Inverse association of high-fat diet preference and anxiety-like behavior: a putative role for urocortin 2.

The aim of this study was to investigate whether the preference for a palatable high-fat diet (HFD) is associated with response to novelty and with anxiety-like behavior in rats and whether such fat preference correlates with gene expression of hypothalamic neuropeptides related to feeding. We subjected male rats to two tests of exploration of novel environments: the multivariate concentric square field (MCSF) and the elevated plus maze (EPM). The rats were then exposed to a 5-day test of preference for a palatable HFD versus reference diets. Messenger RNA (mRNA) levels of 21 neuropeptides were investigated by quantitative polymerase chain reaction. We found a strong positive correlation of HFD preference and open-arm activity in the EPM (% open-arm time, r(s) = 0.629, df = 26, P < 0.001). Thus, HFD preference was inversely associated with anxiety-like behavior. The same association was found for HFD preference and behavior in the MCSF (bridge entries, r(s) = 0.399, df = 23, P = 0.048). In addition, the HFD preference was positively correlated (r(s) = 0.433, df = 25, P = 0.021) with hypothalamic mRNA levels of urocortin 2 (Ucn 2). Moreover, behavior in the EPM was significantly correlated with expression levels of the receptor for Ucn 2, the corticotropin-releasing factor receptor 2, in the hypothalamus (r(s) = 0.382, df = 33, P = 0.022, pituitary (r(s) = 0.494, df = 31, P = 0.004) and amygdala (r(s) = 0.381, df = 30, P = 0.032). We conclude that preference for palatable HFD is inversely associated with anxiety and propose that Ucn 2 signaling may play a role in this association.

Elevated hypothalamic orexin signaling, sensitivity to orexin A, and spontaneous physical activity in obesity-resistant rats.

Selectively-bred obesity-resistant [diet resistant (DR)] rats weigh less than obesity-prone [diet-induced obese (DIO)] rats, despite comparable daily caloric intake, suggesting phenotypic energy expenditure differences. Human data suggest that obesity is maintained by reduced ambulatory or spontaneous physical activity (SPA). The neuropeptide orexin A robustly stimulates SPA. We hypothesized that DR rats have greater: 1) basal SPA, 2) orexin A-induced SPA, and 3) preproorexin, orexin 1 and 2 receptor (OX1R and OX2R) mRNA, compared with DIO rats. A group of age-matched out-bred Sprague-Dawley rats were used as additional controls for the behavioral studies. DIO, DR, and Sprague-Dawley rats with dorsal-rostral lateral hypothalamic (rLHa) cannulas were injected with orexin A (0, 31.25, 62.5, 125, 250, and 500 pmol/0.5 microl). SPA and food intake were measured for 2 h after injection. Preproorexin, OX1R and OX2R mRNA in the rLHa, and whole hypothalamus were measured by real-time RT-PCR. Orexin A significantly stimulated feeding in all rats. Orexin A-induced SPA was significantly greater in DR and Sprague-Dawley rats than in DIO rats. Two-mo-old DR rats had significantly greater rLHa OX1R and OX2R mRNA than DIO rats but comparable preproorexin levels. Eight-mo-old DR rats had elevated OX1R and OX2R mRNA compared with DIO rats, although this increase was significant for OX2R only at this age. Thus DR rats show elevated basal and orexin A-induced SPA associated with increased OX1R and OX2R gene expression, suggesting that differences in orexin A signaling through OX1R and OX2R may mediate DIO and DR phenotypes.

Paraventricular hypothalamic alpha-melanocyte-stimulating hormone and MTII reduce feeding without causing aversive effects.

alpha-Melanocyte-stimulating hormone (alpha-MSH) appears to play a tonic inhibitory role in feeding and energy storage. MTII, a specific synthetic MC3-R/MC4-R agonist, has similar effects on feeding in rats. The current studies demonstrate that PVN administration of alpha-MSH or MTII decreases nocturnal and NPY-stimulated food intake without causing aversive effects. Co-administration with NPY of 600 pmol alpha-MSH or 1 pmol MTII into the PVN caused a significant decrease in NPY-induced feeding. PVN administration of MTII or alpha-MSH at doses effective to suppress feeding did not cause conditioned taste aversion (CTA). ICV administration of alpha-MSH, however, did cause weak CTA. These results indicate that the potent effects on feeding of MC3-R and MC4-R agonists when injected into the PVN are not due to aversive effects.

Fos expression in feeding-related brain areas following intracerebroventricular administration of orphanin FQ in rats.

While the influence of orphanin FQ (OFQ) on the regulation of food intake has been substantiated, little is known about feeding-related brain regions that mediate OFQ-induced feeding. To further investigate this, we injected OFQ intracerebroventricularly and evaluated c-Fos immunoreactivity in brain areas thought to be involved in the regulation of food intake. Altered c-Fos expression as a consequence of OFQ injection was observed in the nucleus of the solitary tract, paraventricular nucleus of the hypothalamus, supraoptic nucleus, central nucleus of amygdala, lateral septal nucleus and lateral habenular nucleus. Presumably, OFQ modulates food ingestion through its action on these brain regions, most probably by activating feeding signals as well as suppressing satiety mechanisms.

Role of lipid type on morphine-stimulated diet selection in rats.

Administration of morphine is said to increase fat consumption among rats allowed to self-select nutrients. However, fats represent a diverse group of molecules, differing in metabolic and sensory properties. Despite this, lipid has yet to be manipulated as a variable in drug-stimulated nutrient selection studies. To determine whether lipid source can impact daily and morphine-stimulated (1, 3, and 10 mg/kg) diet intake, rats were provided with a choice between a high-fat and high-carbohydrate diet in three regimens in which the source of fat was varied between vegetable shortening, lard, or corn oil. Daily and morphine-stimulated diet selections were determined under all conditions. Under daily feeding conditions, rats ate more of the high-lipid diet compared with the high-carbohydrate diet when vegetable shortening or lard was the main lipid alternative, but lipid and carbohydrate intake did not differ when corn oil was the main lipid alternative. When rats were stimulated with morphine, the percentage of lipid increased relative to baseline intake only when the lipid diets were the preferred alternatives (i.e., vegetable shortening or lard). When preference between lipid and carbohydrate diets was neutral (i.e., corn oil condition), morphine did not enhance lipid consumption. These results indicate that morphine increases consumption of total energy or preferred diets and not lipid per se.

Discriminative stimulus effects of morphine: central versus peripheral training.

While it is well known that rats can discriminate a peripheral injection of morphine from a saline injection, to our knowledge no one has trained rats to discriminate a direct brain-site injection of morphine from saline. In the present series of studies, one group of rats was trained to discriminate morphine (0.3 microgram) from saline injected into the perifornical area of the hypothalamus (PFA), a process that took rats about 37 sessions to learn. A dose response generalization curve for PFA-injected morphine (0.01, 0.03, 0.1, and 0.17 microgram) was generated in which the two highest doses of morphine generalized to the morphine-appropriate training stimulus. Intraperitoneal (i.p.) injection of 3 mg/kg, but not 1 mg/kg morphine, resulted in morphine-appropriate responding in the PFA morphine-trained rats. A second group of rats was trained to discriminate i.p. injections of 3 mg/kg morphine from injections of saline. A dose-response generalization test for i.p.-injected morphine (0.3, 0.56, 1.0, and 1.7 mg/kg) was conducted in which the 0.17 mg/kg dose of morphine generalized to the morphine-appropriate training stimulus. Generalization tests using PFA-injected morphine doses (0.17, 0.56, 1.0, and 3.0 microgram) failed to result in morphine-appropriate responding in the i.p. morphine-trained rats. Naloxone administered into the PFA (50 microgram) or the periphery (3 mg/kg, i.p.) blocked morphine discrimination in the PFA-trained rats. However, when naloxone was injected into the PFA (50 microgram) together with i.p. morphine (3 mg/kg) in animals trained using i.p. injections, the antagonist failed to block morphine-appropriate responding. Thus, while peripheral injection of morphine generalized to the discriminative stimulus effects of morphine produced under PFA-injection training, the opposite effects were not noted.

Effects of the opioid antagonist naltrexone on feeding induced by DAMGO in the central nucleus of the amygdala and in the paraventricular nucleus in the rat.

The paraventricular nucleus of the hypothalamus (PVN) and the central nucleus of the amygdala (CNA) are two forebrain structures which are important in regulation of ingestive behavior. DAMGO is one of the most reliable and potent mu-selective opioid ligands that increases feeding in both of these brain nuclei. Administration of naloxone, an opioid antagonist, into the CNA prior to DAMGO blocks DAMGO-induced increases in food intake. The effect of this drug combination on food intake has not been evaluated in the PVN. However, intra-PVN injection of naloxone decreases deprivation and NPY-induced feeding. It has been suggested that CNA may modulate activity of midbrain and caudal brainstem centers via the hypothalamus. Based on these data, we evaluated whether an opioid-opioid interaction is present between the CNA and PVN which might affect feeding behavior. To test this, rats were doubly cannulated with 1 cannula placed in the PVN and 1 cannula in the CNA, allowing for co-administration of the opioid agonist into the PVN and the opioid antagonist into the CNA, and vice versa. CNA DAMGO increased feeding more than two-fold as compared to the vehicle-injected rats. When doses of 10, 12.5 and 25 micrograms of naltrexone (NTX) were injected into the PVN, CNA DAMGO no longer increased food intake above control levels. In the reverse situation, PVN DAMGO also increased food intake above control levels. However, when NTX was administrated unilaterally into the CNA at a relatively high dose (25 micrograms) or bilaterally (12.5 micrograms), PVN DAMGO-induced feeding was not altered. This suggests that an opioid-opioid signaling pathway exists from the CNA to the PVN which influences feeding via mu opioid receptors, whereas such a pathway from the PVN to the CNA does not seem to exist.

Intrahypothalamic discriminative stimulus effects of neuropeptide Y.

Neuropeptide Y (NPY) is one of the most ubiquitous neurotransmitters in the CNS and has been implicated in a variety of psychological and physiological functions. The current study investigated whether intrahypothalamic (I.H.) administrations of NPY were behaviorally discriminable from saline injections. Rats were trained to differentially respond based on whether they received I.H. injections of NPY (0.5 microg/0.5 microl) or saline (0.5 microl 0.9% NaCl). Subjects demonstrated discriminative control (85% correct in 8 out of 10 consecutive sessions) after a mean of 32 sessions. The ability of subjects to discriminate I.H. NPY from saline was dose dependent, with the lowest NPY dose tested (0.03 microg/0.5 microl) generalizing to saline. The opioid antagonist naloxone blocked the discrimination of NPY when administered I.P. (3.0 mg/kg) or I.H. (50 microg/0.5 microl).

Evidence for the presence of the platelet-activating factor receptor in the CFW mouse preimplantation two-cell-stage embryo.

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF), a potent signaling phospholipid, has a significant role in preimplantation embryo development. CFW mouse embryos respond to PAF with improved development and implantation rates. PAF's signal transduction mechanism in other cell types is receptor mediated. However, embryonic mRNA for the PAF receptor has not been detected. The study objectives were to determine the presence of PAF receptor mRNA in CFW mouse two-cell embryos by reverse transcription (RT)-polymerase chain reaction and Northern blot analysis and to ascertain the effect of PAF on intracellular calcium levels (a receptor-mediated event). Total RNA was purified by acid-phenol extraction and ethanol precipitation. Complementary DNA was synthesized by RT. RNA was primed with oligo-dT plus PAF receptor-specific primer (3' to 5') at 42 degrees C for 60 min, 95 degrees C for 10 min, and 5 degrees C for 5 min. The RT product was amplified with Taq polymerase and PAF receptor-specific primer (5' to 3') at 94 degrees C for 5 min and 54 degrees C for 5 min for one cycle, and at 72 degrees C for 3 min, 93 degrees C for 90 sec, and 61 degrees C for 150 sec for 30 cycles followed by 72 degrees C for 10 min and then holding at 4 degrees C. The product was analyzed by agarose gel electrophoresis, producing a single band (610 base pairs [bp]), thus demonstrating the presence of PAF-receptor mRNA. Sequence analysis of the cloned 610-bp fragment confirmed that it is the PAF receptor. Northern blot analysis also confirmed the expression of the PAF receptor in the CFW mouse preimplantation two-cell-stage embryo. PAF treatment of the two-cell-stage CFW mouse embryo resulted in a fourfold increase in intracellular calcium over background levels.

Palatability-induced hyperphagia increases hypothalamic Dynorphin peptide and mRNA levels.

Opioid involvement in regulating the intake of highly palatable diets was studied by examining the effect of feeding either a cornstarch-based diet (CHO) or a high fat diet containing sucrose (Fat/Sucrose) on hypothalamic opioid levels. Rats received either CHO ad libitum, Fat/Sucrose ad libitum, Fat/Sucrose pair-fed to the caloric intake of CHO, or Fat/Sucrose at 60% of ad libitum Fat/Sucrose intake. Animals receiving Fat/Sucrose ad libitum consumed more calories and gained more weight than animals receiving CHO (P < 0.001). Relative to CHO, ad libitum intake of Fat/Sucrose elevated proDynorphin mRNA levels in the arcuate and Dynorphin A1-17 levels in the paraventricular nucleus (PVN) (P < 0.05), but did not affect arcuate mRNA levels of proEnkephalin or proOpiomelanocortin (POMC), or PVN levels of Met-Enkephalin or beta-Endorphin. Pair-feeding the Fat/Sucrose diet to the level of intake of the CHO diet resulted in levels of proDynorphin and Dynorphin A1-17 that were similar in the two diet groups. Pair-feeding Fat/Sucrose reduced mRNA levels of proDynorpin, proEnkephalin and POMC, and Dynorphin A1-17 levels, relative to ad libitum feeding of Fat/Sucrose. Met-Enkephalin and beta-Endorphin were not affected by dietary treatment. Feeding Fat/Sucrose at 60% of ad libitum intake resulted in mRNA levels of proDynorphin, proEnkephalin and POMC, and Dynorphin A1-17 levels that were similar to those observed in CHO group. Hypothalamic Dynorphin A1-17 and proDynorphin mRNA levels are stimulated by feeding a highly palatable diet rich in fat and sucrose. The increased synthesis may be due in part to a palatability-induced overconsumption of calories. Caloric restriction of the same diet decreases mRNA levels of proDynorphin, proEnkephalin and POMC, as well as levels of Dynorphin A1-17.

Seasonal alteration in taste detection and recognition threshold in seasonal affective disorder: the proximate source of carbohydrate craving.

Increased appetite with associated carbohydrate craving are core symptoms of seasonal affective disorder (SAD) and have been attributed to decreased central serotonergic function. The proximate mechanisms for centrally mediated selective macronutrient consumption are unknown. We questioned whether seasonal alterations in taste sensation could serve as a mediator of dietary intake, as implied by the term 'craving'. Specifically, individuals who were seasonally depressed and reported carbohydrate craving would be more sensitive to gustatory cues associated with the presence of carbohydrate than nondepressed subjects. Taste detection and recognition thresholds for the four primary gustatory sensations--sweet, sour, salty, and bitter--were obtained in a group of 25 SAD patients and 23 non-psychiatric subjects during the winter, after 2 weeks of 10 000 lux morning and evening light treatment, and during the summer. Relative to the comparison group, the SAD group was less sensitive to sweet taste during the winter. Sweet taste threshold in the SAD group normalized during the summer; however, 2 weeks of light treatment failed to alter sweet detection thresholds in the SAD group. Moreover, within the SAD group, season exerted significant effects on sweet, sour, and bitter detection, but it did not influence salt-detection thresholds. The findings represent the first demonstration of specific changes in taste perception associated with the self-report of carbohydrate craving in SAD and are discussed in terms of the development of sweet craving and the serotonin hypothesis of SAD.

Rat hypothalamic NPY mRNA and brown fat uncoupling protein mRNA after high-carbohydrate or high-fat diets.

We measured the influence of diet composition on hypothalamic neuropeptide Y (NPY) message and brown fat uncoupling protein (UCP) mRNA using different diets. Sprague-Dawley rats ate ad libitum either chow, a high-carbohydrate (HC), an intermediate-carbohydrate (IHC), a high-fat (HF), or an intermediate-fat (IHF) diet, all with equal protein content (g/kcal). The HF and IHF groups ate less food mass and, except for HC, all groups consumed similar kilocalories during the study. After 1 wk, we killed the animals and extracted total RNA from arcuate nucleus, cortex, and brown adipose tissue (BAT). Arcuate NPY mRNA in the HF group was significantly (P < 0.001) lower than in the HC and chow group. There were no differences between groups in NPY message in cortex or NPY protein in the paraventricular nucleus. BAT UCP message levels were significantly higher (P = 0.001) in the HF group. Thus HF compared with HC and chow diet reduces expression of NPY mRNA in hypothalamic nuclei and increases expression of BAT UCP message.

Food systems: the relationship between health and food science/technology.

Changes in our understanding of diet and health drive changes in the way foods are processed. Conversely, what is available on the shelf will have an impact on the choices consumers make, thereby affecting their health. Historical examples of industrial manipulation of the diet include fortification and enrichment of cereal grains with vitamins; increased production of unsaturated vegetable oils and margarine as substitutions for hydrogenated fat, lard, and butter; lowered cholesterol content foods; reduced sugar content foods; lower sodium foods; decreased portion sizes or caloric density in prepackaged foods for use in weight loss or maintenance; and increased calcium levels to prevent osteoporosis. However, degenerative diseases such as cancer, atherosclerosis, bone disease, arthritis, and dementia will continue to be prevalent in the future. Whether or not the food systems available on the shelf can influence all of these disease states is not clear; however, studies have indicated that nutritional factors do contribute to the development of some of these diseases. Patterns in food consumption have changed and will continue to change as recommendations such as decreased consumption of saturated fats, salt, and cholesterol continue to be made. Increased ingestion of fish and/or fish oil is one recommendation that has been suggested because of the effect of omega-3 fatty acids on platelet aggregability and circulating levels of lipids. Wildly speculating from preliminary studies, fish oil has also been recommended for disease states including arthritis, cancer, and diseases of the immune system.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary fish oil on lung lipid profile and hypoxic pulmonary hypertension.

The effects of dietary polyunsaturated fats on chronic hypoxic pulmonary hypertension were assessed in rats fed fish oil, corn oil, or a lower fat, "high-carbohydrate" diet (regular) beginning 1 mo before the start of hypoxia (0.4 atm, n = 30 for each). Mean pulmonary arterial pressures were lower in the chronically hypoxic rats fed fish oil (19.7 +/- 1.8 mm Hg) than in the rats fed corn oil (25.3 +/- 1.6 mm Hg) or regular diets (27.5 +/- 1.5 mm Hg, P less than 0.05). The fish oil diet increased lung eicosapentaenoic acid 50-fold and depleted lung arachidonic acid 60% (P less than 0.0001 for each). Lung thromboxane B2 and 6-ketoprostaglandin F1 alpha levels were lower, and platelet aggregation, in response to collagen, was reduced in rats fed fish oil. Chronically hypoxic rats fed fish oil had lower mortality rates than the other hypoxic rats. They also had lower blood viscosity, as well as less right ventricular hypertrophy and less peripheral extension of vascular smooth muscle to intra-acinar pulmonary arteries (P less than 0.05 for each). The mechanism by which dietary fish oil decreases pulmonary hypertension and vascular remodeling during chronic hypoxia remains uncertain. The finding that a fish oil diet can reduce the hemodynamic and morphological sequelae of chronic hypoxia may have therapeutic significance.

Effect of bombesin and gastrin-releasing peptide on canine sphincter of Oddi.

This study reports the effects of bombesin and gastrin-releasing peptide (GRP) on the canine sphincter of Oddi using a method that allows repeated cannulation of the biliary sphincter in the unanesthetized animal through a Thomas cannula placed opposite the biliary papilla. Immediately after intravenous administration of bombesin or GRP, phasic sphincter contractions disappeared, basal sphincter pressures fell, and common bile duct pressures rose. Because bombesin releases cholecystokinin (CCK) and CCK resulted in a similar pattern to that of bombesin, the bombesin effect on the sphincter of Oddi may have been secondary to CCK's effect on the sphincter. To test if the bombesin effect on the sphincter of Oddi was due to the release of CCK, we blocked CCK release by administration of somatostatin, having first established that somatostatin blocked endogenous CCK release in our animal model by use of an intraduodenal infusion of lipid. Exogenous administration of bombesin failed to alter sphincter of Oddi or common bile duct pressures in dogs treated with somatostatin. Somatostatin did not, however, block CCK's effect on gallbladder contraction, since exogenous administration of CCK after somatostatin injection resulted in the pressure changes in the biliary tree typical of CCK-induced gallbladder contraction. Thus bombesin administration appears to result in sphincter relaxation and gallbladder contraction by the release of endogenous CCK rather than by a direct effect. The increase in common bile duct pressures was due to gallbladder contraction, since this rise in pressure was abolished by cholecystectomy. The peptide effect on sphincter contraction and basal sphincter pressure were unaffected by cholecystectomy.

Role of zinc supplementation in type II diabetes mellitus.

Zinc is required for normal immune function and taste acuity and enhances the in vitro effectiveness of insulin. Impaired immune function and taste have been reported in diabetic subjects, and decreased serum zinc levels and hyperzincuria occur in some diabetic subjects and animals. Subjects with type II diabetes were examined to determine whether the similar effects of zinc depletion and diabetes are causally related. Low serum zinc levels were found in 16 of 180 subjects (9 percent). There was no correlation between serum zinc and glycosylated hemoglobin levels. Natural killer cell activity did not differ between diabetic subjects (n = 28) and control subjects (n = 38) and did not correlate with serum zinc levels. T lymphocyte response to phytohemagglutinin was lower in diabetic subjects than in control subjects (70 +/- 10 versus 103 +/- 7 X 10(3) counts per minute) but was not lowest in those with the lowest zinc levels. Taste thresholds for hydrochloric acid, sucrose, sodium chloride, and urea were elevated in diabetic subjects (n = 28) versus control subjects (n = 10), but thresholds did not correlate with glycosylated hemoglobin or serum zinc levels. Zinc supplementation in nine diabetic subjects had no effect on the glycosylated hemoglobin level, natural killer cell activity, or taste thresholds, but it did increase mitogen activity in those with the lowest initial phytohemagglutinin responses. It is concluded that zinc deficiency occurs in a subset of subjects with type II diabetes but is not related to diabetes control and does not explain decreased taste acuity. Zinc deficiency may play a role in abnormal immune function in type II diabetes mellitus.

Opioid-induced feeding: localization of sensitive brain sites.

These experiments were designed to identify brain sites at which opioids might act to influence ingestive behavior and to determine which opioid receptor types are involved. After food deprivation, rats were given microinjections of naloxone into several brain regions and food intake was measured. Injections into or near the paraventricular (PVN) or ventromedial (VMH) hypothalamic nuclei or the globus pallidus (GP) reduced food intake; injections into the striatum or lateral hypothalamus (LH) were ineffective. A second study examined the ingestive effects of roughly equimolar doses (1.43-1.75 nmol) of dynorphin A (DYN), beta-endorphin (beta-END), and D-Ala2,D-Leu5-enkephalin (DADLE) when injected into 4 different brain regions. Only DYN significantly increased food intake, and this effect was seen only with injections into the PVN and VMH. Beta-END stimulated water intake when injected into the PVN, VMH and GP but not the LH. Further studies indicated that with PVN injections, DYN was effective at a dose as low as 0.47 nmol, and that a higher dose of DADLE (4.39 nmol) did stimulate food intake. These studies support an important role for dynorphin and the kappa opioid receptor in the regulation of feeding and suggest that the opioid regulation of food and water intake can be differentiated both by sites of action and by effective agonists.

Association between urinary zinc excretion and lymphocyte dysfunction in patients with lung cancer.

Patients with bronchogenic carcinoma often have low serum zinc concentrations and sometimes have markedly elevated renal zinc losses. Since normal zinc metabolism is critical for the proper function of T lymphocytes and natural killer cells, the effect of zinc status on T cell phytohemagglutinin response and peripheral blood lymphocyte natural killer cell activity was studied in patients with lung cancer. Mean (+/- SEM) serum zinc concentration in 75 patients with cancer was 67.4 +/- 2.2 micrograms/dl versus 96.0 +/- 8.0 micrograms/dl for normal subjects. Patients with low serum zinc levels (less than 70 micrograms/dl) had significantly higher urine zinc excretion than patients with normal serum zinc levels (1,385 +/- 240 micrograms per 24 hours versus 392 +/- 107 micrograms per 24 hours) (p less than 0.001). This pattern of zinc concentrations (i.e., low serum zinc in combination with high urine zinc) is typical of patients with mild zinc deficiency, and suggests that a mild chronic zinc deficiency state was present in some of these patients. When lymphocyte data were analyzed according to serum zinc concentrations and urinary zinc excretion, low serum zinc concentration and high urine zinc excretion both correlated with depressed T cell phytohemagglutinin response (p less than 0.005 and p less than 0.001, respectively). For instance, mean maximal phytohemagglutinin response in patients with urinary zinc excretion of more than 700 micrograms per 24 hours was 22,132 +/- 3,201 cpm (n = 14) compared with 68,130 +/- 6,850 cpm for patients with normal zinc excretion (n = 7). Peripheral blood lymphocyte natural killer cell activity did not correlate with either serum or urine zinc values. Oral zinc sulfate (220 mg, three times daily for six weeks) was then administered to patients with hyperzincuria (mean = 992 micrograms per 24 hours). Zinc-supplemented patients had normalization of T cell phytohemagglutinin response after zinc therapy, whereas control patients demonstrated continued T cell dysfunction. Natural killer cell activity did not change in either group during the study period. These data suggest that a mild subclinical zinc deficiency state may exist in some patients with lung cancer and may be an important cause of abnormal T cell function. Furthermore, zinc supplementation may be useful to improve lymphocyte function in selected patients. Whether zinc supplementation would alter the course of the disease or the patient's prognosis is presently unknown.

Do calories, osmolality, or calcium determine gastric emptying?

To determine whether calories, osmolality, or calcium mediate gastric emptying we employed a standardized radioactive meal in 10 normal human volunteers. A variety of simple and complex sugars, medium-chain fatty acid (MCFA), pectin, and gluten were dissolved in water and ingested with the test meal. The studies were also performed with calcium chloride, EDTA, and an equimolar combination of these chemicals. Results of gastric emptying showed that incremental glucose produced an increase in emptying time with a tendency for emptying time to show a proportionally greater delay with increasing glucose concentrations. Fructose and polyhexose had similar effects to glucose. Pentoses (xylose and arabanose) markedly prolonged gastric emptying when compared with the same amount of glucose. The effect of sucrose and gluten on gastric emptying did not significantly differ from controls. Twenty-five grams MCFA had an effect similar to 50 g glucose. Pectin, a complex carbohydrate, produced a varied effect in different individuals. There was no obvious relationship between osmolality and gastric emptying. Calcium chloride and EDTA prolonged gastric emptying, but the equimolar combination gave values similar to controls. Our findings suggest 1) calories nor osmolality alone determine gastric emptying, 2) both calcium and calcium chelation with EDTA prolong gastric emptying, and 3) a specific food does not necessarily produce the same effect on gastric emptying in different individuals.