645 research outputs found
Evidence for a GABAergic system in rodent and human testis: Local GABA production and GABA receptors
No full textThe major neurotransmitter of the central nervous system, gamma-aminobutyric acid (GABA), exerts its actions through GABA(A), GABA(B) and GABA(C) receptors. GABA and GABA receptors are, however, also present in several non-neural tissues, including the endocrine organs pituitary, pancreas and testis. In the case of the rat testis, GABA appears to be linked to the regulation of steroid synthesis by Leydig cells via GABA(A) receptors, but neither testicular sources of GABA, nor the precise nature of testicular GABA receptors are fully known. We examined these points in rat, mouse, hamster and human testicular samples. RT-PCR followed by sequencing showed that the GABA-synthesizing enzymes glutamate decarboxylase (GAD) 65 and/or GAD67, as well as the vesicular GABA transporter vesicular inhibitory amino acid transporter (VIAAT/VGAT) are expressed. Testicular GAD in the rat was shown to be functionally active by using a GAD assay, and Western blot analysis confirmed the presence of GAD65 and GAD67. Interstitial cells, most of which are Leydig cells according to their location and morphological characteristics, showed positive immunoreaction for GAD and VIAAT/VGAT proteins. In addition, several GABA(A) receptor subunits (alpha1-3, beta1-3, gamma1-3), as well as GABAB receptor subunits R1 and R2, were detected by RT-PCR. Western blot analysis confirmed the results for GABA(A) receptor subunits beta2/3 in the rat, and immunohistochemistry identified interstitial Leydig cells to possess immunoreactive GABA(A) receptor subunits beta2/3 and alpha1. The presence of GABA(A) receptor subunit alpha1 mRNA in interstitial cells of the rat testis was further shown after laser microdissection followed by RT-PCR analysis. In summary, these results describe molecular details of the components of an intratesticular GABAergic system expressed in the endocrine compartment of rodent and human testes. While the physiological significance of this peripheral neuroendocrine system conserved throughout species remains to be elucidated, its mere presence in humans suggests the possibility that clinically used drugs might be able to interfere with testicular function. Copyright (C) 2003 S. Karger AG, Basel
Spin susceptibility and electron-phonon coupling of two-dimensional materials by range-separated hybrid density functionals: Case study of LixZrNCl
No full textWe investigate the capability of density functional theory (DFT) to appropriately describe the spin susceptibility, chi(s), and the intervalley electron-phonon coupling in LixZrNCl. At low doping, LixZrNCl behaves as a two-dimensional two-valley electron gas, with parabolic bands. In such a system, chi(s) increases with decreasing doping because of the electron-electron interaction. We show that DFT with local functionals (LDA/GGA) is not capable of reproducing this behavior. The use of exact exchange in Hartree-Fock (HF) or in DFT hybrid functionals enhances chi(s). HF, B3LYP, and PBE0 approaches overestimate chi(s), whereas the range-separated HSE06 functional leads to results similar to those obtained in the random phase approximation (RPA) applied to a two-valley two-spin electron gas. Within HF, LixZrNCl is even unstable towards a ferromagnetic state for x < 0.16. The intervalley phonons induce an imbalance in the valley occupation that can be viewed as the effect of a pseudomagnetic field. Thus, similarly to what happens for chi(s), the electron-phonon coupling of intervalley phonons is enhanced by the electron-electron interaction. Only hybrid DFT functionals capture such an enhancement and the HSE06 functional reproduces the RPA results presented in M. Calandra et al. [Phys. Rev. Lett. 114, 077001 (2015)]. These results imply that the description of the susceptibility and electron-phonon coupling with a range-separated hybrid functional would be important also in other two-dimensional weakly doped semiconductors, such as transition-metal dichalcogenides and graphene
Familial Hypobetalipoproteinemia Due to a Novel Mutation of Apolipoprotein B Gene " - Horm Res 2004;
No full textSince in most of the introns of the human gene A is present in this position it is likely that the presence of a G in this position, like in our patient, disrupts the splicing process.This hypothesis is supported by the observation that proband’s sister who has also hypobetalipoproteinemia was carrier of the same mutation in intron 8. This mutation has not yet been found in normal subjects and in more than 30 FHBL individuals investigated by our group.In FHBL the variability in symptoms was related to the length of the truncated apoB and its ability to form chylomicrons and absorb fat-soluble vitamins and essential fatty acids rather than the levels of LDL-C). Our patient belongs to our series of “symptomatic” heterozygous FHBL subjects with no truncated apoBs detectable in plasma. This finding raises the question as to whether, in a specific FHBL patient/pedegree, hypobetalipoproteinemia is due to mutation in the APOB gene or in other genes (yet to be identified) affecting apoB metabolism. Probably, hypobetalipoproteinemia explains the presence of liver steatosis already at this age, even if it cannot be excluded that obesity should play a role in this alteration
Absence of apolipoprotein B-48 in the chick, Gallus domesticus
No full textThis study was designed to investigate: a) whether multiple forms of apoB are present in chick plasma lipoproteins; and b) which forms of apoB are produced in vitro by liver and intestine at various stages of pre- and post-natal development. Plasma lipoproteins of d less than 1.019 g/ml, isolated from fasted and nonfasted chicks, contained exclusively the high molecular weight apoB form (apoB-100) that comigrated with human and rat apoB-100 on SDS-PAGE gel. No apoB-48 was detected either in overloaded Coomassie blue-stained gels or after immunoblotting. ApoB-100 but no apoB-48 was found in portomicrons, the triglyceride-rich lipoproteins equivalent to chylomicrons, that in the chick are transported via the porto-mesenteric venous system. To ascertain whether a minute amount of apoB-48 was present in chick plasma, [35S]methionine was injected intraduodenally and the 35S-labeled d less than 1.019 g/ml plasma lipoproteins were isolated 45 min later from the systemic and the porto-mesenteric circulation. Only apoB-100 was found to be labeled in these lipoproteins. Cholesterol feeding did not induce the appearance of apoB-48 in plasma despite a marked accumulation of cholesterol-rich d less than 1.040 g/ml lipoproteins in the plasma. In vitro synthesis of apoB forms was studied in liver and intestinal slices isolated from chick embryos (8 and 5 days before hatching), newly hatched chicks (2 and 7 days after hatching), and young chicks (21 days old) that were incubated in the presence of [35S]methionine. At each stage of development, liver slices secreted predominantly apoB-100. Intestinal slices of newly hatched and young chicks secreted two forms of apoB: apoB-100 and an additional form with an electrophoretic mobility similar to rat plasma apoB-95. No apoB-48 was synthesized or secreted by the intestine. Our results indicate that the absence of apoB-48 in chick plasma reflects the lack of synthesis of this peptide in the intestine. It is conceivable that in chick intestine the recently described molecular mechanism responsible for the co/posttranscriptional modification of apoB mRNA leading to the formation of apoB-48 is lacking or defective
La ricerca geografica come strategia di resilienza: esperienze di partecipazione in contesto post-disastro
No full textL’obiettivo di questo contributo è di mostrare come nell’esperienza sul campo di un gruppo di lavoro del Dipartimento di Scienze Umane (DSU) dell’Università dell’Aquila la ricerca geografica post-sisma abbia di fatto rappresentato una strategia di resilienza in primis per i ricercatori e gli studenti impegnati nell’attività di indagine, ma anche per i cittadini coinvolti nel processo conoscitivo e, in qualche modo, per la componente politico-istituzionale comunale. Sarà illustrata l’attività di ricerca condotta, all’interfaccia tra scienza, società e politica, dal gruppo di lavoro del Laboratorio Cartolab (DSU), insieme a studenti e cittadini. A partire dallo stato dell’arte, soprattutto in ambito geografico, sul concetto di resi-lienza, si espliciteranno i presupposti teorico-concettuali e metodologici della ricerca per poi entrare nel merito dei tempi, dei modi e dei principali risultati di quella che nel frattempo sarà stata definita una ricerca-azione partecipativa/partecipante
A study of fatty liver disease and plasma lipoproteins in a kindred with familial hypobetalipoproteinemia due to a novel truncated form of apolipoprotein B (apo B-54.5)
No full textBACKGROUND/AIMS: Familial hypobetalipoproteinemia (FHBL) is a co-dominant disorder characterized by reduced plasma levels of low-density lipoproteins. It can be caused by mutations in the gene encoding apolipoprotein B-100 (apo B), leading to the formation of truncated apo Bs which have a reduced capacity to export lipids from the hepatocytes as lipoprotein constituents. Case reports suggest the occurrence of liver disease in FHBL, but there are no studies of liver involvement in FHBL with defined apo B gene mutations. The presence of fatty liver disease was investigated in a large FHBL kindred. METHODS: Plasma lipoprotein and apolipoprotein analysis, liver function tests, and apo B gene sequence were performed in 16 members of a FHBL kindred. The presence of fatty liver was assessed by ultrasound and computed tomography scanning. RESULTS: The proband, a non-obese heavy drinker male with hypobetalipoproteinemia, had steatohepatitis with fibrosis. He was heterozygous for a novel non-sense mutation of apo B gene producing a truncated apo B of 2745 amino acids (designated apo B-54.5, having half the size of normal apo B-100). Seven other members of his kindred carried apo B-54.5. Although all of them were hypolipidemic, their lipid levels showed a large inter-individual variability not accounted for by polymorphisms of genes involved in apo B metabolism. Four carriers (two heavy drinkers and two teetotallers), irrespective of their plasma lipid levels, had ultrasonographic evidence of fatty liver. In the other four carriers no evidence of fatty liver was found. CONCLUSIONS: In this kindred apo B-54.5 predisposes to fatty liver, which however may require some additional factors to become clinically relevant
Field-assisted paper spray mass spectrometry for the quantitative evaluation of imatinib levels in plasma
No full textDrug levels in patients' bloodstreams vary among individuals and consequently therapeutic drug monitoring (TDM) is fundamental to controlling the effective therapeutic range. For TDM purposes, different analytical approaches have been used, mainly based on immunoassay, liquid chromatography-ultraviolet, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. More recently a matrix-assisted laser desorption/ionisation method has been proposed for the determination of irinotecan levels in the plasma of subjects under therapy and this method has been cross-validated by comparison with data achieved by LC-MS/MS. However, to reach an effective point-of-care monitoring of plasma drug concentrations, a TDM platform technology for fast, accurate, low-cost assays is required. In this frame, recently the use of paper spray mass spectrometry, which is becoming a popular and widely employed MS method, has been proposed. In this paper we report the results obtained by the development of a paper spray-based method for quantitative analysis in plasma samples of imatinib, a new generation of anticancer drug. Preliminary experiments showed that poor sensitivity, reproducibility and linear response were obtained by the "classical" paper spray set-up. In order to achieve better results, it was thought of interest to operate in presence of a higher and more homogeneous electrical field. For this aim, a stainless steel needle connected with the high voltage power supply was mounted below the paper triangle. Furthermore, in order to obtain valid quantitative data, we analysed the role of the different equilibria participating to the phenomena occurring in paper spray experiments, depending either on instrumental parameters or on the chemical nature of analyte and solvents. A calibration curve was obtained by spiking plasma samples containing different amounts of imatinib (1) with known amounts of deuterated imatinib (1d3) as internal standard, with molar ratios [1]/[1d3] in the range 0.00-2.00. A quite good linearity was obtained (R2 = 0.975) and some experiments performed on spiked plasma samples with known amounts of 1 confirmed the validity of this method
Hypobetalipoproteinemia with an apparently recessive inheritance due to a de novo mutation of apolipoprotein B
No full textFamilial hypobetalipoproteinemia (FHBL) is a co-dominant disorder either linked or not linked to apolipoprotein (apo) B gene. Abetalipoproteinemia (ABL) is a recessive disorder due to mutations of microsomal triglyceride transfer protein (MTP) gene. We investigated a patient with apparently recessive hypobetalipoproteinemia consistent with symptomatic heterozygous FHBL or a mild form of ABL. The proband had fatty liver associated with LDL-cholesterol (LDL-C) and apo B levels <5th percentile but no truncated apo B forms detectable in plasma. MTP gene sequence revealed that he was a carrier of the I128T polymorphism and an unreported amino acid substitution (V168I) unlikely to be the cause of hypobetalipoproteinemia. Apo B gene sequence showed that he was heterozygous for two single base substitutions in exon 9 and 22 resulting in a nonsense (Q294X) and a missense (R1101H) mutation, respectively. Neither of his parents carried the Q294X; his father and paternal grandmother carried the R 110 1 H mutation. Analysis of polymorphic genetic markers excluded non-paternity. In conclusion, the proband has a de novo mutation of apo B gene resulting in a short truncated apo B form (apo B-6.46). Sporadic cases of FHBL with an apparently recessive transmission may be caused by de novo mutations of apo B gene
The history of Autosomal Recessive Hypercholesterolemia (ARH): from clinical observation to gene identification
No full textThe most frequent form of monogenic hypercholesterolemia, also known as Familial Hypercholesterolemia (FH), is characterized by plasma accumulation of cholesterol transported in Low Density Lipoproteins (LDLs). FH has a co-dominant transmission with a gene-dosage effect. FH heterozygotes have levels of plasma LDL-cholesterol (LDL-C) twice normal and present xanthomas and coronary heart disease (CHD) in adulthood. In rare FH homozygotes plasma LDL-C level is four times normal, while xanthomas and CHD are present from infancy. Most FH patients are carriers of mutations of the LDL receptor (LDLR); a minority of them carry either mutations in the Apolipoprotein B (ApoB), the protein constituent of LDLs which is the ligand for LDLR, or gain of function mutations of PCSK9, the protein responsible for the intracellular degradation of the LDLR. From 1970 to the mid 90s some publications described children with the clinical features of homozygous FH, who were born from normocholesterolemic parents, strongly suggesting a recessive transmission of FH. In these patients the involvement of LDLR and APOB genes was excluded. Interestingly, several patients were identified in the island of Sardinia (Italy), whose population has a peculiar genetic background due to geographical isolation. In this review, starting from the early descriptions of patients with putative recessive hypercholesterolemia, we highlight the milestones that led to the identification of a novel gene involved in LDL metabolism and the characterization of its encoded protein. The latter turned out to be an adaptor protein required for the LDLR-mediated endocytosis of LDLs in hepatocytes. The loss of function of this protein is the cause of Autosomal Recessive Hypercholesterolemia (ARH
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