Effects of different antagonists on depolarization of cultured chick myotubes by cobra venom cardiotoxins and Pyrularia thionin from the plant Pyrularia pubera

Cardiotoxins (3.12 and 3.12.1) purified from cobra venom (Naja naja siamensis) are basic single-chain polypeptides of about 60 residues. Although they depolarize nerve and muscle cells and have cytolytic effects, their mechanism of action is still unknown. Pyrularia thionin (P-thionin) isolated from nuts of the parasitic plant Pyrularia pubera is a strongly basic, single-chain polypeptide containing 47 residues. It is known to be haemolytic and cytotoxic, and to depolarize muscle cells, but its mechanism of action is unclear. The present studies explored the possible similarities between P-thionin and cobra venom cardiotoxins by comparing their effects on depolarization of cultured chick skeletal muscle cells in the presence and absence of possible antagonists. Cardiotoxins and P-thionin depolarized cultured chick skeletal muscle cells, but with P-thionin showing a steeper concentration-dependence. Ca2+ was more effective at reducing cardiotoxin action than P-thionin, while the Ca(2+)-channel blockers Ni2+ (100 microM) and verapamil (100 microM) had no blocking effects on the toxins. Ca2+ may block the binding of both toxins. Indomethacin (100 microM, an inhibitor of cyclooxygenase), quinacrine and dexamethasone (100 microM, inhibitors of phospholipase A2) did not block the effects of the toxins, implying that the actions on cultured chick skeletal muscle cells are not due to activation of endogenous phospholipase A2.

Reusability of Bond Elut Certify columns for the extraction of drugs from plasma

The reusability of Bond Elut Certify columns for the extraction of toxicologically relevant drugs from plasma has been evaluated. Pentobarbital, hexobarbital, mepivacaine, trimipramine and clonazepam were selected as test drugs to represent various classes of drugs. The columns were regenerated immediately after an extraction by washing with methanol, hydrochloric acid (1%), water and methanol, sequentially. These regenerated columns were found to be reusable for plasma. More than 85% of the test drugs were recovered when the columns were used three times. However, the extraction power of the regenerated columns decreased slightly with the number of reuses, so that a column should not be used more than two or three times.

Study of lot-to-lot reproducibilities of Bond Elut Certify and Clean Screen DAU mixed-mode solid-phase extraction columns in the extraction of drugs from whole blood

The lot-to-lot reproducibilities of Bond Elut Certify and Clean Screen DAU columns are described. The recoveries of five test drugs obtained from twelve lots of Bond Elut Certify columns ranged from 84 to 104% with standard deviations of less than 9%. The recoveries of five test drugs obtained from six lots of Clean Screen DAU columns ranged from 81 to 103% with standard deviations of less than 7%. The 95% confidence intervals of the means as obtained by ANOVA demonstrate that there are no significant differences between the tested lots of Bond Elut Certify and Clean Screen DAU columns. Comparison of the two brands shows that both Bond Elut Certify and Clean Screen DAU columns are well acceptable for routine drug screening in systematic toxicological analysis, with a slightly higher overall recovery for the former.

Solid phase extraction of morphine from whole blood by means of Bond Elut Certify columns

The use of Bond Elut Certify columns for the isolation of morphine from whole blood was evaluated. In order to monitor possible losses and the elution profile of morphine, a small amount of the tritiated analogue was added to the samples. Four sample pretreatment methods, three protein precipitation methods and one sonication/dilution method, were tested. The latter one gave the best results. The blood sample was applied onto the column at pH 3.3 after sonication and dilution with 0.1 M phosphate buffer (pH 3.3). The retention of morphine was affected by the pH of the samples, and the loss of morphine during sample application was minimized at low pH (3.3). The interferences were removed by washing the column with the phosphate buffer, 0.01 M acetic acid (pH 3.3), and methanol, sequentially. Ammoniated methanol, 2 mL at 2%, was selected to elute morphine. As a result, more than 80% of 3H-morphine was recovered for concentrations of morphine ranging from 5 to 4000 ng/mL.

Semi-automated solid-phase extraction procedure for drug screening in biological fluids using the ASPEC system in combination with Clean Screen DAU columns

The use of a semi-automated solid-phase extraction system (ASPEC) for the screening of drugs in plasma and urine on a single mixed-mode column (Clean Screen DAU) is described. The processes of column preconditioning, sample application, column wash, pH adjustment and elution of the drugs were accomplished by the ASPEC. After off-line evaporation, the residues were injected into a wide-bore capillary gas chromatograph. The recoveries of the tested drugs were in the range of 73-96%, with relative standard deviations less than 5% at a concentration level of 2 micrograms/ml.

[Synthesis and antitumor activity of 4-(2-amido-2-ethoxycarbonyl) ethylsulfenyl-4-deoxy-4'-demethylepipodophyllotoxin analogues]

Twenty three 4-(2-amido-2-ethoxycarbonyl) ethylsulfenyl-4-deoxy-4'-demethylepipodophyllotoxin analogues were synthesized by three steps, in which trifluoroacetic acid was used as a condensation agent of 4'-demethylepipodophyllotoxin with L-cysteine ethyl ester hydrochloride without any protection of phenolic hydroxy and amino groups. All compounds were screened in vitro against L1210 leukemia and KB cells, in which, compounds 11, 16 and 18 exhibited more potent antitumor activity than etoposide.

Superior cervical ganglionic origin of sympathetic fibers in the facial nerve, and their preganglionic spinal inputs: a WGA-HRP study in Macaca fuscata

The origin of sympathetic fibers in the facial nerve of Macaca fuscata was demonstrated using the HRP method. WGA-HRP injection into the facial nerve resulted in heavy labeling in the ipsilateral superior cervical ganglion. The majority of labeled neurons in the superior cervical ganglion had sizes ranging from 20 to 35 microns. In the present study it was of particular interest that labeled neurons are also found in the intermediolateral nucleus and lateral funiculus ipsilaterally at the level from the C8 to T4 spinal cord segments. Many labeled neurons in the lateral funiculus were located in close vicinity to the intermediolateral nucleus, and, characteristically, a few of these had a long dendrite extending to the lateral surface of the spinal cord. The labeling in the spinal cord appears to be caused by transneuronal transport of WGA-HRP.

Midbrain tegmentum as an intermediate relay station of the periaqueductal-facial pathway in the cat

Iontophoretic injection of horseradish peroxidase (HRP) into the medial part of the facial nucleus resulted in retrograde labeling in the lateral midbrain tegmentum contralaterally which corresponded to the paralemniscal zone (PL). Further experiments in which HRP was injected iontophoretically into the PL revealed heavy retrograde labeling in the lateral portion of the ipsilateral periaqueductal gray (PAG). These light microscopic studies indicated the possibility of the pathway from the PAG to the facial nucleus via the midbrain PL. The electron microscopic observations were carried out on the lateral midbrain tegmentum containing the PL after kainic acid, and wheat germ agglutinin conjugated HRP injections were made into the PAG and the contralateral facial nucleus in the same animal, respectively. Although in the neuropil many degenerating PAG fibers and retrogradely labeled neurons were observed, it was of particular interest that the degenerating fibers made synaptic contacts with HRP-labeled somata and dendrites.

Isolation of acidic, neutral, and basic drugs from whole blood using a single mixed-mode solid-phase extraction column

A solid-phase extraction procedure was developed for the isolation of acidic, neutral, and basic drugs from whole blood. A blood sample was sonicated, diluted with phosphate buffer, and the drugs were extracted on a mixed-mode bonded-phase silica column at pH 6.0. The extraction system was adjusted to pH 3.3 with acetic acid. After column drying, the drugs were selectively eluted from the column by two different eluates, which were collected separately. Acidic, neutral, and weakly basic drugs with lower pKa values (e.g., benzodiazepines) were present in the first acetone-chloroform (1:1) fraction. The other basic drugs were present in the second fraction (basic ethyl acetate). The drugs with pKa's close to the pH of the extraction system (pH 3.3) appeared in both fractions. The two fractions were evaporated until approximately 100 microL of solvent remained in the tube and were then analyzed on a gas chromatograph equipped with a wide-bore capillary column and flame ionization detector. The absolute recoveries of all tested drugs exceeded 81% at a concentration of 2 micrograms/mL.

Antinociception produced by 2 and 5 KHz peripheral stimulation in the rat

Recently a "medium frequency" electric stimulator (LIKON) was marketed, which delivers 2000-5000 Hz square waves and was claimed to induce a strong clinical analgesic effect. The aim of this study was to clarify whether electric stimulation over 1000 Hz would induce any antinociceptive effect in the rat. Tail flick latency (TFL) was taken as the nociceptive index. Electrical stimulation was applied via stainless steel pins inserted into the acupoint ST 36 located near the knee joint and SP 6 located near ankle joint on both hind legs. Significant increase of TFL (ANOVA, p < .01) was obtained after 2 or 5 kHz stimulation for 10 min, and lasted for the whole stimulation period of 30 min. No significant difference was observed whether the amplitude remained constant (5 V) or was modulated at 5 or 100 cycles/s. Opioid antagonist naloxone (20 but not 10 mg/kg, sc) produced a 50% blockade of the antinociception induced by 2 kHz, but not 5 kHz stimulation. The results suggest that 2 kHz peripheral stimulation was capable of inducing an opioid mediated antinociception in the rat, whereas a less marked antinociception induced by 5 kHz stimulation was nonopioid in nature.

Analgesia induced by electroacupuncture of different frequencies is mediated by different types of opioid receptors: another cross-tolerance study

The cross-tolerance technique was used to analyze the receptor mechanisms of analgesia induced by electroacupuncture (EA) of 2 Hz, 100 Hz, or 2-15 Hz. (1) Rats were given EA stimulation of 2 Hz, 100 Hz and 2-15 Hz for 30 min with 30 min intervals successively. The percentage increase in tail-flick latency (TFL) was taken to indicate the intensity of EA analgesia. Rats made tolerant to repeated intrathecal injection of the mu-opioid agonist ohmefentanyl (OMF, 15 pmol, Q2h x 5) or the delta-opioid agonist DPDPE (10 nmol, Q2h x 5) showed a cross tolerance to both 2 Hz- and 2-15 Hz-, but not to 100 Hz-EA analgesia; and rats made tolerant to kappa-opioid agonist dynorphin-(1-13) (5 nmol, Q2h x 5) showed a cross-tolerance to 100 Hz- and 2-15 Hz-, but not to 2 Hz-EA analgesia; (2) Rats made tolerant to 2-15 Hz EA showed cross-tolerance to either 2 Hz- or 100 Hz-EA analgesia; (3) Rats made tolerant to either 2 Hz- or 100 Hz-EA were still reactive to 2-15 Hz-EA. The results indicate that 2 Hz-EA analgesia is mediated by mu- and delta-receptors, 100 Hz-EA analgesia by kappa-receptor, and 2-15 Hz-EA analgesia by combined action of mu-, delta- and kappa-receptors in the spinal cord of the rats.

The microvasculature of human oral mucosa using vascular corrosion casts and India ink injection. I. Tongue papillae

The microvasculature of human tongue papillae originating from 9 males and 6 females, aged 0.5 to 2 years was studied by scanning electron microscopy (SEM) of vascular corrosion casts and by light microscopy (LM) of India ink injected specimens. All papillae showed a microvasculature characterized by primary, secondary and tertiary capillary loops. In the filiform papillae the loops were generally arranged in a corolla-like pattern with the tertiary loops demonstrating a hair-pin shape. The fungiform papillae showed basically a similar architectural pattern although the loops were somewhat more compact and complex in structure. A small, shallow depression of the tertiary loops at the top of these papillae was found to be occupied by a prominent rete ridge of the surface epithelium. There was a gradual transition from filiform to foliate papillae, the latter appearing as rows of coalesced filiform papillae. The circumvallate papillae easily identified by the surrounding furrow showed a rather complex and compact pattern of capillary loops of which typical hair-pin shaped tertiary loops dominated the periphery of the papilla. Small grooves or depressions in the vascular network were found to be occupied by rete ridges of the overlying mucosal epithelium.

Application of Empore C-8 extraction disks for screening urine in systematic toxicological analysis

Solid-phase extraction (SPE) by means of disposable columns has become a widely accepted technique for sample pretreatment in toxicology, both for directed analyses and for screening analyses. However, the sample capacity in SPE is usually limited to a few millilitres. Therefore, we have investigated to what extent these problems can be overcome by using Empore extraction disks, consisting of chemically modified C-8 reversed-phase silica, embedded in an inert polytetrafluoroethylene (PTFE) matrix. Human urine was selected as the matrix and dexetimide and mepyramine were initially used as test drugs because these drugs were available in tritiated form. Additional drugs investigated included codeine, hexobarbital, imipramine, methamphetamine, and nitrazepam. In these investigations, the sample capacity for untreated urine was at least 25 mL, and analyte quantities up to 250 micrograms could be retained by these filters. Washing with water/methanol mixtures was successful in removing substantial amounts of endogenous interferences, and methanol proved to be an acceptable eluent. Thus, these disks seem to have interesting potential for toxicological analysis in that sample concentration and cleanup can be achieved at the same time.

All three types of opioid receptors in the spinal cord are important for 2/15 Hz electroacupuncture analgesia

The analgesic effect induced by 2/15 Hz electroacupuncture as shown by the increase in tail flick latency decreased steadily as electroacupuncture stimulation was given continuously for 6 h, showing the development of tolerance to electroacupuncture analgesia. These rats were then given an intrathecal (i.t.) injection of one of the following opioid agonists: the mu agonist, ohmefentanyl 7.5, 15 and 30 pmol, 10 min apart; the delta agonist, [D-Pen2,D-Pen5]enkephalin (DPDPE) 5, 10 and 20 nmol, 10 min apart and the kappa agonist, dynorphin-(1-13) 2.5, 5 and 10 nmol, 10 min apart, respectively. The analgesic effect induced by ohmefentanyl, DPDPE or dynorphin was dramatically reduced in rats rendered tolerant to 2/15 Hz electroacupuncture analgesia. Rats were injected i.t. with one of the three specific opioid antagonists: the mu antagonist, beta-funaltrexamine (beta-FNA) (5, 10 and 20 nmol), the delta antagonist, ICI174,864 (1, 2 and 4 nmol) and the kappa antagonist, nor-binaltorphimine (nor-BNI) (3.125, 6.25 and 12.5 nmol). It was found that analgesia induced by 2/15 Hz electroacupuncture stimulation was significantly and almost totally blocked by any one of the three opioid antagonists. These results suggest that all three types of opioid receptors, the mu, delta and kappa receptors in the spinal cord of the rat play important roles in mediating analgesia induced by electroacupuncture of 2/15 Hz.

CT-guided stereotactic injection of radionuclide for treatment of brain tumors

The authors report on 40 brain tumor patients treated with CT-guided stereotactic injection of 198Au and 32P. Among the 40 cases were astrocytoma in 23 cases, craniopharyngioma in 9, meningioma in 4, pituitary adenoma in 2, and pinealoma and metastatic carcinoma each in 1 case. The tumors were all located in deep or important areas of the brain which were difficult to deal with by conventional operation. 62 injections of colloidal isotopes were performed, and all were successful. No major adverse effects or complications occurred on follow-up of 6-12 months, 28 patients were improved in their clinical symptoms, and CT scanning showed that the tumor sizes were diminished. The effective rate is 70%.

A single-column procedure on Bond Elut Certify for systematic toxicological analysis of drugs in plasma and urine

A single-column solid-phase extraction procedure was developed for the screening of acidic, neutral, and basic drugs from plasma. The recoveries of all 25 tested drugs exceeded 82%. After the plasma had been diluted with phosphate buffer (pH 6.0), the drugs were extracted using a single Bond Elut Certify column. The acidic and most of the neutral drugs were eluted by acetone/chloroform (1:1) and the basic drugs were eluted by 2% ammoniated ethyl acetate. Some neutral drugs appeared in both fractions. The two fractions were collected separately and evaporated until approximately 100 microL of solvent remained in the tube. Both fractions were analyzed separately on a gas chromatograph equipped with a wide-bore capillary column and a flame ionization detector. The procedure could also be used for urine samples.

Effect of low- and high-frequency TENS on Met-enkephalin-Arg-Phe and dynorphin A immunoreactivity in human lumbar CSF

Transcutaneous nerve stimulation (TENS) treatment was given for 30 min to 37 patients divided into 3 groups of 10 patients and 1 group of 7 patients. Two groups received low-frequency (2 Hz) and the other 2 groups high-frequency (100 Hz) stimulation. A diagnostic lumbar cerebrospinal fluid (CSF) sample was obtained immediately before and after stimulation. The CSF samples were subjected to analysis of immunoreactive (ir) opioid peptides, Met-enkephalin-Arg-Phe (MEAP) from preproenkephalin and dynorphin A (Dyn A) from preprodynorphin, respectively. Low frequency TENS applied on the hand and the leg resulted in a marked increase (367%, P less than 0.05) of ir-MEAP but not ir-Dyn A, whereas high-frequency (100 Hz) TENS produced a 49% increase in ir-Dyn A (P less than 0.01) but not ir-MEAP. This is the first report in humans that 2 Hz and 100 Hz peripheral stimulation induces differential release of peptides from preproenkephalin and preprodynorphin, respectively.

Characterization and localization of two ion-binding sites within the pore of cardiac L-type calcium channels

L-type Ca channels from porcine cardiac sarcolemma were incorporated into planar lipid bilayers. We characterized interactions of permeant and blocking ions with the channel's pore by (a) studying the current-voltage relationships for Ca2+ and Na+ when equal concentrations of the ions were present in both internal and external solutions, (b) testing the dose-dependent block of Ba2+ currents through the channels by internally applied cadmium, and (c) examining the dose and voltage dependence of the block of Na+ currents through the channels by internally and externally applied Ca2+. We found that the I-V relationship for Na+ appears symmetrical through the origin when equal concentrations of Na+ are present on both sides of the channel (gamma = 90 pS in 200 mM NaCl). The conductance for outward Ca2+ currents with 100 mM Ca2+ on both sides of the channel is approximately 8 pS, a value identical to that observed for inward currents when 100 mM Ca2+ was present outside only. This provides evidence that ions pass through the channel equally well regardless of the direction of net flux. In addition, we find that internal Cd2+ is as effective as external Cd2+ in blocking Ba2+ currents through the channels, again suggesting identical interactions of ions with each end of the pore. Finally, we find that micromolar Ca2+, either in the internal or in the external solution, blocks Na+ currents through the channels. The affinity for internally applied Ca2+ appears the same as that for externally applied Ca2+. The voltage dependence of the Ca(2+)-block suggests that the sites to which Ca2+ binds are located approximately 15% and approximately 85% of the electric field into the pore. Taken together, these data provide direct experimental evidence for the existence of at least two ion binding sites with high affinity for Ca2+, and support the idea that the sites are symmetrically located within the electric field across L-type Ca channels.

CT-guided stereotactic evacuation of hypertensive intracerebral hematoma

From January 1986 to June 1989, the CT-guided stereotactic evacuation was performed in 38 cases of hypertensive intracerebral hematoma with satisfactory result. 24 patients were male and 14 female. The age ranged from 37 to 78 years, with an average of 55. 24 cases had their hematoma in internal capsule, 7 in cerebellum, 5 in subcortex, and 2 in brain stem. The interval between the occurrence of hemorrhage and evacuation of hematoma was 24 hours or less in 18 cases, 2-3 days in 14 and 4-7 days in 6. The volume of hematoma was estimated by CT scanning being more than 100 ml in 6 cases whereas much less in 2 cases of the brain stem.

[Detection of C-reactive protein in patients with epidemic cerebrospinal meningitis by solid phase radioimmunoassay]

A modified solid phase RIA was developed for the quantification of C-reactive protein in human serum and CSF. The lowest measurable amount detected by this method was 5 ng/ml (0.25 ng/well). The serum levels in 68 healthy blood donors were with in the range from 0.028-3.4 micrograms/ml, with a median value of 0.166 micrograms/ml (mean = 1.57 micrograms/ml); whilst those in 63 patients with epidemic cerebrospinal meningitis were up to 520 micrograms/ml with a median value of 77.5 micrograms/ml (mean = 88.46 micrograms/ml). This is 400-500-fold higher than that of the normal. The levels of CRP in the sera collected during acute stage of the infection (ranged from 28.5-540 micrograms/ml, with a median value of 200 micrograms/ml, mean = 200.6 micrograms/ml) were 400-fold higher than that after recovery (ranged from 0.1-54 micrograms/ml, with a median value of 0.53 micrograms/ml). In addition, lower levels (0.07-150 micrograms/ml, median = 2.07 micrograms/ml) of CRP were detected in CSF. These results markedly revealed that the CRP reflected the characteristics of an acute phase protein in the infection, and would be usefull for the differential diagnosis of bacterial and nonbacterial meningitis, and in monitoring the clinical course of the illness.

Evacuation of hypertensive intracerebral hematoma by a stereotactic technique

30 patients with a hypertensive intracerebral hematoma were treated by stereotactic evacuation between 1986 and 1988. There were 20 males and 10 females; their ages ranged from 37 to 78 years. The time interval from onset to operation was in 16 patients 24 days and in 14 patients 2-7 days. In 19 patients the hematoma was found in the internal capsule, in 5 in the cerebellum, in 4 in the subcortex, and in 2 in the brain stem. The operation was performed with a Leksell computed tomography guided stereotactic apparatus and a Backlund hematoma evacuator. More than 80% of the hematoma could be aspirated in 20 patients and 60-80% in 10. 29 patients are alive, and 1 patient died.

[Studies on oncogene and its products of human nasopharyngeal carcinoma]

Oncogene of nasopharyngeal carcinoma (NPC) by means of external origin DNA transfection experiment and its gene products by immunohistochemical method have been studied. These DNAs were isolated from human primary poorly differentiated NPC tissues and were transfected into NIH/3T3 mouse fibroblasts to induce the foci of the morphologically transformed cells in the culture, while DNAs of normal placenta tissues failed to do so. The DNAs were extracted from the primary and secondary transformed cells to analyse human sequence with human Alu sequence probe. The human sequence has been detected in the DNAs of the primary and secondary transformed foci cells, while none of the human sequence was detected in the DNAs of the control. The results indicated that human transforming sequences had been integrated into transformed cells. The malignant properties of the transformed foci cells were evidenced by tumorigenic experiment of nude mice. The transformed foci cells were inoculated subcutaneously in the nude mice and induced fibrosarcoma in vivo. The tumorigenic rate was 87.5%. It was further demonstrated that DNAs from human NPC possessed carcinogenicity and induced malignant transformation. The primary result revealed that the transforming gene of NPC may be homologue to Ha-ras oncogene. The expression of Ha-ras gene products-p21 has been studied in human NPC tissues. The primary results showed a positive expression of p21 in human NPC tissues by immunohistochemical method. The positive rate was 90.4%.

[Effects of aliphatic alcohols on slow action potential of guinea-pig papillary muscle]

Effects of ethanol, butanol, hexanol and octanol on slow action potential (APA, APD50, Vmax, and V'max) and its correspondent ICa (Imax) and Ik (I'max) of guinea-pig papillary muscle were measured and analysed by using phase-plane method. The results showed that all of four alcohols inhibited calcium current of cardiac membranes, but the action on potassium current changed from enhancement (ethanol) to impairment (hexanol and octanol) with the increase in carbon number of alcohols. Furthermore, the longer the chains of alcohols, the less the concentration needed to produce these effects. This phenomenon suggests a possible correlation between the actions of aliphatic alcohols and their hydrophobic properties.

Pathology of eosinophilic fasciitis and its relation to polymyositis

The anatomical substrate of eosinophilic fasciitis (EF) was studied in 15 muscle biopsy specimens of this disease, six of which included the dermis and subcutaneous tissue. As controls, 94 postmortem muscle specimens from patients dying of non-muscular diseases were used. Of these 94 specimens, 22 (23.4%) showed practically no deep fascia and 72 specimens showed a single dense bundle of collagen with no distinction between deep fascia and epimysium. The 15 specimens of EF showed thickening and inflammatory infiltration of varying degrees in the deep fascia, epimysium, perimysium, endomysium and also in muscle. We conclude that the anatomical substrate of EF is not confined to the deep fascia, but involves other structures including mysia and muscle itself. Most reported cases of EF in the literature do not even describe muscle. A comparative study of 15 biopsy specimens of polymyositis and dermatomyositis with those of EF revealed only quantitative differences in the histopathological changes of muscle and mysia, inflammatory infiltrate and eosinophilia. We suggest that the diseases are more closely related than previously recognized.

Neurophysiology of limbic system pathways in the rat: projections from the amygdala to the entorhinal cortex

We studied the responses of rat entorhinal neurons to electrical stimulation of the amygdala. Four main results were obtained: (1) excitatory postsynaptic potentials were recorded in entorhinal neurons in response to electrical stimulation of the amygdala. Cells in layers II, III and V of the entorhinal cortex were responsive. (2) Excitatory responses were followed by inhibitory postsynaptic potentials. (3) Frequency potentiation of both excitatory and inhibitory responses was observed when 10/s stimulation was used. (4) Three amygdala neurons were antidromically activated by entorhinal stimulation; and two layer II entorhinal cells that were excited by amygdala stimulation were also antidromically activated by dentate gyrus stimulation. These results provide evidence for a monosynaptic, excitatory projection from the amygdala to the entorhinal cortex. In addition, the data indicate that amygdala neurons are only one synapse removed from the excitation of dentate gyrus granule cells.

Effect of chronic irradiation of 60Co-gamma-ray at low dose rate on rhesus monkey - effect on peripheral blood and testis

The authors have demonstrated that after a long-term chronic irradiation of 2.17 rad/day for 2 months, the testis of the experimental monkey (Macaca mulatta) is extremely atrophied with a loss of reproductive ability. But the effect on peripheral blood is not apparent even after irradiation for 57 months. It should be noted that rhesus monkeys, being as sensitive to irradiation and similar in evolutionary steps as human beings, could be used as experimental animals to further study the dose rate for aspermatogenesis, the morphological injuring effect on the reproductive system and the cytogenetic effect of irradiation, and this is highly important to working out a standard of promised dose of irradiation for X-ray workers and an index or radiation protection monitoring.