VM Rodríguez  L Dufour  L Carrizales  F Díaz-Barriga  ME Jiménez-Capdeville 《Canadian Metallurgical Quarterly》1998,106(8):487-491

Several single components of mining waste (arsenic, manganese, lead, cadmium) to which humans are exposed at the mining area of Villa de la Paz, Mexico, are known to provoke alterations of striatal dopaminergic parameters. In this study we used an animal model to examine neurochemical changes resulting from exposure to a metal mixture. We used microdialysis to compare in vivo dopamine release from adult rats subchronically exposed to a mining waste by oral route with those from a control group and from a sodium arsenite group (25 mg/kg/day). We found that arsenic and manganese do accumulate in rat brain after 2 weeks of oral exposure. The mining waste group showed significantly decreased basal levels of dihydroxyphenylacetic acid (DOPAC; 66.7 +/- 7.53 pg/ microl) when compared to a control group (113.7 +/- 14.3 pg/ microl). Although basal dopamine release rates were comparable among groups, when the system was challenged with a long-standing depolarization through high-potassium perfusion, animals exposed to mining waste were not able to sustain an increased dopamine release in response to depolarization (mining waste group 5.5 +/- 0.5 pg/ microl versus control group 21.7 +/- 5.8 pg/ microl). Also, DOPAC and homovanillic acid levels were significantly lower in exposed animals than in controls during stimulation with high potassium. The arsenite group showed a similar tendency to that from the mining waste group. In vivo microdialysis provides relevant data about the effects of a chemical mixture. Our results indicate that this mining waste may represent a health risk for the exposed population.  相似文献   

    

M Diviné  F Reyes 《Canadian Metallurgical Quarterly》1998,48(10):1087-1091

BACKGROUND: Vascular anomalies (hemangiomas and vascular malformations) are frequently located in the oral cavity. They can be treated by cool steel surgery, cryotherapy, laser therapy, embolization, and sclerosis. The choice of treatment should depend on the type of vascular anomaly, its site, the general condition of the patient, and the doctor's experience. OBJECTIVE: The objective of this article is to assess the usefulness, indications, and advantages of transfixion technique in the treatment of oral vascular lesions. METHODS: We present seven patients with various vascular anomalies in the oral cavity that were treated using transfixion technique. This procedure is performed with local infiltration anesthesia and it consists of interlacing a polyglycolic acid suture a number of times in an upward direction until the vascular anomaly becomes bloodless. RESULTS: In all seven patients we completely eliminated the vascular lesion without significant long-term complications. We detected a transitory retractil scar in only one patient and edema in the postoperative period in another one. CONCLUSIONS: Treatment of vascular anomalies of the oral cavity by transfixion technique is an effective, simple method that does not cause major complications and is low in cost.  相似文献   

    

S Baqué  E Montell  M Camps  JJ Guinovart  A Zorzano  AM Gómez-Foix 《Canadian Metallurgical Quarterly》1998,47(8):1185-1192

Skeletal muscle glucose utilization, a major factor in the control of whole-body glucose tolerance, is modulated in accordance with the muscle metabolic demand. For instance, it is increased in chronic contraction or exercise training in association with elevated expression of GLUT4 and hexokinase II (HK-II). In this work, the contribution of increased metabolic flux to the regulation of the glucose transport capacity was analyzed in cultured human skeletal muscle engineered to overexpress glycogen phosphorylase (GP). Myocytes treated with an adenovirus-bearing muscle GP cDNA (AdCMV-MGP) expressed 10 times higher GP activity and exhibited a twofold increase in the Vmax for 2-deoxy-D-[3H]glucose (2-DG) uptake, with no effect on the apparent Km. The stimulatory effect of insulin on 2-DG uptake was also markedly enhanced in AdCMV-MGP-treated cells, which showed maximal insulin stimulation 2.8 times higher than control cells. No changes in HKII total activity or the intracellular compartmentalization were found. GLUT4, protein, and mRNA were raised in AdCMV-MGP-treated cells, suggesting pretranslational activation. GLUT4 was immunodetected intracellularly with a perinuclear predominance. Culture in glucose-free or high-glucose medium did not alter GLUT4 protein content in either control cells or AdCMV-MGP-treated cells. Control and GP-overexpressing cells showed similar autoinhibition of glucose transport, although they appeared to differ in the mechanism(s) involved in this effect. Whereas GLUT1 protein increased in control cells when they were switched from a high-glucose to a glucose-free medium, GLUT1 remained unaltered in GP-expressing cells upon glucose deprivation. Therefore, the increased intracellular metabolic (glycogenolytic-glycolytic) flux that occurs in muscle cells overexpressing GP causes an increase in GLUT4 expression and enhances basal and insulin-stimulated glucose transport, without significant changes in the autoinhibition of glucose transport. This mechanism of regulation may be operative in the postexercise situation in which GLUT4 expression is upregulated in coordination with increased glycolytic flux and energy demand.  相似文献   

    

R Torres-Jiménez  F Mateos-Antón  J Arcas-Martínez  I Pascual-Castroviejo  J García-Puig 《Canadian Metallurgical Quarterly》1998,27(160):1050-1054

OBJECTIVE: Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency is characterized by an increase in renal uric acid excretion, usually with hyperuricemia and may be associated with more or less important neurological symptoms. Based on a series of 20 patients from 16 Spanish families we propose that HPRT deficiency could be clinically classified in four different groups. In the more severe form (classic Lesch-Nyhan syndrome) HPRT deficiency is characterized by choreoathetosis, spasticity, mental retardation and compulsive self-mutilation behavior. The pathophysiology of the neurological symptoms remains unclear and there is no effective therapy. This review is intended to provide a research strategy for a better knowledge of the neurological pathophysiology of HPRT deficiency. DEVELOPMENT: We have analyzed the knowledge on the neurological symptoms of HPRT deficiency. This knowledge comes from histopathological studies of the brains from Lesch-Nyhan patients, chemical studies of the cerebrospinal fluid, experimental animal models (pharmacologic and lesioning and genetic approaches), and human in vivo studies with positron-emission tomography. CONCLUSIONS: The observed findings suggest that the neurological symptoms of Lesch-Nyhan syndrome could be related with the neonatal neuronal and/or dopaminergic terminations damage. This damage could be due to lost or reorganization of dopaminergic system, and is associated with a reduced dopamine levels and with hypersensitivity of the D1 subclass dopamine receptors.  相似文献   

    

H Tlaskalová-Hogenová  R St?pánková  L Tucková  MA Farré  DP Funda  EF Verdú  J Sinkora  T Hudcovic  Z Reháková  B Cukrowska  H Kozáková  L Prokesová 《Canadian Metallurgical Quarterly》1998,43(5):545-550

Despite the fact that target antigens and the genetic basis of several autoimmune diseases are now better understood, the initial events leading to a loss of tolerance towards self-components remain unknown. One of the most attractive explanations for autoimmune phenomena involves various infections as possible natural events capable of initiating the process in genetically predisposed individuals. The most accepted explanation of how infection causes autoimmunity is based on the concept of \"molecular mimicry\" (similarity between the epitopes of an autoantigen and the epitopes in the environmental antigen). Infectious stimuli may also participate in the development of autoimmunity by inducing an increased expression of stress proteins (hsp), chaperones and transplantation antigens, which leads to abnormal processing and presentation of self antigens. Superantigens are considered to be one of the most effective bacterial components to induce inflammatory reactions and to take part in the development and course of autoimmune mechanisms. It has long been known that defects in the host defense mechanism render the individual susceptible to infections caused by certain microorganisms. Impaired exclusion of microbial antigens can lead to chronic immunological activation which can affect the tolerance to self components. Defects in certain components of the immune system are associated with a higher risk of a development of autoimmune disease. The use of animal models for the studies of human diseases with immunological pathogenesis has provided new insights into the influence of immunoregulatory factors and the lymphocyte subsets involved in the development of disease. One of the most striking conclusion arising from work with genetically engineered immunodeficient mouse models is the existence of a high level of redundancy of the components of the immune system. However, when genes encoding molecules involved in T cell immunoregulatory functions are deleted, spontaneous chronic inflammation of the gut mucosa (similar to human inflammatory bowel disease) develops. Surprisingly, when such immunocompromised animals were placed into germfree environment, intestinal inflammation did not develop. Impairment of the mucosal immune response to the normal bacterial flora has been proposed to play a crucial role in the pathogenesis of chronic intestinal inflammation. The use of immunodeficient models colonized with defined microflora for the analysis of immune reactivity will shed light on the mode of action of different immunologically important molecules responsible for the delicate balance between luminal commensals, nonspecific and specific components of the mucosal immune system.  相似文献   

    

A Jiménez Verdejo  M Arrabal Martín  J Miján Ortiz  J Sánchez Tamayo  F López-Carmona Pintado  A Zuluaga Gómez 《Canadian Metallurgical Quarterly》1998,51(7):709-715

OBJECTIVE: To describe the efficacy of extracorporeal shock wave lithotripsy in the treatment of lithiasis in patients with solitary functioning kidney. METHODS: The study comprised 56 patients with solitary kidney that had been treated by extracorporeal shock wave lithotripsy. These patients had a solitary kidney for the following reasons: 30 had undergone nephrectomy due to lithiasis, 11 had lost renal function arising from lithiasis, 9 had undergone nephrectomy for other pathologies and 6 had renal agenesis. Nine stone variables and treatment were analyzed. The same variables were analyzed and compared for statistical significance in a representative sample of 125 lithiasic patients with two kidneys who were treated by ESWL. RESULTS: Patients with solitary kidney frequently had a single calculus of < or = 1 cm located in calyces, unobstructive and did not require complementary endourological procedures. The mean number of shock waves was 8535. The psot-lithotripsy success rate was 82.1%; 98.2% had no complications. Comparison of these variables in both groups of patients showed statistically significant differences for stone location, indication for complementary endourological procedures and the number of shock waves utilized. CONCLUSIONS: In our view, ESWL is the treatment of choice in patients with lithiasis in a solitary kidney due to its high success rate and low morbidity. Stringent criteria must be employed before indicating prior endourological procedures to preserve the patency of the excretory tract and to minimize the risk of ureteral obstruction.  相似文献   

    

R Cortés  G Mengod  P Celada  F Artigas 《Canadian Metallurgical Quarterly》1993,60(2):761-764

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P Adelroth  K Lindberg  LE Andréasson 《Canadian Metallurgical Quarterly》1995,34(28):9021-9027

The Ca(2+)-binding properties of photosystem II were investigated with radioactive 45Ca2+. PS II membranes, isolated from spinach grown on a medium containing 45Ca2+, contained 1.5 Ca2+ per PS II unit. Approximately half of the incorporated radioactivity was lost after incubation for 30 h in nonradioactive buffer. About 1 Ca2+/PS II bound slowly to Ca(2+)-depleted membranes in the presence of the extrinsic 16- and 23-kDa polypeptides in parallel with restoration of oxygen-evolving activity. The binding was heterogeneous with dissociation constants of 60 microM (0.7 Ca2+/PS II) and 1.7 mM (0.3 Ca2+/PS II), respectively, which could reflect different affinities of the dark-stable S-states for Ca2+. The reactivation of oxygen-evolving activity closely followed the binding of Ca2+, showing that a single exchangeable Ca2+ per PS II is sufficient for the water-splitting reaction to function. In PS II, depleted of the 16- and 23-kDa polypeptides, about 0.7 exchangeable Ca2+/PS II binds with a dissociation constant of 26 microM, while 0.3 Ca2+ binds with a much weaker affinity (Kd > 0.5 mM). The rate of binding of Ca2+ in the absence of the two extrinsic polypeptides was significantly higher than with the polypeptides bound. The rate of dissociation of bound Ca2+ in the dark, which had a half-time of about 80 h in intact PS II, increased in the absence of the 16- and 23-kDa polypeptides and showed a further increase after the additional removal of the 33-kDa protein and manganese. The rate of dissociation was also significantly faster in weak light than in the dark regardless of the presence or absence of the 16- and 23-kDa polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

    

C Felgines  C Sérougne  A Mazur  J Férézou  C Lutton  Y Rayssiguier 《Canadian Metallurgical Quarterly》1995,117(1):15-24

Up and down-regulation of calcium and potassium conductances are associated with several forms of short-term synaptic modulation. Detailed investigation of synaptic plasticity in the marine gastropod Aplysia, and in other mollusks, indicates that synaptic transmission can be influenced in a number of ways by modulatory neurotransmitters acting through several second-messenger cascades. Modulation at the synapse itself occurs by means of the regulation of calcium current as well as through effects on processes directly involved in transmitter mobilization and exocytosis. Modulation of potassium current plays a major role in controlling neuronal excitability and may contribute to a lesser extent to the regulation of transmitter release through actions on the resting potential and on action potential configuration.  相似文献   

    

C Pérot  MI Almeida-Silveira 《Canadian Metallurgical Quarterly》1994,51(1):71-76

Homozygotic spasmodic (spd/spd) mice suffer from a motor disorder resembling poisoning by the glycine receptor antagonist strychnine. Here, a point mutation was identified in the glycine receptor alpha 1 subunit gene of the spasmodic mouse which predicts an alanine-to-serine exchange at position 52 of the mature polypeptide. Upon expression in Xenopus laevis oocytes, alpha 1A52S receptor channels displayed reduced responses to glycine, beta-alanine and taurine when compared to recombinant alpha 1 glycine receptors. As glycine receptor content in spinal cord and native molecular weight appeared unaltered, this suggests that the spasmodic phenotype results from an altered neurotransmitter sensitivity of the mutant alpha 1A52S subunit.  相似文献