Cementation of a polyethylene liner into a metal shell. Factors related to mechanical stability

BACKGROUND: Various clinical situations may make polyethylene liner exchange desirable in the setting of a well-fixed metal shell. Options have included a simple polyethylene liner exchange or revision of the entire acetabular shell. A recently introduced technique involves cementation of a new liner into a well-fixed metal shell. The purposes of this study were to quantify the mechanical integrity of this method of liner fixation, to evaluate the factors that may influence immediate liner fixation, and to compare this construct with a standard locking mechanism. METHODS: One modular acetabular cup design was evaluated. Variables that may contribute to the mechanical integrity of the construct were evaluated via lever-out and multiaxis dislocation testing methods. The variables included the size of the liner (undersized versus oversized), type of liner (all-polyethylene versus modular design), modification of the modular liner (unmodified versus grooved), and groove configuration (cruciform versus circumferential). Metal shells with and without screw-holes were also tested. The modular locking mechanism was used as the control. RESULTS: None of the constructs failed at the cement-metal interface. All undersized liners required significantly higher loads to failure than either the controls (p < 0.001) or the oversized liners (p < 0.001). Oversized unmodified liners failed at significantly lower loads than the controls did (p < 0.01). The creation of circumferential grooves in the oversized liners significantly improved the strength of the constructs (p < 0.01), making them comparable with the controls. No significant differences were found among the four undersized groups (p > 0.3). The standard locking construct (control) and the oversized unmodified construct failed at a force of 2000 N in the multiaxis dislocation test. No other construct failed with use of this test mode. CONCLUSIONS: Cementation of a polyethylene liner into a metal shell can be stronger than a conventional locking mechanism if the liner is undersized. Cementation of an oversized liner into a shell should be performed with caution. The long-term durability of this fixation remains unknown.     

Mechanism of action of dietary chemoprotective agents in rat liver: induction of phase I and II drug metabolizing enzymes and aflatoxin B1 metabolism

A range of potential chemoprotective agents, most of them natural dietary constituents, has been examined for ability to modulate both phase I (cytochrome P450 1A1, 1A2, 2B1/2, 2C11, 2E1, 3A, 4A) and phase II drug metabolizing enzymes (glutathione S-transferases, in particular subunits Yc2 and P, aflatoxin B1-aldehyde reductase and quinone reductase) in rat liver. In addition to assays of total enzyme activity and Western blots for individual isozymes, the ability of microsomes to metabolize aflatoxin B1, and of cytosols to conjugate aflatoxin B1 (AFB1)-epoxide to GSH and to produce AFB1-dialcohol, were measured. Induction of gamma-glutamyl transpeptidase activity was examined by histochemistry. Differing patterns of induction were observed, reflecting differences in the control of expression of the individual enzymes studied. Of the compounds examined, butylated hydroxytoluene, ethoxyquin, indole-3-carbinol and phenethyl isothiocyanate were the most potent bifunctional agents (inducing both phase I and II activities). Oltipraz, while only weakly inducing CYP1A2 and 2B1/2, was a potent inducer of phase II enzymes. Caffeic acid, garlic oil, sinigrin and propyl gallate all showed some ability to induce phase II enzymes. 4-Methyl catechol, alpha-tocopherol and red wine decreased certain phase I enzyme activities, while inducing total GST activity. Butylated hydroxytoluene, ethoxyquin, garlic oil and indole-3-carbinol induced gamma glutamyltranspeptidase in periportal hepatocytes. Particularly because of their ability to induce the detoxifying activities of glutathione S-transferase Yc2 and aldehyde reductase, butylated hydroxytoluene, ethoxyquin, indole-3-carbinol, oltipraz, phenethyl isothiocyanate and sinigrin will be effective blocking agents in rodents, if administered prior to AFB1. While these studies indicate the relative contributions of phase I and II metabolism in the overall protective effect in rat, care should be taken that a similar balance is achieved in man, and that relevant enzymes or iso forms are induced.      

Flow cytometric enumeration of micronucleated reticulocytes: high transferability among 14 laboratories

This laboratory previously described a single-laser flow cytometric method, which effectively resolves micronucleated erythrocyte populations in rodent peripheral blood samples. Even so, the rarity and variable size of micronuclei make it difficult to configure instrument settings consistently and define analysis regions rationally to enumerate the cell populations of interest. Murine erythrocytes from animals infected with the malaria parasite Plasmodium berghei contain a high prevalence of erythrocytes with a uniform DNA content. This biological model for micronucleated erythrocytes offers a means by which the micronucleus analysis regions can be rationally defined, and a means for controlling interexperimental variation. The experiments described herein were performed to extend these studies by testing whether malaria-infected erythrocytes could also be used to enhance the transferability of the method, as well as control intra- and interlaboratory variation. For these studies, blood samples from mice infected with malaria, or treated with vehicle or the clastogen methyl methanesulfonate, were fixed and shipped to collaborating laboratories for analysis. After configuring instrumentation parameters and guiding the position of analysis regions with the malaria-infected blood samples, micronucleated reticulocyte frequencies were measured (20,000 reticulocytes per sample). To evaluate both intra- and interlaboratory variation, five replicates were analyzed per day, and these analyses were repeated on up to five separate days. The data of 14 laboratories presented herein indicate that transferability of this flow cytometric technique is high when instrumentation is guided by the biological standard Plasmodium berghei.     

Insulin-like growth factor (IGF)-I and IGF binding protein-3 concentrations in fluid from human stimulated follicles

Insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP- 3) play an important role in regulating follicle growth and maturation. We have evaluated whether responsiveness to gonadotrophins during an in- vitro fertilization (IVF) treatment is related to follicular fluid IGF- I and IGFBP-3 concentrations. We also investigated if a difference is present in IGF-I and IGFBP-3 concentrations between patients treated with human menopausal gonadotrophin (HMG) and patients treated with highly purified follicle stimulating hormone (FSH). We have measured IGF-I and IGFBP-3 in follicular fluid from pre-ovulatory follicles in an IVF programme. All 70 patients were stimulated after being down- regulated with a gonadotrophin-releasing hormone (GnRH) analogue. IGF-I concentrations in follicular fluid were significantly inversely correlated with the number of ampoules FSH administered and number of days of FSH administration, and significantly correlated with the number of follicles aspirated. IGFBP-3 concentrations were not correlated with any other parameter measured nor were IGF-I and IGFBP-3 concentrations correlated. IGFBP-3 concentrations were significantly higher in patients receiving highly purified FSH compared with patients receiving HMG (P < 0.005). These results are new evidence that IGF-I concentration in follicular fluid is higher in women who respond better to follicular stimulation, i.e. women who grow many follicles, women who need a shorter duration of stimulation and women who need fewer ampoules FSH before oocyte retrieval.      

Immunosuppressive activities in the seminal plasma of infertile men: relationship to sperm antibodies and autoimmunity

Semen samples from infertile men were assessed for sperm autoimmunity by direct immunobead assay for immunoglobulin (Ig)A and IgG sperm antibodies and mucus penetration test. Immunosuppressive activity in seminal plasma was measured by an in-vitro bioassay employing dose- dependent inhibition of phytohaemagglutinin-induced activation of rat thymocytes, in the presence or absence of hydroxylamine (0.1 mM), an inhibitor of polyamine oxidation. All seminal plasma samples, regardless of autoimmune status, caused inhibition of T-lymphocyte activation, and hydroxylamine reduced this bioactivity by appproximately 50%. Dialysis (<3500 molecular weight) also significantly reduced seminal plasma bioactivity, both in the presence and absence of hydroxylamine. In the presence of hydroxylamine, there was a negative correlation between IgA, but not IgG, antibody concentrations and lymphosuppressive activity in seminal plasma. Antibody-positive samples displaying impaired sperm function, as indicated by the mucus penetration test, had reduced activity compared with other samples. In contrast, there was no relationship between sperm autoimmunity and lymphosuppressive activity assayed in the absence of hydroxylamine. The data indicate that T-lymphocyte inhibition by human seminal plasma is due to multiple factors, and reduced amounts of these factors may contribute to the development and/or persistence of sperm autoimmunity in infertile men; however, differences in polyamine substrates available for oxidation in semen do not appear to be a major contributing factor.      

DNA sequence analysis of spontaneous and N-ethyl-N-nitrosourea-induced hprt mutations arising in vivo in cynomolgus monkey T-lymphocytes.

The study of hprt mutations in cynomolgus monkey T-lymphocytes is part of our effort to understand the mechanisms of mutagenesis in vivo. This primate model allows us to study mutations and their kinetics at the molecular level under well-controlled conditions using recently developed techniques for selection of mutant T-cells and polymerase chain reaction (PCR) amplification of hprt cDNA, which is directly sequenced. This is the first report of the sequence of the coding region of the cynomolgus monkey hprt gene and PCR/DNA sequence analysis of seven spontaneous mutant T-cell clones, as well as 23 mutant clones isolated 63 and 601 days after treatment with ethylnitrosourea (ENU, 77 mg/kg, intraperitoneal). cDNA was reverse transcribed from hprt mRNA directly from a lysate of about 2-4 x 10(3) cells, and a 700 bp fragment including the coding region was amplified by PCR and sequenced. Of the seven spontaneous mutants, only one point mutation (GC----AT transition) was detected, and the other six failed to amplify by PCR, possibly due to functional deletions. Of the 14 mutant clones isolated 63 days after ENU treatment, nine base substitutions were detected in ten clones: four transitions (three AT----GC and one GC----AT) and five transversions (four AT----TA and one AT----CG). Of the nine mutants isolated 601 days after ENU treatment, six single base substitutions were detected in six clones (five AT----TA and one AT----CG transversions), and one mutant had a large deletion or insertion. No changes were detected in three clones (one Day 63 and two Day 601 clones). In summary, only one of 15 single base substitutions isolated after ENU treatment was a GC----AT transition mutation and the rest were transitions and transversions at AT sites.     

肝炎后高胆红素血症18例分析

0　引言　肝炎后高胆红素血症 ,极易与肝炎伴发高胆红素血症相混淆 .该病是肝炎后遗症之一 ,临床上并不少见 .患者常以间歇性黄疸或隐性黄疸前来就诊 ,但并无先天性黄疸、肝炎、肝硬化及肝内外胆管结石的临床证据 ,多数既往有肝炎病史 ,肝炎已达治愈标准 ,虽增加活动量亦无复发 ,临床预后良好 .现将我院 1995 - 10 / 1999- 0 9肝炎后高胆红素血症 18例作一小结 .1　临床资料　男 12例 ,女 6例 ,年龄 2 2～ 5 8(平均 40岁 ) .门诊 11例 ,住院 7例 .其中 11例曾患急性病毒性乙型肝炎 ,1例曾患中毒性肝炎 ,1例曾患药物性肝炎 ,5例无明确肝炎病…     

Change in obesity‐related metabolic abnormalities associated with body mass index improvement through life‐style intervention: A meta‐regression

The reduction in body mass index standard deviation score (BMI‐SDS) associated with improvement in biomarkers relating to metabolic health in obese children is unknown. We aimed to establish the change in BMI‐SDS associated with improved inflammation, liver function, and insulin resistance to inform clinical guidelines for pediatric weight management interventions and to assess the efficacy of future trials. A large‐scale systematic review was conducted to identify relevant studies. Studies of children with a diagnosis of obesity according to defined BMI thresholds, participating in lifestyle interventions to reduce obesity, were included. Studies must have reported baseline (pre‐) and postintervention (or change of) BMI‐SDS and either fasting glucose, homeostatic model of insulin resistance (HOMA‐IR), alanine aminotransferase (ALT), C‐reactive protein (CRP), or interleukin‐6 (IL‐6). A series of meta‐regressions were conducted to establish links between BMI‐SDS change scores and change in metabolic markers of health. Sixty‐eight articles were identified. From the meta‐regression analyses, across all study subsets, greater mean falls in all four parameters, (HOMA‐IR, Glucose, ALT, and CRP) were observed with greater mean loss of BMI‐SDS, but the trends were only statistically significant for HOMA‐IR and CRP (P = .003; P = .021). However, we could not find minimum changes in BMI‐SDS that would ensure a fall in these outcomes. At this time, we are unable to recommend a definitive value of BMI‐SDS reduction needed to improve the markers of metabolic health. Future trials should aim to report additional indices of derived BMI values, which may better reflect changes in actual adiposity.     

De novo microduplications at 1q41, 2q37.3, and 8q24.3 in patients with VATER/VACTERL association

The acronym VATER/VACTERL association describes the combination of at least three of the following congenital anomalies: vertebral defects (V), anorectal malformations (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb defects (L). We aimed to identify highly penetrant de novo copy number variations (CNVs) that contribute to VATER/VACTERL association. Array-based molecular karyotyping was performed in a cohort of 41 patients with VATER/VACTERL association and 6 patients with VATER/VACTERL-like phenotype including all of the patients'' parents. Three de novo CNVs were identified involving chromosomal regions 1q41, 2q37.3, and 8q24.3 comprising one (SPATA17), two (CAPN10, GPR35), and three (EPPK1, PLEC, PARP10) genes, respectively. Pre-existing data from the literature prompted us to choose GPR35 and EPPK1 for mouse expression studies. Based on these studies, we prioritized GPR35 for sequencing analysis in an extended cohort of 192 patients with VATER/VACTERL association and VATER/VACTERL-like phenotype. Although no disease-causing mutation was identified, our mouse expression studies suggest GPR35 to be involved in the development of the VATER/VACTERL phenotype. Follow-up of GPR35 and the other genes comprising the identified duplications is warranted.     

Catalog of intravascular contrast media

The ionic intravascular contrast media formulations now commercially available are presented, along with those new formulations, nonionic and ionic, that have a significant reduced osmolality compared with those previously available.