Search PubMed⌕ Search

Biomedical subjects

H Cheng

Publications and source records attributed to H Cheng.

At least 55 records · Page 3Linked to original sources
PubMed2001

Differential expression of decorin and biglycan genes during mouse tooth development.

Small leucine-rich proteoglycans (SLRPs) have a number of biological functions and some of them are thought to regulate collagen mineralizaton in bone and tooth. We have previously identified and immunolocalized two members of the SLRPs family, decorin and biglycan, in bovine tooth/periodontium. To investigate their potential roles in tooth development, we examined the mRNA expression patterns of decorin, biglycan and type I collagen in newborn (day 19) mice tooth germs by in situ hybridization. At this developmental stage, the first maxillary and mandibular molars include stages before and after secretion of the predentin matrix, respectively. The expression of decorin mRNA coincided with that of type I collagen mRNA and was mostly observed in secretory odontoblasts, while the biglycan mRNA was expressed throughout the tooth germ, including pre-secretory odontoblasts/ameloblasts, dental papilla and stellate reticulum. However, its signal in secretory odontoblasts was not as evident as that of decorin. In mandibular incisors, where a significant amount of predentin matrix and a small amount of enamel matrix were already secreted, a similar differential expression pattern was observed. In secretory ameloblasts the biglycan mRNA expression was apparent, while that of decorin was not. These differential expression patterns suggest the distinct roles of biglycan and decorin in the process of tooth development.

Animals↗
PubMed2001

Structural and kinetic characterization of early folding events in beta-lactoglobulin.

We have defined the structural and dynamic properties of an early folding intermediate of beta-lactoglobulin known to contain non-native alpha-helical structure. The folding of beta-lactoglobulin was monitored over the 100 micros--10 s time range using ultrarapid mixing techniques in conjunction with fluorescence detection and hydrogen exchange labeling probed by heteronuclear NMR. An initial increase in Trp fluorescence with a time constant of 140 micros is attributed to formation of a partially helical compact state. Within 2 ms of refolding, well protected amide protons indicative of stable hydrogen bonded structure were found only in a domain comprising beta-strands F, G and H, and the main alpha-helix, which was thus identified as the folding core of beta-lactoglobulin. At the same time, weak protection (up to approximately 10-fold) of amide protons in a segment spanning residues 12--21 is consistent with formation of marginally stable non-native alpha-helices near the N-terminus. Our results indicate that efficient folding, despite some local non-native structural preferences, is insured by the rapid formation of a native-like alpha/beta core domain.

Animals↗
PubMed2001

Neurourologic findings in patients with traumatic thoracolumbar vertebra junction lesions.

OBJECTIVE: To investigate neurourologic involvement in injuries to the thoracolumbar vertebra junction with magnetic resonance imaging (MRI) and electrophysiologic and urodynamic measurements and to characterize the neurogenic mechanisms of voiding dysfunctions. DESIGN: Baseline comparisons among 3 anatomic groups before neural repair. SETTING: Tertiary care center. PATIENTS: Thirty-five T11 to L2 spinal cord injury patients consecutively admitted to a rehabilitation unit. Eight patients (Group 1) had above-conus lesions without denervation and polyphasic waves revealed in the anal sphincter electromyography; 13 patients (Group 2) had conal and/or above-conus lesions and anal sphincter electromyographic abnormalities; and 14 patients (Group 3) had below-conus lesions and anal sphincter electromyographic abnormalities. MAIN OUTCOME MEASURES: Comparison of features identified on pudendal nerve terminal motor latency, urethral pressure profiles, and multichannel voiding pressure-flow study. RESULTS: The pudendal nerve terminal motor latency in Group 3, showing a significantly higher abnormal ratio (100%; p =.011, Fisher's exact test), indicated that cauda equina lesions might be the cause. Urodynamic data from Group 3 showed a significant decrease in maximal urethral closure pressure (48 +/- 17cm H2O, p =.0022, analysis of variance [ANOVA], repeated measure) and an increase in bladder capacity (429 +/- 194mL, p =.037, ANOVA, repeated measure). There were no significant changes in the other groups. CONCLUSION: Neurourologic abnormalities are less predictable with injuries to thoracolumbar junction, except in patients with cauda equina lesions.

Adult↗
PubMed2001

Quantitative and morphological characteristics of the human corneal endothelium in relation to age, gender, and ethnicity in cataract populations of South Asia.

PURPOSE: To describe the differences of corneal endothelial cell densities, cell size variability and cell hexagonality in cataract populations of south Asia between sexes and ethnic groups. METHODS: 1,235 eyes of 1,235 male and female patients 40-75 years of age with senile cataract were examined with non contact specular microscopy with semi-automated analysis technique. The cell data of the study population was analyzed in relation to age, sex, and ethnic groups. Mean arithmetic differences and the coefficient of variation of repeated observations were calculated to estimate precision of the technique utilized. The main outcome measures were corneal endothelial cell density, cell size variability and cell hexagonality. RESULTS: The mean corneal endothelial cell density was 2,720 cells/mm2, mean cell size variability was 37.8% and percent cell hexagonality 40%. We found statistical significant difference between the three ethnic populations in all the corneal endothelial cell measurements (p<0.0001). Females had a 2.9% greater cell density than males (p = 0.0001). There was no significant difference in mean cell density according to age. Variability of cell size, however, increased with age (p<0.001). These findings were consistent across the three ethnic groups. CONCLUSIONS: In a total sample of 1,235 eyes distributed evenly in three cataract patient populations of south Asia, we found statistically significant differences of corneal endothelial cell densities of cell size variability and cell hexagonality between sexes and ethnic groups.

Adult↗
PubMed2001

Relative accuracy of nucleic acid amplification tests and culture in detecting Chlamydia in asymptomatic men.

Published estimates of the sensitivity and specificity of PCR and ligase chain reaction (LCR) for detecting Chlamydia trachomatis are potentially biased because of study design limitations (confirmation of test results was limited to subjects who were PCR or LCR positive but culture negative). Relative measures of test accuracy are less prone to bias in incomplete study designs. We estimated the relative sensitivity (RSN) and relative false-positive rate (RFP) for PCR and LCR versus cell culture among 1,138 asymptomatic men and evaluated the potential bias of RSN and RFP estimates. PCR and LCR testing in urine were compared to culture of urethral specimens. Discordant results (PCR or LCR positive, but culture negative) were confirmed by using a sequence including the other DNA amplification test, direct fluorescent antibody testing, and a DNA amplification test to detect chlamydial major outer membrane protein. The RSN estimates for PCR and LCR were 1.45 (95% confidence interval [CI] = 1.3 to 1.7) and 1.49 (95% CI = 1.3 to 1.7), respectively, indicating that both methods are more sensitive than culture. Very few false-positive results were found, indicating that the specificity levels of PCR, LCR, and culture are high. The potential bias in RSN and RFP estimates were <5 and <20%, respectively. The estimation of bias is based on the most likely and probably conservative parameter settings. If the sensitivity of culture is between 60 and 65%, then the true sensitivity of PCR and LCR is between 90 and 97%. Our findings indicate that PCR and LCR are significantly more sensitive than culture, while the three tests have similar specificities.

Bias↗
PubMed2001

Molecular cloning and characterization of a novel human gene (HSPBAP1) from human fetal brain.

Rat PASS1 is a novel protein binding specifically to hsp27 and thus plays a role in regulating stress response in the living cell. Here we report on a human homologue of PASS1, encoded by the gene HSPBAP1. The gene was cloned and identified during a large-scale sequencing analysis of a human fetal brain cDNA library. The human protein shared 80% amino acid identity with rat PASS1. According to bioinformatics analysis, the HSPBAP1 gene is located on chromosome 3q21. RT-PCR analysis indicated that HSPBAP1 was abundant in thymus and pancreas but had a ubiquitously low expression pattern in other human adult tissues except for brain where it was absent.

Amino Acid Sequence↗
PubMed2001

Adenoviral vector-mediated gene transfer for human gene therapy.

Human gene therapy promises to change the practice of medicine by treating the causes of disease rather than the symptoms. Since the first clinical trial made its debut ten years ago, there are over 400 approved protocols in the United States alone, most of which have failed to show convincing data of clinical efficacy. This setback is largely due to the lack of efficient and adequate gene transfer vehicles. With the recent progress in elucidating the molecular mechanisms of human diseases and the imminent arrival of the post genomic era, there are increasing numbers of therapeutic genes or targets that are available for gene therapy. Therefore, the urgency and need for efficacious gene therapies are greater than ever. Clearly, the current fundamental obstacle is to develop delivery vectors that exhibit high efficacy and specificity of gene transfer. Recombinant adenoviruses have provided a versatile system for gene expression studies and therapeutic applications. Of late, there has been a remarkable increase in adenoviral vector-based clinical trials. Recent endeavors in the development of recombinant adenoviral vectors have focused on modification of virus tropism, accommodation of larger genes, increase in stability and control of transgene expression, and down-modulation of host immune responses. These modifications and continued improvements in adenoviral vectors will provide a great opportunity for human gene therapy to live up to its enormous potential in the second decade.

Adenoviridae↗
PubMed2001

Electroacupuncture-induced neural activation detected by use of manganese-enhanced functional magnetic resonance imaging in rabbits.

OBJECTIVE: To investigate the effects of acupuncture on neural activity detected by use of manganese-enhanced functional magnetic resonance imaging (fMRI) and elucidate the relationship between somatic acupoint stimulation and brain activation. ANIMALS: 40 New Zealand White rabbits. PROCEDURE: Manganese-enhanced fMRI was performed in anesthetized rabbits manipulated with electroacupuncture (EA) on Zusanli (ST-36) and Yanglingquan (GB-34) acupoints. Image acquisition was performed on a 1.5T superconductive clinical scanner with a circular polarized extremity coil. T1-weighted images were acquired sequentially as follows: baseline, after mannitol injection, after manganese infusion, and 5 and 20 minutes after initiation of EA. RESULTS: Changes in focal neural activity were detected by use of manganese-enhanced fMRI. Stimulation on Zusanli (ST-36) for 5 minutes resulted in activation of the hippocampus, whereas stimulation on Yanglingquan (GB-34) resulted in activation of the hypothalamus, insula, and motor cortex. Activation became less specific after 20 minutes of EA. Furthermore, stimulation on ipsilateral acupoints led to bilateral brain activation. CONCLUSIONS AND CLINICAL RELEVANCE: Each acupoint has a corresponding cerebral linkage, and stimulation on these points resulted in time-dependent neural activation. Understanding the linkage between peripheral acupoint stimulation and central neural pathways may provide a useful guide for clinical applications of acupuncture.

Animals↗
PubMed2001

A metastatic pituitary carcinoid tumor successfully treated with gamma knife radiosurgery.

Intracranial metastasis occurs in a certain number of patients with carcinoid tumor. However, carcinoid tumor with metastasis to the pituitary gland is extremely rare. Up to the present, no effective treatment for either a metastatic intracranial carcinoid tumor or a metastatic pituitary lesion of any origin has been documented. We have treated a case of metastatic carcinoid tumor of the pituitary gland with transsphenoidal tumor resection followed by gamma knife radiosurgery. A 59-year-old man presented with headache and left oculomotor palsy. He was treated at the same hospital for bronchial atypical carcinoid tumor one and a half years ago. Magnetic resonance image of the brain showed a pituitary tumor. There were no signs of recurrent or metastatic lesion elsewhere despite thorough investigation. Transsphenoidal approach for removal of tumor was done and the pathology turned out to be a metastatic carcinoid tumor. Subsequent gamma knife radiosurgery was given for residual tumor. The oculomotor palsy improved after radiosurgery. No neurological deficit occurred. Follow-up CT scan of the brain showed complete resolution of the tumor. We concluded that gamma knife radiosurgery could be used to treat a metastatic intracranial carcinoid tumor. It can also be used to treat a metastatic lesion of the pituitary gland without causing neurological deficit.

Carcinoid Tumor↗
PubMed2001

[cDNA cloning and sequence analysis of human lactoferrin].

Human lactoferrin (hLF) cDNA was amplified by RT-PCR from normal human mammary tissue obtained from Daxing County of Beijing City of China, and then subcloned into pGEM-T vector. hLF cDNA sequence was determined, which consists of 2136 bp. Comparison with five other hLF cDNA sequences registered in GenBank shows 99% homology in DNA sequence. However, there are two base substitutions (nucleotide 1740 G-->C, nucleotide 1756 T-->C), one of which subsequently leads to an amino acid change (residue 580 Glu-->Asp).

Base Sequence↗
PubMed2001

[Prevalent forecast of kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae].

The prevalent analysis of kiwifruit bacterial canker for several years showed that the effective ecological factors of severe degree were the precipitation (x1) in the second and last ten-days of March, and the average temperature (x2) of January. The model was y = 2.1359 + 0.0107x1 - 0.6061x2. The main factor of the prevalence was the relative variation of ten-days average temperature and precipitation in Winter and in early Spring, and the regression equation was y = -8.127 + 22.739x - 13.254x2. The forecast effect of the equation was obviously significant after testing.

Actinidia↗
PubMed2001

[Ecological factors affecting prevalence of kiwifruit bacterial canker and bacteriostatic action of bacteriocides on Pseudomonas syringae pv. actinidae].

According to the systematic study for 5 years, this paper dealt with the ecological factors affecting prevalence of kiwifruit bacterial canker. The disease was more serious in the orchards with above 750 m in elevation, and more serious at mountain slope facing south than facing north. Incidence differed significantly among cultivars, with easy disease infection for Jinfeng, and strong disease resistance for Jinkui. The older the trees, the more the diseased plants. The one year old twigs had highest death twig incidence of diseased twigs and death twig incidence than other twigs. Among 6 tested bacteriocides, Jiaruinong and streptomycin showed best bacteriostatic effect.

Actinidia↗
PubMed2001

Effects of acute or prolonged exposure to leptin on hepatic glucose oxidation.

OBJECTIVE: To observe the short-term and long-term effects of leptin on hepatic glucose oxidation and glucokinase gene expression. METHODS: Rat hepatic cell line BRL was incubated with leptin of different doses (range from 10 ng/ml-200 ng/ml) for 1 h or 24 h. Glucose oxidation was determined by liquid scintillation counting. Glucokinase gene expression (corrected by beta-actin) was determined by reverse transcription semi-quantitative polymerase chain reaction. RESULTS: Treatment with leptin 10 ng/ml for 1 h had no significant effects on glucose oxidation in hepatic cells. However, at the doses ranging from 50 ng/ml to 200 ng/ml, leptin significantly inhibited glucose oxidation. These effects disappeared when the hepatic cells were exposed to leptin for 24 h. Glucokinase mRNA expression was reduced significantly after both 1 h and 24 h exposure to leptin (100 ng/ml) as compared to that of the control group. CONCLUSION: A low dose of leptin has no significant effect on glucose oxidation in hepatic cells. A relatively high dose of leptin has an acute inhibitory effect on the glucose oxidation in hepatic cells. This effect may likely involve the inhibition of glucokinase gene expression. The inhibitory effect on glucose oxidation is transient and disappears with prolonged exposure time.

Animals↗
PubMed2001

Relationship of large multifunctional proteasome 7 gene polymorphism with susceptibility to type 1 diabetes mellitus and DR3 gene.

OBJECTIVE: To study the relationship of the large multifunctional proteasome 7 (LMP7) gene polymorphism with susceptibility to type 1 diabetes mellitus (DM-1) and the DR3 gene in south Chinese Han population. METHODS: LMP7 genotypes and the DR3 gene were identified in 71 DM-1 patients and 86 healthy persons (as controls) by polymerase chain reaction-restriction fragment length polymorphism. DM-1 patients and controls were divided into DR3-positive and DR3-negative subjects. The frequencies of LMP7 genotypes and alleles were compared between DM-1 patients and controls respectively in the random subjects and in the DR3-matched subjects. Furthermore, DM-1 patients were divided into 3 groups according to the age of diabetic onset: group A < or = 14 years, group B 15-30 years, group C > or = 31 years. RESULTS: In the random subjects, the frequency of LMP7-B/B was lower (39% vs 58%, P < 0.05) and that of LMP7-B/A was higher (54% vs 31%, P < 0.01) in DM-1 patients than that in controls. In DR3-positive subjects, the frequencies of LMP7 genotypes and alleles showed no differences between DM-1 patients and controls. In DR3-negative subjects, the frequency of LMP7-B/B was decreased (40% vs 61%) and that of LMP7-B/A was increased (55% vs 28%, P < 0.01) in DM-1 patients. The frequencies of LMP7 genotypes and alleles showed no significant differences among different ages of diabetic onset. CONCLUSIONS: LMP7-B/B may be the protective genotype, and LMP7-B/A may be the susceptible genotype of DM-1, and this may not be affected by the DR3 gene. Persons with LMP7-B/B may have a decreased risk, and those with LMP7-B/A have an increased risk suffering from DM-1. The LMP7 gene may not be associated with the age of diabetic onset.

Adolescent↗
PubMed2001

[Estimation of insulin secretion rate in multiple sampled intravenous glucose tolerance test].

OBJECTIVE: To measure and calculate insulin secretion rate(ISR) in multiple sampled intravenous glucose tolerance test (FSIVGTT) according to the two compartment model and standard parameters of the kinetics of connecting peptide (C-P) in vivo. METHODS: 15 subjects with normal glucose tolerance and 11 type 2 diabetic patients took part in the study. Oral glucose tolerance test (OGTT) and FSIVGTT were performed. Glucose concentrations were measured by hexokinase method. Insulin (INS) and C-P concentrations were measured by radioimmunoassay. A computer procedure devised by our laboratory was used to calculate the value of ISR at each time point. RESULTS: In the control group, serum INS and C-P concentrations reached the peak at 4 min, the second peak was not obvious. In type 2 diabetes, only 5 subjects had a small peak within 4 min, two curves reached its peak between 60 and 80 min. In the control group, ISR reached its peak 2 min after injection of glucose, that was earlier than INS and C-P curves in time sequence (P = 0.000), the second obvious peak was shown at 22 min. In type 2 diabetes, an obvious but small peak of ISR was shown at 2 min and all the patients had this peak. CONCLUSIONS: It is necessary to take the process of metabolic clearance of INS and C-P into consideration, when blood concentration of INS and C-P were used as indexes to evaluate the secretion function of beta-cells. The ISR profile is more sensitive for investigation of the second phase of insulin secretion in the control group and the first phase in type 2 diabetes group.

Blood Glucose↗
PubMed2001

[Pre- and post-contrast multiphase helical CT in the diagnosis of hepatic focal nodular hyperplasia].

OBJECTIVE: To analyse the pre- and post-contrast CT findings of liver focal nodular hyperplasia (FNH), so as to improve its diagnostic accuracy. METHODS: Pre-contrast scan and post-contrast tri-phase scan (arterial phase, portal venous phase and delayed phase) were performed in 21 patients with FNH which were proved surgically and pathologically. Transcatheter arterial angiography was performed in 2 patients. RESULTS: On pre-contrast scans, 16 of 21 lesions were hypodense, 5 of 21 were isodense. Twelve of 21 lesions showed punctate, streak and radial scar. On the arterial phase scans, all the lesions were markedly and homogeneously enhanced, except for the central scar. Nine of 21 lesions showed dilated and tortuous arteries at the central or peripheral area. On the portal venous phase scans, focal density was decreased, but still showing hyperdense or slightly hyperdense relative to the normal liver. On the delay phase scans, the lesions changed to isodense or slightly hypodense. Enhanced capsule was observed in 3 patients. On the angiography images, dilated arteries and drainage veins were seen. CONCLUSION: FNH has its special characteristics on the multiphasic helical CT scan. It is of great value in diagnosing the FNH and in choosing the appropriate therapy.

Adolescent↗