Naloxone-sensitive inhibition of nicotinic transmission in the superior cervical ganglion of the cat

In anesthetized, artificially ventilated cats, pretreated with the muscarinic antagonist scopolamine, the effect of naloxone on the efficacy of nicotinic transmission in the superior cervical ganglion was used as a test of endogenous opioid release by the preganglionic axons. The cervical sympathetic trunk (CST) was split into two bundles. The compound action potential (CAP), evoked by supramaximal low-frequency stimulation (0.25 Hz) of one CST bundle, was recorded from a postganglionic nerve of the superior cervical ganglion. Partial block with hexamethonium was used to reduce the 'safety factor' of nicotinic transmission. A conditioning train (5 Hz, 40 s, supramaximal) to the other CST bundle (heterosynaptic conditioning) inhibited the CAP. At the peak of the inhibition the CAP was attenuated by 51 +/- 4%. Recovery was 90% complete in 201 +/- 28 s. The inhibition was antagonized in a dose-dependent manner by i.v. naloxone with an apparent IC50 of 60 +/- 12 micrograms/kg. The maximum effect obtained with naloxone was an 80% decrease in the magnitude of the inhibition. Magnitude and duration of the heterosynaptic inhibition were related to frequency, duration and intensity of the conditioning train. Naloxone-sensitive inhibition was observed with frequencies of the conditioning train as low as 0.5 Hz. A train (5 Hz, 40 s) to the postganglionic nerves produced a naloxone-insensitive depression of the orthodromic test CAP which was of smaller amplitude and duration than when the conditioning train was applied to the preganglionic axons.(ABSTRACT TRUNCATED AT 250 WORDS)

PAF-induced bowel necrosis. Effects of vasodilators

Ischemic bowel necrosis in the rat is produced by injecting platelet-activating factor (PAF) intravenously. Since intestinal hypoperfusion is observed after PAF injection, we hypothesize that mesenteric vasoconstriction is the mechanism of bowel injury. We thus studied the effects of vasodilators in this model. We found that: (1) Phenoxybenzamine, prazosin, ICI 198615 (leukotriene antagonist) and PGE1 counteracted the PAF-induced mesenteric flow reduction and ameliorated the bowel injury. However, phenoxybenzamine and prazosin were relatively ineffective in correcting PAF-induced hypotension, showing that bowel injury can be prevented independently of the hypotensive state. (2) Nitroglycerin failed to prevent bowel injury, although it improved the mesenteric blood flow. Thus, in opposition to our initial hypothesis, correction of the mesenteric flow reduction induced by PAF does not always prevent intestineal necrosis. (3) Only phenoxybenzamine, prazosin, ICI 198615, and PGE1 ameliorated PAF-induced hemoconcentration and bowel injury. This suggests a correlation between vascular injury (expressed by "leaky" vessels and the consequent hemoconcentration) and bowel necrosis. (4) Although both nitroglycerin and hydralazine relax smooth muscle, hydralazine seemed to aggravate bowel necrosis. The mechanism remains unclear.

Fetal tissue grafts for cerebellar atrophy

It has been shown in a rat model that surgical injury to the right cerebellum with resultant ataxia can be corrected by implantation of embryonic cerebellar tissue into the injured cerebellum. Histological examinations of the cerebellar tissue revealed that mitoses of Purkinje cells of the implanted group were increased substantially over the control group's. The surgically induced ataxia resolved more rapidly in the cerebellar implant group than the control group. Based on this experimental data, a similar technique was applied in 6 patients with severe hereditary cerebellar degenerative ataxia. The preliminary results in these 6 surgically implanted patients with heredity degenerative cerebellar disease show 2 with marked improvement, 3 with moderate improvement and 1 with improvement for 2 months followed by mild deterioration but still better than presurgery. We also studied immunological markers in the blood and CSF in an attempt to determine whether rejection of implanted tissue occurs.

Impaired secretion of growth hormone-releasing hormone, growth hormone and IGF-I in elderly men

The GHRH test and L-dopa test were performed in 12 normal young men (24.1 +/- 1.1 years) and 12 normal elderly men (77.8 +/- 1.4 years) to investigate age-related changes in secretion of GHRH, GH and IGF-I. The basal plasma levels of GHRH and GH were not significantly different in young and elderly men, but the basal plasma level of IGF-I was higher in the young men (159.0 +/- 11.7 vs 86.7 +/- 11.6 micrograms/l). The area under the curve for plasma GH in the GHRH test was less in the elderly group (35.1 +/- 5.9 vs 11.2 +/- 2.1 micrograms.h-1.l-1, p less than 0.001). The AUCs for the plasma GHRH and GH responses in the L-dopa test in young and elderly men were 32.0 +/- 2.7 vs 20.3 +/- 1.8 ng.h-1.l-1 (p less than 0.001), and 21.8 +/- 4.6 vs 5.4 +/- 1.1 micrograms.h-1.l-1 (p less than 0.01), respectively, indicating decreased releases of GHRH and GH in the elderly. Correlations between the AUCs for plasma GHRH and GH responses in L-dopa were found in both groups, but the ratio of the AUCs for GH/GHRH was lower in the elderly group. The elderly group showed a significant correlation between the basal plasma IGF-I level and the AUCs for plasma GH in the GHRH and L-dopa tests. These results suggest that elderly men have a decreased reserve of hypothalamic GHRH, resulting in secondarily impaired GH release, which may lead to a lower level of IGF-I than in young men.

[Electroretinogram of normal rabbits (experimental research)]

Electroretinograms of 44 eyes (22 normal rabbits) were studied. Of them, 11 were albinotic and 11 colored. The highest amplitude of the a-wave was 87.90 +/- 22.70 microV. No statistically significant difference was found between the two groups. The highest amplitude of the b-wave was 241.4 +/- 43 microV in the albinotic and 220.06 +/- 26.9 microV in the colored rabbits (P less than 0.01). In each group of the rabbits, the b-wave amplitude increased when the flash intensity increased both in dark-adapted ERG and in light-adapted ERG.

Effect of precursors on the synthesis of catecholamines and on neurotransmission in the superior cervical ganglion of the rat

Male Sprague-Dawley rats (325-350 g) were anesthetized with urethane (1.5 g/kg i.p.) and treated with physiological saline, Aspartame (APM; 552 mumols/kg), or tyrosine (Tyr; 552 mumols/kg). Ganglionic transmission and the synthesis of dopamine (DA) and norepinephrine (NE) were measured in the superior cervical ganglion (SCG) following electrical stimulation of the cervical sympathetic trunk (CST). When the CST was stimulated with single pulses, neither APM nor Tyr affected the synthesis of NE or DA. However, in response to low- (5 Hz, 20 s) and high- (20 Hz, 20 s) frequency pulses, the metabolism of DA was increased (p less than 0.05), but to the same extent after saline, APM, or Tyr. In rats stimulated with similar low- and high-frequency pulses, the synthesis of NE was increased significantly (p less than 0.05) after Tyr, but not after APM or saline. In saline-treated controls, ganglionic transmission was not changed in response to single pulses, or low- or high-frequency stimulation. However, after treatment with APM, ganglionic transmission was depressed significantly (p less than 0.01) in response to high-frequency stimulation (single: 0.46 +/- 0.09 mV; low: 0.39 +/- 0.07 mV; high: 0.27 +/- 0.07 mV). After treatment with Tyr, ganglionic transmission was depressed significantly (p less than 0.05) in response to both low- and high-frequency stimulation (single: 0.44 +/- 0.04 mV; low: 0.22 +/- 0.12 mV; high: 0.26 +/- 0.07 mV). In the nonstimulated SCG, L-3,4-dihydroxy-phenylalanine (25 mg/kg) caused a rapid, significant (p less than 0.01) increase in the synthesis and metabolism of DA, but not of NE.(ABSTRACT TRUNCATED AT 250 WORDS)

[Dissolvable supporting in small artery anastomosis: an experimental study]

Intra-lumen supporting, made of biomaterial, non-toxic, tissue-compatible, and dissolvable, was used in anastomosing femoral artery on one side of 51 rabbits, while that on other side was anastomosed by conventional procedure for comparison. Results showed that suturing on the experiment group could be accomplished with better accuracy, less trauma and avoidance of puncturing the opposite wall, and with higher speed, shorter operation time than the contra. Better still, the intra-lumen supporting stabilized the vessel stumps and dilated the segments being handling, so that torsion and spasm were prevented. The intra-lumen supporting was then dissolved and no thrombosis developed in any of the experiment ones but some of the contra. Histological observation revealed that repair of tissue in each layer of the artery wall at the anastomosis site proceeded much quicker in the experiment ones than in the contra. We are impressed, through this survey, that the newly formed endothelial cells cover in the juncture area may arise from the uninjured endothelium nearby, and may also come from monocytes in the circulation.

[Immunomodulatory action of the total saponin of Gynostemma pentaphylla]

The specimen of the total saponin for this experimental study was extracted from Gynostemma pentaphylla growing in Suining county in Hunan province. Weight of immune organs, content of anti-SRBC hemolysin, rate of special Ea-RFC formation and percentage of NK cell activity had been employed for the study as experimental indices, both the normal healthy mice and the mice with immunity impairment due to Cyclophosphamide (Cy) management as experimental models. The results of the study exhibited: (1) The total saponin of Gynostemma pentaphylla could markedly act against the immunity inhibition due to Cy management in the experimental animals, showing a variant recovery in mice treated by Cy in weight of the immune organs, content of hemolysin, forming rate of Ea-RFC and unequivocally elevating NK cell activity, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (2) The total saponin showed a definite of bidirective immunomodulatory action in normal healthy mice, recovering the immune indices to normal value from either originally lower or higher than the medium figure, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (3) The total saponin had actions to prevent from fatigue and to tolerate hypoxia under usual atmospheric pressure. The above description indicates that the total saponin of Gynostemma pentaphylla is a better immunomodulator, seems to be like the actions of some Chinese drugs, for example, Panax ginseng, Astragalus membranaceus etc.

Thermal denaturation of the Ca2(+)-ATPase of sarcoplasmic reticulum reveals two thermodynamically independent domains

Inactivation of Ca2+ uptake and ATPase activity of the Ca2(+)-ATPase of rabbit sarcoplasmic reticulum was measured and compared to the thermal denaturation of the enzyme as measured by differential scanning calorimetry (DSC) and fluorescence spectroscopy. Two fluorophores were monitored: intrinsic tryptophan (localized in the transmembrane region) and fluorescein isothiocyanate (FITC)-labeled Lys-515 (located in the nucleotide binding domain). Inactivation, defined as loss of activity, and denaturation, defined as conformational unfolding, were irreversible under the conditions used. Activation energies (EA) and frequency factors (A) for inactivation were obtained for the enzyme in 1 mM EGTA and 1 mM Ca2+. These were transformed to a transition temperature for inactivation, Tm (defined as the temperature of half-inactivation when temperature is scanned upward at 1 degree C/min). All denaturation profiles were fit with an irreversible model to obtain EA and Tm for each transition, and the values of these parameters for denaturation were compared to the values for inactivation. In EGTA, denaturation obeys a single-step model (Tm = 49 degrees C), but a two-step model is required to fit the DSC provile of the enzyme in 1 mM Ca2+. The specific locations of tryptophan and the fluorescein label were used to demonstrate that denaturation in Ca2+ occurs through two distinct thermodynamic domains. Domain I (Tm = 50 degrees C) consists of the nucleotide binding region and most likely the phosphorylation and transduction regions [MacLennan, D. H., Brandl, C. J., Korczak, B., & Green, N. M. (1985) Nature 316, 696-700].(ABSTRACT TRUNCATED AT 250 WORDS)

[Influence of subtotal gastrectomy on bile acid concentration, total bacterial counts in the gastric juice, and histologic changes in the gastric mucosa]

The concentrations of bile acids, PH and total bacterial counts in the gastric juice were measured among 44 patients with peptic ulcer before and after subtotal gastrectomy (Billroth II in 14 cases, Billroth I in 10 cases, and PAFPG in 20 cases). Thirty three patients were studied by endoscopy and gastric mucosa biopsy one year after the surgery. The results showed that the fasting gastric bile acids concentrations in both B-II and B-I groups were significantly higher than in PAFPG group, when examined 3 weeks and 1 year postoperatively. The PH and total bacterial counts in gastric juice were increased significantly after B-II and B-I reconstruction compared with PAFPG. The abnormal histology of gastric remnant mucosa was more common in B-II or B-I groups than in PAFPG (P less than 0.05). Our data demonstrated that B-II and B-I gastrectomy caused considerably enterogastric reflux, while PAFPG prevented it effectively by keeping the gastric physiology in a relatively stable status. It is the authors' belief that the results provide objective basis for selecting surgical procedure and evaluating operative effects.

[Preventive effects of fortified pollen on diphenylhydantoin teratogenesis]

This paper reports the preventive effects of fortified pollen and folic acid on diphenylhydantoin (DPH) teratogenesis in pregnant SD rats. The experiment showed that i.p. injection of DPH 75mg/kg per day to pregnant rats on gestational days 7 through 11, and feeding of fortified pollen (pollen 10g/kg per day plus folic acid 20mg/kg per day) or folic acid (20mg/kg per day) on gestational days 0 through 20 may partly prevent the embryotoxicity and fetal toxicity produced by DPH. However, the preventive effects of fortified pollen is better than those of folic acid on the following: decrease of fetal body weight; retarded ossification of metacarpus, proximal phalanx, metatarsus, and supraoccipital bone; sternebrae ossification agenesis; subcutaneous hemorrhage; single eye defect; hydronephrosis and the widening of subarachnoid space. This paper also discusses the possible mechanism of prevention of fortified pollen and folic acid against DPH teratogenesis.

Possible involvement of beta-endorphin in the deteriorating effect of arginine vasopressin on burn shock in rats

The effect of intracerebroventricular injections of arginine vasopressin (AVP) on burn shock in the rat and its possible mechanism were explored in this study. AVP was administered intraventricularly at 30 min intervals (50 ng) in the burned rats. The arterial pressure and electrocardiogram (ECG) were recorded with a multipurpose polygraph before and after burn. Compared with the control, the MAP of the rats in the AVP group was elevated at the initial stage and fell dramatically at the late stage of burn shock with a higher mortality. The ECG of the rats in the AVP group also displayed earlier changes such as elevation of S-T segment, inversion of T wave, and ventricular fibrillation. These findings suggest an unfavorable role of AVP in burn shock. The plasma, hypothalamic, and anterior and posterior pituitary levels of beta-endorphin 3 hr after burn were measured by radioimmunoassay. The increased level of beta-endorphin in the plasma after AVP treatment indicates the possible involvement of beta-endorphin in the deteriorating effect of AVP on burn shock.

Nonconventional joint-transform correlator

A nonconventional joint-transform correlator (NJTC) is discussed. We show that the shift-invariant property of the usual joint-transform arrangement can be preserved. The advantages of the NJTC are the efficient use of the light source, the use of smaller transform lenses, higher correlation peaks, and a higher carrier fringe frequency.

Differentiation of avian adenovirus type-II strains by restriction endonuclease fingerprinting

Three serologically indistinguishable viruses from the avian adenovirus type-II splenomegaly virus of chickens, marble spleen disease virus of pheasants, and hemorrhagic enteritis virus of turkeys, were analyzed by restriction endonuclease fingerprinting. The DNA from these viruses were examined with 6 restriction endonucleases (Bgl II, EcoRI, HindIII, Hha I, Xho I, and BamHI). Markedly different DNA cleavage patterns were found in these virus isolates with all the 5 enzymes, except with BamHI, suggesting genetic differences between isolates of adenovirus type II. Restriction endonuclease analyses were found to provide a method for distinguishing genetically different, and yet serologically similar, strains of avian adenovirus type II.