The role of cell surface proteins in platelet stimulation by monosodium urate crystals

To test whether urate crystal-membrane protein interactions mediate platelet stimulation, platelet membrane proteins were radiolabeled by lactoperoxidase, extracted with 1% Triton X–100, and incubated with urate crystals. The crystal-associated and supernate fractions were isolated and analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and by 2-dimensional isoelectric focusing followed by SDS-PAGE. Four of the lactoperoxidaseradiolabeled polypeptides that associated with urate crystals had reduced molecular weights and pIs of M_r = 105,000, pI 4.9; M_r = 123,000, pI = 4.9; M_r = 123,000, pI = 5.3; and M_r = 132,000, pI = 4.8–6.3, respectively. These proteins were characterized with regard to their labeling intensities, apparent isoelectric points, apparent molecular weights (reduced and nonreduced), lectin-binding properties, carbohydrate- and protein-staining characteristics, and presence or absence in Glanzmann's thrombasthenia. They have been identified as derived from glycoproteins Ib, IIb, and III (Phillips-Agin nomenclature) and an unidentified membrane protein. To test whether removal of these proteins would result in a diminution of platelet response to urate, intact platelets were digested with chymotrypsin, resulting in cleavage of more than 80% of these proteins and a 5-fold reduction in secretory responsiveness to urate crystals. Response to a second platelet stimulus, collagen, was unaffected, indicating an intact secretory mechanism. In addition, when platelets were preincubated with F(ab′)₂ fragments of an antibody directed against these proteins, platelet secretory response to urate was inhibited by 50%, whereas the responses to collagen and thrombin were unaffected. Thus, membrane proteins appear to mediate platelet stimulation by urate crystals.     

Intensive chemotherapy in aggressive lymphomas: updated results of LNH- 80 protocol and prognostic factors affecting response and survival

One hundred patients with aggressive malignant lymphomas treated with the LNH-80 regimen were evaluated for long-term survival and pretreatment characteristics predictive of response and survival. LNH- 80 consists of three intensive courses of adriamycin cyclophosphamide vindesine bleomycin (ACVB) followed by sequential consolidation and final intensification. Eighty-four patients went into complete remission (CR), eight had a partial response (PR), three failed to respond, and five died during induction. Twenty-three patients (27%) relapsed, in two of whom a prolonged second remission was obtained. Sixty-three patients are currently alive, two of them with disease. Four patients died in CR. Median survival and median freedom from relapse survival were not reached with a median follow-up of 4 1/2 years. Characteristics negatively associated with response in multivariate analysis were: poor performance status, bone marrow involvement, and two or more extranodal sites of disease. Duration of CR was associated with splenic involvement. Three characteristics were negatively associated with survival in multivariate analysis: age, high grade subtypes, and bone marrow involvement.     

The skeletal muscle satellite cell response to a single bout of resistance-type exercise is delayed with aging in men

Skeletal muscle satellite cells (SCs) have been shown to be instrumental in the muscle adaptive response to exercise. The present study determines age-related differences in SC content and activation status following a single bout of exercise. Ten young (22 ± 1 years) and 10 elderly (73 ± 1 years) men performed a single bout of resistance-type exercise. Muscle biopsies were collected before and 12, 24, 48, and 72 h after exercise. SC content and activation status were assessed in type I and type II muscle fibers by immunohistochemistry. Myostatin and MyoD protein and messenger RNA (mRNA) expression were determined by Western blotting and rtPCR, respectively. In response to exercise, it took 48 h (young) and 72 h (elderly) for type II muscle fiber SC content to exceed baseline values (P < 0.01). The number of myostatin + SC in type I and II muscle fibers was significantly reduced after 12, 24, and 48 h of post-exercise recovery in both groups (P < 0.01), with a greater reduction observed at 24 and 48 h in the young compared with that in the elderly men (P < 0.01). In conclusion, the increase in type II muscle fiber SC content during post-exercise recovery is delayed with aging and is accompanied by a blunted SC activation response.     

CD200 is a novel p53-target gene involved in apoptosis-associated immune tolerance

During apoptotic cell death, biochemical processes modify self-proteins and create potential autoantigens. To maintain self-tolerance in the face of natural cell turnover, the immune system must prevent or control responses to apoptosis-associated autoantigens or risk autoimmunity. The molecular mechanisms governing this process remain largely unknown. Here, we show that expression of the immunoregulatory protein CD200 increases as murine dendritic cells (DCs) undergo apoptosis. We define CD200 as a p53-target gene and identify both p53- and caspase-dependent pathways that control CD200 expression during apoptosis. CD200 expression on apoptotic DCs diminishes proinflammatory cytokine production in response to self-antigens in vitro and is required for UVB-mediated tolerance to haptenated self-proteins in vivo. Up-regulation of CD200 may represent a novel mechanism, whereby immune reactivity to apoptosis-associated self-antigens is suppressed under steady state conditions.     

Double-Blind Study of Alprazolam, Diazepam, Clonidine, and Placebo in the Alcohol Withdrawal Syndrome: Preliminary Findings

Both a reduction in the inhibitory effects of GABA (disinhibition) and activation of the sympathetic nervous system are manifested during the alcohol withdrawal syndrome. This study was designed to explore the relative efficacy of medications that differentially affects these two biological systems: the benzodiazepines, which attenuate GABAergic disinhibition, and the α₂-adrenergic receptor agonists, which decrease sympathetic activation. The benzodiazepine diazepam ( n = 6), the α₂-receptor agonist clonidine ( n = 7), the benzodiazepine alprazolam (that is also purported to have α₂-receptor agonist properties) ( n = 6), and placebo ( n = 6) were evaluated in their effectiveness in decreasing signs and symptoms of alcohol withdrawal. Drug-free, alcohol-dependent patients were administered 1 of the 4 medications in a double-blind design until symptoms of withdrawal, as measured by the Clinical Instrument Withdrawal Assessment for Alcohol-Revised, were successfully treated. Alprazolam was significantly more efficacious than both clonidine and placebo in decreasing withdrawal symptoms. Diazepam was more effective than clonidine and placebo on some measures of withdrawal. Clonidine decreased systolic blood pressure significantly more than the other two active drugs and placebo, but was no more effective than placebo in decreasing other symptoms of withdrawal. Alprazolam did not significantly decrease blood pressure compared with diazepam or placebo. Despite the small sample size, these preliminary findings suggest that the efficacy of alprazolam in the treatment of alcohol withdrawal is related to its effect at the benzodiazepine receptor and not its α₂-receptor agonist properties.     

T-Cell Membrane CD45RA (2H4) and CD45RO (UCHL1) Determinants: II, Aberrant HLA-ABC Expression by CD45RA and CD45RO Cell Subpopulations of Mature CD4+ T-Cell Leukaemias

Six thymocyte suspensions, 10 normal blood CD4⁺ CD8^- lymphocyte-enriched fractions and leukaemic cells from 24 patients with CD4⁺ mature T-cell lymphoid malignancy (five Sezary Syndrome, six adult T-cell leukaemia-lymphoma and 13 cases of T-cell prolymphocytic leukaemia) were examined in this study for the expression of membrane HLA-ABC by CD45RA (2H4) and CD45RO (UCHL1) subpopulations. These analyses showed that the main increase in HLA-ABC expression by normal CD4⁺ CD8^- blood lymphocytes (mean 490 to 760 FITC units) paralleled the loss of membrane 2H4 whilst the acquisition of UCHL1 was not associated with any significant change in HLA-ABC staining intensity. The sequence of 2H4 differentiation by normal thymocytes, based on the observed increasing levels of HLA-ABC staining intensity appeared to be (a) CD1a ⁺ 2H4^- UCHL1⁺ (25 HLA-ABC fluorescent units), (b)CD1a^-2H4^intUCHL1⁺ (134 units), and (c) CD 1a^- 2H4 ⁺ UCHL1 ^- (197 units). Quantitative estimates of membrane HLA-ABC expression by leukaemic T-cells revealed marked heterogeneity between individual cases irrespective of diagnostic subgroup. Based on the lower observed limits for normal CD4⁺ 2H4⁺ (318 units) and CD4 ⁺ 2H4^- (478 units) fractions, 14% and 38% respectively of the leukaemic 2H4⁺ and 2H4^- components examined showed reduced HLA-ABC expression. Two cases showed very low membrane HLA-ABC levels that were within the range observed for normal CD1a^- thymocytes. In contrast, HLA-ABC staining intensities exceeding that of corresponding normal CD4⁺ 2H4⁺ (710 units) and CD4⁺ 2H4^- (1286 units) subpopulations were seen in a high proportion (65%) of leukaemic 2H4 ⁺ components, with only 14% of 2H4^- fractions showing raised levels and, in two cases, these staining intensities exceeded three times the normal observed limits. In addition to the quantitative differences in HLA-ABC expression, a remarkably consistent (81% of evaluable cases) feature of the leukaemic T-cells was that the 2H4^-UCHL1⁺ subpopulation in CD4⁺ malignancies had a lower HLA-ABC level than the 2H4⁺UCHL1 subpopulation. This was in marked contrast to normal post-thymic T-cells where increasing HLA-ABC expression was seen with increasing UCHL1 (or decreasing 2H4) staining. These results suggest that leukaemic T-cells have an aberrant intra-thymic and post-thymic sequence of 2H4/UCHL1 expression which has become 'uncoupled' from CD1a/HLA-ABC expression.     

Long-Term Therapy With Benzodiazepines Despite Alcohol Dependence Disorder

The author describes the long-term administration of benzodiazepines to seven male patients (58–70 years old), each with at least a 25-year history of alcohol dependence. Benzodiazepines were prescribed for the treatment of an anxiety disorder or sleep disturbance. All seven patients maintained abstinence during benzodiazepine administration, except for a brief period of relapse in two patients. These patients comprised all of the subjects given benzodiazepines for more than 1 week in a Veterans Affairs substance abuse program over a 3-year period. These case reports suggest that the long-term administration of benzodiazepines to carefully selected alcohol-dependent patients is not necessarily incompatible with abstinence. Guidelines for the use of benzodiazepines in this patient population are reviewed.     

Relating Intrinsic Low-Frequency BOLD Cortical Oscillations to Cognition in Schizophrenia

The amplitude of low-frequency fluctuations (ALFF) in the blood oxygenation level-dependent (BOLD) signal during resting-state fMRI reflects the magnitude of local low-frequency BOLD oscillations, rather than interregional connectivity. ALFF is of interest to studies of cognition because fluctuations in spontaneous intrinsic brain activity relate to, and possibly even constrain, task-evoked brain responses in healthy people. Lower ALFF has been reported in schizophrenia, but the cognitive correlates of these reductions remain unknown. Here, we assess relationships between ALFF and attention and working memory in order to establish the functional relevance of intrinsic BOLD oscillatory power alterations with respect to specific cognitive impairments in schizophrenia. As part of the multisite FBIRN study, resting-state fMRI data were collected from schizophrenia subjects (SZ; n=168) and healthy controls (HC; n=166). Voxelwise fractional ALFF (fALFF), a normalized ALFF measure, was regressed on neuropsychological measures of sustained attention and working memory in SZ and HC to identify regions showing either common slopes across groups or slope differences between groups (all findings p<0.01 height, p<0.05 family-wise error cluster corrected). Poorer sustained attention was associated with smaller fALFF in the left superior frontal cortex and bilateral temporoparietal junction in both groups, with additional relationships in bilateral posterior parietal, posterior cingulate, dorsal anterior cingulate (ACC), and right dorsolateral prefrontal cortex (DLPFC) evident only in SZ. Poorer working memory was associated with smaller fALFF in bilateral ACC/mPFC, DLPFC, and posterior parietal cortex in both groups. Our findings indicate that smaller amplitudes of low-frequency BOLD oscillations during rest, measured by fALFF, were significantly associated with poorer cognitive performance, sometimes similarly in both groups and sometimes only in SZ, in regions known to subserve sustained attention and working memory. Taken together, these data suggest that the magnitude of resting-state BOLD oscillations shows promise as a biomarker of cognitive function in health and disease.