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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five models predicting shivering thermogenesis on the basis of steady state skin and core temperature were evaluated: Hayward et al., Stolwijk and Hardy,; Nadel et al.,; Timbal et al., and Brown and Brengelmann, using the empirical data derived from a cold water immersion study by Morrison et al. A residual analysis indicated that all models generated substantial errors of prediction. The best overall predictors were expressions suggested by Hayward et al., while the predictive equation of Nadel et al. ranked second. Derivation of personal coefficients significantly improved the prediction of all models and a subsequent modification of the standard models, adding temperature derivative terms, further reduced the magnitude of the error. An analysis of the residuals indicated that peripheral and core temperatures should be weighted according to the characteristics of thermosensitive neural structures in these regions.
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PMID:Evaluation of predictive formulae for determining metabolic rate during cold water immersion. 374 Dec 91

Brown fat lipoprotein lipase activity did not change in the first two weeks of pregnancy whereas it decreased on day 18 of gestation and was lower during late pregnancy and lactation. Fatty acid synthesis rate, measured in vivo with (3H)H2O, showed a progressive increase until day 18 of gestation followed by a decrease on day 20 of pregnancy and a reduced lipogenesis rate throughout lactation. The early reduction in the pathways of fatty acid uptake and synthesis in brown fat during the breeding cycle of the rat suggests the possibility that a decline in the substrate supply was a factor contributing to the reduced thermogenic activity of brown adipose tissue after parturition.
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PMID:Changes in brown adipose tissue lipoprotein lipase activity and lipogenesis rate during pregnancy and lactation in the rat. 379 Jan 43

The effects of protein dehydration upon the equilibrium and dynamic properties of the heme active site in human hemoglobin (HbA) have been probed by resonance Raman scattering. Spectra of equilibrium carbonmonoxy-HbA and the photolytic heme transient species generated within 10 ns of ligand photolysis have been obtained from thin films of protein in various stages of dehydration. These data provide detailed information concerning the response of the heme and its bonding interactions with both the proximal histidine and carbon monoxide as a function of protein hydration. For protein hydration levels of 0.4-1.0 g of H2O/g of protein, our results indicate that the C = O stretching mode of carbonmonoxy-HbA is dramatically affected by protein hydration levels, thus corroborating the infrared results of Brown et al. [Brown, W. E., Sutcliffe, J. W., & Pulsinelli, P. D. (1983) Biochemistry 22, 2914-2923]. However, we find that both heme skeletal modes and the Fe-C bond strength are largely insensitive to dehydration. Moreover, the proximal pocket geometry (as reflected in the behavior of the Fe-proximal histidine stretching mode) immediately following ligand photolysis was found to be very similar to that of R-state solution hemoglobin. At protein hydration levels below the theoretical monolayer limit, small changes in the resonance Raman spectra of both equilibrium HbCO and the transient heme species generated subsequent to ligand photolysis are detected. These include broadening of the Fe-C stretching mode in equilibrium HbCO and a small shift to lower frequency of the Fe-His mode in the photolytic transient species.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Response of the local heme environment of (carbonmonoxy)hemoglobin to protein dehydration. 380 49

Gastric intubation of young male rats with 100 kJ/d of medium chain (C8 and C10) triglyceride (MCT) reduced their voluntary intake of stock diet such that total metabolizable energy intake was similar to that of rats intubated with water, and 41% of their energy intake was derived from MCT. Body weight, energy gain, and energetic efficiency were all markedly suppressed in MCT-fed rats, but energy expenditure over the 14-day experiment was significantly increased. Resting oxygen consumption, measured at thermoneutrality, was also enhanced in MCT-fed rats, but this difference was abolished by injection of the animals with the beta-adrenergic antagonist, propranolol. Brown adipose tissue mass was similar for both groups, but the activity of the mitochondrial proton conductance pathway, assessed from the binding of purine nucleotides, was increased by over 70%. These data indicate that the reduced weight gains of animals fed MCT are due to elevated rates of energy expenditure, possibly resulting from sympathetic activation of brown fat thermogenesis.
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PMID:Stimulation of thermogenesis and brown fat activity in rats fed medium chain triglyceride. 380 85

We undertook this study to determine whether radiation (10 Gray, single dose) or water bath hyperthermia (41 degrees C, 45 min) could enhance binding of 111In-labeled anti-p97a monoclonal antibody (MAb) to human melanoma tumors transplanted subcutaneously into nude mice. Sixty animals were given injections of 1-2 X 10(7) Brown C5513 melanoma cells. At 1-2 weeks postinjection, two-thirds of the mice were treated (one-third served as controls). Within 3 hours after treatment, each animal was given iv 2 muCi 111In-anti-p97a MAb. At 24 and 48 hours thereafter, whole-body scans were done with the use of a MaxiCamera 300 A/M unit, and the ratio of activity at the tumor and liver was determined. Some animals were kept for 7 days posttreatment, whereas others were taken after the 48-hour scan for determination of biodistribution of the radiolabeled complex. Enhancement of MAb binding was demonstrated by either modality, although enhancement was more consistent with radiation. The therapeutic efficacy of MAb may be enhanced with increased binding of radioactive MAb complexes through single dose radiation or hyperthermia.
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PMID:Enhancement of monoclonal antibody binding to melanoma with single dose radiation or hyperthermia. 382 18

We reported a case of senile dementia, Alzheimer type, with groping in response to a visual stimulus ("visual groping"). T.S. was a right-handed woman, 69 years old. In the beginning she displayed "visual groping" of the right hand, besides aphasia, lowered registration and Casteigne's "Motor neglect" of the right upper extremity. As the disease progressed, "visual groping" of the left hand developed, followed by "forced grasping" of the left hand. When the patient was 62 years old, she first showed decreased volition and lowered registration. Later poor finger movement and lessened speech were marked. At the age of 69, she was admitted to our hospital with aphasia and reduced registration. The patient showed preservation in naming and drawing tests. She also displayed a "visual groping" phenomenon of the right hand. This phenomenon was revealed when an examiner displayed something about 50 cm in front of the patient, and then she extended the upper extremity gropingly. We considered this phenomenon as "groping in response to a visual stimulus" of Denny-Brown. At the same time, the motor or praxic disorder of this patient consisted of paucity of movement. When she was told to imitate, her right upper extremity was hardly utilized, although later movements could be realized by her practice. When she was told to pour water from one glass into another, she used her left hand, although she used her right hand for spontaneous actions. So we considered this dyspraxia as a motor neglect of Casteigne.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The groping phenomena in a case of Alzheimer type dementia]. 382 42

Measurements of the magnetic field dependence of the longitudinal nuclear magnetic relaxation rates of solvent protons (NMRD profiles) in solutions of paramagnetic proteins have contributed significantly to the elucidation of the physical biochemistry of a number of metalloprotein systems. In many cases, NMRD profiles were used as indicators of chemical state, both static and dynamic [cf. Brewer, C. F., Brown, R. D., III, & Koenig, S. H. (1983) J. Biomol. Struct. Dyn. 1, 961-997], in part because a proper theoretical description of the data, with realistic assumptions for a model system, was computationally intractable. This has been particularly true for Cu2+-protein complexes, attributable in part to the S = 1/2 ground-state configuration of the Cu2+ ions; significant progress in interpreting such data has been made only recently [Bertini, I., Briganti, F., Luchinat, C., Mancini, M., & Spina, G. (1985) J. Magn. Reson. 63, 41-55]. We report NMRD profiles for solutions of Cu2+ - and VO2+-substituted human transferrin, both S = 1/2 ions, as well as computations that include the effects of the anisotropic hyperfine interactions of the paramagnetic ions with their respective nuclei. The description of the data that results from these computations is quite good, sufficiently so that one can say with confidence that the protons that contribute to the relaxation are rather distant (approximately 3.5 A) from the ions and in rapid exchange (approximately 10(8) s-1) with solvent. A possible view, consistent with what is known of the biochemistry of these substituted transferrins, is that relaxation occurs in the second coordination sphere: the exchanging entity is a water molecule hydrogen bonded to a donor atom of the metal ion complex.
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PMID:Magnetic relaxation of solvent protons by Cu2+- and VO2+-substituted transferrin: theoretical analysis and biochemical implications. 387 26

The winter athlete has several potential tactics for sustaining body temperature in the face of severe cold. An increase in the intensity of physical activity may be counter-productive because of increased respiratory heat loss, increased air or water movement over the body surface, and a pumping of air or water beneath the clothing. Shivering can generate heat at a rate of 10 to 15 kJ/min, but it impairs skilled performance, while the resultant glycogen usage hastens the onset of fatigue and mental confusion. Non-shivering thermogenesis could arise in either brown adipose tissue or white fat. Brown adipose tissue generates heat by the action of free fatty acids in uncoupling mitochondrial electron transport, and by noradrenaline-induced membrane depolarisation and sodium pumping. The existence of brown adipose tissue in human adults is controversial, and although there are theoretical mechanisms of heat production in white fat, their contribution to the maintenance of body temperature is small. Acclimatisation to cold develops over the course of about 10 days, and in humans the primary change is an insulative, hypothermic type of response; this reflects the intermittent nature of most occupational and athletic exposures to cold. Nevertheless, with more sustained exposure to cold air or water, humans can apparently develop the humoral type of acclimatisation described in small mammals, with an increased output of noradrenaline and/or thyroxine. The associated mobilisation of free fatty acids suggests the possibility of using winter sport as a pleasant method of treating obesity. In men, a combination of moderate exercise and facial cooling induces a substantial fat loss over a 1- to 2-week period, with an associated ketonuria, proteinuria, and increase of body mass. Possible factors contributing to this fat loss include: (a) a small energy deficit; (b) the energy cost of synthesising new lean tissue; (c) energy loss through the storage and excretion of ketone bodies; (d) catecholamine-induced 'futile' metabolic cycles with increased resting metabolism; and (e) a specific reaction to cold dehydration. Current limitations for the clinical application of such treatment include uncertainty regarding optimal environmental conditions, concern over possible pathological reactions to cold, and suggestions of a less satisfactory fat mobilisation in female patients. Possible interactions between physical fitness and metabolic reactions to cold remain controversial.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Adaptation to exercise in the cold. 388 60

No reliable, noninvasive technique is currently available for the early detection of cardiac transplant rejection. In this study, pulse nuclear magnetic resonance (NMR) spectroscopy was used (20 MHz) to detect cardiac allograft rejection in rats. Proton spin-lattice relaxation time (T1), proton spin-spin relaxation time (T2), and water content were measured in both recipient and donor hearts at 2, 4, 6, and 8 days after transplantation. Pathologic specimens were scored on a 0 to 4+ scale of increasing evidence of rejection by light microscopy. Three kinds of heterotopic transplants were performed for a total of 90: (1) Lewis rats received Lewis rat isografts, (2) Lewis rats received Brown Norway rat allografts, and (3) Lewis rats received cyclosporin A-treated allografts (15 mg/kg/day). T1 in group 2 was significantly higher than that in group 1 as early as day 2 (670 + 25 vs 616 + 11 msec, p less than .001), when histologic scores were not different. T2 in group 2 was also higher than that in group 1 (48.0 +/- 5.0 vs 41.1 +/- 2.6, p less than .005). T1 and T2 in group 2 increased from day 4 and correlated well with the water content of the hearts (r = .70 and r = .75, respectively). Cyclosporin A completely suppressed the increase of T1 and T2 in group 2. Treatment with cyclosporin also suppressed the histologic rejection scores. Our data suggest that proton relaxation time measurement may be a sensitive technique for detecting the onset of rejection and examining the therapeutic effects of cyclosporin. NMR imaging, which highlights T1 and T2 separately, should provide a sensitive noninvasive means of assessing myocardial graft rejection.
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PMID:Early detection of cardiac allograft rejection with proton nuclear magnetic resonance. 389 56

The ability of proton NMR relaxation times to detect cardiac allograft rejection was studied in an inbred rat heterotopic cardiac transplantation model. Hearts from 25 Lewis X Brown Norway F1 hybrid rats were anastomosed to the abdominal aorta and vena cava of Lewis recipients; 25 Lewis donor hearts served as isograft controls. Groups of five allografts and five isografts were harvested daily between two and six days post-transplant. The relaxation times T1 and T2 of the transplanted hearts were determined in vitro with a 10 MHz spectrometer. T1 and T2 values in allografts did not differ significantly from those in isografts at days 2 and 3 post-transplant. However, at days 4, 5, and 6 T1 and T2 of the allografts were significantly prolonged. This finding correlated with an elevation in tissue water content and the onset of rejection as determined histologically. An additional 21 allografts, treated with cyclosporine, were studied in the same way from four to more than 100 days post-transplant. T1 and T2 values of these treated allografts did not change significantly during the observation period and were similar to the relaxation values obtained in the isografts at days 2 to 6. These data suggest that serial measurements of myocardial T1 and T2 may be useful in detecting acute cardiac allograft rejection and monitoring the effect of antirejection treatment.
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PMID:The detection of cardiac allograft rejection by alterations in proton NMR relaxation times. 390 83


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