Platelet dosing.

Many patients with thrombocytopenia require transfusion of platelet concentrates, and numerous factors may influence the observed response to transfusion. One factor gaining growing recognition in recent years is the consideration of the dose of platelets to administer. Review of the available data regarding the effect of platelet dose on transfusion outcome is presented in this summary, with attention to those situations that seem to require higher platelet doses. Appropriate dosing may not only improve the immediate response to transfusion, but also lead to a decrease in further platelet transfusion requirements. Recommendations supported by actual clinical data are outlined, but controlled studies are needed to determine optimum platelet doses for many common clinical situations.     

Preemptive Retransplantation for BK Virus Nephropathy: Successful Outcome Despite Active Viremia

BK virus nephropathy (BKVN) is now recognized as a major cause of renal allograft loss. Recent reports suggest that retransplantation in patients with graft loss due to BKVN is safe after return to dialysis. Since early transplantation is associated with improved outcomes, it would be advantageous if this procedure could be performed prior to ultimate graft loss. However, little data are available regarding the safety of this approach during active viremia. In this report, we describe successful preemptive retransplantation with simultaneous allograft nephrectomy in two patients with active BKVN and viremia at the time of surgery. With 21- and 12-month follow-up, respectively, both patients have stable allograft function and no evidence for active viral replication. We conclude that preemptive retransplantation can be considered in patients with failing allografts due to BKVN.     

An analysis of the action of an analogue of almitrine bismesylate in the rat model of hypoxic lung disease.

Chronically hypoxic (CH) and normoxic control rats were used to assess the action of S9581, a water-soluble analogue of almitrine bismesylate. S9581 increased ventilation (Ve) by 34% in control and 20% in CH rats. During acute hypoxia Ve was raised and S9581 caused a further increase of 20% in both groups. Low doses of S9581 and almitrine enhanced the hypoxic ventilatory response in CH rats while high doses depressed it in both groups. Effects of S9581 on the pulmonary circulation were assessed in the isolated perfused lung of rats. As with almitrine a complex relationship of dose-dependent vasoconstriction and dilatation was revealed. In low doses, S9581 enhanced the hypoxic pulmonary vasoconstrictor response to 2% O2 whilst this was attenuated by high doses in both control and CH rats. S9581 seemed to act like almitrine bismesylate on both the ventilation (peripheral chemoreceptor) and the pulmonary circulation. For studying almitrine-like activity the water solubility of S9581 provides considerable advantages for the researcher.     

Estimating neuron dendritic length in 3D from total vertical projections and from vertical slices

The recently developed method of total vertical projections is illustrated to estimate the total dendritic length of a human Substantia Nigra neuron. Next, the length of the different orders of dendritic branches, and the mean segment length for each order - commonly regarded as important parameters in neuron physiology - are also estimated. Finally, it is shown how to estimate the mean dendritic length in a population of neurons from vertical slices of arbitrary and unknown thickness. Being unbiased and highly efficient, the proposed methods offer interesting alternatives to current procedures used for the metric analysis of neuron arborizations.     

Intracerebroventricular LHRH relieves behavioral deficits due to vomeronasal organ removal

Contact between the sexes in many species is known to produce hormonal changes in the male [increases in serum luteinizing hormone (LH) and/or testosterone] that can be interpreted as due to an intracerebral release of LH-releasing hormone (LHRH). In some circumstances, these hormonal changes appear to depend on an intact vomeronasal sensory system. Exogenous LHRH is also known to facilitate mating behavior in several species. We show here that LHRH delivered into the cerebral ventricles can restore some mating behavior lost when the vomeronasal organs are removed from sexually inexperienced male hamsters. The results are consistent with our working hypothesis that intracerebral LHRH release is an intermediate in the facilitation of mating behavior by vomeronasal sensory input.     

Second births among teenage mothers: program results and statistical methods

This paper uses survival analysis to examine three large-scale, multi-site, randomized, controlled programs that attempted to prevent or delay second births to teenagers. Statistically significant differences in the hypothesized direction were found between the intervention and the control groups in the Elmira and Memphis Home Visitation sites. No statistically significant differences in the hypothesized direction were found in the Teen Parent Welfare Demonstration overall or in any of its three sites or in all New Chance sites combined. Delaying second pregnancies among teenagers requires intensive efforts. Survival analysis is a more accurate and useful way of presenting program results than simple analysis of the proportion of women with a second birth.     

A patient with Werner's syndrome and osteosarcoma presenting as scleroderma.

Werner's syndrome (WS) is often mistaken for scleroderma. We describe a patient with WS who presented with an enlarging, painful mass of the right knee that proved to be a juxtaarticular osteosarcoma of the distal femur. Recognition of WS and prompt investigation of any painful, enlarging masses to exclude sarcomatous degeneration will benefit these patients.     

Regulation of autoimmune response

Recent work on such apparently disparate fields as T-cell receptor peptide-induced regulation, superantigens, antigen-induced tolerance, models of peripheral tolerance, apoptosis, and T-cell receptor antagonists demonstrates a similarity in immune response from a regulatory perspective. In many systems, a ‘tolerance’ pathway is observed, characterized broadly as an initial disturbance in the immune system, with a resulting predominance of effector cells, followed by a homeostatic response (often requiring CD8⁺ cells) which leads the effector population into T-cell receptor downregulation, T-cell inactivation, anergy and, often, eventual apoptotic death. In the regulated immune response, mixed populations of anergized and apoptosing T cells can be found. In some cases, anergy appears to lead to death while, in other instances, cells revert to a functional state. This review focuses on recent papers examining each of these topics in an attempt to obtain a preliminary, integrated picture of immune regulation in autoimmune diseases.