyroid cells?

Secretion of hormones and transmitters in the body fall into two general categories. In the majority of the secreting cells, including the presynaptic terminals in the nervous system, an increase in the extracellular calcium causes an increase in secretion. There are two notable exceptions to this general rule: the parathyroid cells and the renal juxtaglomerular cells, where an increase in extracellular calcium leads to a decrease in secretion. Because these two cell types have a cardinal role in a wide variety of physiological and pathophysiological functions, it is of great importance to understand the regulation of their hormone secretion process. A key element to such an understanding is the identification of the location of the "inverting step," which makes the parathyroid cells behave in a fashion contrary to most other secretory cells. Whole cell imaging studies strongly suggested that the inversion factor is between the changes in intracellular calcium concentration ([Ca2+]i) and the secretion of the hormone. Surprisingly, confocal calcium imaging of the parathyroid cells did not support this dogma. It revealed that the interior of the parathyroid cell is a nonhomogeneous medium and that an increase in the extra-cellular calcium concentration produces changes in [Ca2+]i, in both the same and opposite directions, in different parts of the parathyroid cell.

Animals↗
PubMed1997

[Centenary of Becquerel. The main stages of discovery and use of radionuclides (1896-1996)].

The french scientists Henri Becquerel, Pierre and Marie Curie, Frédéric and Irène Joliot-Curie contributed decisively to the discovery and use of radionuclides. Besides them, Antoine Lacassagne, Robert Courrier, Pierre Süe developed the research in Chemistry and Biology. After 1945, medical applications were initiated by Charlie Fisher, Maurice Tubiana, Henri Jammet, in France. Marcel Guillot, student and assistant of Marie Curie, pharmacist himself, inserted pharmacists in research, development, control and teaching of medical radionuclides. Marcel Guillot defined the first pharmaceutical regulations and worked out the first monographs in french and european pharmacopoeias.

Drug Utilization↗
PubMed1997

The number of Israeli immigrants in the United States in 1990.

In this paper we estimate the size of several categories of "Israeli" immigrants in the United States. According to the 1990 U.S. census, there were about 95,000 Israeli-born immigrants in the United States in that year. Using the language and ancestry information available in the Public Use Microdata Sample (PUMS) of the 1990 census, we estimate that of this total, about 80,000 are Jews and 15,000 are Palestinian Arabs born in Israel. In addition to the Israeli-born, we present a range for the number of Jewish immigrants from Israel who are not Israeli-born (about 30,000-56,000). Thus our estimate for the total number of Jewish immigrants from Israel in the United States in 1990 is between 110,000 and 135,000. Fertility information available in the PUMS, also enable us to provide estimates for the number of second-generation Israelis in the United States in the 1990 (about 42,000). Finally, using both the 1980 and 1990 PUMS, we provide estimates for the rate of return migration among Israeli-born Jewish immigrants in the United States.

Algorithms↗
PubMed1996

[Primary brain tumors].

In our retrospective analysis of 305 patients with primary brain tumors, treated and followed at Rambam Medical Center between 1983-1990, 56% were males; mean age was 43; 47% were Ashkenazi Jews, 22% Sephardi Jews, 22% Arabs and 9% were Jews of unspecified origin. 3-year actuarial survival for all patients was 33.5%, Arabs 51%, Sephardi Jews 40%, Ashkenazi Jews 20%; for those younger than 20, it was 57%, and older than 20, 26%. Diagnoses were: astrocytoma grades I-II, 68%; astrocytoma grade III, 24%; glioblastoma multiforme, 5.5%; medulloblastoma 73%; ependymoma, 75%; oligodendroglioma, 85%; meningioma, 100%; pituitary adenoma, 100%. Survival probability of those with glioblastoma multiforme treated by combined surgery and radiotherapy was superior to that of those treated by surgery alone. In low-grade astrocytoma there was no difference in survival probability between those with combined therapy and those treated by surgery alone. Survival when the diagnosis was based on imaging studies alone without histological confirmation of malignancy, was similar to that of those with glioblastoma: only 3.0% at 3 years. Prognostic factors identified by univariate analysis were histology, age of patient and ethnic origin, and type of treatment.

Astrocytoma↗
PubMed1996

Application of redox enzymes for probing the antigen-antibody association at monolayer interfaces: development of amperometric immunosensor electrodes.

Insulation of the electrical contact between a redox protein and an electrode surface upon association of an antibody to an antigen monolayer assembled on the electrode is used to develop immunosensor devices. In one configuration, a mixed monolayer consisting of the N epsilon-(2,4-dinitrophenyl)lysine antigen and ferrocene units acting as electron transfer mediators is applied to sense the dinitrophenyl antibody (DNP-Ab) in the presence of glucose oxidase (GOx) and glucose. In the absence of DNP-Ab, the mixed monolayer electrode stimulates the mediated electrocatalyzed oxidation of glucose that results in an amplified amperometric response. Association of the DNP-Ab to the modified electrode blocks the electrocatalytic transformation. The extent of the electrode insulation by the DNP-Ab is controlled by the Ab concentration in the sample. In the second configuration, a N epsilon-(2,4-dinitrophenyl)lysine antigen monolayer assembled on a Au electrode is applied to sense the DNP-Ab in the presence of a redox-modified GOx, exhibiting electrical communication with the electrode surface. Two kinds of redox-modified "electrically wired" GOx are applied: GOx modified by N-(ferrocenylmethyl)caproic acid, Fc-GOx, and a novel electrobiocatalyst generated by reconstitution of apo-GOx with a ferrocene-modified FAD semisynthetic cofactor. Electrocatalytic oxidation of glucose by the electrically wired biocatalysts proceeds in the presence of the antigen monolayer electrode, giving rise to an amplified amperometric signal. The electrocatalytic transformation is blocked upon association of the DNP-Ab to the monolayer electrode. The extent of electrode insulation toward the bioelectrocatalytic oxidation of glucose is controlled by the DNP-Ab concentrations in the samples. The application of biocatalysts for amperometric sensing of antigen-antibody interactions at the electrode surface makes the electrode insensitive to microscopic pinhole defects in the monolayer assembly. The antigen monolayer electrode is applied to sense the DNP-Ab in the concentration range 1-50 micrograms mL-1.

Antigen-Antibody Reactions↗
PubMed1996

The precursor of PsaD assembles into the photosystem I complex in two steps.

The present study addresses the assembly in the chloroplast thylakoid membranes of PsaD, a peripheral membrane protein of the photosystem I complex. Located on the stromal side of the thylakoids, PsaD was found to assemble in vitro into the membranes in its precursor (pre-PsaD) and also in its mature (PsaD) form. Newly assembled unprocessed pre-PsaD was resistant to NaBr and alkaline wash. Yet it was sensitive to proteolytic digestion. In contradistinction, when the assembled precursor was processed, the resulting mature PsaD was resistant to proteases to the same extent as endogenous [correction of endogeneous] PsaD. The accumulation of protease-resistant PsaD in the thylakoids correlated with the increase of mature-PsaD in the membranes. This protection of mature PsaD from proteolysis could not be observed when PsaD was in a soluble form-i.e. not assembled within the thylakoids. The data suggest that pre-PsaD assembles to the membranes and only in a second step processing takes place. The observation that the assembly of pre-PsaD is affected by salts to a much lesser extent than that of mature-PsaD supports a two-step assembly of pre-PsaD.

Hydrolysis↗