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Biomedical subjects

L M Li

Publications and source records attributed to L M Li.

At least 73 records · Page 4Linked to original sources
PubMed1993

Prevalence of human papillomaviruses 16 and 18 in transitional cell carcinoma of bladder.

It has been speculated that human papillomaviruses (HPV) might be a causative agent of transitional cell carcinoma of the bladder. With the polymerase chain reaction technic, fresh specimens of 53 transitional cell carcinomas of the bladder were examined, and bladder epithelium from 12 patients with hyperplasia of prostate and peripheral blood lymphocytes of 8 normal individuals served as controls. The primers set for HPV-16 and 18 were selected from E6/E7 regions of open reading frames. HPV-16 was positive in 52.8% of the specimens examined, whereas HPV-18 positive in only 3.7%. No controls showed either HPV-16 or 18. Reports on the role of HPVs in carcinogenesis of bladder are scanty and yet there exist conspicuous discrepancies among them. There is a diversity of opinions on the contamination and variation of technical procedures. More work should be done before the relationship between HPV-16 and development of bladder carcinoma can be clarified.

Base Sequence↗
PubMed1993

[Calcium metabolism in normal pregnancy and pregnancy induced hypertension].

The concentration of serum calcium (Ca), phosphorus (P), alkaline phosphatase (AKP), parathyroid hormone (PTH) and calcitonin (CT) of 66 healthy pregnant women were measured at 2nd trimester, full term, 3 days and 6 weeks postpartum. These parameters were also measured in 56 patients with moderate or severe PIH in late pregnancy. The results showed that in spite of the obvious changes observed in these parameters at various periods, regulatory system of calcium metabolism in normal pregnancy was not affected. By contrast, calcium metabolism imbalance was seen in patients with moderate and severe PIH. The occurrence of PIH between two groups of pregnant women (50 each) with or without calcium supplement was compared. The pattern of calcium metabolism in normal pregnancy was summarized, and the pathogenesis of PIH related to calcium metabolism was discussed. The study provides an important basis for calcium supplementation during pregnancy and for using calcium antagonists to treat PIH patient.

Alkaline Phosphatase↗
PubMed1992

A cross-over study of three oral contraceptives containing ethinyloestradiol and either desogestrel or levonorgestrel.

A randomised cross-over trial was performed to compare the pharmacodynamic actions of three low-dose oral contraceptives (OCs): Marvelon (150 micrograms desogestrel (DSG)+ 30 micrograms ethinyloestradiol (EE)), Mercilon (150 micrograms DSG + 20 micrograms EE) and Microgynon (150 micrograms levonorgestrel (LNG) + 30 micrograms EE). None of the OCs produced any significant changes in serum cholesterol, LDL-C and apoprotein B. Triglycerides were increased by the desogestrel OCs but not by Microgynon. The latter however increased the glucose and insulin responses to a glucose tolerance test whereas Marvelon and Mercilon had no effect. HDL-C increased with Marvelon, was unchanged with Mercilon and was decreased with Microgynon. Apoprotein AII was increased by all three OCs but only the DSG OCs increased apoprotein AI. All OCs produced similar increases in caeruloplasmin but the increase in SHBG was much greater with Marvelon and Mercilon than with Microgynon. Testosterone was reduced more with Microgynon than with the DSG OCs. Many of the changes reflect the strong anti-oestrogenic action of LNG on metabolic parameters compared to DSG. Except for the effect on HDL-C, there was little difference between Marvelon and Mercilon on metabolic parameters and this complements the findings from large-scale clinical trials of the two OCs. Mercilon, therefore provides a very satisfactory alternative to Marvelon.

Adult↗
PubMed1991

Expression and assembly of spectrally active recombinant holophytochrome.

To develop an in vitro phytochrome assembly system, we have expressed an oat phytochrome cDNA in both the yeast Saccharomyces cerevisiae and the bacterium Escherichia coli. Analysis of soluble protein extracts showed that the recombinant apophytochromes were full-length and capable of covalently attaching the phytochrome chromophore analogue phycocyanobilin. Difference spectra indicated that in vitro-assembled holophytochrome species were photoreversible; however, maxima and minima difference absorption values were blue-shifted relative to those of the native photoreceptor. Extracts containing the recombinant apophytochromes were also incubated with phytochromobilin, the natural chromophore synthesized from biliverdin by cucumber etioplast preparations. In these experiments, the difference spectrum obtained was identical to that of native oat holophytochrome. These results suggest that the recombinant apophytochromes adopt a structure similar to that of the apoprotein biosynthesized in vivo. ELISAs were used to quantitate phytochrome expression levels in both yeast and E. coli extracts. These measurements show that 62-75% of the phytochrome apoprotein in the soluble protein extract was competent to assemble with bilins to form spectrally active holophytochrome.

Cloning, Molecular↗
PubMed1991

Role of nitric oxide in lysis of tumor cells by cytokine-activated endothelial cells.

The purpose of these studies was to determine whether nitric oxide produced by cytokine-activated murine lung vascular endothelial cells plays a role in their lytic destruction of M-5076 reticulum cell sarcoma. Vascular endothelial cells harvested from perfused lungs of mice were adapted to grow in culture. Cloned lines ascertained to be of endothelial origin were incubated in vitro with interferon gamma and tumor necrosis factor. Lysis of radiolabeled tumor cells and accumulation of nitrite in the culture medium were determined at several time points. The concentration of nitrite in the culture medium directly correlated with endothelial cell-mediated tumor cell lysis. Endothelial cells cultured in L-arginine-free medium did not produce significant tumor cell lysis nor accumulation of nitrite in the medium. Both tumor cell lysis and nitrite accumulation were observed when the deficient medium was reconstituted with L-arginine, suggesting that endothelial cell-mediated tumor lysis was dependent on L-arginine, a precursor of nitric oxide. Moreover, specific inhibition of nitric oxide synthesis by NG-methyl-L-arginine resulted in complete inhibition of endothelial cell-mediated lysis of the M-5076 reticulum cell sarcoma. Similarly, treatment of cytokine-activated endothelial cells with dexamethasone inhibited both target cell lysis and production of nitrite. Collectively, these results suggest that nitric oxide plays a major role in the lysis of tumor cells mediated by cytokine-activated endothelial cells.

Animals↗
PubMed1991

Direct in vitro lysis of metastatic tumor cells by cytokine-activated murine vascular endothelial cells.

The purpose of these studies was to determine whether vascular endothelial cells can be treated with various cytokines to become cytotoxic against tumorigenic target cells under defined conditions in vitro. Microvascular endothelial cells were isolated from immunocompetent mice by perfusion of lungs grown in culture, cloned, and then characterized. The cloned microvascular endothelial cells were activated by incubation with a combination of recombinant tumor necrosis factor alpha and recombinant-gamma interferon (10 units/ml each) for 24 h. Activated endothelial but not control endothelial cells (incubated in medium alone, recombinant tumor necrosis factor alpha alone, or recombinant gamma interferon alone) produced significant lysis of mouse reticulum cell sarcoma and two different mouse melanomas. Moreover, at the concentrations used here, recombinant tumor necrosis factor alpha and recombinant gamma interferon did not produce direct target cell lysis. The activated endothelial cell-mediated tumor cell lysis depended on the continuous presence of the cytokines and was not due solely to initial target cell binding. The results demonstrate that, like macrophages, microvessel endothelial cells exposed to low levels of cytokines are capable of lysing tumor cells.

Animals↗
PubMed1991

Characteristics of binding of endothelin-1 and endothelin-3 to rat hearts. Developmental changes in mechanical responses and receptor subtypes.

Endothelin-1 (ET-1) and endothelin-3 (ET-3) produced positive inotropic effects on electrically stimulated left atria and increased the frequency of spontaneously beating right atria of adult rats. The potency of the inotropic effect of ET-1 was greater than that of ET-3, but the potencies of the chronotropic effects of ET-1 and ET-3 were not significantly different. In the neonatal atria, ET-1 and ET-3 also induced positive inotropic and chronotropic responses. ET-1 and ET-3 showed weak or no cardiotonic effects on the adult ventricles, whereas they caused marked positive inotropy in the neonatal ventricles. The characteristics of binding sites for ET-1 and ET-3 were very similar between the atria and the ventricles of the rat neonate. Saturation and competition binding experiments have shown that neonatal cardiac membranes from both atria and ventricle have two distinct binding sites for endothelin, that is, a low-affinity and a high-affinity site. ET-1 was found to bind to the low-affinity sites with a significantly lower Kd than ET-3, whereas the estimated Kd values for ET-1 and ET-3 at the high affinity sites were similar. In contrast, the binding sites in adult atria were different from those of the ventricles: only a single binding site for both ET-1 and ET-3 was detected. Adult atrial membranes, on the other hand, had two distinct binding sites similar to those of neonatal membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

[Use of MMPI (Minnesota multiphasic Personality Inventory) in the evaluation of patients with chronic pain syndrome].

The MMPI was performed in 25 patients with chronic pain syndrome to evaluate the personality trait. The results showed an elevation in scales 1, 2, 3 in 64% of the patients. The inventory was effective on the assessment of patients. It offered standardization and objective visualization of patients' psychical involvement. Also, it can serve as a prognostic factor for psychotherapy and surgery.

Adolescent↗
PubMed1990

A pharmacodynamic and pharmacokinetic study of the Chinese No. 1 pill.

A pharmacodynamic and pharmacokinetic study of the Chinese No. 1 pill, a combined oral contraceptive containing 35 micrograms ethynyloestradiol (EE) and 600 micrograms norethisterone (NET), was performed in 29 women over a period of six months. Blood samples for analysis were taken during a pretreatment cycle, the first and 6th treatment cycles and post-treatment. Minor changes in carbohydrate metabolism occurred and these were particularly noticeable when the incremental areas under the serum concentration-time curves for both glucose and insulin in response to a glucose tolerance test were calculated. No changes occurred in the serum glycosylated haemoglobin levels. The serum concentrations of all the lipids measured (total cholesterol, triglycerides, LDL-C, HDL-C and apolipoproteins AI, AII and B) were significantly increased on treatment as were levels of Factor X, SHBG and caeruloplasmin whereas antithrombin III decreased. In 38 of the 40 treatment cycles, ovulation was suppressed. In one cycle serum oestradiol and progesterone levels showed a typical ovulatory pattern and in another there was evidence of follicular activity without ovulation. Serum EE concentrations showed a similar pattern in both treatment cycles showing that co-administration of NET did not affect EE metabolism. Serum NET levels were higher in the 6th than in the first treatment cycles. On comparing pharmacodynamic and pharmacokinetic parameters, the only statistically significant correlations were between the percentage change in triglycerides and SHBG and serum NET, but not EE concentrations, and between apolipoproteins AI and serum EE.

Adult↗
PubMed1990

Intrabronchial implantation of the Lewis lung tumor cell does not favor tumorigenicity and metastasis.

The purpose of these studies was to determine whether the orthotopic implantation of the Lewis lung tumor favors tumorigenicity and production of metastasis as compared with implantation at an ectopic site. Different numbers of viable cells were implanted subcutaneously (footpad), intrabronchially, or intrathoracically into groups of syngeneic mice. Tumorigenicity, production of distant metastases and survival were recorded. Tumor cells implanted subcutaneously produced fast-growing local tumors and numerous spontaneous lung metastases. Tumor cells implanted intrabronchially produced slow-growing tumors that did not produce distant metastasis. Since radiolabeled cells implanted into different sites exhibited similar patterns of survival, the differences in behavior of 3LL cells in the skin or lung were due to other factors. We conclude that for the Lewis lung carcinoma, orthotopic implantation does not favor increased tumorigenicity and metastatic potential.

Animals↗
PubMed1990

[Tracking of blood pressure in children].

In order to find out whether there is a "tracking phenomenon" of blood pressure in children, we examined in 1981 a group of 2,946 children (ages 4-14 years) and reexamined 2,588 of them (88.2%) in 1985. The results indicate: There is a weak degree of blood pressure "tracking phenomenon" in childhood. "Tracking coefficients" were 0.24 to 0.56 for systolic blood pressure, and 0.15 to 0.38 for diastolic pressure after four years of follow-up. Thirty percent of the children whose blood pressure were above the 90th percentile of the systolic blood pressure distribution at the first examination remained at the same level after four years. It is important to study further those subjects who show a consistent high percentile of blood pressure during childhood.

Adolescent↗
PubMed1987

[Chemoprevention of cancer of the uterine cervix--preliminary study on the intervention of the cervical precancerous lesion by retinamide RII].

Twenty seven women with mild, moderate or severe cervical dysplasia proven by pathology were treated by retinamide RII suppository. Retinamide RII suppository, 10 mg QD, was given intravaginally for six months (three months as a course). Clinical examination, Papanicolaou cytology and tissue biopsy under colposcope were carried out before and after treatment. The results indicated that after the second course, 26 out of 27 patients responded; of them, precancerous lesions disappeared in 24 and even normal squamous epithelium was observed in 3. The overall response rate was 96.29% and the marked response rate was 88.89%. The general side effects were mild. There was little cervical and vaginal irritation which was well tolerated. The results of this clinical trial make available a practical base for chemoprevention of cervical cancer.

Antineoplastic Agents↗