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Biomedical subjects

A Blumenfeld

Publications and source records attributed to A Blumenfeld.

At least 55 records · Page 3Linked to original sources
PubMed1994

The neurobehavioral cognitive status examination as a screening tool for organicity in psychiatric patients.

OBJECTIVE: The study explored the efficiency of the Neurobehavioral Cognitive Status Examination (NCSE) in predicting organic pathology in psychiatric patients. METHODS: Based on history of neurological disorders, 192 psychiatric patients at a country hospital were assigned to one of two groups according to whether they did or did not have organic mental disorder. Fifty patients were determined to have the disorder, and 136 were determined not to have the disorder. The patient's performance on each of the NCSE's ten scales was rated from 1, indicating average performance, to 4, indicating severe impairment. The scores were added together to form a composite index score, with a range from 10 to 40. Composite scores for the two groups were compared. RESULTS: A composite index score of 13 was optimal for discriminating between patients with organic mental disorder and those without the disorder. At this cutoff level, the test had a sensitivity of .72 and specificity of .73. CONCLUSIONS: The NCSE can be useful in screening for organicity in a psychiatric population. However, psychiatric patients without organic mental disorder can be expected to demonstrate some impairment on one or more of the NCSE's ten scales.

Adolescent↗
PubMed1993

Localization of the gene for familial dysautonomia on chromosome 9 and definition of DNA markers for genetic diagnosis.

Familial dysautonomia (DYS), the Riley-Day syndrome, is an autosomal recessive disorder characterized by developmental loss of neurons from the sensory and autonomic nervous system. It is limited to the Ashkenazi Jewish population, where the carrier frequency is 1 in 30. We have mapped the DYS gene to chromosome 9q31-q33 by linkage with ten DNA markers in 26 families. The maximum lod score of 21.1 with no recombinants was achieved with D9S58. This marker also showed strong linkage disequilibrium with DYS, with one allele present on 73% of affected chromosomes compared to 5.4% of controls (chi 2 = 3142, 15 d.f. p < 0.0001). D9S53 and D9S105 represent the closest flanking markers for the disease gene. This localization will permit prenatal diagnosis of DYS in affected families and aid the isolation of the disease gene.

Alleles↗
PubMed1993

Exclusion of familial dysautonomia from more than 60% of the genome.

Familial dysautonomia (FD) is a recessive neurological disorder that affects the development of the sensory and autonomic nervous system. The gene defect appears to be limited to the Ashkenazi Jewish population, where the carrier frequency is 1 in 30. One hundred and ninety-one marker loci representing all autosomes were tested for linkage with the FD genetic defect in 23 families. A combination of pairwise and multipoint analyses excluded the FD gene from at least 60% of the autosomal genome. The program EXCLUDE predicted regions of chromosomes 2, 4, 5q, 9, or 10 as the most promising locations for future analyses.

Chromosome Mapping↗
PubMed1992

[Ascaris lumbricoides--a cause of acute abdomen].

Ascaris lumbricoides infestation is the most common helminthic disease in many developing countries and may cause severe surgical complications, especially in children. We present a 3-year-old Ethiopian immigrant brought to hospital directly from the airport because of signs of acute abdomen. It was found to be caused by volvulus and necrosis of a loop of bowel impacted with worms. The necrotic bowel loop was resected and a temporary ileostomy was formed; recovery was uneventful. This disease and its severe complications are rare in Israel and the western world. Awareness of its occurrence is important in view of the present world-wide large-scale immigration from developing countries.

Abdomen, Acute↗
PubMed1990

Adjunctive therapy with bromocriptine in Parkinson's disease.

Patients with moderately severe Parkinson's disease complicated by the adverse effects of chronic levodopa use benefited from the addition of bromocriptine (Parlodel; Sandoz) in doses up to 26 mg daily, which allowed an approximate 30% reduction of levodopa dose. This resulted in a significant decrease in the amount of levodopa side-effects while maintaining or improving the original parkinsonian clinical stage. Increased effectiveness in these patients was not associated with increased dosage beyond 25-30 mg daily. When the doses of bromocriptine were increased slowly, the adverse reactions were minor and usually transient.

Adult↗
PubMed1990

Human immunodeficiency virus (HIV)-associated myopathy: immunocytochemical identification of an HIV antigen (gp 41) in muscle macrophages.

In a patient with acquired immunodeficiency disease syndrome (AIDS) and muscle weakness, a muscle biopsy specimen disclosed degeneration of muscle fibers, regeneration, and focal endomysial mononuclear inflammation. A conspicuous feature was the presence of perivascular macrophages within the endomysium that showed positive immunostaining for human immunodeficiency virus (HIV) (gp 41) antigen. HIV was not detected within myofibers. Our findings suggest an important role for the HIV-infected macrophage in the pathogenesis of this myopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Interference of phenolic compounds with the 1-aminocyclopropane-1-carboxylic Acid assay.

The yields of ethylene from endogenous and exogenous 1-aminocyclo-propane-1-carboxylic acid (ACC) in avocado (Persea Americana Mill.) fruit pedicel extracts were very low when assayed by the method of Lizada and Yang (1979 Anal Biochem 100: 140-145). Addition of phenolic compounds, which are present in avocado tissues, to the assay mixture significantly reduced the conversion efficiency of ACC to ethylene. A negative correlation was found between the amount of the plant material in the assay mixture and the conversion efficiency of ACC to ethylene. Removal of phenolic compounds from pedicel extracts by polyvinylpolypyrrolidone, Amberlite XAD-7, and Dowex-50 column chromatography or lead acetate precipitation greatly increased the yields of thylene from ACC in these extracts. The use of polyvinylpolypyrrolidone column chromatography also enabled us to obtain more accurate estimations of endogenous ACC levels in carnation (Dianthus caryophyllus L.) petal extracts. The conversion efficiency of ACC to ethylene could be improved by increasing the concentrations of mercuric chloride and NaOCl in the assay mixture.

Journal Article↗
PubMed1987

Coupling of photoexcited rhodopsin to inositol phospholipid hydrolysis in fly photoreceptors.

Fly photoreceptor membranes were used to test the effect on defined biochemical reactions of light and of compounds causing photoreceptor excitation. Complementary electrophysiological studies examined whether putative second messengers excite the fly photoreceptor cells. This analysis revealed the following sequence of events: photoexcited rhodopsin activates a G protein by facilitating GTP binding. The G protein then activates a phospholipase C that generates inositol trisphosphate, which in turn acts as an internal messenger to bring about depolarization of the photoreceptor cell. Binding assays of GTP analogs and measurements of GTPase activity showed that there are 1.6 million copies of G protein per photoreceptor cell. The GTP binding component is a 41-kDa protein, and the light-activated GTPase is dependent on photoconversion of rhodopsin to metarhodopsin. Analysis of phospholipase C activity revealed that this enzyme is under stringent control of the G protein, that the major product formed is inositol trisphosphate, and that this product is rapidly hydrolyzed by a specific phosphomonoesterase. Introduction of inositol trisphosphate to the intact photoreceptor cell mimics the effect of light, and bisphosphoglycerate, which inhibits inositol trisphosphate hydrolysis, enhances the effects of inositol trisphosphate and of dim light. The interaction of photoexcited rhodopsin with a G protein is thus similar in both vertebrate and invertebrate photoreceptors. These G proteins, however, activate different photoreceptor enzymes: phospholipase C in invertebrates and cGMP phosphodiesterase in vertebrates.

Animals↗
PubMed1986

Regulation of Ethylene Biosynthesis in Avocado Fruit during Ripening.

Preclimacteric avocado (Persea americana Mill.) fruits produced very little ethylene and had only a trace amount of l-aminocyclopropane-1-carboxylic acid (ACC) and a very low activity of ACC synthase. In contrast, a significant amount of l-(malonylamino)cyclopropane-1-carboxylic acid (MACC) was detected during the preclimacteric stage. In harvested fruits, both ACC synthase activity and the level of ACC increased markedly during the climacteric rise reaching a peak shortly before the climacteric peak. The level of MACC also increased at the climacteric stage. Cycloheximide and cordycepin inhibited the synthesis of ACC synthase in discs excised from preclimacteric fruits. A low but measurable ethylene forming enzyme (EFE) activity was detected during the preclimacteric stage. During ripening, EFE activity increased only at the beginning of the climacteric rise. ACC synthase and EFE activities and the ACC level declined rapidly after the climacteric peak. Application of ACC to attached or detached fruits resulted in increased ethylene production and ripening of the fruits. Exogenous ethylene stimulated EFE activity in intact fruits prior to the increase in ethylene production. The data suggest that conversion of S-adenosylmethionine to ACC is the major factor limiting ethylene production during the preclimacteric stage. ACC synthase is first synthesized during ripening and this leads to the production of ethylene which in turn induces an additional increase in ACC synthase activity. Only when ethylene reaches a certain level does it induce increased EFE activity.

Journal Article↗
PubMed1985

Light-activated guanosinetriphosphatase in Musca eye membranes resembles the prolonged depolarizing afterpotential in photoreceptor cells.

Measurement of light-dependent GTPase (EC 3.1.5.1) activity in a paradigm guided by electrophysiological experiments was used to examine the involvement of a guanine nucleotide binding protein in fly phototransduction. Cell-free membrane preparations of Musca eyes responded to blue light by a 10- to 20-fold increase in GTP-hydrolyzing activity. This light-dependent GTPase had a low Km for GTP (0.5 microM) and was effectively inhibited by guanosine (5'----O3)-1-thiotriphosphate and guanosine 5'-[beta-gamma-imino]triphosphate but not by adenosine 5'-[beta-gamma-imino]triphosphate and ATP. The action spectrum of GTPase activity measured with intense light resembled closely the photoequilibrium spectrum of metarhodopsin. After illumination with blue (less than 480 nm) light, which converted rhodopsin to metarhodopsin, the GTPase remained highly active for at least 60 min in the dark. Similarly, rhodopsin-to-metarhodopsin conversion in intact cells induced a prolonged excitation in the dark, known as the prolonged depolarizing afterpotential (PDA). The persistent GTPase activity (like the PDA) was suppressed to the low basal activity of the unilluminated membranes after conversion of metarhodopsin to rhodopsin with red light (greater than 570 nm), whereas during illumination with red light, some GTPase activity was maintained. The magnitude of the persistent GTPase activity in the dark, like the PDA, depended in a supralinear manner on the amount of pigment conversion. Thus, the dependence of GTPase activity of Musca membrane preparations on photopigment conversion resembles the induction and suppression of the PDA measured in intact photoreceptors of Musca. These findings indicate that a guanine nucleotide binding protein is part of the chain of events leading to both the generation of the receptor potential and the PDA.

Animals↗
PubMed1977

Hormonal activity in detached lettuce leaves as affected by leaf water content.

The interrelationship between water deficiency and hormonal makeup in plants was investigated in detached leaves of romaine lettuce (Lactuca sativa L. cv. ;Hazera Yellow'). Water stress was imposed by desiccating the leaves for several hours in light or darkness at different air temperatures and relative humidity. In the course of desiccation, a rise in abscisic acid content and a decline in gibberellin and cytokinin activity were observed by gas-liquid chromatography, by both the barley endosperm bioassay and radioimmunoassay and by the soybean callus bioassay. Gibberellin activity began to decline in the stressed leaves before the rise in abscisic acid, the rate of this decline being positively correlated with the rate of increase in leaf water saturation deficit. Recovery from water stress was effected by immersing the leaf petioles in water while exposing the blades to high relative humidity. This resulted in a decrease in leaf water saturation deficit, a reduction in abscisic acid content, and an increase in gibberellin and cytokinin activity.Application of abscisic acid to the leaves caused partial stomatal closure in turgid lettuce leaves, whereas treatment with gibberellic acid and kinetin of such leaves had no effect on the stomatal aperture. In desiccating leaves, however, gibberellic acid and kinetin treatment considerably retarded stomatal closure, thus enhancing the increase in leaf water saturation deficit. These results suggest that the effect of desiccation in changing leaf hormonal make-up, i.e. a rapid increase in abscisic acid and a decrease in both cytokinin and gibberellin activity, is related to a mechanism designed to curtail water loss under conditions inducing water deficiency.

Journal Article↗
PubMed1975

Ethylene and the annona flower.

The annona (Annona hybrida) flower is protogynous, and reaches its male stage about 26 hours after the beginning of the female stage. A rise in ethylene production was found to precede the male stage. Much more ethylene was produced by the reproductive organs than by the petals, with the anthers producing most of the ethylene. Ethylene treatments advanced the male stage, but not the female stage. Exposing flowers to hypobaric pressure postponed the onset of their male stage. Application of various growth substances causing ethylene production by the flower advanced the male stage.

Journal Article↗