Biomedical subjects

M Loda

Publications and source records attributed to M Loda.

At least 91 records · Page 5Linked to original sources

PubMed1995

Thrombopoietin receptor expression in human cancer cell lines and primary tissues.

c-mpl is the receptor for the recently identified megakaryocyte growth and differentiation factor thrombopoietin. Thrombopoietin has been shown to be capable of raising platelet counts in animals and is about to enter clinical trials in humans. In anticipation of its likely use in the care of patients receiving cancer chemotherapy, we evaluated the expression of human c-mpl by reverse transcription PCR on 39 human cell lines and 20 primary human tissue samples derived from both normal and malignant sources. c-mpl transcripts were found in all megakaryocytic cell lines tested (CMK, CMK-2B, CMK-2D, SO, and DAMI), the CD34+ leukemia cell line KMT-2, and a hepatocellular carcinoma cell line (Hep3B). Among primary tissues, fetal liver cells and brain had detectable levels of c-mpl message, and among primary tumors, none were found to express c-mpl. These data support the conclusion that c-mpl has restricted expression that is primarily, but not exclusively, related to megakaryocytopoiesis. These observations suggest that thrombopoietin is unlikely to have direct effects on other malignant or normal tissue should it have a clinical role in the treatment of chemotherapy-induced thrombocytopenia.

Amino Acid Sequence↗

PubMed1995

Sucrase-isomaltase is an independent prognostic marker for colorectal carcinoma.

PURPOSE: Expression of disaccharidase sucrase-isomaltase (SI) is significantly enhanced during neoplastic transformation of colonic epithelium. Our study was designed to determine whether expression of SI within primary tumors was significantly associated with survival in patients with colorectal carcinoma (CRC). METHODS: SI expression was analyzed by immunohistochemistry in paraffin sections from 182 Stage I to III CRC that had been resected for cure at the New England Deaconess Hospital between 1965 and 1977. Expression was scored as absent or present in 1 to 50 percent or more than 50 percent of tumor cells. Associations were explored among SI expression, other clinical or pathologic variables, and overall survival. The data set is mature, with 91 (56 percent) patients who had died of CRC at a median follow-up of 96 months. RESULTS: Fifty-five percent of primary CRC expressed SI. When the multivariate Cox analysis was performed, nodal status, T stage, primary site, grade, and SI expression were independent covariates. SI expression was not associated with the expression of other clinicopathologic variables but increased the risk of death from colorectal carcinoma by 1.83-fold. DISCUSSION: These results indicate that SI is a prognostic marker for CRC that is independent of stage-related variables in patients who have undergone potentially curative resections.

Aged↗

PubMed1995

Detection of p53 mutations by single-strand conformation polymorphisms (SSCP) gel electrophoresis. A comparative study of radioactive and nonradioactive silver-stained SSCP analysis.

p53 mutations are the most common genetic abnormality in humans tumors, but their clinical significance remains to be precisely elucidated. Conventional single-strand conformation polymorphism (SSCP) analysis, a well-established technique for detecting p53 mutations, uses radioactively labeled polymerase chain reaction (PCR) products, which migrate abnormally in the presence of mutations. We performed radioactive PCR-SSCP analysis in a series of 30 formalin-fixed, paraffin-embedded ovarian carcinomas and two cell lines (SW480 and Caov4) harboring known homozygous p53 mutations and compared the results with nonradioactive silver-stained SSCP. The purpose was to assess whether nonradioactive SSCP is suitable for detecting p53 mutations in a rapid, sensitive, cost-effective fashion, without the need of radioactive isotopes. We accomplished PCR amplification of p53 exons 5 through 8 in 26 carcinomas, and radioactive SSCP detected p53 mutations in 13 tumors; three mutations were localized in exon 5, six in exon 6, two in exon 7, and two in exon 8. All mutations were correctly identified with nonradioactive SSCP, except for one exon 8 mutation. To establish the sensitivity of nonradioactive SSCP, DNA samples of SW480 and Caov4 were mixed with increasing amounts (0-90%) of normal DNA and subjected to PCR-SSCP analysis. Mutations were detected until the concentration of SW480 and Caov4 was 15% and 10%, respectively, of the total sample. The results of our investigation demonstrate that nonradioactive silver-stained SSCP is a sensitive, rapid, and simple technique to detect p53 mutations, even in formalin-fixed tissues, and could be easily used to investigate large series of patients to assess the clinical significance of p53 mutations in human tumors.

Carcinoma↗

PubMed1995

Hepatitis C infection: a rare cause of fulminant hepatic failure.

Fulminant hepatic failure is caused by a variety of viruses, toxins, and metabolic derangements. The hepatitis C virus (HCV) causes indolent development of cirrhosis and has not been associated with fulminant hepatic failure. We report the first documented case of fulminant hepatitis C in the United States. The patient developed jaundice and stage IV encephalopathy. Initial laboratory evaluation did not reveal the etiology. The patient survived without liver transplantation. Three wk later he was found to have a positive HCV RNA and anti-HCV antibody seroconversion. He continued to improve with alpha-interferon treatment and has normal liver function and a negative HCV RNA 15 months later.

Adult↗

PubMed1994

Nodular foci in parathyroid adenomas and hyperplasias: an immunohistochemical analysis of proliferative activity.

Samples of normal, hyperplastic, and neoplastic parathyroid tissues were analyzed for proliferative activity to determine (1) whether a higher number of proliferating cells were detectable in adenoma and hyperplasia versus normal tissues; (2) whether there was a difference in the number of proliferating cells in adenoma versus hyperplasia; and (3) whether there was a relationship between nodularity and proliferative rate in both adenoma and hyperplasia. Formalin-fixed, paraffin-embedded tissue from 21 patients with parathyroid adenoma and 10 patients with hyperplasia (two primary, six secondary, and two tertiary) was analyzed by immunohistochemistry with the monoclonal antibody PC10 to proliferating cell nuclear antigen (PCNA) and, in a subset of cases, with Ki-67 (MIB 1) as markers of cell proliferation. The results were that (1) no proliferating cells were found in normal glands or residual rim of "suppressed" parathyroid tissue; (2) the most intense proliferative activity was confined to nodular areas in both adenomas (57% nodular) and hyperplasias (80% nodular); (3) when fields of highest number of labeled nuclei were chosen, PCNA counts were higher in adenomas than in hyperplasia in both nodular and diffuse areas (P < .05); and (4) the number of nuclei immunoreactive for Ki-67 (MIB-1) was consistently and proportionally lower (range, 13% to 45%; mean, 32%) than the number of those immunoreactive for PCNA, although the nodular pattern was maintained. These findings demonstrate that nodules within parathyroid adenomas and hyperplasias contain subpopulations of cells with a consistently higher proliferative rate than nonnodular areas. Cells within these nodules may be more likely to develop genetic abnormalities that have been observed in hyperplastic and neoplastic parathyroid tissues.

Adenoma↗

PubMed1994

Polymerase chain reaction-based methods for the detection of mutations in oncogenes and tumor suppressor genes.

Altered expression of oncogenes and tumor suppressor genes, the normal function of which is to regulate cell growth and differentiation, represents a central event in the pathogenesis of human cancer. Aberrant expression of these genes is often a result of a mutational event. In vitro amplification of DNA with the polymerase chain reaction (PCR) has enormously increased the sensitivity of the methods to detect mutations. These PCR-based techniques have thus become invaluable in the elucidation of the mechanisms of carcinogenesis as well as in molecular genetics. In addition, the precise definition of a mutation at the molecular level can be a very valuable adjunct to the diagnosis and classification of malignancies as well as to their prognostic assessment. In this article several PCR-based strategies are outlined, their applicability in the detection of different types of mutations is discussed, and finally the application of these techniques in fresh and archival tissues is presented.

Base Sequence↗

PubMed1994

Neural cyst of the ovary with central nervous system microvasculature.

A case of a monodermal teratoma of the ovary composed solely of mature neuroglial elements is described. The cyst lining comprised ependymal cells surrounded by white matter which itself was resting on mesothelial cells. Astrocytes, oligodendrocytes, microglia and neurofilament-positive fibres were seen, but no neuron cell bodies were present. Immunohistochemical stains showed positivity for glial fibrillary acidic protein in ependymal, subependymal and the white matter regions while S-100 protein positivity was restricted to the white matter. Vessels within neuroectodermal tissue, but not those within the mesodermal tissue, stained positively for anti-glucose transporter protein, a marker shown to be present in vessels with barrier functions. We conclude that this is a rare case of monodermal teratoma consisting of purely mature brain tissue with a microvasculature exhibiting blood-brain barrier characteristics.

Adult↗

PubMed1994

The somatostatin receptor SSTR1 is coupled to phosphotyrosine phosphatase activity in CHO-K1 cells.

Somatostatin receptors are abundantly expressed on a variety of human endocrine and epithelial tumors. The ability of these receptors to couple to effector pathways that inhibit the growth of these tumor cells has prompted the use of somatostatin agonists in the treatment of human neoplasms. It has been demonstrated that somatostatin stimulates a phosphotyrosine phosphatase in human tumor cells through a receptor-mediated process. This stimulation may counteract the growth-promoting properties of growth factors and the receptor tyrosine kinases that they activate. The recent cloning and characterization of distinct somatostatin receptor subtypes raise the possibility that different receptor subtypes mediate distinct effector pathways. To determine whether cloned somatostatin receptors could mediate coupling to phosphotyrosine phosphotyrosine phosphatase activity, we examined phosphatase activity after somatotostatin activation of the rat somatostatin receptors SSTR1 and SSTR2 after their stable expression in heterologous Chinese Hamster Ovary (CHO-K1) cells. We found that stimulation of SSTR1 cells was capable of increasing phosphotyrosine phosphatase activity, despite the coupling of both receptors to the inhibition of adenylyl cyclase in these cells. This activation was characterized by an EC50 of 70 nM and was sensitive to pertussis toxin. In addition, we demonstrate that activation of phosphotyrosine phosphatase activity in pituitary cell lines correlates with the endogenous expression of the SSTR1 gene within these cells.

Adenylate Cyclase Toxin↗

PubMed1994

Androgen receptor immunohistochemistry on paraffin-embedded tissue.

Androgen deprivation remains the primary therapy for patients with metastatic prostate cancer. Response to hormonal manipulation, however, has been quite variable. Androgen receptor (AR) expression has been used to predict clinical response to antiandrogenic treatment. However, methods of detection of AR expression have been limited to receptor biochemical assays in cytosolic or nuclear fractions of frozen tissue homogenates with obvious contamination problems by nonmalignant epithelial and stromal cells. As a result, studies correlating AR expression with response to hormonal therapy have been limited and controversial. More recently, immunohistochemical methods of analysis have become available, but only on frozen tissue. We describe a simple method to evaluate ARs on formalin-fixed, paraffin-embedded tissue sections using antigen retrieval methods. Primary, as well as metastatic, prostate carcinomas showed nuclear staining for ARs. Secretory cells stained uniformly in hyperplastic and normal prostatic glands. The majority of stromal cells had strong nuclear positivity. All other cancers tested (colon, breast, lung, skin, kidney) were negative. This immunohistochemical technique allows evaluation of prostate cancer AR status in routinely processed tissues. Thus, application of this technology to archival material should permit assessment of whether AR expression is predictive of response to endocrine therapy in advanced prostate cancer.

Adenocarcinoma↗

PubMed1993

N-myc gene amplification/expression in localized stroma-rich neuroblastoma (ganglioneuroblastoma).

Using nucleic acid analysis and in situ hybridization we have demonstrated N-myc amplification and expression in two children with a localized (stages I and II) stroma-rich neuroblastoma (NB) (ganglioneuroblastoma). The phenomenon was observed in both undifferentiated and mature ganglion-like cells. The two children are alive and disease-free without any treatment after 16 and 17 months. These observations suggest that morphologic differentiation in NB in vivo is not necessarily followed by a decrease in N-myc expression. Moreover, N-myc amplification does not represent an adverse prognostic factor. In contrast with what happens in undifferentiated NB, N-myc amplification does not have an adverse effect on prognosis when occurring in localized (stages I and II), stroma-rich NB with a favorable histology.

Child, Preschool↗

PubMed1993

p53 gene mutations in medulloblastoma. Immunohistochemistry, gel shift analysis, and sequencing.

Medulloblastoma (MB), the most common malignant tumor of the CNS in children, bears a loss of the short arm of chromosome 17 in almost half of the cases. The tumor suppressor gene p53 is located on this chromosome and its role in the pathogenesis of this primitive tumor is controversial. Twenty-two MBs were analyzed by single-strand conformation polymorphism (SSCP) of polymerase chain reaction-amplified conserved exons. Fragments displaying a gel mobility shift were subsequently analyzed by direct sequencing. Immunohistochemistry for p53 was performed in all cases; three had cytogenetic analysis. Two cases (9%) were found to harbor a mutation: one homozygous and one heterozygous. The latter showed focal p53 immunostaining. None of the cases with chromosome 17p abnormality by cytogenetic analysis were found to have a mutation in the remaining allele. Loss of heterozygosity (LOH) of 17p, however, was found in four cases (one by SSCP and three by cytogenetic analysis). Together with the homozygous deletion in one case, the overall incidence of p53 allelic involvement in MB is 23%. Although LOH for the p53 gene may confer a selective advantage to tumor cells harboring mutations with dominant negative oncogenic effect, the infrequent occurrence of p53 mutations in face of frequent LOH for this gene supports the previously formulated hypothesis of a novel tumor-related locus distal to p53 on chromosome 17p.

Adolescent↗

PubMed1992

Quantitative DNA analysis and proliferation in breast carcinomas. A comparison between image analysis and flow cytometry.

The DNA content and proliferation in 100 invasive breast carcinomas were evaluated by computerized image analysis (IA) and flow cytometry (FCM). For DNA content, image analysis of Feulgen-stained slides of fresh tumor imprints were compared with flow cytometry of propidium iodide-stained disaggregated fresh tumor tissue. The DNA indices obtained by the two methods showed close correlation by linear regression analysis (r = 0.89, p less than .001). There were 44 (44%) diploid and 56 (56%) aneuploid tumors. There was agreement between the two methods in detection of aneuploidy in 81% of tumors. Image analysis required smaller tissue samples, permitted direct visualization and selection of tumor cells, and was more sensitive in detecting tetraploid and highly aneuploid cell populations. In contrast, flow cytometry histograms provided better resolution, and were more effective in detecting multiploid tumors and near-diploid aneuploid tumors. Aneuploidy was significantly related to various adverse prognostic parameters, namely, negative estrogen receptor, high mitotic rate, high histologic and nuclear grades. Proliferation was evaluated by measuring the FCM S phase fraction (SPF), and by image analysis quantitation of immunohistochemical staining using Ki-67 monoclonal antibody. SPF and Ki-67 count showed modest correlation (r = 0.42). Both SPF and Ki-67 count were significantly related to the mitotic rate, histologic and nuclear grades. Our results indicate that the two methods provide comparable results, but offer individual advantages and are complementary techniques in analyzing DNA ploidy and proliferation in breast carcinomas.

Adenocarcinoma, Mucinous↗

PubMed1992

p53 gene expression in medulloblastoma by quantitative polymerase chain reaction.

The frequent cytogenetic abnormality--isochromosome 17q [i(17)q]--observed in medulloblastomas (MB) may result in altered expression of the oncosuppressor gene p53 that is located on 17p. p53 expression was therefore evaluated in five MBs and in one MB cell line derived from one of these tumors. Expression levels of p53 utilizing serially diluted unfractionated RNA from tumors and the cell line were assessed both by dot-blot and by reverse transcription (RT) followed by the polymerase chain reaction (PCR). The quality of RNA, efficiency of reaction, and transcript quantitation were determined by simultaneous transcription and amplification of a similarly sized fragment of the alpha-tubulin gene. All MBs showed low levels of expression of p53 compared to those found in normal tissues. p53 messenger RNA (mRNA) was significantly increased (two- to threefold) in the MB cell line compared to its tumor of origin and to the other MBs. Immunoperoxidase studies performed with monoclonal antibodies to the p53 protein product showed focal nuclear expression in one of five of the original tumors while most cells grown in vitro and in the xenograft were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

DNA ploidy, proliferation, and neu-oncogene protein overexpression in breast carcinoma.

DNA content, proliferative activity (Ki-67 immuno-staining and S-phase fraction by flow cytometry), and neu-oncogene overexpression were studied in 135 patients with invasive breast carcinoma. Image analysis and flow cytometry of fresh tumors showed good correlation between the two methods and yielded 39% diploid tumors and 61% aneuploid tumors. Aneuploidy, including tetraploidy, was significantly related to the loss of estrogen (p = 0.0002) and progesterone (p = 0.03) receptors, high histologic (p = 0.014) and nuclear (p less than 0.0001) grades, and mitotic rate (p = 0.0001). Immunohistochemical evaluation of proliferation by staining with Ki-67 monoclonal antibody and of neu-oncogene protein overexpression was performed in fresh frozen tissue from 83 tumors. The Ki-67 score, quantitated by the CAS-200 image analyzer, correlated only moderately with S-phase fraction obtained by flow cytometry by linear regression analysis (r = 0.39, p less than 0.001). However, both of these proliferation markers correlated strongly with the mitotic rate (p less than 0.0001). Aneuploid and tetraploid tumors demonstrated higher Ki-67 scores and S-phase fractions than diploid tumors. Neu-oncogene protein overexpression was seen in 24 tumors (29%) overall and was much higher in aneuploid tumors (38%) and tetraploid tumors (50%) than in diploid tumors (7%). However, the concentration of neu-oncogene protein positive tumors in the tetraploid region reported by others was not observed. Neu-oncogene protein overexpression was also associated with higher Ki-67 scores (p = 0.016) and S-phase fractions (p = 0.037).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1992

Large-cell medulloblastomas. A distinct variant with highly aggressive behavior.

We present four cases of infantile cerebellar neoplasms composed of cells with large vesicular nuclei with prominent nucleoli. All four cases were strongly immunoreactive for synaptophysin, and one case showed immunoreactivity for neurofilaments. Filter hybridization for N-myc and c-myc oncogenes showed a 27-fold c-myc amplification in one case. The cytogenetic analysis in this case showed Double-Minutes and isochromosome 17q. An intracerebral xenograft in nude mice obtained from one such tumor showed a similar morphology to that of the original tumor as well as strong immunoreactivity for synaptophysin and neurofilaments. All the neoplasms were characterized by highly aggressive behavior leading to early cerebrospinal fluid dissemination despite radiotherapy and chemotherapy. We conclude that large-cell medulloblastoma represents a distinct and more aggressive variant of medulloblastoma that requires more aggressive therapy.

Blotting, Southern↗

PubMed1991

Well-differentiated hepatocellular carcinoma associated with long-term survival. Report of two cases.

Two cases of well-differentiated hepatocellular carcinoma (HCC) with focal biliary differentiation are presented. The distinct histological features of these neoplasms and the unusually protracted clinical course of 8 and 10 years distinguish them from previously described pathological categories of primary hepatic tumors. Electron microscopic and immunohistochemical findings support a dual hepatic and bile duct differentiation of the tumor cells. If additional examples of this tumor are found to be associated with a similarly prolonged symptom-free survival, the distinction of this entity from traditional, rapidly fatal HCC becomes important. Less aggressive therapeutic options may be entertained.

Adult↗

PubMed1991

Detection of K-ras mutations in pancreatic and hepatic neoplasms by non-isotopic mismatched polymerase chain reaction.

Mutations within codon 12 leading to activation of Kirsten-ras (K-ras) genes occur in a wide variety of human tumors, but have been reported most frequently in pancreatic carcinomas. We studied twenty-four paraffin-embedded pancreatic and hepatic tumors and two colon carcinoma cell lines with a rapid and simple approach that exploits allele-specific amplification of genomic DNA in a polymerase chain reaction (PCR). We extend the utility of this technique, which is dependent on an exact match at the 3' nucleotide between synthetic oligonucleotides and template DNA, to analyse paraffin-embedded tumor samples for the presence of point mutations at the first and second base of codon 12 of the K-ras gene. The PCR mismatch amplification technique demonstrated a 66% incidence of K-ras mutations at codon 12 in the group of pancreatic neoplasms as a whole. The percentage of mutations varied only slightly in the pancreatic cancer subcategories: 75% in ampullary, 66% in bile duct and 57% in the ductal adenocarcinomas. One islet cell carcinoma and normal tissues adjacent to the tumors revealed wild-type alleles only. One hepatoblastoma and one of six hepatocellular carcinomas also had codon 12 mutations. The PCR mismatch is a sensitive and rapid method that may be useful in screening neoplasms for K-ras point mutation and can be applied to archival material. This application allows a retrospective analyses of a wide range of pathological specimens to determine the role of K-ras mutations in human tumorigenesis.

Amino Acid Sequence↗

PubMed1985

Prognosis and survival as determined by visceral amino acid clearance in severe trauma.

Sepsis, the commonest cause of late death following severe trauma, is related in part to inadequate uptake of amino acids (AA) and synthesis by the liver and other central tissues of proteins essential to immunological defense. Since 'central plasma clearance rate' of amino acids (CPCR-AA) has been found to reflect these functions, serial measurements of CPCR-AA were made in 32 seriously injured patients of whom ten died (31%), nine of sepsis. The mean Index Severity Score on admission for survivors was 31 +/- 1.8 and in deaths 34 +/- 3.9 (N.S.). The blood plasma AA concentrations were not significantly different. However, early in the course before the onset of infection, CPCR-AA in surviving patients was 227 +/- 30 and in those who ultimately died 83 +/- 24 ml/M2/min (p less than 0.001). Later during sepsis the values of CPCR-AA were 176 +/- 28 and 85 +/- 14 ml/M2/min, respectively (p less than 0.01). Thus CPCR-AA appears to be of value as an indicator of amino acid utilization by central tissues and as a predictor of survival or death following severe trauma.

Adult↗