Biomedical subjects
Publications and source records attributed to S M Lang.
There has been a recent increase in the number of literature reports describing a severe neurological syndrome (Dialysis Dementia) seen in a small number of dialysis patients. This article reviews the current literature on the disease and its possible causes.
The mortality rate of critically ill patients with acute renal failure (ARF) has remained high. The impact of vigorous intermittent hemodialysis (IHD) on the outcome of ARF has not been validated. In this retrospective multicenter analysis, 154 patients with ARF were treated daily (intensive) or on alternate days (conventional) using complement and cell activating cuprophane (bioincompatible) or high-flux polysulfone dialyzer membranes with insignificant effects on circulating complement or cells (biocompatible). At initiation of IHD, all four groups were similar in patient characteristics and ARF factors. The use of synthetic membranes resulted in a reduced mortality rate (18% vs 45%; p < 0.001) and shorter duration of ARF (8 vs 15 sessions; p < 0.001). Daily IHD with cellulose based membranes tended to increase mortality rates compared with conventional cuprophane dialysis (37% vs 53%). Intensive IHD with polysulfone membranes resulted in a further decrease in overall mortality rates (15% vs 22%). This retrospective analysis shows that bioincompatibility of dialyzer membranes may be more important for the outcome of patients with ARF than the dose of dialysis. Its impact on outcome occurs independently of the dose of dialysis delivered.
Spinal Cord Injury Without Radiographic Abnormality (SCIWORA) is a commonly misdiagnosed injury in children and adolescents. Failure to recognize SCIWORA can lead to additional injury. The critical care nurse recognizes the risk of SCIWORA, conducts a complete neurologic assessment on children experiencing cervical trauma, and provides immediate immobilization to prevent further neurologic complications. These pediatric neurosurgical and trauma nurse authors describe the nurse's role and include a SCIWORA case study in this article.
OBJECTIVE: While most hypertensive patients with end-stage renal disease normalize high blood pressure with fluid removal by continuous ambulatory peritoneal dialysis (CAPD), there is a significant proportion of CAPD patients whose blood pressure can be controlled only by antihypertensive drugs. METHOD AND PATIENTS: To study the hypothesis that such patients are still volume overloaded, we used plasma cyclic guanosine monophosphate (cGMP) as a marker for hydration status. Thirty-two CAPD patients were divided into 3 groups: group 1, normotensive patients (n = 12); group 2, hypertensive patients who normalized their blood pressure with fluid removal (n = 12); group 3, hypertensive patients whose blood pressure was refractory to intensified fluid removal (n = 8). RESULTS: Mean cGMP levels were significantly higher in dialysis-sensitive hypertension (27 +/- 5 pmol/mL) than in dialysis-refractory hypertension (15 +/- 2 pmol/mL), or in normotensive patients (13 +/- 4 pmol/mL). Reduction of excess fluid in volume overloaded hypertensive CAPD patients resulted in a normalization of cGMP levels (14 +/- 8 pmol/mL), but did not affect this volume marker in patients with dialysis-resistant hypertension (10 +/- 4 pmol/mL). CONCLUSION: Plasma cGMP levels are elevated in volume overload-induced hypertension complicating CAPD. Hypertensive CAPD patients whose plasma cGMP levels are within normal limits have raised blood pressure refractory to volume removal. Our findings are consistent with the hypothesis that inadequate removal of excess volume plays a major role in a subset of patients with CAPD hypertension.
OBJECTIVES: Residual renal function (RRF) is of paramount importance to dialysis adequacy, morbidity, and mortality, particularly for long-term continuous ambulatory peritoneal dialysis (CAPD) patients. Residual renal function seems to be better preserved in patients on CAPD than in hemodialysis (HD) patients. We analyzed RRF in 45 patients with end-stage renal disease (ESRD), commencing either CAPD or HD, to prospectively define the time course of the decline in RRF, and to evaluate dialysis-technique-related factors such as cardiovascular stability and bioincompatibility. STUDY DESIGN: Single-center prospective investigation in parallel design with matched pairs. MATERIALS: Fifteen patients starting CAPD and 15 matched pairs of patients commencing HD were matched according to cause of renal failure and RRF. Hemodialysis patients were assigned to two dialyzer membranes differing markedly in their potential to activate complement and cells (bioincompatibility). Fifteen patients were treated exclusively with the cuprophane membrane (bioincompatible) and the other 15 patients received HD with the high-flux polysulfone membrane (biocompatible). MEASUREMENTS: Residual renal function was determined at initiation of dialytic therapy and after 6, 12, and 24 months. Dry weight (by chest x ray and diameter of the vena cava) was closely recorded throughout the study, and the number of hypotensive episodes counted. RESULTS: Residual renal function declined in both CAPD and HD patients, although this decline was faster in HD patients (2.8 mL/minute after 6 months and 3.7 mL/min after 12 months) than in CAPD patients (0.6 mL/min and 1.4 mL/min after 6 and 12 months respectively). It declined faster in patients with bioincompatible than with biocompatible HD membranes (3.6 mL/min vs 1.9 mL/min after 6 months). Eleven percent of the HD sessions were complicated by clinically relevant blood pressure reductions, but there were no differences between the two dialyzer membrane groups. None of the CAPD patients had documented hypotensive episodes. None of the study patients suffered severe illness or received nephrotoxic antibiotics or radiocontrast media. CONCLUSIONS: The better preservation of RRF in stable CAPD patients corresponded with greater cardiovascular stability compared to HD patients, independently of the membrane used. Furthermore, there was a significantly higher preservation of RRF in HD patients on polysulfone versus cuprophane membranes, indicating an additional effect of biocompatibility, such as less generation of nephrotoxic substances by the membrane. Thus, starting ESRD patients on HD prior to elective CAPD should be avoided for better preservation of RRF.
We demonstrate the development of a method for identification of human Ha-ras transcripts in cytological and histological preparations of rodent fibroblasts by RNA-RNA in situ hybridization. Fibroblasts, expressing human Ha- ras at high or a very low level, provide a biological model system to optimize in situ hybridization. For rapid detection we used the radiographic signal from cell smears, in directly overlaid x-ray film. Certain pretreatments of slides are shown to increase nonspecific probe binding. The methods described can be used for rapid detection of oncogene expression in small numbers of cultured cells, without prior extraction and purification of their RNA.