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Biomedical subjects

L Liu

Publications and source records attributed to L Liu.

At least 1,135 records · Page 63Linked to original sources
PubMed1993

The rat renal nerves during development.

The prenatal and postnatal development of the innervation of the rat kidney has been investigated using immunocytochemical methods. The efferent innervation was studied using dopamine-beta-hydroxylase and neuropeptide Y antibodies. Calcitonin gene related peptide and substance P antibodies were used to investigate the afferent innervation. Kidneys from embryos of 14 to 20 days, from newborn rats, and from animals of 4, 10, 12, 21, 38, 60, and 90 days of age were studied. Slices of whole kidneys were analyzed, and frozen sections were used to investigate the location of the nerves in more detail. Both afferent and efferent nerves are observed inside the kidney by embryonic day 16. At birth, the afferent nerves are found (1) forming a rich plexus in the renal pelvis; (2) associated with the renal vasculature as far as the interlobular arteries (cortical radial arteries) and (3) in the corticomedullary connective tissue. The efferent innervation appears, at birth, to extend to the interlobular arteries and to the afferent arterioles of the perihilar juxtamedullary nephrons. The efferent innervation increases rapidly during the following days, and by postnatal day 21 a distribution of the innervation similar to that of the adult is observed. While the afferent innervation reaches the major target regions of the kidney by birth, the efferent does most of its expansion into the kidney postnatally. Afferent and efferent fibers are found, extrarenally and intrarenally, in the same nerve bundles. This proximity between afferent and efferent fibers may represent anatomical bases for their interaction in the adult as well as during development.

Afferent Pathways↗
PubMed1993

The renal nerves in the newborn rat.

Immunocytochemical methods were used to investigate the distribution of afferent [calcitonin gene-related peptide-(CGRP) immunoreactive and substance P-immunoreactive] nerves and efferent (neuropeptide Y-immunoreactive and dopamine beta-hydroxylase-immunoreactive) nerves in the kidneys of rats within the 1st day of life. The newborn rat kidney possesses an afferent and efferent innervation. Both afferent and efferent nerves reach the kidney in the same bundles. The afferent sensory fibers predominate overwhelmingly in the renal pelvis and ureter while the efferent fibers clearly predominate in the vasculature. The corticomedullary connective tissue contains both types of innervation with a more prominent afferent innervation (CGRP immunoreactive). Only afferent arterioles of perihilar nephrons were innervated by efferent sympathetic fibers. The distribution and extent of afferent and efferent innervation is consistent with the renal nerves playing a significant role in the transition from fetal to newborn life. The close proximity between afferent and efferent fibers suggests a possible interaction between the two systems.

Afferent Pathways↗
PubMed1993

In vitro cytochrome P450 monooxygenase and prostaglandin H-synthase mediated aflatoxin B1 biotransformation in guinea pig tissues: effects of beta-naphthoflavone treatment.

In the present study, we examined the effects of treating guinea pigs with beta-naphthoflavone (BNF) on aflatoxin B1 (AFB1) metabolism by microsomal cytochrome P450 monooxygenase (P450) and prostaglandin H synthase (PHS) in liver, lung and kidney tissues. After BNF treatment, microsomal 7-ethoxyresorufin O-deethylase activity was induced 13-, 25- and 11-fold in lung, kidney and liver, respectively, confirming that the BNF treatment protocol was effective at inducing monooxygenase activity. Treatment of guinea pigs with BNF did not change [3H]AFB1-DNA binding catalyzed by microsomal PHS or P450 in lung, kidney or liver. In contrast, AFM1 formation by P450 was significantly increased in microsomes from all three organs. The data indicate that BNF-inducible P450 isozymes of the P4501A class are responsible for the biotransformation of AFB1 to non-toxic metabolites. Guinea pig kidney microsomes could also catalyze NADPH-dependent formation of aflatoxicol (AFL), a metabolite usually produced by a cytosolic steroid dehydrogenase. Renal microsomal AFL formation was not altered by prior BNF treatment. The results in the present study suggest that BNF may alter the bioactivation of AFB1 in guinea pig tissues by inducing P450 activity, leading to the formation of less reactive metabolite.

Aflatoxin B1↗
PubMed1993

Calbindin-D28k gene expression in the developing mouse kidney.

Calbindin-D28k appears in the metanephric kidney during embryogenesis. We studied the temporal appearance and spatial distribution of calbindin-D28k mRNA in the developing kidneys of 12-day fetal through 21-day postnatal mice by in situ hybridization. 35S-UTP-labeled antisense (cRNA) probe to calbindin-D28k mRNA hybridized to the ureteric buds of 12-day embryos, whereas adjacent metanephrogenic tissue was unlabeled. By embryonic day 13, Y-shaped bodies of "advancing" ureteric buds were labeled intensely. In 16-day embryos, ampullae of ureteric buds were located immediately beneath the renal capsule and labeled strongly, in contrast to metanephric tubules and S-shaped bodies. The former were unlabeled and the latter were labeled only at points of contact with the ampullae. Subsequently, the ampullae of the metanephric ureteric buds hybridized with the cRNA probe, and from the 18th embryonic to the 21st postnatal day, this labeling was intense. The cRNA probe did not hybridize with the renal vesicles, proximal tubules, or tubular segments of Henle's loop derived from nephrogenic blastema, but it did label distal nephron segments. By the 21st postnatal day, collecting ducts and ureter no longer were labeled. In conclusion, calbindin-D28k mRNA is present in the developing mouse kidney, and its distribution during nephrogenesis is identical to that of calbindin-D28k per se. Collectively, these findings show that the calbindin-D28k gene is transcribed and its message is translated by the cells of the ureteric bud during the initial stage of renal morphogenesis.

Animals↗
PubMed1993

Dose-dependent ras mutation spectra in N-nitrosodiethylamine induced mouse liver tumors and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone induced mouse lung tumors.

In a previous study, the spectrum of H-ras mutations detected in B6C3F1 mouse liver tumors induced by 5, 50 or 150 mumol/kg body wt of N-nitrosodiethylamine (NDEA) was similar to that in spontaneous B6C3F1 mouse liver tumors, suggesting that activation of the H-ras gene in NDEA-induced mouse liver tumors may not be the direct result of the chemical interaction with the H-ras gene. In the present study, mutations in the H-ras oncogene from B6C3F1 mouse liver tumors induced by 5 or 50 mumol/kg body wt of NDEA were characterized by DNA amplification with polymerase chain reaction (PCR), single-strand conformation of polymorphism (SSCP) and direct sequence analysis. Twenty-one of 66 NDEA-induced B6C3F1 mouse liver tumors contained activated H-ras gene with 2 of 21 having a CG to AT transversion at the first base of codon 61, 17 of 21 having AT to GC transition and 2 of 21 having an AT to TA transversion at the second base of codon 61 in the H-ras gene. The predominant mutation, AT to GC transition (17/21, 81%) is consistent with the formation of O4-ethylthymine adduct, and is distinct from the predominant CG to AT transversion (50%) at the first base of codon 61 detected in H-ras gene from NDEA-induced B6C3F1 mouse liver tumors in a previous study by Stowers et al. Mutations in the K-ras oncogene from 59 A/J mouse lung tumors induced by 0.53 mmol/kg body wt of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were also characterized by using the above mentioned methods. Forty-six of 59 NNK-induced A/J mouse lung tumors contained activated K-ras genes. All 46 (100%) of the activated K-ras gene had GC to AT transitions at the second base of codon 12. The same mutation was observed in 70% (7/10) of the K-ras oncogene from A/J lung tumors induced by 4.8 mmol/kg body wt (given in 21 doses) of NNK. These data suggest that other factors in addition to genotoxic effect might be involved in the induction of rodent tumors by some carcinogens when given at higher doses. Therefore, further studies to compare the dose-dependent differences in the profile of ras mutations induced by chemical carcinogens may help to assess human cancer risk. Mutation(s) in exons 5-8 of the p53 gene was not found in these NDEA-induced mouse liver tumors and NNK-induced mouse lung tumors.

Animals↗
PubMed1993

Polymorphisms and rare sequence variants at the ROM1 locus.

Rom-1 is an integral membrane protein of the rod photoreceptor outer segment. The ROM1 gene is located on human chromosome 11q13, a region to which the loci of four degenerative retinopathies have been mapped. To identify alleles of ROM1, we have screened the DNA of 57 controls and 180 patients with inherited retinopathies. Six ROM1 polymorphisms were identified: two in non-coding sequences (C-7T, T insertion 966/967), two substitutions (Ala118Gly, Arg223Arg), and two RFLPs outside the transcription unit, detected with BcII and Hind III. One rare sequence variant (Arg229His) was found in two adRP probands; in the one family studied the allele was discordant with the disease. A second rare variant (Ala265Thr) was found in both an adRP family and a control; a third rare variant (Met271Thr) was present only in a control family. These polymorphisms will be useful in the evaluation of ROM1 as a candidate gene in inherited retinal diseases. The recognition of the rare variants will prevent their misassignment as disease-causing mutations.

Alleles↗
PubMed1993

Estrogen alters the effects of neuropeptide-Y on luteinizing hormone and follicle-stimulating hormone release in female rats at the level of the anterior pituitary gland.

In recent years, several studies have shown that neuropeptide-Y (NPY) is involved in the control of LH secretion. We determined the effects of estrogen on NPY-induced LH and FSH release in the absence or presence of LH-releasing hormone (LHRH) at the level of the anterior pituitary gland (APG). Adult female rats were ovariectomized. Fifteen to 20 days later, they were given a blank or estrogen-filled capsule subdermally and killed 17-19 h later. APG cells were isolated and cultured for 3 days in medium containing 12.5% rat serum collected at death from the same rats used to make the respective APG cell pools. The cells were then challenged for 3 h with vehicle, NPY (10(-12)-10(-6) M), LHRH (10(-9)-10(-6) M), or combinations of NPY (10(-9)-10(-7) M) and LHRH (10(-9) M). LHRH stimulated LH and FSH release from nonestrogen and estrogen-primed cells. NPY at 6.7 x 10(-8)-10(-6) M increased (P < 0.05) LH release and at 10(-6) M increased (P < 0.05) FSH release from estrogen-primed cells, but was without effect on nonestrogen-primed cells. In contrast, NPY at 10(-9)-10(-7) M potentiated the action of LHRH (10(-9) M) to increase the release of LH and FSH from nonestrogen-primed cells, but was without potentiating effects in cultures of estrogen-primed cells. The results demonstrate that 1) NPY can release LH and FSH by a direct action on estrogen-primed APG cells; and 2) NPY can potentiate the action of LHRH to increase the release of LH and FSH by a direct action on nonestrogen-primed APG cells.

Animals↗
PubMed1993

Elevated plasma levels of VWF:Ag in hyperthyroidism are mediated through beta-adrenergic receptors.

Thyroid dysfunction influences the levels of Von Willebrand factor (VWF:Ag). Plasma VWF:Ag levels in 35 hyperthyroid patients were significantly elevated, which had a positive correlation with both T3 (Triiodothyronine) and T4 (Thyroxine) levels. A follow-up study of seven hyperthyroid patients undergoing anti-thyroid therapy showed that the elevated VWF:Ag levels returned to normal range with the normalization of thyroid function. On the other hand, after administration of 160 mg/day of propranolol, a specific blocker of beta-adrenergic receptors, to five hyperthyroid patients for twenty-eight days, plasma VWF:Ag levels returned to normal range, while T3, T4 levels remained high without significant alteration. These results demonstrated that the elevation of plasma VWF:Ag by thyroid hormone is mediated through beta-adrenergic receptors, which may be useful to further understand the physiological and pathological roles of thyroid hormone in the regulation of VWF:Ag levels.

Adult↗
PubMed1993

Hypertension studies in China.

In China, hypertension (HT) prevalence increased from 7.7% in 1980 to over 11% in 1991. The higher prevalence of HT in the north and among urban populations may be due in part to higher body mass index (BMI) levels and dietary composition. Community control of HT has been organized since 1969. Reports from centers with a history of community control for over 10 years have indicated a 40% and 34% decrease respectively in the incidence of stroke and acute myocardial infarction (AMI). Sino-Monica Beijing Project shows that morbidity and mortality of stroke and coronary heart disease are higher in north China and urban centers, stroke is 4-8 times higher than coronary events. The trend from 1985-1989 was relatively steady. Although the mortality of stroke and AMI was decreasing, the case fatality rate remained high, and the rapid increase in the proportion of older population points to an urgent need for a nationwide prevention and control program.

Adolescent↗
PubMed1993

Diagnosis of active Paragonimus westermani infections with a monoclonal antibody-based antigen detection assay.

We evaluated the performance of Dot-enzyme-linked immunosorbent assays designed to detect species- and stage-specific antigens of Paragonimus westermani in sera with monoclonal antibodies as serodiagnostic tests for active paragonimiasis. Sera from all donors with parasitologically confirmed infections with P. westermani contained adult worm antigens, as did a high proportion of sera from persons suspected to be infected with this parasite. A smaller proportion of these sera also contained metacercarial stage-specific antigens. Sera from donors with other helminth infections, with confirmed pulmonary tuberculosis, or from healthy Chinese donors were nonreactive in the assay. Treatment of experimentally infected animals with praziquantel triggered a marked but transient increase in serum levels of adult P. westermani antigens, which then gradually disappeared within the next two months. The results of our studies indicate that the antigen-detection assay we have developed is a highly specific and sensitive diagnostic test for active infections with P. westermani.

Acute Disease↗
PubMed1993

[Effect of AMG-1 and adenosine on glutamate release from synaptosomes in rats].

The effects of AMG-1 [6(5-hydroxy-2-methylpyridylamino)-9 ribofranosylpurine], an adenosine analogue, and adenosine on Ca2+-dependent and independent release of glutamate from rat synaptosomes induced by KCl 30 mmol.L-1 were studied with an enzyme-linked fluorometric assay. The synaptosomes were prepared and preincubated for 30 min at 37 degrees C. Two ml of incubation mixture containing synaptosomes (1.27 mg protein), NADP+ 1 mmol.L-1, L-glutamic dehydrogenase 50 U, CaCl2 1.3 mmol.L-1 (or EGTA 1.3 mmol.L-1) was transferred to the stirred cuvette in the fluorometer at 37 degrees C for 5 min. Then, AMG-1 (or adenosine) was added. Released glutamate (eg. fluorescent intensity) was monitored following the addition of 30 mmol.L-1 KCl. The results indicate that Ca2+-dependent glutamate release from depolarized synaptosomes is inhibited by AMG-1 (0.1 mmol.L-1) or adenosine (0.3 mmol.L-1). The action of AMG-1 seems to be similar to that of adenosine. However, no change was found on Ca2+-independent release of glutamate. This implies that the protective effect of AMG-1 against cerebral ischemia may be partially due to inhibiting glutamate release from nerve terminal via the activation of adenosine A1 receptor.

Adenosine↗
PubMed1993

[Pleural malignant mesothelioma complicated with disseminated intravascular coagulation].

Three cases of MPM complicated with DIC were reported in a total of 6862 autopsies (0.04%) from 1950 to 1989 year in our university hospital. All the three cases showed hemorrhagic patches, shock, decreased platelets and fibrinogen, and prolonged prothrombin and thrombin time. Hyaline thrombosis was observed in the pulmonary interstitial microvessels. We have also discussed the diagnosis and pathogenesis of DIC.

Adult↗
PubMed1993

[Electrofusion of two-cell embryos of rabbit and their developmental capacity in vitro].

Optimal conditions of electrofusion for blastomeres of rabbit two-cell embryos to produce tetraploid embryos were investigated. The high fusion rate (68.9-100%), viability and developmental capacity to morulae and blastocyst (74.5%), which was similar to the development rate (79.3%) of fertilized ova in vitro, were obtained under a electro-field strength of 2.0 kV/cm with direct current(DC) pulse of 40 microseconds duration. A non-electrolyte solution (0.3 mol/L Mannitol+0.1 mmol/L CaCl2+0.01 mmol/L MgSO4) used as electrofusion medium was much better than an electrolyte solution (DPBS). Cytological study showed that 72.7% of embryos exposed to electrofusion treatment had tetraploid chromosome sets at morulae and blastocyst stages. The optimal electrofusion parameters used in this study can be used in the technique of nuclear transplantation in rabbit embryos.

Animals↗
PubMed1993

Income security in transition for the aged and children in the Soviet Union and in the Russian Federation.

A dynamic process of social security reform took place during the economic transition in the Soviet Union from 1985 through 1991, and in the Russian Federation in 1992. Despite administrative and financial difficulties, the Gorbachev reform objectives have been incorporated (with modest revisions) into the Russian Federation pension legislation and family allowance programs. Following the adoption of a radical economic reform policy in January 1992, policymakers in the Russian Federation have been hard pressed to meet rising social needs under severe fiscal constraints. As the number of the vulnerable population has increased, and as the emerging poor have had to face more severe hardships, the social security system has overcome unprecedented political and economic disruptions to become fully operational. Local governments and civic groups are organizing assistance to help meet needs where the State-operated programs have been inadequate. These efforts, however, have been made haphazardly.

Adolescent↗
PubMed1993

[Immune function of guifudihuang pills (GFDH) and their oral liquid preparation].

Experimental observation was made on the effect of GFDH pills and their oral liquid preparation on thymus and spleen weight, formation of the antibody haemolysis plaque and phagocytic function of the macrophages of peritoneal cavity. The result revealed that both GFDH pills and their oral liquid preparation were found helpful to the enhancement of immunological function. The oral liquid preparation also increased markedly the plasma level of testosterone in immature rats.

Animals↗
PubMed1993

[An immuno-pathological study of pterygium].

Pterygium specimens from 68 patients and normal conjunctiva from 12 controls were examined for the contents of immunoglobulins and C3 by direct immunofluorescence assay. The levels of IgE, IgG and IgA in the epithelial layer, of IgE, IgG and C3 in the basement membrane, and of IgE, IgG in the stroma, were found significantly higher in progressive cases than in the controls. as was the IgG-bearing cell count in the stroma. Also IgG bound to the basement membrane was significantly manifest in the quiescent cases. Routine histologic staining showed an infiltration of lymphocytes and plasma cells in the pterygium. A small amount of immunoglobulins was found in the stroma from the controls, but no C3 was demonstrated. These results suggest that an immunologic mechanism, possibly type I and type III hypersensitivity, may contribute to the pathogenesis of pterygium.

Complement C3↗
PubMed1993

[Studies on the descending projections from the pontine pneumotaxic region to the nucleus raphe magnus in cats].

Experiments were done on 23 pentobarbital anesthetized adult cats. 67 units recorded from the parabrachial and Kölliker-Fuse nuclear complex (NPBM-KF) could be antidromically activated by electrical stimulation of nucleus raphe magnus (NRM). Of the 67 units, 7 were respiratory related units (6 inspiratory, 1 expiratory). These comprise 8% of the 87 respiratory units examined. The antidromic latencies ranged from 0.4 to 2.5 ms. After injection of WGA-HRP (wheat germ agglutinin-conjugated horseradish peroxidase) into the NRM, many retrogradely labelled neurons were observed in the NPBM-KF. These results showed that neurons in the NPBM-KF sent axonal projections to the NRM, which may be involved in the control of respiration as well as nociception.

Animals↗