Secretion cloning vectors in Escherichia coli

The DNA fragment coding for the signal peptide of the OmpA protein, a major outer membrane protein of Escherichia coli, has been inserted into the high-level expression vectors, pIN-III. A foreign DNA fragment can be cloned in any one of the three reading frames at the unique EcoRI, HindIII or BamHI sites immediately after the ompA signal peptide coding sequence. The cloned foreign gene is under the control of both the lpp promoter and the lac promoter-operator. The expression of the gene is regulated by the lac repressor produced by the same vectors. Using the pIN-III-ompA vector, the DNA fragment coding for only the mature portion of beta-lactamase was inserted into the EcoRI site. Upon induction of gene expression, beta-lactamase was secreted into the periplasmic space. The ompA signal peptide was correctly removed resulting in the production of beta-lactamase with four extra amino acid residues (Gly-Ile-Pro-Gly) at its amino terminus due to the linker sequence in the vector. After a 3-h induction, beta-lactamase was accumulated to 20% of total cellular protein without any detectable accumulation of pro-beta-lactamase. Using oligonucleotide-directed site-specific mutagenesis, we have also removed the linker sequence and upon induction of gene expression, beta-lactamase with the authentic NH2-terminal sequence was produced, in even larger amounts than the beta-lactamase with the linker sequence.

Correlation between histopathologic features and magnetic resonance images of spinal cord lesions

The authors report a correlation between histopathologic features and magnetic resonance images of spinal cord lesions in 19 human spinal cords with various types of lesions. Abnormally high T2-weighted image signal intensities appeared nonspecifically in mildly altered lesions or areas with edema. In the gray matter, a low T1-weighted image in addition to a high T2-weighted image signal intensity appeared in severely altered lesions with necrosis, myelomalacia, or spongiform change. In the white matter, abnormally high T1-weighted image intensities appeared in severely altered lesions. Based on these preliminary results, it appears that a correlation between the degree of histopathologic alteration of the spinal cord and magnetic resonance images in clinical cases can be made. This is the first study to clarify the correlation between histopathologic features and magnetic resonance images of the diseased human spinal cord.

Nonoperative treatment of osteochondritis dissecans of the humeral capitellum

We examined 24 patients with osteochondritis dissecans of the humeral capitellum to determine the results of nonoperative treatment. The average age of the patients at the initial examination was 13.3 years (range, 11 to 16). All the patients were advised to stop heavy use of the elbow for 6 months. At the last examination, at a mean follow-up period of 5.2 years, 4 patients (17%) had no residual elbow pain, 7 (29%) had pain only with heavy activities, and 13 (54%) had pain with activities of daily living. Final radiographs were obtained for 15 lesions, of which 3 lesions were assessed as healed, 3 as improved, and 9 as not improved. Five of 11 lesions in the early stage and all 4 advanced lesions failed to show radiographic improvement. These results suggest that osteochondritis dissecans of the capitellum has only a slight tendency to heal, and that instability can cause failure of the lesion to heal.

Natural progression of osteochondritis dissecans of the humeral capitellum: initial observations

PURPOSE

To determine the earliest findings, subsequent changes, and natural course of osteochondritis dissecans of the humeral capitellum.

MATERIALS AND METHODS

Among 95 patients with osteochondritis dissecans of the humeral capitellum, 16 (mean age, 12.5 years) were selected for this retrospective study because they seemed to have early osteochondritis dissecans and had been followed up without any surgical treatment for 6 months or more (mean, 3.5 years).

RESULTS

The initial imaging appearances of the 16 patients' lesions were divided into two types: localized subchondral bone flattening without fragments in seven, and nondisplaced fragments in nine. Patients with lesion flattening had younger ages and significantly shorter durations of symptoms, and most had open growth plates. In five of the seven with flattening, new bone formed over the flattened bone, and the fragments united after arm motion reduction. In contrast, patients with nondisplaced fragments at clinical presentation had longer durations of symptoms with continued arm motion, and their nondisplaced fragments failed to unite.

CONCLUSION

The earliest feature of osteochondritis dissecans is subchondral bone flattening, over which new bone subsequently forms. The new bone then can unite with the underlying bone. However, if subjected to repetitive forces over a given time, unstable fragments develop. These fragments, even if not yet displaced, are unable to unite.

A putative mitochondrial ftsZ gene is present in the unicellular primitive red alga Cyanidioschyzon merolae

Two ftsZ homologues were isolated from the unicellular primitive red alga Cyanidioschyzon merolae (CmftsZ1 and CmftsZ2). Phylogenetic analysis revealed that CmftsZ1 is most closely related to the ftsZ genes of alpha-Proteobacteria, suggesting that it is a mitochondrial-type ftsZ gene, whereas CmftsZ2 is most closely related to the ftsZ genes of cyanobacteria, suggesting that it is a plastid-type ftsZ gene. Southern analysis indicates that CmftsZ1 and CmftsZ2 are both single-copy genes located on chromosome XIV in the C. merolae genome. Northern analysis revealed that both CmftsZ1 and CmftsZ2 are transcribed, and accumulate specifically before cell and organelle division. The results of Western analysis suggest that CmFtsZ1 is localized in mitochondria.

Sonographic assessment of osteochondritis dissecans of the humeral capitellum

OBJECTIVE

The purpose of this study was to determine the efficacy of sonography for revealing osteochondritis dissecans of the humeral capitellum.

SUBJECTS AND METHODS

Twenty-seven patients with capitellar osteochondritis dissecans (27 males; range, 11-20 years; mean age, 14 years) underwent radiography and sonography performed with a 7.5-MHz mechanical sector probe. Lesions were assessed as stable or unstable. The sonographic assessment was compared with radiographic assessment in 27 patients, MR assessment obtained in 10, and surgical findings in 15.

RESULTS

Sonographic assessment agreed with radiographic assessment in 23 of the 27 patients, MR assessment in nine of the 10, and surgical findings in 14 of the 15. Sonography revealed that two lesions, which had been underestimated on radiography, were unstable.

CONCLUSION

Sonography facilitates the assessment of capitellar lesions so that treatment can be optimized.

Measurement of testicular volume by ultrasonography

To measure testicular volume accurately, an ultrasonographic method was developed and the results obtained from this compared with those obtained by conventional measurements, namely (1) comparison with testis models, (2) an orchidometer, and (3) measurement of testicular volume by calipers through the scrotal skin. Data from these methods were compared with the actual volume measured at operation by slide calipers placed directly on the testis. The volume obtained by comparison with testis models or with an orchidometer tended to over-estimate the actual volume. The volume measured by slide calipers on scrotal skin was also found to be incorrect. On the other hand, the volume measured by ultrasonography proved to be closer to, and to correlate well with, the actual volume, and was considered to be the best method.

Surgical repair of acute collateral ligament injuries in digits with the Mitek bone suture anchor

Eighteen acute grade III collateral ligament injuries were treated by using the Mitek bone suture anchor. Seven were thumb metacarpophalangeal joint injuries, and eleven were finger proximal interphalangeal joint injuries. Seventeen patients were followed more than 12 months after surgery. All patients were able to use the digits in daily living activities within 5 weeks after surgery, and return to their original work or sports activities within 12 weeks. Pain was completely relieved in 15 patients. Loss of joint motion averaged 7 degrees. In all joints the postoperative lateral stress angle was within 10 degrees of that of the contralateral digit.

Plastid division is driven by a complex mechanism that involves differential transition of the bacterial and eukaryotic division rings

During plastid division, two structures have been detected at the division site in separate analyses. The plastid-dividing ring can be detected by transmission electron microscopy as two (or three) electron-dense rings: an outer ring on the cytosolic face of the outer envelope, occasionally a middle ring in the intermembrane space, and an inner ring on the stromal face of the inner envelope. The FtsZ ring, which plays a central role in bacterial division, also is involved in plastid division and is believed to have descended to plastids from cyanobacterial endosymbiosis. The relationship between the two structures is not known, although there is discussion regarding whether they are identical. Biochemical and immunocytochemical investigations, using synchronized chloroplasts of the red alga Cyanidioschyzon merolae, showed that the plastid FtsZ ring is distinct and separable from the plastid-dividing ring. The FtsZ ring localizes in stroma and faces the inner plastid-dividing ring at the far side from the inner envelope. The FtsZ ring and the inner and outer plastid-dividing rings form in that order before plastid division. The FtsZ ring disappears at the late stage of constriction before dissociation of the plastid-dividing ring, when the constriction is still in progress. Our results suggest that the FtsZ ring;-based system, which originated from a plastid ancestor, cyanobacteria, and the plastid-dividing ring;-based system, which probably originated from host eukaryotic cells, form a complex and are involved in plastid division by distinct modes.

Activation of the mammalian target of rapamycin signalling pathway in epidermal tumours and its correlation with cyclin-dependent kinase 2

BACKGROUND

The enzyme mammalian target of rapamycin (mTOR) integrates many different cellular signals to control cell growth and proliferation, protein synthesis and breakdown, and other processes. Dysregulation of mTOR is implicated in a range of human diseases, including cancers and cardiovascular disorders. To date, there has been no report on the expression of protein kinase B (AKT)/mTOR cell signalling in epidermal tumours.

OBJECTIVES

This study was designed to investigate the activation of the mTOR signalling pathway in epidermal tumours and to correlate this with cyclin-dependent kinase 2 (CDK2) expression.

METHODS

Immunohistological staining was performed with phosphorylated (p-) AKT, p-mTOR, p-4E-binding protein 1 (p-4EBP1), p-ribosomal protein S6 (p-S6), p-p70 ribosomal protein S6 kinase 1 (p-p70S6K1) and CDK2 in 15 cases each of seborrhoeic keratosis, actinic keratosis, keratoacanthoma and Bowen's disease (BD), and 25 cases of squamous cell carcinoma (SCC). Fifteen normal skin (NS) samples served as control.

RESULTS

Among 85 tumours, 40 (47%) were positive for p-AKT, 31 (36%) for p-mTOR, 44 (52%) for p-4EBP1, 38 (45%) for p-S6, and 39 (46%) for p-p70S6K1. CDK2 immunostaining was positive in all cases of SCC and BD, and in 67% of benign tumours. All of these markers were stained much more frequently in malignant tumours than in benign tumours or NS. p-AKT, p-mTOR, p-4EBP1, p-p70S6K1 and p-S6 each showed high correlation with CDK2.

CONCLUSIONS

Constitutive activation of the AKT/mTOR pathway was frequent in epidermal tumours, especially in malignant tumours. Activation was highly correlated with CDK2 expression, suggesting that the AKT/mTOR pathway may induce the malignant transition through CDK2 in epidermal tumours.

Visualization of an FtsZ ring in chloroplasts of Lilium longiflorum leaves

FtsZ is a bacterial division protein which forms a ring at the leading edge of the cell division site. To date, a hypothesis that the plant FtsZ forms the same structure in chloroplast division is proposed, but has not been demonstrated yet. In this study, recombinant LlFtsZ (Lilium longiflorum FtsZ) protein was produced from a previously isolated ftsZ cDNA clone [Mori and Tanaka (2000) Protoplasma 214: 57] and used to raise polyclonal anti-LlFtsZ antibodies in rabbits. In immunoblot analysis with the total protein extracted from L. longiflorum leaves, purified antibodies specifically recognized LlFtsZ whose molecular mass was approximately 43 kDa. This size corresponded to that of the recombinant LlFtsZ protein lacking N-terminal sequence, which suggests that the full-length LlFtsZ translation product has a putative N-terminal signal peptide. Moreover, fluorescent and electron microscopy revealed that the anti-LlFtsZ antibodies recognized ring structures at stromal side of the constriction point of dividing chloroplasts. Here, we show direct evidence that FtsZ ring is involved in chloroplast division.

Developmental failure of the intra-articular ligaments in mice with absence of growth differentiation factor 5

OBJECTIVE

To show the phenotypic characteristics of the knee joints in brachypodism mice (bp mice), which carry a functional null mutation of the growth differentiation factor 5 (GDF5) gene, we investigated the adult and embryonic bp mice.

METHOD

Radiographic and macroscopic examinations of the knee joint of adult bp mice were performed. A histological examination of the knee joint of bp mice from E12.5 to E18.5 was also performed.

RESULTS

Radiographic and macroscopic examinations of the adult bp mice showed anterior dislocation, hypoplastic condyles, and absence of the intra-articular ligaments. Safranin O staining of knee joints of the embryonic bp mice showed severe hypoplasty of the chondroepiphyses and intra-articular ligaments at E16.5. There was no difference in the number and location of 5-bromo-2'-deoxyuridine (BrdU)-positive cells between wild-type and bp mice through E12.5 to E14.5. A terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) study showed excessive cell death of mesenchymal cells of the future knee joint in bp mice at E12.5 and E13.5.

CONCLUSION

bp mice exhibit developmental failure of the condyles and intra-articular ligament of the knee joints.

Increased expression of an epidermal stem cell marker, cytokeratin 19, in cutaneous squamous cell carcinoma

BACKGROUND

Cytokeratin 19 (CK19) has been considered to be a putative marker for epidermal stem cells in the hair follicle bulge. Cumulative reports have shown that epidermal stem cells play an important role in skin carcinogenesis. However, to date there has been no report on the clinical alteration of the stem cells in squamous cell carcinoma (SCC).

OBJECTIVES

To investigate alteration of the stem cells and proliferating cells and to assess their relationship and potential contribution to SCC.

METHODS

Thirty paraffin-embedded neoplastic skin lesions, consisting of 10 cases each of actinic keratosis (AK), Bowen disease (BD) and SCC, were examined immunohistologically for CK19 and Ki-67.

RESULTS

Positive reactivity for CK19 was seen in 30% of AK, 50% of BD and 80% of SCC lesions. There was significantly higher expression levels of CK19 in SCC than in AK and BD (P < 0.05). In addition, BD lesions harboured a significantly higher number of CK19-positive cells than did AK lesions (P < 0.05). There were significant differences in Ki-67 labelling indices between AK and BD and between AK and SCC (P < 0.001), but not between BD and SCC (P > 0.05). Furthermore, a serial section comparison study showed that there was a minor population of cells co-expressing CK19 and Ki-67 in a subset of the tumour cells of SCC samples. The percentage of CK19+ cells significantly correlated with that of Ki67+ cells in all examined neoplastic skin lesions.

CONCLUSIONS

These results suggest that CK19 expression may be associated with the retention of stem cell characteristics or a state that is uncommitted to terminal squamous differentiation.

Novel filaments 5 nm in diameter constitute the cytosolic ring of the plastid division apparatus

The plastid division apparatus (called the plastid-dividing ring) has been detected in several plant and algal species at the constricted region of plastids by transmission electron microscopy. The apparatus is composed of two or three rings: an outer ring in the cytosol, an inner ring in the stroma, and a middle ring in the intermembrane space. The components of these rings are not clear. FtsZ, which forms the bacterial cytokinetic ring, has been proposed as a component of both the inner and outer rings. Here, we present the ultrastructure of the outer ring at high resolution. To visualize the outer ring by negative staining, we isolated dividing chloroplasts from a synchronized culture of a red alga, Cyanidioschyzon merolae, and lysed them with nonionic detergent Nonidet P-40. Nonidet P-40 extracted primarily stroma, thylakoids, and the inner and middle rings, leaving the envelope and outer ring largely intact. Negative staining revealed that the outer ring consists of a bundle of 5-nm filaments in which globular proteins are spaced 4.8 nm apart. Immunoblotting using an FtsZ-specific antibody failed to show immunoreactivity in the fraction containing the filament. Moreover, the filament structure and properties are unlike those of known cytoskeletal filaments. The bundle of filaments forms a very rigid structure and does not disassemble in 2 M urea. We also identified a dividing phase-specific 56-kD protein of chloroplasts as a candidate component of the ring. Our results suggest that the main architecture of the outer ring did not descend from cyanobacteria during the course of endosymbiosis but was added by the host cell early in plant evolution.

Plastid division is driven by a complex mechanism that involves differential transition of the bacterial and eukaryotic division rings

During plastid division, two structures have been detected at the division site in separate analyses. The plastid-dividing ring can be detected by transmission electron microscopy as two (or three) electron-dense rings: an outer ring on the cytosolic face of the outer envelope, occasionally a middle ring in the intermembrane space, and an inner ring on the stromal face of the inner envelope. The FtsZ ring, which plays a central role in bacterial division, also is involved in plastid division and is believed to have descended to plastids from cyanobacterial endosymbiosis. The relationship between the two structures is not known, although there is discussion regarding whether they are identical. Biochemical and immunocytochemical investigations, using synchronized chloroplasts of the red alga Cyanidioschyzon merolae, showed that the plastid FtsZ ring is distinct and separable from the plastid-dividing ring. The FtsZ ring localizes in stroma and faces the inner plastid-dividing ring at the far side from the inner envelope. The FtsZ ring and the inner and outer plastid-dividing rings form in that order before plastid division. The FtsZ ring disappears at the late stage of constriction before dissociation of the plastid-dividing ring, when the constriction is still in progress. Our results suggest that the FtsZ ring;-based system, which originated from a plastid ancestor, cyanobacteria, and the plastid-dividing ring;-based system, which probably originated from host eukaryotic cells, form a complex and are involved in plastid division by distinct modes.

Synthesis of Escherichia coli heat-stable enterotoxin STp as a pre-pro form and role of the pro sequence in secretion

Escherichia coli heat-stable enterotoxin STp is presumed from its DNA sequence to be synthesized in vivo as a 72-amino-acid residue precursor that is cleaved to generate mature STp consisting of the 18 carboxy-terminal amino acid residues. There are two methionine residues in the inferred STp sequence in addition to the methionine residue at position 1. In order to confirm production of the STp 72-amino-acid residue precursor, we substituted the additional methionine residues by oligonucleotide-directed site-specific mutagenesis. Since these substitutions did not cause a significant change in STp production, it can be concluded that STp is normally synthesized as the 72-amino-acid residue precursor. The length of the STp precursor indicated the existence of a pro sequence between the signal peptide and the mature protein. In order to identify the pro sequence and determine its role in protein secretion, deletion and fusion proteins were made. A deletion mutant in which the gene fragment encoding amino acid residues 22 to 53 of STp was removed was made. STp activity was found in the culture supernatant of cells. Amino acid sequence analysis of the purified STp deletion mutant revealed that the pro sequence encompasses amino acid residues 20 to 54. A hybrid protein consisting of STp amino acids 1 to 53 fused in frame from residue 53 to nuclease A was not secreted into the culture supernatant. These results indicate that the pro sequence does not function to guide periplasmic protein into the extracellular milieu.

Second fracture of the distal humerus after varus malunion of a supracondylar fracture in children

Nine children sustained a second fracture of the distal humerus after union of an ipsilateral supracondylar fracture which had healed with cubitus varus. There were eight boys and one girl with a mean age of five years (1 to 8) at the time of the second fracture which occurred at a mean of 1.5 years after the first. In all patients, the second fracture was an epiphyseal injury of the distal humerus, either associated with a fracture of the lateral metaphysis below the site of the previous supracondylar fracture, or a fracture-separation of the entire distal humeral epiphysis. This suggests that the physis and epiphysis tend to be more subject to injury than the metaphysis of the distal humerus in children who have had a previous supracondylar fracture with varus malunion.

Relationship between grade of varicocele and the response to varicocelectomy

BACKGROUND

Although several studies indicate that larger varicoceles are associated with greater impairment of spermatogenesis, others suggest that the response to surgery is independent of varicocele size. In order to elucidate these seeming contradictions, correlations between the preoperative evaluation of varicoceles and improvement in semen quality after varicocelectomy were investigated.

METHODS

Forty men with left unilateral varicocele, followed for at least 6 months after varicocelectomy, were included in this study. The relationships between the grade of varicocele by palpation, Doppler examination, ultrasound, or scintigraphy were correlated with a postoperative improvement in sperm density or sperm motility.

RESULTS

Greater improvement in sperm density was observed in the patients with a large varicocele graded by palpation or measured by ultrasound, and greater improvement in sperm motility was observed in the patients with high uptake of radioactivity in the left side by scrotal scintigraphy.

CONCLUSION

An improvement in semen quality after varicocelectomy is greater in patients with a large varicocele than in the patients with a small one. The significance of surgical repair of a small varicocele should be reconsidered.

Bone-peg grafting for osteochondritis dissecans of the humeral capitellum

PURPOSE

To review the outcome of bone-peg grafting for osteochondritis dissecans (OCD) grade II lesions of the humeral capitellum.

METHODS

Records of 10 male adolescent baseball players aged 10 to 15 (mean, 12.3) years who underwent bone-peg grafting for OCD grade II lesions of the humeral capitellum of the dominant arm were reviewed. The mean time from symptom onset to presentation was 11 (range, 1-36) months. The mean duration of conservative treatment was 5 (range, 1-25) months. The mean time from symptom onset to surgery was 17 (range, 3-39) months; it was >6 months in 6 patients. The mean size of the lesions was 13x14 mm. Patients were assessed for elbow pain, range of elbow and forearm motion, Timmerman- Andrews elbow score, return to sports activity level, and radiographic evidence of healing, osteoarthritic changes, and radial head hypertrophy.

RESULTS

The mean follow-up period was 25 (range, 10-52) months. Postoperatively, elbow pain was absent in 6, mild in 2, and moderate in 2 patients. The mean range of elbow motion changed from 136º to 139° (p=0.80). The mean Timmerman-Andrews elbow score improved from 163 to 189 (p=0.014); it was excellent in 7, good in 2, and fair in one patient. The mean extent of lesion healing was 71% (range, 33-100%). Five patients achieved complete healing after a mean of 5.2 (range, 5-6) months and returned to sports at a competitive level. The other 5 achieved partial healing of 33 to 56% (mean, 41%) that occurred laterally but not medially. Two of them returned to sports at a competitive level: one changed the throwing side and another had radial head hypertrophy. The remaining 3 underwent arthroscopic debridement of the unhealed lesion at 5, 10, and 15 months. One patient developed secondary osteoarthritis and further underwent costal osteochondral autografting 10 months later. None of the 5 patients with partial healing versus 4 of the 5 patients with complete healing underwent surgery within 6 months of symptom onset. All 3 patients with a dot at the interface versus 2 of the 6 patients with a line at the interface between the fragment and the lesion on MRI had complete healing.

CONCLUSION

Bone-peg grafting is a viable option for OCD grade II lesions of the humeral capitellum when performed within 6 months of symptom onset and when the interface between the fragment and the lesion appears as a dot (rather than a line) on MRI.