Ultrastructural changes in pancreatic beta cells treated with NGF and dbcAMP.

Nerve growth factor (NGF) induces morphological and physiological changes in cultured pancreatic beta-cells, including the extension of neurite-like processes. This latter effect is potentiated by dibutyryl cAMP (dbcAMP). beta-cells cultured under these conditions maintain their immunoreactivity to insulin and gamma-amino-butyric acid (GABA). NGF, dbcAMP, and high glucose concentrations also increase the expression of the GABA-synthesizing enzyme glutamic acid decarboxylase-65 in cultured beta-cells. The aim of this work was to study the effect of NGF alone or in combination with dbcAMP on pancreatic beta-cell ultrastructural morphology, after 10 days in culture. We used light microscopy, scanning electron microscopy, and transmission electron microscopy to analyze the modifications in cell surface and neurite-like projections. Morphometric analysis showed that NGF and/or dbcAMP treatment substantially increased the insulin and GABA content in granules and rough endoplasmic reticulum. Given that pancreatic beta-cells express NGF receptors and that NGF is synthesized and secreted by beta-cells, these results further suggest that NGF could have trophic actions on pancreatic hormone synthesis and/or storage.

Nerve growth factor increases insulin secretion and barium current in pancreatic beta-cells.

We analyzed the effect of a brief exposure to nerve growth factor (NGF) on insulin secretion and macroscopic barium currents of single adult rat pancreatic beta-cells. After a 1-h exposure to NGF (50 ng/ml), single beta-cells show a 2.5-fold increase in the insulin secretion index in 5.6 mmol/l glucose and a nearly twofold increase in 15.6 mmol/l glucose compared with control cells. We have recently demonstrated that pancreatic beta-cells synthesize and secrete NGF. We analyzed the effect of endogenous NGF on insulin secretion by incubating islet cells in the presence of an anti-NGF monoclonal antibody for 1 h in different glucose concentrations. Although the basal insulin secretion index (5.6 mmol/l glucose) is not affected, glucose-stimulated insulin secretion (15.6 mmol/l glucose) is decreased by 41% in the presence of the antibody. This effect is mediated by the activation of the NGF receptor TrkA because the specific inhibitor of Trk phosphorylation K252a also blocks NGF-induced increase in insulin secretion, both in the presence and absence of exogenous NGF. Using the whole-cell variation of the patch-clamp technique, we found that cells exposed to NGF for 5 min exhibit a 32% increase in the average barium current density. These results suggest that the effects of NGF on insulin secretion are partially mediated by an increase in calcium current through Ca channels. These results further suggest that NGF plays an important autoregulatory role in pancreatic beta-cell function. Two targets of short-term NGF-modulation are insulin secretion and calcium-channel activity.

Nerve and fibroblast growth factors as modulators of pancreatic beta cell plasticity and insulin secretion.

Trophic factors such as nerve and fibroblast growth factors are important modulators of beta cell physiology. These two factors induce the extension of neurite-like processes in primary cultures of adult rat beta cells. Moreover, both NGF and FGF enhance glucose-induced insulin secretion. Since beta cells synthesize NGF and pancreatic islet cells produce FGFs, it is possible that autocrine/paracrine interactions may be major regulators of insulin secretion, and impairment of these interactions could lead to pathological states such as diabetes mellitus.

[Pneumopathy in patients surgically treated for type III esophageal atresia]. / Neumopatía en pacientes intervenidos de atresia de esófago tipo III.

UNLABELLED: Patients following esophageal atresia with tracheoesophageal fistula (EA-TEF) treatment have several long-term respiratory complications during infancy. They are associated with esophageal dismotility and gastroesophageal reflux (GER) as well as lung dysplasia. MATERIAL AND METHODS: Ten patients were evaluated as follow: 1. Review of medical record. 2. An annual interview was performed concerning respiratory and digestive symptoms. 3. Phmetric score and radiologic studies of the digestive tract. 4. Functional respiratory test. 5. Update symptoms. RESULTS: Mean follow-up was 7.3 +/- 4.45 years (8 months-15 years). Seven cases (70%) had respiratory distress during the first postoperative year. Two of them had middle GER, performing a Nissen procedure in another patient with severe GER. Spirometry was underwent in 6 cases, showing a restrictive pattern in three. CONCLUSION: Respiratory distress were common during the first postoperative year (70% of cases in our serie) but only 25% were GER related. Pulmonary function test can be performed in long-term evolution of patients following operation for EA-TEF in order to have early treatment for respiratory complications.

Heterogeneity in glutamic acid decarboxylase expression among single rat pancreatic beta cells.

AIMS/HYPOTHESIS: An isoform of glutamic acid decarboxylase, (GAD)65 has been identified as a pancreatic beta-cell autoantigen in Type I (insulin dependent) diabetes mellitus. We investigated the expression of GAD isoforms among single rat beta cells in culture, under different conditions and the correlation between GAD65 expression and insulin secretion-rate. RESULTS: Independent of culture conditions, 100 % of fresh and cultured beta cells express GAD67. In contrast, considerable heterogeneity in GAD65 expression among single beta cells was observed. After 2 days in culture in 2.6 mmol/l glucose, only 24 % of the beta cells express GAD65. This percentage increases to 39 % in 5.6 mmol/l glucose and to 54 % and 56 % in 11.6 mmol/l and 20.6 mmol/l glucose, respectively. Moreover, reducing glucose concentration from 11.6 to 2.5 mmol/l for 2 days, reduces GAD65 expression by nearly 30 %. After 11 days in culture with 11.6 mmol/l glucose, 50 % of beta cells continue expressing GAD65, this percentage is further increased to nearly 75 % by including either nerve growth factor or dibutyryl cyclic AMP or both in the culture medium. When beta cells are challenged for 1 h with 20.6 mmol/l glucose, 67 % respond forming insulin-immunoplaques. More than two-thirds of insulin-secretors are GAD65-positive, in contrast to only 11 % of the non-secreting cells. Moreover, 87 % of beta cells that have a high insulin secretory rate express GAD65. CONCLUSION/INTERPRETATION: These results show that the most active beta cells, which secrete more insulin, also express GAD65 and that manipulating extracellular glucose may modify the expression of the enzyme and possibly the autoimmune attack in Type I diabetes.

[A reliability analysis of FACES III (the version in Spanish). Family Adaptability and Cohesion Evaluation Scales]. / Análisis de la confiabilidad de FACES III (versión en español).

OBJECTIVE: To determine through five methods (Cronbach's alpha, split, Guttman method, parallel and strict parallel) the confidence coefficient of FACES III, instrument validated on spanish version, and to evaluate it's consistency with these five statistical methods. DESIGN: Descriptive, cross-sectional. SETTING: Tlalpan Area, south of Federal District, México, divided into geo-statistical zones. PATIENTS AND OTHER PARTICIPANTS: A randomised sample of 270 dwellings with proportional coverage, based on 17,895 ordinary dwellings of the area. INTERVENTION: Domicile survey using FACES III (Family Adaptability and Cohesion Evaluation Scales); April-May 1995. MEASUREMENTS AND MAIN RESULTS: The confidence coefficient of FACES III spanish version was calculated using no standardised Cronbach's Alpha = 0.69; split I = 0.73 and split II = 0.66; Guttman method = 0.75; parallel = 0.69 and strict parallel = 0.53. CONCLUSIONS: Cronbach's coefficient demonstrated more advantages than the other statistical methods in relation with the ordinal measurement scale of FACES III. We suggest to take into consideration three important aspects for the correct confidence analysis of this kind of instruments: Variance analysis depending on the scale of items (F test, Friedman or Cochran) Inter-items interactions analysis (nonadditivity) and the use of the balance value as purge element of error' source. Analysis of Tukey estimate, coefficient of concordance (W) and Hotelling's T squared. It's necessary the evaluation and analysis of this aspects before the report of confidence's coefficient values whose can have hidden skew.

[Prospective and comparative study between cefuroxime, ceftriaxone and amoxicillin-clavulanic acid in the treatment of community-acquired pneumonia]. / Estudio prospectivo y comparativo entre cefuroxima, ceftriaxona y amoxicilia-clavulánico en el tratamiento de la neumonía adquirida en la comunidad.

Among community-acquired infections, pneumonia is still a large health problem which is of great interest mainly due its high mortality and morbidity. From 1991 to 1997, 409 patients who had been diagnosed with community-acquired pneumonia and had been admitted to the internal medicine service of a university hospital were prospectively studied. The patients were classified into three groups according to the random antibiotic treatment they had received (ceftriaxone, cefuroxime or amoxicillin-clavulanic acid). The initial characteristics of the patients with regard to epidemiology, clinical description and critical situation were similar in all the groups studied. A total of 36.9% of the cases were documented microbiologically, with the most frequently isolated pathogens being Streptococcus pneumoniae and Haemophilus influenzae. The recovery rate was 92.2% and three patients had a recurrence of pneumonia. Global mortality was 5.8%. No statistically significant differences were found in the evolution of patients treated with cefuroxime, ceftriaxone or amoxicillin-clavulanic acid, with the latter representing an empirical treatment of choice for community-acquired pneumonia.

Pancreatic beta cells synthesize and secrete nerve growth factor.

Differentiation and function of pancreatic beta cells are regulated by a variety of hormones and growth factors, including nerve growth factor (NGF). Whether this is an endocrine or autocrine/paracrine role for NGF is not known. We demonstrate that NGF is produced and secreted by adult rat pancreatic beta cells. NGF secretion is increased in response to elevated glucose or potassium, but decreased in response to dibutyryl cAMP. Moreover, steady-state levels of NGF mRNA are down-regulated by dibutyryl cAMP, which is opposite to the effect of cAMP on insulin release. NGF-stimulated changes in morphology and function are mediated by high-affinity Trk A receptors in other mammalian cells. Trk A receptors are present in beta cells and steady-state levels of Trk A mRNA are modulated by NGF and dibutyryl cAMP. Taken together, these findings suggest endocrine and autocrine roles for pancreatic beta-cell NGF, which, in turn, could be related to the pathogenesis of diabetes mellitus where serum NGF levels are diminished.

Prospective study of epidemiology and prognostic factors in community-acquired pneumonia.

Of 342 patients with community-acquired pneumonia, 100 were diagnosed etiologically. In these patients, disease epidemiology, prognostic factors, and influence of antibiotic treatment were analyzed prospectively. Fifty-two patients were treated with a broad-spectrum antibiotic (ceftriaxone), and 48 received a medium-spectrum antibiotic (cefuroxime); some patients in each group also received erythromycin. Streptococcus pneumoniae was the most frequently isolated microorganism (43%), followed by Chlamydia pneumoniae (21%), Haemophilus influenzae (19%), and Mycoplasma pneumoniae (11%). Factors significantly associated with increased mortality were initially critical or poor clinical condition, involvement of two or more lobules, and complications. Prior administration of antibiotics was predictive of penicillin and erythromycin resistance in Streptococcus pneumoniae, but had no effect on the course of the disease. Eight patients died, 89 were cured, and three had recurrences; there was no significant difference in outcome between treatment groups, regardless of whether patients also received erythromycin. Increased knowledge of epidemiological, predictive, and prognostic factors can significantly improve early diagnosis of community-acquired pneumonia and facilitate the choice of appropriate antibiotic treatment, thereby helping to reduce morbidity and mortality.

Neuron-like phenotypic changes in pancreatic ß-cells induced by NGF, FGF, and dbcAMP.

We studied the effects of nerve growth factor (NGF), fibroblast growth factor (FGF), and dibutyryl-cAMP (dbcAMP) on rat pancreatic ß-cell morphology and of NGF and dbcAMP on insulin secretion. After 2 wk in culture, nearly 3% of ß-cells extended neurite-like processes spontaneously; when cells were treated with NGF, almost 30% of them extended processes. In the presence of dbcAMP, almost all ß-cells flattened, and the extension of neurite-like processes was more pronounced in fetal than in adult cells. The most prominent effect, regardless of age, was observed in cells treated with NGF and dbcAMP together, since the percentage of neurite-like bearing ß-cells increased to 50%. ß-cells cultured under these conditions maintained their immunoreactivity to insulin and nearly all ß-cells and their neurite-like processes were also positive to GABA, tubulin, tau protein, and N-CAM. FGF increased the percentage of adult ß-cells bearing neurite-like processes to 13%, and FGF and dbcAMP applied together to 40%. ß-cells treated with NGF and dbcAMP for 5 to 7 d preserved their capability to secrete the hormone in response to different extracellular glucose concentrations. Insulin secretion of dbcAMP-treated ß-cells was 2.5-fold higher than in control cells. NGF-treated cells were able to discriminate between different glucose concentrations, a property lost in control cells with time in culture.

[Clinical and anatomopathological study of 5 patients with vasculitis and anti-neutrophil cytoplasmic antibodies with cytoplasmatic pattern]. / Estudio clínico y anatomopatológico en cinco casos de vasculitis portadores de anticuerpos anticitoplasmáticos de neutrófilos con patrón citoplasmático.

We report five patients with vasculitis and antineutrophil cytoplasmic antibodies with cytoplasmatic pattern. All had severe upper and lower respiratory tract necrotizing lesions. Three had kidney failure due to rapidly progressive glomerulonephritis. The pathological study showed a crescentic glomerulonephritis, a chronic granulomatous inflammation in the lungs and in the nasal mucosa, an acute nonspecific inflammation or a chronic granulomatous inflammation and focal blood vessel fibrinoid necrosis. All patients with simultaneous involvement of lungs and kidneys had high titers of antineutrophil cytoplasmic antibodies. The nomenclature and classification of these diseases is discussed.

Comparison of germline mosaics of genes in the Polycomb group of Drosophila melanogaster.

The genes of the Polycomb group (PcG) repress the genes of the bithorax and Antennapedia complexes, among others. To observe a null phenotype for a PcG gene, one must remove its maternal as well as zygotic contribution to the embryo. Five members of the PcG group are compared here: Enhancer of Polycomb [E(Pc)], Additional sex combs (Asx), Posterior sex combs (Psc), Suppressor of zeste 2 [Su (z) 2] and Polycomblike (Pcl). The yeast recombinase (FLP) system was used to induce mitotic recombination in the maternal germline. Mutant embryos were analyzed by staining with antibodies against six target genes of the PcG. The loss of the maternal component leads to enhanced homeotic phenotypes and to unique patterns of misexpression. E(Pc) and Su(z) 2 mutations had only subtle effects on the target genes, even when the maternal contributions were removed. Asx and Pcl mutants show derepression of the targets only in specific cell types. Psc shows unusual effects on two of the targets, Ultrabithorax and abdominal-A. These results show that the PcG genes do not act only in a common complex or pathway; they must have some independent functions.

[Correlation between four-hour creatinine clearance and 51Cr-EDTA test]. / Correlación entre clearance de creatinina de 4 horas y la prueba de 51Cr-EDTA.

BACKGROUND: Creatinine clearance as a measure of glomerular filtration rate has several sources of error such as tubular creatinine secretion or faulty urine collections. On the other hand 51Cr-EDTA test is reliable and accurate, except in patients with edema, in whom the radioisotope equilibrium is retarded after injection. AIM: To validate a 4-hours creatinine clearance correlating it with 51Cr-EDTA test. METHODS: In 59 non insulin dependent diabetic patients without diabetic nephropathy, glomerular filtration rate was measured using one 50 microCi injection of 51Cr-EDTA and collecting blood samples for radioactivity measurement at 10, 30, 120 and 240 min. Simultaneously, creatinine clearance was measured using a 4 hours urine collection. RESULTS: The general correlation coefficient between both methods was 0.85 (p < 0.001). For glomerular filtration rates below 95 ml/min, the correlation coefficient was 0.8 (p < 0.001), for values between 95 and 127 ml/min, the correlation was 0.51 (p < 0.001) and for values over 127 ml/min the correlation was 0.8 (p < 0.001). The regression equation obtained was y = 1,2x + 13 where y was the glomerular filtration rate measured with 51Cr-EDTA and x the same value measured with creatinine clearance. CONCLUSIONS: The four hours creatinine clearance is a reliable method to estimate glomerular filtration rate.

Functional heterogeneity of single pancreatic beta-cells stimulated by L-leucine and the methyl ester of succinic or glutamic acid.

Single pancreatic beta-cells exposed to D-glucose in the absence or presence of L-leucine and to the amino acid in the absence or presence of either the monomethyl ester of succinic acid (SME) or the dimethyl ester of glutamic acid (GME) were examined in a reverse hemolytic plaque assay for insulin release. At a D-glucose concentration of 11.1 mM, plaque-forming cells amounted to 84.8 +/- 1.0% including 11.4 +/- 4.1% of cells forming large plaques. These percentages were not increased by the incorporation of L-leucine (5 mM) into the incubation medium despite the fact that the amino acid, when tested in the absence of D-glucose, caused sizeable secretory activity. When the secretory response evoked by L-leucine was increased by either SME (10 mM) or GME (3 mM), marked heterogeneity of individual beta-cells in terms of both the occurrence and magnitude of hemolytic plaques was again observed. These findings argue against the view that the heterogeneity in secretory behavior of isolated purified beta-cells can be accounted for solely by differences in hexose metabolism as conceivably attributable to individual variations in glucokinase activity.