Model of severe malaria in young mice suggests unique response of CD4 T cells.

Severe malaria occurs most in young children but is poorly understood due to the absence of a developmentally-equivalent rodent model to study the pathogenesis of the disease. Though functional and quantitative deficiencies in innate response and a biased T helper 1 (Th1) response are reported in newborn pups, there is little information available about this intermediate stage of the adaptive immune system in murine neonates. To fill this gap in knowledge, we have developed a mouse model of severe malaria in young mice using 15-day old mice (pups) infected with Plasmodium chabaudi.

On the kinetic mechanism of dimethylarginine dimethylaminohydrolase.

Dimethylarginine dimethylaminohydrolase (DDAH, EC 3.5.3.

Expert training with standardized operative technique helps establish a successful penile prosthetics program for urologic resident education.

Introduction: The challenge of resident education in urologic surgery programs is to overcome disparity imparted by diverse patient populations, limited training times, and inequalities in the availability of expert surgical educators. Specifically, in the area of prosthetic urology, only a small proportion of programs have full-time faculty available to train residents in this discipline.

Aim: To examine whether a new model using yearly training sessions from a recognized expert can establish a successful penile prosthetics program and result in better outcomes, higher case volumes, and willingness to perform more complex surgeries.

On the mechanism of dimethylarginine dimethylaminohydrolase inactivation by 4-halopyridines.

Small molecules capable of selective covalent protein modification are of significant interest for the development of biological probes and therapeutics. We recently reported that 2-methyl-4-bromopyridine is a quiescent affinity label for the nitric oxide controlling enzyme dimethylarginine dimethylaminohydrolase (DDAH) (Johnson, C. M.

Prostaglandin E₂mediates spontaneous rhythmic contraction in rabbit detrusor muscle.

Introduction: The purpose of this investigation was to determine if prostaglandin E₂(PGE₂) is produced by rabbit detrusor free of urothelium and demonstrate that PGE₂ is responsible for the generation of spontaneous rhythmic contraction (SRC).

Methods: A bioassay was performed in which contraction frequency in strips of rabbit detrusor was compared before and after addition of superfusate from incubating sections of rabbit detrusor. Specificity was determined by testing the effects of SC-51089, a PGE₂(EP1) antagonist.

Discovery of halopyridines as quiescent affinity labels: inactivation of dimethylarginine dimethylaminohydrolase.

In an effort to develop novel covalent modifiers of dimethylarginine dimethylaminohydrolase (DDAH) that are useful for biological applications, a set of "fragment"-sized inhibitors that were identified using a high-throughput screen are tested for time-dependent inhibition. One structural class of inactivators, 4-halopyridines, show time- and concentration-dependent inactivation of DDAH, and the inactivation mechanism of one example, 4-bromo-2-methylpyridine (1), is characterized in detail. The neutral form of halopyridines is not very reactive with excess glutathione.

Spatial Segregation of Phosphatidylinositol 4,5-Bisphosphate (PIP(2)) Signaling in Immune Cell Functions.

Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is a prevalent phosphoinositide in the inner leaflet of the plasma membrane. PIP(2) associates with an ever-growing list of proteins, and participates in a variety of cellular processes. PIP(2) signaling to the actin cytoskeleton transduces specific signals necessary for changes in morphology, motility, endocytosis, exocytosis, phagocytosis, and cell activation.

Compartmentalization of phosphatidylinositol 4,5-bisphosphate signaling evidenced using targeted phosphatases.

Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is a prevalent phosphoinositide in cell membranes, with important functions in cell signaling and activation. A large fraction of PIP(2) associates with the detergent-resistant membrane "raft" fraction, but the functional significance of this association remains controversial. To measure the properties of raft and nonraft PIP(2) in cell signaling, we targeted the PIP(2)-specific phosphatase Inp54p to either the raft or nonraft membrane fraction using minimal membrane anchors.

The serine acetyltransferase reaction: acetyl transfer from an acylpantothenyl donor to an alcohol.

Serine acetyltransferase is a member of the left-handed parallel beta-helix family of enzymes that catalyzes the committed step in the de novo synthesis of l-cysteine in bacteria and plants. The enzyme has an ordered kinetic mechanism with acetyl CoA bound prior to l-serine and O-acetyl-l-serine released prior to CoA. The rate-limiting step along the reaction pathway is the nucleophilic attack of the serine hydroxyl on the thioester of acetyl CoA.

Chemical mechanism of the serine acetyltransferase from Haemophilus influenzae.

The pH dependence of kinetic parameters was determined in both reaction directions to obtain information about the acid-base chemical mechanism of serine acetyltransferase from Haemophilus influenzae (HiSAT). The maximum rates in both reaction directions, as well as the V/K(serine) and V/K(OAS), decrease at low pH, exhibiting a pK of approximately 7 for a single enzyme residue that must be unprotonated for optimum activity. The pH-independent values of V(1)/E(t), V(1)/K(serine)E(t), V/K(AcCoA)E(t), V(2)/E(t), V(2)/K(OAS)E(t), and V/K(CoA)E(t) are 3300 +/- 180 s(-1), (9.

Kinetic mechanism of the serine acetyltransferase from Haemophilus influenzae.

The kinetic mechanism of serine acetyltransferase from Haemophilus influenzae was studied in both reaction directions. The enzyme catalyzes the conversion of acetyl CoA and L-serine to O-acetyl-L-serine (OAS) and coenzyme A (CoASH). In the direction of L-serine acetylation, an equilibrium ordered mechanism is assigned at pH 6.