PubMed Health⌕ Search

Biomedical subjects

A Dicker

Publications and source records attributed to A Dicker.

28 records · Page 2Linked to original sources
PubMed1995

Polyunsaturated fatty acids recruit brown adipose tissue: increased UCP content and NST capacity.

To examine the effect of polyunsaturated fatty acids (PUFA) on brown adipose tissue recruitment and on the capacity for nonshivering thermogenesis (NST), mice were fed a diet with a standard fat content (9%) and a normal PUFA content (1.6%) (controls) or a high-PUFA content (4.3%) for 2-3 wk. The resting metabolic rate was somewhat lower in the high-PUFA group, probably due to a lower physical activity whereas the capacity for NST (estimated as the metabolic response to a norepinephrine injection) was higher in the high-PUFA group. There was no significant effect on brown adipose tissue wet weight, protein content, or cytochrome-c oxidase content, but the amount of the uncoupling protein thermogenin (UCP), measured immunologically, was significantly increased in the high-PUFA mice (totally by 41%). It was concluded that short-term feeding of a high-PUFA diet may recruit brown adipose tissue thermogenic capacity; it was speculated that earlier-reported recruiting effects of high-fat diets may not be due solely to the high total fat content of the diet but perhaps also to a specific recruiting property of the high-PUFA diets generally used in this type of investigation.

Adipose Tissue, Brown↗
PubMed1995

Cold acclimation-recruited nonshivering thermogenesis: the Syrian hamster is not an exception.

Biochemical evidence from in vitro studies of brown adipose tissue in Syrian hamsters indicates a significant degree of recruitment of the tissue as an effect of cold acclimation. However, earlier in vivo studies indicate a lack of recruitment of nonshivering thermogenesis in the intact animal as a result of cold acclimation. Because of this apparent discrepancy, the occurrence of cold acclimation-recruited nonshivering thermogenesis in hamsters was investigated. Hamsters were cold acclimated to 6 degrees C or remained at 24 degrees C (controls), and their thermogenic response was investigated in an open-circuit system at 24 degrees C. Cold acclimation resulted in a small increase in resting metabolic rate and a major increase in the thermogenic response to norepinephrine (61% increase over resting metabolic rate in controls and 156% increase in cold-acclimated animals). The absolute beta 3-specific adrenergic agonist CGP-12177 also induced a high rate of nonshivering thermogenesis, which was similarly recruited. It was concluded that, concerning the relative effect of recruitment on the capacity for nonshivering thermogenesis, the intact hamsters responded as would be predicted from in vitro experiments. Thus the hamster does not seem to constitute an exception to the general patterns described for other rodents concerning recruitment of nonshivering thermogenesis due to cold acclimation.

Acclimatization↗
PubMed1992

Increased alpha 1-adrenoceptor density in brown adipose tissue indicates recruitment drive in hypothyroid rats.

The effects of hypothyroidism on whole body thermogenesis, brown adipose tissue recruitment state, and alpha 1-adrenergic receptor density were investigated. Treatment of rats with methimazole for 4-5 wk led, as expected, to reduction of growth and resting metabolic rate. The thermogenic response to norepinephrine injection was practically abolished. Generally, only small effects of hypothyroidism on brown adipose tissue were observed: total protein content, mitochondrial GDP binding capacity, and total content of the uncoupling protein thermogenin were not altered. The density of beta-adrenergic receptors (estimated with [3H]CGP-12177 as a ligand) was also unchanged. However, the density of alpha 1-adrenergic receptors (estimated with [3H]prazosin) was markedly increased; in other physiological conditions, such an increase has been associated with an increased degree of recruitment of the tissue. These data indicate that brown adipose tissue in the subthermoneutral hypothyroid animal, probably due to homeostatic mechanisms, is exposed to an increased sympathetic stimulation, leading to an increased alpha 1-adrenoceptor density. However, other features of recruitment are only poorly induced, probably due to attenuation of the beta-adrenergic signaling mechanism. The increased alpha 1-adrenergic receptor density may be responsible for certain altered features of brown adipose tissue in hypothyroid animals, such as peroxisomal recruitment and perhaps also for maintenance of the thermogenin content. The results also indicate that the increased alpha 1-adrenergic density generally seen in recruitment would not result from chronic beta-adrenergic stimulation of the tissue but may be controlled via another regulatory pathway, e.g., via the alpha 1-adrenergic pathway itself.

Adipose Tissue, Brown↗
PubMed1989

The beta-adrenergic radioligand [3H]CGP-12177, generally classified as an antagonist, is a thermogenic agonist in brown adipose tissue.

The effect of CGP-12177, originally developed as a radioligand with antagonist properties for binding studies of beta-adrenergic receptors, was investigated in brown adipose tissue. Contrary to expectations, CGP-12177 showed clear agonist properties in experiments with hamster brown-fat cells, with a maximal effect in stimulating oxygen consumption similar to that of the physiological stimulator noradrenaline, and also with a potency similar to that of noradrenaline [EC50 (50% effective concn.) approx. 70 nM]. This value could be contrasted with the very high affinity of CGP-12177 (KD about 1 nM) for ligand-binding sites on the cells. It is therefore suggested that the high-affinity binding site may not be the one that mediates the CGP-12177-stimulated thermogenesis in isolated cells. Also, when injected into cold-adapted rats, CGP-12177 stimulated non-shivering thermogenesis similarly to noradrenaline. This observation, in conjunction with the reported low general sympathomimetic effect of CGP-12177, may indicate that CGP-12177 could be of interest for the development of anti-obesity drugs.

Adipose Tissue, Brown↗
PubMed1985

Amebic liver abscess: a study of 11 cases compared with a series of 38 patients with pyogenic liver abscess.

Amebic liver abscess is an uncommon disease in the northern states of North America with 11 cases seen among approximately 500,000 Mount Sinai Hospital admissions over a 16-year period. Five of 11 cases originated in, or had recently visited South America. In three of these, and two patients with concomitant intestinal amebiasis, the diagnosis was suspected on admission. Diagnosis after admission was rapid, mean 5 days, compared with a mean of 13 days in pyogenic liver abscess. There was a higher incidence of male patients, nine males versus two females which was greater than the excess found in our pyogenic abscesses, 22 versus 16. Multiplicity was less common than in pyogenic abscess, 27 versus 50%, respectively. All three patients with multiple abscesses survived with surgical drainage and antibiotic therapy despite numerous complicating factors, including secondary bacterial infection. One patient resolved with drug treatment only; all others were treated with drugs and concomitant drainage; surgical drainage in earlier cases, and percutaneous drainage more recently. There was a single postoperative death. Drug treatment is the first therapeutic modality, and if recovery is delayed more than 2 days percutaneous aspiration should be carried out. This was successful in four cases. Surgery should seldom be required with present methods of accurately localizing amebic liver abscess, but is essential for ruptured abscess with peritonitis, and liver abscess with associated intestinal problems such as toxic megacolon, colonic perforation, or fulminating colitis. There has been a significant reduction in mortality of amebic liver abscess over the past 50 years and particularly within the past decade.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Periileostomy fistulae in Crohn's disease.

Fifteen of 214 patients with an ileostomy constructed during the course of Crohn's disease developed periileostomy fistulae. In each case this was the consequence of recurrent ileal disease. The incidence was higher in female patients as well as those with a prior history of either intraabdominal abscess or any type of fistula. Periileostomy fistulae are frequently multiple. In addition to the clinical features of recurrent disease, periileostomy fistulae cause additional symptoms that are particularly distressing. These result from the proximity of the fistula to the stoma and the difficulty of maintaining the seal of an appliance. All periileostomy fistulae require resection and reconstruction of the stoma. Superficial fistulae with relatively smooth skin around the stoma may be reconstructed using the original stoma site; but deep fistulae with severe peristomal excoriation, induration and inflammation require transposition to a different quadrant. This may, in suitable cases, be carried out by direct stoma-to-stoma transposition, without formal laparotomy. The quality of life following successful reconstruction of the stoma is excellent, even though some patients will develop additional recurrent disease. To date none of these patients have developed another periileostomy fistula.

Adolescent↗
PubMed1981

Noninvasive detection of left ventricular dysfunction with a portable electrocardiographic gated scintillation probe device.

A comparison of left ventricular function data derived from a low cost, portable electrocardiographic gated scintillation probe (nuclear stethoscope) with conventional scintiangiographic data was performed in 68 patients. Ejection fraction correlation (r = 0.86, p less than 0.005) was better in patients with uniform wall motion than in those with regional asynergy (r = 0.68 p less than 0.01). Probe variables reflecting systolic emptying rates, diastolic filling rates and timing intervals, and relative volumes analyzed in combination provided 100 percent sensitivity, specificity, and predictive value in detecting abnormal left ventricular performance. The results suggest that radionuclide angiography with an electrocardiographic gated scintillation probe is a sensitive, rapid and relatively inexpensive portable method of screening for cardiac dysfunction with a yield similar to that from the more costly gamma camera derived scintiangiogram.

Electrocardiography↗