Modulation of neuropeptide effects by achatin-I, an Achatina endogenous tetrapeptide

Achatin-I (Gly-D-Phe-L-Ala-L-Asp), an endogenous tetrapeptide in the ganglia of Achatina fulica Férussac, at 3 x 10(-6) M suppressed both the inward current (Iin) of an Achatina giant neurone, PON (periodically oscillating neurone), caused by locally ejected oxytocin, and the outward current (Iout) of v-RCDN (ventral-right cerebral distinct neurone) induced by APGW-amide. Dose (pressure duration)-response studies with oxytocin and APGW-amide showed that their ED50 values were not affected by achatin-I, whereas the Emax values were suppressed. The v-RCDN Iout caused by FMRF-amide was enhanced by achatin-I, but the same current induced by [Ser2]Mytilus inhibitory peptide ([Ser2]MIP) was not affected. Achatin-I suppressed the Iout of TAN (tonically autoactive neurone) caused by acetylcholine, but did not affect the Iin of v-RCDN elicited by acetylcholine. The Iout caused by gamma-aminobutyric acid, threo-beta-hydroxy-L-glutamic acid and dopamine was not affected by achatin-I. It is considered that achatin-I acts as a neuromodulator and has both suppressing and enhancing actions on the effects of various neurotransmitters, including peptides, in Achatina giant neurones.

Anoxia/reoxygenation induces hydroxyl free radical formation in brain microvessels

Isolated rat brain microvessels have been utilized to examine whether they produce hydroxyl free radicals if they are subjected to a 10- to 20-min anoxia period followed by a 40-min reoxygenation period. Hydroxyl free radical flux was assessed utilizing salicylate as a trap. The 2,3- and 2,5-dihydroxybenzoic acids (DHBA) products as well as salicylate in the microvessels were quantitated utilizing high-pressure liquid chromatography (HPLC) with electrochemical and fluorescence detection. The results show that a period of anoxia followed by reoxygenation resulted in an enhanced formation of DHBA compared to the normoxic control microvessels. Addition of superoxide dismutase (SOD) and catalase to the microvessels undergoing anoxia decreased the amount of hydroxyl free radicals trapped, suggesting that superoxide and hydrogen peroxide were produced and excreted from the endothelial cell surfaces and then unless quenched reentered the cells to form hydroxyl free radicals within. The amount of 2,5-DHBA formed closely correlated with the amount of 2,3-DHBA formed, indicating that either product can be used to assess hydroxyl free radical flux in brain microvessels.

Modulatory effects of achatin-I, an Achatina endogenous neuroactive peptide, on responses to 5-hydroxytryptamine

Achatin-I (Gly-D-Phe-L-Ala-L-Asp) was found in the ganglia of an African giant snail (Achatina fulica Férussac), and proposed as an excitatory neurotransmitter of Achatina neurones. At 3 x 10(-6) the peptide markedly enhanced the fast inward current (Iin) of an Achatina neurone type, TAN (tonically autoactive neurone), produced by the pneumatic pressure ejection of 5-HT. This Iin was facilitated immediately by the achatin-I perfusion, and the facilitation decreased gradually even with the peptide present. The dose (duration)-response curves of the TAN fast Iin on pressure ejection in the absence (control) and presence of achatin-I at 3 x 10(-6) M (n = 8) were analyzed as follows. The ED50 (95% confidence limit) were 59.3 ms (13.9-95.3 ms) for the control, and 36.5 ms (19.5-52.6 ms) for achatin-I. The Emax were 1.06 +/- 0.11 nA for the control, and 1.74 +/- 0.26 nA for achatin-I (P < 0.01 for paired data). Among achatin-I derivatives, achatin-II (Gly-L-Phe-L-Ala-L-Asp) enhanced the TAN fast response to 5-HT, but was ten times weaker than achatin-I. [L-Glu4]achatin-I (Gly-D-Phe-L-Ala-L-Glu) and achatin-I amide (Gly-D-Phe-Ala-L-Asp-NH2) had no facilitatory effect. We propose that achatin-I is a neuromodulator as well as a neurotransmitter for Achatina giant neurones.

AJ-2615, a long-acting Ca2+ channel antagonist with a novel structure

AJ-2615, a dihydrodibenzothiepin derivative, at 10(-4) M inhibited the peak ICa amplitude of an identifiable Achatina neurone, PON (periodically oscillating neurone), by nearly a half of the control response 30 min after the start of perfusion (ED50: 0.96 x 10(-4) M). The ICa inhibition was still sustained 30 min after washout, indicating that AJ-2615 has long-lasting activity. The compound inhibited the ICa over a wide range of membrane potentials depolarized by the voltage pulse (Vd), but did not change the membrane potential required to produce the maximal ICa (Vd = 0 mV). The additional decrease in ICa amplitude caused by changing from low-frequency (1/5 min) depolarizing pulses to high-frequency (3/min) depolarizing pulses in the presence of AJ-2615 at 10(-4) M was 39.2 +/- 4.5% (mean+S.E.M.; n = 5), indicating use dependence. The steady state inactivation curves were measured in the presence or absence of AJ-2615 at 10(-4) M with a depolarizing prepulse (Vd = varied, duration = 30 s) followed by a depolarizing test pulse (Vd = +10 mV, duration 80 ms), with 2 ms intervals (n = 3): the ratio of AJ-2615 dissociation constant in the resting Ca2+ channel (Kr) and in the inactivated Ca2+ channel (Ki), Kr/Ki, was calculated to be 9.6:1, indicating voltage dependence.

[The bioavailability of transdermal therapeutic system of timolol]

A matrix-type transdermal therapeutic system of timolol (TTS-timolol) was well prepared. The patch consisted of backing membrane layer, timolol reservoir layer, pressure sensitive adhesive layer and protective layer. A sensitive and reliable HPLC-UV method for the determination of plasma level of timolol in healthy volunteers was developed. Effective therapeutic plasma level of timolol (4 ng/ml) was attained 4 h after application of the timolol patches and was maintained within 32 h while the patch was removed at 24 h. The pharmacokinetic behavior of this transdermal therapeutic system (TTS)-timolol in human showed zero order absorption and well fitted to a one compartment model. The pharmacokinetic parameters are: Tmax = 18.8 h; Cmax = 11.2 ng/ml; AUC = 265.7 ng/ml.h; Vss = 120.0 L; K = 0.084 h-1. In comparison with the results of oral administration of timolol tablets, TTS-timolol possesses some advantages: stable plasma level, long effective time and convenient administration.

Achatin-I, an excitatory neurotransmitter having a D-phenylalanine residue of Achatina giant neurones

The neuroexcitatory peptide isolated from Achatina ganglia was identical to the synthetic Gly-D-Phe-L-Ala-L-Asp with respect to either the bioassay experiments using the Achatina neurones or the instrumental analysis (1H-NMR, SIMS, CD and HPLC). We termed it achatin-I (yield: 50 micrograms from 30,000 animals). Its stereoisomer, Gly-L-Phe-L-Ala-L-Asp, termed achatin-II, was also isolated from the ganglia (yield: 17 micrograms), but this was ineffective on the Achatina neurones. Of the eight possible stereoisomers, only achatin-I markedly showed excitatory effects on the two Achatina neurones, PON and TAN, and [D-Ala3] achatin-I (Gly-D-Phe-D-Ala-L-Asp) had the slight effects. Among the fourteen neurones tested, seven, including the two mentioned above, were excited by achatin-I, whereas no neurone was inhibited. Achatin-I produced an inward current (Iin) with an increase in the membrane conductance (g) under voltage clamp. ED50 of achatin-I for exciting the neurones were 0.20-1.47 x 10(-5) M, and its Emax were 6.33-5.02 nA. Of the achatin-I analogues examined, only the three, Gly-Gly-D-Phe-L-Ala-L-Asp, D-Phe-L-Ala-L-Asp and Gly-D-Phe-L-Ala-L-Asn, produced Iin, but much smaller than that of achatin-I. The equiactive molar ratios (EMRs) of the four effective related peptides (three analogues and a stereoisomer) vs. achatin-I were: 8-60 for Gly-Gly-D-Phe-L-Ala-L-Asp, 200 - > 250 for D-Phe-L-Ala-L-Asp and > 200 for Gly-D-Phe-L-Ala-L-Asn and Gly-D-Phe-D-Ala-L-Asp. The Iin induced by achatin-I was blocked under the /Na+/0-free state, but unaffected under the [Ca2+]-free (replaced with Co2+), [Cl-]0-free or [K+]-enriched (3.0 x) medium, indicating that the Iin is produced by the gNa increase of neuromembrane. We propose that achatin-I having a D-phenylalanine residue is an excitatory neurotransmitter of the Achatina neurones.

APGW-amide as an inhibitory neurotransmitter of Achatina fulica Ferussac

APGWamide (L-Ala-L-Pro-Gly-L-Trp-NH2) was purified from the ganglia of an African giant snail (Achatina fulica Ferussac). This peptide inhibited (hyperpolarized) more than half of the Achatina neurone types tested. This produced an outward current with the membrane conductance increase of RAPN (right anterior pallial neurone) under voltage clamp. The ED50 of the peptide was 6.2 x 10(-6) M (95% confidence limit: 5.0-7.8 x 10(-6) M) and the Emax was 3.9 +/- 0.2 nA. The effects were due to a membrane permeability increase to K+. The peptide is proposed as an inhibitory neurotransmitter of the Achatina neurones.

Oxidative damage to brain proteins, loss of glutamine synthetase activity, and production of free radicals during ischemia/reperfusion-induced injury to gerbil brain

Free radical-mediated oxidative damage has been implicated in tissue injury resulting from ischemia/reperfusion events. Global cortical ischemia/reperfusion injury to Mongolian gerbil brains was produced by transient occlusion of both common carotid arteries. Protein oxidation, as measured by protein carbonyl content, increased significantly during the reperfusion phase that followed 10 min of ischemia. The activity of glutamine synthetase, an enzyme known to be inactivated by metal-catalyzed oxidation reactions, decreased to 65% of control levels after 2 hr of reperfusion that followed 10 min of ischemia. We also report that the free radical spin trap N-tert-butyl-alpha-phenylnitrone [300 mg/kg (body weight)] administered 60 min before ischemia/reperfusion is initiated, partially prevents protein oxidation and protects from loss of glutamine synthetase activity. In addition, we report a N-tert-butyl-alpha-phenylnitrone-dependent nitroxide radical obtained in the lipid fraction of the ischemia/reperfusion-lesioned brains, but there was very little radical present in the comparable sham-operated control brains. These data strengthen the previous observation utilizing in vivo-trapping methods, that free radical flux is increased during the reperfusion phase of the ischemia-lesioned gerbil brain. The loss of glutamine synthetase would be expected to increase the levels of brain L-glutamate. Thus, the oxidative inactivation of glutamine synthetase may be a critical factor in the neurotoxicity produced after cerebral ischemia/reperfusion injury.

Survey of public awareness, understanding, and attitudes toward epilepsy in Henan province, China

The awareness, understanding, and attitudes toward epilepsy in 1,278 men and women were surveyed in Henan, China in 1988. Results showed that 93% had read or heard about epilepsy; 77% knew someone who had epilepsy; 72% had seen someone who was having a seizure; 57% would object to having their children associate with persons with epilepsy in school or at play; 87% would object to having their children marry a person with epilepsy; 53% believed that epileptic persons should not be employed in jobs as other persons are; 16% believed that epilepsy was a form of insanity; 40% did not know the cause of epilepsy; 10% did not know what an epileptic attack was like; and 17% did not know what to recommend if their friends or relatives had epilepsy. The relationship between the responses and the respondents' age, sex, marital status, number of offspring, level of education, occupation, and residence was analyzed. Education reduced the respondent's prejudice against play and employment, but did not change their objection to marriage and appeared to have reinforced their linking epilepsy with insanity. As compared with the surveys conducted in Western countries, our survey showed that awareness of epilepsy in China was greater, if not the same, but the attitudes toward epilepsy were much more negative.

Peroxidation induced changes in synaptosomal transport of dopamine and gamma-aminobutyric acid

The effects of iron-dependent peroxidation on respiration and neurotransmitter transport of brain nerve endings has been studied. Rat brain synaptosomes were peroxidized by exposure to an ADP-Fe/ascorbate system and the protective effect of added Se, Cd, or Zn was investigated with regard to dopamine and gamma-aminobutyric acid (GABA) transport. Peroxidation impaired the respiration of synaptosomes by about 20% and caused a marked increase in dopamine uptake; but in contrast, peroxidation induced a large decrease in synaptosomal uptake of GABA. The increased dopamine transport into synaptosomes was partially prevented by the presence of Zn, Se, or Cd. The presence of Zn, Cd, or Se, in order of decreasing effectiveness, also slowed down ADP-Fe/ascorbate mediated peroxidation of synaptosomes. Peroxidation caused a significant inhibition of veratridine-dependent release of both dopamine and GABA from synaptosomes, but the KCl-dependent release of these neurotransmitters was not effected by peroxidation. These results implicate that peroxidation damage of nerve endings may lead to large changes in neurotransmitter transport thus resulting in an alteration in the function of the central nervous system.

[Long-term result in 61 patients with primary lung cancer treated by pneumonectomy]

Long-term result of 61 patients with primary lung cancer treated by pneumonectomy is reported. There were 55 males and 6 females. The ages ranged from 23 to 62 years with a mean of 47.7. Of these 61 patients, 49 died within ten years after pneumonectomy, 34 of them died of recurrence or metastasis and 8 of cardio-pulmonary diseases. The 5 and 10 year survival rates were 24.1% and 16%, significantly lower than those of 104 patients treated by lobectomy during the same period (42.6% and 33.3%), P less than 0.05). The 5 and 10 year survival rates of left pneumonectomy were statistically higher than those of right pneumonectomy (36.7% and 21.7% versus 8.3% and 9.5%, P less than 0.05). In this paper, the dissection of mediastinal lymph nodes and effect on postoperative cardiopulmonary functions are discussed. The postoperative radiotherapy, to the mediastinum, is advocated because thorough dissection of the mediastinal lymph nodes is very difficult. Sleeve-lobectomy instead of pneumonectomy is indicated for those patients with the tumor located in one lobe and the main bronchus involved.

Hospital pharmacy practice in the People's Republic of China

The practice of hospital pharmacy in the People's Republic of China is described. Since 1949, health care in China has improved. The number of hospitals has increased. While medicines previously were scarce, China now produces approximately 95% of the drugs it needs. China has a long history of traditional medicine; although there are attempts to integrate the concepts of traditional and Western medicine, the practices are still segregated. All hospital pharmacies in China have the responsibilities to guarantee the safe and effective use of drugs within the hospital and to do research. Even though Chinese factories manufacture many pharmaceutical products, the hospital pharmacy must manufacture many more. Hospitals have established Agreed Prescription programs, whereby drugs are manufactured in large batches, repackaged, and distributed to other hospital pharmacies in the area if needed. Quality is assessed chemically and by modern techniques when equipment is available. Most large hospitals now have automated facilities to manufacture sterile solutions. Each hospital has a medical supply committee that supervises the procurement of medical supplies and the reasonable use of drugs. A government resolution mandates that every hospital pharmacy do research. A primary focus of their research is the integration of traditional and Western medicine. Concepts of traditional and Western medicine are taught in separate pharmacy schools. Most pharmacy undergraduate programs are four years, but some schools recently changed to five years. Future challenges for hospital pharmacists in China are to develop the theoretical and technological knowledge of pharmacy, and to expand the scientific and technical information system that is necessary to do research.