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Biomedical subjects

L Zhou

Publications and source records attributed to L Zhou.

At least 271 records · Page 15Linked to original sources
PubMed1999

Levels of mineralocorticoids in whites and blacks.

Blacks appear, on average, to retain more Na than whites. A higher production rate of mineralocorticoids could explain the greater Na retention in blacks. Although production of aldosterone has been shown to be lower in blacks, the level of another mineralocorticoid may be increased. Plasma levels of deoxycorticosterone and cortisol were measured in young whites (n=23; age=16.4+/-3.1[SD] years) and young blacks (n=25; age=13.8+/-1.3 years). Blacks had lower plasma levels of renin activity and aldosterone and lower urinary aldosterone excretion rates; thus, they appeared to be representative of blacks that retain additional Na. Plasma deoxycorticosterone levels were lower in blacks than in whites both at baseline (247+/-161 versus 381+/-270 pmol/L, P=0.048) and after stimulation with adrenocorticotropic hormone (822+/-294 versus 1127+/-628 pmol/L at 30 minutes, P=0.047; 925+/-366 versus 1440+/-834 pmol/L at 60 minutes, P=0.013). Cortisol levels were also lower in blacks at baseline (P=0.014) but were not significantly different from levels in whites after stimulation with adrenocorticotropic hormone. In a larger cohort of 407 whites (age=12.0+/-2.9 years) and 247 blacks (age=12.9+/-3.1 years), 18-hydroxycortisol excretion rates were also lower in blacks (P=0. 021). In conclusion, increased Na retention in blacks does not appear to be secondary to increased production of either aldosterone, deoxycorticosterone, cortisol, or 18-hydroxycortisol. A primary renal mechanism may mediate the increase in Na reabsorption in blacks.

Adolescent↗
PubMed1999

Genetic variants in the epithelial sodium channel in relation to aldosterone and potassium excretion and risk for hypertension.

Renin and aldosterone secretion is often lower in blacks than in whites, characteristics that resemble a milder form of Liddle syndrome in which a mutation in the amiloride-sensitive epithelial sodium channel (ENaC) of the kidney results in enhanced resorption of sodium. In the present study, we looked for evidence that the intrinsic level of ENaC activity is indeed higher in blacks than in whites. In overnight urine samples collected from young people (249 white and 181 black subjects, mean age 13.4 years), the urinary aldosterone/potassium ratio, which is typically very low in Liddle syndrome, was lower in blacks than in whites: 0.421+/-0.024 (mean+/-SE) versus 0.582+/-0.016 nmol/mmol (P<0.0001). In addition, all but 1 of 5 molecular variants in ENaC were much more common in blacks than in whites. G442V in the beta-subunit, present in 16% of the blacks and in only 1 white, was associated with parameters reflective of a greater Na retention and potentially a higher ENaC activity: a lower plasma aldosterone concentration (P=0.070), a lower urinary aldosterone excretion rate (P=0.052), a higher potassium excretion rate (P=0.048), and a lower urinary aldosterone/potassium ratio (P=0.027). In a second cohort consisting of 126 black and 161 white normotensive subjects and 232 black and 188 white hypertensive subjects, betaG442V did not show a significant association with hypertension (P=0.089). On the other hand, a variant that was twice as common in whites, alphaT663A, was associated with being normotensive both in blacks (P=0.018) and in whites (P=0.034). Expression of either betaG442V or alphaT663A in Xenopus oocytes did not result in a change in basal Na current, consistent with the variants being in linkage disequilibrium with alleles at active loci. In conclusion, several lines of evidence are presented to suggest that ENaC activity is higher in blacks than in whites, which could contribute to racial differences in Na retention and the risk for hypertension.

Adolescent↗
PubMed1999

Action of insulin receptor substrate-3 (IRS-3) and IRS-4 to stimulate translocation of GLUT4 in rat adipose cells.

The insulin receptor initiates insulin action by phosphorylating multiple intracellular substrates. Previously, we have demonstrated that insulin receptor substrates (IRS)-1 and -2 can mediate insulin's action to promote translocation of GLUT4 glucose transporters to the cell surface in rat adipose cells. Although IRS-1, -2, and -4 are similar in overall structure, IRS-3 is approximately 50% shorter and differs with respect to sites of tyrosine phosphorylation. Nevertheless, as demonstrated in this study, both IRS-3 and IRS-4 can also stimulate translocation of GLUT4. Rat adipose cells were cotransfected with expression vectors for hemagglutinin (HA) epitope-tagged GLUT4 (GLUT4-HA) and human IRS-1, murine IRS-3, or human IRS-4. Overexpression of IRS-1 led to a 2-fold increase in cell surface GLUT4-HA in cells incubated in the absence of insulin; overexpression of either IRS-3 or IRS-4 elicited a larger increase in cell surface GLUT4-HA. Indeed, the effect of IRS-3 in the absence of insulin was approximately 40% greater than the effect of a maximally stimulating concentration of insulin in cells not overexpressing IRS proteins. Because phosphatidylinositol (PI) 3-kinase is essential for insulin-stimulated translocation of GLUT4, we also studied a mutant IRS-3 molecule (IRS-3-F4) in which Phe was substituted for Tyr in all four YXXM motifs (the phosphorylation sites predicted to bind to and activate PI 3-kinase). Interestingly, overexpression of IRS-3-F4 did not promote translocation of GLUT4-HA, but actually inhibited the ability of insulin to stimulate translocation of GLUT4-HA to the cell surface. Our data suggest that IRS-3 and IRS-4 are capable of mediating PI 3-kinase-dependent metabolic actions of insulin in adipose cells, and that IRS proteins play a physiological role in mediating translocation of GLUT4.

Adaptor Proteins, Signal Transducing↗
PubMed1999

A novel method for analysis of nuclear receptor function at natural promoters: peroxisome proliferator-activated receptor gamma agonist actions on aP2 gene expression detected using branched DNA messenger RNA quantitation.

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, plays an essential role in the mediation of the actions of antidiabetic drugs known as thiazolidinediones (TZDs). PPARgamma activates many target genes involved in lipid anabolism including the adipocyte fatty acid binding protein (aP2). In this study, induction of aP2 gene expression by PPARgamma agonists was examined in both cultured cells and diabetic mice using branched DNA (bDNA)-mediated mRNA quantitation. bDNA technology allows for the direct measurement of a particular mRNA directly within cellular lysate using a 96-well plate format in a time frame comparable to a reporter gene assay. In cultured human subcutaneous preadipocytes, the TZDs, troglitazone and BRL-49653, both rapidly induced aP2 mRNA as detected with the bDNA method. In these cells, the effect of BRL-49653 on aP2 mRNA levels was detectable as early as 30 min after treatment (47% increase) and was maximal after 24 h of treatment (12-fold increase). The effects of troglitazone on aP2 mRNA induction were similar to those of BRL-49653 except that the maximal level of induction was consistently lower (e.g. 24 h treatment = 4-fold increase). Dose-response relationships for both of the TZDs were also determined using the 24-h treatment time point. EC50s for both BRL-49653 and troglitazone were estimated to be 80 nM and 690 nM, respectively. A natural PPARgamma ligand, 15-deoxy-delta12,14-PGJ2, was also active in this assay with a maximal induction of aP2 mRNA of approximately 5-fold when tested at 1 microM. Since the PPARgamma:retinoid X receptor (RXR) heterodimer has been characterized as a permissive heterodimer with respect to RXR ligands, the ability of 9-cis-retinoic acid (9-cis-RA) to induce aP2 mRNA was examined. Although 9-cis-RA had very low efficacy (2-fold induction), the maximal effect was reached at 100 nM. No synergism or additivity in aP2 mRNA induction was detected when 9-cis-RA was included with either of the TZDs used in this study. Significant induction of aP2 mRNA in bone marrow of db/db mice treated with either troglitazone or BRL-49653 was also detected, indicating that the bDNA assay may be a simple method to monitor nuclear receptor target gene induction in vivo.

Adipocytes↗
PubMed1999

Protection of myocardial mitochondria against oxidative damage by selenium-containing abzyme m4G3.

Selenium-containing abzyme (m4G3) was prepared and its protection of myocardial mitochondria against oxidative damage was studied using the swelling of mitochondria, quantity of lipid peroxidation products, and change in cytochrome-c oxidase activity as a measure of mitochondrial damage. The results showed that m4G3 could inhibit mitochondrial damage caused by the hypoxanthine-xanthine oxidase system in vitro. Electronic spin resonance (ESR) studies demonstrated that m4G3 could decrease the amount of free radicals generated in the damage system.

Animals↗
PubMed1999

Rapid assessment of the effects of restraint on self-injury and adaptive behavior.

We evaluated the effects of restraint on occurrences of self-injurious behavior (SIB) and adaptive responses exhibited by 2 individuals across eight response-effort conditions: baseline (no restraints); restraint sleeves without stays; restraints with 5, 10, 15, 20, or 25 thin metal stays; and restraints with five thick metal stays. From this analysis, we identified a restraint level for each participant that reduced SIB but did not inhibit adaptive responding.

Adaptation, Psychological↗
PubMed1999

Multiple cyclic nucleotide phosphodiesterases in human trabecular meshwork cells.

PURPOSE: To characterize cyclic nucleotide phosphodiesterase isozyme activities in human trabecular meshwork cells and primary cultures of porcine trabecular meshwork cells. METHODS: Radioimmunoassay of acetylated acid extracts was used to determine changes in cyclic adenosine monophosphate (cAMP) and cyclic quanosine monophosphate (cGMP) in human trabecular meshwork cells treated with phosphodiesterase isoform selective inhibitors. Cyclic nucleotide phosphodiesterase activities were measured using the two-step radioisotope procedure (Thompson). Enzyme activities in the supernatant of human cells were fractionated using anion-exchange chromatography. Additionally, human and porcine trabecular meshwork cell transcripts of phosphodiesterase family-specific isoforms were studied by reverse transcription-polymerase chain reaction and nucleotide sequencing. RESULTS: In intact human cells, selective inhibitors for phosphodiesterase 4 (rolipram) and 5 (E4021) gene families were effective in augmenting cyclic nucleotide accumulation in response to isoproterenol or sodium nitroprusside, respectively. cAMP and cGMP hydrolytic activities, resolved using Trisacryl M anion-exchange chromatography, showed a cAMP phosphodiesterase peak that was minimally sensitivity to cGMP but modestly inhibited by rolipram and a cGMP phosphodiesterase peak that was sensitive to inhibition by E4021. Further evaluation of the cGMP phosphodiesterase demonstrated Michaelis-Menten kinetics and competitive inhibition by E4021. Messenger RNA transcripts for phosphodiesterase 4, 5, and 7 isozymes were isolated in human trabecular meshwork cells. However, in porcine trabecular meshwork cells only isozymes for phosphodiesterase 4 and 5 isozymes were detected. CONCLUSIONS: Human trabecular meshwork cells express phosphodiesterase 4, 5, and 7 gene family isoforms and enzyme activities, suggesting that selective isoform inhibitors could be used to augment the actions of antiglaucoma drugs that use cyclic nucleotides as second messengers.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1999

[Identification of mutations of SRD5A2 gene and SRY gene in patients with hypospadias].

OBJECTIVE: To identify possible molecular mechanism underlined hypospadias and any relationship of the mutations of SRD5A2 gene and SRY gene to hypospadias. METHODS: Twenty-three blood samples from the patients with hypospadias were obtained from Aug.1996 to Jan. 1998. DNA was extracted from blood leukocytes. Exons 1 to 5 of the SRD5A2 gene and exon of the SRY gene were amplified by PCR. Mutation detection was performed using PCR-SSCP/silver staining and direct DNA sequencing. RESULTS: In 3 cases (named 5R2-China-1, 5R2-China-2, and 5R2-China-3), DNA sequencing revealed that a homozygous change from nucleotide G to A occurred in 5R2-China-1 and 2, leading to a substitution of glutamine to arginine in the codon 227(Arg 227 to Gln). In the third patient (5R2-China-3), DNA sequencing revealed two different heterozygous mutations(Arg 227 to Gln, Phe 186 to Leu) in exon 4 of the SRD5A2 gene. No mutation of SRY gene was found in all patients. CONCLUSION: The mutation of SRD5A2 gene affects the differentiation of the external genitalia and may play a role in the etiology of hypospadias. Since no mutation of SRY gene was found, this study might suggest that the mutation of SRY gene is not an important event in hypospadias. Codon 227 is a hotspot site of mutation within the gene. The mutation of codon 186(Phe 186Leu) represents a new form of SRD5A2 mutation.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

[Detection of R277Q mutation of SRD5alpha2 gene by amplification refractory mutation system].

OBJECTIVE: To set up a simple method for identifying the mutation of R227Q of SRD5alpha2 gene which is one of the most common mutations in congenital hypospadias in China. METHODS: The amplification refractory mutation system(ARMS) was employed in detecting the SRD5alpha2 gene R227Q mutation in congenital hypospadias confirmed by PCR-SSCP and DNA sequencing. RESULTS: The ARMS was successfully applied to the detection of the R227Q mutation of SRD5alpha2 gene. Three out of 23 congenital hypospadias were positive for R227Q mutation. The mutations determined by ARMS were in full agreement with those obtained by the DNA sequencing. CONCLUSION: This is a simple, rapid and accurate method. It can be used for detecting the SRD5alpha2 gene R227Q mutation in congenital hypospadias and male pseudohermaphroditism.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

[Ureaplasma urealyticum infection and premature delivery or premature rupture of the membrane].

OBJECTIVE: To evaluate the relationships between ureaplasma urealyticum (UU) infection and premature delivery or premature rupture of the membrane (PROM). METHODS: The cervical swabs, fetal membrane and umbilical cord from 46 cases of PROM, 7 cases of premature delivery (study group), and 32 normal pregnancies (control group) were cultured for UU. Some of these placenta tissues were examined under electron microscopy, and compared with the purified UU. RESULTS: The detective rates of UU were both 73.6% (39/53) in the cervix and fetal membrane of the study group, and to compare with the control group (40.6%, 13/32 and 15.6%, 5/32 respectively), significant differences were shown (P < 0.01, P < 0.001). The prevalence rate of perinatal mortality, stillbirth and low birth weight in UU-positive cases (34.1%, 15/44) was significantly higher than that in UU-negative cases (7.3%, 3/41, P < 0.01). Electron microscopy demonstrated that large amount of small multiplicated UU particles deposited around the nuclear membrane of the cytotrophoblasts and in the collagen fibers from the placenta of PROM, and its shape was in consistent with that of the purified UU. In contrast, no UU particles was seen in the normal control group. CONCLUSION: The results show that UU is responsible for some cases of premature delivery, low birth weight and PROM. The multiplication of UU within the trophoblasts may disrupt cell structure which could interfere the normal fetal development.

Adult↗
PubMed1999

Medulloblastoma.

OBJECTIVE: To elucidate the diagnosis, treatment and prognosis of medulloblastoma in both children and adults. METHODS: A retrospective review was conducted in 80 patients with medulloblastoma confirmed pathologically during the period of 1984 and 1995. Multivariate analysis and comparison were made of the therapeutic effects of operation, radiotherapy and chemotherapy as well as the survival period. RESULTS: There were 42 males and 38 females with average age at diagnosis being 9.1 years in children and 25.1 years in adults. All patients were operated on to remove the tumour. Cerebral aqueduct re-opening was got through in 54 cases (67.5%), and Torkilsen's shunt was carried out at the same time for the rest patients. Seventeen patients had ventriculoperitoneal shunt, and 13 of them were performed after surgical excision of the tumour. Complete follow-up information was obtained in 61 patients (76%) for a period of 6 months to 14 years. During the follow-up, 27 patients received postoperative craniospinal irradiation, and 27 local radiation. Fourteen patients were subjected to adjuvant chemotherapy. The overall 5-year and 10-year survival rates were 50.5% and 27.89% respectively. The 5-year survival rate was higher in adults than in children (P < 0.05), whereas the 10-year survival rate was similar. Thirty-two patients died of relapse or metastasis between 6 months and 10 years after initial surgical therapy, and the mean recurrence time was 3.5 years. CONCLUSIONS: Operation and postoperative regular radiotherapy were important therapeutic modalities for medulloblastoma. Total or subtotal removal of the tumour combined with craniospinal radiotherapy can improve patients' survival rate. The survival period of medulloblastoma patients is consistent with Collins' law, that is, the period of risk for survival is the age at initial diagnosis plus 9 months. Only few patients can gain long-term survival.

Adolescent↗
PubMed1999

Surgical treatment of trigeminal neurinomas.

OBJECTIVE: To investigate the best surgical approach for the removal of trigeminal neurinomas (TNs). METHODS: A retrospective analysis of 75' patients with TNs in Huashan Hospital was carried out. RESULTS: In the early group (1978-1984), a series of conventional intradural approaches were used; in the late group (1985-1995), an epidural approach via the skull-base craniotomy was used. Total tumor removal was achieved in 58% (20/35) of patients in the early group and 80% (32/40) in the late group (P < 0.025). Temporary and permanent cranial nerve morbidity were 62.7% and 37% in the early group and 28.1% and 10% in the late group (P < 0.001). CONCLUSION: The best microsurgical approach for the removal of trigeminal neurinomas except those confined to the posterior fossa is epidural approach or epidurotransduro-transtentorial approach via the skull-base craniotomy.

Cranial Nerve Neoplasms↗
PubMed1999

Neuronavigation for the resection of cavernous angiomas.

OBJECTIVE: To introduce the use of the StealthStation neuronavigator combined with preoperative computerized tomography (CT) in resection of intracranial cavernous angiomas (CAs). METHODS: The StealthStation neuronavigator was used to provide a realtime correlation of the operating field and the computerized images in 6 patients with CAs. All patients suffered from epileptic seizures. Four patients underwent keyhole surgery and 2 underwent small skin-flap craniotomy. The mean follow-up was 4.5 months. RESULTS: With the guidance of neuronavigator, lesionectomy associated with removal of hemosiderin deposition, gliosis and calcification was performed precisely. The mean fiducial error was from 1.65 mm to 4.53 mm, the predicted accuracy at 10 cm was between 1.82 mm and 3.28 mm, and the sustained accuracy ranged from 0.50 mm to 3.45 mm. CONCLUSION: The StealthStation neuronavigator is reliable and accurate in the resection of CAs.

Adolescent↗
PubMed1999

[Combined retropubo-perineal radical prostatectomy and a new method of reconstructing the posterior urethra].

OBJECTIVE: To evaluate the efficacy of a new method of reconstructing the posterior urethra for the combined retropubo-perineal radical prostatectomy. METHODS: Six cases of prostate cancer were treated by operative method mentioned previously. For the operation, the routine retropubic radical prostatectomy was carried out first and then through the perineal incision, 4-6 cm of the residual urethra was seperated, held upward and anastomosed with the bladder neck. RESULTS: The urinary catheter was maintained for 14-28 days postoperatively on an average of 21.6 days. After 2-17 (average, 7.3) months of follow-up, 5 cases urinated smoothly and were completely dry for voiding. One case suffered from the infection of the perineal incision and dysuria after the removal of the urinary catheter and needed urethral dilatation periodically. CONCLUSION: The new method of reconstruction of the posterior urethra for the combined retropubo-perineal radical prostatectomy makes a better operative exposure, a better mucoso-mucosa anastomosis, and reduces the tension of anastomosis. It can decrease the incidence of urinary incontinence and urethral stenosis obviously. Its long-term efficacy should be observed in more cases with longer follow-up.

Adenocarcinoma↗
PubMed1999

[The value of "occult blood bead" in detection of upper digestive tract disorders with bleeding].

OBJECTIVE: To evaluate the usefulness of "occult blood bead" (OBB) test in the screening of gastric and esophageal cancers. METHODS: In the study, subjects with upper gastro-intestinal (GI) symptoms received gastric OBB test before gastroscopic examination. OBB test was scored as +(-)+++ according to the intensity of reactions. The sensitivity, specificity, and likelihood ratio of OBB test were evaluated according to results of gastroscopic and/or pathological examination. RESULTS: Among 5,217 subjects, 2,403 showed positive OBB test (46.1%). In this series, 202 cases of malignant disorders were detected (gastric cancer in 155 and esophageal cancer in 47). There were 69 cancer cases among 1847 subjects presenting "+" OBB test, with a cancer detection rate of 3.7%. In 393 subjects presenting "++" OBB test, 28 were cancer (7.1%); while in 163 subjects presenting "+++" OBB test, 34 were diagnosed as gastric or esophageal cancer with a detection rate of 20.9%. The sensitivity of OBB test in detection of gastric and esophageal cancer was 0.65, the specificity was 0.55, likelihood ratio was 1.43 and the Youden Index was 0.2. CONCLUSION: OBB test provides a new, simple and non-invasive method for detection of upper digestive tract bleeding. For detection of upper GI carcinomas it presents a reasonable sensitivity and specificity in a group of subjects with upper GI symptoms. OBB test can be used as a prelimnary screening tool for gastric and esophageal cancer in asymptomatic general population.

Adolescent↗
PubMed1999

[Clinical analysis of 935 cases of non-Hodgkin's lymphoma].

OBJECTIVE: To analyze the results of treatment of non-Hodgkin's lymphoma (NHL). METHODS: The results of treatment in 935 NHL patients were reviewed according to life table Log rank analysis. RESULTS: Patients with moderately malignant NHL had better long-term survival, as compared with other pathologic types (P < 0.05). Patients in clinical stage I had better prognosis than those in stage II, III and IV (P < 0.001). Patients achieved CR as short-term response had the best prognosis. When analyzed according to treatment modalities, the long-term effect was seemingly better in patients treated with chemotherapy + radiotherapy than in patients treated with radiotherapy alone or chemotherapy alone, but the different was statistically insignificant. If the results are compared between patients treated in 1983 through 1988 and those in 1989 through 1993, there was marked improvement in long-term survival in the latter time period during which patients were given more intensive chemotherapy. CONCLUSION: The long-term survival rate of patients with NHL was closely related to pathologic types, clinical stage, short-term therapeutic effect. Intensive chemotherapy help improve prognosis. The leaping manner of NHL dissemination requires sufficient systematic therapy.

Adolescent↗
PubMed1999

[Clinical study on retarding aging effect of tongbu recipe to traditional Chinese medicine].

OBJECTIVE: To study the mechanism of Tongbu No. 1 (TB1, a prescription for reinforcing Kidney and Spleen, clearing up the bowel viscera to send Turbid downward and regulating Qi and blood) in retarding aging. METHODS: A controlled, multiple indexes study was conducted in 56 old subjects randomized into 3 groups. RESULTS: TB1 (containing ginseng leaf, cistanche, fleeceflower root, immature bitter orange, rhubarb, etc) could improve various symptoms of aging, and had the effect in regulating immune and endocrinal function, scavenging free radicals and adjusting coli flora. The effects of TB1 and TB2 (containing ginseng leaf, cistanche and fleeceflower root) were different significantly (P < 0.05, P < 0.01). CONCLUSION: TB1 has a good comprehensive effect in retarding aging.

Aged↗