Transfer of streptomycin biosynthesis gene clusters within streptomycetes isolated from soil

Streptomyces strains isolated from soil were found to possess various numbers of genes from the streptomycin biosynthesis cluster. The strains missing genes from the cluster also lacked the ability to produce streptomycin. Two of the isolates which contain only part of the cluster are apparently recipients of a gene transfer event. The implications for the role of gene transfer in antibiotic evolution are discussed.     

Spontaneous perimesencephalic subarachnoid hemorrhage (PMH). A disease category with good prognosis?

Perimesencephalic subarachnoidal haemorrhage (PMH) is characterized by a typical blood distribution pattern in the basal cysterns in the CAT, missing evidence of an aneurysm in the panangiogram, a mild clinical course and a very positive prognosis. Between 1990 and 1995, 108 inpatients with non-traumatic subarachnoidal haemorrhage were treated in our clinic. Within this group 14 patients (13%) were identified retrospectively with a perimesencephalic haemorrhage distribution pattern in the CAT and a negative panangiogram. These patients experienced a mild clinical course with excellent outcome without rebleeding during the observation period of 2 to 50 months. All patients were fully able to work, and only two patients complained of frequent headaches. The mild clinical course, the negative panangiogram as well as the extremely positive outcome confirm the hypothesis of of a benign subgroup of non-traumatic subarachnoidal haemorrhages.     

Neutralization of conservative charged transmembrane residues in the Na+/glucose cotransporter SGLT1

Our goal was to identify pairs of charged residues in the membrane domains of the Na+/glucose cotransporter (SGLT1) that form salt bridges, to obtain information about packing of the transmembrane helices. The strategy was to neutralize Glu225, Asp273, Asp294, and Lys321 in helices 6-8, express the mutants in oocytes, measure [14C]-alphaMDG uptake, and then attempt to find second-site mutations of opposite charge that restored function. alphaMDG uptake by E225A was identical to that by SGLT1, whereas transport was reduced by over 90% for D273A, D294A, and K321A and was not restored in the double mutants D273A/K321A or D294A/K321A. This suggested that K321 did not form salt bridges with D273 or D294 and that E225 was not involved in salt-bridging. Neutralization of K321 dramatically changed the Na+ uniport and Na+/glucose cotransport kinetics. The maximum rate of uniport in K321A increased 3-5-fold with a decrease in the apparent affinity for Na+ (70 vs 3 mM) and no change in apparent H+ affinity (0.5 microM). The change in Na+ affinity caused a +50 mV shift in the charge/voltage (Q/V) and relaxation time constant (tau)/voltage curves in the presteady-state kinetics. The presteady-state kinetics in H+ remained unchanged. The lower Na+ affinity resulted also in a 200-fold increase in the apparent K0.5 for alphaMDG and phlorizin. Replacements of K321 with alanine, valine, glutamine, arginine, or glutamic acid residues changed the steady-state kinetics in a similar way. Therefore, we suggest that K321 determines, directly or indirectly, (i) the rate and selectivity of SGLT1 uniport activity and (ii) the apparent affinities of SGLT1 for Na+, and indirectly sugar in the cotransport mode.     

Successful allogeneic bone marrow transplantation in selected patients over 50 years of age--a single institution's experience

As allogeneic bone marrow transplantation (BMT) is a procedure with a higher risk of morbidity and mortality in older patients, many institutions place a limit of 50 to 55 years for allogeneic BMT. Consequently, older patients may not be offered potentially curative treatment for otherwise poor prognosis diseases such as AML or myelodysplastic syndrome. We compared the outcome of 59 patients aged over 50, 124 aged 40-50, and 253 aged 18-39 years who underwent allogeneic BMT in our institution between August 1987 and April 1996. Our results show little influence of age on outcome when comparing patients over 50 years with patients 40-50 years. Apart from an initial higher transplant mortality rate, overall survival was not significantly different between the three age groups. The 1-year and 2-year overall survival rates were 57% and 48%, 57% and 48%, and 62% and 58% for the >50 years, 40-50 years, and <40 years patients, respectively. The incidence of GVHD was also comparable. We conclude that allogeneic BMT can be performed in selected patients over the age of 50 years with acceptable morbidity and mortality and that older patients should not be denied this treatment based on age alone.     

Organization of care for tuberculosis children who had contact with maternal hospital worker suffering from bacillar tuberculosis

While contacting a patient with bacillar tuberculosis, neonates and their mother are at risk for the disease, which makes it necessary to make up a programme that involves emergency antituberculosis measures. Among them primary specific drug therapy in all children in contacts, which may prevent tuberculosis in them, is highly effective.