Biomedical subjects

W Shi

Publications and source records attributed to W Shi.

241 records · Page 14Linked to original sources

PubMedDate not supplied

Cadmium accumulation and effects on progesterone release by cultured human trophoblast cells.

This study was designed to examine the characteristics of cadmium bioaccumulation by human trophoblast cells in culture and the subsequent effect of cadmium exposure on progesterone production and syncytial formation. The accumulation of cadmium suggested a time- and dose-dependent relationship, although it was not significant. The rate of metal accumulation was similar in all cadmium-treated groups. After 72 h of continuous exposure to cadmium concentrations of 5, 10, and 20 microM, progesterone release was diminished to 69, 51, and 38% of control values (P < 0.05), respectively. When cells were exposed to cadmium from 72 to 96 h (after syncytial development), progesterone release exhibited the same pattern of decline in response to increasing cadmium concentrations. Histologic evaluation of whole mounts of trophoblast cells exposed to 20 microM CdCl2 for 96 h revealed that syncytial formation seemed to be uninhibited. The pattern of cadmium-accumulation by normal cultured human trophoblast cells suggests a time- and dose-relationship with a concomitant decrease in progesterone release that occurs without apparent inhibition of syncytial development.

Cadmium↗

PubMedDate not supplied

O2-Hb reaction kinetics and the Fåhraeus effect during stagnant, hypoxic, and anemic supply deficit.

We modified our previous computer model of O2 and CO2 transport in the cerebral microcirculation to include nonequilibrium O2-Hb kinetics and the Fåhraeus effect (reduced tube hematocrit in small microvessels). The model is a steady-state multicompartmental simulation which includes three arteriolar compartments, three venular compartments, and one capillary compartment. Three different types of oxygen deficits (stagnant, hypoxic, and anemic conditions) were simulated by respectively reducing blood flow, arterial O2 saturation, and systemic hematocrit to one half of normal. Microcirculatory distributions for PO2, PCO2, O2 saturation and deviations from equilibrium, and the O2 and CO2 fluxes for each compartment were predicted for the three O2 supply deficits. Differences were found for O2 extraction ratios and relative contributions of arteriolar, venular, and capillary gas fluxes for each type of deficit. The Fåhraeus effect and O2-Hb kinetics reduced O2 extraction in all cases and altered microcirculatory gas distributions depending on the specific type of O2 supply deficits. The modified model continues to predict that capillaries are the major site where gas exchange takes place, and demonstrates that the Fåhraeus effect and nonequilibrium O2-Hb kinetics are important mechanisms that should not be neglected in O2 and CO2 transport modeling. While this model provides useful insight regarding the influence of the Fahraeus effect and O2-Hb kinetics under steady state, the addition of a distributed and dynamic simulation should further elucidate the effects of the brain's heterogeneous properties and transient behavior.

Algorithms↗

PubMedDate not supplied

Partial characterization of bovine elastin gene; comparison with the gene for human elastin.

A 14 kilobase (kb) genomic clone of the gene for bovine elastin, containing exons 1 and 2, has been characterized. This clone extends about 6.5 kb in the 5' direction from the initiation codon and 978 nucleotides in the 3' direction from exon 2. The size of the first intron is about 6.4 kb. The sequence immediately 5' to the initiation codon is highly conserved between the genes for bovine and human elastins and contains a TATA box consensus sequence (ATAAA), CAAT, and Sp1 binding sites. Several putative AP-2 binding sites are also present. Comparative analysis of the sequences flanking the first exon in the genes for bovine and human elastins identified conserved sequences that may be regulatory control elements. A putative enhancer core sequence is present in the first intron of the genes for bovine and human elastins.

Animals↗

PubMedDate not supplied

Pap smears in women with endometrial carcinoma.

OBJECTIVE: To correlate Pap smear findings with the histology of endometrial carcinoma and stage of the disease. STUDY DESIGN: Between 1995 and 1998, 76 women with endometrial carcinoma, having had Pap smears done within two to three months of hysterectomy at Memorial Sloan-Kettering Cancer Center, formed the basis for this study. All Pap smears and histologic sections were reviewed. RESULTS: Thirty-four patients had normal Pap smears (45%), and 42 had abnormal ones (55%). The mean age of the two groups was 65.1 and 65.2 years, respectively. Histologic subtypes included 44 International Federation of Gynecology and Obstetrics (FIGO) grade 1 endometrioid adenocarcinoma (low grade) and 32 high grade carcinomas, including 19 FIGO grade 2 or 3 endometrioid adenocarcinomas, 5 papillary serous carcinomas (PSC), 2 clear cell carcinomas (CC), 1 adenosquamous carcinoma, 3 endometrioid adenocarcinomas mixed with PSC and 2 endometrioid adenocarcinomas mixed with CC. The proportions of patients with low and high grade tumors with abnormal Pap smears were 43% (19/44) and 72% (23/32), respectively (P=.01). The proportions of patients with abnormal Pap smears and no myometrial invasion, invasion of <50% and >50% myometrial thickness were 40% (8/20), 62% (26/42) and 57% (8/14), respectively (P =.27). Vascular invasion was identified in 56% (9/16) of patients with abnormal Pap smears and in 55% (33/60) of patients with normal ones (P = .93). The proportions of patients having abnormal Pap smears with stage I and stages II, III or IV disease were 48% (30/62) and 86% (12/14), respectively (P =.01). CONCLUSION: Although the Pap smear is not a sensitive screening test for endometrial cancer and a negative Pap smear does not rule it out, this study revealed that abnormal Pap smears are significantly associated with high grade of tumor and stage II-IV endometrial carcinoma. However, they are not associated with patient age, depth of myometrial invasion or vascular invasion.

Adenocarcinoma↗

PubMedDate not supplied

Peritoneal washings in endometrial carcinoma. A study of 298 patients with histopathologic correlation.

OBJECTIVE: To correlate findings of peritoneal washings in patients with endometrial carcinoma with histologic parameters. STUDY DESIGN: Between 1995 and 1998, 298 women with endometrial carcinoma were treated by hysterectomy with intraoperative peritoneal washings (PW) at Memorial Sloan-Kettering Cancer Center. All cytology and pathology slides were available for review. Pathologic parameters of hysterectomy specimens were evaluated and correlated with the findings of PW. RESULTS: Thirty-two patients (10.7%) had abnormal PW. Two hundred sixty-two had endometrioid adenocarcinoma; 26 of them had abnormal PW (10.0%). Thirty-six patients had other histologic subtypes (papillary serous carcinoma, clear cell carcinoma and adenosquamous carcinoma), and six of them had abnormal PW (16.7%). The incidence of abnormal PW in the two groups was not significantly different (P = .78). Among 26 patients with endometrioid adenocarcinoma and abnormal PW, there were 17 cases (9.9%) of International Federation of Gynecology and Obstetrics (FIGO) grade 1, 7 (12.7%) of grade 2 and 2 (5.7%) of grade 3 (P = .56). Ten cases (14.9%) had no myometrial invasion, 10 (7.0%) had myometrial invasion of < or = 50% of myometrial thickness, and 6 (11.5%) had invasion of > 50% of myometrial thickness (P = .18). Vascular invasion was present in 8 cases (14.8%) and absent from 17 (8.2%) (P = .14). Eighteen patients (7.6%) had stage I/II disease, and eight patients (30.8%) had stage III/IV disease (P = .001). Among 298 patients, cervicovaginal smears performed before surgery were available for review in 76. Five of the 7 patients (71.4%) with abnormal PW and 37 of the 69 patients (53.6%) with normal PW had abnormal Pap smears (P = .45). CONCLUSION: Abnormal PW did not correlate with histologic subtypes, FIGO grade, depth of myometrial invasion, vascular invasion or abnormal Pap smears. A significantly higher incidence of abnormal PW was associated with stage III/IV disease.

Adult↗

PubMedDate not supplied

Stepwise gradient elution of capillary electrochromatography in the analysis of environmental samples.

Two modes of stepwise gradient elution of capillary electrochromatography were developed for the analysis of environmental samples on both a laboratory-made and a commercial CE instrument. Using the laboratory-made apparatus, another mobile phase was dropped directly into the inlet vial with a pipet. By this means, nine 2,4-dinitrophenylhydrazine (DNPH)-derivatized ketones and aldehydes were separated with high resolution. Not only was analysis time shortened by more than one half, but the detection limit was greatly improved compared to that in isocratic elution. The latter was achieved using the P/ACE 5510 system (Beckman Instruments, Fullerton, CA, U.S.A.), which moved the mobile phase vials automatically. The stop-flow technique was utilized during transfer. It had no effect on solute retention. With this method, the concentration and type of organic modifier in the mobile phase could be changed. A mixture of 13 aromatic hydrocarbons was separated completely in 14 min by changing the mobile phase from 80% methanol to 80% acetonitrile and 90% acetonitrile in a sequential step mode. The RSD of the retention time of each component in six consecutive injections was below 0.374%. All of these results demonstrate that stepwise gradient elution of capillary electrochromatography may be useful in the analysis of complex environmental samples.

Electrophoresis, Capillary↗

PubMedDate not supplied

A probiotic approach to caries management.

The surgical approach has been the predominate mode of caries management for the past 150 years. Dentistry has, however, in recent years moved toward an antibiotic/antimicrobial model of disease management. This approach, however, raises serious questions: (1) do the antibiotic/antimicrobial agents (chlorhexidine, povidone iodine, fluoride, etc) kill all offending organisms?; (2) if so, do the agents preclude the re-entry of the same organisms from external sources?; and (3) if the agents do kill all the offending organisms, do any remaining pathogenic organisms have selective advantage in repopulating the tooth surfaces? To overcome the problems inherent in an antibiotic/antimicrobial approach, probiotic methods are currently under study as means of caries management. This paper discusses probiotic approaches, such as genetically modified Streptococcus mutans and targeted antimicrobials in the management of dental caries. Implications for this approach in the management of other diseases are also presented.

Anti-Bacterial Agents↗