TDP-43-M323K causes abnormal brain development and progressive cognitive and motor deficits associated with mislocalised and increased levels of TDP-43.

TDP-43 pathology is found in several neurodegenerative disorders, collectively referred to as "TDP-43 proteinopathies". Aggregates of TDP-43 are present in the brains and spinal cords of >97% of amyotrophic lateral sclerosis (ALS), and in brains of ∼50% of frontotemporal dementia (FTD) patients. While mutations in the TDP-43 gene (TARDBP) are usually associated with ALS, many clinical reports have linked these mutations to cognitive impairments and/or FTD, but also to other neurodegenerative disorders including Parkinsonism (PD) or progressive supranuclear palsy (PSP). TDP-43 is a ubiquitously expressed, highly conserved RNA-binding protein that is involved in many cellular processes, mainly RNA metabolism. To investigate systemic pathological mechanisms in TDP-43 proteinopathies, aiming to capture the pleiotropic effects of TDP-43 mutations, we have further characterised a mouse model carrying a point mutation (M323K) within the endogenous Tardbp gene. Homozygous mutant mice developed cognitive and behavioural deficits as early as 3 months of age. This was coupled with significant brain structural abnormalities, mainly in the cortex, hippocampus, and white matter fibres, together with progressive cortical interneuron degeneration and neuroinflammation. At the motor level, progressive phenotypes appeared around 6 months of age. Thus, cognitive phenotypes appeared to be of a developmental origin with a mild associated progressive neurodegeneration, while the motor and neuromuscular phenotypes seemed neurodegenerative, underlined by a progressive loss of upper and lower motor neurons as well as distal denervation. This is accompanied by progressive elevated TDP-43 protein and mRNA levels in cortex and spinal cord of homozygous mutant mice from 3 months of age, together with increased cytoplasmic TDP-43 mislocalisation in cortex, hippocampus, hypothalamus, and spinal cord at 12 months of age. In conclusion, we find that Tardbp M323K homozygous mutant mice model many aspects of human TDP-43 proteinopathies, evidencing a dual role for TDP-43 in brain morphogenesis as well as in the maintenance of the motor system, making them an ideal in vivo model system to study the complex biology of TDP-43.

Uterine artery embolisation for uterine fibroids: Our experience at a tertiary care service hospital.

BACKGROUND: Uterine artery embolisation (UAE) has evolved as a minimally invasive and effective alternative, treatment modality for women with symptomatic fibroids. We discuss our initial experience of UAE in the management of symptomatic fibroids. METHODS: Twenty five symptomatic patients of uterine fibroids were treated with UAE by selectively cannulating and injecting poly vinyl alcohol particles into the uterine arteries. Post treatment follow up was done at 2 and 6 months respectively. RESULTS: Pre-treatment, the sizes of fibroids were between 3.9 and 10.9 cm (mean 7.4) on ultrasonography. Of the total 25 patients, 49 uterine arteries were embolised with a technical success rate of 98%. Menorrhagia persisted in 7 patients, dysmenorrhea in 4 patients and pressure symptoms in 2 patients respectively in follow up study of six months which corresponds to a reduction in symptoms by 68% for menorrhagia, 71% for dysmenorhoea and 75% for those with pressure symptoms respectively. At 2 months follow-up post embolisation, the mean diameter of the fibroid was 4.03 cm (range 2-5.2 cm) and at 6 months 3.2 cm (range 1.3-4.1 cm), corresponding to size reduction of 45.5% and 57%, respectively. Follow up with ultrasonography at 2 and 6 months period showed successful fibroid reduction in 24 patients with corresponding reduction in the symptomatology. One patient remained symptomatic with increase in fibroid size and had to undergo hysterectomy. CONCLUSION: Uterine artery embolisation can be considered as an alternative to hysterectomy in appropriately selected symptomatic patients of uterine fibroids.

Virtual Scopy with Multidetector CT.

Virtual scopy is a computerized, non-invasive technique used in simulating views provided by a fiber optic endoscope. Multidetector CT (MDCT) enhances the technique of Virtual scopy, by its z-axis resolution, faster data acquisition and improved 3D-image quality. The common application included Virtual Colonoscopy, Bronchoscopy, Gastroscopy, Angioscopy, Labyrinthoscopy, Thoracoscopy and Stentoscopy. Of the 45 Virtual scopies referred to Radiology Department at INHS Asvini, the single largest application was Virtual Angioscopy followed by Stentoscopy and the smallest was evaluation of larynx, labyrinth, colon and mediastinum accounting for 3 each. Endoscopy data and histopathological diagnosis was available in 17 patients, who underwent Virtual studies of larynx, airway, stomach, mediastinum and colon.

Biomarkers specific to densely-ionising (high LET) radiations.

There have been several suggestions of biomarkers that are specific to high LET radiation. Such a biomarker could significantly increase the power of epidemiological studies of individuals exposed to densely-ionising radiations such as alpha particles (e.g. radon, plutonium workers, individuals exposed to depleted uranium) or neutrons (e.g. radiation workers, airline personnel. We discuss here a potentially powerful high LET biomarker (the H value) which is the ratio of induced inter-chromosomal aberrations to intra-arm aberrations. Both theoretical and experimental studies have suggested that this ratio should differ by a factor of about three between high LET radiation and any other likely clastogen, and will yield more discrimination than the previously suggested F value (ratio of inter-chromosomal aberrations to intra-chromosomal inter-arm aberrations). Evidence of the long-term stability of such chromosomal biomarkers has also been generated. Because these stable intra-arm anld inter-chromosomal aberrations are (1) frequent and (2) measurable at long times after exposure, this H value appears to be a practical biomarker of high LET exposure, and several in vitro studies have confirmed the approach for unstable aberrations. The approach is currently being tested in a population of Russian radiation workers exposed several decades ago to high- or low LET radiation.

Cloning of murine NKG2A, B and C: second family of C-type lectin receptors on murine NK cells.

Multiple NK cell receptors for MHC class I have been identified. They include killer inhibitory receptors and CD94/NKG2 heterodimers in humans and the Ly49 family in mice. Here we report the cloning of murine NKG2A, B and C. The deduced amino acid sequence of mouse NKG2A contains only one consensus cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM). NKG2A from B6 and BALB/c mice differ by six amino acid residues in the extracellular domain. Murine NKG2B, like its human conterpart, appears to be a splice variant of NKG2A and lacks a large portion of the stalk region. Murine NKG2C lacks an ITIM in its cytoplasmic domain, a feature shared by human and rat NKG2C. However, unlike the human counterpart, the transmembrane domain of mouse NKG2C does not contain a charged amino acid residue. Mouse NKG2A mRNA was detected in IL-2-activated NK cells and spleen cells but not in other tissues. The NKG2A gene was localized on the distal portion of chromosome 6 where the NK complex has been located. These results further extend the repertoire of C-type lectin receptors on murine NK cells.

Elongated telomeres in scid mice.

Severe combined immunodeficiency (scid) mice are deficient in the enzyme DNA-PK (DNA-dependent protein kinase) as a result of the mutation in the gene encoding the catalytic subunit (DNA-PKcs) of this enzyme. DNA-PKcs is a member of the phosphatidylinositol 3-kinase superfamily, which includes the human protein ATM (ataxia telangiectasia mutated) and the yeast protein Tel1. Using Q-FISH (quantitative fluorescence in situ hybridization), we show here that scid mice from four different genetic backgrounds have, on average, 1.5-2 times longer telomeres than those of corresponding wild-type mice. Our results point to the possibility that DNA-PKcs may, directly or indirectly, be involved in telomere length regulation in mammalian cells.

Telomere length regulation in mice is linked to a novel chromosome locus.

Little is known about the mechanisms that regulate species-specific telomere length, particularly in mammalian species. The genetic regulation of telomere length was therefore investigated by using two inter-fertile species of mice, which differ in their telomere length. Mus musculus (telomere length >25 kb) and Mus spretus (telomere length 5-15 kb) were used to generate F1 crosses and reciprocal backcrosses, which were then analyzed for regulation of telomere length. This analysis indicated that a dominant and trans-acting mechanism exists capable of extensive elongation of telomeres in somatic cells after fusion of parental germline cells with discrepant telomere lengths. A genome wide screen of interspecific crosses, using M. spretus as the recurrent parent, identified a 5-centimorgan region on distal chromosome 2 that predominantly controls the observed species-specific telomere length regulation. This locus is distinct from candidate genes encoding known telomere-binding proteins or telomerase components. These results demonstrate that an unidentified gene(s) mapped to distal chromosome 2 regulates telomere length in the mouse.

Morphology and function of human benign tumors and normal thyroid tissues maintained in severe combined immunodeficient mice.

In the improved SCID (severe combined immunodeficient) mice, various human benign tumors of the head and neck region were well maintained morphologically and functionally for 3 years until the experiments were terminated, e.g. transplanted parathyroid adenoma secreted parathyroid hormone (PTH) in the SCID mice for more than 1 year. Normal human thyroid tissue was also well maintained in the SCID mice for 3 years. Rapid and high uptake of radioiodine into the transplanted human thyroid tissue was observed. Furthermore, transplanted human thyroid tissue secreted thyroid hormone (T3) and T3 secretion was stimulated by the injection of human thyroid stimulating hormone (TSH). These findings suggest that the improved SCID mice will provide an invaluable experimental system for investigating the function of normal human tissues and the influence of endogenous and exogenous factors on human tissues.

Induction of cancer, actinic keratosis, and specific p53 mutations by UVB light in human skin maintained in severe combined immunodeficient mice.

To study the mechanism and risk of human skin cancer from solar light, we exposed human skin transplanted to severe combined immunodeficient mice to daily doses of UVB for periods of approximately 2 years. We have succeeded for the first time in inducing cancer and solar (actinic) keratosis in human skin by UVB. Of 18 normal skins exposed to doses of 7.3 x 10(5) to 1.8 x 10(6) J/m2, 14 actinic keratoses (77.8%) and 3 squamous cell carcinomas (16.7%) developed, whereas neither actinic keratosis nor cancer was observed in 15 human skins not exposed to UVB. Each human skin showed a different susceptibility, and skins sensitive for actinic keratosis were also sensitive for cancer induction. Among p53 mutations at various sites, mutation at codon 242 (C TGC --> C CGC; Cys --> Arg) was specifically observed in both skin cancers and actinic keratoses. Furthermore, double or triple mutations were induced in all UVB-induced skin cancers and in three of eight actinic keratoses. Most of the mutations (17 of 20) occurred at dipyrimidine sites.

Consecutive maintenance of human solitary and hereditary colorectal polyps in SCID mice.

Recently, the sequential changes from adenoma to adenocarcinoma have been well studied in human colorectal carcinogenesis. To study the precise clonal changes from colorectal polyps to cancer, we have established an experimental system to maintain human colorectal polyps in severe combined immunodeficient (SCID) mice that have been improved by the selective inbreeding of C.B17-scid/scid homozygous male and female showing undetectable serum IgG and IgM (< 1 microgram/ml). Two of two solitary polyps from two nonhereditary colon polyp patients, four of five colon polyps from two Peutz-Jeghers' syndrome patients and one polypoid lesion from a familial polyposis coli (FAP) patient grew very slowly but steadily, at approximately one-tenth the rate of their malignant form, (i.e., adenocarcinoma), in the improved SCID mice and were maintained for a long period (more than 2 years), over several mouse generations. However, two polyps from FAP and Peutz-Jeghers' syndrome patients could not be transplanted further because of microinfection at the transplanted site due to incomplete sterilization of original human tumors prior to surgical operation (endoscopic polypectomy). Transplanted colon polyps had a semitransparent, soft and sticky appearance, with cells containing large amounts of mucin. Malignant transformation of human colon polyp to adenocarcinoma has not been observed during the maintenance period (about 2 years) in SCID mice. In the consecutively maintained human colon polyps, however, K-ras mutations were detected at codon 12, while these mutations were not found in their original polyps in the patients.

Mimosine is a potent clastogen in primary and transformed hamster fibroblasts but not in primary or transformed human lymphocytes.

The cytogenetic effects of mimosine, a naturally occurring plant amino acid known to arrest cell-cycle progression at the G1-S border in cultured cells, have been studied. It was found that mimosine inhibits the cell-cycle progression in a dose-dependent manner in primary and transformed Chinese hamster fibroblasts as well as primary lymphocytes and transformed lymphoblastoid cells of human origin. In the Chinese hamster fibroblast cells, the first division metaphases analysed were found to be highly damaged or pulverized. The damaged cells which could pass through the next cell division, showed very high frequencies of sister chromatid exchanges (SCEs) compared with untreated second division cells. No such cytogenetic alterations could be detected in the human cells. The absence of clastogenic effect in cells of lymphoid origin appears to be related to the known capacity of these cells to undergo apoptosis, thereby efficiently eliminating cells with high frequencies of chromosomal aberrations. Our study demonstrates the clastogenic potency of mimosine and suggests the need for a careful interpretation of the results while using mimosine for cellular or molecular studies pertaining to cell cycle events.