Ramification of the portal vein at the porta hepatis in humans

The ramification of the portal vein at the porta hepatis was studied by anatomic dissection performed in 32 formalin fixed human livers. In all the specimens there were branches which ran towards the caudate lobe, arising from the portal vein and either from the left or the right portal branches. Tri-and quadrifurcation of the portal vein was observed. In 5 cases (16%) there were branches arising from left portal branch or portal vein and directed anteriorly to the quadrate lobe or to the region of the gall-bladder sulcus. These branches ranged from 1.0 to 6.0 mm in diameter. The portal caudate branches were divided into 3 groups.Group 1: Branches to the papillary process; 1 or 2 branches in 26 cases (82%), 3 or 5 branches in 3 cases (9%) and no branches in 3 cases (9%);     

Charcot-Marie-Tooth phenotype produced by a duplicated PMP22 gene as part of a 17P trisomy-translocation to the X chromosome

The Charcot-Mane-Tooth disease type 1A (CMTlA) phenotype is most often associated with a 1.5 megabase (mb), tandem duplication of chromosome 17 band p12 (17˜12). The prevailing hypothesis is that the demyelinating neuropathy results from a dosage effect of the peripheral myelin protein gene PMP22 which is included within this duplication. We present a patient with clinical and electrophysiological features ofCMTlA in whom an extra PMP22 gene resulted from a rare unbalanced translocation of 17p to the X chromosome. This finding further supports the hypothesis of gene dosage as the basis for CMTlA. More-over, this case highlights the importance of fluorescence in siiu hybridization (FISH) as an alternative molecular technique in the diagnosis of CMTlA.     

Inhibition of the Mixed Lymphocyte Culture Response by Antibody Following Successful Human Renal Transplantation

Immunoglobulin G, appearing after several months in the serum of a recipient of a successful kidney transplant from a closely matched sibling donor, was demonstrated to progressively inhibit unidirectional mixed lymphocyte cultures when donor lymphocytes were used either in responding or stimulating cell populations. The active recipient IgG had no effect in cultures in which donor cells were not used, nor did IgG obtained from other individuals show nonspecific inhibitory effects on cultures containing donor cells. It is suggested that the MLC inhibitory immunoglobulin may serve an immunoregulatory function after renal transplantation.     

Life expectancy in British Marfan syndrome populations

A total of 206 patients with Marfan syndrome were ascertained throughout genetic clinics in Wales and Scotland during the period 1970–1990. There were 45 deaths representing 22% of the cohort. Mean age at death was 45.3 ± 16.5 years. 50% median cumulative survival in the total cohort (n = 206) was 53 years for males and 72 years for females. Multivariate analysis confirmed severity as the best independent indicator of survival. These findings and survival curves will assist in the counselling of British families and individuals with Marfan syndrome.     

The GAP-related domain of tuberin, the product of the TSC2 gene, is a target for missense mutations in tuberous sclerosis

Tuberous sclerosis is an autosomal dominant trait in which the dysregulation of cellular proliferation and differentiation results in the development of hamartomatous growths in many organs. The TSC2 gene is one of two genes determining tuberous sclerosis. Inactivating germline mutations of TSC2 in patients with tuberous sclerosis and somatic loss of heterozygosity at the TSC2 locus in the associated hamartomas indicate that TSC2 functions as a tumour suppressor gene and that loss of function is critical to expression of the tuberous sclerosis phenotype. The TSC2 product, tuberin, has a region of homology with the GTPase activating protein rap1GAP and stimulates the GTPase activity of rap1a and rab5a in vitro. Here we show that the region of homology between tuberin and human rap1GAP and the murine GAP mSpa1 is more extensive than previously reported and spans approximately 160 amino acid residues encoded within exons 34-38 of the TSC2 gene. Single strand conformation polymorphism analysis of these exons in 173 unrelated patients with tuberous sclerosis and direct sequencing of variant conformers together with study of additional family members enabled characterisation of disease associated mutations in 14 cases. Missense mutations, which occurred in exons 36, 37 and 38 were identified in eight cases, four of whom shared the same recurrent change P1675L. Each of the five different missense mutations identified was shown to occur de novo in at least one sporadic case of tuberous sclerosis. The high proportion of missense mutations detected in the region of the TSC2 gene encoding the GAP-related domain supports its key role in the regulation of cellular growth.