THE MOLECULAR CONTROL OF ANGIOGENESIS

Angiogenesis is a key event in a broad range of pathological conditions including both diseases with an enhanced and insufficient angiogensis. Angiogenesis is often intiated with vasodilation accompanied by an increase in vascular permeability. After destabilization of the vessel wall and degradation of the surrounding extracellular matrix, extravasation of plasma proteins provides a provisional scaffold for the migration of endothelial cells. Endothileal cell proliferation and migration themselves are under tight control by a balance of angionenesis inducers and inhibitors. A large number of angiogenic factors work together in a highly coordinated manner to induce endothelial cell outgrowth and the formation of functional vessels. On the other hand, angiostatic factor may play a critical role in the pathogenesis of ischemic diseases and contribute to the temination of physiological angiogenesis. Angiogenesis ends with the recruitment of pericytes and smooth muscle cells, which stabilize the newly formed vessel. The rapid increase in the knowledge about the molecular mechanisms of angiogenesis has led to first treatment trials in diseases with both enhanced and reduced angiogeneis. Although initial results are promising, much more work has to be done to consdier anti-angiogenic or pro-angiogenic approaches as reliable therapeutic tools.     

The DEBR rat: an animal model of human alopecia areata

The Dundee experimental bald rat (DEBR) is reported as a model for human alopecia areata. Parallels with human alopecia areata were observed in relation to the gradual and patchy loss of hair and the penetration of both pelage and vibrissa follicles by mononuclear cells. In particular, the apparent disruption of the follicles within the precortical region of the epidermal component and consequent alterations of normal geometrical relationships between dermal and epidermal components relate directly to similar studies on human alopecia areata. In comparison with other previously described hypotrichotic rodent mutants, the DEBR rat exhibits a unique mechanism of hair loss which may provide important information regarding the pathomechanism of human alopecia areata.     

Iron Metabolism in Haemodialysis Patients: A STUDY OF THE MANAGEMENT OF IRON THERAPY AND OVERLOAD

Some dialysis units replace iron losses in patients on maintenancehaemodialysis treatment (MHDT) with parenteral iron becauseof doubts about adequate intestinal iron absorption. Recentexperiences in Oxford indicate that this can lead to potentiallydangerous iron loading. Sixty-four of 120 MHDT patients hadserum ferritin levels >1000 µg/l and there was a goodcorrelation between these levels and the number of years ondialysis. A retrospective post-mortem study of 22 MHDT patientsshowed significant amounts of iron in liver and spleen and infive cases there was myocardial iron loading. Five MHDT patientswith iron loading were given desferrioxamine intravenously atdialysis. Iron was chelated but with some difficulty. Iron absorption, using ⁵⁹Fe and the total body counter, wasfound to be similar in both the MHDT patients with iron deficiency(mean ± S.E.M.; 42·5 ± 5·8 per cent)and iron deficient subjects without renal disease (45·3± 1·86 per cent). In iron replete MHDT patientsiron absorption (8·1 ± 2·6 per cent) didnot differ significantly from normal controls (14·9 ±1·6 per cent) while it was reduced in iron loaded MHDTpatients (5·4 ± 0·7 per cent). There wasa good correlation between red cell indices and iron storesin MHDT patients and haemoglobin values in 15 iron deficientMHDT patients rose significantly when treated with oral iron. These findings indicate that the control mechanisms which relateiron absorption to body iron stores are intact in patients onMHDT. Oral iron therapy is recommended and can be monitoredusing red cell indices. Prolonged parenteral iron treatmentis unnecessary and potentially dangerous.     

Recipient to Donor Conduction of Atrial Tachycardia Following Orthotopic Heart Transplantation

We report a case of atrial tachycardia in a 60-year-old male 8 years postorthotopic heart transplantation. At electrophysiology study, the clinical rhythm was found to arise from the remnant of the recipient atrium and was successfully terminated by delivery of radiofrequencv energy. Surgical scars formed at the anastomosis of the recipient and donor atrium during the time of orthotopic heart transplantation are thought to electrically isolate the two areas. Although rarely recognized, dysrhythmias originating from the recipient atrial remnant may occur more often than previously thought.     

Randomized Comparison of Multipolar,Duty‐Cycled,Bipolar‐Unipolar Radiofrequency Versus Conventional Catheter Ablation for Treatment of Common Atrial Flutter

Comparison of Radiofrequency Versus Conventional Catheter Ablation. Introduction: Radiofrequency (RF) catheter ablation has been established as an effective and curative treatment for atrial flutter (AFL). Approved methods include a drag‐and‐drop method, as well as a point‐by‐point ablation technique. The aim of this study was to compare the acute efficacy and procedural efficiency of a multipolar linear ablation catheter with simultaneous energy delivery to multiple catheter electrodes against conventional RF for treatment of AFL. Methods: Patients presenting to our department with symptomatic, typical AFL were enrolled consecutively and randomized to conventional RF ablation with an 8‐mm tip catheter (ConvRF) or a duty‐cycled, bipolar‐unipolar RF generator delivering power to a hexapolar tip‐versatile ablation catheter (T‐VAC) group. For both groups, the procedural endpoint was bidirectional cavotricuspid isthmus block. Results: Sixty patients were enrolled, 30 patients each assigned to ConvRF and T‐VAC groups. Total procedure time (40.2 ± 15.8 min vs 60.5 ± 12.7 min), energy delivery time (8.5 ± 3.7 min vs 14.7 ± 5.2 min), radiation dose (14.5 ± 3.5 cGy/cm² vs 31.7 ± 12.1 cGy/cm²), and the minimum number of RF applications needed to achieve block (4.2 ± 2.4 vs 8.9 ± 7.2) were significantly lower in the T‐VAC group. In 7 patients treated with the T‐VAC catheter, bidirectional block was achieved with less than 3 RF applications, versus no patients with conventional RF energy delivery. Conclusion: The treatment of typical AFL using a hexapolar catheter with a multipolar, duty‐cycled, bipolar‐unipolar RF generator offers comparable effectiveness relative to conventional RF while providing improved procedural efficiency. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1109‐1113)     

A portable instrument for quantifying erythema induced by ultraviolet radiation

The design and performance of an instrument for quantifying ultraviolet-induced cutaneous erythema are discussed. If the instrument is used to record an‘erythema index’ at a site on the skin before and after irradiation, the difference between those two readings is essentially related to an increase in vasodilation and is largely independent of the melanin content of the epidermis.