[Experimental study on induction of lung cancer in hamster by fifteen chemical elements in the industrial dust from Yunnan Tin and other mines]

To exclude the carcinogenicity of trace radioactive elements in the mine powder and flue dust and clarify those inorganic chemical elements related to carcinogenesis of lung cancer, 15 non-radioactive inorganic chemical elements (CM1) responsible for mutagenesis, tumorigenesis and promotion of cancer from mine powder and flue dust were mixed for Ames test and carcinoma-inducing-experiment in animals. The results were as follows: 1. Ames test of CM1 showed positivity. 2. Lung cancer-inducing-experiment of CM1 in the hamster was successful with an incidence of 8.8% whereas in the control group, no lung cancer developed which showed that CM1 was related to the development of lung cancer. 3. Hyperplastic cells under light microscope showed Type II alveolar cells and Clara cells under electron microscope. It is possible that hyperplastic, precancerous and malignant cells in the lung are derived from these two kinds of cells. One case of multiple microcarcinoma was found in this experiment.

[Rapid identification of Mycobacterium tuberculosis and other mycobacteria with Mycobacterium tuberculosis whole chromosomal DNA probe]

The dot-blots containing DNA isolated from nonmycobacterial and mycobacterial microorganisms were hybridized with 32P-labeled M. tuberculosis whole chromosomal DNA at the various temperatures. The probe did not cross-hybridize to DNA of nonmycobacterial microorganisms (E. coli, Plasmid pUC19, Nocardia asteriodes), nor with DNA from all mycobacteria tested except M. bovis BCG under the higher temperature conditions. Microorganisms could also be directly spotted and lysed on nitrocellulose filters and used for hybridization thus making this technique suitable for clinical diagnosis.

Mortality of population in China and Japan: a comparative analysis

The author compares mortality in China and Japan from 1950 to 1985 and analyzes the differences between the two countries. Consideration is given to sex differences, regional differences, and trends in the major causes of death. The analysis shows "the gap between China and Japan in the health standards of the population [and also suggests] a course for [reducing] mortality of the Chinese population.... There is great potential...of reducing infant mortality, especially for female infants....Moreover, the further control of infectious diseases can still play a major role in raising the average life expectancy of the Chinese population in the years ahead."

Alteration by perfluorodecalin of hepatic metabolism and excretion of phenobarbital

The bile duct was cannulated in rats that had been infused intravenously with an emulsion of perfluorodecalin at intervals from 2 to 34 weeks earlier. After injection of [14C]phenobarbital, urine and bile were collected during the next 24 hr and were analyzed for phenobarbital and its metabolites. There was a decrease in the biliary excretion of phenobarbital and its metabolites for several weeks after infusion of perfluorodecalin, but conjugation of the metabolites was not decreased. The reduced excretion returned to normal after about 20 weeks.

Effects of intravenous emulsified perfluorochemicals on hepatic cytochrome P-450

Intravenous infusion of emulsified perfluorodecalin in rats caused a large increase in hepatic cytochrome P-450 concentration which persisted for many weeks. In contrast, hepatic cytochrome P-450 concentration was not changed significantly after infusion of perfluorotributylamine, but subsequent administration of phenobarbital caused the usual increase of cytochrome P-450. The cytochrome P-450 activity for demethylation of benzphetamine was decreased slightly after perfluorodecalin but was unchanged after perfluorotributylamine. The difference in the effects of these perfluorochemicals on hepatic cytochrome P-450 may be related to the difference in the time these compounds are retained in the liver.

Prolonged cardiac arrest and resuscitation in dogs: brain mitochondrial function with different artificial perfusion methods

Clinical techniques for artificial perfusion have not previously been examined directly for their effects on brain high-energy metabolism. Our study involved 24 large mongrel dogs that were anesthetized, instrumented for central venous intravenous access, and subjected to craniotomy to expose the dura and underlying parietal cortex. The animals were divided into the following six experimental groups of four animals each: nonischemic controls; 15-minute cardiac arrest without resuscitation; 45-minute cardiac arrest without resuscitation; 15-minute cardiac arrest plus 30 minutes resuscitation with conventional cardiopulmonary resuscitation (CPR); 15-minute cardiac arrest plus 30 minutes resuscitation with interposed abdominal compression (IAC) CPR; and 15-minute cardiac arrest plus 30 minutes resuscitation with internal cardiac massage. Cardiac arrest was induced by central venous injection of KCl 0.6 mEq/kg, and it was confirmed by continuous ECG monitoring. The three active resuscitation models included administration of NaHCO3 and epinephrine, but no attempt was made to restart the heart by defibrillation during resuscitation. At the indicated time in each group, a 4- to 5-g sample of brain was removed through the craniotomy, immediately cooled to 0 C and processed for isolation of mitochondria. The mitochondria were studied for their content of superoxide dismutase and for quantitative oxygen consumption with glutamate/malate substrate during resting and ADP-stimulated respiration. Our results show a significant drop in brain mitochondrial superoxide dismutase activity during the first 15 minutes of cardiac arrest. There is minimal injury to brain mitochondrial oxygen consumption during both 15 and 45 minutes of complete ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Projections from the cochlear nucleus to the cerebellum

The connections between the brainstem auditory system and the cerebellar auditory area in the posterior vermis (VI, VII, and VIIIA) were studied using the horseradish peroxidase technique. Injections also were made in the cerebellar hemispheres, the paramedian and the vestibulocerebellum (VIIIB, IX). Labeled cells were found in the cochlear nuclei bilaterally, but not in the superior olivary complex or the inferior colliculus. As the injection sites moved more laterally from the vermis area to the paramedian and the cerebellar hemispheres, the number of labeled cochlear nucleus neurons decreased progressively. This observation suggests that the terminals of the cochlear-nucleus-cerebellum projection tend to concentrate in the vermis auditory area. In the cochlear nucleus, labeled cells did not appear to belong to a single, homogenous cell type, nor did the cells group into a single area in the cochlear nucleus. The total number of labeled neurons in one cochlear nucleus did not exceed 200 in our largest injection.

The mechanism of ageing of phosphonylated acetylcholinesterase

1. The extent of potential reactivation of organophosphate-inhibited acetylcholinesterase decreases with time, a phenomenon called ageing. Ageing is due to dealkylation of the alkoxyl group of the residue bound to the enzyme. The rate of ageing is proportional to the electron-donating capacity of the alkyl group. 2. The ageing of phosphophonylated cholinesterase cal also be demonstrated using a phrenic nerve-diaphragm preparation. The same relationship between the rate of ageing and the structure of the alkyl group was observed. 3. Ageing occurs much faster in electrically stimulated preparations than in resting preparations. This may be due to production of a more acidic environment for the enzyme at the active centre by the products of hydrolysis of the acetylcholine released by stimulation.