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Biomedical subjects

B Yao

Publications and source records attributed to B Yao.

62 records · Page 4Linked to original sources
PubMed1993

Bicarbonate transport by rabbit duodenum in vitro: effect of vasoactive intestinal polypeptide, prostaglandin E2, and cyclic adenosine monophosphate.

BACKGROUND: Duodenal surface cells secrete bicarbonate that provides a barrier against injury. The current experiments were performed to identify duodenal bicarbonate regulatory and transport pathways. METHODS: Rabbit proximal duodenal mucosa were mounted in chambers under short-circuited conditions. Bicarbonate transport, short-circuit current (Isc), and potential difference (PD) were quantitated in response to prostaglandin E2 (PGE2), vasoactive intestinal polypeptide (VIP), and dibutyryl cyclic adenosine monophosphate (db-cAMP). Anoxia (N2), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and Cl(-)-free solutions, ouabain, and Na-free solutions were also studied, as was the effect of VIP and PGE2 on duodenocyte cAMP. RESULTS: PGE2, VIP, db-cAMP, and theophylline significantly increased bicarbonate secretion, Isc, and PD. Ouabain, Na(+)-free bathing solutions, and anoxia (N2) inhibited the responses. DIDS and Cl(-)-free solutions abolished the PGE2-induced response, reduced the response to VIP by about 50%, and had no effect on the response to db-cAMP. After PGE2 and VIP, cAMP concentration increased, yet was likely independent of bicarbonate secretion. CONCLUSIONS: Mammalian duodenal HCO3- transport requires Na+, Na+/K(+)-adenosine triphosphatase and O2-dependent metabolic pathways and is stimulated by PGE2, VIP, and cAMP, acting by distinct pathways.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

[The characters on histopathological changes in dental fluorosis]

The microradiography SEM and TEM were used ton observe histopathological changes in dental fluorasis with various degrees in this study.The characters of histopathological changes of dental fluorasis are:(1) the lesios appear in exterior layer of enamel,not excess one third enamel.(2)the future of the lesion is enamel-hypoplasia,enamel rods were hypomineralized.the space among enamel rods widen and form some cavities.There are a lot of spaces in intercrystlines.Many micropores and injures exhibit on enamel surface.(3)the clinic severe degree of lesion is similar to the histopathological changes.It could be indicated using the Dean's and the TF index.

Journal Article↗
PubMed1989

Primary structure of the maltose-permease-encoding gene of Saccharomyces carlsbergensis.

The MAL6 locus of Saccharomyces consists of a cluster of at least three genes: MAL6R encodes a positively acting regulatory protein; MAL6S encodes maltase; and MAL6T encodes maltose permease. A MAL6 Eco RI fragment, E1, that encompasses most of the MAL6T gene except for the first 90 bp of the ORF at its 5' end (sequenced previously), was cloned into a pGEM-Blue vector. Sequential deletions were generated and then sequenced. The MAL6T gene has a putative ORF of 1845 bp. The amino acid composition and sequence of the deduced protein shows that it is highly hydrophobic and has a size of 68.2 kDa. Computer-generated hydropathy profiles suggest that the MAL6T protein may have up to nine membrane-spanning regions. Generation of functional fusions of the MAL6T promoter region to Escherichia coli lacZ-containing vectors indicates that sequences in the intergenic region are responsible for the induction of MAL6T by maltose and for its carbon catabolite repression. We also demonstrated the suitability of E. coli lacZ as a reporter gene for promoter activity studies in yeast.

Amino Acid Sequence↗
PubMed1988

Release of prolactin is independent of the secretion of thyrotrophin-releasing hormone into hypophysial portal blood of sheep.

In order to determine whether pituitary prolactin release was directly related to the secretion of TRH into hypophysial portal blood, serial portal and jugular venous blood samples were collected from seven lactating and three non-lactating ewes. In another experiment, samples were collected from five ovariectomized ewes while being exposed to an audio-visual stress and then later administered with chlorpromazine. Secretion of TRH was pulsatile in all ewes and independent of prolactin secretion; TRH pulses coincided with significant increases in prolactin secretion in only 15% of cases and only 29% of prolactin pulses were associated with TRH pulses. Sixty-seven per cent of suckling bouts were associated with increases in prolactin secretion, but only 22% of these were associated with significant increases in TRH secretion. Chlorpromazine increased prolactin levels fourfold but did not affect portal concentrations of TRH. Audio-visual stress was not a reliable method of causing prolactin release in this model. Mean portal concentrations of TRH and jugular concentrations of prolactin were not significantly correlated. These results show that hypothalamic TRH and pituitary prolactin are secreted independently in the sheep, implying that increases in prolactin release caused by suckling or chlorpromazine are not the direct result of increased TRH secretion.

Animals↗
PubMed1987

GnRH secretion throughout the ovine estrous cycle.

In order to define the patterns of gonadotropin-releasing hormone (GnRH) secretion during the estrous cycle of the sheep we sampled hypophysial portal blood from conscious animals on day 1 of the cycle (n = 1), during the luteal phase (n = 8), during the follicular phase (n = 6) and during the preovulatory luteinizing hormone (LH) surge (n = 6). At the same time, we sampled jugular blood to measure plasma LH concentrations. During day 1 we noted regular GnRH pulses, whereas GnRH pulse amplitude and frequency were more variable in the luteal phase of the cycle. In the transition from the luteal phase to the follicular phase the GnRH pulse frequency increased and the amplitude decreased. Around the time of the LH surge we noted 3 types of secretory profiles for GnRH. In one sheep (type 1) there was a large GnRH pulse at the onset of the LH surge followed by very little activity during the surge. In two sheep (type 2) the GnRH profile did not change between the late follicular phase and the onset of the LH surge. In the remaining three sheep (type 3) there was a clear increase in the secretion of GnRH at the onset of the LH surge. With the exclusion of the type 1 sheep the GnRH pulse frequency was maximal (2 pulses/h) at the time of the LH surge; average portal GnRH levels were also maximal at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

The effect of chymotrypsin on the determination of total alpha-glucosidase activity in seminal plasma and the correlation between alpha-glucosidase level and semen parameters.

To evaluate the effect of chymotrypsin on the examination of alpha-glucosidase activity in seminal plasma, thirty-nine samples of fresh liquefied semen with or without chymotrypsin and forty-eight samples of fresh un-liquefied semen with chymotrypsin were determined for the total alpha-glucosidase activity in seminal plasma. The total alpha-glucosidase level of each sample was assayed by the method of glucose oxidase. The correlations between alpha-glucosidase level and semen parameters, including semen volume, pH, sperm concentration, grade a and b motility and total motility, were analyzed with SPSS 11.0 software. The results showed that chymotrypsin had no effect on seminal alpha-glucosidase activity determination. Chymotrypsin could improve the liquefaction for un-liquefied semen, and there was no significant difference of alpha-glucosidase activity between liquefied and un-liquefied semen samples. There were significantly positive correlations between seminal alpha-glucosidase activity (U/ml) and sperm concentration (r = 0.338, p = 0.015) and between total alpha-glucosidase activity (U/ejaculate) and semen volume (r = 0.677, p = 0.000). However, there was no significant correlation between alpha-glucosidase level (U/ml) and semen volume, pH, sperm motility or grade a and b motility (r = -0.234 approximately 0.077, p = 0.099 approximately 0.993). The data indicated that chymotrypsin could be added into the un-liquefied semen samples for alpha-glucosidase activity determination, and there were different correlations between seminal alpha-glucosidase level and various semen parameters.

Chymotrypsin↗
PubMedDate not supplied

Impaired motor learning and diffuse axonal damage in motor and visual systems of the rat following traumatic brain injury.

Cognitive-motor functioning or motor skill learning is impaired in humans following traumatic brain injury. A more complete understanding of the mechanisms involved in disorders of motor skill learning is essential for any effective rehabilitation. The specific goals of this study were to examine motor learning disorders, and their relationship to pathological changes in adult rats with mild to moderate closed head injury. Motor learning deficits were determined by comparing the ability to complete a series of complex motor learning tasks with simple motor activity. The extent of neuronal damage was determined using silver impregnation. At all post-injury time points (day 1 to day 14), statistically significant deficits were observed in parallel bar traversing, foot placing, ladder climbing, and rope climbing. Performance improved with time, but never reached control levels. In contrast, no deficits were found in simple motor activity skills tested with beam balance and runway traverse. Histologically, axonal degeneration was widely distributed in several brain areas that relate to motor learning, including the white matter of sensorimotor cortex, corpus callosum, striatum, thalamus and cerebellum. Additionally, severely damaged axons were observed in the primary visual pathway, including the optic chiasm, optic tract, lateral geniculate nuclei, and superior colliculus. These findings suggest that motor learning deficits could be detected in mild or moderate brain injury, and this deficit could be attributed to a diffuse axonal injury distributed both in the motor and the visual systems.

Animals↗