Jakob Paues

Expression of melanocortin-4 receptor by rat parabrachial neurons responsive to immune and aversive stimuli.

The pontine parabrachial nucleus is a major relay area for visceral and other interoceptive information, and has been implicated in mechanisms underlying anorexia and food aversion during disease. Thus, physiological studies have shown that peripheral immune stimuli, as well as the administration of aversive substances such as lithium chloride, evoke a prominent Fos-expression in the lateral parabrachial nucleus and behavioral experiments have demonstrated that this structure is critical for the acquisition of conditioned taste aversion. The present study examined in rats the relationship between parabrachial neurons activated by systemic administration of bacterial cell-wall lipopolysaccharide or lithium chloride and the melanocortin system, a major regulator of feeding and energy homeostasis that also has been implicated in aversive behavior. Dual-labeling in situ hybridization showed melanocortin-4 receptor expression on neurons in the external lateral parabrachial subnucleus that displayed lipopolysaccharide- or lithium chloride-induced expression of c-fos mRNA. Melanocortin-4 receptor mRNA was also co-expressed with mRNA for calcitonin gene-related peptide in this subnucleus. Taken together with previous observations showing that calcitonin gene-related peptide expressing neurons in the external lateral parabrachial subnucleus are activated by peripheral immune challenge, that lipopolysaccharide-activated external lateral parabrachial subnucleus neurons project to the amygdala, and that the amygdala-projecting neurons in the external lateral parabrachial subnucleus are calcitonin gene-related peptide-positive, the present findings suggest the presence of a melanocortin-regulated calcitonin gene-related peptide-positive pathway from the external lateral parabrachial subnucleus to the amygdala that relays information of importance to forebrain responses to certain aspects of sickness behavior. These observations may thus help explain how melanocortins can reduce feeding and influence conditioned taste aversion during inflammation and other disease conditions.

Fatal progressive multifocal leukoencephalopathy in a patient with non-Hodgkin lymphoma treated with rituximab

We report a case of progressive multifocal leukoencephalopathy (PML) in a woman with non-Hodgkin lymphoma treated with chemotherapy in combination with rituximab. She presented with rapid deterioration of vision and subsequently cognitive decline. Magnetic resonance imaging (MRI) of the brain raised the suspicion of PML. The first PCR analysis of the cerebrospinal fluid (CSF) was negative, but a second sample was positive for JC virus DNA. Anti-viral treatment was ineffective and the patient died 7 months after debut of symptoms. Our case emphasizes the importance of the awareness of PML in patients with progressive neurological symptoms treated with antilymphocytic drugs and that consecutive CSF analyses may be needed to detect the JC virus.

Activation of the parabrachio-amygdaloid pathway by immune challenge or spinal nociceptive input: A quantitative study in the rat using Fos immunohistochemistry and retrograde tract tracing

Peripheral nociceptive stimulation results in activation of neurons in the pontine parabrachial nucleus (PB) of rats. Electrophysiological studies have suggested that noxiously activated PB neurons project to the amygdala, constituting a potential pathway for emotional aspects of pain. In the present study we examined this hypothesis by combining retrograde tract tracing with Fos immunohistochemistry. Cholera toxin subunit B was injected into the amygdala of rats. After a minimum of 48 hours the rats were given a subcutaneous injection of 100 μl of 5% formalin into one hindpaw and killed 60–90 minutes later. A dense aggregation of retrogradely labeled neurons was seen in the external lateral PB. Fos‐expressing neurons were present preferentially in the central, dorsal, and superior lateral subnuclei as well as in the lateral crescent area, as described previously. There was little overlap between the retrogradely labeled and Fos‐expressing populations and double‐labeled neurons were rare. In contrast, systemic immune challenge by intravenous injection of bacterial wall lipopolysaccharide resulted in a Fos expression that overlapped the retrograde labeling in the external lateral PB, and many double‐labeled neurons were seen. While these data provide direct functional anatomical evidence that nociceptive information from the hindlimb is relayed to the amygdala via the parabrachial nucleus, the number of parabrachio‐amygdaloid neurons involved is small. Considering the widespread activation of parabrachio‐amygdaloid neurons by a variety of visceral and humoral stimuli, the parabrachio‐amygdaloid pathway thus appears to be more involved in the mediation of information related to viscerally and humorally elicited activity than in transmission of spinal nociceptive inputs. J. Comp. Neurol. 481:210–219, 2005.

Feeding-related immune responsive brain stem neurons: association with CGRP.

Using dual-labeling in situ hybridization histochemistry, the neurotransmitter expression of immune-responsive neurons in the pontine parabrachial nucleus, a major relay for interoceptive information, was investigated. Intravenous injection of bacterial wall lipopolysaccharide resulted in dense c-fos mRNA expression in the external lateral parabrachial nucleus, and a majority of the c-fos expressing cells also expressed calcitonin gene-related peptide (CGRP) mRNA. In contrast CGRP-posi- tive cells in the adjoining external medial subnucleus were c-fos negative. Taken together with previous hodological and behavioral studies, these data suggest that CGRPergic parabrachial neurons may mediate lipopolysaccharide-induced anorexia by means of their projection to central nucleus of the amygdala.

Real-time PCR detection of human herpesvirus 1-5 in patients lacking clinical signs of a viral CNS infection.

BackgroundInfections of the central nervous system (CNS) with herpes- or enterovirus can be self-limiting and benign, but occasionally result in severe and fatal disease. The polymerase chain reaction (PCR) has revolutionized the diagnostics of viral pathogens, and by multiple displacement amplification (MDA) prior to real-time PCR the sensitivity might be further enhanced. The aim of this study was to investigate if herpes- or enterovirus can be detected in cerebrospinal fluid (CSF) from patients without symptoms.MethodsCerebrospinal fluid (CSF) samples from 373 patients lacking typical symptoms of viral CNS infection were analysed by real-time PCR targeting herpesviruses or enteroviruses with or without prior MDA.ResultsIn total, virus was detected in 17 patients (4%). Epstein-Barr virus (EBV) was most commonly detected, in general from patients with other conditions (e.g. infections, cerebral hemorrhage). MDA satisfactorily amplified viral DNA in the absence of human nucleic acids, but showed poor amplification capacity for viral DNA in CSF samples, and did not increase the sensitivity for herpes virus-detection with our methodology.ConclusionsViral pathogens are rarely detected in CSF from patients without signs of CNS infection, supporting the view that real-time PCR is a highly specific method to detect symptomatic CNS-infection caused by these viruses. However, EBV may be subclinically reactivated due to other pathological conditions in the CNS.

Preproenkephalin mRNA expression in rat parabrachial neurons: relation to cells activated by systemic immune challenge

By using a dual-labeling immunohistochemical/in situ hybridization technique we examined if enkephalin-expressing neurons in the pontine parabrachial nucleus, a major brain stem relay for ascending visceral and homeostatic information, were activated by systemic immune challenge. While rats subjected to intravenous injection of bacterial wall lipopolysaccharide expressed dense labeling for the immediate-early gene product FOS in parts of the parabrachial nucleus that also demonstrated dense preproenkephalin expression, only a small proportion of the enkephalin-positive neurons were FOS-positive. These data indicate that enkephalins, although implicated in a variety of autonomic responses, are not primarily involved in the transmission of immune-related information from the parabrachial nucleus to its different forebrain and brain stem targets.

Susceptibility testing breakpoints for Mycobacterium tuberculosis categorize isolates with resistance mutations in gyrA as susceptible to fluoroquinolones: implications for MDR-TB treatment and the definition of XDR-TB

OBJECTIVES Fluoroquinolones (FQs) are important in the treatment of MDR-TB and in the definition of XDR-TB. Our objective was to investigate how discrepancies in the phenotypic and genotypic methods for antimicrobial susceptibility testing could affect the interpretation of antimicrobial susceptibility test results. METHODS We analysed MICs of ofloxacin and levofloxacin in Middlebrook 7H10 broth (7H10) as well as sequencing of the quinolone resistance-determining region of the gyrA gene and the MTBDRsl assay in 75 resistant isolates, including MDR and XDR strains of Mycobacterium tuberculosis. RESULTS Among 75 resistant isolates, 27 had mutations associated with FQ resistance. Among isolates with resistance mutations in gyrA, 26% (seven of 27) were susceptible to levofloxacin and ofloxacin by phenotypic testing at 1 mg/L and 2 mg/L. The most common mutation was in codon 94 and these isolates had significantly increased MICs of levofloxacin (2-8 mg/L) compared with isolates with mutations in codon 90 (0.25-2 mg/L, P < 0.05). The sensitivity and specificity for the MTBDRsl assay compared with gyrA sequencing were 96% and 98%, respectively. CONCLUSION Current critical concentrations may classify up to 26% of isolates with gyrA mutations as susceptible to FQs due to a close relationship between susceptible and resistant populations. These results should be considered while improving clinical breakpoints for M. tuberculosis and may have an impact on the definition of XDR-TB.

Vitamin D enhances IL-1β secretion and restricts growth of Mycobacterium tuberculosis in macrophages from TB patients.

The emergence of multidrug-resistant strains of Mycobacterium tuberculosis (MTB), the bacterium responsible for tuberculosis (TB), has rekindled the interest in the role of nutritional supplementation of micronutrients, such as vitamin D, as adjuvant treatment. Here, the growth of virulent MTB in macrophages obtained from the peripheral blood of patients with and without TB was studied. The H37Rv strain genetically modified to express Vibrio harveyi luciferase was used to determine the growth of MTB by luminometry in the human monocyte-derived macrophages (hMDMs) from study subjects. Determination of cytokine levels in culture supernatants was performed using a flow cytometry-based bead array technique. No differences in intracellular growth of MTB were observed between the different study groups. However, stimulation with 100nM 1,25-dihydroxyvitamin D significantly enhanced the capacity of hMDMs isolated from TB patients to control the infection. This effect was not observed in hMDMs from the other groups. The interleukin (IL)-1β and IL-10 release by hMDMs was clearly increased upon stimulation with 1,25-dihydroxyvitamin D. Furthermore, the 1,25-dihydroxyvitamin D stimulation also led to elevated levels of TNF-α (tumor necrosis factor-alpha) and IL-12p40. It was concluded that vitamin D triggers an inflammatory response in human macrophages with enhanced secretion of cytokines, as well as enhancing the capacity of hMDMs from patients with active TB to restrict mycobacterial growth.

Alveolar macrophages from patients with tuberculosis exhibit reduced capacity of restricting growth of Mycobacterium tuberculosis : a pilot study of vitamin D stimulation in vitro

Background: The role of vitamin D supplementation as adjuvant treatment of tuberculosis (TB) has lately attracted increasing interest. Our aim was to investigate the capacity of alveolar macrophage ...

Tuberculous meningitis with positive cell-count in lumbar puncture CSF though negative cell-count from ventricular drainage CSF

Tuberculous meningitis with positive cell-count in lumbar puncture CSF though negative cell-count from ventricular drainage CSF