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Biomedical subjects

L Jin

Publications and source records attributed to L Jin.

At least 451 records · Page 25Linked to original sources
PubMed1989

Variances of the average numbers of nucleotide substitutions within and between populations.

Statistical methods for computing the variances of nucleotide diversity within populations and of nucleotide divergence between populations are developed. Both variances are computed by finding the phylogenetic relationships of the DNA sequences studied through the unweighted pair-group method or some other tree-making method. The methods developed are applicable to both DNA sequence and restriction-site map data.

Animals↗
PubMed1989

Estrogen stimulates both prolactin and growth hormone mRNAs expression in the MtT/F4 transplantable pituitary tumor.

The effects of 17 beta-estradiol (E2) on MtT/F4 pituitary tumor growth and on prolactin (PRL) and growth hormone mRNA expression were analyzed in F344 female rats. E2 (10 mg) stimulated pituitary PRL cell hyperplasia and PRL mRNA, but inhibited growth of the transplantable tumors. The expression of both PRL and growth hormone mRNA levels was increased in the MtT/F4 tumors. The effects of E2 on increasing PRL mRNA levels were more marked in the pituitary compared with the tumors. These results indicate that estrogens stimulate proliferation and PRL expression in the pituitary while inhibiting cell proliferation in the MtT/F4 tumor. E2 also stimulated both growth hormone and PRL mRNA expression in the MtT/F4 transplantable tumor.

Animals↗
PubMed1989

Calcium antagonists in prevention of hypertension and stroke in stroke-prone spontaneously hypertensive rats.

To investigate the effect of Calcium antagonists (Ca-An) with different tissue specificity in the development of hypertension and stroke in salt-loading SHRSP, three experiments were conducted. In experiment I (1), 50 8-week-old male SHRSP were divided into three groups and given nifedipine (NF, 32 mg/kg/day), menidipine (MN 32 mg/kg/day) and placebo (control group) respectively. In the control group 83.3% (15/18) died of stroke and 17 showed renal vascular sclerosis. Their average lifespan was 84 days. NF and MN significantly reduced systolic blood pressure (SBP), and no stroke of renal vascular sclerosis developed. In experiment I (2), 54 7-week-old male SHRSP were divided into three groups (18 in each group). They were treated with nimodipine (NM) 20 mg/kg/day, 2 mg/kg/day and placebo respectively. NM (20 mg/kg/day) markedly lowered SBP and postponed the onset of stroke. Only 11% died in 17 weeks. NM (2 mg/kg/day did not lower SBP but postpond the onset of stroke. In experiment II (1), 29 10-week-old female SHRSP were divided into three groups: Group A was given NF 32 mg/kg/day, group B was parathyroidectomized (PTX) and group C served as control. PTX group did not lower SBP but could postpone the onset of stroke. In experiment II (2), 33 male SHRSP were divided into three groups and ticated as described above in experiment II (1) (11 in each group). Seven weeks after the experiment, the brain blood flow of NF group was significantly greater (67.5%) than that of the control and PTX groups. In experiment III, 27 7-week-old male SHRSP were divided into three groups as described above in experiment I (2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The use of restriction fragment length polymorphisms for diagnosis: the estimation of diagnosable rate of more than one genetic markers].

As a codominant genetic marker, restriction fragment length polymorphisms, referred as RFLPs, has been widely applied to the prenatal diagnosis of some genetic diseases. To evaluate the usefulness of the genetic markers in prenatal diagnosis, a parameter, the diagnosable rate or the proportion of diagnosable matings is proposed in the cases of two or more genetic markers. The estimation is applicable to the cases of autosomal recessive and dominant disease, as well as those of X-linked recessive and dominant diseases. The diagnosable rate of two or more genetic markers is based on the distribution of haplotypes. Thus in the case when n genetic markers being used, the disagnosable rate, or the fraction of matings in which the A2A2 fetus could be confirmed or ruled out by the fetal restriction fragment patterns in the A1A2 X A1A2 matings, is expressed as follows: [formula: see text] where A2 is a recessive deleterious gene, yi is the frequency of the genotype of ith type individuals, and M is the total number of combination of n markers. It is a valuable strategy to use more than one genetic markers in order to increase the diagnosable rate. By using the data of the distribution of haplotypes, it is easy to find the most usable genetic markers or their combinations.

Genetic Diseases, Inborn↗
PubMed1989

[Platelet functions in patients with acute myocardial infarction].

The changes of platelet functions including platelet membrane microviscosity (PMMV), plasma 5-HT, plasma TXB2 and 6-K-PGF1a were studied in 30 cases of AMI and 13 cases of unstable angina (UA), 20 normal subjects as control. After onset of AMI, PMMV, plasma 5-HT, 6-k-PGF1a all increased quickly, especially on the 1st day (P less than 0.001-0.01). During 3 weeks observation, only 6-K-PGF1a decreased to the normal level on 14th day. There were no obvious decrease of plasma TXB2, 5-HT and PMMV. It showed that in acute phase of AMI without intervention of any antiplatelet drugs the platelets were activated continuously. Plasma 5-HT was the most sensitive predictor for the severity of AMI as observed by the comparison between the cases with complications and serum peak CK greater than 1000 U/L, and those without complications and peak CK less than 1000 U/L (P less than 0.001-0.05). The great change of PMMV was a bad prognosis. In patients with UA, during acute myocardial ischemia, the platelets were also activated significantly, but the extent was not as high as that in AMI.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Chromogranin A and B messenger ribonucleic acids in pituitary and other normal and neoplastic human endocrine tissues.

The distribution of the messenger ribonucleic acids (mRNAs) for chromogranin A and B was analyzed by in situ hybridization in normal and neoplastic endocrine tissues using frozen and paraffin tissue sections. Combined in situ hybridization and immunochemical staining was also done on tissue sections from the same cases using a monoclonal antibody against chromogranin A (LK2H10). Most endocrine tumors expressed chromogranin A and B mRNAs as well as chromogranin A protein. Normal pituitary expressed chromogranin A and B mRNAs and chromogranin A protein in the anterior pituitary gland. Most of these cells were gonadotropic hormone-producing cells. Prolactinomas (5/5) did not express chromogranin A mRNA or protein, but contained chromogranin B mRNA. Null cell or nonfunctional adenomas (8/8) expressed chromogranin A and B mRNAs and reacted with antibody LK2H10. In some tumors such as Merkel cell carcinomas, insulinomas, and parathyroid adenomas, a stronger signal for chromogranin A mRNA was detected than for the immunoreactive proteins. These results indicate that in situ hybridization complements immunochemical techniques in the analysis of endocrine cells and neoplasms. The gene products for chromogranin A and B are widely distributed in many endocrine cells and tumors, but some neoplasms such as prolactinomas have a differential distribution of chromogranin A and B mRNA and proteins.

Blotting, Northern↗
PubMed1989

Preoperative diagnosis and management of pheochromocytoma.

To improve the diagnosis and management of pheochromocytoma, the results from a comparative study of 34 patients with pheochromocytoma, 33 patients with essential hypertension and 36 normal volunteers are presented. Our data suggest that clinical characteristics indicate the possibility of pheochromocytoma only, while the definite diagnosis of pheochromocytoma must be based on comprehensive analysis of all data obtained from both clinical and laboratory studies. The plasma concentration of free norepinephrine in peripheral veins is helpful in establishing the presence or absence of pheochromocytoma. Both CT scan and meta-I-131-iodobenzylguanidine images are useful noninvasive techniques for localization of pheochromocytoma. Phenoxybenzamine is of benefit in both diagnosis and management of patients with pheochromocytoma.

Adolescent↗
PubMed1988

The use of restriction fragment length polymorphisms for prenatal diagnosis: the estimation of diagnosable rate of multiple genetic markers and its use in detecting beta-thalassemia in a Chinese population.

As a codominant genetic marker, restriction fragment length polymorphism (RFLP) has been widely applied to the prenatal diagnosis of some genetic diseases. To evaluate the usefulness of the genetic markers in prenatal diagnosis, a parameter, the diagnosable rate or the proportion of diagnosable matings, is estimated when two or more genetic markers are used. The assessment is based on the distribution of haplotypes. By using the data of the distribution of haplotypes of beta-A (normal) and beta-T (beta-thalassemia) chromosomes in a Chinese population and the formula given, it is easy to calculate the different diagnosable rates of all the combinations of seven given genetic markers. The results could help us to find an appropriate combination of genetic markers in prenatal diagnosis and, therefore, makes it possible to obtain a sufficiently high diagnosable value with a limited number of genetic markers.

China↗
PubMed1988

Significance of electrocardiographic isolated abnormal terminal P-wave force (left atrial abnormality). An echocardiographic and clinical correlation.

An abnormal terminal negative deflection in precordial lead V1 (PTFV1) is occasionally present as an isolated electrocardiographic finding. To determine the significance of this, 41 patients with PTFV1 greater than or equal to 0.04 mms were recalled for a repeated electrocardiogram as well as an echocardiographic examination. Patients were classified as cardiovascular normal (n = 15) or abnormal (n = 26). Left atrial enlargement was the most common echocardiographic abnormality found, but represented less than a third of the total. P-wave prolongation (greater than 110 ms) was present in 30 of the 41 patients and 21 of the 26 abnormal patients. This persisted into the second study, while the PTFV1 fell significantly in both the normal and abnormal groups. Among the P-wave abnormalities found, combinations were used to identify patients most likely to have cardiovascular disease. The most discriminating was an initial abnormal PTFV1 in combination with P-wave prolongation (sensitivity, 82%; specificity, 40%; positive predictive value, 70%; and negative predictive value, 55%). Maximal specificity (93%) and positive predictive value (88%) were achieved when P-wave prolongation and PTFV1 greater than or equal to 0.06 mms were present in both studies, although the sensitivity for this criterion was only 27%. The isolated P-wave abnormality described may be helpful in suggesting the presence of underlying cardiovascular disease and indicate the need for further evaluation.

Adult↗
PubMed1987

Variability of urinary sodium and potassium excretion in north Chinese men.

Variability of urine sodium (Na), potassium (K) and sodium/potassium (Na/K) excretion was studied in a sample of 50 employed normotensive male health professionals aged 27-50 in Beijing, China. Six 24-h urine specimens were collected from each participant during night-time (12-h) and daytime (12-h) fractions. The estimated ratio of intra- to inter-individual variances was 2.12 for night-time and 1.48 for 24-h urine Na, and 1.85 and 1.54, respectively, for urine K. Based on these values, six night-time and four 24-h urine specimens are necessary to reduce to 15% the diminution of a correlation between urine Na and another physiological variable. The corresponding numbers are five and four, respectively, for urinary K measurement. These data suggest that the ratio of within-person variation to between-person variation in Na excretion is smaller in these Chinese men than in Americans. The dietary Na intake of Chinese men can therefore be characterized with fewer urine specimens than are required for western populations. Night-time urinary Na and K showed good concordance with those from 24-h specimens in distinguishing high or low Na and K intake. These findings indicate that in large-scale epidemiological studies, overnight specimens may be adequate for classifying individuals with regard to Na and K intake.

Adult↗