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Biomedical subjects

N Sakai

Publications and source records attributed to N Sakai.

At least 361 records · Page 20Linked to original sources
PubMed1996

Malignant fibrous histiocytoma of the esophagus.

A 78-year-old man presented with an esophageal polyp that was confirmed by immunohistochemistry and electron microscopy to be malignant fibrous histiocytoma. The tumor was comprised of a proliferation of spindle-shaped cells admixed with bizarre giant cells. These tumor cells were immunoreactive for smooth muscle actin, vimentin, alpha-1-anti-chymotrypsin and CD68. Electron microscopic examination revealed the myofibroblastic and histiocytic features of the tumor cells. No elements of epithelial or myogenic differentiation were found in the tumor. Malignant fibrous histiocytoma of the esophagus is extremely rare, with 10 cases being documented so far in the literature. The differential diagnosis of pleomorphic tumors of the esophagus is discussed.

Aged↗
PubMed1996

Surgical results of tympanoplasty with hokudai-shaped partial and total ossicular replacement prostheses.

The surgical results of tympanoplasty using a ceramic partial ossicular replacement prosthesis (PORP) or a ceramic total ossicular replacement prosthesis (TORP) were analyzed. The present study included 25 ears in 22 patients who underwent tympanoplasty between December 1986 and September 1994 and were followed up for more than 6 months postoperatively. Because the ceramic prosthesis was extruded from 2 of the 25 ears, the surgical results in the other 23 ears were analyzed, Surgical results were assessed according to a criterion that permits comparison with data from around the world. The criterion considers a postoperative airbone gap within 20 dB as a success. According to this criterion, the success rate was 90.9% for PORP, 50.0% for TORP, and 69.6% in total. These results are comparable with those found at other centers.

Adolescent↗
PubMed1996

Thyroplasty type I with ceramic shim.

To prevent side effects from a silicone shim in Isshiki thyroplasty type I, we used a ceramic shim in 10 patients with unilateral recurrent laryngeal nerve paralysis. No published reports have described the use of ceramic in this type of surgery. According to the degree of glottic insufficiency, ceramic shims of various heights were inserted into the fenestration made in the thyroid ala. All patients experienced subjective improvement of voice postoperatively. Laryngoscopies in most cases showed that glottic insufficiency improved postoperatively. In the postoperative examination, the maximum phonation time improved an average of 3.7 s, and the mean flow rate improved an average of 331 ml/s. We have analyzed the relationship of these improvements to the degree of glottic insufficiency and have compared our results with those of other investigators.

Adult↗
PubMed1996

An experience of the usage of electrical tinnitus suppressor.

An electrical tinnitus suppressor based on the use of an extracochlear stimulator has been developed at Hokkaido University, Sapporo, Japan, and was implanted in 2 male and 2 female patients. Tinnitus improved in all patients because the auditory nerve was able to be stimulated at home whenever patients wanted treatment. Additional benefits reported after electrical stimulation of the cochlea included sound sleep, relaxation in all cases, and improved hearing acuity in Cases 1, 2, and 4. Minimal temporary complications, including habituation and ear drum perforation, were observed.

Adult↗
PubMed1996

Identification of novel missense mutations (Phe310Leu and Gly439Arg) in a neonatal case of hypophosphatasia.

Hypophosphatasia is associated with a defect of the tissue-non-specific alkaline phosphatase gene. We performed a mutational analysis in a surviving patient diagnosed at birth as having hypophosphatasia, on the basis of a low level of serum alkaline phosphatase (ALP) activity and characteristic radiographical findings. She had two sisters, one of whom died of respiratory failure complicated by perinatal hypophosphatasia; the other seemed healthy, with a relatively low activity level of ALP. The patient's parents also had low ALP activity. Sequence analysis of the tissue-nonspecific alkaline phosphatase gene was performed, using genomic DNA and total RNA from the skin fibroblasts of the patient and the peripheral mononuclear cells of her parents. The conversion of Phe to Leu at codon 310 (F310L) and Gly to Arg at 439 (G439R) were identified in the patient. Interestingly, the reconstructive experiments demonstrated that the F310L mutant exhibited an ALP activity level 65% of the normal level, whereas the mutant G439R had no activity. Moreover, the digestion by StuI, after a PCR using complementary DNA extracted from fibroblasts of the patient and lymphocytes of her father, revealed a relatively low messenger RNA level of F310L. These findings suggest that the neonatal case of hypophosphatasia was associated with compound mutations, one of which caused the loss of ALP activity and the other of which caused a slight reduction of the ALP activity, with a relatively low level of messenger RNA.

Adult↗
PubMed1996

Electrophysiological and pharmacological characteristics of ionotropic glutamate receptors in medial vestibular nucleus neurons: a whole cell patch clamp study in acutely dissociated neurons.

A patch clamp study was performed to determine which subtype of ionotropic glutamate receptors is involved in the glutamate-induced excitation of the medial vestibular nucleus (MVN) neurons. Whole cell recording was performed on MVN neurons that were acutely dissociated by enzymatic and mechanical treatments. Application of glutamate at a concentration of 100 microM produced a current with a reversal potential of approximately 0 mV. The glutamate-induced current was completely blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM), a non-N-methyl-D-aspartate (NMDA)-receptor antagonist. Application of alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) and kainic acid (KA), non-NMDA-receptor agonists, at concentrations of 30 and 100 microM produced a concentration-dependent depolarization concomitantly with an increase in firing rates during current clamp recording. During voltage clamp recording, glutamate, AMPA and KA elicited a concentration-dependent current with an equilibrium potential of approximately 0 mV. To clarify whether NMDA receptors are present in MVN neurons, the effects of glycine on the glutamate- and NMDA-induced current were examined. Two types of NMDA receptor-mediated current (types 1 and 2) were obtained in terms of the difference in sensitivity to both magnesium ion and MK-801, which act on the NMDA-receptor channel. In the type 1 neurons, the NMDA-induced current was not apparently blocked by magnesium ion or MK-801, although a larger current was obtained in the absence of magnesium ion. In the type 2 neurons, marked blockade of the NMDA-induced current was seen in the presence of magnesium ion and MK-801, as previously reported in other neurons of the central nervous system. These findings indicate the presence of both non-NMDA and NMDA receptors, which are involved in primary afferent transmission, in the MVN neuron, and two distinct types of NMDA receptors.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1996

Late onset diabetes mellitus in patients with hereditary aceruloplasminemia.

Aceruloplasminemia is a systemic degenerative disorder characterized by mutations in the ceruloplasmin gene, the absence of serum ceruloplasmin, and iron accumulation in the brain, liver, and other tissues. Iron is an important catalyst of oxyradical-mediated cellular and tissue injury, and beta-cells in the pancreatic islets are susceptible to the cytotoxic effects of oxidative stress. We report three patients with aceruloplasminemia who have late-onset diabetes mellitus (DM) and impaired glucose tolerance (IGT) as well as neurologic symptoms. Their basal lipid peroxide levels, measured as thiobarbituric acid-reactive products, in plasma samples were three times the values for the controls. This increased susceptibility to lipid peroxidation in patients with aceruloplasminemia suggests that free-radical-mediated tissue injury plays a role in the occurrence of DM and IGT.

Brain↗
PubMed1996

Cervical discitis associated with spinal epidural abscess caused by methicillin-resistant staphylococcus aureus.

A 53-year-old male developed fever, nuchalgia, shoulder pain, and sore throat after a partial sigmoidectomy. He suffered sudden onset of quadriplegia about 5 days later. Magnetic resonance (MR) imaging indicated the characteristic appearance of C5-6 intervertebral disc herniation. However, anterior discectomy showed that he had cervical discitis associated with spinal epidural abscess. Continuous pus drainage from the abscess and vigorous antibiotic therapy were undertaken after surgery. He improved and could walk with assistance. MR imaging with gadolinium can be useful in diagnosing pyogenic spinal infection (epidural abscess, osteomyelitis, and discitis), but care should be taken in MR image interpretation since spinal epidural abscess associated with discitis may mimic disc herniation. Axial MR images are important to distinguish this rare disease from other cervical disorders.

Abscess↗
PubMed1996

Pain reduction after anteromedial displacement of the tibial tuberosity: 5-year follow-up in 21 knees with patellofomoral arthrosis.

We performed anteromedial displacement of the tibial tuberosity in 21 knees of 16 patients having patellofemoral arthrosis with lateral subluxation. The mean age of the patients was 53 (47-65) years and they were followed for 5(2-13) years. Preoperatively, all knees were painful on descending or ascending stairs; pain was relieved after operation in 20. Retropatellar crepitations disappeared in 2 of 20 knees, but retropatellar pain when squeezing the patella against the femur disappeared in 16 of 17 knees. Patellar subluxation diminished in all knees.

Aged↗
PubMed1996

Molecular disorders of cholesteryl ester transfer protein.

Plasma cholesteryl ester transfer protein (CETP) facilitates the transfer of cholesteryl ester (CE) from HDL to apolipoprotein B-containing lipoproteins and therefore is a key protein in the reverse cholesterol transport system. The importance of plasma CETP in lipoprotein metabolism has been highlighted by the discovery of CETP-deficient subjects with a marked hyper-HDL-cholesterolemia. The deficiency of CETP causes various abnormalities in the concentration, composition, and functions of high density and low density lipoproteins. The current review will focus on some of the recent knowledge on CETP with special reference to the biochemical and molecular biological aspects of CETP. Furthermore, detailed information will be presented regarding the lipoprotein abnormalities and molecular basis of CETP deficiency.

Animals↗
PubMed1996

A new isopatulin derivative pintulin produced by Penicillium vulpinum F-4148 taxonomy, isolation, physico-chemical properties, structure and biological properties.

During our screening program of natural products from fungal metabolites for drugs effective against tumor cell lines, we discovered a new isopatulin derivative, pintulin, from the fermentation broth of Penicillium vulpinum F-4148. Pintulin shows weak activity against tumor cell lines, compared to that of adriamycin.

Antibiotics, Antineoplastic↗
PubMed1996

Surgical Method for Implanted Tinnitus Suppressor.

A surgical method of fully internal tinnitus suppressor is presented. The surgical approach for the placement of the electrode is very simple and causes less injury to the cochlea. This surgical approach is quite similar to the exploratory tympanotomy. The unit is located at the seat which is drilled in the mastoid bone just behind the external ear canal. The stimulating electrode is introduced to the middle ear beneath the skin of the ear canal on the posterior bony wall. The tip of the electrode located on the promontory is secured by the fascia The primary coil is contained in the Behind-the-Ear case.

Journal Article↗
PubMed1996

Increased Parasympathetic Nerve Tone in Tinnitus Patients Following Electrical Promontory Stimulation.

Cutaneous digital blood flow (CDBF) during electrical promontory stimulation was measured by laser Doppler flowmetry in 46 tinnitus patients. In patients with tinnitus suppression. CDBF was increased. In contrast, patients in whom treatment did not suppress tinnitus experienced no change in digital blood flow. The cutaneous digital blood flow of patients who experienced slight relief did not differ significantly from patients who experienced no relief. The ratio of CDBF before and after treatment did not correlate with patient age, audiogram pattern. Our results suggest that relief of tinnitus was closely related to increased parasympathetic nerve tone.

Journal Article↗
PubMed1996

Improved Selective Attention and Word Perception in Tinnitus Patients Treated with Electrical Stimulation.

Grammatically correct but nonsense twenty 4-segment sentences mixed with multiple talk recorded on CD were delivered to ears tested in 47 tinnitus patients at a comfortable level via a headphone. The signal-to-noise ratios were 0dB, 5dB and 10dBSPL. Patients were requested to repeat what they heard before and after electrical treatment. A sinusoidal wave of 10kHz at the intensity of about 200mA was delivered to ears for 30 minutes by using a plate electrode for ECG at the tragus or a stimulating Pt-Ir electrode on the middle ear. Alternatively, 0.5mA DC was delivered to patients using a iontophoretic instrument. Improved word perception under noises was observed in most patients with tinnitus relief following electrical stimulation of the ear, demonstrating that electrical stimulation improved auditory selective attention. There may be a relationship between tinnitus relief and improved selective attention. It may be electrical stimulation of the ears that produced improved selective attention, inducing tinnitus relief and improved word perception according to our previous reports.

Journal Article↗
PubMed1996

Stimulation of megakaryocytopoiesis in mice by human modified C-reactive protein (mCRP)

The prototypic human acute phase reactant, C-reactive protein (CRP), and a structurally modified form of CRP (mCRP) were studied as agents which could stimulate thrombopoiesis in both in vitro and in vivo mouse models. mCRP, but not the widely studied (native) pentameric form of CRP, demonstrated significant megakaryocyte colony-stimulating activity. This activity was measured in plasma clot cultures incubated with pokeweed mitogen-stimulated spleen cell conditioned medium (PWM-SCM). mCRP increased the number of mouse megakaryocyte colonies in a dose-dependent manner. While significantly more colonies were observed in mCRP-treated cultures compared to controls, the kinetics of megakaryocyte growth and maturation were similar to those measured in cultures stimulated with PWM-SCM lacking mCRP. A low level of megakaryocyte growth-promoting activity was noted when mCRP was added to plasma clot cultures not incubated with spleen cell conditioned medium. However, the most striking activity of mCRP was in potentiating stimulated megakaryocyte colony formation (i.e., as a Meg-POT factor). In in vivo experiments, mCRP injected subcutaneously into normal mice resulted in significant increases in blood platelet numbers compared to control mice receiving sham injections. These results suggest that a modified form of CRP has thrombopoietic activity in both in vitro and in vivo mouse models, Therefore, one important biological role for CRP during an acute-phase response might be to contribute, after a structural modification, to the hematopoietic regulation of blood platelets.

Acute-Phase Reaction↗
PubMed1996

Chest flow during the initial inspiratory phase (V0.1) in pulmonary diseased patients.

We measured the chest flow 0.1 s after the onset of the inspiratory phase (V0.1) in patients with chronic pulmonary emphysema (CPE: n = 5), interstitial pneumonitis (IP: n = 5) and normal subjects (Nor: n = 5). The subjects sat in a body box and breathed air from outside of the body box. V0.1 was measured during rest and during maximal breathing (V0.1-rest, V0.1-max) and then these results were compared with P0.1 (P0.1 rest, P0.1-max) values. V0.1-rest was not significantly different between the three groups (Nor: 0.25 +/- 0.10, CPE: 0.27 +/- 0.06, IP: 0.26 +/- 0.06, l/s), whereas the P0.1-rest in IP patients was significantly greater than in normal subjects (Nor: 1.98 +/- 0.61, CPE: 3.00 +/- 0.80, IP: 3.60 +/- 0.68 hPa; P < 0.05 compared with normal). The V0.1-max in CPE and IP patients was significantly lower than in normal subjects (Nor: 3.66 +/- 1.16, CPE: 0.82 +/- 0.25, IP: 1.02 +/- 0.21 l/s, P < 0.05 compared with normal subjects (Nor: 3.66 +/- 1.16, CPE: 0.82 +/- 0.25, IP: 1.02 +/- 0.21 l/s, P < 0.05 compared with normal), whereas P0.1-max in IP patients was not significantly different with in normal subjects (Nor: 33.2 +/- 10.2, CPE: 9.8 +/- 3.7, IP: 19.5 +/- 3.4 hPa, P < 0.05 compared with normal, P < 0.05 compared with CPE). A simulation of the influence of the mechanical properties of the respiratory system on V0.1 and P0.1 using the Runge-Kutta method suggested that V0.1 was negatively affected by airway resistance but positively affected by chest wall and lung compliance. In contrast, the influence of respiratory mechanics on P0.1 was much less than on the V0.1, except for highly decreased lung compliance. In CPE patients, it was suspected that mechanical disorders might not simply be the determining factors of V0.1-max, but that limitations of the neuro-muscular drive due to chest wall deformity may also play a definitive role in the smaller V0.1-max. In contrast, it may be inferred that IP patients had to exert greater inspiratory effort as compared with the other two groups in order to maintain a similar V0.1-rest because of the increased airway resistance and decreased tissue compliance; thus these abnormal mechanical properties suppress the increase in the V0.1-max. It may be concluded that V0.1 is a good index of chest wall acceleration, which is determined by both the neuro-muscular drive and the mechanics of the respiratory system.

Aged↗