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A Varro

Publications and source records attributed to A Varro.

86 records · Page 5Linked to original sources
PubMed1986

Isolation, structure and properties of the C-terminal flanking peptide of preprocholecystokinin from rat brain.

The C-terminal flanking peptide of preprocholecystokinin has been isolated from rat brain. Micro-sequence analysis revealed the primary structure: Ser-Ala-Glu-Asp-Tyr-Glu-Tyr-Pro-Ser. Arylsulphatase and mild acid hydrolysis suggested that both tyrosine residues are sulphated. The peptide was not active in bioassay systems that respond to CCK8; the significance of the conserved tripeptide Ser-Ala-Glu is discussed.

Amino Acid Sequence↗
PubMed1986

Identification of the C-terminal flanking peptide of preprocholecystokinin in rat brain by a novel radioimmunoassay.

The C-terminal flanking peptide of preprocholecystokinin (preproCCK) has been identified in extracts of rat brain using a novel radioimmunoassay. There is a single form of immunoreactive material on gel filtration, ion exchange and reversed-phase HPLC. The C-terminal preproCCK immunoreactivity had a similar pattern of distribution to CCK8 in different regions of rat brain. This assay should help in studies of neuronal CCK biosynthesis.

Animals↗
PubMed1985

Use-dependent effects of amiodarone on Vmax in cardiac Purkinje and ventricular muscle fibers.

Superfusion with 5 micrograms/ml amiodarone for 3-4 h induced use-dependent Vmax block in dog Purkinje and guinea pig ventricular muscle fibers. The recovery from block was exponential with tau of 289 +/- 30 ms in Purkinje (n = 7) and 282 +/- 47 ms in muscle (n = 6) fibers. The onset of frequency-dependent Vmax block was rapid, i.e. reached steady state after 4.2 +/- 0.5 beats (n = 5). The combination of rapid interaction with sodium channel and the reported action potential lengthening make amiodarone unique among Class I antiarrhythmic drugs.

Action Potentials↗
PubMed1985

Cholecystokinin and gastrin forms in the nervous system.

Cholecystokinin octapeptide is the predominant representative of the gastrin-CCK family in the central nervous system. Other forms occur in low concentrations, or restricted locations, as do the gastrins. The pathways of biosynthetic processing can now be studied in detail, following the elucidation of the cDNA sequence for the two peptides. In the vagus both CCK and gastrin can be found. Brain stem neurons receiving an input from gastric mechanoreceptors respond to CCK-8, but most do not respond to gastrin given intravenously or intra-arterially. This system, which may well be involved in mediating the peripheral satiety effect of CCK, is therefore able to distinguish between the two peptides.

Amino Acid Sequence↗
PubMed1985

Effect of antiarrhythmic drugs on the premature action potential duration in canine cardiac Purkinje fibers.

We studied the effect of six class I antiarrhythmic drugs, i.e., quinidine (5 micrograms/ml), disopyramide (10 micrograms/ml), procainamide (30 micrograms/ml), flecainide (4 micrograms/ml), lidocaine (4 micrograms/ml) and mexiletine (4 micrograms/ml), on the durations of the basic action potential (APDb) at a cycle length of 500 ms and on the premature APD (APDt) elicited at progressively increasing diastolic intervals (DI) in canine Purkinje fibers. The difference between APDt elicited at diastolic intervals of 100 msec and the earliest APDt elicited at the onset of effective refractory period was defined as the range of APDt. In control this range was 98 +/- 1.8 ms (n = 59). Disopyramide and procainamide did not change the range significantly but the other four drugs decreased it significantly (P less than .01) as follows: quinidine by 50.2%, lidocaine by 60.2%, mexiletine by 61.6% and flecainide by 61.4%. The following four factors contributed to this decrease in range of APDt: shorter duration of APDb, increased effective refractory period/APD ratio, slower kinetics of APD restitution, and shift of normalized restitution curve toward longer APDt values. The magnitude of the contribution made by each of the above factors varied with different drugs. The greatest contributing factor for quinidine was an increased effective refractory period/APD ratio, for lidocaine a slower restitution and for flecainide and mexiletine the shift of the restitution curve. We concluded that antiarrhythmic drugs belonging to the same class have different effects on the range of premature APD and that these effects cannot be predicted from the effect of the drug on APDb alone.

Action Potentials↗
PubMedDate not supplied

Antibodies to the C-terminus of the cholecystokinin precursor: radioimmunoassay and immunohistochemical studies in adult and developing rat gut.

Antibodies to the extreme C-terminal pentapeptide of procholecystokinin, YEYPS (in the single letter notation), have been used in radioimmunoassay and immunohistochemistry to characterize the material in rat intestine. There is a single major immunoreactive peptide in intestinal extracts that has the properties of the C-terminal tryptic peptide of the CCK precursor. Similar material has previously been found in rat brain. In immunohistochemistry, a population of cells in rat small intestine is revealed, these also contain C-terminal gastrin/CCK activity, but for the most part do not react with gastrin-specific antibodies. During postnatal development their numbers increase considerably. We conclude that the C-terminal flanking peptide of proCCK is a useful marker for sites of CCK production.

Animals↗
PubMedDate not supplied

Frequency-dependent effects of several class I antiarrhythmic drugs on Vmax of action potential upstroke in canine cardiac Purkinje fibers.

Vmax of the action potential upstroke in canine cardiac Purkinje fibers was studied in the presence of seven class I antiarrhythmic drugs--lidocaine (4 micrograms/ml), mexiletine (4 micrograms/ml), propranolol (0.9 micrograms/ml), procainamide (30 micrograms/ml), quinidine (5 micrograms/ml), flecainide (4 micrograms/ml), and disopyramide (3.1 micrograms/ml)--at constant cycle lengths (CCL) and after abrupt changes in cycle length (ACCL). The time constant of Vmax recovery after ACCL at a basic cycle length of 500 ms was 0.09 +/- 0.01 s for lidocaine, 0.18 +/- 0.03 s for mexiletine, 1.35 +/- 0.20 s for propranolol, 4.4 +/- 0.8 s for procainamide, 8.3 +/- 1.2 s for quinidine, 11.0 +/- 0.9 s for flecainide, and 37.9 +/- 9.4 s for disopyramide. These values were similar to those reported by others in guinea pig papillary muscle, and, with the exception of flecainide, conformed to the scheme proposed by Courtney (J Mol Cell Cardiol 1980; 12:1273-86) based on the molecular weight and lipid solubility hypothesis. Each drug altered the Vmax differently at CCL from after ACCL at the same diastolic intervals. The magnitude of these differences and the range of diastolic intervals at which they were present varied among different drugs. These observations explain differences in the drug effects on the Vmax of the regularly and prematurely occurring depolarizations. In the presence of lidocaine and mexiletine, the recovery kinetics of Vmax were not altered by CCL within the 300-1,500-ms range, and the magnitude of Vmax depression was not influenced by action potential duration within the 200-270-ms range.

Action Potentials↗
PubMedDate not supplied

Effect of antiarrhythmic drugs on the cycle length-dependent action potential duration in dog Purkinje and ventricular muscle fibers.

We examined the steady-state action potential duration (APD) within a wide range of cycle lengths (CL) in cardiac dog Purkinje (P) and ventricular (V) muscle fibers in the presence of: lidocaine (L) 4 and 8 micrograms/ml, mexiletine (M) 4 and 8 micrograms/ml, flecainide (F) 1 and 4 micrograms/ml, disopyramide (D) 3.1 and 10 micrograms/ml, quinidine (Q) 2.5, 5, and 10 micrograms/ml, bretylium tosylate (B) 5 and 10 micrograms/ml, and sotalol (S) 5 micrograms/ml. In the P fibers, all drugs except for B and S shortened plateau duration, increased slope of phase 2 and decreased slope of phase 3 repolarization, and either shortened (L, M, Q, F) or prolonged (D) APD. B and S lengthened APD and did not change significantly the slopes of phase 2 and 3 of repolarization. Each drug altered the relation between APD and Cl according to one of the following three patterns: (a) L, M, Q, and F shortened APD more at long than at short CL; (b) D lengthened APD more at short than at long CL; (c) B and S lengthened APD more at long that at short CL. In the V fibers, APD was lengthened by F, Q, and B, and shortened by L and M. The drug-induced changes in the relation between APD and CL were as in the P fibers. The results suggest that the drug-induced changes in the relation between APD and CL can be predicted from the drug effects on the course of repolarization.

Action Potentials↗
PubMedDate not supplied

[Death caused by sharp injury. Criminologic and criminalistic aspects].

From 3497 obductions during the ten years between 1979 and 1988 100 homicides and 18 suicides were caused by sharp trauma. Homicide by sharp trauma is the most frequent method for killing. These 100 homicides were analysed in relation to the age and nationality of victims and perpetrators, place of action, number and localisation of wounds, cause of death. The main results are discussed, particularly those which vary from the results of other authors.

Adolescent↗
PubMedDate not supplied

[Preservation of stab and cut wounds of the skin].

The authors compare different methods of fixation of stab and cut wounds of the skin. Fixation in formalin has more disadvantages than advantages despite its vast application. In our opinion fixation in formalin-free solution leads to better results especially with regard to subsequent investigations carried out later on. The best results were found with a modification of the Dietrich-Ratnewski fixing solution. This contains acetic acid, absolute alcohol, glycerin and water in the volume ratios 10: 15: 5: 70.

Fixatives↗
PubMedDate not supplied

[Roentgen imaging of stab wounds in parenchymatous organs].

Stab wounds were made in parenchymatous organs (e.g. liver, spleen, kidneys, lungs) using a variety of instruments. The shape of the resulting canal was investigated by X-ray analysis after introduction of an X-ray contrast medium. The best contrast was obtained using a contrast medium containing barium. The shape of the canal gave a direct representation of the outline of the instrument used. The width of the canal was however, always several millimeters smaller than the corresponding blade of the instrument. The position of the blade back in single-edged blades could be demonstrated with stronger contrast.

Contrast Media↗