PubMed Health⌕ Search

Biomedical subjects

M Roghani

Publications and source records attributed to M Roghani.

At least 19 recordsLinked to original sources
PubMed2003

Endothelium-dependent and -independent effect of aqueous extract of garlic on vascular reactivity on diabetic rats.

Garlic has been well known for its protective effects against cardiovascular disease. In this study, the effect of aqueous extract of garlic on the vascular reactivity of thoracic aorta from streptozotocin (STZ)-diabetic rats was investigated in the presence and absence of endothelium. Although, 8-weeks of treatment with garlic extract had no significant effect on the concentration of serum glucose, but it significantly attenuated the abnormality in vascular reactivity to noradrenaline (NA) and acetylcholine (Ach). In addition, the endothelium-independent relaxation response to isosorbide dinitrate (ISD) was not affected by diabetes or garlic treatment. The results suggest that garlic treatment of STZ-diabetic rats can prevent the development of abnormal contractility through an endothelium-dependent and -independent mechanism.

Acetylcholine↗
PubMed2001

Neuroprotective effect of vitamin E on the early model of Parkinson's disease in rat: behavioral and histochemical evidence.

There is strong evidence that oxidative stress participates in the etiology of Parkinson's disease (PD). We designed this study to investigate the neuroprotective effect of vitamin E in the early model of PD. For this purpose, unilateral intrastriatal 6-hydroxydopamine (12.5 microg/5 microl) lesioned rats were pretreated intramuscularly with D-alpha-tocopheryl acid succinate (24 I.U./kg, i.m.) 1 h before and three times per week for 1 month post-surgery. Apomorphine- and amphetamine-induced rotational behavior was measured postlesion fortnightly. A parallel tyrosine hydroxylase immunoreactivity and wheat germ agglutinin-horse radish peroxidase (WGA-HRP) tract-tracing study was performed to evaluate the vitamin E pretreatment efficacy. Tyrosine hydroxylase-immunohistochemical analyses showed a reduction of 18% in ipsilateral substantia nigra pars compacta (SNC) cell number of the vitamin E-pretreated lesioned (L+E) group comparing with contralateral side. The cell number dropped to 53% in the lesioned (L+V) group. In addition, retrograde-labeled neurons in ipsilateral SNC were reduced by up to 30% in the L+E group and 65% in the L+V group. Behavioral tests revealed that there are 74% and 68% reductions in contraversive and ipsiversive rotations in the L+E group, respectively, as compared with the L+V group. Therefore repeated intramuscular administration of vitamin E exerts a rapid protective effect on the nigrostriatal dopaminergic neurons in the early unilateral model of PD.

Amphetamine↗
PubMed2000

Fibroblast growth factor (FGF)-2 mediates cell attachment through interactions with two FGF receptor-1 isoforms and extracellular matrix or cell-associated heparan sulfate proteoglycans.

In the presence of FGF-2, cells in suspension expressing FGF receptor-1 will attach to monolayers of cells expressing heparan sulfates. This attachment provides physical evidence for the formation of a trimolecular complex between FGF-2, heparan sulfate, and FGF receptors. We have used this system to determine if receptor isoforms containing or lacking the first of three immunoglobulin-like domains are equally able to form complexes with FGF-2 and heparan sulfates. In the presence of FGF-2, cells expressing either isoform of the receptor were able to attach to monolayers of CHO cells expressing heparan sulfates. No attachment was observed in the absence of FGF-2 or if heparin was included in the incubation medium. Attachment of cells expressing the two receptor isoforms occurred at similar concentrations of FGF-2, and similar concentrations of heparin were required to disrupt the interactions. Thus, there appeared to be little difference between these receptor isoforms in their ability to form trimolecular complexes with FGF-2 and cell-associated heparan sulfates. We also found that, in the presence of FGF-2, cells expressing FGF receptor-1 are able to form complexes with both extracellular matrix and cell-surface heparan sulfates.

Animals↗
PubMed1999

Metalloprotease-disintegrin MDC9: intracellular maturation and catalytic activity.

Metalloprotease disintegrins are a family of membrane-anchored glycoproteins that are known to function in fertilization, myoblast fusion, neurogenesis, and ectodomain shedding of tumor necrosis factor (TNF)-alpha. Here we report the analysis of the intracellular maturation and catalytic activity of the widely expressed metalloprotease disintegrin MDC9. Our results suggest that the pro-domain of MDC9 is removed by a furin-type pro-protein convertase in the secretory pathway before the protein emerges on the cell surface. The soluble metalloprotease domain of MDC9 cleaves the insulin B-chain, a generic protease substrate, providing the first evidence that MDC9 is catalytically active. Soluble MDC9 appears to have distinct specificities for cleaving candidate substrate peptides compared with the TNF-alpha convertase (TACE/ADAM17). The catalytic activity of MDC9 can be inhibited by hydroxamic acid-type metalloprotease inhibitors in the low nanomolar range, in one case with up to 50-fold selectivity for MDC9 versus TACE. Peptides mimicking the predicted cysteine-switch region of MDC9 or TACE inhibit both enzymes in the low micromolar range, providing experimental evidence for regulation of metalloprotease disintegrins via a cysteine-switch mechanism. Finally, MDC9 is shown to become phosphorylated when cells are treated with the phorbol ester phorbol 12-myristate 13-acetate, a known inducer of protein ectodomain shedding. This work implies that removal of the inhibitory pro-domain of MDC9 by a furin-type pro-protein convertase in the secretory pathway is a prerequisite for protease activity. After pro-domain removal, additional steps, such as protein kinase C-dependent phosphorylation, may be involved in regulating the catalytic activity of MDC9, which is likely to target different substrates than the related TNF-alpha-convertase.

ADAM Proteins↗
PubMed1996

Induction of urokinase-type plasminogen activator by fibroblast growth factor (FGF)-2 is dependent on expression of FGF receptors and does not require activation of phospholipase Cgamma1.

The roles of heparan sulfate proteoglycans and tyrosine kinase fibroblast growth factor (FGF) receptors in mediating the induction of plasminogen activator (PA) by FGF-2 were investigated using L6 myoblast cells that normally do not express detectable FGF receptors. PA was induced by FGF-2 in a dose-dependent manner in L6 cells expressing transfected FGF receptor-1 but not in nontransfected cells or cells transfected with the vector alone. The PA produced in these cells was characterized as urokinase-type PA (uPA). Thus, expression of a tyrosine kinase FGF receptor was required for induction of uPA. Internalization of FGF through heparan sulfates does not seem to be involved in this response as soluble heparin and suramin at concentrations which inhibited FGF-2 binding to heparan sulfates but not receptors did not affect the induction of uPA by FGF-2. Mutant receptors in which the tyrosine kinase was inactivated were not able to respond to FGF-2. In contrast, mutation of the site of phospholipase Cgamma1 (PLCgamma) binding in the receptor, which causes loss of PLCgamma activation, had no effect on uPA induction by FGF-2. These results suggest that PLCgamma activation is not required for induction of uPA by FGF-2.

Chlorates↗
PubMed1995

FGF suppresses apoptosis and induces differentiation of fibre cells in the mouse lens.

To determine whether fibroblast growth factor (FGF) has a role in lens development, we have generated transgenic mice expressing a dominant-negative form of the murine FGF receptor-1 (FGFRDN) in the lens. Using the fibre cell-specific alpha A-crystallin promoter to express the FGFRDN, we have asked whether FGF is required for fibre cell differentiation. The transgenic mice display diminished differentiation of fibre cells as indicated by their reduced elongation. In addition, transgenic lenses have an unusual refractile anomaly that morphological and biochemical data show results from the apoptosis of fibre cells in the central region of the lens. These results show that lens fibre cells are dependent on FGF for their survival and differentiation, and demonstrate that growth factor deprivation in vivo can lead to apoptosis.

Animals↗
PubMed1994

Heparin increases the affinity of basic fibroblast growth factor for its receptor but is not required for binding.

The role of heparin or heparan sulfates in the interaction of basic fibroblast growth factor (bFGF) with its high affinity receptor were investigated using purified extracellular ligand-binding region of FGF receptor-1 (FGFR-1) and intact receptors expressed in a myeloid cell line (32D) that does not express detectable levels of heparan sulfate proteoglycans or in Chinese hamster ovary (CHO) cell mutants defective in heparan sulfate synthesis. The purified extracellular domain of FGFR-1 formed complexes with 125I-bFGF both in the presence or absence of heparin. Intact FGFR-1 expressed in 32D cells also bound the same amount of 125I-bFGF in the presence or absence of heparin when saturating concentrations of bFGF were used. Varying the concentration of 125I-bFGF showed that heparin increased the amount of 125I-bFGF bound at low bFGF concentrations and increased the affinity of bFGF for its receptor by about 3-fold. To eliminate the possibility of alteration of bFGF properties through the chemical modification reactions, bFGF was labeled biosynthetically. The binding of biosynthetically labeled bFGF to FGFR-1 also did not require heparin. When FGFR-1 or FGFR-2 were expressed in mutant CHO cells deficient in heparan sulfate synthesis, the cells also bound 125I-bFGF in the absence of heparin, and the addition of heparin increased the affinity of bFGF for its receptors 2-3-fold. Thus, heparin or heparan sulfate is not required for the binding of bFGF to its receptors but increases the binding affinity to a moderate degree. Finally, the requirement for heparin in signal transduction through the receptor was investigated. Expression of c-fos mRNA was induced by bFGF in 32D cells expressing FGFR-1 to the same extent in the presence or absence of heparin.

Animals↗
PubMed1994

Studies on FGF-2: nuclear localization and function of high molecular weight forms and receptor binding in the absence of heparin.

Multiple forms of FGF-2 have been shown to exist in many cell types. These different species of molecular masses of 18, 21.5, 22, and 24 kDa are all translated via the use of alternate initiation codons. The three forms of HMW FGF-2 initiate at CUGs codons, whereas the 18 kDa form initiates at an AUG codon. The entire 18 kDa sequence is contained within the larger forms of HMW FGF-2 as the AUG codon is 3' to the CUG codons. Although the 18 kDa form FGF-2 is localized primarily in the cytosol, a significant fraction of the HMW FGF-2 has a nuclear location. The nuclear localization of HMW FGF-2 is determined by amino acid residues in the amino-terminal extended sequence. The residues required for nuclear localization appear to be RG repeats that are found at multiple sites within the amino-terminal extension of HMW FGF-2. The nuclear localization of HMW FGF-2 suggested that these species may have unique properties. By selecting permanent transfectants of 3T3 cells expressing HMW, 18 kDa FGF-2, or all forms of FGF-2, we have found that HMW FGF-2 can endow cells with a phenotype different from that of cells expressing 18 kDa FGF-2. These cells are transformed by what appears to be the intracellular action of HMW FGF-2. The interaction of FGF-2 with heparin has also been examined.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1992

Basic fibroblast growth factor is internalized through both receptor-mediated and heparan sulfate-mediated mechanisms.

Basic fibroblast growth factor (bFGF) was internalized at a rapid rate by Chinese hamster ovary (CHO) cells that do not express significant numbers of high affinity receptors for bFGF as well as CHO cells that have been transfected with cDNA encoding FGF receptor-1 or FGF receptor-2. Internalization of bFGF was completely blocked by the addition of 10 micrograms/ml heparin in the parental CHO cells but only partially inhibited in cells expressing transfected FGF receptors. Bovine aortic endothelial cells also exhibit heparin-sensitive and heparin-resistant internalization of bFGF. The internalization of bFGF through the heparin-resistant pathway in CHO cells was efficiently competed by addition of unlabeled bFGF, was proportional to the number of receptors expressed, and approached saturation, suggesting that the heparin-resistant internalization was due to high affinity receptors. Internalization of bFGF through the heparin-sensitive pathway was not efficiently competed by unlabeled bFGF and did not approach saturation at concentrations of bFGF up to 50 ng/ml, properties similar to the interaction of bFGF with low affinity heparan sulfate binding sites on the cell surface. Internalization of bFGF in CHO cells not expressing FGF receptors was inhibited by heparin, heparan sulfate, and dermatan sulfate, the same glycosaminoglycans that block binding to cell-surface heparin sulfates. Internalization of bFGF in the parental CHO cells was inhibited at the same concentrations of heparin that block binding to cell-surface heparan sulfates. Finally, inhibition of the sulfation of CHO cell heparan sulfates by the addition of chlorate or digestion of CHO cell heparan sulfates with heparinase inhibited bFGF internalization in the parental CHO cells. These results demonstrate that bFGF can be internalized through a direct interaction with cell-surface heparan sulfates. Thus, there are two pathways for internalization of bFGF: high affinity receptor-mediated and heparan sulfate-mediated.

Animals↗
PubMed1991

Two insulin-like growth factor (IGF)-binding proteins are responsible for the selective affinity for IGF-II of cerebrospinal fluid binding proteins.

We have studied the relationships between the structure and affinity of two insulin-like growth factor-binding proteins (IGFBPs) purified from human cerebrospinal fluid (CSF). Competitive binding studies were performed using preparations of human recombinant IGF (rhIGF-I, rhIGF-II, and their labeled homologs) and the truncated variant form of IGF-I, rh-Des-(1-3)-IGF-I. One of these BPs, which is the most consistently detected in CSF, corresponds to IGFBP-2. The other is a new form whose N-terminal sequence we reported earlier, which we call the 32-30K BP on the basis of its electrophoretic migration. Comparisons were made with an IGFBP-1 preparation purified from amniotic fluid and with two BPs purified from human serum, which are homologous to the CSF BPs. The CSF BPs have particularly strong affinities for IGF-II. The estimated affinity constants (Ka) were 2 X 10(10) M-1 for IGFBP-2 and 10(11) M-1 for the 32-30K BP. These affinities were 15-20 and 70 times stronger than the respective affinities for IGF-I. The affinity of the 32-30K BP is the strongest among the BPs identified to date. The two BPs isolated from serum, which correspond to the 32-30K CSF BP and IGFBP-2, had affinities for IGF-II and IGF-I similar to those of the CSF BPs. IGFBP-1 had nearly identical affinities for the two IGFs of approximately 10(10) M-1. Des-(1-3)-IGF-I failed to bind to the CSF BPs, but bound to IGFBP-1, although with a 40-fold weaker affinity than IGF-I. From our data it would seem that IGFBP-1 has two classes of IGF-binding site, one of high and one of low (less than 10(9) M-1) affinity for both IGFs. The other two BPs, by contrast, each possess a predominant class of high affinity binding site for IGF-II. A second class of lower affinity (greater than 10(9) M-1) sites bind both IGF-I and IGF-II. In the case of the 32-30K BP, these preferentially bind IGF-II; in the case of IGFBP-2, their binding of the two IGFs is similar. These different types of binding site may play an important role in controlling the bioavailability of IGF-I and IGF-II.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Purification from human cerebrospinal fluid of insulin-like growth factor binding proteins (IGFBPs). Isolation of IGFBP-2, an altered form of IGFBP-3 and a new IGFBP species.

Cerebrospinal fluid insulin-like growth factor binding proteins (CSF IGFBPs) characteristically have a preferential affinity for IGF-II, which is largely accounted for by a 32-30 kDa IGFBP(Ka = 10(11) M-1) previously purified from human CSF, with an N-terminal sequence unlike any other IGFBP identified at the time. We have now used procedure (including ammonium sulphate precipitation, acidic gel filtration, affinity chromatography and reverse phase chromatography) and purified three further IGFBPs to homogeneity from child CSF. Apart from the 32-30-kDa form, the predominant IGFBP in CSF is a 34-kDa form (non-reduced in SDS-polyacrylamide gel electrophoresis). Like the 32-30-kDa IGFBP, it has a preferential affinity for IGF-II (Ka = 2 x 10(10) M-1). Its N-terminus, Phe-Arg-(/)-Pro-Pro-(/)-Thr-Pro-Glu-Arg-Arg-(/)-Gly-Pro-Pro-Pro-Val, corresponds to that deduced for IGFBP-2, except for the first three residues which were not found in the CSF IGFBP. Another form, of 30 kDa, has an N-terminus identical to IGFBP-3's over the first 18 residues determined and seems to be an altered form of IGFBP-3. A third minor species, of 22 kDa, with a preferential affinity for IGF-II similar to that of the 34-kDa IGFBP, has an N-terminal sequence, (/)-(/)-Asp-Ser-Phe-Val-Pro-(/)-Glu-Pro-Ser-Asp-Glu-Lys-Ala-Leu-Ser-(/)- (/)-Pro, which bears some analogy with those of other known human IGFBPs, particularly IGFBP-3 (7 homologous residues), and appears to be related to, but distinct from, other IGFBP species.

Amino Acid Sequence↗
PubMed1990

Evidence of enzymatic degradation of insulin-like growth factor-binding proteins in the 150K complex during pregnancy.

Western ligand blot analysis of the different molecular forms of insulin-like growth factor-binding protein IGF-BP) in serum and plasma samples from 89 pregnant women has revealed a marked decrease, after the second month of pregnancy, in the 41.5 and 38.5K species (which are the binding units of the 150K complex) as well as in the 24K form. There was also a slight decrease in the 34K form, the 30K form was unaffected, and additional 21.5 and 20K bands appeared. Cross-linking experiments demonstrated the disapperance of a 49K band which is characteristic of the 150K complex. The alterations of the electrophoretic profile of the BPs were accompanied by a decrease in binding activity of up to 90%. Gel filtration at pH 7.4 confirmed that the decrease was essentially attributable to changes in the 150K complex BPs: 1) material eluting in the 150K zone contained only one third of the binding activity, as opposed to three quarters in reference material; 2) radiocompetition experiments illustrated the loss of affinity for IGF-I and IGF-II of the BPs extracted from the 150K complex; 3) ligand blot analysis revealed, in contrast with the virtual disappearance of the 41.5 and 38.5K forms, the appearance of a broad indistinct band at 30K and additional bands at 21.5 and 20K. With immunoblotting, the anti-IGF-BP-3 antibody, which specifically recognizes the 41.5 and 38.5K species, cross-reacted with this 30K material. The alterations of the BPs appeared to be enzymatic. When pregnancy serum was mixed with reference serum, the 41.5, 38.5, and 24K forms contributed by the reference serum were markedly reduced after 30 min of incubation at 37 C. However, these alterations could be prevented by incubation at either 0 or at 37 C in the presence of EDTA or aprotinin and could be curbed in the presence of high concentrations of phenylmethylsulfonylfluoride. Unmixed reference serum incubated at 37 C yielded an unchanged BP profile. Incubation of pregnancy serum with hypopituitary serum, which has elevated levels of the 34 and 30K BPs, resulted in a marked decrease in the 41.5 and 38.5K forms, a slight alteration of the 34K form, and no change in the 30K form. These findings suggest that during pregnancy, enzymatic (probably protease) activity either appears or is significantly increased in the circulation, which specifically degrades some of the IGF-BPs.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Isolation from human cerebrospinal fluid of a new insulin-like growth factor-binding protein with a selective affinity for IGF-II.

In biological fluids IGF-I and IGF-II are bound to specific, high-affinity binding protein (BPs). Two human BPs have been isolated, one from serum, which is GH-dependent, the other from amniotic fluid (AF BP), and their cDNAs have recently been cloned. We report here the isolation of another, new species from cerebrospinal fluid (CSF) where this BP predominates. The protein was purified to homogeneity by a four-step procedure: gel filtration, chromatofocusing, hydrophobic-interaction chromatography and reverse-phase chromatography. Thereafter, SDS-polyacrylamide gel electrophoresis gave an Mr of 34,000 (non-reduced), chromatofocusing gave an isoelectric point of 5.0m and its affinity for IGF-II (3 x 10(10) M-1) was 10 times that for IGF-I. The N-terminal amino acid sequence of the first 15 residues determined in a BP preparation from the CSF of children was Leu-Ala-Pro-Gly-(/)-Gly-Gln-Gly-Val-Gln-Ala-Gly-Ala-Pro-Gly. A similar sequence was found for adult CSF, apart from residues 12 and 13 (-Leu-Leu-). These are highly analogous with the sequences starting from residue 69 of the GH-dependent BP, and from residue 61 of the AF BP. The new BP isolated is therefore related to, but distinct from, the other human BPs.

Adult↗
PubMed1989

Molecular forms of serum insulin-like growth factor (IGF)-binding proteins in man: relationships with growth hormone and IGFs and physiological significance.

Insulin-like growth factor-I (IGF-I) and IGF-II are associated in the blood with specific binding proteins (BPs), forming complexes that elute in gel filtration with estimated mol wt around 40 and 150 kD. The latter appears to be under GH control. Five molecular forms of BP (41.5, 38.5, 34, 30, and 24 kD) have been identified by Western blotting using 125I-labeled IGF. All five forms are present in the smaller complexes, but only the 41.5- and 38.5-kD forms are found in the larger complexes. In this study immunoblotting showed that the 41.5- and 38.5-kD forms were recognized by antibodies directed against the GH-dependent BP purified from human plasma, and the 30-kD form was recognized by antibodies directed against the BP purified from amniotic fluid. The 34- and 24-kD forms proved to be immunologically unrelated to the other three. In sera with large quantities of the 41.5- and 38.5-kD forms, an additional band was often observed immediately ahead of the migration front of the 30 kD band. This was recognized by the anti-GH-dependent BP antibody and probably corresponds to a degradation product of the 41.5- and 38.5-kD BPs. Serum 41.5- and 38.5-kD BPs have been found to be elevated in acromegaly, where GH hypersecretion causes increased IGF-I levels, and diminished in cases of genetic or idiopathic GH deficiency and defects of the GH receptor (Laron's syndrome), where both IGF-I and IGF-II are decreased, as well as in Pygmy adults and children who have isolated IGF-I deficiency. In all of these conditions, the proportions of the 34- and 30-kD forms were inversely related to those of the 41.5- and 38.5-forms. Under treatment, the BP profiles tended to return to normal. In cases of GH deficiency caused by a tumor, the BP profiles resembled those of hypopituitary or normal serum, depending on whether IGF levels were diminished or normal. It, therefore, seems that BP synthesis is coordinated with IGF-I synthesis and may not be directly GH dependent. The results of neutral pH gel filtration analysis of hypopituitary (idiopathic and tumoral) and normal sera point to a relationship between the levels of circulating IGFs and those of the 150-kD IGF-BP complex whose binding units are the 41.5- and 38.5-kD BPs. It, therefore, seems that the 150-kD complex controls the bioavailability of IGF-I and IGF-II.(ABSTRACT TRUNCATED AT 400 WORDS)

Acromegaly↗
PubMed1987

Tumor promoter chloroform is a potent protein kinase C activator.

The major interaction site for tumor-promoting phorbol esters is the calcium-activated, phospholipid-dependent protein kinase (protein kinase C), a key-element in signal transduction. Binding of phorbol esters results in enzyme activation which mediates, at least in part, the action of these agents. We have investigated the effects of tumor promoter chloroform on protein kinase C activity. Like thrombin and 12-O-tetradecanoylphorbol-13-acetate (TPA), chloroform was able to activate protein kinase C in intact rabbit platelets. In addition, chloroform stimulated enzyme activity as well as TPA binding capacity in cell-free system. Scatchard analysis of the data has shown that chloroform increased the number of phorbol ester binding sites. Structurally related compounds, carbon tetrachloride and methylene chloride, activated the enzyme similarly.

Animals↗