Changes in Escherichia coli resistance to co-trimoxazole in tuberculosis patients and in relation to co-trimoxazole prophylaxis in Thyolo,Malawi

In Thyolo district, Malawi, an operational research study is being conducted on the efficacy and feasibility of co-trimoxazole prophylaxis in preventing deaths in HIV-positive patients with tuberculosis (TB). A series of cross-sectional studies were carried out to determine i) whether faecal Escherichia coli (E.coli) resistance to co-trimoxazole in TB patients changed with time and ii) whether the resistance pattern was different in HIV positive TB patients who were taking co-trimoxazole prophylaxis. Co-trimoxazole resistance among E.coli isolates in TB patients at the time of registration was 60% in 1999 and 77% in 2001 (p<0.01). Resistance was 89% among HIV-infected TB patients (receiving co-trimoxazole), while in HIV negative patients (receiving anti-TB therapy alone) it was 62% (p<0.001). The study shows a significant increase of E.coli resistance to co-trimoxazole in TB patients which is particularly prominent in HIV infected patients on co-trimoxazole prophylaxis. Since a high degree of plasmid-mediated transfer of resistance exists between E.coli and the Salmonella species, these findings could herald limitations on the short and long term benefits to be anticipated from the use of co-trimoxazole prophylaxis in preventing non-typhoidal salmonella bacteraemia and enteritis in HIV infected TB patients in Malawi.     

Increased carbon monoxide levels in the nasal airways of subjects with a history of seasonal allergic rhinitis and in patients with upper respiratory tract infection

BACKGROUND: Carbon monoxide (CO) has emerged as an endogenously produced gaseous mediator known to be involved in bronchial smooth muscle regulation. Increased amounts of CO have been found in exhaled air during asthma and lower airway inflammation. Recently CO has been shown to be produced in the nasal airways, but there are no reports of altered CO levels in nasal airways during inflammation. OBJECTIVE: This study was designed to investigate if CO levels increase in the human nasal airways during inflammatory conditions, such as allergy and upper airway respiratory tract infection (URTI). METHODS: CO was sampled separately from the upper and lower airways of 13 healthy control subjects, six patients with a history of allergic rhinitis and six patients with URTI. RESULTS: Nasal CO levels were increased in subjects with allergic rhinitis, compared to healthy controls (2.07 +/- 0.15 ppm, n = 6 and 1.62 +/- 0.08 ppm, n = 13, respectively, P < 0.01). CO levels were also increased in patients with URTI, compared to the same controls (1.92 +/- 0.09 ppm, n = 6, P < 0.05). Normal levels of CO were found in air from the lower airways among subjects with allergic rhinitis, whereas corresponding levels in the URTI patients were increased. CONCLUSION: The present data demonstrates that upper airway CO levels increase in parallel with different inflammatory stimuli, such as allergy and infection, suggesting a role for CO as marker or mediator of nasal inflammation.     

Reliability of Cord Formation in BACTEC 12B/13A Media for Presumptive Identification of Mycobacterium tuberculosis Complex in Laboratories with a High Prevalence of Mycobacterium tuberculosis

A total of 1208 positive BACTEC vials were examined for the presence or absence of serpentine cording. A very high (92.9%) rate of laboratory prevalence was obtained for Mycobacterium tuberculosis complex. The sensitivity, specificity, positive and negative predictive values of this test were 92.7%, 95.3%, 99.6% and 50.0%, respectively. It was concluded that testing cord formation in laboratories that have a high prevalence of Mycobacterium tuberculosis complex is an exceptionally reliable method for preliminary reporting of cording-positive cases; however, for cording-negative cases, preliminary reports based solely on cord formation are not reliable. It was also observed that the length of the incubation period has a significant effect on cord formation. Incubation periods of 4 days or less are not sufficient to determine noncording in smears prepared from positive BACTEC vials. Electronic Publication     

The effect of increased nitrogen pressure on motor activity and the intercentral relationships of the brain of monkeys

The influence of increased nitrogen pressure up to 19 ata was investigated in chronic experiments on monkeys of a species of Javan macaques (Macaca irus)with electrodes implanted in cortical and subcortical regions of the brain. The phasic character of the changes of motor activity of the animals, an increase in the spectral density of the average power of the EEG in the range of frequencies from 4 to 20 Hz, and a disturbance in the connectedness of the electrogenesis of the reticular formation of the midbrain with the bioelectrical processes in the substantia nigra, the head of the caudate nucleus, and the frontal and motoric areas of the cortex were identified in the course of nitrogen compression at a rate of 1.0 ata per 1 min.Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 78, No. 3, pp. 26–32, March, 1992.     

Action of antiestrogens on the (Ca2+ + Mg2+)-ATPase and Na+/Ca2+ exchange of brain cortex membranes

The effect of tamoxifen (TAM) and other antiestrogens on the Ca2+ transport activity of synaptic plasma membranes (SPM) and microsomal membranes isolated from sheep brain cortex was investigated. The maximal (Ca2+ + Mg2+)-ATPase activity of SPM, which is reached at a pCa of about 6.0-6.5, is decreased by about 30% in the presence of 50 microM TAM, whereas the (Ca2+ + Mg2+)-ATPase activity of microsomes, which is maximal at a pCa of about 5.0, is decreased by about 90% by 50 microM TAM. In parallel experiments, we observed that the ATP-dependent Ca2+ uptake is also affected differently by TAM in the two membrane preparations. We found that 50 microM TAM inhibits SPM Ca2+ uptake by about 25-30%, whereas the ATP-dependent Ca2+ uptake by the microsomal fraction is inhibited by about 60%. No significant effect of TAM was observed on the Na+/Ca2+ exchange of either membrane system. The results indicate that TAM is a more potent inhibitor of the active, calmodulin-independent Ca2+ transport system of the intracellular membranes than of that of the plasma membranes, which is calmodulin-dependent. It appears that TAM inhibits calmodulin-mediated reactions, probably through its binding to calmodulin, as we showed previously. However, the Ca2+ transport system of microsomes, which does not depend on calmodulin, is also particularly sensitive to TAM.     

Administration of balanced or BCAA-enriched amino acid solution in septic rats. Effects on protein synthesis in the liver.

Total hepatic protein synthesis was measured in vivo with a flooding-dose technique, and the production of total secreted proteins, albumin, complement component C3, and seromucoid fraction was measured in perfused livers of septic rats that received one of three different solutions infused intravenously; Group 1 received 16.4% dextrose; Group 2 received Aminosyn (25% BCAA) in 10.6% dextrose, and Group 3 received Freamine HBC (45% BCAA) in 10.6% dextrose. All solutions were isocaloric, and the amino acid solutions were isonitrogenous. The solutions were administered for 18 or 48 hours after the induction of sepsis. There were no significant differences in mortality rates in the three treatment groups. The negative nitrogen balance seen in the dextrose-infused animals was reversed to the same degree by the two different amino acid solutions. There were no significant differences in hepatic protein synthesis rates in vivo between the three groups of rats. Synthesis rates of secreted proteins in perfused liver were similar in the different treatment groups in the 18-hour experiments, whereas in the 48-hour experiments, synthesis rates of total secreted proteins, C3, and the serumucoid fraction were higher in Group 1 than in Groups 2 and 3. The results suggest that administration of an amino acid solution improves nitrogen balance in sepsis, but that this effect is not caused by stimulated hepatic protein synthesis. The nitrogen-sparing effect during sepsis of a branched chain amino acid (BCAA)-enriched solution does not seem to be superior to that of a balanced amino acid solution.