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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 775 records · Page 43Linked to original sources
PubMed1992

Construction and characterization of a region-specific microdissection library from human chromosome 2q35-q37.

A region-specific genomic library for human chromosome 2q35-q37 has been constructed using the microdissection and polymerase chain reaction-mediated linker-adaptor microcloning method. Twenty fragments from the chromosome region 2q35-q37 were dissected and a library consisting of 20,000 recombinant microclones was obtained. The insert size ranged between 50 and 800 bp, with a mean of approximately 270 bp. About 50-60% of the microclones contained unique sequences. The microdissection library has been demonstrated to derive from the dissected region 2q35-q37 by chromosome painting using the fluorescence in situ hybridization (FISH) technique. Southern blot analysis of the unique sequence microclones from the library showed that 54% (26/48) of the clones are of human origin and chromosome 2 specific. Four of these microclones have been further mapped to the 2q37 region by using a cell hybrid containing only 2q37. The unique sequence microclones have also been characterized for their insert size and the hybridizing genomic fragments cleaved with HindIII. As shown previously, these microclones will be useful in isolating corresponding yeast artificial chromosome (YAC) clones with large inserts for high-resolution physical mapping and also in screening cDNA libraries to isolate expressed gene sequences as candidate genes to facilitate search for the crucial genes underlying genetic diseases and specific forms of cancer assigned to the region.

Blotting, Southern↗
PubMed1992

Magnetic resonance imaging, microangiography, and histology in a rat model of primary liver cancer.

RATIONALE AND OBJECTIVES: N-nitrosodiethylamine is able to induce various benign and malignant liver lesions in rats with a high success rate and a low mortality rate. It provides a more appropriate model that better simulates the various lesions occurring in patients than the usual model of tumor implantations. METHODS: Hepatic carcinogenesis was induced in 58 Wistar rats using oral N-nitrosodiethylamine. The rats subsequently were studied by liver magnetic resonance imaging (MRI), postmortem microangiography, and histologic examination. RESULTS: Hepatic tumors developed in 57 rats. A wide variety of the tumors in the degree of vascularization, the type of vessels, the areas of intratumoral secretion and necrosis, and the tumor cell differentiation resulted from the tumor model. The authors were able to assess the contribution of the vascular, extravascular, and cellular components in the final pattern of contrast enhancement in MRI. CONCLUSIONS: The N-nitrosoethylamine model for hepatic tumor induction is simple, and provides a more representative range of tumors for experimental evaluation.

Animals↗
PubMed1992

A homologue of the Escherichia coli DsbA protein involved in disulphide bond formation is required for enterotoxin biogenesis in Vibrio cholerae.

A strain of Vibrio cholerae, which had been engineered to express high levels of the non-toxic B subunit (EtxB) of Escherichia coli heat-labile enterotoxin, was subjected to transposon (TnphoA) mutagenesis. Two chromosomal TnphoA insertion mutations of the strain were isolated that showed a severe defect in the amount of EtxB produced. The loci disrupted by TnphoA in the two mutant derivatives were cloned and sequenced, and this revealed that the transposon had inserted at different sites in the same gene. The open reading frame of the gene predicts a 200-amino-acid exported protein, with a Cys-X-X-Cys motif characteristic of thioredoxin, protein disulphide isomerase, and DsbA (a periplasmic protein required for disulphide bond formation in E. coli). The V. cholerae protein exhibited 40% identity with the DsbA protein of E. coli, including 90% identity in the region of the active-site motif. Introduction of a plasmid encoding E. coli DsbA into the V. cholerae TnphoA derivatives was found to restore enterotoxin formation, whilst expression of Etx or EtxB in a dsbA mutant of E. coli confirmed that DsbA is required for enterotoxin formation in E. coli. These results suggest that, since each EtxB subunit contains a single intramolecular disulphide bond, a transient intermolecular interaction with DsbA occurs during toxin subunit folding which catalyses formation of the disulphide in vivo.

Amino Acid Sequence↗
PubMed1992

Cloning and characterization of the eae gene of enterohaemorrhagic Escherichia coli O157:H7.

The eae (Escherichia coli attaching and effacing) gene from enteropathogenic Escherichia coli (EPEC) was previously shown to be essential for production of the 'attaching and effacing' histopathology characteristic of EPEC infections (Jerse et al., 1990). We have now cloned the eae gene from enterohaemorrhagic E. coli (EHEC) which, in addition to producing Shiga-like cytotoxins, also produces the attaching and effacing effect. The sequence homology between the EPEC and EHEC sequences was 86% and 83% at the nucleotide and amino acid levels, respectively. The predicted amino acid sequence of the EHEC eae gene shared 31% identity and 51% similarity with invasin of Yersinia pseudotuberculosis. Alignment of the EPEC and EHEC Eae proteins and the Y. pseudotuberculosis and Y. enterocolitica invasins shows striking regions of identity with the greatest divergence at the C-terminal end, the putative receptor-binding portion of invasin.

Adhesins, Bacterial↗
PubMed1992

Early Caulobacter crescentus genes fliL and fliM are required for flagellar gene expression and normal cell division.

The biogenesis of the Caulobacter crescentus polar flagellum requires the expression of more than 48 genes, which are organized in a regulatory hierarchy. The flbO locus is near the top of the hierarchy, and consequently strains with mutations in this locus are nonmotile and lack the flagellar basal body complex. In addition to the motility phenotype, mutations in this locus also cause abnormal cell division. Complementing clones restore both motility and normal cell division. Sequence analysis of a complementing subclone revealed that this locus encodes at least two proteins that are homologs of the Salmonella typhimurium and Escherichia coli flagellar proteins FliL and FliM. FliM is thought to be a switch protein and to interface with the flagellum motor. The C. crescentus fliL and fliM genes form an operon that is expressed early in the cell cycle. Tn5 insertions in the fliM gene prevent the transcription of class II and class III flagellar genes, which are lower in the regulatory hierarchy. The start site of the fliLM operon lies 166 bp from the divergently transcribed flaCBD operon that encodes several basal body genes. Sequence comparison of the fliL transcription start site with those of other class I genes, flaS and flaO, revealed a highly conserved 29-bp sequence in a potential promoter region that differs from sigma 70, sigma 54, sigma 32, and sigma 28 promoter sequences, suggesting that at least three class I genes share a unique 5' regulatory region.

Amino Acid Sequence↗
PubMed1992

Role of antibiotic production by Erwinia herbicola Eh252 in biological control of Erwinia amylovora.

Erwinia herbicola Eh252 is a nonpathogenic epiphytic bacterium that reduces fire blight incidence when sprayed onto apple blossoms before inoculation with Erwinia amylovora, the causal agent of fire blight. Eh252 was found to produce on minimal medium an antibiotic that inhibited the growth of E. amylovora. This antibiotic was inactivated by histidine but not by Fe(II), was sensitive to proteolytic enzymes, and showed a narrow host range of activity. To determine the role of this antibiotic in the control of fire blight, two prototrophic Tn5-induced mutants, 10:12 and 17:12, that had lost their ability to inhibit E. amylovora on plates (Ant- mutants) were compared with the wild-type strain for their ability to suppress fire blight in immature pear fruits. The two mutants had single Tn5 insertions in the chromosome; although they grew in immature pear fruits at a rate similar to that of the wild-type strain, neither of these mutants suppressed fire blight as well as Eh252 did. The Tn5-containing fragment isolated from 10:12 was used to mutagenize Eh252 by marker exchange. Derivatives that acquired the Tn5-containing fragment by homologous recombination lost the ability to inhibit E. amylovora on minimal medium. Furthermore, the three Ant- derivatives tested were also affected in their ability to inhibit E. amylovora in immature pear fruits. The results obtained suggest that antibiotic production is a determinant of the biological control of E. amylovora by Eh252, but that another mechanism(s) is involved.

Anti-Bacterial Agents↗
PubMed1992

Intestinal uptake and lymphatic absorption of beta-carotene in ferrets: a model for human beta-carotene metabolism.

To determine the appropriateness of the ferret as a model for human beta-carotene (beta-C) metabolism, we have perfused both 15,15'-beta-[14C]C and unlabeled beta-C through the upper 30-cm portion of the small intestine of ferrets in vivo. The effluents of a mesenteric lymph duct cannulation and a common bile duct cannulation, as well as portal vein blood periodically sampled via an indwelling catheter, were collected. Ten percent (9.5 +/- 0.06%) of the total administered beta-C was taken up by the intestine after a 4-h perfusion. Of the radioactivity taken up, 68.6 +/- 6.5% remained in the intestinal mucosa, 3.2 +/- 0.2% was recovered in the lymph, and 28.2 +/- 6.5% (calculated) was absorbed via the portal system. The total uptake/absorption of beta-C was 12.9 +/- 6.8 nmol.h-1.30 cm intestine-1. Large amounts of unchanged beta-C and relatively small amounts of both beta-apo-12'-carotenal and beta-apo-10'-carotenal were isolated in the intestinal mucosa after a 4-h perfusion with beta-C. Considerable amounts of metabolites more polar than retinol were formed and comprised 35% of the total radioactivity recovered in the intestinal mucosa. Polar metabolites were absorbed mostly into the portal venous system, whereas retinol and retinyl esters were absorbed mainly into the mesenteric lymph. Of the total absorbed radioactivity in lymph, 10 +/- 1.0% appeared as unchanged beta-C, with peak absorption occurring at 3 h after beginning the perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1992

The age of alcohol onset and alcohol, cigarette, and marijuana use patterns: an analysis of drug use progression of young adults in New York State.

The authors extend the gateway theory by examining the relationship between the onset age of alcohol and the progression of drug use (alcohol, cigarettes, and marijuana) among 16 to 24 year old young adults residing in New York State. Logit analysis is employed to estimate the impact of the early onset of alcohol use on the subsequent use of other drugs. The findings suggest that alcohol use increases the chance of using cigarettes and marijuana, and alcohol-cigarette use significantly increases the likelihood of using marijuana. The early onset of alcohol use affects the current use of alcohol and other drugs; the impact is the strongest when the onset is initiated in a posited critical age period between 13 and 16.

Adolescent↗
PubMed1992

DWI/DWAI offenders and recidivism by gender in the eighties: a changing trend?

The study is based on a systematic random sample from the New York State's Driver License File, which contains 15,032 drivers who were convicted of DWI/DWAI at least once in the period of 1978 to 1988. The analysis reveals (1) the proportion of male offenders 20 and younger continued to decrease through the 1980s, while the proportion of female offenders 21 and older increased; and (2) the female DWI/DWAI recidivism rate began to parallel the male recidivism rate after the mid-1980s. A number of factors may be attributed to the changing DWI/DWAI structure, such as the impact of the 21 alcohol purchase age law, the change of women's roles and lifestyles, and the changing attitudes of the public and the police toward female drinking-driving.

Adult↗
PubMed1992

[Mechanism of shen qian gujing granule in the treatment of menorrhagia].

Shen Qian Gujing Granule, a Chinese herbal preparation has shown its efficacy of 87.7% in treating menorrhagia. PGE2, PGE2 alpha, TXB2 and 6-Keto-PGF1 alpha levels were measured in the endometrium and menstrual blood of both normal menstrual women and patient with menorrhagia before and after the treatment. Local TXB2 values of endometrial and menstrual blood were significantly higher in menorrhagia patients than that in normal subjects (P < 0.05). And the local PGE2 values were higher in patients accompanied with Qi Deficiency (P < 0.05) and lower in patients without Qi Deficiency (P < 0.05). After the treatment, the local TXB2, PGE2 levels normalized. It suggests that Shen Qian Gujing Granule had a biphasic regulation on local PG values which yields good results for menorrhagia. Some mechanism were discussed.

Adult↗
PubMed1992

Identification of an 85-100 kDa glycoprotein as a cell surface marker for an advanced stage of urothelial differentiation: association with the inter-plaque ('hinge') area.

Although bladder cancers account for almost 5% of all human cancer deaths, little is known about the biochemistry of urothelial differentiation. We have recently identified three major protein subunits ('uroplakins') of asymmetric unit membranes (AUM), which form rigid-looking plaques covering up to 70% of the apical surface of urothelial superficial (umbrella) cells. The ordinary-looking plasma membranes that interconnect these plaques are believed to be functionally specialized, serving as flexible but durable 'hinges'. Whether these hinge membranes are biochemically unique is unknown. Using a new monoclonal antibody (AE32) we have identified an 85-100 kDa glycoprotein (UGP85) which appears to be urothelium-specific. In both normal urothelium and cultured urothelial colonies this cell surface protein is associated mainly with superficial cells, suggesting that its expression is differentiation dependent. Results from in vitro translation experiments indicated that this glycoprotein contains a core polypeptide of about 55 kDa. Using immunogold localization techniques, we showed that in cultured urothelial colonies--which are known to lack mature AUM plaques--UGP85 is distributed relatively uniformly on the apical surface of some differentiated cells. However, in superficial cells of normal urothelium UGP85 is mainly associated with the hinge areas. These results raise the possibility that UGP85 is a plasma membrane component which can be excluded, to varying extents, from the plaque region as 12 nm protein particles are assembled into a tightly packed paracrystalline AUM structure. The identification of UGP85 provides the first evidence that the hinge areas interconnecting the urothelial plaques are biochemically distinguishable from the plasma membranes of the relatively undifferentiated urothelial cells of the lower cell layers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Effect of electroacupuncture point on the value of ventricular fibrillation threshold in rats].

The Neiguan and Lingdao were stimulated by electroacupuncture in anesthetized Wistar rats. We observed that the value of ventricular fibrillation threshold (VFT) was increased significantly in 30 min of electro-acupuncturing (P less than 0.01) and in 15 min of stopping the acupuncturing (P less than 0.05). Although the value of VFT was increased until 30 min of stopping acupuncture, it was not significantly different compared with its basic value. The control group were dealt with the same way as the experimental group except electroacupuncture. The value of VFT measured in control group were not significantly different compared with its basic value.

Acupuncture Points↗
PubMed1992

Regulation of production of activin A in human marrow stromal cells and monocytes.

In studies of the regulation of hematopoiesis, increasing attention has focused on the role of bone marrow stromal cells as rich sources of various cytokines. Present studies indicate that marrow stromal cells and monocytes produce activin A, implicating this new cytokine in the paracrine control of hematopoiesis. Activin A, which was initially recognized as a beta A beta A dimeric gonadal protein, was found to potentiate the proliferation and differentiation of erythroid progenitors; both purified erythroid colony-forming units (CFU-E) and K562 cells possess high affinity receptors specific for activin A. Present studies using Western and Northern blots demonstrate the presence of beta A subunits of activin A in the conditioned medium of monocytes and stromal cells and its RNA transcripts in these cells. The presence of functional and homodimeric beta A beta A activin molecule was confirmed through bioassay with or without a blocking antiserum against activin A or an activin binding protein, follistatin; its presence is further supported by a specific enzyme-linked immunosorbent assay (ELISA) in which a monoclonal antibody reacted only with the beta A beta A dimeric form of this molecule. In other experiments, the production of activin A was found to be regulated by various cytokines and regulators. The production of activin A in monocytes was stimulated more than ninefold by treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF). Activin A expression was also stimulated, albeit less potently, by bacterial lipopolysaccharide (LPS) and gamma-interferon. On the other hand, the expression of activin A in marrow stromal cells was upregulated by incubation with tumor necrosis factor-alpha (TNF-alpha), LPS, and interleukin 1 alpha (IL-1 alpha). Therefore, we propose that the local production of activin A in the microenvironment within bone marrow may fine tune the regulation of steady-state hematopoiesis. In addition, this factor may normally be produced at minimal levels, but under certain situations may be further induced to provide important biological functions.

Activins↗
PubMed1992

Anterior shoulder dislocations.

The glenohumeral joint of the shoulder is the most commonly dislocated joint in the body. When dislocation occurs, it is usually anterior. The primary care physician usually sees the patient after reduction has been performed. Thus, treatment is directed at recovery of function and preventing recurrences. The prognosis and likelihood of recurrence in a first-time anterior dislocation depends on the mechanism of injury, treatment, rehabilitation, sex, age, and complications. Non-operative treatment after reduction usually involves immobilization and rehabilitation. Studies to date seem to indicate that age and activity level are more important factors for recurrence than length of immobilization. Traditionally, if there are recurrences after conservative treatment, then surgery is contemplated.

Adult↗
PubMed1992

Extended parietal cell vagotomy in the treatment of perforation, hemorrhage and stenosis due to duodenal ulcer.

Ninety-five patients with perforation, hemorrhage or stenosis due to duodenal ulcer were treated by extended parietal cell vagotomy. Postoperative follow-up ranged from 3.5 to 10 years (mean 6 years) in 88 patients (92%) with acute perforation (60), hemorrhage (8) and stenosis (20). There was no operative mortality. Ulcer recurrence was 2.3%. Only one patient (5%) had restenosis and required reoperation. There was no recurrent hemorrhage and there were few long-term complications. According to the Visick classification, 67 patients (76%) belonged to grade I, 13 (14.7%) grade II, 4 (4.5%) grade III, and 4 (4.5%) grade IV. Extended parietal cell vagotomy proved to be safe with excellent results, low ulcer recurrence and few complications. Moreover, recurrent ulcers healed rapidly following medical therapy. The authors believe that extended parietal cell vagotomy should be the treatment of choice for acute perforation, hemorrhage or stenosis due to duodenal ulcer.

Adolescent↗
PubMed1992

Isolation, characterization, and regional mapping of microclones from a human chromosome 21 microdissection library.

Thirty-four unique-sequence microclones were isolated from a previously described microdissection library of human chromosome 21 and were regionally mapped using a cell hybrid mapping panel which consists of six cell hybrids and divides chromosome 21 into eight regions. The mapping results showed that the microclones were unevenly distributed along chromosome 21, with the majority of microclones located in the distal half portion of the long arm, between 21q21.3 and 21qter. The number of unique-sequence clones began to decrease significantly from 21q21.2 to centromere and extending to the short arm. This finding is consistent with those reported in other chromosome 21 libraries. Thus, it may be inferred that the proximal portion of the long arm of chromosome 21 contains higher proportions of repetitive sequences, rather than unique sequences or genes. The microclones were also characterized for insert size and were used to identify the corresponding genomic fragments generated by HindIII. In addition, we demonstrated that the microclones with short inserts can be efficiently used to identify YAC (yeast artificial chromosome) clones with large inserts, for increased genomic coverage for high-resolution physical mapping. We also used 200 unique-sequence microclones to screen a human liver cDNA library and identified two cDNA clones which were regionally assigned to the 21q21.3-q22.1 region. Thus, generation of unique-sequence microclones from chromosome 21 appears to be useful to isolate and regionally map many cDNA clones, among which will be candidate genes for important diseases on chromosome 21, including Down syndrome, Alzheimer disease, amyotrophic lateral sclerosis, and one form of epilepsy.

Base Sequence↗