Gene construction, expression, and characterization of double-copy truncated form of human insulin-like growth factor I

AIM

To increase the production of recombinant truncated form of insulin-like growth factor I [des(1-3)IGF-I], purify the expressed product, and compare its bioactivity with that of standard IGF-I.

METHODS

The second copy of des(1-3)IGF-I gene was inserted into the previously constructed pExSec1/IGF-I to form a pExSec1/2(IGF-I) expression plasmid, then the plasmid was transformed into a protease-deficient E coli strain BL21(DE3). The engineered bacteria were cultured and induced by IPTG at 12 degrees C. The expressed product was purified through ultrafiltration and Sephadex G-50 gelfiltration. The bioactivity of the preliminarily purified protein was tested by MTT method and compared with standard IGF-I.

RESULTS

The amount of des(1-3)IGF-I expressed by pExSec1/2(IGF-I) reached up to 20 % of the total soluble bacterial protein, which was higher than the amount (12 %) expressed by a single copy of pExSec1/IGF-I gene. The purity of recombinant des(1-3)IGF-I reached 49 % and 82 % after ultrafiltration and gelfiltration. The bioactivity of des(1-3)IGF-I after gelfiltration was about 77 % of standard IGF-I at the same concentration.

CONCLUSION

The yield of recombinant des(1-3)IGF-I was increased about 8 % by construction of expression plasmid with two copies of des(1-3)IGF-I gene compared with only one copy of gene, and preliminarily purified des(1-3)IGF-I showed about 77 % bioactivity compared with standard IGF-I.

[Isokinetic concentric dynamometry of knee flexors and extensors in young male]

Objective. To investigate the effects of different moving speeds on isokinetic dynamometry of knee flexors and extensors, and to provide normative data for comparative purposes in strength evaluations. Method. Thirty healthy male were tested at 60, 180, and 240 deg/sec angular velocities using a REV9000 testing and rehabilitation system. Result. Both PT (peak torque) and PT/BW (peak torque/body weights) showed significant differences (P< 0.01, P< 0.05) between flexors and extensors, and declined significantly with increased speed (P< 0.001). Peak torque differences between dominant and nondominant knee (Di%) was 10%. TPT (time to peak torque) tended to decrease as moving speeds increased (P< 0.001). APT (angle of peak torque) were 50%-70% for quadriceps, and 32%-45% for hamstrings; H/Q (hamstrings peak torque/quadriceps peak torque) was 50%-60%; WF (work fatigue) was 65%. Conclusion. The results provided a reference for strength evaluations in space medicine and space physiology, especially under simulated weightlessness and microgravity.

[Effects of some physical training on vestibular function]

Objective. To study the effects of active vestibular conditioning by some physical training on the vestibular function. Method. 10 subjects were given five kinds training gyro wheel, hanging ladder, ripple wood, four column swing and rotating swing for two weeks. Vestibular experimental tests were given before and after training. Result. After physical training, subjects' linear acceleration tolerance time increased significantly, the result of computer dynamic equilibrium posturegraphy demonstrated that the sway of body center of gravity decreased significantly when subjects maintained their equilibrium by both vestibular and visual information. Conclusion. The linear acceleration physical training methods used in this experiment have positive effects, while the methods of angular acceleration training need further investigation.

Insulin-like growth factor I inhibits cardiomyocyte apoptosis and the underlying signal transduction pathways

The effects of insulin-like growth factor I (IGF-I) on cardiomyocyte apoptosis induced by hypoxia in cultured neonatal rat cardiomyocyte were investigated. Primary neonatal rat cardiomyocytes were cultured in 95% N2-5% CO2 to imitate the in vivo hypoxic condition. Electron microscopic observation revealed a series of typical morphological changes characteristic of apoptosis in cardiomyocytes under the hypoxic condition. DNA gel electrophoresis showed DNA laddering in an ischemic duration-dependent manner. The hypoxia-induced cardiomyocyte apoptosis was also evidenced by flow cytometry and TUNEL assay. DNA gel electrophoresis showed that IGF-I in a dose range of 10(-9)-10(-7) mol/l could significantly prevent the hypoxia-induced cardiomyocyte apoptosis. The protective effects of IGF-I against hypoxia-induced apoptosis could also be verified by flow cytometry and TUNEL assay. A tyrosine kinase inhibitor (genistein), a MAPK inhibitor (PD-098059) and a P13 kinase inhibitor (wortmannin) could also suppress the antiapoptotic effects of IGF-I. These results suggest that IGF-I can directly alleviate the hypoxia-induced cardiomyocyte apoptosis and that the three kinase routes mentioned above may be involved in its signaling pathways.

Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and paleobotany

Phylogeny of the Betulaceae is assessed on the basis of rbcL, ITS, and morphological data. Based upon 26 rbcL sequences representing most "higher" hamamelid families, the Betulaceae are monophyletic, with Casuarinaceae as its sister group, regardless of whether the outgroup is Cunoniaceae, Cercidiphyllaceae, Hamamelidaceae, or Nothofagus. Within the Betulaceae, two sister clades are evident, corresponding to the subfamilies Betuloideae and Coryloideae. However, with only 13 phylogenetically informative sites, the rbcL sequences provide limited intra-subfamilial resolution. Internal transcribed spacer (ITS) sequences provided 96 phylogenetically informative sites from 491 aligned sites resulting in a single most parsimonious tree of 374 steps (consistency index = 0.791) with two major lineages corresponding to the two traditional subfamilies: Betuloideae (Alnus, Betula) and Coryloideae (Corylus, Ostryopsis, Carpinus, Ostrya). This arrangement is mostly consistent with those from rbcL and morphology and is greatly reinforced by analyses with the three data sets combined. In the Coryloideae, the Ostryopsis-Carpinus-Ostrya clade is well supported, with Corylus as its sister group. The sister-group relationship between Ostryopsis and the Carpinus-Ostrya clade is well supported by ITS, rbcL, and morphological data. Phylogenetic relationships among the extant genera deduced by these analyses are compatible with inferences from ecological evolution and the extensive fossil record.

[Polymorphism analysis of D19S253 locus in Guangzhou area population]

Frequency data for STR system D19S253 were obtained from 105 unrelated individuals of Guangzhong population. PCR products were detected by horizontal native polyacrylamide gel electrophoresis and a total of 9 alleles were identified by side-by-side comparison with a sequenced allelic ladder prepared by ourselves. The observed genotype distribution conformed with Hardy-Weinberg equilibrium. The high information content found in this system(heterozygosity rate was 0.8353, the mean exclusion chance was 0.7499, the discrimination power was 0.9211, the polymorphism information content was 0.8203) indicated it is a useful means in forensic routine casework both in criminal and paternity cases.

Effect of intrauterine injection of chlorpromazin on implantation in the rat

In rats, injection of chlorpromazin hydrochloride (CPZ), a calmodulin antagonist, to each uterine horn had a significant (87%) anti-implantation effect and 100% antifertility effect. Both of these rates were zero in the saline control group. Polyacrylamide gel electrophoresis analysis of the uterine fluid showed a decrease in the protein content and certain changes in its chemical composition, in particular, a marked reduction in the number of bands of estradiol-induced 70 kD proteins in the experimental group. No significant difference was found in the ovarian weight and the serum estradiol (E2) and progesterone (P) levels between the two groups. These results suggest that calmodulin influences the process of implantation and this effect is not directly related to the serum concentrations of E2 and P. It is believed that CPZ probably exerted its anti-implantation effect by a direct action on the uterus.

A human B-lymphoblastoid cell line constitutively producing Epstein-Barr herpesvirus and JHK retrovirus

The human B-lymphoblastoid cell line, designated JHK-3, with pre-B-cell characteristics, chronically produces two viruses, Epstein-Barr virus (EBV) and JHK virus, an apparently novel retrovirus. The JHK-3 cells are much more productive of extracellular EBV than the high-producer marmoset line B95-8. The extracellular virus of the JHK-3 EBV strain is relatively fragile, more broadly dispersed in an ultracentrifuged sucrose gradient than the B95-8 EBV and more susceptible to disruption by combined treatment with urea and dithiothreitol. By restriction fragment length polymorphism analysis, the JHK-3 EBV strain resembles the EBV strain FF-41. The JHK-3 cells also produce an incompletely characterized, relatively fragile, enveloped, icosahedral RNA virus that contains Mn(++)-dependent reverse transcriptase. JHK virions measure 85 nm in ultrathin sections, much smaller than other Retroviridae. The JHK virus exhibits a distinctive morphogenesis, most nearly resembling C-type retroviruses. The JHK-3 cell line provides a human cell model for investigating virus/virus interactions and their pathogenetic affects on host cells which chronically and simultaneously produce DNA and RNA viruses.

The ultrafiltration and ESR study of Cd2+ binding to human erythrocyte spectrin

The Cd2+ binding to human erythrocyte spectrin tetramer (SPT) was studied by the ultrafiltration method. The results indicate that the Cd2+ binding depends on Cd2+ concentration in a biphasic feature. Thus, it is different from the Tb(3+)-SPT reaction. The biphasic feature is in accordance with the results of fluorescence and circular dichroism (CD) studies on Cd(2+)-SPT complex. The data were analyzed by the Scatchard method. At the first stage (the mole ratio of Cd2+/SPD < 45), there are two types of Cd2+ binding sites, with the binding sites and corresponding binding constants determined as: n1 = 6, K1 = 3.3 x 10(5) M-1; n2 = 8, K2 = 9.1 x 10(4) M-1. At the second state (Cd2+/SPD > 45), the Cd2+ binding manifests a positive cooperative effect. The interaction between Cd2+ and maleimide spin labeled (MSL) SPT was studied by the ESR method. The results were fitted with the multiple equilibrium model, and one Cd2+ high-affinitive binding site with association constant 9.61(7) x 10(5) M-1 was obtained. The conjugation of maleimide with thiol group results in the decrease of Cd2+ high-affinitive binding sites from 6 to 1. This demonstrated that the thiol groups of SPT were involved in the high binding sites. The increase of mobile fraction of MSL in low Cd2+ concentration revealed that Cd2+ binding to SPT induces a significant conformation change of MSL-SPT. The rotation correlation time of MSL attached to SPT varied from 4.4 x 10(-9) to 6.5 x 10(-9) sec.

Tb3+ binding to human erythrocyte spectrin resulting in conformation change and aggregation

The Tb3+ binding to spectrin tetramer (SPT) was studied by Tb3+ fluorescence titration and CD spectra. The results indicated that the total high-affinity Tb3+ binding sites are n1 = 330, with average Kd = 3.6 x 10(-6) M. Among them, ca. 90 sites are of higher affinity and are probably more specific to Tb3+ than the remaining sites. There are 520 low affinity Tb3+ binding sites with average Kd = 1.5 x 10(-5) M. Fluorescence and CD spectra revealed that the alpha-helix content of SPT decreased with Tb3+ binding to specific sites and further binding did not result in conformation change. Tb3+ binding to SPT and the subsequent reactions were studied by employing stopped-flow fluorescence and light scattering methods. The studies demonstrate that this is a multistep reaction assembly: high-affinity terbium binding-conformation change-aggregation-low-affinity terbium binding--the second conformation change. The critical Tb3+ concentration-induced spectrin dimer (SPD) aggregation was determined with a light scattering method.

[A preliminary study of HCV infections with hemophilia and their family members]

28 cases of hemophilia were examined for HCV infection status by using the Kehua anti-HCV ELISA kit of second generation. It was found that the infection rate was 78.5% and the infection rate was even higher with patients who had received transfusions or preparations of coagulatory factors. 10 families of 15 patients were also investigated. It was found that of 15 hemophilia patients, 12 showed positive anti-HCV, while none of their 53 family members exhibited any positive anti-HCV. In 8 children of 9 couples no positive anti-HCV was found. Our results revealed that the hemophilia patient may get infected with HCV by receiving multiple transfusions or preparation of coagulatory factors. The risk of getting infected with HCV via daily-life contact including sexual contact is extremely low.

[Serum soluble interleukin 2 receptor levels in patients with diffuse connective tissue diseases]

Soluble interleukin 2 receptor (SIL-2R) levels in serum appear to reflect the status of lymphocytic activation and proliferation. We examined the levels of serum SIL-2R in 65 patients with diffuse connective tissue diseases by using ELISA method. The mean levels of serum SIL-2R were respectively 0.46 U/L, 0.53 U/L, 0.46 U/L in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and dermatomyositis during disease activity and were significantly higher than those in healthy controls (0.25 U/L). The levels of serum SIL-2R were 0.62 U/L and 0.60 U/L respectively in a patient with mixed connective tissue disease and a patient with systemic sclerosis. The levels of SIL-2R were respectively 0.24 U/L and 0.29 U/L in SLE and RA patients during clinical remission, being significantly lower than during disease activity. SLE patients with high SIL-2R levels were associated with high levels of 125I-DNA rate and erythrocyte sedimentation rate and lower levels of C3 complement components. The measurement of SIL-2R levels may be an useful indicator for monitoring disease activity in SLE and RA patients. Moreover it is a noninvasive method.

[Studies on the T4+2H4+ cell of peripheral blood lymphocyte in systemic lupus erythematosus]

The cell surface phenotype of peripheral blood lymphocytes in patients with systemic lupus erythematosus (SLE) was studied with the anti-T4+, T8+ and T4+2H4+ monoclonal antibodies by flow cytometry. 13 patients with active SLE had a markedly low percentage of T4+2H4+ cells but had normal percentage of T8+ cells. Our results reveal that the influence of T cell to B cell is not only because of the quantity of T cells, also because of the function of T cells. The abnormality of T4+2H4+ cells may be important in the pathogenesis of SLE.

[Blood coagulation changes in systemic lupus erythematosus]

Changes of blood coagulation in 32 cases of SLE were investigated. Abnormalities frequently found were elevation of blood fibrinogen, FDP, V111R: Ag levels, prolonged or shortened KPTT time, and depressed AT-III value. Half of the patients with SLE showed laboratory changes compatible with the diagnostic criteria of DIC, but acute DIC was encountered clinically only in 2 cases hypercoagulation state or hypercoagulation with lower fibrinolysis, however were frequently seen. Lupus anticoagulant were detected in 6 patients and deep vein thrombosis of lower extremity in 1 patient. Examination of blood coagulation in patients with SLE was, therefore, of clinical importance.

Studies on monoclonal anti-isotypic and anti-idiotypic antibodies against leukemia and myeloma: I. Study on monoclonal anti-idiotypic antibodies against lambda chain protein of myeloma

We used lambda chain extracted from urine of patient with myeloma (IgD lambda) as antigen for immunizing BALB/C mice, and 86 hybridoma cell clones secreting monoclonal antibodies (McAb) were obtained after fusing twice and cloning 3-4 times. 15 of these clones secreted monoclonal anti-idiotypic antibodies (anti-Id McAb). The results showed that 12 of 15 anti-Id antibodies reacted only with homologous lambda chain and IgD, not with lambda chain, kappa chain, IgG, IgA, IgM, IgD, IgE, albumin and paraglobulin from normal subjects. Indirect immunofluorescent assay demonstrated that positive reaction rate between anti-Id McAbs and peripheral blood lymphocytes or bone marrow cells of the patient with myeloma was up to 23%. No reaction was observed between anti-Id McAb and peripheral blood lymphocytes or bone marrow cells from normal subjects. Some of these McAbs presented positive reaction with plasmacytoma cell lines cultured in our laboratory.

[The application of plasma exchange therapy in refractory diseases]

115 plasma exchange (PE) procedures were performed in 27 patients using the Haemonetics V50 plasmapheresis system 20 patients improved; among them 15 improved remarkably. Adverse reactions were observed 30 times (26.1%). PE showed beneficial effects in certain disease states which did not respond to conventional treatment or traditionally known therapeutic measures, especially patients in critical condition. Prevention and treatment of associated infections are very important in order to obtain a better efficacy of PE.

Incorporation of 14C acetate into lipids of the ICR mouse lens

Lenses from ICR mice 6, 12 and 35 days of age were incubated with 14C acetate in Medium 199 for 10 hours, and lenses from 35-day-old mice were also incubated for 18 hours. Acetate was incorporated into the phospholipid and free fatty acid fractions. Minimal radioactivity was incorporated into cholesterol. Phosphatidyl choline was the major labeled phospholipid. The longer incubation time resulted in a decrease in the total amount of label retained, indicating a fatiguing of the incubation system. The free fatty acids were extracted and subjected to analysis by gas chromatography. Although myristic acid (14:0) accounted for only 4% to 6% of the free fatty acids, it had the highest specific activity and the greatest percentage of incorporated radioactivity of the fatty acids for the 10-hour incubation period. The specific activity of all the fatty acids decreased dramatically after 18 hours incubation. Palmitic acid (16:0) had the greatest incorporation of label. It was suggested that exogenous acetate in the mouse lens preferentially entered a pool for energy production or storage rather than a pool for the synthesis of structural lipids as evidenced by minimal incorporation into cholesterol.