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.

Evidence for a transcription-control region of Simian virus 40 in the adenovirus 2--Simian virus 40 hybrid, Ad2+ND 1

The complementary DNA strands of the nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid virus, Ad2(+)ND(1), were separated by isopycnic banding in a CsCl density gradient in the presence of synthetic polyribonucleotides. Separated strands were used in DNA-RNA hybridization reactions with RNA from cells productively infected by Ad2 or SV40, and with complementary SV40 RNA transcribed asymmetrically in vitro. About five times as much Ad2 RNA hybridized to the light stand of Ad2(+)ND(1) as to the heavy strand. Complementary RNA and early SV40 RNA (RNA synthesized before viral DNA replication) had significant homology only with the light strand. Only half as much of a preparation of RNA synthesized before and after viral DNA replication (early-plus-late SV40 RNA) hybridized to the light strand as to the heavy strand. These results indicate that templates for both late and early SV40 RNA are present in Ad2(+)ND(1). Therefore, the small SV40 segment within this virus (10-18% of the SV40 genome) must contain a transcription-control region. Ad2(+)ND(1) should thus be useful in the selective study of transcription as it occurs in cells infected by the oncogenic virus SV40.

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.

Implementation of a longitudinal mentored scholarly project: an approach at two medical schools

An increasing number of medical schools have implemented or are considering implementing scholarly activity programs as part of their undergraduate medical curricula. The goal of these programs is to foster students' analytical skills, enhance their self-directed learning and their oral and written communication skills, and ultimately to train better physicians. In this article, the authors describe the approach to implementing scholarly activities at a school that requires this activity and at a school where it is elective. Both programs have dealt with significant challenges including orienting students to a complex activity that is fundamentally different than traditional medical school courses and clerkships, helping both students and their mentors understand how to "stay on track" and complete work, especially during the third and fourth years, and educating students and mentors about the responsible conduct of research, especially involving human participants. Both schools have found the implementation process to be evolutionary, requiring experience before faculty could significantly improve processes. A required scholarly activity has highlighted the need for information technology (IT) support, including Web-based document storage and student updates, as well as automatic e-mails alerting supervisory individuals to student activity. Directors of the elective program have found difficulty with both ensuring uniform outcomes across different areas of study and leadership changes in a process that has been largely student-driven. Both programs have found that teamwork, regular meetings, and close communication have helped with implementation. Schools considering the establishment of a scholarly activity should consider these factors when designing programs.

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.

Refeeding, metabolic rate, and weight gain in anorexia nervosa: a review

Patients with anorexia nervosa require refeeding to restore normal body weight. A variety of studies have examined the role of metabolic rate in the refeeding of anorectic patients. Several measurement techniques have been used to divide metabolic rate into its components: basal metabolic rate, resting energy expenditure, activity-induced thermogenesis, and dietary-induced thermogenesis. In anorexia nervosa patients several consistent findings are present. First, the number of kilocalories required for weight gain or weight maintenance increases as weight increases. Second, over 50% of the body mass gained in anorectic individuals represents fat tissue. Finally, both a history of bulimic symptoms and a higher premorbid body weight may lead to lower calorie requirements. These findings suggest the need for gradual increase in calories provided throughout treatment; resting energy expenditures may aid the determination of caloric requirements

Effects of beta-chlornaltrexamine on food intake, body weight and opioid-induced feeding

beta-Chlornaltrexamine (beta-CNA) is a non-equilibrium opioid receptor antagonist which alkylates and inactivates opioid receptors. Because opioid peptides are thought to contribute to the regulation of food intake, we examined the effects of intracerebroventricular (icv) injections of beta-CNA on the food intake and body weight of male rats. We also tested the ability of beta-CNA to block food intake stimulated by selective agonists of kappa, mu and delta opioid receptors: dynorphin A2 (DYN), Tyr-D-Ala-Gly-(Me)Phe-Gly-ol (DAGO), and [(D-Ser2,Leu5]-enkephalin-Thr6 (DSLET). Treatment with beta-CNA caused a long-term (2-4 days) reduction in daily food intake and a concomitant reduction in body weight. An additional experiment indicated that the weight loss after beta-CNA treatment could be completely accounted for by the reduction in intake. beta-CNA treatment also abolished or greatly attenuated the feeding effects of DAGO, DSLET and DYN, even when these peptides were tested 26 hours after beta-CNA administration. The long duration of the effects of beta-CNA suggests that this compound will be a useful pharmacological tool in further study of the opioid feeding system.

Long-term second remissions in acute lymphatic leukemia

Long-term second remissions were seen in 5/66 patients with all. Relapse was extramedullary in 2/5. Persistent, progressive marrow lymphocytosis preceded relapse in 4/5 patients and persistent marrow eosinophilia in 1/5. All 5 patients had had an unmaintained remission of at least 6 months prior to relapse, and responded the second time to drugs which were essentially the same as those used initially. We conclude that long-term second remissions may occur in all. Patients who relapse after 6 months or more of unmaintained remission should be treated with the drugs used in current initial induction regimens in hope of cure.

The effect of cholecystokinin on food intake in gonadectomized and intact rats: the influence of sex hormones

Cholecystokinin (CCK) suppresses food intake in a number of animal models, but appears to be less effective in females [5,23]. We studied the effect of CCK on food intake in female rats on each day of the estrous cycle. In addition, we evaluated the effect of sex hormones on food intake in intact and castrate male rats which had been injected daily with oil or testosterone propionate + oil and ovariectomized female rats injected daily with oil, estradiol, progesterone or estradiol + progesterone. Food intake in intact, castrate and castrate + testosterone replaced male rats was decreased by CCK (5, 10 and 20 micrograms/kg) IP (p less than 0.05). Food intake was decreased by CCK (20 micrograms/kg) only during diestrous and metestrus in cycling female rats. During metestrus, a period of low estradiol in the presence of progesterone, food intake was also suppressed by CCK (5 and 10 micrograms/kg). CCK failed to decrease food intake in ovariectomized females receiving oil, estradiol and estradiol + progesterone. However, animals receiving progesterone alone responded to the high dose of CCK (20 micrograms/kg). Our data suggest that the effect of CCK on food intake in female rats may be dependent on the presence of progesterone. The lack of sensitivity to CCK during proestrus and estrus suggests that estradiol may be modulating the "permissive" action of progesterone on CCK's satiety effect.

Combined modality treatment of American Burkitt's lymphoma

Fifteen American patients with Burkitt's lymphoma were treated in a clinical trial employing chemotherapy, radiotherapy, and immunotherapy. Two patients died during induction, and 13 achieved complete responses. Eight patients relapsed at a median of 11 weeks from initial treatment, and seven of these have died. The remaining patient has enjoyed a prolonged third remission following intensive chemotherapy and bone marrow autograft. Five patients remain in their first remission in excess of 1 year. The major therapeutic goal in the management of Burkitt's lymphoma is the prevention of relapse; the identification of risk factors and various strategies to achieve this goal are discussed.

The effect of ovariectomy, estradiol and progesterone on opioid modulation of feeding

A number of lines of evidence have suggested that alterations in gonadal steroids may modulate opioid function. We report here the effects of manipulation of female gonadal steroids on the opioid feeding system. Naloxone produced a depression of feeding in all groups. Although the group X dosage interaction was not significant, an internally consistent tendency effect of naloxone among the different treatment groups was observed. Estradiol treated rats were 20 times less sensitive to naloxone's suppressive effects of feeding than ovariectomized animals. Sham operated controls and animals treated with estradiol and progesterone had sensitivities to naloxone which were intermediate to those seen in estradiol treated and ovariectomized animals. A significant drug X dosage interaction was present for the ketocyclazocine effects at 4 hours. Overall, ovariectomized animals were resistant to feeding induced by ketocyclazocine compared to the other groups. Ovariectomy significantly decreased ir-dynorphin levels in the cortex and these values were restored towards normal by a combination of estrogen and progesterone treatment. These studies add to the growing literature suggesting a role for the peripheral endocrine system in the modulation of opioid feeding system.

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.

Intermolecular cleavage by UmuD-like enzymes: identification of residues required for cleavage and substrate specificity

The UmuD-like proteins are best characterized for their role in damage-induced SOS mutagenesis. An essential step in this process is the enzymatic self-processing of the UmuD-like proteins. This reaction is thought to occur either via an intramolecular or intermolecular self-cleavage mechanism. Here, we demonstrate that it can also occur via an heterologous intermolecular cleavage reaction. The Escherichia coli UmuD enzyme demonstrated the broadest substrate specificity, cleaving both E. coli and Salmonella typhimurium UmuD substrates in vivo. In comparison, the wild-type S. typhimurium UmuD (UmuDSt) and MucA enzymes catalyzed intermolecular self-cleavage, but did not facilitate heterologous cleavage. Heterologous cleavage by the UmuDSt enzyme was, however, observed with chimeric UmuD substrates that possess residues 30-55 of UmuDSt. We have further localized the residue predominantly responsible for UmuDSt-catalyzed heterologous cleavage to Ser50 in the substrate molecule. We hypothesize that changes at this residue affect the positioning of the cleavage site of a substrate molecule within the catalytic cleft of the UmuDSt enzyme by affecting the formation of a so-called UmuD "filament-dimer". This hypothesis is further supported by the observation that mutations known to disrupt an E. coli UmuD' filament dimer also block intermolecular UmuDEc cleavage.

N-allylnormetazocine (SKF-10,047): the induction of feeding by a putative sigma agonist

Several distinct classes of opiate receptors have been postulated. It has been suggested that two of these, the kappa and sigma, may play a role in the initiation of feeding. The putative sigma receptor agonist N-allylnormetazocine increased food intake at doses of 0.1 and 1 mg/kg, whereas higher doses caused a decreased intake under some conditions. This stimulatory effect increased after repeated injections and was naloxone reversible. After repeated injections of N-allylnormetazocine, the feeding response to ketocyclazocine, but not morphine, appeared at an earlier point than in naive rats. These experiments support the suggestion that the sigma receptor may play some role in the initiation of feeding.

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.

Severe zinc deficiency presenting with acrodermatitis during hyperalimentation: diagnosis, pathogenesis, and treatment

Seven patients developed severe zinc deficiency with acrodermatitis during hyperalimentation. Several of them had other problems such as diarrhea, poor wound healing and mental changes, which may also have been related to zinc deficiency. Three patients were on hyperalimentation for 2 weeks or less when skin lesions first developed, and most patients were receiving regular infusions of plasma. All patients responded to enteral administration of zinc. We conclude that: 1) severe zinc deficiency with acrodermatitis is not a rare complication of hyperalimentation; 2) even short-term hypralimentation may be complicated by severe zinc deficiency with acrodermatitis; 3) plasma is not an appropriate way to provide zinc supplementation; 4) if intravenous zinc preparations are not available, oral supplementation is usually effective; and 5) all patients undergoing hyperalimentation should receive zinc supplementation and have regular monitoring of their serum zinc level.

Effects of neuropeptide Y on short-term memory

Neuropeptide Y (NPY) is a ubiquitous neuropeptide which may modulate several behavioral and physiological phenomena. Among other behavioral effects, NPY has been shown to enhance memory processes in mice. The current study employed a delayed conditional discrimination procedure to evaluate the effects of intracerebroventricular injections of NPY on short-term working memory. This conditional discrimination procedure assesses appropriate responding, based on a previously presented stimulus, after various delays have been imposed between the stimulus and the opportunity for a response. Delay values ranged from 0.01 s to 30 s. NPY decreased accuracy across delay values in a dose-dependent manner. The two highest doses of NPY (3.0 and 10.0 micrograms) significantly decreased accuracy. Doses lower than those used in the current study have shown facilitation of memory processes under avoidance procedures in mice. Intraperitoneal naloxone (3.0 mg/kg), an opioid antagonist, completely blocked NPY's memory degrading effects. Procedural differences may account for NPY-induced degradation of short-term working memory under delayed conditional discrimination and previous reports of NPY's enhancement of retention under shock avoidance procedures.

Naloxone's effect on meal microstructure of sucrose and cornstarch diets

The opioid receptor antagonist naloxone decreases consumption of high-sucrose diets but does not reduce cornstarch diet intake in energy-restricted rats. Sucrose-fed rats eat at a much higher rate, consuming more food than cornstarch-fed rats. We examined meal microstructure using an automated weighing system in food-restricted rats eating either a high-sucrose or high-cornstarch diet. Sucrose-fed rats exhibited a higher rate of eating during their first meal compared with cornstarch-fed rats (0.34 vs. 0.20 g/min, respectively). However, naloxone did not reduce eating rate in either group. Naloxone decreased the size of the first meal in both diet groups by shortening the length of the meal. Naloxone's anorectic effect was more potent in the sucrose-fed rats. These results indicate that naloxone's heightened anorectic effect on sucrose diet consumption is not "rate dependent." Naloxone's anorectic actions may be modulated by two conditions, the sensory properties of food and the energy state of the animal. Thus the elevated anorectic potency of naloxone in energy-restricted sucrose-fed rats may reflect actions on neural systems that mediate orosensory and/or postingestive signals.

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.

Mutational specificity of benzo[a]pyrene diolepoxide in monkey cells

Benzo[a]pyrene diolepoxide (BPDE) is thought to be the major mutagenic and carcinogenic intermediate in benzo[a]pyrene metabolism in mammalian cells. In order to test the mutagenic specificity of this compound in mammalian cells, we have used the pZ189 shuttle vector system to identify and analyze point mutations induced when DNA treated in vitro with BPDE is replicated in monkey cells. We find that point mutations occur almost exclusively at G.C base pairs; G.C----T.A and G.C----C.G transversions and single base pair deletions occur most frequently. This pattern is consistent with the known preferential covalent binding of BPDE to G residues.

Children with serious illness: behavioral correlates of separation and isolation

The deleterious effects of separation have been demonstrated in experimental animal studies and in naturalistic case studies of children. In this study extensive observational and physiological records were obtained on four preschool children who were receiving chemotherapy for childhood cancer. The findings generally parallel those reported in the subhuman primate literature. The children's behavior followed a sequence of agitation followed by behavioral depression. The findings underscore the seriousness of parent-child separation and the need to develop intervention strategies to ameliorate these deleterious effects.