Semi-synthesis of C20 3H-resiniferatoxin

There has recently been considerable interest concerning the biochemical and pharmacological mechanisms of action of resiniferatoxin (Rx). Rx is a daphnane diterpene ester, which is part of the phorbol ester family of diterpenes. We have synthesized ³H-Rx in a three-step process from the parent alcohol, resiniferonol (Ro). The tritium label is incorporated into the resiniferonol nucleus at the C₂₀ position, before esterification of ³H-Ro to ³H-Rx. This compound will be of use in the elucidation of the binding characteristics of Rx to its biochemical receptor site(s).     

The effect of 2,6-bis(diethanolamino)-4-piperidinopyrimido [5,4-d]-pyrimidine (RA233) on growth,metastases and lung colony formation of B16 melanoma

The dissemination of malignant cells from a primary tumor to distant host sites appears to be influenced by blood platelets of the hemostatic system. Under conditions that did not inhibit primary tumor growth, RA233 decreased both the incidence and frequency of spontaneous lung metastases by 66% and 69%, respectively. Although RA 233 effectively inhibited the formation of spontaneous metastases, oral administration of RA233 prior to and after the intravenous inoculation of 1 × 10⁵ B16F10 murine melanoma cells failed to inhibit subsequent lung colony formation. These findings indicate that RA233 has antimetastatic activity, and that inhibition of platelet aggregation is not the sole determinant of this action.     

An automated method for generating analogic signals that embody the Markov kinetics of model ionic channels

In this work we present an automated method for generating electrical signals which reflect the kinetics of ionic channels that have custom-tailored intermediate sub-states and intermediate reaction constants. The concept of our virtual single-channel waveform generator makes use of two software platforms, one for the numerical generation of single channel traces stemming from a pre-defined model and another for the digital-to-analog conversion of such numerical generated single channel traces. This technique of continuous generation and recording of the activity of a model ionic channel provides an efficient protocol to teach neophytes in the field of single-channel electrophysiology about its major phenomenological facets. Random analogic signals generated by using our technique can be successfully employed in a number of applications, such us: assisted learning of the single-molecule kinetic investigation via electrical recordings, impedance spectroscopy, the evaluation of linear frequency response of neurons and the study of stochastic resonance of ion channels.     

MR arthrography of the knee: how, why, when

MR arthrography combines the techniques of arthrography with MR imaging to benefit from the added imaging information afforded by intra-articular distention. This article reviews technical considerations for MR arthrography, potential complications, indications, pitfalls in imaging diagnosis, and commonly encountered pathology. It is an elegant study that can offer precise diagnostic information in the appropriate clinical setting.     

Bronchoscopic lung volume reduction in patients with severe emphysema: anesthetic management

Bronchoscopic lung volume reduction is a novel approach to the treatment of severe emphysema. Its objective is to achieve the same improvements in lung function and exercise tolerance as lung volume reduction surgery while avoiding the surgical morbidity and mortality. We describe the anesthetic experience in a series of seven patients who underwent a total of eight procedures (one patient underwent a second procedure on the contralateral side). The technique used was one of total IV anesthesia using remifentanil and propofol, with a ventilatory strategy aimed at avoiding gas trapping and dynamic hyperinflation. To achieve this pressure, limited ventilation with a prolonged expiratory phase was provided by a Draeger Evita 2 ventilator. This technique resulted in intraoperative hypercapnia (Paco(2) 6.75 kPa) compared with baseline values (median Paco(2) 5.1 kPa; P < 0.05), but 2 h postoperatively the arterial partial pressure of CO(2) was returning to baseline (median Paco(2) 5.6 kPa; P < 0.01 compared with intraoperative data). There were no deaths or admissions to the intensive care unit after the procedure. One patient developed a pneumothorax that required drainage, three patients had acute exacerbations of chronic obstructive pulmonary disease, and one patient developed a cough that resolved spontaneously. Total hospital stay did not exceed 5 days for any of these patients.     

Horner's syndrome following excision of a vagal paraganglionoma

We report a case of excision of a vagal paraganglionoma resulting in Horner's syndrome. The case was initially misdiagnosed as a carotid body tumour and demonstrates the need for adequate preoperative imaging and patient counselling for likely complications of surgery.