In vivo kinetics of 123 iodine-labelled insulin in skeletal muscle of patients with type 2 diabetes. Effect of metformin.

BACKGROUND: The capillary filtration of albumin (CFA) is often increased in diabetic patients. However, the transcapillary transfer of insulin is considered to be a key stage in insulin action. The aim was to study the in vivo kinetics of 123I-labelled human insulin in the skeletal muscle of type 2 diabetic patients with an increase in CFA and to evaluate the effect of metformin, using a noninvasive method. METHODS: Ten type 2 diabetic patients and 6 healthy control subjects were investigated. After an i.v injection of 123I-labelled insulin, venous samples were drawn during 75 minutes and radioactivity was counted externally by a gammacamera on the contralateral forearm before, during and after venous compression. The changes in the serum percentages of bound and free 123I were followed during the entire test and the forearm iodine bound to insulin was estimated by multiplying the forearm counted radioactivity by the serum percentage of bound iodine at the same time. RESULTS: In the diabetic patients the maximal increase in the forearm iodine bound to insulin during venous compression was lower (p=0.06), and 10 minutes after removal of venous compression the forearm retention of labelled insulin was significantly lower (p<0.0005) than in controls. After one month of metformin treatment, retention of labelled insulin significantly increased (p<0.001) but was still significantly lower than in the controls (p<0.001). CONCLUSION: The in vivo kinetics of (123) I-labelled insulin procedure allows the study of skeletal muscle metabolism provided venous compression is exerted. In type 2 diabetic patients a reduction of insulin transfer from capillary to tissue despite an increase in CFA, and a reduction of the time spent by insulin in the tissues contribute to insulin resistance. The latter disorder may be improved by metformin.

Systemic cytokine profiles in BALB/c mice immunized with trivalent influenza vaccine containing MF59 oil emulsion and other advanced adjuvants.

We have studied serum cytokine profiles in BALB/c mice after immunization with influenza vaccine alone or combined with the following adjuvants: alum; MF59 emulsion; MF59 containing the muramyl peptide N-acetyl-muramyl-L-alanyl-D-isoglutaminyl-L-alanine-2-(1,2- dipalmitoyl-sn-glycero-3-(hydroxyphosphoryloxy)) ethylamide (MTP-PE); MF59 plus the lipid A analogue monophosphoryl lipid A; MF59 plus the Quil A saponin fraction LTC; or LTC alone. Pooled mouse sera were analyzed by ELISA at various times after immunization for IL-1 alpha, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IFN-gamma, and TNF-alpha. In naive mice, vaccine alone induced low levels of IL-3 and IL-5 only; vaccine plus alum induced a low IL-6 response as well. The MF59-based adjuvants significantly increased the IL-5 and IL-6 levels, whereas Quil A LTC induced strong IFN-gamma and measurable IL-2 responses, in addition to moderate IL-5 and IL-6. In previously infected mice, MF59 and MF59/MTP-PE were capable of generating IFN-gamma responses, as well as IL-5 and IL-6. All of the cytokine responses were rapid (peaking 3 to 12 h postimmunization) and short lived. In naive mice, the MF59 adjuvants induced serum cytokine profiles that are consistent with a primarily Th2-type response, whereas the Quil A LTC induced cytokines associated with both Th1 and Th2 responses. Ab analyses indicated that, although the adjuvants strongly affected the magnitude of the humoral response, there was no obvious correlation between the cytokine profile observed and the subclasses of Ab induced.

Cationic lipids direct a viral glycoprotein into the class I major histocompatibility complex antigen-presentation pathway.

Recombinant glycoprotein B (gB) of herpes simplex virus (HSV) was processed and presented by class I major histocompatibility complex (MHC) molecules after delivery into cells by using N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl sulfate (DOTAP), a commercially available cationic lipid used for DNA transfection. Cells treated with DOTAP-associated gB were susceptible to lysis by class I MHC-restricted, HSV-specific cytotoxic T lymphocytes (CTL), and the treated cells restimulated memory gB-specific CTL activity in spleen cells from HSV-infected mice. gB-specific CTL responses were detected in mice immunized with recombinant gB and DOTAP but not in those receiving gB emulsified in complete Freund's adjuvant. Thus, cationic lipids may facilitate induction of CD8+ T-cell responses in vaccinations with recombinant antigens, and they may serve as readily available reagents for dissecting class I MHC immunity to viruses and other intracellular pathogens.