Search PubMed⌕ Search

Biomedical subjects

J Luo

Publications and source records attributed to J Luo.

At least 181 records · Page 10Linked to original sources
PubMed1999

Y-Chromosome evidence for a northward migration of modern humans into Eastern Asia during the last Ice Age.

The timing and nature of the arrival and the subsequent expansion of modern humans into eastern Asia remains controversial. Using Y-chromosome biallelic markers, we investigated the ancient human-migration patterns in eastern Asia. Our data indicate that southern populations in eastern Asia are much more polymorphic than northern populations, which have only a subset of the southern haplotypes. This pattern indicates that the first settlement of modern humans in eastern Asia occurred in mainland Southeast Asia during the last Ice Age, coinciding with the absence of human fossils in eastern Asia, 50,000-100,000 years ago. After the initial peopling, a great northward migration extended into northern China and Siberia.

Africa↗
PubMed1999

Euglycemic hyperinsulinemic clamp to assess posthepatic glucose appearance after carbohydrate loading. 2. Evaluation of corn and mung bean starches in healthy men.

BACKGROUND: The rate of absorption of glucose from carbohydrates is important in several aspects of health. We recently validated a noninvasive technique in pigs, euglycemic hyperinsulinemic clamp plus oral carbohydrate loading (OC-Clamp), to quantify the rate of net posthepatic appearance of glucose after ingestion of carbohydrates. OBJECTIVE: The OC-Clamp procedure was performed in 8 healthy men to compare the net posthepatic appearance of glucose after ingestion of 1 of 3 carbohydrates. DESIGN: Human volunteers underwent the OC-Clamp procedure at an insulin infusion rate of 1.5 mU x kg(-1) x min(-1) (n = 5). The oral carbohydrate load (1 g/kg) consisted of glucose, cornstarch, or mung bean starch. During the OC-Clamp procedure, the glucose infusion rate decreased during absorption to maintain plasma glucose steady state and the decrease reflected the net posthepatic appearance of glucose. In addition, carbohydrates were loaded without insulin infusion (n = 6) and glycemic indexes were calculated (with glucose as the reference). RESULTS: The mean (+/-SEM) glycemic index of cornstarch was higher (95 +/- 18) than that of mung bean starch (51 +/- 13). In the OC-Clamp experiments, the posthepatic appearance of glucose and cornstarch did not differ significantly and represented 79.4 +/- 5.0% and 72.6 +/- 4.0%, respectively, of the load after complete absorption (within 3 h). In contrast, the net posthepatic appearance of glucose from mung bean starch was significantly lower (35.6 +/- 4.6% of the load, P < 0.001) than that from glucose and cornstarch, even 4.5 h postprandially. CONCLUSIONS: The OC-Clamp technique allows a continuous assessment of net posthepatic appearance of glucose after ingestion of carbohydrates and significant discrimination between corn and mung bean starches.

Analysis of Variance↗
PubMed1999

Identification and characterization of diadenosine 5',5"'-P1,P2 -diphosphate and diadenosine 5',5"'-P1,P3-triphosphate in human myocardial tissue.

We examined whether human cardiac tissue contains diadenosine polyphosphates and investigated their physiological role. Extracts from human cardiac tissue from transplant recipients were fractionated by size exclusion-, affinity-, anion exchange- and reversed-phase chromatography. MALDI-MS analysis of two absorbing fractions revealed molecular masses of 676.2 Da and 756.0 Da. The UV spectra of both fractions were identical to that of adenosine. Postsource decay MALDI mass spectrometry indicated that the molecules with a mass of 676.2 Da and 757.0 Da contained AMP and ATP, respectively. As shown by enzymatic cleavage, both molecules consist of two adenosines interconnected by either two or three phosphates in 5'-positions of the riboses. Two substances can be identified as 5',5"'-P1,P2-diphosphate (Ap2A) and 5',5"'-P1, P3-triphosphate (Ap3A). Ap2A and Ap3A, together with ATP and ADP, are stored in myocardial-specific granules in biologically active concentrations. In the isolated perfused rat heart, Ap2A and Ap3A caused dose-dependent coronary vasodilations. In myocardial preparations, Ap2A and Ap3A attenuated the effect of isoproterenol, exerting a negative inotropic effect. The calcium current of guinea pig ventricular myocytes, stimulated by isoproterenol, was also attenuated by Ap2A and Ap3A. The presence of Ap2A and Ap3A in cardiac-specific granules and the actions of these substances on the myocardium and coronary vessels indicate a role for these substances as endogenous modulators of myocardial functions and coronary perfusion.

Animals↗
PubMed1999

Study on genital tract Chlamydia trachomatis and gonococcal infection in Han and minority (Naxi and Dai) women in China's two provinces.

OBJECTIVES: To estimate the prevalence of lower female genital tract chlamydial (GTC) and gonococcal infection in 3 different ethnic groups in China, and to analyze the risk factors influencing these infections. METHODS: A cross-sectional survey + physical and laboratory examinations. 1,800 married women aged 18-35 Han (600, from Dujiangyan city, Sichuan), Naxi (600, from Yanyuan county, Sichuan), and Dai (600, from Jinghong Prefecture, Yunnan) were investigated between March 1996 to March 1997. Information was obtained about their personal history, socioeconomic status, medical history, STDs, sexual history, contraceptive history, results of both examinations. Tabulation, t-test, Chi-square test, multiple-logistic models were used to analyze the data. RESULTS: 3.2% of Han, 12.8% of Naxi and 4.5% of Dai women tested positive for gonococci; and 9.1% of Han, 16.7% of Naxi and 27.5% of Dai women tested positive for GTC infection. The differences of GTC and gonococcal infections between Han and Naxi, and Han and Dai women were significant. CONCLUSIONS: STDs are common in China today; both GTC and gonoccocal infections are related to non-use of condom, having sexual partners other than husband, number of abortions, and low education; and condom has a function in prevention of STDs.

Adolescent↗
PubMed1999

In vitro transcriptional studies of the bkd operon of Pseudomonas putida: L-branched-chain amino acids and D-leucine are the inducers.

BkdR is the transcriptional activator of the bkd operon, which encodes the four proteins of the branched-chain keto acid dehydrogenase multienzyme complex of Pseudomonas putida. In this study, hydroxyl radical footprinting revealed that BkdR bound to only one face of DNA over the same region identified in DNase I protection assays. Deletions of even a few bases in the 5' region of the BkdR-binding site greatly reduced transcription, confirming that the entire protected region is necessary for transcription. In vitro transcription of the bkd operon was obtained by using a vector containing the bkdR-bkdA1 intergenic region plus the putative rho-independent terminator of the bkd operon. Substrate DNA, BkdR, and any of the L-branched-chain amino acids or D-leucine was required for transcription. Branched-chain keto acids, D-valine, and D-isoleucine did not promote transcription. Therefore, the L-branched-chain amino acids and D-leucine are the inducers of the bkd operon. The concentration of L-valine required for half-maximal transcription was 2.8 mM, which is similar to that needed to cause half-maximal proteolysis due to a conformational change in BkdR. A model for transcriptional activation of the bkd operon by BkdR during enzyme induction which incorporates these results is presented.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1999

Novel, non-radioactive, simple and multiplex PCR-cRFLP methods for genotyping human SP-A and SP-D marker alleles.

We have previously identified an allele of the human SP-A2 gene that occurs with greater frequency in an RDS population [12]. Because of the importance of SP-A in normal lung function and its newly emerging role in innate host defense and regulation of inflammatory processes, we wish to better characterize genotypes of both SP-A1 and SP-A2 genes. It has been determined that SP-D shares similar roles in immune response. Therefore, in this report we 1) describe a novel, non radioactive PCR based-cRFLP method for genotyping both SP-A and SP-D; 2) describe two previously unpublished biallelic polymorphisms within the SP-D gene; 3) present the partial sequence of one new SP-A1 allele (6A14) and describe other new SP-A1 and SP-A2 alleles; and 4) describe additional methodologies for SP-A genotype assessment. The ability to more accurately and efficiently genotype samples from individuals with various pulmonary diseases will facilitate population and family based association studies. Genetic polymorphisms may be identified that partially explain individual disease susceptibility and/or treatment effectiveness.

Alleles↗
PubMed1999

Chronic ventromedial hypothalamic infusion of norepinephrine and serotonin promotes insulin resistance and glucose intolerance.

The ventromedial hypothalamus (VMH) is involved in the regulation of peripheral metabolism. We and others have shown that activities, or extracellular metabolites of norepinephrine (NE) and serotonin (5-HT) are elevated in the VMH of both genetically and seasonally insulin-resistant and glucose-intolerant animals. This study examined whether chronic increases in VMH NE and 5-HT concentration of normal animals might lead to insulin-resistant and glucose-intolerant conditions in hamsters. Euinsulinemic, glucose-tolerant hamsters were infused continuously for 5 weeks into the right VMH with either vehicle, NE (5 or 25 nmol/h), 5-HT (2.5 nmol/h), or NE (5 or 25 nmol/h) plus 5-HT (2.5 nmol/h) through osmotic minipumps. Compared to vehicle, NE (25 nmol/h) significantly increased the glucose total area under the curve (TAUC) by 32% during glucose tolerance tests (GTT) conducted after 5 weeks' infusion. 5-HT alone significantly increased the GTT insulin TAUC (131%) and basal plasma insulin level (116%) but not glucose TAUC. NE (5 nmol/h) plus 5-HT infusion significantly increased insulin TAUC (129%) and basal plasma insulin (120%), whereas NE (25 nmol/h) plus 5-HT infusion significantly increased both the GTT glucose and insulin TAUC (43 and 113%, respectively), as well as basal plasma insulin level (158%), relative to vehicle infusion. Our findings demonstrate for the first time the differential and, more importantly, interactive effects of increased VMH NE and 5-HT in producing hyperinsulinemia, insulin resistance and glucose intolerance.

Animals↗
PubMed1999

Identification of diadenosine hexaphosphate in human erythrocytes.

Diadenosine polyphosphates have been identified as important regulators of vascular tone and blood pressure. In reference to the background of the well-known vasoconstriction induced by hemolysate, we questioned whether this action may be due in part to the presence of diadenosine polyphosphates in human erythrocytes. Therefore, erythrocytes were separated from other blood cells and deproteinated. To concentrate and purify nucleotides, the extract was chromatographed by anion exchange, affinity, and reversed-phase columns. In one of the purified fractions, diadenosine hexaphosphate (diadenosine 5', 5'-P(1), P(6) hexaphosphate [AP(6)A]) was identified by matrix-assisted laser desorption/ionization mass spectrometry, ultraviolet spectroscopy, and enzymatic analysis. Hemolysate of erythrocytes injected into the isolated perfused rat kidney induced a dose-dependent vasoconstriction, which was partially inhibited by P(2)-purinoceptor antagonist. The data document the existence of AP(6)A in erythrocytes. AP(6)A may be involved in the pathogenesis of vasospasm induced by free hemoglobin.

Animals↗
PubMed1999

Isolation and antihyperglycemic activity of bakuchiol from Otholobium pubescens (Fabaceae), a Peruvian medicinal plant used for the treatment of diabetes.

The known compound bakuchiol (1) was isolated from an extract of Otholobium pubescens (Fabaceae) by bioassay-guided fractionation using the db/db mouse model for type 2 diabetes. Oral administration of 1 reduced blood glucose levels in a dose-dependent fashion in db/db mice and did not display a hypoglycemic effect when tested in lean mice at 250 mg/kg q.d. Compound 1 was further evaluated in a new rodent model for type 2 diabetes, the fat-fed, streptozotocin (STZ)-treated rat. In this model, an oral dose of 1 at 150 mg/kg q.d. significantly lowered plasma glucose and triglyceride levels.

Analysis of Variance↗
PubMed1999

Ethanol induces cell death and cell cycle delay in cultures of pheochromocytoma PC12 cells.

Animal models have clearly established that ethanol exposure can deplete neurons in the developing nervous system. However, the mechanism by which ethanol reduces cell number is unclear. In our study, cultures of pheochromocytoma cells, a neuronal-like cell line, were maintained in media, which supported cell proliferation. Although cell numbers continued to increase in the presence of ethanol, this increase was partially inhibited by ethanol exposure. This inhibitory effect was concentration and duration dependent. Cell proliferation was still partially inhibited after removal of ethanol, but this inhibition was temporary and disappeared after a 24-hr recovery period in ethanol-free conditions. Further study indicated that ethanol partially inhibited the increase in cell numbers by two mechanisms: (1) studies with vital stains indicated that ethanol induced cell death; (2) experiments using synchronized pheochromocytoma cell cultures showed that ethanol can induce cell cycle delay, thereby lengthening the doubling time of the cells. Analysis by flow cytometry indicated that with ethanol exposure, the cells accumulated in the G1 phase of the cell cycle. Our results suggest that in the developing nervous system, ethanol may limit the numbers of proliferating, neuronal precursor cells by two simultaneous mechanisms, cell death and cell cycle delay.

Animals↗
PubMed1999

Coronal approach for the replacement of the condylar head in bilateral temporomandibular joint ankylosis: report of three cases.

Limitation of mouth opening has long been the chief complaint for patients who suffer from temporomandibular joint (TMJ) ankylosis. For surgical treatment of this disease, several ways have been employed for access to the condylar fossa, including the preauricular, postauricular, perimeatal, endaural and Risdon approaches. In this article, we report three patients with bilateral TMJ ankylosis who underwent replacement of both condylar heads using the bicoronal approach. The advantages demonstrated with this surgical technique are ease of access to the condylar head, ideal surgical exposure field, utility of temporalis muscle and fascia and minimal risk of facial paralysis.

Adult↗
PubMed1999

[Linkage analysis of chromosome 5 and asthma in a Chinese population].

OBJECTIVE: To investigate the linkage between asthma and 5q31-33 in a Chinese population. METHODS: The linkage between microsatellite markers in 5q and asthma and allergy was tested by lod score analysis. RESULTS: The linkage between asthma and 5q31-33 was not confirmed. CONCLUSION: The genes at 5q31-33 are not likely to contribute to inheritance of asthma in this Chinese population.

Asthma↗
PubMed1999

[Relationship between histopathologic observation of cervical condyloma and human papillomavirus infection].

OBJECTIVE: To study the relationship between histopathologic changes of cervical condyloma and different subtypes human papillomavirus (HPV) infection. METHODS: 158 women with abnormal Pap smears diagnosed by computer assisted cytologic technique (CCT) including 71 cases with atypical squamous cells of undetermined significance (ASCUS), 65 cases with low-grade squamous intraepithelial lesions (LSIL), 17 cases with high-grade squamous intraepithelial lesions (HSIL) and 5 cases with squamous cancers, underwent directed biopsies under colposcopy and were simultaneously detected for HPV6/11, HPV16/18 DNA by polymerase chain reaction (PCR). Koilocytotisis in 73 cases with pathologically proven cervical condyloma were grouped into type I and II according to its atypical degree of nuclei. RESULTS: HPV16/18 infection rate among condylomas cases was 86.0%, which was significantly higher than that of type I (16.7%) (P < 0.01). In LSIL with type II koilocytotisis, HPV16/18 infection rate and abnormal mitotic figures (AMFs) occurrence were 85.7%, significantly higher than those in type I koilocytotisis or cervical intraepithelial neoplasia I. CONCLUSIONS: Type II koilocytotisis was correlated with HPV16/18 infection. LSIL with type II koilocytotisises, distinct atypical nuclei, also associated with high HPV16/18 rate and AMFs, therefore treatment and follow-up should be more aggressive.

Adult↗
PubMed1999

[The effects of IL-1 on synthesis of collagen in scar-derived fibroblasts].

OBJECTIVE: To investigate modulation of cytokines on biological activities of scar-derived fibroblasts. METHODS: This study focused on the effects of interleukin-1 (IL-1) on collagen biosynthesis, nucleic acid, and cell organs of fibroblasts. RESULTS: The results showed the IL-1 could reduce not only the collagen synthesis of fibroblasts, but also quantity of nucleic acid. CONCLUSION: The authors confirm that IL-1 is a cytokine with down-regulation effect on scar formation, and suggest that IL-1 can play an important role in prevention and treatment of scar.

Adolescent↗
PubMed1999

[Internal drainage combined with intraoperative radiotherapy and chemotherapy for pancreatic head carcinoma].

OBJECTIVE: To improve the palliative effect on intermediate or advanced pancreatic head carcinoma. METHODS: 26 patients with intermediate or advanced pancreatic head carcinoma underwent cholecystojejunostomy combined with intraoperative radiotherapy with an electron beam on carcinoma from May 1996 to May 1998. The catheter of multifunctional implantable drug delivery system was inserted via gastroduodenal artery for postoperative perfusion chemotherapy. RESULTS: Follow-up for 3 - 27 months showed that all carcinomas shrunk with pain released in different degrees after a course of treatment. The 6-month, 12-month and 24-month survival rates were 100%, 93.9% and 20% respectively. Five patients survived on the average for 17.8 months. CONCLUSIONS: This protocol is effective to prolong the life of the patients with intermediate or advanced pancreatic head carcinoma.

Adult↗
PubMed1999

[A pathological study on the correlation of HPV infection with precancerous cervical lesions].

OBJECTIVE: To study the correlation of cervical condyloma and cancerous lesions with HPV infection. METHODS: Cervical biopsies and histopathological examinations were performed on 179 cases which had abnormal cervical cytological smears. PCR was used to study the HPV-DNA of 128 cases and in situ hybridization (ISH) was used to study 10 cases. RESULTS: 1. Morphologic observations. Most cervical condyloma cases were of the morphologically flat type (97.7%). Two koilocyte types were observed, the classical, or so called diagnostic koilocyte type (39.7%) and the atypical type (60.3%). Cervical condyloma often occurred together with cervical intraepithelial neoplasia (CIN, 42.5%). 2. PCR HPV DNA subtype analysis. Of the 58 cervical flat condyloma, 5 were PHV6/11 positive (8.6%) and 28 were HPV16/18 positive (48.3%). 86.1% of those with atypical koilocyte and 9.1% of those with diagnostic koilocyte had HPV16/18 infection. 66.7% of the lesions in which condyloma coexisted with CIN(2-3) had HPV16/18 infection. CONCLUSIONS: Most cervical condyloma lesions were of the flat type. The appearance of atypical koilocyte is correlated to HPV16/18 infection, which in turn is correlated to the degree of CIN malignancy.

Adult↗
PubMed1999

[Urotoxic effect to intestinal bacteria in patients with chronic renal failure].

UNLABELLED: To analyse the differences of intestinal bacterial quality and quantity, the feces taken from chronic renal failure(CRF) and healthy subject were cultured aerobicly. Then the isolated E. coli from CRF patients and healthy subjects was inoculated respectively into cultural medium with CRF serum and incubated whose concentration of UN, Cr and UA in medium before and after incubation was measured to observe the bacteria degrade of the above-mentioned urotoxin. RESULT: The intestinal E. coli can apparently degrade UN, Cr and UA in CRF patients which suggests that urotoxin may induce E. coli variation.

Adolescent↗