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Biomedical subjects

H Ott

Publications and source records attributed to H Ott.

At least 19 recordsLinked to original sources
PubMed1998

Neurolin, the goldfish homolog of DM-GRASP, is involved in retinal axon pathfinding to the optic disk.

Young axons of new retinal ganglion cells (RGCs) in the continuously growing goldfish retina fasciculate with one another and their immediate forerunners on their path toward the optic disk and along the optic nerve. They express the immunoglobulin superfamily cell adhesion molecules (CAMs) neurolin (DM-GRASP) and the L1-like E587 antigen. Repeated injections of Fab fragments from polyclonal antisera against neurolin (neurolin Fabs) into the eye of 3. 4-cm-long and rapidly growing goldfish caused highly aberrant pathways of young RGC axon subfascicles in the dorsal retina. Many axons grew in circles and failed to reach the optic disk. In contrast, E587 Fabs, used in parallel experiments, disrupted the fascicles but did not interfere with the disk-directed growth. Neurolin Fabs also disturbed axonal fasciculation in vivo as well as in vitro but less severely than E587 Fabs. Coinjections of both Fabs increased defasciculation of the dorsal axons in both aberrant and disk-directed routes. They also disrupted the order of young RGC axons in the optic nerve more severely than E587 Fabs alone. This demonstrates that the development of tight and orderly fascicles in the dorsal retina and in the optic nerve requires both E587 antigen and neurolin. More importantly, our results suggest an involvement of neurolin in RGC axonal guidance from the retinal periphery to the optic disk. Because disrupted fascicles and errant axon routes were found only in the dorsal retinal half, a cooperation with so-called positional markers may be conceived.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed1997

Expression of an L1-related cell adhesion molecule on developing CNS fiber tracts in zebrafish and its functional contribution to axon fasciculation.

E587 antigen, an L1-related cell adhesion molecule, is expressed by growing axons and has previously been shown to enhance axon growth and to mediate fasciculation of axons from newborn retinal ganglion cells in goldfish. In zebrafish, the monoclonal antibody E17 against E587 antigen stains all axons in the primary tracts and commissures from 17 h postfertilization (pf) onward and axons which are added subsequently to this scaffold. Moreover, Fab fragments of an E587 antiserum (E587 Fabs) injected into the ventricle of 30-h pf zebrafish embryos caused a marked defasciculation of distinct axon bundles in the posterior commissure, in hindbrain commissures, and in longitudinal tracts of the hindbrain, where they also caused increased crossings between fascicles. The regulated expression of E587 antigen by all developing axons and the effects caused by E587 Fabs show that E587 antigen contributes to the formation of tight and orderly fascicles in the developing CNS.

Animals↗
PubMed1997

Clinical utility of contrast-enhanced MR angiography.

MR angiography (MRA) is a technique under ongoing discussion. Its non-invasiveness and sensitivity to flow irregularities make it an investigational technique which is easy to apply but which does not always lead to comprehensive results. It requires special skill to perform and also experience for correct interpretation of the results. The lengthiness of the procedure combined with certain physical properties tends to limit its use to mostly neurovascular applications. With the introduction of ultrafast MRA in conjunction with peripheral bolus-injection of extracellular contrast media, a new approach to the imaging of such regions as the thoracic and abdominal vasculature not to mention other vascular territories has become possible. In this paper, considerations of bolus and measurement optimization and timing protocols for dedicated indications are presented together with an overview on the experience acquired to date for CE-MRA of the carotid artery, mediastinal and pulmonary vessels, abdominal vasculature, and peripheral vessels. The main advantage of ultrafast CE-MRA is that patients are subjected to much more tolerable breath-hold investigations with the result that physiological motion such as peristalsis or major pulsation is minimised.

Adolescent↗
PubMed1996

[Myositis, polysynovitis and pulmonary fibrosis: anti-Jo-1 syndrome].

Polymyositis/dermatomyositis are rare autoimmune diseases. Classification is usually performed according to the criteria of Bohan and Peter. The occurrence of myositis-specific autoantibodies has recently been described in inflammatory myopathies. Approximately half of the patients can now be classified by these specific autoantibodies. Several of these autoantibodies (anti-aminoacyl-tRNA synthetases, anti-SRP, anti-Mi2) are strongly associated with the clinical presentation. We may expect that in the future different subsets of these diseases will be increasingly identified by serum antibodies. We report on a patient with myopathy, pulmonary fibrosis and polysynovitis, a typical clinical presentation of the anti-Jo1 syndrome (anti-synthetase syndrome).

Aged↗
PubMed1996

The effects of a benzodiazepine receptor antagonist beta-carboline ZK-93426 on scopolamine-induced impairment on attention, memory and psychomotor skills.

The effects of a single dose of scopolamine alone and in combination with ZK 93426 (a beta-carboline antagonist at the GABAA/BZ receptor complex with weak inverse agonist activity) were tested in two studies. In one study (study 1) the emphasis of enquiry was on different stages of information processing measured by a psychometric battery; in the second study (study 2) performance at different stages of memory and psychomotor abilities was tested and electroencephalogram recordings and video-tracking were also performed. Each study consisted of two parts, part I in which scopolamine (0.5 mg; 1 ml) or placebo were administered subcutaneously, and part II in which scopolamine (0.5 mg; 1 ml) was administered subcutaneously followed by an intravenous injection of ZK 93426 (0.04 mg; 0.04 ml/kg) or placebo. Thirty-six volunteers, who were randomly allocated to receive one of the two treatments (n = 18 per treatment), participated in each part. In study 1 attention was measured by a continuous attention task and a rapid information processing task, vigilance was measured by a visual vigilance task, and working memory and reasoning were evaluated by a logical reasoning task. A visual memory task was also included to measure acquisition and retention. In study 2 acquisition and short term storage and retrieval were measured by a word lists-Buschke restricted reminding procedure, and retention was tested by delayed recall and recognition. Psychomotor performance was assessed by measuring tapping speed (related to gross motoric abilities) and a pegboard task (related to fine motoric abilities). A task to measure working memory, the Pauli test, was also included. In study 1 scopolamine significantly impaired performance in the attentional and vigilance tasks (P < 0.05), but there was no effect in the logical reasoning task main measurements of time and accuracy. In study 2, scopolamine also impaired performance in the psychomotor tasks (P < 0.05) and the Pauli test. ZK 93426 partially antagonised most of the effects of scopolamine on memory and attention, suggesting that an interaction between the GABA-ergic and cholinergic systems is reflected in measurements of both attention and memory. In general a dissociation was found in the effects of scopolamine on memory, i.e. scopolamine impaired performance during all acquisition measurements but left retention unaffected.

Adult↗
PubMed1996

Citrate in synovial fluid and its relation to inflammation and crystal presence.

OBJECTIVE: To investigate the role of citrate in the pathophysiology of arthritides with calcium pyrophosphate dihydrate (CPPD) crystals and/or apatite-like material. METHODS: We measured citrate concentrations in the plasma and synovial fluid (SF) of 23 joints whose SF contained these crystals and 33 joints without crystals. The SF originated from 25 joints each of patients with rheumatoid arthritis (RA) and primary osteoarthritis (OA) and 10 patients with various other inflammatory joint diseases. RESULTS: There was significant correlation between citrate concentrations in the SF and plasma with values globally twice as high in the SF as in the plasma. Citrate concentrations in the SF of patients whose SF contained CPPD crystals and/or apatite-like material were not significantly lower than those without crystals. On the other hand, citrate concentrations were significantly lower in the SF of patients with RA and other inflammatory joint diseases versus those with OA. CONCLUSION: We have no evidence that lower amounts of citrate in SF favor the presence of CPPD crystals or apatite-like material. Our results, however, do suggest a complex regulation of the citrate concentration in SF where cellular metabolic processes and citrates arising from the plasma and neighboring tissues probably interact to produce the levels recorded.

Adult↗
PubMed1995

Fish E587 glycoprotein, a member of the L1 family of cell adhesion molecules, participates in axonal fasciculation and the age-related order of ganglion cell axons in the goldfish retina.

Axons derived from young ganglion cells in the periphery of the retinae of larval and adult goldfish are known to fasciculate with one another and their immediate forerunners, creating the typical age-related order in the retinotectal pathway. Young axons express the E587 antigen, a member of the L1 family of cell adhesion molecules. Repeated injections of Fab fragments from a polyclonal E587 antiserum (E587 Fabs) into the eye of 3.4 cm goldfish disrupted the orderly fascicle pattern of RGC axons in the retina which was preserved in controls. Instead of bundling tightly, RGC axons crossed one another, grew between fascicles and arrived at the optic disk in a broadened front. When added to RGC axons growing in vitro, E587 Fabs neutralized the preference of growth cones to elongate on lanes of E587 protein, caused defasciculation of axons which normally prefer to grow along each other when explanted on polylysine, and prevented clustering of E587 antigen at axon-axon contact sites. Monoclonal E587 antibody disturbed axonal fasciculation moderately but led to a 30% reduction in growth velocities when axons tracked other axons. Therefore we conclude that E587 antigen mediates axonal recognition, selective fasciculation and the creation of the age-related order in the fish retina.

Aging↗
PubMed1994

[Isolated bone marrow mastocytosis: a rare cause of osteoporosis not to be missed].

Osteoporosis can be secondary to other diseases. Among these, mastocytosis is easily recognized when typical skin lesions and systemic symptoms are present. When mastocytosis is confined to bone, as in our case, diagnosis is based on the presence in the bone marrow of an increased number of mastocytes with a nodular arrangement near the bone trabeculae. The diagnosis has to be suspected when severe vertebral and peripheral osteoporosis occurs in middle aged people, especially men. Bisphosphonates are the most frequently applied treatment but their efficacy is limited. Early diagnosis is recommended because the use of several drugs, including fluoride, which is frequently used in osteoporosis.

Aged↗