Progress and Advances in Porous Silica-based Scaffolds for Enhanced Solid-state Hydrogen Storage: A Systematic Literature Review

Hydrogen plays a crucial role in the future energy landscape owing to its high energy density. However, finding an ideal storage material is the key challenge to the success of the hydrogen economy. Various solid-state hydrogen storage materials, such as metal hydrides, have been developed to realize safe, effective, and compact hydrogen storage. However, low kinetics and thermodynamic stability lead to a high working temperature and a low hydrogen sorption rate of the metal hydrides. Using scaffolds made from porous materials like silica to confine the metal hydrides is necessary for better and improved hydrogen storage. Therefore, this article reviews porous silica-based scaffolds as an ideal material for improved hydrogen storage. The outcome showed that confining the metal hydrides using scaffolds based on porous silica significantly increases their storage capacities. It was also found that the structural modifications of the silica-based scaffold into a hollow structure further improved the storage capacity and increased the affinity and confinement ability of the metal hydrides, which prevents the agglomeration of metal particles during the adsorption/desorption process. Hence, the structural modifications of the silica material into a fibrous and hollow material are recommended to be crucial for further enhancing the metal hydride storage capacity.

SPINK2 Protein Expression Is an Independent Adverse Prognostic Marker in AML and Is Potentially Implicated in the Regulation of Ferroptosis and Immune Response

There is an urgent need for the identification as well as clinicopathological and functional characterization of potent prognostic biomarkers and therapeutic targets in acute myeloid leukemia (AML). Using immunohistochemistry and next-generation sequencing, we investigated the protein expression as well as clinicopathological and prognostic associations of serine protease inhibitor Kazal type 2 (SPINK2) in AML and examined its potential biological functions. High SPINK2 protein expression was an independent adverse biomarker for survival and an indicator of elevated therapy resistance and relapse risk. SPINK2 expression was associated with AML with an NPM1 mutation and an intermediate risk by cytogenetics and European LeukemiaNet (ELN) 2022 criteria. Furthermore, SPINK2 expression could refine the ELN2022prognostic stratification. Functionally, an RNA sequencing analysis uncovered a potential link of SPINK2 with ferroptosis and immune response. SPINK2 regulated the expression of certain P53 targets and ferroptosis-related genes, including SLC7A11 and STEAP3, and affected cystine uptake, intracellular iron levels and sensitivity to erastin, a specific ferroptosis inducer. Furthermore, SPINK2 inhibition consistently increased the expression of ALCAM, an immune response enhancer and promoter of T-cell activity. Additionally, we identified a potential small-molecule inhibitor of SPINK2, which requires further characterization. In summary, high SPINK2 protein expression was a potent adverse prognostic marker in AML and might represent a druggable target.

Deep genomic characterization highlights complexities and prognostic markers of pediatric acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) is an uncommon but aggressive hematological malignancy. The poor outcome is attributed to inadequate prognostic classification and limited treatment options. A thorough understanding on the genetic basis of pediatric AML is important for the development of effective approaches to improve outcomes. Here, by comprehensively profiling fusion genes as well as mutations and copy number changes of 141 myeloid-related genes in 147 pediatric AML patients with subsequent variant functional characterization, we unveil complex mutational patterns of biological relevance and disease mechanisms including MYC deregulation. Also, our findings highlight TP53 alterations as strong adverse prognostic markers in pediatric AML and suggest the core spindle checkpoint kinase BUB1B as a selective dependency in this aggressive subgroup. Collectively, our present study provides detailed genomic characterization revealing not only complexities and mechanistic insights into pediatric AML but also significant risk stratification and therapeutic strategies to tackle the disease.

Mutational spectrum and prognosis in Chinese patients with prefibrotic primary myelofibrosis

Prefibrotic primary myelofibrosis (Pre‐PMF) has been classified as a separate entity of myeloproliferative neoplasms (MPNs). Pre‐PMF is clinically heterogeneous but a specific prognostic model is lacking. Gene mutations have emerged as useful tools for stratification of myelofibrosis patients. However, there have been limited studies comprehensively investigating the mutational spectrum and its clinicopathological significance in pre‐PMF subjects. In this study, we addressed these issues by profiling the mutation status of 141 genes in 172 Chinese MPN patients including 72 pre‐PMF cases. Our findings corroborated the clinical/molecular distinctiveness of pre‐PMF and suggested a refined risk classification strategy for this entity.

Association of HLA-B22 serotype with SARS-CoV-2 susceptibility in Hong Kong Chinese patients

The coronavirus disease 2019 (COVID‐19) is a highly infectious disease caused by SARS‐CoV‐2. Since its first report in December 2019, COVID‐19 has evolved into a global pandemic causing massive healthcare and socioeconomic challenges. HLA system is critical in mediating anti‐viral immunity and recent studies have suggested preferential involvement of HLA‐B in COVID‐19 susceptibility. Here, by investigating the HLA‐B genotypes in 190 unrelated Chinese patients with confirmed COVID‐19, we identified a significant positive association between the B22 serotype and SARS‐CoV‐2 infection (p = 0.002, Bonferroni‐corrected p = 0.032). Notably, the B22 serotype has been consistently linked to susceptibility to other viral infections. These data not only shed new insights into SARS‐CoV‐2 pathogenesis and vaccine development but also guide better infection prevention/control.

Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells

The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding sites for transcriptional regulators to modulate gene expression. Alterations of CREs have been implicated in various diseases including cancer. While promoters and enhancers have been the primary CREs for studying gene regulation, very little is known about the role of silencer, which is another type of CRE that mediates gene repression. Originally identified as an adaptive immunity system in prokaryotes, CRISPR/Cas9 has been exploited to be a powerful tool for eukaryotic genome editing. Here, we present the use of this technique to delete an intronic silencer in the human RUNX1 gene and investigate the impacts on gene expression in OCI-AML3 leukemic cells. Our approach relies on electroporation-mediated delivery of two preassembled Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes to create two double-strand breaks (DSBs) that flank the silencer. Deletions can be readily screened by fragment analysis. Expression analyses of different mRNAs transcribed from alternative promoters help evaluate promoter-dependent effects. This strategy can be used to study other CREs and is particularly suitable for hematopoietic cells, which are often difficult to transfect with plasmid-based methods. The use of a plasmid- and virus-free strategy allows simple and fast assessments of gene regulatory functions.

RUNX1 upregulation via disruption of long-range transcriptional control by a novel t(5;21)(q13;q22) translocation in acute myeloid leukemia

RUNX1 encodes a Runt-related transcription factor that is critical for hematopoiesis. In this study, through a combinatorial molecular approach, we characterized a novel t(5;21)(q13;q22) translocation involving RUNX1 that was acquired during the progression of myelodysplastic syndrome to acute myeloid leukemia (AML) in a pediatric patient. We found that this translocation did not generate RUNX1 fusion but aberrantly upregulated RUNX1. This upregulation was attributed to the disruption of long-range chromatin interactions between the RUNX1 P2 promoter and a silencer in the first intron of the gene. Characterization of the silencer revealed a role of SNAG repressors and their corepressor LSD1/KDM1A in mediating the effect. Our findings suggest that chromosomal rearrangements may activate RUNX1 by perturbing its transcriptional control to contribute to AML pathogenesis, in keeping with an emerging oncogenic role of RUNX1 in leukemia.

High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain

Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.

Metallic Nanoislands on Graphene for Monitoring Swallowing Activity in Head and Neck Cancer Patients

There is a need to monitor patients with cancer of the head and neck postradiation therapy, as diminished swallowing activity can result in disuse atrophy and fibrosis of the swallowing muscles. This paper describes a flexible strain sensor comprising palladium nanoislands on single-layer graphene. These piezoresistive sensors were tested on 14 disease-free head and neck cancer patients with various levels of swallowing function: from nondysphagic to severely dysphagic. The patch-like devices detected differences in (1) the consistencies of food boluses when swallowed and (2) dysphagic and nondysphagic swallows. When surface electromyography (sEMG) is obtained simultaneously with strain data, it is also possible to differentiate swallowing vs nonswallowing events. The plots of resistance vs time are correlated to specific events recorded by video X-ray fluoroscopy. Finally, we developed a machine-learning algorithm to automate the identification of bolus type being swallowed by a healthy subject (86.4%. accuracy). The algorithm was also able to discriminate between swallows of the same bolus from either the healthy subject or a dysphagic patient (94.7% accuracy). Taken together, these results may lead to noninvasive and home-based systems for monitoring of swallowing function and improved quality of life.

Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi2Se3/yttrium iron garnet heterostructures

Harnessing the spin–momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi₂Se₃/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi₂Se₃ film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi₂Se₃/YIG reveals signatures of the magnetic proximity effect of T_C as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices.

Understanding the effects of topological insulators on magnetization dynamics of adjacent magnetic materials is essential for novel spintronic devices. Here, Fanchiang et al. report thickness dependence of interfacial in-plane magnetic anisotropy and damping enhancement in Bi₂Se₃/yttrium iron garnet (YIG) bilayers, indicating an important role of topological surface states in the magnetization dynamics of YIG.

Abstract 2232: Down-regulation of dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A mediated by miR-1246 and miR-1290 in multiple myeloma cancer stem-like cells

Multiple Myeloma (MM) is a clonal plasma cell derived malignancy characterized with high relapse rate and fatality despite recent therapeutic advances. The existence of the rare population of CD138neg cancer stem-like cells had been identified and demonstrated to bear higher clonogenicity and self-renewal capacity when compared to the CD138pos major population. Besides, CD138neg MM cells are more resistant to common therapeutic agents treating MM including dexamethasone, lenalidomide and bortezomib. Therefore, targeting MM cancer-stem like cells could be critical to achieve a cure in MM. Previously, our lab had identified 2 microRNAs, miR-1246 and miR-1290 that are overexpressed in CD138neg MM cells in both cell lines and patient samples. Their target genes are being studied in the present study. CD138pos and CD138neg MM cells were isolated using MACS-immunomagnetic system and the purity of both CD138neg and CD138pos fraction were accessed by flow cytometry using PE anti-human CD138 antibody. The purity of each fraction was over 95% in 4 cell lines (U266, RPMI8226, OPM2 and KMS-12-PE) used. mRNA level of 7 putative targets (DYRK1A, KDM5A, NKRF, STK17A, PHLDA1, FOXA1, SCAI) chosen from TargetScan 6.2, miRanda or previous studies, which are related to tumor development in other cancers, of miR-1246 or miR-1290 were examined using RT-qPCR. Among the 7 putative targets, DYRK1A, KDM5A and NKRF were down-regulated in all four cell lines used. 3′UTR of the 3 down-regulated targets were cloned into pmirGLO Dual-Luciferase miRNA Target Expression Vector, which were co-transfected with miRNA-mimic into 293FT cells. Down-regulation of luciferase signal was observed in DYRK1A (p<0.05) and KDM5A (p<0.05). Mutagenesis of miR-1246 and miR-1290 binding sites of DYRK1A (but not in KDM5A) led to restoration of luciferase signal. Besides, mRNA and protein level of DYRK1A were also down-regulated 48 hours post-transfection of miRNA-mimics. The mRNA level of DYRK1A were also found to be significantly down-regulated in CD138neg cells when compared to CD138pos cells in 30 pairs of MM patient samples. Therefore, we conclude that DYRK1A should be a target of miR-1246 and miR-1290 in MM cells. Next, DYRK1A was knocked down by shRNA in U266. Preliminary results showed that down-regulation of DYRK1A reduced the percentage of apoptotic cells induced by treatment with bortezomib for 24 hours (p<0.05). Taken together, we had identified DYRK1A, which is down-regulated in MM cancer stem-like cells and regulated by miR-1246 and miR-1290. It may play a role in drug resistance in MM cancer stem-like cells. Our findings may provide insight on how MM cancer stem-like cells would escape from chemotherapy and facilitate the development of a novel therapeutic target in effective MM therapy.

Citation Format: Terry Hei Yan Wong, Coty HY Cheung, Natalie Pui Ha Chan, Rosalina KL Ip, Chi-Keung Cheng, Kitty Ka Yan Ng, Margaret H.L. Ng. Down-regulation of dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A mediated by miR-1246 and miR-1290 in multiple myeloma cancer stem-like cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2232. doi:10.1158/1538-7445.AM2015-2232

Abstract 5330: Differential expression and roles of miR-1246 and miR-1290 in multiple myeloma cancer stem cell-like subpopulation

Multiple myeloma (MM) remains an incurable clonal plasma cell malignancy. The existence of cancer stem cell-like subpopulation in MM may explain for its unfavourable prognosis and high relapse rate. Studies have shown that CD138neg MM cells were clonogenic and could be serially transplanted, while CD138+ cells could not. We characterized CD138neg cells by checking the presence of such subpopulation and their tumorigenic properties. In concordance with literature, CD138neg cells were present in MM cell lines, and possessed higher clonogenic potential than its non-tumorigenic counterpart as shown in colony formation assay. They were more quiescent, with less than 1% in G2/M phase compared to 5-10% in CD138+ cells. They also demonstrated higher resistance to chemotherapeutic agents, including thalidomide and bortezomib. Since studies in solid tumors have demonstrated that microRNA (miRNA) plays a role in self-renewal, tumorigenicity and chemoresistance in cancer stem cells, we hypothesized that specific miRNAs are the key regulators of the cancer stem cell-like functions in MM clonogenic cells. To search for these candidates, we first identified miRNAs that are differentially expressed among the two subpopulations, CD138+ and CD138neg cells, which were isolated from MM cell lines (NCI-H929, U266 and MM17, our in-house MM cell line) using MACS-immunomagnetic separation system and subjected to Exiqon miRCURY LNA miRNA microarray analysis. Ten candidate miRNAs were identified and selected for further validation by Taqman miRNA assay. By further independent investigation using fifteen MM patient samples, concordantly we found frequent up-regulation of miR-483-5p, miR-1246, miR-1275, miR-1290 and miR-3196 in CD138neg compared to CD138+ cells. MiR-1246 (93.4%, p = 0.006) and miR-1290 (93.4%, p = 0.0015) were chosen for further examination of the potential roles in MM pathogenesis and prognosis because they showed significantly higher expression levels in CD138neg cells than the CD138+ counterparts. Preliminary results showed that inhibiting miR-1246 (p = 0.0478) and miR-1290 (p = 0.0386) reduced cell proliferation in CD138neg cells at 24h or 48h of transfection in unsorted U266 cells, while CD138+ cells were not affected. As predicted using computational algorithms (miRANDA and TargetScan), the downstream targets of the two miRNAs include SEMA6A, STK17A, PHLDA1 and KLF9, which bear functions related to MM pathogenesis or known to be tumor suppressors. Moreover, we also confirmed that their mRNA expressions were down-regulated in U266 CD138neg cells compared with CD138+ cells.Taken together, we suggest that miR-1246 and miR-1290 may play a regulatory role in MM clonogenic cell proliferation. Our findings may provide a novel insight for the microRNA-based therapeutics that specifically targets the clonogenic progenitors, which may prove to be more effective for cure of MM.

Citation Format: Coty HY Cheung, Suk-Hang Cheng, Libby Li, Natalie Pui Ha Chan, Rosalina KL Ip, Chi-Keung Cheng, Margaret H.L. Ng. Differential expression and roles of miR-1246 and miR-1290 in multiple myeloma cancer stem cell-like subpopulation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5330. doi:10.1158/1538-7445.AM2013-5330

Clinically significant red blood cell antibodies in chronically transfused patients: a survey of Chinese thalassemia major patients and literature review

BACKGROUND

Red blood cell (RBC) alloimmunization is reported to occur at an incidence of 5.2% to 23.5% among patients with thalassemia requiring chronic transfusion. With very limited data on alloimmunization among the Chinese population, a territory-wide study has been performed to look at its prevalence among Chinese thalassemia major patients.

STUDY DESIGN AND METHODS

A retrospective study was conducted by reviewing RBC request records for patients with thalassemia major in Hong Kong from 2006 to 2009. Demographic information and serologic data were retrieved for analysis.

RESULTS

A total of 382 patients were identified and consisted of 190 males and 192 females with a median age of 23 ± 10.4 (range, 0.25 to 52) years. Eighty-eight patients (23.0%) were reported to have RBC antibodies. Of them, 114 alloantibodies, 18 autoantibodies, and 19 unidentified antibodies were identified. Anti-E (42, 39.3%), anti-Mi(a)/Mur (33, 30.85%), anti-c (14, 13.1%), and anti-Jk(a) (seven, 6.55%) were the commonest antibodies reported. However, one case of anti-K (0.9%) and two cases of anti-Fy(b) (1.9%) were reported. Seven of the 18 patients with autoantibodies contained a total of 13 alloantibodies. They were anti-E (five, 38.4%), anti-Mi(a)/Mur (four, 30.8%), anti-Jk(a) (two, 15.4%), anti-c (one, 7.7%), and anti-Fy(b) (one, 7.7%).

CONCLUSION

It is the first comprehensive study on Chinese thalassemia major patients. Clinically significant alloantibodies are different from those observed in the Western population, although antibodies developed against Rh antigens are still common. Chinese patients are less likely to have antibodies against Kell and Duffy blood group antigens, but are more prone to develop antibodies against the Miltenberger antigens.

Validation of a prediction rule for development of rheumatoid arthritis in patients with early undifferentiated arthritis

Objective:

To validate a model which predicts progression from undifferentiated arthritis (UA) to RA, in a Canadian UA cohort.

Methods:

The prediction rule, comprising variables which are scored from 0 to 13, with higher scores reflecting an increased risk of RA, was applied to baseline characteristics of all patients with UA. Progression to RA was determined at 6 months.

Results:

105 patients were identified. By 6 months, 80 (76%) had developed RA while 25 (24%) had developed another diagnosis. Number of tender and swollen joints, rheumatoid factor positivity, anti-cyclic citrullinated peptide positivity, poor functional status and high disease activity were associated with development of RA (p<0.01). Median prediction score was 8.0 for progressors, 5.0 for non-progressors. With these cut-off points, 18 (72%) patients with scores ⩽5 did not develop RA, while 35 (97%) with scores ⩾8 did develop RA.

Conclusions:

High scores in our cohort predicted those who progressed to RA by 6 months. Baseline scores ⩾8 corresponded with higher rates of progression.

Complex temporal patterns of spontaneous initiation and termination of reentry in a loop of cardiac tissue

A two-component model is developed consisting of a discrete loop of cardiac cells that circulates action potentials as well as a pacing mechanism. Physiological properties of cells such as restitutions of refractoriness and of conduction velocity are given via experimentally measured functions. The dynamics of circulating pulses and the pacer's action are regulated by two threshold relations. Patterns of spontaneous initiations and terminations of reentry (SITR) generated by this system are studied through numerical simulations and analytical observations. These patterns can be regular or irregular; causes of irregularities are identified as the threshold bistability (T-bistability) of reentrant circulation and in some cases, also phase-resetting interactions with the pacer.

Pulse electroplating of copper film: a study of process and microstructure

Copper films with high density of twin boundaries are known for high mechanical strength with little tradeoff in electrical conductivity. To achieve such a high density, twin lamellae and spacing will be on the nanoscale. In the current study, 10 microm copper films were prepared by pulse electrodeposition with different applied pulse peak current densities and pulse on-times. It was found that the deposits microstructure was dependent on the parameters of pulse plating. Higher energy pulses caused stronger self-annealing effect on grain recrystallization and growth, thus leading to enhanced fiber textures, while lower energy pulses gave rise to more random microstructure in the deposits and rougher surface topography. However in the extremes of pulse currents we applied, the twin densities were not as high as those resulted from the medium or relatively high pulse currents. The highest amount of nanoscale twinning was found to form from a proper degree of self-annealing induced grain structure evolution. The driving force behind the self-annealing is discussed.

Thermoregulatory sudomotor dysfunction and diabetic neuropathy develop in parallel in at-risk feet

AIMS

To establish the longitudinal relationship of foot complications to neuropathy based on a 4-year follow-up of diabetic patients stratified by sudomotor dysfunctions.

METHODS

One hundred and nineteen Type 2 diabetic patients and 36 non-diabetic subjects were initially registered in the prospective cohort study. Plantar skin temperature and sympathetic skin response (SSR) were used to monitor sympathetic mediated thermoregulation and sudomotor function. Peripheral somatic and central autonomic functions were studied using clinical, nerve conduction and cardiovascular reflex tests. At enrolment, the diabetic patients were classified into one of three groups by the progressive stages of sudomotor dysfunction: SSR+ (SSR present; 49 patients), SSR- (SSR absent; 41 patients) and at-risk group (SSR absent but with cracked skin involving partial thickness of the dermis; 29 patients).

RESULTS

The at-risk group had 13.4 times (95% confidence interval 1.4-125.7) higher plantar ulceration rates than the other two patient groups during the 4 years. Skin temperature elevation occurred in parallel with development of foot sweating problems. There were no significant differences between the three patient groups in the ratios of abnormal heart rate variation, orthostatic test and clinical neuropathy score at follow-up. After 4 years of follow-up, nerve conduction abnormalities were more frequent in the at-risk and SSR- groups than in the SSR+ group.

CONCLUSIONS

Early deterioration of small sympathetic fibres could not be quantified accurately by the clinical, somatic and autonomic tests. Assessing skin integrity and sudomotor function in at-risk individuals identifies early peripheral sympathetic neuropathy, even if the patients have no overt clinical symptoms.

Differential role of PR-A and -B isoforms in transcription regulation of human GnRH receptor gene

The presence of progesterone response element (PRE) in the 5'-flanking region of the human GnRH receptor (GnRHR) suggests the possible regulation of this gene by progesterone (P). In the present study, we examined the effects of P in transcriptional regulation of human GnRHR gene expression at the pituitary and placenta levels since the GnRHR has been detected in both tissues. By the use of transient transfection assays, a differential regulation of human GnRHR promoter activity by P was observed. P treatment resulted in a decrease in promoter activity in the pituitary alphaT3-1 cells, suggesting a P-mediated inhibitory action. Interestingly, P is found to have a stimulatory role at the placental expression of this gene. Addition of RU486 to, or inhibition of endogenous P production by, the placental JEG-3 cells leads to a decrease in promoter activity, which is reversed by the replacement of P. Further studies have identified a putative PRE, namely human GR-PRE (located between -535 and -521, related to translation start site), that may be responsible for the P action since the mutation of these motifs reversed the P-mediated effects. The binding of PR to this element is confirmed by antibody supershift assays. The physiological effects of P are mediated through two PR isoforms, namely PR-A and PR-B. In the present study, overexpression of human PR-A resulted in a decrease in human promoter activity in both pituitary and placental cells. Interestingly, overexpression of PR-B exhibits a cell-dependent transcriptional activity, whereby it functions as a transcription activator in the placenta but as a transcription repressor in the pituitary. In summary, our results demonstrated a differential usage of PR-A and PR-B in transcriptional regulation of human GnRHR gene expression by P at the pituitary and placenta levels.

Geometric parameters of the in vivo tissues at the lumbosacral joint of young Asian adults

STUDY DESIGN

Magnetic resonance images (MRIs) were used to determine the geometry of the tissues studied.

OBJECTIVE

To investigate the geometric parameters of tissues around the lumbosacral joint.

SUMMARY OF BACKGROUND DATA

Cross-sectional area (CSA), moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1), which are important in the study of spinal mechanics and models for the investigation of low back pain. It was insufficient information to describe the relative dimension of spinal tissues except muscles around the lumbar spine.

METHODS

MRIs from eight asymptomatic young Taiwanese male adults were collected to present CSA, moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1). Four pairs of trunk muscles, erector spinae, rectus abdominis, abdominal oblique externus, and psoas muscles, ligamentum flavum, and facet joints at the bilateral sides were studied.

RESULTS

Spinal tissues at the level of lumbosacral joint were determined. The CSAs of the spinal elements at the L5-S1 normalized by the CSA of trunk ranged from 5.42% (the erector spinae) to 0.14% (the ligamentum flavum). The moment arm of the spinal elements relative to the trunk width and depth ranged from 40.91% (rectus abdominis at the y direction) to 0.38% (ligamentum flavum at the x direction). The profile of geometric elements of lumbosacral joint in the Asian male subjects was similar to the data collected from the white population. The data also showed that right-left symmetry in the aforementioned dimension.

CONCLUSION

Normalized data of the CSA, moment arm, and line of action of the spinal tissues at the L5-S1 joint were reported in vivo through the MRI techniques. The profile of geometric elements of lumbosacral joint in the Asian male subjects did not differ from the white population. In addition to muscles, the geometry of facet joint and ligament was determined, which would be important to the calculation of force distribution on the lumbosacral joint.

Tracheal intubation using suspension laryngoscopy in an infant with Goldenhar's syndrome

We present a case of a ten-month-old boy with Goldenhar's syndrome and significant retrognathia in whom a tracheostomy was performed to relieve upper airway obstruction. Tracheal intubation was facilitated by direct suspension laryngoscopy using a slotted rigid laryngoscope. We propose this technique as an alternative method for tracheal intubation in infants and young children with a difficult airway. The management of the difficult airway in children with Goldenhar's syndrome is discussed.

Stress analysis of the disc adjacent to interbody fusion in lumbar spine

After anterior interbody fusion in the lumbar spine, the accelerated degeneration of the disc adjacent to the fusion levels was clinically observed. To understand the stress distribution of the adjacent disc, this study created a finite element model of the lumbar spine from L1-L5 vertebral body. The fusion model modified from the intact model was used to simulate the anterior interbody fusion. Various loading conditions, which included flexion, extension, lateral bending, and torsion, were applied to the finite element model to study the corresponding stress distribution. From the finite element model calculation, at a lower fusion site or more fusion levels, the stress of the disc adjacent to interbody fusion increased more than upper fusion site or single fusion level under flexion, torsion and lateral bending. Larger stress increase was estimated at the upper disc adjacent to interbody fusion than the lower disc adjacent to interbody fusion. In stress distribution, the upper disc adjacent to interbody fusion had a little alteration under torsion.

A case of pancreatic serous cystadenoma obstructing the distal pancreatic duct

We present a case of resected serous cystadenoma of the pancreas inducing marked dilatation of the main distal pancreatic duct. A 68-year-old woman, previously diagnosed with chronic pancreatitis, presented with upper abdominal pain. Abdominal US revealed a highly echoic mass in the pancreas. A CT scan disclosed a low density mass in the pancreas and dilatation of the main peripheral pancreatic duct. The mass demonstrated homogeneous and high signal intensity on T2-weighted magnetic resonance imaging (MRI). Selective abdominal arteriography showed the mass strained by the celiac artery. The tumor markers were CEA (2.4 ng/ml) and CA19-9 (6.1 U/ml). After the diagnosis of serous cystadenoma of the pancreas, the patient underwent distal pancreatectomy and splenectomy. The tumor (2.5 cm in diameter) consisted of grayish-white nodules and occupied the body of the pancreas. The tail of the pancreas was atrophic. Histopathological examination of the specimen showed a multilocular lesion containing numerous cysts with the inner surfaces evenly lined by one layer of cuboid or flat epithelial cells which stained positive for periodic acid-Schiff (PAS), evidencing serous cystadenoma. The patient is doing quite well one and a half years after the operation.

The influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics

OBJECTIVE

To investigate the influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics.

DESIGN

A finite element analysis was used to investigate the alteration of contact characteristics of the tibiofemoral joint due to inserting a pressure sensitive film between the contacting surfaces.

BACKGROUND

The discrepancy between actual contact behaviors of tibiofemoral joint of knee prosthesis and the measurement using Fuji pressure sensitive film was not discussed extensively. The change of direct contact circumstance of the tibiofemoral joint due to inserting a pressure sensitive film was not well reported.

METHOD

A two-dimensional finite element model of the tibiofemoral joint of knee prosthesis in the sagittal plane was constructed. Four different radii of the femoral component were used to investigate the conformity effect. Two-layers of plane strain element were used to model the pressure sensitive film. The influence of inserting a pressure sensitive film on the actual contact characteristics was analyzed by comparing the results of the change in contact radius.

RESULTS

Inserting a pressure sensitive film between contacting surfaces would disturb the original contact behaviors, especially in the lowest conformity design. The maximum difference of contact radius between the model simulating actual contact circumstance and the model with inserting a pressure sensitive film between contacting surface was 77% in the lowest conformity condition at the smallest load.

CONCLUSIONS

This study proposes a quantitative analysis of contact characteristics in the tibiofemoral joint of knee prosthesis between the models with and without inserting a pressure sensitive film into the contact surface. The measurement of contact area in artificial tibiofemoral joints by using Fuji pressure sensitive film is always overestimated its true contact area by 14-77%.

RELEVANCE

This study revealed the measurement of contact characteristics of artificial tibiofemoral joints by using Fuji pressure sensitive film which depends on not only the applied load, but also the conformity and material properties of the contact surface. Therefore, the information of the conformity and material properties of the contact surface should be provided as well as the applied load wherever a measurement of contact characteristics using Fuji pressure sensitive film is analyzed and interpreted.

PEG adsorption of autoantibodies and detection of alloantibodies in warm autoimmune hemolytic anemia

BACKGROUND

The purpose of this study was to evaluate the effectiveness of PEG in the adsorption of autoantibodies and the detection of alloantibodies in patients with warm autoimmune hemolytic anemia (WAIHA).

STUDY DESIGN AND METHODS

The study was divided into three parts. First, the effectiveness of antibody removal by a conventional adsorption procedure and that by the PEG adsorption method were compared by using commercial antisera adsorbed with antigen-positive RBCs. Second, patients' sera with known weak alloanti-E were used to test against screening cells after allogeneic adsorption to show nonspecific coating of antibodies and the dilution effect on the PEG adsorption procedure. Third, conventional and PEG one-cell sample allogeneic adsorptions of WAIHA patients' sera with and without alloantibodies were performed and compared.

RESULTS

In the first part, seven of the eight polyclonal antisera gave a lower titer and score when tested against antigen-positive RBCs in the indirect antiglobulin test; this indicated that PEG is more efficient in removing antibodies. In the second part, similar reaction patterns were observed in antibody screening tests on unadsorbed sera and on sera after the first, second, and third adsorptions, which indicated that there was no alloantibody loss, nonspecific antibody coating, or dilution effect when PEG was added in the allogeneic adsorption procedures. In the third part, a 40-percent increase in efficiency in reducing the number of adsorptions and an 85-percent decrease in completion time of the adsorption procedures were obtained when PEG was used for adsorbing sera from 16 patients with WAIHA. Both conventional and PEG procedures were capable of removing autoantibodies to identify the specificities of alloantibodies.

CONCLUSION

The PEG adsorption method is an effective, sensitive, and efficient method of enhancing auto- antibody adsorption and alloantibody detection. It can reduce the processing time and minimize the delay of urgent transfusions to patients with WAIHA and can indirectly enhance cost-effectiveness and decrease the labor-intensive testing required by these cases.

A cellular automata model of chromatography

Dynamic models of the behavior of solvent and solute molecules can be made using cellular automata. A chromatographic column was represented by use of a cellular automata grid of 43 x 200 spaces. Solvent (mobile phase), solute and stationary phase cells were designated to simulate the chromatographic situation. The movements of solute and solvent cells down the grid were monitored for different numbers of iterations, different flow rates and different affinities of the solutes for the stationary phase and the solvent for itself. The cellular automata dynamics were successfully able to model expected chromatographic behavior except in a few cases where the number of cells was not large enough to provide an average value reflective of the molecular situation.

Segment inertial properties of Chinese adults determined from magnetic resonance imaging

OBJECTIVE

To improve the simulation of the task of manual materials handling for Chinese laborers, this study estimated the inertial properties of Chinese adults by using magnetic resonance imaging.

DESIGN

Magnetic resonance imaging was used as a means of estimating inertial property. Following the estimation of inertial properties for the Chinese subjects, comparison between estimates for Chinese and Caucasian populations was made.

BACKGROUND

Estimates of segment inertial properties are frequently based on data and procedures developed from human cadaver studies in which inertial properties have been measured directly. The errors might be derived from the utilization of the Caucasian data were questioned in our previous study on the spinal force prediction of the Chinese subjects during manual lifting.

METHODS

Magnetic resonance images were scanned at a 20 mm interval from eight males aged 26 (S.D., 4) years. Tissues were differentiated and verified using adequate intensity thresholds on each slice, and the segmental volume and mass were integrated by slices. The moments of inertia for each segment were then determined about the anatomical axes using the parallel axis theorem.Results. Results showed that our estimates were close to the data derived by Dempster with a slight deviation. Larger percentages of mass were found in the upper arm (4.0%) and thigh (13.6%) than in previous studies. On the other hand, smaller moments of inertia about three axes were noted in the shank.

CONCLUSION

Biomechanical modeling of the human body requires accurate prediction of body segment parameters that include measures of volume, mass, center of mass, and moments of inertia. This study suggests the need to estimate the inertial properties of segments from the Chinese population. Application of the data may improve the simulation of the task of manual materials handling for Chinese laborers in the future studies.

RELEVANCE

Biomechanical modeling of the human body requires accurate prediction of body segment parameters that include measures of volume, mass, center of mass, and moments of inertia. To obtain the basic data of segment parameters for the Chinese adults, this study was proceeded with the magnetic resonance imaging technique.

Analysis of ultrahigh molecular weight polyethylene failure in artificial knee joints: thermal effect on long-term performance

The mechanism resulting in damage to and failure of ultrahigh molecular weight polyethylene (UHMWPE) tibial inserts was investigated on clinically retrieved components. The severity of the subsurface damage increased with the length of time that the component had been implanted. A theoretical analysis was developed to account for the generation of subsurface damage based on a heat transfer model. Friction generates surface heat during articulation of total knee systems. Due to the cooling effect of body fluid on the surface, the rise in temperature on the UHMWPE surface is lower than that below the surface. The peak temperature was estimated to occur on a plane positioned about 1 to 2 mm below the surface. This result was similar to the bulk temperature variation observed during in vivo and in vitro studies by other investigators. Although the difference in temperature on and below the surface is only a few degrees, the thermal effect becomes apparent after a long time and may be explained by the viscoelastic behavior of polymers: the temperature-time equivalence. It is therefore suggested that this thermal effect is another contributory factor to material damage, in addition to high stress and oxidative degradation (in appropriate cases). Therefore, any technological efforts aimed at improving the performance of artificial joint prostheses should minimize the thermal effects at the subsurface of the articular components.

A cellular automata model of an anticipatory system

An anticipatory system has been modeled using the dynamic characteristics of cellular automata. Rules governing the steps in an enzymatic conversion of substrates to products are operative in the system. A concentration of an intermediate product influences the creation of a supplemental enzyme that enhances the competence of an enzyme down stream. This anticipation of the future event creates a condition in which the concentration of a later substrate is suppressed, a property characteristic of the system. The model presents a useful opportunity to study a variety of aspects of this fascinating phenomena.

Cellular automata models of chemical systems

This paper describes the use of kinematic, asynchronous, stochastic cellular automata to model liquid properties, solution phenomena and kinetic phenomena encountered in complex biological systems. Cellular automata models of dynamic phenomena represent in silico experiments designed to assess the effects of competing factors on the physical and chemical properties of solutions and other complex systems. Specific applications include solution behavior, separation of immiscible liquids, micelle formation, diffusion, membrane passage, first- and second-order chemical kinetics, enzyme activity and acid dissociation. Cellular automata is thus considered as providing an exploratory method for the analysis of dynamic phenomena and the discovery and understanding of new, unexpected phenomena.

The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing

OBJECTIVE

To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing.

DESIGN

An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated.

BACKGROUND

The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well.

METHODS

Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component.

RESULTS

The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses.

CONCLUSIONS

This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses.

RELEVANCE

This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.

Failure of the all-polyethylene patellar component after total knee arthroplasty

From 1991 to 1996, 953 cases of porous-coated anatomic modular knee prostheses with all-polyethylene patellar components were implanted. Among them, 4 cases had breakage of the patellar component at the peg-button interfaces. One had loosening of the patellar component by cutting out the patellar bony bed. Heavy body weight, weakness of the pegs of the all-polyethylene patellar component, and osteonecrosis of the patella were conceived as the causes of failure.

An in vitro comparison of the motion behavior of different bipolar endoprostheses

The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical roundness of outer shells and inner heads of the bipolar prostheses were measured before the experiments. The acetabulum and outer shell of the bipolar prostheses were fixed on a Bionix 858 material testing system axially by separate fixation tools. The axial load of 1,400 N and 2,800 N was than applied on the specimen. The axis was rotated from 0 degrees to 90 degrees at the speed of 1 degree/s. All 3 outer shells were tested to this paired acetabulum randomly and separately. The frictional torque on the outer bearing surface of the different prostheses was recorded by the material testing system. The frictional torque on the inner bearing surface was also measured by the same procedure as was done for the outer bearing. The final results were statistically compared by the 1-way analysis of variance test method. Bipolar prostheses of the UHR system showed the largest frictional torque on outer bearing when it was loaded with 1,400 N and 2,800 N. The final results showed that all the bipolar prostheses had ideal motion behavior when functioning under the loading of 1,400 N. The frictional torque on the inner bearing was found to be larger than the frictional torque on the outer bearing in some prostheses when the loading was increased to 2,800 N. Thus, the bipolar endoprostheses functioned as unipolar prostheses. The only relative motion remained between the outer bearing surface and the acetabulum. This effect causes complications, such as implant protrusion in the acetabulum.

Isokinetic elbow joint torques estimation from surface EMG and joint kinematic data: using an artificial neural network model

Because the relations between electromyographic signal (EMG) and anisometric joint torque remain unpredictable, the aim of this study was to determine the relations between the EMG activity and the isokinetic elbow joint torque via an artificial neural network (ANN) model. This 3-layer feed-forward network was constructed using an error back-propagation algorithm with an adaptive learning rate. The experimental validation was achieved by rectified, low-pass filtered EMG signals from the representative muscles, joint angle and joint angular velocity and measured torque. Learning with a limited set of examples allowed accurate prediction of isokinetic joint torque from novel EMG activities, joint position, joint angular velocity. Sensitivity analysis of the hidden node numbers during the learning and testing phases demonstrated that the choice of numbers of hidden node was not critical except at extreme values of those parameters. Model predictions were well correlated with the experimental data (the mean root-mean-square-difference and correlation coefficient gamma in learning were 0.0290 and 0.998, respectively, and in three different speed testings were 0.1413 and 0.900, respectively). These results suggested that an ANN model can represent the relations between EMG and joint torque/moment in human isokinetic movements. The effect of different adjacent electrode sites was also evaluated and showed the location of electrodes was very important to produce errors in the ANN model.

Fracture of the femoral component associated with polyethylene wear and osteolysis after total knee arthroplasty

Fracture of the femoral component associated with polyethylene wear and osteolysis after total knee arthroplasty (TKA) has not been well reported before. A 63-year-old man with osteoarthritis of the right knee underwent TKA with a New Jersey LCS Knee, with cementing on the tibia and patella but not on the femoral component. After 42 months, in addition to wearing of polyethylene of the tibia and patella, severe osteonecrosis of the medial femoral condyle was noted. Osteonecrosis caused loss of osseous support of the medial flange of the femoral component, and the bone ingrowth of the central and lateral flange to the distal femur was so good that it overcame the yield stress of the metal of the femoral component and caused fracture of the femoral component. The osteolytic area was filled with autogenous iliac bone, and a new femoral component was inserted and cemented. The patient's condition became satisfactory with relief of pain. Although uncommon, fracture of the femoral component does occur associated with polyethylene wear and osteolysis.

Influences of walking speed change on the lumbosacral joint force distribution

To more understand the influence of the walking speed on the spinal joint force distribution, a three-dimensional biomechanical model was used to estimate the spine loads during human gait with three different walking speeds. This previously developed and validated model included a dynamic external model and an internal model with forces of disc, 8 major muscles, 2 ligaments and 2 facet joints at L5/S1 level. A linear optimization method was used to solve the internal model to estimate the L5/S1 spinal joint force distribution. The results of five young male subjects showed that the mean peak L5/S1 disc compressive forces on the slow, preferred and fast speeds were 2.28, 2.53, 2.95 body weight, respectively. The peak forces happened right after the heel strike and before completely toe off. The facet joint forces were generally increased with the walking speed increase, too. To reduce the loads on the spine, the slow walking is then recommended for the patients with low back pain or after spinal surgery.

A new approach of designing the tibial baseplate of total knee prostheses

OBJECTIVE

To improve the design of the knee prosthesis, a new technique to design the tibial baseplate of total knee prostheses was developed.

METHODS

One senior surgeon operated on 79 osteoarthrosis patients by using PCA total knee prostheses for total knee replacement. Four dimensions were measured intraoperatively and compared, including the anterioposterior length and the mediolateral width of the resected tibia plateau and implant. The data of anterioposterior length and the mediolateral width of resected surfaces of the tibial plateau of the 79 patients were plotted in a coordinate system. This coordinate system was formed with the mediolateral width as the x-axis and anterioposterior length as the y-axis. A circle, 5 mm in diameter, was used as the maximum coverage criterion. Five contemporary products and a new design product were used to screen the data to see how many patients would fall within the criteria. From the results of the screened data, we calculated the coverage percentage of the patients.

RESULTS

The ratio of the anterioposterior length to the mediolateral width of the resected surfaces of the tibial plateau was greater than that of the ratio of the PCA prostheses (P < 0.05). The results showed that no single product on the market had the patients meet over 70% of the criterion. A different ratio of the anterioposterior length to the mediolateral width was designed to achieve 90% coverage of the patients that met the criterion.

DISCUSSION

One possible explanation for the discrepancy between resected surfaces and implants is that the osteoarthrosis patients developed knee deformities that changed the surface of the tibial plateau and thus altered the knee dimensions. Since the total knee prostheses were used on osteoarthrosis patients, the dimensions of the resected tibial surfaces of osteoarthrosis patients should be considered in the design of the tibial baseplate of total knee prostheses.

Cementless Roy-Camille femoral component

From 1984 to 1987, a complete, single-layered, porous-coated femoral component (Roy-Camille type) was used for primary cementless total hip replacement in 80 patients. Seventy-two patients (77 hips) with a minimal follow-up of 5 years (mean 7.2 years) were assessed clinically and radiographically. Thigh pain occurred in 4 hips. Osteolysis appeared in 5 hips. Cortical thinning around the femoral component was significant at the proximal and middle levels. In total, 6 femoral components failed, which led to reoperation due to aseptic loosening (4 hips) and septic loosening (2 hips). The hip rating score (modified d'Aubigne and Postel rating system) in the surviving hips progressed from 9.0 (range 6-10) preoperatively to 16.3 (range 12-18) points at the latest follow-up. From this study, we found that the complete, single-layered, porous-coated stem had a low loosening rate after 5 years. Bone ingrowth into the porous coating was found in most of the cases. A lower stress shielding effect in comparison with the complete, multi-layered, porous-coated prosthesis was also noted.

Alzheimer's disease care: costs and potential savings

A cross-sectional study of 679 Alzheimer's disease patients from thirteen sites in nine states provides a unique opportunity to estimate costs of Alzheimer's disease care by disease stage and care setting and to explore potential areas of cost savings. In 1996 annual costs of caring for patients with mild, moderate, and severe Alzheimer's disease were $18,408, $30,096, and $36,132, respectively. Monthly savings of $2,029 in formal services are possible if disease progression can be slowed. Annual institutional cost savings of $9,132 also are achievable if alternative residential settings are used.

Comparison of muscle strength of posterior cruciate-retained versus cruciate-sacrificed total knee arthroplasty

One of the most controversial issues in total knee arthroplasty is whether to retain or sacrifice the posterior cruciate ligament (PCL). Investigators have used various methods to evaluate the influence of the PCL after total knee arthroplasty, but muscle strength evaluation has not been reported. The purpose of this study is to compare the long-term effects of PCL retention or sacrifice on muscle strength. Isokinetic testings and isometric testings were studied in patients with three different types of prosthesis design: total condylar, low contact stress rotating platform (both sacrifice PCL), and low contact stress meniscal bearing (retains PCL). The results showed that in all testing conditions, the hamstring to quadriceps ratios did not significantly differ among the three prosthetic designs (P > .05) even after long-term (6-13 years) functional adaptation.

Gain of muscle torque at low and high speed after isokinetic knee strengthening program in healthy young and older adults

Low-speed isokinetic exercise has been recommended to exert a maximal contraction and produce greater muscle torque than high-speed exercise in young adults. The purpose of this study was to compare the effectiveness of low- and high-speed isokinetic exercise programs for increasing muscle torque in young and elderly people. Twenty healthy elderly and 20 young subjects participated. The elderly subjects were divided into two groups. One group performed high-speed (300 degrees/s) isokinetic exercise training three times a week for the dominant-side knee extensor and low-speed (60 degrees/s) exercise for the non-dominant side for 6 weeks. The other group was trained using the reverse exercise regime. The training program for the young subjects was the same as that for the elderly groups. All subjects had their knee extensor torque evaluated with an isokinetic test before and at 2-week intervals during the training program. For young and elderly groups, both high- and low-speed isokinetic exercise training increased extensor torque in low- and high-speed tests. For the young group, low-speed exercise effectively improved muscle torque at low and high speeds. The improvement in slow muscle torque was significantly greater than that in fast muscle torque. For the elderly subjects, high-speed isokinetic exercise produced the greatest muscle torque at high speed in the first 2 weeks of training, and demonstrated a sharp increase in muscle torque in the final 2 weeks. Low-speed exercise frequently caused knee stress and the inability of some elder subjects to continue the exercises with maximal effort. Our findings indicate that high-speed exercise may be more appropriate for the elderly, and low-speed exercise may be more appropriate for younger people.

Polyethylene failure in New Jersey low-contact stress total knee arthroplasty

From January 1985 to December 1990, 598 consecutive New Jersey low-contact stress (LCS) total knee arthroplasties (TKAs) were performed for gonarthrosis. Among these 598 operations, 322 were with rotating platform elements and 276 were with meniscal bearing elements. During 5 to 8 years of follow-up, eight knees had severe symptomatic polyethylene failure that required revision surgery; all eight cases were meniscal bearing types. The failed polyethylene inserts were retrieved and studied. It was observed that there were four probable failure mechanisms associated with the catastrophic polyethylene wear. First, insufficient thickness of the meniscal bearing was the major reason for wear. Second, the malpositioning of the metal tibial tray in the transverse plane resulted in the breaking of the meniscal bearing. Third, the inability of the patellar to rotate due to tissue ingrowth made the polyethylene break. Last, yellowing of the subsurface of the meniscal bearing was a sign of polyethylene failure. These four possible failure mechanisms are all associated with the design of the meniscal bearing type of LCS knee prostheses. Therefore, it is suggested that the design of the LCS knee prosthesis should be modified.

The first case of the p phenotype in a Gurkha Nepalese

A serum sample from a Gurkha Nepalese soldier, residing in Hong Kong, was found to cause hemolysis of reagent ABO red cells (RBCs) in the reverse blood grouping test. Subsequent follow-up studies revealed that he was of the p phenotype, with potent anti-PP1Pk that was strongly hemolytic both at room temperature and 37 degrees C. The anti-PP1Pk was composed of IgG and IgM, and its various components were separable.

The effect of electrode arrangement on spectral distance measures for discrimination of EMG signals

The proper electrode placement in applying cepstral coefficients for electromyogram (EMG) signature discrimination was investigated. We measured EMG signals of different motions with two electrode arrangements simultaneously. Electrode pairs were located separately on dominant muscles (S-type arrangement) and closely in the region between muscles (C-type arrangement). The application of the cepstral method to signals derived from a C-type arrangement did not achieve the same discrimination as with a S-type arrangement. We used a simplified model to elucidate the poor performance in C-type signals. The bandwidth of signals obtained from S-type placement is wider than that from C-type. Narrower bandwidth decreases the importance of the more discriminative parts for both autoregressive (AR) and cepstral methods. The cepstral method is more sensitive to such variation, so the degradation in performance is more serious for the cepstral method. Second, the amplitude of C-type signal is lower than the S-type; therefore, the C-type signal is more sensitive to the disturbance of noise, especially in the high-frequency band. As high-frequency noise increases, the spectral difference between different EMG signals is gradually dominated by the low-frequency part, which is more informative. Thus, the performances of both methods are improved with increasing high-frequency noise. The improving rate of the AR method is faster than the cepstral method; therefore, its discriminative efficiency may exceed the cepstral method with C-type arrangement.

A cellular automata model of diffusion in aqueous systems

A cellular automata model of a solute diffusing in water has been created and studied for the influential attributes. The results with this model are in agreement with experimental results; that is, that lipophilic solutes diffuse faster than do polar solutes. The model reveals that a solution composed of a relatively lipophilic solute permits a greater extent of diffusion of another solute. This observation is in agreement with the model showing a diffusion preference of a solute between two solutions made up of differing polarities. The solute diffuses farther into the lipophilic solution. A temperature-lipophilicity phase diagram shows the influence of these two attributes on the rate of diffusion. A model of diffusion through solutions containing stationary ingredients reveals a faster rate when the ingredient is lipophilic. We are led to a conclusion that the relative lipophilicity of solutes or stationary ingredients in a solution has a direct influence on the rates of diffusion of other solutes in their midst.