Multicystic encephalomalacia in a surviving monochorionic twin

From a recent monochorionic diamniotic twin pregnancy seen at this hospital, one of the twins died in utero at 37 weeks' gestation. The other twin, a male infant, was delivered by Cesarean section because of fetal distress, with resuscitation performed in the delivery room. The infant developed generalized tonic seizure shortly after stabilization, and was put on anticonvulsants. The initial brain echography was normal; follow-up echograms and CT scans performed at 8 and 12 days old, respectively, revealed diffuse low density over both side of cerebral hemisphere. At one month old, the infants's brain echogram showed diffuse cystic encephalomalacia. At four months, he was noted to be spastic and significantly delayed in neurodevelopment. Disseminated intravascular coagulation caused by fetal-to-fetal transfer of thromboplastic material from the dead fetus was considered as the most possible cause of the neurological complication in this patient. In addition, perinatal hypoxic-ischemic insult may also have been a superimposed, influencing factor.

Association of HLA-DR14-DR52 with low responsiveness to hepatitis B vaccine in Chinese residents in Taiwan

To determine the HLA-linked immune response gene that controls low responsiveness to hepatitis B surface antigen (HBsAg), HLA typing was performed in 33 initial non-responders (male:female = 23:10, age 1.5-46 years) who had poor antibody response (anti-HBs < 10 mIU ml-1) after four doses of plasma-derived hepatitis B vaccine. Of 33 initial non-responders, 26 received two additional doses of either the same vaccine (n = 18) or recombinant hepatitis B vaccine (n = 8) and returned for anti-HBs measurement. At 1 month after the sixth dose, anti-HBs was still < 10 mIU ml-1 in 20 cases and 10-20 mIU ml-1 in three cases. Analysis of HLA antigen frequencies in these 23 ultimate low responders revealed that nine (39%) were positive for DR14, a statistically significant association of low responsiveness to hepatitis B vaccine with HLA-DR14. In addition, 26% of the ultimate low-responders were positive for DQ3, a frequency significantly lower than the expected rate in the general population. Among the nine ultimate low-responders with DR14, seven were heterozygous for this allele, while the other two cases had a single isolated DR14; and all nine were in association with DR52. These results suggest that a DR14-DR52 association, probably dominantly expressed, may be involved in the low immune responsiveness to hepatitis B vaccine of the Chinese population in Taiwan.

Bench-scale production of acrylamide using the resting cells of Brevibacterium sp. CH2 in a fed-batch reactor

Effects of various organic acids and salts on the stabilization of nitrile hydratase were investigated. The stability of the nitrile hydratase of Brevibacterium CH2 during storage was greatly enhanced by the addition of n-butyric acid. Effects of temperature, pH, and concentrations of acrylonitrile and n-butyric acid on acrylamide production by the resting cells were also investigated. Acrylamide production per unit dry weight of the cells increased 1.33 times by the addition of 0.05% n-butyric acid. A 20% acrylamide solution was successfully produced in a bench-scale reactor (12 l) with only a trace amount of salts after 10 h of hydration reaction under optimum reaction conditions without using an isotonic substrate. The conversion yield was nearly 100%, and acrylic acid as a by-product was not produced. Final acrylamide production of 400 g g-1 cells and productivity of 20 g/(g cells l-1 x h-1) were obtained.

Histologic and ultrastructural features of experimental duodenal ulcers in Sprague-Dawley rats

The histologic and ultrastructural features of a time sequence study of the development, evolution, and healing of acetic acid-induced experimental duodenal ulcer are presented. Duodenal ulcers produced by serosal application of acetic acid featured microvascular injury with progressive disintegration of the tips of the mucosal villi and subtotal necrosis of the duodenal wall. At 3 days ulcers transformed into a chronic state with regenerating epithelium originating from the crypts of the intact bordering mucosa extending toward the center of the ulcers. By 21 days healed ulcers were covered by distorted duodenal surface mucosa. We conclude that this reproducible and standardized model of duodenal ulcer features vascular injury as the earliest microscopic event, that ischemic necrosis leads to ulceration, and that the chronic phase bears morphologic resemblance to human duodenal ulcer.

Insulin and intestinal epithelial cell proliferation

The effects of modification of the levels of endogenous plasma insulin on intestinal epithelial cell proliferation were investigated in rats maintained by total parenteral nutrition (TPN) using either a TPN diet that was high in glucose, or a low glucose (hypocaloric) TPN diet and in orally fed rats (normal and sham operated). The rats were put on their respective treatments for 7 days and were then injected with vincristine sulphate to arrest cells as they entered metaphase. Intestinal tissue was fixed for the determination of crypt cell production rate (CCPR) and blood plasma was taken for hormone radioimmunoassay. Sham operation had no effect on either plasma hormone levels or on CCPR. The standard TPN diet was associated with significantly reduced levels of gastrin, peptide YY and enteroglucagon. Gastrin and PYY were further reduced by the hypocaloric diet. However, plasma insulin was much increased in the TPN but not in the hypocaloric group. Small intestinal CCPR was reduced in the TPN groups, but no difference was observed between the standard and the low calorie TPN diets. The lack of difference in CCPR between the two TPN diets despite the massive elevation of plasma insulin strongly suggests that insulin does not have a substantial role in the control of gastrointestinal epithelial cell renewal.

Persistent pulmonary hypertension of the newborn associated with excessive pulmonary arterial muscularization: report of an autopsy case

A 3700-g male infant born at 37 weeks' gestation presented with cyanosis at birth. He was diagnosed as having persistent pulmonary hypertension of the newborn (PPHN) on the basis of persistent hypoxemia, despite continuous mechanical ventilatory support with 100% O2, and right-to-left shunting through the foramen ovale shown by Doppler echocardiography. Treatment with hyperventilation, and administration of tolazoline, prostaglandin E1 and MgSO4 failed to reverse his hypoxemia. High ventilator settings were required, and pneumothoraces ensued. Airway resistance increased gradually with development of hypercapnia and deterioration of hypoxemia. Bradycardia unresponsive to resuscitation occurred, and he died at eight days of age. Postmortem examination of the lungs revealed increased peripheral connective tissue and diffuse extension of medial smooth muscle to the precapillary pulmonary arteries. Excessive antenatal muscularization of the peripheral pulmonary arteries and resultant increased vasoconstriction capacity may have played an important role in the pathogenesis of PPHN in this case.

Minimal role of hepatitis C virus infection in childhood liver diseases in an area hyperendemic for hepatitis B infection

To investigate the role of hepatitis C virus (HCV) in childhood liver disease in Taiwan, an area hyperendemic for hepatitis B, we studied antibody to HCV (anti-HCV) with a second generation enzyme immunoassay in 195 infants and children, including 96 hepatitis B surface antigen (HBsAg) positive children (66 with chronic hepatitis B, 23 children with hepatocellular carcinoma, and 7 with fulminant hepatitis B), 6 children with fulminant non-A, non-B hepatitis, 42 infants with neonatal hepatitis, 11 with biliary atresia, and 40 prospectively followed blood recipients. For comparison, another 748 apparently healthy children (from neonates to 12 years) were also screened for anti-HCV. The positive rate of anti-HCV was low in both apparently healthy children (0.13%) and patients with various liver disorders (0 to 4.4%) except fulminant hepatitis. The seropositive rate in 6 cases of non-A, non-B fulminant hepatitis was higher (16.7%) although the case number was too small. We conclude that HCV is generally not a major etiologic factor in the liver diseases of Taiwanese children.

Molecular identity of a sperm acrosome antigen recognized by HS-63 monoclonal antibody

The molecular identity of mouse sperm acrosome antigen recognized by HS-63 monoclonal antibody was analyzed by various biochemical, immunological and molecular biological methods. When its cognate antigen, MSA-63 was isolated from mouse testis by immunoaffinity chromatography, a group of protein spots with wide range of molecular sizes and isoelectric points were identified. Through previous studies, it was established that most of these protein spots were actin-like molecules co-purified with MSA-63 protein from mouse testis. To analyze the molecular size heterogeneity of the isolated MSA-63 proteins, rabbit antisera against a computer-predicted antigenic synthetic peptide (amino acid residue No. 160-171) and a recombinant glutathione S-transferase (GST) fusion protein (GST-63) were raised. These two antisera and those raised against the isolated MSA-63 protein were used as the probes in comparative Western blot assay, indirect immunofluorescent assay and enzyme-linked immunosorbent assay (ELISA). Using ELISA, antisera against GST-63 and computer-predicted antigenic synthetic peptides were shown to cross-react with affinity-isolated MSA-63 protein coated on microwells. However, little immunological cross-reactivity was observed between GST-63 fusion protein and the synthetic peptide. By using a Western blot assay, two major protein bands of 22 and 32 kDa, respectively were commonly detected on mouse testis homogenate strips by both anti-MSA-63 and anti-GST-63. In addition, anti-MSA-63 also recognized several protein bands with molecular masses greater than 35 kDa. The results of this study suggested that the molecular heterogeneity of MSA-63 protein isolated from mouse testis and sperm, is due to a series of post-translational modifications on a single gene product. These modifications may include glycosylations, proteolytic digestions and tight non-covalent associations with other testicular cytoskeletal proteins, such as actins.

The gene convergent to luxG in Vibrio fischeri codes for a protein related in sequence to RibG and deoxycytidylate deaminase

The nucleotide sequence of a convergent gene with the same bidirectional transcriptional terminator as the Vibrio fischeri lux operon has been determined. This gene codes for a polypeptide of 147 amino acids which is related in sequence to the polypeptide coded by the first gene (ribG) of the rib operon of Bacillus subtilis as well as deoxycytidylate deaminase of T4 bacteriophage and Saccharomyces cerevisiae. These results raise the possibility of a linkage between the regulation of the lux genes and riboflavin synthesis in Vibrio fischeri.

Safety and immunogenicity of hepatitis A vaccine in healthy adult volunteers

The immunogenicity and adverse reaction of an inactivated hepatitis A (HA) vaccine were investigated. Sixty healthy adult volunteers who lacked antibody to HA virus (anti-HAV) received three doses of vaccine containing 720 enzyme-linked immunosorbent assay (ELISA) units (EL.U) according to a 0, 1 and 6 month schedule. Blood tests for serum liver enzymes and anti-HAV were performed at screening 7 days prior to, and 1, 6 and 7 months after the first dose. Anti-HAV was tested by radio immunoassay and ELISA for titre determination. The seroconversion rates measured by ELISA were 98.3% (59/60) at months 1 and 6 and 100% at month 7. Sixty-one per cent (109/180) of the documented injections were followed by local symptoms, essentially mild soreness at the site of injection; and 22.2% (40/180) by minor general symptoms including malaise, fatigue and lethargy. It is concluded that HA vaccine is highly immunogenic and safe. It may replace immunoglobulin as an effective method of preventing HA virus infection in adults.

Electron microscopic immunolocalization of a conserved sperm acrosomal antigen recognized by HS-63 monoclonal antibody

HS-63 monoclonal antibody was shown to react with a sperm-specific acrosomal antigen from spermatozoa of a variety of mammalian species. Indirect immunofluorescence showed that HS-63 was associated with acrosome-intact sperm after sperm had been fixed with methanol. Electron microscopy (EM) was employed to determine the ultrastructural localization of this sperm antigen. When the immunogold labelled goat anti-mouse IgG was used as a probe, we demonstrated that HS-63 monoclonal antibody did not bind to the freshly prepared human spermatozoa. However, gold particles were observed in the intra-acrosomal region, when the spermatozoa had been pre-treated with 0.5% Triton X-100 prior to incubation with HS-63. We further observed that the immunogold did not stain the inner acrosome membrane when the spermatozoa became acrosome-reacted. A good correlation was obtained between the percentage of spermatozoa which did not react with HS-63 as determined by indirect immunofluorescence assay and that of acrosome-reacted spermatozoa as quantitated by electron microscopy. The results of this EM study were consistent with those obtained by indirect immunofluorescence assay and both indicated that HS-63 reacts only with the capacitated and acrosome-intact spermatozoa. Therefore, HS-63 monoclonal antibody is a useful probe for rapid evaluation of acrosomal status in human spermatozoa.

Effects of hyperthermia on the nucleolar proteins in tumour cells

The effects of hyperthermia at 41 degrees C and 43 degrees C on the nucleolar protein B23 in Ehrlich ascites tumour (EAT), human glioblastoma U-87 MG and U-373 MG cell lines were studied. Cellular localization of protein B23 was detected by an immunofluorescence technique using monoclonal antibody against protein B23. Diminution of fluorescence in the nucleoli occurred when the cells were treated at high temperature. The decrease in fluorescence level depends on the treatment temperature and duration. Among the three cell lines studied, the U-373 MG glioblastoma was the least responsive to hyperthermia followed by the U-87 MG glioblastoma. The decrease in nucleolar fluorescence of the EAT cells treated at 41 degrees C and 43 degrees C correlated with their subsequent cell survival. Dispersion of the nucleolar argyrophilic granules occurred in EAT cells after heating at 43 degrees C for 1 h. The possible implication of such effect is discussed in relation to the heat-sensitive elements in the nucleolus.

Depletion of alveolar macrophages by liposome-encapsulated dichloromethylene diphosphonate

Alveolar macrophages (AM) play an important role in lung biology. In this study, we demonstrated that tracheal insufflation of liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP-liposome) selectively depleted AMs in rats. Insufflation of a single dose of Cl2MDP-liposomes (80 microliters containing 1.34 mumol of Cl2MDP) but not liposomes containing phosphate-buffered saline resulted in > 70% depletion of AMs starting within 1 day and lasting for > 5 days after insufflation. There was a slight but significant intraalveolar inflammatory response. Insufflation of Cl2MDP also resulted in depletion of AMs; however, it caused cytoplasmic edema of alveolar epithelial cells as well. Depletion of AMs by Cl2MDP-liposomes markedly reduced the endotoxin-induced neutrophil (polymorphonuclear lymphocyte) recruitment and the release of tumor necrosis factor into the alveolar space, suggesting that endotoxin-induced neutrophil recruitment and tumor necrosis factor release were dependent on AMs. This AM-depleted animal model will be useful for studying the in vivo functions of AMs and their role in various physiological and pathological conditions.

Expression of components of the insulin-like growth factor system in pig mammary glands and serum during pregnancy and pseudopregnancy: effects of oestrogen

To gain insight into the involvement and interactions of the insulin-like growth factors (IGFs) and estrogen in mammary growth and differentiation, the temporal expression of mammary mRNAs encoding components of the IGF system in pregnant and pseudopregnant pigs was examined. Pseudopregnant pigs received 5 mg oestradiol valerate or vehicle daily from day 45 after oestrus and underwent mammary biopsy on days 60, 90 or 112. In mammary tissue of pregnant pigs, steady-state levels of the mRNAs encoding IGF-I, IGF-II and type-I IGF receptor as well as the levels of the membrane-associated type-II IGF receptor were higher during the early phase of mammogenesis (< or = day 45) than during the subsequent stages of mammary development. Mammary IGF-I, IGF-II and type-I receptor mRNAs were expressed at their lowest levels around day 90 of pregnancy (20-40% of those for day 30 of pregnancy) coincident with the onset of beta-casein mRNA accumulation. Mammary IGF-binding protein-2 (IGFBP-2) mRNA levels increased twofold during the latter half of pregnancy, whereas the amount of IGFBP-3 mRNA declined after day 30 to undetectable levels by mid-pregnancy. Pseudopregnant pigs had reduced levels of these mRNAs (except for IGF-II) relative to their pregnant counterparts and this was associated with premature differentiation of mammary tissue as reflected by an earlier onset of beta-casein mRNA accumulation in the former. The administration of oestradiol valerate decreased the levels of IGF-I and type-I IGF receptor mRNAs by day 60 of pseudopregnancy, but the reverse was evident by day 112. Oestradiol administration increased beta-casein mRNA levels in pseudopregnant pigs, but had no effect on mammary IGFBP-2 and IGFBP-3 mRNA levels. Mammary IGF content was greater in late pregnancy (> or = day 90) and pseudopregnancy than at early pregnancy. Serum IGF-I and IGF-II levels declined steadily during pregnancy and this was similar to, but not correlated with, mammary IGF mRNA levels, whereas in pseudopregnant pigs, serum IGF concentrations did not change temporally or in response to oestradiol. Serum IGFBP-2 levels were unaltered during pregnancy or pseudopregnancy, but serum IGFBP-3 levels declined after day 60 of pregnancy. In pseudopregnant pigs, serum IGFBP-3 levels did not change temporally, but declined after oestradiol treatment. Results indicate that mammary IGF-I and type-I IGF receptor systems are down-regulated during pregnancy-associated differentiation of this tissue and in response to oestrogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Safety and immunogenicity of hepatitis A vaccine in healthy children

The immunogenicity and reactogenicity of an inactivated hepatitis A (HA) vaccine in children were investigated. One hundred three healthy children who lacked antibody to HA virus (anti-HA virus), aged between 3 months and 6 years 8 months, were enrolled in this study. They received three doses of 360 enzyme-linked immunosorbent assay units of HA vaccine in a 0-, 1- and 6-month schedule. Blood tests for aminotransferase and anti-HA virus were performed 7 days before and 1, 6 and 7 months after the first dose. Anti-HA virus was tested by radioimmunoassay and also by enzyme immunoassay for titer determination. The seroconversion rates measured by enzyme immunoassay were 95.1% (98 of 103) at Month 1 and 100% at Months 6 and 7. Nine percent (28 of 309) of the injections were followed by local symptoms, usually mild soreness and swelling at the site of injection, and 12% (37 of 309) by minor general symptoms. We conclude that HA vaccine is highly immunogenic and safe in children. It may replace immunoglobulin as an effective method to prevent HA virus infection in children. We also suggest that the HA vaccine be administered to children in endemic areas.

Ontogeny of the porcine insulin-like growth factor system

The developmental expression of the individual components of the insulin-like growth factor (IGF) system in pigs was examined. Serum IGF-I and IGF-binding protein-3 (IGFBP-3) levels were low during fetal life and increased during postnatal development. Levels of mRNAs encoding these proteins were not greater for liver than for nonhepatic tissues (skeletal muscle, lung, kidney) and did not increase during the postnatal period, whereas hepatic growth hormone (GH) receptor mRNA expression was increased postnatally. Serum IGF-II levels exceeded IGF-I levels at all developmental stages examined and both exhibited postnatal increases. IGF-II mRNA abundance, in contrast, was high in the fetal tissues with the exception of lung and declined during the perinatal transition. Hepatic IGFBP-2 mRNA and serum IGFBP-2 levels increased during the latter half of gestation and then declined postnatally. The levels in muscle and liver of type I IGF receptors and the corresponding mRNAs also exhibited postnatal decreases. The discordance of changes in hepatic IGF-I and IGF-II mRNA abundance with serum IGF levels during the postnatal period does not support the concept that liver is the primary endocrine source of IGFs in the young pig. The postnatal increases in serum IGF levels may reflect decreased plasma clearance rates of these peptides which may be related to the transition in IGFBP type from IGFBP-2 to IGFBP-3 in blood and the reduced tissue expression of IGF receptors.

Metabolic profile of patients after elective open heart surgery

To evaluate the surgical stress of open heart surgery with moderate hypothermic cardiopulmonary bypass (CPB), oxygen consumption (VO2), carbon dioxide production (VCO2), resting energy expenditure (REE), respiratory quotient (RQ), 24 hour-urinary urea nitrogen excretion (UUN), and glucose, fat and protein utilization were determined in 20 patients before and after open heart surgery. Proteins (albumin, prealbumin and transferin) and body weight were measured preoperatively and on 6th postoperative day (POD). Preoperative predicted EE as determined by the Harris-Benedict equation was correlated with measured REE. No significant alteration in VO2, VCO2, REE, 24 hour UUN and protein utilization was observed on the first 6 PODs. RQ decreased significantly on the 1st, 3rd and 4th POD. This was attributed to greater fat utilization due to reduced calorie intake during the early postoperative period. Transport proteins reduced slightly but insignificantly. There was a significant reduction in body weight at the end of the study period due probably to loss of body water. We conclude that patients in the early postoperative period after uneventful open heart surgery are neither hypermetabolic nor hypercatabolic when compared with their stable state before operation.

Primary infections of Epstein-Barr virus, cytomegalovirus, and human herpesvirus-6

A total of 121 infants entered a cohort serological study of primary infections with herpes-viruses. All of them had seven samples of blood available: the first sample was taken soon after birth, the other six were taken at 1, 2, 3, 6, 12, and 14 months of age. One sample of maternal blood was collected immediately after delivery. All blood samples were tested for antibodies against cytomegalovirus, Epstein-Barr virus, and human herpesvirus-6 (HHV-6). Primary cytomegalovirus infection occurred early; the cumulative infection rates were 1.7%, 8.3%, 18.3%, 25%, 52.5%, and 65% by the ages of 1, 2, 3, 6, 12, and 14 months, respectively. Epstein-Barr virus infection was not seen before 3 months of age and slowly emerged thereafter, reaching a cumulative rate of 1.7%, 11.6%, 21.5% at the ages of 6, 12, and 14 months, respectively. Primary HHV-6 infection was also a rare event in the first three months of life, but peaked between 6 and 12 months of age. No detectable risk factors were associated with primary Epstein-Barr virus or HHV-6 infection. The risk factors associated with cytomegalovirus infection included breast feeding, fewer children in household, and care by a babysitter.

Protein kinase C as a multi-targeted feedback inhibitor regulating the Ca2+ responses to chemotactic peptide stimulation in the murine macrophage cell line PU5-1.8

The role of protein kinase C (PKC) in the signal transduction process when macrophage cells were stimulated by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) was investigated in the cell line PU5-1.8. Addition of fMLP to PU5-1.8 cells induced a rapid generation of inositol trisphosphate and a translocation of PKC. Concomitantly there was an influx of Ca2+ followed by its expulsion. PKC was likely involved in Ca2+ extrusion as short-term pretreatment of cells with phorbol 12-myristate 13-acetate (PMA) enhanced the removal of preloaded 45Ca2+ but had no significant effect on fMLP-stimulated 45Ca2+ influx. Depletion of cellular PKC activity through down-regulation or exposure of cells to PKC inhibitors also blocked the fMLP-stimulated 45Ca2+ efflux. Further experiments using PMA revealed that PKC also decreased vesicular Ca2+ and stimulated the catabolism of inositol 1,4,5-trisphosphate. These results lend support to the notion that PKC serves as a negative feedback modulator in Ca2+ signalling and further suggest that it operates at several target sites.

Evaluation of a proposed technique to assess unscheduled DNA synthesis and genotoxicity

Results from a recent, new assay suggest that omeprazole, a potent inhibitor of gastric acid secretion, is genotoxic. The principle of this assay is that the non-proliferating zone of surface gastric epithelial cells can be selectively removed by controlled digestion so that any incorporation of tritiated thymidine into these cells represents unscheduled DNA synthesis. Parietal cells (which are located below the uppermost proliferating cells) and proliferating cells in semiconservative, regular DNA synthesis could always be shown in the digested fraction, and as regular DNA synthesis takes up a thousand fold more thymidine than unscheduled DNA synthesis, any signal from unscheduled synthesis would therefore be swamped. The digestion process was also uneven, as histological analysis showed denuded patches of mucosa, and gland like structures were seen in the digest. Quantification of the number of silver grains over the nuclei showed no increase in low level labelling after omeprazole administration, indicating that there was no unscheduled DNA synthesis. The labelling index of undigested gastric tissue from omeprazole treated rats was not significantly different from that of the control group, despite an increase in the plasma gastrin value.

Absence or delayed appearance of hepatitis B core antibody in chronic hepatitis B surface antigen carrier children

An absence of the hepatitis B core antibody (anti-HBc) in hepatitis B surface antigen (HBsAg) carrier children has been reported before, but whether anti-HBc will ultimately appear is unknown. In a group of 420 HBsAg carrier children who were followed longitudinally, 10 (2.4%) had an absence or delayed appearance of serum anti-HBc. These 10 children were persistently seropositive for HBsAg, hepatitis B e-antigen, and hepatitis B virus DNA (HBV-DNA). Anti-HBc never appeared in 4, one of whom was a case of hepatitis B vaccine failure and became an HBsAg carrier. Three of the 4 were born to HBsAg carrier mothers. Liver biopsy in one revealed non-specific reactive hepatitis (NSRH). All 4 were asymptomatic during follow-up. Mothers of the other 6 children who had delayed appearance of anti-HBc were also HBsAg carriers. The children seroconverted to anti-HBc positivity between 2 and 8 years of age, and the titer of serum anti-HBc at the first appearance varied. There were no significant changes in liver function tests, HBV-DNA levels, or associated symptoms and signs before and after seroconversion. Liver biopsies were performed before anti-HBc seroconversion in 2 children and showed NSRH. All 10 children had a moderate to high replication of HBV as shown by the high titer of HBsAg and HBV-DNA. The absence of anti-HBc occurred almost exclusively in children who were infected perinatally.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning, sequencing, and genetic characterization of regulatory genes, rinA and rinB, required for the activation of staphylococcal phage phi 11 int expression

The int gene of staphylococcal bacteriophage phi 11 is the only viral gene responsible for the integrative recombination of phi 11. To study the regulation of int gene expression, we determined the 5' end of the transcript by S1 mapping. The presumed promoter is located just 22 nucleotides upstream of the int open reading frame in a region which is conserved between phi 11 and a closely related staphylococcal phage, L54a. To clone the possible regulatory gene, a vector which contained the reporter gene, xylE, of Pseudomonas putida under the control of the phi 11 int promoter was constructed. Subsequently, a 2-kb DNA fragment from the phi 11 genome, which mapped distal to the int gene, was shown to increase the XylE activity from the int promoter. Sequencing and subsequent deletion analysis of the 2-kb fragment revealed that two phi 11 regulatory genes, rinA and rinB, were both required to activate expression of the int gene. Northern (RNA) analysis suggested that the activation was, at least partly, at the transcriptional level. In addition, one of these regulatory genes, rinA, was capable of activating L54a int gene transcription.

Change of membrane potential is not required for the tumour necrosis factor-alpha mediated cytotoxicity

Recent evidence has been demonstrated that trimeric tumour necrosis factor-alpha (TNF) itself is a channel forming molecule and incubation of TNF with TNF-sensitive tumour cell line U937 increases the plasmalemmal Na+ permeability (21). Therefore, membrane potential (Em) may play a role in the cytotoxicity mediated by TNF. Results in our study demonstrate that: 1) TNF did not induce any changes of Em of L-929 cells but gramicidin and valinomycin produced positive responses as measured by two fluorescent probes, bis-oxonol and dis-C3-(5). 2) Exogenously imposed membrane depolarization by gramicidin or high potassium buffer did not attenuate the TNF-mediated cytotoxicity in L929 cells. 3) When the Em of L-cells was clamped at K(+)-equilibrium potential, TNF showed a dose-dependent cytotoxicity (determined by cell morphology and neutral red uptake assay) which was very similar to the normal TNF cytotoxic action. Taken together, evidence in our study illustrates that membrane depolarization or hyperpolarization is not required for TNF-mediated cytotoxicity.