Triad stimulation frequency for cortical facilitation in cortical myoclonus.

BACKGROUND: Abnormally enhanced cortical rhythmic activities have been reported in patients with cortical myoclonus. We recently reported a new triad-conditioning transcranial magnetic stimulation (TMS) method to detect the intrinsic rhythms of the primary motor cortex (M1). Triad-conditioning TMS revealed a 40-Hz intrinsic rhythm of M1 in normal subjects. In this investigation, we study the motor cortical facilitation induced by rhythmic triple TMS pulses (triad-conditioning TMS) in patients with cortical myoclonus. METHODS: Subjects were 7 patients with cortical myoclonus (28-74 years old) and 13 healthy volunteers (30-71 years old). Three conditioning stimuli over M1 at the intensity of 110% active motor threshold preceded the test TMS at various interstimulus intervals corresponding to 10-200 Hz. The resulting amplitudes of conditioned motor evoked potentials recorded from the contralateral hand muscle were compared with those evoked by the test stimulus alone. RESULTS: The facilitation at 25 ms (40 Hz) observed in normal subjects was absent in patients with cortical myoclonus. Instead, triad-conditioning TMS induced facilitation at a 40 ms interval (25 Hz) in cortical myoclonus. DISCUSSIONS: This change in the timing of facilitation may be explained by a shift of the most preferential intrinsic rhythm of M1, or by some dysfunction in the interneuronal network in cortical myoclonus.

New neuropeptides containing carboxy-terminal RFamide and their receptor in mammals.

Only a few RFamide peptides have been identified in mammals, although they have been abundantly found in invertebrates. Here we report the identification of a human gene that encodes at least three RFamide-related peptides, hRFRP-1-3. Cells transfected with a seven-transmembrane-domain receptor, OT7T022, specifically respond to synthetic hRFRP-1 and hRFRP-3 but not to hRFRP-2. RFRP and OT7T022 mRNAs are expressed in particular regions of the rat hypothalamus, and intracerebroventricular administration of hRFRP-1 increases prolactin secretion in rats. Our results indicate that a variety of RFamide-related peptides may exist and function in mammals.

Short-interval intracortical inhibition in Parkinson's disease using anterior-posterior directed currents.

Reduced short-interval intracortical inhibition (SICI) is reported in Parkinson's disease (PD) and is considered to reflect abnormal GABAergic inhibitory system of the primary motor cortex in PD. We have recently shown, however, that SICI using anterior-posterior directed currents in the brain was normal in focal dystonia even though that using posterior-anterior currents was abnormal, indicating that the GABAergic system of the primary motor cortex is largely normal in dystonia. Here, we studied SICI in PD to clarify whether the GABAergic system is completely impaired in PD. We used paired-pulse transcranial magnetic stimulation to study SICI at interstimulus intervals of 3 and 4 ms with anterior-posterior or posterior-anterior directed currents in eight PD patients and ten healthy volunteers. The amount of SICI with posterior-anterior directed currents was reduced in PD patients compared with healthy volunteers; in contrast, SICI studied with anterior-posterior directed currents was normal in PD patients. These observations may be due to the difference in I-wave composition generated by the two directed currents and/or the difference in responsible inhibitory interneurons for the inhibition between the two current directions. We suggest that some or a part of inhibitory interneurons are not involved in PD. This discrepancy between SICI using posterior-anterior and anterior-posterior directed currents experiments may provide additional information about the circuits of the motor cortex.

A comparison of the effect on QT interval between thiamylal and propofol during anaesthetic induction*.

SUMMARY: The aim of this study was to determine the effect of thiamylal and propofol on heart rate-corrected QT (QTc) interval during anaesthetic induction. We studied 50 patients undergoing lumbar spine surgery. Patients were administered 3 microgxkg(-1) fentanyl and were randomly allocated to receive 5 mgxkg(-1) thiamylal or 1.5 mgxkg(-1) propofol as an induction agent. Tracheal intubation was performed after vecuronium administration. Heart rate, mean arterial pressure, bispectral index score, and 12-lead electrocardiogram were recorded at the following time points: just before (T1) and 2 min after (T2) fentanyl administration; 2 min after anaesthetic administration (T3); 2.5 min after vecuronium injection (T4); and 2 min after intubation (T5). Thiamylal prolonged (p < 0.0001), but propofol shortened (p < 0.0001), the QTc interval.

Molecular and biological characterization of gtf regulation-associated genes in Streptococcus mutans.

INTRODUCTION: Surface protein antigen (PAc) and glucosyltransferases (GTF) are major adhesive molecules of Streptococcus mutans, though the mechanism of their regulation has not been fully elucidated. METHODS: To investigate the regulation mechanism, we determined a nucleotide sequence in the upstream region of the pac locus in S. mutans and identified two open reading frames (ORF), designated as orf1 and orf2. Each ORF was inactivated and functional analyses were performed. RESULTS: Western blot analyses revealed that the expression level of PAc was unaffected, while that of cell-associated GTF was diminished in both mutant strains. Furthermore, they showed higher hydrophobicity levels and an impaired sucrose-dependent adherence to smooth surfaces. RNA dot blot analysis demonstrated that transcriptions of the gtfB and the gtfC genes, which encode GTF-I and GTF-SI, respectively, were downregulated, while that of pac was comparable to the wild-type strain. In addition, the GTF activities of the mutant strains were significantly lower than those of the wild-type, though a greater amount of total glucan produced by the mutants was noted in culture supernatants. CONCLUSION: These findings suggest that orf1 and orf2 are associated with positive regulation of the gtfB and gtfC genes.

Difference in intracortical inhibition of the motor cortex between cortical myoclonus and focal hand dystonia.

OBJECTIVE: The short interval intracortical inhibition (SICI) of the motor cortex (M1) is reduced in both cortical myoclonus and focal hand dystonia. This reduction has been attributed to the dysfunction of GABAergic system within the motor cortex. However, the precise mechanisms underlying the reduction may not be entirely identical in these two disorders, being due to primary pathological involvement in M1 or secondary to functional changes outside M1. The aim of this study was to elucidate possible differences in intracortical inhibition between these two disorders. METHODS: Subjects were 11 patients with benign myoclonus epilepsy, 7 with focal hand dystonia, and 11 normal volunteers. We studied SICI using anterior-posterior (AP) directed and posterior-anterior (PA) directed induced currents in the brain. RESULTS: In both disorders, SICI with PA-directed currents was reduced as reported previously. In contrast, SICI studied with AP currents was normal in patients with focal hand dystonia, but reduced in patients with cortical myoclonus. CONCLUSIONS: The difference between the two disorders might reflect the underlying pathological difference. In cortical myoclonus, the inhibitory interneurons of the motor cortex are affected, whereas the same interneurons are intact in dystonia. The difference in SICI induced by AP and PA directed currents in dystonia may be explained by the following possibilities: the difference in composition of I-waves contributing to EMG generation and the difference in modulation of the interneuronal activity by voluntary contraction. These changes may be secondary to dysregulation of the motor cortex by the basal ganglia or related cortices in dystonia. SIGNIFICANCE: The SICI using AP directed currents together with the conventional SICI using PA directed currents was able to demonstrate some difference in the intrinsic circuits of M1 between myoclonus and focal hand dystonia. SICI using AP directed currents can provide additional information about the motor cortical excitability changes over those obtained by the previously reported methods.

The effect of sevoflurane-induced hypotension in combination with acute hypervolaemic haemodilution on middle cerebral artery flow velocity in surgical patients.

BACKGROUND AND OBJECTIVE: This study was carried out to clarify the effect of the combination of acute hypervolaemic haemodilution and hypotensive anaesthesia induced with sevoflurane on human middle cerebral artery flow velocity using transcranial Doppler ultrasonography. METHODS: Thirty patients who were maintained with N2O-O2-sevoflurane anaesthesia undergoing hip surgery were randomly divided into two groups (no controlled hypotension group, Group A, and controlled hypotension group, Group B). Haemodilution was produced by acute preoperative infusion of 1000 mL of hydroxyethylstarch without removing blood in both groups. Mean arterial pressure was maintained at approximately 95 mmHg in Group A and at 55 mmHg for 80 min by increasing the inspired concentration of sevoflurane in Group B. Middle cerebral artery flow velocity was measured before haemodilution, after haemodilution, 80 min after starting hypotension, and 60 min after recovery from hypotension. RESULTS: Middle cerebral artery flow velocity significantly increased in both groups after haemodilution; by 28%, in Group A, P < 0.05 vs. before haemodilution and by 30% vs. before haemodilution in Group B, P < 0.05). During controlled hypotension, it decreased towards the pre-haemodilution value (P < 0.05 vs. after haemodilution). CONCLUSIONS: Sevoflurane-induced hypotension to a mean arterial pressure of 55 mmHg would reduce middle cerebral artery flow that had been increased by acute hypervolaemic haemodilution, such as haematocrit value of 26%, whereas it could preserve the flow in pre-haemodilution condition during normocapnia.

Inflammatory immune responses by water-insoluble alpha-glucans.

Water-insoluble alpha-glucans are synthesized from sucrose by glucosyltransferase-I of mutans streptococci and play an important role in the development of dental plaque. Several types of beta-glucans in fungal cell wall components and water-soluble alpha-glucans from Streptococcus mutans are known to modulate innate immunity. In the present study, we investigated whether water-insoluble alpha-glucans also induced inflammatory innate immune responses. Our results showed that water-insoluble alpha-glucans synthesized by Streptococcus sobrinus activated mouse peritoneal exudate macrophages to produce pro-inflammatory cytokines. The immunological responses were not due to contamination by sucrose, water-soluble alpha-glucan, lipopolysaccharide, or peptidoglycan. Furthermore, human monocytes stimulated by water-insoluble alpha-glucans produced TNF-alpha and IL-8, while human polymorphonuclear cells were activated by water-insoluble alpha-glucans, resulting in chemotaxis and hydrogen peroxide production. The results demonstrated that water-soluble alpha-glucans modulate macrophage- and granulocyte-induced inflammatory immune responses, and suggest that inflammation induced by those alpha-glucans is associated with the development of periodontal diseases.

Differential Expression and Roles of Secreted Frizzled-Related Protein 5 and the Wingless Homolog Wnt5a in Periodontitis.

The Wingless/integrase-1 (Wnt) family of protein ligands and their functional antagonists, secreted frizzled-related proteins (sFRPs), regulate various biological processes ranging from embryonic development to immunity and inflammation. Wnt5a and sFRP5 comprise a typical ligand/antagonist pair, and the former molecule was recently detected at the messenger RNA (mRNA) level in human periodontitis. The main objective of this study was to investigate the interrelationship of expression of Wnt5a and sFRP5 in human periodontitis (as compared to health) and to determine their roles in inflammation and bone loss in an animal model. We detected both Wnt5a and sFRP5 mRNA in human gingiva, with Wnt5a dominating in diseased and sFRP5 in healthy tissue. Wnt5a and sFRP5 protein colocalized in the gingival epithelium, suggesting epithelial cell expression, which was confirmed in cultured human gingival epithelial cells (HGECs). The HGEC expression of Wnt5a and sFRP5 was differentially regulated by a proinflammatory stimulus (lipopolysaccharide [LPS] from Porphyromonas gingivalis) in a manner consistent with the clinical observations (i.e., LPS upregulated Wnt5a and downregulated sFRP5). In HGECs, exogenously added Wnt5a enhanced whereas sFRP5 inhibited LPS-induced inflammation, as monitored by interleukin 8 production. Consistent with this, local treatment with sFRP5 in mice subjected to ligature-induced periodontitis inhibited inflammation and bone loss, correlating with decreased numbers of osteoclasts in bone tissue sections. As in humans, mouse periodontitis was associated with high expression of Wnt5a and low expression of sFRP5, although this profile was reversed after treatment with sFRP5. In conclusion, we demonstrated a novel reciprocal relationship between sFRP5 and Wnt5a expression in periodontal health and disease, paving the way to clinical investigation of the possibility of using the Wnt5a/sFRP5 ratio as a periodontitis biomarker. Moreover, we showed that sFRP5 blocks experimental periodontal inflammation and bone loss, suggesting a promising platform for the development of a new host modulation therapy in periodontitis.

Hemispheric lateralization in the cortical motor preparation for human vocalization.

To investigate the cortical information processing during the preparation of vocalization, we performed transcranial magnetic stimulation (TMS) over the cortex while the subjects prepared to produce voice in response to a visual cue. The control reaction time (RT) of vocalization without TMS was 250-350 msec. TMS prolonged RT when it was delivered up to 150-200 msec before the expected onset of voice (EOV). The largest delay of RT was induced bilaterally over points 6 cm to the left and right of the vertex (the left and right motor areas), resulting in 10-20% prolongation of RT. During the early phase of prevocalization period (50-100 msec before EOV), the delay induced over the left motor area was slightly larger than that induced over the right motor area, whereas, during the late phase (0-50 msec before EOV), it was significantly larger over the right motor area. Bilateral and simultaneous TMS of the left and right motor areas induced delays not significantly different from that induced by unilateral TMS during the early phase, but induced a large delay well in excess of the latter during the late phase. Thus, during the cortical preparation for human vocalization, alternation of hemispheric lateralization takes place between the bilateral motor cortices near the facial motor representations, with mild left hemispheric predominance at the early phase switching over to robust right hemispheric predominance during the late phase. Our results also suggested involvement of the motor representation of respiratory muscles and also of supplementary motor cortex.

Sequential production of Birbeck granules through adsorptive pinocytosis.

A case of vitiligo with inflammatory raised borders was observed electron microscopically, resulting in an interesting view of the formation of Birbeck granules in Langerhans cells. Following the formation of larger coated vesicles, which perform adsorptive pinocytosis from the cell membrane, membrane invagination of the cell occurred shown as the tubular infolding, resulting in the observation of the characteristic Birbeck granule band pattern in its interior. This phenomenon supports the theory of Hashimoto and Tarnowski (1968) that Birbeck granules are formed from the infolding of the cell membrane. In addition, our study shows the involvement of adsorptive pinocytosis in the formation of the granules. It was suggested that when the coated Birbeck granule shifts into the cell, possibly its coat is detached and the vesicle portion forms the globule of the Birbeck granule.

Quantification of two aromatic amine mutagens, PBTA-1 and PBTA-2, in the yodo river system.

The levels of two aromatic amine mutagens, 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5-a mino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), were quantitatively analyzed in the Yodo River system in Japan. The river water samples were collected at nine sampling sites from the Yodo River system twice or three times between May and July in 1997. PBTA-1 and PBTA-2 in the river water samples were concentrated on blue rayon columns, partially purified by high-performance liquid chromatography (HPLC) on reverse-phase columns, then quantified by HPLC with an electrochemical detector. The amounts of PBTA-1 and PBTA-2 in the water samples were < 0.01-1.91 and < 0.01-2.25 ng/L, respectively. High levels of PBTA-1 and PBTA-2 were detected in the samples collected within 4 km downstream of two sewage plants, which are located along the banks of the Nishitakase River, a tributary of the Yodo River system, and these samples showed stronger mutagenicity in Salmonella typhimurium YG1024 with S9 mix than the other water samples. On the other hand, the river water samples from upstream of the sewage plant were weakly or not mutagenic and PBTA-1 and PBTA-2 were not detected. These results confirmed that a major source of PBTA-1 and PBTA-2 in the Yodo River system is effluent from the sewage plants and that discharged mutagens, including PBTA-1 and PBTA-2, are diluted and/or decomposed while moving down the Yodo River system.

Enzymatic transesterification with the lipase from Pseudomonas fragi 22.39 B in a non-aqueous reaction system.

The lipase from Pseudomonas fragi 22.39 B catalyzed the transesterification in ester and alcohol mixtures without any other solvent. Activated esters, such as vinyl and phenyl esters, were excellent acyl donors for the reaction, and the activity was enhanced by increasing the carbon number of the fatty acid fraction of the esters. Primary alcohols were esterified faster than secondary ones in this reaction system, while tertiary alcohols such as alpha-terpineol did not react at all. The lipase exhibited stereoselectivity in the esterification of alcohols such as 2-octanol.

Production of optically active esters and alcohols from racemic alcohols by lipase-catalyzed stereoselective transesterification in non-aqueous reaction system.

Microbial lipase-catalyzed transesterification between vinyl acetate and (RS)-2-octanol or (RS)-1-phenylethanol was investigated in a reaction system without addition of aqueous or organic solvents. From a screening test with various lipases, it was found that the enzymes from Pseudomonas species could efficiently catalyze the reaction, and R-enantiomers of the racemic alcohols were preferentially esterified by them. Enantiomeric purities of the optically active alcohols (S) and esters (R) obtained from (RS)-1-phenylethanol by the stereoselective transesterification of these lipases were all more than 95%.

Nucleotide sequence and molecular characterization of a gene encoding GTP-binding protein from Streptococcus gordonii.

A 1286-bp fragment of chromosomal DNA from Streptococcus gordonii strain Challis was cloned and sequenced. The gene sgg consisted of 897-bp nucleotides encoding a 299-amino acid polypeptide (33,200 Da). The deduced amino acid sequence exhibited significant similarity to Era, G protein of Escherichia coli. The nucleotide binding assay demonstrated that recombinant Sgg bound [32P]GTP but not [32P]ATP, [32P]CTP, or [32P]UTP. These findings indicate that Sgg is a member of the G protein superfamily in the genus Streptococcus.

Molecular analyses of glucosyltransferase genes among strains of Streptococcus mutans.

Three glucosyltransferase (GTase) genes (gtfB, gtfC and gtfD) were cloned and sequenced from clinically isolated strains of Streptococcus mutans MT8148 (serotype c), MT4239 (c), MT4245 (e), MT4467 (e) and MT4251 (f), respectively. Comparison of the gtf genes revealed that interstrain difference of gtfB and gtfD was limited, while gtfC showed significant interstrain variations. Similar to gtfB and gtfD, gtfC possessed five direct repeats composed of homologous unit in the carboxyl-terminal portion. The repeating unit consisted of 63-65 amino acid residues and is responsible for glucan binding. The gtfC gene from S. mutans MT4245 lacked the fourth unit. Multiple alignment with the gtf sequence of strain GS-5 (c) revealed several changes in these gtf genes due to frameshift mutations. The peptides encoded by the gtfB, gtfC and gtfD genes of GS-5 were 1, 80, and 32 amino acid residues shorter than those of the test strains except strain MT4245.

Predominant activation of I1-waves from the leg motor area by transcranial magnetic stimulation.

We performed transcranial magnetic stimulation (TMS) to elucidate the D- and I-wave components comprising the motor evoked potentials (MEPs) elicited from the leg motor area, especially at near-threshold intensity. Recordings were made from the tibialis anterior muscle using needle electrodes. A figure-of-eight coil was placed so as to induce current in the brain in eight different directions, starting from the posterior-to-anterior direction and rotating it in 45 degrees steps. The latencies were compared with those evoked by transcranial electrical stimulation (TES) and TMS using a double cone coil. Although the latencies of MEPs ranged from D to I3 waves, the most prominent component evoked by TMS at near-threshold intensity represented the I1 wave. With the double cone coil, the elicited peaks always represented I1 waves, and D waves were evoked only at very high stimulus intensities, suggesting a high effectiveness of this coil in inducing I1 waves. Using the figure-of-eight coil, current flowing anteriorly or toward the hemisphere contralateral to the recorded muscle was more effective in eliciting large responses than current flowing posteriorly or toward the ipsilateral hemisphere. The effective directions induced I1 waves with the lowest threshold, whereas the less effective directions elicited I1 and I2 waves with a similar frequency. Higher stimulus intensities resulted in concomitant activation of D through I3 waves with increasing amount of D waves, but still the predominance of I1 waves was apparent. The amount of I waves, especially of I1 waves, was greater than predicted by the hypothesis that TMS over the leg motor area activates the output cells directly, but rather suggests predominant transsynaptic activation. The results accord with those of recent human epidural recordings.

Somatosensory evoked high-frequency oscillation in Parkinson's disease and myoclonus epilepsy.

AIM: A high-frequency oscillation in the range of 600-900 Hz has been shown to be a component of the somatosensory evoked potential (SEP) in humans. In the present communication, we studied these oscillation potentials in two neurological disorders. SUBJECTS AND METHODS: Subjects were 20 healthy volunteers, 17 patients with Parkinson's disease (PD) and 3 with myoclonus epilepsy (ME). Median nerve SEPs were recorded using filters set at 0.5 and 3000 Hz. Several peaks of oscillation were obtained by digitally filtering raw SEPs from 500 to 1000 Hz, and their amplitudes and onset latencies were measured. RESULTS: In normal subjects, several oscillation potentials were observed at the latency of 0 to 8 ms after the onset of N20. In PD patients, the oscillation potentials at normal latencies were significantly larger than those of normal subjects. Moreover, in 7 of 17 PD patients, they were extremely enlarged (>mean +/- 3 SD of normal values). In contrast, in patients with ME, abnormally enlarged oscillation potentials were seen at longer latencies (7-14 ms) in spite of normal-sized early oscillation potentials. Magnetoencephalographic analyses showed that any oscillation potentials originated from the primary sensory cortex. CONCLUSIONS: There are at least two mechanisms for producing the oscillation potentials of SEP. Those around N20 have some relation with the basal ganglia function and are enlarged in PD patients, the others around P25-N33 are enhanced in ME patients.

The human hand motor area is transiently suppressed by an unexpected auditory stimulus.

OBJECTIVE: To study the effect of a loud auditory stimulus on the excitability of the human motor cortex. METHODS: Ten normal volunteers participated in this study. The size of responses to transcranial magnetic or electrical cortical stimulation (TMS or TES) given at different times (ISIs) after a loud sound were compared with those to TMS or TES alone (control response). Different intensities and durations of sound were used at several intertrial intervals (ITIs). In addition, we examined how the presence of a preceding click modulated the effect of a loud sound (prepulse inhibition). The incidence of startle response evoked by various stimuli was also studied. RESULTS: A loud auditory stimulus suppressed EMG responses to TMS when it preceded the magnetic stimulus by 30-60 ms, whereas it did not affect responses to TES. This suggests that the suppression occurred at a cortical level. Significant suppression was evoked only when the sound was louder than 80 dB and longer than 50 ms in duration. Such stimuli frequently elicited a startle response when given alone. The effect was not evoked if the ITI was 5 s, but was evoked when it was longer than 20 s. A preceding click reduced the suppression elicited by loud sounds. CONCLUSIONS: Auditory stimuli that produced the greatest effect on responses to TMS had the same characteristics as those which yielded the most consistent auditory startle. We suggest that modulation of cortical excitability occurs in parallel with the auditory startle and both may arise from the same region of the brain-stem.