Efficient multi-keV underdense laser-produced plasma radiators.

Novel, efficient x-ray sources have been created by supersonically heating a large volume of Xe gas. A laser-induced bleaching wave quickly ionizes the high- Z gas, and the resulting plasma emits x rays. This method significantly improves the production of hard x rays because less energy is lost to kinetic energy and sub-keV x rays. The conversion efficiency of laser energy into L-shell radiation between 4-7 keV is measured at approximately 10%, an order of magnitude higher than efficiencies measured from solid disk targets. This higher flux enables material testing and backlighting in new regimes and scales well to future high-powered lasers.

Adherence assay of 51chromium-labeled human polymorphonuclear leukocyte using glass beads.

There is a need for a reliable and relatively simple assay of in vitro adherence capacity. We have modified a previously described method of adherence of 51Cr-labeled PMN to glass beads and developed an assay which should be of value in both the clinical and research areas. The assay measures PMN adherence in the non-stimulated state and also following stimulation with phorbol myristate acetate (PMA) or endotoxin-activated plasma (EAP) using as few as 0.25 X 10(6) PMN. The differences observed between the adherence of stimulated and non-stimulated PMN were highly significant.

Ontogeny of the immune system: fetal lamb as a model.

We examined adult sheep lymphocytes for the following surface markers: Surface membrane immunoglobulin, antigen identified by anti-sheep thymocyte globulin and complement receptors. We quantitated sheep peripheral blood mononuclear leukocyte proliferative responses to mitogens and alloantigens, and demonstrated a neutrophil-directed chemotactic factor (N-LDCF) liberated by mitogen-stimulated sheep mononuclear cells. A comparison of adult and fetal sheep from 120-150 d of gestation demonstrated that 1) fetal sheep had adult proportions of surface membrane Ig+ and T+ lymphocytes but a significant decrease in FcIgG receptor+ lymphocytes, 2) proliferative responses of fetal sheep blood mononuclear cells to mitogens and alloantigens were comparable to adult responses, and 3) fetal mononuclear leukocytes failed to produce the lymphokine, N-LDCF, in response to mitogen stimulation.

Thrombogenicity and the interaction of proteins, platelets and white cells.

Radioactive labeled protein and platelet studies suggest that an ideal vascular surface absorbs albumin and prevents platelet adherence and aggregation. This study examines the interaction of serum and plasma proteins, white cells, and platelets in the thrombotic response to small internal diameter vascular prostheses. Thirty-seven replamineform silicone rubber vascular prostheses, 4 mm internal diameter and 6 cm length, had 5% aspirin and 5% theophylline by weight dispersed in a luminal coating (D); the remaining 37 control (C) prostheses had an identical silicone rubber coating without drugs. Scanning electron and darkfield microscopy confirmed similar surface topography in C and D grafts. One C and one D graft were studied in parallel using a modified canine arteriovenous fistula. Consistently, D prosthesis had increased bleeding through the graft wall. The 7 serum and 8 plasma experiments demonstrated greater accumulation on the D prostheses, the greatest deposition occurring within the first 30 minutes. In 8 platelet experiments, D grafts accumulated more radioactivity at both the 5 and 30 minute intervals. Six mononuclear and 8 PMN experiments had less accumulation on the D grafts at 15 minutes and no consistent difference at 60 minutes. Elution of C and D Grafts demonstrated significant drug levels in only the D grafts at the beginning of the experiments and after 15 minutes of exposure of blood. We conclude: (1) aspirin and theophylline have an effect on the initial interaction of plasma proteins, platelets and white cells in the thrombogenic response, (2) the effect diminishes as time released drug levels decrease.

Isolation of ovine lymphocytes, granulocytes, and monocytes by counterflow centrifugation elutriation.

A simple, brief 1-step counterflow centrifugation elutriation technique is described for the recovery of highly purified populations of lymphocytes and granulocytes from adult and fetal ovine peripheral blood. Monocytes are obtained as an enriched population. Lymphocyte and granulocyte recoveries average 80%, higher than with routine gradient centrifugation procedures. In this described technique, inexpensive medium is used, and it is completed in about 90 minutes. The individual blood cellular populations, when tested appropriately, demonstrated normal functional responses.