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J C Crawhall

Publications and source records attributed to J C Crawhall.

At least 19 recordsLinked to original sources
PubMed1989

Determination of encainide and its metabolites by high-performance liquid chromatography.

Encainide (ENC) and its metabolites O-demethylencainide (ODE), 3-methoxy-O-demethylencainide (MODE), N-demethylencainide (NDE) and bis-N,O-demethylencainide (NODE) have been measured by two HPLC procedures. The method of Mayol using a mu Porasil column with ethanol-water-methanesulphonic acid as mobile phase was not able to separately measure NODE and NDE in plasma. A new method is described using a mu Bondapak Phenyl column with acetonitrile-phosphate buffer (0.05 M, pH 7.5) that yields satisfactory separation of ENC and its metabolites. NODE was not identified as a metabolite in 23 patients analysed.

Anilides↗
PubMed1989

Catecholamine-secreting paraganglioma of glomus jugulare region.

A 43-year-old woman had clinical and biochemical evidence of a secreting paraganglioma of the glomus jugulare region. Catecholamine secretion was exacerbated during embolization of the tumor before surgery and resulted in a life-threatening vasomotor attack. Preoperatively, pharmacologic blockade of excessive catecholamine secretion with prazocin controlled her blood pressure, tachycardia, and symptoms. The tumor was resected and its catecholamine content measured. This case is reported to stress the importance of adequate preoperative assessment of patients with paragangliomas of the head and neck. The extreme rarity of catecholamine-secreting tumors of this region should not lead us to underestimate the morbidity and mortality of such patients undergoing surgery or any other invasive procedure whether the diagnosis is confirmed or only suspected.

Adult↗
PubMed1988

Measurement of biological disulfides by postcolumn sulfitolysis following separation by HPLC.

We developed a method to measure disulfides which is applicable to biological fluids. It consisted of two parts. First, certain thiols and disulfides were separated by HPLC. Second, the eluted materials were submitted to postcolumn reaction with 2-nitro-5-thiosulfobenzoate in the presence of sulfite. The resultant yellow product, 2-nitro-5-thiobenzoate, was measured by its absorbance at 412 nm. We determined the elution characteristics of the thiols and disulfides derived from cysteine, glutathione, alpha-mercaptopropionylglycine (Thiola), and cysteamine. Penicillamine and its disulfide did not react. Cystine in the urine of 22 cystinuric patients, measured by this method, was compared with results obtained by automatic amino acid analysis.

Chromatography, High Pressure Liquid↗
PubMed1988

Molecular forms of atrial natriuretic peptides in dog atrium and plasma.

The level of immunoreactive ANP (iANP) as determined by radioimmunoassay, exhibits a fairly even distribution throughout the canine atria. However, the maximal concentration was found in the appendages of both the left and right atrium, and the level was significantly higher on the left side in all analyzed localizations. Reverse-phase HPLC of atrial extracts, coupled with RIA, revealed the presence of three iANP fractions. The dominant fraction (65% of iANP) has an estimated molecular weight 16,300, showing that it corresponds to the hormone precursor. By contrast, in the plasma extract, 92% of iANP coelutes with synthetic human ANP99-126, thus confirming the structural identity of dog and human ANP.

Animals↗
PubMed1988

Atrial natriuretic peptide: blood levels in human disease and their measurement.

The atrial hormonal system consists of 126 amino acid-containing prohormone (proANP) stored in the secretory granules of atrial myocytes and 28 amino acid-containing hormone (ANP) that is secreted into the bloodstream in response to raised atrial pressure. ANP participates in the homeostasis of body fluid volume through its main receptor-mediated effects; natriuresis, inhibition of renin and aldosterone secretion, and vasodilation. It counteracts the renin-angiotensin system with the putative primary role of regulating the circulating blood volume. Although in man, the physiologic volume stimuli lead to relatively modest increases of ANP secretion, its plasma level undergoes striking changes in pathology. Marked elevations in conditions accompanied by fluid retention, most conspicuously in heart failure and renal failure, have been explained as a compensatory reaction to volume overload. The recent data suggest a decreased target organ responsiveness as one of the causes of a relative inefficiency of the high circulating levels of ANP in inducing an appropriate natriuresis in these volume overload conditions. The well established radioimmunoassay and the more recent methods of plasma ANP measurement are reviewed, and the authors' results with a commercial RIA are presented.

Animals↗
PubMed1988

Renal dose response and pharmacokinetics of atrial natriuretic factor in dogs.

The present studies investigated the dose-plasma level-response relationships with the use of increasing doses of atrial natriuretic factor [ANF-(99-126)] administered by constant infusion in conscious dogs. The preinfusion plasma immunoreactive ANF increased 12, 19, 23, and 35 times during 45-min consecutive infusions of 50, 75, 125, and 175 ng.kg-1.min-1, respectively. Over this pharmacological range, natriuresis increased linearly with the infused dose (r = 0.99, n = 5) to a maximum response of +1,550%, despite the significant gradual fall of blood pressure, which attained a minimum of 83 mmHg (-26%) at 125 ng.kg-1.min-1. There was no change of glomerular filtration rate (GFR) or renal plasma flow at any dose. A very similar renal response was found in 13 other dogs infused with the highest dose only in which the pharmacokinetic parameters of ANF-(99-126) were estimated. Metabolic clearance rate during the infusion was 1.09 +/- 0.19 l/min. The postinfusion decay curve of plasma immunoreactive ANF was best described by a biexponential function. Plasma disappearance half time was 1.44 min during the rapid phase and 10.3 min during the slow phase of elimination. The results show that 1) natriuretic response to ANF in the pharmacological range is dose dependent and occurs despite a pronounced hypotension, 2) increase in GFR is not a prerequisite of ANF-induced natriuresis, and 3) ANF is rapidly eliminated from the circulation, suggesting an intensive uptake and/or degradation in the target tissues.

Animals↗
PubMed1987

Systemic mastocytosis: management of an unusual case with histamine (H1 and H2) antagonists and cyclooxygenase inhibition.

A patient with urticaria pigmentosa and systemic mastocytosis developed hypotension following indomethacin administration. He then developed further episodes not related to indomethacin. Based upon the experience of others with the management of patients with systemic mastocytosis who showed exceptional reaction to cyclooxygenase inhibition, it was decided to treat him with H1 and H2 blockade followed by aspirin, another cyclooxygenase inhibitor. The procedure was carried out under careful observation with cardiac monitoring. After 160 mg of aspirin, he developed hypotension, tachycardia, and flushing accompanied by difficulty of breathing and headache. A vasoconstrictor drug (levarterenol) was administered. The patient's symptoms subsided, and after 1 hour aspirin was again administered, this time with no side effects. The dosage was increased to 975 mg every 6 hours, and he has had no further hypotensive episodes on this regime for 2 years. Cyclooxygenase inhibition, combined with H1 and H2 blockade, is an effective treatment for this condition, but for these patients initiation of aspirin therapy should be carried out with extreme care.

Cimetidine↗
PubMed1987

Cystinuria--an experience in management over 18 years.

Data on 23 patients with cystinuria are presented. These have been analysed for age, sex and the incidence of surgical procedure. Urinary amino acid data have been analysed to confirm homozygosity which was achieved in all but one of the cases. Guidelines are presented concerning surgical and medical management of the patients, and some results of percutaneous lithotripsy are presented.

Adolescent↗
PubMed1985

Separation of biological variant insulin molecules from different species by reversed-phase high-performance liquid chromatography (HPLC).

Three different isocratic systems for the separation by reversed-phase high-performance liquid chromatography (HPLC) of different species of insulin have been investigated. The effect of different solvent compositions and temperatures on elution time and resolution have been studied. These studies have been used to devise a method for reversed-phase liquid chromatographic separation of bovine, porcine, and human insulin, as well as the A and B chains of bovine insulin. The method can also be used for the separation of the various products of the iodination of porcine insulin. 125I-A14 tyrosine-labeled porcine insulin can be readily separated from nonlabeled porcine insulin and from other iodinated constituents of the mixture. A flow-though gamma-counting system that was designed for this work is described.

Animals↗
PubMed1985

A review of the clinical presentation and laboratory findings in two uncommon hereditary disorders of sulfur amino acid metabolism, beta-mercaptolactate cysteine disulfideuria and sulfite oxidase deficiency.

Two hereditary disorders of sulfur amino acid metabolism, beta-mercaptolactate-cysteine disulfideuria and sulfite oxidase deficiency, were described twenty years ago. Other examples of these disorders have been limited to about 5 of each in the world literature since then. Reasons for the apparent rarity of these conditions are discussed and the analytical procedures to identify them are reviewed. The detection of the first depends on the positive result of a cyanide-nitroprusside test followed by positive identification of the specific mixed disulfide. The enzyme mercaptopyruvate sulfur transferase has been shown to be deficient. In the second disorder of sulfite oxidase deficiency, the clinical presentation with progressive dystonia and dislocated lenses in an infant should suggest further laboratory investigations for this disorder which would not be detected by conventional laboratory screening procedures. Laboratory diagnosis can be obtained by use of the Merckoquant sulfite test on a fresh urine sample. Quantitative thiosulfate and taurine measurements can also be made. Positive identification of the specific amino acid S-sulfo-L-cysteine should also be made. The enzyme sulfite oxidase is missing from such organs as liver, kidney and brain. This latter condition may also be associated with xanthinuria. For this combined disorder of sulfite oxidase and xanthine oxidase, a deficiency of a molybdenum-containing cofactor has been demonstrated.

Adolescent↗
PubMed1984

Methods for assaying D-penicillamine in a clinical setting.

Penicillamine disulfides have been analysed by automatic amino acid analysis. Because the free thiol reacts poorly with ninhydrin, other detection methods are preferred, particularly high pressure liquid chromatography using an electrochemical detector or gas chromatography with a flame ionization detector. Pharmacokinetic studies have now been reported using these techniques. With patients on established penicillamine regimes, the concentration of free penicillamine in the plasma has been found to vary between 4 and 20 microM depending on dosage and time of administration. Disulfide concentration is higher than this by a factor of 3 or 4 and an even greater quantity is attached to plasma and tissue proteins.

Arthritis, Rheumatoid↗
PubMed1984

Circulating immune complexes in patients with rheumatoid arthritis and the effect of penicillamine in vitro.

Protein precipitated from the sera of 15 patients with rheumatoid arthritis (RA) by increasing concentrations of polyethylene glycol 6000 (PEG) was compared with that from 20 normal controls. The wide range of precipitable protein obtained was only significantly different for the two groups when a 4% PEG concentration was used. To increase the discrimination of the procedure, the precipitated protein was measured for IgG, IgM, C3 and C4 using immunospecific antisera and laser nephelometry. The data obtained from each of these procedures did not increase the specificity of the technique as a means of distinguishing between patients and controls. As part of an investigation of the effect of penicillamine on immune complexes, penicillamine was incubated at 37 degrees C for 24 and 48 h with sera containing immune complexes from RA patients. When the immune complexes were precipitated with PEG, it was found that incubation, by itself, reduced the amount of PEG precipitable protein. The results of in vitro incubation with penicillamine were very variable.

Antigen-Antibody Complex↗
PubMed1983

Separation and quantitation of oxypurines by isocratic high-pressure liquid chromatography: application to xanthinuria and the Lesch-Nyhan syndrome.

An isocratic HPLC technique has been developed for the separation and measurement of urine and plasma oxypurines in a patient with xanthinuria. The case history and laboratory data are presented. Xanthine excretion was 172 mg/g creatinine and hypoxanthine was 45 mg/g creatinine. Uric acid was too small to be measured but uricase determination showed only 3 mg/24 hr. Serum oxypurine analysis showed hypoxanthine 0.87 mg/dl and xanthine 0.35 mg/dl. Uric acid was not seen in this patient's serum but could be readily measured in normal control subjects. The technique can also be used to separate nucleotides from purine bases, and we have demonstrated its application to the measurement of erythrocyte hypoxanthine guanine phosphoribosyl transferase and adenine phosphoribosyl transferase in a kindred associated with the Lesch-Nyhan syndrome.

Chromatography, High Pressure Liquid↗