Search PubMed⌕ Search

Biomedical subjects

S Gao

Publications and source records attributed to S Gao.

At least 145 records · Page 8Linked to original sources
PubMed1997

Color Doppler monitoring of changes of utero-placental-fetal circulation in normal pregnancy and intrauterine growth retardation.

The utero-placental-fetal circulation (UPFC) of 150 subjects during second and third trimester was examined by using color Doppler. Of them 89 were normal woman and 58 were patients with intrauterine growth retardation IUGR). Our results showed that UPFC was increased gradually during normal pregnant period. In IUGR patients it was revealed that TAV and Q of UmA, UmV and UtA decreased at 20th week of gestation, especially after 30th week. PI, RI and S/D ratio of UmA were increased, but TAV, Q of UmA and UmV were markly reduced, so was UtA. PI were increased, but the changes of RI, S/D ratio in UtA were not significant. Hemodynamical findings of UmA, UmV and UtA were abnormal in 92.53% of IUGR patients. Only 81.03% present abnormal S/D ratio of UmA (P < 0.01) and the difference was statistically significant. Maternal serum E3, HPL level in IUGR were significantly lower than that of the normal. 6KP level was reduced, TXB2/6KP ratio was significantly increased. TXB2/6KP ratio was markedly related with TAV, Q of UmA, UmV and UtA. Our results suggested that using color doppler ultrasound for examination of hemodynamical changes of UmA, UmV and UtA could revealed UPFC function directly. It is one of the best methods for monitoring IUGR and might be used for early diagnosis of IUGR. The main pathophysiological changes of IUGR were UPFC obstruction and placental disfunction.

Adult↗
PubMed1997

Somatic mutation theory, DNA repair rates, and the molecular epidemiology of p53 mutations.

The theory of somatic mutagenesis predicts that the frequency pattern of induced selectable mutations along a gene is the product of the probability patterns of the several sequential steps of mutagenesis, e.g., damage, repair, polymerase misreading, and selection. Together, the variance of these component steps is propagated to generate a mutagen's induced mutational spectrum along a gene. The step with the greatest component of variance will drive most of the variability of the mutation frequency along a gene. This most variable step, for UV-induced mutations, is the cyclobutyl pyrimidine dimer repair rate. The repair rate of cyclopyrimidine dimers is quite variable from nucleotide position to nucleotide position and we show that this variation along the p53 gene drives the C-->T transition frequency of non-melanocytic skin tumors. On showing that the kinetics of cyclopyrimidine dimer repair at any one nucleotide position are first order, we use this kinetic and the somatic mutation theory to derive Leq, the adduct frequency along a gene as presented to a DNA polymerase after a cell population reaches damage-repair equilibrium from a chronic dose of mutagen. Leq is the product of the first two sequential steps of mutagenesis, damage and repair, and the frequency of this product is experimentally mapped using ligation-mediated PCR. The concept of Leq is applied to mutagenesis theory, chronic dose genetic toxicology, genome evolution, and the practical problems of molecular epidemiology.

Animals↗
PubMed1997

Effect of penetration enhancers and iontophoresis on the ultrastructure and cholecystokinin-8 permeability through porcine skin.

The present study explores the effect of chemical penetration enhancers and iontophoresis on the in vitro permeability of cholecystokinin-8 (CCK-8) through porcine epidermis and on the ultrastructural changes in stratum corneum as observed by transmission electron microscopy (TEM). Enhancer [i.e., ethanol (EtOH), and 10% oleic acid in combination with ethanol (OA/EtOH)] pretreatment significantly increased (p < 0.01) the permeability coefficient of CCK-8 in comparison with the control (pretreated epidermis without enhancer). Iontophoresis further increased the permeability of CCK-8 (p < 0.01) through the enhancer-pretreated epidermis in comparison with the control. These results showed the synergistic effect of iontophoresis and enhancers such as OA/EtOH that provides an additional driving force to maintain and control the target flux of CCK-8. The ultrastructure of stratum corneum treated with ethanol demonstrated a loss of structural components in the superficial stratum corneum cell layers. OA/EtOH transformed the highly compact cells of stratum corneum into a looser network of filaments, creating an increased free volume and greater intracellular surface area. Treatment of stratum corneum with OA/EtOH followed by iontophoresis resulted in further swelling of stratum corneum cell layers. In conclusion, OA/EtOH in combination with iontophoresis increased the permeability of CCK-8 by loosening and swelling of stratum corneum cell layers.

Animals↗
PubMed1997

The association between Apo E genotype and depressive symptoms in elderly African-American subjects.

In this study of 138 elderly subjects (112 without and 26 with dementia) obtained from a community sample of elderly African-American subjects, there were no significant differences in mean Geriatric Depression Scale scores by Apo E epsilon 4 status for dementia or nondementia subjects. Three subjects received a diagnosis of major depressive disorder. None of these subjects were Apo E epsilon 4-positive. These results do not support an association between depressive symptoms and Apo E allele status in this elderly African-American population.

Aged↗
PubMed1997

Vascular lesions in Chinese patients with transient ischemic attacks.

We studied 96 Chinese patients with TIAs using transcranial Doppler and duplex ultrasonography. We found intracranial stenosis or occlusion in 51% of cases and extracranial disease in 19% of cases. The most common intracranial lesion was stenosis of the terminal internal carotid artery or proximal middle cerebral artery, whereas the most common extracranial lesion was stenosis of the carotid bifurcation.

Adolescent↗
PubMed1997

Universal standardization of bone density measurements: a method with optimal properties for calibration among several instruments.

The International Dual-Photon X-Ray Absorptiometry (DXA) Standardization Committee (IDSC) conducted a cross-calibration study among three models of DXA machines from three different manufacturers. In that study, 100 subjects were scanned on all three machines. A set of equations were derived to convert bone mineral density (BMD) on each machine to a "standardized BMD" (sBMD) such that sBMD from the same subject derived from different machines would be approximately the same. In a reanalysis of the cross-calibration data, we showed that the conversion method used in the IDSC study did not achieve several optimal properties desirable in such conversions. We derived new conversion equations to sBMD based on minimizing differences among sBMD from the three machines. More important is that the new conversions have no residual bias that was present in the IDSC conversions. The performance of the methods were compared on the cross-calibration data as well as an external data set. We conclude that the IDSC conversions are adequate for clinical use on other machines worldwide, but that researchers should standardize their own machines in a laboratory using the new method.

Absorptiometry, Photon↗
PubMed1997

[Pedicled omentum graft for improvement of late-blood supply after myocardial revascularization with Nd:YAG laser in the treatment of ischemic heart disease].

26 dogs were devided into 3 groups. Selected left coronary artery branches of all dogs were ligated to make the models of myocardial infarction. The control group of 10 dogs received ligation of selected coronary artery branches(L group) only. Eight dogs were revascularized by Nd:YAG laser (LL group), and 8 dogs were revascularized and covered with pedicled omentum. All dogs were monitored by ECG, cardiac output, fractional 86Rb uptake and histological examination. The results showed that laser channels can perfuse ischemic myocardium and recover myocardial circulation to improve cardiac function immediately. However, the laser channels were closed after 4 weeks by clot, fibrosis and scarring which caused by thermal damage of Nd:YAG laser. The late result of laser myocardial revascularization with pedicled omentum graft is more better in perfusing myocardium and improving cardiac function than sole laser myocardial revascularization.

Animals↗
PubMed1997

[An experimental study on effect of atrial natriuretic peptide on intraocular pressure of white rabbits].

OBJECTIVE: To study the therapeutic effect of atrial natriuretic peptide (ANP) on glaucoma. METHODS: Various doses of ANP were injected subconjunctivally in albino rabbits, and their effects on intraocular pressures (IOPs) were observed. RESULTS: The IOPs were significantly decreased by the subconjunctival injection of 20, 30, 40 micrograms of ANP, and with a dose of 40 micrograms, the maximum effect of IOP lowering of 0.88-0.15 kPa maintaining for the longest time 7.5 hours was obtained. Generally, one hour after the injection, the maximum effect could be seen. A dose-effect relationship that is the degree of the reduction of IOP increasing with the dose increase of ANP could be observed. CONCLUSION: This study indicates that ANP might play an effective therapeutic role in glaucoma.

Animals↗
PubMed1997

[Surgical treatment of non-thoracotraumatic pneumomediastinum].

The experience of surgical treatment of non-thoracotraumatic pneumomediastinum in 48 cases was summarized. The etiology, classification, pathology, and surgical treatment of non-thoracotraumatic pneumomediastinum were discussed. We conclude that most non-thoracotraumatic pneumomediastinum was complicated by secondary diseases. Therefore, the effective treatments for primary diseases are important. A satisfactory effect must be based on different surgical techniques according to the different clinical symptoms and age of patients.

Adolescent↗
PubMed1997

[Preliminary studies on outer membrane protein (OMP) patterns of Escherichia coli O1, O2 and O78 isolates of chicken origin].

Omp patterns of twenty-five isolates of Escherichia coli serotype O1, O2 and O78 of chicken origin from Jiangsu area were determined. The outer membrane proteins of these isolates were isolated with the improved N-lauroylsarcosine method and analyzed by SDS-PAGE. Major outer membrane proteins bands contributed for OMP patterns were visualized with Coomassie brilliant blue staining. Two OMP patterns were divided in eight of O1 isolates and nine O2 isolates respectively. Among these OMP patterns, 1 OMP pattern was shared by these 2 different O serotypes isolates, and eight of O78 isolates also shared this OMP pattern. These results indicated that the OMP patterns of avian pathogenic Escherichia coli isolates of O1, O2 and O78 from this area were heterogeneous, and the same OMP patterns was presented in these 3 serotypes.

Animals↗
PubMed1997

[Determination of calcium, magnesium and potassium in nurtured cell by AAS with quick-pulsed nebulization technique and NaOH base digestion].

The sample is digested with 6% NaOH solution and an amount of 50 microl is used for protein content analysis by the method of Comassie Brilliant Blue G250, the residual is diluted with equal 0.4% Lathanurm-EDTA solution. Its Calcium magensium and potassium content are determined by AAS. With quick-pulsed nebulization technique. When a self-made micro-sampling device is used, 20microl of sample volume is needed and it is only the 1/10 approximately 1/20 of the sample volume required for conventional determination. Sensitivity, precision and rate of recovery agree well with those using regular wet ashing method.

Animals↗
PubMed1997

Methods for comparing the means of two independent log-normal samples.

Standard methods of using the t-test and the Wilcoxon test have deficiencies for comparing the means of two skewed log-normal samples. In this paper, we propose two new methods to overcome these deficiencies: (1) a likelihood-based approach and (2) a bootstrap-based approach. Our simulation study shows that the likelihood-based approach is the best in terms of the type I error rate and power when data follow a log-normal distribution.

Biometry↗
PubMed1997

The evaluation of intra- and extra-cranial circulation in subclavian steal syndrome.

OBJECTIVE: To compare the efficacy of transcranial Doppler ultrasound (TCD) and digital subtraction angiography (DSA) in identifying the clinical and hemodynamic relationship between intra- and extra-cranial circulation and subclavian steal syndrome. METHODS: Sixteen patients were collected. The intra- and extra-cranial arteries were insonated with Doppler ultrasound. DSA and brain CT were performed in all patients. The relationship between the grade of arterial stenosis showing in DSA and the flow direction showing in TCD was studied. RESULTS: TCD showed reversal flow of the vertebrobasilar artery in 13 patients, normal flow in 3, which was influenced obviously by fist-clenching. In the hyperemia test, the flow velocity and the direction changed significantly in all patients. The steal phenomenon of the middle cerebral artery (MCA) was coincident with that of the arterial cerebral artery (ACA) in 2 cases. Stenosis of MCA or ACA was found in 5 cases (31%). Nine patients were treated with arterial bypass or angioplasty. TCD was performed during the follow-up. CONCLUSIONS: Reversal flow of the vertebral artery may occur in rest or only in exercise, depending on the grade of subclavian arterial stenosis. Hyperemia test is the most sensitive index. It is necessary to monitor blood flow in the MCA and basilar artery in hyperemia test. The coexistence of intra- and extra-cranial arterial stenosis is common.

Adult↗
PubMed1997

[Diagnostic value of endometrial assessment by transvaginal ultrasonography in patients with postmenopausal bleeding].

OBJECTIVE: To assess the value of endometrial transvaginal sonography in diagnosis of patients with postmenopausal bleeding. METHODS: High resolution transvaginal ultrasonographic examination was performed in 192 patients with postmenopausal bleeding before fractional uterine curettage. The results of endometrial sonogram were compared with endometrial histological findings. RESULTS: Seventy-seven cases had endometrial thickness < or = 4mm. 74 of them (96.1%) showed physiological changes by pathological examination. Only 3 were endometrial cancer. In contrast, in 115 patients who had endometrial thickness > or = 5mm, 59 (51.3%) had endometrial cancer. CONCLUSION: Transvaginal ultrasonography may be used as a screening procedure in patients with postmenopausal bleeding. Diagnostic uterine curettage may be avoided in patients who had endometrial thickness < or = 4mm.

Aged↗
PubMed1997

Guillain-Barré syndrome: clinical analysis and pathological study on sural nerve biopsy of forty cases.

OBJECTIVE: To make clinical analysis and pathological study on 40-case Gullain-Barré syndrome with sural nerve biopsy. METHODS: A total of 90 cases of GBS were retrospectively analyzed of which sural nerve biopsies were performed in 40 cases. The type of GBS was determined according to Asbury and Ropper criteria, and its correlation with pathological findings was studied. RESULTS: In the 40 biopsy cases, demyelination was the predominant pathological change in 38 cases. Mild axonal degeneration was also seen in 13 of the 38 cases. Prominent axonal degeneration was seen in only 2 of 13 cases. The increased monocyte infiltration and varied capillary permeability were observed in 19 of 25 cases. Onion-bulb like changes were seen in 6 cases. CONCLUSION: We studied the correlation between paresthesia and the pathological findings of sural nerve biopsy and concluded that sural nerve biopsy is very useful in the diagnosis of GBS and its variant.

Adolescent↗
PubMed1997

Clinical, pathologic and genetic studies on mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes.

OBJECTIVE: To study the clinical, pathological and genetic characteristics of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). METHODS: Eight cases of MELAS (6 of them were from 2 families) underwent clinical study, muscle biopsy, autopsy on one patient, brain biopsy on one patient and genetic research. RESULTS: In clinical report the average age of onset was 10-22 years old. Four cases from one family were 3 brothers and their nephew (sister's son). The death age of the three brothers was 16-20 years. Two cases from another family were a brother and a sister. The six patients of the two families showed the typical inherited characters of MELAS. The symptoms were myoclonic epilepsy, stroke-like episodes, paralysis of limbs, progressive mental retardation and neurological deaf. CT showed calcification in globus pallidus and MRI demonstrated clearly the abnormal prolongation of T2-weighed signals that distributed in frontal, parietal, occipital and temporal cortex as multiple focal, cystic and laminar necrotic areas. Pathological studies on brain showed multi-focal, cystic, and laminar or spongy necrotic abnormality primarily in gray matter of frontal, parental, temporal and occipital cortex. Decrease and loss of nerve fibers of the sub-cortical white matters of the lesion areas of cortex and calcification of globus pallidus were also observed. Red ragged fibers (RRF) and abnormal mitochondron were found by muscle biopsies. A point mutation (A-G transition) at nt 4243 in the mitochondrial tRNA Leu (UUR) was confirmed by using PCR and Southern Blot. CONCLUSION: Although great progress has been made in the clinical, pathological and genetic research of MELAS, the pathogenesis of the disease remains further research.

Adolescent↗
PubMed1997

[Reconstruction of lacrimal passage in repair of oblique facial cleft].

For the reconstruction of lacrimal passage in obligue facial cleft, three methods were performed in 4 cases. According to the difference in local pathology canaliculorhinestomy, transfer of vein or oral mucosa, or modified dacryocystorhinostomy was performed. The patients were followed for 6 to 12 months with satisfacting results.

Abnormalities, Multiple↗