PubMed Health⌕ Search

Biomedical subjects

S J Freeman

Publications and source records attributed to S J Freeman.

At least 19 recordsLinked to original sources
PubMed2006

Isospin symmetry of odd-odd mirror nuclei: identification of excited states in N=Z-2 48Mn.

Excited states have been observed in the N=Z-2 odd-odd nucleus 48Mn for the first time. Through comparison with the structure of 48V, a first high-spin study of an odd-odd mirror pair has been achieved. Differences between the T=1 analogue states in this pair have been interpreted in terms of Coulomb effects, with the aid of shell-model calculations in the full pf valence space. Unlike other mirror pairs, the energy differences have been interpreted almost entirely as due to a monopole effect associated with smooth changes in radius (or deformation) as a function of angular momentum. In addition, the large energy shift between analogue negative-parity states is interpreted in terms of the electromagnetic spin-orbit interaction in nuclei.

Journal Article↗
PubMed2005

Evidence for nontermination of rotational bands in 74Kr.

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max).

Journal Article↗
PubMed2004

Is the nuclear spin-orbit interaction changing with neutron excess?

The difference in the energies of the lowest states corresponding to the two nodeless single-particle orbitals outside the Z=50 closed proton shell, h(11/2) and g(7/2), increases with neutron excess. We have measured the Sn(alpha,t) reaction for all seven stable even Sn isotopes and found that the spectroscopic factors are constant for these two states, confirming their characterization as single-particle states. The trend in energies is consistent with a decrease in the nuclear spin-orbit interaction. A similar trend, also suggesting a decreasing spin-orbit splitting, is seen in the energies of the neutron single-particle states outside the N=82 core, i(13/2) and h(9/2).

Journal Article↗
PubMed2001

Alignment delays in the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr.

The ground state rotational bands of the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. (72)Kr shows the most marked effect. It has been widely suggested that these "delayed alignments" arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.

Journal Article↗
PubMed1999

Equilibrium folding properties of the yeast prion protein determinant Ure2.

The yeast non-Mendelian factor [URE3] propagates by a prion-like mechanism, involving aggregation of the chromosomally encoded protein Ure2. The [URE3] phenotype is equivalent to loss of function of Ure2, a protein involved in regulation of nitrogen metabolism. The prion-like behaviour of Ure2 in vivo is dependent on the first 65 amino acid residues of its N-terminal region which contains a highly repetitive sequence rich in asparagine. This region has been termed the prion-determining domain (PrD). Removal of as little as residues 2-20 of the protein is sufficient to prevent occurrence of the [URE3] phenotype. Removal of the PrD does not affect the regulatory activity of Ure2. The C-terminal portion of the protein has homology to glutathione S -transferases, which are dimeric proteins. We have produced the Ure2 protein to high yield in Escherichia coli from a synthetic gene. The recombinant purified protein is shown to be a dimer. The stability, folding and oligomeric state of Ure2 and a series of N-terminally truncated or deleted variants were studied and compared. The stability of Ure2, DeltaGD-N, H2O, determined by chemical denaturation and monitored by fluorescence, is 12.1(+/-0.4) kcal mol-1at 25 degrees C and pH 8.4. A range of structural probes show a single, coincident unfolding transition, which is invariant over a 550-fold change in protein concentration. The stability is the same within error for Ure2 variants lacking all or part of the prion-determining domain. The data indicate that in the folded protein the PrD is in an unstructured conformation and does not form specific intra- or intermolecular interactions at micromolar protein concentrations. This suggests that the C-terminal domain may stabilise the PrD against prion formation by steric means, and implies that the PrD does not induce prion formation by altering the thermodynamic stability of the folded protein.

Amino Acid Sequence↗
PubMed1998

Marrow versus infection in the Charcot joint: indium-111 leukocyte and technetium-99m sulfur colloid scintigraphy.

UNLABELLED: This study evaluated the role of combined leukocyte/marrow scintigraphy in the assessment of the neuropathic or Charcot joint. METHODS: Seventeen patients with (111)In-labeled leukocyte accumulation in 20 radiographically confirmed Charcot joints underwent 99mTc-sulfur colloid marrow scintigraphy. Studies demonstrating labeled leukocyte accumulation without corresponding activity on marrow images were classified as positive for osteomyelitis. Six of the patients also underwent three-phase bone scintigraphy. Bone scans were interpreted as positive for osteomyelitis when focal hyperperfusion, focal hyperemia and focal bony uptake on delayed images were present. Bone images were also interpreted together with labeled leukocyte images using two different criteria for a positive study. One criterion was the presence of labeled leukocyte activity in a region demonstrating abnormal activity on the bone scan, which was more intense than adjacent marrow activity or marrow activity in the corresponding region of the contralateral foot. The second criterion was either a spatially incongruent distribution of the two tracers or hyperintense activity on the leukocyte study, as compared to the bone scan. RESULTS: Leukocyte/marrow studies were positive for osteomyelitis in 4 of the 20 neuropathic joints. Osteomyelitis was present in three of the four joints, whereas in the fourth, infection was confined to overlying soft tissues. None of the 16 neuropathic joints with negative leukocyte/marrow scans were infected. In one patient who underwent below-the-knee amputation, histological analysis confirmed the presence of hematopoietically active marrow corresponding to areas of congruent activity on the leukocyte and marrow images. Three-phase bone scintigraphy was positive in all six neuropathic joints studied; osteomyelitis was present in two of them. Using the first criterion, leukocyte/bone imaging was also positive in all six. Using the second criterion, leukocyte/bone imaging was positive in the two infected neuropathic joints, as well as in three uninfected ones. Leukocyte/marrow scintigraphy was positive in both infected joints and negative in the four without infection. CONCLUSION: Labeled leukocyte accumulation in the uninfected Charcot joint does occur and is related, at least in part, to hematopoietically active marrow. Leukocyte/marrow scintigraphy is a reliable way to differentiate between marrow and infection as the cause of labeled leukocyte accumulation in the neuropathic joint and, in this series, was superior to both three-phase bone scintigraphy and combined leukocyte/bone scintigraphy.

Adult↗
PubMed1995

Demonstration of supernumerary tracheal bronchus by computed tomographic scanning and magnetic resonance imaging.

A bronchus arising directly from the trachea is an infrequent congenital anomaly which usually represents the displaced origin of a normal bronchus. Rarely, a true supernumerary tracheal bronchus occurs supplying an associated tracheal lobe. The case is described of a patient in whom a supernumerary tracheal bronchus and tracheal lobe was demonstrated by computed tomographic scanning and magnetic resonance imaging.

Bronchi↗
PubMed1995

Radioisotopes and their use in the diagnosis and management of thyroid disease.

The use of radioactive isotopes in thyroid evaluation and therapy gives important information in the endocrine assessment of the aged. Thyroid uptake imaging can be used to establish a hypothyroid or hyperthyroid state and can determine the functional status of a palpable nodule. Investigational agents, such as T1 201m DMSA, MIBG, FDG, and Gallium are reviewed in relation to the evaluation of neoplasia. A detailed discussion of thyroid carcinoma ablation and subsequent radioiodine therapy is described, as are radiation safety procedures as they relate to the elderly.

Gallium Radioisotopes↗
PubMed1994

An overview of Canada's mental health system.

In summary, the Canadian health system is an outstanding success, as far as its consumers are concerned. Increasing costs are generally considered to be grounded in factors that could be, and are being, remedied. Health insurance also works very well for that segment of the mental health system that requires intervention by psychiatrists in office or general hospital practice. Unfortunately, certain decisions that were made during the development of the health insurance system have created obstacles to the provision of adequate services to the chronically mentally ill. However, these systemic ailments, which are now being addressed in most provinces, do not seem to have been fatal.

Canada↗
PubMed1993

Muscular paralysis and ventilatory failure caused by hyperkalaemia.

We report the history of a diabetic man presenting with hyperkalaemia and rapidly progressing muscular paralysis with severe respiratory embarrassment. His symptoms resolved rapidly with reduction of the serum potassium concentration. Similar cases have been reported previously but this is a problem that few will have encountered and is a diagnosis which should not be overlooked before artificial ventilation is commenced.

Aged↗
PubMed1992

Marital support and recovery from depression.

A prospective study of 47 married women who met RDC for major depressive disorder investigated the relationship between the social support provided by the husbands and the post-hospital symptom course of the women. Separate taped semistructured interviews were held with the patient and husband at the time of admission. Six months later, symptom course was rated using the LIFE psychiatric status schedule. Only 51% of the sample recovered in the six months. Few demographic or clinical factors were related to symptom course. Recovery was predicted by the depressed woman's ratings of the current marital relationship and by the husband's rating of the pre-morbid relationship but not by the husband's level of expressed criticism or his ratings of the current relationship.

Adult↗