Gastric blood flow

Summary In summary, the vascular bed of the stomach is an area of great potential importance to both gastric and vascular physiologists. There are available many technics for its investigation. Simultaneous study of both hemodynamic and secretory phenomena can be conducted on the stomach. In the next few years information concerning the circulation of the stomach may help elucidate problems in the physiology and pathology of gastric secretion. Hightower observed recently: The topic of visceral circulation, particularly as it pertains to the digestive tract, has not been commented upon in recent...Reviews of Physiology. This subject has become increasingly important in the past few years and is an area with which physiologists interested in the digestive system will become more and more concerned.³³     

Transient right bundle branch block following blunt chest trauma

A 38 year old man with previously normal electrocardiograms suffered a direct blow to the chest which resulted in electrocardiographic changes consistent with transient right bundle branch block. Serial enzyme determinations documented a rise in fraction 5 of serum lactic dehydrogenase. Evaluation subsequent to the injury were all within normal limits. An unexplained finding of paradoxical splitting of the pulmonic component of the second heart sound is noted.     

Mechanism of interferon action: Phosphorylation of protein synthesis initiation factor eIF-2 in interferon-treated human cells by a ribosome-associated kinase processing site specificity similar to hemin-regulated rabbit reticulocyte kinase

The phosphorylation of purified protein synthesis factors catalyzed by protein kinase preparations isolated from interferon-treated human amnion cells was examined. Ribosomal salt-wash fractions prepared from interferon-treated human cells contained a protein kinase that catalyzed the [gamma-(32)P]ATP-mediated phosphorylation of the 38,000-dalton subunit of eukaryotic initiation factor 2 (eIF-2alpha); this kinase activity was significantly enhanced in interferon-treated as compared to untreated cells. The tryptic [(32)P]phosphopeptide pattern obtained for eIF-2alpha phosphorylated by the interferon-mediated human kinase was indistinguishable from the pattern obtained for eIF-2alpha phosphorylated by the hemin-regulated rabbit reticulocyte kinase when analyzed by thin-layer chromatography with three different solvent systems and by high-voltage electrophoresis. O-[(32)P]Phosphoserine was liberated by partial acid hydrolysis from eIF-2alpha phosphorylated by either the human or the rabbit kinase. In addition to the phosphorylation of eIF-2alpha, interferon treatment of human cells enhanced the phosphorylation of two additional ribosome-associated proteins designated P(1) and P(f). The major phosphoester linkage observed for the human, as well as murine, phosphoprotein P(1) was O-phosphoserine. The interferon-mediated phosphorylation of both eIF-2alpha and protein P(1) was dependent upon the presence of RNA with double-stranded character; P(f) phosphorylation was not affected by double-stranded RNA. These results suggest that the interferon-mediated ribosome-associated human protein kinase catalyzes the phosphorylation of eIF-2alpha in a site-specific manner that is apparently identical with the reaction catalyzed by the hemin-regulated rabbit reticulocyte kinase; hence, the phosphorylation of eIF-2 may play a role in regulating the initiation of translation in interferon-treated cells.     

Ethanol increases GABAergic transmission at both pre- and postsynaptic sites in rat central amygdala neurons

We examined the interaction of ethanol with the gamma-aminobutyric acid (GABA)ergic system in neurons of slices of the rat central amygdala nucleus (CeA), a brain region thought to be critical for the reinforcing effects of ethanol. Brief superfusion of 11-66 mM ethanol significantly increased GABA type A (GABA(A)) receptor-mediated inhibitory postsynaptic potentials (IPSPs) and currents (IPSCs) in most CeA neurons, with a low apparent EC(50) of 20 mM. Acute superfusion of 44 mM ethanol increased the amplitude of evoked GABA(A) IPSPs and IPSCs in 70% of CeA neurons. The ethanol enhancement of IPSPs and IPSCs occurred to a similar extent in the presence of the GABA type B (GABA(B)) receptor antagonist CGP 55845A, suggesting that this receptor is not involved in the ethanol effect on CeA neurons. Ethanol superfusion also decreased paired-pulse facilitation of evoked GABA(A) IPSPs and IPSCs and always increased the frequency and sometimes the amplitude of spontaneous miniature GABA(A) IPSCs as well as responses to local GABA application, indicating both presynaptic and postsynaptic sites of action for ethanol. Thus, the CeA is the first brain region to reveal, without conditional treatments such as GABA(B) antagonists, consistent, low-dose ethanol enhancement of GABAergic transmission at both pre- and postsynaptic sites. These findings add further support to the contention that the ethanol-GABA interaction in CeA plays an important role in the reinforcing effects of ethanol.     

The Evolutionary Development of Modifier Genes

The main findings of a study of the evolution of modifier gene frequencies in models of deterministic population genetics are presented. A wide variety of random mating systems are subject to selection with modifiers operating, in different cases, on mutation rates, dominance, migration between subpopulations, and linkage between other loci. In all these instances the modifier frequencies evolve in such a way as to maximize the mean fitness of the population at equilibrium. This is remarkable since, except for the dominance modifier, the modifier genes are selectively neutral in the sense that they do not affect the fitness of their individual carriers. In nonrandom mating systems the mean fitness concept is not well defined, and there does not appear to be such a simple principle governing the evolution of modifier frequencies. In assortative mating systems modifiers favoring reduced assortment propensities tend to increase. In contrast, for selfing-outcrossing systems modifiers favoring increased selfing tend to increase.     

Administration of pegylated recombinant human megakaryocyte growth and development factor to humans stimulates the production of functional platelets that show no evidence of in vivo activation

This report describes the effect of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on platelet production and platelet function in humans. Subjects with advanced solid tumors received PEG-rHuMGDF daily for up to 10 days. There was no increase in circulating platelet count at doses of 0.03 or 0.1 microgram/kg/d by day 12 of study. At doses of 0.3 and 1.0 microgram/kg/d there was a threefold median increase (maximum 10-fold) in platelet count by day 16. The platelets produced in vivo in response to PEG-rHuMGDF showed unchanged aggregation and adenosine triphosphate (ATP)-release responses in in vitro assays. Tests included aggregation and release of ATP in response to adenosine diphosphate (ADP) (10, 5, 2.5, and 1.25 mumol/L), collagen (2 micrograms/mL), thrombin-receptor agonist peptide (TRAP, 10 mumol/L) and ristocetin (1.5 mg/mL). Administration of aspirin to an individual with platelet count of 1,771 x 10(3)/L resulted in the typical aspirin-induced ablation of the normal aggregation and ATP-release response to stimulation with arachidonic acid (0.5 mg/mL), collagen, and ADP (2.5 and 1.25 mumol/L). There was no change in the expression of the platelet-surface activation marker CD62P (P-selectin) nor induction of the fibrinogen binding site on glycoprotein IIb/IIIa as reported by the monoclonal antibody, D3GP3. An elevation of reticulated platelets was evident after 3 days of treatment with PEG-rHuMGDF and preceded the increase in circulating platelet count by 5 to 8 days; this reflected the production of new platelets in response to PEG-rHuMGDF. At later time points, the mean platelet volume (MPV) decreased in a manner inversely proportional to the platelet count. Levels of plasma glycocalicin, a measure of platelet turnover, rose 3 days after the initial increase in the peripheral platelet count. The level of plasma glycocalicin was proportional to the total platelet mass, suggesting that platelets generated in response to PEG-rHuMGDF were not more actively destroyed. Thus, the administration of PEG-rHuMGDF, to humans, increased the circulating platelet count and resulted in fully functional platelets, which showed no detectable increase in reactivity nor alteration in activation status.     

The use of transesophageal echocardiography to avoid left atrial thrombus during percutaneous mitral valvuloplasty

During mitral balloon valvuloplasty, transesophageal echocardiography (TEE) has been employed for the accurate placement of the transseptal needle, guide wires, and balloon catheters and to provide an immediate evaluation of the results of the procedure. We describe a case demonstrating that TEE can be used to avoid a left atrial appendage thrombus during the placement of wires and catheters. With TEE guidance, we feel left atrial appendage thrombi are no longer an absolute contraindication to percutaneous mitral valvuloplasty. © 1993 Wiley-Liss, Inc.