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Biomedical subjects

J Levy

Publications and source records attributed to J Levy.

At least 307 records · Page 17Linked to original sources
PubMed1989

Environmental fate of alachlor and metolachlor.

Decision-makers, scientists, and the interested public should be informed what future research and education is needed if a strong pesticide regulatory program is imposed. Recommendations are intended to highlight research gaps. Some may be of general concern and apply to many pesticides. A situation that calls into question the value of many of our management decisions, is the lack of good field-scale experimentation and of logical mechanisms for translating and extrapolating laboratory data to field-scale dimensions. Many experiments were not designed to allow application of basic statistical criteria. High costs often preclude sufficient replication in field-scale experiments so that researchers must make the "no-win" choice between doing one investigation well or doing two or three poorly. The following observations about alachlor and metolachlor are provided: Pysicochemical properties are accurately determined. The herbicides' modes of action and plant selectivity have received a great deal of attention, but gaps remain in defining which of three modes of action are most important. Geographic distribution and extent of residue contamination of surface waters is documented, but groundwater contamination is poorly defined. Any groundwater monitoring protocol should limit the investigation based on sound scientific judgment since a nationwide monitoring network cannot be economically justified. Enough data are needed, however, to allow mathematical model development, verification and validation for a diversity of soil, geographic, climatic, and agricultural management conditions. In view of the importance of adsorption in determining the fate of pesticides, improved methods of determining adsorption coefficients (KD) are needed particularly for very low concentrations. The impact of soil aggregation on adsorption/desorption needs to be examined. The role of temperature and water content in adsorption/desorption processes needs clearer definition. Although volatilization is probably of limited concern for herbicides with Henry's Law constants less than 10(-5), better field-scale methods of estimating volatilization are needed. Lack of clear relationships between laboratory and field investigations is particularly acute in leaching studies. Differentiation between transport rates in the root and vadose zones are limited. Methods of sampling water in the vadose zone await innovative technology. Techniques to confine pesticides to the root zone or to retard their movement beyond the root zone are needed. Management strategies must protect groundwater by curtailing movement or reducing pesticide use. Losses of chloracetanilide herbicides through surface runoff and erosion is poorly documented. When erosion control was linked to soil productivity, use of small plot experiments was probably justified. If improved surface water quality is a goal, small plot findings must be extrapolatable to large watersheds.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetamides↗
PubMed1989

Abnormal cell calcium concentrations in cultured bone cells obtained from femurs of obese and noninsulin-dependent diabetic rats.

Cytoplasmic free calcium concentration [Ca2+]i was quantified in cultured bone cells with osteoblastic characteristics. The cells were obtained from femurs of obese (fa/fa) Wistar-Kyoto rats, from nonobese, noninsulin-dependent diabetic (NIDD) Sprague Dawley rats, and from their appropriate controls. [Ca2+]i was also determined in bone cells obtained from in vivo insulin-treated NIDD rats. Obese (Wistar Kyoto) rats had increased body weight (313 +/- 13 vs. 249 +/- 4 g; P less than 0.01), decreased femur weights (0.68 +/- 0.05 vs. 0.89 +/- 0.05 g; P less than 0.05), similar glucose levels (148 +/- 5 vs. 139 +/- 3 mg/dl), and higher plasma insulin levels (6.0 +/- 0.5 vs. 0.7 +/- 0.1 ng/ml; P less than 0.01) when compared with their nonobese [(fa/+); (+/+)] littermates. Nonobese, NIDD rats, compared with their appropriate controls (nondiabetic Sprague Dawley rats) had higher plasma glucose levels (235 +/- 32 vs. 145 +/- 3 mg/dl; P less than 0.01) but their plasma insulins, body weights, and femur weights were similar to controls (0.7 +/- 0.1 vs. 0.6 +/- 0.1 ng/ml; 302 +/- 4 vs. 318 +/- 14 g; 0.97 +/- 0.4 vs. 0.98 +/- 0.04 g, respectively). Long-term (4 weeks) daily insulin treatment (2 u/100 g) of the NIDD rats increased their plasma insulin (1.9 ng/ml; P less than 0.05) and body weight (369 +/- 13 g; P less than 0.05) but did not change their plasma glucose levels (225 +/- 5 mg/dl), or femur weights (0.98 +/- 0.4 g).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Glycemic control in gestational diabetes mellitus--how tight is tight enough: small for gestational age versus large for gestational age?

The relationship between optimal levels of glycemic control and perinatal outcome was assessed in a prospective study of 334 gestational diabetic women and 334 subjects matched for control of obesity, race, and parity. All women with gestational diabetes mellitus were instructed in the use of a memory-based reflectance meter. They were treated with the same metabolic goal according to a predetermined protocol. Three groups were identified on the basis of mean blood glucose level throughout pregnancy (low, less than or equal to 86 mg/dl; mid, 87 to 104 mg/dl; and high, greater than or equal to 105 mg/dl). The low group had a significantly higher incidence of small-for-gestational-age infants (20%). In contrast, the incidence of large-for-gestational-age infants was 21-fold higher in the mean blood glucose category than in the low mean blood glucose category (24% vs. 1.4%, p less than 0.0001). An overall incidence of 11% small-for-gestational-age and 12% large-for-gestational-age infants was calculated for the control group. A significantly higher incidence of small-for-gestational-age infants (20% vs. 11%, p less than 0.001) was found between the control and the low category. In the high mean blood glucose category an approximate twofold increase was found in the incidence of large-for-gestational-age infants when compared with the control group (p less than 0.03). No significant difference was found between the control and mean blood glucose categories (87 to 104 mg/dl). Our data suggest that a relationship exists between level of glycemic control and neonatal weight. This information is helpful in targeting the level of glycemic control while optimizing pregnancy outcome in gestational diabetes comparable to the general population.

Blood Glucose↗
PubMed1989

Sex differences in the lateralized processing of facial emotion.

Two reaction time tasks were administered to male and female normal subjects, involving judgments of facial emotion. In the Word-Face task, judgments of similarity or difference of a centrally presented emotion word and an emotional face presented in the left or right visual field were required, and in the Face-Face task, comparisons of a centrally presented and a laterally presented emotional face were required. Results were significant for the matching trials only. Reaction times to negative emotions were faster overall than to positive emotions, and an Emotional Valence by Visual Field interaction was found such that reaction times were faster for negative emotions in the left visual field and for positive emotions in the right visual field. This interaction was significant for the female but not the male subjects, although similar patterns were observed in both sexes. Further, an interaction of Gender, Task, and Emotional Valence was found, such that the two tasks had opposite effects for the two sexes. The Face-Face task appeared to inhibit the performance of the male subjects and facilitate the performance of the female subjects in terms of reaction time. It was suggested that specifying the target emotion by an emotional face elicits a greater emotional response on the part of the subject than specification by a word, and that this emotional elicitation may result in a reactive inhibition in the male subjects and in an elaboration of the emotional response in the female subjects.

Adult↗
PubMed1989

Use of topically applied silver sulphadiazine plus cerium nitrate in major burns.

All patients hospitalized between May 1987 and June 1988 suffering from burns covering over 50 per cent of the body surface area were treated by topical application of a cream containing cerium nitrate (0.05 M) and silver sulphadiazine (0.03 M) (CN + SSD). Eleven patients were included in this series, with a mean age of 35 years (range 22-65), a mean total burn size of 78 per cent (range 50-96 per cent) and full skin thickness covering a mean of 48 per cent (range 10-91 per cent). Eight patients survived (73 per cent) (mean age 36 years; mean total burn surface 73 per cent; mean full skin thickness burn surface, 38 per cent). These results are far better than those obtained in our Unit where a survival rate of 34 per cent was obtained in a comparable series of patients treated before 1987. Sixty positive blood cultures were obtained, which included a large variety of organisms with a slight predominance of Staph. aureus, Candida albicans and Ps. aeruginosa. Wound cultures were positive in 72 per cent of swabs and showed a predominance of Ps. aeruginosa (59 per cent of all the strains isolated). Even if CN + SSD appears in this series not to be very efficient in preventing wound colonization and septic complications, it permitted a very high survival rate in the treated patients, taking into account the extreme severity of the injuries. This beneficial effect is probably the consequence of the protective action of the yellow-green eschar formed by CN + SSD.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1989

Aesthetic preference and picture asymmetries.

Previous research has shown that when right-handed subjects prefer one orientation of a picture over its mirror image, the more interesting or important content is on the right. Location of content, however, is only one of a number of possible asymmetric aspects of picture composition. To determine whether the relationship between aesthetic preference and cerebral asymmetry is affected by the interaction of different aspects of asymmetric information in a slide, the present study examined both asymmetry of content and asymmetry of motion. The results indicated that asymmetry of both content and motion combined to influence orientation preferences of right-but not left-handers. Thus, at least two asymmetric components of picture composition interact with brain organization to influence aesthetic judgements.

Esthetics↗
PubMed1989

Inhibition of growth of human mammary tumor cells by potent antagonists of luteinizing hormone-releasing hormone.

Various studies support the view that analogs of luteinizing hormone-releasing hormone (LH-RH) exert some direct effects on mammary tumor cells. Recently, new LH-RH antagonists [Ac-D-Nal(2)1,D-Phe(pCl)2,D-Trp3,D-Hci6,D-Ala10]-LH-RH (SB-29) and [Ac-D-Nal(2)1,D-Phe(pCl)2,D-Trp3,D-Cit6,D-Ala10]LH-RH (SB-30), which are devoid of edematogenic effects, were synthesized. In this study, we examined whether these LH-RH antagonists inhibit the proliferation of MDA-MB-231 human mammary tumor cells in culture. [3H]Thymidine incorporation into DNA and cell number were measured. The antagonists induced up to 40% inhibition of [3H]thymidine incorporation in MDA-MB-231 cells. This inhibition was dose-dependent in the 0.3-30 microM range and could be demonstrated after 2 days of incubation in the presence of the peptides. An older antagonist, [Ac-D-Phe(pCl)1,2,D-Trp3,D-Arg6,D-Ala10]-LH-RH (ORG 30276), had a lesser effect, and the agonist des-Gly10-[D-Ser(tBu)6]LH-RH ethylamide (buserelin) had no effect. The antagonists SB-29 and SB-30 also inhibited the rate of cell growth, as measured by cell number, while the LH-RH agonist buserelin had no significant effect. These results support the concept that these new LH-RH antagonists can directly inhibit the growth of human mammary tumors and thus might be suitable for the treatment of breast cancer.

Breast Neoplasms↗
PubMed1989

The combined suppression/stimulation therapy in IVF-ET programmes: expectations and facts.

The benefits of combined pituitary suppression/ovarian stimulation therapy in IVF-ET programmes could be avoiding an untimely LH secretion, synchronization of the ovarian response to stimulation, an increased number of ova obtained and embryos replaced and a higher pregnancy rate. The first two advantages can be considered as direct effects of the combined therapy, while the others result, at least partly, from the more aggressive use of gonadotrophins. The capability of combined GnRH analogue/gonadotrophin treatment to avoid failures due to premature luteinization of follicles seems to be unequivocal. In order to obtain a better synchronized ovarian response to stimulation, new treatment schemes, based on prolonged use of currently available agonists or on application of potent synthetic GnRH antagonists, will have to be developed. Basic studies concerning the presence and the extent of a direct effect of GnRH analogues upon ovarian function would also help in a better understanding and more efficient application of the combined suppression/stimulation therapy in IVF-ET programmes.

Embryo Transfer↗
PubMed1989

Cathepsin D-like activity in neutrophils and monocytes.

Monocytes-macrophages and polymorphonuclear leukocytes contain an acid proteolytic enzyme that cleaves tritiated hemoglobin. The monocyte-macrophage-derived enzymatic activity was completely inhibited by pepstatin A, a property of cathepsin D. Monocyte-derived macrophages developed detectable cathepsin D-like activity after 5 days in culture, and this activity coincided with the appearance of other known indicators of macrophage maturation. The cathepsin D activity further increased significantly with time after day 5 of culture. The proteinase activity extracted from neutrophils was only partially inhibitable by pepstatin A, which indicates that this activity is contributed by more than one proteolytic enzyme, including cathepsin D. Cathepsin D activity demonstrated in neutrophils and macrophages may be an important marker of phagocyte function.

Cathepsin D↗
PubMed1989

Voice restoration following laryngectomy: the role of primary versus secondary tracheoesophageal puncture.

A protocol was established at our institution to compare a series of primary and secondary tracheoesophageal punctures using the Singer-Blom voice prosthesis. Over a 24-month period, 20 primary and 18 secondary punctures were performed. Voice production, fluency of voice, and functional use were graded. Our data support the use of both primary and secondary voice restoration following laryngectomy.

Adult↗
PubMed1989

Voice restoration after laryngopharyngoesophagectomy.

Although various methods of alaryngeal communication after laryngectomy have been described, little attention has been given to voice restoration after laryngopharyngoesophagectomy. This article deals with our experience reconstructing the hypopharynx and cervical esophagus in five patients by the use of microvascular free tissue grafts. Voice restoration procedures with use of a Blom-Singer prostheses were used uniformly and resulted in the attainment of functional voice in each patient. It is our feeling that this method should be used equally in patients undergoing both traditional laryngectomy and laryngopharyngoesophagectomy.

Adult↗
PubMed1989

Homophobia and attitudes about AIDS.

A random sample of 407 French Canadian adults responded to a questionnaire about perception of AIDS. Negative attitudes about AIDS are better predicted by homophobia than other measures as are attitudes about extramarital relations and attitudes abut adolescent heterosexuality.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Effect of exercise on the kidney of aging mice.

Quantitative light microscopic and ultrastructural kidney changes were studied in young and old mice subjected to moderate exercise. While there was little or no change in the glomeruli of the young animals, the older age-group showed progressive and statistically significant mesangial sclerosis with obliteration of capillary lumina. Electron microscopy also showed electron dense deposits in both the mesangium and subendothelium. Kidney weight in the young mice subjected to exercise was decreased when compared with the controls, while old animals showed a higher kidney weight after 6 weeks of running exercise. Our results of progressive kidney changes in old exercising animals, together with previous studies on myocardial and skeletal muscle showing parallel changes, stress the need for careful clinical studies on the possible damage of these organs in older people who engage in jogging and heavy exercise.

Aging↗
PubMed1988

Properties of a human insulin receptor with a COOH-terminal truncation. I. Insulin binding, autophosphorylation, and endocytosis.

In order to test the contribution of the insulin receptor COOH terminus to insulin action, a truncation of 43 COOH-terminal amino acids was engineered by cDNA-based deletion mutagenesis. This cDNA (HIR delta CT), as well as cDNA encoding the complete receptor (HIRc) was transfected into Rat 1 fibroblasts. Cells expressing 6.4 X 10(3) and 1.25 X 10(6) normal receptors and 2.5 X 10(5) HIR delta CT receptors, as well as control Rat 1 fibroblasts were selected for further analysis. All cell lines exhibited insulin binding of similar affinity. Partial tryptic digestion and immunoprecipitation by region-specific antibodies verified that the HIR delta CT receptors were truncated at the COOH terminus. Purified HIRc and HIR delta CT receptors underwent autophosphorylation with similar insulin and ATP sensitivity, although the HIR delta CT receptors were slightly more active in the absence of insulin. Transfected HIRc and HIR delta CT receptors undergo endocytosis in a normal fashion. Insulin internalization and degradation in both HIRc and HIR delta CT cells is increased in proportion to receptor number. Intracellular insulin processing, degradation, and release were qualitatively comparable among the transfected cell lines. Complete and truncated receptors internalize, recycle, and down-regulate normally. We conclude the following: 1) the COOH-terminal portion of the insulin receptor is not necessary for partial autophosphorylation or endocytosis; 2) following internalization the intracellular itinerary of the receptor and ligand appear normal with the truncated receptor; and 3) truncation of the COOH terminus does not impair recycling of the receptor or retroendocytosis of internalized ligand.

Animals↗