Tumor growth parameters of in-vivo human breast carcinoma: a proposed mathematical model for tumor growth kinetics

Many mathematical models have been proposed to study tumor growth parameters in vivo. Nevertheless most of the medical models have given variable results even when experimental conditions are exactly the same. There are multiple factors that are capable of affecting tumor growth that should be taken into account when proposing a mathematical model for tumor growth in vivo. We discuss here own proposed model for tumor growth kinetics utilizing a modified Gompertz function that better responds to the growth characteristic of in "vivo" tumors.     

A community outbreak of tuberculosis in Southern Austria: lessons learned for a targeted use of molecular epidemiological methods and tuberculin skin testing

A cluster of 10 cases of tuberculosis disease (one of them extrapulmonary) occurred from July 2001 until November 2003 in a health district in Southern Austria. Eight patients were culture confirmed and shared an identical strain. One of these eight cases was identified as outbreak-related by molecular strain typing only. Due to public pressure, a further 600 persons received chest X-ray and clinical examinations. Apart from one case which could be excluded from the outbreak because of a different strain pattern, no outbreak-related case of active tuberculosis was detected by this non-targeted procedure. Tuberculin skin testing, not part of the Austrian routine protocol of contact investigation in adults, was initiated after diagnosis of case 8. Forty-nine latently infected contacts were detected. Population-based genotyping of all isolates, prioritization of contact investigations and early use of targeted tuberculin skin testing are critical for effective tuberculosis control in low-incidence countries.     

Serving in Bosnia made me appreciate living in Bristol: stressful experiences, attitudes, and psychological needs of members of the United Kingdom Armed Forces

Peacekeeping operations form an increasing part of the role of the U.K. Armed Forces. This study identified perceived needs for training before such operations, experiences of stress during deployments, beliefs and attitudes regarding psychological support and debriefing on return, general attitudes toward peacekeeping duties, and positive aspects of the peacekeeping role. Although nearly all peacekeepers were exposed to a variety of experiences, most perceived stress came from professional difficulties and frustrations with the occupational role of being a peacekeeper, rather than from dangerous situations. The exception was a significant fear of land mines. For many, peacekeeping had a positive impact on soldiers' lives, most commonly an appreciation of "things back home." Respondents' opinions about the peacekeeping experience vary greatly. Additional training addressing and exploring potential conflicts between the traditional role of the soldier and the role of the peacekeeper may be useful.     

Exercising in environmental extremes : a greater threat to immune function?

Athletes, military personnel, fire fighters, mountaineers and astronauts may be required to perform in environmental extremes (e.g. heat, cold, high altitude and microgravity). Exercising in hot versus thermoneutral conditions (where core temperature is > or = 1 degrees C higher in hot conditions) augments circulating stress hormones, catecholamines and cytokines with associated increases in circulating leukocytes. Studies that have clamped the rise in core temperature during exercise (by exercising in cool water) demonstrate a large contribution of the rise in core temperature in the leukocytosis and cytokinaemia of exercise. However, with the exception of lowered stimulated lymphocyte responses after exercise in the heat, and in exertional heat illness patients (core temperature > 40 degrees C), recent laboratory studies show a limited effect of exercise in the heat on neutrophil function, monocyte function, natural killer cell activity and mucosal immunity. Therefore, most of the available evidence does not support the contention that exercising in the heat poses a greater threat to immune function (vs thermoneutral conditions). From a critical standpoint, due to ethical committee restrictions, most laboratory studies have evoked modest core temperature responses (< 39 degrees C). Given that core temperature during exercise in the field often exceeds levels associated with fever and hyperthermia (approximately 39.5 degrees C) field studies may provide an opportunity to determine the effects of severe heat stress on immunity. Field studies may also provide insight into the possible involvement of immune modulation in the aetiology of exertional heat stroke (core temperature > 40.6 degrees C) and identify the effects of acclimatisation on neuroendocrine and immune responses to exercise-heat stress. Laboratory studies can provide useful information by, for example, applying the thermal clamp model to examine the involvement of the rise in core temperature in the functional immune modifications associated with prolonged exercise. Studies investigating the effects of cold, high altitude and microgravity on immunity and infection incidence are often hindered by extraneous stressors (e.g. isolation). Nevertheless, the available evidence does not support the popular belief that short- or long-term cold exposure, with or without exercise, suppresses immunity and increases infection incidence. In fact, controlled laboratory studies indicate immuno-stimulatory effects of cold exposure. Although some evidence shows that ascent to high altitude increases infection incidence, clear conclusions are difficult to make because of some overlap with the symptoms of acute mountain sickness. Studies have reported suppressed cell-mediated immunity in mountaineers at high altitude and in astronauts after re-entering the normal gravity environment; however, the impact of this finding on resistance to infection remains unclear.