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.