Cytochemical examination of the compartments involved in the transcellular transport of horseradish peroxidase in rat hepatocytes

Horseradish peroxidase (HRP, 10 mg/100 g body weight) was intravenously injected into rats in order to investigate the nature of the compartments involved in the transcellular transport of the protein through hepatocytes into bile. Double cytochemistry for HRP and the marker enzymes for cytoplasmic organelles was used. HRP was shown to be taken up by hepatocytes via vesicles at the sinusoidal surface, some of which were positive for 5'-nucleotidase activity. HRP was then found in the smooth-surfaced vesicles and tubules which were negative in 5'-nucleotidase, glucose 6-phosphatase, thiamine pyrophosphatase and acid phosphatase activity, suggesting that the tubular structures are neither the endoplasmic reticulum, the Golgi apparatus nor lysosomes. Biochemical studies revealed that the lead procedures used for the double cytochemistry did not inhibit the peroxidatic activity of HRP, and conversely that HRP did not interfere with the marker enzyme activity. Such cytochemical observations seemed to be supported by the observation that administration of monensin (3.5 mg/100 g) and chloroquine (5 mg/100 g), which markedly altered the structure of the Golgi apparatus and lysosomes, respectively, slightly altered the biliary excretion of HRP but not to a significant extent.     

Hepatocidol toxicity of Listeria species

A novel rat hepatocidal test, based on morphological changes in monolayer culture and the percentage of lactate dehydrogenase (LDH) released into the medium after exposure to culture filtrates of Listeria spp. was used to determine listerial toxicity and pathogenicity. Primary cultures of rat hepatocytes exposed to brain heart infusion (BHI) culture filtrates from ATCC strains of Listeria monocytogenes and L. ivanovii, released 91-92% and 95% of LDH after 3 h and 18.5 h, respectively. Cultured monolayers changed from normal hepatocytes into nonviable round forms. Brain heart infusion broth and BHI culture filtrates of other Listeria spp. were nontoxic to hepatocytes. The rat hepatocidal test is a quantitative and rapid system for studying listerial toxicity and pathogenicity.     

In vivo study on medullary H(+)-sensitive neurons

Using the micro pressure ejection technique, we examined responses of medullary neurons with nonphasic discharges (164 units) to direct application of acidified mock cerebrospinal fluid (CSF, pH 6.85-7.05) in decerebrated spontaneously breathing cats. We found 16 H(+)-sensitive cells; they were excited promptly on application of approximately 500 pl of acidified mock CSF in the vicinity of the neuron under investigation, whereas they were unaffected by microejection of the control mock CSF (pH 7.25-7.60). Of the 16 H(+)-sensitive cells, 10 units were further found to be excited by transcapillary stimulation of the central chemoreceptors by using a method of intravertebral arterial injection of CO2-saturated saline. The discharges increased in a similar time course to that of ventilatory augmentation. Distributions of these 10 specific H(+)-sensitive cells were found in the vicinity of nucleus tractus solitarii as well as deep in the ventrolateral medulla. The present results suggest a possibility that pH-dependent central chemoreceptors, if any, would be located in two distinct medullary regions described in this study.     

Relation of smoking and alcohol and coffee consumption to active Helicobacter pylori infection: cross sectional study.

OBJECTIVE: To assess the relation of smoking and alcohol and coffee consumption to active Helicobacter pylori infection. DESIGN: Cross sectional study of patients attending a general practitioner. Active H pylori infection was measured by the 15C-urea breath test and detailed quantitative information on smoking and on alcohol and coffee consumption was obtained by a standardised self administered questionnaire. SETTING: One general practice in Germany. SUBJECTS: 447 patients aged 15-79 who had not had peptic ulcer disease or treatment for H pylori infection. MAIN OUTCOME MEASURES: Prevalence of H pylori infection according to smoking and alcohol and coffee consumption. RESULTS: Overall prevalence of infection was 21% (94/447). There was no significant relation between smoking and active H pylori infection. Alcohol consumption showed a negative dose-response relation and coffee consumption a positive dose-response relation with active infection. After adjustment for potential confounders, the odds ratios for patients who drank < or = 75 g and > 75 g of ethanol a week compared with non-drinkers were 0.90 (95% confidence interval 0.55 to 1.59) and 0.33 (0.16 to 0.68), respectively (P value for trend 0.005, assuming that 1 litre of beer and 0.51 of wine contain on average 50 g of ethanol in south Germany). Adjusted odds ratios for patients who drank < 3 cups and > or = 3 cups of coffee per day compared with those who did not drink coffee were 1.49 (0.71 to 3.12) and 2.49 (1.23 to 5.03), respectively (P value for trend 0.007). CONCLUSION: These results suggest a protective effect of alcohol consumption against active infection with H pylori and an opposite effect of coffee consumption.