Biomedical subjects

M Wimmer

Publications and source records attributed to M Wimmer.

138 records · Page 8Linked to original sources

PubMedDate not supplied

Doppler flow profiles in the right and left pulmonary artery in children with congenital heart disease and a bidirectional cavopulmonary shunt.

The systolic and diastolic Doppler tracings in the right and left pulmonary artery were analyzed in 10 patients with complex cyanotic congenital heart disease, aged 6 months to 12 years (median 3 years), after employment of a bidirectional cavopulmonary shunt. The postoperative interval ranged from 2 weeks to 1.7 years (median 1.3 years). In children with pulmonary atresia or severe pulmonary stenosis with minimal antegrade pulsatile pulmonary blood flow Doppler echocardiography confirmed a systolic and diastolic bidirectional shunt from the vena cava superior to both pulmonary arteries. In children with pulmonary stenosis, Doppler echocardiography confirmed a systolic shunt only to the right pulmonary artery and a diastolic bidirectional shunt into both pulmonary arteries. As the left pulmonary artery was perfused by the pulsatile transvalvular flow it was difficult to detect a concomitant systolic Glenn-related flow in those patients. Quantitative analysis of the diastolic Doppler tracings revealed a significant difference in the velocity time integral in the right and left pulmonary artery indicating a dominant right lung perfusion in diastole.

Arteriovenous Shunt, Surgical↗

PubMedDate not supplied

Iron supplementation in children after cardiopulmonary bypass for surgical repair of congenital heart disease.

A controlled study was carried out to evaluate the effects of postoperative iron therapy on iron status in anemic children after cardiopulmonary bypass. The patients were 8 boys and 9 girls (mean age 6.5 years) who underwent elective closure of atrial septal defect, secundum type. On postoperative day 9, patients were randomly assigned to either iron supplementation with iron sulfate 5 mg/kg until day 56 or to a control group. Hemoglobin, reticulocytes, transferrin saturation, free erythrocyte protoporphyrin, and ferritin were measured, the final outcome measure being postoperative iron status on day 56. The treatment group showed higher transferrin saturations (33.5% versus 18.0%), smaller decreases in ferritin level (+3.0 versus--13.7 ng/ml), and a lower incidence of depleted iron stores (0/8 versus 5/9) than the control group (all data: P < 0.05). Anemic children after cardiopulmonary bypass for surgical repair of congenital heart disease thus benefit from iron supplementation within the first postoperative weeks.

Anemia, Iron-Deficiency↗

PubMedDate not supplied

Therapeutic strategy in a 9-month-old child with pulmonary sling: need for bronchoscopic evaluation.

A 9-month-old child presented suffering from repeated severe infections of the lower respiratory tract. Bronchoscopy revealed a tracheal stenosis, suggestive of a vascular anomaly of the great arteries. A second significant stenosis of the left main stem bronchus was observed that was suspected to be due to a ligamentum arteriosum. Heart catheterization confirmed the diagnosis of an abnormal origin of the left pulmonary artery (pulmonary sling). Based on the bronchoscopic and angiographic findings a pulmonary ring was suspected. A dissection of the ligamentum arteriosum was performed. At readmission 4 weeks postoperatively the child was asymptomatic and the left main bronchus was patent.

Bronchi↗

PubMedDate not supplied

Novel route to fatigue-resistant fully sintered ultrahigh molecular weight polyethylene for knee prosthesis.

The role of entanglements in obtaining a homogeneous product of ultrahigh molecular weight polyethylene (UHMW-PE) has been explored. Studies performed in this report show that a disentangled state before melting is a prerequisite to obtain homogeneous products of an intractable polymer like UHMW-PE. The disentangled state is obtained directly from the reactor by controlling the polymerization conditions or in the solid state when there is enhanced chain mobility along the c axis of a unit cell. The disentangled state is maintained in the melt over a period of time, invoking implications in polymer rheology. This approach is applicable to polymers in general. The homogeneous fully sintered UHMW-PE, obtained for the first time, shows a considerable decrease in oxygen permeability and an increase in toughness and fatigue resistance. Such homogeneous products of UHMW-PE are beneficial in highly demanding applications, especially in knee prosthesis, where the polymer is used as an inlay between the human bone and a metal or ceramic part, which slides against the polyethylene component during normal gait.

Knee Prosthesis↗

PubMedDate not supplied

[Size and shape of commercially available polyethylene particles for in-vitro and in-vivo-experiments].

AIM: The longevity of total hip arthroplasty is sometimes limited by osteolysis and aseptic loosening. Aseptic loosening may be caused by the biologic reaction to polyethylene wear particles. Particles of less than 1 micro m diameter are of particular importance. These particles are not easily available for experimental use. METHOD: We performed a morphologic analysis of commercially available, very small polyethylene particles (Ceridust(R)) in order to determine the specific size distribution. We measured 1 978 particles. Size analysis was performed using an electron microscope. Particle size was described as the equivalent circle diameter (ECD). Particle morphology was described as feret ratio. In addition, Ceridust(R) particles were compared to different particles stemming from a hip simulator experiment. RESULTS: More than 35 % of the particles were less than 1 micro m in size. The particle size was 1.75 micro m +/- 1.43 micro m (median 1.42 micro m). The minimum was 0.06 micro m, the maximum was 11.06 micro m. The feret ratio was 0.58 +/- 0.17 (median 0.63). The minimum was 0.07, the maximum was 0.93. The majority of Ceridust(R) particles had a rough surface. Compared to polyethylene particles stemming from a hip simulator experiment, Ceridust(R) particles had a rougher surface, were less longitudinal, and had a more even size distribution. CONCLUSIONS: The pure, commercially available polyethylene particles analyzed here are suitable for in vitro and in vivo experiments due to their easy availability, minor costs, and large fraction of very small particles.

Biocompatible Materials↗

PubMedDate not supplied

[Effect of timing of surgery on the intellectual and psychosocial development of children with tetralogy of Fallot].

Chronic hypoxemia in patients with Tetralogy of Fallot may influence intellectual and social development. Even though the physical situation is the most important factor for the time of operation, psychosocial aspects should be considered as well. 24 children underwent intelligence tests and questionnaires, 13 of them having had surgery in early infancy, 11 between 7 and 11 years of age. No significant difference was noted between the two groups concerning early childhood development and mean IQ. Early operation does appear to improve the social situation. Such children are able to participate in kindergarten, start school in time and pass through school without delay. These results suggest a possible beneficial relief of the stressed situation of the whole family.

Adolescent↗

PubMedDate not supplied

[Bacterial endocarditis in childhood].

BACKGROUND: Bacterial endocarditis in childhood is a rare but serious disease. The group of children with congenital heart disease at risk to develop bacterial endocarditis increases, because more children survive with advanced medical and surgical management. Rheumatic Fever as predisposing heart disease decreases and is of reduced importance. PATIENTS: From 1983 to 1993 16 patients in the age of 0.3 to 17.6 years (mean 10.6 years) were received by the Department of Pediatric Cardiology of the University Children's Hospital Vienna with the diagnosis "bacterial endocarditis". A congenital heart disease was known previously in 13 cases: 4 children had VSD, 2 children had Tetralogy of Fallot, 1 child had a single ventricle and an infundibular pulmonary stenosis, 4 children had pulmonary atresia, 1 child had a cleft of the mitral valve, and 1 child had a coronary artery fistula. Moreover, 1 child had a mitral valve prolapse with valvular regurgitation as a consequence of Marfan-Syndrome. 6 children with congenital heart disease had been treated surgically previously. METHODS: Medical data of all patients with the diagnosis of "bacterial endocarditis" between 1983 and 1993 were analysed. It was this period when echocardiography was used for the first time to contribute to diagnosis and course control. RESULTS: In 11 of 16 cases positive blood cultures were obtained. Mostly Streptococcus viridans (4 cases) and Staphylococcus aureus (3 cases) were isolated. During the parenteral therapy with antibiotics 9 children suffered as a side effect from a drug induced fever and/or decreasing leucocytes and thrombocytes or a rash. In addition to the antibiotic therapy 8 children were treated surgically. One child died immediatly after the operation. 15 of the 16 patients with endocarditis survived. CONCLUSIONS: With children with known heart disease the recommendations for the prevention of bacterial endocarditis have to be strictly followed and every long ongoing feverish disease has to be carefully examinated.

Adolescent↗

PubMedDate not supplied

[Cognitive development of children and adolescents after correction of transposition of great vessels].

BACKGROUND: To study the effect of transposition of the great arteries on later cognitive functioning. PATIENTS: Twentyeight children and adolescents underwent psychometric testing 3.5 to 13.7 years following operation. METHODS: A battery of intelligence, attention and visual memory tasks as well as the Draw-a-Man-Test were administered. Parents completed standardized questionnaires on developmental milestones. RESULTS: Both, mean verbal (93 +/- 15) and performance IQs (97 +/- 21) were normal. The length of interval between operation and psychologic test but not age at repair was a significant predictor of intelligence quotient. Half of the children (9/18) showed attention deficits, 7/11 (64%) were identified as suspect of brain dysfunction. Performance on the Draw-a-Man-Test disclosed 12 (43%) as slightly mentally retarded. CONCLUSIONS: (1) Cognitive functions in children with TGA are more impaired than suggested by the results of intelligence tests. (2) Psychological and neurologic follow-up should be mandatory from early on. (3) Previous studies have overestimated children's intelligence due to unrecognized changes of test norms.

Adolescent↗

PubMedDate not supplied

Premarital childbearing in northwest Kenya: challenging the concept of illegitimacy.

A number of African countries, including Kenya, have experienced a marked rise in births among unmarried women. In Western countries, reproduction outside of marriage is assumed to be illegitimate and a social problem. One hypothesis used to explain the increasing incidence of premarital fertility in Africa is a breakdown of traditional social controls by the extended family over the sexual behavior of adolescents. A competing hypothesis suggests that unmarried women use sexual relations to achieve goals such as marriage. Among Turkana pastoralists of northwest Kenya, we find a pattern of premarital birth that fits either hypothesis only loosely. Premarital fertility among the Turkana is both widespread and culturally acceptable, with over 30 per cent of women having at least one child prior to marriage. Although women with premarital births initiate childbearing on average one year earlier than women with only marital births, women's marital status does not influence the length of the interval between first and second births. Marriage among the Turkana is not a social trigger for the onset and continuation of reproduction or a means to legitimate reproduction. Marital status of the parents simply determines the custody of a child. In a premarital birth, the father pays a set fee to the mother's family, and the custody of the child remains permanently with the mother's family. If the parents later marry, the father must purchase custody of the child by another fee at that time. Since the Turkana have experienced few effects of modernization, the existence of such a practice suggests that cultural factors must be taken into account before assessing premarital fertility in Africa as a social problem.

Adolescent↗

PubMedDate not supplied

Morphometric and ultrastructural findings on human vestibular ganglion cells.

Eight human temporal bones (4 patients) were fixed within 2 h after death by perilymphatic perfusion through the oval and round windows. After preparation, 30-micron-thick sections were cut for light microscopy and ultrathin sections for ultrastructural evaluation. Under the light microscope, the diameter, the circumference and the area of the vestibular ganglion cells were measured. The data were statistically analyzed. The histograms of cell measurements showed two maxima. When observing the diameter of cells, one was at 40 microns and the other at 28 microns. Under the light microscope, we could distinguish two cell types, which mainly differed in size and content of granules in the cytoplasm. Ultrastructurally we identified also two cell types: larger cells with many mitochondria, dark clusters of endoplasmic reticulum and a varying amount of dark-stained lysosomes in the cytoplasm and smaller cells with only few mitochondria, no lysosomes and an extended rough endoplasmic reticulum. None of the ultrastructurally analyzed ganglion cells were myelinated.

Cell Nucleus↗

PubMedDate not supplied

[Rotational bending test of hydroxylapatite plasma-coated models of TiAl6V4].

Plasma spraying of hydroxyapatite coatings onto hip joint and knee endoprosthesis implants and dental implants is state of the art. Nevertheless, there is still a lack of data on the long-term behavior of such coatings. Using the rotating-bending test DIN 50,113 it is shown that parts plasma-sprayed with 200 microns OSPROVIT exhibit delamination only after fracture of the metallic component. At a load of 400 MPa more than 1.10(9) loading cycles were achieved.

Alloys↗

PubMedDate not supplied

Aspiration cytology, immunocytochemistry and electron microscopy of a malignant peripheral neuroectodermal tumor. A case report.

The findings of fine needle aspiration (FNA) cytology, immunocytochemical staining and electron microscopy (EM) in a case of malignant peripheral neuroectodermal tumor (PNET) presenting as a soft tissue mass in the lateral abdominal wall are reported. The immediate evaluation of the aspirate revealed cells of a small round cell malignant tumor. To provide a specific preoperative diagnosis, additional cytologic material was aspirated for immunocytochemical and ultrastructural investigations. While the results of EM were nonspecific, allowing only the exclusion of other small round cell malignancies, immunocytochemical staining of the aspirate was suggestive of a PNET. The diagnosis of PNET was corroborated by histopathologic and immunohistochemical findings. This case indicates that an exact preoperative categorization of small round cell malignant tumors can be made by FNA biopsy in otherwise equivocal cases when immunocytochemical and ultrastructural techniques are also utilized.

Abdominal Muscles↗