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Biomedical subjects

B J Martin

Publications and source records attributed to B J Martin.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Isocapnia blocks exercise-induced reductions in ocular tension.

Previous reports suggest that isometric exercise (2-min handgrip at 50% maximal voluntary contraction [MVC]) substantially lowers intraocular pressure (IOP). The authors questioned whether the mechanism for lowered IOP in exercise is secondary to hyperventilation. Accordingly, in this study 11 subjects, with elevated IOP (greater than or equal to 18 mm Hg) and otherwise healthy, did 2 min of handgrip exercise at 50% MVC with and without carbon dioxide supplementation to maintain isocapnic conditions. Compared with a control experiment that involved neither exercise nor CO2 addition, exercise induced a fall in IOP from 18.3 to 15.6 mm Hg (P less than 0.001). This statistically significant decline in IOP persisted for 15 min after the exercise session. At the point of minimum IOP (1 min after the end of exercise), the minute ventilation was elevated from 6.5-8.1 l/min (P less than 0.05), and the end-tidal partial pressure of CO2 (PCO2) was reduced from 37.0 to 33.7 mm Hg (P less than 0.05) with respect to control values. By contrast, adding CO2 sufficient to maintain isocapnic conditions (experimental end-tidal PCO2 = 38.9 versus 38.5 mm Hg in the control study; P = not significant) abolished the exercise-induced ocular hypotension (experimental IOP = 17.8 versus 18.1 mm Hg in the control study; P = not significant). It was concluded that prevention of hypocapnia during isometric handgrip exercise blocks the subsequent fall in IOP, suggesting both that isometric exercise per se has no direct influence on IOP and that therapy for ocular hypertension could involve manipulation of blood gases.

Adult↗
PubMed1991

Comparison of inorganic elements from autopsy tissue of young and elderly subjects.

Concentrations of nine inorganic elements in autopsy samples of kidney, liver, heart and skeletal muscle from 33 aged subjects, mean age 80 years, were compared with concentrations in similar samples from 12 young healthy accident victims, mean age 29 years. Tissue samples were removed within 48 hours of death and dry weight was used as a frame of reference. Potassium and magnesium were significantly lower in muscle (P less than 0.001) and heart tissue (P less than 0.001) of elderly subjects. There was evidence of accumulation of zinc in liver tissue of the elderly (P less than 0.01). Copper was significantly lower in the heart tissue of elderly subjects (P less than 0.001) whereas manganese was lower in both the heart (P less than 0.01) and the kidney tissue (P less than 0.001) of the elderly. Selenium concentrations were lower in the kidney (P less than 0.001) of the elderly. Elderly heart tissue appeared to accumulate chromium (P = 0.007) and aluminium (P less than 0.001). No significant differences were found for iron concentrations between these two populations. These major differences in tissue element concentrations between young and aged subjects merit further attention.

Age Factors↗
PubMed1991

The interaction of hand vibration with oculomanual coordination in pursuit tracking.

The effects of high frequency hand vibration (150 Hz) on simultaneous ocular and manual tracking performances were investigated in trained human subjects. First, a zero-order pursuit tracking task was performed with and without direct visual control of the hand. Second, eye tracking of an imaginary target linked to the hand was also performed. The results show that hand vibration significantly alters eye and hand tracking performances when the hand is out of sight. However, when the hand is placed in the visual field, tracking performances are less affected by vibration. Visual cues on limb segments may compensate to some extent for the vibration-induced alteration of proprioceptive information otherwise used to control movements. Eye movements are altered during vibration while the subject is tracking or fixating an imaginary target attached to the hand. These findings explicitly show that hand vibration can perturb oculo-manual coordination control. The present results imply that vibration-induced activity of somesthetic mechanoreceptors is likely to contribute to oculomanual coordination alteration and tracking decrement in vibratory environments. Furthermore, direct visual control of the hand and/or arm may be of particular interest in manipulation tasks executed under vibration.

Adult↗
PubMed1979

Cesarean hysterectomy: a twenty-five-year review.

This article analyzes cesarean hysterectomies performed at Louisville General Hospital on clinic patients for the 25 year period 1953 through 1977. During this time there were 63,259 deliveries, of which 2417 were cesarean sections and 149 were cesarean hysterectomies. Twenty-six of the latter were classified as emergency operations done for urgent medical indications; in the remaining 123 patients the indications were elective to some degree. Operative and postoperative complications and morbidity are discussed, and changing trends regarding the place of cesarean hysterectomy in obstetrics over the years are evaluated.

Adolescent↗
PubMed1979

CO2 and exercise tidal volume.

In progressive exercise increased tidal volume (VT) accompanies increased ventilation (VE) until a VT plateau is reached. We observed in 13 subjects a correspondence between the arrival of the VT plateau and the anaerobic threshold (AT). To examine this association between a mechanical event (the VT plateau) and a metabolic event (the AT), we changed those variables that change at the AT and looked for changes in VT. We found in 13 subjects that CO2 addition to prevent alveolar hypocapnia during cycle ergometer exercise progressing to exhaustion in 12-15 min significantly elevated the VT plateau (mean increase 4.4%; P less than 0.01) as compared with a spontaneous test that induced a mean end-tidal carbon dioxide tension fall of 5.5 Torr. This VT increase was mediated by a significant increase in inspiratory time (TI; P less than 0.02); both the ratio of TI to the total breath duration (TI/Ttot) and the mean rate of inspired airflow (VT/TI) were unchanged at matched VE. Changing other variables known to change at the AT--blood lactate ion concentration and alveolar oxygen tension--left ventilatory pattern unchanged. These results suggest that hypocapnia in severe exercise measurably lowers the VT plateau in normal man.

Carbon Dioxide↗
PubMed1979

Influence of exercise hyperthermia on exercise breathing pattern.

Passive elevation of the body core temperature (Tc) induces rapid, shallow breathing in resting man. We wondered if exercise-induced Tc elevation would also lead to decreased tidal volume (VT) and increased breathing frequency (f) during exercise. To investigate this question, 10 subjects each performed 47 min of cycle ergometer exercise at 50--60% of the maximal aerobic capacity, with the work rate adjusted to maintain ventilation (VE) constant. This long ride raised mean Tc (rectal) 0.8 degrees C. Before and immediately after the long ride, ranges of VE and VT were obtained from short 6-min rides that progressed from unloaded pedaling to the anaerobic threshold. At the constant VE of the long ride, f rose and VT fell as Tc rose (P less than 0.05). The fall in VT was associated with a fall in inspiratory time (TI); drive (VT/TI) and timing (TI/Ttot)components of VE were unchanged. These effects were consistent over the entire range of VE obtained from the short 6-min rides. Passive heating in warm water to produce equal Tc elevation in the same subjects yielded similar exercise breathing-pattern changes. These findings suggest that increased Tc mediates the VT fall during prolonged exercise, possibly through stimulation of the central respiratory pacemaker.

Body Temperature↗
PubMed1979

Low exercise ventilation in endurance athletes.

Previous studies have shown that endurance athletes are endowed with low ventilatory responses to chemical stimuli. The implications of this association have never been clear. Although recent evidence shows that exercise ventilation (VE) correlates with ventilatory chemoresponsiveness in a group of athletes, the extent to which non-athletes may differ from athletes in this regard is unknown. We have examined the relationship between ventilatory chemoresponsiveness and exercise VE in a group of 7 non-athletes, and contrasted these findings with those obtained previously from 8 endurance and 8 non-endurance athletes. Correlation lines of exercise VE with chemical responses were similar in slope and intercept for both athletes and non-athletes. However, we found that non-athletes had greater exercise VE per unit metabolic rate (VO2 or VCO2), and greater ventilatory responses to O2 and CO2, when compared with endurance athletes at equal relative work loads (P less than 0.05). The lower exercise VE/VCO2 of endurance athletes as compared with non-athletes persisted in hyperoxia, indicating that factors other than differences in hypoxic sensitivity explain the lower exercise VE of endurance athletes. Low exercise VE may be the link between low ventilatory chemosensitivity and outstanding endurance athletic performance.

Adult↗