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Biomedical subjects

F Gao

Publications and source records attributed to F Gao.

At least 235 records · Page 13Linked to original sources
PubMed1994

Radioautographic study of benidipine hydrochloride. Localization in the mesenteric artery of spontaneously hypertensive rat.

Microradioautographic study of [3H]-benidipine hydrochloride (KW-3049, CAS 91599-74-5) and nitrendipine (CAS 39562-70-4) localization was performed in the supramesenteric arteries of the spontaneously hypertensive rats (SHR) at 10 and 30 min after intravenous administration or in vitro incubation. The distribution of silver grains was observed by light and electron microscopy and the number of grains was counted in the tunicae intima, media and adventitia of the arteries. Areas of the correlated part of the artery were measured and the grain count per area was calculated. The grain count of [3H]-benidipine hydrochloride showed almost uniform distribution in the tunicae intima and media, which was compared at 10 and 30 min after the administration both in the in vivo and in the in vitro studies. The grain density of [3H]-nitrendipine to the tunicae intima and media increased time-dependently. Electron microscopic observation revealed that the fine distribution of [3H]-benidipine hydrochloride was mainly localized on the plasma membrane and on the cytoplasm of the cellular components of the mesenteric artery. The result suggested that the distribution of [3H]-benidipine hydrochloride was related to its pharmacologically active site, i.e. plasma membrane of the tunica intima and the smooth muscle cells of the tunica media.

Animals↗
PubMed1994

MR of fetal central nervous system abnormalities.

PURPOSE: To investigate whether MR can provide additional information on fetuses with central nervous system abnormalities as demonstrated by ultrasonography. METHODS: Fetal MR examinations were studied prospectively in 22 pregnant women whose fetuses showed evidence of anomalies on ultrasound performed in the High-Risk Obstetric Clinic. RESULTS: In 19 of 22 cases, postpartum confirmatory diagnoses were obtained by MR or CT examinations, autopsy, or surgery. In general, the image quality of MR is comparable with that of ultrasound. However, in six of 22 cases (27%), MR provided additional information that altered the ultrasound diagnosis; these included cases of infarction, diastematomyelia, normal hemimegalencephaly with early myelination, Dandy-Walker variant, and lipoma. All of these cases had postpartum confirmation. The additional information changed the treatment in three of six patients (no intervention or elective abortion). CONCLUSIONS: In certain situations MR can add valuable information to that obtained by sonography in the evaluation of the fetal central nervous system.

Central Nervous System↗
PubMed1993

Structure-activity relationships of the antimalarial agent artemisinin. 1. Synthesis and comparative molecular field analysis of C-9 analogs of artemisinin and 10-deoxoartemisinin.

A series of C-9 beta-substituted artemisinin analogs (2-21) were synthesized via dianion alkylation of the total synthetic intermediate 57 followed by subsequent ozonolysis/acidification, or by alkylation of the enolate derived from (+)-9-desmethylartemisinin, 2. Inactive acyclic analogs 22 and 23 were synthesized by nucleophilic epoxide opening and the ring contracted analog 24 was prepared by an alternate route. 10-Deoxo-9-alkyl derivatives 68 and 70 were synthesized convergently from intermediates in the preparation of 9-alkyl derivatives. In vitro bioassay was conducted in W-2 and D-6 clones of drug resistant Plasmodium falciparum. Comparative molecular field analysis (CoMFA) of the 9-alkyl lactone derivatives provided a model with a cross-validated r2 = 0.793. Inclusion of inactive 1-deoxyartemisinin analogs 26-42 provided a model with a value of 0.857. The activities of a number of other analogs of divergent structure (43-56) were predicted with good accuracy using the CoMFA model.

Animals↗
PubMed1993

Identification of a proline residue as a transduction element involved in voltage gating of gap junctions.

Gap junction channels are structurally distinct from other ion channels in that they comprise two hemichannels which interact head-to-head to form an aqueous channel between cells. Intercellular voltage differences together with increased intracellular concentrations of H+ and Ca2+ cause closure of these normally patent channels. The relative sensitivity to voltage varies with the subunit (connexin) composition of the channels. The third of four transmembrane-spanning regions (M3) in connexins has been proposed to form the channel lining, and a global 'tilting' of the hemichannel subunits has been correlated with channel closure. But specific components involved in transduction of channel gating events have not been identified in either gap junctions or other ion channel classes (however, see model in ref. 5). We have examined a strictly conserved proline centrally located in M2 of connexin proteins. Mutation of this proline (Pro 87) in connexin 26 causes a reversal in the voltage-gating response when the mutant hemichannel is paired with wild-type connexin 26 in the Xenopus oocyte system. This suggests that the unique properties associated with this residue are critical to the transduction of voltage gating in these channels.

Amino Acid Sequence↗
PubMed1993

Temporal lobe atrophy on magnetic resonance imaging in the diagnosis of early Alzheimer's disease.

OBJECTIVE: To evaluate the use of simple ratings and linear measures of atrophy in the temporal lobe structures obtained with magnetic resonance imaging coronal scans in the diagnosis of early Alzheimer's disease. DESIGN: Prospective series. The National Institute for Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment. SETTING: Dementia study in a university hospital. SUBJECTS: Patients with Alzheimer's disease (n = 34), scoring 150 or more on the Extended Scale for Dementia, and age-matched healthy community volunteers (n = 39) who had both magnetic resonance imaging coronal scans and a psychometric assessment using the Extended Scale for Dementia within 6 months were included. MEASURES MAIN MEASURES: T1-weighted magnetic resonance imaging coronal scans, a 1.5-T system. The degree of atrophy rated (0 to 4) in both sides of the temporal neocortex, entorhinal cortex, hippocampal formation, temporal horns, third ventricle, lateral ventricles, and frontal and parietal cortex. Linear measures: the area of hippocampus and the maximal transverse width of temporal horns. RESULTS: Differentiation between patients with Alzheimer's disease and controls was limited by considerable variations in sensitivity and specificity. Receiver operating characteristics analysis revealed a clear order of discrimination, the entorhinal cortex and the temporal neocortex being the two best, followed by the temporal horns and hippocampal formation. For a given specificity of 90%, the corresponding sensitivity for the entorhinal cortex, temporal neocortex, temporal horns, and hippocampal formation was 95%, 63%, 56%, and 41%, respectively. Linear measures differed significantly but showed considerable overlap. CONCLUSION: The presence of rated atrophy in selected temporal structures makes the diagnosis of Alzheimer's disease more likely, but the absence does not rule out the possibility of early Alzheimer's disease.

Adult↗
PubMed1993

Enhancement in the safety of immune globulins prepared from high-risk plasma.

Hyperimmune gamma-globulins have proven efficacious in the prevention and treatment of viral infections, including those caused by hepatitis A and B viruses, cytomegalovirus, parvovirus. Interest in the prevention and/or treatment of infections caused by human immunodeficiency virus (HIV) has led to clinical trials with anti-HIV immune plasma and purified immune globulin prepared from donors who are actively infected with HIV. The handling and fractionation of this or other infectious plasma requires the construction and operation of virus containment facilities designed to protect fractionation employees and the immediate environment. This requirement would be reduced substantially by applying virucidal procedures prior to or during plasma pooling. We have shown that heating plasma at 56 degrees C for 1 h followed by treatment with 1% tri(n-butyl) phosphate (TNBP) and 1% Triton X-100 for 4 h at 30 degrees C resulted in the inactivation of > or = 10(12.1) tissue culture infectious doses (TCID50) of HIV. With this treatment, the recovery of IgG was 87 +/- 3%. Fractionation of treated plasma by cold ethanol precipitation proceeded normally, and overall recovery, purity, and potency against selected viral markers were unaffected. The additional treatment of plasma with 15 g/l Aerosil for 4 h at 45 degrees C removed 10(4.5) TCID50 of HIV but resulted in substantial IgG losses both prior to and following fractionation. We conclude that potentially infectious plasma can be treated at 56 degrees C for 1 h and by TNBP/Triton X-100 at 30 degrees C for 4 h prior to fractionation. These steps appear sufficient to assure safety and to permit routine fractionation of plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1993

Hel-N1: an autoimmune RNA-binding protein with specificity for 3' uridylate-rich untranslated regions of growth factor mRNAs.

We have investigated the RNA binding specificity of Hel-N1, a human neuron-specific RNA-binding protein, which contains three RNA recognition motifs. Hel-N1 is a human homolog of Drosophila melanogaster elav, which plays a vital role in the development of neurons. A random RNA selection procedure revealed that Hel-N1 prefers to bind RNAs containing short stretches of uridylates similar to those found in the 3' untranslated regions (3' UTRs) of oncoprotein and cytokine mRNAs such as c-myc, c-fos, and granulocyte macrophage colony-stimulating factor. Direct binding studies demonstrated that Hel-N1 bound and formed multimers with c-myc 3' UTR mRNA and required, as a minimum, a specific 29-nucleotide stretch containing AUUUG, AUUUA, and GUUUUU. Deletion analysis demonstrated that a fragment of Hel-N1 containing 87 amino acids, encompassing the third RNA recognition motif, forms an RNA binding domain for the c-myc 3' UTR. In addition, Hel-N1 was shown to be reactive with autoantibodies from patients with paraneoplastic encephalomyelitis both before and after binding to c-myc mRNA.

Animals↗
PubMed1993

Study on the macromolecular synthesis in aging mouse seminiferous tubules by light and electron microscopic radioautography.

Morphologic alternation and the changes of DNA, RNA and protein syntheses of the seminiferous tubules of aging mice were studied by light and electron microscopic radioautography. The morphology varied characteristically during the developmental periods. At embryonic and neonatal stages, the labelled myoid cells and Sertoli cells with 3H-thymidine were well observed, while at adult period, the labeling indices of both cells decreased to low levels. In contrast to this, the radioautograms showed that the gonocytes did not incorporate the labelled thymidine at embryonic day 19. As development proceeded to the 4th day after birth, the activity of DNA synthesis of gonocytes started. The labeling indices of spermatogonia reached the first peak at 3 weeks and were nearly constant thereafter. On the other hand, the activity of RNA synthesis of the cells in seminiferous tubules was not prosperous at embryonic day 19 and the neonatal stage. It was vigorous at adult and maintained a relatively high level at old period. The aging change of protein synthesis was detected in all kinds of the cells one hour after the 3H-leucine labeling. These results indicated that the old mice still kept adequate spermatogenesis. The Sertoli and myoid cells may play an important role in spermatogenesis in the whole life.

Aging↗
PubMed1993

Light microscopic radioautographic study on DNA synthesis in aging mice corneas.

The morphological change and DNA synthesis of the aging mice corneal cells were investigated by light microscopic radioautography after injection of tritiated thymidine. The result showed that the incorporation of tritiated thymidine in corneal cells changed with aging. The sites of tritiated thymidine incorporation were located in the epithelium from postnatal day 19 to 1 year after birth, in the stroma and endothelium from prenatal day 19 to postnatal day 8 only. The labeling index in the epithelial cells reached its highest value at 1 month after birth. Labelled stromal and endothelial cells reached their peaks simultaneously on the third day after birth and disappeared completely from postnatal 1 month onwards. The thickness of the cornea increased obviously at one month and there were no notable morphological change thereafter. Our investigation provides for the first time a systematic study on the age-related changes of DNA synthesis and construction in the aging mice corneas.

Aging↗
PubMed1993

Postnatal development and aging of esophageal epithelium in mouse: a light and electron microscopic radioautographic study.

DNA synthesis and fine structure of the esophageal epithelium of ddY mouse in different age groups, from neonatal to senescent, were investigated by light and electron microscopic radioautography after 3H-thymidine labeling in vitro. At 1-3 days after birth, the esophagus was lined with two cell types, ciliated and nonciliated cells. From 1 week on, ciliated cells could not be found. At 2 weeks, the superficial cells still possessed nuclei and short microvilli on the apical plasma membranes. From 1 month, the superficial cells became keratinized and the microvilli on the apical plasma membrane disappeared. With aging of the mice, the epithelia became markedly thick. These results show that disappearance of ciliated cells, keratinization of superficial cells and increase of the thickness are the main changes in structure of mouse esophageal epithelium from neonatal to senescent ages. By light microscopic radioautography, labelled cells were almost confined in the basal layer, regardless of the aging stages. The highest labeling index was recorded at 1 day after birth, then decreased with age. By electron microscopic radioautography, silver grains indicating DNA synthesis were observed in nuclei. As compared with those of unlabelled cells in the basal layer, the nuclei and nucleoli of labelled cells were larger, with fewer cell organelles. The present study provides, for the first time, the basic quantitative data regarding cell proliferation of mouse esophageal epithelium from neonatal to senescent stage.

Aging↗
PubMed1993

Radioautographic study on 3H-thymidine incorporation at different stages of muscle development in aging mice.

The DNA synthesis of mouse intercostal muscle from the 13th prenatal day through postnatal 24 months has been studied by light microscopic radioautography after the injection of 3H-thymidine. Chronological changes of labeling indices showed the highest value at E13, decreased gradually and reached almost 0% at 3 months after birth. We classified the embryonic muscle development into five stages, and the LI at stage I was the highest, the LI at stage II was significantly lower than that at stage I, the LI at stage IV was significantly higher than that at stage II, and the LI at stage V was significantly lower than that at stage IV. These changes accorded well with the primary and secondary myotube formation.

Aging↗
PubMed1992

Human infection by genetically diverse SIVSM-related HIV-2 in west Africa.

Our understanding of the biology and origins of human immunodeficiency virus type 2 (HIV-2) derives from studies of cultured isolates from urban populations experiencing epidemic infection and disease. To test the hypothesis that such isolates might represent only a subset of a larger, genetically more diverse group of viruses, we used nested polymerase chain reactions to characterize HIV-2 sequences in uncultured mononuclear blood cells of two healthy Liberian agricultural workers, from whom virus isolation was repeatedly unsuccessful, and from a culture-positive symptomatic urban dweller. Analysis of pol, env and long terminal repeat regions revealed the presence of three highly divergent HIV-2 strains, one of which (from one of the healthy subjects) was significantly more closely related to simian immunodeficiency viruses infecting sooty mangabeys and rhesus macaques (SIVSM/SIVMAC) than to any virus of human derivation. This subject also harboured multiply defective viral genotypes that resulted from hypermutation of G to A bases. Our results indicate that HIV-2, SIVSM and SIVMAC comprise a single, highly diverse group of lentiviruses which cannot be separated into distinct phylogenetic lineages according to species of origin.

Adult↗
PubMed1992

Cytoplasmic domain truncation enhances fusion activity by the exterior glycoprotein complex of human immunodeficiency virus type 2 in selected cell types.

To investigate the glycoprotein determinants of viral cytopathology, we constructed chimeric env genes between a noncytopathic strain of human immunodeficiency virus type 2 (HIV-2), designated HIV-2/ST, and a highly fusogenic and cytopathic variant derived from this virus. Expression of the resulting chimeric glycoproteins indicated that efficient syncytium formation in the human T-cell line Sup T1 mapped to the C-terminal region of the transmembrane (TM) glycoprotein subunit. In this region, the wild-type and cytopathic ST glycoproteins differed by only four amino acids and by the presence of a premature termination codon in the cytopathic variant. Subsequent site-directed mutagenesis indicated that the cytoplasmic domain truncation was responsible for the enhanced fusion activity. This modification, however, increased the fusion activity of the glycoprotein only in Sup T1 cells (in which the ST variant arose) but not in Molt 4 clone 8 or peripheral blood mononuclear cells. These observations indicate that the length of the cytoplasmic domain of the HIV-2 glycoprotein modulates the fusion activity of the exterior glycoprotein complex in a cell-specific manner. Such adaptability appears to permit the emergence of fusogenic variants during HIV-2 passage in vitro and may also regulate viral growth or cytopathic effects in selected cell types during natural infection in vivo.

Amino Acid Sequence↗
PubMed1992

[Study on casting precision of plat castable ceramic crowns].

The plat castable ceramic crown was made with investment material prepared in our college with our own casting technique by a Chinese-made casting machine. The accuracy and fitness of the crown were studied and appraised. Results show that the margin of fitness is 46 microns and that the cement film thickness of the dies in the spacer material group is 65.13 microns. Hence the results are satisfactory. The Plat castable ceramic crown might be used in clinical dentistry.

Crowns↗