Critical role of the endogenous interferon ligand–receptors in type I and type II interferons response

Separate ligand–receptor paradigms are commonly used for each type of interferon (IFN). However, accumulating evidence suggests that type I and type II IFNs may not be restricted to independent pathways. Using different cell types deficient in IFNAR1, IFNAR2, IFNGR1, IFNGR2 and IFN‐γ, we evaluated the contribution of each element of the IFN system to the activity of type I and type II IFNs. We show that deficiency in IFNAR1 or IFNAR2 is associated with impairment of type II IFN activity. This impairment, presumably resulting from the disruption of the ligand–receptor complex, is obtained in all cell types tested. However, deficiency of IFNGR1, IFNGR2 or IFN‐γ was associated with an impairment of type I IFN activity in spleen cells only, correlating with the constitutive expression of type II IFN (IFN‐γ) observed on those cells. Therefore, in vitro the constitutive expression of both the receptors and the ligands of type I or type II IFN is critical for the enhancement of the IFN activity. Any IFN deficiency can totally or partially impair IFN activity, suggesting the importance of type I and type II IFN interactions. Taken together, our results suggest that type I and type II IFNs may regulate biological activities through distinct as well as common IFN receptor complexes.     

PCR-positivity in harvested bone marrow predicts relapse after transplantation with autologous purged bone marrow in children in second remission of precursor B-cell acute leukaemia

Purging of autologous bone marrow (BM) grafts of children in second remission after a relapse of precursor B acute lymphoblastic leukaemia (ALL) in the BM has been carried out in our laboratory since 1987, initially by complement mediated cell lysis. This protocol was extended by performing an immunorosette depletion before lysis with complement. The aim of the present study was to assess by polymerase chain reaction the presence of residual leukaemic cells in the BM grafts before and after purging. The results were then correlated to clinical outcome. In 24/28 patients a PCR product was obtained by amplification of IgH and/or TcR junctional regions. BM before purging was available for analysis in 13 patients. We found that leukaemic cells could be detected in 8/13 (62%) of these grafts before purging . All these eight patients experienced a relapse, regardless of whether the purging procedure had been successful (defined as achievement of PCR-negativity) or not. In contrast, none of the five patients with PCR-negative grafts before purging relapsed ( P  = 0.0008). One patient died due to transplant-related toxicity. Of the remaining 23 patients, nine patients received a PCR-positive BM graft after purging. All these nine patients experienced a relapse as compared to 6/14 whose BM was PCR-negative after purging ( P  = 0.0072). Two of eight PCR-positive BM grafts could be purged to PCR-negativity. Thus, improvements both in treatment of leukaemia and in purging efficacy are still needed.     

MR shoulder arthrography in patients younger than 40 years of age: Frequency of rotator cuff tear versus labroligamentous pathology

The purpose of this study was to compare the frequency of rotator cuff pathology versus labroligamentous pathology in patients younger than 40 years and to determine whether routine MR arthrography is justified in all patients in this age group, regardless of the clinical symptoms. The MR arthrography was carried out on 332 patients 40 years of age and younger. Two hundred and forty‐three patients had clinical history of instability and possible labroligamentous pathology. Eighty‐nine patients had no history or physical signs of instability and were referred for reasons other than instability, such as assessment for rotator cuff tear. In the 243 patients younger than 40 years with clinical history of potential labral pathology, 39% (95/243) showed a labral tear and 2.1% (5/243) had a full‐thickness rotator cuff tendon tear. In the 89 patients with no history suggesting labral pathology, 19% (17/89) showed an unsuspected labral tear and 4.5% (4/89) had a full‐thickness rotator cuff tear. These findings suggest that, regardless of the clinical indication for referral, patients aged 40 and less referred for shoulder MRI should be imaged using MR arthrography because of the significant risk that symptoms are related to unsuspected labral pathology.     

Glutathione peroxidase inhibits cell death and glial activation following experimental stroke

Stroke is a leading cause of morbidity and mortality in major industrial countries. Many factors contribute to the cellular damage resulting from ischemia-reperfusion (I-R). Growing evidence indicates that reactive oxygen species (ROS) contribute significantly to this process, though their exact mechanism of action is mostly unknown. We have examined the mechanism of protection against I-R injury in transgenic mice that overexpress human glutathione peroxidase (hGPx1), using a focal cerebral I-R model. In this model, transgenic animals show significant reduction of necrotic as well as apoptotic cell death in vulnerable brain regions as demonstrated by TUNEL staining, DNA laddering and ELISA assays. We also observed decreased astrocytic and microglial activation in ischemic brains of animals overexpressing hGPx1. In wild-type mice, neuronal cell death was accompanied with compromise of vascular integrity, edema and neutrophil infiltration, whereas GPx1 mice revealed significant preservation of tissue structure and decreased infiltration of acute inflammatory cells. These results indicate that glutathione peroxidase-sensitive ROS play an important role in regulation of cell death during cerebral I-R as well as in brain inflammatory reactions.     

Developmental lead exposure disturbs expression of synaptic neural cell adhesion molecules in herring gull brains

Neurobehavioral testing of herring gull chicks (Larus argentatus) in both laboratory and field studies indicates that lead exposure during critical periods of development causes neurological deficits that may compromise survival in the wild. Accumulating evidence suggests that lead impairs neurodevelopment, in part, by altering the expression of cell adhesion molecules (CAMs) responsible for the proper formation and maintenance of neural structure and synaptic function. We examined the adhesion molecules NCAM, L1, and N-cadherin in gull brains to determine whether these CAMs are altered by lead exposure and might serve as markers of developmental neurotoxicity. One-day-old chicks were collected from nesting colonies and were laboratory housed. On post-hatching day (PHD) 2, chicks were given 100 mg/kg lead acetate or saline (intraperitoneally). Birds were killed on PHD 34, 44, or 55 (blood-lead levels averaged 27.4, 20.8, and 19.5 microg/dl, respectively). Brains were removed and stored at -70 degrees C until analysis. Expression of CAMs was determined in synaptosomal preparations by Western blotting and the activity of NCAM-associated sialyltransferase (ST) was determined in purified whole brain golgi apparatus. Elevation in synaptosomal polysialylated NCAM expression and a significant increase in golgi ST activity was observed in lead-treated animals at PHD 34. Reductions in synaptosomal N-cadherin were observed at PHD 34 and 44, while L1 expression appeared unaffected by lead at any time-point. By 55 days post-hatching, no differences in N-cadherin expression, polysialylated NCAM expression or NCAM-associated ST activity were seen in lead-treated animals as compared with age-matched control animals. Lead-induced disruption of CAM expression during early neurodevelopment may contribute to behavioral deficits observed in herring gulls in both the laboratory and the field, and may serve as a marker for heavy metal exposure during postnatal development.     

Computer graphics for digitally formatted images

The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use.     

Effects of methyl mercury on the microtubule system of mouse lymphocytes

The effects of in vivo and in vitro methyl mercury (MeHg) treatments on the microtubule system of murine splenic lymphocytes were examined by immunofluorescence microscopy. In vitro exposures to 1 to 10 microM MeHg resulted in time- and concentration-dependent microtubule disassembly. Lymphocytes isolated from mice receiving a single 10 mg/kg injection displayed microtubule damage when examined 2 and 5 days post-treatment. The capacity of in vivo and in vitro treated lymphocytes to respond to the mitogen concanavalin A (Con A) was generally inhibited by MeHg. There was a good correlation between the degree of microtubule disassembly and the inhibition of mitogen responsiveness. In vivo and in vitro treatments that resulted in extensive microtubule damage suppressed the ConA response and blocked lymphocytes early in the stimulation sequence. In vitro MeHg treatment late in mitogenesis caused a rapid, concentration-dependent inhibition of [3H]thymidine incorporation. These results suggest that damage to the microtubule system can serve as an indicator of MeHg toxicity and may underlie the toxicant's effects on lymphocyte functions.