Haemodynamic brain responses to acute pain in humans: sensory and attentional networks

Turning attention towards or away from a painful heat stimulus is known to modify both the subjective intensity of pain and the cortical evoked potentials to noxious stimuli. Using PET, we investigated in 12 volunteers whether pain-related regional cerebral blood flow (rCBF) changes were also modulated by attention. High (mean 46.6 degrees C) or low (mean 39 degrees C) intensity thermal stimuli were applied to the hand under three attentional conditions: (i) attention directed towards the stimuli, (ii) attention diverted from the stimuli, and (iii) no task. Only the insular/second somatosensory cortices were found to respond whatever the attentional context and might, therefore, subserve the sensory-discriminative dimension of pain (intensity coding). In parallel, other rCBF changes previously described as 'pain-related' appeared to depend essentially on the attentional context. Attention to the thermal stimulus involved a large network which was primarily right-sided, including prefrontal, posterior parietal, anterior cingulate cortices and thalamus. Anterior cingulate activity was not found to pertain to the intensity coding network but rather to the attentional neural activity triggered by pain. The attentional network disclosed in this study could be further subdivided into a non-specific arousal component, involving thalamic and upper brainstem regions, and a selective attention and orientating component including prefrontal, posterior parietal and cingulate cortices. A further effect observed in response to high intensity stimuli was a rCBF decrease within the somatosensory cortex ipsilateral to stimulation, which was considered to reflect contrast enhancing and/or anticipation processes. Attentional processes could possibly explain part of the variability observed in previous PET reports and should therefore be considered in further studies on pain in both normal subjects and patients with chronic pain.

Distribution of glutamic acid decarboxylase mRNA in the forebrain of the rainbow trout as studied by in situ hybridization

By using degenerate primers designed from glutamate decarboxylase (GAD) sequences of mammals, Xenopus and Drosophila, a 270-bp cDNA fragment was cloned by reverse transcriptase-polymerase chain reaction (RT-PCR) from cerebellum total RNA of rainbow trout. This partial cDNA shows 90% identity with mammalian GAD 65 and presents the Asn-Pro-His-Lys (NPHK) sequence corresponding to the pyridoxal-binding region of porcine DOPA decarboxylase or mammalian GAD. The distribution of GAD 65 mRNA-expressing neurons in the forebrain of the trout was studied by in situ hybridization using either digoxigenin- or 35S-labeled probes. The results demonstrate that gamma-amino butyric acid (GABA) neurons are widely distributed throughout the forebrain, with a high density in the periventricular regions. In this study, we report their precise distribution in the telencephalon and diencephalon. GAD mRNA-expressing cells were particularly abundant in the preoptic region and the mediobasal hypothalamus, two major neuroendocrine and estrogen-sensitive regions in fish. The presence of GAD mRNA-expressing neurons was observed in visually related structures such as the suprachiasmatic nucleus, the pretectal region, and the thalamus. Immunohistochemistry with antibodies directed against mouse GAD failed to demonstrate the presence of immunoreactive cell bodies, but showed a very high concentration of GAD-immunoreactive fibers in many brain regions, notably in the preoptic area, hypothalamus, and neurohypophyseal digitations of the pituitary, in particular in the proximal pars distalis. These results indicate that GABA neurons are ideally placed to modulate neuroendocrine activities at the hypothalamic and pituitary levels and to participate in the processing of sensorial information.

Eukaryotic conditional expression system

Existing conditional expression systems can be classified in two major categories that are based either on the induction or on the de-repression of transcription. The system described here combines both mechanisms, since a unique transcription factor can be shifted from a repression to a stimulation activity by simply changing its ligand. The resulting advantage of this system is the complete absence of basal expression before active induction. The principle of this method is based on the unexpected ability of the chimeric protein containing the DNA-binding domain of the yeast Gal4 transcription factor fused to the COOH half of the estradiol receptor (GalER), to act as a repressor when bound to the drug 4OH-tamoxifen, in the context of a previously described optimized Gal4-responsive promoter. The efficacy of this system has been assessed in transient expression assays using the chloramphenicol acetyl transferase (CAT), and in situ, through the activity of a Gal4 responsive beta-galactosidase gene.

Carcinoma associated paraneoplastic peripheral neuropathies in patients with and without anti-onconeural antibodies

OBJECTIVE

When to suspect a paraneoplastic disorder is a puzzling problem that has not recently been studied in a large series of patients referred for peripheral neuropathy.

METHODS

From 422 consecutive patients with peripheral neuropathy, 26 were analysed who concomitantly had carcinoma but no tumorous infiltration, drug toxicity, or cachexia. Their clinical, pathological, and electrophysiological data were analysed according to the presence of anti-onconeural antibodies, the latency between presentation and cancer diagnosis, and the incidence of carcinoma in the corresponding types of neuropathy of the population of 422 patients.

RESULTS

Seven patients (group I) had anti-onconeural antibodies (six anti-Hu, one anti-CV2) and 19 did not (groups IIA and B). In group I, subacute sensory neuropathy (SSN) was the most frequent but other neuropathies including demyelinating neuropathies were present. Patients in group II A had a short latency (mean 7.88 months), and a rapidly and usually severe neuropathy which corresponded in 11/14 to an established inflammatory disorder including neuropathy with encephalomyelitis, mononeuritis multiplex, and acute or chronic inflammatory demyelinating polyneuropathy (CIDP). Patients in group IIB had a long latency (mean 8.4 years) and a very chronic disorder corresponding in four of five to an axonal non-inflammatory polyneuropathy. In this population, the incidence of carcinoma occurring with a short latency was 47% in sensory neuronopathy, 1.7% in Guillain-Barré syndrome, 10% in mononeuritis multiplex and CIDP, and 4.5% in axonal polyneuropathy.

CONCLUSIONS

Paraneoplastic neuropathies associated with carcinoma are heterogeneous disorders. Neuropathies occurring with a long latency with tumours probably resulted from a coincidental association. Neuropathies which occurred within a few years of the tumour evolved rapidly and corresponded mostly to inflammatory disorders. As dysimmune neuropathies are probably paraneoplastic in a limited number of cases, patients with these disorders should probably not be investigated systematically for carcinoma in the absence of anti-onconeural antibodies, except when the neuropathy is associated with encephalomyelitis and probably with vasculitis. Questions remain concerning CIDP.

Central melatonin receptors in the rainbow trout: comparative distribution of ligand binding and gene expression

To better define the role of melatonin in fish, we have compared in detail the distribution of 2-[125I]iodomelatonin binding sites with gene expression for melatonin receptor subtypes in a widely studied seasonal species, the rainbow trout. Three distinct partial sequences of the melatonin receptor gene were cloned from trout genomic DNA. Two of the sequences corresponded to the Mella receptor subtype, and one corresponded to the Mellb receptor subtype. Analysis of numerous clones failed to find a sequence equivalent to the Mel1c receptor subtype. Comparison of receptor gene expression with 2-[125I]iodomelatonin binding distribution indicated dendritic transport of the receptor. Melatonin receptors were associated predominantly with visually related areas of the trout brain, such as the thalamic region, the pretectal area, and the optic tectum. The pituitary was devoid of 2-[125I]iodomelatonin binding, and melatonin receptor gene expression was not detectable. It would appear from the results of the present study that melatonin in this species is involved primarily in the processing of visual signals. How melatonin interacts with circannual rhythms of growth and reproduction is unclear, although a direct interaction between melatonin and the hypothalamo-pituitary axis is not clearly indicated.

IL-3-induced coexpression of histidine decarboxylase, IL-4 and IL-6 mRNA by murine basophil precursors

Murine low-density bone marrow cells sorted from the blast cell window on the basis of high rhodamine-123 retention (Rh-bright), are highly enriched in histamine-, IL-4-, and IL-6-producing cells. We established by in situ hybridization that up to 50% of this population (around 0.25% of the whole bone marrow) coexpressed the transcripts for these molecules upon stimulation with 1L-3. Rh-bright cells were also positive for mRNA encoding the alpha, beta, and gamma chains of the Fc(epsilon)RI which was functional since aggregated IgE induced the same percentage of cells hybridizing with the HDC probe as IL-3. Clonogenic progenitors and histamine- and cytokine-producing cells copurified in the Rh-bright population, but could be distinguished by their c-kit expression, CFU-C being more frequent in the c-kit(high) fraction, while histamine and IL-6 producers were enriched in the kit(low) counterpart. Ultrastructural analysis of Rh-bright cells revealed essentially two subsets, namely undifferentiated blast cells and basophil precursors. No other lineage-committed population was enriched by this sorting procedure, and it can therefore be concluded that coexpression of HDC, IL-6, and IL-4 transcripts in response to IL-3 or aggregated IgE takes place mainly in hematopoietic precursors belonging to the basophil lineage.

HSF1 activation occurs at different temperatures in somatic and male germ cells in the poikilotherm rainbow trout

The heat shock factor 1 (HSF1) is the central actor of the response to hyperthermia in eukaryotic cells. In mammals, male germ cells are an exception among all cellular populations for their HSF1 activation occurs at low temperature. This feature was believed to be specific of homeotherms whose testicular compartment is located outside the main body cavity, where temperature is lower. In the present study, we show that in the poikilotherm rainbow trout, the maximal heat shock response of male germ cells, that are located in the same body compartment than the other organs, occurs also at a significantly lower temperature (22 degrees C) than for somatic cells (28 degrees C), regardless of culture conditions before heat shock. In addition, the acquisition of the HSE-binding activity of HSF1 upon heat shock is not associated with the classical hsp70 mRNA accumulation. Taken together, these results strongly suggest the existence of a particular mode of heat shock response that could be specific of male germ cells but not restricted to homeotherms.

Effect of targeted expression of clusterin in photoreceptor cells on retinal development and differentiation

Clusterin expression is increased in tissues undergoing apoptosis, including neurodegenerative retina, but the causal relationships remain to be clarified. To test the hypothesis that overexpression of clusterin could induce apoptosis in neurons, transgenic mice were generated in which rat clusterin transgene was expressed in photoreceptor cells under the transcriptional control of the human interphotoreceptor retinoid-binding protein (IRBP) promoter. Photoreceptor cell death in the resulting transgenic mice was examined by histology and TUNEL techniques. The expression of the clusterin transgene was confirmed by in situ hybridization in the photoreceptor cells, and results in a complex pattern of clusterin protein distribution in the retina. A reduction in apoptotic staining in the transgenic retinas was observed from birth to postnatal day 15. These results suggest that clusterin is not causally involved in apoptotic mechanisms of photoreceptor cell death, but may relate to cytoprotective functions.

Higher detection rate of hepatitis G and C virus RNA in liver tissue than in serum of deceased injection drug users

To examine the prevalence of hepatitis G virus (HGV) and hepatitis C virus (HCV) infections in deceased injection drug users and for comparison of the detection rates of HGV and HCV RNA in liver tissue with detection rates in postmortem serum samples, RT-PCR was performed in 50 drug abuse-related fatalities. HGV RNA was detectable in liver tissue samples from 17/50 suddenly deceased drug abusers (34%). In 16 of these 17 positive cases, serum samples were also available but HGV RNA was detected in only 10. From 29/50 anti-HCV positive individuals, HCV RNA was detected in 23/50 liver tissue samples (46%), but HCV RNA was detectable in only 6/22 of the corresponding serum samples. In 12 anti-HCV positive cases (10 being also positive for HCV RNA in the liver), the examinations revealed a coinfection with HGV by detection of HGV RNA in the liver tissue samples. A significant association between the detection of HCV RNA in the liver and the occurrence of antibodies against the HCV NS4 protein, but not against HCV core antigen or NS3 protein was observed. The probability of anti-HCV and HCV RNA positivity increased with the age of the individuals. No HGV or HCV infection was detected in a control group of 50 persons who died suddenly by violent impact. The prevalence of active HCV and HGV infections in injection drug users detected by RT-PCR in liver tissue is in good accordance with data obtained from sera from living injection drug users. In contrast, the detection rate in postmortem serum samples was clearly lower. Possible reasons for this observation are discussed and the use of liver tissue for postmortem detection of hepatitis virus RNA is recommended.

Antiamphiphysin antibodies are associated with various paraneoplastic neurological syndromes and tumors

BACKGROUND

Antiamphiphysin antibodies react with a 128-kd protein found in synaptic vesicles. They were first described in patients with paraneoplastic stiff-man syndrome and breast cancer, but studies suggest that they can also occur in patients with other tumors and neurological disorders.

OBJECTIVE

To determine if antiamphiphysin antibodies are associated with various paraneoplastic neurological syndromes and tumors.

PATIENTS AND METHODS

Of 2800 serum samples tested by routine immunohistochemical procedures on sections of paraformaldehyde-fixed rat brain for the detection of autoantibodies associated with paraneoplastic neurological syndromes, 5 were selected because of labeling suggestive of antiamphiphysin antibodies and subsequently confirmed by the results of Western blot analysis using recombinant amphiphysin protein. Controls consisted of 40 patients with various nonparaneoplastic neurological diseases; 101 patients with cancer but without paraneoplastic neurological syndrome; 9 patients with small cell lung cancer, anti-Hu antibodies, and paraneoplastic neurological syndrome; 3 patients with M2-type antimitochondrial antibodies but no neurological disorder; and 30 normal subjects.

RESULTS

Of the 5 patients with antiamphiphysin antibodies, patient 1 had sensory neuronopathy, encephalomyelitis, and breast cancer; patient 2 had limbic encephalitis, and small cell lung cancer was detected in the mediastinum after 24 months of follow-up; patient 3 had encephalomyelitis and ovarian carcinoma; and patients 4 and 5 had Lambert-Eaton myasthenic syndrome and small cell lung cancer (patient 4 subsequently developed cerebellar degeneration). None of the 5 had stiffness. Two patients (Nos. 2 and 4) had antimitochondrial antibodies. The two patients (Nos. 4 and 5) with Lambert-Eaton myasthenic syndrome had antibodies directed against the voltage-gated calcium channel, and patient 2 subsequently developed anti-Hu antibodies. In the controls, antiamphiphysin antibodies were detected by Western blot analysis in 3 of 8 patients with anti-Hu antibodies, but in none of the other groups.

CONCLUSIONS

These data indicate that antiamphiphysin antibodies are not specific for one type of tumor or one neurological syndrome and can be associated with other neural and nonneural antibodies. The simultaneous association of several antibodies in some patients suggests multimodal autoantibody production.

Regulation by pH of the alternative splicing of the stem cell factor pre-mRNA in the testis

Proliferation and differentiation of progenitor stem cells are mainly controlled by diffusible and adhesion molecules. Stem cell factor (SCF), an essential regulator of spermatogenesis produced by Sertoli cells, utilize both modes of cell to cell communication. Indeed, SCF exists in soluble (SCFs) and membrane-bound (SCFm) forms, which are required for a complete spermatogenesis, and are generated by alternative splicing of optional exon 6, encoding sites of proteolysis. We show that in the mouse testis, the alternative splicing of SCF is developmentally regulated. SCFs predominates in fetal and neonatal gonads and is then replaced by SCFm in the prepubertal and adult gonads. By sequencing SCF exon 6, we show that the flanking intronic sequences perfectly follow the gt-at rule, suggesting that the basal splicing machinery might not be responsible by itself for exon 6 skipping. Moreover, freshly isolated Sertoli cells mainly express SCFm, but a switch to SCFs occurs after 48 h of culture. We found that this change can be prevented by acidification of the culture medium at pH 6.3 or by addition of lactate. The sustained synthesis of SCFm at low pH was no longer observed in the presence of cycloheximide, suggesting that SCF exon 6 skipping requires de novo protein synthesis. Accordingly, UV cross-linking experiments show that nuclear Sertoli cell protein(s) bind in a sequence-specific manner to exon 6. Together, our data allow the proposal of an integrated mechanism in which the synthesis of lactate by Sertoli cells is used in the same time as an energetic substrate for germ cells and as a promoter of their survival/proliferation through the production of SCFm.

Technetium-99m sestamibi brain single-photon emission tomography for detection of recurrent gliomas after radiation therapy

Technetium-99m sestamibi (MIBI), an alternative radiopharmaceutical for myocardial perfusion imaging, has also been proposed for use as an imaging agent for various tumours, including breast cancer, lung cancer, lymphomas, melanomas and brain tumours. After routine radiation therapy, deteriorating clinical status or treatment failure may be due to either radiation-induced changes or recurrent tumour. Computed tomography and magnetic resonance imaging offer imperfect discrimination of tumour viability and radionecrosis. Against this background we undertook a retrospective study of 35 malignant glioma patients in whom clinical deterioration had occurred, in order to clarify the value of 99mTc-MIBI SPET in identifying tumour recurrence. SPET was performed 15 min after intravenous injection of 1110 MBq with a dual-headed gamma camera using a fan-beam collimator. Transverse, coronal and sagittal views were reconstructed. Intense MIBI uptake was found in 31 patients. This uptake was correlated with tumour recurrence as proved by histology and/or rapid, fatal evolution of these cases. The statistical analysis performed on this population of patients with MIBI uptake revealed a group of patients with a long mean survival and a group with a short mean survival. Two subgroups were found within each of these groups, according to the functional index ratio (tumour uptake/pituitary gland uptake ratio). No MIBI uptake was found in four patients who are still alive and can be considered to be disease-free. In those cases showing MIBI uptake, death occurred an average of 6.69 months following brain SPET. According to our results, the specificity and sensitivity of 99mTc-MIBI brain SPET seem to be high. Moreover, this technique is more accurate than computed tomography or magnetic resonance imaging for discriminating between tumour recurrence and radionecrosis.

[Prolonged curarization with suxamethonium in a four-week old infant]

A case of a 28-day-old infant who developed suxamethonium apnoea is described. He was found to be homozygous for atypical cholinesterase. Main characteristics of this disorder are reviewed. Other causes of prolonged apnoea in infants recovering from anaesthesia for surgery of pyloric stenosis are discussed.

Functional regions of the human cytomegalovirus protein pUL97 involved in nuclear localization and phosphorylation of ganciclovir and pUL97 itself

In order to identify functional regions of the human cytomegalovirus protein pUL97 (i) different 5' fragments of the UL97 open reading frame (ORF) were fused to the coding region of the green fluorescent protein and (ii) recombinant vaccinia viruses (rVV) were generated carrying two full-length and 11 mutated UL97 ORFs. The results indicated the presence of an N-terminal region within pUL97 which changed the intracellular distribution of the fusion proteins. pUL97 was localized in the nucleus, but not in the nucleoli, and was detected in the nuclear matrix fraction. Expression of all pUL97 mutants could be confirmed by Western blot analysis. pUL97-associated ganciclovir (GCV) phosphorylation in rVV-infected cells, determined quantitatively by HPLC analysis, was abolished completely using individual UL97 deletion mutants. Phosphorylation of full-length and some of the mutated pUL97 was detected in cells infected with the rVVs. The UL97 constructs carrying point mutations from GCV-resistant HCMV isolates at positions 460M, 520H, 594V, and the 4 aa deletion 590AACR593, also resulted in decreased but not abolished phosphorylation of GCV in the rVV system, whereas the phosphorylation of pUL97 itself was not influenced. The rVV system is a suitable method for quantitatively testing the functional relevance of pUL97 mutations.

Paraneoplastic demyelinating neuropathy, subacute sensory neuropathy, and anti-Hu antibodies: clinicopathological study of an autopsy case

A patient with anti-Hu antibodies, small-cell lung carcinoma, and autopsy-proven subacute sensory neuropathy had early slowing of motor and sensory conduction velocities. In the peripheral nerves, chronic demyelinating and remyelinating lesions with axonal degeneration were associated with an inflammatory reaction consisting of CD8+ T cells and CD68+ macrophages. On immunohistochemical testing, the patient's serum did not react with normal nerve, suggesting that the Hu proteins were not the target of the inflammatory reaction in the nerve.

Striking evolutionary conservation of a cis-element related to nuclear receptor target sites and present in TR2 orphan receptor genes

A systematic scanning of nucleic acid databases for DNA elements made of combinations of RGGTCA nuclear receptor half sites, has revealed that identical 19 nucleotide-long motifs composed of two inverted RGGTCA sites with a spacing of 7 nucleotides (IR7), are present upstream of the regions coding for the human TR2 and of the sea urchin SpSHR2 orphan receptors. We have developed an experimental strategy based on PCR, to check if this IR7 could correspond to an unusually long cis-element, conserved along evolution and regulating the TR2 genes. We found that indeed IR7 is present in the 5' untranslated region of TR2 genes from all species tested, including Xenopus, rainbow trout, zebrafish and mouse. The exact conservation throughout the animal kingdom of such a long, non repetitive and non coding genomic region, highly suggests that it should ensure important biological functions. In addition, this work has allowed the identification of a new, non coding, upstream exon in the mouse TR2 gene present in testicular TR2 mRNAs.

Allodynia after lateral-medullary (Wallenberg) infarct. A PET study

We used PET to study regional cerebral blood flow (rCBF) changes in nine patients with unilateral central pain after a lateral medullary infarct (Wallenberg's syndrome). All patients presented, on the abnormal side, a combination of hypaesthesia to noxious and thermal stimuli and allodynia to rubbing of the skin with a cold object (i.e. abnormal pain to innocuous stimulation). The rCBF responses during allodynia were compared with those obtained during stimulation of the normal side using (i) a cold non-noxious stimulus identical to that applied to the painful side, and (ii) an electrical high-frequency stimulus at painful ranges. Statistical analysis disclosed two abnormal patterns of rCBF change during allodynia. First, there is a quantitative change whereby the blood flow response was out of proportion with the actual intensity of the stimulus, i.e. the pattern of activation by innocuous rubbing of the skin was in our patients identical to that previously reported in response to painful stimuli in normal subjects. This pattern concerned primarily the contralateral thalamus in its lateral half and the primary and somatosensory areas, as well as inferior parietal [Brodmann area (BA) 39/40], anterior insular (BA 6) and medial prefrontal (BA 10) cortices. Thalamic over-activity may reflect abnormal transduction and amplification of sensory inputs after spinothalamic deafferentation. This might be responsible for both increased rCBF in multiple cortical targets and the perceived shift of stimulus intensity from innocuous to painful ranges. The second abnormality associated with allodynic sensation was qualitative. It concerned exclusively the contralateral cingulate gyrus, which did not exhibit the usual pain-related rCBF increase reported in normal subjects. This abnormal cingulate response may account for the peculiar response of lateral medullary infarct patients to allodynic pain, which is not simply perceived as an exaggerated pain sensation, but as a new, strange and extremely unpleasant feeling, not previously experienced by the patients.

HCV and HGV in B-cell non-Hodgkin's lymphoma

BACKGROUND/AIMS

A causative role of hepatitis C virus infection (HCV) has been discussed in the pathogenesis of mixed cryoglobulinaemia and in B-cell non-Hodgkin's lymphoma. No data are available concerning the newly discovered hepatitis G virus (HGV) and extrahepatic manifestations such as haematological malignancies. But, HCV and HGV most probably belong to the same family of Flavivirus. Consequently, we looked for the prevalence of HCV, HGV and cryoglobulins in patients with B-cell non-Hodgkin's lymphoma.

METHODS

Serum samples from 69 patients with non-Hodgkin's lymphoma were studied. Diagnosis of non-Hodgkin's lymphoma was established according to the Kiel classification. Active HCV- and HGV infections were investigated using polymerase chain reaction for detection of viral RNA. Cryoglobulins were detected from serum and monoclonal immunoglobulin components were analysed with immunofixation electrophoresis. In addition, we assessed the clinical course of HCV- and HGV-infected patients under chemotherapy.

RESULTS

Three of 69 (4.3%) patients with B-cell non-Hodgkin's lymphoma were HCV-infected and nine non-Hodgkin's lymphoma patients (13.0%) were positive for hepatitis G virus RNA. All HGV infected patients were suffering from low-grade non-Hodgkin's lymphoma. No HGV-infected patient was co-infected by HCV and neither HCV- nor HGV-infected patients showed clinical signs of chronic liver disease before, during or after chemotherapy. Serum samples from all patients were devoid of cryoglobulins.

CONCLUSIONS

HCV seems to have no significance for the pathogenesis of non-Hodgkin's lymphoma in Germany. The increased prevalence of hepatitis G (16.3%) in patients with low-grade non-Hodgkin's lymphoma could suggest a pathological consequence of HGV infection outside of the liver. Evidence of clinically relevant hepatic disease in HGV infected patients was not obtained. Further, chemotherapy does not seem to affect the subsequent clinical course of HGV infection.