Bone marrow innervation regulates cellular retention in the murine haemopoietic system

An anatomical analysis of the innervation of murine femora revealed intimate association of haemopoietic and stromal cells with nerve fibres. The mechanical denervation of these femora resulted in significant mobilization of cells into the peripheral blood within 24h. There was a decrease in femoral cellularity and analysis of the type of cells mobilized also revealed that there was an increase in progenitor cells in the peripheral blood. In non-splenectomized mice these progenitor cells were quickly cleared from the circulation. Chemical sympathectomy of mice with 6-hydroxydopamine resulted in decreased bone marrow cellularity without a change in bone marrow or peripheral blood progenitor cell numbers, nor the sustained rise in peripheral leucocytes observed with whole nerve denervation. These observations argue for selective control of mobilization by the nervous system and also indicate possible control of proliferation within the bone marrow. We conclude that the innervation has an important role in the maintenance of the blood-marrow interface, control of peripheral blood cell numbers, and mobilization of colony forming cells into the periphery.     

Vitamin supplementation therapy in the elderly

Vitamin supplementation in large dosages is increasingly common in the older population. Often, such supplementation is used in an attempt to improve an individual's health status. There have been claims that the effects of vitamins halt the normal aging process or prevent and cure disease. However, several recent studies have failed to demonstrate the efficacy of vitamin supplementation in preventing several types of cancer. In moderate dosages, supplementation with vitamin E (tocopherols) shows promise as a lipid antioxidant, and may reduce the risk of coronary heart disease. However, before vitamin E becomes an accepted medical therapy, further long term studies must be undertaken to examine the safety and efficacy of such therapy. An adequate intake of vitamins should be ensured by adherence to a well balanced diet. However, the elderly are prone to circumstances that may prevent them from eating a balanced diet. In addition, there are several age-related medical conditions that may predispose individuals to dietary and vitamin deficiencies. To prevent vitamin deficiency diseases and their associated morbidity, modest vitamin supplementation may be necessary. However, supplementation should be reserved for individuals with documented deficiency or who are at risk of developing such deficiencies, especially those who are homebound or institutionalised. Vitamins taken in large dosages should be considered as drugs. These medicines, which are obtainable over-the-counter, should be carefully regulated to prevent toxicity.     

The scourge of HIV-related tuberculosis: a cohort study in a district general hospital in Malawi

Malawi is similar to a number of other African countries in having an escalating, HIV-related, tuberculosis (TB) epidemic. A prospective study was carried out to determine the pattern of disease and HIV serostatus in unselected, adult, TB patients consecutively admitted to a large, district general hospital in Zomba (in the Southern region of Malawi). Clinical details were obtained, from the district TB register, for the 714, adult TB patients, aged > or = 15 years, who were registered with the district TB officer between 1 July and 31 December in 1995. Patients were counselled, and offered HIV testing using an ELISA and particle agglutination test. Concordant HIV-test results were available for 686 (96%) of the subjects: 547 (80%) of these were HIV-seropositive and 139 seronegative. The HIV-positive patients were significantly younger than the HIV-negative patients and significantly more HIV-positive patients were males (P < 0.05 for each). The proportions of HIV-positive subjects who were new patients, had been previously treated for TB, had pulmonary TB (PTB), had smear-positive PTB or had different types of extrapulmonary TB were similar to those of the HIV-negative. A high percentage of an unselected cohort of adult TB patients admitted to a district, general hospital in Malawi, particularly of the younger age groups was therefore HIV-positive. The pattern of disease was uninfluenced by the HIV serostatus. The large number of cases registered emphasises the severity of the current epidemic of TB in Malawi and its impact upon young adults.     

Comparison of a novel microaerobic system with three other gas-generating systems for the recovery of Campylobacter species from human faecal samples

Three commercial gas-generating systems--CampyGen (Oxoid, UK), Oxoid BR56 (Oxoid, UK), and CampyPak Plus (Becton Dickinson, USA)--and the evacuation replacement technique were compared for the recovery of Campylobacter spp. from 500 human faecal samples collected from patients with gastroenteritis. Four hundred fifty faecal samples were tested upon receipt in the laboratory. Fifty faecal samples that had been previously found to be positive for Campylobacter spp. were tested retrospectively; these had been stored at 4 degrees C for more than 48 h. A total of 41 (9.1%) of the fresh faecal samples and 41 of 50 (82%) of the stored faecal samples were positive for thermophilic campylobacters. The CampyGen, the Oxoid BR56, the CampyPak Plus, and the evacuation replacement system detected Campylobacter spp. in 40 (97.6%), 39 (95.1%), 41 (100%), and 41 (100%) of the positive fresh faecal samples and in 37 (90.2%), 40 (97.6%), 39 (95.1%), and 40 (97.6%) of the stored samples, respectively. There was no statistical difference in performance of any of the four gas systems used (p = 0.98; chi-square test). Eighty-six percent of the isolates were Campylobacter jejuni and 14% were Campylobacter coli. Biotyping and phage typing of the isolates demonstrated that they were of a diverse range of subtypes. This study demonstrates that thermophilic campylobacters can be isolated from human diarrhoeal faecal samples using any of the four microaerobic-atmosphere-generating systems.     

Response to cognitive-behavioral therapy in depression: effects of pretreatment cognitive dysfunction and life stress

Response to cognitive-behavioral therapy (CBT) for depression is variable and the factors that account for differences in response are not yet well established. Level of cognitive dysfunction and the occurrence of negative life stress have been theorized as patient variables, which may account for differences in response to CBT. The relationship between response to CBT and the interaction of cognitive dysfunction with negative life events was examined in a sample of 53 depressed outpatients. Overall, there was little support for the prediction of a difference in acute outcome between patients with or without pretreatment cognitive dysfunction and negative stressors.     

In vitro selection of RNA lectins: using combinatorial chemistry to interpret ribozyme evolution

BACKGROUND: It has been hypothesized that the fact that both ribosomal RNA and the group I intron can bind to aminoglycoside antibiotics implies that these RNAs are evolutionarily related. This hypothesis requires the assumption that there are relatively few ways for RNA molecules to form aminoglycoside-binding sites. RESULTS: We have used in vitro selection to determine the diversity of aminoglycoside-binding sites that can be formed by RNA molecules. We have generated RNA 'lectins' that can bind aminoglycosides tightly and specifically. Sequence analysis indicates that there are many different ways to form tight and specific aminoglycoside binding sites. These artificially selected binding sites are functionally similar to those that have arisen from natural selection. CONCLUSIONS: Our results suggest that the presence of aminoglycoside-binding sites on RNA molecules may not be a useful trait for determining evolutionary relatedness. Instead, the fact that RNA molecules can bind these 'low molecular-weight effectors' may indicate that natural products such as aminoglycosides have evolved to exploit sequence- and structure-specific recognition of nucleic acids, in much the same way that lexitropsins have been designed by chemists to recognise specific nucleic acid sequences.