Internalization of extraintestinal Escherichia coli O18 strains by epithelial cells is modulated by EGF, insulin, and effectors of transmembrane signal transduction

Adhesion to and internalization into host cells is an essential step in the pathogenesis of various bacterial infections. Here we investigated the effects of growth factors on the internalization of Escherichia coli O18 strains isolated from patients with urinary tract infection (UTI) by human epithelial cells. A dramatic increase in the uptake of Escherichia coli was observed after treatment of epithelial cells with epidermal growth factor (EGF) and to a lower extent with insulin. EGF-dependent internalization can be suppressed by tyrosine kinase inhibitors suggesting an involvement of the receptor tyrosine kinases in the regulation of the endocytotic process. Inhibitors of phospholipase A2, lipoxygenase, and cyclooxygenase significantly decreased internalization of bacteria induced by EGF. Finally, the specific inhibitor of PI 3-kinases Wortmannin was shown to suppress completely the EGF-independent internalization. The data of this analysis indicate the involvement of several signaling paths in bacterial internalization of uropathogenic Escherichia coli O18 strains and contribute to the comprehension of the pathogenesis of recurrent UTI.     

Glucose-6-phosphate dehydrogenase activity in monolayer cultures of thyroid epithelial cells: TSH and inhibition of nitrogen oxide synthase affect the enzyme activity and the oxygen sensitivity of the histochemical assay

The objective was to investigate glucose-6-phosphate dehydrogenase (G6PD) activity in monolayer cultures of thyroid epithelial cells and to examine whether inhibition of nitric oxide synthase affects activity of G6PD or oxygen sensitivity of the assay. Primary cultures without TSH addition prior to experiments demonstrated a TSH-dependent increase in G6PD activity. G6PD activity was higher in F12 medium than in a serum-free physiological medium. Secondary cultures grown in F12 medium demonstrated a diminished activity of G6PD and a lack of response to TSH. In the serum-free physiological medium, G6PD activity was comparable to that found in primary cultures and a response to high concentrations of TSH was maintained. In primary cultures grown in F12 medium devoid of TSH, G6PD activity decreased dose-dependently when nitric oxide synthase activity was inhibited. The oxygen sensitivity of the assay was comparable to that reported previously in malignant cells and correlated with the activity of G6PD in primary cultures. We suggest that thyroid epithelial cells may be an appropriate system to investigate oxygen sensitivity of the G6PD assay as the cells demonstrate a reduced oxygen sensitivity which can be influenced by culture conditions.     

Cultures of human fetal pancreatic islet cells

Cultures of islets cells were obtained from the cadaveric pancreas of 16–25-week human fetuses. During culture two waves of mitotic activity were observed. An increase in the insulin concentration in the culture medium took place after a wave of mitotic activity.Department of Artificial Organs and Assisted Circulation, Laboratory of Pathomorphology, Scientific-Research Institute of Transplantation and Artificial Organs, Ministry of Health of the USSR. Laboratory of Biological Standardization of Hormones, Institute of Experimental Endocrinology and Hormone Chemistry, Academy of Medical Sciences of the USSR. Maternity Home No. 26, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 8, pp. 202–204, August, 1979.     

Effect of endurance and sprint exercise on the sensitivity of glucose metabolism to insulin in the epitrochlearis muscle of sedentary and trained rats

Summary The effects of two types of acute exercise (1 h treadmill running at 20 m· min^–1, or 6 × 10-s periods at 43 m · min^–1, 0° inclination), as well as two training regimes (endurance and sprint) on the sensitivity of epitrochlearis muscle [fast twitch (FT) fibres] to insulin were measured in vitro in rats. The hormone concentration in the incubation medium producing the half maximal stimulation of lactate (la) production and glycogen synthesis was determined and used as an index of the muscle insulin sensitivity. A single period of moderate endurance as well as the sprint-type exercise increased the sensitivity of la production to insulin although the rate of la production enhanced markedly only after sprint exercise at 10 and 100 U· ml^–1 of insulin. These effects persisted for up to 2 h after the termination of exercise. Both types of exercise significantly decreased the muscle glycogen content, causing a moderate enhancement in the insulin-stimulated rates of glycogen synthesis in vitro for up to 2 h after exercise. However, a significant increase in the sensitivity of this process to insulin was found only in the muscle removed 0.25 h after the sprint effort. Training of the sprint and endurance types increased insulin-stimulated rates of glycolysis 24 h after the last period of exercise. The sensitivity of this process to insulin was also increased at this instant. Both types of training increased the basal and maximal rates of glycogen snythesis, as well as the sensitivity of this process to insulin at the 24^th following the last training session. It was concluded that in the epitrochlearis muscle, containing mainly FT fibres, both moderate and intensive exercise (acute and repeated) were effective in increasing sensitivity of glucose utilization to insulin. Thus, the response in this muscle type to increased physical activity differs from that reported previously in the soleus muscle, representing the slow-twitch, oxidative fibres in which sprint exercise did not produce any changes in the muscle insulin sensitivity.     

Large Family With Maturity-Onset Diabetes of the Young and a Novel V121I Mutation in HNF4A

Maturity-onset diabetes of the young (MODY) is a subtype of early-onset diabetes mellitus which is characterized by autosomal dominant inheritance. Several genes are known to induce MODY : HNF4A/MODY1, GCK/MODY2, TCF1/MODY3, IPF1/MODY4, TCF2/MODY5 and NEUROD1/MODY6. We studied a Swiss family with 13 diabetic patients over 3 generations. The average age at diagnosis was 35 +/- 15 years (7 subjects before 30). In addition, 2 individuals had an abnormal oral glucose tolerance. The mutation present in this family was located in the DNA binding domain of HNF4A, a strongly conserved region across almost all species, and segregated in all the MODY patients. Identification of this missense mutation allowed for presymptomatic diagnosis in the younger generations and will improve medical follow-up of the predisposed individuals.     

Cough provocation with capsaicin is an objective way to test sensory hyperreactivity in patients with asthma-like symptoms

BACKGROUND: A group of patients with asthma-like symptoms and sensitivity to chemical irritants, but without bronchial obstruction, has been found among subjects referred for suspected asthma. They have no well-defined diagnosis, and no objective diagnostic method has previously been available. These patients are more sensitive to inhaled capsaicin than are patients with asthma or healthy controls. The aim was to study cough and other capsaicin-induced symptoms and to test the effect of a drug (lidocaine) that inhibits nerve transmission in sensory nerves. METHODS: Twelve patients were provoked with three different concentrations of inhaled capsaicin solutions in a randomized, double-blind order. They all had asthma-like symptoms and were sensitive to chemical irritants, but had no IgE-mediated allergy or demonstrable bronchial obstruction. Before the provocations, the patients inhaled lidocaine or placebo (saline), also in a double-blind, randomized order. The results were expressed as the number of coughs and scores of various symptoms. RESULTS: The patients reacted in a dose-dependent way with cough, airway, and eye symptoms, which were significantly reduced after preinhalation of lidocaine. CONCLUSIONS: A drug that inhibits transmission in sensory nerves successfully blocked the number of coughs and other symptoms provoked by inhalation of capsaicin. This indicates that the mechanisms underlying chemical sensitivity in these patients may originate in the sensory nervous system, and we call this condition "sensory hyperreactivity".     

Factors modulating the sensitivity of the relaxation to the loading conditions in rat cardiac muscle

The load sensitivity of the relaxation phase was studied in rat papillary muscle, with isotonic afterloaded contractions and stretches applied after the peak of isometric twitches.The tension decay occurred earlier in isotonic than in isometric contractions. When a central region of the preparation was marked with small stainless steel pins, a lengthening of this region could be shown during relaxation of isometric (fixed end) contractions. This lengthening was earlier and faster in isotonic afterloaded contractions. Therefore the sensitivity of relaxation to load or length changes could be described in the context of the general mechanism of relaxation which takes into account the non uniform behaviour of the muscle and the internal movement during contractions.Interventions which decelerate the activation decay rate had different effects on the load dependence of relaxation. Caffeine addition and substitution of strontium for calcium abolished the load sensitivity while a temperature reduction had no influence on it.     

Plasma insulin and lipid levels in untreated obstructive sleep apnoea and snoring; their comparison with matched controls and response to treatment

SUMMARY  Obstructive sleep apnoea (OSA), and snoring are associated with coronary heart disease. To assess whether OSA or snoring may contribute to this by raising fasting lipid or insulin levels, venous fasting total cholesterol, triglyceride, very-low-density lipoprotein, low-density lipoprotein, high-density lipoprotein, and insulin were measured in 15 untreated OSA patients and 18 snorers. Each of these subjects was individually matched to a control of the same sex, age ± 10%, body index ± 15%, smoking and drinking habits. This produced study groups which did not differ significantly by any of these criteria. Fasting venous blood samples were collected at 06.30 hours following polysomnography, and analysed blind of the subjects respiratory status. The OSA patients were then treated with nasal continuous positive airway pressure. In 10 of these subjects lipid and insulin levels were repeated after more than three months treatment. Lipid and insulin levels were also remeasured in the controls matched to these 10 subjects. The end points were compared with paired t -tests.
There was no difference in any of the end points when the untreated OSA patients and the snorers were compared to their matched controls ( P >0.25 for all comparisons), and none of the indices changed when OSA was corrected with nasal continuous positive airway pressure ( P > 0.25 for all comparisons).
Patients with obstructive sleep apnoea or snoring do not have significant fasting hyperlipidaemia or hyperinsulinaemia when compared to carefully matched controls. These factors are therefore unlikely to be the cause of the excess cardiovascular mortality experienced by this patient group.