Pediatric urology

Development of the genital and urinary systems is interwoven. Developmental abnormalities may cause problems in both systems, although the presenting problem may be ambiguous genitalia, hypospadias, undescended testis, or a urinary tract infection. The primary care physician must understand the underlying significance of pediatric urologic problems and seek appropriate consultation in a timely manner.     

Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

Biphasic Dose Response in Low Level Light Therapy

The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing cell death and tissue damage has been known for over forty years since the invention of lasers. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial in mainstream medicine. The biochemical mechanisms underlying the positive effects are incompletely understood, and the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. A biphasic dose response has been frequently observed where low levels of light have a much better effect on stimulating and repairing tissues than higher levels of light. The so-called Arndt-Schulz curve is frequently used to describe this biphasic dose response. This review will cover the molecular and cellular mechanisms in LLLT, and describe some of our recent results in vitro and in vivo that provide scientific explanations for this biphasic dose response.     

Paediatric dacryocystorhinostomy

Of 258 cases of dacryocystorhinostomy performed on children in the period September 1981 to September 1991, 130 were for simple, unresolved congenital nasolacrimal duct obstruction. Other indications for surgery included punctal agenesis, lacrimal fistula, post-traumatic and post-inflammatory canalicular obstruction. Of 177 children without canalicular pathology, 171 (96%) were relieved of symptoms with one operation, without canalicular intubation. Of 81 cases with canalicular disease, 55 of 70 (79%) who underwent DCR plus canalicular intubation, and 10 of 11 who underwent DCR plus Lester-Jones tube, were substantially improved with one operation. No child required peroperative or postoperative blood transfusion. Dacryocystorhinostomy in childhood, in experienced surgical hands, is a safe procedure, achieving relief of symptoms in most cases, particularly in the absence of canalicular disease.     

Developmental regulation of 5-HT2 and 5-HT1c mRNA and receptor levels

We investigated the regulation of 5-HT2 and 5-HT1c receptors and their corresponding mRNAs during rat brain development. This study showed that 5-HT2 and 5-HT1c receptors increased markedly during ontogeny. 5-HT2 receptors, measured with [3H]ketanserin or [125I]lysergic acid diethylamide binding, increased 8-fold between embryonic day 17 (E17) and postnatal day 13 (P13). 5-HT2 receptor mRNA levels, quantified by probing Northern blots of total RNA with a synthetic oligonucleotide cDNA probe, multiplied 13-fold between E17 and P5. The developmental pattern of 5-HT2 receptor and mRNA expression appeared to correlate with the serotonergic hyperinnervation of the cortex which occurs between P2 and P17. 5-HT1c receptors, measured with [125I]lysergic acid diethylamide under site-specific conditions, increased 2-fold between E17 and P27, 5-HT1c mRNA increased 5-fold between E17 and P27. Interestingly, the developmentally induced variations in 5-HT1c receptors did not precisely correlate with mRNA alterations. Further study of the factors responsible for these alterations could help to explain the molecular and biochemical mechanisms responsible for modulating receptor levels in vivo.