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Biomedical subjects

G D Webster

Publications and source records attributed to G D Webster.

At least 91 records · Page 5Linked to original sources
PubMed1986

Nucleic acid binding drugs--XIV. The crystal structure of 1-methyl amsacrine hydrochloride; relationships to DNA-binding ability and anti-tumour activity.

The crystal structure of the 1-methyl derivative of the anticancer drug amsacrine [4'-(acridin-9-ylamino)-3'-methoxy-methanesulphonanilide+ ++] as its hydrochloride salt has been determined. The compound crystallizes in the monoclinic space group P21/n with cell dimensions a = 15.302(3), b = 8.035(2), c = 18.258(4) A and beta = 102.68(2) degrees, and has been refined to a final R of 0.055. The acridine chromophore is significantly non-planar, with a butterfly conformation about the C(9)-N(11) bond. The bonding geometry about the C(9) atom has been significantly altered compared to non-distorted amsacrine structures, as a result of this non-planarity. Energy calculations have been used to examine the flexibility of the molecule with respect to rotations about the C(9)-N(11) and N(11)-C(12) bonds, and with respect to intercalation into a dinucleoside duplex model for DNA. The latter calculations have been compared with solution DNA-binding and in vitro activity data for 1-methyl-amsacrine hydrochloride. The molecular modelling studies find that the energy of interaction between 1-methyl-amsacrine and a DNA intercalation fragment is significantly higher than for amsacrine itself, in accord with the biological data.

Amsacrine↗
PubMed1986

Perineal transpubic repair: a technique for treating post-traumatic prostatomembranous urethral strictures.

A perineal, 1-stage, end-to-end anastomotic repair is the preferred method to treat short (2 cm. or less) prostatomembranous urethral strictures. For longer strictures a combined perineal and abdominal transpubic approach is required. We describe a technique that has allowed a 1-stage perineal repair of such strictures, up to 5 cm. long, by wedge excision of the inferior portion of the pubis. This technique has been used in 4 patients with prostatomembranous strictures 2 to 5 cm. long. The results were uniformly good in all of these patients.

Humans↗
PubMed1986

Continent catheterizable urinary diversion using the ileocecal segment with stapled intussusception of the ileocecal valve.

A continent ileocecal reservoir was created as an alternative to ileal loop urinary diversion in 7 patients. In 3 patients the bladder neck was closed, the in situ bladder was augmented and a continent stoma was formed by intussusception of the ileocecal valve. In the remaining 4 patients an isolated cecal reservoir with a continent stoma replaced the bladder. Creation of a stoma that was continent and easy to catheterize was achieved by intussusception of the ileocecal valve with stabilization of the intussuscepted nipple using a Marlex collar. In most cases the cecal segment was hyperactive but this was controlled with anticholinergic medication. All 7 patients have a satisfactory capacity and a continent stoma without significant catheterization difficulties.

Humans↗
PubMed1986

Use of the rectus abdominis muscle flap in urological reconstructive procedures.

The rectus abdominis muscle flap has been used successfully in 4 reconstructive procedures complicated by tissue loss or urinary fistula. This simple procedure is advocated as an alternative to the use of omentum when prior abdominal surgery precludes omental mobilization. No adverse functional nor cosmetic result to the abdominal wall resulted.

Abdominal Muscles↗
PubMed1986

The urological evaluation and management of patients with myelodysplasia.

The urological evaluation and results of management of 183 myelodysplastic patients are presented. Our management protocol stresses upper tract and infection status surveillance during the early childhood years, and a clean intermittent catheterisation programme with pharmacological manipulation of detrusor and sphincter function as the optimal later management. Continence failures are few and are manageable by sphincter prosthetic surgery or bladder augmentation. Urodynamic results are valuable in children with difficult incontinence or poor upper tracts. The intermittent catheterisation programme reduces the incidence of symptomatic urinary infections in these patients, but the incidence of asymptomatic bacteriuria is high. The adverse results of supravesical diversion in myelodysplastic children rarely justify its use.

Child, Preschool↗
PubMed1985

Priapism: etiology, treatment, and results in series of 35 presentations.

Of 35 cases of priapism a successful outcome with detumescence of the erection and preservation of potency was achieved in only 6 instances. Patients with sickle cell disease enjoyed a more optimistic outcome, and early presentation appeared to be the key factor. The different therapeutic approaches did not have great impact on the outcome, and we advise an initial conservative approach progressing to glans-cavernosa fistula creation and subsequently to cavernosum-spongiosum shunting for patients failing to respond.

Adolescent↗
PubMed1985

Implantation of penile prostheses in patients impotent after priapism.

Review of recent implantations of penile prostheses done at Duke University Medical Center reveals 6 patients implanted for impotence secondary to priapism. Of these 6 patients, 5 had sickle cell anemia-induced priapism and 1 had idiopathic priapism. One patient had implantation of an inflatable prosthesis later followed by a semirigid prosthesis, 3 had implantation of a semirigid prosthesis, and 1 had an unsuccessful attempt at implantation of a semirigid prosthesis. The 5 patients with successful implantation have obtained satisfactory postoperative coital function. We believe that penile prostheses are beneficial in patients with impotence secondary to priapism. The degree of fibrosis encountered suggests that a semirigid prosthesis is more favorable, since the inflatable prosthesis may not overcome corporeal rigidity.

Adult↗
PubMed1985

The management of strictures of the membranous urethra.

We present 40 cases of posterior urethral stricture resulting from pelvic fracture injury or prostatectomy. The strictures were managed according to various factors but most important were stricture length and the absence of pathological conditions in the anterior urethra. Post-traumatic obliterative strictures less than 2 cm. long can be managed with excellent success via a 1-stage perineal bulboprostatic anastomotic repair. Combined abdominoperineal procedures are equally successful but are reserved for patients in whom the stricture is more than 2 cm. long or who have an associated bladder neck pathological condition. When associated anterior urethral disease mitigates against mobilization and extension of the urethra to accomplish an anastomotic repair, the vascularized island flap or 2-stage scrotal inlay procedure appears to be the optimal choice. Of 3 failures with full thickness skin grafts 2 may have been owing to suboptimal graft beds in the scarred pelvic floor and perineum. Direct vision urethrotomy is advocated for nonobliterative posttraumatic strictures, and the rationale for dilation rather than urethroplasty management of postprostatectomy strictures is presented.

Fractures, Bone↗
PubMed1985

Lumbosacral plexus stretch injury following the use of the modified lithotomy position.

The modified lithotomy position is used to provide simultaneous operative exposure to the abdomen and perineum. We report 3 lumbosacral plexus complications following use of this position. A mechanism involving stretch secondary to hyperabduction seems most likely. Electromyography is helpful in the diagnosis and the prognosis seems to be good.

Adolescent↗
PubMed1985

Urethroplasty management in 100 cases of urethral stricture: a rationale for procedure selection.

We performed 100 urethroplasties for urethral strictures that fulfilled our criteria for surgical intervention. Strictures were located in the pendulous urethra in 14 cases, bulbar urethra in 33 and membranous urethra in 32, while the entire urethra or multiple adjacent areas were strictured in 21. The etiology of the strictures was traumatic in 47 patients and inflammatory in 22, and no cause was identified in 31. One-stage repairs were performed in 76 cases. Anastomotic repairs were optimal for short traumatic strictures, with 1 failure among 29 cases. Full thickness skin graft repairs were performed for more lengthy inflammatory strictures in 34 cases, with 5 failures. Mitigating against success in these patients were extrapenile skin donor sites, tubed grafts and poor graft beds. Vascularized island flap repairs were performed in 13 patients with 1 failure but there was an associated problem of redundant repairs. Two-stage repairs were reserved primarily for long or multiple strictures, with 2 failures in 24 cases. We conclude that procedure selection should be determined by stricture characteristics, including location, etiology, length and the presence of local adverse factors. An over-all rate free of stricture of 91 per cent was achieved.

Adolescent↗
PubMed1985

The vascularized skin island urethroplasty: its role and results in urethral stricture management.

We report 11 vascularized island skin flap urethroplasties. Results appear to be excellent when the procedure is used for strictures of the pendulous urethra. Use of vascularized skin flap urethroplasties for the repair of bulbar and membranous strictures has been complicated by pseudodiverticula and stone formation, and in this portion of the urethra the technique probably should be reserved for cases in which local factors mitigate against alternative 1-stage procedures.

Adult↗
PubMed1985

Reliability, validity and efficiency of multiple choice question and patient management problem item formats in assessment of clinical competence.

Despite a lack of face validity, there continues to be heavy reliance on objective paper-and-pencil measures of clinical competence. Among these measures, the most common item formats are patient management problems (PMPs) and three types of multiple choice questions (MCQs): one-best-answer (A-types); matching questions (M-types); and multiple true/false questions (X-types). The purpose of this study is to compare the reliability, validity and efficiency of these item formats with particular focus on whether MCQs and PMPs measure different aspects of clinical competence. Analyses revealed reliabilities of 0.72 or better for all item formats; the MCQ formats were most reliable. Similarly, efficiency analyses (reliability per unit of testing time) demonstrated the superiority of MCQs. Evidence for validity obtained through correlations of both programme directors' ratings and criterion group membership with item format scores also favoured MCQs. More important, however, is whether MCQs and PMPs measure the same or different aspects of clinical competence. Regression analyses of the scores on the validity measures (programme directors' ratings and criterion group membership) indicated that MCQs and PMPs seem to be measuring predominantly the same thing. MCQs contribute a small unique variance component over and above PMPs, while PMPs make the smallest unique contribution. As a whole, these results indicate that MCQs are more efficient, reliable and valid than PMPs.

Clinical Competence↗
PubMed1985

An analysis of the knowledge base of practicing internists as measured by the 1980 recertification examination.

The performance of practicing internists on the American Board of Internal Medicine's 1980 Recertification Examination was examined in two studies. In the first study, a psychometric common-item equating technique was used to compare the performance of 1980 recertification candidates with that of 1979 certification candidates. Results showed that the knowledge base of practicing internists was similar to that of residents completing training. The second study analyzed the performance of 1980 recertification candidates to determine whether being certified or having an interest in a subspecialty affects a physician's performance on items in that area. The results showed that subspecialists do significantly better than general internists on items pertaining to their area of specialization. Similar outcomes were found for internists with a special interest in a subspecialty area. These findings establish the importance of continued periodic evaluation and support the development of an evaluation tool tailored to the physician's area of concentration.

Adult↗
PubMed1984

Urodynamic abnormalities in neurologically normal children with micturition dysfunction.

We evaluated by video urodynamic study 60 children between 4 and 16 years old who had presented with various combinations of urinary frequency, diurnal incontinence, enuresis, voiding symptoms, recurrent urinary infections and upper tract changes. A number of seemingly distinct categories of detrusor dysfunction could be identified, which may have a bearing on logical treatment selection. In addition, abnormalities of sphincter activity were noted in 12 children. The limitations and interpretation difficulties of urodynamic studies in children are stressed.

Adolescent↗
PubMed1984

Urethrovaginal fistula: a review of the surgical management.

Urethrovaginal fistulas may occur after external or surgical trauma and result commonly in urinary incontinence. Various repair procedures have been suggested. However, it appears that the Martius operation with labial fat pad interposition between the repaired urethra and vagina is as satisfactory as any.

Adolescent↗