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Biomedical subjects

A Vaidya

Publications and source records attributed to A Vaidya.

At least 19 recordsLinked to original sources
PubMed2006

Retrieval of abdominal organs for transplantation.

BACKGROUND: Organ retrieval and donor management are not yet standardized. Different transplant centres apply various techniques, such as single or dual organ perfusion, dissection in the cold or warm, and single or en bloc organ removal. These different approaches may cause inconvenience, especially when more than one organ retrieval team is involved. METHODS: Cochrane Library, Medline and PubMed were searched for publications on multiorgan donor/donation, retrieval technique and procurement. Levels of evidence and grades of recommendation were evaluated based on current advice from the Oxford Centre for Evidence-Based Medicine. RESULTS: Multiorgan donation itself does not compromise the outcome of individual organ transplants. Dissection of abdominal organs for transplantation is best performed after cold perfusion. Abdominal organs should be removed rapidly, en bloc, and separated during back-table dissection in the cold, particularly if pancreas or intestine is included. Perfusion itself should be carried out after single cannulation of the aorta with an increased pressure. CONCLUSION: Although the literature on organ retrieval is extensive, the level of evidence provided is mainly low. Nevertheless, optimized donor treatment and organ retrieval should increase the number and quality of cadaveric donor organs and improve graft function and survival.

Abdomen↗
PubMed2006

Tamoxifen therapy in encapsulating sclerosing peritonitis in patients after kidney transplantation.

Sclerosing encapsulating peritonitis (SEP) is a serious complication of long-term continuous ambulatory peritoneal dialysis (CAPD) associated with obstructive symptoms and sclerosis of the peritoneal membrane. We present two cases that were successfully treated with tamoxifen and corticosteroids. Case 1: A 40-year-old patient developed end-stage renal failure (ESRF) and was managed with CAPD. He was hospitalized with symptoms of small bowel obstruction. He underwent laparotomy confirming the diagnosis of SEP. The patient was given tamoxifen 20 mg twice a day. Case 2: A 55-year-old patient with ESRF secondary to membranous glomerulonephritis. After having a cadaveric renal transplant in 1978 that failed 20 years later, the patient returned to CAPD. Six years later he had an uneventful kidney transplant and the peritoneal dialysis catheter was removed. However, 8 months later he presented with symptoms of small bowel obstruction and gross blood stained ascites. He also underwent a laparotomy that confirmed the diagnosis of SEP after biopsy. The patient was started on 20 mg of tamoxifen twice a day. Both patients' symptoms were improved gradually with an increase of serum albumin and body weight. Tamoxifen may be useful in the treatment of patients diagnosed with SEP.

Adult↗
PubMed2004

Use of donor aorta for arterial reconstruction in paediatric liver and multivisceral transplantation.

BACKGROUND: Arterial reconstruction remains the most important technical issue in paediatric transplantation. The arteries of paediatric donors as well as recipients are small and friable. The aim of this study was to assess the use of the donor aorta as a conduit for arterial reconstruction in paediatric liver and multivisceral transplantation. METHODS: Between June 1994 and January 2002, 284 paediatric transplants, including 197 cadaveric liver and multivisceral transplants, were performed in children at this centre. Of these, 41 (20.8 per cent), including nine cadaveric liver transplants and 32 multivisceral transplants, were revascularized by donor aortic reconstruction. Patient demographics, types of donor arterial reconstruction, technical complications and incidence of hepatic artery thrombosis were reviewed. RESULTS: None of the 41 donor aortic reconstructions used in revascularization of paediatric liver and multivisceral transplants thrombosed. There were no bleeding complications and no pseudoaneurysms developed. CONCLUSION: Arterial reconstruction using donor aorta is a useful option with a low incidence of thrombosis in paediatric transplantation.

Aorta↗
PubMed2001

Diverse roles of metal ions in acyl-transferase ribozymes.

The dependence on metal ions for catalysis is one of the hallmark characteristics of ribozymes. Yet despite this universal reliance, the functional role of divalent ions in promoting RNA catalysis is manifold. In this study we elucidate some different roles metal ions play as catalytic cofactors, by comparing two functionally co-evolved acyl-transferase ribozymes. Earlier studies performed on the in vitro selected acyl-transferase ribozyme, E18 [Suga, H., Cowan, J. A., and Szostak, J. W. (1998) Biochemistry 28, 10118-10125], revealed the requirement of a fully hydrated (outer-sphere) Mg2+ ion for catalytic activity. Interestingly, one class of acyl-transferase ribozymes isolated from the same RNA pool as E18 displays a unique metal dependency and is believed to be interacting with inner-sphere coordinated Mg2+ ions. New results show that one of these inner-sphere coordinating ribozymes, HS01, assumes a cloverleaf secondary structure closely resembling E18, yet apparently facilitates a distinct catalytic mechanism. Furthermore, the nature of the RNA-metal interaction(s) in HS01 seems to be dictating a unique reaction mechanism that exhibits a titratable moiety at a near-neutral pK(a). In light of the critical role metal ions play in biochemistry and the proper function of RNAs, these results compare two distinct manners by which metals serve to promote the catalysis of the same reaction.

Acyltransferases↗
PubMed2001

Intraoperative T staging in radical retropubic prostatectomy: is it reliable?

OBJECTIVES: During radical prostatectomy, wide local excision of the lateral prostatic fascia and neurovascular bundle on the ipsilateral side of the tumor is advocated if nerve sparing is likely to result in a positive surgical margin. Our intent was to validate whether intraoperative T staging can predict the presence of positive surgical margins and aid in the decision of whether to perform nerve-sparing prostatectomy. METHODS: One surgeon performed 100 consecutive radical prostatectomies, and one pathologist interpreted the pathologic findings. Topographic distribution of tumor within the specimen was assessed intraoperatively by palpation. The margin status was similarly assessed. This tactile clinical impression was compared with the final pathologic findings. RESULTS: The surgical margins were positive in 39 (39%) of 100 cases. The intraoperative assessment of the margin status had a high false-negative rate and a sensitivity of only 7%. However, the specificity was 96%, because few margins were falsely positive. The overall accuracy was 62%, with a negative predictive value of 62%. The sensitivity of the intraoperative assessment of tumor location was 73%, and the positive predictive value was 65%. CONCLUSIONS: The results of our study indicate that the intraoperative assessment of the margin status is not accurate and thus cannot help determine which patients require excision of the neurovascular bundle. We believe the decision to preserve the neurovascular bundle should be based on the preoperative prognostic factors and the presence of an intact capsule covering the region of the gland adjacent to this structure.

Adenocarcinoma↗
PubMed2001

De novo muscle invasive bladder cancer: is there a change in trend?

PURPOSE: We reviewed our radical cystectomy series to determine whether the majority of patients present with muscle invasive bladder cancer. MATERIALS AND METHODS: The records of 184 radical cystectomies performed by 1 surgeon from 1992 to 1999 were reviewed, and all slides of presenting pathology were reviewed by 1 pathologist. The pathological stage of the tumor at presentation was noted in each case, and the number of muscle invasive tumors at presentation was compared to 2 earlier series. RESULTS: Radical cystectomy was performed for muscle invasive transitional cell carcinoma of the bladder in 176 cases and for other histology in 8. There were 101 (57.3%) patients with muscle invasive cancer at presentation compared to 84% and 91% in the 2 earlier series, respectively, which was a statistically significant decrease (p <0. 0001) in the number of de novo muscle invasive bladder cancers. Women were more likely to be diagnosed with muscle invasion primarily than men (85.2% and 50.7%, respectively), and younger patients (younger than 50 years) were more likely to present with superficial bladder cancer compared to those older than 50 years who were more likely to present with de novo muscle invasive bladder cancer. CONCLUSIONS: Analysis of our data supports the findings of the earlier series that the majority of patients present with muscle invasive bladder cancer. However, there is a significant decrease in the percentage of tumors invading the muscularis propria at presentation. Although this observation is encouraging, we emphasize that it is not as dramatic as the stage migration associated with prostate cancer, which may be largely attributed to the widespread use of prostate specific antigen for early detection. Therefore, we support the suggestion that therapeutic gains might follow from improved education regarding the signs and symptoms associated with bladder cancer, with enhanced focus on women and consideration of screening methods for those at high risk for bladder cancer.

Aged↗
PubMed2001

Periprostatic local anesthesia before ultrasound-guided prostate biopsy: an update of the miami experience.

INTRODUCTION: Transrectal ultrasound (TRUS)-guided biopsy is a very common office procedure for most urologists. Pain or discomfort associated with this procedure has been addressed recently by the use of periprostatic local anesthesia. We re-address this issue with an update of our experience and emphasize the crucial steps that contribute to the success of the technique. We also analyzed the subsequent intraoperative effects of injecting lidocaine into the area of the neurovascular bundles. MATERIALS AND METHODS: Between June 1999 and December 2000, 200 patients underwent TRUS-guided biopsies of the prostate. Patients were properly consented and subjected to the procedure using periprostatic nerve block with 10 cm3 of 1% plain lidocaine. An 'ultrasonographic wheal' was created between the rectal wall and the posterior aspect of the prostate and three or four different locations along the neurovascular bundles. Pain scores were evaluated with the visual analogue scale. RESULTS: TRUS biopsy of the prostate was performed in 200 consecutive patients using periprostatic local anesthesia, 40 patients (20%) had undergone previous prostate biopsy without anesthesia. The age of patients ranged from 44 to 75 years (mean 67). The number of biopsies ranged from 6 to 14. Mean time from introduction of the probe per rectum to the end of the procedure was 18 min. There were no instances of clinical infection, significant bleeding, urinary retention, diaphoresis or hypotension. The visual analogue scale ranged from 1 to 3 (mean 2). Intraoperative findings in 62 patients who subsequently underwent nerve-sparing radical retropubic prostatectomy were no different from the patients who had biopsies without a local anesthetic. CONCLUSION: TRUS-guided biopsy of the prostate is the procedure of choice for diagnosing prostate cancer. This procedure can be accomplished with minimal pain with the use of periprostatic local anesthesia. It is an easy, safe, acceptable and reproducible technique that we believe should be considered for all patients undergoing TRUS biopsy regardless of age or number of biopsies.

Adult↗
PubMed2001

Local anesthesia for ultrasound guided prostate biopsy: a prospective randomized trial comparing 2 methods.

PURPOSE: Since the introduction of prostate specific antigen (PSA) screening, asymptomatic men often undergo transrectal ultrasound guided prostate biopsy. This procedure may cause significant discomfort, which may limit the number of biopsies. We performed a randomized prospective study to compare periprostatic infiltration with 1% lidocaine with intrarectal instillation of 2% lidocaine gel before prostate biopsy. MATERIALS AND METHODS: From October 1999 to July 2000, 150 men underwent prostate biopsy at the Miami Veterans Administration and Jackson Memorial Hospital. Experienced senior residents performed all biopsies. Patients were randomized into 2 groups depending on the method of anesthetic delivery. A visual analog scale was used to assess the pain score. Statistical analysis of pain scores was performed using the Student t test. RESULTS: Ultrasound guided prostate biopsy was done in 150 cases. There was a statistical difference in the mean pain score after periprostatic infiltration and intrarectal instillation (2.4 versus 3.7, p = 0.00002) with patients receiving periprostatic infiltration reporting significantly less pain. CONCLUSIONS: Men should have the opportunity to receive local anesthesia before ultrasound guided prostate biopsy with the goal of decreasing the discomfort associated with this procedure. Our prospective randomized study indicates that ultrasound guided periprostatic nerve block with 1% lidocaine provides anesthesia superior to the intrarectal placement of lidocaine gel.

Adult↗
PubMed2000

Topographic mapping from the retina to the midbrain is controlled by relative but not absolute levels of EphA receptor signaling.

Topographic maps are a fundamental feature of sensory representations in nervous systems. The formation of one such map, defined by the connection of ganglion cells in the retina to their targets in the superior colliculus of the midbrain, is thought to depend upon an interaction between complementary gradients of retinal EphA receptors and collicular ephrin-A ligands. We have tested this hypothesis by using gene targeting to elevate EphA receptor expression in a subset of mouse ganglion cells, thereby producing two intermingled ganglion cell populations that express distinct EphA receptor gradients. We find that these two populations form separate maps in the colliculus, which can be predicted as a function of the net EphA receptor level that a given ganglion cell expresses relative to its neighbors.

Animals↗
PubMed2000

Metal ion binding sites in a group II intron core.

Group II introns are catalytic RNA molecules that require divalent metal ions for folding, substrate binding, and chemical catalysis. Metal ion binding sites in the group II core have now been elucidated by monitoring the site-specific RNA hydrolysis patterns of bound ions such as Tb(3+) and Mg(2+). Major sites are localized near active site elements such as domain 5 and its surrounding tertiary interaction partners. Numerous sites are also observed at intron substructures that are involved in binding and potentially activating the splice sites. These results highlight the locations of specific metal ions that are likely to play a role in ribozyme catalysis.

Base Sequence↗
PubMed2000

Role of thermography in the assessment of infraorbital nerve injury after malar fractures.

We studied 45 patients with malar fractures who had some degree of infraorbital nerve deficit. Thermographic facial images failed to show any substantial changes in the temperature profiles of the affected and the normal control sides in relation to reco very of their facial sensation. Although some patients who had thermography on the day of injury showed significant temperature differences between the affected and the normal sides, these differences were probably the result of the acute inflammatory ch anges caused by the injury. We suggest that infrared thermography has little place in the assessment of infraorbital nerve deficits.

Adolescent↗
PubMed2000

Antibodies against ribosomal phosphoprotein P0 of Plasmodium falciparum protect mice against challenge with Plasmodium yoelii.

Antibodies against the Plasmodium falciparum P0 ribosomal phosphoprotein (PfP0) have been detected exclusively but extensively in malaria-immune persons. Polyclonal rabbit and mice sera were raised against two recombinant polypeptides of P. falciparum P0 protein, PfP0N and PfP0C, covering amino acids 17 to 61 and the remaining amino acids 61 to 316, respectively. Sera against both these domains detected a 35-kDa protein from Plasmodium yoelii subsp. yoelii, a rodent malarial parasite, and stained the surface of merozoites in immunofluorescence assays. Total immunoglobulin G (IgG) purified from rabbit and mouse anti-PfP0 sera by ammonium sulfate and DEAE-cellulose chromatography was used for passive transfer experiments in mice. Mice passively immunized with both anti-PfP0N and anti-PfP0C showed distinctly lower levels of parasitemia than control mice. With immunizations on days -1, 0, 1, 3, and 5, about 50% of both sets of mice receiving anti-PfP0N and anti-PfP0C cleared the lethal 17XL strain of P. yoelii and revived by day 25. All the control mice died by day 10. By extending the immunization schedule, the survival period of the mice could be extended for every mouse that received anti-PfP0 IgG. These data demonstrate the cross-protection of the anti-PfP0 IgG and establish parasite P0 protein as a target for invasion-blocking antibodies.

Animals↗
PubMed2000

Salvage radical prostatectomy for radiorecurrent prostate cancer: morbidity revisited.

PURPOSE: With the advent of prostate specific antigen (PSA) testing and transrectal ultrasound guided prostate biopsy there has been stage migration in the diagnosis of prostate cancer, so that more younger men are being diagnosed with organ confined prostate cancer. Many patients elect radiation therapy, while some have recurrent or new prostate cancer with absent systemic disease and life expectancy greater than 10 years. We present our experience with salvage radical prostatectomy in these cases. MATERIALS AND METHODS: Between 1995 and 2000, 6 men treated with curative intent with radiotherapy for prostate cancer were subsequently treated with salvage surgery for clinically localized prostate cancer. All men had biopsy proved recurrent or persistent prostate cancer, increasing serum PSA, no evidence of systemic disease at surgery and life expectancy greater than 10 years. We assessed the morbidity associated with this procedure and compared results to those in the contemporary literature. RESULTS: Six patients underwent salvage radical prostatectomy. Initial pre-radiation PSA was 4.5 to 15.7 ng./ml. Pre-radiation disease was clinical stage T1c in 5 cases and B2 in 1. The interval from radiotherapy to repeat biopsy was 12 to 48 months. A mean of 6.3 months after local recurrence was detected and before salvage radical prostatectomy was performed 4 patients underwent androgen deprivation therapy. Mean operative time was 195 minutes, intraoperative blood loss was 680 cc, and hospital stay and catheterization time were 3.2 and 13.8 days, respectively. There were no rectal injuries. All 6 patients are impotent, 5 are continent and 1 has mild stress incontinence. There was biochemical failure in 1 case 36 months after salvage radical prostatectomy and no evidence of recurrence in the remaining 5 at a mean followup of 27 months. CONCLUSIONS: Salvage radical prostatectomy is a technically challenging procedure. In the past it was associated with a high incidence of rectal injury, urinary incontinence and anastomotic stricture. The results of our relatively small series are encouraging and concur with those of recent studies that the morbidity of salvage radical prostatectomy is lower than previously reported. We believe that salvage radical prostatectomy may be considered a reasonable treatment option in appropriate patients with radiorecurrent prostate cancer.

Aged↗
PubMed1999

Extractive cultivation of recombinant Escherichia coli using aqueous two phase systems for production and separation of extracellular xylanase.

Recombinant Escherichia coli (pATBX 1.8) secreting extracellular xylanase was used as a model system to study the application of an aqueous two phase system for extractive cultivation. An increase in the polymer concentrations from 6 to 20% in the polyethylene glycol phosphate aqueous two phase system resulted in an increase in the phase volume ratio with a concomitant decrease in the partition coefficient (K) and recovery of xylanase in the top phase. However, varying phosphate concentrations from 8 to 16% decreased both the phase volume ratio and the partition coefficient of xylanase. The polyethylene glycol (6%) and phosphate (12%) system was found to be optimum for extracellular cultivation of E. coli, where extracellular xylanase was selectively partitioned to the top phase giving a purification ratio of above 1.0. The process was extended to a semicontinuous operating mode at the optimal condition, wherein the top phase containing xylanase was recovered and the surviving cells were recycled together with the new top phase. The maximum recovery of xylanase was obtained after 12 h in the top phase with a twofold increase in the specific activity as compared to the one obtained in the reference fermentation. In the present work, we report for the first time the use of the two phase system for the extractive cultivation of recombinant E. coli (pATBX 1.8) with the purpose of obtaining a simple and inexpensive separation procedure and achieving the maximal extraction of xylanase to one phase.

Bacteriological Techniques↗
PubMed1999

Azathioprine in refractory sprue.

We report a patient with life-threatening refractory sprue who was dependent on high doses of corticosteroids to prevent severe diarrhea, malabsorption, and villous atrophy. Azathioprine allowed tapering of corticosteroids to lower doses, while maintaining remission in histology and in objective measures of malabsorption. Immunosuppressive therapy, however, is not without risks, particularly in patients with associated hypoglobulinemia.

Adult↗