PubMed Health⌕ Search

Biomedical subjects

S Qiu

Publications and source records attributed to S Qiu.

At least 37 records · Page 2Linked to original sources
PubMed1998

A branched stem-loop structure in the M-site of bacteriophage Qbeta RNA is important for template recognition by Qbeta replicase holoenzyme.

An internal site on bacteriophage Qbeta RNA, the M-site (map position 2545 to 2867), was recently shown by us to be required for the efficient initiation of minus strand synthesis by Qbeta replicase. In a more detailed mutational analysis, we show here that the essential elements within the M-site consist of two successive stem-loop structures followed by a bulge loop of unpaired purines, located at nucleotides 2696 to 2754 on the tip of a long, imperfectly base-paired stalk. Mutational changes affecting the sequences of paired or unpaired nucleotides in this segment reduced the template efficiency only mildly. The only severe effects were observed when one of the helical stems or the unpaired bulge was completely deleted or substantially shortened. We conclude that the three-dimensional backbone arrangement of these three elements constitutes the feature recognized by replicase. The role of the long stalk remains undetermined, because mutations that either stabilized or disrupted its base-pairing barely affected template activity, and even deletion of a major portion of one of its strands did not cause complete inactivation. Earlier evidence had implicated protein S1 (the alpha subunit of replicase) as the mediator of the M-site interaction. The lack of an active M-site on the Qbeta RNA template has the same quantitative and qualitative effects on template recognition as the absence of the S1 protein from replicase in the presence of wild-type RNA. We therefore believe that the M-site interaction explains most of the role of S1 protein in the replication of Qbeta RNA by replicase.

Allolevivirus↗
PubMed1998

Alkylation of 2'-deoxynucleosides and DNA by the Premarin metabolite 4-hydroxyequilenin semiquinone radical.

Premarin (Wyeth-Ayerst) is the estrogen replacement treatment of choice and continues to be one of the most widely dispensed prescriptions in the United States. In addition to endogenous estrogens, Premarin contains unsaturated estrogens including equilenin. We synthesized the catechol metabolite of equilenin, 4-hydroxyequilenin (4-OHEN), and found that the semiquinone radical of 4-OHEN reacted with 2'-deoxynucleosides generating very unusual adducts. 2'-Deoxyguanosine (dG), 2'-deoxyadenosine (dA), or 2'-deoxycytosine (dC) all gave four isomers, but no product was observed for thymidine under similar physiological conditions. The structures of these adducts were determined by electrospray mass spectrometry and NMR experiments including 1H, 13C, DQF-COSY, ROESY, HOHAHA, HMQC, and HMBC. The spectral data show that dG forms a cyclic adduct with the 4-OHEN producing 2-N1,3-N2-deoxyguanosyl-1,3-dihydroxy-5,7,9(10)-estratriene-4,17-d ione. Similarly, reaction with dA produced 1-N6,3-C2-deoxyadenosyl-2,3-dihydroxy-5,7,9(10)-estratriene-4,17-d ione, and incubations with dC resulted in 1-N3,3-N4-deoxycytosyl-2,3-dihydroxy-5,7,9(10)-estratriene-4,17-di one. We found that care needed to be taken during the isolation of the dA adducts in particular, as any exposure to acidic environments caused hydrolysis of the sugar moiety leaving alkylated adenine. In mixtures of the deoxynucleosides treated with 4-OHEN, reaction occurred primarily with dG followed by dC and dA. With DNA significant apurinic sites were produced as 4-OHEN-adenine adducts were detected in the ethanol wash prior to hydrolysis. When the DNA was hydrolyzed to deoxynucleosides and analyzed by electrospray mass spectrometry, only one isomer of 4-OHEN-dG and one isomer of 4-OHEN-dC were observed. Our data suggest that several different types of DNA lesions could be expected from 4-OHEN including apurinic sites and bulky stable adducts, in addition to the published oxidized damage to DNA caused by 4-OHEN. The production of these semiquinone radical-derived DNA adducts could play a role in the carcinogenic effects of Premarin estrogens.

Alkylation↗
PubMed1998

[Retrograde partial hepatectomy: report of 11 patients].

OBJECTIVE: To study a new approach to hepatectomy for liver tumors resected difficulty by typical method. METHOD: The operative order is retrograde as compared with typical hepatectomy, namely, transection of the liver is performed first, isolating adhesions between the tumor and the diaphragm or partial invaded phrenectomy is performed second, and then after cutting corresponding ligaments, liver tumor is removed. If the surrounding organs were invaded or adhered by tumor too tightly to be separated. They were resected with the tumor. RESULT: The approach was used in 11 patients with malignant tumors of liver from June 1994 to January 1996. Operation time was 192 min (150 - 250 min) and estimated blood loss during operation was 1460 ml (800 - 4, 200 ml). No operative mortality was found and all of the patients recovered uneventfully. CONCLUSION: The retrograde partial hepatectomy is a good method for resection of liver tumors resected difficulty by typical hepatectomy.

Adult↗
PubMed1998

Metabolism of lipoproteins containing apolipoprotein B in hepatic lipase-deficient mice.

Mice lacking hepatic lipase have been reported to express mild hyperlipidemia characterized by increased concentrations of large high density lipoproteins, but normal concentrations of lipoproteins containing apolipoprotein B. Whereas hepatic lipase has been implicated in the clearance and processing of chylomicron remnants in rats, no such defect was found in these mice. We have further characterized the abnormal lipoprotein phenotype in young hepatic lipase-deficient mice and have found more pronounced elevations of high density lipoproteins associated in particular with a 5-fold increase in plasma concentrations of apolipoprotein E. In addition, there was a reduction in the concentration of low density lipoproteins containing apolipoprotein B-100 and B-48 relative to precursor lipoproteins of lower density and a pronounced deficiency of apolipoprotein B-containing low density lipoproteins with density exceeding 1.029 g/mL. Conversion of radiolabeled rabbit intermediate density lipoproteins to low density lipoproteins was reduced by 6-fold as compared with wild-type mice. Although clearance of cholesteryl ester-labeled chylomicrons from the blood was unimpaired in the deficient mice, that of chylomicron remnants was reduced. Furthermore, endocytosis of chylomicron cholesteryl esters into liver cells occurred more rapidly than in wild-type mice. The unimpaired hepatic clearance of injected chylomicron particles in hepatic lipase-deficient mice may be the result of greater acquisition of apoE from high density lipoproteins during remnant formation. These studies thus demonstrate a critical role for mouse hepatic lipase in the formation of small, dense low density lipoproteins, as well as participation in the normal clearance and processing of chylomicron remnants.

Animals↗
PubMed1997

Familial aggregation of oesophageal cancer in a high incidence area in China.

BACKGROUND: The high incidence of oesophageal cancer in northern China is attributed predominantly to environmental factors. The role of genetic factors has not been extensively studied. METHODS: Our aim was to study familial aggregation of oesophageal cancer in pedigrees from a defined population base in a high incidence area in China and to quantify the risk associated with different first degree relatives using different analytical approaches. Detailed data on family members of three successive generations and the occurrence of oesophageal and other cancers in family members were collected from a population-based series of 244 oesophageal cancer cases which occurred between 1987 and mid-1992 in Huixian County, Henan. RESULTS: Compared to expected rates, the standardized mortality ratio (SMR) of oesophageal cancer among first degree relatives of oesophageal cancer patients was 2.4 (2.2 in male and 2.7 in female relatives). The corresponding SMR for first and second degree relatives were 1.6 and 2.2. The null hypothesis of 'no familial aggregation' was rejected using Tarone's one-sided score test for binomial distributions indicating some evidence for clustering within families. To account for variance due to between-pairs correlation and family and/or individual specific variables, we fitted a series of regression models using a Generalized Estimation Equations (GEE) approach. The pairwise odds ratios were 2.3 for parent-parent, 1.9 for sib-parent and 1.1 for sib-sib, adjusted for sex, age and sex of index case. DISCUSSION: The existence of familial aggregation of oesophageal cancer in the study population was confirmed using different analyses and a two- to threefold increased risk was found for first degree relatives. The clear association of disease between parent and sib provides some indication of a genetic component. The pairwise association between parents but not between sibs suggests that environmental factors have a stronger action after childhood.

Aged↗
PubMed1997

[The structural changes of cortical bone beneath plate after rigid platefixation and removal].

We investigated the structural changes of bone under the plate after plate fixation and removal. Twenty-four New Zealand white rabbits were plated on their intact left tibiae with stainless steel plates and 4 animals served as controls. The plates were removed 2 months after implantation in 20 plated animals, of which, 4 were sacrificed immediately after plate removal and the other were killed in successive groups of 4 each at 1, 2, 3 and 4 months after plate removal respectively. The remaining 4 plated animals were killed at 6 months after implantation. Bone samples were harvested and prepared for scanning microscopic observation. Internal fixation with a rigid plate may lead not only to osteopenia of the cortex under the plate, but also to disorganization of the cortex, in which the mineral column and collagen fibers were oriented in a randomized pattern. The regional osteoporosis could recover gradually after removal of the rigid plate. However, the restoration of normal bone structure occurred later than that of the bone mass. Delayed restoration of bone structure might be one of the potential causes of refracture of the plated bone.

Animals↗
PubMed1997

[The expression of mdm2 gene related to the invasiveness of human hepatocellular carcinoma].

OBJECTIVE: mdm2 gene was used as an index to study the molecular mechanism related to the invasiveness of human hepatocellular carcinoma (HCC). METHODS: The expression of mdm2 gene in 34 HCC samples and 19 paratumor liver tissues and the relationship between the expression of mdm2 gene and invasiveness of HCC were studied using reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The expression level of mdm2 gene (x +/- Sx) in HCC samples was higher than that in paratumor liver tissues (50.18% +/- 5.24% vs. 27.70% +/- 7.43%, P < 0.05). The expression level of mdm2 gene in HCC samples with invasiveness was higher than that in HCC samples without invasiveness (59.09% +/- 7.28% Vs. 37.87% +/- 6.37%, P < 0.05). However, significant difference in expression of mdm2 gene was not found between small and large HCC as well as between HCC with and without capsule. CONCLUSION: The expression of mdm2 gene was related to the invasiveness of HCC.

Carcinoma, Hepatocellular↗
PubMed1997

[Contrast on therapeutic results of intraocular lens implantation in diabetics and non-diabetics].

PURPOSE: To observe the results of intraocular lens implantation in diabetics who suffered from cataract. METHODS: 30 cases (37 eyes) of diabetics with cataract and 174 cases (197 eyes) of non-diabetics with senile cataract were performed with intraocular lens implantation. The postoperative follow-up was from 2 to 18 months. RESULTS: The statistics of the visual acuity in two groups had no difference. The primary factor that effected visual acuity was original retinopathy. Postoperative complications of diabetics group, such as anterior chamber fibrinous exudate, pigment diffusion, were much serious than those of non-diabetic group. But if strong effective hormones were locally administrated, inflammation was absorbed. CONCLUSION: The therapeutic results of the diabetics with no or only minor retinopathy were similar with those of non-diabetics.

Aged↗
PubMed1997

[Minor Bupleurum decoction in the treatment of viral myocarditis models].

A myocarditis model of Balb/c mice established by means of coxsackie virus type B3 was treated with the Minor Bupleurum Decoction. The results indicate that the decoction can regulate T lymphocyte subsets, influence anti-cardiac antibody production, help the organism to get clear of viruses, and thus plays an important role in treating viral myocarditis.

Animals↗
PubMed1997

[The determination of olaquindox in feeds by HPLC].

A liquid chromatographic procedure for the determination of olaquindox in feeds is described. Chromatography was performed on a PC8-10/S2504 (4.0 mm i.d. x 250 mm, 10 microm, Shimadzu Co.) column at 30 degrees C by using a mobile phase of methanol:water (20:80, V/V ) with a flow rate of 0.8 mL/min and UV detection at 260 nm. Acetanilide was used as internal standard. Olaquindox was extracted with dimethylformamide (DMF) from the feeds. The average recoveries of olaquindox were 98.58%-101.63% and the relative standard deviations were 2.67%-4.25%. The method is simple, rapid, reliable and inexpensive.

Animal Feed↗
PubMed1997

Acceptance, efficacy, and side effects of Norplant implants in four counties in north China.

This report attempts to present a comprehensive analysis of the acceptability, side effects, and efficacy of Norplant as used in rural areas, based on a field experiment conducted in four counties in Hebei and Shandong Provinces, China. The initial acceptance of Norplant was relatively high but waned after the first year in three of the four counties. Compared with clinical trials, the current study shows a lower prevalence but similar patterns of side effects. The pregnancy rate during the first two years of use is similar to that found in large-scale clinical trials conducted in China, but discontinuation due to other reasons is lower. A three-level logistic regression analysis shows significant variation in the probability of discontinuation due to side effects across counties. It also indicates an increase in the conditional probability of discontinuation with the duration of use. Whereas introducing Norplant and achieving a very low failure rate and high continuation rate in rural areas is feasible under diverse socioeconomic conditions, the results vary significantly across different areas. Particular attention should be paid to the local factors that may affect results.

Adult↗
PubMed1996

Abnormal regulation of the LDL-R and HMG CoA reductase genes in subjects with familial hypercholesterolemia with the "French Canadian mutation".

Familial hypercholesterolemia (FH) is seen with high frequency in the province of Québec, Canada. A large deletion (> 10 kb) of the 5'-end of the low density lipoprotein receptor (LDL-R) gene is the major mutation of the LDL-R in FH subjects in Québec (approximately 60% of FH subjects). No mRNA is produced from the allele bearing the mutation, and cellular cholesterol obtained by receptor-mediated endocytosis is under the control of the non-deletion allele. We have previously reported that some patients with the 10-kb deletion (approximately 9%) fail to respond to the hydroxymethylglutaryl coenzyme A reductase (HMG CoA reductase) inhibitor class of medications. We studied mRNA levels of the LDL-R and HMG CoA reductase genes in response to the HMG CoA reductase inhibitor lovastatin in a time- and dose-dependent fashion in cultured human skin fibroblasts and we devised an in vitro model to study the response to drug therapy in subjects with FH. We determined mRNA levels by RNase protection assay in skin fibroblasts obtained from controls (n = 3) and FH subjects with the > 10-kb deletion (responders, n = 3; non responders, n = 3; to drug therapy). We measured 125I-LDL binding on skin fibroblasts grown in the presence of lipoprotein-deficient serum with or without 1 microM lovastatin, using 10 micrograms/mL of 125I-LDL protein. Control subjects exhibited coordinate regulation of the LDL-R and HMG CoA reductase genes in response to lovastatin, 0.1-25 microM, for 0-24 h. Correlation coefficients between mRNA levels of both genes were > 0.9 in controls and FH subjects. However, by linear regression analysis, the corresponding slopes for the correlation between both genes were 0.98 (controls), 3.36 and 3.63 (FH responders and non-responders), indicating a pattern of dissociated but still coordinate regulation in FH subjects. The magnitude of increase of mRNA levels of the LDL-R gene was approximately five-fold over LPDS in controls, two-fold in FH responders and two-fold in non-responders. Binding studies using 125I-LDL reveal that a control subject and all responders had a 2-2.5-fold increase in binding to cell surface receptors but two out of three FH non-responders showed no increase in binding in response to 1 microM lovastatin. The LDL-R and HMG CoA reductase genes are expressed in coordinate regulation in fibroblasts from subjects with FH due to the > 10-kb deletion, but with a proportionately greater up-regulation of the HMG CoA reductase gene. Some subjects, with FH caused by the > 10-kb deletion of the LDL-R gene, who fail to respond to HMG CoA reductase inhibitors have abnormal LDL receptor binding activity at the cell surface in response to lovastatin in vitro.

Anticholesteremic Agents↗
PubMed1995

[Fecundify after treatment of tubal pregnancy].

UNLABELLED: This study is a follow-up analysis of 103 patients who desired to preserve their fertile ability after treatment of tubal pregnancy. Among the 103 cases, 58 were treated by unilateral salpingectomy, 15 by salpingostomy and 30 by drug conservative therapy. RESULTS: 67 cases had intrauterine pregnancy and 9 cases repeated ectopic pregnancy. The intrauterine pregnancy rate of the surgical group (71.2%) was higher than that of the nonsurgical group (50.0%). And the pregnancy rate of salpingostomy group (86.7%) was higher than that of salpingectomy group (67.2%). No repeated ectopic pregnancy occurred in the salpingostomy group. After three months of treatment, 45 cases were randomly sampled for tubal patency test. Bilateral tubal patency rate in salpingostomy group was 93.3% and in drug treatment group was 20.0%. These results indicated that tubal patency is an essential factor for normal pregnancy. Prevention of post-operative adhesion and treatment of pelvic inflammatory disease are important for increasing intrauterine pregnancy rate and decreasing repeated ectopic pregnancy rate.

Fallopian Tube Patency Tests↗
PubMed1995

An overview of the CERC ARTEMIS project.

The basic premise of this effort is that health care can be made more effective and affordable by applying modern computer technology to improve collaboration among diverse and distributed health care providers. Information sharing, communication, and coordination are basic elements of any collaborative endeavor. In the health care domain, collaboration is characterized by cooperative activities by health care providers to deliver total and real-time care for their patients. Communication between providers and managed access to distributed patient records should enable health care providers to make informed decisions about their patients in a timely manner. With an effective medical information infrastructure in place, a patient will be able to visit any health care provider with access to the network, and the provider will be able to use relevant information from even the last episode of care in the patient record. Such a patient-centered perspective is in keeping with the real mission of health care providers. Today, an easy-to-use, integrated health care network is not in place in any community, even though current technology makes such a network possible. Large health care systems have deployed partial and disparate systems that address different elements of collaboration. But these islands of automation have not been integrated to facilitate cooperation among health care providers in large communities or nationally. CERC and its team members at Valley Health Systems, Inc., St. Marys Hospital and Cabell Huntington Hospital form a consortium committed to improving collaboration among the diverse and distributed providers in the health care arena. As the first contract recipient of the multi-agency High Performance Computing and Communications (HPCC) Initiative, this team of computer system developers, practicing rural physicians, community care groups, health care researchers, and tertiary care providers are using research prototypes and commercial off-the-shelf technologies to develop an open collaboration environment for the health care domain. This environment is called ARTEMIS--Advanced Research TEstbed for Medical InformaticS.

Computer Communication Networks↗
PubMed1995

[A comparative study of effects on bone healing and remodelling between embracing fixator and bone].

The authors made their own design of sawteeth-arm embracing internal fixator (SEIF) with NiTi shape memory alloy and used for fractured femoral shaft of dogs in comparison with 316L stainless steel plate-screw system. A transverse osteotomy on both sides of femoral diaphyses was performed in 15 adult dogs. One side was plated with bone plate and the other with SEIF. Five animals in each group were killed at 4, 8, 12 weeks after operation and observed under roentgen rays examination, light microscopy and transmission electron microscopy. The results showed that the fracture healing and the course of callus remodelling were similar in these two groups, but the cortical bone remodelling underneath the fixater near osteotomized area was significantly different. Eight-week post-implantation, osteocytes entered into degenerative phase were observed in cortical bone underneath SEIF, and 12-week after operation, the numbers of degenerative osteocytes increased remarkably. While in the case of bone plate, 4-week post-implantation, osteocytes entered into degenerative phase, and 8-week afterwards autolysis occurred in most of the degenerative osteocyles. In other words, the changes of osteocytes phase in bone plate side appeared earlier and more vigorous than that in the SEIF side. The authors are of the opinion that the elastic modulus of NiTi shape memory alloy is lower, the stress-shielding effect in the bone underneath SEIF is less, the axial compression stress of fracture line is kept larger and the contact of SEIF with the bone is not so close that is beneficial to the recovery of blood supply and bone remodelling.

Alloys↗
PubMed1995

[A morphological study of degenerative mechanism of articular cartilage by abnormal high stress].

The articular cartilage from the right knee of 87 rats whose left calcaneal tendons had been transected was examined under transmission and scanning electron microscopes, and light microscope. Morphological observation showed a few small focal areas of cartilage surface disruption, pit and collagen fibrillation at 2 weeks after operation. After 1 month, many clusters of chondrocytes could be found, showing hyperactive synthetic and secretary activity. The cartilage degenerated progressively. The initial lesion in high stress side was at the matrix of cartilage, the collagen network was disrupted, then proteoglycan become degraded. The microenvironment of chondrocytes was changed with degradation of matrix. The chondrocytes became degenerative. The degeneration of chondrocytes influence the matrix again. A vicious cycle was thus formed. At the early stage of the degeneration of the cartilage induced by high-stress, som chondrocytes proliferate and have hyperactive synthetic and secretive functional activity. But soon, most of the chondrocytes degenerate. That is because of the chondrocytes have got repaired in response to initial matrix lesion and the normal microenvironment had degraded with aggravation of matrix lesion. These chondrocytes again became degenerative quickly.

Animals↗
PubMed1995

[Clinical application of silica ball implant enclosed by an autologous reversal sclera in patients with enucleation].

PURPOSE: To observe the effects of improved silica ball implantation enclosed by autologous reversal sclera. METHODS: After the enucleation of eye balls, we reversed, cleared the autologous sclera, enclosed the silica ball and implanted it in the operative eye. RESULTS: 30 cases with enucleation were implanted the prosthetic eyes. The follow-up period was 6 months to 3 years. The prosthetic eyes had the motility of 10 degrees to 25 degrees and the empty socket syndrome was effectively prevented. CONCLUSION: The sargical method can overcome the defect that prosthetic eyes cannot rotate after being implanted and has got satisfactory cosmetic effects.

Adolescent↗