Sucrose consumption increases naloxone-induced c-Fos immunoreactivity in limbic forebrain.

Opioids have long been known to have an important role in feeding behavior, particularly related to the rewarding aspects of food. Considerable behavioral evidence suggests that sucrose consumption induces endogenous opioid release, affecting feeding behavior as well as other opioid-mediated behaviors, such as analgesia, dependence, and withdrawal. In the present study, rats were given access to a 10% sucrose solution or water for 3 wk, then they were injected with 10 mg/kg naloxone or saline. Brains were subsequently analyzed for c-Fos immunoreactivity (c-Fos-IR) in limbic and autonomic regions in the forebrain and hindbrain. Main effects of sucrose consumption or naloxone injection were seen in several areas, but a significant interaction was seen only in the central nucleus of the amygdala and in the lateral division of the periaqueductal gray. In the central nucleus of the amygdala, naloxone administration to those rats drinking water significantly increased c-Fos-IR, an effect that was significantly enhanced by sucrose consumption, suggesting an upregulation of endogenous opioid tone in this area. The data from this study indicate that the central nucleus of the amygdala has a key role in the integration of gustatory, hedonic, and autonomic signals as they relate to sucrose consumption, if not to food intake regulation in general. Furthermore, the data from this study lend further support to the hypothesis that sucrose consumption induces the release of endogenous opioids.

Effect of NPY in the hypothalamic paraventricular nucleus on uncoupling proteins 1, 2, and 3 in the rat.

Neuropeptide Y (NPY) injected into the hypothalamic paraventricular nucleus (PVN) stimulates feeding and decreases uncoupling protein (UCP)-1 mRNA in brown adipose tissue (BAT). The present studies were undertaken to determine whether UCP-2 in white adipose tissue (WAT) and UCP-3 in muscle are regulated by NPY in the PVN. PVN-cannulated male Sprague-Dawley rats were injected with either saline or NPY (PVN, 117 pmol, 0.5 microl) every 6 h for 24 h. NPY in the PVN stimulated feeding and decreased UCP-1 mRNA in BAT independent of NPY-induced feeding. UCP-2 mRNA in WAT was unchanged by NPY. In acromiotrapezius muscle, NPY decreased UCP-3 mRNA, but this was reversed by restricting food intake to control levels. In biceps femoris muscle, NPY alone had no effect on UCP-3 mRNA, but UCP-3 mRNA was significantly increased in the NPY-treated rats that were restricted to control levels of intake. These results suggest that UCP-2 in WAT and UCP-3 in muscle are not subject to specific regulation by NPY in the PVN.

Divergence of the feeding and thermogenic pathways influenced by NPY in the hypothalamic PVN of the rat.

Neuropeptide Y (NPY) injected into the paraventricular nucleus (PVN) increases feeding and decreases brown adipose tissue (BAT) uncoupling protein (UCP) and lipoprotein lipase (LPL) mRNA. Previously we reported that the feeding and BAT effects induced by NPY in the PVN are blocked by 50 microg naltrexone (NTX) in the rostral nucleus of the solitary tract (rNTS). We sought to determine whether the effect of rNTS NTX on PVN NPY-induced alterations in energy metabolism occurred at lower doses of NTX. Male Sprague-Dawley rats were fitted with cannulas into two sites: PVN and rNTS. Feeding response, BAT UCP, and LPL mRNA were measured after injection of 0, 5, 10, and 25 microg NTX in the rNTS +/- 1 microg NPY in the PVN. One-hour feeding response to PVN NPY was significantly and dose dependently decreased by 10 and 25 microg rNTS NTX (-23 and -31%, respectively). However, rNTS NTX did not block the PVN NPY-induced decrease in BAT UCP or LPL mRNA. BAT beta-actin mRNA (as a measure of overall changes in gene expression) was unchanged among treatment groups. These results indicate a possible divergence in the PVN NPY feeding-stimulatory/BAT-inhibitory pathway, such that PVN NPY feeding effects may be routed through the rNTS whereas BAT effects may be due to alterations at another neural site.

Neural site of leptin influence on neuropeptide Y signaling pathways altering feeding and uncoupling protein.

Inhibition of a signal that produces positive energy balance involving neuropeptide Y (NPY) projection from arcuate nucleus (Arc; site of NPY synthesis) to paraventricular nucleus (PVN; site of NPY release) is one potential mechanism of leptin action. NPY in the PVN increases feeding and decreases uncoupling protein (UCP) activity in brown fat, whereas leptin decreases NPY biosynthesis in the Arc, which presumably decreases PVN NPY. It is hypothesized that decreased NPY activity is necessary for the satiety and thermogenic effects of leptin. To test this, we first determined the effect of leptin on feeding in two paradigms: satiated rats and food-deprived rats. Leptin was effective in decreasing feeding in the satiated rats but ineffective in the food-deprived rats. Next, we determined that leptin decreases NPY and increases UCP gene expression. Finally, we injected leptin intracerebroventricularly before specific PVN NPY microinjection. We found that repletion of NPY in PVN by specific NPY microinjection reverses the feeding-inhibitory and thermogenic effects of centrally administered leptin, the first functional evidence indicating that leptin acts on the Arc-PVN feeding-regulatory pathway.

Naltrexone induces arcuate nucleus neuropeptide Y gene expression in the rat.

Neuropeptide Y (NPY) has potent effects on several components of energy metabolism, including increased feeding and decreased brown fat thermogenesis. Negative energy balance, such as food deprivation, increases NPY mRNA in hypothalamic arcuate nucleus (ARC). Naltrexone (NLTX), an opioid receptor antagonist, decreases NPY-induced feeding. We hypothesized that NLTX would alter ARC NPY mRNA and change NPY effects on brown fat. Osmotic minipumps prefilled with either saline or NLTX (70 micrograms/h) were implanted subcutaneously in 32 male Sprague-Dawley rats. One-half of the rats were food deprived and one-half were allowed food ad libitum for 48 h. Food intake was measured at 24 and 48 h. At 48 h, ARC NPY mRNA and brown fat uncoupling protein (UCP) mRNA levels were determined using cDNA probes. Forty-eight-hour food intake was significantly decreased by 24% after NLTX infusion. Food deprivation and NLTX treatment significantly and independently increased ARC NPY mRNA and decreased UCP mRNA levels in brown fat, suggesting a complex interaction between hypothalamic NPY and endogenous opioids in the regulation of energy balance.

Histochemical and electron microscopic characterization of hepatic macrophage subfractions isolated from normal and liposomal muramyl dipeptide treated rats.

Subfractions of the hepatic macrophage population, differing in cell size, were isolated from normal rats and rats treated with liposomal muramyl dipeptide (lipMDP) and analyzed histochemically and by ultrastructural peroxidase cytochemistry. The majority of cells in all subfractions of control rats displayed the ultrastructural endogenous peroxidase pattern of resident liver macrophages and showed positive staining with the general macrophage markers nonspecific esterase (NSE) and monoclonal antibody ED1. Heterogeneity in intensity of NSE and ED1 staining was observed among macrophages of different size. Generally, the intensity of NSE and ED1 staining decreased with decreasing cell size. After injection of lipMDP, we observed the appearance of a discrete subpopulation of cells in the liver in addition to the resident macrophages. These cells, containing a nucleus with a characteristic shape, were predominantly recovered in the small-sized fractions and were characterized by an immature ultrastructural macrophage morphology (no or only a few lysosomes and phagosomes) and a lack of ED1 reactivity, NSE, and endogenous peroxidase. We suggest an important role for these cells in lipMDP induced antitumor capacity of the liver.

Neuropeptide Y in hypothalamic paraventricular nucleus: a center coordinating energy metabolism.

Intracerebroventricular injection of neuropeptide Y (NPY) has two effects on energy metabolism in addition to increased feeding: decreased brown fat thermogenesis and increased white fat lipoprotein lipase (LPL) enzymatic activity. We hypothesized that the paraventricular nucleus (PVN) of the hypothalamus is the controlling neural site for these responses. We further hypothesized that NPY stimulation at PVN would reduce gene expression for the critical brown fat thermogenic protein, uncoupling protein (UCP), and increase gene expression for the key white fat storage enzyme, LPL. In the first experiment, three groups of rats received injections every 6 h for 24 h (5 injections total) into the PVN:1) NPY (1 micrograms/1 microliters injection) and ad libitum food; 2) NPY (1 micrograms/1 microliters injection) and food restricted to control intake; 3) saline injection (1 microliter) and ad libitum food. Both NPY-treated groups showed significant reductions (P < 0.05) in brown fat UCP mRNA levels and marked stimulation of LPL mRNA levels relative to controls. In the second experiment, four groups of seven rats had NPY injected into the PVN:0 (vehicle control); 0.1 microgram; 0.5 microgram; and 1 microgram. Injections were made every 6 h for 24 h. There was a dose-related reduction in UCP mRNA produced by the NPY treatment. NPY treatment increased LPL mRNA, but a smooth dosing effect was not evident. The observation that NPY in the PVN can coordinate more than one component of energy metabolism is significant when considered with many reports of responsiveness of NPY activity in the arcuate nucleus-PVN neural circuit to perturbations of energy balance such as fasting and feeding, diabetes, and genetic obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Injuries associated with MR imaging: survey of safety records and methods used to screen patients for metallic foreign bodies before imaging.

OBJECTIVE: The purpose of this study was to survey the methods used by academic institutions for identifying patients who might have metallic foreign bodies or other contraindications to MR imaging. We also sought to determine the types of MR-related injuries and any subsequent legal action that might have occurred at these institutions. MATERIALS AND METHODS: A survey on these issues was mailed to 207 academic institutions listed in the American Medical Association's Directory of Graduate Medical Education Programs. Institutions that did not respond by mail were contacted by phone. The survey requested information on the use of questionnaires, plain radiography, CT, and metal detectors for screening potential MR imaging subjects, as well as on any MR-related injuries and subsequent legal action. Responses were entered into a data base and response percentages were calculated for each question. RESULTS: The overall response rate for the survey was 99% (206/207). These 206 institutions have a total of 368 MR imaging units, with a mean number of 1.8 MR units per department (range, none to nine). Data from a total of 205 different sites revealed that all patients are screened before MR imaging with a written questionnaire at 93% of all institutions (190/205). For selected indications, 85% of departments (174/205) screen with plain film radiography of the orbits. For selected indications, 41% of facilities (83/205) screen with CT of the orbits. Patients are sometimes screened with a metal detector or magnetometer in 12% of the departments (24/205). Ten departments reported serious injuries relating to MR imaging. The most serious injury occurred when an oxygen tank near the magnet became a missile and struck a patient's face. Most injuries (nine of 14) were burns. Two institutions also reported adverse reactions to gadopentetate dimeglumine. Injuries prompted legal action against four of the 10 institutions. No injuries were related to intraorbital foreign bodies, vascular clips, or pacemakers in patients. CONCLUSION: These data demonstrate the lack of consensus on screening protocols before MR imaging. Accidents are uncommon, but most accidents that do occur are potentially severe and easily preventable. We recommend that all patients be screened by a written questionnaire followed by oral questioning before imaging to determine those who are at risk. Specific questions should investigate the possibility that patients have ferromagnetic foreign bodies or implants anywhere in the body that are electrically, magnetically, or mechanically activated. All facilities must maintain a high state of vigilance in an effort to prevent iatrogenic burns and injuries from ferromagnetic missiles.

Use of radiology in U.S. general short-term hospitals: 1980-1990.

PURPOSE: To determine changes in usage of radiologic services between 1980 and 1990. MATERIALS AND METHODS: Complete data were obtained from 107 (42%) hospitals and incomplete data from eight (3%) (total survey response rate, 45%). Information was requested about the number of general radiologic examinations; specific modalities of computed tomography (CT), magnetic resonance (MR) imaging, nuclear medicine, and ultrasonography (US); and numbers of CT, MR imaging, and US machines. RESULTS: The number of general radiologic examinations in hospitals increased from approximately 126 million to 179 million (> 42%); for CT, from 3.6 million to 13.3 million; nuclear medicine, from 6.4 million to 7.4 million; and US, from 4.3 million to 11.8 million. MR imaging examinations performed during 1990 were estimated at 1.8 million. CONCLUSION: The number of radiologic examinations performed in U.S. hospitals increased by 30%-60% between 1980 and 1990, mainly due to increased usage of CT, MR imaging, and US.

World War II military led the way in screening chest radiography.

World War I recruits were screened for tuberculosis almost exclusively with a history and physical exam. Radiography was unavailable on a large scale and expensive. New techniques developed in Brazil and elsewhere in the 1930s made mass radiographic screening practical. During World War II, the U.S. Army and Navy took advantage of this new technology to screen an estimated 10 million personnel. This ambitious and successful case-finding program inspired, in part, continuing radiographic screening efforts among the civilian population following the war, including mass screening of asymptomatic individuals and routine hospital admission chest films.

Glucagon in physiological concentrations stimulates brown fat thermogenesis in vivo.

Our aims were to further characterize the stimulatory effect of glucagon on brown fat and to test the hypothesis that physiological levels of hyperglucagonemia would stimulate brown fat thermogenesis. In the first set of experiments, glucagon (1 mg/kg sc twice daily) or vehicle control was administered three times in 26 h. This large dose of glucagon produced increases in GDP binding to brown fat mitochondria. In addition, Scatchard analysis indicated a glucagon-induced increase in number of GDP binding sites without evidence for alteration in binding site affinity. No consistent increase in brown fat mitochondrial GDP binding was produced 2 h after a single injection of glucagon (1 mg/kg). In the second set of experiments, glucagon was administered intraperitoneally by constant osmotic minipump infusion. Glucagon in a dose of 150 micrograms.kg-1.day-1 for 5 days produced significant increases in GDP binding to brown fat mitochondria, whereas glucagon serum levels were increased but stayed within the usual physiological range. A larger dose of glucagon administered by constant infusion virtually eliminated body weight gain over 7 days while significantly increasing nucleotide binding (GDP) to brown fat mitochondria. An important role for glucagon in thermogenic regulation is suggested.

Accuracy of common drug screen tests.

Forty consecutive urine specimens, obtained from patients seen in the emergency center, positive for either cocaine and/or marijuana, were analyzed using five methods of analysis. A new latex agglutination inhibition assay, Abuscreen OnTrak, (Roche Diagnostic Systems, Nutley, NJ), was compared with four other drug abuse assays: mass spectrometry, (Hewlett-Packard Co, Richardson, TX); an automated homogeneous enzyme immunoassay technique, ETS System, (Syva Co, Palo Alto, CA); a manual enzyme multiplied immunoassay technique; EMIT-st, (Syva); and a fluorescence polarization immunoassay, TDx, (Abbott Laboratories, Chicago, IL). For statistical purposes, mass spectrometry was the reference point for the presence or absence of a specific substance. All instrument sensitivities, with the exception of mass spectrometry, were set with the same "cut off" point of 100 micrograms/L for marijuana and 300 micrograms/L for cocaine and its metabolites. Efficiency in the detection of cocaine and its metabolites was 95% by all methods. Efficiency for the detection of marijuana and its metabolites ranged from 70% (Roche's OnTrak) to 90% (Syva's ETS). Simple to use, assays of minimal cost are presently available for rapid, accurate drug of abuse screening.

Effects of intracerebroventricular injection of neuropeptide Y on energy metabolism.

Our objective was to find out if central injection of neuropeptide Y (NPY) would alter brown fat thermogenesis and white fat lipoprotein lipase activity. The following three groups of Sprague-Dawley rats received five injections over 24 h into the right lateral ventricle: 1) NPY (5 micrograms/injection) and ad libitum food; 2) NPY (5 micrograms/injection) and food restricted to control intake; 3) saline injection and ad libitum food. The NPY ad libitum-fed group consumed more food than the saline controls or NPY food-restricted animals. Brown fat thermogenic activity, assessed by GDP binding, was decreased relative to saline controls in both NPY-treated groups. White fat lipoprotein lipase activity was greatly increased in both NPY treatment groups compared with saline controls. The NPY effects on brown and white fat were not explained by measures of serum insulin, glucagon, glucose, or other metabolites. In a follow-up experiment, we asked whether food was necessary for expression of the NPY effects. Brown fat mitochondrial GDP binding indicated NPY effect even when no food was ingested. We conclude that intracerebroventricular administration of NPY promotes white fat lipid storage and decreases brown fat thermogenesis in addition to its known effect of stimulating food intake.

The effects of chronic obstructive airways disease on the ability to drive and to use a roadside alcolmeter.

Subjects with chronic obstructive airways disease may have difficulty with the roadside alcolmeter. Twenty-six subjects with a FEV1/FVC less than 60% were asked to use an alcolmeter simulator. Only ten were able to produce the necessary flow rate of 28 l min-1 for a minimum of 2.7 s, two could produce the same total volume (1.25 l) at 10 l min-1 for 7.5 s, five could only expel 10 l min-1 for 4.5 s, and nine were unable to trigger the alcolmeter at even these very low flow rates. Subjects with an FEV1 of less than 1.51 or FEV1% predicted less than 50% were very unlikely to be able to activate the alcolmeter. Ten healthy subjects were investigated to assess the accuracy of the roadside alcolmeter at a flow rate of 10 l min-1 compared to 40 l min-1. No significant difference was found in breath alcohol levels between the two flow rates. It is proposed that some modification could be made to the roadside alcolmeter, without affecting its accuracy, to allow some subjects with chronic obstructive lung disease to activate the device. A postal survey of 284 subjects with a FEV1/FVC less than 60% was carried out. Of those who were drivers or exdrivers, 24.7% had had to stop or reduce their driving because of their respiratory disease. This group had a significantly lower FEV1% predicted (P = 0.035) than those whose driving was unaffected.

A histochemical study about the involvement of rat liver cells in the uptake of heterologous immune complexes from the circulation.

Intravenously injected immune complexes (ICx) composed of bovine serum albumin (BSA) and rabbit anti-BSA were taken up by the liver. Insoluble complexes, made in antibody excess, were rapidly taken up by Kupffer cells and were metabolized within 24 h. Soluble complexes, made in antigen excess, were only partly taken up by Kupffer cells. In addition these complexes were bound, taken up and metabolized by endothelial cells. Until 2 h after injection soluble complexes could also be observed along the microvilli of hepatocytes. No signs of endocytosis in hepatocytes could be observed. It is concluded, that ICx can be taken up by Kupffer cells as well as by endothelial cells. The physical state of the complexes, soluble or insoluble, determines the cell type in which uptake occurs.

Langerhans' cells and macrophages in eosinophilic granuloma. An enzyme-histochemical, enzyme-cytochemical, and ultrastructural study.

Biopsy material of six patients with eosinophilic granuloma (EG) was investigated by electron microscopic and enzyme-histochemical methods for acid phosphatase (AcP), leucyl-beta-naphthylamidase (LA), adenosine triphosphatase, and alpha-naphthyl-acetate esterase (NE). Paraplast sections were used for demonstration of lysozyme with an immunoperoxidase method. Results of staining for these different enzymes suggested the existence of two separate sets of histiocytic cells: one type with "dot-like" AcP staining and negative for NE and lysozyme; and the other with diffuse AcP staining, positive for NE and lysozyme, and often showing signs of phagocytosis. The first type presumably represented Langerhans' cells and also often showed positive staining for LA. Macrophages were generally negative for LA. Electron microscopic study confirmed the impression gained from enzyme-histochemical studies. No intermediate cell types between Langerhans' cells and genuine macrophages were seen. From these results it is concluded that in EG no transformation exists between Langerhans' cells and macrophages. The latter are presumably of reactive nature.

Variables affecting measurement of human red cell Na+,K+ATPase activity: technical factors, feeding, aging.

Because it has been suggested that decreased activity at the erythrocyte sodium pump might be the cause of age-related decreases in basal oxygen consumption, we have examined age-associated changes in Na+,K+-ATPase activity in red cell membranes. The initial portion of this study was directed toward elucidating possible methodological pitfalls in membrane preparation which might account for some of the variable results reported in prior erythrocyte Na+,K+-ATPase studies. We found that two of four red cell membrane fractions have substantial Mg2+-ATPase activity and contribute a significant portion of total membrane protein. As these two fractions contain little Na+,K+-ATPase activity their contamination of the other two fractions could cause significant variation in measured Na+,K+-ATPase activity. Additionally, we found that meal feeding raised Na+,K+-ATPase activity necessitating that measurements be made in the fasting state. With these methodological variables controlled, we found only a 10.8% coefficient of variation between fasting samples obtained on separate days in eight subjects. Using this methodology, we observed no correlation of Na+,K+-ATPase specific activity with age in males, and only a weak correlation in females who showed decreasing Na+,K+-ATPase specific activity occurring with advancing age. These observations suggest that changes in erythrocyte Na+,K+-ATPase activity do not cause the age-related fall in basal oxygen consumption.