Molecular basis of a hereditary type I protein S deficiency caused by a substitution of Cys for Arg474

The molecular basis for a hereditary type I protein S (PS) deficiency was investigated. DNA sequence analysis in the proband showed a novel missense mutation substituting Cys (TGT) for Arg474 (CGT) that is a highly conserved amino acid residue among the related proteins. This missense mutation cosegregated with the type I PS deficiency in this family. Transient expression studies showed that the secretion of the recombinant Cys-mutant PS was markedly decreased compared with that of the recombinant wild-type PS, reproducing the observed phenotype of type I deficiency. Stable expression and pulse-chase experiments demonstrated an intracellular degradation and an impaired secretion of the recombinant Cys-mutant PS. Furthermore, the substitution of Arg474 by Ala or Glu, but not by Lys, markedly reduced the secretion of the recombinant PS mutants in transient expression studies, suggesting that a positively charged basic amino acid might be needed at residue 474 and might play a key role in the protein structure and conformation of the sex hormone binding globulin-homology domain of the PS molecule. We postulate that the loss of the highly conserved Arg474 might be responsible for the type I PS deficiency inherited in this family.

A dual computed tomography linear accelerator unit for stereotactic radiation therapy: a new approach without cranially fixated stereotactic frames

PURPOSE

To perform stereotactic radiation therapy (SRT) without cranially fixated stereotactic frames, we developed a dual computed tomography (CT) linear accelerator (linac) treatment unit.

METHODS AND MATERIALS

This unit is composed of a linac, CT, and motorized table. The linac and CT are set up at opposite ends of the table, which is suitable for both machines. The gantry axis of the linac is coaxial with that of the CT scanner. Thus, the center of the target detected with the CT can be matched easily with the gantry axis of the linac by rotating the table. Positioning is confirmed with the CT for each treatment session. Positioning and treatment errors with this unit were examined by phantom studies. Between August and December 1994, 8 patients with 11 lesions of primary or metastatic brain tumors received SRT with this unit. All lesions were treated with 24 Gy in three fractions to 30 Gy in 10 fractions to the 80% isodose line, with or without conventional external beam radiation therapy.

RESULTS

Phantom studies revealed that treatment errors with this unit were within 1 mm after careful positioning. The position was easily maintained using two tiny metallic balls as vertical and horizontal marks. Motion of patients was negligible using a conventional heat-flexible head mold and dental impression. The overall time for a multiple noncoplanar arcs treatment for a single isocenter was less than 1 h on the initial treatment day and usually less than 20 min on subsequent days. Treatment was outpatient-based and well tolerated with no acute toxicities. Satisfactory responses have been documented.

CONCLUSION

Using this treatment unit, multiple fractionated SRT is performed easily and precisely without cranially fixated stereotactic frames.

Protein C Nagoya, an elongated mutant of protein C, is retained within the endoplasmic reticulum and is associated with GRP78 and GRP94

Protein C Nagoya, an elongated variant of the human protein C, is retained and degraded within the cells in which it is produced (Yamamoto et al, J Clin Invest 90:2439, 1992). To determine the subcellular localization of the protein C Nagoya, the recombinant protein C bearing this mutation was expressed in Chinese hamster ovary (CHO) cells. The mutant protein C was not secreted from the cells and remained susceptible to endo-beta-N-acetylglucosaminidase H (endo H). Immunoelectron microscopy indicated that protein C Nagoya was retained in the endoplasmic reticulum (ER), whereas wild-type protein C was observed in both the ER and the Golgi apparatus. Metabolic radiolabeling with [35S] methionine in combination with chemical cross-linking showed that the protein C Nagoya existed in the ER as a complex with 78-kD glucose-regulated protein (GRP78) and 94-kD glucose-regulated protein (GRP94). Because both GRP78 and GRP94 associate to a far lesser degree with wild-type protein C than with protein C Nagoya, our data suggest that both stress proteins function as molecular chaperones and work in concert with the folding and assembly of protein C. These findings extend our understanding the molecular pathogenesis of protein C deficiency.

Alterations in the DNA topoisomerase IV grlA gene responsible for quinolone resistance in Staphylococcus aureus

A 4.2-kb DNA fragment conferring quinolone resistance was cloned from a quinolone-resistant clinical isolate of Staphylococcus aureus and was shown to possess a part of the grlB gene and a mutated grlA gene. S-80-->F and E-84-->K mutations in the grlA gene product were responsible for the quinolone resistance. The mutated grlA genes responsible for quinolone resistance were dominant over the wild-type allele, irrespective of gene dosage in a transformation experiment with the grlA gene alone. However, dominance by mutated grlA genes depended on gene dosage when bacteria were transformed with the grlA and grlB genes in combination. Quinolone-resistant gyrA mutants were easily isolated from a strain, S. aureus RN4220, carrying a plasmid with the mutated grlA gene, though this was not the case for other S. aureus strains lacking the plasmid. The elimination of this plasmid from such quinolone-resistant gyrA mutants resulted in marked increases in quinolone susceptibility. These results suggest that both DNA gyrase and DNA topoisomerase IV may be targets of quinolones and that the quinolone susceptibility of organisms may be determined by which of these enzymes is most quinolone sensitive.

Structural organization and promoter activity of the human ryudocan gene

To better understand the regulation of ryudocan (syndecan-4) expression, we have determined the structural organization of the human ryudocan gene. The human ryudocan gene extends approximately 24 kilobases and is divided into five exons, which appear to be conserved in syndecan family members. Exon I encodes the signal peptide; exons II-IV, the extracellular domain; and exon V, the transmembrane and cytoplasmic domains, which are highly homologous among syndecan family members. Primer extension analysis showed that human ryudocan gene had a single transcription initiation site, located 3 bases upstream from the described cDNA [Kojima et al. (1993) BBRC 190, 814-822]. The 5'-flanking sequences of human ryudocan gene contain a TATA-like sequence as well as a variety of other potential binding sites for transcription factors, including Sp1, Ap-2, NF-kB, E-alpha H box, H4TF-2, and LBP-1, and were capable of functioning as a promoter. The determination of the human ryudocan gene structure will allow elucidation of constitutive, cell-specific, tissue-specific, and developmentally regulated expression.

Phospholipid composition dependence of Ca2+-dependent phospholipid binding to the C2A domain of synaptotagmin IV

Synaptotagmins I and II are Ca2+- and phospholipid-binding proteins of synaptic vesicles that may function as Ca2+ receptors for neurotransmitter release via their first C2 domains. Herein, we describe the phospholipid binding properties of C2A domains of multiple synaptotagmins (II-VI). We demonstrate that all synaptotagmins can bind negatively charged phospholipids (phosphatidylserine (PS) and phosphatidylinositol (PI)) in a Ca2+-dependent manner, although it was previously reported that synaptotagmins IV and VI do not bind phospholipids. The Ca2+-dependent interaction of the C2A domain of synaptotagmin IV with PS was found to have two components with EC50 values of approximately 5 and 120 microM free Ca2+ and exhibited positive cooperativity (Hill coefficient of approximately 2 for both components). This value is lower than that of the C2A domain of synaptotagmin II (Hill coefficient of approximately 3). All other isoforms bound PS with high affinity (EC50 of 0.3-1 microM free Ca2+; Hill coefficient of 3-3.5). In addition, the C2A domain of synaptotagmin IV cannot bind liposomes consisting of PS (or PI) and phosphatidylcholine, PC (or phosphatidylethanolamine, PE) (1:1, w/w), indicating that the binding to negatively charged phospholipids is inhibited by the presence of PC or PE. In contrast, other isoforms bound all of the liposomes, which include either PS or PI, in a Ca2+-dependent manner. Mutational analysis indicated that this phospholipid composition-dependent Ca2+ binding of synaptotagmin IV results in the substitution of Asp for Ser at position 244. The cytoplasmic domain of synaptotagmin IV also shows this unique phospholipid binding. However, it binds PS with a positive cooperativity and an affinity similar to those of the C2A domains of other isoforms. Our results suggest that synaptotagmin IV is also a potential Ca2+ sensor for neurotransmitter release.

Rapid analysis of amphetamines in blood using head space-solid phase microextraction and selected ion monitoring

A simple and rapid method for analysis of methamphetamine (MA) and amphetamine (AP) in blood was developed using head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry/electron impact ionization-selected ion monitoring (GC-MS/EI-SIM). A vial containing a blood sample, sodium hydroxide, and pentadeuterated methamphetamine as an internal standard, was heated at 80 degrees C for 20 min. The extraction fiber of the SPME was exposed for 5 min in the head space of the vial. First, heptafluorobutyric anhydride solution was injected into the injection port of the GC-MS to make heptafluorobutyramide (HFB) derivatives of amphetamines, and compounds absorbed on the fiber were detached by exposing the fiber in the injection port. Straight calibration curves of MA and AP were obtained from 0.01 to 2 micrograms/g in blood, respectively. No interfering substances were found, and the time for analysis was 30 min for one sample.

[A case of SLE with the onset of pleuritis showing eosinophilia and elevation of serum IgE]

A 19 year old female was admitted to our hospital with complaints of fever, dyspnea and chest pain. Chest x-ray film showed a massive right pleural effusion. She was diagnosed to have systemic lupus erythematosus (SLE) because of malar rash, serositis (pleuritis), positive antinuclear antibody and positive anti-DNA antibody. Then she was successfully treated with 50 mg/d prednisolone. This case was unusual and of interest in that she had eosinophilia in the peripheral blood and exudative pleural effusion and a marked elevation of serum IgE level despite no history of allergic diseases and no evidence of parasite infections.

Effect of heat stress on development in vitro and in vivo and on synthesis of heat shock proteins in porcine embryos

The present study was conducted (1) to examine the effect of an acute increase in ambient temperature on the development of porcine day 6 embryos in culture and after transfer to recipient gilts, and (2) to analyze intracellular production of heat shock proteins (hsps). The viability of porcine day 6 embryos following a temporary acute elevation in ambient temperature (at 42 degrees-45.5 degrees C and for 10-180 min) was examined. Synthesis of 70 kDa hsp (hsp70) and 90 kDa hsp (hsp90) was determined by SDS-PAGE and Western blot analysis in porcine day 6 embryos subjected to heat stresses. Nonheat-stressed embryos were considered as control. Significantly higher numbers of viable nuclei were observed in treatment groups of 42 degrees C-10 min (236.6 +/- 71.4; P < 0.05) and 43 degrees C-30 min (276.8 +/- 89.4; P < 0.005) compared to control (173.9 +/- 53.9). The 42 degrees C-180 min group (158.0 +/- 27.1 microns) had a greater increase in diameter after 24 hr in culture following heat stress compared to control (82.5 +/- 47.3 microns), while heat stress with 43 degrees C for > or = 60 min, 44 degrees-44.5 degrees C for > or = 30 min, or 45 degrees-45.5 degrees C for > or = 10 min impaired their survival, as assessed by differences in number of viable nuclei. The embryos subjected to heat stresses under the conditions of 42 degrees C-180 min, 43 degrees C-10 min, 43 degrees C-30 min, 44 degrees C-10 min, or 45 degrees C-10 min developed to normal piglets after transfer to recipient gilts. Overall pregnancy rate was 75% (6/8), and farrowing rate 62.5% (5/8). Of heat-stressed embryos transferred, 59% (36/61) developed to normal piglets. Heat-stress conditions of 42 degrees C for 180 min, 43 degrees C for 30 min, 44 degrees C for 10 min, and 45 degrees C for 10 min were determined as critical with respect to the in vitro and in vivo survival of porcine embryos. Porcine day 6 embryos constitutively synthesized hsp70 even without heat stress, while hsp90 was detected only at trace level. Neither hsp70 nor hsp90 levels increased in the embryos subjected to heat stresses. In conclusion, porcine day 6 embryos could continue to develop in vivo or during in vitro culture after exposure to acute and temporary rise in temperature. However, no increase of hsp70 and hsp90 was observed in the heat-stressed porcine embryos, while hsp70 was detected in the nonheat-stressed porcine embryos. The precise mechanism of the thermotolerance was unclear.

Changes in cellular distribution of connexins 32 and 26 during formation of gap junctions in primary cultures of rat hepatocytes

In the adult rat hepatocyte, gap junction proteins consist of connexin 32 (Cx32) and connexin 26 (Cx26). Previously, we reported that both Cx32 and Cx26 were markedly induced and maintained in primary cultures of adult rat hepatocytes. The reappearing gap junctions were accompanied by increases in both the proteins and the mRNAs, and they were well maintained together with extensive gap junctional intercellular communication (GJIC) for more than 4 weeks. In the present study, we examined the cellular location of the gap junction proteins and the structures in the hepatocytes cultured in our system, using confocal laser microscopy and immunoelectron microscopy of cells processed for Cx32 and Cx26 immunocytochemistry and freeze-fracture analysis. In immunoelectron microscopy, the size of Cx32-immunoreactive gap junction structures on the plasma membrane increased with time of culture, and some of them were larger than those in liver sections in vivo. Freeze-fracture analysis also showed that the size of gap junction plaques increased and that the larger gap junction plaques were composed of densely packed particles. These results suggest that in this culture system, not only the synthesis of Cx proteins but also the size of the gap junction plaques was increased markedly. In the adluminal lateral membrane of the cells, Cx32-immunoreactive lines were observed and many small gap junction plaques were closely associated with a more developed tight junction network. In the basal region of the cells, small Cx32- and Cx26-immunoreactive dots were observed in the cytoplasm and several annular structures labeled with the antibody to Cx32 were observed in the cytoplasm. These results indicated the formation and degradation of gap junctions in the cultured hepatocytes.

Human ryudocan from endothelium-like cells binds basic fibroblast growth factor, midkine, and tissue factor pathway inhibitor

Ryudocan, a heparan sulfate proteoglycan, was isolated from human endothelium-like EAhy926 cells by a combination of ion-exchange and immunoaffinity chromatography. Purified human ryudocan has biochemical properties similar to those of rat ryudocan isolated from microvascular endothelial cells. Human ryudocan contains only heparan sulfate (HS) glycosaminoglycan chains along with a core protein with an apparent molecular mass of 30 kDa. We evaluated the interactions between purified human ryudocan and several extracellular ligands by using a solid-phase binding assay. We found that basic fibroblast growth factor (bFGF), midkine (MK), and tissue factor pathway inhibitor (TFPI) exhibit significant ryudocan binding. Heparitinase (but not chondroitin ABC lyase) treatment destroyed the ability of ryudocan binding to bFGF, MK, and TFPI. Heparin and HS, but not chondroitin sulfate, inhibited such ryudocan binding. Thus, the HS chains of ryudocan appear to be responsible for its binding to bFGF, MK, and TFPI. The apparent dissociation constants for purified ryudocan were as follows: bFGF, 0.50 nM; MK, 0.30 nM; and TFPI, 0.74 nM. Immunohistochemical analysis revealed that ryudocan was expressed in fibrous connective tissues, peripheral nerve tissues, and placental trophoblasts. These findings suggest that ryudocan may possess multiple biological functions, such as bFGF modulation, neurite growth promotion, and anticoagulation, via HS-binding effectors in the cellular microenvironment.

Effects of oxygen radical scavengers on connexins 32 and 26 expression in primary cultures of adult rat hepatocytes

Although we recently reported our success in inducing and maintaining the gap junction proteins connexin 26 (Cx26) and connexin 32 (Cx32) in adult rat hepatocytes cultured in serum-free L-15 medium supplemented with epidermal growth factor, dimethylsulfoxide (DMSO) and glucagon, the mechanisms by which DMSO induces gap junctions are still not clear. It is known that DMSO is not only a differentiation reagent for various cells but also a powerful scavenger of oxygen radicals. In the present study, by using this culture system and the measurement of oxidative stress by the nitro blue tetrazolium (NBT) formazan assay, we have examined the effect of oxygen radical scavengers such as DMSO, dimethylthiourea (DMTU) and alpha-tocopherol on the expression of both Cxs and on gap junctional intercellular communication (GJIC), as compared to another differentiation reagent, hexamethylene-bis-acetamide (HMBA). DMSO and DMTU clearly inhibited the oxidative stress of the cultured hepatocytes, while alpha-tocopherol and HMBA did not. The expression of Cx26 and Cx32 in the cultured hepatocytes was markedly induced by DMSO and DMTU. Furthermore, extensive GJIC was also observed with DMSO and DMTU. These results suggest that the expression of gap junctions in the hepatocytes may be closely related to oxidative stress and that oxygen radical scavengers may be important substances in inducing this expression.

Pretreatment with T cell receptor peptides using a conventional immunization protocol does not induce effective protection against autoimmune encephalomyelitis

It was previously reported that vaccination with synthetic peptides corresponding to the CDR2 or CDR3 region of T cell receptor (TCR) protected susceptible animals from the development of experimental autoimmune encephalomyelitis (EAE). However, recent studies by several research groups have revealed that TCR peptide therapy often confers little or no protection from autoimmune disease. In the present study, we attempted to find more appropriate peptides that is capable of conferring effective protection against the development of EAE. Four peptides corresponding to parts of the V beta region (13-23, 24-36, 39-59, and 64-74) were selected by epitope scanning and hydrophilicity searching, and their protective abilities were tested. All these peptides were, however, ineffective in protecting rats from the disease. We also generated three different synthetic peptides corresponding to the TCR J region of encephalitogenic T cells. Vaccination with the J-region peptides did not protect animals from the development of EAE. Rather, one of the peptides (V beta-DSS-J beta 2.6) enhanced the clinical severity of EAE and induced fatal disease in some rats. Taken together, TCR peptide therapy appears to be generally ineffective and elucidation of the mechanism by which EAE is enhanced after TCR peptide vaccination should provide insight into the pathogenesis of this disease.

Bacillus stearothermophilus cell shape determinant gene, mreC and mreD, and their stimulation of protease production in Bacillus subtilis

Protease production stimulating genes were isolated from a soybean protein degrading bacterium, Bacillus stearothermophilus HA19. The cloned fragment stimulated production of a 37-kDa protease in B. subtilis. The nucleotide sequence of the genes and their flanking regions were identical to the B. subtilis cell shape determinant genes mreC and mreD [J. Bacteriol., 176, 6729-6742 (1992); J. Bacteriol., 176, 6717-6728 (1992)]. The mreC and mreD genes in B. subtilis stimulate secretion of a neutral protease (37-kDa), and the protease activity in the culture medium reached 2500 U per ml (approximately 10 times higher than the host strain) after 24 h of cultivation in L broth, suggesting the mreCD genes regulate protease expression and the protease is related to the cell shape determination in Bacilli. The protease productions in B. subtilis carrying mreC or mreD deletion plasmids were not elevated, so the 37-kDa protease stimulation requires both mreC and mreD genes. The extracellular protease was purified, and the molecular mass of the enzyme was 37,000 Da by SDS-polyacrylamide gel electrophoresis and gel filtration. The optimum pH and temperature for the enzyme activity were 7.0 and 50 degrees C, respectively, and the enzyme was stable at pH 7-10. The enzyme was inactivated by EDTA, but not by phenylmethyl sulfonyl fluoride and diisopropyl fluorophosphate.

ErbB-2 expression is correlated with poor prognosis for patients with osteosarcoma

BACKGROUND

It has been reported that the c-erbB-2 protooncogene is frequently amplified and overexpressed in many types of cancers, except sarcomas and hematological malignancies.

METHODS

Expression of ErbB-2 in the tumors of 26 patients with conventional osteosarcoma was evaluated by immunoblotting. DNA from osteosarcoma tissues that expressed ErbB-2 were analyzed by Southern blot hybridization to examine gross rearrangement of the gene. The DNA was also surveyed for the presence of genetic mutation in the transmembrane domain of ErbB-2 by polymerase chain reaction-single-stranded DNA conformation polymorphism analysis. In addition, possible correlation of ErbB-2 expression with gender, age, histopathologic subtype, and response to chemotherapy was analyzed. Survival analysis was performed by the Kaplan-Meier test using the approximate chi-square statistic for the log-rank test.

RESULTS

The ErbB-2 protein was detected in 11 of 26 osteosarcoma tissues (42%) by immunoblot analysis. Expression of ErbB-2 was confirmed by immunohistochemical studies using specific anti-ErbB-2 monoclonal antibody. However, neither amplification of the c-erbB-2 gene nor evidence of significant genetic mutation was found in these osteosarcomas. Expression of ErbB-2 examined by immunoblotting was most strongly correlated with early pulmonary metastases (P < 0.05). Among the entire group of 26 patients in this study, Kaplan-Meier life table survival of the patients with apparent ErbB-2 expression was significantly worse than that of the patients with little ErbB-2 expression (P < 0.01).

CONCLUSIONS

In 42% of the osteosarcomas, the tumor cells expressed ErbB-2. Expression of ErbB-2 was strongly correlated with early pulmonary metastasis and poor survival rate for the patient. These data suggest that ErbB-2 plays a significant role in aggressive tumor growth and in the promotion of metastatic potential in osteosarcomas. ErbB-2 in the osteosarcoma tissues would be a useful prognostic marker for patients.

Human trehalase: characterization, localization, and its increase in urine by renal proximal tubular damage

By using polymerase chain reaction, cDNA encoding human renal trehalase has been isolated. The partial amino acid sequence deduced by the cDNA showed homologies in rabbit, Tenebrio molitor and silkworm trehalase. Northern blots showed renal trehalase mRNA to be about 2.0 kb. To examine the properties of renal and urinary human trehalase, the trehalase cDNA was inserted in the pMAL-cRI vector downstream from the malE gene, which encodes maltose-binding protein. Transfection of the recombinant pMAL-cRI in Escherichia coli provided high levels of expression of the maltose binding protein-trehalase fusion protein. A rabbit was immunized with purified fusion protein, and antihuman trehalase antibodies were obtained. Immunoblot analysis disclosed that renal and urinary trehalase exhibited a molecular mass of about 75 kDa. Analysis by indirect fluorescent microscopy demonstrated that the enzyme located in only proximal tubular cells. Urinary trehalase activity was low in the healthy infants and elevated in patients with asphyxia. Markedly high activity was observed in a patient with Lowe syndrome. The immunoreactive urinary trehalase with 75 kDa was increased dependent on the elevation of the activity. On the basis of these findings, we conclude that the increase of urinary trehalase reflects the extent of renal tubular damage, and we propose that urinary trehalase can be a specific marker of renal tubular damage.

Endothelin-1 has a priming effect on production of superoxide anion by alveolar macrophages: its possible correlation with bronchopulmonary dysplasia

The purpose of this study was to clarify the role of endothelin (ET)-1 in the development of bronchopulmonary dysplasia (BPD). Tracheal aspirates were obtained from 27 newborn babies with respiratory distress (13 with BPD and 14 without BPD) who were mechanically ventilated. Production of superoxide anion (O2-) by rabbit alveolar macrophages was determined by preincubation with the tracheal aspirate supernatant (TAS) and stimulation with phorbol myristate acetate (PMA). O2- production was demonstrated only when PMA was added to the experimental system and was enhanced with TAS of infants who later developed BPD compared with TAS from infants without BPD. The effects of ET-1 and ET-3 on O2- production and the blockade by anti-ET-1 antibody and BQ123 (ET A receptor antagonist) were also examined. The enhancing effect was blocked by either anti-ET-1 antibody or BQ123. PMA-stimulated production of O2- increased when cells were preincubated with several doses of ET-1 (5 x 10(-13) to 2 x 10(-12) M), whereas ET-3 was without effect. TAS contained significant amounts of immunoreactive ET-1, and there was a close positive correlation (r = 0.764) between the activity of O2- production and immunoreactive ET-1 levels in TAS samples. These results may be interpreted to indicate that ET-1 synthesized by and secreted from tracheal epithelial cells and/or alveolar macrophages has a priming effect on alveolar macrophages to produce O2-, thus possibly contributing to the development of BPD.