Search PubMed⌕ Search

Biomedical subjects

A Haas

Publications and source records attributed to A Haas.

At least 19 recordsLinked to original sources
PubMed2003

[Transpupillary thermotherapy in exudative, age-related macular degeneration].

OBJECTIVE: To assess the effectiveness of a single transpupillary thermotherapy (TTT) in patients with exudative, age-related macular degeneration (AMD). METHODS: In a prospective pilot study, 14 patients with a mean age of 78 years (range: 70-92 years) with subfoveal choroidal neovascularisation (CNV) due to exudative, age-related macular degeneration were treated with a single TTT using a diode laser (810 nm). Seven patients had a classic and seven an occult CNV. Laser beam size was 4.5 mm,the power setting was 800 mW and the exposure lasted 60 s. RESULTS: Twelve out of 14 patients could be followed for a period of 18 months. Stabilisation of the visual acuity was achieved in two patients, ten patients lost three or more Snellen lines. In none of the patients a regression of the CNV could be observed immediately after TTT. Inactive fibrotic scars developed in six patients at the end of the study. CONCLUSION: Our results suggest that TTT, according to our protocol, has no beneficial effect on the spontaneous course of the CNV in patients with AMD.

Aged↗
PubMed2003

Role of factor V Leiden and prothrombin 20210A in patients with retinal artery occlusion.

PURPOSE: Retinal artery occlusion is a common vision-threatening disease. Among other risk factors, coagulopathies leading to a hypercoagulable state have been associated with retinal artery occlusion. Numerous studies have shown that two genetic variants, factor V Leiden and prothrombin 20210A, cause a procoagulant state. However, their role in the pathogenesis of retinal artery occlusion is still unclear. The purpose of the present study was therefore to investigate a possible association between factor V Leiden, prothrombin 20210A, and retinal artery occlusion. METHODS: In the present retrospective case-control study, we studied 136 patients with retinal artery occlusion and 136 age- and gender-matched control subjects. The presence of factor V Leiden and prothrombin 20210A alleles was determined by polymerase chain reaction. RESULTS: The prevalence of heterozygosity for the prothrombin G20210A variant did not significantly differ between patients and controls (three patients vs two controls, P=0.65). Distribution of factor V Leiden genotypes revealed no significant difference among the two groups (heterozygosity: eight patients vs 11 controls, P=0.47). As for other risk factors, arterial hypertension, a history of stroke and myocardial infarction were significantly more frequent in patients than in controls. CONCLUSION: Our data suggest that factor V Leiden and prothrombin 20210A do not play a major role in patients with retinal artery occlusion.

Adult↗
PubMed2001

The evolution of genome size: what can be learned from anuran development?

Differences in nuclear DNA content in vertebrates have been shown to be correlated with cell size, cell division rate, and embryonic developmental rate. We compare seven species of anuran amphibians with a three-fold range of genome sizes. Parameters examined include the number and density of cells in a number of embryonic structures, and the change in cell number in the CNS during development. We show that genome size is correlated with cell proliferation rate and with developmental rate at different stages of embryonic development, but that the correlation between genome size and cell size is only evident at later stages. We discuss the evolution of genome size in amphibians. Our discussion takes into account data that reportedly support two conflicting hypotheses: the "skeletal DNA" hypothesis, which claims a selective role for differences in genome size, and the "junk DNA" hypothesis, which claims that differences in genome size are a random result of the accumulation of noncoding DNA sequences. We show that these supposedly conflicting hypotheses can be integrated into a more complex and inclusive model for the evolution of genome size.

Animals↗
PubMed2001

Role of factor XIII Val34Leu polymorphism in retinal artery occlusion.

BACKGROUND AND PURPOSE: Factor XIII (FXIII) Val34Leu, a common polymorphism in the gene for factor XIII, has been associated with a lower risk of stroke, myocardial infarction, and deep vein thrombosis. Ineffective fibrin cross-linking has been suggested to be causative. The aim of the present case-control study was to investigate the role of FXIII Val34Leu polymorphism in patients with retinal artery occlusion. METHODS: A total of 108 patients with retinal artery occlusion and 313 age- and sex-matched controls were genotyped for the FXIII Val34Leu polymorphism. Factor XIII Val34Leu genotypes were determined by use of allele-specific polymerase chain reaction. RESULTS: Homozygous Leu genotype was found significantly more often in control subjects than in patients with retinal artery occlusion (P=0.018), with an odds ratio of 0.22 (95% confidence interval 0.07 to 0.74). Distribution of the Val/Val and Val/Leu genotypes did not differ significantly between groups. CONCLUSIONS: Because prevalence of homozygous Leu genotype was significantly higher in controls, we conclude that the Leu/Leu genotype is associated with a protective effect against retinal artery occlusion.

Adult↗
PubMed2001

Afipia felis induces uptake by macrophages directly into a nonendocytic compartment.

Afipia felis is a Gram-negative bacterium that causes some cases of human Cat Scratch Disease. A. felis can survive and multiply in several mammalian cell types, including macrophages, but the precise intracellular compartmentalization of A. felis-containing phagosomes is unknown. Here, we demonstrate that, in murine macrophages, most A. felis-containing phagosomes exclude lysosomal tracer loaded into macrophage lysosomes before, as well as endocytic tracer loaded after, establishment of an infection. Established Afipia-containing phagosomes possess neither early endosomal marker proteins [early endosome antigen 1 (EEA1), Rab5, transferrin receptor, trytophane aspartate containing coat protein (TACO)] nor late endosomal or lysosomal proteins [cathepsin D, beta-glucuronidase, vacuolar proton-pumping ATPase, rab7, mannose-6-phosphate receptor, vesicle-associated membrane protein 8, lysosome-associated membrane proteins LAMP-1 and LAMP-2]. Those bacteria that will be found in a nonendosomal compartment enter the macrophage via an EEA1-negative compartment, which remains negative for LAMP-1. The smaller subpopulation of afipiae whose phagosomes will be part of the endocytic system enters into an EEA1-positive compartment, which also subsequently acquires LAMP-1. Killing of Afipia or opsonization with immune antibodies leads to a strong increase in the percentage of A. felis-containing phagosomes that interact with the endocytic system. We conclude that most phagosomes containing A. felis are disconnected from the endosome-lysosome continuum, that their unusual compartmentalization is decided at uptake, and that this compartmentalization requires bacterial viability.

Afipia↗
PubMed2001

Mandibular arch musculature of anuran tadpoles, with comments on homologies of amphibian jaw muscles.

This study analyzes the structure of the mandibular arch musculature in larval, metamorphic, and postmetamorphic anurans of 26 species and makes comparisons with larvae of three caudate and one gymnophione species. Major transformations in early evolution of anuran larvae comprise, for example, the powering of the larval upper jaw cartilages by relocating insertion sites of mandibular arch levators; splitting of some larval muscles into two muscles or muscle heads (m. intermandibularis, m. lev. mand. externus, m. lev. mand. longus); evolution of a muscle invading the lower lip of the oral disk (m. mandibulolabialis), and shift of origin of the internus and longus muscles from dorsal on the cranium to sites on the ventral otic capsule and palatoquadrate, respectively. In all these characters, Ascaphus truei shares the plesiomorphic conditions with caudates. The larva of Xenopus laevis is remarkable because the insertion pattern of three larval mandibular muscles anticipates the postmetamorphic condition of frogs in general and also resembles the caudate condition. Discoglossids, bombinatorids, pelobatids, and neobatrachians are largely similar in their muscle arrangements. The filter-feeding microhylids, however, have most clearly modified the general neobatrachian pattern. Past conflicts in the interpretation and naming of muscles can be attributed to the implicit or explicit homology assumptions used. In particular, the muscles' relations to the branches of the trigeminal nerve have been the dominant criteria for inferring homology and has led to inconsistencies. This concept is questioned herein. It is observed that the relative position of the ramus mandibularis (V(3)) is more variable interspecifically in anuran larvae than previously thought. The relations of the nerve branches and muscles in larvae are maintained during metamorphosis. Considering the muscle pattern to be more conserved in interspecific comparisons than the position of the nerve branches results in a new interpretation of muscle homologies and a hypothesis of jaw muscle evolution in amphibians that is more parsimonious than earlier views. A new, simplified terminology for the jaw musculature is proposed that is applicable for larvae and adults. It maximizes information content and reflects the hypothesized homologies of amphibian jaw muscles.

Anatomy, Comparative↗
PubMed2001

[Multifocal ERG in central areolar choroidal dystrophy].

BACKGROUND: In comparison to full-field ERG a multifocal ERG (mf-ERG) provides functional mapping of the central retina and detection of more localised defects. Central areolar choroidal dystrophy is an autosomal dominant inherited disorder with central atrophy of the choriocapillaries, the retinal pigment epithelium (RPE) and the photoreceptors. Full-field ERG often shows only slight to moderate reductions. The purpose of our study was to investigate the electroretinographic activity of the posterior pole with the mf-ERG in comparison to the photopic full-field ERG in these patients. PATIENTS AND METHODS: We performed a mf-ERG and a photopic full-field ERG in 4 patients with central areolar choroidal dystrophy and in 20 age-matched volunteers who constituted the normal control group. RESULTS: In all patients reductions in b-wave amplitudes of the first order kernel of the mf-ERG in both eyes were evident. Full-field ERG showed decreased b-wave amplitudes in only three eyes. Subnormal amplitudes were found in two eyes and normal amplitudes in three eyes. Additionally ophthalmoscopic lesions were found to a lesser extent than by the mf-ERG. DISCUSSION: The mf-ERG is a valuable tool in detecting central areolar choroidal dystrophy and might be useful in early detection and follow-up, when ophthalmoscopy and full-field ERG are still normal. Moreover it could contribute to differential diagnosis of other retinal diseases of the posterior pole.

Aged↗
PubMed2001

Influence of refractive correction on peripheral visual field in static perimetry.

PURPOSE: To determine the influence of refractive errors on peripheral visual field thresholds in automated static perimetry. METHODS: In 47 subjects (age 16-49 years), the difference of perimetric thresholds was tested in the peripheral visual field without and with contact lens correction, using a custom-made program (Goldmann stimulus size III) with the automated perimeter Octopus 2000 R. Refractive errors ranged from -16.75 to +12.5 diopters. Sixty-four test locations on three concentric rings between 30 degrees and 50 degrees in 19 hyperopic and 28 myopic eyes were tested. RESULTS: All rings in myopic eyes revealed a significant influence of refraction on the differential light sensitivity in the peripheral visual field. In hyperopic eyes only the inner ring showed a significant influence of refraction. The decrease in sensitivity, measured in dB/diopter, for the myopic inner ring was 0.75; for the myopic middle ring it was 0.46; for the myopic outer ring it was 0.22; and for the hyperopic inner ring it was 0.40. CONCLUSIONS: A significant association between refractive errors and differential light sensitivity exists in the peripheral visual field of myopic eyes. Therefore, contact lens wear is recommended when performing automated perimetry of the peripheral visual field of myopic patients with higher refractive errors.

Adolescent↗
PubMed2001

Use of recombinant mitogillin for improved serodiagnosis of Aspergillus fumigatus-associated diseases.

During human infection, Aspergillus fumigatus secretes a 18-kDa protein that can be detected as an immunodominant antigen in the urine of infected patients. Recently, this protein was shown to be mitogillin, a ribotoxin that cleaves a single phosphodiester bond of the 29S rRNA of eukaryotic ribosomes. We proved the immunogenic capacity of mitogillin in a rabbit animal model, indicating its usefulness as an antigen for serological diagnosis of invasive aspergillosis. The mitogillin gene from A. fumigatus was transferred from plasmid pMIT+ to expression vector pQE30 and expressed in Escherichia coli as a fusion protein. Purified recombinant mitogillin was recognized by serum immunoglobulin G (IgG) of polyclonal rabbit sera that were obtained by immunization with purified native mitogillin. Consequently, we developed an enzyme-linked immunosorbent assay for detection of IgG, IgM, and IgA antibodies to recombinant mitogillin. In serum samples of patients suffering from aspergilloma (AO; n = 32), invasive pulmonary aspergillosis (IPA; n = 42), or invasive disseminated aspergillosis (IDA; n = 40), a good correlation of production of IgG antibody against mitogillin and clinical disease was observed (for patients with AO, 100% [32 of 32] were positive; for patients with IPA, 64% [31 of 42] were positive; for patients with IDA, 60% [24 of 40] were positive). In contrast, positive titers for serum IgG and IgM antibodies against mitogillin were found in only 1.3% of the serum samples of healthy volunteers and positive titers for IgA antibody were found in only 1.0% of the serum samples of healthy volunteers (n = 307; specificity = 95.4%). These results indicate that recombinant mitogillin expressed in E. coli can be used for improvement of the serodiagnosis of A. fumigatus-associated diseases.

Adolescent↗
PubMed2001

Hyperhomocyst(e)inaemia, but not MTHFR C677T mutation, as a risk factor for non-arteritic ischaemic optic neuropathy.

BACKGROUND/AIMS: Hyperhomocyst(e)inaemia has been identified as a strong risk factor for stroke, myocardial infarction, and deep vein thrombosis. A point mutation of methylene tetrahydrofolate reductase (MTHFR C677T) has been associated with increased plasma homocyst(e)ine levels. To investigate whether hyperhomocyst(e)inaemia and/or MTHFR C677T mutation are associated with non-arteritic ischaemic optic neuropathy (NAION), a case-control study including 59 consecutive patients with NAION and 59 controls matched for age and sex was performed. METHODS: Fasting plasma homocyst(e)ine levels, MTHFR C677T genotypes, and plasma levels of folate and vitamin B-12 were determined. RESULTS: Mean plasma homocyst(e)ine levels were significantly higher in patients than in controls (11.8 (SD 5.7) micromol/l v 9.8 (2.5) micromol/l, p = 0.02). The odds ratio for patients with homocyst(e)ine levels exceeding the 95th percentile of control homocyst(e)ine levels was 5.8 (95% CI 1.5-21.4). Mean plasma folate levels were significantly lower in patients than in controls (4.3 (1.7) ng/ml v 5.5 (1.9) ng/ml, p = 0.001), whereas plasma vitamin B-12 levels did not differ significantly. Prevalence of the MTHFR C677T mutation was not significantly increased in patients with NAION compared with controls. CONCLUSION: These results suggest that hyperhomocyst(e)inaemia, but not MTHFR C677T mutation is associated with NAION. Determination of plasma homocyst(e)ine levels might be of diagnostic value in patients with NAION.

Aged↗
PubMed2001

Three-dimensional reconstruction of the anal striated musculature in a human fetus.

Conflicting opinions in the recent literature indicate that the morphological organization and function of the anorectal continence organ has, up to now, not been clearly understood. But a clear imagination of the spatial arrangements of this compound muscle system is of clinical relevance for the pediatric surgeon performing reconstructive surgery. We analyzed 18-microm sections of the pelvic region of 4 human fetuses in order to describe the individual components of this muscle complex. A series of 630 Azan-stained sections was the base for the computer-assisted 3D reconstruction of the levator ani and the external sphincter complex in a male human fetus (14th week p.c.). In this context, special attention was paid to the intermediate muscle layer of the puborectalis which develops ventrally from the funnel-shaped levator ani and joins the tripartite ring system of the sphincter muscle dorsally. Our findings lead to a clear imagination of the spatial arrangement of this intermediate layer and characterize the anorectal muscle complex as an integrated ensemble in which the puborectalis holds a key position.

Anal Canal↗
PubMed2001

Development of an experimental paradigm in which to examine human learning using two computer-based formats.

Computer-based self-instructional programs are frequently promoted as means to augment or replace the traditional anatomy curricula taught in medical schools. These programs may range from static slide shows to fully immersive virtual environments. However, the impact of these learning technologies on knowledge acquisition, and their comparative cost/benefit to education remain unclear. As a consequence, we are embarking on a series of experiments to compare knowledge acquisition and the meaningful use of information among students who are learning anatomy using one of two different computer-based self-instructional formats. These studies will be based on a specially developed learning module on basic lung anatomy; they will utilize a variety of assessment tools to measure factual knowledge, conceptual understanding of spatial-anatomic relationships, and the ability to apply newly acquired knowledge of anatomy to clinical problem-solving scenarios. The primary object of this paper is to describe the design and development of the underlying test module and to outline the two computer-based formats that will be evaluated. The virtual reality (VR) environment, UCSD's Anatomic VisualizeR, provides dynamic access to 3-dimensional polygonal models of the lesson content and supports student-centered exploration and learning. The multimedia environment, Microsoft PowerPoint, provides a structured presentation of the lesson content and illustrates important anatomic structures through the use of 2-dimensional images derived by screen captures of models available in the VR learning module. This paper also provides an overview of the first experiment in the series, a pilot study using first-year medical students without previous participation in a medical school anatomy curriculum. For this study, students will be prospectively randomized into two groups, each group learning the lung anatomy lesson using one of the computer-based formats described. Immediate knowledge retention will be measured by asking students to complete the assessment instrument immediately after completing their learning module. The results of the pilot study will be used to refine and improve the design of the remainder of studies planned in this experimental series.

Anatomy↗