Ability of progesterone to reverse anti-androgen (hydroxyflutamide)-induced interference with the preovulatory LH surge and ovulation in PMSG-primed immature rats

In Exp. 1, PMSG was injected to 26-day-old prepubertal rats to induce ovulations. On Day 2 (2 days later, the equivalent of the day of pro-oestrus) they received at 08:00 h 5 mg hydroxyflutamide or vehicle and at 12:00 h 2 mg progesterone or testosterone or vehicle. Animals were killed at 18:00 h on Day 2 or at 09:00 h on Day 3. Progesterone but not testosterone restored the preovulatory LH surge and ovulation in hydroxyflutamide-treated rats. In Exp. 2, 2 mg progesterone or testosterone were injected between 10:30 and 11:00 h on Day 2, to advance the pro-oestrous LH surge and ovulation in PMSG-primed prepubertal rats. Injection of hydroxyflutamide abolished the ability of progesterone to advance the LH surge or ovulation. Testosterone did not induce the advancement of LH surge or ovulation. In Exp. 3, ovariectomized prepubertal rats implanted with oestradiol-17 beta showed significantly (P less than 0.01) elevated serum LH concentrations at 18:00 h over those observed at 10:00 h. Progesterone injection to these animals further elevated the serum LH concentrations at 18:00 h, in a dose-dependent manner, with maximal values resulting from 1 mg progesterone. Hydroxyflutamide treatment significantly (P less than 0.003) reduced the serum LH values in rats receiving 0-1 mg progesterone but 2 mg progesterone were able to overcome this inhibition. It is concluded that progesterone but not testosterone can reverse the effects of hydroxyflutamide on the preovulatory LH surge and ovulation. It appears that hydroxyflutamide may interfere with progesterone action in induction of the LH surge, suggesting a hitherto undescribed anti-progestagenic action of hydroxyflutamide.     

Lipid conformational nomenclature: a general method.

We propose a conformational nomenclature for amphiphilic lipid molecules that is general and compatible with the stereospecific numbering scheme, in contrast to earlier methods in which discrepancies with the sn-scheme lead to contradictory assignments of the absolute configuration of the system. The present method can be rationally extended to different classes of lipids, both natural and synthetic. It is simple and provides a convenient framework for conformational studies on widely varying classes of lipids.     

Lysosomal enzymes and microbicidal capacity of activated macrophage.

A relation was sought between acid phosphatase contents and the presence of tubercle bacilli inside the peritoneal exudate cells (PEC) of normal guinea pigs and those immunized with BCG. This was done to investigate the role lysosomal enzymes play in the microbicidal capacity of the cell. In both normal and immune animals tubercle bacilli were present only in those PEC that contained acid phosphatase. Cells without acid phosphatase did not contain bacilli. Thus, only activated cells ingested bacilli. Under the conditions of these experiments, macrophage activation, as indicated by the presence of acid phosphatase, was not related to the immune status of the animal. Similarly, stimulation by ingestion of tubercle bacilli was not significant. Also, the number of acid phosphatase grains/cell did not influence the number of bacilli/cell. Thus, the acid phosphatase content of the cell did not correlate with the number of bacilli inside the cell. It was concluded that acid phosphatase may not be one of the factors that contribute to the microbicidal capacity of the cell.     

Transforming growth factor-β inhibition of interleukin-1 activity involves down-regulation of interleukin-1 receptors on chondrocytes

Interleukin-1 (IL-1) plays an important role in cartilage destruction associated with inflammatory and degenerative arthritis because of its ability to induce matrix degrading enzymes. Previously, we have shown that the IL-1-induced chondrocyte protease activity was inhibited by transforming growth factor-β (TGF-β). In this paper, we show that TGF-β inhibits the IL-1-induced synthesis of collagenase and stromelysin by reducing the steady-state mRNA levels in rabbit articular chondrocytes. We further demonstrate that TGF-β-treated chondrocytes show reduced ¹²⁵I-IL-1 binding that returns to a normal level when TGF-β is removed from the culture medium. The inhibitory effect of TGF-β is observed for both naturally occurring as well as fibroblast growth factor (FGF)-inducible binding sites (receptors). Scatchard analysis of receptor—ligand interactions demonstrate that the reduced binding is due to a reduction in the number of receptors for IL-1 and is not due to changes in affinity. Affinity cross-linking studies suggest that control chondrocytes contain two major cross-linked bands of M_r =116 and 80 kDa and a minor band of M_r =100 kDa. FGF-treated cells show enhanced levels of all the bands, plus an additional 200-kDa band. TGF-β treatment of chondrocytes results in the reduction of all of these bands in both control as well as FGF-induced cells. These observations suggest that the ability of TGF-β to down-regulate the IL-1 receptor may be a mechanism by which it exerts its effects in antagonizing the IL-1 activity on chondrocytes.     

Quantitative protein changes in the hypothalamic neurons of pubertal male rats, castrated neonatally.

The effect of neonatal castration of male rats on the sexual differentiation of the hypothalamus at puberty was studied. Male rats were castrated on days 1, 5 and 7 after birth. Their brains were processed for study on days 83-85. The neurons and cell nuclei of the preoptic area, mediobasal and ventromedial nuclei were assessed for changes in cell and nuclear sizes and dry weight (calculated using interferometric methods). Neonatal castration resulted in size as well as dry weight increase in the neurons of the anterior and mediobasal hypothalamus. The dry weight increased by 34% (P less than 0.001) in the medial preoptic area, by 25% (P less than 0.001) in the arcuate neurons and by 22% (P less than 0.001) in the ventromedial nucleus. The cell nuclei exhibited perceptible weight increase too--in the medial preoptic area 68% (P less than 0.001); 55% in the arcuate neurons (P less than 0.001), and 39% in the ventromedial region. The weight and size increases in neonatally castrated males were equal to those of females of the same age. In rats castrated on day 7, the cell sizes and dry weights of the ventromedial nucleus increased but the cell nuclei exhibited only little change. It is assumed that the changes in the dry weight may be the result of increased synthetic processes in these groups of neurons which are connected with the tonic and cyclic release of gonadotropins. These changes also point to the hypothalamic differentiation shifting to the female type in the absence of the inducing effect of androgens.     

Signal Peptide Cleavage from GP5 of PRRSV: A Minor Fraction of Molecules Retains the Decoy Epitope,a Presumed Molecular Cause for Viral Persistence

Porcine reproductive and respiratory syndrome virus (PRRSV) is the major pathogen in the pig industry. Variability of the antigens and persistence are the biggest challenges for successful control and elimination of the disease. GP5, the major glycoprotein of PRRSV, is considered an important target of neutralizing antibodies, which however appear only late in infection. This was attributed to the presence of a “decoy epitope” located near a hypervariable region of GP5. This region also harbors the predicted signal peptide cleavage sites and (dependent on the virus strain) a variable number of potential N-glycosylation sites. Molecular processing of GP5 has not been addressed experimentally so far: whether and where the signal peptide is cleaved and (as a consequence) whether the “decoy epitope” is present in virus particles. We show that the signal peptide of GP5 from the American type 2 reference strain VR-2332 is cleaved, both during in vitro translation in the presence of microsomes and in transfected cells. This was found to be independent of neighboring glycosylation sites and occurred in a variety of porcine cells for GP5 sequences derived from various type 2 strains. The exact signal peptide cleavage site was elucidated by mass spectrometry of virus-derived and recombinant GP5. The results revealed that the signal peptide of GP5 is cleaved at two sites. As a result, a mixture of GP5 proteins exists in virus particles, some of which still contain the “decoy epitope” sequence. Heterogeneity was also observed for the use of glycosylation sites in the hypervariable region. Lastly, GP5 mutants were engineered where one of the signal peptide cleavage sites was blocked. Wildtype GP5 exhibited exactly the same SDS-PAGE mobility as the mutant that is cleavable at site 2 only. This indicates that the overwhelming majority of all GP5 molecules does not contain the “decoy epitope”.     

Anti-platelet activity of a three-finger toxin (3FTx) from Indian monocled cobra (Naja kaouthia) venom

A low molecular weight anti-platelet peptide (6.9 kDa) has been purified from Naja kaouthia venom and was named KT-6.9. MALDI-TOF/TOF mass spectrometry analysis revealed the homology of KT-6.9 peptide sequence with many three finger toxin family members. KT-6.9 inhibited human platelet aggregation process in a dose dependent manner. It has inhibited ADP, thrombin and arachidonic acid induced platelet aggregation process in dose dependent manner, but did not inhibit collagen and ristocetin induced platelet aggregation. Strong inhibition (70%) of the ADP induced platelet aggregation by KT-6.9 suggests competition with ADP for its receptors on platelet surface. Anti-platelet activity of KT-6.9 was found to be 25 times stronger than that of anti-platelet drug clopidogrel. Binding of KT-6.9 to platelet surface was confirmed by surface plasma resonance analysis using BIAcore X100. Binding was also observed by a modified sandwich ELISA method using anti-KT-6.9 antibodies. KT-6.9 is probably the first 3FTx from Indian monocled cobra venom reported as a platelet aggregation inhibitor.     

Modulation of PDGF mediated osteoblast chemotaxis by leukemia inhibitory factor LIF

Cell migration is a key event in tissue repair and remodeling. PDGF, a growth factor for multiple target cells, has been shown to be a potent chemoattractant for a variety of mesenchymal cells. However, it is likely that PDGF-mediated cell migration will be influenced by other cytokines that can be produced during physiological and pathological conditions. Leukemia inhibitory factor (LIF), a cytokine that is produced by a variety of cells including osteoblasts, may promote bone formation, but the mechanism is not known. Since osteoblasts are responsible for laying down new matrix during skeletal remodeling, in this report we have examined whether PDGF or LIF influences the migration of osteoblasts. Among several cytokines and growth factors tested, only PDGF was able to elicit a major chemotactic (directed migration) and a minor chemokinetic (random-migration) response in osteoblasts. LIF alone was not active in either chemotaxis or chemokinesis but when included with PDGF it caused a reduction in chemokinesis. Further, pretreatment of osteoblasts with LIF caused an increase in PDGF-driven chemotaxis. Finally, osteoblasts exposed briefly to LIF synthesized a higher level of non-collagenous proteins upon further treatment with PDGF. These observations are consistent with a role for LIF in promoting bone formation, both by influencing directional migration of osteoblasts and in laying down new matrix. © 1996 Wiley-Liss, Inc.     

The 5' flank of mouse H19 in an unusual chromatin conformation unidirectionally blocks enhancer-promoter communication

BACKGROUND: During mouse prenatal development, the neighbouring insulin-like growth factor II (Igf2) and H19 loci are expressed monoallelically from the paternal and maternal alleles, respectively. Identical spatiotemporal expression patterns and enhancer deletion experiments show that the Igf2 and H19 genes share a common set of enhancers. Deletion of a differentially methylated region in the 5' flank of the H19 gene partially relieves the repression of the maternal Igf2 and paternal H19 alleles in the soma. The mechanisms underlying the function of the 5' flank of the H19 gene are, however, unknown. RESULTS: Chromatin analysis showed that the 5' flank of the mouse H19 gene contains maternal-specific, multiple nuclease hypersensitive sites that map to linker regions between positioned nucleosomes. These features could be recapitulated in an episomal-based H19 minigene, which was propagated in human somatic cells. Although the 5' flank of the H19 promoter has no intrinsic silencer activity under these conditions, it unidirectionally extinguished promoter-enhancer communications in a position-dependent manner, without directly affecting the enhancer function. CONCLUSIONS: The unmethylated 5' flank of the H19 gene adopts an unusual and maternal-specific chromatin conformation in somatic cells and regulates enhancer-promoter communications, thereby providing an explanation for its role in manifesting the repressed state of the maternally inherited Igf2 allele.