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Biomedical subjects

T Imada

Publications and source records attributed to T Imada.

At least 127 records · Page 7Linked to original sources
PubMed1989

Detection of reactivating pseudorabies virus in tissue by immunoperoxidase technique.

Reactivation of pseudorabies virus (PRV) was induced in pigs by prednisolone treatment. The virus was re-isolated from nasal secretions of four, brain cortex of two and mandibular lymph node of three out of 12 pigs, respectively. The characteristic lesion of recurrently infected pigs was focal necrosis in the brain cortex and mandibular lymph node, accompanied by reactivating virus particles in the degenerating cells. Coincident with the pathological lesions, PRV antigen was detected in two of the brain cortex and six of the mandibular lymph node specimens by immunoperoxidase staining. These results suggest that the immunoperoxidase technique was more sensitive than virus isolation for demonstrating the reactivity of PRV in recurrently infected pigs.

Animals↗
PubMed1989

Role of endogenous atrial natriuretic peptide in congestive heart failure.

Effects of purified rabbit anti-rat 25-amino acid atrial natriuretic peptide (ANP) immunoglobulin G (IgG) on renal sodium excretion and glomerular filtration rate were studied in a rat model of congestive heart failure (CHF) having high circulating ANP levels. Bolus injection of anti-ANP into anesthetized rats with surgically induced myocardial infarction (MI) significantly and markedly depressed both absolute and fractional urinary excretion of sodium without affecting mean arterial pressure or glomerular filtration rate. By contrast, anti-ANP failed to affect these renal functions in normal or acutely water-deprived rats. Nonimmune IgG did not affect renal function in MI rats. These results indicate that high circulating ANP plays an important role in sodium homeostasis of congestive heart failure: by promoting sodium excretion, ANP opposes the tendency of sodium retention characteristic of CHF.

Animals↗
PubMed1989

Clearance of atrial natriuretic factor by lung, liver, and kidney in human subjects and the dog.

We determined human and canine plasma clearance of atrial natriuretic factor (ANF) by lung, liver, and kidney from arteriovenous differences in plasma ANF and measured organ plasma flow. Human subjects had lower plasma ANF concentrations in the pulmonary vein or the pulmonary capillary wedge position when compared with the pulmonary artery, and both sites yielded pulmonary ANF extraction ratios of 24%. Canine lung ANF extraction was 19 +/- 3% and pulmonary ANF clearance was 328 +/- 78 ml/min per m2 vs. 357 +/- 53 ml/min per m2 in man. Hepatic plasma ANF clearance was 216 +/- 26 ml/min with an extraction ratio of 30 +/- 3% in humans and 199 +/- 89 ml/min and 36 +/- 6% in the dog. Renal plasma ANF clearance in human subjects was 78 +/- 12 ml/min per kidney and correlated well with each kidney's creatinine clearance (r = 0.58, P less than 0.05). The mean renal ANF extraction ratio was 35 +/- 4% in human subjects and 42 +/- 6% in the dog. These data quantitate the specific organ ANF clearances by lung, liver, and kidney in human subjects and in dogs and provide a rationale for elevated plasma ANF levels in cirrhosis, renal failure, and diseases accompanied by reduced perfusion of these organs. These findings support the conclusion that plasma ANF concentrations are dependent upon both the stimuli for ANF secretion as well as the specific organ clearances of ANF.

Adolescent↗
PubMed1989

Evaluation of the pathogenicity and immunogenicity of vaccinia virus to piglets.

The pathogenicity and immunogenicity of vaccinia virus were examined in order to evaluate the possibility of its application as a recombinant viral vaccine in pigs. Following scarification inoculation with vaccinia virus, a mild reddish papulation developed only on the scarified part of the skin. No symptoms of illness such as fever or stunting were noted. Vaccinia virus was recovered in titers from scarified skin 4 and 7 days after inoculation. Control piglets cohabited with inoculated animals remained normal for the whole 5 week observation period. Hemagglutination inhibition and indirect immunofluorescence tests detected antibodies against vaccinia virus in the inoculated piglets, whereas no anti-vaccinia virus antibodies were detected in the contact control animals. Antigen-induced blastogenic tests of peripheral blood lymphocytes from animals, revealed that lymphocytes obtained from inoculated donors 5 weeks after inoculation, had a higher stimulation index (P less than 0.05) than did those from uninoculated piglets. These results suggested that vaccinia virus would be useful as a recombinant viral vector for pigs.

Animals↗
PubMed1989

Immunohistologic study of pulmonary and lymphatic tissues from gnotobiotic pigs inoculated with ara-T-resistant strain of pseudorabies virus.

Ara-T-resistant strain of pseudorabies virus (PRV) was inoculated intranasally into six 2-week-old gnotobiotic pigs. Five inoculated pigs were sneezing and coughing. In pigs 1 to 4 killed on postinoculation days (PID) 3, 5, 7, and 9, respectively, PRV antigen was detected in respiratory epithelial cells, and pigs had severe pneumonitis. In pigs 5 and 6 killed on PID 11 and 13, respectively, PRV antigen was localized in macrophages in alveoli and necrotizing nodules. Immunoglobulin-containing cells (IgG, IgM, and IgA) were detected first in pneumonic lesions in pig 4 killed on PID 9. Detection of immunoglobulin-containing cells was coincident with pulmonary inflammation and regeneration of pneumonic lesions. The number of IgG-containing cells was greater than that of IgM- and IgA-containing cells. Corresponding to transient viral multiplication, IgG-, IgM-, and IgA-containing cells were demonstrated first in lymphatic tissues in pig 1 killed on PID 3 and their number was 5 to 10 times more than those in control pigs 7 and 8. Seemingly, PRV replication in lymphatic tissues stimulated the proliferative response of specific immunoglobulin-producing cells, and the appearance of immunoglobulin-containing cells in the lungs was associated with clearance of PRV and regeneration of pneumonic lesions.

Animals↗
PubMed1988

Atrioactivase, a specific peptidase in bovine atria for the processing of pro-atrial natriuretic factor. Purification and characterization.

A seryl protease which catalyzes conversion of proatrial natriuretic factor (ANF) to the active circulating form, ANF(99-126), was purified from a particulate fraction of bovine atria. The enzyme was solubilized with 1.6 M KCl. The molecular mass of the purified enzyme was 580 kDa on gel filtration, whereas by sodium dodecyl sulfate-polyacrylamide gel electrophoresis a cluster of six bands with molecular masses around 30 kDa was observed. The purified enzyme produced ANF(99-126) from partially purified bovine pro-ANF by the selective cleavage of the arginyl peptide bond in the -Pro97-Arg98-Ser99-sequence in pro-ANF. The enzyme was localized mainly in the microsomal fraction rather than the granule fraction. It is likely that the enzyme selectively cleaves the Arg98-Ser99 peptide bond in pro-ANF during the process of secretion.

Animals↗
PubMed1988

Plasma human atrial natriuretic factor in cirrhosis and ascites with and without functional renal failure.

Functional renal failure of cirrhosis (FRFC) is a usually fatal syndrome of acute renal failure occurring in patients with advanced liver disease. Although not conclusively proven, most evidence suggests that renal arterial and arteriolar vasoconstriction is the cause of the renal failure in these patients. However, the mediators of the vasoconstriction remain unknown. Human atrial natriuretic factor (hANF) is a hormone with potent natriuretic, diuretic, and vasorelaxant properties. A deficiency of hANF could lead to renal arterial vasoconstriction and avid renal sodium retention as seen in FRFC. This study was undertaken to determine if patients with FRFC are deficient in circulating hANF. Seven patients with advanced alcoholic liver disease and renal failure of unknown cause (FRFC) were compared with 7 patients with advanced alcoholic liver disease, ascites, and normal serum creatinine as well as with 14 healthy volunteers. Plasma hANF was measured by radioimmunoassay. Plasma hANF was 742 +/- 227 pg/ml (mean +/- SEM) in patients with FRFC compared with 360 +/- 70 pg/ml in patients with liver disease and normal serum creatinine (p greater than 0.05) and 28 +/- 5.7 pg/ml in healthy volunteers (p less than 0.005 vs. FRFC and chronic liver disease, ascites, and normal serum creatinine). Thus, FRFC is not caused by a deficiency of circulating hANF. The elevated plasma hANF levels in patients with chronic liver disease and continued sodium retention may suggest a renal insensitivity to the natriuretic effects of hANF.

Adult↗
PubMed1988

[Carcinoma of Papilla Vater with celiac axis stenosis--application of percutaneous transluminal angioplasty].

In a case of carcinoma of Papilla of Vater with angiographically proved celiac axis stenosis, PTA (Percutaneous transluminal angioplasty) was performed to restore sufficient blood flow, followed by standard pancreaticoduodenectomy. This would be the first case to have PTA applied to the cancer-bearing celiac axis stenosis. The patient was 58 year old female, presented with acute abdominal pain and vomiting. DIC revealing protruding defect in the choledochus and hypotonic duodenography showed elevated tumor at Papilla of Vater. Aortography revealed 75% circumferential stenosis at the celiac artery and superior mesenteric angiography visualized all the branches of the celiac axis via dilated pancreaticoduodenal arcades. PTA with Grüntzig Dilaca (4.3Fr), 5 atm for 60 seconds serially every two min for 4 times was performed with the immediate relief of the stenosis down to 25%. Intraoperatively 70-80ml/sec flow confirmed, pancreaticoduodenectomy was done without sacrificing curability. PTA would be superior strategy to restore sufficient blood flow in cases with GI anastomoses, compared with other bypass or reimplantation surgery.

Ampulla of Vater↗
PubMed1988

Purification of a specific peptidase in bovine atria for the processing of pro-atrial natriuretic factor.

A serine protease which catalyses the conversion of the precursor of ANF (atrial natriuretic factor) to the active circulating form, ANF-(99-126)-octacosapeptide, was purified from a particulate fraction of bovine atria. The enzyme was solubilized with a buffer containing 1.6M KCl. The molecular mass of the purified enzyme was 580 kDa on gel filtration, whereas on sodium dodecyl sulfate-polyacrylamide gel electrophoresis a cluster of six bands with molecular masses around 30 kDa was observed. The purified enzyme produced the ANF-(99-126)-octacosapeptide from partially purified bovine pro-ANF by the selective cleavage of the arginyl peptide bond in the -Pro97-Arg98-Ser99-sequence in pro-ANF. It is likely that the enzyme selectively cleaves the Arg98-Ser99 peptide bond in pro-ANF when ANF is secreted into the circulation.

Animals↗
PubMed1988

[Effects of OK-432 on UFT activation].

An experiment to gauge the effect of OK-432 on UFT activation under a combined administration of UFT and OK-432 at a therapeutic dose has been pursued clinically by determining the blood and intratumoral 5-FU concentrations after administration of UFT. UFT was administered orally to a group of AH-130-bearing rats at a dose of 12 mg/kg or 8 mg/kg. In another group that was given combined treatment with OK-432, the OK-432 was administered subcutaneously at a dose of 0.1 KE/kg together with UFT. The intratumoral 5-FU concentration at 4 hours after UFT 12 mg/kg administration showed higher values in th single UFT treated group than in the combined treated group, but at 8 hours no significant difference was found between these two groups as the concentrations were 0.133 +/- 0.027 microgram/g and 0.128 +/- 0.021 microgram/g, respectively. Further, no significant differences were noticed in the blood and intratumoral 5-FU concentrations between both groups after administration of UFT at a dose of 8 mg/kg. Clinically, the blood FT-207 and 5-FU concentrations after UFT administration showed no significant difference between the single UFT treated group and the combined OK-432 treated group, nor was there a significant difference in the intratumoral concentration. In summary, it is considered that OK-432 has little effect on UFT activation when UFT and OK-432 are administered in combination.

Administration, Oral↗
PubMed1988

[Lymphatic flow of the remnant stomach].

Aiming at establishing an appropriate lymph node dissection for carcinoma of the remnant stomach and of the lower esophageal carcinoma in the status post-gastrectomy, lymphatic flow was investigated clinically as well as experimentally. Nineteen cases of carcinoma of the remnant stomach and 8 cases of esophageal carcinoma after partial gastrectomy were studied. Lymph node metastasis of the remnant stomach carcinoma were more frequently seen at perigastrium, splenic hilum, and along splenic artery. Those further extended to para-aortic and diaphragmatic nodes. Three cases of lower esophageal carcinoma after gastrectomy had massive nodal involvement at perigastrium, as well as intra-thoracic lymph nodes. Experimentally 5-Fu emulsion was injected submucosally under endoscope in 25 dogs and subserosally in 6 rabbits. 5-Fu contents in lymph nodes were measured 30 minutes after injection. The most prominent difference in lymphatic flow from the remnant stomach was increase in ascending flow into intrathoracic lymph nodes through para-aorta. This increment was seen irrespective of Billroth I or II anastomosis. On the contrary, descending lymphatic flow from the lower esophagus into the intra-abdominal lymph nodes was not disturbed by gastrectomy. Cardiac lymph node dissection in rabbits accelerated ascending flow. Those results would indicate the necessity of complete block of ascending flow in cases of the remnant stomach carcinoma and of intra-abdominal lymph node dissection in those of the lower esophageal carcinoma after gastrectomy.

Aged↗
PubMed1987

Direct release of angiotensins I and II from isolated rat kidney perfused with angiotensinogen-free medium.

A direct measurement of both angiotensins I and II immunoreactive substances was made in the perfusate from isolated rat kidney perfused with Krebs-Ringer solution which was free of any component of the renin-angiotensin system. The identity of the immunoreactive peptides was confirmed as angiotensin I and angiotensin II by high-pressure liquid chromatography in reference to standard compounds. The rate of release of angiotensins was as high as 1313.5 +/- 184.5 and 772.4 +/- 82.5 pg for angiotensins I and II, respectively, during the first perfusion period of 20 min, and it remained stable at least for 2 hours. There was a good relationship between the angiotensin I secretion rate and renin secretion rate simultaneously determined in the perfusate, and also between the angiotensin I secretion rate and angiotensin II secretion rate. These results taken together with the previous observations of the coexistence of renin and angiotensins I and II in juxtaglomerular cells of the kidney provide evidence for intrarenal formation and release of angiotensin II. It does not agree with the notion that these peptides are internalized from circulation. Angiotensin II secreted from the kidney may play diverse functions in intrarenal regulation.

Angiotensin I↗
PubMed1987

Two distinct forms of receptors for atrial natriuretic factor in bovine adrenocortical cells. Purification, ligand binding, and peptide mapping.

The atrial natriuretic factor (ANF) receptor of bovine adrenal cortex was solubilized with Triton X-100 and purified by sequential chromatography on ANF-(99-126)-agarose, GTP-agarose, and wheat germ agglutinin-Sepharose. Two subtypes of ANF receptors were isolated, both of which showed specific ANF binding, whereas one of the ANF receptor subtypes also possessed significant cyclase activity. Both of the receptors showed high capacities (Bmax = 5.7-6.8 nmol/mg of protein) and high affinities (Kd = 54-68 pM) for ANF-(99-126). The cyclase-free receptor had high affinity (Ki = 150-220 pM) to C-terminal truncated ANF analogs, whereas the cyclase-containing receptor had a much weaker affinity (Ki = 10(6)-10(7) pM). When treated with dithiothreitol, the purified cyclase-containing and cyclase-free ANF receptors migrated as a single band at Mr 135,000 and 62,000, respectively, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified cyclase-free receptor is not a product derived from the cyclase-containing receptor because (i) two proteins with Mr of 135,000 and 62,000 were specifically labeled with 4-azidobenzoyl 125I-ANF-(102-126) in nonsolubilized intact membranes; (ii) the truncated ANF analogs (10(4) pM) prevented the photolabeling of the 62,000-dalton protein but not that of the 135,000-dalton protein; and (iii) two-dimensional peptide mapping showed more than 90% difference between the profiles of the two purified ANF receptor subtypes. This study provides first direct evidence for the existence of two distinct ANF receptors which are different not only in their pharmacological properties but also in their primary structure.

Adrenal Cortex↗
PubMed1987

Purification and characterization of two types of atrial natriuretic factor receptors from bovine adrenal cortex: guanylate cyclase-linked and cyclase-free receptors.

Atrial natriuretic factor (ANF) receptors with and without guanylate cyclase activity were simultaneously purified to apparent homogeneity from bovine adrenal zona glomerulosa cell membrane fractions. The particulate guanylate cyclase which co-purified with the ANF receptor showed one of the highest specific activity reported. The receptors with or without the guanylate cyclase activity showed high affinities to ANF (99-126). The receptor without the cyclase showed a high affinity to truncated ANF analogs, ANF (103-123) and ANF (105-121), whereas the cyclase-linked receptor had a much lower affinity to these analogs. Both of the receptors migrated as a single band with a molecular weight of 135,000 daltons on SDS-gel electrophoresis under non-reducing conditions. The 135,000 daltons band of the receptor without the cyclase was shifted to a 62,000 daltons band under reducing conditions, but the band for the cyclase-linked receptor was not shifted. These results demonstrated the presence of two subtypes of ANF receptor in bovine adrenal cortex and indicate two different modes of intracellular action of ANF.

Adrenal Cortex↗
PubMed1987

Identification of a peptidase which processes atrial natriuretic factor precursor to its active form with 28 amino acid residues in particulate fractions of rat atrial homogenate.

With the objective of identifying specific peptidase responsible for the processing of atrial natriuretic factor precursor pro-ANF to the circulating active form ANF (99-126), a fluorometric assay method was devised using synthetic fluorogenic substrate Boc-Ala-Gly-Pro-Arg-MCA(methylcoumarinamide) which contains the amino acid sequence immediately adjacent to the arginyl peptide bond which is cleaved in the natural processing of pro-ANF. A protease which selectively cleaves this bond and produces the natural circulating peptide was identified in the particulate fraction of rat atrial homogenate and was solubilized by 1.6 M KCl. It was partially purified by affinity chromatography heparin-agarose column and was shown to be a serine protease. Its reaction product with natural pro-ANF was identified as ANF (99-126) containing 28 amino acid residues.

Animals↗
PubMed1987

Synthesis and presence of atrial natriuretic factor in rat ventricle.

Rat heart ventricles contained immunoreactive atrial natriuretic factor (irANF) and mRNA for ANF. The size of ANF mRNA in the ventricle was identical with that of the atria. High performance gel filtration chromatography showed that 84% of ventricular irANF elutes at a position corresponding to the low molecular weight form of ANF (99-126) and 16% of irANF elutes at a position corresponding to the precursor form of ANF. The irANF content of the ventricles of spontaneously hypertensive rats was 3 times as much as that of Wistar Kyoto rats. These results suggest that ventricle synthesizes ANF in response to hypertension and processes in a manner different from that in atria.

Animals↗
PubMed1987

Pathological changes in HPCD pigs with prednisolone induced recrudescence of pseudorabies virus.

In HPCD pigs inoculated with PRV, latent PRV could be reactivated in-vivo by the administration of large doses of prednisolone 3 months after the primary infection. In two pigs, virus shedding was without clinical signs of disease, whereas depression of circulating lymphocytes was prominent. Reactivation of PRV was also demonstrated by cultivation of the brain cortex on the 7th day and the mandibular lymph node on the 9th day after the prednisolone began treatment. Coincident with the virus isolation, characteristic lesions were observed in 2 pigs in the central nervous tissues and mandibular lymph nodes and these were composed of cell necrosis and eosinophilic intranuclear inclusion bodies. Cells containing the intranuclear inclusion bodies had immature and mature PRV particles. Results of the present study with HPCD pigs indicated that the lesions in the brain and lymph node accompanied by eosinophilic intranuclear inclusion bodies were pathogonomonic lesions induced by reactivation of PRV.

Animals↗