Temperature and PMA affect different phases of exocytosis in bovine chromaffin cells

Amperometry was used to study secretory kinetics of single bovine chromaffin cells stimulated by transient depolarizations at different temperatures. The initial rate of release was moderately enhanced when the temperature was raised from 18 to 22 and 37 degrees C. Secretion increased drastically at a later period, 5-10 s after the initiation of stimulus. Interestingly, incubation of the cells with phorbol 12-myristate 13-acetate (PMA) clearly enhanced fast secretory components. In addition, the rate of secretion of the slower component recruited by prolonged depolarizations (t > 30 s) was unaffected at the range of temperatures normally used in secretory experiments (22-37 degrees C). A 'counting events' analysis of secretion, which avoids the influence of event charge changes, showed specific increases in a population of vesicles fusing between 7 and 12 s over the same range of temperatures, and a marked increase in vesicles fusing during the initial phase (1-5 s), of PMA-treated cell secretion. An analysis of temperature influence on transient components released by high sucrose, the secretion elicited by cell permeabilization with digitonin, and studies of the individual characteristics of amperometric events, allow us to conclude that an increase in the size of a secondary-released vesicle population is the main factor contributing to temperature-dependent enhancement of secretion, in clear contrast to the enhancement of fast releasable pools caused by phorbol esters.

Feeding infant piglets formula with long-chain polyunsaturated fatty acids as triacylglycerols or phospholipids influences the distribution of these fatty acids in plasma lipoprotein fractions

Several sources of long-chain polyunsaturated fatty acids (LCP) are currently available for infant formula supplementation. These oils differ in their fatty acid composition, the chemical form of the fatty acid esters [triacylglycerols (TG) or phospholipids (PL)] and presence of other lipid components. These differences may affect LCP absorption, distribution and metabolic fate after ingestion. The purpose of the present study was to evaluate the influence of different chemical forms of dietary LCP on the composition of plasma, plasma lipoproteins, liver and jejunum in infant piglets. Thirty pigs (5 d old) were bottle-fed different diets for 4 wk: a control diet (C), a diet containing LCP as TG from tuna and fungal oils (TF-TG) or a diet containing LCP as PL from egg yolk (E-PL). We measured lipid and fatty acid composition of plasma and lipoproteins, as well as lipid composition of liver and intestinal mucosa. The arachidonic and docosahexaenoic acids in HDL-PL were significantly higher in piglets fed the E-PL diet than in those fed the TF-TG diet. Opposite results were found in the LDL-PL diet. No significant differences were found between groups in TG or cholesterol concentrations of plasma or lipoproteins. Arachidonic acid in plasma PL and cholesteryl esters was significantly higher in the E-PL group than in the TF-TG group. The chemical form in which LCP esters are present in different dietary sources influences their distribution in plasma lipoproteins. This may be important for infant nutrition and suggests that not all LCP sources may be biologically equivalent.

[Prevalence of depressive disorders in consultation-liaison psychiatry]

INTRODUCTION

Depressive disorders are more frequently seen in medically ill patients, especially in those who are hospitalized, than in the general population. The aim of this study was to assess the magnitude of this problem in Spanish hospitals, determining the prevalence of depressive disorders in hospitalized patients with medical illnesses, as well as the sociodemographic and medical-psychiatric characteristics related with the development of depression in these patients.

METHODOLOGY

A transversal study was performed in 13 Spanish public hospitals with a sample of 1.003 patients selected from the list of patients registered in medical services at each hospital on November 6, 1995. Each patient was evaluated on psycho-social stress level as well as quality of life (Karnofsky scale). Following that, the Hospital Anxiety and Depression Scale was applied and all patients with a score >= 11 were evaluated by a psychiatrist. Data on psychiatric consultation of these patients were also recorded when conducted.

RESULTS

18.9% of patients hospitalized for medical illnesses showed depressive symptoms. The presence of depressive disorders was more often seen in women, patients unable to work, patients with psychiatric history, patients with previous psychopharmacological treatments, patients with high level of psychosocial stress and patients with a low quality of life. Psychiatric consultations were requested in just 13.7% of these patients.

CONCLUSION

A very high number of hospitalized patients require a psychiatric evaluation for depression, but this is not requested.

Plasma fatty-acid composition and antioxidant capacity in low birth-weight infants fed formula enriched with n-6 and n-3 long-chain polyunsaturated fatty acids from purified phospholipids

OBJECTIVE

To determine whether a formula containing n-6 and n-3 long-chain polyunsaturated fatty acids (LCP) from purified phospholipids increases the content of 20:4n-6 and 22:6n-3 of plasma lipids and modifies the plasma antioxidant capacity in low-birth-weight infants.

STUDY DESIGN

Seventeen infants were fed a conventional formula for low birth-weight infants (F), and 17 a formula containing n-6 and n-3 LCP from purified pig-brain phospholipids (LCP-F). Fourteen infants receiving human milk from a human milk bank were used as a reference (HM). Growth index were measured and blood samples were taken at entry and after 15 days and 30 days of feeding.

RESULTS

In infants fed LCP-F the levels of 22:6n-3 in total plasma lipids and in plasma phospholipids and triglycerides were higher than in infants fed F and closer to the levels of HM group throughout the study. Docosahexaenoic acid concentration in total plasma lipids was 3.46+/-0.19 mg/dl in infants fed LCP-F and 2.08+/-0.20 in infants fed F after 15 days of feeding (P<0.001), and 3.83+/-0.30 and 2.15+/-0.20 in infants fed LCP-F and F respectively, after 30 days of feeding (P<0.001). The concentration of 20:4n-6 in the LCP-F was significantly higher than in the F group at 15 and 30 days of feeding. Plasma antioxidant capacity did not differ significantly between the study groups.

CONCLUSION

Feeding low birth-weight infants a formula containing LCP phospholipids results in an increase of n-3 and n-6 LCP in plasma towards that of infants fed human milk.

[Factors associated with dental enamel defects in the first molar in a population of children]

OBJECTIVES

To assess factors related to defects in the tooth enamel of the first permanent molar. Factors studied include, pediatric assistance, hospital admittance, high and low respiratory illness, varicella, gastroenteritis, ear infections, urinary tract infections, and different pharmacological treatments.

DESIGN

A retrospective case control study.

PARTICIPANTS

Cases and controls were selected randomly from a pool of 1382 scholars born in years 1980, 1981 and 1982.

MEASUREMENTS AND MAIN RESULTS

The study was conducted in march and may of year 2000. Finally 48 cases and 148 controls were selected. A dental examination was conducted at 8 years of age using the WHO criteria. Defects in the tooth enamel were defined according to the FDI criteria. We've measured and compared the study variables along the first five years of live. The epidemiological association was quantified by means of the odds ratio (OR) an its 95% confidence interval (CI). In the first year of live we estimated for pediatric assistance an OR of 2.26 (95% CI 1.05-4.92); in the second year for Urinary Tract Infections (UTI) we obtained an OR of 25.27 (95% CI 2.98-562.2); in the third year for UTI an OR of 6.68 (95% CI 1.01-54.52); in the fourth year the OR for pneumonia was 13.45 (95% CI 1.36-324.5) and finally in the fifth year the significant OR were: 2.56 (95% CI 1.23-5.34) for ear infections, 2.28 (95% CI 1.03-5.03) for macrolides and OR of 2.20 (95% CI 1.08-4.50) for anticongestive medications.

CONCLUSIONS

UTI and pneumonia show a high association with the presence of defects in the tooth enamel. Other variables such as high frequency of pediatric assistance, hospital admittance, ear infections, varicella, and pharmacological treatments with macrolides, cefolosporines, anticongestive medications and lungs medications showed a weak association.

Macroscopic water deposits on polycrystalline gold measured by scanning force microscopy

Data of water adsorption on polycrystalline gold show the formation of a multilayer film of several nanometers with the increase of relative humidity. We have measured this adsorption process by scanning force microscopy in both dynamic and jumping modes. We find interesting differences in the adsorption of water on the terraces and at grain boundaries. Measurements of adhesion force are also reported.

Statistical analyses of influence of solar and geomagnetic activities on car accident events

Statistical analyses of the influence of Solar and geomagnetic activity, sector structure of the interplanetary magnetic field and galactic cosmic ray Forbush effects on car accident events in Poland for the period of 1990-1999 have been carried out. Using auto-correlation, cross-correlation, spectral analyses and superposition epochs methods it has been shown that there are separate periods when car accident events have direct correlation with Ap index of the geomagnetic activity, sector structure of the interplanetary magnetic field and Forbush decreases of galactic cosmic rays. Nevertheless, the single-valued direct correlation is not possible to reveal for the whole period of 1990-1999. Periodicity of 7 days and its second harmonic (3.5 days) has been reliably revealed in the car accident events data in Poland for the each year of the period 1990-1999. It is shown that the maximum car accident events take place in Poland on Friday and practically does not depend on the level of solar and geomagnetic activities.

Dietary gangliosides positively modulate the percentages of Th1 and Th2 lymphocyte subsets in small intestine of mice at weaning

We studied the influence of dietary gangliosides on the number of spontaneous cytokine-secreting cells from two intestinal lymphocyte populations: lamina propria lymphocytes and Peyer's patches lymphocytes in Balb/c mice for 28 days after weaning. Weanling mice were separated into two groups, designated as Control and BG. The Control group was fed with a semipurified diet without gangliosides and the BG group was fed with the semipurified diet supplemented with 47 mg/kg of a mixture of bovine brain gangliosides. Intestinal lymphocytes were isolated from mice killed at 3, 7, 14 and 28 days after weaning, and the percentages of spontaneous Th1 as well as Th2 cytokine-secreting lymphocytes were determined using the ELISPOT assay. The BG group animals showed an earlier development in the number of cytokine-secreting cells, which appeared one week later in Control animals. In addition, mice fed with the ganglioside-supplemented diet showed a significantly higher number of Th1 and Th2 cytokine-secreting lymphocytes than Control mice in lamina propria and Peyer's patches lymphocytes at the end of the experimental period (28 days). Our results suggest that dietary gangliosides influence the maturation process of the intestinal immune system that take place during weaning.

Nutritional regulation of nucleoside transporter expression in rat small intestine

BACKGROUND & AIMS

Concentrative nucleoside transporters CNT1 (pyrimidine preferring) and CNT2 (purine preferring) may be involved in the uptake of nucleoside-derived drugs used in antiviral and chemical therapies. The possibility that nucleoside carrier isoform expression is modulated by nutrient availability has been studied.

METHODS

CNT1 and CNT2 tissue distribution was determined by Western blot analysis. The effect of 48-hour starvation on CNT expression was then studied. Nucleoside transporter expression and uptake activity were measured in jejunal brush border plasma membrane vesicles from fed and starved rats. The expression of nucleoside transporters was later determined in a second model of nutrient deficiency: rats fed a purified diet with or without nucleotides for 10 days.

RESULTS

CNT1 and CNT2 nucleoside transporters were expressed in a wider variety of tissues than expected from messenger RNA distribution analysis. CNT1 was sensitive to nutrient availability in small intestine and, accordingly, jejunal brush border membrane vesicles from 48-hour-fasted rats showed increased expression of CNT1 and enhanced Na(+)-dependent thymidine and gemcitabine uptake. This effect was mimicked by feeding semipurified diets lacking nucleotides.

CONCLUSIONS

Substrate availability modulates nucleoside transporter expression (CNT1) in rat jejunum in vivo.

Serum transforming growth factor-beta1 levels increase in response to successful anti-inflammatory therapy in ulcerative colitis

OBJECTIVE

To investigate serum levels of transforming growth factor-beta1 and interferon-gamma in active ulcerative colitis and to assess changes during treatment.

METHODS

We prospectively evaluated serum from 25 patients with untreated active ulcerative colitis and 19 healthy controls. Disease activity score (DAI), serum transforming growth factor-beta1 and interferon-gamma levels were measured at baseline and after 7 days of conventional treatment. Disease activity score and transforming growth factor-beta1 were also assessed at 42 days.

RESULTS

Baseline transforming growth factor-beta1 levels were significantly higher in patients than in controls (P < 0.02). On the 7th day, transforming growth factor-beta1 levels increased only in patients who responded (P < 0. 01); variations in transforming growth factor-beta1 levels and disease activity score were inversely correlated (r=- 0.72, P < 0. 001). At day 42, serum transforming growth factor-beta1 decreased significantly compared with the 7th day (P < 0.05). While in controls, interferon-gamma was undetectable; untreated patients had higher, widely variable, levels. At day 7, responders had higher interferon-gamma values than unresponsive cases. Variations in interferon-gamma correlated moderately with changes in transforming growth factor-beta1 (r=0.53, P < 0.05). Cytokine response did not depend upon the type of treatment.

CONCLUSIONS

Both transforming growth factor-beta1 and interferon-gamma may play a role in the injury-repair process in active ulcerative colitis. Variations in circulating transforming growth factor-beta1 levels in the first week of treatment seem to be related to the therapeutic response.

Antihepatotoxic activity of Rosmarinus tomentosus in a model of acute hepatic damage induced by thioacetamide

R. tomentosus is a vegetal species closely related to the culinary rosemary (R. officinalis), a plant reported to contain antihepatotoxic agents. A dried ethanol extract of the aerial parts of Rosmarinus tomentosus (Lamiaceae) and its major fraction separated by column chromatography (fraction F19) were evaluated for antihepatotoxic activity in rats with acute liver damage induced by a single oral dose of thioacetamide. Silymarin was used as a reference antihepatotoxic substance. Pre-treatment with R. tomentosus ethanol extract, fraction F19 or silymarin significantly reduced the impact of thioacetamide toxicity on plasma protein and urea levels as well as on plasma aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and gamma-glutamyl transpeptidase activities compared with thioacetamide-treated animals (group T). Pre-treatment with R. tomentosus ethanol extract significantly reduced the impact of thioacetamide damage on alkaline phosphatase and gamma-glutamyl transpeptidase activities compared with group T. Silymarin administration significantly reduced alkaline phosphatase and gamma-glutamyl transpeptidase activities compared with group T. Fraction F19 administration reduced only alkaline phosphatase activity compared with group T. According to these data, R. tomentosus extract shows promising antihepatotoxic activity, suggesting the need to isolate the chemical principles responsible for this activity and to study this activity in a model of thioacetamide-induced cirrhosis.

Gestational age and origin of human milk influence total lipid and fatty acid contents

The human milk composition may be influenced by several factors, such as gestational age or genetic characteristics and dietary habits of different populations. To analyze the total lipid and fatty acid contents of human milk, we have conducted two studies, one on mothers who had delivered preterm and term newborns and another on mothers from two different sociocultural backgrounds (Spain and Panama). The total lipid content (g/100 g wet weight) was significantly higher in term (2.76 +/- 0.66; mean +/- SD) than in preterm mature milk (1.06 +/- 0.4). The relative amount of 18:1n-9 was significantly higher in preterm than in term milk for transitional and mature milk, whereas that for the colostrum followed the opposite trend. Concerning the comparison between milk from mothers born in different countries, the relative contents of each of the fatty acids 16:0, 16:1n-7, 18:2n-6, 18:3n-3, and 22:5n-3 were higher in Panamanian than in Spanish milk, whereas the mean percentages of saturated fatty acids < 14:0, of 16:1n-9, and of 18:1n-9 were higher in Spanish than in Panamanian milk. Statistically significant differences were found during the three periods of lactation considered for almost all the fatty acids mentioned above, especially for 18:1n-9 and 18:3n-3. Although the potential biological significance of the changes in oleic acid content between preterm and term milk remains unclear, differences in fatty acid content between Spanish and Panamanian milk reflect the different composition of the diet among women from these countries.

Potential use of spectral image analysis for the quantitative evaluation of estrogen receptors in breast cancer

Evaluation of estrogen receptor (ER) content is an important factor in the choice of therapy and prognosis of breast cancer patients. In this study, we demonstrate a new spectral image analysis technique for objective and quantitative evaluations of stained specimens. The SpectraCube system was used to analyze nuclear antigens in thirteen cases of breast cancer stained by the immunoperoxidase method with hematoxylin counterstain. Spectral imaging segregated the spectrum of diaminobenzidine (DAB) from the background color of hematoxylin and a spectral index was calculated. The spectral index essentially agreed with the pathologist's index (on a scale of 0 to 3) in seven out of the thirteen cases. A substantial number of ER positive pixels was detected in the two cases scored as 0 by the pathologist's index. In a test case scored as 1 by the pathologist's index we detected a significant number of pixels, representing 47% of the nuclei, with DAB-intensity values higher than the cut-off value of 1.2. These data suggest that spectral image analysis is a sensitive method providing intensive information with high reproducibility. Our spectral imaging method is highly flexible, enabling the user to define the spatial resolution of the analyzed specimen by choosing the number of pixels per one nucleus.

Modeling study of exocytosis in neuroendocrine cells: influence of the geometrical parameters

Exocytosis in neuroendocrine cells is a process triggered by Ca(2+). A Monte Carlo simulation of secretion has been developed which, together with the diffusion of calcium, buffered by endogenous and/or exogenously added chelators, also accounts for the dynamics of exocytosis for a pool of readily releasable vesicles. Different distributions of channels and vesicles (random or correlated) are studied. A local study of exocytosis is carried out by obtaining capacitance time courses for the different types of release-ready vesicle pools (correlated or not with Ca(2+) channels). Also, depending upon the kinetic constants for the exocytotic process, we study the levels of local Ca(2+) needed to trigger secretion. Our simulations show that a strong heterogeneity in the calcium concentrations at the different sites of exocytosis is a requirement for reproducing the experimentally observed biphasic response in chromaffin cells in situ (Voets, T., E. Neher, and T. Moser. 1999. Neuron. 23:607-615). Correlated nonuniform distributions of channels and vesicles and the existence of diffusion barriers are shown to quantitatively explain the experimental data on chromaffin cells in situ. The first description requires a deeply heterogeneous distribution, with vesicles attached to the channels or far from them, but never at middle distances. The second description is able to reproduce biphasic release even for uniformly (readily releasable) distributed vesicles. We quantify the degree of inhomogeneity in the distribution of vesicles and how porous the diffusion barriers should be to account for the observed biphasic response.

Chronic diarrhea impairs intestinal antioxidant defense system in rats at weaning

The aim of the present study was to evaluate the influence of severe protein-energy malnutrition on the antioxidant defense system in the small and large intestine in rats at weaning. Chronic diarrhea and the subsequent malnutrition were induced by oral intake of a lactose-enriched diet. Twenty rats were weaned at 21 days of age, and the control group was fed a semipurified synthetic diet for two weeks. The malnourished group was fed the same diet but carbohydrates were replaced by lactose, and they developed diarrhea one day after. Rats were killed, and macroscopic and histological features were analyzed, DNA content was measured, and alkaline phosphatase, myeloperoxidase, and gamma-glutamyltranspeptidase activities were determined to assess the degree of intestinal injury. Glutathione levels as well as the activities of intestinal glutathione transferase, glutathione reductase, total glutathione peroxidase, selenium-dependent glutathione peroxidase, superoxide dismutase, and catalase were measured to study the antioxidant defense system. Malnourished rats showed loss of body weight and an increase in length and weight in jejunum and ileum, while no significant changes were observed in colon. Epithelial cells showed fewer and shorter microvilli, larger mitochondria with low inner density and loss of cristae, dilated endoplasmic reticulum, and Golgi apparatus. The protein-to-DNA ratio was higher in the jejunum, ileum, and colon of malnourished rats. Glutathione levels decreased 40% in jejunum and 50% in colon of malnourished rats. A 40-50% decrease in the activity of all the enzymes of the antioxidant defense system was observed in the jejunum and ileum of malnourished rats, while only catalase and glutathione transferase activities decreased 50% in colon. These results suggest that early chronic diarrhea and severe protein-energy malnutrition impair the antioxidant defense system in both the small and large intestine, which may have a role in the pathogenesis and maintenance of the vicious circle of malabsorption-diarrhea-malnutrition in infancy.

High frequencies of telomeric associations, chromosome aberrations, and sister chromatid exchanges in ulcerative colitis

OBJECTIVE

Chromosome instability provides a predisposing background to malignancy, contributing to the crucial genetic changes in multistep carcinogenesis. The aim of this work was to analyze chromosome instability in patients with ulcerative colitis (UC) to achieve a better understanding of the increased risk for colorectal cancer.

METHODS

Peripheral blood lymphocyte cultures from 20 untreated UC patients and 24 controls were used to study chromosome instability by assessing telomeric associations (TAS), chromosome aberrations (CA), and sister chromatid exchanges (SCE).

RESULTS

Mean frequencies of TAS and CA were significantly increased in UC patients compared to controls (p < 0.001). Chromosomes 10, 11, 21, 16, and 19 were the most frequently involved in TAS. A total of 104 CA clustered in 66 breakpoints could be exactly localized. Seven nonrandom bands significantly affected in UC patients were found (p < 0.004), showing a significant correlation with the location of cancer breakpoints (p < 0.003), particularly with colorectal carcinoma rearrangements. SCE analysis showed higher levels in patients compared to controls (p < 0.006), but no differences were observed in cell cycle kinetics.

CONCLUSIONS

Our results demonstrate the presence of an unstable genome in UC patients that could be related to the cancer development observed in this disease.

[Aetiology and bacterial resistance in urinary infections of outpatients]

BACKGROUND

Knowledge of the etiological agents of infections of the urinary tract and of the map of the antimicrobial sensitivity of each geographic zone is a practice recommended for improving the use of antibiotics and for facilitating the choice of empirical treatment. The aim of this study is to provide up-to-date information on the pathogen flora of outpatients urinary infections in our health area and their sensitivity to antimicrobials, based on the urinary cultivations carried out in the Microbiology laboratory of the Solchaga Outpatient Surgery during the last four years.

MATERIAL AND METHODS

Between 1996 and 1999, we carried out 92,816 urinary cultivations of outpatients. The urine specimens were sown on plaques with chocolate agar and MacKonkey agar with calibrated loop. The antibiogram was carried out using the Kirby-Bauer method.

RESULTS

The percentage of positive urinary cultivations was 17%. Gram-negative bacilli represented 88.9% of the isolations, Gram-positive cocci 11% and yeasts 0.1%. Escherichia coli was the most frequently isolated germ (71%). The sensitivity studies show that amoxycillin-clavulanic acid, first generation cephalosporins and fosfomycin maintain a sensitivity above 80%.

CONCLUSIONS

Up-to-date knowledge of the most common pathogen flora and their sensitivity to antimicrobials makes it possible for a more suitable selection to be made of the antibiotic treatment when the sensitivity pattern of the responsible germ is unavailable. In the light of the results we can conclude that amoxycillin-clavulanic acid, first generation cephalosporins and fosfomycin show a good activity in vitro, and should be considered as empirical treatments for infections of the urinary tract.

Experimental ulcerative colitis impairs antioxidant defense system in rat intestine

Increasing attention has been given recently to the role of free radicals in the pathogenesis of ulcerative colitis, since the inflamed intestine is exposed to oxidative stress generated by infiltrating macrophages and neutrophils within the lamina propia. The overall goal of this study was to evaluate whether experimental ulcerative colitis induces significant changes in the antioxidant defense system in an experimental model induced by the intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid. Twenty rats were treated with 80 mg/kg body weight of trinitrobenzenesulfonic acid and 20 with the same volume of 0.9% NaCl. Rats were killed at one and two weeks after treatment to evaluate colon damage by light and electron transmission microscopy. The degree of tissue injury and inflammation was determined by measuring alkaline phosphatase, gamma-glutamyltranspeptidase, and myeloperoxidase activities and prostaglandin E2 and leukotriene B4. Glutathione levels and the activity of the enzymes of the antioxidant defense system were determined. Enzymatic markers of colon injury showed higher activities in rats with ulcerative colitis. Concentrations of prostaglandin E2 and leukotriene B4 were higher in the groups treated for one week with trinitrobenzenesulfonic acid and markers decreased after two weeks of treatment. All antioxidant enzyme activities were higher at one and two weeks after treatment; however, a significant decrease in total glutathione content was also observed. In conclusion, ulcerative colitis induced by trinitrobenzenesulfonic acid damages the intestinal mucosa and is accompanied by a shift in the antioxidant enzyme activities, and low levels of glutathione. This deficiency in glutathione could be a target for new therapies to treat ulcerative colitis.

The F-actin cytoskeleton modulates slow secretory components rather than readily releasable vesicle pools in bovine chromaffin cells

Adrenal chromaffin cells were used to test the role of the peripheral cytoskeleton of F-actin in controlling different vesicle pools. Phorbol 12-myristate 13-acetate and calyculin A, two substances affecting phosphorylation-dephosphorylation cycles, produced different degrees of F-actin reorganization, inducing the partial and the almost total disassembly of this structure, respectively, as visualized using rhodamine-phalloidin staining. Consequently, electron microscopy studies revealed the higher efficiency of calyculin-A over phorbol 12-myristate 13-acetate in promoting vesicle access to the plasmalemma boundary. Surprisingly, only the phorbol ester enhanced fast kinetics and the population of rapidly releasable vesicle pools as studied by single-cell amperometry, whereas both agents, as well as the F-actin severing compound, Latrunculin A, promoted an increase in the population of vesicles recruited in response to prolonged or repetitive stimulations. Taken together, our data support the notion that the F-actin peripheral barrier controls primary granule recruitment from reserve vesicle pools, whereas the phorbol ester effect on the rapidly releasable pools might be related to the alteration of late secretory stage through protein kinase C-dependent phosphorylation of an unidentified target.

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.

[Decompression sickness in divers treated at the Israel Naval Medical Institute between the years 1992 to 1997]

Clinical characteristics of 125 divers treated for decompression sickness (DCS) in the hyperbaric multiplace chambers of this Institute during 1992-1997 were analyzed retrospectively. In 62 (51%) the diagnosis was DCS Type I (joint pain or skin involvement) and in 60 (49%) DCS Type II (neurological, inner ear or pulmonary disease). Risk factors for the evolution of DCS were depth and duration of the dives involving accidents, violation of recommendations of the decompression tables, and repeated dives. Results were available for 112 of the 125 patients. 54 of them (48%) recovered completely, and another 54 recovered partially; 4 did not respond to treatment. Inner ear DCS was less responsive to hyperbaric oxygen treatment (p = 0.0001). There was significant improvement of neurological function in those with severe neurological injury (p = 0.0001). Rapid diagnosis and transportation of divers with DCS to a hyperbaric chamber is of crucial importance.

Engineering pancreatic islets

Pancreatic islets are neuroendocrine organs that control blood glucose homeostasis. The precise interplay of a heterogeneous group of cell populations (beta, alpha, delta and PP cells) results in the fine-tuned release of counterbalanced hormones (insulin, glucagon, somatostatin and pancreatic polypeptide respectively). Under the premises of detailed knowledge of the physiological basis underlying this behaviour, two lines of investigation might be inferred: generating computational and operational models to explain and predict this behaviour and engineering islet cells to reconstruct pancreatic endocrine function. Whilst the former is being fuelled by new computational strategies, giving biophysicists the possibility of modelling a system in which new "emergent" properties appear, the latter is benefiting from the useful tools and strategic knowledge achieved by molecular, cell and developmental biologists. This includes using tumour cell lines, engineering islet cell precursors, knowledge of the mechanisms of differentiation, regeneration and growth and, finally, therapeutic cloning of human tissues. Gaining deep physiological understanding of the basis governing these processes is instrumental for engineering new pancreatic islets.