Individual and Combined Evaluation of Specific Inflammatory Biomarkers along with Neutrophil, Lymphocyte, and Platelet Counts in Predicting Poststroke Disability Severity Among Acute Ischemic Stroke Patients in a Tertiary Hospital in Pampanga, Philippines

Introduction/Objective

Numerous studies considered Neutrophil-to-Lymphocyte ratio (NLR), Platelet-to-Lymphocyte ratio (PLR), and Mean Platelet Volume (MPV) as inflammatory biomarkers in assessing the functional outcomes of Acute Ischemic Stroke (AIS) Patients. Presumably, no other study has evaluated all three markers in varying levels of combinations. The study aims to evaluate the predictive potential of specific CBC parameters (Neutrophils, Lymphocytes, and Platelets), their individual ratios (NLR, PLR, and MPV), and their combinations (NLR-PLR, NLR- MPV, PLR-MPV, and PLR-NLR-MPV).

Methods/Case Report

This retrospective study involved 52 AIS patients from a hospital in Pampanga, Philippines, at least 18 years of age, have no pre-existing conditions and prior treatments/medications. Modified Rankin Scale (mRS) score, medical history, age, and gender were gathered. Specific CBC parameters upon admission were analyzed to derive individual ratios. The combined biomarkers, categorized into Levels 2, 1, and 0, indicate high values for all biomarkers involved, high values for any of the biomarkers (one or two high value/s for PLR-NLR-MPV), and no high values for any of the biomarkers, respectively.

Results (if a Case Study enter NA)

Results showed that elevated NLR (OR=14.5; p=0.021) and MPV (OR=24.1; p=0.047) are risk factors in developing evident poststroke disability (mRS 2-5) and mortality (mRS 6), respectively. Furthermore, level 2 NLR-MPV (OR=77.0; p=0.040) and PLR-MPV (OR=105; p=0.027) are risk factors on mortality. Level 2 PLR-NLR (OR=15.0; p=0.021) and level 1 NLR-MPV (OR=13.5; p=0.024) are risk factors in developing evident poststroke disability. Lastly, levels 1 (OR=13.5; p=0.024) and 2 (OR=77.0; p=0.040) PLR-NLR-MPV are risk factors in developing evident poststroke disability and mortality, respectively.

Conclusion

Patients with neutrophilia, elevated NLR, level 2 PLR-NLR, and level 1 NLR-MPV and PLR-NLR-MPV are more likely to develop evident poststroke disability; while patients with elevated MPV and Level 2 NLR-MPV, PLR- MPV, and PLR-NLR-MPV pose higher mortality risk. Greater sample size is recommended for studies with the same purpose to advance research for better AIS outcomes.

The function of interdomain interactions in controlling nucleotide exchange rates in transducin

The intramolecular contacts in heterotrimeric G proteins that determine the rates of basal and receptor-stimulated nucleotide exchange are not fully understood. The alpha subunit of heterotrimeric G proteins consists of two domains: a Ras-like domain with structural homology to the monomeric G protein Ras and a helical domain comprised of six alpha-helices. The bound nucleotide lies in a deep cleft between the two domains. Exchange of the bound nucleotide may involve opening of this cleft. Thus interactions between the domains may affect the rate of nucleotide exchange in G proteins. We have tested this hypothesis in the alpha subunit of the rod cell G protein transducin (Galpha(t)). Site-directed mutations were prepared in a series of residues located at the interdomain interface. The proteins were expressed in vitro in a reticulocyte lysate system. The rates of basal and rhodopsin-catalyzed nucleotide exchange were determined using a trypsin digestion assay specifically adapted for kinetic measurements. Charge-altering substitutions of two residues at the interdomain interface, Lys(273) and Lys(276), increased basal nucleotide exchange rates modestly (5-10-fold). However, we found no evidence that interactions spanning the two domains in Galpha(t) significantly affected either basal or rhodopsin-catalyzed nucleotide exchange rates. These results suggest that opening of the interdomain cleft is not an energetic barrier to nucleotide exchange in Galpha(t). Experiments with Galpha(i1) suggest by comparison that the organization and function of the interdomain region differ among various G protein subtypes.

Rapid activation of transducin by mutations distant from the nucleotide-binding site: evidence for a mechanistic model of receptor-catalyzed nucleotide exchange by G proteins

G proteins act as molecular switches in which information flow depends on whether the bound nucleotide is GDP ("off") or GTP ("on"). We studied the basal and receptor-catalyzed nucleotide exchange rates of site-directed mutants of the alpha subunit of transducin. We identified three amino acid residues (Thr-325, Val-328, and Phe-332) in which mutation resulted in dramatic increases (up to 165-fold) in basal nucleotide exchange rates in addition to enhanced receptor-catalyzed nucleotide exchange rates. These three residues are located on the inward facing surface of the alpha5 helix, which lies between the carboxyl-terminal tail and a loop contacting the nucleotide-binding pocket. Mutation of amino acid residues on the outward facing surface of the same alpha5 helix caused a decrease in receptor-catalyzed nucleotide exchange. We propose that the alpha5 helix comprises a functional microdomain in G proteins that affects basal nucleotide release rates and mediates receptor-catalyzed nucleotide exchange at a distance from the nucleotide-binding pocket.

The amino terminus of the fourth cytoplasmic loop of rhodopsin modulates rhodopsin-transducin interaction

Rhodopsin is a seven-transmembrane helix receptor that binds and catalytically activates the heterotrimeric G protein transducin (G(t)). This interaction involves the cytoplasmic surface of rhodopsin, which comprises four putative loops and the carboxyl-terminal tail. The fourth loop connects the carboxyl end of transmembrane helix 7 with Cys(322) and Cys(323), which are both modified by membrane-inserted palmitoyl groups. Published data on the roles of the fourth loop in the binding and activation of G(t) are contradictory. Here, we attempt to reconcile these conflicts and define a role for the fourth loop in rhodopsin-G(t) interactions. Fluorescence experiments demonstrated that a synthetic peptide corresponding to the fourth loop of rhodopsin inhibited the activation of G(t) by rhodopsin and interacted directly with the alpha subunit of G(t). A series of rhodopsin mutants was prepared in which portions of the fourth loop were replaced with analogous sequences from the beta(2)-adrenergic receptor or the m1 muscarinic receptor. Chimeric receptors in which residues 310-312 were replaced could not efficiently activate G(t). The defect in G(t) interaction in the fourth loop mutants was not affected by preventing palmitoylation of Cys(322) and Cys(323). We suggest that the amino terminus of the fourth loop interacts directly with G(t), particularly with Galpha(t), and with other regions of the intracellular surface of rhodopsin to support G(t) binding.

Mutation of the fourth cytoplasmic loop of rhodopsin affects binding of transducin and peptides derived from the carboxyl-terminal sequences of transducin alpha and gamma subunits

The role of the putative fourth cytoplasmic loop of rhodopsin in the binding and catalytic activation of the heterotrimeric G protein, transducin (G(t)), is not well defined. We developed a novel assay to measure the ability of G(t), or G(t)-derived peptides, to inhibit the photoregeneration of rhodopsin from its active metarhodopsin II state. We show that a peptide corresponding to residues 340-350 of the alpha subunit of G(t), or a cysteinyl-thioetherfarnesyl peptide corresponding to residues 50-71 of the gamma subunit of G(t), are able to interact with metarhodopsin II and inhibit its photoconversion to rhodopsin. Alteration of the amino acid sequence of either peptide, or removal of the farnesyl group from the gamma-derived peptide, prevents inhibition. Mutation of the amino-terminal region of the fourth cytoplasmic loop of rhodopsin affects interaction with G(t) (Marin, E. P., Krishna, A. G., Zvyaga T. A., Isele, J., Siebert, F., and Sakmar, T. P. (2000) J. Biol. Chem. 275, 1930-1936). Here, we provide evidence that this segment of rhodopsin interacts with the carboxyl-terminal peptide of the alpha subunit of G(t). We propose that the amino-terminal region of the fourth cytoplasmic loop of rhodopsin is part of the binding site for the carboxyl terminus of the alpha subunit of G(t) and plays a role in the regulation of betagamma subunit binding.

Lack of association of G-protein beta 2- and gamma 2-subunit N-terminal fragments provides evidence against the coiled-coil model of subunit-beta gamma assembly

The association between peptides from bovine G-protein beta 2- and gamma 2-subunits was studied by CD spectroscopy and cross-linking. Both peptides had approximately 25% stable alpha-helical structure at 25 degrees C, but there was no increase on mixing subunits as expected for coiled-coil formation. Also, disulphide cross-linking gave more beta 2 beta 2 homodimer than beta 2 gamma 2 heterodimer. These data do not support the proposed N-terminal coiled-coil model of beta gamma-subunit association.