Metabolically based treatment of stunned myocardium

Reversible myocardial ischemia is associated with a rapid decrease in contractility and prolonged postischemic ventricular dysfunction, due in part to altered intracellular calcium handling and/or contractile protein dysfunction. The maintenance of intracellular calcium homeostasis and force development by the contractile apparatus are dependent upon the free energy derived from ATP hydrolysis. This energy of hydrolysis is determined by the myocardial phosphorylation potential, an estimate of which can be made from the ratio (CrP)/(Cr) x (P(i)). Results from in vitro and in vivo studies suggest that pyruvate enhances contractility in both normal and stunned myocardium by enhancing myocardial phosphorylation potential. In regionally stunned porcine myocardium, pyruvate infusion increased recovery of regional ventricular function from 33% +/- 4% of preischemic systolic wall thickening to 81% +/- 4% and increased the (CrP)/(Cr) x (P(i)) ratio fivefold from 0.21 +/- 0.04 to 1.05 +/- 0.08. Thus, metabolic substrates that enhance myocardial energetics and ventricular function may be effective agents for attenuating postischemic ventricular function.

Delayed rectifier potassium current (IK) in latent atrial pacemaker cells isolated from cat right atrium

Whole-cell recording techniques were used to study the delayed rectifier K+ current (IK) in latent pacemaker cells isolated from cat right atrium. From a holding potential of -40 mV, depolarizing clamp steps elicited L-type Ca2+ current followed by an increasing outward current (IK). The time course of tail current amplitudes paralleled that of the time-dependent activation of outward current. Activation of IK exhibited a sigmoidal time course that was best fit by a power function where the activation variable was raised to the second power. The voltage-dependence of IK activation exhibited a sigmoidal relationship between -40 and +30 mV. The half-maximal activation voltage and slope factor were -21.9 +/- 1.3 and 13.8 +/- 0.9 mV respectively (n = 6). The fully activated I/V relationship of IK was linear between -100 and -30 mV and inwardly rectified at more positive voltages. Following IK activation, hyperpolarizations more negative than about -50 mV elicited tail currents that consisted of both IK deactivation and I(f) activation. A subtraction protocol was used to isolate IK tail currents. In 5.4 mM extracellular [K+], IK tail currents exhibited a reversal potential of -78.2 +/- 0.3 mV (n = 6). The reversal potential of IK was linearly related to log extracellular [K] and the slope was 51.5 mV per ten-fold change in extracellular [K]. At -70 mV, IK tail currents decayed as a single exponential function with a time constant of 159 +/- 16 ms (n = 6). These results indicate that latent atrial pacemakers exhibit IK activated by depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)

4-1BB T-cell antigen binds to mature B cells and macrophages, and costimulates anti-mu-primed splenic B cells

4-1BB is expressed on activated murine T cells and may function as an accessory signaling molecule during T-cell activation. To identify putative 4-1BB ligands, a fusion protein consisting of the extracellular domain of 4-1BB fused to human placental alkaline phosphatase (4-1BB-AP) was constructed. Alkaline phosphatase activity could then be used as an indicator of the relative amount of bound 4-1BB. These studies indicated that 4-1BB-AP specifically bound to the surface of various mature B and macrophage cell lines. 4-1BB-AP bound at low levels to T cell lines (non-activated and anti-CD3-activated), pre-B-cell lines, and an immature macrophage cell line. 4-1BB-AP did not bind to a glial tumor cell line, HeLa cells, or COS cells. In addition, 4-1BB-AP bound at higher levels to F(ab')2 anti-mu-activated primary B cells compared to anti-CD3-activated primary T cells. Scatchard analysis indicated that the A20 B cell lymphoma expressed 3680 binding sites per cell with a Kd of 1.86 nM. Affinity cross-linking studies demonstrated that a major cell surface species of 120 kDa bound to 4-1BB-AP; 4-1BB-AP also bound to a minor species of approximately 60 kDa. The addition of paraformaldehyde-fixed SF21 cells expressing recombinant 4-1BB synergized with F(ab')2 anti-mu in inducing splenic B cell proliferation suggesting that 4-1BB may function as a regulator of B cell growth.

Convergence of quantum electrodynamics in a curved modification of Minkowski space

The interaction and total hamiltonians for quantum electrodynamics, in the interaction representation, are entirely regular self-adjoint operators in Hilbert space, in the universal covering manifold M of the conformal compactification of Minkowski space Mo. (M is conformally equivalent to the Einstein universe E, in which Mo may be canonically imbedded.) In a fixed Lorentz frame this may be expressed as convergence in a spherical space with suitable periodic boundary conditions in time. The traditional relativistic theory is the formal limit of the present variant as the space curvature vanishes.

In vitro femoral arterial responses to vasoconstrictor and vasodilator agents in endotoxin shock

The hypothesis for this study is that the decreased arterial response to catecholamines may be due to the effect of endotoxemia on vessel tone. One control ring was taken from one femoral artery of a Wistar rat and after endotoxin (ENDT) infusion (i.v. 6 mg/kg-1 hr.), one ring was removed from the contralateral artery. The post-ENDT rings were tested in four groups which were determined by the mean arterial pressure (MAP) levels at the time of dissection: 100 mmHg (120 min), 80 mmHg (270 min), 60 mmHg (300 min) or 40 mmHg (330 min). KCl, phenylephrine (PHE) and arginine-vasopressin (AVP) dose-response curves (DR) were obtained at a preload of 500 mg which allowed the maximum response in control rings. When compared at 500 mg preload the maximal active response to all agonists post-ENDT was decreased by about 50%. By increasing the preload on the ENDT rings to 800 mg, the active tension became 2.49 times the active tension of the control rings. Length-tension experiments also showed a greater response for post-ENDT rings and a greater preload at maximum response but the ring circumference was the same. In contrast the in vivo femoral artery diameters at 90 min post-ENDT (100 mmHg) were 82.6% of control. Endothelium-dependent relaxation by acetylcholine (ACh) was abolished by ENDT but endothelium-independent relaxation to nitroprusside (NP) was not affected. It is concluded that the resting tone and active tension of femoral artery smooth muscle is increased by ENDT and the decreased in vivo responsiveness to vasoconstrictor agonists may be the result of vessel constriction due to loss of endothelium. The results also suggest that in vitro comparison of vessels in studies of endotoxin shock be done at the same muscle length rather than at the same preload.

Fast gradient-based methods for Bayesian reconstruction of transmission and emission PET images

The authors describe conjugate gradient algorithms for reconstruction of transmission and emission PET images. The reconstructions are based on a Bayesian formulation, where the data are modeled as a collection of independent Poisson random variables and the image is modeled using a Markov random field. A conjugate gradient algorithm is used to compute a maximum a posteriori (MAP) estimate of the image by maximizing over the posterior density. To ensure nonnegativity of the solution, a penalty function is used to convert the problem to one of unconstrained optimization. Preconditioners are used to enhance convergence rates. These methods generally achieve effective convergence in 15-25 iterations. Reconstructions are presented of an (18)FDG whole body scan from data collected using a Siemens/CTI ECAT931 whole body system. These results indicate significant improvements in emission image quality using the Bayesian approach, in comparison to filtered backprojection, particularly when reprojections of the MAP transmission image are used in place of the standard attenuation correction factors.

[Quantitative determination of rhapontin in root of Rheum hotaoense by TLC-scanning]

The contents of rhapontin in the root of Rheum hotaoense were determined by CS-920 TLC-scanning of silica gel plate A mixture of benzene-EtOAc-EtOH (5 : 3, 5 : 1.5) was used as the developing solvent. Recovery was 100.44%, RSD 3.0%.

DUN1 encodes a protein kinase that controls the DNA damage response in yeast

DNA damage induces the expression of many genes proposed to enhance DNA repair capacities. We investigated the mechanism by which DNA damage induces transcription of RNR3, a subunit of ribonucleotide reductase. Five complementation groups of DNA-damage uninducible (dun) mutants were identified. Each is sensitive to DNA damage. dun1 mutants are also defective for RNR1 and RNR2 induction but are proficient for induction of other genes, defining the existence of at least two distinct DNA damage induction pathways. DUN1 encodes a nuclear protein kinase that is also a phosphoprotein. Phosphorylation of Dun1 increases in response to DNA damage in a Dun1-dependent manner, suggesting an increase in autophosphorylation activity. These results establish the existence of a eukaryotic SOS response regulated by protein phosphorylation.

[A study of CGRP receptor and its effect on the growth of human pancreatic carcinoma cells]

In the present studies the calcitonin gene-related peptide (CGRP) receptors were characterized by radioligand analysis and the effect of CGRP and CGRP receptor antagonist on the growth of human pancreatic carcinoma cells (PU-PAN-1) was determined by 3H-TdR incorporation assay. The results indicated that human pancreatic carcinoma cells possess distinct CGRP receptors. CGRP stimulated the growth of PU-PAN-1 tumor cells, and CGRP receptor antagonist CGRP8-37 inhibited these effects. These results suggests that CGRP receptors may play an important role in the growth of human pancreatic carcinoma cells (PU-PAN-1).

Calcium permeability of nicotinic acetylcholine receptor channels in bovine adrenal chromaffin cells

The fractional contribution of Ca to current flow through neuronal-type nicotinic acetylcholine receptor channels was determined by quantitative fluorescence microfluorimetry using fura-2. The method, which has been applied already to several types of cells and channels is described in detail here. At -70 mV and 2 mM external Ca concentration it was found that Ca contributes 2.5% to the net current. The fractional contribution was found to be voltage dependent, increasing at negative potentials e-fold for a 110 mV potential difference. Total non-specific cation current was found to have a bell-shaped dependence on external Ca concentration peaking at 2 mM.

[Detection of the direct genotyping of HSV by PCR and its primal usage in ophthalmology]

The direct genotyping of Herpes Simplex Virus (HSV) by polymerase chain reaction (PCR) was used to analysis the smears from corneas or tears of 37 cases suspected HSK. The results show that PCR is a sensitive rapid and simple method. The key procedure is taking specimens.

Expression of gap junction connexin 43 and connexin 43 mRNA in different regional tissues of intestine in dog

To determine the distribution of gap junction protein connexin 43 (Cx43) and the expression of Cx43 mRNA in different regions of canine small intestine and colon, modified Western blot and Northern blot techniques were used with a site-directed antibody raised against a synthetic peptide of Cx43 Anti-Cx43 (252-271) and a probe of 1.3-kb Cx43 cDNA. Equal amounts of plasma membrane enriched fraction (10 micrograms protein) from small intestinal and colonic circular muscle, longitudinal muscle, and colonic submucous plexus border of circular muscle (interstitial cells of Cajal rich layer, ICC) of the dog were resolved by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred onto nitrocellulose, and blotted by chemiluminescent assay. Different yet characteristic ratios of the immunoreactive gap junction proteins located at 43 and 40 kDa were found in membranes from small intestinal and colonic circular smooth muscle, and ICC. These results suggest that gap junction Cx43 in dog heart, dog small intestinal and colonic circular muscle, and ICC is homologous to rat heart. Furthermore, with the use of Northern blot hybridization with a 1.3-kb Cx43 cDNA, a 3.0-kb message was observed in small intestinal and colonic circular muscles, longitudinal muscles, and ICC. However, the mRNA signal of small intestinal circular muscle was the strongest and that of longitudinal muscle was weakest, especially from colon longitudinal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrophage inflammatory protein-1 alpha rapidly modulates its receptors and inhibits the anti-CD3 mAb-mediated proliferation of T lymphocytes

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) is a member of the intercrine/chemokine family which consists of basic, heparin-binding, small molecular weight proteins. We have previously shown that a T cell line, CTLL-R8, carried high-affinity receptors for MIP-1 alpha and the proliferation of CTLL-R8 cells was inhibited by murine recombinant (mr) MIP-1 alpha. We extended our previous studies to murine resting splenic T lymphocytes to determine whether the inhibition of T cell proliferation is a general property of MIP-1 alpha. The resting splenic T cells carried approximately 680 high-affinity binding sites for mrMIP-1 alpha; more than 90% of the primary T cells carried MIP-1 alpha receptors. When the T cells were stimulated with immobilized anti-CD3 mAb in the presence of accessory cells, the MIP-1 alpha binding was reduced. The lowest binding was obtained 2 h after anti-CD3 mAb stimulation due to the internalization of MIP-1 alpha receptors. mrMIP-1 alpha inhibited the anti-CD3 mAb-mediated proliferation of murine splenic T lymphocytes. The maximum inhibition was obtained when mrMIP-1 alpha was added 30 min before anti-CD3 mAb stimulation. Slight inhibition of T cell proliferation was observed when mrMIP-1 alpha was added at the same time as anti-CD3 mAb stimulation. These results indicate that T lymphocytes are regulated negatively by MIP-1 alpha, which occurs when the T cells are exposed to MIP-1 alpha before activation. The negative effect of MIP-1 alpha seems to be mediated in part by the inhibition of IL-2 production, for there was a reduction in both the IL-2 mRNA levels and the IL-2 activity in supernatants from T cells preincubated with MIP-1 alpha before anti-CD3 mAb stimulation.

Macrophage inflammatory protein-1 alpha rapidly modulates its receptors and inhibits the anti-CD3 mAb-mediated proliferation of T lymphocytes

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) is a member of the intercrine/chemokine family which consists of basic, heparin-binding, small molecular weight proteins. We have previously shown that a T cell line, CTLL-R8, carried high-affinity receptors for MIP-1 alpha and the proliferation of CTLL-R8 cells was inhibited by murine recombinant (mr) MIP-1 alpha. We extended our previous studies to murine resting splenic T lymphocytes to determine whether the inhibition of T cell proliferation is a general property of MIP-1 alpha. The resting splenic T cells carried approximately 680 high-affinity binding sites for mrMIP-1 alpha; more than 90% of the primary T cells carried MIP-1 alpha receptors. When the T cells were stimulated with immobilized anti-CD3 mAb in the presence of accessory cells, the MIP-1 alpha binding was reduced. The lowest binding was obtained 2 h after anti-CD3 mAb stimulation due to the internalization of MIP-1 alpha receptors. mrMIP-1 alpha inhibited the anti-CD3 mAb-mediated proliferation of murine splenic T lymphocytes. The maximum inhibition was obtained when mrMIP-1 alpha was added 30 min before anti-CD3 mAb stimulation. Slight inhibition of T cell proliferation was observed when mrMIP-1 alpha was added at the same time as anti-CD3 mAb stimulation. These results indicate that T lymphocytes are regulated negatively by MIP-1 alpha, which occurs when the T cells are exposed to MIP-1 alpha before activation. The negative effect of MIP-1 alpha seems to be mediated in part by the inhibition of IL-2 production, for there was a reduction in both the IL-2 mRNA levels and the IL-2 activity in supernatants from T cells preincubated with MIP-1 alpha before anti-CD3 mAb stimulation.

Effect of muscle length on the in vitro comparison of femoral arteries before and after endotoxin shock

Control and endotoxin-treated femoral arteries were compared in vitro for the effect of muscle length. Rats were anesthetized with pentobarbital, and endotoxin (6 mg/kg) was infused for 1 h. A control ring before endotoxin treatment and a ring after endotoxin treatment (blood pressure = 40 mmHg) were excised from the contralateral artery for length-tension and dose-response experiments with phenylephrine. The initial length for resting tension (Li) was shorter for endotoxic rings (1.23 +/- 0.01 vs. 1.41 +/- 0.02 mm in control), but the length of maximum active tension (Lmax) was the same. In length-tension experiments the values for active tension (6.36 +/- 0.61 vs. 4.06 +/- 0.60 x 10(3) dyn/cm), preload at Lmax (1,333 +/- 204 vs. 733 +/- 146 mg), and passive stiffness were increased after endotoxin. In dose-response experiments at the same preload, the endotoxic rings had a lower active tension (3.28 +/- 0.28 vs. 6.55 +/- 0.27 x 10(3) dyn/cm) but the same sensitivity. At Lmax, active tension (12.45 +/- 0.48 vs. 5.01 +/- 0.89 x 10(3) dyn/cm in control vessels) and sensitivity (half-maximum effective dose = 0.68 +/- 0.8 x 10(-6) vs. 1.39 +/- 0.29 x 10(-6) M in control vessels) were greater for endotoxic rings. These experiments show that phenylephrine sensitivity and active tension in the rat femoral artery are increased by endotoxin shock, and the importance of muscle length is implied.

Characterization of minisatellite sequences from Oryza sativa

Two DNA sequences were cloned from the genome of cultivated rice (Oryza sativa L.) by cross-hybridization with the human minisatellite sequence 33.6. The rice sequences consisted of tandem direct repeats, which showed significant similarity to the 33.6 consensus sequence. Profiles capable of distinguishing different rice cultivars were detected by cross-hybridization with a DNA probe amplified by the polymerase chain reaction from one of the rice minisatellite sequences.

Differences in arterial and arteriolar endothelial structure during endotoxin shock

Previous studies of physiological and ultrastructural assessment changes in the walls of the femoral artery and A1, A2, and A3 arterioles in the rat cremaster muscle after infusion of Escherichia coli endotoxin (ENDT) (6 mg/kg-1 hr. period) indicate there may be a difference in the alteration of the endothelial structure of arteries and arterioles. Functionally, ENDT has been shown to abolish acetylcholine (ACh)-induced relaxation in the femoral artery [Zhou, PhD dissertation, University of South Florida, Tampa, 1992]. Dilations of A1 arterioles were shown to be reduced, but dilations of A2 and A3 arterioles were not significantly changed from control [Baker and Sutton, Am J Physiol, 264:H 1118-H 1123, 1993]. In the current study, ultrastructural evaluation of femoral arterial tissue post-ENDT at the mean arterial pressure (MAP) of 100 mm Hg revealed partially destroyed endothelial cells. The MAP decreased as the animal progressed into shock. At 80 mm Hg, 60 mm Hg and 40 mm Hg, essentially all endothelial cells were destroyed, with the internal elastic lamina denuded. In contrast, endotoxin damage in the A1, A2, and A3 arterioles was minimal even at a MAP of 40 mm Hg. Endothelial cells of A1 arterioles post-ENDT had more vacuoles than at control. Therefore, arteriolar endothelium was functionally and anatomically relatively undamaged, consequent to endotoxin administration, in contrast to femoral arteries where the endothelium was destroyed in a short time.

[Extraction and homogeny of larvicidal toxin in Bacillus sphaericus strain C3-41]

Spore-crystal toxin and spore-wall protein of Bacillus sphaericus C3-41 were extracted respectively from spore-crystal complex. When subjected to SDS-PAGE, spore-crystal toxin might give two toxic protein bands (43 and 40 kilodaltons), but spore-wall protein had only a protein band (MW 104 kD), which was degraded into toxic 43 and 40 kD proteins by using NaOH. The LC50 values of spore-wall protein and spore-crystal toxin purified by Sephadex G-75 were 267 and 10 ng/ml respectively against the third instar larvae of Culex quinquefasciatus at 48 hours. The results of immunodiffusion showed that sodium hydroxide-solubilized spore-crystal toxins from spore-crystal complex of strain 2362, 1593, Bs-10 (H5a5b) and 2297 (H25) revealed cross reactions with 43 and 40 kD antiserum of strain C3-41, but those of strain K (H1), SS II-1, 1404 (H2) and 2315. (H26) without cross reaction with the same antiserum.

Mobile and immobile calcium buffers in bovine adrenal chromaffin cells

1. The calcium binding capacity (kappa S) of bovine chromaffin cells preloaded with fura-2 was measured during nystatin-perforated-patch recordings. 2. Subsequently, the perforated patch was ruptured to obtain a whole-cell recording situation, and the time course of kappa S was monitored during periods of up to one hour. 3. No rapid change (within 10-20 s) of kappa S was observed upon transition to whole-cell recording, as would be expected, if highly mobile organic anions contributed significantly to calcium buffering. However, approximately half of the cells investigated displayed a drop in kappa S within 2-5 min, indicative of the loss of soluble Ca2+ binding proteins in the range of 7-20 kDa. 4. The average Ca2+ binding capacity (differential ratio of bound calcium over free calcium) was 9 +/- 7 (mean +/- S.E.M.) for the poorly mobile component and 31 +/- 10 for the fixed component. It was concluded that a contribution of 7 from highly mobile buffer would have been detected, if present. Thus, this value can be considered as an upper bound to highly mobile Ca2+ buffer. 5. Both mobile and fixed calcium binding capacity appeared to have relatively low Ca2+ affinity, since kappa S did not change in the range of Ca2+ concentrations between 0.1 and 3 microM. 6. It was found that cellular autofluorescence and contributions to fluorescence of non-hydrolysed or compartmentalized dye contribute a serious error in estimation of kappa S. 'Balanced loading', a degree of fura-2 loading such that the calcium binding capacity of fura-2 equals cellular calcium binding capacity, minimizes these errors. Also, changes in kappa S at the transition from perforated-patch to whole-cell recording can be most faithfully recorded for similar degrees of loading in both situations. 7. Nystatin was found unable to make pores from inside of the plasma membrane of chromaffin cells. With careful preparation and storage the diluted nystatin solution maintained its high activity of membrane perforation for more than one week. 8. An equation for the effective diffusion constant for total cytoplasmic calcium, D'Ca, was derived, which takes into account fixed buffer and poorly mobile buffer as determined, as well as calcium bound to fura-2 and some highly mobile buffers.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro and in vivo disposition and metabolism of 3'-deoxy-2',3'-didehydrothymidine

The disposition and metabolic fate of 3'-deoxy-2',3'-didehydrothymidine (D4T) were evaluated both in isolated hepatocytes and in nonhuman primates. Rapid formation of thymine and beta-aminoisobutyric acid (BAIBA) occurred following incubation of hepatocytes with 10 microM [5(-3)H]D4T. Substantial levels of tritiated water were also detected. Exposure of cells to D4T in the presence of either 1 mM thymine or 10 microM benzyloxybenzyluracil, an inhibitor of dihydropyrimidine dehydrogenase, decreased intracellular BAIBA levels by approximately 89 and 63%, respectively. Concurrently, [3H]thymine levels increased two- to fivefold. These results are consistent with D4T being cleaved to thymine, which is then degraded to BAIBA. A similar metabolic disposition was observed in monkeys following administration of 25 mg of [5(-3)H]D4T per kg of body weight. BAIBA, thymine, and tritiated water were identified in plasma and urine. Approximately 50% of the administered dose was recovered in urine within 24 h, with the majority of the radioactivity representing unchanged drug. After administration intravenously or orally of 25 mg of [4(-14)C]D4T per kg of body weight to monkeys, a novel metabolite, designated X, in addition to unchanged D4T, thymine, and BAIBA, was also detected. The sum of the three metabolites and unchanged drug accounted for virtually all of the radioactivity in plasma and urine. Thymine and X exhibited kinetic profiles similar to that of D4T, with plasma elimination half-life of 2 to 3 h, whereas BAIBA levels remained constant for extended periods and declined slowly; this metabolite could be detected 24 h after intravenous drug administration. Mean oral bioavailability of D4T was high at approximately 70%. As observed in the [5(-3)H]D4T study performed in monkeys, approximately half of the administered [4(-14)C]D4T was recovered unchanged. The remainder was not recovered in urine or feces collected up to 30 days after drug administration. These data suggest that D4T metabolites are further metabolized by salvage pathways and/or converted to biological macromolecules.

Novel T cell antigen 4-1BB associates with the protein tyrosine kinase p56lck1

4-1BB is a 30-kDa inducible T cell Ag, and is expressed predominantly as a 55-kDa dimer on both CD4+ and CD8+ T lymphocytes. The cytoplasmic tail of 4-1BB contains the sequence Cys-Arg-Cys-Pro, which is similar to the sequence Cys-X-Cys-Pro, which mediates the binding of the CD4 and CD8 molecules to the protein tyrosine kinase p56lck. An anti-4-1BB mAb, 53A2, was used to determine whether 4-1BB may associate with p56lck. The 53A2 mAb specifically recognized 4-1BB on a CD8+ T cell line, CTLL-2, and coimmunoprecipitated a 56-kDa protein along with 4-1BB. Peptide mapping indicated that the 56-kDa phosphoprotein was identical to p56lck. The coimmunoprecipitation of p56lck with 4-1BB also occurred in nonlymphoid cells such as insect (Sf-21) and HeLa cells when the two recombinant proteins were coexpressed. Analysis of mutant p56lck recombinant proteins showed that two cysteine residues critical for p56lck-CD4 (or -CD8) complex formation are also required for the p56lck-4-1BB interaction. These studies establish that 4-1BB physically associates with p56lck.

[The clinicopathological research of post-operative recurrence of gall-bladder carcinoma]

This paper analyzed the clinicopathological factors relating to post-operative recurrence of gall-bladder carcinoma (GBC) in 71 cases, divided into group A (48 cases) dying within one year, and group B (23 cases) having been alive for longer than three years. Based on the "Japanese management rule of GBC surgery and GBC pathology" the indicators of clinicopathological S, n, binf, hinf, ly, V, morphological-classification, and histologic-classification showed significant difference between the 2 groups (P < 0.01). But pn, showed no significant difference between the 2 groups. In group A in gamma show 47.8%, Gn (+) 70.8%, curable operation 12.5%, this is worse results than group B (P < 0.01). Risk factors relating to early postoperative recurrence included: a. infiltrative way of gamma; b. deeply involved liver parenchyma (> 5 mm in-depth); c. cervical cancer. d. palliative resection.

Novel T cell antigen 4-1BB associates with the protein tyrosine kinase p56lck1

4-1BB is a 30-kDa inducible T cell Ag, and is expressed predominantly as a 55-kDa dimer on both CD4+ and CD8+ T lymphocytes. The cytoplasmic tail of 4-1BB contains the sequence Cys-Arg-Cys-Pro, which is similar to the sequence Cys-X-Cys-Pro, which mediates the binding of the CD4 and CD8 molecules to the protein tyrosine kinase p56lck. An anti-4-1BB mAb, 53A2, was used to determine whether 4-1BB may associate with p56lck. The 53A2 mAb specifically recognized 4-1BB on a CD8+ T cell line, CTLL-2, and coimmunoprecipitated a 56-kDa protein along with 4-1BB. Peptide mapping indicated that the 56-kDa phosphoprotein was identical to p56lck. The coimmunoprecipitation of p56lck with 4-1BB also occurred in nonlymphoid cells such as insect (Sf-21) and HeLa cells when the two recombinant proteins were coexpressed. Analysis of mutant p56lck recombinant proteins showed that two cysteine residues critical for p56lck-CD4 (or -CD8) complex formation are also required for the p56lck-4-1BB interaction. These studies establish that 4-1BB physically associates with p56lck.

Genotoxic effects of subacute treatments with wood dust extracts on the nasal epithelium of rats: assessment by the micronucleus and 32P-postlabelling

Human exposure to wood dust has been epidemiologically linked to a number of enhanced incidences of various neoplasias, including those of the nose. Among different suspected woods, long-term exposure to the dust of beech (Fagus silvatica) is strongly associated with development of these tumors. Experimentally, it has been shown that a simple alcoholic extract of beech wood dust is mutagenic toward some bacteria and tumorigenic on mouse skin. For the present study, different groups of male Wistar rats were treated with aqueous, ethanol, or methanol extract of untreated beech wood dust via nasal drip at three concentrations for 48 h. Animals were killed 24 h after the last treatment and the nasal tissues were isolated to be examined for possible induction of micronuclei and DNA adducts. A clear dose-dependent increase in the number of micronuclei (P < 0.01) was observed after treatment of rats with each alcoholic extract of wood dust. In contrast, no DNA adducts could be detected with these extracts using the 32P-postlabelling technique. No increased number of micronucleated cells was found with solvents alone or with aqueous extract of dust. These data might support the early hypothesis that wood dust per se contains some in vivo genotoxic and thus possibly carcinogenic components extractable by an alcohol.

Long-term use of IgA-depleted intravenous immunoglobulin in immunodeficient subjects with anti-IgA antibodies

The use of intravenous immunoglobulin is standard practice for antibody replacement in the humoral immunodeficiency diseases. Most infusions proceed uneventfully, but a proportion of infusions (5-8%) produces some degree of an infusion reaction. While the cause of most of these infusion reactions is unknown, an established, but rare cause of reactions is IgA antibodies in the serum of the patient, which apparently forms an immune complex with the traces of IgA in the infused immunoglobulin. This article describes our studies of five immunodeficient patients who had high-titered anti-IgA antibodies and a history of severe infusion reactions to intravenous immunoglobulin products not depleted of IgA (IgA content, 270-720 micrograms/ml). Over a 6-year period we gave these patients IgA-depleted intravenous immunoglobulin for a total of 170 infusions. These infusions were generally well tolerated; however, mild to moderate infusion reactions did occur in 9 of the 170 infusions (5.3%). These reactions were not related to the IgA content of the immunoglobulin solutions used--ascertained to vary between 0.4 and 2.9 micrograms/ml of IgA. Levels of plasma C3a and C4a increased after immunoglobulin infusions but the appearance of these components was not accompanied by any infusion reaction. We conclude that the long-term infusions of IgA-depleted intravenous immunoglobulin, within the range of IgA concentrations investigated, into patients with even very high-titered antibodies to IgA, is a safe practice.

Fractional contribution of calcium to the cation current through glutamate receptor channels

The Ca2+ fraction of the ion current flowing through glutamatergic NMDA and AMPA/kainate receptor channels was determined in forebrain neurons of the medial septum. The neurons were overloaded with the Ca2+ indicator dye fura-2 (1 mM) via the recording patch pipettes. This approach allowed the direct determination of the Ca2+ influx from changes in the Ca(2+)-sensitive fura-2 fluorescence. We found that, at negative membrane potentials and at an extracellular free Ca2+ concentration of 1.6 mM, the Ca2+ fraction of the current through the NMDA receptor channels is only 6.8%, about 2-fold lower than previously estimated from reversal potential measurements. Interestingly, a quite high fractional Ca2+ current of 1.4% was determined for the linearly conducting AMPA/kainate receptor channels found in these neurons.

Na(+)-Ca2+ exchange current in latent pacemaker cells isolated from cat right atrium

1. Single latent pacemaker cells were isolated from cat right atrium, and studied in a whole-cell configuration using a nystatin-perforated patch recording method. The nystatin method avoids alterations in intracellular Ca2+, cellular constituents and run-down of ionic currents. 2. Depolarizing voltage clamp pulses from -40 mV elicited L-type Ca2+ current (ICa) that exhibited an initial rapid phase of inactivation followed by a secondary slower inward current component that decayed over about 100 ms. The secondary inward component appeared as a slowly decaying inward tail current following short (10-40 ms) depolarizing clamp steps. 3. Slowly decaying inward currents were abolished by internally dialysing pacemaker cells with 2 mM EGTA using a ruptured patch recording method. Inward tail currents were also abolished by exposure to 1 microM ryanodine and significantly decreased by replacing 85% of external Na+ with lithium, without effect on peak ICa. These findings identify a Na(+)-Ca2+ exchange current (INa-Ca) that is mediated by sarcoplasmic reticulum (SR) Ca2+ release. 4. Properties of INa-Ca and ICa differed significantly: (i) ICa exhibited a bell-shaped voltage dependence that peaked at 0 mV and decreased at more positive voltages. INa-Ca was maximal at -10 mV and remained relatively constant at more positive voltages; (ii) a paired pulse protocol showed that the time course of INa-Ca recovery (5 s) was significantly longer than that of ICa (2 s); (iii) cadmium (50 microM) induced an inhibition of ICa that did not correlate in time with changes in INa-Ca. 5. The duration of depolarizing steps between 10 and 120 ms had no effect on the time course of INa-Ca tail currents. 6. Isoprenaline > or = 5 x 10(-8) M significantly increased peak ICa amplitude, peak INa-Ca amplitude, accelerated INa-Ca rate of decay and decreased the absolute time of INa-Ca decay. 7. Free-running pacemaker action potentials were clamped during diastole at either -40 or -70 mV (maximum diastolic potential) for variable periods of time. At times between 0.2 and 1 s, INa-Ca exhibited a voltage-dependent increase in amplitude over time, i.e. INa-Ca recovered more rapidly from -70 mV than from -40 mV. At times > 2 s, INa-Ca exhibited a voltage-dependent decline in amplitude over time, i.e. from -40 mV INa-Ca decreased by 10% of maximum whereas from -70 mV INa-Ca decreased by 60% of maximum.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of isoprenaline on I(f) current in latent pacemaker cells isolated from cat right atrium: ruptured vs. perforated patch whole-cell recording methods

Whole-cell recording techniques were used to study the time-dependent inward current activated on hyperpolarization (I(f)) and its response to isoprenaline in latent atrial pacemaker cells isolated from cat right atrium. To determine whether the response to isoprenaline depended on the type of recording method, we analysed I(f) using either a standard ruptured-patch, or a nystatin-perforated-patch, whole-cell recording method. All cells beat rhythmically at 35 degrees C and exhibited normal pacemaker action potentials and I(f) current, regardless of the recording method. With the ruptured-patch method, pacemaker action potentials ceased activity within a few minutes and I(f) amplitude decreased "ran down" to 74% of control within 10 min of rupturing the patch. Isoprenaline (1 microM) elicited variable changes in I(f) amplitude among different latent pacemaker cells resulting in no net change in mean current amplitude (n = 6). In addition, isoprenaline failed to change the voltage dependence of the I(f) activation curve. On the other hand, using a nystatin-perforated-patch method, pacemaker action potentials and I(f) exhibited no significant changes over the same 10 min period. Under these conditions, isoprenaline consistently increased I(f) in all cells studied (+90%) at -80 mV; n = 8), and increased the spontaneous rate of pacemaker action potentials by 58 +/- 7% (n = 5). Moreover, isoprenaline elicited a significant positive shift (+11 mV) in the half-maximal activation voltage of the I(f) activation curve (n = 3). We conclude that latent atrial pacemakers consistently exhibit I(f) current, and that isoprenaline consistently elicits an increase in I(f) amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and experimental studies on shallow needling technique for treating childhood diarrhea

Treatment of diarrhea in children by shallow needling and by drugs was studied in 3 separate groups for comparison. For Group I, the lateral line II of the forehead was taken, i.e. the upper, middle and lower points of the line staring from Toulinqi (UB 15) vertically downwards to the place 1 cm below the hairline were selected. For Group II, shallow needling was done on body acupoints, the main points selected being Qihai (Ren 6), Shuifen (Ren 9), bilateral Tianshu (St 25), and bilateral Zusanli (St 36); the adjuvant acupoints were Taibai (Sp 3) and Gongsun (Sp 4). The depth of shallow needling was merely puncturing the skin. For Group III the drugs used were Liteling, Berberine, Gentamycin, Ampicillin, and SMZ Co. The results of treatment in Group I and II differed insignificantly, while both were significantly superior to drugs in Group III. Experimental studies also showed that shallow needling enhanced the humoral and cellular immunity and promoted the intestinal peristaltic function.

DNA damage and cell cycle regulation of ribonucleotide reductase

Ribonucleotide reductase (RNR) catalyzes the rate limiting step in the production of deoxyribonucleotides needed for DNA synthesis. In addition to the well documented allosteric regulation, the synthesis of the enzyme is also tightly regulated at the level of transcription. mRNAs for both subunits are cell cycle regulated and inducible by DNA damage in all organisms examined, including E. coli, S. cerevisiae and H. sapiens. This DNA damage regulation is thought to provide a metabolic state that facilitates DNA replicational repair processes. S. cerevisiae also encodes a second large subunit gene, RNR3, that is expressed only in the presence of DNA damage. Genetic analysis of the DNA damage response in S. cerevisiae has shown that RNR expression is under both positive and negative control. Among mutants constitutive for RNR expression are the general transcriptional repression genes, SSN6 and TUP1. Mutations in POL1 and POL3 also activate RNR expression, indicating that the DNA damage sensory network may respond directly to blocks in DNA synthesis. A protein kinase, Dun1, has been identified that controls inducibility of RNR1, RNR2 and RNR3 in response to DNA damage and replication blocks. This result suggests that the RNR genes in S. cerevisiae form a regulon that is coordinately regulated by protein phosphorylation in response to DNA damage.

Changes in the level of perforin and its transcript during effector and target cell interactions

Perforin is a cytoplasmic granule protein expressed in cytotoxic lymphocytes, and is capable of lysing target cells. This protein is induced as cytotoxic T cells are activated, and the mRNA expression is modulated by various stimulators. These observations suggest possible changes in the level of perforin transcripts and protein when killer lymphocytes meet specific target cells leading to target cell death. To address this question, we examined three murine T-cell clones and primary human NK cells in perforin expression. When the cytotoxic lymphocytes were exposed to sensitive targets, perforin mRNA disappeared within 5 to 30 min and appeared within an hour thereafter. Among the murine T cell clones, L3 and OE4 showed two phases of mRNA decrease while human NK cells and the third murine T cell clone, AB.1, showed only one phase of mRNA loss during a 240 min period. The data indicate that when cytotoxic lymphocytes receive signals from a sensitive target, the cells rapidly degrade previously accumulated perforin mRNA and synthesize new transcripts. Interestingly, heat shock protein 70 mRNA was induced as the perforin mRNA levels recovered, while P55 Il-2 receptor mRNA was downregulated within 5 min after exposure to targets. The perforin protein level also rapidly decreased immediately after the interaction with the target, followed by a recovery, and then another decrease as seen in primary human NK cells, OE4 and L3 cells. However, in the AB.1 clone, no change in perforin content was detectable, despite the loss of perforin mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

IDDM patients' sera recognize a novel 30-kD pancreatic autoantigen related to chymotrypsinogen

We have examined, by western immunoblot analysis, the sera of 16 insulin-dependent diabetes mellitus patients (IDDM) for the presence of autoantibodies against proteins extracted from islet-cell enriched preparations of normal human pancreata. A novel putative autoantigen recognized by late stage IDDM patients sera was identified, and its amino acid sequence was partially determined. Islets of Langerhans were partially purified by a modified collagenase digestion procedure, and subsequent protein extracts were fractionated by one-dimensional or two-dimensional polyacrylamide gel electrophoresis (1-D or 2-D SDS-PAGE). Immunoblot analysis revealed a 30-kD species which was recognized by 4 of 16 IDDM patients sera, but none of 16 normal sera. The 30-kD protein, appeared as a single band on 1-D SDS-PAGE, but was resolved on 2-D gel electrophoresis as several distinct protein species with different isoelectric points (pI's), ranging from 7 to 9. The amino terminal sequence of one such species was partially determined by microsequencing, and the second through the fourteenth amino acids were found to be identical to the corresponding sequence in human chymotrypsinogen. The fifteenth through the eighteenth amino acids were different from the known chymotrypsinogen sequence. This region corresponds with the site that is cleaved to activate chymotrypsinogen. Based on the size and sequence homology, this antigen appears to be related to chymotrypsinogen. We conclude that this 30-kD species may be an autoantigen in some late stage IDDM patients.

Pheromone-induced signal transduction in Saccharomyces cerevisiae requires the sequential function of three protein kinases

Protein phosphorylation plays an important role in pheromone-induced differentiation processes of haploid yeast cells. Among the components necessary for signal transduction are the STE7 and STE11 kinases and either one of the redundant FUS3 and KSS1 kinases. FUS3 and presumably KSS1 are phosphorylated and activated during pheromone induction by a STE7-dependent mechanism. Pheromone also induces the accumulation of STE7 in a hyperphosphorylated form. This modification of STE7 requires the STE11 kinase, which is proposed to act before STE7 during signal transmission. Surprisingly, STE7 hyperphosphorylation also requires a functional FUS3 (or KSS1) kinase. Using in vitro assays for FUS3 phosphorylation, we show that pheromone activates STE7 even in the absence of FUS3 and KSS1. Therefore, STE7 activation must precede modification of FUS3 (and KSS1). These findings suggest that STE7 hyperphosphorylation is a consequence of its activation but not the determining event.

MAP kinase-related FUS3 from S. cerevisiae is activated by STE7 in vitro

Pheromone-stimulated haploid yeast cells undergo a differentiation process that allows them to mate. Transmission of the intracellular signal involves threonine and tyrosine phosphorylation of the redundant FUS3 and KSS1 kinases, which are members of the MAP kinase family. FUS3/KSS1 phosphorylation depends on two additional kinases, STE11 and STE7 (refs 2, 5, 6). Genetic analyses predict an ordered pathway where STE11 acts before STE7 and FUS3/KSS1 (refs 2, 7). Here we report that STE7 is a dual-specificity kinase that modifies FUS3 at the appropriate sites and stimulates its catalytic activity in vitro. From these data and previous genetic results, we argue that STE7 is the physiological activator of FUS3. Recent indications that MAP kinase activators are related to STE7 suggest that signal transduction pathways in many, if not all, eukaryotic organisms use homologous kinase cascades.

Inducible T cell antigen 4-1BB. Analysis of expression and function

4-1BB is an inducible receptor-like protein expressed in both cytolytic and Th cells. Optimal induction of 4-1BB mRNA in T cells required both PMA and ionomycin stimulation, indicating that protein kinase C activation and increases in intracellular Ca2+ were required for its expression. 4-1BB was categorized as an early activation gene since the protein synthesis inhibitor, cycloheximide, blocked the induction of 4-1BB mRNA. A rat mAb, 53A2, was generated against recombinant soluble 4-1BB and was used to characterize this molecule. 4-1BB is a 30-kDa glycoprotein and appears to exist as both a monomer and a 55-kDa dimer on the cell surface of a T cell clone. The 4-1BB protein may be post-translationally modified since its predicted backbone is 25 kDa. FACS analysis indicated that 4-1BB was inducible and expressed on the cell surface of activated splenic T cells and thymocytes. Cross-linking of 4-1BB on anti-CD3-stimulated T cells with 53A2 resulted in a dramatic enhancement of T cell proliferation. This suggests that 4-1BB may function as an accessory signaling molecule during T cell activation.

Complex karyotypic abnormalities including t(8;22) in a patient with chronic lymphocytic leukemia

The case of a 49-year-old Chinese man with B-cell chronic lymphocytic leukemia (B-CLL) is presented. Complex karyotypic abnormalities comprising t(8;22)(q24;q11), trisomy 7, a deletion of 11q, and two small marker chromosomes were observed in PWM-stimulated cultures of his peripheral blood cells. To our knowledge, this is the first report of a t(8;22) in CLL.

Inducible T cell antigen 4-1BB. Analysis of expression and function

4-1BB is an inducible receptor-like protein expressed in both cytolytic and Th cells. Optimal induction of 4-1BB mRNA in T cells required both PMA and ionomycin stimulation, indicating that protein kinase C activation and increases in intracellular Ca2+ were required for its expression. 4-1BB was categorized as an early activation gene since the protein synthesis inhibitor, cycloheximide, blocked the induction of 4-1BB mRNA. A rat mAb, 53A2, was generated against recombinant soluble 4-1BB and was used to characterize this molecule. 4-1BB is a 30-kDa glycoprotein and appears to exist as both a monomer and a 55-kDa dimer on the cell surface of a T cell clone. The 4-1BB protein may be post-translationally modified since its predicted backbone is 25 kDa. FACS analysis indicated that 4-1BB was inducible and expressed on the cell surface of activated splenic T cells and thymocytes. Cross-linking of 4-1BB on anti-CD3-stimulated T cells with 53A2 resulted in a dramatic enhancement of T cell proliferation. This suggests that 4-1BB may function as an accessory signaling molecule during T cell activation.

Evaluation of 90:10 poly(D,L-lactide-co-glycolide) microspheres containing norethisterone: drug release and biodegradation

Poly(D,L-lactide-co-glycolide) (PLG, 90:10) microspheres containing 20% norethisterone (NET) were prepared by solvent evaporation method. Microspheres in the size ranges of 65 to 100 microns were sterilized by irradiation and used for further study. In vitro release showed fairly constant release of NET from the above microspheres over more than 90 days. However, in vivo drug release determined by residual NET analysis after i.m. injection in rats indicated a faster release rate. About 95% of NET was released in a period of 45 days. At the dose of 80 mg of microspheres, vaginal estrus cycles were inhibited for 45 days compared to 27 days for the same dose of NET crystals in rats. Biodegradation of the microspheres was tested by direct measurement of molecular weight losses and SEM observation of morphological changes of the microspheres, which showed continuous erosion in the internal matrix of microspheres with the decrease of molecular weight of PLG until total collapse of microspheres, and biodegradation was faster in rats than in human serum at 37 degrees C in vitro. Total degradation of 90:10 PLG microspheres was less than 7 months in rats and more than 9 months in vitro.

Mesangioproliferative glomerulonephritis in mink with encephalitozoonosis

Renal specimens from 6 mink with encephalitozoonosis were studied by light and electron microscopy and immunohistochemistry. The glomeruli of affected kidneys had a mesangioproliferative glomerulonephritis which was characterized by an increase in mesangial cells and matrix in most glomeruli. Some glomeruli were partially or completely sclerosed. There were protein or granular casts in the cortical and medullary tubules. Interstitial nephritis, vasculitis and tubular cysts were found. Electron microscopy demonstrated extensive matrix and increased cellularity in the mesangial areas. Glomeruli showed segmentally thickened or wrinkled capillary basement membranes. Electron dense deposits were found in the glomerular basement membranes and mesangium. Peroxidase-anti-peroxidase immunohistochemistry demonstrated that IgG and IgM positive material was present as granular deposits in the glomerular basement membrane and occasionally in the mesangium.

Molecular genetics of human androgen insensitivity

Androgen insensitivity syndromes represent one cause of human male pseudohermaphroditism related to defects in the androgen receptor. The formation of a biologically active androgen receptor complex with testosterone and 5 alpha-dihydrotestosterone is required for normal androgen action during fetal development and differentiation of the internal accessory sex glands and external genitalia. Cloning of the human androgen receptor complementary DNA and genetic screening of human subjects with the clinical and biochemical features of androgen insensitivity using the polymerase chain reaction, denaturing gradient gel electrophoresis and nucleotide sequencing techniques have led to the identification of molecular defects in the androgen receptor. The complexity of phenotypic presentation by affected subjects with the complete or partial forms of androgen insensitivity is represented by the heterogeneity of androgen receptor gene mutations which include deletions and point mutations, with the latter causing inappropriate splicing of RNA, premature termination of transcription and amino acid substitutions. The naturally occurring mutations in the androgen receptor of subjects with androgen insensitivity represent a base upon which we can increase our understanding of the structure and function of the androgen receptor in normal physiology and disease.

The gene for human eosinophil Charcot-Leyden crystal protein directs expression of lysophospholipase activity and spontaneous crystallization in transiently transfected COS cells

Expression of the gene encoding human eosinophil lysophospholipase, the Charcot-Leyden crystal (CLC) protein, was studied in transiently transfected COS cells. Recombinant CLC (rCLC) protein expression was demonstrated both by Western blot and radioimmunoassay inhibition analyses of transfected COS cell extracts and by immunofluorescent staining and ultrastructural immunogold analyses of intact cells. The rCLC protein was immunochemically indistinguishable from native eosinophil-derived CLC protein, and each transfected COS cell expressed approximately 11 pg of rCLC protein as determined by radioimmunoassay and assessment of transfection efficiency. Immunofluorescent microscopy and ultrastructural immunogold analyses localized rCLC protein to the nucleus, cytoplasm, and plasma membrane of COS cells. Lysates from transfected COS cells producing CLC protein expressed significant lysophospholipase activity. Furthermore, rCLC protein expressed in COS cells spontaneously formed the distinctive intracytoplasmic and intranuclear hexagonal bipyramidal crystals characteristic of the native eosinophil and basophil-derived protein. Expression of the CLC gene confirms the authenticity of the CLC cDNA, the expression of lysophospholipase activity by this unique eosinophil and basophil constituent, and will facilitate the routine purification of the active enzyme for in vitro and animal model studies of its role (or roles) in eosinophil and basophil associated allergic inflammation and eosinophil-parasite interactions.

Abolition with chloramine-T of inactivation in barnacle muscle fibers results in stimulation of the ouabain-insensitive sodium efflux

The hypothesis that chloramine-T stimulates the basal Na+ efflux in barnacle fibers as the result of the entry of trigger Ca2+ into the myoplasm from the bathing medium was examined in this study. Two reasons for doing so can be given. One is that the oxidant is known to abolish inactivation in sodium and potassium channels. The other is that L-type Ca2+ channels are present in barnacle fibers, and an increase in internal free Ca2+ in these fibers is known to stimulate the Na+ efflux, particularly in ouabain-poisoned fibers. The results of the experiments are as follows: (i) Chloramine-T exerts a biphasic effect on the Na+ efflux: inhibition is followed by stimulation, the threshold concentration being 10(-5) M. This is also found to be the threshold concentration for shortening of these fibers. (ii) The kinetics of the inhibitory effect resemble those of ouabain. (iii) Ouabain is without effect on the stimulatory phase caused by chloramine-T. (iv) Application of chloramine-T after the full effect of 10(-4) M-ouabain is reached elicits solely a stimulatory response. (v) The dose-response curves for the stimulatory action of chloramine-T in unpoisoned and ouabain-poisoned fibers are alike except that the threshold concentration is less than 10(-5) M in poisoned fibers. (vi) Basal light emission from unpoisoned and ouabain-poisoned fibers loaded with the photoprotein, aequorin, some 60 min beforehand increases as soon as they are exposed to 10(-4) M chloramine-T. The response recorded in unpoisoned fibers is monophasic and usually transitory, whereas it is multiphasic and usually sustained in ouabain-poisoned fibers. (vii) The dose-response curve for chloramine-T shows a shift to the left in poisoned fibers. (viii) The magnitude of the rise in light emission depends on the external Ca2+ concentration. A rise fails to take place in the nominal absence of external Ca2+. Taken together, these results support the above hypothesis that chloramine-T causes the entry of trigger Ca2+ into the myoplasm from the outside and provide evidence that stimulation of the Na+ efflux is associated not only with this event but also with a reduced Na+ gradient resulting from inhibition of the membrane Na+/K(+)-ATPase system by the oxidant. Thus, the suggestion put forward is that this oxidant promotes reverse Na+/Ca2+ exchange and is able to exert multiple effects on membrane transport.

[An epidemiological investigation of outbreak of measles among temporarily living people in Shenyang]

This paper reported an outbreak of measles occurred in a factory of Heping District in Shenyang in March 1989. All of the six diagnosed cases were temporarily workers, which represented 15 percent (6/40) of total workers. No secondary cases were detected. The results of epidemiological and laboratory analysis showed that this outbreak was caused by an imported case, and only spread in temporarily workers. Furthermore, we discussed that under the condition that measles incidence was limited under control level, even imported cases could not cause epidemic of measles. So, it is indicated that the flowing people can easily cause accumulation of susceptible people in cities, which may result in outbreak of some infectious diseases.

Influence of recombinant human interleukin (IL)-7 on disease progression in mice infected with Friend virus complex

Recombinant human (rhu) IL-7 was evaluated for its influence on disease progression in mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC). DBA/2 mice were injected i.v. with FVC, and then treated s.c. with rhuIL-7. IL-7 significantly prolonged survival time and decreased spleen focus-forming virus (SFFV) levels, expression of SFFV mRNA and SFFV protein production in FVC-infected mice. IL-7 did not appear to directly inactivate SFFV. Although both splenic weight and cellularity in FVC-infected mice treated with IL-7 were higher than those of normal mice, they were respectively 58% and 66% lower than those of the untreated FVC-infected mice. NK-cell activity was substantially lower in FVC-infected mice than in normal mice, while IL-7 restored NK-cell activity to normal levels. IL-6 and IFN-gamma levels were markedly reduced in FVC-infected mice compared to normal mice, but treatment of FVC-infected mice with IL-7 restored these cytokine levels. While the actual mechanisms of these effects are not yet known, the results suggest the potential therapeutic efficacy of IL-7 for certain hematopoietic and viral disorders, possibly mediated through an action on accessory cells and cytokine production.

Isolation of crt mutants constitutive for transcription of the DNA damage inducible gene RNR3 in Saccharomyces cerevisiae

Ribonucleotide reductase is an essential enzyme that catalyzes the rate limiting step for production of the deoxyribonucleotides required for DNA synthesis. It is encoded by three genes, RNR1, RNR2 and RNR3, each of which is inducible by agents that damage DNA or block DNA replication. To probe the signaling pathway mediating this DNA damage response, we have designed a general selection system for isolating spontaneous trans-acting mutations that alter RNR3 expression using a chromosomal RNR3-URA3 transcriptional fusion and an RNR3-lacZ reporter plasmid. Using this system, we have isolated 202 independent trans-acting crt (constitutive RNR3 transcription) mutants that express high levels of RNR3 in the absence of DNA damaging agents. Of these, 200 are recessive and fall into 9 complementation groups. In some crt groups, the expression of RNR1 and RNR2 are also elevated, suggesting that all three RNR genes share a common regulatory pathway. Mutations in most CRT genes confer additional phenotypes, among these are clumpiness, hydroxyurea sensitivity, temperature sensitivity and slow growth. Five of the CRT genes have been identified as previously cloned genes; CRT4 is TUP1, CRT5 is POL1/CDC17, CRT6 is RNR2, CRT7 is RNR1, and CRT8 is SSN6. crt6-68 and crt7-240 are the first ts alleles of RNR2 and RNR1, respectively, and arrest with a large budded, cdc terminal phenotype at the nonpermissive temperature. The isolation of crt5-262, an additional cdc allele of POL1/CDC17, suggests for the first time that directly blocking DNA replication can provide a signal to induce the DNA damage response. crt2 mutants show a defect in basal level expression of RNR1-lacZ reporter constructs. These are the first mutants isolated in yeast that alter the regulation of DNA damage inducible genes and the identification of their functions sheds light on the DNA damage sensory network.