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Biomedical subjects

L D Hall

Publications and source records attributed to L D Hall.

142 records · Page 8Linked to original sources
PubMed1976

A general survey of the proton spin-lattice relaxation-times of some oligo- and poly-saccharide derivatives.

A Fourier-transform method has been used to measure the spin-lattice relaxation-times (T1 values) of the anomeric protons of a selection of oligo- and poly-saccharide derivatives. Although systematic variations are found for the substances of lower molecular weight, these variations are essentially non-existent at higher molecular weights. Data for the disaccharides cellobiose, maltose, lactose, gentiobiose, and melibiose demonstrate that proton T1-values may provide a powerful method for evaluating conformations of oligosaccharides.

Electron Spin Resonance Spectroscopy↗
PubMed1975

Deoxyfluoroketohexoses: 4-deoxy-4-fluoro-D-sorbose and -tagatose and 5-deoxy-5-fluoro-L-sorbose.

4-Deoxy-4-fluoro-alpha-D-sorbose (6) was prepared in crystalline form by the action of potassium hydrogen fluoride on 3,4-anhydro-1,2-O-isopropylidene-beta-D-psicopyranose (3) followed by deacetonation. Under identical conditions, 3,4-anhydro-1,2-O-isopropylidene-beta-D-tagatopyranose (7) underwent epoxide migration to give 4,5-anhydro-1,2-O-isopropylidene-beta-D-fructopyranose (12), which after deacetonation yielded 4-deoxy-4-fluoro-D-tagatose (15) and 5-deoxy-5-fluoro-alpha-L-sorbopyranose (16), the latter as the crystalline, free sugar. The action of glycol-cleavage reagents on the isopropylidene acetals of the deoxyfluoro sugars was consistent with the assigned structures. The structures were established by 13-C n.m.r. studies of the free deoxyfluoro sugars 6 and 16 and of the isopropylidene acetal 13, and by 1-H n.m.r. studies on the acetylated isopropylidene acetals 5 diacetate, 13 diacetate, and 14 diacetate. 5-Deoxy-5-fluoro-L-sorbose (16) was biologically active, producing in mice effects characteristic of deoxyfluorotrioses and of fluoroacetate. 4-Deoxy-4-fluoro-D-tagatose (15) and 4-deoxy-4-fluoro-D-sorbose (6) produced no apparent effects in mice up to a dose of 500mg/kg. The implications of these findings with respect to transport, phosphorylation, and the action of aldolase on ketohexoses are discussed.

Antineoplastic Agents↗
PubMedDate not supplied

Comparison of pH measurements made using 31P NMR and a fibreoptic pH meter.

The objective of this study was to compare pH measurements made in biological samples using 31P NMR (pHNMR) with those made with a novel, dye-based fibreoptic pH measurement system (pHF), which is compatible with use in electromagnetic fields without field perturbation. Using protein-free model solutions, pHNMR was calibrated against pHF, giving a correlation coefficient of 0.969 and a mean difference (+/- SD) between pHNMR and pHF of 0.037 +/- 0.054 over the pH range 6.8-7.7. Further calibration of pHNMR with pHF was carried out for human red blood lysates and then pHNMR was compared with pHF for whole, packed red blood cells over the pH range 7.0-7.8. Values for pHNMR, the intracellular pH, were consistently lower than for pHF, the extracellular pH, by a mean (+/- SD) of 0.15 +/- 0.02 units. A close correlation of extracellular pHNMR with pHF was demonstrated for a blood sample exhibiting two P(i) peaks, over the pH range 7.03-7.71. We conclude that concurrent use of NMR and the fibreoptic pH meter provides a reliable method of simultaneous measurement of intracellular and extracellular pH in biological systems.

Calibration↗
PubMedDate not supplied

Interventional treatment of hepatic arterial and venous pathology: a commentary.

Hepatic aneurysms, pseudoaneurysms and fistulas (arterial biliary and arterial portal) causing bleeding or portal hypertension, and arteriovenous malformations causing high output cardiac failure in adults can be successfully managed by embolization techniques. Results of embolization in infantile hemangioendotheliomas are less uniform and tumors with massive arteriovenous shunting are difficult to manage. Transjugular intrahepatic portal systemic shunts using expendable stents have been successfully created in patients and have effectively controlled portal hypertension and variceal bleeding.

Aneurysm↗
PubMedDate not supplied

Gianturco-Rösch expandable Z-stents in the treatment of superior vena cava syndrome.

Gianturco-Rösch expandable Z-stents were used in 22 patients with superior vena cava syndrome (SVCS). Stents were placed in all patients in the SVC and in 17 patients, also into the innominate veins. Stent placement resulted in complete relief of symptoms in all patients. Twenty-one patients had no SVCS recurrence from 1 to 16 months, to their death, or to the present time. SVCS recurred only in 1 patient 9 months after stent placement due to tumor ingrowth and secondary thrombosis. Based on ours and on other reported experiences, expandable metallic stents are effective devices for treatment of the SVCS which is difficult to manage by other means.

Brachiocephalic Veins↗
PubMedDate not supplied

Measurement of textural changes of food by MRI relaxometry.

This article summarises the current status of, and future prospects for, the use of magnetic resonance imaging (MRI) to evaluate the texture of a range of foods, and changes therein which accompany pathogen infection, natural ageing, damage, ripening and processing. The basic concept is that the magnetic resonance parameters of water are sufficiently sensitive to the texture of the food matrix, that magnetic resonance images of the spatial distribution of those parameters are effectively maps of the structural status of the foodstuff. This is illustrated in the context of the effects of pathogen infection in cucumbers, internal necrosis of melons, bruising in peaches, ripening of pineapples, and the effect of freeze-thawing on meat and fish.

Animals↗
PubMedDate not supplied

MR imaging using a rampable system.

A series of cranial images obtained at three magnetic field strengths in a volunteer on a fast ramp magnetic resonance system is presented. This study was undertaken in the space of 5 h.

Brain↗
PubMedDate not supplied

Ex vivo magnetic resonance imaging of the distal row of equine carpal bones: assessment of bone sclerosis and cartilage damage.

The distal row of carpal bones (C2, C3, and C4) from eight left intercarpal joints--four from Standardbred Trotters and four from Swedish Warmblood horses--were used to assess the potential of magnetic resonance (MR) imaging to detect cartilage and bone lesions. The joints used in the study were classified by macroscopic and radiographic examinations as having normal, mild, moderate, or severe articular cartilage lesions and bone sclerosis. Those classifications correlated well with the appearance of the MR images. Bone sclerosis in the MR images was observed as regions of decreased signal intensity. Upon quantitative analysis of the MR images there was a significant difference (p < 0.0001) in the MR signal intensity from areas where radiographic bone sclerosis was observed compared to areas of radiographic nonsclerotic bone. In addition, the MR images were used to pilot the location of histology slices through areas of interest that were then examined microscopically; hence, the lesions found from the MR imaging examination were verified microscopically. It was concluded that cartilage lesions and cartilage loss are related to the sclerotic state of the underlying bone. The MR protocols developed in this study were applied on five intact cadaveric carpal joints, and it was concluded that MR imaging could successfully be used in the intact joint to detect minor cartilage and bone lesions not visualized by either radiography or macroscopic examination. Hence, MR imaging can be used to delineate interactions between articular cartilage and subchondral bone over time and in vivo.

Animals↗
PubMedDate not supplied

Considerations for the programming of an open-loop insulin infusion device from the biostator glucose controller.

To assess the feasibility of preprogramming an open-loop device with insulin flow rates generated by the Biostator Glucose Controller, comparisons were made in 10 juvenile-onset diabetic patients between meals of equal size and composition taken in the morning, at noon, and in the evening and a bedtime snack during a 24-h period of Biostator glucose control. Four additional diabetic patients had Biostator glucose control for 72 h. Similar amounts of insulin were infused for the meals taken at differing times of the day and, except for the morning meal, for the same meal on two successive days. The meal-related glycemic patterns expressed as mean indices of meal excursions (MIME) were similar for meals of identical size and composition during a single day and for the same meal taken on two consecutive days. Preliminary results using an open-loop device preprogrammed by the Biostator system, although encouraging, underscore the deficiency of the subcutaneous route viz. the delayed entry of insulin into the circulation in achieving normal glucose levels and patterns.

Adult↗