bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of an Oral Fluid Immunoglobulin G ELISA for the Detection of Helicobacter pylori Infection in Children
Authors: Gilger M.A. , Tolia V. , Johnson A. , Rabinowitz S. , Jibaly R. , Elitsur Y. , Chong S. , Rosenberg A. , Gold B. , Rosenthal P. , Elkayam O. , Marchildon P. , Peacock J.
Published: March 2003

Background. Enzyme linked immunosorbent assay (ELISA) evaluation of oral fluid immunoglobulin G (IgG) antibodies to Helicobacter pylori is a unique approach for both epidemiological studies and the diagnosis of infection, especially in children. The use of oral fluid sampling to evaluate specific H. pylori IgG antibodies has advantages over serum, including reduced biohazard risk and noninvasive collection. Oral fluid sampling is fast and involves minimal patient discomfort. Since children facilitate transmission of H. pylori infection, a simple, accurate, noninvasive diagnostic test is necessary for large epidemiologic studies. The aim of our study was to evaluate a new oral fluid ELISA for detection of IgG antibodies to H. pylori in children.

Materials and methods. We compared this new oral fluid ELISA with the HM‐CAPTM serum ELISA and gastric biopsy histology using 779 oral fluid samples from children collected at 11 clinical sites across the United States. This cohort included 315 children symptomatic for abdominal pain and 464 asymptomatic. All samples were evaluated in a double blind manner. The oral fluid ELISA demonstrated a sensitivity of 76.2% and a specificity of 94.0% in children 2 months old to 201/2 years, as compared with the HM‐CAPTM serologic assay. The assay’s sensitivity improved to 81.3% in children aged 5 or greater and the specificity remained at 94.0%. When compared with gastric biopsy histology in the same age group, the oral fluid ELISA demonstrated a sensitivity of 71.7% and a specificity of 90.4%.

Results. This new oral fluid ELISA is moderately sensitive and offers a very specific method for detecting H. pylori infection in older children, but it is of little value in children under the age of 5 years.

Conclusions. Overall, we conclude that this oral fluid ELISA does not appear to be a helpful clinical tool for the diagnosis of H. pylori infection in children.
Central regulation of food intake in the neonatal chick
Authors: FURUSE Mitsuhiro
Published: March 2003

Regulating food intake is complicated in animals including domestic birds. Just after hatching, neonatal chicks find their food by themselves and they can control food intake, since domestic chicken belongs to the precocial type of avian species. Thus, domestic chickens have relatively well‐developed mechanisms of food‐intake control at hatching. While many aspects of food‐intake regulation in chickens appear similar to that in mammals, there are some responses that are unique to chickens. For instance, some neurotransmitters such as neuropeptide Y (NPY), orexin‐A, orexin‐B, motilin, melanin‐concentrating hormone (MCH), galanin, growth hormone releasing factor (GRF) and ghrelin stimulate feeding in mammals. Only NPY strongly stimulates food intake in birds similar to that observed in mammals; however, both orexins, motilin, MCH and galanin failed to alter food intake of the chick. Moreover, GRF and ghrelin suppressed feeding of chicks. On the other hand, cholecystokinin (CCK), gastrin, glucagon‐like peptide‐1 (GLP‐1), corticotropin‐releasing factor (CRF), histamine, α‐melanocyte stimulating hormone (α‐MSH), leptin and bombesin are known to suppress feeding in mammals. These responses are similar to those of mammals except for leptin. Therefore, the inhibitory mechanisms for feeding are well conserved in chicks.
In vitro effects of insulin on glucose and lipid metabolism in rat embryos
Authors: TSUJII Hirotada , NAKAMURA Yumi , HAMANO Koh‐ichi
Published: March 2003

Glucose is utilized for oxidation and synthesis of various lipids in cultured rat embryos. The present experiment examined the effect of insulin on the incorporation of glucose into lipid fractions in rat embryos in vitro. Embryos at the 2‐cell, 8‐cell and blastocyst stages were incubated for 5 h in hamster embryo culture medium (HECM)‐1 containing 14C‐glucose and 170 nmol/L insulin, or in HECM‐1 containing only 14C‐glucose, and the oxidation of glucose in these embryos was examined. In addition, the total lipids of blastocysts were separated by thin layer chromatography and the radioactivity of the separated lipid fractions was measured. Oxidation of glucose was significantly increased after insulin treatment compared with that without insulin treatment in 8‐cell embryos and blastocysts (P < 0.05), but not in 2‐cell embryos. Incorporation of glucose into lipids in blastocysts was significantly lowered by insulin treatment compared with that without insulin treatment (P < 0.05). Most of the radioactivity was recovered from triacylglycerols of blastocysts and the remaining radioactivity was found in other neutral lipids and phospholipids. We conclude that insulin accelerates the utilization for oxidation of glucose and inhibits the storage of triacylglycerols in rat blastocysts.
Mechanical stretch‐induced activation of skeletal muscle satellite cells is dependent on nitric oxide production in vitro
Authors: TATSUMI Ryuichi , HATTORI Akihito , ALLEN Ronald E. , IKEUCHI Yoshihide , ITO Tatsumi
Published: March 2003

Mechanical stretch induces activation of cultured quiescent satellite cells and the activation response is owing to rapid release of hepatocyte growth factor (HGF) from its extracellular association with satellite cells and its subsequent presentation to the c‐met receptor. We provide new evidence that the stretch activation is dependent on nitric oxide (NO) production. Stretch activation could be abolished by the addition of NG‐nitro‐L‐arginine methyl ester (L‐NAME), a competitive inhibitor of NO synthesis, but not by NG‐nitro‐D‐arginine methyl ester hydrochloride, a less active enantiomer of L‐NAME. Adding HGF to the L‐NAME culture restored the activation response, indicating that L‐NAME does not directly inhibit satellite cell activation, but acts upstream from the HGF release. In addition, immunoblots of satellite cell lysate revealed the presence of nitric oxide synthase. These experiments suggest that NO is involved in linking mechanical perturbation of satellite cells to chemical signaling responsible for HGF release from its sequestration in vitro.
Effect of an automatic milking system on milking traits
Authors: HAYASHI Takashi , KAWAMURA Teruo
Published: March 2003

Recent studies in Japan of the effect of automatic milking systems (AMS) on the behavior of dairy cows have confirmed the labor‐saving aspect of AMS, but have not solved some of the problems affecting milking traits. The influence of AMS on milking was examined in 39 Holstein cows at Iwate Agricultural Research Center from June 1998 to December 1999, by measuring and recording the yield per milking, milking finish time, milking frequency, and daily yield of milking. Four milking traits were analyzed separately as the objective variable in a linear model, with parity, days in milking, month after installation of the AMS as independent variables. Primiparous cows milked more frequently in the middle and late stage of lactation, yielded less per milking and less per day in the early stage of lactation than multiparous cows with the AMS. Lower frequencies were observed at noon and midnight for cleaning of the bulk tank. By contrast, higher milking frequency in the forenoon was shown. The yield per milking rose and declined, following a normal lactation curve. However, milking frequency rose slowly, and declined gradually in the late stage of lactation. After installing a one‐way gate, the cows milked more frequently, with a lower yield per milking and a greater daily milk yield, than before installation.
Effect of the strain combination of the donor and recipient on the production efficiency of W‐bearing sperm in mixed‐sex germline chimeric chickens
Authors: KAGAMI Hiroshi , YASUDA Jun , TAGAMI Takahiro , NAITO Mitsuru , MATSUBARA Yuko , HARUMI Takashi , NOGUCHI Takamasa , YAMAMOTO Yasuhiro , TAKAHASHI Taikai , MATSUYAMA Junichi , KOMATSU Hiroyuki , ONO Tamao
Published: March 2003

Effect of the strain combination of the donor and recipient on production efficiency of W‐bearing sperm in mixed‐sex chimeric testes was analyzed. The combinations of the donors and recipients were White Leghorn (WL) and Rhode Island Red (RIR), and vice versa. Generated mixed‐sex chimeras that had the male phenotype at sexual maturity were classified into four groups: (1) a female WL donor and a male RIR recipient; (2) a male WL donor and a female RIR recipient; (3) a female RIR donor and a male WL recipient; (4) a male RIR donor and a female WL recipient. The mean number of W‐bearing sperm detected by in situ hybridization among 10 000 sperm observed were 147, 165, 30 and 45 in groups 1, 2, 3 and 4, respectively. The numbers in groups 1 and 2 were both significantly higher than those of groups 3 and 4 (P < 0.05). The combination of a WL donor and a RIR recipient produced W‐bearing sperm more efficiently than the reverse combination.
Changes in the population of lymphocytes expressing CD4 and CD8 during the process of atresia of white follicles in hens
Authors: YOSHIMURA Yukinori , KITAMURA Akihiko
Published: March 2003

The aim of this study was to determine whether the population of lymphocytes expressing CD4 and CD8 molecules changed in the white follicles during atresia in chickens. Frozen sections of healthy, early atretic, advanced atretic and late atretic follicles were immunostained for CD4 and CD8, and the populations of positive cells were analyzed under a light microscope. In the healthy, early atretic and advanced atretic follicles both CD4+ and CD8+ cells were localized in the theca layer, but not in the granulosa layer. However, an influx of CD4+ and CD8+ cells was observed not only in the theca but also in the follicular cavity that was formed by disintegration of the oocyte in late atretic follicles. The frequency of CD4+ T cells in the theca layer did not differ among healthy, early atretic and advanced atretic follicles, but was significantly increased in the late atretic follicles (P < 0.05). The frequency of CD8+ cells showed a pattern of change that resembled that of CD4+ T cells, with a significantly greater population in late atretic follicles than the other follicles (P < 0.05). These results suggest that CD4+ and CD8+ cells are increased in the late atretic follicles, probably to promote the tissue regression.
Intestinal morphology and enteral nutrient absorption of pigeon pea seed meal in piglets
Authors: MEKBUNGWAN Apichai , YAMAUCHI Koh‐en , THONGWITTAYA Narin
Published: March 2003

This study was conducted to establish the relationship between histological alterations of the intestinal villus and intestinal function, and to histologically assess the enteral nutrient absorption of raw pigeon pea seed meal (PM). Piglets were allotted into five groups: feed withdrawal for 3 days or 5 days, refeeding soybean meal (SM) or PM for 2 days after the 3‐day fast, and access ad libitum to conventional feed for the last 2 days without fasting. After the end of each experiment, the intestinal segment and duodenum of each piglet were processed and examined by light and scanning electron microscopy, respectively. After fasting, villus height, cell area and cell mitosis number were decreased in most parts of each intestinal segment, and duodenal villus tips had a smooth surface. After refeeding SM or PM, the decrease in body weight improved, but there was not a significant difference between them. The atrophic morphology of the intestine was reversed by refeeding SM, suggesting that the intestinal villi might be activated by absorption of SM. On the other hand, in the piglets refed PM, the recovery of light microscopic parameters and duodenal villus tip morphology was less clear than with SM. The present histological results suggest that although the absorption of PM is less than that of SM, the PM nutrients might be effectively absorbed, even in the raw form, and establish that in pigs intestinal histological alterations correspond well with intestinal absorptive function.
Evaluation of beef tallow as a natural source of conjugated linoleic acid
Authors: KAWAHARA Satoshi , TAKENOYAMA Shin‐ichi , NAGATO Chizuko , MUGURUMA Michio , ITO Tatsumi , YAMAUCHI Kiyoshi
Published: March 2003

Cis‐9, trans‐11 conjugated linoleic acid (9c, 11t CLA) is a potential anticarcinogen that is found in higher concentrations in beef lipids. However, the effect of CLA on lipid peroxidation, which is closely related to carcinogenesis, is controversial. In this study, we determined the levels of 9c, 11t CLA contents and thiobarbituric acid reactive substances (TBARS) in the tissues of rats fed beef lipid. Sprague‐Dawley rats (male, 8 weeks old) were fed experimental diets containing 20% lyophilized beef, and 12% beef tallow or vegetable oils, for 56 days. With the exception of the brain, the tissues from the rats fed the experimental diets accumulated 9c, 11t CLA, depending on the levels of CLA in the diets. The beef tallow group showed significantly higher 9c, 11t CLA contents in all tissues examined than the other diet groups. The intake of beef lipid did not affect the TBARS levels in the rat tissues. The hepatic lipid content from the beef tallow group was lower than that from the group fed vegetable oils. These results suggest that beef is a good source of 9c, 11t CLA, and that the intake of an appropriate level of beef lipid is not hazardous to health.
The regional effects of CO2 and landscape change using a coupled plant and meteorological model
Authors: Eastman Joseph L. , Coughenour Michael B. , Pielke Roger A.
Published: March 2003

A meteorological model, the Regional Atmospheric Modelling System (RAMS), and a plant model, the General Energy and Mass Transfer Model (GEMTM), are coupled in this study. The integrated modelling system was used to investigate regional weather conditions in the central grasslands of the USA for three experimental scenarios:

• land cover is changed from current to potential vegetation;

• radiative forcing is changed from 1 × CO2 to 2 × CO2; and

• biological CO2 partial pressures are doubled.

Results indicate that the biological effect of enriched CO2, and of land‐use change exhibit dominant effects on regional meteorological and biological fields, which were observed for daily to seasonal time scales and grid to regional spatial scales. Simulated radiation impacts of 2 × CO2 were minimal, with interactive effects between the three experimental scenarios as large as the radiational impact alone. Model results highlight the importance of including 2 × CO2 biological effects when simulating possible future changes in regional weather.
Elevated atmospheric CO2 alters wood production, wood quality and wood strength of Scots pine (Pinus sylvestris L) after three years of enrichment
Authors: Ceulemans R. , Jach M. E. , Van De Velde R. , Lin J. X. , Stevens M.
Published: March 2003

Scots pine (Pinus sylvestris L.) trees were grown in open top chambers for three years under ambient and elevated CO2 concentrations. The trees were aged 3 y at the beginning of the CO2 exposure, and the effects of the treatment on total stem volume, stem wood biomass, wood quality and wood anatomy were examined at the end of the exposure. The elevated CO2 treatment lead to a 49% and 38% increase in stem biomass and stem wood volume, respectively. However, no significant effects of the elevated CO2 treatment on wood density were observed, neither when green wood density was estimated from stem biomass and stem volume, nor when oven‐dry wood density was measured on small wood samples. Under elevated CO2 significantly wider growth rings were observed. The effect of elevated CO2 on growth ring width was primarily the result of an increase in earlywood width. Wood compression strength decreased under elevated CO2 conditions, which could be explained by significantly larger tracheids and the increased earlywood band, that has thinner walls and larger cavities. A significant decrease of the number of resin canals in the third growth ring was observed under the elevated treatment; this might indicate that trees produced and contained less resin, which has implications for disease and pest resistance. So, although wood volume yield in Scots pine increased significantly with elevated CO2 after three years of treatment, wood density remained unchanged, while wood strength decreased. Whilst wood volume and stem biomass production may increase in this major boreal forest tree species, wood quality and resin production might decrease under future elevated CO2 conditions.
People with learning disabilities as witnesses in court: What questions should lawyers ask?
Authors: Kebbell Mark R. , Hatton Chris , Johnson Shane D. , O'Kelly Caitriona M. E.
Published: March 2003

People with learning disabilities (LDs) are likely to be at greater risk of having crimes committed against them, and testimony from witnesses with LDs is likely to be crucial when many of these crimes are prosecuted. The present authors analysed the transcripts of 16 court cases involving witnesses with LDs and 16 matched court cases involving witnesses without LDs. On the basis of this information and previous research, they discuss three issues: (1) the strengths and vulnerabilities of people with LDs as witnesses in court; (2) the kinds of questioning used by lawyers in courtrooms which can cause problems for witnesses with LDs; and (3) guidance for practitioners concerning alerting the judge to their role in preventing constraining and coercive lawyer questioning in court. The authors conclude that many people with LDs can be competent witnesses in court, but that hostile lawyers in particular use constraining and coercive questioning strategies which have a particularly negative impact on the testimony of witnesses with LDs. Judges should be informed of appropriate and inappropriate lawyer questioning strategies in advance of trials to enable them to effectively manage the questioning of lawyers in the courtroom.
Paz2 and 13 other PAZ gene products regulate vacuolar engulfment of peroxisomes during micropexophagy
Authors: Mukaiyama Hiroyuki , Oku Masahide , Baba Misuzu , Samizo Takeshi , Hammond Adam T. , Glick Benjamin S. , Kato Nobuo , Sakai Yasuyoshi
Published: March 2003

Background: In the methylotrophic yeast Pichia pastoris, peroxisomes can be selectively degraded through direct engulfment by the vacuole in a process known as micropexophagy, but the mechanism of micropexophagy is not known.

Results: To gain molecular insights into micropexophagy, we used fluorescence time‐lapse microscopy, coupled with gene‐tagging mutagenesis to isolate P. pastoris mutants defective in micropexophagy. The relevant genes have been designated PAZ genes. Morphological and genetic analyses enabled us to postulate a schematic model for micropexophagy. This new model invokes the generation of new vacuolar compartments as an intermediate structure during micropexophagy. Different classes of paz mutants arrest micropexophagy at distinct stages of the process. Most of APG‐related paz mutants ceased micropexophagy at Stage 1c and that GCN‐family paz mutants ceased micropexophagy at Stage 2. The paz2Δ strain shows a unique phenotype. Paz2 is the homologue of Saccharomyces cerevisiae Apg8, which is necessary for macroautophagy in that yeast. Our analysis revealed that in P. pastoris, Paz2 plays a key role in repressing the engulfment of peroxisomes by the vacuole before the onset of micropexophagy. Paz2 is proteolytically processed by another autophagy‐related Paz protein Paz8, but this processing is not required for the ability of Paz2 to suppress aberrant micropexophagy.

Conclusion: Micropexophagy has been dissected into a multistep reaction that involves 14 identified Paz gene products. Our studies indicate that Paz2 controls the engulfment of peroxisomes by the vacuole, pointing to a novel early function of this protein.
Analysis of blood pressure responses during exercise by logistic function curve in hypertension: effects of age, gender and physical training
Authors: Sugimoto S.‐I. , Takenaka K. , Hirano K. , Miyake Y. , Imaizumi T.
Published: March 2003

During exercise blood pressure fluctuates from minute to minute and does not rise linearly with time. Blood pressure responses were evaluated during exercise by a logistic function curve. Thirty‐nine hypertensive patients underwent exercise testing with an ergometer, employing a multistage method (25 watts increment, every 3 min). We plotted the exercise duration on the X‐coordinate and systolic blood pressure on the Y‐coordinate and blood pressure was assumed to form a logistic curve for exercise duration. The relationship of systolic blood pressure vs. exercise duration was better fitted into a logistic function curve than a linear regression model. The logistic curve was defined by lower plateau, upper plateau, SPX (the X‐coordinate at the shift point) and df (SPX), the maximal slope at the shift point. The effects of aging, gender and physical training were then analyzed on the curve. Aging did not affect lower plateau, upper plateau and SPX but augmented df (SPX), indicating greater blood pressure responses in older subjects during exercise. In females the curve was shifted to the left compared to males (SPX: 4.9 vs. 8.3 min, P < 0.05) without changes in plateaux and df (SPX), indicating greater blood pressure responses than males. Physical training for 3 weeks decreased the lower plateau from 157 to 144 mmHg (P < 0.05) and shifted the curve to the right (SPX: 7.1 vs. 8.6 min, P < 0.05), indicating unchanged blood pressure responses after training because of the opposite effects by decreases in the lower plateau vs. the curve shift to the right. In conclusion, blood pressure during exercise is better delineated by a logistic function curve than a linear regression model. The biological or physiological significance of df (SPX) is not clear at present and needs further investigations.
Effects of red blood cell hyperaggregation on the rat microcirculation blood flow
Authors: Durussel J.J. , Berthault M.F. , Guiffant G. , Dufaux J.
Published: March 2003

This study presents the effects of red blood cell (RBC) hyperaggregation on the blood flow and pressure in the rat mesentery and cremaster network. We exclusively studied in situ non‐vasodilated organs, in order to maintain the physiological regulation mechanisms. Dextran 500 was injected at different concentrations to increase RBC aggregation. The aggregation rate was measured on very small blood samples with an erythroaggregameter (SEFAM) which evaluated the disaggregating shear stress (τD) needed to break the RBC aggregates. Microscopic observations and laser Doppler velocimetry were used to quantify the flow rate. The plasmatic dextran concentration (C) increase had different correlated effects: for example, τDincreased from 3 dynes cm−2 (for the control sample) to 14 dynes cm−2 (for C = 75 μM L−1); the flow rate was reduced threefold and very large aggregates were observed in the venules; the arteriolar pressure increased while venular pressure decreased. In order to differentiate the effects of RBC hyperaggregation from those of plasma hyperviscosity (due to dextran 500) on microcirculatory blood flow, we injected an RBC antiaggregating drug (troxerutine) (50 or 100 mg kg−1 IV). The consequences were a high reduction for (τD) (from 14 dynes cm−2–9 dynes cm−2), smaller aggregates and higher blood flow in the venules. No effect of troxerutine was observed on plasma viscosity (plasma control: 1,9 cP with or without troxerutine; plasma with dextran at C = 75 μM L−1: 2,45 cP with or without troxerutine). The results strongly suggest that RBC aggregation has a significant influence on blood flow rate in the microcirculatory network.
Rapid recovery of power output in females
Authors: CHERRY  , LAKOMY  , BOOBIS  , NEVILL
Published: March 2003

The purpose of the present study was to examine whether the magnitude of the changes in the concentration of muscle metabolites influences the recovery of power output following short‐term maximal intensity cycle exercise performed at different average pedalling rates. In part A of the study eight female subjects performed four trials on a cycle ergometer. Two trials involved maximal sprints of 30‐ and 6‐s duration separated by a very short (2–3 s) recovery period. Average pedal rate during the first 30‐s sprint was manipulated by employing resistances of either 7.5 or 10.1% of body weight; the second sprint always being performed against 7.5% BW. In two further trials subjects performed only a single 30‐s sprint against the two resistances with pre‐ and post‐exercise muscle biopsies and blood samples being taken. Peak power in the second sprint was significantly higher (442 ± 31W vs. 402 ± 33W; P < 0.05) following prior exercise against the greater resistance during which average pedal rate was lower (≈ 26%; P < 0.01) compared with the lesser resistance. However, despite this the muscle metabolite responses to the first sprint were similar (ΔPCr (7.5 vs. 10.1% applied resistance) –55 vs. –59 mmol kg dry muscle−1: ΔLactate + 104 vs. +107 mmol kg dry muscle−1: both P > 0.05). In part B of the study six female subjects performed 19 trials in which the recovery interval between a maximal 30‐s sprint (where average pedalling rate was manipulated in a manner similar to part A) and a 6‐s sprint ranged from 0 to 300 s. The rate of restoration of power output was influenced by the average pedal rate in sprint 1 only for recovery durations of up to 3 s. These findings suggest that the recovery of power is not exclusively determined by muscle metabolites, in particular PCr, when the recovery duration is very short (≤ 3 s). As it has been previously shown that the pattern of muscle activation influences ionic balance it is speculated that ionic factors may be very important in the early and rapid recovery of power.
Forskolin–induced down–regulation of Na+,K+–ATPase activity is not associated with internalization of the enzyme
Authors: ANDERSSON  , CHENG  , APERIA
Published: March 2003

Activation by protein kinase A by forskolin phosphorylates and inactivates Na+,K+‐ATPase in COS‐7 cells (Cheng et al. 1997b). In this study we show, using [3H]ouabain binding, that forskolin‐induced inhibition of Na+,K+‐ATPase activity is not because of internalization of the enzyme. The effect of forskolin on Na+,K+‐ATPase activity was examined by two independent methods, ouabain‐sensitive 86Rb+ uptake in intact cells and ATP hydrolysis in microsomal preparations from cells. The change in number of functional pumps on cell surface before and after protein kinase A activation was assessed by [3H]ouabain binding measured under equilibrium conditions. Cells, which had been ATP‐depleted by antimycin A and 2‐deoxyglucose treatment, served as a positive control for the internalization of Na+,K+‐ATPase. Activation of protein kinase A with forskolin in combination with the phosphodiesterase inhibitor 3‐isobutyl‐1‐methyl xanthine, inhibited Na+,K+‐ATPase activity, but this treatment had no effect on specific ouabain binding. No change in ouabain binding was found following activation of protein kinase C by phorbol ester or diacyl glycerol analogue treatment in cells. These data suggest that protein kinase A phosphorylation and inhibition of Na+,K+‐ATPase activity does not lead to any internalization of the enzyme in COS‐7 cells.
Proximal tubular function in adult rats treated neonatally with enalapril
Authors: GURON  , NILSSON  , LEYSSAC  , SUNDELIN  , FRIBERG
Published: March 2003

Neonatal treatment with angiotensin‐converting enzyme (ACE) inhibitors or the angiotensin II type‐1 receptor antagonist losartan in rats induces irreversible renal histological abnormalities, mainly papillary atrophy, in association with an impairment in urinary concentrating ability. The aim of the present study was to assess proximal tubular function in adult rats treated neonatally with enalapril. Male Wistar rats received daily, intraperitoneal injections of either enalapril (10 mg kg−1) or isotonic saline vehicle from 3 to 24 days of age. In 15‐week‐old, hydropenic rats we analysed: (i) proximal tubular iso‐osmotic fluid reabsorption using the method of lithium clearance; and (ii) maximal tubular
D‐glucose reabsorption (TmG), under pentobarbital anaesthesia. The main findings were that neonatally enalapril‐treated rats showed: (i) reductions in absolute (APRH2O) and fractional (FPRH2O) iso‐osmotic fluid reabsorption in the proximal tubules (APRH2O: 0.50 ± 0.02 vs. 0.64 ± 0.03 mL min−1 g KW−1, P < 0.05; FPRH2O: 58 ± 3 vs. 68 ± 2%, P < 0.05); and (ii) a normal TmG. In addition, during baseline clearance measurements neonatally enalapril‐treated rats showed increases in urine volume and fractional excretion rates of sodium and potassium, a reduction in urine osmolality, whereas glomerular filtration rate and effective renal plasma flow were unaltered. These results suggest that neonatal ACE inhibition produces an irreversible, but differentiated, abnormality in proximal tubular function. Thus, the development of a normal proximal tubular function in the rat seems to be dependent on an intact renin‐angiotensin system, (RAS) neonatally.
Lactate transport in L6 skeletal muscle cells and vesicles: allosteric or multisite mechanism and functional membrane marker of differentiation
Authors: BEAUDRY  , MOUAFFAK  , ABIDA K. EL , RIEU  , MENGUAL
Published: March 2003

Membrane lactate transport was studied in skeletal muscle cells and membrane vesicles from the L6 line in relation to in vitro myogenesis. In myoblasts, lactate was transported by simple diffusion and insensitive to classical inhibitors: a positive correlation between onset of creatine kinase activity and lactate transport in differentiated myotubes was observed and could be considered to be a functional marker of cell differentiation. In myotubes, complete analysis of the velocity curves (direct coordinates, Eadie–Scatchard plots, Hill plots) gave parameters showing that lactate was carried by an allosteric or multisite system. This was confirmed by using sarcolemmal vesicles and specific inhibitors. In whole cells, α‐cyano‐4‐hydroxycinnamic acid (CIN) and parachloromercuribenzylsulphonic acid (pCMBS) inhibited the maximal velocity without modifying the global cooperativity of the system. The weak effect of 4,4′‐diisothiocyanostilbene‐2,2'‐disulphonic acid (DIDS), which has a low affinity constant (Ki = 22.5 μM), implicated the monocarboxylate system rather than the anionic exchanger as a carrier system in muscle cells. CIN and DIDS exhibited one type of interaction with lactate carriers, and the curvilinear shape of the lactate Hill plot with or without inhibitors suggested that inhibitors were active at the same family of interaction sites and had a common range of affinities. The apparent competitive inhibition of pyruvate (Ki = 3.2 m
M) did not modify the transport pathway of lactate in L6 myotubes. In conclusion, kinetic analysis of lactate transport in the presence or absence of inhibitors gave evidence for a multisite lactate carrier activity in myotubes composed of two systems at least, related to two or three isoforms of lactate carriers.
Interaction between 3α‐hydroxy‐5α‐pregnan‐20‐one and carbachol in the control of neuronal excitability in hippocampal slices of female rats in defined phases of the oestrus
Authors: LANDGREN  , WANG  , BÄCKSTRÖM  , JOHANSSON
Published: March 2003

The effects of 3α‐hydroxy‐5α‐pregnan‐20‐one (allopregnanolone) and carbachol on CA1 and dentate gyrus action potentials were studied in hippocampus slices in premature, follicular and luteal phase rats. A 0.5 nL droplet of allopregnanolone (12.5 μmol L−1), carbachol (5 μmol L−1) or a mixed solution of 12.5 μmol L−1 allopregnanolone and 5 μmol L−1 carbachol was applied locally onto the stratum oriens‐pyramidale or granular layer. The amplitude of CA1 population spike (POPSP) was reduced by allopregnanolone (−38 ± 3%) and carbachol (−21 ± 4%) in the luteal phase slices. The mixture of allopregnanolone and carbachol doubled this inhibition (−77 ± 6%). The inhibition caused by allopregnanolone and the mixture of allopregnanolone and carbachol in CA1 was significantly larger in the luteal phase than in the follicular phase (P = 0.02 and 0.0002). In the granular layer of the dentate gyrus, these inhibitions showed no significant difference between the phases. Neither in CA1 nor in the dentate gyrus did the carbachol inhibition differ between the phases. Perfusion with 5–10 μmol L−1 carbachol caused an increasing inhibition of the POPSP during the first few minutes. Thereafter the inhibition gradually diminished and was replaced by a facilitation. The local allopregnanolone inhibition was enhanced by simultaneous carbachol perfusion. Picrotoxin (100 μmol L−1) substantially reduced the allopregnanolone but not the carbachol inhibition. Atropine (10 μmol L−1) blocked the carbachol response, but not the allopregnanolone inhibition. Perfusion with a mixed solution of picrotoxin and atropine reduced, but did not block, the inhibition caused by local application of allopregnanolone or by the mixture of allopregnanolone and carbachol. Our data suggest that neuroprogestine modulators of the GABAA‐receptor‐mediated inhibition may play a significant role in the control of the cholinergic excitation in the hippocampus.
Partial inhibition of Na,K‐ATPase activity in cultured rabbit non‐pigmented ciliary epithelium following an episode of cytoplasmic ATP depletion
Authors: KUWAHARA  , CHIN  , DELAMERE
Published: March 2003

Ouabain‐sensitive ATP hydrolysis (Na,K‐ATPase activity) was measured in digitonin‐permeabilized monolayers of cultured cells derived from rabbit non‐pigmented ciliary epithelium. Diminished Na,K‐ATPase activity was observed in cells that had been pre‐treated 10 min with the protein kinase C activator, PDBu, as well as in cells that had been cooled to 4 °C for 4 h then rewarmed to 37 °C for 30 min (cool–rewarm manoeuvre). In the intact cells, ouabain binding was not decreased either by PDBu treatment or the cool–rewarm manoeuvre. However, both PDBu and the cool–rewarm manoeuvre increased the rate of ouabain‐sensitive potassium (86Rb) uptake measured in intact cells. Cell ATP content was diminished in PDBu‐treated cells and cells subjected to the cool–rewarm manoeuvre. We suggest that an episode of ATP depletion might initiate a mechanism which causes lasting, partial inhibition of Na,K‐ATPase activity. In keeping with this suggestion, diminished Na,K‐ATPase activity was observed in cells that had been pre‐treated 20 min with the metabolic inhibitors CCCP or rotenone and in cells pre‐treated 2.5 h in dextrose‐free medium. This study illustrates that Na,K‐ATPase activity measured in the permeabilized cell is a complex parameter which is not necessarily a reliable indicator of sodium pump responses in the intact cell.
Dissociation between force and [Ca2+]i during extra systoles in guinea‐pig ventricular muscle microinjected with fura‐2
Authors: ARHEDEN  , HELLSTRAND  , WOHLFART
Published: March 2003

Thin trabeculae were dissected from the right ventricle of guinea‐pig heart and stimulated to contract isometrically at 0.5 Hz (26 °C). Rapid and transient changes of force were obtained by inducing three extra systoles (ES1–3) at 450‐ms intervals. The two regular contractions (P1–2) following (ES1–3) were potentiated. Fura‐2 salt was microinjected into the preparation to monitor intracellular calcium ([Ca2+]i). Three distinct phases of [Ca2+]i were seen: (1) a rapid rising phase to about 200 nmol L−1, (2) a slower rising phase to a peak at 400 nmol L−1, and (3) a slow decline to about 50 nmol L−1. During ES1, there was a discrepancy between force, which decreased, and peak [Ca2+]i, which increased to 600 nmol L−1. It is likely that the increased [Ca2+]i during the extra systoles reflects increased sarcolemmal calcium inflow, causing post‐extra‐systolic potentiation. Ryanodine (1–2 μM) was added to inhibit the intracellular calcium release and thus reduce the intracellular [Ca2+]i gradients following excitation. Ryanodine inhibited phase 1 of [Ca2+]i and abolished post‐extra‐systolic potentiation. There was a close relationship between dF/dt and [Ca2+]i with ryanodine during control and ES1–3. It is likely that fura‐2 reports a spatially averaged [Ca2+]i and that phase 1 of the signal therefore apparently underestimates activator calcium in the close vicinity of the contractile elements.
Physiological oxygen concentration gives an oscillating spontaneous tone in guinea‐pig tracheal preparations
Authors: SKOGVALL  , GRAMPP
Published: March 2003

The spontaneous tone in isolated six‐segment preparations of guinea‐pig trachea was examined. In 12% oxygen (corresponding to normal systemic arterial oxygen pressure) the preparations developed a spontaneous tone with regular oscillations (6.6 min−1), usually grouped in so‐called complexes (7.5 h−1). The average tone during an entire complex amounted to 12% of a maximum KCl‐induced contraction. The complex tone was highly stable during observation periods of at least 4 h, and was reversibly transformed to the ‘classical’, smooth type when exposed to 94% oxygen. Stretch of preparations in low oxygen resulted in a fast, stable change of tone, while preparations in traditionally high oxygen reacted slower, and lost 40% of the active tension during the hour following stretch. Indomethacin (10 μM) did not eliminate the oscillating behaviour, but reduced the average size of the tone by 44%. Exposure to the C‐fibre blocking agent capsaicin (50 μM) and the local anaesthetic lidocaine (1 m
M) completely eliminated the oscillations and complexes, although the preparations retained a smooth tone. Atropine, propranolol and tetrodotoxin did not affect the complex tone. This study demonstrates for the first time that guinea‐pig tracheal preparations that are exposed to near‐physiological oxygen concentrations develop a new type of oscillating spontaneous tone, which is largely prostaglandin‐independent, but appears to require transmitter release from sensory C‐fibres. We argue that the complex tone is physiological, and that traditionally high oxygen (95%) probably results in non‐physiological hyperoxic changes in this preparation.
Effects of pituitary adenylate cyclase activating polypeptide‐27 (PACAP) and vasoactive intestinal polypeptide (VIP) on chloride in HT29 cells studied by X‐ray microanalysis
Authors: ZHANG  , ROOMANS
Published: March 2003

The colon cancer cell line HT29 is a useful model to study intestinal chloride secretion. These cells have both cAMP‐activated and calcium‐activated chloride channels. Changes in elemental content of the cells after stimulation with agonists were determined by X‐ray microanalysis in the scanning or scanning transmission electron microscope. Exposure of HT29 cells to pituitary adenylate cyclase activating polypeptide‐27 (PACAP) caused a transient decrease in the cellular Cl and K concentrations, indicating (net) efflux of chloride. The effect of PACAP is inhibited by somatostatin, which is known to inhibit cAMP‐activated as well as calcium‐activated chloride secretion and by U‐73122, an inhibitor of phospholipase C. Alloxan, an inhibitor of adenylate cyclase, did not significantly affect the PACAP‐induced loss of chloride. The calcium‐chelating agent EGTA inhibited the PACAP‐induced loss of chloride, indicating the need for extracellular calcium ions. Also vasointestinal polypeptide (VIP) caused a decrease of the cellular chloride concentration in HT29 cells. VIP‐induced loss of chloride could be inhibited by pre‐treating the cells with somatostatin or UK14,304, an alpha‐2 adrenergic agonist that has been shown previously to inhibit purinergically activated chloride efflux. Our results indicate that there is cross‐talk between the cAMP‐ and the calcium‐activated pathways for chloride secretion in HT29 cells.
Changes in myosin heavy chain profile of mature regenerated muscle with endurance training in rat
Authors: BIGARD  , JANMOT  , SANCHEZ  , SERRURIER  , POLLET  , D’ALBIS
Published: March 2003

The objective of the present study was to examine the response of fast‐twitch muscle to endurance training long after the muscle had regenerated from toxin injury. Seventeen male Wistar rats were randomly assigned to a sedentary (S, n = 10) or a trained group (T, n = 7). Endurance training by treadmill running (5 days week−1, 30 m min−1, 7% grade, 2 h day−1 for 5 weeks) was initiated 5 weeks after myofibre degeneration was induced in the right extensor digitorum longus muscle (EDL) by two injections of 0.2 mL of the unfractionated venom from Naja nigricollis snake. Gel electrophoresis analyses showed that training alone resulted in a 140% increase in type IIX myosin heavy chain (MHC) (P < 0.01) and a slight decrease in type IIB MHC (−14% P < 0.05). Regeneration alone induced an increase in both type IIA and IIX MHC expression (103%, P < 0.05, and 131%, P < 0.01, respectively), and a concomitant decrease in the percentage of type IIB MHC (P < 0.05). The shift from type IIB toward type IIA MHC composition observed in regenerated muscles of T rats resulted not only from an additive, but from a cumulative effect of training and regeneration. Immunohistochemical analysis of MHC content in individual fibres showed similar changes. These data suggest that the impact of endurance training on fast‐type MHCs was more marked in mature regenerated muscles than in regenerating ones, and provide evidence of the heightened plasticity of fully regenerated muscles to repeated exercise.
Relationship between systemic blood pressure, airway blood flow and plasma exudation in guinea‐pig
Authors: CUI  , ARAKAWA  , KAWIKOVA  , SKOOGH  , LÖTVALL
Published: March 2003

Plasma exudation in the airways is mainly dependent on microvascular permeability of the tracheobronchial circulation and may be affected by local blood flow. Aortic blood pressure provides the major inflow pressure to tracheobronchial circulation. Therefore, systemically administered vasoconstrictors, in doses enough to increase systemic blood pressure, may theoretically increase the blood flow in the tracheobronchial circulation by enhancing inflow pressure. Consequently, this may influence plasma exudation induced by inflammatory mediators in the airways. To test this hypothesis, we used guinea‐pigs to study: (1) the effects of i.v. vasoconstrictors (methoxamine and angiotensin II) on blood flow in the tracheal mucosa and in the leg skeletal muscle (Laser‐Doppler flowmetry); (2) the effects of i.v. vasoconstrictors on plasma exudation induced by tracheal administration of the inflammatory mediator bradykinin (150 nmol). We found that i.v. methoxamine and angiotensin II significantly increase tracheal mucosa blood flow and systemic blood pressure. The increase in tracheal mucosa blood flow was, in the case of angiotensin II, found to be significantly related to the increase in systemic blood pressure. In separate experiments, pre‐treatment with i.v. methoxamine and angiotensin II significantly potentiates Evan’s Blue dye exudation induced by bradykinin in the trachea and main bronchi. We conclude that i.v. methoxamine and angiotensin II potentiate bradykinin‐induced plasma exudation in the guinea‐pig airways, possibly by increasing the local blood flow. The increase in the local blood flow is most likely induced by enhanced systemic blood pressure (inflow pressure), owing to a redistribution of the total body blood flow.
Localization of carbonic anhydrase in swimbladder of European eel (Anguilla anguilla) and perch (Perca fluviatilis)
Authors: WÜRTZ  , SALVENMOSER  , PELSTER
Published: March 2003

The distribution of carbonic anhydrase in swimbladder tissue and especially in gas gland cells of the European eel (Anguilla anguilla) and the perch (Perca fluviatilis) was analysed using histochemical staining according to
Hansson (1967), with modifications proposed by
Ridderstråle (1991). While in the European eel, gas gland cells are distributed as a single layered epithelium over the whole secretory part of the swimbladder, the gas gland of the perch consists of a compact, richly vascularized ‘multilayered’ epithelium, in which gas gland cells have contact with the swimbladder lumen via small channels. In spite of these differences in organization, membranes of gas gland cells near blood vessels are richly folded in both species. A strong histochemical staining for carbonic anhydrase was observed in these membrane foldings. With prolonged incubation times a positive reaction was also observed in the cytoplasm of gas gland cells. In addition, the vascular endothelium and the erythrocytes showed a positive histochemical reaction. No staining, however, was visible in apical membranes towards the lumen of the swimbladder. In the perch, swimbladder epithelial cells outside the gas gland showed no positive staining of carbonic anhydrase. The results thus indicate that carbonic anhydrase activity is especially concentrated in membranes facing blood vessels. This suggests that a rapid equilibrium of the CO2/HCO3− reaction in the intracellular as well as in the extracellular space is essential for swimbladder function.
The protein tyrosine kinase pathway is not involved in the regulation of K+ transport across the rat colon
Authors: Heinke  , Hörger  , Diener
Published: March 2003

The protein tyrosine kinase inhibitor, genistein, is known to activate the cystic fibrosis transmembrane regulator (CFTR) Cl− channel and to inhibit K+ currents across the rat colonic epithelium. The aim of the present study is to answer the question whether these effects are involved in the regulation of transepithelial K+ transport. Therefore, the action of genistein on K+ transport in rat proximal and distal colon was studied by measuring unidirectional fluxes, uptake and efflux of Rb+ in mucosa‐submucosa preparations. All effects of genistein (5 × 10−5 mol L−1) were tested in the presence of a low concentration of forskolin (2 × 10−7 mol L−1), because prestimulation of the cAMP pathway has been shown to be a prerequisite for a secretory action of genistein. Forskolin caused an increase in the serosa‐to‐mucosa flux of Rb+ (J Rbsm) thereby stimulating net K+ secretion in the proximal and distal colon. None of these effects was further enhanced after administration of genistein. Neither mucosal uptake of Rb+, representing mainly the activity of the H+‐K+‐ATPase in the distal colon, nor serosal Rb+ uptake, representing, e.g. the activity of the Na+‐K+‐2Cl− cotransporter, were affected by genistein. Also the efflux of Rb+ across the apical or the basolateral membrane, an indicator for the apical and basolateral K+ conductance, was unchanged in the presence of genistein. These results demonstrate that the K+ channels inhibited by genistein are not involved in transepithelial K+ transport.