The introduction of low-osmolar contrast agents in radiology. Medical, economic, legal, and public policy issues

This case study of the public policy implications of introducing a new technology in radiology, namely, low-osmolar contrast media (LOCM), raises the issues of whether and how to place appropriate limits on new technologies. Although these contrast media represent small episodic costs, they may add up to an aggregate expenditure of nearly $1 billion per year if used for all contrast injections. As a result, this technology raises a number of important medical, economic, legal, and public policy questions. Our cost-effectiveness analysis and an analysis of the medical evidence suggest that LOCM should be limited to high-risk patients. We discuss in this article how the legal system might respond to such limitations, and we consider various public policy options for adopting restrictions on use. We conclude that the medical profession should take the lead in developing protocols for appropriate assessment, reimbursement, and use of LOCM.     

Tumor vascular signals in renal masses: detection with Doppler US

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.     

Characteristics of the 19S and 7S response to bacteriophage ΦX174 in the fowl

After intravenous injection of 10¹⁰ plaque forming particles of ØX174 bacteriophage into White Rock fowls, immune elimination began at 30 hours and viable phage was cleared from the circulation by 50–52 hours, the approximate time at which detectable antibody appeared. Little change was noted in the serum neutralizing activity in the interval from 44 to 217 days after injection, at which time the birds were reinjected with ØX174.

Sephadex Peak I (19S globulin) accounted for most of the early activity of the primary response. By Day 9 most of the activity had shifted to Peak II (7S globulin). In the secondary response, the shift had occurred by Day 4. Both 19S and 7S globulin fractions showed an increase in activity when compared to the same days of the primary response, but the 7S increase was proportionately greater.

All sera and serum fractions (whether 19S or 7S) were sensitive to reduction with 2-mercaptoethanol, but became, less sensitive during the course of immunization.

With regard to the production of 19S antibody, White Rock fowls showed a different response to the particulate antigen ØX174 compared with the response to injection of the soluble antigen, bovine serum albumin. There is evidence of immunological memory in the 19S response to ØX174.

     

Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos

In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.      

Indications for peripheral light-chain revision and somatic hypermutation without a functional B-cell receptor in precursors of a composite diffuse large B-cell and Hodgkin's lymphoma

Composite lymphomas are rare combinations of Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma in the same patient, where clonal relatedness has been observed in most of the few cases analyzed. Here, we report a composite classical HL and diffuse large B-cell lymphoma (DLBCL) with interesting molecular features. Micromanipulation of single cells and analysis of V gene rearrangements revealed clonal relatedness with shared and distinct mutations, indicative of derivation from a common germinal center (GC) B-cell precursor and also of further development of both lymphomas in a GC. In the DLBCL, a very high mutation load, including inactivating mutations, and two copies of the same clonal rearrangement with different mutations in single cells were observed. Intriguingly, in the DLBCL precursor somatic hypermutation activity continued after acquisition of destructive V gene mutations, a feature previously found only in Epstein-Barr virus (EBV) infected B-cell expansions. Furthermore, we found evidence of light-chain receptor revision in the lymphoma precursor during a GC reaction. Re-expression of the V(D)J recombination machinery may enhance genomic instability in GC B cells and contribute to lymphomagenesis.     

Clinical and familial study of arrhythmogenic right ventricular cardiomyopathy

Objective　To explore the characteristics of arrhythmogenic right ventricular cardiomyopathy (ARVC). Methods　Seven patients with arrhythmogenic right ventricular cardiomyopathy and 34 members of three families were studied. All patients and family members underwent history collection, clinical examination, electrocardiogram (ECG), two-dimensional echocardiography (2-DE) and a signal averaging electrocardiogram. Programmed ventricular stimulation was performed in five patients. Results　All patients and family members had normal morphologic characteristics and normal function of the left ventricular by 2-DE. Fourteen persons had abnormal findings indicating ARVC. Five had enlargement of the right ventricular with diffused hypocontractility, eight had thin and systolic bulging in the focal anterior wall with hypokinesia and one had bulging of the inferior wall. Twenty-five persons (seven patients and 18 family members) had abnormal findings in ECG. Positive ventricular late potential was recorded in 13 persons (six patients). Two to three monomorphic ventricular tachycardia (VT) with left bundle branch block (LBBB) configurations were induced in five patients. Ventricular fibrillation was induced in two patients during the electrophysiologic study (EPS). Five patients had very high pacing threshold and/or ineffective pacing in one or many regions of the right ventricle. Two members of one family died suddenly. One member was a dwarf with ARVC. Spontaneous VT with a left bundle branch block (LBBB) configuration was recorded in five patients, polymorphic VT with extremely short coupling interval in one, and premature ventricular complexes with LBBB configuration in 12 (six patients). Conclusion　Our familial study strongly suggests that ARVC may be a hereditary disease and it is helpful in the diagnosis and detection of ARVC. The most common manifestations were abnormal structure and function of the right ventricle and abnormal ECG of repolarization and ventricular arrhythmia which originates from the right ventricle.