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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 361 records · Page 20Linked to original sources
PubMed1997

Direct and indirect thalamic afferents arising from the vestibular nuclear complex of rats: medial and spinal vestibular nuclei.

We examined the afferent pathways and terminations in the thalamus from the medial vestibular nucleus (MVe) and the spinal vestibular nucleus (SpVe) with anterograde transport of Phaseolus vulgaris leucoagglutinin (PHAL) and retrograde transport of wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP). Following PHAL injection into the MVe, many anterogradely labeled fibers and terminal-like boutons were recognized in the central lateral nucleus of the thalamus. Sparse projections were found in the zona incerta, the ventral lateral geniculate nucleus and the compact region of the laterodorsal thalamic nucleus. When PHAL was injected into the SpVe, labeled ascending fibers ran along the lateral lemniscus forming a loose bundle, and terminated in the medial part of the rostrocaudal extent of the medial geniculate body, and the posterior and ventral thalamic nuclei. Furthermore, a few fibers projected to the central lateral nucleus. In order to confirm the indirect thalamic afferents via the spinal trigeminal nucleus, we injected WGA-HRP into the submedius nucleus of the thalamus after PHAL injection into the SpVe. Many anterogradely labeled terminal-like boutons from SpVe were recognized apposing retrogradely labeled spinal trigeminal neurons. Thus, the present results indicate the existence of dual vestibulo-thalamic pathways; a direct projection to the thalamus, and an indirect projection to the submedius nucleus via the spinal trigeminal nucleus.

Afferent Pathways↗
PubMed1997

Longer survival of rat limb allograft. Combined immunosuppression of FK-506 and 15-deoxyspergualin.

We studied the individual and synergistic effect of 3 immunosuppressive drugs, FK-506 (1 mg/kg/day), 15-deoxyspergualin (2.5 mg/kg/day) and cyclosporine (15 mg/kg/day) in a DA/Lewis rat limb allotransplantation model. 74 right hindlimb transplantations were performed. The median time for onset of rejection was 4 days in animals without immunosuppression, 37 days in animals receiving cyclosporine immunosuppression for 30 days, 61 days in animals receiving FK-506 for 30 days, 36 days in animals receiving a 30-day course of cyclosporine and, in the first 15 days, a course of 15-deoxyspergualin, and 76 days in animals receiving a 30-day course of FK-506 and 15-deoxyspergualin in the first 15 days. The combination of cyclosporine with 15-deoxyspergualin did not prolong graft survival and no synergistic effect was evident. In contrast, survival time in rat limb allografts receiving FK-506 and 15-deoxyspergualin was longer than in those receiving single FK-506 therapy. Our findings suggest a positive synergistic immunosuppressive effect with FK-506 and 15-deoxyspergualin in limb allotransplantation.

Animals↗
PubMed1997

[A case report of bilateral perilymph fistula in an adult, with literature review].

Adult bilateral perilymph fistula (PLF) is rare. We report a case of a 55-year-old man who suffered from sudden bilateral hearing loss after blowing his nose. On the first day, he also had bilateral tinnitus but no vertigo. However, he gradually developed vertigo, and nystagmus to the left side began to appear in the following days. Exploratory bilateral tympanotomies were performed and perilymph fistulas were observed at the round window niche in both ears. The round windows were obliterated with fascia of the temporal muscles. After the operation no changes were found in both sides on a pure tone audiogram even at a one-year follow-up. The literature was reviewed and several features were statistically analyzed. In the adult bilateral PLF group, the proportion of the cases in which the cause of PLF was clear was significantly higher than that in the adult unilateral PLF group, but the other clinical features were almost the same. The results suggest that in adults the occurrence of bilateral and unilateral PLF could depend on the level of pressure applied to the middle or inner ear. On the other hand, in the child PLF group, the ratio of bilateral involvement was considerably higher than that in the adult PLF group, and in most cases the PLF was associated with middle and/or inner ear malformations. Healing in the child bilateral PLF group was poor than that in the adult PLF group. Those results suggest that the etiology of bilateral PLF in children may be considerably different from that of adult PLF.

Age Factors↗
PubMed1997

Greedy Algorithms for Finding a Small Set of Primers Satisfying Cover and Length Resolution Conditions in PCR Experiments.

Selecting a good collection of primers is very important for polymerase chain reaction (PCR) experiments. Most existing algorithms for primer selection are concerned with computing a primer pair for each DNA sequence. In generalizing the arbitrarily primed PCR, etc., to the case that all DNA sequences of target objects are already known, like about 6000 ORFs of yeast, we may design a small set of primers so that all the targets are PCR amplified and resolved electrophoretically in a series of experiments. This is quite useful because deceasing the number of primers greatly reduces the cost of experiments. Pearson et al. (ISMB 1995: 285-291, 1995; Discrete Appl. Math. 71: 231-246, 1996) consider finding a minimum set of primers covering all given DNA sequences, but their method does not meet necessary biological conditions such as primer amplification and electrophoresis resolution. In this paper, based on the modeling and computational complexity analysis by Doi, we propose algorithms for this primer selection problem. These algorithms do not necessarily minimize the number of primers, but, since basic versions of these problems are shown to be computationally intractable, especially even for approximability with the length resolution condition, this is inevitable. In the algorithms, the amplification condition by a primer pair and the length resolution condition by electrophoresis are incorporated. These algorithms are based on the theoretically well-founded greedy algorithm for the set cover in computer science. Preliminary computational results are presented to show the validity of this approach. The number of computed primers is much less than a half of the number of targets, and hence is less than one forth of the number needed in the multiplex PCR.

Journal Article↗
PubMed1997

[A case report on successful coronary artery bypass grafting (CABG) for angina pectoris combined with hypothyroidism].

Coronary artery bypass grafting (CABG) for patients with ischemic heart disease and hypothyroidism contains many controversies, such as a need of preoperative thyroid replacement therapy and the influences on thyroid function and hemodynamics. A 73-year-old man with three vessel disease including left main trunk lesion was admitted for CABG. Primary hypothyroidism was diagnosed after admission because of high CPK value. The CABG was performed safely with preoperative minimal thyroid replacement and his postoperative course was uneventful. We evaluated the change of perioperative thyroid hormones. At the start of the extracorporeal (ECC), values of T3 and free-T3 decreased progressively, but the change was small. On the other hand, values of T4 and free-T4 increased after the start of ECC. It is suggested that CABG for a patient with angina and hypothyroidism can be performed safely with minimal preoperative thyroid replacement therapy.

Aged↗
PubMed1997

[Twenty cases of superior septal approach for mitral valve operation].

We experienced 20 cases of superior septal approach (SSA) for mitral valve surgery from June 1992 to December 1995. From pre-operative coronary angiography, sinus node arteries (SNAs) were grouped into three types, branched from right coronary artery (RCA: 45%), from left circumflex (LCx: 35%), and from both RCA and LCx (Bilateral: 20%). And, in diameter, they were grouped into two groups, above 1 mm (80%) and below 1 mm (20%). There were no peri-operative deaths and complications associated with SSA. In acute post operative phase, atrial fibrillation, junctional rhythm, atrial flutter, and sino-atrial block were observed, especially in patients whose SNA branched from RCA, and were above 1 mm in diameter. In late follow-up, all patients' rhythm returned to pre-operative rhythm, although some cases became bradycardia less than 60 per-minute. Bradycardia was observed in patients whose SNA branched from RCA, and were above 1 mm in diameter. There may be relationship between post operative arrhythmia and division of large SNAs originated from RCA. We concluded that SSA is safe and excellent approach for mitral valve surgery, especially in patients who require reoperations and in patients with small LA, although we should consider the advantages of SSA versus the risks of post operative arrhythmia and bradycardia.

Adult↗
PubMed1997

The skin injury induced by high energy dose of ultraviolet in hairless descendants of Mexican hairless dogs.

Histopathological changes in the dorsal skin of hairless descendants of Mexican hairless dogs (MHDs) exposed to artificial irradiation with high energy dose (180 kJ/m2) of ultraviolet (UV) rays (UVA + B) were investigated. Macroscopically, erythema and edema were observed in the irradiated skin at 1 day after irradiation (DAI), and blister formation occurred except one dog at 2 DAI. Erythema almost disappeared at 5 DAI, and at 6 DAI, the skin recovered to almost normal state. Light microscopically, sunburn cells were observed at 1 DAI. Then intercellular edema and blister formation in the epidermis and dermal edema were evident at 2 and 3 DAI. At 6 DAI, the skin showed almost normal features except for slight epidermal thickening, but melanin granules, which were distributed in almost the whole length of the epidermis before UV irradiation, were detected only in cells which seemed to be melanocytes except one dog. Dihydroxyphenylalanine (DOPA)-positive melanocytes almost disappeared at 1 and 2 DAI, and at 6 DAI, the number of DOPA-positive melanocytes increased over the level before UV irradiation. The ultrastructural features of melanocytes were characterized by vacuolated cytoplasm, decreased melanosomes, irregular-shaped nuclei and shortened dendrites at 1 DAI, and returned to normal at 6 DAI. These findings of melanocytes reflect the severity of the skin injury and support weak suntan reaction in this case. In conclusion, severe form of UV-induced skin injury seen in humans could be reproduced in hairless descendants of MHDs exposed to high energy dose of artificial UVA + B.

Animals↗
PubMed1997

Ultrastructure of atheromatous lesions experimentally induced in Syrian hamsters of the APA strain.

In order to examine whether diabetes enhances, primary aortic lesions up to atherosclerotic ones, mild primary lesions were induced in aorta of APA hamsters by an administration of vitamin D2 (VD) and/or stop-and-reflow (SR)-operation, a modification of renal artery clamping. At 2 months after the treatment with the combination of VD-administration and SR-operation, atheromatous lesions, characterized by an appearance of many foam cells in the intima, were observed in the abdominal aorta, the site of SR-operation, in streptozotocin (SZ)-induced diabetic APA hamsters. Foam cells in the atheromatous lesions were originated from smooth muscle cells and monocyte/ macrophages. On the other hand, neither VD-administration alone nor SR-operation alone developed atheromatous lesions in SZ-induced diabetic APA hamsters. In conclusion, we succeeded in a rapid induction of atherosclerotic lesions in abdominal aorta of SZ-induced diabetic APA hamsters by the combination of VD-administration and SR-operation.

Animals↗
PubMed1997

5-Azacytidine (5Az) induces apoptosis in PC12 cells: a model for 5Az-induced apoptosis in developing neuronal cells.

Our previous in vivo and in vitro studies showed that 5-azacytidine (5Az), a cytidine analog, induced apoptosis in developing neuronal cells in mice. To develop a system in which the precise molecular mechanism of 5Az-induced apoptosis in developing neuronal cells could be elucidated, we carried out the present study with PC12 cells. These cells are derived from a rat pheochromocytoma and extrude neurites in response to nerve growth factor (NGF). Light microscopy showed dose-dependent pyknotic and karyorrhectic changes in undifferentiated PC12 cells. Although they were less sensitive to 5Az, NGF-treated differentiated cells showed the same changes. Analysis by the TUNEL method (an in situ method for the detection of apoptosis) showed positive signals in the pyknotic and fragmented nuclei of these cells. Transmission electron microscopy revealed margination, segmentation, and condensation of nuclear chromatin, cell body shrinkage, and cytoplasmic vacuolization. Scanning electron microscopy demonstrated bleb formation on the cell surface. These pathomorphological changes are typical of apoptosis. 5Az seemed to affect cells that were in the proliferative stage; when the cells were terminally differentiated, their sensitivity to 5Az appeared to decline. PC12 cells could be used as a pathomorphological and biochemical model for studies of 5Az-induced neuronal cell apoptosis at the molecular and genetic level.

Animals↗
PubMed1997

New reconstructive procedure for brachial plexus injury.

The double free-muscle transfer technique has restored prehension in patients following complete avulsion of the brachial plexus. This achievement was almost inconceivable as recently as several years ago and has now given new hope for these patients to be able to use their otherwise useless limbs.

Adult↗
PubMed1997

Prolonged oval cell proliferation with Ito cell activation and extracellular matrix accumulation in galactosamine-induced acute hepatitis in mini rats.

Histopathological and immunohistochemical studies were carried out on D-galactosamine (GalNAc)-induced acute hepatitis in rats of the JCI: Wistar TgN (ARGHGEN) 1 Nts strain (Mini rats), in which expression of the growth hormone gene is suppressed by an antisense transgene. Hepatitis characterized by hepatocellular acidophilic necrosis with inflammatory cell infiltration was most prominent at 2 days after GalNAc (1000 mg/kg)-injection, when proliferation of Ito cells and deposition of fibronectin and laminin were found along the sinusoidal linings. At 72 hours after GalNAc-injection, Ito cell proliferation with deposition of laminin and fibronectin became more prominent, and marked proliferation of small epithelial cells was observed in the periportal area. At 7 days after GalNAc-injection, quite a number of alpha-smooth muscle actin-positive Ito cells, surrounded by abundant fibronectin, laminin and type IV collagen, were still observed in close juxtaposition to rapidly proliferating small epithelial cells. The small epithelial cells were found to be positive for both alpha-fetoprotein and cytokeratin 7 and were therefore considered to be so-called oval cells. The results suggest that there may be some relation between oval cell proliferation, Ito cell activation and extracellular matrix accumulation in GalNAc-induced acute hepatitis in Mini rats.

Acute Disease↗
PubMed1997

[A case of ruptured thoracoabdominal aortic aneurysm with aortitis syndrome--operation with selective cold visceral arteries perfusion].

We report a successful result of treatment for a ruptured thoracoabdominal aortic aneurysm with aortitis syndrome. A 43-year-old male suffered sudden low back pain, that was diagnosed as a ruptured thoracoabdominal aortic aneurysm based on abdominal computed tomography. Preoperative angiography revealed a thoracoabdominal aortic aneurysm with occlusion of the superior mesenteric artery, and well developed Riolan's archade. The aneurysm was replaced by a prosthetic graft with partial femoro-femoral bypass in conjunction with selective cold perfusion for the visceral arteries. Total extracorporeal circulation time, and aortic clamptime, was 187 minutes and 132 minutes, respectively. The postoperative courses of liver and renal function were excellent. The patient recovered from surgery uneventfully. It was suggested that selective cold visceral perfusion was effective for prevention of renal and liver dysfunction associated with a ruptured thoracoabdominal aneurysm.

Adult↗
PubMed1997

Expression of natriuretic peptide system during embryonic stem cell vasculogenesis.

The natriuretic peptide family consists of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). We have elucidated that CNP is synthesized by endothelial cells. We have also shown that CNP secretion is potently suppressed by vascular endothelial growth factor (VEGF). In the present study, we examined the developmental gene expression of the natriuretic peptide system with the expression of VEGF and endothelial cell-specific receptor tyrosine kinases (RTKs), which expression is necessary for vasculogenesis, using embryoid bodies (EB) as an in vitro model for vascular development. When mouse embryonic stem (ES) cells were cultured in suspension culture, ES cells spontaneously differentiated into EB on day 4 and then into cystic EB (day 10). The VEGF gene transcript was detected early, on day 4. The expression of Flk-1, and flt-1 (the two VEGF receptors) and also of tie-2, which is crucial for blood island formation, was detected as early as day 4, and also on days 8 and 21. In contrast, the expression of flt-4, the receptor for VEGF-C, and tie-1, was first detected on day 21. Along with the developmental expression of these markers of differentiation for endothelial cells, the gene expression of CNP and its specific receptor, ANP-B receptor, was detected on days 4, 8, and 21. In contrast, the gene expression of BNP, which acts as a cardiac hormone, and the gene expression of the ANP-A receptor, which is specific to ANP and BNP, was first detected on days 8 and 21, respectively. These results indicate the distinct role of CNP in the natriuretic peptide family and the close linkage of CNP expression and endothelial cell differentiation, suggesting a possible role of CNP in vasculogenesis.

Animals↗
PubMed1996

Nerve regeneration and origin of Schwann cells in peripheral nerve allografts in immunologically pretreated rats.

For peripheral nerve allografts, the conditions for successful nerve regeneration and the possibility of transplanting Schwann cells were examined using a model of pretreated rats. Incomplete immunosuppression was achieved in recipient rats with donor red blood cell infusions given before allogeneic nerve grafting (RBC group). The origin of Schwann cells in the grafts was assessed by immunohistochemical staining from 1 week to 12 weeks after transplantation. In the RBC group, the replacement of donor Schwann cells by recipient cells was detected at 3-8 weeks, with the graft being filled with many of these cells at all times, and successful nerve regeneration was seen after 12 weeks on morphometric and electrophysiologic evaluations. In peripheral nerve allografts, pretreatment with donor-specific blood transfusion did not induce significant immunosuppression compared with allotransplantations of some tissues and organs. Clinically, if the state of immunosuppression can be controlled by RBC transfusion, it is possible that donor tissues may be replaced by recipient tissues and that nerves will regenerate successfully.

Animals↗
PubMed1996

Archaebacterial lipid models: stable liposomes from 1-alky1-2-phytanyl-sn-glycero-3-phosphocholines.

1-Alky1-2-phytanyl-sn-glycero-3-phosphocholines (HPhyPC: alkyl = n-C16H33; EPhyPC: alkyl = n-C20H41), which are artificial chimeric lipids between archaebacterial and ordinary glycerolipids, are prepared. Upon sonication in aqueous media, the lipids gave rise to stable unilamellar liposomes having diameter of 200-1,000 A and gel-to-liquid crystalline phase transition temperature of -11.1 degrees C (EPhyPC) and -10.8 degrees C (HPhyPC). The vesicles were thermally stable (to about 70 degrees C) and retained efficiently 5(6)-carboxyfluorescein and sodium chloride in the aqueous interior. Physicochemical properties of their membranes were discussed in comparison with those of the membranes made of an archaebacterial model lipid, 1,2-diphytanyl-sn-glycero-3-phosphocholine.

Archaea↗
PubMed1996

The limit of low speed peripheral nerve elongation; neurological and circulatory aspects.

We studied peripheral nerve elongation of rabbit sciatic nerves. External fixators developed in our department were applied to 32 rabbit femurs in vivo. The rabbits underwent osteotomy of the femur and were divided into two groups subjected to different sciatic nerve elongation speeds: group I (0.45 mm/day) and group II (1.35 mm/day). The sciatic nerves were elongated 1.5, 3.0, 4.5, 6.0 and 7.0 cm by the external fixators, and the corresponding actual percentage of elongation of the nerves were 8, 16, 24, 30 and 40%. After elongation, nerve electrophysiology, nerve blood flow and pathology were studied. Forty percent elongation decreased nerve blood flow to 69 +/- 5.1% of contralateral controls in group I and to 20 +/- 4.8% in group II. Although no decrease in motor conduction velocity (MCV) was observed at any elongation distance, compound muscle action potential (CMAP) amplitude gradually decreased with increasing elongation. In group I, after 40% elongation, specimens showed the following pathologic changes: thinning of myelin sheath, atrophy and detachment of the axon from the myelin sheath. Furthermore, in group II, 40% elongation induced disorganization of the myelin sheath and Wallerian degeneration. Consequently 40% elongation was regarded as critical at speeds of both 0.45 and 1.35 mm/day.

Action Potentials↗