Biomedical subjects

Hisao Nakajima

Publications and source records attributed to Hisao Nakajima.

15 recordsLinked to original sources

PubMed2006

Recurrence pattern for superficial bladder cancer.

AIM: Patients with superficial bladder tumors sometimes have long recurrence-free intervals. We evaluated whether patients with long recurrence-free periods had subsequent recurrences. We also clarified how these patients should be followed. MATERIALS AND METHODS: We enrolled 244 patients with superficial bladder cancer (62 pTa and 182 pT1) treated by transurethral resection of bladder tumor (TURBT) and adjuvant chemotherapy with pirarubicin. Median follow up was 75.5 months. Patients were stratified by the length of their recurrence-free interval. RESULTS: Recurrences occurred in 124 patients (50.8%). Of 185 patients who did not have a recurrence for the first 3 years, subsequent recurrences occurred in 65 patients; in more than half the first recurrence developed after 5 years or more. Ta tumors had a low recurrence rate (14.5%) with the first recurrence often developing after a long recurrence-free period. Of 40 patients who remained recurrence-free for 3 years or more after at least one recurrence occurred, 16 patients (40%) had subsequent recurrences. Furthermore, most of these patients who remained free of recurrence for more than 5 years eventually had a recurrence. The overall progression rate was 15.6%, and this did not relate to the length of the recurrence-free interval. CONCLUSION: When patients did not have a recurrence for the first 3 years, tumors subsequently often recurred, even in pTa tumors. In patients with at least once recurrence, subsequent recurrences appear to occur irrespective of the length of the recurrence-free period. Thus, we recommend that all patients with superficial bladder tumors be followed for as long as possible.

Adult↗

PubMed2005

Catastrophic shifts in vertical distributions of phytoplankton: the existence of a bifurcation set.

A model of phytoplankton dynamics within a water column was analyzed with special consideration on the existence of a bifurcation set in the parameter space. We considered two resources, light and a limiting nutrient, for phytoplankton growth and assumed that the water column is separated into two layers by thermal and/or density stratification. It was shown that there exists a bifurcation set in the parameter space when the growth function meets several conditions that are general for growth functions of two essential resources. Specifically, these conditions include that a less abundant of the two resources limits the growth while the effect of the other is sufficiently small. Folded structure with two stable states separated by one unstable state appears in the catastrophe manifold when parameters move to a certain direction with a certain curvature from a point in the bifurcation set. These results suggest that occurrence of discontinuous transition between two alternative vertical patterns is possible nature of phytoplankton dynamics within a stratified water column.

Algorithms↗

PubMed2005

100-minute retroperitoneoscopic radical nephrectomy: a new retroperitoneal approach with a hand assisted method.

PURPOSE: A new approach for retroperitoneoscopic radical nephrectomy is introduced. The point of our surgical method is the application of a combination of hand assistance and pure laparoscopic procedures with appropriate surgical steps via the retroperitoneal approach. In our early series we had good surgical results and we completed radical nephrectomy in about 100 minutes using this procedure. MATERIALS AND METHODS: A total of 20 consecutive patients with renal cell carcinoma (cT1-2) who were operated on with this surgical method were analyzed. Surgical procedures occurred in 5 steps. In step 1 the retroperitoneal space was created manually from a pararectal incision at the umbilicus level. In step 2 the lateroconal fascia was incised and the renal hilar area was exposed with hand assistance. In step 3 hilar dissection was performed by pure laparoscopic procedure with another surgical instrument inserted from the hand device. Step 4 involved the application of hand assistance again for the quick mobilization of the kidney and adrenal gland. In step 5 the intact surgical specimen was retrieved from the hand device. RESULTS: Mean operative time and estimated blood loss were 103 +/- 21 minutes (range 70 to 145) and 49 +/- 85 ml (range 5 to 360), respectively. Mean days to oral intake and ambulation were 1.0 and 1.1, respectively. Operative times of the steps of hilar dissection and mobilization of the kidney and adrenal were shorter than in other series performed by standard retroperitoneoscopic radical nephrectomy. Major complications were not experienced. At this point, no metastasis has been experienced. CONCLUSIONS: Our surgical method may have the benefits of the retroperitoneal approach and hand assistance. The retroperitoneoscopic hand assisted method may be another important option in the 3 major approaches for laparoscopic radical nephrectomy, although longer-term followup is clearly required.

Adult↗

PubMed2005

[Malacoplakia in the ureter and bladder].

We report a case of malacoplakia in the ureter and bladder. A 78-year-old woman was admitted to our department for detailed examination of hydronephrosis. A small-fingertip-sized tumorous yellowish white lesion was detected by cytoscopy at a site that appeared to be the right side of the ureteral orifice. Transurethral resection was performed on the same site. Flat yellowish white protruding lesions were seen at two sites on the right ureter. Michaelis-Gutmann bodies were observed in biopsy specimens from both the bladder and ureter, and a diagnosis of malacoplakia was made. Ascorbic acid and bethanechol chloride were administered postoperatively. Endoscopy performed three months after the operation showed that the protruding lesions in the bladder and ureter had disappeared. Narrowing of the ureter or vesicoureteral reflux has not been seen to date.

Aged↗

PubMed2004

Dietary fiber suppresses elevation of uric acid and urea nitrogen concentrations in serum of rats with renal dysfunction induced by dietary adenine.

This study was conducted to examine the effects of several kinds of dietary fiber (DF) with different physical properties on the elevation of uric acid and urea nitrogen concentrations in serum of rats induced by dietary adenine. DF decreased an uptake of 14C-labeled adenine in the rat jejunum in vitro, but the reduction varied with the physical property of DF. Male Wistar rats (3 weeks old) were fed a diet with or without a 0.4% adenine and a 5% DF (cellulose, chitin, chitosan, or xanthan gum) for 20 days. Feeding of adenine in the fiber-free group elevated the concentrations of uric acid, creatinine, and urea nitrogen in serum, but decreased the excretions of these compounds into urine and increased the amounts of 2,8-dihydroxyadenine (2,8-DHA) in kidney and urine. The test DF was found to suppress the elevation of uric acid, creatinine, and urea nitrogen concentrations in serum induced by dietary adenine, and to mitigate the decreased excretions of these compounds into urine and the increased retention of 2,8-DHA in kidney and urine. This phenomenon was remarkable in the xanthan gum group. These results suggest that DF suppresses the elevation of uric acid and urea nitrogen concentrations in serum by attenuating the absorption of dietary adenine.

Adenine↗

PubMed2004

Characteristics of patients with staghorn calculi in our experience.

PURPOSE: To elucidate the factors contributing to staghorn stone formation in patients. MATERIALS AND METHODS: The records of 82 patients (44 men and 38 women) with complete staghorn calculi were reviewed retrospectively for clinical presentation, metabolic disturbances and anatomical abnormalities. RESULTS: There were 79 unilateral and three bilateral cases. The patient performance of the activities of daily life was assessed with the modified Rankin scale (MRS) and it was found that 69 patients were functionally independent (84.1%, MRS 0-1) and 10 patients had a severe disability (12.2%, MRS 4-5). Seven patients had chronic indwelling catheters (8.5%). A positive urine culture was found in 24.4% of patients. Analysis of stone composition revealed magnesium ammonium phosphate and mixed calcium oxalate-phosphate were the most frequently identified types of stone (32.1% and 22.2%, respectively). Urinary pH was low in patients with uric acid stones (mean 5.4). Hyperuricemia, cystinuria and hypercalciuria were found in 14.6%, 2.4% and 37.8%, respectively. Hypercalciuria was found more frequently in calcium-stone cases. Eleven patients (13.4%) showed structural abnormalities of the kidney. CONCLUSIONS: Our data show that the patients with severe disability, urinary tract infection and hypercalciuria could be recognized more frequently in staghorn calculi compared with common urolithiasis. However, in Western countries, the frequency of both urinary tract infection and struvite stones is much higher than in our data. Other Japanese authors have also reported the low frequency of struvite stones in staghorn calculi, suggesting that various factors other than urinary tract infection possibly contribute to the formation of staghorn calculi in Japan.

Activities of Daily Living↗

PubMed2004

[Analysis of clinical manifestations and endocrinological aspects of patients having PADAM-like symptoms].

PURPOSE: To analyze clinical manifestations and endocrinological aspects of the patients who visited our hospital to be examined for partial androgen deficiency in the aging male (PADAM). MATERIALS AND METHODS: Two hundred forty-three patients were evaluated. History taking and questionnaires were employed for analysis of their symptoms. Serum total testosterone (T), free-T and other hormones were measured for evaluation of the androgen deficiency. RESULTS: The chief complains of the patients were categorized as psychological symptoms, somatovegatative symptoms, and sexual symptoms, accounting for 51%, 36%, and 13%, respectively. A depressed mood, hot flashes and sweating and erectile dysfunction were dominant in these symptom categories, respectively. The prevalence of the psychological symptoms and somatovegatative symptoms was relatively high in the 30-50-year-old and 60-70-year-old groups, respectively. The free-T, but not total-T, was significantly decreased with aging as measured by the RIA method. Twenty one percent of the patients showed a lower total-T level than the normal range (2.7-10.7 ng/ml). The percentage of those with a total-T level lower than 2.0 ng/dl, which is the criterion for T-replacement recommended by the American Association of Clinical Endocrinologists guidelines, was 9%. Eighty two percent and 30% of the patients had lower free-T levels than the normal range (15.2-43.5 pg/ml) and that of men in their twenties in the Canadian data (9.3-26.5 pg/ml). Depending on the criteria of androgen deficiency, not all patients had low total-T and free-T levels. CONCLUSION: Patients suspected of having PADAM present various clinical symptoms and endocrinological aspects.

Adult↗

PubMed2003

Suppressive effect of viscous dietary fiber on elevations of uric acid in serum and urine induced by dietary RNA in rats is associated with strength of viscosity.

This study was performed to clarify how dietary fiber (DF) with different viscosities would be associated with dietary RNA metabolism. Male Wistar strain rats, four weeks old, were fed diets containing a 3% (w/w) yeast RNA and a 5% (w/w) viscous DF for five days. Viscosity of DF samples used, in order of strength, were xanthan gum (XG) > guar gum (GG) > locust bean gum (LBG) > karaya gum (KG) > pectin (PE) = arabic gum (AG) > CM-cellulose (CMC) = inulin (IN). The serum uric acid concentration in the viscous DF groups significantly decreased as compared with that in the cellulose (CL) group. The urinary excretions of uric acid and allantoin in the respective groups given AG, GG, IN, KG, PE, and XG were significantly suppressed as compared with those in the CL group. The fecal RNA excretion was markedly increased in the IN, KG, PE, and XG groups in comparison to the CL group. The DF with high viscosity significantly suppressed RNA digestion by RNase A and decreased uptakes of 14C-labeled adenosine and adenosine 5'-monophosphate (5'-AMP) in rat jejunum. The results reveal that the suppressive effect of DF on elevation of serum uric acid concentration induced by dietary RNA in rats is associated with the strength of DF viscosity. The mechanism by which this is accomplished is suggested to be attributed to the inhibitions of digestion for dietary RNA and/or absorption of the hydrolyzed compounds.

Adenosine Monophosphate↗

PubMed2003

Signet-ring cell carcinoma of the prostate effectively treated with maximal androgen blockade.

Primary signet-ring cell carcinoma (SRCC) of the prostate is very rare and has a poor prognosis, even when treated with aggressive therapy. We report herein a case of a 72-year-old man with prostatic SRCC. The patient had a tumor that extended directly to the rectum. Maximal androgen blockade was started and 20 months later, the patient was alive without evidence of recurrence. The present case of prostatic SRCC responded well to medical therapy, however, tumors can recur after a long period of time. Therefore, adjuvant therapy is recommended.

Aged↗

PubMed2003

[Nephrogenic adenoma of the bladder treated with cystectomy to control severe irritative symptoms: a case report].

A 68-year-old man was admitted to our hospital for treatment of a recurrent bladder tumor. Histological examination performed after transurethral resection of the bladder tumor (TUR-BT) revealed a nephrogenic adenoma without any evidence of malignancy. After TUR-BT, total cystectomy was performed to control severe irritative symptoms. Prolonged cystitis and intravesical pirarubicin therapy after TUR-BT may have played an etiological role. Our case is the 25th case of nephrogenic adenoma of the bladder reported in the Japanese literature.

Adenoma↗

PubMed2002

Catastrophic transition in vertical distributions of phytoplankton: alternative equilibria in a water column.

We showed a catastrophic transition between a surface maximum pattern and a subsurface maximum pattern of phytoplankton in a water column by a mathematical model considering the vertical distribution of phytoplankton and two resources, light and a limiting nutrient. In our model, we assumed that a water column consists of two layers: a complete mixing layer above a seasonal thermocline and an incomplete mixing layer below it. From numerical calculation of the model, we obtained that there are two stable vertical patterns of phytoplankton over a certain range of parameters of the model: a pattern having its maximum below the thermocline and another having its maximum above the thermocline. As other models having multiple stable equilibria, our model also exhibits a hysteresis effect and catastrophic transition when one of the parameters of the model changes continuously. These results indicate the possibility of the existence of alternative equilibria of vertical patterns of phytoplankton even if the trophic status and physical condition of the water column are similar. Moreover, the catastrophic transition between the steady states suggests one of the possible mechanisms of autumn algal blooms.

Animals↗

PubMed2002

Dietary fiber suppresses elevations of uric acid and allantoin in serum and urine induced by dietary RNA and increases its excretion to feces in rats.

This study was performed to examine the effects of several kinds of dietary fibers (DF) with different physical properties on dietary RNA metabolism. Male Wistar strain rats, 4 wk old, were fed diets with or without a 3% yeast RNA and a 5% DF (cellulose, chitin, chitosan, inulin, and xanthan gum) for 20 d (Experiment 1) or 5 d (Experiment 2). Feeding DF tested lowered the serum uric acid and allantoin concentrations and the urinary excretions of their compounds and increased the amount of RNA excreted into the feces compared with fiber-free. The water-holding capacity and nucleotide adsorption of chitin and chitosan in acidic solutions were higher than those of cellulose. The digestion rate of RNA by RNase A in vitro was found to be lower in the DF tested than in fiber-free. The decrease was remarkable in chitosan and xanthan gum. The uptakes of 14C-labeled adenosine and adenosine 5'-monophosphate (5'-AMP) in the rat jejunum were markedly decreased in regard to chitosan and xanthan gum in comparison with the fiber-free. These phenomena suggest that DF with high viscosity is more strongly associated with the suppression of RNA digestion by RNase A and the depression of the uptake of purine compounds to jejunum. The present results reveal that the elevation of serum uric acid concentration induced by dietary RNA can be suppressed by DF in rats.

Adsorption↗

PubMed2002

[Questionnaire survey on sexual behavior of Japanese males infected with sexually transmitted diseases].

In Japan, there has been a rapid increase in recent years in the incidence of sexually transmitted diseases (STD), particularly in teenagers and people in their twenties. To determine the factors causing this increase in STD, we carried out a questionnaire survey on the sexual behavior of Japanese males. The subjects were 248 male patients who were treated at our outpatient clinic. The results of the survey showed that 1) about 70% of the male patients were infected through sexual intercourse with partners who were not paid for such services; 2) the average number of partners in the past year was 5.8, and the average number of partners was highest for the teenage group and decreased with age; 3) only 29 (12.4%) of the 234 males used condoms; and 4) 192 (82.0%) of the 234 males received oral sex. The results of the survey suggest that a large "sexual network" has been formed among young Japanese people and that a large percentage of young Japanese people are engaged in unprotected sex.

Adolescent↗

PubMed2002

[A novel sustained release system for aqueous cis-platinum].

The authors devised a novel sustained release system for aqueous cis-platinum (CDDP) to study in vitro the degradability of the carrier materials and the release profile of the CDDP. We first prepared fibrin hydrogels with clinically used biomedical materials, and irradiated the gels with ultraviolet (UV)-rays to form gradually degradable drug carriers. We then loaded aqueous CDDP into the carriers under negative pressure. These prepared materials were incubated in fibrinolytic test medium at 37 degrees C for the in vitro studies. The UV-irradiated materials slowly degraded and dissolved within 10-15 days, while non-UV-treated carriers disintegrated in 4-5 days. Each carrier showed a sustained release of CDDP. Most of the CDDP delivered was revealed to be the protein-binding (larger than 10 kDa) form. Free-CDDP was almost nil. The antineoplastic efficacies of this new drug delivery system developed using an original technique are now being investigated.

Antineoplastic Agents↗

PubMed2002

[Risedronate].

Risedronate has recently been approved as a drug for osteoporosis treatment in Japan. According to its chemical structure, risedronate is designated a third generation bisphosphonate, which has potent anti-resorptive activity. Clinical studies conducted in Japan, North America and/or Europe revealed that risedronate reduces the risks of hip fractures and vertebral fractures by around 30% and around 50% compared with placebo over three years, respectively, and increases lumber spine BMD by around 5% at one year after starting treatment. In addition, risedronate produces a rapid and clinically important reduction in the risk of vertebral fracture and bone formed during risedronate treatment was histologically normal. Bone turnover markers, e.g., deoxypyridinoline, NTx, are reduced by around 40% (maximum). Although some bisphosphonates have been associated with upper gastrointestinal (GI) tract adverse events, a pooled analysis of 9 placebo-controlled clinical trials conducted outside Japan revealed no evidence that risedronate was associated with an increased frequency of adverse effects in the GI tract when compared with placebo.

English Abstract↗