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Biomedical subjects

W Hauser

Publications and source records attributed to W Hauser.

At least 19 recordsLinked to original sources
PubMed1999

Megakaryocyte hyperplasia and enhanced agonist-induced platelet activation in vasodilator-stimulated phosphoprotein knockout mice.

Vasodilator-stimulated phosphoprotein (VASP), a substrate of cAMP- and cGMP-dependent protein kinases, is associated with focal adhesions, cell-cell contacts, microfilaments, and highly dynamic membrane regions. VASP, which is expressed in most cell types and in particularly high levels in human platelets, binds to profilin, zyxin, vinculin, F-actin, and the Listeria monocytogenes surface protein ActA. VASP is a member of the enabled (Ena)/VASP protein family and is thought to be involved in actin filament formation and integrin alphaIIbbeta3 inhibition in human platelets. To gain further insight into the in vivo function of this protein, VASP-deficient mice were generated by homologous recombination. VASP-/- mice demonstrated hyperplasia of megakaryocytes in bone marrow and spleen but exhibited no other macroscopic or microscopic abnormalities. Activation of platelets with thrombin induced a more than 2-fold higher surface expression of P-selectin and fibrinogen binding in VASP-deficient platelets in comparison to wild type. These data support the concept that VASP is a negative modulator of platelet and integrin alphaIIbbeta3 activation. Although the limited phenotypic differences between wild-type and VASP-/- mice suggested functional compensation of VASP by members of the Ena/VASP family, alterations in the expression levels of mammalian enabled (Mena) and Ena-VASP-like (Evl) protein were not detected. VASP-deficient mice may provide an interesting model system for diseases in which enhanced platelet activation plays a major role.

Animals↗
PubMed1996

Cloning of the VASP (vasodilator-stimulated phosphoprotein) genes in human and mouse: structure, sequence, and chromosomal localization.

The genes encoding the vasodilator-stimulated phosphoprotein (VASP) in human and mouse were isolated, and major parts were sequenced. In both species the gene is composed of 13 exons with conserved exon-intron positions. The mouse VASP cDNA sequence was deduced from the genomic sequence. The predicted amino acid sequence is 89% identical to the human protein. The high nucleotide sequence homology extends not only over the coding regions but also into the 3'-UTRs, indicating a possible function in mRNA targeting or regulation of translation. Prominent 5' CpG islands including multiple SP1 sites indicate a housekeeping function of VASP. Using cosmid DNA as a probe for fluorescence in situ hybridization, the human VASP gene was assigned to chromosome 19q13.2-q13.3, an extended region with homology to mouse chromosome 7. A sequence overlap of the VASP 5'-region with the telomeric end of a cosmid contig physically links the VASP gene with ERCC1. VASP is located about 92 kb distal to ERCC1 and about 300 kb proximal to the myotonic dystrophy protein kinase gene.

Amino Acid Sequence↗
PubMed1996

Periurethral abscess caused by a nonvenereological ulcer at the glans penis.

We report a case of a periurethral abscess caused by an ulcer at the glans penis successfully treated by chemotherapy and in addition by puncture of the liquified abscess. Diagnosis was made by ultrasound as the first-step imaging system, the exact time point for abscess puncture was determined by computer tomography. Periurethral abscess is a very rare pathological entity; to our knowledge there is no reported case of a nonvenereological ulcer as the primary lesion.

Abscess↗
PubMed1994

[Pattern of injuries in skiing worldwide. Can current guidelines for adjusting ski bindings reduce injuries in the future?].

World wide injuries show an overall reduction in skiing injuries. Updating the work of Hauser and Gläser (20) the average injury value declines from about 7 injuries per 1000 ski days in 1960 to 2 injuries per 1000 ski days in 1990. A stagnation can be reported for the past 5 years and no dramatic reduction is to be expected. Important, however is the trend of increasing knee injuries. As the risk for knee injuries was prevalent for female skiers (36, 15, 12) we also found a higher number of combined knee injuries especially including the medial collateral ligament (MCL). As the current binding adjustments do not focus on them, we are having a closer look about the advantages and disadvantages of each method. The final result is a suggestion for a radical change. By means of a new binding setting method and the demand for more responsibility to the skier we try to create a new skiing safety idea consisting of the setting table, a recommended binding release test and a gear binding. This is supposed to serve as the basis for a new safety approach.

Adolescent↗
PubMed1994

Brittleness of gallstones to lithotripsy: effect of physicochemical and ultrastructural characteristics.

Why some gallstones do not fragment easily to lithotripsy is unclear. The aim of the present study was to determine gallstone factors associated with resistance to fragmentation. Seventy-six cholesterol rich gallstones were subjected to physical evaluation, in vitro computed tomography, chemical analysis by infra red spectroscopy, and ultrastructural studies (of 26 matched stones) by scanning electron microscopy and energy dispersive X-ray microanalysis. In vitro lithotripsy was performed with the Siemens Lithostar Plus machine at a constant energy level. Of 76 stones, 33 required > 1000 shocks for effective fragmentation (largest diameter < or = 5 mm); they had significantly higher maximum diameter (P < 0.001), volume (P < 0.001), weight (P < 0.001) and lower stone density distribution (SDD) index (P < 0.05) and lower calcium bilirubinate content (P < 0.001) than those requiring < or = 1000 shocks. Large (> 15 mm; P < 0.05), round stones (P < 0.02) and gallstones with SDD index of < 50 HU (P < 0.02) and gallstones with SDD index of < 50 HU (P < 0.05) were more difficult to fragment. Clinical application of these parameters may help in better selection of patients for this non-surgical mode of therapy for gallstones.

Chemical Phenomena↗
PubMed1991

[Treadmill versus field trial. Movement analysis and pressure distribution in the athletic shoe].

Our current knowledge on interactions between runner and runningshoe is mainly based on treadmill measurements. In order to reveal stress load and adaptation on playing surfaces it was necessary to develop a combined measuring device out of 3-D video motion analysis and portable pressure measurement system. By means of a motor driven cart moving parallel to the subject with comparable position of cameras to the treadmill test it was possible to set up an identical trial for track and field. 12 subjects (male, age 24-32, size 9) were tested at a speed of 2.8 m/s. The varying conditions were treadmill and grass and two different constructed running shoes. 200 cycles and over 1000 steps were analyzed. The quantitative analysis of 37 parameters describing the contact phase was performed using the wilcoxon test for paired samples.-A qualitative comparison of running styles was introduced by using angle-angle-diagrams (knee and ankle by 3-D data) similar to those first described for 2-D by P.R. Cavanagh in 1973. It showed a huge interindividual variability under same conditions. Comparing the angle-angle-diagrams for the four different running conditions it was possible to classify them into three characteristic groups: non-adaptors, surface-adaptors and shoe-adaptors. Comparing track and field to treadmill measurements significant differences were found for the knee at impact: On treadmill the initial knee angle was 4.6 degrees more extended at a 13% higher angle velocity and a 30% higher angle deceleration (sig. p less than 0.05). A 7.3% higher impulse was found on grass at a 5.9% higher step length. No difference in maximum pressure was found. These results show that adaptation is performed mainly by the knee. Changing the motion pattern the knee seems to be capable of homogenizing the different stress loads to the foot. Comparing the running shoes significant differences were found in the motion of the ankle: a controversial behaviour was found to be on treadmill and grass. The pressure data revealed significant differences for the treadmill test to be in the heel area, for grass in the arch area. This points to an--up to now--unknown importance of the arch on unplain surfaces that are obviously influenced by the construction of the shoe and are not accessible by treadmill tests. The described different behaviour of shoes in treadmill and track and field tests points out the reduced validity of single treadmill tests.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Increasing infertility in myotonia dystrophica Curschmann-Steinert. A case report.

A 26-year-old male came to our andrologic out-patient clinic because of his desire to have children. Preliminary examinations revealed a varicocele left and a subclinical varicocele right. Testicular volume was smaller than normal, and spermiogram values were already poor (vitality, motility and morphology). Basic hormones were normal. The anamnesis gave no information on hereditary disorders. Surgical treatment of the varicocele did not bring the desired outcome. A testicular biopsy showed Leydig cell hyperplasia with strongly reduced spermiohistogenesis. In a renewed and extensive anamnesis, the patient revealed that he suffers from myotonia dystrophica Curschmann-Steinert. This disorder causes sclerosis of the tubuli seminiferi contorti, which can ultimately lead to azoospermia.

Adult↗
PubMed1990

[Ski boots versus the knee joint. 2: What produces the forward leaning position of the ski boot?].

In contrast to the drop in the incidence of fracture of the lower leg that has been observed in recent years, the incidence of knee injuries has not decreased in skiing. There has even been a relative increase of severe knee lesions and isolated ACL ruptures, prompting us to conduct a comprehensive study of the causes of this phenomena. The goal of part 2 of the study was to comprehensively examine the forward movement in skiboots in the lab and on the slope. Studying nine beginners and eight experts, we found a 20% (sign. 0.05) lower forward-lean capability for the beginner group in the same boot. A randomized study with crossover design conducted on the slope, where we equipped 16 skiers with either soft or stiff boots for the duration of five ski days, revealed the learning behaviour and forward position on the slope depending on the boot. The pupils became definitely less adept at learning if they were required to wear stiff skiboots and showed a sign, lower forward flex angle. A skiiing style in backward lean position was adopted and supported by the fixed backward spoiler. Therefore another study was necessary and will follow (part 3) to examine the effect of a stiff backward spoiler and skiing in a backward lean position. In consideration of the facts known up to now, it is concluded that to improve safety in skiing recommendations must be given as to which boot to choose, according to the skiing level. In addition, the setting of safety bindings must consider the type of skiboot used.

Biomechanical Phenomena↗
PubMed1990

[Ski shoe versus knee joint--3: Risk for falling backward].

In contrast to the drop in the incidence of fractures of the lower leg that has been observed in recent years, the incidence of knee injuries has not decreased in skiing. There has even been a relative increase of severe knee lesions and isolated ACL ruptures, prompting us to conduct a comprehensive study of the causes of this phenomena. The goal of the study was to develop a new measuring device for alpine skiing research by combining motion analysis, pressure and force measurement, comprehensive examine the forward/backward movement in skiboots in the lab and by means of telemetry on the slope (Skiboot versus knee joint part 1/Sportverlerletzung. Sportschaden 3, 1989, pp. 149-161) and to come up with a proposal for a new safety concept to reduce the high number of knee injuries in alpine skiing in the future. The first study was devoted to the forward movement in skiboots (Skiboot versus knee joint part 2/Sportverletzung. Sportschaden 4, 1990, pp. 1-13). The results showed that a skiing style in backward lean position was adopted by skiers wearing boots with a stiff forward flexion and was supported by the fixed backward spoiler. In order to quantify the influence of the backward spoiler a special skiboot was constructed allowing the rear spoiler to give way at a variable, defined stiffness and register the angular displacement and horizontal force Fh. The results showed most clearly that even a medium rear spoiler resistance will sign, reduce the peak force values by a factor of 5.5. The acceleration at the knee joint level is significantly higher (factor 1.6, p less than 0.05) in case of a rigid spoiler. The lab tests could be confirmed on the slope (sign. reduction of max. force by factor 8). It also proved that normal skiing can be performed in such a boot without limitations. In consideration of our facts it is concluded that the principle of safety bindings must definitely apply in future in equal measure also to the ski boot. As a proposal for future safety ski boot, that allowed for the first time the rear part to give way after a certain amount of force (adjustable preload). The backward release bindings, which can often produce dangerous malfunctions if a strong force acts on them for a short period of time, could thus be complemented by a safety system in the boots. In all probability this would be a contributing factor to reducing the high incidence of knee injuries in skiing.

Adult↗
PubMed1990

Alkali citrate for preventing recurrence of calcium oxalate stones.

The use of alkali citrates for preventing the recurrence of calcium oxalate stones was investigated in two trials. In trial I, alkali citrates were given continuously for 18 months to 8 patients who had shown a tendency to recurrent stone formation. In trial II, 12 similar patients were given intermittent therapy for 12 months. The expected changes in urine chemistry were checked at intervals of 3 months. Recurrent stone formation (2 episodes) was observed in only 1 patient (in trial II) during alkali citrate administration; before therapy this patient had suffered an average of 10 attacks of stone formation annually. In the light of the experience gained in these trials, continuous administration of alkali citrates is recommended; the duration of treatment should be tailored to individual needs, but it should not be prolonged indefinitely. Besides having well-attested effectivity of stone prevention, this mode of therapy carries a relatively low incidence of side effects.

Adult↗
PubMed1989

[Skin boot versus knee joint--a sports medicine, orthopedic and biomechanical problem].

In contrast to the drop in the incidence of fractures of the lower leg, or tibia, that has been observed in recent years, the incidence of knee injuries has not decreased in skiing and there has been a relative increase in the frequency of severe knee lesions and of the isolated rupture of the cruciate ligament, prompting us to conduct a comprehensive study of the causes of these phenomena. It was found necessary to develop a innovative method of measurement to analyse the patterns of movement and stress to which the knee injuries were attributed. By combining and synchronizing movement analysis, measurement of pressure distribution and measurement of force it became possible to perform a detailed analysis of the forward/backward movement in the ski boot in the laboratory and also on the course by telemetry (part 1). The first two studies were devoted to the forward lean in the ski boot (part 2). Basing on movement analysis and simultaneous determination of pressure distribution along the lower leg, the influence of different ski boot models on the Vorlage, or forward lean, movement of beginners and very experienced skiers was studied. An important result of the laboratory experiment was that whereas a ski boot can be moved without difficulty into a strong forward lean position of the skier by an experienced sportsman, a beginner can only assume a forward lean with 20% less inclination (this being a significant difference). In other words: the range of the freedom of movement in such a boot is markedly limited. The assumption that in ski amateurs such a ski boot would promote skiing in backward lean position, was confirmed by studies on the course (part 3). The pupils became definitely less adept at learning if they were required to wear a stiff ski boot; analysis of movement showed that the forward lean angles were clearly smaller and that the skiers adopted a skiing style in backward lean position that exercised an undue strain on the knees. The other two studies, therefore, focussed mainly on the backward movement in the ski boot. Specifically, the fixed rear spoilers of the modern ski boots are accused of contributing to the rupture of the anterior cruciate ligament if the skier lands on the tail ends of the skis after a jump or fall in backward lean position ('big bump, flat landing' syndrome).(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMed1988

[Factors affecting the pressure distribution underneath the foot sole in ski boots].

The determination of pressure patterns underneath the footsole inside skiboots, may reveal reasons for footpain and injury risk. In our study, a new developed 72 point measuring mat was used in 5 different skiboots. Data were collected in 10 subjects in different forward flexion positions. In addition a determination of the pressure distribution over the instep was done by means of single measuring points. The results proof, that a proper adapting along the dorsum of the foot does lower the forefoot load during flexion. A tightly closed and well adapted boot will lead to a significant reduction of the total load on the footsole. High shaft models show similar pressure patterns even at earlier forward flexion angles. A pressure related discrimination between rear entry and traditional boots, that was found along the tibia, was not the case underneath the footsole. The force transmission is mainly performed along the shaft of the boot. The effect of orthotics designed mainly to support steerability of the ski, is therefore doubtful. The results may help to improve our knowledge of the interaction between boot and skier and lead, together with future field research, to a reduction of equipment related injuries.

Biomechanical Phenomena↗
PubMed1987

[Measuring pressure distribution on the human tibia in ski boots].

Pressure distribution inside shoes is of great importance for orthopaedic and biomechanical inquiries. Especially in sports, safety and comfort depend essentially on this quantity, which also determines whether a shoe is well suited for a certain discipline. Therefore, the measurement of pressure distribution allows detailed and objective statements about these factors. Using a set of newly developed thin and highly flexible measuring mats and the corresponding electronic equipment, such statements have become possible. First results with this method were obtained in alpine skiing. 8 different types of ski boots (sizes 5 and 8) worn by 14 subjects were tested on different foreward leans and temperatures using 7-point measuring mats (2 cm2/point) fixed between the boot shaft and the front of the lower leg of each leg. Additional measurements on three different types of boots using a 3 x 24-point mat (1 cm2/point) for the lower leg, as well as measurements underneath the foot with a 14-point (2 cm2/point) and a 80-point (1 cm2/point) mat were performed. A complementary determination of the force at the heel element of a ski binding and a registration of muscular activity (EMG) helped in the interpretation of the results. Some field research using telemetry completed our study. Considerable variations between different boots were found in value and location of pressure maxima. Traditional boots show high pressure values over the instep at foreward leans of 35 degrees and a rise of pressure underneath the forefoot while fixing the buckles, whereas minimal pressure over the instep, no compression of the forefoot and a pressure maximum near the upper end of the shaft are observed in rear entry boots. The force at the heel-important for binding release-varies widely between different boots at the same foreward lean. There was no asymmetry between the pressure distributions of right and left. The pressure distributions for different subjects measured in the same boot were very similar. The temperature dependence of pressures is strongly influenced by the construction principle of the boot: If shaft stiffness is caused by deformation of plastics, boots become much stiffer at the freezing point than they are at room temperature. Well-suited ski boots should cause low pressure over the instep and show a relatively low maximum in the upper part of the shaft, in order to allow a good transmission of torque, which is necessary for a safe binding release and easy skiing without fatigue. The shaft stiffness must not depend strongly on temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1987

[Dynamic measurement of pressure distribution with flexible measuring mats--an innovative measuring procedure in sports orthopedics and traumatology. Development--use--value].

The results of this study provide the basis for an on-target use of measurement of pressure distribution with flexible mats in sports orthopaedics and traumatology and adjacent overlapping fields. Dynamic measurement of pressure distribution using a flexible mat as a capacitor can yield valuable additional information not available so far in this form, on the static and dynamic stress acting on the human locomotor system. In the future this method can be used to prevent injuries and to optimise performance in many disciplines of sport and will make a significant contribution to optimised treatment concepts with pressure-adjusted shoes or insoles, as well as to the control of functional surgery results in traumatology. The fundamentals are presented via a detailed description of the development, standardization and testing of this innovative measuring method. The questions of applicability, practicability and information supplied are discussed on the basis of extensive studies on reproducibility, on the amount of time and technical effort required for each measurement, and on a critical comparison with other methods. For the two fields of application presented here it was possible to standardize the working procedure enabling a largely problem-free application in practice. The first useful results were obtained in sports orthopaedics (alpine ski boots and sportshoe design). By applying the measuring of pressure distribution in alpine ski sports the influence the construction of ski boots on the stress exercised on the human leg could be objectively quantified in man for the first time. Marked differences were found between models where the heel can be turned down on entering, to conventionally fastened ski boots. This, as well as the results on the influence temperature, height of shaft and shaft stability or rigidity on the pressure distribution along the tibia, provide the basis for a new guideline for the testing of ski boots. A new method was developed for the quality testing of shoes, insoles and sport shoes. This method enables for the first time dynamic pressure measurements inside the shoe and under the foot within the shoe. First results have been obtained with different insoles and arch supports or instep-raisers, or with different shoe constructions in general. These results are discussed in respect of their importance for an assessment of the stress exercised on the human body, for a timely detection of unfavourable stress distribution, and for optimizing the performance by means of selecting the appropriate material and suitable design and construction.

Athletic Injuries↗
PubMed1980

The College of American Pathologists Phantom Series--an assessment of current nuclear imaging capabilities.

Twelve sets of emission phantoms were distributed semiannually to laboratories of nuclear medicine from 1973 through 1978. This survey aimed to create a national peer group within which it might become possible to compare and standardize nuclear imaging technics, and to evaluate and define the current state of the art in a clinical setting. Results were analyzed in terms of sensitivity (percentage of true-positives), nonspecificity (percentage of false-positives), and performance indices (true-positive/false-negative ratios) for conventional gamma cameras and for rectilinear scanners. The chief determinants of target detectability proved to be target-to-surface depth, target diameter, and intrinsic target contrast. Operational variables and instrument type produced relatively minor effect upon subscriber performance. Gamma cameras tended to show slightly more sensitivity than rectilinear scanners, but were somewhat troubled by nonspecificity. Improvements in the intrinsic resolution of second- and third-generation gamma cameras increasingly employed since 1975 showed negligible impact on performance indices. A consideration of the overall survey performance indices. A consideration of the overall survey performance permits the beginning of a quantitative estimate of current detection capability in day-to-day nuclear imaging.

Evaluation Studies as Topic↗