Catecholamine synthesis and metabolism in the central nervous system of mice lacking α2-adrenoceptor subtypes

Background and purpose:

This study investigates the role of α₂-adrenoceptor subtypes, α_2A, α_2B and α_2C, on catecholamine synthesis and catabolism in the central nervous system of mice.

Experimental approach:

Activities of the main catecholamine synthetic and catabolic enzymes were determined in whole brains obtained from α_2A-, α_2B- and α_2C-adrenoceptor knockout (KO) and C56Bl\7 wild-type (WT) mice.

Key results:

Although no significant differences were found in tyrosine hydroxylase activity and expression, brain tissue levels of 3,4-dihydroxyphenylalanine were threefold higher in α_2A- and α_2C-adrenoceptor KO mice. Brain tissue levels of dopamine and noradrenaline were significantly higher in α_2A and α_2CKOs compared with WT [WT: 2.8 ± 0.5, 1.1 ± 0.1; α_2AKO: 6.9 ± 0.7, 1.9 ± 0.1; α_2BKO: 2.3 ± 0.2, 1.0 ± 0.1; α_2CKO: 4.6 ± 0.8, 1.5 ± 0.2 nmol·(g tissue)⁻¹, for dopamine and noradrenaline respectively]. Aromatic L-amino acid decarboxylase activity was significantly higher in α_2A and α_2CKO [WT: 40 ± 1; α_2A: 77 ± 2; α_2B: 40 ± 1; α_2C: 50 ± 1, maximum velocity (V_max) in nmol·(mg protein)⁻¹·h⁻¹], but no significant differences were found in dopamine β-hydroxylase. Of the catabolic enzymes, catechol-O-methyltransferase enzyme activity was significantly higher in all three α₂KO mice [WT: 2.0 ± 0.0; α_2A: 2.4 ± 0.1; α_2B: 2.2 ± 0.0; α_2C: 2.2 ± 0.0 nmol·(mg protein)⁻¹·h⁻¹], but no significant differences were found in monoamine oxidase activity between all α₂KOs and WT mice.

Conclusions and implications:

In mouse brain, deletion of α_2A- or α_2C-adrenoceptors increased cerebral aromatic L-amino acid decarboxylase activity and catecholamine tissue levels. Deletion of any α₂-adrenoceptor subtypes resulted in increased activity of catechol-O-methyltransferase. Higher 3,4-dihydroxyphenylalanine tissue levels in α_2A and α_2CKO mice could be explained by increased 3,4-dihydroxyphenylalanine transport.     

Microglia are more susceptible than macrophages to apoptosis in the central nervous system in experimental autoimmune encephalomyelitis through a mechanism not involving Fas (CD95)

Morphological studies have shown that macrophages and microglia undergo apoptosis in the central nervous system (CNS) in acute experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. To assess the relative levels of macrophage and microglial apoptosis, and the molecular mechanisms involved in this process, we used three-colour flow cytometry to identify CD45lowCD11b/c+ microglial cells and CD45highCD11b/c+ macrophages in the inflammatory cells isolated from the spinal cords of Lewis rats 13 days after immunization with myelin basic protein (MBP) and complete Freund's adjuvant. Simultaneously, we analyzed the DNA content of these cell populations to assess the proportions of cells undergoing apoptosis and in different stages of the cell cycle or examined their expression of three apoptosis- regulating proteins, i.e. Fas (CD95), Fas ligand (FasL) and Bcl-2. Microglia were highly vulnerable to apoptosis and were over-represented in the apoptotic population. Macrophages were less susceptible to apoptosis than microglia and underwent mitosis more frequently than microglia. The different susceptibilities of microglia and macrophages to apoptosis did not appear to be due to variations in Fas, FasL or Bcl- 2 expression, as the proportions of microglia and macrophages expressing these proteins were similar, and were relatively high. Furthermore, in contrast to T cell apoptosis, apoptosis of microglia/macrophages did not occur more frequently in cells expressing Fas or FasL, or less frequently in cells expressing Bcl-2. These results indicate that the apoptosis of microglia and CNS macrophages in EAE is not mediated through the Fas pathway, and that Bcl-2 expression does not protect them from apoptosis. Expression of FasL by macrophages and microglia may contribute to the pathogenesis and immunoregulation of EAE through interactions with Fas+ oligodendrocytes and Fas+ T cells. The high level of microglial apoptosis in EAE indicates that microglial apoptosis may be an important homeostatic mechanism for controlling the number of microglia in the CNS following microglial activation and proliferation.      

Physical functioning is related to both an impaired physical ability and ADL disability: A ten year follow-up study in middle-aged and older persons

ObjectiveIdentification of measures of physical function that mediate or link impaired physical ability with disability in activities of daily living (ADL) is necessary to facilitate the development of interventions to prevent or delay the onset of ADL disability. We examined whether measures of physical function at baseline are determinants of the Short Physical Performance Battery, as measure of physical ability, and disability, at ten years follow-up.Study designProspective cohort study in 625 middle-aged and older persons.Main outcome measuresPhysical ability was measured by Guralniks Short Physical Performance Battery (impaired physical ability: score <6) and ADL ability by the KATZ questionnaire (ADL disability: score ≥1). Physical function was measured by lung function (in men only), handgrip strength, leg strength, and physical activity. The associations between physical function and the dichotomized impaired physical ability and disability-score were estimated using Poisson regression.ResultsBetter lung function and higher leg strength were associated with a lower risk of having impaired physical ability, RR = 0.98, 95% CI [0.96; 0.99] per 10 L/min and RR = 0.97, 95% CI [0.94; 0.99] per 10 Nm, respectively.Higher handgrip strength, leg strength and level of physical activity were associated with a lower risk of having ADL disability, RR = 0.72, 95% CI [0.57; 0.92] per 10 kg, RR = 0.95, 95% CI [0.92; 0.98] per 10 Nm, RR = 0.98, 95% CI [0.96; 0.99] per point-score, respectively.Additional adjustment for baseline ADL disability did not materially changed the point-estimates (except for handgrip strength).ConclusionOverall, leg extensor strength was associated with both an impaired physical ability and ADL disability. Other measures of physical functioning were either related to an impaired physical ability or ADL disability. ADL disability may be an intermediate factor for hand grip strength in the causal chain from impaired physical ability to ADL disability at follow-up. The results of this study show that leg strength might be a relevant parameter to consider for future intervention studies.     

Preclinical anti‐myeloma activity of the novel HDAC‐inhibitor JNJ‐26481585

Pharmacological inhibitors of histone deacetylases (HDACs) are currently being developed and tested as anti‐cancer agents and may be useful to enhance the therapeutic efficiency of established anti‐myeloma treatments. This study preclinically evaluated the effects of the ‘second generation’ pan‐HDAC inhibitor JNJ‐26481585 on human multiple myeloma (MM) cells from established cell lines and primary MM samples (n = 42). Molecular responses in both groups of MM cells included histone acetylation, a shift in Bcl2‐family members towards proapoptotic bias, attenuation of growth and survival pathway activity and Hsp72 induction. Mcl‐1 depletion and Hsp72 induction were the most reliable features observed in JNJ‐26481585‐treated primary MM samples. The drug alone effectively induced myeloma cell death at low nanomolar concentrations. In vitro combination of JNJ‐26481585 with anti‐myeloma therapeutic agents generally resulted In effects close to additivity. In view of the favourable activity of this novel HDAC‐inhibitor towards primary myeloma cells further evaluation in a clinical setting is warranted.     

Clonidine, administered intracerebroventricularly in mice, produces an anti-analgesic effect which may be mediated spinally by dynorphin A (1-17)

Clonidine, administered intracerebroventricularly, was shown to have two actions in the tail-flick test in mice: an overt anti-analgesic and a latent analgesic effect. The anti-analgesic effect was demonstrated by antagonism of the antinociceptive response to morphine, administered intrathecally. This anti-analgesic effect was attenuated by naloxone and nor-binaltorphimine, given intrathecally. Given intracerebroventricularly by itself, clonidine had no antinociceptive effect; however, the administration of naloxone and nor-binaltorphimine intrathecally uncovered the latent antinociceptive action of clonidine given intracerebroventricularly. This sensitivity to the opioid antagonists, given intrathecally, indicated that an endogenous anti-analgesic opioid might mediate the actions of clonidine at the spinal level. The putative opioid was postulated to be dynorphin A (1-17). Analgesia induced by intrathecally administered morphine was attenuated by the intrathecal administration of dynorphin A (1-17) at doses of less than 10 pg (5 fmol). This action of dynorphin was blocked by naloxone (5 fg, 0.014 fmol) and nor-binaltorphimine (10 ng, 12.3 pmol) at doses which did not block mu and kappa receptors in the spinal cord. The authors propose that clonidine, given intracerebroventricularly, activates an anti-analgesic system which descends spinally and is mediated by dynorphin A (1-17) in the spinal cord. This anti-analgesic effect of dynorphin A (1-17) appears to be a new function for dynorphin A (1-17).     

Ultrasound diagnosis of an intraneural ganglion cyst of the peroneal nerve. Case report.

The authors present the case of an intraneural ganglion cyst of the peroneal nerve. The cyst was diagnosed by means of ultrasound, which also gave an exact definition of its size and location, confirmed at operation. Some controversial aspects of these lesions are discussed.     

Prenatal ultrasound diagnosis of the Holt-Oram syndrome

The Holt-Oram syndrome is an autosomal dominant disorder consisting of a congenital heart defect in combination with characteristic upper limb abnormalities. This report presents the ultrasonographic follow-up of two fetuses at risk for the Holt-Oram syndrome. In the first fetus, the existence of Holt-Oram syndrome was suspected at 22 weeks of gestation; a ventricular septal defect, an atrial septal defect, and a minor skeletal defect were found. In the second fetus, no structural abnormalities were discovered until the 30th week, when a small atrial septal defect was detected. In both pregnancies, it was possible to exclude early in gestation the more severe forms of the Holt-Oram syndrome.     

Fitness of drug resistant HIV-1: methodology and clinical implications.

Recent studies of human immunodeficiency virus type 1 (HIV-1) fitness have examined the potential relationship with plasma viral load, drug resistance, and disease progression. For example, treatment of HIV-1 infected individuals with antiretroviral drugs may result in the selection and emergence of inhibitor-resistant variants with reduced replicative capacity. However, it is still unclear whether in vitro HIV-1 fitness has any direct relationship to in vivo disease progression or treatment success. A related question is which in vitro assay of viral fitness is the most appropriate for comparison with in vivo HIV-1 fitness. Characterization of the relative viral fitness of drug-resistant HIV-1 strains may lead to a better understanding of whether or not less fit viruses pose a clinical benefit to the patient.     

Cutaneous lymphomas showing prominent granulomatous component: clinicopathological features in a series of 16 cases

Background  The presence of a prominent granulomatous tissue reaction in skin biopsies from primary cutaneous or systemic malignant lymphomas with secondary cutaneous involvement is a rare but well-known phenomenon.
Objective  This paper aims to characterize and study a series of cutaneous lymphomas showing a prominent granulomatous component.
Patients and methods  The clinical, histopathological and evolutive features of granulomatous variants of mycosis fungoides (5 patients, 2 of them associating 'granulomatous slack skin' features), Sézary syndrome (1 patient), CD30⁺ cutaneous T-cell lymphoma (2 patients), CD4⁺ small/medium pleomorphic cutaneous T-cell lymphoma (1 patient), primary cutaneous B-cell lymphoma (3 patients) and peripheral T-cell lymphoma with secondary epithelioid granulomatous cutaneous involvement (4 patients) were reviewed.
Results  The observed features were clinically non-distinctive. Only those cases presenting with granulomatous slack skin features were clinically suspected (2 patients). Non-necrotizing granulomata (11 patients) and granuloma annulare-like (4 patients) were the most frequently observed histopathological patterns. In five cases, no diagnostic lymphomatous involvement was initially observed. From our series, no definite conclusions regarding prognosis could be established.
Conclusion  The diagnosis of cutaneous lymphoma may be difficult when a prominent cutaneous granulomatous inflammatory infiltrate obscures the true neoplastic nature of the condition. However, the presence of concomitant lymphoid atypia may help to suspect the diagnosis. In doubtful cases, the clinical evolution and the demonstration of a monoclonal lymphoid B- or T-cell population may lead to a definite diagnosis.

Conflicts of interest

None declared.