Intermittent treatment of prostaglandin E2 with risedronate is more anabolic than prostaglandin E2 alone in the proximal tibial metaphysis of ovariectomized rats

This study is designed to test how intermittent application of prostaglandin E2 (PGE2) and risedronate (Ris) alone or in combination acts on the cancellous bone mass in estrogen-deficient rats. Sprague-Dawley rats were ovariectomized (ovx) or sham-ovx'd at 6 months of age. PGE2 (6mg/kg/d), Ris (5 micrograms/kg/twice a week) or PGE2 plus Ris were given for 60 days to ovx rats immediately after operation and followed by 60 days without treatment. The drugs were then reapplied for another 60 days. Static histomorphometry was performed on the secondary spongiosa of proximal tibial metaphysis (PTM). Sixty days of ovx lost trabecular bone and number, Ris prevented ovx-induced bone loss. PGE2 added 48% extra cancellous bone, but the new bone was completely lost after 60 days of withdrawal. Another 60 days of PGE2 treatment only partially restored the trabecular bone, the bone mass was still -42% lower than that of sham-ovx controls. Co-treatment of PGE2 with Ris added the same amount of bone as PGE2 alone after the first 60 days treatment period, but differed from PGE2 alone in that the new bone lost less during the 60 days withdrawal period. Re-application of co-treatment for another 60 days added more extra bone. We concluded that intermittent co-treatment with anabolic and anti-resorptive agents is more effective than anabolic agent alone in long-term therapy of cancellous bone in estrogen-deficient rats.

Platelet-activating factor induces NF-kappa B activation through a G protein-coupled pathway

The capability of platelet-activating factor (PAF) to induce transcription factor activation was examined. In stably transfected Chinese hamster ovary cells expressing the PAF receptor (CHO-PAFR), PAF stimulation resulted in the nuclear expression of a DNA binding activity with specificity to the kappa B sequence. The p50 and p65 proteins, constituents of the prototypic nuclear factor kappa B (NF-kappa B), were identified as components of the DNA protein complexes by antipeptide antibodies in gel supershift as well as UV cross-linking experiments. PAF induced an initial decrease and subsequent increase of cytoplasmic I kappa B alpha levels, accompanied by up-regulation of the I kappa B alpha messenger RNA, a feature of NF-kappa B activation. PAF-induced kappa B binding activity was detected within 15 min after agonist stimulation, peaked at 30-40 min, and remained detectable by 2.5 h. SR 27417, a PAF receptor antagonist, blocked PAF-induced kappa B binding activity but not that induced by tumor necrosis factor-alpha (TNF alpha). Cholera toxin treatment markedly reduced PAF-induced kappa B binding activity, whereas pertussis toxin had no significant inhibitory effect. Neither of the two toxins affected the kappa B binding activity induced by TNF alpha in the same cells. In addition to the CHO-PAFR cells, PAF stimulated kappa B binding activity in the murine P388D1 macrophage and the human ASK.0 B cell lines that express endogenous PAF receptors. These results imply a potential role of PAF in the regulation of gene expression through a G protein-coupled transcription factor activation pathway.

The major protein of guayule rubber particles is a cytochrome P450. Characterization based on cDNA cloning and spectroscopic analysis of the solubilized enzyme and its reaction products

Guayule plants accumulate large quantities of rubber within parenchyma cells of their stembark tissues. This rubber is packed within discrete organelles called rubber particles composed primarily of a lipophilic, cis-polyisoprene core, small amounts of lipids, and several proteins, the most abundant of which is the M(r) 53,000 rubber particle protein (RPP). We have cloned and sequenced a full-length cDNA for RPP and show that it has 65% amino acid identity and 85% similarity to a cytochrome P450 known as allene oxide synthase (AOS), recently identified from flaxseed. RPP contains the same unusual heme-binding region and possesses a similar defective I-helix region as AOS, suggesting an equivalent biochemical function. Spectral analysis of solubilized RPP verifies it as a P450, and enzymatic assays reveal that it also metabolizes 13(S)-hydroperoxy-(9Z,11E)-octadecadienoic acid into the expected ketol fatty acids at rates comparable with flaxseed AOS. RPP is unusual in that it lacks the amino-terminal membrane anchor and the established organelle targeting sequences found on other conventional P450s. Together, these factors place RPP in the CYP74 family of P450s and establish it as the first P450 localized in rubber particles and the first eukaryotic P450 to be identified outside endoplasmic reticulum, mitochondria, or plastids.

Platelet-activating factor stimulates transcription of the heparin-binding epidermal growth factor-like growth factor in monocytes. Correlation with an increased kappa B binding activity

Human peripheral blood monocytes responded to stimulation of platelet-activating factor (PAF) with up-regulation of the transcript for heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent mitogen for vascular smooth muscle cells. This function of PAF was observed at nanomolar concentrations of the ligand, starting at 30 min after stimulation. The PAF-induced up-regulation of HB-EGF mRNA was accompanied by an increase in kappa B binding activity. These functions of PAF appeared to be mediated through the cell surface PAF receptors, as two PAF receptor antagonists, WEB 2086 and L-659,989, blocked both the up-regulation of HB-EGF mRNA and kappa B binding activity induced by PAF. The antagonists, however, had no effect on phorbol ester-induced up-regulation of HB-EGF mRNA and kappa B binding activity. Pretreatment of monocytes with pertussis toxin inhibited these functions of PAF, whereas cholera toxin had no inhibitory effect. Pyrrolidine dithiocarbamate, an inhibitor for NF-kappa B activation, markedly reduced PAF-stimulated kappa B binding activity as well as up-regulation of HB-EGF mRNA. These results suggest a potential role of PAF in HB-EGF expression and provide evidence that this stimulation may occur through increased kappa B binding activity.

Immunization with vesicular stomatitis virus nucleocapsid protein induces autoantibodies to the 60 kD Ro ribonucleoprotein particle

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disorder of unknown etiology that is characterized by antibodies binding ribonucleoprotein complexes. The epitopes of SLE associated 60 kd Ro (or SSA) autoantigen share sequence with vesicular stomatitis virus (VSV) nucleocapsid (N) protein and SLE patients with anti-Ro are more likely to bind the N-protein than anti-Ro negative patients.

METHOD

We immunized New Zealand white (NZW) rabbits with purified VSV N-protein to examine the relationship between the immune response to N-protein and anti-Ro.

RESULTS

After multiple immunizations with VSV N-protein, NZW rabbits produced not only IgG antibodies to VSV N-protein but also an autoimmune response to Ro antigen. The IgG fraction of the rabbit immune serum precipitates 60 kd Ro protein as well as its associated Y RNAs. Antibodies elicited by 10 immunizations of VSV N-protein bind to at least 20 linear epitope groups on VSV N-protein and over 25 linear epitope groups on 60 kd Ro protein. These antibodies also bound 5 of the 6 shared sequences between 60 kd Ro protein and VSV N-protein.

CONCLUSIONS

Our data demonstrate that an immune response initiated towards a foreign antigen, selected on the basis of sharing short sequence similarity with the autoantigenic epitopes of an autoantigen, can lead to an autoimmune response.

Neurotrophin regulation of energy homeostasis in the central nervous system

Our hypothesis is that one cause of neuronal cell death and shrinkage in the aged central nervous system is an inability of neurons to maintain oxidant homeostasis in the face of increased levels of reactive oxygen species, decreased endogenous antioxidants, and impaired energy metabolism associated with physiological senescence, Alzheimer's, and Parkinson's diseases. Since treatment with nerve growth factor (NGF) reverses behavioral impairments in aged rats and stimulates cholinergic activity in the basal forebrain, while brain-derived neurotrophic factor appears to play a similar role in the striatum, we propose that neurotrophin-mediated cell-sparing reflects effects on oxidant homeostasis. Neurotrophins may play a similar cell-sparing role in hypoxic/ischemic injury to the nervous system, which also is mediated in part by reactive oxygen species. The degradation of one such species, H2O2, is catalyzed by catalase and glutathione peroxidase (GSH Px). The activity of the latter enzyme is dependent on glutathione reductase and the availability of NADPH for regeneration of reduced GSH. The GSH redox cycle is also regulated by enzymes of the hexose monophosphate shunt. NGF protects PC12 cells from H2O2 injury by stimulating the synthesis of antioxidant enzymes including catalase, GSH Px, glucose-6-phosphate dehydrogenase, and gamma-glutamylcysteine synthetase, the rate-limiting enzyme for glutathione synthesis. NGF also enhances recovery from the NAD+ losses occurring as a consequence of H2O2 treatment.

Role of nerve growth factor in oxidant homeostasis: glutathione metabolism

Free radicals are generated in the CNS by ongoing oxygen metabolism and biological events associated with injury and inflammation. Increased free radical levels may also persist in some chronic neurological diseases and in the aged. Nerve growth factor (NGF) is a member of the neurotrophin family of proteins that can regulate neuronal development, maintenance, and recovery from injury. NGF protected rat pheochromocytoma PC12 cells, an adrenal chromaffin-like NGF-responsive cell line, from the oxidant stress accompanying hydrogen peroxide treatment by stimulating GSH levels and enzymes in the GSH metabolism cycle and in the GSH/GSH peroxidase antioxidant redox system, a ubiquitous cellular antioxidant system. Specifically, NGF increased gamma-glutamylcysteine synthetase (GCS) activity, the rate-limiting enzyme for GSH synthesis, by 50% after 9 h and GSH levels by 100% after 24 h of treatment. NGF stimulated GSH peroxidase by 30% after 3 days and glucose 6-phosphate dehydrogenase by 50% after 2 days. Treatment with NGF and cycloheximide, or actinomycin D, which inhibit protein and RNA synthesis, respectively, blocked the NGF stimulation of GCS and glucose 6-phosphate dehydrogenase. Increased GSH levels due to NGF treatment were responsible for the significant protection of PC12 cells from hydrogen peroxide-induced stress. Pretreatment of PC12 cells with NGF for 24 h rescued cells from the toxic effects of the extracellular hydrogen peroxide generated by the glucose/glucose oxidase system but did not rescue cells that were subjected to GSH deprivation due to treatment with 10 microM L-buthionine-(S,R)-sulfoximine, an inhibitor of GCS.(ABSTRACT TRUNCATED AT 250 WORDS)

Tunable dual-wavelength continuous-wave diode laser operated at 830 nm

An external grating cavity semiconductor diode laser is made to operate simultaneously at two separately adjustable wavelengths. Lasing is restricted to the vicinity of the solitary laser 6talon resonances.

Tunable external cavity diode laser that incorporates a polarization half-wave plate

The threshold current and specttal properties of a grating tuned external cavity semiconductor laser are improved by utilizing an intracavity half-wave plate to optimize the grating feedback.

Production of hybrid bispecific antibody recognizing human colorectal carcinoma and CD3 antigen

The present study reports on the use of gene transfer by vector DNA in the generation of hybrid hybridoma, the quadroma secreting the hybrid bispecific antibody. A quadroma B72.3neo/OKT3gpt was simply derived from the fusion of two hybridoma cell lines, B72.3 and OKT3, tagged with vector DNA mpSV2neo and mpSV2gpt, respectively, and selected in the media containing both G418 and mycophenolic acid. The hybrid bispecific antibody B72.3/OKT3 was purified from the quadroma ascites by the use of hydroxylapatite column on high-pressure liquid chromatography. This bispecific antibody contained one binding site for the TAG72 antigen on OVCAR3 tumor cells and the other binding site for the CD3 molecule on human T cells. It was able to target human T lymphocytes to significantly lyse the human ovarian cancer cells and may therefore be useful in immunotherapy of cancer.

[The determination and evaluation of the plasma amino acid in respiratory failure]

The measurement of the plasma amino acid was made in 15 patients with chronic respiratory failure and 15 persons of control. The results showed: (1) The plasma acid model changed. Lysine increases and arginine decreases, due to hypothermia. Hypercapnia imbalance of acid and alkali and changes of hepatic dysfunction etc. (2) The prognosis of respiratory failure as well as its severity was judged according to the decreasing extent of arginine and BCAA. The more worse the condition of the disease, the more lowering of the level of arginine and BCAA. (3) The changes of blood gas analysis and hepatic dysfunction may effect on the metabolism of plasma amino acid in some degree. (4) Hypoxemia in infected patients with respiratory failure may cause peripheral deficit of energy. We suggested that patients should be given BCAA and arginine for more energy as anti-infection and oxygen therapy were used.

[Effects of stenosis on blood flow in the coronary artery of dogs]

The effects of stenosis on coronary blood flow (CBF) were studied in 22 open-chest mongrel dogs. A progressive stenosis was produced by a micrometer constrictor on the left circumflex coronary artery. Mean aortic pressure (Pa), distal coronary pressure (Pc) and stenotic segment pressure drop (delta P) were measured. Curve of CBF versus % stenosis showed that CBF was relatively constant with stenosis less than 85%, CBF rapidly decreased with stenosis of 85-95%, and then slowly reduced as stenosis was further increased. The change in CBF versus % stenosis was expressed as follows: CBF = 1.48 X 10(10) theta -27.6 A (where A = % stenosis in lumen area). With progressive coronary artery stenosis (greater than 75%), the change in percent stenosis and Pc showed a negative correlation: Pc = 159.1-1.36A (r = -0.73, P less than 0.01); the change in Pc and CBF showed a positive correlation: Pc = 16.9 + 1.3 CBF (r = 0.74, P less than 0.01).