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Biomedical subjects

R Lai

Publications and source records attributed to R Lai.

97 records · Page 6Linked to original sources
PubMed1982

The ELISA system for measuring antibody reactive to Fusobacterium nucleatum in the sera of patients with chronic periodontitis.

Humoral IgG, IgA and IgM responses to three typed oral strains of F. nucleatum were examined in patients with chronic periodontitis and in individuals with clinically healthy gingiva. Attempts were made to isolate F. nucleatum from either the pathologic gingival crevices or healthy sulci in this study. Higher levels of IgG and IgA reactive to all three strains were observed in the chronic periodontitis patients; however, there were no differences between the IgM levels in the diseased and healthy individuals. Immunodiffusion studies with rabbit antiserum and adsorption studies of the human sera demonstrated a sharing of antigenic determinants by the F. nucleatum strains. F. nucleatum strains were isolated from 14 of the 15 individuals in the study.

Antibodies, Bacterial↗
PubMedDate not supplied

Modulation of insulin action by vanadate: evidence of a role for phosphotyrosine phosphatase activity to alter cellular signaling.

UNLABELLED: A number of vanadium compounds (vanadate, vanadyl sulfate, metavanadate) have insulin-mimicking actions both in vitro and in vivo. They have multiple biological effects in cultured cells and interact directly with various enzymes. The inhibitory action on phosphoprotein tyrosine phosphatases (PTPs) and enhancement of cellular tyrosine phosphorylation appear to be the most relevant to explain the ability to mimic insulin. We demonstrated that in rat adipocytes both acute insulin effects, e.g. stimulation of IGF-II and transferrin binding and a chronic effect, insulin receptor downregulation, were stimulated by vanadate. Vanadate also enhanced insulin binding, particularly at very low insulin concentrations, associated with increased receptor affinity. This resulted in increased adipocyte insulin sensitivity. Finally vanadate augmented the extent of activation of the insulin receptor kinase by submaximal insulin concentrations. This was associated with a prolongation of the insulin biological response, lipogenesis, after removal of hormone. IN CONCLUSION: in rat adipocytes vanadate promotes insulin action by three mechanisms, 1) a direct insulin-mimetic action, 2) an enhancement of insulin sensitivity and 3) a prolongation of insulin biological response. These data suggest that PTP inhibitors have potential as useful therapeutic agents in insulin-resistant and relatively insulin-deficient forms of diabetes mellitus.

Adipocytes↗
PubMedDate not supplied

From the lab to the clinic: activation of an alpha-2 agonist pathway is neuroprotective in models of retinal and optic nerve injury.

PURPOSE: The selective alpha-2 agonist brimonidine was used as a pharmacological probe to activate alpha 2 receptor-mediated neuroprotective signaling pathways and quantitate the enhancement of retinal ganglion cell survival and function in animals with ischemic retinal and optic nerve injury. METHODS: Two animal models were used to achieve different methods of neuronal insult. The first model involved mechanical injury of the rat optic nerve after treatment with a single intraperitoneal (i.p.) dose of brimonidine or a control vehicle. The second model involving acute retinal ischemic/reperfusion injury was used in a variety of experiments in which rats were treated with either intraperitoneal brimonidine or single dose topical brimonidine at various strengths. In all cases retinal ischemia was induced and maintained followed by reperfusion. In some cases, TUNEL staining was performed on histologic sections of the retinas of rats that had been sacrificed after 24 hours. To examine the activation of neuronal survival pathways at the molecular level, rats were injected with i.p. brimonidine followed by the isolation of mRNAs from whole retinas 24 hours after ischemic injury. RESULTS: Intraperitoneal brimonidine enhanced rat RGC survival and function in the partial crush injury model, and neuroprotection was dose-dependent. Topical application of brimonidine 1 hour before injury was effective in decreasing ischemic retinal injury. Ischemic retinas treated with brimonidine resulted with a large decrease in TUNEL staining. CONCLUSIONS: Treatment with the alpha 2 adrenoreceptor agonist brimonidine was found to confer neuroprotection to retinal ganglion cells in two distinct models of neuronal injury resulting from acute retinal ischemia/reperfusion and calibrated optic nerve compression.

Adrenergic alpha-Agonists↗