Release of platelet fibronectin (cold-insoluble globulin) from alpha granules induced by thrombin or collagen; lack of requirement for plasma fibronectin in ADP-induced platelet aggregation

Platelets lysed with Triton X-100 contain 3.44 +/- 1.27 (SD) microgram of fibronectin (cold-insoluble globulin) per 10(9) platelets. Fibronectin was partially released from washed whole platelets by collagen or thrombin, and its release by collagen was inhibited by aspirin. Analysis of subcellular fractions obtained by density-gradient centrifugation of disrupted platelets indicated that fibronectin was contained in the alpha granules. Fibrinogen depleted of fibronectin (less than 2 microgram/mg) supported ADP-induced aggregation as effectively as fibrinogen contaminated with this protein, thus reinforcing the generally held view that fibrinogen itself is the necessary protein cofactor in this reaction.     

Mutation hotspots in the PHKA2 gene in X-linked liver glycogenosis due to phosphorylase kinase deficiency with atypical activity in blood cells (XLG2)

In five cases of X-linked liver glycogenosis subtype 2 (XLG2), we have identified mutations in the gene encoding the liver isoform of the phosphorylase kinase alpha subunit (PHKA2). XLG2 is a rare variant of X- linked phosphorylase kinase (Phk) deficiency of the liver. Whereas in the more common form of X-linked hepatic Phk deficiency, XLG1, the enzyme's activity is decreased both in liver and in blood cells, Phk activity in XLG2 is low in liver but normal or even enhanced in blood cells. Although missense, nonsense and splicesite mutations in the PHKA2 gene were recently identified in several cases of XLG1, no mutations have yet been described for XLG2 and a molecular explanation for the peculiar biochemical phenotype of XLG2 has been lacking. All mutations found in the present study result in non-conservative amino acid replacements of residues that are absolutely conserved between the alpha L, alpha M and beta subunits of Phk [H132P, H132Y, R186H (twice) and D299G]. Strikingly, in two pairs of cases the mutations affect the same codon. These results demonstrate that: (i) XLG2 is caused by mutations in PHKA2 and is therefore allelic with XLG1; and (ii) XLG2 mutations appear to cluster in limited sequence regions or even individual codons.      

SPG7 mutational screening in spastic paraplegia patients supports a dominant effect for some mutations and a pathogenic role for p.A510V

Sánchez‐Ferrero E, Coto E, Beetz C, Gámez J, Corao A, Díaz M, Esteban J, del Castillo E, Moris G, Infante J, Menéndez M, Pascual‐Pascual SI, López de Munaín A, Garcia‐Barcina MJ, Alvarez V on behalf of the Genetics of Spastic Paraplegia study group. SPG7 mutational screening in spastic paraplegia patients supports a dominant effect for some mutations and a pathogenic role for p.A510V. Mutations in the SPG7 gene were initially reported in patients with autosomal recessive hereditary spastic paraplegia (HSP). Recent works suggested a dominant effect for some SPG7 mutations. To characterize the SPG7 mutational spectrum in a large cohort of Spanish HSP patients, we sequenced the whole SPG7 gene in a total of 285 Spastic Paraplegia patients. Large gene rearrangements were also ascertained in some patients. We found a total of 14 SPG7 mutations (12 new) in 14 patients; 2 were large deletions. All the mutation carriers had an adult onset age but only five (35%) had a complicated phenotype. We identified a single mutation in 13 patients. Familial analysis suggested a dominant inheritance for one (p.Leu78*) of these mutations. Carriers of the rare p.A510V variant were significantly more frequent in patients vs healthy controls (3% vs 1%), suggesting a pathogenic role for this SPG7 variant. We reported a high frequency of patients with only one SPG7 mutation, and a putative pathogenic role for the p.A510V variant.     

Minimizing complications during retropubic radical prostatectomy - is ureteral stenting necessary?

Objectives and aims

To avoid damage to the ureters during bladder neck preparation in radical prostatectomy for prostate cancer, it may be helpful to insert ureteral stents temporarily or to intravenously administer indigo carmine dye for enhanced visualisation of ureteric orifices. We evaluated our bladder neck preserving technique at radical prostatectomy with regard to ureteric injuries.

Patients and methods

We analysed 369 consecutive radical prostatectomies operated in our clinic in a bladder neck preserving technique. The following parameters were assessed in this retrospective study: number of prophylactic ureteric stent insertions, application of indigo carmine dye, observed injuries of the ureters by the surgeon, postoperative increase of serum creatinine and postoperative status of kidney ultrasound.

Results

In 7/369 prostatectomies (1.90%) a ureteric stent insertion was performed, indigo carmine was not applied to any patient at all, yet no intraoperative injury of a ureter was observed by a surgeon. No revision was necessary due to a ureteral injury within the observation period of one year after surgery. In 17 patients with preoperative normal creatinine value a pathological value was observed on the first postoperative day (mean 1.4 mg/dl). In these patients no consecutive postrenal acute renal failure was observed, no hydronephrosis was monitored by ultrasound and no further intervention was necessary.

Conclusions

Bladder neck preserving operation technique does not implicate the need of prophylactic ureteric stent insertions and has no higher incidence of ureteric injuries.     

腹主动脉瘤病因新探讨

目的 证实家族性因素和遗传性因素在腹主动脉瘤（ａｂｄｏｍｉｎａｌ ａｏｒｔｉｃ ａｎｅｕｒｙｓｍ,ＡＡＡ）发病中的作用。方法 ３０８例澳大利亚欧洲腹主动脉瘤病人和１１０例健康对照组以及男女各４０例的新生儿对照组。对动脉壁四种重要结构蛋白基因进行等位因基分析。等位基因频率分析采用Ｓｈａｍ ａｎｄ Ｃｕｒｔｉｓ方法。结果 ５０例ＡＡＡ病人至少有一例直系亲属患者ＡＡＡ。在５３９例存活的同代亲属中,１４例     

The ancestral gene for transcribed, low-copy repeats in the Prader- Willi/Angelman region encodes a large protein implicated in protein trafficking, which is deficient in mice with neuromuscular and spermiogenic abnormalities

Transcribed, low-copy repeat elements are associated with the breakpoint regions of common deletions in Prader-Willi and Angelman syndromes. We report here the identification of the ancestral gene ( HERC2 ) and a family of duplicated, truncated copies that comprise these low-copy repeats. This gene encodes a highly conserved giant protein, HERC2, that is distantly related to p532 (HERC1), a guanine nucleotide exchange factor (GEF) implicated in vesicular trafficking. The mouse genome contains a single Herc2 locus, located in the jdf2 (juvenile development and fertility-2) interval of chromosome 7C. We have identified single nucleotide splice junction mutations in Herc2 in three independent N-ethyl-N-nitrosourea-induced jdf2 mutant alleles, each leading to exon skipping with premature termination of translation and/or deletion of conserved amino acids. Therefore, mutations in Herc2 lead to the neuromuscular secretory vesicle and sperm acrosome defects, other developmental abnormalities and juvenile lethality of jdf2 mice. Combined, these findings suggest that HERC2 is an important gene encoding a GEF involved in protein trafficking and degradation pathways in the cell.      

Loss-of-function mutations in the immunoglobulin superfamily member 1 gene (IGSF1) cause a novel,X-linked syndrome of central hypothyroidism and testicular enlargement

BackgroundCongenital central hypothyroidism occurs either as isolated thyroid-stimulating hormone (TSH) deficiency or in conjunction with other pituitary hormone deficits. Undetected central hypothyroidism is associated with developmental delay in children and adverse cardiometabolic sequelae in adults. Hitherto, mutations in the thyrotropin-releasing hormone receptor gene (TRHR) or the TSHb subunit gene (TSHB) are the only known causes of isolated TSH deficiency.MethodsUsing whole exome and candidate gene sequencing, we have studied 11 unrelated families with males exhibiting isolated TSH deficiency, testicular enlargement, and variably low serum prolactin levels.FindingsWe have identified eight distinct mutations and two whole gene deletions disrupting the X-linked immunoglobulin superfamily member 1 gene (IGSF1) in affected males. IGSF1 encodes a pituitary-enriched plasma membrane glycoprotein; disease-associated mutations block trafficking of IGSF1 from the endoplasmic reticulum to the membrane, consistent with loss-of-protein function. Adult male IGSF1 null mice exhibit central hypothyroidism with decreased pituitary TSH content and circulating T3 levels; TSH secretion in response to TRH is blunted and pituitary TRHR mRNA levels are decreased, suggesting that impaired TRH signalling may provide the basis for hypothyroidism.InterpretationOur observations delineate a novel X-linked syndrome in which loss-of-function mutations in IGSF1 cause central hypothyroidism, testicular enlargement, and variable prolactin deficiency, and identify a previously unsuspected role for IGSF1 in hypothalamic-pituitary control of thyroid and testicular function. Variable biochemical penetrance in these families highlights the importance of genetic ascertainment in this syndrome, so that asymptomatic affected individuals can benefit from early initiation of thyroxine treatment.FundingWellcome Trust and National Institute for Health Research Biomedical Research Centre.