Search PubMed⌕ Search

Biomedical subjects

J Yao

Publications and source records attributed to J Yao.

At least 271 records · Page 15Linked to original sources
PubMed1992

Decreased collagen mRNA and regression of cardiac fibrosis in the ventricular myocardium of the tight skin mouse following thyroid hormone treatment.

OBJECTIVE: The aim was to study the effect of thyroid hormone on collagen gene expression in the myocardium of the tight skin mouse (TSK), a genetic model of myocardial fibrosis. METHODS: Heterozygous male (TSK/+) (n = 20) and normal (+/+) homozygous mice (n = 20), 1.5-2 months old of the C57 BL/6 strain were studied. Ventricular hypertrophy following thyroid hormone treatment (L-thyroxine, 10 micrograms.100 g-1 body weight daily intraperitoneally) was examined by measurement of the heart weight/body weight ratios and histological changes. Expression of fibrillar collagen types I and III in the ventricular myocardium was examined by measurement of the abundance of their respective mRNAs. Collagen synthesis was examined by measurement of hydroxyproline. Deposition of collagen types was evaluated by immunofluorescence staining. Expression of non-collagenous proteins, sarcomeric and cytoskeletal actin, was measured at the mRNA level. RESULTS: After 12 days of treatment ventricular hypertrophy was induced in the heart of the TSK mice. The results of northern hybridisation analyses showed that in the hearts of TSK mice 24 h after thyroxine treatment the abundance of mRNA for pro alpha 2 (I) collagen was decreased by 32% (p less than 0.05), pro alpha 1 (III) collagen by 47% (p less than 0.002), cytoskeletal actin by 50% (p less than 0.005), and sarcomeric actin mRNA by 34% (p less than 0.01) compared to the untreated TSK mice. The abundance of mRNA for pro alpha 2 (I) and pro alpha 1 (III) collagens in the thyroxine treated TSK mice were nearly comparable to that in normal homozygous mice. In TSK mice which were treated for 12 d, collagen content of the ventricular myocardium, as determined by hydroxyproline measurements, was decreased by 22.5% (p less than 0.01) compared to that in the heart of normal homozygous mice. CONCLUSIONS: Effects of thyroid hormone on ventricular gene expression in TSK mice result in a diminished collagen mRNA and collagen content and the disappearance of cardiac fibrosis. Thyroid hormone may selectively prevent the induction of cardiac fibrosis and play an important role in regression of cardiac fibrosis via endocrine pathways.

Animals↗
PubMed1992

Decreased collagen gene expression and absence of fibrosis in thyroid hormone-induced myocardial hypertrophy. Response of cardiac fibroblasts to thyroid hormone in vitro.

The regulatory effects of thyroid hormone on biosynthesis of myocardial proteins that originate from cardiac myocytes are well established. Little is known, however, of regulatory effects of thyroid hormone on interstitial proteins. In this study we examined the effects of thyroid hormone on collagen gene expression in thyroid hormone-induced myocardial hypertrophy and the response of cardiac fibroblasts to thyroid hormone in culture. Adult male Sprague-Dawley rats were treated intraperitoneally with L-thyroxin (10 micrograms/100 g body wt) for 2 hours or 1, 2, 3, 6, 12, or 14 days. Northern blot analysis of RNA from total ventricular tissue showed that after 2 hours of treatment, the abundance of mRNA for pro alpha 2(I) collagen decreased by 53% (p less than 0.05) and reached the lowest level (60% decrease, p less than 0.02) at day 1, remained diminished at day 3, and then gradually returned toward normal levels. After transient transfection of chimeric DNA containing collagen type I promoter-chloramphenicol acetyl transferase (CAT) gene into the thyroxin-treated cardiac fibroblasts, the level of CAT activity decreased significantly. Treatment of cardiac fibroblasts in culture (10 nM L-thyroxin) resulted in a 33% (p less than 0.005) decrease in the abundance of mRNA for pro alpha 2(I) collagen. The stability of the mRNA for pro alpha 2(I) collagen in cardiac fibroblasts, as measured by mRNA half-life, was slightly (16.6%) decreased by thyroid-hormone treatment. Collagen synthesis as shown by immunofluorescent staining of intracellular collagen in cultured fibroblasts and in frozen sections of myocardium was also diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetyltransferases↗
PubMed1992

Lectin staining of cultured CNS microglia.

Carbohydrate binding proteins, known as lectins, bind to specific sugar groups on most membranes. We used fluorescent and light microscopy to study the interaction of various lectins with the membranes of microglia cultured from neonatal rat or fetal mouse cerebral cortices. Microglia stained intensely with GS-1, RCA, WGA, and ConA and slightly with DBA, UEA, BPA, and SBA. No staining was seen with GS-2, MPA, or PNA. Staining was specific for microglia in the mixed glial cultures and was dose dependent. In addition, microglial lectin binding could be reduced or blocked by competitive inhibition using specific sugars. Treatment of the microglia with agents such as dimethylsulfoxide (DMSO), interleukin-1 (IL-1), interferon (IFN), or lipopolysaccharide (LPS) did not eliminate lectin staining, although the degree of staining was altered. Positive staining of the microglia was also associated with a functional change for at least one lectin, i.e., ConA. Superoxide anion production by microglia was increased in the presence of ConA. Overall, binding of the lectins GS-1, RCA, WGA, and ConA can be used as an identifying tool for microglia in glial cultures, but intensity of staining varies depending on their functional state.

Animals↗
PubMed1992

[Diagnosis and treatment of blunt renal injury].

157 renal injury cases (22.2%) of 708 blunt abdominal injury cases admitted at our hospital from January, 1981 to April, 1991 were evaluated. The results suggested that large dose IVP have certain limitations, while modern ultrasound findings have important practical value. We think that the patients with renal injury more than 3 degree must be operated immediately. Nephrectomy may be considered on injured kidney if the contralateral renal function is normal, in order to avoid late complications. In cases of using inosine, dopamine and large furosemide during operation, the time lag of indicamine presenting in urine is helpful for judging and protecting contralateral renal function.

Adolescent↗
PubMed1992

Racial misclassification of American Indians with AIDS in Los Angeles County.

American Indian/Alaska Natives (AI/ANs) appear to be underrepresented in AIDS surveillance statistics. We estimated the accuracy of racial classification and reporting completeness of AIDS among AI/ANs in Los Angeles County by surveying community-based organizations (CBOs) that provide services to persons with AIDS and then comparing the survey to AIDS surveillance data. The surveyed CBOs reviewed 6,500 records and found 60 Native American (the classification used by CBOs for AI/ANs) clients with AIDS compared with six AI/AN AIDS cases reported to the Los Angeles County AIDS surveillance registry. Racial classification was evaluated for 37 (62%) of the 60 Native American CBO clients. Only 11 (30%) of the 37 were verified as AI/ANs. The remaining 26 (70%) misunderstood the racial nomenclature and were reclassified by the CBOs as other races. Of 10 verified AI/AN clients for whom names were available, eight (80%) had been reported to the AIDS registry. However, seven (88%) of these eight were erroneously reported as other races. Racial misclassification accounts for much of the underrepresentation of AI/ANs in the Los Angeles County AIDS surveillance registry.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Cloning and expression of midecamycin 4"-acylase gene in spiramycin producing strains.

A recombinant plasmid p66B containing the midecamycin 4"-acylase gene was obtained by cloning this gene into plasmid vetor pIJ680 from the primary clone pCN6C5, presumably harboring the midecamycin biosynthetic gene. The expression of the midecamycin 4"-acylase gene (p66B) in spiramycin producing strains resulted mainly in the production of 4"-isovalerylspiramycin. Another positive clone pCN10F5 was discovered from the genomic library of S. mycarofacians 1748 by probing with p66B DNA BamHI-BamHI 2.3kb fragment. A BamHI-BamHI 8.0kb homologous region on pCN10F5 was determined by Southern hybridization and was subcloned into plasmids pWHM3 and pIJ680. Recombinant plasmids pWF5 and p6F5 with molecular size about 15.2kb and 13.3kb, respectively, were obtained. Transformation of spiramycin producing strains with these plasmids resulted in the production of two major components. Based on their physicochemical properties and spectral evidences, component I was identified as 4"-propionylspiramycin III, and component II as 4"-propionylspiramycin II. Southern hybridization confirmed that the BamHI-BamHI 8.0kb fragment was cloned in the spiramycin producing strain. Only pCN10F5 clone was identified from the genomic library of S. mycarofaciens 1748 when the 4"-isovaleryltransferase gene of carbomycin producing strain S. thermotolerans was used as a probe in colony hybridization. It suggests that there is a difference between the 4"-acyltransferase genes in the pCN6C5 and pCN10F5 clones.

Acyltransferases↗
PubMed1991

Abnormal production of interleukin-1 by microglia from trisomy 16 mice.

The production of interleukin-1 (IL-1) was examined in cultured CNS microglia obtained from trisomy 16 (Ts16) fetal mouse brain, a model system for studies relevant to Down syndrome (DS). When compared to microglia from their normal littermates, Ts16 microglia produced significantly higher levels of IL-1 activity both before and following stimulation with lipopolysaccharide (LPS). IL-1 release was stimulated by alpha/beta interferon (IFN) in the normal but not Ts16 microglial cultures. The overall level of IL-1 production in normal littermates, however, was still less than that seen in Ts16. Thus, microglia from Ts16 mice may function in an inappropriate manner and, if this abnormality occurs in vivo, may have wide ranging effects on a developing nervous system.

Animals↗
PubMed1991

Linker DNA bending induced by the core histones of chromatin.

We have previously reported that ionic conditions that stabilize the folding of long chromatin into 30-nm filaments cause linker DNA to bend, bringing the two nucleosomes of a dinucleosome into contact [Yao, J., Lowary, P. T., & Widom, J. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7603-7607]. Dinucleosomes are studied because they allow the unambiguous detection of linker DNA bending through measurement of their nucleosome-nucleosome distance. Because of the large resistance of DNA to bending, the observed compaction must be facilitated by the histones. We have now tested the role of histone H1 (and its variant, H5) in this process. We find that dinucleosomes from which the H1 and H5 have been removed are able to compact to the same extent as native dinucleosomes; the transition is shifted to higher salt concentrations. We conclude that histone H1 is not essential for compacting the chromatin filament. However, H1 contributes to the free energy of compaction, and so it may select a single, ordered, compact state (the 30-nm filament, in long chromatin) from a family of compact states which are possible in its absence.

Animals↗
PubMed1991

CSF chromogranin A-like immunoreactivity in schizophrenia. Assessment of clinical and biochemical relationships.

Chromogranin A (CgA) is co-released with catecholamines and peptides and has a wide distribution in the brain. Chromogranin A provides a measure of tonic arousal. CSF CgA-like immunoreactivity (CgA-LI) was studied in 42 drug-free male schizophrenic patients. 33 of these patients were first studied during chronic haloperidol maintenance treatment. Withdrawal from haloperidol maintenance treatment was associated with a significant increase in CSF CgA-LI, particularly in the patients who did not relapse. Contrary to expectation CSF CgA-LI was higher in drug-free patients who slept longer the night before the lumbar puncture. Significant relationships were observed between CSF CgA-LI and CSF homovanillic acid, acetylcholinesterase, neuropeptide Y-LI and 5-hydroxy-indole acetic acid, but not with CSF norepinephrine or 3-methoxy-4-hydroxyphenylglycol. Ventricular brain ratios correlated negatively with CSF CgA-LI levels.

Adult↗
PubMed1991

The effect of xanthine/xanthine oxidase generated reactive oxygen species on synaptic transmission.

The effect of reactive oxygen species generated by the interaction of xanthine and xanthine oxidase on synaptic transmission was examined at the squid giant synapse and the lobster neuromuscular junction. Exposure of these synaptic regions to xanthine/xanthine oxidase produced a significant depression in evoked release, with no change in either resting membrane properties or in the action potential. Addition of catalase to the xanthine/xanthine oxidase-containing media partially blocked the synaptic depression, indicating that H2O2 contributes to the synaptic changes induced by exposure to xanthine/xanthine oxidase. H2O2 applied directly to the perfusing media also produced a decrease in synaptic efficacy. The results demonstrate that reactive oxygen species, in general, depress evoked synaptic transmission.

Action Potentials↗
PubMed1991

[Practical value of prostatography].

From September 1988 to September 1989 perineal puncture prostatography with 60% urografin was performed in 21 patients with the prostate enlargement. Prostatographic findings suggested that 15 patients had benign prostatic hyperplasia and 6 had prostatic cancer. The diagnosis had been histologically proved after prostatectomy in 19 cases. The procedure was easily and safely conducted at outpatient clinic without complications. We believe that prostatography is useful in differential diagnosis of prostatic diseases and in selecting operative methods.

Aged↗
PubMed1990

Norepinephrine in acute exacerbations of chronic schizophrenia. Negative symptoms revisited.

In recent years the dopamine hypothesis has failed to explain the complexities of schizophrenia. Because both negative symptoms and noradrenergic activity appear to increase with psychotic relapse, we studied negative symptoms, psychosis, cerebrospinal fluid norepinephrine, and cerebrospinal fluid monoamine metabolites in 32 male patients with a DSM-III diagnosis of schizophrenia while both receiving and not receiving long-term haloperidol treatment. Drug-free cerebrospinal fluid norepinephrine and 3-methoxy-4-hydroxyphenylglycol levels correlated significantly with the severity of negative symptoms and psychosis ratings. When the patients were divided into those who did and did not relapse while not receiving the drug, significant positive correlations between negative symptoms and cerebrospinal fluid norepinephrine and 3-methoxy-4-hydroxyphenylglycol were observed only in the patients who relapsed. Non significant but negative correlations were observed between the same variables in the nonrelapsers. Thus, increased norepinephrine activity in drug-free patients is associated with intensification of schizophrenic symptoms without necessarily causing the symptoms.

Acute Disease↗
PubMed1990

Chemotaxis by a CNS macrophage, the microglia.

Microglia demonstrate many characteristics similar to those seen in monocytes and tissue-specific macrophages, including phagocytosis, production of oxygen radicals, and growth factors and expression of MHC antigens. We have examined the ability of microglia, cultured from the cerebral cortices of neonatal rats, to demonstrate another important functional characteristic of monocytic-derived cells, that is, chemotaxis. Our results show that cultured rat microglia demonstrate chemotaxis to complement dependent chemoattractants such as recombinant C5a, zymosan activated serum, and to rat serum as well as to transforming growth factor-beta, a chemoattractant produced by platelets. Microglia fail to migrate to bacterial dependent chemoattractants such as the N-formyl peptides. The failure to respond is not dependent on maturational state of the microglia. Treatment with DMSO or casein, agents known to induce morphological and functional changes in cultured microglia reminescent of a "resting" and an "activated" macrophage, respectively, do not alter the response to fMet-Leu-Phe. In addition, the chemotactic response to serum in DMSO or casein-treated cells is the same as the response seen in untreated day 10 cultured microglia or untreated age-matched controls. The ability of microglia to migrate in response to inflammatory mediators suggests that these cells can move to sites of injury, thereby enabling them to participate in an inflammatory response.

Animals↗
PubMed1990

Direct detection of linker DNA bending in defined-length oligomers of chromatin.

Linker DNA, which connects between nucleosomes in chromatin, is short and, therefore, may be essentially straight and inflexible. We have carried out hydrodynamic and electron microscopic studies of dinucleosomes--fragments of chromatin containing just two nucleosomes--to test the ability of linker DNA to bend. We find that ionic conditions that stabilize the folding of long chromatin cause linker DNA in dinucleosomes to bend, bringing the two nucleosomes into contact. The results uphold a key prediction of the solenoid model of chromosome folding and suggest a mechanism by which proteins that are separated along the DNA can interact by direct contact.

Animals↗
PubMed1990

Stem fracture incidence in Trapezoidal-28 stainless steel hip arthroplasty.

From 1970 to March 1978, 716 forged stainless steel Trapezoidal-28 (T-28) total hip arthroplasties were performed at the authors' institution with a follow-up period from one to 15 years (mean, 64 months). There were 13 (1.8%) stem fractures and one (0.1%) neck fracture. Average time to fracture was 95 months. All fractures occurred in stems implanted before 1976, using early femoral acrylic stem fixation techniques. Stem fracture was related to time of surgery, stem size, patient height, patient weight (for males), and patient age. Survivorship analysis predicted an overall ten-year fracture rate of 4%, and a ten-year rate of 5% for T-28 stems implanted before 1976. There have been no reported fractures in the 204 T-28 stainless steel prostheses implanted since 1976. The mean patient follow-up period for the T-28 stems implanted after 1975 was 52 months, and only 16 patients have been followed for nine years or more. Thus, a longer patient follow-up period is needed in the post-1975 group in order to determine the long-term fracture rate in this group. However, the major difference between this group and the early group is the use of an improved cementation technique, as well as the use of larger prostheses when possible. There was no material or manufacturing change until the introduction of the TR-28 prostheses in 1978.

Adolescent↗
PubMed1989

CSF norepinephrine in schizophrenia is elevated prior to relapse after haloperidol withdrawal.

Thirty-two male DSM-III diagnosed schizophrenic patients received a lumbar puncture (LP) during chronic haloperidol treatment that was followed by replacement with placebo for up to 6 weeks. Fourteen patients relapsed on placebo within 6 weeks. Patients received a second LP at the time of relapse or at the end of 6 weeks if they had not relapsed. Bunney-Hamburg Global Psychosis Ratings of the day and the hours of sleep of the night before the LP were obtained, as were the Brief Psychiatric Ratings Scale (BPRS) ratings during the week of the LPs. CSF norepinephrine (NE), 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5 HIAA) concentrations were measured with high-pressure liquid chromatography (HPLC). Patients who relapsed had significantly higher CSF NE levels on and off haloperidol than patients who did not relapse. CSF MHPG was higher in the relapsers in the drug-free condition only, but CSF HVA and 5-HIAA were not significantly different in either condition. In the drug-free relapsed patients, CSF NE correlated significantly with the psychosis ratings of the day and hours of sleep the night prior to the LP. Our data indicate that elevated CSF NE levels during neuroleptic treatment may predict behavioral decompensation after discontinuing the medication.

Adult↗
PubMed1988

Complete atrioventricular block, retrograde atrial activation and intra-atrial block.

A case of complete atrioventricular block, retrograde atrial activation, and intra-atrial block was reported. Inhomogeneous inhibition of the atrioventricular junction and the so-called summation of impulses may both act together to make retrograde conduction possible when third-degree atrioventricular block was present. In lead 2, P waves were dome-shaped, and in lead V1, P waves were biphasic; narrow and peaked P waves intermittently appeared, denoting third-degree intra-atrial block. The peaked P waves signified that the right atrium was activated while the left atrium was not depolarized.

Atrioventricular Node↗