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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 757 records · Page 42Linked to original sources
PubMed1993

Studies on oxygen transfer process in animal cell culture bioreactor.

The oxygen transfer rates were investigated systematically in the CellCul-20A bioreactor with the device of cage aeration in this paper. The temperature, rotating speed, aeration rate and foam breaker, which affected the rate of oxygen transfer were studied, respectively. The mass transfer rate increased significantly with the aeration while the foam breaker had a negative effect on kLa, especially in a cell culture medium with 5% (v/v) calf serum. The oxygen transfer coefficients of surface and deep aerations were correlated, based on the experimental data.

Air↗
PubMed1993

The cloning and sequencing of coat protein gene from beet necrotic yellow vein virus.

The beet necrotic yellow vein virus (BNYVV) isolate NM was isolated from sugarbeet infected with rhizomania in Inner Mongolia of China. The cDNA of BNYVV coat protein (CP) gene was amplified from the extracted RNA of BNYVV isolate NM by using the polymerase chain reaction (PCR) and cloned into pGEM-7zf(+). Its complete nucleotide sequence was determined by means of Sanger's dideoxy-mediated chain-termination method. The result shows that CP gene of BNYVV isolate has 567 nucleotides. It shares 98.8% and 96.7% identity with the CP gene of isolate F13 (report in reference [1]) in terms of amino acid and nucleotide sequence, respectively.

Amino Acid Sequence↗
PubMed1993

[Effects of oxyfedrine on high blood viscosity and myocardial necrosis induced by epinephrine and ice water stress in rats].

Acute high blood viscosity (HBV) and myocardial necrosis was established by epinephrine (Epi) and ice water stress in rats. Effects of iv oxyfedrine (Oxy) on HBV, plasma viscosity (PV), hematocrit, erythrocyte electrophoretic time (EET), and fibrinogenic viscosity (FV) were studied in model. Results showed that Oxy 1 mg.kg-1 iv markedly decreased the arterial and venous blood HBV at shear rates of 700 s-1 and 70 s-1, respectively (P < 0.01). There were significant differences in the alleviation of HBV among 3 groups (Oxy 0.01, 0.1, and 1 mg.kg-1 iv). The above doses markedly decreased the HBV, PV, and FV, and shortened the EET. Effects of iv Oxy on the myocardial necrosis rat model were scrutinized under the light and electron microscopes. Oxy iv 1 mg.kg-1.d-1 x 1, 3, and 5 d prevented or mitigated the occurrence and development of myocardial necrosis. The structure of heart mitochondria and myofibrils were clearly discernible. This action may be related to the alleviation of HBV by Oxy.

Animals↗
PubMed1993

Endoscopic variceal ligation. Experience in 78 patients.

Endoscopic variceal ligation (EVL) is a new alternative to sclerotherapy in the treatment of esophageal variceal hemorrhage, which results in strangulation, necrosis and scar formation of varices without systemic or local adverse effect. From May 1, 1991 through July 1, 1992, EVL was performed in 78 consecutive patients, in 35 of them it was performed during active massive bleeding, and active bleeding was controlled by the initial session in 31 patients. With repeated EVL treatment, 32 patients had their varices obliterated. The varices had reduced in size in other patients. No ligation-related complications were observed. This procedure is a safe, effective and rather simple method to treat esophageal varices, especially in patients with poor liver function and recurrent bleeding after devascularization or shunt surgery.

Adolescent↗
PubMed1993

Food efficiency in rats following brain lesions which affect target body size: implications on the set point for target size.

Target size, i.e. body size appropriate for age, may be reset by bilateral lesions of several brain areas. The mechanism for control of target body size is unknown, but some of the loci have marked effects on gustatory behavior and/or energy metabolism. We have tested the possibility that a disturbance in energy metabolism may be a common factor in resetting target size. Food efficiency for body weight gain and for metabolic size (the 0.75 power of body weight) was determined in rats that were experimentally stunted by neonatal head-irradiation or by bilateral electrolytic lesions produced soon after weaning in the dorsomedial hypothalamic nuclei (DMH) or the substantia nigra (SN). The irradiations were carried out in males and females; the surgical lesions were produced only in males. Observations were carried out from weaning through early adulthood. Subgroups of irradiated rats and controls were fasted for 48 hours at 40 days of age. Irradiated rats had reduced food efficiency for weight gain and for metabolic size, more marked in males than in females. DMH or SN lesions did not change food efficiency for weight gain. Food efficiency for metabolic size increased after DMH lesions and declined after SN lesions. During refeeding after a fast, irradiated rats showed a normal transient increase in food efficiency for weight gain, but not for metabolic size. The differences in food efficiency following different lesions tend to exclude altered energy metabolism as a common factor in the reset of target body size.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Morphological changes in the pituitary gland and ovary in testosterone-induced anovulatory rat treated with Chinese medicinal herbs].

Injection of testosterone propionate 1.25 mg were given to SD rats on 9 days of age, and fed with replenishing Kidney herbal decoction as well as with distilled water as control from 80 to 94 days of age. On 100 days of age, all the rats were sacrificed and the pituitary glands and ovaries were excised for examination. In the ovaries, increase in interstitial glands' count and lowering of lipid drop's quantity in cytoplasm of interstitial glandular cells were observed after the treatment, and intracellular "crinophagy" and "autophagy" disappeared in the pituitary gland. After treatment with replenishing Kidney drugs, ovarian estrogen receptors increased whereas the ovarian progesterone receptors raised even higher. It suggests that both ovaries and pituitary gland in testosterone induced anovulatory rats were affected by herbs of replenishing Kidney.

Animals↗
PubMed1992

Basal forebrain and anterior thalamic contributions to acetylcholinesterase activity in granular retrosplenial cortex of rats.

Histochemical studies demonstrate that granular retrosplenial cortex (cortical areas 29b and c) of the adult rat displays a characteristic laminar pattern of acetylcholinesterase (AChE) activity. While some AChE-positive axons are found in all cortical layers, most intense staining occurs in two bands that correspond to layers I and III. The present studies were directed toward identifying the neural systems underlying this AChE activity. Unilateral electrolytic or excitatory amino acid induced lesions of the basal forebrain, including the nucleus of the diagonal band, result in reductions of AChE staining throughout ipsilateral granular retrosplenial cortex; particularly noteworthy are the reductions in layer I and the deeper cortical layers. AChE staining remains in superficial layer I and in layer III. Placement of lesions in the anterior thalamus, including all of the anterior dorsal nucleus, results in reduction of AChE histochemical staining in the outer part of layer I and especially in layer III. Staining remains in much of layer I and in the deepest band of layer III. Placement of electrolytic lesions in the hypothalamus or the midbrain tegmentum produce no detectable change in the pattern of AChE in retrosplenial cortex. These results indicate that AChE activity in granular retrosplenial cortex is found primarily within afferent axons from the basal forebrain system and from anterior dorsal thalamus, and these two systems of afferents display distinct laminar patterns of termination.

Acetylcholinesterase↗
PubMed1992

Transition from developing to mature patterns of acetylcholinesterase activity in rat visual cortex: implications for the time-course of geniculocortical development.

Patterns of acetylcholinesterase (AChE) histochemical staining in cortical area 17 differ in infant and mature rats. In infants, intense AChE activity is seen as a band corresponding to layer IV and deep layer III of the visual cortex, and this staining is associated with terminal fields of geniculocortical neurons. In adult animals, AChE activity is densest in deep layer IV and layer V and is associated with projections originating in the basal forebrain. The present study investigated the transition from developing to mature patterns of AChE staining in visual cortex. Unilateral lesions were placed in either the lateral geniculate body or the basal forebrain of rats postnatal days 8 (P8) to adulthood; the effects of these lesions on patterns of AChE activity in visual cortex were studied with histochemical techniques and optical densitometry. Lesions involving the lateral geniculate body markedly reduce AChE activity in visual cortex of P12 rats, had moderate effects in P20 rats, and had no apparent effect on AChE activity of visual cortex of rats aged P40 and older. Lesions of basal forebrain had little effect on AChE activity in visual cortex of P12 animals, increasing effect in P15-35 rats, and eliminated much of AChE staining in visual cortex of adults. The period of transition from developing to mature patterns of AChE activity in visual cortex of animals bilaterally enucleated at birth was not different from the period of transition in normally sighted animals. These data indicate that mature patterns of AChE activity in visual cortex are not achieved until well into the second month of life. If transient AChE expression is characteristic of geniculocortical neurons during the period of time in which axons are proliferating within visual cortex, then these data indicate that geniculocortical connections may be forming well into the second month of life in the rat.

Acetylcholinesterase↗
PubMed1992

Isolation and amino acid sequences of opossum vasoactive intestinal polypeptide and cholecystokinin octapeptide.

Evolutionary history suggests that the marsupials entered South America from North America about 75 million years ago and subsequently dispersed into Australia before the separation between South America and Antarctica-Australia. A question of interest is whether marsupial peptides resemble the corresponding peptides of Old or New World mammals. Previous studies had shown that "little" gastrin of the North American marsupial, the opossum, is identical in length to that of the New World mammals, the guinea pig and chinchilla. In this report, we demonstrate that opossum cholecystokinin octapeptide, like that of the Australian marsupials, the Eastern quoll and the Tamar wallaby, is identical to the cholecystokinin octapeptide of Old World mammals and differs from that of the guinea pig and chinchilla. However, opossum vasoactive intestinal polypeptide differs from the usual Old World mammalian vasoactive intestinal polypeptide in five sites: [sequence; see text].

Amino Acid Sequence↗
PubMed1992

Effect of activin A on globin gene expression in purified human erythroid progenitors.

The regulatory control of human erythropoiesis through a purified protein, activin A, was examined. Previous studies using mixed populations of bone marrow cells suggested that activin A has an indirect effect on cellular proliferation and DNA synthesis of erythroid progenitors through the mediation of accessory cells. In present studies, the cultures of purified erythroid progenitors were used to examine the effect of activin A on globin gene expression. Human erythroid burst-forming units (BFU-E) were partially purified from peripheral blood, and after 8 days of culture the cells generated consisted mainly of erythroid colony-forming units (CFU-E). It was found that the subsequent 7-day cultures of these purified progenitors yielded similar numbers and size distributions of erythroid colonies, regardless of the presence of activin A in the cultures. In addition, these erythroid progenitor cells were responsive, in terms of stimulation of DNA synthesis, to the addition of erythropoietin, but not to treatment by activin A. Therefore, once the erythroid progenitors are depleted of accessory cells, activin A has little effect on both the proliferation and the DNA synthesis of these progenitors. However, when these purified erythroid progenitors were cultured in the presence of activin A, the levels of all alpha, beta, and epsilon globin transcripts and hemoglobins were significantly increased. In addition, disuccinimidyl suberate was found to chemically cross-link 125I-activin A to cell surface binding proteins (45 to 54 Kd) in both purified erythroid progenitors and K562 cells. The labeling of these binding proteins was specifically inhibited by the presence of unlabeled activin A, but not transforming growth factor-beta. These results suggest that, in addition to its indirect effect on DNA synthesis and cellular proliferation of erythroid progenitors, activin A directly affects the levels of globin mRNAs and hemoglobins in developing human erythroid cells through its specific surface binding receptor(s).

Activins↗
PubMed1992

Regulation of globin gene expression in human K562 cells by recombinant activin A.

Recent studies indicate that a purified protein, activin A, belongs to the transforming growth factor beta (TGF-beta) superfamily. Similar to TGF-beta, activin A can have different biologic activities, depending on the target tissues. We used recombinant activin A to demonstrate a possible regulatory role of this protein in modulating human erythroid differentiation in the human erythroid cell line, K562. Using genomic probes containing the second exon of alpha, beta, gamma, and epsilon globins, relative abundance of various types of globin transcripts in untreated and activin-treated K562 cells was examined with S1 nuclease analysis. Despite considerable homology amongst various globin sequences, these globin probes were highly specific for their unique mRNA species in the analyses. It was shown that the abundance of specific globin probe fragments for gamma and epsilon globins (209 nucleotides) as well as alpha (180 nucleotides), which were protected from S1 digestion, increased many fold in K562 cells treated with activin A. In contrast, there were no specific transcripts of beta globin detected in either the control or activin-treated cells. The increases in the level of fetal and embryonic beta-like and alpha globin transcripts also confirmed earlier studies of Northern and slot-blot analyses using globin cDNA as probes. In addition, nuclear run-off transcription assay using isolated nuclei indicated that most of the increase in the globin transcripts after activin treatment could be attributed to the stimulation of transcription rate for globin genes. Transient transfection assays also provide evidence that activin A significantly stimulated transcriptional activity of an epsilon globin promoter in K562, but not in the nonerythroid Chinese hamster ovary cells. Therefore, it was concluded that activin A exerts its effects on globin gene expression at the level of transcription in erythroid cells.

Activins↗
PubMed1992

Activin A-induced differentiation in K562 cells is associated with a transient hypophosphorylation of RB protein and the concomitant block of cell cycle at G1 phase.

The human erythroleukemic cell line, K562, can be induced to differentiate by the addition of activin A, a newly purified protein belonging to the TGF-beta 1 family. The present studies used flow cytometric cell cycle analysis, indirect immunofluorescence staining of the proliferating cell nuclear antigen (PCNA), and thymidine incorporation assay of cell proliferation to study the effects of activin A on the cell cycle during differentiation in K562 cells. Activin A-treated K562 cells were found to undergo a transient block in cell cycle, temporarily halting progression from G1 to S phase. The latter can be observed after approximately 24 hr of incubation with activin A and then disappears after this early stage of induction of differentiation. Cell cycle kinetics analysis using synchronized K562 cells also confirms that in the presence of activin A, K562 cells progress normally through various phases of cell cycle, except that there is prolongation of the G1 phase between 10 to 24 hr of culture. Furthermore, this transient arrest in G1 is correlated with dephosphorylation of a nucleoprotein, the RB gene product, which occurs within 9-24 hr of incubation with activin A; and phosphorylation of RB protein then develops afterward. In addition, these cell cycle-related events are observed to occur earlier than the accumulation of hemoglobins in K562 cells. It is concluded that transient dephosphorylation of RB protein and prolongation of G1 phase of cell cycle precede and accompany erythroid differentiation caused by activin A and chemical inducers, thus constituting part of the mechanism for induction of differentiation in the erythroleukemia cells.

Activins↗
PubMed1992

Assignment of the human glycogen debrancher gene to chromosome 1p21.

Glycogen debranching enzyme is a monomeric protein containing two independent catalytic activities of glycantransferase and glucosidase that are both required for glycogen degradation. Its deficiency causes type III glycogen storage disease. A majority of the patients with this disease have deficient enzyme activity in both liver and muscle (type IIIa) but approximately 15% of them lack enzyme activity only in the liver (type IIIb); however, the enzyme is a monomer and appears to be identical in all the tissues. The cDNA coding for the complete human muscle debranching enzyme has recently been isolated. Using the cDNA clones, the debrancher gene was localized to human chromosome 1 by somatic cell hybrid analysis. Regional assignment to chromosome band 1p21 was determined by in situ hybridization. Mapping of the debrancher gene to a single chromosome site is consistent with our hypotheses that a single gene encodes both liver and muscle debrancher protein.

Animals↗