Biomedical subjects

H Akashi

Publications and source records attributed to H Akashi.

At least 109 records · Page 6Linked to original sources

PubMed1995

Inferring weak selection from patterns of polymorphism and divergence at "silent" sites in Drosophila DNA.

Patterns of codon usage and "silent" DNA divergence suggest that natural selection discriminates among synonymous codons in Drosophila. "Preferred" codons are consistently found in higher frequencies within their synonymous families in Drosophila melanogaster genes. This suggests a simple model of silent DNA evolution where natural selection favors mutations from unpreferred to preferred codons (preferred changes). Changes in the opposite direction, from preferred to unpreferred synonymous codons (unpreferred changes), are selected against. Here, selection on synonymous DNA mutations is investigated by comparing the evolutionary dynamics of these two categories of silent DNA changes. Sequences from outgroups are used to determine the direction of synonymous DNA changes within and between D. melanogaster and Drosophila simulans for five genes. Population genetics theory shows that differences in the fitness effect of mutations can be inferred from the comparison of ratios of polymorphism to divergence. Unpreferred changes show a significantly higher ratio of polymorphism to divergence than preferred changes in the D. simulans lineage, confirming the action of selection at silent sites. An excess of unpreferred fixations in 28 genes suggests a relaxation of selection on synonymous mutations in D. melanogaster. Estimates of selection coefficients for synonymous mutations (3.6 < magnitude of Nes < 1.3) in D. simulans are consistent with the reduced efficacy of natural selection (magnitude of Nes < 1) in the three- to sixfold smaller effective population size of D. melanogaster. Synonymous DNA changes appear to be a prevalent class of weakly selected mutations in Drosophila.

Animals↗

PubMed1995

Total aortic replacement in a patient with mega aorta syndrome--a case report.

A 64-year-old woman without manifestations of Marfan syndrome was referred for the close investigation of a pulsatile abdominal mass. Computed tomographic scans and magnetic resonance images revealed aneurysmal dilatation of the entire aorta, including the ascending aorta and extending to the bifurcation of the aorta, as well as tortuousness of the thoracoabdominal and abdominal aorta. Digital subtraction angiography also showed aneurysmal dilatation of the entire aorta and trivial aortic regurgitation. However, aortic annular dilatation was not found by echocardiography or aortography. The entire aorta was replaced in two stages. First, graft replacement of the ascending aorta, except for the sinus segment, and the aortic arch was performed using an elephant trunk technique under hypothermic cardiopulmonary bypass with selective cerebral perfusion. Twelve weeks later, the remaining aorta, including the descending aorta and extending to the common iliac artery on the right side, and to the common femoral artery on the left side, was replaced with a partial cardiopulmonary bypass using femoral artery and vein cannulation. We believe that patients with mega aorta syndrome are best treated by total aortic replacement. The results in the present case indicate that the elephant trunk technique is useful for extensive aortic replacement in stages, and greatly facilitates the second stage operative procedures.

Aorta↗

PubMed1995

Isolation of a serotype G6P11 bovine rotavirus showing two-way cross-neutralization with the serotype G10P11 virus.

Four stains designated as OB94-1 to OB94-4 of group A bovine rotavirus (BRV) were isolated from 35 fecal samples of calves with diarrhea in sporadic outbreaks. In VP7 (G) and VP4 (P) serotyping of these isolates, OB94-1 to OB94-3 were determined as G6P5, G6P5 and G10P5, respectively, by cross neutralization (NT) test and the G- and P- serotyping polymerase chain reaction (PCR) analysis. OB94-4 showed a one-way antigenic relation with the Lincoln stain (G6P1) and a weak antigenic relationship with the KK3 strain (G10P11), and was determined as G6P11 by the PCR method. Thus, OB94-4 was shown to be a new G6 BRV with different antigenic properties from the others in the NT test.

Animals↗

PubMed1995

[Simultaneous operation for annulo-aortic ectasia, mitral regurgitation, and tricuspid regurgitation in a patient with Marfan syndrome--report of a case].

A 57-year-old man with manifestations of Marfan syndrome was referred for detail examination of cardiac murmur to our hospital. Cardioangiography showed moderate aortic valve regurgitation (2/4), and severe mitral valve regurgitation (3/4), in addition to aneurysmal dilatation of the aortic root. Moderate tricuspid valve regurgitation (2/4) was also detected by Doppler echocardiography. Aortic root replacement with the Cabrol technique, mitral valve replacement with a St. Jude Medical valve, and repair of the tricuspid valve with the bicuspidalization technique were simultaneously performed in this patient. His postoperative recovery was uneventful. In this study, we discuss about the indications of simultaneous aortic root replacement and mitral valve replacement in a patient with Marfan syndrome.

Aorta↗

PubMed1994

Aortic root replacement with a composite graft: results of 69 operations in 66 patients.

Between December 1973 and December 1992, 66 patients underwent aortic root replacement at our hospital. The mean age of the patients was 42.5 years (range, 20 to 71 years); 44 patients were male and 22 were female. Of the 66 patients, 34 (51.5%) had clinical stigmata of Marfan's syndrome. The aortic pathology requiring aortic root replacement was annuloaortic ectasia in 59 patients, aortic dissection in 5, and progressive dilatation of the ascending aorta after aortic valve replacement in 2. Twelve of the 59 patients with annuloaortic ectasia also had aortic dissection. The operative techniques used were the Bentall technique in 36 operations, the Cabrol technique in 21, the aortic button technique in 3, and other miscellaneous techniques in 9. The hospital mortality rate for the primary operation was 10.6% (7 patients), and the late mortality rate was 20.3% (12 patients). Four of the late deaths were related to the graft valve prosthesis, and 6 were related to the progression of aneurysmal diseases on the remaining aorta. The survival rate was 71.0% at 10 years. Pseudoaneurysm at the suture lines was detected in 7 patients, 6 of whom had been treated with the Bentall technique, and 5 patients also had Marfan's syndrome. No patients having aortic root replacement with the Cabrol technique have required reoperation for pseudoaneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1994

Surgical treatment for acute aortic dissection and coexistent degenerative aortic aneurysm. Report of three cases.

Acute aortic dissection occurring in an aorta previously afflicted with degenerative, atherosclerotic is unusual. We report three cases with acute aortic dissection (DeBakey type III-b) occurring in an aorta which had a preexistent degenerative aortic aneurysm. Two of the three patients had acute aortic dissection originating from the distal end of the degenerative aneurysm, and the remaining one had the acute aortic dissection and degenerative aneurysm at different segments of the aorta. Since the risk of rupture is likely to be much higher in the patients with coexistence of acute aortic dissection and degenerative aortic aneurysm, compared with patients with DeBakey type III acute aortic dissection alone, we believe that a prompt and aggressive surgical approach is essential to prevent rupture, and that digital subtraction angiography (DSA) is more helpful in making a correct diagnosis and in helping to decide surgical procedures and supportive methods than other noninvasive diagnostic procedures.

Acute Disease↗

PubMed1994

False aneurysm of the ascending aorta with fistula to the right atrium. Noninvasive diagnosis by computed tomographic scan and two-dimensional echocardiography with successful repair.

A 57-year-old Japanese man presented with symptoms of congestive heart failure 9 years after aortic valve replacement. On auscultation, a continuous murmur was heard at the left lower sternal border. Chest radiograph showed moderate cardiomegaly and a widened upper mediastinum. Computed tomographic scans showed a dilated ascending aorta, in which there was no intimal flap, and also showed a large mass which compressed the right atrium. Two-dimensional Doppler echocardiography revealed abnormal continuous blood flow directed from the dilated ascending aorta to the right atrium and no periprosthetic leak. At operation, a false aneurysm of the ascending aorta which originated from the aortotomy suture line and a fistula from the aorta to the right atrium were confirmed. The fistula was closed with pledgeted sutures, and the ascending aorta was replaced with a collagen-coated double woven velour dacron graft. The patient recovered uneventfully. Computed tomographic scan and two-dimensional echocardiography are complementary techniques for reliable non-invasive assessment of the complexity of an aortic aneurysm.

Aneurysm, False↗

PubMed1994

Surgical treatment of aneurysms of the aortic arch using a simplified selective cerebral perfusion technique.

Between April 1989 and October 1993, 35 patients underwent aortic arch reconstruction for aneurysms using cardiopulmonary bypass (CPB) with selective cerebral perfusion (SCP). Of the 35 patients, the initial 19 (Group P) consecutively received simplified SCP (partial brachiocephalic perfusion; PBP), and the next 16 (Group S) were consecutively treated with standard SCP. For cerebral protection, blood was supplied to the right axillary artery in Group P, and to the right axillary and the left common carotid arteries in Group S. The aneurysms was aortic dissection in 24 patients, and was secondary to arteriosclerosis in the remaining 11. Partial replacement of the aortic arch together with the ascending aorta was the most commonly performed procedure in both groups. The cardiopulmonary bypass time and the cardiac arrest time were not significantly different between the two groups. The overall cerebral perfusion time was significantly longer in Group S (100 min) than in Group P (65 min); however, when 2 patients with an accidental prolongation of the cerebral perfusion time in Group S were excluded, there was no significant difference in the cerebral perfusion time between the two groups. Early death occurred in 3 patients (15.8%) in Group P, and 2 patients (12.5%) in Group S, however, there were no deaths related to the selective cerebral perfusion technique, and there were no late deaths in either group. Cerebral complications were seen in 1 patient in each group (6.3% vs. 6.7%, not significant). These results suggest that the simplified SCP (PBP) under hypothermic CPB provides as satisfactory cerebral protection as standard SCP, so long as the patency of the circle of Willis is confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Synonymous codon usage in Drosophila melanogaster: natural selection and translational accuracy.

I present evidence that natural selection biases synonymous codon usage to enhance the accuracy of protein synthesis in Drosophila melanogaster. Since the fitness cost of a translational misincorporation will depend on how the amino acid substitution affects protein function, selection for translational accuracy predicts an association between codon usage in DNA and functional constraint at the protein level. The frequency of preferred codons is significantly higher at codons conserved for amino acids than at nonconserved codons in 38 genes compared between D. melanogaster and Drosophila virilis or Drosophila pseudoobscura (Z = 5.93, P < 10(-6)). Preferred codon usage is also significantly higher in putative zinc-finger and homeodomain regions than in the rest of 28 D. melanogaster transcription factor encoding genes (Z = 8.38, P < 10(-6)). Mutational alternatives (within-gene differences in mutation rates, amino acid changes altering codon preference states, and doublet mutations at adjacent bases) do not appear to explain this association between synonymous codon usage and amino acid constraint.

Animals↗

PubMed1994

Inhibition of trypsin, plasmin, thrombin and kallikrein by various esters of guanidino- and amidino-acids.

Inhibitory effects of various phenolic esters of trans-4-guanidinomethylcyclohexanecarboxylic acid, amidino-piperidine-4-alkanoic acids or trans-4-amidinocyclohexane-4-alkanoic acids on trypsin, thrombin, plasmin and pancreatic kallikrein were examined. Their inhibitory effects were strongly affected by the acid portion and phenolic group constituting the esters. The effects of the acidic portion and phenolic group on the inhibitory effect varied with each protease; they were most effective on thrombin and plasmin and least effective on kallikrein. The inhibitory effect of these esters on trypsin was affected mainly by acid portion.

Amidines↗

PubMed1994

Partial purification of a trypsin-like proteinase in platelets.

Among various fluorogenic substrates for trypsin-like proteinases, tert-butyloxycarbonyl-L-valyl-L-prolyl-L-arginine 4-methylcoumarin-7-amide was strongly hydrolyzed by a crude extract of rabbit platelets. The proteinase was partially purified (92-fold) from rabbit platelets by successive chromatographic separations on phenyl-Sepharose CL-4B, L-arginine-Sepharose 4B and Sephadex G-200 columns. Its molecular mass was found to be greater than 200 kDa by analytical gel filtration and its optimal pH was approximately 9. The proteinase activity was strongly inhibited by diisopropylfluorophosphate, phenylmethanesulfonyl fluoride, tosyl-L-lysine chrolomethyl ketone, leupeptin, p-nitrophenyl-p-guanidinobenzoate, and also by the 2,4-dimethylphenyl ester of amidinopiperidine-4-propionic acid and the 4-tert-butylphenyl ester of trans-4-guanidinomethylcyclohexanecarboxylic acid which strongly inhibit platelet aggregation induced by various stimuli.

Amino Acid Sequence↗

PubMed1994

Genetic heterogeneity of Helicobacter pylori by pulse-field gel electrophoresis and re-evaluation of DNA homology.

PURPOSE: The genetic heterogeneity of Helicobacter pylori isolates was re-evaluated by using pulse-field gel electrophoresis to examine macrorestriction patterns and by studying DNA homology. MATERIALS AND METHODS: Twenty H. pylori isolates, two closely related species, H. mustelae and H. felis, and Campylobacter spp. were used. Notl-digested macrorestriction patterns were examined by pulse-field gel electrophoresis. DNA homology was examined by the S1 nuclease method, using [3H]-labeled DNA from H. pylori NCTC11637 and two H. pylori isolates for reference. RESULT: Intergenus DNA homology between H. pylori and Campylobacters was 50-60%. Interspecies homology between H. pylori and H. mustelae or H. felis was around 60%. Intraspecies homology among H. pylori isolates was above 80%, except for a few that exhibited 70-80% homology. These findings indicate that all H. pylori isolates were homogeneous and belonged to the same species. Notl pulse-field gel electrophoresis patterns of H. pylori isolates differed markedly at the individual strain level. There was no specific relationship to any deviation from DNA homology, and the differences were observed within rather homogeneous members of the species. CONCLUSION: The polymorphism in the Notl pulse-field gel electrophoresis patterns of H. pylori isolates differed markedly among strains, even though these isolates displayed species homogeneity, with DNA homology of 70-100%.

Campylobacter↗

PubMed1994

[Hypervascular liver metastases of gastric cancer completely responding to transcatheter oily chemoembolization using epirubicin hydrochloride, mitomycin C and lipiodol].

A 68-year old woman underwent transarterial oily chemoembolization using Lipiodol with epirubicin hydrochloride and mitomycin C for treatment of multiple hypervascular hepatic metastases of gastric cancer. The tumors showed a good fixation of Lipiodol with a complete biologic response. The tumor has been well controlled for eight months by only one chemoembolization on follow-up study. Transcatheter oily chemoembolization may be an effective treatment not only for hepatocellular carcinoma, but also for hypervascular liver metastases from gastrointestinal malignancies.

Adenocarcinoma↗

PubMed1993

Partial brachiocephalic perfusion in aortic arch replacement.

Eleven patients who underwent replacement of the aortic arch or adjacent areas for aneurysmal disease between 1989 and 1991, using hypothermic cardiopulmonary bypass at 20 degrees to 23 degrees C with partial brachiocephalic perfusion, were studied. Selective perfusion of the innominate artery was performed in all 11 patients through the right axillary artery, while partial brachiocephalic perfusion was carried out using a separate arterial roller pump with a perfusion flow rate of 10 ml/kg per min. Direct cannulation to the left common carotid and left subclavian artery was not performed in this method. There were 4 men and 7 women who ranged in age from 26 to 78 years, with a mean age of 56 years. The etiology of aneurysmal disease was aortic dissection in 10 patients, and aortitis syndrome in 1. The cardiopulmonary bypass time was 214.3 +/- 39.3 min, aortic cross-clamp time 131.5 +/- 33.4 min, and partial brachiocephalic perfusion time 57.6 +/- 15.1 min. There were three operative deaths (27.3%), the causes being multiple organ failure, acute peritonitis, and infection of the composite graft in the ascending aorta, in one patient each, respectively. However, there were no deaths related to the technique of partial brachiocephalic perfusion and no neurological complications were seen in this series. Thus, we believe that partial brachiocephalic perfusion under hypothermic cardiopulmonary bypass is safe and effective in surgery for aortic aneurysms involving the aortic arch.

Adult↗

PubMed1993

Detection of bovine coronavirus by enzyme-linked immunosorbent assay using monoclonal antibodies.

A sensitive and highly specific enzyme-linked immunosorbent assay (ELISA) system for detection of bovine coronavirus was developed using monoclonal antibodies, which showed both neutralization and hemagglutination inhibition activities. A monoclonal antibody was coated onto microplates for capturing antigen and a mixture of two monoclonal antibodies served as detecting antibodies. Using this assay, 40 of 202 fecal specimens from 29 herds were shown to be positive for viral antigen. From 10 ELISA positive specimens from 5 herds, the virus was isolated after several passages on human rectal adenocarcinoma (HRT-18) cell culture.

Animals↗

PubMed1993

[Partial brachiocephalic perfusion in aortic arch replacement].

Twenty patients with aneurysm or dissection of the aortic arch underwent surgical treatment using partial brachiocephalic perfusion (PBP). The right subclavian artery (SA) and common femoral artery were separately cannulated and perfused by individual pump heads. The flow to SA was 4.5-11 (9.9 +/- 1.4) ml/min/kg. The mean distal stump pressure of the left superficial temporal arteries before beginning the CPB were 36-64 (50.6 +/- 8.3) mmHg. The rectal temperature during PBP was maintained at 20.1-25.0 degrees C. The PBP time ranged 32 to 157 min. We studied the oxygen saturation of left internal jugular vein (SjO2) and cerebral circulatory index (CCI) during the PBP. SjO2 ranged from 72.9 to 99.4% and CCI were maintained at more than twice the CCI measured before beginning the CPB. We applied this simplified method (PBP) to the 20 patients with aortic aneurysms. No neurological complication were seen in these 19 patients without one patient. These clinical studies suggest that the PBP under hypothermic CPB is a safe and reliable method of cerebral protection for replacement of the aortic arch.

Adult↗

PubMed1993

[Hepatic metastases from jejunal leiomyosarcoma treated effectively by repeated transarterial embolization with carboplatin].

A 67-year-old man complained of abdominal mass, abdominal pain and tarry stool. He was diagnosed as having jejunal leiomyosarcoma and multiple liver metastases after examination. The jejunal leiomyosarcoma was resected by operation. Unrectable liver metastases were repeatedly treated by transarterial embolization with carboplatin and Lipiodol, and a significant reduction was achieved. TAE with carboplatin and Lipiodol was considered evaluating efficiency therapy without side effect. He has remained well presently for 1 years 10 months after operation.

Aged↗

PubMed1992

Partial brachiocephalic perfusion under hypothermic cardiopulmonary bypass. An experimental study.

We studied electrophysiological, oxygen metabolic, and histological variables in dogs to establish the reliability and safety of partial brachiocephalic perfusion (PBP) under hypothermic cardiopulmonary bypass (CPB) at 23 degrees-25 degrees C. Sixteen mongrel dogs were divided into two groups. Six (control group) underwent typical hypothermic CPB for 90 min, and 10 (PBP group) underwent PBP under hypothermic CPB for 90 min. During core cooling on the CPB, a progressive reduction in voltage and slowing of frequency of the electroencephalogram (EEG) was observed. At around 23 degrees C nasopharyngeal temperature the tracing became almost flat and remained so throughout the hypothermic CPB or the PBP under hypothermic CPB. Consistent recovery of the EEG was, however, observed during the period of rewarming on the CPB, and the voltage and frequency of the EEG recovered to control levels on weaning off CPB at 36 degrees C in both groups. In the PBP group, the cerebral arteriovenous oxygen (AVO2) difference was 12.4 +/- 4.0 vol% before beginning the CPB, and it was 5.6 +/- 2.7, 5.7 +/- 3.1, 5.4 +/- 3.3, and 4.9 +/- 2.9 vol% at 10, 30, 60, and 90 min respectively after commencement of the PBP under hypothermic CPB. The cerebral AVO2 difference measured 10 min after commencement of the PBP was significantly less than that in the control group (P less than 0.05), but otherwise there were no significant differences between cerebral AVO2 differences in the two groups. Concentration of serum creatine kinase-BB (CK-BB) gradually increased in proportion to the duration of CPB in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗