Maintenance of hemopoietic stem cells in diffusion chamber cultures

When murine bone marrow cells are cultured in DC's in irradiated host mice, there is an initial phase of rapid white cell growth followed by prolonged maintenance of steady-state granulopoiesis. This study examined the role of hemopoietic stem cells in this culture system. During the initial growth phase there was a rapid increase in both pluripotential stem cells, CFU-S, and commmitted white cell precursors, CFU-C. The increase in CFU-C was larger, occurred more rapidly, and was biphasic in nature. After day 7 and until at least day 16, the numbers of CUF-S, CFU-C and total white cells were all maintained at relatively constant plateau levels which were typically well below the maximal capacity of the culture system. During the plateau phase the number of CFU-S was slightly greater than the number initially placed in culture, whereas CFU-C had increased by a factor of 2.3 and total white cells by a factor of 10. This appears to reflect a system of growth amplification, with preferential differentiation of CFU-S into CFU-C and thence into the pathway of white cell development. The plateau phase of culture has received very little attention but appears to represent a model, in a closed culture system, of finely regulated granulopoiesis, with an equilibrium between constant numbers of hemopoietic stem cells and their differentiating white cell progeny.     

The peripheral neuromotor apparatus of patients with tick-borne neuroborreliosis (Lyme disease)

Electroneuromyography and electromyography were performed in 48 and 102 patients, respectively, with Lyme disease-induced algic and amyotrophic syndromes. Electromyographic and clinical findings in the regions of the tick suction correlated. Multiple lesions of the nervous system may be considered as meningoencephalomyeloradiculoneuropathy as well as subclinical multiple mononeuropathy. Pronounced changes in the nerve potential against minimal shifts in peripheral nervous conduction reflect infectious-toxic nature of the condition.     

Mortality and morbidity from malaria after stopping malaria chemoprophylaxis

Gambian children who had received malaria chemoprophylaxis for a variable period of time during their first 5 years of life were followed to determine whether they experienced a rebound in mortality or in morbidity from malaria during the period after chemoprophylaxis was stopped. The risk of dying between the ages of 5 years, when chemoprophylaxis was stopped, and 10 years was no higher among children who had received chemoprophylaxis with Maloprim (pyrimethamine plus dapsone) for some period during their first 5 years of life than among children who had received placebo (21 vs. 24 deaths) and the beneficial effect of chemoprophylaxis on mortality observed during the first 5 years of life was sustained. The incidence of clinical attacks of malaria during the year after medication was stopped was significantly higher among children who had previously received Maloprim for several years than among children who had previously received placebo. However, at the end of this year, there was no significant difference in spleen rate, parasite rate or packed cell volume between the 2 groups of children. Thus, stopping chemoprophylaxis after a period of several years increased the risk of clinical malaria but did not result in a rebound in mortality in Gambian children. However, the number of deaths recorded was small, so a modest effect on mortality cannot be excluded.