Antitrust aspects of exclusive contracts in medical imaging

Exclusive contracts between radiologists and hospitals may be more frequently scrutinized for antitrust violations because of the Hyde v Jefferson Parish Hospital District No. 2 case. In the Hyde case, the lower court decided antitrust law had been violated, and it was the first antitrust case about exclusive medical contracts to be reviewed by the U.S. Supreme Court. The case is a precedent for considering similar circumstances according to traditional business antitrust analyses such as per se violations, tying arrangements, group boycott, and market foreclosure. Areas that may be scrutinized for anticompetitiveness include hospital privileges when radiologists have exclusive contracts with the community's only hospital or provide services unique within an area, and physicians' access to scarce resources (e.g., computed tomography [CT], magnetic resonance [MR] imaging). Radiologists must understand antitrust implications of their hospital contracts; examine the terms of staff appointment, bylaws, and rights; and be able to guide their attorneys through contract negotiations.     

A proposed UVR protection factor for sunglasses

Solar ultraviolet radiation (UVR) has been long suspected as a causative factor in the aetiology of cataracts and recent scientific evidence has reinforced this viewpoint. The public and, in particular, outdoor workers need to take positive action to protect their eyes and the wearing of sunglasses can provide this protection. The Standards Association of Australia (SAA) has issued a standard covering the transmission requirements of sunglasses¹ (AS 1067 – 1990) and sunglasses complying with this standard offer substantial protection against ambient solar UVR. However, many sunglasses offer additional protection above that required by the standard. A UVR protection factor for sunglasses, analogous to the sun protection factor (SPF) for sunscreens, would allow the public to make an informed choice when purchasing sunglasses. Measurements of the transmittance of more than 250 pairs of sunglasses and protective eye wear have been made at the Australian Radiation Laboratory. Convolution of the spectral effectiveness of UVR on the eye (action spectrum) with the solar spectrum and the sunglass transmittance can give an estimate of the amount of protection different sunglasses offer. This method provides the means for rating sunglasses and producing the relevant protection factors. Calculations show that the concept of protection factor is viable for the different sunglass types.     

Food Cravings, Endogenous Opioid Peptides, and Food Intake: A Review

Extensive research indicates a strong relationship between endogenous opioid peptides (EOPs) and food intake. In the present paper, we propose that food cravings act as an intervening variable in this opioid-ingestion link. Specifically, we argue that altered EOP activity may elicit food cravings which in turn may influence food consumption. Correlational support for this opioidergic theory of food cravings is provided by examining various clinical conditions (e.g. pregnancy, menstruation, bulimia, stress, depression) which are associated with altered EOP levels, intensified food cravings, and increased food intake.     

Myeloperoxidase (MPO) gene mutation in hereditary MPO deficiency

Myeloperoxidase (MPO), present in the azurophilic granules of polymorphonuclear leukocytes, is a myeloid enzyme whose synthesis is restricted to promyelocytes. Complete hereditary MPO deficiency affects 1 in 2,000 to 4,000 individuals; however, the genetic cause of this defect is unclear. We have determined the molecular basis of MPO deficiency in one individual (SQ). Granulocytes of SQ had no MPO activity, and had complete absence of mature and precursor MPO protein by Western blotting. Scanning MPO gene structure by Southern blotting detected a novel BgI II fragment in SQ; no other alteration in gross gene structure was detected. We hypothesized that a single base pair mutation formed a new BgI II restriction site, and that this occurred in exon 10 of MPO gene. As predicted, exon 10 from SQ was cleaved by BgI II, but DNA from the normal patients and five other MPO-deficient patients was not cleaved by this enzyme. Direct sequencing of the polymerase chain reaction (PCR) product of exon 10 showed a C to T substitution at codon 569 in exon 10, resulting in arginine (CGG) to tryptophan (TGG) substitution and creating a novel BgI II site. The mutation was homozygous, as shown by both sequencing and Southern blotting, and no other alterations in base sequence were detected. To determine the frequency of this mutation, DNA was collected from 400 normal individuals, and the presence of the mutation was examined by digesting with BgI II after amplifying exon 10 by PCR. No other case with the novel BgI II site was detected, suggesting that this is not a restriction fragment length polymorphism. The rest of the coding region of the MPO gene was sequenced in DNA from SQ, as well as from the five other MPO-deficient individuals and one normal person; no other mutations were found. Our results suggest that a point mutation at codon 569 of MPO gene represents one molecular form of MPO deficiency.     

Intracerebral arteriovenous malformations: evaluation with selective MR angiography and venography

Magnetic resonance (MR) angiography and spin-echo methods were used to evaluate intracerebral arteriovenous malformations (AVMs) in 10 patients. Spin-echo images obtained with flow presaturation demonstrated the nidus of the AVM in all cases, but it was difficult to determine feeding vessels. These vessels were directly visualized with three-dimensional MR angiography; their presence could be indirectly determined by means of selective presaturation of individual vessels, which resulted in a marked decrease in signal within the portion of the AVM supplied by that vessel. Vascular supplies from the internal carotid artery and anterior, middle, or posterior cerebral arteries were detected in all cases, but in three large malformations it was not possible to demonstrate small feeding vessels. MR angiograms were also helpful for further defining the nidus. The combination of MR angiographic and spin-echo methods provides information useful for therapeutic planning not provided by either technique alone.