Changes in and dorsal to the rat suprachiasmatic nucleus during early pregnancy.

Circadian rhythms in behavior and physiology change as female mammals transition from one reproductive state to another. The mechanisms responsible for this plasticity are poorly understood. The suprachiasmatic nucleus (SCN) of the hypothalamus contains the primary circadian pacemaker in mammals, and a large portion of its efferent projections terminate in the ventral subparaventricular zone (vSPZ), which also plays important roles in rhythm regulation. To determine whether these regions might mediate changes in overt rhythms during early pregnancy, we first compared rhythms in Fos and Per2 protein expression in the SCN and vSPZ of diestrous and early pregnant rats maintained in a 12:12-h light/dark (LD) cycle. No differences in the Fos rhythm were seen in the SCN core, but in the SCN shell, elevated Fos expression was maintained throughout the light phase in pregnant, but not diestrous, rats. In the vSPZ, the Fos rhythm was bimodal in diestrous rats, but this rhythm was lost in pregnant rats. Peak Per2 expression was phase-advanced by 4 h in the SCN of pregnant rats, and some differences in Per2 expression were found in the vSPZ as well. To determine whether differences in Fos expression were due to altered responsivity to light, we next characterized light-induced Fos expression in the SCN and vSPZ of pregnant and diestrous rats in the mid-subjective day and night. We found that the SCN core of the two groups responded in the same way at each time of day, whereas the rhythm of Fos responsivity in the SCN shell and vSPZ differed between diestrous and pregnant rats. These results indicate that the SCN and vSPZ are functionally re-organized during early pregnancy, particularly in how they respond to the photic environment. These changes may contribute to changes in overt behavioral and physiological rhythms that occur at this time.

A role for culture in diagnosis of Helicobacter pylori-related gastric disease.

UNLABELLED: In this study, our objective was to determine the presence of Helicobacter pylori and other rapid urease-positive (RUP) organisms in gastric biopsies in 70 patients, 30 of whom had ulcers or erosions. A retrospective chart review was undertaken to correlate diagnostic tests (culture and direct urease) with results of endoscopic examination and the patient's clinical information. Eleven of 70 (15.7%) patients' biopsies were positive by both culture and direct urease for H. pylori, seven (10%) patients' biopsies were positive by culture only, and eight (11.4%) biopsies by direct urease only. Of 30 patients with ulcers (esophageal, antral, stomach, or duodenal), 15 had evidence of H. pylori infection by culture and/or direct urease test. In addition, patients with a positive direct urease test but a negative culture for H. pylori were more likely to have other rapid urease-positive organisms (RUP) isolated from their gastric biopsy cultures than patients with negative results from both tests. CONCLUSIONS: As a result of problems associated with commonly used diagnostic tests, a combination of tests performed on multiple biopsies is more sensitive and specific for the diagnosis of H. pylori infection than any single test. The common occurrence of RUP streptococcal and staphylococcal species in gastric biopsy tissue is demonstrated and proposed as a cause of false-positive direct urease tests.

Phenotypic switching of Thiobacillus ferrooxidans.

Two solid medium formulations, designated 100:10 and 10:10, were developed for the growth of Thiobacillus ferrooxidans. The new media contain a mixture of both ferrous iron and thiosulfate as available energy sources, permitting the detection of colony morphology variants that arise spontaneously in a wild-type population. Several morphological and physiological characteristics of a class of T. ferrooxidans variants, termed LSC for large spreading colony, are described. LSC variants lack the ability to oxidize iron but retain the capacity to utilize thiosulfate or tetrathionate as energy sources. An LSC colony spreads on the surface of solid 100:10 medium as a monolayer of cells in a fashion resembling that of certain swarming or gliding bacteria. The LSC variant reverts to a parental wild type at frequencies that vary in different independently arising isolates. The identity of the LSC variant as a derivative of the parental wild-type T. ferrooxidans was established by Southern blot hybridization.

Detection of antibodies to Neisseria gonorrhoeae by counterimmunoelectrophoresis.

Antigen was partially purified from Neisseria gonorrhoeae B370 saline wash and used to assay human sera for the presence of antibodies to N. gonorrhoeae. The antigen activity as monitored by counterimmunoelectrophoresis (CIE) is resistant to trypsin and papain but sensitive to heat and periodate oxidation. Of the sera from patients with bacteriologically confirmed cases of gonorrhea, 80% were positive by CIE using this antigen preparation. Of the sera in the negative control group 11% were reactive.