The Iodide Space in Rabbit Brain

In the present investigation labeled iodide was used to investigate the interrelationship between brain, blood and cerebrospinal fluid, to examine active transport across the blood-brain- and the blood-cerebrospinal fluid barriers, and to estimate the extracellular space of the brain. The iodide space in the brain and the iodide concentration in cerebrospinal fluid after intravenous administration of radioactive iodide are determined by the following mechanisms. Iodide passes into the cerebrospinal fluid but active transport in the choroid plexus moves most of the iodide back again into the plasma, keeping the concentration at a very law value. An extracellular fluid is formed at the blood-brain barrier possibly in a similar way. The iodide concentration of this fluid is unknown but is probably higher than that in the cerebrospinal fluid. Diffusion of iodide across the brain-cerebrospinal fluid barrier transports this ion from the brain into the cerebrospinal fluid which is constantly renewed "sink action". The iodide space was found to be 2.4% four to five hours after the intravenous administration of 131I, the iodide content of the cerebrospinal fluid was 1.2% of that of the TCA serum filtrate. The iodide space increased to 10.6% in preparations in which in addition to 131I unlabeled iodide (to a serum concentration of 25 to 50 mM) was administered to saturate the active transport processes in the choroid plexuses and blood-brain barrier. The iodide activity of the cerebrospinal fluid in these experiments increased to 29.3% of that in the TCA serum filtrate. In experiments in which the inhibitor of iodide transport, perchlorate (8 mM), was injected intravenously with the 131I-, the iodide space was 8.2% and the iodide concentration in the cerebrospinal fluid 26.4%. These experiments demonstrate the effect of saturation and inhibition of active transport on the iodide space. They show furthermore that the depression of the active transport did not raise the iodide concentration in the cerebrospinal fluid to the plasma concentration. The relatively low (1/3 of that in the serum TCA filtrate) iodide concentration in the cerebrospinal fluid under these circumstances was ascribed to a differential permeability of the blood-cerebrospinal fluid barrier for iodide and chloride. The sink action can be eliminated by perfusion of the ventricles with an artificial cerebrospinal fluid containing iodide. Ventriculocisternal perfusion with 131I- alone resulted in an iodide space of 7.2% after 4.5 hours. An iodide space of 10.2% was determined by a combined intravenous administration and ventricular perfusion with an artificial cerebrospinal fluid containing the same concentration of 131I as present in the plasma. When in similar experiments perchlorate was administered intravenously, the iodide space rose to 16.8%. The iodide space determined by simultaneous intravenous injection and ventricular perfusion with both labeled and unlabeled iodide, in a concentration sufficient to saturate the active transport, was 20.8%. In the latter instances the sink action is eliminated and also active transport is inhibited or saturated. It was postulated that under these conditions the iodide concentration in plasma and brain extracellular fluid are approximately the same. The use of the iodide space as a measure of the brain extracellular space was discussed.</p

DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING RP-HPLC METHOD FOR THE DETERMINATION OF XIPAMIDE IN PURE AND DOSAGE FORMS

Objective: A simple, selective, precise and stability-indicating RP-HPLC-method was developed and validated for the determination of xipamide (XIP).Methods: Stability tests were done through exposure of the analyte solution to thermal, photolytic, hydrolytic and oxidative stress conditions. The chromatographic separation was carried out in less than five min on a RP stainless-steel C-18 analytical column (150 mm ×4.6 mm ID, 5 µm) with an isocratic elution system of 0.023 M orthophosphoric acid of pH 2.6 and acetonitrile as the mobile phase in the ratio of 60: 40 at 1.5 ml/min flow rate at room temperature. A diode array UV was used at 220 nm for detection.Results: The degradation products were well separated from the pure drug. The elution time of XIP was found to be 4.561±0.024 min. The method was validated in terms of linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and robustness. Good linearity was found in the concentration range of 1–100 µg/ml with a correlation coefficient of 0.9999. Intraday and interday precision were within 1.4%. LOD and LOQ were 0.088 μg/ml and 0.267 μg/ml, respectively and percentage recovery of XIP was found to be 99.92±1.02 %. Conclusion: The proposed method was successfully applied to the determination of XIP in pure form and in its pharmaceutical preparation without interference from its degradation products.Keywords: Xipamide, Stability indicating RP-HPLC, Stress degradation, Pure form, Dosage form

Hyperhidrosis in children and review of its current evidence-based management

Hyperhidrosis (HH) is excessive sweating that usually interferes with the patient’s social life. In more than 80% of the cases, the symptoms start in childhood. Early detection and management can significantly improve the patient’s quality of life; however, HH remains widely underdiagnosed and undertreated, particularly among children. Many patients do not realize that they have a treatable condition and reports have shown that only 38% of the patients had discussed their condition with a healthcare  professional. The aim of this article was to improve awareness on the significant sequel of HH in children and highlight its effects on their quality of life and various available treatment options.Keywords: hyperhidrosis, medical treatment, paediatric, sympathectomy, thoracoscop

Using the renal pelvis flap to replace the whole hypoplastic ureter: a preliminary report

Background Hypoplastic ureter is a rare condition usually associated with hypoplastic kidney, and it ends with nephrectomy in most of the cases. Many techniques have been described as ureteric substitutes in the literature. Here, we describe a new technique using the renal pelvis flap to replace the whole hypoplastic ureter in two cases. Objective The aim of this study was to describe a new surgical technique in the management of ureteric hypoplasia.Patients and methods Of the two boys diagnosed antenatally, unilateral hydronephrosis was detected in one boy and a huge renal cyst was present in the other, with evidence of postnatal progressive obstruction necessitating surgical intervention. On exploration, hypoplastic ureter throughout its entire length was an accidental intraoperative finding. The renal pelvis flap was taken and tubularized to replace the entire ureter, and reimplanted into the urinary bladder. This technique was the primary procedure in one case, whereas it was the secondary procedure in the other case after failure of initial trial of pyeloplasty.Results The postoperative period was uneventful with adequate drainage of the renal pelvis in the short-term follow-up (6 and 3 months consecutively).Conclusion The renal pelvis flap is a new feasible alternative procedure for ureteric replacement in a hypoplastic ureter when there is preserved renal parenchyma.Keywords: renal pelvis flap, ureteral hypoplasia, ureteric replacemen