Re: Proportionate mortality among union members employed at three Texas refineries

OBJECTIVES:We established an in vitro model to investigate the effects of valve sizing on the hemodynamic characteristics and leaflet motion of the Toronto SPV valve (St Jude Medical, Inc, St Paul, Minn). METHODS: Nine valves were first implanted in fresh porcine aortic roots and then retested in glutaraldehyde-treated porcine aortic roots. Three valves were 1- to 2-mm oversized, 3 were 1- to 2-mm undersized, and there were 3 size-for-size implantations. The elasticities of the aortic roots and the composite roots were measured in the pressure range between 0 and 120 mm Hg, and the composite roots were then tested in a pulsatile flow simulator. The transvalvular gradient and regurgitation were measured and the effective orifice area and performance index were calculated for each root. Leaflet motion was recorded on videotape. RESULTS: The external diameter of the fresh root increased by 35% as the hydrostatic pressure rose from 0 to 120 mm Hg, as compared with 11% for the glutaraldehyde-treated root. Valve implantation in the fresh root reduced the distensibility to 22% but did not change distensibility in the glutaraldehyde-treated root. The effective orifice area was dependent on the valve size, with the transvalvular gradient decreasing as the valve size increased. For the same size of valve the hydrodynamic parameters were slightly better if the valve was undersized by 1 mm. A significant difference in favor of the undersized valves was found in open-leaflet bending deformation. CONCLUSION: Leaflet motion of the stentless porcine aortic valve in vitro is improved if the valve is slightly undersized, and this may be beneficial to the long-term durability of the prosthesis.     

Different manifestations of the antiphospholipid antibody syndrome in a family with systemic lupus erythematosus

OBJECTIVE: Familial associations of the antiphospholipid antibody syndrome (APS) offer the opportunity to study genetic mechanisms of autoantibody production and disease, but are unusual. We identified a family, including identical twins and their mother, in which all members had systemic lupus erythematosus (SLE) and presented with different manifestations of the APS. METHODS: Review of case histories and clinical laboratory results, antiphospholipid antibody (aPL) studies, complement C4 protein and gene analysis, and HLA typing of family members were performed. RESULTS: Each of the 3 family members presented with a different clinical association of the APS. These various clinical presentations were closely temporally related. No particular aPL activity could be separated out that would account for the different manifestations, although the twin with thrombocytopenia and livedo reticularis had a strikingly high IgM anticardiolipin antibody level. C4A or C4B deficiencies could not be implicated in the autoimmune process. However, the mother and the twins shared the HLA haplotype that included the class II antigens DR4, DRw53, and DQw7, which has previously been associated with aPL production. CONCLUSION: This family study emphasizes the different clinical associations of aPL production in SLE. In addition to genetic influences that appear to include HLA class II antigens, the clinical presentations also suggest an environmental trigger.     

Recombinant human factor IX: replacement therapy, prophylaxis, and pharmacokinetics in canine hemophilia B

Recombinant human factor IX (rFIX) has been expressed in transduced cultured cell systems since 1985. Because there has been limited in vivo testing of rFIX in hemophilia B subjects, this study was undertaken using the severe hemophilia B canines of the Chapel Hill strain. Three groups of hemophilic dogs received either 50, 100, or 200 IU/kg of rFIX. As a control, a fourth group of hemophilic dogs received 50 IU/kg of a high purity, plasma-derived human FIX (pdFIX). The coagulant and hemostatic effects of rFIX and pdFIX were similar with all comparative dosing regimens. Based on activity data, the elimination half-life of rFIX was 18.9 +/- 2.3 hours and pdFIX was 17.9 +/- 2.1 hours. A prophylactic regimen administering rFIX daily resulted in a continuous therapeutic level of plasma FIX and was accompanied by a two-fold increase in recovery levels by day 5, compared to that observed with administration of a single bolus. The mechanisms of the high to complete recovery of FIX with the prophylactic regimen could depend not only on the degree of saturation of the vascular endothelial binding sites but also on the altered dynamics of the balance of FIX distribution between the intravascular and extravascular compartments. The pharmacokinetic (PK) parameters for rFIX and pdFIX were similar. However, the relative PK values for V1 and V5s of both products on day 5 differed greatly from day 1 and may reflect the changing equilibrium of FIX between compartments with elevated levels of plasma FIX. Neutralizing antihuman FIX antibodies resulting from human FIX antigen being administered to FIX deficient dogs were observed beginning at 14 days. The antigenicity of rFIX and pdFIX appeared to be comparable. Despite the very different procedures used for production of rFIX and pdFIX products, in vivo testing in hemophilia B dogs showed the functional behavior of these products is similar; they are highly effective for replacement therapy and for prophylaxis.     

Clinical significance of urinary cyclic guanosine monophosphate in diagnosis of heart failure

In what approximated a controlled clinical trial for efficacy of seatbelts, the Colorado matched pairs study examined 256 crashes meeting the following criteria: driver plus front-seat passenger, one belted (SB) and one nonbelted (NSB) occupant, and at least one occupant injured. Nearly half (119 of 256) of the SB partners escaped injury, while only 16% (41 of 256) of the NSB group were as fortunate. To ascertain a differential effect the 160 pairs discordant for injury were analyzed. The relative odds for injury in the SB group was 0.34 (95% Cl: 0.24, 0.49) of that in the NSB group. Likewise, relative odds for any medical costs in the SB group was reduced to 0.24 (95% Cl: 0.14, 0.43) and for hospitalization to 0.29 (95% Cl: 0.10, 0.80). Sixty-five percent of the SB group had no medical costs in contrast to only 29% of the NSB group. Altogether the NSB group accounted for 76% of the medical costs and 72% of the hospitalizations. This study establishes the effectiveness of seatbelts in reducing nonfatal injuries using epidemiologic, financial, and medical data.     

Type I allergies to latex and the aeroallergenic problem

Between 1989 and 1995, a 12-fold increase in latex allergy was documented amongst our patients. Similar findings have been noted elsewhere. Increase in type I allergies to latex has become an international problem. The issues associated with latex allergy are described, including those posed by the ubiquitous nature of latex in medical equipment, and in commonplace domestic objects. The potential for allergic patients to cross react to a variety of fruits or plants is an added problem for sensitized patients. This paper concludes that the universal introduction of powder-free surgical gloves with low protein content would be a very important measure in the prevention of acquired latex allergy.     

Hepatocellular carcinoma: evaluation with dynamic and static gadobenate dimeglumine-enhanced MR imaging and histopathologic correlation

PURPOSE: To analyze the potential of gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging for the characterization and diagnosis of hepatocellular carcinoma (HCC) by using static and dynamic sequences. MATERIALS AND METHODS: Twenty-eight patients with histopathologically proved HCC were evaluated with T1- and T2-weighted spin-echo and static and dynamic gradient-echo sequences before, during, and after intravenous administration of 0.1 mmol/kg gadobenate dimeglumine (0.5 mol/L). RESULTS: During the perfusion phase of the dynamic sequence, all 16 nodular well-differentiated HCC lesions showed a rapid increase in signal intensity 10-30 seconds after injection followed by a progressive decrease in signal intensity. The nine poorly differentiated HCC lesions showed no rapid increase in signal intensity. All eight large (> 3 cm), nodular, well-differentiated HCC lesions showed a hypointense rim before injection and both hypo- and hyperintense rims (double-ring sign) immediately after injection, compared with normal liver parenchyma. About 55 seconds after injection, substantial single-rim enhancement was detected in 21 of the 28 HCC lesions. CONCLUSION: Dynamic gadobenate dimeglumine-enhanced MR imaging allows improved characterization of HCC lesions, which show rapid increase in signal intensity during the early, arterial phase in well-differentiated HCC lesions and a double-ring sign in large well-differentiated nodular HCC lesions.