Biochemical characterization of LR769, a new recombinant factor VIIa bypassing agent produced in the milk of transgenic rabbits

BACKGROUND

The bypassing agent factor VII (FVIIa) is a first-line therapy for the treatment of acute bleeding episodes in patients with haemophilia and high-titre inhibitors. FVIIa is a highly post-translationally modified protein that requires eukaryotic expression systems to produce a fully active molecule. A recombinant FVIIa was produced in the milk of transgenic rabbits to increase expression and provide an efficient, safe and affordable product after purification to homogeneity (LR769).

AIM

To present the biochemical and functional in vitro characteristics of LR769.

RESULTS

Mass spectrometric analyses of the intact protein and of heavy and light chains revealed a fully activated, mature and properly post-translationally modified protein notably regarding N/O-glycosylations and γ-carboxylation. Primary structure analysis, performed by peptide mapping, confirmed 100% of the sequence and the low level or absence of product-derived impurities such as oxidized, deamidated and glycated forms. Low levels of aggregates and fragments were observed by different chromatographic methods. Higher order structure investigated by circular dichroism showed appropriate secondary/tertiary structures and conformational change in the presence of Ca²⁺ ions. Finally, activated partial thromboplastin time and thrombin generation assays showed the ability of LR769 to decrease coagulation time and to generate thrombin in haemophiliac-A-plasmas, even in the presence of inhibitors.

CONCLUSION

The innovative expression system used to produce LR769 yields a new safe and effective rhFVIIa for the treatment of haemophilia A or B patients with inhibitors.

Genetic diversity of 38 insertion-deletion polymorphisms in Jewish populations

Population genetic data of 38 non-coding biallelic autosomal indels are reported for 466 individuals, representing six populations with Jewish ancestry (Ashkenazim, Mizrahim, Sephardim, North African, Chuetas and Bragança crypto-Jews). Intra-population diversity and forensic parameters values showed that this set of indels was highly informative for forensic applications in the Jewish populations studied. Genetic distance analysis demonstrated that this set of markers efficiently separates populations from different continents, but does not seem effective for molecular anthropology studies in Mediterranean region. Finally, it is important to highlight that although the genetic distances between Jewish populations were small, significant differences were observed for Chuetas and Bragança Jews, and therefore, specific databases must be used for these populations.

New data on Perkinsus mediterraneus in the Balearic Archipelago: locations and affected species

Perkinsus mediterraneus, a protozoan parasite that can cause perkinsosis (marine mollusc disease), was first detected in oysters Ostrea edulis from Mahon (Minorca, Balearic Islands, Spain) in 2004. Several years later it was also found in Andratx Harbour (Majorca, Balearic Islands) and in the Gulf of Manfredonia (Adriatic coast of Italy) in oyster populations. Since 2007, Perkinsus surveys have been conducted in different localities and shellfish species in the Balearic Archipelago. In the present work, we found P. mediterraneus in the Balearic Islands infecting oyster and other shellfish species. We describe infection with P. mediterraneus for the first time in Arca noae and Mimachlamys varia. The detection was carried out using Ray's fluid thioglycolate medium (RFTM), histology and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodologies. The internal transcribed spacer (ITS) region (including ITS1, 5.8S and ITS2) of P. mediterraneus ribosomal DNA was sequenced from infected bivalve gills (or from the body in Chamelea gallina) from Balearic Archipelago localities. Twelve haplotypes with a strong genetic similarity between them (97-100%) were observed in our samples. These data were completed with 12 more haplotypes from GenBank sequences. The phylogenetic relationship between Balearic P. mediterraneus haplotypes found in this study, those previously obtained in Mahon Harbour, and the Perkinsus spp. sequences available in GenBank clearly grouped the different Perkinsus spp. in distinct clades supported by strong bootstrap values. Moreover, these analyses detected different P. mediterraneus groups in O. edulis from Minorca Island. No abnormal mortalities or decline in populations were detected during the survey, except for C. gallina, which is also affected by Marteilia refringens.

Thermal parameters measurement on fire fighter: improvement of the monitoring system

Real time monitoring of the thermal parameters on firefighter when operating is one of the ProeTEX project goals. The newly developed equipments in the framework of this project, integrate one temperature sensor and one heat flux sensor in the rescuer's outer garment. The environment in which firefighters operate is dangerous and the thermal risks can occur everywhere. Consequently the heat flux is so not necessarily symmetrical. To improve the thermally at risk situation detection, a modified platinum sensors array was integrated in the jacket in order to monitor simultaneously heat flux and temperature surrounding the rescuer. The sensors were placed in the most exposed area (shoulders and chest) to monitor thermal parameter in different directions. The heat flux is calculated from the temperature difference. This sensors array enables the detection of temperature increases and heat flux even when the heat source is localized on one side.

An integrated platform to assess driver's physiological and functional states

Physiological signals like Heart Rate, Respiration and Skin Resistance are relevant indicators to evaluate driver's mental state. Therefore, most methods based on physiological signals measurements have been improved on driving simulators or in experimental laboratories under carefully controlled conditions and rigorous protocols. To study driver's behavior in actual conditions, we have developed an in-vehicle system which could record contextual driving information, drivers' actions and physiological signals related to them. Recordings from the driver and the vehicle may give valuable information for a close estimation of driver's functional state, its evolution across time and thus a better understanding of driver's behavior. This system provides specific patterns related to the driver's functional state, according to the driving context. This paper is aimed to present the design and implementation of this system, well adapted to ergonomics.

Power spectral density changes and language lateralization during covert object naming tasks measured with high-density EEG recordings

Our objective was to study changes in EEG time-domain power spectral density (PSDt) and localization of language areas during covert object naming tasks in human subjects with epilepsy. EEG data for subjects with epilepsy were acquired during the covert object naming tasks using a net of 256 electrodes. The trials required each subject to provide the names of common objects presented every 4 seconds on slides. Each trial comprised the 1.0 second before and 3.0 seconds after initial object presentation. PSDt values at baseline and during tasks were calculated in the theta, alpha, beta, low gamma, and high gamma bands. The spatial contour plots reveal that PSDt values during object naming were 10-20% higher than the baseline values for different bands. Language was lateralized to left frontal or temporal areas. In all cases, the Wada test disclosed language lateralization to the left hemisphere as well.

Interface pressure monitoring for a secured instrumented childbirth

Complications in forceps deliveries are rare but their consequences might be dramatics. This situation could be avoided if the obstetrician knows the information concerning symmetry of the obstetrical forceps position on the fetal head and the related interface pressure. Indeed, forceps delivery is an emergency gesture which is normally not expected. Our purpose is to determinate relevant parameters for a fast decision-making without any danger for the fetus. We have developed a new interface pressure measurement system in order to study pressure distribution of human body whatever its support (forceps, chair, bed...). This method has been adapted to measure the interface pressure between the fetal head and the forceps. This new system also provides information of forceps position symmetries. The aims of this system are: first, to prevent instrumented delivery accidents. Secondly, to provide a safe training of forceps technique. This paper presents results about experiments performed on phantoms of fetal head. Different forceps positions on phantom have been tested according to the classification of forceps application as per A.C.O.G 1981 (revised in 1991). These experiments have lead to the definition of relevant parameters in order to help the physician to validate the forceps positions before extraction.

FOR SAFE: instrumented and secured obstetrical forceps

Operative vaginal deliveries represent a significant amount of vaginal deliveries. Operative delivery involves either forceps either vacuum extraction. Complications are frequent but rarely severe (cutaneaous lesions, facial palsy...). However, it is essential to limit these complications by helping the obstetrician to position his extraction instrument. It is the aim of the FOR SAFE device: provide a new instrumented forceps which performs the interface pressure measurement between the fetal head and the shanks of the forceps. Interface pressure evaluation requires interaction between the living tissue and the sensor, just like a man needs to touch an object with its fingertip to evaluate its compliance. The design of the sensor is "bio inspired". The sensor interacts with the matter, without modifying phenomenon to be measured.

Multimodal imaging of somatosensory evoked cortical activity

Somatosensory evoked cortical activity is well investigated in both fMRI and MEG/EEG. Investigation with functional magnetic resonance spectroscopic (fMRS) imaging is relatively new and provides a means to image the metabolic activity of the brain. We for the first time combined fMRS, fMRI, MEG and EEG. This provides information about the metabolic, hemodynamic and electrical activity of the brain and also the verification of one imaging modality with the other. The dipolar source localized from the EEG/MEG data is in the vicinity of the fMRI activation site and also in the same area where lactate consumption is high as measured with fMRS imaging.

Effect of model complexity on EEG source localizations

How model complexity influences the EEG source localizations was studied with three different finite element models of the head, constructed from segmented MR images of an adult male subject. The complexity of the models varied from 9 to 11 tissue types. The lead fields due to dipolar sources in the motor cortex were computed for all three models. The inverse source localizations were performed with an exhaustive search pattern in the motor cortex area. A set of 100 trial inverse runs was made. It was found that the model with most complexity performed best in localizing the sources in the motor cortex area of the brain.

The influence of brain tissue anisotropy on human EEG and MEG

The influence of gray and white matter tissue anisotropy on the human electroencephalogram (EEG) and magnetoencephalogram (MEG) was examined with a high resolution finite element model of the head of an adult male subject. The conductivity tensor data for gray and white matter were estimated from magnetic resonance diffusion tensor imaging. Simulations were carried out with single dipoles or small extended sources in the cortical gray matter. The inclusion of anisotropic volume conduction in the brain was found to have a minor influence on the topology of EEG and MEG (and hence source localization). We found a major influence on the amplitude of EEG and MEG (and hence source strength estimation) due to the change in conductivity and the inclusion of anisotropy. We expect that inclusion of tissue anisotropy information will improve source estimation procedures.

The influence of local tissue conductivity changes on the magnetoencephalogram and the electroencephalogram

We examined the influence of local tissue conductivity changes in the vicinity of a dipolar source on the neuromagnetic field and the electric scalp potential using a high resolution finite element method model of the human head. We found that the topology of both the electric scalp potential and the neuromagnetic field (and consequently dipole localization) is influenced significantly by conductivity changes only in voxels adjacent to the source. Conductivity changes in these voxels yield a greater change in the amplitude of the magnetic field (and consequently in the dipole strength) than in the amplitude of the electric potential.

Effect of myocardial anisotropy on the torso current flow patterns, potentials and magnetic fields

The effects of myocardial anisotropy on the torso current flow patterns, voltage and the magnetic field were examined using an anatomically realistic torso model of an adult male subject. A finite element model of the torso was built with 19 major tissue types identified. The myocardial fibre orientation in the heart wall was included with a voxel resolution of 0.078 x 0.078 x 0.3 cm. The fibre orientations from the canine heart which are available in the literature were mapped to our adult male subject's human heart using deformable mapping techniques. The current and potential distribution in the whole torso were computed using an idealized dipolar source of +/-1.0 V in the middle of the septum of the heart wall as a boundary condition. An adaptive finite element solver was used. Two cases were studied. In one case the myocardium was isotropic and in the other it was anisotropic. It was found that the current density distribution shows a very noticeable difference between the isotropic and anisotropic myocardium. The resultant magnetic field in front of the torso was computed using the Biot-Savart law. It was found that the magnetic field profile was slightly affected by the myocardial anisotropy. The potential on the torso surface also shows noticeable changes due to the myocardial anisotropy.

Cardiac biomagnetic source estimation with a heart-torso model and a trained neural network

The intensity of the cardiac sources for normal adult subjects was estimated from given magnetic field profiles with a trained neural network based on the relationship of the electrical activity of the heart to the cardiac magnetic fields. The input for training the neural network consisted of the magnetic field profiles above the torso during the heartbeat. The outputs were the dipole intensities which produced those magnetic field profiles. A back propagating algorithm with bias and momentum was utilized for training. The measured and simulated torso magnetic field profiles and magnetocardiograms were used for training the neural network. Estimation of the dipole intensities was performed for unknown magnetic field profiles with the trained neural network. The estimated cardiac dipole intensities were reasonably close to the true dipole intensities. These results show the feasibility of the estimation of cardiac dipole intensities with a trained neural network under a very restricted forward model of the cardiac magnetic fields. Generalization of the results to cover a large population base could be difficult because the activation isochrones are different from subject to subject.

MCG simulations of myocardial infarctions with a realistic heart-torso model

Data from simulations of the anterior myocardial infarction (AMI) and inferior myocardial infarction (IMI) are presented. One infarct located in the anterior section of the left ventricle and a second one in the inferior wall of the left ventricle were modeled. A high-resolution finite element model of a heart and torso was used in this study. Differences in the normal and infarcted fields were computed. Our data suggest that the infarcted region contribution to the total magnetic field can be accounted for by an equivalent current dipole. It might also be possible to detect an infarct from these difference fields constructed for different cases of myocardial infarction. More simulations are needed to determine the relations between infarct sizes and locations and magnetic fields. These relations might then be used to detect various cases of myocardial infarction.

MCG simulations with a realistic heart-torso model

Magnetocardiograms (MCG's) simulated with a high-resolution heart-torso model of an adult subject were compared with measured MCG's acquired from the same individual. An exact match of the measured and simulated MCG's was not found due to the uncertainties in tissue conductivities and cardiac source positions. However, general features of the measured MCG's were reasonably represented by the simulated data for most, but not all of the channels. This suggests that the model accounts for the most important mechanisms underlying the genesis of MCG's and may be useful for cardiac magnetic field modeling under normal and diseased states. MCG's were simulated with a realistic finite-element heart-torso model constructed from segmented magnetic resonance images with 19 different tissue types identified. A finite-element model was developed from the segmented images. The model consists of 2.51 million brick-shaped elements and 2.58 million nodes, and has a voxel resolution of 1.56 x 1.56 x 3 mm. Current distributions inside the torso and the magnetic fields and MCG's at the gradiometer coil locations were computed. MCG's were measured with a Philips twin Dewar first-order gradiometer SQUID-system consisting of 31 channels in one tank and 19 channels in the other.

Combination of capillary electrophoresis and matrix-assisted laser desorption ionization mass spectrometry for glycosylation analysis of a human monoclonal anti-Rhesus(D) antibody

Characterization of a human anti-Rhesus(D) monoclonal antibody, developed for the treatment of Rh(D) haemolytic disease of the newborn, was performed. Capillary electrophoresis (CE) has been employed for peptide mapping of the IgG heavy chain and glycopeptide identification. The combination of the high resolution and low solvent consumption of CE and the ultrasensitive detection and precise identification properties of mass spectrometry led to a complete glycosylation analysis of the protein. Glycopeptides were easily isolated from a single injection in a 100 microns i.d. capillary of the preparative CE system and collected for molecular mass determination using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The off-line CE-MS characterization revealed the presence of different oligosaccharides linked to the unique N297-S-T glycosylation site of the IgG heavy chain. The differences between calculated and experimental masses of the glycopeptides suggested the presence of a fucosylated biantennary structure containing one or two galactose units as major oligosaccharide, together with similar species bearing a bisecting N-acetylglucosamine. CE conditions were optimized to allow the MS identification of sialylated forms.

Influence of tissue resistivities on neuromagnetic fields and electric potentials studied with a finite element model of the head

Modeling in magnetoencephalography (MEG) and electroencephalography (EEG) requires knowledge of the in vivo tissue resistivities of the head. The aim of this paper is to examine the influence of tissue resistivity changes on the neuromagnetic field and the electric scalp potential. A high-resolution finite element method (FEM) model (452,162 elements, 2-mm resolution) of the human head with 13 different tissue types is employed for this purpose. Our main finding was that the magnetic fields are sensitive to changes in the tissue resistivity in the vicinity of the source. In comparison, the electric surface potentials are sensitive to changes in the tissue resistivity in the vicinity of the source and in the vicinity of the position of the electrodes. The magnitude (strength) of magnetic fields and electric surface potentials is strongly influenced by tissue resistivity changes, while the topography is not as strongly influenced. Therefore, an accurate modeling of magnetic field and electric potential strength requires accurate knowledge of tissue resistivities, while for source localization procedures this knowledge might not be a necessity.

Effects of tissue conductivity variations on the cardiac magnetic fields simulated with a realistic heart-torso model

Cardiac magnetic fields with varying tissue conductivities are simulated. A high-resolution finite-element torso model composed of 19 tissue types and with a voxel resolution of 1.5 mm x 1.5 mm x 3 mm is used. It has a detailed description of tissue geometries and therefore is well suited for analysing the effects of tissue conductivities on the cardiac magnetic fields. The computed results show the greatest sensitivity of the magnetic fields to the changes in the conductivity of blood and myocardium, and less significant sensitivity to the conductivity of the lungs, muscle, fat and other tissues. These results are relevant to future modelling of magnetocardiograms and solving the inverse problem. They also emphasize the importance of careful modelling of the blood and heart regions, and suggest that less attention needs to be directed to bone or fat tissue.

On the contribution of volume currents to the total magnetic field resulting from the heart excitation process: a simulation study

Data from a simulation study of volume current contribution to the total magnetic field produced in the heart excitation process is presented. Contributions from different tissue types are analyzed and effects of torso size are studied. A high resolution finite element model of an adult male torso composed of 19 tissue types is used. It has detailed description of tissue geometries and therefore is well suited for analyzing the contribution of the primary and secondary currents to the magnetic field. The computed results show major contribution of volume currents from blood, myocardium, and lungs and less significant contribution from liver, muscle, and other tissues. The contribution to the volume currents from the blood in the ventricles was highest. These simulations suggest that contribution to the total magnetic field due to volume currents flowing in tissues other than blood could be accounted for by simply multiplying the total field values by a constant. Values of these multipliers would be based on the tissue type and time in the excitation cycle. Effects of torso size on the computed magnetic fields are also evaluated. Our data shows that a torso extending approximately 3 cm above and below the heart produces field patterns similar to a larger torso model extending from top of guts to the bottom of neck. Thus a shorter torso model would be sufficient for cardiac magnetic field analysis. These results are of interest for future modeling of magnetocardiograms and solving the inverse problem.

On the influence of volume currents and extended sources on neuromagnetic fields: a simulation study

The influence of volume currents on the magnetic field is an important question in magnetoencephalography since the spherical volume conductor is still widely used for source localization. In theory, the magnetic field of a radial dipole in a homogeneous sphere is zero. In realistic models of the head, the field is suppressed when compared with a tangential dipole. To determine the influence of the volume currents, this suppression ratio (magnetic field of the radial dipole divided by the field of the tangential dipole) needs to be quantified. Large-scale finite element method models of the human head and the rabbit head were constructed and the suppression ratio was computed. The computed suppression value of 0.28 in the rabbit head was similar to the previously measured experimental value. In the human head, an average suppression ratio of 0.19 +/- 0.07 was found for different regions and depths in the gray matter. It was found that the computed magnetic field of radial sources varied significantly with the conductivities of the surrounding tissues where the dipole was located. We also modeled the magnetic field of an epileptic interictal spike in a finite element model of the rabbit head with a single dipole and with extended sources of varying length (1-8 mm). The extended source models developed were based on invasive measurements of an interictal spike within the rabbit brain. The field patterns of the small (1-2 mm) extended sources were similar to a single dipolar source and begin to deviate significantly from a dipolar field for the larger extended sources (6-8 mm).

Peptide mapping characterization by capillary electrophoresis of a human monoclonal anti-Rh(D) antibody produced for clinical study

CE has been employed for peptide mapping characterization of the light chain of a human anti-Rhesus (D) (Rh[D]) antibody presently undergoing clinical evaluation. In the presence of an ion-pairing agent used to increase resolution, reproducible maps were obtained within 55 min after injection of 12 fmol of protein. CE has also been employed as a direct and quick screening tool for purity evaluation of the tryptic peptides obtained from reversed-phase high-performance liquid chromatography (RP-HPLC) prior to sequence analysis. Post-translational modifications of the protein were determined by identification of the cysteine residues implicated in disulfide linkages.

Characterization of a recombinant antihaemophilia-A factor (factor VIII-delta II) by matrix-assisted laser desorption/ionization mass spectrometry

Factor VIII-delta II is a genetically engineered deletion variant of factor VIII, expressed by recombinant Chinese hamster ovary cells. This 1436-residues-long protein has a molecular mass, calculated from its sequence, of 164,954 Da and exhibits seven potential glycosylation sites. The glycoprotein, secreted as a single polypeptide chain, can be cleaved after Arg740 to generate a heavy-light chain complex of 90-80 kDa as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Due to its high mass range and excellent sensitivity, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has been chosen to play a key role in the precise determination of the molecular masses of recombinant factor VIII and the localization of the post-translational modifications within the protein. Native factor VIII-delta II displays a molecular mass of 178 kDa. The masses measured by MALDI for the heavy and light chains are respectively 89,900 Da and 87,100 Da. These mass values, found reproducible from batch to batch, are used to characterize factor VIII-delta II during the course of preclinical studies. The difference from the theoretical molecular molecular masses and the observation of broad molecular peaks suggest that recombinant FVIII-delta II has been effectively glycosylated by the host cell on both heavy and light chains. Similarly to plasma-derived factor VIII, the recombinant protein is proteolyzed by thrombin to generate the A1/A2/A3-C1-C2 trimer that is the active form of factor VIII in the coagulation pathway. MALDI-MS analysis of activated factor VIII-delta II suggested the presence of N-linked oligosaccharides in the proteolyzed light chain (A3-C1-C2 of 77,750 Da) and in the A1 domain (46,400 Da) of the heavy chain. By contrast, the similarity between the experimental and theoretical masses of the A2 domain indicated that its single potential glycosylation site has not been utilized.

Simulation studies of biomagnetic computed tomography

The reconstruction of planar and three-dimensional current distributions from measured biomagnetic signals is a new field of research, known as biomagnetic computed tomography. This noninvasive imaging technique promises to provide precise, millimeter-sized resolution images of the electrical currents in tissues or organs. We performed simulation studies on phantom models of electrical sources. As a first step towards the development of an imaging algorithm, we addressed a simplified problem to identify the shape and direction of current flow in a planar surface. The problem was formulated by identifying a space in which the image was to be reconstructed. The space was segmented into a grid. Each grid space represented a current element. The magnetic field at a sampling point due to the current elements was computed using the Biot-Savart law. Since there were many more current elements than sample points, the problem was undetermined and had an uncountable number of solutions. The projection theorem was used to define an analytic solution for the magnitude and orientation of the current elements in the grid space. The solution required the inversion of large matrices in double precision. Such arrays were preprocessed on a mainframe computer, which permitted them to be rendered on any workstation. The accuracy of the image was determined by comparing it with the known location of the sources. Our results show that shape of the filamentary current flow can be imaged with our techniques. The resolution of images based on the sampling of the field, number of voxels in the reconstruction space, and noise is also analyzed.

Resolution enhancement of biomagnetic images using the method of alternating protections

Resolution of biomagnetic images using the technique of the alternating projections is proposed. Our image reconstruction procedure is divided in two steps. First, the biomagnetic inverse problem is solved by use of the projection theorem to reconstruct an initial image of the current distribution from a given magnetic field profile. Although the current distribution thus obtained has poor resolution, it can resemble the original shape of the current distribution. The second step improves the resolution of the reconstructed image by using the method of alternating projections. The procedure assumes that images can be represented by line like elements and involves finding the line like elements based on the initial image and projecting back onto the original solution space. Simulation studies were performed on a set of parallel conductors and a shape of the conductors in the form of letters, UWB@. All conductors were of line like thickness. Restored images closely resemble the original shape of the conductors.

Preliminary report: modification of cardiac contraction rate by pulsed magnetic fields

Isolated rat hearts and excised canine cardiac tissues were subjected to pulsed magnetic fields. The fields excited in coils by tandem pairings of sinusoidal pulses were presented at various inter-pair delays and repetition rates. The waveform of the magnetic field was a single or multiple sinusoid followed after a variable delay by another single or multiple sinusoid. Small but reliable increases in the beating rate of rat heart were observed. Similar increases occurred in contraction rates of canine tissues. Both preparations exhibited a contraction-rate dependency on the repetition rate of the paired magnetic pulses: 4.5-6 rep/s for canine tissue, and 20-25 and 40-55 reps/s for rat heart. Flux-density thresholds for both preparations approximated 10 mT (100 gauss) rms.

Low-level, magnetic-field-induced growth modification of Bacillus subtilis

Experimental studies showed an increase in the growth of Bacillus subtilis mutant strain FJ7 above controls by exposing the bacterial culture to 800-Hz or 1-KHz magnetic fields with a 2-s-on/2-s-off period. The magnetic field strength was between 0.8 and 2.5 mT. Light microscopy and scanning electron microscopy demonstrated the morphology of controls to grow in a macrofiber of right-handed helix formation. In contrast, the field-exposed group showed little to no cohesion; the cells appeared to be homogeneously distributed throughout the sample. These results suggest that growth patterns of Bacillus subtilis can be altered as a result of magnetic-field-induced effects.

Muscle pathway geometry in the heart wall

Muscle fiber pathways in the heart wall are described. Procedures are introduced which permit data to be standardized from cadaver and animal hearts fixed at different points of the cardiac cycle or obtained in vivo from patients with different ejection fractions and heart masses. Design criteria are also developed here to construct a hypothetical standard left ventricle to compare the data from different hearts. The equations allow the nested set of toroidal fiber-shells to be depicted with typical muscle fiberpaths. With this formulation the heart wall and typical elements in it can be shown computergraphically as they move from the contracted state to the distended. Man-made fiber structures that simulate the fail-safe shockload absorbing features of the heart can now be designed and tested computergraphically by use of the mathematical procedures described here.

Inhibition of growth rate of Escherichia coli induced by extremely low-frequency weak magnetic fields

Cultures of Escherichia coli kept at 0 degree C in a phosphate buffer solution were exposed to a sinusoidal weak 60- or 600-Hz magnetic field of strength 2 X 10(-3) Tesla. A decrease of more than 40% in bacterial count was observed after a 60-h exposure to the magnetic field. Electron micrographs of exposed bacteria show ruptured cell walls, possibly due to the breaking away of flagella under the influence of the sinusoidally varying electromotive force.