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Biomedical subjects

A Brock

Publications and source records attributed to A Brock.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Cholinesterase in healthy adults. Significance of sex, age, weight and height for activation of P-cholinesterase].

On the basis of an investigation og 193 healthy adults without occupational exposure to known cholinesterase-inhibitors, it was found that in addition to being related to the sex and ChE-fenotype, the cholinesterase activity is correlated to the weight and height of the individual concerned. Compared with the great interindividual variations, the intraindividual variations are of marginal significance for the total variation. Where dissimilar groups are concerned, comparison of the cholinesterase values corrected for variations which may be ascribed to the factors: sex, ChE-fenotype, weight and height is recommended.

Adult↗
PubMed1990

Immunoreactive plasma cholinesterase (EC 3.1.1.8) substance concentration, compared with cholinesterase activity concentration and albumin: inter- and intra-individual variations in a healthy population group.

Substance concentrations of plasma cholinesterase (EC 3.1.1.8) were measured in 94 healthy individuals without occupational exposure to known inhibitors (six samples from each individual). Immunoreactive cholinesterase substance concentrations showed an inter-individual variation corresponding to CVtotal = 22% (mean: 5.01 mg/l, SD: 1.11 mg/l). Intra-individual variations of immunoreactive cholinesterase substance concentration were correlated (r = 0.36) to intra-individual variation of albumin. Estimated by a repeated-measures analysis of variance, the observed intra-individual variation of cholinesterase substance concentration corresponded to CV = 8.8% (SD: 0.44 mg/l), which together with a CVerror = 6% (within and between runs), implies a biological intra-individual variation of cholinesterase substance concentration corresponding to CVintra = 6.4%. Specific catalytic activity (kU/mg immunoreactive cholinesterase) was influenced by the ChE-1 phenotype (phenotype U: 1.58 kU/mg, phenotype UA: 1.22 kU/mg), but not by body weight, height, age, and sex. Observed intra-individual variation of specific catalytic activity corresponded to 6.4% (SD: 0.10 kU/mg), which together with an estimated CVerror = 6.2% implies the biological intra-individual variations of specific catalytic cholinesterase activity to be insignificant. The insignificant CVintra makes specific catalytic cholinesterase activity a rational quantity for evaluation of unexpected fluctuations of cholinesterase activity concentrations.

Adult↗
PubMed1990

Enzyme immunoassay of human cholinesterase (EC 3.1.1.8). Comparison of immunoreactive substance concentration with catalytic activity concentration in randomly selected serum samples from healthy individuals.

We developed an enzyme immunoassay (ELISA) for quantitation of plasma cholinesterase substance concentrations in native plasma or serum samples. The ELISA assay is based on polyclonal (rabbit) antihuman cholinesterase and a highly specific monoclonal (mouse) antibody, with a commercially available peroxidase-conjugated (rabbit) antibody directed against mouse immunoglobulins as the signal carrier. The detected serum cholinesterase substance concentrations (mean: 4.51 mg/l, SD: 0.90 mg/l) in randomly selected serum samples from 33 healthy individuals were closely and linearly related to the corresponding catalytic activity concentrations.

Calibration↗
PubMed1990

Plasma cholinesterase activity in a healthy population group with no occupational exposure to known cholinesterase inhibitors: relative influence of some factors related to normal inter- and intra-individual variations.

Inter-individual variations of plasma cholinesterase were analysed in 193 apparently healthy volunteers (122 males, 71 females) with no known occupational exposure to cholinesterase inhibitors. Multiple regression analysis and analysis of variance showed statistically significant effects on the individual plasma cholinesterase activity by body weight, height, sex, and ChE-1 phenotype (but not by age or electrophoretic phenotype). Varying body weight explained one-fourth of the observed biological variance (s2total). The intra-individual variations during an 8-month period varied substantially from one individual to another (3% to 41% of the subject's mean activity); a repeated-measures analysis of variance showed a within-person variance (s2intra) = 5% of s2total. Intra-individual variation was uninfluenced by the variables that influence the inter-individual variance. A model for a 'standardized' plasma cholinesterase in which the combined effects of the four significant variables, ChE-1 phenotype, sex, body weight, and height are eliminated, is proposed for comparisons of plasma cholinesterase activities in unmatched population groups, e.g. within environmental or occupational medicine.

Adult↗
PubMed1989

[Amylase-producing lung tumors].

Raised serum amylase associated with pulmonary tumours is a rare phenomenon. On the basis of two cases, the literature is reviewed and the case histories are compared. The majority of tumours associated with raised serum amylase are adenocarcinomata and, in all of the cases in which determinations of isoenzymes were undertaken, the amylase-isoenzyme was of salivary gland type. In one of the authors' cases, immunhistochemical investigation revealed that the tumour cells contained amylase. In cases of hyperamylasaemia of unknown origin with increased amylase of salivary gland type, adenocarcinoma in the lungs should be considered as a possible diagnosis.

Adenocarcinoma↗
PubMed1989

[Initial results of high-dose-rate afterloading treatment of tumors in the head and neck region].

First results of high-dose-rate afterloading therapy in the head-neck area are encouraging. The procedure is not very invasive and is suitable especially for older patients, not tolerating much, who can be hardly submitted another therapeutic method. The limited spatial dose distribution allows a careful treatment of the surrounding tissue in spite of the application of high single doses, however limits the size of tumors too, that the afterloading therapy is possible in (max. 2 cm). The method represents an alternative of the much more complicated procedure of the low-dose contact therapy, that affects the patients in a stronger way like interstitial therapy and moulage treatment. No tumor recurrences or metastasis were seen in our patients. Influence of alteration in fractionation rhythm and of application of sources with very high dose capacity will be the subject of further studies.

Aged↗
PubMed1989

Additional electrophoretic components of cholinesterase in plasma: a phenomenon of no importance to the total plasma cholinesterase activity.

Total plasma cholinesterase and cholinesterase isozyme components were studied in 193 healthy subjects without occupational exposure to known cholinesterase inhibitors. The study showed that the four additional isozyme components, C5, C1', C6, and C7 occurred in plasma independently of each other, and that the total plasma cholinesterase activity was completely uninfluenced by the presence of any of the four components.

Adult↗
PubMed1988

Tissue activities of enzymes of diagnostic interest in the marmoset and rat.

The activities of enzymes of diagnostic interest were investigated in the liver, heart, kidney and muscle of the marmoset (Callithrix jacchus) and the rat. Methods of tissue extraction which gave maximal enzyme activity were used and comparison between the species showed some major differences. AST, LDH and GDH showed a similar distribution in both species but ICDH activity was much higher in the rat heart than in any other rat or marmoset organ. ALP, LAP and GGT were present in much higher activities in the rat kidney than in the marmoset kidney, a finding which was reversed in the liver of these animals. The major ALT-containing organ in the rat was the liver but, in the marmoset, this enzyme was found in relatively large quantities in the heart and muscle also. These differences can be of importance when plasma enzyme activities are measured following tissue damage.

Alanine Transaminase↗
PubMed1988

Amylase activity and fast-migrating amylase isoenzymes in serum and cyst fluid from patients with ovarian neoplasms.

160 patients with various ovarian tumors were studied to establish whether total amylase activity and the occurrence of fast migrating amylase isoenzymes in serum could serve as indicators of ovarian cancer. It was found that patients with benign and malignant ovarian tumors could not be classified by means of total amylase activity. Electrophoretic separation of the amylases revealed fast-migrating forms in serum from 10 of 47 patients with malignant ovarian neoplasms; 8 of these 10, and altogether 19 of the 47 patients had a serous cystadenocarcinoma. Two of the 109 patients with benign ovarian tumors also showed the pattern with fast-migrating amylases; both of them had a serous cystadenoma. Four patients with borderline tumors showed normal amylase patterns. Tumor origin of these fast-migrating amylase forms in serum was substantiated by 1) amylase reactive cells detectable in tumor tissue, and 2) surgical removal of tumor followed by complete disappearance of the fast-migrating amylase forms in serum. Normal serum amylase patterns do not exclude the presence of a malignant ovarian tumor, but occurrence of these abnormal amylase forms in serum may indicate that an ovarian tumor is a cystadenocarcinoma.

Amylases↗
PubMed1988

Plasma cholinesterase genetic variants phenotyped using a Cobas-Fara centrifugal analyser.

A two-step colorimetric method that overcomes the difficulties of the classic 240 nm benzoylcholine assay for plasma cholinesterase has been adapted to a Cobas-Fara centrifugal analyser, using choline oxidase coupled with peroxidase/phenol/aminoantipyrine for detection of the choline produced. Reaction conditions of the main reaction are identical to those of the classical benzoylcholine assay. The described method was applied to 105 selected serum samples, previously classified by the Danish Cholinesterase Research Unit as homo- or heterozygous for the usual (U), atypical (A), fluoride-resistant (F), or silent (S) allelic variants. The method showed a distinct separation of the various phenotypes, with catalytic activity concentrations, dibucaine numbers, and fluoride numbers directly comparable to established reference values of the manual 240 nm benzoylcholine method.

Butyrylcholinesterase↗