Trend in unequal geographical distribution of dentists by age and gender in Japan from 1996-2014.

OBJECTIVES: To evaluate the relationship between dentists' demographic changes and their uneven geographical distribution. METHODS: Secondary analysis of nationwide government surveys, to assess trends in the geographical distribution of dentists by gender and age from 1996 to 2014 in Japan. RESULTS: The Gini-coefficient for the number of dentists per population from 47 prefectures decreased from 0.084 in 1996 to 0.069 in 2014. The coefficients for female (0.124-0.144) were higher than for male dentists (0.058-0.081). Coefficients for dentists aged 60 and older were lower than those for dentists younger than 40 in 2014 (male: 0.060 vs. 0.112; female: 0.107 vs. 0.169). CONCLUSION: The geographical maldistribution of dentists in Japan has improved. Demographic changes among dentists, including the increasing number of female dentists, could moderate this improvement.

Ultralow-repetition-rate, high-energy, polarization-maintaining, Er-doped, ultrashort-pulse fiber laser using single-wall-carbon-nanotube saturable absorber.

An ultralow-repetition-rate, all-polarization-maintaining (PM), Er-doped, ultrashort-pulse fiber laser was demonstrated using a single-wall-carbon-nanotube polyimide film. Using a ring cavity configuration, output pulses with pulse energy of 0.7-2.6 nJ were obtained at an ultralow repetition rate of 943-154 kHz for a fiber length of 0.1-1.3 km. A novel θ (theta) cavity configuration was proposed, which enabled us to reduce the required fiber length by half. A repetition rate of 132 kHz was achieved using this configuration with 909 m of PM fiber.

Polarization-maintaining, high-energy, wavelength-tunable, Er-doped ultrashort pulse fiber laser using carbon-nanotube polyimide film.

A high-energy, wavelength-tunable, all-polarization-maintaining Er-doped ultrashort fiber laser was demonstrated using a polyimide film dispersed with single-wall carbon nanotubes. A variable output coupler and wavelength filter were used in the cavity configuration, and high-power operation was demonstrated. The maximum average power was 12.6 mW and pulse energy was 585 pJ for stable single-pulse operation with an output coupling ratio as high as 98.3%. Wide wavelength-tunable operation at 1532-1562 nm was also demonstrated by controlling the wavelength filter. The RF amplitude noise characteristics were examined in terms of their dependence on output coupling ratio and oscillation wavelength.

Total correction of Ebstein's anomaly by replacement with a biological aortic valve without plication of the atrialized ventricle.

For the surgical management of Ebstein's anomaly, the preferred operation will be Hardy's procedure, which preserves the patient's valve. However, we have encountered 3 cases of this disease in which the downward displacement of the tricuspid valve was so severe and the functioning right ventricle was so small that Hardy's method could not be adapted without causing tricuspid regurgitation and making the right ventricular chamber more narrow. We treated these patients by replacing the tricuspid valve with an inverted aortic valve with a stent and not plicating the atrialized ventricle. The results have been proved satisfactory through about 7 years' follow-up, suggesting that our technique will be remarkably effective as a radical corrective operation for Ebstein's anomaly with severe intracardiac abnormalities.

Oxygenated perfluorocarbon, recombinant human superoxide dismutase, and catalase ameliorate free radical induced myocardial injury during heart preservation and transplantation.

The effect of free radical scavengers on free radical-induced myocardial injury during heart preservation and transplantation was examined. Four groups of nine hearts each were harvested from mongrel dogs (12.5 to 16.5 kg) and orthotopically transplanted to size-matched recipients. All hearts received a continuous perfusion of oxygenated modified Collins' solution (group A). In addition, groups B, C, and D received Fluosol DA and albumin. Preservation perfusion was performed for 18 hours, at 4 degrees C, pH = 7.4, and 20 mm Hg. In group C, recombinant human superoxide dismutase (4,080 U/mg, 20 mg/kg) and bovine catalase (46,200 U/mg, 20 mg/kg) were administered only during preservation perfusion. In group D, these scavengers were administered just before and during reperfusion for 1 hour. Hemodynamic studies were performed before excision of the donor hearts and 1 hour after the termination of cardiopulmonary bypass. Creatinine kinase MB isoenzyme and thiobarbituric acid reactive substance levels in the coronary effluent were determined during preservation perfusion and reperfusion. Only group A showed a significant heart weight gain (p less than 0.05) and a decline in passive compliance (p less than 0.05) during preservation. Lactate release was higher in group A than in the groups receiving Fluosol DA. In contrast, pyruvate levels in group A were lower than in other groups. The generation of free radicals stayed at a low level during preservation, but significantly increased during reperfusion and was associated with a corresponding increase in creatinine kinase MB isoenzyme. Perfusion with a perfluorochemical solution (group B) inhibited the sharp rise in levels of thiobarbituric acid reactive substances and of creatinine kinase MB isoenzyme and improved cardiac function during reperfusion (versus group A). Exogeneous free radical scavengers administered just before and during reperfusion (group D) significantly ameliorated thiobarbituric acid reactive substances and creatinine kinase MB isoenzyme levels and also induced a significant hemodynamic improvement during reperfusion. However, administration of scavengers during preservation did not. This study demonstrates that the generation of free radicals is primarily significant during reperfusion and reoxygenation after ischemia. Thus the best time for administration of scavengers is just before and just after the onset of reperfusion. Furthermore, perfusion with perfluorochemicals effectively maintains aerobic metabolism and ameliorates free radical damage during this period.

Successful extended hypothermic cardiopulmonary preservation for heart-lung transplantation.

The inability to obtain sufficiently extended hypothermic organ preservation is a major restriction on clinical heart-lung transplantation. We used core cooling, nonrecirculating retrograde heart perfusion, and lung immersion with liposomal recombinant human superoxide dismutase in an attempt to provide effective 12-hour cardiopulmonary preservation. Donor dogs supported by cardiopulmonary bypass were rapidly cooled to 15 degrees C with cardioplegic arrest, and heterotopic heart and unilateral left lung transplantations were performed. In control dogs (n = 7), hearts and lungs, harvested after core cooling and cardioplegic arrest, were transplanted with a total mean ischemic time of 88 +/- 5 minutes. In group II (n = 7), heart-lung blocks were similarly excised but preserved at 4 degrees C for 12 hours (756 +/- 30 minutes) and then transplanted. During preservation, the lungs were immersed in hyperosmolar extracellular solution. For the heart, retrograde coronary sinus perfusion was performed with intracellular solution containing perfluorochemicals at a temperature of 4 degrees C and a rate of 30 ml/hr for 12 hours. In group III (n = 7), donor organs were similarly excised and preserved for 12 hours (726 +/- 39 minutes), except that liposomal recombinant human superoxide dismutase was administered during harvest, preservation, and reperfusion. Myocardial function, assessed by the ratio of end-systolic pressure to end-systolic dimension, after the 12-hour preservation period in both experimental groups was similar to that of the control group 4 and 6 hours after transplantation. The mean arterial oxygen capacity of the transplanted left lung during ventilation with an inspired oxygen concentration of 40% was also similar in each group. In contrast, the 12-hour preservation of pulmonary function assessed by pulmonary vascular resistance, the accumulation of extravascular lung water, and histologic evidence of alveolar wall injury, interstitial edema, and perivascular hemorrhage were significantly impaired in the absence of liposal recombinant human superoxide dismutase. These findings suggest that successful extended cardiopulmonary preservation for heart-lung transplantation is possible with core cooling, nonrecirculating retrograde heart perfusion, and hypothermic lung immersion incorporating liposomal recombinant human superoxide dismutase.

Efficacy of intra-aortic balloon pumping for failing Fontan circulation.

The Fontan circulation occasionally cannot be sustained by currently available medical treatment. In these circumstances, mechanical assistance to the Fontan circulation should be considered. We have experienced three cases where Fontan circulation was assisted by intra-aortic balloon pumping (IABP). The hemodynamic improvement and weaning from IABP were successfully achieved in all cases. One patient survived the serious postoperative course with the aid of IAPB, and two patients died following multiorgan failure, though the circulation had eventually been re-established. By studying the postoperative hemodynamics assisted by IABP, it is concluded that IABP is a reasonable, efficacious strategy to support and to re-establish the failing Fontan circulation, though the changes in hemodynamic variables will not immediately coincide with IABP application.

Serial evaluation of cardiac function with aortic regurgitation caused by serious aortic lesions. A preliminary comparative study with isolated chronic aortic incompetence.

Clinical and hemodynamic appearances of aortic regurgitation caused by serious aortic lesions (AR-Ao-group) seemed more deteriorated than those with isolated chronic aortic regurgitation (AR-group). Often postoperative course and operative outcome are smooth and satisfactory in the AR-Ao-group. To support this observation, serial changes of left ventricular (LV) function and LV sphericity were evaluated before and after operation in ten cases in the AR-Ao-group and compared with those in the AR-group. Before operation, there were no significant differences in LV function between the two groups. Postoperative improvement of LV sphericity and LV function were statistically better in the AR-Ao-group. The LV function reserve was considered sufficiently retained in the AR-Ao-group. Results with this study supported that clinical observation. Therefore, the total correction, at the same time of aortic incompetence and aortic lesions is recommended.

Pulmonary artery connection in the Fontan procedure. Flexible polytetrafluoroethylene conduit for expansion.

From clinical experiences with the Fontan operation in six cases, a few practical contrivances and operative steps are described. We stress that meticulous care should be taken not to cause any stenotic complication in the outflow tract toward the pulmonary artery, particularly by traction of the right atrial appendage only to achieve a direct anastomosis. Conduit repair would be necessitated by cases in order to expand the indicative criteria vertically as well as horizontally. For conduit material, we used consecutively nonvalved polytetrafluoroethylene that was reinforced by handmade stainless steel wire ring (Gore-Tex, Inc) or by spirally built-in stent (IMPRA, Inc). The latter was eventually useful in obtaining natural curving of the conduit without kinking or compression. Some contrivances in anastomosing a conduit were also proposed to achieve an excellent result. We believe these practical contrivances will serve for expansion of the indicative criteria and promise improved operative outcome.

The impact of FK506 on graft coronary disease of rat cardiac allograft--a comparison with cyclosporine.

We studied the impact of FK506, a potent immunosuppressant, on graft coronary disease and graft-infiltrating lymphocyte subset after rat heart transplantation. Fisher rat heart grafts transplanted into Lewis rat recipients were divided into three groups: control (n = 7), rats treated with FK506 at a dose of 0.32 mg/kg/day intramuscularly (n = 7), and rats treated with cyclosporine at a dose of 10 mg/kg/day intramuscularly (n = 7). Grafts were removed on day 71 in the treated groups and on rejection in the control group. We blindly scored graft rejection and graft coronary disease on a scale of 0 to 4. Graft-infiltrating lymphocytes were investigated by flow-cytometric analysis with the following monoclonal antibodies: W3/25, anti-helper T lymphocyte; OX8, antisuppressor and cytotoxic T lymphocyte; and OX39, antiinterleukin-2 receptor. No difference of graft rejection was found between the two treated groups (FK506 1.66 +/- 0.49 versus cyclosporine 1.45 +/- 0.37), but the FK506 group showed severe graft coronary disease (FK506 2.14 +/- 0.82 versus cyclosporine 0.78 +/- 0.17; p less than 0.01) in this model. In flow-cytometric analysis, we found an increased proportion of OX8-positive lymphocytes (FK506 25.7 +/- 6.4 versus cyclosporine 4.9 +/- 2.4, p less than 0.01). These results suggest that suppression of cytotoxic T lymphocytes may be involved in graft coronary disease.

Core-cooling, heart-perfusion, lung-immersion technique provides successful cardiopulmonary preservation for heart-lung transplantation.

Mongrel dogs underwent heterotopic heart-orthotopic left lung transplantation. In Group I (N = 6), donor organs procured following core cooling to 15 degrees C on cardiopulmonary bypass (CPB) with cardioplegic arrest were immediately transplanted. In Group II (N = 6), following cardioplegic arrest without CPB core-cooling, the pulmonary artery was flushed with modified Collins' solution. Heart-lung blocks were immersed in extracellular solution for 6 hours and then transplanted. In Groups III and IV (N = 6 each), following CPB core-cooling to 15 degrees C and cardioplegic arrest, the organ blocks were immersed in extracellular solution (Group III) and the heart was perfused with oxygenated extracellular solution (Group IV). Evaluation of lung function using differences in arterial oxygen tension between the left and right atria demonstrated no differences between groups. However, extravascular lung water and pulmonary vascular resistance were significantly elevated in Group II. Cardiac function assessed by the ratio of end-systolic pressure to end-systolic dimension was significantly better in Group IV than in Groups II and III. Thus, adequate 6-hour hypothermic cardiopulmonary preservation with core cooling plus heart perfusion can be achieved for heart-lung transplantation.

alpha-Fluoromethylhistidine decreases the histamine content of the rat right atrium under the influence of sympathetic activity.

alpha-Fluoromethylhistidine (alpha-FMH; 65 mg/kg, i.p.), a specific inhibitor of histidine decarboxylase, significantly decreased the histamine content of the rat right atrium in a time-dependent manner; the maximal decrease of 22.2% was observed 4 h after injection. However, alpha-FMH had no significant effect on the histamine content of the left atrium or the ventricles. The alpha-FMH-induced decrease in the right atrial histamine content was not observed in rats pretreated with 6-hydroxydopamine (25 mg/kg, i.p.). Two i.p. injections of 10 and 5 mg/kg of propranolol and the cardioselective beta 1-adrenoceptor antagonist metoprolol almost completely inhibited the alpha-FMH-induced histamine decrease. On the other hand, phentolamine (10 mg/kg, i.p.) had no influence on the histamine-decreasing action of alpha-FMH. These results suggest that in the rat right atrium there is a histamine pool where a rapid turnover of histamine is maintained by normal sympathetic activity.

Expanded selection criterion for Fontan's operation based on the size of distal pulmonary arteries.

This study examined pulmonary arterial size to clarify a quantitative selection criterion for Fontan's operation in six cases without pulmonary hypertension. Pulmonary arterial size was angiographically assessed before and after the operation. No enlargement of the artery was observed, even after the procedure, confirming the importance of preoperative pulmonary arterial size. All three cases with preoperative PAa/N-RPAa of more than 0.5 survived the operation, whereas two of the remaining three cases (less than 0.5) died due to low cardiac output. The only survivor in the latter group had previously received Glenn's anastomosis. Hemodynamic study was done simultaneously, and a significant exponential correlation was obtained between preoperative PAa/N-RPAa and perioperative post-repair right atrial pressure (p less than 0.025). It was concluded that the selection criterion based on pulmonary arterial size could be expanded to a PAa/N-RPAa value of 0.5 when no Glenn's anastomosis had previously been done and the rudimentary right ventricle was not to be utilized. The exponential curve is useful for postoperative care in Fontan's operation, since it indicates the central venous pressure necessary to sustain the circulation at a level corresponding to the preoperative pulmonary arterial size.

Assessment of left ventricular diastolic function in chronic mitral regurgitation by Doppler left ventricular inflow and left ventricular ultrastructural morphometry.

Doppler left ventricular (LV) inflow is reportedly affected by LV diastolic properties. We evaluated 48 subjects consisting of 27 patients with chronic mitral regurgitation (MR) and 21 patients with noncardiac disorders who received echocardiographic examinations. The deceleration rate divided by diastolic dimension (DR/Dd) derived from Doppler early diastolic LV inflow was correlated with the peak diastolic velocity divided by diastolic dimension (peak DV/Dd), a conventional index of LV diastolic function derived from the M-mode echocardiogram in the 48 patients, regardless of the presence of normal sinus rhythm or atrial fibrillation. LV diastolic function was then estimated by comparing perioperative echocardiographic examination and LV micro-and ultrastructural findings of biopsy specimens from 12 patients with MR who received mitral valve replacement. Fiber diameter, volume fraction of interstitial fibrosis (int. % Fib), and volume fractions of three intracellular components; the myofibrils (% MF), the sarcoplasmic reticulum (% SR) and the mitochondria (% MT), were measured in LV transmural biopsy specimens. DR/Dd was significantly correlated with peak DV/Dd before and after operation. Peak DV/Dd and DR/Dd were inversely correlated with int. % Fib and % SR, and were positively correlated with % MF. We subdivided the 12 MR patients according to their postoperative DR/Dd values as "recovered", and "non-recovered" based on their postoperative LV diastolic function. % MF was significantly lower in the 'non-recovered' group. Thus, DR/Dd can serve as an index of LV diastolic function. A decrease in % MF may inhibit the recovery of postoperative LV diastolic function.

Results of surgery for aortic regurgitation due to aortic valve prolapse.

The clinical, hemodynamic and pathological findings of 13 patients with aortic regurgitation due to aortic valve prolapse caused by advanced myxomatous degeneration were evaluated. Eleven patients showed a favorable outcome with no complications resulting from surgery. One patient died from aortic dissection, and another died suddenly from an unknown cause. Five patients had mitral valve prolapse as a complication. Ten patients (77%) had a long-standing history of hypertension. Twelve patients (92%) were male. None of the patients had the stigmata of Marfan's syndrome. All patients had marked myxomatous degeneration of the aortic valves without any inflammatory changes. Two patients showed microcalcification; 7 demonstrated moderate fibrosis. Five patients showed severe fragility of the cusps which appeared redundant, gelatinous and softened by degenerative changes. Myxomatous degeneration of the aortic valve is not rare, and, in fact, it may be one of the most common pathologic and clinical entities associated with pure aortic insufficiency.

Return to work after heart valve replacement.

One hundred patients who underwent heart valve replacement during the years 1977 to 1985 were reviewed an average of 57 months after surgery. The overall rate of reemployment after the operation was 78%. The most important factors influencing the return to work were the employment status before surgery, age at the time of surgery, the number and site of the diseased valve, the preoperative New York Heart Association (NYHA) functional class and the number of times cardiac surgery was performed. These factors were closely related to the optimal timing of heart valve replacement. It was suggested that the rate of return to work and the quality of life would be improved if the heart valve replacement had been performed at an earlier stage of the disease.

Long-term results of surgery for mitral regurgitation due to mitral valve prolapse: a comparison of valve replacement and annuloplasty.

Patients with mitral regurgitation (MR) due to mitral valve prolapse operated at the Second Department of Surgery, Okayama University Medical School, between 1976 and 1986 were divided into two groups. The first consisted of 20 patients who had mitral valve replacement (MVR) and the second 15 patients who had mitral annuloplasty (MAP). Long-term results of surgery, cardiac function, hemodynamic status, and surgical findings were compared between the two groups. Before surgery, there were no significant differences in patient's clinical status and cardiac function between the two groups. However, after surgery statistically significant differences emerged between the two groups in ejection fraction (EF), cardiac index (CI) and mean circumferential fiber shortening velocity (mVcf). Left ventricular pumping function and myocardial contractile force tended to decrease after surgery in the MVR group and to remain unchanged or even increase in the MAP group indicating that valve preservation procedures should be selected as often as possible for the patients involved in mitral valve prolapse.