Genotype-phenotype correlation in von Hippel-Lindau families with renal lesions

von Hippel-Lindau (VHL) disease arises from mutations in the VHL gene and predisposes patients to develop a variety of tumors in different organs. In the kidney, single or multiple cysts and renal cell carcinomas (RCC) may occur. Both inter- and intrafamilial heterogeneity in clinical expression are well recognized. To identify VHL-dependent genetic factors, we investigated the renal phenotype in 274 individuals from 126 unrelated VHL families in whom 92 different VHL mutations were characterized. The incidence of renal involvement was increased in families with mutations leading to truncated protein (MLTP) or large rearrangement, as compared to families with missense changes (81 vs. 63%, respectively; P=0.03). In the latter group, we identified two mutation cluster regions (MCRs) associated with a high risk of harboring renal lesions: MCR-1 (codons 74-90) and MCR-2 (codons 130-136). In addition, the incidence of RCC was higher in families with MLTP than in families with missense changes (75 vs. 57%; P=0.04). Furthermore, mutations within MCR-1 but not MCR-2 conferred genetic susceptibility to develop RCC. Overall, our data argued for a substantial contribution of the genetic change in the VHL gene to susceptibility to renal phenotype in VHL patients.     

The optimal usage of the ISCP by trainee and trainer

The Intercollegiate Surgical Curriculum Programme (ISCP) provides the Curriculum with the specialty syllabus, trainee’s portfolio of activity, and the process and recording of assessment. It is an excellent resource and in order to gain the optimal benefit trainees and trainers are recommended to invest some time in navigating through the site and understand its functionality. The launch of the 2021 Surgical Curricula is an important change with the new assessment tool of the Multiple Consultant Report (MCR) and the trainee input with their self-assessment. The ISCP has incorporated the MCR assessment process (Generic Professional Capabilities and Capabilities in Practice) into the learning agreement structure such that the progression through to the higher-level outcome of the curriculum, defined as a day 1 consultant in a specialty, is enhanced by frequent and focussed feedback specific to the trainee. To achieve the optimal outcomes, it is important to have strong engagement with the ISCP and the useability has been enhanced to facilitate this.     

Rapid Polymyxin NP test for the detection of polymyxin resistance mediated by the mcr-1/mcr-2 genes

The Rapid Polymyxin NP test has been recently developed to rapidly detect polymyxin resistance in Enterobacteriaceae. Here we evaluated this test for detecting MCR-1/MCR-2-producing Enterobacteriaceae using a collection of 70 non-redundant strains either recovered from the environment, animals, or humans. Sensitivity and specificity were found to be 100%.     

Development and validation of a multiplex polymerase chain reaction assay for detection of the five families of plasmid-encoded colistin resistance

Plasmid-mediated colistin resistance is increasingly described worldwide in Enterobacteriaceae from animal and human isolates. Diffusion of these resistance traits among carbapenem-resistant enterobacterial isolates is of particular concern as colistin has become the last resort antibiotic for treating human infections with these organisms. Therefore, being able to monitor the presence of these transferable colistin resistance genes (mcr-1 to mcr-5-variants) is crucial. This paper describes the development of a multiplex polymerase chain reaction (PCR) protocol for detection of all currently known transferable colistin resistance genes in Enterobacteriaceae. Five primer pairs were designed to amplify mcr-1, mcr-2, mcr-3, mcr-4 and mcr-5 gene products in a multiplex PCR. This assay was validated retrospectively on colonies of 50 Escherichia coli, 44 Klebsiella pneumoniae and 12 Salmonella enterica isolates of animal and human origin, all well characterized, and validated prospectively on 450 carbapenem-resistant enterobacterial isolates received by the French National Reference Centre. In addition, 82 Aeromonas spp. and 10 Shewanella spp. known to be the progenitors of mcr-3 and mcr-4 alleles, respectively, were screened. Mcr-multiplex PCR assay displayed 100% specificity, sensitivity, negative predictive value and positive predictive value. The assay was able to detect all variants of the different mcr alleles, and was able to detect chromosomally encoded mcr-4-like variants present in two Shewanella bicestrii JAB-1 and Shewanella woodyi S539. In conclusion, a rapid and robust multiplex PCR assay able to detect all known mcr gene families described in Enterobacteriaceae was developed and validated. This type of test is critical for the epidemiological surveillance of plasmid-encoded resistance, especially in carbapenem-resistant bacteria.     

Do we know all there is to know about Familial Adenomatous Polyposis?

Familial Adenomatous Polyposis (FAP) and Attenuated FAP (AFAP) are caused by a germline mutation in the Adenomatous polyposis coli (APC) gene. Recently, a new pathway characterized by a biallelic mutation in the MYH gene, with a recessive model of inheritance was discovered for this inherited syndrome. This report describes a Tunisian patient with an attenuated FAP phenotype, presenting seven colon polyps and an adenocarcinoma but no detectable germline mutations in the FAP target genes. A well known somatic mutation was found in the APC mutation cluster region (MCR). This case shows that further studies are needed to fully understand all the pathways of the FAP syndrome.     

The role of NPY in hypothalamic mediated food intake

Neuropeptide Y (NPY) is a highly conserved neuropeptide with orexigenic actions in discrete hypothalamic nuclei that plays a role in regulating energy homeostasis. NPY signals via a family of high affinity receptors that mediate the widespread actions of NPY in all hypothalamic nuclei. These actions are also subject to tight, intricate regulation by numerous peripheral and central energy balance signals. The NPY system is embedded within a densely-redundant network designed to ensure stable energy homeostasis. This redundancy may underlie compensation for the loss of NPY or its receptors in germline knockouts, explaining why conventional knockouts of NPY or its receptors rarely yield a marked phenotypic change. We discuss insights into the hypothalamic role of NPY from studies of its physiological actions, responses to genetic manipulations and interactions with other energy balance signals. We conclude that numerous approaches must be employed to effectively study different aspects of NPY action.     

Molecular biology and physiology of the melanocortin system in fish: a review

The melanocortin system consists of melanocortin peptides derived from the proopiomelanocortin gene (in particular adrenocorticotropic hormone, ACTH, and melanocyte-stimulating hormones, MSH) and five melanocortin receptor subtypes (MC1R-MC5R). Knowledge of the melanocortin system in fish is still limited, but information on the receptor part of the system is very rapidly growing. The melanocortin receptors (MCRs) have been recently cloned from several species of fish. The amino acid sequences appear remarkably well conserved. Pharmacological characterisation studies of the first identified piscine MCRs indicate that ACTH may be the original ligand for the MCRs, while the MSH peptides gained specialised functions in the course of evolution. Considering the tissue distribution of the MCRs, there are two distinctions between mammals and fish: where in mammals the MC4R is exclusively expressed in the central nervous system, in the fish species examined so far it is also peripherally expressed. It does however, alike the situation in mammals, likely play a key role in the central regulation of food intake and energy balance. Not only the MCRs, but also many other factors involved herewith, have been found in fish and roughly appear to function similarly as in mammals. The second difference is the distribution of the MC5R, which appears less widely expressed in fish than in mammals. Considering the available data it is predicted that, in mammals and fish alike, skin colouration is mediated via MC1R and steroidogenesis via MC2R. This review provides a short overview of the basic molecular characteristics, pharmacology, and tissue distribution of the MCRs in the fish investigated up to now, as well as their physiological role in the processes of skin colouration, steroidogenesis, and feeding behaviour.     

Relationship between prolactin in the serum and cerebrospinal fluid of ovariectomized female rhesus monkeys

The entry of prolactin into the cerebrospinal fluid from the blood, and the relation between levels in the two compartments were studied under a variety of conditions in ovariectomized rhesus monkeys. Prolonged treatment with either domperidone or sulpiride, both dopamine-receptor blockers, elevated prolactin levels in serum and cerebrospinal fluid proportionately equally, so that the cerebrospinal fluid/serum ratio was unchanged from controls (circa 12–20%). Gel filtration showed that only ‘little’ (monomeric) prolactin entered the cerebrospinal fluid in such monkeys. Following acute elevations of blood prolactin after a single injection of either sulpiride or ovine prolactin, cerebrospinal fluid levels increased linearly over a 90 min sampling period, despite falling serum levels. The rate of entry of prolactin into the cerebrospinal fluid was similar after either procedure, and was independent of absolute serum or cerebrospinal fluid levels, suggesting a rate-limiting mechanism. Furthermore, retrograde portal blood flow from the pituitary is not necessary to account for these results. Clearance of prolactin from the third ventricle was studied following intraventricular injection of prolactin. Prolactin was removed from the cerebrospinal fluid by a mechanism whose efficiency compares with that in serum, so that the half-life of prolactin in either compartment is about the same.Measurement of sodium, potassium and calcium in the cerebrospinal fluid during prolonged hyperprolactinaemia showed no change, indicating that the central effects of prolactin are not due to alteration of these electrolytes.These results show that cerebrospinal fluid levels of prolactin, and hence, those surrounding the brain, can be inferred accurately from those in the blood, and suggest that there may be a selective mechanism regulating the entry of prolactin into the cerebral compartment.