Differences in susceptibility of inbred mice to Bacillus anthracis.

Animal species differ in their resistance both to infection by Bacillus anthracis and to anthrax toxin. A mouse model was developed to study the basis of the host differences and the pathogenesis of infection. When mice were infected with the virulent B. anthracis strain Vollum 1B, low 50% lethal dose (LD50) values (5 to 30 spores) were found for all 10 strains of inbred mice tested. However, analysis of time-to-death data revealed significant differences among the strains, which could be divided into three groups: most susceptible (A/J and DBA/2J); least susceptible (CBA/J, BALB/cJ, and C57BR/cdJ); and intermediate (the remaining five strains). In contrast, the mice were distinctly susceptible or resistant to lethal infection by the toxigenic, nonencapsulated Sterne vaccine strain. The LD50 for the susceptible A/J and DBA/2J mice was approximately 10(3) spores of the Sterne strain, whereas the remaining eight relatively resistant strains were killed only by 10(6) or more spores. F1 hybrid and backcross studies suggested that resistance to the Sterne strain is determined by a single dominant gene or gene complex. Mice lethally infected with B. anthracis showed an acute course of infection, characterized by extensive gelatinous edema and large concentrations of bacilli in the blood and organs (e.g., 10(9) CFU/g of spleen). The susceptibility of A/J and CBA/J mice to intravenously injected anthrax toxin components appeared to differ from their susceptibility to infection. The toxin LD50 values for both strains were similar. However, CBA/J mice died sooner than did A/J mice, with mean time to death of 0.9 and 3.7 days, respectively, in mice given 4 LD50 of toxin. The mouse model appears to be useful in studies on host resistance to anthrax and on the pathogenesis of the infection.     

A monoclonal blocking EIA for herpes simplex virus type 2 antibody: validation for seroepidemiological studies in Africa

A competitive type-specific enzyme-linked immunosorbent assay (ELISA) for herpes simplex virus type 2 (HSV-2) antibody was developed using an infected cell antigen and a monoclonal antibody to glycoprotein G-2. This assay has been validated for use for epidemiological studies using a large panel of sera collected in rural Uganda and a panel of 143 sera characterised previously by Western blotting, the 'gold standard' for HSV type-specific serology. This evaluation was found to have a sensitivity of 96% and a specificity of 91% in comparison with Western blot on 143 sera from clinic patients. The ELISA had a sensitivity of 93% and a specificity of 91% in comparison with Western blot on 495 sera collected in Uganda. The assay showed good reproducibility and a low percentage of sera gave equivocal results, indicating its suitability for epidemiological studies.     

Acute energetic effects of daunomycin on rabbit heart muscle

The acute effects of daunomycin on the mechanical and energetic outputs of rabbit papillary muscles have been examined at 27 degrees C using a myothermic technique. Contrary to expectations, daunomycin, in concentrations ranging from 10 to 160 micrograms/ml, acted as a positive inotropic agent in terms of peak stress development and work output. The rate of stress development was, however, slightly depressed, and the major mechanical effect of the drug was to prolong the relaxation phase so that there were large drug-dependent increments in the stress-time integral. Daunomycin at a concentration of 80 micrograms/ml produced a 22% increment in peak stress development and a 74% increment in stress-time integral. The linear relationship between total (active + passive) stress and heat production was altered such that there was a 73% increment in the activation heat component (intercept) and a 37% increase in the energy cost per unit stress development (slope). In afterloaded isotonic contractions, daunomycin increased the mean work output (W; averaged over all load levels) by 49%, but there was an even greater increment in the associated energy expenditure, ET, which rose by 66%. Consequently, the overall mechanical efficiency (W/ET X 100%) fell slightly. It is concluded that, in the rabbit, daunomycin in the acute situation increases total calcium delivery to the myofilaments and decreases the "apparent" transduction efficiency. These acute effects are the opposite of those reported in papillary muscles taken from rabbits in cardiac failure induced by chronic daunomycin administration. The short-term effects of daunomycin in the rabbit differ substantially from those seen in the rat and guinea pig.     

Randomized clinical trial of intrapartum clindamycin cream for reduction of group B streptococcal maternal and neonatal colonization

Objective: In a randomized trial, we sought to determine whether 2% clindamycin cream administered intravaginally during labor to group B streptococcal-colonized pregnant women without risk factors would decrease maternal and neonatal colonization.Methods: The eligible women were randomized to receive either cream or no treatment. Two hours after treatment or admission, the patients were tested with rectal and vaginal cultures. The neonates of the study patients were also tested.Results: Of women randomized to cream, 5 of 5 remained positive and 2 (33%) of their 6 neonates were positive. Of 4 randomized to no treatment, 3 (75%) remained positive and 1 (25%) of 4 neonates was positive.Conclusions: Intravaginal 2% clindamycin cream was ineffective in reducing colonization with group B streptococci.     

Simultaneous adrenal and cervical pheochromocytomas in childhood.

Pheochromocytoma is an uncommon tumor in childhood. The simultaneous occurrence of adrenal and cervical pheochromocytomas is a rare phenomenon; to our knowledge, this combination has been reported in the literature only once. Cervical pheochromocytomas are more accurately termed "aorticosympathetic paragangliomas." In children, 50% of pheochromocytomas are bilateral, multiple, or extra-adrenal. An increased familial incidence in the form of simple mendelian dominance is also noted in the pediatric age group. Bolus nephrotomography is extremely effective in identifying adrenal pheochromocytomas in children. To prepare the patient for surgery, and alpha-adrenergic blocking agent is administered from 7 to 10 days before operation and a beta-blocking agent is administered 3 days before. A transabdominal approach is essential because of the frequent extra-adrenal sites and multicentricity of the tumor in children.