Mutagenic effect on L5178Y mouse lymphoma cells by growth in ethylene oxide-sterilized polycarbonate flasks.

The mutation frequency of L5178Y mouse lymphoma cells to resistance to 5'-bromo-2'-deoxyuridine increased 6- to 14-fold after growth in ethylene oxide-sterilized polycarbonate culture flasks compared to growth in glass flasks. No comparable increase was observed when L5178Y cells were grown in identical polycarbonate culture flasks sterilized by autoclaving.     

Recent observations on the ultrastructure of human urothelium

Summary An electron microscopic study of normal bladder urothelium of elderly patients ranging in age from 61 to 82 years has shown the occurrence of unusually thin regions consisting of either one or two layers of undifferentiated cells interspersed between 3–4 cell layers thick regions. A morphometric study has confirmed the existence of a pattern of cytodifferentiation in cells of the thick region. The generally microvillous nature of the luminal surface is attributed to incompletely differentiated cells that have come to occupy the superficial layer. The lack of thickened and/or asymmetric membrane plaques in luminal plasma as well as the dearth of characteristic precursor vesicles in the cytoplasm are also explicable in terms of a failure of normal cell differentiation. It is suggested that the unusual features noted are consequences of tissue ageing rather than prognostic of cancer. There are indications that the aged urothelium may be prone to increased leakiness and the bladder tissues may therefore be at greater risk from urine-borne chemicals and carcinogens.     

Genetic and Behavioral Determinants of Waist-Hip Ratio and Waist Circumference in Women Twins

ROSE, KATHRYN M, BETH NEWMAN, ELIZABETH J. MAYER-DAVIS, JOSEPH V. SELBY. Genetic and behavioral determinants of waist-hip ratio and waist circumference in women twins. Obes Res. 1998;6:383–392. Objectives : This study examines genetic and behavioral determinants of waist-hip ratio (WHR) and waist circumference among women twins. Research Methods and Procedures : Six hundred eighty participants from the second examination of the Kaiser-Permanente Women Twins Study (1989 to 1990) were included. Women ranged in age from 31 to 90 years, and included 59% monozygotic and 41% dizygotic twins. Heritabilities of WHR and waist circumference were estimated (range = 0 to 1) using three different statistical methods. Linear regression models that adjusted for the lack of independence within twin pairs were used to assess associations between behavioral variables, WHR, and waist circumference. Results : Age and body mass index-adjusted heritability estimates ranged from 0.36 to 0.61 for WHR and 0.72 to 0.82 for waist circumference. When considered individually, after adjusting for age and body mass index, all behavioral characteristics, except calorie-adjusted fat intake, were significantly (p<0.10) associated with waist circumference and WHR. Greater central adiposity was associated with lower education, higher alcohol consumption, lower physical activity, current cigarette smoking, higher parity, and postmenopausal status without hormone replacement therapy. In multivariate models, these associations persisted, except neither educational attainment nor alcohol intake was significantly associated with waist circumference. In longitudinal analyses, both measures were positively associated with current or recent-past smoking; infrequent or inconsistent physical activity; and long-term, daily consumption of alcohol. Discussion : These cross-sectional and longitudinal associations are consistent with genetic and behavioral predictors of waist circumference and WHR. Whereas the evidence for genetic influences is stronger for waist circumference, both body fat measures may be similarly influenced by the behavioral factors considered.     

The influence of culture vessel head-space volatiles on somatic embryo maturation in Sitka spruce [Picea sitchensis (Bong.) Carr.]

The maturation of somatic embryos of Sitka spruce [Picea sitchensis (Bong.) Carr.] was found to be highly dependent on the method used to seal plastic Petri dishes. Large numbers of well-formed mature embryos developed if dishes were sealed with PVC cling-film (CF) whilst sealing with Parafilm M (PF) greatly reduced the numbers of embryos forming. Inclusion of potassium permanganate oxidation traps, normally used to deplete the atmospheric ethylene, greatly stimulated somatic embryo maturation under PF sealing. Similarly, traps of adsorption agents (Tenax, activated charcoal or soft white paraffin), capable of removing volatiles from the culture vessel head-space, stimulated somatic embryo maturation under PF sealing although to a lesser extent than the oxidation traps. Incorporation of silver nitrate or 2-chloroethylphosphonic acid (ethephon) in the culture medium indicated that ethylene was not the agent supressing somatic embryo maturation under PF sealing.Abbreviations ABA abscisic acid - CF PVC cling-film - PF Parafilm M     

In vivo neutrophil sequestration within lungs of humans is determined by in vitro "filterability".

Neutrophils are normally delayed in transit through the lung microcirculation, relative to the passage of erythrocytes. This sequestration contributes to a pulmonary pool of neutrophils that may relate to the relative inability of neutrophils to deform compared with erythrocytes when in transit in the pulmonary capillaries. A micropore membrane was used to model the human pulmonary microcirculation, in which cell deformability was measured as the pressure developed during filtration of the cells through the membrane at a constant flow. We demonstrated a significant correlation between in vitro deformability and in vivo lung sequestration of indium-111-labeled neutrophils in 10 normal subjects (r = 0.69, P less than 0.02). In eight patients with stable chronic obstructive pulmonary disease, this relationship was not significant (r = -0.2, P greater than 0.05). Furthermore, in a subject with microscopic pulmonary telangiectasia known to allow significant passage of 30-microns microspheres, neutrophils passed through the lungs without delay. Moreover, neutrophils from patients studied acutely with an exacerbation of chronic obstructive pulmonary disease were temporarily less deformable (P less than 0.01). These studies confirm that cell deformability is an important determinant of the normal neutrophil sequestration within the lungs. Changes in cell deformability may alter the extent of this sequestration.     

A late quarternary lake in the central Namib desert,Southern Africa,and some implications

Lake bed carbonates from Narabeb in the central Namib Desert have been dated by the ²³⁴U/²³⁰Th method at between 210 000 and 240 000 years. Their survival on the ground surface implies that the climate has been arid since this time, and this is interpreted as confirming the hypothesis that the Benguela Current has maintained its influence over the climate of this area throughout the last two glacials.     

Reduction and mutagenic activation of nitroaromatic compounds by a Mycobacterium sp.

Mycobacterium sp. strain Pyr-1 cells, which were grown to the stationary phase in media with and without pyrene, were centrifuged and resuspended in a medium containing 1-nitropyrene. Cells that had been grown with pyrene oxidized up to 20% of the added 1-nitropyrene to 1-nitropyrene-cis-9,10- and 4,5-dihydrodiols. However, cells that had been grown without pyrene reduced up to 70% of the 1-nitropyrene to 1-aminopyrene but did not produce dihydrodiols. The nitroreductase activity was oxygen insensitive, intracellular, and inducible by nitro compounds. Nitroreductase activity was inhibited by p-chlorobenzoic acid, o-iodosobenzoic acid, menadione, dicumarol, and antimycin A. Extracts from cells that had been grown without pyrene activated 1-nitropyrene, 1-amino-7-nitrofluorene, 2,7-dinitro-9-fluorenone, 1,3-dinitropyrene, 1,6-dinitropyrene, and 6-nitrochrysene to DNA-damaging products, as shown in Salmonella typhimurium tester strains by the reversion assay and by induction of the umuC gene. Activation of nitro compounds, as shown by the umu test, was enhanced by NADPH. This study shows that Mycobacterium sp. strain Pyr-1 metabolizes nitroaromatic compounds by both oxidative and reductive pathways. During reduction, it generates products that are mutagenic.