A. Brown

Publications (7)6.96 Total impact

• Article: MATURATION OF PENAEID SRHIMP: LIPIDS IN THE MARINE FOOD WEB

  B. S. Middleditch, S. R. Missler, Harry B. Hines, E. S. Chang, J. P. McVey, A. Brown, A. L. Lawrence
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  ABSTRACT: We have determined that certain lipids are required in the diets of penaeid shrimp to promote ovarian maturation. In an attempt to identify appropriate feedstock supplements which contain these lipids, we have examined several invertebrate species from two locations: West Bay, Galveston, and the Gulf of Mexico 50 km offshore from Galveston. At each location, with a few notable exceptions, the lipid profiles for the various species are very similar. This finding implies that many lipids pass through the food web unaltered and that the suitability of a particular invertebrate for inducing ovarian maturation may depend upon the diet of that invertebrate.
  Journal of the World Aquaculture Society 02/2009; 11(1‐4):463 - 470. · 0.71 Impact Factor
• Article: Site-specific interactions of copper(II) ions with heparin revealed with complementary (SRCD, NMR, FTIR and EPR) spectroscopic techniques.

  T R Rudd, M A Skidmore, S E Guimond, M Guerrini, C Cosentino, R Edge, A Brown, D T Clarke, G Torri, J E Turnbull, R J Nichols, D G Fernig, E A Yates
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  ABSTRACT: The interactions between Cu(II) ions and heparin were investigated using several complementary spectroscopic techniques. NMR indicated an initial binding phase involving specific coordination to four points in the structure that recur in slightly different environments throughout the heparin chain; the carboxylic acid group and the ring oxygen of iduronate-2-O-sulfate, the glycosidic oxygen between this residue and the adjacent (towards the reducing end) glucosamine and the 6-O-sulfate group. In contrast, the later binding phase showed little structural specificity. One- and two-dimensional correlated FTIR revealed that complex out of phase (asynchronous) conformational changes also occurred during the titration of Cu(II) ions into heparin, involving the CO and N-H stretches. EPR demonstrated that the environments of the Cu(II) ions in the initial binding phase were tetragonal (with slightly varied geometry), while the later non-specific phases exhibited conventional coordination. Visible spectroscopy confirmed a shift of the absorbance maximum. Titration of Cu(II) ions into a solution of heparin indicated (both by analysis of FTIR and EPR spectra) that the initial binding phase was complete by 15-20 Cu(II) ions per chain; thereafter the ions bound in the non-specific mode. Hetero-correlation spectroscopy (FTIR-CD) improved resolution and assisted assignment of the broad CD features from the FTIR spectra and indicated both in-phase and more complex out of phase (synchronous and asynchronous, respectively) changes in interactions within the heparin molecule during the titration of Cu(II) ions.
  Carbohydrate Research 09/2008; 343(12):2184-93. · 2.33 Impact Factor
• Article: Basal Cell Carcinoma With Matrical Differentiation in a Transplant Patient: A Case Report and Review of the Literature

  F. Ali, A. Brown, L. Gottwald, J. Thomas
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  ABSTRACT: Background: Shadow cells are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. Shadow cells within an otherwise classic basal cell carcinoma (BCC) has been referred to as “BCC with matrical differentiation”. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, none have been reported arising on the background of immunosuppression. Methods: A 58-year-old male cardiac transplant patient had a left hand nodule, which was excised and submitted for routine histologic review. Results: The lesion revealed multiple basaloid tumor masses. In some areas, there was peripheral palisading with stromal retraction artifact, typical of basal cell carcinoma, extending into the deep reticular dermis. The tumor also contained a population of shadow cells, similar to those in pilomatricoma, with basaloid cells in the periphery. Trichohyaline granules were identified in many of the tumor cells. These granules are a hallmark of follicular matrix differentiation. Mitoses were rare. There was no evidence of an infiltrating growth pattern. Conclusion: Basal cell carcinoma with matrical differentiation is a rare subtype of basal cell carcinoma featuring shadow cells, such as those typically seen in pilomatricoma. This tumor has not yet been reported in an immunosuppressed transplant patient.
  Journal of Cutaneous Pathology 06/2008; 32(1):73 - 73. · 1.56 Impact Factor
• Article: Static SIMS for applied surface analysis

  A. Brown, J. C. Vickerman
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  ABSTRACT: A review is presented of the use of static secondary ion mass spectrometry (SSIMS) and fast atom bombardment mass spectrometry (FABMS) in applied surface analysis. Some common criticisms of SIMS are discussed first, and then the experimental apparatus required is described briefly. Four main areas of application have been chosen: catalysts, polymers, glasses and metals, to illustrate the power of SSIMS/FABMS in characterising the chemical state of material surfaces. Finally the very new technique of SSIMS imaging has been described and some preliminary results presented, to indicate its potential in obtaining chemical state information at high spatial resolution.
  Surface and Interface Analysis 09/2004; 6(1):1 - 14. · 1.18 Impact Factor
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  Available from: John C Vickerman

  Article: The relationship between electron and ion induced secondary electron imaging: A review with new experimental observations

  S. Y. Lai, A. Brown, J. C. Vickerman, D. Briggs
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  ABSTRACT: The phenomenalogical and theoretical aspects of secondary electron emission due to ion bombardment in the keV energy range has been reviewed and a comparision of this process with secondary electron emission due to electron bombardment has been made. The similarities and differences between the contrasts in the secondary electron images of test specimens studied with both scanning microfocused Ga+ beams and electron beams have been explained by the mechanisms of the secondary electron emission processes. From ion induced secondary electron images information on the topography, material and crystallographic nature of specimens can be obtained with high surface sensitivity. Differences in surface potential on different areas of a specimen has also been shown to result in voltage contrast effects.
  Surface and Interface Analysis 09/2004; 8(3):93 - 111. · 1.18 Impact Factor
• Article: Sims studies of adsorbate structure: I. CO adsorption on Ru(001), Ni(111) and Ni(100)

  A. Brown, J.C. Vickerman
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  ABSTRACT: The relationship between secondary ion intensities and adsorbate structure is explored by a comparison of experimental SIMS data for CO adsorption on Ni and Ru single crystals with corresponding literature data from techniques sensitive to the chemical structure of adsorbate complexes, i.e. LEED, IR and EELS. For all the surfaces studied, a correlation is established between the proportions of the secondary ions MCO+ and M2CO+ as a function of coverage and the fractional coverages of “bridge-bonded” and “linearly-bonded” CO as measured by the above techniques. These studies demonstrate that there is a clear and accessible relationship between secondary ion emission and surface adsorbate structure. The parameters which influence this relationship will be discussed.
  Surface Science.
• Article: Static sims studies of adsorbate structure: II. CO adsorption on Pd(111); adsorbate-adsorbate interactions on Ru(001), Ni(111) and Pd(111)

  A. Brown, J.C. Vickerman
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  ABSTRACT: In a study of CO adsorption on Pd(111) it is shown that the secondary ion mass spectrum contains information on both adsorbate site geometry and adsorbate coverage. The fractional yields of PdCO+, Pd2CO+ and Pd3CO+, as a function of CO coverage are correlated with the changing site geometries suggested by reflection IR data. A relationship between secondary ion emission and the adsorbate-adsorbate interactions revealed by IR and EELS is also demonstrated for CO adsorption on Ru(001), Ni(111) and Pd(111).
  Surface Science.