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Biomedical subjects

C Timm

Publications and source records attributed to C Timm.

At least 19 recordsLinked to original sources
PubMed2003

Frontal lobe dysfunctions in Korsakoff's syndrome and chronic alcoholism: continuity or discontinuity?

The effect of long-term heavy alcohol consumption on brain functions is still under debate. The authors investigated a sample of 17 Korsakoff amnesics, 23 alcoholics without Korsakoff's syndrome, and 21 controls with peripheral nerve diseases, matched for intelligence and education. Executive functions were examined for word fluency, the modified Wisconsin Card Sorting Test, an alternate response task, and an "n-back" working memory task. Korsakoff amnesics, but not alcoholics, showed a marked memory impairment. They also scored lower in each of the executive tasks-the alcoholics only in the alternate response task. This task also correlated with the years of the alcohol dependency. First, the authors conclude that Korsakoff's syndrome is associated not only with a memory impairment but also with a global executive deficit. Second, the decline in the ability to alternate between different responses argues for a restricted neurotoxic effect of alcohol on some frontal lobe areas.

Adult↗
PubMed2002

Correlated defects, metal-insulator transition, and magnetic order in ferromagnetic semiconductors.

The effect of disorder on transport and magnetization in ferromagnetic III-V semiconductors, in particular (Ga,Mn)As, is studied theoretically. We show that Coulomb-induced correlations of the defect positions are crucial for the transport and magnetic properties of these highly compensated materials. We employ Monte Carlo simulations to obtain the correlated defect distributions. Exact diagonalization gives reasonable results for the spectrum of valence-band holes and the metal-insulator transition only for correlated disorder. Finally, we show that the mean-field magnetization also depends crucially on defect correlations.

Journal Article↗
PubMed2000

Doping dependence of the Neel temperature in mott-hubbard antiferromagnets: effect of vortices

The rapid destruction of long-range antiferromagnetic order upon doping of Mott-Hubbard antiferromagnetic insulators is studied within a generalized Berezinskii-Kosterlitz-Thouless renormalization group theory in accordance with recent calculations suggesting that holes dress with vortices. We calculate the doping-dependent Neel temperature in good agreement with experiments for high- T(c) cuprates. Interestingly, the critical doping where long-range order vanishes at zero temperature is predicted to be x(c) approximately 0. 02, independently of any energy scales of the system.

Journal Article↗
PubMed1987

Rhabdomyosarcomatous component in dedifferentiated chondrosarcoma.

The case of a 57-year-old male is described with an extended bone tumor in the proximal left femur. The tumor is histologically classified as dedifferentiated chondrosarcoma. Immunohistologic examination revealed a strong positive reaction for desmin mainly in the tumor giant cells in the dedifferentiated areas, whereas chondroblasts in the low grade chondrosarcoma areas reacted negatively with desmin. In accordance with some cross striation in polymorphic tumor cells this points to a rhabdomyosarcomatous component in the dedifferentiated portions of the tumors. Thus, in addition to fibrosarcomatous, osteosarcomatous and malignant fibrous histiocytoma-like areas, our case presents another sarcomatous constituent in dedifferentiated chondrosarcoma.

Bone Neoplasms↗
PubMed1986

[Radiological diagnosis of aggressive fibromatosis].

Aggressive fibromatosis (desmoid, desmoid tumour) resembles, in its infiltrating and destructive growth, a fibrosarcoma, but does not metastasize. Because of its high recurrence rate, the tumour remains a surgical problem. Various imaging methods were evaluated retrospectively in 23 patients with histologically confirmed aggressive fibromatosis. Conventional radiological procedures are poor at demonstrating the extent and type of tumour. Modern tomographic methods are more able to determine the size of the lesion and a combination of angiography and CT can frequently provide a definite diagnosis.

Adolescent↗
PubMed1986

Human atrial natriuretic peptide (hANP) has no effect upon dopaminergic pathways: preliminary evidence in nude mice bearing heterotransplanted human CONN's adenoma tissue.

To examine whether human atrial natriuretic peptide (hANP) has an agonistic effect on dopaminergic pathways, we studied the natriuretic action and the suppressive effect of hANP on aldosterone secretion before and during treatment with haloperidol or pergolide in nude mice harbouring heterotransplanted human CONN's adenoma tissue. Nude mice with heterotransplanted tumour material without hormonal activity served as controls. The natriuretic efficacy of hANP remained unchanged by haloperidol or pergolide both in controls and in nude mice with heterotransplanted CONN's adenoma tissue. On the other hand, hANP had no effect upon the haloperidol-induced increase in aldosterone excretion in the control animals. Thus, preliminary evidence emerges that hANP has no effect on dopaminergic pathways and that the aldosterone inhibiting action of hANP is only of minor physiological significance.

Adenoma↗
PubMed1986

[Femur head necrosis in sickle cell anemia].

The clinical course and therapy of femoral head necrosis after a minimal trauma in a 14 year old Turkish girl with sickle cell anemia is described. In this hemoglobinopathy one must be aware of complicated clinical courses even after minor accidents. The immediate start of therapy in an acute crisis and the early diagnosis of bone infarction and femoral head necrosis are necessary to avoid large bone defects.

Adolescent↗
PubMed1986

[Regional myocardial ischemia in the conscious dog under echocardiography control].

Regional myocardial dysfunction is a very sensitive and early parameter of myocardial ischemia. One minute occlusion of the left anterior descending (LAD (n = 8) and circumflex coronary artery (CCA) (n = 8) by means of hydraulic occluders was performed in 10 chronically instrumented conscious dogs. In a left ventricular cross-section diastolic and systolic area (DA, SA) and area shortening (AS) as well as regional function of 6 radial sectors were evaluated with 2D echocardiography. After occlusion of the LAD, SA increased by 33% (p less than 0.05), AS decreased by 22% (p less than 0.05) while the DA remained unchanged. In 2 of 6 radial sectors (anteroseptal) shortening decreased by 41% (p less than 0.01) and 54% (p less than 0.001) respectively. Occlusion of the circumflex coronary artery CCA caused an increase in DA (18%) and SA (33%) and a reduction of AS by 24% (p less than 0.01). Contraction of the anterior wall (sectors 2 and 3) was reduced by 61% and 57% (p less than 0.001). In the same animal 10 one minute occlusions of the LAD with 5 min intervals of reperfusion caused a reproducible depression of sector 6 (septal) from 63.2 +/- 5.4% to 16.3 +/- 3.4%. In another animal 11 one minute CCA occlusions with 5 min intervals of reperfusion reproducibly decreased the contraction of sector 3 (anterior) from 85.2 +/- 6.7% to 21.4 +/- 17.0%. 2D-E allows a reproducible estimation of regional left ventricular dysfunction during ischemia. Our model has the advantage that numerous studies can be performed in the same animal, so that the results can be compared intraindividually.

Animals↗
PubMed1978

[Evaluation of the antigenicity of heart valve leaflets using inbred rat strain combinations (author's transl)].

Experiments with large, non-inbred animals yield no reliable evidence in the antigenicity of heart valves. With inbred strains of rats, however, it is possible to obtain evidence on the immunological reactions of heart valve leaflet transplants. Our experiments were undertaken on the inbred rat strains (CDR, LEW, CAP and BD5, using combinations as follows: syngeneic strain combination (CDF leads to CDF), weakly allogenic (RtH-1-identical) strain cimbination (LEW leads to CDF), strongly allogeneic (RtH-1-incompatible) strain combination (CAP leads to CDF). Strain BD5 was used for the control skin grafts. Either one or two heart valve leaflets were heterotopically intra-aortally transplanted. Sensitization was verified humorally by transplantation antibody titers and cellularly by subsequent donorspecific skin transplants. The following results were achieved: Allogeneic heart valve leaflets are antigenic. Intravascular grafting of one heart valve leaflet induces the same degree of sensitization as the grafting of two leaflets. In the RtH-1-identical system, sensitization is revealed only by subsequent skin grafting, whereas in the RtH-1-incompatible system, sensitization is humorally demonstrated as well. This indicates that in heart valve leaflet transplantation cellmediated reactivity is a more sensitive indicator than the humoral one. The greater the immunological difference is, the clearer the sensitization will be. In the strongly allogeneic system, the sensitization is even demonstrated humorally; skin grafts are rejected as "white grafts". Improved long-term results may be expected in allogeneic vital heart valve transplants if consideration is given to the HLA compatibility between donor and recipient; the appearance of delayed insufficiency could be greatly lessened or even deferred.

Animals↗