RESUMEN
Research in the field of assisted reproduction technologies (ART) is today very active internationally and is aimed both at improving success chances of already consolidated techniques (in fact these chances are still considerably low), and at elaborating new methods like ICSI (intracytoplasmic sperm injection), oocyte cryoconservation, ovary tissue cultures. Some other techniques, connected to ART, are here considered, like preimplantation diagnosis, early sex determination, gene therapy in utero and cloning. All these subjects of research are here briefly mentioned in relation to the ethical debate which they have stirred or which they should stir according to the authors. These debates are in part mirrored in the different legislations.
Asunto(s)
Bioética , Inseminación Artificial/normas , Clonación de Organismos , Criopreservación , Transferencia de Embrión/normas , Fertilización In Vitro/legislación & jurisprudencia , Fertilización In Vitro/normas , Terapia Genética , Humanos , Inseminación Artificial/legislación & jurisprudencia , Inseminación Artificial/métodos , Óvulo , Diagnóstico Preimplantación , Investigación , Análisis para Determinación del SexoRESUMEN
IDPN-induced changes in a variety of sensory, motor and autonomic nerves were studied by whole-mount immunocytochemistry. A full range of proximo-distal accumulations of neurofilament-like material was found, from paranuclear round bodies in perikarya to distal and preterminal axonal dilations. Conversely, both terminal areas and nodal-paranodal regions of myelinated axons showed striking, sharply localized loss of neurofilament-immunostaining. The latter change, when transport of neurofilaments is halted by IDPN, may indicate their local processing and/or differential transport at nodal-paranodal regions.
Asunto(s)
Sistema Nervioso Autónomo/química , Filamentos Intermedios/química , Neuronas Motoras/química , Enfermedades del Sistema Nervioso/metabolismo , Neuronas Aferentes/química , Animales , Inmunohistoquímica , Masculino , Enfermedades del Sistema Nervioso/inducido químicamente , Neurotoxinas , Nitrilos , Ratas , Ratas Sprague-DawleyRESUMEN
Sixty-day-old virgin female Swiss CD1 mice were treated with 1.5% 2,5-hexanedione in their drinking water; control mice received tap water; duration of treatment was either 4 or 6 weeks. Under these conditions the treated mice did not show any clinical symptoms although electromyography revealed some signs of polyneuropathy. Protein and DNA content per mg of ovarian tissue in treated mice were not significantly different from controls. Histological examination of ovarian sections at the light microscope level showed no significant alterations after exposure. A morphometric study revealed a statistically significant reduction in the number of growing oocytes after 6 weeks of treatment. For fertility studies three groups of 15 female mice each were treated for 0, 4 or 6 weeks as above and then permanently housed with untreated proven breeder male mice (one male per female); cages were checked daily for newly born mice. All litters appeared normal by gross examination. During the first 14 weeks of continuous mating the mean litter size (number of newborns per litter) remained about 11.4 in all groups; this number subsequently began to decrease. Control and 4-week treatment regression curves did not differ statistically, while the slope of the 6-week line was significantly steeper, indicating a faster decrease in litter size over time and a shortening of fertile life in the latter group of treated females.
Asunto(s)
Fertilidad/efectos de los fármacos , Hexanonas/toxicidad , Ovario/efectos de los fármacos , Animales , Peso Corporal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Electromiografía , Femenino , Masculino , Ratones , Microscopía , Enfermedades del Sistema Nervioso/inducido químicamente , Ovario/citología , Factores de TiempoRESUMEN
A variety of visceral nerves were studied by intermediate filament immunocytochemistry in rats intoxicated with acrylamide. In such animals, oesophageal and diaphragmatic motor end-plates were invaded and deformed by neurofilament protein-like material, while afferent fibres of diaphragmatic neuromuscular spindles and myelinated sensory fibres of the iris showed striking terminal accumulation of similar material. Conversely, the rich population of thin afferent fibres of the iris showed no obvious abnormality, while pre-terminal changes were seen along the extrinsic nerve fibres supplying the cornea and myenteric ganglia. Multiple lesions were demonstrated in gut nerves of acrylamide-treated rats, while scattered "enteric glial cells" showed abnormally coarse morphology and a striking increase in glial fibrillary acidic protein immunoreactivity. A distinct, delicately varicose appearance was revealed by neurofilament protein-immunostaining in bladder nerve fibres of normal rats, which was changed to one of coarse dilations by acrylamide. In conclusion, apparently selective changes were found along different types of axons, indicating marked heterogeneity in cytoskeletal organisation among visceral nerves. Taken together with the proposed inhibition by acrylamide of neurofilament proteins degradation, the above findings may suggest a non-uniform distribution of neurofilament degradation sites along distal regions of different axons.
Asunto(s)
Acrilamidas/toxicidad , Vías Aferentes/efectos de los fármacos , Sistema Nervioso Autónomo/efectos de los fármacos , Bronquios/inervación , Diafragma/inervación , Sistema Digestivo/inervación , Fibras Nerviosas/efectos de los fármacos , Neuronas/efectos de los fármacos , Tráquea/inervación , Uréter/inervación , Vejiga Urinaria/inervación , Acrilamida , Vías Aferentes/patología , Animales , Sistema Nervioso Autónomo/patología , Ojo/inervación , Técnica del Anticuerpo Fluorescente , Masculino , Fibras Nerviosas/ultraestructura , Proteínas de Neurofilamentos/análisis , Neuronas/patología , Ratas , Ratas Endogámicas , Tubulina (Proteína)/análisisRESUMEN
The effects of 2,5-hexanedione (2,5 HD) on skeletal proteins of red blood cells (RBCs) were investigated both in vitro (human RBCs) and in vivo in male Sprague-Dawley rats which had been treated with the drug for several days. We found that 2,5 HD induced the following major changes in the electrophoretic pattern of the skeletal proteins: (i) the appearance of high-molecular weight bands, (ii) a dose-dependent decrease in spectrin Bands 1 and 2, and (iii) a dose-dependent increase in the amount of hemoglobin (Hb) associated with the membrane. Membranoskeletons, prepared from resealed ghosts which had been previously treated with 2,5 HD, were able to bind an increased amount of Hb from untreated RBCs, thus suggesting a drug-induced modification of the membrane. Extraction of spectrin and actin from ghosts did not remove the membrane-bound Hb and, furthermore, Hb bound to 2,5 HD-treated membranes mainly bearing Band 3 and free of peripheral proteins. These data suggested a 2,5 HD-induced modification of an intrinsic membrane protein, probably Band 3. This hypothesis was consistent with the observation that 2,5 HD also induced a modification of Band 3 aminogroups, as evidenced by a dose-dependent decrease in the binding of eosin probes. Furthermore, RBCs treated in vitro with 2,5 HD bound an increased amount of autologous immunoglobulins (IgG). As reported by Kay and Low et al. the binding of autologous IgG is a phenomenon associated with the aging process of RBCs and may involve a modification of Band 3. Our data show that RBCs treated with 2,5 HD acquired various characteristics of senescent cells such as spectrin cross-linking, Hb-membrane binding and increased IgG binding, and suggest that 2,5 HD treatment might affect RBC survival.
Asunto(s)
Proteínas Sanguíneas/efectos de los fármacos , Eritrocitos/efectos de los fármacos , Hemoglobinas/metabolismo , Hexanonas/farmacología , Cetonas/farmacología , Animales , Proteínas Sanguíneas/metabolismo , Electroforesis en Gel de Poliacrilamida , Envejecimiento Eritrocítico/efectos de los fármacos , Membrana Eritrocítica/metabolismo , Eritrocitos/citología , Eritrocitos/metabolismo , Humanos , Técnicas In Vitro , Masculino , Unión Proteica/efectos de los fármacos , Ratas , Ratas EndogámicasRESUMEN
In rats intoxicated with 2,5-hexanedione, nerve fibres supplying virtually all visceral organs showed large numbers of densely immunoreactive accumulations of neurofilament-like material, of fusiform, elongated, smoothly tapering morphology. In the gut, round to oval, morphologically different lesions were also present, and abnormal neurofilament-immunoreactive accumulations were revealed in oesophageal terminal end-plates. An extensive damage to autonomic nerve fibres, which are largely non-myelinated, was thus revealed in 2,5-hexanedione intoxication. The observed diversity in lesion morphology may suggest heterogeneity in cytoskeletal and/or associated proteins among autonomic neurons.
Asunto(s)
Sistema Nervioso Autónomo/inmunología , Hexanonas/farmacología , Proteínas de Filamentos Intermediarios/inmunología , Cetonas/farmacología , Animales , Sistema Nervioso Autónomo/patología , Esófago/inervación , Hexanonas/envenenamiento , Inmunoquímica , Intestinos/inervación , Masculino , Fibras Nerviosas/inmunología , Fibras Nerviosas/patología , Proteínas de Neurofilamentos , Ratas , Ratas Endogámicas , Vísceras/inervaciónRESUMEN
Adult male rats were subjected to 4 weeks' respiratory treatment with n-hexane (5000 ppm, 16h/day, 6 days/week); motor conduction velocity was significantly decreased in tail nerves at all weekly intervals and did not approach normal values in the 4 weeks following interruption of treatment. Plasma acetylcholinesterase (AChE) levels were significantly increased at all weekly intervals during treatment (25-40%); 2 weeks after the end of treatment they had returned to baseline. Oral treatment with 2,5-hexanedione (HD) (1% in drinking water) caused a similar increase in plasma levels; this increase was statistically significant also when compared with pair-fed (PF) control rats. A sucrose density gradient analysis showed only one peak of AChE activity at approximately 10 S (as in normal plasma). The levels of butyrylcholinesterase were unaltered in plasma of both n-hexane-and HD-treated rats. Both the fast-contracting EDL and the slow-contracting soleus muscles lost weight in HD-treated rats with respect to free-fed (AL) and PF controls. AChE levels responded differently to HD treatment in the two muscle types: in EDL total extracts, AChE activity increased considerably with respect to AL controls (+ 70%, p less than 0.001), while the levels of the 16 S and 4 S molecular forms were unaltered. The increased levels of AChE found in plasma of rats intoxicated with n-hexane or with its metabolite HD may originate from muscle and correspond to an increased secretion of this molecular form.
Asunto(s)
Colinesterasas/análisis , Hexanos/toxicidad , Hexanonas/toxicidad , Cetonas/toxicidad , Animales , Centrifugación por Gradiente de Densidad , Colinesterasas/sangre , Electroforesis en Gel de Poliacrilamida , Hígado/enzimología , Masculino , Monitoreo Fisiológico , Actividad Motora/efectos de los fármacos , Músculos/enzimología , Ratas , Ratas Endogámicas , Respiración/efectos de los fármacosRESUMEN
Testicular damage was induced in rats by respiratory treatment with n-hexane at a concentration of 5000 ppm. The earliest lesions were observed immediately after 24 hr of continuous treatment, and involved primary spermatocytes from the leptotene to the middle pachitene stages and spermatids at late stages of maturation; at the same time numerous exfoliated, injured germ cells reached the epididymis. After the 24-hr treatment was suspended, damage to the seminiferous epithelium increased for the first 7 days, while the epididymis showed also focal infiltration by inflammatory cells; recovery was completed from Days 14 to 30. Intermittent treatment (16 hr/day, 6 days/week) at the same concentration of 5000 ppm for up to 6 weeks induced progressive increases in testicular and epididymal lesions, which, after 5 weeks (when most animals began to show clinical symptoms of polyneuropathy), reached aplasia of the germinal epithelium involving also the spermatogonia. Recovery from clinical symptoms was not paralleled by a regression of testicular pathology. On the contrary, after interruption of the treatment, the testicular lesions became increasingly severe, up to complete atrophy of the seminiferous tubules, suggesting an irreversible sterility of the treated animals. Pair-fed controls did not show histological alterations of the testis or epididymis.
Asunto(s)
Hexanos/toxicidad , Testículo/efectos de los fármacos , Administración por Inhalación , Animales , Esquema de Medicación , Epidídimo/efectos de los fármacos , Epidídimo/patología , Masculino , Microscopía Electrónica , Ratas , Túbulos Seminíferos/efectos de los fármacos , Túbulos Seminíferos/patología , Testículo/patología , Factores de TiempoRESUMEN
Exposure to n-hexane, a component of many industrial solvent mixtures, is known to cause polyneuropathy in man. The concentration of metabolites in urine following exposure may be useful in biological monitoring. In a comparative study experimental animals (rat, rabbit and monkey) were subjected to single inhalatory treatments of 6, 12 and 24 h with 5,000 ppm of pure n-hexane. At the end of the treatments and at intervals thereafter, urine, and in rats also blood, were collected and analyzed for n-hexane and its metabolites. While the urine of rats contained 2-hexanol, 3-hexanol, methyl n-butyl ketone, 2,5-dimethylfuran, y-valerolactone and 2,5-hexanedione, rabbit and monkey urine were found to contain only 2-hexanedione, rabbit and monkey urine were to contain only 2-hexanol, 3-hexanol, methyl n-butyl ketone and 2,5-hexanedione. Within 72 h of the end of exposure, the principal metabolite was 2,5-dimethylfuran in rats and 2-hexanol in rabbits and monkeys. In all three species the excretion rates of methyl n-butyl ketone, 3-hexanol and 2-hexanol peaked several hours earlier than 2,5-hexanedione (and gamma-valerolactone and 2,5-dimethylfuran in rats). In all species 2,5-hexanedione was still detectable in urine 60 h following exposure. n-Hexane metabolites in rat blood were 2-hexanol, methyl-n-butyl ketone, 2,5-dimethylfuran and 2,4-hexanedione. The first two, as well as n-hexane itself, were found in maximum concentration immediately after termination of exposure, while 2,5-dimethylfuran and 2,5-hexanedione, with the longer exposure times, peaked some hours later. The data from urine collected at the end of exposure were compared with those obtained in a parallel study in humans occupationally exposed to a mixture of hexane isomers. Humans chronically exposed to 10-140 ppm n-hexane had 2,5-hexanedione concentrations in urine ranging from 0.4 to 21.7 mg/l, i.e., in the same proportion as rats exposed once for 6 or 12 h to 5,000 ppm.
Asunto(s)
Hexanos/metabolismo , Macaca mulatta/metabolismo , Macaca/metabolismo , Animales , Biotransformación , Semivida , Hexanos/orina , Hexanonas/metabolismo , Masculino , Conejos/metabolismo , Ratas , Ratas Endogámicas/metabolismo , Especificidad de la EspecieRESUMEN
Rats were intermittently exposed (9 to 10 h/d, 5 to 6 d/week) to controlled concentrations of single analytical grad solvents in ambient air. After periods ranging from 7 to 30 weeks the animals were perfused with glutaraldehyde and samples of nerves were processed for light microscopy of sections and of teased fibers. Animals treated with n-hexane at 5000 ppm (14 weeks) or 2500 ppm (30 weeks) developed the typical giant axonal degeneration already described in rats treated continuously with 400 to 600 ppm of the same solvent for 7 weeks or more. No such alterations were found in rats subjected to the following intermittent respiratory treatments: n-hexane 500 ppm (30 weeks) or 1500 ppm (14 weeks), cyclohexane 1500 or 2500 (30 weeks), n-pentane 3000 ppm (30 weeks), n-heptane 1500 ppm (30 weeks), 2-methylpentane 1500 ppm (14 weeks), and 3-methylpentane 1500 ppm (14 weeks). The following metabolites were found in the urine of rats according to treatment (in parenthesis): 2-methyl-2-pentanol (2-methylpentane); 3-methyl-2-pentanol and 3-methyl-3-pentanol (3-methylpentane), 2-hexanol, 3-hexanol, gamma-valerolactone, 2,5-dimethylfuran, and 2,5-hexanedione (n-hexane). 2-Hexanol was found to be the main urinary metabolite of n-hexane, while 2,5-hexanedione was present only in a lesser proportion. This feature of rat metabolism suggests that in this species 2,5-hexanedione reaches an effective level at its site of action during intermittent respiratory treatment with n-hexane with difficulty and explains the high concentrations necessary to cause polyneuropathy in rats subjected to this treatment.
Asunto(s)
Adhesivos/toxicidad , Contaminantes Ocupacionales del Aire/toxicidad , Contaminantes Atmosféricos/toxicidad , Alcanos/toxicidad , Ciclohexanos/toxicidad , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Solventes/toxicidad , Contaminantes Ocupacionales del Aire/orina , Alcanos/orina , Animales , Axones/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Ciclohexanos/orina , Masculino , Ratas , Ratas Endogámicas , Solventes/orinaAsunto(s)
Contaminantes Ocupacionales del Aire , Contaminantes Atmosféricos , Alcanos/toxicidad , Cresoles/toxicidad , Neurotoxinas , Enfermedades Profesionales/inducido químicamente , Tritolilfosfatos/toxicidad , Acetilcolinesterasa/sangre , Alcanos/metabolismo , Animales , Aves , Butirilcolinesterasa/sangre , Gatos , Fenómenos Químicos , Química , Perros , Interacciones Farmacológicas , Eritrocitos/efectos de los fármacos , Eritrocitos/enzimología , Francia , Cobayas , Heptanos , Hexanos , Humanos , Macaca mulatta , Metil n-Butil Cetona/metabolismo , Microscopía Electrónica , Parálisis/inducido químicamente , Pentanos , Nervios Periféricos/ultraestructura , Fenobarbital/farmacología , Conejos , Ratas , Ovinos , Distribución Tisular , Tritolilfosfatos/metabolismo , Estados UnidosRESUMEN
The salient features of this method for biological monitoring of occupational exposure to organophosphorus insecticides are: (a) acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) are determined separately in whole haemolysed blood using specific substrates at appropriate concentrations; (b) 20 microliter of blood drawn from the finger tip is sufficient for both determinations; (c) the blood sample is immediately diluted with a solution of saponin and may thereafter be frozen for storage; (d) diagnostic kits, commercially available for the determination of plasma BuChE, may be employed with modifications; (e) the kinetic procedure is avoided by blocking the enzyme reactions at the end of the incubation period. This paper describes attempts to achieve optimal conditions for the two reactions. Under the conditions finally chosen, the whole blood 'AChE' activity value still includes a small percentage of plasma BuChE activity (12.5% of the total), while the whole blood 'BuChE' activity includes a small percentage of erythrocyte AChE activity (7% of the total). Results of determinations performed with this procedure on 172 healthy subjects are reported.
Asunto(s)
Acetilcolinesterasa/sangre , Butirilcolinesterasa/sangre , Colinesterasas/sangre , Adolescente , Adulto , Inhibidores de la Colinesterasa , Exposición a Riesgos Ambientales , Femenino , Humanos , Insecticidas , Masculino , Métodos , Persona de Mediana Edad , Compuestos Organofosforados , Fisostigmina/farmacología , Dodecil Sulfato de Sodio/farmacologíaRESUMEN
The aqueous extract of the venom glands of black widow spiders was fractionated on a column of Sephadex G-200 and then on a column of DEAE-Sephadex A-50 pH 8.2. A protein fraction was obtained that caused a great increase in the frequency of occurrence of miniature end plate potentials at the frog neuromuscular junction, and caused swelling of the nerve terminals and depleted them of their vesicles. The fraction consists of a least four protein components that are similar in their molecular weights (about 130,000) and isoelectric points (ranging from pH 5.2 to 5.5) and are immunologically indistinguishable. It contains no sugar residues and has little or no lipolytic or proteolytic activity. The fraction is toxic to mice and is different from the fractions that act on houseflies, the crayfish stretch receptor and the cockroach heart. It seems pure enough to warrant a detailed study of its site and mode of action.