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Biomedical subjects

T Otani

Publications and source records attributed to T Otani.

At least 163 records · Page 9Linked to original sources
PubMed1994

Late mechanical stability of the proximal coated AML prosthesis.

Micromotion of a bone-ingrown anatomic medullary locking (AML) femoral component was evaluated in a specimen retrieved from a 66-year-old man who died 4 years following total hip replacement. Radiographic signs suggested bone ingrowth into the proximal porous coating, but a radiolucent line surrounded by a sclerotic line was present around the distal stem. Both torsional and axial loading to physiologic levels elicited minimal micromotion at the proximal bone-prosthesis interfaces. However, medial-lateral micromotion at the distal tip was found to be as high as 44 microns with axial load. An AML femoral component of similar design was inserted into the opposite normal femur using the cementless press-fit technique originally used for the implanted specimen. Micromotion proximally was much greater in the freshly implanted systems in response to both torsional and axial loading than in the bone ingrown specimen. However, distal medial-lateral micromotion was much greater for the bone-ingrown stem. These findings show that bone ingrowth provides rigid fixation of the implant to bone; however, flexibility of the femur causes increased micromotion of the femur around the smooth distal stem despite initial tight distal fit.

Aged↗
PubMed1994

Monoclonal antibody raised against apoprotein of C-1027: effect on biochemical and biological activities of the holoantibiotic.

A monoclonal antibody raised against C-1027 apoprotein recognized not only the apoprotein, but also the holoantibiotic (Antibiotic C-1027) almost equally. Among the biochemical and biological activities of the holoantibiotic, the antibody inhibited the aminopeptidase activity and the cytotoxicity to Ehrlich carcinoma cells in cultures, but not the DNA-cleaving activity in vitro. The immunohistogram, using this antibody, of Ehrlich carcinoma cells that had been exposed to the holoantibiotic suggested penetration of the holoantibiotic into target cells.

Aminoglycosides↗
PubMed1994

[Percutaneous renal cyst puncture with CO2 instillation therapy].

Ultrasound-guided percutaneous puncture of renal cysts replaced by CO2 was performed on 9 renal cysts of 6 patients from May 1993 through September 1993. Puncture and aspiration of cysts was performed using a 5.5 Fr one-step fluid drain kit (pig tail stent) under ultrasonography inspection. Aspirated volume of cyst contents was 15-292ml (mean 115 ml), and the instilled CO2 volume was 15-150 ml (mean 73 ml). All patients were checked by CT scan. In one month, the reduction rate of cyst volume was 46-84% (mean 69%) and lumbago, their chief complaint, was improved in all patients. No complications were observed in patients treated by CO2 instillation. Although long-term followup is needed to draw a definite conclusion, this therapy may be useful for benign renal cystic lesions.

Aged↗
PubMed1993

Reversal of methotrexate-induced folate pool depletion by thymidine in a human leukemia cell line in vitro.

In an in vitro study using a human monocytic leukemia cell line, U-937, the effects of interferon-gamma (IFN-gamma) in combination with the antifolate methotrexate and the role of thymidine introduced as a biochemical modulator were investigated. Methotrexate alone or in combination with INF-gamma was found to enhance the induction of morphologic and functional monocytic differentiation in the U-937 cell line. Various cellular effects with the addition of thymidine to the medium with methotrexate and IFN-gamma were studied. Enhanced inhibition of cell growth and perturbation of the cell cycle were noted when methotrexate and IFN-gamma were used in combination, but not when methotrexate was used alone. The reduction of cellular folate by methotrexate was also enhanced in combination with IFN-gamma. Cell cycle delay, resulting in cell growth inhibition of folate depletion, caused the induction of differentiation in U-937 cells, which was found to be greater with methotrexate + IFN-gamma than with methotrexate alone. Cellular differentiation, as assessed by nitroblue tetrazolium reduction assay, indirect immunofluorescence and morphology, showed better effects towards the differentiation of U-937 cells when the agents were used in combination. However, addition of thymidine to the medium was found to cancel all the aforementioned effects. The addition of thymidine to the medium also caused reversal of the inhibitory effect of methotrexate and IFN-gamma on cell growth and repletion of the endogenous folate level. Repletion of the folate level by exogenous thymidine is a new possibility for the role of the thymidine in cellular growth.

Antibodies, Monoclonal↗
PubMed1993

Crystallization and preliminary X-ray diffraction studies of C-1027-AG, the apoprotein of the macromolecular antitumor antibiotic C-1027 from Streptomyces globisporus.

C-1027-AG, the apoprotein of the macromolecular antitumor antibiotic C- 1027, isolated from Streptomyces globisporus, was crystallized by the vapor-diffusion procedure using 2-methyl-2,4-pentanediol as a precipitant. The crystals belong to the orthorhombic system, space group P2(1)2(1)2(1), with unit-cell dimensions a = 55.1, b = 61.3 and c = 79.1 A. Assuming that the asymmetric unit contains two or three molecules, the V(m) value is calculated as 3.2 or 2.1 A(3) Da(-1), respectively. A total of 7630 independent reflections was obtained up to 2.5 A resolution with synchrotron radiation, the merging R factor being 0.077 for 24 713 measurements.

Journal Article↗
PubMed1993

Strain distribution in the proximal femur with flexible composite and metallic femoral components under axial and torsional loads.

This study investigated strain distribution changes in the proximal femur after implantation of a flexible composite femoral component (carbon composite material, modulus of elasticity = 18.6 GPa), a titanium alloy implant (E = 100 GPa), and a stainless steel implant (E = 200 GPa). Transverse as well as longitudinal strain was measured using bipolar strain gauges at eight locations on the proximal femur under both physiologic axial (1000 N and 2000 N) and physiologic torsional (10 N-m and 20 N-m) loads. Under axial load, longitudinal compressive strain at the calcar region was significantly greater in intact femurs and the carbon composite stem specimens than in the two metal stem specimens. The difference between intact femurs and the carbon composite stem specimens was not significant. Stress shielding in the proximal lateral region of the femur, however, was still apparent even in the carbon composite stem specimens. Without seating of the stem collar on the femoral neck, longitudinal compressive strain was not generated at the calcar region, and transverse tensile strain at this region was increased. With conventional implant design, the stem collar was still necessary even in the flexible composite stem to provide near normal longitudinal compressive strain in the calcar region. Under torsional load, proximal strain in intact femurs was small and the proximal strain levels observed after either carbon composite or titanium alloy stem implantation were greater than strain levels before implantation. It seemed unlikely that torsional stress relief played a significant role in proximal bone loss after total hip arthroplasty. Both longitudinal and transverse strains at the calcar region under torsional load were significantly greater in the carbon composite stem specimens than in both intact femurs and the titanium alloy stem specimens, suggesting that these abnormally high proximal stresses may cause high proximal micromotion of the implant, and even bone fracture. Proximal implant design seems to be of paramount importance with flexible composite femoral components to avoid excessive proximal stress concentration under torsional load and to provide near normal strain distribution in the proximal femur.

Alloys↗
PubMed1993

Clinicopathological features and endoscopic diagnosis of superficial early adenocarcinomas of the large intestine.

From October 1987 to March 1991, 21 (8%) superficial early cancers were found among 256 early colorectal cancers (Dukes A and B1). Superficial early cancers were defined as early cancers less than 3 mm in height. These tumors were found scattered throughout the large intestine and were often observed as reddish spots, which were easily overlooked without careful observation. Histologically, 19 (90%) of them were well-differentiated adenocarcinomas, and five (24%) of them reached the submucosal layer. Eighteen (86%) of them were not associated with adenoma.

Adenocarcinoma↗
PubMed1993

Effects of femoral component material properties on cementless fixation in total hip arthroplasty. A comparison study between carbon composite, titanium alloy, and stainless steel.

Carbon-fiber-reinforced-carbon composite material is an attractive implant material because its modulus of elasticity can be made similar to that of cortical bone. This study investigated the effect of femoral prosthesis elastic modulus on cementless implant fixation. Distal, as well as proximal, relative micromovements between implant and bone were measured in two testing protocols (axial-load and torsional-load), comparing identically shaped carbon composite (modulus of elasticity = 18.6 GPa), Ti6Al4V (100 GPa), and 630 stainless steel (200 GPa) prostheses. In the axial-load test, proximal mediolateral micromotions were significantly larger in the flexible composite stem than in the two metals. In the torsional-load test, rotational micromotions and "slop" displacements in the flexible stem were significantly larger proximally and significantly smaller distally than in the two metals. While these results suggest that proximal stress transfer may be improved by a flexible stem, they raise the possibility of increased proximal micromotion, and suggest that improved proximal fixation may be necessary to achieve clinical success with flexible composite femoral components.

Alloys↗
PubMed1993

A new antibiotic, cypemycin. Taxonomy, fermentation, isolation and biological characteristics.

A new peptide antibiotic, cypemycin, with a molecular weight of 2,097 (M+H), was isolated from the culture broth of Streptomyces sp. OH-4156. The antibiotic possesses cytocidal activity against P388 leukemia cells in vitro at a concentration of 1.3 microgram/ml (IC50 values), and the antibiotic showed antimicrobial activities against Micrococcus luteus (MIC, 0.2 microgram/ml).

Amino Acid Sequence↗
PubMed1993

Isolation, structure determination and biological activities of a novel antifungal antibiotic, S-632-C, closely related to glutarimide antibiotics.

A new antifungal antibiotic, S-632-C, was extracted with ethyl acetate from the culture filtrate of Streptomyces hygroscopicus S-632 and isolated through a combination of column and preparative thin-layer chromatographies on silica gel. The structure of S-632-C was determined by analysis of 1H and 13C-NMR, MS, UV and IR spectra in comparison with those of S-632-A2 (9-methylstreptimidone). The signals were assigned on the basis of 2D NMR experiments, which involved 1H-1H DQF COSY, HMQC and HMBC spectral analysis. From these results, the chemical structure of S-632-C was elucidated as 6-(3,5-dimethyl-2-oxo-4,6-octadienyl)-4-carbamoylmethyl-3,4, 5,6-tetrahydro-2- pyrone. The antibiotic exhibited exclusively weak in vitro antifungal activity against Saccharomyces spp. and similar cytotoxic activity against KB carcinoma cells, as compared with the glutarimide antibiotic S-632-A2. In addition, this antibiotic had the ability to change the morphology of ras(ts)-transformed NRK cells to that of normal cells, also a characteristic S-632-A2 and B1.

Antifungal Agents↗
PubMed1993

Conformation studies on and assessment by spectral analysis of the protein-chromophore interaction of the macromolecular antitumor antibiotic C-1027.

Characterization of the secondary structure of the antitumor antibiotic C-1027 has been made from a comparison of C-1027 and its apoprotein by various analytical means. The results indicated the antibiotic to be abundant in beta-structure by measurements of Fourier-transform infrared (FT-IR) spectroscopy and the circular dichroism (CD) spectrum, and by a prediction of the secondary structure based on the amino acid sequence of the peptide. In comparison of the IR spectra of their proteins in D2O, the apoprotein exhibited a faster H-D exchange than C-1027, indicating an increase in the "non-motile parts" of the beta-sheets formed through the protein-chromophore interaction in holo-C-1027. The prediction of hydropathic index indicated the hydrophobic residues of the apoprotein to be predominantly located in the beta-sheet structures, suggesting hydrophobic interaction in the binding between chromophore and apoprotein. Further, the interaction between chromophore and apoprotein was detected by a fluorescence method. The result showed the dissociation constant (Kd) to be 6.88 x 10(-5) M, indicating that the chromophore is tightly bound to the protein moiety.

Amino Acid Sequence↗
PubMed1993

[Antibiotic prophylaxis for transurethral resection of the prostate--comparison of oral administration therapy with intravenous administration therapy].

To compare the prophylactic effect of oral and intravenous antibiotics against postoperative fever and urinary tract infection (UTI) after transurethral resection of the prostate (TUR-P), we conducted a multi-center prospective randomized study. The incidence of pyrexia over 38 degrees C was defined as the primary endpoint. One hundred and fifty patients with sterile urine before TUR-P were entered into this study. The patients were allocated randomly into the two arms; arm A cefotiam 4 g a day for 7 days, arm B tosufloxacin 300 mg a day for 7 days, based on the stratification into the 4 groups determined with/without preoperative indwelling catheters and with/without the history of preoperative UTI. Of these patients, 143 were eligible. We divided 124 patients without preoperative UTI and without indwelling catheters as the "low risk group", and the other 19 patients with preoperative UTI and/or with indwelling catheters as the "high risk group". In the low risk group, 9 patients out of 63 (14.3%) in arm A and 6 out of 61 (9.8%) in arm B had pyrexia during 7 postoperative days. The incidence of fever in arm B was 4.4% less than that in arm A and the 95% confidence limit was from -7% to 16%. In the high risk group, 4 out of 11 (36.4%) patients in arm A and none of 8 in arm B had fever but the difference was not significant. The incidence of post operative UTI in the low risk group on the 4 to 5, 9 to 12, 23 to 26 and 37 to 40 postoperative days was 8.3, 16.4, 25.0 and 23.9% in arm A and 6.7, 16.7, 29.6 and 36.7% in arm B, respectively. The prophylactic effect of oral administration of tosufloxacin is equivalent to that of the intravenous administration of cefotiam. The use of oral antibiotics is beneficial to reducing the cost of medication.

Administration, Oral↗
PubMed1993

[Clinical effects of transabdominal simple hysterectomy on micturition function].

We prospectively investigated micturition function in 68 women who were operated on by transabdominal simple hysterectomy for uterine myoma. Twelve parameters including stress urinary incontinence, obstructive symptoms, irritative symptoms, uroflow curves and amount of residue were subjectively or objectively evaluated before surgery and a mean of 4.4 months post-operatively. Though 55 patients (81%) had had one or more symptoms of micturition disorders prior to operation, surgery significantly reduced this number to 32 (47%) (p < 0.01). Hysterectomy significantly decreased the number of patients suffering from stress urinary incontinence, weak urinary stream, straining micturition, interrupted stream, urgency and frequency in the daytime. The relationship between the weight of the uterus removed and pre-operative symptoms of micturition disorders was assessed. Interrupted stream was present significantly more in the patients with a uterus weighing less than 400 grams and urgency in the patients with a uterus weighing more than 401 grams. We conclude that transabdominal simple hysterectomy is of use to improve micturition disorders pre-operatively recognized.

Adult↗
PubMed1993

Cutting errors in preparation of femoral components in total knee arthroplasty.

Cutting errors that occur during preparation of the femoral component can deter fixation in cementless total knee arthroplasty. This study evaluated the causes of femoral cutting errors and identified methods to minimize these errors. The cutting error caused by toggle of the saw blade in the guide-slot was measured with wood blocks, a cutting guide with 1.5 mm guide slots, and four kinds of saw blades (narrow and wide blades with thicknesses of standard 1.2 mm and thicker 1.4 mm). Another cause of cutting errors, relative motions between the cutting guide and distal femur due to vibration of the saw blade during bone cuts, was measured with preserved cadaver femurs. Various combined fixation methods with intramedullary rod, pins, and clamps were compared. The maximum cutting error caused by toggle of the saw blade in the slot was significantly reduced by using the thicker 1.4 mm saw blade, but the differences between wide and narrow blades in each thickness were not significant. Mean maximum cutting error at the cutting depth of 5 cm with 1.2 mm thick saw blades was 802 microns, and with 1.4 mm thick saw blades it was 488 microns. In the measurement of relative motion, fixation with only pins or clamps did not provide tight fixation and had deflections from 200 microns to more than 1 mm. The best fixation was obtained by combining fixation methods of intramedullary rod and pins or clamps. This resulted in total movement of less than 100 microns. The results of this study indicate that both toggle of the saw blade in the slot and motion of the cutting guide can cause major cutting errors. Cutting error can be minimized by using thicker saw blades and by fixing the cutting guide to the distal femur with combined fixation methods of a central rod and peripheral pins or clamps.

Bone Cements↗
PubMed1993

The effect of axial and torsional loading on strain distribution in the proximal femur as related to cementless total hip arthroplasty.

This study investigated the normal load transfer pattern in the intact proximal femur. Both longitudinal and circumferential strains at eight strain-gauge locations were measured in response to both axial loads (1,000 and 2,000 N) and torsional loads (10 and 20 N . m). Under axial loads, strain magnitudes were large in the proximal regions and decreased distally. Very high compressive longitudinal strain was generated at the surfaces of the proximal medial cortical region, yet circumferential strain at this region was relatively low. Singh osteoporosis classification and femoral head diameter significantly affected the strains in the proximal part of the femur, and femoral head offset significantly affected strain levels in the diaphysis. Under torsional loads, the magnitudes of strain were much smaller than those generated under axial loads, but they increased distally. This study suggests that the proximal part of the femur is equipped for high longitudinal strain but is not equipped to handle high circumferential strain. The diaphysis of the femur is exposed to both axial and torsional loads and is equipped to handle high longitudinal and circumferential strains. Femoral implants that generate high circumferential strain in the proximal femur and high bending stress in the diaphysis are likely to fail mechanically or cause significant bone remodeling. Femoral implants and surgical procedures should be designed to apply load to the femur in a manner in which the femur can handle it best.

Cementation↗
PubMed1992

Early depressed adenocarcinomas of the large intestine.

From January 1987 to December 1990, five cases of early depressed cancer of the large intestine were seen. Endoscopically, almost all of these tumors were located in the proximal colon and looked like a reddish depression (similar to the sucker of an octopus). Histologically, all of these cancers were well differentiated and tended to reach deeper layers at an early stage. Four (80%) of these cancers were not associated with adenoma and were thought to have arisen de novo.

Adenocarcinoma↗