Definition of Mycobacterium tuberculosis culture filtrate proteins by two-dimensional polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and electrospray mass spectrometry.

A number of the culture filtrate proteins secreted by Mycobacterium tuberculosis are known to contribute to the immunology of tuberculosis and to possess enzymatic activities associated with pathogenicity. However, a complete analysis of the protein composition of this fraction has been lacking. By using two-dimensional polyacrylamide gel electrophoresis, detailed maps of the culture filtrate proteins of M. tuberculosis H37Rv were generated. In total, 205 protein spots were observed. The coupling of this electrophoretic technique with Western blot analysis allowed the identification and mapping of 32 proteins. Further molecular characterization of abundant proteins within this fraction was achieved by N-terminal amino acid sequencing and liquid chromatography-mass spectrometry. Eighteen proteins were subjected to N-group analysis; of these, only 10 could be sequenced by Edman degradation. Among the most interesting were a novel 52-kDa protein demonstrating significant homology to an alpha-hydroxysteroid dehydrogenase of Eubacterium sp. strain VPI 12708, a 25-kDa protein corresponding to open reading frame 28 of the M. tuberculosis cosmid MTCY1A11, and a 31-kDa protein exhibiting an amino acid sequence identical to that of antigen 85A and 85B. This latter product migrated with an isoelectric point between those of antigen 85A and 85C but did not react with the antibody specific for this complex, suggesting that there is a fourth member of the antigen 85 complex. Novel N-terminal amino acid sequences were obtained for three additional culture filtrate proteins; however, these did not yield significant homology to known protein sequences. A protein cluster of 85 to 88 kDa, recognized by the monoclonal antibodies IT-57 and IT-42 and known to react with sera from a large proportion of tuberculosis patients, was refractory to N-group analysis. Nevertheless, mass spectrometry of peptides obtained from one member of this complex identified it as the M. tuberculosis KatG catalase/peroxidase. Thus, the detailed mapping of M. tuberculosis proteins, combined with state-of-the-art analytical techniques such as mass spectrometry, provides a basis for further analysis and rapid identification of biologically relevant molecules.     

Occupational mortality from gastric and duodenal ulcer.

The pronounced geographical and temporal variations in gastric and duodenal ulcer suggest that important environmental factors must play a part in their aetiology. To determine the nature of possible factors, the Registrar General's decennial supplement and the vital statistics special reports of the United States Department of Health, Education, and Welfare on occupational mortality were analysed for occupation-specific mortality from peptic ulcer. The data disclose a high mortality from both types of ulcer among manual workers and a low mortality among sedentary occupations. This general pattern runs parallel to a low mortality from gastric and duodenal ulcer among the high social classes and a high mortality in the low social classes. Married women displayed a gradient of gastric ulcer mortality increasing from social class 1 to social class 5 but gave no evidence of social class correlation with respect to duodenal ulcer. The significant correlation between mortality from gastric and duodenal ulcer among different occupations could suggest that both types of ulcer hold some of the precipitating environmental risks in common. In duodenal ulcer the varying extent of energy expenditure among different occupations may be responsible for the different risk of contracting duodenal ulcer and dying from it. The association between energy expenditure and peptic ulcer mortality seems to be less important for gastric ulcer where additional factors associated with social class may also be operating.     

Renal regulation of salt balance: a primer for non-purists

The greater than 40-fold range of voluntary salt intake in humans requires corresponding adjustments in renal excretion to maintain balance. Although many mechanisms have been implicated in the regulation of salt output by the kidney, surprisingly little consideration has been given to their quantitative significance and possible interaction. This survey summarizes the effects of changes in glomerular filtration rate, proximal peritubular physical factors, and plasma concentrations of aldosterone and atrial natriuretic factor (ANF), singly and in combination, on the level of salt excretion. Contrary to expectation, even large increases in filtration or decreases in proximal reabsorption have only minor natriuretic effects, due to constancy of fractional reabsorption in downstream nephron segments. Lack of aldosterone release increases salt excretion as much or more than the upstream mechanisms, whereas ANF-induced inhibition of reabsorption in the medullary collccting duct has the largest effect. It may be concluded, therefore, that the potency of these natriuretic factors increases with distance along the nephron, even though each is operating on a progressively small tubular load. However, none of the mechanisms, in isolation, is sufficient to explain salt balance over the range of voluntary intake. Combination of factors demonstrates synergism rather than simple additivity, resulting in more than enough reserve capacity for salt excretion.     

Improving the retention rate of newly graduated nurses.

Newly graduated nurses often finish orientation and then believe they still need more support and mentoring than is available. Retention rates suffer as they think it must be better elsewhere. This article reports a community hospital's implementation of an education-based preceptor program. A convenience sample of 40 new graduates participated in the study. Qualitative and quantitative findings indicate a high level of satisfaction (mean visual analogue scale score 93.7), 29% increase in retention, and 9.5% decrease in vacancy.     

Associations of peptic ulcer and gastric cancer with other diseases in US veterans.

OBJECTIVES: The purpose of this study was to examine, through the database of the Department of Veterans Affairs, the joint occurrence of different diseases in individual patients. METHODS: Patients with a diagnosis of gastric cancer, gastric ulcer, or duodenal ulcer were extracted from the 1987 through 1990 computer files. A random sample of patients from each annual file served as a control population. All previous discharges of each case or control patient between 1970 and 1990 were searched for the occurrence of hypertensive diseases or chronic diseases of the joints, lungs, pancreas, and liver. The relative frequencies of such diagnoses in case and control patients were compared by multivariate logistic regression. RESULTS: Gastric ulcer and duodenal ulcer, but not gastric cancer, were significantly associated with chronic diseases of the joints, lungs, pancreas, and liver. None of the three diagnoses showed any significant association with hypertensive diseases. CONCLUSIONS: These relationships may reflect the influence of nonsteroidal anti-inflammatory drugs, smoking, and alcohol. They stress the importance of environmental risk factors other than Helicobacter pylori in terms of damage to the upper gastrointestinal mucosa.     

The physiological regulation of toll-like receptor expression and function in humans

Eleven mammalian toll-like receptors (TLRs 1–11) have been identified to date and are known to play a crucial role in the regulation of immune responses; however, the factors that regulate TLR expression and function in vivo are poorly understood. Therefore, in the present study, we investigated the physiological regulation of TLR expression and function in humans. To examine the influence of diurnal rhythmicity on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 8) at time points coinciding with the peak and nadir in the endogenous circulating cortisol concentration. While no diurnal rhythmicity in the expression of TLRs 1, 2, 4 or 9 was observed, the upregulation of costimulatory (CD80 and CD86) and antigen-presenting (MHC class II) molecules on CD14⁺ monocytes following activation with specific TLR ligands was greater ( P < 0.05) in samples obtained in the evening compared with the morning. To examine the influence of physical stress on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 11) at rest and following 1.5 h of strenuous exercise in the heat (34°C). Strenuous exercise resulted in a decrease ( P < 0.005) in the expression of TLRs 1, 2 and 4 on CD14⁺ monocytes. Furthermore, the upregulation of CD80, CD86, MHC class II and interleukin-6 by CD14⁺ monocytes following activation with specific TLR ligands was decreased ( P < 0.05) in samples obtained following exercise compared with at rest. These results demonstrate that TLR function is subject to modulation under physiological conditions in vivo and provide evidence for the role of immunomodulatory hormones in the regulation of TLR function.     

Was belastet in der Feuerwehr?

Background: Previous studies investigated extreme stress of ambulance personnel, where post-traumatic stress disorder dominated as far as the consequences were concerned. Recent studies are being led by the assumption that daily stress can increase the vulnerability with regard to psychological and health impairments. Aim: In the study, the main focus is placed on which daily stress exposures are of importance in the fire brigade and how they correlate with the personal health of the fire fighters. Burnout and the reduced habitual physical well-being are being examined as potential impairments. Method: Data was gathered from fire fighting personnel working in Berlin and Saxony-Anhalt by means of a questionnaire. Responses of 364 (response rate 40%) fire fighting personnel were analyzed by performing univariate, bivariate and multivariate analyses. A frame model “stress — burnout — physical well-being” is examined by using structural equation modelling (Lisrel). Results: Work-related obstacles in every-day life are of the greatest importance in the fire brigade’s daily work; extreme stress is being experienced rather seldom in comparison. Unfavorable general conditions of work organization correlate with higher burnout levels. The analyzed frame model — work-related stress influences burnout, burnout as an predictor for impairments of well-being — exhibits a satisfactory level of model fit. Conclusions: The results support the assumption that burnout has an intermediating effect on the relation of work-related stress and health. Therefore, the possibility of achieving a reduction of work organizational stress in order to lower the probability of long-term health impairments exists in the fire brigade.     

Characteristics of protective immunity engendered by vaccination of mice with purified culture filtrate protein antigens of Mycobacterium tuberculosis.

In this study highly purified culture filtrate proteins obtained from Mycobacterium tuberculosis strains Erdman and H37Rv were tested for their capacity to stimulate immune T cells in vitro, and to immunize mice in vivo. Analysis of the culture filtrate antigen pool revealed a complex mixture of proteins; after separation of this pool into fractions of defined molecular size using an electrophoretic method, it was found that multiple fractions strongly stimulated interferon-gamma (IFN-gamma) secretion by immune CD4 T cells in vitro. In a further series of experiments mice were given multiple immunizations with the culture filtrate protein pool suspended in emulsions of incomplete Freund's adjuvant. Such mice were as resistant as mice given live bacillus Calmette-Guérin (BCG) vaccine to a low dose aerosol challenge infection with M. tuberculosis, but this resistance waned to low levels by 5 months post-vaccination. Furthermore, experiments using the filtrate antigens to boost or augment immunity induced by the BCG vaccination itself were unsuccessful. These data therefore support the hypothesis that the culture filtrate proteins of M. tuberculosis contain multiple antigens that are strongly recognized by T cells acquired during the initial expression of protective immunity to tuberculosis. Conventional immunization with these purified protein antigens can engender a strong degree of protective immunity, but this immunity is apparently not sustained at the same level as that induced by the live vaccine, perhaps suggesting a lack of suitable stimulation of memory immunity.