Thermal and electrical characteristics of thermal dilution cardiac catheter systems.

A combination of cooling systems for the injectate used in thermal dilution cardiac output measurements is shown to quickly cool the thermal indicator to a low homogeneous temperature. The variability of the physical constants characterizing the catheter thermistors are found to be adequately compensated for by the calibration resistors incorporated in the catheters. The calibration resistors are found to have a magnitude approximately 20 times the differential resistivity of the thermistors and this linear relationship is validated on theoretical grounds.


Application of neural networks in medical diagnosis: the case of sexually-transmitted diseases.

In this paper neural networks are used to formulate a means of diagnosing sexually-transmitted diseases (STD's). An overview of the theoretical background of neural networks is presented. A summary of the diseases used in the project and their signs and symptoms are given. These signs and symptoms are used to train a network. Upon presentation of a set of signs and symptoms to the trained network, the presence of a disease or diseases with those symptoms may be deduced.


Computational fluid mechanical evaluation of steady-flow energy losses in cardiac valve prostheses.

A form of the general integral energy conservation equation is applied to the case of steady flow through a rigid control volume bounded by stationary walls and fixed inflow and outflow control surfaces. The total energy loss due to viscous dissipation in the control volume is then defined as the change in mean (pressure + kinetic energy + shear stress energy) quantities between the inflow and outflow surfaces. Computational fluid mechanical modelling can then be used to provide the extensive flow field data necessary to calculate the integral means of the total energy components--not only at the inflow/outflow surfaces, but throughout the control volume via a series of "cutting surfaces" progressing from the inlet to the outlet. This allows interchanges between the various forms of energy to be examined and provides an insight into the mechanisms responsible for these interchanges. Two illustrative examples are presented: laminar flow through a specially designed ball-occluded conduit valve in a long conduit run, and through a caged-ball annulus valve mounted in a ventricle-aorta model. Analysis of the results suggests that a new energy loss parameter be defined--a "valve only" loss, calculated by subtracting the total energy loss for the system with the valve absent, from the total energy loss for the same system with the valve in place. This developed concept of "valve only" energy loss has the potential of standardising the findings of different research groups by removing the arbitrary selection of measurement points from reported results.


Response of air, silicon and dosimetric films to x-ray spectra of various qualities.

Calculations have been performed of the kerma to radiographic film and to silicon from a number of x-ray spectra generated at 30 to 140 kV with tungsten and molybdenum targets. These results have been compared with the air-kerma values due to the same beams. It is concluded that both film and silicon can be used as practical dosemeters with an accuracy of +/- 5 to 15%, provided that correction factors are applied based on the generating potential or preferably the beam quality, expressed as half-value thickness.


The use of parallel plate ion chambers to determine surface dose of a 6 MV photon beam.

The shape of the measured photon build-up curve and the surface dose are strongly dependent on the chamber geometry and side wall density. This study examines the response at the phantom surface to a 6 MV beam for the NACP and MARKUS chambers and also for the recently available commercialized ATTIX chamber; and checks the consistency of a published correction term applied to these chambers by comparison of the corrected data sets. The MARKUS and ATTIX chamber results of surface dose versus field size agree to within less than 0.5% over the field size range, whereas the NACP results show an average discrepancy of 22.1% (absolute percentage points), although the slope of the dose versus field size plot is very similar for all three chambers. It is confirmed then that the NACP electron chamber is not optimal for photon dosimetry at an air-tissue interface, and that the chamber of choice from fabrication material and geometrical considerations is the ATTIX solid water chamber.


The stilbene disulfonic acid DIDS stimulates the production of TNF-alpha in human lymphocytes.

Exposure of human peripheral blood mononuclear cells (PBMC) to the stilbene derivative DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) (60 microM and above) significantly increased the release of tumor necrosis factor-alpha (TNF-alpha), as determined by TNF-alpha activity in the incubation media. When the TNF-alpha message was analyzed in PBMC by a reverse transcription/polymerase chain reaction (RT/PCR)-based procedure, it was found that incubation with DIDS (60 microM) was followed by a time-dependent accumulation of TNF-alpha mRNA. Measurements of intracellular pH showed that the presence of increasing concentrations of DIDS resulted in a progressive intracellular alkalinization of PBMC. It is suggested that the known DIDS effect of inhibiting transmembrane anion exchange, i.e., chloride/bicarbonate exchange, might play a role in the stimulation of TNF-alpha production by PBMC exposed to DIDS.


A computer model of glycosylated human butyrylcholinesterase.

The three-dimensional structure of human serum butyrylcholinesterase (BuChE) was modeled using a computer-based amino acid replacement strategy and the known coordinates of crystallized acetylcholinesterase (AChE) from Torpedo californica. The BuChE model was then energetically minimized with dynamic iterations of an adopted basis Newton-Raphson algorithm and the program CHARMM. Hypothetical glycosylation of this structure based upon the known carbohydrate composition of the enzyme was also performed. The glycosylated, minimized model predicts that the tertiary structure of BuChE could be very similar to AChE but that the entrance of the narrow channel leading toward its active site triad probably differs. All nine of the known N-linked oligosaccharides of BuChE are predicted to occur away from the putative active site channel and most are located on one face of the monomer.


A tryptophan-substituted member of the AKH/RPCH family isolated from a stick insect corpus cardiacum.

A neuropeptide, Cam-HrTH-I, has been isolated from the corpus cardiacum of the Indian stick insect Carausius morosus. The peptide causes hyperlipaemia in Locusta migratoria and hypertrehalosaemia in Periplaneta americana and is related to the previously isolated Cam-HrTH-II (pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) by substitution, apparently by a hexose, on the Trp residue. This appears to be the first example of such substitution on a Trp residue.


Calcyclin and calvasculin exist in human platelets.

Using Ca(2+)-dependent affinity chromatography on a synthetic compound (W-7)-coupled Sepharose column, three distinct Ca(2+)-binding proteins have been identified in human platelets. The molecular mass of these three distinct proteins was estimated to be 10, 10.5, 17 kDa, respectively, by polyacrylamide gel electrophoresis in the presence of SDS. The partial amino acid sequence revealed these proteins have EF-hand structures and high homology to the predicted proteins, calcyclin, calvasculin, and calmodulin. Calcyclin and calvasculin have been considered as probably having roles in the control of cell proliferation, but the existence of these two proteins in platelets suggests that they have other intracellular functions related to the Ca(2+)-signal transduction system.


Functional and morphological changes in cultured neurons of rat cerebral cortex induced by long-term application of aluminum.

Aluminum is an environmental neurotoxin and a suspected risk factor for Alzheimer's disease. The neurotoxicity of aluminum on cultured neurons of rat cerebral cortex was investigated using an assay system for synapse formation and immunohistochemistry. The frequency of spontaneous oscillations of intracellular Ca2+, which is correlated to the number of synapses, was decreased after exposure to 100 microM of aluminum chloride for 22 days. Long-term application of aluminum (48 days) caused aggregation of cell bodies and fasciculation of processes. Processes and cell bodies were strongly stained by antibody to tau protein, which is one of the main components of Alzheimer's neurofibrillary tangles. It is suggested that the characteristics of the degeneration of cultured neurons induced by aluminum show some similarities to the pathology observed in brains with Alzheimer's disease.


Hepatocyte growth factor is linked by O-glycosylated oligosaccharide on the alpha chain.

The glycosylation site and the structure of O-glycosylated oligosaccharide of recombinant human HGF were investigated. N-acetylgalactosamine (GalNAc) in the alpha chain suggested the presence of O-glycosylated oligosaccharide. Sugar analysis and amino acid sequence analysis of peptide fragments produced by limited degradation revealed that O-glycosylated oligosaccharide linked to Thr445 of the alpha chain. The molecular weight of the oligosaccharide was determined with ion spray mass spectrometry. From these studies, the structure of the O-glycosylated oligosaccharide on the alpha chain of HGF was concluded as [formula: see text].


A murine sequence-specific DNA binding protein shows extensive local similarities to the amyloid precursor protein.

Microinjection experiments suggested previously that protein binding to the DNA nucleotide sequence GTCACATG, identical to the CDEI element of the yeast centromere, plays an important role in the early development of the mouse. We established from a series of overlapping mouse cDNA clones the sequence of a candidate CDEI-binding protein. Synthesis in Escherichia coli of a fusion protein which binds specifically the CDEI box in vitro confirmed its identification. On the other hand, the translated 511 amino acid sequence shows two regions with high degrees of similarity to the protein precursor (APP) of the beta-protein (amyloid) that accumulates in the brain and blood vessels of Alzheimer patients. A continuous stretch of 195 amino acids includes 133 residues identical to part of the extracellular domain of APP, and 48 of the 70 C-terminal residues of the open reading frame are identical to the APP transmembrane and cytoplasmic domains.


11-hydroperoxyeicosatetraenoic acid is the major dioxygenation product of lipoxygenase isolated from hairy root cultures of Solanum tuberosum.

The profile of primary dioxygenation products of arachidonic acid catalyzed by lipoxygenase isolated from hairy root cultures of Solanum tuberosum treated with a fungal elicitor was compared to that obtained for the enzyme from potato tubers. 11-Hydroperoxyeicosatetraenoic acid (11-HPETE) was the most abundant dioxygenation product formed followed by 8- and 5-HPETEs in the decreasing order of abundance. In contrast, 5-HPETE is the predominant oxidation product of lipoxygenase from potato tubers. Differences in the defense requirements of storage tuber as compared to roots may be the basis of the differences in regio-specificity demonstrated in this work.


Selenouracil derivatives are potent inhibitors of the selenoenzyme type I iodothyronine deiodinase.

Type I iodothyronine deiodinase (ID-I) is a selenoenzyme, which is important for the conversion of the prohormone thyroxine (T4) to the bioactive thyroid hormone 3,3',5-triiodothyronine (T3). 2-Thiouracil derivatives inhibit ID-I by interaction with an enzyme form generated during catalysis. We have now tested the potential inhibitory effects of the selenocompounds 6-methyl- (MSU) and 6-propyl-2-selenouracil (PSU) in comparison with their thioanalogs 6-methyl- (MTU) and 6-propyl-2-thiouracil (PTU) on rat liver ID-I activity using 3,3',5-triiodothyronine (reverse T3, rT3) as substrate and dithiothreitol (DTT) as cofactor. All compounds showed dose-dependent inhibition of ID-I with IC50 values of 1, 0.5, 0.4 and 0.2 microM for MTU, MSU, PTU and PSU, respectively. Our results further suggest that these inhibitions are uncompetitive with substrate and competitive with cofactor. The high potency of selenouracils may be due to reaction with a substrate-induced enzyme selenenyl iodide intermediate under formation of a stable enzyme-selenouracil diselenide.


Proteolytic cleavages of proalbumin and complement Pro-C3 in vitro by a truncated soluble form of furin, a mammalian homologue of the yeast Kex2 protease.

We have recently purified and characterized a truncated soluble form of furin from which the predicted transmembrane domain and cytoplasmic tail were deleted (Hatsuzawa, K., Nagahama, M., Takahashi, S., Takada, K., Murakami, K., and Nakayama, K. (1992) J. Biol. Chem. 267, 16094-16099). Our results showed that furin resembles the yeast Kex2 protease with respect to both its enzymic properties and substrate specificity. Here we demonstrate that the soluble form of furin is capable of converting the precursors of albumin and the third component of complement (proalbumin and pro-C3, respectively) in vitro to mature proteins. Thus furin mimics the Ca(2+)-dependent proalbumin and pro-C3 convertases found in the Golgi membranes (Brennan, S. O., and Peach, R. J. (1988) FEBS Lett. 229, 167-170; Oda, K. (1992) J. Biol. Chem. 267, 17465-17471). Furthermore we show that the variant alpha 1-antitrypsin Pittsburgh, which is a specific inhibitor of the Golgi proalbumin convertase, inhibits not only the Golgi pro-C3 convertase, but also the soluble furin. These results suggest a role for furin in the cleavage of proproteins transported via the constitutive pathway.


Precursor and deaminated forms of both luteinizing hormone-releasing hormone (LHRH) and (hydroxyproline9)LHRH are present in the rat hypothalamus.

A naturally occurring analog of the decapeptide luteinizing hormone-releasing hormone ([Hyp9]LHRH) has been described previously in the hypothalamus of several mammals. It derives from post-translational hydroxylation of the LHRH proline9 residue. In the present work, intermediate LHRH precursors exhibiting both Pro9 or Hyp9 residues in the LHRH sequence were characterized in the rat hypothalamus. Hydroxylation of the Pro9 residue can thus be assumed to occur at an early stage of post-translational maturation. Deaminated, free acid forms of both native decapeptides were also detected. They correspond most likely to catabolites from incompletely processed precursors.


Immunochemical studies of pancreatic colipase-lipase interaction employing immobilized synthetic peptides.

In view to study the possible participation of the sequence portions of colipase including or close to the free carboxyl groups at positions 15 and/or 72 to the binding with pancreatic lipase, we have used three synthetic peptides matching portions 8-16, 59-67 and 67-72 of the amino acid sequence. Polyclonal rabbit anticolipase immune serum, which cross-reacts with peptides in ELISA, was fractionated on columns of peptide coupled to Sepharose. Of the three fractions of antibodies, only that interacting with peptide 8-16 had the capacity to inhibit colipase-dependent lipase activity by specifically preventing the association of lipase with its protein cofactor previously bound to lipid. We conclude that the region spanning residues 8-16 of colipase is of importance for colipase-lipase interaction in the active complex formed at interface.


A major lienal phosphotyrosine phosphatase is inhibited by phospholipids and inositol trisphosphate.

A major "non-receptor" phosphotyrosine-specific protein phosphatase isolated from the 30,000g pellet fraction of porcine spleen is related to the human T-cell tyrosine phosphatase (Cool et al. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 5257-5261) and is strongly inhibited by micromolar concentrations of phosphatidyl inositol (IC50 6 microM) and phosphatidyl serine (IC50 3.7 microM). In addition, the enzyme is inhibited by myo-inositol 1,4,5-trisphosphate (IC50 ca. 2 microM) in a non-competitive manner but not by myo-inositol hexaphosphate. Since the overall cellular tyrosine phosphatase activity greatly exceeds tyrosine kinase activity, inhibition of the phosphatase may be of importance for the regulation of the extent of tyrosine phosphorylation of cellular proteins.


Kinetics and organ distribution of [14C]-sialic acid-GM3 and [3H]-sphingosine-GM1 after intravenous injection in rats.

Serum kinetics and organ distribution of [14C]-sialic acid-GM3 and [3H]-sphingosine-GM1, administered as an intravenous bolus, were analysed in Wistar rats. [3H]-GM1 and [14C]-GM3 had serum half-lives of 1.4 hours and 1.8 hours, respectively. Three hours after injection 75% of the GM1- and 38% of the GM3-associated label were present in the liver. Smaller yet significant amounts of label were present in the central nervous system, kidneys and lung. In vitro studies showed that [14C]-GM3 and [3H]-GM1 incubated with serum were predominantly bound to the High Density Lipoprotein and the Low Density Lipoprotein fractions. These results suggest a rapid serum clearance of exogenous gangliosides by the liver in rats.


Photoaffinity labeling of plasma membrane receptors for aldosterone from human mononuclear leukocytes.

Non-genomic effects of aldosterone on the sodium-proton-antiport have been shown in human mononuclear leukocytes which could be related to a new aldosterone membrane receptor. In the present paper plasma membranes from human mononuclear leukocytes were covalently photolabeled with a [125I]-aldosterone derivative. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed significant aldosterone binding at a molecular weight of approximately 50000 Dalton which was absent with 1 microM cold aldosterone, but not cortisol in the binding media. The presence of the sulfhydryl agent dithiothreitol did not affect results suggesting the absence of disulfide bridges in the steroid binding domain of the receptor. These data are the first to define the molecular weight of the membrane receptor for aldosterone.


Fibronectin receptors are functional on mitotic Chinese hamster ovary cells.

In this paper, evidence is provided indicating that the blockade of presynchronized CHO 15B cells in prometaphase by nocodazole is fully reversible and efficient enough to allow us to analyze the function of the integrin receptors. Flow cytometry analysis using a specific antibody raised against the fibronectin receptor, and binding studies of the radiolabeled fibronectin on the cell membrane, indicated a stable number of receptors at the cell surface during mitosis. Furthermore, in the mean time, only a slight increase in the Kd value of the fibronectin-receptor interaction was detected. A binding assay designed to test the affinity of the receptor for its extracellular ligand in an insoluble form was used. No difference was observed between mitotic and interphasic cells. Taken together, these results indicate that the rounding up of the cells observed during mitosis is not due to a loss of the receptor affinity for its extracellular ligand.


Identification of novel inducible nuclear factors that interact with the acute phase responsive promoter element of rabbit alpha 1-acid glycoprotein gene.

Alpha 1-acid glycoprotein (alpha 1-AGP) is a major acute phase protein that is highly inducible during hepatic acute-phase response. To identify the promoter element(s) required for increased gene transcription under acute condition a 529 bp 5'-flanking region of alpha 1-AGP gene is fused to the chloramphenicol acetyl transferase (CAT) reporter gene and introduced into BNL liver cells. This DNA fragment is capable of inducing synthesis of the reporter gene-product about ten-fold when transfected cells are exposed to conditioned medium from lipopolysaccharide-stimulated peripheral monocytes. Deletion analyses have shown that sequences located between -224 to -22 are capable of eliciting this inducible promoter function. Using electromobility shift assay we have identified two novel inducible nuclear factors from turpentine-induced acute liver that can interact with this regulatory promoter region. Our results indicate that binding of these two factors to the promoter region of alpha 1-AGP gene is highly specific in nature and the induction of this gene under acute condition may involve their participation.


Differential expression of two forms of annexin 3 in human neutrophils and monocytes and along their differentiation.

A variant of annexin 3 (AX3) of apparent mass 36 kD has been detected in human monocytes using a specific immune serum directed against the original 33-kD form of AX3 purified from human placenta. This protein is not a phosphorylated or a glycosylated form of the 33-kD AX3 and its expression increased along monocytic differentiation whereas only the 33-kD AX3 accumulated in neutrophils. This suggests that these two forms of AX3 may play specific roles in these phagocytic cells.


Alterations of protein degradation and 2-D protein pattern in muscle cells of MDX and DMD origin.

Intracellular protein turnover of MDX, DMD and normal muscle was determined by [35S]methionine pulse-chase experiments and subsequent high resolution 2-D gel electrophoresis. In MDX myotubes intracellular degradation of short-lived and long-lived proteins was markedly increased by a factor of 1,4-2,1. In wildtype the rate of degradation of short-lived proteins was approximately 2.6%/h, whereas in MDX these proteins were degraded by 5.7%/h. Long-lived proteins were degraded in wildtype at a rate of 1.8%/h, and in MDX at a rate of 2.5%/h. Furthermore, we have described a 51.000 Da protein with an IEP of 5.1 (p51/5.1), whose net content is highly and specifically reduced in cultured MDX and DMD muscle cells as well as in isolated MDX muscle fibers. Treatment with calcium-channel blockers Dantrolene and Verapamil inhibited the degradation of p51/5.1 in MDX myotubes by more than 90% in contrast to controls.


Acid pH decreases OmpF and OmpC channel size in vivo.

To be effective against gram-negative organisms, beta-lactam antibiotics must be able to penetrate the outer membrane. For Escherichia coli, these compounds generally cross this barrier through non-specific channels in porins OmpF and OmpC. In vitro studies have shown that increased pH induces a switch in the structure of OmpF and OmpC from a small channel conformation to a set of larger-sized channel conformations. In this study, the permeability of two cephalosporins into cells producing either OmpC or OmpF was examined at various pHs. The results suggest that the pH-induced switch in channel size observed in vitro also occurs in vivo.


Calpain may produce a Ca(2+)-independent form of kinase C in long-term potentiation.

Both an enhancement of Ca(2+)-independent kinase activity in the supernatant fraction and enhanced breakdown of type beta kinase C (PKC-beta) were observed in the hippocampus after induction of tetanus-induced long-term potentiation (LTP) in the hippocampal CA1 region of rat. The enhanced activity was inhibited by the PKC-specific inhibitor, PKC19-36. Both phenomena were also observed simultaneously in the in vitro model system in which hippocampal homogenate was treated with CaCl2, and both enhancements were inhibited by the addition of calpain inhibitors, leupeptin and benzyloxycarbonyl-Leu-Met-H. The results suggest that Ca(2+)-independent kinase activity enhanced in the supernatant fraction during LTP derives from the catalytic fragment of PKC-beta released by calpain.


Renaturation of the brain myelin proteins by octyl glucoside detergent.

The secondary structure of myelin proteins undergoes a deep change when the membrane is delipidated and suspended in an aqueous buffer containing phosphate and sulfate anions. However, when increasing concentrations of octyl glucoside are dissolved in this saline medium, proteins recover gradually its native secondary structure, reaching a maximum for a detergent/protein ratio which, in addition, is optimal for maximal membrane solubilization. Larger amounts of detergent, however, reverted the effect. Results are explained in terms of anion-lipid and detergent-lipid interactions. Quantitative estimates on the spectral profiles let us find the optimal detergent-protein stoichiometry for preserving almost completely the native secondary structure of myelin proteins while keeping maximal solubilization. These findings are of great importance for reconstitution experiments designed with the goal of determining the biological functions of myelin proteins.


Physico-chemical modeling of the role of free radicals in photo-dynamic therapy. I. Utilization of quantum yield data of singlet oxygen formation for the study of the interaction between excited photosensitizer and stable free radicals.

The measurement of the relative quantum yield of singlet oxygen formation, a simple process without tedious sample deoxygenation, is shown to furnish data on the interaction of the excited photosensitizer with any additive (in this case stable free radicals) given to the sample. The rate constants derived from such measurements are in good agreement with direct determination of the corresponding values.


Identification of NGF-response element in the rat neuropeptide Y gene and induction of the binding proteins.

Gene expression of the rat neuropeptide Y (NPY) increases by 100 times, as the PC12 cells differentiate into sympathetic neuron-like cells with NGF treatment and this increase is partly due to transcriptional activation of the NPY gene (Sabol and Higuchi, Mol. Endocrinol. 4, 384, 1990). To identify the NGF-response element, a transient expression assay was carried out by using the CAT reporter genes containing various lengths of the 5' upstream region of the NPY gene in the PC12 cells. The 48-base element (-80/-33 upstream of the Cap site) was identified as a NGF-response element (NGFRE). Gel shift assay indicated the existence of at least two DNA-binding proteins to NGFRE. The binding activity of the protein(s) (NDF1) to the upper region (-80/-63) was increased by 3-fold with NGF treatment for 24 h. These findings suggest that these nuclear proteins are involved in the enhanced transcription of the NPY gene by NGF.


31P NMR studies of the ATP/alpha-crystallin complex: functional implications.

Evidence is presented for the binding of ATP to alpha-crystallin in the lens by 31P NMR spectroscopic measurements. The chemical shift data as well as the T1 and T2 values indicate that P beta and P gamma of ATP are of prime importance in binding. In addition, it is demonstrated that the association of alpha-crystallin with purified fiber cell membranes is significantly enhanced by the addition of ATP. These results suggest that ATP modulates the functional behavior of alpha-crystallin.


TSH-induced galactose incorporation at the NH2 terminus of thyroglobulin secreted by FRTL-5 cells.

FRTL-5 cells were cultured in media containing standard growth factors with or without TSH, plus labeled precursors of N-linked oligosaccharide chains. The thyroglobulin secreted in the medium was purified and fragmented with CNBr. Three peptides were identified by NH2-terminal sequencing, that were labeled mainly with D-[2-3H]mannose, independent of TSH. One of them, corresponding to the NH2-terminus of thyroglobulin, incorporated both more D-[2-3H]mannose and more D-[1-3H]galactose upon TSH addition. These data likely reflect a TSH-induced increment of N-linked glycosylation at the NH2-terminus of thyroglobulin, mostly with the maturation of high-mannose to complex chains.


Proteolytic activation of a single-chain precursor of hepatocyte growth factor by extracellular serine-protease.

Hepatocyte growth factor (HGF) is biosynthesized as a single-chain precursor (pro-HGF) and is proteolytically processed to a two-chain mature form. When MRC-5 fibroblasts were pulse-radiolabeled under serum-free conditions, pro-HGF was the predominant molecular form of HGF in the culture medium. CHO cells transfected with an expression plasmid containing a full-size human HGF cDNA produced pro-HGF when these cells were cultured in serum-free medium. These findings suggest that HGF is secreted as a pro-form, which is then converted to a two-chain form by extracellular protease. Single-chain HGF exhibited mitogenic activity on cultured hepatocytes, with a potency similar to that of mature HGF, but this activity was remarkably inhibited by leupeptin. We postulate that inactive pro-HGF is converted to an active two-chain form by a leupeptin-sensitive serine-protease expressed by hepatocytes. Neither plasminogen activators nor plasmin showed any processing activity of pro-HGF in vitro.


Lipoprotein lipase-mediated lipolysis of very low density lipoproteins increases monocyte adhesion to aortic endothelial cells.

Lipoprotein lipase (LPL) bound to vascular endothelial cells hydrolyses triglycerides in plasma lipoproteins. To explore the role of LPL in atherogenesis, the effect of LPL-mediated lipolysis of very low density lipoproteins (VLDL) on monocyte adhesion to endothelial cells was examined. Adhesion of U937 monocytes to porcine aortic endothelial cells that were incubated with VLDL and purified bovine milk LPL was markedly higher than endothelial cells that were incubated with VLDL alone. The increase in monocyte adhesion obtained with VLDL was dependent on the concentration of the lipoprotein, monocyte dose and time of incubation. The increase in adhesion correlated with generation of free fatty acids from the hydrolysis of triglycerides in VLDL by LPL. Furthermore, direct addition of oleic acid to endothelial cells also increased adhesion of monocytes. We postulate that LPL-derived lipolytic products increase monocyte adhesion to vascular endothelium and thereby promote atherogenesis.


Surface activation of pro-cathepsin L.

Pro-cathepsin L is an inactive zymogen that has been shown previously to undergo autolysis at pH 3.0 to give mature forms of the enzyme. We have now been able to demonstrate that this enzyme can undergo activation at pH 5.5 in the presence of negatively charged surfaces. Activation could also be measured at pH 6.0, but no activation occurred at pH 6.5 or higher. The initiation of activation depends upon the presence of a small percentage of active pro-enzyme, and this is then followed by a more rapid activation to give mature forms of the enzyme. No significant intermediate molecular forms of the enzyme were seen. The time taken for processing of the pro-enzyme to single-chain mature enzyme is comparable to that seen in biosynthetic pulse-chase experiments.


N-linked glycosylation of beta-amyloid precursor protein.

The beta-amyloid peptide that accumulates in the brain of patients with Alzheimer's disease is derived by proteolytic processing of a family of membrane bound beta-amyloid precursor proteins (beta APPs). The three major isoforms of beta APP, derived by alternative splicing, contain 695, 751, and 770 amino acids. They are heavily O-glycosylated and contain two N-linked glycosylation sites. The pathways leading to beta-amyloid deposition in brain are not clear. It is possible that defects in metabolic and processing pathways of beta APP lead to the increased production and deposition of beta-amyloid. In many cases post-translational modifications, such as glycosylation, are important in regulating such pathways. We studied N-linked glycosylation of the 695 amino acid form of beta APP in detail by deleting the two potential glycosylation sites at Asn467 and Asn496. The mutants were examined both in a cell-free transcription/translation/glycosylation system and in transfected Chinese hamster ovary (CHO) cells. In both systems, only Asn467 was glycosylated. In CHO cells the N-linked oligosaccharide on beta APP was completely resistant to Endoglycosidase H, suggesting that it is of complex type. These mutants will be useful for studying the role of glycosylation in the metabolism of beta APP.


Transcriptional inhibition of the bacteriophage T7 early promoter region by oligonucleotide triple helix formation.

We have identified a purine-rich triplex binding sequence overlapping a -35 transcriptional early promoter region of the bacteriophage T7. Triplex-forming oligonucleotide designed to bind this target was annealed to T7 templates and introduced into in vitro transcription systems under conditions favoring specific initiation from this promoter. These templates demonstrated significant transcriptional inhibition relative to naked genomic templates and templates mixed with non-triplex-forming oligonucleotide. It is suggested that triplex formation along this target interferes with transcriptional initiation, and this mechanism may hold potential to disrupt bacteriophage T7 early transcription in vivo.


Biosynthesis of sulfated glycoprotein-N-glycans present in recombinant human tissue plasminogen activator.

Recombinant human tissue plasminogen activator expressed in murine epithelial cells carries, in part, sulfated N-glycans, which are characterized by the presence of a NeuAc alpha 3[SO4-6]Gal unit. In order to study the biosynthesis of this novel structural element, corresponding sulfated asialooligosaccharide alditols were resialylated in vitro using a crude sialyltransferase preparation from murine liver which was shown to contain Gal beta 1,3(4)GlcNAc alpha 2,3-sialyltransferase activity. Products were analyzed for transfer of sialic acid residues by anion-exchange HPLC. The results demonstrated that resialylation of SO4-6Gal-residues did not occur. Therefore, it may be concluded that transfer of the sulfate group is the final step in the biosynthesis of this structural epitope.


Phosphorylation-associated conformation shift of anti-oncogene phosphoprotein p53 in concanavalin-A activated human T lymphocytes.

A new radioimmunoassay for p53, employing an anti-peptide antibody directed against conserved Domain V, exhibited specificity for a relatively dephosphorylated form of p53. This form, correlated with the monoclonal antibody PAB421+ conformation, appeared transiently in the cytosol of cycloheximide-treated T cells undergoing activation by concanavalin-A/serum. Concurrently, there were decreased levels of p53 in the nucleus that correlated with increased phosphorylation of p53. After 90 min nuclear levels of p53 increased steadily above levels of unstimulated cells. Anti-p53 antibodies introduced into cells prior to stimulation enhanced cell proliferation in response to mitogens.


Alpha-lipoic acid is a potent inhibitor of NF-kappa B activation in human T cells.

Acquired immunodeficiency syndrome (AIDS) results from infection with a human immunodeficiency virus (HIV). The long terminal repeat (LTR) region of HIV proviral DNA contains binding sites for nuclear factor kappa B (NF-kappa B), and this transcriptional activator appears to regulate HIV activation. Recent findings suggest an involvement of reactive oxygen species (ROS) in signal transduction pathways leading to NF-kappa B activation. The present study was based on reports that antioxidants which eliminate ROS should block the activation of NF-kappa B and subsequently HIV transcription, and thus antioxidants can be used as therapeutic agents for AIDS. Incubation of Jurkat T cells (1 x 10(6) cells/ml) with a natural thiol antioxidant, alpha-lipoic acid, prior to the stimulation of cells was found to inhibit NF-kappa B activation induced by tumor necrosis factor-alpha (25 ng/ml) or by phorbol 12-myristate 13-acetate (50 ng/ml). The inhibitory action of alpha-lipoic acid was found to be very potent as only 4 mM was needed for a complete inhibition, whereas 20 mM was required for N-acetylcysteine. These results indicate that alpha-lipoic acid may be effective in AIDS therapeutics.


Structural organization of the mouse lactoferrin gene.

The complete structure of the mouse lactoferrin gene is presented. Mouse lactoferrin (mLF) is encoded by a single copy gene of approximately 30 kilobases (kb) in size. The gene is organized into 17 exons separated by 16 introns. The exons range in size from 48 base pairs (bp) to 190 bp whereas the introns range from 0.2 kb to 4.3 kb. Structural analysis of the mouse lactoferrin gene reveals that this gene shares a similar intron-exon distribution pattern with both human transferrin and chicken ovotransferrin.


IFN-gamma induces a phospholipase D dependent triphasic activation of protein kinase C in endothelial cells.

The IFN-gamma linked PKC activation in endothelial cells was analysed. It was shown that IFN-gamma activates PKC in three transient and separate cycles within the first 60 minutes after IFN-gamma stimulation. Before each PKC activation there was an increase in DAG level. IP3, phosphocholine and choline productions were measured to determine the origin of DAG. Neither of the PLC products, IP3 or phosphocholine, were released after IFN-gamma stimulation. On the other hand the PLD products choline and PA were released before all the three activation cycles of PKC.


Evidence for the presence and location of annexins in human platelets.

In this study the identity of annexins in human platelets has been determined together with their ability to be released by agents which induce platelet degranulation. The presence of proteins cross-reacting to antibodies against annexins I and V was detected in human platelets. However, the study provided evidence that these annexins are not located on the surface of the plasma membrane in a Ca++ dependent manner. Moreover, activation of platelets with several agents which induced platelet degranulation did not cause release of annexins I or V as determined by both immunoblotting and ELISA.


A low molecular weight peptide from Allium porum with inhibitory activity on platelet aggregation in vitro.

A peptide factor was isolated from Allium porum with strong inhibitory activity on platelet aggregation induced by collagen or ADP. The peptide was isolated by a series of chromatographic techniques and purified to homogeneity by HPLC on RP C8 column. Its molecular weight, as it was estimated by plasma desorption mass spectrometry, is 1052 Da. Amino acid analysis showed the presence of Phe, Asp, Ser, Thr, Arg and Pro.


Biochemical characterization of density-separated trout erythrocytes.

1. A discontinuous gradient in the region of 45-65% "Percoll" has been utilized for the separation of trout erythrocytes. Three different fractions were obtained. 2. We have evaluated antioxidant enzyme activities and membrane fluidity. The results indicated that catalase and glutathione peroxidase activities increased with the density of the fraction while the membrane fluidity was unchanged. 3. The observed results show a marked difference between nucleated (fish) and unnucleated (human) separated erythrocytes.


Serine proteinase inhibition by the cyclic thiolic compound YS3025: a crystallographic study.

In order to unravel the serine proteinase inhibition mechanism by cyclic thiolic compounds, the X-ray crystal structure of bovine alpha-chymotrypsin inhibited by 3-[2-(2-thiophencarboxythio)]-propanoyl-4-thioazolidin carboxylic acid (YS3025) has been studied by means of difference Fourier techniques and refined at 2.8 A resolution (R-factor = 0.174). The thiophencarbonyl moiety of YS3025 is covalently linked, in the acyl-enzyme complex, to Ser195 OG atom of bovine alpha-chymotrypsin, and located at the entrance of the proteinase primary specificity subsite (S1). The present data confirm previous hypotheses raised on the inhibition mechanism of serine proteinases, based on solution studies of human leukocyte elastase in the presence of the YS3025 parent compound 2-[3-thiophencarboxythio]-N-[dihydro-2(3H)- thiophenone-3-il]-propionamide (MR889).


GM3 affects carboxyl methylation in the human erythrocyte membrane.

Effects of gangliosides in human erythrocyte membrane using carboxyl methyltransferase have been investigated. As GM3 concentration increased, methylatability for membrane was increased. But bovine brain ganglioside mixture did not alter methylatability even at a higher concentration. When 30 microM of GM3 was used in erythrocyte membrane, methylatability was increased by 32%. When purified-glucose transporters were reconstituted into egg phosphatidylcholine-liposome with GM3, methylatability was increased by 37%. Thus conformational difference of membrane according to localization of GM3 in intact human erythrocyte membrane or liposome possibly increases the methylatability and activity of glucose transporter itself.


Structural analysis of pigeon lens crystallins by near-infrared Fourier transform Raman spectroscopy.

Crystallins from pigeon eye lenses were isolated and purified by gel-permeation and anion-exchange chromatographies and characterized by gel electrophoresis, amino acid analysis and Raman spectroscopy. alpha- and beta-Crystallins could be obtained in relatively pure forms by single-step size-exclusion chromatography whereas an extra step of ion-exchange chromatography was needed for the separation of delta crystallin from the beta-crystallin fraction. In contrast to most characterized vertebrate species, a large amount of glycogen is eluted as a high molecular form in the first peak of gel filtration column. Structural analyses of total crude soluble proteins and purified alpha-, beta- and delta-crystallin fractions were made with respect to their amino acid compositions and characteristic near-IR Fourier-transform Raman spectra. The results indicate that the major secondary structures of alpha- and beta-crystallins are mainly anti-parallel beta-pleated sheet in nature as judged by the Raman signals at 1242 (amide III) and 1669-1670 cm-1 (amide I) whereas delta-crystallin consists of a significant content of alpha-helices as evidenced by the Raman signal at 1657-1660 cm-1 (amide I). The low intensity of S-S disulfide stretching vibration at 508-510 cm-1 coupled with the presence of S-H stretching at 2560-2580 cm-1 for alpha-, beta- and delta-crystallin pointed to the fact that sulfhydryl groups in most crystallins are resistant to air oxidation during the process of homogenization and protein extraction. It is also found that the relative Raman signal intensities of Tyr, Phe, and Trp residues in purified crystallins correlate very well with the data obtained from amino acid analysis. Especially noteworthy is the demonstrated usefulness of applying Raman techniques in the detection of the microenvironments of the aromatic amino acids such as Tyr and Trp in the native crystallins, which may prove useful in the study of contribution of these aromatic residues to crystallin packing and stability.


Determination of the subunit contact region of aspartase.

The subunits of tetrameric enzyme aspartase from Escherichia coli and Pseudomonas fluorescens were incapable of forming hybrid tetramers, suggesting that the subunit contact regions of these two enzymes are not conserved in spite of significant homology between the total sequences of the enzymes. To locate the subunit contact region, we modified cysteine residues of the intermediate species formed during the assembly of the subunits of aspartase from E. coli. Subunits modified with N-ethylmaleimide were unable to assemble into tetramers. Further experiments showed that Cys-88 was the primary residue that was modified. The sequence flanking Cys-88 is quite different from that in the the enzyme from P. fluorescens, suggesting that this region participates in the mutual recognition of subunits.


Effect of concanavalin A on the activity of acid and alkaline phosphatases.

The effect of Concanavalin A on the activity of acid and alkaline phosphatases has been investigated. Both the glycoproteins were inhibited by Con A (about 30-40% with 4 mg final concentration in the reaction mixture of Con A). In case of the acid phosphatase, the addition of 1.0 M NaCl, instead of 0.5 M, stimulated the enzyme activity at low concentrations of Con A. The significance of the lectin effect on the stability of glycoenzymes and its implications in bioseparation and enzyme immobilization is briefly discussed.


Influence of pH and phosphate ions on the kinetics of enolisation and degradation of fructosamines. Studies with the model fructosamine, N epsilon-1-deoxy-D-fructos-1-yl-hippuryl-lysine.

Investigation of the rate of enolisation and degradation of the model peptide fructosamine N epsilon-1-deoxy-D-fructos-1-yl-hippuryl-lysine and related monosaccharides revealed the fructosamine to be activated towards enolisation but little of the enolic intermediates proceeded to form advanced glycation endproducts. For the oxidative degradation of monosaccharides, enolisation was rate-limiting. Enolisation of the fructosamine was promoted by hydroxide, phosphate and pyrophosphate buffer ions but not directly influenced by the protonation state of the fructosyl amino group. The formation of advanced glycation end-products may be greatly enhanced in the presence of suitable catalysts (trace metal ions) of the degradation of fructosamine-derived enolic intermediates.


Simultaneous formation of native ribonuclease and proinsulin from their mixed S-sulfonated derivatives by protein disulfide isomerase.

Although the formation of native disulfide bonds of a protein from randomly linked disulfides by protein disulfide isomerase has been extensively studied, the possibility of simultaneous formation of the native proteins from a mixture has not been examined. It is shown in this paper that native ribonuclease and proinsulin can be nearly quantitatively formed by protein disulfide isomerase from a mixture of their S-sulfonated derivatives independent of the presence of each other.


A sensitive method for the analysis of urinary proteoglycans.

Twelve control persons excreted 282 +/- 106 micrograms proteoglycans/l urine (+/- S.D.) in a random urine sample. For four patients with a clinical proteinuria of 1.1 to 5.8 g/l, the excretion varied between 52 and 387 micrograms/l. The control proteoglycan pattern in an electrophoretic analysis on polyacrylamide gel and stained with digoxigenin followed by incubation with digoxigenin antibodies, consisted of a major band with a molecular weight of 100,000. It comigrated with a similar band in the serum proteoglycan pattern. The control pattern contained also lighter fractions with molecular weights between 50,000 and 28,000. The major proteoglycan band remained unchanged in the pattern of the proteinuric patients while conspicuous new bands appeared in the pattern of patients with proteinuria greater than 1.9 g/l. They seem to be of urinary tract origin as they had no counterparts in the serum proteoglycan pattern.


Induction and regulation of D-xylose catabolizing enzymes in Fusarium oxysporum.

In Fusarium oxysporum DSM 841, the requirement of oxygen was found to be associated with the induction of key D-xylose catabolizing enzymes. NADPH-linked D-xylose reductase and NAD-linked xylitol dehydrogenase. Both enzymes were detected in cell free extracts of F. oxysporum grown in the medium containing D-xylose, L-arabinose and D-galactose as substrate. D-xylose, L-arabinose and D-galactose were also found to be substrates for NADPH-linked activities. However, unlike xylitol, neither L-arabitol nor galactitol supported the NAD-linked reactions, suggesting the diversion of metabolic pathways of L-arabinose and D-galactose from that of D-xylose following formation of pentitol.


Effect of diet-induced obesity on kinetic parameters of amino acid uptake by rat erythrocytes.

The effects of cafeteria diet-induced obesity upon in vitro uptake of L-Alanine, Glycine, L-Lysine, L-Glutamine, L-Glutamic acid, L-Phenylalanine and L-Leucine by isolated rat erythrocytes have been studied. The total Phe and Leu uptakes followed Michaelis-Menten kinetics. The Glu uptake was fitted to diffusion kinetics. The uptakes of Ala, Gly, Lys and Gln were best explained by a two-component transport: one saturable and one diffusion. Obesity increased the Km value for Ala, Gln and Leu, and the Vmax value for Ala, but decreased the Vmax for Lys. Kinetic parameters of Phe uptake were unaffected by obesity. In addition, the pseudo-first order rate constant (Vmax/Km) for Ala, Gly, Gln, Lys and Leu uptake decreased as a result of cafeteria diet-induced obesity. The Kd value for Ala, Gly, Gln and Glu decreased and that of Lys increased as result of obesity. These adaptations could, at least in part, explain alterations in amino acid distribution between blood cells and plasma related to overfeeding or obesity.


Vanadate treatment increases the activity of glycolytic enzymes and raises fructose 2,6-bisphosphate concentration in hearts from diabetic rats.

The present study examined the effect of vanadate on the activity of key enzymes of glycolysis and the level of fructose 2,6-bisphosphate (F-2, 6-P2) in the hearts of diabetic rats. A 20% decrease in the total hexokinase activity and 66% decrease in the type II isoenzyme was found in diabetic rat hearts. Vanadate treatment doubled the activity of type II hexokinase. Pyruvate kinase and phosphofructokinase 1 activity was reduced by 20% in diabetes, vanadate treatment restored the activity of the enzymes to normal. A 43% decrease in the cardiac F-2, 6-P2 level was found in diabetes of four weeks duration. A significant inverse correlation between blood glucose of experimental animals and the level of heart F-2, 6-P2 was observed. Vanadate treatment doubled the amount of F-2, 6-P2 in diabetic rat hearts.


Metabolism of 16 alpha-hydroxytestosterone by cytochrome P-450 in rat liver.

The metabolism of 16 alpha-hydroxytestosterone by cytochrome P-450 system was studied with two different inductions. At least 5 different metabolites with higher polarity were produced from 16 alpha-hydroxytestosterone. MT-B, one of their products, appeared to be specifically increased by 3-methylcholanthrene- and phenobarbital-inducible P-450, respectively. This suggests that monohydroxylated testosterones are further metabolized by the P-450 system and that the reactions are isozyme specific. This can contribute at least in part to the diversity of steroid metabolism by P-450.


Effect of seasonal acclimatization on estrogen-induced vitellogenesis and on the hepatic estrogen receptors in the male carp.

The levels of circulating vitellogenin in the plasma of male carp after induction by estradiol-17 beta was examined in summer- and winter-acclimatized fish. During the warm season male fish exhibited a clear vitellogenic response, whereas the fish adapted to the cold season did not. The evaluation of the hepatic estrogen receptors revealed that although steroid-binding affinity is not affected by seasonal acclimatization, the concentration of estrogen receptors certainly is. This was evidenced in estrogen treated fish. Summer-acclimatized carp featured a concentration of hepatic estrogen receptors 2.5 fold higher than the cold season adapted fish. The results suggest that the failure of estrogen to induce vitellogenesis in cold adapted carp may be due; at least in part, to a deficient up-regulation of hepatic estrogen receptors in the corresponding acclimatized state.


Effect of L-arginine on pancreatic arginase activity and polyamines in alloxan treated rats.

The effect of L-arginine on the arginase activity and polyamine levels was studied in the pancreas of normal and diabetic rats (120 mg/kg alloxan, i.v.). Four groups were formed (10 male adults per group). I-Control-0.154 M NaCl. II-Diabetic-0.154 M NaCl (96 h after alloxan). III-Control plus 10 mM L-arginine IV-Diabetics plus 10 mM L-arginine. Rats were sacrificed 20 min after L-arginine injection. Glucose in serum and dry weight, proteins, arginase activity and polyamines (HPLC) in pancreas were measured. Higher ratio mg protein/mg dry weight and arginase induction was observed for groups III and IV. Putrescine was low as a consequence of diabetes but restored with L-arginine. The concentrations of spermidine and spermine were lower. These results may suggest that arginine is metabolized to putrescine in the pancreas and that polyamines may be utilized in regenerating processes or for recovering the endocrine pancreatic function.


Iron-reducing activity of plasma membranes.

Human placental trophoblast plasma membranes were prepared by differential centrifugation and solubilized in nonionic detergent. Transferrin receptors were isolated from the solubilized membranes by affinity chromatography on diferric transferrin-coupled Sepharose 4B. The trophoblast plasma membrane vesicles demonstrated NADH-ferricyanide oxidoreductive activity. However, NADH-Fe(III) oxidoreductive activity was very weak when Fe(III)-ammonium citrate or diferric transferrin was used as electron acceptor in the presence of bathophenanthroline disulfonate as an indicator of the reaction. After solubilization, only NADH-ferricyanide oxidoreduction was recovered. Affinity chromatography-purified transferrin receptors did not exhibit any measurable oxidoreductase activity. Thus, when these receptors are present in plasma membranes they mediate redox reactions, but biochemically isolated receptors do not mediate such reactions. These observation suggest that transferrin receptors in plasma membranes bind diferric transferrin, and, in an undetermined way, facilitate Fe(III) release so that iron reduction can occur.


Characterization of Mirabilis antiviral protein--a ribosome inactivating protein from Mirabilis jalapa L.

A protein was purified from root tubers of Mirabilis jalapa to homogeneity by ion-exchange chromatography on CM-Sepharose CL-6B and FPLC on Mono-S column. The purified protein was confirmed to be Mirabilis antiviral protein (MAP). However, in addition to its antiviral property, the MAP was demonstrated to possess abortifacient activity in pregnant mice, inhibitory effect on cell-free protein synthesis and antiproliferative effect on tumor cells. As judged from its biological and physiochemical properties, MAP is a type I ribosome-inactivating protein.


Transcriptional regulation of MnSOD by manganese in the liver of manganese-deficient mice and during rat development.

Evidence is reported that liver manganese deficiency, whether artificially produced by the administration of a Mn-deficient diet, or physiologically occurring in the neonatal life, in mice and rats respectively, causes the down-regulation of the manganese-containing superoxide dismutase at (pre)-transcriptional level. These observations, in addition to previous data concerning Mn-deficiency and the low level of expression of MnSOD in Morris hepatomas, strongly support the role played by the metal ion in the control of the MnSOD by a mechanism of gene activation. While the molecular events taking place in such regulation are not yet identified, the involvement of reactive oxygen species (ROS) as second messengers in the activation of specific transcription factors is suggested.


The effect of intra- and intermolecular disulfide bonds after peptide grafting on the properties of yeast alcohol dehydrogenase.

Hydrophilic peptides including cysteine residues were grafted on activated yeast alcohol dehydrogenase. The grafted enzyme preparation was then submitted to oxidation at various concentrations in order to favour the formation of intramolecular or intermolecular disulfide bonds. Intermolecular bonds led to enzyme inactivation. But a rigidification of the enzyme was observed with intramolecular bonds. However, thiol groups also chelated the catalytic and structural zinc atoms, leading to the corresponding enzyme inactivation and thermolability. Formation of intramolecular disulfide bridges after peptide grafting strengthens enzyme conformation and can induce enzyme stabilization, but it has to take into account the possible interference with the naturally occurring cysteine bridges.


Purification and characterization of N-acetyl-beta-D-hexosaminidase in different anatomical regions of the adult rat epididymis.

The purpose of the present study was to purify and kinetically characterize N-acetyl-beta-D-hexosaminidases A and B (EC 3.2.1.52) from the caput, corpus and caudal regions of the adult rat epididymis. The molecular mass of the purified native enzyme was approximately 250,000 and approximately 223,000 daltons for the A and B isozymes, with a subunit molecular mass of approximately 63,000 and approximately 56,000 daltons, as determined by size exclusion chromatography and gel electrophoresis under reducing conditions. The apparent Michaelis-Menten constant and maximum velocity values were 0.60, 1.55 and 0.68 mM and 0.54, 3.20 and 2.30 microM/min./mg protein for the enzyme purified from the caput, corpus and caudal regions, respectively. These values were determined by using p-nitrophenyl-N-acetyl-beta-D-glucosaminide as the substrate. These data suggest that the enzyme may be more active in the corpus region of the epididymis than in the caput and caudal regions.


Characterisation of genes encoding two novel members of the aldo-keto reductase superfamily.

The predicted amino acid sequence of the protein encoded by a cDNA clone isolated from the protozoan haemoparasite Babesia bovis has approximately 22% amino acid identity with the Pichia stipitis xylose reductase. There are similar levels of amino acid identity with other members of the aldo-keto reductase superfamily. The identities include many residues highly conserved in the superfamily. However, the amino acid sequence of the B. bovis protein (AKR1) clearly lies outside the cluster of the previously characterized members of the superfamily. A putative protein encoded by a previously undescribed partially characterized open reading frame at the igrA (increased glyphosate resistance) locus of Pseudomonas sp. strain PG2982 also exhibits similarity to AKR1 and the aldo-keto reductases.


Effects of extremely low-frequency electromagnetic fields on three plasma membrane-associated enzymes in early chicken embryos.

Exposure to a 60 Hz, 4 uT electromagnetic field caused significant changes in levels of 5'nucleotidase (5'NT), acetylcholinesterase (AChE) and alkaline phosphatase (ALP) during early embryonic development in the chicken. Enzyme levels were significantly higher in embryos with various forms of anatomic malformations (abnormal) than in those with no visible abnormal characteristics (normal). The presence of the electromagnetic field was associated with a marked reduction in enzyme activities in abnormal embryos. Overall mean specific activities for 5'NT, AChE and ALP were 12, 57, 67 and 38, 196, 111 nmol/min/mg protein in abnormal-exposed versus abnormal-control embryos, respectively. In normal-exposed versus normal-control embryos, the values were 5, 28, 57 and 10, 29, 58, respectively.


Synthesis and secretion of gastric sulfomucin in the presence of ebrotidine, a new antiulcer agent.

The effect of a new antiulcer agent, ebrotidine, on the synthesis and secretion of gastric sulfomucin was investigated using mucosal segments incubated in the presence of [3H]proline, [3H]glucosamine and [35S]Na2SO4. The drug, while showing no discernible effect on the apomucin synthesis, evoked a dose-dependent increase in mucin glycosylation and sulfation, which at 100 microM ebrotidine, attained its maximum of 2.4 and 2.7-fold stimulation, respectively. The analysis of mucin secretory responses revealed that ebrotidine caused a concentration-dependent enhancement in sulfomucin secretion which attained its maximum increase of 3.3-fold at 100-120 microM ebrotidine. The sulfomucin elaborated in the presence of ebrotidine exhibited a higher content of a large molecular-weight mucus glycoprotein form, the assembly of which is intimately associated with the sulfation event. The results suggest that the ability of ebrotidine to enhance gastric sulfomucin synthesis and secretion may play an important role in the gastroprotective mechanism of action of this agent.


Comparative effect of fasting on acetoacetate and D-3-hydroxybutyrate metabolism in the newborn chick.

The effect of 24 h fasting on ketone body utilization by three extranervous tissues, liver, duodenum and kidney, was studied in two critical ages of neonatal chick: 4 and 9 days. In 4-day-old chick, plasma concentration of 3-hydroxybutyrate increased about 9-fold after 24 h starvation, while in 9-day-old chick this parameter increased about 23-fold in the same conditions. Hepatic lipogenesis from both precursors sharply decreased by fasting. Changes in the lipogenic activity of duodenum were less patent. However, we have found a clear increase in lipogenesis in chick kidney after 24 h starvation. CO2 production from acetoacetate was higher than that found from hydroxybutyrate. No significant differences in the acetoacetate oxidation to CO2 was observed in any tissue assayed after 24 h fasting. 14C incorporation from ketone bodies into amino acids was clearly decreased in kidney from 9-day-old chick by fasting. In liver and duodenum, acetoacetate incorporation into amino acids was higher than that from hydroxybutyrate.


Characterization of trehalase in Rhodotorula rubra.

Trehalase activity in Rhodotorula rubra was found to be bound to the particulate fraction of a cell-free extract in contrast with the soluble trehalase activity of Saccharomyces cerevisiae. The enzyme was strongly repressed by glucose and derepressed during growth on maltose, trehalose and glycerol. This increase in activity was due to a "de novo" synthesis as seen by inhibition with cycloheximide, a mechanism not described for Saccharomyces cerevisiae. Catabolite inactivation by addition of glucose was also demonstrated. This particulate enzyme does not respond to activation by the cAMP-dependent protein kinase.


Coordinate expression of the enzymes of nitric oxide metabolism in Paracoccus denitrificans.

Cellular activities of nitric oxide producing nitrite reductase (NiR) and nitric oxide reductase (NOR) in Paracoccus denitrificans increased in parallel upon anaerobic adaptation of aerobically grown cells. In addition, both activities exhibited comparable dependences on oxygen supply into the growing culture. The results suggest that the maintenance of a sufficiently high NOR/NiR activity ratio plays an important role in preventing nitric oxide accumulation and its toxic effects on the cells during denitrification.


Purification and properties of chitinase from cabbage.

Chitinase has been purified from the extract of cabbage through successive steps of ammonium sulfate fractionation, chromatofocusing and Sephadex G-75 gel filtration. By these steps, the purity of the enzyme increased by 93.3 fold and the recovery of the enzyme activity was 20%. The purified enzyme had an optimal pH of 5.0, an optimal temperature between 40 to 50 degrees C and a Km of 76 microM for hydrolysis of ethylene glycol chitin. The molecular weight of the enzyme determined from filtration through Sephadex G-75 was 30,000 daltons. Heavy metal ions, Hg2+ (0.5 mM) and Ag+(2.5 mM) significantly inhibited the activity of the enzyme. NBSI1 (1.0 mM), DNFB (0.5 mM) and PMSF (0.5 mM) completely inhibited the activity of the enzyme. The enzyme also showed muramidase activity for hydrolysis of Micrococcus lysodeikticus cell wall. The presence of chitinase in cabbage may function as a defense enzyme against potential pathogens.


Relationship between substrate activity and pKa value of phenols on sulfotransferase from Eubacterium A-44.

The relationship between the kinetics of the enzyme activity and the structural features of phenolic donor and of acceptor substrates was investigated with a sulfotransferase from Eubacterium A-44, a human intestinal bacterium. The enzyme catalyzed the transfer of the sulfate group from the sulfate esters of phenol having a lower pKa to phenols having a higher pKa. When the Km values for acceptor substrates were measured at their optimal pH, a linear plot for log10Km versus the pKa with a slope of 0.615 was obtained. In addition, it is considered that the effect of pH on the Km values for the various acceptors is due to ionization of free enzyme. The kinetic behavior of bacterial sulfotransferase differed from that of mammalian phenol sulfotransferase.


Intervention of adriamycin induced free radical damage.

The cumulative cardiotoxicity of Adriamycin (ADR) is a constraint on its pharmacological use. The generation of drug induced oxygen radicals in heart cells lead to cardiac lipid membrane peroxidation. We studied the free radical scavenging potential of two compounds Oleanolic acid (OA) isolated from Eugenia jumbolana and Ursolic acid (UA) isolated from Ocimum sanctum against ADR induced lipid peroxidation both in liver and heart microsomes in vitro. In our attempt in the management of cardiotoxicity, we have identified OA as a strong protector against ADR induced lipid peroxidation and UA as a mild protector. Protection with OA was 49% and 21% in liver and heart microsomes respectively. On combined treatment, it increased to 69%. UA showed only 13% and 17% protection in liver and heart microsomes. Two methods for the microsome preparation, Calcium aggregation (CA) and Differential centrifugation (DC) were also compared. CA seems to give a better microsomal preparation though the protection was about the same.


Monitoring of haemoglobin-methyl isocyanate adduct by high-performance liquid chromatography with diode array detector.

Carbamylation of haemoglobin by methyl isocyanate (MIC) was detected by high-performance liquid chromatography (HPLC) using a photodiode array detector following cyclisation of the N-terminal valine into methyl isopropyl hydantoin (MIH). MIH was also synthesised by reaction of MIC with valine, the chromatographic conditions standardised and the spectrum derived by a photodiode array detector recorded for confirmation of the identity of MIH. This HPLC method is specific, sensitive and suitable for the detection of exposure of blood samples to methyl isocyanate.


Early history of bioelectromagnetics.

The early history of bioelectromagnetics is reviewed as I experienced it. The period of time chosen extends from my joining the Institute for Physical Foundations of Medicine in Frankfurt in 1937 to the early 1970s, when I retired from the chair of my department at the University of Pennsylvania. Several themes emerge from these recollections. First, clinical and biological work led almost immediately to a heated controversy about the role of athermal vs. thermal effects; this issue has never been settled to the satisfaction of most. Second, good quantitative work on electrical properties and dosimetry began early, well before World War II; its impact on future developments was significant.


Long-term, low-level microwave irradiation of rats.

Our goal was to investigate effects of long-term exposure to pulsed microwave radiation. The major emphasis was to expose a large sample of experimental animals throughout their lifetimes and to monitor them for effects on general health and longevity. An exposure facility was developed that enabled 200 rats to be maintained under specific-pathogen-free (SPF) conditions while housed individually in circularly-polarized waveguides. The exposure facility consisted of two rooms, each containing 50 active waveguides and 50 waveguides for sham (control) exposures. The experimental rats were exposed to 2,450-MHz pulsed microwaves at 800 pps with a 10-microseconds pulse width. The pulsed microwaves were square-wave modulated at 8-Hz. Whole body calorimetry, thermographic analysis, and power-meter analysis indicated that microwaves delivered at 0.144 W to each exposure waveguide resulted in an average specific absorption rate (SAR) that ranged from 0.4 W/kg for a 200-g rat to 0.15 W/kg for an 800-g rat. Two hundred male, Sprague-Dawley rats were assigned in equal numbers to radiation-exposure and sham-exposure conditions. Exposure began at 8 weeks of age and continued daily, 21.5 h/day, for 25 months. Animals were bled at regular intervals and blood samples were analyzed for serum chemistries, hematological values, protein electrophoretic patterns, thyroxine, and plasma corticosterone levels. In addition to daily measures of body mass, food and water consumption by all animals, O2 consumption and CO2 production were periodically measured in a sub-sample (N = 18) of each group. Activity was assessed in an open-field apparatus at regular intervals throughout the study. After 13 months, 10 rats from each group were euthanatized to test for immunological competence and to permit whole-body analysis, as well as gross and histopathological examinations. At the end of 25 months, the survivors (11 sham-exposed and 12 radiation-exposed rats) were euthanatized for similar analyses. The other 157 animals were examined histopathologically when they died spontaneously or were terminated in extremis.


Physiological interaction processes and radio-frequency energy absorption.

Because exposure to microwave fields at the resonant frequency may generate heat deep in the body, hyperthermia may result. This problem has been examined in an animal model to determine both the thresholds for response change and the steady-state thermoregulatory compensation for body heating during exposure at resonant (450 MHz) and supra-resonant (2,450 MHz) frequencies. Adult male squirrel monkeys, held in the far field of an antenna within an anechoic chamber, were exposed (10 min or 90 min) to either 450-MHz or 2,450-MHz CW fields (E polarization) in cool environments. Whole-body SARs ranged from 0-6 W/kg (450 MHz) and 0-9 W/kg (2,450 MHz). Colonic and several skin temperatures, metabolic heat production, and evaporative heat loss were monitored continuously. During brief RF exposures in the cold, the reduction of metabolic heat production was directly proportional to the SAR, but 2,450-MHz energy was a more efficient stimulus than was the resonant frequency. In the steady state, a regulated increase in deep body temperature accompanied exposure at resonance, not unlike that which occurs during exercise. Detailed analyses of the data indicate that temperature changes in the skin are the primary source of the neural signal for a change in physiological interaction processes during RF exposure in the cold.


Research on the neurological effects of nonionizing radiation at the University of Washington.

This paper reviews research on neurological effects of low-level microwave irradiation, which was performed at the University of Washington, during the decade of the 1980s. We studied in the rat the effects of microwave exposure on the actions of various psychoactive drugs, on the activity of cholinergic systems in the brain, and on the neural mechanisms involved. Our results indicate that endogenous opioids play an important mediating role in some of the neurological effects of microwaves, and that parameters of microwave exposure are important determinants of the outcome of the microwave effects.


Radio-frequency electromagnetic fields associated with cellular-radio cell-site antennas.

Because of a heightened public awareness of issues pertaining to the use of electromagnetic energy, concurrent with a rapid growth of the cellular telephone industry, a study was initiated to characterize the electromagnetic environment associated with typical cell-site antennas. In particular, the radio-frequency electromagnetic (RF) fields in the vicinity of several antenna towers, ranging in height from 46-82 m, were characterized by measurement. In all cases, the antennas were omnidirectional co-linear arrays. The maximal power densities considered representative of public exposure were found to be less than 100 microW/m2 (10 nW/cm2) per radio channel. Comparison of measured values with the corresponding values that were calculated from the free-space transmission formula indicated that the analytical technique is conservative (i.e., overestimates field levels). The measured and corresponding analytical values were found to be well below accepted exposure limits even when extrapolated to simultaneous and continuous operation of the maximal number of transmitters that would be expected to be installed at a cell-site. Additional measurements were made in the near field of the same antenna type in a roof-mounted configuration. At a distance of 0.7 m from the antenna, the maximal power density in the main beam was found to be less than 30 W/m2 (3 mW/cm2) when normalized to sixteen radio channels (the maximal number used on a single antenna) and less than 30 mW/m2 (3 microW/m2) at 70 m. In all cases, the effective radiated power (ERP) by each radio channel was 100 W referenced to a half-wave dipole. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results.


A frequency-dependent finite-difference time-domain formulation for induced current calculations in human beings.

The finite-difference time-domain (FDTD) method has been used to calculate SARs and induced currents involving whole-body or partial-body exposures of models to spatially uniform or nonuniform (far-field or near-field), to sinusoidally varying EM fields, or to transient fields such as those associated with electromagnetic pulses. However, a weakness of the FDTD algorithm is that the dispersion of the tissue's dielectric properties is ignored and frequency-independent properties are assumed. Although this is permissible for continuous-wave or narrow-band irradiation, the results may be highly erroneous for short pulses, in which ultra-wide bandwidths are involved. In some recent publications, procedures are described for one- and two-dimensional problems for media in which the complex permittivity epsilon * (omega) may be described by a single-order Debye relaxation equation or a modified version thereof. These procedures based on a convolution integral describing D(t) in terms of E(t) cannot be extended to human tissues for which multiterm Debye relaxation equations must generally be used. We describe here a new differential-equation approach that can be used for general dispersive media. We illustrate the use of this approach by one- and three-dimensional examples of media for which epsilon * (omega) is given by a multiterm Debye equation, and for an approximate two-thirds muscle-equivalent model of the human body. Based on a single run involving a Gaussian pulse, the frequency-dependent FDTD [(FD)2TD] method allows calculations of SARs and induced currents at various frequencies by taking the Fourier components of the induced E fields. The (FD)2TD method can also be used to calculate coupling of the short (ultra-wideband) pulses to the human body.


Microwave sensing of physiological movement and volume change: a review.

The ability non-invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting-receiving antenna, a set of signal-conditioning and processing devices, and a display unit. They operate at continuous-wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001-1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non-conductive walls.


Microwave radiometry in biomedicine: a reappraisal.

Nearly 20 years ago the first papers appeared on biomedical applications of microwave radiometry, and many other papers have since appeared. Yet, despite its unique capabilities, microwave radiometry has so far received only limited acceptance by the medical community, and little commercial success. The chief reasons, we suggest, are the shallow depth of sensing and the difficulty of extracting imaging information from radiometry signals emitted by electrically heterogeneous media. A secondary factor has been the difficulty of validating many proposed clinical applications for the method--in particular, cancer detection. We suggest that microwave radiometry is a viable method of thermal sensing, but its successful applications are likely to be quite different than those that were originally conceived for the technique.


Evaluation of microwave hyperthermia applicators.

Hyperthermia has been used in conjunction with radiation and chemotherapy for cancer treatment. When using electromagnetic heating, applicators are critical components in contact with or in proximity to patients and can be the determining factor for effective and safe treatment. Tissue absorption of electromagnetic energy is determined by many factors. Three cases are shown to illustrate the complexity of microwave heating: 1) The BSD MA-151 applicator has good center heating on a muscle-only phantom as shown in the operation manual. When fat slabs of 0.25, 0.5, 1, and 2 cm thick were added, two hot spots near the periphery of the applicator were evident on all fat surfaces, exposed at 631 MHz. At 915 MHz, the heating was elongated on the surface of the models with 0.25- and 2-cm fat, and two hot spots were observed on the 0.5- and 1-cm fat surfaces. 2) Heating patterns of the Clini-Therm applicators on a muscle-only phantom, as indicated in the operations guide, are elliptical with their major axes perpendicular to the electric field. However, when a bolus is used, the elliptical pattern is parallel to the E field. 3) Heating patterns in cylindrical structures were studied with inhomogeneous models of limbs. Arm and thigh models consisting of fat, bone, and muscle material were heated with Clini-Therm L, M, and MS applicators at 915 MHz. In addition to the geometric effect, the results indicated that placing the applicators with E field parallel to the long axis of cylindrical structures can minimize required power, produce less heating of fats and reduce stray radiation. In conclusion, to apply penetrating microwave or other RF fields for tissue heating, one must simulate the clinical exposure conditions as closely as possible to obtain useful heating patterns.


Anesthetic drugs and emergency departments.

Hospital emergency departments were surveyed on their use of N2O, intravenous anesthetics, and neuromuscular blocking drugs; patients monitoring during their use; and the monitoring and evaluation of the quality and appropriateness of the use of these drugs. We received 90 of the 170 surveys sent for a response rate of 53%. Sixty-three percent of the emergency departments that answered our survey administer one or more of these drugs in the emergency room. Less than two-thirds of these respondents indicated they use patient monitors while administering these drugs. The emergency department monitors and evaluates the appropriate use of these drugs in about half of the hospitals that use them, whereas the anesthesiology department is involved less than 20% of the time. Anesthesiology departments should become more involved in developing criteria for evaluating the quality of anesthesia administered by other hospital departments to help ensure that all patients receive a comparable level of anesthetic care throughout the hospital.


Assessing competency to make a will.

The finding by a court that the author of a will (the testator) lacked mental capacity or was subject to undue influence at the time the will was executed can invalidate the will. A psychiatrist may be asked to assess the competency of a testator when he or she is planning to create or modify a will or after the death of a testator when the will is challenged. To provide guidelines for such evaluations, the authors reviewed the relevant psychiatric, forensic, and legal literature and drew on their own professional experience as well. They outline a systematic approach to the contemporaneous and retrospective evaluation of the elements that affect decisions about mental capacity and undue influence and offer suggestions for the organization and presentation of expert testimony. Awareness of the relevant legal principles and a systematic clinical approach to the assessment can maximize the quality of the psychiatric consultation and expert testimony.


Antinociceptive effects of tizanidine, diazepam and eperisone in isolated spinal cord-tail preparations of newborn rat.

Antinociceptive effects of three centrally acting muscle relaxants, tizanidine, diazepam and eperisone, were studied using an isolated newborn rat spinal cord-tail preparation. Potentials were recorded from a lumbar ventral root (L3-L5) extracellularly using a suction electrode. Pinch stimulation applied to the tail elicited a depolarizing response in the ventral root lasting 15-30 sec, referred to as the tail-pinch potential. Electrical stimulation of the ipsilateral dorsal root of the same segment with a single shock induced depolarizing responses in the ventral root. The responses consisted of monosynaptic and polysynaptic reflexes with a fast time course, followed by a slow depolarizing response lasting about 20 sec. The latter slow response was designated the ipsilateral slow ventral root potential (VRP). Both the tail-pinch potential and the ipsilateral slow VRP were depressed by application to the spinal cord of tizanidine (2-3 microM), diazepam (2 microM) and eperisone (100-200 microM). The effect of tizanidine was reversed by alpha 2-adrenoreceptor antagonists, yohimbine and idazoxan, but not by an alpha 1-antagonist, prazosin. The effect of diazepam was reversed by the benzodiazepine antagonist, flumazenil.


Concomitant administration of recombinant human interleukin-2 and recombinant interferon alfa-2A: an active outpatient regimen in metastatic renal cell carcinoma.

A phase II trial of interleukin-2 (IL-2) and interferon alfa (IFN-alpha) in metastatic renal cell carcinoma (RCCa) was conducted. A lower dosage of IL-2 was given via continuous intravenous (IV) infusion, a route with documented tumor activity associated with less toxicity, with the purpose of improving the therapeutic index of this treatment in an outpatient setting. Thirty patients with metastatic RCCa were treated with the combination of IL-2 and IFN-alpha-2A. IL-2 was administered on days 1 through 4 of each treatment week, as a continuous IV infusion at a dose of 2 x 10(6) U/m2/d. IFN-alpha-2A was administered intramuscularly or subcutaneously on days 1 and 4 of each treatment week, at a dose of 6 x 10(6) U/m2/d. One treatment course included 4 weeks of treatment followed by a 2-week rest. Patients received therapy as outpatients except for the first 4 days of treatment, cycle 1 only. All patients were assessable for toxicity and response assessment. A total of 105 courses of therapy were administered, 51% at full dose. Sixteen patients experienced toxicities resulting in dosage modification. The major treatment-limiting toxicities were gastrointestinal, neurologic, and fatigue. Nine patients (30%) had partial remissions (PRs) with a median duration of responses of 12+ months. The median time to response was 11 weeks. Two partial responders whose sites of metastatic disease were renal fossa and mediastinal lymph nodes (LN), respectively, were found to have achieved a pathologic complete remission (pCR) after surgery. A third patient with a pCR of axillary LN was rendered into a surgical complete remission (sCR) with salvage nephrectomy. Median survival of patients obtaining a PR has not been reached with a median follow-up time of 19+ months. IL-2 and IFN-alpha-2A is well tolerated in the outpatient treatment setting and demonstrates significant clinical activity against RCCa.


Catabolic effect of dexamethasone in the preterm baby.

Most babies treated with dexamethasone for bronchopulmonary dysplasia exhibit an appreciable rise in the blood urea concentration, from a mean of 2.3 mmol/l before steroid to a mean of 7.1 mmol/l after. In order to discover whether this was primarily the result of increased protein catabolism, nitrogen balance studies before and after the start of dexamethasone were performed and a mean deficit in nitrogen retention of 158 mg/kg/24 hours was found. Similarly the urinary 3-methylhistidine (3MH):creatinine ratio before and after the commencement of dexamethasone treatment in a group of preterm babies was measured. It was found that there was a substantial increase in 3MH excretion after dexamethasone: from a mean 3MH:creatinine ratio of 46 in the week before steroids to a mean ratio of 77 in the week after. As 3MH emanates almost exclusively from the breakdown of actin in skeletal muscle cell, this finding implies the loss of muscle tissue. It was also found that the babies were in less positive nitrogen balance after dexamethasone, to a degree which is significant relative to their protein reserves. The long term consequences of a period of increased catabolism are not yet known but the authors suggest caution in the use of dexamethasone, at least in babies with milder degrees of bronchopulmonary dysplasia in whom the ratio of benefit to risk may be less favourable.


Consumer competence and the reform of American health care.

This report examines the role of the expert in the American health care system, both as provider and administrative policymaker. It shows that the guiding assumption of American health care policy, ie, that the medical system can and should be managed by experts on behalf of consumers and patients, does not hold up to scrutiny. It also demonstrates that the important theme in American history of placing authority and responsibility for action in the hands of the individual has not been sufficiently influential in American health care. Drawing on this theme and creating consumer competence and responsibility in health care choices as the keys to health care reform in the United States are advocated.


Loss of 'complexity' and aging. Potential applications of fractals and chaos theory to senescence.

The concept of "complexity," derived from the field of nonlinear dynamics, can be adapted to measure the output of physiologic processes that generate highly variable fluctuations resembling "chaos." We review data suggesting that physiologic aging is associated with a generalized loss of such complexity in the dynamics of healthy organ system function and hypothesize that such loss of complexity leads to an impaired ability to adapt to physiologic stress. This hypothesis is supported by observations showing an age-related loss of complex variability in multiple physiologic processes including cardiovascular control, pulsatile hormone release, and electroencephalographic potentials. If further research supports this hypothesis, measures of complexity based on chaos theory and the related geometric concept of fractals may provide new ways to monitor senescence and test the efficacy of specific interventions to modify the age-related decline in adaptive capacity.


A comparison between preincisional and postincisional lidocaine infiltration and postoperative pain.

We conducted a randomized, double-blind trial to compare the efficacy of preincisional and postincisional wound infiltration with 1% lidocaine (40 mL) on the postoperative pain of 37 patients scheduled for elective inguinal herniotomy. The demand for additional postoperative analgesics occurred earlier in those who received lidocaine infiltration after incision (165 min) than in those who received preincisional lidocaine (225 min, P less than 0.05). The preincisional lidocaine infiltration group also had fewer patients requiring supplemental analgesics (58%) than the postincisional group (94%) (P less than 0.05). We conclude that preincisional infiltration of the surgical wound with lidocaine is a more effective method of providing postoperative analgesia than is postincisional infiltration.


Tampa Bay catheter: a new guiding catheter for endomyocardial biopsy via femoral approach.

Initially, endomyocardial biopsies were obtained almost exclusively using the jugular vein approach. Lately, the femoral vein route has gained popularity and in many centers, including ours, it is preferred. Despite this, guiding catheters specifically designed for endomyocardial biopsy via femoral vein approach are not available. Here, the experience with the Tampa Bay catheter, designed for endomyocardial biopsy using the femoral vein is described. From 1-1-89 to 1-31-90, a total of 486 endomyocardial biopsies were performed in 78 post-heart transplant patients (1-17, mean 6 per patient); 106 were performed via internal jugular vein (22%) and 380 (78%) via femoral vein. Of these, 100 were performed using the Tampa Bay catheter. The remaining 280 biopsies were done using a long sheath or a Judkin's right coronary angioplasty guiding catheter. Biopsy specimens were adequate for diagnosis of rejection in all 106 biopsies performed via internal jugular vein (100%) in 99 of 100 biopsies via femoral vein using the Tampa Bay catheter (99%) and in 274 of the 280 (98%) biopsies using the long sheath or the right Judkin's coronary angioplasty guiding catheter (NS). The femoral vein is larger and easier to find than the internal jugular vein. More important, complications such as right pneumothorax, Horner's syndrome, recurrent laryngeal nerve paralysis, and right phrenic nerve paralysis, known to occur when the internal jugular vein approach is used, can be completely avoided when the femoral vein approach is used.


What is empathy and can it be taught?

Empathy is the "almost magical" emotion that persons or objects arouse in us as projections of our feelings. Empathy requires passion, more so than does equanimity, so long cherished by physicians. Medical students lose some of their empathy as they learn science and detachment, and hospital residents lose the remainder in the weariness of overwork and in the isolation of the intensive care units that modern hospitals have become. Conversations about experiences, discussions of patients and their human stories, more leisure and unstructured contemplation of the humanities help physicians to cherish empathy and to retain their passion. Physicians need rhetoric as much as knowledge, and they need stories as much as journals if they are to be more empathetic than computers.


Radiological aspects of Zenker's diverticulum.

In a retrospective study of 143 patients with Zenker's diverticulum followed for a period of 20 years, we classified the diverticula into 4 categories (A, B, C and D) using Brombart's scheme as a basis; the difference between the first two categories, however, was made on the basis of a morphological-dynamic criterion rather than a purely morphological one. Furthermore, a quantitative index was introduced to define the size of the diverticulum. In two cases we noted a substantial increase in volume with the transition from category C to D after more than 3 years, but we were unable to demonstrate an evolution from category A to B, nor from B to C. Our study confirms, on a large scale, the presence of three possible pathogenetic mechanisms, as proposed earlier in the literature: decreased relaxation of the upper esophageal sphincter as the most frequent factor in all categories except category A, and delayed opening or early closing of this sphincter as less frequent factors. The good relaxation of the upper esophageal sphincter in our category A, the different sex ratio and the absence of evolution in this category suggest that category A does not necessarily evolve further.


Concomitance of psoriasis and atopic dermatitis.

There is a widespread belief that psoriasis (Ps) and atopic dermatitis (AD) are clinically mutually exclusive. A prospective study was undertaken to record the concurrent and/or consecutive coincidence of the two conditions and any shared clinical features. Patients attending a dermatology clinic were systematically examined for the presence of Ps and/or AD. Nine hundred and eighty-three patients were studied--428 with Ps, 224 with AD, 45 with both Ps and AD, and 286 controls. Of AD patients 16.7% had Ps, and 9.5% of Ps patients had AD. In consecutive occurrences, Ps generally followed AD. The ratio of concurrent to consecutive incidences was 3:1. The two diseases are shown not to be mutually exclusive and may coexist in the same individual.


Developmental regulation of insulin in the mammalian central nervous system.

We delineated the ontogeny of rabbit brain insulin concentrations to define the regulatory role of development on this hormone in the central nervous system. Employing a sensitive ELISA, we observed higher concentrations in the late gestation fetal brain (approximately 80-90 ng/g) and early neonatal brain (approximately 195 ng/g) in comparison to the adult (approximately 32 ng/g; P less than 0.01). Further, we characterized this hormone to determine the identity of insulin (or an insulin-like substance) in brain. Employing porcine/bovine or rabbit insulin as standards, we observed that brain insulin mimicked authentic insulin in its migration on SDS-polyacrylamide and native gel electrophoresis, immunogenicity on Western blot analysis, and its elution profile on immunoaffinity column chromatographic, and high performance liquid chromatographic separation. We then examined the developmental effects on circulating and cerebrospinal fluid (CSF) radioimmunoassayable insulin levels. No statistically significant differences (ANOVA) existed through development in either the serum or CSF insulin levels. Employing multiple regression analysis, no correlation was evident between brain and either serum or CSF insulin concentration. A search for insulin mRNA by Northern blot analysis yielded minute amounts of atypical large sized transcripts. We conclude that the insulin peptide in the central nervous system closely resembles (or is identical to) circulating insulin in many properties and that there is a developmental increase in brain insulin concentrations, the maximal peak occuring in the late gestation fetus and early neonate. Insulin concentrations in brain demonstrate no conventional relationship to either the serum or CSF insulin levels, suggesting an additional source of peptide, which contributes beyond that which is available via the circulation. The amounts of insulin present within the central nervous system are minute (difficult to detect) but in the range (10-100 ng) where the hormone can interact with either insulin or insulin-like growth factor I (IGF-I) receptors that are abundantly present on developing brain cells, thereby executing the biological function of the hormone.


Phasic modulation of vestibulospinal neuron activity during fictive locomotion in lampreys.

This study was aimed at characterizing the activity of vestibulospinal neurons recorded intracellularly during fictive locomotion in lampreys. The majority (78%) of identified vestibulospinal neurons showed rhythmic fluctuations of their membrane potential correlated with locomotor discharges recorded in pairs of rostral ventral roots. Of the rhythmically modulated vestibulospinal cells, most (72%) were maximally depolarized during ipsilateral ventral root discharges and showed a minimum during contralateral activity. Other cells (20%) showed an opposite pattern, that is their peak of depolarization occurred during contralateral activity. Finally, a third category of cells (8%) showed a more complex pattern of activity. Two waves of depolarization could occur per locomotor cycle, one during each burst discharge. The pattern of fluctuation recorded in vestibulospinal neurons appears to be related to the side of the spinal cord onto which the cells are projecting.


Diagnostic and therapeutic technology assessment. Radiofrequency catheter ablation of aberrant conducting pathways of the heart.

Radiofrequency catheter ablation has very quickly generated considerable enthusiasm among electrophysiologists because it offers a less invasive alternative to an open surgical procedure and potentially offers an alternative to lifelong drug therapy. Early literature on RF catheter ablation focused on the technical aspects of the procedure. In contrast, the literature of the past several years is dominated by very favorable reports of large series of patients and the experience of individual institutions. The larger series have focused on the treatment of accessory pathways as opposed to AV nodal reentry pathways. The opinions of the DATTA panelists parallel the literature. The panelists considered the technology to be established in terms of its safety and effectiveness as a curative treatment of accessory pathways, and promising in terms of its safety and between promising and established in terms of its effectiveness as a treatment of AV nodal reentrant tachycardias.