[Analysis of work-related musculoskeletal disorders among automobile manufacturing logistics workers in Guangzhou]

Objective: To investigate the occurrence of work-related musculoskeletal disorders (WMSDs) in logistics workers of automobile manufacturing enterprises in Guangzhou, and explore their potential categories and influencing factors, so as to provide basis for the prevention and control of WMSDs in logistics workers of automobile manufacturing enterprises. Methods: From April to May 2020, a convenient sampling method was adopted to select 1442 logistics workers in 2 automobile manufacturing enterprises in Guangzhou as the research objects. The incidence of WMSDs among them was investigated by using the Nordic Musculoskeletal Disorders Questionnaire, and the incidence pattern of WMSDs among the subjects was analyzed by the method of potential category analysis. Chi-square test and multiple logistic regression model were used to analyze the influencing factors of the disease. Results: The total prevalence of WMSDs was 42.9% (619/1442). The three parts with high prevalence of WMSDs were neck (23.5%, 339/1442), shoulder (21.3%, 307/1442) and lower back (19.1%, 275/1442). 69.0% (427/619) of the patients showed simultaneous disease in two or more sites. The subjects were divided into four latent groups by the analysis of latent categories: the group with multiple body parts (4.51%), the group with very low or no disease (70.39%), the group with shoulder and neck and upper back (11.37%), and the group with limbs and lower back (13.73%). Multivariate logistic regression showed that compared with the "very low or no disease group", the risk factors of multiple body parts of automotive logistics workers suffering from WMSDs mainly included: Working posture uncomfortable (OR=3.10, 95%CI: 1.44~6.70, P=0.004), often bend and turn (OR=2.36, 95%CI: 1.05~5.29, P=0.037), bend your knees homework for a long time (OR=2.29, 95%CI: 1.17~4.47, P=0.015) ; Working posture uncomfortable (OR=2.26, 95%CI: 1.51~3.38, P<0.001), bending the neck (OR=1.68, 95%CI: 1.03~2.74, P=0.036), neck minister time keep the same position (OR=1.81, 95%CI: 1.22~2.67, P= 0.003) It is a risk factor for shoulder, neck and upper back WMSDs; Risk factors for limb-lower back WMSDs include: Length > 10 years (OR=2.16, 95%CI: 1.24~3.78, P<0.001), the working position uncomfortable (OR=2.38, 95%CI: 1.63~3.48, P<0.001), bending the neck (OR=1.66, 95%CI: 1.03~2.68, P=0.039) . Conclusion: The prevalence rate of WMSDs among logistics workers in automobile manufacturing enterprises is high, which has obvious characteristics of classification and comorbis, and is closely related to individual characteristics such as sufficient rest time and working posture of workers.

The Diagnostic Value of Serum ST8SIA6-AS1 as Biomarker in Hepatocellular Carcinoma

BACKGROUND

Long noncoding RNA (lncRNA) is a promising serum biomarker in cancer diagnosis. However, literature on the diagnostic value of the lncRNA for hepatocellular carcinoma (HCC) is scant.

METHODS

The expression of ST8SIA6-AS1 in serum and HCC cell lines was detected by real-time PCR (RT-PCR). We then analyzed the relationship between clinicopathological characteristics and serum ST8SIA6-AS1 expression. In addition, we performed the receiver operating characteristic (ROC) curve and area under curve (AUC) analyses to determine the diagnostic ability of serum ST8SIA6-AS1.

RESULTS

Our data demonstrated an up-regulation of ST8SIA6-AS1 in 77 HCC patients and HCC cell lines. Besides, clinicopathological analysis revealed that ST8SIA6-AS1 corresponds with tumor stages and metastasis, thus might be used for monitoring the HCC progress. Importantly, the ROC analysis demonstrated that ST8SIA6-AS1 yields a superior diagnostic ability. Compared with α-fetoprotein (AFP) alone, a combination of ST8SIA6-AS1 and AFP may achieve more reliable diagnostic results.

CONCLUSIONS

Together, our results demonstrate that serum ST8SIA6-AS1 is a promising serum diagnostic bio-marker for HCC.

Comparative Transcriptomics and Proteomics of Atractylodes lancea in Response to Endophytic Fungus Gilmaniella sp. AL12 Reveals Regulation in Plant Metabolism

The fungal endophyte Gilmaniella sp. AL12 can establish a beneficial association with the medicinal herb Atractylodes lancea, and improve plant growth and sesquiterpenoids accumulation, which is termed “double promotion.” Our previous studies have uncovered the underling primary mechanism based on some physiological evidences. However, a global understanding of gene or protein expression regulation in primary and secondary metabolism and related regulatory processes is still lacking. In this study, we employed transcriptomics and proteomics of Gilmaniella sp. AL12-inoculated and Gilmaniella sp. AL12-free plants to study the impact of endophyte inoculation at the transcriptional and translational levels. The results showed that plant genes involved in plant immunity and signaling were suppressed, similar to the plant response caused by some endophytic fungi and biotroph pathogen. The downregulated plant immunity may contribute to plant-endophyte beneficial interaction. Additionally, genes and proteins related to primary metabolism (carbon fixation, carbohydrate metabolism, and energy metabolism) tended to be upregulated after Gilmaniella sp. AL12 inoculation, which was consistent with our previous physiological evidences. And, Gilmaniella sp. AL12 upregulated genes involved in terpene skeleton biosynthesis, and upregulated genes annotated as β-farnesene synthase and β-caryophyllene synthase. Based on the above results, we proposed that endophyte-plant associations may improve production (biomass and sesquiterpenoids accumulation) by increasing the source (photosynthesis), expanding the sink (glycolysis and tricarboxylic acid cycle), and enhancing the metabolic flux (sesquiterpenoids biosynthesis pathway) in A. lancea. And, this study will help to further clarify plant-endophyte interactions.

[Study on determination of ethylal in workplace air by gas chromatography]

Objective: A solvent desorption-gas chromatography method for determination of ethylal in workplace air has been established. Methods: Ethylal in workplace air was collected by activated carbon tube and desorbed with carbon disulfide, and the desorption solutions were analysed by capillary column GC with FID detector. Results: The method presented a good linearity in the range of 0.87~34 800.00 mg/L of ethylal in the standard solution, with the correlation coefficient being r=0.999 7. The limit of detection and the limit of quantification of this method were respectively 0.20 mg/L and 0.80 mg/L, and the minimum detectable concentration and the minimum quantification concentration of this method were respectively 0.17 mg/m(3) and 0.60 mg/m(3) per 1.50 L of air.The within-run precision of the method was 2.93%-6.20%, and the between-run precision 3.67%-6.44%. The desorption efficiency between 94.22%-97.27%. Ethylal in activated carbon tube could be kept at least 7 days at room temperature without significant loss. Conclusion: The method could be used for determination of ethylal in workplace air.

Role of the JAK-STAT pathway in protection of hydrogen peroxide preconditioning against apoptosis induced by oxidative stress in PC12 cells

The aim of this study was to investigate the role of JAK-STAT pathway in the cytoprotection afforded by preconditioning with H(2)O(2). It was shown that (1) Preconditioning with 100 micromol/L H(2)O(2) can markedly protect PC12 cells against apoptosis and cytotoxicity induced by 300 micromol/L H(2)O(2); (2) The expression and tyrosine phosphorylation of JAK2, not JAK1 were rapidly increased at 5 min after H(2)O(2) preconditioning; (3) The expression of STAT1 and STAT3 were significantly increased at 15 min after H(2)O(2) preconditioning, and the pTyr-STAT1 and pTyr-STAT3 were markedly increased at 60 min after H(2)O(2) preconditioning; (4) Pretreatment with the JAK inhibitor AG-490 (10 micromol/L) 20 min before H(2)O(2) preconditioning blocked not only the activation of JAK2, STAT1 and STAT3, but also the cytoprotection of H(2)O(2) preconditioning against apoptosis and cytotoxicity induced by oxidative stress. These findings suggested that preconditioning with H(2)O(2) activated the JAK-STAT pathway that played an important role in the cytoprotection induced by H(2)O(2) preconditioning.

Curcumin protects PC12 cells against 1-methyl-4-phenylpyridinium ion-induced apoptosis by bcl-2-mitochondria-ROS-iNOS pathway

The aim of present study is to explore the cytoprotection of curcumin against 1-methyl-4-phenylpridinium ions (MPP(+))-induced apoptosis and the molecular mechanisms underlying in PC12 cells. Our findings indicated that MPP(+) significantly reduced the cell viability and induced apoptosis of PC12 cells. Curcumin protected PC12 cells against MPP(+)-induced cytotoxicity and apoptosis not only by inducing overexpression of Bcl-2, but also reducing the loss of mitochondrial membrane potential (MMP), an increase in intracellular reactive oxygen species (ROS) and overexpression of inducible nitric oxide synthase (iNOS). The selective iNOS inhibitor AG partly blocked MPP(+)-induced apoptosis of PC12 cells. The results of present study suggested that the cytoprotective effects of curcumin might be mediated, at least in part, by the Bcl-2-mitochondria-ROS-iNOS pathway. Because of its non-toxic property, curcumin could be further developed to treat the neurodegenerative diseases which are associated with oxidative stress, such as Parkinson's disease (PD).

Assessment of fetal status in multiple gestation pregnancies using interphase FISH

The use of fluorescence in situ hybridization (FISH) for women with multiple gestation pregnancies has been evaluated. Women were referred for chromosome analysis because of advanced maternal age, abnormal ultrasound findings or a positive family history and/or prior to fetal reduction. FISH was successfully applied to all specimens obtained by amniocentesis or chorionic villus sampling (CVS). Based on FISH results, fetal-fetal contamination of specimens following CVS was 11.5% in twin pregnancies and 16% in triplet or higher multiples. FISH detected trisomy 21 in three cases with no false negatives or positives. Whereas FISH may provide rapid and useful assessment of fetal status in decision-making regarding fetal reduction, the present study also highlighted the obstetrical difficulty of ensuring a sample representative of each fetus following CVS in addition to the possibility of not identifying clinically significant chromosome aberrations using currently available FISH probes.

The clinical application of interphase FISH in prenatal diagnosis

Fluorescence in situ hybridization (FISH) for five chromosomes (13, 18, 21, X and Y) detected 87 of 107 (81%) of the chromosome aberrations identified by conventional chromosome analysis applied to fetal interphase cells obtained by chorionic villus sampling or amniocentesis. The choice of FISH was solely determined by prospective parents after formal genetic counselling concerning the advantages and disadvantages of FISH analysis. Excluding known familial chromosome aberrations, if FISH analysis revealed normal signals, there was an overall residual risk of 1 in 149 for an undetectable chromosome aberration. This risk varied according to the indication for prenatal diagnosis: 1 in 177 for women of advanced maternal age; 1 in 60 for women at increased risk for Down syndrome based on maternal serum screening; and, 1 in 43 for women whose ultrasound examination revealed fetal anomalies. There were 20 cases of discordance between the FISH results and standard karyotype analysis: four were the outcome of a failure to apply the appropriate FISH probe; 16 were not detectable by the available FISH probes. Of these 16, nine were chromosome abnormalities with clinical significance and seven were familial. If FISH is to become a standard part of prenatal genetic diagnosis, genetic counselling that is sensitive to patient health needs must be based on accurate information about the biological and obstetrical implications of the results of FISH analysis.

[Effects of 17 beta-estradiol on delayed rectifier potassium channels in hippocampal pyramidal neurons of the rat]

In the present study, both cell-attached and inside-out patch-clamp techniques were used to detect the effects of 17 beta-estradiol (E2) on 42 pS delayed rectifier potassium channels in acutely dissociated hippocampal neurons of new-born SD rats. The results indicated that after application of 1.0 and 10.0 nmol/L E2, the open probabilities of K+ channels were decreased from (67.4 +/- 18.2)% to (41.2 +/- 12.5)% and from (56.3 +/- 15.8)% to (13.2 +/- 12.6)% respectively, the open frequencies were reduced from (43.40 +/- 6.7) Hz to (27.68 +/- 9.1) Hz and from (38.19 +/- 10.1) Hz to (15.79 +/- 3.5) Hz respectively. Meanwhile, there was a shortening of the mean open time and a lenghtening of the mean close time of the channels. The above results suggest that E2 has suppressive effects on the activities of the channels, which might be exerted through a direct action on the cellular membrane.

Factors associated with maternal cell contamination in amniocentesis samples as evaluated by fluorescent in situ hybridization

OBJECTIVE

To determine which patient- and procedure-related factors contribute to maternal cell contamination in uncultured amniocentesis fluid.

METHODS

One hundred thirty amniotic fluid (AF) samples were obtained by three operator groups: maternal-fetal medicine faculty (n=50), general obstetrician gynecologists (n=50), and obstetrics and gynecology residents supervised by maternal-fetal medicine faculty (n=30). These groups were designated "most," "intermediate," and "least experience," respectively. Study variables were recorded at the time of the procedure. Amniotic fluid cells from male fetuses underwent fluorescent in situ hybridization. Maternal cell contamination was calculated by analyzing 100 cells and determining the number of XX and XY cells. A control system was created to validate the methods used for AF processing and cell counting.

RESULTS

Median maternal cell contamination was 2.0%. Maternal cell contamination did not vary with body mass index (r=-.13, P=.14), gestational age (r=.08, P=.35), or placental location (P=.55). Maternal cell contamination was significantly elevated with placental penetration (6.0% compared with 1.0%, P < .001), two passes (27.5% compared with 2.0%, P=.002), blood-tinged fluid color (14.0% compared with 2.0%, P < .001), and operator inexperience ("intermediate experience" compared with "most experience," 4.5% compared with 1.0%, P=.026). Maternal cell contamination did not differ between the "most experience" and "least experience" groups (1.0% compared with 2.0%, not significant). Concordance between detected and actual maternal cell contamination in the control system was extremely high (concordance coefficient=0.98, P=.008), confirming the validity of the techniques used.

CONCLUSION

Our techniques of cell counting and maternal cell contamination calculation are accurate. Maternal cell contamination is increased with placental penetration, two passes, and operator inexperience. However, with expert supervision, inexperienced physicians can perform amniocentesis without an increase in maternal cell contamination.

Hybridization of chromosome 18 alpha-satellite DNA probe to chromosome 22

Fluorescence in situ hybridization (FISH) of uncultured chorionic villus diploid cells with a chromosome 18 alpha-satellite DNA probe (D18Z1) revealed a third small signal in addition to two large signals. FISH analysis of diploid metaphase cells from cultured chorionic villus cells and from maternal lymphocytes revealed that the third signal resulted from hybridization to the centromere of chromosome 22. This is the first report of a variant involving D18Z1 detected by FISH and of hybridization of alpha-satellite from a sub-metacentric chromosome to the centromere of an acrocentric chromosome. We propose that this inherited variant resulted from insertion of chromosome 18 specific alpha-satellite DNA sequences into the centromeric region of chromosome 22.

Unusual degradation of alpha-beta complexes in Xenopus oocytes by beta-subunits of Xenopus gastric H-K-ATPase

The catalytic alpha-subunit of oligomeric P-type ATPases such as Na-K-ATPase and H-K-ATPase requires association with a beta-subunit after synthesis in the endoplasmic reticulum (ER) to become stably expressed and functionally active. In this study, we have expressed the beta-subunit of Xenopus gastric H-K-ATPase (betaHK) in Xenopus oocytes together with alpha-subunits of H-K-ATPase (alphaHK) or Na-K-ATPase (alphaNK) and have followed the biosynthesis, assembly, and cell surface expression of functional pumps. Immunoprecipitations of Xenopus betaHK from metabolically labeled oocytes show that it is well expressed and, when synthesized without alpha-subunits, can leave the ER and become fully glycosylated. Xenopus betaHK can associate with both coexpressed alphaHK and alphaNK, but the alpha-beta complexes formed are degraded rapidly in or close to the ER and do not produce functional pumps at the cell surface as assessed by 86Rb uptake. A possible explanation of these results is that Xenopus betaHK may contain a tissue-specific signal that is important in the formation or correct targeting of functional alpha-beta complexes in the stomach but that cannot be recognized in Xenopus oocytes and in consequence leads to cellular degradation of the alpha-beta complexes in this experimental system.

[Changes of K+ channel current in cerebellar cortical neuron of apoptosis induced with H2O2]

The neurons dissociated from the cerebellar cortex of neonatal SD rat were cultured, while the growth of non-neuron cells were suppressed by Ara-c. Apoptosis of the neurons were induced with H2O2. The changes of Ik were studied during apoptosis using the patch clamp technique in cell-attached configurations. The results are as follows: (1) the Ik amplitudes of the neurons were lower than that of normal at various corresponding clamp voltages; (2) the conductances, mean open time, open probability, long and short opening time constants were all lower, as compared with normal neurons. All these results indicate that the activities of K+ channels on cerebellar neurons decrease during apoptosis.

[Effect of pregnenolone sulfate on delayed rectifier K+ channel in pyramidial neuron of cerebral cortex]

Recent studies have shown that endogenous brain metabolites of steroids may exert important nongenomic modulatory effects on neuronal mechanisms. In this work the effect of pregnenolone sulfate (PS) on delayed rectifier K+ channel (IK) was studied in acutely dissociated rat cerebral cortical pyramidial neurons by means of cell-attached and inside-out patch clamp techniques. The open probability and mean open time of the IK channels were increased by PS in a concentration-dependent manner over the range of 30-100 mumol/L. but without changing the IK amplitude.

[ATP-activated single ion channel and its properties in cerebral cortical neurons of neonatal rat]

In the present study, single channel currents were recorded from single neurons dissociated from the cerebral cortex of neonatal SD rat by the cell-attached and inside- out modes of patch clamp technique. ATP-activated channels with a conductance of 32 pS were often recorded and permeable to Na+, K+ and Cs+, but not to Cl-. Most of open time distribution histograms were fitted by two exponential components and few by one, whereas closed time distribution histograms were fitted by two exponential components. Both mean open time and open probability were independent of membrane potential, but the latter increased with increasing ATP concentration. The channel activity was recorded only in the presence of pipette solution containing ATP, and its conductance and open probability were not affected by ACh N-receptor antagonist hexamethonium and mecamylamine. It is suggested that ATP-activated ion channels probably exist in the cerebral cortical neurons of neonatal rat.

Dopamine-induced ionic currents in acutely dissociated rat neurons of CNS

AIM

To determine whether or not the dopamine (DA) can induce ionic current in single neuron acutely dissociated from different central areas including striatum, ventral tegmental area (VTA), substantia nigra pars compacta (SNC) and hippocampal CA1 area.

METHODS

Using a new patch-clamp whole-cell recording technic, namely nystatin-perforated whole-cell configuration under voltage-clamp mode.

RESULTS

In 36 single neurons isolated from the striatum and VTA, DA 10-1000 mumol.L-1 was quite diverse to elicit ionic current responses. In 19 SNC neurons, 5 neurons (26%) response to 1 mmol.L-1 DA represented as a small outward current (11.3 +/- 2.4 pA) at a holding potential (V(H)) of -20 mV. In 25 of 69 (36%) examined hippocampal CA1 pyramidal neurons, however, application of DA induced 3 types of current responses: outward current (8 neurons) accompanied with an increase of membrane conductance, slow inward current (5 neurons) with an decrease of membrane conductance and outward-following inward current (12 neurons) at a V(H) of -20 mV. The concentration-response relationship of DA-induced currents showed the typical sigmoid shape with the threshold dose, being the maximum response dose are 3 mumol.L-1 and 1 mmol.L-1 respectively. The current-voltage (I-V) relationship of DA-induced responses did not show any voltage-dependent manner and the reversal potential (E(DA)) was close to the equilibrium potential of potassium (E(K)) calculated with the Nernst equation. TEA 5 mol.L-1 effectively inhibited the DA-induced response.

CONCLUSION

These results suggest that DA-induced outward current is carried by K+ in single hippocampal CA1 pyramidal neuron.

[Single channel properties of NMDA receptors in cortical neurons]

The cell-attached and inside-out configurations of the patch-clamp techniques were used to investigate single channel properties of NMDA receptors in cultured intact neurons mechanically isolated from rat cereberal cortex. Recordings were made in Mg(2+)-free solutions. A channel, with a conductance of 35 pS was studied in detail with either NMDA or L-aspartate in the patch pipette. NMDA channels were permeable to Na+ K+, but not to Cl-, the mean open times and open probabilities of these channels were decreased with increasing hyperpolarization. Distributions for the open times, closed times and burst durations required two-component fits. Channel openings were suppressed by APV. When Mg2+ was included in the pipette, the mean open times were significantly diminished in a concentration- and voltage-dependent manner. Decreasing the bath temperature prolonged channel open times and decreased current amplitudes. The results indicate that there is an intrinsic voltage dependence of NMDA channel kinetics in the intact neurons, suggesting that the normal function of the NMDA channel may be dependent on some intracellular biochemical processes.

[Study on the collagen of the different region of disc and different sigmental disc]

With the method of the collagen decomposition producting special hyoroxyprolines (HYP), the collagens of the different region of discs and different segmental discs were studied. The results were as follow: The fibrous annulus had a higher collagen content than did the nucleus pulposus (P < 0.001). In fibrous annulus, the inner region had a lower collagen content was found at the postolateral part of the fibrous annulus (P < 0.05), especially at the poster-lateral inner zone (P < 0.001). The local low-collagen content at the particular location may be one of the factors, which was clinically susceptible to a disc herniation at the part. An increasing graduation of collagen content was found from thoracic disc12 to lumbar disc 5. But, there was no statistically significant difference (P > 0.05).

[Spectrum analysis of cat si neurone discharges]

Spontaneous firing and the discharges evoked by A- and/or C-fiber inputs (A-ED, C-ED, AC-ED) of saphenous nerve were recorded in the somatosensory cortical (SI) neurons (n = 128) of the cats anesthetized with chloralose and paralysed by gallamine. Normalized power spectrum density function (NPSDF) was used to analyse the neuron discharges. The results showed that 1) all the NPSDFs for the spontaneous discharges were single-peak with a peak frequency of 3.91 +/- 1.63 Hz (spontaneous rhythm) and a peak value of 0.0154 +/- 0.0045; 2) the NPSDFs of A-ED showed a single peak (peak value 0.021 +/- 0.0054) and an overlapped double-peak (with spontaneous discharge) or a separate multi-peak (without spontaneous discharge); 3) the NPSDFs of C-ED showed a single peak (peak value 0.020 +/- 0.007) or a separate double-peak; 4) the NPSDFs of AC-ED have two patterns: a single peak (peak value 0.023 +/- 0.004) and an overlapped multi-peak. It is suggested that A-fiber input can potentiate the rhythms of the spontaneous discharge and induce specific rhythm; that C-fiber input can potentiate the spontaneous rhythm and induce characteristic C-rhythm. It is also observed that both spontaneous rhythm and evoked rhythm affect each other; that the evoked rhythms by A-fiber and C-fiber inputs also affect each other.

[Effect of electrical stimulation of second somatosensory cortex on the response of primary somatosensory cortex to C-fiber inputs]

When the projecting point of saphenous nerve in second somatosensory cortex (S II) of cat was stimulated, the evoked potentials elicited by C-fiber inputs of saphenous nerve recorded in the primary somatosensory cortex (C-CEP) might be either inhibited or facilited according to whether the superficial and/or the deeper layer of the cortex was stimulated. The inhibition was expressed as a decrease of amplitude and prolongation of latency of C-CEP; while the facilitation, as an increase of amplitude and duration of C-CEP. When the superfaicial layer of S II was stimulated by weaker current, both inhibitory and facilitatory effects could be observed, but only inhibitory effect was observed, when the deep layer was stimulated. With the same intensity of stimulation, inhibitory effect was more pronounced when the deep layer rather than the superficial layer was stimulated. It is suggested that S II may play a role in the modulation of C-CEP of S I.

[Simple spike response of cerebellar Purkinje cells to stimulation of C-fiber in saphenous nerve]

Simple spike of cerebellar Purkinje cells (PC-SS) was recorded with microelectrode. In the NCCVF (normalized cross-covariance function) histogram, spontaneous PC-SS does not show obvious peak. When the saphenous nerve is stimulated at lower intensities, which elicits the A-fiber input only, the discharge response (A-CED) consists of an early component with a latency of 16.7 +/- 0.9 ms and a late component with a latency of 270.8 +/- 12.8 ms. After A-fibers are blocked selectively by polarizing current, the stimulation at a suprathreshold strength for C-fiber evokes a characteristic response (C-CED) with a latency of 142.4 +/- 4.3 ms. However, the C-CED can not be evoked by the inputs of A- and C-fiber simultaneously. In NPSDF histogram, the spontaneous activities of PC-SS can be divided into two groups, the high and the low peak group. The high peak group (n = 15) has a peak energy value of 15.7 +/- 4.7 x 10(-3) and peak frequency of 4.07 +/- 1.69 Hz. A-fiber input causes an increase of the peak value, while C-fiber input causes a decrease. The low peak group (n = 16) has a peak energy value 8.4 +/- 1.4 x 10(-3) and peak frequency of 3.67 +/- 2.90 Hz. Both A-fiber and C-fiber inputs cause an increase of the peak value, but the effect of A-fiber input was more prominent. The results show that the pure C-fiber input can reach the cerebellar PC and elicit characteristic simple spike response.

Cerebellar evoked potential elicited by stimulation of C-fiber in saphenous nerve of cat

Stimulation of the saphenous nerve above C-fiber threshold strength evoked a field potential which consisted of an early component with latency of 11.8 +/- 3.5 ms and a late component with latency of 312.1 +/- 17.5 ms on the cerebellar cortex. After the A-fibers in saphenous nerve were blocked by the polarizing current selectivity, the stimulation at C-fiber suprathreshold elicited a C-fiber cerebellar evoked potential (C-CEP) with latency of 134.2 +/- 18.4 ms. C-CEP had the maximal amplitude on the vermian lobule VI of the contra- and ipsilateral cerebellar cortex and its phases reversed in the deep layer of this area. It was suggested that the selective C-fiber input could reach the cerebellar cortex and elicit a characteristic evoked potential. However, when A- and C-fiber inputs were elicited simultaneously, C-CEP might be inhibited by the A-fiber input.

[Effect of stimulating midbrain periaqueductal gray on the electrical response of somatosensory cortex to C-fiber input in cats]

The electrical responses of the somatosensory cortex (C-CEP) and spinal cord (C-SSP) to C-fiber inputs could be markedly inhibited by stimulating the periaqueductal gray (PAG), and the inhibition on C-CEP was greater than that on C-SSP. After application of cyproheptadine on the dorsal surface of the spinal cord, PAG stimulation could still inhibit C-CEP, but not C-SSP. It was suggested that PAG might inhibit C-CEP through ascending as well as descending pathways. After blocking the descending inhibitory pathway by cyproheptadine i.v. injection, cyproheptadine and naloxone could antagonize the inhibitory effect of PAG stimulation on C-CEP, indicating that endogenous opiate-like substance and serotonin might play an important role in the transmission of the ascending inhibitory pathways from PAG.

[Influence of stimulation of cerebral anterior lateral association area on cortical potentials evoked by C-fiber inputs in saphenous nerve]

The effect of stimulation of cerebral anterior lateral association area (ALA) on evoked potentials recorded in the primary somatosensory cortex (SI), elicited by C-fiber inputs of saphenous nerve (C-CEP) was investigated in cats anesthetized with chloralose and immobilized by Flaxedil. Following 1 min electric stimulation of ALA (0.1 mA, 100 Hz, duration 0.2 ms), the amplitudes of C-CEP were obviously decreased, indicating that ALA had an inhibitory effect on C-CEP. In order to explore the neural pathway underlying the inhibition of C-CEP by ALA stimulation, a vertical section between ALA and SI was made. It was shown that the inhibition of C-CEP produced by ALA stimulation was reduced considerably and the time course of the inhibition was shortened after the section. Moreover, the ALA stimulation-produced inhibition was also blocked partially 7 min after the intraventricular injection of naloxone (25 micrograms/50 microliters). The results suggest that ALA may exert an inhibitory effect on C-CEP, which is mediated by endogenous opiate like substances and through the nervous connection between ALA and SI. The cerebral association area may play a role in the modulation of C-CEP.

[Electric responses evoked by C-fiber input from saphenous nerve in cat cerebellar cortex]

When the A-fibers of the saphenous nerve were stimulated at a lower intensity which elicited the A-fiber input only, an evoked potential (A-CEP) which consisted of an early component with latency of 11.8 +/- 3.5ms and a late component with latency of 312.1 +/- 17.5ms could be recorded on the surface of the cerebellar cortex in cat. When A- and C-fibers were activated by stimulation at the strength of C-fiber suprathreshold, the latency and configuration of the evoked potential had no significant difference from one of the A-CEP. After A-fibers were blocked by the polarizing current, stimulation at the strength of C-fiber suprathreshold could evoke a characteristic C-CEP with latency of 134.2 +/- 18.4ms. In general, C-CEP whose maximal amplitude was recorded on the vermain lobule VI was a positive-negative potential and its phases were reversed in the deep layer of the cerebellar cortex. C-CEP had a smaller amplitude, a longer latency and a lower following frequency than A-CEP had. In comparison with A-CEP, C-CEP had a high susceptibility to the morphine. The results showed that C-CEP which was evoked by the selective C-fiber input and generated in the cerebellar cortex seemed to be a response to the information of the slow pain input. It was suggested that C-fiber input could reach the cerebellar cortex and elicited an evoked potential. When A- and C-fiber were activated at the same time, C-CEP might be inhibited by the A-fiber input.

Normalized power spectrum density function analysis on spike trains. II. Rhythms of unit activities in the somatosensory cortex of cats

The normalized power spectrum density function (NPSDF) was used to analyse unit activities in the somatosensory cortex of cats. Thirty-four units from 40 cats were recorded and analysed. Rhythmic activities of 2-5 Hz were found in every unit, the strength increasing with mean firing rate and peripheral stimulation while the frequency remained constant. The results suggested: NPSDF is a better method for studying rhythm of unit activities; 2-5 Hz exists in the unit activities of the somatosensory cortex; and peripheral input may have the action of "phase tuning" in addition to the action of time-locked driven firing.

Normalized power spectrum density function analysis on spike trains. I. Mathematical method and its evaluation

The mathematical descriptions of normalized power spectrum density function (NPSDF) for rapidly estimating quantitatively the characteristics of frequency domain of neural spike trains were created and the efficient analytical method was thus established. All the tests and practical applications showed that the method reflects the frequency domain accurately and can satisfy most cases of the analysis in both frequency resolution and calculation speed.

Normalized auto- and cross-covariance functions for neuronal spike train analysis

The normalized auto- and cross-covariance functions of discrete-time stochastic point process, used for quantitatively analyzing neuronal spike trains, were derived from the corresponding functions of general stochastic process using Kronecker delta functions. The auto-correlation and cross-correlation properties can be described as numerical differences on a monotonic scale ranging from -1 -1 to +1. A segmental integration method and a significance test for the normalized cross-covariance function estimate are suggested. Examples from real spike trains are illustrated, and Monte Carlo methods are used for controls and for testing the algorithms and computer programs.