Antigen-antibody complexes in experimental infection with Trichinella spiralis and their role in the development of kidney lesions

The kidneys of rats, experimentally infected with Trichinella spiralis were studied by means of light and fluorescent microscopy. The results obtained suggest that this is a case of a proliferative intra- and extracapillary nephritis. Highest intensity of the pathological process was noted between the 30th and 50th day of the infection. The immunofluorescent reaction of kidney glomeruli demonstrated that the immune complexes were located predominantly in the basal membrane and the mesangium. The serological investigation showed that the maximum level of circulating immune complexes existed between 14th and 21st day after the infection.     

Unilaterale nächtliche Blendempfindung und Photopsien

Ohne ZusammenfassungPräsentiert auf der 102. Tagung der Deutschen Ophthalmologischen Gesellschaft 2004, Berlin 22.–26.09.2004Unterstützt durch ein Stipendium der Fa. Pfizer (TM, PA).     

LED-generated Multifocal ERG On- and Off-responses in Complete Congenital Stationary Night Blindness – A Case Report

We report on the application of a light emitting diode (LED) screen to elicit multifocal ERG on- and off-responses in a patient presenting with the complete type of congenital stationary night blindness (cCSNB): A 63-years old woman was diagnosed with cCSNB by means of standard ERG procedures and dark adaptometry. To confirm this diagnosis and to investigate topographical differences of on- and off-responses a multifocal approach employing long-duration stimuli was added. Results of mfERG-testing were averaged in three groups (a central area of 7.5°, a ring area of 7.5–21.9° and a peripheral ring of 21.9–31.1°). When compared to normal controls (n = 4) on-responses (P1-amplitudes) were severely reduced symmetrically at all eccentricities, while off-responses showed no reduction resulting in an increased off/on-ratio. Furthermore on-latencies of P1 were delayed symmetrically at all eccentricities, whereas off-latencies were normal. To our knowledge this is the first report of multifocal on- and off-responses in a CSNB-patient. Stimulus-generation with a LED-screen provides the advantage of a stable luminance during the long-duration on-phase. Presented in part at the 102^nd meeting of the German Academy of Ophthalmology, Berlin (Germany), 22–26 September 2004.     

The 2-global flash mfERG in glaucoma: attempting to increase sensitivity by reducing the focal flash luminance and changing filter settings

Purpose

To test a new 2-flash multifocal electroretinogram (mfERG) paradigm in glaucoma using a reduced light intensity of the m-frame flash as opposed to the global flash, as it has been suggested that this may increase the responses induced by the global flash, which has been the part of the mfERG response where most changes have been noted in glaucoma.

Methods

A mfERG was recorded from one eye of 22 primary open angle glaucoma (POAG) patients [16 normal tension glaucoma (NTG), 6 high tension glaucoma (HTG)] and 20 control subjects. A binary m-sequence (2^13-1, L _max 100 cd/m², L _min <1 cd/m²), followed by two global flashes (L _max 200 cd/m²) at an interval of 26 ms (VERIS 6.0?, FMSIII), was used. The stimulus array consisted of 103 hexagons. Retinal signals were amplified (gain = 50 K) and bandpass filtered at 1–300 Hz. For each focal response, the root mean square was calculated. We analyzed 5 larger response averages (central 15° and 4 adjoining quadrants) as well as 8 smaller response averages (central 10° and 7 surrounding response averages of approximately 7° radius each). Three epochs were analyzed: the direct component at 15–45 ms (DC) and the following two components induced by the effects of the preceding focal flash on the response to the global flashes at 45–75 ms (IC-1) and at 75–105 ms (IC-2). Statistical analysis was performed using linear mixed effects models adjusted for age.

Results

Responses differed significantly between POAG patients and controls in all central response averages. This difference was larger for the central 10° than for the response average of the central 15°. While these observations held true for all response epochs analyzed, the DC differed least and the IC-1 most when POAG was compared to control. For POAG, the most sensitive differential measure was IC-1 of the central 10° with an area under the ROC curve of 0.78. With a cutoff value of 12.52 nV/deg², 80 % of the POAG patients (100 % HTG, 69 % NTG) were correctly classified as abnormal, while 77 % of the control subjects were correctly classified as normal. When the results of the mfERG were compared to the visual fields, there was a tendency for the mfERG to decrease as the mean defect increased. However, this correlation was only significant in the superior nasal quadrant when the IC-1 of the mfERG was compared to the corresponding area of the visual field.

Conclusion

When compared to findings from previous studies, reducing the luminance of the m-frame flash in the 2-global flash paradigm did not increase the sensitivity and specificity of the mfERG to detect glaucoma further.     

The effect of filtering on the two-global-flash mfERG: identifying the optimal range of frequency for detecting glaucomatous retinal dysfunction

Purpose

To study the effects of filtering bandwidth on the two-global-flash multifocal electroretinogram (mfERG) responses in primary open-angle glaucoma (POAG) compared with control subjects.

Methods

A two-global-flash mfERG (VERIS 6.06?, FMS III) was recorded in 20 healthy subjects and 22 POAG patients with a band-pass filter (BPF) of 1–300 Hz (103 Hexagons, M-sequence stimulus: Lmax 100 cd/m², Lmin < 1 cd/m², global flash: 200 cd/m²). The root-mean-square average of the central 10° was calculated. Three response epochs were analysed: the response to the focal flash, at 15–45 ms (DC), and the following two components induced by the effects of the preceding focal flash on the response to the global flashes at 45–75 ms (IC1) and at 75–105 ms (IC2). The following BPF settings were analysed: 1–300 Hz, 3–300 Hz, 10–300 Hz, 100–300 Hz, 200–300 Hz, 1–10 Hz, 1–100 Hz and 1–200 Hz.

Results

Filtering at 1–300 Hz showed significantly lower responses in POAG than in control subjects (p < 0.001) for all epochs analysed. At 1–100 Hz, this also held true even though the difference between the groups became smaller. At 1–10 Hz, responses were extremely small and did not differ between POAG and control (p > 0.5). This would suggest a filter setting of 10–300 Hz for mfERG recordings in POAG. However, when a filter setting of 10–300 Hz was compared to 1–300 Hz, with a filter setting of 10–300 Hz, the DC in POAG differed more (p < 0.0001) from normal than with 1–300 Hz (p = 0.0002). For IC1 and IC2, the stronger difference between POAG and control was found with 1–300 Hz (p < 0.0001) rather than with 10–300 Hz (p < 0.0001 and p = 0.0005, respectively). For the ‘oscillatory potentials’ at 100–300 Hz, POAG and control differed significantly in IC1 and IC2 (p < 0.05), but not in DC (p = 0.8). However, filtering at 200–300 Hz did not show a difference between POAG and control (p > 0.5). Thus, we applied a filter setting of 1–200 Hz, which seemed to be most sensitive in detecting glaucomatous retinal dysfunction (p < 0.0001).

Conclusions

A filter setting of 1–200 Hz appears most sensitive to detect glaucomatous damage if using a two-global-flash mfERG: using a band-pass filter a with lower low-frequency cut-off, containing the 10 Hz component, may be especially important in the small induced components that show glaucomatous damage most sensitively. High frequencies of 100–300 Hz also contain information that differentiates glaucoma from normal and thus should be included in the analysis.     

Antigen-specific CD4- and CD8-positive signatures in different phases of Mycobacterium tuberculosis infection

Current diagnostic standards for Mycobacterium tuberculosis (MTB) infection do not distinguish between active and latent tuberculosis (TB). To identify specific biomarkers characterizing the different forms of TB infection, we investigated in parallel with the QuantiFERON -TB Gold In-Tube (QFT-IT) the use of flow cytometry measuring CD4 and CD8 MTB-specific immune response in 17 active-TB patients, 21 health care workers (HCW), 14 recent contacts of TB patients (RC-TB), and 10 bacille Calmette Guerin (BCG)–vaccinated healthy controls (BCG-HC).     

Mutations in Streptococcus pneumoniae penicillin-binding protein 2x: importance of the C-terminal penicillin-binding protein and serine/threonine kinase-associated domains for beta-lactam binding

Penicillin-binding protein 2x (PBP2x) mutations that occur during the selection with beta-lactams are located within the central penicillin-binding/transpeptidase (TP) domain, and are believed to mediate resistance by interfering with the formation of a covalent complex of the active site serine with the antibiotic. We now investigated the effect of two point mutations found in two independently obtained laboratory mutants that are located at the surface of the TP domain with their side chains facing outside (G422D respectively R426C). They have no significant effect on resistance to cefotaxime in vivo or on binding to Bocillin?FL to the active site in vitro using purified PBP2x derivatives, thus apparently do not affect the active site directly. In contrast, in silico modeling revealed that they affect van der Waal's interactions with the PASTA1 (PBP and serine/threonine kinase associated) domain of the C-terminal extension and a noncovalent cefuroxime molecule found in the X-ray structure of an acylated PBP2x, suggesting some effect of the mutations on the interaction of the TP domain with PASTA1 and/or with the antibiotic associated with PASTA1. The effect of the PASTA domains on covalent binding of PBP2x to Bocillin FL was then investigated using a series of soluble truncated PBP2x derivatives. Deletion of 127 C-terminal residues, that is, of both PASTA domains, decreased binding dramatically by ～90%. Surprisingly, deletion of only 40 amino acids resulted in the same phenotype, whereas the absence of 30 amino acids affected binding marginally by 10%, documenting a crucial role of the C-terminal domain for beta-lactam binding.