Design and evaluation of a device for measuring three-dimensional micromotions of press-fit femoral stem prostheses

Implant micromotion is considered to be a major factor in the loosening of cementless total hip replacements. Translational micromotion at the bone-implant interface generally occurs in all three spatial directions. Under physiological loading, the interfacial micromotion consists of a cyclic amplitude and changes in the mean, which, in the cranio-caudal direction, represents subsidence of the prosthesis. Existing measurement strategies, which are based on dial gauges, extensometers, LVDTs, hall-effect transducers or strain gauge techniques provide information about only one component of the general three-dimensional micromovement. Moreover, in the majority of the studies, the data are difficult to interpret due to the measured motions being composed of interfacial micromotion and femoral strains. A new transducer was designed that allows the accurate measurement of all three isolated components of micromotion. An optoelectronic approach, based on silicon position-sensitive detectors (PSD) in combination with high precision mechanical parts, was chosen. To exclude thermodrifts during long-term testing, a thermistor was integrated in the sensor. Validation experiments on a precision positioning table indicated the high precision and resolution of the developed sensors. Furthermore, in-vitro tests on a standard press-fit prosthesis demonstrated the easy handling and reliability of the system.     

Expression of an antigen homologous to the human CO17-1A/GA733 colon cancer antigen in animal tissues

The CO17-1A/GA733 antigen is associated with human carcinomas and some normal epithelial tissues. This antigen has shown promise as a target in approaches to passive and active immunotherapy of colorectal cancer. The relevance of animal models for studies of immunotherapy targeting this antigen in patients is dependent on the expression of the antigen on normal animal tissues. Immunohistoperoxidase staining with polyclonal rabbit antibodies to the human antigen revealed the human homologue on normal small intestine, colon and liver of mice, rats and non-human primates, whereas mouse monoclonal antibodies to the CO17-1A or GA733 epitopes on the human antigen did not detect the antigen. Polyclonal rabbit antibodies, elicited by the murine antigen homologue derived from recombinant baculovirus-infected insect cells, immunoprecipitated the antigen from mouse small intestine, colon, stomach, kidney and lung. The isolated recombinant murine protein bound polyclonal, but not monoclonal, antibodies to the human CO17-1A/GA733 antigen, and recombinant human antigen bound polyclonal antibodies elicited by the murine antigen homologue. Thus, the antigen homologue expressed by animal tissues is similar, but not identical, to the human antigen. These results have important implications for experimental active and passive immunotherapy targeting the CO17-1A/GA733 antigen.     

Activity of oxidation-reduction enzymes in endotheliocytes of the intestinal hemomicrocirculatory bed under normal conditions and in portal hypertension

An original quantitative examination of oxidation-reduction enzymes activity in endotheliocytes of hemomicroclrculatory vessels of jejunum and rectum submucosal base in normal state and in portal hypertension was performed by the authors. Comparative analysis of the activity of the enzymes studied revealed different metabolic processes intensity in these organs, dependent on current hemodynamic conditions. Cytochemical changes in hemomicrocirculatory bed are consistent with structural reorganizations that arise in the wall of vessels studied, consist of several phases and may be used as an assessment criterion for defining the portal hypertension stage.     

Relationships between left hemisphere predominance and disturbances of lipid metabolism in different ethnic groups

In neonates and infants, hearing impairment leads to impaired language and cognitive development. For that reason, early detection of this sensory deficit is of outstanding importance, particularly in pre-term neonates, who constitute a high risk population in regard to very early acquired hearing loss. Evoked (EOAE) and spontaneous otoacoustic emission (SOAE) recording in 93 pre-term and full-term neonates revealed that this technique is potentially useful for auditory screening in neonatology units. EOAEs and SOAEs can be recorded successfully from 30 weeks of conceptional age. SOAEs were found to be prevalent in females and presented higher peak numbers in right than in left ears. Furthermore, SOAE incidence in pre-term and full-term neonates was found to be high in EOAE positive ears, associated with strong and robust EOAEs.     

Contribution of rpoB mutations to development of rifamycin cross-resistance in Mycobacterium tuberculosis

The contributions of 23 insertion, deletion, or missense mutations within an 81-bp fragment of rpoB, the gene encoding the beta-subunit of the DNA-dependent RNA polymerase of Mycobacterium tuberculosis, to the development of resistance to rifamycins (rifampin, rifabutin, rifapentine, and KRM-1648) in 29 rifampin-resistant clinical isolates were defined. Specific mutant rpoB alleles led to the development of cross-resistance to all rifamycins tested, while a subset of mutations were associated with resistance to rifampin and rifapentine but not to KRM-1648 or rifabutin. To further study the impact of specific rpoB mutant alleles on the development of rifamycin resistance, mutations were incorporated into the rpoB gene of M. tuberculosis H37Rv, contained on a mycobacterial shuttle plasmid, by in vitro mutagenesis. Recombinant M. tuberculosis clones containing plasmids with specific mutations in either codon 531 or 526 of rpoB exhibited high-level resistance to all rifamycins tested, whereas clones containing a plasmid with a mutation in codon 516 exhibited high-level resistance to rifampin and rifapentine but were susceptible to both rifabutin and KRM-1648. These results provided additional proof of the association of specific rpoB mutations with the development of rifamycin resistance and corroborate previous reports of the usefulness of rpoB genotyping for predicting rifamycin-resistant phenotypes.     

Three-dimensional solution structure of alpha-conotoxin MII by NMR spectroscopy: effects of solution environment on helicity

alpha-Conotoxin MII, a 16-residue polypeptide from the venom of the piscivorous cone snail Conus magus, is a potent and highly specific blocker of mammalian neuronal nicotinic acetylcholine receptors composed of alpha3 beta2 subunits. The role of this receptor type in the modulation of neurotransmitter release and its relevance to the problems of addiction and psychosis emphasize the importance of a structural understanding of the mode of interaction of MII with the alpha3 beta2 interface. Here we describe the three-dimensional solution structure of MII determined using 2D 1H NMR spectroscopy. Structural restraints consisting of 376 interproton distances inferred from NOEs and 12 dihedral restraints derived from spin-spin coupling constants were used as input for simulated annealing calculations and energy minimization in the program X-PLOR. The final set of 20 structures is exceptionally well-defined with mean pairwise rms differences over the whole molecule of 0.07 A for the backbone atoms and 0.34 A for all heavy atoms. MII adopts a compact structure incorporating a central segment of alpha-helix and beta-turns at the N- and C-termini. The molecule is stabilized by two disulfide bonds, which provide cross-links between the N-terminus and both the middle and C-terminus of the structure. The susceptibility of the structure to conformational change was examined using several different solvent conditions. While the global fold of MII remains the same, the structure is stabilized in a more hydrophobic environment provided by the addition of acetonitrile or trifluoroethanol to the aqueous solution. The distribution of amino acid side chains in MII creates distinct hydrophobic and polar patches on its surface that may be important for the specific interaction with the alpha3beta2 neuronal nAChR. A comparison of the structure of MII with other neuronal-specific alpha-conotoxins provides insights into their mode of interaction with these receptors.     

Financial effect of clinical decisions: case study of a dialysis center

This paper explores, in the isolated guinea-pig ileum, the effects of temperature on the acute development of opioid dependence and on the precipitation of the abstinence response, using as reference the effect of temperature on the response to a standard nicotine concentration. Additionally, the influence of temperature on acute morphine neurodepression was examined. Three experimental groups were included. In the first, the bath temperature was adjusted and maintained along the experimental session (2.5 h) at one of the following values: 28, 32, 36 or 40 degrees C. In the second, the different values of bath temperature were applied only during the period of morphine exposure before testing the abstinence response at 36 degrees C. In the third, all segments were initially incubated at 36 degrees C for 1 h, and afterwards, abstinence and the nicotine response were elicited at the different temperatures mentioned. In all the series, a single challenge naloxone dose (3.1, 10, 31, 100, 316, 1000 or 3160 nM) was administered after 1h of morphine and complete naloxone concentration-response curves were obtained. The abstinence response was expressed as a percentage of the nicotine reference response. All segments showed robust nicotine responses at all the experimental protocols tested indicating that, at the temperature range studied, the contractile mechanisms were impaired. This study showed that changes in bath temperature modify the magnitude of acute morphine neurodepression, and of the abstinence response but did no affect the development of acute opioid dependence. These data, along with several lines of evidence, strongly suggest that acute neurodepression, the development of opiate dependence and antagonist-precipitated abstinence are separable. Results are discussed on the basis of drug-receptor interactions.     

Differing haemodynamic and catecholamine responses to exercise in three groups with peripheralautonomic dysfunction: insulin-dependent diabetes mellitus, familial amyloid polyneuropathy and pure autonomic failure

BACKGROUND: The nosological status of postpartum psychoses has remained controversial because of their often 'atypical' symptomatology. A polydiagnostic approach may further clarify this issue. METHODS: In a retrospective study, we applied the ICD-10 and Leonhard's classification to 39 patients with severe postpartum psychiatric disorders. The patients were personally reexamined on average 12.5 years (6-26 years) after the onset of the illness. RESULTS: An acute onset and a polymorphous psychotic symptomatology with rapid changes characterized the majority of our cases. Unipolar depressive disorders (28%) and acute polymorphous psychotic disorders (21%) represented the largest proportions within the ICD-10-classification. Applying Leonhard's classification, over half the patients (54%) suffered from a cycloid psychosis. Among cycloid psychoses, motility psychoses clearly predominated. Schizophrenias occurred rarely (10%) according to both classifications. LIMITATIONS: Due to the unknown prevalence of the various diagnoses among women of child-bearing age, it is impossible to statistically infer a specific association between childbirth and a distinct diagnosis from our data. CONCLUSIONS: Our findings suggest that cycloid psychoses, in particular motility psychoses, account for the majority of postpartum psychoses, and do not support the hypothesis of a nosological independence of postpartum psychoses.     

Digital wavelet-encoded MRI: a new wavelet-encoding methodology

A new digital wavelet-encoding method for MRI is described. The method differs from previously described wavelet-encoding approaches, because the point-spread function is made independent of the wavelet basis used. This has a significant practical advantage, because wavelet bases can now be considered that would otherwise be excluded due to the difficulty of precisely exciting wavelet-shaped RF profiles. The method has been implemented on a clinical MRI system, and human images are presented.