Area postrema-lesions increase operant responding to sucrose in rats

Rats with lesions of the area postrema (APX) are known to exhibit an enhanced intake of highly palatable foods such as sweetened condensed milk and cookies. These observations suggest the possibility that APX rats find these foods more rewarding and will work harder to obtain these foods. Sham and APX rats were tested on fixed ratio (FR) and progressive ratio (PR) schedules. APX rats consistently pressed more times to receive sucrose solution and attained both FR 3 and FR 5 criteria significantly faster than sham-lesioned control rats. Furthermore, rats with APX had significantly higher break points than sham-lesioned control rats on a progressive ratio schedule. These results support the hypothesis that rats with lesions of the area postrema will consistently work harder to obtain a highly palatable food reward.     

Reevaluation of bacteriocinogeny in Neisseria gonorrhoeae.

Bacteriocin typing has been described previously and proposed for typing gonococci. A survey has been made of 150 strains of N. gonorrhoeae from various places to determine the feasibility of a gonocin typing system. All strains were found to produce an inhibitory substance which inhibited all strains of gonococci tested, one strain of Neisseria flavescens, two strains of Neisseria meningitidis, as well as the producing strain itself. The inhibitory activity was enhanced by supplementary glucose, reduced by supplementary serum, and unaffected by the addition of HEPES buffer, by the temperature of incubation, or by the exposure of potential producer strains to sublethal concentrations of mitomycin C. This nonspecific inhibitory activity differed from that of a putative bacteriocin produced by a strain of N. meningitidis, in that the latter inhibited most other meningococci but not the producer strain itself. Bacteriocinogeny has not yet been convincingly demonstrated in N. gonorrhoeae, and gonocin typing has not yet been shown to be feasible. Production of the nonspecific inhibitor may have obscured past attempts to demonstrate type-specific gonococcal bacteriocin.     

Expression of opioid peptides in tumors

We looked for opioid peptides and their precursors in 108 tumors of both neuroendocrine and nonneuroendocrine origin, using a monoclonal "pan-opioid" antibody, 3-E7, which recognizes the tetrapeptide Tyr-Gly-Gly-Phe (the sequence responsible for pharmacologic activity in all known opioid peptides), in conjunction with polyclonal antibodies directed against representative peptides of each of the three precursors (alpha-endorphin, [met]enkephalin-Arg-Gly-Leu, and dynorphin B). Using the avidin-biotin immunoperoxidase technique, we observed consistent cytoplasmic immunoreactivity (at least focally) in all of 15 adrenal pheochromocytomas, all of 6 thyroid medullary carcinomas, and all of 5 pituitary adenomas. Opioid staining was also observed in parathyroid adenomas (8 of 9), pancreatic islet-cell tumors (7 of 10), carcinoid tumors from various sites (18 of 26), and paragangliomas (1 of 2). There was no immunoreactivity in pulmonary small-cell carcinomas, Merkel-cell tumors of skin, neuroblastomas, or any of the non-neuroendocrine tumors examined. The expression of alpha-endorphin, [met]enkephalin-Arg-Gly-Leu, and dynorphin B varied from tumor to tumor; however, positive staining with the "pan-opioid" antibody was found in each tumor containing at least one of the three precursors. Opioid peptide immunoreactivity was also detected in non-neoplastic cells of the adrenal medulla, pancreatic islets, pituitary, intestinal and bronchial mucosa, and intestinal myenteric plexuses. We conclude that opioid expression within tumors is most likely due to enhanced expression of a normal cell product and that opioid peptides are useful markers of neuroendocrine differentiation in many tumors.     

Ultrastructure of the early human implantation in vitro

Four hatched human blastocysts obtained after in-vitro fertilizationand development were placed on monolayer cell cultures of humanendometrial epithelium, and subsequently examined by transmissionelectron microscopy. All four blastocysts became adherent tothe monolayer and three implanted and exhibited outgrowth oftheir trophoblastic cells. During implantation the blastocystsdifferentiated into mural and polar trophoblastic cells, andembryonic cells including endodermal cells. The endometrialcells were displaced and stacked into a multilayer at the peripheryof the implantation sites, allowing the trophoblastic cellsto come in contact with the culture dish. The endometrial cellsdisplayed local exo- or endo-cytosis where they contacted thetrophoblastic cells. The trophoblastic cells were not observedto be phagocytosing endometrial cells. These observations suggestthat human blastocysts portray an intrusive type of implantationduring the initial stages.     

Proposed methods for the measurement of regional renal blood flow using heat transfer analysis

The kidney, with its heterogeneous regional perfusion in the two anatomically and functionally distinct vascular beds of the renal cortex and medulla, and with its nonuniform blood vessel geometries, presents a unique challenge for measuring intrarenal blood flow distribution. Determining whole organ perfusion, on the other hand, is comparatively simple for the kidney, but it provides relatively little information about the suspected dependency of renal excretory function on local perfusion rate. Among the variety of methods proposed for gauging regional renal blood flow, some depend on measuring one or more of the tissue's thermal properties. The most straightforward, but least reliable, involve measurements either of focal tissue temperature alone, or of regional tissue thermal gradients. Simply using heat as a diffusible indicator, however, is unreliable as a measure of blood flow, for many of the same reasons that using an inert gas in a dilution technique is unreliable. Recently developed thermal analytical methods, though, hold promise for measuring local tissue blood flow with accuracy and precision. Two of them are reviewed here. One depends on measurement of the effective thermal conductivity of a small mass of tissue by evaluating the steady state ratio between regional unidirectional heat flux across it and the associated temperature gradient in one vector along a segment of it through an imposed spheroidal heat field. The other depends on analyses of tissue temperature decay subsequent to a controlled pulse of heat delivered through a small inserted thermistor bead. Both techniques use bioheat transfer equations to deduce regional blood flow Research by K.R. Holmes and M.M. Chen was supproted by NIH-NHLBI Grant HL27011, that by T. Adams and S.R. Heisey through the Michigan Heart Association, and that by W.S. Spielman through a grant from the NSF (PCM 8110588) who is a recipient of NIH Research Career Development Award HL01010.     

Clinical use of the abiomed BVS 5000 as a pulsatile extracorporeal membrane oxygenation unit

The traditional extracorporeal membrane oxygenation circuit uses a centrifugal pump. These pumps require close monitoring and are subject to complications. In addition, they do not take advantage of the potential benefits of pulsatile flow. These extracorporeal membrane oxygenation circuits use a single pump with an inline oxygenator. If cardiac failure persists after respiratory recovery has occurred, removal of the oxygenator requires an additional procedure to convert the patient to biventricular support. This report describes a circuit in which an oxygenator is connected to a pulsatile ventricular assist device. Single and dual circuit configurations are illustrated. Recommendations for pulmonary care during support are also described.     

No association between CHRNA7 microsatellite markers and attention-deficit hyperactivity disorder.

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable, common psychiatric disorder of childhood that probably involves several genes. There are several lines of evidence suggesting that the nicotinic system may be functionally significant in ADHD. First, nicotine promotes the release of dopamine and has been shown to improve attention in adults with ADHD, smokers, and nonsmokers. Second, ADHD is a significant risk factor for early initiation of cigarette smoking in children and maternal cigarette smoking appears to be a risk factor for ADHD. Finally, animal studies in rats and monkeys also suggest that nicotine may be involved in attentional systems and locomotor activity. The nicotinic system has previously been studied in schizophrenia where the neuronal nicotinic acetylcholine receptor alpha 7 subunit gene (CHRNA7) has been implicated in decreased P50 inhibition and attentional disturbances in patients with schizophrenia and in many of their nonschizophrenic relatives. Three known microsatellite markers (D15S165, D15S1043, and D15S1360) near the nicotinic acetylcholine alpha 7 receptor gene, CHRNA7, were studied in 206 ADHD parent-proband trios of children aged 5-16 with ADHD according to DSM-IV criteria. Children with known major medical or psychiatric conditions or mental retardation (IQ < 70) were excluded from the study. Markers D15S165 and D15S1360 were in linkage disequilibrium. The extended Transmission Disequilibrium Test analyses demonstrated no evidence that variation at the microsatellite markers D15S1360, D15S1043, and D15S165 influences susceptibility to ADHD. However, it remains possible that the CHRNA7 gene and other nicotinic system genes may be involved in conferring susceptibility to ADHD.