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Faerch M, Christensen JH, Rittig S, Johansson J-O, Gregersen N, de Zegher F, Corydon TJ. Diverse vasopressin V2 receptor functionality underlying partial congenital nephrogenic diabetes insipidus. Am J Physiol Renal Physiol 297: F1518-F1525, 2009. First published October 7, 2009; doi: 10.1152/ajprenal.00331.2009.--X-linked congenital nephrogenic diabetes insipidus (CNDI) is characterized by a defective renal response to the antidiuretic hormone (AVP) due to variations in the arginine vasopressin receptor 2 (AVPR2) gene. In a unique group of patients, the renal insensitivity to the effects of AVP is incomplete resulting in a partial phenotype. To investigate the molecular defects, two previously published variations in the AVPR2 gene, known to cause a partial CNDI phenotype, were expressed in transiently transfected human embryonic kidney cells. One variation (p.Argl04Cys) is located in the first extracellular loop and the other variation (p.Ser329Arg) is located in the intracellular COOH terminal of the receptor protein. Western blotting showed almost equal amounts of WT-V2R and Argl04Cys-V2R protein at steady state, whereas the level of Ser329Arg-V2R protein was lower. Confocal microscopy established that WT-V2R and Arg 104Cys-V2R are localized on the cellular surface while the Ser329Arg-V2R primarily accumulates within the endoplasmic reticulum resulting in reduced surface expression. Ligand binding analysis demonstrated that the [B.sub.max] for cells expressing Argl04Cys-V2R and Ser329ArgV2R were 14.8- and 2.5-fold lower than [B.sub.max] for WT-V2R, respectively. AVP affinity (1/[K.sub.d]) for WT-V2R and the Ser329Arg-V2R was similar while 1/[K.sub.d] for Argl04Cys-V2R was increased, cAMP assay revealed that cells expressing p.Argl04Cys-V2R or p.Ser329ArgV2R produced 1.7- and 6.8-fold lower amounts of cAMP compared with WT-V2R, respectively. In conclusion, ligand binding and signal transduction capability are dependent on localization of the amino acid variation. Striking divergences at the level of receptor functionality may thus underlie similar clinical phenotypes in CNDI. partial phenotype; arginine vasopressin receptor type 2; heterologous expression doi: 10.1152/ajprenal.00331.2009

Objective: Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is characterized by severe polyuria and polydipsia and is caused by variations in the gene encoding the AVP prohormone. This study aimed to ascertain a correct diagnosis, to identify the underlying genetic cause of adFNDI in a Swedish family, and to test the hypothesis that the identified synonymous exonic variant in the AVP gene (c.324G>A) causes missplicing and endoplasmic reticulum (ER) retention of the prohormone. Design/Patients: Three affected family members were admitted for fluid deprivation test and dDAVP (1-deamino-8-d-arginine-vasopressin) challenge test. Direct sequencing of the AVP gene was performed in the affected subjects, and genotyping of the identified variant was performed in family members. The variant was examined by expression of AVP minigenes containing the entire coding regions as well as intron 2 of AVP. Methods/Results: Clinical tests revealed significant phenotypical variation with both complete and partial adFNDI phenotype. DNA analysis revealed a synonymous c.324G>A substitution in one allele of the AVP gene in affected family members only. Cellular studies revealed both normally spliced and misspliced pre-mRNA in cells transfected with the AVP c.324G>A minigene. Confocal laser scanning microscopy showed collective localization of the variant prohormone to ER and vesicular structures at the tip of cellular processes. Conclusion: We identified a synonymous variant affecting the second nucleotide of exon 3 in the AVP gene (c.324G>A) in a family in which adFNDI segregates. Notably, we showed that this variant causes partial missplicing of pre-mRNA, resulting in accumulation of the variant prohormone in ER. Our study suggests that even a small amount of aberrant mRNA might be sufficient to disturb cellular function, resulting in adFNDI. [ABSTRACT FROM AUTHOR]

Background: Apolipoprotein E (ApoE) has been extensively studied in Alzheimer's disease (AD), but little is known of apolipoprotein A-I (ApoA-I) in cerebrospinal fluid (CSF).Objective: Plasma lipids as well as ApoA-I and ApoE in plasma and CSF were determined and related to Mini-Mental State Examination (MMSE) score, APOE genotype, and CSF AD biomarkers.Methods: Consecutive patients with AD (n = 29), stable mild cognitive impairment (n = 13), other dementias (n = 14), and healthy controls (n = 18) were included at a single center.Results: AD patients had higher plasma triglycerides and lower CSF ApoA-I concentration than controls (both p < 0.05). CSF ApoE concentration was reduced in other dementias (p < 0.01). In AD as well as other dementias, the ratios between CSF and plasma concentrations of both ApoA-I and ApoE were lower than those in the controls. ApoA-I and ApoE in plasma and CSF were not influenced by APOEɛ4 allele distribution. In the total study population (n = 74), CSF ApoA-I correlated positively with MMSE score (r = 0.26, p < 0.05) and negatively with CSF P-tau (r = -0.25, p < 0.05). CSF ApoE correlated positively with CSF concentrations of T-tau and P-tau in the total study population and in AD patients.Conclusion: CSF ApoA-I was reduced in AD patients and associated with measures of cognitive function and AD disease status. The mechanisms underlying the decreased CSF:plasma ratios of ApoA-I and ApoE in AD and other dementias need to be explored in further studies. [ABSTRACT FROM AUTHOR]

Background: The role of inflammation in Alzheimer’s disease (AD) and other cognitive disorders is unclear. In a well-defined mono-center population, we measured cytokines and chemokines in paired serum and cerebrospinal fluid (CSF) samples. Methods: Consecutive patients with AD (n = 30), stable mild cognitive impairment (SMCI, n = 11), other dementias (n = 11), and healthy controls (n = 18) were included. None of the subjects was treated with glucocorticoids, cholinesterase inhibitors, or non-steroidal anti-inflammatory drugs. Serum and CSF concentrations of interleukin-6 (IL-6), IL-8, IL-12/23 p40, IL-15, IL-16, vascular endothelial growth factor-A (VEGF-A), and three chemokines were measured using a multiplex panel. Results: After correction for multiple comparisons, only CSF IL-12/23 p40 concentration differed significantly between the total patient group (n = 52) and controls (n = 18; p = 0.002). Further analyses showed that CSF IL-12/23 p40 concentration was decreased in all patient subgroups (AD, other dementias, and SMCI) compared to healthy controls (p < 0.01, p < 0.05, and p < 0.05, respectively). In the total study population (n = 70), CSF IL-12/23 p40 concentrations correlated positively with CSF concentrations of β-amyloid1-42 (Aβ1–42) and phosphorylated tau protein (P-tau) whereas in AD patients (n = 30), CSF IL-12/23 p40 only correlated positively with CSF P-Tau (r = 0.46, p = 0.01). Conclusions: Most cytokines and chemokines were similar in patients and controls, but CSF IL-12/23 subunit p40 concentration was decreased in patients with cognitive impairment, and correlated with markers of AD disease status. Further studies are needed to evaluate the role of CSF IL-12/23 p40 in other dementias and SMCI. [ABSTRACT FROM AUTHOR]

Background: Insulin-like growth factor-II (IGF-II) is important for brain development. Although IGF-II is abundant also in adult life, little is known of the role of IGF-II in Alzheimer's disease (AD).Objective and Methods: This was a cross-sectional study of 60 consecutive patients under primary evaluation of cognitive impairment and 20 healthy controls. The patients had AD dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n = 32), stable MCI (SMCI, n = 13), or other dementias (n = 15). IGF-II, IGF-binding protein-1 (IGFBP-1), and IGFBP-2 were analyzed in serum and cerebrospinal fluid (CSF).Results: Levels of IGF-II, IGFBP-1, and IGFBP-2 were similar in all groups in the total study population. Gender-specific analyses showed that in men (n = 40), CSF IGF-II level was higher in AD compared to SMCI and controls (p <  0.01 and p <  0.05, respectively). Furthermore, CSF IGFBP-2 level was increased in AD men versus SMCI men (p <  0.01) and tended to be increased versus control men (p = 0.09). There were no between-group differences in women (n = 40). In the total study population (n = 80) as well as in men (n = 40), CSF levels of IGF-II and IGFBP-2 correlated positively with CSF levels of the AD biomarkers total-tau and phosphorylated tau protein.Conclusion: In men, but not women, in the early stages of AD, CSF IGF-II level was elevated, and CSF IGFBP-2 level tended to be increased, compared to healthy controls. [ABSTRACT FROM AUTHOR]

The cerebrospinal fluid (CSF) biomarkers amyloid-β (Aβ)1-42, T-tau, and P-tau have good diagnostic accuracy for clinically diagnosed Alzheimer's disease (AD). However, in multi-center studies, the predictive values of the CSF biomarkers have been lower, possibly due to differences in procedures for lumbar puncture and CSF handling and storage, and to differences in patient populations, clinical evaluations, and diagnostic procedures. Here we investigate the diagnostic accuracy of CSF biomarkers in a well defined homogeneous mono-center population. We also evaluate an extended panel of amyloid related biomarkers. Sixty consecutive patients admitted for cognitive impairment to a memory clinic were recruited. The participants included patients with AD or mild cognitive impairment (MCI) diagnosed with AD upon follow-up (n = 32), patients with stable MCI (n = 13), patients with other dementias diagnosed at primary evaluation or upon follow-up (n = 15), and healthy controls (n = 20). CSF was analyzed for Aβ1-42, T-tau, P-tau, AβX-38, AβX-40, AβX-42, sAβPPα, and sAβPPβ. In multivariate analysis, the core biomarkers Aβ1-42, T-tau, and P-tau demonstrated a high ability to diagnose AD versus the combined groups of controls and stable MCI, with an area under the receiver operating characteristic curve (AUROC) of 0.97 (95% CI 0.93-1.00, p < 0.0001). The additional biomarkers only marginally increased AUROC to 0.98 (95% CI 0.95-1.00, p < 0.0001), this increase mainly mediated by AβX-42. In conclusion, CSF biomarkers Aβ1-42, T-tau, and P-tau have very high diagnostic accuracy in a well defined cohort of untreated patients, demonstrating the excellent potency of CSF biomarkers to identify pathological processes in AD when a stringent analytical protocol is used. [ABSTRACT FROM AUTHOR]

Much is unknown regarding the regulation of Alzheimer-related amyloid-β protein precursor (AβPP)-processing in the human central nervous system. It has been hypothesized that amyloidogenic AβPP-processing preferentially occurs in the regulated secretory pathway of neurons. To test this hypothesis we looked for correlations of AβPP-derived molecules in cerebrospinal fluid (CSF) with chromogranin (Cg) derived peptides, representing the regulated secretion. Patients with Alzheimer's disease (AD, N=32), multiple sclerosis (MS, N=50), and healthy controls (N= 70) were enrolled. CSF was analyzed for the amyloid peptides Aβ1-42, Aβx-42, Aβx-40, Aβx-38, α-cleaved soluble AβPP (sAβPPα), β-cleaved soluble AβPP (sAβPPβ), and peptides derived from CgB and SgII (Secretogranin-II, CgC). We investigated CSF levels of the protease BACE1, which processes AβPP into Aβ, in relation to Cg-levels. Finally, we measured Cg levels in cell media from untreated and BACE1-inhibited SH-SY5Y human neuroblastoma cells. CSF Cg levels correlated to sAβPP and Aβ peptides in AD, MS, and controls, and to CSF BACE1. Cell medium from BACE1-inhibited cells had decreased CgB levels. These results suggest that a large part of AβPP in the human central nervous system is processed in the regulated secretory pathway of neurons. [ABSTRACT FROM AUTHOR]

X-linked congenital nephrogenic diabetes insipidus (CNDI) is characterized by a defective renal response to the antidiuretic hormone (AVP) due to variations in the arginine vasopressin receptor 2 (A VPR2) gene. In a unique group of patients, the renal insensitivity to the effects of AVP is incomplete resulting in a partial phenotype. To investigate the molecular defects, two previously published variations in the AVPR2 gene, known to cause a partial CNDI phenotype, were expressed in transiently transfected human embryonic kidney cells. One variation (p.Arg104Cys) is located in the first extracellular loop and the other variation (p.Ser329Arg) is located in the intracellular COOH terminal of the receptor protein. Western blotting showed almost equal amounts of WT-V2R and Arg104Cys-V2R protein at steady state, whereas the level of Ser329Arg-V2R protein was lower. Confocal microscopy established that WT-V2R and Arg104Cys-V2R are localized on the cellular surface while the Ser329Arg-V2R primarily accumulates within the endoplasmic reticulum resulting in reduced surface expression. Ligand binding analysis demonstrated that the Bmax for cells expressing Arg104Cys-V2R and Ser329ArgV2R were 14.8- and 2.5-fold lower than Bmax for WT-V2R, respectively. AVP affinity (1/Kd) for WT-V2R and the Ser329Arg-V2R was similar while 1/Kd for Arg104Cys-V2R was increased, cAMP assay revealed that cells expressing p.Arg104Cys-V2R or p.Ser329ArgV2R produced 1.7- and 6.8-fold lower amounts of cAMP compared with WT-V2R, respectively. In conclusion, ligand binding and signal transduction capability are dependent on localization of the amino acid variation. Striking divergences at the level of receptor functionality may thus underlie similar clinical phenotypes in CNDI. [ABSTRACT FROM AUTHOR]

Background:Little is known of vitamin D concentration in cerebrospinal fluid (CSF) in Alzheimer´s disease (AD) and its relation with CSF acetylcholinesterase (AChE) activity, a marker of cholinergic function. Methods:A cross-sectional study of 52 consecutive patients under primary evaluation of cognitive impairment and 17 healthy controls. The patients had AD dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n = 28), other dementias (n = 12), and stable MCI (SMCI, n = 12). We determined serum and CSF concentrations of calcium, parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), and CSF activities of AChE and butyrylcholinesterase (BuChE). Findings:CSF 25OHD level was reduced in AD patients (P < 0.05), and CSF AChE activity was decreased both in patients with AD (P < 0.05) and other dementias (P < 0.01) compared to healthy controls. None of the measured variables differed between BuChE K-variant genotypes whereas the participants that were homozygous in terms of the apolipoprotein E (APOE) ε4 allele had decreased CSF AChE activity compared to subjects lacking the APOE ε4 allele (P = 0.01). In AD patients (n=28), CSF AChE activity correlated positively with CSF levels of total tau (T-tau) (r = 0.44, P < 0.05) and phosphorylated tau protein (P-tau) (r = 0.50, P < 0.01), but CSF activities of AChE or BuChE did not correlate with serum or CSF levels of 25OHD. Conclusions:In this pilot study, both CSF 25OHD level and CSF AChE activity were reduced in AD patients. However, the lack of correlations between 25OHD levels and CSF activities of AChE or BuChE might suggest different mechanisms of action, which could have implications for treatment trials. [ABSTRACT FROM AUTHOR]

Fabry disease (FD) is an X-chromosomal disorder caused by mutations in the GLA gene encoding the lysosomal enzyme α-galactosidase A. We performed mutation screening on a cohort of 121 patients including 84 male and 37 female index cases and identified a total of 90 different mutations, 34 of which are reported for the first time here. Both point mutations (74.4%) and 'short length' rearrangements (25.6%) were found, including missense (54.4%), nonsense (14.4%), and splice site point mutations (5.6%), deletions (17.8%) or insertions/duplications (5.6%) of a few nucleotides, and complex rearrangements including larger deletions (2.2%). GLA mutations were identified in 82 (97.6%) of the 84 unrelated male patients. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The neuropeptides substance P, orexin A (hypocretin-1) and neurotensin are signaling molecules that influence brain activity. We examined their cerebrospinal fluid (CSF) levels in a study population consisting of Alzheimer's disease (AD) dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up ( n = 32), stable MCI (SMCI, n = 13), other dementias ( n = 15), and healthy controls ( n = 20). CSF substance P level was increased in AD patients compared to patients with other dementias and healthy controls ( P < 0.05 and P < 0.01, respectively). Patients with other dementia or SMCI had lower CSF orexin A level than AD patients (both P < 0.05) and marginally lower level than healthy controls (both P = 0.05). CSF neurotensin level was similar in all groups. In the total study population ( n = 80), CSF substance P level correlated positively with CSF levels of T-tau and P-tau, and in AD patients ( n = 32), CSF substance P level correlated positively with CSF A β1–42 level. In conclusion, CSF substance P level was elevated in AD patients and correlated with CSF A β1–42 level, a well established marker of senile plaque pathology. The role of low CSF orexin A level in other dementias or SMCI needs to be explored in further studies. [ABSTRACT FROM AUTHOR]

Objective: Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is characterized by severe polyuria and polydipsia and is caused by variations in the gene encoding the AVP prohormone. This study aimed to ascertain a correct diagnosis, to identify the underlying genetic cause of adFNDI in a Swedish family, and to test the hypothesis that the identified synonymous exonic variant in the AVP gene (c.324G>A) causes missplicing and endoplasmic reticulum (ER) retention of the prohormone., Design/patients: Three affected family members were admitted for fluid deprivation test and dDAVP (1-deamino-8-d-arginine-vasopressin) challenge test. Direct sequencing of the AVP gene was performed in the affected subjects, and genotyping of the identified variant was performed in family members. The variant was examined by expression of AVP minigenes containing the entire coding regions as well as intron 2 of AVP., Methods/results: Clinical tests revealed significant phenotypical variation with both complete and partial adFNDI phenotype. DNA analysis revealed a synonymous c.324G>A substitution in one allele of the AVP gene in affected family members only. Cellular studies revealed both normally spliced and misspliced pre-mRNA in cells transfected with the AVP c.324G>A minigene. Confocal laser scanning microscopy showed collective localization of the variant prohormone to ER and vesicular structures at the tip of cellular processes., Conclusion: We identified a synonymous variant affecting the second nucleotide of exon 3 in the AVP gene (c.324G>A) in a family in which adFNDI segregates. Notably, we showed that this variant causes partial missplicing of pre-mRNA, resulting in accumulation of the variant prohormone in ER. Our study suggests that even a small amount of aberrant mRNA might be sufficient to disturb cellular function, resulting in adFNDI., (© 2018 S. Karger AG, Basel.)

The role of biomarkers in neurodegenerative diseases has been emphasized by recent research. Future clinical demands for identifying diseases at an early stage may render them essential. The aim of this pilot study was to test the analytical performance of two multiplex assays of cerebral markers on a well-defined clinical material consisting of patients with various neurodegenerative diseases. We measured 10 analytes in plasma and cerebrospinal fluid (CSF) from 60 patients suffering from Alzheimer's disease (AD), vascular dementia, frontotemporal dementia, dementia with Lewy bodies, or mild cognitive impairment, as well as 20 cognitively healthy controls. We used the Randox biochip-based Evidence Investigator™ system to measure the analytes. We found it possible to measure most analytes in both plasma and CSF, and there were some interesting differences between the diagnostic groups, although with large overlaps. CSF heart-type fatty acid-binding protein was increased in AD. Glial fibrillary acidic protein and neutrophil gelatinase-associated lipocalin in CSF and D-dimer in plasma were elevated in patients with cerebrovascular disease. A multivariate statistical analysis revealed that the pattern of analytes could help to differentiate the conditions, although more studies are required to verify this.

Purpose: We investigated the bone mineral status in patients with untreated Fabry disease (FD)., Methods: Descriptive, cross-sectional study in 53 patients with FD investigating bone mineral density (BMD)/content (dual energy x-ray absorptiometry scan), bone metabolism (parathyroid hormone, osteocalcin, and insulin-like growth factor I), and renal function (ethylene diamine tetraacetic acid clearance)., Results: Mean BMD z score at the lumbar spine and femoral neck were -0.05 +/- 1.46 SD and -0.37 +/- 1.02 SD, respectively. Approximately 50% had osteopenia in the hip or lumbar spine and additionally four had osteoporosis. Multivariate analysis including body weight, impaired renal function, and genotype overall explained 48% of the variance in lumbar spine BMD (P < 0.001), whereas body weight, impaired renal function, and menopausal status in the female population accounted for more than 50% of the variation in BMD of both the lumbar spine and femoral neck (both P < 0.001). Twenty percent of patients had hyperparathyroidism. Although the level of parathyroid hormone was significantly associated with impaired renal function, osteocalcin levels were significantly higher in patients with lumbar spine osteopenia or osteoporosis than in those with normal BMD., Conclusions: Osteopenia was present in approximately 50% of patients with untreated FD. Whether BMD and bone metabolism will improve after enzyme replacement therapy remains to be established.