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J Wands

Publications and source records attributed to J Wands.

18 recordsLinked to original sources
PubMed1992

Automated microparticle enzyme immunoassay for neural thread protein in cerebrospinal fluid from Alzheimer's disease patients.

An automated microparticle enzyme immunoassay (MEIA) with the IMx analyzer for the detection of neural thread protein (NTP) in cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients was developed. This assay uses monoclonal antibodies produced against the purified pancreatic form of the protein. The assay employs one monoclonal antibody covalently coupled to the microparticle to capture immunoreactive material in CSF or brain tissue. The second monoclonal antibody was conjugated to alkaline phosphatase and serves as detection antibody. The assay provides results in approximately 45 minutes with a sensitivity of 60 pg/ml (3 fmoles/ml). The titration curve of both normal and AD CSF resulted in a linear relationship with respect to the volume of CSF used. A similar relationship was observed when normal and AD brain tissue extracts were serially diluted. The molecular weight of NTP in CSF was approximately 20 kD as determined by gel filtration method under non-denaturing conditions. The recovery for pancreatic thread protein (PTP) spiked in either normal or AD CSF was 104% and 108%, respectively. Intra-, inter-, and total assay CVs (coefficient of variation) for controls were less than 2.9%, 3.3% and 3.0%, respectively. This assay will provide a useful tool in the study of the Alzheimer's disease and may help research in diagnosis and prognosis of Alzheimer's disease and related disorders.

Alzheimer Disease↗
PubMed1991

Selective G to T mutations of p53 gene in hepatocellular carcinoma from southern Africa.

Hepatocellular carcinoma (HCC) is a prevalent cancer in sub-Saharan Africa and eastern Asia. Hepatitis B virus and aflatoxins are risk factors for HCC, but the molecular mechanism of human hepatocellular carcinogenesis is largely unknown. Abnormalities in the structure and expression of the tumour-suppressor gene p53 are frequent in HCC cell lines, and allelic losses from chromosome 17p have been found in HCCs from China and Japan. Here we report on allelic deletions from chromosome 17p and mutations of the p53 gene found in 50% of primary HCCs from southern Africa. Four of five mutations detected were G----T substitutions, with clustering at codon 249. This mutation specificity could reflect exposure to a specific carcinogen, one candidate being aflatoxin B1 (ref. 7), a food contaminant in Africa, which is both a mutagen that induces G to T substitution and a liver-specific carcinogen.

Aflatoxins↗
PubMed1990

Polymerase chain reaction to detect hepatitis B virus DNA and RNA sequences in primary liver cancers from patients negative for hepatitis B surface antigen.

BACKGROUND AND METHODS: The role of hepatitis B virus (HBV) in the course of patients with primary liver cancer who are negative for hepatitis B surface antigen has been debated. We used the polymerase chain reaction to evaluate 28 such patients for the presence of DNA and RNA sequences of the virus; 22 of these patients had associated cirrhosis. The patients were from areas with different prevalences of HBV infection (South Africa, Italy, France, and Japan). RESULTS: Antibodies to the surface and core antigens of HBV were detected in 10 of the 23 patients tested. HBV DNA sequences were detected in 17 of the 28 patients, including 8 of the 10 with HBV antibodies and 6 of 13 without HBV serologic markers. HBV RNA molecules were found in four of five tumors tested. CONCLUSIONS: Our investigation indicates that transcriptionally active HBV genomes are present in various geographic areas among patients with liver cancer who are negative for hepatitis B surface antigen. This observation is consistent with an etiologic role for the virus in the development of these tumors.

Adult↗
PubMed1990

First-trimester maternal serum alpha-fetoprotein and human chorionic gonadotropin screening for chromosome defects.

The aim of this study was to determine the efficacy of combined maternal serum alpha-fetoprotein (MSAFP) and maternal serum human chorionic gonadotropin (MShCG) screening in detecting chromosome defects in the first trimester of pregnancy. Sera of 492 women (previously assayed for MSAFP) were analysed for MShCG under code without knowledge of cytogenetic results. Overall, 48 of 492 patients (9.8 per cent) had either an MSAFP multiple of the median less than or equal to 0.5 or an MShCG beta/alpha ratio multiple of the median less than or equal to 0.25, eight of whom had a fetus with a serious chromosome defect. A third of fetuses with Down's syndrome and 83 per cent with trisomy 18 were detected at a potential 'cost' of providing chorionic villus sampling or amniocentesis in 8.6 per cent of women screened.

Adult↗
PubMed1990

Enhanced expression of the protein kinase substrate p36 in human hepatocellular carcinoma.

A basic phosphoprotein defined by a monoclonal antibody named AF5 was found to be highly abundant in human hepatocellular carcinoma by Western immunoblotting. Under the same conditions, the levels of this phosphoprotein were low or undetectable in normal liver extracts. The AF5 antibody was used to screen a cDNA expression library of a human hepatoma cell line named FOCUS. A 960-base-pair cDNA was isolated and found to be a partial cDNA encoding the human protein-tyrosine kinase substrate p36, also known as lipocortin II. p36 expression was highly abundant in hepatocellular carcinomas at both the transcript and protein levels. Its expression was not induced significantly during rat liver regeneration following a partial hepatectomy. These results suggest that the induction of p36 expression is associated with malignant transformation of hepatocytes. p36 was previously shown to be phosphorylated upon transformation of normal fibroblasts by retroviral oncogenes without significant modulation of expression. We report here the initial description of the association of increased p36 expression with malignant transformation.

Antibodies, Monoclonal↗
PubMed1989

In vivo expression of two novel tumor-associated antigens and their use in immunolocalization of human hepatocellular carcinoma.

We are investigating the antigenic changes on the cell surface of human hepatocytes that distinguish the normal from the transformed phenotype using monoclonal antibodies. In vivo expression of antigens has been directly assessed by in situ radioimmunohistology. This technique allows one to determine the distribution and density of antigen expression at the individual cellular level on fresh hepatoma and adjacent uninvolved liver tissue. We have found two antigens recognized by monoclonal antibodies XF-8 and AF-20 that are uniformly present on 15/15 hepatocellular carcinomas tested thus far. Most if not all tumor cells highly express these antigens. Such antigens were not evident on adjacent normal liver and the XF-8 epitope was not found on other normal human tissues. AF-20 antigen distribution revealed low-level expression on a subpopulation of cells in the zona glomerulosa of the adrenal gland and on crypt cells of the small intestinal tract. We have studied the capability of radiolabeled XF-8 and AF-20 monoclonal antibodies when administered either alone or in combination to localize a hepatitis B virus-related hepatocellular carcinoma cell line (FOCUS) grown as subcutaneous tumors in nude mice. Biodistribution experiments demonstrated an excellent localization to tumor of 15 to 22% of the injected dose of 125I-labeled antibodies. Indeed, it was possible to enhance the delivery of 125I to the tumor cell surface by the use of XF-8 and AF-20 in combination. Nuclear imaging studies showed sharp visualization of tumor and demonstrate that these monoclonal antibodies have sufficient specificity and sensitivity to be strongly considered as immunotargeting agents.

Adenocarcinoma↗
PubMed1988

Transmission of hepatitis B from hepatitis-B-seronegative subjects.

The polymerase chain reaction (PCR) was used to identify and characterise serum HBV DNA sequences in 3 patients negative for all HBV serological markers. HBsAg determinants were detected in 1 individual by monoclonal anti-HBsAg immunoradiometric assay. By use of sets of primers on the S and pre-S parts of the HBV genome the presence of HBV DNA was demonstrated in the serum of all 3 patients. Inoculation of human sera to 2 chimpanzees induced acute hepatitis in both animals; 1 became positive for HBsAg and anti-HBcAg and the other only for anti-HBsAg. Cloning of DNA sequences from viral isolates from 1 chimpanzee and 1 patient was accomplished after amplification of the 3' region of the S gene. Comparison of the partial nucleotide sequence with that of known HBV subtypes showed 0 and 1 point mutation, respectively, in the highly conserved 3' end of the S gene. Therefore the results show that PCR with HBV primers may unambigously identify HBV infectious particles among non-A, non-B viruses and is a potentially useful diagnostic test for detection of HBV DNA sequences in serum.

Animals↗
PubMed1988

First-trimester maternal serum alpha-fetoprotein screening for chromosome defects.

Low maternal serum alpha-fetoprotein values during the second trimester of pregnancy are associated with an increased risk of Down syndrome in the fetus. In this study a sensitive, monoclonal-based radioimmunoassay for alpha-fetoprotein was used to determine whether such an association also applies to the first trimester and if maternal serum alpha-fetoprotein screening could successfully detect a significant number of pregnancies in which the fetus had a trisomy or other chromosome disorder. Sera were obtained prospectively from 540 women just before chorionic villus sampling for prenatal diagnosis of chromosome defects (largely because of advanced maternal age) at 8 to 12 weeks' fetal age and assayed for alpha-fetoprotein under code without knowledge of the cytogenetic results. Eight of 27 (29.6%) of all serious chromosome defects were associated with low maternal serum alpha-fetoprotein values (less than or equal to 0.6 multiples of the median). Overall, 59 of 540 patients (10.9%) had maternal serum alpha-fetoprotein values less than or equal to 0.6 multiples of the median, eight of whom had a fetus with a serious chromosome defect. Women whose maternal serum alpha-fetoprotein value was less than or equal to 0.6 multiples of the median had one in eight odds of carrying a fetus with a trisomy and one in seven odds of the fetus having any serious chromosome defect. From this study of a group of women at higher risk, we conclude that first-trimester maternal serum alpha-fetoprotein screening for chromosome defects is feasible. A prospective study to determine detection efficiency is now required of a consecutive routine pregnancy population in whom gestational age is determined by menstrual dates as is usually the case in clinical practice.

Chromosome Aberrations↗
PubMed1988

Physiological studies of human chorionic gonadotropin and free subunits in the amniotic fluid compartment compared to those in maternal serum.

We measured intact hCG, free alpha hCG, and free beta hCG levels in amniotic fluid and maternal serum using specific monoclonal antibody-based immunoradiometric assays. Compared to maternal serum, amniotic fluid had low levels of intact hormone along with high levels of its free subunits. The mean amniotic fluid hCG level was 1 mg/L at 13 weeks, and it progressively decreased to 0.100 mg/L by the 23rd week. Amniotic fluid alpha hCG levels were highest at 15 and 16 weeks (0.340 mg/L) and rapidly declined to concentrations less than 0.050 mg/L at 21 weeks. Amniotic fluid beta hCG concentrations were about 0.200 mg/L between 13 and 16 weeks and progressively decreased until the 23rd week. In vitro stability studies of hCG and its subunits demonstrated that dissociation of hCG into its subunits was not responsible for these results. Both hCG and free subunits detected in amniotic fluid were indistinguishable from standard hCG and free subunit preparations, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Our findings are consistent with the hypothesis that the presence of hCG and free subunits in the amniotic fluid represents secretion from the trophoblastic tissue into the amniotic fluid compartment. Furthermore, high serum hCG levels in association with low levels of its free subunits are probably the result of polarized secretion of the intact hormone from the syncytiotrophoblasts into the maternal circulation.

Amniotic Fluid↗
PubMed1987

Physiological studies of human chorionic gonadotropin (hCG), alpha hCG, and beta hCG as measured by specific monoclonal immunoradiometric assays.

Several libraries of monoclonal antibodies have been produced against epitopes that reside on hCG, alpha hCG, and beta hCG. Having characterized them physically, we explored their use in the construction of highly specific and sensitive immunoradiometric assays. There were several important immunochemical considerations with respect to developing assays that accurately detect low levels of free subunits in serum in the presence of high concentrations of the native hormone. These include physical properties and specificities of the monoclonal antibodies, choice of capture antibody on the solid phase support, assay design, and purity of hormone standards. Using such assays, we found early pregnancy (in vitro fertilization) to be characterized by the sequential appearance of hCG, followed by beta hCG and then alpha hCG. Molar ratios of beta hCG to alpha hCG and beta hCG to hCG were highest in early gestation. However, there was a reversal of the beta hCG to alpha hCG ratio at 12-13 weeks gestation, and an excess of free alpha hCG was observed thereafter. Except for values obtained in very early pregnancy, the beta hCG to hCG ratio remained remarkably constant at approximately 0.5% throughout gestation. In contrast, choriocarcinoma was distinguished by absolute serum beta hCG concentrations 3-100 times greater than the maximum values observed during pregnancy and, more importantly, by exceedingly high beta hCG to hCG ratios. For comparison, we studied hCG, alpha hCG, and beta hCG levels in an additional 178 patients with nontrophoblastic tumors. Ectopic production of alpha hCG and beta hCG was rare (3%), and thus far, we have been unable to demonstrate the presence of hCG in such patients. Therefore, hCG and the free subunits appear not to be useful as serological markers for nontrophoblastic tumors.

Adolescent↗
PubMed1987

Ectopic beta-human chorionic gonadotropin production by a human hepatoma cell line (FOCUS): isolation and immunochemical characterization.

We have established a human hepatocellular carcinoma cell line designed FOCUS that produces and secretes the beta-subunit of hCG. In the study of beta hCG production by FOCUS cells, we have developed and employed a series of monoclonal immunoradiometric assays (IRMAs) that detect epitopes unique to beta hCG, alpha hCG, hCG, and sequence-specific regions of the carboxyl-terminal peptide of beta hCG. The cells secrete approximately 15 ng beta hCG/10(6) cells and per 24 h; however, we were unable to detect either hCG or the alpha-subunit. The ectopic beta hCG was subsequently affinity purified from the culture medium and partially characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The mol wt of ectopic beta hCG was approximately 35,000 daltons. Immunochemical analysis of ectopic beta hCG by sequence-specific monoclonal antibodies revealed that epitopes corresponding to amino acid sequences 109-115, 121-145, 134-140, and 139-145 of the carboxyl-terminal peptide were present. FOCUS cells also demonstrate an intracytoplasmic localization of beta hCG by immunoperoxidase-staining techniques. Taken together, these findings suggest that FOCUS cells produce and secrete only beta hCG and that thus far, its physical properties appear indistinguishable from those of the native subunit. This unique cell line will be useful to study beta hCG gene(s) regulation as well as the mechanisms of ectopic beta hCG production and secretion.

Antibodies, Monoclonal↗
PubMed1986

Correlation of HBV DNA and monoclonal reactivity to HBsAg in serum of patients with HBV infection.

Hepatitis B virus (HBV) DNA hybridization assay, a monoclonal radioimmunoassay (M-RIA) for hepatitis B surface antigen (HBsAg) and conventional polyclonal immunoassays for HBV associated antigens were used to study sera from patients on dialysis and with acute hepatitis B. HBV DNA was detectable in hepatitis B e antigen (HBeAg) negative patients with acute hepatitis but not in HBsAg+ HBeAg- dialysis patients. In acute hepatitis, HBsAg immunoreactivity by M-RIA could still be detected even though a commercial immunoassay for HBsAg, the AUSRIA II, and the HBV DNA assay were no longer positive. Unlike in acute HBV infection, serum HBV DNA was detectable in dialysis patients who were AUSTRIA II negative but M-RIA positive. Serial determination of HBsAg by M-RIA and HBV DNA revealed episodes of HBV DNA positivity months after both the HBsAg was no longer positive by polyclonal immunoassay. Thus, the M-RIA for HBsAg and the molecular hybridization technique for HBV DNA are sensitive and specific assays for the identification of potentially infectious individuals who would not have been characterized as such based on the results of conventional polyclonal immunoassays.

Acute Disease↗
PubMed1985

Hepatitis B virus DNA in patients with chronic liver disease and negative tests for hepatitis B surface antigen.

We assessed the presence of hepatitis B virus (HBV) DNA in liver or serum samples from 134 patients with hepatitis B surface antigen (HBsAg)-negative chronic liver disease, including 20 with hepatocellular carcinoma. HBV DNA sequences were detected in 52 of the 88 liver samples (59 per cent), including 17 of the 20 samples from patients with hepatocellular carcinoma. Presumably "replicative forms" of HBV DNA were detected in only 5 of the 88 liver samples, 3 of which were from patients with no serologic marker for HBV. In most of the liver samples the DNA patterns were consistent with the presence of HBV or a closely related virus. Of the 105 serum samples tested, HBV DNA sequences were identified in 10 (9.5 per cent), 6 of which had no HBV serologic marker. Moreover, HBsAg-associated determinants were detected in 5 of 17 patients who were positive for HBV DNA and in none of 14 patients who were negative. This study demonstrates the high frequency of HBsAg-negative HBV DNA-positive viral infection of the liver and suggests that multiplication of HBV may occur in the absence of any conventional serologic marker for HBV.

Antibodies, Monoclonal↗
PubMed1979

Epithelioid cell cultures from rat small intestine. Characterization by morphologic and immunologic criteria.

Rat small intestinal epithelial cell lines have been established in vitro and subcultured serially for periods up to 6 mo. These cells have an epithelioid morphology, grow as monolayers of closely opposed polygonal cells, and during the logarithmic phase of growth have a population doubling time of 19--22 h. Ultrastructural studies revealed the presence of microvilli, tight junctions, an extensive Golgi complex, and the presence of extracellular amorphous material similar in appearance to isolated basement membrane. These cells exhibit a number of features characteristic of normal cells in culture; namely, a normal rat diploid karyotype, strong density inhibition of growth, lack of growth in soft agar, and a low plating efficiency when seeded at low density. They did not produce tumors when injected in syngeneic animals. Immunochemical studies were performed to determine their origin using antisera prepared against rat small intestinal crypt cell plasma membrane, brush border membrane of villus cells and isolated sucrase-isomaltase complex. Antigenic determinants specific for small intestinal epithelial (crypt and villus) cells were demonstrated on the surface of the epithelioid cells, but they lacked immunological determinants specific for differentiated villus cells. An antiserum specifically staining extracellular material surrounding the cells cultured in vitro demonstrated cross-reactivity to basement membrane in rat intestinal frozen sections. It is concluded that the cultured epithelioid cells have features of undifferentiated small intestinal crypt cells.

Animals↗
PubMedDate not supplied

Clinical significance of enhanced detection of HBsAg by a monoclonal radioimmunoassay.

We assessed the significance of the enhanced detection by monoclonal radioimmunoassay (M-RIA) of HBsAg in serum of patients with hepatitis B virus (HBV) infection. In acute HBV infection, the M-RIA detected HBsAg in the blood for a far longer period of time than previously recognized. In some patients, the "window phase" of HBV infection (defined as the presence of anti-HBc and the lack of detectable HBsAg and anti-HBs) was shortened or completely eliminated. Furthermore, 26% of individuals with anti-HBc as the only serologic marker of recent or past HBV infection were reactive only in the M-RIA. Analysis of patients tested for HBsAg because of suspected underlying liver disease revealed additional HBsAg-positive sera, unrecognized by polyvalent RIA, thus adding important information in the immunodiagnosis of HBV infection. The enhanced performance of the monoclonal RIA compared to conventional polyvalent RIA was due in part to the increased sensitivity of the assay and the observation that M-RIA may detect "hidden" HBV antigens in immune complexes.

Antibodies, Monoclonal↗