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Biomedical subjects

R Lai

Publications and source records attributed to R Lai.

At least 91 records · Page 5Linked to original sources
PubMed1996

[A clinicopathological study of small-cell esophageal carcinoma].

Small-cell esophageal carcinoma (SCEC) is not uncommon. From 1979 through 1994, 42 cases of SCEC were diagnosed among 711 patients with cancer of the esophagus, with a relative frequency of 5.9%. Differential diagnosis is difficult according to clinical symptoms and signs. However, SCEC differs greatly from squamous-cell carcinoma of the esophagus in histopathology and biologic behavior but is similar to small-cell lung cancer (SCLC). Surgical treatment alone of SCEC patients has a mean survival period of 11.2 months while patients treated with radiotherapy alone has a longer survival (22.8 months). No case was treated only with chemotherapy in this group of patients. Those received no treatment could survive 6.2 months only. Therefore, SCEC is a very aggressive tumor with poor prognosis. Histochemical and immunohistochemical study revealed both epithelial and neuro-endocrine differentiation potentials suggesting that SCEC probably originates from mulfipotential primitive stem cells in the esophageal mucosa.

Adult↗
PubMed1994

Psychological implications and acceptability of preimplantation diagnosis.

The aim of this study was to ascertain the degree of acceptability of preimplantation diagnosis with blastocentesis in 180 women at risk for beta-thalassaemia awaiting chorionic villus sampling (CVS). The women were asked to fill in a questionnaire some days before sampling. All women who had had previous therapeutic abortion found blastocentesis acceptable. Only 30% of women who had not had previous therapeutic abortion chose blastocentesis, whilst 25% of primigravid women opted for blastocentesis. From these preliminary data it seems that obstetric experience is an important factor in the reproductive choice of women at high genetic risk.

Adult↗
PubMed1994

Postnatal changes of CD45 expression in peripheral blood T and B cells.

One known postnatal change of CD45 expression is the decline of the CD45RAhigh CD45ROlow T subsets and the reciprocal increase of the CD45RAlow CD45ROhigh T subsets in the peripheral blood. Using a panel of monoclonal antibodies reactive with either protein or carbohydrate epitopes on the variable regions of CD45, we were able to detect more postnatal changes of CD45 expression. These changes are largely caused by modulation of the CD45 glycosylation, including: (1) lesser sialylation of the CD45RA region on T cells, and (2) differential sialylation of the CD45RB region leading to the distinction of CD45RBhigh and CD45RBlow T and B subsets. In addition, the existence of the CD45RAdim CD45ROdim labelled as transitional T cells is only found during the postnatal life. These changes may reflect the maturation of the immune system.

Adolescent↗
PubMed1993

Patterns of leucocyte common antigen expression in peripheral blood T cell populations.

The restricted forms of CD45 are differentially expressed on lymphocyte subsets in different maturation stages and with different functional activities. The best-known examples are the expression of CD45RA on naive and CD45RO on memory T cells. Multicolor flow cytometry allows for the analysis of lymphocyte subsets with respect to the expression of the various CD45R isoforms (RA, RB, RO). Here we report on the distribution of these isoforms in normal peripheral blood T cells, including the CD4, CD8, and CD56 subsets. The results indicate the presence of a number of consistent patterns within these subsets, which can be linked to populations with well-defined functional activities, and also identify several transitional stages and hitherto undefined subsets.

Antigens, CD↗
PubMed1993

Early transabdominal chorionic villus sampling in couples at high genetic risk.

OBJECTIVE: The purpose of the study was to evaluate the feasibility and safety of transabdominal chorionic villus sampling before 9 weeks' gestation. STUDY DESIGN: Two hundred pregnancies at risk for beta-thalassemia (n = 198) or Duchenne muscular dystrophy (n = 2) underwent transabdominal CVS at 6 through 8 weeks. Sampling success and fetal loss are expressed in percentages. RESULTS: Sampling was successful in all cases (100%). Forty-eight fetuses were affected by beta-thalassemia and one by Duchenne muscular dystrophy. The percentage of fetal loss, expressed as a proportion of continuing pregnancies, was 4.0%. All women (n = 144) have been delivered, and no misdiagnoses have occurred. We observed one anencephalus and one mild limb defect consisting of absence of distal phalanges of index and little fingers of both hands and distal phalanges of both little toes. CONCLUSION: Transabdominal CVS before 9 weeks is a reliable and relatively safe method for prenatal diagnosis in patients at high risk for genetic diseases. However, further studies are necessary to assess the risk to the fetus.

Adult↗
PubMed1993

[Effects of interfacial state and bonding on the biostrength of plat castable ceramics crown].

Plat castable ceramics (PCC) restorations depend primarily on their biostrength. In our experiment the human oral physiological environment was simulated and we studied the effects of restoration-tooth interfacial state and bonding on the biostrength of PCC crowns. The bond strength affects the biostrength of PCC crowns obviously. The interfacial treatment affects not only the bond strength between PCC crown and tooth structure but also the biostrength of the crown cemented.

Adhesives↗
PubMed1992

Transabdominal chorionic villus sampling: fetal loss rate in relation to maternal and gestational age.

In this paper we report the fetal loss rate in relation to both maternal and gestational age in 1764 pregnant women who underwent transabdominal chorionic villus sampling (TA-CVS) between January 1986 and August 1990. The fetal loss rate, considered as a proportion of continuing pregnancies, decreased with advancing gestational age at sampling from 4.3 per cent before 9 weeks to 0.4 per cent at or after 13 weeks, the difference being statistically significant (p < 0.025). The fetal loss rate increased from 1.6 per cent in women under 30 to 2.4 per cent in women of 40 years or over, but the difference was not statistically significant. Considering that the total fetal loss rate before 28 weeks' gestation was on average 1.91 per cent (1.3 per cent under 35 years and 2.8 per cent in women of 35 or over), we believe that TA-CVS is a safe and effective technique for prenatal diagnosis of genetic diseases.

Adult↗
PubMed1992

[Study on casting precision of plat castable ceramic crowns].

The plat castable ceramic crown was made with investment material prepared in our college with our own casting technique by a Chinese-made casting machine. The accuracy and fitness of the crown were studied and appraised. Results show that the margin of fitness is 46 microns and that the cement film thickness of the dies in the spacer material group is 65.13 microns. Hence the results are satisfactory. The Plat castable ceramic crown might be used in clinical dentistry.

Crowns↗
PubMed1991

Antibody MT3 is reactive with a novel exon B-associated 190-kDa sialic acid-dependent epitope of the leukocyte common antigen complex.

MT3 is a new antibody reactive with a restricted isoform of the leukocyte common Ag (CD45) family. The Ag is mainly expressed on T lymphocytes and thymocytes. It is differentially expressed on B cell subpopulations, with no staining of the majority of small follicular mantle zone B cells but positive staining of the majority of marginal zone B cells of spleen. Like most CD45 antibodies, reactivity can be demonstrated in fresh frozen as well as in formalin-fixed, paraffin-embedded tissues. This reactivity clearly differs from all other published anti-CD45 antibodies. In immunoprecipitation and Western blot procedures, the antibody reacts with a major band with a molecular mass of 190 kDa and weak bands with molecular masses of 205 and 220 kDa. Compared to antibody PD7 that reacts with exon B-encoded sequences, the reactivity with the 205 and 220 bands is much weaker. This is reflected in MT3 reactivity with leukocyte common Ag transfectants that include exon B-encoded sequences, such as AB and B, but not with those that also include C-encoded sequences, such as ABC or BC. It can be concluded that MT3 recognizes additional heterogeneity in the leukocyte common Ag complex, that is based on the differential expression of sialic acid-dependent determinants associated with exon B-encoded sequences.

Antibodies, Monoclonal↗
PubMed1991

Early antenatal sonographic diagnosis of conjoined syncephalus-craniothoraco-omphalopagus twins. Case report.

The paper describes the prenatal ultrasonographic diagnosis of conjoined syncephalus-craniothoraco-omphalopagus twins at 13 weeks' gestation. The mother, after genetic counseling, decided to interrupt the pregnancy. The fetal karyotype, the maternal serum and amniotic fluid alpha-fetoprotein levels were normal. The diagnosis was confirmed by pathologic examination of the fetus after termination of pregnancy.

Adult↗
PubMed1991

Tissue distribution of restricted leukocyte common antigens. A comprehensive study with protein- and carbohydrate-specific CD45R antibodies.

A panel of monoclonal antibodies, specific for either protein or carbohydrate components of the leukocyte common antigen (LCA), were used to characterize the expression pattern of different variants of this antigen complex. Immunohistochemical and flow cytometric analysis was carried out on human lymphoid tissues from different anatomical compartments. We found that variations in terminal sialic acid or O-linked sugar moieties were associated with drastic differences in reactivity with some of the CD45R antibodies. For example, the carbohydrate determinants recognized by MT2 (CD45RA) and 2B11 (CD45) were not or were very weakly expressed on germinal center cells, whereas the carbohydrate determinant recognized by MT3 (CD45RB) was not expressed on the majority of mantle zone B cells. On the other hand, KiB3 (CD45RA) reacted with a protein determinant that is normally only exposed on mantle zone B cells but can be uncovered on marginal zone B cells and the CD45RA-positive T-cell subpopulation by enzymatic treatment. The findings suggest that differential biosynthesis and expression of the carbohydrate components of LCA are important mechanisms to generate additional LCA heterogeneity. Similar to the differential usage of the variable region, the exact carbohydrate composition is also linked to the stage of cell development. Heterogeneity in carbohydrate composition of the extracellular domain of LCA appears to enable interactions with different ligands, thereby holding the key to the regulation of LCA cytoplasmic tyrosine phosphatase activity.

Antibodies↗
PubMed1991

Monoclonal antibody OPD4 is reactive with CD45RO, but differs from UCHL1 by the absence of monocyte reactivity.

Monoclonal antibody OPD4 was described as a novel monoclonal antibody recognizing a helper/inducer T-cell subset in paraffin-tissue sections. The authors have analyzed this reagent with respect to its molecular weight, reactivity with leukocyte common antigen (LCA) transfectants and cell and tissue distribution. OPD4 was found to be reactive with the 180 kd molecular weight isoform of the leukocyte common antigen family, similar to antibody UCHL1 and therefore can be considered as a CD45RO reagent. The only difference in distribution was found to be the absence of OPD4 reactivity with peripheral blood monocytes. Since OPD4 recognizes the same antigen on T cells as UCHL1, both reagents do not need applied in the immunophenotyping of lymphomas.

Animals↗
PubMed1989

Nucleotide sequence of the 3'-terminal region of clover yellow mosaic virus RNA.

The nucleotide sequence of the 3'-terminal region of clover yellow mosaic virus RNA determined from cDNA clones contains one major open reading frame (ORF) encoding a protein with an Mr of 28,093 (28.1 K). A smaller ORF, in frame with the major one, is also present and encodes a 23.5K protein which is similar in size to the capsid protein of the virus and has several sequence similarities with the coat proteins of four other potexviruses. The smaller ORF is probably used for the expression of the coat protein because the capsid subgenomic mRNA probably does not include the AUG of the 28.1K protein. Comparison of the amino acid sequences of the coat proteins of five potexviruses revealed a large number of identical and conservative replacements of amino acid residues.

Amino Acid Sequence↗