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Biomedical subjects

M Richter

Publications and source records attributed to M Richter.

At least 163 records · Page 9Linked to original sources
PubMed1998

[Initial experiences with radionuclide mammography at the Cottbus Carl-Thiem Clinic].

In the diagnosis of breast cancer, noninvasive methods are need in order to detect early stages of this disease. These methods have to have a high specificity in order to discriminate malignant and benign lesions. The scintimammography with 99mTc-MIBI might be such a new method. With this examination the early diagnosis of breast cancer might be improved and may reduce the need for diagnostic biopsies. The aim of our examinations was to get first experiences in comparison with the histological results. The histological results were considered to be the reference method. 25 scintigrafical examinations were evaluated, performed from August 1997 to January 1998. The scintigrafical results were recorded qualitative-visually with a score from 1 to 4. The histological results were received within 1 week after realization of the scintigrafical examination. 22 scintigrafical examinations were evaluated correctly. Of 16 benign lesions 14 were evaluated as true negative and 2 as false positive (fibroadenoma, haematoma). Of the 9 breast carcinomas 8 were evaluated as true positive and 1 false negative (lobular carcinoma in situ). In the case of unselected patients, low numbers of examinations and a diameter of the smallest carcinoma from 1.4 cm a sensitivity of 89% and a specificity of 88% has been observed. Our sensitivity and specificity was in the range of the current international scintimammography-studies. Statements about little breast carcinomas (diameter < 1 cm) are not yet available, because such patients were not examined. The scintimammography is not a screening test. It renders no additional information in the case of clear clinical results and/or clear mammography. Therefore useful indications have to be defined in subsequent scintimammography studies. Possible indications are: palpable breast lesions, which appear normal in mammography, uncertain results in mammography without palpable result and in the follow up of operations of breast cancer without mastectomy. It might be interesting to compare in the future new radiological methods and magnet resonance imaging and positron-emission tomography in the diagnosis of breast cancer with the represented conventional method.

Adult↗
PubMed1998

[Orthodontic-surgical cooperation in the treatment of maxillomandibular deformities].

Orthognathic surgery and adult orthodontic treatment are relatively new areas in the medical field. However, a better understanding of the historical background helps to improve today's teamwork between surgeons and orthodontists. For a (too) long period of time, the two schools have progressed in parallel; surgeons and orthodontists ignoring or criticising one another. The main change which led to the current synergy came out when specialists became aware of the importance to decompensate the alveolo dental level, in order to position correctly the basal bones of either the maxilla or the mandible. This change was not easy, especially for the orthodontists, because they were obliged to worsen the deformity even if just momentarily. During the eighties, a better reciprocal understanding of the technical possibilities in each field allowed to progressively improve cooperation between orthodontists and maxillo-facial surgeons. Consequently, as dialogue became more intense, a real "symbiosis" has arisen, based on mutual respect which did not previously exist, or rarely, about fifteen years ago.

Adult↗
PubMed1998

Retinal vasculature changes in Norrie disease mice.

PURPOSE: To correlate morphologic changes in the retinal vasculature with degenerative changes in the neuronal retina of mice lacking 56 amino acids from the N-terminus of the Norrie disease (ND) gene product. METHODS: Posterior eye segments of ND mice of different age groups were investigated by light and electron microscopy (EM) and scanning EM of vascular corrosion cast preparations. The results were qualitatively and quantitatively compared with those obtained in age-matched littermate control mice and C57B1/6 mice. RESULTS: Quantitative evaluation revealed an increase in the number of blood vessels in the interface of the ganglion cell layer and the nerve fiber layer and a decrease in the inner and outer plexiform layers in ND mice older than 9 days compared with control mice. Vessels were also seen adjacent to the vitreous surface of the inner limiting membrane. Most of these vessels showed fenestrations and occasionally penetrated the inner limiting membrane. Hyaloid vessels were still present in the vitreous. The abnormal vascularization pattern was found in the entire retina and occurred in addition to the previously described alterations of the neuronal retina. CONCLUSIONS: There is a malformation of the retinal vasculature and a persistence of hyaloid vessels in the vitreous of ND mice. It is assumed that the ND gene product is required for normal vascularization of the inner retinal layers and for atrophy of hyaloid vessels.

Animals↗
PubMed1998

[Augmentation techniques: are they out?].

UNLABELLED: Basics of ligament augmentation are reviewed from the literature. As biomechanical in-vitro studies, animal experiments, and clinical studies show different designs and data, the results may be interpreted variably. Theoretically there is a positive effect of augmentation, but no significant improvement of clinical results is evident. The goal of our own prospective study was to check the healing capacity of a repaired and augmented ACL with respect to stability compared to a primary or secondary BTB ligament replacement with and without augmentation. 200 patients were allocated to 4 groups. In group I (G1) acute proximal ruptures were repaired arthroscopically and augmented with PDS II-cord. Patients in G2 received an acute and in G3 a late BTB ligament replacement. Additionally in G4 a late ligament replacement was augmented with a PDS II-cord. The clinical results reveal a comparative stability between G1 and G2, and gradually less stability in G3 and G4. Subjectively, knee function was felt best in G1 and G2 while being worst in G3 and G4. There is no significant difference in the mobility of knees between primary and secondary ligament replacement. An additional augmentation doesn't improve the knee stability. CLINICAL RELEVANCE: There is no positive effect of an augmentation technique of a biologic ligament replacement concerning stability, morbidity, complication rate, and costs. Very marginal freshly ruptured cruciate ligaments may be reinserted successfully by a biodegradable augmentation. Subjective feeling and functional stability may be at least equal to a primary ligament replacement. There are no advantages in knee mobility, when a secondary ligament replacement is performed.

Animals↗
PubMed1998

[Distal femoral fractures].

Techniques of operative treatment of supra- and intercondylar fractures have changed in recent years. These changes refer to reduction techniques and implant selection. Operative approach concepts, which remained unchanged for several decades were critically evaluated and modified to a minimal invasive osteosynthesis [MIO]. This included for intraarticular fractures a trans-articular joint reconstruction and a retrograde plate osteosynthesis (TARPO). This technique result in better operative visualization and management of intraarticular comminution, saver fracture healing and better functional outcome. For extraarticular fractures a minimally invasive percutaneous plate osteosynthesis (MIPPO) via stab incisions only or retrograde intramedullary nailing is available. Beside that new strategies and techniques for the avoidance of axial malalignment, rotational deformities and leg length discrepancies are described, as well as a new plate generation (LISS: less invasive stabilization system), which behaves more like an internal fixator. The complex nature of combined fractures and soft tissue injuries of the distal femur and proximal tibia needs special attention and specific management. Distal femoral and proximal tibial fractures in young patients are usually caused by a high energy trauma. They are complicated by a high rate of systemic and local injuries to cartilage, ligaments and skin. The patients in this group with severe injuries need a detailed treatment algorithm, because the surgeon's individual skill, enthusiasm and wishful thinking frequently led to unsatisfactory results. A decision making scheme is presented specifically addressing timing and treatment modalities.

Equipment Design↗
PubMed1998

[Endovascular infrarenal surgery of abdominal aortic aneurysm in selected patients: 3-years outcome and complication management].

We report a over 3-year single center experience with five different self-expanding or ballon-expandable stent-graft devices used for aneurysm exclusion in the infrarental aorta. All devices appeared to offer a safe, efficacious, and minimally invasive means of excluding the aneurysms from circulation. Key to success is restrictive patient selection due to morphological criteria and improvements in surgical techniques and equipment to reduce the incidence of complications and endoleaks. At the moment, patients who opt for the endovascular method of repair should be aware that the minimally invasive technique carries the disadvantage of a higher failure rate compared to open surgery. Long-term results are required to establish selection criteria, especially for younger patients.

Aged↗
PubMed1997

Systolic and diastolic function in patients with chronic heart failure at rest and during exercise.

In our study we tried to evaluate systolic and diastolic function in patients with chronic heart failure (CHF) by using some echocardiographic parameters and invasively measured pulmonary capillary wedge pressure (PCWP). We studied 19 patients with CHF NYHA II-III at rest, at the end of isometric exercise (handgrip) and during a bicycle stress test. Right heart catheterization and echocardiography were simultaneously performed. We measured exchange of blood gases, end diastolic volume (EDV), end systolic volume (ESV), ejection fraction (EF), peak E velocity, peak A velocity, E/A ratio, deceleration time of E wave (DT), time of mitral regurgitation (MR) and effective filling period of left ventricle (FP). We divided patients according to the median of PCWP at rest into two groups: group A with PCWP< or =11 mmHg (10 pts), group B with PCWP>11 mmHg (9 pts). In group A mean PCWP at rest was 6+/-2 mmHg, during handgrip 12+/-4 mmHg and during bicycle exercise 18+/-6 mmHg. In group B mean values of PCWP were 19+/-6 mmHg, 26+/-11 mmHg and 33+/-5 mmHg, respectively. All values were significantly higher in group B (P<0.01). There was a significant difference in pVO2: in group A 18.8+/-3.5 vs. 14.7+/-3.3 ml/kg per min in group B (P<0.03). No differences between the groups were noticed in EDV, ESV and EF. The E/A ratio in group A was less than 1, in group B greater than 1 with the restrictive pattern. No differences between the groups were observed in MR and FP at rest. During bicycle exercise, MR was significantly longer (284+/-98 vs. 164+/-79 ms; P<0.05) and FP shorter (322+/-99 vs. 421+/-74 ms; P<0.05) in group B than in group A. The functional capacity of patients with CHF is influenced not only by EF and other systolic variables, but also by filling conditions. The duration of effective diastole may be one of the most important of them.

Cardiac Catheterization↗
PubMed1997

Functional characterization of a distinct ryanodine receptor mutation in human malignant hyperthermia-susceptible muscle.

Malignant hyperthermia is an inherited autosomal disorder of skeletal muscle in which certain volatile anesthetics and depolarizing muscle relaxants trigger an abnormally high release of Ca2+ from the intracellular Ca2+ store, the sarcoplasmic reticulum. In about 50% of cases, malignant hyperthermia susceptibility is linked to the gene encoding the skeletal muscle ryanodine receptor/Ca2+ release channel (RYR1). To date, eight point mutations have been identified in human RYR1. Although these mutations are thought to lead to an increased caffeine and halothane sensitivity in the contractile response of skeletal muscle, their functional consequences have not been investigated on the molecular level. In the present study, we provide the first functional characterization of a point mutation located in the central part of RYR1, Gly2434 --> Arg. Using high affinity [3H]ryanodine binding as the experimental approach, we show that this mutation enhances the sensitivity of RYR1 to activating concentrations of Ca2+ and to the exogenous and diagnostically used ligands caffeine and 4-chloro-m-cresol. In parallel, the sensitivity to inhibiting concentrations of Ca2+ and calmodulin was reduced, transferring the mutant Ca2+ release channel into a hyperexcitable state.

Calcium↗
PubMed1997

Influence of heavy metal ions on antibodies and immune complexes investigated by dynamic light scattering and enzyme-linked immunosorbent assay.

The effect of Cd2+, Pb2+, Hg2+ and Cu2+ on the aggregation behaviour of monoclonal rat-IgG1-anti-mouse antibodies (kappa-light chain specific) and their antibody-antigen complexes with monoclonal mouse-IgG1 is reported. Investigations were done using the dynamic light scattering method. Cd2+ ions affected the hydrodynamic properties of the antibodies and the immune complex formation very little. More than 4 Cu2+ ions per antibody molecule led to large insoluble aggregates. Pb2+ ions also interacted with antibodies and immune complexes. Instead of "monomeric' antibodies (Ab) or immune complexes (Ab1Ag1), large soluble aggregates were detectable in the solution. Hg2+ ions induced complex formation with 3-4 antibodies per aggregate. Possible kinds of interaction are discussed. Additionally, we tested the antigen binding activity of metal-treated antibodies in ELISA-tests. The Sandwich ELISA technique was used to investigate the serological activity of the metal-treated antibodies, i.e., the reaction with the specific antigen. For these experiments we used the same monoclonal antibodies, mouse-IgG1 and rat-IgG1-anti-mouse. The influence of the above mentioned heavy metal ions was investigated up to a 10-fold molar excess over the antibody concentration. Even at these "unphysiological' high metal ion concentrations an inhibition of the antibody-antigen binding activity was not detectable.

Antibodies, Monoclonal↗
PubMed1997

Contributions to Physiology of the Antenna-Heart in Periplaneta americana (L.) (Blattodea: Blattidae).

An accessory pulsatile organ of an open circulatory system in insects supplying the antennae with haemolymph was investigated. The rhythm of this so-called antenna-heart is generated by a myogenic automatism and can be neuronally influenced via the nervus cardioantennalis.The action potentials of the muscle fibres show typical pre-depolarization and mostly no overshoot. A specific membrane resistance (R(m)) of about 660Omegacm(-2) was calculated for the fibres. Some electrical coupling between the muscle fibres is presumed for synchronization of any myogenically triggered heart beat which could actually be proved experimentally by current injection in the antenna-heart. However, intercalated disks or gap junctions could not be found. Nevertheless, a good coupling factor (U(2)/U(1)) between all fibres was demonstrated by parallel recordings and can be well described by a conductance model according to fibre topology.

Journal Article↗
PubMed1997

Treatment of mandibular fractures with rigid osteosynthesis: using the AO system.

PURPOSE: This study evaluated the results achieved in the surgical treatment of all mandibular fractures at two university centers using the 2.7 AO mandibular system. PATIENTS AND METHODS: A total of 227 patients presenting with 180 single fractures and 47 with double fractures (274 osteosyntheses) were included in this prospective study. RESULTS: During a mean follow-up of 27.5 months (minimum, 12 months), an overall complication rate of 7% was observed. No infection justified early removal of the osteosynthesis material. CONCLUSIONS: The systematic use of the technique recommended by AO for treating mandibular fractures, performed by thoroughly experienced operators on a compliant population, results in a low rate of complications and an early return to normal function.

Adolescent↗
PubMed1997

A new composite made of polyurethane and glass ceramic in a loaded implant model: a biomechanical and histological analysis.

The biocompatibility and osseous integration of a new composite material made of polyurethane and a calcium silicophosphate ceramic was investigated in a loaded implant model in sheep and compared to that of commercially pure titanium. Six months after implantation, interfacial shear strength was higher between the titanium and bone than between the composite and bone. After 2 years, however, the shear strength was significantly higher in the composite group. Histologically, both implants were surrounded by bone and fibrous tissue and there were no signs of inflammation. Direct contact of bone on the composite surface increased significantly with time, whereas there was no time-dependent increase of bone contact on titanium. It can be concluded that the biocompatibility and osseous integration of the composite was very good in the loaded implant model used. It is therefore suggested that the new composite is a promising biomaterial for orthopaedic implants.

Journal Article↗
PubMed1997

Acutely repaired proximal anterior cruciate ligament ruptures in sheep - by augmentation improved stability and reduction of cartilage damage.

The aim of this study was to evaluate the healing capacity of proximal anterior cruciate ligament (ACL) ruptures following primary repair with and without a bioresorbable augmentation. The ACL was transected at the femoral origin in the right knee joint of 24 sheep. The ACL was repaired in eight sheep (group B) without, and in eight sheep (group C) with a bioresorbable augmentation. Eight sheep without repair served as a control (group A). No immobilization was performed in any group. The sheep were sacrificed 13 weeks post-operatively. Macroscopically, all repaired ACLs were healed. The augmentation device was broken in all cases, but not completely degraded. In group A, none of the transected ACLs had healed. The anterior drawer under a load of 50 N was significantly lower in group C than in group A (p<0.01). No significant difference was seen between groups B and A. The distribution and extent of chondromalacia (CM) in the operated knees depended on the type of operative treatment (p<0.01). Groups A and B showed significantly more CM in the operated knee than in the non-operated knee (each p<0.05). Proximal ACL ruptures can heal in sheep after both non-augmented and augmented ACL repair with free-functional rehabilitation. However, augmented repair leads to significantly better stability of the knee joint compared to transected controls and better limits the development of degenerative changes.

Journal Article↗
PubMed1997

Immediate function of temporomandibular joint after total resection and reconstruction.

Two patients with recurrent parotid gland carcinoma required subtotal petrosectomy and infratemporal fossa type C approach. To achieve en bloc resection, the ascending mandibular ramus and the entire temporomandibular joint, including the adjacent temporal bone, were removed. An original technique for immediate reconstruction of the infratemporal region, including the glenoid fossa and the ramus of the mandible, is described. Rigid fixation, as well as good functional and aesthetic results, was achieved with autologous calvarial bone and full-thickness rib grafts, allowing the patients to mobilize their jaw very rapidly.

Adenocarcinoma↗
PubMed1997

[Role of endoluminal ultrasonography in the treatment of rectal carcinoma].

Endoluminal sonography is an excellent technique in preoperative staging of rectal carcinoma. This minimally invasive technology makes individual planning of therapy possible and is a very good tool in postoperative follow-up and documentation. In comparison with the techniques of CT and MRI it is less expensive and the mobile unit can easily be moved e.g. into the operating theatre. There are no contraindications for this examination, postoperative tissue scars and metal implants will not disturb the imaging. We think that endoluminal sonography will be able to facilitate individual decision making in the treatment of rectal carcinoma.

Endosonography↗
PubMed1997

[Reproductive toxicological fundamental investigations on adult male rats of the WIST/Lppt stock on the determination of swelling after administration of cadmium chloride].

The reproductive-toxic effects after an oral administration of Cadmium as Cadmium chloride on testes and epididymidis of mature Wistar rats were investigated. After daily dosages of 0.3, 0.6, 1.0 oder 2.0 mg CdCl2/kg b.w. over one or two weeks no changes of testes and epididymidis were detected in comparison with control animals by histological observations. By means of morphometrical methods significant changes of the testes from a dosage of 1.0 mg/kg b.w. and changes of the epididymidis previously a dosage of 0.3 mg/kg b.w. have been demonstrated. That means the effect level of Cadmium is higher by consideration of testes than of epididymidis. Consequently, during investigations of reproductive toxicity one hand to test both organs.

Animals↗