Factors considered by medical students when formulating their specialty preferences in Japan: findings from a qualitative study.

BACKGROUND: Little research addresses how medical students develop their choice of specialty training in Japan. The purpose of this research was to elucidate factors considered by Japanese medical students when formulating their specialty choice. METHODS: We conducted qualitative interviews with 25 Japanese medical students regarding factors influencing specialty preference and their views on roles of primary versus specialty care. We qualitatively analyzed the data to identify factors students consider when developing specialty preferences, to understand their views about primary and subspecialty care, and to construct models depicting the pathways to specialization. RESULTS: Students mention factors such as illness in self or close others, respect for family member in the profession, preclinical experiences in the curriculum such as labs and dissection, and aspects of patient care such as the clinical atmosphere, charismatic role models, and doctor-patient communication as influential on their specialty preferences. Participating students could generally distinguish between subspecialty care and primary care, but not primary care and family medicine. Our analysis yields a "Two Career" model depicting how medical graduates can first train for hospital-based specialty practice, and then switch to mixed primary/specialty care outpatient practice years later without any requirement for systematic training in principles of primary care practice. CONCLUSION: Preclinical and clinical experiences as well as role models are reported by Japanese students as influential factors when formulating their specialty preferences. Student understanding of family medicine as a discipline is low in Japan. Students with ultimate aspirations to practice outpatient primary care medicine do not need to commit to systematic primary care training after graduation. The Two Career model of specialization leaves the door open for medical graduates to enter primary care practice at anytime regardless of post-graduate residency training choice.

Targeted delivery of bone marrow mononuclear cells by ultrasound destruction of microbubbles induces both angiogenesis and arteriogenesis response.

OBJECTIVE: Ultrasound (US)-mediated destruction of contrast microbubbles causes capillary rupturing that stimulates arteriogenesis, whereas intramuscular implantation (im) of bone marrow mononuclear cells (BM-MNCs) induces angiogenesis. We therefore studied whether US-targeted microbubble destruction combined with transplantation of BM-MNCs can enhance blood flow restoration by stimulating both angiogenesis and arteriogenesis. METHODS AND RESULTS: US-mediated destruction of phospholipid-coated microbubbles was applied onto ischemic hindlimb muscle and subsequently BM-MNCs were transfused. A significant enhancement in blood flow recovery after Bubble+US+BM-MNC infusion (34% increase, P<0.05) was observed compared with Bubble+US (25%). The ratio of capillary/muscle fiber increased by Bubble+US+BM-MNC-i.v (260%, P<0.01) than that in the Bubble+US group (172%), into which BM-MNCs were incorporated (angiogenesis). Smooth muscle alpha-actin-positive arterioles were also increased, and angiography showed augmented collateral vessel formation (arteriogenesis). Platelet-derived proinflammatory factors activated by Bubble+US induces the expression of adhesion molecules (P-selectin and ICAM-1), leading to the attachment of transplanted BM-MNCs on the endothelium. Flow assay confirmed that the platelet-derived factors cause the adhesion of BM-MNCs onto endothelium under laminar flow. CONCLUSIONS: This study demonstrates that the targeted delivery of BM-MNCs by US destruction of microbubbles enhances regional angiogenesis and arteriogenesis response, in which the release of platelet-derived proinflammatory factors activated by Bubble+US play a key role in the attachment of transplanted BM-MNCs onto the endothelial layer.

Impact of the angiotensin II receptor antagonist, losartan, on myocardial fibrosis in patients with end-stage renal disease: assessment by ultrasonic integrated backscatter and biochemical markers.

Myocardial fibrosis commonly occurs in patients with end-stage renal disease (ESRD) and has proven to be an important predictor for cardiovascular events. In experimental settings, angiotensin II type 1 receptor (AT1-R) antagonists have been shown to have anti-fibrotic effects on the myocardium independent of their antihypertensive effects. In this study, to investigate whether the AT1-R antagonist losartan would have such anti-fibrotic effects in patients, we administered losartan or, for purpose of comparison, the angiotensin-converting enzyme enalapril or Ca2+-antagonist amlodipine to patients with ESRD. Thirty-nine ESRD patients with hypertension were randomly assigned to receive losartan (n=13), enalapril (n=13), or amlodipine (n=13). Ultrasonic integrated backscatter (IBS) and serological markers of collagen type I synthesis and degradation were used to assess the degree of myocardial fibrosis just before and after 6 months of treatment. There were no significant differences in antihypertensive effects among the three agents. In the enalapril- and amlodipine-treated groups, the mean calibrated IBS values increased significantly after 6 months of treatment (enalapril: -31.6 +/- 1.3 to -29.4 +/- 1.2 dB, p=0.011; amlodipine: -30.6 +/- 1.4 to -27.2 +/- 1.2 dB, p=0.012). However, the mean calibrated IBS values in the losartan-treated group did not increase after 6 months of treatment (-31.2 +/- 1.7 to -31.3 +/- 1.4 dB, p=0.88). The ratio of the serum concentration of procollagen type I carboxy-terminal peptide to the serum concentration of collagen type I pyridinoline cross-linked carboxy-terminal telopeptide was significantly reduced in the losartan-treated group (42.6 +/- 4.6 to 34.4 +/- 3.6, p=0.038). The present study indicates that losartan more effectively suppresses myocardial fibrosis in patients with ESRD than does enalapril or amlodipine despite a comparable antihypertensive effect among the three drugs.

Improvement of collateral perfusion and regional function by implantation of peripheral blood mononuclear cells into ischemic hibernating myocardium.

OBJECTIVE: This study was performed to evaluate the angiogenic effect of implantation of peripheral blood mononuclear cells (PB-MNCs) compared with bone marrow mononuclear cells (BM-MNCs) into ischemic hibernating myocardium. METHODS AND RESULTS: A NOGA electromechanical system was used to map the hibernating region and to inject cells. PB-MNCs and BM-MNCs contained similar levels of vascular endothelial growth factor and basic fibroblast growth factor, whereas contents of angiogenic cytokines (interleukin-1beta and tumor necrosis factor-alpha) were larger in PB-MNCs. Numbers of endothelial progenitors were approximately 500-fold higher in BM-MNCs. In BM-MNC-implanted myocardia of pigs, an increase in systolic function (ejection fraction from 33% to 52%) and regional blood flow (2.1-fold) and a reduction of the ischemic area (from 29% to 8%) were observed. PB-MNC implantation reduced the ischemic area (from 31% to 17%), the extent of which was less than that seen with BM-MNCs. In saline-implanted myocardium, the ischemic area expanded (from 28% to 38%), and systolic function deteriorated. Angiography revealed an increase in collateral vessel formation by PB-MNC or BM-MNC implantation. Capillary numbers were increased 2.6- and 1.7-fold by BM-MNC and PB-MNC implantation, respectively. BM-MNCs but not PB-MNCs were incorporated into neocapillaries. CONCLUSIONS: Catheter-based implantation of PB-MNCs can effectively improve collateral perfusion and regional function in hibernating ischemic myocardium by its ability to mainly supply angiogenic factors and cytokines.

Usefulness of strain rate imaging in detecting ischemic myocardium during dobutamine stress.

BACKGROUND: Tissue Doppler imaging-derived systolic myocardial velocity can detect subtle alterations in contractility during dobutamine stress. However, increased cardiac translation and tethering during dobutamine stress may affect measurements. METHODS: To examine the hypothesis that regional ischemic myocardium can be sensitively detected during dobutamine stress using myocardial strain rate, a new indicator of regional myocardial contraction that is independent of cardiac translation and tethering, we studied seven closed-chest pig confirmed chronic ischemic models produced by placing an ameroid constrictor on the left circumflex artery. Left ventricular short-axis tissue Doppler imaging was obtained at baseline and during dobutamine stress (10 and 30 microg/kg/min). Peak systolic myocardial velocity and peak systolic myocardial strain rate in anterior and posterior segments were derived offline at each stage. RESULTS: In peak systolic myocardial velocity and peak systolic myocardial strain rate, repeated-measures analysis of variance showed significant interaction between nonischemic and ischemic segments during dobutamine stress. Statistical significance between nonischemic and ischemic segments was reached at baseline, 10 microg/kg/min dobutamine, and 30 microg/kg/min dobutamine in peak systolic myocardial strain rate, and at 30 microg/kg/min dobutamine in peak systolic myocardial velocity. By receiver operating characteristic (ROC) analysis for predicting ischemic segments at 30 microg/kg/min dobutamine, a cutoff value of peak systolic myocardial strain rate was 4.84, with a sensitivity of 100% and a specificity of 100%. Peak systolic myocardial velocity was the less discriminating parameter (cutoff, 6.46; sensitivity, 86%; specificity, 86%). CONCLUSIONS: Myocardial strain rate imaging might represent an accurate parameter for clinical recognition of regional ischemic myocardium during dobutamine stress echocardiography.

Ultrasound evaluation of valsartan therapy for renal cortical perfusion.

An increase in renal blood flow with a concomitant decrease in filtration fraction at the onset of angiotensin II receptor blocker treatment has been shown to predict a long-term renoprotective effect. However, no studies are available regarding angiotensin receptor blocker-induced changes in renal cortical perfusion observed in the clinical setting. We have recently developed a convenient method of evaluating human renal cortical blood flow with contrast-enhanced harmonic ultrasonography. The goal of this study was to use this method to examine the effect of valsartan, an angiotensin II receptor blocker, on renal cortical perfusion. We performed intermittent second harmonic imaging with venous infusion of a microbubble contrast agent in 7 healthy volunteers. Contrast-enhanced harmonic ultrasonography performed after oral administration of valsartan (80mg) showed a significant increase in microbubble velocity, which correlated well with the increase in total renal blood flow determined by p-aminohippurate clearance (r=0.950, p < 0.001). Although fractional vascular volume was not significantly increased, alterations in renal cortical blood flow calculated by the product of microbubble velocity and fractional volume were also correlated with the change in total renal blood flow (r=0.756, p < 0.05). These results indicate that valsartan increases the renal cortical blood flow in normal kidneys, mainly by increasing blood flow velocity. Contrast-enhanced harmonic ultrasonography is a promising technique for evaluating the precise effect on renal cortical perfusion and optimal dose of valsartan in diseased kidneys.

[Angiotensin II type 1 antagonist suppress left ventricular hypertrophy and myocardial fibrosis in patient with end stage renal disease (ESRD)].

Fibrosis of left ventricle commonly occurs in end stage renal disease(ESRD) patients and is an independent risk factor of cardiovascular events. Angiotensin II type 1 receptor antagonist may be able to reverse fibrosis of left ventricle in ESRD patients. Ultrasonography-integrated backscatter(IBS) of myocardial walls is directly related to the morphometrically evaluated collagen content in humans. In this study, 30 chronically hemodialyzed patients with hypertension were randomly allocated to receive antihypertensive therapy with either angiotensin II type 1 receptor(AT1-R) antagonist losartan(n = 10), angiotensin-converting enzyme(ACE) inhibitor enalapril(n = 10) or calcium antagonist amlodipine(n = 10). IBS of posterior wall of left ventricule were measured by IBS before and after 6 months treatment. Baseline demographic and clinical characteristics did not differ in three subgroups. Although losartan(34.2 +/- 1.8 to 30.2 +/- 2.4 dB: p = 0.0094) treatment demonstrated significant reduce of IBS values, enalapril(30.3 +/- 1.5 to 31.7 +/- 1.4 dB: p = 0.3268) and amlodipine (31.6 +/- 1.6 to 33.1 +/- 1.9 dB: p = 0.4632) did not changed it significantly before and after 6 months treatment. All three groups reduced left ventricular mass index(Losartan 154.5 +/- 9.9 to 114.6 +/- 5.8 g/m2: p = 0.0002) (enalapril 155.6 +/- 14.3 to 135.3 +/- 10.4 g/m2: p = 0.0275) (amlodipine 156.6 +/- 7.3 to 137.2 +/- 4.1 g/m2: p = 0.0589). Three groups manifested a similar significant decrease in the mean blood pressure. Plasma angiotensin II concentration was markedly increased by 5.0-fold relative to the control levels before treatment in Losartan treatment, in contrast unchanged in enalapril and only 2.0-fold increased in amlodipine treatment. This study indicates that losartan reduce of fibrosis of left ventricule and this effect may be via an anti-AT1-R effect.

Hepatocyte growth factor delivered by ultrasound-mediated destruction of microbubbles induces proliferation of cardiomyocytes and amelioration of left ventricular contractile function in Doxorubicin-induced cardiomyopathy.

At present, there is no curative strategy for advanced cardiomyopathy except for cardiac transplantation, which is not easily performed, mainly due to a shortage of donors. It has been reported that myocardial progenitor cells exist even in the postnatal heart, suggesting that myocardial progenitor cells could proliferate under some situations and might improve cardiac function in cardiomyopathy-induced hearts. In this study, recombinant human hepatocyte growth factor (rhHGF) was delivered using ultrasound-mediated destruction of microbubbles (UMDM) into the cardiomyopathy-induced heart by doxorubicin (20 mg/kg). Intravenous injection of rhHGF (IV-rhHGF) alone or UMDM alone failed to improve the morphology or the function of the cardiomyopathy-induced heart, but (IV-rhHGF + UMDM) treatment significantly improved the heart morphologically and functionally, and repetitive treatments of (IV-rhHGF + UMDM) enhanced the effects. The number of bromodeoxy-uridine-positive cardiomyocytes significantly increased in the (IV-rhHGF + UMDM)-treated hearts compared with the untreated hearts. Moreover, Sca-1+ myocardial progenitor cells express c-Met, a receptor for HGF. These results suggest that (IV-rhHGF + UMDM) treatment could morphologically and functionally improve the heart in the case of doxorubicin-induced cardiomyopathy through the proliferation of the myocardial progenitor cells.

[Uremic pericarditis complicating cardiac tamponade: a case report].

A 29-year-old man developed diabetes mellitus in 1983 and diabetic nephropathy which gradually worsened from 1998. He was admitted to our hospital for initiation of peritoneal dialysis in May 2002. However, the efficiency of dialysis was not sufficient to improve elevated levels of blood urea nitrogen and serum creatinine. His body weight and cardiothoracic index by chest roentgenography gradually increased starting 9 days after admission. To improve the efficiency of dialysis, we tried to increase the dialysis fluid. Nevertheless, the efficiency of peritoneal dialysis remained low, and the patient complained of nausea 14 days after admission. Hypotension suddenly occurred 16 days after admission. Echocardiography showed massive pericardial effusion and collapse of the right ventricle. The diagnosis was cardiac tamponade. We performed cardiac centesis and pericardial drainage which revealed bloody pericardial effusion. Urgent hemodialysis was performed. The differential diagnosis of cardiac tamponade was established. After hemodialysis, the amount of pericardial effusion decreased, the gastro-intestinal symptoms disappeared, and the blood urea nitrogen and serum creatinine levels decreased. We speculated that the cause of cardiac tamponade was uremic pericarditis after ruling out infectious disease, collagen disease, malignant disease, and aortic dissection. Cardiac tamponade due to uremic pericarditis has become very rare since hemodialysis was developed.

Angiotensin II type 1 receptor antagonist, losartan, causes regression of left ventricular hypertrophy in end-stage renal disease.

Left ventricular hypertrophy (LVH) commonly occurs in patients with end-stage renal disease (ESRD) and is an independent risk factor for cardiovascular events. Angiotensin II type 1 receptor (AT1-R) antagonists may be able to reverse LVH independent to the hypotensive effect in the ESRD setting. Thirty chronically hemodialyzed uremic patients with hypertension were randomly assigned to receive the AT1-R antagonist losartan (n = 10), the angiotensin-converting enzyme (ACD) inhibitor enalapril (n = 10), or calcium antagonist amlodipine (n = 10). Left ventricular mass (LVM) index was measured by echocardiography before and 6 months after treatment. The baseline demographic and clinical characteristics did not differ between the three groups. The mean baseline LVM index also did not differ in the three groups. After 6 months of treatment, losartan treatment significantly reduced the LVM index (-24.7 +/- 3.2%) than amlodipine (-10.5 +/- 5.2%) or enalapril (-11.2 +/- 4.1%) therapy. All three groups had a similar decrease in the mean blood pressure with treatment. The plasma angiotensin II concentration increased 5-fold with losartan treatment. In contrast, the plasma angiotension II concentration did not change with enalapril and only increased 2-fold with amlodipine. Thus, the present study indicates that losartan more effectively regresses LVH in patients with ESRD than do enalapril and amlodipine despite a comparable depressor effect between the three drugs.

[Infective endocarditis complicating bilateral bacterial ophthalmitis: a case report].

A 53-year-old female suddenly went blind in her left eye on 3 June, 2000. She was admitted to the Department of Ophthalmology of our hospital under the diagnosis of endophthalmitis. Her left eye was enucleated, and Streptococcus agalactiae was found in the vitreous fluid. After left ophthalmectomy, inflammation recurred after cessation of antibiotic administration. Echocardiography demonstrated a vegetation of the posterior mitral valve. The diagnosis was infective endocarditis. She was transferred to the Department of Internal Medicine. Mitral regurgitation deteriorated during the course of medical therapy, but she was discharged on 13 September, 2000 because inflammation had improved remarkably and the vegetation had disappeared after administration of penicillin G, panipenem, cefotaxime and clindamycin. We suspected that embolism of the ophthalmic artery was the cause of the sudden blindness in her left eye. Infective endocarditis with bacterial endophthalmitis is very rare in Japan.