Gallbladder and bile duct stones: percutaneous therapy with primary MTBE dissolution and mechanical methods

The authors describe percutaneous treatment of gallbladder or bile duct stones in 18 patients who were poor surgical candidates or in whom conventional therapy failed. Dissolution was performed in most cases with methyl tert-butyl ether (MTBE) because of its potent dissolution properties; other solvents used included monooctanoin or chelating solutions. Gallbladder stones were eliminated in 11 of 13 patients (six of seven with dissolution alone, four of four with dissolution and basket extraction, one with basket removal alone). In five patients with stones in the common bile duct (n = 3), cystic duct remnant (n = 1), and intrahepatic bile ducts (n = 1), stones were eliminated with dissolution alone in two and with dissolution plus basket extraction in one. In two patients percutaneous therapy failed due to complications (vagal hypotension with bile peritonitis and transient respiratory arrest) that occurred during catheter placement. Preliminary results suggest that MTBE is effective for dissolution of many gallbladder stones and some bile duct stones. Noncholesterol solvents and adjuvant mechanical maneuvers are valuable adjuncts to achieve complete stone elimination.     

Urographic findings in homozygous sickle cell disease

A prospective study of the renal abnormalities on excretion urography in 189 patients with homozygous sickle cell disease is presented. Demonstrable abnormalities were present in 69% but there was no correlation with symptomatology. Calyceal clubbing was the most common abnormality occurring in 39% of cases and its incidence increased with age. An unexpectedly high prevalence (23%) of papillary necrosis occurred and both sinuses and cavities were demonstrated. The reasons for this high prevalence are discussed. The urographic findings did not correlate significantly with hematological features of the disease.     

Canine model of narcolepsy: Genetic and developmental determinants

Genetic and developmental factors were investigated in 101 cases of canine narcoleps-cataplexy syndrome. An experimental breeding program documented a probable autosomal recessive mode of inheritance in two dog breeds, Doberman pinschers and Labrador retrievers, and in crosses between those breeds. Age of onset of cataplexy and severity of symptoms were remarkably similar in 73 subjects with the genetically transmitted form of narcolepsy. Efforts to demonstrate genetic factors by breeding affected poodles and beagles were unsuccessful. Furthermore, a positive family history could not be documented in these animals or in narcoleptic dogs of 13 other breeds. Both age of onset and severity of symptoms were highly variable within this population. We suggest there may be multiple etiologies in canine narcolepsy syndrome: (i) inheritance via a single autosomal recessive gene, which appears to be identical in at least two unrelated dog breeds; (ii) nongenetic mechanisms which may include developmental or traumatic accidents. Preliminary findings of parallel neurochemical studies in narcoleptic dogs indicate distinct abnormalities in central neurotransmitter concentration and turnover. We theorize that these neurochemical abnormalities may result from inherited disorders of synthesis and/or metabolism which are present from birth or from nongenetic neurochemical abnormalities appearing later in life. The observation that symptom characteristics are identical in all affected dogs suggests that a common neurochemical disorder may underlie both genetic and nongenetic variations of the disease.     

The role of estrogen in pubertal skeletal physiology: epiphyseal maturation and mineralization of the skeleton

The year 1994 is likely to be remembered by many endocrinologists as the year in which dramatic new light was shed on the role played by estrogen in human skeletal physiology. It was in 1994 that two new syndromes were described, each representing a human model in which estrogen action was lacking. The first case was a female with an aromatase defect and a resultant inability to synthesize estrogen, and the second case was a man with an estrogen receptor gene defect that resulted in a non-functioning estrogen receptor and complete estrogen resistance. By examining the phenotypes of these two individuals, we were able, for the first time, to see what pubertal skeletal changes occur in the absence of estrogen action and directly extrapolate the role of estrogen in skeletal physiology. What has become abundantly clear is that it is estrogen and not androgen that is responsible for pubertal epiphyseal maturation and skeletal mineralization     

Comparing outcomes in renal replacement therapy: how should we correct for case mix?

The need to evaluate the effectiveness of clinical practice to justify expensive therapy in the face of financial constraints in all areas of health care delivery makes it necessary to identify groups of patients who are likely to benefit most from treatment. Various risk stratification methods have been used for analyzing survival probabilities for patients receiving renal replacement therapy. Complicated risk stratification methods produce large numbers of risk groups of small sizes, which makes comparison between individual centers difficult. We compared three simple methods of risk stratification, that divided patients into low-, medium-, and high-risk groups, in a cohort of 1,407 patients who commenced renal replacement therapy in five European countries during a 7-year period. Method 1 considered age (>55 years) and diabetes alone; method 2 used a higher age limit (>70 years) and comorbid illnesses, including those other than diabetes; and method 3 used only the number of comorbidities (none, 1, or > or =2) for stratification. Kaplan-Meier survival curves were constructed for comparison between risk groups and Cox's regression model used to assess strength of relationship with mortality. Although patient survival was significantly different between the low-, medium-, and high-risk groups using all three methods, Cox's regression analysis showed that method 2 provided the greatest discrimination between risk groups. In predicting mortality, method 2 (based on comorbidities and age) showed the highest sensitivity and specificity (84% and 80%, respectively) compared with method 1 (80% and 74%) and method 3 (64% and 82%). Validation of this approach in other populations in a prospective study is required before this method, which takes into account the influences of both age and comorbidity for risk stratification, can be used for comparing survival data and for presenting results of renal replacement therapy.