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Biomedical subjects

N Patel

Publications and source records attributed to N Patel.

At least 19 recordsLinked to original sources
PubMed2006

Is there objective evidence that septal surgery improves nasal airflow?

OBJECTIVE: To identify any prospective, controlled trials providing objective evidence of a reduction in nasal airway resistance following nasal septal surgery, and to undertake a meta-analysis of available data. METHODS: A systematic review with meta-analysis of data was undertaken. A systematic review of the literature using a defined search strategy was conducted to identify papers that used objective methods of airway assessment to evaluate the benefit of septal surgery. Accepted techniques for objective airway assessment included acoustic rhinometry, active anterior rhinomanometry and peak nasal inspiratory airflow. Papers were included based on pre-defined criteria, which included standardization of techniques as outlined in the guidelines of the 1984 committee report on the standardization of rhinomanometry. RESULTS: We identified 942 articles, of which 13 were prospective studies evaluating the objective benefit of nasal septal surgery. Only three of these studies conformed to the inclusion criteria. A meta-analysis on these papers was performed using the Mantel-Haenszel method, and this demonstrated an overall reduction in nasal airway resistance following septal surgery for nasal obstruction (p=0.018). CONCLUSIONS: The majority of studies evaluating the objective benefit of septal surgery did not conform to the recommendations of the committee report on the standardization of rhinomanometry. Only three prospective controlled trials, with pooled data from 141 cases, were identified for meta-analysis. The conclusions that can be drawn concerning objective improvement in airway function following nasal septal surgery are therefore limited. More long-term studies, adhering to standardized techniques, are needed to provide more convincing data.

Airway Resistance↗
PubMed2006

TopCount coupled to ultra-performance liquid chromatography for the profiling of radiolabeled drug metabolites in complex biological samples.

The recent commercial availability of small particle packed columns (<2microm) and associated instrumentation capable of withstanding the high pressures of such columns, has lead to an increase in the application of so called ultra-performance liquid chromatography (UPLC). It has recently been shown that the improved efficiency, resolution and peak capacity of these columns, when coupled to mass spectrometry, provides particular benefit for the identification of drug metabolites in complex biological samples. In this work, the ability of TopCount, a microplate scintillation counter, to act as a suitable radiodetection system for ultra-performance liquid chromatography methods is tested. TopCount, has innumerable benefits over more traditional on-line radioactivity flow detection methods, when dealing with the narrow peak widths and small peak volumes associated with the enhanced efficiency of sub-2microm columns. The system is tested for robustness and sensitivity, and then used to undertake successful metabolite profiling of actual samples, and the data compared to traditional HPLC with on-line radioactivity flow detector.

Animals↗
PubMed2006

Quantitative optical coherence tomographic elastography: method for assessing arterial mechanical properties.

Optical coherence tomography elastography represents a potentially attractive new technique for measuring elastic properties of tissues on a micron scale. In this study, the feasibility of optical coherence tomography (OCT) to study the mechanical properties of phantoms and atherosclerotic arterial samples is reported. The elastic modulus of tissue-mimicking phantoms was measured using OCT and correlated with mechanical measurements. The results indicate that elastography based on OCT represents an attractive technique for evaluating the mechanical properties of tissues.

Aorta↗
PubMed2006

Overexpression of the Axl tyrosine kinase receptor in cutaneous SCC-derived cell lines and tumours.

The molecular mechanisms that underlie the development of squamous cell skin cancers (SSC) are poorly understood. We have used oligonucleotide microarrays to compare the differences in cellular gene expression between a series of keratinocyte cell that mimic disease progression with the aim of identifying genes that may potentially contribute towards squamous cell carcinoma (SCC) progression in vivo, and in particular to identify markers that may serve as potential therapeutic targets for SCC treatment. Gene expression differences were corroborated by polymerase chain reaction and Western blotting. We identified Axl, a receptor tyrosine kinase with transforming potential that has also been shown to have a role in cell survival, adhesion and chemotaxis, was upregulated in vitro in SCC-derived cells compared to premalignant cells. Extending the investigation to tumour biopsies showed that the Axl protein was overexpressed in vivo in a series of SCCs.

Biomarkers, Tumor↗
PubMed2006

Comparison of Coapsys annuloplasty and internal reduction mitral annuloplasty in the randomized treatment of functional ischemic mitral regurgitation: impact on the left ventricle.

BACKGROUND: Functional mitral regurgitation is associated with both annular and ventricular distortion. Aggressive reduction annuloplasty for functional mitral regurgitation acts primarily at the annulus, with variable impact on the left ventricle. The Coapsys device externally reshapes the left ventricle to correct functional mitral regurgitation. Left ventricular reshaping was analyzed in a randomized study. METHODS: The RESTOR-MV study randomizes patients with coronary artery disease and functional mitral regurgitation to either reduction annuloplasty and coronary artery bypass grafting (the RA group) or Coapsys annuloplasty and bypass grafting (the CO group). The Coapsys device consists of epicardial pads connected by a cord. It was placed without cardiopulmonary bypass under echocardiographic guidance and sized to reduce annular dimension and improve leaflet coaptation. Internal reduction annuloplasty was performed by device placement. Intraoperative transesophageal echocardiograms were analyzed in 7 patients having reduction annuloplasty and 7 having Coapsys annuloplasty. RESULTS: Baseline mitral regurgitation (0-4 scale) was similar for the RA (3.0 +/- 0.6) and the CO groups (3.0 +/- 0.6). Intraoperative mitral regurgitation was reduced from 2.86 +/- 0.7 to 0.5 +/- 0.7 (P < .01 pre vs post) for the RA group and from 2.64 +/- 0.9 to 05 +/- 0.7 (P < .01 pre vs post) for the CO group. Annular anteroposterior diameter was reduced with both techniques: RA, 3.45 +/- 0.39 to 2.34 +/- 0.37 cm (P < .01 pre vs post); CO, 3.40 +/- 0.27 to 2.85 +/- 0.34 cm (P < .05 pre vs post). Long-axis dimensions were unchanged with both techniques. Short-axis dimensions measured at three levels were significantly reduced only in the CO patients: basal diameter 4.77 +/- 0.58 to 3.58 +/- 0.38 cm (P < .01 pre vs post); mid diameter 4.88 +/- 0.55 to 3.57 +/- 0.43 cm (P < .01 pre vs post); and apical diameter 4.39 +/- 0.46 to 3.38 +/- 0.34 cm (P < .01 pre vs post). CONCLUSIONS: Coapsys and reduction annuloplasty techniques both acutely reduce functional mitral regurgitation and annular dimension. The Coapsys device provided significantly greater left ventricular reshaping than did reduction annuloplasty. Further evaluation will assess the long-term valvular function and ventricular geometric stability associated with both techniques.

Aged↗
PubMed2006

Antidermatophyte activity of medicago extracts and contained saponins and their structure-activity relationships.

Saponin-rich extracts of Medicago sativa L. have been shown to display antifungal activity against a range of common fungibut only a few individual saponins have been tested against dermatophytes. Total saponins were separately obtained from roots and aerial parts of Medicago sativa, M. murex, M. arabica and M. hybrida. Nineteen saponins and three parent triterpenoids, were tested against three dermatophytic fungi Microsporum gypseum, Trichophyton interdigitale and T. tonsurans using mircowell plate serial dilution assay to determine the Minimum Inhibitory Concentration (MIC). Miconazole was used as a positive control. T. tonsurans appeared to be the most sensitive of the dermatophytes to the active compounds. Aglycones showed less antifungal effect than the glycosides, which displayed a range of activities. Monodesmosidic glycosides of medicagenic acid were the most active compounds, especially the 3-O-beta-D-glucopyranoside, which displayed MIC less than 0.09mm against all three fungi, although those of hederagenin and zanhic acid also showed weak activity (MIC 3.3mm against two fungal species). Bidesmosidic saponins had weaker activity than monodesmosidic ones. This corresponds to activity of these and similar compounds against other fungal species but this is the first comprehensive report of activity of Medicago saponins against dermatophytes.

Antifungal Agents↗
PubMed2006

Drusen classification in bilateral drusen and fellow eye of exudative age-related macular degeneration.

AIM: To assess the value of the modified international classification system in screening high-risk patients with bilateral age-related maculopathy (ARM) from those with lower risk characteristics. METHODS: In total, 164 digital images of 106 patients with either bilateral ARM (group A) or the fellow eyes of unilateral exudative age-related macular degeneration (AMD) (Group B) were included. Patients with no signs of ARM in both eyes or those with bilateral late AMD were excluded. The images were randomised and then graded by two masked ophthalmologists based on the modified International Classification of ARM. RESULTS: The interobserver consistency between the two graders was high with a Kappa value of 0.82 (SE 0.34, P<0.0001). There were no significant differences in the distribution of the stages of ARM between the two subgroups. Stage 3 was the most common stage in each group for both graders followed by stage 2a in the bilateral drusen group. Stages 1a, 2a and 2b were equally the next common stage in the fellow eye of chordial neovascularisation group. CONCLUSION: A screening system based on clinical characteristics would be of value in risk prediction in a clinical setting. Type of Drusen alone, as identified by the modified International grading system, may not be reliably predictive in screening for patients who are at high risk of developing choroidal neovascularisation.

Choroidal Neovascularization↗
PubMed2006

Use of simulated intestinal fluids with Caco-2 cells and rat ileum.

In most in vitro studies of oral drug permeability, little attempt is made to reproduce the gastrointestinal lumenal environment. The aim of this study was to evaluate the compatibility of simulated intestinal fluid (SIF) solutions with Caco-2 cell monolayers and Ussing chamber-mounted rat ileum under standard permeability experiment protocols. In preliminary experiments, fasted-state simulated intestinal fluid (FaSSIF) and fed-state simulated intestinal fluid (FeSSIF) solutions based on the dissolution medium formulae of Dressman and co-workers (1998) were modified for compatibility with Caco-2 cells to produce FaS-SIF and FeSSIF "transport" solutions for use with in vitro permeability models. For Caco-2 cells exposed to FaSSIF and FESSIF transport solutions, the transepithelial electrical resistance was maintained for over 4 h and mannitol permeability was equivalent to that in control (Hank's Balanced Salt Solution-treated) cell layers. Scanning electron microscopy revealed that microvilli generally maintained a normal distribution, although some shortening of microvilli and occasional small areas of denudation were observed. For rat ileum in the Ussing chambers, the potential difference (PD) collapsed to zero over 120 min when exposed to the FaSSIF transport solution and an even faster collapse of the PD was observed when the FeSSIF transport solution was used. Electron micrographs revealed erosion of the villi tips and substantial denudation of the microvilli after exposure of ileal tissue to FaSSIF and FeSSIF solutions, and permeability to mannitol was increased by almost two-fold. This study indicated that FaSSIF and FeSSIF transport solutions can be used with Caco-2 monolayers to evaluate drug permeability, but rat ileum in Ussing chambers is adversely affected by these solutions. Metoprolol permeability in Caco-2 experiments was reduced by 33% using the FaSSIF and 75% using the FeSSIF compared to permeability measured using HBSS. This illustrates that using physiological solutions can influence permeability measurements.

Animals↗
PubMed2006

Solar disinfection of poliovirus and Acanthamoeba polyphaga cysts in water - a laboratory study using simulated sunlight.

AIMS: To determine the efficacy of solar disinfection (SODIS) in disinfecting water contaminated with poliovirus and Acanthamoeba polyphaga cysts. METHODS AND RESULTS: Organisms were subjected to a simulated global solar irradiance of 850 Wm(-2) in water temperatures between 25 and 55 degrees C. SODIS at 25 degrees C totally inactivated poliovirus after 6-h exposure (reduction of 4.4 log units). No SODIS-induced reduction in A. polyphaga cyst viability was observed for sample temperatures below 45 degrees C. Total cyst inactivation was only observed after 6-h SODIS exposure at 50 degrees C (3.6 log unit reduction) and after 4 h at 55 degrees C (3.3 log unit reduction). CONCLUSIONS: SODIS is an effective means of disinfecting water contaminated with poliovirus and A. polyphaga cysts, provided water temperatures of 50-55 degrees C are attained in the latter case. SIGNIFICANCE AND IMPACT OF THE STUDY: This research presents the first SODIS inactivation curve for poliovirus and provides further evidence that batch SODIS provides effective protection against waterborne protozoan cysts.

Acanthamoeba↗
PubMed2006

Homicide of children aged 0-4 years, 2003-04: results from the National Violent Death Reporting System.

INTRODUCTION: To better understand, and ultimately prevent, infant/child homicide, it is imperative to more thoroughly elucidate the circumstances and conditions related to such instances. Data were obtained from the US National Violent Death Reporting System (NVDRS) to illuminate circumstances related to homicide among children aged 4 years or less, and to identify demographic groups which may be at increased risk. METHODS: The NVDRS is an active surveillance system that provides comprehensive information on all violent deaths that occur within participating states within the US. Standard statistical tests were conducted to determine homicide rates among children ages 0-4 across states that provided data for both 2003 and 2004 (Alaska, Maryland, Massachusetts, New Jersey, Oregon, South Carolina, and Virginia). These data were further used to investigate infant/child homicides by race, gender, and other relevant circumstances (for example, victim-suspect relationship, weapon type, and location of homicide). A Poisson regression model was fitted to the sample data to investigate the multivariate relationship between the infant/child homicide rate and available demographic information. RESULTS: The 2003 homicide rate for children ages 0-4 was 3.0 per 100,000 population. The 2004 homicide rate was 2.5 per 100,000 population. African Americans were 4.2 times as likely as whites to be victims of homicide. Suspects were commonly parents/caregivers. The vast majority of infant/child homicides occurred in houses or apartments, using weapons that include household objects. CONCLUSION: Homicides of infants and young children are most often committed in the home, by parents/caregivers, using "weapons of opportunity". This suggests that the risk of infant/child homicide is greatest within the primary care giving environment. Moreover, the use of "weapons of opportunity" may be indicative of maladaptive stress responses. Prevention and intervention strategies to reduce infant/child homicide should target the home environment and attend to maladaptive stress responses.

Black or African American↗
PubMed2006

The NHS breast screening programme (pathology) EQA: experience in recent years relating to issues involved in individual performance appraisal.

BACKGROUND: The original role of the National Health Service breast screening programme (pathology) external quality assessment (EQA) scheme was educational; it aimed to raise standards, reinforce use of common terminology, and assess the consistency of pathology reporting of breast disease in the UK. AIMS/METHODS: To examine the performance (scores) of pathologists participating in the scheme in recent years. The scheme has evolved to help identify poor performers, reliant upon setting an acceptable cutpoint. Therefore, the effects of different cutpoint strategies were evaluated and implications discussed. RESULTS/CONCLUSIONS: Pathologists who joined the scheme improved over time, particularly those who did less well initially. There was no obvious association between performance and the number of breast cancer cases reported each year. This is not unexpected because the EQA does not measure expertise, but was established to demonstrate a common level of performance (conformity to consensus) for routine cases, rather than the ability to diagnose unusual/difficult cases. A new method of establishing cutpoints using interquartile ranges is proposed. The findings also suggest that EQA can alter a pathologist's practice: those who leave the scheme (for whatever reason) have, on average, marginally lower scores. Consequently, with the cutpoint methodology currently used (which is common to several EQA schemes) there is the potential for the cutpoint to drift upwards. In future, individuals previously deemed competent could subsequently be erroneously labelled as poor performers. Due consideration should be given to this issue with future development of schemes.

Breast Neoplasms↗
PubMed2006

Factors influencing the use of antitumoral chemotherapy in the South East of England.

Influences on the use of chemotherapy for the treatment of cancer within the South East region of England for patients diagnosed with colorectal, lung, breast and prostate cancer were investigated. The variables investigated as possibly influencing the selection of chemotherapy were the sex of the patients, their age, the year of diagnosis, the cancer site, the cancer stage, the index of multiple deprivation (IMD) and the cancer network of residence. Logistic regression used to adjust the proportion receiving chemotherapy in relation to other variables considered showed significant differences in the proportion of patients receiving chemotherapy between different cancer sites and different networks. There was also a highly significant trend seen in use of chemotherapy over time; the adjusted proportion of patients receiving chemotherapy increasing from 10.6% in 1993 to 24.3% in 2002. Age, stage and cancer site seemed to have the most influence on the use of chemotherapy.

Adolescent↗
PubMed2006

Treatment of pilonidal disease with laser epilation.

Pilonidal disease is a debilitating, chronic disease of the natal cleft. It mainly involves the sacrococcygeal region and the presentation varies from asymptomatic pits to painful draining abscesses. Treatment options vary from observation to wide excision. Unfortunately, surgical treatment often results in recurrence. The etiologic agent remains in question, as does the optimal treatment. Our objective was to assess the efficacy of laser epilation as an adjunctive therapy to surgical excision of the pilonidal sinus. Eighteen men and five women were treated with laser epilation in our office from 2001 to 2004. All patients had experienced recurrent folliculitis and had undergone some form of drainage procedure or prior excision. After surgical excision of the affected area, a Vasculite Plus laser was used for the epilation treatments. Each session involved 9 to 12 treatments and the patients underwent an average of two sessions. All 19 of the patients that remain in follow-up report no recurrence of their folliculitis or need for further surgical procedures. During treatment, six of the men and one of the women experienced a superficial wound dehiscence. All healed with local wound care and continued laser treatments. Laser epilation is an effective adjunctive therapy for the treatment of pilonidal disease. Although not curative in and of itself, the removal of hair allows better healing and decreases the chance of recurrence by removal of a significant etiology of pilonidal disease.

Adolescent↗
PubMed2006

Approach to a case of autonomic peripheral neuropathy.

Autonomic neuropathy is the term used to describe autonomic disturbances resulting from diseases of the peripheral autonomic nervous system. This is a group of disorders in which the small, lightly myelinated and unmyelinated autonomic nerve fibers are selectively targeted. Most often, autonomic neuropathies occur in conjunction with a somatic neuropathy (i.e. with motor weakness and/or sensory loss), but they can occur in isolation. Causes of autonomic neuropathies are immune-mediated, paraneoplastic, infectious, toxic and drug-induced, hereditary, nutritional and idiopathic. Amongst all, diabetes mellitus is the most common cause. Autonomic features, which involve the cardiovascular, gastrointestinal, urogenital, sudomotor, and pupillomotor systems, occur in varying combination in these disorders. Orthostatic hypotension is often the first recognized and most disabling symptom. Noninvasive, well-validated clinical tests of autonomic functions along with a host of laboratory tests are of immense value to diagnose the presence and to demonstrate the distribution of autonomic failure. Treatment aims to treat specific cause of the autonomic neuropathy (if possible) and to control symptoms of autonomic dysfunction. Present review attempts to outline clinical approach to a case of autonomic peripheral neuropathy.

Arrhythmias, Cardiac↗
PubMed2005

Interactions between nanocolloidal particles in polymer solutions: effect of attractive interactions.

We present a density-functional theory study of nanoparticle interactions in a concentrated polymer solution. The polymers are modeled as freely jointed tangent chains; all nonbonded interactions between polymer segments and nanoparticles are described by Lennard-Jones potentials. We test several recently proposed methods of treating attractive interactions within the density-functional theory framework by comparing theoretical results with recent simulation data. We find that the simple van der Waals approach provides the most accurate results for the polymer-mediated potential of mean force between two dilute nanoparticles. We employ this approach to study nanoparticle interactions as a function of nanoparticle-segment interaction strength and polymer solution density and temperature.

Journal Article↗
PubMed2005

Composition-controlled nanocomposites of apatite and collagen incorporating silicon as an osseopromotive agent.

The development of a novel biocomposite of apatite (Ap) and collagen incorporating low-level additions of silicon (Si) as an osseopromotive agent is detailed. Designed to mimic the structural and compositional characteristics of developing bone, this composite is produced via a coprecipitation method, through which the weight percentage of Ap (i.e., the Ap/collagen ratio) can be varied. Coprecipitates produced at Ap contents of 80 wt % (Ap/collagen=4:1), 60 wt % (Ap/collagen=3:2), and 40 wt % (Ap/collagen=2:3) Ap showed markedly different morphologies, ranging from ceramic-like particulates to rope-like macro-fibrils; at all three Ap contents, however, the nanostructural features of the composites remained qualitatively indistinguishable, with equiaxed Ap nanocrystals distributed randomly throughout a matrix of amorphous collagen. Si incorporation was observed to occur preferentially in the collagenous phase-a result with potential impact on local controlled release of Si.

Animals↗
PubMed2005

Influence of different hormonal regimens on endometrial microvascular density and VEGF expression in women suffering from breakthrough bleeding.

BACKGROUND: The aim of this study was to quantify blood vessel density (BVD) and immunoreactive vascular endothelial growth factor (VEGF) levels in endometrial biopsies taken from women suffering breakthrough bleeding (BTB) under different exogenous hormonal regimes. METHODS: Endometrial biopsies from women in Melbourne with BTB were divided into four groups: combined-continuous hormone therapy (HT) (estrogen and progestin taken daily), cyclical HT (daily estrogen with progestin for 14 days each cycle), progestin-only, or no HT. Subjects from Barcelona were using the Mirena intrauterine levonorgestrel-releasing system for contraceptive purposes, with menstrual diaries for classification into four groups (amenorrhea, infrequent, regular and prolonged). Control biopsies from Melbourne were included in the study. Endometrial samples were immunostained for VEGF and blood vessel localization using an antibody to CD34. RESULTS: Results showed that BVD was significantly reduced in the progestin-only treated group compared with the other three treatment groups (P = 0.028). In addition, all four Mirena BTB groups had significantly reduced BVD compared with controls. Considerable heterogeneity was observed in VEGF immunostaining within and between individual samples with no major differences between HT or Mirena. CONCLUSION: These results provide strong evidence that unopposed progestins reduce endometrial BVD and that there is no link between VEGF immunostaining and BVD or BTB.

Adult↗