RESUMEN

The fabrication of nanowires with well-controlled lengths and diameters is the basis of the application of one-dimensional nanostructures in more sophisticated electronic and biomolecular device systems. A wide variety of materials, including metals and conducting polymers, have been utilized in nanowire arrays as building blocks for chemical or biomolecular sensors. Thus far, the cheapest and most effective way of nanowire synthesis is electrochemical deposition. In this work, we investigate a new method of electrochemical deposition using two-dimensional electric fields instead of the conventional one-directional electric field between working electrodes. Reproducible fabrication of metallic (palladium) and conducting polymer (polypyrrole) single nanowires with diameters down to 30-50 nm is achieved by application of a vertical gate electric field in addition to the lateral one between the two working electrodes. Diameters and lengths of the nanowires can be easily controlled by varying the dimensions of the nanochannels in which the nanowires are grown. A good ohmic contact between the nanowire and gold electrodes is also obtained, indicating the feasibility of electronic devices based on the single nanowires synthesized via this method. In conjunction with experimental findings of nanowire growth mechanism under two-dimensional electric field, molecular dynamic simulations are employed to further understand the deposition process. This improved electrochemical deposition is applicable for controlled and simple fabrication of a wide range of metallic and conducting polymeric nanowires with small diameters.

Asunto(s)

RESUMEN

We report two patients who had successful combined coronary artery bypass grafting and excision of phaeochromocytoma. These cases represent the first reports of combined coronary artery bypass grafting and laparoscopic adrenalectomy for phaeochromocytoma and of combined coronary artery bypass grafting and excision of extra-adrenal phaeochromocytoma. With careful peri- and intra-operative management, especially in regard to haemostasis, combined operations for coronary artery disease and phaeochromocytoma are both feasible and safe.

Asunto(s)

RESUMEN

Phosducin was evaluated as a candidate gene for the recessive retinal degeneration in the Abyssinan cat, rdAc, using reverse transcription and polymerase chain amplification. The nucleotide sequence of the cat phosducin coding region was determined except for 23 bp at the 5' end. Single-strand conformation analysis of a silent polymorphism within the coding region established the nonlinkage of the phosducin gene with the rdAc locus.

Asunto(s)

RESUMEN

A partially oxidized serotonin (5-HT) was synthesized electrochemically from 5-HT in an acidic solution. This compound was characterized by its chromatographic and electrochemical properties and identified by mass spectroscopy and NMR as tryptamine-4,5-dione (4,5-DKT). In in vitro superfusion experiments, 10(-5)M 4,5-DKT significantly increased the basal 5-HT efflux from both rat hippocampal and striatal fragments. In contrast, 10(-5) M 4,5-DKT did not change the release of dopamine or its metabolite, 3,4-dihydroxyphenylacetic acid from striatal fragments. Continuous perfusion of 4,5-DKT did not modify the effect of KCl on either 5-HT or dopamine release from both brain areas. In in vitro incubation experiments, 10(-8) to 10(-5) M 4,5-DKT evoked 5-HT efflux from rat hippocampus in a dose-dependent fashion. When 10(-4) and 10(-5) M fluoxetine was incubated with 10(-6) M 4,5-DKT, it partially blocked 4,5-DKT-induced 5-HT release. Pargyline, at 10(-5) M inhibited significantly the 5-hydroxyin-doleacetic acid efflux, but did not modify the 4,5-DKT-stimulated 5-HT release. Incubation of 4,5-DKT with glutathione (GSH) and mercaptoethanol indicated that 4,5-DKT binds to sulfhydryl groups. An evidence of GSH-4,5-DKT conjugate was also observed after incubation of 4,5-DKT with a brain homogenate. The interaction of 4,5-DKT with GSH or mercaptoethanol was blocked effectively with N-ethylmaleimide. It is possible that sulfhydryl groups are involved in the mechanism of 4,5-DKT action on 5-HT release.

Asunto(s)

RESUMEN

Forty-five women with known histories of ovarian cancer underwent reoperative surgery. Thirty-seven patients underwent routine second-look laparotomy and eight patients were reexplored with clinical evidence of disease with the intent of re-resection. Preoperative CA 125 levels were obtained. Evaluation as to the predictive value of the CA 125 level and operative findings show a positive predictive value of 100% and a negative predictive value of 54%. Twenty of the forty-five patients had gross disease present on reoperation. Twenty patients were found to have persistent disease at reoperation. Twenty-five percent of patients with CA 125 levels less than or equal to 35 U/ml and 37% of these with CA 125 levels greater than 35 U/ml were resectable to no gross disease at the completion of the reoperation. CA 125 levels greater than or less than 35 U/ml were not predictive of the potential for re-resectability of the tumor.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Currently, there is lack of a histologic classification of squamous cell carcinoma of the cervix that correlates significantly with patient survival. This study investigated the survival predictive value of two immunohistochemical markers, the blood group A,B,H isoantigens and the Oxford Ca antigen, on conventional histologic sections of tumor tissues from 85 surgically treated patients with Stage IB squamous cell cervical cancer. The results indicated that the two antigens are two distinct markers, neither of which correlates with tumor grade. The expression of the A,B,H isoantigens is significantly related to patient survival after adjustment for the depth of stromal invasion of the tumor, whereas the Oxford Ca antigen has no survival predictive value.

Asunto(s)

RESUMEN

A new radioimmunoassay system was established with a monoclonal antibody (1E5) that distinguishes the free beta-subunit of human chorionic gonadotropin in the presence of intact human chorionic gonadotropin, showing only 0.23% cross-reactivity with the intact human chorionic gonadotropin molecule and virtually no cross-reactivity with other glycoprotein hormones or their beta-subunits. Serum samples, taken at initial diagnosis from nine patients with hydatidiform mole and spontaneous remission and 12 patients with subsequent progression to persistent trophoblastic disease, were assayed for free and total levels of the beta-subunit of human chorionic gonadotropin. The assay results were expressed as a ratio of nanograms of free beta-subunit per 1000 mIU of total beta-subunit. Eight of nine patients with mole and spontaneous remission had a ratio value less than 4 whereas 10 of 12 patients with subsequent persistent disease had a ratio value greater than 4. Statistical analysis with chi 2 showed a highly significant correlation of high ratios with eventual progressive disease (p = 0.0009). This study suggests that excessive production of the free beta-subunit of human chorionic gonadotropin may identify patients with a high likelihood of developing persistent trophoblastic disease.

Asunto(s)

RESUMEN

Accurate assessment of lymph node metastasis in cervical cancer is imperative to treatment plan. A histologic sampling method is suggested in which surgically excised lymph nodes are dissected at multiple levels before paraffin embedding. This approach proves to be a more sensitive procedure than the current bisection method in detecting metastasis.

Asunto(s)

RESUMEN

This study was designed to determine whether immunohistochemical stains for tumour-associated markers may be useful in the detection and differential diagnosis of premalignant and malignant lesions of the cervix. The expression of four markers detected by monoclonal antibodies, human milk fat globule 1 and 2 (HMFG-1 and 2), Ca1 and anti-carcinoembryonic antigen (anti-CEA) on conventional histological sections of various cervical lesions has been investigated. None of these markers was specific for neoplastic lesions of the cervix and all four markers were expressed by metaplastic as well as neoplastic cells, and it was concluded that their application in the histopathological examination of the cervix is limited.

Asunto(s)

Asunto(s)

Asunto(s)