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Biomedical subjects

N Colman

Publications and source records attributed to N Colman.

At least 19 recordsLinked to original sources
PubMed1995

L206W mutation of the cystic fibrosis gene, relatively frequent in French Canadians, is associated with atypical presentations of cystic fibrosis.

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Over 400 mutations have been reported at this locus. Although severe forms of cystic fibrosis are usually associated with pancreatic insufficiency, pulmonary dysfunction, and elevated sweat chloride, there is a wide range of phenotypes, including congenital absence of the vas deferens, observed with some of the milder mutations. The L206W mutation, which was first identified in patients from South France, is relatively frequent in French Canadians from Quebec. In this report, we document the atypical form of cystic fibrosis associated with this mutation, in a cohort of 7 French Canadian probands.

Adult↗
PubMed1993

Passive immunotherapy in the treatment of advanced human immunodeficiency virus infection.

To evaluate the safety and efficacy of passive immunotherapy for advanced human immunodeficiency virus (HIV) infection, a randomized, double-blind, controlled trial of human anti-HIV hyperimmune plasma was conducted. Sixty-three subjects with stage IV HIV disease (AIDS) were randomized to received 250 mL of either HIV-immune plasma or HIV antibody-negative plasma every 4 weeks. Although nonsignificant trends toward improved survival and delayed occurrence of a new opportunistic infection were noted, no significant effects on absolute CD4 lymphocyte counts or quantitative HIV viremia were seen. The only notable toxicity was the allergenicity to be expected from infusing plasma products, usually manifesting as urticaria. Thus, results do not rule out the potential usefulness of passive immunization with different preparations, but did fail to demonstrate clinical benefit of the product studied.

Adult↗
PubMed1993

Computed tomography in the early detection of asbestosis.

Computed tomography (CT; both conventional (CCT) and high resolution (HRCT)) scans of the thorax were evaluated to detect early asbestosis in 61 subjects exposed to asbestos dust in Québec for an average of 22(3) years and in five controls. The study was limited to consecutive cases with chest radiographs of the International Labour Organisation categories 0 or 1 determined independently. All subjects had a standard high kilovoltage posteroanterior and lateral chest radiograph, a set of 10-15 1 cm collimation CCT scans and a set of three to five 2 mm collimation HRCT scans in the upper, middle, and lower lung fields. Five experienced readers independently read each chest radiograph and sets of CT scans. On the basis of three to five readers agreeing for small opacities of the lung parenchyma, 12/46 (26%) negative chest radiographs were positive on CT scans, but 6/18 (33%) positive chest radiographs were negative on CT scan. On the basis of four to five readers agreeing on a chest radiograph, 36/66 (54%) subjects were normal (group A), 17/66 (26%) were indeterminate (group B), and 13/66 (20%) were abnormal (group C). By the combined readings of CCT and HRCT, 4/31 (13%) asbestos exposed subjects of group A were abnormal (p < 0.001), 6/17 (35%) of group B were abnormal, and in group C, 1/13 (8%) was normal, 2/13 were indeterminate, and 10/13 (77%) were abnormal. Separate readings of CCT and HRCT on distinct films in 14 subjects showed that all cases of asbestosis were abnormal on both CCT and HRCT. Inter-reader analyses by kappa statistics showed significantly better agreement for the readings of CT than the chest radiographs (p < 0.001), and for the reading of CCT than HRCT (p < 0.01). Thus CT scans of the thorax identifies significantly more irregular opacities consistent with the diagnosis of asbestosis than the chest radiograph (20 cases on CT scans v 13 on chest radiographs when four to five readers agreed, 13% of asbestos exposed subjects with normal chest radiographs or 21% of asbestos exposed subjects with normal or near normal chest radiographs. It decreased the number of indeterminate cases significantly from 17 on chest radiographs to 13 on CT scans. All cases of asbestosis detected only on CT scans were similarly seen on CCT and HRCT and did not have significant changes in lung function. The CT scans significantly reduced the inter-reader variability, despite the absence of ILO type reference films for these scans.

Adult↗
PubMed1993

Performance of Gem Premier blood gas/electrolyte analyzer evaluated.

We evaluated a new analyzer designed for point-of-care testing of blood gases, sodium, potassium, ionized calcium, and hematocrit. The Gem Premier (Mallinckrodt) system has two components: the analyzer and a disposable cartridge. Analysis takes place in the cartridge, which contains the electrochemical sensors, the calibrants, the reagents, the sampling stylus, and the waste container. The system was evaluated for imprecision and accuracy. With aqueous control materials, total imprecision (CV) was: pH, 0.10-0.18%; PCO2, 3.16-5.78%; PO2, 2.92-4.85%; sodium, 0.82-1.44%; potassium, 1.35-1.48%; ionized calcium, 0.75-1.45%; and hematocrit, 1.13-1.83%. Accuracy of the system was assessed by split-sample comparison with the Radiometer ABL 330 blood gas analyzer for pH and blood gases, the Nova Stat Profile 5 for whole-blood electrolyte and hematocrit analysis, and the IL Phoenix for plasma electrolyte analysis. After outlier correction, regression statistics were excellent for all analytes except sodium, which demonstrated Sy[x values between 1.80 and 2.30 mmol/L and 0.85 < or = r < 0.90.

Blood Gas Analysis↗
PubMed1993

Analytical evaluation of i-STAT Portable Clinical Analyzer and use by nonlaboratory health-care professionals.

We evaluated the performance of the i-STAT Portable Clinical Analyzer, a hand-held instrument that, with its current cartridge, analyzes for electrolytes, urea nitrogen, glucose, and hematocrit in approximately 60 microL of whole blood in approximately 90 s. Accuracy, imprecision, and linearity studies were performed with aqueous controls and standards and by split-sample analysis. Intrarun imprecision (CV) ranged from 0.34% to 3.97%. Total imprecision over a 2-month period ranged from 0.42% to 4.83%, with urea nitrogen and glucose analyses generating the higher values. Patients' results from the Portable Clinical Analyzer correlated well with those obtained for whole blood or plasma by the Nova Stat Profile 5, the Beckman Synchron CX3, or the Technicon H1 Hematology Analyzer, with Sylx values < 0.2 mmol/L for potassium; < 1.5 mmol/L for sodium, glucose, and urea nitrogen; < 2.4 mmol/L for chloride, and < 2.4% for hematocrit. We also ascertained imprecision and accuracy of the system placed in a cardiothoracic intensive-care unit and operated by nurses. There were no significant differences in either the imprecision or accuracy of the system in this setting. We conclude that operator technique is not a factor in the analytical performance of the system and that it can be used by nonlaboratorians with a high degree of confidence that reliable results will be obtained.

Autoanalysis↗
PubMed1992

Maternal vitamin levels during pregnancies producing infants with neural tube defects.

Women at very high risk for having a child with a neural tube defect (NTD) because they had previously delivered affected children significantly reduced their recurrence rate by taking folate supplements before conception. To clarify how these results might apply to a lower-risk general obstetric population, we measured folate, vitamin B12, and retinol levels in maternal serum drawn early in 89 pregnancies resulting in NTD offspring and 178 control pregnancies identified from the Finnish Registry of Congenital Malformations. In 86.5% of the subjects, specimens were collected within 8 weeks after neural tube closure. In the NTD case mothers the mean (+/- SD) levels were not significantly lower than in control mothers: folate, 4.13 +/- 2.36 versus 4.28 +/- 2.52 ng/ml; vitamin B12, 482.8 +/- 161.1 versus 520.3 +/- 191.9 pg/ml; and retinol, 51.2 +/- 17.0 versus 50.5 +/- 16.9 micrograms/dl. After adjustment for age of the specimen, gestational age at which the specimen was drawn, maternal age, and maternal employment status, the odds ratios for being a case mother were 1.00 (95% confidence interval (CI) 0.91 to 1.10) for folate, 1.05 (95% CI 0.92 to 1.19) for vitamin B12, and 0.99 (95% CI 0.88 to 1.10) for retinol. Excluding NTD cases with known or suspected causes unrelated to vitamins, restricting the analyses to interviewed subjects, and excluding subjects whose specimens were collected after 15 gestational weeks confirmed that NTD case and control vitamin levels did not differ significantly. This population-based investigation in a low rate area demonstrated no relationship between maternal serum folate, vitamin B12, or retinol levels during pregnancy and the risk of NTDs.

Adult↗
PubMed1991

Computed tomography scan in the early detection of silicosis.

We evaluated the ability of both the conventional and high resolution computed tomography (CCT and HRCT, respectively) scans of the thorax to detect early silicosis in subjects exposed to silica dust in the mines and foundries of Québec for an average of 29 +/- 2 yr. The study was limited to subjects with chest radiograph (CR) of the International Labor Organization (ILO) Categories 0 or 1 as determined independently a priori. All subjects had a standard high-kilovoltage posteroanterior and lateral CR, a set of 10 to 15 1 cm collimation CCT scans, and a set of three to five 2 mm collimation HRCT scans in the upper, middle, and lower lung fields. For each CR and sets of CT scans, readings were done independently by four experienced readers. For small opacities of the lung parenchyma on CR, 32 of the 51 subjects were normal (Group A), six were indeterminate (Group B), and 13 were abnormal (Group C). By the combined readings of HRCT and CCT, 13 of the subjects (40%) in Group A were abnormal (p less than 0.001); four of the subjects in Group B were abnormal, and in Group C, one subject was normal, one indeterminate, and 11 (84%) abnormal. For confluence of small opacities, 48 of the 51 subjects were negative (Group 0), and three were positive (Group 1) on the CR. By the CT scan, 42 of the 48 subjects in Group 0 were negative, and the three subjects in Group 1 were positive; thus the CT scan added six positive cases with confluence of small opacities (six of 48, 12.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cleavage of folates during ethanol metabolism. Role of acetaldehyde/xanthine oxidase-generated superoxide.

Although folate deficiency and increased requirements for folate are observed in most alcoholics, the possibility that acetaldehyde generated from ethanol metabolism may increase folate catabolism has not been previously demonstrated. Folate cleavage was studied in vitro during the metabolism of acetaldehyde by xanthine oxidase, measured as the production of p-aminobenzoylglutamate from folate using h.p.l.c. Acetaldehyde/xanthine oxidase generated superoxide, which cleaved folates (5-methyltetrahydrofolate greater than folinic acid greater than folate) and was inhibited by superoxide dismutase. Cleavage was increased by addition of ferritin and inhibited by desferrioxamine (a tight chelator of iron), suggesting the importance of catalytic iron. Superoxide generated from the metabolism of ethanol to acetaldehyde in the presence of xanthine oxidase in vivo may contribute to the severity of folate deficiency in the alcoholic.

Acetaldehyde↗
PubMed1989

The ileum is the major site of absorption of vitamin B12 analogues.

Non-cobalamin vitamin B12 analogues constitute a significant percentage of total corrinoids in human serum. The source and means of absorption of analogues and their significance are largely unknown. We studied the sites of production and absorption of B12 analogues by measuring serum vitamin B12 and analogues in 93 patients with various gastrointestinal diseases: pernicious anemia (PA), ileal resections, ileitis, Crohn's colitis, ulcerative colitis, and irritable bowel syndrome (IBS). Patients with PA had normal analogue levels that were unchanged or that rose during cessation of B12 administration. Patients with IBS, Crohn's colitis, ulcerative colitis, and total colectomies had B12 analogues in the normal range. Patients with diseased or resected ileums had low B12 and analogues. These data suggest that serum B12 analogues are absorbed in the ileum by a mechanism independent of intrinsic factor, and that colonic bacteria and endogenous metabolism of vitamin B12 do not contribute significantly to their level.

Anemia, Pernicious↗
PubMed1987

Nutritional factors in epidemic Kaposi's sarcoma.

The role of nutritional factors in the management of acquired immunodeficiency syndrome-related, or epidemic, Kaposi's sarcoma (EKS) is complex, since there are known interactions between malnutrition, immunodeficiency, and cancer. Malnutrition is a well-established cause of immune aberrations, which are seen in deficiencies of both protein and energy, as well as specific nutrients, particularly trace metals. Conversely, malnutrition is a common result of both cancer and immunodeficiency. Cancer patients without an obviously immunological pathogenesis frequently have malnutrition and cachexia, mainly as a result of a decreased dietary intake and poorly defined host-tumor interactions (commonly labeled "hypermetabolic"). Patients with primary immunodeficiency syndromes similarly experience a triad of diarrhea, malabsorption, and weight loss, which are responsible for the development of malnutrition. This triad is common in patients with AIDS, with or without the presence of Kaposi's sarcoma. The specific mechanisms of these interactions in EKS patients are largely unexplored; although some can be explained by the enteropathic effects of opportunistic infections, others can not. Some investigators have advocated careful nutritional evaluation of all AIDS patients, with vigorous nutritional support to be provided where assessment reveals suboptimal nutritional status. Specific nutrient deficiencies have been reported, of which selenium may be the most interesting; preliminary data indicate that it may be responsible for a malnutrition-related immunodepression seen with AIDS. Such supportive measures may significantly improve symptomatic relief, but there is as yet no evidence that they alter the course of the disease.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Is there a "gold standard" for human serum vitamin B12 assay?

In a study from four laboratories using two commercial vitamin B12 radioassays (impure hog intrinsic factor concentrate containing both intrinsic factor and R binders (IF + R) to measure total corrinoids and the same concentrate presaturated with cobinamide (Cbi) to block B12 binding sites on R binder (IF + R + Cbi) to measure only cobalamins), the rank order of results was generally the same. The concordance between the two tests for classifying sera as normal or deficient was 91% in 311 serum samples. Three percent of sera below the "true B12" (B12 binding to IF + R + Cbi) normal cut-off point were not below the cut-off point for normal "total B12" (B12 binding to IF + R); 6% of sera below the total B12 normal cut-off point were not below true B12 cut-off point. The correlations between Euglena gracilis and the radioassays were 0.80 and 0.83 in the 50 serum samples that also had E. gracilis serum vitamin B12 levels. Lactobacillus leichmannii serum vitamin B12 levels were determined in 49 of the 311 serum samples and results were comparable with results obtained by four radioassay binder systems: IF + R, IF + R + Cbi, highly purified hog IF, and saliva R binder. The closest correlate with L. leichmannii was radioassay using IF + R as binder (r = 0.93), then IF + R + Cbi (r = 0.92), pure IF (r = 0.80), and pure R (r = 0.73). The key to reliable results appears not to reside in a particular assay but rather in determining for each assay its own range of results in participants determined clinically and morphologically normal vs. participants with deficient vitamin B12 (with B12 deficiency defined independently of a serum B12 assay). When laboratory assay results differ from clinical judgment, further evaluation is the appropriate course. There is no "gold standard" for human serum vitamin B12 assay.

Biological Assay↗
PubMed1983

Transcobalamin II deficiency associated with unusual bone marrow findings and chromosomal abnormalities.

A female infant presented at seven weeks of age with failure to thrive, progressively severe pancytopenia, hypogammaglobulinemia and, mucosal ulceration. Bone marrow morphology showed severed megaloblastic changes in the myeloid series with a shift to the left and an increased number of blasts with abnormal morphology. Erythroid precursors and megakaryocytes were markedly decreased. Cytogenetic studies showed marked aneuploidy and increased chromosomal breakage. Treatment with high doses of vitamin B12 resulted in a dramatic clinical response with hematological values becoming normal. The patient's serum showed absence of transcobalamin II, and very little TC I and TC III binding. The patient's parents had only half the lower limits of normal transcobalamin II. QUSO G-32 was used for separation of transcobalamins, and the results were confirmed by Sephacryl S-300. This case illustrates the usefulness of QUSO in the rapid diagnosis of transcobalamin II deficiency.

Blood Cell Count↗
PubMed1981

Detection of a milk factor that facilitates folate uptake by intestinal cells.

Folate binding proteins in milk were tested for their effect on folate absorption. The uptake of bound folate by isolated mucosal cells from the rat small intestine was twice that of free folate and differed from it in being more effective with progression down the small intestine, in not being affected by glucose or Dilantin, in having a higher pH optimum, and in being affected by calcium concentration. This milk factor may enhance folate absorption in infants, whose risk of folate deficiency is high.

Animals↗