Human antirabies treatment in the United States, 1972.

Data were examined on 965 persons treated in six States (Delaware, Florida, Georgia, Illinois, North Dakota, and South Carolina) and New York City in 1972 for possible rabies exposure. Males 10-19 years were found to be the group at greatest risk, and exposures occurred most frequently during the warm months. Dogs, other domestic animals, and wildlife were about equally responsible for human exposures in the six States, but 99% of the exposures in New York City involved dogs. Antirabies postexposure prophylaxis varied markedly among reporting areas and frequently did not follow current recommendations. The mean delay in initiation of treatment after exposure was 4 1/2 days. The mean number of doses of vaccine for treatment was 12; only 10% of the persons treated received antirabies serum.     

Liver microsomal uptake of (14C)vinyl chloride and transformation to protein alkylating metabolites in vitro.

[1,2-¹⁴C]Vinyl chloride gas was incubated with rat liver microsomes in an all-glass vacuum system. Microsomal uptake and irreversible protein binding of vinyl chloride radioactivity was determined. Both uptake of vinyl chloride by microsomes and alkylation of proteins by vinyl chloride metabolites were dependent on incubation time, enzymatically active microsomes, NADPH, oxygen, and the partial pressure of vinyl chloride in the atmosphere, and could be inhibited by carbon monoxide. During incubation in presence of NADPH, 10 times more vinyl chloride was taken up by microsomes than in absence of NADPH. Uptake of vinyl chloride by albumin solutions and liposomal suspensions was in a similar range compared to the microsomal uptake without NADPH. Addition of glutathione and cytoplasmic fractions to microsomal incubations with NADPH led to an increase in microsomal uptake of vinyl chloride and to a decrease in protein alkylation by vinyl chloride metabolites. If trichloropropene oxide was present in the microsomal incubation, the protein alkylation reaction by vinyl chloride metabolites was increased twofold, while the microsomal uptake of vinyl chloride was not influenced. Our results are consistent with the view that the microsomal uptake of vinyl chloride radioactivity is due to transformation of vinyl chloride gas to nonvolatile metabolites by microsomal enzymes and that chloroethylene oxide might be the primary microsomal metabolite of vinyl chloride capable of reacting with proteins.     

Positive correlation between decreased cellular uptake,NADPH-glutathione reductase activity and adriamycin resistance in Ehrlich ascites tumor lines

From a wild type strain of Ehrlich ascites tumor (EAT_WT) sublines resistant to daunorubicin (EAT_DNM), etoposide (EAT_ETO), and cisplatinum (EAT_CIS) have been developed in vivo. Increase in survival and cure rate caused by adriamycin (doxorubicin) have been determined in female NMRI mice which were inoculated i. p. with EAT cells. Adriamycin concentrations causing 50% inhibition of ^3H-thymidine (ICT) and ^3H-uridine incorporation (ICU) and intracellular adriamycin steady-state concentrations (SSC) were measured in vitro. Adriamycin resistance increased and SSC decreased in the following sequence: EAT_WT — EAT_CIS — EAT_DNM — EAT_ETO. When ICT and ICU were corrected for intracellular adriamycin concentrations in consideration of the different SSC (ICT_C, ICU_C), ICT_C and ICU_C still varied up to the 3.2 fold in EAT_CIS, EAT_DAM and EAT_ETO in comparison to EAT_WT. Thus, in addition to different SSC other factors must be responsible for adriamycin resistance. Therefore, enzymes which may play a role in the cytotoxicity related to adriamycin metabolism (NADPH-cytochrome P-450 reductase, NADPH-glutathione reductase, NADP-glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase) were measured. In contrast to the other parameters determined, NADPH-glutathione reductase was significantly (p<0.01) increased up to the 3.2 fold parallel to adriamycin resistance as determined by increase in life span, cure rate, ICT_C, and ICU_C, respectively. It is concluded that high activities of NADPH-glutathione reductase may contribute to an increase in adriamycin resistance of malignant tumors.Dedicated to Professor Dr. med. Herbert Remmer on the occasion of his 65th birthdaySupported by Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg, FRG: Sonderforschungsbereich 102, and Landesamt für Forschung Nordrhein-Westfalen, Düsseldorf, FRG     

Lipid peroxidation and cell damage in isolated hepatocytes due to bromotrichloromethane

Small amounts of malondialdehyde (MDA, about 0.5 nmol/10⁶ cells) were produced during 120-min incubation of isolated rat hepatocytes indicating lipid peroxidation in the cells. Trypan blue uptake and lactate dehydrogenase release followed MDA formation. MDA increased to about 3.5 nmol/10⁶ cells in the presence of 2 mm bromotrichloromethane (CBrCl₃). A parallelism of MDA production with trypan blue uptake and lactate dehydrogenase release was observed. The MDA production depended on the CBrCl₃ concentration in the incubation medium. A higher oxygen consumption of cells incubated in the presence of CBrCl₃ was detectable compared to controls. During incubation no increase in glutamate dehydrogenase release could be observed, even if 2 mm CBrCl₃ was present. This led us to conclude that lipid peroxidation induced by CBrCl₃ destroys the plasma membrane of the hepatocytes without seriously damaging mitochondria.     

Disposition of [1,2-14C] vinyl chloride in the rat

Rats were exposed to [1,2-¹⁴C] vinyl chloride in a closed system at initial concentrations below 100 ppm. When the system was occupied by 3 rats, a half-life of vinyl chloride in the system's atmosphere of 1.13 ± 0.12 h was observed. The volume of the system was 10.3 l. Calculation of the clearance of vinyl chloride from the system revealed that about 40% of inspired vinyl chloride is absorbed by lung. Therefore, changes in respiration did not influence uptake of vinyl chloride.Uptake of vinyl chloride by the rats was completely blocked by acute pretreatment with potent inhibitors of cytochrome-P-450-dependent microsomal drug metabolism (i.e., by 35 mg/kg 3-bromophenyl-4(5)-imidazole or 50 mg/kg 6-nitro-1,2,3-benzothiadiazole in 0.6 ml/kg DMSO). A weaker inhibition was observed after dosing SKF 525 A or 5,6-dimethyl-1,2,3-benzothiadiazole (50 mg/kg in 0.6 ml/kg DMSO). Metyrapone did not cause inhibition.Uptake of vinyl chloride was increased by pretreatment with DDT and, to a lesser extent, with clotrimazol. No significant stimulation of uptake was observed after pretreatment with phenobarbital, 3-methylcholanthrene, rifampicin, or chronic ethanol treatment.Immediately after exposure, highest radioactivity levels were observed in liver and kidney. The radioactive metabolites of ¹⁴C-vinyl chloride were rapidly excreted, largely by the kidneys. Excretion of radioactivity in the urine was 69.4 ± 2.6% within 24 h.     

Metabolism of 14 C-vinyl chloride in vitro and in vivo.

Rat liver microsomes metabolise 14 C-vinyl chloride to intermediates which irreversibly bind to the microsomal protein and to soluble proteins and RNA, when these compounds are added to the incubation. A superoxide (O2) generating system comprised of phenazine methosulfate and NADH also converts 14 C-vinyl chloride to metabolites which irreversibly bind to albumin. These data are consistent with the assumption of chloroethylene oxide being the primary reactive metabolite of vinyl chloride. If rats are exposed to 14 C-vinyl chloride, about half of the radioactive metabolites in the liver microsomal fraction is bound irreversibly to microsomal protein, when assessed immediately after exposure. Large amounts of polar, extractable, metabolites are present in the cytosol fraction. The amount of radioactivity in tissues of the rats, irreversibly bound immediately after exposure, comprises 10 - 40% of the total radioactivity in tissues. This percentage rises up to 70% after 48 hrs. Som radioactivity derived from 14 C-vinyl chloride is also incorporated into DNA and RNA of liver. Whereas the peak of incorporation of 14 C into DNA is already reached immediately after exposure to 14 C-vinyl chloride, specific labelling of RNA increases after exposure until its maximum after 24 hours.     

CCl4-induced lipid peroxidation in isolated rat hepatocytes with different oxygen concentrations

It has been difficult to demonstrate convincingly the occurrence of lipid peroxidation by increases in the concentration of thiobarbituric acid (TBA) reactants in response to carbon tetrachloride (CCl₄) in hepatocytes isolated from fed, nontreated rats. This study was undertaken to determine whether or not the incubation atmosphere and the content of the incubation media could be contributing factors for the inhibition of CCl₄-induced lipid peroxidation. Isolated hepatocytes incubated in either Eagle's minimum essential medium (EMEM) or Tris buffer were incubated with and without CCl₄ (1 or 5 μl/4 ml hepatocyte suspension) under an atmosphere of either air or carbogen (95% O₂:5% CO₂). Samples were taken at 30, 60, or 120 min for determination of ethane (in the gas phase), TBA reactants concentration, and leakage of lactate dehydrogenase (LDH). Under air, CCl₄ stimulated ethane formation and increased the concentration of TBA reactants in hepatocytes isolated from fed, nontreated rats. This stimulatory effect was found irrespective of the incubation medium, although absolute values were generally lower in Tris buffer than in EMEM. Losses of LDH were also observed with the higher concentration of CCl₄. When carbogen was the atmosphere for incubation, no significant increases in the lipid peroxidation parameters could be found in response to CCl₄. Again, this response was irrespective of the incubation medium. Under carbogen, CCl₄-induced LDH leakage was no longer observed. Thus, these data provide a possible explanation as to why it has been difficult to observe lipid peroxidation, as evidenced by elevated TBA reactants concentration in hepatocytes isolated from fed, nontreated rats.     

Alkane formation during liver microsomal lipid peroxidation

During treatment of animals with the hepatotoxin carbon tetrachloride (CCl₄) short-chain alkanes, e.g. ethane and n-pentane, are formed (1–6). It is now generally accepted that these alkanes originate from the decomposition of lipid hydroperoxides (7). However, studies with model compounds demonstrated that metal ions, e.g. iron, are involved in the breakdown of lipid hydroperoxides to alkanes (8, 9). Because we were interested whether metal ions are also involved in CCl₄-induced lipid peroxidation we studied the effect of ferrous ions on CCl₄-induced alkane formation in rat liver microsomes. This could be important, because lipid peroxides are fairly stable in absence of metal ions (10). First of all we had to develop an in vitro system which gives reproducible measurements of alkanes during microsomal incubation. Furthermore, we had to examine whether these alkanes are indeed formed in hepatic microsomes due to CCl₄. On the other hand, we had to find out what the optimal iron concentration in this system would be.     

Postabortal endometritis and isolation of Chlamydia trachomatis

A prospective study of 505 unselected women presenting for induced abortion was undertaken to determine the prevalence of Chlamydia trachomatis and to determine if cervical isolation of C trachomatis before abortion increases the risk of postabortal endometritis. A comparison of direct fluorescent antibody (slide) test with tissue culture for diagnosing C trachomatis infection also was evaluated in this population. C trachomatis was identified by culture in 89 patients (17.6%) and by direct slide test in 85 patients (16.8%). Six of 17 patients with postabortal endometritis were culture positive for C trachomatis, with a significant correlation between C trachomatis infection and development of endometritis observed (P less than .05). These data suggest C trachomatis may play an important role in postabortal endometritis.