Permeability characteristics and probability of lithium transport in the thin limbs of Henle's loop.
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Animals↗
Biomedical subjects
M Imai
Publications and source records attributed to M Imai.
[A case of malignant lymphoma with various ocular manifestations].
A case of malignant lymphoma with a variety of ophthalmological findings was reported. The patient was a 65-year-old man with malignant lymphoma in retro-peritoneum (stage IV). Uveitis with hypopyon and secondary glaucoma appeared in his right eye, optic neuritis in his left eye. We compared clinical observations with histopathological findings and found that glaucoma was due to direct obstruction in the trabecular space by tumor cells and optic neuritis was due to the tumor cell infiltration into optic nerve.
Aged↗
[Clinical evaluation of various methods of myocardial protections during open heart surgery in infants with ventricular septal defect and severe pulmonary hypertension].
The effectiveness of various methods of myocardial protection were evaluated retrospectively in 59 infants less than 12 months of age who underwent open heart surgery for ventricular septal defect with severe pulmonary hypertension. Intermittent aortic clamping and electrically induced ventricular fibrillation (EF) were employed in 13 infants (Group I), and potassium induced cold cardioplegia and topical cardiac cooling (TC) were used in 14 infants (Group II). Six infants in Group II had additional EF after declamping of the aorta (Group II-A) but the rest of Group II infants did not have any EF (Group II-B). Profound hypothermia and circulatory arrest were utilized in 17 infants (Group III). Cold blood cardioplegia with TC were used in 15 infants (Group IV). Moderate hypothermia were used during cardiopulmonary bypass in Group I, II and IV. The operative mortality for Group I was 15% and was 0% for Group II, III and IV. The incidence of spontaneous resumption of cardiac beat following declamping of the aorta were 33.3, 0, 100, 94.1, 93.3% for Group I, II-A, II-B, III and IV respectively. The urinary output obtained in the postoperative 72 hours was significantly lower in Group I than in Group II, III and IV (Group I less than II less than IV less than III).(ABSTRACT TRUNCATED AT 250 WORDS)
Cardiopulmonary Bypass↗
Mutant rho factors with increased transcription termination activities. I. Functional correlations of the primary and secondary polynucleotide binding sites with the efficiency and site-selectivity of rho-dependent termination.
We have characterized rho proteins from mutants of Escherichia coli, rho s-81 and rho s-82, which are hyperactive in termination. The two mutant rho proteins are differentially altered both in termination activities and in RNA interactions. rho s-81 generally elicits enhanced termination on various templates such as phage T7 DNA and a DNA restriction fragment containing the trpE intracistronic rho-dependent terminators, either measured as a whole or examined for individual sites. On the other hand, rho s-82 has strikingly different preferences toward individual termination sites, exhibiting overall termination activities higher or lower than normal, depending on templates. From measurements of the rho ATPase activity with T7 RNA and various homoribopolymers as cofactors, both mutant rho proteins are shown to have broadened RNA base specificities in contrast to the stringent requirement for cytosine observed with the wild-type rho. Functional tests on the two kinds of polynucleotide binding sites known for rho have indicated that rho s-81 is mainly altered in the primary site, whereas rho s-82 is simultaneously affected in the secondary binding site as well as the primary site. Thus, we conclude that the primary and secondary sites contribute distinctly in determining the overall efficiency and site-specificity of termination, respectively. Further analysis of detailed termination points at the trpE and lambda tR1 terminators has revealed that major RNA transcripts generated by the wild-type rho and rho s-81 are notably rich in adenine and poor in cytosine for the 3'-terminal five to ten nucleotides, whereas those preferentially terminated by rho s-82 are conversely richer in cytosine than adenine. This finding suggests that rho may recognize the RNA-DNA hybrid region at the 3' end of a nascent transcript in its secondary binding reaction.
Adenosine Triphosphatases↗
Mutant rho factors with increased transcription termination activities. II. Identification and functional dissection of amino acid changes.
We have determined the nucleotide sequences of three mutant rho genes encoding hyperfunctional rho proteins (rho S) together with their parent allele, rho-ts702. These mutant rho factors contain the following amino acid changes as deduced from their sequences: (1) the thermo-labile mutant, rho-ts702, has Thr304 substituting for Ala; (2) rho S-77 and rho S-81, which are selectively altered in the primary polynucleotide binding site, share an identical mutation, Leu3----Phe; (3) rho S-82, which is altered in both the primary and secondary polynucleotide binding sites, carries three amino acid substitutions together, Leu3----Phe, Asp156----Asn and Thr323----Ile. Dissection and functional characterization of each mutation in rho S-82 have revealed that Ile323 alone is responsible for alterations in both the secondary RNA interaction and the terminator selectivity observed with the original mutant, rho S-82. Taken together, these results not only confirm our proposal in the accompanying paper that the primary and secondary RNA binding sites differently contribute in determining the overall efficiency and site-specificity of termination, respectively, but also support the possibility that these binding sites exist as structurally distinct domains in rho protein. In contrast, Asn156 was shown to cause decreased termination efficiency, though it had no influence on RNA interactions. Thus, this amino acid residue appears to be associated with still another rate-determining step of termination, for instance, interactions between rho and RNA polymerase. On the basis of Chou-Fasman secondary structure predictions as well as amino acid sequence comparison with F1-ATPase, we discuss how the proposed domains are structurally and functionally related to the putative ATPase reactive center of rho protein.
Adenosine Triphosphatases↗
Cloning and expression of a smooth muscle caldesmon.
Caldesmon is a smooth muscle and nonmuscle regulatory protein that interacts with actin, myosin, tropomyosin, and calmodulin. Two overlapping clones, isolated from a chicken oviduct cDNA plasmid library and a chicken gizzard cDNA lambda NM1149 library, were used to generate a 4108-base pair sequence coding for one caldesmon. Expression of the coding sequence confirms this is one of the large smooth muscle caldesmons. The deduced protein molecular weight is 86.974, significantly less than the molecular weights estimated by sodium dodecyl sulfate gel electrophoresis. The protein has a high content of Gly, Lys, Arg, and Ala; there are two cysteine residues, one at either end of the molecule. Comparison with the Protein Identification Resource database demonstrates a similarity with a tropomyosin binding domain of troponin T, but none with any calmodulin or actin binding proteins. The center of the protein has an 8-fold repeat of a 13 amino acid sequence whose general motif is -Glu3-(Lys/Arg)2-Ala2-Glu2-(Lys/Arg)1-X-(Lys/Arg)1-Ala1-, where X is Glu, Gln, or Ala. Comparison with peptide sequences from a chymotryptic fragment that binds actin and calmodulin places this domain on the C terminus of caldesmon adjacent to the troponin T similarity. A tentative map of the major binding domains is proposed on the basis of available data.
Amino Acid Sequence↗
Mechanism of diuretic action of U-62,066E, a kappa opioid receptor agonist.
The mechanism of the diuretic action of U-62,066E, a highly selective kappa opioid agonist, was examined in unanesthetized rats and in isolated perfused inner medullary collecting ducts (IMCD). In Long-Evans rats, U-62,066E caused a dose-dependent increase in urine flow and a decrease in urine osmolality without affecting urinary excretion of Na+. The diuretic effect of U-62,066E was blocked by MR-2266, a kappa opioid receptor antagonist. U-62,066E showed no diuretic effect in homozygous hereditary diabetes insipidus rats (Brattleboro strain). In water-deprived rats, U-62,066E markedly inhibited plasma arginine vasopressin (AVP) levels through a kappa receptor-mediated mechanism. In rat IMCD perfused in vitro, 10(-5) M U-62,066E did not inhibit either the baseline or the AVP-stimulated osmotic water permeability. We conclude that the inhibition of the release of AVP is the major if not the entire mechanism of the diuretic action of U-62,066E in rats. Although we ruled out the effect of this drug on the water permeability of IMCD, possible direct effects on other nephron structures remain to be established.
Animals↗
Methylation strongly enhances DNA bending in the replication origin region of the Escherichia coli chromosome.
Two-dimensional gel electrophoresis, at high and low temperatures, and gel mobilities of circularly permuted DNA segments showed a large bending locus about 50 bp downstream from the right border of the 245 bp oriC box, a minimal essential region of autonomous replication on the Escherichia coli chromosome. Bending was strongly enhanced by Dam methylation. In DNA from a Dam- strain, the mobility anomaly arising from altered conformation was much reduced, but was raised to the original level by methylation in vivo or in vitro. Enhancement of the mobility anomaly was also observed by hybrid formation of the Dam- strand with the Dam+ strand. Near the bending center, GATC, the target of Dam methylase, occurs seven times arranged essentially on the same face of the helix with 10.5 bp per turn. We concluded that small bends at each Dam site added up to the large bending detectable by gel electrophoresis.
Bacterial Proteins↗
Effect of high NaCl intake on Na+ and K+ transport in the rabbit distal convoluted tubule.
Morphological studies have demonstrated that a chronic increase in distal Na+ delivery causes hypertrophy of the distal convoluted tubule (DCT). To examine whether high NaCl-intake also causes functional changes in the well defined DCT, we measured transmural voltage (VT), lumen-to-bath Na+ flux (JNa(LB], and net K+ secretion (JK(net] in DCTs obtained from control rabbits and those on high NaCl-intake diets. The lumen negative VT was significantly greater in the high NaCl group than in the control group. The net K+ secretion (pmol mm-1 min-1) was greater in the high NaCl-intake group (54.1 +/- 13.0 vs 14.7 +/- 5.6). The K+ permeabilities in both luminal and basolateral DCT membranes, as assessed by the K+-induced transepithelial voltage deflection inhibitable with Ba2+, were increased in the experimental group. The lumen-to-bath 22Na flux (pmol mm-1 min-1) was also greater in the experimental group (726 +/- 119 vs 396 +/- 65). The VT component inhibitable with amiloride was also elevated in the high NaCl-intake group. Furthermore, Na+-K+-ATPase activity of the DCT was higher in the experimental than in the control group. We conclude that high NaCl intake increases both Na+ reabsorption and K+ secretion by the DCT. This phenomenon is associated with an increased Na+-K+-ATPase activity along with increased Na+ and K+ permeabilities of the luminal membrane, and an increase in the K+ permeability of the basolateral membrane. Cellular mechanisms underlying these functional changes remain to be established.
Aldosterone↗
Electrophysiological characterization of rabbit distal convoluted tubule cell.
The distal convoluted tubule (DCT) from rabbit kidney were perfused in vitro to study the conductive properties of the cell membranes by using electrophysiological methods. When the lumen and the bath were perfused with a bicarbonate free solution buffered with HEPES, the transepithelial voltage (VT) averaged -2.8 +/- 0.6 mV (n = 20), lumen negative. The basolateral membrane voltage (VB) averaged -77.8 +/- 1.1 mV (n = 33) obtained by intracellular impalement of microelectrodes. Cable analysis performed by injecting a current from perfusion pipette revealed that the transepithelial resistance was 21.8 +/- 1.7 omega.cm2 and the fractional resistance of the luminal membrane was 0.78 +/- 0.03 (n = 8), indicating the existence of ionic conductances in the luminal membrane. Addition of amiloride (10(-5) mol/l) to the luminal perfusate or Na+ removal from the lumen abolished the lumen negative VT and hyperpolarized the apical membrane. An increase in luminal K+ concentration from 5 to 50 mmol/l reduced the apical membrane potential (VA) by 37.5 +/- 2.6 mV (n = 7), whereas a reduction of Cl- in the luminal perfusate did not change VA significantly (0.5 +/- 0.5 mV, n = 4). Addition of Ba2+ to the lumen reduced VA by 42.6 +/- 1.0 mV (n = 4). When the bathing fluid was perfused with 50 mmol/l K+ solution, the basolateral membrane voltage (VB) fell from -76.8 +/- 1.5 to -31.0 +/- 1.3 mV (n = 18), and addition of Ba2+ to the bath reduced VB by 18.3 +/- 4.8 mV (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)
Amiloride↗
Autoradiographic localization of [125I]-endothelin-1 binding sites in rat brain.
Autoradiograms of [125I]-endothelin (ET) binding in the rat brain demonstrated that the receptors for endothelin are localized mainly in the brainstem, basal ganglia, and cerebellum. Among the many other nuclei in these regions, there also appeared nuclei which are considered to play important roles in the central nervous regulation of the cardiovascular system: they include the nuclei of the anteroventral third ventricle area, the supraoptic nucleus, and the subfornical organ, for example. From these findings, we suggest that ET-1 or its analogous peptide(s) may act as a neuropeptide regulating central nervous functions, including cardiovascular functions.
Animals↗
Automated spinal cord monitoring for spinal surgery.
A microcomputer-based automated spinal cord monitoring system was developed and 56 spinal operations have been carried out with it since 1986. The system comprises an electrodiagnostic system (Dantec 2000M), an FM tape recorder, a channel selector, an electrical relay, a Modem and a microcomputer which controls all of the elements. The program allowed for automated recording and analysis of evoked potentials during spinal surgery and alarm signals were generated according to the criteria of amplitude decrease and latency delay. It was demonstrated that automated spinal cord monitoring in the operating room was performed easily, reliably and safely allowing the surgeon to react quickly to possible compromise of the spinal cord. The design and usefulness of the system is described in this report.
Diagnosis, Computer-Assisted↗
Uncoupling of the cytochrome P-450cam monooxygenase reaction by a single mutation, threonine-252 to alanine or valine: possible role of the hydroxy amino acid in oxygen activation.
Site-directed mutants of cytochrome P-450cam (the cytochrome P-450 that acts as the terminal monooxygenase in the d-camphor monooxygenase system), in which threonine-252 had been changed to alanine, valine, or serine, were employed to study the role of the hydroxy amino acid in the monooxygenase reaction. The mutant enzymes were expressed in Escherichia coli and were purified by a conventional method. All the mutant enzymes in the presence of d-camphor exhibited optical absorption spectra almost indistinguishable from those of the wild-type enzyme in their ferric, ferrous, oxygenated, and carbon monoxide ferrous forms. In a reconstituted system with putidaredoxin and its reductase, the alanine enzyme consumed O2 at a rate (1100 per min per heme) comparable to that of the wild-type enzyme (1330 per min per heme), whereas the amount of exo-5-hydroxycamphor formed was less than 10% of that formed by the wild-type enzyme. About 85% of the O2 consumed was recovered as H2O2. The valine enzyme also exhibited an oxidase activity to yield H2O2 accompanied by a relative decrease in the monooxygenase activity. On the other hand, the serine enzyme exhibited essentially the same monooxygenase activity as that of the wild-type enzyme. Thus, uncoupling of O2 consumption from the monooxygenase function was produced by the substitution of an amino acid without a hydroxyl group. When binding of O2 to the ferrous forms was examined, the alanine and valine enzymes formed instantaneously an oxygenated form, which slowly decomposed to the ferric form with rates of 5.5 and 3.2 x 10(-3) sec-1 for the former and latter enzymes, respectively. Since these rates were too slow to account for the overall rates of O2 consumption, the formation of H2O2 was considered to proceed not by way of this route but through the decomposition of a peroxide complex formed by reduction of the oxygenated form by reduced putidaredoxin. Based on these findings, a possible mechanism for oxygen activation in this monooxygenase reaction has been discussed.
Alanine↗
Binding sites for endothelin-1 in rat tissues: an autoradiographic study.
By tissue autoradiography in the rat, we demonstrated that receptors for endothelin-1 (ET-1) were distributed not only in the cardiovascular system but also in the noncardiovascular organs including the brain, lung, intestine, etc. In the brain, the receptors were mainly found in the basal ganglia and brainstem, in which nuclei are known to be cardiovascular regulatory sites. In addition to its direct vasoconstricting action, ET-1 may exert neural cardiovascular control as a neuropeptide.
Animals↗
Interleukin 1 regulation of interleukin 2 and interferon-gamma gene activation in a human leukemic HSB.2 subclone.
The role of interleukin 1 (IL1) in causing IL2 and interferon-gamma (IFN-gamma) production and their associated gene activation has been studied in a human leukemic HSB.2 subclone. One of the subclones, HSB.2-C5B2 clone #28, which produced only low levels of IL2 and IFN-gamma when stimulated with phytohemagglutinin (PHA) or with a combination of phorbol-myristate-acetate (PMA) and Ca2+ ionophore, ionomycin, showed marked IL2 and IFN-gamma production in the presence of IL1. The augmentation by IL1 was observed in both dot and Northern blot analysis, indicating that IL1 regulates lymphokine genes at the pretranslational level. The kinetics of IL2 and IFN-gamma production were essentially similar for both lymphokines except that there was a faster accumulation of IFN-gamma mRNA than IL2 mRNA. In contrast to the IL2 and IFN-gamma gene activation, IL2 receptor (Tac/p55 antigen) expression was induced directly by IL1 itself as with PMA in this subclone. In these studies, IL1 action was not replaced by the drugs raising intracellular cyclic AMP (cAMP). Taken collectively, these experiments support the notion that IL1 does not trigger IL2 gene activation per se, but amplifies the preactivated lymphokine genes initiated by PMA and ionomycin, whereas IL1 can activate the IL2 receptor gene without any other known signal requirements.
Blotting, Northern↗
In vivo antitumor mechanism of natural human tumor necrosis factor involving a T cell-mediated immunological route.
We have investigated the in vivo antitumor mechanism of natural human tumor necrosis factor (n-TNF) isolated from a culture of human leukemic B cell line (BALL-1), especially its action as an immunomodulator, and found that the in vivo antitumor effect of n-TNF on Meth A sarcoma implanted in BALB/c mice pretreated with monoclonal antibody against T cell-specific surface antigen (Thy-1) was significantly diminished. Furthermore, when BALB/c mice were treated with T cell subset-specific monoclonal antibodies, anti-L3T4 or anti-Lyt-2.2, the antitumor effect of n-TNF on Meth A sarcoma was significantly reduced. Therefore, it was suggested that the in vivo antitumor mechanism of n-TNF might involve a T cell-mediated immunological route.
Animals↗
Acute aortic dissection due to giant cell arteritis. Report of two autopsy cases.
Two autopsy cases of giant cell arteritis with aortic dissection are reported. One patient was an 87-year-old man, and the other was an 80-year-old woman. In both cases the patient died suddenly, and fatal pericardial bleeding due to the aortic dissection was revealed at autopsy. Histologically, marked inflammation with giant cells was observed in the wall of the aorta and in other arteries including the cranial arteries. The authors therefore consider that giant cell arteritis was one of the preceding lesions that culminated in aortic dissection.
Aged↗
Autoradiographic distribution in rat tissues of binding sites for endothelin: a neuropeptide?
Endothelin (ET) is a potent and long-acting vasoconstrictor peptide consisting of 21 amino acids and recently isolated from a medium of cultured porcine endothelial cells. To determine the possible sites of ET action, we have conducted autoradiography and receptor binding assays with 125I-labeled ET in rat tissues. The displaceable binding sites of the ligand were widely distributed, not only in the arteries and heart but also in various other organs, e.g., brain, kidney, lung, adrenal gland, and intestine. The systemically injected ET did not cross the blood-brain barrier, whereas the ligand, applied in vitro, was mainly located in the hypothalamic and thalamic areas, lateral ventricular region, subfornical organ, globus pallidus, and caudate putamen. Both membrane preparations from the brain stem including diencephalon and from the heart ventricle had similar, specific, and high-affinity binding sites for 125I-ET. We suggest that ET is involved in the regulation of a large variety of organ functions and may also act as a neuropeptide.
Animals↗