Resistance to H-2-restricted but not to allo-H2-specific graft and cytotoxic T lymphocyte responses in lymphoma mutant

The lymphoma mutant RMA-S escaped graft rejection after transplantation over a minor histocompatibility barrier, whereas it was rejected in H-2 allogeneic mice. The parental control line was rejected in both situations. The mutant, which had been selected against MHC class I molecules retained 5 to 10% of the wild-type H-2Db, Kb, and beta 2-microglobulin expression on the cell surface. It remained sensitive to allo-H-2b CTL in vitro, but was completely resistant to minor histocompatibility antigen-specific, H-2b-restricted CTL. It was equally resistant to other H-2b-restricted responses against internally derived Ag, such as tumor-specific CTL or a CTL clone specific for the influenza virus nucleoprotein. The results indicate a target cell defect that selectively abolishes the sensitivity to H-2-restricted CTL directed against internally processed Ag. This appears sufficient to shift the transplantation response over a minor histocompatibility Ag barrier from rejection to acceptance. There are two possible explanations for the results: 1) a block in the MHC class I-directed pathway for internal Ag processing, and 2) subthreshold H-2/Ag ligand density in relation to triggering requirements of restricted CTL. Regardless of the type of defect, the results demonstrate a difference between allo-H-2-specific and H-2-restricted CTL recognition at the level of the target cell.     

Eine neue Bethylidae der GattungLytopsenella Kieffer 1911 aus dem Baltischen Bernstein (Hymenoptera: Chrysidoidea)

Lytopsenella kerneggeri n.sp. from Baltic amber (Upper Eocene) is described and compared with the hitherto known fossil and recent species of the genus. The phylogenetic position ofLytopsenella within the Bethylidae is discussed. PossiblyLytopsenella must be regarded as a paraphyletic grouping as autapomorphic characters of this taxon are unknown. Hence, the clarification of the exact phylogenetic position of the species ofLytopsenella is impossible.     

A review of the Nearctic digger‐wasp genus Microstictia Gillaspy, 1963, with description of two new species from Arizona and Florida (Hymenoptera: Apoidea: Crabronidae)

The genus Microstictia is characterized, its species are diagnosed and keyed; their distribution and collecting period summarized; and their taxonomic status discussed. Photographs of selected important characters are provided. Two new species are described, Microstictia pimensis from Arizona (in the rufescens species group) and M. eos from Florida (in the femorata species group). This is the first unambiguous record of Microstictia from the eastern USA. Based on this finding, M. femorata may actually have originated from Florida, which is frequently questioned. Microstictia minutula (described in Monedula), currently misinterpreted, is a valid name for M. texensis Gillaspy, new synonym. This new synonymy is largely based on female colour characters, whose significance is discussed. The species hitherto known as M. minutula is actually M. exigua (W. Fox), with M. divergens (J. Parker) as a new junior synonym.     

Role of ultrasonography in diagnosing early rheumatoid arthritis and remission of rheumatoid arthritis - a systematic review of the literature

Introduction

Ultrasonography (US) might have an added value to clinical examination in diagnosing early rheumatoid arthritis (RA) and assessing remission of RA. We aimed to clarify the added value of US in RA in these situations performing a systematic review.

Methods

A systematic literature search was performed for RA, US, diagnosis and remission. Methodological quality was assessed; the wide variability in the design of studies prohibited pooling of results.

Results

Six papers on the added value of US diagnosing early RA were found, in which at least bilateral metacarpophalangeal (MCP), wrists and metatarsophalangeal (MTP) joints were scanned. Compared to clinical examination, US was superior with regard to detecting synovitis and predicting progression to persistent arthritis or RA. Eleven papers on assessing remission were identified, in which at least the wrist and the MCP joints of the dominant hand were scanned. Often US detected inflammation in patients clinically in remission, irrespective of the remission criteria used. Power Doppler signs of synovitis predicted X-ray progression and future flare in patients clinically in remission.

Conclusions

US appears to have added value to clinical examination for diagnosing of RA when scanning at least MCP, wrist and MTP joints, and, when evaluating remission of RA, scanning at least wrist and MCP joints of the dominant hand. For both purposes primarily power Doppler US might be used since its results are less equivocal than those of greyscale US.     

Yield Strength of Human Erythrocyte Membranes to Impulsive Stretching

Deformability while remaining viable is an important mechanical property of cells. Red blood cells (RBCs) deform considerably while flowing through small capillaries. The RBC membrane can withstand a finite strain, beyond which it ruptures. The classical yield areal strain of 2–4% for RBCs is generally accepted for a quasi-static strain. It has been noted previously that this threshold strain may be much larger with shorter exposure duration. Here we employ an impulse-like forcing to quantify this yield strain of RBC membranes. In the experiments, RBCs are stretched within tens of microseconds by a strong shear flow generated from a laser-induced cavitation bubble. The deformation of the cells in the strongly confined geometry is captured with a high-speed camera and viability is successively monitored with fluorescence microscopy. We find that the probability of cell survival is strongly dependent on the maximum strain. Above a critical areal strain of ∼40%, permanent membrane damage is observed for 50% of the cells. Interestingly, many of the cells do not rupture immediately and exhibit ghosting, but slowly obtain a round shape before they burst. This observation is explained with structural membrane damage leading to subnanometer-sized pores. The cells finally lyse from the colloidal osmotic pressure imbalance.     

Early and late patterns of stimulus-related activity in auditory cortex of trained animals

 Epidural electrocorticograms over the right auditory cortex (field AI) were measured using implanted 18-channel (3×6) electrode arrays in four animals (Mongolian gerbil) trained to discriminate between a rising and a falling frequency modulated tone (frequency range 2–4 kHz). Using a previously introduced classification procedure, transient patterns of cortical activity suitable to discriminate between the rising and the falling modulation were identified. Early (locked to stimulus onset) and late (emerging at variable times poststimulus) patterns could be differentiated. Deletion of increasing numbers of randomly selected electrodes was used to determine a critical density of recording channels required to capture the discriminative power of the early and late patterns. Statistical analysis of the classification revealed a sigmoid dependence of the discriminative power from the number of remaining electrodes with an inflection point at 12 electrodes. The analysis of the minima of the classification statistic revealed that in the early patterns discriminative information was focal on regions corresponding to the tonotopic representation of the stimuli, whereas in late patterns this information seemed to be distributed nonfocally across larger cortical regions. This analysis supports the previous notion of the coexistence of topographically organized activity states related to the physical stimulus features and nontopographically organized states determined largely by intrinsic factors (Ohl et al. 2001). Received: 25 January 2002 / Accepted: 26 November 2002 / Published online: 11 April 2003 Correspondence to: F. W. Ohl (e-mail: frank.ohl@ifn-magdeburg.de, Tel.: +49-0391-6263322, Fax: +49-0391-6263328) Acknowledgements. Supported by grants from BMBF and Land Sachsen-Anhalt. We thank M. Dobrowolny, E. Müller, and K. Ohl for their skilled technical support in various parts of the work.