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R Davis

Publications and source records attributed to R Davis.

At least 19 recordsLinked to original sources
PubMed2006

Hearing threshold assessment post grommet insertion. Is it reliable?

We aimed to investigate whether auditory brainstem response (ABR), assessed immediately after grommet insertion, was an accurate measure of hearing threshold. Ten children were recruited (20 ears). Patients underwent transient evoked otoacoustic emission (TEOAE) and ABR tests before and after grommet insertion under general anaesthetic. A third assessment was conducted at a six-week review, without anaesthetic or sedation. The hearing threshold in dB and the presence of TEOAE were recorded by senior audiologists. The results of each investigation were compared. At review, only 15 ABR and 17 TEOAE tests, of a possible 20, were recorded. Transient evoked otoacoustic emissions were recorded in 30 per cent of ears pre-operatively, 20 per cent of ears post-operatively and 82 per cent of ears at six-week review. The average ABR thresholds were 23.75 dB (range 10-45 dB) pre-operatively, 27.25 (range 15-40 dB) post-operatively and 15 dB (range 5-25 dB) at six-week review. Comparing pre- and post-operative assessment, decreased thresholds were seen in six ears and elevated thresholds in 11. Comparing the six-week review ABR with the post-operative ABR, 13 ears had decreased thresholds, by as much as 20 dB. Thresholds of 35 dB or greater were measured in six ears immediately after grommet insertion (maximum 40 dB). Threshold shifts of 15 dB or greater was observed in seven ears. The intra-subject variation was shown to be significant (p<0.001) when repeated measures analysis of variance was applied. We conclude that there is evidence that ABR can be inaccurate after grommet insertion, overestimating hearing thresholds. We believe that the mechanism by which the error is realised is temporary threshold shift.

Audiometry, Evoked Response↗
PubMed2006

Doppler evaluation of erectile dysfunction - part 1.

Erectile dysfunction (ED) is the consistent inability to achieve and maintain an erection sufficient for satisfactory sexual activity. Erectile dysfunction affects as many as 30 million men in America, with an increasing prevalence with age. Erectile dysfunction is secondary to organic, psychogenic and combined causes. The first part of this review article describes the guidelines for evaluation and treatment plans for men with ED. It also describes the normal sonographic anatomy of the penis, sonographic technique for evaluation of ED and the normal phases of erection.

Adult↗
PubMed2006

Doppler evaluation of erectile dysfunction - part 2.

Doppler evaluation in erectile dysfunction (ED) has a significant role in determining the cause of ED. The advantages of penile Doppler and pharmacologic duplex ultrasonography include objective, minimally invasive evaluation of penile hemodynamics at a relatively low cost. Arteriogenic ED may be secondary to peripheral vascular disease and diabetes, or may be seen in association with coronary artery disease. Various parameters, such as diameter of the cavernosal artery, peak systolic flow velocity, degree of arterial dilatation and acceleration time, have been suggested for the diagnosis of arteriogenic ED, but peak systolic flow velocity is the most accurate indicator of arterial disease. This second part of the review article describes the various causes of ED and the interpretation and evaluation of color flow Doppler examination in ED.

Erectile Dysfunction↗
PubMed2005

Immunity to tetanus is protective against the development of multiple sclerosis.

Following allegations that Hepatitis B vaccination causes or triggers multiple sclerosis (MS), several epidemiological studies have been conducted to evaluate the association between MS and vaccination. In one study conducted in the US, a significant protective effect on the development of MS was observed for tetanus immunization. We reviewed the medical literature and found two additional recent studies, as well as several older studies, which also observed a significant protective effect of tetanus immunization on the development or progression of MS. Furthermore, decreased humoral and cellular immunity to tetanus toxoid has been observed among MS patients. We postulate that naturally acquired or vaccine-induced immunity to tetanus has a protective effect against the development and progression of MS. We also postulate that this link to tetanus is in part responsible for the gender, age, geographic and socio-economic distribution of MS, as well as its pattern among migrants. The biological basis for this protective effect could be an unspecific boost of bystander suppression of auto-immunity as shown for other infections. Our hypothesis can be tested in several ways. The simplest approach would be to compare tetanus exposure and MS occurrence on a population level. Stronger support would come from the re-analysis of previous studies that have information at the individual level on both tetanus exposure, whether induced or natural, and on the development of MS. Laboratory evidence could be sought by testing the effect of tetanus toxoid on experimental allergic encephalomyelitis, the experimental animal model of MS.

Bystander Effect↗
PubMed2005

Implantable FES system for upright mobility and bladder and bowel function for individuals with spinal cord injury.

STUDY DESIGN: Postintervention. OBJECTIVES: To determine the effectiveness of the Praxis multifunctional implantable functional electrical stimulation (FES) system (Neopraxis Pty. Ltd, Lane Cove, NSW, Australia) to provide standing and stepping ability and bladder and bowel management for individuals with motor complete thoracic level spinal cord injuries (SCI). SETTING: Pediatric orthopedic hospital specializing in SCI. SUBJECTS: Three males, ages 17 and 21 years, with motor-complete thoracic level SCI and intact lower motor neurons to the muscles targeted for stimulation. METHODS: Each subject was successfully implanted with the Praxis FES system. All three subjects received electrodes for upright mobility and the first two subjects received additional electrodes for stimulated bladder and bowel management. Following training, subjects were evaluated in their ability to use FES for nine mobility activities. Acute and chronic experiments of the effect of stimulation on bowel and bladder function were also performed. RESULTS: All three subjects could independently stand up from the wheelchair and could walk at least 6 m using a swing through gait pattern. Two subjects were able to independently perform swing through gait for 6 min and one subject was able to independently ascend and descend stairs. Suppression of reflex bladder contractions by neuromodulation (subject 1) and stimulated contractions of the rectum (subject 2) were observed in acute experiments. When stimulation was applied over the course of several weeks, a positive effect on bowel function was measured. Stimulated bladder contractions were not achieved. CONCLUSION: The feasibility of using the Praxis FES system for upright mobility and aiding aspects of bladder and bowel function was demonstrated with three subjects with thoracic level SCI.

Adolescent↗
PubMed2005

Fryns syndrome phenotype caused by chromosome microdeletions at 15q26.2 and 8p23.1.

BACKGROUND: Fryns syndrome (FS) is the commonest autosomal recessive syndrome in which congenital diaphragmatic hernia (CDH) is a cardinal feature. It has been estimated that 10% of patients with CDH have FS. The autosomal recessive inheritance in FS contrasts with the sporadic inheritance for the majority of patients with CDH and renders the correct diagnosis critical for accurate genetic counselling. The cause of FS is unknown. METHODS: We have used array comparative genomic hybridisation (array CGH) to screen patients who have CDH and additional phenotypic anomalies consistent with FS for cryptic chromosome aberrations. RESULTS: We present three probands who were previously diagnosed with FS who had submicroscopic chromosome deletions detected by array CGH after normal karyotyping with G-banded chromosome analysis. Two female infants were found to have microdeletions involving chromosome band 15q26.2 and one male had a deletion of chromosome band 8p23.1. CONCLUSIONS: We conclude that phenotypes similar to FS can be caused by submicroscopic chromosome deletions and that high resolution karyotyping, including array CGH if possible, should be performed prior to the diagnosis of FS to provide an accurate recurrence risk in patients with CDH and physical anomalies consistent with FS.

Abnormalities, Multiple↗
PubMed2004

GermOnline, a cross-species community knowledgebase on germ cell differentiation.

GermOnline provides information and microarray expression data for genes involved in mitosis and meiosis, gamete formation and germ line development across species. The database has been developed, and is being curated and updated, by life scientists in cooperation with bioinformaticists. Information is contributed through an online form using free text, images and the controlled vocabulary developed by the GeneOntology Consortium. Authors provide up to three references in support of their contribution. The database is governed by an international board of scientists to ensure a standardized data format and the highest quality of GermOnline's information content. Release 2.0 provides exclusive access to microarray expression data from Saccharomyces cerevisiae and Rattus norvegicus, as well as curated information on approximately 700 genes from various organisms. The locus report pages include links to external databases that contain relevant annotation, microarray expression and proteome data. Conversely, the Saccharomyces Genome Database (SGD), S.cerevisiae GeneDB and Swiss-Prot link to the budding yeast section of GermOnline from their respective locus pages. GermOnline, a fully operational prototype subject-oriented knowledgebase designed for community annotation and array data visualization, is accessible at http://www.germonline.org. The target audience includes researchers who work on mitotic cell division, meiosis, gametogenesis, germ line development, human reproductive health and comparative genomics.

Animals↗
PubMed2004

Multiphasic helical CT diagnosis of early medullary and papillary necrosis.

PURPOSE: The feasibility of identifying early manifestations of renal papillary necrosis (RPN) and medullary necrosis (RMN) on multiphasic helical CT, leading to prompt treatment for the causative conditions, and its impact on reducing the incidence of late-stage RML and RPN, was investigated. PATIENTS AND METHODS: Sixty-eight patients (35 male, 33 female) aged 19 to 88 years were examined by multiphasic helical CT for complaints of microscopic hematuria (N=49), macroscopic hematuria (N=2), bacteriuria (N=45), pyuria (N=10), fever (N=15), and flank pain (N=27). Preenhancement, arterial corticomedullary, parenchymal, and excretory phase scans generated 1.25 to 7-mm-thick slices. Follow-up CTs were performed at 1 month (N=62) and 3 months (N=58). RESULTS: While the attenuation coefficients of areas suspect for RMN and RPN were similar on preenhancement CT, they differed substantially on the arterial corticomedullary phase (lesions 55 HU mean; normal medulla 120 HU mean) and parenchymal phase (lesions 58 HU mean, normal medulla 210 HU mean). Investigation for predisposing conditions identified diabetes in 18 patients, upper urinary-tract infections in 48, sickle-cell disease or trait in 17, urinary obstruction in 7, and cirrhosis of the liver in 1. On follow-up examinations, enhancement had normalized in 26 compromised areas of 14 patients at 1 month, and 47 areas (23 patients) at 3 months, remained stationary in 28 patients at 1 month and 9 at 3 months, and progressed in 20 at 1 and 26 at 3 months (P<0.001; Fisher's exact test). Patients (N=35) treated for underlying conditions causing ischemia showed reperfusion in 12 cases at 1 month and 20 at 3 months, while of the untreated patients (N=10), none showed reperfusion, and all lesions increased in size. CONCLUSIONS: Multiphasic helical CT is recommended for identification of RMN and RPN at a stage when effective treatment of underlying causative conditions can arrest or reverse the process of devascularization and prevent loss of medullary tissue.

Adult↗
PubMed2004

Multiphasic helical CT criteria for differentiation of recurrent neoplasm and desmoplastic reaction after laparoscopic resection of renal mass lesions.

BACKGROUND AND PURPOSE: Differentiation of recurrent neoplasm and desmoplastic reaction following laparoscopic resection of renal mass lesions poses a problem. The usefulness of multiphasic helical CT-generated criteria based on enhancement and morphologic characteristics was investigated. PATIENTS AND METHODS: The findings in 5 female and 12 male patients aged 29 to 68 years having renal-cell carcinoma (11-38 mm; N = 15) or solitary angiomyolipomas (N = 2) treated by laparoscopic resection (N = 15) or open segmental surgery (N = 2) were analyzed. Multiphasic helical CT was performed in the preenhancement, arterial corticomedullary, parenchymal, and excretory phases generating 2.5- to 7-mm slices. RESULTS: Both recurrent neoplasms showed median postcontrast enhancement of 119 HU in the arterial corticomedullary phase; the median enhancement of desmoplastic masses was 48 HU. In the parenchymal and excretory phase, recurrent neoplasms showed progressive loss of enhancement, whereas desmoplastic lesions sustained enhancement at about the same level. Recurrent neoplasms presented a defined mass with characteristic spiculation, whereas desmoplastic reaction was characterized by an ill-defined mass with spidery projections extending to abutting fat and residual fascial planes. On 2- to 3-month follow-up scans, recurrent neoplasms showed progressive increases in size and desmoplastic reaction a sharp decrease. CONCLUSION: Enhancement of the mass at the operative site on arterial corticomedullary-phase CT to >90 HU strongly suggests recurrent renal-cell carcinoma, while progressive decrease in size on 1- to 3-month follow-up CT suggests a desmoplastic reaction.

Adult↗
PubMed2004

Multiphasic helical computerized tomography for the assessment of microscopic hematuria: a prospective study.

PURPOSE: We evaluated multiphasic helical computed tomography for the detection and characterization of lesions responsible for hematuria not diagnosed on prior urological surveillance studies. MATERIALS AND METHODS: A total of 393 men and 207 women with recurrent microscopic hematuria but negative urological surveillance studies were examined at 4 participating institutions by multiphasic helical computerized tomography, consisting of pre-enhancement, arterial corticomedullary, parenchymal and excretory phase sequences generating 2 to 5 mm slices through the kidney and lower pelvis. RESULTS: The cause of microscopic hematuria was established in 256 of 600 patients with prior negative urological surveillance examinations with 0.91 sensitivity and 0.94 specificity. The diagnosis was correct in all subsequently proven cases of calculous and renal vascular disease. A total of 67 of 70 inflammatory kidney lesions, 24 of 25 renal neoplasms, 15 of 16 bladder neoplasms, 27 of 35 inflammatory bladder conditions and 21 of 23 ureteral lesions were also correctly diagnosed. The diagnosis of renal medullary and papillary necrosis, and neoplastic lesions of the kidney and bladder allowed the early institution of medical therapy or appropriate surgery. CONCLUSIONS: Multiphasic helical computerized tomography diagnosed lesions responsible for microhematuria in 42.6% of 600 patients with negative urological surveillance examinations. This relatively low cost and low co-morbidity examination is advocated for patients with negative urological surveillance examinations or even as a first examination.

Adult↗
PubMed2004

The potential of emergency department injury surveillance data: an illustration using descriptive analysis of data in 0-4 year olds from the Bath injury surveillance system.

OBJECTIVES: To illustrate the potential of injury surveillance data from an emergency department surveillance system. SETTING: Bath clinical area. METHODS: Data for children (0-4 years old) resident in Bath city in UK were recoded and analysed. RESULTS: There were a total of 3144 attendances and 2300 unintentional injuries - equivalent to an attendance rate of 131/1000. There were 91 thermal injuries and 162 poisoning/ingestions. Descriptive information is presented on the circumstances and consequences. CONCLUSION: The majority of unintentional injuries in 0-4 year olds occur in the home, which is a modifiable environment. Detailed information around the circumstances available from the Bath injury surveillance system allows better focus for prevention messages and priority setting.

Accident Prevention↗
PubMed2003

cPSA and fPSA elimination in African-American men.

In all, 22 African-American males undergoing radical prostatectomy for prostate adenocarcinoma had serum drawn for tPSA, cPSA, and total protein concentrations prior to, during, and after operation to determine the respective elimination rates. African-American cPSA was found to fit best a simple first-order exponential elimination kinetic, with a half-life of 44.6 h. fPSA followed a two-compartment elimination with an alpha-phase elimination of 0.50 h and a beta-phase half-life of 4.2 h. Our results suggest higher rates of elimination for both cPSA and fPSA in an African-American male population with respect to Caucasians and may account for differences in PSA values between races.

Adenocarcinoma↗
PubMed2003

Testicular-sparing surgery: a reasonable option in selected patients with testicular lesions.

OBJECTIVE: To describe our experience of inguinal exploration in patients who had a reasonable chance of having a benign testicular lesion. PATIENTS AND METHODS: From 1995 to 2002, 11 patients (mean age 43 years, range 27-63) with testicular masses that were suspected to be benign underwent inguinal exploration. RESULTS: In nine of the 11 patients, frozen-section analysis and the final pathological results were similar, and two underwent inguinal orchidectomy. In seven patients the testicle was spared. Finally, because of an uncertain pathological diagnosis and patient age, two patients underwent orchidectomy. CONCLUSIONS: Inguinal exploration and testicular-sparing surgery are reasonable options in patients with peripheral intratesticular lesions, on the basis of preoperative ultrasonographic characteristics, and if there is a possibility of the mass being benign because of age, race, physical examination and tumour markers.

Adult↗
PubMed2003

Penile epithelioid sarcoma and the case for a histopathological diagnosis in Peyronie's disease.

OBJECTIVES: To devise a set of clinical criteria that would identify which penile abnormality could be malignant and warrant biopsy, between Peyronie's disease (a pathological fibrosis involving the tunica albuginea of the penis) and epithelioid sarcoma (ES) of the penis (a rare malignant condition which can resemble Peyronie's disease in clinical presentation). PATIENTS AND METHODS: The pathology reports and histological slides of men with Peyronie's disease who underwent penile biopsy were reviewed for ES. The medical charts of suspicious cases were then reviewed by a pathologist, unaware of the origin, for consistencies in signs, symptoms and clinical findings. These consistencies were then to be used to develop criteria for biopsy. Thirty-two men underwent penile biopsy from 1992 to 2001. RESULTS: Because there were no actual cases of ES, a specific set of criteria for ES could not be established. A review of previously published cases was then used for comparison with the present patients. CONCLUSIONS: Many of the previously reported cases included signs and symptoms of urethral narrowing or compression, causing lower urinary tract symptoms. In addition, the penile nodule size was reported to progressively enlarge over time. Because of the high prevalence of Peyronie's disease and low prevalence of ES, biopsy of every penile nodule is not judicious. However, signs and symptoms of urethral obstruction, and a progressively growing and persistently painful nodule should suggest a possible malignancy and warrant biopsy.

Adult↗
PubMed2003

Detection of medullary and papillary necrosis at an early stage by multiphasic helical computerized tomography.

PURPOSE: Multiphasic helical computerized tomography (CT) is advocated to identify early manifestations of papillary and medullary necrosis based on decreased enhancement of circumscribed areas in the medullary pyramid. At this stage the devascularizing process can be reversed if causative conditions such as infections or diabetes mellitus are effectively treated. MATERIALS AND METHODS: Multiphasic helical CTs were performed in 31 male and 26 female patients with complaints of microscopic hematuria (41), macroscopic hematuria (2), bacteriuria (39) and pyuria (9). Pre-enhancement, arterial, early corticomedullary, parenchymal and excretory phase helical CTs generated 1.25 to 5 mm. thick slices. Followup examination included multiphasic helical CT at 1 and 3 months, and excretory urography for some patients at 3 months. RESULTS: Bacteriuria was identified as the probable cause of medullary and papillary necrosis in 39 patients, of whom 28 were treated with effective antibiotic therapy, resulting in normalization and re-perfusion of the initial lesion in 16, no change in 5 and progressive disease in 7 at 3-month followup. Of 8 lesions not treated with specific antibiotic therapy 4 progressed and 4 remained unchanged. CONCLUSIONS: Multiphasic helical CT unlike the excretory urogram can identify medullary and papillary necrosis at an early stage when effective treatment of the underlying cause can reverse the process of devascularization and prevent sloughing of medullary tissues.

Adult↗
PubMed2002

Second-generation microstimulator.

The first-generation injectable microstimulator was glass encased with an external tantalum capacitor electrode. This second-generation device uses a hermetically sealed ceramic case with platinum electrodes. Zener diodes protect the electronics from defibrillation shocks and from electrostatic discharge. The capacitor is sealed inside the case so that it cannot be inadvertently damaged by surgical instruments. This microstimulator, referred to as BION, is the main component of a 255-channel wireless stimulating system. BION devices have been implanted in rats for periods of up to 5 months. Results show benign tissue reactions resulting in identical encapsulation around BION and controls. Stimulation threshold levels did not change significantly over time and ranged between 0.81 to 1.35 mA for all the animals at a 60 micros pulse width. All of the tests performed to date indicate that the BION is safe and effective for long-term human implant. We have elected to develop BION applications by seeking collaboration with the research community through our BION Technology Partnership.

Animals↗