Factors influencing the quality of Myrmecia pilosula (Jack Jumper) ant venom for use in in vitro and in vivo diagnoses of allergen sensitization and in allergen immunotherapy.

BACKGROUND: Allergen immunotherapy uses pharmaceutical preparations derived from naturally occurring source materials, which contain water-soluble allergenic components responsible for allergic reactions. The success of in vivo and in vitro diagnoses in allergen sensitization and allergen immunotherapy largely depends on the quality, composition and uniformity of allergenic materials used to produce the active ingredients, and the formulation employed to prepare finished products. OBJECTIVES: We aimed to examine the factors influencing batch-to-batch consistency of Jack Jumper (Myrmecia pilosula) ant venom (JJAV) in the form of active pharmaceutical ingredient (AI) and informed whether factors such as temperature, artificial light and container materials influence the quality of JJAV AIs. We also aimed to establish handling and storage requirements of JJAV AIs to ensure preservation of allergenic activities during usage in the diagnosis of allergen sensitization and in allergen immunotherapy. METHODS: The quality and consistency of JJAV AIs were analysed using a combination of bicinchoninic acid assay for total protein quantification, HPLC-UV for JJAV allergen peptides quantification, ELISA inhibition for total allergenic potency, SDS-PAGE, AU-PAGE and immunoblot for qualitative assessment of JJAV components, and Limulus Amebocyte Lysate assay for the quantification of endotoxin concentration. API-ZYM and Zymogram assays were used to probe the presence of enzymatic activities in JJAV. RESULTS: Pharmaceutical-grade JJAV for allergen immunotherapy has good batch-to-batch consistency. Temporary storage at 4°C and light exposure do not affect the quality of JJAV. Exposure to temperature above 40°C degrades high MW allergens in JJAV. Vials containing JJAV must be stored frozen and in upright position during long-term storage. CONCLUSIONS AND CLINICAL RELEVANCE: We have identified factors, which can influence the quality and consistency of JJAV AIs, and provided a framework for appropriate handling, transporting and storage of JJAV to be used for the diagnosis of allergen sensitization and in AIT.

The life cycle of Huffmanela huffmani Moravec, 1987(Nematoda: Trichosomoididae), an endemic marine-relict parasite of Centrarchidae from a Central Texas spring.

The life cycle of the swim bladder nematode Huffmanela huffmani Moravec, 1987 (Trichinelloidea: Trichosomoididae), an endemic parasite of centrarchid fishes in the upper spring run of the San Marcos River in Hays County, Texas, USA, was experimentally completed. The amphipods Hyalella cf. azteca (Saussure), Hyalella sp. and Gammarus sp. were successfully infected with larvated eggs of Huffmanela huffmani. After ingestion of eggs of H. huffmani by experimental amphipods, the first-stage larvae hatch from their eggshells and penetrate through the digestive tract to the hemocoel of the amphipod. Within about 5 days in the hemocoel of the experimental amphipods at 22 °C, the larvae presumably attained the second larval stage and were infective for the experimental centrarchid definitive hosts, Lepomis spp. The minimum incubation period before adult nematodes began laying eggs in the swim bladders of the definitive hosts was found to be about 7.5 months at 22 °C. This is the first experimentally completed life cycle within the Huffmanelinae.

Standardized standing pelvis-to-floor photographs for the assessment of lower-extremity alignment.

OBJECTIVES: The objective of this cross-sectional study was to assess the intra-rater, inter-rater and test-retest reliability and concurrent validity of lower-extremity alignment estimated from a photograph [photographic alignment (PA) angle]. METHODS: A convenience sample of participants was recruited from the community. Radiopaque stickers were placed over participants' anterior superior iliac spines. One radiograph and one photograph were taken with the participant standing in a standardized position. The stickers were removed. After 30 min they were reapplied and a second photograph was taken. The hip-knee-ankle (HKA) angle was measured from each radiograph using customized imaging analysis software. The same software was used by three readers to measure the PA angle from each photograph from the first set twice, at least 2 weeks apart. One reader measured the PA angle from the second set of photographs. Reliability was tested using intraclass correlation coefficients (ICC(2,1)), Bland-Altman analyses and the minimal detectable change (MDC95). Concurrent validity was tested using a Pearson's correlation coefficient and Bland-Altman analysis. RESULTS: Fifty adults participated (mean age 41.8 years; mean body mass index 24.7 kg/m(2)). The PA angle was 4.5° more varus than the HKA angle; these measures were highly correlated (r = 0.92). Intra-rater (ICC(2,1) > 0.985), inter-rater (ICC(2,1) = 0.988) and test-retest reliability (ICC(2,1) = 0.903) showed negligible bias (<0.20°). The MDC95 was 2.69°. CONCLUSIONS: The PA angle may be used in place of the HKA angle if a bias of 4.5° is added. A difference of 3° between baseline and follow-up would be considered a true difference.

Validity and sensitivity to change of three scales for the radiographic assessment of knee osteoarthritis using images from the Multicenter Osteoarthritis Study (MOST).

OBJECTIVES: The purpose of this study was to assess the concurrent validity and sensitivity to change of three knee osteoarthritis (OA) grading scales. The Kellgren-Lawrence (KL) and the Osteoarthritis Research Society International (OARSI) joint space narrowing (JSN) grading scales are well-established. The third scale, the compartmental grading scale for OA (CG) is a novel scale which grades JSN, femoral osteophytes, tibial erosion and subluxation to create a total score. METHODS: One sample of 72 posteroanterior (PA) fixed-flexion radiographs displaying mild to moderate knee OA was selected from the Multicenter Osteoarthritis Study (MOST) to study validity. A second sample of 75 radiograph pairs, which showed an increase in OA severity over 30 months, was selected to study sensitivity to change. The three radiographic grading scales were applied to each radiograph in both samples. Spearman's rank correlation coefficients were used to correlate the radiographic grades and the change in grades over 30 months with a Whole-organ Magnetic Resonance Imaging Score (WORMS)-based composite score which included five articular features of knee OA. RESULTS: Correlations between the KL, OARSI JSN and CG grading scales and the magnetic resonance image (MRI)-based score were 0.836, 0.840 and 0.773 (P < 0.0001) respectively while correlations between change in the radiographic grading scales and change in the MRI-based score were 0.501, 0.525 and 0.492 (P < 0.0001). CONCLUSIONS: All three radiographic grading scales showed high validity and are suitable to assess knee OA severity. They showed moderate sensitivity to change; therefore caution should be taken when using ordinal radiographic grading scales to monitor knee OA over time.

Getting depression clinical practice guidelines right: time for change?

OBJECTIVE: As part of a series of papers ['Chronobiology of mood disorders' Malhi & Kuiper. Acta Psychiatr Scand 2013;128(Suppl. 444):2-15; and 'It's time we managed depression: The emerging role of chronobiology' Malhi et al. Acta Psychiatr Scand 2013;128(Suppl. 444):1] examining chronobiology in the context of depression, this article examines recent western clinical practice guidelines (CPGs) for the treatment of depression with respect to the recommendations they make, in particular as regards chronobiological treatments, and briefly considers the implications of their methodology and approach. METHOD: Five international treatment guidelines, which had been published in the past 5 years, were identified, representing North American and European views. Chosen guidelines were reviewed by the authors, and the relevant recommendations were distributed for discussion and subsequent synthesis. RESULTS: Most current guidelines do not address chronobiology in detail. Chronotherapeutic recommendations are tentative, although agomelatine is considered as an option for major depression and bright light therapy for seasonal affective disorder. Sleep deprivation is not routinely recommended. CONCLUSION: Recommendations are limited by the lack of reliable therapeutic markers for chronotherapeutics. Current evidence supports use of light therapy in seasonal depression, but in non-seasonal depression there is insufficient evidence to support reliance on chronotherapeutics over existing treatment modalities.

Shared Individual Formulation Therapy (SIFT): an open-label trial of a new therapy accommodating patient heterogeneity in functional neurological disorder.

BACKGROUND: Functional Neurological Disorder (FND) is a complex neuropsychiatric condition with a multifactorial aetiology. The heterogeneity of patients with FND is rarely considered in psychotherapy trials, which may contribute to variable outcomes. Shared Individual Formulation Therapy (SIFT) is a new, brief (four session) psychotherapy that aims to accommodate heterogeneity by providing a personalised, trans-theoretical formulation of the person's difficulties and accompanying management plan. METHODS: An open-label, prospective trial of outpatient SIFT for adults with FND was conducted, using health-related quality of life (SF-12) as the principal outcome measure, with secondary measures of mental health, dissociation, health care use and attitude to the FND diagnosis. Measures were collected at baseline, end of treatment and 6- and 12-month follow-ups. RESULTS: Twenty-nine participants with various FND symptoms enrolled. Twenty-four completed all four sessions and 25 completed follow-up measures at 12 months. SF-12 scores improved significantly at end of treatment and were sustained throughout follow-up with moderate effect sizes (0.39-0.47; all p < 0.001). Most secondary outcomes also improved significantly at all time points. The intervention was highly acceptable and tolerable to patients and perceived as beneficial. CONCLUSION: This trial provides preliminary evidence for initial and sustained benefit from SIFT for adults with FND. Further study is needed to validate these findings.

Chronic tobacco smoking and neuropsychological impairments: A systematic review and meta-analysis.

The link between neuropsychological impairments and chronic tobacco smoking is not clear and in the current literature there is a lack of robust analyses investigating this association. A systematic review of the literature was conducted in order to identify relevant longitudinal and cross-sectional studies conducted from 1946 to 2017. A meta-analysis was performed from 24 studies testing the performance of chronic tobacco smokers compared with non-smokers on neuropsychological tests related to eight different neuropsychological domains. The results revealed a cross-sectional association between neuropsychological impairments and chronic tobacco smoking in cognitive impulsivity, non-planning impulsivity, attention, intelligence, short term memory, long term memory, and cognitive flexibility, with the largest effect size being related to cognitive impulsivity (SDM = 0.881, p <0.005), and the smallest effect size being related to intelligence (SDM = 0.164, p < 0.05) according to Cohen's benchmark criteria. No association was found between chronic smoking and motor impulsivity (SDM = 0.105, p = 0.248). Future research is needed to investigate further this association by focusing on better methodologies and alternative methods for nicotine administration.

Accuracy of point-of-care ultrasound by pediatric emergency physicians for testicular torsion.

INTRODUCTION: Acute scrotum is a common presentation to the pediatric emergency department, and ultrasound is frequently used to narrow the differential diagnosis. Point-of-care ultrasound (POCUS) is increasingly used by urologists and emergency physicians and could potentially be used to detect pediatric testicular torsion. OBJECTIVES: This study aimed to determine the accuracy of POCUS by pediatric emergency physicians in diagnosing testicular torsion and the agreement between point-of-care ultrasound and final diagnosis for other causes of acute scrotum. STUDY DESIGN: A chart review of patients presenting to the study emergency department who received POCUS by a pediatric emergency physician, as well as radiology department ultrasound and/or surgery, was performed. Charts were reviewed for POCUS diagnoses, final diagnoses, and imaging time metrics. RESULTS: A total of 120 patients met study criteria, with 12 cases of testicular torsion. The diagnostic accuracy of POCUS for testicular torsion is described in the summary table. For all causes of acute scrotum, point-of-care ultrasound agreed with final diagnosis in 70% (95% confidence interval [CI] 62-78%) of cases, and more experienced point-of-care ultrasound users displayed higher agreement with final diagnosis. Point-of-care ultrasound results were generated a median of 73 min (Q1 = 51, Q3 = 112) before radiology department ultrasound results. DISCUSSION: Scrotal POCUS performed by pediatric emergency physicians appears to be an accurate tool to detect testicular torsion in children with acute scrotum and saves time compared with radiology ultrasound. The study results may not be generalizable to hospitals without a multidisciplinary POCUS system for quality assurance and image sharing. Future work on POCUS for acute scrotum should investigate its impact on patient outcomes, cost-effectiveness, and family satisfaction. CONCLUSION: Point-of-care ultrasound by pediatric emergency physicians is accurate for detecting testicular torsion in children with acute scrotum and could expedite diagnosis of this time-sensitive condition.

Evidence for an influence of chemokine ligand 3-like 1 (CCL3L1) gene copy number on susceptibility to rheumatoid arthritis.

OBJECTIVE: There is increasing evidence that gene copy-number variation influences phenotypic variation. Chemokine ligand 3-like 1 (CCL3L1) is encoded by a variable copy-number gene, and binds to several pro-inflammatory cytokine receptors, including chemokine receptor 5 (CCR5). Considering lymphocyte recruitment by beta-chemokines is a feature of autoimmunity, and that the CCR5Delta32 variant is associated with protection to rheumatoid arthritis (RA), we hypothesised that CCL3L1 copy-number influences susceptibility to RA and type 1 diabetes (T1D). METHODS: We measured CCL3L1 copy-number in 1136 RA cases from New Zealand (NZ) and the UK, 252 NZ T1D cases and a total of 1470 controls. All subjects were ancestrally Caucasian. RESULTS: A copy-number higher than 2 (the most common copy number) was a risk factor for RA in the NZ cohort (odds ratio (OR) 1.34, 95% CI 1.08-1.66, p = 0.009) but not the smaller UK RA cohort (OR 1.09, 95% CI 0.75-1.60, p = 0.643). There was evidence for association in the T1D cohort (OR 1.46, 95% CI 0.98-2.20, p = 0.064) and in the combined RA/T1D cohort (OR 1.30, 95% CI 1.00-1.54, p = 0.003). Genetic interaction between CCL3L1 dosage and CCR5 genotype was found; the increased genetic risk conferred by higher CCL3L1 copy-number was ablated by a dysfunctional CCR5 (CCR5Delta32). CONCLUSIONS: These data suggest that increased CCL3L1 expression may enhance inflammatory responses and increase the chance of autoimmune disease. Genetic interaction data were consistent with a biologically plausible model; CCR5Delta32 protects against RA and T1D by blocking signalling through the CCR5 pathway, mitigating the pro-inflammatory effects of excess CCL3L1.

Avian proteomics: advances, challenges and new technologies.

Proteomics is defined as an analysis of the full complement of proteins of a cell or tissue under given conditions. Avian proteomics, or more specifically chicken proteomics, has focussed on the study of individual tissues and organs of interest to specific researchers. Researchers have looked at skeletal muscle and growth, and embryonic development and have performed initial studies in avian disease. Traditional proteomics involves identifying and cataloguing proteins in a cell and identifying relative changes in populations between two or more states, be that physiological or disease-induced states. Recent advances in proteomic technologies have included absolute quantification, proteome simplification and the ability to determine the turnover of individual proteins in a global context. This review discusses the current developments in this relatively new field, new technologies and how they may be applied to biological questions, and the challenges faced by researchers in this ever-expanding and exciting field.

Geographic isolation facilitates the evolution of reproductive isolation and morphological divergence.

Geographic isolation is known to contribute to divergent evolution, resulting in unique phenotypes. Oftentimes morphologically distinct populations are found to be interfertile while reproductive isolation is found to exist within nominal morphological species revealing the existence of cryptic species. These disparities can be difficult to predict or explain especially when they do not reflect an inferred history of common ancestry which suggests that environmental factors affect the nature of ecological divergence. A series of laboratory experiments and observational studies were used to address what role biogeographic factors may play in the ecological divergence of Hyalella amphipods. It was found that geographic isolation plays a key role in the evolution of reproductive isolation and divergent morphology and that divergence cannot be explained by molecular genetic variation.

The aquatic annelid fauna of the San Marcos River headsprings, Hays County, Texas.

The San Marcos River in Central Texas has been well studied and has been demonstrated to be remarkably specious. Prior to the present study, research on free-living invertebrates in the San Marcos River only dealt with hard bodied taxa with the exception of the report of one gastrotrich, and one subterranean platyhelminth that only incidentally occurs in the head spring outflows. The remainder of the soft-bodied metazoan fauna that inhabit the San Marcos River had never been studied. Our study surveyed the annelid fauna and some other soft-bodied invertebrates of the San Marcos River headsprings. At least four species of Hirudinida, two species of Aphanoneura, one species of Branchiobdellida, and 11 (possibly 13) species of oligochaetous clitellates were collected. Other vermiform taxa collected included at least three species of Turbellaria and one species of Nemertea. We provide the results of the first survey of the aquatic annelid fauna of the San Marcos Springs, along with a dichotomous key to these annelids that includes photos of some representative specimens, and line drawings to elucidate potentially confusing diagnostic structures.

Probucol reduces the rate of association of apolipoprotein C-III with dimyristoylphosphatidylcholine.

The effect of low concentrations of probucol and cholesterol on the association of dimyristoylphosphatidylcholine with human plasma apolipoprotein C-III was studied. Liposomes of dimyristoylphosphatidylcholine with or without probucol or cholesterol were prepared by swelling the lipids in buffer at 37 degrees C. The association of apolipoprotein C-III with the liposomes was determined at 24 degrees C by measuring the rate of clearing of turbidity at 400 nm following addition of protein. At a weight ratio of probucol/dimyristoylphosphatidylcholine of 1:25 (5 mol% probucol), the rate of clearing of liposomes was decreased by 60%; 5 mol% cholesterol had no effect on the clearing rate. Liposomes were then added to the preformed apolipoprotein C-III/lipid micelles. In the absence of probucol, the added liposomes cleared rapidly regardless of the presence or absence of cholesterol. With 5 mol% probucol, almost no decrease in absorbance was noted on addition of liposomes to the micelles. These data show that probucol reduces the rate of association of an apolipoprotein with lipid and suggests that the interaction of probucol with lipid may modify the assembly and/or metabolism of lipoproteins.

Promotion of beta-structure by interaction of diabetes associated polypeptide (amylin) with phosphatidylcholine.

The interaction of the diabetes associated polypeptide (amylin) with dimyristoylphosphatidylcholine (DMPC) was assessed by measurements of turbidity (absorbance at 400 nm) and secondary structure by CD spectroscopy. In trifluoroethanol, human amylin adopts a highly alpha-helical conformation while the rat peptide is less structured. In water, the rat peptide is largely disordered and the human peptide exhibits a combination of alpha- and beta-structures. Mixtures of DMPC and the rat peptide have no effect on either the turbidity of the DMPC or the CD spectrum of the peptide. By contrast, mixtures of the human peptide with DMPC form relatively clear mixtures similar to those observed with amphipathic alpha-helical peptides, but the structure adopted, based on the CD spectrum, is largely beta. These data demonstrate that fundamental differences in the structures adopted by amylins from human and rat species exist in mixtures with DMPC and suggest that these differences may be related to the formation of amyloid fibrils in the human amylin peptide which are not observed in the rat peptide.

Kinetics of the interaction of amphipathic alpha-helical peptides with phosphatidylcholines.

The rate of association of three amphipathic alpha-helical peptides with phosphatidylcholine liposomes was examined to provide more detailed information on the relationship between peptide length and the kinetics of lipid interactions. When added to dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) liposomes from a guanidine-HCl solution, a ten residue peptide rapidly decreased the turbidity of the liposomes. However, a related 17-residue peptide had only a minimal effect on liposome turbidity. A 14-residue peptide was intermediate in effectiveness. Similarly, when liposomes were added to peptides dissolved in an aqueous buffer, the ten residue peptide but not the 17-residue peptide cleared the turbid liposomes and the 14-residue peptide was intermediate in efficacy. The rate of binding to the liposomes was compared with the three peptides by measurements of the kinetics of energy transfer from the single tryptophan residue of the peptides to a fluorescent probe in the bilayer interior. The tryptophan residue of the ten residue peptide effectively transferred energy to the probe, while that of the 14-residue peptide was less effective. Little or no energy transfer was observed with the 17-residue peptide. The binding of the 10 residue peptide was rapid and complete within < 100 ms. The 14-residue peptide bound more slowly, but still within seconds. The time frames for binding are an order of magnitude shorter than those observed for lipid clearing. The relationship between peptide length, liposome clearing and lipid binding kinetics is discussed in terms of a possible competing peptide-peptide interaction in the aqueous phase and a slow rearrangement of the lipid bilayer.

Cholesterol transfer from small and large unilamellar vesicles.

The rates of transfer of [14C]cholesterol from small and large unilamellar cholesterol/egg yolk phosphatidylcholine vesicles to a common vesicle acceptor were compared at 37 degrees C. The rate of exchange of cholesterol between vesicles of identical cholesterol concentrations (20 mol%) did not differ from the rate of transfer from donor vesicles containing 20 mol% cholesterol to egg yolk PC vesicles. Further, the rate of transfer of [14C]cholesterol from vesicles containing 15 mol% dicetyl phosphate (to confer a negative charge) was not different from the rate of transfer from neutral vesicles. However, the half-time for transfer of [14C]cholesterol from large unilamellar donor vesicles was about 5-times greater (10.2 h, 80 nm diameter) than from small unilamellar vesicles (2.3 h, 23 nm diameter). These data suggest that increased curvature in small unilamellar vesicles reduces cholesterol-nearest neighbor interactions to allow a more rapid transfer of cholesterol into the aqueous phase.

Antioxidant activity of probucol and its effects on phase transitions in phosphatidylcholine liposomes.

The effect of probucol on the phase behavior of dimyristoylphosphatidylcholine (DMPC) was examined by fluorescence polarization and differential scanning calorimetry (DSC). Probucol broadens and shifts the temperature of the main phase transition of DMPC liposomes as measured by fluorescence polarization with diphenylhexatriene and trimethyl-ammonium-diphenylhexatrine at concentrations as low as 5 mole%. As measured by DSC, probucol reduces the transition temperature of the gel----liquid-crystalline phase transition of DMPC by approx. 2 C degrees at all concentrations above about 5 mole% probucol and eliminates the pretransition at less than 1 mole%. In addition, the phase transition of DMPC is broadened and the enthalpy of the transition reduced by approx. 50%. Even at high concentrations of probucol, the gel----liquid-crystalline phase transition of DMPC is not eliminated. Similar effects are observed with dipalmitoylphosphatidylcholine liposomes. Based on these DSC measurements, measurements of the melting of probucol in dry mixtures with DMPC and observations of probucol mixtures with DMPC under polarizing optics, the maximum solubility of probucol in DMPC is approx. 10 mole%. This concentration exceeds that required (approx. 0.5 mole%) to prevent peroxidation of 10 mole% arachidonic acid in DMPC liposomes for 30 min in the presence of 0.05 mM Fe(NH4)(SO4)2 at 4 degrees C. Thus, probucol has a limited solubility in saturated phosphatidylcholine bilayers, but is an effective antioxidant at concentrations lower than its maximum solubility.

Fatty acyl chain specificity of phosphatidylcholine hydrolysis catalyzed by lipoprotein lipase. Effect of apolipoprotein C-II and its (56-79) synthetic fragment.

Mixed acyl chain phosphatidylcholine molecules in Triton N-101 micelles were employed as substrates for lipoprotein lipase to test which substrate acyl chain has the greatest effect on activation of the enzyme by apolipoprotein C-II. The phospholipase A1 activity of lipoprotein lipase was measured by pH-stat. The activation factor (lipoprotein lipase activity plus apolipoprotein C-II/activity minus apolipoprotein C-II) increased monotonically with apolipoprotein C-II concentration up to 1 microM apolipoprotein C-II at an enzyme concentration of 0.01 microM. The maximal activation factor for phosphatidylcholine substrate molecules with sn-2 acyl chain lengths of 14 averages 14.8. By contrast, for sn-2 acyl chain lengths of 16 the activation factor was 29.2. Varying the sn-1 acyl chain length had no significant effect on the activation factor. The chain-length dependence of the activation factor is similar with the apolipoprotein C-II peptide fragment comprising residues 56-79, which does not include the lipid-binding region of apolipoprotein C-II. These data are consistent with a model for activation of lipoprotein lipase in which residues 56-79 bind to lipoprotein lipase and alter the interaction of the sn-2 acyl chain of the phosphatidylcholine (PC) substrate or the lysoPC product within the activated state complex.

Lipid and membrane interactions of neuropeptide Y.

The interactions of neuropeptide Y with dimyristoylphosphatidylcholine and cell membranes were examined by several physical techniques to probe the potential role of its putative C-terminal amphipathic alpha-helix. Neuropeptide Y binding was demonstrated by a rapid release of entrapped 6-carboxyfluorescein and a rapid decrease in the turbidity of dimyristoylphosphatidylcholine liposomes. In addition, an increase in tyrosine fluorescence intensity and an increase in the anisotropy of diphenylhexatriene in dimyristoylphosphatidylcholine liposomes was observed. In isolated, aortic smooth muscle cell membranes, the anisotropy of diphenylhexatriene increased as a function of added neuropeptide Y. The concentration range (low microM) over which neuropeptide Y increases the polarization of diphenylhexatriene in cell membranes is similar to the range in which it inhibits isoproterenol-stimulated cAMP accumulation. This inhibition is not affected by pertussis toxin, nor does neuropeptide Y cause the release of preloaded [3H]adenine from cells into the medium. These data suggest that neuropeptide Y contains an amphipathic alpha-helical region which interacts with lipids in much the same way as the amphipathic alpha-helical regions of the plasma apolipoproteins and that the inhibition of isoproterenol-stimulated cAMP accumulation at low microM concentrations of peptide may be the result of an alteration in the cell membrane bilayer structure.