Paraneoplastic syndromes

Paraneoplastic syndromes (i.e. organ/tissue disorders associated with cancer) affecting the nervous system are thought to be the result of an autoimmune response triggered by specific cancer antigens. Several of these antigens have recently been identified and include the Hu, Yo and Ri proteins, with the Hu antigens being the best studied. Immunization of animals with HuD has been shown to retard the growth of HuD-positive neuroblastomas. In addition, the presence of anti-HuD antibody in humans with small-cell lung cancer predicts the slow growth of the tumor. The associated neurological disorders, however, limit the use of these and other antigens with similar characteristics in cancer vaccines.     

The incidence, morbidity, and mortality of surgical procedures after orthotopic heart transplantation

OBJECTIVE: The authors present their experience with patients having undergone orthotopic heart transplantation (OHT) in whom surgical conditions subsequently developed that required operative intervention. The incidence, morbidity, and mortality of these procedures are reported. SUMMARY BACKGROUND DATA: Several studies have evaluated the management options of biliary tract disease after OHT. Multiple reports of patients having undergone OHT who subsequently underwent peripheral vascular reconstructions, plastic reconstructive, and thoracic procedures also have been published. METHODS: A chart review of 349 patients who underwent OHT between 1985 and 1996 was conducted to identify surgical procedures that were required in the post-transplant period. Their outcomes are reported. RESULTS: Of 349 patients who underwent OHT, conditions requiring 94 surgical procedures developed in 54 patients (15%). Biliary tract disease developed in 17 patients (5%) who required cholecystectomy, 2 of the 5 patients with acute cholecystitis died. Eight patients (2%) underwent orthopedic procedures with no operative mortality. Flap advancements for sternal wound infections were performed in five patients and four deaths occurred. Seventeen thoracic procedures were performed in 11 patients with an overall mortality of 45%. Twenty-one vascular procedures were performed on 17 patients with 1 delayed death due to a malignancy. Seven patients underwent procedures of the colon and rectum with no mortality. Seven patients underwent repair of inguinal or incisional hernias with no mortality. Various infections occurred with one resultant death after operative intervention. Six procedures were performed for diseases of the small intestine with no resultant mortalities. CONCLUSIONS: Patients having undergone OHT and chronic immunosuppression are at increased risk of having complications develop from infection. Acute cholecystitis and sternal wound infection caused an inordinate risk of complications and death. Malignancies developed in four patients who required surgical intervention. A heightened awareness of coexisting peripheral vascular disease in patients transplanted for ischemic cardiomyopathy should exist. Close screening before surgery and surveillance after surgery to identify risk factors for infection and vascular disease and to screen for malignancies are essential.     

Methods of investigation in clinical cardiology. X. Studies on the evaluation of diagnostic tests in cardiology

Diagnosis is a complex cognitive process which is characterised by uncertainty. This uncertainty can be managed through specific knowledge in conjunction with probability theory. Studies evaluating diagnostic tests are the best way of building this knowledge. Studies evaluating diagnostic tests have two essential components: the gold standard and the new test. Both components, gold standard and test, are independent measurement process that can be influenced by diverse sources of variability. The comparison between diagnostic and test is essentially a hierarchical procedure. Diagnostic tests are evaluated by their sensitivity, specificity compared to a definitive gold standard. The predictive values and the likelihood ratio test are also used. Sensitivity (the proportion of true positives) and specificity (the proportion of true negatives) are values obtained from a sample and thereby can be considered as the conditional agreement between gold standard and the new test. Kappa coefficients for sensitivity and specificity are useful tools for adjusting both indices. Sensitivity and specificity are non-poblational values, they are estimates of the true values of the study population and can be affected by random error and systematic errors (bias). Confidence intervals are useful for giving an indication of the precision of the point estimates of sensitivity and specificity. A suitable sound design is required to avoiding a biased estimate of sensitivity, likelihood ratio, and predictive values. Finally a list of potential biases is given with methods for minimising these.     

Solitary rectal ulcer syndrome

BACKGROUND: Solitary rectal ulcer syndrome is a rare disorder characterized by erythema or ulceration of the rectal wall, associated with typical histological features, and disturbed defaecatory behaviour with the passage of blood and mucus. METHODS: This is a review based on a literature search using a computer database (Medline) and manual cross-referencing. RESULTS: The pathogenesis is likely to vary in different patients; it includes trauma from straining, direct digital trauma and possibly primary neuromuscular pathology. The histological findings of extension of the muscularis mucosa between crypts and muscularis propria disorganization on full-thickness specimens are characteristic. Biofeedback defaecation retraining, including habit training, can lead to symptom improvement and return to work in a majority of patients. Abdominal rectopexy offers long-term symptom improvement in approximately 50 per cent of patients. Rectal ulceration may persist after any treatment, even if symptoms improve. CONCLUSION: Behavioural therapy and carefully considered operations offer the best treatment results. Further work on psychological factors and neuromuscular and vascular pathology is required.     

The importance of pH in the regulation of ruminal acetate to propionate ratio and methane production in vitro

Grain feeding often causes a decrease in ruminal pH, and experiments were conducted to define the role of pH in regulating the acetate to propionate ratio and production of CH4. Cows that were fed 90% concentrate had lower ruminal pH values (6.22 vs. 6.86), higher VFA concentrations (85 vs. 68 mM), and lower acetate to propionate ratios (2.24 vs. 4.12) than did cows that were fed forage only. When mixed ruminal bacteria from cows that were fed 90% concentrate or 100% forage were incubated (48 h) with hay (10 g/L) or cracked corn (5 g/L) in a medium containing bicarbonate (38 mM) and tricarballylate (50 mM), the final pH values were less than 0.3 units lower than the initial pH. At final pH values less than 5.7, hay fermentation was inhibited, the acetate to propionate ratio and CH4 production declined more than twofold, and the inoculum source was without effect. Small amounts of H2 were detected at pH values less than 5.5. Total VFA production from cracked corn decreased when pH declined, but only if the inoculum was obtained from cows that were fed 90% concentrate. The acetate to propionate ratio of cracked corn incubations declined from 1.2 to 0.6 when final pH was decreased from 6.5 to 5.3, and CH4, as a percentage of total VFA production, also decreased. At pH values less than 5.3, the acetate to propionate ratio of cracked corn increased more than fourfold, and large amounts of H2 could be detected. Over the final pH range of 6.5 to 5.3, CH4 production was highly correlated with acetate to propionate ratio, which was dependent on pH and substrate (CH4 = 0.02 + 0.05 pH; r2 = 0.80). Calculations based on the differences between pH 6.5 and 5.8 indicated that as much as 25% of the decrease in acetate to propionate ratio could be explained by the effect of pH alone.