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B Cai

Publications and source records attributed to B Cai.

72 records · Page 4Linked to original sources
PubMed1993

Tumor necrosis factor-alpha inhibits endothelium-dependent relaxation.

Tumor necrosis factor-alpha (TNF-alpha) stimulates nitric oxide (NO) in vascular endothelium by induction of the enzyme NO synthase II (NOS II). We examined the effects of TNF-alpha on 1) endothelium-dependent (EDR) and endothelium-independent (EIR) relaxation and 2) contraction of bovine intralobar pulmonary arteries (BPA) and veins (BPV) in vitro. Acetylcholine (ACh), bradykinin (BK), histamine, and A23187 produced EDR of BPA contracted with a 50% effective concentration of U-46619 (15 nM), because relaxation was abolished by endothelium-rubbing and attenuated by L-NG-mono-methylarginine (L-NMMA; 300 microM). TNF-alpha (0.00417, 0.0417, 0.417, and 1.25 micrograms/ml) incubated with BPA for 60 min inhibited EDR of the BPA to ACh, BK, and histamine. The effects of TNF required 30 min for onset. Recovery of EDR occurred 3-4 h after washout of TNF-alpha. Pentoxifylline (1 microM) did not affect ACh-induced EDR but selectively reversed TNF-alpha-mediated inhibition of ACh-induced EDR. TNF-alpha-mediated inhibition of EDR was not reversible by L-NMMA, an inhibitor of NOS I and NOS II, the cyclooxygenase inhibitor ibuprofen, or CV-3908 (1 microM), a platelet-activating factor antagonist. The inhibitory effect of TNF-alpha on EDR was not mediated by nonspecific sensitization of the endothelium to human protein because recombinant human granulocyte colony-stimulating factor (10, 50, and 500 x 10(3) U/ml) did not affect EDR of BPA. The effect of TNF-alpha was specific for release of NO from the endothelium of BPA because TNF-alpha did not affect 1) EDR of BPV to ACh, BK, or ATP; 2) EIR of BPA or BPV to nitroprusside; and 3) contraction of either BPA or BPV to KCl, U-46619, histamine, norepinephrine, or serotonin. Thus TNF-alpha appears to selectively inhibit receptor-mediated EDR and NO release in BPA. TNF-alpha-mediated inhibition of EDR differs from that of L-arginine-based inhibitors and may represent an endogenous physiological mechanism of regulation of NO in the endothelium.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1993

Tumor necrosis factor inhibits stimulated but not basal release of nitric oxide.

Tumor necrosis factor alpha (TNF alpha) increases nitric oxide (NO) synthase in vascular endothelium, but it inhibits endothelium-dependent relaxation (EDR) of vascular smooth muscle. We tested whether TNF alpha inhibits the response to, or release of, NO in bovine pulmonary artery (BPA) using the technique of perfusion-superfusion bioassay and ozone chemiluminescence. Effluent from the perfused BPA with endothelium (donor)-relaxed endothelium-rubbed bovine coronary artery (BCA) (detector). Moreover, effluent from the donor stimulated with acetylcholine (ACh) or bradykinin (BK) (0.001 to 100 nmol) relaxed the detector. Direct application of these agonists to the detector failed to produce relaxation. Basal and agonist-stimulated effluent from the donor treated with L-NG-monomethylarginine (LNMMA) (100 microM) suppressed effluent-mediated relaxation of the detector. ACh and BK released LNMMA-inhibitable nitrite and nitrate from the BPA. Thus, the effluent contained NO. Exposure of the donor to TNF alpha (1.25 micrograms/ml) for 60 min did not affect basal release of NO, but it attenuated bioassayable and chemiluminescence-detectable NO release by ACh and BK. The inhibition of NO release was directly related to the magnitude of inhibition of EDR by ACh and BK. Thus, TNF alpha selectively inhibits receptor-mediated release of NO without affecting basal release of NO. This effect differs from that of L-arginine-based inhibitors of NO and represents a unique physiologic mechanism of regulation of NO in the endothelium.

Acetylcholine↗
PubMed1992

Corroboration of sexual histories among male homosexual couples.

Using data from a study of human immunodeficiency virus transmission among homosexual male partners from Boston, Massachusetts, the authors compared self-reported sexual histories among 155 index-partner pairs during 1985-1988. Overall, high levels of agreement were observed for all reported sexual activities. Agreement on anal sex was very high (Spearman's r = 0.78-0.79, p less than or equal to 0.001; kappa = 0.76-0.88, p less than or equal to 0.001). Level of agreement did vary significantly by a couple's drug and alcohol use; the heavier substance user generally reported fewer sexual encounters than the lighter user. These results have important implications in sexual behavior research and show that among homosexual men, self-reports of sexual behavior may be reasonably valid.

Acquired Immunodeficiency Syndrome↗
PubMed1992

New plasmid vector and host system for genetic engineering in Bacillus sphaericus.

A new plasmid, pNQ116, was constructed in Bacillus sphaericus by cloning a promoter fragment from B. sphaericus Ts-1 into pNQ112. The plasmid (CmrKmr, 5.23 kb) contains a restriction endonuclease polylinker used for cloning foreign genes, and its cat-86 gene is expressed at high levels from the Ts-1 promoter. This plasmid vector has been transformed into B. sphaericus AS 1.270, AS 1.465, AS 1.469, and 2362, at frequencies of 10(2)-10(3) transformants per microgram of DNA, and is maintained stably under nonselective conditions in these host strains. The presence of pNQ116 in B. sphaericus 2362 does ot interfere with the mosquito larvicidal activity of the organism.

Animals↗
PubMed1991

Molecular characterization of Saccharomyces cerevisiae URA6 gene. DNA sequence, mutagenesis analysis, and cell cycle regulation relevant to its suppression mechanism to cdc8 mutation.

Yeast SOC8 DNA fragment was isolated as a wild type dominant suppressor of cdc8 mutation. We have used Bal31 deletion analysis to define the minimal 1 kilobase HpaI-NcoI DNA element required for complementing the cdc8 mutation. The complementing sequence harbored a multicopy plasmid also enhanced by uridine monophosphate kinase in crude extracts. DNA sequence analysis revealed an open reading frame encoding a protein with a molecular weight of 24,949. Since our SOC8 sequence was identical to that of URA6 gene, which encodes uridine monophosphate kinase, we conclude that SOC8 is allelic with URA6, and we use the term URA6 hereafter. Northern blotting experiments showed that the size of mRNA is about 0.9 kibobases. Primer extension experiments showed multiple transcriptional starting sites primarily located at -160 The size and the deduced amino acid composition are consistent with information obtained from purified uridine monophosphate kinase. Thus, both molecular genetic and biochemical evidence supports a notion that the URA6 is SOC8 encoding a yeast uridine monophosphate kinase. Mutagenesis analysis of its putative nucleotide-binding site, altering essential lysine to glutamic acid, resulted in loss of its uridine monophosphate kinase activity. Complementation analysis studies indicated that the mutated ura6 gene abolished its ability to complement ura6 mutant cells; nor could it suppress cdc8 mutation. Unlike CDC8, the mRNA level of the URA6 gene did not fluctuate throughout the cell cycle; presumably, the temporal order of these two enzymatic activities might be different during cell cycle progression. These data may explain an incomplete suppression of cdc8 by URA6, as previously observed. Taken together, the results support our previous speculation that the suppression of the cdc8 mutation mechanisms by URA6 is due to the provision of the trans-acting dTMP kinase activity to complement the cdc8 defect.

Amino Acid Sequence↗
PubMed1991

Apparent enhancement by SCH 23390 of apomorphine-induced locomotor activity in mice.

Effects of the dopamine (DA) D1 antagonist SCH 23390 and the DA D2 antagonist (-)-sulpiride on apomorphine-induced characteristic changes in spontaneous motor activity were investigated in mice using the system we have devised for automatically analyzing animal behaviors in mice. Apomorphine (3 mg/kg, SC) markedly increased parameters of spontaneous motor activity such as locomotor activity and rearing time. Apomorphine-induced increase in locomotor activity had peaks at 5-20 and 30-50 min after administration, and its trough was closely related to the marked increase in rearing time induced by this agonist. Apomorphine-induced locomotor activity accumulated over a 40-min period from 5 to 45 min after apomorphine injection, during which apomorphine-induced increase in rearing time peaked, was significantly increased by intraperitoneal administration of 0.03 and 0.1 but not 0.01 mg/kg SCH 23390. Apomorphine-induced increase in rearing time was dose-dependently depressed by this antagonist. In contrast, (-)-sulpiride (10-40 mg/kg, IP) decreased apomorphine-induced increases in rearing time and locomotor activity rather than enhancing the latter parameter. These data suggest that the apparent enhancement by SCH 23390 of apomorphine-induced locomotor activity is mediated through DA D1 receptors and does not always correlate with depression of apomorphine-induced rearing behavior in mice.

Animals↗
PubMed1991

Desipramine enhances isolation-induced aggressive behavior in mice.

Effects of desipramine on aggressive behavior induced by long-term (6-7 weeks) isolation of mice were examined. Aggressive behavior was measured as duration of biting attack and/or wrestling during a 20-min observation period. Desipramine (5, 10 and 20 mg/kg, IP) and imipramine (10 and 20 mg/kg, IP) dose-dependently increased the duration of aggressive behavior in isolated mice, without inducing aggressive behavior in group-housed animals. Desipramine-induced increase in aggressive behavior was blocked by phentolamine (3 mg/kg, IP) and yohimbine (0.3 mg/kg, IP), but not prazosin (0.5 mg/kg, IP). Clonidine (0.001 mg/kg, IP), an alpha 2 agonist, significantly blocked desipramine-induced enhancement of aggressive behavior in isolated mice without affecting the basal aggression. These data suggest that long-term isolation may induce functional changes in the sensitivity of alpha 2 receptor in the noradrenergic system and that desipramine enhancement of aggressive behavior in isolated mice is modulated by drugs acting onto alpha 2 noradrenergic receptors.

Aggression↗
PubMed1991

Nucleotide sequence of the Rhodobacter capsulatus fruK gene, which encodes fructose-1-phosphate kinase: evidence for a kinase superfamily including both phosphofructokinases of Escherichia coli.

The fruK gene encoding fructose-1-phosphate kinase (FruK), located within the fructose (fru)-catabolic operon of Rhodobacter capsulatus, was sequenced. FruK of R. capsulatus (316 amino acids; molecular weight = 31,232) is the same size as and is homologous to FruK of Escherichia coli, phosphofructokinase B (PfkB) of E. coli, phosphotagatokinase of Staphylococcus aureus, and ribokinase of E. coli. These proteins therefore make up a family of homologous proteins, termed the PfkB family. A phylogenetic tree for this new family was constructed. Sequence comparisons plus chemical inactivation studies suggested the lack of involvement of specific residues in catalysis. Although the Rhodobacter FruK differed markedly from the other enzymes within the PfkB family with respect to amino acid composition, these enzymes exhibited similar predicted secondary structural features. A large internal segment of the Rhodobacter FruK was found to be similar in sequence to the domain bearing the sugar bisphosphate-binding region of the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase of plants and bacteria. Proteins of the PfkB family did not exhibit statistically significant sequence identity with PfkA of E. coli. PfkA, however, is homologous to other prokaryotic and eukaryotic ATP- and PPi-dependent Pfks (the PfkA family). These eukaryotic, ATP-dependent enzymes each consist of a homotetramer (mammalian) or a heterooctamer (yeasts), with each subunit containing an internal duplication of the size of the entire PfkA protein of E. coli. In some of these enzymes, additional domains are present. A phylogenetic tree was constructed for the PfkA family and revealed that the bacterial enzymes closely resemble the N-terminal domains of the eukaryotic enzyme subunits whereas the C-terminal domains have diverged more extensively. The PPi-dependent Pfk of potato is only distantly related to the ATP-dependent enzymes. On the basis of their similar functions, sizes, predicted secondary structures, and sequences, we suggest that the PfkA and PfkB families share a common evolutionary origin.

Amino Acid Sequence↗
PubMed1991

[The effect of lowered pressure on the diastolic ventricular function after antihypertensive treatment].

Thirty hypertensive patients with increased left ventricular (LV) mass and impaired diastolic function received routinely 2 or 3 kinds of captopril, nifedipine and atenolol for a mean period of 98 days. The LV mass index (LVMI) decreased by an average of 21 g/M2, but no significant correlation between blood pressure reduction and decrease in LVMI was found. So there may be some direct effect of these antihypertensive agents on the myocardium in addition to the benefit from blood pressure reduction. Marked reduction in PVA, Ai, A/E and Ai/T-VTi (P less than 0.01) along with elevation in ratio of E/A, Ei/Ai and Ei/T-VTi (P less than 0.01) were also observed by Doppler transmitral filling studies. These results indicated that the impaired LV diastolic function in patients with hypertension can be much improved following reduction of blood pressure and LV mass.

Aged↗
PubMed1991

[A study on components and compound prescription of huangqin decoction].

The results obtained from the pharmacological experiments have preliminarily demonstrated that the compound prescription is better than its individual component drug in the range and potency of pharmacological activities. In the prescription Radix Scutellariae plays a principal role in pharmacological effects. Radix Scutellariae and Radix Paeoniae Alba can potentiate each other. Radix Glycyrrhizae and Fructus Jujubae in the compound prescription also exhibit biological activities to some extent. The relieving effect of the prescription for spasm and pain may result from the synergistic interaction between Radix Paeoniae Alba and Radix Glycyrrhiza, and the heat clearing and diarrhea stopping action is due to the biological activity of Radix Scutellariae.

Animals↗
PubMed1990

[A new system for the measurement and analysis of motor activity in mice: effect of several central stimulants].

To estimate the spontaneous motor activity in mice, a new system with highly stable sensitivity and good reproducibility was made, and the effects of five central stimulants were investigated. The apparatus consists of a doughnut-shaped cage with detectors for measuring spontaneous motor activity; i.e., the number of movements, vertical activity, total distance, etc., for every five min. Methamphetamine (0.5, 1 and 2 mg/kg, s.c.) produced an increase in the number of movement and markedly increased total distance. Cocaine (20, 50 and 75 mg/kg, s.c.) caused a marked increase in movement and total distance. Mice injected with 50 mg/kg of cocaine showed long-lasting locomotion with few stops throughout the observation period. Caffeine (10, 30 and 100 mg/kg, s.c.) produced a long-lasting and moderate excitation. Morphine (5, 10 and 20 mg/kg, s.c.) caused a marked increase in continuous locomotion dose-dependently. Apomorphine produced a transient increase in rearing and locomotion at a dose of 1 mg/kg, s.c.; and it produced long-lasting rearing and moderate locomotor activity at 3 mg/kg. These results suggest that this apparatus is able to detect characteristic changes in spontaneous motor activity produced by central stimulants and may be useful for analyzing drug-induced motor activity in mice in more detail.

Animals↗
PubMed1990

[A preliminary study on the pharmacology of the compound prescription huangqin tang and its component drugs].

Results obtained from the pharmacological experiments demonstrated that the compound prescription Huangqin Tang and its component drugs, roots of Paeonia lactiflora, Scutellaria baicalensis and Glycyrrhiza uralensis, and the fruit of Ziziphus jujuba showed marked anti-inflammatory effect. The compound prescription and its component drugs, except the peony root, possessed significant antispastic effect. Antipyretic effect of Radix Scutellariae, Radix Glycyrrhizae and Huangqin Tang was suggested. Huangqin Tang, Radix Paeoniae alba, and Radix Glycyrrhizae showed marked analgesic effect. In addition, the experiments confirmed that both Huangqin Tang and single Radix Scutellariae have sedative effect.

Animals↗
PubMed1989

[New cloning vectors constructed in Bacillus].

Two new plasmids pNQ216 (4.1kp) and pNQ402 (2.8 kb) were constructed by combining the replication origin of the plasmid pNK289, a cryptic plasmid resides in B. pumilus 289, and the cat-86 gene from plasmid pPL601. These two plasmids can be maintained steadily in both B. subtilis and B. pumilus. The penetrance of these plasmids on LB medium with Cm (20 micrograms/ml) is 30% higher than that of pPL600. Thus both of these plasmids can be used as new cloning vectors in Bacillus.

Bacillus↗
PubMedDate not supplied

Abdominal radical trachelectomy: two new surgical techniques for the conservation of uterine arteries.

The objective of this study was to develop two new techniques for the conservation of uterine arteries in abdominal radical trachelectomy. Abdominal trachelectomy with conservation of uterine arteries was performed in two patients with cervical carcinoma. In the first case, the internal iliac artery was divided at 2.0 cm from the bifurcation of the common iliac artery. The internal iliac artery and uterine artery were skeletonized along their lengths to the lateral cervix. The dissected internal iliac artery was then reanastomosed following the radical trachelectomy. In the second case, the technique was similar to that of the first except that the internal iliac artery was not divided. Intraoperative observation and postoperative color Doppler ultrasound were used to confirm the patency of the uterine arteries. The operative time of the two patients was 390 min. and 350 min, respectively. Doppler flow studies demonstrated that the uterine arteries were patent in both cases. Resistance index of the left and the right uterine artery was 0.58 and 0.61, respectively, in the first case, and 0.60 and 0.63, respectively, in the second case. Reanastomosis of the internal iliac arteries or skeletonization of the internal iliac arteries are both feasible methods to conserve the uterine arteries during abdominal radical trachelectomy.

Adult↗
PubMedDate not supplied

Influence of nifedipine, verapamil and diltiazem on pulmonary vascular resistance and vasoconstrictors in cats.

In the present study, the effects of three classes of L-type calcium channel-blocking agents, nifedipine, verapamil and diltiazem, on the lobar arterial pressure and the vasoconstrictor responses in the pulmonary vascular bed were compared to those of cromakalim, a KATP channel activator, in the anaesthetized cat under controlled pulmonary blood flow and constant left atrial pressure. These drugs were infused intralobarly in doses selected which did not raise left atrial pressure, change cardiac output or alter systemic arterial pressure. Intralobar bolus injections of calcium channel-blocking agents and of the K+ channel activator decreased the lobar arterial pressure in a dose-related manner when pulmonary vasomotor tone was actively elevated by intralobar arterial infusion of U46619. The pulmonary vasodilator response to these agents was accompanied by a dose-related decrease of systemic arterial pressure. In decreasing lobar arterial pressure at elevated pulmonary vasomotor tone, the order of potency was nifedipine > verapamil > diltiazem, whereas in reducing systemic arterial pressure, the order of potency was nifedipine > diltiazem > verapamil. The calcium channel-blocking agents were less active than the reference drug, cromakalim, in both vascular beds. Intralobar arterial infusions of nifedipine, verapamil and diltiazem, at the rates of 0.03 mumol/min, 0.2 mumol/min and 0.1 mumol/min, respectively, caused no changes in cardiac output and in systemic and pulmonary arterial pressure. Infusion of all three calcium-channel-blocking agents blocked the pulmonary vasoconstrictor responses to BAY K 8644 (calcium entry promoter) and U46619 (thromboxane A2 mimic). Nifedipine infusion also reduced the pulmonary vasoconstrictor responses to methoxamine and BHT933 (alpha 1- and alpha 2-adrenoceptor agonists, respectively), whereas verapamil infusion reduced the responses only to methoxamine. Infusion of diltiazem caused no significant decrease of responses to either alpha-adrenoceptor agonist. The results of the present study suggest that the dihydropyridine, nifedipine, is more potent than the non-dihydropyridines, verapamil and diltiazem, in reducing the pulmonary vascular resistance and more effective in inhibiting the vasoconstrictor responses to the alpha-adrenoceptor agonists, to U46619 and to BAY K 8644 in the feline pulmonary circulation at the infusion rates which cause no or little hemodynamic changes.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMedDate not supplied

HIV and hepatitis B infection and risk behavior in young gay and bisexual men.

OBJECTIVES: To estimate the prevalence of and identify risk factors for human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV) infections and unprotected anal intercourse among young homosexual and bisexual men. METHODS: The authors performed a cross-sectional analysis of data from a prospective cohort of 508 young gay and bisexual men ages 18-29. RESULTS: HIV-1 seroprevalence was 2.4%, with five (1.3%) of 390 college students and seven (6.0%) of 117 non-students infected. After adjusting for confounders, HIV-1 infection was associated with having a history of a sexually transmitted disease other than HIV-1 or hepatitis B. The prevalence of hepatitis B markers in unvaccinated men was 12.9%. The presence of hepatitis B markers in unvaccinated men was significantly associated with Asian ethnicity, off-campus residence, and history of a sexually transmitted disease other than HIV-1 or hepatitis B and inversely associated with recent non-intravenous drug use. Eighteen percent of the participants reported having had sex with women during the previous 12 months, and 26.4% reported a history of unprotected anal intercourse during the previous six months. Men who reported unprotected anal intercourse were more likely to have at least one steady partner, to have met their partners in anonymous settings, and to be identified as probably alcohol dependent. CONCLUSIONS: Although the prevalence of HIV-1 infection among young homosexual and bisexual men in Boston was relatively low, the high rates of unprotected anal intercourse suggest a potential for future HIV-1 and hepatitis B transmission. Interventions should focus on young men with histories of sexually transmitted diseases, alcohol abuse, and depression.

Adolescent↗