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Biomedical subjects

L Q Hu

Publications and source records attributed to L Q Hu.

8 recordsLinked to original sources
PubMed2000

[Evaluation of prevalent status of kala-azar in endemic area of Hubei Province].

OBJECTIVE: To identify the diagnosis of 14 cases with "kala-azar" previously reported in Hubei Province since 1989 and to evaluate the present status of the disease. METHODS: Bone marrow smear, immunological test (LDTand IFAT), mouse inoculation, fungi culture, vector (Phlebotomus) and reservoir host (dog) survey. RESULTS: Among the 14 cases, 12 cases were progressive disseminated histoplasmois, one was an imported case and another one was a remnant skin type "kala-azar" case. An immunological survey was conducted during 1997-1999 in 25 townships located in 23 counties of 9 prefectures and cities. A total of 13,890 persons had been examined by LDT, the positive rate was 0.07%, no positive case was found among the persons under 40 years of age. During the survey, 1,756 persons had been examined by IFAT, the results were negative. No Phlebotomus chinensis had been found in the surveyed area. A total of 302 dogs were examined, no sick dog had been found. CONCLUSION: Kala-azar has been eradicated in Hubei Province.

Animals↗
PubMed1999

Apoptosis in rat erectile tissue induced by castration.

AIM: To investigate the effect of androgen on the structure of corpus cavernosum. METHODS: Thirty mature rats were randomized into 3 groups, i.e., simple castration, castration with testosterone (T) supplementation and sham-operated controls. One week after operation, the animals were sacrificed and corpora cavenosa harvested. Apoptosis was detected with the in situ end labeling (ISEL) techniques and DNA fragment analysis. RESULTS: The apoptotic rate was 4.19% in the simple castrated rats, 0. 2% in castrated rats supplemented with T and 0.14% in the controls. Significant difference was found between the simple castrates and other two groups (P < 0.01). When comparing the T-supplementation group with the controls, there was no statistical difference (P > 0.05). CONCLUSION: Castration induced apoptosis in rat corpus cavernosum, that could be prevented by T supplementation. It suggests that androgen plays an important role in maintaining the structure of corpus cavernosum.

Animals↗
PubMed1999

Regeneration of neuronal nitric oxide synthase (nNOS)-containing nerve fibers in rat corpus cavernosum.

AIM: To investigate the effect of cavernous nerve injury on the nNOS-containing nerve fibers in rat corpus cavernosum. METHODS: Thirty-three male SD rats were randomized into 3 groups: 5 rats underwent pelvic exploration without transection of cavernous nerve as the sham-operated controls, the unilateral injury group (14 rats) had the cavernous nerve cut on one side, and the bilateral injury group (14 rats) had the nerves cut on both sides. Corpora cavernosa were harvested at the 3rd week and 6th month after surgery. nNOS-positive nerve fibers were examined with strepavidin peroxidase immunohistochemistry techniques (SP method). RESULTS: After bilateral ablation, the nNOS-positive nerve fibers were significantly decreased at both the 3rd week (17 +/- 4) and the 6th month (16 +/- 4). For the unilateral injury group, the nNOS-positive nerve fibers were similarly decreased on the side of the neurotomy at the 3rd week (18 +/- 6), but by the 6th month, the number increased significantly (61 +/- 9) and approximated the level on the contralateral side (81 +/- 13). CONCLUSION: In rats after unilateral cavernous nerve ablation, nNOS-containing nerve fibers might regenerate 6 months after operation, but regeneration did not occur in animals with bilateral cavernous nerve injury. Results suggest that during pelvic radical surgery, the cavernous nerve should be preserved at least on one side in order to accomplish adequate regeneration.

Animals↗
PubMed1995

The influence of the p-alkyl substituent on the isomerization of o-quinones to p-quinone methides: potential bioactivation mechanism for catechols.

Previously, we have shown that an additional bioactivation pathway for the hepatocarcinogen safrole (1-allyl-3,4-(methylenedioxy)benzene) exists which may contribute to its toxic effects: initial O-dealkylation of the methylenedioxy ring, forming the catechol, hydroxychavicol (HC, 1-allyl-3,4-dihydroxybenzene), 2-electron oxidation to the o-quinone (4-allyl-3,5-cyclohexadien-1,2-dione), and isomerization, forming the more electrophilic p-quinone methide (2-hydroxy-4-allylidene-2,5-cyclohexadien-1-one) [Bolton, J. L., Acay, N. M., & Vukomanovic, V. (1994) Chem. Res. Toxicol. 7, 443-450]. In the present investigation, we explored the effects of changing pi-conjugation at the 4-position on both the rate of isomerization of the initially formed o-quinones to the QMs and the reactivity of the quinoids formed from 4-propylcatechol (1), 2,3-dihydroxy-5,6,7,8-tetrahydronaphthalene (2), and 4-cinnamylcatechol (3). We selectively oxidized the catechols to the corresponding o-quinones or p-quinone methides and trapped these reactive electrophiles with glutathione (GSH). The GSH adducts were fully characterized by UV, NMR, and mass spectrometry. Microsomal incubations with the parent catechols in the presence of glutathione produced only o-quinone glutathione conjugates. However, if the trapping agent (GSH) was added after an initial incubation time, both o-quinone and p-quinone methide GSH conjugates were observed. The results indicate that extended pi-conjugation at the para position enhances the rate of isomerization of the o-quinone to the quinone methide. Thus the half-life of the o-quinones decreased in the following order: the o-quinone of 1 > 2 > HC > 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkylation↗
PubMed1991

[Erythrocytic schizogony of Plasmodium vivax under various conditions of in vitro cultivation].

This study was performed to observe the erythrocytic schizogony of P. vivax under several culture conditions in vitro. Five experimental groups included: 1) static cultivation in candle jar; 2) static cultivation in candle jar with candle relightened; 3) static cultivation under low oxygen tension (5-10%); 4) deep suspension cultivation in test tubes with cotton plunger; 5) deep suspension cultivation in closed test tubes with screw cap. Two different isolates of P. vivax collected from Jingshan County and Zaoyang County were used. Cultivation was initiated with two methods, i.e. direct inoculation from fresh patient blood with malaria parasites and retrieval cultivation from freezing malaria parasite blood. The suspension cultivation in test tube with cotton plunger could not support the schizogony of P. vivax, while other groups could at least complete two schizogony cycles. The best result was obtained with static cultivation under low oxygen tension, the growth of parasites appeared to be more normal. The results showed that cultivation of P. vivax under a low oxygen concentration of 5-10% is preferred and the selection of isolates of P. vivax might be important in in vitro cultivation.

Animals↗
PubMed1989

HPLC separation and characterization of chlorin derivatives with intact ring V from acid degradation products of silkworm excrement crude chlorophyll mixture.

A reversed-phase HPLC system with 88% methanol in 1 M ammonium acetate buffer pH 5.35 as the mobile phase on an ODS column was used to analyse pheophorbides a, a', b, b' and pyropheophorbides a and b. Pyropheophorbides a and b were found in samples obtained from silkworm excrement but not from spinach leaves though the preparation methods used were the same. This difference suggests that chlorophylls undergo metabolism in the body of silkworm to give pyrochlorophyll derivatives.

Animals↗
PubMedDate not supplied

Mechanism of isomerization of 4-propyl-o-quinone to its tautomeric p-quinone methide.

In previous work, we showed that o-quinones (3,5-cyclohexadiene-1,2-diones) can isomerize to p-quinone methides (4-alkyl-2,5-cyclohexadien-1-one) at rates which depend on the type of substituent at the para position [Iverson, S. L., Hu, L. Q., Vukomanovic, V., and Bolton, J. L. (1995) Chem. Res. Toxicol. 8, 537-544]. In the present investigation, we explored the mechanism of this isomerization reaction using 4-propyl-3,5-cyclohexadiene-1,2-dione (PQ) and its benzyl dideuterio analog 4-(1',1'-dideuteriopropyl)-3,5-cyclohexadiene-1, 2-dione (DPQ). The results show that the isomerization reaction is general base-catalyzed, which suggests that amino acids on proteins with basic side chains could catalyze the reaction in vivo. The Bronsted beta value was determined to be 0.23 +/- 0.02, consistent with the transfer of a proton in the rate-determining step. The rate/pH profile generated from the buffer dilution plots showed dependence on hydroxide ion concentration from pH 7.8 to 9, indicative of base catalysis. From pH 6 to 7.8, the reaction was independent of pH, suggesting that other processes compete at low buffer concentration in this pH region. Substitution of the benzyl CH2 group with CD2 dramatically slows the isomerization reaction. The kinetic deuterium isotope effect on quinone methide formation was determined by measuring the amount of quinone methide trapped as GSH conjugates from PQ compared with DPQ. The isotope effect on product formation was 5.5 +/- 0.6, 37 degrees C. These data provide further evidence that formation of these electrophilic quinone methides from o-quinones could be catalyzed by basic residues in vivo and that the reaction could be inhibited by deuterium substitution at the benzyl methylene group.

Alkylation↗