[D-Trp(34)] neuropeptide Y is a potent and selective neuropeptide Y Y(5) receptor agonist with dramatic effects on food intake.

The neuropeptide Y (NPY) Y(5) receptor has been proposed to mediate several physiological effects of NPY, including the potent orexigenic activity of the peptide. However, the lack of selective NPY Y(5) receptor ligands limits the characterization of the physiological roles of this receptor. Screening of several analogs of NPY revealed that [D-Trp(34)]NPY is a potent and selective NPY Y(5) receptor agonist. Unlike the prototype selective NPY Y(5) receptor agonist [D-Trp(32)]NPY, [D-Trp(34)]NPY markedly increases food intake in rats, an effect that is blocked by the selective NPY Y(5) receptor antagonist CGP 71683A. These data demonstrate that [D-Trp(34)]NPY is a useful tool for studies aimed at determining the physiological roles of the NPY Y(5) receptor.

Activation of the NPY Y5 receptor regulates both feeding and energy expenditure.

Intracerebroventricular (ICV) administration of neuropeptide Y (NPY) has been shown to decrease energy expenditure, induce hypothermia, and stimulate food intake. Recent evidence has suggested that the Y5 receptor may be a significant mediator of NPY-stimulated feeding. The present study attempts to further characterize the role of NPY Y5-receptor subtypes in feeding and energy expenditure regulation. Satiated Long-Evans rats with temperature transponders implanted in the interscapular brown adipose tissue (BAT) displayed a dose-dependent decrease in BAT temperature and an increase in food intake after ICV infusion of NPY. Similar effects were induced by ICV administration of peptide analogs of NPY that activate the Y5 receptor, but not by analogs that activate Y1, Y2, or Y4 receptors. Furthermore, ICV infusion of the Y5 selective agonist D-[Trp(32)]-NPY significantly reduced oxygen consumption and energy expenditure of rats as measured by indirect calorimetry. These data suggest that the NPY Y5-receptor subtype not only mediates the feeding response of NPY but also contributes to brown fat temperature and energy expenditure regulation.

GR231118 (1229U91) and other analogues of the C-terminus of neuropeptide Y are potent neuropeptide Y Y1 receptor antagonists and neuropeptide Y Y4 receptor agonists.

GR231118, BW1911U90, Bis(31/31')[[Cys31, Trp32, Nva34] neuropeptide Y(31-36)] (T-190) and [Trp-Arg-Nva-Arg-Tyr]2-NH2 (T-241) are peptide analogs of the C-terminus of neuropeptide Y that have recently been shown to be antagonists of the neuropeptide Y Y1 receptor. In this study, the activity of these peptides at each of the cloned neuropeptide Y receptor subtypes is determined in radioligand binding assays and in functional assays (inhibition of forskolin-stimulated cAMP formation). GR231118 is a potent antagonist at the human and rat neuropeptide Y Y1 receptors (pA2 = 10.5 and 10.0, respectively; pKi = 10.2 and 10.4, respectively), a potent agonist at the human neuropeptide Y Y4 receptor (pEC50 = 8.6; pKi = 9.6) and a weak agonist at the human and rat neuropeptide Y Y2 and Y5 receptors. GR231118 also has high affinity for the mouse neuropeptide Y Y6 receptor (pKi = 8.8). Therefore, GR231118 is a relatively selective neuropeptide Y Y1 receptor antagonist, but has appreciable activity at the neuropeptide Y Y4 and Y6 receptors as well. BW1911U90, T-190 and T-241 are moderately potent neuropeptide Y Y1 receptor antagonists (pA2 = 7.1, 5.8 and 6.5, respectively; pKi = 8.3, 6.5 and 6.8, respectively) and neuropeptide Y Y4 receptor agonists (pEC50 = 6.8, 6.3 and 6.6, respectively; pKi; 8.3, 7.7 and 8.3, respectively). These data suggest that the C-terminus of neuropeptide Y and related peptides is sufficient for activation of the neuropeptide Y Y4 receptor, but is not sufficient for activation of the neuropeptide Y Y1 receptor. Because BW1911U90, T-190 and T-241 are significantly less potent at the cloned human neuropeptide Y Y1 receptor than at the neuropeptide Y receptor in human erythroleukemia cells, these cells may express a novel neuropeptide Y receptor with high affinity for these peptides.

Amides of piperidine, morpholine and piperazine substituted 1-phenylethylamines: inhibitors of acylCoA:cholesterol acyltransferase (ACAT) activity in vitro and in vivo.

Amides of some substituted 1,2-diarylethylamines have been shown to exhibit potent acylCoA:cholesterol acyltransferase (ACAT, EC 2.3.1.26) inhibitory activity in vitro in microsomal ACAT assays but show poor in vivo activity in a cholesterol-fed hamster model. In an effort to design ACAT inhibitors that are potent in both our in vitro and in vivo assays a series of amides of piperidine, morpholine and piperazine substituted 1-phenylethylamines were synthesized. Compounds of this series were found to be very potent inhibitors of ACAT in a microsomal ACAT assay and also exhibited potent activity in a cholesterol-fed hamster model.

Hypocholesterolemic activity of a novel inhibitor of cholesterol absorption, SCH 48461.

The amount of cholesterol that circulates in the plasma as lipoproteins can be affected by the balance of cholesterol metabolism within and between the intestines and liver. In the present report, we describe a novel hypocholesterolemic agent and document its pharmacological effects in animal models of hypercholesterolemia. The oral administration of (3R,4S)-1,4-bis-(4-methoxyphenyl)-3-(3-phenylpropyl)-2-azetidinone (SCH 48461) reduced plasma cholesterol concentrations in cholesterol-fed hamsters, rats and rhesus monkeys with ED50s of 1, 2 and 0.2 mg/kg per day, respectively, SCH 48461 was also highly effective in reducing hepatic cholesteryl ester accumulation in cholesterol-fed hamsters and rats after 7 days of treatment. In one 3 week study, rhesus monkeys were fed a 0.25% cholesterol/22% saturated fat diet with or without SCH 48461. At the end of the 3 week period the control group's VLDL + LDL-cholesterol increased to 180 Mg/dl from a baseline of approximately 65 mg/dl while plasma apolipoprotein B levels had doubled. Animals treated daily with 1 mg/kg SCH 48461 maintained their baseline levels of VLDL + LDL-cholesterol, HDL-cholesterol, and plasma apolipoproteins B and A-I. After 3 weeks the diets of the two groups were switched. Within 1 week SCH 48461 (1 mg/kg per day) rapidly reversed the elevated VLDL + LDL-cholesterol levels of the previous control group to near baseline values. SCH 48461 exerted its hypocholesterolemic effect through the inhibition of cholesterol absorption. A dose of 10 mg/kg per day inhibited cholesterol absorption in cholesterol-fed hamsters by 68% while a similar reduction was achieved in chow-fed monkeys with 3 mg/kg per day. This latter dose inhibited cholesterol absorption in cholesterol-fed monkeys by 95%. Treatment of cholesterol-fed monkeys with 10 mg/kg per day SCH 48461 significantly increased fecal neutral sterol excretion (52 vs. 32 mg/kg) but had no effect on acidic sterol excretion. Using a 2-h absorption model in cholesterol-fed hamsters, SCH 48461 caused a 46% inhibition of unesterified [14C]cholesterol accumulation in the intestinal wall and a 90% inhibition of cholesteryl ester formation at a dose of 10 mg/kg. Similar data were observed when the plasma radioactivity was assessed, indicating inhibition of both free (61%) and esterified (85%) cholesterol appearance. In contrast, CI-976, a potent acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, did not affect the uptake of free cholesterol into the intestines while inhibiting cholesterol esterification (98% inhibition).(ABSTRACT TRUNCATED AT 400 WORDS)

Congenital tracheoesophageal fistula associated with carcinoma of the lung in an adult.

A rare case of adult congenital H-type tracheoesophageal fistula was diagnosed. Subsequently, at operation, large cell, undifferentiated carcinoma of the right middle lobe with extension to the right lobe and adherence to the diaphragm was documented. The diagnosis, surgical intervention, and 4-year follow-up are presented.

Fibronectin stimulates macrophage uptake of low density lipoprotein-heparin-collagen complexes.

In this study, we investigated whether fibronectin will enhance macrophage uptake of particulate complexes of low density lipoproteins (LDL), heparin, and fibrillar collagen and whether fibronectin's opsonic effect could be modulated by the heparin component in these model matrices. We isolated a heparin fraction (HepFn) based on its affinity to fibronectin. HepFn appeared more charged than unfractionated heparin, as evidenced by enhanced electrophoretic mobility and ability to effect a cathodic shift in the electrophoretic migration of fibronectin. HepFn lacked the smaller molecular weight species present in unfractionated heparin. Macrophage endocytosis of LDL-heparin-collagen complexes, as evidenced by the intracellular accumulation of LDL-derived cholesteryl esters and endogenously synthesized cholesteryl esters, was enhanced by fibronectin. When LDL matrix complexes were prepared with HepFn, fibronectin's opsonic properties were significantly enhanced. F(ab)2 fragments of anti-fibronectin, capable of inhibiting fibronectin's opsonization of gelatin-derivatized latex particles, inhibited the fibronectin-dependent stimulation of cholesteryl ester synthesis by macrophages exposed to LDL-HepFn-collagen complexes. Thus, fibronectin stimulates macrophage endocytosis of LDL matrix complexes. The affinity of the constituent glycosaminoglycan for fibronectin is important in the regulation of this phenomenon.

Insoluble low-density lipoprotein-proteoglycan complexes enhance cholesteryl ester accumulation in macrophages.

The interaction of arterial proteoglycans (PGs) and low-density lipoproteins (LDLs) has been postulated to be an important factor in extracellular cholesterol accumulation in the arterial wall. In the present study, insoluble complexes of LDL and PG (LDL-PG) were prepared and their effects on cholesteryl ester accumulation in mouse peritoneal macrophages was tested. The cholesteryl ester content of macrophages incubated with LDL-PG for 3 days was greater than 20 times that observed in cells incubated with LDL alone. The uptake of 125I-LDL by macrophages was markedly stimulated if LDL was incorporated into a complex with PG. However, in contrast to either LDL or acetylated LDL (ALDL), the extent of subsequent degradation of LDL-PG by the cells was reduced. The uptake and degradation of LDL-PG complexes stimulated macrophage incorporation of 14C-oleic acid into cholesteryl oleate 4- to 5-fold over LDL alone; however, esterification was significantly less than that observed with ALDL, even though more LDL-PG was degraded. Ultrastructurally, macrophages incubated with LDL-PG complexes contained lipid droplets as well as numerous phagocytic vacuoles often containing material similar in appearance to insoluble complexes. These results demonstrate that components of the extracellular matrix, such as PG, can modify the catabolism of LDL by scavenger cells. This phenomenon may be potentially important with respect to foam-cell genesis from macrophages in the arterial wall.

Altered glycosaminoglycan metabolism in injured arterial wall.

Glycosaminoglycans (GAG) are believed to be important in the pathogenesis of atherosclerosis. We have previously demonstrated that areas of injured aorta that have been re-endothelialized accumulate increased amounts of lipid and GAG when compared to areas remaining de-endothelialized. We have now examined the net incorporation of labeled precursors into the individual GAG present in both re-endothelialized and de-endothelialized areas of rabbit aorta. Aortic tissue was examined at 2-3 and 10-14 weeks after a denuding injury by incubating tissue minces with [3H]glucosamine and sodium [35S]sulfate for 24 hr. Following incubation, the aortic GAG were isolated and assayed for uronic acid concentration and radioactivity. Results indicate that the total GAG concentration was significantly greater (P less than 0.001) in the re-endothelialized (9.46 +/- 0.29 micrograms/mg lipid-free dry residues (LFDR), mean +/- SE) as compared to de-endothelialized (7.89 +/- 0.43 micrograms/mg LFDR) areas. The concentration in uninjured aorta was 9.01 +/- 0.69. The difference between the injured tissues was attributable to increased concentrations of sulfated GAG. Hyaluronic acid and chondroitin sulfate were the most metabolically active of the GAG in either uninjured or injured aorta, together accounting for over 75% of the 3H label. The 3H specific radioactivities of the four GAG in the short-term, re-endothelialized subgroup were all increased nearly twice that found in uninjured and de-endothelialized tissues. With the exception of heparan sulfate, no significant differences were noted in the 3H specific radioactivities between the re-endothelialized and de-endothelialized areas in the long-term subgroup. These results indicate that, relative to adjacent areas of de-endothelialization, GAG preferentially accumulate in re-endothelialized areas even as early as 2-3 weeks following a denuding injury. Overall, metabolic data suggest that increased synthesis is responsible for this effect, although the net contribution of degradative processes cannot be overlooked since GAG turnover was not specifically examined. Thus, it is possible that regenerated endothelium may modify the GAG metabolism of the arterial wall following arterial injury.

Isolation and preliminary characterization of proteoglycans dissociatively extracted from human aorta.

Aortic proteoglycans (PG) were isolated from human aorta intima-media preparations with 4 M guanidine hydrochloride in the presence of protease inhibitors. The extracted PG mixture comprised 67% of the total aortic PG and was composed of 65% chondroitin sulfate, 22% dermatan sulfate, 8% heparan sulfate, and 4% hyaluronate. Attempts at isolation and purification of PG monomers using isopycnic CsCl gradient centrifugation under associative and dissociative conditions resulted in appreciable loss of PG through associations with co-extracted aortic proteins. The addition of a gel chromatographic step on Sepharose CL-4B under dissociative conditions resulted in separation of PG from the majority of co-extracted proteins. In addition, the procedure resulted in a separation of the PG into a population (PG-I) eluting near the column V0 and one (PG-II) included with a Kav of 0.38. Hyaluronic acid co-eluted with PG-I. The major glycosaminoglycan in PG-I was chondroitin sulfate, (85 to 95%). No dermatan sulfate was detected in PG-I, but this glycosaminoglycan was the predominant glycosaminoglycan in PG-II (50 to 70%). Heparan sulfate was present in small amounts in both PG-I and PG-II. Data presented support the proposal of at least three species of PG monomers in the aortic wall. Chromatographic studies under dissociative and associative conditions indicated that PG comprising PG-I but not PG-II were capable of associations with hyaluronic acid.

Aortic total glycosaminoglycan and dermatan sulfate changes in atherosclerotic rhesus monkeys.

The composition and content of aortic glycosaminoglycans were studied in groups of rhesus monkeys fed control or atherogenic diets for 9 or 19 months. Aortic uronic acid content was significantly increased in both groups of monkeys with atherosclerosis. The major glycosaminoglycan in both control and atherosclerotic aortas was chondroitin sulfate with lesser amounts of heparan sulfate, dermatan sulfate, and hyaluronic acid. Dermatan sulfate was the only glycosaminoglycan to show a statistically significant elevation (65 to 87 per cent) in animals fed the atherogenic diet. This increase was positively correlated with the increased accumulation of aortic cholesterol (r = 0.4709, p less than 0.05). The results indicate that dermatan sulfate may be the major glycosaminoglycan involved during the early events of atherogenesis perhaps through retention of lipoprotein in the atherosclerotic artery.

Effect of fiberoptic bronchoscopy on respiratory performance in patients with chronic airways obstruction.

Lung volumes, airway resistance, expiratory flow rates, distribution of ventilation, and arterial blood gases were measured before and after fiberoptic bronchoscopy in 13 patients with moderately severe chronic airways obstruction and in 10 healthy non-smoking controls. Arterial blood gases were also monitored serially during the procedure. Arterial oxygen tension (Pao2) fell during fiberoptic bronchoscopy in both patients and controls whereas arterial carbon dioxide tension and pH remained unchanged. Control subjects had no change in lung mechanics after fiberoptic bronchoscopy. However, the patients consistently developed increased airway obstruction after fiberoptic bronchoscopy. Within 24 hours after bronchoscopy lung function in the patients returned to baseline values, except for the residual volume which remained abnormally high. The topical application of lignocaine (Lidocaine) for local anesthesia before fiberoptic bronchoscopy produced no effect on lung mechanics in nine patients and 10 controls, but Pao2 decreased in both the patient and control groups. These results indicate that fiberoptic bronchoscopy consistently inpairs lung mechanics and gas exchange in patients with chronic airways obstruction but that the impairment is mild and reversible. Lignocaine administration as well as the intubation procedure contribute to the fall in Pao2 which occurs both in the patients and in subjects without pre-existing lung disease.

Effect of liver failure on the response of ventilation and cerebral criculation to carbon dioxide in man and in the goat.

1. The acid-base state of arterial blood and cerebrospinal fluid, and the ventilatory response to CO2, were measured in twelve patients with liver disease. The CO2 response was also measured in eight goats before and after the experimental production of liver failure. Arterial PCO2 and pH, cerebral blood flow and the cerebral metabolic rate for oxygen were also measured in four of the goats while they breathed air and various CO2-enriched gas mixtures. 2. Liver failure was accompanied by a respiratory alkalosis in both the patients and in the goats. Decreased PCO2 and increased pH occurred in the cerebrospinal fluid and in the arterial blood of the patients. 3. The slope of the ventilatory response to CO2 was reduced when liver failure was severe, in patients and goats alike. In addition there was a reduction in the extrapolated PCO2 at zero ventilation, even when liver failure was mild. 4. Cerebral blood flow and metabolic rate were consistently reduced in the goats during liver failure. There was also less cerebral vasodilatation and a greater reduction in cerebral metabolism during experimental hypercapnia when these animals were in liver failure. 5. The decreases in the ventilatory and cerebral circulatory responsiveness to CO2 indicate that the brain is less well defended against hypercapnia in liver failure, and these changes are especially unfavourable as cerebral function deteriorates when the PCO2 is increased.