Syntheses, molecular structures, and vibrational spectra of chloropentacarbonylrhodium(III) and -iridium(III) undecafluorodiantimonate(V), [Rh(CO)5Cl][Sb2F11]2 and [Ir(CO)5Cl][Sb2F11]2: an experimental and density functional study

The reactions of either bis(mu-chloro)tetracarbonyldirhodium(I), [Rh(CO)2(mu-Cl)]2, or chlorotricarbonyliridium(I), [Ir(CO)3Cl]n, in the conjugate Brønsted-Lewis superacid HF-SbF5 and in a CO atmosphere, produce [Rh(CO)5Cl][Sb2F11]2 or [Ir(CO)5Cl][Sb2F11]2, respectively. In these oxidative carbonylation reactions, antimony(V) fluoride functions as an oxidizing agent. The reduced product is identified as 6SbF3.5SbF5. [Rh(CO)5Cl][Sb2F11]2 is obtained in the form of single crystals. Crystal data: monoclinic, space group P2(1) (No. 4); a = 9.721(1), b = 12.602(1), c = 10.538(1) A; beta = 106.51(1) degrees; V = 1237.7(2) A3; Z = 2; T = 300 K; R1 [I > 3 sigma (I)] = 0.0367, wR2 = 0.0739. Single crystals of [Ir(CO)5Cl][Sb2F11]2 are produced in small amounts from a solution of mer-Ir(CO)3(SO3F)3 in magic acid, HSO3F-SbF5. The possible source of chlorine will be discussed. Crystal data for [Ir-(CO)5Cl][Sb2F11]2: monoclinic, space group P2(1) (No. 4); a = 9.686(2), b = 12.585(2), c = 10.499(2) A; beta = 106.59(2) degrees; V = 1226.5(4) A3; Z = 2; T = 294 K; R1[I > 3 sigma (I)] = 0.032, Rw = 0.031. The bond lengths and bond angles are nearly identical in the two isostructural salts; however, the cell volume of [Ir(CO)5Cl][Sb2F11]2 is slightly smaller than that of [Rh(CO)5Cl][Sb2F11]2. The cations (point group C4v) feature unusually long M-C bonds (M = Rh, Ir) and correspondingly short CO bonds, as well as high CO stretching wavenumbers and high CO stretching force constants. The [Sb2F11]- anions are not symmetry related, and their dihedral and bridge angles differ slightly in both salts. There are significant interionic contacts in [Ir(CO)5Cl][Sb2F11]2 exclusively of the C-F type (about 2 for each C atom of the five carbonyl groups) resulting in extended structures. The vibrational spectra for both [M(CO)5Cl]2+ cations (M = Rh, Ir) are assigned with the help of density functional calculations, which also provide intensities for IR and Raman bands. While [Rh(CO)5Cl]2+ is the first cationic carbonyl derivative of Rh(III), the vibrational and structural parameters for [Ir(CO)5Cl]2+ are compared to data for [Ir(CO)6]3+ and mer-Ir(CO)3(SO3F)3.

[Impact of a selective screening for gestational diabetes in a Spanish population]

BACKGROUND

Recently, the American Diabetes Association (ADA) concluded that pregnant women with low risk factors for gestational diabetes need not to be tested. The aims of this study was to determine the prevalence of gestational diabetes in a Spanish low risk pregnant women population, to analyze the criteria that define low risk pregnancies for gestational diabetes, and to compare the differences in morbidity between pregnant women with and without gestational diabetes.

DESIGN AND METHODS

Cohort study of 2,262 gestations (2,085 Caucasians) during a period of 7 years in a reference hospital.

RESULTS

The gestational diabetes prevalence was 15%. Two-hundred and seventy-four (12.1%) women were considered as a low risk group for gestational diabetes. Among these, 13 (4.7%) presented gestational diabetes in comparison with 16.6% in the remaining women (p = 0.0001). Gestational diabetes in the low risk pregnant women constituted the 3.8% of all gestational diabetes. We did not find differences in gestational outcomes or fetal antropometry between the groups. The relative risk of macrosomia in the low risk pregnant was 0.9% (95% confidence interval for the mean: 0.86-0.94).

CONCLUSIONS

In spite of their capacity of identifying current complications, 4% of gestational diabetes would not have been diagnosed with the new ADA criteria. The misdiagnosis will prevent in this small group of women the adoption of preventive measures for subsequent pregnancies and for diabetes in later life.

Atrial natriuretic peptide clearance receptor participates in modulating endothelial permeability

The atrial natriuretic peptide (ANP)-C receptor is generally believed to clear ANP; however, the ANP-C receptor may serve to reduce cAMP by inhibiting adenylate cyclase. ANP decreases endothelial permeability in coronary endothelial cell monolayers. We tested the hypothesis that part of this effect might be mediated by the ANP-C receptor. We used an endothelial cell monolayer from rat coronary endothelium and measured albumin flux. We applied either ANP or a ring-deleted ANP (C-ANP), which only stimulates the ANP-C receptor. ANP and C-ANP both decreased permeability from 100 pM to 100 nM by 60 and 30%, respectively. ANP increased endothelial cGMP contents 5.5-fold, whereas C-ANP had no effect. ANP reduced endothelial cAMP contents by 75%, which was only partly blocked by pertussis toxin. C-ANP also reduced cAMP; however, this effect was completely blocked by pertussis toxin. Protein kinase G inhibition blocked the ANP-mediated decrease in permeability by 50%. In contrast, pretreatment with pertussis toxin, in the face of protein kinase G inhibition, blocked the effect completely. C-ANP decreased permeability by half the amount of ANP. This C-ANP effect was completely blocked by pertussis toxin but not by protein kinase G inhibition. Isoproterenol (10 microM) increased permeability by almost 50%, which was completely blocked by ANP but only partially blocked by C-ANP. The C-ANP effect was blocked completely by pertussis toxin. Isoproterenol increased cAMP threefold, which was abolished by ANP. C-ANP reduced the isoproterenol-induced increase in cAMP by 50%. Isoproterenol had no effect on cGMP. We conclude that agonist binding to the ANP-C receptor inhibits cAMP production via a Gi protein-coupled signaling system. This inhibition may contribute to the decreased endothelial permeability evoked by ANP in this system.

Molecular cloning, genomic characterization and expression of novel human alpha1A-adrenoceptor isoforms

We have isolated and characterized from human prostate novel splice variants of the human alpha1A-adrenoceptor, several of which generate truncated products and one isoform, alpha(1A-4), which has the identical splice site as the three previously described isoforms. Long-PCR on human genomic DNA showed that the alpha(1A-4) exon is located between those encoding the alpha(1A-1) and alpha(1A-3) variants. CHO-K1 cells stably expressing alpha(1A-4) showed ligand binding properties similar to those of the other functional isoforms as well as agonist-stimulated inositol phosphate accumulation. Quantitative PCR analyses revealed that alpha(1A-4) is the most abundant isoform expressed in the prostate with high levels also detected in liver and heart.

Expression of human dopamine beta-hydroxylase in Drosophila Schneider 2 cells

Human dopamine beta-hydroxylase (DBH) has been expressed in transformed Drosophila Schneider 2 (S2) cells with yields of > 16 mg/l. Most of the activity was found in the culture fluid. Similarly, human neuroblastoma cells also secrete native DBH into the medium, but at a much lower level than recombinant Drosophila cells. We have purified native and recombinant human DBH by a modified purification procedure using SP-Sepharose, lentil lectin-Sepharose and gel-filtration chromatography and carried out studies to compare the two enzymes. Two variants of human DBH that differ by a single amino acid (either serine or alanine) at position 304 were expressed in Drosophila cells, purified, and found to have no significant difference in enzyme activity. The molecular mass of human DBH monomer has been determined from SDS/PAGE to be 73 kDa, but the recombinant DBH from Drosophila is smaller at 66 kDa. The difference may be due to glycosylation as deglycosylated enzymes from both sources are identical in size (61 kDa). The Km of tyramine for native and recombinant human enzymes are virtually the same but higher than bovine DBH by about 3-fold. Likewise, the inhibition of native and recombinant human DBH by fusaric acid and SKF102698 is not significantly different but IC50 values are 2-3-fold higher than that for the bovine enzyme. These results strongly support the conclusion that recombinant human DBH from Drosophila S2 cells can be used in place of human neuroblastoma-derived DBH for drug screening, characterization of the enzyme's physicochemical properties, and determination of structure-function relationships. The Drosophila expression system has thus provided a convenient source for large quantities of human DBH enzyme.

The pharmacology and distribution of human 5-hydroxytryptamine2B (5-HT2B) receptor gene products: comparison with 5-HT2A and 5-HT2C receptors

1. Full length clones of the human 5-HT2B receptor were isolated from human liver, kidney and pancreas. The cloned human 5-HT2B receptors had a high degree of homology (approximately 80%) with the rat and mouse 5-HT2B receptors. 2. PCR amplification was used to determine the tissue distribution of human 5-HT2B receptor mRNA. mRNA encoding the 5-HT2B receptor was expressed with greatest abundance in human liver and kidney. Lower levels of expression were detected in cerebral cortex, whole brain, pancreas and spleen. Expression was not detected in heart. 3. Northern blot analysis confirmed the presence of 5-HT2B receptor mRNA (a 2.4 kB sized band) in pancreas, liver and kidney. An additional 3.2 kB sized band of hybridization was detected in liver and kidney. This raises the possibility of a splice variant of the receptor or the presence of an additional homologous receptor. 4. The human 5-HT2B receptor was expressed in Cos-7 cells and its ligand binding characteristics were compared to similarly expressed human 5-HT2A and 5-HT2C receptors. The ligand specificity of the human 5-HT2B receptor (5-HT > ritanserin > SB 204741 > spiperone) was distinct from that of the human 5-HT2A (ritanserin > spiperone > 5-HT > SB 204741) and 5-HT2C (ritanserin > 5-HT > spiperone = SB 204741) receptors. On the basis of a higher affinity for ketanserin and a lower affinity for yohimbine the human 5-HT2B receptor also appeared to differ from the rat 5-HT2B receptor. 5. These findings confirm the sequence of the human 5-HT2B receptor and they demonstrate that the receptor has a widespread tissue distribution. In addition, these data suggest that there are differences in ligand affinities between different species homologues of the receptor. Finally, the finding of two distinct bands on the Northern blots of liver and kidney raises the possibility of splice variants or subtypes of 5-HT2B receptors, within these tissues.

Effect of methyltransferase inhibitors on the regulation of baculovirus protein synthesis

In the presence of the methyltransferase inhibitor 3-deazaadenosine (3DA-Ado) the production of infectious Autographa californica nuclear polyhedrosis virus (AcMNPV) in tissue culture was only slightly affected, while the synthesis of very late proteins (polyhedrin and p10) was abolished. The synthesis of the influenza virus proteins NS1 and HA, expressed under the polyhedrin promoter, was also abolished by 3DA-Ado. Furthermore, 3DA-Ado interfered with the shut-off of early and late AcMNPV proteins. Most of these results were also obtained with 5-azadeoxycytidine (5A-dCyt). In cells in which NS1 was produced abundantly, at least one specific AcMNPV protein was not synthesized. However, if the production of NS1 was inhibited by 3DA-Ado, or if HA was synthesized instead, this AcMNPV protein showed up normally.

Purification, characterization and selective inhibition of human prostaglandin G/H synthase 1 and 2 expressed in the baculovirus system

Human prostaglandin G/H synthase 1 and 2 were expressed in the baculovirus expression system and purified to high levels. Both enzymes were glycosylated. PGHS-1 appeared to be homogeneous by SDS-PAGE analysis but two closely migrating bands were detected in PGHS-2 preparation which were evidently due to heterogeneity in glycosylation. The amino-acid sequence of the N-termini of both isoforms indicated that the signal sequences were efficiently cleaved by the insect cells. The recombinant human PGHS-1 and PGHS-2 possessed both cyclooxygenase and peroxidase activities. Both had high affinities for arachidonate as substrate and underwent self-inactivation during catalysis. The recombinant isoforms were not pharmacologically identical, since some NSAIDs were selective inhibitors of either PGHS-1 or PGHS-2. This is the first report of high levels of expression and purification of human PGHS isoforms. The recombinant enzymes are invaluable in developing potent PGHS-2 selective inhibitors that may be efficacious anti-inflammatory drugs with no or low levels of toxicity.

Cloning and expression of a 5-hydroxytryptamine7 receptor positively coupled to adenylyl cyclase

A cDNA clone (designated as GP2-7) encoding a novel 5-hydroxytryptamine (5-HT) receptor was isolated from a guinea pig hippocampal library. The receptor shares amino acid homology within the hydrophobic domains with other cloned 5-HT receptor subtypes (34-48%). The sequence of GP2-7 is homologous to that described for a novel receptor previously cloned from a rat brain cDNA library and provisionally designated as 5-HT7. mRNA for GP2-7 was detected in cortical and limbic brain regions. Transiently expressed GP2-7 showed high-affinity binding to [3H]5-HT (pKi = 9.0) with the following rank order of affinities: 5-carboxyamidotryptamine (5-CT) > 5-HT = 5-methoxytryptamine (5-MeOT) > methiothepin > 8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT) > spiperone >> sumatriptan. Adenylyl cyclase activity in CHO-K1 cells transiently transfected with GP2-7 was stimulated by several analogues of 5-HT with the following order of potency: 5-CT > 5-HT = 5-MeOT > dipropyl-5-CT > 8-OH-DPAT. Methiothepin and spiperone were potent antagonists. Preliminary analysis suggests that GP2-7 closely resembles a receptor in the guinea pig hippocampus that exhibits a high affinity toward 5-CT.

Bradykinin-B2 receptors in humans and rats: cDNA structures, gene structures, possible alternative splicing, and homology searching for subtypes

1. To identify and isolate cDNAs encoding rat and human bradykinin-B2 receptor subtypes we isolated a human bradykinin receptor cDNA homologous to a rat B2 receptor cDNA. 2. The cDNA was expressed in the bradykinin receptor negative cell line, CHO; membranes prepared from these cells bound bradykinin and had specificity similar to that of the known rat B2 receptor. In addition, the expressed receptor has a low affinity for des-Arg9-bradykinin. Thus, the cDNA encodes a human B2-bradykinin receptor. 3. Comparison of the human and rat cDNAs suggested that the human and rat genes are composed of three exons. Cloning, sequencing and characterization of parts of the human and rat B2-bradykinin receptor genes demonstrated the postulated three-exon structure. This structure includes two 5' exons upstream of the most favorable translation initiation methionine in exon-3. 4. The two 5' exons each contain methionines, which if independently spliced to the third exon, would yield an open reading frame that includes all of exon-3. This arrangement could thus vary the amino-terminal region of the protein. Do these potential arrangements occur in human RNAs, and will they lead to proteins with differing amino-termini? 5. Reverse transcriptase-polymerase chain reactions (RT-PCR) using human mRNA, nested primers from exon-1 and exon-3, and detection of the products by hybridization using an independent exon-1 oligonucleotide showed that the arrangement of exon-1 with exon-2 and exon-3 could not be detected in eight human RNAs. Furthermore, exon-1 spliced with exon-3 was a common arrangement. 6. Low stringency examination of human and rat Southern blots revealed only bands attributable to the known human or rat B2-bradykinin receptor. 7. Reduced stringency hybridization searches of seven different genomic and cDNA libraries--including two different human genomic libraries, a rat genomic library, two different rat uterus cDNA libraries, a rat brain library and a human lung library--yielded only rat or human B2-bradykinin receptors. The results of our low stringency hybridization experiments suggest that other bradykinin receptors are less than 60% identical, on the nucleotide level, to the known B2 receptor. 8. Degenerate polymerase chain reactions using rat genomic DNA as a template and degenerate primers, designed based on the homology of a B2-bradykinin receptor with angiotensin-II type-1 receptor, identified B2-bradykinin receptors, angiotensin-II-type-1 receptors and three novel orphan receptors.

Structure of influenza virus RNP. I. Influenza virus nucleoprotein melts secondary structure in panhandle RNA and exposes the bases to the solvent

The influenza virus genome consists of eight segments of negative-sense RNA, i.e. the viral (v) RNA forms the template for the mRNA. Each segment is encapsidated by the viral nucleoprotein to form a ribonucleoprotein (RNP) particle and each RNP carries its own polymerase complex. We studied the interaction of purified nucleoprotein with RNA in vitro, by using a variety of enzymatic and chemical probes for RNA conformation. Our results suggest that the nucleoprotein binds to the vRNA backbone without apparent sequence specificity, exposing the bases to the outside and melting all secondary structure. In this way, the viral polymerase may transcribe the RNA without the need for dissociating the nucleoprotein and without being stopped by RNA secondary structure, and the viral RNPs are ready to start transcription as soon as they enter the host cell.

Isolation of a cDNA encoding a human rolipram-sensitive cyclic AMP phosphodiesterase (PDE IVD)

cDNAs encoding human family-IV phosphodiesterase, subtype D (hPDE IVD) were isolated from a human heart cDNA library. The overlapping cDNAs encode a polypeptide of 604 amino acids (aa) with a predicted M(r) of 68,502, which is 91.4% identical to the rat homolog, rPDE IVD. hPDE IVD produced in Escherichia coli was inhibited by rolipram. Expression of the hPDE IVD mRNA is widespread in human tissues and most abundant in skeletal muscle.

The cDNA of a human lymphocyte cyclic-AMP phosphodiesterase (PDE IV) reveals a multigene family

Five protein families are needed to encompass the diversity of cyclic-AMP (cAMP) phosphodiesterases (PDE). Family IV PDEs (PDE IV) specifically hydrolyze cAMP with a low Km, and are selectively inhibited by rolipram (Rp) and related drugs. Cloned cDNAs from rat (r) suggest that the PDE IV family comprises four distinct members, designated A, B, C and D. Using RN from a human lymphocytic B-cell line (43D-Cl2), we have isolated a 3.8-kb cDNA by low-stringency screening using a rat PDE IV member B (r-PDE IVB) probe. Expression of the human (h) cDNA in Escherichia coli results in cAMP-specific PDE activity that is Rp sensitive. A single large open reading frame (ORF) predicts a 564-amino-acid protein with 92.9% identity to r-PDE IVB; at the nucleotide level the identity is 86.3%. This h-PDE IVB clone, HPB106, differs from a related cDNA clone isolated by others from h-monocytes [Livi et al., Mol. Cell. Biol. 10 (1990) 2678-2686]. Our analysis identifies the monocyte clone with r-PDE IVA. Southern blots using a 1.2-kb h-PDE IVB probe at low stringency suggest the presence of additional uncloned human PDE IV family members. Analysis of genomic Southern blots using short specific probes from the h-PDE IVA and h-PDE IVB cDNAs indicates that distinct genes encode these two PDE IV family members. RNA from fractionated normal human leukocytes shows major specific messages of 3.0 and 4.6 kb for h-PDE IVA and 3.7 kb for h-PDE IVB.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective action of 4'-azidothymidine triphosphate on reverse transcriptase of human immunodeficiency virus type 1 and human DNA polymerases alpha and beta

4'-Azidothymidine (ADRT) is a novel nucleoside analogue that exhibits potent inhibitory activity against the replication of human immunodeficiency virus (HIV) in lymphocytes. The mechanisms by which ADRT inhibits HIV reverse transcriptase (HIV-RT) as ADRT 5'-triphosphate (ADRT-TP), the active intracellular metabolite of ADRT, and as the ADRT-MP molecule incorporated into DNA were examined and compared to their effects on human DNA polymerases alpha and beta. Inhibition of HIV-RT by ADRT-TP is competitive against TTP and is more potent against RNA to DNA synthesis (Ki = 0.009 microM versus Km = 3.3 microM for TTP) than it is against DNA to DNA synthesis (Ki = 0.95 microM versus Km = 16.3 microM for TTP). ADRT-TP is also a more potent inhibitor for primer elongation on RNA template than on DNA template. ADRT-TP is a poor inhibitor of human DNA polymerases alpha (Ki = 62.5 microM) and beta (Ki = 150 microM) (Chen et al., 1992). The consequences of ADRT incorporation into DNA are strikingly different for the HIV-RT and for human DNA polymerases alpha and beta. DNA polymerases alpha and beta incorporate a single ADRT-MP molecule into nascent DNA at a very slow rate and continue to elongate. They are unable to incorporate a second consecutive ADRT-MP. However, HIV-RT is able to efficiently incorporate two consecutive ADRT molecules. Incorporation of two consecutive ADRT-MP molecules by HIV-RT prevents further DNA chain elongation. Incorporation of two ADRT-MP molecules separated by one deoxyribonucleoside monophosphate (dAMP, dCMP, or dGMP) also abolishes DNA chain elongation by HIV-RT.

[Compulsory sterilization and euthanasia--on the origins of a development that lead to the Fascist management of psychiatric patients]

When discussing and dealing with the way things went with German psychiatry during fascism the question arises constantly as to the scientific and theoretic self-interpretation of a specialist discipline that allowed itself to be misused without offering much resistance, if at all. The article makes an attempt to trace a few paths of specialist ideology at the turn of the 19th to the 20th century. The misuse of psychiatry and by psychiatry that has been practised both in the past and in the present cannot be understood if the guiding concepts of science generally ruling at the time are ignored.

Expression cloning of a rat B2 bradykinin receptor

A cDNA encoding a functional bradykinin receptor was isolated from a rat uterus library by a clonal selection strategy using Xenopus laevis oocytes to assay for expression of bradykinin responses. The predicted protein is homologous to the seven transmembrane G protein-coupled superfamily of receptors. Bradykinin and its analogs stimulate a Cl- current oocytes expressing the receptor with the rank order of potency: bradykinin approximately Lys-bradykinin greater than [Tyr8]-bradykinin much greater than [Phe6]bradykinin. This is the rank order of potency observed for these compounds in competitive binding assays on soluble receptor from rat uterus. Des-Arg9-bradykinin (10 microM) elicits no response when applied to oocytes expressing the receptor; thus, the cDNA encodes a B2 type bradykinin receptor. [Thi5,8,DPhe7]bradykinin, where Thi is beta-(2-thienyl)-alanine, is a very weak partial agonist and inhibits the bradykinin-mediated ion flux, suggesting the cDNA encodes a smooth muscle, rather than a neuronal, B2 receptor subtype. Receptor message has a distribution consistent with previous reports of bradykinin function and/or binding in several tissues and is found in rat uterus, vas deferens, kidney, lung, heart, ileum, testis, and brain. Receptor subtypes are a possibility because several tissues contain two or three message species (4.0, 5.7, and 6.5 kilobases). Southern blot high-stringency analysis demonstrated that the rat, guinea pig, and human genomes contain a single gene. As bradykinin is a key mediator of pain, knowledge of the primary structure of this receptor will allow a molecular understanding of the receptor and aid the design of antagonists for pain relief.

Determination of DNA binding specificities of mutated zinc finger domains

By substituting non conserved amino acids present in the postulated alpha-helical region of zinc finger domains, we demonstrated that Cys2/His2 type zinc finger domains could be targeted to new DNA binding sites. The putative alpha-helical region of the second SP1 zinc finger (RSDELQRH) was replaced by amino acids (KSSALISH) occurring in analogous zinc finger positions of human zinc finger protein Kox 29. The DNA binding specificity of the FPLC purified chimaeric protein (SP1-Kox 29) was determined by use of the target detection assay (TDA). Chimaeric protein SP1-Kox 29 was subjected to randomized oligonucleotides (GGG NNNN GGC) that were designed on the basis that each SP1 zinc finger interacts with 3-4 nucleotides concerning its cognate target site GGG GCGG GGC. By this analysis the DNA binding specificity of SP1-Kox 29 was shown to have switched from the cognate SP1 binding site to GGG GGTG GGC. Structure-function analysis of this type should facilitate the determination of DNA binding specificities for any individual zinc finger of interest.

Transition metals modulate DNA-protein interactions of SP1 zinc finger domains with its cognate target site

The metal free apoprotein of recombinant human transcription factor SP1 was used in metal reconstitution experiments to study the importance of zinc in facilitating DNA binding of zinc finger proteins. Our functional analysis indicates that several transition metals are capable of modulating DNA-protein interactions of zinc finger domains with their cognate DNA target sites. Excess or deficiency of divalent zinc, or the presence of transition metals, such as divalent cadmium, cobalt, copper, manganese and nickel impair DNA binding of zinc reconstituted SP1. In addition, functionally active SP1 protein can be obtained by metal reconstitutions in absence of zinc(II) by presence of cadmium(II)- and cobalt(II)-, to lesser extents by presence of nickel(II)- or manganese(II)chloride. This study indicates that zinc might play a functional role in regulating DNA protein interactions of zinc finger proteins in vivo. It is postulated that fluctuating divalent zinc alone or transition metals bound to cellular components might form mixed-ligand complexes that alter the zinc finger protein conformation and impair DNA binding.

Human beta nerve growth factor obtained from a baculovirus expression system has potent in vitro and in vivo neurotrophic activity

A baculovirus expression vector, which contains the coding sequences for human prepro (beta) nerve growth factor under control of the viral polyhedrin promoter, was constructed. Upon infection of insect cells with the recombinant virus, mature human beta nerve growth factor (rhNGF) was released into the culture fluid. The mature rhNGF was biologically active since rat pheochromocytoma (PC12) and human neuroblastoma (SH-SY5Y) cells were induced to extend neurites upon treatment with this material. This activity was abolished by treating with antiserum prepared against mature mouse beta NGF (mNGF). When compared with mNGF, rhNGF more rapidly elicited the differentiation response in both PC12 and SH-SY5Y cells. In an in vivo assay of cholinergic cell survival, rhNGF was nearly as potent as mNGF in protecting cholinergic neurons from degeneration following a fimbria-fornix lesion. These results show that the baculovirus expression system provides quantities of biologically potent human beta NGF suitable for a comprehensive program of research to ascertain beta NGF's potential as a therapeutic agent for the treatment of Alzheimer's disease.

Target Detection Assay (TDA): a versatile procedure to determine DNA binding sites as demonstrated on SP1 protein

We developed a rapid method designated Target Detection Assay (TDA) to determine DNA binding sites for putative DNA binding proteins. A purified, functionally active DNA binding protein and a pool of random double-stranded oligonucleotides harbouring PCR primer sites at each end are included the TDA cycle which consists of four separate steps: a DNA protein incubation step, a protein DNA complex separation step, a DNA elution step and a polymerase chain reaction (PCR) DNA amplification step. The stringency of selection can be increased in consecutive TDA cycles. Since tiny amounts of retained DNA can be rescued by PCR, buffer systems, salt concentrations and competitor DNA contents can be varied in order to determine high affinity binding sites for the protein of choice. To test the efficiency of the TDA procedure potential DNA binding sites were selected by the DNA binding protein SP1 from a pool of oligonucleotides with random nucleotides at 12 positions. Target sites selected by recombinant SP1 closely matched the SP1 consensus site. If DNA recognition sites have to be determined for known, mutated or putative DNA binding proteins, the Target Detection Assay (TDA) is a versatile and rapid technique for consideration.