Inaccuracy of glomerular filtration rate estimation from height/plasma creatinine ratio.

Use of a height/plasma creatinine formula to estimate glomerular filtration rate (GFR) is simpler and less invasive than renal or plasma clearance methods. The aim of this study was to determine whether these formulas enabled accurate prediction of GFR measured from the plasma clearance of 51Cr labelled ethylenediaminetetra-acetic acid (51Cr-EDTA). Thirty nine patients underwent GFR measurement at least six months after potentially nephrotoxic chemotherapy. Altman-Bland analysis was performed on the measured GFR and that estimated simultaneously using the original and a modified Counahan-Barratt formula and the Schwartz formula. The limits of agreement of the estimated GFR with the measured GFR were unacceptably wide in each case, despite highly significant correlation coefficients. The bias was smallest for the modified Counahan-Barratt formula. Use of these formulas to estimate GFR in children is insufficiently accurate for research purposes and has limitations in clinical practice. Furthermore, use of correlation coefficients to evaluate different methods of measuring GFR is inappropriate.     

HIV-1tat induced apoptosis of T-cells is not mediated by TGF-β

Recent reports have demonstrated that the HIV-1 transactivator protein,tat, induces apoptosis in T-lymphocyte cell lines, as well as in peripheral blood mononuclear cells, and stimulates a cascade of events resulting in up-regulation of the potent immunosuppressive cytokine, transforming growth factor-β (TGF-β). In this study we evaluated the ability of TGF-β to mediatetat induced apoptosis in T-lymphocyte cell lines. T-cells treated exogenously with either TGF-β1 or a combination of tat and pan-specific TGF-β neutralizing antibodies showed little change in the amount of apoptosis. When treated with pan-specific TGF-β neutralizing antibodies, Jurkat cells that stably expresstat protein (Jurkat-tat) showed only a modest decrease in apoptosis, while CEM-TART cells (CEM T-cells expressing both HIV-1tat andrev) demonstrated little change in the amount of apoptosis. In conclusion, we have demonstrated that TGF-β does not play a significant role in mediatingtat induced T-cell apoptosis.     

Magnetic resonance angiographic assessment after extracranial-intracranial bypass surgery.

Extracranial-intracranial (EC-IC) bypass operation may be performed to augment the distal cerebral circulation. The bypass patency is usually assessed postoperatively with conventional cerebral angiography. Six patients are reported in whom the bypass patency was assessed using magnetic resonance angiography (MRA): Two had intracavernous carotid aneurysms, three had base of skull tumours encompassing the internal carotid artery, and one had occlusion of the right internal carotid artery with poor collateral reserve as confirmed by an acetazolamide stimulation test. Postoperative conventional cerebral angiography was also obtained in three patients for comparison. The MRA correlated reasonably well with conventional cerebral angiography in showing bypass patency, although conventional cerebral angiography was superior in demonstrating small vessels; MRA has the added advantage of showing the relative flow contribution and flow direction under physiological conditions by using targeted presaturation pulses.     

The growth of cartilage from a free perichondrial graft in the larynx

An attempt was made to promote the growth of new cartilage from a frlage. Three dogs had the perichondrial grafting alone, while two had both the perichondrial grafting and a full thickness buccal mucosal graft. In all these dogs new cartilage was found as early as four weeks postoperative.     

Spontaneous rosette formation and rosette inhibition assays in patients with squamous cell carcinoma of the head and neck.

Peripheral blood lymphocytes from patients with squamous cell carcinoma (SCC) of the head and neck were studied by spontaneous lymphocyte rosette and rosette inhibition (RI) assays prior to treatment. The patients were clinically staged and the results of the assays compared with the clinical stage of the disease. The percentage of T-lymphocytes as determined by the spontaneous lymphocyte rosette test was significantly lower (p less than .01) for the patient group when compared with a normal population. Patients with stage I and II disease did not differ significantly from controls. Individuals with stage III or IV disease, however, had significantly lower T-lymphocyte counts. The tumors were histologically graded as well, moderately well, or poorly differentiated SCC. Patients with poorly differentiated neoplasms had significantly lower T-cell counts. The RI assay (using horse anti-human thymocyte globulin to inhibit rosette formation) was abnormal in many of the patients but did not appear to be a more sensitive in vitro measure of cell mediated immunity in these patients. Performing both tests detected more patients with cellular immunologic incompetence than either one alone.     

The role of naloxone infusions in the treatment of overdoses of long half-life narcotic agonists: application to nor-methadone

This report describes the use of a naloxone infusion at a rate of 300 micrograms/h to provide constant antagonism of the respiratory depressant effects of a near fatal nor-methadone dose in a 2 year old boy. The terminal half-life for nor-methadone was calculated to be 13.5 h. The results indicate that a single dose of a narcotic antagonist with a short half-life (e.g. naloxone) will probably be inadequate to provide long lasting reversal of the effects of overdoses of long half-life narcotic agonists, and that continuous infusion may be the preferable to repeated bolus doses.     

Does antenatal pelvic dilation predict renal scarring?

Moderate antenatal renal pelvic dilation (5-15 mm) may suggest vesicoureteric reflux, but it is not known to predict renal scarring. Dimercaptosuccinic acid scans on such children aged over 4 years showed a scarring rate (0/133 boys, 1/56 girls) similar to our local population. Investigation and treatment of moderate dilation may not be required.