Determination of a transmembrane segment using cysteine-scanning mutants of transposon Tn10-encoded metal-tetracycline/H+ antiporter

The metal-tetracycline/H+ antiporter is a bacterial plasma membrane protein belonging to the 12-transmembrane transporter family. The boundaries of membrane-embedded domains can be clearly determined by means of a method involving cysteine-scanning mutants and their reactivity to N-ethylmaleimide. The results for 37 cysteine-scanning mutants around putative transmembrane helix 9 indicate that the residues from 266 to 275 and from 296 to 298 form water extruding loops, while residues from 276 to 295 and from 299 to 302 are embedded in the membrane. This method is generally useful for determination of the transmembrane regions of a polytopic membrane protein.

[A case report of an infundibular ventricular septal defect with severe right ventricular outflow tract obstruction due to aneurysm of the aortic sinus of valsalva]

This paper describes the case of a 46-year-old female. Upon contacting infective endocarditis at the age of 39 years, she was diagnosed with a ventricular septal defect (VSD). Because dyspnea gradually worsened, she was later hospitalized. Cardiac catheterization was performed and angiograms were taken, revealing an infundibular VSD accompanied by severe right ventricular outflow tract obstruction (RVOTO) due to aneurysm of aortic sinus of valsalva and to mild aortic regurgitation caused by prolapsing aortic valve. The operative procedure consisted of the closure of the aortic sinus fistula by continuous suture after excision of the aneurysmal sac and patch closure of the VSD without treatment of the prolapsing aortic valve. After the operation, RVOTO improved and aortic regurgitation disappeared. The patient was discharged and has since been well.

A novel neutralization epitope on the 'thumb' subdomain of human immunodeficiency virus type 1 reverse transcriptase revealed by a monoclonal antibody

We have prepared a MAb, 7C4, which inhibits the RNA-dependent DNA polymerase activity of human immunodeficiency virus type 1 (HIV- 1) reverse transcriptase (RT); this MAb has allowed identification of a previously unknown neutralizing epitope of RT. Analysis of the epitope and of the mechanism of polymerase inhibition revealed that 7C4 acts by interfering with the interaction between RT and the template-primer. 7C4 recognizes a discontinuous epitope on the two alpha-helices, alphaH and alpha(I), that make up the 'thumb' subdomain of RT. The existing crystallographic model of HIV-1 RT suggests that the 'thumb' subdomain, together with the 'fingers' and 'palm', form a nucleic-acid-binding cleft in the 66 kDa subunit of RT and that alphaH is in contact with the primer strand of the template-primer. The extent of inhibition of enzyme activity produced by 7C4 correlates with the reported primer-length-dependency of template-primer binding to RT. Inhibition by 7C4 was competitive with respect to the template-primer and mixed with respect to the substrate. Binding of 7C4 to RT was prevented by preincubation of the enzyme with high concentrations of template-primer but not with substrate. Thus, the 7C4 epitope apparently exists on part of the template-primer binding site of the alphaH and alpha(I) regions of the 'thumb' subdomain. This neutralization epitope is a logical target for the development of new types of HIV-1 RT inhibitors.

[A case of internal supravesical hernia]

We report a case of internal supravesical hernia. A 74-year-old male with complaint of abdominal pain underwent an operation for small intestinal obstruction due to its incarceration into the internal supravesical hernia. Retrospectively, the preoperative abdominal CT film showed the relation of the incarcerated intestine, the urinary bladder, and the middle umbilical ligament. This is the first case of the internal supravesical hernia in which the preoperative CT had taken and it will contribute to the preoperative correct diagnosis in the future.

Parathyroid hormone regulates osteoblast differentiation positively or negatively depending on the differentiation stages

The effects of parathyroid hormone (1-34) (PTH (1-34) on osteoblast differentiation were investigated using primary osteoblast-like cells isolated from newborn mouse calvaria. The osteoblast-like cells cultured at low cell densities, in which the cells remained in a subconfluent state at the end of culture, were exposed for 7 days to PTH. This stimulated alkaline phosphatase (ALP) activity in a dose-dependent manner. In contrast, PTH dose-dependently inhibited both ALP activity and osteocalcin production in cells inoculated at high cell densities, in which they had reached a confluent state before the end of culture. The changes of ALP activity by PTH were accompanied with the expression of ALP messenger RNA. PTH induced no changes of the hydroxyproline content in the cell layer when the cells were exposed to the hormone at a subconfluent state, but reduced the content at a postconfluent state. The stimulation of ALP activity by PTH at a preconfluent state was retained even after the removal of PTH from the culture media. The opposite effect of PTH, observed between the preconfluent and the postconfluent state, was reproduced by adding dibutyryl cyclic adenosine monophosphate (cAMP) or forskolin, but not by adding phorbol myristate acetate. In a colony-forming unit fibroblastic (CFU-F) assay, using bone marrow cells isolated from tibiae of 10-week-old mice, PTH induced no changes in the total number of CFU-Fs, but increased the proportion of ALP-positive colonies. These results indicate that PTH exerts opposite effects on the phenotypic expression of osteoblasts, depending on their differentiation stages of osteoblasts. PTH may preferentially stimulate osteoblast differentiation in immature osteoblasts but inhibit it in more mature cells.

Oral adjuvant chemotherapy with carmofur (HCFU) for colorectal cancer: five-year follow-up. Tokai HCFU Study Group--third study on colorectal cancer

BACKGROUND

A joint study was performed by the Tokai HCFU study group, which included seven institutions, to examine the value of oral administration of Carmofur (HCFU), a 5-fluorouracil (5-FU) derivative, for postoperative adjuvant chemotherapy in patients with colorectal cancer undergoing curative resection.

METHODS

The patients were divided into two groups, a control group receiving no HCFU and a group administered HCFU for 1 year, using a centralized registration system by telephone. Among 173 patients entered into this study, 159 evaluable cases were analyzed for evaluation of the drug.

RESULTS

The cumulative 5-year disease-free rate of patients who received HCFU was significantly increased compared with the control group. In particular, the rate was much higher in patients with colon cancer. No severe side effects arose from adjuvant chemotherapy with HCFU.

CONCLUSION

Adjuvant chemotherapy with oral HCFU appears to provide a useful and safe postoperative treatment.

[Effective transcatheter arterial embolization for hepatic metastasis in a case of AFP producing gastric cancer]

We experienced a case of effective transcatheter arterial embolization (TAE) for hepatic metastasis in a AFP producing gastric cancer. A 51-year-old man with 2 type gastric cancer (H0) underwent subtotal gastrectomy (D2). The serum AFP level was 134.3 ng/ml, and AFP positive tumor cells were detected by PAP method. After the operation, the serum AFP level initially decreased but re-increased on the 7th postoperative month, and metastatic lesions of the liver were detected by CT scan. After the patient was treated 4 times by TAE, the serum AFP level returned within normal range and the metastatic tumors of the liver decreased markedly. Therefore liver resection was performed at the 28th month after the first operation. Total necrosis of metastatic liver lesions was confirmed. This patient has been well without recurrence signs for 10 years since operation. It is concluded that TAE should be used to treat hepatic metastasis in the case of an AFP producing gastric cancer.

Changes in fibre types in rat soleus and plantaris muscles following hypophysectomy and compensatory overload

We investigated whether hypophysectomy could modify the change in muscle fibre types caused by compensatory overload. Male Wistar strain rats were assigned to groups of either normal control (NC), hypophysectomized control (HC), normal compensatory overloaded (NO), or hypophysectomized compensatory overloaded (HO). Compensatory overload was induced by the bilateral removal of the gastrocnemius muscle. Five weeks later, there were losses in the soleus and plantaris muscle weights as a result of hypophysectomy. Compensatory overload increased muscle weights independently of the hypophysectomy. Growth hormone and 3,5,3'-triiodothyronine levels were significantly decreased following hypophysectomy. In the soleus, hypophysectomy increased the percentage of type I fibres at the expense of type IIA fibres. Compensatory overload decreased type IIA fibres under the hypophysectomized condition. In the plantaris, the percentage of type IIC fibres was increased at the expense of both type IIA and IIB fibres following hypophysectomy. The decrease in type IIB fibres cause by compensatory overload was induced irrespective of hypophysectomy. The changes in muscle fibre types in the HO group were equal to the sum of the changes in the HC and NO groups. These results suggest that after a period of 5 weeks hypophysectomy may induced decrease in type IIA and IIB fibres in association with the lack of pituitary and thyroid hormones, and that the hypophysectomy could not modify the change in muscle fibre types caused by compensatory overload.

Protective effects of Acanthopanax senticosus Harms from Hokkaido and its components on gastric ulcer in restrained cold water stressed rats

The aim of this study is to investigate the pharmacological effect of the stem bark of Acanthopanax senticosus Harms from Hokkaido (Japanese name: Ezoukogi) in place of the root bark as a restorative tonic on the stress-induced gastric ulcer. In the test, the extract of the stem bark of A. senticosus prepared with hot water was dissolved in water and used for the assay of the protective effect of gastric ulcer (erosion) on stressed rats that were restrained on cold water. The result from a single oral administration of the stem bark of A. senticosus-extract (50, 100 and 500 mg/kg, per day) dissolved in 1 ml distilled water did not show any protective effect on gastric ulcer, but the protective effect was observed in a dose-dependent manner from the oral administration of the extract (50, 100 and 500 mg/kg, per day) for 2 weeks. Pre-administration of the stem bark of A. senticosus-extract in a dose of 500 mg/kg showed the most potent inhibition without affecting either body or adrenal glands weights. Among ether, chloroform, n-butanol and aqueous residue extracts from the stem bark of A. senticosus-extract, the n-butanol extract used for oral administration for 2 weeks showed an obvious inhibition of 61.1% on gastric ulcer, compared with the control group which was treated with distilled water in the same way. Chlorogenic acid and syringaresinol di-o-beta-D-glucoside, as the major components of the n-butanol extract, showed a significantly inhibitory effect on gastric ulcer, at 21.4% and 51.3%, respectively. We suggested that the protective effect of the stem bark of A. senticosus on gastric ulcer may be partially due to those of chlorogenic acid and syringaresinol di-o-beta-D-glucoside.

[Liver resection in a case of multiple liver metastases of gastric cancer following hepatic arterial infusion chemotherapy]

A 61-year-old-man underwent subtotal gastrectomy (D2) for advanced gastric cancer with multiple liver metastases. After the operation, repeated hepatic arterial infusion chemotherapy was performed employing implantable catheter and port system with CDDP and MMC. The result was that the liver tumors showed a remarkable regression in size, and the serum CA 19-9 level decreased within normal range. But the tumor in the lateral segment grew and the CA 19-9 level increased again. There was no evidence of metastasis or recurrence except in the liver, and the metastatic tumors in right lobe became smaller by hepatic arterial infusion chemotherapy at this time. Therefore, lateral segment resection was performed for reductive surgery 14 months after the first operation. After that, the liver tumors did not grow and CA 19-9 kept within the normal range, while hepatic arterial infusion chemotherapy could be given. Thus, it seems that liver resection for reduction surgery following hepatic arterial infusion chemotherapy should be considered as a treatment for multiple liver metastases.

Identification of type I and type II serine/threonine kinase receptors for growth/differentiation factor-5

Growth/differentiation factor-5 (GDF-5) is a member of the bone morphogenetic protein (BMP) family, which plays an important role in bone development in vivo. Mutations in the GDF-5 gene result in brachypodism in mice and Hunter-Thompson type chondrodysplasia in human. BMPs transduce their effects through binding to two different types of serine/threonine kinase receptors, type I and type II. However, binding abilities appear to be different among the members of the BMP family. BMP-4 binds to two different type I receptors, BMP receptors type IA (BMPR-IA) and type IB (BMPR-IB), and a type II receptor, BMP receptor type II (BMPR-II). In addition to these receptors, osteogenic protein-1 (OP-1, also known as BMP-7) binds to activin type I receptor (ActR-I) as well as activin type II receptors (ActR-II and ActR-IIB). Here we investigate the binding and signaling properties of GDF-5 through type I and type II receptors. GDF-5 induced alkaline phosphatase activity in a rat osteoprogenitor-like cell line, ROB-C26. 125I-GDF-5 bound to BMPR-IB and BMPR-II but not to BMPR-IA in ROB-C26 cells and other nontransfected cell lines. Analysis using COS-1 cells transfected with the receptor cDNAs revealed that GDF-5 bound to BMPR-IB but not to the other type I receptors when expressed alone. When COS-1 cells were transfected with type II receptor cDNAs, GDF-5 bound to ActR-II, ActR-IIB, and BMPR-II but not to transforming growth factor-beta type II receptor. In the presence of type II receptors, GDF-5 bound to different sets of type I receptors, but the binding was most efficient to BMPR-IB compared with the other type I receptors. Moreover, a transcriptional activation signal was efficiently transduced by BMPR-IB in the presence of BMPR-II or ActR-II after stimulation by GDF-5. These results suggest that BMPR-IB mediates certain signals for GDF-5 after forming the heteromeric complex with BMPR-II or ActR-II.

Transmembrane glutamic acid residues play essential roles in the metal-tetracycline/H+ antiporter of Staphylococcus aureus

Three transmembrane aspartyl residues play essential roles in the transposon Tn10-encoded metal-tetracycline/H+ antiporter (Tet(B)) [Yamaguchi, A. et al. (1992) J. Biol. Chem. 267, 7490-7498]. The tetK gene-encoding tetracycline resistance protein (Tet(K)) of Staphylococcus aureus mediates metal-tetracycline/H+ antiport similarly to Tet(B); however, it has no transmembrane aspartyl residue. On the other hand, Tet(K) has three glutamyl residues, Glu-30, Glu-152 and Glu-397, in the putative transmembrane regions. In the present work, tet(K) gene was expressed in Escherichia coli and the transport activity was measured in everted membrane vesicles. When these glutamyl residues were replaced with Gln, the tetracycline transport activity was almost completely lost, indicating the important roles of these residues in Tet(K). In the case of Glu-397, even the charge-conserved mutation to Asp caused complete loss of the activity. On the other hand, the mutation of Glu-30 and Glu-152 to Asp resulted in significant retention of transport activity. These results are similar to those on the mutation of the three transmembrane aspartyl residues in Tet(B), indicating that the transmembrane glutamyl residues in Tet(K) play roles similar to those of the transmembrane aspartyl residues in Tet(B).

[The availability of personality traits in the hierarchical structure: an exploration of the "basic level"]

Personality traits have a structure that is hierarchically organized in terms of trait abstractness. Which level of the hierarchy is most available to the person perceiver? We started out with four levels, and tried to determine which was most available and therefore became the "basic level", as in the Rosch, Mervis, Gray, Johnson, and Boyes-Braem's natural categories (1976). Two methods were employed. First, rating of trait descriptiveness showed that information effectiveness was relatively high at the second level from the top. Second, subjects preferred the same level when they described target persons. These results suggested that a "basic level" indeed existed in the hierarchy of personality traits. However, social desirability of traits and who the target person was also affected the results. Implications are discussed about theories of cognitive style, especially cognitive complexity, which assume the generality of our cognitive system and have been in confusion with contradictory findings.

[Pit fall of aprotinin administration during open heart surgery]

Aprotinin administration during open heart surgery has been attempted at various institutions to reduce hemorrhage and improve the rate of no-transfusion operations, and has been reported to be effective. The treatment has been effective also in the 45 patients operated on at our institution. However, we experienced LOS at weaning from extracorporeal circulation (8 cases) considered to be due to aprotinin administration, suggesting unexpected risk of the treatment. Evaluation was made by classifying the patients according to the aprotinin dose; A high-dose group administered aprotinin at 300 x 10(4) units (20 patients), a low-dose group administered aprotinin at 100 x 10(4) units (8 patients), and a control group not administered aprotinin (15 patients). The volume of postoperative hemorrhage increased with the dose of aprotinin, and was significantly lower in the high dose and medium-dose groups than in the control group, but was not significantly different in the low-dose group. The postoperative peak CPK and CPK-MB were not significantly differ but increased slightly with the aprotinin dose. Probably for this reason, IABP was needed in 8 (17.8%) of the 45 patients because of LOS at weaning from extracorporeal circuration. A diagnosis of perioperative myocardial infarction (PMI) was made in 7 of these patients. Factors other than aprotinin are unlikely to be the cause of LOS, and the condition is considered to have been induced by micro-embolism during extracorporeal circulation with aprotinin administration. We propose two points as basis for this speculation. The first is that the body temperature during extracorporeal circuration, which was 30-35 degrees C in the bladder, promoted antifibrinolytic activity of aprotinin. The second is poor control of ACT during extra corporeal circulation. Thus, we suggest the risk of the use of aprotinin without further reduction in the body temperature during extracorporeal circuration. At present avoidance of high body temperatures and strict control of ACT during extracorporeal circulation are important preventive measures against micro-embolism possibly caused by aprotinin.

Acute occlusion of the descending thoracic aorta: report of a case

This report describes the unusual case of an acute occlusion of the descending thoracic aorta in a 52-year-old woman. The patient underwent successful extraanatomical bypass with intraoperative hemodialysis.

Fibromuscular dysplasia of the visceral arteries

Fibromuscular dysplasia (FMD) commonly involves the renal and carotid arteries. However, visceral arterial involvement is rare. We report a 39-yr-old male who developed ischemic bowel disease twice (once in the jejunal artery and once in the sigmoid artery) as a result of FMD. First ischemic change occurred in the sigmoid colon with manifestation of melena and abdominal pain, and the second occurred in the jejunum, with severe abdominal pain and intestinal stenosis. Angiography revealed the "string of beads" appearance, characteristic of FMD, in those two arteries responsible for the ischemic lesions. Fasting therapy with intravenous hyperalimentation improved both lesions, but secondary stenosis caused by ischemia occurred in the jejunum. Surgical resection of the stenotic jejunum was required. Although the abnormal arteries that had been imaged as a "string of beads" on angiography were not resected, the postoperative course has been uneventful and satisfactory.

The two-fire, one-cartridge stapling method using a modified Endo-GIA

The endoscopic stapler (Endo-GIA) was designed to divide tissue between two triple-stapled lines. The endoscopic surgeon frequently encounters situations where only stapling is required. Kirby described a staple closure method that uses a knifeless Endo-GIA cartridge. This method, although useful, has the problem of the modified Endo-GIA unit locking. Therefore, we devised a new technique for endoscopic stapling that involves two consecutive staplings using one cartridge without cutting. This method requires modification of the Endo-GIA system by removing the safety-lock system. In addition to enabling endoscopic stapling techniques without the risk of locking, the method can effect a significant cost savings.

Mercaptide formed between the residue Cys70 and Hg2+ or Co2+ behaves as a functional positively charged side chain operative in the Arg70-->Cys mutant of the metal-tetracycline/H+ antiporter of Escherichia coli

The bacterial tetracycline/H+ antiporter (TetA) mediates active efflux of a chelation complex of tetracycline with a divalent cation such as Mg2+, Co2+, or Mn2+ [Yamaguchi, A., Udagawa, T., & Sawai, T. (1990a) J. Biol. Chem. 265, 4809-4813]. The positive charge of Arg70 in the antiporter is important for the transport function [Yamaguchi, A., Someya, Y., & Sawai, T. (1992c) J. Biol. Chem. 267, 19155-19162]. Out of six site-directed mutants of Arg70, only the Lys70 mutant retained moderate transport activity, whereas the Ser70, Ala70, Trp70, Leu70, and Asp70 mutants had no or extremely low transport activity. In this study, we constructed the Cys70 mutant and found that the Cys70 mutant showed, unexpectedly, a significant activity comparable to that of the Lys70 mutant in the presence of Co2+ ions, whereas it showed very low activity as well as the Ala70 mutant in the presence of Mg2+ or Mn2+ ions. Hg2+, which is known to be a cysteine specific modifier but has no ability to form a complex with tetracycline, caused a dramatic increase in the Vmax value of Co(2+)-dependent tetracycline transport mediated by the Cys70 mutant without affecting the k(m) value, whereas activities of the wild-type and the Lys70 and Ala70 mutants were not affected by Hg2+, Hg2+ alone without Co2+ could not support the transport activity at all, because Hg2+ does not form a chelation complex with tetracycline. These observations suggest that a mercaptide formed between the SH group of Cys70 and Hg2+ or Co2+ works as a positively charged side chain like that of Arg or Lys. When the SH group of the Cys70 mutant was masked with modification by sulfhydryl reagents, the residual activity was no longer affected by Hg2+. Inversely, when the Cys70 mutant was preincubated with Hg2+, it was protected from the inactivation by sulfhydryl reagents. These observations also confirm the mercaptide formation between the Cys70 and a divalent cation as a functional side chain.

HLA-B27 subtypes in Japanese with seronegative spondyloarthropathies and healthy controls

OBJECTIVE

To determine HLA-B27 subtype frequencies in Japanese patients with seronegative spondyloarthropathies (SpA) and healthy controls.

METHODS

We determined HLA-B27 subtypes of 20 Japanese patients with ankylosing spondylitis and one with Reiter's syndrome, and 11 healthy Japanese individuals using a polymerase chain reaction sequence specific oligonucleotide hybridization method specifically designed for the discrimination of B*2701-09.

RESULTS

14 of 21 (67%) patients and 9 of 11 (82%) controls were typed as B*2704. The remainder were B*2705.

CONCLUSION

HLA-B*2704 and B*2705 are present in the Japanese population, the former being the predominant subtype of HLA-B27. Both subtypes are associated with SpA.

Cloning of rat type I receptor cDNA for bone morphogenetic protein-2 and bone morphogenetic protein-4, and the localization compared with that of the ligands

A rat homologue cDNA of mouse (Koenig et al. [1994] Mol. Cell Biol. 14:5961-5974; Suzuki et al. [1994] Proc. Natl. Acad. Sci. USA 91: 10255-10259) and human (ten Dijke et al. [1994] J. Biol. Chem. 269:16985-16988) type I receptors for BMP-2 and BMP-4 was cloned. Tissue distribution of the receptor mRNA was studied by in situ hybridization using rats at embryonic days 9, 13, 15, and 18 as well as 1- and 5-day-old postnatal rats. In the rats at embryonic days 9, 13, and 15, the receptor mRNA was diffusely expressed over the embryonic bodies. At embryonic day 18, the receptor mRNA expression was high in the hair and whisker follicles, tooth bud, cartilage, bone, digestive organs, lung, kidney, heart, and meninges. The receptor mRNA was expressed over a much wider area than those of the ligands in many organs. In the lung and digestive organs, the receptor mRNA was diffusely expressed and most highly expressed in the bronchial epithelium and muscle layer, respectively, in both of which mRNA expression of the ligands was undetectable. The receptor mRNA was highly expressed in the meninges, although neither of the ligands was expressed in or near this region. These results suggest that this receptor participates in both mesoderm formation in early embryogenesis and differentiation of mesodermal cells during maturation of organs, and further suggest the presence of another factor(s) that binds the type I receptor.

[A case of primary tissue failure in aortic bioprosthesis due to pannus formation]

A 22-year-old man, who had received aortic valve replacement with a 21 mm of Carpentier-Edward S.A.V Bioprosthesis for aortic regurgitation at 19 years of age, was readmitted to our hospital because of a new systolic murmur and his chest roentgenogram showed remarkable cardiomegaly. Cardiac catheterization showed a 55 mmHg pressure gradient across the bioprosthesis. Under the diagnosis of primary tissue failure, reoperation was undergone. At reoperation, the sewing ring and leaflets of the prosthesis were covered with pannus, which adhered to leaflets, and the thickness of these leaflets was seen. It was thought that these changes caused aortic stenosis. Primary tissue failure due to pannus formation has been reported a little, but if bioprosthesis is implanted in the supra-annular position, pannus formation may occur because cusps of bioprosthesis are attached to the host's annulus.