A comprehensive clinical validation of the nuclear stethoscope

Five studies were conducted to examine the degree of variability to be expected during the use of the non-imaging nuclear probe (BIOS Inc.) under a variety of clinical conditions. Comparison of the ejection fraction (EF) readings between the nuclear probe and a gamma camera showed good agreement, with the nuclear probe tending to underestimate lower, and overestimate higher camera EF values [mean (S.D.) difference, 0.84% (6.06)]. A comparison of two nuclear probes showed a small mean (S.D.) difference of EF readings of 0.063% (2.26). EF readings obtained in normal subjects 6 weeks apart were reproducible and differed by a mean (S.D.) of 0.23% (4.42). The administration of placebo to 10 normal subjects followed by sequential measurements for 4 h produced EF changes large enough to mimic a clinical effect, the largest hourly change observed being 5.4%, indicating the need for strict placebo control in interventional experiments. Data on four patients with heart failure showed small non-significant EF changes in the 1 h after placebo administration but a wide intra-subject range of ejection time and time to peak filling measurements. This highlights the problem of accurate, reproducible cursor placement in such patients. The nuclear probe is a portable, low cost instrument which produces accurate EF measurements when compared with the gamma camera.     

Beta-adrenergic blockade increases the hepatic extraction of glucose in sepsis

To determine the relationship between hepatic glucose clearance and elevated epinephrine levels in sepsis, dogs with gangrenous cholecystitis were anesthetized and received either propranolol hydrochloride (mean dose, 0.29 mg/kg) or saline solution before intraduodenal glucose injection (2.5 g/kg). The amounts of glucose, insulin, and glucagon in the portal vein, the hepatic artery, and the hepatic vein were determined from the concentrations and the blood flows in these vessels over a two-hour period. Normal dogs served as controls. The amounts of glucose, insulin, and glucagon reaching the livers of both septic groups were the same. However, propranolol treatment increased the percent of glucose extracted by the liver without affecting the extractions of insulin or glucagon. Propranolol reverses the limitation of hepatic glucose extraction in sepsis by a direct effect. Whether the extracted glucose is utilizable as an energy substrate needs to be established.     

Localization of a gene for otosclerosis to chromosome 15q25-q26

Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.