[Experimental study on repair of bile duct defects with expanded polytetrafluoroethylene]

OBJECTIVE

To explore the possibility of repair of the extensive bile duct injuries with expanded polytetrafluoroethylene (ePTFE).

METHODS

A total of 36 local healthy hybrid dogs were employed to establish bile duct injury models by means of partial removal of bile duct (group A, 14 dogs), excision of a segmental duct (group B, 10 dogs), and ligation of the lower part of common bile duct(group C, 5 dogs; group D, 7 dogs). Group A were patched with ePTFE mesh, group B replaced by ePTFE tube. Interposition of the grafts between gallbladder and duedenum or jejunum was performed on group C and group D. The animals' postoperative performance status were evaluated. Cholangiography was used to define the patency of bile ducts. Tissues of bile ducts and liver were taken at 3 days, 2, 4, 8, 12 and 52 weeks for microscopic and ultrastructural examination to observe the healing process of bile duct and morphological changes in the liver.

RESULTS

Group A with ePTFE patch covered by epithelium had a high patency rate of 75%(9/12) and pathological damages were not found in the liver. The patency rate of group B was merely 40%(4/10), to some extent, accompanying damages in the liver. The grafts of group C and group D were fully expelled, ultimately leading to cystic-duodenal or cystic-jejunal fistulas formation.

CONCLUSION

The study suggests that application of ePTFE patch to repair bile duct defects is feasible.

Different classifications of UPOs in the parametrically different chaotic ISI series of a neural pacemaker

Various interspike intervals (ISIs) in a series of spontaneous discharges of experimental neural pacemakers were identified as chaotic and as lying between stable period 2 and stable period 3. The method of So et al. for detection of unstable periodic orbits (UPOs) was applied to analyze two chaotic ISI series generated under the action of [Ca2+]o in different concentrations. In the chaotic ISI series near the stable period 2, an unstable period 2 orbit was detected. In the chaotic ISI series near the stable period 3, both an unstable period 2 orbit and an unstable period 3 orbit were detected. The location of the unstable period 2 orbit was close to that of the stable period 2 in the return map, while the location of the unstable period 3 orbit was close to that of the stable period 3. The results not only revealed the structures of various chaotic ISI series, but also indicated that the classification of UPOs could reflect the experimental control parameters at which the chaotic ISI series were generated. The previously discovered period adding bifurcation in the ISI series generated by experimental neural pacemakers [12] was further described in terms of the evolution of the period orbits.

[Application of degree of complexity in heart rate variability analysis during orthostatic (correction of orthosatic) standing]

Objective. To introduce the degree of complexity in characterizing heart rate variability (HRV), and to discuss the changes in complexity of the cardiovascular system during orthostatic standing posture. Method. ECG of 8 subjects were recorded during supine and orthostatic standing postures. Degree of complexity was used to analyze the HRV. Result. Compared to supine before orthostatic standing posture, R-R intervals and its standard deviation at 0-5 min, 5-10 min, 10-15 min and 15-20 min during orthostatic standing posture were decreased significantly; the degree of complexity of HRV at 0-5 min and 15-20 min during orthostatic standing posture were decreased significantly; the approximate entropy of 0-5 min and 15-20 min were decreased significantly. Conclusion. The results showed that HRV and complexity of cardiovascular system was decreased during orthostatic standing. It was feasible that the degree of complexity can be used to analyze HRV.

[Effects of adaptive changes of vestibular system on cardiovascular regulation and orthostatic tolerance]

Astronauts may experience Space Adaptation Syndrome at the primary period in spaceflight. It is widely accepted that it is mainly caused by vestibular adaptive changes. The reverse changes of adaptation present after the return from weightlessness to normal 1 G. It may cause astronauts' postural instability and orthostatic intolerance. Evidences from animal model and some data from humans suggest that the vestibular system have influences on the sympathetic nervous system and cardiovascular control. The inputs that appear to be critical in producing these responses come from otolith receptors. The important medical problem--orthostatic intolerance in space medicine is mainly caused by cardiovascular abnormal control. It is possible that vestibular adaptive changes under microgravity may have its influence on the cardiovascular function and orthostatic intolerance.

[Changes of brain potentials related to auditory location discrimination during simulated weightlessness]

Objective. To study changes of brain response in distinguishing auditory location during simulated weightlessness. Method. The event-related potentials (ERPs) during auditory location discrimination were compared between head down tilt (HDT) and head up tilt (HUT) conditions among 14 healthy subjects. Result. (1) Both the target (T) and non-target (NT) auditory signals induced significant ERPS; (2) The slow potential was significantly lower for both T and NT-ERPs during HDT as compared with that during HUT; (3) The reduction of mean slow potential amplitude during HDT was more significant for the target signals from right-rear position and lightest for the target signals from right-front position. This phenomenon was more remarkable at left-front area. Conclusion. These data provide further evidence that the higher brain function was affected by simulated weightlessness.

Changes in vasoreactivity of rat pulmonary artery after 7 d tail-suspension

OBJECTIVE

To clarify the effects of simulated microgravity on the local regulating function of the pulmonary circulation.

METHOD

Rat tail-suspension (TS) was used as the animal model to simulate the effects of microgravity. The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique.

RESULT

As for the endothelium-intact vessel rings from TS group compared with those from the control (C) group, the contractile responses of pulmonary artery to potassium chloride (KCl, 10 ~ 70 mmol/L) did not change obviously after 7 d tail-suspension, which were markedly diminished as to phenylephrine (PE, 10(-9) ~ 10(-5) mol/L). The vasodilatory responses to acetylcholine (ACh, 10(-9) ~ 10(-5) mol/L) were markedly enhanced, which did not change obviously as to captopril (Cap, 10(-5) ~ 3 x 10(-3) mol/L). The vasoreactivity of endothelium-removed pulmonary artery rings to all vasoactive agents did not change after 7 d tail-suspension as compared with those from control rats.

CONCLUSION

The release of nitric oxide (NO) by rat pulmonary arterial endothelium was enhanced after 7 d tail-suspension. The vasodilatory function of pulmonary artery was enhanced.

[Changes of arterial blood pressure during various stages in spaceflight activities]

Arterial blood pressure (BP) is one of the four life signs in human beings, it could reflect cardiovascular function in some degrees. Thus, BP serves as an important cardiovascular parameter during various stages in foreign spaceflight activities. Although the reports about BP are not always in consistency during spaceflight, hypotension commonly occurs during orthostatic stress after spaceflight. The mechanisms of orthostatic intolerance after spaceflight are virtually the same as that of orthostatic hypotension after spaceflight. This paper simply reviewed the reports on BP during various stages in foreign spaceflight activities and the researches on the mechanism of orthostatic hypotension after spaceflight.

[Changes in electrocardiogram and cardiac phase during various stages in foreign manned spaceflight activities and the analysis of their possible mechanisms]

Electrocardiography (ECG) is still the only method for continuous medical observation during various stages of foreign manned spaceflight activities, and it also serves as an important item for medical monitoring in the project for manned spaceflight activities in our country. With electrocardiography, pulse or heart rate (one of the four life signs) and cardiac function can continuously be observed. Cardiac phase relative to ECG is a main index reflecting cardiac function. Understanding of the results of ECG and cardiac phase and their mechanisms during various stages of foreign manned spaceflight activities will be helpful in establishing emergency measures in the course of manned spaceflight activities in our country.

[Approximate entropy and its application in heart rate variability analysis]

Objective. To introduce approximate entropy in the analysis of heart rate variability, and to discuss the changes of the complexity of cardiovascular system during orthostatic standing posture. Method. ECG of 8 subjects were recorded during supine and orthostatic standing postures. Approximate entropy was used to analyze HRV. Result. Compared to supine before orthostatic standing posture, R-R intervals at 0-5 min, 5-10 min, 10-15 min and 15-20 min during orthostatic standing posture were decreased significantly, while approximate entropy at 0-5 min and 15-20 min decreased significantly. It showed that the complexity of cardiovascular system was decreased and the modulation of cardiovascular system changed. Conclusion. It is feasible that approximate entropy be used for heart rate variability analysis.

[The effect of fibrin sealant on dental pulp for pulp capping in experimental dogs]

OBJECTIVE

To investigate the pulp tissue reaction and reparative dentine formation of dog pulp capped with Fibrin Sealant (FS).

METHODS

The fibrin was from a tisseel Kit (Immuno AG, Vienna, Austria) consisting of solution A (freeze-dried human fibrinogen, factor XIII, Aprotinine) and solution B (thrombin powder, calcium chloride) with 0.02 ml from each for each tooth. The Ca(OH)2 paste (Calar, China) was served as the control. Forty nine cuspid, premolar and molar teeth in 4 adult dogs weighed 11-13 kg were used. Surgical anesthesia was obtained by muscle injection of 3% sodium pentobarbital (1 ml/kg). The pulp were exposed by using sterile high-speed rotary cutting instruments with water-cooling. The pulps were treated with 0.02 ml fibrin or Ca(OH)2 paste respectively. The cavity was filled with zine phosphate cement. The animals were killed at intervals of 1, 4, 6, 9 weeks after surgery and perfused with phosphate-buffered saline followed by 10% formalin in phosphate-buffered saline. The jaws were resected and the samples prepared by removing each experimental tooth in block, further fixing them by immersion in 10% formalin in phosphate-buffered saline. The specimen were processed for histologic examination. Serial sections (5 nm thick) were made, stained with hematoxylin and eosin, examined using a light microscope.

RESULTS

7 days after operation, the samples treated with the FS showed no hemorrhage and degeneration of pulp tissue and a small amount inflammatory cells near the wounds. The samples treated with Ca(OH)2 showed hemorrhage and degeneration (2/6) and a large amount inflammatory cells near the wounds. 28 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was nearly recovered. Dentin bridges were observed in 2 out of 6 cases treated with Ca(OH)2. 42 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was totally recovered. Dentin bridges were observed in 2 out of 7 cases of pulp treated with FS and four out of 6 cases treated with Ca(OH)2. 63 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was soundly resumed. The dentine bridge was observed in 4 out 6 cases of pulp treated with the FS and in all 6 cases treated with Ca(OH)2.

CONCLUSION

FS has no dentin inducing activity, but can enhance exposed pulp healing, so FS can be served as a promised pulp capping agent.

[Conformity of cancerous diagnosis of serum-fluorimetry under the influence of carotenoid fluorescence]

We observed that carotenoid had sensitization for fluorescence of porphyrin as cancerous diagnostic technology was applied in clinic by serum-fluorimetry. The Forster theory was used in order to analyse sensitized fluorescence between carotenoid and porphyrin in this paper. Transfer characteristic between energy donor and energy acceptor was calculated and discussed its influence on cancerous diagnosis.

[Change of pulmonary circulation in microgravity and simulated microgravity]

Fluid is transferred cephalad in microgravity and simulated microgravity, and the pulmonary circulation is the first to be affected. Blood and fluid contents in the lungs increase, but unevenly distributed among various zones of the lungs. Blood vessels in the lungs are filled and distend. Capillary changes have been observed in the animal model of simulated microgravity. Studies about the changes of regulative function of pulmonary circulation are relatively rare. Observations of the reactivity of pulmonary vessels may help to understand the mechanisms of the changes in pulmonary circulation during microgravity.

[Analysis and improvement consideration of the current human experimental models of humoral regulation in microgravity]

The main differences between physiological effects of microgravity in spaceflight and simulated microgravity on humans appeared in the circulation of the low pressure side, in humoral and electrolyte metabolism. For a further understanding of the physiological effects of microgravity, some improvement of the current human experimental models are needed. It is possible to choose more adequate models closer to the situation in microgravity through measuring cardiovascular parameters, fluid regulation and renal excretion variables under head-up tilt (HUT) plus lower body positive pressure condition, or under head-down tilt (HDT) plus upper body negative pressure in various angles and pressure levels.

Unsymmetrical response features of left and right brain to signals from left and right visual fields at different cognitive levels

OBJECTIVE

To study the response characteristics of left and right brain to signals from left (LVF) and right (RVF) visual fields during cognitive activity.

METHOD

ERPs at 9 locations to LVF and RVF signals were compared in 23 normal subjects in 3 task conditions: looking forward only (VC); making switch response to target signals (T) only (SR); making switch response to T differentially (DR).

RESULT

(1) Significant difference in ERPs was found between that induced by LVF and RVF signals on left brain especially at frontal location (F5), which appeared as slow negative deflection induced by T and NT from RVF in SR and DR; (2) Condition-dependent unsymmetrical features between left and right brain were found: the slow potential at F5 was significantly more negative in T and contralateral spatial relation (i. e., left brain for RVF) but more positive in NT and ipsilateral relation than that at F6.

CONCLUSION

Signals with psychological meaning in RVF might cause more psychological load as suggested by the results obtained in this study.

[EEG synchronization index spectrum: definition, calculation and the changes related to visual selective response]

OBJECTIVE

EEG synchronization is usually estimated in terms of coherence amplitude, but the estimation is with apparent uncertainty because of the poor resolution both in time and frequency. The purpose of this work is to surmount this problem.

METHOD

A new definition of EEG synchronization index spectrum [SynI(f)] was developed basing on the distribution characteristics of EEG coherence phase which was calculated by a tested algorithm with 1 s and 1 Hz resolution. The basic feature and its changes during visual selective responses were calculated in 25 normal subjects. EEG signals were recorded from 9 locations in two conditions: looking at the central LED only(VC) and making switch response to the target LED flash signals (T) differentially (DR): switch to left or right for Ts from left (LVF) or right (RVF) visual field, repectively but making no response to the non-target ones (NT).

RESULT

(1) The frequency dependency of SynI varied with brain location, e.g., SynI was higher in alpha range than others at frontal locations but the situation reversed at posterior locations. (2) The SynIs between midline and right brain locations were higher than that between mid line and left ones. (3) As compared with VC, SynI was increased in DR condition at central and posterior brain locations but not frontal ones, it happened mainly in 7-23 Hz at central locations but in 1-4 Hz at posterior ones. (4) The augmentation of SynI in DR was greater for T than for NT signals.

CONCLUSION

The results indicated that the SynI(f) was meaningful for studying the frequency-spatial feature of EEG synchronization change among brain locations related to cognitive activities.

[The progress in research on the mechanisms of the effects of blood volume reduction on orthostatic tolerance after microgravity or simulated microgravity]

Orthostatic intolerance commonly occurs after spaceflight, but its mechanisms remain to be clarified. It is believed that the reduction of blood volume might be one of the important factors. So the current countermeasures against orthostatic intolerance are aimed to control the changes of blood volume. The main differences between physiological effects of microgravity and simulated microgravity on humans appear in the circulation of the low pressure side and in humoral and electrolyte metabolism. Reflexes elicited from the low pressure side are very important for regulation of the extracellular fluids. The authors postulated that for a further understanding of mechanisms of orthostatic intolerance after spaceflight and to establish appropriate countermeasures against orthostatic intolerance, it is important to study the course of changes of the circulation in the low pressure side and the reflexes thus elicited with more appropriate method of simulation.

[The effects of the complex of rhBMP2 and fibrin sealant on dental pulp]

OBJECTIVE

To investigate the reparative dentine formation induced by the complex of recombinant human bone morphogenetic protein 2 (rhBMP2) and fibrin sealant (FS) in dog tooth.

METHODS

Freshly exposed molars, premolars and cuspids were treated with the complex of rhBMP2/FS, rhBMP2 and Ca(OH)(2) paste which served as control.

RESULTS

The wound healing of exposed pulp treated with FS seemed to be better than that without FS. Dentine bridge formation was observed in pulp treated with the complex at 7 days, with rhBMP2, Ca(OH)(2) at 28 days. At 63 days after operation, the cases of tubular dentine bridge formation of the pulp treated with the complex were more than that of pulp treated with rhBMP2.

CONCLUSION

The synergistic effects of FS and the complex rhBMP2 exist and can be used as bioactive pulp capping agent.

[The progress in research on changes of central venous pressure under simulated weightlessness and microgravity]

One of the most profound circulatory changes that occur in man during exposure to microgravity is a cephalad redistribution of fluid. Central venous pressure (CVP) is not only an important standard for determining the cephalad redistribution of fluid but also the unique valuable means for measuring continuously cardiac filling pressure under simulated weightlessness (SW) and microgravity, and has a relationship with neurohumoral [correction of nerohumoral] regulation. With the development of manned spaceflight, the researches in space suggested that CVP did not increase, which is directly contradictory to the previous results under SW. This paper mainly discusses the changes of CVP and the effects of countermeasures on CVP under SW and microgravity, and the mechanisms of decreased CVP under microgravity. It is postulated that more suitable SW models, more studies about the area of low pressure including especially pulmonary circulation, and comprehensive studies in multiple systems are needed.

[Character identification of 12 kinds of pilose antler medicinal materials]

In this paper, commercial medicinal materials of 12 kinds of pilose antler, Cervus nippon, C. elaphus, C. albirostris, C. unicolor, C. eldihainanus, C. timorensis C. porinus, Dama dama, Rangifer farandus, Alces alces, Elaphurus davidianus, Capreolus capreolus were compared and identified. A key and simple character illustration were listed.

[Effect of extremely low frequency magnetic field on brain response to selective mental arithmetic under simulated weightlessness]

Objective. To study effects of extremely low frequency magnetic field (ELMF) on brain function state during weightlessness. Method. The brain event-related potentials (ERPs) during a selective mental arithmetic task were compared in 40 normal subjects (20-25 yrs) before and after ELMF (5 Hz) stimulation during simulated weightlessness (head down tilt -10 degrees, HDT). Result. The amplitude of slow positive potentials which were supposed to be related to the mental arithmetic activity decreased significantly especially in 100 min after HDT, but it did not decrease significantly after ELMF stimulation. Conclusion. ELMF stimulation may improve the brain function state during simulated weightlessness.

Extract of Solanum muricatum (Pepino/CSG) inhibits tumor growth by inducing apoptosis

BACKGROUND

Apoptosis, or programmed cell death, is characterized by certain distinct morphological and biochemical features. Most chemotherapeutic drugs exert their anti-tumor effects by inducing apoptosis. Therefore, an effective compound inducing apoptosis appears to be a relevant strategy to suppress various human tumors. In a search for tumor inhibitors from various kinds of plants, we found that extracts from Solanum muricatum (CSG) can inhibit tumor growth both in vivo and in vitro by inducing apoptosis.

MATERIALS AND METHODS

A lyophilized aqueous fraction extracted from Solanum muricatum (CSG4) was used in this study. The human cell lines tested include: prostate (PC3, DU145), stomach (MKN45), liver (QGY-7721, SK-HEP-1), breast (MDA-MB-435), ovarian (OVCAR), colon (HT29) and lung (NCI-H209) cancer cells; NHP (prostate), HUVEC (umbilical vein endothelial cell), and WI-38 (lung diploid fibroblasts) normal cells. The cell survival was determined by either Cell Titer MTS cell proliferation kit or trypan blue dye exclusion assay. The apoptosis was analyzed by (a) apoptotic morphology by light microscopy; (b) DNA ladder formation; (c) PARP cleavage assay.

RESULTS

a) CSG possesses selective cytotoxic activity against all the tumor cell lines being tested. The LD50 value is 561-825 micrograms/ml. b) CSG showed a much lower cytotoxicity to NHP, HUVEC and WI-38 normal cell lines with LD50 value being 2.8-3.2 mg/ml, which is 3-6 fold higher than on tumor cells. c) The in vivo study demonstrated that injection of CSG (100 micrograms) directly into tumor mass can reduce the tumor volume dramatically in nude mice inoculated with MKN45 gastric cancer cells. d) CSG-mediated tumor growth inhibition is through induction of apoptotic cell death, as manifested by (a) typical apoptotic morphology; (b) DNA ladder formation; and (c) PARP cleavage assay.

CONCLUSION

Taken together, the present study suggests, for the first time, that CSG may represent promising new chemical entity which preferentially targets various tumor cells by triggering apoptosis.

[Intercellular adhesion molecule-1 expression in experimental liver fibrosis]

OBJECTIVE

To explore the role of intercellular adhesion molecule-1 (ICAM-1) in experimental liver fibrosis.

METHODS

Experimental liver fibrosis models of rats were induced by high fat diet, low fat diet plus ethanol, high fat diet plus ethanol, and carbon tetrachloride subcutaneous injection respectively. At sacrifice, liver pathologic changes were studied and ICAM-1 expression was evaluated with immunohistochemistry by using a monoclonal antibody.

RESULTS

ICAM-1 expression was observed in the hepatocellular membrane; ICAM-1 positive hepatocytes were localized in zones of portal tract with focal necrosis and inflammatory damage. Staining for ICAM-1 was associated with the degree of liver inflammation and fibrosis. In the different models, the intensity of ICAM-1 expression was different; It ranged in an increasing order from high fat diet, low fat diet plus ethanol, high fat diet plus ethanol, and carbon tetrachloride model. The strongest reactivity for ICAM-1 was seen in carbon tetrachloride model (P < 0.05), the difference was significant as compared with the other models. However, there was no significant difference among the three other models (P > 0.05).

CONCLUSION

Upregulation of ICAM-1 expression in experimental liver fibrosis may be related with liver fibrogenesis.

Cathepsin B on invasion and metastasis of gastric carcinoma

OBJECTIVE

To investigate the expression of cathepsin B (CB) in human gastric carcinoma tissue.

METHODS

The expression of CB in human gastric tissue was studied by using monospecific polyclonal rabbit antibody raised against human liver CB for immunohistochemistry, and full length cDNA of CB for in situ hybridization and dot blot.

RESULTS

CB overexpression in gastric carcinoma was found when compared with non-neoplastic gastric tissue at both mRNA and protein levels. Diffuse cytoplasmic CB staining of mRNA and protein were identified in malignant cells of 53.3% and 69.1% of gastric adenocarcinoma respectively. The increased staining of CB in malignant cells was associated with the depth of the invasiveness and growth pattern as well as metastasis of lymph nodes, but not with the histological classification. It was also found that there were the expression of CB in stromal cells of the tumor and the expression localized mainly in the endothelial cells of the microvessels which correlated with angiogenesis.

CONCLUSION

These results indicate that the expression of CB in gastric carcinoma is related to tumor progression, and leads to development of the invasive phenotype.

Temporal and spatial features of slow positive potential related to visual selective response during head-down-tilt

The temporal and spatial features of visual ERP changes during 2 hour HDT (-10 degrees) were compared with that during HUT (+20 degrees) in 15 normal subjects. The stimuli consisted of two color LED flashes appeared randomly in left (LVF) or right (RVF) visual field with the same probability. The subjects were asked to make switch response to target signals (T) differentially: switching to left for T in LVF and to right for T in RVF, and making no response to non-target signals (N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on the scalp. Mean amplitude of the ERPs in the period 0.30-0.55 s were taken as the amplitude of slow positive potential (P400). The results obtained were: (1) The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; (2) spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and were more significant at posterior and central brain regions than those from frontal locations. These data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.

[Changes of brain potentials related to selective mental arithmetic during simulated weightlessness]

To study the effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) during a selective mental arithmetic task were compared between head down tilt (HDT) and head up tilt (HUT) in 15 normal subjects. The results were: target (T) flash signals induced significant slow positive potentials and they decreased significantly in amplitude especially during HDT as compared with that during HUT. The data provide new evidence indicating that the ability of brain response declined during simulated weightlessness.

Determining the degree of chaos from analysis of ISI time series in the nervous system: a comparison between correlation dimension and nonlinear forecasting methods

Two different chaotic time series analysis methods--the correlation dimension and nonlinear forecasting--are introduced and then used to process the interspike intervals (ISI) of the action potential trains propagated along a single nerve fiber of the anesthetized rat. From the results, the conclusion is drawn that compared with the correlation dimension, nonlinear forecasting is more efficient and robust for chaotic ISI time series analysis in a noisy environment. Moreover, the evolution of the correlation coefficient curves calculated from nonlinear forecasting can qualitatively give a better reflection of the unpredictability of the system's future behavior and is in good agreement with the values of the largest Lyapunov exponent that quantitatively measures the degree of chaos.

Dynamic change of ERPs related to selective attention to signals from left and right visual field during head-down tilt

To study further the effect of head-down tilt (HDT) on slow positive potential in the event-related potentials (ERPs), the temporal and spatial features of visual ERPs changes during 2 hour HDT (-10 degrees) were compared with that during HUT (+20 degrees) in 15 normal subjects. The stimuli were consisted of two color LED flashes appeared randomly in left or right visual field (LVF or RVF) with same probability. The subjects were asked to make switch response to target signals (T) differentially: switching to left for T in LVF and to right for T in RVF, ignoring non-target signals(N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on scalp. The mean value of the ERPs in the period from 0.32-0.55 s was taken as the amplitude of slow positive potential(P400). The main results were as follows. 1) The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; 2) spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and was more significant at posterior and central brain regions than that on frontal locations. As that the positive potential probably reflects the active inhibition activity in the brain during attention process, these data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.

[Electro-acupuncture effects on experimental spinal cord injury of the cat as evaluated by acid phosphatase detection]

The spinal cords of adult cats were injured at about L1 level by using Allen's method and the animals were divided randomly into 2 groups: a) electro-acupuncture treatment group and b) control group. The acid phosphatase (ACP) was detected at 3 and 7 days after spinal cord injury. The more ACP positive labelings were found in the treatment group than in the control group at both 3 (P < 0.05) and 7 days (P < 0.01) after injury. The results suggested that electro-acupuncture could increase the concentration of ACP of the injured spinal cord and the increased ACP concentration could make worse to the injured spinal cord at early time and improve regeneration during recovery period.

Studies on the relationship between changes in radiographic bone height and probing attachment

The aim of this investigation was to determine the relationship between loss of radiographic crestal bone height and probing attachment loss. As part of this aim, we are introducing a new method for determination of a threshold for significant probing attachment loss which takes into account the error contributed by alteration in tissue tone. 57 adults with established periodontitis were selected. Radiographs were taken using the Rinn alignment system. Crestal change was determined from bone height measurements on digitized images of pairs of radiographs using the "side-by-side" technique of analysis developed recently by us. Probing attachment loss was measured using the Florida electronic probe system. Radiographic and probing measurements were made at baseline and after 1 year. No treatment was given during this period. A direct and significant relationship was observed between radiographic bone loss and probing attachment loss on a site basis (p = 0.0001, r2 = 0.018) and between subject means (p = 0.0014, r2 = 0.16). Radiographic and probing attachment change at all categories of sites, dichotomously classified as to not changing or loosing indicated 13% of sites were loosing by measurement of radiographic change and 9.6% were loosing by measurement of attachment change. Concordance in radiographic and attachment level change was found in 82% of sites examined. The relative diagnostic import of change in probing attachment or change in radiographic bone height requires treatment outcome studies based on use of diagnostic information of the 2 measuring techniques used singly and in combination.

Regulation of C-myc protooncogene expression in osteoblastic cells by arachidonic acid metabolites: relationship to proliferation

Prostaglandin E2 and leukotriene B4 are metabolites of arachidonic acid with well-characterized effects on osteoblastic cells. Prostaglandin E2 has been shown to be a potent bone-resorbing agent and to stimulate as well as inhibit osteoblastic cell proliferation. Leukotriene B4 has also been demonstrated to stimulate or inhibit osteoblastic cell proliferation, depending on the cell type tested. In the present study, the potential relationship of the effects of prostaglandin E2 and leukotriene B4 on osteoblastic cell proliferation to c-myc protooncogene expression was investigated. Prostaglandin E2 has been shown previously to inhibit normal rat osteoblastic cell proliferation. The present studies show that prostaglandin E2 at 10(-6) M decreased c-myc expression in these cells. In the human osteoblastic osteosarcoma cell line, G292, prostaglandin E2 increased c-myc expression and inhibited proliferation. In contrast, epidermal growth factor increased DNA synthesis as well as c-myc expression. Prostaglandin E2 also inhibited proliferation of another human osteoblastic osteosarcoma cell line, Saos-2, but it did not produce any changes in c-myc expression. In these cells, epidermal growth factor did not affect either DNA synthesis or c-myc expression. Leukotriene B4 did not show any effects on c-myc expression in any of the osteoblastic cells tested.

Effects of leukotrienes on osteoblastic cell proliferation

Leukotriene B4 (LTB4) is an arachidonic acid lipoxygenase metabolite with well-characterized effects on leukocytes. LTB4 has been implicated in acute inflammatory reactions and in bone resorption. In the present study, the effect of LTB4 on osteoblastic cells was examined. LTB4 inhibited cell proliferation in normal osteoblastic rat calvaria cells in a dose-dependent manner and had biphasic effects in the human osteoblast-like osteosarcoma cell lines Saos-2 and G292. Indomethacin did not modulate the nature of these LTB4 effects in any of the cells. However, it potentiated the high LTB4 dose effects in normal cells and G292 cells. AA861, an inhibitor of lipoxygenase, did not modulate the LTB4 effects in these two cell lines. These results suggest that LTB4 is involved in the regulation of osteoblastic cell proliferation and may interact with prostaglandins to modulate these effects.