Histamine and cyclic AMP in isolated canine parietal cells.

The relationship between cyclic AMP production and the response of isolated canine parietal cells to histamine has been examined. Histamine increased cyclic AMP generation, and this effect correlated with histamine stimulation of oxygen consumption and aminopyrine accumulation. Metiamide inhibited histamine-stimulated cyclic AMP generation and oxygen consumption in a parallel fashion. At concentrations below 100 microM, isobutyl AMP production and oxygen consumption in a similar fashion. However, with IMX above 100 microM, histamine caused no further increases in oxygen consumption, despite markedly enhanced cyclic AMP generation. Neither carbachol nor gastrin increased cyclic AMP production beyond that produced by IMX alone, and the combinations of histamine and carbachol and of histamine and gastrin produced no greater cyclic AMP generation than produced by histamine. These findings support a close relationship between cyclic AMP production and the action of histamine but not of carbachol or gastrin on isolated parietal cells. The mechanisms underlying the potentiating interactions between histamine, carbachol, and gastrin involve step(s) beyond stimulation of cyclic AMP generation.     

Histamine storage and formation in canine gastric mucosa--effect of pentagastrin stimulation

Histamine storage and formation in the dog gastric mucosa were studied during basal conditions and after pentagastrin stimulation. Histamine formation (histidine decarboxylase activity), histamine content as well as the density of mast cells of the oxyntic gland mucosa were evenly distributed. Histamine content of the mucosa was significantly correlated to the density of mucosal mast cells. In the basal secretory state, histamine formation and histamine content of the oxyntic gland mucosa were of the same magnitude as in the antral mucosa. Pentagastrin stimulation induced a small but significant decrease in histamine content of the oxyntic gland mucosa and a subsequent acceleration in the rate of amine formation. Neither histamine content nor histidine decarboxylase activity of the antral mucosa was affected by pentagastrin infusion.     

血红素氧化酶1可提高脐血间充质干细胞移植梗死心肌细胞的存活率*☆

背景：血红素氧化酶1具有较强的内源性抗氧化作用,可减轻炎症反应,发挥细胞保护作用。 目的：观察血红素氧化酶1对犬脐血间充质干细胞梗死心肌移植后细胞存活率的影响。  方法：取第4代体外培养脐血间充质干细胞,用含氯化高铁血红素的培养液培养24 h,免疫组织化学法检测细胞血红素氧化酶1的表达;将细胞经LacZ报告基因标记后经冠状动脉植入犬心肌梗死区域。 结果与结论：经含氯化高铁血红素培养液培养后的脐血间充质干细胞血红素氧化酶1表达明显上调,并持续2周以上;移植犬梗死心肌区后可长期存活,存活能力明显增强。结果表明氯化高铁血红素可诱导上调犬脐血间充质干细胞血红素氧化酶1的表达,血红素氧化酶1可明显提高脐血间质干细胞梗死心肌移植后的细胞存活率。 关键词：血红素氧化酶1;脐血;间充质干细胞;细胞移植;存活率 doi:10.3969/j.issn.1673-8225.2012.06.017     

Fiber orientation in hypertrophied canine left ventricle.

Myocardial fiber orientation was examined in transmural specimens obtained at the maximum diameter of the left ventricle from five dogs with pressure-overload hypertrophy produced by aortic stenosis, six dogs with volume-overload hypertrophy due to an arteriovenous fistula, and six exercise-hypertrophied greyhounds trained for racing. Hearts arrested in diastole were fixed in situ while the operating end-diastolic pressure was maintained. Fiber orientation changed smoothly from about +60 degrees (with respect to the equator) at the endocardium to about -69 degrees at the epicardium. The majority of fibers near the midwall were oriented circumferentially. These findings are quite similar to those previously reported for normal dogs. In comparison to normals, the left ventricles from dogs with pressure-overload had an increase in longitudinally oriented fibers, i.e. fiber angles between -67.5 degrees and -90 degrees and between +67.5 degrees and +90 degrees; these fibers comprised 10.4 +/- 1.8% of the total fibers in dogs with aortic stenosis vs. 2.9 +/- 1.8% of total fibers in normal dogs (P less than 0.001). Neither the dogs with volume-overload hypertrophy nor exercise-trained animals were significantly different from normals.     

Reconstruction of the microscopic transmural edge of experimentally infarcted canine myocardium

Experimental myocardial infarction of the posterolateral left ventricular wall in 2 dog hearts, the result of 1 h of occlusion of the left circumflex coronary artery followed by 4 days of reperfusion, was studied post mortem by serial histological sectioning. Microscopic examination in a transverse plane showed a zone of apparent necrotic muscle removal which formed a continuous boundary between necrotic and normal myocardium without outlying, detached "islands" of necrosis. Reconstruction of the histological transmural edge of infarction at its interface with viable subepicardial muscle demonstrated wide overlapping and angulated interdigitation of the separated tissues across the midzone of the ventricular wall. The observed 3-dimensional spatial complexity of the transmural infarct boundary may be a limiting factor in successful evaluation of this experimentally important region.     

Reconstruction of the microscopic transmural edge of experimentally infarcted canine myocardium.

Experimental myocardial infarction of the posterolateral left ventricular wall in 2 dog hearts, the result of 1 h of occlusion of the left circumflex coronary artery followed by 4 days of reperfusion, was studied post mortem by serial histological sectioning. Microscopic examination in a transverse plane showed a zone of apparent necrotic muscle removal which formed a continuous boundary between necrotic and normal myocardium without outlying, detached "islands" of necrosis. Reconstruction of the histological transmural edge of infarction at its interface with viable subepicardial muscle demonstrated wide overlapping and angulated interdigitation of the separated tissues across the midzone of the ventricular wall. The observed 3-dimensional spatial complexity of the transmural infarct boundary may be a limiting factor in successful evaluation of this experimentally important region.     

Histamine storage and formation in canine gastric mucosa - effect of pentagastrin stimulation

Histamine storage and formation in the dog gastric mucosa were studied during basal conditions and after pentagastrin stimulation. Histamine formation (histidine decarboxylase activity), histamine content as well as the density of mast cells of the oxyntic gland mucosa were evenly distributed. Histamine content of the mucosa was significantly correlated to the density of mucosal mast cells. In the basal secretory state, histamine formation and histamine content of the oxyntic gland mucosa were of the same magnitude as in the antral mucosa. Pentagastrin stimulation induced a small but significant decrease in histamine content of the oxyntic gland mucosa and a subsequent acceleration in the rate of amine formation. Neither histamine content nor histidine decarboxylase activity of the antral mucosa was affected by pentagastrin infusion.     

Analysis of the isovolumic pressure in the canine left ventricle

Summary Some of the factors which influence the shape of left ventricular isometric pressure are discussed. Complete isometric recordings were obtained in dogs by raising the afterload (aortic pressure) with a special blood pump of own design. The effects of ventricular geometry, myocardial wall thickness and finite velocity of the depolarization wave are discussed. The relation between active state of muscle fibers and isometrically developed pressure in the left ventricle is derived analytically. The commonly used velocity of the contractile element was computed in a new way by differentiation of logarithmically transformed pressure data. This derived function is compared with the simple derivative (dp/dt) with regard to their potential value as indices of myocardial contractility. Contractile element velocity as based on a 3-component model was not found sensitive to so-called contractility changes in the intact heart.     

Circannual rhythm of exercise metabolic rate in humans

Summary Exercise metabolic rate was established by indirect calorimetry in 18 healthy subjects. Each subject was tested every month for 1 year. Four variables demonstrated a circannual rhythm and its acrophases occured in the following months:RQ in October; exercise metabolic rate in April; acceleration of heart rate during exercise in February; percentage of body fat in August.Supported by a grant from the National Institute of Food and Nutrition     

Effect of prednisone on spontaneous canine asthma

This study was designed to investigate the effect of corticosteroids in spontaneous ragweed-sensitive asthmatic dogs. Two animals were treated with prednisone, 40 mg. daily for 3 weeks, and with gradually tapered doses for 6 weeks. The animals were challenged with an aerosol or ragweed extract (RW) before and at intervals during and after drug therapy, and their skin reactivity to the antigen was determined at the same time. The Prausnitz-Küstner (PK) titer and the amount of serum necessary to passively transfer ragweed anaphylaxis to nonatopic dogs were also determined at the same intervals. Treatment of the atopic dogs with corticosteroids completely prevented the ragweed-induced asthma during and for up to 3 months after cessation of therapy. Although the skin reactivity of the atopic dogs was depressed, the PK titer of the sera did not change appreciably during therapy. Increased amounts of serum, however, were necessary to passively sensitize nonatopic dogs for ragweed anaphylaxis for up to 7 months after cessation of drug therapy. The results of the study indicate that corticosteroids can abolish active and passive allergic responses in dogs for as long as 7 months after cessation of the drug, but the mechanism of action is not clear.     

Heart rate and rhythm and intracranial pressure.

Cardiac slowing during elevated intracranial pressure (ICP) could be due to direct activation of central nervous system (CNS) centers or it may be secondary to baroreceptor reflexes activated by the associated pressor response. In five pentobarbital-anesthetized dogs when ICP was raised to 50 mmHg the heart rate decreased 34.4 beats/min (+/-4.8 SE). This cardiac slowing occurred when ICP was elevated after sinoaortic denervation (-24 +/- 4.43 beats/min) and also during elevated ICP when changes in arterial pressure were prevented (-32.3 +/- 4.25 beats/min). These results indicate that the cardiac slowing is largely of CNS origin. In dogs given morphine with pentobarbital to achieve slower heart rates, raising ICP to 50 mmHg by left-sided intracranial balloon inflation led to cardiac dysrhythmias in 9 of 12 dogs. By contrast, raising ICP to 50 mmHg by right-sided intracranial balloon inflation only produced progressive sinus bradycardia. These responses were related to a combined enhancement of vagal and sympathetic activity. Differences observed between right- and left-sides balloon inflation may be partly related to asymmetrical engagement of the cardiac autonomic nerves. The results suggest that left-sided intracranial lesions are more likely to produce cardiac dysrhythmias.     

Mechanoenergetics characterizing oxygen wasting effect of caffeine in canine left ventricle

Caffeine causes a considerable O(2) waste for positive inotropism in myocardium by complex pharmacological mechanisms. However, no quantitative study has yet characterized the mechanoenergetics of caffeine, particularly its O(2) cost of contractility in the E(max)-PVA-VO(2) framework. Here, E(max) is an index of ventricular contractility, PVA is a measure of total mechanical energy generated by ventricular contraction, and VO(2) is O(2) consumption of ventricular contraction. The E(max)-PVA-VO(2) framework proved to be powerful in cardiac mechanoenergetics. We therefore studied the effects of intracoronary caffeine at concentrations lower than 1 mmol/l on left ventricular (LV) E(max) and VO(2) for excitation-contraction (E-C) coupling in the excised cross-circulated canine heart. We enhanced LV E(max) by intracoronary infusion of caffeine after beta-blockade with propranolol and compared this effect with that of calcium. We obtained the relation between LV VO(2) and PVA with E(max) as a parameter. We then calculated the VO(2) for the E-C coupling by subtracting VO(2) under KCl arrest from the PVA-independent (or zero-PVA) VO(2) and the O(2) cost of E(max) as the slope of the E-C coupling VO(2)-E(max) relation. We found that this cost was 40% greater on average for caffeine than for calcium. This result, for the first time, characterized integratively cardiac mechanoenergetics of the O(2) wasting effect of the complex inotropic mechanisms of intracoronary caffeine at concentrations lower than 1 mmol/l in a beating whole heart.     

Immunohistochemical detection of melanoma-specific antigens in spontaneous canine melanoma

Twenty-five formalin-fixed, paraffin wax-embedded canine melanomas were examined immunohistochemically by an immunoperoxidase method to assess their reactivity with three human melanoma-specific monoclonal antibodies (HMB-45, MEL-1, NK1/C3). HMB-45 and MEL-1 reacted with 22/25 (88%) and 18/25 (72%) of canine melanomas, respectively, but only after microwave antigen retrieval and pretreatment with potassium permanganate and oxalic acid (KMnO(4)/OA). Positive reactivity to HMB-45 and MEL-1 was as follows: oral melanomas, 13/16 and 9/16, respectively; cutaneous melanomas, 8/8 and 8/8; melanoma of the digit, 1/1 and 1/1; all pigmented melanomas, 16/18 and 14/18; all amelanotic tumours, 6/7 and 4/7. HMB-45 immunolabelling was characterized by a diffuse granular cytoplasmic pattern within the tumour cells, and MEL-1 labelling by a cytoplasmic pattern with sporadic nuclear localization. In most tumours the labelling was homogeneous, but some showed a multifocal distribution. Generally, a higher percentage of canine melanomas was labelled by HMB-45 than by MEL-1. NK1/C3 failed to label any of seven melanomas tested, regardless of KMnO(4)/OA-pretreatment. Of 16 non-melanocytic tumours (specificity controls), 15 showed no significant reactivity with HMB-45, the exception being one of three plasmacytomas. Immunolabelling by MEL-1 on non-melanocytic tumours was not pursued, due to the poor sensitivity of this antibody as compared with that of HMB-45.     

Identification and characterization of amyloid protein AA in spontaneous canine amyloidosis

Amyloid fibrils were isolated from kidney tissue of a dog that presented with renal failure due to spontaneous amyloidosis. This fibril material was reduced, alkylated and chromatographed on a column of Sepharose CL6B. A major retarded fraction, when subjected to amino acid sequencing, demonstrated a blocked amino terminus. The isolated protein was then degraded with cyanogen bromide, and the resultant three peptides were isolated by high-pressure liquid chromatography. The amino acid sequence of one peptide corresponded to the sequence of human amyloid protein AA from position 17 to 23. A second peptide gave an amino acid sequence homologous to the published human protein AA sequence starting with position 24. Although a high degree of homology between canine and human AA is seen, the blocked amino terminus is similar to the AA protein of mink. These data show that spontaneous canine amyloid is analogous to human reactive (secondary) amyloid and, therefore, may aid in defining mechanisms of human amyloid pathogenesis.     

Histopathological classification and immunophenotyping of spontaneous canine lymphoma in Bangkok metropolitan

The purpose of this study was to examine the immunophenotype of canine lymphomas according to the updated Kiel classification adapted for canine species and to relate the immunophenotype to the anatomical classification, clinical stage, and the malignancy. Forty formalin-fixed embedded tissue sections from dogs affected with lymphoma during 2002–2008 at the Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University were retrospectively studied. Results indicated that the prevalence of canine lymphoma occurred at the average age of 7.6 years old. Of the total 40 samples, 67.5 % (27/40) and 32.5 % (13/40) were found among pure breeds and mixed breeds, respectively. The tumors were classified by anatomical locations: multicentric (25/40, 62.5 %), mediastinal (2/40, 5.0 %), alimentary (2/40, 5.0 %), extranodal (7/40, 17.5 %), and cutaneous (4/40, 10.0 %). The clinical stages are divided as 7.5 % (3/40), 17.5 % (7/40), 17.5 % (7/40), 45.0 % (18/40), and 12.5 % (5/40) in stages I–V, respectively. Histopathology categorization of the lymphomas into low and high grade was accounted for 34 % (17/40) and 46 % (23/40) cases, in that order. Both immunophenotyping cases were 50 % (20/40) of T-cell (CD3 expression) and B-cell (IgM expression) lymphomas. T-cell phenotype showed higher malignancy than B-cell phenotype.     

Morphometry of the coronary microvasculature of the canine left ventricle

The objective of this study was to test for the presence of transmural gradients of various components of the coronary microvasculature of the canine left ventricle. In order to achieve study objectives, the heart and coronary circulation were fixed in a reproducible state of myocardial and vascular tone (diastolic cardiac arrest and maximal coronary vasodilation). Morphometric methods which treat the coronary microvasculature as anisotropically arranged structures were applied for quantitative structural analysis. Eight dog hearts were fixed with a glutaraldehyde-cacodylate-buffered fixative by retrograde perfusion of the aorta with the heart in diastolic arrest and with maximal coronary vasodilation. Tissue samples were taken from areas near to the anterior and posterior papillary muscles from the subendocardium, subepicardium, and intermediate transmural locations. Morphometric results showed a homogeneously arranged array of microvascular and myocardial components with no significant differences in any of the primary morphometric measurements, down to the ultrastructural level, in myocytes relative to transmural location. The results suggest that transmural differences in coronary blood flow are not due to transmural structural differences but rather are due to physiological regulatory mechanisms of coronary blood flow. Further, the results indicate that failure to correct for anisotropy of myocardial structures can lead to erroneous conclusions concerning the structural basis of function in the heart.