Aerobic power and muscle strength of individuals living with HIV/AIDS.

AIM: We wished to evaluate any continuing adverse effects upon peak aerobic power and muscle strength associated with either HAART therapy or persistently low CD4⁺ counts in men living with HIV/AIDS. METHODS: We studied 39 HIV/AIDS patients with an average disease history of 6.1 years, and 28 normal sedentary volunteers. All subjects performed tests of peak aerobic power and isokinetic muscle force, and the HIV/AIDS group also completed the Profile of Mood States (POMS) and WHO Quality of Life questionnaires. Blood was sampled for standard measures of immune function (CD4⁺ and CD8⁺ counts) and viral load. RESULTS: Patient values were generally as in the normal subjects and appeared to be uninfluenced by the CD4+ nadir or the use of HAART therapy. However, the isokinetic muscle strength was lower in individuals with a low current CD4⁺ count. Isokinetic strength was also negatively correlated with current CD4⁺ and CD8⁺ counts. CONCLUSION: HAART therapy does not appear to have an adverse long-term effect on either aerobic power or muscle strength. Many ambulatory volunteers living with HIV/AIDS have a normal peak aerobic power. However, isokinetic strength can remain low, particularly in those with low current T-cell counts.

Carboxylic ionophores enhance the cytotoxic potency of ligand- and antibody-delivered ricin A chain.

The highly selective cytotoxicity of site-directed ricin A chain conjugates can be potentiated by membrane-active carboxylic ionophores. The combined use of the two agents results in much faster inactivation of ribosomes and subsequent cell death and lysis. The potency of A chain cytotoxins is correspondingly increased by several orders of magnitude and cells that sparsely express the target antigen or receptor can be killed.

A NURBS-based technique for subject-specific construction of knee bone geometry.

Subject-specific finite element (FE) models of bones that form the knee joint require rapid and accurate geometry construction. The present study introduces a semi-automatic non-uniform rational B-spline (NURBS) technique to construct knee bone geometries from computed tomography (CT) images using a combination of edge extraction and CAD surface generation. In particular, this technique accurately constructs endosteal surfaces and can accommodate thin cortical bone by estimating the cortical thickness from well-defined surrounding bone. A procedure is also introduced to overcome the bifurcation at the femoral condyles during surface generation by combining transverse and sagittal plane CT data. Available voxel- and NURBS-based subject-specific construction techniques accurately capture periosteal surfaces but are limited in their ability to capture endosteal geometry. In this study, the proposed NURBS-based technique and a typical voxel mesh technique captured periosteal surfaces within an order of magnitude of image resolution. The endosteum of diaphyseal bone was also captured with similar accuracy by both techniques. However, the voxel mesh model failed to accurately capture the metaphyseal and epiphyseal endosteum due to the poor CT contrast of thin cortical bone, resulting in gross overestimation of cortical thickness. The proposed technique considered both the local and global nature of CT images to arrive at a description of cortical bone thickness accurate to within 2 pixel lengths.

Validating an imaging and analysis system for assessing torso deformities.

We present the results of the numeric and functional validation of an imaging and analysis system used for assessing human torsos for deformities such as scoliosis. The system comprises of image acquisition, image reconstruction, and shape analysis components. The numeric validation procedure consists of assessing the accuracy of reconstruction of the system using inanimate models (a calibration box and a mannequin). The functional validation involves determining the system's response to variations in shape caused by sway and breathing, and evaluating the variability of a clinically relevant index, the Cosmetic Score, from multiple scans of scoliosis and non-scoliosis volunteers. Results show that the reconstruction accuracy of the system is 1.16+/-1.04 mm. This is better than the required accuracy for monitoring scoliosis of 2 mm. The system is robust to shape variations caused by sway and breathing and shows limited variability to the Cosmetic Score.

A machine learning approach to assess changes in scoliosis.

This paper presents a machine learning approach that can be used to evaluate the validity of the results obtained with an automated system to measure changes in scoliotic curves. The automated system was used to measure the inclinations of 141 vertebral endplates in spine radiographs of patients with scoliosis. The resulting dataset was divided into training and test set. The training set was used to configure three classifiers: a support vector classifier (SVC), a decision tree classifier (DT) and a logistic regression classifier (LR). Their performance was evaluated on the test set. The SVC had an accuracy of 86% discriminating Good Results (those in which the error was less than 3 degrees ) from Bad Results. This accuracy was better than that of the LR (76%) and DT (68%). The differentiation between Good and Bad Results using the proposed machine learning approach was achieved successfully.

Contribution of loading conditions and material properties to stress shielding near the tibial component of total knee replacements.

This communication reports important preliminary results of a parametric analysis into the stress shielding effects of loading conditions and material properties of a total knee replacement (TKR) prosthesis. A previously developed finite element (FE) model of the proximal tibia that incorporated orthotropic and heterogeneous bone properties was used. Tibiofemoral joint compression and soft tissue (ligament and muscle) forces were also included to better represent the loading condition in the tibia. Stress shielding effects were studied for a prosthesis similar to a commercially available model. Results from the model show that the hypothesis of relatively higher Young's modulus of implant compared to bone as the primary cause of stress shielding is not sufficiently descriptive. Loading conditions as a result of altered bone or implant condylar surface geometry, load placement on the condylar surface, and load pattern created by the TKR are at least as important or, in some cases, more important factors in observed stress shielding immediately post-operation. This finding can be used to focus new implant design on altered loading conditions as well as material selection.

The effect of pulsed electromagnetic fields on chondrocyte morphology.

Osteoarthritis is a debilitating joint disease where the articular cartilage surface degrades and is unable to repair itself through natural processes. Chondrocytes reside within the cartilage matrix and maintain its structure. We conducted in vitro experiments to investigate the morphological response of cultured human chondrocytes under different pulsed electromagnetic field (PEMF) conditions. In the control experiments, cultured chondrocytes attached to the bottom of a culture dish typically displayed either a stellate or spindle morphology with extended processes. Experimental chondrocyte cultures were placed in a Helmholtz coil to which a ramp waveform was applied. Exposure to PEMFs caused the chondrocytes to retract their processes, becoming spherical in shape. This change in morphology followed a progression from stellate to spindle to spherical. These morphological changes were reflected in an average reduction of 30% in the surface contact area of the chondrocytes to the culture dish. Understanding the mechanisms by which PEMFs affect the morphology of chondrocytes will help lead to new treatments for osteoarthritis.

Impact of acute exposure to air pollution on the cardiorespiratory performance of military firemen.

The objective of the present study was to determine the impact of acute short-term exposure to air pollution on the cardiorespiratory performance of military firemen living and working in the city of Guarujá, São Paulo, Brazil. Twenty-five healthy non-smoking firemen aged 24 to 45 years had about 1 h of exposure to low and high levels of air pollution. The tests consisted of two phases: phase A, in Bertioga, a town with low levels of air pollution, and phase B, in Cubatão, a polluted town, with a 7-day interval between phases. The volunteers remained in the cities (Bertioga/Cubatão) only for the time required to perform the tests. Cumulative load 10 +/- 2 min-long exertion tests were performed on a treadmill, consisting of a 2-min stage at a load of 7 km/h, followed by increasing exertion of 1 km h-1 min-1 until the maximum individual limit. There were statistically significant differences (P < 0.05) in anaerobic threshold (AT) between Cubatão (35.04 +/- 4.91 mL kg-1 min-1) and Bertioga (36.98 +/- 5.62 mL kg-1 min-1; P = 0.01), in the heart rate at AT (AT HR; Cubatão 152.08 +/- 14.86 bpm, Bertioga 157.44 +/- 13.64 bpm; P = 0.001), and in percent maximal oxygen consumption at AT (AT%VO2max; Cubatão 64.56 +/- 6.55%, Bertioga 67.40 +/- 5.35%; P = 0.03). However, there were no differences in VO2max, maximal heart rate or velocity at AT (ATvel) observed in firemen between towns. The acute exposure to pollutants in Cubatão, SP, caused a significant reduction in the performance at submaximal levels of physical exertion.

A support vector machines classifier to assess the severity of idiopathic scoliosis from surface topography.

A support vector machines (SVM) classifier was used to assess the severity of idiopathic scoliosis (IS) based on surface topographic images of human backs. Scoliosis is a condition that involves abnormal lateral curvature and rotation of the spine that usually causes noticeable trunk deformities. Based on the hypothesis that combining surface topography and clinical data using a SVM would produce better assessment results, we conducted a study using a dataset of 111 IS patients. Twelve surface and clinical indicators were obtained for each patient. The result of testing on the dataset showed that the system achieved 69-85% accuracy in testing. It outperformed a linear discriminant function classifier and a decision tree classifier on the dataset.

Cure of experimental human malignant mesothelioma in athymic mice by diphtheria toxin.

A single ip or iv dose of 1-3 micrograms of diphtheria toxin consistently cured athymic mice of an advanced stage experimental human malignant mesothelioma. All cancer cells were killed within 18 hours and the profuse ip ascites plus large solid tumor masses associated with this model of neoplastic disease were subsequently eliminated. Treated mice appeared normal in 3 days and lived for greater than 300 days with no signs of recurrence, while control animals did not survive greater than 32 days. The complete tumoricidal effect implies that toxin readily reached, entered, and preferentially killed each human cancer cell. This outcome exemplifies the true therapeutic potential of highly selective, site-directed toxins, and offers a frame of reference for judging the performance of current as well as prospective toxin-based agents.

Potentiation of antitumor immunotoxins by liposomal monensin.

BACKGROUND: The cytotoxicity of specific ricin A-chain immunotoxins is greatly enhanced in vitro by the carboxylic ionophore monensin. However, the highly lipophilic nature of monensin, which is reflected in its poor solubility and short half-life, has restricted its use in in vivo animal studies. PURPOSE: The purpose of this study was to assess the ability of monensin incorporated in unilamellar vesicles (liposomes) to potentiate antitumor immunotoxins in vitro and in vivo. METHODS: Monensin was incorporated into liposomes and used in combination with specific immunotoxins against human tumor cell lines in vitro and in vivo. Inhibition of [3H]leucine incorporation was used to evaluate the cytotoxic action of immunotoxin with or without monensin in vitro on the following human tumor cell lines: H-MESO-1 malignant mesothelioma, LS174T colorectal carcinoma, and U373, U87, and MG-1 glioblastomas. For the in vivo studies of immunotoxins and liposomal monensin, BALB/c nu/nu mice were inoculated intraperitoneally with H-MESO-1 cells. RESULTS: Liposomal monensin potentiated the cytotoxic action of cell-specific anti-human transferrin receptor immunotoxin on H-MESO-1 target cells at a molar concentration of monensin that was 160-fold lower than the concentration of monensin in buffer that produced the same effect (0.3 nM versus 0.05 microM). Moreover, immunotoxin plus 0.1 microM liposomal monensin was fivefold more toxic for H-MESO-1 cells and 1000-fold and 2200-fold more toxic for human glioblastoma U373 and U87 cells, respectively, than immunotoxin plus 0.1 microM free monensin in buffer. Liposomal monensin produced similar effects when it was combined with different specific immunotoxins and other target cell lines (i.e., LS174T, U87, and CEM). Immunotoxin specificity was preserved with liposomal monensin, as shown by the absence of effect with non-cell-binding immunotoxins or on antigen-negative cell lines. In mice, liposomal monensin in combination with specific immunotoxin substantially prolonged survival, and three (21%) of 14 mice bearing H-MESO-1 xenografts treated with the liposomes showed no evidence of tumor at day 160 after treatment. Treatment with control immunotoxin plus liposomal monensin was ineffective. CONCLUSION: These findings suggest that encapsulation of monensin into liposomes increased the capacity of monensin to enhance the potency of cell-specific immunotoxin in vitro and in vivo.

Automatic matching of spine images to assess changes in scoliosis.

This paper presents an image matching approach that can be used to measure changes in scoliotic curves. The proposed approach uses a novel fuzzy logic controller to estimate all open parameters. Using fluoroscopy images of a spine phantom, it was found that, with minimal user interaction, the matching of spine images could be achieved with high accuracy (the average errors were around 0.03 mm) and high computational efficiency (requiring less than 1 minute for matching each vertebra).

Evaluating similarity metrics in an image matching tool for image guided spine surgery.

This paper presents a comparison study of the effect of three similarity measures (mutual information, normalized mutual information, and mean squared error on the edges of the input image) in an image matching tool that can be used in image guided spine surgery. Using 3D rotational x-rays and magnetic resonance images of a spine phantom, it was found that the similarity measures had similar effect. Therefore, experiments with other datasets are needed before making conclusions about the suitability of these similarity metrics for image guided surgery.

Intra-operative spinal load and displacement monitoring: towards a better understanding of scoliosis correction mechanics.

Surgical correction of scoliosis reduces deformation and improves overall function and esthetics. Understanding and monitoring of mechanics during scoliosis surgery is an invaluable tool to optimize correction without compromising patient safety. Our objective was to use intra-operative monitoring tools to study how spinal load and displacement relates to obtained correction and chosen instrumentation. Instrumented pedicle screws, a "gripper" and active markers were developed. Instrumented pedicle screws provided three-dimensional forces at the screw-vertebra interface while the instrumented "gripper" measured the force and the rotation applied by the surgeon to the rod rotator. Vertebral displacement was monitored with light-emitting diodes and motion capture technology. These instruments were used successfully with 16 scoliosis subjects. Analysis of applied force, displacement, and curve flexibility influence on correction percentage is the long term goal. Raw results for instrumented screws and gripper showed that recorded force decreased with respect to percentage of correction obtained. Measured force increased with respect to the pre-surgical Cobb angle while percentage of correction obtained decreased as pre-surgical Cobb angle increased. Active marker results showed three-dimensional vertebral rotation and translation during correction, with axial rotation and caudal-cranial translation having the greatest magnitudes. Using greater correction forces does not necessarily result in an increased correction; flexibility and Cobb angle also play a role in the mechanics of correction. Further data collection will provide better understanding of the interconnected role between these factors helping complete the description of surgery mechanics.

Radioimmunoassay for the detection and quantitation of 5-fluorodexoyuridine.

A sensitive radioimmunoassay for 5-fluorodeoxyuridine (FdUrd) and 5-fluoro-2'-deoxyuridine 5'-monophosphate has been developed by using antibody induced in rabbits, [3H]FdUrd, and a separation technique with nitrocellulose filters. Antibody specificity was characterized by using compounds chemically related to FdUrd and comparing their effectiveness for displacing [3H]FdUrd from the antibody-combining site. Drug levels in serum samples from patients receiving FdUrd chemotherapy were easily and rapidly determined, and the serum disappearance of the drug was followed by this method. FdUrd was also detected and quantified in urine samples. According to the antiserum used, as little as 1 to 10 pmol FdUrd were measurable.

Monensin in lipid emulsion for the potentiation of ricin A chain immunotoxins.

The utilization of carboxylic ionophores such as monensin for immunotoxin potentiation may be hampered by the poor solubility and short in vivo half-life of these highly lipophilic compounds. Therefore, the use of monensin formulated in a lipid/water emulsion was investigated for the in vitro and in vivo potentiation of immunotoxins. Monensin in emulsion or in buffer was equally effective for the in vitro potentiation of the cytotoxicity of both anti-human transferrin receptor and anti-carcinoembryonic antigen immunotoxins against target cells. In mice, buffer and lipid emulsion were compared as vehicles for the i.p. administration of monensin. The half-life of monensin in the peritoneal cavity of BALB/c x DBA/2 F1 (CD2F1) mice was increased 20-fold by inclusion in lipid emulsion (13 min versus 0.75 min). Treatment i.p. with anti-human transferrin receptor immunotoxin or anti-carcinoembryonic antigen immunotoxin and monensin emulsion prolonged the survival of mice with macroscopic i.p. tumor xenografts of H-Meso-1 mesothelioma and LS174T colorectal carcinoma (200-250% increased length of median survival). The in vivo antitumor effect of the cell-specific immunotoxin plus monensin emulsion was superior to immunotoxin alone or to immunotoxin plus monensin in buffer (P less than 0.03; Mann-Whitney U test). This indicates that delivery of monensin in preformed lipid emulsion may produce a reservoir effect of the ionophore in the peritoneal cavity of tumor-bearing mice. Nonspecific control immunotoxin plus monensin emulsion produced no increase in survival. Long-term tumor-free survival (greater than 150 days versus a median survival of 25 days for controls) of mice bearing microscopic LS174T xenografts was obtained by treatment with anti-human transferrin receptor immunotoxin plus monensin emulsion. Administration of either monensin in buffer or monensin in emulsion without immunotoxin had no significant effect on survival. Monensin in this pharmacologically available form significantly improved the in vivo efficacy of both anti-human transferrin receptor immunotoxin and anti-carcinoembryonic antigen immunotoxin when used as regional therapy.

A rapid and specific radioimmunoassay for methotrexate.

A sensitive and precise radioimmunoassay for methotrexate has been developed using antibody induced in rabbits, tritium-labeled methotrexate, and a nitrocellulose membrane separation technique. Antibody specificity was characterized by comparing the effectiveness of various related compounds to displace labeled methotrexate from the antibody-binding site. Assay of serum samples from persons receiving the drug was rapid and easy to perform. In a pharmacokinetic study of methotrexate, corresponding results were obtained when measurements were made by either enzymic assay or by radioimmunoassay. Drug concentrations could also be monitored in the cerebrospinal fluid and urine of patients on high-dose methotrexate therapy followed by citrovorum factor rescue. The system measured a little as 0.1 to 1 pmole of methotrexate, depending upon the antiserum used, and naturally occurring folates did not interfere with these determinations.

Hybrid antibodies with dual specificity for the delivery of ricin to immunoglobulin-bearing target cells.

Hybrid antibodies possessing one binding site for the toxic lectin ricin and a companion site directed against human immunoglobulin were constructed in vitro. This bifunctional reagent specifically attached to human lymphocyte surface immunoglobulin determinants and, thus situated, could simultaneously capture ricin molecules or its toxic A chain. Attachment of these components to the cell was revealed by specific fluorescein-labeled antibodies. Once concentrated at the target cell membrane, hybrid-bound toxin was subsequently released to function via its normal mechanism of biological action. It gained access to ribosomes, its intracellular target, and curtailed protein synthesis. Toxicity was not augmented for immunoglobulin-negative cells to which hybrid could not bind and free human immunoglobulin G could competitively block the enhanced effects observed for immunoglobulin-bearing cell lines. These results indicate that hybrid antibodies may be utilized to carry active agents within close proximity to the membrane of a specified cell type and thereby selectively enhance their effect.

Radioimmunoassay of neocarzinostatin, an antitumor protein.

Antibodies directed toward the antitumor protein neocarzinostatin (NCS) have been produced in a rabbit by immunization with a highly purified NCS preparation. The antiserum was monospecific and reversed the antibacterial activity of NCS against Sarcina lutea. It cross-reacted with chemically modified derivatives of NCS and mitomalcin but failed to cross-react with macromomycin. A radioimmunoassay procedure has been developed utilizing the antiserum and a biologically active 125I-labeled derivative of NCS. The lower limit of detection by this radioimmunoassay, which involves a double antibody technique for the separation of antibody-bound and free antigen, was 1 X 10(-13) mole. The sensitivity of the assay is such that serum levels of NCS can be determined accurately after administration of the drug to rats at a single dose of 2 mg/kg. Since NCS is now undergoing clinical trial, the radioimmunoassay of the drug will be a valuable tool in clinical pharmacological studies.

In vitro inhibition of human leukemic cells (CCRF-CEM) by agarose-immobilized neocarzinostatin.

Neocarzinostatin (NCS) is an acidic protein (molecular weight, 10,700) isolated from Streptomyces carzinostaticus that has antitumor activity both in model rodent systems and in humans. In vitro it inhibits the growth of a human lymphoblastic leukemic cell line (CCRF-CEM) at a very low concentration (the amount of drug that causes a 50% inhibition of growth compared to control cultures as extrapolated from a dose-response curve (ID50), 2.4 X 10(-9) M). We covalently coupled NCS to the N-hydroxysuccinimide ester of agarose and obtained a product that, by a variety of biochemical and immunological criteria, has been demonstrated to be devoid of any free or loosely bound NCS. Agarose-bound NCS, which is unable to enter cells because of its size, retains a significant amount of inhibitory activity (ID50, 6 to 15 X 10(-9) M) and is also capable of inhibiting tritiated deoxythymidine incorporation into CCRF-CEM cells. Since agarose-bound NCS cannot enter mammalian cells, the above findings indicate that NCS is able to exert its toxic effects by binding to or reacting with receptors on the cell membrane.