Biomedical subjects
Publications and source records attributed to A D Smith.
A ureteral calculus was extracted ureteroscopically from a pelvic kidney in a child who had undergone two open pyelolithotomies, bladder reconstruction of cloacal exstrophy, and bilateral cross-trigonal ureteral reimplantations (Cohen procedure).
Twenty-five kidneys underwent nephrostomy puncture with placement of a pigtail catheter into an upper pole calyx for manometric recording during nephroscopy without a working sheath and with an Amplatz sheath with and without a Rutner adapter. Intrarenal pressures remained below 16 cm of water (H2O) at all times with the Amplatz sheath with or without a Rutner adapter, whereas without a sheath the pressures ranged from 15 to 31 cm H2O (i.e., pressures associated with significant pyelovenous and pyelosinus backflow). Similar results were obtained in monitoring intrarenal pressures during clinical procedures. A working sheath should be utilized for all percutaneous nephroscopic procedures to minimize the incidence of pyelovenous and pyelosinus backflow as well as of perirenal extravasation of the irrigation solution. Even with a wide-lumen ureteral catheter in place, drainage via the ureter is not sufficient to maintain the intrapelvic pressure in the physiologic range.
Scrotal scintigraphy is nearly 100 per cent accurate in identifying testicular torsion and can distinguish that condition, which requires an operation, from torsion of testicular appendages, which often can be treated nonoperatively. The technique is 90 per cent accurate in distinguishing epididymo-orchitis, epididymitis, and testicular abscess and is valuable in the follow-up of testicular torsion or inflammation. It can screen patients for varicocele, identifying possible candidates for spermatic venography and embolization. However, it has nothing to offer in the differential diagnosis of painless testicular masses.
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Percutaneous ureterostomy was performed bilaterally in 1 patient and unilaterally in another when easier methods of total diversion failed. This advanced endourological technique is most applicable in a thin patient with tortuous ureters.
During the last 4 years we performed ureteroscopy for diagnostic evaluation in 20 patients and for removal of mid or distal ureteral stones in 127. All of the diagnostic studies were successful. In the stone removal cases the success rate increased from 71 per cent for the 24 procedures done during the first 2 years to 92 per cent for the 60 procedures done in the first 9 months of 1985. The rate of ureteral injury in the entire series was 2 per cent and in only 9 of the 23 failures was an open operation necessary. The benefit of experience also was evident in the results reported by 28 medical centers, with a 78 per cent success rate at the 11 centers that had performed less than 20 procedures each and an 84 per cent success rate at the 9 centers that had done more than 50. Despite early frustration with ureteroscopy, the value of mastering the technique allows the urologist to proceed endourologically with minimum morbidity and without precluding further interventional procedures.
The peel-away introducer sheath set, originally designed for the antegrade insertion of the silicone rubber Universal stent, also is useful for antegrade or retrograde basketing of ureteral stones, negotiation of a dilated renal pelvis and tortuous ureter with minimal trauma, retrograde flushing of ureteral stones for percutaneous extraction, removal of dislodged stents from the renal pelvis and ureteral examination with a flexible endoscope or rigid ureteropyeloscope.
A total of 12 patients with absorptive hypercalciuria type II and 11 normal controls participated in a study to evaluate the effects of dietary protein levels on urinary calcium and oxalate excretion before and after a 1 gm. dose of oxalate. Two test periods were used during which calcium (less than 400 mg. per day) and oxalate were restricted. The first test was done under conditions of low dietary protein (12 per cent total caloric intake, 60 gm.) and the second test was done at a high protein level (25 per cent, 125 gm. protein). Twelve-hour urine specimens were obtained after dinner on day 3 of each diet (low and high protein) and again on day 4 when 1 gm. oxalate (spinach) was added to the dinner meal. The specimens were analyzed for calcium, oxalate and relative calcium oxalate saturation (concentration product ratio). There were no significant differences between the controls and subjects with absorptive hypercalciuria type II in oxalate excretion before the oxalate load on the low protein (controls 31.4 +/- 4.2 standard error, expressed as mmol. oxalate per mol. creatinine, and absorptive hypercalciuria type II 23.1 +/- 3.1) and high protein (controls 30.4 +/- 4.2 and absorptive hypercalciuria type II 28.8 +/- 5.9) diets. After the oxalate bolus the positive changes in oxalate excretion were 11.8 +/- 4.8 (low protein) and 17.8 +/- 4.7 (high protein) for controls, and 11.4 +/- 4.4 (low protein) and 31.8 +/- 5.2 (high protein) for patients with absorptive hypercalciuria type II. Thus, the increases in post-load urinary oxalate levels observed for controls and patients were greater on the high protein than on the low protein diets. After the oxalate load the increases in urinary oxalate and calcium oxalate supersaturation were significantly greater for patients with absorptive hypercalciuria type II than for control subjects for the high protein but not the low protein diets (p less than 0.05).
Nine patients with renal pelvic transitional cell carcinomas were selected for treatment with percutaneous resection because of a solitary kidney (3), bilateral synchronous disease (1), renal insufficiency (1), poor surgical risk (2) or preoperative evidence of a single, low grade, superficial tumor (2). Eight patients underwent second-look procedures 2 to 28 days postoperatively, at which time 6 received neodymium: YAG laser irradiation. Supplemental intracavitary therapy through the nephrostomy tube was given in 6 patients (mitomycin C in 1 and bacillus Calmette-Guerin in 5). Of those patients 2 had third-look procedures. Five patients remain free of recurrence with a followup of 3 to 28 months (mean 9.5 months). In the other 4 patients there was recurrent disease in the renal pelvis (3) or reappearance of positive cytology studies (1) 4 to 5 months postoperatively. Extrarenal tumor recurrence was not observed. Percutaneous surgery provided adequate information to assess tumor architecture, grade, invasiveness and multifocality, and the presence of contiguous mucosal abnormalities, which, along with positive cytology and a history of or concurrent tumors in other segments of the urinary tract, increased the likelihood of tumor recurrence. Second-look procedures appeared to be useful to assess the effectiveness of the initial procedure and to remove any residual disease. Our results suggest that percutaneous surgery can provide results similar to those of an open conservative operation, although further investigation is needed to determine the ultimate place of this technique.
Acetylcholinesterase (AChE) and nonspecific cholinesterase (nsChE) activities of lumbar ceresbrospinal fluid (CSF) from patients with a clinical or histological diagnosis of Alzheimer's disease have been compared with those of normal age-matched control patients and patients with dementia of non-Alzheimer aetiology. No significant differences in the AChE activity of lumbar CSF from histologically and clinically diagnosed Alzheimer's disease patients and normal age-matched controls were found, although they could be distinguished from controls and other dements by their lower lumbar CSF levels of nsChE activity and by their elevated ratio of AChE/nsChE. A lower level of AChE activity was observed in the lumbar CSF of patients with dementia of non-Alzheimer aetiology. The AChE and nsChE activities of ventricular CSF obtained at postmortem have also been examined. The AChE activity of the ventricular CSF of patients with histologically confirmed Alzheimer's disease was 66% lower than that of age-matched controls; these patients could also be distinguished from normals by their lower levels of nsChE and by the elevated ratio of AChE/nsChE activities. A molecular defect in the AChE in the ventricular CSF of Alzheimer patients is indicated by the finding that the enzyme failed to show inhibition by high concentrations of substrate. The lower level of AChE in ventricular CSF may reflect the changes in this enzyme in forebrain regions of Alzheimer patients. Although it is at present not possible to correlate the lower levels of nsChE found in CSF with any known brain pathology, the significantly altered ratio of AChE/nsChE activities in lumbar CSF may possibly form the basis for a diagnostic test of Alzheimer type dementia.
According to the encoding specificity principle, memory is best when encoding and retrieval conditions are compatible. Some researchers have suggested that older adults encode information in a general fashion and are less sensitive to the specific contextual aspects of a memory situation due to limited processing resources. We investigated the hypothesis that age interacts with encoding specificity. Young and old adults studied target pictures in the presence or absence of pictorial cues factorially varied at encoding and retrieval. If the older adults used the specific cuing information differently from the younger adults, age should have interacted with the encoding and retrieval variables. The results provided no evidence for such an interaction and indicated that both ages showed evidence of encoding specificity. To investigate the role of processing resources in encoding specificity, old and young adults also studied the pictures while simultaneously performing a digit-monitoring task. The divided-attention manipulation also did not interact with age, as both young and old adults showed encoding specificity effects of comparable magnitude in both control and divided-attention conditions.
A survey of patients in a general surgical ward was undertaken to establish biochemical and anthropometric standards which could be used to detect malnourished patients in hospital. Results of biochemical and anthropometric tests of nutritional status were compared with assessment by a clinician and the quick nutritional index of Seltzer. Triceps skinfold thickness and serum albumin concentrations indicated that 29% and 35% of patients, respectively, were undernourished compared with 16% by clinical assessment and 17% by the quick nutritional index. Significant correlations (p less than 0.001) between serum albumin and transferrin concentrations and arm muscle area were found for men but not for women. Poor nutritional specificity and sensitivity of some anthropometric and biochemical tests may account for the difference in the level of undernutrition found by these tests and clinical assessment. This shows the importance of the choice of test in influencing the level of undernutrition detected.
Symptomatic staghorn renal calculi were removed from 106 of 124 kidneys (85%) with percutaneous ultrasonic lithotripsy. All remaining fragments were less than 5 mm in greatest diameter, small enough to pass spontaneously. Use of two or more access routes was necessary in 91 kidneys (73%), and 29 patients (24%) required multistage nephrolithotripsy for complete stone removal. The total operative time averaged 162 minutes per patient. The average hospitalization period was 12.5 days, and the average convalescence time after discharge was 15 days. The most common adverse effect was bleeding necessitating transfusion (57%). Infection occurred in 27% of patients and may be intrinsic to removal of these infected stones. There was one death in the study group: a patient with multiple medical problems died of myocardial infarction. Successful stone extraction requires a clear understanding of renal anatomic features, properly placed access routes, and radiologic-urologic expertise. It is concluded that staghorn calculi can be safely and effectively treated with the use of percutaneous techniques.
Of 582 patients who underwent percutaneous nephrolithotomy, 4% had complications. The most common complications were fever (23%) and bleeding necessitating transfusion (12%). Extravasation was seen in 7% of patients and transient ureteral obstruction in 6%. Other complications included pneumothorax or hydrothorax, pneumonia/atelectasis, paralytic ileus, nephrostomy-tube dislodgment or urine drainage from the flank lasting more than 1 week, significant infection, urinoma formation, renal pelvic laceration, ureteral avulsion, ureteropelvic or ureteral stricture, bowel injury, or escape of stone fragments into the retroperitoneum. Seven patients (1%) required immediate surgery: four to repair renal pelvic lacerations, one to repair a ureteral avulsion, and two to control bleeding after nephrostomy-tube removal when embolization failed. Four patients required delayed surgery for ureteral or ureteropelvic junction strictures, which may have been caused by a tissue reaction to the stones rather than by the procedure itself. There were two deaths--one from respiratory failure in a patient with severe interstitial pulmonary fibrosis and chronic renal failure and the other from myocardial infarction in an obese diabetic patient with hypertension.
Percutaneous full-thickness incision and stenting of the ureteropelvic junction (endopyelotomy) relieved obstruction in 33 (87%) of 38 patients treated over a 2-year period. Proper placement of the percutaneous nephrostomy tract through a posterior middle calyx and of a guidewire across the ureteropelvic junction is necessary in order to gain access to the narrowed area with a rigid cutting instrument. Except in patients with long lesions, high insertion of the ureter, or an enormously redundant renal pelvis, endopyelotomy gives excellent results with less morbidity and a shorter recovery time than open pyeloplasty.
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A modified ELISA procedure is described which permits selective detection of monoclonal antibodies reactive with the native antigen. The essence of the method is the use of immobilization methods that do not result in denaturation of the antigen during adsorption to the microtiter plates. This was accomplished by using polyclonal antibodies, adsorbed to the wells of the microtiter plate, as the immobilizing agent.
Antibodies against substance P and choline acetyltransferase (ChAT) have been used in a sequential double-immunocytochemical ultrastructural study of the rat forebrain. The peroxidase-anti-peroxidase procedure was used for both antigens, however, two different substrates for the peroxidase reactions were used. The substance P-immunoreactive sites were first localized using 3,3'-diaminobenzidine as the substrate, then the ChAT-immunoreactive sites were localized using benzidine dihydrochloride. The reaction product formed by the two substrates was distinguishable in both the light and electron microscopes. Using this procedure, the cell bodies and proximal dendrites of identified cholinergic neurons in the neostriatum were found to receive symmetrical synaptic input from substance P-immunoreactive boutons. A similar pattern of substance P-immunoreactive synaptic input was observed onto magnocellular basal forebrain cholinergic neurons in the ventral pallidum and ventromedial globus pallidus. In both the striatum and basal forebrain substance P-immunoreactive boutons were also seen in contact with structures that did not display ChAT immunoreactivity.