Hyperthermia inhibits the repair of DNA double-strand breaks induced by ionizing radiation as determined by pulsed-field gel electrophoresis.

Hyperthermia is known to synergistically interact with X-rays to kill cells. We have used pulsed-field gel electrophoresis to investigate the effects of hyperthermia on cell survival and on repair of radiation-induced DNA double-strand breaks (dsbs). Combining hyperthermia (43 degrees C, 45 min) with radiation (7.

Cellular deformability of normoxic and hypoxic mammalian red blood cells.

The deformability of red blood cells is important in the microcirculation where capillary diameters are often smaller than those of the red blood cells. In the present study, ektacytometry was used to examine the effect of hypoxia on the deformability of red blood cells from five mammalian species: Human, cat, rat, rabbit, and dog. Deformability was characterized in both normoxic (PO2 = 129 +/- 6 mm Hg) and hypoxic (PO2 = 47 +/- 6 mm Hg) conditions in two different ways.

A laboratory exercise in somesthesis that is expeditious, inexpensive, and suitable for large classes.

A teaching laboratory is described that demonstrates two principles of the somatosensory system: 1) the "spot-like" nature of skin sensitivity and 2) tactile acuity. This laboratory has been used for a large medical school class (140-160 students). One reason for the success of this laboratory is the ability to provide a sufficient number of stimulating apparatuses.

Preferential activity of dentate neurons during limb movements guided by vision.

1. We recorded the activity of dentate neurons while monkeys (n = 2) performed sequential pointing movements under two task conditions: visually guided and remembered. For both conditions, a monkey faced a panel with five touch pads.

Anticipatory guidance for the adolescent. Parents' concerns.

Parents' opinions regarding anticipatory guidance for adolescents have not been adequately investigated. In this study, 932 parents of adolescents completed a computerized questionnaire listing 30 common psychosocial-medical concerns of adolescence. Respondents were asked how important it is for private pediatricians to discuss these topics with their teenagers during regular checkups.

Infant ventilation and oxygenation by basic life support providers: comparison of methods.

Introduction: Little information is available in the performance of infant ventilation by basic life support (BLS) personnel.

Hypothesis: There are no significant differences between mouth-to-mouth (M-M), mouth-to-mask (M-Ma), pediatric bag-mask (PBM), and adult bag-mask (ABM) devices in the percent of acceptable breaths delivered by BLS providers.

Methods: Fifty certified BLS providers performed five ventilation methods in random sequences for 60 seconds each on a 5kg infant mannequin following standardized instructions.

Effect of positive end-expiratory pressure on alveolar capillary perfusion.

Positive end-expiratory pressure (PEEP) increases arterial carbon dioxide tension and alveolar dead space by reducing alveolar capillary perfusion. The two likely mechanisms by which PEEP reduces alveolar capillary perfusion are reduction of cardiac output or compression of pulmonary capillaries within interalveolar septa, or both mechanisms. This study attempts to quantitate the impact of each of these mechanisms on alveolar capillary perfusion in anesthetized dogs by restoring cardiac output to baseline values with dextran 70 infusion after application of 15 cm H2O PEEP.

Detection of activated double-stranded RNA-dependent protein kinase in 3T3-F442A cells.

We have previously reported that cultured mouse 3T3-F442A cells exhibit a transient, double-stranded RNA (dsRNA)-dependent phosphorylation of the dsRNA-dependent eIF-2 alpha kinase (eIF-2 alpha, alpha-subunit of the eukaryotic initiation factor 2) (dsI). When dsI is activated by low levels of dsRNA, it is a potent inhibitor of protein synthesis. The transient expression of dsI is due to an autocrine effect of interferon at specific stages of growth and differentiation, and it may represent a mechanism for regulating cell growth and differentiation in 3T3-F442A cells.

Effect of endurance training on leucine metabolism in perfused rat skeletal muscle.

An isolated single rat hindlimb muscle preparation was used to examine the influence of exercise training on leucine metabolism during steady-state conditions at rest and during isometric contractions. Treadmill training increased the activity of citrate synthase in the hindlimb muscle by 40-45%. Leucine oxidation, measured as the rate of alpha-decarboxylation, was not different between trained (2.

Leucine metabolism in perfused rat skeletal muscle during contractions.

An isolated single rat hindlimb muscle preparation was used to examine leucine metabolism during steady-state conditions as a function of metabolic rate (VO2) and leucine concentration. The rates of muscle leucine uptake and leucine oxidation (measured as alpha-decarboxylation) were dependent on leucine delivery. At a physiological leucine concentration (0.

Carbon dioxide laser laparoscopy performed with a flexible fiber in humans.

A flexible carbon dioxide laser fiber delivery system was used in conjunction with the laparoscope to treat 12 women. The 77 by 2 mm hollow fiber could subtend an arc of 90 degrees without significant loss of power or unfavorably affecting the delivery mode. As many as 20 W of power was transmitted through the fiber; however, carbon dioxide gas flow rates as high as 2000 cc/min reduced power by approximately 25%.

Positive interaction between insulin and phorbol esters on the regulation of a specific messenger ribonucleic acid in rat hepatoma cells.

With Northern blot analysis, we demonstrate that phorbol 12-myristate 13-acetate (PMA) stimulated P-33 messenger RNA (mRNA)-accumulation in rat hepatoma cells in a time- and concentration-dependent manner similar to insulin and plant lectins. No effect of PMA on P-33 mRNA half-life was detected when mRNA synthesis was inhibited with either actinomycin D or 5.6-dichloro-1-beta-D-ribofuranosyl benzimidazole.