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.

Ribonucleotide reductase: regulation, regulation, regulation

Ribonucleotide reductase (RNR) catalyses the rate limiting step in the production of deoxyribonucleotides needed for DNA synthesis. It is composed of two dissimilar subunits, R1, the large subunit containing the allosteric regulatory sites, and R2, the small subunit containing a binuclear iron center and a tyrosyl free radical. Recent isolation of the mammalian and yeast RNR genes has shown that, in addition to the well documented allosteric regulation, the synthesis of the enzyme is also tightly regulated at the level of transcription. The mRNAs for both subunits are cell-cycle regulated and, in yeast, inducible by DNA damage. Yeast encode a second large subunit gene, RNR3, that is expressed only in the presence of DNA damage. This regulation is thought to provide a metabolic state that facilitates DNA replicational repair processes.

Properties of the pacemaker current (If) in latent pacemaker cells isolated from cat right atrium

1. Single latent pacemaker cells were isolated from the Eustachian ridge of cat right atrium using Langendorff perfusion and enzyme dispersion techniques. Whole-cell patch-clamp techniques were used to study the hyperpolarization-activated inward current (I(f)). 2. All cells studied beat rhythmically. Pacemaker activity was recorded in the voltage range -68 +/- 1 to -54 +/- 2 mV and its cycle length was 901 +/- 67 ms (72 +/- 5 beats min-1) at 34-36 degrees C. Cells were elongated with tapered ends, and appeared bent or crinkled without obvious striations. Mean cell diameter and length were 7.4 +/- 0.5 microns and 93.1 +/- 5.9 microns, respectively (n = 15). Input resistance and total membrane capacitance were 2.2 +/- 0.2 G omega and 27.8 +/- 3.1 pF, respectively. 3. Hyperpolarizing clamp steps more negative than -50 mV elicited a time-dependent increasing inward current that was maximally activated at -120 mV. Activation of I(f) was well within the pacemaker voltage range. Half-maximal activation voltage and slope factor were calculated, using a Boltzmann function, to be -80.5 mV and 8.4, respectively. 4. The fully activated current-voltage (I-V) relationship was approximately linear at voltages more negative than -30 mV and showed outward rectification at more positive voltages. The reversal potential of I(f) was -26 mV and the fully activated conductance was 1.75 +/- 0.14 nS (n = 21). Caesium (2 mM) blocked I(f) at voltages more negative than the reversal potential. Reducing extracellular Na+ or K+ shifted the reversal potential more negative, and increasing extracellular K+ exerted the opposite effect. Reducing extracellular Na+ decreased I(f) amplitude and the slope of the fully activated I-V relationship, and elevated extracellular K+ increased I(f) amplitude and the slope of the fully activated I-V relationship. 5. Some pacemaker cells exhibited a short delay in the onset of I(f) activation whereas other pacemaker cells exhibited little, if any, delay in activation. I(f) currents exhibiting no delay in activation were best fitted by a single exponential function with a mean time constant of 3.20 +/- 1.03 s at -70 mV (n = 4). 6. A nystatin-permeabilized patch recording method was used to record spontaneous pacemaker action potentials and I(f) from the same pacemaker cell. Caesium (2 mM) inhibited I(f) by more than 90% (at -70 mV), and decreased the slope of diastolic depolarization, resulting in a 48 +/- 5% decrease in spontaneous rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of cell surface receptors for murine macrophage inflammatory protein-1 alpha

We have produced recombinant proteins for a cytokine, L2G25BP (macrophage inflammatory protein-1 alpha) (MIP-1 alpha). By using the recombinant protein (rMIP-1 alpha), receptors for MIP-1 alpha were identified on Con A-stimulated and unstimulated CTLL-R8, a T cell line, and LPS-stimulated RAW 264.7, a macrophage cell line. The 125I-rMIP-1 alpha binds to the receptor in a specific and saturable manner. Scatchard analysis indicated a single class of high affinity receptor, with a Kd of approximately 1.5 x 10(-9) M and approximately 1200 binding sites/Con A-stimulated CTLL-R8 cell and a Kd of 0.9 x 10(-9) M and approximately 380 binding sites/RAW 264.7 cell. 125I-rMIP-1 alpha binding was inhibited by unlabeled rMIP-1 alpha in a dose-dependent manner, but not by IL-1 alpha or IL-2. rMIP-1 alpha inhibited the proliferation of unstimulated CTLL-R8 cells. Rabbit anti-rMIP-1 alpha antibodies blocked the growth-inhibitory effect of the rMIP-1 alpha on CTLL-R8 cells.

Identification of cell surface receptors for murine macrophage inflammatory protein-1 alpha

We have produced recombinant proteins for a cytokine, L2G25BP (macrophage inflammatory protein-1 alpha) (MIP-1 alpha). By using the recombinant protein (rMIP-1 alpha), receptors for MIP-1 alpha were identified on Con A-stimulated and unstimulated CTLL-R8, a T cell line, and LPS-stimulated RAW 264.7, a macrophage cell line. The 125I-rMIP-1 alpha binds to the receptor in a specific and saturable manner. Scatchard analysis indicated a single class of high affinity receptor, with a Kd of approximately 1.5 x 10(-9) M and approximately 1200 binding sites/Con A-stimulated CTLL-R8 cell and a Kd of 0.9 x 10(-9) M and approximately 380 binding sites/RAW 264.7 cell. 125I-rMIP-1 alpha binding was inhibited by unlabeled rMIP-1 alpha in a dose-dependent manner, but not by IL-1 alpha or IL-2. rMIP-1 alpha inhibited the proliferation of unstimulated CTLL-R8 cells. Rabbit anti-rMIP-1 alpha antibodies blocked the growth-inhibitory effect of the rMIP-1 alpha on CTLL-R8 cells.

[Improvement of memory in mice by extracts from leaves of Ginkgo biloba L]

The study has shown that the extracts from leaves of Ginkgo biloba can significantly improve the NaNO2 and scopolamine induced impaired memory in mice. The potency of the ethanolic extract is greater than that of the aqueous extract. The ethanolic extract acts favorably on the memory function of normal animals. Both extracts help to prolong the survival time of mice receiving 200 mg/kg(ip)NaNO2.

[Light and scanning electron microscopic study on portal circulation of the pancreas in the monkey]

The channel of microcirculation in the exocrine and endocrine parts of the pancreas in 20 monkeys (Macaca Mulatta) were studied by scanning electron microscopy (SEM) and light microscopy (LM). The results revealed that there are portal circulations between the endocrine and exocrine parts in the pancreas of monkey. The direction of the blood flow is from the endocrine to the exocrine part: arteriole----sinusoid of the islet----portal vessel----acinar capillaries----venule. There are "insulo-insular portal system" and "convergent insulo-acinar portal system" in pancreas of these monkeys. This is for the first time reported. The functional and clinical significances of pancreatic portal circulation are discussed.

Relationship between naturally occurring human antibodies to casein and autologous antiidiotypic antibodies: implications for the network theory

Previous studies on human autologous antiidiotypes have been based largely upon analyses of autoimmune disease. We have previously described polyclonal, naturally occurring human autoantibodies directed against antibodies with specificity toward bovine casein in the sera of IgA-deficient humans. In order to define this system more exactly we have not produced two murine monoclonal antibodies directed against bovine milk kappa-casein to use as clonal tools to identify specific antiidiotypes in these human sera. Kappa-casein is an important part of the casein micelle in milk and cheese; in addition to being an important immunogen for man, kappa-casein is known to have conserved amino acid sequence and two antigenic epitopes. Data presented here show that the serum of up to 74% of IgA-deficient and 10% of normal humans have specific autologous antiidiotypes in their serum which bind to monoclonal antibodies directed to bovine kappa-casein. These human antibodies [intact or F(ab)'2] can be blocked from binding to the monoclonal anti-kappa-caseins by pure bovine kappa-casein or the kappa-casein peptide fragment. In contrast to previous studies in autoimmune disease, serum levels of the autoantiidiotypes were directly proportional to the level of IgG antibody to bovine kappa-casein. These observations suggest that continual exposure to a ubiquitous dietary antigen may produce an antigen driven system in which stimulation of both Ab1 and Ab2 occurs in concert.

The nature of the redshift and directly observed quasar statistics

The nature of the cosmic redshift is one of the most fundamental questions in modern science. Hubble's discovery of the apparent Expansion of the Universe is derived from observations on a small number of galaxies at very low redshifts. Today, quasar redshifts have a range more than 1000 times greater than those in Hubble's sample, and represent more than 100 times as many objects. A recent comprehensive compilation of published measurements provides the basis for a study indicating that quasar observations are not in good agreement with the original predictions of the Expanding Universe theory, but are well fit by the predictions of an alternative theory having fewer adjustable parameters.

[Influences of new synthetic drug vesnarinone on circulatory and respiratory function of dogs]

The purpose of this study was to investigate the influences of vesnarinone, newly synthesized in the School of Pharmacy, West China University of Medical Sciences in 1985, on the circulatory and respiratory functions of dogs. Eight dogs were anesthetized with 3% sodium pentobarbital. Vesnarinone (2 mg/kg), dimethyl sulphoxide (the solvent which was needed to prepare solution of OPC-8212), and 0.9% NaCl (normal control) was given separately according to the arrangement of Latin square. The ECG, blood flow, blood pressure and respiration were measured and recorded for 1-15 minutes. Vesnarinone increased the blood flow in the common carotid artery with no significant changes in blood pressure, heart rate, or respiration. These results suggest that OPC-8212 has positive inotropic effect but no effect on the heart rate in anesthetized dogs.

[Determination of trace chloride and sulfate in drugs by ion chromatography]

Chloride and sulfate in magnesium trisilicate, activated charcoal, vesnarinone and bendazac were determined by the IC conductimetric detection. Analysis were performed by using a separating column (100 x 6 mm i.d.) packed with anion exchanger and with a stripper column (100 x 6 mm i.d.); 1.4 mmol/L Na2CO3 and 1.4 mmol/L Na2CO3-0.75 mmol/L NaHCO3 were used as eluents respectively. The peak height was linear with concentration from 10(-6) to 10(-3) mol/L for Cl- and from 10(-5) to 10(-3) mol/L for SO4(2-). Results showed no significant difference as compared with those determined by the CHP (1985) and CHP (1990) appendices methods. The IC method is specific, sensitive, simple and rapid.

l-tetrahydropalmatine increases leucine enkephalin levels in corpus striatum of rats

The effect of chronic l-tetrahydropalmatine (l-THP) administration on the level of leucine enkephalin (Leu-Enk) in rat corpus striatum was studied. After l-THP sc injection once daily for 2 wk, the striatal Leu-Enk level was elevated dose-dependently. However, a single injection of l-THP failed to change the Leu-Enk level. When rats received sc Sch-23390, a selective D1 antagonist, 15 nmol.kg-1 tid for 2 wk, striatal content of Leu-Enk increased from 0.17 +/- SD 0.03 ng.mg-1 tissue in control group to 0.23 +/- SD 0.05 ng.mg-1 tissue in Sch-23390 group (n = 8, P less than 0.05). Sulpiride (Sul), a selective D2 antagonist, 140 mumol.kg-1 sc given bid for 2 wk had no significant effect on the striatal Leu-Enk content. The results suggested that the blockade of D1 receptors by l-THP might be responsible for the increase of the striatal Leu-Enk content in rat.

Clinical and experimental observations on treatment of peptic ulcer with wei yang an (easing peptic-ulcer) capsule

The therapeutic effects of peptic ulcer treated with cimetidine and Wei Yang An were compared clinically and experimentally by the double blind method. Results showed that the effects of the two are similar, but the long-term effect of Wei Yang An was better. Wei Yang An was also good for most cimetidine resistant ulcers, with few side effect. Animal experiment showed that Wei Yang An inhibited the ulcers.

An expert system for simulation of coronary heart disease risk factor interventions

The feasibility of using an expert system to support intervention studies within CRISPERS was investigated. A prototype expert system named CRISPERT was designed to accept user inputs, adjust the values to CRISPERS requirements, start a sequence of simulations, and analyze and interpret the results. The rule-based system was implemented using the expert system development language OPS5 combined with FORTRAN, as well as SAS procedures and DEC VMS system service routines. Results of initial tests suggest that using an expert system as an interface between users and CRISPERS is a viable approach. The development of CRISPERT facilitates the usability of CRISPERS for intervention studies of coronary heart disease.

Purification and characterization of calmodulin-dependent multifunctional protein kinase from smooth muscle: isolation of caldesmon kinase

Previously, it was reported that smooth muscle caldesmon is a protein kinase and is autophosphorylated [Scott-Woo, G.C., & Walsh, M.P. (1988) Biochem. J. 252, 463-472]. We separated a Ca2+/calmodulin-dependent protein kinase from caldesmon in the presence of 15 mM MgCl2. The Ca2+/calmodulin-dependent caldesmon kinase was purified by using a series of liquid chromatography steps and was characterized. The subunit molecular weight (MW) of the kinase was 56K by SDS gel electrophoresis and was autophosphorylated. After the autophosphorylation, the kinase became active even in the absence of Ca2+/calmodulin. The substrate specificity of caldesmon kinase was similar to the rat brain calmodulin-dependent multifunctional protein kinase II (CaM PK-II) and phosphorylated brain synapsin and smooth muscle 20-kDa myosin light chain. The purified kinase bound to caldesmon, and the binding was abolished in the presence of high MgCl2. Enzymological parameters were measured for smooth muscle caldesmon kinase, and these were KCaM = 32 nM, KATP = 12 microM, Kcaldesmon = 4.9 microM, and KMg2+ = 1.1 mM. Optimum pH was 7.5-9.5. The observed properties were similar to brain CaM PK-II, and, therefore, it was concluded that smooth muscle caldesmon kinase is the isozyme of CaM PK-II in smooth muscle.

Investigations of gas-phase lithium-peptide adducts: Tandem. mass spectrometry and semiempirical studies

Tandem mass spectrometry using a hybrid mass spectrometer of BEqQ geometry was used to investigate the gas-phase formation of the [An (+) Li - H)(+) ion from lithium-peptide adducts. High resolution mass measurements as well as precursor and product ion scans of five peptides indicate that one source of [An (+) Li - H) arises from [An (+) Li](+). Semiempirical calculations (MNOO) and metastable ion decomposition studies of the peptide Gly-Gly-Gly show that the lithium ion prefers to coordinate to the three internal carbonyls of the neutral molecule to give a species that is energetically more stable than the lithiated zwitterion by 305 kJ/mol. Theoretical and experimental evidence suggest that the monolithiated precursor ion population may be a distribution of structural isomers. (J Am Soc Mass Spectrom 1990, 1, 473-480).

Direct modeling of the output parameters of an optical recording

The relationship between the recorded bit size and write beam characteristics has been analyzed and calculated. A unified formulation for the reflectivity after recording is introduced, and a new analytical description of reflection contrast is established. The effects of read/write beam characteristics on the recording contrast are discussed. The theoretical analysis results are well supported by experiment results.

[Dynamic changes of lactate and pyruvate concentrations in human uterine fluid]

The main energy providing components of human uterine fluid are lactate and pyruvate. They have very low concentrations belonging to ppm and ppb levels respectively. The flow procedure of their-determination is designed adopting the Anion Exchange Chromatography method. The concentrating and analytical columns used are AG6 and AS6 respectively. A total of 59 women of child-bearing age with normal menstrual cycles were investigated for lactate and pyruvate concentration in the uterine fluid at different days during the menstrual cycle. Dynamic curves were plotted. The results obtained may give some hints on the appropriate composition of the culture medium used for in vitro fertilization and embryo transfer.

[Effect of a new positive inotropic agent (OPC-8212) on intracellular potential of isolated canine ventricular papillary muscle]

This study adopted intracellular microelectrode technic to observe the effect of OPC-8212 (Vesnarinone) on intracellular potential of isolated canine ventricular papillary muscle. The record and data processing were completed by computerized intellective instrument designed by ourselves. The results of intracellular record in 14 canine ventricular papillary muscle showed no significant change in the resting potential (RP), amplitude of action potential (APA) and maximum depolarize velocity of 0 phase (Vmax). But significantly increased whole duration of action potential (APT). The duration of repolarization to 1/3 (APD 1/3) and to 2/3 (APD 2/3) significantly increased too. The plateau phase raised. These results suggest that K+ permeability at resting myocardiac cell membrane may have not been effected by OPC-8212. Activation of the fast sodium channel may have not been effected too. The results of our studies also suggest that inward flow of Ca2+ increased. The delayed outward K+ (Ik) and the inward, rectifying K+ current (Ik1) possible decreased. Thus, the OPC-8212 might become a nonglucoside and noncatecholamine new positive inotropic drug.

Microvascular vasopressin effects during endotoxin shock in the rat

We have demonstrated decreased microvascular sensitivity to norepinephrine during endotoxin shock possibly related to reduced sympathetic receptor activity (Baker et al.: Circ Shock 12:165-176, 1984). The response to other vascular controls such as arginine vasopressin (AVP) may also be altered. Reactivity of the left cremaster muscle microvessels of pentobarbital anesthetized Wistar rats was studied using videomicroscopy and videodensitometry. Femoral arterial pressure (Pm), dose response curves of vessel diameters to topical arginine vasopressin (10(-15) to 10(-6) M), FITC-albumin mean transit times, and plasma velocities were obtained. Escherichia coli endotoxin (6 mg/kg i.v., LD100) was infused over a 1-hr period. Parameter measurements were repeated at 30 min and 90 min post-endotoxin. Both Pm and plasma velocities progressively decreased. Arteriolar constriction and the mean transit times of FITC-labeled albumin progressively increased. The threshold dose for AVP averaged 10(-9) M at control and decreased to 10(-14) M post-endotoxin. Venular diameters were not altered by AVP. The AVP antagonist did not alter the microvascular diameter response to endotoxin but did block the responses to topical and endogenous AVP since arterial pressure and flow velocity decreased at a significantly greater rate than in rats without antagonist. Plasma AVP levels were significantly increased by endotoxin. Reduced alpha adrenergic sensitivity may unmask the responsiveness to AVP or increase the sensitivity of AVP receptors. Increased endogenous AVP may require a smaller exogenous concentration of AVP for constriction.