Biomedical subjects
F Sakai
Publications and source records attributed to F Sakai.
The homozygous C677T mutation in the methylenetetrahydrofolate reductase gene is a genetic risk factor for migraine.
Increased homocysteine levels are associated with various pathological conditions in humans, including stroke and cardiovascular disorders. Homocysteine acts as an excitatory amino acid in vivo and may influence the threshold of migraine headache. Frosst et al. [1995] reported an association between the homozygous C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene and serum homocysteine levels. This study was designed to determine the prevalence of the MTHFR mutation in Japanese patients with migraine and tension-type headache (TH). Seventy-four patients with migraine headaches (22 with aura and 52 without aura), 47 with THs, and 261 normal controls were recruited. Genotyping of MTHFR C677T polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism. We detected that the incidence of the homozygous transition (T/T) in migraine sufferers (20.3%) was significantly higher than that in controls (9.6%). Moreover, the frequency of the T/T genotype in individuals with migraine headaches with aura was remarkably high (40.9%). The MTHFR T allele was more frequent in the migraine group than in the control group. Our results support the conclusion that the MTHFR gene, causing mild hyperhomocysteinemia may be a genetic risk factor for migraine. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:762-764, 2000.
LiV2O4 spinel as a heavy-mass fermi liquid: anomalous transport and role of geometrical frustration
Transport and specific heat measurements on hydrothermally grown single crystals reveal the formation of a heavy-mass Fermi liquid in the LiV2O4 spinel, below a coherence temperature of T* = 20-30 K. A few observations which illustrate the uniqueness of this spinel are discussed in connection with the origin of the heavy mass, such as the anomalous absence of resistivity saturation above T* and the close proximity to a spin glass phase where the influence of the magnetic frustration is evident.
NXP-1, a human protein related to Rad21/Scc1/Mcd1, is a component of the nuclear matrix.
Nuclear matrix is a complex intranuclear network supposed to be involved in the various nuclear functions. In order to identify the nuclear matrix proteins, we isolated a cDNA clone from a human placenta cDNA library. This clone was partially represented a known cDNA clone HA1237. HA1237 encoded a 631-amino-acid peptide, which we designated NXP-1. NXP-1 was related to yeast Rad21/Scc1/Mcd1, Xenopus XRAD21, and mouse PW29, and identical with HR21spA isolated from a human testis cDNA library. We developed a polyclonal antibody to the purified NXP-1 bacterially expressed as a fusion protein with GST. Western blot analysis with anti-NXP-1 polyclonal antibody showed nuclear matrix localization of NXP-1 in HeLa cells. Indirect immunofluorescence staining also showed nuclear and nuclear matrix localization of the NXP-1. Results of in vitro binding assays employing nuclear matrix preparations indicated that the N-terminal region (16-128 amino acid) of NXP-1 has an important role in nuclear matrix distribution.
Midazolam and ketamine inhibit glutamate release via a cloned human brain glutamate transporter.
PURPOSE: In cerebral ischemia/anoxia, the glutamate transporter runs in reverse and releases glutamate into the extracellular space, causing irreversible neuronal damage. Intravenous anesthetics attenuate overall glutamate release and prevent neuronal injury during anoxia/ischemia, but their effect on the glutamate transporter is variable. METHODS: A human glial glutamate transporter (hGLT-I) cDNA was isolated by screening a human cerebral cortical library. Cloned cDNA was transfected in Chinese hamster ovary cells. The effect of the intravenous anesthetics midazolam (0.3 to 30 microM), ketamine (10 to 100 microM), thiopental (30 to 300 microM), and propofol (3 to 30 microM) on reversed uptake of L-glutamate via hGLT-I was examined by whole-cell patch-clamp. RESULTS: Midazolam at a concentration 3 microM reduced outward currents arising from reversed L-glutamate uptake via hGLT-I in a concentration-dependent manner. While, ketamine at 100 microM attenuated the same outward currents, to 53.3+/-11.4% of those seen in controls without anesthetics (P<0.05, n=5). In contrast, neither thiopental nor propofol showed effects on outward currents mediated by reversed operation of hGLT-I. CONCLUSIONS: These results suggest that midazolam and ketamine, but not thiopental and propofol, have a capacity to inhibit glutamate release via GLT- I directly.
Evidence that endo-1,4-beta-glucanases act on cellulose in suspension-cultured poplar cells.
Suspension-cultured poplar (Populus alba) cells produce two distinct endo-1,4-beta-glucanases, one of which is released in the extracellular culture medium and the other localized in their walls. Two cDNA clones, PopCel1 and PopCel2, isolated from a poplar cDNA library, encode the extracellular and the wall-bound endo-1, 4-beta-glucanases, respectively, based upon deduced amino acid sequences. The products of these two genes contained domains conserved in endo-1,4-beta-glucanase (family 9) and showed 91.5% amino acid identity. The levels of both PopCel1 and PopCel2 mRNAs increased during the lag phase of growth and decreased rapidly during the linear phase. After the levels had decreased, they were again increased by addition of sucrose to the culture medium and further enhanced by the addition of 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of sucrose. The accumulation of the mRNAs was correlated with the solubilization of cello-oligosaccharides. Cello-oligosaccharides and xyloglucan were also solubilized from the wall preparations of poplar cells incubated with enzyme preparations from the extracellular culture medium and walls. An antibody against both PopCel proteins reduced the production of cello-oligosaccharides by the extracellular enzyme by 90% and that by the wall-bound enzyme by 55%, and also prevented xyloglucan solubilization. The results show that the accumulation of poplar endo-1,4-beta-glucanases is regulated indirectly by auxin in the presence of sucrose and can act on cellulose in suspension-cultured poplar cells.
Possible mechanisms of glyceryl-trinitrate-induced immediate headache in patients with chronic tension-type headache.
Nitric oxide (NO) plays an important role in the pathophysiology of primary headaches including chronic tension-type headache (CTTH). Thus, a NO synthase inhibitor reduces headache and muscle hardness while the NO donor glyceryl trinitrate (GTN) causes more headache in patients than in healthy controls. Sensitization of myofascial pain pathways is important in CTTH, and the aim of the present study was to investigate if such mechanisms may also explain GTN-induced immediate headache in patients with CTTH. In a randomized, double-blind, crossover study 16 patients with CTTH and 16 healthy subjects received intravenous infusion of GTN (0.5 microg/kg per min for 20 min) or placebo on two headache-free days separated by at least 1 week. Muscle hardness, myofascial tenderness, mechanical and heat pain thresholds were measured at baseline and at 60 min and 120 min after start of infusion. In patients, GTN infusion resulted in a biphasic response with immediate headache and more pronounced delayed headache. A similar but less pronounced response was seen in controls. There was no difference between GTN and placebo regarding muscle hardness, myofascial tenderness or pressure and heat pain thresholds in either patients or controls (P>0.05). The unchanged sensitivity of pericranial myofascial pain pathways indicates that peripheral and central sensitization is not involved in the mechanisms of GTN-induced immediate headache.
Safety and tolerability of rizatriptan.
Explore the source record for details and available documents.
Effects of mild versus deep hypothermia on a cloned human brain glutamate transporter (GLT-1) expressed in Chinese hamster ovary cells.
Glutamate transporters, widely distributed in the brain and spinal cord, maintain extracellular glutamate concentrations below neurotoxic levels. In cerebral ischemia/anoxia, the glutamate transporter runs in reverse and releases glutamate into the extracellular space, causing irreversible neuronal damage. Although hypothermia reduces the elevation of extracellular glutamate concentration during cerebral ischemia/anoxia, little is known about the effect of hypothermia on the glutamate transporter. A human glial glutamate transporter (hGLT-1) cDNA was isolated by screening a human cerebral cortical library, and cloned cDNA was stably transfected in Chinese hamster ovary (CHO) cells. Effects of deep hypothermia (22 to 23 degrees C) on uptake and release of L-glutamate via hGLT-1 were investigated by whole-cell patch-clamp. The control study was performed at 34 to 35 degrees C. The hGLT-1 transporter had the capacity to take up extracellular L-glutamate under essentially physiological ionic conditions, whereas this transporter promoted release of L-glutamate under a nonphysiological condition mimicking complete ischemia. Deep hypothermia decreased a) uptake and b) release of L-glutamate via hGLT-1 to a) 4.8+/-4.8% (P < .01, n = 7) and b) 19.0+/-4.5% (P < .01, n = 15) of control values, respectively. The results suggest that deep hypothermia is a potent inhibitor of glutamate uptake by intact glial cells as well as glutamate release from glial cells under certain pathophysiological circumstances. The balance between these antagonistic effects of hypothermia may attenuate the elevation of the extracellular glutamate concentration during ischemia/anoxia.
A homologue of EGL1 encoding endo-1,4-beta-glucanase in elongating pea stems.
A gene (EGL2) encoding an endo-1,4-beta-glucanase in peas has been cloned as a homologue of EGL1. EGL2 encodes a polypeptide of 506 amino acids, including a 24-mer putative signal polypeptide. The gene product contains a domain conserved in endo-1,4-beta-glucanase (family 9) showing 60% amino acid identity to EGL1. EGL2 mRNA was accumulated only in the elongating regions of pea stems, although EGL1 mRNA was abundant in both elongating and non-elongating tissues. However, the level of EGL2 mRNA was not increased by the treatment with sucrose and auxin in pea segments. These results suggest that the expression of EGL2 either requires the presence of other factors related to the auxin effect or occurs independent of auxin in the elongating pea stems.
KL-6 as a novel serum marker for interstitial pneumonia associated with collagen diseases.
OBJECTIVE: To investigate the diagnostic value of the serum concentrations of KL-6, a mucinous glycoprotein expressed on type II pneumocytes, for interstitial pneumonia (IP) in various collagen diseases. METHODS: Serum KL-6 levels were measured by ELISA. RESULTS: The mean values and the positive rates of serum KL-6 levels for patients with rheumatoid arthritis, systemic sclerosis, or polymyositis/dermatomyositis with IP were significantly higher than those without IP. Sensitivity, specificity, positive and negative predictive values of serum KL-6 level for IP associated with collagen diseases were 60.7, 98.9, 97.4, and 77.1%, respectively. The mean serum KL-6 level of patients with active IP was significantly (p = 0.0001) higher than that of patients with inactive IP. Serum KL-6 levels increased with the deterioration of IP, while the successful treatment of IP resulted in a significant decrease of these levels. CONCLUSION: Serum KL-6 concentration levels are a useful marker for diagnosis and evaluation of the disease activity of IP associated with collagen diseases.
[A questionnaire survey of surgical lung biopsy in patients with diffuse lung diseases].
A nationwide questionnaire survey was conducted to investigate the indications, diagnostic yield, complications, outcome, and benefit of surgical lung biopsy for diffuse lung diseases. Surgical lung biopsies were performed in 410 patients at 132 institutes in 1998, 94% of them as video-assisted thoracoscopic surgery (VATS). Interstitial lung diseases of unknown etiology formed the largest diagnostic group, and consisted of 194 patients. The clinical diagnosis prior to lung biopsy was inconsistent with the final diagnosis in 32.8%. Complications were seen in 32 patients, and mortality was 1.2%. Acute exacerbation of the underlying disease was seen in 9 patients, four of whom died. Patients with nonspecific interstitial pneumonia and even usual interstitial pneumonia who were treated following biopsy showed better outcomes than those untreated. The physician in charge judged that 82.2% of the patients received clinical benefits from the biopsy procedure. We concluded that VATS lung biopsies are indicated in more cases to confirm diagnoses and as a reference for treatments in patients with diffuse lung disease.
[Diagnosis and recent treatment of migraine].
This lecture discusses prevalence, diagnosis and recent treatment of migraine in Japan. It particularly emphasizes the necessity for better medical delivery to patients with migraine. The nationwide population study showed that migraine is just as common a disorder as in other countries. The overall prevalence of migraine was 8.4% among people aged 15 years or older. Severity of migraine was similar to previous reports from other countries. Migraine sufferers in Japan do not consult a physician regularly for the problem. Yet, approximately 70% of the migraine sufferers complained that migraine headache disturbed their daily activity to a major degree. With many migraine sufferers who deserve medical care, the necessity for improved medical care is beginning to be widely recognized. New medicine such as sumatriptan is on market now and its proper clinical use is important.
[Nervous system dysfunctions associated wtih systemic diseases: discussion].
Explore the source record for details and available documents.
Enhancement of cellulose production by expression of sucrose synthase in Acetobacter xylinum.
Higher plants efficiently conserve energy ATP in cellulose biosynthesis by expression of sucrose synthase, in which the high free energy between glucose and fructose in sucrose can be conserved and used for the synthesis of UDP-glucose. A mixture of sucrose synthase and bacterial cellulose synthase proceeded to form UDP-glucose from sucrose plus UDP and to synthesize 1,4-beta-glucan from the sugar nucleotide. The mutant sucrose synthase, which mimics phosphorylated sucrose synthase, enhanced the reaction efficiency (Vmax/Km) on 1,4-beta-glucan synthesis, in which the incorporation of glucose from sucrose was increased at low concentrations of UDP. Because UDP formed after glucosyl transfer can be directly recycled with sucrose synthase, UDP-glucose formed appears to show high turnover with cellulose synthase in the coupled reaction. The expression of sucrose synthase in Acetobacter xylinum not only changed sucrose metabolism but also enhanced cellulose production, in which UDP-glucose was efficiently formed from sucrose. Although the level of UDP-glucose in the transformant with mutant sucrose synthase cDNA was only 1.6-fold higher than that in plasmid-free cells, the level of UDP was markedly decreased in the transformant. The results show that sucrose synthase serves to channel carbon directly from sucrose to cellulose and recycles UDP, which prevents UDP build-up in cellulose biosynthesis.
Muscle hardness in patients with chronic tension-type headache: relation to actual headache state.
It has recently been reported that the pericranial muscles in patients with chronic tension-type headache are harder, i.e. have a higher consistency, than in controls. The primary aim of the present study was to investigate whether muscle hardness is influenced by the presence or absence of actual headache and whether hardness is correlated to tenderness. The secondary aim was to compare muscle hardness between patients and healthy controls. Hardness of the trapezius muscle was measured with a hardness meter in 20 patients with chronic tension-type headache and in 20 healthy controls. The patients were examined on 2 days, 1 day with headache and 1 day without headache. Pericranial myofascial tenderness was recorded with manual palpation. In addition, muscle hardness was measured in another five patients out-side headache and in 30 healthy controls. The muscle hardness recorded in patients (n = 20) on days with headache, 98 +/- 26 kPa/cm, did not differ significantly from the muscle hardness recorded on days without headache, 100 +/- 21 kPa/cm, (P = 0.62). The muscle hardness was positively correlated to the local tenderness score recorded from the trapezius muscle both on days with headache (R = 0.52, P = 0.02) and on days without headache (R = 0.53, P = 0.02). The total tenderness score (TTS) recorded in patients on days with headache, 23 +/- 10, was significantly higher than the TTS recorded on days without headache, 15 +/- 11, (P = 0.0001). There was a significant difference between the TTS recorded in patients without headache, 15 +/- 11, and in controls, 4 +/- 4, (P = 0.002). The muscle hardness was significantly higher in patients on days without headache (n = 25), 97 +/- 20 kPa/cm, than in controls (n = 30), 87 +/- 16 kPa/cm (P = 0.03). On basis of previous and present results, we suggest that muscle hardness and muscle tenderness are permanently altered in chronic tension-type headache and not only a consequence of actual pain. In addition, the positive correlation between muscle hardness and tenderness supports the common clinical observation that tender muscles are harder than normal muscles.
Expiratory and inspiratory chest computed tomography and pulmonary function tests in cigarette smokers.
This study evaluated small airway dysfunction and emphysematous destruction of lung parenchyma in cigarette smokers, using chest expiratory high-resolution computed tomography (HRCT) and pulmonary function tests (PFT). The degree of emphysematous destruction was classified by visual scoring (VS) and the average HRCT number at full expiration/full inspiration (E/I ratio) calculated in 63 male smokers and 10 male nonsmokers (group A). The Brinkman smoking index (BI), defined as cigarettes x day(-1) x yrs, was estimated. Sixty-three smokers were divided into three groups by PFT: group B1 (n=7), with normal PFT; group B2 (n=21), with diffusing capacity of the lung for carbon monoxide (DL,CO) > or = 80% predicted, forced expiratory volume in one second (FEV1) < 80% pred and/or residual volume (RV) > 120% pred; and group B3 (n=35), with DL,CO < 80% pred, FEV1 < 80% pred and/or RV > 120% pred. Heavy smokers (BI > or = 600) (n=48) showed a significant increase in emphysema by both VS and E/I. E/I was significantly elevated in both group B2 (mean+/-SD 0.95+/-0.05) and B3 (0.96+/-0.06) compared with group B1 (0.89+/-0.03). VS could not differentiate group B2 (3.9+/-5.0) from B1 (1.1+/-1.6). These findings suggest that the expiration/inspiration ratio reflects hyperinflation and airway obstruction, regardless of the functional characteristics of emphysema, in cigarette smokers.
Possible mechanisms of action of nitric oxide synthase inhibitors in chronic tension-type headache.
It has been demonstrated recently that nitric oxide synthase (NOS) inhibition has an analgesic effect in patients with chronic tension-type headache. The aim of the present study was to investigate the influence of the NOS inhibitor, L-N(G) methyl arginine hydrochloride (L-NMMA), on two of the most prominent features of chronic tension-type headache, i.e. increased muscle hardness and increased myofascial tenderness. In a double blind, crossover designed trial, 16 patients with chronic tension-type headache were randomized to receive intravenous infusion of 6 mg/kg L-NMMA or placebo on 2 days separated by at least 1 week. Muscle hardness of the trapezius muscle was measured with a hardness meter. Myofascial tenderness in the pericranial region was evaluated by manual palpation with standardized and validated methodology. All parameters were recorded at baseline and at 60 and 120 min after start of infusion. Compared with baseline, muscle hardness, 107 +/- 17 kPa/cm and tenderness, 18 +/- 11 were significantly reduced at 60 and 120 min to: hardness, 101 +/- 17 kPa/cm and 101 +/- 17 kPa/cm, respectively; tenderness, 15 +/- 11 and 14 +/- 11, respectively, after treatment with L-NMMA (P < 0.05 and P < 0.01, respectively), while there was no significant reduction at any time after treatment with the placebo. Compared with the placebo, the summary score of muscle hardness was significantly reduced (P = 0.04), while tenderness showed a non-significant reduction (P = 0.11) following treatment with L-NMMA. Since increased muscle hardness in patients with chronic tension-type headache may reflect sensitization of second order neurons due to prolonged nociceptive input from myofascial tissues, we suggest that the decrease in muscle hardness following treatment with L-NMMA may be caused by reduction of central sensitization.