The fate of the open canalicular system in surface and suspension- activated platelets

We have examined the movement of fibrinogen-gold (fgn-Au) complexes in platelets activated in suspension and by surface contact. Fgn-Au probes did not react with resting cells but were bound to the external membrane of platelets in suspension 5 seconds after addition of 1 U/mL of thrombin. At intervals over a period of 5 to 20 minutes, fgn-Au probes moved from the cell surface to peripheral and then deep channels of the open canalicular system (OCS). When platelets were surface activated by exposure to carbon-stabilized, formvar-coated grids for 5 to 20 minutes and then exposed to fgn-Au complexes for 5 minutes, probes were also observed in the OCS. At 5 minutes, over 40% of the platelets had concentrated fgn-Au in their OCS. Results after 10 minutes revealed 25% with gold-filled channels, 16% after 15 minutes, and 5% after 20 minutes. The decrease in frequency of OCS staining correlated with the increasing frequency of spread platelets, suggesting that tension produced by spreading may cause collapse of the OCS or that the OCS may evaginate onto the platelet during spreading. To evaluate the latter hypothesis, platelets were initially exposed to grids for 5 minutes and then incubated with fgn-Au for intervals of 5 to 20 minutes. The frequency of platelets with fgn-Au concentrated in the OCS was greatest at 5 minutes (44%) and decreased at the same rate as the frequency of spread platelets increased. Only 14.7% of the cells contained fgn-Au in the OCS after 20 minutes. These were primarily dendritic in form, while fully spread platelets rarely contained an OCS filled with the probe. The study indicates that fgn-Au particles are cleared to channels of the OCS independent of the mechanism of platelet activation. Fgn-Au that has been concentrated in the OCS at early stages of surface activation can be externalized during platelet spreading but remain internalized in suspension-activated cells. The OCS represents a membrane reservoir that can be evaginated onto the platelet surface during interaction with surfaces.     

Psychological challenges of bioterror: containing contagion

In this article, we have introduced the concept of shielding as a public mental health intervention. Shielding addresses the core elements of bioterrorism when we consider that bioterrorism is best understood as terrorism, i.e., psychological warefare, which merely employs biologic agents, not to kill, but to terrorize. It is, therefore, to some degree dependent upon widespread contagion. Shielding is not a panacea. It is one aspect of an overall response plan. Nevertheless, it represents a potentially useful "antidote" for the bioterrorist assault. Perhaps most significant among its putative mechanisms of action appears to be controlling contagion, both physical and psychological. In the final analysis, in the wake of a terrorist attack, physicians can physically immunize and treat those who require such attention. Engineers can reconstruct buildings and roads. But who rebuilds the essence of humanity which has been violently ripped away from those who suffered the terrorist attack? How do we reconstruct a belief in justice and safety in the wake of a mass terrorist attack? Without attention to mental health, i.e., the "psychological side of terrorism," we run the risk of rebuilding a nation without a spirit, without a vitality, without a sense of humanity.     

Emphysema in the renal allograft

Two diabetic patients in whom emphysematous pyelonephritis developed after renal transplantation are described. Clinical recognition of this unusual and serious infection is masked by the effects of immunosuppression. Abdominal radiographic, ultrasound, and computed tomography findings are discussed. The clinical presentation includes urinary tract infection, sepsis, and acute tubular malfunction of the allograft in insulin-dependent diabetics.     

Vitamin supplementation of HIV-infected women improves postnatal child growth

BACKGROUND: Linear growth retardation and wasting are common in children born to HIV-infected women. Inexpensive interventions that could improve the postnatal growth pattern of such children are needed. OBJECTIVE: The objective was to examine the effect of supplementing HIV-infected women with multivitamins or vitamin A and beta-carotene, during and after pregnancy, on the growth of their children during the first 2 y of life. DESIGN: We conducted a randomized placebo-controlled trial in 886 mother-infant pairs in Tanzania. At the first prenatal visit, HIV-infected women were randomly assigned to 1 of 4 daily oral regimens in a 2 x 2 factorial fashion: multivitamins (MV: thiamine, riboflavin, vitamin B-6, niacin, vitamin B-12, vitamin C, vitamin E, and folic acid), preformed vitamin A + beta-carotene (VA/BC), MV including VA/BC, or placebo. Supplementation continued during the first 2 y postpartum and thereafter. Children were weighed and measured monthly, and all received vitamin A supplements after 6 mo of age per the standard of care. RESULTS: Multivitamins had a significant positive effect on attained weight (459 g; 95% CI: 35, 882; P = 0.03) and on weight-for-age (0.42; 95% CI: 0.07, 0.77; P = 0.02) and weight-for-length (0.38; 95% CI: 0.07, 0.68; P = 0.01) z scores at 24 mo. VA/BC seemed to reduce the benefits of MV on these outcomes. No significant effects were observed on length, midupper arm circumference, or head circumference. CONCLUSION: Supplementation of HIV-infected women with multivitamins (vitamin B complex, vitamin C, and vitamin E) during pregnancy and lactation is an effective intervention for improving ponderal growth in children.     

Lethal predators: psychopathic, sadistic, and sane

The violent criminals defined in this article are a small, exceptionally dangerous group of offenders designated by the authors as "lethal predators." They have a history of sexual predation, have killed at least once, and are mentally abnormal but legally sane. They are highly likely to keep killing as long as they are free. Laws permitting civil commitment of dangerous and mentally abnormal sexual predators after they have completed criminal prison sentences have been upheld by the U.S. Supreme Court. Such laws can provide a legal means of keeping these highly dangerous killers confined so they cannot kill again.     

Influence of caloric restriction on the development of atherosclerosis in nonhuman primates: progress to date

Caloric restriction (CR) has been observed to retard aging processes and extend the maximum life span in rodents. In an effort to evaluate the effect of this nutritional intervention on physiologic variables in higher species, several nonhuman primate trials are ongoing. In particular, a study evaluating the independent effect of CR on the extent of atherosclerosis was initiated in 1993 in 32 adult cynomolgus monkeys. Therefore, the trial was designed to achieve identical cholesterol intake after animals were randomized to a control group or a calorie-restricted group (30% reduction from baseline caloric intake). The animals were routinely evaluated for glycated proteins, plasma insulin and glucose levels, insulin sensitivity, and specific measures for abdominal fat distribution by CT scans over a 4-year interval. The results from 4 years of intervention demonstrate that CR improves cardiovascular risk factors (such as visceral fat accumulation) and improves insulin sensitivity. In contrast to other primate studies with normolipidemic animals, CR had no independent effects on plasma lipid levels and composition in the presence of equivalent amounts of dietary cholesterol intake. Preliminary analysis of atherosclerotic lesion extent in the abdominal aorta has failed to demonstrate differences between control animals and CR animals. Follow- up studies are being conducted to determine the effect of CR on atherosclerosis extent in coronary and carotid arteries.