Standardized ejection fraction as a parameter of overall ventricular pump function

To evaluate the pump function of the ventricle, a parameter which (i) incorporates systolic and diastolic function and (ii) separates the heart from preload and afterload is needed. This study utilized ejection fraction (EF), calculated from the end-systolic (ES) and end-diastolic (ED) pressure-volume relationship (PVR) using an arbitrary set of loading conditions. Ten isolated canine hearts with a balloon placed inside the left ventricle were used to determine the ESPVR and EDPVR. An end-diastolic volume (EDV) at a pressure of 15 mmHg and an end-systolic volume (ESV) at 70 mmHg were obtained from the EDPVR and ESPVR, respectively. EF was calculated as (EDV-ESV)/EDV. With low-dose (8 microg/min) and high-dose (40 microg/min) dobutamine infusion, the EF increased from 0.25+/-0.16 to 0.33+/-0.13 and 0.57+/-0.08 (p<0.01), respectively, in conjunction with increases in end-systolic elastance from 3.11+/-0.83 to 3.48+/-1.08 and 5.38+/-1.91 mmHg/ml (p<0.01). It was thus concluded that because the estimation of EF separates the heart from preload and afterload, this method may facilitate comparing overall pump function of hearts beating under different loading conditions.

Interaction of albumin mRNA with proteins from rat liver with CCl(4)-induced injury

Acute phase responses to intragastric administration of a single dose of CCl(4) were examined with albumin mRNA turnover as a marker. Based on the combination of the changes in stability of albumin mRNA and activity of transcription of its gene, the entire course of liver injury was classified into three stages, the first stage for aggravation of injury until 9 h, the second from 9 to 24 h, and the third for repair of injury or regeneration of liver after 48 h. Liver S100 fractions from normal and CCl(4)-treated rats contained, in total, 11 polypeptides cross-linked with part of albumin mRNA, although they did not appear to be specific to this mRNA. Their profiles were altered together with the changes in stability of albumin mRNA in different stages. These findings suggest that the polypeptides with distinct properties play roles in physiologically significant processes involved in utilization and turnover of albumin mRNA, apparently altering its stability.

CD44 expression in soft tissue sarcomas

Recent studies have shown that expression of alternatively splicing variants of CD44 is correlated with prognosis for several kinds of malignant tumors. However, little is known about the expression of CD44 standard and variant isoforms in soft tissue sarcomas. In this study 47 cases of soft tissue sarcoma [18 malignant fibrous histiocytomas (MFHs), 13 synovial sarcomas (SSs), 7 malignant schwannomas (MSs), and 9 liposarcomas (LSs)] were examined immunohistochemically. The monoclonal antibodies to the standard form of CD44 (CD44H) and variant exons of CD44v3, 4, 5, 6, 7, 9, and v10 were used. We analyzed the membranous expression pattern of CD44H and CD44 variant exons and assessed the relation between expression of CD44s and metastasis-free survival rates (MFSR) of patients with soft tissue sarcoma. A few sarcomas expressed CD44v3 (2/47) and v7 (2/47), but none of the sarcomas expressed CD44v10. CD44v4 (5/47), v5 (4/47), v6 (10/47), and v9 (9/47) are relatively common types of variant isoforms in soft tissue sarcomas. Expression of CD44v6 is more frequently detected in high-grade than in low-grade tumors. CD44v6 or CD44v9 expression was correlated with metastasis-free survival of patients with soft tissue sarcomas.

Mutagenicity of bovine lactoferrin in reverse mutation test

The mutagenicity of bovine lactoferrin, which is an iron-binding glycoprotein in milk, was evaluated by the Ames mutagenicity test. A total of 5 test strains including 3 base-pair substitution-type strains, Salmonella typhimurium TA100, TA1535 and Escherichia coli WP2uvrA, and 2 frameshift-type strains, TA98 and TA1537, were used in the test. The test was performed by both the direct method and the metabolic activation method with preincubation applied in each instance. The concentration range of the test solution was 0.16 to 5.00 mg/100 microliters (plate). Results of the test revealed that the number of revertant colonies at each concentration of the test solutions was less than 1.4 times that of the control group. In the test system used, bovine lactoferrin did not exhibit mutagenicity.

Recurrent pulmonary adenoid cystic carcinoma presenting as a cardiac tumor

A 58-year-old patient is presented who had a pulmonary adenoid cystic carcinoma which recurred 10 years after sleeve left pneumonectomy. The patient developed acute heart failure because the lesion obstructed blood flow by compressing the left atrium. Transesophageal echocardiography and magnetic resonance imaging demonstrated a solid mass arising from the pericardium which displaced the posterior wall of the left atrium. The mass was resected. Postoperative radiation was not performed.

Strong association of SYT-SSX fusion type and morphologic epithelial differentiation in synovial sarcoma

Synovial sarcoma is characterized by a specific recurrent translocation t(X; 18), resulting in either the SYT-SSX1 or SYT-SSX2 gene fusion. Because this is the primary genetic alteration in these tumors, we sought to identify the impact of molecular heterogeneity of the t(X;18) on cell proliferation, apoptosis, and epithelial differentiation in synovial sarcoma. Seventy-three patients with synovial sarcoma (18 biphasic, 55 monophasic) were selected on the basis of availability of tumor material for molecular and immunohistochemical analysis. Tumors were classified as biphasic on the basis of morphologic glandular differentiation. SYT-SSX fusion transcripts were examined by reverse transcriptase polymerase chain reaction using tumor RNA extracted from frozen or paraffin-embedded tissue. Cell proliferation was assessed immunohistochemically by the Ki-67 labeling index. Apoptosis was analyzed immunohistochemically with BAX and BCL2 antibodies and by the TUNEL method. Immunohistochemical evidence of epithelial differentiation was assessed using antibodies to cytokeratins and epithelial membrane antigen. Approximately two thirds of the tumors had an SYT-SSX1 and one third had an SYT-SSX2 fusion transcript. There was a strong association between SYT-SSX fusion type and histologic subtype. All biphasic synovial sarcomas had the SYT-SSX1 fusion, whereas all tumors with SYT-SSX2 were of monophasic morphology. There was, however, no association between SYT-SSX fusion type and expression of cytokeratins and epithelial membrane antigen among monophasic tumors. Tumors with SYT-SSX2 had a significantly higher mean and median Ki-67 labeling index than those with SYT-SSX1, but a comparison of Ki-67 according to fusion type, histologic type, and sample source suggested that the main determinants of proliferation rate were the latter two factors. Specifically, monophasic tumors and metastatic tumors showed significantly higher Ki-67 scores. Apoptosis (by TUNEL) was rarely observed, consistent with prominent expression of the anti-apoptotic protein BCL2 in almost all cases. TUNEL, BCL2, and BAX results did not correlate with SYT-SSX fusion type. These data confirm the strong association of SYT-SSX fusion transcript type with morphologic but not immunophenotypic epithelial differentiation in synovial sarcoma.

Inhibitory effect of TMK-688 on late asthmatic responses as well as T-cell and eosinophilic infiltration in guinea pigs with asthmatic reactions

The effects of an oral anti-allergic agent, TMK-688, which inhibits 5-lipoxygenase, at doses of 3.2 and 10 mg/kg were studied in guinea pigs with dual-phase asthmatic response. We previously observed that pretreatment with TMK-688 inhibited the late asthmatic response (LAR) induced by ovalbumin inhalation exposure. The present study focused on the effect of TMK-688 on infiltration by T-cells and eosinophils. TMK-688 inhibited both T-cell and eosinophilic infiltration. These findings suggest that TMK-688 is effective in inhibiting infiltration of T-cells and eosinophilic chemotaxis, and thereby suppresses LAR.

Mapping of epitopes and structural analysis of antigenic sites in the nucleoprotein of rabies virus

Linear epitopes on the rabies virus nucleoprotein (N) recognized by six MAbs raised against antigenic sites I (MAbs 6-4, 12-2 and 13-27) and IV (MAbs 6-9, 7-12 and 8-1) were investigated. Based on our previous studies on sites I and IV, 24 consecutively overlapping octapeptides and N- and C-terminal-deleted mutant N proteins were prepared. Results showed that all three site I epitopes studied and two site IV epitopes (for MAbs 8-1 and 6-9) mapped to aa 358-367, and that the other site IV epitope of MAb 7-12 mapped to aa 375-383. Tests using chimeric and truncated proteins showed that MAb 8-1 also requires the N-terminal sequence of the N protein to recognize its binding region more efficiently. Immunofluorescence studies demonstrated that all three site I-specific MAbs and one site IV-specific MAb (7-12) stained the N antigen that was diffusely distributed in the whole cytoplasm; the other two site IV-specific MAbs (6-9 and 8-1) detected only the N antigen in the cytoplasmic inclusion bodies (CIB). An antigenic site II-specific MAb (6-17) also detected CIB-associated N antigen alone. Furthermore, the level of diffuse N antigens decreased after treatment of infected cells with cycloheximide. These results suggest that epitopes at site I are expressed on the immature form of the N protein, but epitope structures of site IV MAbs 6-9 and 8-1 are created and/or exposed only after maturation of the N protein.

Electrophoretic and serologic characterization of 56 kDa antigen (M56) with autologous serum derived from a chondrosarcoma patient: a shared antigen of immunoresponses in cancer and autoimmune diseases

We investigated whether antibodies specific to autologous cancer cells are produced in the peripheral blood of patients with chondrosarcoma. There have been few reports on the investigation of the immune responses, such as autologous antibody production, to chondrosarcoma. Here, tumor-associated antigens were separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and detected by immunoenzymatic amplification. A 56 kDa molecule (M56) was detected in the serum from patients' peripheral blood. M56 is ubiquitously expressed in various kinds of tissue-derived cells. However, the molecule seemed to be retained mostly in the cytosolic compartment of lymphoid cells, while it was expressed on the cell surface of nonlymphoid cancer cells. Furthermore, the antibodies reactive to the 56 kDa molecule were frequently observed in sera derived from patients with other cancers and autoimmune diseases as compared to the sera from healthy control donors, suggesting that M56 is a common target molecule of immune responses in patients with various cancers and autoimmune diseases.

Native heart complications after heterotopic heart transplantation: insight into the potential risk of left ventricular assist device

BACKGROUND

In heterotopic heart transplantation, the donor heart is connected parallel to the recipient's diseased heart. Recipients continue to have risks, such as arrhythmia, thromboembolism, valvular heart disease, and ischemic heart disease which can develop in the native heart. It may serve as a clinical model to study long-term pathophysiologic processes in the native heart of patients with a left ventricular assist device.

METHOD

We analyzed the prevalence of long-term complications related to the native heart in the heterotopic heart transplant and attempted to gain insight into the potential risk to a native heart after receiving a left ventricular assist device.

RESULTS

Between December 1984 and December 1994, 16 patients (13 men, 3 women, ranging in age from 37 to 60 years) underwent heterotopic heart transplant at the University of Pittsburgh. The 1- and 5-year survival rate after the transplant was 81% and 44%, respectively. Actuarial freedom from complications related to the native heart after 1 year and 4 years was ventricular arrhythmia: 85%, 75%; ischemic disease: 85%, 64%; valvular disease: 100%, 88%; and thromboembolism: 85%, 58%. Of these complications, thromboembolism was not considered in determining actuarial freedom from complications because thromboembolism should be regarded as a device-related complication rather than as a native-heart-related complication for left ventricular assist device recipients. Consequently, actuarial freedom from all complications excluding thromboembolism was 70% after 1 year and 50% after 4 years. In addition, the hazard function curve remains constant up to 80 months after the operation without significant differences among the yearly ratios.

CONCLUSIONS

This analysis suggests that cautious observation of the native heart's long-term performance is necessary for the left ventricular assist device recipient.

Expression of CD44 variants in osteosarcoma

The standard form of CD44 (CD44H) is a transmembranous glycoprotein, widely distributed on a variety of human lymphoid cells, epithelial cells and tumours. CD44 has many variant forms, which are generated by alternative splicing. In recent years, CD44 has been reported to be related to the degree of tumour differentiation, tumour cell invasion, and metastasis. We investigated 44 tumour specimens in 39 patients with osteosarcoma immunochemically to analyse the expression of CD44 standard (CD44H) and variant exon-encoded gene products (CD44v3, v4, v5, v6, v7, v9, and v10). Furthermore, the relationship between CD44 expression and the clinical outcome of patients with osteosarcoma was analysed. Membrane accentuation and exclusive cytoplasmic reactivity were analysed as separate staining patterns. Tumour cells and some multinucleated giant cells were markedly stained. CD44H, v3, v4, v5, v6, v7, v9, and v10 were expressed in 85%, 49%, 54%, 59%, 46%, 5%, 28%, and 10% of the specimens respectively. The cumulative 5-year metastasis-free survival was 58% in CD44v6-negative cases and 24% in CD44v6-positive cases (P=0.046). However, the cumulative 5-year metastasis-free survival was not significantly different between cases positive and negative for other variants of CD44. Multivariate analysis (Cox proportional-hazard model) with CD44v6 expression (positive or negative), chemotherapy (intensive or non-intensive), tumour site (proximal or distal), and age (at least 30 years or less than 30 years) showed that expression of CD44v6 and chemotherapy were important prognostic factors in patients with osteosarcoma. Overexpression of CD44 isoforms containing variant v6 is correlated with poor prognosis in patients with osteosarcoma.

Nucleocapsid formation and/or subsequent conformational change of rabies virus nucleoprotein (N) is a prerequisite step for acquiring the phosphatase-sensitive epitope of monoclonal antibody 5-2-26

We investigated the antigenic maturation of rabies virus N protein, for which we used some conformational epitope-specific monoclonal antibodies (MAbs) and an MAb (5-2-26) against a phosphorylation-dependent linear epitope. Infected cells were lysed with a deoxycholate-free lysis buffer and separated by ultracentrifugation into the soluble top and the nucleocapsid fractions. None of the study MAbs recognized N proteins in the top fraction, whereas nucleocapsid-associated N proteins were recognized by all of the MAbs. Immunoprecipitation with polyclonal anti-N antibodies coprecipitated the P proteins from the top fraction, indicating that soluble N proteins are mostly associated with the P protein. The N proteins dissociated from both the N-P complex and nucleocapsids were recognized by none of the study MAbs, whereas the MAb 5-2-6 recognized the SDS-denatured N proteins of the nucleocapsid but not of the top fraction. In addition, the phosphorylation-deficient mutant N proteins were shown to be similarly accumulated as the wild-type N proteins into the viral inclusion bodies, defined as the virus-specific structures composed of viral nucleocapsids, that are produced in the cytoplasm of the infected cells. Based on these results, we believe that newly synthesized N proteins are not immediately phosphorylated at serine-389 (a common phosphorylation site) but are first associated with the P protein. After being used for encapsidation of the viral RNA, the N proteins undergo conformational changes, whereby epitopes for the conformation-specific MAbs are formed and become phosphorylated at serine-389.

Double-layered membrane vesicles released from mammalian cells infected with Sendai virus expressing the matrix protein of vesicular stomatitis virus

The matrix (M) protein of vesicular stomatitis virus (VSV) was reported to form vesicles on the cell surface and subsequently to be released into the cultured medium when expressed from cDNA by virus vectors. To further investigate VSV M activity, we generated a recombinant Sendai virus (SeV) expressing the VSV M protein (SeV-M(VSV)). When cells were infected with SeV-M(VSV), VSV M was found abundantly in the culture medium. Electron microscopy demonstrated the budding of two-membraned vesicles (>/= 0.8 microm in diameter) from the infected cells. The outer membrane of the vesicle was derived from the plasma membrane and the inner one possibly derived from the membrane of an intracellular vesicle. Immuno-gold labeling showed that VSV M was exclusively located in a double-layered region. The released membranes were divided into three parts: the VSV M vesicles with SeV F and HN glycoproteins, SeV particles, and vesicles associated with the cytosolic components. The last abundantly contained phosphorylated SeV matrix (M) protein, which is not released in a usual SeV infection. Furthermore the VSV M protein expressed without using a virus vector was efficiently released into the culture medium. These results suggest that the VSV M protein has a budding activity per se and that SeV proteins are passively involved in the release of VSV M.

[A case report of total aortic reconstruction and choice of staged operation in Marfan syndrome]

A 37-year-old man with Marfan syndrome underwent four operations for extensive cardiovascular disease. He was diagnosed as having AAE, AR and DeBakey type I aortic dissection. First, Bentall operation using Piehler procedure and total aortic arch replacement using retrograde cerebral perfusion and profound hypothermia at 18 degrees C were performed on May 11, 1994. Second, repair of leakage of the right coronary artery anastomosis and grafting for the descending thoracic aortic aneurysm were performed on December 3, 1994. Y-type grafting for the AAA was performed on December 21, 1996. Last, grafting for TAAA was performed under hypothermia at a rectal temperature of 20 degrees C on November 17, 1997. This surgical strategy of staged operation for extensive cardiovascular disease in Marfan syndrome is an effective method. Regular follow-up by CT is necessary for deciding the time and method of reoperation.

Insertion of the patella tendon after prosthetic replacement of the proximal tibia

We describe the technique and the results of a method to reconstruct the patellar tendon insertion to a tumor prosthesis by wrapping an artificial mesh around the prosthesis, followed by suturing the patellar tendon and a gastrocnemius flap to the mesh.

Imaging assessment of the responses of osteosarcoma patients to preoperative chemotherapy: angiography compared with thallium-201 scintigraphy

BACKGROUND

Assessment of the responses of osteosarcoma patients to preoperative chemotherapy is of clinical importance. The purpose of this study was to estimate the accuracy of angiography and thallium-201 scintigraphy, compared with histology, in assessing the responses of patients with osteosarcoma to preoperative chemotherapy.

METHODS

Nineteen patients with osteosarcoma who were diagnosed between 1992 and 1997 were studied. The findings of angiography and thallium-201 scintigraphy before and after preoperative chemotherapy were compared with the percentage of necrosis of tumor cells and the response grade as determined histologically. Quantitative analysis of the isotopic uptake by thallium-201 scintigraphy before and after chemotherapy, defined as the alteration ratio, was correlated with the percentage of tumor necrosis.

RESULTS

Angiography yielded a sensitivity of 88%, a specificity of 73%, and a predictive accuracy of positive test of 70%, whereas thallium-201 scintigraphy achieved 88%, 100%, and 100%, respectively. Both angiographic and scintigraphic assessment showed a significant correlation with response grade as determined histologically (P < 0.05 and P < 0.0003, respectively). The alteration ratio of thallium-201 scintigraphy showed a strong, highly significant correlation with the percentage of tumor necrosis (P < 0.0001).

CONCLUSIONS

A change in the tumor uptake of thallium-201 scintigraphy after preoperative chemotherapy can predict the tumor necrosis in osteosarcoma precisely. Thallium scintigraphy is a noninvasive technique and seems to be more useful than angiography in assessing the response of osteosarcoma to preoperative chemotherapy.

Reconstruction of the hip abductors after resection of the proximal femur

Three patients with malignant bone tumors of the proximal femur underwent implantation of an endoprosthesis with reconstruction of the joint capsule and hip abductors using artificial mesh.

Prolonged preservation of the blood-perfused canine heart with glycolysis-promoting solution

BACKGROUND

Prolonged ischemia and inadequate myocardial preservation remain significant perioperative risk factors in cardiac transplantation. Long-term preservation techniques that have been effective in small rodent hearts have not been as effective in larger animal models or in clinical studies. We developed a cardioplegia solution formulated to promote high-energy phosphate production from glycolysis and determined its efficacy in a blood perfused canine heart model subjected to 24 hours of ischemia.

METHODS

Hearts harvested from adult dogs (n = 6 per group) were flushed with a histidine-buffered cardioplegia solution containing glucose or University of Wisconsin solution. The hearts were maintained at 4 degrees C for 24 hours then reperfused with autologous blood. After reperfusion, left ventricular pressures were measured with an intracavitary balloon at varying balloon volumes and compared with control nonischemic hearts. Predicted stroke volume and ejection fraction were calculated at an end-systolic pressure of 70 mm Hg and end-diastolic pressure of 15 mm Hg.

RESULTS

Developed pressure was better preserved in the hearts that received histidine-buffered solution (93+/-9 versus 38+/-7 mm Hg, p<0.05), along with a higher end-diastolic volume at 15 mm Hg (31+/-3 versus 22+/-2 mL histidine-buffered versus University of Wisconsin solutions, respectively, p<0.05). Stroke volume and ejection fraction were also higher in the histidine group (17+/-2.5 versus 2.3+/-1.2 mL and 50%+/-3.5% versus 9% +/-4.5%, respectively) in the presence of dobutamine.

CONCLUSIONS

The highly buffered glycolysis-promoting cardioplegia solution provided effective preservation of the blood perfused canine heart with superior recovery of pump performance after 24 hours of hypothermic ischemia compared with University of Wisconsin solution in this model.

Association of a cellular 21-kDa transmembrane protein (VAP21) with enveloped viruses

We reported previously that the rabies virions contained a 21-kDa cellular transmembrane protein (referred to as VAP21) as a minor component (Sagara, J. et al, Microbiol. Immunol. 41(12): 947-955, 1997). In this study, we further examined the possible interactions of VAP21 with other enveloped viruses, including the vesicular stomatitis virus (VSV; negative-stranded RNA virus), Sindbis virus (positive-stranded RNA virus) and herpes simplex virus type 1 (HSV-1; double-stranded DNA virus). An immunoblot analysis demonstrated that all of these enveloped viruses contained VAP21 in the virion as a minor component. Immunoprecipitation studies suggested that VAP21 was associated with certain viral proteins in the cell, such as the matrix (M) protein of VSV, a capsid protein of Sindbis virus, and at least a capsid protein (VP5) of HSV-1. The association was disrupted by treatment with 0.5% sodium dodecyl sulfate, but resistant to the treatment with 1% NP-40 plus 1% deoxycholate. These results suggest that: 1) VAP21 is not primarily associated with the viral transmembrane glycoprotein but rather with the internal viral protein, and, 2) this association would cause the efficient incorporation of VAP21 into the virion.

Evaluation of release surgery for idiopathic carpal tunnel syndrome: endoscopic versus open method

To evaluate the usefulness of endoscopic carpal tunnel release (ECTR) on patients with idiopathic carpal tunnel syndrome, multiple aspects of the results of 44 hands (42 patients) treated by ECTR and 40 hands (40 patients) treated by open carpal tunnel release (OCTR) were compared. Results of ECTR were compared with those of OCTR to study not only recovery rate and surgical safety but also cost-effectiveness. Although ECTR was much less invasive than OCTR, recovery of median nerve palsy in the ECTR group was not as good as that in the OCTR group one month after the surgery. Three months after surgery, the palsy of patients treated by ECTR had improved to almost the same extent as in those treated by OCTR. There were no major surgical complications in both ECTR and OCTR groups. The cost and time needed for ECTR treatment was 1/3 of those needed for OCTR. ECTR reduced both cost and treatment time, which is beneficial for both doctors and patients.

A case of bilateral eosinophilic granuloma in the temporal bone

We present a case of bilateral eosinophilic granuloma in the temporal bone in a 47-year-old woman, who visited our hospital with a headache and a feeling of occlusion in her left ear. Her left tympanic membrane was slightly turbid and pure tone audiometry revealed mild left sensorineural deafness. CT disclosed a shadow of soft tissue in the left mastoid antrum and mastoid cells, which was indicative of marked destruction of the bone. Because MRI findings led us to suspect otitis media cholesteatoma, a mastoidectomy was performed. The mastoid antrum and mastoid cells were filled with easily bleeding granulation, and there was a wide range of bone deficit in the posterior cranial fossa. Histopathologically, the granulation tissue was an eosinophilic granuloma. Her postoperative clinical progress was good and she was discharged. However 2 months after discharge, she had a feeling of occlusion in the right ear and CT revealed a shadow in the right mastoid antrum and cells. Therefore, right tympanoplasty was performed and the same findings as in the left ear were obtained. A histopathological diagnosis of eosinophilic granuloma was made again. To date, there has been no recurrence.

Intracellular behavior of rabies virus matrix protein (M) is determined by the viral glycoprotein (G)

To investigate the nature and intracellular behavior of the matrix (M) protein of an avirulent strain (HEP-Flury) of rabies virus, we cloned and sequenced the cDNA of the protein. Using expression vectors pZIP-NeoSV(X)1 and pCDM8, the cDNA was transfected to animal cells (BHK-21 and COS-7) with or without coexpression of viral glycoprotein (G). When M protein alone was expressed in the cells, it displayed homogeneous distribution in the whole cell including the nucleus. In contrast, coexpression with G protein resulted in the abolishment of nuclear distribution of M antigen, and both of the antigens displayed a colocalized distribution in the cell, especially at the cellular membrane as seen in the virus-infected cells, while the distribution of G antigen was not affected by coexpressed M antigen. Immunoprecipitation studies revealed that M protein was coprecipitated with G protein by anti-G antibody, and vice versa, although cross-linking with dithiobis(succinimidyl propionate) was necessary for coprecipitation because of their easier dissociation in the presence of sodium deoxycholate. These results suggest that M protein intimately associates with G protein, which may affect or regulate the behavior (e.g., intracellular localization) of M protein. Studies with deletion mutants of M protein indicate that an internal region around the amino acids from 115 to 151 is essential for the M protein to preserve its binding ability to G protein.

Newly identified Chinese hamster ovary cell mutants defective in peroxisome assembly represent complementation group A of human peroxisome biogenesis disorders and one novel group in mammals

We isolated peroxisome biogenesis-defective mutants from rat PEX2-transformed Chinese hamster ovary (CHO) cells, using the 9-(1'-pyrene)nonanol/ultraviolet method. A total of 18 mutant cell clones showing cytosolic localization of catalase were isolated. By complementation group (CG) analysis by means of PEX cDNA transfection and cell fusion, cell mutants, ZP124 and ZP126, were found to belong to two novel CGs of CHO mutants. Mutants, ZP135 and ZP167, were also classified to the same CG as ZP124. Further cell fusion analysis using 12 CGs fibroblasts from patients with peroxisome deficiency disorders such as Zellweger syndrome revealed that ZP124 belonged to human CG-A, the same group as CG-VIII in the United States. ZP126 could not be classified to any of human and CHO CGs. These mutants also showed typical peroxisome assembly-defective phenotypes such as severe loss of catalase latency and impaired biogenesis of peroxisomal enzymes. Collectively, ZP124 represents CG-A, and ZP126 is in a newly identified CG distinct from the 14 mammalian CGs previously characterized.

Isolation and characterization of novel peroxisome biogenesis-defective Chinese hamster ovary cell mutants using green fluorescent protein

We developed an improved method for isolation of peroxisome biogenesis-defective somatic animal cell mutants, using a combination of green fluorescent protein (GFP) expression and the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) selection method. We used TKaG1 and TKaG2 cells, the wild-type Chinese hamster ovary (CHO) cells, CHO-K1, that had been stably transfected with cDNAs each encoding rat Pex2p as well as GFP tagged at the C-terminus with peroxisome targeting signal type 1 (PTS1) or N-terminally PTS2-tagged GFP. P9OH/UV-resistant cell colonies were examined for intracellular location of GFP on unfixed cells, by fluorescence microscopy. Seven each of the mutant cell clones isolated from TKaG1 and TKaG2 showed cytosolic GFP-PTS1 and PTS2-GFP, respectively, indicating the defect in peroxisome assembly. By transfection of PEX2, PEX5, PEX6, and PEX12 cDNAs and cell fusion analysis between the CHO cell mutants, five different complementation groups (CGs) were identified. Two mutant clones, ZPG207 and ZPG208, belonged to novel CGs. Further CG analysis using fibroblasts from patients with peroxisome biogenesis disorders, including rhizomelic chondrodysplasia punctata (RCDP), revealed that ZPG208 belonged to none of human CGs. ZPG207 was classified into the same CG as RCDP. Taken together, ZPG208 is in a newly identified, the 12th, CG in peroxisome-deficient CHO mutants reported to date and represents a novel mammalian CG.