1. The O-dealkylation of seven 7-alkoxyquinoline derivatives by human hepatic and placental microsomes and the effect of maternal cigarette smoking on placental 7-alkoxyquinoline metabolism was studied. 2. None of several monoclonal antibodies to isoenzymes of cytochrome P450 had a clear effect on metabolism of the compounds by liver microsomes. 3. Maternal cigarette smoking induced the O-dealkylation of all of the 7-alkoxyquinoline derivatives, being greatest for 7-butoxy- and 7-benzyloxyquinoline. 4. Placental 7-alkoxyquinoline metabolism induced by smoking was partially inhibited by the monoclonal antibody 1-7-1 raised against 3-methylcholanthrene-induced rat liver P450. 5. None of the 7-alkoxyquinoline O-dealkylations could be assigned specifically to any known P450 isoenzyme in human liver or placenta.
The cytoplasmic calcium concentration ([Ca2+]i) was measured from Purkinje neurons in acutely prepared cerebellar slices. Neurons were loaded with calcium indicator Fura-2 by 40-min slice incubation in Tyrode solution containing 5 microM Fura-2/AM and 0.02% pluronic-F127. Bath applications of ATP (100 microM), epinephrine (10 microM) and histamine (100 microM) triggered a transient increase of [Ca2+]i in Purkinje neurons. ATP-induced [Ca2+]i elevation in Purkinje neurons was mimicked by ADP, but not AMP or adenosine pointing to the involvement of P2Y metabotropic purinoreceptors. Epinephrine-triggered [Ca2+]i responses were blocked by the selective alpha 1-antagonist prazosin and were mimicked by the alpha 1-adrenoreceptor agonist phenylephrine, and were not affected by beta- and alpha 2-adrenoreceptor agonists (isoproterenol and clonidine) and antagonists (propranolol and yohimbine). Histamine-induced [Ca2+]i responses demonstrated specific sensitivity to selective H1 antagonist chlorpheniramine, and were not sensitive to H2 and H3 histamine receptors modulators. The [Ca2+]i responses to all three agonists persisted in Ca(2+)-free extracellular media and were blocked by slice preincubation with thapsigargin (500 nM). We conclude that cerebellar Purkinje neurons are endowed with metabotropic P2 gamma purinoreceptors, alpha 1-adrenoreceptors and H1 histamine receptors which mediate the generation of intracellular [Ca2+]i signals via activation of Ca2+ release from inositol-1,4,5-trisphosphate-sensitive intracellular stores.
Purified murine tubular basement membrane (TBM) antigen (molecular weight, 32,000) induced interstitial lesions in Brown Norway (BN) rats. TBM antigen prepared from mice of 3 inbred strains--BALB/c, C3H/He, and C57BL/6--and outbred ddY mice possessed both antigenicity and nephritogenecity. Using these TBM antigens, the roles of humoral and cellular immunity in the development of interstitial nephritis (IN) and the genetic control of the induction of IN in inbred mice were investigated. BALB/c mice were highly susceptible to IN and showed a high antibody response and a high lymphocyte proliferative response to syngeneic and allogeneic TBM antigen, whereas C57BL/6 mice did not. C3H/He mice, in which minimal interstitial lesions developed, showed a high antibody response but a low proliferative response of T cells to TBM antigen. TBM antigen sensitized T cells induced interstitial lesions, but anti-TBM antisera did not do so. Thus, the development of IN seemed to be related closely to cellular immunity. Further studies with their hybrids, backcrosses, congenic mice, and recombinant mice suggested that the induction of IN and the immune response to TBM antigen are controlled by 1 or a few dominant genes, whose loci are within, or closely linked to, the H-2 complex.
A diverse array of bacterial species, including several potential human pathogens, was isolated from edible crabs collected in cold waters. Crabs collected near Kodiak Island, Alaska, contained higher levels of bacteria than crabs collected away from regions of human habitation. The bacteria associated with the crabs collected near Kodiak included Yersinia enterocolitica, Klebsiella pneumoniae, and coagulase-negative Staphylococcus species; the pathogenicity of these isolates was demonstrated in mice. Although coliforms were not found, the bacterial species associated with the tissues of crabs collected near Kodiak indicate possible fecal contamination that may have occurred through contact with sewage. Compared with surrounding waters and sediments, the crab tissues contained much higher proportions of gram-positive cocci. As revealed by indirect plate counts and direct scanning electron microscopic observations, muscle and hemolymph tissues contained much lower levels of bacteria than shell and gill tissues. After the death of a crab, however, the numbers of bacteria associated with hemolymph and muscle tissues increased significantly. Microcosm studies showed that certain bacterial populations, e.g., Vibrio cholerae, can be bioaccumulated in crab gill tissues. The results of this study indicate the need for careful review of waste disposal practices where edible crabs may be contaminated with microorganisms that are potential human pathogens and the need for surveillance of shellfish for pathogenic microorganisms that naturally occur in marine ecosystems.
Three entirely different tumor types were investigated biochemically for the presence and characteristics of endogenous carbohydrate-binding proteins in an inbred Brown Norway rat, an outbred Sprague-Dawley rat, and an outbred Han:NMRI mouse. The patterns under investigation included specificities for alpha- and beta-galactosyl, alpha-mannosyl, and alpha-fucosyl moieties, respectively, and specificities for heparin, analyzed by affinity chromatography on resins with immobilized sugars or glycoproteins and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The patterns were divided into categories according to dependence of the binding activity on the presence of Ca2+ and dependence on extraction conditions. Rhabdomyosarcoma revealed only Ca2+-independent activities, i.e., activities with specificity for beta-galactosides at a molecular weight of 12,000, with specificity for alpha-galactosides at molecular weights of 29,000, 43,000, and 45,000, with specificity for heparin at molecular weights of 13,000 and 16,000, and with specificities for mannose and fucose at molecular weights ranging from 62,000 to 70,000. For the spontaneous mammary adenocarcinoma the pattern was entirely different and more diverse, including species with the Ca2+ requirement. Extracts with the use of 0.2 M NaCl (salt) and 2% Triton X-100 (detergent) from teratoma contained at least nine different carbohydrate-binding proteins. The only similarities between the pattern of endogenous carbohydrate-binding proteins from teratoma and from mammary adenocarcinoma were beta-galactoside-binding proteins, one with a Ca2+ requirement and one without a Ca2+ requirement, and the heparin-binding proteins. These heparin-binding proteins were the only types of carbohydrate-binding proteins common to all three tumor types. The analysis indicates that certain bands represented newly identified proteins capable of binding to galactose-, mannose- or fucose-containing glycoconjugates, respectively. When assayed with rabbit erythrocytes, the different fractions showed agglutination activity. They can thus be termed "endogenous lectins." The use of endogenous lectin patterns as potential diagnostic markers in addition to the corresponding changes in the glycoconjugate composition is proposed.
I-compounds are species-, tissue-, genotype-, gender-, and diet-dependent bulky DNA modifications whose levels increase with animal age. While a few of these DNA modifications represent oxidation products, the majority of I-compounds appear to be derived from as yet unidentified endogenous DNA-reactive intermediates other than reactive oxygen species. Circadian rhythms of certain I-compounds in rodent liver imply that levels of these DNA modifications are precisely regulated. Caloric restriction (CR), the currently most effective method available to retard aging and carcinogenesis, has been previously shown to elicit significant elevations of I-compound levels in tissue DNA from Brown-Norway (BN) and F-344 rats as compared to age-matched ad libitum fed (AL) animals. The present investigation has extended this work by examining liver and kidney DNA I-compound levels in three genotypes of rats (F-344, BN, and F-344 x BN) and two genotypes of mice (C57BL/6N and B6D2F1) under identical experimental conditions in order to determine whether correlations exist between I-compound levels, measured in middle-aged animals, and median lifespan. Levels of a number of liver and kidney I-compounds were found to display genotype- and diet-dependent, statistically significant positive linear correlations with median lifespan in both species. In particular, the longer-lived hybrid F-344 x BN rats and B6D2F1 mice tended to exhibit higher I-compound levels than the parent strains. CR enhanced I-compound levels substantially in both rats and mice. Thus, I-compounds, measured at middle age, reflected the functional capability ('health') of the organism at old age, suggesting their predictive value as biomarkers of aging. The positive linear correlations between levels of certain I-compounds (designated as type I) and lifespan suggest that these modifications may be functionally important and thus not represent endogenous DNA lesions (type II), whose levels would be expected to correlate inversely with lifespan.
Idiosyncratic drug reactions are difficult to study in humans due to their unpredictability. Unfortunately, this characteristic also hinders the development of animal models needed for mechanistic studies. Nevirapine, used to treat human immunodeficiency virus (HIV) infections, results in a severe idiosyncratic skin rash in some patients. We found that nevirapine can also cause a significant rash in some strains of rats. At a dose of 150 mg/kg/day, the incidence in female Sprague-Dawley rats was 6/28 (21%), in female Brown Norway rats 32/32 (100%), and in female Lewis rats 0/6 (0%) while no male Sprague-Dawley or Brown Norway rats developed a rash. Female SJL mice 0/7 also did not develop nevirapine-induced skin lesions. The first sign of a reaction in Brown Norway rats was red ears at days 7-10 followed by a rash with scabbing mainly on the back; this was a shorter time to onset than in Sprague-Dawley rats. Light microscopy of the skin revealed a primarily mononuclear inflammatory infiltrate and lesions typical of self-trauma. Immunohistochemistry results suggest that the infiltrate was composed of CD4 and CD8 T cells as well as macrophages. A lower dose of either 40 or 75 mg/kg/day did not lead to a rash and, in fact, 2 weeks of the lower doses induced tolerance to the 150 mg/kg/day dose in female Brown Norway rats. A dose of 100 mg/kg/day resulted in rash in 2/4 (50%) of female Brown Norway rats. Rechallenge of Brown Norway rats that had been allowed to recuperate after a nevirapine-induced rash led to red ears in less than 24 h followed by hair loss and occasional skin lesions. Although the skin rash was less evident on rechallenge, microscopically, the cellular infiltrate was more prominent, especially surrounding the hair follicles. Moreover, there were lesions of interface dermatitis with apoptosis and satellitosis, indicative of a cell-mediated immune attack on the epidermis. While systemic signs of illness did not accompany the rash on primary exposure, on rechallenge, the animals appeared generally unwell and this forced sacrifice after 2 weeks or less of treatment. Importantly, splenocytes isolated from rechallenged animals were able to transfer susceptibility to nevirapine-induced skin rash to naïve female Brown Norway recipients, which was illustrated by a faster time to onset of rash in the recipients. The characteristics of this adverse reaction are similar to that seen in humans; that is, it is idiosyncratic in that it only occurs in some strains of animals, is delayed in onset, is more common in females, is dose-dependent, and appears to be immune-mediated. Therefore, it may represent a good animal model for the study of idiosyncratic drug reactions.
Viruses of the tick-borne encephalitis (TBE) antigenic complex, within the family Flaviviridae, cause a variety of diseases including uncomplicated febrile illness, encephalitis, meningo-encephalitis, hemorrhagic fever and chronic disease in humans, domesticated animals or wildlife species. TBE is a serious problem in Latvia with up to a 1,000 patients confirmed serologically annually 1994-1995. No previous data had been reported on the causative agent of TBE in Latvia. In the present study, a virus was isolated from serum of a patient with clinical symptoms of an acute TBE infection. Nucleotide sequence information obtained by direct reverse transcription-polymerase chain reaction (RT-PCR) and the serological characteristics of the isolated virus strain, designated TBE-Latvia-1-96, indicated a closer relationship to the Vasilchenko strain, isolated in Novosibirsk (Siberia, Russia), as compared to the western European or far eastern subtypes of TBE viruses. In a mouse neurovirulence assay, a significant difference in survival rates (days) was shown between Latvia-1-96 and the western European TBE virus subtype.