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Biomedical subjects

H G Parsons

Publications and source records attributed to H G Parsons.

At least 19 recordsLinked to original sources
PubMed2004

Stress levels experienced by the parents of enterally fed children.

BACKGROUND: The stress levels of parents of children with chronic illness/disability who were also involved in an enteral feeding programme were examined and compared to the stress levels of parents of healthy children and parents of children with other chronic illnesses reported in previous research. METHODS: Sixty-four parents who had a child with an enteral feeding tube completed the Parenting Stress Index (PSI). RESULTS: Based on criteria developed by Abidin (1995), 42.18% (n = 29) of these parents displayed high stress levels. T-tests revealed that Total Stress scores on the PSI of the parents of children involved in the enteral feeding programme were significantly higher than those reported in the sample of parents used to norm the PSI (P < 0.001), and comparison samples of parents of children with growth deficiencies (P < 0.001) and parents of children with insulin-dependent diabetes mellitus (P < 0.01). Compared to a sample of parents of children with Rett syndrome, the parents of children involved in the enteral feeding programme reported similar levels of stress on the Parent Domain of the PSI and significantly less stress on the Child Domain (P < 0.001). CONCLUSIONS: Factors associated with the stress reported by parents of children with an enteral feeding tube were severity of their child's illness/disability, the constant caretaking demands placed on the parent, and the level of support provided by the parents' social network.

Child↗
PubMed2000

Effect of heterozygosity for the methionine synthase 2756 A-->G mutation on the risk for recurrent cardiovascular events.

Increased dietary intake of folate has been shown to significantly reduce the risk for fatal myocardial infarction, possibly by lowering homocysteine levels. We therefore investigated the association between recurrent cardiovascular events and a mutation in methionine synthase (2756 A-->G)--an enzyme directly involved in folate and homocysteine metabolism. This mutation significantly reduced the risk for recurrent cardiovascular events and elevated red blood cell folate levels.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2000

Inhibition of poly(ADP-ribose) polymerase attenuates inflammation in a model of chronic colitis.

Crohn's disease is a chronic disease characterized by oxidant-induced tissue injury and increased intestinal permeability. A consequence of oxidative damage is the accumulation of DNA strand breaks and activation of poly(ADP-ribose) polymerase (PARP), which subsequently catalyzes ADP-ribosylation of target proteins. In this study, we assessed the role of PARP in the colitis seen in interleukin (IL)-10 gene-deficient mice. IL-10 gene-deficient mice demonstrated significant alterations in colonic cellular energy status in conjunction with increased permeability, proinflammatory cytokine release, and nitrosative stress. After 14 days of treatment with the PARP inhibitor 3-aminobenzamide, IL-10 gene-deficient mice demonstrated normalized colonic permeability; reduced tumor necrosis factor-alpha and interferon-gamma secretion, inducible nitric oxide synthase expression, and nitrotyrosine levels; and significantly attenuated inflammation. Time course studies demonstrated that 3-aminobenzamide rapidly altered cellular metabolic activity and decreased cellular lactate levels. This was associated with normalization of colonic permeability and followed by a downregulation of proinflammatory cytokine release. Our data demonstrate that inhibition of PARP activity results in a marked improvement of colonic inflammatory disease and a normalization of cellular metabolic function and intestinal permeability.

Animals↗
PubMed1999

Hyperhomocyst(e)inemia and the prevalence of atherosclerotic vascular disease in patients with end-stage renal disease.

Hyperhomocyst(e)inemia is now recognized as an independent risk factor for atherosclerotic cardiovascular disease in patients with normal renal function. Hyperhomocyst(e)inemia is common in patients with chronic renal failure. This study is designed to look for an association between hyperhomocyst(e)inemia and atherosclerotic vascular disease in patients with end-stage renal disease (ESRD). Two hundred eighteen patients undergoing hemodialysis were enrolled onto the study and had predialysis bloodwork performed for total homocyst(e)ine, red blood cell folate, and vitamin B(12) levels. A history of clinically significant atherosclerotic vascular disease (ischemic heart disease, cerebrovascular disease, or peripheral vascular disease) was elicited by patient questionnaire and verified by careful inpatient and outpatient chart review. Atherosclerotic vascular disease was present in 45.9% of patients. Mean homocyst(e)ine concentration was 26.7 micromol/L (95% confidence interval [CI], 25.0 to 28.4) overall. Mean homocyst(e)ine concentration was 28.6 micromol/L (95% CI, 25.6 to 31.7) and 25.0 micromol/L (95% CI, 23.2 to 26.8) in patients with and without atherosclerotic disease, respectively (P = 0.036). The adjusted odds ratio for atherosclerotic disease was 2.12 (95% CI, 1.03 to 4.39) for those subjects with a homocyst(e)ine level in the highest quartile compared with the lowest 3 quartiles. In the 126 men, the adjusted odds ratio for atherosclerotic disease was 3.4 (95% CI, 1. 24 to 9.42) for those with homocyst(e)ine levels in the highest quartile compared with the lowest 3 quartiles. No association was found between homocyst(e)ine level and atherosclerotic disease in women. In conclusion, there is an association between hyperhomocyst(e)inemia and atherosclerotic vascular disease in patients undergoing dialysis. Prospective studies need to further examine the relationship between homocyst(e)ine level and atherosclerosis in women with ESRD.

Aged↗
PubMed1999

Hyperhomocysteinemia, anticardiolipin antibody status, and risk for vascular access thrombosis in hemodialysis patients.

BACKGROUND: Vascular access failure is an important cause of morbidity in end-stage renal failure patients on hemodialysis. Currently, little is known about risk factors that predispose certain hemodialysis patients to recurrent access thrombosis. Hyperhomocysteinemia (common in patients with renal failure) predisposes people with normal renal function to recurrent and early-onset venous thrombosis, although the effect on vascular access thrombosis is currently unknown. Previous studies have suggested that high titers of IgG anticardiolipin antibody (IgG-ACA) predispose hemodialysis patients to access thrombosis. This cross sectional study was designed to assess for an association between two predictive variables, hyperhomocysteinemia and elevated titers of IgG-ACA, and vascular access thrombosis in patients undergoing chronic hemodialysis. METHODS: Risk factors for vascular access thrombosis were documented, and the number of episodes of access thrombosis was recorded for the previous three years in patients undergoing hemodialysis. Midweek predialysis total homocysteine and IgG-ACA levels were measured in all subjects. RESULTS: Of the 118 patients who were enrolled, 75.4% had a native arteriovenous fistula. Episodes of vascular access thrombosis were recorded for the previous three years; 34 (28.8%, 95% CI 20.9 to 37.9%) patients had 72 episodes of access thrombosis over the period of risk. Mean homocysteine levels were not significantly different between these 34 patients (28.6 micromol/liter, 95% CI 24.5 to 32.7) and the patients who had no episodes of graft thrombosis (29.8 micromol/liter, 95% CI 26.7 to 32.9). Sixty-seven unselected patients had IgG-ACA levels drawn for analysis, and all assays were negative. The only variable that was associated with a higher risk for graft thrombosis was the type of vascular access placed (odds ratio 4.0, 95% CI 1.6 to 9.6 for patients with a synthetic graft compared with those with an arteriovenous fistula). CONCLUSIONS: No association was found between homocysteine levels or anticardiolipin antibody and vascular access thrombosis in our patient population.

Antibodies, Anticardiolipin↗
PubMed1998

Plasma L-arginine concentration, oxygenation index, and systemic blood pressure in premature infants.

OBJECTIVE: To determine the relationships between plasma L-arginine concentrations and the severity of respiratory distress syndrome (RDS) or systemic blood pressure in premature infants. DESIGN: Prospective, observational study. SETTING: Neonatal intensive care, tertiary referral hospital. SUBJECTS: Fifty-three premature infants. INTERVENTIONS: We measured arginine and nutritional intake, plasma arginine concentration, total amino acid concentrations, and blood pressure on days 3, 7, 14, and 21 of life. In 33 infants who received assisted ventilation, oxygenation index could be calculated to reflect the severity of RDS. The relationships between plasma arginine and oxygenation index or blood pressure were analyzed using multiple linear regression. MEASUREMENTS AND MAIN RESULTS: On day 3, plasma arginine concentrations were decreased compared with normal published values. Arginine concentrations increased with the day of life of measurement (p < .001) and with arginine intake (p < .001). After adjusting for arginine intake and day of life, an inverse relationship was found between oxygenation index and plasma arginine concentrations: (p = .025). No similar relationship was found between oxygenation index and the concentration of total amino acids. A weak positive relationship was found between plasma arginine concentration and systemic blood pressure. CONCLUSIONS: Increments in the oxygenation index, reflective of an increased severity of RDS, are associated with a decrease in plasma arginine concentration. This finding may reflect arginine consumption by the nitric oxide synthase pathway in the lungs of premature infants with RDS, or may be explained by increased arginine catabolism. The lack of a similar relationship between total plasma amino acids and oxygenation index supports the first interpretation.

Amino Acids↗
PubMed1998

Catch-up growth in children treated with home enteral nutrition.

OBJECTIVE: This study was designed to determine the effect of home enteral nutrition on the outcomes of growth and the relationship between growth and entrance anthropometric criteria. METHODS: We reviewed the medical records of 78 consecutive children (median age, 20 months) who were enrolled in the home enteral feeding program at the Alberta Children's Hospital (Calgary, Alberta, Canada) between 1993 and 1995. Weights, heights, and weight-for-heights were expressed as Z scores, using the Centers for Disease Control and Prevention anthropometric growth curve software. To evaluate growth outcome, the total group was further subdivided using anthropometric criteria into appropriate, wasted, or stunted at the time of entry to the program. In a subgroup of 36 children on whom anthropometric data was available for a median length of 5.7 months, Z scores were compared at 3 points in time: before entry, at time of entry, and last follow-up. RESULTS: Patients were classified into five main groups: 11 (14%) had pulmonary disease, 26 (33%) had a gastrointestinal disorder, 21 (27%) had congenital defects, 10 (13%) had a neurologic disorder, and the remaining 10 (13%) had a variety of other illnesses, including malignancies and metabolic disorders. Patients were on the program for a median duration of 8.9 months. It was found that during the period of support within the program, enteral feeding was successful in improving weight-for-age Z scores by 0.42 standard deviations but the effect on height-for-age Z scores and weight-for-height Z scores did not reach significance for this population. The subgroup of 36 children on whom longitudinal anthropometric data was available before entering the program was found to have had a significant drop in weight Z scores between the time before program entry (median length of time, 5.7 months) and the time of program entry, which indicates that these children were falling off the growth curve before commencing enteral feeding. To evaluate growth outcome, the total group was further subdivided using anthropometric criteria into appropriate, wasted, or stunted at the time of entry to the program. In the group of appropriate growth patients, while in the program, 50% had catch-up growth for weight (positive change in Z scores) and 33% for height. In the wasted patients, 92% improved their weight percentile and 75% their height percentile. In the stunted group, 71% had catch-up growth for weight and 74% for height. CONCLUSION: We concluded that the enteral feeding program was able to promote catch-up growth or maintain growth along percentiles in the majority of children.

Adolescent↗
PubMed1998

Improved detection of familial hypercholesterolemia by determining low density lipoprotein receptor expression in mitogen-induced proliferating lymphocytes.

In view of the presence of some 190 mutations in the low density lipoprotein receptor (LDL-R) gene and a lack of simple detection methods, we have developed an improved assay system for detecting familial hypercholesterolemia (FH) using mitogen-induced proliferating lymphocytes. Freshly isolated mononuclear cells were cultured for 3 days in RPMI 1640 supplemented with 10% human lipoprotein-deficient serum (LPDS) and 1% phytohemagglutinin (PHA). LDL-R expression was measured by flow cytometry using a monoclonal anti-LDL-R antibody or DiI-LDL. Mitogenic responses were monitored by cell size (FSC), interleukin-2 receptor (IL2-R) expression, and stimulation index (SI). The LDL-R expression in PHA-stimulated lymphocytes was significantly higher than lymphocytes or monocytes cultured without PHA (15.2- and 3.6-fold, respectively). The gradation of the LDL-R expression was highly correlated to FSC, IL2-R expression, and SI (r > 0.9 in each case). However, no difference in FSC, IL2-R expression, or SI existed between 30 clinically diagnosed FH and 42 normolipemic control subjects. The significantly lower LDL-R expression in the FH group (45.2 +/- 15.3% versus 100 +/- 14.1%; unpaired t test, P < 0.0001) indicated the presence of genetic defects. Normocholesterolemic first degree relatives and non-FH hypercholesterolemic subjects demonstrated normal LDL-R expression as did the controls. The assay carries an efficiency of 97% and both sensitivity and specificity of 98.5%. Measurement of low density lipoprotein receptor expression in phytohemagglutinin- and lipoprotein-deficient serum-stimulated lymphocytes offers a simple method for detecting familial hypercholesterolemia with improved sensitivity.

Adolescent↗
PubMed1997

Lovastatin increases surface low density lipoprotein receptor expression by retarding the receptor internalization rate in proliferating lymphocytes.

We examined the effects of Lovastatin on LDL receptor (LDL-R) expression and rate of internalization in interleukin-2 (IL-2) expanded phytohemagglutinin-stimulated lymphocytes. Lovastatin increased the surface LDL-R expression, but not DiI-LDL uptake, by up to 30% regardless of whether cell proliferation was affected. It caused a dose-dependent reduction in the LDL-R internalization rate as determined with monensin. Lovastatin had no effect on IL-2 receptor internalization. Inhibition of DNA synthesis by hydroxyurea or protein tyrosine kinase activity by genistein failed to affect the LDL-R internalization rate. Co-incubation of cells with Lovastatin and mevalonate or LDL completely restored the rate of LDL-R internalization. We conclude that Lovastatin increases the apparent surface LDL-R expression by retarding the rate of LDL-R internalization. The effect is mediated through the mevalonate pathway but not the anti-mitogenic property of Lovastatin.

Carbocyanines↗
PubMed1997

Surface expression of low density lipoprotein receptor in EBV-transformed lymphocytes: characterization and use for studying familial hypercholesterolemia.

The objectives of the present study were to characterize the surface expression of low density lipoprotein receptor (LDL-R) in Epstein-Barr virus transformed lymphocytes (EBV-L) and to determine the applicability of the cellular system for the study of familial hypercholesterolemia. The EBV-L subsets and LDL-R expression were determined by immuno-cytofluorimetry. The LDL-R expression in EBV-L which consisted of mostly B cells was no different among antigenic subsets. EBV-L cultured in lipoprotein deficient serum demonstrated a 9.3-fold higher LDL-R expression than primary lymphocytes. Lovastatin caused an additional 1.9-and 1.4-fold increase in EBV-L and primary lymphocytes respectively. This difference in lovastatin response is statistically significant (paired t-test, P < 0.001). 54% of the high LDL-R expression in EBV-L was related to the changes in proliferation measured as stimulation index (SI). LDL and lovastatin modulated the LDL-R expression without affecting SI. FH subjects demonstrated 2% (homozygote, n = 1) and 44.6 +/- 12.3% (heterozygotes, n = 35) in LDL-R expression of controls (n = 30). This maintenance of the FH phenotype and the intrinsically high LDL-R expression in EBV-L make the cellular system suitable for the study of FH as well as the regulation of LDL-R.

Adolescent↗
PubMed1997

Plasma L-arginine concentrations in premature infants with necrotizing enterocolitis.

OBJECTIVE: To determine whether L-arginine concentrations (the substrate for nitric oxide synthesis) are lower in premature infants in whom necrotizing enterocolitis (NEC) develops than in unaffected infants. METHODS: We measured arginine and nutritional intake, plasma arginine, glutamine, total amino acids, and ammonia concentrations in 53 premature infants (mean gestational age +/- SD: 27 +/- 1.7 weeks) at risk of NEC. Measurements were done on days 3, 7, 14 and 21 and just before treatment in infants with NEC. RESULTS: Necrotizing enterocolitis developed in 11 infants between postnatal days 1 and 26. On day 3, plasma arginine concentrations were decreased compared with normal published values (mean +/- SE, 41 mumol/L +/- 4). Arginine concentrations increased with day of life of measurement (p < 0.001) and arginine intake (p < 0.001). Plasma arginine concentrations were significantly lower at the time of diagnosis in infants with NEC compared with control subjects, even after adjusting for arginine intake and day of life (p = 0.032). Plasma glutamine and total amino acid concentrations were not significantly different in infants with NEC compared with control subjects. Plasma ammonia concentrations were elevated on day 3 (mean +/- SE, 72 +/- 3.3 mumol/L) and decreased with postnatal age (p < 0.001) and increasing plasma arginine concentrations (p < 0.001). CONCLUSION: Plasma arginine concentrations are decreased at the time of diagnosis in premature infants with NEC. The potential benefit of arginine supplementation in the prevention of the disease deserves evaluation.

Age Factors↗
PubMed1997

Mitochondrial abnormalities of liver in two children with citrullinaemia.

Citrullinaemia is a rare inborn error of urea-cycle metabolism. Two affected children are reported in whom progressive metabolic instability suggested the possibility of hepatopathy or an ongoing hepatic mitochondrial injury. A percutaneous liver biopsy was performed in each patient. Electron-microscopic findings were similar in both cases. Approximately 20% of the mitochondria were abnormally enlarged with paracrystalline inclusions and electron-dense bodies of different sizes and shapes present in the matrix. The specificity of these findings is discussed in the context of previous reports of ultrastructural abnormalities in the hepatocytes of patients with inborn errors of the urea cycle. It is speculated that the mitochondrial abnormalities in citrullinaemia may be related to the accumulation of citrulline in the mitochondria which may eventually manifest as metabolic instability.

Cell Nucleus↗
PubMed1995

Tolbutamide causes a modest increase in insulin secretion in cystic fibrosis patients with impaired glucose tolerance.

We examined the effect of intravenous (i.v.) tolbutamide administration on glucose and hormone levels in cystic fibrosis (CF) patients with impaired first-phase insulin secretion and oral glucose tolerance (oral glucose tolerance test [OGTT]) and compared them with CF patients with only an impaired first-phase insulin secretion and healthy control subjects. Five CF patients with an impaired OGTT, ie, a serum glucose value of 7.8 mmol/L or greater 120 minutes after an oral glucose load (group I), five CF patients with a normal OGTT, ie, a serum glucose not exceeding 7.8 mmol/L 120 minutes after oral glucose (group II), and five healthy control (CON) subjects underwent IV glucose tolerance tests with glucose alone (IVGTT) and glucose administered in conjunction with tolbutamide ([IVTTT] 25 mg/kg; maximum dose, 1 g). Serum glucose levels were measured using the glucose oxidase method; insulin, C-peptide, and glucagon levels were measured by the double-antibody radioimmunoassay (RIA) technique. Serum immunoreactive trypsin (IRT) and hemoglobin A1 (HbA1) levels and height and weight were measured for each subject, and in addition, pulmonary function was assessed in those with CF. There were no significant differences in the area under the curve (AUC) for glucose or glucose or glucagon levels or the serum glucose disappearance rate (k value) between group I, group II, or CON subjects during the IVGTT. First-phase insulin and C-peptide secretion was abnormal during IVGTT and IVTTT in the CF groups: in group I it was severely impaired, whereas in group II it was between group I and CON values. During the IVTTT serum glucose levels and glucose k values were not significantly altered in any of the three groups as compared with the IVGTT.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Modulation in delta 9, delta 6, and delta 5 fatty acid desaturase activity in the human intestinal CaCo-2 cell line.

We report the influence of media lipids, growth in lipid-poor medium, and cell differentiation on delta 9, delta 6, and delta 5 desaturase activity in the human CaCo-2 enterocyte cell line. We also describe the level of incorporation of palmitic (16:0), linoleic (18:2n-6), and eicosapentaenoic (EPA) acids (20:5n-3) and their higher homologues into cytosolic and membrane lipids during long-term (10 days) medium supplementation in fully differentiated 16- to 18-day-old cultures. CaCo-2 monolayers reached confluency by day 6 with subsequent development of microvilli and maximal expression of microvillus membrane sucrose, alkaline phosphatase, and gamma-glutamyltransaminase occurring between days 16 and 23 after plating. There was evidence of the presence and modulation of delta 9, delta 6, and delta 5 desaturase activity (delta 9 > delta 6 > delta 5). delta 6 Desaturase activity decreased approximately 2-fold between days 6 and 24 of culture and when the fetal bovine serum concentration was increased from 0.5% to 25%; in contrast, when cells were starved for 72 h, activity increased 5.4-fold. When the media was supplemented with either linoleic acid and/or EPA, both delta 6 and delta 5 desaturase activities were inhibited, the greatest reduction of delta 5 desaturase activity occurring with EPA. Incorporation of media fatty acids plus their desaturase and elongase products was highly dependent on medium composition with the homologues of delta 9 > delta 6 > delta 5. Supplementation of cellular media with 100 microM EPA for 10 days decreased membrane phosphatidylethanolamine arachidonic acid level from 13.2 to 8.9%. From these results we conclude that enterocyte membrane fatty acid composition and desaturase enzyme activity are regulated by both dietary fat intake and cell maturation. The clinical relevance of these observations on lipid dietary modification for the management of chronic inflammatory bowel disease is still uncertain but these observations suggest that the beneficial effects of EPA supplements on human ulcerative colitis may be due to a reduction in enterocyte arachidonic acid content by down-regulation of delta 6 and delta 5 desaturase activity.

Animals↗