Fluoropyrimidine chemotherapy in a rat model: comparison of fluorouracil metabolite profiles determined by high-field 19F-NMR spectroscopy of tissues ex vivo with therapy response and toxicity for locoregional vs systemic infusion protocols

A Sprague-Dawley rat model with DS sarcoma transplanted in the thigh was used to compare transcatheter locoregional i.a. and systemic i.v. administration of 5-fluorouracil (FU) at 12 dose-rate schedules: 25, 50 and 100 mg/kg; bolus, 1, 5 and 24 h infusions. In experiment A tumor (62/67 animals) as well as liver and kidney (56/67 animals) were excised 1 h after a single bolus or 1 h infusion or at the end of 5 and 24 h infusions. (19)F-NMR spectroscopy at 11.7 T was used to quantitate FU and its metabolites in ca. 1 g of tissue at 4 degrees C. In experiment B analogous FU treatments were repeated for 5 days (rats 80+11 controls). Tumor volumes vs time, various blood parameters and survival times were recorded, and a log growth rate parameter log GR, a response index RI, and a toxicity index TI were calculated. The i.a. vs i.v. ratios for tumor concentrations of FU and total anabolites (F-Nucl) were >1 for nearly all treatments and increased with infusion time at the higher doses. F-Nucl in tumor correlated linearly with total fluorine concentration (Tot. F range 30-1100 nmol/g) over all treatments (r=0.92, slope=0.45, p<0.0001). For non-bolus i.v. treatments [FU+F-Nucl] decreased linearly with decreasing FU dose rate (r(2)=0.74, zero intercept), while i.a. treatments showed non-linear behavior. For non-bolus treatments the mean log GR per treatment group showed a negative correlation (r=-0.87) with log[F-Nucl]. The most effective non-toxic treatments were 25 mg/kg over 5 or 24 h; the i.a. route was superior to i.v. on the basis of [FU+F-Nucl], RI, the reduction in log GR, and Kaplan-Meier survival statistics. For liver and kidney Tot. F (>83% FU catabolites) reached ca. 3-4 and 6-7 micromol/g, respectively, at the highest dose rates for either route; F-Nucl were detected only for Tot. F>500 nmol/g and increased exponentially as Tot. F increased (toxic treatments). The concentrations of the main catabolite (alpha-fluoro-beta-alanine, FBAL) in tumor did not correlate with Tot. F but rather with FBAL levels in kidney (r=0.90, all treatments), indicating that uptake of liver-derived FBAL from the circulation is the major source of FBAL in tumor.     

A tctex1-Ca2+ channel complex for selective surface expression of Ca2+ channels in neurons

Voltage-gated Ca(2+) channels (VGCCs) are important in regulating a variety of cellular functions in neurons. It remains poorly understood how VGCCs with different functions are sorted within neurons. Here we show that the t-complex testis-expressed 1 (tctex1) protein, a light-chain subunit of the dynein motor complex, interacts directly and selectively with N- and P/Q-type Ca(2+) channels, but not L-type Ca(2+) channels. The interaction is insensitive to Ca(2+). Overexpression in hippocampal neurons of a channel fragment containing the binding domain for tctex1 significantly decreases the surface expression of endogenous N- and P/Q-type Ca(2+) channels but not L-type Ca(2+) channels, as determined by immunostaining. Furthermore, disruption of the tctex1-Ca(2+) channel interaction significantly reduces the Ca(2+) current density in hippocampal neurons. These results underscore the importance of the specific tctex1-channel interaction in determining sorting and trafficking of neuronal Ca(2+) channels with different functionalities.     

Ligand interactions by activating and inhibitory Ly-49 receptors

Summary: Natural killer (NK) cells express families of homologous receptors, members of which either activate or inhibit NK cells. We demonstrate that mouse Ly-49D is an activating receptor for the MHC antigen H2-D^d, which is also a ligand for the related inhibitory receptor Ly-49A. To compare and contrast their interactions with class I MHC ligand, we studied each of these receptors expressed in a rat NK-cell line, RNK-16, for their capacity to recognize wild-type or mutated H2-D^d. Our studies with Ly-49A reveal that functional interaction with H2-D^d depends on residues in the floor of the H2-D^d peptide-binding groove. The recent co-crystal of Ly-49A with H2-D^d indicates that these are not contact residues, thus they may contribute to allelic specificity through conformational changes in H2-D^d. We found that structural requirements for functional recognition of H2-D^d by Ly-49D differ markedly from those for recognition by Ly-49A. We note that H2-D^d expression on certain target cells is not sufficient to activate lysis mediated by Ly-49D, though the additional requirements for functional interaction are not yet identified. Here we review recent studies of Ly-49 receptor ligand specificities and their molecular basis. The functions of these related receptors with opposing functions and shared allospecificity remains unclear.
This work was supported by the Veterans Administration. M.C.N. is also supported by the Arthritis Foundation and the American Cancer Society. W.E.S. received NIH grant RO1 CA69299. We thank J.C. Ryan for communication of unpublished results. We thank H. Houtkooper and T. Ferrin for the molecular graphics image in Fig. 3 , which was created with the MidasPlus modeling system, supported by the NIH grant P41-RR-01081.     

Cellulose acetate electrophoresis of creatine phosphokinase isoenzymes in the diagnosis of myocardial infarction.

A method for rapid separation and visualization of creatine phosphokinase (EC 2.7.3.2 ATP: creatine phosphotransferase) isoenzymes on cellulose acetate has been developed. The technic uses the Beckman microzone electrophoresis system, and is applicable to other cellulose acetate systems. Incubation is with a commercially available substrate solution, and the isoenzyme bands are visualized by fluorescence using a long-wavelength ultraviolet light. An intermediate migrating isoenzyme band (CPK-MB) was detected in sera of 67 of 68 patients with myocardial infarction, and was not present in patients with other disorders that might clinically be confused with myocardial infarction.     

Asthma associated with exercise

Exercise is a potent stimulus to asthma. The diagnosis is not always straightforward, and health care providers should have a high index of suspicion. Treatment usually controls exercise-induced asthma but usually requires therapy tailored for each individual patient.     

Role of the left interventricular sulcus in formation of the interventricular septum and crista supraventricularis in normal human cardiogenesis

Serial sections of normal human embryos were studied and three-dimensional images reconstructed to determine the early development of the interventricular septum. The position of the interventricular septum is determined in stage 9 of normal development by the formation of the left interventricular sulcus. As a result of unknown properties of the cells of the myocardial layer, the left interventricular sulcus persists while the right disappears, producing the initial lateral asymmetry of the primary heart tube. By stage 14, the left interventricular sulcus forms a spiral which is continuous with the developing interventricular septum. The dorsal limb of the spiral passes to the right between the atrioventricular canal and the origin of the outflow tract, and is lost in the wall of the trabeculated right ventricle. It appears that this dorsal limb of the spiral is the precursor of part of the cirsta supraventricularis. The midportion of the sulcus, the bulboventricular groove, becomes the socalled fibrous continuity between the aortic and mitral valves. The ventral limb of the spiral passes caudally in the anterior interventricular groove and then dorsally and cranially toward the dorsal cushion of the atrioventricular canal. The ventral limb of the spiral is continuous with the crest of the muscular interventricular septum, which develops by apposition of tissue from the expanding right and left ventricles. From stage 14 to stage 19, the muscular interventricular septum, the atrioventricular endocardial cushions, and the ventricular end of the spiral ridges of the outflow tract appose and fuse. Subsequent formation of the membranous interventricular septum completes the physical separation of the right and left ventricles.     

Skin Conductance Response Conditioning with High CS Intensities: Additional Evidence with New Controls

In an effort to determine whether or not conditioning is possible when CS intensity is at least as high as US intensity, nine groups of human subjects were employed in a skin conductance conditioning study. White noise CS and US intensities of 95- and 115-dB were varied orthogonally in the experimental groups, while control groups were incorporated to control for overall signal frequency and differences in habituation rates attributable to differences in intertrial interval. By conventional contrasts first interval response (FIR) conditioning was observed, but when controls for differential habituation rates were incorporated in the contrasts there was no evidence of FIR conditioning. Second interval response (SIR) conditioning was obtained, but it was manifest as an anticipatory response to the higher of two US intensities rather than in conventional conditioning vs control group comparisons. It was also shown that high CS intensities induce suppression of SIR levels, with greater suppression associated with the higher intensity. Several conclusions were made: 1) in a simple trace conditioning paradigm with skin conductance responding as the measure, it is not clear that what we have typically called a conditioning effect is separable from an habituation effect; 2) conditioning is possible even when CS intensity is as high as or higher than US intensity; and 3) the use of time sample measurement in the absence of signals provides a useful baseline for determining overall increases and decreases in SIR level.     

Epstein-Barr virus-associated smooth muscle tumor in patients with acquired immunodeficiency syndrome.

Epstein-Barr virus (EBV)-associated smooth muscle tumor (SMT) is a recognized but uncommon disease that is found to occur in patients with immunocompromised conditions such as acquired immunodeficiency syndrome (AIDS). These tumors may be multifocal and located at unusual sites, such as the brain and liver. This report describes the case of 2 AIDS patients with EBV-associated SMT and highlights the features and outcome of this rare but potentially important tumor in human immunodeficiency virus management.