PubMed Health⌕ Search

Biomedical subjects

R A Watson

Publications and source records attributed to R A Watson.

At least 19 recordsLinked to original sources
PubMed2000

Endourologic management of benign ureteral strictures with and without compromised vascular supply.

OBJECTIVES: To retrospectively assess the efficacy of balloon dilation, endopyelotomy/ureterotomy, and stenting alone in the management of benign ureteral strictures with intact or compromised vascular supply. METHODS: One hundred fourteen patients with benign ureteral strictures were assessed after at least a 2-year follow-up (range 2 to 16 years, mean 6.3). Balloon dilation was performed in 81, endopyelotomy/ureterotomy with temporary stenting in 27, and ureteral stenting alone in 6 patients. Ureteral strictures were divided into strictures with intact or with compromised vascular supply. RESULTS: Balloon dilation was successful in short ureteral strictures with intact vascular supply in 33 of 37 (89.2%), but only in 3 of 8 (37.5%) long ureteral strictures and in 1 of 2 (50%) recurrent ureteropelvic junction strictures. Balloon dilation was less successful when the vascular supply was compromised in 2 (40%) of 5 short strictures, 1 (16.7%) of 6 long strictures, and 2 (33.3%) of 6 recurrent ureteropelvic junction strictures. Endopyelotomy/ureterotomy was successful in 17 (89.5%) of 19 strictures with compromised vascular supply. CONCLUSIONS: Balloon dilation is recommended for management of short strictures with intact vascular supply. Endoureterotomy with stenting is recommended for all long ureteral strictures, for ureteropelvic junction stenoses, and for short ureteral strictures with compromised vascular supply and benign underlying etiology.

Adult↗
PubMed2000

Accuracy of diagnosis by guided biopsy of renal mass lesions classified indeterminate by imaging studies.

OBJECTIVES: To define the accuracy, safety, and impact of percutaneous biopsies of indeterminate mass lesions as an additional diagnostic tool. The vast majority of renal mass lesions are routinely diagnosed by radiographic features alone. However, with the increased use of computed tomography scanning and ultrasound, many smaller renal masses, which are "indeterminate" (refractory to categorization on the basis of imaging alone), are now being discovered. METHODS: We retrospectively reviewed 583 patients (364 male and 219 female) with indeterminate renal mass lesions diagnosed by imaging studies that were further investigated by percutaneous biopsy. Patients were followed up for at least 5 years if the biopsy result demonstrated a benign lesion, or they underwent surgical exploration if the biopsy result demonstrated a malignancy. Biopsy or aspiration material was assessed by histopathologic and cytologic evaluation and, when appropriate, with biochemistry, Gram stain, culture, and sensitivity. The biopsy site was localized by computed tomography, ultrasound, or fluoroscopy. RESULTS: Five hundred eighty-three patients with indeterminate renal mass lesions (representing 7.2% of all renal masses diagnosed from 1967 through 1996) were diagnosed by imaging studies complemented by guided biopsy. Sixty-six patients were lost to follow-up, leaving 517 patients who were analyzed. In 393 cases (76%), the imaging-guided biopsy provided a definitive diagnosis. The incidence of false diagnoses was 1.2% (7 biopsies). In 124 of the cases (21%), imaging-guided biopsy was unable to determine the etiology of the lesion with acceptable confidence; of these, 21 biopsies did not provide enough material to establish the diagnosis (16.9%). CONCLUSIONS: Overall, percutaneous biopsy of the kidney has proved to be a safe and accurate diagnostic procedure, with impact on the management of cystic or solid renal lesions.

Adolescent↗
PubMed2000

Penile Kaposi's sarcoma preceded by chronic penile lymphoedema.

Kaposi's sarcoma localized to the penis with striking lymphoedema is extraordinary. We report a middle-aged Haitian man who was human herpesvirus-8 seropositive, without evidence of immunosuppression or human immunodeficiency virus infection. He was first seen with Kaposi's sarcoma of 6 months duration localized to his penis, preceded by a 3-year history of chronic penile lymphoedema. His tumour regressed completely after radiotherapy. We propose that chronic lymphoedema in this patient predisposed to the development of Kaposi's sarcoma.

Humans↗
PubMed1999

Percutaneous nephrostomy as adjunct management in advanced upper urinary tract infection.

OBJECTIVES: To determine by retrospective review of 315 percutaneous nephrostomies, performed for pyonephrosis, whether this intervention has major clinical advantages. METHODS: From 1977 to 1996, under the direct supervision of the senior author of this report (E.K.L.), at seven hospital sites, 315 patients (181 males, 134 females; 17 to 88 years of age) were treated with percutaneous nephrostomy and antibiotic therapy for infected hydronephrosis. RESULTS: Additional or disparate pathogens were identified in 116 (36.8%) of 315 patients, leading to a clinically significant change in, or addition of, antibiotics and/or antifungal agents in 84 (73%) of 116. Most notably, we often found a clinically important disparity between the results of cultures obtained from the nephrostomy and those obtained from bladder-urine specimens. CONCLUSIONS: This retrospective review confirms previously reported advantages of percutaneous upper urinary tract drainage as a potentially life-saving adjunct in the treatment of pyonephrosis. Several case studies highlight the advantage of this maneuver in difficult cases involving obstruction due to extensive fungus or debris. In particular, our review focuses attention on the clinically important insight that urine cultures from percutaneous nephrostomy drainage often identify pathogens that differ from those detected in concurrent bladder cultures.

Humans↗
PubMed1998

Abdominal compartment syndrome.

BACKGROUND: The abdominal compartment syndrome (ACS) is a newly appreciated and potentially fatal consequence of increased intra-abdominal pressure. It can be due to either trauma or surgery, as well as numerous medical conditions. Prolonged, unrelieved elevation of intra-abdominal pressure can produce pulmonary compromise, renal impairment, cardiac failure, shock, and death. A high index of suspicion is imperative. Measurement of the intravesical pressure provides a urometric window for detecting and monitoring this condition. CONCLUSIONS: Reopening the abdominal incision (decompressive celiotomy) has proven a life-saving intervention. Use of delayed wound closure (staged celiotomy) may prevent development of this condition in high-risk surgical patients. It is urgent that all physicians, and surgeons in particular, be alerted to this potentially lethal complication.

Abdomen↗
PubMed1998

Use of mouth pressure twitches induced by cervical magnetic stimulation to assess voluntary activation of the diaphragm.

There is a need for a simple method to assess the adequacy of diaphragm activation during voluntary inspiratory efforts in patients with suspected respiratory muscle weakness. We have compared mouth (Pmo,t), oesophageal (Poes,t) and transdiaphragmatic (Pdi,t) twitch pressure elicited by cervical magnetic stimulation (CMS) in five normal men (mean (SD) age 32.2 (1.8) yrs) on two separate study days. Single magnetic stimuli were delivered at functional residual capacity during relaxation and during graded voluntary inspiratory efforts against a closed airway. As voluntary-effort transdiaphragmatic and oesophageal pressure increased, Pdi,t and Poes,t decreased linearly (r range, respectively, 0.82-0.98 and 0.87-0.95). During relaxation, Pmo,t was unreliable due to the poor transmission of intrathoracic pressure, but during inspiratory efforts, the relation between voluntary mouth pressure and Pmo,t was also linear (r range 0.84-0.95). On average, our subjects voluntarily generated 99, 100 and 102% of the maximum transdiaphragmatic, oesophageal and mouth pressures predicted by the respective linear regression equations. Pmo,t was correlated to both Poes,t and Pdi,t during inspiratory efforts, but not during relaxation. These studies confirm that twitch pressures induced by CMS during inspiratory efforts can be assessed at the mouth in normal subjects, providing a simple and non-invasive technique for assessing diaphragm activation during voluntary inspiratory efforts. Potentially, this technique could be made more sensitive and accurate and applied to detect submaximal efforts in patients.

Adult↗
PubMed1998

Placement of metallic stents in ureters obstructed by carcinoma of the cervix to maintain renal function in patients undergoing long-term chemotherapy.

OBJECTIVE: Metallic stents, sometimes augmented by "J" endostents, were placed in ureters obstructed by advanced carcinoma of the cervix to improve or maintain renal function in these patients at a level necessary to pursue long-term chemotherapy and radiation therapy. SUBJECTS AND METHODS: Seventeen ureters in 11 patients were treated with metallic stents, which were placed by an anterograde approach in 10 patients and by a retrograde approach in one. An anterograde ureteroneocystostomy was necessary in two of the 11 patients. J endostents were placed for I month in all patients. In 10 ureters, J endostents were reintroduced during follow-up 1-48 months later. RESULTS: In 17 ureters, metallic stents were successfully placed; in the remaining three ureters, the procedures were aborted because of technical difficulties. The goal of improving and maintaining renal function was met in 10 patients. Serum creatinine levels returned to normal in four patients and stabilized at a range of 2.7-3.2 mg/dl in six more patients, permitting treatment with chemotherapy, radiation therapy, or both. Four of the 11 patients died within 4 months after treatment, and three more died within 2 years. At the time of death or last follow-up, seven metallic stents and eight combinations of metallic stents and J endostents were patent. Complications were minor. CONCLUSION: Placement of metallic stents is recommended as an effective method to ensure patency and to facilitate cystoscopic replacement of J endostents in ureters compromised by carcinoma of the cervix. Renal function can be maintained, allowing chemotherapy. Survival is governed by the effectiveness of chemotherapy and radiation therapy.

Adult↗
PubMed1997

Incidence of stool guaiac conversion following extracorporeal shock wave lithotripsy.

OBJECTIVES: To study, in a prospective fashion, acute traumatic effects on the gastrointestinal tract of patients treated by extracorporeal shock wave lithotripsy (ESWL). METHODS: Stool samples from each of 54 patients were tested before and after ESWL for conversion to hemoccult positive. A minimum of one negative pre-ESWL stool guaiac test was required for inclusion into the study. A minimum of two stool guaiac tests were done after ESWL to verify negativity. Patients who converted to a positive hemoccult test after ESWL were then evaluated by colonoscopy for the source of bleeding. RESULTS: Fifty patients completed the study. A single patient (2.0%) converted to a positive post-ESWL hemoccult test and was evaluated with colonoscopy. This patient was found to have two benign adenomatous polyps in the sigmoid and descending colon after treatment for a left renal pelvis calculus. An additional patient with a slightly positive post-ESWL conversion refused further evaluation. The overall post-ESWL conversion rate to guaiac positive, therefore, was less than 4% (2 of 51 patients). CONCLUSIONS: There is no evidence of significant trauma or detectable bleeding in the normal gastrointestinal tract caused by ESWL as measured by postprocedure stool guaiac testing. Guaiac testing of the stool after ESWL may unmask pre-existing gastrointestinal disease. Therefore a positive guaiac test after ESWL warrants further evaluation. This study reaffirms that ESWL is a safe, minimally invasive technique for the treatment of urolithiasis, without significant adverse side effects on the gastrointestinal tract.

Digestive System↗
PubMed1997

Use of nasal peak flow to assess nasal patency.

Nasal patency is usually assessed in the laboratory by measuring nasal airflow conductance (Gnaw); peak inspiratory and/or expiratory flow measurements via the nose (PIFna, PEFna) have been proposed as simple alternatives suitable for home monitoring of rhinitis. We have compared the scale of changes in PIFna and PEFna (measured with a pneumotachograph) with changes in Gnaw (measured by the forced-oscillation technique) when nasal patency was increased by a topical alpha-adrenergic agonist, xylometazoline (five control subjects, seven with seasonal rhinitis, studied when asymptomatic) or decreased by topical histamine (eight control subjects). In further experiments, we altered intrapulmonary airway calibre by having subjects inhale histamine or salbutamol aerosols and examined effects on the configuration of nasal flow-volume curves (six subjects with rhinitis and mild asthma). After topical xylometazoline, there was a mean 283% increase in Gnaw, 80% increase in PEFna, and 63% increase in PIFna. After topical histamine, there was a mean 72% decrease in Gnaw, 38% decrease in PEFna, and 39% decrease in PIFna. Inducing intrapulmonary airway obstruction sometimes obscured changes in nasal patency by removing the effects of added nasal resistance on expiration and preventing development of flow limitation in the nose on inspiration. Thus, after topical drug treatment to the nose, changes in Gnaw were considerably larger than in PEFna or PIFna, which were proportionately similar. Because PIFna is usually restricted by nasal flow limitation, it is probably superior to PEFna for assessing nasal patency. When effort is submaximal, intrapulmonary dynamic resistance is increased, or nasal dynamic resistance is low, PEFna and PIFna can give a misleading impression of nasal patency. These errors can be avoided by comparisons with mouth PEF and/or PIF, suggesting that nasal and mouth peak flow should both be measured during home monitoring.

Adult↗
PubMed1995

Comparison of four methods of assessing airflow resistance before and after induced airway narrowing in normal subjects.

Four methods for assessing airflow resistance were compared in seven normal adults at baseline and after inducing airway narrowing with inhaled methacholine. Airway resistance (Raw) was measured during panting at 1-2 Hz within a body plethysmograph; total lung resistance was measured by using an esophageal balloon during quiet breathing (RLq) and with doubling of frequency while maintaining the original tidal volume; total respiratory resistance (Rrs) was measured at 6 Hz during forced oscillation applied at the airway opening, and interruption resistance (Rint) was measured at midtidal expiratory flow. Three methods of obtaining Rint after airflow interruption were compared [smooth curve fit of mouth pressure (Pm) back extrapolated to valve closure; two-point linear fit of Pm back extrapolated to 15 ms after closure; and Pm at 100 ms after valve closure]. We found similar basal median values (cmH2O.l-1.s) of Raw (1.3), RLq (1.4), RL of double resting frequency (1.9), Rrs (1.7), and smooth curve fit of Pm back extrapolated to valve closure (1.5); basal values of two-point linear fit of Pm back extrapolated to 15 ms after closure (2.4) and Pm at 100 ms after valve closure (4.4) were considerably larger. After induced airway narrowing, all methods of measuring resistance showed significant increases; these were largest with RLq (median %change of 265) and smallest with the three Rint methods (median %change of 62-72). Rint and Rrs methods had poorer sensitivity for detecting bronchoconstriction than lung resistance of Raw. Of the Rint methods, end interruption pressure was the most sensitive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effects of posture on respiratory mechanics in obesity.

Increased abdominal mass in obesity should enhance normal gravitational effects on supine respiratory mechanics. We have examined respiratory impedance (forced oscillation over 4-26 Hz applied at the mouth during tidal breathing), maximum inspiratory and expiratory mouth pressures (MIP and MEP), and maximum effort flow-volume curves seated and supine in seven obese subjects (O) (mean age 51 yr, body mass index 43.6 kg/m2) and seven control subjects (C) (mean age 50 yr, body mass index 21.8 kg/m2). Seated mean total lung capacity was smaller in O than in C (82 vs. 100% of predicted); ratio of functional residual capacity (FRC) to total lung capacity averaged 43% in O and 61% in C (P < 0.01). Total respiratory resistance (Rrs) at 6 Hz seated was higher in O (4.6 cmH2O.l-1.s) than in C (2.2 cmH2O.l-1.s; P < 0.001); total respiratory reactance (Xrs) at 6 Hz was lower in O than in C. In C, on changing to the supine posture, mean Rrs at 6 Hz rose to 2.9 cmH2O.l-1.s, FRC fell by 0.68 liter, and Xrs at 6 Hz showed a small fall. In O, despite no further fall in FRC, supine Rrs at 6 Hz increased to 7.3 cmH2O.l-1.s, and marked frequency dependency of Rrs and falls in Xrs developed. Seated, MIP and MEP in C and O were similar; supine there were small falls in MEP and maximum expiratory flow in O. The site and mechanism of the increase in supine Rrs and reduction in supine Xrs and the mechanism maintaining supine FRC in obesity all need further investigation.

Airway Resistance↗
PubMed1993

Accuracy and sensitivity of the interrupter technique for measuring the response to bronchial challenge in normal subjects.

The interrupter technique is a non-invasive method for measuring airway calibre. Since the calculation of interrupter resistance (Rint) is critically dependent upon the analysis of the mouth pressure/time (Pmo(t)) curve obtained after flow interruption, we wanted to assess the relative merits of four different analyses of Pmo(t) curves, obtained under basal conditions and following methacholine-induced airway narrowing, in 10 healthy adults. Four methods of analysing the Pmo(t) curves were used to calculate Rint values: RintC-a smooth curve fit with back-extrapolation; RintL-two-point linear fit with back-extrapolation; RintEO-calculated from the pressure change after the post-interruption oscillations had decayed (end-oscillation); and RintEI-calculated from the pressure change at the end of the period of interruption. The airway response measured with the four Rint methods was compared with plethysmographic airway resistance (Raw). The sensitivity of the methods was determined by calculating a sensitivity index (SI), the change in resistance after challenge expressed in multiples of baseline standard deviation. Values of RintC were similar to Raw values under all conditions. Resistance values from the remaining Rint methods significantly exceeded Raw (mean basal difference: 0.13-0.34 kPa.l-1 x s; mean difference after challenge: 0.12-0.42 kPa.l-1 x s. Raw was the most sensitive method for detecting bronchoconstriction (doubling of Raw was equivalent to SI of 10.5). Of the Rint methods, RintEI gave the highest sensitivity index (SI = 3.1), with a 42% mean change; RintC produced the greatest proportionate change after challenge (55%), but with a lower SI (2.2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Paratesticular fibrous pseudotumor in a patient with Gorlin's syndrome: nevoid basal cell carcinoma syndrome.

An 18-year-old man with Gorlin's syndrome (the nevoid basal cell carcinoma syndrome) underwent excisional biopsy of a fibrous pseudotumor of the tunica vaginalis. Preoperative ultrasound confirmed the extraparenchymal nature of this paratesticular lesion, permitting a transscrotal approach. The pathophysiological considerations suggest that this finding (to our knowledge the first such case reported in association with Gorlin's syndrome) may be more than coincidental.

Adult↗
PubMed1989

Interaction of unfused tricyclic aromatic cations with DNA: a new class of intercalators.

Unfused tricyclic aromatic ring systems 1-6 with one or two cationic side chains have been synthesized and their interactions with DNA and synthetic polymers probed with a variety of techniques. Molecular mechanics calculations indicate that the torsional angle between ring planes in the minimum energy conformation of the tricyclic molecules can range from 0 degree to as high as 50 degrees depending on the type of rings and substituents. Viscometric titrations with linear and supercoiled DNA, linear dichroism, and NMR studies indicated that all compounds with torsional angles of approximately 20 degrees or less bind to DNA by intercalation. The more highly twisted intercalators caused significant perturbation of DNA structure. Unfused intercalators with twist angles of approximately 20 degrees have reduced binding constants, suggesting that they could not form an optimum interaction with the DNA base pairs. Unfused intercalators with twist less than 20 degrees formed strong complexes with DNA. The structures of these unfused intercalators are more analogous to typical groove-binding molecules, and an analysis of their interaction with DNA provides a better understanding of the subtle differences between intercalation and groove-binding modes for aromatic cations. The results indicate that intercalation and groove-binding modes should be viewed as two potential wells on a continuous energy surface. The results also suggest design strategies for intercalators that can optimally complement DNA base pair propeller twist or that can induce bends in DNA at the intercalation site.

Cations↗