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Biomedical subjects

H Cheng

Publications and source records attributed to H Cheng.

At least 469 records · Page 26Linked to original sources
PubMed1985

Functional gap junctions in mouse small intestinal crypts.

We demonstrate intercellular transfer of Lucifer yellow and the existence of gap junctions in isolated mouse small intestinal crypts. The pattern of dye transfer approximates the normal pattern of cell proliferation and differentiation in the intestinal epithelium. These findings indicate that the cells of normal crypts form an effective intercellular continuum. This intercellular route may function in the establishment of chemical, ionic, or electrical fields, which in turn may play a role in the control of cell proliferation, differentiation, and secretion in the crypt.

Animals↗
PubMed1985

The penetration of Sorbinil, an aldose reductase inhibitor, into lens, aqueous humour and erythrocytes of patients undergoing cataract extraction.

Two studies to investigate the penetration of the aldose reductase inhibitor, Sorbinil, were conducted. In the first study, 24 diabetic patients undergoing intracapsular extraction were randomised into three groups on a double masked basis. In the week immediately preceding the operation, all patients were requested to take two capsules daily before breakfast. Each capsule contained 200 mg Sorbinil, 100 mg Sorbinil, or a placebo. On measuring Sorbinil levels in lens, plasma and erythrocytes using HPLC, three clearly defined groups of patients were obtained. In one group no Sorbinil was detected, in the second group there were moderate levels of Sorbinil, while the third group had significantly higher levels of Sorbinil. The ratio of erythrocyte/plasma Sorbinil was 0.225, while the ratio for lens/plasma was 0.7, for both groups where Sorbinil was detected. In a second study, 20 patients were treated topically with a single dose of 0.5 mg ophthalmic Sorbinil at times ranging from 0-14 hr preoperatively. Sorbinil was detected in both lens and aqueous. Transport into the lens was complete within about 2 hr, and although aqueous levels were negligible after 6 hr, Sorbinil persisted up to 14 hr in the lens. Three out of 16 patients taking Sorbinil orally developed a maculopapular rash with pyrexia approximately 8 days after commencing the drug. No side effects were noted in any patients given the topical ophthalmic preparation.

Aged↗
PubMed1985

Ca2+ channel blockers stimulate ileal and colonic water absorption.

The effects of calcium channel blockers on water transport in the rat ileum and distal colon were studied in vivo using the single-pass perfusion technique. Parenteral but not intraluminal verapamil, and parenteral nifedipine increased ileal water absorption, with effects lasting at least 60 min. In contrast, i.p. verapamil had no effect on rat distal colonic water absorption, whereas intraluminal verapamil significantly stimulated colonic water absorption. Similarly, perfusing the rat descending colon with low-Ca2+ Ringer's-HCO3 stimulated colonic water absorption. Verapamil was not antisecretory because the theophylline-induced decrease in ileal water transport was similar in control animals and in animals pretreated with i.p. verapamil. In addition, nifedipine stimulated active Na and Cl absorption in rabbit ileum. These studies demonstrate that the Ca2+ channel blockers verapamil and nifedipine stimulate basal absorption of water in rat ileum and distal colon in vivo, and stimulate active Na and Cl absorption in rabbit ileum in vitro. The verapamil stimulation of colonic water absorption from the luminal surface was duplicated by perfusion with a low-Ca2+ bathing solution. This suggests the presence of apical membrane Ca2+ channels in rat colon, which appear to be involved in regulation of basal water transport, and that these Ca2+ channels are in a partially open state under basal conditions. Because verapamil stimulates absorption systemically (ileum) as well as intraluminally (colon), Ca2+ channel blockers have properties that might be useful in treatment of diarrheal diseases.

Animals↗
PubMed1985

Human cord blood suppressor T lymphocytes: I. Phenotype and target of the inducer of suppressor cell factor.

The present study examines the characteristics of the cord suppressor T cells and their targets. When an inducer of suppressor T cell factor (TisF) from culture supernatant of alloantigen-activated cord lymphocytes was used as a source of suppression, adult lymphocyte response to soluble antigen candidin, alloantigens, and pokeweed mitogen were all suppressed. These results suggest that TisF acts primarily on T cells in an antigen-nonspecific fashion. Furthermore, preculture T cell irradiation, but not T8+ cell depletion, of adult lymphocytes abrogated the suppressive effect of TisF on the PWM-stimulated IgG production, suggesting that the target of TisF belongs to the radiosensitive T8-(T4+) T cell subset. When different cord T cell subsets were tested for suppressor activity, only radiosensitive T4+ cells were capable of suppressing IgG production by adult lymphocytes. Neither preculture T8+ cell depletion nor irradiation of adult T cells affected the suppression. Taken together, these results suggest that the suppressor activity of cord T cells originated from an inducer of suppressor cells that activates radiosensitive T4+ suppressor effector cells through TisF. In turn, these effector cells act on either radioresistant T4+ helper T cells or B cells or both.

Adult↗
PubMed1985

Comparison between the complications of cataract surgery following local anaesthesia with short stay and general anaesthesia with a five-day hospitalisation.

In December 1979 97 patients underwent intracapsular cataract extraction under local anaesthetic with planned discharge on the day after operation. Twenty-three of these patients had a prolonged stay in hospital, and five of these required early operative intervention following surgical complications. Sixteen patients did not attain a visual acuity better than 6/18. The visual outcome and postoperative course are compared with those of a similar group of patients who stayed in hospital for five days after intracapsular cataract extraction.

Adult↗
PubMed1984

Increased activity of plasminogen activators during involution of the rat ventral prostate.

Plasminogen activator was measured in the ventral prostates of non-castrated, castrated, and androgen-treated rats to determine whether changes in this activity correlated with the process of glandular involution. While the activity was very low in cytosolic extracts from the prostates of non-castrated rats, 2 days following castration the plasminogen activator activity increased in a near-linear fashion such that by day 7 it was 10-fold higher in terms of specific activity (per mg of protein) and cellular concentration (per mg of DNA). During this interval there was a rapid decrease in the cell population of the prostates. Treatment of the 7-day castrated rats with the potent androgen, dihydrotestosterone, both reduced the plasminogen activator activity and restored the cell number in a dose-related manner. Gel electrophoretic analysis revealed two major bands of plasminogen activator activity in the cytosolic extracts from 4- and 7-day castrated rats, plus additional minor bands in samples from 10- and 14-day castrated rats. Approx. 10% of the cellular concentration of plasminogen activator activity was recovered in association with an 18000g pellet fraction from the prostates; this fraction showed less heterogeneity of the plasminogen activator forms as observed by gel electrophoresis. Inhibitor studies indicated that the 18000g pellet fraction from the prostates of non-castrated rats possessed some plasminogen activator inhibitor activity, but the relative concentration of the inhibitor activity was small. We conclude that the involution of the prostate is probably associated with increased synthesis of plasminogen activators through a de-repression process which may involve loss of androgen receptors.

Animals↗
PubMed1984

Immunoregulatory function of human cord blood lymphocytes on immunoglobulin production.

The functional maturity of human umbilical cord blood B lymphocytes and the immunoregulatory activity of cord T lymphocytes were assessed by measuring the in vitro immunoglobulin production by B cells from either cord or adult blood. Supernatants from 48-hr pokeweed-mitogen (PWM) stimulated cord or adult lymphocyte cultures were added to cord or adult B cell cultures in the presence of PWM; a significant amount of immunoglobulin was produced in adult B cell cultures only. Adult B or T cells were then cocultured with cord T or B cells; a significant amount of immunoglobulin was again found only in adult B cell cultures. These results indicated that cord B cells were functionally immature and that cord helper T cell function was adequate but masked by excessive suppressor activity. Indeed, addition of cord T cells but not of allogeneic adult T cells to PWM stimulated adult lymphocyte cultures inhibited their immunoglobulin production; this confirmed cord T cells' increased suppressor activity. Cord T cells were not intrinsically suppressive since they failed to suppress immunoglobulin production by Epstein-Barr Virus (EBV) transformed B cells. They could be activated, however, by PWM or allogeneic cells (in mixed lymphocyte cultures) and their effect was mediated via soluble factor(s) as demonstrated by the suppressor effect of these culture supernatants on immunoglobulin production by unfractionated adult lymphocytes. In contrast, when these supernatants were added to T cell-depleted adult lymphocyte cultures, enhancement rather than suppression was observed. These results indicated that the soluble factor(s) released by Cord T lymphocytes was not suppressing per se but induced suppression through activation of suppressor cells.

Adult↗
PubMed1984

Long-term follow-up of intraocular lens implants: the first 127 compared with the latest 100 of the same style in a span of 9 years.

The long-term follow up of the first 127 patients (127 eyes) treated by one surgeon with cataract extraction and Federov I lens implantation is reported. The proportion of patients achieving visual acuity of 6/12 or better had decreased since the one year follow-up. Corneal oedema was the most serious long-term complication. This group of patients is compared with the latest 100 patients (100 eyes) operated on by the same surgeon using the same type of implant. There was a reduction of some operative complications, and improvement in surgical techniques had resulted in a lower sample endothelial cell loss at one month.

Aged↗
PubMed1984

Methods for the determination of epithelial cell kinetic parameters of human colonic epithelium isolated from surgical and biopsy specimens.

The purpose of this study is to introduce the application of new approaches to the determination of human colonic epithelial cell kinetic parameters. The isolation of pure and intact colonic epithelium from both surgical and biopsy specimens forms the basis of these approaches. The isolated epithelium is used in the determination of cell kinetic parameters by (a) flow cytometry, (b) Coulter counting, (c) dried cell preparations, and (d) crypt squashes. Using these methods, the following results were derived. The proportion of cells in the various phases of the cell cycle in the sigmoid epithelium was determined to be 81.6% +/- 2.15% (means +/- SE) in G1/G0 phase, 15.2% +/- 1.86% in S phase, and 3.2% +/- 0.62% in G2 + M phases. In the rectal epithelium, there were 79.6% +/- 3.35% in G1/G0 phase, 16.4% +/- 4.86% in S phase, and 4.08% +/- 1.90% in G2 + M phases. The total cell population in sigmoid epithelium was approximately 4.2 X 10(6) +/- 5.46 X 10(5) cells per cm2, and there were approximately 2.5 X 10(3) +/- 1.57 X 10(2) cells in each colonic crypt. Therefore, the number of crypts per square centimeter of human sigmoid mucosa could be estimated to be approximately 1.68 X 10(3). Lastly, in sigmoid epithelium, columnar cells of human sigmoid mucosa could be estimated to be approximately 1.68 X 10(3). Lastly, in sigmoid epithelium, columnar cells accounted for 76.3% +/- 6.18% of the epithelial cells, whereas the remaining epithelial cells, 23.7% +/- 4.08%, consisted of mucous cells.

Cell Count↗
PubMed1984

Intraocular lens implantation: should we abandon intracapsular surgery?

The most important late complication of a longitudinal study of iris-supported lens was bullous keratopathy. Endothelial cell loss after using the closed chamber technique for lens insertion was more than halved. The cell loss rate after intracapsular extraction with a Federov I lens was compared with that after extracapsular extraction with an iridocapsular lens. The intermediate results did not show any significant difference between groups and there were eyes in both groups with a large initial loss which appeared to lose cells at a faster rate.

Cataract↗
PubMed1983

Isolation of 3 S androgen receptors from salt-resistant fractions and nuclear matrices of prostatic nuclei after mild trypsin digestion.

The physical properties of two types of androgen-binding sites in prostatic nuclei were compared and found to be identical. The first type was released from chromatin by micrococcal nuclease digestion and solution in 0.6 M NaCl; the second resisted such treatment and remained associated with nuclear structures. After in vivo administration of [1,2-3H]testosterone to 24-h castrated rats and sonication of purified nuclei, 90% of the nuclear radioactivity was extracted with nuclease/salt treatment and was found by sucrose density gradient analysis to be associated with a 3 S androgen receptor. If sonication was omitted, 50 to 60% of the nuclear radioactivity was recovered in the nuclease/salt-resistant pellets or bound to nuclear matrices. Mild digestion of either of these particulate fractions with trypsin resulted in the release of a 3 S androgen receptor. After in vitro isotope-exchange labeling with [1,2-3H]dihydrotestosterone, the sedimentation coefficient, steroid specificity, and dissociation constant of the androgen receptors released by trypsin digestion of nuclease/salt-resistant pellets or nuclear matrices were similar to those of the receptors extracted by nuclease/salt treatment. These results indicate first, that all androgen-binding sites in prostatic nuclei can be released, either with nuclease/salt or trypsin digestion procedures to yield a 3 S androgen receptor with uniform binding characteristics, and second, that the androgen receptors are distributed between two intra-nuclear pools--one containing about 10,000 molecules/nucleus sensitive to micrococcal nuclease digestion and salt and the other containing about 8,000 to 13,000 androgen receptors tightly bound to the nuclear matrix.

Animals↗
PubMed1983

Cell production in mouse intestinal epithelium measured by stathmokinetic flow cytometry and Coulter particle counting.

The rate of cell production in the crypt population of the intestinal epithelium has been determined previously. However, the complex geometry of the tissue makes determination of the rate of cell production in the epithelium as a whole, by traditional methods, extremely difficult if not impossible. In this report, stathmokinetic flow cytometry was used for the direct determination of the rate of cell production in the mouse intestinal epithelium. Mice were given an intraperitoneal injection of colcemid (2.5 mg/kg) and killed 25, 45, 65 and 90 min after injection. The percentage of cells with 4N DNA (G2 and M phase cells) in the epithelium at each time interval was determined with flow cytometry. The results were fitted by linear regression and the rate of cell production derived from the slope of the regression line. Thus, the rate of cell production was found to be 1.86% +/- 0.44 (means +/- SE) per hour in the jejunal epithelium and 1.66% +/- 0.48 per hour in the colonic epithelium. The turnover time of the epithelium as a whole was determined from the inverse of the rate of cell production, and was found to be 53.8 h +/- 12.6 in jejunum and 60.2 h +/- 17.3 in colon. Coulter particle counting was used to measure the number of cells in the intestinal epithelium. The number of epithelial cells was found to be 1.90 X 10(7) +/- 3.11 X 10(5) cells per cm2 in the jejunum and 8.98 X 10(6) +/- 8.05 X 10(5) cells per cm2 in the colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗