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Biomedical subjects

M Hasler

Publications and source records attributed to M Hasler.

At least 19 recordsLinked to original sources
PubMed2004

[Body condition and frequency of ovarian cysts in Brown Swiss cows during the first 40 days of lactation].

For this investigation 50 Brown Swiss cows from 21 different farms were used. Twenty-five peripartal overconditioned cows (back fat thickness > 38 mm) were compared with 25 peripartal not overconditioned animals (back fat thickness < 38 mm). On days 20, 30 and 40 post partum the ovaries were examined sonographically and 10, 15, 20, 30 and 40 days after calving plasma concentrations of progesterone and 17-beta estradiol were determined. In peripartal overconditioned animals 12 ovarian cysts were found while only one cyst was present in not overconditioned cows (P < 0.05). At first examination all ovarian cysts were classified by ultrasound as follicle theca cysts (progesterone < 0.5 ng/ml plasma). Follow examinations resulted in 3 cysts which persisted as theca cysts while 8 cysts became luteinized and 2 cysts completely regressed. There was no indication of increased plasma progesterone and/or estradiol concentrations in overconditioned cows with higher fat deposit before of ovarian cysts had occurred.

Adipose Tissue↗
PubMed2003

Persistent clusters in lattices of coupled nonidentical chaotic systems.

Two-dimensional (2D) lattices of diffusively coupled chaotic oscillators are studied. In previous work, it was shown that various cluster synchronization regimes exist when the oscillators are identical. Here, analytical and numerical studies allow us to conclude that these cluster synchronization regimes persist when the chaotic oscillators have slightly different parameters. In the analytical approach, the stability of almost-perfect synchronization regimes is proved via the Lyapunov function method for a wide class of systems, and the synchronization error is estimated. Examples include a 2D lattice of nonidentical Lorenz systems with scalar diffusive coupling. In the numerical study, it is shown that in lattices of Lorenz and Rossler systems the cluster synchronization regimes are stable and robust against up to 10%-15% parameter mismatch and against small noise.

Algorithms↗
PubMed2000

Hierarchy and stability of partially synchronous oscillations of diffusively coupled dynamical systems

The paper presents a qualitative analysis of an array of diffusively coupled identical continuous time dynamical systems. The effects of full, partial, antiphase, and in-phase-antiphase chaotic synchronizations are investigated via the linear invariant manifolds of the corresponding differential equations. The existence of various invariant manifolds, a self-similar behavior, and a hierarchy and embedding of the manifolds of the coupled system are discovered. Sufficient conditions for the stability of the invariant manifolds are obtained via the method of Lyapunov functions. Conditions under which full global synchronization cannot be achieved even for the largest coupling constant are defined. The general rigorous results are illustrated through examples of coupled Lorenz-like and Rossler systems.

Journal Article↗
PubMed1978

[Thrombocyte migration test as a sensitive tolerance test before platelet substitution (proceedings)].

Thrombocytopenic patients refractory to random-donor platelet support can usually be substituted by platelets obtained from donors identical with respect to HLA-A and -B antigens [1]. Since such "full-house" identity is rarely available, reliable cross-match tests (CM) are needed in order to pick out donors compatible in spite of HLA non-identity. By use of the thrombocyte migration test (TMT), DUQUESNOY et al. have shown that antiplatelet antibodies may exert an inhibitory effect on platelet migration. Therefore, we have explored this test system for its efficiency as CM compared with the "long-time" lymphocyte cytotoxicity test (LLT). Of 8 sera from polysensitized patients, serial dilutions were performed and simultaneously tested by TMT and LLT with cells obtained from the same control individuals. The sensitivity of TMT exceeded LLT by 2-4 dilution steps in all sera tested. Moreover, 9 patients with incompatible transfusion responses to single-donor platelets in spite of negative LLT had the following results in TMT with pre-transfusion sera: 5 positive (i.e. migration inhibition), 1 negative: enhanced migration was observed 3 times. This phenomenon of enhancement remains to be clarified, since low titers of anti-HLA-antibodies do not cause enhanced platelet migration. Repeated transfusion of platelets obtained from the same donor may cause antibody production against leukocytic antigen not shared by platelets, leading to "false-positive" LLT. 2 patients were successfully substituted with platelets from HLA/MLC-identical siblings in spite of positive LLT, but with negative TMT; in 2 cases with unrelated HLA-A and -B identical donors, TMT results were inconsistent.

Blood Platelets↗
PubMed1976

Ultrastructure of articular cartilage of achondroplastic mice.

Articular chondrocytes of achondroplastic mice (cn/cn) resemble ultrastructurally those of their non-achondroplastic siblings (Cn/Cn or Cn/cn), except for premature deposition of glycogen and a tendency to undergo regression. The latter may be slight or extreme. The ultimate cause of the vulnerability of the chondrocytes and the cause of the heterogeneity of the reaction could not be determined with the method employed. Nevertheless, increased vulnerability accounts for cell death under conditions which are usually not injurious, and which may be either physiologic or altered by endogenous or exogenous factors.

Achondroplasia↗
PubMed1976

Articular cartilage of diabetic Chinese hamsters.

Investigations were carried out in order to determine whether animals with spontaneous diabetes are prone to develop skeletal lesions comparable to those found in diabetic human subjects. The present report deals with the ultrastructure of the cartilage of the hip joint of diabetic Chinese hamsters and nondiabetic control animals. In the diabetic animals, chondrocytes of the femoral head showed atrophy of the endoplasmic reticulum, bizarre mitodhoncria, and huge lipid inclusions, which are changes suggestive of disturbed function.

Animals↗
PubMed1975

Submicroscopic response of articular chondrocytes to a cholesterol-containing diet.

10 days' to 3 months' consumption of a diet containing 4% cholesterol causes a minor and transitory stimulation of articular chondrocytes of mice. The transitory disturbance is accompanied by a more permanent increase in glycogen, by abnormal deposition of cytoplasmic lipid and by an increase in the fibrillarity of the pericellular matrix. The changes are consistent with the failure of the cholesterol diet to influence the course of osteoarthrosis if fed to mice from an early age through life.

Animals↗
PubMed1975

[Results of primary and combined radiotherapy of mouth carcinomas (tongue, tonsil, maxilla, mandible, palate, floor of the mouth cheek mucosa)].

Responses to highvoltage radiotherapy of 320 patients with carcinomas of the oral cavity are discussed. Five year survival rate according to the stage of the, disease were the following ones: in carcinoma of the anterior 2/3 of the tongue and floor of the mouth 20-60%, buccal mucosa, upper and lower jaw 30-50%, base of the tongue 26% and tonsil 30-100%. After simultaneous irradiation of the efferent lymphatics in parimary N0 patients, whose primary tumor subsequently was under control, a significantly lower frequency of metastases to the lymph nodes was found than without coirradiation of the lymph flow. Clinically verifiable metastases of the lymph nodes are also controllable to a high percentage by radiotherapy alone: Only in a little more than five per cent of the primary N1-3 patients with the parimary tumor being under control, additional metastases of the lymph nodes developed later on. The complication rate was 6.8 per cent. Most frequently, osteonecrosis was involved, indeed occurring chiefly in cases, where a primary skeletal manifestation of the tumor already was existing.

Bone Neoplasms↗