Search PubMed⌕ Search

Biomedical subjects

B J Martin

Publications and source records attributed to B J Martin.

At least 181 records · Page 10Linked to original sources
PubMed1974

Human placental cathepsin B1. Isolation and some physical properties.

A reproducible procedure for the isolation, from human placenta, of a cathepsin B1 in a homogeneous state, demonstrated by electrophoretic, ultracentrifugal and enzymic criteria, was carried out. The pH optimum was near pH5.5. The placental enzyme catalysed the release of acid-soluble u.v.-dense products from haemoglobin and myoglobin. It was inhibited by heavy metals and several compounds which react with the thiol groups. The optimum temperature was between 37 degrees and 42 degrees C. The molecular weight of the enzyme was calculated to be 24250.

Cathepsins↗
PubMed1972

The variable prevalence of junctional-complex-associated bodies in the human sweat gland.

Sweat gland biopsies have been examined for their content of junctional-complex-associated (JCA) bodies. These bodies have been observed at the lumen of the gland as well as the intercellular canaliculi. A JCA body was encountered in each of two dark cells with uncondensed secretory granules; one of these cells was from a specimen in which no other bodies could be found after an extensive search. All other JCA bodies occurred in either clear or undifferentiated cells. Junctional-complex-associated bodies occupied pairs of adjacent cells rather frequently, but no cell revealed more than one body. The prevalence of JCA bodies varied widely among specimens. Glands lacking morphologic abnormalities, and others with some atypical features, disclosed few or no such bodies. Some glands that contained JCA bodies also contained coil cells with extensive vacuolization, which occurred as a manifestation of Hurler's disease or on an unexplained basis. Glands from a patient with cystic fibrosis exhibited the highest prevalence of JCA bodies. Some of the coil profiles in glands near a scar in one specimen were composed of undifferentiated cells with rare mitotic figures and no identifiable clear or dark cells. Numerous JCA bodies, particularly at the lumen, were found in sweat glands in this and another specimen containing frequent undifferentiated cells.

Biopsy↗
PubMedDate not supplied

Effect of adenosine deaminase inhibition with pentostatin on myocardial stunning in dogs.

Pentostatin (2-deoxycoformycin) is a potent inhibitor of adenosine deaminase and has been demonstrated to augment endogenous adenosine levels during regional and global myocardial ischemia. Based on the rationale that increasing endogenous adenosine during ischemia may be cardioprotective, the objective of this study was to determine if adenosine deaminase inhibition with pentostatin could improve postischemic contractile dysfunction (stunning) in open-chest anesthetized dogs. All animals underwent 15 min of coronary occlusion followed by 3 h of reperfusion preceded by an intravenous bolus of either 0.2 mg/kg of pentostatin (n = 8) or saline (n = 7). Sonomicrometers were placed in the ischemic area and were used to measure systolic wall thickening before, during, and after occlusion of the left anterior descending artery. Myocardial blood flow was measured with tracer labeled microspheres at baseline, 10 min of occlusion and at 1 h of reperfusion. Both groups were equally dyskinetic during occlusion (-21 +/- 5% of baseline thickening in the controls and -28 +/- 8% in the pentostatin group). The pentostatin group, however, demonstrated better contractile function at all time points during reperfusion, which was significantly different from the control group at 3 h of reperfusion. The improvement in regional function in the pentostatin group was not due to significant disparities in hemodynamic variables, size of the region at risk, or in collateral blood flow. These results indicate that pentostatin can ameliorate the severity of myocardial stunning, an effect we propose is due to increasing endogenous levels of adenosine during the ischemic interval. Although significant improvement was detected with pentostatin, the improvement was modest compared to controls, suggesting that the utility of inhibiting adenosine deaminase to modify regional mechanical stunning is limited.

Adenosine Deaminase Inhibitors↗
PubMedDate not supplied

The effects of keyswitch stiffness on typing force, finger electromyography, and subjective discomfort.

The effects of keyswitch stiffness and key action on typing force, electromyography (EMG), and subjective preference were examined. Each subject's own keyboard (with an audible key click and key activation force of 0.72 N) and three keyboards with no key click that were identical in design but had different key activation forces (0.28 N, 0.56 N, and 0.83 N) were used. Subjects (24 female transcriptionists) typed on each keyboard for 15 min while typing force and left hand surface EMG of the finger flexor and extensor muscles were monitored. Subjects then used one of the keyboards at their workstations for 7 workdays and were monitored again. This procedure was repeated for all four keyboards. Typing force and finger flexor and extensor EMG activity were highest for the 0.83 N keyboard. Lowest EMG values were for the 0.28 N and the 0.72 N audible key click keyboards. Baseline (10th percentile) and median (50th percentile) extensor EMG values were significantly higher than flexor EMG values. Peak (90th percentile) EMG values were comparable for flexors and extensors. Mean subjective discomfort was significantly higher for the 0.83 N keyboard at the fingers (36% higher), lower arm (40% higher), and overall (39% higher). Seventeen of 24 subjects preferred the 0.72 N keyboard, 4 the 0.28 N keyboard, and 3 preferred the 0.56 N keyboard. Results suggest that increasing make force causes typing force and EMG to increase but that the ratio of 90th centile typing force to make force decreases as make force increases. Subjective discomfort was significantly higher for the keyboard with 0.83 N make force. Buckling spring keyboards have better feedback characteristics, which may be responsible for a decrease in the amount of typing force and EMG produced.

Adult↗
PubMedDate not supplied

Analysis of a marine fish cell line from a male sheepshead.

Chromosomes from consecutive culture passages of a developing cell line from fin fibroblasts of a male sheepshead (Archosargus probatocephalus) were analyzed. It was demonstrated that the modal chromosome number is 48. The chromosome types found in these cells included 8 submetacentrics, 8-12 acrocentrics, and 28-32 telocentrics. Evidence suggests that the primary type of chromosomal alteration that occurred in cultured SHF-1 cells is aneuploidy; a large metacentric chromosome of undetermined origin was observed.

Aneuploidy↗
PubMedDate not supplied

Mesenchymal stem cells: stealth and suppression.

Human post-natal bone marrow contains mesenchymal stem cells (MSCs), which are capable of giving rise to multiple mesenchymal cell lineages. Large quantities of human MSCs can be readily obtained following a simple bone marrow aspiration procedure and subsequent expansion over a million-fold in culture. This extensive capacity for clinical scale expansion in vitro has facilitated the development of preclinical models as well as clinical studies designed to assess the safety, feasibility, and efficacy of transplanting allogeneic MSCs for a variety of indications. This review focuses on the rationale for performing clinical studies of MSC transplantation and will discuss the potential role that MSCs may have in the field of hematopoietic stem cell transplantation as well as for the repair or regeneration of bone, cartilage, and cardiac tissues.

Animals↗