High-level expression and simple purification of recombinant human insulin-like growth factor I

Human insulin-like growth factor I (IGF-I) was expressed in Escherichia coli as a truncated beta-galactosidase-IGF-I fusion protein. The Lac Z" gene was truncated by removal of a 490 bp fragment which encoded 163 N-terminal residues of beta-galactosidase and was connected to the IGF-I cDNA by a linker encoding hydroxylamine cleavage recognition sequence. By truncating Lac Z" gene, the overall yield and purification procedures of IGF-I from fusion protein have been improved. The fusion protein was produced in the form of insoluble inclusion bodies with isopropyl-1-thio-beta-D-galactoside (IPTG) induction. After cleavage of the fusion protein with hydroxylamine, the released IGF-I was purified to homogeneity by a cation exchange chromatography, refolding and reverse-phase high performance liquid chromatography (rp-HPLC). The purified IGF-I was found to be indistinguishable from the native IGF-I by N-terminal amino acid sequence, SDS-polyacrylamide gel electrophoresis, and rp-HPLC and by biological activities such as thymidine uptake, protein synthesis and receptor binding. These results suggest that the expression and simple purification of recombinant human IGF-I described in this paper may be useful for large scale production of IGF-I.

Novel pre-C/C gene mutants of hepatitis B virus in chronic active hepatitis: naturally occurring escape mutants

We have analysed serum samples taken from hepatitis B virus (HBV) e antigen (HBeAg)-positive and HBeAg-negative chronic active hepatitis (CAH) patients by PCR using primers spanning the pre-core/core (C) and pre-S1/S2 ORFs. Nucleotide sequence analysis showed that among 18 HBV-infected CAH patients, 11 had virus with a G to A mutation (nucleotide 1896; leading to the formation of a stop codon) and one patient also had virus with an additional G to A mutation three nucleotides downstream (nucleotide 1899). HBV from three patients that were HBeAg-negative showed a 1 bp deletion at nucleotide 1937, causing pre-termination of the C gene. Mutation frequencies in the sequences identified as coding for cytotoxic T lymphocyte epitopes, B cell epitopes, CD4+ helper T cell epitopes and arginine-rich regions of the HBV C peptide were investigated. Mutations were more frequently identified in these regions, suggesting that the mutations might have been selected as a result of immune responses.

Overexpression and purification of human immunodeficiency virus type 1 env derived epitopes in Escherichia coli

In order to develop a reliable and inexpensive serodiagnostic method, a part of envelope gene of HIV-1, gp120' and gp41' (HIV-1 env a.a. 295-474 and a.a. 556-647) was cloned into a T7 expression vector (pET3d). The fusion protein (gp120'-gp41') was overexpressed in Escherichia coli, then purified to homogeneity by a simple gel filtration chromatography. Western blot analysis and enzyme-linked immunosorbent assay (ELISA) using the purified fusion protein showed a high sensitivity and a specificity for the detection of anti HIV-1 antibodies in testing human plasma. These results suggest that the expression scheme employing a direct expression vector and the rapid purification method are reliable and applicable for obtaining a large quantity of HIV-1 env protein for diagnoses of HIV-1 infections.

Transcriptional repression of human insulin-like growth factor-II P4 promoter by Wilms' tumor suppressor WT1

The Wilms' tumor suppressor gene wt1 encodes a zinc finger-containing protein that binds to the same DNA sequence as Egr-1, a mitogen-inducible immediate-early gene product that activates transcription. In this study, we investigated whether the human insulin-like growth factor-II (IGF-II) P4 promoter might be a target for transcriptional repression mediated by WT1. Using constructs of the IGF-II P4 promoter linked to the chloramphenicol acetyltransferase gene, we have demonstrated that the WT1 protein represses expression of the IGF-II gene through a GCGGGGGAG response element spanning nucleotides -87 to -65 of the IGF-II P4 promoter. Conversely, we have shown that the Egr-1 activates transcription of the IGF-II gene through the same response element. WT1 and Egr-1 proteins interact directly with the WT1/Egr-1 response element of the IGF-II promoter 4 in gel mobility-shift assays. These findings demonstrate the importance of the WT1/Egr-1 consensus element for the expression of the IGF-II gene in response to positive or negative transcription signals.

Regulation of transforming growth factor-beta 1 expression by the hepatitis B virus (HBV) X transactivator. Role in HBV pathogenesis

TGF-beta 1 has been implicated in the pathogenesis of liver disease. The high frequency of detection of the hepatitis B virus X (HBx) antigen in liver cells from patients with chronic hepatitis, cirrhosis, and liver cancer suggested that expression of HBx and TGF-beta 1 may be associated. To test this possibility, we examined the expression of TGF-beta 1 in the liver of transgenic mice expressing the HBx gene. We show that the patterns of expression of TGF-beta 1 and Hbx protein are similar in these mice and that HBx activates transcription of the TGF-beta 1 gene in transfected hepatoma cells. The cis-acting element within the TGF-beta 1 gene that is responsive to regulation by Hbx is the binding site for the Egr family of transcription factors. We further show that the Egr-1 protein associates with the HBx protein, allowing HBx to participate in the transcriptional regulation of immediate-early genes. Our results suggest that expression of Hbx might induce expression of TGF-beta 1 in the early stages of infection and raise the possibility that TGF-beta 1 may play a role in hepatitis B virus pathogenesis.

Gradual accumulation of mutations in precore core region of HBV in patients with chronic active hepatitis: implications of clustering changes in a small region of the HBV core region

The sequence in the precore and core region of the hepatitis B virus (HBV) genome in the serum of five chronic active hepatitis patients at four different stages in each individual were studied by polymerase chain reaction and DNA sequencing to determine the prevalence and type of precore and core mutants in each chronic active hepatitis (CAH) patient. Gradual changes of the virus genome in each CAH patient in precore and core regions were identified. Except for the virus from one patient, the mutant viruses showed gradual changes of genome sequences, which resulted in the generation of stop codons at the precore and core region, causing the association of active hepatitis in each patient even in the presence of anti-HBe. Mutational hot spots in the core region, which includes a clustering of changes in a small region of 14 amino acids (codons 84-97 from the start of the core gene) were found in all patients. This region of mutational hot spots in the core might be a major target of cytotoxic T lymphocytes (CTL), which has evolved under the pressure of immune selections, and these mutants might play a important role in the pathogenesis of viral hepatitis.

Age related change in the vasoactive intestinal polypeptide-immunoreactive neurons in the cerebral cortex of aged rats

Recent studies have explored certain changes in neurons containing neuropeptides with aging. However, until now, the degree of vasoactive intestinal polypeptide (VIP)-containing neuronal cell loss in the aged CNS has not yet been established with certainty, and available data are often contradictory. Changes in the VIP-containing neurons with aging were demonstrated by immunocytochemisty. Major loss of VIP-immunoreactive neurons in the aged rat brain were observed in frontal cortex area 3, parietal cortex area 1, hindlimb area, temporal cortex area 1 and 2, monocular part of occipital cortex area 1, occipital cortex area 2, and retrosplenial cortex. Frontal cortex area 1 and 2, parietal cortex area 2, forelimb area, binocular part of the occipital cortex area 1, and the dentate gyrus were moderately decreased. The axis of the VIP neurons in the aged group showed an irregular orientation tendency, especially in layers II and III. These results indicate the involvement of a neuronal system containing VIP in the aging brain, and provide the first morphological evidence for the loss of VIP neurons in the cerebral cortex of the aged rat.

Overexpression and simple purification of human immunodeficiency virus-1 gag epitope derived from a recombinant antigen in E. coli and its use in ELISA

To develop a test for diagnosis of human immunodeficiency virus-1 (HIV-1) exposure sensitivity, a part of the gag gene was cloned and expressed in Escherichia coli, using expression vectors containing a trp promoter. The immunoreactivity of recombinant protein was determined using HIV-1 specific antibodies in a Western blot analysis. The recombinant plasmid, pYHCgag3, gag gene was fused to the trpE' gene linked to the hydroxylamine (HA) cleavage recognition sequence which was induced to overexpress a core antigen (gag a.a. 121-398 from plasmid BH10) as fusion protein in the form of insoluble inclusion body. Recombinant gag was purified by a simple single step purification procedure. After partial purification of inclusion bodies and subject to the HA-cleavage treatment, gag protein was further purified to homogeneity using DEAE-Sepharose chromatography. The purified core antigen offered reliable results with high sensitivity and specificity for identification of HIV-1 antibodies when tested in the enzyme-linked immunosorbent assay (ELISA). These results suggest that mass production of recombinant core antigen will provide a valuable resource to HIV-1 serodiagnostics for the screening of large groups of blood donors to prevent HIV-1 infection.

Inhibition of protein phosphatases activates P4 promoter of the human insulin-like growth factor II gene through the specific promoter element

To understand the transcriptional regulation of the human insulin-like growth factor II (IGF-II) gene, we examined the effects of okadaic acid, a potent in vitro inhibitor of protein phosphatases, on the activation of human IGF-II gene expression. Treatment of A-549 human lung adenocarcinoma cells with okadaic acid increased expression of the IGF-II mRNAs. Since the 4.8-kb mRNA is transcribed under the control of human IGF-II P4 promoter, we examined the P4 promoter element responsible for the okadaic acid-mediated transcriptional activation. Transfection of IGF-II P4 promoter-chloramphenicol acetyltransferase constructs demonstrated that the effects of okadaic acid on the induction of IGF-II gene expression are mediated through multiple promoter elements, including an Egr-1 consensus element. We have also shown that okadaic acid induced the expression of the transcription factor Egr-1. Moreover, by using a GAL4-Egr-1 fusion protein, we have directly demonstrated that okadaic acid positively regulates Egr-1 transcriptional activity in vivo. These results indicate that protein phosphatases play an important role in the transcriptional regulation of the IGF-II.

Functional analysis of hepatitis B virus transactivator X: implication of the leucine zipper-like region and C-terminal seven conserved amino acids in functional regions

X protein of hepatitis B virus (HBV-X) is a transactivator to a wide variety of viral and cellular transcriptional regulatory elements. Since HBV-X does not act on a common cis-regulatory element of a wide variety of regulatory elements nor does it bind to DNA directly, it has been proposed that HBV-X acts indirectly through protein-protein interactions with other transcription factors or signal transducing pathway. In order to determine the functional domain of HBV-X, we have constructed and analyzed a number of deletion and site specific mutants. Our results showed that leucine zipper-like sequences were found in the C-terminal region of HBV-X and were very important for its transactivating activity. In the analysis of deletion mutants, seven conserved and strong basic amino acids (amino acids 135-141) were essential for the transactivating activity of HBV-X.

Genomic typing of hepatitis C viruses from Korean patients: implications of genome variation in the E2/NS1 region

Comparative nucleotide sequence studies of a 2.4-kb cDNA fragment (nt -49 to 2361) of Korean-type hepatitis C virus (HCV) were carried out. The nt sequences of the Korean HCV isolates have stronger sequence homologies with type II HCV (Japanese HCV-BK) than with types I (HCV-1) or III (HCV-6). In addition, the net sequences of a part of the core region of ten different samples confirmed that prevalent HCV in Korea belongs to type II with the exception of one sample which belongs to type III. The nt sequence of a cDNA fragment of E2/NS1 region of HCV, from six different serum samples, which comprises the hypervariable regions-1 (HVR-1) and -2 (HVR-2), revealed sequence heterogeneity with type II HCV (75.4 to 80.7% nt homology and 75.5 to 79.7% amino acid homology). However, it was relatively well conserved among the Korean isolates, in fact, aa sequences of HVR-2 as well as HVR-1, converged into two groups. Also we found consensus sequences (T.V.G..AGRTT.G..SLE......K) in HVR-1. Thus, we propose that the conserved patterns in HVR-1 and -2 are characteristics of the six different Korean isolates.

Characterization of the P4 promoter region of the human insulin-like growth factor II gene

The human insulin-like growth factor II (IGF-II) gene contains four promoters (P1, P2, P3 and P4). In order to determine the mechanism by which the P4 promoter is controlled, the human IGF-II P4 promoter was analyzed in cell lines. DNA sequence analysis of the human IGF-II P4 promoter gene showed that the P4 promoter region contains a TATA-like sequence and several G+C rich regions which are essential for transcription. Analysis of the transcription initiation site by S1 nuclease mapping revealed two transcription start sites; both are located immediately behind TATA-like sequence. To determine the location of sites that may be important for the function of the human IGF-II P4 promoter, we constructed chimeric genes of the human IGF-II P4 promoter fused to the coding region for chloramphenicol acetyltransferase (CAT). These constructs were transfected into HepG2, PLC/PRF/5, G401 and A549 cells, and were examined for CAT activity. All transfected cells showed a similar profile of CAT activity. Sequences responsible for putative enhancer and silencer regions were identified and the 5' flanking sequences of the human IGF-II P4 promoter contain negative regulatory regions (-213 to -174). The 53-base pair fragment located between 111 and 59 base pairs upstream of the start site contains positive regulatory activity. Gel mobility shift assay showed that Sp1 and another proteins might be involved in positive regulation of the human IGF-II P4 promoter.

Treatment failure in malignant gestational trophoblastic disease

One hundred and thirty-three patients with malignant gestational trophoblastic disease (GTD) were admitted. All patients (86/86) of the nonmetastatic and metastatic low-risk groups and 89.4% (42/47) of the metastatic high-risk group showed remission. The overall remission rate was 96.2%. Among 5 patients with brain metastases, however, only one (20%) survived. We arrived at two main conclusions. First, brain metastatic lesions did not successfully respond to therapy utilizing conventional chemotherapeutic regimens. Second, the key factors for successful outcome in brain metastases were early diagnosis and aggressive initial therapy. Therefore, early detection of brain metastases should be made with: (1) fine computerized tomography (CT) or magnetic resonance imaging (MRI), (2) measurement of the ratio of serum to cerebrospinal fluid hCG concentration, and (3) early recognition of their clinical features.

Rapid and simple purification of human immunodeficiency virus 1 epitope gp41

In order to develop a reliable and inexpensive serodiagnostic method, part of the transmembrane glycoprotein gene of HIV-1, gp41', (HIV-env 548-646) was cloned into an expression vector, pCT10 with a sequence encoding a hydroxylamine cleavage site and with a part of Lac Z gene (Lac 2": 834 base pairs) as a fusion partner. Overexpression of Lac Z"-gp41' was induced in E. coli and the gp41' fusion protein was purified to homogeneity by centrifugation, hydroxylamine cleavage and an ion-exchange chromatography. Western blot analysis and enzyme-linked immunosorbant assay (ELISA) using the purified gp41 fragment showed high sensitivity and specificity of gp41 as an antigen to detect anti HIV-1 antibodies in testing human sera. These results suggest that this simple and rapid purification method is reliable for obtaining a large quantity of purified gp41'.

Detection of extrapulmonary tuberculosis with gallium-67 scan and computed tomography

We evaluated 23 patients with extrapulmonary tuberculosis (TB) with 67Ga imaging to assess its usefulness in the diagnosis of this condition. We performed computed tomography (CT) in 17 patients to assess CT features of extrapulmonary TB in comparison with findings from 67Ga scans. Nineteen of 23 patients (83%) had positive findings on 67Ga scans. One of five patients with tuberculous mediastinal lymphadenopathy, two patients with cervical lymphadenitis and a patient with renal TB had negative 67Ga scans. It was observed that the detection of previously unrecognized primary foci of TB, without concomitant pulmonary TB, was possible using 67Ga imaging in five patients (22%). The 67Ga scan was relatively sensitive for the localization of extrapulmonary TB. It is suggested that the 67Ga scan could serve as a screening method, when followed by CT and ultrasonography, for the initial detection of occult tuberculous lesions, especially in patients with prolonged fever.

The retinoblastoma gene product regulates Sp1-mediated transcription

We have demonstrated that the retinoblastoma gene product (Rb) can positively regulate transcription from the fourth promoter of the insulinlike growth factor II gene. Two copies of a motif (the retinoblastoma control element) similar to that found in the human c-fos, transforming growth factor beta 1, and c-myc promoters are responsible for conferring Rb regulation to the fourth promoter of the insulinlike growth factor II gene. We have shown that the transcription factor Sp1 can bind to and stimulate transcription from the retinoblastoma control element motif. Moreover, by using a GAL4-Sp1 fusion protein, we have directly demonstrated that Rb positively regulates Sp1 transcriptional activity in vivo. These results indicate that Rb can function as a positive regulator of transcription and that Sp1 is one potential target, either directly or indirectly, for transcriptional regulation by Rb.

Antibacterial activity and penicillin-binding protein affinity of new cephalosporin derivatives in Staphylococcus aureus and Escherichia coli

A series of C3-substituted cephalosporins with different levels of oxidation was synthesized and the activities of eight compounds, including affinity for penicillin-binding proteins (PBPs), in Staphylococcus aureus and Escherichia coli were studied. The more hydrophobic cephalosporins, with a thiophene moiety at the C7 position, were more active than C7-methoxyiminoaminothiazole derivatives against S. aureus H (beta-lactam-susceptible), and compounds with a thioether function at C3 were more active than those with a sulphonyl function at this position. In contrast, the most active compounds against E. coli were hydrophilic, zwitterionic C7-methoxyimino-aminothiazole C3-thioether cephalosporins. The physicochemical properties of the most active compounds were in accord with those predicted for rapid outer membrane penetration. However, among the thiophene cephalosporins the dianionic sulphonyl compounds were more active than the monoanionic thioether derivatives. There was a reasonably good correlation between MICs and PBP affinities for S. aureus H. The compounds had most affinity for PBP 1 and least for PBP 4. The two most potent compounds had high affinities for PBPs 1, 2 and 3. The compounds had low affinities for the beta-lactam-insensitive PBP 2a of methicillin-resistant S. aureus strain DU4916-K7. The novel cephalosporins had the highest affinities for PBPs 1a/1b and 3 of E. coli DCO. The major morphological response of E. coli to the compounds was cell elongation.

High-level expression of human insulin-like growth factor II in Escherichia coli

A gene encoding mature human insulin-like growth factor II (IGF-II) was constructed from the modified IGF-II cDNA sequence and two double-stranded synthetic oligodeoxynucleotide linkers. It was fused to a truncated lacZ gene such that IGF-II was expressed as part of C-terminus of beta-galactosidase. This fused lacZ'-IGF-II gene was under the control of tac promoter and we overproduced the beta-galactosidase-IGF-II fusion protein in the Escherichia coli. The fusion protein formed inclusion bodies inside the cells. The fusion protein was purified from the isolated inclusion bodies and IGF-II protein was obtained from their fusion protein by CNBr cleavage. The released IGF-II was confirmed by its molecular weight as determined by SDS-PAGE and by its ability to bind anti-IGF antibody.

Genetic instability at the adenine phosphoribosyltransferase locus in mouse L cells

Resistance to adenine analogs such as 2,6-diaminopurine occurs at a rate of approximately 10(-3) per cell per generation in mouse L cells. This resistance is associated with a loss of detectable adenine phosphoribosyltransferase activity. Other genetic loci in L cells have the expected mutation frequency (approximately 10(-6)). Transformation of L cell mutants with Chinese hamster ovary cell DNA results in transformants with adenine phosphoribosyltransferase activity characteristic of Chinese hamster ovary cells. No activation of the mouse gene occurs on hybridization with human fibroblasts. That this high frequency event is the result of mutation rather than an epigenetic event is supported by antigenic and reversion studies of the 2,6-diaminopurine-resistant clones. These results are consistent with either a mutational hot-spot, a locus specific mutator gene, or a site of integration of an insertion sequence.

[Susceptibility Of Cockroaches (Blattella Germanica Linneaus) To Various Insecticides]

During the period from May to October 1969, the authors carried out a series of tests with the aim to ascertain the present status of susceptibility of adult cockraoches to various insecticides. The tests on the susceptibility of cockroaches to dieldrin, D.D.V.P., Diazinon; Dibrom, Malathion and lindane were performed with the topical application and the residual film methods under the conditions of 26 degrees C and 80% of relative humidity. The insects tested were collected from Seoul City and were reared at the laboratory. Some of the important results so far obtained can be summarized as follows: 1. The median lethal doses (LD-(50)) of the five insecticides against female adult cockroaches were: 0.4 microgram/roach or 4.02 microgram/body weight (gm) by Dieldrin, 0.29/roach or 2.88 microgram/body weight (gm) by D.D.V.P., 0.29 microgram/roach or 2.96 microgram/body weight (gm) by Diazinon, 0.54 microgram/roach or 5.37 microgram/body weight (gm) by Dibrom, and 2.96 microgram/roach or 29.60 microgram/body weight (gm) by Malathion. And those against male adult cockroaches were: 0.18 microgram/roach or 3.29 microgram/body weight (gm) by Dieldrin, 0.27 microgram/roach or 4.89 microgram/body weight (gm) by D.D.V.P., 0.16 microgram/roach or 2.91 microgram/body weight (gm) by Diazinon, 0.49 microgram/roach or 8.97 microgram/body weight (gm) by Dibrom, and 1.32 microgram/roach or 24.19 microgram/body weight (gm) by Malathion. 2. The level of susceptibility of adult cockroaches to the insecticides tested was 1.0-1.6 times higher as compared with the results obtained on the Japanese Takashi strain. 3. The median knockdown times (LT-(50)) of the female adult cockroaches by insectcides at 1% concentration of 3 mg per square centimetre were 1.82 hours by Malathion, 1.36 hours by Diazinon, 0.56 hours by Lindane, 0.50 hours by Dibrom, and 2.56 hours by D.D.V.P. 4. Amarked difference was seen to exist between the males and the females. The female cockroaches were more resistant than the male to Dieldrin, Diazinon and Malathion.