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Biomedical subjects

M Frey

Publications and source records attributed to M Frey.

At least 235 records · Page 13Linked to original sources
PubMed1983

Consequences of uncontrolled calcium entry and its prevention with calcium antagonists.

Heart muscle fibres always undergo severe functional and structural alterations, finally resulting in necrotization, if free extracellular Ca2+ ions penetrate abundantly through the sarcolemma membrane into the myoplasm, so that the capacities of the Ca2+ binding or extrusion processes become overpowered. The crucial reaction consists of high-energy phosphate exhaustion which is brought about (a) by excessive activation of Ca2+-dependent intracellular ATPases, and (b) by Ca2+-induced impairment of the mitochondria. Intracellular Ca2+ overload proved to the common denominator in the pathogenesis of severe myocardial fibre injury and death produced under the following circumstances: Overdoses of beta-adrenergic catecholamines, dihydrotachysterol or vitamin D3, alimentary K+ or Mg2+ deficiency, hereditary cardiomyopathy of Syrian hamsters. Moreover, intracellular Ca2+ overload develops in the course of myocardial hypoxia or ischaemia thus causing additional precipitous damage of the mitochrondria. Following our first observations made in 1968, it has turned out that in all these cases, Ca2+ antagonists are capable of protecting myocardial cell integrity in that they prevent excessive transmembrane Ca2+ uptake. This is also true of the Ca2+ paradox: Ca2+ antagonists possibly inhibit the development of sarcolemmal leaks in the Ca2+-deprived myocardium. However, it is more likely that Ca2+ antagonists restrict the exaggerated influx of Ca2+ through these leaks, when the Ca+-deprived myocardial fibres return to a normal Ca2+-containing medium.

Adenosine Triphosphate↗
PubMed1983

The importance of the correct resting tension in muscle transplantation: experimental and clinical aspects.

The influence of a reduction of resting tension by elongation of the tendon on muscle function and morphology is investigated in the rectus femoris muscle of the rabbit. An elongation of the patellar tendon of 5 mm causes a reduction of the twitch tension to 73.5 percent of the contralateral control side and a reduction of the tetanic tension to 78.3 percent 6 months after surgery. The histologic, histochemical, and planimetric changes are similar to those reported by other authors for tenotomy, but they are less marked. The clinical relevance of these experimental results for free muscle transplantation with microneurovascular anastomoses and some technical details are discussed.

Animals↗
PubMed1983

Experimental free-muscle transplantation with microneurovascular anastomoses.

In 13 rabbits the rectus femoris muscle was freely transplanted from the left to the right side using microneurovascular anastomoses. About 7 months after surgery the muscle transplants were assessed functionally by force measurements. On the average, the transplanted muscles regained 55 percent of the maximal tetanic tension of unoperated, normal rectus femoris muscles, expressed as force per gram of muscle weight even 68 percent. After functional assessment, the muscles were weighed and then used for histologic, histochemical, planimetric, and biochemical evaluation. H&E-stained cross sections showed a high content of healthy muscle fibers; only some small atrophic and single fat cells were scattered over the cross sections. Good reinnervation over the sutured muscle nerve was confirmed by the type-grouping of muscle fibers in the NADH and myofibrillar ATPase staining. There was an excellent correlation between the functional results and the histologic picture as well as the content of choline acetyltransferase (CAT). A certain parallelism was found between the function of the transplants and the content of hexokinase, but none for the other estimated muscle enzymes, such as malate dehydrogenase (MDH), creatine kinase (CK), and lactic dehydrogenase (LDH). All enzyme levels were lower than in normal muscles. The results of this experimental series underline the utility of muscle transplantation with microneurovascular anastomoses to restore lost muscle function, even in the extremities, when strong forces are needed.

Animals↗
PubMed1983

Biochemical and physiological effects of compound 48/80 on canine trachea in vivo.

We studied changes in tracheal histamine content and tracheal muscle tension after degranulation of tracheal mast cells by compound 48/80 in 32 anesthetized dogs. In four dogs compound 48/80 caused an increase in tracheal tension [13 +/- 5 (SD) g/cm], while femoral arterial blood pressure decreased only 14 +/- 11%. Tracheal tissue histamine decreased 17 +/- 6% in five dogs receiving intra-arterial compound 48/80 (5 X 10(-3) to 10(-1) mg/kg). Chlorpheniramine, an H1-antagonist, selectively inhibited tracheal contraction to compound 48/80 and histamine. Cimetidine, an H2-antagonist, did not alter the response to intra-arterial histamine. In 11 dogs, the doses of both intra-arterial histamine and acetylcholine required to produce a threshold increase in tracheal tension of 8 g/cm were compared. Threshold doses for acetylcholine varied 10-fold, compared with 100-fold variation for histamine among these dogs. There was a significant correlation between increased tracheal tension produced by compound 48/80 and histamine (r = 0.62). We conclude that compound 48/80 causes a variable increase in tracheal tension in vivo because of marked variability in the H1-receptor response of tracheal smooth muscle to histamine and because of variability in the release of mediator from respiratory mast cells by compound 48/80.

Acetylcholine↗
PubMed1983

[Percutaneous measurement of oxygen partial pressure as an evaluation method of free flaps].

Transcutaneous, polarographic pO2-measurement can be used to estimate and monitor the circulation in free tissue transfers. Our experience in this field using a modified Clark's electrode is reported by presenting some examples. Its value in intraoperative and postoperative monitoring and for the early diagnosis of a critical reduction of blood flow in free flaps with microvascular anastomoses is assessed in the light of our early experience with this technique.

Blood Gas Analysis↗
PubMed1982

[Treatment of reflux esophagitis with ranitidine. A multicentric prospective study].

Thirty-eight patients with erosive-ulcerative reflux esophagitis were treated in an open trial with the histamine-H2-receptor antagonist ranitidine (150 mg twice daily). At endoscopy after 6 weeks there was evidence of complete healing of all epithelial defects in 20 of 38 patients (53%). Continuation of treatment for another 6 weeks in 13 patients was followed by healing in 6 additional patients as judged by endoscopy. Although the symptoms of the group as a whole improved significantly during treatment, there was no correlation between the degree of symptomatic improvement and healing of esophagitis. Also, the healing rate did not depend on age, sex, smoking and drinking habits or on the severity of esophagitis. It is concluded that medical treatment of reflux esophagitis with ranitidine is promising, even in severe cases previously considered candidates for surgery.

Anti-Ulcer Agents↗
PubMed1982

Crystal structure and electron transfer properties of cytochrome c3.

The crystal structure of cytochrome c3 from the sulfate-reducing bacteria Desulfovibrio desulfuricans, Norway strain, has been determined through the fitting of the recently completed primary structure to a 2.5 A resolution electron density map. The phase calculations were based on three mercurial derivatives; anomalous scattering data were used to refine the four heme iron positions. A preliminary refinement of the molecular model has led to a conventional crystallographic R factor of 34%. Cytochrome c3 is folded in two structural domains with one heme in each, the two other heme moieties lying in a large groove dividing the molecule. The core of the protein is the compact four-heme cluster which presents a relatively high degree of solvent exposure. The structural pattern of redox centers suggests that electron transfer might occur through direct contacts between some of the heme groups, via the overlapping system of pi oribitals or via intervening amino acid side chains or both.

Cytochrome c Group↗
PubMed1982

Isolation of DNA from single microsurgically excised bands of polytene chromosomes of Chironomus.

A method is described for excising by a glass knife single bands of isolated polytene chromosomes of the salivary glands of Chironomus tentans larvae. DNA strands were isolated from cut-out bands and their contour lengths were determined on electron micrographs. The mean contour length of DNA strands isolated from the double band I-8A was about twice that of the single band I-11B, namely 63 versus 34 micrometers. The described method may be applicable for molecular studies on single bands (e.g., by DNA cloning).

Animals↗
PubMed1982

An experimental comparison of the different kinds of muscle reinnervation: nerve suture, nerve implantation, and muscular neurotization.

In this experimental study, the changes in histologic pattern and functional recovery of the rectus femoris muscle of the rabbit were investigated 6 months after denervation and immediate microsurgical repair of the nerve supply of the muscle. Three different ways of reinnervation were used: nerve suture, nerve implantation directly into the muscle, and muscular neurotization by the underlying muscle. For evaluation, histochemical methods and tension measurements were used. In the results, nerve suture and nerve implantation were superior to muscular neurotization. Nevertheless, muscular neurotization was successful in all cases and led to positive EMG recordings. The functional recovery in the nerve suture and in the nerve implantation groups was astonishingly high and reached 70 to 80 percent of the tension of the control muscles. The results of this experimental study and their clinical relevance are discussed.

Animals↗
PubMed1982

Grip reconstruction by double-toe transplantation in cases of a fingerless hand and a handless arm.

In two cases, a grip reconstruction by double toe-to-hand transfer is demonstrated. In the first patient, all fingers of the left hand were amputated at the metacarpophalangeal joint level. The second and third fingers were reconstructed by transplantation of the second toe from the left foot and the third toe from the right foot. Although the distal and the middle phalanx of the transplanted third toe had to be amputated because of mummification 2 weeks after the transplantation and was covered with a groin flap, good function of the newly formed grip can be demonstrated. The second patient is a 21-year-old man with amputation of both hands at the wrist. A grip formation on the right lower arm was performed by transplantation of the second toe of each foot together with the metatarsal bone and a dorsalis pedis flap. Both metatarsal bones were fixed to the ulna and radius with metal plates, and tendons and nerves, together with a vascular supply, were reconstructed. One year after the operation, a follow-up study demonstrates good function of the newly formed "hand." The patient is able to use his two new "fingers" during daily life, mainly to hold small objects. A myoelectric prosthesis has been placed on the patient's left arm, and the patient uses this to hold bigger objects. Restoration of sensation and the range of movement of the newly formed right "hand" are demonstrated and discussed.

Adult↗
PubMed1982

Studies on the chalcone synthase gene of two higher plants: petroselinum hortense and matthiola incana.

Two higher plant systems are presented which allow to study coordinated gene expression of the light-induced metabolic pathway of flavonoid biosynthesis: tissue culture cells of Petroselinum hortense (Apiaceae) and different developmental stages of various genotypes of Matthiola incana (Brassicaceae). The gene structure of the chalcone synthase is mainly studied. A cDNA clone (pLF56) of parsley has been constructed and characterized conferring the chalcone synthase gene sequence. Strong cross hybridization between the parsley cDNA and Matthiola DNA allowed to identify a HindIII fragment (6000 bp) identical in size for parsley and different Matthiola wild type lines and a mutant line.

Acyltransferases↗
PubMed1981

[Plastic surgery after extensive tumor surgery of the scalp].

Extensive resections of tumors of the scalp penetrating into the bone and the brain often require the use of free flaps for coverage as the only possibility. Four cases are reported and the specific problems of these microsurgical operations in this region are discussed.

Adult↗
PubMed1981

[Surgical specialties in replantation surgery].

Special operative techniques developed by the advances in the replantation surgery are the subject of a review. The replantation of an amputated finger in a more important position is demonstrated by a clinical case. Defects can be replaced by parts of non-replanted fingers or with the aid of transplanted structures, such as skin, vessels, bone and local flaps. Clinical examples are given of the primary transplantation of bone from the iliac crest and of enhancement of circulation from the healthy, neighbouring finger.

Amputation, Traumatic↗