The lymphocyte restimulation system: Evaluation by intra-HLA-D group priming

Homozygous typing cells (HTC) were primed, using responding and stimulating lymphocytes of the same HLA-D groups. These intra-HLA-D group primings showed strong specific responses. Restimulation by HLA-D heterozygous and homozygous cell panels showed no correlation between the restimulating determinant and HLA-D. On the other hand, an unrelated individual, not carrying Dw4 and primed to Dw4 HTC, is restimulated by three of four Dw4-HTC. Thus, one non-HLA-D-associated restimulating determinant and another HLA-D-associated determinant could be identified. The differences among the four Dw4 HTC recognized in secondary MLC could reflect either recognition of separate gene products or recognition of separate determinants on the same gene product.     

Hormone-dependent processing of the avian progesterone receptor

Avian progesterone receptor exists as two forms, A and B, with molecular weights of 79,000 and 110,000 daltons, respectively. The origin and significance of these two forms is an area of active investigation and debate. Monoclonal antibodies produced against these two forms were used to examine receptor stability in cytosol and changes in the receptor forms induced by hormone binding. The lability of hormone binding at elevated temperatures is well documented. Analysis by Western blotting showed the receptor was stable in freshly prepared oviduct cytosol for 2 hr at 37°C, while hormone binding was lost within 30 min. However, loss of receptor through degradation was seen when cytosol was prepared from frozen tissue or when homogenization was excessive. Progesterone was injected into diethylstilbestrol-stimulated chicks to examine, in vivo, effects of hormone treatment on receptor forms in the cytosol and nuclear fractions. Progesterone treatment caused a time- and dose-dependent conversion of the A receptor to a form (A′) with a slower electrophoretic mobility. The cytosolic progesterone receptor was divided equally between the B and A forms, while the nuclear receptor was predominantly A′. The amount of nuclear receptor was consistently less than cytosolic receptor. Receptor phosphorylation was analyzed by incubating tissue minces with [³²P]orthophosphate with or without progesterone followed by immune isolation of receptor forms. Progesterone treatment caused a time-dependent increase in cytosol receptor phosphorylation which was evident after 5 min of treatment. This phosphorylation was observed with both the A and B receptor forms. The results indicate that receptor phosphorylation is a very early event during progesterone action.     

Involvement of protease in L-glutamine control of nucleic acid and polyphosphate metabolism in cells transformed by 9,10-dimethyl-1,2-benzanthracene, SV40 and H-ras oncogene

Mammalian cells transformed with either 9,10-dimethyl-1,2-benzanthracene, SV40 or H-ras oncogene dramatically changed their ability to synthesize DNA and RNA and metabolize polyphosphate when L-glutamine was withdrawn from the growth medium or when heat shocked (growth at 42 degrees C). Untransformed, DNA and RNA synthesis decreased by 50-80% when glutamine was withdrawn, but polyphosphate accumulated whether or not glutamine was supplied. Heat shock did not alter this response. Transformed isogenic cells responded differently; at 37 degrees C, they decreased their synthesis of DNA and RNA if starved for glutamine, whereas at 42 degrees C, synthesis was optimal without glutamine. Transformed cells accumulated polyphosphate at 37 degrees C when starved for glutamine, but at 42 degrees C, no polyphosphate accumulated. This apparent non-dependence on glutamine by transformed cells when heat shocked was found to be due to the production of glutamine from serum proteins through induction of a protease(s).     

A three dimensional serial reconstruction of neuronal distributions in the hypostome of a Hydra

The numbers, types, and distributions of neurons in a hypostome of Hydra littoralis were determined from electron micrographs of serial (0.25 μm thick) sections. In 1,080 serial sections examined we found 75 sensory cells and 949 centrally located ganglion cells. More than 96% of the 1,024 neurons identified had a single cilium. Sensory cells were most numerous near the apex of the hypostome. Proceeding away from the apex, they steadily decreased in numbers; at 120 μm they were no longer observed. Ganglion cells were bimodally distributed; some were associated with sensory cells at the apex, but most were found at the sites of tentacle origin. We observed, throughout the hypostome, a total of 64 neuronal clusters (three or more contiguous neurons), with an average of five and a maximum of 11 neurons in a cluster. Clusters were distributed similarly to ganglion cells: an initial concentration of clusters near the apex; the majority at the hypostometentacle junctions. Each neuron identified was traced through succeeding sections in which it was observed. We used a three coordinate system to create a three-dimensional reconstruction of the neuronal locations in the hypostome. Although the functional significance of the neuronal distributions we observed is unknown, we suggest that neurons at the apex of the hypostome transduce sensory information involved in feeding behavior. The neuronal concentrations at sites of tentacle origin may be responsible for initiating Contraction Burst Pulses associated with rhythmic behavioral patterns of Hydra or coordinating tentacle movements involved in prey capture, ingestion or locomotion.     

The recycling of a secretory granule membrane protein

We have used N-hydroxysuccinimido-d-biotin as a reagent for labeling proteins exposed at the surface of cultured bovine adrenal chromaffin cells during Ba2+-stimulated secretion. A specific secretory granule membrane constituent, dopamine-beta-hydroxylase (DBH), has been investigated using immunoprecipitation followed by electrophoresis. Within 30 min of stimulation, exposed DBH had been cleared from the cell surface. Nevertheless, quantitation of labeled DBH using [125I] streptavidin suggested that it remained undegraded over a period of 24 h, a time during which secretory granule stores of catecholamines were being replenished. Subcellular fractionation of the cultured cells suggested that, after 3 or 4 h, the biotinylated DBH, which was still membrane-bound, was located in particulate material that also contained cytochrome b561, another major secretory granule membrane component.     

The uptake of liposome-entraped 125I-labelled poly(vinylpyrrolidone) by rat jejunum in vitro

The uptake of free and liposome-entrapped ¹²⁵I-labelled poly(vinylpyrrolidone) was measured in an intestinal sac preparation from adult rats. An an equal concentration of ¹²⁵I-labelled poly(vinylpyrrolidone), the rate of uptake of the liposome-entrapped material was four times that of the free macromolecule.     

Rock-Climbing Injuries in Yosemite National Park

This study was presented in part at the annual meeting of the Wilderness Medical Society at Aspen, Colorado, in August 1986 and at “Mountain Medicine 1987,” Leavenworth, Washington, in November 1987.We questioned 220 injured rock climbers or their partners seen consecutively at the Yosemite (California) Medical Clinic over 3 ½ years regarding details of their accidents. Injury type and location were extracted from medical records and severity quantified. The National Park Service rescued 27% of the climbers. Injured climbers were characteristically male (88%) and experienced (mean 5.9 years) and typically fell while leading climbs (66%). Among 451 injuries, 50% were to the skin or subcutaneous tissues, while 28% involved the lower extremity and were predominantly fractures. In terms of each climber''s most severe injury (n = 220), 45% involved the lower extremities (30% from the ankle alone). Head injury or hypothermia caused 12 of 13 fatalities, showing the lowest case-fatality rate reported to date among injured climbers (6%). Rescue personnel successfully managed airways in victims of head injuries, anticipated and treated complications of hypothermia, and stabilized fractures. Victims requiring immediate extensive surgical intervention or blood transfusion usually died before rescue could be effected.