The surface of high fluence ion-sputtered Si(111) was found to exhibit a rich variety of transient one- and two-dimensional topographies that may be exploited as tunable self-organized arrays of nanostructures. Such transient effects are only partially described by analytical models of sputter patterning. However, a discrete atom kinetic Monte Carlo simulation model incorporating curvature-dependent sputtering and surface diffusion reproduces many aspects of the transient morphological evolution, and clarifies the minimal model of sputter patterning.

Aim: To determine the diagnostic efficiency of assays routinely used in the investigation of hereditary angiooedema. Methods: Over a four year period, 1144 samples were received for analysis from 907 patients suspected of C1 inhibitor deficiency. Analyses were performed for C4 and C1 inhibitor (functional and immunochemical). Notes were reviewed retrospectively on patients with low serological indicators to determine diagnosis. Results: These are the first data to indicate the sensitivity, specificity, and predictive values of the assays most frequently used to screen for C1 inhibitor deficiency. A combination of low C4 and low C1 inhibitor function has 98% specificity for C1 inhibitor deficiency in this population and a 96% negative predictive value, and is thus a very effective screen. All patients with untreated C1 inhibitor deficiency had a low C4 value. Conclusions: All patients considered for a diagnosis of C1 inhibitor deficiency should have serum examined to measure both C4 and functional C1 inhibitor. If either is normal at presentation this essentially excludes a diagnosis of C1 inhibitor deficiency. These tests can be performed sequentially. If C4 is normal it is not necessary to proceed to C1 inhibitor analysis. If C1 inhibitor function and C4 are both low then a repeat sample should be obtained to confirm the findings. C 1 inhibitor is a serine protease inhibitor that is involved in the regulation of several enzymes including C1r, C1s, plasmin, kallikrein, factor XIa, factor XIIa, and factor XIIf. 1 Deficiency results in recurrent oedema affecting primarily the extremities, face, larynx, and gastrointestinal mucosa. Insufficient normal C1 inhibitor leads to uncontrolled activation of the classical complement pathway, with subsequent reduction of serum C4 and C2 concentrations. 1 C1 inhibitor deficiency may be either hereditary (hereditary angio-oedema; HAE) or acquired. 1 2 HAE has two major variants. In type 1, the classic form, found in 85% of patients, concentrations of C1 inhibitor are low at presentation. The remaining 15% have type 2 HAE, where a dysfunctional C1 inhibitor is produced in normal or increased amounts. 3 The disorder is rare, with HAE affecting around 1 in 10 000-50 000 of the population, 4 and the acquired form affecting a 10th of that number. The diagnosis is important because there is a high associated morbidity and mortality. There are potent and effective treatments available, particularly the androgenic drugs. These may result in serum concentrations of C1 inhibitor and C4 reaching normal values, 5 but the side effects are potentially serious and include hepatocellular adenoma. 6 To our knowledge, there are no data in the literature to indicate the sensitivity, specificity, and predictive values of the assays most frequently used to screen for C1 inhibitor deficiency (C1inhD); namely, serum C4, C1 inhibitor protein, and C1 inhibitor function. We reviewed the data from two laboratories over four years on samples referred from three centres for C1 inhibitor values and reviewe...

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Production of various forms of nonintegrated viral DNA was measured in cultured mouse cells carrying different Fv-1 alleles early after infection with N-tropic or B-tropic retroviruses. Quantitative analyses were performed by agarose gel electrophoresis, transfer to diazobenzyloxymethyl-paper, and molecular hybridization. In permissive infection of Fv-n cells (NIH Swiss and DBA mouse strains) with N-tropic virus and of Fv-1 b cells (BALB/c and C57BL/6 strains) with B-tropic virus, form III (double-stranded linear) DNA first appeared at 3-4 hr and reached a maximum at 8-10 hr; two form I (closed circle) DNAs appeared at 7-8 hr and reached a maximum at or beyond 12 hr. In the two Fv-1 b cells infected with N4ropic virus and in DBA (Fv-1 n) cells infected with B-tropic virus, formation of the two form I DNAs was quantitatively restricted but formation of form III DNA was unaltered. In Fv-1" NIH Swiss mouse embryo cells infected with B-tropic virus, the level of form III DNA was markedly depressed and hence the two form I DNAs were not detectable. In C57BL/6 cells as well as in DBA/2 cells 12 hr after infection, the quantity of form III DNA varied directly with the amount of restricted virus, whereas the quantity of form I DNA varied according to the square of the amount of restricted virus. The significance of these results for understanding the molecular basis of retrovirus replication and its restriction by the Fv-1 gene is discussed. The importance of the mouse Fv-1 gene locus in controlling infection by N-and B-tropic retroviruses has been well recognized in both animal studies and cell culture studies (1-5). This locus, mapped on chromosome 4 of the mouse (6), is presumably responsible for the production of specific inhibitor molecules in the cytoplasm of the cell (7-9). Inactivation of the restricted virus particles appears to be mediated by a virus protein, possibly the p30 core protein (10), which serves as a "target" for the Fv-1 gene product (11,12). However, the precise molecular mechanism of Fv-1 gene restriction is still unknown. Results of various previous investigations (13)(14)(15)(16)(17)(18)(19)(20) indicate that Fv-1 restriction occurs intracellularly at an early step of the virus replication cycle. Of particular significance are the observations (i) that, in Fv-1 restricted infection, the quantity of the cellgenome integrated viral DNA is markedly decreased whereas the formation of nonintegrated viral DNA appears to be unaffected (17-18), and (ii) that transfection by infectious integrated viral DNA is not restricted by the Fv-1 locus of the cell (19,20). These data imply that Fv-1 restriction may occur at or prior to the step of viral DNA integration.In the present study, we quantitatively measured the production of double-stranded linear and circular forms of viral DNA in Fv-1 permissive and restrictive cells early after infection with N-and B-tropic murine retroviruses. The results demonstrate that mouse cells may be assigned to either of two classes with regard to their ability to re...

The ripple phases of a range of mixed-acid phosphatidylcholine derivatives with one saturated C 18 chain and the other chain of variable length or unsaturation were studied using differential scanning calorimetry, x-ray diffraction, and freeze-fracture electron microscopy. The temperature dependences of their ripple wavelength ͑͒, stacking repeat distance (d s ), and the monoclinic angle m defining their unit cell were measured and found to be consistent with an inherently asymmetric ripple phase with an amplitude that slowly increases with temperature. The temperature spans of the ripple phases of the saturated mixed-chain derivatives and the derivatives containing unsaturated chains were found to be larger and smaller, respectively, than those of homoacyl derivatives of the same equivalent chain length. This was shown to be consistent with the slidingchain model proposed by Cevc ͑Biochemistry 30, 7186-7197, 1991͒. The tendency of phosphatidylcholine derivatives to form asymmetric ripple phases and the possible molecular organization of such phases are discussed in terms of different models. X-ray diffraction evidence was found for the existence of a secondary ripple phase with a wavelength about 1.8 times greater than the conventional pretransition ripple phase. This phase is formed in samples freshly cooled from the liquid-crystal phase and tends to persist longer than the conventional ripple phase on cooling to the gel phase. Freeze-fracture electron microscopy suggests that it is symmetric in cross section possibly reflecting the interaction of two opposing pretransition ripples.