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Biomedical subjects

H Sommerschild

Publications and source records attributed to H Sommerschild.

At least 19 recordsLinked to original sources
PubMed2004

Adenosine A receptors are necessary for protection of the murine heart by remote, delayed adaptation to ischaemia.

AIMS: Adenosine is involved in classic pre-conditioning (PC) in most species, acting through especially adenosine A1 and A3 receptors. We studied whether the adenosine A1 receptor (A1R) was important for remote, delayed adaptation to ischaemia using a mouse with targeted deletion of the A1R gene. METHODS: Remote, delayed adaptation was evoked by brain ischaemia (BIPC) through bilateral ligation of the internal carotid arteries. Through microdialysis probes placed in the brain and the abdominal aorta, we found that plasma adenosine increased following carotid artery ligation. Twenty-four hours after ligation, hearts were isolated, Langendorff perfused and subjected to 40 min global ischaemia and 60 min reperfusion. Hearts from sham operated and BIPC animals either with (A1R+/+) or without (A1R-/-) the gene for the adenosine A(1)R were compared with each other. RESULTS: In wild types, BIPC reduced infarct size and improved functional recovery during reperfusion, but BIPC did not protect hearts of A1R-/- mice. There were no significant differences between sham-operated A1R+/+ and A1R-/- in recovery of function or infarct size. The mitogen-activated protein kinases (MAPKs) extracellular signal-regulated protein kinase1/2 (ERK1/2), p38 and c-jun N-terminal kinase (JNK) were phosphorylated during reperfusion of sham treated hearts. The increase in ERK1/2 and p38 phosphorylation detected was attenuated in hearts of BIPC or A1R-/- animals. CONCLUSION: During BIPC adenosine acting on the A1R appears necessary for myocardial protection. MAPK signalling may possibly be involved in organ protection during the delayed phase of remote, delayed adaptation.

Adaptation, Physiological↗
PubMed1997

Repetitive stretching during low-flow ischemia impairs function in isolated porcine hearts: a model for segmental dyskinesis.

Myocardial infarction appears after 20 min of regional no-flow ischemia in vivo, but only after a much longer duration of global ischemia in isolated hearts. We tested whether repetitive myocardial stretching (RMS), as occurs in segmental ischemia, is involved in the pathogenesis of myocardial cell injury. Furthermore, we evaluated the role of stretch-activated channels by using Gadolinium (Gd3+). Isolated piglet hearts were perfused with red cell enriched Krebs-Henseleit buffer. RMS was induced by inflating a balloon in the left ventricle, using a control system to provide a pressure of 120 mmHg during one-third of the cycle and 0 mmHg during the rest of the cycle, with a frequency 150 per min. Function and metabolism were compared during 2 h of low-flow ischemia (10% of control), with and without RMS, followed by 1 h of reperfusion. Non-RMS hearts were exposed to saline (Isch), or Gd3+ 25 micromol/l (Gd3+-Isch). During ischemia, left ventricular systolic pressure (LVSP) stabilized in non-RMS hearts, but a further decrease, combined with increased anaerobic metabolism occurred in RMS hearts. After 30 min of reperfusion in the non-stretched hearts, LVSP returned to 77+/-4% of control (mean+/-s.e.) in the Isch group, and to 74+/-2% in the Gd3+-isch group (between groups; P=n.s.). In hearts exposed to RMS, LVSP returned to only 46+/-4% of control (RMS) and to 51+/-3% in the Gd3+-RMS group (both P=0.01 v Isch). The same alterations were seen for LV dP/dt. In RMS hearts, tissue concentrations of ATP were reduced and concentrations of lactate increased. We conclude that stretching of ischemic myocardium severely increases anaerobic metabolism and reduces functional and metabolic recovery. Blockade of stretch activated channels by Gd3+ does not prevent this effect. Thus, the reduced recovery induced by RMS is due to factors other than ion fluxes through stretch-activated channels.

Animals↗
PubMed1991

Eccrine angiomatous hamartoma of the finger leading to amputation.

A case of eccrine angiomatous naevus in a 34-year-old pregnant woman is described. The tumour was located on the dorsal aspect of the distal phalanx of the left little finger causing severe pain. Partial resection provided no improvement and finally amputation was necessary. Histological examination revealed the typical appearance of an eccrine angiomatous hamartoma with a large number of eccrine ducts combined with vascular structures.

Adult↗
PubMed1988

Control of number and distribution of synapses during ectopic synapse formation in adult rat soleus muscles.

Changes in the number and distribution of synaptic inputs and acetylcholine receptor clusters were studied during the formation of ectopic nerve-muscle junctions between the transplanted fibular nerve and the denervated soleus muscle of adult rats. The tibial nerve was cut 3 weeks after implanting the fibular nerve. New sites of transmission were first detected 3 days after the cut. These sites were located electrophysiologically, marked by dye and found to coincide with clusters of acetylcholine receptors. There were no ectopic clusters away from fibular nerve sprouts and no clusters on muscles which had not been denervated. Three days after cutting the tibial nerve, the acetylcholine receptor clusters, and probably also the sites of transmission, were randomly distributed along individual muscle fibres. Six days after the cut, the clusters continued to be randomly distributed whereas the synaptic inputs were either close together (within 300 microns) or more than 600 microns apart. Two weeks later the spatial distributions of both clusters and inputs were similar with peaks around 100-300 microns, 1200-1400 microns and 2000-2600 microns. No ectopic clusters were closer than 0.5 mm to the original endplate. We conclude that nerve-muscle contacts and associated acetylcholine receptor clusters initially form at random. One or a few of these contacts develop further and, as a result, the surrounding regions undergo changes that prevent the contacts initially formed there from being maintained. Apparently, in this preparation, approximately 1.5 mm length of fibre is needed to support the maturation and maintenance of each ectopic endplate (mean length 111 micron).

Animals↗
PubMed1987

Prevention in child psychiatry.

Prevention in child psychiatry may be divided into two different areas: Promotion of mental health and prevention of psychiatric illness. In promotion of mental health the target is the total population and one has to deal with values within the sociocultural frame of reference. Research pilot projects have been carried out by the establishment of different parents groups. The intention of this group-work has been of a cultural--not an educational--nature. We have tried to create a replica of the lost possibility of cultural transference of skills and norms in caring and upbringing. In prevention of psychiatric illness the work must be based on epidemiology and the risk groups are the specific target. Research projects in prevention have been rather limited, but we may draw two conclusions: To identify the risk children has not been the problem--the interventions must be rather comprehensive for counteracting the risk factors, rendering them harmless.

Child↗
PubMed1987

Central venous catheter with subcutaneous injection port (Port-A-Cath): clinical experience with children.

Long-term intermittent venous access was established in 26 children by means of a central venous catheter (CVC) with a subcutaneous injection port (Port-A-Cath) (PAC). As of December, 1985, PACs had been in place for 20-750 days (cumulative 10,890 days) with 647 entries into the system. The PACs were used for blood sampling and administration of chemotherapy, antibiotics, fluids, total parenteral nutrition (TPN), and blood products. One patient with sever neutropenia (absolute neutrophil granulocyte count [ANC] less than 0.1 x 10(9)/L) at the time of the PAC implant developed an infection around the port after 2 days, with subsequent septicemia (Bacillus cereus) necessitating removal of the PAC. Otherwise, no definite PAC-related infections occurred, including 258 days of neutropenia (ANC less than 0.5 x 10(9)/L). Two PACs were found occluded with greyish deposits of fat and organic material after long-term (45 and 61 days) continuous TPN and were removed. Malposition of catheter, extravasation, thrombosis, and other potential technical or psychological complications were not observed. The children continued normal activities, and the easy venous access decreased emotional stress during treatment. Local doctors were trained to use the PACs, with which they administered maintenance chemotherapy. We conclude that the use of PACs in children is safe, even in the first year of life, and has many advantages when compared with other CVCs currently in use. Strict indications, meticulous implantation technique, and adequate handling are, however, mandatory.

Adolescent↗
PubMed1986

Duodenal duplication--a case with special features.

A duodenal duplication almost as large as the stomach proper was found along the greater curvature of the stomach in a 6-month-old Caucasian girl. There was a wide communication with the proximal part of the duodenum, from which the duplication blood supply originated. The duplication and the stomach shared the serosal lining, but had individual, full thickness walls. The duplication was removed in toto, and the communication with the duodenum was closed by transverse suture. The luminal lining of the duplication consisted of corpus type of gastric mucosa. There was a 1 X 1 cm mucosal ulceration in the region of which respiratory tract elements were found. The condition is interpreted as a duodenal duplication with ectopic gastric mucosa and respiratory tract elements. To our knowledge, the occurrence of respiratory tract elements in an intestinal duplication BELOW the diaphragm is being reported for the first time. It offers a challenging explanation for the ulceration found within this duplication.

Barium Sulfate↗
PubMed1981

Formation of ectopic neuromuscular junctions in adult rats.

The formation of ectopic neuromuscular junctions between a transplanted foreign nerve (the superficial fibular nerve) and the denervated soleus muscle was examined in adult rats. Formation of new junctions was induced by denervating the soleus muscle by cutting the tibial nerve. Junctional transmission began 3 days after denervation when denervation was done 3 weeks after transplantation of the foreign nerve, and progressively later when denervation was done 8, 16 and 24 weeks after transplantation. The rate at which the transmission, once started, acquired mature characteristics was approximately the same in each case. Initially, spontaneous m.e.p.p.s were infrequent, long lasting with a skewed amplitude distribution. The e.p.p.s evoked by stimulation of the foreign nerve were then commonly below threshold for eliciting action potentials and were occasionally no larger than the size of the spontaneous m.e.p.p.s. M.e.p.p. characteristics became normal in the 2nd week after transmission had started. Fully effective evoked transmission with every innervated fibre responding with overshooting action potential occurred 1-3 months after onset of transmission.

Action Potentials↗
PubMed1976

Ultrastructure of the new neuromuscular junctions formed during reinnervation of rat soleus muscle by a "foreign" nerve.

In rats the "fast" fibular nerve was transposed to the "slow" soleus muscle outside the original innervation band. Formation of new neuromuscular junctions was induced by cutting the soleus nerve after different periods of time. The morphological maturation of these junctions was studied by electron microscopy. New neuromuscular junctions do not form when the original innervation is left intact. Three to five days after denervation, vesicle-laden terminal boutons contact muscle fibers with only the basal lamina of the latter intervening. Three weeks after denervation, most boutons are larger and postsynaptic folds are present, although younger stages are also seen. Sixteen weeks after denervation, the neuromuscular junctions appear mature. This corresponds well with electrophysiological findings in the same material. The fully developed neuromuscular junctions sixteen weeks after denervation possess postsynaptic folds similar to those of normal "fast" muscle fibers. This suggests that the "fast" fibular nerve rather than the "slow" soleus muscle fibers determines the morphology of the postsynaptic folds. Possible trophic neuromuscular interactions are discussed.

Animals↗
PubMed1976

Persistence of junctional acetylcholine receptors following denervation.

The relative number of acetylcholine receptors at normal and denervated end plates in rat soleus muscles was studied using the binding of 125I-alpha-bungarotoxin as a quantitative assay. After short-term denervation (up to 2.4 weeks), the extrajunctional binding increased, but there was no change in specific binding to the motor end plate. Denervation for longer periods (up to 7 weeks) reduced binding sites at the end plate by as much as 60-70%. Direct electrical stimulation of these muscles for the entire period of denervation did not prevent the slow loss of junctional binding sites, even though it was adequate to abolish the increase in extrajunctional binding. Cross-innervation by a foreign nerve at a site distant from the original end plates was more effective than stimulation in preserving the old end plates; in cross-innervated muscles, many denervated end plates continued to bind normal amounts of toxin for over 4 months. In comparison with the rapid rate of appearance or disappearance of extrajunctional ACh receptors, however, the number of junctional receptors at all denervated end plates was quite stable, suggesting that the persistence of these receptors is not immediately dependent on the presence of a motor nerve terminal.

Acetylcholine↗
PubMed1975

Cholinergic receptors at denervated mammalian motor end-plates.

The number of acetylcholine receptors at normal and denervated end-plated in rat soleus muscles was studied using the binding of [125A] alpha-bungarotoxin as a quantitative assay. Normal end-plates bound several thousand times as much toxin as equal areas of extra-synaptic muscle membrane. After short-term denervation (up to 2.4 weeks) the extrajunctional binding increased, but there was no change in specific binding to the motor end-plate. Denervation for longer periods (up to 7 weeks) reduced binding sites at the end-plate by up to 60-70%. Direct electrical stimulation of these muscles for the entire period of denervation did not prevent the loss of junctional binding sites even though it was adequate to abolish the increase in extrajunctional toxin binding. In contrast, denervated end-plates on muscle fibres cross-innervated by a foreign nerve at a distant location continued to bind normal amounts of toxin for over four months.

Animals↗