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Biomedical subjects

C Davies

Publications and source records attributed to C Davies.

At least 199 records · Page 11Linked to original sources
PubMed1980

Simultaneous analysis of disopyramide and quinidine in plasma by high-performance liquid chromatography.

A new reversed-phase high-performance liquid chromatographic method allowing simultaneous measurement of plasma concentrations of disopyramide and quinidine is described. Disopyramide and quinidine were separated on a reversed-phase column using 0.05 M phosphate buffer (pH 3.0)--acetonitrile (73:27, v/v), as mobile phase and the peaks were monitored by UV absorbance at the wavelengths of 254 and 325 nm. The drugs were extracted from alkaline plasma with chloroform containing the internal standard. The organic phase was evaporated to dryness and the residue was redissolved in a small volume of the mobile phase before analysis by high-performance liquid chromatography. The method is convenient and reliable in routine monitoring of both drugs.

Chromatography, High Pressure Liquid↗
PubMed1980

Phasic vagal influence on inspiratory motor output in anesthetized human subjects.

Vagal influence on inspiratory motor output was assessed in 20 normal subjects and in 12 patients with respiratory disorders under enflurane anethesia using the method of airway occlusion. The change in inspiratory duration during occlusion (delta TI) was measured from mechanical parameters (respiratory flow and tracheal pressure). In eight of the subjects, however, the effect of occlusion and augmentation of tidal volume was further evaluated from diaphragmatic electromyogram. In normal subjects delta TI (mechanical) averaged 0.15 s (range -0.1 to +0.77 s) and correlated with the duration of inspiration during occlusion. Electromyographic observations indicated that the change in neural TI exceeds the change in mechanical TI by approximately 0.2 s and that augmentation of tidal volume shortens TI with no apparent volume threshold. There was a tendency for vagal influence to be higher with restrictive lung disease and lower with obstructive airway disease. These observations indicate that a majority of humans display a significant vagal influence on TI in the spontaneous tidal volume range under anesthesia.

Aged↗
PubMed1979

Attempts to immunize rats against infection with Fasciola hepatica using in vitro culture antigens from newly excysted metacercariae.

Attempts were made to immunise rats against Fasciola hepatica using the culture products obtained from the in vitro cultivation of newly excysted metacercariae. Three culture regimes were chosen: (1) medium NCTC 135 for 48 h (2) NCTC 135 + 20 per cent fetal calf serum (FCS) for 48 h (3) NCTC 135 + 20 per cent FCS for 14 days. The used culture medium from each of these regimes was concentrated, mixed with adjuvant and injected subcutaneously into rats. Similarly treated unused culture media was used in control rats. The rats were challenged with an oral dose of 20 F hepatica metacercariae 35 days later and autopsied 96 days after the start of the experiment. The fluke burdens in those rats which had received the culture antigens did not differ significantly from those in the control groups.

Animals↗
PubMed1978

Ultrastructural immunocytochemical localization of two hydatid fluid antigens (antigen 5 and antigen B) in the brood capsules and protoscoleces of ovine and equine Echinococcus granulosus and E. multilocularis.

The unlabelled antibody method was used in the ultrastructural localization of two hydatid fluid antigens, antigen 5 and antigen B, in brood capsules and protoscoleces of Echinococcus granulosus and E. multilocularis. Antigen 5 was found in the parenchyma cells of the protoscolex and brood capsule wall and to a lesser extent in the walls of the flame cells and collecting ducts of the excretory system and in the surrounding interstitial material. It is suggested that, while some excretion of this antigen may occur from the protoscolex, it could also be liberated into the cystic cavity by degeneration of protoscoleces and parenchymal cells of the brood capsule wall. Antigen B was found mainly in the distal cytoplasm and perinuclear cytoplasm of the tegument anterior to the suckers. It is apparently secreted to the outside and was present in the brood capsule contents; it adheres to the anterior surface and the posterior periodic acid-Schiff (PAS)-positive glycocalyx of the protoscolex and to the inner surface of the brood capsule wall. The protoscolex tegument posterior to the suckers was negative. The parenchyma cells of the protoscolex and brood capsule wall were also positive although the intensity of the reaction product was variable.

Animals↗
PubMed1977

Immunohistological localisation of two hydatid antigens (antigen 5 and antigen b) in the cyst wall, brood capsules and protoscoleces of Echinococcus granulosus (ovine and equine) and E. multilocularis using immunoperoxidase methods.

Cyst wall, brood capsules and evaginated protoscoleces of E. granulosus (ovine and equine) and E. multilocularis were fixed in 10% formol-saline, embedded in paraffin and cut at 8 micrometer. Specific rabbit antisera to antigen 5 and antigen B of hydatid cyst fluid were used with immunoperoxidase methods to localise the antigens in the histological sections. Antigen 5 was found in all parasites and was associated with cells of the subtegumental area of the protoscolex, the brood capsule wall and the germinal membrane. The labelled antigen appeared as distinct granules in all areas. It is suggested that antigen 5 may be synthesised in all of these sites and that a source of the antigen in cyst fluid may be the germinal and brood capsule membranes. The laminated membranes of E. granulosus (ovine and equine) were, except for the superficial layers, free from antigen 5. Antigen B was present in all parasites. It was distributed diffusely throughout the laminated membrane, germinal membrane and brood capsule wall. There were areas of densely labelled antigen B on the surface of the distal cytoplasm of the protoscolex tegument and the surface of calcareous corpuscles. The distribution of antigen B in relation to PAS positive material and possible complement activating substances is discussed. The laminated membrane of E. granulosus was apparently more permeable to antigen B than to antigen 5. It is suggested that differences in the diffusion of these antigens through the laminated membranes of hydatid cysts in the same or different host species may account for variable serological responses during infection.

Animals↗
PubMed1976

Urate production in heterozygotes for glucose-6-phosphatase deficiency.

Urate production and excretion were studied in heterozygous parents of a child with glucose-6-phosphatase deficiency. Both parents demonstrated glucose-6-phosphatase concentrations in platelets intermediate between those in the homozygote and the normal. The miscible urate pool and turnover rate, the rate of incorporation of [14C]glycine into urate, the renal clearance of urate and the percentage excretion of labelled urate by the renal route were within the normal range in both heterozygotes, as were the serum cholesterol and triglyceride concentrations. Thus, a partial deficiency of glucose-6-phosphatase was not associated with the abnormalities of urate or lipoprotein metabolism which are features of homozygous glucose-6-phosphatase deficiency. Erythrocyte phosphoribosyl-pyrophosphate concentration, an increased concentration of which has been postulated as the mechanism responsible for the increased de novo purine biosynthesis in glucose-6-phosphatase deficiency, was found to be within the normal range in erythrocytes from both a homozygote and a heterozygote for this condition.

Adult↗