A mössbauer study in the troilite-pyrrhotite system

SUMMARY In this thesis, several compounds in the iron monosulfide system ranging in composition from troilite (FeS) to pyrrhotite (Fe7S8) -have been studied. Emphasis has been placed on the temperature dependence of the characteristics measured by the Mössbauer effect. In troilite, the crystallographic phase transition near 400 0 K was of special interest. In pyrrhotite; the distribution of vacancies and the ordering of ferrous and ferric ions was examined. The investigation has included the development of an improved method for preparation of samples, which minimizes oxygen impurity. In the region of nearly stoichiometric FeS, we have proven conclusively that the Morin transition is only associated with the R3m phase, it is noted that the Néel en Morin transitions must be accompanied by changes in magnetic space group. The probable existence of iron-rich FeS, with interstitial iron, has been made plausible. Interstitials in sulfur-rich FeS have not been observed. The spin directions in both the R3m and P62c phases have been deduced from the combined quadrupole and magnetic hyperfine splittings, possible disagreement with previously assumed directions has been pointed out. Further the orbital ground state of the ferrous ions in their crystalline surroundings has been determined from the temperature dependence and of the quadrupole splitting and the calculated lattice contribution to the electric field gradient tensor...

Reduced Cancer Incidence in Huntington's Disease: Analysis in the Registry Study

Background: People with Huntington's disease (HD) have been observed to have lower rates of cancers. Objective: To investigate the relationship between age of onset of HD, CAG repeat length, and cancer diagnosis. Methods: Data were obtained from the European Huntington's disease network REGISTRY study for 6540 subjects. Population cancer incidence was ascertained from the GLOBOCAN database to obtain standardised incidence ratios of cancers in the REGISTRY subjects. Results: 173/6528 HD REGISTRY subjects had had a cancer diagnosis. The age-standardised incidence rate of all cancers in the REGISTRY HD population was 0.26 (CI 0.22-0.30). Individual cancers showed a lower age-standardised incidence rate compared with the control population with prostate and colorectal cancers showing the lowest rates. There was no effect of CAG length on the likelihood of cancer, but a cancer diagnosis within the last year was associated with a greatly increased rate of HD onset (Hazard Ratio 18.94, p < 0.001). Conclusions: Cancer is less common than expected in the HD population, confirming previous reports. However, this does not appear to be related to CAG length in HTT. A recent diagnosis of cancer increases the risk of HD onset at any age, likely due to increased investigation following a cancer diagnosis

Clinical and genetic characteristics of late-onset Huntington's disease

Background: The frequency of late-onset Huntington's disease (&gt;59 years) is assumed to be low and the clinical course milder. However, previous literature on late-onset disease is scarce and inconclusive. Objective: Our aim is to study clinical characteristics of late-onset compared to common-onset HD patients in a large cohort of HD patients from the Registry database. Methods: Participants with late- and common-onset (30–50 years)were compared for first clinical symptoms, disease progression, CAG repeat size and family history. Participants with a missing CAG repeat size, a repeat size of ≤35 or a UHDRS motor score of ≤5 were excluded. Results: Of 6007 eligible participants, 687 had late-onset (11.4%) and 3216 (53.5%) common-onset HD. Late-onset (n = 577) had significantly more gait and balance problems as first symptom compared to common-onset (n = 2408) (P &lt;.001). Overall motor and cognitive performance (P &lt;.001) were worse, however only disease motor progression was slower (coefficient, −0.58; SE 0.16; P &lt;.001) compared to the common-onset group. Repeat size was significantly lower in the late-onset (n = 40.8; SD 1.6) compared to common-onset (n = 44.4; SD 2.8) (P &lt;.001). Fewer late-onset patients (n = 451) had a positive family history compared to common-onset (n = 2940) (P &lt;.001). Conclusions: Late-onset patients present more frequently with gait and balance problems as first symptom, and disease progression is not milder compared to common-onset HD patients apart from motor progression. The family history is likely to be negative, which might make diagnosing HD more difficult in this population. However, the balance and gait problems might be helpful in diagnosing HD in elderly patients