Surgical and radiological decompression in malignant biliary obstruction: a retrospective study using multivariate risk factor analysis

We performed a retrospective computer-aided statistical study of 228 patients who received treatment for malignant biliary obstruction to compare survival rates after surgical or radiological biliary decompression. To adjust for the selection bias produced by the clinical choice of surgical vs. catheter drainage, we examined differences in survival rates after controlling for various clinical and laboratory factors, which are predictive of short and long-term survival. These factors were selected by multivariate analysis. Short-term survival was significantly correlated with preoperative metabolic status as reflected in serum albumin, and blood urea nitrogen (BUN) levels. Elevated serum bilirubin values had no additional negative effect on survival. Long-term survival was influenced mainly by the extent of the primary cancer and the preoperative presence of leukocytosis. Although there was a difference in the raw data for hospital mortality between patients who underwent surgical drainage (11%) and those who underwent radiological drainage (30%), we found no real effect produced by the form of therapy after controlling for prognosis variables, i.e., eliminating selection bias. We propose a simple statistical model to predict short-term hospital survival. The application of objective risk factor analysis according to accepted statistical methods should permit the assessment of new radiologic therapeutic techniques with greater clinical validity.     

A study of light-initiated currents in Limulus lateral eye retinular cells

Light-initiated currents in Limulus lateral eye retinular cells were studied using the voltage clamp technique. To assess the validity of such current measurements, the isopotentiality of retinular cells was determined on triply impaled cells and the effect of voltage clamping one retinular cell on adjacent retinular cells and on the eccentric cell in the same ommatidium was determined. The results of the experiments are: (1) retinular cells are isopotential at loci 100 μm apart; (2) appreciable steady state current during the clamping episodes leaks into neighboring retinular cells and the eccentric cell; (3) light-initiated currents exhibit two components; (4) there is a dynamic change in the resistance of the photoreceptor membrane during development of the receptor potential; (5) suppression of the rising phase (C₁) of the receptor potential does not affect subsequent voltage changes; (6) suppression of the sodium influx which normally produces C₁ has only minor effects on subsequent voltage changes; (7) reduced [KCl]_out increases and increased [KCl]_out decreases the reversal potential of light-initiated currents; and (8) reduced [NaCl]_out reduces the magnitude and the reversal potential of light-initiated currents.     

Severe acute pancreatitis after percutaneous biopsy of the pancreas

A retrospective review of 184 pancreatic biopsies in 178 patients was performed to assess the prevalence of severe postbiopsy pancreatitis. The size, contour, and pathology of the lesions biopsied; the course of the needle (i.e., through bowel or other viscera); the size of the needle; the number of needle passes made; and the guidance technique used were analyzed. Severe pancreatitis developed in five cases (five patients) 5/184 or 3% of the biopsies), usually within 24-48 hr. Three of the five patients who developed pancreatitis had true-negative biopsies (normal pancreas) proved either at surgery (two) or at clinical follow-up (one). The diagnoses for the two remaining patients were adenocarcinomas. In four of the five patients, the diagnosis of severe pancreatitis was made by inspection at surgery. The fifth case was diagnosed by CT. Three patients who underwent surgery and one patient who had percutaneous drainage recovered from the pancreatitis. The fifth patient died despite surgical intervention. All five patients with pancreatitis had masses 3 cm or smaller as compared with the overall group, in which 71 (39%) of the 184 biopsies performed had masses smaller than 3 cm. Overall, 18% of the biopsies were true negative, compared with the 60% true-negative rate in the pancreatitis group. The bowel was transgressed in 21% of all 178 patients, including three of the five pancreatitis patients. We conclude that although the risk of pancreatitis is exceedingly small in percutaneous needle biopsies, it may occur, and at a higher rate than previously reported.     

Immune tolerance mediated by recombinant proteolipid protein prevents experimental autoimmune encephalomyelitis

Proteolipid protein (PLP), a transmembrane protein expressed only in the central nervous system (CNS), is a candidate target autoantigen for autoimmune-mediated demyelination. We have evaluated the effect of a recombinant form of the PLP protein, ΔPLP4, in a murine model of experimental autoimmune encephalomyelitis (EAE). PLP-specific T-cell responses were observed following immunization of SJL/J, PL/J and SWR mice with ΔPLP4, demonstrating processing of the protein to several distinct antigenic epitopes. Clinical EAE associated with inflammation and demyelination in the CNS also developed after sensitization of mice with ΔPLP4 in adjuvant. Conversely, tolerance to ΔPLP4 in adult mice and prevention of PLP peptide 139–151-induced EAE was induced by intravenous injection of soluble ΔPLP4. The prevention of disease onset was paralleled by a significant reduction in demyelination and CNS inflammatory cell infiltration and diminished PLP139–151-specific T-cell proliferative responses. These results are consistent with the establishment of peripheral T-cell tolerance and reinforce the notion that recombinant myelin antigens and intravenous tolerance induction may prove useful in the modulation of the human demyelinating disease, multiple sclerosis (MS).     

Complicated pancreatic abscesses: problems in interventional management

Twenty-five patients with grade D or E pancreatitis underwent percutaneous drainage. These patients required multiple computed tomography (CT) examinations, multiple catheter insertions, multiple catheter manipulations, and long-term catheter drainage. Eight of the 25 patients were successfully treated with catheter drainage alone. Sixteen underwent surgical drainage, ten after attempts at percutaneous drainage and six prior to radiologic drainage. Of the ten patients who had initial percutaneous drainage, only four were clinically improved from the drainage procedure alone. Although the fluid component of the abscess was often adequately drained in all ten patients, surgery was required to remove pieces of necrotic debris. Six patients who underwent surgical debridement had residual abscesses in the post-operative period and were all successfully treated with percutaneous drainage. One patient died from unrelated causes. Successful interventional management of patients with pancreatic abscesses requires intensive radiologic intervention and monitoring and may be better served by a combination of radiologic and surgical means.     

Alveolar-arterial oxygen gradients versus the Neonatal Pulmonary Insufficiency Index for prediction of mortality in ECMO candidates

Current selection criteria necessary for intelligent application of extracorporeal membrane oxygenation (ECMO) in hypoxic neonates remains controversial. Both the Neonatal Pulmonary Insufficiency Index (NPII) and serial alveolar-arterial oxygenation gradient measurements (A-a)Do2 have been recommended. Accordingly, an analysis of 50 consecutive severely hypoxic neonates was undertaken to assess the predictive value of (A-a)Do2 determinations and NPII in discriminating survivors from non-survivors. These infants with meconium aspiration syndrome (MAS), congenital diaphragmatic hernia (CDH), or persistent pulmonary hypertension of the newborn (PPHN) required maximum mechanical ventilation for hypoxia. Pharmacologic manipulation of pulmonary vascular resistance was attempted in 83%. If postductal (A-a)Do2 remained greater than or equal to 620 torr despite 12 hours of maximum medical therapy, mortality was 100%; however, 35% of nonsurvivors were unfortunately excluded. (A-a)Do2 greater than or equal to 600 torr for 12 hours demonstrated 93.8% mortality, and only 12% of all mortalities were thus excluded. Among nonsurvivors successfully hyperventilated, the NPII could not predict mortality. Ideal selection criteria must exclude those who would otherwise survive without ECMO, yet allow early accurate identification of the neonate certain to die. It would appear that serial (A-a)Do2 determinations best permit this identification and thus orderly application of ECMO.     

Spectrum of unrecognized posterior urethral valves in the adult

The spectrum of symptoms and findings associated with posterior urethral valves can vary and mimic other conditions. Three cases of congenital posterior urethral valves in adult males are presented. Two patients were on dialysis with end-stage renal failure at the time of diagnosis after many earlier urologic evaluations. One patient subsequently received two cadaver renal transplants. The remaining patient presented with typical symptoms of prostatitis and was found to have posterior valves with a dilated posterior urethra and intraprostatic reflux on voiding cystourethrography.