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M D Bain

Publications and source records attributed to M D Bain.

27 records · Page 2Linked to original sources
PubMed1991

Enzymologic studies on patients with methylmalonic aciduria: basis for a clinical trial of deoxyadenosylcobalamin in a hydroxocobalamin-unresponsive patient.

Eleven patients with methylmalonic aciduria have been classified on the basis of detailed enzymology on cultured skin fibroblasts. Nine were classified as mutase deficiencies and were unresponsive to hydroxocobalamin in vivo or in vitro. One was classified as a Cbl A variant and was responsive to hydroxocobalamin therapy in vitro and in vivo. Patient 11 was classified as having deoxyadenosyltransferase deficiency (Cbl B). However, a clinical therapeutic trial of deoxyadenosylcobalamin resulted in no clinical or biochemical improvement. Further studies on the patient's cultured fibroblasts suggested that deoxyadenosylcobalamin fails to reach the mitochondria in an intact form. These studies show that detailed enzymologic classification is essential for the reliable evaluation of the response to therapeutic maneuvers; complementation studies alone may be inadequate to completely classify these patients. Therapy with deoxyadenosylcobalamin offers no advantages over the use of hydroxocobalamin in the treatment of patients with methylmalonic aciduria.

Alkyl and Aryl Transferases↗
PubMed1990

Dietary treatment eliminates succinylacetone from the urine of a patient with tyrosinaemia type 1.

Over an 18-month period serial observations of plasma tyrosine, methionine and urinary tyrosine metabolites were made and compared with urinary succinylacetone excretion in an infant with tyrosinaemia type 1 treated by diet alone. Despite broadly similar profiles there were significant temporal and quantitative differences between each of these metabolic parameters. Only when plasma tyrosine was kept in the low-normal range by strict phenylalanine restriction (10-15 mg phenylalanine/kg body weight) was detectable succinylacetone consistently eliminated from the urine. Urinary succinylacetone is the only measure of metabolite accumulation immediately proximal to the enzyme defect and its routine measurement will allow more effective control of dietary treatment.

Amino Acid Metabolism, Inborn Errors↗
PubMed1990

Permeability of the human placenta in vivo to four non-metabolized hydrophilic molecules.

1. Permeability of the human placenta to four permeants of different molecular size was measured at Caesarean section in seven normal full-term pregnancies. 2. Placental clearance for mannitol was 8.7 +/- 1.1 ml min-1 (mean +/- S.E.M.), lactulose 6.3 +/- 0.8, chromium ethylenediaminetetraacetic acid (CrEDTA) 3.7 +/- 0.5, and inulin 0.98 +/- 0.1. 3. The permeability data were analysed in terms of restricted diffusion through 'notional' water-filled pores and found to be incompatible with a single population of uniform pores.

Adult↗
PubMed1988

Contribution of gut bacterial metabolism to human metabolic disease.

Metronidazole, an antibiotic with specific activity against anaerobic bacteria, was of clinical and biochemical benefit in two patients with methylmalonic aciduria. The virtual elimination of propionic acid from the stool suggested that propionic acid derived from faecal bacterial metabolism contributes substantially to methylmalonate production. These findings point to a novel avenue of treatment for these disorders of intermediary metabolism, and indicate the importance of microbial gut flora in normal human metabolism.

Bacteria, Anaerobic↗
PubMed1988

In vivo permeability of the human placenta to inulin and mannitol.

1. Permeability of the term human placenta to inulin and mannitol was measured in six normal pregnancies. 2. Bolus and continuous infusion of inulin and mannitol to the mother for 1-2 h before delivery by Caesarean section achieved steady-state maternal serum concentrations. Net accumulation of inulin and mannitol in the fetus was measured by the subsequent neonatal urinary excretion. 3. Transplacental clearance was calculated by dividing the net flux by the time-averaged transplacental concentration gradient. Clearance for inulin was 0.86 +/- 0.1 ml min-1 (mean +/- S.E.M.) and for mannitol 7.3 +/- 0.8 ml min-1 (n = 6 in both cases).

Female↗
PubMed1986

Robinow syndrome without mesomelic 'brachymelia': a report of five cases.

A family is described in which the father and his two children had Robinow syndrome, but with no consistent brachymelia or dwarfism. Two further sporadic cases are described, one with rhizomelic brachymelia and dwarfism and the other with generalised shortening of the limbs. An attempt is also made to distinguish between the phenotype of autosomal dominant and recessive cases on the basis of the familial cases in this paper and other reported cases.

Abnormalities, Multiple↗
PubMedDate not supplied

Fever-range hyperthermia stimulates alpha4beta7 integrin-dependent lymphocyte-endothelial adhesion.

Migration of blood-borne lymphocytes into lymphoid tissues is initiated by the L-selectin and alpha4beta7 integrin adhesion molecules. Previous studies have shown that L-selectin adhesion is dynamically regulated by febrile temperatures. It is now reported that fever-range hyperthermia also acts directly on lymphocytes to enhance selected adhesive functions of alpha4beta7 integrin. Fever-range hyperthermia treatment in vitro (40 degrees C, 12 h) of murine TK1 lymphoma cells and human peripheral blood lymphocytes (PBL) stimulates alpha4beta7 integrin-dependent adhesion to high endothelial venules (HEV) in Peyer's patch and mesenteric lymph node frozen sections. TK1 cells are alpha4beta7hi L-selectin(lo), allowing for the analysis of alpha4beta7 integrin without contributions from L-selectin. Adhesion was further shown to involve alpha4beta7 integrin and its endothelial counter-receptor, mucosal addressin cell adhesion molecule-1 (MAdCAM-1) using function-blocking antibodies (i.e. DATK32, HP2/1, MECA-367). Fever-range hyperthermia also promotes alpha4beta7 integrin-mediated aggregation of TK1 cells. In sharp contrast, hyperthermia fails to increase alpha4beta7 integrin adhesion to fibronectin by TK1 cells. Expression of the alpha4beta7 heterodimer on TK1 cells or human PBL is not altered by hyperthermia, suggesting that hyperthermia stimulates adhesion by enhancing alpha4beta7 integrin avidity rather than its cell surface density. These results provide a mechanism whereby febrile temperatures during infection or clinical hyperthermia potentially amplify the immune response by stimulating L-selectin and alpha4beta7 integrin-dependent homing of immune effector cells to lymphoid tissues.

Animals↗
PubMedDate not supplied

Cytokine and adhesion molecule expression in primary human endothelial cells stimulated with fever-range hyperthermia.

Migration of blood-borne lymphocytes into lymphoid tissues and sites of inflammation is initiated by vascular adhesion molecules and proinflammatory cytokines. Previous in vivo studies have shown that febrile temperatures dynamically stimulate adhesion in differentiated high endothelial venules (HEV), which are portals for lymphocyte extravasation. This report examines the direct effect of fever-range hyperthermia on the expression of adhesion molecules and cytokines by primary cultured endothelial cells. In both macrovascular (HUVEC) and microvascular (HMVEC) endothelial cells, fever-range hyperthermia (40 degrees C for 6-12 h) did not affect expression of adhesion molecules (ICAM-1, E-selectin, VCAM-1, P-selectin, PECAM-1, PNAd, MAdCAM-1), cytokine release (IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-11, IL-12, IL-13), or chemokine secretion (IL-8, RANTES, MCP-1, MIP-1beta, MIG). This is in contrast to the stimulatory effects of TNF-alpha or 43 degrees C heat shock. However, a novel role for fever-range hyperthermia was identified in augmenting actin polymerization in cultured endothelial cells and enhancing the ability of endothelial-derived factors to transactivate the alpha4beta7 integrin lymphocyte homing receptor. These findings provide insight into the tightly regulated effects of fever-range hyperthermia that exclude induction of adhesion in non-activated endothelium of normal blood vessels. Through these mechanisms, it is proposed that febrile temperatures associated with infection or clinical hyperthermia avoid the unproductive exodus of lymphocytes to non-involved extralymphoid tissues while simultaneously promoting lymphocyte delivery to sites of immune activation.

Actins↗