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Biomedical subjects

Y L Li

Publications and source records attributed to Y L Li.

At least 109 records · Page 6Linked to original sources
PubMed1990

Studies of the synthesis of biomarkers. VII. Synthesis of 5 alpha-(17R,20R)-14,15-secocholestane.

5 alpha-(17R,20R)-14,15-Secocholestane (12) was synthesized from cholesterol (1) in 12 steps. The key intermediate, 5 alpha-cholest-14-en-3 beta-yl acetate (4), underwent ozonization, reduction, hydrolysis, and oxidation to provide 5 alpha-14,15-secocholesta-3,14,15-trione (8). One of the Clemmensen reduction products of 8 is 5 alpha(17R,20R)-14,15-secocholest-15-ol (11); treatment of the alcohol (11) with tosyl chloride and subsequent reduction with lithium aluminum hydride yielded the target molecule (12).

Aluminum↗
PubMed1990

Transient effects of subcutaneously administered prostaglandin E2 on cancellous and cortical bone in young adult dogs.

The transient effects of prostaglandin E2 (PGE2) on cancellous and cortical bone in iliac crests and mid-tibial shafts of nine intact young adult dogs were evaluated following 31 days of treatment. Histomorphometric bone changes were characterized from in vivo fluorescent double-labeled undecalcified bone specimens. PGE2 caused an increase in cancellous bone remodeling evidence by increased in activation frequency; increased percent eroded and formation surfaces; increased mineral apposition and bone formation rates; and shortened resorption, formation, and total bone remodeling periods. Activated cancellous bone remodeling did not lead to decreased cancellous bone mass, indicating an imbalance between bone resorption and formation in favor of formation (activation----resorption----stimulated formation; A----R----F increases) at remodeling sites. The PGE2 treatment activated bone modeling in the formation mode (activation----formation; A----F) at the periosteal and endocortical surfaces and increased activation frequency of intracortical bone remodeling in the tibial shaft. Increased modeling activation converted quiescent bone surfaces to formation surfaces with stimulated osteoblastic activity (i.e., increased percent labeled periosteal and endocortical surfaces, mineral apposition rates, and woven and lamellar trabecular bone formation) leading to 9- to 26-fold increases in newly formed bone mass in subperiosteal, subendosteal, and marrow regions, compared to controls. However, increased intracortical bone remodelling elevated remodeling space (i.e., increased cortical porosity), producing a bone loss that partially offsets the bone gain. The combined events lead to a positive bone balance in PGE2-treated cortical bone, compared to a negative bone balance in control bones. Collectively our data suggest that in vivo PGE2 is a powerful activator of cancellous and cortical bone formation, which may be able to build a peak bone mass to prevent and/or correct the skeletal defects to cure osteoporosis.

Alkaline Phosphatase↗
PubMed1990

[The effects of angiotensin II and other noradrenergic vasoconstrictors on the blood flow in Yoshida rat ascites hepatoma AH 109 A at same electrode position].

The differing effects of angiotensin II (AT II) and five other vasoactive agents on the tissue blood flow in Yoshida rat ascites hepatoma AH 109 A were studied at the same electrode position by a hydrogen clearance method. The elevation of blood pressure by AT II resulted in a 3.4-fold increases in the tumor blood flow. However, when AT II was reinfused, it resulted in only 2.1, 2.2, 2.3, 1.9 and 2.4-fold increases, respectively, after infusion of methoxamine, norepinephrine, metaraminol, epinephrine, and phenylephrine. A pronounced reduction and further reducing tendency in the tumor blood flow were found after administration of norepinephrine and epinephrine. In addition, metaraminol, phenylephrine, and methoxamine did not change significantly the blood flow of the tumor. The results of this present blood flow study further suggest that AT II acts more peripherally in the host vascular bed from which newly growing tumor vessels bud than other vasoconstrictors do.

Adrenergic Agonists↗
PubMed1990

Diarrhoea surveillance in children aged under 5 years in a rural area of Hebei Province, China.

A surveillance of diarrhoeal diseases in children aged under five years was carried out from March 1986 to February 1987 in a rural area of Hebei Province, China. Using a cluster sampling method, 270 study children were selected from 30 villages to represent a population of 105,405. Parents noted episodes of diarrhoea in children on a calender using a given definition of diarrhoea. The findings were verified by trained village doctors and were recorded monthly in the county Health and Anti-epidemic Stations. Stools of diarrhoea-affected children were examined to detect causal agents of diarrhoea, once in each of four seasons of the year. Of the 270 children, 218 (80.74%) suffered from one or more than one attacks of diarrhoea with a 95% confidence interval between 75.94% and 85.54%. There was no death due to diarrhoea. The diarrhoeal incidence in children of 3-4-year age group was significantly less than that in the children of less than 3 years (p less than 0.05). In the children with diarrhoea, the number of mean episodes was 3.15 per child/year, and the total mean course of suffering was 14 days per child/year. The ratio of diarrhoeal episodes in spring, summer, autumn, and winter was about 2.5:5:2:1. July was the month of highest occurrence of diarrhoea (146; 21.28% of all episodes). The epidemiological parameters of the disease declined with the growing age of the children, and there was no gender-specific preponderance in the number of episodes. During the whole year, 21.7% of the diarrhoeal episodes were due to bacterial pathogens, 4% of the episodes were due to rotavirus, and 3.65% episodes were associated with the detection of Trichomonas hominis.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1990

[Pathoanatomical and pathophysiological study of lung injury induced by activated complement in rat].

Acute lung injury induced by intravenous infusion of zymosan-activated plasma(ZAP) on Wistar rats was studied. A single infusion of ZAP resulted in an early occurrence of increased respiratory rate, decreased PaO2, elevated activity of superoxide dismutase(SOD) in the arterial blood and lung tissue. The results showed that the content of copperzinic superoxide dismutase(Cu Zn SOD) in bronchiolar columnar epithelial cells was elevated. Histological and electron microscopic examination showed that there was an accumulation of neutrophils in pulmonary microvessels and capillaries, endothelial cell and epithelial cell injury, and pulmonary edema etc. The tight junctions both in the epithelium and endothelium showed alterations in substructure including discontinuity, irregularity, free ends and distention of meshes as early as 2 to 4 h. In later stage, the severity of damage of tight junctions increased, while the number of strands in endothelial junctions reduced. All the parameters in the control group did not change significantly. From the results, the authors consider that acute lung injury is intimately related to the neutrophils and oxygen free radicals, the pathological basis of early pulmonary edema is alterations in the tight junctions of the alveolar epithelium and capillary endothelium.

Animals↗
PubMed1990

[Immunohistochemical study of folliculo-stellate cells in human adenohypophysis and in pituitary adenomas].

Significance of the appearance of folliculo-stellate cells (FSC) was studied in 59 human adenohypophyses and 58 pituitary adenomas after being stained with anti-S100 protein and 6 anti-pituitary hormone antibodies. S100 protein positive cells, stellate in shape with expending cytoplasmic processes among endocrine cells (EC) appeared in all the human adenohypophyses and had a tendency to be clustered in small groups characterized by gathering of 3 to 5 cells in the alveoli. Age or sex difference seemed to have no influence on the distributive density of FSC. FSC in the pituitary adenomas may be derived from two origins. One was the residue of normal pituitary tissue left in adenomas, and the other one seemed to be the chief component of the tumor, known as folliculo-stellate cell adenoma.

Adenoma↗
PubMed1990

[The investigation of the total amount of fluoride intake with correlative dental fluorosis polluted by burn coal in the epidemic fluorosis districts].

By means of the investigation in the five different townships with contrasting of the others, the main sources of fluorosis were found from pollution of the coal smoke, the content and total amount of fluoride intake from the maize and capsicum were calculated to be 74.35-94.72% by drying of the heat of burn coal and increased with the total amount of fluoride intake. The clear doses of the prevalence rates of dental fluorosis, the mean output of urinary fluoride and the total amount of fluoride intake--response relationship, showing a semilogarithmic positive correlation between 8 and 15 years of age. At the age the prevalence rates of bad incomplete teeth and milk-teeth showed a linear correlation with the total amount of fluoride intake and the mean output of urinary fluoride respectively. And seven regression equations were calculated. The question concerning the epidemic fluorosis districts caused by burn coal was discussed. We suggest that sick districts can be affirmed on the basis of the total amount of fluoride intake, the prevalence rates of dental fluorosis, bad incomplete teeth, milk-teeth and the mean output of urinary fluoride between 8 and 15 years of age.

Adolescent↗
PubMed1989

Flurbiprofen enhances growth and cancellous and cortical bone accumulation in rapidly growing long bones.

The effects of flurbiprofen, a non-steroidal anti-inflammatory drug, on bone growth was studied by static and dynamic histomorphometry in immature (28 days old) male Sprague-Dawley rats. Flurbiprofen at 0, 0.02, 0.1, 0.5 or 2.5 mg/kg/d doses was given subcutaneously daily for 21 days. The 0.1 and 0.5 mg/kg/d doses were most effective in stimulating longitudinal and radial bone growth and enhancing the accumulation of cancellous and cortical bone. Proximal tibial longitudinal bone growth rate, growth plate thickness, and periosteal bone formation rate were increased 30-40%, while cortical bone (tibial shaft) and cancellous bone (proximal tibial metaphysis) accumulated 12% and 90% more bone than controls, respectively. Enhanced accumulation of cortical bone was attributed to stimulated periosteal bone formation without accompanying marrow cavity enlargement. Enhanced accumulation of cancellous hard tissue was postulated to be due to reduced trabecular bone resorption and no effect on bone formation. The cell counts support these conclusions. There was a decrease in osteoclast numbers (-62 to -70%), an insignificant decrease in osteoblast numbers (-5 to -30%) per mm of bone surface and a decrease in osteoclast to osteoblast ratio (-35 to -56%). The findings presented are compatible with the conclusion that flurbiprofen, induced changes in rapidly growing long bones by reducing osteoclast activity and recruitment, stimulating longitudinal and radial growth, increasing the cortical bone mass by stimulated periosteal bone growth and depressed endosteal resorption, and increasing cancellous bone mass by depressed trabecular bone resorption without affecting bone formation.

Animals↗
PubMed1989

[Pharmacognostic studies on the Chinese drug guanzhong produced in East China].

By on-the-spot investigation we have checked up on 8 kinds of botanical origin of the Chinese traditional drug Guanzhong produced in East China and have given keys for their identification. The major tissue features of basal petioles and the external characteristics of the crude drugs have also been given.

Medicine, Chinese Traditional↗
PubMed1989

Autoradiographic study of the attrition of migrating schistosomula in the skin of mice. I. Mice immunized with highly X-irradiated Schistosoma mansoni cercariae.

The migratory pattern in naive mice of Schistosoma mansoni cercariae X-irradiated with OkR, 12kR, or 48rR has been investigated with compressed organ autoradiography. Three groups of 69 mice each were infected with 75Se-labelled cercariae. The skin at the site of infection, as well as the entire lungs and liver were removed from infected mice daily from 1-21d, on 24d, and on 28d; tissues were then processed for autoradiography. Autoradiographic analysis of migratory patterns showed that the schistosomula derived from nonattenuated cercariae passed quickly from the skin to the lungs and at a moderate rate from the lungs to the liver. Schistosomula derived from 12kR-irradiated cercariae were delayed in passing from the skin to the lungs and from the lungs to the liver, so that many remained in the lungs and died there, while only a few died in the skin or liver. Schistosomula derived from 48kR-irradiated cercariae remained mainly in the skin, rarely reached the lungs and were never found in the liver. This study indicates that immunization with 48kR-irradiated cercariae will cause no significant lesions in the lungs or liver.

Animals↗
PubMed1989

Prophylactic effects of m-nisoldipine and nisoldipine on reperfusion arrhythmias exacerbated by free radical generating system in Langendorff heart of rat.

Xanthine-xanthine oxidase (X-XOD, 500 mumol/L + 100 nmol/L) free radical generating system was perfused 10 min prior to coronary artery ligation until the end of the experiment. It exacerbated the reperfusion ventricular fibrillation, reduced the activities of superoxide dismutase and catalase and increased the contents of malondialdehyde in Langendorff heart of rats. m-Nisoldipine or nisoldipine (0.05 mumol/L) was perfused 10 min prior to coronary artery ligation until the end of the experiment. They prevented reperfusion arrhythmias exacerbated by X-XOD and decreased the free radicals generated by X-XOD.

Animals↗
PubMed1989

[A new drug delivery system in metastatic foci of cancer].

To improve the cancer chemotherapeutic effects on metastatic foci, we have developed a new drug delivery system based on two functional characteristics of the tumor vessels. Two functional characteristics of tumor vessel are summarized as follows: 1) A several-fold increase in tumor blood flow was brought about by angiotensin II-induced hypertension. The increase was selective and universal to the tumor vessels as long as the mean arterial blood pressure was kept under 150 mmHg. Such characterization was observed in micrometastatic foci. The concentration of anticancer drugs in tumor tissue could be increased by this function. Angiotensin-induced hypertension chemotherapy has been developed based on this characterization of tumor vessels. 2) Tumor blood flow almost decreased to zero when the mean arterial blood pressure was decreased to 60-65 mmHg by infusion of sodium nitroprusside. The stasis of tumor blood flow was also selective for the tumor tissues. The stasis suppressed a drug efflux from tumor tissues. By utilizing combination of these functional characteristics, we were able to enhance drug concentration X retention time in tumors remarkably. We named this drug delivery system "Flooding-the-castle chemotherapy". In these experiments, optimum blood pressures were kept under control by a computer system.

Angiotensin II↗
PubMed1988

Flurbiprofen-induced stimulation of periosteal bone formation and inhibition of bone resorption in older rats.

The skeletal effects of flurbiprofen (Fb), a nonsteroidal anti-inflammatory drug, was studied by histomorphometry in 9-month-old retired female breeder, Sprague-Dawley rats. Flurbiprofen was given subcutaneously at 0, 0.2, 0.1, 0.5, 2.5, or 5 mg/kg/d for 21 days. Flurbiprofen had no effect on longitudinal growth, but stimulated radial growth (+200%) over controls. In the tibial shaft, Fb stimulated the mineral apposition rate (+25%), mineral bone formation rate (+100%), and periosteal labeling length (+64%) at the 2.5 and 5.0 mg Fb/kg dose levels, and had no effect on marrow cavity size compared to controls. However, these changes were insufficient to increase cortical bone mass. In the proximal tibial metaphysis, Fb suppressed osteoclasts/mm2 of metaphyseal tissue (-47%), osteoclasts/mm of bone surface (-46%), and the osteoclast/osteoblast ratio (-50%), increased the calcified cartilage core population (+100%), and had no effect on osteoblast numbers at all dose levels. There was an insignificant increase in metaphyseal cancellous bone mass. The current study leads to the conclusion that flurbiprofen-stimulated periosteal bone growth was due to direct stimulation of osteoblast recruitment and activity independent of longitudinal bone growth. Further, it confirms early findings in young rats that flurbiprofen induced depressed bone resorption without lowering bone formation. However, because of insufficient treatment time, the older rat did not accumulate bone as the young rats did.

Age Factors↗
PubMed1988

Increased intratumor concentration of fluorescein-isothiocyanate-labeled neocarzinostatin in rats under angiotensin-induced hypertension.

On the basis of the observation that the tumor tissue blood flow selectively increases under angiotensin (AT)-induced hypertension, the change of the drug concentration in the tumor and normal tissues was examined in male Donryu rats. The intratumor concentration of fluorescein isothiocyanate-labeled neocarzinostatin was about 2-fold higher in the AT-induced hypertension group than in the control up to 20 min after the drug injection. In the normal organs or the uninvolved organs of the tumor-bearing rats, however, no clear increase was seen in the experimental group compared with the control, as anticipated from the observation of the tissue blood flow. The present study supports the hypothesis that the enhanced anticancer effect in chemotherapy under AT-induced hypertension formerly reported is due to the tumor-selective enhancement of the drug delivery.

Angiotensin II↗
PubMed1988

Study and clinical application of a porcine biomembrane for the repair of dural defects.

A biomembrane was developed from pig peritoneum treated with 0.65% glutaraldehyde. This was evaluated for use as a dural substitute in an animal model and in a patient population. After being treated with the glutaraldehyde solution, the biomembrane lost its antigenicity while its collagen underwent an irreversible cross-linking reaction, causing it to become a stable nonviable polymer resistant to absorption by the host. The biomembrane was used experimentally in 43 procedures on 20 dogs and was applied clinically in 614 patients. The results demonstrated that it is an acceptable material for the repair of dural defects, with the following advantages: 1) it is nontoxic to the body and brain tissues, with minimal tissue reaction; 2) its biophysical properties facilitate watertight closure with sutures; 3) its distensibility makes it suitable for decompressive surgical dural repair; and 4) its visceral surface is extremely smooth, causing virtually no adhesions with the brain tissue while the outer surface readily heals with the subcutaneous tissue.

Adolescent↗