Biomedical subjects

J Zhu

Publications and source records attributed to J Zhu.

At least 703 records · Page 39Linked to original sources

PubMed1994

Comparison of the two major ARS elements of the ura4 replication origin region with other ARS elements in the fission yeast, Schizosaccharomyces pombe.

We have previously reported that the replication origin region located near the ura4 gene on chromosome III of the fission yeast, Schizosaccharomyces pombe, contains three closely spaced origins, each associated with an autonomously replicating sequence (ARS) element. Here we report the nucleotide sequences of two of these ARS elements, ars3002 and ars3003. The two ARS elements are located on either side of a transcribed 1.5 kb open reading frame. Like 11 other S. pombe ARS elements whose sequences have previously been determined in other laboratories, the 2 new ARS elements are unusually A+T-rich. All 13 ARS elements contain easily unwound stretches of DNA. Each of the ARS elements contains numerous copies, at a higher than expected frequency, of short stretches of A+T-rich DNA in which most of the Ts are on one strand and most of the As are on the complementary strand. We discuss the potential significance for ARS function of these multiple asymmetric A+T-rich sequences.

Base Composition↗

PubMed1994

Analysis of region-specific library constructed by sequence-independent amplification of microdissected fragments surrounding weaver (wv) gene on mouse chromosome 16.

The C3-C4 region of mouse chromosome 16 was microdissected and amplified directly by sequence-independent amplification (SIA). The SIA product was proved to originate from the microdissected region by fluorescence in situ hybridization (FISH) and was cloned into the PCR II vector (mean insert size 506 bp). Colony hybridization showed that about 59% of the clones contained either unique or low copy number sequences. Southern blot analysis of 100 unique clones demonstrated that 50 clones hybridized with single (33 clones) or multiple (17 clones) bands on blots of DNA from a hamster-mouse hybrid cell line that contains mouse chromosome 16, 13 clones hybridized with mouse but not with the hamster-mouse hybrid DNA, 19 clones contained repetitive sequences, and the remaining 18 clones failed to yield bands. One third of the 100 unique clones hybridized to human genomic DNA. Thirty-three clones were sequenced. None of them was found in GenBank. Our results demonstrate that this relatively simple method of microdissection and cloning can produce a library of good quality.

Animals↗

PubMed1994

The B cell repertoire in experimental allergic neuritis involves multiple myelin proteins and GM1.

Experimental allergic neuritis (EAN) is a T cell mediated disease associated with inflammation and demyelination of peripheral nerves. EAN is an experimental model of Guillain-Barré syndrome. The peripheral nerve myelin components P2 and P0 represent major neuritogens, but the diversity and quantity of B cell responses in EAN are unknown. Lewis rats were immunized with bovine peripheral nerve myelin (BPM), and levels of B cells secreting IgM and IgG antibodies to BPM, P2 and P0, the glycolipid GM1 and five peptides of myelin-associated glycoprotein (MAG) were determined. Already on day 7 post-immunization (p.i.), i.e. before the onset of clinical EAN, lymph nodes contained elevated levels of cells secreting IgM antibodies of all specificities examined. Maximum numbers of IgG antibodies secreting cells were generally reached at the height of clinical disease. The numbers of cells secreting IgG antibodies to BPM, P2, P0, GM1 and MAG peptides were also elevated before disease onset, but they were mostly higher than those of IgM antibodies and they reached their maximum only after recovery. The results imply that EAN is associated with strong B cell responses to all myelin antigens under study without restriction to any immunodominant myelin component or MAG peptides.

Amino Acid Sequence↗

PubMed1994

Establishing a resuscitation model in rabbits with closed-thoracic cardiopulmonary by-pass.

This study aims to establish an animal model of resuscitation in rabbits by using closed-thoracic cardiopulmonary by-pass (CTCPB). The rabbits were randomly divided into four groups according to cardiac arrest times which were 8, 10, 12, and 15 min. Neurologic outcome and blood lactate were determined within 150 min after resuscitation. It was indicated that the rabbits' neurologic functions were progressively injured with prolonged cardiac arrest time. The threshold of circulatory arrest time that induced a vegetative state in the rabbits was between 10 and 12 min. There were no significant differences in cardiac resuscitability among the four groups, as was so for plasma lactate, although it increased significantly from the control levels. The establishment of a small-animal model of resuscitation by using CTCPB, and the problems in dealing with it are also described and discussed in detail in this paper. Our experience indicated that this is a simple, convenient, and economical animal model for the study of resuscitation.

Animals↗

PubMed1994

Fabrication and characterization of glucose sensors based on a microarray H2O2 electrode.

A glucose sensor was recently developed by modifying an immobilized GOD (glucose oxidase) membrane and coating Nafion diffusion limiting membrane over an amperometric H2O2 MAE (microarray electrode), which was fabricated by using standard planar processing. The chip of the sensor is 2.5 mm by 15. The MAE is composed of an Ag/AgCl RE (reference electrode), a Pt CE (counter electrode) and two sets of Pt WE (working electrode), each set consists of five bands. Silicon nitride was chosen as the top insulator. Six MAEs different in both width and length of the band were examined and the MAE with the narrowest width (10 microns) of bands exhibits the best electrochemical performances. The glucose sensor based on the MAE B1-2 presents a linear range of 0.5-40 mM glucose at 37 degrees C with a 1/15 M phosphate buffer solution (pH = 7.0) as supporting electrolyte. The sensitivity, background current, response time, CV (coefficient of variation) and long-term stability of the sensor are 7.1 +/- 0.5 nA/mM, 2 +/- 0.5 nA, 30 s, 3.4% and 6 days respectively.

Biosensing Techniques↗

PubMed1994

The sequential effects of human cervical mucus, oviductal fluid, and follicular fluid on sperm function.

OBJECTIVE: To compare the sequential effects of human cervical mucus (CM), oviductal fluid, and follicular fluid (FF) on sperm motility, hyperactivation, and the acrosome reaction during 9 hours of incubation in vitro. DESIGN: Spermatozoa from a fertile donor were allowed to penetrate human CM in vitro and then were recovered and incubated in either 30% human oviductal fluid or a simple salt solution for 3 hours before challenge with 20% FF. Thus, the sequential effects of the fluids collected from the female reproductive tract on sperm hyperactivation and acrosome reaction were examined. SETTING: The donor insemination program at the University Clinic within the Jessop Hospital for Women, Sheffield, United Kingdom. PATIENTS: All donors used in this study were involved in the donor insemination program. MAIN OUTCOME MEASURES: Sperm motility, hyperactivation, and percentage of acrosome-reacted spermatozoa were measured. RESULTS: This study used an in vitro technique to mimic sperm transport in vivo. Spermatozoa sequentially incubated with female reproductive tract secretions in vitro showed a maintenance in the level of FF-induced hyperactivated motility and a decreased response to the FF-induced acrosome reaction when compared with sperm challenged with FF in the absence of prior incubation with human oviductal fluid. CONCLUSION: It is suggested that human oviductal fluid may serve to delay the FF-induced acrosome reaction.

Acrosome↗

PubMed1994

Rocuronium (Org 9426) for caesarean section.

This was a prospective, non-randomized, multicentre study of rocuronium (Org 9426) in 40 elective Caesarean section patients at full term without fetal distress. Anaesthesia was induced with thiopentone 4-6 mg kg-1 i.v. and rocuronium 0.6 mg kg-1 and maintained with isoflurane and nitrous oxide in oxygen. Monitors included ECG, arterial pressure, pulse oximeter and train-of-four (TOF) produced by ulnar nerve stimulation. In all patients, full neuromuscular block at the hand indicating the maximum effect of rocuronium (T1 = 0) occurred at a mean time of 98.1 (SE 9.4) s. However, after 79.3 (2.9) s, excellent to good intubating conditions were achieved in 90% of patients. Injection to delivery time was 12.7 (0.9) min and the surgical procedure lasted 53.1 (3.5) min. After administration of rocuronium, T2 appeared after 32.7 (1.8) min (indicating duration of effect). At the end of the surgical procedure in 39 patients, glycopyrronium 0.2 mg and neostigmine 1 mg were given every 5 min to antagonize residual neuromuscular effect. The mean dose of neostigmine required was 1.54 (0.1) mg. Rocuronium had no clinically significant effect on maternal heart rate or arterial pressure. After administration of thiopentone and rocuronium in two patients, temporary erythema occurred, one along the site of injection and the other on the chest wall. Rocuronium had no untoward effects on the neonates, evaluated by 1- and 5-min Apgar scores, time to sustained respiration, total and muscular neuroadaptive capacity scores, acid-base status and blood-gas tensions in umbilical arterial and venous blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Androstanols↗

PubMed1994

Ligand regulation of bovine protein kinase C alpha response via either cysteine-rich repeat of conserved region C1.

Based on the finding by others that the conserved region C1 of conventional protein kinase C isoforms carries two independent, cysteine-rich phorbol ester binding sites, we have mapped the structural elements of the C1 region for their role in the phorbol ester- and phospholipid regulation of PKC alpha responses. We have prepared two amino terminal truncation mutants of bovine PKC alpha, ND91 lacking the first Cys-repeat of C1, and ND153 lacking both Cys-repeats of C1, as well as two internal deletion mutants, D162-245 lacking most of C2, and D109-263 lacking most of C2 and the second Cys-repeat of C1. The mutants were expressed in the yeast Saccharomyces cerevisiae which allows the rapid biochemical and physiological characterization of mammalian PKC isoforms. We found that all mutants displayed an elevated basal level of enzymatic activity in vitro but retained the basic catalytic PKC characteristics: regulation by Ca2+ and (except for ND153) by phospholipid or phorbol ester. In vivo we observed proportional physiological responses, the stimulation of Ca2+ uptake, and an increase in the cell doubling time for all mutants upon phorbol ester stimulation (constitutive for ND153) similar to the response of normal PKC alpha. Our findings indicate that after partial PKC activation by deletion mutagenesis, the presence of either Cys-repeat in C1 still allows phospholipid- and phorbol ester regulation of protein kinase C alpha responses.

Animals↗

PubMed1994

Cellular mRNA expression of interferon-gamma, IL-4 and transforming growth factor-beta (TGF-beta) by rat mononuclear cells stimulated with peripheral nerve myelin antigens in experimental allergic neuritis.

Experimental allergic neuritis (EAN) serves as a useful model for inflammation in the peripheral nervous system. To study the potential role of important immunoregulatory and effector cytokines in EAN, we examined the expression of mRNA for interferon-gamma (IFN-gamma), IL-4 and TGF-beta by in situ hybridization in lymph node and splenic cells cultured with bovine peripheral nerve myelin (BPM), P2 and P0 during the course of EAN in Lewis rats. Levels of IFN-gamma mRNA-expressing mononuclear cells (MNC) from lymph nodes and spleens roughly correlated with clinical status, consistent with a disease-promoting role for IFN-gamma. BPM, P0 and P2-reactive IFN-gamma mRNA-expressing T cells appeared in lymph nodes and spleen before onset of the disease, whereas a significant TGF-beta response to BPM, P2 and P0 was observed at lower levels than the IFN-gamma response and at onset of recovery, consistent with a disease down-regulating role of TGF-beta. IL-4 mRNA-expressing cells were found at levels similar to TGF-beta mRNA-expressing cells, and with the latest peak of the three cytokines examined. This result suggests that IL-4 may also suppress IFN-gamma expression at late recovery phase of EAN.

Animals↗

PubMed1994

Th1-like cell responses to peripheral nerve myelin components over the course of experimental allergic neuritis in Lewis rats.

Experimental allergic neuritis (EAN) is a T cell-mediated animal model of Guillain-Barré syndrome characterized by inflammation and demyelination of peripheral nerves. EAN can be induced by immunization of rats with bovine peripheral nerve myelin (BPM) or the myelin proteins P2 or P0, but the extent of T cell responses over the course of EAN is incompletely defined. We studied the T cell responses to these proteins and the glycolipid GM1 by enumerating T helper type 1 (Th1)-like cells secreting interferon-gamma (IFN-gamma) after short-term culture of mononuclear cells (MNC) in presence of antigen. Already 7 days post immunization (p.i.) with BPM and before onset of clinical EAN, lymph nodes contained elevated levels of P2 responsive T cells. At the height of EAN on day 14 p.i. and during recovery, T cell levels responding to BPM, P0 and GM1 were also elevated. The same temporal profiles and specificities were registered for antigen reactive spleen MNC. The results implicate that Th1-like cells with multiple specificities including the glycolipid GM1 occur at increased levels in lymphoid organs in EAN rats, and that IFN-gamma may be an important effector molecule in the induction of nerve damage.

Animals↗

PubMed1994

Effect of mutations in genes affecting homologous recombination on restriction enzyme-mediated and illegitimate recombination in Saccharomyces cerevisiae.

Restriction enzyme-mediated events (REM events; integration of transforming DNA catalyzed by in vivo action of a restriction enzyme) and illegitimate recombination events (IR events; integration of transforming DNA that shares no homology with the host genomic sequences) have been previously characterized in Saccharomyces cerevisiae. This study determines the effect of mutations in genes that are involved in homologous recombination and/or in the repair of double-stranded DNA breaks on these recombination events. Surprisingly, REM events are completely independent of the double-strand-break repair functions encoded by the RAD51, RAD52, and RAD57 genes but require the RAD50 gene product. IR events are under different genetic control than homologous integration events. In the rad50 mutant, homologous integration occurred at wild-type frequency, whereas the frequency of IR events was 20- to 100-fold reduced. Conversely, the rad52 mutant was grossly deficient in homologous integration (at least 1,000-fold reduced) but showed only a 2- to 8-fold reduction in IR frequency.

Base Sequence↗

PubMed1994

Age estimation by Chinese permanent teeth with image analysis.

A total of 567 human teeth except third molars were studied to estimate age, using a combined method of multiple regression analysis of data from a scoring system, direct measurements with image analyser, and logarithmic transformation. As a result, the standard errors of estimate were 4.8-5.4 years in the working sample, and 2.9-5.4 years in the control sample respectively, by using a single tooth. By testing the formulae on forensic autopsy cases in Guang Dong and Guang Xi, (People's Republic of China), it is demonstrated that the standard error of estimate is 3.7 and 2.6 years respectively for any single tooth (incisor, canine, premolar or molar) except the third molar. Age determination from multiple teeth of the same individual has also been studied. As a result, according to the different age grouping, the standard errors of estimate ranged from 0.8 to 2.6 years (2 teeth from the same individual) and 0.6 to 2.3 years (3 teeth from the same individual). It is concluded that the method presented here is helpful in improving the accuracy of age determination from teeth.

Adolescent↗

PubMed1994

Human pituitary adenomas show no loss of heterozygosity at the retinoblastoma gene locus.

The retinoblastoma tumor suppressor gene (RB1) is inactivated in hereditary and sporadic forms of retinoblastoma as well as in a number of other sporadic tumors. The majority of human pituitary tumors have been shown to be monoclonal neoplasms, suggesting that 1 or more somatic mutations are involved in the clonal expansion of a single progenitor cell. Recently, a high percentage of transgenic mice containing a disrupted RB1 allele have been shown to develop pituitary tumors. To investigate whether RB1 inactivation contributes to the development of human pituitary adenomas, we searched for loss of heterozygosity (LOH) within the RB1 gene locus in a variety of human pituitary adenomas. We screened 34 adenomas for LOH using a polymerase chain reaction (PCR)-based microsatellite polymorphic marker at the RB1 gene locus. In addition, a variable number of tandem repeat markers from within the RB1 gene was also used to search for LOH in 14 tumors. We found no LOH or microsatellite instability at the RB1 locus in any of the informative cases (30 of 34). Additionally, we showed that 4 representative adenomas from female patients are monoclonal in origin using a PCR-based clonality analysis assay. We conclude that the RB1 gene shows no LOH in a variety of human pituitary adenomas and that PCR-based microsatellite markers can serve as a useful tool for LOH analysis in human pituitary tumors.

Adenoma↗

PubMed1994

Deletion of 3 basepairs resulting in the loss of lysine-121 in the insulin receptor alpha-subunit in a patient with leprechaunism: binding, phosphorylation, and biological activity.

We have identified a novel mutation of the human insulin receptor gene in a previously unreported patient with leprechaunism, leprechaun Rochester. This mutation consists of deletion of three nucleotides (GAA) in exon 2 and results in loss of the lysine-121 in the putative ligand-binding domain of the alpha-subunit. To analyze this mutation, we prepared a corresponding mutant insulin receptor by site-directed mutagenesis and expressed the receptor in Chinese hamster ovary cells. Although the mutant receptor displayed normal insulin binding, abnormalities were found in autophosphorylation and in phosphorylation of endogenous and exogenous protein substrates. These abnormalities consisted of increased basal kinase activity, but blunted insulin-stimulated responsiveness. Importantly, cells that expressed the mutant receptor showed markedly decreased insulin- and serum-stimulated DNA synthesis compared to untransfected control cells and cells transfected with the wild-type insulin receptor. These findings suggest that deletion of lysine-121 in conjunction with a presumed, but thus far unidentified, second mutant allele contributed significantly to the lethal insulin-resistant state in this patient with leprechaunism.

Alleles↗

PubMed1994

Genetic aberrations in human brain tumors.

Over the last decade, much has been learned about the genetic changes that occur in human neoplasia and how they contribute to the neoplastic state. Oncogenes and tumor suppressor genes have been identified, and many powerful molecular genetic techniques have emerged. Brain tumors have been intensively studied as part of this process. Specific and recurring genetic alterations have been identified and are associated with specific tumor types. In astrocytomas, for example, losses of genetic material on chromosomes 10 and 17 and amplification of the epidermal growth factor receptor gene seem important in pathogenesis, with the loss of chromosome 10 and the amplification of epidermal growth factor receptor being strongly associated with glioblastoma multiforme. Meningiomas, on the other hand, have usually lost part or all of chromosome 22. Brain tumors also express growth factors and growth factor receptors that may be important in promoting tumor growth and angiogenesis. These include epidermal growth factor, transforming growth factor-alpha, platelet-derived growth factor, the fibroblast growth factors, and vascular endothelial growth factor. In this article, we review the genetic aberrations that occur in the major types of brain tumors, including glial tumors, meningiomas, acoustic neuromas, medulloblastomas, primitive neuroectodermal tumors, and pituitary tumors. Wherever possible, clinical correlations have been made concerning the prognostic and therapeutic implications of specific aberrations. We also provide some background about the cytogenetic and molecular genetic techniques that have contributed to the description and understanding of these alterations and speculate as to some clinical and basic science issues that might be explored in the future.

Brain↗

PubMed1994

Characteristics of acupuncture meridians and acupoints in animals.

In recent years, an increasing number of studies has been conducted on the biophysical characteristics of the meridians and acupoints in humans and animals. The authors aim to further illustrate the objective existence and superficial locations of the meridians in various species of animals. Twelve sheep, ten goats, thirteen pigs, eleven cats, eight rabbits and seven donkeys were used to measure low impedance lines (LILs) and high percussion sound lines (HPSLs) on the skin surface of the animals, along the vertical planes of the dorsal line, using electrical impulses and high percussion sound. The results of these studies are given.

Acupuncture Points↗

PubMed1994

Human monoclonal antibody-drug conjugates in the experimental treatment of malignant gliomas--studies in vitro and in vivo.

The chemotherapeutic agents doxorubicin (DXR) and 4'-epi-doxorubicin were separately conjugated to the human monoclonal antibody CLNIgG, which binds strongly to human malignant glioma cells. The antibody-drug conjugates were more potent than the free drugs in killing human glioma cells in vitro and in vivo (subcutaneous glioma model). A biodistribution study using [14-14C]DXR-CLNIgG conjugate indicated that immunoconjugates delivered at least five times more DXR to glioma tissues than free DXR alone in nude mice without increasing the concentration in other tissues. In a nude rat intracerebral glioma model, intracarotid hyperosmolar perfusion to achieve blood-brain barrier (BBB) opening caused a 640% increase in the DXR-CLNIgG concentration in intracerebral tumor tissue. Human monoclonal antibody-drug conjugates in combination with BBB opening is a potential new approach to the treatment of malignant gliomas.

Animals↗

PubMed1994

Influence of K+ channel openers on interferon-gamma dependent immune response in experimental allergic neuritis (EAN).

We examined the influence of the K+ channel opening drugs BRL 38227, pinacidil and diazoxide on cellular immune response and clinical course of experimental allergic neuritis (EAN) actively induced in Lewis rats by bovine peripheral myelin (BPM). T cell functions of EAN lymph node cells were assessed by measurement of proliferation and by counting of interferon-gamma secreting cells (IFN-gamma sc) in response to the specific antigen BPM and the T cell mitogen phytohemagglutinin (PHA). BRL 38227 and diazoxide at concentrations of 10(-5)M-10(-6)M and pinacidil at concentrations of 10(-5)M-10(-7)M enhanced the proliferative response to both BPM and PHA. The number of IFN-gamma sc was suppressed by the K+ channel openers in the same concentration range. There was a tendency of stronger suppression of cultures with high numbers of BPM-reactive IFN-gamma sc than of cultures with low numbers of BPM-reactive IFN-gamma sc. The applied K+ channel openers are primarily acting on ATP-sensitive K+ channels, which have not been found in T cells so far. The drugs may, therefore, exert non-selective effects on conventional voltage- and/or Ca(++)-dependent channels of T cells. A first trial with in vivo administration of 2.5 mg/kg x day of the drugs resulted in more severe neurological deficits in the early phase of EAN with BRL 38227, whereas pinacidil and diazoxide had no significant effects.

Animals↗