Effects of a Prosthetic Foot With Increased Coronal Adaptability on Cross-Slope Walking.

BACKGROUND: Walking on cross-slopes is a common but challenging task for persons with lower limb amputation. The uneven ground and the resulting functional leg length discrepancy in this situation requires adaptability of both user and prosthesis. OBJECTIVES: This study investigated the effects of a novel prosthetic foot that offers adaptability on cross-slope surfaces, using instrumented gait analysis and patient-reported outcomes. Moreover, the results were compared with two common prosthetic feet. METHODOLOGY: Twelve individuals with unilateral transtibial amputation and ten able-bodied control subjects participated in this randomized cross-over study. Participants walked on level ground and ±10° inclined cross-slopes at a self-selected walking speed. There were three prosthetic foot interventions: Triton Side Flex (TSF), Triton LP and Pro-Flex LP. The accommodation time for each foot was at least 4 weeks. The main outcome measures were as follows: frontal plane adaptation of shoe and prosthetic foot keel, mediolateral course of the center of pressure, ground reaction force in vertical and mediolateral direction, external knee adduction moment, gait speed, stance phase duration, step length and step width. Patient-reported outcomes assessed were the Activities specific Balanced Confidence (ABC) Scale, Prosthetic Limb Users Survey of Mobility (PLUS M) and Activities of Daily Living Questionnaire (ADL-Q). FINDINGS: The TSF prosthetic foot adapted both faster and to a greater extent to the cross-slope conditions compared to the Triton LP and Pro-Flex LP. The graphs for the mediolateral center of pressure course and mediolateral ground reaction force showed a distinct grouping for level ground and ±10° cross-slopes, similar to control subjects. In the ADL-Q, participants reported a higher level of perceived safety and comfort when using the TSF on cross-slopes. Eight out of twelve participants preferred the TSF over the reference. CONCLUSIONS: The frontal plane adaptation characteristics of the TSF prosthetic foot appear to be beneficial to the user and thus may enhance locomotion on uneven ground - specifically on cross-slopes.

Simple interferometer for evanescent field refractive index sensing as a feasibility study for an immunosensor.

We describe a fiber optic interferometric refractive index sensor to illustrate that, by using the evanescent field of an optical waveguide, a potentially very sensitive determination of changes in the refractive index on the waveguide surface can be obtained. These changes can, e.g., be the result of immunoreactions. We used a Mach-Zehnder interferometer configuration with a flow-through cuvette in one arm with a decladded multimode glass fiber of 0.6-mm diameter and 2-cm interaction length. The obtained resolution in measuring refractive index changes is 1 x 10-(3). We also developed the theory describing the sensitivity of this sensor using the modal and the geometrical ray description.

Controlled and functional expression of the Pseudomonas oleovorans alkane utilizing system in Pseudomonas putida and Escherichia coli.

The OCT plasmid encodes enzymes for alkane hydroxylation and alkanol dehydrogenation. Structural components are encoded on the 7.5-kilobase pair alkBAC operon, whereas positive regulatory components are encoded by alkR. We have constructed plasmids containing fusions of cloned alkBAC and alkR DNA and used these fusion plasmids to study the functional expression of the alkBAC operon and the regulatory locus alkR in Pseudomonas putida and in Escherichia coli. Growth on alkanes requires a functional chromosomally encoded fatty acid degradation system in addition to the plasmid-borne alk system. While such a system is active in P. putida, it is active in E. coli only in fadR mutants in which fatty acid degradation enzymes are expressed constitutively. Using such mutants, we found that E. coli as well as P. putida grew on octane as the sole source of carbon and energy when they were supplied with the cloned complete alk system. The alkR locus was strictly necessary in E. coli as well as in P. putida for expression of the alkBAC operon. The alkBAC operon could, however, be further reduced to a 5-kilobase pair operon without affecting the Alk phenotype in either species to a significant extent. Although with this reduction the plasmid-encoded alkanol dehydrogenase activity was lost, chromosomally encoded alkanol dehydrogenases in P. putida and E. coli compensated for this loss. The induction kinetics of the alk system was studied in detail in P. putida and E. coli. We used specific antibodies raised against alkane hydroxylase to follow the appearance of this protein following induction with octane. We found the induction kinetics of alkane hydroxylase to be similar in both species. A steady-state level was reached after about 2 h of induction in which time the alkane hydroxylase accounted for about 1.5% of total newly synthesized protein. Thus, alkBAC expression is very efficient and strictly regulated to both P. putida and E. coli.

Ultrastructural study of rotavirus replication in cultured cells.

A systematic ultrastructural analysis of the replication cycle of the simian rotavirus SA11 in permissive MA104 cells was performed under reproducible conditions. At 8 h p.i., small areas of viroplasm were seen adjacent to swollen vesicles of the rough endoplasmic reticulum (rer) containing a few 80 to 90 nm virus particles. At later times, the size and number of these inclusions increased and the rer contained large numbers of the 80 to 90 nm particles as well as 52 to 65 nm particles. Infected cells eventually lysed, releasing progeny virus. Other cytological alterations included virus particles sequestered in lysosome-like bodies, 15 to 20 nm tubular structures in the nucleus and/or cytoplasm, convoluted membranes within the rer, filament bundles associated with virus particles, and mitochondria containing 1 to 5 virus particles. In addition, SA11 replication was studied in several less permissive cell lines. The results were similar to those with MA104 cells except that a smaller percentage of the cells were productively infected.

The use of prostaglandin E1 and Blalock-Taussig shunts in neonates with cyanotic congenital heart disease.

Six unselected neonates with cyanotic congenital heart disease and life-threatening degrees of arterial oxygen desaturation have been managed by a protocol that includes administration of prostaglandin E1 (PGE1) and early Blalock-Taussig shunting. In 5 patients (seven paired observations) partial pressure of arterial oxygen (PaO2) rose from 19 mm Hg to a mean of 32.9 mm Hg within 20 minutes of initiation of PGE1 (0.1 to 0.2 microgram/kg/hr), infused intravenously or through an aortic catheter placed at ductal level or with both methods. The nonresponsive patient was older than the patients showing a positive response (1 month versus 24 to 96 hours). Following catheterization, immediate palliative operation including a Blalock-Taussig shunt was carried out. Although all had a satisfactory PaO2 (mean, 49 mm Hg) postoperatively, the PGE1-nonresponsive patient experienced serious intraoperative bradycardia, hypotension, and acidosis in contrast to the PGE1-responsive group. In this study, the use of PGE1 was not associated with any apparent serious side effects.

Differential response of cultured mouse mammary cells of varying tumorigenicity to cytochalasin B.

Cultured BALB/c mouse mammary gland epithelial cells of varying oncogenic potential in vivo have been examined for their ability to multinucleate in the presence of cytochalasin B (CB). Highly tumorigenic cell lines derived from mammary tumors with hormonal, viral, or chemical carcinogen etiologies were extensively multinucleated when cultured in CB-supplemented medium. Normal mammary gland cells from either pregnant or lactating animals were predominantly mono- or binucleate under comparable conditions. At low passage levels after cloning, cell lines derived from a chemical carcinogen-induced mammary tumor were weakly oncogenic and remained largely mono-, or binucleated when cultured in CB-supplemented medium. At higher cell passage levels, both the ability to produce tumors in vivo and the degree of multinucleation in CB-supplemented medium increased dramatically with the clonal cell lines. Thus, the response of cultured mouse mammary gland epithelial cells to CB in vitro may be useful as a marker of the oncogenic potential of such cells.

Altered microfilament structure in cells transformed with a temperature-sensitive transformation mutant of murine sarcoma virus.

The structure and distribution of microfilaments were examined by electron microscopy in uninfected normal rat kidney (NRK) cells, murine sarcoma virus (MSV)-transformed NRK cells, and NRK cells infected with a cold-sensitive transformation mutant of MSV, i.e., NRK (MSV-1b) cells, grown at both permissive (39 degrees) and nonpermissive (33 degrees) temperature. The uninfected cells contained numerous microfilaments which were especially prominent at sites of intercellular adherens junctions. In contrast, the MSV-transformed cells contained few microfilaments and did not form adherens junctions. At 33 degrees, the NRK (MSV-1b) cells appeared normal but formed an altered form of adherens junction with disorganized microfilaments. At 39 degrees, these cells resembled NRK cells transformed by wild-type MSV but still formed a few of the altered type of adherens junctions. Disorganized adherens junction microfilaments were also found in cells newly infected with wild-type MSV. These results suggest that the perturbed assembly of microfilaments at adherens junctions may be an intermediate stage in the loss of adherens junctions during viral transformation.

Factors involved in concanavalin A agglutination of KB and NC37 cells grown in suspension culture.

NC37 and KB cells grown in suspension culture remained agglutinable at 23 degrees C by concanavalin A (Con A) after sufficient glutaraldehyde fixation to prevent lateral mobility (clustering) of Con A binding sites. In contrast, at 4 degrees C agglutination of the fixed cells was blocked. No significant differences in 3H-Con A binding were observed between unfixed cells and glutaraldehyde-fixed cells at 23 degrees C and unfixed cells at 4 degrees C. Con A bound to fixed cells at 4 degrees C produced agglutination when the cells were washed and then warmed to 23 degrees C. Thus a cold-sensitive factor unrelated to the binding of Con A or the clustering of Con A sites is necessary for agglutination to occur.

Ultrastructure of deoxyribonucleic acid-membrane associations in Escherichia coli.

Areas of contact between deoxyribonucleic acid (DNA) and intracytoplasmic membrane are frequently seen in the "extra" membrane-forming strain Escherichia coli 0111a(1). By examination of serial sections, it has been estimated that these DNA-membrane associations occur in at least 60% of the extra membrane-containing cells. Most of the DNA masses contained only one contact area. Several cells in which the DNA had been stretched revealed individual fibers connecting to the membrane, suggesting a firm attachment of DNA to membrane. The areas of membrane associated with DNA fibers were usually between 100 and 500 nm in diameter, although some smaller areas were seen. Electron microscopic autoradiography of cells in which the replication forks were labeled showed grains over 24% of the profiles containing a contact area, whereas there were grains over only 16% of the profiles without a contact area. Data from autoradiographs of cells in which the label was "chased" away from the replication fork showed the reverse labeling pattern. These data indicate that the areas of contact between DNA and intracytoplasmic membranes seen in electron micrographs contain the DNA replication forks.

Relation between deoxyribonucleic acid and intracytoplasmic membranes in Escherichia coli O111a.

The possibility of a relationship between intracytoplasmic membranes and deoxyribonucleic acid (DNA) in Escherichia coli O111a(1) has been investigated. To facilitate this investigation, a simple enzymatic assay for the amount of internal membrane present in a culture was developed. This assay was then used to show that the appearance of intracytoplasmic membranes is accompanied by an increase in the DNA content of the cells. Electron micrographs have confirmed this observation and have shown DNA to be in contact with the intracytoplasmic membranes. Extensive membranes were observed at sites of apparently unsuccessful attempts at cell division. These observations led to the conclusion that the internal membrane formed by strain O111a(1) represents "extra" membrane, which is functional in that it contains sites for DNA replication, but is produced in excess because the organism is somehow defective in its regulation of membrane synthesis.