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Biomedical subjects

B J Martin

Publications and source records attributed to B J Martin.

At least 73 records · Page 4Linked to original sources
PubMed1993

Endothelium in the aorta and ilio-femoral arteries proximal to femoral arteriovenous fistulae in rabbits.

The endothelium and underlying internal elastic lamina of the aorta and ilio-femoral arteries from 15 rabbits with femoral arteriovenous fistulae (2 to 92 days postoperatively) and 3 rabbits with control femoral arteriotomies were examined using the en face technique and scanning electron microscopy. The rapidity of development of the tears in the internal elastic lamina of the muscular ilio-femoral arteries was greater than in fistulae involving the elastic common carotid artery. The elastic tissue tears appeared to have a predilection for certain anatomical regions possibly related to regions of specific hemodynamic stress. A few tears were observed in the aorta near the origin of the renal arteries. Initially the elastic tissue tears in the afferent ilio-femoral arteries were longitudinally orientated and the endothelium overlying the elastic tissue tears soon exhibited increased cell density relatively restricted to the floor of the tears. This cellular pattern was similar to that in the carotid-jugular fistulae. With time the endothelium assumed a more conventional morphology.

Animals↗
PubMed1993

Ultrastructural alterations of collagen fibrils in blood vessel walls.

With increasing concern for elucidation of the role of connective tissues in degenerative diseases of blood vessels, an ultrastructural study was conducted on collagen fibrils of intimal proliferation in experimental autogenous venous pouch aneurysms in rabbits and in atherosclerotic human arteries. The fibrils were compared morphometrically with adventitial collagen as controls. In intimal proliferation from both species intimal collagen fibrils displayed increased variation in shape and size when compared to adventitial collagen fibrils. The abnormal fibrils resembled those of inherited connective tissue diseases, indicating that the changes in collagen fibrils can be acquired and that hemodynamic stress is likely to contribute to their occurrence.

Aged↗
PubMed1993

A new biomechanical approach to assessing the fragility of the internal elastic lamina of the arterial wall.

Patterns of tearing of the internal elastic lamina induced by controlled tensile extension of the arterial wall in the axial direction are similar morphologically to those induced in vivo in the anastomosed arteries of experimental arteriovenous fistulae. The mural response is modelled with a simple bi-layer analogue and it is shown that the internal elastic lamina exhibits a greater degree of strain-limiting deformation behavior in the axial direction than the medial and adventitial layers. Application of laminate theory indicates that the frequency of intimal tearing along the vessel length is directly related to the failure strength of the intimal layer.

Animals↗
PubMed1993

Contribution of the tonic vibration reflex to muscle stress and muscle fatigue.

The aim of the investigation was to determine the influence of vibration displacement amplitude (200, 300 microns peak-to-peak), as opposed to acceleration effects at selected frequencies (40, 80, 100, 120, 150, 200 Hz), on a commonly observed but often undesired motor response elicited by local vibratory stimulation, that is, the tonic vibration reflex (TVR). Vibration was applied to the distal tendons of the hand flexor muscles. Changes in the activity of hand flexor and extensor muscles were analyzed as a function of both their initial contraction level (0, 10, 20% of maximal voluntary contraction) and the vibration parameters. The main results indicate that TVR increases with the initial muscle contraction and increases with vibration frequency up to 100-150 Hz but decreases beyond. High-frequency vibration seems to induce less muscle and tendon stress. This result is particularly important for the design of handheld vibrating tools.

Adult↗
PubMed1993

Changes in collagen fibril morphology in experimental aneurysms and arteriovenous fistulae in sheep.

To investigate the effect of haemodynamic stress on collagen fibril morphology, the ultrastructure of intimal and adventitial collagen in the walls of experimental saccular aneurysms and in the veins of arteriovenous fistulae in sheep was compared with that of adventitial collagen from control veins. Ultrastructurally the collagen fibril is usually described as having a regular round profile in cross-section and a diameter dependent on collagen function and location in the blood vessel wall. The collagen fibrils in the intimal proliferation from both experimental models showed increased variation in shape and size when compared with adventitial collagen. These abnormally shaped collagen fibrils resemble those seen in inherited connective tissue disorders and in blood vessels from aged animals, suggesting that the collagen changes can be acquired and can be produced experimentally in blood vessels subjected to augmented haemodynamic stress.

Aneurysm↗
PubMed1993

A busy urban geriatric day hospital: analysis of one year's activity.

Lightburn Geriatric Day Hospital is a 30-place unit sited adjacent to Geriatric Assessment and Rehabilitation wards and three miles from the local district general hospital in east Glasgow. The service serves an urban population of 25,000 persons aged 65 or more. During 1991 a data capture form was used to prospectively record Day Hospital referral patterns and activity. There were 731 new patient referrals, accounting for a total of 5,780 patient attendances. Thirty-eight per cent of new patients attended without prior screening (unscreened General Practitioner (GP) referrals). Booked occupancy was 85.5%, actual occupancy 76%. The average period of attendance was three weeks (median number of attendances: 7) and 18% of attenders required in-patient care. Specific after-care arrangements were made for 85% of patients on discharge from day hospital. Low rates for re-attendance (within three months of day hospital discharge) and chronic attendance (more than three months) as well as favourable responses from surveys of both GPs and patients suggest effective use of the Day Hospital resource, but more direct measures of Day Hospital effectiveness are required.

Aged↗
PubMed1993

Chronic physical activity alters hepatobiliary excretory function in rats.

Recent studies have indicated that exercise causes alterations in the biotransformation of some xenobiotics and the clearances of antipyrine and [14C]aminopyrine. The present study has investigated whether chronic voluntary physical activity alters hepatobiliary excretory function by comparing the clearance and biliary excretion of model substrates for each of four carrier-mediated transport systems (anion, uncharged, bile acid and cation; n = 8 for each chemical in each group) in active and inactive female rats. The active rats had access to running wheels and voluntarily ran 11.2 +/- 0.68 km/day. The active rats were fed ad libitum, and ate 37% more food than weight-matched, restricted-fed sedentary control rats. Basal bile flow was 34% higher in active rats than in inactive rats, and excretion of bile acids, cholesterol and phospholipid were also increased. The biliary excretion and biliary clearance of the anion, indocyanine green, were elevated in active rats, although total clearance and serum concentrations were not different due to decreased non-biliary clearance. Serum elimination and total clearance of the uncharged substrate, ouabain, were elevated in the active rats, due entirely to increased nonbiliary clearance. Total clearance of the bile acid, taurocholate, was higher in active rats due to an increased biliary clearance. In contrast, there were no differences in either the biliary excretion or clearances of the cation, procainamide ethobromide, between the two groups of rats. Finally, no differences in volume of distribution or elimination half-life were noted between inactive and active rats for any of the substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyrine↗
PubMed1992

Chronic physical activity: hepatic hypertrophy and increased total biotransformation enzyme activity.

Does chronic voluntary physical activity alter hepatic or intestinal capacities for xenobiotic biotransformation? This question was investigated by comparing biotransformation enzyme activities in liver and small intestine of active and sedentary rats. Male rats allowed unlimited access to a running wheel and fed ad lib. for 6 weeks were weight-matched to sedentary controls; the active rats ate 22% more food than the sedentary rats (P less than 0.05). Active rats ran 2.8 +/- 0.6 miles/day. Liver weights were higher in the active rats (11.2 +/- 0.2 vs 9.8 +/- 0.2 g; P less than 0.05), as were total liver protein, and liver microsomal and cytosolic protein (P less than 0.05). As a result of liver hypertrophy, the active rats showed higher total liver activity of several biotransformation enzymes, including 2-naphthol sulfotransferase, styrene oxide hydrolase, benzphetamine N-demethylase, ethacrynic acid glutathione S-transferase and morphine UDP-glucuronosyltransferase (P less than 0.05). In contrast, there was no detectable difference in total liver N-acetyltransferase activity toward p-aminobenzoic acid, 2-naphthylamine, and 2-amino-fluorene as well as, relative hepatic enzyme activity (expressed per g liver or per mg protein) and total and relative intestinal enzyme activity. We conclude that chronic voluntary physical activity, accompanied by an increased food intake, results in liver hypertrophy and potentially increases total hepatic capacity to biotransform certain xenobiotic chemicals.

Animals↗
PubMed1992

Isolation and purification of extracellular matrix vesicles from blood vessels.

Extracellular membrane-bound vesicles (called matrix vesicles) which occur in abundance in atherosclerotic blood vessels are believed to be associated with lipid accumulation and calcification. A technique has been developed to isolate them from experimental aneurysms in sheep in which they are known to be plentiful. The matrix vesicles were isolated by differential centrifugation following extraction by hypotonic salt solution. Most of the vesicles were pelleted at 30,000g and fell within the size range of matrix vesicles in situ in the aneurysmal wall. Preliminary characterization of the enzymatic activities indicates that many of these vesicles are formed from cell membranes rather than being derived from lysosomes, mitochondria or endoplasmic reticulum. Morphologically they are similar to matrix vesicles of other mineralizing tissues.

Animals↗
PubMed1992

Elderly patients and their medication: a post-discharge follow-up study.

Fifty-six elderly patients (age range 65-98 years) discharged from a geriatric unit were visited at home on or after the 5th post-discharge day (median day 8) and their medication assessed. By the day of the visit, 15 of the 56 had not had a new prescription issued (27%) and 27 patients (48%) had old prescribed medication at home. Forty-one new scripts, issued by general practitioners, should have contained 128 medications if the general practitioners wished to continue unchanged the medication given on hospital discharge. Fourteen drugs (11%) had been added and 17 drugs (13%) omitted. The number of prescriptions issued unchanged was 26/41 (63%). Inaccurately labelled containers and/or changed drug names were found in 28%. Contrary to hospital advice, 47% of medications were issued in childproof containers. Poor communication between hospital and general practitioners is only part of the problem. Methods to expedite the delivery of new prescriptions should be developed.

Aged↗
PubMed1992

Coordination of deglutition and phases of respiration: effect of aging, tachypnea, bolus volume, and chronic obstructive pulmonary disease.

The effects of aging, tachypnea, bolus volume, and chronic obstructive pulmonary disease on the coordination of swallowing with the phases of respiration were studied by concurrent respirography and submental surface electromyography. Study findings showed that in young healthy volunteers, during rest, there is preferential coupling of subconscious swallowing with the expiratory phase of continuous respiration. This preferential coupling of swallowing with expiration was found to increase relative to other phases of respiration during water swallows and tachypnea (P < 0.05). Respiratory phase occurrence of swallowing and postdeglutitive resumption of respiration during exacerbation of chronic obstructive pulmonary disease was found to be significantly different compared with the basal state (P < 0.05). Respiratory phase occurrence of subconscious swallowing in the elderly was found to be different from the young (P < 0.05). Position had no significant effect on the coordination of swallowing and phases of respiration. We concluded that in resting young volunteers the majority of deglutitions are coupled with the expiratory phase of swallowing. This coupling is increased in frequency by the presence of a liquid bolus and tachypnea. And finally, age and chronic obstructive pulmonary disease alter this coordination significantly.

Adult↗
PubMed1992

Staff selection for an ambulatory surgery unit.

Major changes in the care delivery system affect the selection of the professional nursing staff for an ambulatory surgery unit. The skills required are diverse and dynamic. Selecting the right applicant requires not only knowledge of the interview process, but also acute observation and communication skills. The use of a matrix system helps to organize the process as well as to quantify and qualify the information gained.

Ambulatory Surgical Procedures↗
PubMed1992

Endothelium and elastic tears in the afferent arteries of experimental arteriovenous fistulae in rabbits.

The endothelium and underlying internal elastic lamina of the arteries from 16 carotid-jugular arteriovenous fistulae in rabbits were examined using the en face technique and scanning electron microscopy respectively. Tears appeared in the internal elastic lamina of the arteries 3 days post-operatively. The overlying endothelium exhibited cytoplasmic pallor, loss of argyrophilia of cell borders, and at times attenuated endothelial cells bridging thrombus covered regions of denudation. Early endothelial lesions repaired rapidly and were found only 3-7 days post-operatively despite progressive increase in frequency and extent of tears and the development of interconnecting longitudinal tears with time. Following repair endothelial cells over the tears were small with hyperchromatic nuclei and oriented mostly parallel to the arterial axis. Endothelial cell density overlying these elastic tissue tears increase to three times that in contralateral arteriotomized common carotid arteries. These endothelial changes were sharply delineated by the margins of the elastic tears. Cell density over the tears reached its maximum 9-11 days post-operatively with mitotic figures both in the floor of the tears and over islands of residual elastic lamina. With time the cell density progressively diminished and endothelial cells assumed a more conventional elongated spindle shape.

Animals↗
PubMed1992

Smoking-induced changes in epithelial lining fluid volume, cell density and protein.

Bronchoalveolar lavage has proved a useful research technique for recovering cellular and molecular contents of the lower respiratory tract. Because the recovered fluid is variably diluted, an accurate estimation of molecular and cellular concentrations can only be made if the epithelial lining fluid volume recovered is also known. It has been suggested that smoking may alter epithelial lining fluid volume by reducing clearance or by stimulating production and, thus, affect the interpretation of bronchoalveolar lavage studies. In this study, urea was used as an endogenous marker of epithelial lining fluid volume in a comparison of 26 smokers and 31 nonsmokers. The mean epithelial lining fluid volume recovered from smokers was significantly greater than that of nonsmokers (2.4 +/- 1.40 ml vs 1.2 +/- 0.75 ml, p less than 0.005). The total cellular concentration in the bronchoalveolar lavage fluid in smokers was also greater (94.2 +/- 46 x 10(6) vs 33.9 +/- 21.5 x 10(6) cells per 300 ml lavage), even when corrected for bronchoalveolar lavage volume recovered (63.1 +/- 32.5 x 10(6) vs 24.9 +/- 13.3 x 10(6) cells per 100 ml recovered lavage fluid). This was true for macrophage, lymphocyte and neutrophil cell numbers. However, when corrected for the apparent epithelial lining fluid volume, only the macrophage count remained significantly higher in the smokers compared with nonsmokers (30.66 +/- 20.7 x 10(6) vs 18.21 +/- 8.6 x 10(6) macrophages.ml-1 ELF). In addition, concentrations of albumin and immunoglobulin M (IgM) were significantly lower in smokers after correction for epithelial lining fluid volume. These results highlight smoking as a confounding factor in the interpretation of bronchoalveolar lavage data.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchoalveolar Lavage Fluid↗