A genome-wide association study reveals variants in ARL15 that influence adiponectin levels

The adipocyte-derived protein adiponectin is highly heritable and inversely associated with risk of type 2 diabetes mellitus (T2D) and coronary heart disease (CHD). We meta-analyzed 3 genome-wide association studies for circulating adiponectin levels (n = 8,531) and sought validation of the lead single nucleotide polymorphisms (SNPs) in 5 additional cohorts (n = 6,202). Five SNPs were genome-wide significant in their relationship with adiponectin (P< or =5x10(-8)). We then tested whether these 5 SNPs were associated with risk of T2D and CHD using a Bonferroni-corrected threshold of P< or =0.011 to declare statistical significance for these disease associations. SNPs at the adiponectin-encoding ADIPOQ locus demonstrated the strongest associations with adiponectin levels (P-combined = 9.2x10(-19) for lead SNP, rs266717, n = 14,733). A novel variant in the ARL15 (ADP-ribosylation factor-like 15) gene was associated with lower circulating levels of adiponectin (rs4311394-G, P-combined = 2.9x10(-8), n = 14,733). This same risk allele at ARL15 was also associated with a higher risk of CHD (odds ratio [OR] = 1.12, P = 8.5x10(-6), n = 22,421) more nominally, an increased risk of T2D (OR = 1.11, P = 3.2x10(-3), n = 10,128), and several metabolic traits. Expression studies in humans indicated that ARL15 is well-expressed in skeletal muscle. These findings identify a novel protein, ARL15, which influences circulating adiponectin levels and may impact upon CHD risk.

Hypogonadotropic hypogonadism due to a novel missense mutation in the first extracellular loop of the neurokinin B receptor

CONTEXT

The neurokinin B (NKB) receptor, encoded by TACR3, is widely expressed within the central nervous system, including hypothalamic nuclei involved in regulating GnRH release. We have recently reported two mutations in transmembrane segments of the receptor and a missense mutation in NKB in patients with normosmic isolated hypogonadotropic hypogonadism (nIHH).

PATIENTS AND METHODS

We sequenced the TACR3 gene in a family in which three siblings had nIHH. The novel mutant receptor thus identified was studied in a heterologous expression system using calcium flux as the functional readout.

RESULTS

All affected siblings were homozygous for the His148Leu mutation, in the first extracellular loop of the NKB receptor. The His148Leu mutant receptor exhibited profoundly impaired signaling in response to NKB (EC(50) = 3 +/- 0.1 nm and >5 microm for wild-type and His148Leu, respectively). The location of the mutation in an extracellular part of the receptor led us also to test whether senktide, a synthetic NKB analog, may retain ability to stimulate the mutant receptor. However, the signaling activity of the His148Leu receptor in response to senktide was also severely impaired (EC(50) = 1 +/- 1 nm for wild-type and no significant response of His148Leu to 10 microm).

CONCLUSIONS

Homozygosity for the TACR3 His148Leu mutation leads to failure of sexual maturation in humans, whereas signaling by the mutant receptor in vitro in response to either NKB or senktide is severely impaired. These observations further strengthen the link between NKB, the NKB receptor, and regulation of human reproductive function.

Cholesterol sensor ORP1L contacts the ER protein VAP to control Rab7-RILP-p150 Glued and late endosome positioning

Late endosomes (LEs) have characteristic intracellular distributions determined by their interactions with various motor proteins. Motor proteins associated to the dynactin subunit p150(Glued) bind to LEs via the Rab7 effector Rab7-interacting lysosomal protein (RILP) in association with the oxysterol-binding protein ORP1L. We found that cholesterol levels in LEs are sensed by ORP1L and are lower in peripheral vesicles. Under low cholesterol conditions, ORP1L conformation induces the formation of endoplasmic reticulum (ER)-LE membrane contact sites. At these sites, the ER protein VAP (VAMP [vesicle-associated membrane protein]-associated ER protein) can interact in trans with the Rab7-RILP complex to remove p150(Glued) and associated motors. LEs then move to the microtubule plus end. Under high cholesterol conditions, as in Niemann-Pick type C disease, this process is prevented, and LEs accumulate at the microtubule minus end as the result of dynein motor activity. These data explain how the ER and cholesterol control the association of LEs with motor proteins and their positioning in cells.

[The relations between neurocognition and quality of life in people with schizophrenia]

Neurocognitive deficits constitute an important and significant characteristic of Schizophrenia. Recent investigations tried to establish a causal relationship between neurocognitive deficits and functional outcomes. However, in studies that used quality of life as the primary functional variable, mixed results were found. In some studies associations with neurocognition were strong, but in others, the associations were week or inexistent. The purpose of this study was to identify neurocognitive constructs that seems to be differential predictors of distinct quality of life dimensions. Sample consisted of 37 individuals diagnosed with Schizophrenia. All subjects were assessed with a battery of neurocognitive tests. For the assessment of quality of life we used the WHOQOL--Bref Portuguese Version. We performed correlational analysis and stepwise multiple regression analysis, in order to determine predictive models of quality of life. There were found significant correlations between most of the neurocognitive constructs and quality of life. Predictive models explained 21% to 49% of the variance in the domains of quality of life that we considered. Significant neurocognitive predictors were the following: for the Physical domain, the executive functions; for the Psychological and Social Relations domains, attention and visual-spatial organization; for the Environmental domain, the executive functions and attention. These results highlight the significance of basic neurocognitive functions to the determination of quality of life outcomes in persons with Schizophrenia, especially the functions related to the ability to adapt to changes and to the environmental feedback, the ability to keep focused and attentive, and the aptitude to correctly organize perceptual data.

MHC class II molecules on the move for successful antigen presentation

Major histocompatibility complex class II (MHC II) molecules are targeted to endocytic compartments, known as MIIC, by the invariant chain (Ii) that is degraded upon arrival in these compartments. MHC II acquire antigenic fragments from endocytosed proteins for presentation at the cell surface. In a unique and complex series of reactions, MHC II succeed in exchanging a remaining fragment of Ii for other protein fragments in subdomains of MIIC before transport to the cell surface. Here, the mechanisms regulating loading and intracellular trafficking of MHC II are discussed.

Activation of endosomal dynein motors by stepwise assembly of Rab7-RILP-p150Glued, ORP1L, and the receptor betalll spectrin

The small GTPase Rab7 controls late endocytic transport by the minus end–directed motor protein complex dynein–dynactin, but how it does this is unclear. Rab7-interacting lysosomal protein (RILP) and oxysterol-binding protein–related protein 1L (ORP1L) are two effectors of Rab7. We show that GTP-bound Rab7 simultaneously binds RILP and ORP1L to form a RILP–Rab7–ORP1L complex. RILP interacts directly with the C-terminal 25-kD region of the dynactin projecting arm p150^Glued, which is required for dynein motor recruitment to late endocytic compartments (LEs). Still, p150^Glued recruitment by Rab7–RILP does not suffice to induce dynein-driven minus-end transport of LEs. ORP1L, as well as βIII spectrin, which is the general receptor for dynactin on vesicles, are essential for dynein motor activity. Our results illustrate that the assembly of microtubule motors on endosomes involves a cascade of linked events. First, Rab7 recruits two effectors, RILP and ORP1L, to form a tripartite complex. Next, RILP directly binds to the p150^Glued dynactin subunit to recruit the dynein motor. Finally, the specific dynein motor receptor Rab7–RILP is transferred by ORP1L to βIII spectrin. Dynein will initiate translocation of late endosomes to microtubule minus ends only after interacting with βIII spectrin, which requires the activities of Rab7–RILP and ORP1L.

Rab7 and Rab27a control two motor protein activities involved in melanosomal transport

Melanosomes are lysosome-related organelles that synthesize, store and transport melanin. In epidermal melanocytes, melanosomes mature and are transferred to surrounding keratinocytes, which is essential for skin and coat colour. Mouse coat colour mutants reveal a critical role for the small GTPase Rab27a, which recruits myosin Va through its effector protein melanophilin/Slac2a. Here we have studied how two different Rab GTPases control two motor proteins during subsequent phases in transport of melanosomes. We show that the small GTPase Rab7 mainly associates with early and intermediate stage melanosomes and Rab27a to intermediate and mature melanosomes. Rab27a is found in an active state on mature melanosomes in the tips of the dendrites. The Rab7-Rab7-interacting lysosomal protein-dynein pathway only controls early and intermediate stage melanosomes because the mature melanosomes lack Rab7 and associate with the actin network through Rab27a recruited MyoVa. Thus two Rab proteins regulate two different motor proteins, thereby controlling complementary phases in melanosome biogenesis: Rab7 controls microtubule-mediated transport of early and Rab27a the subsequent actin-dependent transport of mature melanosomes.

A splice variant of RILP induces lysosomal clustering independent of dynein recruitment

The small GTPase Rab7 controls fusion and transport of late endocytic compartments. A critical mediator is the Rab7 effector RILP that recruits the minus-end dynein-dynactin motor complex to these compartments. We identified a natural occurring splice variant of RILP (RILPsv) lacking only 27 amino acids encoded by exon VII. Both variants bind Rab7, prolong its GTP-bound state, and induce clustering of late endocytic compartments. However, RILPsv does not recruit the dynein-dynactin complex, implicating exon VII in motor recruitment. Clustering might still occur via dimerization, since both RILP and RILPsv are able to form hetero- and homo-dimers. Moreover, both effectors compete for Rab7 binding but with different outcome for dynein-dynactin recruitment and transport. Hence, RILPsv provides an extra dimension to the control of vesicle fusion and transport by the small GTPase Rab7.

Cutaneous manifestations of familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy is an autosomal dominant amyloidosis, characterized by the systemic deposition of amyloid with a particular involvement of the peripheral nerves. The disease generally manifests as a severe sensory, motor and autonomic neuropathy. Cardiomyopathy, nephropathy, vitreous opacities and carpal tunnel syndrome may occur in a variable association with the neuropathy. Trophic dermatological lesions are frequent in the more advanced stages of the disease. We examined the skin of 142 patients. The cutaneous manifestations more frequently observed were: xerosis (81.6%), seborrheic dermatitis (21.8%), traumatic and burn lesions (19.7%), acne (18.3%), neurotrophic ulcers (14%) and onychomycosis (10.5%). Among the hepatic transplanted patients (31%), seborrheic dermatitis and acne were the most frequent diagnoses.

Tremor as the first neurological manifestation of Sneddon's syndrome

We report on a 54-year-old woman with Sneddon's syndrome manifested by livedo reticularis, fetal losses, hypertension, and high antinuclear antibody titres. At the age of 42 years she developed tremor of the trunk, limbs, and head only in the standing position that interfered with walking, followed some years later by cognitive decline and a parkinsonian syndrome. T2-weighted brain magnetic resonance imaging showed high signal in cortical areas, basal ganglia, midbrain, and cerebellum.

Plasma cell cheilitis

Plasma cell cheilitis is a rare inflammatory disorder of the lip with a characteristic band-like infiltrate of plasma cells in the upper dermis. Differential diagnosis should consider allergic/irritant contact cheilitis, candidiasis, syphilis, Queyrat's erythroplasia, granulomatous cheilitis, plasmoacanthoma, plasmacytoma, squamous cell carcinoma and exfoliative or factitious cheilitis. We observed plasma cell cheilitis in a 60-year-old Caucasian female who had a partial response to topical steroids and oral griseofulvin.

296LIPIDIC CONTENT IN JERSEY BLASTOCYSTS COMPARED WITH HOLSTEIN AND IVP EMBRYOS

The objective of this study was to compare the ultrastructure of bovine embryos from different breeds and origin in terms of lipid contents. Jersey and Holstein embryos produced in vivo were obtained from superovulated donors by non-surgical method 7 days after AI. Embryos produced in vitro (Holstein cross breed) were obtained from cumulus-oocytes complexes (COC) aspirated from slaughterhouse ovaries. The COC were matured and fertilized in vitro. The zygotes were cultivated in vitro for 7 days in SOFaa media. Embryos produced in vivo (Holstein n=5; Jersey n=5) and in vitro (n=5) classified as blastocyts grade II were fixed in Karnovsky solution immediately after embryo recovery or embryo culture and prepared for microscopic electronic evaluation. Ultrastructure of inner cell mass and trophoblast cells was analyzed. Morphometry on electron microscopy was performed using a point-count method in random samples of electron micrographs of each embryo category. The data were analyzed by chi square test. The volume density occupied by number of lipid droplets was greater in Jersey and in vitro-produced embryos compared with Holstein embryos (24.3%±11.7; 28.4%±19.6 and 9%±6.68, respectively, P&lt;0,05).

[Hospital outcome and short-term follow-up of elderly patients presenting to the emergency unit with congestive heart failure]

PURPOSE

To evaluate the in-hospital (IH) outcome and the short-term follow-up of predominantly elderly patients presenting to an emergency room (ER) with congestive heart failure (CHF).

METHODS

In an 11 month period, 57 patients presenting to the ER with CHF were included. Mean age was 69 +/- 15 years (27 to 94) and 39 (68.4%) were male. CHF diagnosis was based on the Boston criteria. We evaluated IH outcome and prognosis in a mean follow-up of 5.7 +/- 2.7 months (1 to 12). In addition, some mortality predictors and mechanisms of death according on the ACME system were identified.

RESULTS

Eight patients (14%) died in the IH period. Modes of death were circulatory failure (CF) in 7, and peri-operative (PO) in one (aortic valve replacement). During follow-up 9 deaths occurred. Five were due to CF, 2 were sudden and 2 were PO (mitral valve replacement and ventriculectomy). Six-months and 1-year survival rates of the patients who were discharged were 82% and 66%, respectively. Sodium lower than 135 mEq/l (p = 0.004) and female gender (p = 0.038) were independent predictors of mortality.

CONCLUSION

Elderly patients with CHF admitted to the ER have high in-hospital and short-term follow up mortalities. The majority die from CF due to worsening heart failure.

[Coronary artery dissection without acute myocardial infarction]

A 57 year-old-man with acute aortic dissection (DeBakey type I) who developed right coronary artery dissection without acute myocardial infarction. He was successful surgically treated and became asymptomatic.

[Myocardial revascularization in left coronary trunk lesion in patients over 65 years old]

PURPOSE

To study the short and long-term follow-up of patients with left main coronary artery disease (LMCAD) and age over 65 years, by comparing the results with patients under 65 years-old.

METHODS

Twenty-two patients with LMCAD and mean age of 69 +/- 3.5 years (group I) were underwent isolated coronary artery bypass grafting (CABG) and compared to 31 patients with LMCAD, mean age of 54 +/- 7 years (group II), who also underwent isolated CABG. The life-table Kaplan-Meyer method was used to estimate the post-operative survival. The chi-square and Student "t" test were used when necessary.

RESULTS

Despite higher operative mortality in group I (9.1% x 3.2%), the difference was statistically not significant. The operative morbidity was similar in both groups. Actuarial survival at 4 years was 85% in group I and 95% in group II. Actuarial survival free of cardiac events was 69% in group II and 75% in group II.

CONCLUSION

The CABG is well tolerated and had low morbidity and acceptable mortality in old patients with LMCAD. The long-term survival in these patients was very similar to the younger patients.

Immunohistochemical characterisation of probable intravascular haematopoiesis in the vasa rectae of the renal medulla in acute tubular necrosis

Immunohistochemistry was applied to identify the nature of the nucleated cells that accumulate in the vasa rectae of the corticomedullary junction in acute tubular necrosis. In all 6 cases studied, there were intravascular cells that reacted with monoclonal antibodies to erythroblast, macrophages, myeloid cells, T and B lymphocytes and rare megakaryocytes. The findings are consistent with the occurrence of intravascular haematopoiesis in the renal medulla in acute tubular necrosis.

Case report: cyclosporin A-induced neurotoxicity

Acute encephalopathy is a recognized toxic effect of Cyclosporin A (CsA) in organ transplantation recipients. A 16-year-old girl presented with acute encephalopathy 2 weeks after CsA and methylprednisolone medication for idiopathic uveitis. Magnetic resonance imaging showed cortical and white matter occipital changes, which were not visible 2 months later. With expanding indication for CsA use, an increasing number of neurotoxic cases are to be expected.