Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 307 records · Page 17Linked to original sources

PubMed1994

Role of charge and hydration in effects of polysialic acid on molecular interactions on and between cell membranes.

Previous studies have shown that the polysialic acid (PSA) moiety associated with the neural cell adhesion molecule (NCAM) has strong antiadhesive properties that can influence a variety of cell-cell interactions. Based on the size and structure of this long linear homopolymer, we have proposed that the activity of PSA results from its physical properties. In the present study, the premise that the charge and hydration properties of PSA underlie its effects on membrane vesicle aggregation is investigated through the manipulation of ionic strength. The results establish that the antiadhesive properties of PSA are accentuated at low ionic strength, where charge and hydration cause expansion of the polymer size, and are absent at high ionic strengths, where the polymer size collapses. These large effects of PSA on aggregation were shown not to result from changes in the osmolarity of the solvent or from the relatively small effect of ionic strength on the intrinsic functional properties of the adhesion receptors. In addition to this influence on overall membrane-membrane interaction, PSA was found to have a highly localized and ionic strength-sensitive effect on the binding of monoclonal antibodies to NCAM. Together these results suggest that the charge and hydration properties of PSA can impede both molecular interactions between apposing membranes and more direct contact of NCAM with other proteins at the cell surface.

Animals↗

PubMed1994

Regulation of the expression of annexin VIII in acute promyelocytic leukemia.

Annexin VIII is a calcium-dependent phospholipid-binding protein previously identified as a blood anticoagulant based on in vitro studies. However, the physiologic function of annexin VIII remains unknown. In acute promyelocytic leukemia (APL) the annexin VIII gene is highly expressed, but its expression is undetectable in the blasts of other acute leukemias. In the present investigation, we showed using the APL-derived NB4 cell line that expression of the annexin VIII gene is regulated at the transcription level during induced differentiation by all-trans retinoic acid (ATRA). The half-life of the annexin VIII mRNA is about 5 to 6 hours, as determined by using actinomycin D as a transcription inhibitor. Analysis of the expression of annexin VIII protein in NB4 cells and in APL samples showed a consistent expression of a predominant 36-kD protein and a weak 72-kD protein. After ATRA-induced differentiation of NB4 cells, the annexin VIII protein level reduced gradually, but a detectable level persisted even after 4 days of induction. Because annexin VIII mRNA becomes undetectable after 48 hours of ATRA induction, this result indicates that annexin VIII is a relatively stable protein. A multiple tissue Northern blot analysis was performed, and we found that annexin VIII is normally expressed in the placenta and the lung. Cellular localization of the annexin VIII protein was determined by immunofluorescence staining and subcellular fractionation. These results indicated that annexin VIII is predominantly localized to the plasma membrane. The annexin VIII is neither an extracellular protein nor associated with the cell surface suggesting that it does not play a role in blood coagulation in vivo. The plasma membrane localization and its property as a phospholipase inhibitor suggests that annexin VIII may have a role in the signal transduction pathway in the APL cells.

Annexins↗

PubMed1994

Comparative epidemiology of selected midline congenital abnormalities.

We present comparative epidemiologic characteristics of five congenital abnormalities that have been suggested to result from midline abnormal developmental disturbances: esophageal atresia with or without tracheoesophageal fistula (EA/TEF), imperforate anus with or without fistula (IA/F), omphalocele (OM), bladder exstrophy (BE), and diaphragmatic hernia (DH). The purpose was to assess the extent of epidemiologic similarities among these five defects. Data were collected as part of a population-based case-control study of infants with these defects born to mothers residing in Maryland, Washington, D.C., or Northern Virginia from 1980 through 1987. The estimated annual birth prevalences (per 10,000 live births) and 95% confidence intervals (CI) of these five defects were 0.40 (0.26-0.61) for BE, 1.34 (1.08-1.67) for OM, 1.59 (1.29-1.95) for DH, 2.11 (1.76-2.53) for EA/TEF, and 2.97 (2.55-3.46) for IA/F. The birth prevalence of IA/F and DH increased between 1980 and 1987. In contrast to the other four defects, DH showed a significant male preponderance (rate ratio 1.57, 95% CI 1.03-2.47), a significant white excess (rate ratio white:other, 1.56, 95% CI 1.00-2.48), and a lower proportion of multiple associated defects (30% vs. 46-61%). We concluded from this study that the descriptive epidemiology of diaphragmatic hernia is different from that of the other four defects. This finding may imply differences in etiologic and pathogenetic mechanisms underlying DH.

Abnormalities, Multiple↗

PubMed1994

Ossifying fibromyxoid tumor of soft parts: a morphological and immunohistochemical study.

A case is presented of ossifying fibromyxoid tumor of soft parts (OFMTSP) which occurred in the left cheek of a 59 year old Chinese woman. Histologically, the tumor was located in the subcutis with a fibrous pseudocapsule that contained discontinuous rims of mature trabecular bone. The tumor cells were small, round to ovoid with a uniform, round nucleus and a pale or slightly eosinophilic cytoplasm. Most of the cells were arranged in a random manner, some in a vague lace-like pattern. Mitotic figures were extremely rare. The stroma appeared fibromyxoid with scattered foci of mucinous lakes. Immunohistochemically, most of the neoplastic cells displayed immunoreactivities for S-100 protein, S-100 protein alpha, vimentin and alpha-smooth muscle actin; many tumor cells were positive for desmin. The tumor also showed stromal immunoreactivity for type IV collagen and was negative for cytokeratins, epithelial membrane antigen, glial fibrillary acidic protein, neurofilaments, muscle-specific actin, Leu-7, myelin-basic protein, osteocalcin and melanoma-specific antigen. The immunophenotypes expressed by the present OFMTSP seem to reflect two lineages of neoplastic cell differentiation, that is of nerve sheath and of smooth muscle; at the present stage, it is premature to diagnose this lesion as either nerve sheath or smooth muscle tumor.

Cheek↗

PubMed1994

Mechanism of pain and cytoskeletal properties in angioleiomyomas: an immunohistochemical study.

Angioleiomyoma is a solitary subcutaneous tumor characterized by pain in about half of patients with this tumor, and the pathogenesis of this pain has been a cause of much debate. To clarify the mechanism of pain and cytoskeletal property of tumor cells, 50 angioleiomyomas were studied clinicopathologically and immunohistochemically. The tumors occurred preferentially on the extremities, particularly the lower leg (46%), and the female to male ratio was 1.9:1. They were classified into three histological subtypes: (i) solid (30 cases); (ii) venous (15 cases); and (iii) cavernous (five cases). The pain and/or tenderness were present in 26 out of 49 patients (52%), in which small nerve fibers immunoreactive for S-100 protein and PGP9.5 were identified within the capsule of 20 tumors (77%) and the tumor stroma of 18 (69%), irrespective of the histological subtypes. In 24 patients where the pain was absent or unknown, nerves were observed within the capsule of 19 tumors (79%) and tumor parenchyma of 10 (42%). Many cells in all 50 tumors were positive for alpha-smooth muscle actin, and a relatively large number of cells in many tumors were positive for vimentin, desmin and collagen type IV. Also, cytokeratin (CAM5.2) reactivity was scattered in a few cells of four tumors. From these findings, the peculiar pain of angioleiomyomas could be mediated by the nerve fibers especially located within the tumor parenchyma. Although the expression of intermediate filaments in angioleiomyomas was heterogeneous, the overall cytoskeletal features were of smooth muscle cell differentiation.

Adolescent↗

PubMed1994

Higher exercise performance and lower VO2max in Tibetan than Han residents at 4,700 m altitude.

To examine the hypothesis that the pathway of adaptation to high altitude in natives differs considerably from that in newcomers, we measured maximal O2 uptake (VO2max), minute ventilation, anaerobic threshold (AT), blood lactate, and blood gases during maximal exercise in 17 lifelong Tibetan residents and 14 acclimatized Han Chinese newcomers living at the altitude of 4,700 m. The two groups were similar in age, height, and weight, and the subjects were nonathletes. Although VO2max was significantly lower in the Tibetans than in the Hans (30.4 +/- 1.5 vs. 36.0 +/- 1.9 ml.min-1.kg-1 STPD; P < 0.05), at maximal exercise effort the exercise workload was greater (167.7 +/- 4.2 vs. 150.0 +/- 5.9 W; P < 0.05). The mean AT values (in % VO2max) in the Tibetan and Han subjects were 84.1 and 61.6%, respectively (P < 0.01). Minute ventilation at maximal exercise was significantly lower in the Tibetans than in the Hans (68.4 +/- 3.4 vs. 79.7 +/- 4.1 l/min BTPS; P < 0.05), whereas heart rate at maximal effort was equivalent in the two groups. The Tibetans showed lower blood lactate value than did the Hans both before and at the end of exercise. We conclude that the Tibetan natives have higher exercise performance and AT but lower VO2max and blood lactate concentration than do acclimatized Han newcomers. These results may reflect the effects of genetic or peripheral adaptation factors in the Tibetan natives.

Acclimatization↗

PubMed1994

Detection of AML1/ETO fusion transcript as a tool for diagnosing t(8;21) positive acute myelogenous leukemia.

The nonrandom chromosomal translocation t(8;21)(q22;q22) can be found frequently in acute myelogenous leukemia with maturation (AML-M2). The breakpoint of this translocation has been cloned and characterized, and fusion transcript AML1/ETO has been identified. Reverse transcription polymerase chain reaction (RT-PCR) can be used to amplify the breakpoint site of AML1/ETO in t(8;21)-positive AML-M2 patients. The chimeric transcript can be detected in all 16 (100%) t(8;21)-positive AML-M2 patients. In all samples, the size of the amplified DNA fragments and pattern of restriction digest were identical, indicating that the t(8;21) translocation breakpoint occurs within a single intron of the AML1 and ETO genes. Interestingly, this fusion transcript was also detected in one of 13 AML-M2 patients without the t(8;21) translocation, indicating that a masked translocation involving chromosomes 8 and 21, exists in AML. Minimal residual disease was detected by semi-nested RT-PCR in all four patients tested, who had been in complete remission for 12, 15, 34, and 52 months, respectively. These results indicate that RT-PCR amplification of the AML1/ETO fusion transcript is a powerful tool for diagnosing and monitoring minimal residual disease in AML-M2 patients.

Adolescent↗

PubMed1994

[Investigation on etiology of abnormal ratio of CD4/CD8 cells in allergic nasal mucosal epithelium].

The lymphocytes of nasal mucosal epithelium were separated and the phenotype number of CD3, CD4 and CD8 cells were identified with immunohistochemical staining under light microscope. The number was increased significantly in CD4 cells and decreased in CD8 cells of rats' nasal epithelium after stimulation with histamine. Abnormal ratio of CD4 and CD3 cells in the allergic nasal epithelium tended to be normal after treatment with H2 antagonist. The results of our investigation demonstrated that histamine might cause the number of CD4 and CD8 cells into disorder in allergic nasal mucosal epithelium and the H2 antagonist may be useful in the treatment of allergic rhinitis.

Adolescent↗

PubMed1994

[Sequence of light chain variable region gene of a monoclonal antibody to human hepatocarcinoma].

The isolation of the rearranged immunoglobulin genes from a hybridoma cell line, which is a prerequisite for the construction of a recombinant antibody, can easily be achieved by PCR. We have determined the nucleotide sequence of the variable region of L chain of a high affinity monoclonal antibody HAb27 directed to human hepatocarcinoma. Analysis of the nucleotide sequence of the light chain V region of HAb27 revealed that the V kappa sequence was 85% identical to germline V kappa Ox1 sequence.

Amino Acid Sequence↗

PubMed1994

[In vitro sensitivity of Plasmodium falciparum to mefloquine, quinine, amodiaquine, chloroquine, pyronaridine and sulfadoxine/pyrimethamine in south Yunnan].

The sensitivity of P. falciparum to mefloquine, quinine, amodiaquine, chloroquine, pyronaridine, and sulfadoxine/pyrimethamine (MEF, QNN, AMO, CHL, PYR, S/P) was tested using in vitro microtest in south Yunnan Province in 1992. The ID50 were 46, 480, 52, 150, 15 and 2 x 10(4)/25 x 10(2) nmol/L, respectively; ID95 were 160, 1,536, 292, 680, 60 and 24 x 10(5)/3 x 10(5) nmol/L, respectively. All the isolates (30) were sensitive to MEF and QNN; 100% (30/30) and 96.7% (29/30) isolates were found to be resistant to AMO and CHL, the cross-resistance rate was 100% to the two drugs. One of 5 isolates exhibited resistance to PYR. The results suggest that the P. falciparum was susceptible to MEF and QNN, but was resistant to AMO, CHL and S/P. CHL-resistant P. falciparum showed a marked cross-resistance to AMO, but not to MEF, QNN, and S/P; AMO-resistant P. falciparum exhibited cross-resistance to CHL, but not to MEF, QNN, and S/P.

Amodiaquine↗

PubMed1993

Detection of the AML1/ETO fusion transcript in the t(8;21) masked translocation in acute myelogenous leukemia.

The fusion transcript AML1/ETO was detected in the bone marrow of two t(8;21)-negative acute myelogenous leukemia (AML) patients by means of reverse transcription-polymerase chain reaction. This fusion transcript is identical to the one transcribed from the t(8;21) translocation base, as deduced from (a) the size and restriction pattern of the amplified DNA fragment and (b) the DNA sequence analysis of the fusion junction. We also showed that the ETO gene is highly expressed in these patients, much as it is in the t(8;21)-positive AML. Southern blot analysis showed rearrangement of the AML1 gene in one of the patients. Together, our results demonstrate that there is a masked t(8;21) translocation in AML that is not detectable by cytogenetic analysis but is able to transcribe an AML1/ETO fusion transcript similar to that transcribed in t(8;21)-positive AML-M2 patients.

Base Sequence↗

PubMed1993

Coordinate gene expression of five subclass histones and the putative transcription factors, HBP-1a and HBP-1b, of histone genes in wheat.

The expression of genes encoding five histones (H1, H2A, H2B, H3 and H4) and the putative transcription factors HBP-1a (17) and HBP-1b (c38) was examined during early germination and in various tissues of young wheat seedlings. The steady-state levels of core histone (H2A, H2B, H3 and H4) mRNAs were coordinately cell cycle-dependent and paralleled the rate of DNA synthesis during early germination, whereas the expression pattern of the linker histone (H1) genes differed. The five subclass histone genes were actively expressed in the meristematic tissues of young seedlings. Moreover, H1 genes were expressed in leaves that consist mostly of non-proliferating cells, in which core histone genes showed little expression. Quantitative alterations to the mRNAs of the putative transcription factors HBP-1a (17) and HBP-1b (c38) of wheat histone genes were similar to those of the core histone mRNAs, suggesting that both factors function in the cell cycle-dependent expression of wheat core histone genes.

Base Sequence↗

PubMed1993

Diagnosis of Helicobacter pylori infection by means of a polymerase chain reaction assay for gastric juice aspirates.

A polymerase chain reaction (PCR) assay for Helicobacter pylori was developed with use of primer sequences from the ureA structural gene coding for the small subunit of urease. The PCR amplification was 100% specific for H. pylori in tests with 40 stock isolates of this species and with 30 control organisms, including two species of urease-producing Helicobacter. Thirty-four dyspeptic patients were evaluated by culture and histologic assessment of antral biopsy samples as well as by PCR of gastric juice aspirates. In 26 of the 34 patients, infection with H. pylori was diagnosed by culture and histology. PCR correctly identified 25 of these 26 patients. All eight patients with negative cultures and histologic findings also had negative PCR results. In this group of patients, therefore, PCR had a sensitivity of 96% and a specificity of 100%. Thus PCR of gastric juice aspirates can be used to diagnose H. pylori infection. This information is important since gastric juice can be aspirated through a nasogastric tube without gastroduodenoscopy. In addition, since clinical samples can be collected at one institution and mailed to a laboratory at another without compromising the outcome of the test, diagnostic PCR is accessible even to those clinicians at whose institutions the technology required for the procedure is not available.

Adult↗

PubMed1993

[Amino acid analysis of retinal S-antigen and interphotoreceptor retinoid-binding protein].

Retinal S-antigen and interphotoreceptor retinoid-binding protein (IRBP) were purified by DEAE-Sephacel ionexchange chromatography and Con A Sepharose affinity chromatography. Amino acid analysis of the S-antigen and IRBP was carried out and compared with that presented by others. The possible reason for difference with regard to some amino acids and related problems were analyzed and discussed.

Amino Acids↗

PubMed1993

The innervation of intradermal nevi. On the nevus-axon relations.

In the study of the histogenesis of intradermal nevi, the nevus cell-Schwann cell relationship has been a matter of long debate. We have demonstrated a dense axonal supply in the intradermal nevi by protein gene product 9.5 (PGP 9.5) immunohistochemistry. There were small nerve bundles between nevus cell nests and numerous individual axons in the nests of all the intradermal nevi studied. The distribution of these axons was more dense in the deeper and middle portions than in the superficial portion of the nevi. The significance and morphogenesis of this rich axonal supply in the intradermal nevi remain obscure, but this nevic neurotropism suggests an intimate mutual interaction between nevus cells and axons: possibly, some activities of nevus cells stimulating axonal proliferation, or nevus cell migration into the preexisting nerves. The presence of the proliferated axons may have some influences upon Schwannian transformation of the nevus cells. The mode of contact between nevus cell and axon, the presence of true Schwann cells surrounding the proliferated axons and the demonstration of myelin structure should be investigated by further electron microscopic study.

Adult↗

PubMed1993

[Dig-DNA probe for etiologic diagnosis in tuberculosis patients].

We have detected the sputa DNA with nonradioactive probe which is labelled to the specific sequence DNA, 31bp-188bp, by dig-11-dUTP. It showed that both the Sensitivity and specificity are satisfactory. The positive rate of the 80 specimens are 56.25%, and the 30 positive specimens of sputum culture are all positive when detected by the Dig-DNA probe.

Base Sequence↗

PubMed1992

Genetic-epidemiologic study of omphalocele and gastroschisis: evidence for heterogeneity.

On the basis of clinical manifestations, epidemiologic characteristics, and the presence of additional malformations, omphalocele (OM) and gastroschisis (GA) are considered casually and pathogenetically distinct abdominal wall defects. More than 50% of infants with OM have additional defects, but only about 15% of those with GA do. To evaluate whether there is heterogeneity between isolated and multiply affected cases of OM and GA, we analyzed epidemiologic characteristics and familial risks of major defects for 82 OM and 81 GA cases drawn from a population-based study in the Maryland-Washington, DC-Northern Virginia area and born from 1980 through June 1987. We examined year of birth, sex, race, and maternal age distributions after stratifying the infants into isolated and multiple defect groups. We found significant differences in maternal age between cases with isolated OM and GA, but not between cases with GA or OM who had other defects. Using regressive logistic models, we analyzed familial aggregation of birth defects among relatives of infants with OM and GA. An autosomal recessive model of inheritance was found to be the most parsimonious explanation for the families of infants with isolated OM or GA. However, for families of infants with multiple defects, a sporadic or nongenetic model fit best. These findings are not only useful for estimating familial risk of major birth defects, but they also suggest further heterogeneity of infants with OM and GA according to the presence of other malformations.

Abdominal Muscles↗

PubMed1992

Highly conserved hexamer, octamer and nonamer motifs are positive cis-regulatory elements of the wheat histone H3 gene.

Base substitution mutations were introduced into the promoter region of the wheat histone H3 gene, and promoter activity was assayed in stably transformed sunflower calli or in wheat protoplasts transfected transiently. At least four positive regulatory elements, a hexamer motif (ACGTCA), two octamer(-like) motifs of a direct (CcCGGATC) and a reverse (aATCCGCG) form, and a nonamer motif (CATCCAACG) were identified within the -185 region of the H3 promoter. Analyses of the type I element (CCACGTCACCaATCCGCG) consisting of the hexamer and reverse-oriented octamer motifs, and which is conserved in other plant histone genes as well, predicted the presence of an octamer-binding protein(s).

Base Sequence↗