Biomedical subjects

A Breunig

Publications and source records attributed to A Breunig.

8 recordsLinked to original sources

PubMed1995

Bacillus oleronius sp.nov., a member of the hindgut flora of the termite Reticulitermes santonensis (Feytaud).

A new rod-shaped endospore-forming bacterium is described, which was isolated from the hindgut of the termite Reticulitermes santonensis (Feytaud). The isolate stains Gram negative and its DNA has a guanine-plus-cytosine content of 35 mol%. Despite the Gram-staining reaction, both biochemical and physiological features place the isolate in the genus Bacillus and indicate a phenotypic resemblance to the Bacillus firmus-lentus group of species. On the basis of comparative 16S rRNA analysis and some phenotypic features the isolate clearly represents a new species for which the name Bacillus oleronius is proposed. The type strain is Bacillus oleronius Rt 10 (DSM 9356).

Animals↗

PubMed1994

The phylogenetic position of Dimastigella trypaniformis within the parasitic kinetoplastids.

The nuclear 16S-like rRNA coding regions of two strains of the kinetoplastid flagellate Dimastigella trypaniformis Sandon (strain Ulm and strain Glasgow) were sequenced and phylogenetically analyzed. Strain Ulm was isolated from the hindgut contents of the Australian termite Mastotermes darwiniensis Frogatt, whereas strain Glasgow originates from a soil sample in Scotland. After preparation of genomic DNA the 16S-like rRNA coding regions were amplified using polymerase chain reaction (PCR) technology. The amplification products were cloned in a plasmid vector and sequenced according to standard methods. The sequence of the 16S-like rRNA coding region of strain Ulm differs less than 2% from the sequence of strain Glasgow, indicating that the two strains are most probably members of one species. Phylogenetic analysis of the sequence data positioned D. trypaniformis Sandon as a deep branching lineage near the root of the kinetoplastid group of flagellates.

Animals↗

PubMed1992

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex.

The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Cross-limb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity.

Adolescent↗

PubMed1992

[The treatment of open bite using magnets].

Until recently, surgical correction of the jaws has been widely regarded as the most effective treatment of open bites in the permanent dentition. In the following case report an open bite was treated non-surgical by intrusion of the molars with a magnet appliance. The forces of repelling magnets, fixed opposite in the upper and lower jaw were used to intrude the first and second molars. This intrusion allowed an autorotation of the mandible upward and forward to close the open bite. By reduction of the open bite of about 3 mm a surgical intervention could be avoided.

Adolescent↗

PubMed1991

Age differences in visual sensory integration.

Numerous authors have reported that elderly persons are more affected than young adults when submitted to reduced or conflicting sensory inputs conditions. These results, however, do not permit to evaluate whether the elderly suffer from a reduced peripheral sensibility or from a deficit in the central integrative mechanisms responsible for configuring the postural set. The present experiment evaluated the ability of elderly to reconfigure the postural set when submitted to successive reduced and augmented visual sensory conditions. Results showed that young and elderly subjects' sway dispersion increased when they were exposed to a reduced visual sensory condition (i.e., vision/no-vision transition). However, when exposed to augmented sensory condition (i.e., no-vision/vision transitions) young adult were able to adapt rapidly and reduced their sway dispersion whereas the elderly exhibited an increased sway dispersion. This inability to adapt to an augmented sensory condition suggest that elderly persons, in addition to a reduced peripheral sensibility, have a deficit with central integrative mechanisms responsible for reconfiguring the postural set.

Age Factors↗

PubMed1991

Postural sway characteristics of the elderly under normal and altered visual and support surface conditions.

One of the most pervasive findings in the literature on the aged is the general slowing of cognitive-motor responses with advancing age. Hence, an increased slowness in the processing of information from vestibular, visual, and somatosensory systems could contribute greatly to a decline in postural stability. To examine this question, in a cross-sectional investigation, postural sway behavior of elderly (n = 18) and young (n = 10) adults was examined under conditions that stressed the slower integrative mechanisms rather than the reflexive mechanisms of postural control. The postural sway behavior of young and elderly subjects was examined for a prolonged duration (80 s), under altered visual and/or support surface (5 cm thick foam surface) conditions, and contrasted with normal stance. Results showed that the exclusion or disruption of one of the sensory inputs, alone, was not consistently sufficient to differentiate between elderly and young adults, because of compensation by the remaining sensory sources. Both alterations together (i.e., visual and surface), however, had a substantially greater effect upon the elderly than the young.

Adult↗

PubMed1990

Influence of local sensory afference in the calibration of human balance responses.

Peripheral sensory modulation of balance behavior may require a "calibrated" mechanism which would maintain upright standing by a feedback control of torque at the ankle joint. The calibration of human balance was studied using a systematic presentation of perturbation excursions and velocities in normal freely standing subjects. All perturbations (posterior movements of a force platform) induced a forward body sway and were presented by first increasing and then decreasing the magnitude of perturbation. In preselected conditions the stability of the ankle and hence the accuracy of surface orientation inputs was altered using a foam base placed under the subjects feet. Each subject pressed a hand held response key at the moment a postural disturbance was detected. The automatic neuromuscular response (ANR) was recorded from the gastrocnemius muscles bilaterally and the perturbation detection time (DT) was obtained from the onset of thenar muscle discharge. The major findings in this study were: (1) Conscious DT changed as a function of step variations in perturbation excursion and was disassociated from the ANR latency. The ANR latency remained essentially constant in all conditions and did not have any influence on the kinematics of body sway. (2) Normalized peak body sway decreased during unstable ankle conditions and the reduction of body sway could be attributed to an increase in the gain of the ANR across a 200 ms integration period. The ANR 200 ms amplitude also showed higher correlations with perturbation magnitude during unstable (versus stable) ankle conditions. (3) The 200 ms gastrocnemius amplitude was modulated by excursion and velocity of platform displacement but the amplitude integrated over 100 ms was dependent on only the velocity of perturbation. Our results indicate that balance is controlled by a centrally initiated postural response but regulated in amplitude by local sensory information. These results establish that the gain of the ANR is functional, peripherally driven, and occurs subconsciously to alter the kinematics of body sway.

Adult↗

PubMedDate not supplied

Culture and phylogenetic characterization of Trichomitus trypanoides Duboscq & Grassè 1924, n. comb.: a trichomonad flagellate isolated from the hindgut of the termite Reticulitermes santonensis Feytaud.

A trichomonad flagellate strain R1 was isolated from the hindgut contents of the termite Reticulitermes santonensis Feytaud. The flagellate was cultivated at 28 degrees C in anaerobic medium containing yeast extract, minerals and vitamins. The isolate fed on living bacteria. It showed the typical morphological and ultrastructural features of the trichomonads, closely resembling Trichomitus trypanoides. In order to determine its phylogenetic position the small subunit ribosomal DNA (SSU rDNA) of the flagellate was amplified in vitro using the polymerase chain reaction (PCR), cloned in a plasmid vector and sequenced. Comparison of the obtained sequence with so far available SSU rRNA/rDNA sequences showed strongest similarity (89%) to the sequence of Tritrichomonas foetus. The phylogenetic analysis with parsimony and distance matrix methods placed Trichomitus trypanoides strain R1 near by the root of the phylogenetically so far analyzed eukaryotic organisms. This confirms that termites harbour hindgut symbionts, which originate from very early evolved eukaryotes.

Animals↗