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Biomedical subjects

G Lester

Publications and source records attributed to G Lester.

At least 19 recordsLinked to original sources
PubMed2003

On-farm and postharvest processing sources of bacterial contamination to melon rinds.

Multistate and international foodborne illness outbreaks, particularly involving cantaloupe and often involving rare Salmonella spp., have increased dramatically over the past 13 years. This study assessed the sources and extent of melon rind contamination in production fields and at processing and packing facilities. In the spring of 1999, cantaloupe (Cucumis melo L. [reticulatus group] cv. Cruiser) sampled from two sites in the Rio Grande River Valley showed that postharvest-processed melon rinds often had greater plate counts of bacterial contaminants than field-fresh melons. Cantaloupe in the field had 2.5 to 3.5 log CFU g(-1) rind total coliforms by aerobic plate counts, whereas washed melons had 4.0 to 5.0 log CFU g(-1). In the fall of 1999, coliforms on honeydew melons (C. melo [inodorous group] cv. Honey Brew) ranged from 2.6 to 3.7 log CFU g(-1) after processing, and total and fecal coliforms and enterococci never fell below 2.5 log CFU g(-1). A hydrocooler at another site contaminated cantaloupe rinds with up to 3.4 log CFU g(-1) total and fecal enterococci; a secondary rinse with chlorinated water incompletely removed these bacteria. Sources of coliforms and enterococci were at high levels in melon production soils, especially in furrows that were flood irrigated, in standing water at one field, and in irrigation water at both sites. At one processing facility, wash water pumped from the Rio Grande River may not have been sufficiently disinfected prior to use. Because soil, irrigation water, and process water were potential sources of bacterial contamination, monitoring and management on-farm and at processing and packing facilities should focus on water quality as an important control point for growers and packers to reduce bacterial contamination on melon rinds.

Colony Count, Microbial↗
PubMed1999

Effect of timing and route of administration of furosemide on pulmonary hemorrhage and pulmonary arterial pressure in exercising thoroughbred racehorses.

OBJECTIVES: To examine effect of pre-exercise administration of furosemide (FUR) on mean pulmonary arterial pressure (PAP) during work and RBC concentration in bronchoalveolar lavage fluid (BALF) collected 40 minutes after exercise. ANIMALS: 10 adult Thoroughbreds. PROCEDURE: A modified 10 X 10 crossover design comprising 10 horses during 10 weeks was used. Each horse received each of 5 treatments twice. Treatment structure included a control plus a 2 X 2 factorial and consisted of the following: A, control; B, FUR, 250 mg, IV, 30 minutes before exercise; C, FUR, 250 mg, IV, 240 minutes before exercise; D, FUR, 250 mg, nebulized, 30 minutes before exercise; and E, FUR, 250 mg, nebulized, 240 minutes before exercise. Mean PAP data were collected, and each horse, after a 500-m warm-up, was galloped at maximal speed for 1,600 m. BALF RBC concentration was determined by hemocytometer. RESULTS: Interaction between treatment method and time of administration was significant (P = 0.04). Treatment B resulted in significantly (P = 0.01) lower BALF RBC concentration than did treatment C. Only BALF RBC count after treatment B was significantly lower than the control value. Horses that received FUR IV had significantly lower peak mean PAP than did those that received the drug by nebulization, regardless of administration time. Only treatment B resulted in peak mean PAP that was significantly lower than that of control. Exercise time was not influenced by treatment. CONCLUSIONS: FUR, administered IV 30 minutes before exercise, significantly reduced peak mean PAP and BALF RBC concentration.

Animals↗
PubMed1997

Vitamin D levels in children with cystic fibrosis.

Serum levels of the important hormone 1,25-dihydroxyvitamin D (1,25-diOHD, calcitriol) have not been extensively evaluated in patients with cystic fibrosis (CF) during the critical period of skeletal growth and development. This study was a cross-sectional, observational assessment of 25-hydroxyvitamin D (25-OHD, calcidiol) and 1,25-diOHD levels in 54 patients with CF. The patients' ages ranged from 4.9 years to 19.5 years (mean, 11.0 years). Levels were correlated with pulmonary function tests, chest x-ray scores, height and weight Z scores, skinfold percentiles, CF genotype, serum chemistries, and use of a vitamin supplement. Levels were compared with those in more than 160 other pediatric patients living in the same region, and all assays were done in the same laboratory. Despite low-normal levels of the 25-OHD precursor, there was a high prevalence of low (18%) and marginal (18%) levels of 1,25-diOHD. None of the various parameters examined correlated with either 25-OHD or 1,25-diOHD levels. The cause, clinical significance, and treatment of low levels of this important hormone in children with CF warrant further study.

Adolescent↗
PubMed1991

Bone mineral content at three sites in normal perimenopausal women.

Bone mineral content (BMC) in 217 healthy white women between the ages of 40 and 55 years was measured using single- and dual-photon absorptiometry. The sites measured included the distal radius, midradius, proximal femur, and lumbar spine. The relationship between BMC and age was constant over the age range studied when the confounding effect of menopause was controlled. Women with low body mass indices (BMIs) had significantly lower BMC than women with average or greater than average BMIs. More active women had higher BMC than less active women at both appendicular and axial sites. A trend suggesting that women with higher calcium intake may have higher BMC was statistically significant only at the midradial site. A trend of postmenopausal women having lower BMC than pre- or perimenopausal women was also statistically significant only at the midradial site. Only modest correlations were found between the various sites. These correlations are too weak to allow accurate clinical predictions of BMC at axial sites from the BMC at an appendicular site in individual patients.

Absorptiometry, Photon↗
PubMed1982

Acquired postganglionic cholinergic dysautonomia: case report and review of the literature.

An 8-year-old girl with acute abdominal pain had cholinergic autonomic dysfunction. There have been only four patients with acquired postganglionic cholinergic dysautonomia described in the literature. The characteristic clinical features are atony of the bowel and bladder, lack of tears, saliva, and sweat, internal ophthalmoplegia, and normal adrenergic functions. Special studies for autonomic nervous function help in confirming this diagnosis. The exact pathogenesis of the disorder is still not clear. This case demonstrates successful treatment with bethanechol chloride.

Autonomic Nervous System Diseases↗
PubMed1979

The corporate executive wife's coping patterns in response to routine husband-father absence.

The routine absence of corporate executive husband/fathers in intact families is a variation of father absence. Though not prolonged, frequent exits and reentries may stress the family system. To determine how nonclinical family members deal with routine father absence, a coping inventory was administered to 66 corporate wives. Factor analysis revealed wives coped with the stress of routine father absence by (a) fitting into the corporate lifestyle; (b) developing self; and (c) establishing independence. Though a pilot study, findings offer empirical support for a premise more traditionally accepted by family therapists than by family sociologists: Individual psychological variables need to be considered along with systems variables in the development of family stress theory.

Adaptation, Psychological↗
PubMed1974

Isolation and characterization of low-kynureninase mutants of Neurospora crassa.

Two kynureninase activities are known in Neurospora crassa, one of which (kynureninase I) is inducible, the other (kynureninase II) being constitutive. A method is described for the isolation of low-kynureninase mutants of N. crassa. When grown on an inducer, the mutants show significantly less kynureninase I activity compared with wild type, whereas constitutive kynureninase II activity is unaffected. Since a low level of kynureninase I activity remains in the mutants examined, the mutations may be in a regulatory gene or genes. Other experiments are described concerning the molecular weights of the two enzymes and the intracellular localization and specificity of kynureninase II.

Chromatography, DEAE-Cellulose↗
PubMed1971

Properties of an extracellular -galactosidase secreted by Neurospora crassa.

An extracellular beta-galactosidase with an activity optimum at about pH 4 was found to occur in the filtrates of Neurospora crassa strain 74A when this mold was grown on certain sugars. This activity accounted for a substantial portion of the beta-galactosidase activity in the culture. The beta-galactosidase in the medium appeared to be a secreted, extracellular enzyme, not a product of cell lysis. The extracellular activity was found to have physical and kinetic properties similar to those of an intracellular beta-galactosidase previously found in Neurospora. Some conditions for the production and concentration of the enzyme are described.

Carbohydrate Metabolism↗
PubMed1971

Regulation of tryptophan biosynthetic enzymes in Neurospora crassa.

The formation of enzymatic activities involved in the biosynthesis of tryptophan in Neurospora crassa was examined under various conditions in several strains. With growth-limiting tryptophan, the formation of four enzymatic activities, anthranilic acid synthetase (AAS), anthranilate-5-phosphoribosylpyrophosphate phosphoribosyl transferase (PRAT), indoleglycerol phosphate synthetase (InGPS), and tryptophan synthetase (TS) did not occur coordinately. AAS and TS activities began to increase immediately, whereas PRAT and InGPS activities began to increase only after 6 to 12 hr of incubation. In the presence of amitrole (3-amino-1,2,4-triazole), the formation of TS activity in a wild-type strain was more greatly enhanced than were AAS and InGPS activities. With a tr-3 mutant, which ordinarily exhibits an elevated TS activity, amitrole did not produce an increase in TS activity greater than that observed on limiting tryptophan. With tr-3 mutants, the increased levels of TS activity could be correlated with the accumulation of indoleglycerol in the medium; prior genetic blocks which prevented or reduced the synthesis of indoleglycerol also reduced the formation of TS activity. The addition of indoleglycerol to cultures of a double mutant (tr-1, tr-3) which could not synthesize indoleglycerol markedly stimulated the production of TS activity but not PRAT activity; the production of TS activity reached the same level with limiting or with excess tryptophan. A model explaining these and other related observations on enzyme formation in N. crassa is proposed.

Cell-Free System↗
PubMed1971

End-product regulation of the tryptophan-nicotinic acid pathway in Neurospora crassa.

The regulation of the tryptophan-nicotinic acid pathway in Neurospora crassa was examined with mutants (nic-2, nic-3) which require nicotinamide for growth. The accumulation of N-acetylkynurenin and 3-hydroxyanthranilic acid by these mutants served to estimate the level of function of the early reactions in the pathway. In still cultures, maximal accumulation occurred with media containing growth-limiting amounts of nicotinamide; the accumulation of intermediates was almost negligible with nicotinamide in excess. Only nicotinamide and closely related compounds which also supported the growth of these mutants inhibited the accumulation of intermediates. The site of inhibition was assessed to be between tryptophan and kynurenin (or N-acetylkynurenin). The synthesis of N-acetylkynurenin was examined in washed germinated conidia suspended in buffer; the level of N-acetylkynurenin-synthesizing activity was inversely related to the concentration of nicotinamide in the germination medium. The addition of large amounts of nicotinamide to suspensions of germinated conidia did not affect their N-acetylkynurenin-synthesizing activity. Formamidase activity, kynurenin-acetylating activity, and gross tryptophan metabolism in germinated conidia was not influenced by the concentration of nicotinamide in the germination medium. The results obtained indicate that the site of inhibition by nicotinamide is the first step in the pathway, the tryptophan pyrrolase reaction. The data are interpreted as nicotinamide or a product thereof, such as nicotinamide adenine dinucleotide, acting as a repressor of the formation of tryptophan pyrrolase in N. crassa.

Arylformamidase↗