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M Heyman

Publications and source records attributed to M Heyman.

At least 91 records · Page 5Linked to original sources
PubMed1993

Oxidative stress may contribute to the intestinal dysfunction of weanling rats fed a low protein diet.

Intestinal function is impaired in malnutrition. Because oxidative stress is a component of gastrointestinal injury, and malnutrition may reduce antioxidant defenses, we investigated the involvement of oxidative stress in the intestinal dysfunction due to malnutrition. Weanling rats were fed either a normal protein (22% casein) or a low protein (6% casein) diet for 4 wk. In intestinal homogenates, we assessed free radical damage and enzymatic antioxidant defenses. In jejunal fragments mounted in Ussing chambers, we measured ionic transport by short-circuit current (Isc) and protein permeability by transepithelial fluxes of beta-lactoglobulin. Catalase activity and the thiobarbituric acid-reacting substances concentration were greater in intestinal mucosa of the low protein group, whereas the glutathione concentration and the activities of superoxide dismutase and Se-dependent glutathione peroxidase were the same as in the normal protein group intestinal mucosa. Both basal Isc and the delta Isc induced by glucose and forskolin, as well as beta-lactoglobulin fluxes, were higher in the low protein group. Exogenous H2O2 stress increased Isc significantly more in the low protein than the normal protein group but did not alter protein permeability. These results show that malnutrition induces both intestinal free radical damage and altered epithelial transport, suggesting that oxidative stress may contribute to the intestinal dysfunction associated with malnutrition.

Animals↗
PubMed1993

Effect of cytokines on the epithelial function of the human colon carcinoma cell line HT29 cl 19A.

In various intestinal diseases, lymphoid cell infiltration of the lamina propria might be an important factor causing intestinal dysfunction through cytokine release. The effects of such cytokines were therefore measured on chloride secretion and macromolecular transport in intestinal HT29 cl 19A cells. Cells were grown on transwell filters and serosally exposed for two to 48 hours to 1% or 5% concentrations of phytohaemagglutinin (PHA) activated or non-activated healthy human mononuclear cell culture supernatants. These supernatants were tested for their interferon gamma (IFN gamma), tumour necrosis factor alpha (TNF alpha), and interleukin 6 (IL6) concentration. The mean (SE) were 4.72 (1.63), 3.17 (0.14), and 4.47 (1.12) ng/ml in activated supernatants. Intestinal function was studied in Ussing chambers: chloride secretion was assessed from the variations in short circuit current, and epithelial barrier capacity was monitored by the electrical resistance of the HT29 cl 19A cell monolayers and by measuring intact or degraded fluxes of the macromolecular tracer horseradish peroxidase. Release of lactate dehydrogenase (LDH) in the presence of various concentrations of cytokines was assessed as a test for cellular injury. The results indicate that serosal cytokines do not directly stimulate short circuit current. Long term (48 hours) exposure, however, significantly reduced both short circuit current (6.79 (0.65) v 2.90 (1.16) microA/cm2 in control v treated cells) and barrier capacity as shown by the decrease in resistance of the HT29 cl 19A cell monolayers from 158 (10) to 36 (9) ohms.cm2, and the increase in intact fluxes from 167 (33) in controls to 874 (206) ng/h.cm2, in cytokine rich supernatant treated cells and in degraded fluxes from 1113 (114) to 2327 (234) ng/h.cm2. This decreased barrier capacity was associated with an increase in release of LDH F(21.7 (1.2) and 43.6 (2.0) UI/h.cm2 in 1% and 5% cytokine treated monolayers v 10.8 (2.1) UI/h.cm2 in control monolayers). The results indicate that cytokines do not directly stimulate intestinal chloride secretion but that prolonged exposure to these agents reduced both electrolyte transport and barrier capacity to macromolecules through cellular and paracellular pathways.

Cell Membrane Permeability↗
PubMed1993

Have the invisible children become visible?

Over the past 30 years much information has been collected on children whose parents suffer from psychiatric illness. Research has shown that many of these children are at high risk for significant psychopathology but there have been few investigations examining whether or not they are being identified and are receiving mental health care. The purpose of this pilot study was to investigate to what extent the children of psychiatrically ill adult patients are identified and referred to the mental health services. Results of structured interviews with the patients indicate that a considerable number had school-aged children and that in many instances no inquiry had been made concerning the children's psychological health. Although some of the children were reported to have received treatment, few had been referred by their parent's psychiatrists. Recommendations to improve the identification and treatment of such children are outlined in this study.

Adolescent↗
PubMed1993

Chromosome 9 short arm deletions in malignant diseases.

Deletions of 9p21-22, that frequently include the alpha-, beta- and omega-IFN gene cluster, are common in malignant diseases such as acute lymphocytic leukemia, malignant melanoma and malignant glioma. There is also evidence to support the role of a gene(s) on chromosome 9p21 in predisposition for familial malignant melanoma. Although initial studies implicated that the IFN genes could serve as tumor suppressor genes, there is now data, mainly based on estimations of minimum region of overlap for the deletions, indicating that the relevant tumor suppressor gene is located centromeric of the alpha-, beta-, omega-IFN gene cluster.

Chromosome Deletion↗
PubMed1993

Comparative effects of nicotinic acid and nicotinamide on cholera toxin-induced secretion in rabbit ileum.

Nicotinic acid reduces the cholera-toxin induced fluid secretion in experimental animals but its toxicity at high doses prevent its therapeutic use in patients suffering from cholera. This study aimed to determine whether nicotinamide, the non toxic amide derivative of nicotinic acid, is as effective as nicotinic acid in inhibiting cholera toxin induced intestinal secretion in vivo. Four intestinal loops, with their blood supply intact, were isolated in 30 rabbits and injected with either (i) 30 mM mannitol, (ii) 30 mM mannitol + 10 micrograms cholera toxin, (iii) 30 mM glucose, or (iv) 30 mM glucose + 10 micrograms cholera toxin. These rabbits were then randomly assigned to three groups receiving intraluminally either 100 mg/kg of nicotinic acid, 100 mg/kg of nicotinamide, or 10 ml/kg of Ringer solution. Measurement of intestinal fluid accumulation showed that nicotinic acid, but not nicotinamide, significantly reduced cholera toxin induced intestinal secretion.

Animals↗
PubMed1992

Interferon system in primary acute lymphocytic leukemia cells with or without deletions of the alpha-/beta-interferon genes.

Various aspects of the interferon (IFN) system were studied in malignant cells from 37 unselected patients with acute lymphocytic leukemia (ALL). It was found that leukemic cells from two of 37 patients had a complete loss of alpha- and beta-IFN genes, whereas cells from four of 37 had lost one of the alpha-/beta-IFN alleles. In 25 cases, viable cells were also available for functional studies. Cell clones with loss of one of the alpha-/beta-IFN alleles produced low amounts of IFN after virus induction in vitro. Some clones with an apparently normal set of IFN genes were unable to produce detectable amounts of IFN. All clones studied were found to carry high-affinity alpha-IFN receptors. In clones carrying deletions of IFN genes, the cells were sensitive to IFN in vitro as measured by alpha-IFN-induced enhancement of 2',5'-oligoadenylate synthetase (2',5'-A synthetase). Cells from four patients with an apparently normal set of IFN genes were insensitive to this effect of IFN. We conclude that of the 17 patients in which IFN genes, IFN production, alpha-IFN receptors, and IFN-induced enhancement of 2',5'-A synthetase were studied, nine (53%) showed some abnormality in their IFN system. This finding may add some support to the hypothesis that defects in the IFN system could be a step on the path to malignant transformation in ALL. Moreover, patients whose malignant cells carry IFN gene deletions or other defects in their IFN-producing capacity, but are still sensitive to exogenous IFN, could represent a subgroup of ALL with a greater likelihood of responding to IFN therapy.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Effect of cow's milk protein absorption on the anaphylactic and systemic immune responses of young rabbits during bacterial diarrhoea.

In vivo and in vitro studies recently showed that intestinal permeability to cow's milk proteins such as beta-lactoglobulin increased transiently in infant rabbits infected by the enteroadherent Escherichia coli strain RDEC-1 at weaning. The consequences of this enhanced permeability for local anaphylactic and/or systemic immune responses were studied in infected and age-matched control rabbits at weaning, given either water or cow's milk diluted in water in addition to their solid diet. The systemic immune response was determined by measuring IgG, IgA, IgM, and IgE antibodies to cow's milk proteins. A rise in IgG and IgM, but not IgA or IgE, antibody titres to milk protein was observed. Further, infected milk-drinking rabbits had significantly higher beta-lactoglobulin and casein IgG titres than milk-drinking controls. The anaphylactic response was tested by mounting ileal segments in Ussing chambers, adding the milk proteins to the serosal side of the tissue and recording the variation in short-circuit current in order to detect any electrogenic chloride secretion. No change in short-circuit current was observed in the presence of milk proteins in infected or age-matched control milk-drinking rabbits, indicating the absence of any immediate hypersensitivity reaction. These results indicate that at weaning, the rabbit is not prone to developing anaphylactic responses to milk proteins. The rise in milk protein IgG antibodies that followed infection with RDEC-1 might favour the elimination of milk protein-IgG immune complexes from the systemic circulation. The present results emphasize the evidence that genetic background and/or animal species greatly influence the immune response to an antigenic load.

Anaphylaxis↗
PubMed1991

Increased beta-lactoglobulin absorption during rotavirus enteritis in infants: relationship to sugar permeability.

We studied absorption of the potentially allergenic protein beta-lactoglobulin during acute rotavirus diarrhea in infants and assessed the relationship of this macromolecular absorption with intestinal sugar permeability. After oral rehydration, 38 patients with acute gastroenteritis were given orally a 100-ml solution containing 4 g (11.7 mmol/L) of lactulose and 0.8 g (4.4 mmol/L) of mannitol, and their recovery rate as shown in urine passed during the subsequent 5 h was measured. A blood sample was taken 2 h after a milk feed for ELISA measurement of beta-lactoglobulin in circulating immune complexes. Twelve nondiarrhea patients were studied after an overnight fast as controls. Immune complexes containing beta-lactoglobulin were found in the serum of all, but the levels [median (range)] were significantly higher in patients with rotavirus diarrhea [686 (36-4352)] than in nondiarrhea patients [165 (0-2594)]; p = 0.007. The mean (95% confidence interval) lactulose/mannitol urinary recovery ratios were increased in patients with acute diarrhea [0.19 (0.10, 0.30)] compared to nondiarrhea patients [0.01 (0.005, 0.02)]; p = 0.0001. Thus, a significant correlation between beta-lactoglobulin absorption and sugar permeability was found; Spearman's rank correlation coefficient = 0.42, p = 0.004. This correlation was not, however, direct but was due to an inverse relationship between urinary recovery of mannitol and serum beta-lactoglobulin immune complexes. These results indicate that rotavirus gastroenteritis is associated with enhanced beta-lactoglobulin absorption and elevated lactulose/mannitol permeability test results, but these represent different phenomena.

Antigen-Antibody Complex↗
PubMed1990

Quantification of protein transcytosis in the human colon carcinoma cell line CaCo-2.

The transepithelial absorption of food-type proteins has been shown to proceed by endocytosis along two functional pathways: a minor direct pathway allowing transport of intact protein and a major lysosomal degradative pathway. The human colon carcinoma cell line CaCo-2 grown on Millipore filters was used here further to characterize these pathways by measuring HRP transport across the cell monolayer in Ussing chambers. In the apical-basal direction, this transport mainly occurred along the degradative pathway and was inhibited at 4 degrees C (7.41 +/- 1.26 pmoles/h.cm2 vs. 27.40 +/- 8.91 at 37 degrees C). The amount conveyed via the direct pathway was very small (0.89 +/- 0.35 pmoles/h.cm2) and did not diminish at 4 degrees C (1.43 +/- 0.59 pmoles/h.cm2). In the basal-apical direction, HRP transport along the degradative pathway at 37 degrees C was similar to the apical-basal value and was inhibited at 4 degrees C (16.40 +/- 4.05 vs. 2.72 +/- 2.52 pmoles/h.cm2), but along the direct pathway, it was eight times the apical-basal value (8.36 +/- 3.11 pmoles/h.cm2) and was inhibited at 4 degrees C (2.43 +/- 0.78 pmoles/h.cm2). Intact HRP fluxes were not correlated with the electrical resistance of the filters, indicating transport via a transcellular route. Monensin at 10(-5) M did not affect direct or degradative transport in the apical-to-basal direction. These results suggest that in CaCo-2 cells HRP undergoes bidirectional transcytosis by a fluid-phase mechanism, but the extent of degradation during that transport varies according to the membrane (apical or basal) where it is presented.

Biological Transport↗
PubMed1990

Antigen absorption in rabbit bacterial diarrhea (RDEC-1). In vitro modifications in ileum and Peyer's patches.

Intestinal absorption of antigenic (intact) and degraded beta-lactoglobulin and horseradish peroxidase was studied in rabbits experimentally infected at weaning with the rabbit-specific Escherichia coli strain RDEC-1 (015:NM). Transepithelial fluxes of both proteins were measured at four stages after infection: early, peak, late, and recovery, on segments of ileum and Peyer's patches mounted in Ussing chambers. During this period of observation, absorption of antigenic beta-lactoglobulin and intact horseradish peroxidase decreased significantly in the ileum and Peyer's patches of age-matched controls. No significant age-related decrease was observed in the controls for the transport of these proteins in degraded form. RDEC-1 infection caused, first, a rise in degraded protein fluxes across Peyer's patches only, during the early phase of the disease. Second, during the peak phase of infection, absorption of antigenic beta-lactoglobulin by the ileum rose to 74.0 ng/hr/cm2 (90% confidence interval: 63.1, 86.8) vs 15.8 (5.8, 42.8) in the controls (P = 0.07), and absorption of intact horseradish peroxidase rose to 21.8 (16.5, 26.7) ng/hr/cm2 vs 4.4 (0.7, 26.6) in control ileum, (P = 0.09). These rises, which were similar in Peyer's patches, delayed the physiologic decrease in protein absorption that occurs with age. These results indicate that increased antigen absorption is observed during bacterial diarrhea and that it might interfere with the immune responses of the host.

Animals↗
PubMed1990

Effect of oral or parenteral sensitization to cow's milk on mucosal permeability in guinea pigs.

The systemic and local immune responses and the intestinal barrier function were examined in orally or parenterally milk-sensitized guinea pigs. Both types of sensitization led to positive passive cutaneous anaphylactic responses and high IgG titers against beta-lactoglobulin (beta-LG), especially in parenterally immunized animals. In Ussing chambers, sensitized jejunum had higher short-circuit current (Isc) than control jejunum, with and without beta-LG challenge. The further increase in Isc induced by serosal beta-LG treatment was higher in parenterally than orally sensitized animals. Barrier function was tested as the intestinal transport and degradation of horseradish peroxidase (HRP) in the presence and absence of beta-LG. There was a 5-fold increase in degraded HRP transport in sensitized versus control animals, with and without beta-LG challenge. Serosally applied beta-LG enhanced the transport of intact HRP in sensitized but not in control animals. These results indicate that sensitization of guinea pigs to cow's milk permanently increases endocytic and electrogenic activities. The challenge with beta-LG induced a further transient rise in Isc and increased intact HRP transport.

Administration, Oral↗
PubMed1989

Endocytosis and processing of protein by isolated villus and crypt cells of the mouse small intestine.

A small but antigenically significant amount of intact food proteins is absorbed at the intestinal level. These proteins are transported by an endocytotic mechanism mostly in degraded form via the lysosomal pathway of the enterocytes, but those that escape lysosomal degradation appear to be a small fraction of potential food antigens that enter the body. To establish whether protein uptake and processing are similar between mature and immature enterocytes, villus and crypts cells were isolated from the small intestine of adult mice. In each fraction, we measured lysosomal cathepsin activities and cell binding, uptake, and degradation of horseradish peroxidase (HRP). The following results were observed: (a) mice exhibited an increasing villus-to-crypt gradient of cathepsins B and D; (b) binding, internalization and degradation of HRP were twice as high in crypt cells as in villus cells, indicating that the rate of endocytosis in crypt cells doubled; and (c) the percentage of intracellular intact and degraded HRP remained similar in both cell types, suggesting that lysosomal degradation was not the limiting step of endocytosis. Chloroquine and ammonia increased intracellular intact HRP, but monensin did not. These results suggest that intestinal villus and crypt cells do not transfer proteins at the same rate. This may have important biological consequences in physiopathological states in which the crypt/villus ratio is greatly increased.

Animals↗
PubMed1989

Evolution of the caecal epithelial barrier during Clostridium difficile infection in the mouse.

The most striking effect of Clostridium difficile infection is its degrading of the intestinal barrier. The aim of this study is to establish whether the cellular or paracellular constituent of the barrier is the initial target of the toxins produced by C difficile. Accordingly, the caecal epithelium of C3H/He mice was challenged under three experimental conditions with the C difficile strain VPI 10463: (1) by in vivo inoculation of axenic mice, (2) by adding the toxins to ligated caeca in vivo, and (3) by adding them to the mucosal side of isolated caeca in Ussing chambers. Under all three conditions, the epithelial barrier was tested in caeca mounted in these chambers. The transepithelial potential difference (PD), electrical conductance (G), and intact and degraded Horseradish peroxidase (HRP) fluxes were used as indexes of permeability. Results were as follows: (1) In axenic mice, C difficile caused severe infection, produced toxins A and B, reduced PD, and enhanced G and intact HRP fluxes without changing degraded HRP fluxes, (2) four hours after the toxins were added to ligated caeca in vivo, PD was relatively unaltered, but G, and intact and degraded HRP fluxes increased, and (3) when toxins were added to caeca during two hours in the Ussing chambers, the only modification observed was an increase in degraded-HRP fluxes. These results indicate that the C difficile toxins gradually cause intestinal lesions. After an apparent resistance, they stimulate the endocytotic process and then increase paracellular permeability and finally cause loss of cell viability.

Animals↗
PubMed1989

Emergence of Na+-glucose cotransport in an epithelial secretory cell line sensitive to cholera toxin.

Epithelial properties and effects of cholera toxin (CT) and glucose were investigated in human rectal tumor cell line HRT-18. Addition of 10(-3) M dibutyryl adenosine 3',5'-cyclic monophosphate (DbcAMP), 10(-8) M vasoactive intestinal peptide, 10(-5) M epinephrine, and 10(-5) M forskolin to the serosal side and of 3.5 micrograms/ml CT to the mucosal side and of 2 micrograms/ml A23187 to both the serosal and mucosal sides raised short-circuit current (Isc). This rise was reversed by serosal addition of 5 x 10(-5) M bumetanide or 10(-4) M ouabain. In filters treated with CT, Isc and net chloride flux (JClnet) increased after 60 min from 0.05 +/- 0.008 and -0.04 in the Ringer to 0.32 +/- 0.05 and -0.33 mueq.h-1.cm-2, respectively. Addition of 10(-2) M glucose further raised Isc by stimulating net sodium flux (JNanet) (0.70 +/- 0.08 and + 0.58 mueq.h-1.cm-2, respectively). This additional augmentation of Isc was reversed by 0.5 mM phlorizin and was mimicked by 3-O-methyl-D-glucose. When the filters were stimulated by cAMP for 15 min, Isc was also enhanced by addition of glucose. In untreated filters, Isc, JNanet, and JClnet did not differ significantly before and after addition of glucose. It is concluded that HRT-18 cells in basal state do not display absorptive properties but secretory properties stimulated by CT. However they exhibit Na+-glucose cotransport once stimulated by either CT or cAMP.

Adenocarcinoma↗
PubMed1989

Transport of beta-lactoglobulin across rabbit ileum in vitro.

Intestinal transepithelial transport constitutes a major limiting step in the transfer of food protein antigens to the blood. This transport was studied in isolated rabbit ileum in Ussing chamber in vitro for the milk protein antigen beta-lactoglobulin (beta-Lg). The transepithelial passage of beta-Lg was measured by enzyme-linked immunosorbent assay (ELISA) and radiolabeled protein transfer and compared with that of the nonmetabolizable marker polyethylene glycol (PEG)-4000. When 1 mg/ml of beta-[14C]Lg or [3H]PEG was added to the mucosal side of the tissue, the total uptake, measured as the transfer of radiolabeled material across the ileum, was significantly higher for beta-Lg than for PEG (5.46 +/- 1.75 vs. 1.43 +/- 0.26 micrograms.h-1.cm-2). Measured by ELISA, 6-9% of the total amount of beta-Lg transported was absorbed in an intact antigenic form. This transport of intact beta-Lg was inhibited by the metabolic inhibitors 50 mM 2-deoxyglucose and 1 mM azide added simultaneously, was reduced by the microtubule assembly inhibitor 0.05 mM colchicine, and was enhanced by 20 mM ammonia, which inhibits lysosomal proteolytic activity. These results indicate that beta-Lg is efficiently absorbed by the intestinal mucosa of adult animals, partly in intact antigenic form and that beta-Lg transport is probably transcellular, as observed for other proteins. The finding that beta-Lg is absorbed in intact antigenic form agrees with other reports implying that beta-Lg is the main factor responsible for milk protein immunoreactivity and intolerance.

Ammonia↗
PubMed1989

Antigen absorption in bacterial diarrhea: in vivo intestinal transport of beta-lactoglobulin in rabbits infected with the entero-adherent Escherichia coli strain RDEC-1.

We studied the absorption of both antigenic and degraded beta-lactoglobulin (beta-LG) from the ileum to the portal blood, in rabbits infected at weaning with the entero-adherent Escherichia coli strain RDEC-1. The infection was characterized by high bacterial excretion from days 7 to 18 postinfection (pi), acute diarrhea for 10 days, and considerable growth retardation. Intestinal absorption of beta-LG was measured at four stages of the infection: early (day 3 pi), peak (day 10 pi), late (day 18 pi), and recovery (day 30 pi). During the 30-day period of infection, age-matched control rabbits exhibited a significant decrease in antigenic and degraded beta-LG absorption. In both control and infected animals, more than 90% of the beta-LG was absorbed by a degrading pathway and the remainder in antigenic form by a minor pathway. RDEC-1 infection significantly raised antigenic beta-LG absorption from days 10 to 30 pi, which delayed the decrease that normally occurs with age. Degraded beta-LG absorption was not modified by the infection, except for a slight increase observed at the recovery stage (day 30 pi). These results suggest that RDEC-1 diarrhea increases absorption of food antigens. The subsequent local or systemic immune responses are not known, but pathologic consequences are possible in susceptible individuals.

Animals↗