[Ampicillin and sulbactam concentrations in the irradiated mandible after oral squamous cell cancer]. / Untersuchungen zum Ampicillin/Sulbactam-Spiegel im bestrahlten Unterkieferknochen bei Patienten mit oralen Plattenepithelkarzinomen.

INTRODUCTION: Radiation therapy of the oral and maxillo-facial region increases the risk of an infected osteoradionecrosis (IORN) which is a severe complication. Therefore, perioperative antibiotics for the prophylaxis of ORN is a standard in clinical oncology. The combination therapy of ampicillin and sulbactam (Unacid) promises a good therapeutic and prophylactic outcome. PATIENTS: We compared the concentration of Unacid in bone and blood specimens of 22 irradiated patients. All patients were irradiated with 39.6 Gy prior to surgery. The specimens were obtained during the operation 3 weeks after the end of the radiation therapy. RESULTS: The concentration of ampicillin/sulbactam in the blood was 124.9/64.5 microg/ml. The bone specimens showed a concentration of ampicillin/sulbactam of 5.54/1.21 microg/g. The concentration of the antibiotic in the bone was three to four times lower than in non-irradiated patients. Nevertheless, this concentration exceeds the minimum inhibitory concentration for bacteria in the oral cavity such as streptcoccae (MHK90<0.25 microg/ml) or staphylococcae (MHK90=0.12-2.0 microg/ml). CONCLUSIONS: The results of this study suggest, that Unacid is an effective antibiotic in the prophylaxis of ORN in irradiated patients with head and neck tumors.

Cardiac output and shunt during voluntary activity at different temperatures in the turtle, Trachemys scripta.

Red-eared slider turtles (Trachemys scripta) were chronically instrumented with blood flow probes for a long-term study of voluntary behavior in an enriched laboratory setting. Cardiovascular measures consisting of total cardiac output (Q(tot)), pulmonary blood flow (Q(pul)), systemic blood flow (Q(sys)), net cardiac shunt (Q(shunt)), heart rate (HR), and stroke volume (SV) were obtained during spontaneous activity at a constant body temperature (Tb=2 degrees C) and at unstable (variable) T(b)'s ranging from 19 degrees to 37 degrees C. The effects of temperature and activity differed between the pulmonary and systemic circuits, with increases in Q(sys) due to HR alone, while both HR and SV contributed to gains in Q(pul). At stable 20 degrees C, cardiovascular responses during diving, submerged swimming, and walking were qualitatively similar, and increases in Q(tot) during activity ( approximately 2 x resting levels) were due to greater gains in Q(pul) than Q(sys). At unstable T(b)'s and in general, net Q(shunt) while active depended on the integration of individual physiological influences such as heating, cooling, and initial behavioral state acting on the cardiovascular system. During activity, net left-to-right (L-R) shunts predominated at constant T(b) of 20 degrees C (mean shunt fraction approximately 30%-40%), while both net L-R and right-to-left (R-L) shunts of varying size were found at unstable T(b)'s (19 degrees - 37 degrees C).

A model of vertebrate resting metabolic rate: balancing energetics and O2 transport in system design.

In vertebrates, maximal rates of oxygen consumption (V(O(2),max)) exceed resting rates (V(O(2),rest)) by an average factor of ten. This pattern of factorial scope has led to the hypothesis that V(O(2),rest) and V(O(2),max) are causally linked in vertebrates (aerobic capacity model, Bennett and Ruben, Science 206, 649-654, 1979). We propose an alternate theory that vertebrate resting metabolic rates are regulated at levels to optimize metabolic performance during activity, by reducing cardiovascular response times for O(2) transport. First, we argue that circulatory convection has the potential to be rate-limiting to vertebrate aerobic adjustment. We then show mathematically that incremental changes in convection requirements exhibit a nonlinear dependence on initial values. From this, a cost-benefit model is constructed, using energetics and blood-convection requirements, to predict the optimal fractional allocation to V(O(2),rest) in vertebrates as 11% of V(O(2),max). The implications of our results to vertebrate metabolic design and the evolution of endothermy are discussed.

No association between islet cell antibodies and Coxsackie B, mumps, rubella and cytomegalovirus antibodies in non-diabetic individuals aged 7-19 years.

Viral antibodies were tested in a cohort of 44 islet-cell antibody-positive individuals age 7-19 years, and 44 of their islet cell antibody-negative age and sex-matched classmates selected from a population study of 4208 pupils who had been screened for islet cell antibodies. Anti-coxsackie B1-5 IgM responses were detected in 14 of 44 (32%) of the islet cell antibody-positive subjects and in 7 of 44 (16%) control subjects. This difference did not reach the level of statistical significance. None of the islet cell antibody-positive subjects had specific IgM antibodies to mumps, rubella, or cytomegalovirus. There was also no increase in the prevalence or the mean titres of anti-mumps-IgG or IgA and anti-cytomegalovirus-IgG in islet cell antibody-positive subjects compared to control subjects. These results do not suggest any association between islet cell antibodies, and possibly insulitis, with recent mumps, rubella or cytomegalovirus infection. Further studies are required to clarify the relationship between islet cell antibodies and coxsackie B virus infections.