Soluble and membrane-bound forms of cytochrome b5 are the products of a single gene in chicken

In order to determine the relationship of the soluble cytochrome b5 found in erythrocytes to the membrane-bound form found in other tissues, a cDNA clone encoding cytochrome b5 in chicken erythrocytes was isolated by using mixed oligonucleotides based on a partial amino acid sequence of the protein. Complete nucleotide sequence identity between the erythrocyte cDNA and the sequence of a cDNA clone of the liver protein suggests that they are transcribed from the same gene. The isolation and structural analysis of genomic clones was also consistent with the presence of only one cytochrome b5 gene in chicken. These results suggest that the formation of soluble erythrocyte cytochrome b5 occurs by proteolytic processing of the membrane-bound form. Thus, previous reports indicating that the carboxyl terminal amino acid residue of the erythrocyte form differs from the corresponding residue of the membrane-bound form may suggest the existence of a novel post-translational modification.

[Pharmacological study of Rubus parvifolius L]

Aqueous extracts of Rubus parvifolius have been proved useful in shortening bleeding time and coagulation time in mice, shortening euglobulinlysis time in rabbits, inhibiting platelet thrombosis in rabbits in vivo, Rubus parvifolius increasing coronary flow in isolated rat heart, preventing rats from pituitrin induced changes of ECG and Rubus parvifolius increasing the tolerance of mice to hypoxia. The toxicity of Rubus parvifolius is small.

[plants of Coptis from Tibet and Yunnan]

In this paper the relationship of Tibetan Huanglian and Yunnan Huanglian with Coptis teeta has been studied. The distribution and taxonomic features of Tibetan Huanglian are just the same as Coptis teeta, but quite different from Yunnan Huanglian. The results reveal that Tibetan Huanglian and Yunnan Huanglian are different in botanical origin.

Induction of tumor necrosis factor by macrophage colony-stimulating factor in vivo

The effect of human urinary colony-stimulating factor (CSF-1) on the production of tumor necrosis factor (TNF) in vivo was assessed. Purified CSF-1 was administered i.v. to rabbits 4 days prior to injection with lipopolysaccharide (LPS). TNF in the serum prepared from rabbits bled 90 min after LPS injection was measured using cytotoxicity assays employing mouse L929 cells and antirabbit TNF monoclonal antibody. The results indicated that CSF-1 was able to induce the production of TNF in vivo and had a synergistic effect with Propionibacterium acnes.

[Preliminary study of traditional Chinese medicine treatment of minimal brain dysfunction: analysis of 100 cases]

This paper reports the clinical treatment of 100 patients with minimal brain dysfunction (MBD), their age ranged from 7-14.2 years, and the average age was 10.5. Patients were divided into TCM and WM group randomly. The TCM group (80 cases) were treated with the therapy of subdueing hyperactivity of the Liver and invigorating the function of the Spleen by using: Bupleurum chinense, Scutellaria baicalensis, Astragalus membranaceus, Codonopsis pilosula, Ligustrum lucidum, Lophatherum gracile and thread of ivory. The WM group (20 cases) were treated with retalin 5-15 mg twice daily. One course of treatment lasted one month, and effects were evaluated after 1-3 courses of treatment. The results were as follows: In the TCM group, 23 cases were cured (clinical symptom and sign disappeared, 10 IQ units were raised in their intelligence, abnormal electroencephalogram was recovered and there was no recurrence during the first six months after recovery). 46 cases were improved (clinical symptom and sign markedly improved, 4 IQ units raised in intelligence and electroencephalogram improved), and 11 cases ineffective. The effective rate was 86.25%. In the WM group, 6 cases were cured, 12 cases improved and 2 cases ineffective, the clinical effective rate being 90.0%. There was no significant difference between the two groups in this study, but, the side-effects of the TCM group was less than the WM group, and the TCM group had more beneficial effects to improve intelligence, enuresis and the black of orbits. The study showed that the Verbal Scale in Wechsler Intelligence Scale for children is one of the indications of diagnosis and evaluating of the curative effect of MBD.

[Antitumor action of lignum sappan]

The aqueous extract of lignum sappan can kill cell lines of HL-60, K562, L929 and Yac-1 at the concentration of 2 microliters/ml. The survival time of mice bearing EAC is increased by 185% (P less than 0.01) by ip 0.2 ml/mouse x 7d. The three-stage sequential test standard can be passed smoothly.

Age and binocular advantage: A VEP assessment

Monocular and binocular visual evoked potentials (VEP's) were recorded in response to contrast-reversing checkerboard patterns of 2 check sizes (14 and 28 min arc) and 2 contrast-reversal rates (1.88 and 7.50 rps) in children (10 and 11-year-olds) and young adults (20 to 30-year-olds). The magnitude of binocular advantage, expressed as the ratio of the binocular to the average monocular response, was assessed by amplitude measurements of the major positive peak. The overall VEP amplitudes were larger for children than for adults across all conditions. The VEP amplitudes for binocularly viewed patterns were also consistently larger than the VEP amplitudes for the monocularly viewed patterns for both age groups. However, when the binocular advantage was expressed as a ratio of binocular to monocular average (MAV), the amplitude difference between the age groups was no longer apparent; although the children's average VEP responses were of a larger amplitude, the binocular advantage remained the same regardless of age.

Sphingosine stimulates cellular proliferation via a protein kinase C-independent pathway

Sphingosine, a metabolite of membrane sphingolipids, is generally considered to be cytotoxic for a variety of cell types. However, we have found that sphingosine at low concentrations stimulates DNA synthesis and acts synergistically with known growth factors to induce proliferation of quiescent Swiss 3T3 fibroblasts. Structurally related analogs of sphingosine, such as N-stearoylsphingosine and other long chain aliphatic amines, had no mitogenic effects, suggesting that sphingosine did not induce nonspecific membrane perturbations. Sphingosine, which has been proposed to be a physiological inhibitor of protein kinase C, also markedly potentiates the mitogenic effect of the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Sphingosine still stimulates DNA synthesis in cells made protein kinase C deficient by prolonged treatment with phorbol ester. At mitogenic concentrations, sphingosine does not bind to protein kinase C as shown by its lack of effect on phorbol dibutyrate binding. Only at higher concentrations, in the cytotoxic range, was there a displacement of phorbol dibutyrate from its cellular-binding sites. In contrast to sphingosine, H-7, a known inhibitor of protein kinase C, inhibited the mitogenic response to TPA and the TPA-induced phosphorylation of the 80 kDa cellular substrate of protein kinase C. Our results suggest that sphingosine may play an important role as a positive regulator of cell growth acting in a fundamentally different, protein kinase C-independent pathway.

Tolerance to diazepam and methyl-beta-carboline-3-carboxylate measured in substantia nigra of benzodiazepine tolerant rats

The spontaneous activity of neurons in the pars reticulata of substantia nigra (SNpr) was studied in chloral hydrate anesthetized rats. As a function of dose, intravenous diazepam decreased, and methyl-beta-carboline-3-carboxylate (beta CCM) increased discharge frequency. Two days after terminating a one week treatment with flurazepam (FZP), both diazepam and beta CCM showed decreased ability to alter SNpr neuronal activity. Neither residual FZP nor down-regulation of benzodiazepine receptors can account for these results. In contrast, behavioral testing revealed no change in the ability of i.v. beta CCM to cause convulsions, suggesting that sites other than the SNpr are of prime importance in expressing the convulsant actions of systemically injected beta CCM.

A model for tumor cell killing by topoisomerase poisons

Our model proposes that topoisomerase-targeting antitumor drugs form reversible drug-enzyme-DNA complexes that collide with the DNA and RNA synthesis machineries. On collision, the complexes lose their reversibility, and generate lethal double-strand DNA breaks. Further investigations of topoisomerase action will allow this model to be refined, and may ultimately lead to the development of more effective anticancer drugs.

[Citation analysis of Acta Pharmacologica Sinica 1984-1989]

Citation analysis was made bibliometrically on the collection and dispersion of the references in Acta Pharmacologica Sinica 1984-1989. Core periodicals were sorted out: 31 in foreign languages and 6 in Chinese. Suggestions are proposed to the information services.

Effects of contralateral superior laryngeal nerve stimulation on dorsal medullary inspiratory neurons

The effects of superior laryngeal nerve (SLN) stimulation on phrenic (PHR) nerve activity and on activity of dorsal respiratory group (DRG) inspiratory (I) neurons contralateral to the stimulus were examined in decerebrate, paralyzed cats. Stimulation caused bilateral PHR suppression followed by recovery at ca. 30 ms. Most DRG neurons (70%) contralateral to the stimulus were inhibited, but average onset of inhibition lagged that of PHR suppression. This contrasts sharply with the observation in an earlier study that inhibition of ipsilateral I neurons on the average preceded PHR suppression. The remaining neurons (30%) were not inhibited. Only 22% of contralateral neurons were excited by SLN stimulation, in contrast to 52% of ipsilateral neurons. Thus, contralateral DRG I neurons do not mediate the onset of bilateral PHR suppression by SLN stimulation and are probably inhibited through a longer pathway than that for the ipsilateral unit responses.

[Effect of injections of huoxue huayu on hemodynamics of the canine small intestine]

The effect of Huoxue Huayu injection(HHI) on hemodynamics of canine small intestine was investigated in 25 healthy mongrel dogs. SMA was used for intestinal blood flow measurement with an electronic magnetic flowmeter. After measuring the arterial and venous oxygen saturation the intestinal oxygen consumption and vascular resistance were calculated. In the control group (n = 8) the dog was infused with normal saline (NS) and in the experimental group (n = 9) HHI was used with the same dosage of 3.75 ml per kg body weight per hour. Small molecular weight dextran (SMD) was administered in the third group as a known vasodilator agent. The results showed no effect of NS on intestinal hemodynamics. At the periods of 20, 40 and 60 minutes following HHI the mean values of intestinal blood flow were 291.22 +/- 98.12, 307.56 +/- 106.64 and 283.33 +/- 96.84 ml.min-1 respectively. They were statistically different against the premedication values (181.56 +/- 62.38 ml.min-1). The values of intestinal oxygen consumption at the corresponding periods were 6.97 +/- 3.62, 6.97 +/- 3.80 and 7.11 +/- 3.04 ml.min-1. They were markedly greater than those before HHI (4.85 +/- 2.23 ml.min-1). Analysis proved that blood flow and vascular resistance had a dependent relationship. HHI was marked by stronger effect than SMD when used in smaller dosage. It was believed that both the increase of blood flow and oxygen consumption might be an important pharmacological basis of the application of Huoxue Huayu principle in the treatment of acute abdominal diseases.

[Comparison of effect in the change of respiration by stimulating three trigeminal subnucleus]

Experiments were performed on 31 rabbits. After recovery from surgical anesthesia the change of respiration were observed in various experimental conditions, under which original nucleus of trigemini (ONT), terminal nucleus of trigemini (TNT), spinal tractus nucleus of trigemini (SNT) were respectively stimulated by an electrical current (EC) or monosodium glutamate (MSG) or lidocaine (LID). Because SNT had a longitudinal long shape, three different sections of SNT were selected as stimulating points respectively, namely rostral point (A2.33 mm), middle point (AP0 mm) and caudal point P1.9 mm). Phrenic nerve discharge and its integrated curve, PCO2 and blood pressure were recorded by a RM-6000 polygraph. The results indicated that the stimulations of EC and MSG to SNT and TNT enhanced respiratory activity obviously. Stimulation of EC and MSG to ONT caused much less enhancement of respiration. Microinjection of LID to TNT and ONT decreased respiratory activity, but microinjection of LID to SNT increased. The present experiment concluded that stimulation of SNT and TNT could cause significant change in respiration.

Abnormal processing of multiple proteins in Alzheimer disease

Cerebrovascular amyloid is the main constituent of the perivascular and neuritic plaques typical of Alzheimer disease, whereas neurofilaments and microtubule-associated tau protein have been considered primary contributors to the formation of the characteristic Alzheimer tangles. Plaques and tangles and their constituents have at times been ascribed a role in pathogenesis of the disease. Normally, neurofilaments become phosphorylated only upon axonal entry. In many neurologic disorders, neurofilament phosphorylation, as detected by any of the available monoclonal antibodies (mAbs) to neurofilament phosphorylated epitopes is shifted from an axonal to a cell-body location. An exception is provided by Alzheimer disease, where tangles (which are neuronal cell-body-derived structures) exhibit only one phosphorylated epitope. However, the very presence of neurofilaments in tangles and plaques has been questioned because of a reported cross-reaction of mAbs to phosphorylated neurofilaments with tau protein. On reinvestigating this cross-reactivity we found that four of five mAbs to phosphorylated neurofilaments and four of five mAbs to nonphosphorylated neurofilaments failed to react with tau protein. A fifth mAb (07-5) to phosphorylated neurofilament cross-reacted with partially denatured tau protein at an affinity 1/1700th of that for denatured neurofilaments; nondenatured tau protein in tissue sections did not cross-react. A fifth mAb (02-40) to nonphosphorylated neurofilament also cross-reacted weakly. In Alzheimer disease normal-appearing axons were revealed with all the mAbs to phosphorylated neurofilaments, but tangles were revealed with only one of them (mAb 07-5). mAb to tau protein did not stain or did so indistinctly. Four of five mAbs to nonphosphorylated neurofilaments failed to reveal axons. Upon dephosphorylation of tissue, staining by mAbs to phosphorylated neurofilaments disappeared, and axons were revealed with the mAb to tau protein and all mAbs to the nonphosphorylated neurofilaments. Tangles became stained with tau mAb and one mAb to the nonphosphorylated neurofilaments (mAb 10-1). Quantitative evaluation of immunocytochemical staining intensities and immunoblot cross-reactivity showed that neurofilaments are, indeed, constituents of tangles--apparently exceeding the concentration of tau protein 17-fold. Contribution of both conformation and primary structure to IgG specificity may explain the lack of any cross-reaction of mAbs to neurofilaments with tau protein in intact tissue and the appearance of cross-reaction in immunoblots where conformation specificity may be largely lost. The present data extend earlier findings of abnormal processing of neurofilaments and tau protein in Alzheimer disease and, together with reported abnormal processing of cerebrovascular amyloid beta-protein, suggest that inhibition of the processing of multiple proteins is basic to the pathogenesis of Alzheimer disease, whereas formation of plaques and tangles could be merely the most striking histologic result.

Recognition and management of Budd-Chiari syndrome: report of one hundred cases

Budd-Chiari syndrome is an unusual form of portal hypertension caused by occlusion of the hepatic venous outflow, and it is often confused with portal hypertension caused by liver cirrhosis. Its prognosis is poor, and optimal therapy remains to be established. This is a report of 100 confirmed cases of this syndrome treated from December 1982 to March 1988 at two vascular centers in China. Sixty-two male and 38 female patients, 15 to 62 years of age (mean age, 32.6 years) were treated. Seventy-six patients had intractable ascites, 56 had esophageal varices, and 22 had upper gastrointestinal bleeding. There were 37 cases of membranous obstruction, 57 cases of occlusion of the inferior vena cava above the confluence of the hepatic veins, and 6 cases of occlusion of the hepatic veins. Eighty-one patients were operated on. Operative mortality rate was 8.6% (7/81). Follow-up from 2 to 66 months revealed that 58 of the patients operated on (72%) had good results, whereas 11 of 19 (58%) patients treated nonoperatively died within 2 months after admission. On the basis of these data we conclude that the operative procedure must be tailored to the cause and underlying pathologic characteristics. Mesoatrial shunting is the operation of choice for patients with occlusion of the retrohepatic inferior vena cava and hepatic veins, and inferior vena cava--atrial shunting is the operation of choice for patients with occlusion of the inferior vena cava and patency of the hepatic veins. Membranotomy is used for patients with inferior vena cava webbing, and mesocaval shunting is used for patients with intrahepatic venous occlusion only.(ABSTRACT TRUNCATED AT 250 WORDS)

Seeding of autogenous endothelial cells to inner surface of small-caliber dacron vascular prostheses. An experimental study on canines

We presented the experimental results of endothelial cells (EC) seeding in small caliber interpositional dacron grafts of canine carotid arteries. Six weeks after surgery, 9 (56.25%) seeded, and 6 (37.5%) control grafts remained patent. The mean thrombus-free surface area was 83.4% in the seeded and 62% in the controls. The mean volume of thrombus was 74 mg and 218 mg respectively (P less than 0.05). Morphologically, the endothelial layer extension on the graft from the host artery was less than 1 cm. Scanning electron microscopy revealed that a thin luminal layer was composed of flat polygonal cells at the seeded midgrafts, and that fibrous tissues were covered with numerous platelets, fibrin, and blood cells at the unseeded midgrafts. Transmission electron microscopy demonstrated that cells on the seeded midgrafts were characterized by endothelial cells. We conclude that endothelial cells seeding could improve the performance of small-caliber dacron prostheses.

Template supercoiling during ATP-dependent DNA helix tracking: studies with simian virus 40 large tumor antigen

Incubation of topologically relaxed plasmid DNA with simian virus 40 (SV40) large tumor antigen (T antigen), ATP, and eubacterial DNA topoisomerase I resulted in the formation of highly positively supercoiled DNA. Eukaryotic DNA topoisomerase I could not substitute for eubacterial DNA topoisomerase 1 in this reaction. Furthermore, the addition of eukaryotic topoisomerase I to a preincubated reaction mixture containing both T antigen and eubacterial topoisomerase I caused rapid relaxation of the positively supercoiled DNA. These results suggest that SV40 T antigen can introduce topoisomerase-relaxable supercoils into DNA in a reaction coupled to ATP hydrolysis. We interpret the observed T antigen supercoiling reaction in terms of a recently proposed twin-supercoiled-domain model that describes the mechanics of DNA helix-tracking processes. According to this model positive and negative supercoils are generated ahead of and behind the moving SV40 T antigen, respectively. The preferential relaxation of negative supercoils by eubacterial DNA topoisomerase I explains the accumulation of positive supercoils in the DNA template. The supercoiling assay using DNA conformation-specific eubacterial DNA topoisomerase I may be of general use for the detection of ATP-dependent DNA helix-tracking proteins.

Dorsal medullary inspiratory neurons: effects of superior laryngeal afferent stimulation

In decerebrate paralyzed cats ventilated with a cycle-triggered pump, we examined the responses of inspiratory (I) neurons in the region of the ventrolateral nucleus tractus solitarius (NTS) to single electrical stimuli delivered to the ipsilateral superior laryngeal nerve (SLN). Sixty-five I neurons were classified as: I(-), I(0), I(+, early), I(+, late) or I(other) on the basis of responses to lung inflation, and as I(bulbophrenic) or I(non-bulbophrenic) on the basis of evidence of an excitatory projection to the contralateral phrenic motoneuron pool. The peristimulus histograms of contralateral phrenic activity showed an early peak of excitation with average latency of 4.9 +/- 0.1 ms (mean +/- S.E.M.), followed by depression at 7.3 +/- 0.2 ms, start of recovery from depression at 22.7 +/- 1.0 ms, and recovery to control levels at 28.4 +/- 1.1 ms. The peristimulus histograms of ipsilateral I unit activity showed an initial excitation (latency 2.9 +/- 0.3 ms), followed by spiking silence (latency 6.0 +/- 0.6 ms) and recovery to control discharge frequency at 38.8 +/- 3.6 ms. This time of inhibition was significantly longer than the time of phrenic depression, suggesting that other bulbophrenic excitatory projections are able to rapidly compensate for decreased NTS output. Subgroups of I neurons, as classified by lung inflation tests, did not differ significantly with respect to these timing variables. In contrast, latencies of excitation for I(bulbophrenic) neurons were significantly less than for I(non-bulbophrenic) neurons.

Enhancement of nitrocaphane cytotoxicity by hyperthermia in vitro

HEp-2 cells were treated with hyperthermia (39-44 degrees C) and nitrocaphane (NC) at various time intervals. A 1 h exposure to 39 degrees C and 41 degrees C was non-lethal to cells, but it did potentiate the cell killing of NC (1.0 micrograms/ml). It was further shown that the sequence between heat and the drug can affect cell survival. Cell killing effect was decreased when heat was given before or after administration of drug. In contrast the simultaneous administration of these two modalities was synergistic. Maximal thermotolerance of HEp-2 cells was developed using an 8-h interval at 37 degrees C between the cell exposures to two equal thermal doses (44 degrees C, 30 min). HEp-2 cells became thermotolerant when preheated for 30 min at 44 degrees C followed by a 10-h interval at 37 degrees C. The thermotolerant cells showed resistance to subsequent heat at 44 degrees C (D0 = 2.26 h, control D0 = 0.38 h), to subsequent NC treatment, and to heat combined with NC. However, in the thermotolerant cells, cytotoxicity of NC was still enhanced by hyperthermia.

[New taxa of coptis from China]

The rhizomes of Coptis, known as Huang-Lian, are commonly used as traditional Chinese drugs. Two new species, viz., Coptis linearisepala, C. gulinensis and a new variety, viz., C. chinensis var. unguiculata are reported and the descriptions of the new species and new variety are presented in the present paper.

[The relationship between DNA content in cervical carcinoma cell and the clinicopathological features]

Nuclear DNA content was determined by flow cytometry in biopsy samples taken from cervical carcinomas of 33 patients. Aneuploid DNA content was found in 24 cases (72.7%). The relationship between DNA content of carcinoma cells and the clinicopathological features was investigated. Carcinomas with aneuploid DNA content were clinically more advanced and histologically poorly differentiated as compared with those with diploid DNA content. DNA content was found neither correlated with the patient's age nor with the growing type of the tumor; and analysis of DNA content by flow cytometry was considered helpful in evaluating tumor malignancy, efficacy of treatment and prognosis.

Injection of benzodiazepines but not GABA or muscimol into pars reticulata substantia nigra suppresses pentylenetetrazol seizures

The substantia nigra pars reticulata (SNpr), a brain area rich in GABA and benzodiazepine receptors, is thought to be involved in the regulation of seizure activity. It has been shown to be a site of anticonvulsant action of substances that affect GABA transmission. The anti-pentylenetetrazol (PTZ) activities of intranigral of muscimol, a GABAA receptor agonist; two benzodiazepines, midazolam and flurazepam; and GABA were examined. Microinjection of a wide dose range of both GABA and muscimol into the SNpr failed to show anti-PTZ seizure activity. Intranigral injections of midazolam and flurazepam showed clear, dose-dependent anti-PTZ effects. Ro15-1788, a benzodiazepine receptor antagonist, reversed the anticonvulsant effects of midazolam when both were infused intranigrally. Intranigral infusion of muscimol or flurazepam protected rats from bicuculline-induced tonic seizures. The results suggest that the anti-PTZ effects of benzodiazepines in SNpr might not be mediated through GABAA receptors. Another possibility is that nigral neurons bearing GABAA receptors functionally linked to benzodiazepine sites may not be representative of the whole population of nigral neurons inhibited by GABA agonists. This could result in different patterns of inhibition of nigral efferent activity by GABAA agonists and benzodiazepines.

Mechanisms for the stimulation of prostanoid synthesis by cyclosporine and bacterial lipopolysaccharide

Both cyclosporine and bacterial lipopolysaccharide enhance prostanoid synthesis and regulate the immune response. This study was designed to establish whether these agents affect prostanoid synthesis by common or different mechanisms. CsA and LPS stimulate prostanoid synthesis both in human monocytes and smooth muscle cells from guinea pig aorta. Only LPS stimulates synthesis in the presence of exogenous arachidonic acid. Dexamethasone totally blocks CsA but only partially inhibits LPS. CsA and LPS both enhance the release of labeled metabolites from cells labeled with arachidonic acid, but indomethacin only blocks the effect of LPS. CsA and the releasing agent calcium ionophore (A23187) both increase PGE2 and PGI2 synthesis without changing their relative concentrations, cause the release of free arachidonic acid, and lead to the formation of new metabolites that are not products of cyclooxygenase activity. Preincubation with either CsA or A23187 and a subsequent wash deplete the arachidonic acid pool available for prostanoid synthesis. Thus, A23187 and CsA have very similar effects on arachidonic acid metabolism. In contrast, LPS increases PGE2 and PGI2 synthesis and alters their relative concentrations, diminishes the relative concentration of free arachidonic acid, and enhances the formation of new metabolites that are products of cyclooxygenase activity. These differences are explained by mechanisms in which CsA promotes prostanoid synthesis through arachidonic acid release, and LPS promotes prostanoid synthesis through increased cyclooxygenase activity.

Synthesis of 4% Glu-containing Val1 and Ile1-polypentapeptides: model protein systems for demonstrating mechanochemical coupling

The synthesis of 4% Glu-polypentapeptide (PPP) (i.e., 4 Glu residues per 100 amino acid residues) and 4% Glu-Ile1-PPP, in which Val1 is substituted by a more hydrophobic Ile residue, is carried out by copolymerizing the p-nitrophenyl-active esters of GE(OMe)GVP and GE(OMe)GIP with their parent pentamers GVGVP and GVGIP in 1:4 ratios, respectively. After removal of the methyl ester on the side chain of Glu, these polymers exhibited a remarkable pH dependence of the temperature for their inverse temperature transitions, which are followed as turbidity development at 300 nm. On gamma-irradiation crosslinking, the elastomeric bands obtained exhibited a pH-mediated contraction and relaxation. Thus, for the first time, mechanochemical coupling is demonstrated in a synthetic polypeptide system. That the basic mechanism involves the hydrophobic effect (chemical modulation of an inverse temperature transition) and not ion-ion electrostatic repulsion is also discussed.

[Study on toxicological mechanism of moniliformin]

A mycotoxin was extracted and purified from a strain of Fusarium moniliforme var. subglutinans isolated from mouldy corn seeds harvested in a serious Keshan disease region in Shaanxi Province. The purification procedure involves water extraction, ion exchange chromatography, desalination and crystallization. Its UV spectrum, IR spectrum and NMR are identical with that of the moniliformin. The toxin is highly toxic to young Beijing ducklings. The electrocardiogram (ECG) of the duckling was changed immediately after feeding with moniliformin. The cardiac muscle cells of Beijing ducklings were injured by the toxin. Toxicity may be alleviated to certain extent by applying adequate dosage of Selenium (3.18 X 10(-10) mol/L of H2SeO4) prior to moniliformin treatment. The permeability of the cardic muscle cells of the rats and young ducklings was damaged posterior to the injection of the toxin as tested by extracellular marcromolecular tracer (HRP) method. The relationship between moniliformin and Keshan disease was discussed. We consider that the moniliformin may be the causal agent of the disease.

[Quantitative determination of 5 alkaloids in plants of Coptis from China]

Quantitative determination of berberine, coptisine, palmatine, jatrorrhizine and epiberberine in Coptis chinensis, C. deltoidea, C. teetoides, C. omeiensis, C. chinensis var. brevisepala, C. linearisepala, C. gulinensis, C. chinensis var. unguiculata, C. teeta and 5 different samples of C. chinensis was made by thin layer chromatography-densitometry.

Role of beta-receptor in the radix Angelicae sinensis attenuated hypoxic pulmonary hypertension in rats

Acute pulmonary hypertension was caused by inhalation of 5% O2 in rats. Pulmonary vascular resistance (PVR) increased, but heart rate (HR), cardiac output (CO) and carotid arterial pressure (CAP) were not obviously changed. After an intravenous administration of Radix Angelicae sinensis, the acute pulmonary hypertension induced by inhalation of 5% O2 could be attenuated, but this effect disappeared if propranolol was given before Radix Angelicae sinensis. In chronic experiments, the same results were obtained, but the protective effect of Radix Angelicae sinensis on heart function was not influenced by propranolol. It is suggested that Radix Angelicae sinensis might play a role by stimulating the beta 2-receptor in the prevention of acute and chronic hypoxic pulmonary hypertension. However, prevention of hypertrophy of the right ventricle and enhancement of heart function in chronic hypoxic rats might not be attributed to the beta 1-receptor in the heart.

Human DNA topoisomerase I is encoded by a single-copy gene that maps to chromosome region 20q12-13.2

cDNA clones of the human TOP1 gene encoding DNA topoisomerase I (EC 5.99.1.2) have been obtained by immunochemical screening of phage lambda libraries expressing human cDNA segments, using rabbit antibodies raised against purified HeLa DNA topoisomerase I. Hybridization patterns between the cloned cDNA sequences and human cellular DNA and cytoplasmic mRNAs indicate that human TOP1 is a single-copy gene. The chromosomal location of the gene has been mapped to the long arm of chromosome 20, in the region q12-13.2, by hybridization of a radioactively labeled TOP1 cDNA probe to human metaphase chromosomes and to a panel of rodent-human somatic hybrids retaining overlapping subsets of human chromosomes.