RESUMEN
Mycobacterium paratuberculosis has been isolated from tissue taken from patients with Crohn's disease and has been implicated in the etiology of this disease. On culture, the organisms appear initially as cell wall-deficient, spheroplast-like forms that are difficult to identify by conventional techniques. Here we examine 30 unidentified cultures by the polymerase chain reaction using primers specific for M. paratuberculosis, Mycobacterium tuberculosis, and Mycobacterium avium restriction fragment length polymorphism type A/I and also by a non-species-specific mycobacterial polymerase chain reaction. Six of these cultures, all from Crohn's disease, were shown to contain DNA from M. paratuberculosis. Cultures from both Crohn's disease and controls were found to contain mycobacterial DNA of unknown specific origin.
Asunto(s)
Enfermedad de Crohn/microbiología , Mycobacterium/aislamiento & purificación , Paratuberculosis/microbiología , Esferoplastos/aislamiento & purificación , Secuencia de Bases , Enfermedad de Crohn/etiología , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Humanos , Datos de Secuencia Molecular , Mycobacterium/genética , Mycobacterium/patogenicidad , Reacción en Cadena de la Polimerasa/estadística & datos numéricos , Sensibilidad y EspecificidadRESUMEN
The nucleotide sequence of a swine vesicular disease virus (SVDV) strain that is pathogenic for pigs has been determined and compared with that of a non-pathogenic strain of SVDV, as well as a number of other enteroviruses. It shows only 98 base changes in comparison with a non-pathogenic strain of SVDV (Inoue et al., 1989, J. Gen. Virol. 70, 919-934). Fourteen of these nucleotide differences between the pathogenic and the non-pathogenic SVDV strains occur in the 5' non-coding region which, by analogy with the other picornaviruses, has been implicated in the efficiency with which the RNA is employed as mRNA. Additional differences found throughout the coding regions are largely conservative in nature. A number of residues are discussed as candidates for determinants of pathogenicity. This sequence has been submitted to the PIR database and has accession number A30061.
Asunto(s)
Enterovirus/genética , Enterovirus Porcinos/genética , Genes Virales , ARN Viral , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cápside/genética , Clonación Molecular , ADN Helicasas/genética , Enterovirus Porcinos/patogenicidad , Datos de Secuencia Molecular , Péptido Hidrolasas/genética , ARN Viral/aislamiento & purificación , Homología de Secuencia de Ácido Nucleico , Porcinos , Enfermedad Vesicular Porcina/microbiología , Proteínas Virales/genéticaRESUMEN
The role of melanocyte stimulating hormone (MSH) as a mediator of the melanogenic response to ultraviolet radiation (UVR) was examined in C57 BL/6 mice. While exposure to UVR (250-300 nm) for 7, 14 and 27 days increased tyrosinase activity in epidermal melanocytes of the ear MSH had no effect and failed to alter the response to UVR. Plasma alpha-MSH concentrations were unchanged following UVR. Theophylline, a phosphodiesterase inhibitor, also had no effect on epidermal tyrosinase activity in non-irradiated and UV irradiated mice. Prostaglandin E2 and arachidonic acid were also ineffective in non-irradiated and UV irradiated mice and indomethacin, an inhibitor of prostaglandin synthesis, failed to increase epidermal tyrosinase activity after UVR. On the other hand, 12-0-tetradecanoyl phorbol 13 acetate, an activator of protein kinase C, increased epidermal tyrosinase activity in non-irradiated mice and also enhanced the effect of UVR.
Asunto(s)
Células Epidérmicas , Hormonas Estimuladoras de los Melanocitos/farmacología , Melanocitos/efectos de la radiación , Monofenol Monooxigenasa/metabolismo , Rayos Ultravioleta , Animales , Ácido Araquidónico , Ácidos Araquidónicos/farmacología , Dinoprostona/farmacología , Relación Dosis-Respuesta a Droga , Activación Enzimática/efectos de los fármacos , Femenino , Indometacina/farmacología , Masculino , Hormonas Estimuladoras de los Melanocitos/sangre , Melanocitos/efectos de los fármacos , Melanocitos/enzimología , Ratones , Monofenol Monooxigenasa/efectos de la radiación , Proteína Quinasa C/metabolismo , Proteína Quinasa C/fisiología , Acetato de Tetradecanoilforbol/farmacología , Teofilina/farmacologíaRESUMEN
In this study, the effect of alpha-MSH on tyrosinase activity was compared in epidermal and hair follicular melanocytes of mice. It had no effect on epidermal tyrosinase activity in dorsal skin from neonatal non-agouti black mice (C57BL/6J) in both in-vivo and in-vitro experiments. Theophylline and 8-bromocyclic (c)AMP were similarly without effect in in-vitro experiments. In-vivo administration of alpha-MSH and theophylline for 7 days was also without effect on epidermal tyrosinase activity in ear skin of adult non-agouti mice, and the same was true for alpha-MSH in wild-type agouti mice. Activation of the epidermal melanocytes in the non-agouti and wild-type agouti mice with ultraviolet radiation also failed to bring about a response to alpha-MSH and to theophylline in the case of the former. No tyrosinase activity was detected in the epidermis of viable yellow mice (C3H-HeAvy), but, as shown previously, tyrosinase activity was present in the hair follicle when the hair was actively growing and was increased in those mice given either alpha-MSH or theophylline. alpha-MSH and theophylline had no such effects on hair follicular tyrosinase activity in the non-agouti mice. The present results suggest that alpha-MSH- and cAMP-dependent mechanisms have little or no importance in the regulation of tyrosinase expression in mouse epidermal melanocytes. alpha-MSH may, however, regulate tyrosinase expression in hair follicular melanocytes, but even in these melanocytes its action may be restricted to mice that express the agouti gene.
