Biomedical subjects

B Yao

Publications and source records attributed to B Yao.

At least 19 recordsLinked to original sources

PubMed2001

Immunohistochemical and in situ hybridization studies of gonadotropin releasing hormone (GnRH) and its receptor in rat digestive tract.

GnRH(LH-RH) is first discovered in the hypothalamus and found to have a role in regulation of reproduction. With the study on it deepening, GnRH was demonnstrated that it also exists in a number of organs beyond the hypothalamus and acts on extrapituitary organs. To study whether digestive tract synthesizes GnRH and its receptor and, if it does, by what cells. In the experiment, the locallizations of GnRH and its receptors in rat digestive tract were studied using immunohistochemistry and in situ hybridization. The parietal cells of gastric gland, the villous and glandular epithelium in small and large intestine and parasympathetic ganglion cells of myenteric plexus showed GnRH immunoreactivity; GnRH mRNA hybridization signal was detected. The epithelium of gastric pit and the cells above in digestive tract showed GnRH receptor immunoreactivity; GnRH receptor mRNA hybridization signal was detected. The immunoreactive and signal materials distributed in cytoplasm of all positive cells, with nuclei being immunonegative and with no hybridization signal. These results suggested that the digestive tract can produce GnRH and express GnRH receptor; GnRH may also be a gastrointestinal hormone.

Animals↗

PubMed2001

Presence of gonadotropin-releasing hormone (GnRH) and its mRNA in rat pancreas.

Gonadotropin-releasing hormone (GnRH) has been reported to exist in many non-hypothalamic tissues, such as the placenta, gonads, and mammary glands, while there still have been no reports concerning the existence and expression of GnRH in the mammalian digestive system. Immunocytochemistry and in situ hybridization results show that GnRH molecule and GnRH mRNA are both exclusively distributed in exocrine pancreas, and RT-PCR result further proves that GnRH transcription units do exist in the pancreas, which possess the same sequence as the hypothalamus GnRH mRNA. Quantitative analysis indicates that mRNA levels in rat pancreas remain at a low level (less than 10% of that in hypothalamus) without sexual or developmental difference. This is the first report suggesting the existence and gene expression of GnRH in rat pancreas.

Animals↗

PubMed2001

Neuron tolerance during hydrocephalus.

Whether or not neuron death plays a major role in pathophysiology during hydrocephalus is not well known. The goals of this study were to determine if neural degeneration occurred during hydrocephalus, and to determine if neuron tolerance developed during this pathophysiologic procedure.Neural damage as visualized by a sensitive staining technique, silver impregnation, was observed in three experimental groups: (1) adult hydrocephalic rats induced by kaolin injection into the cisterna magna, (2) adult rats with chronic hydrocephalus for 10 weeks subjected to acute forebrain ischemia induced by four-vessel occlusion, and (3) adult rats without hydrocephalus subjected to acute forebrain ischemia. The magnitude of hydrocephalus was also evaluated during this time. In mild or moderate hydrocephalus, little cell death was found. In severe hydrocephalus, axon and neuropil degeneration was extensively distributed, but cell death was still rarely observed. Although some neuron degeneration was found after acute forebrain ischemia in hydrocephalic rats, the extensive cell death in cortical layers III and V, and in hippocampal areas CA1 and CA4 that is commonly observed in the ischemic brain without hydrocephalus, was not seen. This study suggests that neuron death was not a major pathological change in the brain during hydrocephalus, with cerebral ventricles being enlarged during the development of hydrocephalus. Less neuron death in hydrocephalic rats after acute forebrain ischemia suggests that neuronal tolerance to ischemia occurs during hydrocephalus.

Animals↗

PubMed2001

Accuracy and reproducibility of coronary flow rate assessment by real-time contrast echocardiography: in vitro and in vivo studies.

Real-time myocardial contrast echo (MCE) provides the potential to assess myocardial blood flow from time-intensity refilling curves after high-energy bubble destruction. This study validated the accuracy of this approach and the effect of specific examination variables and instrument settings on results. The effects of examination depth and angle as well as dynamic range, pulse repetition frequency, and line density were assessed with the use of in vitro incremental flow rates produced in an in vitro tissue phantom. In vivo recordings of real-time imaging with an infusion of a contrast agent (Optison) were obtained in 7 open-chest dogs with graded left anterior descending artery stenosis at baseline and during adenosine hyperemia, and were compared with flow probe measurements. After bubble destruction, time-intensity data were fitted to an exponential function, and the rate of intensity increase (b) and peak plateau intensity (A) were derived from refilling curves. In vivo real-time values for b, but not A, correlated closely with flow probe measures (r = 0.93). A similar correlation for b was observed in vitro (r = 0.98). The correlation between flow rate and b was influenced by several examination variables, including depth, angle, and instrument settings. Real-time MCE provides accurate quantification of coronary flow by assessing the rate of microbubble refilling. However, this parameter may be affected by several examination and instrument variables. Therefore, real-time MCE refilling measures are best applied by comparing baseline values with those of stress studies.

Animals↗

PubMed2001

Electrophysiologic and antiarrhythmic effects of the new class III antiarrhythmic drug KCB-328 in experimental canine atrial flutter.

BACKGROUND: The electrophysiologic and antiarrhythmic effects of a new class III antiarrhythmic drug (KCB-328), a delayed rectifier potassium current (IKr) blocker with minimal reverse use-dependent effect on atrial repolarization, were evaluated in the canine night atrial crush-injury model of atrial flutter (AFL). METHODS: Ten anesthetized, open-chest dogs, were studied after right atrial crush-injury. Atrial effective refractory period (ERP), conduction velocity (CV), wavelength, and dispersion of refractoriness were determined during programmed stimulation (S1S2 at S1S1 = 200, 300, 400, and 500 msec) at four sites via a mapping plaque sutured on the right atrial free wall. Right and left ventricular ERP were similarly measured at single sites. Electrophysiological parameters were determined at baseline and following sequential cumulative doses of KCB-328 (10, 30, 100, and 300 microg/kg). RESULTS: Sustained AFL was inducible in 7/10 dogs by rapid pacing following baseline electrophysiologic measurements. KCB-328 significantly prolonged sinus cycle length, but had no effect on PR interval, and prolonged QTc only at the highest dose level. KCB-328 significantly prolonged atrial ERP and wavelength and ventricular ERP, and significantly reduced dispersion of atrial refractoriness. KCB-328 significantly prolonged AFL cycle length, and increasing doses progressively terminated sustained AFL and prevented its reinduction by pacing. No adverse hemodynamic or ventricular proarrhythmic effects were observed. CONCLUSIONS: The electrophysiologic profile of KCB-328 in this canine model of AFL, particularly its lack of reverse use-dependent effect on atrial refractoriness, suggests that it may have significant antiarrhythmic potential in treatment of atrial arrhythmias.

Animals↗

PubMed2001

Axonal damage associated with enlargement of ventricles during hydrocephalus: a silver impregnation study.

Motor and cognitive deficits are commonly associated with hydrocephalus. Although the mechanisms responsible for these impairments have not been confirmed, neuronal cell death and axon degeneration may play an important role, and have long lasting consequences on neuronal connectivity. The goal of this study was to determine if neural degeneration occurred during hydrocephalus in structures anatomically related to cognitive motor functioning, namely, the sensorimotor cortex, neostriatum, hippocampus and corpus callosum. Neural damage, as visualized by silver staining, was examined in adult rats 2-10 weeks after obstructive hydrocephalus was induced by kaolin injection into the cisterna magna. In mild or moderate hydrocephalus, mostly occurring 2-6 weeks after kaolin injections, silver-labeled axons were scattered in the white matter of the sensorimotor cortex, corpus callosum, neostriatum, and hippocampus. In severe hydrocephalus, 10 weeks after kaolin injections, axon degeneration was more extensive in these areas, as well as in layers IV through VI of the sensorimotor cortex. Axons in the subiculum and the fimbria were heavily labeled, suggesting damage to hippocampal afferent and efferent fibers. In contrast, neuron cell death was rarely observed at any stage of hydrocephalus. The major pathological change of brain regions involved in motor and learning functions during hydrocephalus is axon degeneration, and this degeneration is correlated with an enlargement of the cerebral ventricles.

Animals↗

PubMed2001

[Cloning of neutral phytase gene nphy from Bacillus subtilis and its expression in Escherichia coli].

The gene encoding the neutral phytase nphy was cloned from Bacillus subtilis by polymerase chain reaction (PCR). Nucleotide sequence analysis of nphy revealed the presence of an open reading frame of 1152 bp coding for 383 aa. The start codon was followed by a sequence coding for a putative signal peptide of 26 aa in length. The nphy without original signal peptide encoding sequence was cloned into E. coli expression plasmid pTYB40. The result of SDS-PAGE of the phytase expressed in E. coli showed that the nphy had been overexpressed. The expressed phytase was over 40% of the total soluble protein of E. coli, and has normal bioactivity.

6-Phytase↗

PubMed2001

Correlation between decrease of 11beta-hydroxysteroid dehydrogenase activity and hypokalemia induced by furosemide in rats.

AIM: To investigate the correlation between decrease of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity and hypokalemia induced by furosemide (Fur) in rats. METHODS: SD rats were given single dose or successive doses of Fur by gavage. The activity of 11beta-HSD was evaluated by measuring the ratio of 11-dehydrocorticosterone (A) and corticosterone (B) in urine and conversion rate of B to A in renal cortex microsome preparation was determined with HPLC. RESULTS: After giving single dose of Fur (40, 100, and 250 mg/kg) or multiple doses of Fur (10, 20, and 100 mg/kg, bid x 20 d), the ratio of A/B was reduced by 29.0 %, 58.6 %, and 60.9 % at 0 - 2 h; 14.4 %, 36.0 %, and 44.9 %, respectively; the conversion rate of B to A was decreased by 29 %, 33 %, and 37 %; 6 %, 17 %, and 23 %, respectively. The serum potassium was significantly reduced by multiple doses of Fur (20 and 100 mg/kg, bid x 20 d) (P < 0.01). The reduction in serum potassium was positively correlated with the lowering of A/B ratio and the conversion of B to A (P < 0.01). CONCLUSION: The inhibition of renal 11beta-HSD activity may be another new biochemical mechanism for hypokalemia induced by Fur.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗

PubMed2001

[GATA-2 gene expression in leukemia patients and its significance].

OBJECTIVE: To investigate GATA-2 gene expression in leukemia patients and its clinical significance. METHODS: GATA-2 gene transcripts were detected by reverse transcriptase polymerase chain reaction (RT-PCR), and bcr/abl or PML/RAR alpha transcripts were detected in patients with chronic myeloid leukemia (CML) and acute promyelocytic leukemia (APL), respectively. RESULTS: The GATA-2 transcripts were revealed in 93% of acute myeloid leukemia (AML), in 70% of acute lymphoblastic leukemia (ALL), and 83% of CML patients, but not in normal bone marrow and peripheral blood cells. GATA-2 expression in remission patients was similar to newly diagnosed or relapsed patients. In post-transplantation patients, GATA-2 expression was significantly decreased. In these cases GATA-2 transcripts could be detected with bcr/abl fusion gene disappeared in 2 of 12 CML, whereas neither GATA-2 nor PML/RARalpha transcripts could be detected in APL. CONCLUSION: GATA-2 transcripts was highly expressed in leukemia patients and had no change in remission but significantly decreased in post-transplantation patients. Detection of GATA-2 expression would give information about the residual leukemia stem cells.

Bone Marrow Cells↗

PubMed2001

[Purification and properties of neutral phytase form Bacillus subtilis].

A strain Bacillus subtilis producing neutral phytase was screened from soil. The protein of phytase was purified by HPLC. Optimal pH value and temperature of the phytase for its activity were 7.5 and 55 degrees C, respectively. The Km values of the phytase for dodecasodium phytate under 37 degrees C was 0.19 mmol/L. The molecule weight of the phytase protein was determined as about 45 kD by SDS-PAGE. The N-terminal amino acids sequence of the phytase protein was determined as Lys-His-Lys-Leu-Ser-Asp-Pro-Tyr-His-Phe-Thr by amino acids sequence analysis.

6-Phytase↗

PubMed2000

[Molecular biology and gene engineering of phytase].

Phytase is a new-style enzyme used in monogastric animal feed. The addition of phytase to feed can increase phosphorus availability, decrease environmental phosphorus pollution and improve the performance of animal. This paper reviews the research progress and trend in recent studies related to molecular biology and gene engineering of phytase.

6-Phytase↗

PubMed2000

[A study on screening and high density cell cultivation of a yeast strain Kluyveromyces with high inulinase yielding and its enzymology properties].

A yeast strain Kluyveromyces with high inulinase yield was screened. The highest inulinase activity of 288.78 u/mL was reached when a high cell density cultivation method was developed for inulinase production. It was 6.8 times higher than the highest level reported in the same species. The activity ratio of its inulinase to invertase was 1/24.72, the Km values were 13.3 mmol/L and 62.6 mmol/L when inulin and sucrose were used as substrate, respectively; The optimum pH value was 4.4, this enzyme also showed a good pH adaptability and stability, i.e. more 90% of the highest level was maintained between pH 3.8 and 5.6; The optimum reaction temperature was 55 degrees C, higher activity was maintained between 50-57.5 degrees C, its half life period was 16 hours at 55 degrees C; It was found for the first time that addition of magnesium ion into the reaction system increased the enzyme activity by 11%.

Cells, Cultured↗

PubMed2000

[Insect-resistant transgenic poplar expressing AaIT gene].

Insect-specific scorpion neurotoxin AaIT gene inserted into a binary vector was transferred into a hybrid poplar clone N-106(P. deltoides x P. simonii) growing in the Southern of China. We obtained sixty-two regenerated plants by Agrobacterium tumefaciens transferring system. PCR and PCR-Southern analysis showed that AaIT gene was incorporated into the genome of some recovered poplar plants. One of the transformed plants named A5 was significantly resistant to feeding by first instar larvae of Lymantria dispar, compared with the untransformed control plant. It caused a decrease in leaf consumption by larvae, a lower larval weight gain and a higher larval motality rate of Lymantria dispar. ELISA analysis proved that AaIT gene was expressed in this transfomed poplar plant.

Animals↗

PubMed2000

[Does ureteroscopy still play a role in the treatment of ureteral calculi?].

OBJECTIVES: To evaluate the results obtained by ureteroscopy to treat ureteric stones and the related complications. MATERIALS AND METHODS: 74 ureteroscopies were studied retrospectively, including 62 cases of pelvic ureteric stones. In situ fragmentation was necessary in 28.4% of cases. Success was defined as the absence of stones for one month after ureteroscopy. Success rates were analysed according to size and site of the stone, the need for fragmentation and the patient's sex. RESULTS: Morbidity was 6.8%. Success was obtained in 60.8% of cases: 72.7% in women and 55.8% in men. The mean diameter of successfully treated stones was statistically smaller (6.2 +/- 2.1 mm) than that of stones with a poor result (7.8 +/- 3.7 mm) (p = 0.044, Spearman). CONCLUSIONS: The size and site of the stone and the patient's sex influence the results of ureteroscopy. Ureteroscopy for stone disease remains a topical modality after failure of extracorporeal lithotripsy, but also in the case of poor access of an effective lithotriptor.

Adult↗

PubMed1999

Structure/function of the beta-barrel domain of F1-ATPase in the yeast Saccharomyces cerevisiae.

The first 90 amino acids of the alpha- and beta-subunits of mitochondrial F1-ATPase are folded into beta-barrel domains and were postulated to be important for stabilizing the enzyme (Abrahams, J. P., Leslie, A. G., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628). The role of the domains was studied by making chimeric enzymes, replacing the domains from the yeast Saccharomyces cerevisiae enzyme with the corresponding domains from the enzyme of the thermophilic bacterium Bacillus PS3. The enzymes containing the chimeric alpha-, beta-, or alpha- and beta-subunits were not functional. However, gain-of-function mutations were obtained from the strain containing the enzyme with the chimeric PS3/yeast beta-subunit. The gain-of-function mutations were all in codons encoding the beta-barrel domain of the beta-subunit, and the residues appear to map out a region of subunit-subunit interactions. Gain-of-function mutations were also obtained that provided functional expression of the chimeric PS3/yeast alpha- and beta-subunits together. Biochemical analysis of this active chimeric enzyme indicated that it was not significantly more thermostable or labile than the wild type. The results of this study indicate that the beta-barrel domains form critical contacts (distinct from those between the alpha- and beta-subunits) that are important for the assembly of the ATP synthase.

Amino Acid Sequence↗

PubMed1999

Organization of geniculate and trigeminal ganglion cells innervating single fungiform taste papillae: a study with tetramethylrhodamine dextran amine labeling.

Single gustatory nerve fibers branch and innervate several taste buds. In turn, individual taste buds may receive innervation from numerous gustatory nerve fibers. To evaluate the pattern of sensory innervation of fungiform papilla-bearing taste buds, we used iontophoretic fluorescent injection to retrogradely label the fibers that innervate single taste papillae in the hamster. For each animal, a single taste papilla was injected through the gemmal pore with 3.3% tetramethylrhodamine dextran amine. Fungiform papillae either at the tongue tip (0.5-1.5 mm from the tip) or more posteriorly (1.5-3.0 mm from the tip) were injected. After one to seven days survival, the geniculate and trigeminal ganglia and the tongue were sectioned and examined for labeled cells and fibers, respectively. Analysis of the number and topographic distribution of geniculate cells innervating single taste papillae, shows that: (i) 15 +/- 4 (S.D.) ganglion cells converge to innervate a single fungiform taste bud; (ii) more ganglion cells innervate anterior- (range: 13-35 cells) than posterior-lying buds (range: five to 12 cells), which, in part, may be related to bud volume (microm3); and (iii) ganglion somata innervating a single taste bud are scattered widely within the geniculate ganglion. Analysis of labeled fibers in the tongue demonstrated that two to eight taste buds located within 2 mm of the injected taste bud share collateral innervation with the injected taste bud. Since all buds with labeled fibers were located in close proximity (within a 2-mm radius), widely dispersed geniculate ganglion cells converge to innervate closely spaced fungiform taste buds. Trigeminal ganglion (mandibular division) cells were also labeled in every case and, as with the geniculate ganglion, a dispersed cell body location and collateralization pattern among papillae were observed. This study shows that iontophoresis of tetramethylrhodamine dextran amine, selectively applied to individual peripheral receptor end-organs, effectively locates sensory ganglion cells in two different ganglia that project to these sites. Moreover, the marker demonstrates collateral branches of sensory afferents associated with the labeled fibers and the nearby receptor areas innervated by these collaterals. The labeling of single or clusters of receptor cells, as well as identified sensory afferents, affords future possibilities for combining this technique with immunocytochemistry to establish the relationships of innervation patterns with neurotransmitters and neurotropic substances within identified cells.

Afferent Pathways↗

PubMed1999

The role of the amino-terminal beta-barrel domain of the alpha and beta subunits in the yeast F1-ATPase.

The crystal structure of mitochondrial F1-ATPase indicates that the alpha and beta subunits fold into a structure defined by three domains: the top beta-barrel domain, the middle nucleotide-binding domain, and the C-terminal alpha-helix bundle domain (Abrahams et al., 1994); Bianchet et al., 1998). The beta-barrel domains of the alpha and beta subunits form a crown structure at the top of F1, which was suggested to stabilize it (Abrahams et al. 1994). In this study, the role of the beta-barrel domain in the alpha and beta subunits of the yeast Saccharomyces cerevisiae F1, with regard to its folding and assembly, was investigated. The beta-barrel domains of yeast F1alpha and beta subunits were expressed individually and together in Escherichia coli. When expressed separately, the beta-barrel domain of the beta subunit formed a large aggregate structure, while the domain of the alpha subunit was predominately a monomer or dimer. However, coexpression of the beta-barrel domain of alpha subunit with the beta-barrel domain of beta subunit, greatly reduced the aggregation of the beta subunit domain. Furthermore, the two domains copurified in complexes with the major portion of the complex found in a small molecular weight form. These results indicate that the beta-barrel domain of the alpha and beta subunits interact specifically with each other and that these interactions prevent the aggregation of the beta-barrel domain of the beta subunit. These results mimic in vivo results and suggest that the interactions of the beta-barrel domains may be critical during the folding and assembly of F1.

Amino Acid Sequence↗

PubMed1999

[Problems produced by the use of antitubercular agents in a reference service for HIV/AIDS in Abidjan (Côte d'Ivoire)].

This study reports on the experience using antituberculosis drugs in a HIV/AIDS reference service in Abidjan during a 64 month period. Prevalence of tuberculosis is 1.9% out of a total of 23,957 patients. The annual incidence rate increased slowly from 0.9% in 1990 to 3.5% in 1995. Seropositivity to HIV is 90.8%. Predominant locations of tuberculosis are pulmonary (60.3%), extrapulmonary (19.7%) and multifocal or disseminated (20%). The average period of diagnosis (9.9 days) and average duration of antituberculosis treatment in hospital (11.8 days) are similar whatever the serological status and the location of the infection may be. However, the mortality rate is more important in HIV positive patients (39.7%) than in HIV negative (17.6%) p = 0.01. The decision to treat is taken by infectiologists only in 88% of the cases, by pneumologists only in 2.5%, and both by infectiologists and pneumologists in 9.5%. Side-effects due to antituberculosis drugs were noticed in 19 patients leading to an interruption of the treatment in 10 cases. The authors recommend that health personnel be trained for the management of tuberculosis.

Acquired Immunodeficiency Syndrome↗