Immunohistochemical evidence for the involvement of protein convertases 5A and 2 in the processing of pro-neurotensin in rat brain

The neuropeptides/neurotransmitters neurotensin (NT) and neuromedin (NN) are synthesized by endoproteolytic cleavage of a common inactive precursor, pro-NT/NN. In vitro studies have suggested that the prohormone convertases PC5A and PC2 might both be involved in this process. In the present study, we used dual immunohistochemical techniques to determine whether either one or both of these two convertases were co-localized with pro-NT/NN maturation products and could therefore be involved in the physiological processing of this propeptide in rat brain. PC2-immunoreactive neurons were present in all regions immunopositive for NT. All but three regions expressing NT were also immunopositive for PC5A. Dual localization of NT with either convertase revealed that NT was extensively co-localized with both PC5A and PC2, albeit with regional differences. These results strongly suggest that PC5A and PC2 may play a key role in the maturation of pro-NT/NN in mammalian brain. The regional variability in NT/PC co-localization patterns may account for the region-specific maturation profiles previously reported for pro-NT/NN. The high degree of overlap between PC5A and PC2 in most NT-rich areas further suggests that these two convertases may act jointly to process pro-NT/NN. At the subcellular level, PC5A was largely co-localized with the mid-cisternae Golgi marker MG-160. By contrast, PC2 was almost completely excluded from MG-160-immunoreactive compartments. These results suggest that PC5A, which is particularly efficient at cleaving the two C-terminal-most dibasics of pro-NT/NN, may be acting as early as in the Golgi apparatus to release NT, whereas PC2, which is considerably more active than PC5A in cleaving the third C-terminal doublet, may be predominantly involved further distally along the secretory pathway to release NN.     

Reading abilities and cognitive functions of children with epilepsy: influence of epileptic syndrome

Children with epilepsy are at risk of developing learning disorders. To explore the influence of the epileptic syndrome on reading abilities, we have compared the neuropsychological profile of 12 children with benign idiopathic epilepsy with rolandic spikes, 10 with temporal lobe epilepsy and 12 with idiopathic generalized epilepsy. Children underwent a selection of standardised tests designed to assess: oral language, reading, short-term memory, attention and behavioural adjustment. Analysis of variance was adjusted according to age of onset of the epileptic syndrome, duration of the syndrome, and performance IQ for each group. Children with temporal lobe epilepsy (TLE) had significantly lower scores for reading speed and comprehension, but epileptic variables (the age of onset of epilepsy, duration and activity of epilepsy) had influenced academic performances. In the TLE group there was a clear effect of the topography of the epileptic foci (left-side TLE vs. right-side TLE) on reading profile. Furthermore, the effect of epileptic syndromes was found in phonological, semantic and verbal working memory deficits in the TLE group. To a lesser extent children with idiopathic generalized epilepsy (IGE) also exhibit cognitive deficit. The results of the present study lend support to epilepsy-specific patterns of neuropsychological dysfunction in children that should be considered to improve remediation of academic underachievement in these populations.     

The Estimation of Hepatic Blood Flow with Indocyanine Green: Comparison between the Continuous Infusion and Single Injection Methods

We compared the estimation of hepatic blood flow obtained using a continuous infusion of indocyanine green with that obtained after a single intravenous injection of indocyanine green in 35 patients with liver disease. There was no significant difference in the values of hepatic blood flow measured by these two methods, and there was a close correlation between the continuous infusion and single injection methods (r = 0.926, p <0.001). In a second group of nine patients with cirrhosis, we evaluated the effect of sampling from the right versus left hepatic vein on hepatic blood flow estimation. There was no significant difference between the two estimates and a good correlation was found (r = 0.878, p < 0.001). Since values of hepatic blood flow measured after a single indocyanine green injection are similar to those measured using the more classical continuous infusion method, the single injection method may be preferable since it requires only 15 min to be performed.     

Pharmacokinetics and metabolism of acetaminophen in normal, alcoholic and cirrhotic subjects

It is well known that a chemically reactive metabolite of acetaminophen formed in the liver can cause hepatic necrosis. The amount of cysteine and N-acetylcysteine derivatives excreted in the urine is an index of the amount of reactive metabolite produced. We have examined the pharmacokinetics and the pattern of acetaminophen metabolites in the urine, in 6 healthy controls, in 9 alcoholic subjects without liver disease, and in 11 patients with alcoholic cirrhosis but abstaining from alcohol. In alcoholics, oral clearance of the drug was similar to that of control subjects, but the amount of cysteine and N-acetylcysteine conjugates excreted in urine was significantly increased. In cirrhotics, the clearance of acetaminophen was decreased by 50 p. 100, but the pattern of urinary metabolites was unchanged. These results support previous anecdotal reports of increased acetaminophen hepatotoxicity in alcoholic subjects.     

Eosinophils stimulate fibroblast DNA synthesis

Fibrosis complicates a number of chronic inflammatory diseases and occurs in some conditions following chronic hypereosinophilic syndromes. We assessed whether eosinophils might be a source of fibrogenic factors. Extracts of human and guinea pig cell populations enriched for eosinophils contained substances that stimulated tritiated thymidine incorporation by human fibroblasts. Supernatants derived from resting eosinophils and extracts prepared from eosinophil granules also contained fibrogenic factors. Our findings demonstrate a new potential role for eosinophils and suggest a causal relationship between tissue eosinophilia and scar formation in certain parasitic conditions.     

Urban legends series: Sjögren’s syndrome

Oral Diseases (2012) 19 , 46–58 Sjögren’s syndrome (SjS) is one of the most common autoimmune rheumatic diseases, clinically characterized by xerostomia and keratoconjunctivitis sicca. We investigated the following controversial topics: (i) Do we have reliable ways of assessing saliva production? (ii) How important are the quantity and quality of saliva? (iii) Are only anti‐SSA/Ro and anti‐SSB/La relevant for the diagnosis of SjS? (iv) Are the American‐European Consensus criteria (AECC) the best way to diagnose SjS? Results from literature searches suggested the following: (i) Despite the fact that numerous tests are available to assess salivation rates, direct comparisons among them are scarce with little evidence to suggest one best test. (ii) Recent developments highlight the importance of investigating the composition of saliva. However, more research is needed to standardize the methods of analysis and collection and refine the quality of the accumulating data. (iii) In addition to anti‐Ro/La autoantibodies, anti α‐fodrin IgA and anti‐MR3 autoantibodies seem to be promising diagnostic markers of SjS, but more studies are warranted to test their sensitivity and specificity. (iv) AECC are classification, not diagnostic criteria. Moreover, recent innovations have not been incorporated into these criteria. Consequently, treatment directed to patients diagnosed using the AECC might exclude a significant proportion of patients with SjS.