Hemodynamic studies in DOCA-salt hypertensive rats after opening of an arteriovenous fistula

We determined the cardiovascular responses in normal and deoxycorticosterone acetate (DOCA)-salt hypertensive rats with reduced total peripheral resistance due to an arteriovenous (a-v) fistula. Animals were divided into four groups: control, fistula, DOCA-salt, and DOCA-salt fistula. The fistula was made by anastomosing the aorta and vena cava below the renal arteries. Four weeks after the creation of the fistula both DOCA-salt and DOCA-salt fistula animals received DOCA and salt for 6-8 wk. At the end of 10-12 wk we measured mean arterial pressure, cardiac output, tissue flows, and right atrial pressure. Flow measurements using radioactive microspheres were made in anesthetized animals. Cardiac index (CI) was 202% higher in the fistula group than in the control animals and 165% higher in the DOCA-salt fistula than in the DOCA-salt animals. There was no difference in cardiac output between the control and DOCA-salt animals. The increase in cardiac output was due to the fistula flow as evidenced by a significant increase in the number of microspheres in the lung. Mean arterial pressure was 115 +/- 4 mmHg (control) and 108 +/- 5 mmHg (fistula) in non-DOCA rats but increased in both DOCA groups, 159 +/- 3 mmHg (DOCA-salt) and 145 +/- 5 mmHg (DOCA-salt fistula). Right atrial pressure was increased above control in both fistula animals but was normal in DOCA-salt animals. Total peripheral resistance (TPR) was higher than control in DOCA-salt animals, but TPR in both the fistula and DOCA-salt fistula animals was lower than control.(ABSTRACT TRUNCATED AT 250 WORDS)

Susceptibility of inbred strains of mice to murine AIDS (MAIDS) correlates with target cell expansion and high expression of defective MAIDS virus

Murine AIDS (MAIDS) is readily induced by the Duplan strain of defective murine leukemia virus in susceptible C57BL/6 mice. To identify mouse strains resistant to MAIDS, and to understand the genetic factors controlling susceptibility to the disease, we screened more than 20 inbred strains of mice for their susceptibility to MAIDS. For this study, mice of the Fv-1n/n, Fv-1b/b, or Fv-1n/b genotype were inoculated with stocks of defective MAIDS virus pseudotyped with N-tropic, B-tropic, or NB-tropic helper murine leukemia virus, respectively. Strains could be classified as susceptible, resistant, or moderately resistant. None of the individual H-2 haplotypes examined appears to explain resistance to MAIDS by itself. However, a very good correlation between the susceptibility or resistance phenotype and the presence or absence of defective proviral DNA and RNA in the spleen of these animals was found. Since the presence of defective proviral DNA and RNA reflects the oligoclonal proliferation of the cells infected by the defective MAIDS virus, our results strongly suggest that this target cell expansion is genetically controlled and is necessary and perhaps even sufficient for the development of the disease.

Hemodynamic changes in rats after opening an arteriovenous fistula

Time course of multiple hemodynamic changes in rats after opening an AV fistula was assessed. The fistula was made in male Sprague-Dawley rats by anastomosing the aorta and vena cava below the renal arteries. At 1 h (1H), 1 day (1D), 1 wk (1W) and 5 wk (5W) in sham controls or after opening an AV fistula, we measured cardiac output (CO) and tissue flows by using radioactive microspheres. The flow of microspheres to the lungs was used as a measure of shunt flow. In the fistula animals this lung flow (fistula flow) was 50-77% of the CO compared with 1-3% in the control animals. Cardiac index in the fistula animals increased by 40, 107, 129, and 307% compared with the respective control animals in the consecutive time groups. Systemic flow, tissue flows, and mean arterial blood pressure (MAP) in the fistula animals in the 1H and 1W groups were significantly decreased below control values, but each of these variables returned to control levels after 5W. Hematocrit (Hct) significantly decreased, whereas right atrial pressure (RAP) gradually increased over the experimental period. These two observations suggest retention of fluid. Plasma renin activity increased in the 1H animals but returned to control in the 1D animals. Atrial natriuretic peptide (ANP) gradually increased throughout the 5 wk from 86 +/- 22 (1H) to 709 +/- 217 pg/ml (5W). The increase in ANP correlated with the increase in RAP. Calculated total peripheral resistance in fistula animals was significantly decreased throughout the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

[Inhibition of photosensitization of morin on DNA synthesis of ascites hepatoma cells]

Morin (0.012, 0.12, 1.2, 12.0 micrograms.ml-1) significantly inhibited the DNA synthesis of ascitic hepatoma (AH) cells. The inhibition of DNA synthesis and cell mortality was dependent on its concentrations as well as the illumination time. Photosensitization of morin was not due to 1O2 and O2-, but closely related to OH. and H2O2. The mechanism of the inhibition may be attributed to the damage of DNA replication template.

The majority of cells infected with the defective murine AIDS virus belong to the B-cell lineage

Murine AIDS (MAIDS) is caused by a defective retrovirus which encodes a gag fusion protein (Pr60gag). We previously reported that this virus induced an oligoclonal proliferation of infected cells and suggested that this cell expansion was an important event in the pathogenesis of MAIDS. To identify these target cells, we constructed novel defective viruses whose genomes could be detected with specific probes. Helper-free stocks of these viruses induced MAIDS. Using in situ hybridization and immunocytochemistry and Southern analysis, we found that most infected cells belong to the B-cell lineage. Transformation of these B cells appears to be the primary event responsible for the development of immunodeficiency. This animal model may be relevant to our understanding of AIDS, of the immunodeficiencies associated with B-cell lymphoproliferative disorders, and of the role of B-cell proliferation and transformation in the effects of superantigens, since Pr60gag appears to be a superantigen.

Early dropouts from psychotherapy

Ninety-six patients requesting psychotherapy were studied prospectively at the time of screening interview by four senior psychiatrists using a variation on Luborsky's Helping Alliance questionnaire and the Osgood Semantic Differential. Significant differences were found at the time of screening between early dropouts and continuers, among screeners' rate of early dropouts, and among patients' perceptions of screeners. The screener with a high early dropout rate was seen as being more passive and less potent, and offering less new understanding than other screeners. Patients who dropped out early experienced a less strong helping alliance, felt they gained less new understanding, liked the clinician less well, felt less well liked and less respected, and saw the interviewer as more passive and psychotherapy as less potent than did continuers.

A generic intron increases gene expression in transgenic mice

To investigate the role of splicing in the regulation of gene expression, we have generated transgenic mice carrying the human histone H4 promoter linked to the bacterial gene for chloramphenicol acetyltransferase (CAT), with or without a heterologous intron in the transcription unit. We found that CAT activity is 5- to 300-fold higher when the transgene incorporates a hybrid intron than with an analogous transgene precisely deleted for the intervening sequences. This hybrid intron, consisting of an adenovirus splice donor and an immunoglobulin G splice acceptor, stimulated expression in a broad range of tissues in the animal. Although the presence of the hybrid intron increased the frequency of transgenics with significant CAT activity, it did not affect the integration site-dependent variation commonly seen in transgene expression. To determine whether the enhancement is a general outcome of splicing or is dependent on the particular intron, we also produced equivalent transgenics carrying the widely used simian virus 40 small-t intron. We found that the hybrid intron is significantly more effective in elevating transgene expression. Our results suggest that inclusion of the generic intron in cDNA constructs may be valuable in achieving high levels of expression in transgenic mice.

Characterization of the gag/fusion protein encoded by the defective Duplan retrovirus inducing murine acquired immunodeficiency syndrome

Murine acquired immunodeficiency syndrome is induced by a defective retrovirus. Sequencing of this defective viral genome revealed a long open reading frame which encodes a putative gag/fusion protein, N-MA-p12-CA-NC-COOH, (D. C. Aziz, Z. Hanna, and P. Jolicoeur, Nature (London) 338:505-508, 1989). We raised a specific antibody to the unique p12 domain of this gag fusion precursor, Pr60gag. We found that Pr60gag was indeed encoded by the defective viral genome both in cell-free translation reticulocyte extracts and in infected mouse fibroblasts. Pr60gag was found to be myristylated, phosphorylated, and attached to the cell membrane, like other helper murine leukemia virus (MuLV) gag precursors. Pr60gag was not substantially cleaved within the nonproducer cells and was not released from these cells. However, in the presence of helper MuLV proteins, it formed phenotypically mixed particles. In these particles, Pr60gag was only partially cleaved. In helper MuLV-producing cells harboring the defective virus, a gag-related p40 intermediate was generated both intracellularly and extracellularly. In these cells, Pr60gag appeared to behave as a dominant negative mutant, interfering with proper cleavage of helper Pr65gag. Our data indicate that Pr60gag is a major (and possibly the only) gene product of the defective murine acquired immunodeficiency syndrome virus and is likely to harbor some determinants of pathogenicity of this virus.

Selective effect of castration on the anterior pituitary VIP receptor of male rats

We investigated the effect of surgical castration of male rats on the binding of [Tyr(125I)10]VIP to receptors on the anterior pituitary gland, superior mesenteric artery, brain, liver, and prostate gland. In anterior pituitary membranes the maximum number of VIP binding sites was increased whereas binding affinity was decreased 24 hours following castration. In particular, the high affinity equilibrium dissociation constant (KD) increased from 0.13 +/- 0.02 nM (mean +/- SEM) to 0.67 +/- 0.07 nM and the maximum number of high affinity binding sites (Bmax) increased from 71 +/- 9 to 470 +/- 112 fmol/mg protein. No significant change was observed in the other tissues. Anesthesia or sham operation did not alter the anterior pituitary VIP receptor binding parameters. The changes in the VIP receptor 24 hours after castration were prevented by prior injection of testosterone. These findings demonstrate tissue-selective alterations to the anterior pituitary VIP receptor by castration that are likely mediated by withdrawal of testosterone.

Intravenous infusions of ifosfamide/mesna and perturbation of warfarin anticoagulant control

We report three patients who had serious disturbance of anticoagulant control while receiving ifosfamide/mesna-containing cytotoxic chemotherapy in association with warfarin. In view of the likely biological potentiation of warfarin by ifosfamide/mesna, close monitoring of anticoagulant control should be performed during the co-administration of these drugs.

Functional elements of the steroid hormone-responsive promoter of mouse mammary tumor virus

Transcription from the promoter of mouse mammary tumor virus is subject to induction by several classes of steroid hormones as well as to repression by a negative regulatory element present in the long terminal repeats of proviral DNA. In order to characterize the functional elements of the promoter that in some way must respond to these regulatory signals, a number of promoter mutations were constructed, including a set of linker-scanning mutations across the entire promoter region. Analysis of these mutated promoters with a transient-transfection assay defined at least three mutation-sensitive promoter elements that are required for both basal and hormone-induced transcription. One mutation-sensitive region contains a TATA element located at approximately position -30 with respect to the start of transcription. A second mutation-sensitive region contains two 10-base-pair direct repeats located between positions -60 and -38, within which are embedded three copies of octamer-related sequences; complete disruption of this region of the promoter leads to a more severe decrease in transcription than do any of the linker-scanning mutations, suggesting that the repeated sequences may be at least partially functionally redundant. Gel electrophoresis mobility shift assays were used to demonstrate specific binding of a nuclear protein to this region of the promoter. A third mutation-sensitive region contains a binding site for nuclear factor 1 (NF-1) located between positions -77 and -63. Site-directed mutations in the NF-1-binding site which increase the apparent affinity of NF-1 for the promoter in vitro do not decrease the hormone dependence of transcription, suggesting that transcriptional activation mediated by steroid hormone-receptor complexes cannot be explained by facilitation or stabilization of the interaction of promoter sequences with NF-1 and consistent with the idea that binding of NF-1 is not rate determining in transcription from the mouse mammary tumor virus promoter. None of the promoter mutations functionally separates basal from glucocorticoid-induced transcription, suggesting that hormone induction does not make the promoter independent of any of the DNA-binding factors required for its basal activity.

PHI preferentially binds to VIP receptors in normal rat tissues

Vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are homologous neuropeptides with parallel biological actions. These similarities raise the question whether VIP and PHI have common or distinct mechanisms of action, including receptors. The present study attempted to distinguish specific binding sites for VIP and PHI in normal rat tissues using the homologous radioligands [Tyr(125I)10]VIP and [Tyr(125I)10]rat PHI. In rat brain, anterior pituitary, and liver membranes both radioligands identified a VIP-preferring receptor. Rat PHI had less than 10% the binding potency of VIP in these tissues irrespective of which radioligand was used. In rat uterine membranes [Tyr(125I)10]VIP bound to a receptor with approximately 100 times greater affinity for VIP over PHI. No specific binding of [Tyr(125I)10]rat PHI to rat uterus could be demonstrated. In conclusion, these results support the predominance of VIP-preferring receptors as opposed to PHI-preferring receptors in normal rat brain, anterior pituitary, liver and uterus.

[Variation of cAMP in cerebral cortex and hippocampus in seizure mice induced by coriaria lactone]

To study the relationship between cAMP and epilepsy, we investigated the effects of coriaria lactone (CL) on the levels of cAMP in cerebral cortex and hippocampus. Fifty normal WC1 mice were divided into 5 groups. All groups were injected with CL (2.5 mg/kg, i.m.), except the control group which was injected with NS. The concentrations of cAMP were measured after the animals had been immersed in liquid nitrogen to die at different phases of seizure development induced by CL (before seizures, in mild seizures, during severe seizures, and after severe seizures). The results indicated that the levels of cAMP in both cerebral cortex and hippocampus were significantly increased (1.73-fold and 1.33-fold) in severe seizure, and they continuously increased (1.85-fold and 1.45-fold) after severe seizures. On the other hand, no changes of cAMP were observed in mild seizures and before seizures. These data suggested that accumulation of cAMP is probably the result of seizure activity rather than the cause of seizure.

Effects of hepatocarcinogenic initiators on aldehyde dehydrogenase gene expression in cultured rat hepatic cells

The effects of certain in vivo inducers of tumor-associated aldehyde dehydrogenase (aldehyde:NAD+ oxidoreductase, EC 1.2.1.3; ALDH) activity on the expression of tumor-associated ALDH (T-ALDH) in vitro have been investigated using cultured rat hepatocytes and hepatoma cell lines. Two distinct groups of T-ALDH inducers have been identified. Three hepatocarcinogenic initiators 2-acetylaminofluorene, diethylnitrosamine and ethionine, which cause changes in T-ALDH in vivo, do not induce T-ALDH activity in cultured rat hepatocytes or hepatoma cell lines following either short-term or long-term exposures. In contrast, polycyclic aromatic hydrocarbons, such as 3-methylcholanthrene, benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene, induce an immediate increase of T-ALDH activity in both cultured rat hepatocytes and hepatoma cell lines. Synthesis and degradation rates of T-ALDH mRNA and protein have also been determined. The synthesis of T-ALDH protein is coupled with the increased synthesis of T-ALDH mRNA when the T-ALDH gene is constitutively expressed or activated by an inducer. Both T-ALDH mRNA (t1/2 = 25 - 34 h) and protein (t1/2 = 88 - 95 h) in high T-ALDH activity cell lines or low-activity cell lines treated with an inducer are relatively stable. Combined with previous studies, the results suggest that at least two different mechanisms are involved in T-ALDH gene expression; events occurring during initiation as well as during promotion appear to be involved in the genetically stable changes in T-ALDH gene expression which occur in vivo. The results also indicate that the lack of T-ALDH activity in normal hepatocytes or low-activity hepatoma cell lines is due to repression of the T-ALDH gene rather than to the differential stability of T-ALDH mRNA or protein.

Selectivity for binding of peptide analogs to vascular receptors for vasoactive intestinal peptide

The structure-activity relationships for vasoactive intestinal peptide (VIP) receptor binding were studied using N-terminally modified VIP analogs. VIP fragments, and VIP receptor antagonists. Tissue sources included bovine coronary artery, rat mesenteric artery, rat pituitary, rat brain synaptosomes, and rat liver. Experimental conditions for receptor binding were maintained as near to identical as possible. The competitive binding curves for VIP analogs were similar in the bovine and rat vascular preparations. However, appreciable differences were observed between the vascular and other preparations. The vascular receptors discriminated between [D-His1]VIP and [Phe1]VIP, whereas the receptors in other tissues did not. The greatest selectivity was found for [D-Ala4]VIP, which was among the lowest affinity analogs tested on the vasculature but among the highest affinity analogs in the other preparations. The rank orders of analog potencies were comparable for the rat brain and pituitary receptors. The rat liver VIP receptor differed from its counterpart in brain and pituitary predominantly by discriminating between [D-Phe2]VIP and [D-Arg2]VIP. The two VIP receptor antagonists bound weakly and nonselectively to all receptor preparations. Integrity of the full VIP molecule was necessary for full potency of binding to the vascular receptor. We conclude that the vascular VIP receptor possesses recognition properties that are distinct from those for VIP receptors in liver, pituitary, or brain.

Outer hair cells as potential targets of inflammatory mediators

Inner ear sequelae with temporary or permanent sensorineural hearing loss can result from inflammatory processes in the middle ear. Loss of outer hair cells in the base of the cochlea has been noted in otitis media, but it is not known how this damage occurs. Evidence supports the permeability of the round window membrane to substances mediating inflammation in the middle ear, and the presence of white blood cells has been reported in the perilymph. In the present study, the potential cytotoxic effects of two representative inflammatory mediators, endotoxin and free radicals, have been evaluated by use of short-term culture of isolated outer hair cells from the guinea pig cochlea model. Incubation with endotoxins from two gram-negative pathogens increased the rate of hair cell death fourfold to sixfold. Free radicals (generated by exposure of cells to UV light or by excitation of intracellular fluorescent dyes) produced morphologic damage to hair cells within 60 seconds. These latter effects were delayed by addition of free-radical scavengers. It is concluded that inflammatory mediators are cytotoxic to hair cells and therefore are potentially ototoxic if permeating the round window membrane.

[Effect of disintegrating method on quantity extracted and constituents of essential oil in fructus Aurantii]

The quantity extracted, constituents and their contents in essential oil from Fructus Aurantii were obviously influenced by the method of disintegration. Among stamp breaking in water, crusher-run and miling, stamp breaking in water is the best method. The advantage of this method lies in higher percentage recovery of the oil and smaller loss in volatilization.

pH-dependent spectral and kinetic properties of cytochrome c peroxidase: comparison of freshly isolated and stored enzyme

The effect of long-term storage on the electronic absorption spectrum and the kinetic properties of cytochrome c peroxidase has been investigated. No detectable differences were observed between freshly isolated enzyme and enzyme stored below -20 degrees C, in the crystalline state, for up to 41 months. The electronic absorption spectrum and the rate of the enzyme-hydrogen peroxide reaction are essentially independent of pH in 0.1 M potassium phosphate buffers for both fresh and stored enzyme. In buffers containing KNO3, the absorption spectrum and the kinetic properties of both fresh and stored enzyme vary with pH, consistent with the titration of an ionizable group with an apparent pKa of 5.5 +/- 0.1. The differences between phosphate- and nitrate-containing buffers are attributed to specific ion effects. In KNO3-containing buffers, the high-pH form of the enzyme reacts rapidly with hydrogen peroxide while the low-pH form is unreactive. Evidence is presented which indicates that both the low-pH and high-pH forms of the enzyme in KNO3-containing buffers are 5-coordinate, high-spin Fe(III) species.

[Effect of wuwei chongji on the mechanical activity of the stomach of SD rats in vivo]

The effect of Wuwei Chongji on the mechanical activity of stomach of SD rats was studied using fixed point method. The experimental results showed that Wuwei Chongji increased the amplitude and frequency of contraction of stomach in rats, and was able to adjust the high and low tension of contraction of stomach. The contraction of the stomach was not influenced by Natrii Chloridi (0.9%) at the same dose.

Measurement of the refractive index and thermal refractive index coefficients of Nd:YAP crystal

The principal refractive indices of yttrium aluminate crystal doping with 1-wt.% neodymium (Nd:YAP) have been measured by a minimum deviation method for the wavelengths 0.5398, 0.6328, and 1.0795 microm in the temperature range of 289-435 K. The thermal refractive index coefficients have been obtained at these wavelengths, and they are all positive and slightly decrease with increased wavelength. The constants of the single term Sellmeier equation are also given for the 273-420 K temperature range. These constants are in linear relationship with temperature in the 4 x 10(-3) error range.