Effects of subsurface heterogeneity on natural bioremediation at a gasoline spill site.

A test cell of 3-m by 6-m located at the mid-point of a gasoline spill site was selected to test the hypothesis that the rate of hydrocarbon biodegradation is influenced by the spatial distribution of the electron acceptors, aqueous geochemistry, and microbial population. Multilevel samplers (MLSs) were installed at four corners of the test cell for groundwater sampling. Sampling ports were placed at 0.3-m intervals from 1.5 to 4.8 m below land surface (bls). A 0.91-m by 12.7-cm sediment core (from 3.3 to 4.2 m bls) in the center of the MLSs was collected. The core was cut into 7 sections, and each was used for sediment extractions, microbial enumeration, grain size distribution, and microcosm studies. Groundwater analytical results indicate that iron reduction was the dominant biodegradation process within this test cell. Iron-reducing process caused the preferential removal of certain compounds. Microbial enumeration results show that the distribution of microbial population varied with depth and sediment materials. Lower microbial population was observed in those sections with higher portion of clayey materials. The less permeable materials would limit the bacterial transport, decrease the bioavailability of Fe(III) to iron-reducing bacteria, and thus cause the low biodegradation activity. Results suggest that using blended sediments for biodegradation rate measurements may provide misleading results.

Irreversible sensorineural hearing loss as a result of azithromycin ototoxicity. A case report.

Azithromycin, an azalide antibiotic, rarely causes ototoxicity. According to the few reports in existence, azithromycin-induced ototoxicity occurred following prolonged high-dose therapy in patients with acquired immunodeficiency syndrome and resulted in a reversible sensorineural hearing loss. We present a case of irreversible sensorineural hearing loss due to azithromycin ototoxicity in an otherwise healthy woman following low-dose exposure to azithromycin.

Intractable benign paroxysmal positional vertigo in patients with Meniere's disease.

OBJECTIVE: To provide a detailed description of the coexistence of benign paroxysmal positional vertigo (BPPV) and Meniere's disease in individuals and to offer a possible mechanism that explains the findings in these patients. STUDY DESIGN: Retrospective. METHODS: Chart review. RESULTS: Of 162 patients diagnosed with Meniere's disease between January 1998 and January 1999, 9 were found to have both "definite" Meniere's disease and "certain" BPPV. Meniere's symptoms preceded the onset of BPPV in all of our patients. Seven of the 9 patients were female. Except for one patient who experienced BPPV bilaterally, BPPV was limited to the same ear as the Meniere's disease. All patients presented with intractable BPPV that did not respond completely to otolith repositioning procedures. A detailed description of five patients is presented. CONCLUSION: Our data, in conjunction with that of others, suggest that Meniere's disease may predispose patients to intractable BPPV. Hydropically induced damage to the maculae of the utricle and saccule or partial obstruction of the membranous labyrinth may be possible mechanisms that explain the coexistence of Meniere's disease and BPPV.

Ethics and practice in organ transplantation in patients infected with human immunodeficiency virus.

In sum, much more needs to be known about the issue of transplantation in HIV-infected patients before the current state of extremely limited access to transplantation for these patients can be medically and ethically justified. Approaches to remedy this situation may include well-designed outcome studies; revision of existing local, regional, and national policies to better reflect the current state of knowledge; and education of clinicians, patients, and the public about this topic. Nurses can effect change in this area as informed clinicians, patients' advocates, researchers, and policy makers.

Effects of cis-platinum chemotherapy on otoacoustic emissions: the development of an objective screening protocol. Third place--Resident Clinical Science Award 1998.

To develop an objective, fast, and simply performed screening protocol for cis -platinum (CP) ototoxicity, we compared the efficacy of screening with distortion-product otoacoustic emissions (DPOAEs) with the outcome of both conventional and ultra-high-frequency (UHF) audiometry. Baseline audiometric and DPOAE testing was performed in 66 patients, 33 of whom met criteria for inclusion in the final database. Comparisons were made between baseline measurements and those recorded before subsequent CP infusions. Outcomes were analyzed clinically and with paired repeated-measures analysis of variance. Results indicated that DPOAEs and UHF were better measures than conventional audiometry. Further, DPOAEs may be better suited for screening older patients receiving CP chemotherapy because DPOAEs are as sensitive as UHF and are present in a greater number of these patients. Screening with DPOAEs may be enhanced by testing only in the 3- to 5.2-kHz range, thus decreasing testing time. Higher time averages to increase the signal-to-noise ratio and use of this narrower bandwidth might also allow for accurate bedside testing.

Adenosine conversion of supraventricular tachycardia associated with high-dose epinephrine therapy for cardiac arrest.

Adenosine has received wide acceptance as the drug of choice for initial treatment of supraventricular tachycardias (SVT), and as a diagnostic adjunct in hemodynamically stable, wide-complex tachycardias. This report describes the successful use of adenosine for the treatment of SVT occurring after successful initial resuscitation from ventricular fibrillation, in which a high dose of the epinephrine protocol was used.

Esophageal replacement with colon in children.

Between 1974 and 1994, 25 colonic interposition procedures were performed for esophageal replacement in 23 cases of esophageal atresia (EA) and 2 corrosive strictures. Nine patients had one-stage and 16 had two-stage reconstructions. The transthoracic route was used in 16 cases (64%) and the retrosternal route in 9 (36%). Average age at the time of operation in EA patients was 17 months (range 12-33), and the children with corrosive injuries were 3 and 6 years old. Mean age at follow-up was 11.8 years (2.3-20.5 years). There was no mortality in the series. One patient developed full-graft necrosis and had a gastric pull-up procedure later. One child had partial graft necrosis (3 cm at the cervical end), however, enough colon was available for reconstruction. Ten patients developed a leak from the cervical anastomosis (40%) and 7 developed a stricture at the cervical esophago-colonic anastomosis (28%). The strictures were treated by repeated esophageal dilatation, and 3 patients required revision of the anastomosis (12%). Other complications included acid reflux in 2 cases (8%), small-intestinal obstruction in 1 (4%), redundancy of the colon in 1 (4%), and chest infections in 2 (8%). Follow-up included assessment of the patient's symptoms, serial growth measurements (height and weight), and where relevant, endoscopy and a contrast swallow or meal. There was a 52% improvement in weight and height percentiles post-operatively. Each of the 19 patients who had barium swallows showed rapid transit and emptying without any significant delay or hold-up. Overall long-term results were excellent in 13 patients (52%), good in 7 (28%), and fair in 5 (20%). The colon conduit thus provides an excellent substitute esophagus in pediatric patients.

Necrotizing external otitis in patients with AIDS.

In a retrospective review of seven patients with AIDS who were diagnosed with necrotizing external otitis between 1990 and 1995, it was found that the presentation of necrotizing external otitis in patients with AIDS differed from the classic description of malignant external otitis in several respects. The patient population was significantly younger and nondiabetic. Granulation tissue was usually absent from the external auditory canal and Pseudomonas aeruginosa was not the predominant pathologic organism. Also, outcome was found to be significantly worse. Thus a high index of suspicion must be entertained and vigorous local and systemic treatment initiated early in the course of disease to achieve a satisfactory outcome.