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Different in vivo repopulating activities of purified hematopoietic stem cells before and after being stimulated to divide in vitro with the same kinetics.

OBJECTIVE: The Hoechst 33342-effluxing side population (SP) of adult mouse bone marrow (BM) contains most of the hematopoietic stem cells (HSCs). Here we measured the HSC content of specific subsets of SP cells and then used a highly HSC-enriched fraction to investigate the effect of different growth factors on the initial rate of HSC proliferation in vitro and the accompanying maintenance (or loss) of HSCs in the first-division progeny. MATERIALS AND METHODS: Staining with Rhodamine-123 (Rho) was used to subfractionate lineage marker-negative (lin-) SP cells. Cells were assayed for HSCs by examining their ability to generate sustained (>4 months) multi-lineage lympho-myeloid clones in irradiated hosts. Cultures of single lin- Rho- SP cells were used to monitor growth factor effects on HSC proliferation and function. RESULTS: More than 40% of mice injected with single lin- Rho- SP cells showed long-term lympho-myeloid reconstitution. Some clones peaked within 8 weeks but others developed more slowly apparently unrelated to the pattern of lineage representation. 3/3 clones tested repopulated secondary mice. Either Steel factor+interleukin-11 (+/- flt3-ligand) or Steel factor+thrombopoietin stimulated at least 75% of single lin- Rho- SP cells to divide in vitro with the same synchronous kinetics. However, in the first cocktail, the frequency of HSCs among the first-division doublets was preserved but in the latter it was greatly diminished. CONCLUSION: Exogenous growth factors can differentially affect the ability of HSCs to execute a self-renewal division within a single cell cycle even when the kinetics of proliferation are the same.

Animals↗

The calcimimetic agent KRN 1493 lowers plasma parathyroid hormone and ionized calcium concentrations in patients with chronic renal failure on haemodialysis both on the day of haemodialysis and on the day without haemodialysis.

AIMS: Treatment with vitamin D sterols can lower plasma parathyroid hormone (PTH) in patients with secondary hyperparathyroidism; however, hypercalcaemia, hyperphosphataemia, or both, often develop. Calcimimetic agents, employed in alternative therapeutic approaches, directly inhibit PTH secretion by activating the calcium-sensing receptor in the parathyroid glands. METHODS: In this study, patients were given orally 25, 50, and 100 mg doses of the calcimimetic agent KRN 1493 each on two occasions, on the day of haemodialysis and on the day without haemodialysis. RESULTS: In the pharmacokinetic results, because the clearance of KRN 1493 by haemodialysis was much smaller than the systemic clearance, the influence of haemodialysis was not remarkable. In the pharmacodynamic study, on both the days with or without haemodialysis, plasma PTH concentrations decreased in a dose-dependent manner. Serum calcium concentrations decreased in association with the decrease in plasma PTH concentrations. Mild dose-dependent adverse effects (mainly nausea) were seen after the administration of KRN 1493 on both the day of haemodialysis and the day without haemodialysis. CONCLUSIONS: We conclude that the pharmacokinetics of KRN 1493 after a single administration were similar on the day of haemodialysis and the day without haemodialysis. KRN 1493 is safe and effective in suppressing PTH secretion and serum calcium concentrations on the day of haemodialysis and on the day without haemodialysis in patients with secondary hyperparathyroidism.

Administration, Oral↗

Transjugular intrahepatic portosystemic shunt with silicone-covered Wallstents: results in a swine model.

PURPOSE: To evaluate the use of impermeable silicone-covered Wallstents for transjugular intrahepatic portosystemic shunt creation. MATERIALS AND METHODS: A transjugular intrahepatic portosystemic shunt was created in 14 young swine (weight, 20-32 kg) by using impermeable silicone-covered Wallstents. In eight animals, the silicone covering extended from the portal vein to the inferior vena cava. In two swine, the silicone covering ended short of the inferior vena cava, in two it ended short of the portal vein wall, and in two it ended short at each end. Follow-up transhepatic portal venography was performed weekly for 6 weeks or until the shunt was occluded. Animals were then sacrificed for gross and histologic evaluation. RESULTS: Only two of 14 shunts were patent after 3 weeks; both were stenosed with luminal narrowing of more than 50% in the middle of the shunt. By 6 weeks, all shunts were occluded. At histologic evaluation, a marked foreign-body reaction with superimposed thrombosis was demonstrated. CONCLUSION: In comparison with uncovered Wallstents, impermeable silicone-covered Wallstents are associated with decreased patency at transjugular intrahepatic portosystemic shunt creation. This is likely due to increased thrombogenicity and a foreign-body reaction.

Animals↗

Convalescent stage coronary flow reserve and late myocardial morphologic outcomes in patients with first anterior acute myocardial infarction.

BACKGROUND: Microvascular damage immediately after reperfusion therapy is an independent predictor of left ventricular function in patients with acute myocardial infarction (AMI). However, its recovery may vary among individuals and the relationship between convalescent stage microvasculature and late myocardial morphologic change is unclear. METHODS AND RESULTS: Patients treated with coronary angioplasty within 12 h of their first anterior AMI were enrolled in this study. Coronary flow reserve (CFR) was measured 3 weeks post AMI, in both branches of the left coronary artery: culprit (left anterior descending artery: LAD) and non-culprit (left circumflex artery: LCX). Left ventriculography was performed at 3 weeks and 6 months post AMI and compared. Seventeen patients showed abnormal CFR in the LAD (Group 1: CFR<2), whereas 20 patients showed normal CFR (Group 2: CFR >/=2). Percent changes of end-diastolic volume tended to be higher in Group 1 than in Group 2 (11.8+/-21.6% vs -1.3+/-14.4%, p=0.056), and %changes of end-systolic volume was significantly smaller in Group 2 (11.8+/-22.1% vs -8.7+/-25.1%, p<0.05). A statistically significant correlation was found between absolute and relative CFR in the LAD and %change of end-systolic volume (r=-0.58: p<0.001, and r=0.40: p<0.05, respectively). CONCLUSIONS: Microvascular function in the convalescent stage may be related to these favorable changes.

Aged↗

[Vitrectomy for proliferative diabetic retinopathy].

PURPOSE: We reviewed the outcome of vitrectomy for proliferative diabetic retinopathy (DR) and evaluated factors affecting the final visual outcome. METHODS: We performed primary vitreous surgery for proliferative DR in 148 eyes of 118 cases in three years from July 1999 to August 2002. All cases were followed for at least 3 months. We excluded vitreous surgery for diabetic maculopathy. Ages ranged from 24 to 80 (mean 57) years. Average postoperative follow-up period was 15 months. We evaluated the stage of DR by the new Fukuda classification. RESULT: Preoperative classification consisted of BIV (54 eyes, 36%), BV (94 eyes, 64%), and BV + VI (36 eyes). Final visual acuity was improved by 2 lines or more in 102 eyes (69%), remained unchanged in 28 eyes (19%), and decreased by two lines or more in 18 eyes (12%). There was a statistical correlation between preoperative visual acuity and final visual acuity. Earlier stages of DR had better visual outcome. Compared to the surgical outcome in the 1990s, the percentage of worsened eyes decreased. CONCLUSION: Vitrectomy for proliferative DR may be beneficial if performed in the earlier stages of DR or if the patient has better visual acuity before vitrectomy.

Adult↗

Effective repetitive dystrophin gene transfer into skeletal muscle of adult mdx mice using a helper-dependent adenovirus vector expressing the coxsackievirus and adenovirus receptor (CAR) and dystrophin.

BACKGROUND: The helper-dependent adenovirus (HDAd) vector is less immunogenic and has a larger cloning capacity of up to 37 kb enough to carry the full-length dystrophin cDNA. However, high and long-term expression of dystrophin transduced to mature muscle still remains difficult. One of the main reasons for this is that the expression of the coxsackievirus and adenovirus receptor (CAR) is very low in mature muscle. METHODS: We have constructed two different HDAd vectors. One contains the LacZ and the murine full-length dystrophin expression cassette (HDAdLacZ-dys), and the other is a new, improved vector containing the CAR and the dystrophin expression cassette (HDAdCAR-dys). RESULTS: We initially demonstrated high dystrophin expression and prevention of the dystrophic pathology in mdx muscle injected during the neonatal phase with HDAdLacZ-dys. Furthermore, we demonstrated that repeated injections of HDAdCAR-dys into mature muscle led to approximately nine times greater dystrophin-positive fibers in number than a single injection, thereby recovering the expression of dystrophin-associated proteins. This data has also shown that HDAdCAR-dys enabled administration of adenovirus (Ad) vector to the host with pre-existing immunity to the same serotype of Ad. CONCLUSIONS: Repetitive injections of the HDAd vector containing the CAR and the dystrophin expression cassette could improve the efficiency of subsequent dystrophin gene transfer to mature mdx muscle. This result suggests that our new HDAd vector will provide a novel gene therapy strategy for Duchenne muscular dystrophy, raising the prospects for gene therapy of other hereditary myopathies.

Adenoviridae↗

Characterization of prostatic neuroendocrine cell line established from neuroendocrine carcinoma of transgenic mouse allograft model.

BACKGROUND: The role of neuroendocrine (NE) cells in prostate cancer remains unclear. A useful model is necessary to study the biology of NE cells. We herein describe the establishment and characterization of an immortalized cell line from an NE-10 allograft of murine prostatic NE carcinoma. METHODS: A novel cell line, designated NE-CS, was developed from an NE-10 allograft that was established from the ventral prostate of the LPB-T-antigen (Tag) transgenic mouse, line 10 (12T-10). We investigated the growth, karyotype, electron microscopic findings, expression of Tag and androgen receptor (AR), and tumorigenesis of the cells in athymic mice. RESULTS: The immortal cell line NE-CS was maintained in vitro for more than 2 years. The NE-CS cells had dendritic-like extensions with dense core granules in the cytoplasm and produced serotonin and somatostatin in conditioned medium. The cells expressed neither Tag nor AR. They showed androgen-independent growth in vitro and a hypotetraploid karyotype similar to the original NE-10 allograft. The NE-CS cells, which were subcutaneously inoculated into athymic mice, formed tumors with the NE phenotype. The tumors exhibited accelerated growth compared to the original NE-10 allograft. CONCLUSIONS: The established cell line has characteristics of NE differentiation and tumorigenic ability. This cell line may be a promising model to understand the molecular mechanisms associated with the acquisition of hormone refractory prostate cancer.

Animals↗

Experimental TIPS with spiral Z-stents in swine with and without induced portal hypertension.

PURPOSE: To assess the suitability of spiral Z-stents for transjugular intrahepatic portosystemic shunt (TIPS) and the influence of portal hypertension on shunt patency in young swine. METHODS: TIPS were established using spiral Z-stents in 14 domestic swine. In 7 animals, the portal venous pressure was normal; in the other 7, acute portal hypertension was induced by embolization of portal vein branches. Follow-up portal venography and histologic evaluations were done from 1 hr to 12 weeks after TIPS. RESULTS: Follow-up transhepatic portal venograms showed progressive narrowing of the shunt, most prominent in the midportion of the tract. Ingrowth of liver parenchyma between the stent wires found after 3 weeks led to progressive shunt narrowing and shunt occlusion by 12 weeks. A pseudointima grew rapidly inside the stent, peaked in thickness around 4 weeks, and decreased later. Acutely created portal hypertension rapidly returned to normal and there was no difference in TIPS patency between the two groups of animals. CONCLUSION: Although the spiral Z-stent can be used as a device for creation of TIPS in patients with cirrhotic livers, it is associated with extensive liver ingrowth in swine that leads to rapid shunt occlusion. Portal hypertension was only transient in this model.

Animals↗

Effects of oral theophylline on sick sinus syndrome.

OBJECTIVES: We sought to determine the effect of theophylline on cardiac pauses in sick sinus syndrome. BACKGROUND: Sick sinus syndrome, a relatively benign condition, is usually treated with pacemaker implantation without any proved effectiveness. Thus, an appropriate pharmacologic therapy would be useful. METHODS: Theophylline (200 to 400 mg/day for 1 month) was initially administered orally to 17 patients with sick sinus syndrome, which is manifested by sinus pauses of > 2.5 s. Eleven of the 17 patients subsequently received theophylline for an additional 8 to 37 months. Twenty-four-hour Holter recordings were obtained before treatment, at the end of 1 month of treatment and then at 6-month intervals. RESULTS: Theophylline decreased the frequency of sinus pauses from 256 +/- 230 to 23 +/- 62 pauses per 24 h and decreased the duration of the longest pauses from 4.7 +/- 1.8 to 2.2 +/- 0.97 s after 1 month of treatment. Subjective symptoms associated with cardiac pauses disappeared in 16 of 17 patients. Ventricular premature beats increased in frequency but did not last longer than two beats. Three patients experienced adverse effects. Nine of the 11 patients receiving long-term treatment had a good outcome, but 2 patients required a pacemaker because of the reappearance of long sinus pauses. CONCLUSIONS: The results suggest that oral theophylline may be beneficial for the treatment of patients with sick sinus syndrome.

Administration, Oral↗

Comparison of limited and anatomic hepatic resection for hepatocellular carcinoma with hepatitis C.

BACKGROUND: The long-term outcome after resection of hepatocellular carcinoma is influenced by factors related to the tumor and the underlying liver disease. The prognosis of hepatocellular carcinoma is worse in hepatitis C virus antibody-positive patients than in hepatitis B surface antigen-positive patients. In patients with hepatitis C virus infection and hepatocellular carcinoma, the optimum extent of operative resection, i.e., limited versus anatomic, remains controversial. METHODS: Among 247 patients with hepatitis C virus infection who underwent curative resection of hepatocellular carcinoma between 1992 and 2003, 213 patients received limited resection and 34 patients had anatomic resection of at least two Couinaud subsegments with complete removal of the portal territory containing the tumor. The clinical characteristics, operative results, and long-term survival of these two groups were compared. RESULTS: Although the patients receiving limited resection had significantly worse preoperative liver function than the patients undergoing anatomic resection, the postoperative liver function of the limited resection group was significantly better. The mortality and morbidity rates were not significantly different after limited and anatomic resection. Disease-free survival and overall survival were similar after both types of resection, as were the incidence and pattern of intrahepatic tumor recurrence. CONCLUSIONS: In patients with hepatitis C virus infection and hepatocellular carcinoma, anatomic resection does not provide any significant benefit and should not be carried out unless it is technically necessary. In patients with a limited hepatic functional reserve, removal of the tumor with preservation of the liver parenchyma may take priority over wide resection.

Aged↗

Expression of heregulin alpha, erbB2, and erbB3 and their influences on proliferation of gastric epithelial cells.

BACKGROUND & AIMS: Heregulins (HRGs) regulate the proliferation and differentiation of various cell types. However, very little is known about their function in the gastrointestinal tract. The aim of this study was to investigate the role of HRGs on gastrointestinal cells. METHODS: We examined the expression of erbB receptors and HRG-alpha in human gastric cancer cell lines, rat gastrointestinal epithelial cells, and human gastric fibroblasts by Western blot analysis or reverse-transcription polymerase chain reaction. Receptor phosphorylation and heterodimerization induced by HRG-alpha were detected by Western blot analysis. We also evaluated the in vitro effects of HRG-alpha on cell proliferation and restitution. RESULTS: Cancer cell lines and rat epithelial cells expressed erbB2 and erbB3, but protein expression of erbB4 was not detected. HRG-alpha was detected only in gastric fibroblasts. HRG-alpha activated tyrosine phosphorylation of epidermal growth factor receptor (EGFR), erbB2, and erbB3 and induced not only erbB3/erbB2 but also erbB3/EGFR and erbB2/EGFR heterodimer formation in MKN-28 cancer cells. Simultaneous cultivation of MKN-28 cells with gastric fibroblasts resulted in tyrosine phosphorylation of erbB3 in MKN-28 cells. HRG-alpha also stimulated proliferation of MKN-28 cells and gastric epithelial cells. CONCLUSIONS: The data suggest that HRG-alpha may affect epithelial cell proliferation through mesenchymal-epithelial interaction in the gastric mucosa.

Animals↗

Altered glomerular localization of heparan sulfate proteoglycan in experimental nephritides.

The distribution of heparan sulfate proteoglycan (HS-PG) was examined electron microscopically by the high iron diamine (HID) method in puromycin aminonucleoside (PAN) nephrosis, accelerated Masugi nephritis (NTN), and serum sickness nephritis induced by bovine serum albumin (BSA nephritis) in the rat. In PAN nephrosis rats, no change was observed in the distribution of HS-PG in the lamina rara externa (LRE) of the glomerular basement membrane (GBM) throughout the experiment. In NTN rats, however, the loss of HS-PG was observed, and it was associated with subepithelial electron dense deposits formed possibly by serum sickness mechanism, but not with inflammatory cell infiltration. In BAS nephritis, immune deposits were seen in mesangial, subendothelial, intramembranous and subepithelial areas. The deposits in the former three areas seemed to have little reciprocity with the loss of HS-PG and proteinuria. Urinary protein increased in accordance with the development of subepithelial deposits and the loss of HS-PG in the area of the deposits in the LRE. These results indicate that HS-PG could be preserved even in marked proteinuric states in morphologically intact basement membrane, but altered and lost distribution of HS-PG associated with subepithelial immune deposits could in turn result in the development of proteinuria.

Animals↗

Clinical significance of p53, MDM2 and bcl-2 expression in transitional cell carcinoma of the bladder.

We investigated the prognostic and predictive relevance of p53, MDM2, and bcl-2 protein expression in patients with transitional cell carcinoma (TCC) of the bladder. The expression of p53, MDM2 and bcl-2 protein was studied by immunohistochemical methods in paraffin-embedded specimens from 119 patients whose clinicopathologic data confirmed TCC of the bladder. Multivariate analyses of prognostic factors were performed, and correlations with classical clinicopathologic parameters were examined. Sixty-one, 12, and 17% of cases were considered positive for expression of p53, MDM2 and bcl-2, respectively. p53 expression correlated with stage (p=0.0209), but not MDM2 and bcl-2 with any clinicopathologic parameters. In Cox's regression analysis, staging demonstrated a statistically worse prognosis (hazard ratio 1.636; p=0.0059) while bcl-2 (hazard ratio 0.179; p=0.0474) expression showed favorable prognosis in stage T2-4 invasive TCC of the bladder. Co-expression with p53/MDM2 (hazard ratio 0.367; p=0.0401) and p53/bcl-2 (hazard ratio 3.487; p=0.0111) overexpression were associated with favorable and unfavorable prognosis in stage T2-4 invasive TCC of the bladder, respectively. Our results indicate that staging is the most useful parameter to predict clinical outcome in patients with TCC of the bladder. Determinations of bcl-2 and co-expression p53/MDM2 and p53/bcl-2 may be useful for predicting tumor behavior and prognosis in stage T2-4 invasive type TCC of the bladder.

Adult↗

[Comparison of the circadian variation of the time of onset of acute myocardial infarction and of attack of vasospastic angina without significant stenosis].

OBJECTIVES: To study the involvement of vasospasm as the trigger of acute myocardial infarction without significant stenosis, the circadian variation of the time of onset of acute myocardial infarction was compared with that of vasospastic angina without significant stenosis. METHODS: The subjects consisted of 3 groups, 64 patients with acute myocardial infarction without significant stenosis, 101 patients with acute myocardial infarction with one vessel disease and 98 patients with vasospastic angina without significant stenosis. The times of onset of acute myocardial infarction and spontaneous attack of vasospastic angina were recorded and classified according to the 4 periods (0:00-6:00, 6:00-12:00, 12:00-18:00, 18:00-24:00) and the pattern of distribution was compared between the 3 groups. RESULTS: The time distribution of acute myocardial infarction without significant stenosis showed a double peaked pattern at 6:00-12:00 and 18:00-24:00 and was similar to the pattern of acute myocardial infarction with one vessel disease(p = 0.93). Only a single peak in 0:00-6:00 was found in the pattern of distribution of vasospastic angina without significant stenosis and differed significantly from acute myocardial infarction(p < 0.01). CONCLUSIONS: The circadian variation of the time of onset of acute myocardial infarction was similar in patients with or without significant stenosis, and differed significantly from that in patients with vasospastic angina.

Angina Pectoris↗

Cyclooxygenase-2 gene disruption attenuates the severity of acute pancreatitis and pancreatitis-associated lung injury.

BACKGROUND & AIMS: Cyclooxygenase (COX) catalyzes the rate-limiting step in prostaglandin production; the inducible isoform, COX-2, has been implicated in a variety of inflammatory processes. The role of COX in acute pancreatitis and pancreatitis-associated lung injury is not known. METHODS: Acute pancreatitis was induced in Swiss Webster mice or mice deficient in the COX-2 (Ptgs2) or the COX-1 (Ptgs1) genes. Pancreata and lungs were harvested, and histologic sections of these tissues were scored. COX-2 expression, myeloperoxidase activity (a measurement of neutrophil sequestration), and serum amylase levels were determined. RESULTS: Acute pancreatitis was associated with induction of COX-2 expression. Treatment with NS-398 (a COX-2 inhibitor) significantly decreased the severity of pancreatitis. Furthermore, Ptgs2-deficient mice showed minimal histologic evidence of pancreatitis, a marked attenuation in the severity of lung injury, and a significant reduction in myeloperoxidase activity. In contrast, Ptgs1-deficient mice had pancreatitis and pulmonary inflammation, which was as severe or, in some instances, more severe than in the wild-type mice. CONCLUSIONS: Inhibition of COX-2 by either pharmacologic inhibition or selective genetic deletion markedly attenuated the severity of acute pancreatitis. Our findings identify the COX-2 isoform as an important regulator of the severity of acute pancreatitis and pancreatitis-associated lung injury.

Acute Disease↗

Five years experience of transrectal high-intensity focused ultrasound using the Sonablate device in the treatment of localized prostate cancer.

BACKGROUND: High-intensity focused ultrasound (HIFU) is a minimally invasive technique used in achieve coagulation necrosis. We evaluated biochemical disease-free survival rates, predictors of clinical outcome and morbidity in patients with localized prostate cancer treated with HIFU. METHODS: A total of 181 consecutive patients underwent HIFU with the use of Sonablate (Focus Surgery, Indianapolis, IN, USA). Biochemical recurrence was defined according to the criteria recommended by the American Society for Therapeutic Radiology and Oncology Consensus Panel. The median age and pretreatment prostate-specific antigen (PSA) level were 70 years (range 44-88) and 9.76 ng/mL (range 3.39-89.60). A total of 95 patients (52%) were treated with neoadjuvant hormones. The median follow-up period for all patients was 18.0 months (range 4-68). RESULTS: The biochemical disease-free survival rates at 1, 3 and 5 years in all patients were 84%, 80% and 78%, respectively. The biochemical disease-free survival rates at 3 years for patients with pretreatment PSA less than 10 ng/mL, 10.01-20.0 ng/mL and more than 20.0 ng/mL were 94%, 75% and 35%, respectively (P<0.0001). Multivariate analysis identified pretreatment PSA (P<0.0001) as a independent predictor of relapse. CONCLUSION: High-intensity focused ultrasound therapy appears to be a safe and efficacious minimally invasive therapy for patients with localized prostate cancer, especially those with a pretreatment PSA level less than 20 ng/mL.

Adult↗

Numerical chromosome aberrations in bladder cancer detected by in situ hybridization.

OBJECTIVE: To investigate the relationship between interphase cytogenetics and the grade and stage of bladder cancer in patients with transitional cell carcinomas of the urinary bladder. PATIENTS AND METHODS: By use of in situ hybridization with chromosome-specific DNA probes, the copy number of pericentromeric sequences on chromosomes 7, 10, 11, 17, 18, X and Y was detected within interphase nuclei in formalin-fixed and paraffin-embedded sections of the routinely processed bladder cancers from 20 patients. The percentage of hyperdiploid cells (three or more spots) was estimated using light microscopy. RESULTS: The percentage of hyperdiploid cells for chromosomes 7, 11 and 17 was highly correlated with increasing tumour grade (P < 0.01, Spearman rank correlation) or increasing pathological stage (P < 0.01). The percentage of hyperdiploid cells for chromosome Y was not correlated with either grade or stage (P > 0.05). As high tumour grade and stage are both indicative of more aggressive tumour behaviour and a worse prognosis, these findings suggest that the percentage of hyperdiploid cells, especially for chromosomes 7, 11 and 17, may be highly predictive of bladder tumour aggressiveness. CONCLUSION: These preliminary results suggest that measurement of numerical chromosome aberrations using in situ hybridization in bladder cancer may offer a new objective and quantitative assay of the biological potential of individual tumours.

Aged↗

Distribution of movement-related cortical potential upon jaw-biting in humans.

We examined the cerebral location of the readiness potential (hereinafter referred to as "RP") upon activation of the masseter muscle by voluntary and unilateral jaw-biting movement. Four normal adults served as subjects. Five scalp electrodes were placed according to the international 10-20 method at CZ, C3, C4, T3 and T4. In addition, in one of the subjects, RPs were recorded by 12 scalp electrodes in order to study changes occurring in the distribution of RPs with time. The maximum amplitude of the RP was located at T4 in the temporal area, which was involved in the biting movement as a negative slow potential occurring 1.4-0.8 s before the beginning of the discharge to the masseter muscle. The maximum amplitude of the RP on the contralateral side was located at T3. This meant that the amplitude of the RP tended to be higher on the same side as the biting movement than on the contralateral side in all subjects. From scalp topography, the maximum amplitude of the RP was shown to be confined to T4, and was especially marked immediately before the beginning of discharge to the masseter muscle. From these results it is thought that in the case of voluntary biting movement, the RP reflects activities of the pyramidal cells in the masticatory area of the cortex, and that strong descending impulses from both sides then reach the masseter muscles.

Action Potentials↗