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Biomedical subjects

C J Martin

Publications and source records attributed to C J Martin.

At least 127 records · Page 7Linked to original sources
PubMed1986

Lung tissue tension and glycosaminoglycans.

This study tested the hypothesis that the loss of tissue tension which occurs when lung parenchyma is immersed in phosphate buffered saline (PBS) follows a loss of glycosaminoglycans (GAG) and/or protein. Tissue tension decay (TTD) was examined in 30 X 30 X 100 micron strips of rat lung parenchyma immersed in PBS in the presence of agents altering the loss of GAG. GAG were labeled with [35S]sulfate in vitro by tissue culture of lung explants and in vivo by intraperitoneal injection of [35S]sulfate. Labeled GAG were lost from lung explants, lung homogenates, and whole lung immersed in saline. The rate of GAG loss was found to correlate with early TTD. In the presence of agents that markedly reduced the leach rate of GAG from lung parenchyma (Safranin O, Alcian Blue, Acridine Orange) there was no TTD. Cetyl-pyridinium chloride was also effective. Polybrene, however, caused a significantly greater TTD than seen in saline with some reduction in the total amount of GAG leached from the tissue. Greater amounts of heparin sulfate were lost in the presence of polybrene. Human serum, dextran-70, ovalbumin, and gelatin significantly reduced but did not prevent TTD. Dextran-70 was effective in reducing the loss of GAG from tissue explants. Agents that reduced disulfide bonds (dithiothreitol, 2-mercaptoethanol) markedly increased TTD and increased the loss of GAG and protein from lung explants and lung homogenates. These studies provide further evidence that lung tissue tension is a function of the interstitial matrix interacting with the connective tissue network. When the GAG and protein responsible for the swelling pressure of matrix are preserved the tissue tension is stable for one hour or more. Agents that partially preserve the matrix are somewhat effective in reducing TTD while those that increase the loss of GAG and protein increase the loss of tension. From the differential effect of agents that retard and accelerate GAG, heparin sulfate (HS) may be the most important GAG to the tissue properties.

Animals↗
PubMed1986

Phytic acid-metal ion interactions. II. The effect of pH on Ca(II) binding.

The interaction of phytic acid with Ca(II) has been studied by potentiometric titration and by measurement of free Ca(II) concentrations using an ion Selective electrode. With increasing Ca(II) concentration, the titration curve of phytic acid is displaced to regions of lower pH. In the binding of calcium ions to phytic acid, there is no evidence that significant binding occurs below approximately pH 5. Above this pH, the extent of binding is dependent upon both pH and the calcium to phytic acid ratios. Maximum binding obtains at a Ca(II):phytate ratio of 6 with 4.8 mol of Ca(II) bound per mol of phytate above pH ca. 8. Binding constants are apparently very large since binding isotherms at any Ca(II):phytate ratio are a linear function of the total calcium ion concentration. In all cases, binding occurs only when one or more phosphate groups have been converted to the oxo dianion form. The apparent pK' values (curve-fit parameters) that describe the potentiometric titration data are in good agreement with the constants evaluated from the binding of Ca(II) to phytate as a function of pH. Using CPK space-filling models, structures containing six metal ions in coordinate linkage to pairs of oxo dianions have been constructed and discussed within the framework of the axial conformation of phytic acid and the order of proton removal with an increase in pH based upon NMR studies.

Calcium↗
PubMed1986

Prostaglandin E2 but not I2 restores furosemide response in indomethacin-treated rats.

Indomethacin attenuates furosemide's natriuretic response. Although this has been attributed to cyclooxygenase inhibition, attempts to correlate prostaglandin (PG) production with furosemide's natriuresis have led some investigators to conclude that prostaglandins are not involved in this response. This study was designed to evaluate the effects of intraaortic administration of PGE2, PGI2 (100 ng X kg-1 X min-1), or the vasodilators secretin or bradykinin (75 microU X kg-1 X min-1) on the furosemide-indomethacin antagonism. Fractional sodium excretion (FENa) during furosemide administration was 4.59 +/- 0.50% in control rats but 1.84 +/- 0.33% in indomethacin-treated rats (Indo) (P less than 0.001). PGE2 prevented indomethacin from attenuating furosemide's response (FENa, 3.91 +/- 0.25%; P = NS vs. control; P less than 0.01 vs. Indo). PGI2, however, failed to prevent the furosemide-indomethacin antagonism (FeNa, 1.94 +/- 0.59%, P less than 0.001 vs. control; P = NS vs. Indo). Inulin clearance, arterial pressure, filtered sodium load, and renal blood flow were not different between groups. Neither secretin nor bradykinin prevented the indomethacin-furosemide antagonism. This study is consistent with the hypothesis that indomethacin antagonizes furosemide's natriuretic response by prostaglandin synthesis inhibition. Furthermore, PGE2 seems to restore furosemide's response through actions other than a vasodilatory effect.

Animals↗
PubMed1985

A role for interstitial matrix in tissue tension of alveolar wall.

Single alveolar walls subjected to length-tension studies in saline and Bicine (0.2 M) undergo a progressive decay in tissue tension (TTD). We have examined the effect of different solutions on this TTD and looked for corresponding changes in the ultrastructure. Lung parenchyma was dissected to single alveolar walls (30 X 30 X 150 microns) in phosphate-buffered saline (0.15 M). Transferred to a length-tension bath, the tissue was immersed in Bicine, saline, fortified Hank's solution, 0.25% Alcian blue in saline, or a sodium dodecyl sulfate solution, for variable periods. Cycled through a given extension with peak force measured over time, these same tissues were fixed in buffered glutaraldehyde/tannic acid and processed for electron microscopy. Single alveolar walls immersed in saline or Bicine showed a progressive TTD. Vacuoles or spaces appeared in the interstitium which with cellular disorganization progressed with the TTD. Seen within 0.3 h, the changes were well advanced at 0.6 h. In sodium dodecyl sulfate (70 mM), however, there was no TTD and structurally there was no interstitium, with only basement membranes and fibrous proteins remaining. In fortified Hank's solution or 0.25% Alcian blue the interstitial matrix, cell morphology and tissue tension were well preserved for 1 h. This study suggest that leaching of the interstitial matrix occurs in saline or Bicine, and an intact matrix is essential for the preservation of tissue tension.

Alcian Blue↗
PubMed1985

Exposure treatment of the burned patient--a computer simulation of the thermal environment and its effect on evaporation and heat loss.

The influence of the thermal environment on evaporation and heat loss from burned tissue has been studied in order to optimise conditions for treatment of severely burned patients. Diffusion resistances have been defined to describe movement of water vapour through the skin and away from the body surface. These have been evaluated from experiments on a water phantom and from data on evaporation rates from burned tissue and normal skin. Results show that the diffusion resistance for burned tissue is less than one tenth of that for normal skin, but changes substantially during the development of an eschar. Evaporation is promoted by a high skin temperature and a low relative humidity, but not by raising the ambient air temperature. Blowing warm dry air over a burn wound will enhance evaporation and reduce heat loss, encouraging the rapid formation of a dry eschar to provide a barrier against infection. Selective irradiation of burned tissue with low levels of radiant energy can be used to compensate for local heat losses, and allow the air temperature in the treatment room to be kept at a level comfortable for the patient and nursing staff.

Body Temperature Regulation↗
PubMed1983

Use of computer analysis of echocardiograms for assessment of left ventricular function.

Computer analysis of M-mode echocardiograms has been used for evaluation of left ventricular function. Ventricular dimensions and velocities of heart wall movement have been measured. In addition, a non-invasive estimate of ventricular wall stress has been obtained using the systolic cuff blood pressure combined with echocardiogram data, and simultaneous apex cardiography has been employed to look for any disruption in the timing of changes in ventricular dimension and wall stress. Various parameters have been calculated from the data to provide a quantitative indication of changes in the ventricle. A study has been carried out of 117 patients divided into four groups; one of normal subjects and the others containing patients with ischaemic heart disease, hypertrophic cardiomyopathy and dilated cardiomyopathy. Abnormal features of the echocardiograms have been evaluated from comparisons with data for normal subjects. Relationships between the quantities measured have been studied to give a fuller understanding of changes taking place in the ventricle, so that the data can be employed as the basis for a non-invasive assessment of ventricular function.

Adult↗
PubMed1982

Assessment of left ventricular function by synchronous echocardiography and apex cardiography.

The relationship between left ventricular dimension measured using M-mode echocardiography and simultaneous apex cardiography has been studied in 69 normal subjects (2 groups) and 159 patients with heart disease (6 groups). A loop was formed by plotting the apex cardiogram, which is related to ventricular wall stress, against ventricular dimension. Abnormalities in ventricular function due to shape or volume changes in the isovolumic phases of the cardiac cycle produced characteristic alterations in the loop pattern. These changes were measured and the results for different groups compared. Normal subjects were divided into two age groups (13-38, 40-78) and no significant differences were found between them. In the heart-disease, patients, 25% had an abnormal decrease in dimension during isovolumic contraction and 25% had an abnormal increase during isovolumic relaxation. When the downstroke of the apex cardiogram was differentially analysed, it was possible to show that 60% of heart-disease patients lay outside the normal range. By using these techniques it is possible (a) to show abnormal ventricular response to pressure changes during the isovolumic periods, (b) to quantify the abnormality and, (c) to detect early abnormal muscle behaviour before it becomes visible on conventional ultrasound recordings.

Adolescent↗
PubMed1982

A study of ultrasound-induced microstreaming in blood vessels of tropical fish.

Tails of the tropical fish Xiphophorous maculatus have been studied by light microscopy during irradiation with continuous wave 780 kHz ultrasound. Acoustically-induced microstreaming was observed in blood vessels during irradiation with peak intensities above 1 Wcm-2. The microstreaming took the form of rotation of single blood cells and clusters of a few cells and occurred at positions close to the edges of cartilage rods supporting the tail. Streaming was detected initially in vessels 5-10 micrometers across where it impeded blood flow, and as the blood velocity fell it was also observed in larger vessels 15-30 micrometers across. Measurements of rotation speed showed that streaming velocity increased with intensity. The microstreaming is thought to result from radiation torque created by the complex standing wave field produced by reflection from the irradiation tank window and the cartilage rods, or by vibration of the rods in the sound field.

Animals↗
PubMed1981

Solitary rectal ulcer syndrome in Northern Ireland. 1971-1980.

Fifty-one cases of solitary rectal ulcer syndrome diagnosed over the past 10 years have been studied. The syndrome, of which solitary ulceration was a feature in only 35 per cent of cases, included patients with multiple 'solitary' ulcers (22 per cent), broad-based polypoid lesions (25 per cent) and patchy granular hyperaemic rectal mucosa (18 per cent). The syndrome was found to be strongly associated with abnormal rectal descent. Full-thickness prolapse to or beyond the anal verge was present in 59 per cent of patients while a further 32 per cent had lesser degrees of rectal descent. In only 9 per cent was no such abnormality demonstrated. Treatment with high roughage diet supplemented with bulking agents benefited two-thirds of 27 patients so treated. Ivalon sponge rectopexy has been performed in 6 patients with associated complete rectal prolapse, and in the first 3 of these (followed for a sufficient period) the results have been satisfactory.

Adolescent↗