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Biomedical subjects

M Vogel

Publications and source records attributed to M Vogel.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Accidental macular injuries caused by the neodymium:YAG laser].

BACKGROUND: The number of laser-users is steadily increasing. This implies an increasing risk of laser accidents with injuries especially of the posterior eye segment. PATIENTS AND METHODS: Two engineers accidentally suffered severe macular injuries caused by Neodym: YAG-lasers with 1064 and 1064/532/355 nm wavelength, respectively. In both cases very high energies were used. One patient looked directly at the laser beam, while in the other case the laser light was reflected from a detector. RESULTS: Depending on the emitted laser energy serious foveal destruction of retinal and chorioideal tissue, surrounding retinal edema and vitreous hemorrhage occurred, resulting in immediate reduction of visual acuity to 0.125 and 1/24 in 1 m, resp., and central scotoma. The most important damage mechanisms are plasma formation and expansion, emission of acoustic transients and cavitation with jet formation. Subsequently, macular scars evolved which were responsible for the limited increase of visual acuity up to 0.32, resp, 0.16 and remaining absolute central scotoma. CONCLUSION: Since there is no effective therapy, attention must be paid to preventive aspects. Improved information and awareness concerning the serious functional consequences of macular injuries is necessary, especially for non-medical users. Due to distinctive technical conditions (experimental arrangement with unprotected laser beam, comparatively high laser energy, prevailing parallel laser radiation), this circle of laser-users has a high risk of accident. A proper opportunity for an improved education are workshops for laser safety precautions.

Accidents, Occupational↗
PubMed1997

Nonspecific binding of IgE to allergens.

Nonspecific IgE binding to allergens was observed in testing myeloma IgEs, namely, IgE-VL and IgE-PS, chimeric IgE (IgE-JW8), and the recombinant IgE Fc epsilon peptide CH1-CH4, in two different immunoassays. This binding was concentration-dependent but detectable only at higher IgE concentration. In RAST inhibition, IgE-allergen interactions could be reduced by using either matching or nonmatching allergens. In order to test whether the nonspecific binding of IgE to allergens was due to carbohydrate interaction, myeloma IgEs and the chimeric IgE were desialized with neuraminidase. Desialized samples were equally well recognized by xenogenic antibodies as native IgEs, but binding of IgE to Fc epsilon receptors on basophils was affected by the treatment, as shown in the histamine-release assay. Desialization of IgE affected also its binding capacity to allergens in RAST: binding of chimeric IgE was reduced, but nonspecific binding of myeloma IgE-VL was enhanced. Hence, nonspecific allergen-IgE binding may be partly due to a lectin-like interaction, but may depend mostly on the tertiary structure of IgE. Thus, nonspecific IgE-allergen interactions might present a problem 1) at high IgE concentration, and 2) depend on the grade of sialization of IgE, which might affect its conformation. This may explain why patients with elevated total IgE levels often have multiple weak positive RASTs with non-cross-reactive allergens.

Allergens↗
PubMed1997

Combined partial trisomy 3p/monosomy 5p resulting in sonographic abnormalities.

We report here a case of partial trisomy of the short arm of chromosome 3 combined with partial monosomy 5p due to malsegregation of a balanced maternal translocation t(3;5). The newborn demonstrated esophageal atresia and complex cerebral malformations. Conspicuous sonographic findings offering the chance of prenatal detection included polyhydramnios without visualization of the stomach, as well as a single umbilical artery. The child died 8 days postpartum.

Abnormalities, Multiple↗
PubMed1997

Comparison of transthoracic three dimensional echocardiography with magnetic resonance imaging in the assessment of right ventricular volume and mass.

OBJECTIVE: Assessment of right ventricular volume and mass with three dimensional echocardiography and comparison with magnetic resonance imaging. METHODS: Measurements of right ventricular volumes performed on three dimensional datasets acquired by transthoracic echocardiography were compared to those obtained from magnetic resonance imaging performed on the same day. Volumes were measured in end systole and end diastole and ejection fraction calculated. Right ventricular mass was assessed in end systole. With both methods, the areas of a 2 mm thick slice of the ventricle were manually outlined and multiplied by the slice thickness to obtain slice volume. Slice volumes were multiplied by the number of measured slices to obtain the ventricular volume. PATIENTS: 16 patients were studied: three with normal hearts, three after surgical repair of coarctation of the aorta, nine following repair of tetralogy of Fallot, and one with Mustard atrial repair of complete transposition of the great arteries. RESULTS: Correlation between end diastolic volumes measured by both methods was r = 0.95 with limits of agreement ranging from -3.5 to 12.5 ml; correlation for end systolic volumes was r = 0.87 with limits of agreement between -4.0 and 16.4 ml; correlation for end systolic right ventricular mass was r = 0.81 with limits of agreement between -7.0 and 20.6 g. Interobserver variability ranged from 4.3% (range 0.2% to 9.3%) for end diastolic volume to 7.6% (1.8% to 15.4%) for mass measurements. CONCLUSIONS: With transthoracic three dimensional echocardiography, end diastolic right ventricular volumes can be assessed with acceptable accuracy in normal hearts and those with enlarged right ventricles, whereas the current method of three dimensional echocardiography is less good for end systolic volumes and not satisfactory for right ventricular mass measurements.

Adolescent↗
PubMed1997

Genomic polymorphism in herpes simplex virus keratitis.

Viruses are the major infectious agents causing conjunctivitis and keratoconjunctivitis. Two antigenic types, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), can be recognized in which numerous genomic variants or genotypes have been described. HSV-1 infection is one of the major causes of blindness. Different strains can induce different types of ocular lesions. Twelve patients with acute herpetic epithelial keratitis were studied by monoclonal antibodies and restriction enzymes, and nine different HSV-1 genomic variants were identified. This study confirms that a variety of HSV-1 strains is associated to this kind of infection.

Herpesvirus 1, Human↗
PubMed1997

[Eye involvement in cancer].

Intraocular metastatic tumors are rare. They are seen in 10% of patients having died of a malignant tumor. Frequently metastatic tumors of the eye are not observed clinically because the may develop in the terminal stage of the disease. The most frequent primary tumor is carcinoma of the breast with 60% of all intraocular metastatic tumors followed bronchogenic carcinoma with 19%. While breast carcinomas usually metastasize years after excision of the primary tumor, bronchogenic carcinomas may metastasize into the eye before the primary tumor reveals itself. Corresponding with its blood supply the choroid, particularly the posterior pole, is the most frequent manifestation of a metastatic tumor of the eye. Here they show the picture of an ill defined, light, slightly prominent, round tumor with irregularities of the overlying retinal pigment epithelium. They are occasionally misinterpreted as amelanotic malignant melanomas of the choroid, nevi, hemangiomas or rhegmatogenous retinal detachment. The prognosis is poor. Once a metastatic tumor has manifested itself within the eye the life expectation is 7-9 months. Orthovolt radiation with a dose of 30 Gy fractioned over 2-3 weeks may be successful. Chemotherapy has not been very satisfactory. We have seen metastatic tumors of the choroid that developed during chemotherapy. Ophthalmologists are not used to the contact with cancer patients. These patients require special care. The relatives should be included in the discussions because they suffer as well and may be very helpful in the further maintenance of the patient. It is recommended to advise the same doctor to care for the patient because this will build up confidence and trust.

Breast Neoplasms↗
PubMed1997

Villous cytotrophoblast proliferating potential in complete and partial hydatidiform mole: diagnostic value of silver-stained nucleolar organizer region (AgNOR)-associated proteins.

Aside from their typical morphologic features, complete (CHM) and partial hydatidiform mole (PHM) are characterized by variable trophoblastic proliferation and/or atypia. CHM and PHM usually present little diagnostic difficulty. However, some may be extremely difficult to distinguish by morphologic features alone. Therefore, we investigated the diagnostic value of silver-stained nucleolar organizer region (AgNOR)-associated proteins in cytotrophblasts as compared to cytogenetic features of nine CHM, nine PHM and six non-molar spontaneous embryonic abortions (controls), as well as of two suspected CHM and two histologically suspected PHM. Tissue sections were submitted to autoclave pretreatment and to silver colloid solution. The proliferating potential of cytotrophoblasts was determined by the analysis of mean number and mean area of AgNORs per nucleus using a PC-based image analysis system. Mean values of AgNOR parameters were significantly different from each other (p < 0.001). Each of the four cases of tentative diagnosis could be assigned to the corresponding group of examined trophoblastic lesions. The evaluation of AgNORs in cytotrophoblasts contributes to a reliable discrimination of CHM and PHM; this fairly simple and economical method could serve as an useful addition to conventional methods of diagnosis in gestational trophoblastic disease.

Cell Division↗
PubMed1997

Intrauterine rhabdomyoma of the heart. A case report.

Primary cardiac tumors are rare findings in adults and children. A case is presented in which ultrasound examination revealed an incredibly large tumor in the heart of a fetus at 24 weeks. Tumor filled the whole left ventricle. Histology and immunohistochemistry were indicative of rhabdomyoma, i.e., a hamartoma that is often associated with tuberous sclerosis.

Actins↗
PubMed1997

[Herpetic keratitis: clinical-virological correlation].

BACKGROUND: Herpetic keratitis is the main infectious cause of corneal opacity. The existence of effective antiviral agents underscores the need of an early diagnosis. AIM: To correlate clinical features of herpetic keratitis with virological studies. PATIENTS AND METHODS: Forty one patients with a clinical diagnosis of herpetic keratitis were studied. Viral isolation, polymerase chain reaction (PCR) and typification were done in a sample taken by swabbing the ocular lesion. RESULTS: Twenty six patients (31% female) had epithelial keratitis, that was mild or moderate in 88% of cases and acute in 77% of them. In 20 patients (77%), viral isolation and PCR were positive (HSV-2 in one case). Fifteen patients (67% female) had stromal keratitis, 93% of cases were moderate or severe and 53% were acute. Viral isolation was negative in all cases and in 20% PCR was positive. CONCLUSIONS: Viral isolation and PCR were equally sensitive in epithelial keratitis, but in stromal keratitis only PCR could detect the virus. Moderate acute dendrite was the predominant clinical manifestation. The higher proportion of women with stromal keratitis supports its possibly autoimmune etiology. HSV-2 is seldomly isolated and possibly associated to vertical transmission.

Acute Disease↗
PubMed1996

Effect of anti-IgE antibodies on Fc epsilonRI-bound IgE.

Anti-IgE mAbs have always been used to trigger mediator release from basophils or mast cells. Now nonanaphylactogenic anti-human IgE Abs are in clinical evaluation as a therapeutic agent against atopic disease. We have found a mAb that is nonanaphylactogenic but recognizes receptor-bound IgE. Interestingly, the Ab prevents the association of IgE with its receptor if immune complexes were formed between IgE and anti-IgE mAb. This explained the phenomenon that addition of anti-IgE Ab to receptor-bound IgE resulted in a decrease of receptor-bound IgE, because IgE dissociating from the receptor was complexed, altering the thermodynamic balance of receptor-bound vs free IgE. Our data show that there are nonanaphylactogenic Abs that do not directly interfere with the receptor binding site on IgE and are capable of preventing the association of IgE with its high affinity receptor. This unique feature would render such an anti-IgE Ab a possible candidate for immunotherapy of atopy.

Anaphylaxis↗
PubMed1996

Architecture and distribution of cancellous bone yield vertebral fracture clues. A histomorphometric analysis of the complete spinal column from 40 autopsy specimens.

The objective of this study was to analyze the structure of cancellous bone and its significance for vertebral fractures. Therefore, the complete spinal column from 40 autopsy cases (18 without diseases affecting the skeleton and 12 osteoporotic) was removed and sectioned in the sagittal plane to a thickness of 1 mm. A surface-stained block grinding technique allowed combined two- and three-dimensional histomorphometric analysis, which included an evaluation of the trabecular bone volume (BV/TV, in %) and the trabecular interconnection (TBPf, in mm). In addition, qualitative investigation of the structure of trabecular bone was done. The distribution of trabecular bone volume within the spinal column of a normal skeleton shows a curve, with the highest values in the cervical spine and a decline in the thoracic and lumbar spine. Osteoporosis presents itself with a pathologically diminished trabecular bone volume, whereas the distribution within the spine is comparable to that of the controls. Osteoporotic patients show an apparently reduced trabecular interconnection. It is important that the measured values for TBPf are not only in general higher, but also more widely dispersed. The age-related decrease of trabecular bone mass is due to the transformation from plates to rods. This is quantitatively indicated by the close correlation of BV/TV and TBPf (P < 0.001, r = 0.85). The bone loss in osteoporosis is a loss of structure and a loss of whole trabeculae, which is caused by perforations. It involves a gradual change from normal bone. However, the polyostic heterogeneity in osteoporosis is immense. These structural differences demonstrate the development of regions of least resistance within the spine, serving as an explanation of osteoporotic fractures. Due to the polyostotic heterogeneity it is impossible to define a threshold mineral content for crash fractures by diagnostic measurements at any reference site.

Adolescent↗
PubMed1996

Left ventricular volume and mass in children on growth hormone therapy compared with untreated children.

The myotropic effects of growth hormone (GH) have long been known. An excess of GH as in acromegaly, causes various problems within the circulatory system including cardiac hypertrophy. Although the latter has not been reported as a complication of GH therapy in children, we assessed this possibility in 54 children. Ninety-six echocardiographic studies were performed, in which bisectional images were analysed by Simpson's rule to determine left ventricular volume and mass. Of special interest were 47 results obtained from girls with Ullrich-Turner-syndrome (UTS) treated with supraphysiological doses of GH. Our results showed a significant increase of the myocardial mass in children on GH therapy compared with untreated children, as well as a dose related effect of GH on cardiac mass in girls and cardiac volume in boys. No cardiac hypertrophy, however, could be observed; the increase in muscular mass merely amounting to a normalization of previously low values.

Adolescent↗
PubMed1996

[Spongiosa structure and polyostotic heterogeneity in osteoporosis. Mechanism of bone transformation, morphology, clinical significance].

Osteoporosis is the most frequent generalized bone disease. The clinical expression of postmenopausal osteoporosis is characterized by spontaneous fractures of the vertebral bodies which affect mainly the trabecular bone structure. Thus the morphological bone transformation in osteoporosis is of clinical relevance. The object of this study was to analyze quantitatively and qualitatively the distribution of three-dimensional structure of cancellous bone in the human spine in osteoporosis. Therefore the complete anterior column of the spine and bone biopsies of the iliac crest of 11 autopsy cases with proven osteoporosis and 26 autopsy cases without primary or secondary bone disease were removed. A 1-mm-thick prepared sagittal section through the center of all vertebral bodies was embedded undecalcified in plastic and stained on the surface using a modification of the von Kossa method. This technique allowed combined two- and three-dimensional measurements simultaneously; these included evaluation of trabecular bone volume, trabecular interconnection, trabecular thickness, and trabecular number. The quantitative spine deformity index and qualitative analysis of the trabecular bone structure completed the investigation. The bone loss in osteoporosis is a loss of structure and the loss of whole trabeculae caused by perforations. The age-related decrease of trabecular bone mass is due to the transformation from plates to rods. Patient with osteoporosis show pathologically diminished trabecular bone volume and apparently reduced trabecular interconnection, while trabecular thickness and trabecular number show age-dependent change. The polyostotic heterogeneity in osteoporosis is immense. Neighboring vertebral bodies show differences of up to 100% in bone volume and bone structure. Due to this fact it is impossible to define a threshold for osteoporotic fractures. At the moment the transformation and loss of trabecular bone structure in osteoporosis is assumed to be irreversible; therefore, early prophylaxis is necessary to prevent clinical manifestations of these changes of bone.

Adolescent↗
PubMed1996

[Targetted ablation of the trabecular meshwork with excimer laser in primary open-angle glaucoma].

The trabecular meshwork and the inner wall of Schlemm's canal constitute 75% of the outflow resistance of the aqueous. Attempts to improve the outflow facility with laser beams have not been satisfactory because they produced thermal effects with coagulation of the trabecular meshwork. With the excimer laser tissue can be removed with minimal thermal effects and necrosis. This results in minimal scar formation. With these qualities the excimer laser lends itself very well for ablation of the trabecular meshwork. It should be possible to create an open connection between the anterior chamber and Schlemm's canal. The goal of our experiments is selected ablation of the trabecular meshwork and the inner wall of Schlemm's canal in order to create pores and enhance the outflow facility. First experiments were carried out on pig and cadaver eyes, followed by eyes destined for enucleation because of malignant melanomas. Finally, we treated 6 patients with open-angle glaucoma. In 4 cases intraocular pressure was reduced by 11 mmHg over a follow-up time of 5 months. In 2 cases IOP rose by 2 mmHg in spite of medication. These preliminary results encourage us to continue with our investigation because there could be a possibility of an effective glaucoma therapy.

Animals↗
PubMed1996

Morphometric analysis of noninvasively assessed bone biopsies: comparison of high-resolution computed tomography and histologic sections.

This article describes a new method to analyze the structural behavior of trabecular bone structure by means of noninvasive measurements of the three-dimensional cancellous bone architecture. For the noninvasive data acquisition, a high-resolution quantitative computed tomography system for peripheral measuring sites (pQCT) was used. With this system and the help of a multiple thin-slice measuring technique, it became possible to examine three-dimensional bone structure with a resolution of 0.25 mm. Using a special three-dimensional segmentation algorithm, mineralized bone was separated from bone marrow and muscle tissue within the three-dimensional stack of CT slices. These segmented data sets can then be processed nondestructively and, even more important, repetitively in either two or three dimensions. In order to validate this noninvasive procedure, a two-dimensional comparative morphometric study was performed including CT slices and corresponding histologic sections prepared after CT measurement. Three representative sections from the three-dimensional stack of CT slices were selected and the morphometric indices of the segmented CT slices were compared with the indices stemming from the corresponding histologic sections prepared after CT measurement. Although the presented approach can only give an example of the method, the results from the morphometric analysis support the assumption that cancellous bone structures based on noninvasive high-resolution CT measurements are representative for trabecular microstructures assessed from histologic bone sections. The study demonstrates the potential of high-resolution CT imaging for in vivo applications of quantitative bone morphometry. This is especially true for repetitive follow-up measurements, which cannot be performed using histologic sections. Additionally, the method offers an easy access to the three-dimensional structure of trabecular bone, which is mandatory for the analyses of the anisotropic mechanical behavior of cancellous bone.

Algorithms↗
PubMed1996

Volume-rendered, three-dimensional echocardiographic determination of the size, shape, and position of atrial septal defects: validation in an in vitro model.

Accurate evaluation of atrial septal defect (ASD) size and shape is very important for the selection of patients for transcatheter occlusion. The ability of volume-rendered, three-dimensional echocardiography (3DE) in displaying ASDs in a dynamic mode has been demonstrated; however, its accuracy in sizing ASDs is unknown. To assess this, we performed 3DE of 10 explanted pig hearts in which ASDs of various locations, sizes, and shapes had been experimentally created. From en face 3DE views of the atrial septum containing the defects, major and minor diameters of the defect were measured by a blinded observer, and these data were compared to direct anatomic measurements. The correlations between 3DE and anatomy for the major and minor ASD diameters were y = 0.83x + 3.4 (r = 0.97, p < 0.0001) and y = 0.92x + 1.3 (r = 0.92, p < 0.0001) respectively. The correlation between the measures for major and minor axis ratio was y = 1.06 x - 0.052, r = 0.91, p < 0.0002. Good agreement between both methods of measurements was demonstrated for all measurements. In addition, 3DE portrayed the location and shape of the defects accurately. Thus 3DE provides excellent visualization of ASD and is able to accurately define the size of the defects. These qualitative and quantitative capabilities enhance the clinical potential of this technique in the appraisal of ASDs for decisions regarding application of closure devices.

Animals↗