[Structure elucidation of glycan of a glycoconjugate SPPA-1 isolated from Spirulina platensis]

AIM

To elucidate the structure of the glycan of SPPA-1, a glycoconjugate isolated from Spirulina platensis.

METHODS

Methylation analysis, GC/MS, and 1D, 2DNMR techniques were used to determine the structures of the glycoconjugate (SPPA-1).

RESULTS

SPPA-1 was only composed of alpha-D-glucose and shown to be a (1-->4) linked alpha-D-glucan to which a few glucosyl side chains are attached at O-6 of the glucosyl residues of the main chain.

CONCLUSION

The glycan of SPPA-1 is a new glucan.

Toosendanin-induced inhibition of small-conductance calcium-activated potassium channels in CA1 pyramidal neurons of rat hippocampus

The effect of toosendanin (TSN) on small-conductance calcium-activated potassium channels (SK(Ca)) in pyramidal neurons of rat hippocampal CA1 region was observed using the inside-out configuration of patch-clamp technique. The results showed that TSN (1.7 approximately 170 microM) inhibited the SK(Ca) activity by reducing the open probability and open frequency significantly in a concentration-dependent manner, and the effects were partially reversible. Elevating Ca2+ concentration at the intracellular side of the patch ([Ca2+](i)) from 1 to 10 microM decreased the inhibitory efficacy. Analysis of the channel kinetics indicated that TSN increased the slow closed time constant significantly, while open time and unitary conductance of channel did not change. These data provide a further explanation for TSN-induced facilitation of neurotransmitter release and antibotulismic effects of the drug.

[Studies on the glycoconjugates and glycans from Lycium barbarum L in inhibiting low density lipoprotein (LDL) peroxidation]

AIM

To determine the effects of glycoconjugates and their glycans from Lycium barbarum L. on inhibiting low density lipoprotein (LDL) peroxidation.

METHODS

Using Cu(2+)-induced oxidation as a model, the oxidative production of thiobarbituric acid-reactive substances (TBARS) and the LDL electrophoresis migration on agarose gel were measured.

RESULTS

The effects of glycoconjugates and their glycans from Lycium barbarum L. on inhibiting LDL peroxidation were different, among them, glycoconjugate LbGp5 showed the best effect on inhibiting LDL peroxidation.

CONCLUSION

The glycoconjugates can inhibit LDL peroxidatin while their glycans showed no effects on inhibiting LDL peroxidation.

[Physico-chemical properties and biological activities of a glycoconjugate SPPA-1 from Spirulina platensis]

AIM

To isolate polysaccharide from Spirulina platensis and determine its sugar position, molecular weight and biological activities.

METHODS

Sephadex G-75 and CM-Sephadex C-50 were used. The sugar position was analyzed by gas chromatography, the molecular weight was determined by GPC. The homogeneity of this glycoconjugate was determined by HPLC and CE. IR and NMR spectra were used to determine the glycosidic linkage.

RESULTS

SPPA-1 was a homogeneous glycoconjugate, its carbohydrate chain was composed of alpha-glucopyranan, carbohydrate content is 91.70%, Nitrogen content was 0.96%, the molecular weight was 69.00 x 10(4), SPPA-1 could eliminate O2-. radicals.

CONCLUSION

SPPA-1 was an antioxidative glycoconjugate from Spirulina platensis.

[Study on the association between interleukin-5 and eosinophil in nasal polyp]

OBJECTIVE

To explore the expression of IL-5 and its role in the formation and development of nasal polyp.

METHOD

31 patients with nasal polyp, 11 patients with chronic sinusitis(CS) and 6 control cases were chosen. Their IL-5 concentration in tissue homogenate were measured by ELISA. All patients with chronic sinusitis, control cases and 15 patients with nasal polyp were chosen to be counted eosinophils in their HE slice.

RESULT

1. The values of IL-5(pg/ml) in nasal polyp, CS and control group separately were: 23.44 +/- 6.68, 16.41 +/- 3.09, 12.86 +/- 4.17. IL-5 concentration in nasal polyp group was higher than that in the other two groups(P < 0.001). 2. The numbers of eosinophils in nasal polyp, CS and control group were 7.42 +/- 2.33, 1.30 +/- 0.59, 1.07 +/- 0.70 separately, the numbers of eosinophils in nasal polyp group were higher than that in CR or control group (P < 0.05).

CONCLUSION

Nasal polyp is a disease characterized by eosinophilia, and IL-5 which activates eosinophil plays part role in the formation of nasal polyp.

Xenotransplantation of microencapsulated bovine chromaffin cells into hemiparkinsonian monkeys

This study examines the effects of xenografts of microencapsulated bovine chromaffin cells (BCCs) on the rotational behavior of hemiparkinsonian monkey recipients. In addition, it determines the content of monoamine neurotransmitters and their major metabolites in the neostriatum in hemiparkinsonian monkeys. The hemiparkinsonian model in monkeys was induced by a unilateral intracarotid injection of methyl-phenyl-tetrahydropyridine (MPTP). Unencapsulated BCCs, BCCs microencapsulated in alginate-polylysine-alginate (ALA) membranes as well as empty microencapsules were grafted into the neostriatum of the hemiparkinsonian monkeys. Following the transplantation the hemiparkinsonian symptoms subsided and the number of rotations induced by apomorphine decreased for up to nine months in the group of recipients grafted with microencapsulated BCCs, while only a temporary improvement (one month) was detected in the recipients of the unencapsulated BCCs. No change was observed in the recipients of empty microencapsules. Dopamine and its metabolites were found considerably depleted in the MPTP-lesioned side versus the unlesioned side of the neostriatum in the hemiparkinsonian monkeys(P<0.05).

Effects of tetrandrine on changes of NMDA receptor channel in cortical neurons of rat induced by anoxia

AIM

To study the effects of tetrandrine (Tet) on the changes of NMDA receptor channels in cortical neurons induced by anoxia.

METHODS

Cell-attached configuration of patch-clamp techniques. Anoxia was produced by perfused cells with 95% N2 + 5% CO2 gassed bath solution.

RESULTS

During anoxia, the open time constant (tau 2), open probability (Po) of 35-pS and 100-pS channels increased. Tet 7.5 mumol.L-1 reduced the Po of 35-pS and 100-pS channels, 15 and 30 mumol.L-1 inhibited open of 100-pS channel fully, and changed the open time constant of 35-pS from two to single exponential distribution.

CONCLUSION

Tet inhibition of the open of NMDA receptor channels induced by anoxia was one of its protective mechanisms.

Dual effects of tetrandrine on calcium-activated potassium channels in pulmonary artery smooth muscle cells

AIM

To study the effects of tetrandrine (Tet) on calcium-activated potassium channels.

METHODS

Inside-out configuration of patch-clamp single channel recording techniques.

RESULTS

Tet 7.5 and 15 mumol.L-1 increased the open probability from control value 0.251 +/- 0.012 to 0.340 +/- 0.013 and 0.415 +/- 0.011, respectively (P < 0.01), decreased the close time from (61 +/- 15) ms to (33 +/- 10) and (28 +/- 11) ms, respectively (P < 0.01). But Tet 30 mumol.L-1 decreased the open probability and open time to (0.114 +/- 0.008) and (1.47 +/- 0.09) ms, respectively [P < 0.01 vs control (0.251 +/- 0.012) and (20 +/- 8) ms].

CONCLUSION

Tet has concentration-dependent dual effects on KCa channels in isolated rat pulmonary smooth muscle cells.

Two Xenopus proteins that bind the 3' end of histone mRNA: implications for translational control of histone synthesis during oogenesis

Translationally inactive histone mRNA is stored in frog oocytes, and translation is activated at oocyte maturation. The replication-dependent histone mRNAs are not polyadenylated and end in a conserved stem-loop structure. There are two proteins (SLBPs) which bind the 3' end of histone mRNA in frog oocytes. SLBP1 participates in pre-mRNA processing in the nucleus. SLBP2 is oocyte specific, is present in the cytoplasm, and does not support pre-mRNA processing in vivo or in vitro. The stored histone mRNA is bound to SLBP2. As oocytes mature, SLBP2 is degraded and a larger fraction of the histone mRNA is bound to SLBP1. The mechanism of activation of translation of histone mRNAs may involve exchange of SLBPs associated with the 3' end of histone mRNA.

The TATA binding protein in the sea urchin embryo is maternally derived

The cDNA encoding the TATA binding protein was isolated from 8- to 16-cell and morula-stage embryonic libraries of two distantly related species of sea urchin, Strongylocentrotus purpuratus and Lytechinus variegatus, respectively. The two proteins are 96% identical over both the N- and C-terminal domains, suggesting a conservation of transcriptional processes between the two species. The prevalence of SpTBP transcripts at several developmental time points was determined using the tracer excess titration method, and the corresponding number of TBP protein molecules was determined by quantitative Western blot analysis. Our results indicate that the amount of TBP mRNA and protein per embryo remains relatively constant throughout development. An initial large pool of TBP protein (>10(9)) molecules in the egg becomes diluted as a consequence of cell division and decreases to about 2 x 10(6) molecules per cell by the gastrula stage. We found by in situ RNA hybridization that the oocyte contains a large amount of TBP mRNA which is depleted late in oogenesis so that the eggs and early embryos have extremely low levels of TBP mRNA. We conclude that the oocyte manufactures nearly all of the TBP protein necessary for embryogenesis.

L-type calcium channel blockade mechanisms of panaxadiol saponins against anoxic damage of cerebral cortical neurons isolated from rats

AIM

To identify the changes of L-type Ca2+ channel on cerebral cortical neurons of rats during anoxia and the protective mechanisms of panaxadiol saponins (PDS) against anoxic injury.

METHODS

Patch-clamp technique of cell-attached configuration and in vitro cerebral anoxic modle built with actuely isolated cortical cells of Wistar rats.

RESULTS

The open time of L-type Ca2+ channel of cortical neurons increased significantly from (2.85 +/- 0.21) ms to (9.1 +/- 1.0) ms (P < 0.01) under anoxia. The particular change was a long-lasting open, which was more than 20 ms in some cases. At the same time, the close time decreased from (38 +/- 8) ms to (10 +/- 3) ms (P < 0.01) and the open-state probability raised from (0.047 +/- 0.008) to (0.165 +/- 0.025) (P < 0.01). PDS (1.5 g.L-1) inhibited the activity of L-type Ca2+ channel both in normal and anoxic condition [open time from (2.23 +/- 0.47) ms and (9.1 +/- 1.0) ms to (1.03 +/- 0.25) ms and (2.1 +/- 0.4) ms; close time from (38 +/- 10) ms and (10 +/- 3) ms to (74 +/- 16) ms and (46 +/- 10 ms); open-state probability from (0.043 +/- 0.006) and (0.165 +/- 0.025) to (0.012 +/- 0.004) and (0.021 +/- 0.009), respectively, P all < 0.01]. The results of PDS were similar to those of verapamil, but were weaker compared with verapamil.

CONCLUSION

The L-type Ca2+ channels of rat cerebral cortical neurons were obviously opened during anoxia. The channels in normal and anoxic condition were effectively blocked by PDS. It was one of the important mechanisms by which PDS protected brain from the anoxic injury.

The mouse histone H1 genes: gene organization and differential regulation

There are six mouse histone H1 genes present in the histone gene cluster on mouse chromosome 13. These genes encode five histone H1 variants expressed in somatic cells, H1a to H1e, and the testis-specific H1t histone. Two of the genes that have not been assigned previously to the five somatic H1 subtypes have been identified as encoding the H1b and H1d subtypes. Three of the H1 genes, H1a, H1c and H1t, are present on an 80 kb segment of DNA that contains nine core histone genes. Two others, H1d and H1e, are present in a second patch, while the H1b gene is at least 500 kb away in a patch containing 14 core histone genes. The histone H1 genes are differentially expressed. All five genes for the somatic histone H1 proteins are expressed in exponentially growing cells. However, the levels of H1a, H1b and H1d mRNAs are greatly reduced in cells that are terminally differentiated or arrested in G0, while the H1c and H1e mRNAs continue to be expressed. In addition to the major RNA that ends at the stem-loop, the H1c gene expresses a longer, polyadenylated mRNA in differentiated cells, although in varying amounts. None of the other histone H1 genes encodes detectable amounts of polyadenylated mRNAs.

The protein that binds the 3' end of histone mRNA: a novel RNA-binding protein required for histone pre-mRNA processing

Replication-dependent histone mRNAs are not polyadenylated but end in a conserved 26-nucleotide structure that contains a stem-loop. Much of the cell cycle regulation of histone mRNA is post-transcriptional and is mediated by the 3' end of histone mRNA. The stem-loop binding protein (SLBP) that binds the 3' end of histone mRNA is a candidate for the factor that participates in most, if not all, of the post-transcriptional regulatory events. We have cloned the cDNA for the SLBP from humans, mice, and frogs, using the recently developed yeast three-hybrid system. The human SLBP is a 31-kD protein and contains a novel RNA-binding domain, which has been mapped to a 73-amino-acid region of the protein. The cloned SLBP is the protein bound to the 3' end of histone mRNA as antibodies specific for the SLBP remove all specific binding activity from nuclear and polyribosomal extracts. These depleted extracts do not cleave histone pre-mRNA efficiently, demonstrating that the SLBP is required for efficient histone pre-mRNA processing.

Characterization of the mouse histone gene cluster on chromosome 13: 45 histone genes in three patches spread over 1Mb

The histone gene cluster on mouse chromosome 13 has been isolated and characterized. Using overlapping YAC clones containing histone genes from chromosome 13, a contig of approximately 2 Mb has been defined. It contains 45 histone genes, organized in three patches containing tightly clustered genes. An 80-kb patch (patch III) containing 12 histone genes is near one end of the contig, and a similar-sized patch (patch I) containing 15 histone genes is near the other end of the contig, located at least 500 kb from the central patch (patch II) of histone genes. The entire cluster contains six histone H1 genes, including the testis-specific histone H1t gene that maps to the middle of the cluster. All nine histone H3 genes in this cluster have been sequenced, and their level of expression determined. Each histone H3 gene is distinct, with five genes encoding the H3.2 protein subtype and four genes encoding the H3.1 protein. They are all expressed, with each histone H3 gene accounting for a small proportion of the total histone H3 mRNA.

Characterization of the 55-kb mouse histone gene cluster on chromosome 3

The histone gene cluster on mouse chromosome 3 has been isolated as a series of overlapping P1 clones, covering 110-120 kb, by probing with the histone H3-614 gene that had been mapped previously to mouse chromosome 3. There are genes for 10 core histone proteins present in a 55-kb cluster within this contig. There are three histone H3 genes, two of which are identical; four histone H2a genes, two of which are identical, one histone H4 gene; and two histone H2b genes. These histone H3 and H2a genes encode approximately 40% of the total H3 and H2a mRNA, whereas the histone H4 and histone H2b genes encode < 10% of the total H4 and H2b mRNA. There are no histone H1 genes present in this cluster. All of the histone H2a genes encode histone H2a.2 proteins (or variants of H2a.2), and account for all the H2a.2 genes in the mouse genome. All three histone H3 genes encode the histone H3.2 protein. A 21-kb region containing the adjacent H3-614 and H2a-614 genes has been duplicated and is present in an inverted repeat separated by 4.5 kb. The other two H2a genes are adjacent, with the 3' ends of their mRNAs separated by only 49 nucleotides in the DNA and the U7 snRNP binding sites separated by only 20 nucleotides. One of the histone H2b genes has lost the stem-loop sequence characteristic of the replication-dependent histone mRNAs and encodes only polyadenylated mRNAs.

Structure of a cluster of mouse histone genes

The structure of a 25 kilobase region of mouse DNA containing 6 functional histone genes and an H2a pseudogene has been determined. The sequences and levels of expression of the H3 and H2b gene as well as the sequence of the H2a pseudogene have been determined.

Hepatocyte growth factor and hepatocyte growth factor receptor in the lacrimal gland, tears, and cornea

PURPOSE

The purpose of this study was to characterize the expression of hepatocyte growth factor (HGF) and HGF receptor proteins in lacrimal gland, tears, and cornea.

METHODS

The reverse transcription-polymerase chain reaction method was used to detect HGF and HGF receptor messenger RNA in human lacrimal gland tissue. HGF and HGF (c-met) receptor monoclonal antibody specificity was demonstrated with fluorescent antibody sorting of cells engineered to express HGF or HGF receptor compared with control cell lines, enzyme-linked immunoadsorbent assay (ELISA), immunoprecipitation, and immunohistology with preabsorption. Immunohistochemistry was applied to study the distribution of HGF and HGF receptor expression in rabbit lacrimal gland tissue and in wounded and unwounded rabbit cornea. An ELISA was used to detect HGF in pooled samples of human tears and individual aliquots of tears collected from patients 1 day after anterior segment surgery.

RESULTS

Amplification products of the expected size for HGF and HGF receptor mRNAs were detected in lacrimal tissue and were confirmed to be specific by hot blotting and nucleic acid sequencing. Hepatocyte growth factor protein was detected in interalveolar and interlobular connective tissue cells adjacent to glandular alveolar (acinar) cells and associated with the cells lining the interlobular ducts. Hepatocyte growth factor receptor protein was expressed in the glandular alveolar and interlobular ductal cells in the lacrimal gland and all three cell types of the cornea. It was detected in keratocyte and endothelial cells, and expression was increased in keratocytes after epithelial wounding. Hepatocyte growth factor was not present in corneal epithelial cells, but in the unwounded cornea a strong signal was associated with the epithelial cell surface. It was detected by ELISA in pooled normal tears at levels 186 to 290 pg/ml and in individual postoperative tear samples at 453 to 619 pg/ml. In some tear samples, HGF levels were below the sensitivity of the assay (97.5 pg/ml).

CONCLUSIONS

The distribution of HGF receptor protein expression in the lacrimal gland suggests that HGF secreted by interalveolar connective tissue cells traverses the acinar cells and modulates functions in acinar and ductal epithelial cells. Hepatocyte growth factor likely collects within the interlobular ducts and becomes a component in normal tears. Thus, lacrimal gland HGF probably modulates corneal epithelial cell proliferation, motility, and differentiation. Its expression in keratocytes is upregulated after corneal epithelial wounding and probably contributes to the epithelial wound healing process.

Forensic pathological expertise of medical tangle analysis of 139 autopsy cases

In this article, we report 139 autopsy cases of medical tangle, which were examined by the Department of Forensic Pathology, Faculty of Medicine, Tongji Medical University from Jan. 1972 to Dec. 1992. The emphasis is put on analyses of the status of medical tangle autopsy in forensic pathology, involved medical departments, distribution of victim's age and sex, differences between clinical diagnosis and autoptical conclusion, the composition and causes of medical tangle. The associated problems in forensic pathological autopsy are also discussed.

Secondary structure of holo- and apo-aminoacylase from prediction, circular dichroism, and FT-Raman spectroscopy

The secondary structures of native (Holo-) and Zn(2+)-free (Apo-) aminoacylase were examined by circular dichroism (CD) and Fourier transform Raman (FT-Raman) spectroscopic techniques and prediction methods. Quantitative analysis of the conformationally sensitive amide I band indicates that Holo- and Apo-enzyme contain 19.3 and 17.2% helical structure, respectively. Far-UV CD spectra of Holo- and Apo-enzyme show that they contain 20.1 and 17.6% alpha-helix, respectively. Secondary structure prediction of aminoacylase indicates that it contains approximately 20.9% alpha-helical structure including 10 alpha-helix segments. The results show that after removal of Zn2+ in aminoacylase, the extent of ordered structure was decreased markedly. The conformation at or near the active site of aminoacylase may contain more ordered structure and the presence of Zn2+ may help to maintain the catalytically active conformation at the active site.

Unfolding, conformational change of active sites and inactivation of creatine kinase in SDS solutions

It has been reported that inactivation occurs before noticeable conformational change can be detected during denaturation of creatine kinase (ATP: creatine N-phosphotransferase, EC 2.7.3.2) and other enzymes by guanidinium chloride or urea. Therefore, Tsou suggested that enzyme active sites may display more conformational flexibility than the enzyme molecules as a whole [Tsou (1986) Trends Biochem. Sci. 11, 427-429; Tsou (1993) Science 262, 380-381]. In this study, the conformational change of the active site, the unfolding of the whole molecule and the inactivation of creatine kinase in solutions of different concentrations of SDS are compared. The results show that, at low SDS concentrations, the conformational change of the active site and inactivation of the enzyme occur to nearly the same extent. However, both of these changes occur at much lower concentrations of SDS than required to significantly unfold the enzyme molecule. The rates of conformational changes of enzyme active sites are markedly faster than those of inactivation. However, at the same SDS concentration, both the inactivation rate and the rate of the active site conformational change are much faster than that of the unfolding of the enzyme molecule as a whole. The above results provide direct evidence of the flexibility of the active site of creatine kinase.

Protective effects of panaxadiol saponins on cardiac functions in burned rats

AIM

To study the effects of panaxadiol saponins (PDS) on burn rat heart functions and try to find its mechanisms.

METHODS

A 35% skin-full-thickness burn was produced by using napalm in Wistar rats. PDS 30 mg kg-1 was injected i.p. to rats immediately after burn and repeated 2 h before examination. Using the isolated perfused working heart and biochemistry methods, heart rate (HR), cardiac output (CO), coronary flow (CF), left ventricular pressure (LVP), aortic pressure (AP), +/- dp/dtmax, and content of malondialdehyde (MDA), activity of superoxide dismutase (SOD) in ventricular myocardium homogenate were examined 8 h after burn.

RESULTS

After burn, HR, CO, CF, LVP, AP, +dp/dtmax, -dp/dtmax, and SOD activity decreased from 206 bpm, 92 mL min-1 g-1, 26 mL min-1 g-1, 7 kPa, 5.9 kPa, 149 kPa s-1, 73 kPa s-1, 2.9 NU/mg protein to 162 bpm, 72 mL min-1 g-1, 14 mL min-1 g-1, 4 kPa, 2.2 kPa, 77 kPa s-1, 44 kPa s-1, 1.7 NU/mg protein, respectively, and MDA content raised from 0.77 nmol/mg protein to 1.35 nmol/mg protein (P all < 0.05). But in PDS-treated group, above decreased or increased dates restored to 202 bpm, 91 mL min-1 g-1, 25 mL min-1 g-1, 6 kPa, 4.1 kPa, 112 kPa s-1, 62 kPa s-1, 2.8 NU/mg protein, 0.91 nmol/mg protein, respectively (P all < 0.05 vs burn).

CONCLUSION

PDS exerts definite protective effects on the cardiac functions after burn injury possibly through its enhancement of SOD activity and the reduction of both the levels of free radicals and lipid peroxides (LPO) of the myocardium.

Conformational changes of active sites during refolding of urea-denatured creatine kinase

The course of the recovery of the active site conformation during refolding of urea-denatured creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2) has been studied. The recovery of the active site conformation has been followed by changes in probe fluorescence of active site of the enzyme labeled by o-phthaldehyde and has been shown to be a triphasic process. A comparison of the rate constants for the conformational recovery of the active site with those for the recovery of enzyme catalytic activity shows that these are synchronized. The results obtained show clearly that, although recovery of partial activity and conformation of the active site occur in reactions with nearly the same rate as those of the refolding processes observed, the complete recovery of the enzyme activity and the active site conformation can only be obtained long after any detectable conformational change of whole enzyme molecule.

[Single channel analysis on calcium channel blockade action of panaxadiol and panaxatriol saponins on cultured rat ventricular myocytes]

Wistar rat ventricular myocytes were isolated. Panaxadiol saponins 1500 micrograms.ml-1, panaxatriol saponins 300 micrograms.ml-1, verapamil 37.5 micrograms.ml-1, or BAY k 8644 5 mumol.L-1 were added into the bath solution separately. The single channel activities of L, T, and B type calcium channels were recorded before and after the administration, using voltage patch-clamp technique in cell-attached configuration. The calcium channel blockade effect of these 2 groups of ginsenosides was authenticated verified. The mechanism existed in the decrease in both the open time and the open-state probability of the calcium channel.

[Detection of human papillomavirus in cervical tissues using polymerase chain reaction]

Detection of human papillomavirus (HPV) 16 and 18 infection by polymerase chain reaction (PCR) was carried out in patients with normal cervix 53 cases, Chronic cervicitis with cervical erosion 59 cases, cervical cancer 12 cases, atypical hyperplasia 3 cases and condyloma acuminatum 2 cases. Results showed that a significantly higher detective rate of HPV-16 and 18 DNA in cervical cancer than in normal cervix, and a higher but not statistically significant positive rate than that in cervical erosion. It indicates that some cases of chronic cervicitis with HPV infection might develop into cervical carcinoma. This finding may help in the early discovery and prevention of cervical cancer.

Kinetics of irreversible inhibition of creatine kinase during modification by o-phthaldehyde

It has been previously reported that, with a fluorescence probe formed from o-phthaldehyde (OPTA) and the thiol and amino groups at or near the active site of creatine kinase, inactivation and exposure of the probe take place simultaneously and well before unfolding of the molecule as a whole. In this study, the inactivation and modification kinetics of purified rabbit muscle creatine kinase by OPTA have been compared, the former by following the substrate reaction in the presence of a previously described inactivator. The microscopic rate constants for the reaction of the inactivator with the free enzyme and with the enzyme-substrate complexes were determined. From the results obtained it appears that OPTA is noncompetitive with respect to both substrates. The inactivation kinetics is monophasic with OPTA, and neither ATP nor creatine alone affect the rate constant of inactivation of the enzyme, indicating that the irreversible inhibition of creatine kinase by OPTA is of the noncompetitive type.

A new murine monoclonal antibody against human hepatoma

A murine monoclonal antibody (MAb 336) reactive with human hepatocellular carcinoma has been raised after immunizing BALB/c mice with whole HepG2 cells. MAb 336 (IgG1) was reactive with HepG2 (whole cells and membrane fractions), but not normal liver or peripheral blood cells. Immunohistological studies indicated that 12/16 hepatocellular carcinoma and 6/11 cirrhotic livers expressed MAb 336-associated antigen, and most normal human tissues and tissues derived from other cancers were unstained. Direct and competitive binding assays ruled out the possibility that this MAb reacts with alpha-fetoprotein, carcinoembryonic antigen, or ferritin. Western blot analysis indicated that MAb 336 reacts with an antigen of approximately 30,000 daltons. This MAb may be potentially useful for studying antigenic expression in hepatocellular carcinoma and as a targeting agent for radioimmunodetection and immunoconjugate therapy.

Purification and characterization of a gamma-like DNA polymerase from Chlamydomonas reinhardtii

A crude in vitro system which initiates chloroplast DNA synthesis near the D-loop site mapped by electron microscopy [Wu, M., Lou, J. K., Chang, D. Y., Chang, C. H., & Nie, Z. Q. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 6761-6765] consists of soluble proteins and proteins extracted from purified thylakoid membrane. In this paper, a DNA polymerase activity was purified to near homogeneity from the soluble protein fraction of this in vitro system by sequential chromatographic separations on heparin-agarose, DEAE-cellulose, and single-stranded DNA-agarose columns and sedimentation in a glycerol gradient. In the glycerol gradient, the enzyme activity sedimented at a position corresponding to a 110-kDa protein. Electrophoretic analysis of the highly purified fraction on SDS-polyacrylamide gel revealed a major polypeptide band with an apparent molecular mass of approximately 116 kDa. In situ DNA polymerase activity assay shows that the DNA polymerization function is associated with the 116-kDa band and an 80-kDa band which could be a subunit of the enzyme. Polymerization activity is inhibited by N-ethylmaleimide, ethidium bromide, and dideoxycytosine triphosphate and is relatively resistant to aphidicolin. Poly(dA).(dT)10 and gapped double-stranded DNA are preferred templates. The purified enzyme contains no exonuclease activity and can initiate DNA replication in a supercoiled plasmid DNA template containing the chloroplast DNA replication origin.

A case of cerebral aspergillosis caused by Aspergillus nidulans. Clinical, pathologic and mycologic identifications

A case of cerebral aspergillosis is reported, the presenting symptom was numbness of right face, which worsened after one year. CT-scan showed two enhanced low-density patches in the anterior and basal parts of right temporal lobe. During operation, an abscess in the deep part of right temporal lobe was revealed. The patient gradually felt amaurosis and oculomotor palsy of right eye. About six months later, she died from intracranial hypertension. Biopsy, as well as autopsy findings suggested fungal infection, and was identified as Aspergillus nidulans, which has probably never been reported in the literature.

Carcinoembryonic antigen and alpha-fetoprotein expression and monoclonal antibody targeting in a human hepatoma/nude mouse model

Hep G2, a human hepatocellular carcinoma, was grown s.c. in nude mice, as well as in tissue culture. This line retains the normal liver parenchymal cell capacity to synthesize human plasma proteins such as albumin, but there is no indication that it harbors the hepatitis B virus. We have detected the oncofetal antigens alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) in both Hep G2 xenografts and spent tissue culture media by Ouchterlony double diffusion assays, enzyme-linked immunosorbent assay, and immunohistology. By enzyme-linked immunosorbent assay, the AFP levels were 544.9 ng/ml in the cell culture and 1.6 microgram/g in saline extracts of the xenograft. The CEA levels were 35.2 ng/ml in the cell culture and 5.4 micrograms/g in the xenograft. The biodistribution of a radioiodinated anti-AFP murine monoclonal antibody and an anti-CEA monoclonal antibody were studied separately in nude mice bearing s.c. Hep G2 xenografts in comparison to an isotype-matched irrelevant IgG (Ag8). Anti-CEA antibody showed a preferential localization for Hep G2, but anti-AFP antibody did not. Immunohistochemical studies of the Hep G2 tumor, using biotinylated anti-AFP and anti-CEA, indicate both cytoplasmic and luminal staining of CEA and AFP in the tumor. These results suggest that Hep G2 may be a useful cell line for radioimmunodetection and radioimmunotherapy studies using anti-CEA and possibly anti-AFP monoclonal antibodies.