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Biomedical subjects

Y Yoshikawa

Publications and source records attributed to Y Yoshikawa.

At least 55 records · Page 3Linked to original sources
PubMed2001

Immunolocalization of proliferating cell nuclear antigen (PCNA) in cynomolgus monkey (Macaca fascicularis) testes during postnatal development.

The age-related distribution of proliferating cell nuclear antigen (PCNA) in the testes of cynomolgus monkeys (Macaca fascicularis) during postnatal development was detected using light-microscopic immunohistochemistry. In neonatal testes, some PCNA-positive spermatogonia, Sertoli cells, peritubular cells, and Leydig cells were detected. In early infantile testes, only a few of these cell types were positive. In late infantile testes, the numbers of positive cells were greater than in the earlier developmental stages. In pubertal testes, the numbers of positive spermatogonia, spermatocytes, Sertoli cells, peritubular cells, and Leydig cells were considerably higher. In adult testes, a larger percentage of spermatogonia and spermatocytes was positive, and peritubular cells and Leydig cells were occasionally positive; secondary spermatocytes, spermatids, and Sertoli cells were not positive. We concluded that immunolocalization of PCNA can serve as a tool for studying proliferation status in developing testes of cynomolgus monkeys. A relatively low proliferative activity in early infantile testes and a remarkable increase of proliferative activity in pubertal testes correlate with the fluctuations of steroidogenic functions during postnatal development in cynomolgus monkeys.

Aging↗
PubMed2001

Self-assembled pearling structure of long duplex DNA with histone H1.

We report that complexes of giant DNA molecules with histone H1 proteins form a pearl necklace-like structure when the complexes are prepared by natural dilution from a high-salt solution (2 M NaCl) to a low-salt solution (0.2 M and 50 mM NaCl). We performed real-time observations on the conformational changes of individual T4 phage DNA (166 kb) molecules in bulk solution by fluorescence microscopy. To identify H1-binding regions on individual DNA molecules, we also performed immunofluorescence microscopic observations on the DNA-H1 complex spread on a glass surface. It was found that histone H1 binds DNA in a highly co-operative manner and is accompanied by local folding of the DNA. On the basis of the experimental observations and a theoretical simulation, we propose a self-assembling mechanism for the pearling structure.

Bacteriophage T4↗
PubMed2001

Dose-related cellular effects of platelet-derived growth factor-BB differ in various types of rabbit tendons in vitro.

Cellular responsiveness to growth factors that can affect tendon healing may be site-specific. We have compared the dose-response effects of platelet-derived growth factor-BB (PDGF-BB) on proteoglycan, collagen, noncollagen protein and DNA synthesis between intrasynovial intermediate and proximal segments of deep flexor tendons, and extrasynovial peroneal tendons of rabbits during short-term cultures. PDGF-BB stimulated matrix and DNA synthesis of the three types of tendon segments in a dose-dependent manner in the range from 0.1 to 100 ng/mL. PDGF-BB stimulated collagen synthesis and noncollagen protein synthesis (calculated from LogED50) in proximal intrasynovial tendon segments more than in extrasynovial peroneal tendon segments, and DNA synthesis less in proximal than in intermediate intrasynovial tendons. However, the estimated maximal stimulations (Emax) by PDGF-BB were similar in the three types of tendon segments. These findings show that PDGF-BB stimulates DNA and matrix synthesis differently in various types and regions of tendons during short term explant culture and suggests that there may be differences in cellular responsiveness during tendon healing.

Animals↗
PubMed2001

A new method of laparoscopic cholecystectomy using three trocars combined with suture retraction of gallbladder.

BACKGROUND AND PURPOSE: Since the establishment of laparoscopic cholecystectomy (LC) for benign gallbladder lesions, the four-trocar method has been the standard procedure. However, the fourth trocar generally is used just for fundic retraction of the gallbladder. We have developed a three-trocar method for LC and performed it in 132 patients. PATIENTS AND METHODS: After the creation of the pneumoperitoneum, the first 10-mm trocar sheath was inserted in the subumbilicus for the endoscope, the second 5-mm trocar in the epigastric paramedian point for the working port, and the third 5-mm trocar in the subcostal area for grasping forceps. Monofilament nylon with a straight needle was inserted through the right 7th intercostal space in the anterior axillary line, and the seromuscular layer of the gallbladder fundus was punctured and retracted toward the anterior abdominal wall. After that, usual cholecystectomy was performed. RESULTS: Among the 132 patients who underwent the three-trocar method, 10 cases (8%) needed a fourth trocar. No patient was converted to open cholecystectomy. There were no significant differences in the operating time, the length of hospital stay after the operation, or the use of analgesics between the three-trocar and the four-trocar methods. No major complication was recognized. CONCLUSION: This method also has cosmetic advantages. Therefore, we believe this method might be recommended for LC.

Cholecystectomy, Laparoscopic↗
PubMed2001

Cryopreservation-induced acrosomal vesiculation in live spermatozoa from cynomolgus monkeys (Macaca fascicularis).

BACKGROUND: Cryopreserved spermatozoa are known to undergo accelerated capacitation and require a shorter incubation time for fertilization. However, details of their acrosomal membranes following cryopreservation remain unclear. METHODS: Percoll density gradient centrifugation was used to remove dead spermatozoa; thus >90% live spermatozoa were recovered after cryopreservation, and acrosomal status was compared among non-incubated and incubated fresh and cryopreserved spermatozoa. RESULTS: Transmission election microscopy (TEM) using microwave methods and fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) staining revealed that 21.1 and 61.6% respectively of non-incubated, cryopreserved spermatozoa were intact, whereas 97.6% (TEM) or 91.9% (FITC-PSA) of non-incubated fresh spermatozoa were intact. TEM revealed that 28.8% of the cryopreserved spermatozoa were swollen, and probably included among those counted as intact by FITC-PSA staining. The non-incubated cryopreserved spermatozoa had fused plasma and outer acrosomal membranes, and 36.4% of them had vesiculation when observed by TEM. FITC-PSA staining indicated that 22% of the live spermatozoa were acrosome reacted. CONCLUSIONS: Acceleration of the acrosome reaction was evident by both TEM and FITC-PSA. Incubation of cryopreserved spermatozoa for 2 h accelerated vesiculation to a state similar to that of fresh spermatozoa that had been incubated for 8 h. These results reveal that in cryopreserved spermatozoa, the process of acrosome reaction begins before incubation.

Acrosome↗
PubMed2001

Rat cardiac contractile dysfunction induced by Ca2+ overload: possible link to the proteolysis of alpha-fodrin.

The aim of the present study was to examine the mechanisms of Ca2+ overload-induced contractile dysfunction in rat hearts independent of ischemia and acidosis. Experiments were performed on 30 excised cross-circulated rat heart preparations. After hearts were exposed to high Ca2+, there was a contractile failure associated with a parallel downward shift of the linear relation between myocardial O(2) consumption per beat and systolic pressure-volume area (index of a total mechanical energy per beat) in left ventricles from all seven hearts that underwent the protocol. This result suggested a decrease in O(2) consumption for total Ca2+ handling in excitation-contraction coupling. In the hearts that underwent the high Ca2+ protocol and had contractile failure, we found marked proteolysis of a cytoskeleton protein, alpha-fodrin, whereas other proteins were unaffected. A calpain inhibitor suppressed the contractile failure by high Ca2+, the decrease in O(2) consumption for total Ca2+ handling, and membrane alpha-fodrin degradation. We conclude that the exposure to high Ca2+ may induce contractile dysfunction possibly by suppressing total Ca2+ handling in excitation-contraction coupling and degradation of membrane alpha-fodrin via activation of calpain.

Animals↗
PubMed2001

Application of pressure-controlled colon delivery capsule to oral administration of glycyrrhizin in dogs.

A colon delivery system has been used to improve the bioavailability of glycyrrhizin, a glycoside of glycyrrhetic acid. The bioavailability of glycyrrhizin is low when administered in conventional oral galenic dosage forms because glycyrrhizin is enzymatically hydrolysed both in the stomach and in the intestine. It was reasoned that if large amounts of glycyrrhizin were directly delivered to the colon, enzymatic activity should be reduced due to saturation so that intact glycyrrhizin could be absorbed into the systemic circulation. Based on this assumption, pressure-controlled colon delivery capsules (PCDCs) were used as a colon delivery system. Eight types of glycyrrhizin solution were prepared and were introduced into PCDCs. After oral administration of the test PCDCs to beagle dogs, blood samples were obtained over 24 h and plasma glycyrrhizin concentrations were measured by an HPLC method. With PCDCs containing aqueous glycyrrhizin and propylene glycol solutions, plasma glycyrrhizin levels were extremely low and the bioavailabilities of glycyrrhizin were 0.6% and 0.4%, respectively. When Labrasol was added to both types of glycyrrhizin solution, the bioavailability was improved to 4.6% for aqueous solution and 3.8% for propylene glycol solution. When a surfactant, Polysorbate 80, was added in combination with Labrasol, synergistic effects were not obtained. Furthermore, dose-dependent effects of Polysorbate 80 were not obtained. Labrasol, which is a component of self-emulsifying drug delivery systems (SEDDS), has been shown to strongly improve the bioavailability of glycyrrhizin from the colon.

Administration, Oral↗
PubMed2001

Application of Eudragit P-4135F for the delivery of ellagic acid to the rat lower small intestine.

Based on the assumption that the delivery of ellagic acid to its site of action would show an antiinflammatory activity in inflammatory bowel disease (IBD), we have prepared microspheres using a new pH-sensitive polymer, Eudragit P-4135F (P-4135F), to deliver ellagic acid to the lower small intestine in rats. The microspheres were spherical in shape and the mean diameters were approximately 100-150 microm. The amount of ellagic acid released from the microspheres decreased by increasing the formulated amount of P-4135F. The release characteristics of ellagic acid were pH-dependent. By considering the factors loading efficiency and microsphere particle size distribution, ellagic acid-2 microspheres (P-4135F/ellagic acid = 1.65) were selected for further investigation. In a dissolution study, more than 95% ellagic acid was released within 0.5 h in pH 7.4 and 8.0 buffers. The release percent of ellagic acid was less than 40% in pH 6.8 and 7.0 and was less than 10% in pH 5.6 and 5.9. To observe the dissolution sites of the microspheres in the rat small intestine fluorescein was formulated in the microspheres as a tracer drug along with ellagic acid (50 mg kg(-1)). After intraduodenal administration of fluorescein-labelled microspheres to rats, the plasma fluorescein level started to increase at 0.5 h, by which time the microspheres had reached the middle part of the ileum. Microspheres started to dissolve within 1.0 h and the peak plasma fluorescein concentration was observed at 3.0 h, when the majority of the administered microspheres were dissolved in the terminal ileum. These results suggested that P-4135F microspheres could deliver ellagic acid to the lower part of the small intestine, and that the released ellagic acid would be distributed into the caecum and the ascending colon.

Administration, Oral↗
PubMed2001

New insulinomimetic zinc(II) complexes of alpha-amino acids and their derivatives with Zn(N2O2) coordination mode.

Zinc(II) complexes of alpha-amino acids and their derivatives with a Zn(N2O2) coordination mode were found to have in vitro insulinomimetic activity as estimated with the inhibition of free fatty acid release in isolated rat adipocytes treated with epinephrine. It was revealed that the insulinomimetic activities of zinc(II) complexes with over-all stability constants (log beta) less than 10.5 are higher than those of ZnSO4 and VOSO4. The high blood glucose level of KK-Ay mice with type 2 diabetes mellitus was lowered by daily intraperitoneal injections of a zinc(II) complex, cis-[Zn(L-Thr)2(H2O)2], for 14 d. The improvement of diabetes mellitus was confirmed with the oral glucose tolerance test.

Adipocytes↗
PubMed2001

Horizontal transmission of Toxoplasma gondii in squirrel monkeys (Saimiri sciureus).

The possibility of horizontal transmission of T. gondii was examined in squirrel monkeys. After three monkeys were inoculated perorally with 1.1-2.1 x 10(3) cysts of the T. gondii ME49, the animals were divided into two cages and maintained with one normal monkey for each cage as a cagemate. Two out of the three T. gondii-inoculated monkeys died, and the remaining one monkey was sacrificed in a moribund state one week after infection because of acute toxoplasmosis. Many T. gondii tachyzoites were recovered from broncho-alveolar lavages and were also found histopathologically in the lung, liver, spleen, kidney and lymph nodes and impression smears of tissues from the three T. gondii-inoculated monkeys by Giemsa staining. Anti-T. gondii antibody was examined by immunoblot assay in these animals, and the antibody to T. gondii major surface membrane protein (p30) could be detected after the start of experiment. Furthermore, a specific band of T. gondii NTPase gene was observed by PCR in the liver and lung of infected and cagemate monkeys, and the sequence of the second PCR products obtained from the cagemates, which were clinically normal but gave a positive result in immunoblotting assay, was exactly the same as the sequence of the NTPase gene of T. gondii ME49. These findings suggested that transmission of T. gondii from the infected monkeys to cagemates occurred easily, and since many T. gondii tachyzoites were recovered from the bronchoalveolar lavages of the three T. gondii-inoculated monkeys, we suggest that aerosol infection plays an important role for the enzootic toxoplasmosis in colonies of squirrel monkeys.

Aerosols↗
PubMed2001

Senile plaques in an aged western lowland gorilla.

Senile plaques (SPs) were found in the cerebral cortex of a 44-year-old Western lowland gorilla (Gorilla gorilla gorilla). All the SPs were obtained as dense assemblies consisting of fibrous materials by silver impregnation, but were not detected by Congo red. More SPs were detected by immunostaining for amyloid beta protein (A beta) and a half of A beta-positive-SPs were also immunoreactive for apolipoprotein E. Moreover, all SPs were immunoreactive for A beta 42 and A beta 43, but not for A beta 40. SPs also did not contain A beta precursor protein-positive structures. These findings suggested that SPs in this case were diffuse plaques. To our knowledge, this is the first report of SPs in the gorilla.

Aging↗
PubMed2001

Possible role of peripheral CD14low monocytes in the development of collagen-induced arthritis in cynomolgus monkeys (Macaca fascicularis).

The changes in levels of peripheral major lymphocyte subsets were monitored with 10 adult cynomolgus monkeys (5 females and 5 males) during the 9 weeks after immunization with chick type-II collagen in Freund's complete adjuvant. Three females and 3 males developed overt arthritis determined by swelling of small joints and increase of plasma alkaline phosphatase as well as C-reactive protein. An increase of CD16+ NK cells was observed in four non-arthritis-developed monkeys (two females and two males). There was no significant difference in the fluctuation pattern of CD4+ T cell, CD8+ T cell and CD20+ B cell levels between arthritis-developed monkeys and non-developed ones. In addition, the percentages of CD45RA+ CD4+ T cells to total CD4+ T cells, CD28- CD8+ T cells to total CD8+ T cells, and IgD- B cells to total B cells did not significantly differ between them. On the other hand, a significant increase was demonstrated in CD14-positive cells at 3 weeks after immunization in only arthritis-developed monkeys regardless of sex. The expression of CD14 antigen on the surface of increased cells was low in comparison with those appearing in blood obtained before immunization. In addition, increased CD14low cells showed no response to LPS stimulation. However, there was no significant difference in antibody titer to both chick type-II and monkey type-II collagen between arthritis-developed monkeys and non-developed ones. These results suggest that an increase in number of CD14low monocytes with immature function might be a part of the autoimmune response, and that the appearance of these cells is of pathogenic importance in the arthritic process in cynomolgus monkeys regardless of the production of autoantibody.

Alkaline Phosphatase↗
PubMed2001

Results of hyperamplification of centrosomes in naturally developing tumors of dogs.

OBJECTIVE: To evaluate results of centrosome hyperamplification in naturally developing tumors of dogs. SAMPLE POPULATION: Tumor specimens from 9 dogs with tumors (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, myxosarcoma, and mammary gland tumor) and 2 canine osteosarcoma cell lines. PROCEDURE: 3 antibodies for centrosome proteins (ie, anti-gamma-tubulin, anti-BRCA1, and anti-pericentrin) were used for immunohistochemical analysis. Double immunostaining for centrosomes was used to confirm the specificity of these antibodies for centrosomes. Mutational analysis of the canine p53 gene was carried out by polymerase chain reaction-single-strand conformation polymorphism analysis, and expression of canine MDM2 protein was evaluated by use of immunohistochemical analysis, using anti-MDM2 antibody. RESULTS: Immunohistochemical analysis of dog osteosarcoma cell lines with apparent aneuploidy revealed frequent hyperamplification of centrosomes in the osteosarcoma cell lines. Similar hyperamplified centrosomes were detected in the tumor tissues from all of the 9 tumors. The frequency of cells with hyperamplified centrosomes (3 to 20/cell) in each tumor tissue ranged from 9.50 to 48.1%, whereas centrosome hyperamplification was not observed in normal lymph nodes from these dogs. In 8 of the 9 tumors, mutation of p53 gene or overexpression of MDM2, or both, was detected. CONCLUSIONS AND CLINICAL RELEVANCE: Various types of naturally developing tumors in dogs often have hyperamplification of centrosomes associated with chromosome instability. Hyperamplification of centrosomes is a novel tumor marker for use in cytologic and histologic examinations of clinical specimens obtained from dogs.

Animals↗
PubMed2001

Expression of Fas ligand in gastric carcinoma relates to lymph node metastasis.

Tumors may escape a host's immune response by means of various mechanisms. The Fas (CD95/APO-1)/Fas ligand (FasL) system is one of the major apoptotic pathways. Recently, it has been reported that tumor cells can express FasL, induce apoptosis in tumor infiltrating lymphocytes, and thus can escape host immune surveillance. In gastric carcinoma, tumor progression by way of the lymphatics is often seen, and lymph node metastasis is a critical factor influencing the recurrence of cancer and its prognosis. We, therefore, investigated the relationship between the expression of FasL and the lymphatic spread of gastric carcinoma. FasL-expression was examined by an immunohistochemical method using 100 surgically resected gastric carcinomas and 55 metastatic lymph nodes. Apoptotic cells among tumor infiltrating T lymphocytes were detected by T lymphocyte staining and the terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick end labeling (TUNEL) method in a series of sections of metastatic lymph nodes. FasL-expression was detected in 86% of primary lesions and 71% of metastatic lymph nodes. In cases with high levels of FasL-expression, the observed expression of lymph node metastases was significant (p=0.047). Moreover, FasL-positive cases with both primary lesions and metastatic lymph nodes showed also distant lymph node metastasis beyond the regional lymph nodes (p=0.030). Apoptosis among tumor infiltrating T lymphocytes was more frequently seen in FasL-positive lesions (p=0.057). Furthermore, patients with FasL-negative primary lesions tended to exhibit longer survival times than patients with FasL-positive primary lesions. The results suggest tumor escape through the lymphatic pathway via FasL-expression in gastric carcinomas.

Adenocarcinoma↗
PubMed2001

[Laparoscopic radical prostatectomy--initial 10 cases].

PURPOSE: We report the clinical results and efficacy of laparoscopic radical prostatectomy for localized prostate cancer. PATIENTS AND METHODS: Between December, 1999 and June, 2000 we performed transperitoneal laparoscopic radial prostatectomy on 10 patients with T1 or T2 organ confined prostate cancer according to the techniques as described by Guillonneau et al. Different points were as follows: 1) We placed double J catheters during surgery to prevent ureteral injury. 2) We treated dorsal vein complex using an Endo-GIA-stapler. 3) We dissected the bladder neck from the prostate using an ultrasound scalpel in the manner to preserve the bladder neck. RESULT: We could not completed laparoscopic prostatectomy on two patients because of massive bleeding from dorsal vein and consuming too much time to suture urethra-bladder anastomosis. The average operating time in all cases was 8.1 hours including 1.8 hours in laparoscopic pelvic lymphadenectomy. The average estimated blood loss in all cases was 859 ml. There were 2 surgical complications with bladder injury and port site hernia. The histological examination revealed prostate cancer; pT2pNO in 8, pT3pNO in 2. The surgical margin and lymph nodes were negative in all patients. The duration of an indwelling catheter ranged from 5 to 40 days mean 17 days. The duration to recovery of normal micturition was 6 to 90 days, mean 40 days. CONCLUSION: Long-term follow-up and extensive studies are necessary to evaluate the efficacy of this procedure. It might provide shorter duration of an indwelling catheter and earlier recovery of normal micturition as compared with the conventional open surgery.

Aged↗
PubMed2001

Specific gravity of whole blood in cynomolgus monkeys (Macaca fascicularis), squirrel monkeys (Saimiri sciureus), and tamarins (Saguinus labiatus) and total blood volume in cynomolgus monkeys.

Blood collection is a common laboratory procedure in animal experiments. The purpose of this study is to establish baseline data for two essential hematologic parameters, total blood volume (TBV) and specific gravity of blood (SGB), of nonhuman primates. The SGB was determined by dropping samples of whole blood into cupric sulfate solution. The values for the mean SGB +/- 1 standard deviation are: cynomolgus monkeys, 1.0526 +/- 0.0019 [males (n = 39), 1.0531 +/- 0.0017; females (n = 48), 1.0522 +/- 0.001]; squirrel monkeys, 1.0555 +/- 0.0037 [males (n = 56), 1.0581 +/- 0.0027; females (n = 76), 1.0536 +/- 0.0032]; and tamarins, 1.0582 +/- 0.0020 [males (n = 13), 1.0582 +/- 0.0023; females (n = 17), 1.0581 +/- 0.0018]. To determine the TBV, blood was collected in tubes containing 1.5 mg EDTA after intravenous injection of Evans Blue solution. The TBV was obtained after correcting for the hematocrit and the dilution factor of the Evans Blue solution. The formulae were established to estimate TBV by referring to body weight (BW). There was no significance between TBV and BW in male monkeys weighing more than 6 kg.

Animals↗
PubMed2001

[Reconstruction of the right ventricular outflow tract in patients undergoing the Ross procedure].

Since 1992, 46 patients have undergone the Ross procedure. Of these, a pulmonary homograft was used for reconstruction of the RVOT in 16, and a tailored heterologous or autologous pericardial roll tube in 9. In the remaining 21, the autologous tissues were used as a posterior wall of the channel, placing another patch (bearing a monocusp in 14) anteriorly. All the patients survived the procedure. Reoperation has been needed thus far in one for infection of the prosthetic patch placed at the right ventricular outflow tract, and catheter intervention in 2 for mild obstruction across the channel. On the basis of postoperative catheterization, presence or absence of a valvar structure across the right ventricular outflow tract did not affect ejection fraction of the right ventricle and right atrial pressure. In contrast, right ventricular end diastolic volume was smaller, as well as diastolic pulmonary arterial pressure was higher, when a competent trifoliate valve was provided at the right ventricular outflow tract. An incision to the ventricular septum for subaortic stenosis, coronary arterial obstruction preoperatively present, and age at operation younger than 2 years old, were unfavourable factors affecting right ventricular performance. We conclude that, in the majority of our patients, right ventricular performance was unlikely impaired even without a competent pulmonary valve. Use of a homograft, however, could be preferred in a selected group of patients with deleterious circumstances on the postoperative circulation.

Adolescent↗