Electron microscopy of the canine corneal basement membranes

The purpose of this study was to characterize the surface topographical features of the epithelial and endothelial (Descemet's) basement membranes of the canine cornea. Corneas were obtained from young, healthy dogs (<2 years old) with no history or evidence of previous ocular disease. The epithelium and endothelium was carefully removed preserving the anterior and posterior basement membranes. The specimens were examined by transmission electron microscopy and scanning electron microscopy. The epithelial and endothelial basement membrane surface topography is an intricate meshwork of pores and fibers measuring in the nanometer size range. The features of the endothelial basement membrane overall are smaller in size than the epithelial basement membrane. These surface topographical features may incite changes in epithelial and endothelial cell behavior.     

Prevalence of hepatitis B virus infection among women at reproductive age at a German university hospital

BACKGROUND: Mother to infant transmission of hepatitis B virus (HBV) represents a major factor in maintaining chronic infection and depends on the degree of maternal infectivity status. OBJECTIVES: To examine the seroprevalence of hepatitis B virus surface antigen (HBsAg) in women at reproductive age admitted to the Department of Gynaecology at a German university hospital. STUDY DESIGN: The seroprevalence of hepatitis B surface antigen (HBsAg) in 5518 women at reproductive age was examined, HBsAg-positive samples were tested for additional HBV markers to verify the infection status. RESULTS: Out of 5518 samples from women at reproductive age, 88 women (1.59%) were positive for HBsAg and 7 of these HBV-positive women (7.95%) were additionally positive for HBeAg. The majority of the study population were German citizens, however most HBV infected persons originated from countries with a high HBV prevalence. The HBV seroprevalence in our study group is about two times higher compared to the average seroprevalence in the German citizen adult population, thus probably resulting in an underestimation of the infection rate in a multinational setting. CONCLUSIONS: Screening for HBsAg during pregnancy is still necessary and important for reduction of perinatal HBV transmission even in countries with low HBV prevalence.     

PCR-based DNA fingerprinting of Staphylococcus haemolyticus to investigate nosocomial infections

Objective: To apply PCR-based DNA fingerprinting in a clinical microbiology laboratory to investigate nosocomial infections with Staphylococcus haemolyticus.
Method: DNA fingerprints were generated by PCR on 99 S. haemolyticus isolates using different primer combinations based on ERIC, REP or arbitrarily chosen simple repeat sequences.
Results: Primer combinations REP1+(GTC)₆ and ERIC1+ERIC2 had sufficient discrimatory power and were chosen to analyze the clinical isolates. DNA fingerprint patterns from strains isolated from the patients nursed in the same hospital ward in the period 1991–94 were approximately 90% similar to each other. One staff member, sampled in 1991, carried a strain with a similar fingerprint.
Conclusions: PCR based DNA fingerprinting is a suitable method to perform in a clinical laboratory. An S. haemolyticus strain appeared to be endemic in the hospital ward and had most probably been transmitted from patient to patient. S. haemolyticus may carry glycopeptide resistance and needs attention as a causative agent of nosocomial infections.     

Influence of Adipose Tissue Blood Flow on the Lipolytic Response to Circulating Noradrenaline at Normal and Reduced pH

Hypercapnic acidosis (pH 7.0) inhibits the lipolytic response of canine subcutaneous adipose tissue to i.v. infused noradrenaline (NA) by 80 per cent or more. The response to sympathetic nerve stimulation, on the other hand, is only reduced by 1040 per cent during acidosis. The fate of intravenously infused ³H-labelled NA (0.35 ug × kg^-1× min^-1 for 30 min) was not significantly altered by acidosis. The rate of disappearance of unmetabolized NA from the arterial plasma after an infusion was the same at pH 7.4 and 7.0 and the calculated increase in circulating NA during infusions was 4 ng/ml at both pH:s. I.v. infusion of Na increases adipose tissue blood flow, an effect which is attenuated by acidosis. There was a significant correlation (p< 0.001) between adipose tissue blood flow and the lipolytic response at normal pH. Preventing the NA-induced increase in blood flow by constant flow perfusion reduced the lipolytic response at normal pH. The degree of inhibition by acidosis of the lipolytic response to i.v. NA was significantly reduced (from 79 to 56 per cent, p < 0.05) when the adipose tissue was perfused at constant flow. These data suggest that adipose tissue blood flow is important in determining the lipolytic response to i.v. NA, probably by influencing the delivery of NA to the tissue. The marked inhibition by acidosis of lipolysis due to i.v. infused NA therefore appears to be the combined effect of a direct antilipolytic effect of acidosis and a decreased delivery of N A to the adipose tissue due to the attenuated blood flow response.     

Enzymatic activities induced by interferon in human fibroblast cell lines differing in their sensitivity to the anticellular activity of interferon

IF^r, a subline of transformed human fibroblast cells, which is sensitive to the antiviral but resistant to the anticellular activity of interferon, was found to be equally well inducible as its parental cell line RSa for the two major interferon-mediated double-stranded RNA-dependent enzymatic activities, 2–5A synthetase and 73K phosphoprotein kinase. The induction of 2-5A synthetase as a function of interferon dose, the specific activity of the 2-5A synthetase, the nature of the 2-5A oligonucleotide products, and the activity of the 2-5A-activated endonuclease were essentially the same for both cell lines. The 73K phosphoprotein kinase was induced at a similar rate of activity, whether detected in solution or after immobilization on poly(I)·poly(C)-Sepharose. Our observations thus suggest that the induction of these two enzymatic activities are not sufficient for the anticellular activity of interferon.     

In situ localisation of beet necrotic yellow vein virus (BNYVV) in rootlets of susceptible and resistant beet plants

Summary Mechanisms of resistance to beet necrotic yellow vein virus (BNYVV) were studied by comparing the multiplication and distribution of BNYVV in root tissue of some beet accessions. Seedlings were infected either by soil containing resting spores ofPolymyxa betae with BNYVV, or by a viruliferous zoospore suspension. With both inoculation methods high virus concentrations were obtained in rootlets of the susceptible cultivar Regina. Using infested soil, low virus concentrations were found in the partially resistant cultivar Rima and in the resistant accessions Holly and WB42. When a zoospore suspension was used, similar virus concentrations occurred in Rima and Holly as in Regina, while a low virus concentration was found in WB42. By in situ localisation studies, using immunogold-silver labelling, virus was detected in Regina after infection by soil or a zoospore suspension, but it could only be detected in the resistant accessions after infection by a zoospore suspension. In rootlets of Regina, Rima and Holly, virus was found in the epidermis, cortex parenchyma, endodermis, and interstitial parenchyma, but in general not inside the vascular tissue. In WB42 the virus, occurring in small aggregates, seemed to be restricted to the epidermis and some cortex parenchyma cells. Comparing both the multiplication and distribution of BNYVV in rootlets of the accessions studied, it is concluded that the virus resistance mechanism in Rima and Holly is different from that in WB42.     

Osmoregulation of Hymenolepis microstoma

Summary The present report deals with a study of the osmoregulation of young Hymenolepis microstoma using the in vitro cultivation at different osmotic pressures: i.e. in eleven media with freezing point depressions ranging from 0.35 to 1.21° C. It has been shown that H. microstoma is able to develop optimally and equally well in media with freezing point depressions from 0.50 to 0.73° C. The worm seems to have a regulatory system operating successfully between these approximate limits. Media with lower or higher osmotic pressures do not cause death within the present experimental conditions but inhibit development gradually.It is concluded that, although cestodes are regarded as poikilosmotic, the present results with H. microstoma indicate that homoiosmotic properties might exist within a certain limited range of osmotic pressures.Supported by a N.A.T.O. grant.Encouragement by Prof. Dr. C. A. Hopkins is gratefully acknowledged.