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Biomedical subjects

J Yan

Publications and source records attributed to J Yan.

At least 235 records · Page 13Linked to original sources
PubMed1996

[An experimental study on the treatment of fetal rabbits with intrauterine growth retardation].

OBJECTIVE: To investigate the effect of histocyte activators and vasodilators on the amino acids concentration in fetal rabbits with intrauterine growth retardation (IUGR). METHODS: The rabbits with IUGR were caused by passive smoking and treated with histocyte activators (adenosine triphosphatase, coenzyme A, cytochrome C, and vasodilators (injectio salviac molfiorrhizae composita, anisodamine). The effects of different remedies on the fetal plasma amino acids' concentration and the fetal development (i.e. birth weight, the weights of fetal liver and fetal brain) were studied. RESULTS: Both histocyte activators and vasodilators had favorable effects on the improvement of fetal development and the increase of fetal plasma amino acids' concentration. But the action of histocyte activators was stronger than vasodilators. CONCLUSIONS: The results suggested that vasodilators could improve the uterine-placental flow, and histocyte activators could enhance placental transfer of amino acids. But histocyte activators seem to be better than vasodilators.

Adenosine Triphosphate↗
PubMed1996

[Clinicopathological features of early colorectal carcinoma].

Five hundred and thirty-three cases (males 346, females 187; average age 58.9) of early colorectal carcinomas including 482 cases with single lesion and 51 cases with synchronous multiple lesions diagnosed at Cancer Institute Hospital in Japan from Jan. 1991 through June. 1995, were analyzed clinicopathologically. Early carcinomas accounted for 45.6% among all colorectal carcinomas. The total number of lesions was 622. Tumors were localized in the sigmoid colon in 42.8% of the 622 lesions and in 22.9% in the rectum. Macroscopically, 31.0% of the tumors were of pedunculated type and 29.3% was of subpedunculated type. With the growth of polyps, the frequency of malignant changes increased. Therefore, polyps should be considered as premalignant lesions and treated early.

Adenocarcinoma↗
PubMed1996

[Prevention from secondary nerve root adhesion: an experimental study].

In the study, 27 dogs were divided into three groups: A, B and C. Then all of the dogs had their lumbar intervertebral disks removed. Into the wounded cavity of group A, 1 ml of dimethicone was dropped and gelatin sponge was applied on the surface of the nerve root of group B. Group C was served as the control. The dogs were killed and the operation area was removed respectively 2 weeks, 4 weeks, and 12 weeks after the operation for macroscopical observation, nerve root motility measurement and histological examination. The result of the experiment proved that dimethicone was fairly effective in the prevention from secondary nerve root adhesion. While gelatin sponge in the process of its absorption induced the formation of quite a few scar tissues, thus aggrevating nerve root adhesion.

Animals↗
PubMed1995

Nature of G1/S cell cycle checkpoint defect in ataxia-telangiectasia.

We have previously demonstrated that cells from patients with ataxia-telangiectasia (A-T) fail to show initial delay at several cell cycle checkpoints post-irradiation. In addition a defect in the induction of p53 by ionizing radiation was evident. We demonstrate here that the radiation signal transduction pathway operating through p53, its target gene WAF1, cyclin-dependent kinases and the retinoblastoma (Rb) protein is defective in A-T cells. The defective p53 induction after ionizing radiation, observed previously in A-T cells, was also reflected at the functional level using p53-DNA binding activity, transactivation and transfection with wild type p53. Correction of the defect at the G1/S checkpoint was observed when wild type p53 was constitutively expressed in A-T cells. Exposure of control cells to radiation gave rise to p53 induction and as a consequence increased expression of WAF1 mRNA and protein, but A-T cells were defective in this response. As expected the WAF1 response in irradiated control cells resulted in an inhibition of cyclin-dependent kinase activity including cyclin E-cdk2, which plays an important role in the transition from G1 to S phase. No inhibition of cyclin-dependent kinase activity was observed in A-T cells correlating with the delayed WAF1 response. On the contrary an enhancement of cyclin-dependent kinase activity was seen in A-T cells post-irradiation. An accumulation of the hypophosphorylated form of Rb protein occurred in irradiated control cells compatible with the G1/S phase delay observed in these cells after exposure to radiation. In unirradiated A-T cells the amount of Rb protein was much higher compared to controls and it was mainly in the hyperphosphorylated (functionally inactive) form. In addition, accumulation of the hypophosphorylated form of Rb in A-T cells post-irradiation was defective, consistent with the lack of cell cycle arrest. Thus the failure of the G1/S checkpoint in A-T cells after exposure to ionizing radiation is consistent with a defective radiation signal transduction pathway operating through p53.

Ataxia Telangiectasia↗
PubMed1995

The largest variant of platelet glycoprotein Ib alpha has four tandem repeats of 13 amino acids in the macroglycopeptide region and a genetic linkage with methionine145.

Platelet membrane glycoprotein Ib alpha (GPIb alpha) bears the human platelet alloantigen (HPA)-2 and molecular weight (MW) polymorphisms on sodium dodecyl sulfate-polyacrylamide gels. HPA-2 arises from a threonine/methionine dimorphism at residue 145 of the GPIb alpha sequence, whereas different numbers of tandem repeats of a 39-bp sequence encoding 13-amino acids corresponding to a region between serine399 and threonine411 of the GPIb alpha account for the latter. To identify the genetic basis of the MW polymorphism among Japanese, we counted the tandem repeats in 103 individuals. In addition to the reported three variants with one, two, or three tandem repeats, we identified a new variant with four perfect tandem repeats of the 39-bp sequence that corresponded to the largest phenotype. Phenotypic analysis of the MW polymorphism on 12 individuals including all four phenotypes completely accorded in the genotype. We also determined the genotype of HPA-2 and found that methionine145 was in complete linkage disequilibrium, with the larger variants containing three or four tandem repeats. These results imply a model of evolutionary steps in the gene encoding GPIb alpha.

Alleles↗
PubMed1995

Absorption, tissue distribution and in vivo stability in rats of a hybrid antisense oligonucleotide following oral administration.

In vivo stability and oral bioavailability of an oligodeoxynucleotide phosphorothioate containing segments of 2'-O-methyloligoribonucleotide phosphorothioates at both the 3'- and 5'-ends (hybrid oligonucleotide) were studied. A 25-mer 35S-labeled hybrid oligonucleotide was administered to rats by gavage at a dose of 50 mg/kg body weight. HPLC analysis revealed that this hybrid oligonucleotide was stable in the gastrointestinal tract for up to 6 hr following oral administration. Radioactivity associated with the hybrid oligonucleotide was detectable in portal venous plasma, systemic plasma, various tissues, and urine. Intact hybrid oligonucleotide was detected, by HPLC analysis, in portal venous plasma, systemic plasma, and various tissues. The majority of the radioactivity in urine was associated with degradative products with lower molecular weights, but the intact form was also detected. In summary, the hybrid oligonucleotide was absorbed intact through the gastrointestinal tract, indicating the possibility of oral administration of oligonucleotides, a finding that may be important in the development of antisense oligonucleotides as therapeutic agents.

Administration, Oral↗
PubMed1995

Heterogeneity of rice ragged stunt oryzavirus genome segment 9 and its segregation by insect vector transmission.

Genomic heterogeneity of genome segment 9 (S9) of rice ragged stunt virus (RRSV) was investigated and a point mutation was found to be responsible for an electrophoretic mobility shift of S9 on polyacrylamide gel electrophoresis (PAGE). A new form of S9 (S9L) which migrated slightly faster than natural S9 (S9U) had the same length with A-->C transversion at nt 843. Synthetic S9 with a C:G pair at nt 843 migrated slightly faster than that with an A:U pair. Therefore, we conclude that the single point mutation shifts the electrophoretic mobility. Using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), we could detect S9U and S9L alone or mixture in insect vectors after acquisition as well as in infected rice plants.

Animals↗
PubMed1995

Pharmacokinetics of an anti-human immunodeficiency virus antisense oligodeoxynucleotide phosphorothioate (GEM 91) in HIV-infected subjects.

Human pharmacokinetics of an antisense oligodeoxynucleotide phosphorothioate (GEM 91) developed as an anti-human immunodeficiency virus (HIV) agent was carried out in this study. 35S-Labeled GEM 91 was administered to six HIV-infected individuals by means of 2-hour intravenous infusions at a dose of 0.1 mg/kg. Plasma disappearance curves for GEM 91-derived radioactivity could be described by the sum of two exponentials, with half-life values of 0.18 +/- 0.04 and 26.71 +/- 1.67 hours. The radioactivity in plasma was further evaluated by polyacrylamide gel electrophoresis, showing the presence of both intact GEM 91 and lower molecular weight metabolites. Urinary excretion represented the major pathway of elimination, with 49.15% +/- 6.80% of the administered dose excreted within 24 hours and 70.37% +/- 6.72% over 96 hours after dosing. The radioactivity in urine was associated with lower molecular weight metabolites. No drug-related toxicity was observed.

Adult↗
PubMed1995

Rice ragged stunt Oryzavirus genome segment 9 encodes a 38 600 Mr structural protein.

The complete nucleotide sequence of rice ragged stunt virus genome segment 9 (S9) was determined. The S9 segment is 1132 nucleotides long and has a long open reading frame starting from the first AUG codon at nucleotide position 14-16 and terminating at a UAG codon located at 1028-1030, which could encode a polypeptide with an Mr of 38 600 (P9). The encoded polypeptide has no sequence homology to polypeptides of any other plant reoviruses published previously. An immunological study demonstrated that P9 was the smallest of the structural proteins. The P9 polypeptide was expressed as a fusion protein with maltose binding protein in Escherichia coli. Antisera to purified virions and to the fusion protein reacted with both the bacterially expressed polypeptide and the smallest polypeptide of the purified virus in immunoblotting analyses.

Amino Acid Sequence↗
PubMed1995

[Observations on serum and amniotic fluid hormone levels and ultrastructure of uterine myometrium before and during term labor].

OBJECTIVES: To evaluate the relationship between serum and amniotic fluid (AF) estradiol (E2), estriol (E3), progesterone (Po), cortisol (Co), human placental lactogen (hPL) concentrations and uterine contractions. To observe the ultrastructural changes of uterine myometrium before and during labor. METHODS: Sixty-eight term-pregnant women (before labor 18, in normal labor 16, uterine inertia 34) were enrolled for study. Serum and AF E2, E3, Po, Co, hPL concentrations were measured by radioimmunoassay in 56 out of the 68 subjects. Myometrium gap junction (GJ), dense body (DB), sarcoplasmic reticulum (SR) were observed under electron microscope in the remaining 12 subjects (before labor 6, Uterine inertia 6). RESULTS: (1) E2, E3 levels and E2/Po, E3/Po ratio in AF, but not in serum, increased successively in the groups before labor, in normal labor and uterine inertia with significant differences (P < 0.01). (2) Both serum and AF Co, hPL concentrations were significantly different before and during labor (P < 0.01, P < 0.05). (3) Serum E2, E3, Co and hPL levels elevated significantly in cases with uterine inertia after successful treatment with estradiol benzoate or oxytocin infusion. (4) Compared with the group before labor, the amount of myometrium GJ, DB, SR increased significantly after the onset of labor. CONCLUSIONS: The elevation of serum and AF Co, hPL concentrations may be involved in the initiation of labor. This may be one of the major factors affecting the uterine contractions. Appropriate serum and AF estrogen (E), progestin (P), E/P ratio may be related to normality of uterine contractions during labor. The increase of GJ, DB, SR amount in uterine myometrium may be the histologic basis for the onset of labor.

Adult↗
PubMed1995

[The DNA damage by photodynamic effects of hematoporphyrin derivatives (HPD)].

Photodynamic effects of HPD has been used for cancer therapy (PDT) successfuly. The biological mechanism of the PDT was studied by using DNA as a target in this work. After treatment of phage M13 DNA with HPD + light the molecule of the DNA kept intact in TE buffer. But the smear bands by puting DNA in 0.1 mol/L NaOH at 90 degrees C and separating with electrophoresis denoted the degradation of DNA at the alkali-labile sites of phosphodiester bond in which the groups of the bases were photooxydized. The primer extension experiment showed the aggregation of DNA template by photooxydation. The DNA sequencing results showed that some of the wrong sequences appeared both at the site of A,G,C,T bases. The mouse Ehrlich ascetes carcinoma cell DNA was treated as above then degraded by Bgl II and BamH I respectively. It was found that the restriction fragments became larger than the controls. It also meant the alteration of the bases of DNA by the photooxydation. So the four bases of A,G,C,T of DNA were altered by photodynamic effects of HPD.

Animals↗
PubMed1995

Nonaccommodative factors of refractive accommodative esotropia.

The clinical characteristics of 45 cases of refractive accommodative esotropia were compared with 31 cases of the control group who remained orthotropic in the presence of uncorrected same degree of hypermetropia. In addition to the general ophthalmologic and orthoptic examinations, the accommodative convergence/accommodation (AC/A) ratio, fusional vergences and random dot stereopsis were investigated. The hypermetropic patients without esotropia were found to have a lower AC/A ratio and normal fusional function, while in cases with refractive accommodative esotropia, their AC/A ratios were normal and their fusional functions were decreased, especially significant being the divergent fusional function. In both groups, their stereopsis was defective or absent. It is suggested that esotropia be not simply caused by excessive accommodation due to uncorrected hypermetropia, and the range of divergent fusional function and the level of AC/A ratio be the two factors which determine the causation of esotropia in cases with uncorrected hypermetropia.

Accommodation, Ocular↗
PubMed1995

Superficial carcinomas of the esophagus and gastric cardia. A clinicopathological analysis of 141 cases.

From January 1970 to June 1992, 141 patients with superficial esophageal and cardiac carcinomas (SEC and SCC) underwent surgical treatment. Of the 141 patients 128(90.8%) had slight symptoms related to swallowing, and the remaining 13(9.2%) were asymptomatic. Balloon cytology and esophagoscopy proved very useful for the diagnosis of SEC and SCC, and Lugol's solution staining technique was an effective auxiliary diagnostic measure. Lymph node metastasis was not found in patients with epithelial (EP) cancer. However, it was present in one (2.9%) of 34 patients with muscularis mucosal (MM) invasion, and in 5 (8.6%) of 58 patients with submucosal (SM) cancer. The 5-year survival rates of the patients with SEC and SCC were 75.5% and 71.4%, respectively (P > 0.05). The different depth of tumor invasion including EP, MM and SM cancers showed significant differences in the 5-year survival rate (P < 0.05). Although the prognosis for the patients with lymph node metastasis is poor, we should advocate extended lymph node dissection in surgical treatment of the patients in whom MM and SM cancers are suspected.

Adenocarcinoma↗
PubMed1995

Preservation and observation of anterior ciliary vessels in rectus muscles during strabismus surgery.

PURPOSE: To observe the form and number of the anterior ciliary vessels (ACV) in rectus muscles. To train technician in preservation and observation of ACV, so preservation can be done in cases with a risk of anterior segment ischemia (ASI). METHODS: Curved foreign knife, iris hook, plastic rubber band and standard operating loupes (3x.) or microscope were used in the surgery on 34 cases of comitant strabismus and 18 cases of paralytic strabismus. RESULTS: The ACVs per muscle in medial, lateral, superior, inferior rectus were 3.08, 3.26, 3.50 and 3.50 respectively in 89 muscles of 52 surgical strabismus cases. All ACVs in 16 rectus muscles and 90 out of 220 ACVs in 73 rectus muscles were too small or too short to be dissected. The success rate of ACV preservation was 91.5% (119/130). 105 out of 130 vessels were saved using loupe magnification and 14 pit pf 130 vessels were saved under operating microscope. CONCLUSIONS: The number of ACV in rectus muscles are more than 2 in our observation cases. The ACV preservation has the clinical value of allowing us to perform muscle surgery on three or more rectus muscles simultaneously and get final surgical results more earlier after ACV in each muscle are dissected and preserved otherwise staged surgery are needed. The each strabismus surgeon must know this technique.

Adolescent↗
PubMed1995

[Clinical and experimental study on inhibitory effect of sanhuang mixture on platelet aggregation].

Sanhuang mixture (Xinmai capsule) is composed of Astragalus membranaceus, Coptis chinensis and Scutellaria baicalensis. It could inhibit platelet aggregation (PAG) induced by ADP in rats or by ADP and ADR in vivo. Patients with high PAG took Xinmai capsule for 4 weeks, the effective rate was 88.7%, which was same as the efficacy of aspirin 50 mg/day. In Syndrome Differentiation of TCM, the effective rate was the highest (92.3%) in the Syndrome of Qi Deficiency-Blood Stasis, and the lowest (72.7%) in the Syndrome of Stasis Phlegm and combined together.

Adult↗
PubMed1995

Brain mechanisms of satiety and taste in macaques.

Flavor is the primary reinforcer of eating. As satiety is induced, the reinforcement of flavor is lost. Since flavor derives largely from taste, one might expect gustatory responsiveness to decline with increasing satiety. However, no such loss of sensitivity occurs in humans, even as the reinforcing value of taste declines with satiety. Thus, we explored the effect of satiety on taste responses at several levels of the macaque's nervous system to determine where is influence began. Taste-evoked activity in the NTS and primary taste cortex was unaffected by the induction of satiety through or administration of glucose. Taste cortex projects to amygdala and orbitofrontal cortex (OFC). In amygdala, satiety reduced responsiveness by 58%; in OFC, neurons were fully suppressed. Both amygdala and OFC project to the hypothalamus, where taste responsiveness was also suppressed. Thus, the neural impact of food is reduced not in area devoted to quality analysis, but in those concerned with motivation and reinforcement.

Administration, Oral↗