The cost of coverage: rural health insurance in China

China has undergone great economic and social change since 1978 with far reaching implications for the health care system and ultimately for the health status of the population. The Chinese Medical Reform of the 1980s made cost recovery a primary objective. The urban population is mostly protected by generous government health insurance. A high share government budget is allocated to urban health care. Rural cooperative health insurance reached a peak in the mid-1970s when 90% of the rural population were covered. In the 1980s rural cooperative health insurance collapsed and present coverage is less than 8%. The decline has been accompanied by reports of growing equity problems in the financing of and access to health care. This article is the first in a four-year study of the impact on equity of the changes in Chinese health care financing. The article examines the relationship between rural cooperative health insurance as the explanatory variable and health care expenditure, curative vs. preventive expenditure and tertiary curative care expenditure as dependent variables using a natural experimental design with a 'twin' county as a control. The findings support the hypothesis that cooperative health insurance will induce higher growth of health care expenditure. The findings also support the hypothesis that cooperative health insurance will lead to a shift from preventive medicine to curative medicine and to a higher level of tertiary curative care expenditure. The empirical evidence from the Chinese counties is contradicting World Bank health financing policies.

Growth rate regulation of 4.5 S RNA and M1 RNA the catalytic subunit of Escherichia coli RNase P

We have studied the expression of 4.5 S RNA and M1 RNA, the catalytic subunit of Escherchia coli RNase P, under various growth conditions. Both RNA species increase in abundance as a function of growth rate. There are roughly 450 molecules of 4.5 S RNA and 80 molecules of M1 RNA per cell at 0.4 doubling per hour, and this is increased to 5300 and 1060 molecules per cell, respectively, at 2.7 doublings per hour. Deletion of both relA and spoT, the two genes that are responsible for synthesis of ppGpp, does not affect the rate of synthesis of either RNA species. However, deletion of fis renders the expression of 4.5 S RNA independent of growth rate, but has little effect on the expression of M1 RNA. These data suggest that the expression of both 4.5 S RNA and M1 RNA genes are growth-rate regulated, but not through the same mechanism. The growth-rate dependent accumulation of 4.5 S RNA depends on FIS-mediated trans-activation, whereas that of M1 RNA is not governed by ppGpp or by FIS.

Co-variation of tRNA abundance and codon usage in Escherichia coli at different growth rates

We have used two-dimensional polyacrylamide gel electrophoresis to fractionate tRNAs from Escherichia coli. A sufficiently high degree of resolution was obtained for 44 out of 46 tRNA species in E. coli to be resolved into individual electrophoretic components. These isolated components were identified by hybridization to tRNA-specific oligonucleotide probes. Systematic measurements of the abundance of each individual tRNA isoacceptor in E. coli, grown at rates varying from 0.4 to 2.5 doublings per hour, were made with the aid of this electrophoretic protocol. We find that there is a biased distribution of the tRNA abundance at all growth rates, and that this can be roughly correlated with the values of codon frequencies in the mRNA pools calculated for bacteria growing at different rates. The tRNA species cognate to abundant codons increase in concentration as the growth rate increases but not as dramatically as might be anticipated. The levels of most of the tRNA isoacceptors cognate to less abundant codons remain unchanged with increasing growth rates. The result of these changes in tRNA abundance is that the relative increase in the amounts of major tRNA species in the bacteria growing at the fastest growth rates is more modest than previous estimates from this laboratory suggested. Furthermore, a systematic error in previous estimates of ribosomal RNA content of the bacteria has been detected. This will account for the quantitative discrepancies between the previous and the present data for tRNA abundance.

Bacterial growth inhibition by overproduction of protein

Multicopy plasmids that have been engineered to produce large quantities of a single gratuitous (non-functional, non-toxic) protein are often problematic. When fully induced, these engineered constructions produce very sick bacteria. The reasons for this may be found in the physiology of wild-type laboratory strains that have been selected to grow at maximum rates with optimal quantities of their proteins. Such bacteria apparently experience the accumulation of gratuitous proteins as an internal shift down and they respond to this with a starvation response. Unlike the shift down associated with a change of growth media, the production of large quantities of gratuitous protein is not associated with a new pre-programmed steady-state of balanced growth. Consequently, the starvation response continues until the bacteria commit suicide by, among other things, destroying their ribosomes.

[Obesity-hypoventilation syndrome]

5 cases with obesity-hypoventilaion syndrome were reported. The clinical manifestations were obesity, palpitation, dyspnea, lethargy, cyanosis, distention of cervical vein, edema, enlargement of liver and hypertension. All of them were initially diagnosed as chronic bronchitis or heart diseases. Pulmonary function test showed restrictive ventilative defect and hypercapnia with hypoxemia. Mouth oclusion pressure at 0.1 second was higher than the normal value. The response to CO2 was decreased. Hypertrophy of right heart was shown in ECG and X-ray film improvement in symptoms and blood gases analyses were found to be associated with body weight decrease in a follow up period of one year.

Endothelium-dependent hyperpolarization of vascular smooth muscle: role for a non-nitric oxide synthase product

There is now a considerable evidence that indicates that there is non-NO/prostanoid mediated vasodilation/hyperpolarization mechanism in a variety of blood vessels from different species. It is argued that a factor, EDHF, is responsible for mediating these cellular events and, like NO, EDHF is synthesized and released, in a Ca(2+)-dependent manner, from endothelial cells and activates vascular K+ channel(s) with the predominant evidence suggesting K(Ca) (iberiotoxin and/or apamin sensitive) though this remains to be absolutely confirmed. A number of studies also indicate that a cytochrome P-450 metabolite of arachidonic acid, namely an epoxyeicosatrienoic acid, may serve as the chemical messenger between endothelial and vascular smooth muscle cells. Evidence confirming that there is chemical transmission between endothelial and vascular smooth muscle cells is, however, minimal. Although significant progress has been recently made, much needs to be discovered concerning the nature, synthesis, release, vascular effects as well as the role of EDHF in normal and diseased vascular tissue.

[Effect of RII on the biological properties of human nasopharyngeal carcinoma cell lines]

N(4-hydroxycarbophenyl) retinamide (RII) is a new synthetic analog of retinoids with low toxicity. Its effect on the biological properties associated with tumor malignant behavior of human nasopharyngeal carcinoma cell lines (HNCs), including CNE-2Z parent cell lines and their variants L2, H2, L4 was studied. RII (10(-5) mol/L) caused detectable morphologic differentiation of HNCs. It inhibited growth of HNCs in vitro and decreased ability of these cells to penetrate matrigel-coated filters by using a reconstituted basement membrane invasion assay. These results suggested that RII might be a kind of useful anticancer drug.

[Apoptosis of tumor cells in lectin-dependent lymphokine-activated killer cell-mediated cytotoxicity]

By using DNA electrophoresis and propidium iodide (PI) staining flow cytometry (FACS) analysis, we studied the mechanisms of lymphokine-activated killer (LAK) cell-mediated cytotoxicity. In the presence of pokeweed mitogen (PWM), human LAK cells induced DNA fragmentation of two leukemic cell lines (U937 cells and Raji cells) and two solid tumor cell lines (SW1116 cells and Hep-2 cells), a hallmark of apoptosis. The reactions were carried out at the effector/target ratio of 1:1 and in 4 hr coculture. Pretreatment with RNA and protein synthesis inhibitors (actinomycin D and cycloheximide) did not prevent the target cells from apoptosis. As the TNF-resistant tumor cell lines such as SW1116 cells and Raji cells were also triggered to apoptosis, other factors than TNF would play the role. DNA-PI staining FACS analysis also suggested that a part of LAK cells underwent apoptosis to some extent during incubation with target cells. The results provide a new way to investigate the mechanisms of cytotoxicity of LAK cells and to enhance the efficacy of adoptive tumor therapy with LAK cells.

Determination of human immunodeficiency virus RNA in plasma and cellular viral DNA genotypic zidovudine resistance and viral load during zidovudine-didanosine combination therapy

Eleven human immunodeficiency virus (HIV)-infected subjects on long-term zidovudine (ZDV) therapy had didanosine (ddI) added to their antiretroviral regimen. HIV RNA in plasma was quantitated by branched-DNA signal amplification assay. Peripheral blood mononuclear cell (PBMC) HIV viral DNA was quantitated by PCR. The relative amounts of wild-type (WT) sequence, ddI resistance-associated codon changes (reverse transcriptase [RT] gene codon 65 K-->R [RT K65R], RT 174V, RT I135K/T/V, and RT M184I/V), and ZDV resistance-associated codon change (RT T215Y/F) from HIV RNA in plasma and RT T215Y/F from PBMC viral DNA were determined by differential hybridization of PCR products from 10 of 11 subjects. All subjects had evidence of RT T215Y/F mutation in both RNA in plasma and PBMC DNA at baseline. Subjects with a mixture of WT and RT T215Y/F HIV RNA in plasma at baseline demonstrated a decline in RNA levels in plasma after the addition of ddI. However, after 6 months of ZDV-ddI therapy, WT HIV RNA in plasma was undetectable in all subjects who had demonstrated a mixture at baseline. Subjects with only RT T215Y/F RNA present in plasma at baseline remained so and demonstrated no decline in RNA levels in plasma. In all subjects, no significant changes in PBMC DNA viral load and RT T215Y/F or WT levels were seen. HIV RNA in plasma demonstrated a significantly higher RT T215Y/F mutant/WT ratio than that of PBMC viral DNA, both at baseline and after ZDV-ddI combination therapy in all subjects. No subjects developed mutations associated with ddI resistance at codons 65, 74, 135, and 184 during this study. This study suggests that determination of relative amounts of RT T215Y/F and WT species from HIV RNA in plasma at baseline may be predictive of virologic response during ZDV-ddI combination therapy.

Ribosome mutants with altered accuracy translate with reduced processivity

We have determined whether or not there is a correlation between the accuracy of tRNA selection and the processivity of translation by mutant ribosomes. In our assay the estimation of processivity was made from a system in which transcription is dependent on T7 RNA polymerase in order to eliminate the influence of transcriptional polarity on our measurements. We found that the processivity of translation is reciprocally correlated to the degree with which mutant ribosomes restrict nonsense suppression events. This is observed when transcription is from both T7 RNA polymerase and Escherichia coli RNA polymerase. In other words, we have confirmed the expected correlation between increased accuracy of tRNA selection and decreased processivity of translation. No such monotonic correlation was obtained with ribosome ambiguity (ram) mutants, though all of these were less processive than wild-type ribosomes. In addition, streptomycin was found to simultaneously stimulate tRNA selection errors and processivity of translation for a mutant that is partially dependent on streptomycin. These data suggest that the growth rates of ribosome mutants are significantly decreased by the degree to which their processivity in translation is affected. Furthermore, we suggest that streptomycin dependence is a phenomenon reflecting the interplay of the restrictive mutation and antibiotic on the processivity of translation.

Inhibitory effects of 2-[(diethylamino)acetyl]-1,2,3,4-tetrahydro-6, 7-dimethoxyl-1-[1'-(6"-methoxy-2"-naphthalenyl)ethyl]-isoquinoline on isolated guinea pig papillary muscle and heart atrium

AIM

To investigate the cardiac actions of 2-[(diethylamino)acetyl]-1,2,3,4-tetrahydro-6, 7-dimethoxyl-1-[1'-(6"-methoxy-2"-naphthalenyl) ethyl]-isoquinoline (CPU57) by comparison with nifedipine and focus on its mechanism of actions.

METHOD

The following were measured and recorded: 1) the rate and contraction of spontaneous beating of the guinea pigs right heart atrium, 2) the isometric tension of the electrically stimulated left heart atrium and the right papillary muscles.

RESULTS

CPU57 had negative inotropic and negative chronotropic actions in isolated heart of guinea pigs as the typical calcium antagonist, nifedipine. However, CPU57 0.01-100 mumol.L(-1) produced less cardiac inhibitory potency than nifedipine and had much stronger negative inotropic action than negative chronotropic action. The decrease in external CaCl2 concentration from 1.5 to 0.3 mmol.L(-1) or increase to 7.5 mmol.L(-1), potentiated or reduced respectively, the inhibitory action of CPU57 on the contraction in paced left heart atrium in normal CaCl2 solution. CPU57 1-10 mumol.L(-1) also inhibited contractile response to CaCl2 in paced left heart atrium with pD2' value of 4.77.

CONCLUSION

CPU57 has calcium antagonism on the heart of guinea pigs.

Central cardiovascular effects of CPU-23, a substituted tetrahydroisoquinoline, in rats

The cardiovascular effects of intracerebroventricular (i.c.v.) injections of low doses of CPU-23, a substituted tetrahydroisoquinoline, were investigated and compared with those of nifedipine in pentobarbital-anaesthetized Sprague-Dawley rats. CPU-23, in doses of 0.2 to 0.5 mg/kg (i.c.v.), which did not elicit any significant cardiovascular responses when injected intravenously, caused a clear-cut and long-lasting decrease of mean arterial pressure (MAP) and heart rate (HR) in a dose-dependent manner. The effects of CPU-23, in a dose of 0.05 mg/kg, were similar to those of nifedipine, a prototype L-type calcium antagonist. The hypotensive effects of CPU-23 were significantly attenuated by bilateral cervical vagotomy. The results strongly suggest that a central component may be involved in the cardiovascular effects of CPU-23 and that dihydropyridine receptor sites in the brain may be involved in the central control of cardiovascular functions.

Gratuitous overexpression of genes in Escherichia coli leads to growth inhibition and ribosome destruction

We attempted to test the idea that the relative abundance of each individual tRNA isoacceptor in Escherichia coli can be altered by varying its cognate codon concentration. In order to change the overall codon composition of the messenger pool, we have expressed in E. coli lacZ with the aid of T7 RNA polymerase so that their respective gene products individually accounted for 30% of the total bacterial protein. Unexpectedly, the maximum expression of either test gene has no specific effect on the relative rates of synthesis of the tRNA species that we studied. Instead, we find that there is a cumulative breakdown of rRNAs, which results in a loss of ribosomes and protein synthetic capacity. After either of the test genes is maximally induced, there is a growing fraction of protein synthesis invested in beta-galactosidase or delta tufB that is matched by a comparable decrease of the fraction of normal protein synthesis. We have also observed enhanced accumulation of two heat shock proteins during overexpression. Finally, after several hours of overexpression of either test protein, the bacteria are no longer viable. These results are relevant to the practical problems of obtaining high expression levels for cloned proteins.

Mechanisms of Argon Retention in Clays Revealed by Laser 40Ar-39Ar Dating

A method for dating clays is important for studies of weathering, diagenesis, hydrocarbon migration, and the formation of major metalliferous deposits. However, many attempts have produced imprecise or inaccurate results. Data from shales show that, contrary to expectations, the (40)Ar-(39)Ar dating technique can be successfully used to determine the diagenetic age of ancient sediments because (39)Ar losses during irradiation are controlled by release from low retentivity sites in illite equivalent to those that have lost radiogenic (40)Ar in nature, rather than by direct recoil as is generally assumed.

[Pathologic characteristics of diffuse alveolar damage induced by paraquat in rat lungs]

Pathologic characteristics and events of paraquat (PQ) induced diffuse alveolar damage were observed by pathohistologic and ultrastructural studies of the lungs of rats, which were given a single intraperitoneal injection of PQ 25mg/kg body weight and sacrificed 6 hours to 45 days later. Results showed that the capillary endothelial and type I epthelial cells were mainly damaged, and associated with interstitial oedema, haemorrhage and hyaline membrane formation of the alveoli, and accentuated alveolitis. The lesions were located in the alveolar structural units and very diffuse in distribution. When the pulmonary damage became irreversible, it then led to fibrosis.

Role of oxygen derivatives in the cytotoxicity and DNA damage produced by asbestos on rat pleural mesothelial cells in vitro

The role of reactive oxygen metabolites in the toxic effects of asbestos on pleural mesothelial cells is not well defined. We exposed rat pleural mesothelial cells (RPMC) to chrysotile and crocidolite fibers (0-40 micrograms/cm2) in the presence or absence of catalase and superoxide dismutase (SOD). Cell injury was measured using the colorimetric 3-4 (5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and DNA damage was evaluated in terms of unscheduled DNA synthesis (UDS). Catalase (100 U/ml) and SOD (250 U/ml) protected RPMC against asbestos-induced cytotoxicity and DNA damage. However, the inactivated enzymes and bovine serum albumin also showed some protection, suggesting that the effect of antioxidant enzymes may be partly related to their protein nature. These results suggest that oxygen derivatives are partly involved in the toxic effects of asbestos on cultures of RPMC. The presence of extracellular proteins may also decrease asbestos-produced toxicity by reducing the degree of RPMC-fiber interaction.

Air samples from a building with asbestos-containing material: asbestos content and in vitro toxicity on rat pleural mesothelial cells

Buildings equipped with asbestos-containing material may release asbestos fibers, the toxicity of which remains uncertain because of the generally low dose level. In 22 air samples collected in a building the asbestos level ranged between 0 and 0.027 f/ml. Both chrysotile and amphiboles were found. There was no association between in vitro cytotoxicity on rat pleural mesothelial cells and asbestos content, but there was a significant correlation with the total amount of particulate material. Four samples exhibited an enhancement of DNA synthesis in cells arrested in G1 with 5 mM hydroxyurea. This is more likely related to the particulate matter associated with asbestos fibers.

Effects of U-50 488H, a kappa-agonist, on action potentials of isolated ventricular papillary muscle of guinea pigs

Trans(+-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]-benzeneacetamide-methanesulfonate-hydrate (U-50 488H), a specific kappa-agonist, at 1-10 mumol.L-1 caused concentration-dependent reductions in the action potential duration at 50% and 90% of repolarization (APD50 and APD90) without modifying the resting potential (RP), the action potential amplitude (APA) and the maximal upstroke velocity (Vmax). The effects were attenuated by (-)-(1R,5R,9R)-5,9-diethyl-2-(3-furylmethyl)-2L-hydroxy-6,7-benzomorphan (M(r) 2266 BS, 1 mumol.L-1), a specific kappa-antagonist which itself had no effect on the action potentials of the ventricular papillary muscle of guinea pigs, indicating that U-50 488H at 1-10 mumol.L-1 acts via specific cardiac kappa-receptors. At 100 mumol.L-1, U-50 488H not only shortened APD50 and APD90, but also reduced RP, APA, and Vmax, which were not attenuated by Mr 2266 BS (1 mumol.L-1) suggesting that the effects of U-50 488H at 100 mumol.L-1 were probably nonspecific.

Cardiac electric activity of 1-(2-[(6-methoxyl)-naphthylmethyl])-1-methyl-N-piperidinylacethyl-6,7- dimethoxyl-1,2,3,4-tetrahydroisoquinoline in SHR and WKY rats

1-(2-[(6-Methoxyl)-naphthylmethyl)])-1-methyl-N-piperidinylacethyl -6,7- dimethoxyl-1,2,3,4-tetrahydroisoquinoline (CPU-23), a substituted tetrahydroisoquinoline, reduced the voltages of P wave and J point, prolonged PR interval, and slowed sinus rhythm of ECG in spontaneously hypertensive rats (SHR) and age-matched normotensive WKY rats. The effects of CPU-23 on cardiac electric activity were stronger in SHR than in WKY rats (P < 0.05 or P < 0.01). The results suggest that CPU-23 have a calcium antagonistic activity on rat hearts and that calcium antagonists may exert a stronger inhibition of the cardiac electric activity in hypertensive rats than in normotensive rats.

Calcium antagonistic and antiarrhythmic actions of CPU-23, a substituted tetrahydroisoquinoline

1. The effects of CPU-23 (1-(1-[(6-methoxyl)-naphth-2-yl])-propyl-2-(1-piperidine)-acetyl-6 ,7- dimethyoxy-1,2,3,4-tetra-hydroisoquinoline) were studied on mechanical and electrical activities, and intracellular free calcium ([Ca2+]i) of isolated cardiac tissues in order to investigate its spectrum and mechanisms of action in the heart. Its antiarrhythmic and haemodynamic effects in pentobarbitone-anaesthetized rats subjected to coronary artery ligation were also evaluated. 2. CPU-23 at 10(-6)-10(-4) M markedly inhibited slow action potential characteristics in guinea-pig papillary muscles and pace-maker action potential of rabbit sinoatrial node. It affected fast action potential only at 10(-4) M. None of the effects of CPU-23 was reversed by washout for up to 2 h. 3. Like nifedipine and diltiazem, CPU-23 decreased the heart rate of the isolated perfused heart of the rat. However, in contrast to these two classical calcium antagonists which dose-dependently inhibited the force of contraction, CPU-23 inhibited and stimulated the force of contraction at 10(-7)-3 x 10(-6) M and 10(-5) M, respectively. 4. CPU-23 at 10(-6)-10(-5) M inhibited the KCl-induced [Ca2+]i increase in the Ca2+ medium, but did not affect the caffeine-induced [Ca2+]i increase in the Ca(2+)-free medium in isolated ventricular myocytes. 5. CPU-23 at 1-5 mg kg-1 reduced dose-dependently ventricular arrhythmias including ventricular ectopic beats, VT and VF as well as mortality during coronary artery ligation. At 2.5-5 mg kg-1 it even abolished VF, which was accompanied by 100% survival. 6. It is suggested that CPU-23 has calcium antagonistic properties in cardiac tissues. It selectively blocks the transmembrane influx of extracellular Ca2+ through Ca2+ channels, thus reducing the heart rate and developed tension, altering the slow action potential characteristics and producing antiarrhythmic effect against ischaemic arrhythmias.

Quantification and comparison of HIV-1 proviral load in peripheral blood mononuclear cells and isolated CD4+ T cells

HIV proviral load was determined by quantitative DNA polymerase chain reaction (PCR) in peripheral blood mononuclear cells (PBMC) and lymphocyte subsets isolated by cell sorter. Provirus measured in PBMC, when expressed as HIV copy number per million CD4+ cells, resulted in values which approximated those obtained from sorted CD4+ T lymphocytes. A cross sectional analysis of HIV proviral load in CD4+ T cells from 25 previously untreated and 30 zidovudine-treated seropositive patients with CD4+ T-cell counts between 25 and 802/mm3 demonstrated HIV copy numbers ranging from 1 copy per 10,000 cells in early disease to 1 copy per 10 cells in advanced disease. HIV proviral load can be rapidly assayed by PCR to give a reproducible value which varies over a 1,000-fold range and is positively correlated with cell infectivity as measured by a quantitative micrococulture assay. A less technically demanding assay using PBMC as substrate can give similar results to those obtained with sorted CD4+ T cells.

Cardiovascular effects of substituted tetrahydroisoquinolines in rats

1. A series of substituted tetrahydroisoquinolins derived from the cleavage products of tetrandrine were found to inhibit [3H]-nitrendipine binding to rat cerebral cortical membranes. Those compounds which displaced [3H]-nitrendipine binding were also able to inhibit high KCl-induced contraction of rat aorta in vitro. 2. There was a significant correlation between the ability of these tetrahydroisoquinolines to inhibit [3H]-nitrendipine binding and KCl-induced contraction (r = 0.99, P less than 0.001). 3. CPU-23 (1-(1-[(6-methoxy)-naphth-2-yl])-propyl-2-(1-piperidine)-acetyl- 6,7- dimethoxy-1,2,3,4-tetrahydroisoquinoline), one of the most potent compounds identified in this series, behaved as a simple competitive inhibitor at the [3H]-nitrendipine binding site and reduced the apparent affinity but not the maximal number of binding sites in saturation analysis. 4. In contrast to nifedipine which caused hypotension and tachycardia, CPU-23 induced both hypotension and bradycardia in a dose-dependent manner in pentobarbitone-anaesthetized Sprague-Dawley rats, spontaneously hypertensive and age-matched normotensive WKY rats. 5. It is suggested that CPU-23 may exert its cardiovascular effects via interaction with the dihydropyridine binding site on the L-type calcium channel.

[Textual study on traditional Chinese drugs caodoukou and baidoukou]

Through a critical study of herbalogy, it is concluded that the mature seeds of Alpinia zermubet were used as caodoukou in ancient times. The original plant of Yutao recorded in Zhiwu Mingshi Tukao may be the species of Alpinia katsumadai. Baidukou used in ancient times may be the seeds of Alpinia katsumadai found in the south of China, or Amomum compactum and Am. kravanh imported from foreign countries.

Use of mesothelial cell cultures to assess the carcinogenic potency of mineral or man made fibers

Natural mineral fibers may produce pulmonary cancers and mesothelioma. In contrast with lung cancer, the incidence of fiber-induced mesothelioma is not enhanced in smokers compared to non smokers. It is therefore of special interest to use mesothelial cells to study the toxicity of natural or man made mineral fibers. Several years ago, we have developed a method to culture rat pleural mesothelial cells (RPMC). We have first studied the effects of asbestos fibers by the application of in vitro tests formerly developed to determine the genotoxicity and transforming potency of soluble xenobiotics. Moreover, we have determined whether RPMC expressed cytochromes P450 known to metabolize polycyclic aromatic hydrocarbons. This paper reviews the results obtained so far. It has been found that asbestos fibers produced a cell transformation and a genotoxicity characterized by the formation of aneuploid cells, abnormal anaphases, chromosomal aberrations and DNA repair (UDS). In addition, RPMC expressed different forms of cytochromes P450. It is nowadays suggested that the tumorigenic potency of asbestos fibers may be related to the fiber dimensions, to their surface properties and in vivo biopersistence; this term involves the fiber solubility in biological medium and the fiber epuration from the lung by clearance mechanisms. Experiments are now in progress to determine whether the in vitro effects are dependent on the fiber parameters suggested as playing a role in the carcinogenic potency.

Coding assignments of the genome of adult diarrhea rotavirus

Adult diarrhea rotavirus (ADRV) has caused epidemics of diarrhea in China since 1982 and remains the only group B rotavirus associated with widespread disease in humans. We recently characterized the proteins of ADRV and have now proceeded to identify the gene segments encoding each protein. Viral RNA transcripts were synthesized in vitro with the endogenous viral RNA polymerase and separated by electrophoresis in agarose. The individual transcripts were translated in a cell-free system using nuclease-treated rabbit reticulocyte lysates. The translation products were compared with polypeptides found in purified virus and were characterized by SDS-PAGE, immunoprecipitation, and Western blot analysis using antisera to double- and single-shelled virions, virus cores, and monoclonal antibodies. Furthermore, individual RNA transcripts were hybridized to total dsRNA to determine their genomic origin. Based on this analysis, the core polypeptides VP1, VP2 and VP3 are encoded by segments 1, 2, and 3, respectively. The main polypeptides in the inner capsid, VP6, and the outer capsid, VP4 and VP7, are encoded by segments 6, 4, and 8 respectively. Segments 5, 7, and 9 code for 60, 45, and 30 kDa nonstructural polypeptides. Two other nonstructural polypeptides (24 and 25 kDa) are derived from gene segment 11. Gene segment 10 codes for a 26 kDa polypeptide that is precipitated with serum to ADRV and may be a structural protein VP9. With this exception, gene coding assignments of ADRV are comparable to those of the group A rotaviruses. Our results have clear implications for further work in cloning, sequencing, and expression genes of ADRV and can provide direction towards understanding the origin and the evolution of this virus.

Antagonistic effects of dihydropyridines and verapamil on CaCl2 and 5-HT-evoked contraction in porcine coronary artery

In porcine coronary arterial strips, the antagonistic effects of nifedipine (Nif), nimodipine (Nim), nicardipine (Nic), felodipine (Fel), and verapamil (Ver) to CaCl2-evoked contraction in Ca(2+)-free, K(+)-depolarized solution were greater than that to 5-HT. The order of potency (pD2') was Nif (9.1) greater than Fel (8.4) greater than Nim (7.9) greater than Nic (7.8) greater than Ver (7.2) to CaCl2 and Nif (8.3) greater than Nim (7.5) greater than Fel (6.8) greater than Ver (5.6) greater than Nic (5.3) to 5-HT. Ver inhibited 2 components of 5-HT-evoked contraction in Ca(2+)-free solution, but Fel inhibited only extracellular Ca(2+)-dependent contraction, suggesting that their action modes are different.

[Effect of nimodipine on the contraction and the Ca influx of rat aorta]

The relaxant effect of nimodipine (Nim) on rat aorta was studied in vitro. Nim inhibited KCl-induced contraction (IC50 = 40 nmol/L) more potently than NE-induced contraction (IC50 = 20 mumol/L), but did as equipotently as KCl-induced 45Ca influx (IC50 = 30 nmol/L). There was a positive correlation between inhibiting the KCl-induced 45Ca influx and the contraction (r = 0.98). However, it inhibited the NE-induced 45Ca influx (IC50 = 60 nmol/L) more potently than the NE-induced contraction. Verapamil inhibited the 2 components of NE-induced contraction significantly, while Nim only inhibited the contraction evoked by extracellular Ca2+ influx significantly. Nim did not influence the 45Ca influx into resting cells of rat aorta. These results suggest that the relaxant effect of Nim on rat aorta may be closely related to the blockade of Ca2+ entry through both potential-dependent calcium channels (PDC) and receptor-operated calcium channels (ROC), while the action on PDC seems to play a more important role than that on ROC.

Investigation of an outbreak of adult diarrhea rotavirus in China

In 1987 an epidemic of diarrhea associated with adult diarrhea rotavirus (ADRV) occurred in Qinhuangdao City, China, affecting more than 200 persons and causing 2 deaths. The outbreak was introduced by a person returning from an epidemic area and was spread initially to his family members and subsequently to the entire community. Adults were at greater risk of diarrhea than children 0-4 y of age and, the duration of illness increased significantly with increasing age. ADRV was identified by ELISA and electron microscopy. The electropherotypes of all positive specimens were identical, consistent with the single point-source introduction of the virus. Seroconversion was detected in 6 of 7 ill persons with a blocking ELISA. Both asymptomatic infection and person-to-person spread identified in this epidemic suggest that current emphasis on preventing waterborne transmission may not control the introduction of ADRV into new areas. The predisposition of adults for more severe disease with ADRV is similar to the pattern observed with other enteric viruses such as the Norwalk agent and hepatitis A.

Seroepidemiology of adult diarrhea rotavirus in China, 1977 to 1987

In 1982, large outbreaks of diarrhea that were caused by group B adult diarrhea rotavirus (ADRV) occurred throughout the People's Republic of China. Until 1982, group B rotavirus had never been associated with disease in humans. To determine whether ADRV was a new virus introduced in 1982 or had been present before that time, we examined antibody titers of ADRV in gamma globulin (pooled immunoglobulin) pools that were prepared during 1977 to 1987 in four cities in the People's Republic of China (Shanghai, Lanzhou, Wuhan, and Chandu). ADRV antibodies were assayed by using a blocking enzyme-linked immunosorbent assay. Antibodies were present in most Chinese gamma globulins tested, including those collected in Shanghai before the 1982 epidemic, and absent from American reference pools. The highest titers of antibody to ADRV (3,200) were found in gamma globulins collected in 1983 in Shanghai just after the epidemic, and these were fourfold higher than titers present in the preceding years. The quality of the gamma globulins stored for up to 12 years was tested by measuring levels of immunoglobulin G to group A rotavirus; these were equally high in gamma globulin pools prepared in the United States and in all samples from the People's Republic of China. Serum samples from patients from an outbreak of ADRV had elevated titers to ADRV 3 and 16 months after the onset of symptoms. These findings, as well as other epidemiologic findings on ADRV, suggest that the organism is an important and continuing cause of diarrhea in the People's Republic of China, was present before the first epidemic in 1982, and represents a risk to surrounding populations in Asia.

Purification and characterization of adult diarrhea rotavirus: identification of viral structural proteins

Adult diarrhea rotavirus (ADRV) is a newly identified strain of noncultivable human group B rotavirus that has been epidemic in the People's Republic of China since 1982. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western (immuno-) blot analysis to examine the viral proteins present in the outer and inner capsids of ADRV and compared these with the proteins of a group A rotavirus, SA11. EDTA treatment of double-shelled virions removed the outer capsid and resulted in the loss of three polypeptides of 64, 61, and 41, kilodaltons (kDa). Endo-beta-N-acetylglucosaminidase H digestion of double-shelled virions identified the 41-kDa polypeptide as a glycoprotein. CaCl2 treatment of single-shelled particles removed the inner capsid and resulted in the loss of one polypeptide with a molecular mass of 47 kDa. The remaining core particle had two major structural proteins of 136 and 113 kDa. All of the proteins visualized on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were antigenic by Western blot analysis when probed with convalescent-phase human and animal antisera. A 47-kDa polypeptide was most abundant and was strongly immunoreactive with human sera, animal sera raised against ADRV and against other group B animal rotaviruses (infectious diarrhea of infant rat virus, bovine and porcine group B rotavirus, and bovine enteric syncytial virus) and a monoclonal antibody prepared against infectious diarrhea of infant rat virus. This 47-kDa inner capsid polypeptide contains a common group B antigen and is similar to the VP6 of the group A rotaviruses. Human convalescent-phase sera also responded to a 41-kDa polypeptide of the outer capsid that seems similar to the VP7 of group A rotavirus. Other polypeptides have been given tentative designations on the basis of similarities to the control preparation of SA11, including a 136-kDa polypeptide designated VP1, a 113-kDa polypeptide designated VP2, 64- and 61-kDa polypeptides designated VP5 and VP5a, and several proteins in the 110- to 72-kDa range that may be VP3, VP4, or related proteins. The lack of cross-reactivity on Western blots between antisera to group A versus group B rotaviruses confirmed that these viruses are antigenically quite distinct.