Repair of calvarial nonunions by osteogenin, a bone-inductive protein

Efforts were taken to determine the dose of bovine osteogenin (OG) that would induce more bone than that induced by 20 mg of rat particulate demineralized bone matrix (DBM), the amount allowed by the confines of an 8-mm rat craniotomy defect. Dose-response studies were performed for demineralized bone matrix alone and osteogenin, partially purified from bovine demineralized bone matrix, plus rat insoluble collagenous bone matrix (M). Demineralized bone matrix alone (2.5, 5.0, 10, 20, or 40 mg) or osteogenin (0.0625, 0.125, 0.250, 0.50, or 1.0 mg) plus 25 mg insoluble collagenous bone matrix was implanted into the pectoralis muscle for 3, 5, and 7 weeks. Both materials induced time- and dose-dependent formation of bone. The three highest dosages of osteogenin (plus insoluble collagenous bone matrix) induced more bone than 20 mg demineralized bone matrix and seemed to accelerate bone repair. However, when implanted into the 8-mm rat craniotomy defect for 4 weeks, 20 mg demineralized bone matrix and 0.5 mg osteogenin (plus insoluble collagenous bone matrix) induced comparable amounts of bone. These results suggest different mechanisms for bone formation in heterotopic and orthotopic sites.

Estimates of dose to intraperitoneal micrometastases from alpha and beta emitters in radioimmunotherapy

Intraperitoneal metastases from ovarian and other gynecologic tumors are a significant source of treatment failure. In recent years, investigators have used radiolabeled monoclonal antibodies to treat this disease with encouraging results. We have developed a dose calculational technique which generates isodose distributions from intraperitoneally administered alpha and beta particle emitters. In this study we apply the calculations to tissue biopsy samples to determine the adequacy of dose to ovarian micrometastases. Tissue samples from staging biopsies at the time of surgical debulking are scanned to identify small metastases. The patient population studied comprised those with ovarian disease who based on clinical criteria would be considered good candidates for intraperitoneal radioimmunotherapy. The regions of interest (which include the tumor and surface of the peritoneum) are digitized and tumor volumes are contoured. Dose calculations based on the modeling of intraperitoneally administered antibodies radiolabeled with various isotopes is performed and the minimum dose to tumor and normal tissue is assessed. For example, with tumor uptake of 0.1% injected dose per gram of tissue, the surface tumor dose from alpha emitters is up to 45,000 rads. The dose falls to 6000 rads at approximately 40 microns from the peritoneal surface. The surface dose from 20 mCi 90Y administered in 1500 ml saline is up to 10,000 rads, and at a 2-mm depth, approximately 2000 rads. From our calculation dose distribution from radioimmunotherapy varies as a function of physical characteristics of the isotope, absorption of activity, and amount of disease being treated.

In vitro investigations on induction and reversal of cisplatin resistance in a rat ovarian tumor cell line

Resistance of a rat ovarian tumor cell line (O-342/DDP) to cisplatin was induced in vitro by stepwise increase of cisplatin concentrations. Both chemosensitive parental cells (O-342) and resistant O-342/DDP cells grow in a monolayer and enter log-phase growth about 24 h after seeding (cell population doubling time in log-phase growth is about 24 h). O-342/DDP cells show a 33-fold resistance to cisplatin as compared to O-342 cells (ID50 = 33 microM in O-342/DDP vs 1 microM in O-342 cells). The intracellular total glutathione (GSH + GSSG) of O-342/DDP cells was twice as high as that of O-342 cells (3.04 vs 1.37 nmol/10(6) cells), while the intracellular GSSG was increased by 26% in O-342/DDP cells compared to O-342 cells. DNA interstrand crosslinks were found to be 8.5 times higher in O-342 cells than in O-342/DDP cells (204 vs 24 rad equiv.), following cisplatin treatment. DNA single-strand breaks were approximately doubled in the sensitive line as compared to the resistant line following exposure to cisplatin. Chromosome analysis uncovered a change in the karyotype of O-342/DDP cell as compared to O-342 cells. In the sensitive line hyperploid (3n) clones, in the resistant line near-diploid clones predominated. Both DL-buthionine-(S,R)-sulfoximine and 3-aminobenzamide were able to sensitize the resistant line towards cisplatin. Thus, the present results suggest that mechanisms for cisplatin resistance in this tumor line apparently are multi-factorial, and include a higher intracellular GSH content and an increased repair activity.

[Chemical evaluation of vinegar-processing method for fresh rhizoma Corydalis]

Qualitative and quantitative analysis were carried out on the samples of Rhizoma Corydalis in both the locally vinegar-processed (fresh) and traditionally vinegar-processed forms. No difference was found in the main chemical constituents. However, both the total alkaloids and the corydalis B content of the former are higher than those of the latter.

[A new serotype of Shigella boydii]

Two strains which belong to the same serotype of Shigella were isolated from the bloody-pus stool of two patients (in 1986) and is reported in this paper. The results were identical both showing agglutination in low titer with serotype 8 of S. dysenteriae and serotype 4 of S. boydii when the two strains were checked well with all kinds of diagnostic antisera and vice versa, ie the antisera produced by the two strains were also checked well with sera prepared with the representative strains of all Shigella spp. No cross agglutination with O6, O7, and O150 of E. coli were found. Consequently, It appears to be a new serotype of Shigella. These two strains possess the ability of causing keratitis in guinea-pigs as well as invading epithelial cells, the DNA of both strains in agarose-electrophoresis showed a large plasmid, indicating that they are virulent strains possessing invasive ability. It was concluded that these two strains belonged to Shigella boydii as they fermented mannitol and non-related antigenically with Shigella flexneri. Since serotype 1-18 of S. boydii have been reported recently, we propose that this new serotype should be serotype 19 of Shigella boydii.

Cooperation between bovine leukaemia virus transactivator protein and Ha-ras oncogene product in cellular transformation

Human T-lymphotropic viruses (HTLV-I and -II) and bovine leukaemia virus (BLV) express transactivator proteins able to increase long terminal repeat (LTR) directed viral expression. These transacting factors are though to be involved in the induction of leukaemia by these viruses. Transfection of BLV transactivator p34tax together with Ha-ras immortalizes and transforms rat embryo fibroblasts, in vitro. The transformed cell induce tumours in nude mice. These data emphasize the causal role exerted by p34tax in in vivo tumorigenesis.

Enhancement of cisplatin (DDP) antitumor activity by 3-aminobenzamide in rat ovarian tumors sensitive and resistant to DDP in vivo

A cisplatin (DDP)-resistant rat ovarian tumor cell line (O-342/DDP) and its parental sensitive counterpart (O-342) were used to investigate the combination effect of DDP plus 3-aminobenzamide (3-AB), an inhibitor of adenosine diphosphate ribose transferase (ADPRT). Treatment with six doses of DDP in NMRI nude mice bearing O-342/DDP produced an increase in mean survival of only 1 day over that of controls (P less than 0.05). The addition of nontoxic doses of 3-AB (5 mM/kg x 6) increased the mean survival to 6.4 days compared with that obtained with DDP treatment alone (P less than 0.001). In the sensitive ovarian tumor line (O-342), the combination effect of DDP plus 3-AB was even more impressive: simultaneous treatment of NMRI nude mice bearing O-342 with three doses of DDP plus 3-AB increased the mean survival by 2 weeks and the median survival by 3 weeks over that achieved with DDP treatment alone. Possible mechanisms involved in the potentiation of DDP activity and the possible clinical potential of this combination are discussed.

HPLC procedure for the pharmacokinetic study of the spin-trapping agent, alpha-phenyl-N-tert-butyl nitrone (PBN)

Considerable progress has been made in the use of spin-trapping agents for the trapping of free radicals in biological systems. Radicals have been detected in both in vitro and in vivo systems using this methodology. Free radicals have not only been identified by this procedure, but also the intensity of radical generation and the duration of their production has been assessed as well. One of the most widely used spin-trapping agents in biological systems is PBN. This spin trap appears to be relatively nontoxic at the levels required for successful trapping experiments, but there is no information concerning the possible fate of PBN in such biological systems. Metabolism of PBN could alter the concentration of PBN at the site of trapping which may affect the efficiency of radical capture, especially in in vivo systems. In this study, PBN was administered intraperitoneally to rats and the concentration of the spin trap in various organs was determined by high pressure liquid chromatography as a function of time (15 min to 12 h). The concentration of PBN in plasma peaked at 15 min while the maximum in all organs tested occurred at 30 min. The time course of PBN concentrations in all tissues followed similar curves, and declined rather steeply after the 30-min maximum with a biological half-life of 134 min. However, the amount of PBN per gram of tissue was always higher in liver and kidney than in the brain, heart, and lung. PBN was detected in the urine for as long as 24 h after injection of the compound.

Effects of cigarette smoking on hemodynamics and hypoxic pulmonary vasoconstriction: role of prostaglandins and leukotrienes

This study investigated the role of prostaglandins (PGs) and leukotrieres (LTs) in hypoxic pulmonary vasoconstriction (HPV) and in cigarette smoking-induced changes in hemodynamics and HPV in Wistar rats. Selective LTD4-LTE4 receptor antagonist LY-171883 (LY) inhibited HPV by 71.8%, while cyclooxygenase inhibitor indomethacin (IND) augmented HPV. The results indicate that LTs mediate HPV in Wistar rats. Smoking increased the level of TXB2 over control by 143.6% in plasma and 69.2% in lung tissue, concomitantly, pulmonary and systemic vascular resistance (PVR and SVR) were increased by 38.7% and 46.7%, respectively. Both LY and IND prevented the smoking-induced increase of PVR and SVR. After smoking HPV increased twofold. The increase of HPV was abolished by LY, but not by IND. Our results suggest that smoking leads to pulmonary and systemic vasoconstriction partly mediated by TXA2 and LTs; smoking also leads to an augmentation of HPV, and LTs play an important role in it.

Synthesis of functional bovine leukemia virus (BLV) p34tax protein by recombinant baculoviruses

The bovine leukemia virus (BLV) p34tax (also called tat, p34, XLOR gene product) is a 34-kDa polypeptide encoded in the 3'-terminal region of the virus. This protein is responsible for positive transcriptional trans-activation of promoter elements located within the BLV long-terminal repeat. We introduced the protein-coding region of BLV p34tax into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus. After infection of the insect Spodoptera frugiperda (SF9) cell line, this recombinant strain of baculovirus produced approximately 100 to 150 mg of p34tax per 2 X 10(9) cells. This protein, when introduced into mammalian fibroblasts by using a cell-to-cell fusion technique, functionally trans-activated the BLV long-terminal repeat. Analysis of 32P-labeled proteins of SF9 cells expressing BLV tax by two-dimensional gel electrophoresis indicated that the BLV p34tax was phosphorylated.

Endothelium-dependent relaxation and hyperpolarization of canine coronary artery smooth muscles in relation to the electrogenic Na-K pump

1 In the smooth muscle cells of canine coronary artery, acetylcholine (ACh) produced a transient, endothelium-dependent hyperpolarization of the membrane. A similar hyperpolarization was also elicited by exposure to Krebs solution after incubation of the artery in K-free solution for 30 min. 2 A hyperpolarization of reproducible amplitude was generated when ACh was applied at intervals greater than 30 min. Repetitive application of ACh at 15 min intervals caused a successive reduction in the amplitude of hyperpolarization. 3 The reduction in the amplitude of relaxation during five successive applications of ACh at 15 min intervals was less than 10% of the first relaxation. 4 The ACh-induced hyperpolarization was blocked by atropine but not by ouabain, whereas the K-free induced hyperpolarization was blocked by ouabain. In low Na (Li-substituted) solution, ACh still induced a hyperpolarization but the K-free induced hyperpolarization was absent. 5 In coronary artery precontracted by high-K solution, ACh produced an endothelium-dependent relaxation, without membrane hyperpolarization. The associated relaxation was resistant to ouabain but sensitive to atropine. 6 It is concluded that in the canine coronary artery, the electrogenic Na-K pump does not contribute to the endothelium-dependent hyperpolarization or relaxation. The results are consistent with the release of two different inhibitory factors from the vascular endothelium.

Studies on peripheral T lymphocyte subsets in patients with autoimmune thyroid diseases

Peripheral T lymphocyte subsets in 60 cases of Graves' disease (GD) and 16 cases of Hashimoto's thyroiditis (HT) were determined by the use of OKT monoclonal antibodies (McAb). The results showed that in both diseases OKT3 cells (total T cells) and OKT8 cells (suppressor T cells, TS cells) were lower and the ratio of OKT4 cells (helper T cells, TH cells) OKT8 cells was much higher than those in normal controls. GD patients who were treated with antithyroid drugs (ATD) and whose serum T3, T4 recovered to normal, could be further divided into subgroups of high OKT4/OKT8 cell ratio and of normal ratio. The pathogenesis, treatment and relapse of autoimmune thyroid diseases (AITD) were discussed in this paper on the basis of the results.

[Influence of total parenteral nutrition on amikacin pharmacokinetics]

Six patients under total parenteral nutrition (TPN) and eight control patients received 200 mg of amikacin by iv infusion in 0.5 h. Amikacin concentrations of serum and urine were determined by fluorescence polarization immunoassay. At 6 h after the beginning of administration, the amikacin level in serum of TPN group (2.3 +/- 0.8 micrograms/ml) was significantly higher than control (1.3 +/- 0.8 microgram/ml). There was no significant difference between the 24-h urine output of 2 groups. Pharmacokinetic calculations were based on a two-compartment open-system model. The T1/2 beta and apparent volumes of distribution (Vc, Vdss, V2) of TPN group were significantly greater than those of control group. The body clearance of amikacin in TPN group was slower than control. It is suggested that serum amikacin concentrations should be monitored in clinical TPN patients to prevent toxic reactions.

Determination of intracellular reduced glutathione and glutathione related enzyme activities in cisplatin-sensitive and resistant experimental ovarian carcinoma cell lines

The level of GSH in ovarian carcinoma cells which were sensitive and resistant to cisplatin was serially determined following tumor removal from the animals, in addition, activities of GSH-reductase and GSH-S-transferase were assessed. The GSH level in the resistant line (O-342/DDP) was almost twice as high as that in its sensitive counterpart (O-342), when determined immediately following removal of the tumor (1.55 +/- 0.47 vs. 0.81 +/- 0.32 nmol/10(6) cells). Culturing the cells resulted in a decrease of GSH levels in both cell lines during the first 4 h. Thereafter, GSH levels in both cell lines increased up to 24 h. At this time the GSH level was higher in O-342 than in O-342/DDP. GSH-reductase activity in O-342/DDP cells was significantly higher than in O-342 cells when the enzyme was determined immediately after tumor removal; at the same time there was no difference in activity of GSH-S-transferase between two cell lines. After 24 h in culture, no significant difference between O-342 and O-342/DDP cells could be observed in the activity of the two enzymes.

Structural and functional characterization of mutants of the bovine leukemia virus transactivator protein p34

Mutants of the bovine leukemia virus (BLV) transactivator protein (tat, tax, p34, the XLOR gene product) were constructed by site-directed deletions, in-phase linker insertions, or fragment replacements (swapping) among BLV variants. The mutant constructs were transfected into cos cells and transiently expressed. Western blot analysis using a mixture of monoclonal antibodies to wild-type p34 revealed the presence of mutated XLOR gene products in all the mutants tested. The transactivating activity of 11 tax mutants containing site-directed deletions and in-phase linker insertions was completely abolished. Only the swapping mutant tested, a hybrid between two BLV variants, transactivated LTR-directed gene expression at wild-type levels. These data illustrate the narrow range of structural variations that allow full activity of the BLV tax product and suggest that the present molecular structure of the transactivator protein results from heavy evolutionary constraints.

Subclasses of antibodies to hepatitis B core antigen in chronic HBV infection: changes during treatment with alpha interferons and predictors of response

Response to interferon therapy in chronic hepatitis B virus (HBV) carriers is preceded by the appearance of IgM class anti-HBc (antibody to hepatitis B core antigen). The temporal relationship and magnitude of the IgM anti-HBc response is variable suggesting that the antibody is not directly involved in hepatocyte lysis, but is merely a marker of a changed state of immunity to the nucleocapsid proteins, induced by interferon. IgG 1, 2, 3, and 4 class anti-HBc did not change during therapy, but IgG 3 anti-HBc was significantly lower in responders than non-responders. IgG anti-HBc of all subclasses was absent in two Chinese HBV carriers. Lower than normal titres of anti-HBc (p less than 0.001) were detected in human immunodeficiency virus antibody positive (anti-HIV) HBV carriers. These data indicate the presence of altered immunity to the nucleocapsid antigens in these two types of chronic HBV carrier that are known to respond poorly to antiviral therapy.

Biological activity of hydroxylated chloroethylnitrosoureas

1-Nitroso-1-(2-hydroxyethyl)-3-(2-chloroethyl)urea (Compound I) and 1-nitroso-1-(2-hydroxypropyl)-3-(2-chloroethyl)urea (Compound II) display significantly reduced antitumor activity compared to the corresponding isomeric derivatives 1-nitroso-1-(2-chloroethyl)-3-(2-hydroxyethyl) urea (Compound III) and 1-nitroso-1-(2-chloroethyl)-3-(2-hydroxypropyl) urea (Compound IV). Their low therapeutic activity is paralleled by low toxicity while mutagenicity and carcinogenicity are high. A comparative investigation of the genotoxicity of Compounds I and III using primary cultures of fetal hamster lung cells revealed an about 14-fold higher rate of DNA single-strand breaks following exposure (100 microM, 1 h) to Compound I as compared to Compound III. The rate of DNA interstrand cross-links, on the other hand, was 11-fold higher following Compound III as compared to Compound I. The results underline that the therapeutic activity of chloroethylnitrosoureas is mainly attributable to their cross-linking potential while induction of DNA single-strand breaks plays a decisive role for mutagenicity and carcinogenicity but appears not to be relevant for antineoplastic effectiveness.

Long-term effects of progestin and RU 486 on prolactin production and synthesis in human endometrial stromal cells

Previous studies have shown that the production of prolactin (PRL) is increased in human endometrial stromal cells cultured with medroxyprogesterone acetate (MPA) for 3-5 days. In the present study, we have investigated the effect of prolonged treatment of progestin and anti-progestin, RU 486, on the production and synthesis of PRL. Stromal cells were isolated from human endometrium obtained from non-pregnant women and cultured for 20-30 days in medium RPMI 1640 with 2% fetal calf serum or supplemented with MPA, RU 486, alone or in sequence. The PRL content in medium was measured by radioimmunoassay. The production rate was estimated from the PRL content in medium accumulated in 24 h. The PRL production rate was progressively increased in stromal cells continuously treated with MPA for 30 days (greater than 100-fold over the control value, i.e. 0-0.01 microgram/0.1 mg cell DNA/day). RU 486 alone had no effect on the production of PRL. However, the production of PRL was increased by MPA in stromal cells pretreated with RU 486 indicating that the effect of RU 486 is reversible. When stromal cells were treated with MPA and RU 486 sequentially, RU 486 stimulated the PRL production (approximately 2-fold over the MPA-treated cells) for 2-3 days and then reduced to basal levels over a 5-day period. The stimulatory and inhibitory effects of RU 486 on PRL production in stromal cells pretreated with progestin was also observed in the rate of synthesis of PRL estimated by incubating the stromal cells with [35S]methionine and immuno-isolating the [35S]PRL with anti-PRL.(ABSTRACT TRUNCATED AT 250 WORDS)

More monensin-sensitive, ammonia-producing bacteria from the rumen

Two monensin-sensitive bacteria which utilized carbohydrates poorly and grew rapidly on amino acids were isolated from the bovine rumen. The short rods (strain SR) fermented arginine, serine, lysine, glutamine, and threonine rapidly (greater than 158 nmol/mg of protein per h) and grew faster on casein digest containing short peptides than on free amino acids ().34 versus 0.29 h(-1)). Gelatin hydrolysate, an amino acid source containing an abundance of long peptides, was unable to support growth or ammonia production, but there was a large increase in ammonia production if strain SR was cocultured with peptidase-producing ruminal bacteria (Bacteroides ruminicola or Streptococcus bovis). Cocultures showed no synergism with short peptides. Strain SR washed out of continuous culture ().1 h(-1)) at pH 5.9. The irregularly shaped organisms (strain F) deaminated glutamine, histidine, glutamate, and serine rapidly (greater than 137 nmol/mg of protein per min) and grew faster on free amino acids than on short peptides ().43 versus 0.21 h(-1)). When strain F was provided with casein or gelatin hydrolysate and cocultured with peptidase-producing bacteria, there was a more than additive increase in ammonia production. Strain F grew in continuous culture (0.1 h(-1)) when the pH was as low as 5.3. The irregularly shaped cells and short rods were present at less than 10(9)/ml in vivo, but they ahd very high specific activities of ammonia production (greater than 310 nmol of ammonia/mg of protein per min) and could play an important role in ruminal amino acid fermentation.

Some electrical properties of the endothelium-dependent hyperpolarization recorded from rat arterial smooth muscle cells

1. Electrical responses produced by acetylcholine (ACh) and histamine were recorded from smooth muscle cells of the intralobular small pulmonary artery (SPA), main pulmonary artery (MPA) and thoracic aorta of rats. 2. In MPA and SPA, ACh and histamine produced a transient hyperpolarization of the membrane, and the potential decayed exponentially with a time constant of 2-3 min. In aorta, ACh produced a sustained and histamine produced a transient hyperpolarization. 3. The ACh- and histamine-induced hyperpolarizations were blocked by atropine and mepyramine, respectively, or by removing the endothelial cells. 4. The amplitude of the hyperpolarization was increased in low [K+]o solutions and decreased in high [K+]o solutions. The ionic conductance of the membrane was increased during the hyperpolarization, suggesting an involvement of the increased potassium conductance. 5. A reproducible amplitude of hyperpolarization was generated when ACh or histamine was applied at intervals of over 10 or 30 min, respectively. 6. In aorta, after the transient hyperpolarization had ceased during continued application of histamine, ACh again produced a hyperpolarization, i.e. the transient nature of the hyperpolarization was not due to desensitization of the receptor upon which the hyperpolarizing substance acted, assuming histamine and ACh release the same hyperpolarizing substance. 7. ACh and histamine relaxed the tissues from SPA, MPA and aorta during the noradrenaline (NA)- or high [K+]o solution-induced contraction, in a concentration-dependent manner, only when the endothelial cells were intact. Both ACh and histamine were potent relaxants in MPA and aorta, but showed weak relaxing actions in SPA. 8. In aorta, ACh and histamine produced a sustained relaxation for up to 10 min, and Methylene Blue diminished and altered it to a transient relaxation (for histamine) or an initial large, followed by a small sustained (for ACh), relaxation. 9. In the presence of NA and NA plus Methylene Blue, ACh and histamine also produced a hyperpolarization similar to that seen in the control. 10. It is concluded that in arteries of the rat, ACh and histamine release a hyperpolarizing substance from the endothelial cells. This substance may be different from the endothelium-derived relaxing factor (EDRF), and is released mainly transiently. The hyperpolarization is generated by an increase in potassium conductance of the membrane, and this has some contribution to the endothelium-dependent relaxation.

Impedance cardiography-dipyridamole test in detecting coronary artery disease

Thallium-201 dipyridamole test (Tl-201DT) has high sensitivity and specificity in the assessment of coronary disease (CAD), but is not always available. We proposed impedance cardiography DT (IDT)instead. To determine the characteristic changes of impedance cardiogram (ICG) in patients with typical angina and to compare with those in normal subjects, 37 subjects undergoing IDT were divided into 3 groups: typical angina (15), suspected chest pain (11) and normals (11). Dipyridamole (DP) was infused intravenously for over 10 minutes at a total dose of 0.75 mg/kg. Simultaneous recording of ECG, PCG, and ICG were repeated immediately 2 minutes and 4 minutes after infusion of DP, and immediately and 5 minutes after intravenous infusion of aminophylline. Eleven parameters, HR, SPRP, QZ/ZA2, HI, SV, CO, A wave, A/C, O wave, O/C, A + O/C were observed. Only in O/C and A + O/C there were changes of significant differences (P less than 0.01) between groups. Specificity was 100% (0/11 positive) in normals. Sensitivity was 80% (12/15 positive) in the angina group, but only 46.7% (7/15) with ECG. The characteristic changes in CAD patients during IDT were angina induced by DP, abnormal O wave on ICG and change from deep A wave to abnormal O wave. No serious complication occurred after IDT. Our results indicate that IDT is a simple, practical and valuable method for detecting CAD.

Acetylcholine releases endothelium-derived hyperpolarizing factor and EDRF from rat blood vessels

1. The effects of haemoglobin and methylene blue on the acetylcholine (ACh)-induced electrical and mechanical responses of smooth muscle cells were investigated in rat aorta and rat main pulmonary artery. 2. When the endothelium was intact, ACh induced a transient hyperpolarization and sustained relaxation of tissues precontracted with noradrenaline. Both hyperpolarization and relaxation were absent in preparations without endothelium. 3. Haemoglobin and methylene blue inhibited the ACh-induced relaxation, but not the transient hyperpolarization. 4. In aorta with an intact endothelium, ACh produced an increase in both the rate of 86Rb efflux and tissue cyclic GMP levels. The changes in ion flux were unaffected by either haemoglobin or methylene blue in concentrations which almost abolished the increase in cyclic GMP concentrations. 5. In arteries with an intact endothelium, indomethacin had no effect on the ACh-induced electrical and mechanical responses or on the increase in 86Rb efflux and tissue cyclic GMP levels. 6. It is concluded that in the rat aorta and rat main pulmonary artery, ACh releases two different substances, an endothelium-derived relaxing factor (EDRF) and a hyperpolarizing factor (EDHF), from the endothelial cells. Neither substance appears to be derived from a pathway dependent on cyclo-oxygenase. EDHF seems to play a minor role in the relaxation of noradrenaline-induced contractions.

Even transcriptionally competent proviruses are silent in bovine leukemia virus-induced sheep tumor cells

To investigate the role of proviral integration and expression in cellular transformation induced by bovine leukemia virus (BLV), three BLV-induced tumors harboring a single proviral copy were selected upon restriction and hybridization analysis. Tumors 344 and 395 were shown to contain a full-size proviral copy, whereas in tumor 1345 the provirus appeared to be heavily deleted. RNA gel blot hybridization with an antisense RNA probe showed no transcription of the viral sequences in the fresh tumors or in sheep tumor cells growing in vitro. The proviruses were cloned and transfected in mammalian cell lines. Transient-expression experiments revealed that the complete proviruses were still able to express the trans-activating protein (Tat) as well as structural proteins, demonstrating that the nonexpression of a provirus in a tumor cell does not necessarily imply a structural alteration of the viral information. In contrast, sequence analysis of the provirus with a large deletion and transient-expression assays proved that this truncated provirus, isolated from a tumor, was unable to code for viral proteins. These data indicate that expression of viral genes, including tat, is not required for the maintenance of the transformed state.

The Magnon Pairing Mechanism of Superconductivity in Cuprate Ceramics

The magnon pairing mechanism is derived to explain the high-temperature superconductivity of both the La2-xSrxCu(1)O(4) and Y(1)Ba(2)Cu(3)O(7) systems. Critical features include (i) a one- or two-dimensional lattice of linear Cu-O-Cu bonds that contribute to large antiferromagnetic (superexchange) coupling of the Cu(II)(d(9)) orbitals; (ii) holes in the oxygen ppi bands [rather than Cu(III)(d(8))] leading to high mobility hole conduction; and (iii) strong ferromagnetic coupling between oxygen ppi holes and adjacent Cu(II)(d(9)) electrons. The ferromagnetic coupling of the conduction electrons with copper d spins induces the attractive interaction responsible for the superconductivity, leading to triplet-coupled pairs called "tripgems." The disordered Heisenberg lattice of antiferromagnetically coupled copper d spins serves a role analogous to the phonons in a conventional system. This leads to a maximum transition temperature of about 200 K. For La(1.85)Sr(0.15)Cu(1)O(4), the energy gap is in excellent agreement with experiment. For Y(1)Ba(2)Cu(3)O(7), we find that both the CuO sheets and the CuO chains can contribute to the supercurrent.

Expression in bacteria of beta-galactosidase fusion proteins carrying antigenic determinants of the two X gene products of bovine leukemia virus

A cDNA corresponding to the bovine leukemia virus post-envelope region (X gene) was subcloned into the lambda gt11 expression vector. Two large protein fragments corresponding respectively to the long and short open reading frames of the X region were expressed as beta-galactosidase fusion proteins. These products were specifically recognized by sera from bovine leukemia virus-infected cattle.

The bovine leukemia virus p34 is a transactivator protein

Recombinant Moloney murine retroviruses containing the BLV post-envelope long open reading frame were constructed and transfected into the psi 2 packaging cell line. They were shown to encode and to express a 34-kd protein able to transactivate the BLV long terminal repeat-directed gene expression in the respective transfected cells. These data demonstrate that the BLV X-LOR gene encodes a p34 transactivator product. Furthermore, the different cell lines produced infectious recombinant retroviruses capable of transferring X-LOR genes into recipient cells. The availability of the BLV transactivator protein should allow us to understand the role of the transactivator protein in BLV-induced leukemogenesis.

Effect of hydrophobicity of utilization of peptides by ruminal bacteria in vitro

When mixed ruminal bacteria were incubated with a pancreatic casein hydrolysate and free amino acids of a similar composition, rates of ammonia production were much greater for peptides than for amino acids. The pancreatic digest of casein was then fractionated with 90% isopropyl alcohol. Hydrophobic peptides which dissolved in alcohol contained an abundance of phenolic and aliphatic amino acids, while the hydrophilic peptides which were precipitated by alcohol contained a large proportion of the highly charged amino acids. The Km values of the mixed ruminal bacteria for each fraction were similar (0.88 versus 0.98 g/liter), but the Vmax of the hydrophilic peptides was more than twice that of the hydrophobic peptides (18 versus 39 mg of NH3 per g of bacterial protein per h). Pure cultures of ruminal bacteria had a similar preference for hydrophilic peptides and likewise utilized peptides at a faster rate than free amino acids. Since peptide degradation rates differed greatly, hydrophobicity is likely to influence the composition of amino acids passing unfermented to the lower gut of ruminant animals.

A procedure for measuring peptides in rumen fluid and evidence that peptide uptake can be a rate-limiting step in ruminal protein degradation

A relatively simple and sensitive procedure was developed to measure the concentration of peptides in rumen fluid. Feed particles and microorganisms were removed by centrifugation, and the supernatant was treated with perchloric acid (5% final concentration). Perchloric acid precipitated macromolecules that included protein, RNA, and DNA. Perchlorate was subsequently removed by precipitation with an excess of potassium carbonate. Ammonia was removed by boiling the alkaline sample. Supernatant samples were then analyzed for ninhydrin reactive material before and after HCl hydrolysis. Because ninhydrin reaction was 3 to 7.5 times greater after HCl hydrolysis, peptides rather than amino acids were the primary source of nonprotein, nonammonia nitrogen. Rumen fluid from a cow fed timothy hay and concentrate supplement (16% crude protein) contained more than 1200 mg peptides/L (192 mg N/L), 1 h after feeding, and this value declined the prefeeding value of 400 mg/L (64 mg N/L) by 8 h after feeding. Comparison of ninhydrin reactivity with and without HCl hydrolysis indicated that peptides present before feeding contained more peptide bonds than the peptides soon after feeding. High pressure liquid chromatography revealed a variety of peaks soon after feeding and fewer dominant peaks 8 h later. The data suggest that peptide uptake into rumen microorganisms can be a rate-limiting step in ruminal protein degradation.

Concentration and estimated flow of peptides from the rumen of dairy cattle: effects of protein quantity, protein solubility, and feeding frequency

Experiments were conducted to ascertain the effect of dietary protein (type and amount) and feeding frequency on peptide concentration and flow from the rumen of lactating Holstein cows. When rations supplemented with soybean meal were fed 12 times/d and CP was 14.5, 17.1, or 20.6%, the estimated flow of N from the rumen was 22, 33, and 34 g/d, respectively. When the soybean meal was autoclaved to decrease protein solubility (14.4, 16.9, and 19.3% CP the flow of peptide N was 19, 26, and 31 g/d, respectively. In both of these experiments rumen volume and dilution rate remained relatively constant throughout the day, and flow was proportional to concentration. If the cows were fed rations containing 17.8% CP once a day, the peptide concentration and dilution rate were highest 2 h after feeding and declined significantly thereafter. Replacement of half the soybean protein with either extruded soybean meal or fish meal decreased the flow of peptide N from the rumen (19 versus 14 and 15 g/d, respectively). Because the total flow of soluble protein and ammonia as well as peptides was less if cows were fed once a day than 12 times per day, increased feeding frequency appeared to increase ruminal proteolysis.

Simultaneous visualization of vascular permeability change and leukocyte egress in the central nervous system during autoimmune encephalomyelitis

An unresolved issue in the study of demyelinating disease is whether blood-brain barrier damage is dependent upon the migration of inflammatory cells into the central nervous system (CNS). In a study of experimental autoimmune encephalomyelitis (EAE) in rabbits, a freeze-dried, paraffin-embedded tissue technique was exploited to enable (1) the immobilization of intravenously injected sodium fluorescein tracer, as an index of vascular permeability; and (2) an effective labeling by monoclonal antibodies of both T-lymphocytes and mononuclear phagocytes in "unfixed" neural tissue. Using these newly combined methods, evidence was found that increased vascular permeability in the CNS during EAE occurs concomitantly with, and not prior to, infiltration by mononuclear phagocytes.

Radiographic and histologic analyses of stress fracture in rabbit tibias

Sequential changes in remodeling of the internal structure of the tibia caused by controlled, excessive jumping and running were studied in 20 rabbits. Vascular changes and circulatory disturbances within the cortical bone occurred before osteoclastic resorption. Degeneration and necrosis of osteocytes due to circulatory disturbances also occurred. Periosteal new bone formation, found at and after 12 days of the experiment, was a compensatory reaction to support the tibia weakened by accelerated osteoclastic resorption. Small cracks appeared at the cement line and developed through the neighboring cement line of the haversian systems. At 21 days, incomplete fracture of the tibial cortex was found in two rabbits. Complete fracture through one side of the cortex was seen in one animal at the 50th day of the experiment. In this study, however, most of the tibias did not have visible fracture lines after a period of stressful exercise. This result suggests that most tibias adapt to changes in stress requirements through proper internal remodeling so that a complete fracture does not occur.