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Biomedical subjects

D M Matthews

Publications and source records attributed to D M Matthews.

155 records · Page 9Linked to original sources
PubMed1965

Reversible absorptive defects in anticonvulsant megaloblastic anaemia.

Two cases of anticonvulsant megaloblastic anaemia are described, showing features of unusual interest. Though both cases were apparently deficient in folic acid, the Figlu tests were negative. One patient had an extremely low serum B(12) concentration apparently associated with defective B(12) absorption due to deficiency of intrinsic factor, and both showed impaired intestinal absorption of D-xylose. There was, however, no evidence of permanent gastro-intestinal dysfunction, and the absorptive defects disappeared completely after treatment with folic acid. Possible reasons for the findings are discussed. It is suggested that absorptive defects produced by the drugs may play some part in initiating anticonvulsant megaloblastic anaemia, and that once deficiencies of haemopoietic factors are established, a vicious circle may be set up owing to the effects of these deficiencies on the gastro-intestinal tract.

Adult↗
PubMed1965

Alpha-amino nitrogen in cerebrospinal fluid and its alterations in meningitis, multiple sclerosis, and some other neurological disorders.

The concentration of alpha-amino nitrogen (a measure of total amino-acids) was estimated in 58 samples of cerebrospinal fluid in which other findings were normal. Values for lumbar and ventricular cerebrospinal fluid in adults, and lumbar cerebrospinal fluid in children, are reported. A relationship was found between the concentrations of alpha-amino nitrogen in lumbar cerebrospinal fluid and in plasma.Alpha-amino nitrogen was also estimated in 79 samples of fluid from patients with meningitis, cerebral tumour, multiple sclerosis, and other neurological disorders. High concentrations were found in meningitis, spinal block, and xanthochromic fluids. In cerebral tumours, the concentrations were mostly normal. Low concentrations were found in children, in many cases of multiple sclerosis, and in benign intracranial hypertension. In some cases, the changes cannot yet be explained.

Amino Acids↗
PubMedDate not supplied

Absorption of di- and tripeptides by the intestine of the guinea-pig.

This paper describes a method of quantifying the amount of smaller peptides in physiological fluids and reports the preliminary results of studying the mesenteric blood of adult guinea-pigs during absorption of a partial hydrolysate of casein. Because of the different roles suggested for plasma and erythrocytes in the inter-organ transport of amino acids, both plasma and whole blood have been studied. Whole blood and plasma samples were deproteinized with sulphosalicylic acid, and amino acids and small peptides separated from residual small amounts of protein on a Sephadex G-25 column. Ion exchange chromatography was then performed before and after acid hydrolysis. The concentration of small peptides in blood seems to be much lower than was previously believed. The adult guinea-pig did not absorb small peptides across the intestine into mesenteric whole blood or plasma in our experiments. However, casein hydrolysates are not necessarily representative of all protein hydrolysates, and further studies are required using different proteins and varying degrees of hydrolysis. The possibility of peptide transfer during development, and in conditions involving mucosal damage, should also be investigated. The present investigation confirms the assumption that predominantly plasma, and not red blood corpuscles, carries amino acids from the gut to the liver. It is worth noting, however, that taurine, aspartic acid, glutamic acid, citrulline and arginine were found in higher concentrations in whole mesenteric blood than in plasma.

Amino Acids↗
PubMedDate not supplied

Effects of low cobalamin diet and chronic cyanide toxicity in baboons.

The effects of a low cobalamin (Cbl) diet, together with chronic cyanide or thiocyanate administration in some animals have been investigated in baboons over a period of 42 months. All animals remained healthy throughout the study and gained weight at a similar rate. None became anaemic or showed major haematological changes and there were no major neurological changes. Plasma total Cbl in the animals on the low Cbl diet fell within 9 months to values below the lower limit in man and were lowest at 24 months in baboons not receiving cyanide or thiocyanate. A striking feature in all animals, however, was an apparently seasonal increase in the plasma total Cbl each autumn with a corresponding decrease the following spring. This fluctuation was detected by radioisotopic assay but not by Euglena. Methylmalonic (MMA) excretion after oral valine ranged from 0.1--8.4 mg/24 h and was greatest in animals on the low Cbl diet and not receiving cyanide or thiocyanate. The results suggested an inverse relationship between MMA excretion and plasma total Cbl. Plasma thiocyanate was consistently higher in animals receiving cyanide or thiocyanate and at the end of the study plasma cyanide was highest in animals on the low Cbl diet receiving cyanide. The results support the suggestions that cyanide affects bodily handling of Cbl and that hydroxo-cobalamin plays a part in detoxication of cyanide.

Animals↗
PubMedDate not supplied

Use of a peptide rather than free amino acid nitrogen source in chemically defined "elemental" diets.

Previous studies have shown that amino acid (AA) residues are absorbed more rapidly from di- tripeptides than from free AA. In the present study, an intestinal perfusion technique has been used in normal human subjects to compare absorption of AA residues and total alpha-amino nitrogen (N) from 4 partial enzymic hydrolysates of protein (50--80% of the N contents present as small peptides) and their respective equimolar free AA mixtures. alpha-Amino N absorption was greater from 2 casein hydrolytes and a lactalbumin hydrolysate than from the respective free AA mixtures but similar to that from a fish protein hydrolysate and its AA mixture. The considerable variation in absorption of individual AA residues from the AA mixtures was much reduced when the protein hydrolysates were perfused, as a number of AA which were poorly absorbed from the AA mixtures were absorbed to a greater extent from the protein hydrolysates. The casein and lactalbumin hydrolysates had a stimulatory effect on jejunal absorption of water and electrolytes. In contrast, the fish protein hydrolysate appeared to cause a mean net secretion of fluid and electrolytes. The findings indicate that when absorption is limited by diminished luminal hydrolysis or absorptive capacity, serious consideration might be given to using partial enzymic hydrolysates of whole protein rather than free AA mixtures as the N source in "elemental" diets. Care should be taken, however, in ensuring that the preparation of choice does not promote a net secretion of fluid and electrolytes for such a property could have a deleterious effect in the clinical setting.

Adult↗
PubMedDate not supplied

Comparison of intravenous glucagon and dextrose in treatment of severe hypoglycemia in an accident and emergency department.

Hypoglycemia is a serious problem in insulin-treated diabetic patients. In this study the efficacy of intravenous glucagon (1 mg) was compared with that of intravenous dextrose (25 g) in the treatment of hypoglycemia in insulin-treated patients attending an accident and emergency department. In addition, the prevailing glycemic control of these patients was compared with patients routinely attending a diabetic outpatient clinic. Both intravenous glucagon and dextrose were effective in the treatment of hypoglycemic coma. There was a difference in the glycemic profile after intravenous glucagon compared with intravenous dextrose, and recovery of a normal level of consciousness after glucagon was slower than after dextrose (6.5 vs. 4.0 min, respectively; P less than .001), although the average duration of hypoglycemic coma was 1.4 h. The glucagon- and dextrose-treated groups had significantly lower HbA1 than comparable patients routinely attending the clinic (9.5 +/- 0.8 vs. 12.0 +/- 3.8%, respectively; P less than .001). In view of the ease of administration and the small risk of vascular and extravascular complications, intravenous glucagon appears to be a useful alternative to intravenous dextrose in the treatment of severe hypoglycemia.

Blood Glucose↗
PubMedDate not supplied

Effects of sorbinil treatment on erythrocytes and platelets of persons with diabetes.

Thirty-three diabetic subjects were given the aldose reductase inhibitor sorbinil (Pfizer, UK) for 3 wk. There was a significant fall in mean erythrocyte sorbitol concentration over this period. In all subjects erythrocyte sorbitol concentrations after treatment were within or below the range found in normal subjects. No changes in erythrocyte 2,3-diphosphoglycerate (2,3-DPG) or myo-inositol concentrations, plasma beta-thromboglobulin (beta-TG) concentration, or P50--a measure of the oxygen affinity of hemoglobin--were observed. There was a high incidence of adverse reactions to the drug.

Adult↗