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Biomedical subjects

J A Knight

Publications and source records attributed to J A Knight.

At least 73 records · Page 4Linked to original sources
PubMed1985

In-vitro stability of human alpha-fetoprotein.

We assessed the stability of alpha-fetoprotein (AFP) in clinical specimens in the presence and absence of serum and albumin, at different temperatures and concentrations. We find it depends on both AFP concentration and incubation temperature. Dilution of most specimens with either phosphate buffer or phosphate-buffered saline or by immunoelectrodiffusion resulted in some loss of AFP. Attempts to stabilize AFP during either sample dilution or incubation by use of albumin in concentrations up to 1 g/L did not protect it from inactivation unless normal human serum was also included. Frozen AFP solutions were less stable than solutions stored at 4 degrees C. AFP was most stable when lyophilized and stored desiccated. The AFP-inactivation curves were usually nonlinear. Apparently both polymerization and degradation occur simultaneously as AFP loses its activity. Proteolytic enzyme inhibitor and sulfhydryl reagent not only failed to protect it from inactivation, they appeared to speed it.

Amniotic Fluid↗
PubMed1985

Pulmonary alveolar proteinosis in the newborn.

A newborn presented with respiratory distress syndrome that was felt to be both clinically and roentgenographically typical of hyaline membrane disease. At autopsy, the lungs were firm, dry, and bulky, and sections from all lobes revealed mucin-negative, periodic acid-Schiff-positive, diastase-resistant material typical of pulmonary alveolar proteinosis. Electron microscopy documented the lamellar structure of the intra-alveolar material. There was no clinical or autopsy evidence of immunodeficiency.

Age Factors↗
PubMed1985

Standard lecithin/sphingomyelin and phosphatidylglycerol techniques compared with immunologic slide test.

A commercially available, rapid, technically simple, immunologic slide agglutination test for amniotic fluid (AF) phosphatidylglycerol has been compared with the lecithin/sphingomyelin (L:S) ratio and phosphatidylglycerol determined by thin-layer chromatography. The immunologic test lacks sensitivity when compared with phosphatidylglycerol measured by thin-layer chromatography, and both phosphatidylglycerol measurements are considerably less sensitive than the L:S ratio. The authors' results suggest that the immunologic test is probably useful as a screening test, but all negative results should be immediately followed up with an L:S ratio and phosphatidylglycerol measured by thin-layer chromatography.

Agglutination Tests↗
PubMed1984

Sex determination of monomorphic birds by fibreoptic endoscopy.

Fibreoptic endoscopy was performed in 1056 monomorphic birds of 144 different species belonging to 15 Orders. The purpose was to establish their sex by direct inspection of the gonads. The results suggest that although the technique involves surgical intervention it is generally more practical and accurate than chromosome analysis of lymphocytes or analysis of faecal steroids. Surgical anaesthesia is recommended on practical and humane grounds but this and the technique itself can be hazardous in old and fat birds, where a mortality rate of as high as 2 per cent was encountered. Cloacal examination of as high as 2 per cent was encountered. Cloacal examination is a more practical technique for sex determination in penguins.

Animals↗
PubMed1984

Comparative studies of the use of some injectable anaesthetic agents in birds.

The effect of three injectable drugs and a combination of two of them was compared in birds. The agents were ketamine hydrochloride, xylazine hydrochloride and the steroid mixture alphaxalone-alphadolone. Ketamine and xylazine were used in combination. One hundred and fifty-four species, all maintained by major zoos in the United Kingdom, were involved in the study. The results indicate that the drugs used produced more widely differing effects in the range of species studied than have previously been reported.

Anesthesia↗
PubMed1983

Sexing penguins by cloacal examination.

Cloacal examination to determine sex was carried out in 145 penguins of five species. The birds were from four of the major collections in the British Isles. Differences in the appearance of the urodaeum were sufficient to differentiate between the sexes in the species examined.

Animals↗
PubMed1983

The chemical basis and specificity of the nitrosonaphthol reaction.

1-Nitroso-2-naphthol reacts with various 5-hydroxyindoles as well as para-substituted phenols and guaiacols. Consequently, this reaction has long been used to measure tyrosine in tyrosinosis and tyrosinemia, homovanillic acid in neuroblastoma, and 5-hydroxy-3-indoleacetic acid in the carcinoid tumor. We report here on the specificity of this reaction, as well as our early observations with respect to the chemical basis of the reaction.

Amino Acid Metabolism, Inborn Errors↗
PubMed1983

Interference with carcinoembryonic antigen radioimmunoassays by glycosaminoglycans, and their removal.

Using the reagents from the CEA-Roche kit, we found that solutions containing only glycosaminoglycans (GAG) yielded false concentrations of carcinoembryonic antigen (CEA), and mixtures of CEA and GAG produced falsely high values. On the other hand, solutions of GAG yielded no additional CEA concentration when reagents from the Abbott CEA kit were used; rather, the CEA result was decreased with the Abbott kit for a CEA solution also containing GAG. These effects of GAG were not ascribable to contamination, because neither gel filtration nor ion-exchange column chromatography separated the false Roche CEA content related to GAG from their peaks of uronic acid or from their anticoagulant activity. In addition, an enzyme specific for GAG eliminated these GAG-derived false concentrations. Both the positive and negative effects are correlated with concentrations of GAG. We found that the concentration of GAG could be decreased in a solution containing plasma proteins by either heating (70 degrees C, 15 min) or treating with perchloric acid (0.6 mol/L). The former is superior because essentially all GAG added to a solution containing plasma proteins were removed by heat, whereas as much as 25% to 80% of the GAG still remained after acid treatment. The effect of GAG was also completely eliminated by treating the specimens with chondroitinase ABC lyase (EC 4.2.2.4).

Carcinoembryonic Antigen↗
PubMed1982

Haematological findings in healthy and sick African grey parrots (Psittacus erithacus).

Full blood counts and fibrinogen estimations were carried out on 11 clinically normal, adult African grey parrots. Reference values derived from these tests were used to identify abnormalities in the blood counts of 11 sick parrots thought to be suffering from bacterial infections. All sick birds showed higher than normal heterophil counts, paralleled in some cases by lymphocytosis, monocytosis, thrombocytosis and increased fibrinogen levels. Anaemia was present in two birds and several others showed minor red cell abnormalities. The findings indicate that clinical haematology can make a useful contribution to the differential diagnosis of infection in African grey parrots. The findings also suggest that the development of anaemia can be a significant complicating factor in infectious conditions in these birds.

Animals↗
PubMed1981

gamma-Glutamyltransferase and alkaline phosphatase activities compared in serum of normal children and children with liver disease.

We compared alkaline phosphatase (EC 3.1.3.1) and gamma-glutamyltransferase (EC 2.3.2.2) activities in sera from children with various hepatic diseases with values for normal children. Although values for both enzymes are above normal in essentially the same liver disorders, the latter is much more specific and sensitive. A single value for alkaline phosphatase, measured at any time during childhood or at any stage of liver disease, is extremely difficult to interpret. We suggest that measurement of gamma-glutamyltransferase routinely replace alkaline phosphatase as a screening test and in following patients with obstructive or infiltrative hepatic disorders. We give reliable reference intervals for gamma-glutamyltransferase covering the entire pediatric age group.

Adolescent↗
PubMed1981

Early (chemical) diagnosis of bacterial meningitis--cerebrospinal fluid glucose, lactate, and lactate dehydrogenase compared.

Both lactate and lactate dehydrogenase are more sensitive as early indicators of bacterial meningitis than is glucose, and both appear to help differentiate aseptic from bacterial meningitis. In selected cases, lactate dehydrogenase may be more sensitive than lactate. We also give reference intervals for cerebrospinal fluid cell count, glucose, lactate, and lactate dehydrogenase.

Child↗