Influence of microscopic surface asperities on the wear of ultra-high molecular weight polyethylene in a knee prosthesis.

The wear of ultra-high molecular weight polyethylene (UHMWPE) in knee and hip prostheses is one of the major factors restricting the longevity of these implants. A number of microscopic scratches caused by various factors were observed on the metallic femoral components of the retrieved knee prostheses with an anatomical design. It appears that microscopic surface asperities caused by this surface damage contribute to increasing and/or accelerating the wear of the UHMWPE tibial insert. In this study, in the first step, microscopic observations and surface roughness measurements of several retrieved metallic femoral components were performed in order to produce simplified two-dimensional (2D) finite-element method (FEM) models of a microscopic surface asperity using roughness parameters. Next, a three-dimensional (3D) microscopic surface profile measurement of the damaged surface of a retrieved metallic femoral component and the reproduction of the femoral component surface were performed in order to produce 3D FEM models of a microscopic surface asperity based on actual measurement data. 2D and 3D elastoplastic contact analyses between a metallic microscopic surface asperity and UHMWPE were also performed in order to investigate the mechanical state and microscopic wear of UHMWPE caused by a metallic microscopic surface asperity. The analytical findings of this study suggest that the aspect ratio, shape ratio, and indentation depth of the microscopic surface asperity have significant influence on increasing and/or accelerating the wear of UHMWPE. Higher aspect ratios, shape ratios, and indentation depths cause higher contact stresses and plastic strains in UHMWPE.

Elasto-plastic contact analysis of an ultra-high molecular weight polyethylene tibial component based on geometrical measurement from a retrieved knee prosthesis.

The wear phenomenon of ultra-high molecular weight polyethylene (UHMWPE) in knee and hip prostheses is one of the major restriction factors on the longevity of these implants. Especially in retrieved knee prostheses with anatomical design, the predominant types of wear on UHMWPE tibial components are delamination and pitting. These fatigue wear patterns of UHMWPE are believed to result from repeated plastic deformation owing to high contact stresses. In this study, the elasto-plastic contact analysis of the UHWMPE tibial insert, based on geometrical measurement for retrieved knee prosthesis, was performed using the finite element method (FEM) to investigate the plastic deformation behaviour in the UHMWPE tibial component. The results suggest that the maximum plastic strain below the surface is closely related to subsurface crack initiation and delamination of the retrieved UHMWPE tibial component. The worn surface whose macroscopic geometrical congruity had been improved due to wear after joint replacement showed lower contact stress at macroscopic level.

Destruxins, cyclodepsipeptides, block the formation of actin rings and prominent clear zones and ruffled borders in osteoclasts.

Bone-resorbing osteoclasts exhibit polarized morphological structures such as actin rings, clear zones, and ruffled borders. To gain insight into the mechanism of bone-resorbing activity of osteoclast and to discover new types of anti-resorptive agents, we have screened for natural compounds that inhibit the bone-resorbing activity of osteoclast-like multinucleated cells (OCLs). Destruxin B (DestB) and E (DestE), cyclodepsipeptides, were found to inhibit pit formation without affecting osteoclast differentiation and survival. Destruxins reversibly induced morphological changes in OCLs in a dose-dependent manner (DestB, 0.2-1 microM; DestE, 0.01-0.05 microM) and inhibited pit formation. Destruxin-induced morphological changes were accompanied by disruption of the actin rings in OCLs. The formation of actin rings in OCLs after adhesion was also inhibited by destruxins. Electron microscopical analysis revealed that destruxin-treated OCLs on dentine slices have no prominent clear zones and ruffled borders. The effective concentrations of destruxins on the morphological changes were almost the same as those that inhibited bone resorption in organ culture system. These results suggest that the anti-resorptive effects of destruxins result from induction of a disorder of the morphological structures in polarized OCLs.

Invasive pulmonary aspergillosis resulting in respiratory failure during neutrophil recovery from postchemotherapy neutropenia in three patients with acute leukaemia.

Respiratory failure is a severe complication of invasive pulmonary aspergillosis (IPA). Its pathogenesis is not well understood. We herein describe three cases of subacute respiratory failure that occurred during the recovery phase of neutropenia following induction chemotherapy for acute leukaemia with IPA. In each case, severe neutropenia (19-85 days), high-grade fever, severe anaemia, the use of granulocyte-colony-stimulating factor and increasing infusion volume were noted. As the neutrophil count was recovering, the shadows on the chest X-ray expanded with progressing hypoxia. We should pay attention to the respiratory failure during the recovery phase of neutropenia in patients with IPA.

Porcine enamel matrix derivative enhances trabecular bone regeneration during wound healing of injured rat femur.

To elucidate the effects of enamel matrix derivative (EMD: Emdogain) on bone regeneration in rat femurs after drill-hole injury, defects in bone were filled with either EMD or its carrier, PGA, as control. On postoperative days 4 to 28, dissected femurs were examined by means of various morphological approaches. In both experimental groups, formation of trabecular bone, which was immunostained for bone sialoproteins (BSP), had occurred in the medullary cavities at cylindrical bone defects on Day 7 postoperatively. Cuboidal osteoblasts were clearly observed on these newly-formed BSP-positive bone trabeculae. On Days 7 and 14, many multinucleated giant cells, which strongly expressed cathepsin K, had appeared on these bone trabeculae, indicating active bone remodeling. In these bone trabeculae, Ca and P weight % and Ca/P ratio were similar to those of cortical bone, and there was no significant difference between the PGA- and EMD-applied groups. Bone volume fraction of newly-formed bone trabeculae on Day 7 postoperatively was significantly higher in the EMD-applied group than in the PGA-applied controls. Because of active bone remodeling and the marked decrease of bone volume, on Days 14 and 28 postoperatively, however, there was no longer a significant difference in trabecular bone volume fraction between the experimental groups. Our results suggest that EMD possesses an osteo-promotive effect on bone and medullary regeneration during wound healing of injured long bones.

[A case of Chlamydia pneumonia and systemic lupus erythematosus (SLE) pleurisy].

A 40-year-old female was admitted with right chest pain. SLE was absent from her past history, although she complained of polyarthralgia in winter. Atypical pneumonia/pleuritis was suspected by chest X-ray film, showing a nodular shadow in the right lower field and moderate pleural effusion. Chlamydia pneumonia was diagnosed by elevated anti-C. psittsci antibody, while characteristics of pleural fluid revealed serositis accompanied by SLE because of the high titered anti-DNA antibody and the low titered complement. She was cured by clarithromycin and subsequent administration of prednisolone and cyclophosphamide.

Paralytic ileus due to strongyloidiasis: case report and review of the literature.

We report a rare case of a patient with ileus due to Strongyloides infection that occurred four times within a six-month period. The ileus was improved by treatment with ivermectin and there has not been a recurrence of the symptoms within the last two years.

[Clinical analysis on 127 cases of fungemia in Fukuoka University Hospital between 1984 and 1994].

A clinical analysis on 127 cases out of 140 cases presenting with fungemia at Fukuoka University Hospital between 1984 and 1994 was done. The number of the positive blood cultures during the same period was 1188 and the rate of fungemia was 11.8%. The rates generally increased in recent years, 9.0% (1984-1986), 10.2% (1987-1989) and 13.6% (1990-1994), but decreased after 1992. C. albicans has shown a tendency to decrease while C. parapsilosis and C. glabrata have increased in recent years thus suggesting the effect of the prevalence of intravenous hyperalimentation (IVH) and azole antifungal agents. Only 3.9% of the fungemia were preceded by bacteremia. In addition to the known risk factors for fungemia such as IVH (89.0%) and the antibacterial agents, H2-receptor antagonists were used in 58.3% of the cases. 14 cases of the fungemia were observed during the prophylactic use of antifungal drugs. Therefore, fungemia should always be kept in mind regarding the differential diagnosis for bacteremia when an indwelling venous catheter is used. The prompt extubation of the catheter in addition to the adjustment of the dosage of antifungal drugs in response to the status of the host defense system are thus considered to be important in the treatment of fungemia.

[Infective endocarditis--a review of 21 cases in last 10 years].

Twenty one cases of infective endocarditis in last 10 years were re-evaluated by Duke's criteria. Fourteen strains of Streptococcus viridans, 4 of Enterococcus faecalis, 1 of Haemophilus parainfluenzae were isolated from blood culture. As to the minimum inhibitory concentration (MIC) of 8 strains of Streptococci, imipenem revealed the lowest MIC value, following penicillin G, ceftriaxon not equal to ampicillin, vancomycin and gentamicin. One strain of them was penicillin-resistant (0.8 micrograms/ml). Serum inhibitory test (SIT) and serum bactericidal test (SBT) were undergone for 6 cases. The assay was efficient to determine penicillin-tolerance of causative bacterium. Vegetations were observed in 18 cases of 21 by the echo-cardiography, especially transesophageal echocardiography had better diagnostic sensitivity compared to transthoracic echocardiography. However, it took 12 weeks from the first febrile episode to achieve definite diagnosis. One of reasons to take such a long time to reach diagnosis was that major causative organism was S. sanguis, whose inflammatory reaction to the host was said to be strikingly weak.

[A case of tuberculous pyothorax after an interval of four years of finishing with the first treatment for pulmonary tuberculosis].

We reported a case of tuberculous pyothorax which developed at four years after finishing with the first treatment for pulmonary tuberculosis. A 50-year-old female was admitted to our hospital with right chest pain. Tuberculous pyothorax was diagnosed by means of polymerase chain reaction (PCR method) of pleural effusion and of histological findings of the pleural section. She was cured by operation, pleural drainage and anti-tuberculous drugs. The bone scincigram of 99mTc revealed accumulation in the right 9th rib, tuberculous empyema might have been a secondary development from osteomyelitis.

Adaptive multimode lubrication in natural synovial joints and artificial joints.

To examine the lubrication mechanisms in both natural synovial joints and artificial joints with artificial cartilages, pendulum tests of pig shoulder joints and simulator tests of sliding pairs of a stainless steel spherical component and natural articular cartilage or artificial cartilage have been conducted. Firstly, it was shown in pendulum tests of pig shoulder joints that both concentration of hyaluronic acid or viscosity and adsorbed film formation of proteins and phospholipids exerted a significant effect on frictional behaviour in swinging motion immediately after a loading of 100 N. Under a high load of 1 kN, low friction was observed under wide-ranging viscosity conditions, since a high load similar to body weight probably enhanced the squeeze film effect due to improved congruity. Next, frictional behaviour of sliding pairs in knee joint models, consisting of a stainless steel spherical surface and either specimens of pig tibial cartilage or polyvinylalcohol (PVA) hydrogel, was examined during walking in simulator tests. In these tests, the influences of lubricant viscosity and addition of protein on frictional behaviour were evaluated. For both compliant materials, the appropriate addition of gamma-globulin to sodium hyaluronate (HA) solution maintained low friction and protected rubbing surfaces under thin film conditions. These phenomena are discussed from the viewpoint of adaptive multimode lubrication.

Analysis of the expression of CagA and VacA and the vacuolating activity in 167 isolates from patients with either peptic ulcers or non-ulcer dyspepsia.

OBJECTIVES: The goals of this study were: 1) to examine the prevalence of cytotoxin-associated protein (CagA), vacuolating cytotoxin (VacA), and the vacuolating cytotoxin activity (VCA) in vitro of infecting Helicobacter pylori isolates and 2) to clarify the relation between the expression of these virulence factors and the occurrence of peptic ulceration. METHODS: One hundred sixty-seven clinical isolates of H. pylori from patients with peptic ulcer disease (gastric ulcer, 62 cases; duodenal ulcer, 48 cases) and nonulcer dyspepsia (57 cases) were studied regarding their genetic and phenotypic properties. RESULTS: Type 1 bacteria, which had both CagA and VCA, and type 2 bacteria, which did not express either CagA or VCA, represented 62.9% and 7.8%, respectively; the remaining 29.4% had an intermediate phenotype, expressing either CagA independent of the presence of VCA (CagA+VCA-) or vice versa (CagA-VCA+). CagA+VCA- and CagA-VCA+ bacteria represented 17.4 % and 12.0%, respectively, both of which were more numerous than the type 2 category. The proportion of the CagA-positive isolates was significantly higher in both the duodenal ulcer (97.9%) and gastric ulcer (83.9%) patients than in the non-ulcer dyspepsia patients (61.4%) (p < 0.01). On the other hand, the proportion of VacA/VCA-positive isolates was not significantly different between peptic ulcer disease and non-ulcer dyspepsia. CONCLUSIONS: The currently used classification of this bacterium based on the concomitant expression of CagA and VacA/VCA into the two major types is not adequate. The CagA-positive phenotype thus may be important as a virulence marker for peptic ulcer disease independent of the presence of VacA/VCA.

[Immunodeficiency and carcinogenesis in patients with chronic active Epstein-Barr virus infection].

Three adult patients with chronic active Epstein-Barr virus infection (CAEBV) had high anti-EBV-VCA antibody, positive anti-EA, low anti-EBNA and were associated with systemic lymphadenopathies and immunosuppression. The case 1 and 2 had elevated serum immunoglobulin levels, and recurrent infections, and case 3 showed pancytopenia. These 3 cases developed both EBV and latent membrane protein (LMP) positive malignant histiocytosis, EBV positive but LMP negative plasmacytoma, and EBV negative acute myelogeneous leukemia, respectively. It was suggested that CAEBV belonged to high risk groups for the development of malignant neoplasms. Since HLA of the case 1 and his father was identical, we conducted a in vitro cytotoxicity test using EBV transformed autologous B lymphocytes, K562 cells, and Raji cells to clarify the association of immunosuppression and HLA. The case 1 showed a low level of specific cytotoxicity to autologous EBV transformed B cells, while his parents were negative for the specific cytotoxicity. The patient and his parents developed inducible cytotoxicity to all targets after in vitro incubation of peripheral mononuclear cells with recombinant interleukin 2 (rIL-2) for 7 days. The patient and his mother showed lower enhancement of cytotoxicity, while HLA identical father could induce good cytotoxic activity to all targets as well as normal controls, indicating that a low IL-2 induced cytotoxic activity observed in CAEBV was independent of HLA associated immunoregulation at least in the case 1. Further studies are required to clarify the exact mechanisms responsible for the development of CAEBV.

[Comparison between monotherapy with imipenem/cilastatin sodium (IPM/CS) and combinations of IPM/CS and other drugs for treating bacterial infections in patients with hematopoietic disorders].

One hundred and nine patients with infections concurrent with hematopoietic disorders were treated with imipenem/cilastatin sodium (IPM/CS) either alone (IPM/CS monotherapy) or in combination with other antimicrobial drugs (IPM/CS combination therapy). The following results were obtained. 1. One hundred and nine patients were allocated at random to two groups: 53 patients to IPM/CS monotherapy and 56 patients to IPM/CS combination therapy. Fourteen patients (6 and 8 in the 2 groups, respectively) were excluded from the clinical evaluation. There were not significant differences between the two groups with respect to the background. 2. The efficacy rates of the 2 treatments against bacterial infections were as follows: in the IPM/CS monotherapy group, 62.5% in 8 patients with sepsis, 75.0% in 23 patients with fever of undetermined origin (FUO), 50.0% in 10 patients with pneumonia, and 68.3% in the 47 patients, and in the IPM/CS combination group, 85.7% in 7 patients with sepsis, 63.6% in 24 patients with FUO, 50.5% in 8 patients with pneumonia, and 67.4% in the 48 patients. The differences between the two groups were not significant. 3. Among the drugs used in combination with IPM/CS, antibiotics other than penicillins, cephalosporins, and aminoglycosides were used in 12 patients and a high efficacy rate of 91.7% was obtained. 4. Bacteriologically, 19 and 17 strains were isolated from the IPM/CS monotherapy and combination therapy groups respectively, and the eradication rates were 100% and 88.9% respectively. 5. Side effects were noted in 2 patients in the IPM/CS monotherapy group and 7 in the combination therapy group, but all of these resolved after discontinuation or completion of the treatment. The efficacies against severe bacterial infections in the presence of hematopoietic disorders were not different between IPM/CS alone and IPM/CS in combination with other antibiotics. Adverse reactions were uncommon with the monotherapy.

Chronic Prototheca meningitis.

A case of chronic meningitis caused by the achloric alga Prototheca wickerhamii is described, which has persisted for more than 6 years despite treatment with various antifungal agents. For the last year no treatment has been given, but the patient has no complaints.

[Clinical efficacy of sulbactam/cefoperazone for the treatment of geriatric patients with respiratory tract infections].

We performed clinical studies on sulbactam/cefoperazone (SBT/CPZ) for the treatment of geriatric patients with respiratory tract infections. Seven patients with pneumonia, 7 with acute bronchitis, 6 with chronic respiratory tract infections were treated with SBT/CPZ. The patients were administered with a daily dose of 2.0 g or 4.0 g for 4-14 days. The clinical responses were excellent in 3, good in 13, fair in 3, and poor in 1 patients. The efficacy rate was 80.0%. No side effects were observed in any patients, but elevations of GOT, GPT were observed in two cases. Causative organisms were E. coli (2 strains), P. aeruginosa (2), MSSA (1), MRSA (1), S. pneumoniae (1), H. influenzae (1), K. oxytoca (1), and E. aerogenes (1). The bacteriological effect rate was 60%. One strain of MRSA and one of two strains of P. aeruginosa persisted in 2 patients.

The purification of a GroEL-like stress protein from aerobically adapted Campylobacter jejuni.

From plate cultures of Campylobacter jejuni grown in room air a particulate protein of 62 kDa was isolated by ion-exchange chromatography. The protein had a square shape from the side view but when viewed from the top it had a star-shaped structure. The molecular size of the whole particle determined by gel filtration was 850 kDa which suggested the presence of 14 subunits of 62 kDa in each particle. The N-terminal 37 amino residues showed more than 80% homology with the sequence of these heat shock protein (HSP) 60 homologs of Chlamydia trachomatis, Helicobacter pylori, and Escherichia coli (GroEL). This protein is immunologically cross-reactive with the antiserum for the 60-kDa HSP of Yersinia enterocolitica. Production of the 62-kDa protein increased under heat stress and growth in an aerobic atmospheric environment. From these observations we concluded that the 62-kDa protein is a Campylobacter stress protein (Cj62) which belongs to the HSP 60 family.