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Acute mesenteric ischemia refers to the sudden onset of intestinal hypo perfusion, one cause of which can be mesenteric venous occlusion. Mesenteric venous thrombosis can present acutely, or in a subacute or chronic manner. Protein S is a vitamin K-dependent plasma glycoprotein synthesized in the endothelium. The characterized function of Protein S is its role in the anti coagulation pathway. We have presented here a case of 34 years old male who presented with acute abdominal pain of sudden onset and later on diagnosed as mesenteric arterial thrombosis with protein S deficiency. Faced with such a case of arterial thrombosis without any known risk factors, the screening for thrombophilia is to be done to prevent further complication and to put patient on adequate lifelong anticoagulant therapy. [ABSTRACT FROM AUTHOR]

The article presents a case study of myopericarditis in a 40 year old female and its unusual cause. It states that the high resolution computer tomography (HRCT) scan of her chest did not demonstrate any aspergillosis features or focal parenchymal lesions. It says that the impression by the cardiologist was progression to myopericarditis.

The structure of vitronectin, an adhesive protein that circulates in high concentrations in human plasma, was predicted through a combination of computational methods and experimental approaches. Fold recognition and sequence-structure alignment were performed using the threading program PROSPECT for each of three structural domains, i.e., the N-terminal somatomedin B domain (residues 1-53), the central region that folds into a four-bladed beta-propeller domain (residues 131-342), and the C-terminal heparin-binding domain (residues 347-459). The atomic structure of each domain was generated using MODELLER, based on the alignment obtained from threading. Docking experiments between the central and C-terminal domains were conducted using the program GRAMM, with limits on the degrees of freedom from a known inter-domain disulfide bridge. The docked structure has a large inter-domain contact surface and defines a putative heparin-binding groove at the inter-domain interface. We also docked heparin together with the combined structure of the central and C-terminal domains, using GRAMM. The predictions from the threading and docking experiments are consistent with experimental data on purified plasma vitronectin pertaining to protease sensitivity, ligand-binding sites, and buried cysteines.

Following a long-standing suggestion of Riordan et al. [Riordan, J. F., McElvany, K. D., and Borders, C. L., Jr. (1977) Science 195, 884-885], we sought to exploit chemically activated arginines as probes to characterize the microenvironmental effects in enzymes that mediate the recognition of anionic substrates. A micellar simulation study establishes that octylguanidine (OGn) becomes chemically activated upon incorporation into both cetyltrimethylammonium bromide (CTAB) and Triton X-100 micelles and that the activations correlate with the pKa diminutions induced in its guanidinium group by the effects of electrostatic or nonelectrostatic nature as reflected in the results of pH and salt titration experiments. Next, a protein modification study establishes that the modifiable arginines in a number of enzymes also have diminished pKa's, again due to effects of electrostatic or nonelectrostatic nature as reflected in the results of pH and salt titration experiments. Warwicker's finite difference Poisson--Boltzmann algorithm [Warwicker, J. (1992) J. Mol. Biol. 223, 247-257] is applied to several of the enzymes with available crystal structure coordinates, and indeed, their chemically activated arginines are found to be in an electrostatic microenvironment that can diminish their pKa's, with the magnitudes of these diminutions matching closely the diminutions measured experimentally. Finally, the chemically activated arginines are examined with respect to their atomic atmosphere and are thus found to occur in a local microenvironment that would facilitate their roles as anion anchors. Thus, electrostatic and solvation effects are found to be critical determinants of the arginine role as an anion anchor.

Two coumarin derived alpha-dicarbonyls, HOCGO and DMACGO, are presented as pH, polarity and quencher sensitive fluorescent reporters for proteins that can be targeted at reactive arginines. Both inactivate a number of enzymes that feature functionally critical and chemically susceptible arginyls. Both are chemoselective in responding towards Arg side chain but not towards Cys or Lys side chains under suitably dilute conditions. With pKapp approximately 6.7, HOCGO can serve as a pH sensor, while with pKapp << 4.0, DMACGO is better suited as a polarity sensor. A contrasting set of changes are manifest in the CGOs upon protein interaction that are either attributable to Arg modification or to the noncovalent probe associations with hydrophobic protein domains. DMACGO probes a single hydrophobic site on ovalbumin while HOCGO is largely unresponsive to this protein. Three to five arginyls are modified in HSA and BSA by HOCGO as well as DMACGO, while the latter also probes two hydrophobic sites on both these proteins. HOCGO modifies a single arginine in LDH active site, while its adducts with H4 and M4LDH isozymes titrate to the apparent pKa of 7.8. Other proteins labeled with HOCGO or DMACGO reveal a number of variations that can furnish information about the microenvironment in the sites probed. The CGOs are thus potentially useful reporters of protein domains that feature reactive arginines. Suitable experimental condition are defined based on mechanistic considerations that may be used in applying the CGOs as Arg modifiers and as fluorescent probes.

4-Substituted styrylglyoxals have been synthesized and found to benefit from borate catalysis to serve as highly reactive arginine modifiers. A study of the mechanism in arginine modification has affirmed: (i) the role of electronic effects in modulating the arginine reactivity in alpha-dicarbonyls, (ii) the intermediacy in the reaction of a reversible arginine-alpha-dicarbonyl complex and (iii) the identity of the nucleophilic attack at ketone as the rate determining step in the arginine reaction with arylglyoxals. 4-Methoxystyrylglyoxal and 4-(N,N-dimethylamino)phenylglyoxal were used as the probes in analyzing some representative enzymes for the reactivities of their susceptible arginyls. The susceptible arginyls in lactate and malate dehydrogenases were thus found to be appreciably reactive while those in carboxypeptidase-A and pyruvate kinase were only moderately reactive.