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Biomedical subjects

M Adrian

Publications and source records attributed to M Adrian.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effects of foot orthoses on center-of-pressure patterns in women.

The purpose of this study was to determine the effects of foot orthoses on the pattern of center of pressure in women with forefoot deformities during walking. Nine subjects with a forefoot varus and nine subjects with a forefoot valgus walked across a force platform three times for each of the following five treatment conditions: 1) barefoot, 2) shoes only, 3) rigid orthoses with shoes, 4) semi-rigid orthoses with shoes, and 5) soft orthoses with shoes. Force data were analyzed to determine the area under the center-of-pressure curve. A significant omnibus F ratio was obtained for treatments (p less than .001) and the deformity X treatments interaction (p less than .05) using a two-factor, mixed analysis of variance for repeated measures. Tukey's post hoc comparisons for the Varus Group resulted in significant differences (p less than .05) between the following treatment conditions: 1) barefoot and shoes only, 2) barefoot and rigid orthoses with shoes, 3) barefoot and semi-rigid orthoses with shoes, and 4) barefoot and soft orthoses with shoes. Tukey's post hoc comparisons for the Valgus Group resulted in significant differences (p less than .05) between the following treatment conditions: 1) barefoot and rigid orthoses with shoes, 2) barefoot and semi-rigid orthoses with shoes, and 3) barefoot and soft orthoses with shoes. The shoes-only treatment condition, in comparison with the barefoot condition, significantly reduced the center-of-pressure area for the Varus Group only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Effect of heel lifts on ground reaction force patterns in subjects with structural leg-length discrepancies.

The purpose of this study was to determine the effect of heel lifts on ground reaction force patterns in subjects with structural leg-length discrepancies (LLDs). Eighteen subjects with LLDs ranging from 4.8 to 22.2 mm participated in this study. Subject age range was from 20 to 63 years. A force platform was used to obtain ground reaction force data for four conditions. Data were collected prior to fitting of the heel lift and after a three-week break-in period. Data were analyzed by use of a two-factor within-subject analysis of variance for repeated measures. Before heel-lift fitting, maximum lateral force was greater in the short leg than in the long leg. After heel-lift fitting, maximum vertical force was greater within both legs, and maximum medical force was greater in the long leg than in the short leg. The results suggest that although heel lifts are used to achieve pelvic levelness, the use of heel lifts also resulted in increased ground reaction forces, which may cause increased joint stresses within the lower extremities.

Adult↗
PubMed1988

Length and shape variants of the bacteriophage T4 head: mutations in the scaffolding core genes 68 and 22.

The shape and size of the bacteriophage T4 head are dependent on genes that determine the scaffolding core and the shell of the prohead. Mutants of the shell proteins affect mainly the head length. Two recently identified genes (genes 67 and 68) and one already known gene (gene 22), whose products are scaffold constituents, have been investigated. Different types of mutants were shown to strongly influence the proportion of aberrantly shaped particles. By model building, these shape variants could be represented as polyhedral bodies derived from icosahedra, through outgrowths along different polyhedral axes. The normal, prolate particle is obtained by elongation along a fivefold axis. The mutations of the three core genes (genes 67, 68, and 22) affect the width mainly by lateral outgrowths of the prolate particle, although small and large isometric particles are also found. Many of the aberrant particles are multitailed, suggesting a correlation between tail attachment sites and shape.

DNA Mutational Analysis↗
PubMed1986

Cryo-electron microscopy of vitrified SV40 minichromosomes: the liquid drop model.

The structure of SV40 minichromosomes has been studied by cryo-electron microscopy of vitrified thin layers of solution. In high-salt buffer (130 mM NaCl), freshly prepared minichromosomes are condensed into globules 30 nm or more in diameter. On the micrograph, they appear to be formed by the close packing of 10 nm granules which give rise to a 10 nm reflection in the optical diffractogram. The globules can adopt many different conformations. At high concentration, they fuse into a homogeneous 'sea' of closely packed 10 nm granules. In low-salt buffer (less than 10 mM NaCl), the globules open, first into 10 nm filaments, and then into nucleosome-strings. The 'liquid drop' model is proposed to explain the condensed structure of the minichromosome in high-salt buffer: nucleosomes stack specifically on top of one another, thus forming the 10 nm filaments. 10 nm filaments in turn, tend to aggregate laterally. Optimizing both these interactions results in the condensation of 10 nm filaments or portions thereof into a structure similar to that of a liquid. Some implications of this model for the structure of cellular chromatin are discussed.

Animals↗
PubMed1985

pH-dependent membrane fusion is promoted by various colicins.

The ability of colicin A, a bacteriocin produced by some Enterobacteriaceae, to fuse phospholipid vesicles at acidic pH, was demonstrated by electron microscopy and resonance energy transfer. The fusion depends on protein concentration and on the nature of the phospholipids. Vesicles, prepared from Escherichia coli phospholipids, fused one or more rounds at pH 4.5 upon addition of stoichiometric amounts of colicin A. Fusion was not only induced by pore-forming colicins (E1, K) but also by colicins that contain nuclease activities (E2, E3). By recombinant DNA technology it is shown that the first glycine-rich 70 NH2-terminal amino acids and, most probably, the extreme COOH-terminal end of colicin A are involved in the fusion activity of the protein. The physiological relevance of this property of colicins is discussed.

Colicins↗
PubMed1984

Cryo-electron microscopy of vitrified insect flight muscle.

Frozen hydrated sections of vitrified unstained insect flight muscle in the rigor and relaxed states were studied by cryo-electron microscopy. High resolution images with good contrast were obtained. As judged from direct images and from the comparison of optical diffractograms with X-ray diffraction patterns obtained from glycerinated muscle fibres, the vitrified specimen is well preserved. Preparation artifacts encountered in conventional plastic sections are avoided. The preservation of the relaxed structure also seems better than in freeze-etched replicas as the 14.5 nm repeat of crossbridges on thick filaments is easily visible.

Animals↗
PubMed1980

Effect of phenformin on the metabolism of glucose, pyruvate and acetate in guinea-pig heart.

In the isolated perfused heart of the guinea-pig, phenformin could be shown to have a characteristic effect on cardiac performance and metabolism. In the working heart, phenformin (1 mmol1/1) decreased dp/dt and increased the end diatolic pressure; this reduced heart performance could not be explained by changes in the content of energy-rich compounds. Furthermore, phenformin increased lactate production in hearts perfused with glucose as substrate and inhibited the utilisation of pyruvate, but not of acetate. The activity of the purified pyruvate dehydrogenase complex was not influenced by phenformin, but the active form of the pyruvate dehydrogenase complex (PDHa) was diminished. This effect may be explained by an inhibition of the pyruvate dehydrogenase phosphatase. An inhibition of pyruvate dehydrogenase and, coincidently, of oxygen consumption might contribute to the development of lactic acidoses and, particularly, might be deleterious for the heart.

Adenine Nucleotides↗
PubMed1978

[Spirochetes: coiling direction].

On electron micrographs of spirochetes, the axial fibers are alternatively visible and hidden, i.e. above then under the cytoplasmic cylinder. From this observation the sense of coiling can be inferred. Leptospires are right-handed structures. So are other spirochetes, but it is less conspicuous. The opposite, however, appears on most published photographs and on schematic drawings. The explanation would be that the preparation introduced into the electron microscope was not facing the photographic plate, but turned to the electron beam. Also the picture must not be turned over, neither in the photographic laboratory nor when used as a slide.

Leptospira↗
PubMed1978

[Absorption and oxidation rate of arginine and malate (author's transl)].

Six normal volunteers received L-Arginin and DL-Malat p.o. in order to test absorption and utilisation of these compounds. Both compounds are almost completely reabsorbed from the intestine and then metabolized. Only about 2% of the arginine applied are recovered in the urine. 15% of arginine and 45% of malate applied are metabolized within 8 hours. If absorption is unimpaired oral therapy of hyperammoniemia would require application of the malate-arginine solution for every 3 hours, if constant plasma levels are to be achieved.

Adolescent↗
PubMed1977

[Audiometry and cytological study of the external hair cells of 4 strains of mice].

The auditory apparatus of two strains of mices with normal audition is compared to that of two substrains with genetic auditory impairment. Audiometry by auditory evoked potentials at the inferior collicular level indicates complete deafness for one substrain and a 40-48 dB S.P.L. hearing loss at all frequencies for the other. Scanning and transmission electron microscopy demonstrate hair impairment of the external hair cells and degeneration of the chondriosome for the two deaf substrains.

Animals↗
PubMed1977

Electrogoniometric analysis of equine metacarpophalangeal joint lameness.

Electrogoniometry was used qualitively and quantitatively to assess the movements of the normal and pathologic metacarpophalangeal joints of selected horses. A total of 4 Thoroughbreds, 1 normal and 3 with clinical and radiographic changes in the metacarpophalangeal joints of 1 limb, were evaluated at the walk and trot. Goniograms of the affected joints were compared with those of the normal horse and the normal contralateral metacarpophangeal joint. Qualitative asymmetry was recognized on the goniograms, and the ranges of motion were quantified and related to the clinical and radiologic observations.

Animals↗