Evaluation of two chromogenic agar media for recovery and identification of Staphylococcus aureus small-colony variants

To identify the most rapid and reliable technique for recovery and identification of Staphylococcus aureus small-colony variants (SCVs), the colonial appearance of 106 isolates representing SCVs and the normal phenotype were evaluated on two newly described chromogenic agar media. Although almost all of the SCVs grew on the chromogenic agar media, they did not exhibit a change of color. In comparison with conventional media, S. aureus ID agar (SAID; bioMerieux, La Balme Les Grottes, France) showed the most reliable results, with 49 of 53 SCVs tested growing either as an SCV colony or with a normal phenotype after only 24 h of incubation. Growth of SCVs was often not detected before 72 h of incubation on some of the media tested. In conclusion, the most accurate and rapid method to detect both the species S. aureus and the SCV phenotype is to inoculate specimens onto both Columbia blood agar and SAID.     

The developmentally regulated neural crest-associated glycotope HNK-1 predicts metastasis in cutaneous malignant melanoma

Aberrant glycosylation is a common feature of metastatic sub-clones of malignant tumours and in uveal melanoma in particular, the HNK-1 glycotope has been positively correlated with poor prognosis. So far, no such correlation has been investigated in cutaneous melanoma. In order to do so, HNK-1 expression was evaluated immunohistochemically in 100 primary cutaneous melanomas and correlated with metastasis after up to 10-years' follow-up. Furthermore, HNK-1 expression was analysed in metastatic deposits (19 distant cutaneous metastases and six sentinel lymph node metastases), as well as in benign nevi. Kaplan-Meier analysis revealed a positive association between HNK-1 expression and metastasis (p < 0.005) and multivariate Cox regression analysis adjusted for the standard prognostic markers ulceration and vertical tumour thickness confirmed HNK-1 expression as an independent prognostic marker. HNK-1 expression was preserved in 42% of the distant cutaneous metastases, but metastatic cells in lymph nodes were devoid of HNK-1 immunoreactivity. None of the benign pigmented lesions exhibited HNK-1 immunoreactivity. Expression of the HNK-1 glycotope in cutaneous malignant melanoma is an independent prognostic marker of metastasis. Differential HNK-1 expression at the metastatic sites implies that its expression is modulated by the surrounding environment. As HNK-1 is also transiently expressed during migration of melanocyte precursor cells derived from the neural crest, recapitulation of this transient expression might occur during metastatic spread of cutaneous malignant melanoma.     

Molecular mechanism of temperature sensing by the circadian clock of Neurospora crassa

Expression levels and ratios of the long (l) and short (s) isoforms of the Neurospora circadian clock protein FREQUENCY (FRQ) are crucial for temperature compensation of circadian rhythms. We show that the ratio of l-FRQ versus s-FRQ is regulated by thermosensitive splicing of intron 6 of frq, a process removing the translation initiation site of l-FRQ. Thermosensitivity is due to inefficient recognition of nonconsensus splice sites at elevated temperature. The temperature-dependent accumulation of FRQ relative to bulk protein is controlled at the level of translation. The 5'-UTR of frq RNA contains six upstream open reading frames (uORFs) that are in nonconsensus context for translation initiation. Thermosensitive trapping of scanning ribosomes at the uORFs leads to reduced translation of the main ORF and allows adjustment of FRQ levels according to ambient temperature.     

X-linked mixed deafness (DFN3): cloning and characterization of the critical region allows the identification of novel microdeletions

We have found that the microsatellite marker AFM207zg5 (DXS995)maps to all previously described deletions which are associatedwith X-linked mixed deafness (DFN3) with or without choroideremiaand mental retardation. Employing this marker and pHU16 (DXS26)we have identified two partially overlapping yeast artificialchromosome clones which were used to construct a complete 850kb cosmid contig. Cosmids from this contig have been testedby Southern blot analysis on DNA from 16 unrelated males withX-linked deafness. Two novel microdeletions were detected inpatients which exhibit the characteristic DFN3 phenotype. Bothdeletions are completely contained within one of the known DFN3-deletions,but one of them does not overlap with two previously describeddeletions in patients with contiguous gene syndromes consistingof DFN3, chorolderemia, and mental retardation. Assuming thatonly a single gene is involved, this suggests that the DFN3gene spans a chromosomal region of at least 400 kb.     

Gestörte alpha2-Adrenozeptorfunktion bei Hämodialysepatienten mit renaler Anämie — eine mögliche Ursache der Blutdrucksteigerung unter rekombinantem humanem Erythropoietin?

Summary Nine patients on maintenance hemodialysis and transfusion-demanding renal anemia (group A) were treated with rHuEPO 120 IU/kg i.v. three times per week. Hemoglobin-content was raised from 7.2±0.9 to 10.4±0.8 g/dl. In all patients blood pressure rose, three patients developed arterial hypertension. Mean diastoloic blood pressure was 66±12 and 78±16 mmHg (p<0.001) before and after rHuEPO. Rise in blood pressure was accompanied by a significant fall in plasma-noradrenaline-levels (from 498±100 to 383±75 pg/ml;p<0.05) and alpha₂-adrenoceptor-density (from 574±76 to 384±49;p<0.05). Compared to nine patients on maintenance hemodialysis and hematocrit over 30% (group B), patients with severe renal anemia (group A before treatment) had higher densities of alpha₂-adrenoceptors (574±76 vs. 218±32;p<0.001) despite higher plasma-noradrenaline-levels (498±100 vs. 399±63; n.s.). We suppose a anemia-related disturbance of alpha₂-receptor-function with the result of abolished receptor down-regulation and impaired vascular reagibility to vasoconstricting stimuli. With the correction of anemia receptor-function improves, receptor down-regulation as well as vascular reagibility is re-established resulting in augmented vascular resistance and higher blood pressure.

---

Abkürzungen rHuEPO rekombinantes humanes Erythropoietin - teMAP mittlerer arterieller Blutdruck - RR Blutdrucknach RIVA-ROCCI - RBF regionaler Blutfluß - RPR regionaler peripherer Widerstand     

The role of CD45+CD4+CD3– cells in lymphoid organ development

Summary: In the last 10 years the continuing search for gene function has yielded many mutant mice that unexpectedly showed a complete lack of lymph nodes and/or Peyer's patches. With the realization that all these functionally highly diverse genes are involved at some point in the development of lymphoid organs, the challenge now is to assign a function to the molecules involved in lymphoid organ development. It will be important to determine the sequence of molecular events and assign this to the cellular events that lead to an accumulation of hematopoietic cells in one location, ultimately forming an organized lymphoid organ. Here we will focus on CD45⁺CD4⁺CD3^– cells that are the early colonizing cells in lymph nodes and Peyer's patches and develop a hypothetical model of their contribution to the creation of organized lymphoid structures.     

Classification of anti-FcepsilonRI and anti-IgE autoantibodies in chronic idiopathic urticaria and correlation with disease severity

BACKGROUND: Circulating autoantibodies against FcepsilonRI, IgE, or both occur in approximately one third of patients with chronic idiopathic urticaria (CIU), but not all autoantibodies initiate histamine release. OBJECTIVE: We sought to classify patients with CIU into subsets on the basis of serum bioactivity and immunoreactivity and to examine the relationship between newly defined subtype and disease severity. METHODS: Sera from patients with CIU (n = 78), dermog-raphism (n = 15), and cholinergic urticaria (n = 10) and sera from healthy subjects (n = 39) were analyzed by means of Western blot analysis for anti-FcepsilonRI autoantibodies and for histamine release from basophils and dermal mast cells. In vivo reactivity of autologous serum was tested by means of intradermal injection, and CIU severity was determined on the basis of clinical interview. RESULTS: We classified sera from patients with CIU into 5 subsets: immunoreactive histamine-releasing anti-FcepsilonRI autoantibodies (n = 20 [26%]); immunoreactive anti-FcepsilonRI autoantibodies without histamine-releasing activity (n = 12 [15%]); anti-IgE-like autoantibodies (n = 7 [9%]); serum containing a mast cell-specific histamine-releasing factor (n = 7 [9%]); and sera with no identifiable factor (n = 32 [41%]). Patients with serum histamine-releasing activity had more severe urticaria than patients without such activity. Positive skin test responses to autologous sera were associated with histamine-releasing anti-FcepsilonRI autoantibodies but not with non-histamine-releasing anti-FcepsilonRI autoantibodies. Neither healthy subjects nor patients with dermographism or cholinergic urticaria had his-tamine-releasing anti-FcepsilonRI autoantibodies. CONCLUSION: These data support the specificity of functional anti-FcepsilonRI autoantibodies to CIU. The identification of distinctive subsets of patients suggests that other pathogenic mechanisms occur in CIU in addition to direct ligation of FcepsilonRI by autoantibodies causing dermal mast cell degranulation. Elucidating these mechanisms might lead to new treatments for CIU.     

The effect of erroneous responses on response monitoring in patients with major depressive disorder: a study with event-related potentials

Perceived failure is reported to have detrimental effects on subsequent performance in patients with major depressive disorder. We investigated the error-related negativity (ERN)/error negativity (Ne), an electrophysiological correlate of response monitoring, using a 64-channel EEG. Sixteen patients with DSM-IV major depressive disorder and 16 matched controls participated in an Eriksen flanker task with continuous performance feedback that signaled monetary reward. Compared to controls, patients with major depressive disorder showed a less negative ERN/Ne in error trials following error trials. This result might reflect impaired response monitoring processes in major depressive disorder resulting from an underactivity in a central reward pathway and/or a deficit in strategic reasoning.     

The Topography of Non-Linear Cortical Dynamics at Rest, in Mental Calculation and Moving Shape Perception

Differential cortical activation by cognitive processing was studied using dimensional complexity, a measure derived from nonlinear dynamics that indicates the degrees of freedom (complexity) of a dynamic system. We examined the EEG of 32 healthy subjects at rest, during a visually presented calculation task, and during a moving shape perception task. As a nonlinear measure of connectivity, the mutual dimension of selected electrode pairs was used. The first Lyapunov coefficient was also calculated. Data were tested for non-linearity using a surrogate data method and compared to spectral EEG measures (power, coherence). Surrogate data testing confirmed the presence of nonlinear structure in the data. Cognitive activation led to a highly significant rise in dimensional complexity. While both tasks activated central, parietal and temporal areas, mental arithmetic showed frontal activation and an activity maximum at T3, while the moving shape task led to occipital activation and a right parietal activity maximum. Analysis of mutual dimension showed activation of a bilateral temporal-right frontal network in calculation. The Lyapunov coefficent showed clear topographic variation, but was not significantly changed by mental tasks (p<.09). While dimensional complexity was almost unrelated to power values, nonlinear (mutual dimension) and linear (coherence) measures of connectivity shared up to 37% of variance. Data are interpreted in terms of increased cortical complexity as a result of recruitment of asynchronously active, distributed neuronal assemblies in cognition. The topography of nonlinear dynamics are related to neuropsychological and neuroimaging findings on mental calculation and moving shape perception.