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Biomedical subjects

M Heyman

Publications and source records attributed to M Heyman.

At least 73 records · Page 4Linked to original sources
PubMed1996

Prognostic importance of p15INK4B and p16INK4 gene inactivation in childhood acute lymphocytic leukemia.

PURPOSE: The present study explores the prognostic importance of p16INK4/p15INK4B gene inactivation in childhood acute lymphocytic leukemia (ALL). MATERIALS AND METHODS: Cells from 79 pediatric ALL patients were investigated for inactivation of the p15INK4B and p16INK4 genes or loss of heterozygosity (LOH) for chromosome 9p markers by use of Southern hybridization, restriction fragment length polymorphism (RFLP) analysis, microsatellite analysis as well as single-strand conformation polymorphism (SSCP) analysis, and nucleotide sequencing of the p15INK4B and p16INK4 genes. Genetic data were correlated to clinical outcome and established prognostic factors. RESULTS: Inactivation of the p15INK4B and/or p16INK4 genes by homozygous deletion or loss of one allele and mutation of the other was detected in 24 cases (30%). Another 12 patients (15%) showed loss of one allele. A statistically significant correlation was found between inactivation of the p15INK4B/p16INK4 genes and poor prognosis (P < .01). Furthermore, inactivation proved to be an independent factor that predicted relapse, ranking second to WBC count. The trend toward overrepresentation of treatment failure was strongest in the high-risk (HR) group patients with p16INK4/p15INK4B gene inactivation. Patients with deletion of genetic material on 9p21 and normal coding sequence of the remaining p16INK4 and p15INK4B genes had a similar prognosis to that of nondeleted cases. CONCLUSION: The data suggest that analysis of p15INK4B/p16INK4 genes may contribute prognostic information in pediatric ALL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Inactivation of the p15INK4B and p16INK4 genes in hematologic malignancies.

The recently discovered p15INK4B and p16INK4 genes encoding cell cycle regulating proteins, map to a region on chromosome 9p21 that is commonly deleted in a variety of malignant diseases. The p16INK4 gene has now been shown to be a tumor suppressor gene. It is frequently inactivated in cancer and is possibly the second most often mutated gene in human malignant disease after p53. The role of the p15INK4B and p16INK4 genes in hematologic malignancies has been the subject of intense investigation since their discovery. In this review we address the function and possible role in tumorigenesis of the p15INK4B and p16INK4 genes and discuss their significance as prognostic markers in hematologic malignancies.

Carrier Proteins↗
PubMed1995

13q deletions in lymphoid malignancies.

Previous studies have indicated that a candidate tumor suppressor gene resides telomeric of the RB1 gene at 13q14, a region that is commonly deleted in B-cell chronic lymphocytic leukemia (B-CLL). In this study, we have evaluated the frequency and minimal region of overlap for 13q deletions in malignant cells from various lymphoid neoplasms. We observed losses at 13q14 in 33/75 (44%) B-CLL cases, four of 16 (25%) non-Hodgkin's lymphoma (NHL) cases, eight of 29 (28%) patients with acute lymphocytic leukemia (ALL), and one of 15 T-cell lines. In some ALL cases, inactivation of the RB1 gene is suggested as the important event in the 13q deletions. The most commonly deleted marker in CLL and NHL was D13S319, between RBkpt and the D13S25 loci. Homozygous deletions of this marker were observed in 10 of 75 B-CLL cases, in six of which the homozygous deletions included only the D13S319 locus. Our data suggest that 13q deletions are common in lymphoid neoplasms, and that deletion of a candidate tumor suppressor gene(s) in the vicinity of the D13S319 marker is a tumorigenic event in these diseases.

Base Sequence↗
PubMed1995

p15ink4B and p16ink4 gene inactivation in acute lymphocytic leukemia.

Malignant cells from 52 children with acute lymphocytic leukemia (ALL) were investigated for inactivation of the p15ink4B and p16ink4 genes and other genetic alterations on chromosome 9p21. Homozygous deletions of the p15ink4B and/or the p16ink4 genes were detected in 16 cases and a further 9 cases showed evidence of allelic loss either by hemizygous deletion or loss of heterozygosity (LOH) for 9p21 markers. Most cases had loss of both genes, but 5 patients had lost only p16ink4 and 2 cases had homozygous loss of p15ink4B only. Sequence analysis of all exons of p15ink4B and p16ink4 was performed in patients with hemizygous deletions or LOH for 9p21 markers. A frame shift mutation of p16ink4 exon 1 was shown in 1 case, whereas all other clones carried the wild-type sequence of p15ink4B and p16ink4 in the remaining allele. The data suggest that both the p15ink4B and p16ink4 genes can be inactivated in ALL. The existence of a hitherto undefined tumor-suppressor gene on chromosome 9p cannot be ruled out.

Base Sequence↗
PubMed1995

Lymphocytosis of large granular lymphocytes in patients with Hodgkin's disease.

Clonal disorders of large granular lymphocytes (LGL) of either CD3- (NK cell) or CD 3+ (T-cell) phenotype have been described. B-cell malignancies such as hairy cell leukemia and non-Hodgkin's lymphoma have been observed in association with the T-cell type of LGL leukemia. Here we report the occurrence of LGL lymphocytosis in four patients with Hodgkin's disease. Immunophenotyping studies showed that these LGL were CD 3- in three patients and CD3+ in the other. LGL were polyclonally expanded in both patients in whom clonality could be assessed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Tumour necrosis factor-alpha induces morphological and functional alterations of intestinal HT29 cl.19A cell monolayers.

TNF-alpha is a widely distributed proinflammatory cytokine, involved in many disease states. Although it has widely distributed effects, a precise mechanism of action has never been described, in particular at the epithelial level. Morpho-functional changes of the intestinal epithelial monolayer HT29 cl.19A exposed to TNF-alpha were therefore assessed, using electron microscopy (including freeze-fracture replica analysis), as well as measurement of mannitol, Na+ and horseradish peroxidase fluxes across intestinal HT29 cl.19A cell monolayers using Ussing chambers. TNF-alpha receptors were induced on HT29 cl.19A cells by a small non-toxic dose of IFN-gamma (5 U/ml). After 4 h of the combined presence of TNF-alpha (10 ng/ml) and IFN-gamma (5 U/ml), the tight junction structure was altered as shown by a significant decrease in the average strand number measured in the apico-basal direction (5.50 +/- 2.70 vs 3.73 +/- 1.39 in control and treated cells respectively, P < 0.0001) and by a significant decrease in junctional depth (0.27 +/- 0.14 and 0.17 +/- 0.10 microns in control and treated cells respectively, P < 0.0001). These results are in agreement with a decrease in number of 'kiss' sites between contiguous membranes of TNF-alpha treated cells observed in ultrathin sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Membrane Permeability↗
PubMed1995

Intestinal transport and processing of immunoglobulin G in the neonatal and adult rat.

The proximal intestine of neonatal rats expresses a specific receptor (RFcn) that binds immunoglobulin G (IgG) and is no longer expressed after weaning. The aim of this study was to quantify and compare the intestinal transport and processing of IgG in intestinal fragments with or without RFcn, with the fluid-phase transport of horseradish peroxidase (HRP). The mucosal to serosal transport and degradation of IgG and HRP were measured in neonatal and adult rats in vitro in Ussing chambers. IgG transcytosis occurred without degradation in the proximal intestine of neonatal rats, where RFcn is expressed, up to a luminal concentration of 300 micrograms/ml. At higher mucosal IgG concentrations, a degradative pathway was also involved. The immunoreactive IgG fluxes across the proximal intestine of neonatal rats were higher than those observed in the distal neonatal intestine or those in the proximal and distal adult intestine. The rate of HRP transcytosis was higher than that of IgG but it involved a mainly degradative pathway. These results suggest that in the proximal intestine of the neonatal rat, where RFcn is expressed, the transcytotic rate for IgG is not increased, but the nondegradative transport of immunoreactive IgG is favored, especially at low luminal concentrations.

Aging↗
PubMed1995

Jejunal response to beta-lactoglobulin in infants with cow's milk allergy.

Weaning is a transient period of life during which maternal proteins are replaced by foreign proteins. Concomitantly, in early postnatal life, both digestive and immune systems undergo a maturation process. Allergy to cow's milk protein may develop in human infants during weaning, determining digestive, respiratory, cutaneous or systemic symptoms. We studied the intestinal response to bovine milk beta-lactoglobulin (beta-LG) in infants with cow's milk allergy, first during the active phase, and then during the symptom-free stage. During the active phase, transepithelial transport of the beta-LG across the intestinal epithelial layer stimulated the sensitized subepithelial immune cells. This stimulation induced a rise in short-circuit current suggestive of an electrogenic chloride secretion and impaired protein handling by the epithelium. These findings underline the dual role of the epithelial layer in intestinal function: on one hand, it takes an active part in allowing dietary antigens to stimulate the submucosal system, and on the other hand becomes the target for mediators involved in food allergy.

Biopsy↗
PubMed1994

Molecular analysis of the retinoblastoma gene in primary ovarian cancer cells.

Loss of heterozygosity (LOH) at the site of the retinoblastoma (RB1) gene, at 13q14, has been shown to occur in a high proportion of ovarian cancer patients. Based on this, RB1 gene inactivation was studied in primary tumor cells from 15 patients with ovarian cancer. Structural changes as well as expression of the RB1 gene were investigated. One patient had a nondisjunctional deletion at the RB1 locus, and the duplicated remaining allele carried a deletion of exon 21. In another patient, without detectable structural changes of the RB1 gene, no RB protein was detected. Allelic losses at the RB1 locus were observed in 8/13 informative cases (61%). Our results indicate that inactivation of the RB1 gene plays a role in tumor development in a minority of ovarian cancer patients. Another gene(s) on 13q also seem(s) to influence malignant transformation in patients with ovarian cancer.

Chromosomes, Human, Pair 13↗
PubMed1994

Multiple genetic events involving RB1 gene deletion and amplification of chromosome 21 in a case of acute lymphocytic leukemia.

A patient with acute lymphocytic leukemia was found to have a hyperdiploid karyotype, characterized by hexasomy 21 and del(7)(p15). It was shown that the four extra copies of chromosome 21 were all derived from only one of the homologous chromosomes. Molecular analysis showed that the patient had a deletion of both alleles of the retinoblastoma (RBI) gene. These results suggest that multiple events, including loss of RBI gene function and amplification of a key gene(s) on chromosome 21, have contributed to the leukemic transformation.

Alleles↗
PubMed1994

Mononuclear cells from infants allergic to cow's milk secrete tumor necrosis factor alpha, altering intestinal function.

BACKGROUND/AIMS: Intestinal dysfunction observed during cow's milk allergy (CMA) is incompletely understood, and neither the effector cells nor the mediators responsible have been clearly identified. This study was undertaken to better characterize the implication of mononuclear cells in food allergy. METHODS: Peripheral blood mononuclear cells (PBMC) from infants with CMA were cultured in the presence of cow's milk proteins (CMP), and the release of tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), and interleukin 4 and 6 was measured. The effect of culture supernatants was tested on HT29 cl.19A intestinal cell monolayers mounted in Ussing chambers. RESULTS: When stimulated by CMP, PBMC from infants with CMA released more TNF-alpha than those from control infants (429 +/- 92 vs. 205 +/- 34 pg/mL). Culture supernatants did not directly stimulate electrogenic chloride secretion by HT29 cl.19A cells, but epithelial barrier capacity was altered as shown by the significant decrease in electrical resistance (85 +/- 17 vs. 135 +/- 14 omega.cm2 in controls) and the increases in intact horseradish peroxidase, [14C]mannitol, and 22Na+ fluxes. These effects were reversed when culture supernatants were neutralized with anti-TNF-alpha antibodies. Recombinant human-TNF-alpha altered the HT29 cl.19A epithelial barrier capacity, and its effect was highly potentiated by IFN-gamma. CONCLUSIONS: These results indicate that during CMA, the high level of TNF-alpha released by mononuclear cells after milk protein challenge acts synergistically with IFN-gamma to increase the intestinal permeability.

Cell Line↗
PubMed1994

Milk proteins, cytokines and intestinal epithelial functions in children.

This paper discusses the relationship between food antigens, lymphocytes and the epithelial properties of the jejunum in children with cow's milk allergy. Experimental results indicate that increased protein permeability is not the primary cause of cow's milk allergy. Rather, results are interpreted as a secondary effect of an abnormal immunological response leading to mucosal inflammation and impairment of the endocytic process by the intestinal epithelial cells. Stimulation by cow's milk proteins caused the lymphocytes from infants with cow's milk allergy to release more tumor necrosis factor-alpha TNF alpha than those from control infants. After appropriate antigenic stimulation, the cytokines released by the activated lymphocytes from these infants perturbed epithelial function, in particular its barrier capacity. Tumor necrosis factor alpha, together with gamma interferon are involved in these adverse effects. It is thought that bovine beta-lactoglobulin present in the intestinal lumen may be responsible for the secretory diarrhea observed in children with cow's milk allergy, as a consequence of stimulation of electrogenic chloride secretion. In addition, luminal foreign protein may stimulate the submucosal cells. As a consequence, the submucosal release of mediators, including lymphokines, might alter the intestinal epithelial barrier. In conclusion, in physiological conditions, the subepithelial tissue that comprises the immune system and many other systemic systems receive information on the antigenic content within the intestinal lumen via the intestinal epithelium.

Child↗
PubMed1994

Relation between chloride secretion and intracellular cyclic adenosine monophosphate in a cloned human intestinal cell line HT-29 cl 19A.

The relation between the intracellular cyclic adenosine monophosphate (cAMP) content and the electrogenic chloride secretion induced by cholera toxin was studied in secretory HT-29 cl 19A cell monolayers. Cells were treated by the mucosal addition of cholera toxin (5 micrograms/ml) for 10, 45, or 90 minutes in Ussing chambers. After 10 minutes, the mean (SEM) intracellular cAMP content (3.2 (0.2) pmol/mg protein) and short circuit current (Isc) (1.9 (0.3) microA.cm-2) did not differ significantly from the corresponding basal values. At 45 minutes, a significant increase in the Isc (22.2 (5.7) microA.cm-2) was accompanied by a significant elevation in cAMP (10(1.7) pmol/mgh protein). At 90 minutes, when the stimulated Isc plateaued (35.2 (5.2) microA.cm-2), the cAMP value (99.2 (23.8) pmol/mg protein) increased further. The protein kinase C (PKC) activity of the cells was not affected by cholera toxin. Treatment of cell monolayers by different concentrations of DbcAMP (10(5), 5 x 10(-5), 10(-3) M) showed that the minimal concentration of DbcAMP (serosal) which significantly increased the Isc (delta 4.5 microA.cm-2) was 10(-4) M, and that this was accompanied by an increase in cAMP of delta 6.7 pmol/mg protein: Compared with DbcAMP, cholera toxin stimulated the Isc (at 45 minutes) to a much higher degree with a comparable elevation of cAMP. It is concluded that in cl 19A cells there is a threshold value of increase in intracellular cAMP that induces chloride secretion. Cholera toxin stimulated chloride secretion can be explained predominantly by an increase in intracellular cAMP that is unrelated to PKC activity.

Bucladesine↗
PubMed1994

Apical-to-basolateral transepithelial transport of human lactoferrin in the intestinal cell line HT-29cl.19A.

The role of human lactoferrin (hLf) in alimentary iron absorption across intestinal cells was explored using a human differentiated colon carcinoma cell line, HT-29cl.19A. The apical surface of HT-29cl.19A cell monolayers exhibited 1.5 x 10(6) specific binding sites for hLf per cell, with a dissociation constant of 8.3 x 10(-7) M. The apical-to-basolateral transport of 125I-labeled hLf (125I-hLf) or 125I-59Fe-labeled hLf (125I-[59Fe]hLf) was investigated using filter-grown HT-29cl.19A cell monolayers mounted in Ussing chambers. Transport of total (intact plus degraded) hLf, measured by the 125I flux, was not saturable up to an apical hLf concentration of 12.5 microM, whereas immunoreactive hLf transport measured by enzyme-linked immunoabsorbent assay was saturable at 3.75 microM. Lowering the temperature to 4 degrees C reduced the total and immunoreactive hLf fluxes by 77% and 90%, and colchicine (500 microM) reduced these fluxes by 30% and > 97%, respectively. These results indicate that both types of transport are transcellular. Electrophoretic analysis revealed that 125I-hLf transported to the basal compartment consisted of largely degraded fragments (< 2 and 10-20 kDa) and a small portion of intact hLf. At an apical concentration of 3.75 microM diferric 125I-[59Fe]hLf, the immunoreactive hLf flux (64.6 +/- 14.3 ng.h-1.cm-2) constituted approximately 12% of the total hLf flux (552.0 +/- 61.6 ng.h-1.cm-2) and was similar to the [59Fe]hLf-equivalent flux (77.0 +/- 12.3 ng.h-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1994

Interferon system defects in malignant T-cells.

Deletions of chromosome 9p21-22 occur in acute lymphocytic leukemia (ALL), melanoma and glioma. With some exceptions, these deletions include the alpha- and beta-interferon (IFN) genes. In this study, the frequency of alpha- and beta-IFN gene deletions was investigated in 17 T-cell lines, and losses of IFN genes were related to other aspects of the IFN system. Deletions of alpha-/beta-IFN genes were observed in 7/17 cell lines. In two cases the deletions were homozygous for both loci. In most cases aberrations of chromosome 9 were also apparent on cytogenetic analysis. An increased proportion (40% as compared to the expected 13%) of the remaining ten cell lines showed homozygosity for all five common polymorphic alpha-/beta-IFN markers, possibly implicating allelic deletion by loss of heterozygosity (LOH) in some of these clones. The cell lines showed a large variability in IFN production, IFN-alpha receptor number, susceptibility to IFN measured as induction of the enzyme 2',5' oligoadenylate synthetase and cell growth inhibition. No correlations between loss of IFN genes and IFN-producing capacity, or susceptibility to IFN, were found. Of the seven cell lines with a normal IFN-gene dosage and heterozygosity for the alpha- and beta-IFN genes, three had a deficiency in their IFN-producing capacity and one was also insensitive to growth inhibition by IFN. All IFN-producing cell lines predominantly produced beta-IFN.

2',5'-Oligoadenylate Synthetase↗
PubMed1993

Deletions of the short arm of chromosome 9, including the interferon-alpha/-beta genes, in acute lymphocytic leukemia. Studies on loss of heterozygosity, parental origin of deleted genes and prognosis.

A restriction fragment length polymorphism (RFLP) analysis of the alpha- and beta-interferon (IFN) genes was performed in malignant cells from 52 patients with acute lymphocytic leukemia (ALL). Normal cell DNA was available for comparison in 23 of the patients. Ten patients were found to have gross alterations of their alpha- and beta-IFN genes. Leukemic cells from 2 ALL patients showed a complete loss of alpha- and beta-IFN genes. Seven patients had a hemizygous loss of one of the alpha- and beta-IFN alleles, as shown by RFLP analysis and/or loss of signal intensity. In one other patient the malignant clone was reduced to homozygosity with regard to the alpha- and beta-IFN genes, without loss of signal intensity. In patients without hemizygous deletions, the overall incidence of complete homozygosity for the alpha- and beta polymorphisms was higher than expected. Analysis of the data indicates that the total frequency of ALL clones with gross alterations of the IFN-loci is around 30%. A 9p24 probe detected hemizygous deletions in 2 cases of IFN gene deletions. In the other tested cases the deletions were interstitial. No deletions of 9p24 were detected in patients without allelic losses of IFN genes. In 5 cases of allelic IFN gene deletions, DNA from parents was available for comparison. In 4 cases the deleted allele was derived from the mother, whereas in the fifth it originated from the father. Pediatric ALL patients with IFN-gene deletions or homozygosity for all polymorphisms in the IFN-loci had a significantly worse prognosis than heterozygotes. We conclude that deletion of alpha- and beta-IFN genes is a relatively common event in ALL and that RFLP analysis of the IFN genes may provide additional prognostic information in childhood ALL. Whether or not the IFNs act as tumor-suppressor genes in this disease is not yet known.

Adolescent↗