Biomedical subjects
Publications and source records attributed to U Patel.
The modern management of urolithiasis requires a multi-disciplinary approach. Imaging plays a central role in both diagnosis and planning therapy of renal and ureteric calculi. This article reviews the current status of diagnosis and management of stone disease, and the contribution of radiological imaging in accurately triaging a given case to the most appropriate therapy.
The majority of renal and ureteric stones are now managed by minimally invasive techniques, for example nephrostomy, ureteral stents, extracorporeal shockwave lithotripsy or percutaneous nephrolithotomy. A multi-disciplinary approach is necessary, and this review examines the status of modern stone therapy and the contribution of the radiology department.
AIM: The diagnostic contribution of the anteroposterior (AP) view was studied to assess whether this view could be omitted safely, thus reducing the radiation burden received by patients undergoing lumbar spine radiography. MATERIALS AND METHODS: Prospective analysis of 1030 consecutive referrals for lumbar spine radiography from general practice. RESULTS: In the majority of cases (90.5%) the AP view was non-contributory. In 4.2% the diagnosis was strengthened and it was altered in 4.6%. However, in the latter group only 1.3% of the total were considered significant alterations. These were cases of possible, but not definite, pars defects and sacroiliitis. Specific important conditions such as infection, malignancy and benign tumours were not missed on the lateral view alone, in our study population. The radiation burden is reduced by 75% by omitting the AP view. CONCLUSION: A single lateral view is an adequate examination, with the proviso that sacroiliac joint disease is not assessed on this view and some pars defects and facet joint degenerative changes may be overlooked. The radiation protection gains are considerable. A single lateral lumbar view is now our routine practice unless sacroiliitis is a specific clinical concern.
OBJECTIVE: To determine whether low-dose aspirin increases morbidity after transrectal ultrasonography-guided sextant prostate biopsy. PATIENTS AND METHODS: In a single-centre prospective cohort study of 200 patients who underwent sextant prostate biopsies, those routinely taking low-dose aspirin were encouraged to continue to do so before and after biopsy. The morbidity in each case was assessed using a standardized questionnaire that patients completed in the 7 days after biopsy. The presence of haematuria, rectal bleeding and haematospermia were recorded. The questionnaire also directed the patient to record fevers, use of analgesia and any further treatment received. RESULTS: In all, 36 patients took aspirin whilst the other 141 did not. There were no major complications in either group. Of the patients on aspirin, 20 (56%) had haematuria, compared with 83 (59%) of those not taking aspirin (difference 3%, 95% confidence interval, CI, -15 to 21). Overall bleeding (haematuria, rectal bleeding and haematospermia) occurred in 22 patients (61%) of the aspirin group and 105 (74%) of the other group (difference 13%, 95% CI -4 to 31). Comparisons of other morbidities between the groups are also discussed. CONCLUSIONS: There was no statistically significant difference in the incidence of haematuria or overall bleeding after biopsy between the groups. There is no evidence that aspirin needs to be discontinued before sextant prostate biopsy.
The aim of this study was to compare the efficacy of CO(2) angiography with that of iodinated contrast angiography for vascular mapping prior to partial nephrectomy for presumed renal cell carcinoma. 13 consecutive patients were studied and all patients underwent selective renal angiography using both CO(2) and iodinated contrast medium. Digitally subtracted images were acquired and compared. Seven male and six female patients, with a median age of 58 years (range 46-74 years), were examined. On comparing images the main renal artery was visualized in all cases with both contrast agents. The segmental vessels were seen in 7 of 13 CO(2) studies and 12 of 13 iodinated contrast studies. CO(2) was also inferior in the depiction of tumour circulation, showing it in 4 of 13 cases compared with 9 of 13 cases using iodinated contrast. It therefore appears that CO(2) angiography offers no diagnostic advantage and is also inferior to iodinated contrast angiography in the pre-operative vascular mapping of renal tumours.
OBJECTIVE: To compare the technical performance of a 33-mm core-length biopsy needle with that of the standard 18 mm needle, as many prostate cancers are isoechoic and in large prostates the tissue coverage with the 18 mm needle is inadequate. PATIENTS AND METHODS: A 33-mm core length BioPince VSL disposable needle (Amedic, Sweden) and a standard TruCut 18 mm needle (Medical Device Technology Inc., FL, USA) were used to take prostatic biopsies in two groups of 15 patients. The following variables were assessed for each group: mean core length, core quality, capsular coverage (one or both capsules within the specimen), and side-effects in the first week after biopsy (for the BioPince group, surveyed using a self-completed questionnaire). The results were compared with historical data from a group of 30 patients biopsied using the standard needle. RESULTS: For the BioPince and standard groups the mean (sd) core length was 19.4 (8.9) and 14.9 (5.1) mm, respectively. Four needles in the BioPince group failed to capture a sample, requiring needle replacement. The samples were fragmented in 15 of 90 (17%) and 41 of 90 (46%) biopsies in the BioPince and standard groups, respectively (P < 0.05). Specimens had both capsules present in five of 90 (6%) and four of 90 (4%), respectively. Within 7 days minor bleeding was the most common side-effect. Pain after biopsy was the only symptom showing a significant difference between the groups, at six of 15 and none (P = 0.001), respectively. The incidence of haematuria, haematospermia and rectal bleeding was similar in the two groups (P > 0.05), but fever more common (three vs none) in the BioPince group (P = 0.06). CONCLUSION: When set at a 33-mm stroke length, the BioPince needle increases the mean core length by 30%, with less fragmentation than a standard 18 mm needle. However, it has a significant failure rate for capture (27% needle replacement rate), slightly greater morbidity (pain and possibly fever) and shows no advantage in capsular coverage. Therefore, there are shortcomings with this end-cutting needle when used at 33 mm core length.
AIM: To evaluate a formula based on the patient's height for choosing the correct length of ureteric stent and to compare its accuracy with that of direct ureteric length measurement. METHODS: Thirty-five patients (41 ureters) with ureteric obstruction were prospectively studied. All received Percuflex 8F double pigtail ureteric stents. Stent lengths were chosen according to patient height: < 5 ft 10 in (<178 cm) = 22 cm; 5 ft 10 in to 6 ft 4 in (178-193 cm) = 24 cm; > 6 ft 4 in (>193 cm) = 26 cm. The final stent position was graded using a 5-point scale (0 representing ideal length, with -2 and +2 being too short and too long respectively). Stent length acceptability using direct ureteric measurement was then estimated using the same 5-point scale; and the results compared. RESULTS: Patient's height correctly predicted stent length in the majority of ureters (grade 0 = 61%), with no stent being too short. In comparison, direct ureteric measurement oversized the stent in 83%, correctly predicting stent length in only 17%. CONCLUSION: Patient's height is a more reliable guide to ureteric stent length than direct ureteric measurement, particularly in the dilated and tortuous ureter. This may be because the redundant ureter is capable of significant shortening under the influence of the ureteric stent.
Neuroleptic malignant syndrome is a rare (incidence, 0.02%-3.2%) but dangerous complication following the use of neuroleptic drugs. When not promptly recognized, this disease carries a high mortality (10%-20%) and morbidity rate. We report an unusual case of neuroleptic malignant syndrome that presented predominantly with autonomic instability in the form of recurrent episodes of respiratory distress. The respiratory distress was initially caused by pulmonary edema and later was caused by severe bronchorrhea. We propose that aspiration pneumonia resulting in respiratory failure, the leading cause of death in neuroleptic malignant syndrome, may be a result of a combination of altered mental status and bronchorrhea. This has therapeutic implications because early institution of bromocriptine/dantrolene can prevent aspiration pneumonia and, hence, mortality from respiratory failure.
The aim of this article is to review the radiological management of complications following renal transplant.
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Oxazolidinones are potent inhibitors of bacterial protein biosynthesis. Previous studies have demonstrated that this new class of antimicrobial agent blocks translation by inhibiting initiation complex formation, while post-initiation translation by polysomes and poly(U)-dependent translation is not a target for these compounds. We found that oxazolidinones inhibit translation of natural mRNA templates but have no significant effect on poly(A)-dependent translation. Here we show that various oxazolidinones inhibit ribosomal peptidyltransferase activity in the simple reaction of 70 S ribosomes using initiator-tRNA or N-protected CCA-Phe as a P-site substrate and puromycin as an A-site substrate. Steady-state kinetic analysis shows that oxazolidinones display a competitive inhibition pattern with respect to both the P-site and A-site substrates. This is consistent with a rapid equilibrium, ordered mechanism of the peptidyltransferase reaction, wherein binding of the A-site substrate can occur only after complex formation between peptidyltransferase and the P-site substrate. We propose that oxazolidinones inhibit bacterial protein biosynthesis by interfering with the binding of initiator fMet-tRNA(i)(Met) to the ribosomal peptidyltransferase P-site, which is vacant only prior to the formation of the first peptide bond.
BACKGROUND: For patients presenting with atrial fibrillation of only a few weeks duration, the use of transesophageal echocardiography offers the opportunity to markedly abbreviate the duration of atrial fibrillation before cardioversion. We sought to determine if the shorter duration of atrial fibrillation allowed by a transesophageal echocardiography strategy had an impact on the recurrence of atrial fibrillation and prevalence of sinus rhythm during the first year following cardioversion. METHODS: Transesophageal echocardiography was attempted in 539 patients (292 men, 247 women; 71.6 +/- 13.0 years.) with atrial fibrillation > or =2 days (66.1% <3 weeks) or of unknown duration before elective cardioversion of atrial fibrillation. Therapeutic anticoagulation at the time of transesophageal echocardiography was present in 94.6% of patients, and 73.4% of subjects were discharged on warfarin. RESULTS: Atrial thrombi were identified in 70 (13.1%) patients. Successful cardioversion in 413 patients without evidence of atrial thrombi was associated with clinical thromboembolism in 1 patient (0.24%, 95% confidence interval: 0.0--0.8%). In patients with atrial fibrillation <3 weeks at the time of cardioversion (a duration incompatible with conventional therapy of 3 to 4 weeks of warfarin before cardioversion), the 1-year atrial fibrillation recurrence rate was lower (41.1% vs. 57.9%, P <0.01), and the prevalence of sinus rhythm at 1 year was increased (65.8% vs. 51.3%, P <0.03). No other clinical or echocardiographic index was associated with recurrence of atrial fibrillation or sinus rhythm at 1 year. CONCLUSIONS: Early cardioversion facilitated by transesophageal echocardiography has a favorable safety profile and provides the associated benefit of reduced recurrence of atrial fibrillation for patients in whom the duration of atrial fibrillation is <3 weeks.
DNA polymerase beta (polbeta) is an essential enzyme for gap filling synthesis in damaged DNA template involved in base excision repair pathway. A truncated polbeta protein is expressed in primary colorectal and breast adenocarcinomas. To determine a possible alteration in the functions of the enzyme, a human cell line named HeLapolbetadelta expressing the truncated form of polbeta has been established. These cells revealed a significantly reduced level of repair activity evaluated by gap filling synthesis and polbeta activity. More importantly, the HeLapolbetadelta cells are hypersensitive to MNNG, a DNA alkylating agent. It appears from the responses that the gap filling synthesis of WT cells, a HeLa cell line overexpressing wild-type polbeta protein, was inhibited by HeLapolbetadelta protein.
OBJECTIVE: To prospectively evaluate the efficacy and safety of periprostatic local anaesthesia (LA) during prostatic biopsy guided by transrectal ultrasonography (TRUS), as 20-65% of men report moderate to severe pain, and there is anecdotal and published evidence that periprostatic anaesthesia improves patients' tolerance. PATIENTS AND METHODS: In all, 157 patients were prospectively recruited and sequentially randomized to receive either LA or no anaesthesia. Sextant biopsies were taken in all men but some had more than six biopsies. All were asked to complete questionnaires immediately after TRUS-guided biopsy and for the subsequent week, giving pain scores and recording any morbidity, including symptoms of infection; analgesic use was also surveyed. RESULTS: Patients given LA had significantly lower pain scores at the time of biopsy than those given no anaesthesia, with median (sd) pain scores of 1.53 (0.7) and 1.95 (0.65) (P < 0.001), respectively. In addition, there was a trend towards less analgesic use by those given LA, although this was not statistically significant. There was no difference in the amount of haematuria, haematochezia or haematospermia, or infection rate, between the groups. The additional cost and time of the procedure was minimal ( pound3.00 and 3 min/per patient, respectively). CONCLUSION: Periprostatic LA infiltration is a quick and simple procedure which significantly improves immediate pain with no added morbidity; we strongly advocate its use to improve patient tolerance of TRUS-guided prostate biopsy.
AIM: To evaluate the success rate and cost efficiency of primary antegrade ureteric stenting (antegrade ureteric stent insertion as a single procedure without preliminary drainage). MATERIALS AND METHODS: A policy of primary stenting was tested in 38 patients (50 ureters) with obstructive hydronephrosis, of acute or chronic onset and of benign or malignant origin. Patients with suspected pyonephrosis were excluded. Patients successfully primarily stented (group 1) were compared to a group stented as a traditional two-stage procedure (group 2). End point assessments were screening time, equipment used, procedure-related costs, bed occupancy and technical and clinical success rate. Using these cost and outcome measures, a cost-efficiency analysis was performed comparing the two strategies. RESULTS: 40/50 (80%) ureters were considered primary stent successes. The average procedure-related bed occupancy was 2 days (range 1-2 days). Simple equipment alone was successful in 16 cases. Van ( pound46/case). The mean screening time was similar for the two groups (13.5 min vs Andel dilatation catheters and peel-away sheaths were frequently used (23 ureters). Expensive equipment was rarely necessary (four cases) and average extra equipment cost was small 15.3 min; P > or = 0.05). There was a minimum saving of pound800 per successful primary stent. The cost-effectiveness of a primary antegrade stenting strategy was pound1229 vs pound2093 for secondary stenting. CONCLUSION: In carefully selected patients, the majority of obstructed ureters can be primarily stented using simple equipment. The reduced hospital stay and overall success rate significantly improves the cost competitiveness of antegrade ureteric stenting.
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This report presents the miniaturization of a HTS screen to identify inhibitors of prokaryotic transcription-translation in a 1536-well format. The in vitro assay design utilized the bacterial expression machinery to drive expression of a firefly luciferase reporter gene, which was read as an endpoint luminesence measurement. This multicomponent system permits identification of inhibitors at different steps in this pathway. Successful miniaturization required integration of homogeneous assay formats, robust liquid-handling workstations, and second-generation imaging systems. Comparison of data from a triplicate 1536-well screen of a subset of a target library that had been previously validated and followed up for hit confirmation in a 384-well plate format confirmed that triplicate screening yields data of higher confidence and quality, eliminates the time-consuming and potentially error-prone step of cherry-picking, and reduces the number of false positives and negatives. The substantial savings of reagents and reduction of the numbers of plates to process obtained in a 1536-well format as compared to a 384-well format allowed a full triplicate evaluation of the entire library of 183,000 compounds at lower cost and in less time. The triplicate-screen statistics are consistent with a highly reliable data set with a coefficient of variation of 14.8% and Z' and Z values of 0.57 and 0.25, respectively. This screen resulted in the identification of 1,149 hits (0.63% hit rate), representing a compound population at 2.5 standard deviations from the mean cutoff. Furthermore, the data demonstrate good agreement between IC(50) values derived for this assay in a 1536-well format and 384-well format.
Rotational digital subtraction angiography (RDSA) allows multidirectional angiographic acquisitions with a single injection of contrast medium. The role of RDSA was evaluated in 60 patients referred over a 7-month period for diagnostic renal angiography and 12 patients referred for renal transplant studies. All angiograms were assessed for their diagnostic value, the presence of anomalies and the quantity of contrast medium used. The effective dose for native renal RDSA was determined. 41 (68.3%) native renal RDSA images and 8 (66.7%) transplant renal RDSA images were of diagnostic quality. Multiple renal arteries were identified in 9/41 (22%) native renal RDSA diagnostic images. The mean volume of contrast medium in the RDSA runs was 51.2 ml and 50 ml for native and transplant renal studies, respectively. The mean effective dose for 120 degrees native renal RDSA was 2.36 mSv, equivalent to 1 year's mean background radiation. Those RDSA images that were non-diagnostic allowed accurate prediction of the optimal angle for further static angiographic series, which is of great value in transplant renal vessels.