Cytochemical characteristics of the axon membrane at nodes of Ranvier in resting, tetrodotoxin-blocked, and electrically stimulated peripheral nerves of the rat

To test whether intraaxonal ferric ion-ferrocyanide staining at nodes of Ranvier is influenced by functional state of the nodal membrane, the tibial nerves of Sprague-Dawley rats were subjected to one of the following experimental procedures prior to fixation and staining: General anesthesia to induce nerves at rest, tetrodotoxin blocking of nerve activity, and high-frequency (100 Hz) electrical stimulation. In all cases most but not all nodes were stained. No statistically significant differences were found either in the percentage of total stained nodes or in the percentage of stained nodes from large- and small-diameter fibers among the three conditions tested. An explanation is offered to account for the apparent discrepancy between these results and those from other studies involving related cytochemical markers of the nodal apparatus.

Mechanism of inactivation of hexokinase PII of Saccharomyces cerevisiae by D-xylose

The mechanism of inactivation of hexokinase PII of Saccharomyces cerevisiae by D-xylose was characterized. Inactivation was dependent on the presence of MgATP and was irreversible. Inactivation involved phosphorylation of the protein. Observation of the carbon catabolite repression of selected enzymes showed that invertase and maltase synthesis were not repressed when hexokinase PII was phosphorylated.

Somatostatin in the treatment of severe upper gastrointestinal bleeding: a multicentre controlled trial

To evaluate the effectiveness of somatostatin versus combined cimetidine and pirenzepine in the treatment of upper gastrointestinal (GI) bleeding of peptic origin, a multicentre controlled, prospective, randomized and double blind trial has been undertaken in 60 subjects. Strict selection criteria were followed. All subjects were diagnosed by endoscopy during the first 18 h after admission. Endoscopic stigmata of recent haemorrhage were also evaluated. Sixty-five per cent of the subjects presented with severe upper GI bleeding (blood pressure less than or equal to 100 mmHg, pulse rate greater than or equal to 110, haematocrit less than or equal to 30 per cent), and in 71.6 per cent stigmata were found. Thirty patients (Group 1) received a somatostatin infusion (250 micrograms/h continuously during 120 h) and 30 patients (Group 2) received cimetidine (200 mg IV every 4 h for 5 days) and pirenzepine (10 mg IV every 8 h for 5 days). Both groups were homogeneous for sex, age, backgrounds, bleeding source, grade of bleeding (moderate or severe) and presence or not of stigmata. Bleeding stopped in 27 subjects of Group 1 (90 per cent and in 20 subjects of Group 2 (66.67 per cent) (P less than 0.05, chi 2 test). The time until the bleeding stopped was significantly shorter in patients of group 1 (3.44 +/- 0.53 h) than in patients of group 2 (8.12 +/- 1.94 h) (P less than 0.05, Mann-Whitney U test). The number of blood units required for Group 1 (2.26 +/- 0.35) was significantly lower than the one required for Group 2 (3.90 +/- 0.51) (P less than 0.005, Wilcoxon test). Significant differences were not observed between the two groups regarding cross-over subjects, re-bleeding, surgery (P = 0.0635, Fisher's exact test) and hospital stay. The mortality of the trial was 5 per cent. There was no toxicity during somatostatin, cimetidine or pirenzepine infusion. In conclusion, somatostatin was more effective than cimetidine plus pirenzepine in the control of severe upper GI bleeding of peptic origin, with a lower interval time to stop bleeding and reduced transfusion requirements.

Differential sensitivities to glucose and galactose repression of gluconeogenic and respiratory enzymes from Saccharomyces cerevisiae

The synthesis of isocitrate lyase was induced by the presence of ethanol in the chemostat reaching a specific activity of 200 mU X mg-1 at this induced state. In glucose-limited, derepressed cells, 20 mU X mg-1 were detected and under repressed conditions isocitrate lyase activity was not detected. The sensitivity of gluconeogenic enzymes: cytoplasmic malate dehydrogenase; fructose 1,6-bisphosphatase and isocitrate lyase as well as the mitochondrial enzymes NADH dehydrogenase and succinate cytochrome c oxidase to glucose and galactose repression were studied in chemostat cultures. Our results show that galactose was less effective as a repressor than glucose. Malate dehydrogenase was completely inactivated by glucose, whereas galactose only produced a 78% decrease of specific activity. Fructose 1,6-bisphosphatase and isocitrate lyase were completely inactivated by both sugars but at different rate. Glucose produced an 85% decrease of specific activity of the mitochondrial enzymes whereas galactose only decrease an 67%.

Inhibition and inactivation of glucose-phosphorylating enzymes from Saccharomyces cerevisiae by D-xylose

Three glucose-phosphorylating enzymes were separated from cell-free extracts of Saccharomyces cerevisiae by hydroxylapatite chromatography. Variations in the amounts of these enzymes in cells growing on glucose and on ethanol showed that hexokinase PI was a constitutive enzyme, whereas synthesis of hexokinase PII and glucokinase were regulated by the carbon source used. Glucokinase proved to be a glucomannokinase with Km values of 0.04 mM for both glucose and mannose. D-Xylose produced an irreversible inactivation of the three glucose-phosphorylating enzymes depending on the presence or absence of ATP. Hexokinase PI inactivation required ATP, while hexokinase PII was inactivated by D-xylose without ATP in the reaction mixture. Glucokinase was protected by ATP from this inactivation. D-Xylose acted as a competitive inhibitor of hexokinase PI and glucokinase and as a non-competitive inhibitor of hexokinase PII.

Percutaneous transluminal angioplasty of stenotic ductus arteriosus

This article describes our in vitro experience of balloon angioplasty of the ductus arteriosus (DA) in three post mortem human specimens, as well as an in vivo dilatation of a stenotic DA. The in vitro histologic observations revealed disruption of the intima and areas of pathologically fragmented and disorganized fibers at the media, with integrity of the ductal wall in all three DA. These findings led us to attempt percutaneous transluminal angioplasty (PTA) of a stenotic DA in a 2.3-kg newborn infant with hypoplastic left heart syndrome in a very deteriorated clinical condition. A Rashkind septostomy was associated with PTA of the stenotic DA. Following this, the gradients across the DA and across the atrial septum disappeared and the ductal angiographic diameter increased. Although an improved clinical condition was observed during the following hours, he died 1 day after. At necropsy, we found integrity of the ductal wall with histological changes similar to that observed in vitro. We conclude that PTA of stenotic DA could represent an alternative for palliative treatment of DA-dependent congenital heart disease.

Epidemiology of rotaviruses in a cohort of 45 Guatamalan Mayan Indian children observed from birth to the age of three years

A cohort of 45 children was observed from birth to three years of age in their natural ecosystem to determine patterns of infection, morbidity, and growth. Data from enzyme-linked immunosorbent assay analysis for rotavirus of 5,891 extracts (kept frozen since 1964-1969) of weekly fecal specimens were compared against growth, morbidity, and specimen data files, permitting a retrospective description of the epidemiology of rotavirus infection in the cohort. Rotavirus infections were uncommon in the first months of life in intensively breast-fed infants. Infection increased with age to reach a maximal rate in the six- to 18-month age period. While there was a high incidence of diarrhea in the cohort, rotavirus was associated with only 10% of such episodes. The incidence of rotavirus infection was 1.2 episodes per child-year, and the incidence of rotavirus-associated diarrhea was 0.8 episodes per child-year. Serious outbreaks of rotavirus generally occurred from September through December, with as many as one-half of the children becoming infected. Repeated rotavirus infection was a common phenomenon.

[Fever of undetermined origin in a case of total correction of persistent truncus arteriosus with agenesis of the left pulmonary artery (author's transl)]

A 19 month-old girl diagnosed of truncus arteriosus with absence of the left pulmonary artery and severe truncal valve insufficiency underwent total correction. A non previously diagnosed severe mitral insufficiency required a new operation to implant a Bjork-Shiley supraanular mitral prosthesis. The postoperative period was hemodynamically normal, except for the presence of persistent fever of unexplained origin. The clinical picture was thought to be an infectious endocarditis due to the late appearance of an aortic prosthetic leak. Because of failure to medical treatment a reoperation was performed to replace aortic prosthesis. Patient died eight hours postoperatively. Autopsy revealed a correct surgical repair, absence of endocarditis and severe miliary disseminated tuberculosis. Authors consider of interest to present this case-report due to the rarity of: a) correction of truncus with a single pulmonary artery under two years of age; b) associated mitral insufficiency; c) the presence of tuberculosis, difficult differential diagnosis with infectious endocarditis in a patient with valvular prosthesis.

[Maternal lactation. I. Resistance of maternal milk to bacterial contamination]

Bacteriologic studies in hands, nipples and milk in 10 wet-nurses were done in order to establish regulation for the recollection of breast milk to be used in low -birth-weight infants. The same studies were done in the hands of 10 nurse-aids, that help in the recollection of breast milk. The results depicts that the breast milk has bacteriostatic and bactericidal properties enough to protect against contamination by germs of the mother's bacterial flora. It does not have the same property against germs that are not of their own flora: those of the nurse-aids's hands. The protection is such that is possible to maintain the breast milk at environmental temperature of 4 degrees C, for 72 hours, without having the developing of germs not isolated previously, and even with the disappearance of some strains present in the initial cultures.

The pituitary reserve in FSH and LH in amenorrheic and anovulatory women

The pituitary gonadotropic response of FSH and LH "reserve" was studied in ten normal women, twelve amenorrheic and two impuberal patients, as compared with six sterile women with anovulatory cycles. The method as the intravenous injection of 100 microgrs. of synthetic porcine LH-RH followed by the radioimmunologic estimation of FSH and LH in plasms, before and after 15, 30, 45, 60, 90 and 120 minutes. This method allows an accurate estimation of the capacity of the adenohypophysis to release gonadotropins, the so called gonadotropic reserve. There are observed four types fo gonadotropic response to the LH-RH injection. Anovulatory sterile women and prepuberal girls have a very similar pattern with normal or very decreased FSH reserve and marked diminution in LH levels. Primary amenorrhea due to ovarian failure presents basal high values of both gonadotropins and increased response to the LH-RH stimulation. In primary amenorrhea without ovarian failure and in secondary amenorrhea, the LH patterns were normal, but in some cases a slight decrease in the FSH curve was observed. The method is regarded as very useful in the diagnosipothalumus-Pituitary-Ovary) Axis.