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Biomedical subjects

K Nishigaki

Publications and source records attributed to K Nishigaki.

At least 109 records · Page 6Linked to original sources
PubMed1990

[Extended direct anastomosis for coarctation of the aorta and interruption of the aortic arch].

Between March, 1986 and May, 1988, extended direct anastomosis was performed for coarctation of the aorta (CoA) (5 infants) and interruption of the aortic arch (IAA) (3 infants). The aortic arch was hypoplastic in 3 patients. The incision was made in the inferior aspect of the aortic arch proximal to the origin of the carotid or brachiocephalic artery, which was then anastomosed to the descending aorta. Pulmonary artery banding was placed in 4 patients with associated complex cardiac anomalies. Aortic cross-clamp time was 19-54 minutes (mean 41 minutes). Pressure gradient between upper and lower extremity was 0-10 mmHg (mean 4 mmHg). There were no operative deaths and no neurologic complications. The peak flow velocity at the site of aortic reconstruction measured by Doppler echocardiographic study after surgery was 1.2-2.5 m/sec (mean 1.7 m/sec). This procedure has the advantages of leaving the subclavian artery intact and no aortic shelf tissue. And it can be applied in IAA or CoA with hypoplastic aortic arch.

Aorta, Thoracic↗
PubMed1989

[External conduit repair with "valved pericardial roll"].

External conduit repair was performed in 20 patients with "valved pericardial roll (VPR)" made of own pericardium (one case) or porcine pericardium (19 cases). Intraoperative measurement of peak pressure gradients across the valve ranged from 0 to 8 mmHg (mean 1), and that from the pulmonary ventricle to the pulmonary artery ranged from 0 to 38 mmHg (mean 20). Re-evaluation of 7 patients one year after surgery shows no increase in the pressure gradient except the first case, in which VPR was made of own pericardium. In pulsed Doppler echocardiographic study, no regurgitation was found in 4 patients, mild in 6, moderate in 4, severe in 1. VPR is functioning well with longest follow up at 16 months.

Adolescent↗
PubMed1988

Use of a paracorporeal pneumatic ventricular assist device for postoperative cardiogenic shock in two children with complex cardiac lesions.

Pneumatic ventricular assist device (VAD) was utilized for cardiogenic shock after intracardiac operation in two children with complex cardiac anomalies based with single ventricle. In the first case (a 10-year-old), after a modified Fontan operation, VAD was placed between the functional left atrium and ascending aorta, serving as a "artificial single ventricle" with neither pumping chamber nor artificial support in the right side of the heart. The systemic circulation was maintained by keeping relatively high central venous pressure. In another child (a 3-year-old) who underwent repair of incompetent atrioventricular valve leaving intracardiac lesions, VAD was placed between the common atrium and ascending aorta, serving as a pump for both pulmonary and systemic circulation with regulation of pulmonary blood flow through an aortopulmonary Gore-Tex shunt. The circulatory assist with VAD was utilized for 5 and 6 days, respectively. Although weaning from the device was not feasible in both patients because of the pulmonary dysfunction, these experience showed the possible use of VAD for cardiogenic shock after surgery in patients with complex cardiac anomalies.

Assisted Circulation↗
PubMed1988

Bacterial bioassay of microgram to subnanogram quantities of glucose.

A simple and highly sensitive bioassay for the measurement of glucose is described. The method is based on the fact that the yields of cultured bacteria depend on the amount of glucose input, which is a limiting factor in Davis minimal medium. The number of cells cultured under fixed conditions was shown to be dependent on the amount of glucose in the culture medium. Therefore, the concentration of glucose can be measured by counting the cell number after culturing the bacteria. With Davis medium depleted of sodium citrate, we used this method to detect a subnanogram level of glucose, although with the accuracy of order of magnitude estimation. In the microgram per milliliter range of glucose, the cell number can be measured optically, with proliferation being proportional to the input glucose. The high selectivity for glucose of this method is based on the preferential usage of glucose as a carbon and energy source by the bacteria adopted. The feasibility of applying this method to other substances is discussed.

Bacteriological Techniques↗
PubMed1988

Acute liver dysfunction after modified Fontan operation for complex cardiac lesions. Analysis of the contributing factors and its relation to the early prognosis.

Acute liver dysfunction was analyzed in 15 patients who received a modified Fontan operation for single ventricle in nine (atrial isomerism, seven) and tricuspid or mitral atresia in six. Nine patients had elevation of serum glutamic-pyruvic transaminase levels above 1000 U/L during the first week. As an analysis of postoperative liver function during the first week, the highest values of serum glutamic-pyruvic transaminase and total bilirubin and the lowest prothrombin time were scored from 0 to 4 within each parameter, and totaled to give a liver dysfunction score. The liver dysfunction score was 0 to 2 (no or trivial injury) in five patients, 3 to 5 (mild) in two, and 6 to 11 (moderate or severe) in eight (53.3%). The group operated on for single ventricle had a higher incidence (67%) of a liver dysfunction score of 6 or higher than the other group (33%). A multivariate analysis for the prediction of the liver dysfunction score mainly from early postoperative hemodynamics showed the highest correlation with cardiac index, followed by urine output, systolic arterial pressure, and central venous pressure. One patient required plasmapheresis. Four died early (less than 1 month); three of these had a liver dysfunction score of 6 or higher. Those with scores of 6 or above had higher serum glutamic-pyruvic transaminase levels at 1 month after operation than those with scores less than 5. In three patients (single ventricle), hepatic venous oxygen saturation was monitored and showed a marked decrease to below 20% with subsequent acute liver dysfunction. These results indicate that acute liver dysfunction appears to occur in patients with complex lesions after a modified Fontan operation from possible hepatic hypoperfusion and that low cardiac output may be more crucial than high central venous pressure alone.

Acute Disease↗
PubMed1987

Problems in the modified Fontan operation for univentricular heart of the right ventricular type.

Thirteen patients (ages 4 to 16 years) with univentricular heart of right ventricular type, nine with double-inlet right ventricle (DIRV), and four with mitral atresia who underwent a modified Fontan operation were reviewed. Among those with DIRV, right isomerism with a common atrioventricular (AV) valve was found in eight and situs inversus in one; among those with mitral atresia, AV discordance was found in two and concordance in two. Intra-atrial routing using a baffle with atriopulmonary anastomosis was the main procedure (11 patients). There were two operative deaths (one DIRV, one mitral atresia) and three hospital deaths, with an early mortality of 38.5% overall (DIRV 44%, mitral atresia 25%). Low cardiac output was the main cause of death, with relatively high right atrial pressure and with tachyarrhythmias in most of the patients. Mortality was 75% for patients with DIRV who had total anomalous pulmonary venous drainage (n = 4) and 20% for those without (n = 5). Preoperative ventricular volume and ejection fraction were not different between those with severely low cardiac output (n = 4, three deaths) and the others, whereas ventricular mass/volume ratio was significantly lower in the former group. Two late deaths (one DIRV, one mitral atresia) related to the AV valve regurgitation. These results may indicate a relatively poor outcome after the modified Fontan operation for patients with univentricular heart of right ventricular type as a result of basic anatomic and hemodynamic problems.

Arteriovenous Shunt, Surgical↗
PubMed1986

Detection of differences in higher order structure between highly homologous single-stranded DNAs by low-temperature denaturant gradient gel electrophoresis.

Denaturant gradient gel electrophoresis performed at low temperature was shown to be able to detect the mobility change corresponding to the denaturation of the secondary structure of single-stranded(ss)DNA. Mobility transitions observed were determined to correspond to the melting of local structures, since both denaturants and temperature were verified to have similar effects on the mobility transition of single-stranded DNAs as on that of double-stranded DNAs. In this study it was found that point mutations can effectively change the secondary structures of ssDNA and RNA, and that the method adopted here is very sensitive to such alterations. The validity of the method was supported by a computer analysis of the secondary structure of DNA.

DNA, Single-Stranded↗
PubMed1985

Type II restriction endonucleases cleave single-stranded DNAs in general.

Restriction endonucleases (13 out of 18 species used for the test) were certified to cleave single-stranded(ss)DNA. Such enzymes as AvaII, HaeII, DdeI, AluI, Sau3AI, AccII,TthHB8I and HapII were newly reported to cleave ssDNA. A model to account for the cleavage of ssDNA by restriction enzymes was proposed with supportive data. The essential part of the model was that restriction enzymes preferentially cleave transiently formed secondary structures (called canonical structures) in ssDNA composed of two recognition sequences with two fold rotational symmetry. This means that a restriction enzyme can cleave ssDNAs in general so far as the DNAs have the sequences of restriction sites for the enzyme, and that the rate of cleavage depends on the stabilities of canonical structures.

Base Sequence↗
PubMed1984

Strand dissociation and cooperative melting of double-stranded DNAs detected by denaturant gradient gel electrophoresis.

Precise analysis using the denaturant gradient gel electrophoresis which was devised by Fischer and Lerman (Cell 16, 191-200, 1979), was found to present specific patterns of fine structures for double stranded DNA fragments. These seem to be a mobility change of DNA fragments caused by specific denaturation processes. The effect of denaturants on DNA melting was ascertained to be similar to the effect of temperature. The observed patterns, in comparison with the melting processes of DNAs theoretically obtained, were closely related to DNA meltings and strand dissociations. A number of electrophoretic mobility transitions showed the retardation correspondent to each of the cooperative meltings. Strand dissociations occurred under the conditions theoretically predicted. The degree of retardation in electrophoresis for DNA fragments seemed to correspond to the size of melted regions. Methods presented here were proved to have advantages over the conventional ones for the study of DNA stability maps.

Computers↗