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Biomedical subjects

A Patel

Publications and source records attributed to A Patel.

At least 235 records · Page 13Linked to original sources
PubMed1998

Applications of electrical energy to the prostate: an evolutionary perspective.

PURPOSE: We review modern electrosurgical treatments for removing benign prostatic tissue based on an historical perspective of medical applications of electrical energy. MATERIALS AND METHODS: We reviewed historical reports and landmark observations concerning the evolution of medical applications of electrical energy in the literature, with a special focus on the development of principles pertinent to the transurethral electrosurgical removal of prostate tissue. RESULTS: Modern transurethral electrosurgery of the prostate in a fluid medium has been well founded on key electrosurgical principles. Traditionally, the best clinical results and the least complications have been obtained through an understanding of the important precepts of this form of energy. These precepts have included distinctions between the reliability of effect and safety with direct and alternating current, and how different tissue effects can be achieved, either with selective current modes (cutting and coagulating waveforms) or by varying the size and configuration of the active electrode and its application time. CONCLUSIONS: This review chronicles the prominent role of electrosurgery in our efforts to debulk an enlarged prostate in patients with symptomatic voiding dysfunction. History reminds us that many of today's "new ideas" are merely updated variations on a theme, have often been tried before in a fashion by our predecessors and have for one reason or another fallen by the wayside. The conundrum of the perfect combination of electrosurgical variables that can fulfill our goal of making this an efficient and complication-free treatment continues to stimulate and challenge us as we move towards the next millennium.

Electrosurgery↗
PubMed1998

New techniques for the administration of topical adjuvant therapy after endoscopic ablation of upper urinary tract transitional cell carcinoma.

PURPOSE: We evaluated the role of combining ureteroscopic tumor ablation and new methods of administering topical adjuvant therapy in select patients with transitional cell carcinoma of the upper urinary tract. MATERIALS AND METHODS: Patients with upper tract transitional cell carcinoma and indications for preserving renal function initially underwent ureteroscopic evaluation and tumor ablation. We treated 17 renal units in 13 patients. Three patients with distal ureteral lesions underwent uncomplicated adjuvant bacillus Calmette-Guerin therapy by the combination of Double-J stent placement and bladder instillations in the Trendelenburg position. In the remaining 14 renal units adjuvant topical therapy was administered by low pressure weekly instillations through a transvesical single-J stent whose curl was positioned in an upper calix. Patients were regularly followed with office flexible ureterorenoscopy under local anesthesia and cytology washings once they were confirmed to be tumor-free. RESULTS: Complete ureteroscopic tumor ablation was possible in all patients. Two sessions were needed due to tumor burden in 3 patients. There were intercurrent urinary infectious complications with Candida albicans in the 3 patients treated with bacillus Calmette-Guerin through the single-J stent, including 1 who received only 3 instillations due to persistent unexplained fevers but who remains disease-free at 24 months. In 2 of the 17 renal units multifocal tumor recurred within 12 months, which was treated with nephroureterectomy. At short followup (mean 14.6 months) 15 renal units have been preserved and remain tumor-free. CONCLUSIONS: The new techniques of administering adjuvant topical agents for upper tract transitional cell carcinoma after ureteroscopic tumor ablation in select cases described provide a useful and simple alternative to the percutaneous method preferred in the past. Short-term responses have been favorable but the true value of adjuvant therapy remains uncertain at present. The 2 recurrences within 12 months of treatment were readily detected by outpatient ureterorenoscopy with the patient under local anesthesia using 7.5F flexible endoscopes.

Adjuvants, Immunologic↗
PubMed1998

Infarct size-reducing effect of heat stress and alpha1 adrenoceptors in rats.

1. Noradrenaline (NA), which is abundantly released during heat stress (HS), is known to induce both delayed cardioprotection and heat stress protein (HSP) 72 expression by the mediation of alpha, adrenoceptors. Therefore, we have investigated the implication of alpha1 adrenoceptors in HS-induced resistance to myocardial infarction, in the isolated rat heart model. 2. Rats were pretreated with prazosin (1 mg kg(-1), i.p., Praz) or 5-methylurapidil (3 mg kg(-1), i.v., 5MU) or chloroethylclonidine (3 mg kg(-1), i.v., CEC) or vehicle (V) in order to selectively antagonize alpha1, alpha1A and alpha1B adrenoceptors. They were then either heat stressed (42 degrees C for 15 min) or sham anaesthetized. Twenty-four hours later. their hearts were isolated, retrogradely perfused, and subjected to a 30 min occlusion of the left coronary artery followed by 120 min of reperfusion. 3. Infarct-to-risk ratio was significantly reduced in HS+V (15.4+/-1.8%) compared to Sham+V (35.7+/-1.3%) hearts. This effect was abolished in Praz-treated (29.1+/-1.6% in HS+Praz vs 34.1+/-4.0% in Sham+Praz), 5MU-treated (34.5+/-2.2% in HS+5MU vs 31.2+/-2.0% in Sham+5MU) and CEC-treated (33.4+/-3.0% in HS+CEC vs 32.4+/-1.3% in Sham+CEC) groups. Western blot analysis of myocardial HSP72 showed an HS-induced increase of this protein, which was not modified by Praz, 5MU and CEC pretreatments. 4. We conclude that both alpha1A and alpha1B adrenoceptor subtypes appear to play a role in the heat stress-induced cardioprotection, independently of the HSP72 level. Further investigations are required to elucidate the precise role of HSPs in this adaptative response.

Adrenergic alpha-Antagonists↗
PubMed1998

Is there a clinically significant change in pressure-flow study values after urethral instrumentation in patients with lower urinary tract symptoms?

OBJECTIVE: To determine the effect of urethral instrumentation on pressure-flow study values and subsequent grading of bladder outflow obstruction (BOO) in men with lower urinary tract symptoms (LUTS) using suprapubic intravesical pressure monitoring. PATIENTS AND METHODS: Seventy-two men with LUTS underwent pressure-flow study using suprapubic intravesical pressure monitoring. The urethra was then instrumented successively with a 12 F catheter and a 17 F cystoscope, and a further pressure-flow study recorded after each procedure. Standard pressure-flow variables were measured for the three recordings. The presence and degree of obstruction were determined using commonly recognized grading systems, i.e. the Abrams-Griffiths nomogram. the linear passive urethral resistance ratio (LPURR) and the urethral resistance algorithm (URA). RESULTS: There were statistically significant differences in the detrusor pressure at maximum flow and detrusor opening pressure between the uninstrumented and instrumented studies (12 F and 17 F) but no difference in peak flow rates between the groups or in the Abrams-Griffiths number or URA value between studies. Using the LPURR, there was a tendency to a lower obstruction class after urethral instrumentation, ranking as 17 F > 12 F > no instrumentation. CONCLUSIONS: The changes seen after urethral instrumentation represent no more than the biological intra-individual variation normally seen in pressure-flow studies and do not lead to a clinically significant change in obstruction class.

Adult↗
PubMed1998

Air travel and thromboembolic complications after percutaneous nephrolithotomy for staghorn stone.

Thromboembolic complications after percutaneous surgery for staghorn stone are rare. We report a case of silent deep vein thrombosis (DVT) after long-distance air travel that was complicated by both recurrent pulmonary emboli and paradoxical arterial embolus despite full-dose systemic heparin anticoagulation. Management options for thromboembolic complications in the context of percutaneous renal surgery are discussed, and risk factors predisposing to silent deep vein thrombosis after long-distance air travel are outlined.

Aircraft↗
PubMed1998

Bacillus Calmette-Guerin (BCG) immunotherapy for bladder cancer: review of complications and their treatment.

BACKGROUND: Intravesical bacillus Calmette-Guerin (BCG) is widely used in the management of bladder cancer but because it is a living organism, local and disseminated infection may result. METHODS: A prospective assessment of complications of this therapy in 200 patients in Queensland was performed. A review of management of complications of intravesical BCG was also carried out. RESULTS: Major side effects were rare. Cystitis was the most common side effect, being seen to some degree in all patients, although only forcing cessation of BCG therapy in two patients. Two patients developed persistent cystitis necessitating institution of isoniazid and rifampicin. Two patients had culture-proven bladder infection that presented several months after the BCG treatment. These patients also responded to two-drug antituberculous therapy. While low-grade fever is very common with this therapy, seven patients (3.5%) had fevers of > 39 degrees C within 48 h of receiving BCG. Fevers may be an indication of severe disseminated mycobacterial infection, which has a high mortality, so it needs to be treated aggressively. Alternatively bacterial sepsis with gram-negative bacterial pathogens or a hypersensitivity reaction to BCG may cause this degree of fever, and cannot be rapidly distinguished from fulminant mycobacterial infection. One patient in the present series developed pneumonia attributed to mycobacterial dissemination. CONCLUSIONS: The key to appropriate management of complications of BCG therapy is awareness of their possibility, even months or years after the therapy has been given. Appropriate empirical therapy in acute situations and mycobacterial culture in chronic situations can then be performed.

Administration, Intravesical↗
PubMed1998

Omeprazole may exert both a bacteriostatic and a bacteriocidal effect on the growth of Helicobacter pylori (NCTC 11637) in vitro by inhibiting bacterial urease activity.

AIMS: To assess the potential antibacterial effect of omeprazole, a benzimidazole proton pump inhibitor, on the growth of Helicobacter pylori in vitro and to evaluate the effect of this compound on bacterial urease activity. METHODS: The growth of H pylori was observed in liquid culture in the presence and absence of omeprazole (0.8 mg/ml). Urease activity was evaluated in aliquots removed from two hour cultures by monitoring the initial change in absorbency at 560 nm in the presence of 0.02% phenol red. RESULTS: The minimum inhibitory concentration of omeprazole against H pylori was 0.8 mg/ml. The concentration of omeprazole required to inhibit growth was dependent on inoculum density: omeprazole (0.8 mg/ml) prevented growth from a 1 x 10(6) cfu/ml inoculum, but not from the higher inocula of 10(7) or 10(8) cfu/ml. This is the first study to demonstrate that omeprazole exerts a bacteriocidal effect against low bacterial densities and a bacteriostatic effect when bacterial density is high. When used at the onset of growth, this concentration of omeprazole has a bacteriocidal effect after four hours, although it exerts a bacteriostatic effect when added to cultures after the exponential phase. Bacterial urease activity is competitively inhibited by omeprazole in a dose dependent manner. CONCLUSION: The results suggest that omeprazole exerts both a bacteriocidal and a bacteriostatic effect against H pylori and competitively inhibits bacterial extracellular urease activity.

Anti-Ulcer Agents↗
PubMed1998

Effects of flooding amino acids on incorporation of labeled amino acids into human muscle protein.

We investigated the effects of the nature of the flooding amino acid on the rate of incorporation of tracer leucine into human skeletal muscle sampled by biopsy. Twenty-three healthy young men (24.5 +/- 5. 0 yr, 76.2 +/- 8.3 kg) were studied in groups of four or five. First, the effects of flooding with phenylalanine, threonine, or arginine (all at 0.05 g/kg body wt) on the incorporation of tracer [13C]leucine were studied. Then the effects of flooding with labeled [13C]glycine [0.1 g/kg body wt, 20 atoms percent excess (APE)] and [13C]serine (0.05 g/kg body wt, 15 APE) on the incorporation of simultaneously infused [13C]leucine were investigated. When a large dose of phenylalanine or threonine was administered, incorporation of the tracer leucine was significantly increased (from 0.036 to 0. 067 %/h and 0.037 to 0.070 %/h, respectively; each P < 0.01). However, when arginine, glycine, or serine was administered as a flooding dose, no stimulation of tracer leucine incorporation could be observed. These results, together with those previously obtained, suggest that large doses of individual essential, but not nonessential, amino acids are able to stimulate incorporation of constantly infused tracer amino acids into human muscle protein.

Adult↗
PubMed1998

Intelligent agent for collaborative diagnosis.

An agent-based approach to facilitating cooperative medical diagnosis is presented in this paper. Background work in computer supported cooperative work and medical informatics is first discussed. Relevant theory for interaction management is then considered. An agent-based interaction is then shown via a case study to facilitate cooperative diagnosis. This is achieved through monitoring patient record construction and by highlighting relevant diagnostic information.

Computer Communication Networks↗
PubMed1998

Biomechanical evaluation of the schuhli nut.

The schuhli out is a device designed to lock an AO 4.5-mm cortical screw to a 4.5-mm dynamic compression plate independent of bony contact with the plate. The nut engages the screw below the plate, elevating the plate, and locking the screw at a 90 degrees angle, thus preventing toggling. Photoelastic modeling and biomechanical testing on sheep tibias were done to determine the mechanical properties of constructs using schuhli nuts. Use of schuhli nuts was shown to decrease stress in the bone below the plate. The initial axial stiffness of a construct fixed with schuhli nuts is less than a construct with standard screws, but the rate of loss of stiffness with cyclic loading is similar. When a cortical defect is present at the near cortex and the screw engages the far cortex only, the use of a schuhli nut significantly improves the stability of the construct compared with a standard screw alone, and behaves mechanically the same as a standard construct with intact cortices. This indicates that the schuhli nut acts as a substitute for a deficient cortex. The schuhli nut can be useful in osteoporotic bone because it prevents the screw from stripping the threads in the bone as the screw is advanced. It also serves to lock the screw to help prevent the screw from backing out. The schuhli nut may be a useful tool to improve stability in the treatment of complex fractures, reconstructions, or in pathologic bone.

Animals↗
PubMed1998

Fibreoptic intubation through a laryngeal mask airway in an infant with Robin sequence.

Airway management is a major concern in Robin sequence, where micrognathia, glossoptosis and a cleft of the soft palate exist. The management of an infant with a potentially difficult airway is discussed where tracheal intubation was aided by the use of a 2.2-mm fibrescope mounted with a 3-mm endotracheal tube passed through a size 1 laryngeal mask airway.

Cleft Palate↗
PubMed1998

Serotyping scheme for Staphylococcus aureus isolated from cows with mastitis.

OBJECTIVE: To identify the Staphylococcus aureus capsular serotypes that are not typable, using capsular serotypes 5 and 8, which are currently used to type S aureus isolated from cows with mastitis. SAMPLE POPULATION: Milk samples (n = 273) from cows with mastitis in 178 dairy herds in California, Wisconsin, Michigan, Texas, and New York that were collected by state diagnostic laboratories and S aureus-positive milk samples collected by Veterinary Health Services in the United Kingdom (15), France (22), The Netherlands (36), and Germany (21). PROCEDURE: Capsular serotyping of coded isolates was performed by use of direct cell agglutination and immunoprecipitation of cell extracts with antisera specific for capsular types 5 and 8 and a newly developed S aureus serotyping antiserum 336. RESULTS: In the United States, S aureus capsular types 5 and 8 accounted for 18 and 23% of the isolates, respectively, and type 336 accounted for 59%. Percentage of capsular serotypes in European samples were as follows: type 5 = 34%, type 8 = 34%, type 336 = 30%, and nontypable = 2%. CONCLUSIONS: Serotypes 5 and 8 accounted for only 41% of S aureus isolates from US milk samples, but accounted for 70% of isolates from European milk samples. Addition of the newly developed serotyping antiserum 336 to the typing scheme accounted for 100% of US samples and 98% of European samples and will enable development of a more comprehensive S aureus vaccine.

Agglutination Tests↗
PubMed1997

One- to ten-year follow-up results of balloon angioplasty of native coarctation of the aorta in adolescents and adults.

OBJECTIVES: We attempted to evaluate the role of balloon angioplasty in the treatment of discrete coarctation of the aorta in adolescents and adults, with special emphasis on long-term results. BACKGROUND: Controversy persists over the use of balloon dilation for the treatment of native coarctation of the aorta. METHODS: Between July 1986 and January 1997, 43 consecutive adolescent and adult patients with discrete coarctation of the aorta underwent balloon angioplasty. One- to 10-year follow-up data of 37 patients, including results of cardiac catheterization and magnetic resonance imaging (MRI), form the basis of this study. RESULTS: No early or late deaths occurred. Balloon angioplasty produced a reduction in the peak to peak coarctation gradient from a mean +/- SD of 69 +/- 24 mm Hg (95% confidence interval [CI] 61 to 76) to 12 +/- 8 mm Hg (95% CI 10 to 14.8) (p < 0.001). Follow-up catheterization 12 months later (37 patients) revealed a residual gradient of 6.7 +/- 6 mm Hg (95% CI 4.6 to 8.9); 3 (7%) of 43 patients had suboptimal results with development of recoarctation, defined as peak gradient >20 mm Hg, with successful repeat angioplasty. A small aneurysm developed at the site of dilation in 3 (7%) of the 43 patients. MRI follow-up data 1 to 10.8 years (mean 5.2 +/- 2.7) after angioplasty (37 patients) revealed no new aneurysm or appreciable change in the size of the preexisting aneurysm in the three patients. The blood pressure had normalized without medication in 27 (73%) of 37 patients at follow-up examination. CONCLUSIONS: Balloon angioplasty is safe and effective and should be considered a viable alternative to operation for treatment of discrete coarctation of the aorta in adolescents and adults.

Adolescent↗