Kit-like immunoreactivity in the zebrafish gastrointestinal tract reveals putative ICC.

Gastrointestinal (GI) motility results from the coordinated actions of enteric neurons, interstitial cells of Cajal (ICC), and smooth muscle cells. The GI tract of the zebrafish has a cellular anatomy that is essentially similar to humans. Although enteric nerves and smooth muscle cells have been described, it is unknown if ICC are present in the zebrafish. Immunohistochemistry and PCR were used determine expression for the zebrafish Kit orthologue in the zebrafish gastrointestinal tract. Cells displaying Kit-like immunoreactivity were identified in the muscular layers of the adult zebrafish gastrointestinal tract. Two layers of Kit-positive cells were identified, one with multipolar cells located between the longitudinal and circular smooth muscle layers and one with simple bipolar cells located deep in the circular muscle layer. Primers specifically designed to amplify mRNA coding for two zebrafish kit genes, kita and kitb, and two kit ligands, kitla and kitlb, amplified the expected transcript from total RNA isolated from zebrafish GI tissues. The Sparse mutant, a kita null mutant, showed reduced contraction frequency and increased size of the GI tract indicating a functional role for kita. These data establish the presence of a cellular network with Kit-like immunoreactivity in the myenteric plexus region of the zebrafish GI tract, adjacent to enteric neurons. Expression of kita and kitb, and the ligands kitla and kitlb, were verified in the adult GI tract. The anatomical arrangement of the Kit-positive cells strongly suggests that they are ICC.

High-spatial-resolution multistation MR imaging of lower-extremity peripheral vasculature with segmented volume acquisition: feasibility study.

A method of three-station three-dimensional magnetic resonance (MR) angiography of the lower extremities with segmented volume acquisition is presented. Three-dimensional MR angiographic data were acquired in two passes, with the central k-space views acquired during the arterial phase for the more proximal stations. This allowed a faster bolus injection rate and potentially improved visualization of the tibioperoneal arteries.

Preferential arterial imaging using gated thick-slice gadolinium-enhanced phase-contrast acquisition in peripheral MRA.

PURPOSE: To investigate the feasibility of preferential arterial imaging using gadolinium-enhanced thick-slice phase-contrast imaging. METHODS: Six healthy volunteers were studied using a peripheral-gated segmented k-space CINE phase-contrast pulse sequence using four views per RR interval with flow encoding in the superior-inferior direction. Images at the level of the popiteal trifurcation were acquired postcontrast with different section thicknesses (4-8 cm) and VENC values (20-150 cm/sec), and phase-difference processing. RESULTS: The post-gadolinium contrast-enhanced thick-slice phase-contrast acquisitions demonstrated the ability to visualize the tibio-peroneal (trifurcation) arteries, especially in systole. With MR contrast agents, the signal from blood is raised significantly above that of stationary tissue from T(1) shortening such that the partial volume artifact is reduced in thick-slice acquisitions. Furthermore, by selecting the VENC value as a function of the cardiac cycle, the noise floor can be raised to selectively suppress flow values less than that of the noise threshold, allowing better accentuation of arterial structures at systole. CONCLUSIONS: Thick-slice phase-contrast acquisition with phase-difference processing has been observed to reduce partial volume artifacts when an MR contrast agent substantially increases signal in the vasculature over that of normal background tissue. Preferential arterial images can be obtained by either increasing the VENC value to selectively suppress signal from slow flow in the veins or by subtracting the diastolic phase image from the peak systolic phase image. J. Magn. Reson. Imaging 2001;13:714-721.

Monophosphoryl lipid A protects adult rat cardiac myocytes with induction of the 72-kD heat shock protein: a cellular model of pharmacologic preconditioning.

We examined the in vitro preconditioning effect of non-toxic derivative of endotoxin, monophosphoryl lipid A (MLA) in adult rat cardiac myocytes. Cultured 5-7-day-old myocytes were preconditioned for 4 h by treatment with 200 ng/ml MLA. Twenty h later, cells were subjected to simulated ischemia by incubation in 0.75 mm sodium hydrosulfite, 12 mM KCl, 20 mM dl-lactic acid and 10 mM 2-deoxy-D-glucose (pH 6.5) for 2 h. MLA caused a significant reduction in the levels of LDH from 286+/-8 units/l in controls to 165+/-5 units/l (mean+/-s.e.m.; P<0.0001). Similarly, CK significantly decreased from 104+/-3.1 in controls to 85+/-1.4 U/l (P<0.001). Western blot analysis indicated a significant accumulation of 72 kD heat shock protein in MLA treated as compared to control cells. No changes in 27, 32, and 90 kD heat shock proteins were discernible in the MLA treated group. These data suggest a significant "anti-ischemic" effect of MLA in myocytes that is accompanied by induction of 72 kD heat shock protein.

Pulmonary artery banding and subaortic stenosis in patients with single ventricle: surgical alternatives and clinical outcome.

Subaortic obstruction is a potential problem in patients with single ventricle and a subaortic outflow chamber. Previous reports have indicated an association between pulmonary artery banding and the development of subaortic obstruction. The purpose of this study was to determine the incidence of subaortic obstruction in our patients with this cardiac anomaly who have undergone pulmonary artery banding, and to determine the eventual outcome in those who did develop obstruction. By reviewing cardiac catheterizations performed between 1977 and 1985, we found 36 patients with single ventricle and a subaortic outflow chamber. Ten patients had been lost to follow-up or had died within 3 months of banding. Twelve of the remaining 26 patients developed a pressure gradient between the left ventricle and ascending aorta, although 7 of these 12 had minimal gradients. Eight of the 12 have undergone further surgery, with the best results in patients who underwent a combined modified Fontan and Damus-Kaye-Stansel procedure. We believe that although subaortic obstruction may develop in patients with single ventricle after pulmonary artery banding, the degree of obstruction is often minimal, and in more severe cases the obstruction can be alleviated with a Damus-Kaye-Stansel procedure. (Texas Heart Institute Journal 1992; 19:15-20)

The specific protein phosphatase inhibitor okadaic acid differentially modulates insulin action.

The pleiotropic nature of insulin action suggests diverse mechanisms of signal transduction for the hormone. The specific protein phosphatase inhibitor, okadaic acid, is utilized to differentiate metabolic pathways that may be regulated by phosphorylation or dephosphorylation of key enzymes. In H-35 hepatoma cells, okadaic acid inhibits insulin-stimulated glycogen synthesis with an IC50 of 400 nM. In contrast, activation of lipogenesis by insulin is inhibited with an IC50 of 50 nM okadaic acid. The toxin also inhibits stimulation of lipogenesis in these cells by the insulin-sensitive inositol glycan enzyme modulator. In isolated rat adipocytes, insulin-stimulated lipogenesis is also inhibited by okadaic acid with an IC50 of approximately 1,700 nM. The antilipolytic effect of insulin in these cells is more sensitive to okadaic acid, exhibiting an IC50 of 150 nM. Maximal activation of lipogenesis by insulin is dramatically reduced by okadaic acid with no effect on the concentration required for half-maximal activation, whereas the sensitivity of insulin-induced antilipolysis is attenuated by okadaic acid, with no apparent reduction in the maximal effect of the hormone. Taken together, these data suggest that specific phosphatases may be differentially involved in some of the metabolic pathways regulated by insulin.

Enzymatic assay procedures that employ high-performance liquid chromatography: competition between phosphoribosyltransferases for a common substrate.

A survey of the phosphoribosyltransferase (PRTase) activities in yeast has been accomplished using reversed-phase high-performance liquid chromatographic assay procedures. The following bases were observed to be utilized during phosphoribosyl pyrophosphate (PRibPP)-dependent nucleotide syntheses: adenine, xanthine, hypoxanthine, guanine, uracil, orotate, nicotinamide, nicotinate and quinolinate. Gradient elution procedures have also been perfected that allow the separation of the two following sets of PRTase assay components: (1) adenosine monophosphate, nicotinate mononucleotide, orotate, adenosine triphosphate, nicotinate, adenosine diphosphate, inosine monophosphate and hypoxanthine, and (2) nicotinate mononucleotide, nicotinamide mononucleotide, adenosine triphosphate, nicotinate, adenosine diphosphate and nicotinamide. Separation 1 has been employed to examine the PRibPP allocation among the hypoxanthine PRTase, orotate PRTase and nicotinate PRTase catalyzed reactions, whereas separation 2 has been employed to define the role that ATP plays in the nicotinamide PRTase-catalyzed reaction along with the allocation of nicotinamide between the reactions catalyzed by nicotinamide PRTase and nicotinamide deamidase.

Kinetic analysis of nicotinate phosphoribosyltransferase from yeast using high pressure liquid chromatography.

A new procedure has been designed for the purification of nicotinate phosphoribosyltransferase and orotate phosphoribosyltransferase from the same baker's yeast extract. Using purified nicotinate phosphoribosyltransferase, the enzyme-catalyzed formation of nicotinate mononucleotide was analyzed using a new high pressure liquid chromatographic assay (Hanna, L., and Sloan, D. L. (1980) Anal. Biochem. 103, 230-234). Initial velocity measurements and product inhibition studies, with pyrophosphate, were performed. In addition, this assay procedure was used to demonstrate that purified nicotinate phosphoribosyltransferase possesses an ATPase activity in the presence of either product (pyrophosphate or nicotinate mononucleotide (NaMN] but in the absence of 5-phosphoribosyl alpha-1-pyrophosphate (P-Rib-PP). Moreover, exchanges of radioactivity between specific substrate/product pairs [( 14C]nicotinate/NaMN and [32P]PPi/P-Rib-PP) in the absence of other substrates were not observed when these pairs were incubated with nicotinate phosphoribosyltransferase, and binding of [14C] nicotinate to nicotinate phosphoribosyltransferase was not detected in the presence of ATP. In contrast, an exchange of label between ATP and [14C]ADP was characterized in the absence of other substrates and in the presence of either P-Rib-PP or PPi. These results indicate that nicotinate phosphoribosyltransferase proceeds through the use of an ordered Uni Uni Bi Ter Ping Pong kinetic mechanism during which ATP reacts with nicotinate phosphoribosyltransferase to form ADP and a previously described phosphorylated enzyme (Kosaka, A., Spivey, H. O., and Gholson, R. K. (1977) Arch. Biochem. Biophys. 179, 334-341). Thereafter, P-Rib-PP and nicotinate bind in order to the active site, to produce PPi and NaMN which are released in a random order followed by Pi. The Km values for ATP, P-Rib-PP, and nicotinate were calculated to be 70 +/- 10, 24 +/- 3, and 23 +/- 4 microM, respectively, whereas a value for Ki(PRPP) of 5 +/- 1 microM was determined.

Early meteorological results from the viking 2 lander.

Early results from the meteorological instruments on the Viking 2 lander are presented. As on lander 1, the daily patterns of temperature, wind, and pressure have been highly repetitive during the early summer period. The average daily maximum temperature was 241 degrees K and the diurnal minimum was 191 degrees K. The wind has a vector mean of 0.7 meter per second from the southeast with a diurnal amplitude of 3 meters per second. Pressure exhibits both diurnal and semidiurnal oscillations, although of substantially smaller amplitude than those of lander 1. Departures from the repetitive diurnal patterns begin to appear on sol 37.

Mars climatology from viking 1 after 20 sols.

The results from the meteorology instruments on the Viking 1 lander are presented for the first 20 sols of operation. The daily patterns of temperature, wind, and pressure have been highly consistent during the period. Hence, these have been assembled into 20-sol composites and analyzed harmonically. Maximum temperature was 241.8 degrees K and minimum 187.2 degrees K. The composite wind vector has a mean diurnal magnitude of 2.4 meters per second with prevailing wind from the south and counterclockwise diurnal rotation. Pressure exhibits diurnal and semidiurnal oscillations. The diurnal is ascribed to a combination of effects, and the semidiurnal appears to be the solar semidiurnal tide. Similarities to Earth are discussed. A major finding is a continual secular decrease in diurnal mean pressure. This is ascribed to carbon dioxide deposition at the south polar cap.

Preliminary meteorological results on Mars from the viking 1 lander.

The results from the meteorology instruments on the Viking 1 lander are presented for the first 4 sols of operation. The instruments are working satisfactorily. Temperatures fluctuated from a low of 188 degrees K to an estimated maximum of 244 degrees K. The mean pressure is 7.65 millibars with a diurnal variation of amplitude 0.1 millibar. Wind speeds averaged over several minutes have ranged from essentially calm to 9 meters per second. Wind directions have exhibited a remarkable regularity which may be associated with nocturnal downslope winds and gravitational oscillations, or to tidal effects of the diurnal pressure wave, or to both.

Changes in esters of fatty acids of Rhizopus arrhizus during germination and growth.

Natural esters of fatty acids of Rhizopus arrhizus Fischer increased during the first 48 hr of growth. During the 48- to 72-hr period, there was a shift in concentration from the methyl esters to the ethyl esters of fatty acids.

The induction of phenylalanine ammonia lyase and phaseollin by 9-aminoacridine and other deoxyribonucleic Acid intercalating compounds.

Bean pod tissue (Phaseolus vulgaris L. var. Top Crop) is induced to produce phaseollin when challenged with various microorganisms. The pods react in the same manner when challenged with 9-aminoacridine. This compound also caused an increase in concentrations of phenylalanine ammonia lyase, an enzyme of the phaseollin synthesizing pathway. Both the synthesis of phenylalanine ammonia lyase and phaseollin are subject to inhibition by actinomycin D, cycloheximide, or 6-methylpurine. The results suggest that both phaseollin production and increased phenylalanine ammonia lyase, when induced by 9-aminoacridine, require newly synthesized RNA and protein.The concentration of 9-aminoacridine optimal for synthesis of phaseollin and PAL (0.5 mg/ml) does not increase the rate of total protein synthesis. However, there is a differential effect of 9-aminoacridine on synthesis of certain protein fractions. Optimal concentrations of 9-aminoacridine induce phaseollin and phenylalanine ammonia lyase synthesis while reducing the net synthesis of RNA during the period of induction.The planar three-ring structure of 9-aminoacridine appears to be a desirable feature for phaseollin and phenylalanine ammonia lyase induction. Similar compounds, all DNA intercalators, having dimethylamino, diethylamino, amino, or 9-alkylamino substitutions of a three-ring acridine skeleton, are also inducers of phenylalanine ammonia lyase and phaseollin synthesis.It is suggested that 9-aminoacridine and other DNA intercalators function as inducers of phaseollin and phenylalanine ammonia lyase synthesis by reacting with the DNA template.