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Biomedical subjects

D Hofmann

Publications and source records attributed to D Hofmann.

At least 19 recordsLinked to original sources
PubMed1992

[Effect of form elasticity of the prosthesis shaft in response to stress of the proximal femur].

Uncemented hip prostheses are characterized by a variable design of the stem. In these investigations, nine different prostheses were studied according to the model of a standard bone (Kunststoffnormfemur). After preparation of the cavity of the prostheses with original instruments and after its implantation, strain gauges were placed at 16 certain points. Measurements were carried out in steps of 200 N until reaching the maximal force of 2kN. Prostheses that are characterized by an anatomical design of the stem resemble the physiological nature of normal bone, in contrast to the models with a rectangular cross-section or with a stretched lateral shape of the stem.

Biomechanical Phenomena↗
PubMed1992

[Technical recommendation for connecting osteosynthesis].

In patients with pathological fractures an operative stabilisation is indicated without delay although 40 to 50% of the patients survive only three to four months. Generally palliative operations are practiced. Mostly a connecting osteosynthesis is carried out in which after resection of the tumorous bone the stability can be achieved by the application of plates and filling of the bone defect with cement. In three examplary cases a technical improvement of the impaction of bone cement is described. Using an exactly cutted packing ring of a single use syringe after the application of the plate the bone cement can be filled in easily. By the casting a penetration of the bone cement into the soft tissues can be avoided. An additional effect is that pins of cement extend into the bone narrow with a sufficient support of the filling on the cortical bone. After the removal of the casting the screws can be inserted in the overbridged defect while the polymerisation has nearly finished.

Aged↗
PubMed1992

[Management of multiple traumas: possibilities and limitations in a general hospital].

The chances and the limits in the treatment of patients with multiple trauma are discussed on the example of the Marienkrankenhaus Trier-Ehrang. Definite conditions concerning to the rooms, the staff and the organisation must be realized. Most important is the cooperation between the anaesthesiologist and the surgeon. Short distances, short times and a well trained team are advantageous. If computed tomography and angiography are not available the diagnostical facilities are limited. Severe cranial trauma and spine fractures must be transferred to a special medical centre.

Accidents, Occupational↗
PubMed1992

Investigation of the possibility of solitary waves in the base stacks of DNA.

The possibility of the existence of solitary waves in DNA is investigated. On the basis of our classical model we do not find such a wave in a polynucleotide, but for a stack of adenine molecules without backbone we observe one. Possible extensions of the model for DNA are discussed. From our results we can conclude, that solitons exist in stacked systems without an additional backbone. At least the degree of freedom which couples a nucleotide base (pair) to the sugar-phosphate backbones (N-C stretching vibration) has to be treated with the help of the quantum equations of motion.

DNA↗
PubMed1992

[Effectiveness of Haemophilus influenzae B-diphtheria conjugate vaccination in German children].

BACKGROUND: In 1990 the Haemophilus influenzae b-Diphtheria conjugate vaccine (Hib-D) was introduced in Germany. In addition, most children under 18 months of age failed to develop protective levels of Hib antibodies in response to systemic infections. METHODS: To evaluate the protective efficacy of the Hib-D vaccine in Germany a post marketing case-control study was performed during 1.5. 1990-30.4. 1992. Surveillance for invasive Hib-infections was maintained by pediatricians of 8 hospitals in the Rhein-Main area. The antibody responses to Hib were evaluated by ELISA at the onset (days 0-3) and during remission of disease. RESULTS: During the first year of the study 23 cases per 100,000 children of invasive Hib-infections were recorded. Of these children, 15 suffered from meningitis, 6 from epiglottitis and one from cellulitis and pericarditis respectively. None of these patients had been vaccinated except for one, who received two injections of Hib-D. Due to increased acceptance of the Hib-D vaccine we found a significant reduction of invasive Hib-infections (6 cases per 100,000 children) in the second year of the study. Again, of these children only one child was vaccinated. As expected, in all patients investigated the initial Hib antibody level was below 1 microgram/ml. The development of Hib specific immunity to invasive disease was clearly age dependent: 10 of 11 children below 18 months failed to produce any Hib antibodies (> 0.15 microgram/ml) in response to their infection. In contrast 8 of 10 children older than 18 months developed protective antibody levels to Hib. CONCLUSIONS: The incidence of serious Hib-disease has significantly decreased in Germany since the introduction of the Hib-D vaccine. Because no other Hib vaccine was licensed in Germany our data confirm efficacy and safety of Hib-D reported previously. In addition, children, who contracted disease before 18 months of age, remain susceptible to Hib and require active immunization for protection.

Antibodies, Bacterial↗
PubMed1991

Magnetic resonance imaging as a new diagnostic criterion in paediatric airway obstruction.

Magnetic resonance imaging of the trachea was performed in 21 children with congenital or acquired narrowing of the trachea or main bronchi. Diagnosis included aortic arch anomalies, innominate artery compression, pulmonary artery compression and tracheomalacia. All patients were examined after bronchoscopy. The demonstration of the trachea and the surrounding tissue and vessels on MR images enables the cause of tracheal compression and the degree and location of collapse to be evaluated. MRI is a modality well suited to characterizing tracheal narrowing without employing ionizing radiation or intravenous contrast medium. All MRI examinations were carried out with the patient under general anaesthesia so as not to risk pulmonary deterioration during sedation. In the cases presented MRI is the diagnostic step of choice after tracheobronchoscopy and broadens the diagnostic potential in extrinsic tracheal or bronchial stenosis in paediatric patients.

Airway Obstruction↗
PubMed1991

Indication and results of thoracic surgical procedures in premature infants.

This analysis concerns three groups of malformations: Congenital diaphragmatic hernia, patent ductus arteriosus, and oesophageal atresia. We registered a total mortality rate for all congenital diaphragmatic hernias and defects of 28.5%; the rate in full-term neonates was 27.6% and in premature infants 33.6%. Of 65 infants with a patent ductus arteriosus and a birth weight less than 1500 g, 14 died (21.5%). In most cases death was caused by sepsis. Among the 159 patients with oesophageal atresia who were treated in our hospital, 58 were premature infants. During the last 20 years, the total mortality rate among our patients was 28.9%. We had a mortality rate of 44.8% in premature infants and of 19.8% in full-term neonates. An analysis of the last 10 years showed a survival rate of 97% in healthy infants (group A in Waterston's classification). In group C, the most disadvantageous group (premature infants, severe anomalies), the rate was 61%.

Ductus Arteriosus, Patent↗
PubMed1991

MRI in tracheal stenosis by innominate artery in children.

Pediatric airway obstruction due to anomalies of the course of the innominate artery may produce respiratory distress. MR imaging of the trachea was performed after bronchoscopy on forty-one children with congenital tracheal stenosis. Bronchoscopy only allows the evaluation of the lumen of the trachea, and the degree and location of collapse, and it may be difficult to determine the etiology of the tracheal narrowing. In eighteen out of the forty-one patients MR imaging showed a compression of the trachea by the innominate artery. The MR imaging diagnoses were subsequently compared for accuracy with the diagnoses determined by direct surgical observations. MR imaging of the trachea, the surrounding tissue and vessels allows the evaluation of the cause of tracheal compression and the degree and location of collapse. For evaluation of the cause of airway obstruction. MRI is an ideal method depicting detailed anatomic structure without employing ionizing radiation or intravenous contrast medium.

Brachiocephalic Trunk↗
PubMed1991

[Comparative study of various stabilization procedures in dislocation of the pelvic half joint].

Our experimental studies show that the most rigid methods of osteosynthesis were tested in the groups D, E and F. The operation methods in groups B and C with screw-arthrodeses of the sacro-iliac joint show the greatest load difference, but could not be evaluated statistically. Group A using the tension-wire-banding and group G with our PDS-banding have nearly as good results as the rigid fixation methods. From the biomechanical point of view we find the PDS-banding useful in the treatment of the ruptures of pelvic half-joints. Finally, after using the PDS-technique, the frequently very difficult removal of osteosynthesis material is unnecessary.

Biomechanical Phenomena↗
PubMed1991

Ontogeny of the benzodiazepine receptor in human brain: fluorographic, immunochemical, and reversible binding studies.

The prenatal and postnatal human ontogeny of the central benzodiazepine receptor was investigated in six different brain regions between week 24 postconception and age 14 years. Binding studies, which were performed with [3H]flunitrazepam [( 3H]FNZ), revealed a steep increase in receptor density postnatally in frontal cortex and cerebellum. Bmax values were higher in medulla oblongata, pons, and thalamus than in cortex and cerebellum up to week 26. After that, receptor densities declined significantly in medulla and olive. The same tendency was apparent in pons, whereas receptor density remained unchanged in thalamus. The early ontogeny of the benzodiazepine receptor was also evaluated in fluorographs [( 3H]FNZ) and immunoblots using the alpha 1-subunit-specific monoclonal antibody (mAb) bd-24. Specific radiolabeled proteins with molecular weights of 53K and 59K were visible in cortical membranes from gestational week 8, the earliest time investigated. During further development, the intensity of the 53K band increased without changes in the 59K band. As in other species, postmortem proteolysis in human brain led to a specifically labeled peptide of 47K. The mAb bd-24 immunolabeled only the 53K protein and the 47K peptide.

Adolescent↗
PubMed1991

[Atypical pathogen spectrum in community-acquired infections of the lower respiratory tract in childhood].

Over a period of 14 months, we obtained nasal and throat swabs for virological examinations from patients, admitted to hospital with suspected pneumonia. Fifty-five cases of perihilar bronchitis and 103 cases of pneumonia were diagnosed based on radiological criteria. In 36% (n = 57) of the children, a pathogen could be determined by antigen ELISA. We found the following spectrum: Respiratory syncytial virus: 42%; Influenza A: 8%; Influenza B: 10%; Parainfluenza 1: 3%; Parainfluenza 2: 10%; Parainfluenza 3: 2%; Chlamydia: 17%; and Mycoplasma pneumoniae (serology only): 7%. In a control group of 59 healthy children, only one child showed a pathogen. In the past, viruses and Chlamydia have been underestimated as causes of lower respiratory tract infections. Antigen determination by ELISA has proved to be a reliable and rapid method for their detection.

Adolescent↗
PubMed1991

[Aspects of mucociliary clearance in mucoviscidosis].

Very often the respiratory tract of patients suffering from mucoviscidosis is infested with Pseudomonas aeruginosa which is accused of forming substances that inhibit ciliary motility. It is the aim of the present study to examine the influence of an acute and clinically relevant pseudomonas infestation on the ciliary beat frequency. The ciliary beat rate was determined in 25 mucoviscidosis patients, 13 of them were hospitalised because of acute bronchopulmonary infections. 12 of the patients did not show any clinical signs of an acute respiratory tract infection. In the group of the 13 hospitalised patients, 10 patients (77%) showed infestation of the respiratory tract with Pseudomonas aeruginosa, the mean ciliary beat frequency being markedly reduced at 8.2 +/- 1.7 Hz compared to that of a healthy group with 9.9 +/- 1.0 Hz. The 12 outpatients without clinical signs of acute respiratory tract infections did not show any reduction of the ciliary beat frequency (9.9 +/- 1.4 Hz). Basing on these results, determination of the ciliary beat frequency may possibly develop into an auxiliary criterion to decide on starting a Pseudomonas-active antibiotic therapy.

Adolescent↗
PubMed1991

[Cold air provocation as a methods of differential diagnosis of bronchial asthma and chronic bronchitis].

To assess the usefulness of cold air hyperventilation challenge for the diagnosis of bronchial asthma (B. a.) and chronic bronchitis (c. B.) we studied 25 children with B. a. and 11 children with c. B. between 7 and 14 years. After baseline pulmonary function studies in a whole-body-plethysmograph and spirometry cold air challenge was done by 3 minutes hyperventilation of dry subfreezing (-15 degrees C) air in stepwise increasing doses of 20, 40 and 60% of maximum breathing capacity (MVV). Target size was specific airways resistance (sRaw). Its increase by 100% was considered a positive reaction. Thoracic gas volume (ITGV), airways resistance (Raw) and forced expiratory volume in one second (FEV1) were measured as well. The moment of maximum airway reaction and the time course of the recovery period were also studied. 18 children with B. a. and 1 patient with c. B. reacted significantly with sRaw. We neither found a reaction plateau nor a consistent moment of maximum reaction. Children with B. a. reacted especially with ITGV.

Adolescent↗
PubMed1991

[Ciliary function in bronchopulmonary infections in childhood].

It was the aim of this study to examine the influence of bacterial or viral infections of the airways on the ciliary beat rate in childhood. In 21 children with bacterial bronchopulmonary infections a mean ciliary beat rate of 9.1 +/- 2.4. Hz was found that did not differ significantly from that of the group of the healthy subjects (9.9 +/- 1 Hz). In 7 of the 21 patients we could identify an infection of the respiratory tract with Haemophilus influenzae; in those children there was a marked reduction of the mean ciliary beat rate at 8 Hz. 13 children with viral bronchopulmonary infections had a mean ciliary beat rate of 11.8 +/- 1.8 Hz, which is significantly enhanced when compared with that of the healthy group. Compared with the mean ciliary beat rate of bacterial infections of the respiratory tract there is a significant difference. In viral infections of the airways no value below 9 Hz was found. In case of markedly reduced ciliary beat rate a bacterial infection must be assumed.

Adolescent↗
PubMed1990

Recanalization of chronic, totally occluded coronary arteries by new angioplasty systems.

The benefit and safety of new angioplasty equipment as compared with the conventional guidewire approach was evaluated in 154 consecutive patients. with chronic, totally occluded coronary arteries. The protocol followed a stepwise design: first, conventional guidewires and low-profile balloons were used, followed by "balloon-on-the-wire" systems (Probe, Ace) or by a shaft-enforced, tip-deflecting catheter (Omniflex). In 97 patients with occlusions of 2 to 12 weeks' duration, recanalization was achieved in 51 patients (53%) with the conventional approach and in 29 patients with the new devices (balloon-on-the-wire [n = 5], Omniflex [n = 24]), thereby raising the success rate to 82%. In 57 occlusions of greater than 12 weeks' duration, the recanalization attempt was successful in 58%, mediated in 16 patients (28%) by the Omniflex catheter and in 5 patients by balloon-on-the-wire systems. There were no life-threatening complications and only 1 (0.6%) emergency bypass operation was necessary. New angioplasty devices are therefore of considerable value in the attempt to improve the results of coronary angioplasty in chronic total occlusions.

Angioplasty, Balloon, Coronary↗
PubMed1990

Molecular mass distribution of water-soluble crystallins from the human foetal lens during development.

The water-soluble crystallins of twenty human foetal lenses with gestational ages of 112-231 days were analysed by size-exclusion chromatography. The crystallin distribution showed similar patterns for all foetal lenses, but clear changes in the proportions of different crystallins were evident. The distribution showed that the water-soluble part of all the lenses already contained high-molecular-mass material. Also beta-crystallins of high molecular mass (beta H), formed by post-translational changes, were detected in all stages. During gestation, the percentage of high-molecular-mass crystallins and of alpha-crystallins of low molecular mass (alpha L) decreased significantly. The total beta-crystallins (beta T) and the total gamma-crystallins (gamma T) increased significantly. The low Mr crystallins were resolved into three peaks, designated beta s-, gamma H- and gamma L-crystallins. They increased significantly during development. These significant increases of the low Mr crystallins took place exclusively in the developing lens. The rate of protein synthesis of the low Mr crystallins was 23% of the total water-soluble crystallin synthesis rate.

Chromatography, Gel↗
PubMed1990

Protein profiles of microsections of the fetal and adult human lens during development and ageing.

The water-soluble proteins of the human fetal lens (175- and 285-day-old) contain HM-, pre-alpha-, alpha-, beta- and gamma-crystallins. Using the frozen-sectioning technique, it can be demonstrated that the fetal lens does not have an homogeneous distribution of crystallins, but there are gradual differences between the cortices and the nucleus. The frozen-sectioning technique shows for the adult lens significantly increasing amounts of beta-crystallins of pI 4.95-5.55, especially at the posterior supra-nuclear layer, increasing amounts of HM-crystallins and decreasing amounts of beta-crystallins of pI 5.80-7.05 in the nucleus. This microsectioning technique was correlated with Scheimpflug photographs of the fetal and adult lens. In the fetal lens, the anterior capsule and 2 peaks in the anterior and posterior supranuclear layers could be visualized after densitometry. In the adult lens 5 layers could be demonstrated, e.g. the anterior capsule, the anterior supranuclear layer, the nucleus, the posterior supranuclear layer and the anterior capsule.

Aging↗