Vasorelaxation and hyperpolarisation of rat small mesenteric artery by the quaternary anion tetraphenylboron

This study characterises the vasorelaxation and hyperpolarisation effects of the negatively charged quaternary compound tetraphenylboron (TPB) in the rat small mesenteric artery. Segments of rat small mesenteric artery were mounted in a myograph and vessel tone and membrane potential were measured simultaneously. In vessels pre-contracted with vasopressin (0.3–0.6 nM), U46619 (30–90 nM) or methoxamine (0.3–3 M), TPB (0.1–100 M) produced a marked endothelium-independent relaxation. However, vasorelaxation responses to TPB were abolished in tissues pre-contracted with K⁺ (50 mM), and significantly inhibited by glibenclamide (glib, 10 M).In the absence of tone, TPB (1–30 M) caused a concentration-dependent membrane hyperpolarisation of rat mesenteric artery smooth muscle cells, which was not dependent on the endothelium, but sensitive to glibenclamide (10 M). In methoxamine (0.3–3 M) pre-contracted vessels, the relaxation response was associated with a marked hyperpolarisation, which was also sensitive to glibenclamide (10 M), further inhibited by a combination of K⁺ channel blockers (glib [10 M], charybdotoxin [100 nM], apamin [100 nM], 4-aminopyridine [1 mM] and Ba²⁺ [30 M]) and abolished by 50 mM K⁺.The results of this study show that TPB causes a vasorelaxation and hyperpolarisation response in the rat small mesenteric artery through a direct action on the vascular smooth muscle. TPB exerts its effects partially via the activation of K_ATP channels, but also by another mechanism involving K⁺-dependent hyperpolarisation.Abbreviations 4-AP 4-Aminopyridine - ACh Acetylcholine - ChTX Charybdotoxin - Glib Glibenclamide - ODQ 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one - TPB Tetraphenylboron - TPP Tetraphenylphosphonium - U46619 9,11-Dideoxy-9,11-epoxymethanoprostaglandinF₂     

Clinical medicine and the quest for certainty

Orthodox medicine works in a scientific framework which often discounts knowledge arising outside biomedical models and the statistical means by which these are tested. Alternative medicine cannot meet these standards because it is holistic and individual in its orientations toward the understanding and treatment of human illness. But in fact the dominant model also has problems with surgery and other areas such as family practice as sub-disciplines where individualised caring solutions are important. These prominently include areas in which wider social and economic concerns directly impinge on health care so that we need a more liberal attitude to medical knowledge and discovery. I suggest that this wider conception is more in keeping with the Hippocratic ethos as a whole and with the idea of a healing praxis. Because our aim as doctors and health care professionals is to help people, and our knowledge is directed towards furthering this end, medicine is a practical science not able to stand apart and build theories in detached contemplation from within the ivory tower of the academy. However the practicality of medicine and the assurance needed to poison people or inflict grievous bodily harm in an effort to help them often puts a premium on certainties in our thinking about clinical medicine before the scientific basis for such certainty has been established. Therefore, hand in hand with the professional calling that is health care, goes the need for a certain style of belief in what one is doing and its ultimate rightness. This leads to an almost unique profile for medicine among the sciences.     

Surveys of plasma vitellogenin and intersex in male flounder (Platichthys flesus) as measures of endocrine disruption by estrogenic contamination in United Kingdom estuaries: temporal trends, 1996 to 2001

Plasma vitellogenin (VTG) concentrations and the presence of the ovo-testis (intersex) condition have been recorded in male flounder (Platichthys flesus) captured from several United Kingdom (UK) estuaries since 1996 as part of the endocrine disruption in the Marine Environment (EDMAR) project and earlier programs. It has been confirmed that plasma VTG concentrations in male flounder have remained elevated in several UK estuaries (e.g., Tees, Mersey, and Tyne) throughout the period covered by this study. However, the time-series data indicate that plasma VTG, a measure of environmental estrogen contamination, has decreased in fish captured from several estuaries, especially those of the Tyne and Mersey. Shorter time-series data sets from the Forth and Clyde estuaries also suggest a decrease in estrogen contamination at these sites. Trends associated with specific point sources of estrogenic contamination show site-specific patterns. For instance, plasma VTG levels in male flounder captured near the Howdon sewage treatment outfall (Tyne) have shown a steady decline to near baseline levels in 2001, while the plasma of male fish captured at a site adjacent to the Dabholm Gut discharge in the Tees estuary have shown little evidence of a sustained decline. The occurrence of the intersex condition was detected at a low but consistent prevalence through the study period, with the majority of cases recorded in fish captured from the Tyne and Mersey estuaries. The data set does not allow conclusions to be drawn about any temporal trends associated with this condition. The significance of the findings and possible mitigating influences are discussed in terms of the impacts on wild fish and the role of effluent treatment in reducing these.     

Assessing tumor-related signs and symptoms to support cancer drug approval

Cancer causes premature death and significant, often devastating, symptoms. While prolongation of survival is an obvious end point for new cancer drug approval, the US Food and Drug Administration (FDA) has also utilized end points that evaluate patient symptoms. In this article we discuss the end points, evidence, and analyses supporting cancer drug approvals based on evaluations of tumor-related signs and symptoms. With advice from the Oncologic Drug Advisory Committee (ODAC) in the late 1970s and early 1980s, FDA determined that acceptable end points for cancer drug approval were survival or an improvement in the quality of a patient's life, e.g., an improvement in tumor-related symptoms. This article summarizes 15 FDA cancer drug approvals based on patient symptom assessments and/or physical signs (thought to represent symptomatic improvement) as the primary evidence of effectiveness. These include painful bone events (three cases), cosmetic improvement in Kaposi's sarcoma and cutaneous T-cell lymphoma (six cases), the consequences (decreased transfusions, etc.) of long-duration responses in leukemias and lymphomas (two cases), relief of pulmonary or esophageal obstruction (two cases), and one case each of symptom benefit in pancreatic cancer (also associated with survival benefit) and pulmonary symptom benefit in lung cancer. An instructive example of an individual patient benefit end point is discussed, though it did not lead to a drug approval (the cisplatin-epinephrine gel application). Improved trial designs and analysis plans may allow greater reliance on morbidity assessments to support future cancer drug approvals. Drug sponsors are encouraged to include symptom assessments in cancer clinical trials and to perform further research to improve symptom-assessment methods. The FDA routinely meets with sponsors at End of Phase 2 Meetings to discuss drug development plans and the design of phase 3 trials. We encourage sponsors to request special protocol assessments (SPA) after meeting with the FDA to get written confirmation of the adequacy of plans for assessing cancer morbidity and quality of life, including protocols, end points, statistical analysis plans, and draft case report forms.     

A phase II trial of gefitinib (Iressa, ZD1839) in stage IV and recurrent renal cell carcinoma.

PURPOSE: The epidermal growth factor receptor (EGFR) is overexpressed in 75 to 90% of renal cell carcinomas and may play a role in tumor initiation and progression. Gefitinib (Iressa, ZD1839) is a potent, selective EGFR-tyrosine kinase inhibitor. This trial was undertaken to assess the efficacy and toxicity of gefitinib in advanced renal cell carcinoma. EXPERIMENTAL DESIGN: Oral gefitinib, 500 mg once daily, was given continuously. A single-dose reduction to 250 mg daily was allowed for toxicity. The primary end point was response rate (defined as complete remission + partial remission + stable disease). Secondary end points were progression-free survival, overall survival, toxicity, and correlation of response with EGFR status. RESULTS: Twenty-one patients were enrolled on this study, and all are evaluable for response and toxicity. Patient characteristics were median age 61 (range, 35-78 years); 17 males, 4 females; median performance status 0 (range 0-2); median number of prior systemic therapies 1 (range, 0-3). The median and mean number of cycles of therapy received was 3 and 4.7 (range, 1-14+). The best response was stable disease in eight patients (38%). Median progression-free survival was 2.7 months. Median overall survival was 8.3 months. The difference in overall survival was significantly different between patients with progressive disease versus stable disease (6.1 months versus 16+ months; Log-Rank test P value < 0.0001). Three patients required a dose reduction, all for grade 3 diarrhea. There was no apparent correlation between EGFR status and stability of disease or progression of disease. CONCLUSIONS: Gefitinib is without significant conventional activity in renal cell carcinoma. The relation of "stable disease" to treatment or to disease-related prognostic heterogeneity remains to be defined.     

A large planum sphenoidale meningioma with sinonasal extension in a child. Case report and review of the literature

Anterior cranial base meningiomas are rare tumors in children. Due to the extensive involvement of orbit, paranasal sinuses, midface, and anterior skull base, a multidisciplinary approach is warranted. We present a case of a child with a large planum sphenoidale meningioma extending into subfrontal region, ethmoid and maxillary sinuses inferiorly, and orbits laterally. The patient, a 4-year-old girl, presented with long-standing nasal stuffiness and swelling of the midface. An extended frontobasal approach through a bifrontal craniotomy was used to resect the intracranial portion of this mass. The tumor had eroded through nasal septum, medial orbital walls, and left maxilla, structures which were not readily accessible from a cranial approach alone. A modified Weber-Ferguson incision was used for a transfacial approach to resect the residual mass below the skull base. The advantages of combining the bifrontal craniotomy with a transfacial split provided the added exposure to maximize the extent of resection.     

Matrix metalloproteinases and endometriosis

Retrograde menstruation represents a plausible explanation for the development of most cases of endometriosis; nevertheless, additional factors must contribute to the development of disease in only 10 to 20% of women. The discriminating factor(s) in determining the development of active endometriosis probably involves a complex array of potentially interactive influences including steroid exposure, immunological disturbances, genetic predisposition, and, perhaps, environmental toxin exposure. Matrix metalloproteinases (MMPs), enzymes that mediate normal tissue turnover including endometrial breakdown at menstruation, appear to be involved in the invasive establishment of the disease. In addition, several MMPs appear to be inappropriately expressed in the endometrium of women with this disease in association with a reduced sensitivity to progesterone. Altered regulation of endometrial MMP expression in response to steroids may represent a mechanism linking the invasive potential of refluxed endometrium to the establishment of this disease only in certain women.