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Biomedical subjects

D E Johnson

Publications and source records attributed to D E Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1993

Integrated subacute care: 20% of your patient days.

New strategies are changing the profile of subacute care, and patients are beginning to move out of the hospital into subacute or home care services. It's a money-losing proposition for hospitals, writes Donald E.L. Johnson.

Aftercare↗
PubMed1993

Integrated systems face major hurdles, regulations.

As the Clinton health care reform plan is debated, hospitals are preparing their revised strategic plans. Donald E.L. Johnson looks at integrated health care delivery systems in light of state and federal regulations.

Comprehensive Health Care↗
PubMed1992

Sarcomatoid carcinoma of the prostate. A clinicopathologic study of 12 patients.

Sarcomatoid carcinoma of the prostate is a rare tumor that can be difficult to distinguish from a true sarcoma. The authors report 12 patients in whom the typical light microscopic appearance of prostatic adenocarcinoma was accompanied by the appearance of spindled or pleomorphic sarcomatoid areas within the same specimen or in subsequent accessions. Immunostaining or electron microscopic study demonstrated epithelial differentiation within the sarcomatoid area(s) in 6 of the 11 patients in whom special studies were performed. All nine patients for whom follow-up data were available died of disease within 3 to 48 months (median time until death, 12.0 months) after the appearance of the sarcomatoid carcinoma, and the clinical course in each instance was characterized by aggressive local recurrence. Our experience confirms that sarcomatoid carcinoma of the prostate is an aggressive variant of prostatic adenocarcinoma.

Aged↗
PubMed1992

Small cell carcinoma of the urinary bladder. A clinicopathologic analysis of 22 cases.

Small cell carcinoma of the urinary bladder is an uncommon tumor. The authors report the clinicopathologic findings in a series of 22 cases. Fifteen men and 7 women were studied; their ages ranged from 51 to 87 years (mean, 62.4 years). The most frequent presentation was hematuria (94.4%). At diagnosis, three patients had Stage B disease, six had Stage C, and ten had Stage D (unknown stage in three). Histologically, 6 were oat cell type tumors, 11 were of intermediate cell type, and 5 were of combined cell type. Immunohistochemical studies demonstrated positivity for neuron-specific enolase in ten of ten cases, cytokeratin in seven of ten cases, chromogranin in eight of nine cases, serotonin in seven of nine cases, and S-100 protein in four of ten cases. Neuroendocrine differentiation was seen in five of seven cases examined by electron microscopy. Treatment and follow-up data were available for 19 patients: 10 (52.6%) were dead of disease, 5 (26.3%) were alive and well, 3 (15.8%) were alive with disease, and 1 (5.3%) died of an unrelated cause. The 2-year survival rate was 50% for patients with Stage B, 25% for patients with Stage C, and 33% for patients with Stage D disease. Although overall survival was poor, some cases responded well to therapy. Based on the authors' experience, radical cystectomy with adjuvant chemotherapy appears to be the treatment of choice.

Aged↗
PubMed1992

Nd:YAG laser ablation of the prostate as a treatment for benign prostatic hypertrophy.

Many techniques have been used to relieve obstructive symptoms associated with benign prostatic hypertrophy. Transurethral resection of the prostate (TURP) with an electrocautery loop is the most commonly performed operation to relieve bladder neck and urethral obstruction caused by prostatic adenoma. There is increased interest in alternative therapies to reduce prostatic size for symptom relief in this condition. We describe a technique using the neodymium:YAG (Nd:YAG) laser and a 600-microns laser quartz fibre with an attached terminal gold-plated metal alloy reflector to provide reliable deep penetration into prostatic tissue for prostatic adenoma ablation. We report the first use of this technique in three patients with benign prostatic obstruction and one with localised adenocarcinoma of the prostate.

Carcinoma↗
PubMed1992

Pathologic changes occurring in the prostate following transurethral laser prostatectomy.

Serial gross and histopathologic examinations of the prostate following transurethral laser prostatectomy in the canine model demonstrated an immediate well-demarcated sphere of thermal necrosis measuring 2.7 cm in diameter, which, within 24 hours, had begun liquefaction and was showing multiple areas of cavitation. By the end of the 1st week, the areas of cavitation had coalesced to form a central cavity lined by a narrow layer of necrotic tissue clinging to the thin surviving peripheral belt of prostatic glandular parenchyma. At 3 weeks, the bluish-black discoloration resulting from breakdown of blood in the necrotic tissue had subsided, leaving masses of coagulonecrotic tissue within the central cavity. Within 5 weeks, the ectatic central cavity was lined by transitional epithelium. These postmortem pathologic observations confirm our surgical and clinical impressions of being able to satisfactorily perform an effective transurethral prostatectomy using neodymium:YAG (Nd:YAG) laser photoirradiation.

Animals↗
PubMed1992

Use of the holmium:YAG laser in urology.

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 mu with a maximum power of 15 watts (W) and 10 different energy-pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non-contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2-fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations.

Aluminum Silicates↗
PubMed1992

Transurethral incision of the prostate using the holmium:YAG laser.

Transurethral incisions of the prostate were made endoscopically in 5 dogs under a fluid medium using a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 microns and with delivery of 1.0 J/pulse in 15 Hz (15 W). Histopathologic examination of tissues collected immediately after surgery revealed irregular crevices outlined by a narrow zone of coagulative necrosis. Ulcerated fissures persisted at 5 and 7 days with the initial stages of epithelial regeneration partially re-epithelializing the ulcerated surfaces. A modest inflammatory response characterized by edema, hemorrhage, and a mixed inflammatory cell infiltrate was also associated with the laser incision sites at 5 and 7 days. Three weeks postlasing, the ulcerated surfaces of the fissures were completely re-epithelialized. At 5 weeks only a slight indentation persisted at the incision sites with minimal changes in the subjacent submucosa and prostatic glandular architecture. Although the results of these investigations are preliminary, we believe that the Ho:YAG laser warrants further clinical evaluation for treating patients with benign prostatic hyperplasia (BPH), urethral strictures, bladder neck contractures, and constrictions of the upper urinary tracts.

Aluminum Silicates↗
PubMed1992

Treatment of distal ureteral tumors using endoscopic argon photoirradiation.

This is the first report on the use of endoscopic argon photoirradiation to treat patients with low-grade ureteral tumors involving the distal ureter. Using a rigid ureteropyeloscope, a 300 mu or 600 mu quartz fiber, and 5 watts (W) of power in a continuous-wave mode, the lesions were ablated without complication. Patients remain free of ureteral recurrence after 5, 7, and 22 months. We conclude that the shallow (1 mm) depth of penetration and the ability to use the fiber in either a contact or noncontact mode provide the surgeon a large margin of safety and low risk of ureteral perforation.

Aged↗