Peroxone activated persulfate oxidation of 1,4-Dioxane under column scale conditions.

The research presented herein investigates a peroxone activated persulfate (PAP) oxidant, commercialized under the trade name OxyZone®, and its effects on 1,4-Dioxane (dioxane) contaminated water under column scale conditions in the presence of porous material. There is a limited understanding of the underlying processes that govern PAP oxidation, including the oxidation rates in the presence of aquifer material, and how these reactions proceed once the oxidant is injected into a contaminant plume. Initial batch experiments with porous material (e.g. sand) provided data on the reaction rates of dioxane oxidation as a function of the oxidant: contaminant ratio. The observed degradation rates were approximately 4 times lower than those reported for aqueous solutions containing no porous media. Subsequent column experiments simulated two PAP injections schemes along the flowpath of a dioxane plume to study if the injection of one oxidant slug may yield different results than injecting the same oxidant volume at two separate locations. The injection of one oxidant slug was found more effective, resulting in near complete destruction of dioxane over a prolonged time at a rate more than an order of magnitude greater than in the two-slug injection scenario. Tracer test results suggest that the prolonged oxidant reactivity was in part caused by the high density of the injected oxidant solution. Overall, the results underline the importance of accounting for the properties of both the oxidant solution and the porous material when considering the injection of PAP oxidant into an impacted aquifer.

Ultrasound imaging in the preoperative estimation of the size of tracheostomy tube required in specialised operations in children.

BACKGROUND: Some children are dependent on a tracheostomy for many years. As they grow, larger tracheostomy tubes may be required. Although tables of sizes of tracheas exist for different age groups, they are estimations of normal and may not be accurate for atypical cases. Chest radiographs and computed tomograms (CT) have been used experimentally to estimate tracheal sizes, but are not in regular use. METHOD: High-resolution diagnostic ultrasound imaging was used to estimate the internal and external transverse tracheal diameter, and the depth of the trachea from the skin surface. This allowed selection of the correct standard pattern tracheostomy tube, or the construction of a custom-made tube preoperatively. RESULTS: Four children with various abnormalities who were being considered for replacement tracheostomies were scanned. In one, diagnostic ultrasound confirmed that a new larger fenestrated tube could be placed, which subsequently improved vocalisation and respiration. In the other three, the scan showed there was no space to allow a larger tube to be placed. The standard tables were not suitable for any of these patients. CONCLUSION: High-resolution ultrasound has a role in the non-invasive measurement of the size of the tube needed for specialised operations in children.

Electrocochleography and gentamicin therapy for Ménière's disease: a preliminary report.

OBJECTIVE: It is widely held that an enlarged summating potential (SP) relative to the eighth nerve action potential (AP) is a reflection of endolymphatic hydrops. Aminoglycosides are an accepted treatment for incapacitating Ménière's disease and are known to affect both sensory and secretory cells of the inner ear. The intent of this study was to determine whether this effect on secretory cells could be objectively confirmed by virtue of changes in the electrocochleogram (ECoG) of patients receiving gentamicin therapy for Ménière's disease. STUDY DESIGN: This was a prospective longitudinal study of repeated ECoG measures in three groups of subjects. Ménière's patients undergoing gentamicin treatment were compared with two control groups: individuals with stable Ménière's disease and normal-hearing control subjects. SETTING: The study was conducted at a tertiary referral center. PATIENTS: The sample included 21 normal-hearing subjects, 15 patients with stable unilateral Ménière's disease, and 12 with disabling unilateral Ménière's disease. INTERVENTIONS: For patients with disabling Ménière's disease, gentamicin was administered transtympanically. Audiograms, impedance tests, and ECoG were performed twice for all subjects. MAIN OUTCOME MEASURES: The SP and AP amplitudes, AP latency, and SP/AP ratio of the EcoG were measured. RESULTS: A statistically significant reduction in the SP/AP ratio was observed after gentamicin administration (analysis of variance interaction effect: F2 = 5.64; p = 0.0065). CONCLUSIONS: The significant reduction in the SP/AP ratio in the gentamicin-treated Ménière's group supports the hypothesis that gentamicin improves the electrophysiologic function of the cochlea, possibly by reducing the severity of the associated endolymphatic hydrops.

Cholecystokinin-induced protection against gastric injury is independent of endogenous somatostatin.

Cholecystokinin (CCK) prevents macroscopic injury to the stomach from luminal irritants by an unknown mechanism. The present study was undertaken in conscious rats to ascertain what role gastric mucosal blood flow, sensory neurons, and endogenous somatostatin play in CCK-induced gastric protection. Subcutaneous administration of CCK (10-100 micrograms/kg) significantly reduced macroscopic injury to the acid-secreting portion of the stomach caused by 1 ml of orally administered acidified ethanol (150 mM HCl, 50% ethanol) and augmented gastric mucosal blood flow (fluorescent microspheres) in a dose-dependent fashion. However, although the protective response to CCK (100 micrograms/kg) was still present at 2 h, the blood flow response had returned to baseline by 45 min. Ablation of capsaicin-sensitive afferent neurons with capsaicin (125 mg/kg sc) did not negate CCK-induced protection. Pretreatment with exogenous somatostatin (1 pmol-1 nmol/kg sc) failed to prevent the damaging effects of acidified ethanol to gastric mucosa. Immunoneutralization of endogenous somatostatin with somatostatin monoclonal antibody (2 mg ip) did not reverse the protective actions of CCK. Thus the data suggest that although CCK may prepare the gastric mucosa to withstand a damaging insult by augmenting gastric mucosal blood flow, its protective mechanism is independent of intact sensory neurons and endogenous somatostatin.

Auditory brainstem response. A comparison of different interpretation strategies for detection of cerebellopontine angle tumors.

In this retrospective study (111 tumor; 1370 non-tumor patients), the effectiveness of the auditory brainstem response for identifying cerebellopontine angle tumors was studied using different criteria to interpret the test. Individual ABR features were examined. The I-V was best (sensitivity = 82%; specificity = 97%) but present for only 44% of the population; I-III (sensitivity = 50%; specificity = 96%) and III-V (sensitivity = 30%; specificity = 97%) were worst. Ninety-three percent of patients had V and ILDV, with good results (sensitivity = 74% and 81% respectively; specificity = 93% each). Three interpretation strategies were compared: (1) included the latencies of V, ILDV, I-V, III-V and I-III and ILDI-V, (2) excluded III-V and I-III, (3) used I-V and ILDI-V when available; V and ILDV otherwise. When corrected for hearing loss, strategy 3 provided significantly better specificity (91%) than strategy 1 (87%), with no significant difference in sensitivity (92% and 93%, respectively).

Hearing preservation in acoustic neuroma surgery: value of monitoring cochlear nerve action potentials.

This study reviews the hearing results in 80 consecutive patients who underwent complete removal of histologically proven acoustic neuromas by use of the suboccipital approach. Of these, 56 patients had successful monitoring of cochlear compound action potentials; 20 were not monitored because their surgery predated monitoring; and 4 had unsuccessful monitoring. A significant difference was found in hearing preservation rates between the group in whom compound action potential monitoring was performed and those in whom monitoring was either unavailable or failed (p = 0.02). Overall, 38% (30 of 80) had preserved hearing. There were 51 patients in whom the click threshold for the cochlear compound action potential was measured during surgery. Twenty-one patients had a threshold shift of 20 dB or less, 15 (71%) of these retained serviceable hearing (speech reception threshold < or = 50 dB; speech discrimination score > or = 60%). Of 12 patients in whom the threshold shift was 30 to 60 dB, none had serviceable hearing after surgery. The click threshold shift was predictive of a significant postoperative hearing change (p < 0.001).

Duplex ultrasonography of recurrent varicose veins.

Varicose veins are a common clinical finding with a high recurrence rate following treatment with either surgery or sclerotherapy. Patterns of incompetence in 100 limbs with recurrent varicose veins were determined using duplex ultrasonography. Saphenofemoral or recurrent groin tributary incompetence was present in 44 limbs, an incompetent long saphenous remnant in 20, saphenopopliteal incompetence in 28, perforator incompetence in 35 and deep venous incompetence in 22. No significant incompetence was detected in 15 limbs. The findings suggest an important role for deep venous incompetence in recurrent veins and show that a re-exploration of the groin is unnecessary in over half of limbs with recurrent veins.

Identifying hearing loss and hearing handicap among chronic care elderly people.

This research assessed the appropriateness of the 1989 ASHA Draft Guidelines for the Identification of Hearing Impairment/Handicap in Adult/Elderly Persons for an institutionalized population. We tested 104 elderly chronic care residents using a conventional audiometer, an AudioScope3TM screener, and the Hearing Handicap Inventory for the Elderly. Results showed that this population is capable of performing these tests. Screening should be done at 2,000 Hz only. However, the prevalence of hearing loss is so high (69%) that we recommend conventional testing of all institutionalized elderly where feasible.

The effect of hearing loss on ABR interpretation: use of a correction factor.

Patients suspected of retrocochlear disorders often have abnormal ABRs in the presence of high-frequency hearing loss, making clinical decisions difficult. In a retrospective study of the ABR test results of 1539 patients, the false-positive and false-negative rates for ABR are presented as a function of hearing loss at 4000 Hz, both before and after using Selters and Brackmann's correction factor for hearing loss. For patients with more than 50 db HL at 4000 Hz the false-positive and false-negative rates, uncorrected for hearing loss, were 25.0% and 2.9% respectively, and when the correction factor was used were 12.5% and 5.8%. When hearing loss at 4000 Hz was over 90 dB the ABR was abnormal in 75% of nontumor patients. Conclusions are that a correction factor for hearing loss is helpful with reservations, and that ABR is not a useful test when 4000 Hz hearing loss is greater than 90 dB HL and 2000 Hz is greater than 75 dB HL.

Duplex ultrasound mapping of sites of deep to superficial incompetence in primary varicose veins.

Most patients undergoing treatment for primary varicose veins have only a clinical assessment or examination with a continuous wave Doppler. In this study duplex ultrasound was used to determine the site of deep to superficial reflux in 137 limbs of 96 patients presenting with primary varicose veins. The incidence of saphenopopliteal (22%) and perforator (28%) incompetence was higher than that in previous studies based on clinical examination. Only five limbs had deep venous incompetence at the popliteal level and three of these limbs had lipodermatosclerosis or ulceration. The saphenopopliteal junction was either absent or more than 10 cm from the knee joint in 13% of limbs. The information obtained from duplex scanning of patients with primary varicose veins facilitates surgical management and may lead to a lower recurrence rate.

Evaluating the HR function.

HR departments are evaluated more frequently in organizations that have created a human resource mission statement.

Gangliocytic paraganglioma in association with a duodenal diverticulum.

Gangliocytic paraganglioma is an extremely rare benign neurogenic tumor nearly exclusively located in the second portion of the duodenum, also the most common site of duodenal diverticula. A case is reported of a gangliocytic paraganglioma presenting in a 65-yr-old woman with a 1-yr history of postprandial cramping abdominal pain culminating in a single episode of melena leading to laparotomy. The tumor was identified with difficulty by endoscopy following negative barium studies. Histologically, the tumor is composed of carcinoid-like cells admixed with varying numbers of ganglion cells in a substratum of neuroid spindle cells. The epithelioid cells contain argyrophilic cytoplasmic granules confirmed by electron microscopy to be dense core membrane-bound secretory granules. Review of the literature suggests the tumor described is typical both clinically and pathologically of gangliocytic paraganglioma of the duodenum, except for its unprecedented occurrence in association with a duodenal diverticulum.

Cochlear nerve action potentials during cerebellopontine angle surgery: relationship of latency, amplitude, and threshold measurements to hearing.

The cochlear nerve action potential (AP) was monitored during two types of hearing preservation surgery: (1) removal of small cerebellopontine angle tumors and (2) retrolabyrinthine vestibular nerve section. The purpose of this investigation was to study the relationship between changes in intraoperative AP latency, amplitude, and threshold, and changes in audiometric hearing subsequent to surgery. The presence or absence of a cochlear nerve AP toward the end of surgery accurately predicted the presence or absence of postoperative hearing (93%). Regression analyses were performed to explore the relationship between audiometric pre- and postoperative thresholds and intraoperative AP threshold changes. Statistically significant relationships were found for (1) pre-operative audiometric thresholds and initial AP click thresholds (p = 0.0068); (2) final AP click thresholds and postoperative audiometric thresholds (p = 0.0003); (3) AP click (p = 0.0001) and 1 kHz (p = 0.0006) threshold shifts and pre- to postoperative audiometric threshold shifts. No relationship was found between either AP latency or amplitude values and postoperative hearing. Intraoperative threshold measurements can be used as an indicator of hearing change. If amplitude or latency indices are also monitored it may be better to use stimulus levels close to the evoked potential threshold.

Transhepatic balloon dilation of the distal common bile duct and ampulla of Vater for removal of calculi.

In 17 patients with common bile duct calculi, percutaneous transhepatic balloon dilation of the distal common bile duct and the ampulla of Vater (hepaticopancreatic ampulla) was performed. The calculi were pushed into the duodenum with the catheter, and all were removed without significant complications. This method of calculus removal is an effective alternative to surgery or endoscopic sphincterotomy.

Cochlear nerve monitoring during cerebellopontine angle operations.

The authors present their experience with intraoperative monitoring of cochlear nerve action potentials (AP) in 30 adult patients. Operative procedures were acoustic neuroma excision with attempted hearing preservation and selective vestibular neurectomy in patients with incapacitating Meniere's disease and serviceable hearing (SRT less than 50 db, discrimination greater than 60%). Loss of AP is detected rapidly and has been demonstrated after manipulation of the cochlear nerve and after coagulation of small arteries on the tumour capsule. Presence of an AP at the end of the procedure usually correlates with postoperative preservation of hearing. AP monitoring appears to be a reliable means of detecting potentially reversible changes in cochlear nerve function intraoperatively.