Decreased virulence of a pneumolysin-deficient strain of Streptococcus pneumoniae in murine meningitis

Pneumolysin, neuraminidases A and B, and hyaluronidase are virulence factors of Streptococcus pneumoniae that appear to be involved in the pathogenesis of meningitis. In a murine model of meningitis after intracerebral infection using mutants of S. pneumoniae D39, only mice infected with a pneumolysin-deficient strain were healthier at 32 and 36 h, had lower bacterial titers in blood at 36 h, and survived longer than the D39 parent strain. Cerebellar and spleen bacterial titers, meningeal inflammation, and neuronal damage scores remained uninfluenced by the lack of any of the virulence factors.     

Experimental pneumococcal meningitis: impaired clearance of bacteria from the blood due to increased apoptosis in the spleen in Bcl-2-deficient mice

Necrotic and apoptotic neuronal cell death can be found in pneumococcal meningitis. We investigated the role of Bcl-2 as an antiapoptotic gene product in pneumococcal meningitis using Bcl-2 knockout (Bcl-2(-/-)) mice. By using a model of pneumococcal meningitis induced by intracerebral infection, Bcl-2-deficient mice and control littermates were assessed by clinical score and a tight rope test at 0, 12, 24, 32, and 36 h after infection. Then mice were sacrificed, the bacterial titers in blood, spleen, and cerebellar homogenates were determined, and the brain and spleen were evaluated histologically. The Bcl-2-deficient mice developed more severe clinical illness, and there were significant differences in the clinical score at 24, 32, and 36 h and in the tight rope test at 12 and 32 h. The bacterial titers in the blood were greater in Bcl-2-deficient mice than in the controls (7.46 +/- 1.93 log CFU/ml versus 5.16 +/- 0.96 log CFU/ml [mean +/- standard deviation]; P < 0.01). Neuronal damage was most prominent in the hippocampal formation, but there were no significant differences between groups. In situ tailing revealed only a few apoptotic neurons in the brain. In the spleen, however, there were significantly more apoptotic leukocytes in Bcl-2-deficient mice than in controls (5,148 +/- 3,406 leukocytes/mm2 versus 1,070 +/- 395 leukocytes/mm2; P < 0.005). Bcl-2 appears to counteract sepsis-induced apoptosis of splenic lymphocytes, thereby enhancing clearance of bacteria from the blood.     

How well does reflectance pulse oximetry reflect intrapartum fetal acidosis?

OBJECTIVE: The purpose of this study was to determine the sensitivity and specificity for acidosis of intrapartum fetal oxygen saturation measured by reflectance pulse oximetry. STUDY DESIGN: Intrapartum fetal oxygen saturation values per labor stage were correlated with umbilical artery pH, base excess and PCO(2) by regression analysis. Receiver operating characteristic curve analysis was performed with the use of historic umbilical arterial cutoff values; a fetal oxygen saturation cutoff range with optimal sensitivity and specificity was calculated. RESULTS: Mean fetal oxygen saturation was 42.8%, over the mean 132 minutes of 107 recordings. Overall areas under the sensitivity and specificity curves were 0.77 for pH and PCO(2), decreasing sharply toward birth; all areas for base excess were poor (approximately 0.5). Depending on stage and umbilical artery parameter, fetal oxygen saturation cutoffs were 33% to 36%, with sensitivities of 0.67 to 0.8 and specificities of 0.62 to 0.90. CONCLUSION: Fetal oxygen saturation sensitivities and specificities for acidosis do not yet justify the supplementation of cardiotocography with routine reflectance pulse oximetry.     

Gustatory and olfactory function in the first trimester of pregnancy.

OBJECTIVE: To investigate gustatory and olfactory sensitivity in the first trimester of pregnancy using validated test kits. DESIGN: Prospective study. SETTING: Department of Obstetrics, University Hospital Zurich, Switzerland. POPULATION: Total 53 pregnant women and 59 controls in a known phase of the menstrual cycle. METHOD: Gustatory sensitivity was assessed by requiring subjects to discriminate between four basic-taste tablets ('sweet', 'salty', 'sour', and 'bitter'). Olfactory testing was performed using the 'Sniffin' sticks' kit. Subjects rated the intensity and hedonic tone of the four tastants and of 10 common odors. RESULTS: Pregnant women had significantly lower overall gustatory sensitivity scores. There were no differences in olfactory sensitivity. However, pregnant women rated the odors 'rum', 'cigarette' and 'coffee' as more aversive than did non-pregnant women. CONCLUSION: Our data do not support the hypothesis of a generalized increase in chemosensitivity in early pregnancy. In terms of adaptive changes of the olfactory system may act as a sentinel to potentially harmful chemicals. In contrast, the gustatory system appears to retreat to allow a greater intake of electrolytes and a more widely sourced diet.     

Functional significance of the hippocampus

The alimentary conditioned reflex to time was manifested in a motor reaction of the unrestrained dog to the food cup. Latencies of responding and running speeds were measured to within hundredths of a second. The conditioned stimuli were presented in a stereotype. Before the lesions the dogs were performing to the time factor alone, i.e. without presentation of the stimuli. Hippocampal lesions resulted in a complete disappearance of the well established conditioned reflexes to time with intervals of 30 sec, 1, 2 and 5 min. In spite of the long training (over two years) the hippocampectomized dogs failed to recover the conditioned reflexes to time. At the same time hippocampal lesions hardly affected the positive conditioned reflexes and discrimination of single and complex conditioned stimuli. The hippocampus appears to be involved both in the mechanisms of remembering the time count and in trace processes underlying memory. Lesions in the parietal cortex and underlying white matter impaired neither reflexes to time, nor those to the stimuli.     

Xanthogranulomatous pyelonephritis. Unusual clinical presentations

The association of xanthogranulomatous pyelonephritis with renal-cell carcinoma and the loss of a kidney homograft because of this disorder suggest that in certain cases altered immunologic competence might be an etiologic factor in this disease. This entity may develop acutely over a four-month period and can occur during the first year of life. It is not necessarily associated with non-function of the involved kidney during excretory urography. Xanthogranulomatous pyelonephritis may be a segmental renal disease and may also occur bilaterally. Subtotal nephrectomy is the treatment of choice in these instances. Studies of calcium and phosphorus excretion in patients with this disease should be implemented in an effort to clarify the pathophysiologic aspects of the disease.