[Mutagenicity of gastric juice in patients with chronic gastritis]

Mutagenicity of fasting gastric juice from 108 chronic gastritis patients in high- and low-risk areas of stomach cancer was assayed using in vitro SCE test in cultured human lymphocytes and micronucleus test in cultured Chinese hamster V79 cell. The results showed that mutagenicity could be found in this gastric juice. The positive rate of these two tests, SCE/cell, micronucleated cell rate and micronucleus rate were significantly higher in high-risk area than in low-risk area (P less than 0.01). There was a tendency that the mutagenic activity was higher in high pH than in low pH gastric juice and in males than in females. In high-risk area, the mutagenicity of gastric juice was obviously higher in younger than in elder aged group. Because no S9 was added in this test system, the results seem to suggest that the mutagenicity found in the gastric juice of patients with chronic gastritis might be, at least in part, related to direct-acting N-nitroso-compounds synthesized in the stomach.

Turnover of central biogenic amines in two-kidney, one-clip renal hypertensive rats

Turnover rates, as estimated from the accumulation of the intermediates dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) following decarboxylase inhibition, were used to investigate the relationship between central catecholaminergic and serotonergic neurons and the development of hypertension in 2-kidney, 1-clip renal hypertensive rats. Results indicated that at one week following clipping, DOPA accumulation was increased in the midbrain-pons. At 5 weeks no changes were observed. At 20 weeks a lower accumulation of both DOPA and 5-HTP was observed in the posterior hypothalamus while in the medulla oblongata DOPA accumulation was lower and in the midbrain-pons 5-HTP accumulation was reduced.

[Dengue vector density survey in Liuchiu, Pintung, Taiwan]

The first outbreak of dengue in Taiwan in 35 years was recorded in the summer of 1981 in Liuchiu, Pintung, a small offshore island of southern Taiwan. An investigation team visited the affected area during the period of 14-17 October 1981 and collected 8,641 mosquito larvae, of which 4,432 were Aedes aegypti and 4,182 were Ae. albopictus. The house index, container index and Breteau index were 44.2, 23.9 and 73.0 for Ae. aegypti and 41.3, 17.0 and 51.9 for Ae. albopictus, respectively. Both species of mosquitoes are peridomestic breeders, with larvae found in water-holding containers in or outside houses. Ae. albopictus is indigenous, but Ae. aegypti may be of recent introduction to the island. As the two species are closely related, the larvae of both species were found co-existent in only 2.3% of positive containers. This supports the hypothesis of the "competitive exclusion principle", i.e., competition is possibly occurring on this island.

Detection of antibodies to HTLV-III by ELISA in AIDS risk groups in Taiwan: a preliminary report

A total of 2321 serum samples were collected from a variety of AIDS risk groups. The samples were tested for anti-HTLV-III using ELISA. Low prevalences of seropositivity were detected in the high-risk groups. Among 120 homosexuals/bisexuals, one seropositive suffering from full-blown AIDS was an American traveler. Another native homosexual who yielded a high ELISA reading was a "possible" AIDS. Three hemophiliacs with strongly positive reactions received injections of a U.S.-produced factor VIII; all are asymptomatic currently. A patient with hairy cell leukemia had a markedly elevated ELISA reading. Another patient with syphilis also had a markedly high reading, despite having no other known risk factor. Among the low-risk groups a patient who had suffered from oral candidiasis for eight years had no risk factor, yet he yielded repeatedly high ELISA readings. Another patient with a weak positive reaction was a symptomless blood donor. This preliminary study concludes that Taiwan is several years behind the U.S. and is at present not an endemic area for AIDS. To achieve successful AIDS control in the future, however, the homosexuals in Taiwan should change their sexual behavior now. Since many initially weakly-reactive samples became negative on repeated testing it appears that non-specific or false positive ELISA reactions occur frequently. Accordingly when ELISA is used for diagnostic purposes, additional confirming tests are mandatory.

Disease-specific and tissue-specific production of unintegrated feline leukaemia virus variant DNA in feline AIDS

Feline leukaemia viruses (FeLVs) have long been known to be associated with induction of proliferative and anti-proliferative diseases of domestic cats. Strains of FeLV have been recognized which specifically induce lymphosarcoma, aplastic anaemia, myelodysplastic anaemia, and, recently, feline AIDS (acquired immune deficiency syndrome), a naturally occurring immunosuppressive syndrome strikingly similar to human AIDS which is lethal in 100% of inoculated and viraemic specific-pathogen-free (SPF) cats. Here, we have analysed FeLV DNA in tissues of 22 SPF cats that had been inoculated with the feline AIDS strain (FeLV-FAIDS) and we find two classes of viral DNA--a monotypic common form which is detectable in bone marrow regardless of disease state, and variant forms, recognizable by restriction site differences, whose appearance correlates with onset of disease symptoms and persists throughout the course of the disease. FeLV-FAIDS variant DNA is detected at high concentration (10-50 copies per cell) and principally as unintegrated viral DNA (UVD) in bone marrow of cats with feline AIDS. In marked contrast high levels of UVD were not present in cats in the terminal-stages of T-cell lymphosarcoma, aplastic anaemia, or myelodysplastic anaemia induced by other FeLV strains. These results parallel recent observations in humans, where high levels of UVD were sometimes found in cells derived from AIDS patients infected with human T-lymphotropic virus type III (HTLV-III)/lymph-adenopathy-associated virus (LAV), and suggest that persistence of unintegrated variant viral DNA is a crucial indicator of retrovirus-induced cytopathic disease syndromes such as AIDS.

[Effects of single and repeated oral administration of MK-421 and captopril on blood pressures in normotensive and experimental hypertensive rats]

In the single dose study, the aortic blood pressure in conscious normotensive rats, 2-kidney, 1-clip renal hypertensive rats (2K-RHR), 1-kidney, 1-clip renal hypertensive rats (1K-RHR) or DOCA hypertensive rats was measured for 24 hr after the oral administration of angiotensin converting enzyme (ACE) inhibitors such as MK-421 or captopril. MK-421 at 3 mg/kg and captopril at 10 mg/kg markedly lowered the blood pressure of 2K-RHR. MK-421 at 10 mg/kg and captopril at 30 mg/kg only modestly lowered the blood pressure of 1K-RHR. In contrast, both ACE inhibitors failed to reduce blood pressure in DOCA and normotensive rats. In the repeated dose study, the systolic blood pressures in normotensive rats, 2K-RHR or spontaneously hypertensive rats (SHR) were measured twice a week for 3 weeks treatment of either MK-421 at 3 mg/kg or captopril at 10 mg/kg. Both ACE inhibitors produced significant antihypertensive effects in these model rats, and the effects were sustained throughout the treatment period. The antihypertensive effects in 2K-RHR were greater than those in SHR and normotensive rats. These results indicate that MK-421 and captopril cause the most significant antihypertensive effect in 2K-RHR in which the renin-angiotensin system played a dominant role in blood pressure regulation. The antihypertensive effect of MK-421 was approximately 3 times as potent as that of captopril in these hypertensive models.

Effects of kanamycin on cochlear nuclear evoked responses and behavioral responses in C57BL/6J mice

The effect of kanamycin on auditory function was investigated in C57BL/6J mice. Results showed that kanamycin treatments (400 mg/kg/day, injected between 10 to 13 days of age) caused severe cochlear damage, particularly to the outer hair cells, and elevation of cochlear nucleus evoked-response thresholds. The treatment also rendered the treated animals susceptible to audiogenic seizures, suggesting a change in the animals' reactivity to intense sounds. However, unlike the effect of noise, exposure to kanamycin did not cause the treated animals to show abnormal augmentation of cochlear nucleus evoked-response amplitude when stimulated at high intensities.

The sensitive period for ototoxicity of kanamycin in mice: morphological evidence

The ototoxicity of kanamycin was investigated in mice treated with the drug either from 6 to 9, 10 to 13, or 15 to 18 days of age. The results showed extensive damage to the outer-hair-cell (OHC) receptors of the cochlea in the 10-13-day group; some less severe damage to the OHC was found in the 6-9-day group, and little damage was observed in the 15-18 day group. The present finding is consistent with the view that the mouse cochlea is most vulnerable to the ototoxic effect of kanamycin during the period of its rapid development, i.e., between 10 and 13 days of age.

Adaptations of lactate metabolism in iron-deficient rats

Effects of dietary iron deficiency on lactate metabolism were studied in weanling female rats. Following an iron-deficient diet for 5 weeks, mean hemoglobin concentration was lowered to 6.4 g/dl relative to 12.2 in the control group. Mean plasma iron levels were 58 and 162 micrograms/dl, respectively. Significantly elevated resting lactate levels were observed in whole blood and plasma from iron-deficient anemic (relative to control) rats. Total activity of lactate dehydrogenase (LDH) was elevated in soleus and gastrocnemius muscles in response to iron deficiency from 269 +/- 51 to 364 +/- 60 (Mean +/- SD) and from 265 +/- 65 to 372 +/- 61 IU . 10(-3) . g-1, respectively. The LDH activity in heart was lowered from 700 +/- 61 to 593 +/- 45 IU . 10(-3) . g-1. The M3H and M2H2 isozymes in soleus were increased from 12.7 +/- 2.8 to 20.4 +/- 5.8% and from 19.4 +/- 6.1 to 28.2 +/- 3.6%, respectively. Similar increase was observed in M2H2 and MH3 in gastrocnemius from 9.8 +/- 0.9 to 14.8 +/- 2.0% and from 17.4 +/- 2.0 to 20.5 +/- 2.3%, respectively. The H4 isozyme was significantly reduced in soleus, gastrocnemius, and plantaris muscles from 27.7 +/- 4.7 to 12.4 +/- 4.4, from 15.8 +/- 1.9 to 7.2 +/- 2.9, and from 10.5 +/- 2.9 to 3.9 +/- 2.1%, respectively. It was suggested that iron-deficiency anemia induces an elevation of lactate production following an increase in total LDH activity and change in LDH isozyme patterns.

Mitochondrial NADH dehydrogenase in iron-deficient and iron-repleted rat muscle: an EPR and work performance study

Iron may affect both respiratory O2 transport and mitochondrial electron transport in the performance of muscle work. This study was designed to elucidate the molecular defect of iron-deficient work performance by identifying heretofore unmeasurable mitochondrial enzymes that are diminished by iron deficiency and may be restored by iron repletion. Female rats were made iron-deficient by dietary control and were repleted by oral iron. Iron deficiency reduced physical work capacity (treadmill running time), haemoglobin (Hb), and mitochondrial iron-sulphur (Fe-S) centres in heart and skeletal muscles; mitochondrial number was unaffected. Oral iron supplementation restored work capacity and Hb within 4 d to normal or near-normal levels, but in general Fe-S centres of mitochondria due to NADH dehydrogenase remained at iron-deficient levels. Subnormal concentrations of mitochondrial iron-dependent NADH dehydrogenase in muscle are not by themselves rate-limiting in work performance.

Selenium-containing tRNAs from Clostridium sticklandii. Cochromatography of seleno-tRNA I with L-VALYL-tRNA

It has been previously shown that Clostridium sticklandii specifically synthesized three readily separable 75Se-labeled tRNAs, designated seleno-tRNAs I, II and III, and the partially purified seleno-tRNA II cochromatographed with L-prolyl-tRNA on DEAE-Sephadex A-50 (Chen, C.S. and Stadtman, T.C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1403-1407). In the present study a highly purified 75Se-labeled tRNA I was obtained by chromatography on benzoylated DEAE-cellulose, DEAE-Sephadex A-50 and Sepharose 4B. The 75Se-labeled tRNA I cochromatographed with an L-valine-accepting species on DEAE-Sephadex A-50 and Sepharose 4B. Addition of a 285-fold molar excess of unlabeled L-valine to the L-valine acceptor activity assay mixture markedly decreased the amount of L-[14C]valine bound to seleno-tRNA I.

Sensitive periods of susceptibility to auditory trauma in mammals

Evidence is presented to support the hypothesis that the cochleae of young animals are more susceptible to auditory trauma than the cochleae of the adult. A sensitive period of heightened susceptibility to acoustic trauma from noise exposure has been demonstrated in three mammalian species. The cochlear pathology associated with this trauma is severe damage to the outer hair cell system. Abnormal growth of auditory evoked responses recorded in central auditory nuclei accompanies the receptor damage during the sensitive period. There is evidence of a similar sensitive period of susceptibility to cochlear insult from ototoxic drugs. The time frame of the sensitive period may be different for drug or noise insult to the cochlea, but the principal pathology of outer hair cell loss remains the same in both cases. The implication of these sensitive periods to auditory trauma, for human development is considered.

The sensitive period for induction of susceptibility to audiogenic seizures by kanamycin in mice

It has been found that administration of kanamycin (400 mg/kg daily) for 5 days was highly effective in inducing susceptibility to audiogenic seizures in BALB/c mice, if the drug was administered between the age of 10-14 postnatal days. The same drug dosage administered between the age of 5-19, 15-19, or 20-24 postnatal days was found to be ineffective. Since induction of seizure susceptibility is highly correlated with the degree of cochlear damage produced by either ototoxic drugs or noise, it was suggested that the age of 10-14 postnatal days could be the most sensitive period for the ototoxic effect of kanamycin.

Monte Carlo simulation studies of detectors used in the measurement of diagnostic x-ray spectra

Accurate determination of diagnostic x-ray spectra requires, among many other technical considerations, correction of the experimental data for the energy-dependent response of the x-ray detector. In this study, we investigated the energy response of three types of detectors (intrinsic germanium, lithium-drifted silicon, and sodium iodide) commonly used in the diagnostic energy range. We used a Monte Carlo simulation technique to compute photopeak efficiencies, escape peak losses, and Compton fractions as a function of incident x-ray energy for a variety of detector thicknesses and diameters. Calculated responses were compared with experimental results obtained for the Ge and Si(Li) detectors. The measurements, in which we used fluorescent x ray to simulate the monoenergetic beams assumed for the calculations, indicate good agreement between theoretical and experimental approaches. Techniques for correction of measured spectra for the known response of the detector were also evaluated.

Rapid development of acoustic trauma-induced audiogenic seizure risk in 3 strains of seizure-resistant mice

Audiogenic seizure risk can be induced in genetically seizure resistant mice by exposure to an intense noise a few days prior to testing for seizure. This experiment demonstrates that the priming induced seizure risk can develop within 6-16 h after priming. It was argued that this finding suggested an alternative hypothesis of priming involving peripheral auditory mechanisms.

Potentiation of acoustic-trauma-induced audiogenic seizure susceptibility by salicylates in mice

Combined exposure to noise and salicylates was found to produce greater acoustic trauma induced audiogenic seizure risk than exposure to the noise alone. The result suggests that salicylates could make the mouse cochlea more vulnerable to the traumatic action of noise.

Selenium-containing tRNAs from Clostridium sticklandii: cochromatography of one species with L-prolyl-tRNA

75Se-Labeled tRNAs were synthesized by Clostridium sticklandii cultures supplemented with 1 microM sodium [75Se]selenite or [75Se]selenocysteine. This process is highly specific for selenium; it occurred in the presence of 1.2 mM sodium sulfide and was not decreased by the further addition of a 500-fold molar excess of cysteine. The 75Se in these tRNAs was located in the polynucleotide portion of the molecules and not in esterified (alkali-labile) selenocysteine. Inhibition of cell multiplication by antibiotics that block either protein synthesis or DNA-dependent RNA synthesis did not prevent this 75Se incorporation. Three [75Se]tRNAs were separated from C. sticklandii cells labeled in the presence of chloramphenicol and were partially purified by chromatography on benzoylated DEAE-cellulose and DEAE-Sephadex A-50 columns. These were designated seleno-tRNAs I, II, and III according to their elution sequence from benzoylated DEAE-cellulose. Cochromatography of purified seleno-tRNA II on DEAE-Sephadex A-50 with an L-proline-accepting species suggests that it is a selenium-containing L-prolyl-tRNA.

Potentiation of noise-induced audiogenic seizure risk by salicylate in mice as a function of salicylate-noise exposure interval

Audiogenic seizure risk can be induced in genetically seizure-resistant BALB/c mice by exposure to an intense noise. Results of this experiment showed that combined exposure to noise and sodium salicylate could produce a greater priming effect than exposure to the noise alone, and the greatest potentiation effect was obtained when animals were exposed to the noise 6 hr after the intake of salicylate. The findings were taken as indirect evidence suggesting that the ototoxic action of sodium salicylate could potentiate vulnerability of the mouse cochlea to noise damage.

Acquisition of behavioral tolerance to ethanol as a function of reinforced practice in rats

The roles of both reward and the amount of reinforced practice on the development of behavioral tolerance to ethanol were studied in 32 hooded rats in a Skinner-box situation. The effects of ethanol were evaluated on two aspects of the bar-press response (FR15): latency to complete 15 bar presses and proficiency to earn rewards. Results showed that the behavioral tolerance, as indicated by diminishing effects of ethanol on performances over repeated exposures, developed rapidly. The extent of the developed tolerance was greater and more stable in animals which had reinforced practice while under the influence of ethanol than in animals which had non-reinforced practice. Animals which were exposed to the same amount of ethanol but practiced the response in a non-drug state showed little sign of tolerance to ethanol. These findings give further support to a previous view that learning processes may be involved in acquisition of behavioral tolerance to ethanol.

Conformation of L-cystathionine, a carba analog of cystine, and stereochemistry of hormone-receptor interactions

The conformation of L-cystathionine, a carba analog of L-cystine, has been studied in the solid state using X-ray diffraction techniques. Crystal of L-cystathionine are tetragonal, space group P41 with cell constants a = 6.691(1) A, c = 21.998(3) A and Z = 4. From diffractometer data to the limit of 2theta = 162 degrees for Cukalpha, the structure was refined using full-matrix least-squares to an R value of 0.061. L-Cystathionine is isostructural chemically to L-cystine and its crystal structure is isomorphous to tetragonal L-cystine (Chaney, M.O. and Steinrauf, L.K. (1974) Acta Crystallogr. 1330, 711--716). The crystal structure of L-cystathionine is disordered, leading to two slightly differing conformers of L-cystathionine (each with half occupancy) with same helical sense but running in opposite directions and occupying the locations of L-cystine molecules in tetragonal L-cystine structure. Their conformational similarity, even when no sterical constraints such as cyclization are present, offers an explanation of the activities of the carba analogs of neuro-hypophysial hormones in terms of the structural integrity of the disulfide-like bridges.

Translational specificity of Bacillus stearothermophilus ribosomes

The translational specificity of Bacillus stearothermophilus ribosomes was studied by determining the effectiveness of various synthetic RNAs as templates at 37 degrees and at higher temperatures. The effectiveness of poly(G,U) was maximal at a G:U ratio of 1:3; it declined with lower G content because of reduced ribosomal affinity for the RNA and, with higher G, because of interference by secondary structure. The effectiveness of poly(A,C,G,U) also declined when secondary structure was increased by increasing (G+C) content. Escherichia coli ribosomes exhibited a similar specificity for poly-(G,U), but had a lower sensitivity to interference by RNA secondary structure. In both bacterial species, sensitivity to secondary structure was determined by the 30S ribosomal subunit.

Specific configurations of hydrogen bonding. I. Hydrogen bonding and conformational preferences of N-acylamino-acids, peptides and derivatives

From a reexamination of the X-ray studies of the crystal structures of 27 N-acylamino acids, peptides and their derivatives and 30 linear peptides, it is concluded that specific formation of short intermolecular hydrogen bonds (2,5 to 2.6 A) from the carboxyl OH to the N-acyl oxygen is an important feature for N-acylamino acids. For N-acyl-N-amides, the formation of hydrogen bonds 2.7 to 2.9A long between N(acyl-H...O(amide) is strongly preferred. The dihedral angle delta between the N-acyl and carboxyl groups or adjacent amide groups shows a preference for values near 20 degrees or 90 degrees for N-acylamino acids and 90 degrees for N-acyl-N-amides.

[Comparative studies of antihypertensive effects of several beta-blocking agents in conscious rats (author's transl)]

The present study was undertaken to compare the antihypertensive effects of beta-blocking agents and to clarify the relations between antihypertensive effects and beta-blocking actions. In this study, blood pressure was measured by a direct cannulation of the abdominal aorta. Subcutaneous administration of carteolol and pindolol caused a significant fall in mean blood pressure in both normotensive and spontaneously hypertensive rats, whereas propranolol produced a rise in blood pressure. Maximum fall in blood pressure was observed 3 approximately 7 hr after the administration of carteolol and pindolol. In order to determine the beta-blocking action, changes in heart rate and blood pressure in response to isoproterenol (3 microgram/kg i.v.) were observed during the experiment. beta-Blocking action was found as early as 1 hr after subcutaneous administration. Carteolol showed the most effective blocking action throughout the experiment. Although beta-blocking agents lowered the blood pressure in this experiment, there was no apparent parallel between antihypertensive effects and beta-blocking action on the cardiac function.

Offset-induced audiogenic seizures

A relatively stereotyped seizure reaction can be triggered by the "offset" of an intense bell sound in C57BL/6J mice. Susceptibility to this offset-induced audiogenic seizure was found to depend upon the age of the animals tested (higher in older mice) and the duration of the noise exposure (more effective with longer exposure).

Analysis of hypotensive mechanisms of pindolol, a beta-adrenoceptor blocking drugs in rats

The hypotensive mechanisms of pindolol in anesthetized and conscious rats were investigated. Pindolol caused a fall in blood pressure in anesthetized, conscious and spinal rats, though in conscious rats a higher dose of the drug was required to produce such a response. This hypotension with pindolol in anesthetized and conscious rats was markedly inhibited by pretreatment with the drug itself or other beta-adrenoceptor blocking drugs. A similar phenomenon also occurred when isoproterenol was injected intravenously in anesthetized and conscious rats. The relationship between the hypotensive actions of four beta-adrenoceptor blocking drugs in anesthetized rats and their intrinsic beta-sympathomimetic actions in isolated catecholamine-depleted tracheal preparations was determined. Order of hypotensive potencies was the same as that of their intrinsic beta-sympathomimetic action, namely, pindolol greater than carteolol greater than bufetolol in equilibrium propranolol (p less than 0.05). These results suggest that the hypotension with pindolol is mediated through a decrease in the peripheral vascular resistance due to an intrinsic beta-sympathomimetic action of the drug.

Effect of clonidine on blood pressure, heart rate and body temperature in conscious rats

Effects of clonidine on blood pressure, heart rate and rectal temperature in conscious rats were examined. Clonidine (0.1-1 mg/kg s.c.) caused a prevailing pressor response and dose-dependently a fall in heart rate and body temperature. The pressor response to clonidine (0.3 mg/kg s.c.) was completely reduced by phentolamine (10 mg/kg s.c.), chlorpromazine (10 mg/kg s.c.) but not by hexamethonium (30 mg/kg i.p.), guanethidine (30 mg/kg s.c.) or reserpine (5 mg/kg s.c. 18 hr + mg/kg i.p. 4 hr prior to clonidine). Conversely, a remarkable potentiation of the pressor response to clonidine was observed after treatment with reserpine. The bradycardia with clonidine (0.3 mg/kg s.c.) was significanlty reduced by phentolamine, chlorpromazine or atropine (5 mg/kg s.c.) but was potentiated by reserpine. The hypothermia with clonidine (0.3 mg/kg s.c.) was not influenced by phentolamine or atropine but was significanlty potentiated by chlorpromazine. From the above results it is suggested that the prevailing pressor response to clonidine in conscious rats is due to a stimulation of peripheral alpha-adrenoceptors, the bradycardia with clonidine is exerted through the sympathetic pathway and the baroceptor-vagal reflex, and that the hypothermia with clonidine is mainly due to the central mechanism.

Effect of morphine and naloxone on priming-induced audiogenic seizures in BALB/c mice

1 Morphine (1-200 mg/kg s.c.) reduced the incidence and prolonged the latency of priming-induced audiogenic siezures in a dose-dependent manner. 2 This effect was reversed by naloxone (1 and 2 mg/kg) although naloxone was itself inactive. 3 This priming-induces seizure model may be useful in the study of tolerance and physical dependence.