Wrapper, a novel member of the Ig superfamily, is expressed by midline glia and is required for them to ensheath commissural axons in Drosophila

The midline glia are specialized, nonneuronal cells at the midline of the Drosophila central nervous system (CNS). During development, the midline glia provide guidance cues for extending axons. At the same time, they migrate and help separate the two axon commissures. They then wrap around and ensheath the commissural axons. In many segments, a few of the glia do not enwrap the axons, and these cells die. The wrapper gene encodes a novel member of the immunoglobulin (Ig) superfamily. Wrapper protein is expressed specifically on the surface of midline glia. In wrapper mutant embryos, the midline glia express their normal guidance cues and migrate normally. However, they do not ensheath the commissural axons, and as a result, the glia die. In the absence of Wrapper, the two axon commissures are not properly separated.

Ki67 labelling index correlates with stage and histology but not significantly with prognosis in thymoma

AIMS

There have been several cell kinetic studies of thymoma, but the effectiveness of using Ki67 antibody as a tool to measure proliferative activity in this tumour was rarely evaluated. We carried out an immuno-histochemical study using this antibody to assess the clinicopathological correlation and the prognostic significance of this technique.

METHODS AND RESULTS

Ninety-one cases of thymoma were collected. Double immunostaining with Ki67 and cytokeratin KL-1 antibodies was performed on paraffin sections. Ki67 labelling index (LI) was expressed as a percentage of Ki67 immunopositive nuclei by counting at least 1000 epithelial cells. The LIs were correlated with stages, histological subtypes based on both Lattes-Bernatz and Müller-Hermelink-Kirchner classifications, and length of survival. There were statistically significant differences of LIs between stage I and stage III and between stage I and stage IV tumours. Histologically, statistically significant differences were identified between predominantly epithelial thymoma and every other subtype of the Lattes-Bernatz classification and between well-differentiated thymic carcinoma and medullary or mixed thymomas of the Müller-Hermelink-Kirchner classification. Regarding the prognostic implication of Ki67 LI, although there appeared a trend that patients with tumours of higher LIs had slightly worse survival, the difference was not statistically significant in both univariate and multivariate survival analyses.

CONCLUSIONS

We have demonstrated the proliferative potential in thymoma is associated with stage and histology. However, its clinical usefulness is limited on account of the overlap of LIs and lack of prognostic significance.

alpha2-adrenoceptors modulate NMDA-evoked responses of neurons in superficial and deeper dorsal horn of the medulla

Extracellular single unit recordings were made from neurons in the superficial and deeper dorsal horn of the medulla (trigeminal nucleus caudalis) in 21 male rats anesthetized with urethan. NMDA produced an antagonist-reversible excitation of 46 nociceptive as well as nonnociceptive neurons. Microiontophoretic application of a preferential alpha2-adrenoceptor (alpha2AR) agonist, (2-[2, 6-dichloroaniline]-2-imidazoline) hydrochloride (clonidine), reduced the NMDA-evoked responses of 86% (6/7) of nociceptive-specific (NS) neurons, 82% (9/11) of wide dynamic range (WDR) neurons, and 67% (4/6) of low-threshold (LT) neurons in the superficial dorsal horn. In the deeper dorsal horn, clonidine inhibited the NMDA-evoked responses of 94% (16/17) of NS and WDR neurons and 60% (3/5) of LT neurons. Clonidine facilitated the NMDA-evoked responses in 14% (1/17) of NS, 9% (1/11) of WDR, and 33% (2/6) of LT neurons in the superficial dorsal horn. Idazoxan, an alpha2AR antagonist, reversed the inhibitory effect of clonidine in 90% (9/10) of neurons, whereas prazosin, an alpha1-adrenoceptor antagonist with affinity for alpha2BAR, and alpha2CAR, were ineffective. We suggest that activation of alpha2ARs produces a predominantly inhibitory modulation of the NMDA-evoked responses of nociceptive neurons in the medullary dorsal horn.

A high throughput screen to identify secreted and transmembrane proteins involved in Drosophila embryogenesis

Secreted and transmembrane proteins play an essential role in intercellular communication during the development of multicellular organisms. Because only a small number of these genes have been characterized, we developed a screen for genes encoding extracellular proteins that are differentially expressed during Drosophila embryogenesis. Our approach utilizes a new method for screening large numbers of cDNAs by whole-embryo in situ hybridization. The cDNA library for the screen was prepared from rough endoplasmic reticulum-bound mRNA and is therefore enriched in clones encoding membrane and secreted proteins. To increase the prevalence of rare cDNAs in the library, the library was normalized using a method based on cDNA hybridization to genomic DNA-coated beads. In total, 2,518 individual cDNAs from the normalized library were screened by in situ hybridization, and 917 of these cDNAs represent genes differentially expressed during embryonic development. Sequence analysis of 1,001 cDNAs indicated that 811 represent genes not previously described in Drosophila. Expression pattern photographs and partial DNA sequences have been assembled in a database publicly available at the Berkeley Drosophila Genome Project website (). The identification of a large number of genes encoding proteins involved in cell-cell contact and signaling will advance our knowledge of the mechanisms by which multicellular organisms and their specialized organs develop.

[Studies on late replication bands of giant panda (Ailuropoda melanoleuca) chromosomes]

Using the cultured giant panda (Ailuropoda melanoleuca) lymphocytes as experimental material, we carried out the terminal marking on the chromosomes which were in replication by adding BrdU (a final concentration: 10 micrograms/ml) about four hours before harvesting the cells. The chromosomes marked by BrdU were proceeded by staining with acridine orange solution (0.05%), irradiated by ultraviolet and counter-stained by Giemsa, we obtained clear chromosomes replication patterns. According to the different replication bands, every chromosome's characteristics in late replication behavior could be identified. In the two X chromosomes of female individual, one X chromosome is obviously much later than the other one. Especially in the large area near centromere on the long arm of late replicating X chromosome. In the male individual, there is also a large area on the long arm of chromosome Y which replicates very late, but the end of long arm of chromosome Y replicates much earlier.

Effects of cyclophosphamide on maturation and subsequent fertilizing capacity of pig oocytes in vitro

This study examines the effects of cyclophosphamide, a widely used anti-cancer agent, on the maturation of pig oocytes and on their subsequent fertilizing capacity in vitro. Pig cumulus-oocyte complexes collected from prepubertal gilts were cultured in Waymouth MB 752/1 medium supplemented with sodium pyruvate (50 micrograms/ml), luteinizing hormone (0.5 microgram/ml), follicle-stimulating hormone (0.5 microgram/ml), and 17 beta-estradiol (1 microgram/ml) in the presence or absence of cyclophosphamide for 24 hr; they then were cultured without hormonal supplements in the presence or absence of cyclophosphamide for an additional 16-24 hr. The breakdown of germinal vesicle (GVBD) and changes in glutathione (GSH) content before in vitro fertilization were assessed. Oocytes containing one polar body and a metaphase plate were regarded as matured. Cytoplasmic maturation as determined by male pronuclear formation following fertilization in vitro was also examined. Treatment of oocytes with increasing concentrations (1-1000 micrograms/ml) of cyclophosphamide for 48 hr resulted in a dose-response inhibition of the rate of maturation, but had no effect on GVBD. Increasing duration (12-48 hr) of treatment with cyclophosphamide (100 micrograms/ml) led to a time-dependent inhibition of nuclear maturation, achieving statistical significance by 24 hr. The addition of cyclophosphamide (100 micrograms/ml) to maturation medium immediately after culture, 12 hr or 24 hr after culture also decreased the percentage of oocytes matured during a 48-h culture period. Exposure of oocytes to cyclophosphamide (100 micrograms/ml) for 40 hr did not prevent sperm penetration, not affect the incidence of polyspermy, or decrease the ability of oocytes to form a male pronucleus at 8 hr after insemination. The concentration of GSH, an important factor for male pronuclear formation, in pig oocytes was determined by an enzymatic cycling assay. The concentration found was 8.15 +/- 1.19 mM per oocyte. Exposure of oocytes to cyclophosphamide (100 micrograms/ml) had no effect on GSH concentration. These results demonstrate that cyclophosphamide directly inhibits the meiotic but not cytoplasmic maturation of pig oocytes in vitro. This inhibitory effect, apparently, is not mediated through a decrease in the level of intracellular glutathione.

Expression of E-cadherin and alpha- and beta-catenins in thymoma

Expression of the cell adhesion molecules including E-cadherin and its cytosolic binding proteins, alpha- and beta-catenins, has been widely studied in a variety of tumours, but not, to date, in thymic epithelial tumours. To observe the expression pattern of these adhesion molecules, immunohistochemical stains for E-cadherin (E-CD) and alpha- and beta-catenins were performed on 89 cases of thymoma which were classified as cortical (57 cases), mixed (18 cases), and medullary (14 cases), based on the classification of Marino and Müller-Hermelink. The majority of cortical thymomas showed diffuse and homogenous membrane immunoreactivity for these molecules (88 per cent for E-CD; 86 per cent for alpha-catenin; 91 per cent for beta-catenin) and the remaining cases showed heterogeneous immunoreactivity, whereas almost all mixed and medullary thymomas revealed decreased expression or were negative. In each histological subtype of thymoma, the expression did not correlate with invasion or with the presence of myasthenia gravis. These results indicate that the expression of E-CD and alpha- and beta-catenins is more closely associated with the histological subtypes of thymoma than with their biological behaviour.

Entropy-driven binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles

This study employed large unilamillar vesicles composed of purchased stratum corneum lipids to investigate the binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles. The partition coefficients of amino acids/dipeptides between the stratum corneum lipid vesicles and the acetate buffer were determined by HPLC. In addition, the binding/partition enthalpy of amino acids/dipeptides with the stratum corneum lipid vesicles was derived by directly measuring the binding/partition heat with isothermal titration calorimetry. According to the binding/petition Gibbs free energy and the binding/partition enthalpy, all the binding/partition of amino acids/dipeptides with the stratum corneum lipid vesicles is endothermic, implying an entropy-driven binding/partition. Also, the equilibrium binding/partition results demonstrate that the partition coefficients of amino acids/dipeptides do not correlate with the transdermal permeability. This finding suggests that either the interaction between the penetrants and the lipid bilayer between corneocytes may not be a determining step or that the paracellular path is not a dominant route of transdermal penetration.

Human growth hormone antagonist (G120R) delivered by a murine yolk sac cell-derived mini-organ decreases the growth rate of mice

Long-term cultured murine embryonic yolk sac cells that are capable of forming capillary structures when cultured on base membrane proteins (Matrigel) were successfully transfected with a human growth hormone antagonist (G120R) gene. Cells that stably express relatively high levels of G120R were co-implanted s.c. with Matrigel into BALB/c mice. G120R can be detected in the sera of those implanted mice for more than 14 days at levels from 4 ng/ml to 28 ng/ml. The insulin-like growth factor-1 levels in the sera of those implanted mice were significantly affected by the delivered G120R. One of the physiological effects of G120R delivered by this murine embryonic yolk sac cell-derived mini-organ system is to decrease the growth rate of the implanted mice. This gene delivery system can also be used as an alternative to transgenic animals to study protein function in vivo.

Increased formation of interstitial hydroxyl radical following myocardial ischemia: possible relationship to endogenous opioid peptides

The effects of myocardial ischemia and reperfusion on interstitial hydroxyl radical production, in the left ventricular myocardium of anesthetized cats, were investigated. Ringer's solution containing salicylic acid was perfused through an implanted microdialysis probe. Hydroxyl radical production was evaluated as the 2,3 and 2,5 dihydroxybenzoic acid (DHBA) concentrations in the microdialysates by an on-line high performance liquid chromatography system. Myocardial ischemia for 60 min, induced by ligation of the left anterior descending coronary artery, significantly increased both 2,3 and 2,5 DHBA levels when compared with the sham-operated cats. Naloxone (1 mg/kg, bolus, intravenous), an endogenous opioid peptide receptor antagonist, significantly suppressed the ischemia-induced production of hydroxyl radicals. Myocardial ischemia also induced cardiac arrhythmia. Naloxone reduced the severity of ischemia-induced arrhythmia, as observed by a significantly lower arrhythmia score (1.4 +/- 0.2 vs. 4.6 +/- 0.4 for control), and by diminished incidence of ventricular tachycardia (0/7 vs. 8/8 for control) and ventricular fibrillation (0/7 vs. 3/8 for control). Furthermore, perfusion of dynorphin (0.25 microgram, 2.5 micrograms and 25 micrograms), an endogenous opioid peptide receptor agonist, increased hydroxyl radical production. Our results suggest that, in anesthetized cats, myocardial ischemia can induce production of interstitial hydroxyl radical in left ventricular myocardium, and this production may involve the actions of released endogenous opioid peptides on their receptors.

Trace elements burden in geriatric hemodialysis patients: a prospective multicenter collaborative study

INTRODUCTION

Hemodialysis therapy and the aging process have been reported to interfere with the trace element (TE) status in the body. This multicenter collaborative study on blood levels of TE in geriatric hemodialysis (HD) patients was carried out with an aim to clarify the impact of the aging process and HD therapy on the TE status in such patients.

METHODS

One hundred and fifty-one HD patients (65 male, 86 female), all aged over 60 (68.2+/-3.86 y), and 112 elderly controls (58 male, 54 female) with a mean age of 67.5+/-3.03 were enrolled. All patients underwent standard HD for at least 6 months. The artificial kidneys used were hollow-fiber dialyzers of cellulose membranes. Water used for HD was prepared by reverse osmosis. Blood was collected in the morning prior to dialysis and after fasting. Atomic absorption spectrophotometry was applied to measure blood levels of Pb, Cd and Hg as well as plasma levels of Cu, Zn and Al. Data are presented as mean +/- SEM. Student's t-test and linear regression were applied for statistics.

RESULTS

Our geriatric chronic HD patients showed a marked elevation of blood Al and decreased plasma Zn concentrations. The blood levels of Cu, Cd, Pb and Hg were within normal limits. The blood concentrations of Al, Cu and Pb were significantly higher in HD patients than in the normal elderly controls, whereas Cd and Hg were similar in both groups, and Zn were lower in HD patients. Plasma Zn value decreased as dialysis duration increased, however there was a reversely linear correlation between plasma Zn and age.

CONCLUSIONS

This data reported can be regarded as a starting point and may serve as an insight to further studies on TE imbalances in geriatric and chronic HD populations.

Tubo-ovarian abscess caused by multidrug resistant Bacteroides gracilis

Bacteroides gracilis infections are very rare and have always been reported to have a polymicrobial etiology. The majority of these infections occur in the head and neck areas, the pleuropulmonary system, and the abdominal cavity. We report a case of tubo-ovarian abscess caused by B. gracilis. A literature search revealed no previous reports. Our patient, a 29-year-old woman, experienced fever and lower abdominal pain caused by a tubo-ovarian abscess. Her treatment consisted of surgical drainage and prolonged intravenous antibiotic therapy. Initial therapy with cefotaxime and metronidazole failed and she remained febrile after the laparotomy. Her clinical condition improved slowly after initiation of imipenem therapy. Culture of a pus specimen obtained during surgery yielded B. gracilis, which was resistant to imipenem but susceptible to clindamycin. Combination therapy with imipenem and clindamycin was then administered and she recovered completely. Clindamycin was subsequently prescribed for long-term bacterial suppression. The potential difficulties in treating B. gracilis infections were a major clinical concern in the treatment of this patient.

Microcalorimetric Studies of the Interactions of Lysozyme with Immobilized Cu(II): Effects of pH Value and Salt Concentration

In this investigation, employing a highly sensitive microcalorimeter, we measure the influence of pH value and salt concentration on the heat of interaction between lysozyme and CS-IDA-Cu(II) gel. The direct enthalpy measurement of the interaction provides thermodynamic information regarding the binding behavior of lysozyme toward the immobilized metal ion. The binding enthalpy altered by adsorbed lysozyme at various pH values and salt concentrations are measured. The findings, along with the reported binding isotherm, are discussed herein.

Reactivation of silenced, virally transduced genes by inhibitors of histone deacetylase

Retroviral and adeno-associated viral sequences can dramatically silence transgene expression in mice. We now report that this repression also occurs in stably infected HeLa cells when the cells are grown without selection. Expression of a transduced lacZ gene (rAAV/CMVlacZ) is silenced in greater than 90% of cells after 60 days in culture. Surprisingly, high-level expression can be reactivated by treating the cells with sodium butyrate or trichostatin A but not with 5-azacytidine. When cell clones with integrated copies of rAAV/CMVlacZ were isolated, lacZ expression was silenced in 80% of the clones; however, lacZ expression was reactivated in all of the silenced clones by treatment with butyrate or trichostatin A. The two drugs also reactivated a silenced globin gene construct (rAAV/HS2alphabetaAS3) in stably infected K562 cells. Trichostatin A is a specific inhibitor of histone deacetylase; therefore, we propose that hyperacetylation of histones after drug treatment changes the structure of chromatin on integrated viral sequences and relieves repression of transduced genes. The reactivation of silenced, transduced genes has implications for gene therapy. Efficient viral gene transfer followed by drug treatment to relieve suppression may provide a powerful combination for treatment of various genetic and infectious diseases.

Liver and kidney growth hormone (GH) receptors are regulated differently in diabetic GH and GH antagonist transgenic mice

Elevated GH levels are frequently seen in poorly controlled type I diabetics and have been implicated in diabetic complications. Studies of GH and GH antagonist (GHA) transgenic mice with streptozotocin (STZ)-induced diabetes have revealed that GH has a permissive effect for diabetic nephropathy, and that expression of a GHA gene protected mice against diabetic kidney lesions. To investigate whether kidney GH receptor (GHR) and/or GH-binding protein may play a role in diabetic nephropathy, we evaluated GH-specific binding and messenger RNA levels for GHR/GH-binding protein in mouse livers and kidneys from bovine (b) GH or bGHA transgenic (Tg) mice and their nontransgenic (NTg) littermates with or without STZ-induced diabetes. We found that liver-specific GH binding is significantly higher in both bGH- and bGHA-Tg mice compared to that in their NTg controls. In contrast, kidney GH binding is significantly lower in bGH-Tg mice compared to that in NTg littermates. These results indicate that regulation of mouse GHR expression is tissue specific. STZ-induced diabetes decreased GH-specific binding in both liver and kidney of NTg and GHA-Tg mice, but not in bGH-Tg mice. The lowered GHR binding in diabetic NTg and GHA-Tg mice suggests the involvement of insulin in the regulation of GHR expression. The down-regulation of kidney GHR in GHA-Tg mice in combination with the presence of GHA may partially explain the protective mechanism of GHA against diabetic kidney lesions.

Differential expression of glomerular extracellular matrix and growth factor mRNA in rapid and slowly progressive glomerulosclerosis: studies in mice transgenic for native or mutated growth hormone

We found that mice transgenic for native bovine growth hormone (bGH) gene had increased body size and rapidly progressive glomerulosclerosis, whereas mice transgenic for a mutated bGH gene (bGH-m11) had near normal body size and slowly progressive glomerulosclerosis. The aim of this study was to determine whether rapidly and slowly progressive glomerulosclerosis had distinct glomerular extracellular matrix (ECM) and growth factor mRNA levels. ECM and growth factors were quantitated by competitive reverse transcriptase-PCR in microdissected glomeruli from bGH, bGH-m11, and nontransgenic littermate control mice. In rapid progressors (bGH mice) at 2 to 3 months, the levels of mRNA-coding for some glomerular ECM and growth factors were increased (alpha 1(IV) collagen, 7.3-fold; laminin B1, 3.9-fold; tenascin, 8-fold; and tumor growth factor (TGF)-beta 1, 3.4-fold). These levels underwent a further 2.3-fold increase at 6 to 9 months. Platelet-derived growth factor (PDGF)-B mRNA was high at 2 to 3 months (7.4-fold) and 6 to 9 months (9.5-fold) and was associated with an increased [3H]-thymidine-labeling index and glomerular cell number. In slow progressors (bGH-m11 mice), the mRNA levels at 2 to 3 months were approximately one half that of rapid progressors (alpha 1(IV) collagen, 3.4-fold; laminin B1 1.9-fold; tenascin, 3-fold; TGF-beta 1, 2.2-fold). PDGF-B levels were normal. At 6 to 9 months, alpha 1(IV) collagen, TGF-beta 1, and PDGF-B mRNA levels doubled, whereas tenascin and laminin B1 levels remained stable. At 12 to 18 months, the alpha 1(IV) collagen, TGF-beta 1, and tenascin levels increased by nearly another 50%. The labeling index and PDGF levels were not increased at any time. The levels of expression of several glomerular ECM mRNA and growth factors of rapid progressors at 2 to 3 months of age was nearly double that of slow progressors, nearly doubling again by 6 to 9 months. In slow progressors, alpha 1(IV) collagen and TGF-beta 1 mRNA levels continued to increase at a slow rate, but tenascin and laminin mRNA levels were only further increased at 12 to 18 months. Thus, the initial levels of these mRNA and their rate of change correlated with the severity of glomerulosclerosis.

Early postnatal dexamethasone therapy may lessen lung inflammation in premature infants with respiratory distress syndrome on mechanical ventilation

Early postnatal use of dexamethasone has recently been shown to be effective in improving the pulmonary status in premature infants with respiratory distress syndrome (RDS). To study the effect of dexamethasone on pulmonary inflammatory responses, we studied ten infants treated with dexamethasone and ten infants without this treatment. Serial tracheal aspirates were obtained for cell counts, neutrophil counts, total protein concentrations, and leukotriene B4 (LTB4) and 6-keto prostaglandin (PG)F(1 alpha) levels before and after starting the study. Infants in the dexamethasone-treated group required significantly lower mean airway pressures for ventilation and had lower PaCO2 values from day 3 to day 14 than infants in the control group, suggesting better pulmonary function. For infants in the dexamethasone group, the tracheal aspirates showed significantly lower cell and neutrophil counts, protein concentrations, and 6-keto-PGF(1 alpha) and LTB4 levels than in the control group. We conclude that early postnatal dexamethasone therapy may lessen lung inflammation and improve pulmonary function in infants with RDS.

Effect of diethylmaleate on liver extracellular glutathione levels before and after global liver ischemia in anesthetized rats

Glutathione (GSH), present in a high concentration in the liver, serves important protective functions. We investigated the effect of lowered tissue GSH content, accomplished by diethylmaleate (DEM) administration, on liver extracellular GSH levels before and after global ischemia in anesthetized rats. Liver extracellular GSH levels were determined by microdialysis perfusion and an on-line high performance liquid chromatography system. Global liver ischemia was induced by ligation of the hepatic pedicles including the hepatic artery, portal vein, and bile duct. DEM (4 mmol/kg) significantly lowered both the liver tissue GSH levels (1.36 +/- 0.26 micromol/g wet wt vs 9.50 +/- 0.55 micromol/g wet wt for the untreated) and the liver extracellular GSH levels (4.3 +/- 2.4 microM vs 25.2 +/- 8.7 microM for the untreated). Global liver ischemia induced a dramatic increase in the liver extracellular GSH level. Although the liver tissue GSH level was lowered following DEM treatment, DEM administration did not affect significantly ischemia-induced elevation of extracellular GSH (when presented as fold increase relative to basal value). In conclusion, DEM showed a direct effect on liver extracellular GSH content in anesthetized rats. However, DEM treatment did not affect the relative release of GSH following global liver ischemia.

Co-expression of bovine growth hormone (GH) and human GH antagonist genes in transgenic mice

Bovine growth hormone (bGH) transgenic (Tg) mice have been shown to possess enhanced growth phenotypes and exhibit severe glomerulosclerosis. One amino acid substitution in GH, i.e. G119R in bGH or G120R in human (h) GH, results in GH antagonists (GHAs). GHA-Tg mice exhibit dwarf phenotypes and normal kidneys. In order to investigate the possibility of GHAs as pharmaceutical agents for the treatment of human diseases with excessive GH levels, we cross bred mice that express bGH with those that express hGHA. Double positive Tg mice were identified that express both genes although at different levels. Kidney histological studies revealed that the double positive Tg mice with high GHA/GH expression ratios possessed normal or near normal kidneys, whereas those with low GHA/GH ratios exhibited glomerulosclerosis similar to GH-Tg mice. Thus, co-expression of GH and GHA genes in vivo results in animal phenotypes and kidney histopathologies which are a reflection of the relative expression levels of each gene.

Revised cutoff values of serum aminotransferase in detecting viral hepatitis among CAPD patients: experience from Taiwan, an endemic area for hepatitis B

BACKGROUND

To determine the best cutoff values of aspartate aminotransferase (AST) and alanine amino-transferase (ALT) in detecting viral hepatitis C infection among patients of continuous ambulatory peritoneal dialysis (CAPD).

METHODS

90 (44 male and 46 female) CAPD patients and 526 adult controls (266 male, 260 female) were enrolled. Serum AST and ALT were measured by an auto-analyser monthly. Serum HBsAg was examined using a RIA method and anti-HCV by an second-generation EIA method. The best cutoff values of AST and ALT for detecting viral hepatitis were obtained from the ROC (receiver-operating characteristic) curve.

RESULTS

The prevalence of anti-HCV(+) was significantly higher in CAPD patients (16.7%) than in normal controls (4.9%), while that of HBsAg(+) was similar in both groups. CAPD patients had significantly lower levels of serum aminotransferases compared to normal controls. Mean AST were 23.8 IU/l in normal control and 18.8 IU/l in the CAPD patients (P < 0.001). Mean ALT were 21.9 IU/l in normal controls and 15.3 IU/l in the CAPD patients (P < 0.001). CAPD patients with HCV infection had higher serum AST and ALT levels than those without. However, HBV infection did not cause significant serum aminotransferase elevation in patients. The conventional cutoff values of AST (40 IU/l) and ALT (40 IU/l) for detecting viral hepatitis yielded only a sensitivity of 27.3 and 18.2% respectively; on the contrary, our revised cutoff values of AST (24 IU/l) and ALT (17 IU/l) had better sensitivities (AST, 72.7%; ALT, 63.6%). For serial aminotransferase values, the sensitivity of AST and ALT for detecting HCV were 36.4 and 27.3% by conventional criteria, and were both 81.8%, by our newly revised criteria.

CONCLUSIONS

Serum aminotransferase cutoff values should be modified for screening viral hepatitis in a CAPD population. Our new cutoff criteria had important clinical implications in providing benefits of earlier detection and possible prevention from chronic hepatic deteriorations.

In vitro study of enzymatic degradation of biological tissues fixed by glutaraldehyde or epoxy compound

The study, using bacterial collagenase, was to investigate the changes in characteristics of a collagen-rich tissue, porcine pericardium, fixed by glutaraldehyde or epoxy compound (ethylene glycol diglycidyl ether) during the course of degradation. Fresh porcine pericardium was used as a control. During degradation, the heat released by the reaction of collagenase with a test sample was monitored by a highly sensitive microcalorimeter. Also, the degree of degradation of each test sample was determined by measuring its increment in free amino group content and changes in denaturation temperature and tensile strength. Microcalorimetric analysis of collagenase degradation of fresh, epoxy-fixed, and glutaraldehyde-fixed tissues revealed that the heat released during degradation correlates well with the degree of tissue degraded. The cleaving of peptide bonds in biological tissue by collagenase degradation may increase its free amino group content and reduce its denaturation temperature and tensile strength. It was noted that the fresh tissue cannot resist bacterial collagenase degradation, while the glutaraldehyde-fixed tissue had a relatively better resistance to degradation than its epoxy-fixed counterpart.

Viral hepatitis in continuous ambulatory peritoneal dialysis patients in an endemic area for hepatitis B and C infection: the Taiwan experience

The prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), and their associations in 64 continuous ambulatory peritoneal dialysis (CAPD) patients (30 males and 34 females) were evaluated. A comparison was also made with 526 normal controls (266 males and 260 females). Forty-seven (75%) CAPD patients were anti-HBc positive, with no significant difference to the control group (81.9%). This probably reflects acquisition of HBV infection by CAPD patients before initiation of chronic dialysis therapy in a region hyperendemic for HBV. On the contrary, 11 (17.2%) CAPD patients were anti-HCV positive and 8 (15.2%) were seropositive for both anti-HBc and anti-HCV-much greater prevalence rates compared to those of the control group. The prevalence of anti-HCV correlated with the history and numbers of blood transfusion, and the length of time on previous hemodialysis. A similar correlation occurred in patients with both anti-HBc(+) and anti-HCV(+). In conclusion, in an HBV endemic area such as Taiwan, the prevalence of coexisting HBV and HCV infection in CAPD patients depends on the latter.