Search PubMed⌕ Search

Biomedical subjects

G Cooper

Publications and source records attributed to G Cooper.

At least 181 records · Page 10Linked to original sources
PubMed1985

A community-centered alcoholism assessment/treatment service: a descriptive study.

This paper describes socio-demographic, alcohol-related, legal, medical, behavioural and treatment characteristics of 407 patients with problems of alcoholism/drug abuse assessed over a period of three years in a community oriented assessment and treatment program. The results show that patients entering this program represent a cross section of alcoholics in the area. These patients are similar to those entering traditional outpatient and residential facilities on most demographic variables; severity of alcoholism, length of history, and previous treatment experience. However, they are slightly younger and differ significantly from the others on their sources of referral. Over the three year period a significant change has occurred in the relationship between the program and the sources of referral. The implications of these findings for planning comprehensive treatment services for alcoholism are discussed.

Adolescent↗
PubMed1985

Day treatment for alcoholism in a general hospital psychiatric service.

In this paper a time limited, cost effective day treatment program for alcoholics, and characteristics of patients entering this treatment program, are described. The advantages of this day treatment program are discussed with special emphasis on its relationship with other community service agencies, with the community at large and, with a General Hospital Mental Health service, of which it is a part. The implications for planning cost effective treatment services for alcoholics are discussed.

Adult↗
PubMed1985

New approaches to the study of cellulose biosynthesis.

Examples of a variety of approaches for studying the mechanism and regulation of cellulose biosynthesis are presented. Attempts to demonstrate conclusively a cellulose synthase activity using membrane preparations derived from higher plants have not been successful; the predominant UDP-glucose: beta-glucan-beta-glucosyltransferase detected in these preparations is a beta-(1----3)-glucan synthase that is dependent upon Ca2+ and a beta-glucobiose, such as laminaribiose or cellobiose, for activity. Xyloglucan glucosyltransferase activity is detected in all plant preparations examined and, in cotton fibres, the activity of this enzyme correlates well with the level of xyloglucan found in the fibre. Low activity for a Mg2+-dependent beta-(1----4)-glucan synthase is found in extracts from soybeans and mung beans, but not cotton fibres; this enzyme could represent either a dissociated form of xyloglucan glucosyltransferase or a partially latent form of cellulose synthase. In vitro translation of RNA from developing cotton fibres shows notable increases in the level of several relatively abundant translatable mRNAs associated with the time of onset of secondary-wall cellulose synthesis. In order to determine whether these apparent changes in gene expression represent enhanced expression of specific genes required for cellulose synthesis, several strategies are being developed for identification of specific polypeptides required for this process. One strategy involves the successful development of a technique for detection of glucan synthase activity in acrylamide gels, a technique that should prove useful for characterization of the polypeptide composition of such enzymes. We have also synthesized a photoaffinity analogue of 2,6-dichlorobenzonitrile (DCB), a potent and specific inhibitor of cellulose synthesis. The analogue is also an effective inhibitor in vivo, and upon ultraviolet irradiation of extracts in the presence of the radioactive analogue, we observe a relatively specific labelling of a polypeptide of 18 X 10(3)Mr. Finally, we have studied the spatial regulation and structural requirements for cellulose synthesis in internode cells of the alga Chara corallina. Cellulose deposition in vivo shows spatial localization, which correlates with acid and base bands along the cell. Using internodes perfused with solutions containing UDP-[14C]glucose and subsequently ligated, we were able to demonstrate synthesis of a highly insoluble cell-wall-localized glucan, thus offering hope that Chara can be developed as another useful system for studying the mechanism and regulation of cellulose synthesis.

Cell Membrane↗
PubMed1984

Activity of multiple sclerosis during pregnancy and puerperium.

The influence of pregnancy on multiple sclerosis was studied in 338 women by determining in each trimester of pregnancy and post partum the number of relapses and the corresponding relapse rate. Eighty-five relapses occurred in association with 199 pregnancies, most (65) in the postpartum period, and a low number of relapses (2) were recorded in the last trimester of pregnancy. Comparing the average exacerbation rate of the study group with that of patients with multiple sclerosis in Israel (0.28 relapses per person per year), we found a statistically significant decrease in the third trimester (0.04) and a high increase in the first three months post partum (0.82). This pattern of remissions at the end of pregnancy and exacerbations post partum is similar to that observed in other putative autoimmune diseases.

Adult↗
PubMed1984

The assessment of changes in brain volume using combined linear measurements. A CT-scan study.

All linear measurements employed for evaluation of brain atrophy, were performed on 148 computed tomograms of patients aged 28 to 84 without evidence of any nervous system disorder. These included size of lateral, third and fourth ventricles, width of the Sylvian and frontal interhemispheric fissures and cortical sulci and size of the pre-pontine cistern. Various parameters indicated decrease in brain mass with age. Since the atrophic process is a diffuse phenomenon, integration of several measurements evaluating separate brain regions was made. The bicaudate ratio and the Sylvian fissure ratio (representing both central and cortical atrophy) were combined arithmetically, resulting in a correlation of 0.6390 with age (P less than 0.0005). With a computed canonical correlation analysis; a formula was obtained which combined measurements of the lateral and third ventricles, the Sylvian fissure and the pre-pontine cistern. This formula yielded a correlation of 0.67795 (P less than 0.0005). These linear measurements will allow simple and reliable assessement of reduction in brain volume during the normal aging process and in disorders accompanied by brain atrophy.

Adult↗
PubMed1984

Hypertrophy without contractile dysfunction after reversal of pressure overload in the cat.

To determine whether a causal relationship exists between the myocardial hypertrophy and the deficits in myosin ATPase activity and contractile function that have been associated with chronic, experimental pressure overload, we studied contractile function, myosin ATPase, and isomyosin pattern in a model of severe pressure overload in which the pressure overload was surgically relieved but hypertrophy persisted. Severe hypertrophy, contractile dysfunction, and pump failure were produced in the cat right ventricle by tight pulmonary arterial banding. In two groups of cats banded for 2- and 7-wk periods, right ventricular mass doubled, and contractile function was severely depressed compared with controls. In another group of cats subjected to severe right ventricular pressure overload for 4 wk, pressure overload was reversed by removal of the pulmonary arterial band. After a 4-wk recovery period for this group, right ventricular mass remained markedly increased, but contractile function had returned to normal. Changes in neither isomyosin composition nor myosin ATPase activity were found regardless of contractile function. Thus, following reversal of a right ventricular pressure overload severe enough to cause pump failure and a twofold increase in right ventricular mass, muscle contractile function can return to normal even when severe hypertrophy persists. Furthermore, changes in myosin isozyme composition or ATPase activity do not explain the changes in contractile function.

Adenosine Triphosphatases↗
PubMed1984

Complete reversibility of cat right ventricular chronic progressive pressure overload.

Chronic, progressive pressure overload of the cat right ventricle produces persistent, ongoing abnormalities of contractile, energetic, and biochemical function in vitro at a time when in vivo pump function is still normal. The present study tested the reversibility of the in vitro changes in this clinically relevant hypertrophy model. Fourteen sham-operated and 14 reversal cats were studied. After banding the animals as 1-kg kittens, right ventricular pressures were normal. Before band removal (25.2 +/- 0.5 weeks later for the control group and 25.5 +/- 0.3 weeks later for the hypertrophy reversal group), systolic right ventricular pressures were 24 +/- 1 mm Hg for controls and 71 +/- 5 mm Hg for the hypertrophy reversal group (P less than 0.05). At study, 19.5 +/- 1.1 weeks after a second sham operation for controls or 18.7 +/- 0.7 weeks after band removal for the hypertrophy reversal group, these pressures were 24 +/- 1 mm Hg for controls and 23 +/- 1 mm Hg for the hypertrophy reversal group (P = NS); cardiac output was 0.18 +/- 0.01 liters/kg per min for controls and 0.19 +/- 0.01 liters/kg per min for the hypertrophy reversal group (P = NS). The ratio of right ventricle to body weight was normal in both groups, as was the right ventricular papillary muscle myocyte cross-sectional area and the myocardial collagen concentration. A right ventricular papillary muscle from each cat was studied at 29 degrees C in a polarographic myograph. Preloaded shortening velocity was 0.79 +/- 0.04 muscle lengths/sec for controls and 0.86 +/- 0.03 muscle lengths/sec for the hypertrophy reversal group (P = NS); extent of shortening was 0.15 +/- 0.01 muscle lengths for controls and 0.16 +/- 0.01 muscle lengths for the hypertrophy reversal group (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Atrophy reversal and cardiocyte redifferentiation in reloaded cat myocardium.

We have recently described rapid cardiac atrophy in response to decreased load. The present study was designed to determine whether this atrophy is solely a degenerative response of damaged myocardium or is, instead, an adaptive response of viable myocardium. A discrete portion of cat myocardium was unloaded by severing the chordae tendinae of a single right ventricular papillary muscle. One week later, the muscle was reloaded by attachment of its apex to the ventricular free wall. This allowed the load to be removed and restored without altering the blood supply, innervation, or frequency of contraction of the tissue. In myocardium unloaded for 1 week, the cardiocyte cross-sectional area and the volume densities of mitochondria and myofibrils decreased significantly. Large areas of cytoplasm were devoid of organelles, and the few remaining myofilaments were oriented in a variety of directions rather than longitudinally within the cell. Upon reloading for 1 week, the cardiocyte cross-sectional area, volume density of mitochondria, and ultrastructural organization all returned to normal. The volume density of the myofibrils increased toward control, and they reoriented with respect to the long axis of the cardiocyte. The contractile function of the papillary muscles, which was depressed as early as 1 day after unloading and almost absent at times later than 3 days after unloading, returned to normal after 2 weeks of reloading. This study demonstrates that adult mammalian myocardium responds to unloading with a marked loss of cellular differentiation, organization, and function which is fully reversible with reloading. This plasticity in response to load may well be the basic mechanism responsible for the development and maintenance of normal cardiac structure and function.

Aging↗
PubMed1983

Early morphological alterations of pressure-overloaded cat right ventricular myocardium.

Pressure overload of the right ventricle results in an increase in ventricular mass. It also results in abnormal in vitro contractile function in advance of the onset of congestive heart failure as determined in papillary muscles removed from these ventricles. To correlate these functional abnormalities with any early underlying morphological changes, a band was placed around the proximal pulmonary artery of cats. This band restricted the lumen to 20% of normal and was left in place for 2 weeks. At that time, hemodynamic variables were measured to insure that right ventricular pressure overload had been produced. The hearts were then perfusion fixed, and papillary muscles from the right ventricle were prepared for light and transmission electron microscopy. Quantitative morphological data were obtained for the volume density both of several tissue components and of several organelles. It was found that there are significant increases in myocyte cross-sectional area and diameter in hypertrophied tissue with a concurrent increase in the volume density of interstitial tissue. There are no alterations in the volume density of organelles in the hypertrophied myocytes. We suggest that the substantial increase in the proportion of connective tissue and the decrease in the surface area to volume ratio that accompany pressure overload cardiac hypertrophy may be early underlying structural changes that relate directly to the abnormal contractile function found in this type of hypertrophy.

Animals↗
PubMed1983

Experimental studies on a lethal gene (t) in the Mexican axolotl, Ambystoma mexicanum.

In the Mexican axolotl, Ambystoma mexicanum, the developmental mutation lethal t is inherited as a simple Mendelian recessive. Mutant larvae failed to feed and died, on the average, 17 days after hatching. Unfed wild-type larvae died an average of 23 days after hatching. By 15 days, forelimb development had progressed further in the wild type; a cartilaginous scapula and humerus were present, but no cartilage was seen in the mutant limb. Histological examination indicated that the visceral cartilage may also be abnormal, and the rectus cervicus muscle was found to have fewer and smaller fibers. Though the mutant was not rescued by parabiosis with wild-type embryos, transplants of presumptive gill and limb tissue to wild-type hosts survived, indicating that the mutation is not an autonomous cell lethal.

Ambystoma↗
PubMed1983

Calculations of acoustic scattering from ellipsoidal voids: bends, krill and fish.

The T-matrix approach is used to calculate the scattering of sound waves by an ellipsoidal void in a fluid. Results are presented for the total cross-section of a sphere as a function of frequency; this is related to the detection of the onset of bends in divers. Results are also presented for the angular variation in scattered amplitude when a plane wave is incident on an ellipsoidal cavity in water; this is related to the target strength of euphausiids and teleostean. It is concluded that the model is a useful representation of the scattering from such marine organisms.

Animals↗