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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 505 records · Page 28Linked to original sources
PubMed1994

[Tympanoplasty in cholesteatoma otitis media with normal hearing].

Thirteen cholesteatomas, with hearing within 20dB, were operated on from 1985 to 1992. Their mean age was 22.1 years, and the mean follow-up period 1.8 years. Eleven cases were pars flaccid type, and 2 cases pars tensa type. Tympanoplasties were performed by the canal down method (4 cases), the canal up method (3 cases), both transmeatal atticotomy and scutumplasty (4 cases) and both the canal down method and mastoid obliteration (2 cases). Postoperative hearing results of three averaged speech frequencies were within 20dB in 11 cases and between 20 and 30dB in 2 cases. No recurrent cholesteatoma or extrusion of columella occurred during the follow-up period. One of the cases operated on by the canal down method showed postoperative mastoid cavity problems, and one of the cases operated on by the canal up method showed retraction of the pars flaccida. These findings prompted us to operate on cholesteatoma cases with normal hearing and to recommend tympanoplasty with transmeatal atticotomy and scutumplasty.

Adolescent↗
PubMed1994

[A case of hepatoblastoma using intraarterial hepatic chemotherapy with THP-ADR].

The patient was a 2-year-old who was admitted with the diagnosis of liver tumor. The diagnosis at admission was stage III A hepatoblastoma complicated with tumor thrombosis of portal vein. Soon after the admission, the patient's general condition became deteriorated with increased ascites and severer jaundice. As the patient was considered to be in oncogenic emergency, chemotherapy with systemic administration of ADR and CDDP was started. Despite decreases in tumor marker and tumor shrinkage on imaging examinations, tachycardia and arrythmia occurred from the end of the second course of chemotherapy, suggesting ADR-induced cardiomyopathy, when the systemic administration of ADR was switched to less cardiotoxic hepatic arterial infusion of THP-ADR. Following 13 courses of intra-arterial infusion with the total dose of THP-ADR of 200 mg/m2, the tumor was found to have reduced markably in size and thus surgical resection of the tumor was performed. Our experience of this case indicates that, considering the pharmacokinetics and side effects, THP-ADR should be a very effective anti-tumor agent for intra-arterial hepatic infusion. The patient died 10 months after surgery because of multiple metastases into the brain and lungs.

Antibiotics, Antineoplastic↗
PubMed1994

[Congenital isolated tricuspid insufficiency in an elderly woman].

Isolated congenital tricuspid insufficiency due to primary malformation of the tricuspid valve is rare. The patient was a 70-years-old woman complaining of exertional dyspnea. Cardiac echo-sonography and catheterization showed severe TR with no other cardiac abnormality. At surgery, the anterior leaflet of the tricuspid valve was hypoplastic and attached to the right ventricle with shortened chorda. Tricuspid valve replacement was successfully performed with a 31 mm Carpentier-Edwards pericardial valve. The postoperative clinical course was smooth. This is the oldest known reported case of a successful operation for congenital tricuspid insufficiency.

Aged↗
PubMed1994

Ultrastructure of spontaneous glomerular lesions in syrian hamsters of APA strain.

Electron microscopic observations were carried out on the spontaneous glomerular lesions in male APA hamsters from 3 to 12 months of age. Until 6 months of age, focal expansion of mesangial region due to an increase of matrix material and mesangial cells was characteristic, and segmental thickening of capillary basement membrane and partial effacement of foot processes of podocytes were also sometimes observed. At 12 months of age, although all of these changes became more severe, the most prominent alteration was found in podocytes, which showed various degenerative changes. No deposition of amyloid fibrils was detected in any portion of the glomerulus.

Age Factors↗
PubMed1994

Age-related changes in skin color and histologic features of hairless descendants of Mexican hairless dogs.

Age-related changes in skin color and histologic features of hairless descendants of Mexican Hairless dogs were investigated and compared with those of haired descendants of Mexican Hairless dogs and Beagles. According to age, dogs studied were allotted to 4 groups: 0 to 2 weeks, 4 to 5 months, 1 to 1.5 years, and 3 to 4 years old. Skin color, histologic features, and numbers of dihydroxyphenylalanine (DOPA)-positive melanocytes were examined. The luminance values measured, using a spectrophotometer, decreased with advancing age up to 1.5 years, but they increased again at 3 to 4 years in hairless dogs. The number of DOPA-positive melanocytes in hairless dogs decreased with advancing age, whereas there were no DOPA-positive melanocytes in haired dogs and Beagles. Histologically, the epidermis of newborn hairless pups was thick. The border between the epidermis and dermis was wavy, and epidermal ingrowths were found projecting into the dermis. As hairless dogs grew older, the epidermis became thinner and flatter. Although numbers of hair follicles and sebaceous and apocrine sweat glands were apparently fewer in hairless dogs than in haired dogs and Beagles, these structures were detected at least up to 4 years of age. On the other hand, haired dogs and Beagles had a thin epidermis at birth and aging had little effect on their epidermal structures. The dermis of hairless dogs contained fewer mast cells than did that of haired dogs and Beagles.

Aging↗
PubMed1994

[An improved method for determination of C-peptide levels in serum: pretreatment of test samples with anti-insulin antibody insolubilized with magnetic particles].

RIA using anti-C-peptide antibody has been employed for determination of C-peptide in serum. However, the level by this method is a sum of the levels of C-peptide and proinsulin, because anti-C-peptide cross-reacts with proinsulin. This time we developed an improved assay for C-peptide, in which a test sample is pretreated with anti-insulin antibody to eliminate proinsulin in samples before C-peptide assay. The assay procedure is composed of 3 steps; the first is the incubation of test serum with anti-insulin antibody insolubilized with magnetic particles to form a complex of proinsulin-anti-insulin antibody, the 2nd step is the centrifugation of the mixture to eliminate the complex and the last step is the assay for C-peptide by use of RIA kit in the supernatant. The assay is simple, sensitive and reproducible. Serum C-peptide level by this method is not influenced by the presence of proinsulin in test serum, even when as high as 9 ng/ml of proinsulin is contained. This assay revealed that a patient with insulinoma had normal level of serum C-peptide in spite of the extremely high level of proinsulin.

C-Peptide↗
PubMed1994

Responses of the skin over the dorsum to sunlight in hairless descendants of Mexican hairless dogs.

Responses of the skin over the dorsum to solar UV irradiation (2 hours/d for 6 consecutive days) were investigated in hairless descendants of Mexican hairless dogs. Assessment of skin color changes, using a spectrophotometer, indicated that luminance values began to decrease from the third day of UV irradiation, reached the minimal value at 3 weeks, and almost recovered 12 weeks after completion of UV irradiation. The number of the dihydroxyphenylalanine-positive melanocytes increased significantly (P < 0.01) from the third day of UV irradiation, reached its maximal value at 2 weeks, and recovered to normal at 12 weeks after completion of UV irradiation. On the second day of UV irradiation, the epidermis became focally thick, with disarrangement of component cells that had degenerative changes. In addition, a few so-called sunburn cells with pyknotic nuclei were seen in the epidermis. On the third day of UV irradiation, apparent suntan reaction developed, and a large number of epithelial cells in the epidermis were heavily pigmented with melanin granules. At 12 weeks after completion of UV irradiation, the epidermis appeared almost normal. On the other hand, significant changes were not detected in the dermis throughout the study.

Animals↗
PubMed1993

[Evaluation of the potential benefit of computer-aided diagnosis (CAD) for lung cancer screenings using photofluorography: analysis of an observer study].

To evaluate the potential benefit of computer-aided diagnosis (CAD) in lung cancer screenings using photofluorographic films, we performed an observer test with 12 radiologists. We used 60 photofluorographic films obtained from a lung cancer screening program in Yamaguchi Prefecture (30 contained cancerous nodules and 30 had no nodules). In these cases, our current automated detection scheme achieved a sensitivity of 80%, but yielded an average of 11 false-positives per image. The observer study consisted of three viewing conditions: 1) only the original image (single reading), 2) the original image and computer output obtained from the current CAD scheme (CAD 1), 3) the original image and computer output obtained from a simulated improved CAD scheme with the same 80% true-positive rate, but with an average of one false-positive per image (CAD 2). Compared with double reading using independent interpretations, which is based on a higher score between two single readings, CAD 2 was more sensitive in subtle cases. The specificity of CAD was superior to that of double reading. Although CAD 1 (Az = 0.805) was inferior to double reading (Az = 0.837) in terms of the ROC curve, CAD 2 (Az = 0.872) significantly improved the ROC curve and also significantly reduced observation time (p < 0.05). If the number of false positives can be reduced, computer-aided diagnosis may play an important role in lung cancer screening programs.

Humans↗
PubMed1993

Cyclic AMP binding to the amphibian oocyte plasma membrane: possible interrelationship between meiotic arrest and membrane fluidity.

Cyclic AMP, which maintains the vertebrate oocyte in prophase arrest under physiological conditions, exhibits specific and saturable binding to the cytoplasmic face of the prophase-arrested Rana pipiens oocyte plasma membrane. Scatchard type analyses of [3H]cAMP binding to isolated plasma membranes indicate a single class of binding sites with a Kd = 19.3 +/- 7.0 nM at cAMP concentrations below 10(-6) M and additional low affinity site(s) and/or non-specific binding at concentrations above 10(-6) M. Photoaffinity labeling of prophase oocyte plasma membranes with [32P]-8-N3cAMP demonstrates cAMP/cGMP-displacable binding of 8-N3[32P]cAMP to a 100-110 kDa peptide doublet. Plasma membrane fluidity was monitored by electron spin resonance in isolated plasma-vitelline membranes using a 5-doxyl stearic acid probe. Exogenous dibutyryl cAMP (dbcAMP) produces an increase in membrane fluidity within minutes and blocks and/or reverses the progesterone-induced decrease in plasma membrane fluidity. The dbcAMP concentration that produced half-maximal fluidity increase (10 microM) corresponds to the half-maximal inhibiting dose of dbcAMP for progesterone induction of meiosis. Cholera toxin, which elevates intracellular cAMP and blocks meiosis, also increases membrane fluidity and inhibits progesterone-induced decrease in membrane fluidity. Elevated levels of intracellular cAMP thus appear to maintain meiotic arrest by binding to specific plasma membrane site(s) and maintaining the plasma membrane in a relatively fluid state. The progesterone-induced fall in intracellular cAMP first reported in Rana thus appears to be responsible for the progesterone-induced increase in membrane fluidity and further suggests that the change in membrane order is essential for the resumption of the meiotic divisions.

Affinity Labels↗
PubMed1993

Transcription factor TFIIB sites important for interaction with promoter-bound TFIID.

Transcription initiation factor TFIIB recruits RNA polymerase II to the promoter subsequent to interaction with a preformed TFIID-promoter complex. The domains of TFIIB required for binding to the TFIID-promoter complex and for transcription initiation have been determined. The carboxyl-terminal two-thirds of TFIIB, which contains two direct repeats and two basic residue repeats, is sufficient for interaction with the TFIID-promoter complex. An extra 84-residue amino-terminal region, with no obvious known structural motifs, is required for basal transcription activity. Basic residues within the second basic repeat of TFIIB are necessary for stable interaction with the TFIID-promoter complex, whereas the basic character of the first basic repeat is not. Functional roles of other potential structural motifs are discussed in light of the present study.

Amino Acid Sequence↗
PubMed1993

Archaebacterial lipids: highly proton-impermeable membranes from 1,2-diphytanyl-sn-glycero-3-phosphocholine.

Unlike ordinary glycero-lipids such as egg-yolk lecithin, 1,2-diphytanyl-sn-glycero-3-phosphocholine, which was employed as a model lipid of archaebacterial acidophiles, gave liposomal membranes which were highly resistant to proton permeation in a wide temperature range (about 10-50 degrees C); the permeability coefficient and activation energy of the flux were 0.7 x 10(-5) cm/s at 20 degrees C and 24.5 kcal/mol, respectively. The high resistance to proton flow was attributed to a fluid and bulky isoprenoid chain-layer of the membrane.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Results of vascularized joint allograft under immunosuppression with cyclosporine.

The effects of cyclosporine (CsA), a strong immunosuppressive drug, on vascularized allogeneic joint transplantations were examined. An orthotopical transplant model of a vascularized knee joint allograft was developed using inbred DA and Lewis rats to investigate the fate of grafts following withdrawal of short-term immunosuppression compared to continuous immunosuppression with CsA. Five isograft controls acquired solid bone union at both femur and tibia sites within 4 weeks, and joint function as skeletal support was maintained until 25 weeks. Without immunosuppression, ten allografts were severely rejected within the first week, and joint destruction occurred immediately. Twenty-five short-term immunosuppressed rats acquired solid union, but, after withdrawal of immunosuppression, grafted joints showed gradual rejection and were destroyed due to pathological fractures or joint instability, although partial revascularization from the recipient occurred. Ten allografts under continuous immunosuppression at a dose of 10 mg/kg/day showed no rejection and remained viable for 12 weeks postoperatively, but thereafter all rats died. Death was considered to be a side effect of CsA. Fifteen animals, under continuous immunosuppression at a dose of 5 mg/kg/day, showed no rejection except in the bone marrow; the grafted joint function was not effected until 25 weeks. Continuous treatment with low and nontoxic doses (5 mg/kg/day) of CsA was necessary to maintain the functions of the grafted joint.

Animals↗
PubMed1993

Simulation studies of data classification by artificial neural networks: potential applications in medical imaging and decision making.

Artificial neural networks are being investigated in the field of medical imaging as a means to facilitate pattern recognition and patient classification. In the work reported here, the effects of internal structure and the nature of input data on the performance of neural networks were investigated systematically using computer-simulated data. Network performance was evaluated quantitatively by means of receiver operating characteristic analysis and compared with the performance of an ideal statistical decision maker. We found that the relatively simple neural networks investigated in this study can perform at the level of an ideal decision maker. These simple networks were also found to learn accurately even when the training data are extremely unbalanced with respect to the prevalence of actually positive cases and to differentiate input data patterns by recognizing their unique characteristics.

Computer Simulation↗
PubMed1993

Involvement of Cl- transport in forskolin-induced elevation of endocochlear potential.

To determine the possible involvement of Cl- transport in the forskolin-induced endocochlear potential (EP) elevation, the effect of forskolin on the EP was examined in Cl(-)-free artificial perilymph (aPL) as well as in the presence of Cl- channel blockers. The perfusion of scala vestibuli (SV) with forskolin (200 microM) dissolved in Cl(-)-free aPL failed to produce an EP elevation, while SV perfusion of forskolin dissolved in normal aPL elevated the EP. The application of DPC and IAA-94 (blockers of cAMP-activated Cl- channel) into SV completely suppressed the forskolin-induced EP elevation, while niflumic acid (a Ca(2+)-activated Cl- channel blocker) failed to do so. IAA-94 applied into scala tympani (ST) did not suppress this EP elevation. The results suggest that adenylate cyclase may modulate the EP by changing Cl- transport between SV and scala media (SM) across Reissner's membrane.

Adenylyl Cyclases↗