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The molecular mechanisms regulating hemicelluloses and pectin biosynthesis are poorly understood. An important question in this regard is how glycosyltransferases are oriented in the Golgi cisternae, and how nucleotide sugars are made available for the synthesis of the polymers. Here we show that the branching enzyme xyloglucan alpha,1-2 fucosyltransferase (XG-FucTase) from growing pea (Pisum sativum) epicotyls was latent and protected against proteolytic inactivation on intact, right-side-in pea stem Golgi vesicles. Moreover, much of the XG-FucTase activity was membrane associated. These data indicate that XG-FucTase is a membrane-bound luminal enzyme. GDP-Fuc uptake studies demonstrated that GDP-Fuc was taken up into Golgi vesicles in a protein-mediated process, and that this uptake was not competed by UDP-Glc, suggesting that a specific GDP-Fuc transporter is involved in xyloglucan biosynthesis. Once in the lumen, Fuc was transferred onto endogenous acceptors, including xyloglucan. GDPase activity was detected in the lumen of the vesicles, suggesting than the GDP produced upon transfer of Fuc was hydrolyzed to GMP and inorganic phosphate. We suggest than the GDP-Fuc transporter and GDPase may be regulators of xyloglucan fucosylation in the Golgi apparatus from pea epicotyls.

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We report an eight years old boy presenting with a pyogenic granuloma of the scalp, generalized alopecia, descamative plates in the neck, trunk and limbs and nail involvement. Cultures for fungus of all these lesions disclosed Microspore canis. The patient was treated with oral griseofulvin, miconazole and topical tolnaftate. Five years later and after several incomplete treatments, the patient returns with a fistulous mass of 15 x 8 cm in the dorsal area whose culture revealed Microspore canis. The mass was excised and oral ketoconazole was indicated. After three months of follow up, the patient was lost from control.

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Golgi UDPase is an enzyme that has been shown to function in polysaccharide biosynthesis, but its role in this process is not yet clear. In this study we identified Golgi UDPase activity in pea (Pisum sativum) stems and differentiated it from another UDPase activity. We demonstrated that Golgi UDPase is an integral membrane protein, based on specific partitioning of this activity into Triton X-114. Analysis of its topology using sealed, right-side-out Golgi vesicles and treatment with proteinase K suggested that its active site faces the Golgi lumen. Studies aimed at understanding the function of Golgi UDPase by incubating Golgi vesicles with [beta]-32P]UDP-glucose (Glc) to generate [beta]-32P]UDP upon Glc transfer in situ showed that 32Pi, but not [beta]-32P]UDP, was formed, suggesting that UDPase quickly hydrolyzed the UDP formed during Glc polymerization. We found that the Golgi UDPase was highly active in the elongating region of the third internode, whereas no activity was detected in the first and second internodes of etiolated pea seedlings. These results suggest that UDPase removes the UDP formed during Glc polymerization and could be important in the mechanism of polysaccharide biosynthesis.

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The Golgi apparatus in plant cells is involved in hemicellulose and pectin biosynthesis. While it is known that glucan synthase I is responsible for the formation of [beta]-l-4-linked glucose (Glc) polymers and uses UDP-Glc as a substrate, very little is known about the topography of reactions leading to the biosynthesis of polysaccharides in this organelle. We isolated from pea (Pisum sativum) stems a fraction highly enriched in Golgi apparatus-derived vesicles that are sealed and have the same topographical orientation that the membranes have in vivo. Using these vesicles and UDP-Glc, we reconstituted polysaccharide biosynthesis in vitro and found evidence for a luminal location of the active site of glucan synthase I. In addition, we identified a UDP-Glc transport activity, which is likely to be involved in supplying substrate for glucan synthase I. We found that UDP-Glc transport is protein mediated. Moreover, our results suggest that UDP-Glc transport is coupled to the exit of a luminal uridine-containing nucleotide via an antiporter mechanism. We suggest that UDP-Glc is transported into the lumen of Golgi and that Glc is transferred to a polysaccharide chain, whereas the nucleotide moiety leaves the vesicle by an antiporter mechanism.

RESUMO

BACKGROUND: Mallory bodies are hepatocyte intracytoplasmic inclusions frequently observed in liver diseases. They contain altered intermediary filaments that have immunoreactivity with epidermic antikeratin antibodies (A-QEp). They also contain ubiquitin (Ubq) a 76 residue polypeptide that has an important role in the proteolysis of rapid exchange and abnormal cytosol proteins. AIM: To standardize an immunohistochemical method for the detection of Mallory bodies in percutaneous liver biopsies. METHODS: A-QEP and A-Ubq polyclonal antibodies were used in the study of 131 percutaneous liver biopsies obtained from patients with different liver diseases. Mallory body immunoreactivity was confirmed with immunoelectron microscopy. RESULTS: Mallory bodies had scanty immunostaining with A-QEp, specially in formalin fixed biopsies. There was a specific and sensitive staining with A-Uhq, that was not influenced by the fixation method. Immunoelectron microscopy demonstrated that Mallory bodies are partially formed by altered intermediate filaments. CONCLUSIONS: Antibodies against ubiquitin may be very useful for the detection of Mallory bodies in liver biopsies.

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El rol del citoesqueleto del hepatocito en secreción biliar y en la génesis de colestasia ha sido estudiado especialmente en relación a microfilamentos y microtúbulos, restándosele importancia los filamentos intermedios (FI). En cambio, estudios recientes han demostrado que la integridad de los FI del hepatocito es fundamental en la secreción biliar. Los FI del hepatocito corresponden a citoqueratinas y en ciertas patologías, especialmente de etiología alcohólica, éstos se alteran y en algunas ocasiones forman agregados como los cuerpos de Mallory (CM) cambiando sus características antigénicas. Se estudiaron 131 biopsias hepáticas con técnicas inmunohistoquímicas, utilizando sueros anti-queratinas epidérmicas y anti-ubiquitina, polipéptido de función proteolítica de proteínas anormales. De las biopsias estudiadas, 47 por ciento presentaban signos de colestasia y de éstas, un 64 por ciento presentó inmunorreacción en condensaciones pericanulares con anti-ubiquitina y un porcentaje algo menor con anti-queratinas; el resto de las biopsias fueron negativas con ambos anticuerpos. Estas observaciones indican que en biopsias hepáticas con signos de colestasia, las condensaciones pericaniculares correspondían a FI alterados, con características inmunogénicas semejantes a CM

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Se presenta un caso de adenocarcinoma mesonefroide de la uretra en un paciente de 63 años, tratada con exanteración pelviana anterior logrando una sobrevida de tres años. Se destaca la rareza de este tumor y se revisa la literatura

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Conventional preparation of goitrous hyperthyroid patients using lugol and propranolol may take 2 weeks. This period may be shortened using sodium iopodate and dexamethasone. We used 500 mg of sodium iopodate and 1 mg dexamethasone for 4 days in 34 hyperthyroid patients. Surgical indication derived from failure to medical treatment (68%), large goiter (27%) or adverse reaction to PTU (6%). Clinical euthyroidism was achieved after 4 days in all patients. T3 levels decreased from 482 +/- 26.2 to 137.6 +/- 3.7 ng/dl and T4 from 20.6 +/- 1.04 to 15.2 +/- 0.5 micrograms/dl (p < 0.005). Surgery was uneventful in 33 patients, one subject developed supraventricular tachycardia responsive to verapamil. Electron microscopy of the removed thyroid tissue revealed marked decrease of superficial villi and large phagosomes. Thus, sodium iopodate and dexamethasone are effective and safe for preoperative preparation of hyperthyroid patients.

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Pathologic fractures are not commonly described in primary hyperparathyroidism. A 31 year old male with primary hyperparathyroidism developed severe hypercalcemia and cystic osteitis. Bone pains and a fracture of the femur followed. A parathyroid adenoma was demonstrated by ultrasonography. After resection of the tumor, a normalization of serum Ca levels and clinical recovery took place.

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A 13 year old girl presented with a thyroid nodule and enlarged cervical lymph nodes. Symptoms endocrine dysfunction were absent. The patient was submitted to complete thyroidectomy and modified cervical lymph node dissection. Diagnosis of medullary carcinoma was confirmed through both optical and electron microscopy. At 30 months of follow up no evidence of local or distant recurrence was observed.

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