Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 253 records · Page 14Linked to original sources

PubMed2001

Influence of body fat distribution on oxygen uptake and pulmonary performance in morbidly obese females during exercise.

OBJECTIVE: The aim of this study was to determine the effects of fat distribution on aerobic and ventilatory response to exercise testing in morbidly obese (MO) females. METHODOLOGY: The study population consisted of 164 MO females, 55% (n = 90) with upper body or abdominal adiposity (UBD), as defined by waist-hip circumference ratio (WHR) > or = 0.80, and 45% (n = 74) with lower body fat distribution (LBD) (WHR < 0.80). An incremental exercise testing on cycle ergometer was performed to determine the effect of exercise on oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), tidal volume (VT), respiratory rate (fb) and heart rate (HR). RESULTS: Upper body adiposity individuals had significantly higher VO2 and VCO2 than LBD subjects (P < 0.05) from 0 watt (W) of pedalling up to their anaerobic threshold (AT) and maximal exercise. VE was significantly higher in UBD subjects compared with LBD subjects, from 20 W during exercise up to AT and peak work levels (P < 0.05). Upper body adiposity group also had a significantly higher fb than the LBD group at rest, after each workload and at AT and peak exercise work rates (P < 0.05). VT was lower in UBD subjects at free pedalling and up to AT and peak workload with significant difference at 60 and 80 W (P < 0.05). The anaerobic threshold, expressed as work rate, was significantly lower in the UBD subjects (P < 0.05) and peak workload achieved did not differ significantly between the two groups. CONCLUSIONS: Upper body adiposity subjects had higher oxygen requirement, more rapid and shallow breathing, higher ventilatory demand, but lower anaerobic threshold than the LBD individuals during progressive exercise. It suggests that the cardiopulmonary endurance to exercise in MO patients with upper body fat distribution is lower than in those with lower body fat distribution.

Adipose Tissue↗

PubMed2001

Prognostic significance of platelet-derived endothelial cell growth factor/thymidine phosphorylase expression in stage pT1 G3 bladder cancer.

BACKGROUND: The management of patients with pT1 G3 bladder cancer remains controversial because of the high incidence of recurrence with muscle invasion. Thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and has angiogenic activity. The aim of this study was to determine whether the expression of PD-ECGF/dThdPase in bladder cancer tissue was associated with tumor progression and recurrence in patients with pT1 G3 bladder cancer. METHODS: Fifteen patients who were pathologically diagnosed as having pT1 G3 transitional cell carcinoma of the bladder were treated with transurethral resection. Sections of paraffin-embedded bladder tissue were immunohistochemically stained with either mAb654-1, a monoclonal antibody against human PD-ECGF or anti-CD34 monoclonal antibody, respectively. When more than 10% of tumor cells were positively stained with mAb654-1, this section was defined as positive in this study. RESULTS: Eight of 15 sections from patients with pT1 G3 bladder cancer (53%) were positive with PD-ECGF/dThdPase. During follow up, patients in the negative group had no disease progression and only two patients had local recurrence. In contrast, seven of eight positives had recurrence (P < 0.05) and progression was also observed in four recurrent patients. However, there was no statistical relationship between PD-ECGF and CD34 expression in any of the patients. CONCLUSION: The expression of PD-ECGF/dThdPase appears to be an important prognostic factor of pT1 G3 bladder cancer and did not show any significant relationship between PD-ECGF/dThdPase expression and vascular density.

Aged↗

PubMed2001

Interleukin-10 inhibits ischemic and cisplatin-induced acute renal injury.

BACKGROUND: Acute renal failure (ARF) is caused by ischemic and nephrotoxic insults acting alone or in combination. Anti-inflammatory agents have been shown to decrease renal ischemia-reperfusion and cisplatin-induced injury and leukocyte infiltration. Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that inhibits inflammatory and cytotoxic pathways implicated in acute renal injury. Therefore, we sought to determine if IL-10 inhibits acute renal injury. METHODS: The effects of IL-10 were studied in mice following cisplatin administration and bilateral renal ischemia-reperfusion, in a rat model of renal transplantation, and in cultured mouse cortical tubule cells. RESULTS: IL-10 significantly decreased renal injury following cisplatin administration and following renal ischemia/reperfusion. Delay of IL-10 treatment for one hour after cisplatin also significantly inhibited renal damage. IL-10 and alpha-melanocyte stimulating hormone (alpha-MSH) increased recovery following transplantation of a kidney subjected to warm ischemia. To explore the mechanism of action of IL-10, its effects were measured on mediators of leukocyte trafficking and inducible nitric oxide synthase (NOS-II). IL-10 inhibited cisplatin and ischemia-induced increases in mRNA for tumor necrosis factor-alpha (TNF-alpha), intercellular adhesion molecule-1 (ICAM-1), and NOS-II. IL-10 also inhibited staining for markers of apoptosis and cell cycle activity following cisplatin administration, and nitric oxide production in cultured mouse cortical tubules. CONCLUSIONS: IL-10 protects against renal ischemic and cisplatin-induced injury. IL-10 may act, in part, by inhibiting the maladaptive activation of genes that cause leukocyte activation and adhesion, and induction of iNOS.

Animals↗

PubMed2001

Cardiovascular disease in end-stage renal disease patients.

This study evaluates risk factor monitoring in end-stage renal disease (ESRD) patients with cardiovascular disease. Death rates from cardiovascular disease in ESRD patients are 20 to 40 times higher than in the general population, and 72% of ESRD patients with an acute myocardial infarction (AMI) are dead within 2 years of follow-up. Patients who have sustained an AMI rarely receive definitive testing to assess coronary circulation, and cardiac catheterization rates and revascularization rates are low, even after the high-risk event of an AMI. Risk factor intervention to treat lipid disorders in the ESRD population has received little attention, with the USRDS reporting that in 1998, 58% of dialysis and 64% of transplant patients had no lipid monitoring performed within a year. Of those tested, only 33% of dialysis and 27% of transplant patients had two or more tests within 1 year. Glycemic control monitoring in the form of HbA1c, recommended for diabetes management, is also underutilized in ESRD patients, with fewer than half receiving a single test within 1 year and only 10% receiving three or more tests. This raises concerns that diabetic glycemic control monitoring may be suboptimal in the ESRD population. The use of diabetic eye examinations and diabetic glucose monitoring is also low, as are influenza vaccination rates. These data suggest that the clinical care of cardiovascular disease in the ESRD patients needs more attention.

Adult↗

PubMed2001

Three-point gait crutch walking: variability in ground reaction force during weight bearing.

OBJECTIVE: To investigate variability in ground reaction force (GRF) and kinematics on both sides during 3-point partial weight-bearing (PWB) crutch walking. DESIGN: Within-subject comparisons of kinematic and kinetic data collected at different levels of 3-point crutch walking: 10%, 50%, and 90% PWB at comfortable speeds. SETTING: An applied biomechanics lab in a university setting. An applied biomechanics lab in a university setting. PARTICIPANTS: Twelve healthy college students (9 women, 3 men). MAIN OUTCOME MEASURES: Spatial and temporal variables, major peak kinematic data, and peak GRFs from force platforms during the gait cycle. RESULTS: Large variations were found in replicating the target levels of PWB, particularly at 10% and 90% PWB. Subjects had a shorter stance phase and longer swing phase during the crutch walking gait cycle. Velocity significantly decreased (p =.006) because of decreased cadence (p =.002). Slightly greater hip abduction and external rotation on the noninvolved side and slightly less hip adduction and internal rotation on the involved side indicated that the center of gravity shifted slightly from the involved side toward the noninvolved side. There was no increase in vertical GRF, and there was a relatively constant loading pattern on the noninvolved side. CONCLUSIONS: Subjects have difficulty replicating a prescribed weight-bearing restriction. A shift of the center of gravity toward the noninvolved side may reduce the weight distribution on the involved side.

Adult↗

PubMed2001

Familial intrahepatic cholestasis 1: studies of localization and function.

Mutations in the FIC1 gene constitute the molecular defect in familial intrahepatic cholestasis I (Fic1 [Byler's disease]) and benign recurrent intrahepatic cholestasis. This report describes the localization of Fic1 in rat liver and intestine, as well as biochemical and transfection studies that support its function as an energy-dependent aminophospholipid translocase. Immunocytochemistry of rat liver and immunoblotting of membrane fractions localized Fic1 to the canalicular, but not basolateral, plasma membrane domain. In the small intestine, Fic1 was localized to the apical membrane of epithelial cells. The distribution of Fic1 in liver plasma membrane fractions from control and taurocholate-treated rats correlated positively with adenosine triphosphate (ATP)-dependent aminophospholipid (phosphatidyl-serine) translocase activity. In canalicular membrane vesicles, translocase activity had an initial velocity of 3.3 nmol phosphatidylserine (PS) translocated per milligram of protein per minute and a K(m) (ATP) = 1.2 mmol/L; was inhibited by vanadate, N-ethylmaleimide, sodium azide, and calcium; and was unidirectional (i.e., from the outer to the inner canalicular plasma membrane leaflet). Transient transfection of CHOK1 cells with FIC1 cDNA resulted in appearance of FIC1 in membrane preparations and energy-dependent PS translocation in cells. These studies indicate that FIC1 is a canalicular P-type ATPase that participates in maintaining the distribution of aminophospholipids between the inner and outer leaflets of the plasma membrane. How this process produces cholestasis is under study.

Adenosine Triphosphatases↗

PubMed2001

Bending of the distraction site during mandibular distraction osteogenesis in the rabbit: a model for studying segment control and side effects.

PURPOSE: The purpose of this investigation was to develop an animal model for studying and correcting mandibular distraction side effects. MATERIALS AND METHODS: Twenty-nine rabbits underwent bilateral mandibular distraction. Bending of the mandible was accomplished by offsetting a linear distraction by 35 degrees from the occlusal plane (4 screws per distractor), rotating the anterior segment inferiorly (2 screws per distractor), and removing a 3- or 6-mm wedge of the distraction site. The amount of bite opening varied according to the surgical design. Direct measurements, radiographs, and histology samples were compared. RESULTS: Linear distraction produced a 4-mm anterior open bite and a Class III malocclusion after 2 weeks of distraction. Segmental rotation produced an 8-mm anterior open bite without complications. Removal of a wedge initiated rotation of the anterior segment. A large wedge (6 mm) produced fibrous union in the distraction site. The amount of bite opening or closure depended on the number of surgical screws and position of the distractor. Serial histologic sections showed bone formation at the rotated, triangular distraction site. CONCLUSION: Bite opening or closure can occur from loss of segment control or by altering surgical design. This information is needed to counter unwanted side effects or to plan segment rotations.

Analysis of Variance↗

PubMed2001

Transparent morphology of the thoracoabdominal wall.

The transverse rectus abdominis myocutaneous (TRAM) flap has become the gold standard for autologous breast reconstruction in the last decade. The deep inferior epigastric perforator (DIEP) flap is a refinement of the conventional myocutaneous flap, which is based on anatomic studies of the abdominal wall. These authors have performed a transparent morphologic study of the abdominothoracic wall, in order to visualize the vessel architecture and relationships. The methodology of specimen processing, the anatomic findings, and modifications of surgical incisions are illustrated and discussed.

Abdominal Muscles↗

PubMed2001

Childhood vaccination against varicella: persistence of antibody, duration of protection, and vaccine efficacy.

OBJECTIVE: To document the duration of protection afforded by Oka/Merck varicella vaccine over a 7-year period. STUDY DESIGN: The subjects were healthy children 1 to 12 years of age originally enrolled in clinical studies to evaluate the primary immune response to varicella vaccine 6 weeks after vaccination. Each was monitored for antibody persistence, breakthrough infection, and household exposure to varicella to produce estimates of vaccine efficacy. RESULTS: The 6-year cumulative varicella antibody persistence rate was 99.5% (95% CI: 98.9%, 100.0%). The annual breakthrough rate through 7 years ranged from 0.2% to 2.3% per year; the estimated cumulative event rate was 6.5%. Comparison of the observed average annual breakthrough rate with the age-adjusted expected annual incidence rate of varicella in unvaccinated children corresponded to an estimated vaccine efficacy of 93.8% to 94.6%. Eighty vaccinated children were exposed to varicella in the household, resulting in 8 (10%) cases of infection. When compared with the historical attack rate of 86.8% in unvaccinated susceptible persons exposed to varicella in the household, this yields an estimated vaccine efficacy of 88.5% (95% CI: 80.9%, 96.1%). Varicella cases in vaccinated children generally were mild. CONCLUSION: The live attenuated varicella vaccine is highly effective in inducing persistent immunity and long-term protection against breakthrough varicella infection.

Age Distribution↗

PubMed2001

Screening for CRX gene mutations in Chinese patients with Leber congenital amaurosis and mutational phenotype.

PURPOSE: To screen for possible disease-causing mutations in the CRX gene in Chinese patients with Leber congenital amaurosis (LCA) and to enrich the understanding of its mutational phenotype. METHODS: Genomic DNA was collected from 27 patients with LCA. The coding sequences of the CRX gene were analyzed using the PCR-heteroduplex-SSCP method. Mutations were confirmed by DNA sequencing. RESULTS: We identified two heterozygous variations in the CRX gene in two patients with LCA. One was a deletion (GCC-->-CC, A181D1bp) leading to a frameshift and protein truncation. This mutation was present in a patient with LCA, but not in his healthy parents. The ocular manifestations of this A181Delta1bp mutation are described. An intronic variation (IVS1-13G-->C) was found in a patient with LCA as well as in his healthy father. CONCLUSION: A heterozygous A181D1bp mutation in the CRX gene caused an LCA phenotype in a Chinese patient.

Asian People↗

PubMed2001

Formation and evolution of haloacetic acids in drinking water of Beijing City.

The formation and evolution of haloacetic acids (HAAs) in drinking water were examined in five water treatment plants in Beijing City, China. It was found that HAAs in water increased due to prechlorination and postchlorination. The conventional treatment processes removed the HAAs in less than 20%. By comparison, activated carbon bed removed 49-86% of HAAs and was considered to be an effective treatment unit for HAAs removal. The HAAs concentration in distribution system was associated with water sources, especially the total organic carbon in raw water, while its fluctuation appeared small.

Acetates↗

PubMed2001

Characterization of nasal spray pumps and deposition pattern in a replica of the human nasal airway.

Deposition patterns are described of a nasal spray formulation for a novel rhinovirus protease inhibitor. These patterns, which were generated from different nasal spray pumps, were characterized using a multisectional nasal airway model. A human nasal replica was made from an in vivo magnetic resonance imaging (MRI) scan of an adult male human. The nasal replica consisted of 77 acrylic plastic sections, 1.5-mm thick. Our data showed that the aerosols were deposited mainly in the anterior and turbinate regions with little passing beyond the nasopharyngeal region. Detailed deposition information from the turbinate region indicated that deposition was high toward the anterior portion where most deposition was concentrated on the inferior meatus. Spray droplets were also deposited in spots of the middle and posterior portions of the turbinate region, and this nonuniform deposition pattern may be correlated with the flow pattern. The spray angle and droplet size of the nasal spray were found to be important in influencing the deposition pattern in the nasal airway. The droplet size was determined by a laser-diffraction technique and the spray angle by high-speed photography. Larger droplets and a wider spray angle increased deposition in the anterior region of the nasal airway, which prevented more material from depositing in the turbinate region.

Administration, Inhalation↗

PubMed2001

Drug delivery performance of the mometasone furoate dry powder inhaler.

The mometasone furoate dry powder inhaler (MF-DPI) is a multiple-dose, breath-actuated inhaler that uses agglomerates of micronized MF and lactose. In vitro analyses evaluated dose uniformity, variability, and particle size distribution of the MF-DPI. Tests of first, middle, and end doses from 10 inhalers each of the 200-microg MF/inhalation and 400-microg MF/inhalation dose sizes found that delivered doses (doses emitted from the inhaler) ranged from 91% to 112% of claimed doses for all tested DPIs. The mean MF doses delivered at 28.3 L/min were 100% and 94% of the doses delivered at 60 L/min for the 200-microg and 400-microg dose sizes, respectively; the relative standard deviation of doses was < or = 6.1% within this range of inhalation rates. At a flow rate of 60 L/min, the mean delivered doses, compared to claimed doses for inspiration times of 1-3 sec, were 102-104% for the 200-microg dose size and 98.8-102% for the 400-microg dose size. The mean cumulative fraction of dose delivered at 60 L/min for 2 sec which consisted of particles of <6.5 microm in diameter was 39.9% (+/-2.5 SD; n = 9) for the 200-microg dose size and 35.6% (+/-3.4 SD; n = 9) for the 400-microg dose size. All MF-DPI inhalers tested were well within U.S. and European compendial standards and regulatory guidelines for dose uniformity. An appropriate and reproducible fraction of the delivered dose was within the optimal particle size range for therapeutic effectiveness.

Administration, Inhalation↗

PubMed2001

GPx-1 gene delivery modulates NFkappaB activation following diverse environmental injuries through a specific subunit of the IKK complex.

Numerous environmental stimuli alter cell functions by the induction of intracellular reactive oxygen species, such as superoxide and hydrogen peroxide (H2O2). These redox alterations can change the activity of kinases and phosphatases responsible for controlling intracellular signal transduction cascades important in determining how cells react to their environment. One such well known pathway includes nuclear factor-kappaB (NFkappaB); however, the exact redox-sensitive factors important in controlling H2O2-mediated activation of NFkappaB remain unclear. In the present study, we have investigated how intracellular clearance of H2O2, using a recombinant adenovirus expressing glutathione peroxidase-1 (GPx-1), modulates NFkappaB activation following UV irradiation, tumor necrosis factor-alpha, or H2O2 treatment of MCF-7 cells. Findings from these studies demonstrate that GPx-1 overexpression can down-regulate NFkappaB DNA binding, and transcriptional activation of an NFkappaB-dependent luciferase reporter, to varying extents following these environmental stimuli. Studies using dominant negative adenoviral vectors expressing IKKalpha(KM) and IKKbeta(KA) suggest that GPx-1-mediated H2O2 clearance appears to preferentially inhibit the activity of IKKalpha, but not IKKbeta. These studies demonstrate for the first time that redox regulation of NFkappaB activation by intracellular H2O2 may be specific for a unique subunit in the IKK complex. Such findings suggest that IKK kinases or IKK phosphatases may have unique redox-regulated components. These studies have shed mechanistic insight into the potential application of redox-modulating gene therapies aimed at altering NFkappaB activation following environmental injury.

Adenoviridae↗

PubMed2001

V-Ha-Ras overexpression induces superoxide production and alters levels of primary antioxidant enzymes.

Reactive oxygen species have been shown to play important roles in v-Ha-Ras mitogenic signaling. We hypothesized that v-Ha-Ras overexpression would induce superoxide production, and therefore modify expression of the primary antioxidant enzyme system. We have demonstrated that immortal rat kidney epithelial cells stably transduced with constitutively active v-Ha-ras produced significantly larger amounts of superoxide radical than wild-type or vector-transfected control cells. The levels of the primary antioxidant enzymes copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, and glutathione peroxidase were increased in the superoxide-overproducing cells. DNA-binding activities of the transcription factors activator protein-1, activator protein-2, and nuclear factor-kappaB were all enhanced in the superoxide-overproducing cells. These v-Ha-ras transduced cells also had a shortened cell doubling time and higher plating efficiency, and displayed greater constitutive levels of phosphorylated mitogen-activated protein kinases. These data demonstrate that v-Ha-Ras overexpression increases superoxide production and this apparently affects a wide variety of cell signaling and redox systems.

Animals↗

PubMed2001

Positional cloning of the mouse saccharin preference (Sac) locus.

Differences in sweetener intake among inbred strains of mice are partially determined by allelic variation of the saccharin preference (Sac) locus. Genetic and physical mapping limited a critical genomic interval containing Sac to a 194 kb DNA fragment. Sequencing and annotation of this region identified a gene (Tas1r3) encoding the third member of the T1R family of putative taste receptors, T1R3. Introgression by serial backcrossing of the 194 kb chromosomal fragment containing the Tas1r3 allele from the high-sweetener-preferring C57BL/6ByJ strain onto the genetic background of the low-sweetener-preferring 129P3/J strain rescued its low-sweetener-preference phenotype. Polymorphisms of Tas1r3 that are likely to have functional significance were identified using analysis of genomic sequences and sweetener-preference phenotypes of genealogically distant mouse strains. Tas1r3 has two common haplotypes, consisting of six single nucleotide polymorphisms: one haplotype was found in mouse strains with elevated sweetener preference and the other in strains relatively indifferent to sweeteners. This study provides compelling evidence that Tas1r3 is equivalent to the Sac locus and that the T1R3 receptor responds to sweeteners.

Alleles↗

PubMed2001

Polymorphism at the ribosomal DNA spacers and its relation to breeding structure of the widespread mushroom Schizophyllum commune.

The common split-gilled mushroom Schizophyllum commune is found throughout the world on woody substrates. This study addresses the dispersal and population structure of this fungal species by studying the phylogeny and evolutionary dynamics of ribosomal DNA (rDNA) spacer regions. Extensive sampling (n = 195) of sequences of the intergenic spacer region (IGS1) revealed a large number of unique haplotypes (n = 143). The phylogeny of these IGS1 sequences revealed strong geographic patterns and supported three evolutionarily distinct lineages within the global population. The same three geographic lineages were found in phylogenetic analysis of both other rDNA spacer regions (IGS2 and ITS). However, nested clade analysis of the IGS1 phylogeny suggested the population structure of S. commune has undergone recent changes, such as a long distance colonization of western North America from Europe as well as a recent range expansion in the Caribbean. Among all spacer regions, variation in length and nucleotide sequence was observed between but not within the tandem rDNA repeats (arrays). This pattern is consistent with strong within-array and weak among-array homogenizing forces. We present evidence for the suppression of recombination between rDNA arrays on homologous chromosomes that may account for this pattern of concerted evolution.

Base Sequence↗

PubMed2001

Kinetic properties of Streptococcus pneumoniae hyaluronate lyase.

Streptococcus pneumoniae hyaluronate lyase is a surface antigen of this bacterial pathogen, which causes significant mortality and morbidity in human populations worldwide. The primary function of this enzyme is the degradation of hyaluronan, a major component of the extracellular matrix of the tissues of practically all vertebrates. The enzyme uses a processive mode of action to degrade hyaluronan to a final product, an unsaturated disaccharide hyaluronan unit. This catalysis proceeds via a five-step proton acceptance and donation mechanism that includes substrate binding, catalysis, release of the disaccharide product, translocation of the remaining hyaluronan substrate, and proton exchange with microenvironment. Based on the analysis of the three-dimensional structure of the native enzyme and its complexes with hexasaccharide substrate and disaccharide product, several residues have been chosen for mutation studies. These mutated residues included the catalytic residues Asn349, His399, Tyr408, and residues responsible for substrate binding and translocation, Arg243 and Asn580. The comparison of the kinetic properties of the wild-type with the mutant enzymes allowed for the characterization of every mutant and the correlation of the kinetic properties of the enzyme with its structure. The comparison of the wild-type hyaluronate lyase with other polysaccharide-degrading enzymes, the hydrolases endonuclease and glucoamylase, shows striking similarity of K(m)s for all of these different enzymes.

Binding Sites↗