Recruitment of ZipA to the septal ring of Escherichia coli is dependent on FtsZ and independent of FtsA

Cell division in prokaryotes is mediated by the septal ring. In Escherichia coli, this organelle consists of several essential division proteins, including FtsZ, FtsA, and ZipA. To gain more insight into how the structure is assembled, we studied the interdependence of FtsZ, FtsA, and ZipA localization using both immunofluorescence and Gfp tagging techniques. To this end, we constructed a set of strains allowing us to determine the cellular location of each of these three proteins in cells from which one of the other two had been specifically depleted. Our results show that ZipA fails to accumulate in a ring shape in the absence of FtsZ. Conversely, depletion of ZipA does not abolish formation of FtsZ rings but leads to a significant reduction in the number of rings per unit of cell mass. In addition, ZipA does not appear to require FtsA for assembly into the septal ring and vice versa. It is suggested that septal ring formation starts by assembly of the FtsZ ring, after which ZipA and FtsA join this structure in a mutually independent fashion through direct interactions with the FtsZ protein.     

Anisotropy of human muscle via non-invasive impedance measurements

Combining non-invasive 50 kHz impedance measurements with a mathematical model for the underlying structure, we obtain in vivo values for the transverse and longitudinal conductivities of the muscles of the human thigh and for the (isotropic) conductivity of the covering skin-fat layer. Results for a healthy male subject are in acceptably good agreement with those obtained elsewhere on surgically exposed or freshly excised animal tissue and with 'global' measurements on humans. Also, measurements using rotatable probes reveal orientations of underlying muscle fibres via minima in resistance versus angle curves. The results suggest potentially useful methods for studying muscle properties in clinical and physiological research.     

Long-term intravesical oxybutynin chloride therapy in children with myelodysplasia

PURPOSE: We evaluated the clinical use of long-term intravesical oxybutynin chloride in the treatment of neurogenic bladder dysfunction in children with myelodysplasia who could not tolerate oral anticholinergics. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients recommended for intravesical oxybutynin chloride therapy. A total of 12 girls and 18 boys 1 to 17 years old was recruited for study. Oxybutynin chloride (5 mg.) was instilled 2 times daily and pretreatment cystograms were compared to followup urodynamic studies. Duration of therapy was 2 to 26 months (mean 13, median 12). RESULTS: Mean total capacity plus or minus standard deviation increased from 209 +/- 103 to 282 +/- 148 ml. (p < 0.01), mean safe capacity increased from 157 +/- 105 to 234 +/- 147 ml. (p < 0.01) and mean age adjusted safe capacity increased from 76 +/- 36 to 115 +/- 62%. Of the 29 patients who were incontinent 3 (10%) achieved continence and 19 (65%) reported a decreased use of sanitary pads. None of the patients had systemic side effects related to intravesical treatment. CONCLUSIONS: We believe that intravesical oxybutynin chloride is a viable treatment option for patients with myelodysplasia in whom oral therapy fails.     

Comparison of methods of identifying Helicobacter hepaticus in B6C3F1 mice used in a carcinogenesis bioassay

In a long-term rodent bioassay evaluating the carcinogenicity of triethanolamine, there was equivocal evidence of carcinogenic activity in male B6C3F1 mice, based on a marginal increase in the number of hepatocellular adenomas and hepatoblastomas. Interpretation was complicated by the presence of Helicobacter hepaticus in selected silver-stained liver sections which also had histological evidence of karyomegaly and oval cell hyperplasia. An increase in numbers of liver tumors, as evidence of carcinogenic activity, was also noted in female mice. However, H. hepaticus was not considered a complicating factor, because the livers of the female mice did not have histological features compatible with H. hepaticus infection. A retrospective analysis of 51 liver tissue samples from the original carcinogenicity study was conducted to determine the incidence of H. hepaticus infection and to evaluate different diagnostic approaches for assessing the presence of H. hepaticus in livers lacking characteristic lesions. In an initial evaluation of seven mice with liver tumors, argyrophilic bacteria resembling H. hepaticus were observed in liver sections, associated with characteristic liver lesions of hepatocytic karyomegaly and oval cell hyperplasia. Frozen liver tissue was available from four of these mice; all were confirmed to be infected with H. hepaticus by culture and PCR. In a larger subsequent analysis using frozen liver tissues from 44 mice without characteristic hepatic lesions, H. hepaticus-specific DNA was amplified from the livers of 21 of 44 of the mice (47%), compared to 14 of 44 of the mice (32%) having H. hepaticus cultured from their frozen liver tumors. The results of H. hepaticus culture and H. hepaticus-specific PCR concurred (i.e., both positive and negative results) in 84% of the cases. Microscopic detection of immunofluorescence-labeled or silver-stained bacteria in liver sections was relatively insensitive compared to either culture or PCR detection. This study confirms the widespread prevalence of H. hepaticus in mice, its potential to confound experimental results, and the need to include diagnostic testing for H. hepaticus in a murine health monitoring program.     

Apomorphine-induced yawning in the rat: influence of fasting and time of day

Yawning behavior is an experimental tool to study physiological responses, to elucidate the mechanisms of action of some drugs and hormones, and it is also a paradigm for some diseases and for dopamine (DA) agonists' clinical use. In this study, the effects of 24- and 48-h fasting as well as the influence of the light-dark cycle on apomorphine (APO)-induced yawning were evaluated. Initially, control and 48-h-fasted adult male rats were tested for yawning induced by APO (50, 100, 150 micrograms/kg, SC). The most effective dose tested was 100 micrograms/kg. Fasting significantly lowered yawning in all doses tested. Comparison between 24- and 48-h-fasted rats for APO (100 micrograms/kg)-induced yawning showed no significant difference between groups. Ad lib-fed groups were tested for APO (100 micrograms/kg)-induced yawning in both the light and in the dark phases of the cycle. Total number of yawnings increased significantly in the dark period. The present data show that fasting reduces and dark period increases APO-induced yawning in rats, suggesting that these conditions modulate the expression of this behavior.