DNA transfection of a gene repressing aryl hydrocarbon hydroxylase induction

High mol. wt genomic DNA from a genetically dominant aryl hydrocarbonhydroxylase (AHH)-deficient mutant cell line derived from themouse hepatoma cell line Hepa-1 was used to transfect the parentcell line. AHH-deficient transfectants were recovered followingsingle-step selection in medium containing the carcinogen benzo(a)pyrene.The transfectants arose at a frequency of 2 x 10^–7. Thisfrequency was at least 4-fold greater than the frequency ofspontaneous forward mutation in this cell line. In another setof experiments, dominant mutant DNA was co-transfected alongwith the selectable plasmid pSV2ecogpt into parental Hepa-1cells. The frequency of co-transfection was determined to be3 x 10^–8. This frequency was 150 times greater than thatexpected on the basis of coincident but unrelated spontaneousmutation and plasmid uptake. Both types of transfectants werejudged, following somatic cell hybridizations, to possess thedominant phenotype of the mutant cell line, demonstrating thata trans-acting dominant negative regulator of AHH was transferredin these experiments. DNA transfection should therefore providea means for the molecular cloning of the gene that encodes thedominant regulator.     

Impaired microtubule function correctable by cyclic GMP and cholinergic agonists in the Chediak-Higashi syndrome.

The Chediak-Higashi (CH) syndrome of man and several animal species is characterized by the presence of abnormal giant granules in all granule-containing cells and by defects in chemotaxis and lysosomal degranulation during phagocytosis in polymorphonuclear leukocytes (PMNs). Since similar functional abnormalities have been reported in normal PMNs following exposure to colchicine and other agents that disrupt microtubles it was proposed that microtubule function may be impaired in the CH syndrome. The mobility of concanavalin A (con A)-receptor complexes on PMN membranes was used to test microtubule integrity. Normal PMNs showed a uniform distribution of membrane-bound con A. By contrast, con A was aggregated into surface caps on both colchicine-treated normal PMNs and untreated PMNs from mice and a patient with CH syndrome. This result is consistent with impaired microtubule function in the CH cells. The spontaneous capping response of CH PMNs was inhibited by cyclic GMP and by cholinergic agonists that can elevate cyclic GMP levels in neutrophils. This raised the possibility that the microtubule defect in CH cells may be correctable by treatments that increase cyclic GMP generation. Direct evidence for both the absence of microtubule assembly in con A-treated PMNs from the CH patient and for normal microtubule assembly in CH PMNs incubated with cyclic GMP and cholinergic agonists prior to con A treatment was obtained by electron microscopy. In addition, evidence for a direct relationship between the microtubule defect and the development of giant lysosomes in CH cells was obtained. Thus, CH fibroblasts grown in vitro developed abnormal lysosomes in the majority of cells. However, the same cells cultured in the presence of cholinergic agonists developed a majority of lysosomes that were morphologically normal at the level of the light microscope. Similarly, granule morphology appeared normal in peripheral blood leukocytes from mice treated chronically in vivo with cholinergic agonists.     

Investigations on the biology,epidemiology, pathology and control of<Emphasis Type="Italic"> Tunga penetrans</Emphasis> in Brazil: I. Natural history of tungiasis in man

Tungiasis is an important health problem in poor communities in Brazil and is associated with severe morbidity, particularly in children. The causative agent, the female flea Tunga penetrans, burrows into the skin of its host, where it develops, produces eggs and eventually dies. From the beginning of the penetration to the elimination of the carcass of the ectoparasite by skin repair mechanisms, the whole process takes 4-6 weeks. The present study is based on specimens from 86 patients, for some of whom the exact time of penetration was known. Lesions were photographed, described in detail and biopsied. Biopsies were examined histologically and by means of scanning electron microscopy (SEM). Based on clinical, SEM and histological findings, the "Fortaleza classification" was elaborated. This allows the natural history of tungiasis to be divided into five stages: (1) the penetration phase, (2) the phase of beginning hypertrophy, (3) the white halo phase, (4) the involution phase and (5) residues in the host's skin. Based on morphological and functional criteria, stages 3 and 4 are divided into further substages. The proposed Fortaleza classification can be used for clinical and epidemiological purposes. It allows a more precise diagnosis, enables the assessment of chemotherapeutic approaches and helps to evaluate control measures at the community level.     

Dominant and recessive aryl hydrocarbon hydroxylase-deficient mutants of mouse hepatoma line,Hepa-1, and assignment of recessive mutants to three complementation groups

Fifty-four benzo[a]pyrene (BP)-resistant, aryl hydrocarbon hydroxylase (AHH)-deficient mutants were found to be recessive, while five were dominant. Hybrids between the former mutants and the wild-type were killed by BP, and possessed AHH activities of at least 0.5 (relative to the wild-type). Dominant-mutant-wild-type hybrids were resistant to BP and had activities of about 0.05. Additional experiments assigned the recessive mutants to three complementation groups, designated A through C. Group-B-group-C hybrids were exceptional in possessing a mean AHH activity (0.36), less than the value (0.5) expected from gene dosage. This deficiency was probably due, in part, to instability of AHH activity in these hybrids. However, all hybrids tested retained stable DNA complements, equal to the sum of those of their parents, for 140 days in culture. Previous studies have shown that group B and group C mutations both affect the functioning of a cytosolic receptor required for AHH induction (1).     

Evaluation of hyperforin analogues for inhibition of 5-lipoxygenase

The acylphloroglucinol hyperforin, a constituent of the herb Hypericum perforatum (St. John's wort), was recently identified as potent and direct inhibitor of 5-lipoxygenase (5-LO), the key enzyme in the biosynthesis of proinflammatory leukotrienes. In this study, naturally occurring analogues of hyperforin, isolated from H. perforatum, as well as a series of synthetic derivatives obtained by chemical modification of hyperforin by acylation, alkylation or oxidation, were analysed for the inhibition of 5-LO. The efficacies of these compounds were evaluated in intact human polymorphonuclear leukocytes, but also the inhibitory effects on isolated recombinant human 5-LO were investigated. Our data show that some of the oxidised hyperforin derivatives possess even improved efficacy, whereas alkylation and acylation have detrimental effects.     

Homozygous microdeletion of chromosome 4q11-q12 causes severe limb-girdle muscular dystrophy type 2E with joint hyperlaxity and contractures

Microdeletion syndromes are commonly transmitted as dominant traits and are frequently associated with variably expressed pleiotropic phenotypes. Nonlethal homozygous microdeletions, on the other hand, are very rare. Here, we delineate the fifth and so far largest homozygous microdeletion in nonmalignancies of approximately 400 kb on chromosome 4q11-q12 in a large consanguineous East-Anatolian family with six affected patients. The deleted region contains the beta-sarcoglycan gene (SGCB), the predicted gene SPATA18 (spermatogenesis associated 18 homolog) and several expressed sequence tags. Patients presented with a severe and progressive Duchenne-like muscular dystrophy phenotype, a combination of hyperlaxity and joint contractures, chest pain, palpitations, and dyspnea.     

Siderophore production by Vibrio vulnificus

Previous studies in our laboratory, as well as clinical evidence, have suggested that increased iron levels in the host may be important in infections caused by the halophilic pathogen Vibrio vulnificus. To study iron acquisition, we induced siderophore production by growth in a low-iron medium, and biochemical testing indicated the production of both hydroxamate- and phenolate-type siderophores. The siderophores were extracted from growth filtrates with ethyl acetate (for phenolates) and phenol-chloroform-ether (for hydroxamates). These extracts enhanced the growth of V. vulnificus when the bacterium was grown in iron-limited medium. The ability of these siderophores to stimulate the growth of Salmonella typhimurium LT-2 enb-7 (a mutant deficient in the biosynthesis of enterochelin) and Arthrobacter flavescens JG-9 (a hydroxamate auxotroph) supported the conclusion that V. vulnificus produces both hydroxamate- and phenolate-type siderophores.     

Age-related accumulation of ceroid-like pigment in mice with Chediak-Higashi syndrome.

The Chediak-Higashi Syndrome (CHS) is a rare inherited disorder occurring in man and several animal homologs including the beige mouse; it is characterized by pigmentary dilution, susceptibility to pyogenic infections, and the presence of enlarged lysosomes in many cell types. Beige mice 6 months of age and older were found to have darkened livers, kidneys, and spleens, accompanied by splenomegaly. A fluorescence microscopic survey of tissues from beige mice revealed marked accumulations of a microscopic survey of tissues from beige mice revealed marked accumulations of a yellow autofluorescent pigment inhepatocytes, renal proximal tubule cells, and splenic macrophages. Additionally, large amounts of hemosiderin were present in the spleen. In beige mice, the pigment was noted in animals as young as 1 to 2 weeks of age and gradually increased in amount as the animals aged. A histochemical investigation of the pigment showed that it was ceroid-like in nature and contained in lysosomes. Ultrastructurally, the pigment was composed of lipid-like droplets embedded in a dense matrix and surrounded by a limiting membrane. The accumulation of ceroid-like material in beige mice may be a reflection of the metabolic disturbance which underlies CHS.