Measurement and characterization of insulin-like growth factor binding protein-3 in human biological fluids: discrepancies between radioimmunoassay and ligand blotting

The inability to detect insulin-like growth factor binding protein-3 (IGFBP-3) in some circumstances by Western ligand blot analysis has emphasized the need to characterize IGFBPs by both ligand binding and immunological techniques. In this study, we have: 1) characterized and quantified IGFBP-3 in nonpregnancy, pregnancy, and fetal cord serum, follicular, peritoneal, and amniotic fluid, seminal plasma, cerebrospinal fluid (CSF), and urine; 2) established a new IGFBP-3 RIA that detects both intact and fragments of IGFBP-3; 3) identified both intact and fragments of IGFBP-3 by Western immunoblot techniques; and 4) addressed the discordance between Western ligand blot analysis and RIA by assessing fluids for IGFBP proteolytic activity. All fluids examined, except pregnancy serum, CSF, and amniotic fluid, displayed a 44-34-kilodalton (kDa) IGFBP-3 doublet by Western ligand blot analysis. Western immunoblot analysis using specific IGFBP-3 antiserum showed a 44-34-kDa IGFBP-3 doublet and a 28-kDa fragment in nonpregnancy serum, fetal cord serum, follicular fluid, and peritoneal fluid. The immunoreactive 42-38-kDa doublet was faint in urine and seminal plasma. IGFBPs in CSF did not cross-react with IGFBP-3 antiserum. Pregnancy serum and amniotic fluid contained only the 28-kDa fragment when compared against equal volumes of nonpregnancy serum. With the development of an IGFBP-3 RIA, IGFBP-3 could be accurately measured; urine, CSF, and seminal plasma contained the lowest levels of IGFBP-3 at 27 +/- 3 ng/ml (mean +/- SEM), 110 +/- 26 ng/ml, and 209 +/- 56 ng/ml, respectively. In increasing concentration: fetal cord serum contained 753 +/- 101 ng/ml; peritoneal fluid, 1124 +/- 130 ng/ml; follicular fluid, 2356 +/- 211 ng/ml; nonpregnancy serum, 3556 +/- 508 ng/ml; pregnancy serum, 3718 +/- 842 ng/ml; and amniotic fluid, 5150 +/- 688 ng/ml. The measurable concentrations of IGFBP-3 in CSF and the high concentrations measured in pregnancy serum and amniotic fluid conflicted with Western blot analysis. Thus, fluids were assessed for IGFBP proteolytic activity by incubation with a source of IGFBP-3, either nonpregnancy serum or purified IGFBP-3. All fluids displayed some proteolytic activity with either assay. Fluids with little protease activity (nonpregnancy serum, follicular fluid, and urine) showed a close relationship between immunoassayable IGFBP-3 by RIA and IGFBP-3 band intensity by Western ligand blot. Fluids with high proteolytic activity (pregnancy serum, CSF, seminal plasma, peritoneal fluid, and amniotic fluid) gave discrepant IGFBP-3 values between RIA and Western ligand blot.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of the high molecular weight insulin-like growth factor complex in term pregnancy serum

Insulin-like growth factors (IGFs) circulate in human adult serum predominantly as a high mol wt complex of 150 kilodaltons (kDa), which is made up of three subunits: alpha, the acid-labile subunit, a glycoprotein of around 85-100 kDa; beta, the acid-stable IGF-binding protein subunit, which is the 40-kDa GH-dependent glycoprotein IGF-binding protein-3 (IGFBP-3); and gamma, the 7.5 IGF-I or -II peptide subunit. During human pregnancy, all three subunits are elevated when measured by RIA. However, recent ligand blotting studies have shown that IGFBP-3 is markedly reduced during pregnancy. When pregnancy serum is acidified and neutralized to inactivate endogenous alpha-subunit, ternary complex formation is normal with exogenous radiolabeled alpha-subunit, indicating functional IGFBP-3. We have attempted to clarify the status of IGFBP-3 and the high mol wt (alpha beta gamma) complex in human term pregnancy serum by further analyses. Term pregnancy (TP) or nonpregnancy (NP) pooled sera were fractionated on a S-300 neutral column. The high mol wt (125-150 kDa) and the low mol wt (30-40 kDa) IGF-IGFBP complexes were identified by both RIA for IGFBP-3 and ligand blotting; each was pooled separately. Half of each pool was lyophilized and rechromatographed in acid to separate the IGF-I peptides from their IGFBPs. The IGFBP fractions were recovered for further studies. When the IGFBPs from the high mol wt complex were cross-linked to [125I]IGF-I or -II, bands of 48, 34, 26, and 21 kDa, which were more intense with [125I]IGF-II, were observed, and all were immunoprecipitable by anti-IGFBP-3 antibody. The smaller forms were elevated in TP serum. Affinity cross-linking analysis with [125I]alpha-subunit showed that the IGFBPs from the high mol wt, but not the low mol wt, complex can reform the ternary 150-kDa complex when cold IGF-I or IGF-II is added exogenously. A smaller 130-kDa complex was also present, and it was the predominant form in TP serum. Both bands were immunoprecipitable by anti-IGFBP-3 antibody. When purified alpha-subunit or fractions from neutral Sephacryl S-300 chromatography were cross-linked to covalent [125I]IGF-II:IGFBP-3, a specific band at 150 kDa was observed with pure alpha-subunit as well as with S-300 150- to 100-kDa serum fractions. These results suggest that 1) functional alpha-subunit is present in TP serum; 2) intact as well as smaller fragments of IGFBP-3 are present in the big complex of TP serum and are able to bind IGF and complex with alpha-subunit; and 3) IGFBP-3 in TP serum has reduced binding to [125I]IGF-I, but not to [125I]IGF-II.

Acanthamoeba castellanii RNA polymerase II transcription in vitro: accurate initiation at the adenovirus major late promoter

We have developed and characterized an efficient in vitro system from the protozoan, Acanthamoeba castellanii, that accurately initiates transcription from the adenovirus-2 major late promoter (AdMLP). Transcription by A. castellanii RNA polymerase II (pol II) is initiated at the same nucleotide (nt) that is used by HeLa extracts and is dependent upon adenovirus sequences located between nt -51 and the region around the transcription start point (tsp). The results suggest that the A. castellanii transcription factors for pol II which determine the tsp and the promoter elements that they recognize have been functionally conserved during evolution.

Isolation of genomic DNA encoding transcription factor TFIID from Acanthamoeba castellanii: characterization of the promoter

We have isolated a genomic clone encoding Acanthamoeba castellanii TFIID. The clone contains the entire TFIID gene, 300 bp of 5' promoter sequences and several hundred base pairs of 3' non-coding sequence. The coding region is interrupted by two short introns, but is otherwise identical to Acanthamoeba TFIID cDNA. Comparisons between forty four Acanthamoeba intron 5' and 3' boundaries suggest a 5' splice site consensus of GTACG(T/C) and a 3' consensus of CAG. We determined the position of the transcription initiation site used in vivo, and show that the same site is used in vitro by homologous nuclear extracts. Deletion analysis of the promoter region shows that the minimal promoter required for efficient expression in vitro is located between -97 and +4 relative to the transcription start site. Three regions within the promoter are important for transcription in vitro; sequences between -97 and -35, the TATAAA box and the initiation region. The initiation region is dispensable but appears to position the transcription start site relative to the TATAAA box. The TATAAA box is absolutely required for transcription initiation whereas the upstream region stimulates transcription approximately five-fold.

[Experimental studies of lung lesions in rabbits caused by Streptomyces thermohygroscopicus]

Imitating the natural way of infection of Farmer's lung disease, we succeeded in inducing acute lesions of Farmer's lung disease in rabbits by the dry powder of thermohygroscopicus. Histopathological examination revealed typical interstitial pneumonitis, alveolitis and bronchiolitis. One week after the inhalation of the dry powder of thermohygroscopicus, the precipitins could be detected in the rabbits' serum by immunoblotting. Depending on the lung lesions of rabbits, we discussed the pathogenetic mechanisms of Farmer's Lung.

Cloning and expression of the Acanthamoeba castellanii gene encoding transcription factor TFIID

We have cloned and characterized the cDNA encoding transcription factor TFIID from the eukaryote, Acanthamoeba castellanii. The gene occurs as a single species, encodes one mRNA and, presumably, a single protein. A. castellanii TFIID contains two recognizable domains, a nonconserved N-terminal domain and a highly conserved C-terminal domain. Similarities between the amino acid (aa) sequences of TFIID from several organisms are also found within the N-terminal 78 aa, suggesting a potential role in TFIID function. Full-length or truncated A. castellanii TFIID produced in Escherichia coli binds to a TATA box and is able to activate transcription in a TFIID-depleted HeLa cell extract, but the C-terminal 180-aa domain was found to be less efficient in these reactions.

Failure of pulmonary acidosis to increase respiratory drive

Experiments were performed to determine whether increases in acidity isolated to the pulmonary circulation would stimulate hypothesized pulmonary chemoreceptors and increase respiratory drive in the anesthetized paralyzed mechanically ventilated cat (n = 9). Respiratory drive was assessed by measuring the frequency and amplitude of the integrated phrenic neurogram. To create an isolated pulmonary acidosis, blood returning to the lung was acidified by infusion of 0.3 M lactic acid (1.91 ml/min) into the inferior vena cava, while systemic arterial pH was restored to near normal levels by simultaneous infusion of base (0.3 M NaOH) into the left atrium. Six minutes after the start of this dual infusion of acid and base, right ventricular (pulmonary) pH decreased from 7.286 to 7.179 and PCO2 increased 7 Torr. Systemic arterial pH and PCO2 were unchanged from measurements immediately before the infusion. This level of pulmonary acidosis failed to increase respiratory drive as assessed by phrenic activity. To test the sensitivity of the preparation to known systemic arterial chemical stimuli, a combined pulmonary and systemic acidosis was elicited by infusion of 0.3 M lactic acid into the inferior vena cava and 0.3 M NaCl into the left atrium. This infusion significantly lowered both systemic arterial and pulmonary arterial pH (7.343 to 7.155 for systemic arterial pH and 7.286 to 7.067 for pulmonary pH) and increased phrenic efferent activity 45%. We conclude that phrenic efferent activity is unaffected by moderate reductions in the pH of the pulmonary circulation in the absence of a significant systemic arterial acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Retinoblastoma gene product activates expression of the human TGF-beta 2 gene through transcription factor ATF-2

The retinoblastoma susceptibility gene product (pRb) plays an important role in constraining cellular proliferation and in regulating the cell cycle. The pRb inhibits transcription of genes involved in growth control (reviewed in ref. 3) and can regulate transforming growth factor beta 1 (TGF-beta 1) gene expression. TGF-beta isoforms also down-regulate cellular proliferation. To determine whether pRb also regulates expression of other TGF-beta isoforms, we examined the effect of pRb on the expression of the human TGF-beta 2 gene. The human TGF-beta 2 promoter contains multiple elements including an ATF site, which is essential for basal promoter activity. Here we report that pRb activates transcription of the human TGF-beta 2 gene. The promoter element responsible for pRb-mediated transcriptional regulation is a binding site for ATF proteins, an extensive transcription factor family. We provide evidence that implicates ATF-2 in pRb-responsiveness. First, the ATF promoter element in the TGF-beta 2 gene is a high-affinity ATF-2-binding site. Second, a GAL4-ATF2 fusion protein can support pRb-mediated transcriptional activation of a promoter containing GAL4-binding sites. Third, ATF-2 in nuclear extracts can interact with pRb. Our results reveal a new mechanism by which pRb constrains cellular proliferation: by activating expression of the inhibitory growth factor, TGF-beta 2.

Effect of pretreatment with epoxy compounds on the mechanical properties of bovine pericardial bioprosthetic materials

Early failures of bovine pericardial heart valves are due to leaflet perforation, tearing and calcification. Since glutaraldehyde fixation has been shown to produce marked changes in leaflet mechanics and has been linked to development of calcification, bovine pericardium fixed with the four hydrophilic epoxy formulations and their mechanical properties are studied in this paper. We measured the thicknesses, shrinkage temperatures, stress relaxations and stress-strain curves of bovine pericardiums after different treatments with (1) non-treatment (fresh), (2) glutaraldehyde (GA), (3) epoxy compounds followed by the posttreatment with GA (EP 1#, EP 2#), and (4) epoxy compounds (EP 3# and EP 4#). Results of this study showed that the hydrophilic epoxy compounds are good crosslinking agents. There are no significant differences of shrinkage temperature and ultimate tensile stress among all tissue samples pretreated with GA, EP 1# and EP 2#. However, the stress relaxations of tissue-samples pretreated with epoxy compounds followed by the posttreatment with GA (EP 1# and EP 2#) are significantly slower than that pretreated with GA, and the strains at fracture of EP 1# and EP 2# are also significantly larger than that of GA or epoxy compounds. These facts show that the bovine pericardium pretreated with the epoxy compound followed by the posttreatment with GA (EP 1# and EP 2#) possesses greater tenacity and potential durability in dynamic stress.

Effect of capsaicin and resiniferatoxin on peptidergic neurons in cultured dorsal root ganglion

The neurotoxic effect of capsaicin has been shown to be selective on a subpopulation of small dorsal root ganglion neurons in newborn animals. The aim of this study was to provide evidence of the long lasting effect of capsaicin and its ultrapotent analog resiniferatoxin (RTX) on sensory peptidergic neurons maintained in organotypic cultures. The effects of the two irritants were examined on neurons that contained substance P (SP) and calcitonin gene-related peptide (CGRP). Exposure of the cultures to 10 microM capsaicin and 100 nM RTX for periods of 2 days or longer resulted in almost complete elimination of SP-immunoreactive (IR) neurites and reduction, but not elimination, of CGRP-IR neurites. In addition, both 10 microM capsaicin and 100 nM RTX significantly reduced the number of SP- and CGRP-IR cell bodies within DRG explants. Capsaicin in 100 microM concentration produced complete elimination of SP-IR fibers and a greater decrease in the number of CGRP-IR fibers, but failed to completely eliminate IR cell bodies. Exposure of the cultures to the irritants in the same concentrations for 90 min did not produce a measurable effect on SP- or CGRP-IR in neurites or cell bodies. It is important to establish that the effect of capsaicin and RTX on cultured neurons was of long duration (longer than 4 days) and is therefore different from depletion of peptides. These findings demonstrate that processes of cultured sensory neurons are much more sensitive to capsaicin and RTX than cell bodies. Furthermore, our results show that SP-IR neuronal elements are more sensitive to capsaicin than CGRP-IR elements. These data suggest that cultured sensory neurons express the functional properties of differentiated sensory neurons in vivo.

[Quality of dihuang (Rehmannia spp.)]

In this paper, the contents of catalpol, water-extract and alcohol-extract materials, ash, total reducing sugar and inorganic elements in Dihuang from different habitats have been measured. The result shows that Huai Dihuang, the genuine drug, excels all those from other habitats in quality. The quality of commercial dry Dihuang may be related closely to the production area, storage time, etc.

Thromboxane A2 mimetic, U46,619, and slowly adapting stretch receptor activity in the rabbit

The effect of infusing the thromboxane A2 mimetic U46,619 on afferent activity from slowly adapting airway stretch receptors (SARs) in the anesthetized rabbit was examined in these experiments. SAR vagal afferent fibers (n = 29) were identified by their slow adaptation to a sustained (10-15 s duration) lung inflation in the closed-chest, mechanically ventilated animal (n = 16). Intravenous infusion of U46,619 increased the discharge frequency of the SAR, measured at the end of inspiration, in a dose-dependent manner: by 6.6% and 8.0% at doses of 0.1 and 0.5 microgram of U46,619/kg, respectively. This increase in SAR activity was correlated with increases in end-inspiratory tracheal airway pressure (6.4% at 0.1 micrograms/kg and 9.1% at 0.5 micrograms/kg). Higher doses of U46,619 could not be administered due to decreases in systemic arterial blood pressure. The increase in SAR activity and tracheal airway pressure was qualitatively comparable to the response to histamine (25 micrograms/kg), a known bronchoconstrictor. We conclude that intravenous infusion of U46,619 in the anesthetized rabbit at doses that elicit significant hemodynamic effects causes modest bronchoconstriction and comparable increases (less than 10%) in SAR afferent nerve activity. From these data, it appears that U46,619 has no direct effect on SARs, but rather increases SAR activity due to bronchoconstriction.

Differentiation of multiple domains in the herpes simplex virus 1 protease encoded by the UL26 gene

Previous studies have shown that the herpes simplex virus 1 gene UL26 encodes a 635-amino acid protease that cleaves approximately 20 amino acids from the carboxyl terminus of itself and of a 329-amino acid product of the UL26.5 gene. The results of studies with a variety of protease inhibitors showed that the UL26 protease was inhibited by serine protease inhibitors but not by inhibitors of cysteine protease, aspartic acid protease, or metalloprotease. Mutations resulting in amino acid substitutions, deletions, or insertion of stop codons in the gene or of 20-amino acid stretches into the protease have delineated the dispensable domains I and IV at the amino and carboxyl domains of the gene product. The essential carboxyl-proximal domain (III) can be separated from the essential amino-proximal domain (II) by at least 20 amino acids. The amino-proximal domain is the most conserved region among varicella-zoster virus and human cytomegalovirus homologues of UL26. Of the conserved aspartic acid, histidine, or serine amino acids in this domain, only histidine-61 and -148 could not be replaced without impairment of the proteolytic activity.

Site-directed mutagenesis of the phosphate-binding consensus sequence in Escherichia coli adenylosuccinate synthetase

Adenylosuccinate synthetases from different sources contain an N-terminal glycine-rich sequence GDEGKGK, which is homologous to the conserved sequence GXXXXGK found in many other guanine nucleotide-binding proteins or enzymes. To determine the role of this sequence in the structure and function of Escherichia coli adenylosuccinate synthetase, site-directed mutagenesis was performed to generate five mutant enzymes: G12V (Gly12----Val), G15V (Gly15----Val), G17V (Gly17----Val), K18R (Lys18----Arg), and I19T (Ile19----Thr). Comparison of the kinetic properties of the wild-type enzyme and those of the mutant enzymes revealed that the sequence is critical for enzyme activity. Replacement of Gly12, Gly15, or Gly17 with Val, or replacement of Lys18 with Arg, resulted in significant decreases in the kcat/Km values of the enzyme. Because the consensus sequence GXXXXGK(T/S) has been found in many GTP-binding proteins, isoleucine at position 19 in the E. coli adenylosuccinate synthetase was changed to threonine to produce the sequence GDEGKGKT. This mutation, which more closely resembles the consensus sequence, resulted in a 160-fold increase in the Km value for substrate GTP; however, there were no great changes for the other two substrates, IMP and aspartate. Based on these data, we suggest that the N-terminal glycinerich sequence in E. coli adenylosuccinate synthetase plays a more important role in enzyme catalysis than in substrate binding. In addition, a hydrophobic amino acid residue such as isoleucine, leucine, or valine, rather than threonine, may play a critical role in GTP binding in adenosuccinate synthetase. These findings suggest that the glycine-rich sequence in adenylosuccinate synthetase functions differently relative to those in other GTP binding proteins or enzymes.

Molecular analysis of Xenopus laevis SPARC (Secreted Protein, Acidic, Rich in Cysteine). A highly conserved acidic calcium-binding extracellular-matrix protein

SPARC (Secreted Protein, Acidic, Rich in Cysteine) is expressed as a 1.6 kb mRNA in Xenopus laevis. On the basis of cDNA sequence analysis, Xenopus SPARC has a core Mr of 32643, with one potential N-glycosylation site. Western analysis of SPARC isolated from Xenopus long bone indicates that the mature protein has an Mr of 43,000. At the amino acid level, Xenopus SPARC has 78-79% sequence similarity to mouse, bovine and human SPARC. The least-conserved region is found within the N-terminal glutamic acid-rich domain, with the C-terminal Ca(2+)-binding domain being the most conserved. Adult Xenopus tissues show the same pattern of tissue-specific distribution of SPARC mRNAs as adult mouse.

[Suppressive effects of safflower yellow on immune functions]

Safflower yellow (SY) extracted from Carthamus tinctorius L contained chalconoid compounds, 75% of which was safflomin A. SY ip 50-450 mg.kg-1.d-1 x 6-8 d in mice decreased serum lysozyme concentration and phagocytosing functions of both peritoneal macrophages and peripheral leukocytes; diminished the production of plaque forming cells, specific rosette forming cells, and antibody; inhibited delayed type hypersensitivity reaction and the activation of T suppressor cells elicited by supraoptimal immunization. Experiments in vitro showed inhibitory effects on [3H]TdR incorporation during human peripheral T- and B-lymphocyte proliferation by SY 0.03-3.0, 0.1-2.0 mg.ml-1 respectively, murine mixed lymphocyte culture response and the production of interleukin-2 by SY 0.1-2.5 mg.ml-1. In conclusion, SY produced declines in both nonspecific and specific immune functions.

[Assessment of induced noninvasively postextrasystolic potentiation on the right ventricular function in patients with cor pulmonale]

The indices of postextrasystolic potentiation degree (Rpesp: Rcdz/dt, RHI, delta Q-Zc, delta PEP/RVET) were observed in the patients with cor-pulmonale, chronic obstructive pulmonary disease (COPD) and normal subjects using extrasystole induced by transesophageal atrial pacing combined with differential impedance rheopneumography. The results shows that Rpesp of the patients with cor-pulmonale was larger than that of the patients with COPD and the normal subjects. The positive rates of RCdz/dt, RHI, delta Q-Zc, delta PEP/RVET was detected respectively in 95%, 100%, 85%, 85% of the cor-pulmonale and in 60%, 60%, 70%, 60% in COPD. It suggested that this method be a safe, simple and reliable one to assess right ventricular contraction function and to diagnose early cor-pulmonale.

[Sedative chemical constituents of leaves of Apocynum venetum Linn]

Eight constituents were isolated from the ether solvent fraction of leaves of Apocynum venetum and identified as triacontanol, beta-sitosterol, quercetin, hyperin, long-chain fatty acids (C28-C34), lupeol, scopoletin and isofraxidin. Isofraxidin and hyperin were effective sedative components.

[Effects of Epimedium sagittatum Maxim. Polysaccharides on DNA synthesis of bone marrow cells of "yang deficiency" animal model caused by hydroxyurea]

A study was made on the effects of Epimedium sagittatum polysaccharides on DNA synthesis of bone marrow cells of "yang deficiency" animal model caused by hydroxyurea with methods of cell culture in vitro and determination of 3H-TdR incorporating DNA of bone marrow cells. The results showed that after the treatment with 100 micrograms of Epimedium sagittatum polysaccharides, the cell multiplication rate was increased by 72% and DNA synthesis rate increased by 68%, in 1 x 10(6) cells.

[Chemical constituents of Ipomola batatas Lam]

Three chemical compounds isolated from the leaves and stems of Ipomoea batatas were identified as fumaric acid, succinic acid and 7,3',4'-trimethylquercetin by chemical and spectroscopic analysis. In this paper, an analysis of the amino-acids of Ipomoea batatas is also reported.