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Biomedical subjects

S Chao

Publications and source records attributed to S Chao.

At least 73 records · Page 4Linked to original sources
PubMed1988

A tumor-associated antigen in carcinoma of the pancreas defined by monoclonal antibody B72.3.

A retrospective analysis of 25 primary adenocarcinomas of the pancreas, 16 metastatic pancreatic tumors, 8 cases of chronic pancreatitis, and 3 adult normal pancreas was performed to ascertain the reactivity of monoclonal antibody (MAb) B72.3 to malignant and nonneoplastic pancreatic lesions. Formalin-fixed, paraffin-embedded sections of pancreas were evaluated by immunohistochemical techniques (avidin-biotin-peroxidase complex [ABC] method). Twenty-one of 25 malignant primary tumors were reactive, and all 16 metastatic sites expressed the B72.3 antigen. In contrast, all cases of pancreatitis and normal pancreas were either weakly reactive or nonreactive. Ten malignant and two benign pancreatic fine-needle aspirates provided results similar to those seen with fixed tissues. Because MAb B72.3 has selective reactivity for primary and metastatic pancreatic cancer, it may be of value as a diagnostic adjunct in cytologic examination or for radioimmunodetection of regional and/or distant metastases of adenocarcinoma of the pancreas.

Adenocarcinoma↗
PubMed1988

Reactivity of the monoclonal antibody B72.3 with fetal antigen: correlation with expression of TAG-72 in human carcinomas.

The monoclonal antibody (MAb) B72.3 recognizes a mucin-like glycoprotein, TAG-72, which has been detected in a spectrum of human carcinomas, but not in the normal tissue counterparts. Using avidin-biotin-peroxidase complex (ABC) immunohistochemical techniques, MAb B72.3 was reacted with formalin-fixed, paraffin-embedded fetal and pediatric tissue sections to determine the extent of expression of the recognized antigen in these tissues. First trimester fetal tissues failed to express detectable antigen. Gastrointestinal epithelia from 13 to 34 weeks gestation demonstrated the most immunoreactivity with B72.3 although bronchial respiratory epithelium of the lung, transitional epithelium from the kidney, Hassall's corpuscles of the thymus, and gonadal tissues from fetuses of both sexes were also reactive. The TAG-72 antigen was not detected in fetal breast, pancreas, liver, spleen, adrenal, or heart. Expression of the TAG-72 antigen in malignancy appears to correlate well with fetal tissue reactivity with B72.3.

Antibodies, Monoclonal↗
PubMed1987

Growth and activity but not maturation are affected by perinatal diet.

Growth, maturation and activity in Sprague-Dawley rat offspring were studied as a function of two diets which were offered both pre- and postnatally. Day 1 gravid rats were placed ad lib on either Purina chow or Ensure, a total liquid diet. Half of each group was switched to the other diet on day 21 of gestation and maintained on it through weaning. Offspring remained on the same diet until sacrificed on postnatal day 60. Seven developmental measures were assessed daily until all of the animals reached criterion. The type of diet significantly affected maternal weight gain during the second third of gestation, and neonatal weight gain as measured on days 7, 14, 21, 28 and 45. Females were affected more than were male littermates. Males were significantly heavier than female littermates at all postnatal weighings. Diet had little or no effect on the developmental measures. Male/female differences were found for voluntary activity in the wheel which was measured on day 45. The use of liquid diets in behavioral teratology studies and the wisdom of using pellet diets as a control are discussed. The possibility of substituting careful measures of growth as an alternative to developmental testing is discussed.

Animal Nutritional Physiological Phenomena↗
PubMed1987

ras p21 expression in the progression of breast cancer.

The differential expression of the ras oncogene product p21 in the primary tumor, regional nodes, and distant metastatic sites in patients with disseminated breast cancer was examined to define the biologic and clinical significance of the ras oncogene in the progression of breast cancer. The avidin-biotin peroxidase complex method was used on formalin-fixed, paraffin-embedded tissues from 16 patients with metastatic disease. The primary antibody used in this protocol was RAP-5, an anti-p21 murine monoclonal IgG2a. p21 antigen staining was similar in the primary tumor and regional nodes from the same patient (P less than 0.05), but the staining of distant metastases was more variable. Expression of ras p21 was consistently increased in invasive components of the primary tumor as compared with intraductal tumor. In addition, a high level of p21 expression was seen in tumor emboli in lymphatics and blood vessels as compared with contiguous tumor in parenchymal tissue. Although p21 staining is present in aggressive primary breast cancers and most metastatic sites, our findings indicate that markedly enhanced p21 expression is associated with the earlier stages (invasion and dissemination) of aggressive breast cancers.

Breast Neoplasms↗
PubMed1987

The effect of lactation on ovulation and fertility.

It has long been recognized that women who breastfeed their children have a longer period of amenorrhea and infertility following delivery than do those women who do not breastfeed. The length of postpartum amenorrhea is quite variable, and depends on several factors, including maternal age and parity, and the duration and frequency of breastfeeding. In general, it would appear that the more frequent and the longer the episodes of breastfeeding, the longer will be the period of anovulation, and the longer the period of infertility.

Adult↗
PubMed1986

A comparison of tumor-related antigens in male and female breast cancer.

A retrospective analysis was undertaken in which 15 female and 15 male breast cancers were matched by age, stage, estrogen receptor status, and histologic type. Our protocol compares male and female breast cancers for reactivity with antibodies against tumor-associated antigens known to be present on female breast cancer cells. Formalin-fixed sections of each primary tumor were reacted in the ABC immunoperoxidase assay against antibodies B72.3 and DF.3 and an antibody to the ras p21 antigen. Reactivity to B72.3 and DF.3 was similar. However, the ras p21 antigen was expressed to a significantly greater extent in female breast cancers (p = .0008). Thus, although there are similarities in antigenic phenotype of male and female breast cancers, some female breast cancers may have a different pathogenesis as demonstrated by increased amounts of a specific oncogene product.

Adult↗
PubMed1986

Elevated ras oncogene expression correlates with lymph node metastases in breast cancer patients.

The protein product of the ras cellular oncogene(s) (p21) was assayed in primary breast carcinomas from two groups of patients who had different axillary lymph node status. Using an immunohistochemical assay, the intensity and percent of neoplastic cells demonstrating ras p21 antigen staining were significantly higher in the primary tumors from patients with lymph nodes positive (LN+) for malignancy (20 patients) compared with the lymph node negative (LNO) group (21 patients). The expression of p21 also correlated with tumor size. Age and estrogen receptor status did not influence p21 staining. The antigen expression of p21 was similar in intensity and distribution in the primary tumor and regional lymph node metastases. Enhanced expression of p21 in primary breast cancers that metastasize to regional nodes indicates that ras p21 may be a determinant of the malignant potential of breast cancer cells and may represent a new class of more biologically relevant tumor markers.

Antibodies, Monoclonal↗
PubMed1985

Maternal barbiturate administration and offspring response to shock.

Gravid Sprague-Dawley-derived rats were injected SC twice daily with either 20 or 40 mg/kg pentobarbital sodium (PT), sodium phenobarbital (PH), or the same volume of the saline vehicle on days 9-21 of pregnancy. Pair-feeding was employed. Vital, developmental, and activity measures were obtained on the neonates and locomotor activity was measured from 3-10 months of age. Avoidance was measured sequentially in a shuttle box, and in an operant chamber beginning at 3 months of age. The PH-80 dams gained less weight over the gestational period, and PH-80 and PH-40 offspring had more neonatal deaths. These male offspring were hyperactive at maturity, and PH-80 rats were initially slower to escape experimenter-initiated shock. PT exposure caused transient neonatal and juvenile hyperactivity. PT rats performed more poorly on both the conditioned avoidance and Sidman shock schedules, and had significantly lower brain: body weight ratios at 1 year of age. All four drug groups outperformed the saline offspring on subject-initiated shock schedules (punishment). Sex of offspring was determined on postnatal day 4 and the sex ratio was shifted towards male births with both drugs relative to controls.

Animals↗
PubMed1985

Aortic endothelial cell death and replication in normal and lipopolysaccharide-treated rats.

Endothelial cell death and replication was analyzed in the rat aorta with the use of combined IgG immunocytochemistry and 3H-thymidine autoradiography. Dead and replicating cells were clustered in the aortic endothelium of normal rats with a low level of spontaneous cell death and replication. Death and replication were also clustered in rats treated with endotoxin (Escherichia coli lipopolysaccharide [LPS]), a substance which is cytotoxic to endothelial cells in culture. LPS caused a dramatic increase both in endothelial cell death and replication, while no endothelial denudation could be discerned with the use of the 111In-labeled platelet technique. We conclude that endothelial cell death and replication are topographically clustered phenomena, which may imply that cell death leads to a local stimulation of cell replication. Furthermore, LPS induces a massive cell death, which is paralleled by cell replication, yet does not cause any significant increase in denudation. This suggests that the primary effect of LPS on the vessel wall is its cytotoxicity for endothelial cells. Endothelial cell death appears to provide the stimulus for cell replication both in normal and in LPS-treated rats.

Animals↗
PubMed1984

Nucleotide sequence and evolution of the 18S ribosomal RNA gene in maize mitochondria.

The nucleotide sequence of the gene coding for the 18S ribosomal RNA of maize mitochondria has been determined and a model for the secondary structure is proposed. Dot matrix analysis has been used to compare the extent and distribution of sequence similarities of the entire maize mitochondrial 18S rRNA sequence with that of 15 other small subunit rRNA sequences. The mitochondrial gene shows great similarity to the eubacterial sequences and to the maize chloroplast, and less similarity to mitochondrial rRNA genes in animals and fungi. We propose that this similarity is due to a slow rate of nucleotide divergence in plant mtDNA compared to the mtDNA of animals. Sequence comparisons indicate that the evolution of the maize mitochondrial 18S, chloroplast 16S and nuclear 17S ribosomal genes have been essentially independent, in spite of evidence for DNA transfer between organelles and the nucleus.

Animals↗
PubMed1984

Disseminated Kaposi's sarcoma in pregnancy: a manifestation of acquired immune deficiency syndrome.

The first case of acquired immune deficiency syndrome (AIDS) in pregnancy is reported. The patient, a drug addict, presented with lymphadenopathy, pulmonary infiltrates, and skin lesions of Kaposi's sarcoma, a tumor rarely found in young women in this country. The helper T-lymphocyte to suppressor T-lymphocyte ratio showed the profound inversion characteristic of this cell-mediated immune deficiency disease. Chemotherapy, a combination of doxorubicin, bleomycin, and vinblastine, was initiated during pregnancy. A growth-retarded infant was delivered vaginally. At four months of life, the infant had no apparent evidence of immune deficiency. Transplacental transmission of AIDS has not, as yet, been demonstrated. The social factors, clinical and laboratory features, and the controversies surrounding this new disease are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1981

Premature rupture of membranes, preterm delivery, and group B streptococcal colonization of mothers.

In a prospective study of colonization with group B streptococci (GBS) among 6,706 parturients, we found statistically increased incidences of premature rupture of membranes (PROM) and preterm delivery at less than 32 weeks' gestation among women colonized with GBS. PROM occurred in 8.1% of the total population but in 15.3% of the colonized population (p less than 0.005). Preterm delivery at less than 32 weeks' gestation occurred in 1.8% of the total population but among 5.4% of women colonized with GBS (p less than 0.005). The data suggest a causal relationship between GBS colonization and events leading to preterm birth. The possible impact of eradication of colonization with GBS on prematurity is considered.

Female↗
PubMed1978

Maternal ABO blood group type B: a risk factor in the developement of neonatal group B streptococcal disease.

In a prospective study of maternal genital colonization with group B streptococci (GBS) at the time of delivery, epidemiological data, including blood type (ABO group), were recorded for the 1,062 patients studied. Blood type B was found in a statistically significant higher proportion of patients colonized with GBS (28%) compared with the total population (16.4%) (P less than .005, X2 = 8.43). Women with blood type B were twice as likely to be colonized as those with types O or A. Hypotheses to explain this observation include the possibilities that GBS possess a B-like antigen, rendering parturients who lack anti-B antibody at increased risk for GBS colonization, or that GBS possess a receptor site for B surface antigens. One may speculate that a mutation toward an affinity for the human ABO blood group type B accounts for the advent of the group B Streptococcus as a significant perinatal pathogen.

ABO Blood-Group System↗