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Biomedical subjects

W K Li

Publications and source records attributed to W K Li.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Interceptive activity of epostane in pregnant rats and rhesus monkeys].

A complete interceptive action on pregnancy was shown after ig epostane (Epo) 48 and 96 mg/kg on d 10 of pregnancy in rats. ED50 (95% fiducial limits) of Epo was 20.7 (16.3-26.3) mg/kg. Epo 48 mg/kg ig on d12, 14 and 16 of pregnancy lowered rat plasma progesterone concentrations (P less than 0.05) and plasma corticosterone on d 16 of pregnancy (P less than 0.05). Epo 35 mg/(kg.d) was given ig on d 50-54 of pregnancy in rhesus monkeys. Vaginal bleeding was seen in all of the 6 treated monkeys. Complete expulsions of fetal and placental materials occurred in 5 of the treated monkeys, among which 2 aborted on d 53 and the other 3 on d 54 of pregnancy. Plasma progesterone concentrations of the treated monkeys were lowered on d 52, 53 and 54 of pregnancy (P less than 0.05) and plasma estradiol on d 51, 52, 53, 54 and 55 (P less than 0.05), while there were no significant differences in plasma hydrocortisone. Epo may be a valuable supplement to the existing methods of female contraception.

Abortion, Induced↗
PubMed1989

Shipboard analytical flow cytometry of oceanic ultraphytoplankton.

Shipboard analysis of marine ultraphytoplankton by flow cytometry is a powerful method to classify these cells according to in vivo fluorescence characteristics and size. At present, this ataxonomic-allometric approach allows recognition of phycoerythrin-containing cyanobacteria, cryptomonads, very small red-fluorescing cells (presumably prochlorophytes), and eukaryotic algae of various sizes in many open ocean samples. The speed at which flow cytometric analysis can be performed on freshly collected samples permits a high degree of sampling resolution in both space and time. A flow cytometric view is presented of the vertical distribution of ultraphytoplankton at various sites in the north Atlantic and of experiments wherein phytoplankton were incubated in an artificial light gradient and under simulated in situ conditions.

Atlantic Ocean↗
PubMed1987

Temperature characteristics of photosynthetic and heterotrophic activities: seasonal variations in temperate microbial plankton.

The seasonal variation in temperature characteristics of photosynthetic and heterotrophic activities in the microbial plankton of Bedford Basin, Nova Scotia, was investigated. Measurements were made of the photosynthetic uptake of [C]bicarbonate and its incorporation into cellular protein as well as the heterotrophic uptake of H-labeled amino acids and their incorporation into cellular protein. Activity-temperature curves were analyzed objectively by nonlinear estimation of parameters from various mathematical models. Over the seasonal cycle, the cardinal temperatures and a parameter formally equivalent to the thermodynamic enthalpy of activation for most of the four processes measured were positively correlated with the water temperature. The temperature sensitivity of metabolic activity (i.e., change in activity per unit change in temperature) was indexed by the tangent to the activity-temperature curves. When this index was expressed in dimensionless form by normalization to the scaling factor of the activity-temperature curves, the resulting relative temperature sensitivity, evaluated at the prevailing temperature, proved to be statistically invariant throughout the year. During the height of the spring bloom, the water temperature (-0.3 degrees C) was not so low as to inhibit metabolic activity of either the phytoplankton or the bacterioplankton. The evidence suggests that heterotrophic utilization of products is not suppressed during the spring phytoplankton bloom.

Journal Article↗
PubMed1984

Microbial uptake of radiolabeled substrates: estimates of growth rates from time course measurements.

The uptake of [3H]glucose and a mixture of 3H-labeled amino acids was measured, in time course fashion, in planktonic microbial assemblages of the eastern tropical Pacific Ocean. The average generation times of those portions of the assemblages able to utilize these substrates were estimated from a simple exponential growth model. Other workers have independently used this model in its integrated or differential form. A mathematical verification and an experimental demonstration of the equivalence of the two approaches are presented. A study was made of the size distribution of heterotrophic activity, using time course measurements. It was found that the size distribution and the effect of sample filtration before radiolabeling were dependent on time of incubation. In principle, it was possible to ascribe these time dependences to differences in the specific growth rate and initial standing stock of the microbial assemblages.

Amino Acids↗
PubMed1983

Pelvic Ewing's sarcoma. Advances in treatment.

In a study of eighteen patients with pelvic Ewing's sarcoma who were treated with a multidisciplinary approach, chemotherapy was effective in controlling systemic spread of the tumor. Surgery coupled with improved methods of chemotherapy provided results that were statistically superior to those obtained with radiation and chemotherapy alone in control of the local pelvic lesion. A twofold increase in the survival rate was seen at a median follow-up of thirty-six months in the patients who had the resection. Our results suggest that pelvic Ewing's sarcoma is best treated by initial chemotherapy, followed by local wide marginal resection of the pelvic lesion coupled with perimeter radiation therapy and concluded with additional chemotherapy. Survival rates of patients with pelvic Ewing's sarcoma may then approach the excellent survival rates of patients with lesions in more favorable anatomical locations.

Adolescent↗
PubMed1976

Studies on bacteriophage distribution: virulent and temperate bacteriophage content of mammalian feces.

Freshly voided samples of the feces of cows, pigs, and humans were analyzed for the enumeration of cell-free plaque-forming units (PFU) of coliphages and Salmonella phages. Coliphage PFU counts per gram (wet weight) of feces were found to range from less than 10(1) to greater than 10(7). Salmonella phages were found in three out of five porcine samples, but none were found in the four bovine samples analyzed. Virulent coliphages related to the phiX174/S13 serological group showed some "habitat preference" in that the S13 type of phages was found only in pig feces, whereas the phiX174 type of phages was found only in cow dung. Temperate coliphages were detectable in a majority of samples of both human and porcine origin but were infrequently found in bovine samples. About 80% of the temperate coliphages of fecal origin have been found to be serologically related to phage HK022 (Dhillon and Dhillon, 1973), and all are efficiently inducible by ultraviolet light irradiation. However, considerable diversity with the group was found when the prophage immunity pattern of 10 randomly selected isolates was examined.

Animals↗
PubMed1976

Ankle-knee synchronous in a new endoskeletal above-knee prosthetic mechanism: a preliminary report.

A new above-knee prosthetic mechanism with synchronous motions of the knee and ankle has been designed based on kinematic principles. Knee flexion is synchronized with ankle dorsiflexion by a synchronizer rod and lever. Unlike other above-knee units, the knee joint is aligned about one inch in front of a line between the hip and the ankle joints, which appears to decrease the energy requirements of gait. The swing-phase control system provides constant friction during ordinary cadence and variable friction during rapid swinging of the leg. The addition of a quadrilateral socket, a modified SACH foot and a cosmetic foam plastic cover provides the complete endoskeletal above-knee prosthesis. The resulting gait has been found to be faster, easier and more natural, and the three optional knee settings serve the needs of different amputees and activities.

Ankle Joint↗
PubMedDate not supplied

Survey of air-borne allergic pollens in North China: contamination with ragweed.

This paper presents the survey of 9 districts in North China with an object of understanding more about geographical distribution of air-borne pollens in relation with allergic diseases in the upper respiratory system. The findings prove to be a good guidance, beneficial both to the physicians who are treating the cases and to the patients who are receiving the treatments. The components of the peaks of the curves in Spring are nearly the same, they are usually formed of Ulmus (elm), Populus (poplar) and Selix (willow), with the exception that in the Spring curve of Lanzhou, Biota Orientalis dominates and at Huohot, Ulmus (elm) dominates. Like in the report on air-borne pollens in Peking, made by C. T. Chang as well as in our report on air-borne pollens survey in 9 districts in North China, Artemisia (sage) is found to be the chief component of the Summer-Autumn curve and the major offender in Summer-Autumn seasons in the etiology of upper respiratory allergic diseases. In contradistinction to Artemisia (sage), there are two exceptions such as in south China: In Shenghai, Ricinus (castor bean) and Humulus (Hops) are found to be the major offender instead of Artemisia (sage) and At Kwangzhou, Kwangdong province Wood Ephedra, Wild Amaranth (pigweed) are also found to be major offenders instead of Artemisia (sage). In addition to the major offender, Artemisia (sage) which was said to be dominant in Shenyang (Moukden) of Laoning province by Yuchin (cited from POLLINOSIS by Shih Ruei, Ragweed was first discovered at Shenyang (and Tehling, Fushuen and Dandong). A question is raised "How it came to China"? Preventive measures must be taken to eradicate it, otherwise it certainly will spread all over China.

Air Pollutants↗