The crystal structure of an Fe-superoxide dismutase from the hyperthermophile Aquifex pyrophilus at 1.9 A resolution: structural basis for thermostability

The incidence of stress fractures is increasing among competitive and recreational athletes as well as among children and the elderly. By understanding the continuum of bone's response to stress and maintaining an appropriate index of suspicion, the health care provider can diagnose these injuries appropriately. An accurate history and examination is essential and will differentiate stress fractures from other stress reactions. The more common stress fractures are discussed.     

An outbreak of malignant catarrhal fever in young rusa deer (Cervus timorensis)

On the basis of clinical signs and histological findings eight 9-month-old male rusa deer (Cervus timorensis) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5 degrees C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested polymerase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer.     

Homogeneity of fruits and vegetables comminuted in a vertical cutter mixer

The homogeneity of comminuted composites of 20 lb samples of apples, cabbage, and green beans containing field-incurred residues of p, p'-methoxychlor was studied to determine whether a 5 min comminution in a 40 qt vertical cutter mixer produces a homogeneous composite and whether the size of test portions used accurately represents the composite. Duplicate test portions of 100, 50, 25, 10, 5, and 2 g taken from each of 6 separate sections of the mixer were analyzed by standard pesticide residue methodology for p, p'-methoxychlor. Results of this study confirmed that comminution of fresh produce in a 40 qt vertical cutter mixer, according to instructions described in the U.S. Food and Drug Administration's Pesticide Analytical Manual, Volume I, Section 203B, produces a homogeneous composite. No significant differences were found in the data for the 3 crops taken from the 6 sections of the mixer. Test portion weights of 100, 50, and 25 g produced equivalent results for all 3 crops. Statistically significant differences were observed for cabbage at 2, 5, and 10 g and for green beans at 2 g.     

Myocardial imaging with technetium-99m-tetrofosmin: comparison of one-day and two-day protocols

There is no evidence of myocardial redistribution after tetrofosmin injection, therefore, two separate injections are needed to differentiate scar from ischemia with this tracer. The injections can be given on the same day (one-day protocol) or on separate days (two-day protocol). As part of a Phase II clinical study, a one-day protocol was compared with a two-day protocol. METHODS: Fifty-five patients with suspected coronary artery disease were studied according to the following protocol: on the first day at rest, anterior, left lateral, left anterior oblique 40 degrees and 70 degrees images were acquired 30 min after injection of 8 mCi of tetrofosmin for 5 min each. Two days later, exercise and rest images were acquired on the same day. At peak exercise, 8 mCi of tetrofosmin were injected and 30 min later the same four standard planar images were recorded as on Day one. Four hours after the exercise injection, 24 mCi of tetrofosmin were injected at rest and imaging was repeated 30 min later. Qualitative comparisons between the one- and two-day protocols were performed in 50 patients in whom all data were available following blinded evaluation of images by three readers. RESULTS: All three readers reported identical results for the 26 patients. A difference in extent or location between the observers was found in seven patients, differences between normal and abnormal in eight patients, while discrepancies between ischemia and necrosis were noted in four patients. In five patients, an ischemic area was found according to the one-day protocol, but according to the data of the two-day protocol, this area was judged to be necrotic. One observer reported the opposite in one patient. These discrepancies between the reversibility of defects were restricted to the inferior wall. Comparison with 201Tl data showed no systematic pattern of variation. CONCLUSION: Tetrofosmin can be used in a one-day protocol. However, in planar imaging, the inferior wall should be reported with caution.     

The rank one mixed μ problem and ‘kharitonov-type’ analysis

The general mixed μ problem has been shown to be NP hard, so that the exact solution of the general problem is computationally intractable, except for small problems. In this paper we consider not the general problem, but a particular special case of this problem, the rank one mixed μ problem. We show that for this case the mixed μ problem is equivalent to its upper bound (which is convex), and it can in fact be computed easily (and exactly). This special case is shown to be equivalent to the so-called ‘affine parameter variation’ problem (for a polynomial with perturbed coefficients) which has been examined in detail in the literature, and for which several celebrated ‘Kharitonov-type’ results have been proven.     

Formation of C4 species in the deactivation of a Pd/SiO2 catalyst during the selective hydrogenation of acetylene

The deactivation characteristics of Pd/SiO₂ in the selective hydrogenation of acetylene were correlated with changes in the amount of the C4 species produced. The amounts of butenes produced changed in parallel with the catalyst activity, indicating that the rate limiting step for butene production was the same as that for acetylene hydrogenation. On the other hand, the amount of 1,3-butadiene produced changed, showing a maximum with catalyst deactivation because 1,3-butadiene is an intermediate in the sequential reaction process which involves both the production and consumption of 1,3-butadiene. This was verified by a simultaneous TG/reaction experiment showing that 1,3-butadiene was a precursor of green oil. The catalyst showed a self-regenerative behavior in its activity and the amounts of C4 species produced during the early stage of deactivation because two opposite factors, which contributed to either the lowering or the promotion of activity, were involved in the process. A specific type of polymer species, produced during the initial period of deactivation, is proposed to be responsible for the promotion of catalyst activity.     

Impairment of energy metabolism and excitotoxic cell death in Huntington disease

The gene for Huntington's disease is widely expressed in brain and yet the illness is characterized pathologically by a distinct regional pattern of cell death. Various theories for this selective vulnerability have been offered but the most compelling remains that of abnormal energy metabolism. These issues are reviewed.