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Biomedical subjects

T R Koch

Publications and source records attributed to T R Koch.

At least 73 records · Page 4Linked to original sources
PubMed1987

Abnormalities of fasting serum concentrations of peptide YY in the idiopathic inflammatory bowel diseases.

Peptide YY has been localized within human ileocolonic endocrine cells and may contribute to the regulation of gastric secretion and gastric emptying in man. Since our previous studies had shown decreased colonic concentrations of peptide YY in the idiopathic inflammatory bowel diseases, a specific radioimmunoassay was used to measure fasting serum concentrations of peptide YY in healthy controls and in patients with adenocarcinoma of the rectum, idiopathic chronic active liver disease and hepatic cirrhosis, ulcerative colitis, and Crohn's disease. In healthy controls and in patients with adenocarcinoma of the rectum, serum concentrations of peptide YY ranged from 50 to 260 pg/ml. Serum concentrations of peptide YY in patients with hepatic cirrhosis ranged from 59 to 717 pg/ml. Serum concentrations of peptide YY in patients with ulcerative colitis were similar to healthy controls. In patients with Crohn's disease, serum concentrations of peptide YY were less than 50 pg/ml in three patients who had had a previous proctocolectomy, and were more than 260 pg/ml in 14 patients who had had previous resection of more than 48 cm of ileum or presently had symptomatic Crohn's disease subsequently requiring surgical resection of a total of more than 75 cm of ileum. These results suggest that most circulating peptide YY is released from the colorectal region. Hepatic cirrhosis, previous ileal resection, and symptomatic Crohn's disease were associated with elevation of fasting serum peptide YY. The mechanism of increased fasting serum peptide YY in patients with Crohn's disease could be the loss of an ileal inhibitory factor or possibly an increased release of colonic peptide YY in response to fat malabsorption. The effect of alteration of serum peptide YY concentrations on the pathophysiology of Crohn's disease is yet unknown.

Adenocarcinoma↗
PubMed1987

Bias and precision of cholesterol analysis by physician's office analyzers.

We studied the bias and precision of serum cholesterol analysis by physician's office analyzers. Total imprecision (CV range, %) for analysis of serum pools was: Abbott Vision 1.5%-1.9%; Ames Seralyzer 3.9%-4.5%; BMD Reflotron 2.3%-3.8%; Chrometrics Cholesterol Test System 2.3%-2.8%; Kodak DT-60 1.6%-2.2%. The Ames Seralyzer exhibited an excessive between-run component of variation. We collected, from 109 volunteers, samples of venous serum, heparin-treated whole blood, heparin-treated plasma, and fingerstick whole blood, and analyzed each type (where possible) with each system; serum was also analyzed in duplicate (by a proposed Reference Method) at the Centers for Disease Control. For assays with serum, the BMD Reflotron and Kodak DT-60 exhibited negative bias. All systems gave lower results for plasma and whole blood than for serum. All systems except the Kodak DT-60 were less precise for analysis of patients' sera than for analysis of serum pools; between-specimen variables may influence the results of these systems.

Cholesterol↗
PubMed1986

Clinical and analytical evaluation of kits for measurement of creatine kinase isoenzyme MB.

We studied the analytical and clinical performance of six methods for creatine kinase (EC 2.7.3.2) isoenzyme MB (CK-MB): three immunoassays (Behring, Hybritech, and International Immunoassay Labs); one immunoinhibition assay (Roche); one immunoinhibition/column method (Du Pont); and one electrophoretic method (Beckman). Between-day precision for all kits was poor at the upper reference limit. All methods gave results linearly related to CK-MB concentration and all were free from CK-MM, CK-BB, and adenylate kinase interference. Only the Du Pont method was adversely affected by atypical isoenzymes. For diagnosis of acute myocardial infarction in a coronary care population (n = 40; prevalence = 45%), all methods were approximately 95% efficient, when appropriate reference criteria were used. Some manufacturers fail to provide data for an appropriate (acutely ill, non-infarct) reference population; decreased diagnostic specificity may result from use of reference ranges based on results for healthy subjects. Expression of CK-MB as a percent of total CK degrades efficiency unless total CK is markedly increased.

Adenylate Kinase↗
PubMed1985

Distribution and quantitation of immunoreactive gut neuropeptides in piebald mice and their normal littermates.

Piebald mice inherit congenital megacolon associated with distal aganglionosis. To study the distribution of intrinsic peptidergic nerves in the gut of piebald mice and their normal littermates, we used specific radioimmunoassays to measure the tissue concentrations of the following immunoreactive neuropeptides: vasoactive intestinal peptide (VIP), peptide histidine-isoleucine (PHI), [Met]enkephalin (Enk), substance P (SP), and bombesin-like intestinal peptide (BLIP). In the normal littermates, all neuropeptide concentrations were significantly greater in the colon than in the proximal gut. SP, Enk, VIP, PHI, and BLIP levels were all decreased in the distal colon of piebald mice as compared to normal littermates, SP, BLIP, and Enk levels were also decreased in the dilated proximal colon of piebald mice. These results suggest that there are abnormalities in the peptidergic innervation of the proximal and the distal colon in piebald mice. The abnormalities localized to the proximal colon of piebald mice may be related to functional obstruction of the colon.

Animals↗
PubMed1984

Histofluorescent and radioenzymatic analysis of colonic catecholamines in man.

Colonic tissues from patients with ulcerative colitis (UC), ileal tissue from patients with Crohn's disease (CD), and other ileocolonic disorders were radioenzymatically assayed for norepinephrine (NE) and dopamine (DA). These assays showed that the NE content of UC colon ranged from 3.2 to 4.3 ng/mg wet tissue, while in other colonic disorders it ranged from 3.0 to 5.3 ng/mg. Similarly, the DA content of UC colon ranged from 0.42 to 1.17 ng/mg wet tissue, while for other colonic disorders it ranged from 0.48 to 0.89 ng/mg. The same tissues were examined histochemically using glyoxylic acid condensation of catecholamines (CA) for the semi-quantitation of CA-containing structures. Examination of these structures revealed an apparent increase in their staining intensity in the myenteric plexus in ulcerative colitis as compared to other colonic disorders. Morphologically, the CA-containing structures of the colon appeared to be increased in UC, but determination of the NE and DA concentrations in colonic samples revealed no statistically significant differences in comparable regions of the colon.

Colitis, Ulcerative↗
PubMed1984

Lack of interference with creatinine assays by four cephalosporin-like antibiotics.

Some cephalosporin-like antibiotics have been shown to interfere with creatinine assays performed by the commonly used Jaffe methods. The authors show that four new drugs of this type--moxalactam, cefoperazone, cefotaxime, and ceftazidime--do not interfere with this test. A table is presented summarizing all literature data regarding interference with creatinine assays of cephalosporin-like drugs.

Cefoperazone↗
PubMed1983

Detection of central nervous system metastasis with cerebrospinal fluid beta-2-microglobulin.

Beta-2-microglobulin determinations in cerebrospinal fluid (CSF) of patients with leukemia, lymphoma, and oat cell carcinoma were performed to evaluate the utility of this test in early detection of metastasis to the central nervous system (CNS). In the presence of CNS disease, significantly higher levels (P less than 0.001) were found than in normals or patients without CNS disease. Serial measurements were performed on two patients, and in all cases beta-2-microglobulin became elevated coincident with CNS relapse, and returned to normal as remission was achieved. Serial testing of CSF beta-2-microglobulin, in patients with cancers known to invade the CNS, should facilitate prompt treatment of CNS metastasis.

Beta-Globulins↗
PubMed1982

Cefoxitin falsely elevates creatinine levels.

Cefoxitin sodium has been found to act like creatinine in assays for creatinine used by many hospitals. Our in vitro results show that cefoxitin causes an apparent rise in the serum creatinine level; the magnitude of the increase depends on the assay method and the concentration of cefoxitin. Results varied from 1.5 to more than 8.5 times the normal serum creatinine level. Published data from studies of human volunteers show the same effect. In patients with normal renal function, the serum creatinine test is reliable two to four hours following cefoxitin infusion and in mild to moderate renal failure (glomerular filtration rate greater than 30 mL/min), six to eight hours. In severe renal failure, the serum creatinine determination is unreliable. Measurement of urinary creatinine employs similar assays, thus making estimation of creatinine clearance unreliable when the patient is receiving cefoxitin.

Adult↗
PubMed1982

Rapid quantitation of serum immunoglobulins with a miniature centrifugal analyzer.

For these quantitative turbidimetric assays for immunoglobulins IgG, IgA, and IgM in serum, the reagents used are commercially available in kit form. The two-point assays are performed with a miniature centrifugal analyzer (GEMENI, Electro-Nucleonics, Inc.). The reading taken 5 s after mixing is used to correct for specimen turbidity. Run-to-run precision (CV) was typically 5% (range: 3.0-8.7%). Excellent correlation with radial immunodiffusion was observed for each test (r greater than 0.98 for each test). The dynamic range of each test extends above and below the reference-interval ranges.

Centrifugation↗
PubMed1981

Lead accumulations in brain, blood, and liver after low dosing of neonatal rats.

Newborn rat pups were treated in seven groups: Group 1, the control, was untreated and killed at birth (day 1); Groups 2, 3, and 4 were treated on postnatal days 1 through 10 with respectively saline or lead acetate, 5.0 mg/kg and 7.5 mg/kg body weight; Groups 5, 6, and 7 were treated with the same respective dosages on days 11 through 20. Cerebellum, cerebral cortex, brainstem plus hippocampus, liver, and blood were analyzed for lead. Neonatal rats killed at birth all contained some lead, the cerebellum having the highest concentration. Tissue from most treated groups accumulated lead in a dose-dependent manner. A comparison of lead concentrations between the organs of rats dosed days 1-10 and rats dosed days 11-20 indicated that the latter accumulated less lead per gram of tissue (p less than 0.05) than their younger litter mates.

Animals↗
PubMed1981

Crohn's ileitis and ileocolitis: a study of the anatomical distribution of recurrence.

The records were reviewed of 56 consecutive patients with Crohn's disease (CD) who had had an ileocolonic anastomosis formed during surgical resection for Crohn's ileitis or ileocolitis. Twenty-seven patients (48%) were found to have radiological, pathological, or surgical evidence of recurrent CD. Of 24 patients with a diagnosis of Crohn's ileitis at initial surgery, 9 were found to have recurrent disease proximal to the anastomotic site. Of 32 patients with ileocolitis, 11 had recurrent disease proximal and distal to the anastomosis. Contrary to many prior reports, recurrent CD is not always located proximally to a surgical anastomosis. The distribution of recurrent CD tends to be a statistically significant function of the initial anatomical location with proximal recurrence found most often in Crohn's ileitis, while proximal and distal recurrence is associated with Crohn's ileocolitis (X2 = 4.5 P less than 0.05).

Adolescent↗
PubMed1981

Evaluation of the new Beckman electrophoretic method for CK-MB: comparison with ion exchange chromatography and investigation of a reference outpatient population.

We evaluated the performance of a CK isoenzyme kit utilizing agarose electrophoresis with fluorescence scanning of an overlay paper rather than the gel. We compared this method to ion exchange chromatography with mini-columns of DEAE Sephadex using samples from hospitalized patients and from a reference population of ambulatory outpatients with common, chronic medical conditions. The detection limit, precision and linearity of the electrophoretic method were acceptable, but the method overestimated CK-MB, requiring a different reference range for clinical application. There were inter-racial differences within the reference population for total CK and for the percent of CK-MB using either method. We discuss the significance of our findings with respect to clinical decision limits for CK-MB.

Adult↗
PubMed1981

Feasibility of measuring free and total bilirubin electrochemically in serum.

Bilirubin undergoes irreversible reduction at the hanging-mercury-drop electrode in tris(hydroxymethyl)methylamine buffer (0.1 mol/L, pH 8.5). Peak current is linearly related to concentration in the range 0-1 mg/L. The half-wave potential of -1.32 V vs the saturated calomel electrode is little affected by pH, whereas peak current increases with pH to pH 9.5, then decreases rapidly. Exposing the test solution to light causes the peak current to decline at a rate proportional to concentration. Albumin-bound bilirubin is electrochemically inactive, so free bilirubin can be measured in the presence of bilirubin-saturated albumin. Serum total bilirubin can be measured after much of the protein is precipitated by adding methanol. Results for serum bilirubin as measured electrochemically (y) in 20 methanolic filtrates of serum compared well with the Jendrassik-Grof Method (x) in preliminary studies: y = 0.981x -0.311; r = 0.9716. We discuss the possible mechanism of the reduction process and potential clinical applications. Polarographic measurement of bilirubin and bilirubin-binding capacity is feasible and may be advantageous as compared with existing techniques.

Bilirubin↗
PubMed1981

Measurement of serum lipase activity with the oxygen electrode.

We describe the measurement of lipase (triacylglycerol lipase; EC 3.1.1.3) in serum by continuous monitoring of relative rates of oxygen consumption with a polarographic oxygen electrode. The reactions described by Proelss and Wright (Clin. Chem. 23: 522-531, 1977) are used: trilinolein, with lipase catalysis, yields linoleic acid, which reacts with oxygen in the presence of lipoxygenase. Lipase activity is measured by comparing the zero order reaction rate of the specimen with that obtained with linoleic acid standards. Results for lipase (y) correlated well with those by the copper-soap method of Myrtle and Zell (x) (Clin. Chem. 21: 1469-1473, 1975); y = 0.33x - 11; r = 0.98; n = 34. Results are unaffected by specimen dilution, and the standard curve is linear to 520 U/L. Day-to-day precision (CV) is 10.4% for normal activities, 6.1% for above-normal activities. We believe the method offers a precise, practical approach to lipase analysis.

Blood Chemical Analysis↗
PubMed1979

Synthesis of chromophoric, spin label enzyme substrates useful for cryoenzymology.

The spin label nitroxide derivative 3-(2,2,5,5-tetramethylpyrroline-1-oxyl)-propen-2-oic acid has been synthesized and characterized by chemical methods. It is a useful intermediate in the preparation of a new class of chromophoric spin label substrates for enzyme studies, as shown by the synthesis of O-3-(2,2,5,5-tetramethylpyrroline-1-oxyl)-propen-2-oyl-L-beta-phenyllactic acid, a specific ester substrate of bovine pancreatic carboxypeptidase A (peptidyl-L-amino acid hydrolase; EC 3.4.12.2). Kinetic parameters of the esterolytic reaction are conveniently determined by UV spectrophotometric methods, and a reaction intermediate can be stabilized in fluid cryosolvent mixtures at subzero temperatures. Results are presented of preliminary electron spin resonance studies to demonstrate that structural relationships of the spin label substrate in a catalytically active configuration to active site residues can be determined for this low temperature-stabilized reaction intermediate. This substrate thus demonstrates the utility of this new class of spin label derivatives for characterization of enzyme reaction intermediates stabilized by cryoenzymologic techniques.

Animals↗
PubMed1979

A column chromatographic method for the determination of 5-hydroxytryptamine (serotonin) and 5-hydroxyindole acetic acid in cerebrospinal fluid.

A method is described for measurement of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in cerebrospinal fluid. 5-HT and 5-HIAA are isolated from columns of Biorex BR-70 and Sephadex G-10 with recoveries of 85 and 89% respectively. The indoles are quantitated by fluorometric measurement of the ortho-phthaldialdehyde derivatives in acidic solution. Correction for interfering 5-methoxytryptamine and 5-methoxyindole acetic acid is accomplished by a second measurement at alkaline pH. Thin-layer chromatographic analysis of column eluates has revealed no other interfering indoles in the 5-HT and 5-HIAA fractions. Preliminary results in normal cerebrospinal fluid samples have been in the ranges 10--60 ng/ml 5-HIAA and 0--13 ng/ml 5-HT.

Chromatography, Gel↗