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Biomedical subjects

P Wirtz

Publications and source records attributed to P Wirtz.

At least 19 recordsLinked to original sources
PubMed1997

[Septic myocardial aneurysm in mitral valve endocarditis. Clinical and pathological-anatomical findings].

HISTORY AND CLINICAL FINDINGS: A 68-year-old woman was hospitalized because of fever and tiredness for 3 months. Her general condition was clearly impaired. She had a mild fever of 38.5 degrees C and on auscultation a 3/6 systolic murmur, maximal parasternally in the 3rd intercostal space, transmitted to the apex. There were distant râles over both lungs, the neck veins were distended and there was ankle oedema. INVESTIGATIONS: C-reactive protein was raised to 17.3 mg/dl (normal up to 0.9 mg/dl), WBC count 19,300/microliter. beta-haemolysing streptococcus (S. agalactiae) was grown in the blood culture. The ECG showed sinus tachycardia (rate of 98/min) and transthoracic echocardiography demonstrated a small pericardial, enlarged ventricles, marked mitral regurgitation and a large vegetation on the posterior mitral leaflet, as well as a 3 x 4 cm mass in the posterior wall of the ventricle, originating from the posterior mitral valve ring and communicating with the vegetation on the mitral valve. The posterior mitral leaflet was perforated. TREATMENT AND COURSE: As endocarditis of the mitral valve with a complicated course was suspected-abscess of the posterior mitral valve ring and septic myocardial aneurysm with associated pericarditis and haemodynamically insignificant effusion-she was transferred to the intensive care unit where she died suddenly of circulatory arrest only 30 min after transfer. Autopsy confirmed the echocardiographic findings. CONCLUSION: Paravalvular abscess in the course of mitral valve endocarditis is rare, but should be looked for at transthoracic echocardiography so that any necessary surgical intervention can be undertaken early.

Aged↗
PubMed1995

The development of compensatory hypertrophy in the plantaris muscle of the rat.

The aim of this investigation was to study the time course of compensatory hypertrophy (CH) over a seven week period after its surgical induction in the lower limb of the rat. CH of the left plantaris muscle of the rat was induced by denervation of the ipsilateral gastrocnemius and soleus muscles. Muscle fibres were classified as type I, Ic, IIa and IIb. Hypertrophy of the muscle was first observed about ten days after induction of CH. All fibre types appeared to contribute to this hypertrophy. During the period between four and twenty eight days there was a marked increase in the percentage of type I fibres, mainly at the expense of type IIa, as compared with control muscles. During this CH period so called 'intermediate' Ic fibres were found, indicating fibre type transition taking place. The isometric twitch time to peak tension (TPT) of the plantaris muscle was studied in situ. The TPT of CH muscles remained the same during the experimental period of seven weeks. This might be explained by the effect of the increase in type I (slow) fibres being masked by the far larger number of fast fibres, which still accounted for approximately 79% of the total number of fibres after CH.

Aging↗
PubMed1995

[Spiral computerized tomography, multiplane transesophageal echocardiography and magnetic resonance imaging in the diagnosis of thoracic aortic dissection].

The aim of this study was the evaluation of spiral computed tomography (Spiral-CT), multiplane transesophageal echocardiography (multiplane TEE) and magnetic resonance imaging (MRI) in the diagnosis of thoracic aortic dissection. 41 patients were examined: 30 with clinically suspected acute aortic dissection (14 Stanford A, 7 Stanford B), 11 with aortic repair (7/11 with persisting distal dissection). In 14 patients there was involvement of the supraaortic vessels. Sensitivity of Spiral-CT, multiplane TEE and MRI in the detection of aortic dissection was 100%, specificity was 100, 92, and 91%. In the assessment of involvement of aortic arch vessels sensitivity was 100, 67, and 60%, specificity was 100, 95, and 90%. The new imaging modalities Spiral-CT and multiplane TEE are equal to MRI in the detection of aortic dissection. In the assessment of the supraaortic branches Spiral-CT is superior to multiplane TEE and MRI and might become the method of choice.

Adult↗
PubMed1995

Adolescent diabetes management and mismanagement.

OBJECTIVE: To document the existence and prevalence of adolescent-generated diabetes management techniques. RESEARCH DESIGN AND METHODS: One hundred forty-four adolescents completed the confidential questionnaire developed for this study. Glycohemoglobin was also obtained for each individual. RESULTS: Within the 10 days before their clinic visit, many adolescents admitted to engaging in various mismanagement behaviors, with 25% admitting to missing shots. Parents tend to underestimate adolescent mismanagement. Missing shots was significantly related to poor control (P < 0.01). Older adolescents engaged in more mismanagement than their younger cohorts (P < 0.001). The questionnaire factored into two subscales: blatant mismanagement and faking. CONCLUSIONS: This study shows the importance of recognizing the prevalence of mismanagement among adolescents.

Adolescent↗
PubMed1995

[Hearing screening within the scope of pediatric U5 preventive examination: can diagnosis be improved by use of a parent questionnaire?].

OBJECTIVE: Assessment of a) the efficacy of hearing loss screening in baby check-ups at the age of 6 to 8 months b) the efficiency and efficacy using parent questionnaires about hearing loss risk factors and parents' concern about the child's hearing as part of baby check-up. METHODS: The analyses are based on 7282 baby check-ups carried out in 47 pediatricians' offices in the Düsseldorf area from July 1991 to March 1993: 3385 of these check-ups were performed in the traditional manner (period A; July 1, 1991, to January 1, 1992; 3897 check-ups involved parent questionnaires (period B June 1, 1992, to March 31, 1993). All children who failed the tests and a random sample of those who had passed the test when tested in the traditional manner, were offered extensive hearing assessment. RESULTS: In period A, 4.3% of the children failed the test as compared to 21.7% with the first version of the questionnaire and 14.3% with a revised questionnaire in period B. Compliance to the offer of extensive hearing assessment was unsatisfactory (53% in period A and 63% in period B). The first extensive hearing examination failed to distinguish healthy children from children with probable sensorineural hearing loss in about 30% of the patients, mainly because of glue ear. One child with sensorineural hearing loss was identified by the screening in period A as compared to six children in period B. CONCLUSIONS: 1) The systematic use of parent questionnaires in baby check-ups at ages 6 to 8 months is likely to increase the efficacy of the screening. 2) The efficiency of the questionnaires currently in use, however, needs to be improved and can be improved with the data from the study. 3) The compliance with extensive hearing testing in children who have failed the screening test must be improved. 4) Due to the high prevalence of conductive hearing loss in this age group, treatment of potential glue ear problems is mandatory before referral for extensive testing for sensorineural hearing loss.

Deafness↗
PubMed1994

[Cerebral circulation in patients with dilated cardiomyopathy and aortic valve diseases].

The present study was performed in order to investigate the effect of dilated cardiomyopathy and severe aortic valve disease on cerebral blood flow. Cerebral perfusion was determined in 39 healthy volunteers representing two control groups of different age (77.7 +/- 8.7; 79.7 +/- 8.1 ml/100 g/min), in 7 patients with dilated cardiomyopathy (64.0 +/- 4.7 ml/100 g/min), in 11 patients with severe aortic stenosis (71.1 +/- 14.8 ml/100 g/min), and in 6 patients with severe aortic regurgitation (54.6 +/- 5.8 ml/100 g/min). Regional cerebral blood flow was measured with the 133Xenon inhalation method. Cerebral blood flow in severe aortic regurgitation patients (p = 0.006) was markedly and significantly reduced versus controls, whereas in dilated cardiomyopathy patients (p = 0.197) and in patients with severe aortic stenosis (p = 0.111) cerebral blood flow was not significantly reduced. A chronic adaptation of cerebral blood flow to the profound reduction of cardiac output is assumed in dilated cardiomyopathy patients. The collapsing pulse and the maximal reduction of mean arterial blood pressure in severe aortic regurgitation patients cause the reduction of autoregulatory capacity of cerebral blood flow with subsequent decrease of brain perfusion. Measurement of cerebral blood flow appears to be suitable for evaluation of perfusion deficits due to cardiac abnormalities. It provides an additional parameter for estimating the indication of valve replacement in patients with aortic valve disease.

Adult↗
PubMed1993

Demineralized bone powder. Clinical applications for bone defects of the hand.

The results of 20 consecutive cases of bone defects of the hand treated by curettage and implantation of demineralized bone powder compare well with a similarly matched retrospective group managed with autogenous grafts and curettage alone. Results revealed "excellent" (16 patients) or "good" bone healing (4 patients) in the bone powder group on independent radiographic evaluation. Bone bridging was noted at an average of 9.9 weeks. All defects healed without recurrence, resorption or refracture, with follow-up of 4 to 36 months. In the conventionally managed retrospective group there was a 25% failure rate necessitating re-operation. Demineralized bone powder provides a rapid, safe and effective method of management of bone defects of the hand.

Adult↗
PubMed1993

[Effect of frequent ventricular extrasystole on brain circulation in patients with coronary heart disease].

Animal experiments using the microsphere method indicate a 8% reduction of mean cerebral blood flow during parasystolic rhythm induced by ventricular pacing in comparison to a control group with sinus rhythm. The parasystolic rhythm causes changes of systemic arterial blood pressure, which are comparable to the hemodynamic effects of frequent premature ventricular contractions. Because a reduction of cerebral blood flow induced by frequent premature ventricular beats can be assumed by the results of the laboratory investigations, cerebral blood flow was determined in a clinical study in 19 coronary artery disease patients and in 11 healthy, age-adjusted volunteers using the 133Xenon-inhalation method, in order to investigate the effect of ventricular ectopics on cerebral perfusion. Simultaneously Holter monitoring was performed during cerebral blood flow measurements. Cerebral blood flow was estimated by the initial slope index, which is calculated from the early decay of the clearance curve, and by the mean cerebral blood flow index, which is calculated by the stochastic method. Grey matter blood flow is estimated by the two-compartment analysis. Cerebral blood flow in coronary artery disease patients is reduced versus controls. The initial slope indices were 45.2 +/- 5.1 s-1 and 57.4 +/- 7.2(-1), respectively (p < 0.01). In patients with frequent ventricular ectopic activity (739/h) an additional reduction of cerebral blood flow was observed. The initial slope index was 42.6 +/- 6.3 s-1 (p < 0.01). The reduction of cerebral blood flow in coronary artery disease patients is partially due to the coincidence of coronary and cerebral artery disease. Frequent ventricular premature contractions might cause an additional reduction.

Adult↗
PubMed1993

[Effect of a filter system on measurement data and bacterial contamination in lung function studies].

80 measurements of the airway resistance of 20 patients did not yield any significant differences with or without using a bacterial filter (Pall PF 30) (p = 0.1213). Likewise, lung function tests conducted in 61 further patients did not reveal any relevant changes caused by introducing the filter, in respect of the lung function parameters VKin, FEV1, PEF, FEF25, FEF50, FEF75 and TLCO. In these studies the flow receptors were examined for contamination by bacteria. The introduction of the bacterial filter reduced the total count of identified germs from 108, 615 to 307, i.e. by 99.7 per cent, the greatest contamination being found in those parts that were close to the patient (57.6% with filter, 97.1% without filter). Germs of the resident flora of the mouth and pharynx were identified, and occasionally also potential infectious agents such as staphylococcus aureus and streptococcus pneumoniae. The use of a filter system results in a marked decrease in the exposition to germs in lung function tests, without exercising any adverse effect on the measurement data (cross-contamination risk: 0.00078%). This is also achieved--albeit to a lesser extent--by changing those parts of the flow receptor that are close to the patient (cross-contamination risk: 0.0841%). Hence, the use of a filter system appears particularly meaningful in patients with considerable immunodeficiency (advanced stages of HIV infection).

Airway Resistance↗
PubMed1992

Myosin isoforms in hindlimb muscles of normal and dystrophic (ReJ129 dy/dy) mice.

Myosin isoform expression was studied in hindlimb muscles of control (Dy/Dy) and dystrophic (dy/dy) mice of the ReJ129 strain during postnatal development. Three myosin heavy chain isoforms (fast II-B MHC, neonatal MHC, and slow or I MHC) were identified using monoclonal antibodies. Only original fibers, i.e., fibers formed during fetal life, were studied. Necrotic and regenerating fibers were excluded. The disappearance of neonatal MHC was found to be delayed in all muscles of dystrophic mice, except the soleus. The fraction of fibers containing I MHC was similar in control and dystrophic animals at all ages, except during the third postnatal week. The developmental increase in the fraction of fibers expressing II-B MHC was interrupted in dystrophic mice by two marked declines. The first occurred during the second postnatal week at the beginning of the main wave of fiber necrosis, and the second occurred at between 30 and 90 postnatal days.

Animals↗
PubMed1992

Pitfalls in the histochemical demonstration of alpha-glucan phosphorylase activity in glycogen-depleted skeletal muscle fibres.

In the present communication, an investigation is described into the reliability of histochemical methods for the demonstration of alpha-glucan phosphorylase activity in glycogen-depleted skeletal muscle fibres. Human skeletal muscles with glycogen-depleted fibres from patients with diseases of the neuromuscular system and from subjects who had suffered from malignant hyperthermia were used for the study. The location of phosphorylase activity and glycogen was demonstrated with histochemical techniques. Biochemical techniques were used to assay the activity of phosphorylase and the content of glycogen. Biochemical determinations of phosphorylase activity did frequently not reveal significant differences between glycogen-depleted and non-depleted skeletal muscle fibres. In contrast, all histochemical methods investigated, showed little or no phosphorylase activity in the glycogen depleted fibres, indicating that none of the existing histochemical methods revealed reliable staining results in these fibres. Owing to the invalid staining results of the histochemical methods for glycogen-depleted muscle fibres, it is necessary that for metabolic studies a biochemical assay for phosphorylase activity is also to be performed.

Glycogen↗
PubMed1992

Effects of early immobilization on the functional capacity of dystrophic (ReJ 129 dy/dy) mouse leg muscles.

Hindleg muscles of dystrophic (ReJ 129 dy/dy) mice were immobilized during the second post-natal week. Two months after remobilization histopathological features and isometric force characteristics of the m. extensor digitorum longus (EDL) and the m. tibialis anterior (TA) were studied. As a result of early transient immobilization significant differences were observed in muscle morphology and isometric force compared with untreated dystrophic muscles. Restriction of dynamic use of the muscles during this second post-natal week largely prevents the muscles of dystrophic mice from becoming affected by the disease process. Even after two months of remobilization pathology appears to be reduced.

Animals↗
PubMed1991

Lithotripsy of gallstones by means of a quality-switched giant-pulse neodymium:yttrium-aluminum-garnet laser. Basic in vitro studies using a highly flexible fiber system.

The quality-switched neodymium:yttrium-aluminum-garnet laser represents a new instrument for athermal fragmentation of gallstones by transformation of optical energy into mechanical energy in the form of shock waves via local plasma formation. A highly flexible 300-micron fiber transmission system was used in basic investigations to determine the influence of varying pulse repetition rates (5-30 Hz) and pulse energies (15 and 20 mJ) on shock wave intensity and stone fragmentation in vitro for 105 biliary calculi of known size and chemical composition. After performance of 1200 shock wave pressure measurements using polyvinylidenefluoride hydrophones, stone fragmentation was analyzed by determination of fragment removal rates (volume of fragments removed per fragmentation time), ablation rates (mean volume removed per laser pulse), and median fragment sizes for each laser setting. With the quality-switched neodymium:yttrium-aluminum-garnet laser system, all concrements could be reliably disintegrated into small fragments (median diameter, 0.7-1.7 mm). Compared with pure cholesterol stones, a significantly higher fragment removal rate was achieved in cholesterol stones containing 30% calcium phosphate (P = 0.039), in cholesterol stones containing 20% pigment (P = 0.015), and in pure pigment stones (P = 0.007). Fragment removal rates, local shock wave pressures, and median grain sizes were significantly higher at a pulse energy of 20 mJ than with 15 mJ. Shock wave pressures showed a distinct dependence on pulse repetition rates at 20 mJ, yet not at 15 mJ. Because there is no evident hazard of thermal damage to tissue using the quality-switched neodymium:yttrium-aluminum-garnet laser, it appears to be a promising device for nonsurgical biliary stone therapy.

Aluminum↗
PubMed1991

Significance of computed tomography for shock-wave therapy of radiolucent gallbladder stones.

One hundred eleven symptomatic patients (91 women, 20 men) with solitary "radiolucent" stones (proved by a plain radiograph) underwent examination with computed tomography for stone analysis before extracorporeal shock-wave lithotripsy with a second-generation piezoelectric lithoptripter. The aim of the study was to assess the importance of computed tomography as a diagnostic pretreatment procedure compared with the plain abdominal radiograph: computed tomography density values greater than 50 Hounsfield units (HU) were found in 64 of 111 patients with radiolucent stones (58%). Of these 64, 50 patients even had values greater than 90 HU (50/111;45%). The majority of the stones with density values greater than 50 HU had a hyperdense rim (43 of 64) with a mean maximum attenuation of 134 +/- 68 HU. A significantly higher degree of stone disintegration was achieved with stones of group A (less than or equal to 50 HU) than with those in group B (greater than 50 HU and less than or equal to 90 HU) and group C (greater than 90 HU) with respect to the mean maximum fragment size after the first (P less than 0.001) and last (P less than 0.01) lithotripsy and with respect to the total number of shock waves applied (P less than 0.001) and the number of treatments (P less than 0.001). No difference was observed between groups B and C. After all follow-up periods, the rate of complete stone disappearance was higher in group A than in group B (NS for 1, 2, and 4 months of follow-up; P less than 0.01 for month 8; P less than 0.05 for month 12) and group C (P less than 0.05 for 1, 2, and 4 months of follow-up; P less than 0.001 for months 8 and 12). The authors conclude that computed tomographic analysis of gallstones before lithotripsy is more sensitive in detecting nonradiolucent stones than in the plain radiograph. Computed tomographic stone analysis seems to provide a better selection of patients suitable for biliary lithotripsy and could become a standard diagnostic pretreatment procedure to improve stone disintegration and complete stone disappearance after shock-wave lithotripsy and adjuvant chemolitholysis.

Adult↗
PubMed1990

Piezoelectric lithotripsy: stone disintegration and follow-up results in patients with symptomatic gallbladder stones.

One hundred symptomatic patients with radiolucent gallbladder stones were treated with a new piezoelectric lithotripter and oral chemolitholytic agents. Stone disintegration was achieved in 99 of these patients (99%) with a mean (+/- SD) maximum fragment size of 5.1 +/- 4.1 mm. Significant differences were found when the mean (+/- SD) fragment sizes of single stones less than or equal to 20 mm (4.2 +/- 2.5 mm) were compared with those of single stones greater than 20 mm (5.8 +/- 3.4 mm; P less than 0.05) and multiple stones (6.2 +/- 3.8 mm; P less than 0.05), respectively. None of the patients required anesthesia, analgesics, or sedatives before or during the treatment. The stone-free rates for all patients followed up for up to 4-12 months (mean +/- SD, 10.7 +/- 2.9 months) were 18% (1 month), 25% (2 months), 38% (4 months), 52% (8 months), and 67% (12 months). Partly significant differences were obtained in stone-free rates for single stones (less than or equal to 20 mm) compared with larger stones (greater than 20 mm) and multiple stones (P less than 0.05), respectively. Serious adverse reactions (i.e., cholestasis and pancreatitis) were observed in only 3 patients (3%). These conditions were induced by fragment impaction in the common bile duct. In 2 of these patients, endoscopic retrograde cholangiopancreatography with endoscopic sphincterotomy was required. It is concluded that piezoelectrically generated shock waves are suitable for the effective and safe disintegration of gallbladder stones in humans. The anesthesia-free and analgesia-free shock-wave application opens up the possibility to perform biliary lithotripsy as an outpatient procedure. The stone-free rate achieved in combination with oral bile acids is most promising for single stones (less than or equal to 20 mm).

Adult↗
PubMed1990

[Possibilities for early detection of arthroses using imaging procedures].

Today early detection of osteoarthrosis (OA) must imply the recognition of initial changes of articular cartilage before radiological signs appear. A noninvasive imaging technique must meet the demands of imaging the articular cartilage layer with high contrast and surface irregularities (fibrillation) and changes within the substance. This can only be achieved by magnetic resonance imaging (MRI) with optimized conditions (3D-gradient echo sequence). In 80 patients, 62% of them without radiological signs of OA, articular cartilage of the knee joint was prospectively (70 patients) and retrospectively (10 patients) investigated with MRI and compared with the arthroscopic findings. Normal cartilage could be distinguished from pathological conditions with a specificity of more than 90% when evaluating surface morphology, signal homogeneity and, above all, signal intensity (40 patients). Full-thickness defects were identified in all cases. Cartilage fibrillation of differing depths (grades 1-3) could not be differentiated with a sufficient degree of reliability and requires a more subtle evaluation method by means of improved software. Thus, the noninvasive recognition of early pathological changes of articular cartilage in patients without radiological signs of OA has become possible.

Adult↗
PubMed1989

Quantitative analysis of single muscle fibre action potentials recorded at known distances.

In vivo records of single fibre action potentials (SFAPs) have always been obtained at unknown distance from the active muscle fibre. A new experimental method has been developed enabling the derivation of the recording distance in animal experiments. A single fibre is stimulated with an intracellular micropipette electrode. The same electrode is used thereafter for labelling with an auto-fluorescent dye, Lucifer Yellow. In this method there is no use of chemical fixation. The tissue structure is kept as well as possible. In cross-sections the fluorescent fibre is seen and its position is quantitized with respect to the tip of one or more recording wire electrodes. Morphometric data, such as the recording distance and the fibre cross-sectional area, are used for the interpretation of parameters of the SFAPs (peak-peak amplitude, time between the first positive and negative peaks). The present results show that within 300 microns recording distance is not as dominant for the SFAP shape as expected. The method offers also a direct check of the relation between the muscle fibre; diameter and the conduction velocity of the action potential. In the present small set of data there is no simple linear relationship.

Action Potentials↗