Nutrition
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Review
Hypothalamic neuronal histamine: implications of its homeostatic control of energy metabolism.
In a series of studies on histaminergic functions in the hypothalamus, probes to manipulate activities of histaminergic neuron systems were applied to assess its physiologic and pathophysiologic implications using non-obese normal and Zucker obese rats, an animal model of genetic obesity. Food intake is suppressed by either activation of H1-receptor or inhibition of the H3-receptor in the ventromedial hypothalamus (VMH) or the paraventricular nucleus, each of which is involved in satiety regulation. Histamine neurons in the mesencephalic trigeminal sensory nucleus modulate masticatory functions, particularly eating speed through the mesencephalic trigeminal motor nucleus, and activation of the histamine neurons in the VMH suppress intake volume of feeding at meals. ⋯ Abnormalities produced by depletion of neuronal histamine from the hypothalamus in normal rats mimic those of obese Zuckers. Grafting the lean Zucker fetal hypothalamus into the obese Zucker pups attenuates those abnormalities. These findings indicate that histamine nerve systems in the brain play a crucial role in maintaining homeostatic energy balance.
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Although intravascular devices have become indispensable tools in the care of seriously ill patients, the morbidity and mortality resulting from catheter-related infections and the high cost of managing such complications may offset the benefits derived from these devices. A scientific understanding of the pathogenesis, microbiology, and risk factors involved in catheter-related infection is the cornerstone of any effective preventive approach. ⋯ The first approach does not use antimicrobial agents and includes measures such as placement and maintenance of vascular catheters by a skilled infusion therapy team and use of maximal sterile barriers. The second approach uses antimicrobial agents and involves the application of topical disinfectants such as chlorhexidine, use of silver-impregnated subcutaneous cuffs (for short-term central venous catheters), flushing catheters with a combination of antimicrobial and antithrombotic agents, and coating of catheters with either antiseptic (chlorhexidine and silver sulfadiazine) or antimicrobial agents (minocycline and rifampin).
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Randomized Controlled Trial Clinical Trial
Six-month outcome of critically ill patients given glutamine-supplemented parenteral nutrition.
An abundant amino acid in the human body, glutamine (Gln) has many important metabolic roles that may protect or promote tissue integrity and enhance the immune system. Low plasma and tissue levels of Gln in the critically ill suggest that demand may exceed endogenous supply. A relative deficiency of Gln in such patients could compromise recovery and result in prolonged illness and an increase in late mortality. ⋯ The excess control deaths occurred later and those patients had had a significantly longer postintervention stay (P = 0.012) and use of ICU. In the Gln recipients, the total ICU and hospital cost per survivor was reduced by 50%. In critically ill ICU patients unable to receive enteral nutrition, a Gln-containing PN solution improves survival at 6 mo and reduces the hospital costs per survivor.
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The prevention of catheter sepsis lies in a sound understanding of the routes through which catheters get contaminated. The catheter hub has been recognized as a portal for microorganisms causing catheter sepsis, particularly in central venous catheters inserted for > 1 wk. Bacteria and fungi may reach the internal surface of the catheter connector during manipulation by hospital staff and then colonize the entire lumen of the catheter. ⋯ Needleless systems must be evaluated in terms of their safety in preventing endoluminal contamination. A new disinfecting catheter hub incorporating an antiseptic barrier has been developed and reduced hub-related catheter sepsis by more than 90%. The endoluminal route of intravascular catheter contamination must be taken into account when designing strategies for the diagnosis and prevention of catheter-related sepsis.
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The availability and widespread use of TPN enables physicians to help patients in a way that had not been possible in the past. However, in order to best utilize this modality, we must be aware of potential hazards and metabolic complications. Many patients receiving TPN, particularly those receiving perioperative TPN, are malnourished to various extents, and careful monitoring of glucose metabolism is warranted to avoid malnutrition-associated reactive hypoglycemia.