Metabolic correction in the management of diabetic peripheral neuropathy: improving clinical results beyond symptom control.

Current Clinical Management Guidelines of Diabetic Peripheral Neuropathy (DPN) are based on adequate glucose control and symptomatic pain relief. However, meticulous glycemic control could delay the onset or slow the progression of diabetic neuropathy in patients with DM type 2, but it does not completely prevent the progression of the disease. Complications of DPN as it continues its natural course, produce increasing pain and discomfort, loss of sensation, ulcers, infections, amputations and even death. In addition to the increased suffering, disability and loss of productivity, there is a very significant economic impact related to the treatment of DPN and its complications. In USA alone, it has been estimated that there are more than 5,000,000 patients suffering from DPN and the total annual cost of treating the disease and its complications is over $10,000 million dollars. In order to be able to reduce complications of DPN, it is crucial to improve or correct the metabolic conditions that lead to the pathology present in this condition. Pathophysiologic mechanisms implicated in diabetic neuropathy include: increased polyol pathway with accumulation of sorbitol and reduced Na+/K+-ATPase activity, microvascular damage and hypoxia due to nitric oxide deficit and increased oxygen free radical activity. Moreover, there is a decrease in glutathione and increase in homocysteine. Clinical trials in the last two decades have demonstrated that the use of specific nutrients can correct some of these metabolic derangements, improving symptom control and providing further benefits such as improved sensorium, blood flow and nerve regeneration. We will discuss the evidence on lipoic acid, acetyl-L-carnitine, benfotiamine and the combination of active B vitamins L-methylfolate, methylcobalamin and piridoxal-6-phosphate. In addition, we discuss the role of metformin, an important drug in the management of diabetes, and the presence of specific polymorphic genes, in the risk of developing DPN and how metabolic correction can reduce these risks.

Degradation of phenol by mechanical activation of a rutile catalyst.

In the present paper a novel mechanochemical process for the elimination of organic pollutants dissolved in water is proposed. In this regard, phenol aqueous solutions (100mgL(-1)) were ball-milled for 0, 12, 18, 24, 36, 48, and 72h with and without a well-characterized (XRD, SEM, and N(2) Adsorption), rutile powder catalyst and the reaction products analyzed with UV and GC/MS. It was found that when the catalyst was not included in the process, phenol was not affected, but when it was included, phenol was decomposed. The catalyst itself did not change and the reaction follows a pseudo-first-order kinetics. Besides, intermediates which are characteristic of the ()OH radical mechanism were found in the reaction products. Then, a mechanism similar to those accepted for other advanced oxidation processes was proposed. The value measured for the pseudo-first-order reaction constant was very low, indicating that the reported process is inefficient. Nevertheless, this problem could be solved by applying catalysts consisting of particles with smaller diameters.

Paranitrophenol liquid-phase adsorption in dealuminated Y zeolite.

Was studied the liquid-phase paranitrophenol (PNP) dynamic adsorption in a packed bed adsorption reactor (PBAR), filled with dealuminated Y zeolite (DAY) and granulated active carbon (GAC). In addition, was measured the equilibrium maximum amount of adsorption for the system: PNP aqueous solution-DAY zeolite, at 300 K, to compare it with other adsorbents. The DAY zeolite and the GAC were characterized with adsorption methods. The DAY zeolite was, as well, characterized with: XRD, SEM and EDAX. Some of the operational parameters which characterize the performance of the PBAR were calculated. To evaluate these results, was considered the breakthrough experiment as a frontal analysis chromatographic event and were applied the DeVault and van Deemter equations. It was concluded that the reactor filled with the DAY zeolite operates more efficiently than those filled with the GAC, because of the stronger adsorbate-adsorbent interaction in the case of the DAY zeolite.

Kinetics of monoclonal anti-epidermal growth factor receptor antibody (IOR EGF/r3)-induced apoptosis in human carcinoma bearing nude mice

Apoptosis seems to play an important role in cancer immunotherapy outcome. We have studied the kinetic pattern of apoptosis induction in H125 human lung carcinoma xenografts after treatment with the monoclonal antibody (MAb) anti-epidermal growth factor receptor (EGFr) IOR EGF/r3. Tumor-bearing nude mice were injected intravenously with a single 8 mg/kg dose of IOR EGF/r3 and tumor specimens were taken up to 30 days post treatment. Apoptosis was measured by morphometric analysis of the histological sections at each tumor specimen over time points. The results showed a significant apoptotic response in tumors within six days after injection of this MAb reaching a peak at 20 days post treatment. The kinetics were very broad, with apoptotic cells present over the entire time-frame. However, the time course of the apoptotic index showed a significant difference to the mitotic index. Finally, the MAb-induced apoptosis was related to tumor growth delay indicating a probable arrest of cell cycle and a corresponding inhibition of tumor progression, which was corroborated by the Ki67 and proliferating cell nuclear antigen (PCNA) biomarkers.

Pharmacokinetics of vitamin C: insights into the oral and intravenous administration of ascorbate

There is a strong advocacy movement for large doses of vitamin C. Some authors argue that the biological half-life for vitamin C at high plasma levels is about 30 minutes, but these reports are the subject of some controversy. NIH researchers established the current RDA based upon tests conducted 12 hours (24 half lives) after consumption. The dynamic flow model refutes the current low-dose recommendations for dietary intakes and links Pauling's mega-dose suggestions with other reported effects of massive doses of ascorbate for the treatment of disease. Although, a couple of controlled clinical studies conducted at The Mayo Clinic did not support a significant benefit for terminal cancer patients after 10 grams of once-a-day oral vitamin C, other clinical trials have demonstrated that ascorbate may indeed be effective against tumors when administered intravenously. Recent studies confirmed that plasma vitamin C concentrations vary substantially with the route of administration. Only by intravenous administration, the necessary ascorbate levels to kill cancer cells are reached in both plasma and urine. Because the efficacy of vitamin C treatment cannot be judged from clinical trials that use only oral dosing, the role of vitamin C in cancer treatment should be reevaluated. One limitation of current studies is that pharmacokinetic data at high intravenous doses of vitamin C are sparse, particularly in cancer patients. This fact needs prompt attention to understand the significance of intravenous vitamin C administration. This review describes the current state-of-the-art in oral and intravenous vitamin C pharmacokinetics. In addition, the governmental recommendations of dose and frequency of vitamin C intake will also be addressed.

Topical disposition of two strengths of a 125I-rhEGF jelly in rat skin wounds.

Growth factors have proved to be an effective therapeutic strategy. However, some controversies have arisen concerning their efficacy in topical wound treatments. Stabilization of epidermal growth factors at the wound site and long-lasting receptor occupancy are important factors for wound repair. This study evaluated the cumulative profiles of two jellies containing 10 or 20 microg of 125I-rhEGF per gram of jelly, in a rat full-thickness skin lesion model. The prolonged time-courses at the wound sites for both strengths compared with saline solutions previously evaluated using a similar skin lesion model are reported. It seems that these two topical formulations that provide more sustained amounts of 125I-rhEGF over the period of sampling, would probably achieve the required wound healing response in terms of cell proliferation, collagen deposition and protein synthesis. Further studies need to be developed in order to elucidate whether such an in vivo disposition pattern is consistent with an earlier and stronger promotion of wound healing events.

Monoclonal anti-EGFreceptor antibody (ior-R3) pharmacokinetic study in tumor bearing nude mice: role of the receptor-mediated endocytosis on drug clearance.

With the purpose of describing the MAb ior-R3's kinetic behavior in disease state, this paper is focused on the study of this response using a human cancer (lung carcinoma cell line, H125) bearing nude mice animal model. This MAb was administered by a single 16 mg/Kg intravenous bolus dose and the blood samples were collected at several times ranging from 0 to 72 hours for serum drug quantification. The experimental data set was best fitted using a classical two-compartment mammilary pharmacokinetic (PK) model and the corresponding PK parameters were determined. Comparatively, the analysis of the more relevant physiologically-based PK parameters showed a significant enhancing of clearance as compound with the earlier reported study on healthy mice, increasing from 0.09 to 0.19 mL/h (p<0.01). However, the corresponding distribution volumes don't seem to be altered by the tumor xenograft. We conclude that all of these evidences suggest a possible mechanism of receptor-mediated endocytosis (RME) as a major cause of this increased drug clearance which also contributed to the faster decrease of the drug disposition.

Disposition and receptor-site binding of (125)I-EGF after topical administration to skin wounds.

The rhEGF topical delivery systems have been hindered by a number of shortcomings which have led to the search of new development strategies. In this study we report the evaluation of cumulative profiles of 10, 5 and 1 microg/ml solutions of (125)I-rhEGF, in a rat full-thickness skin wound model, as well as the drug-induced modulation in the expression of the EGF receptor after lesion. The tissue-associated radioactivity, expressed as the percentage of the dose administered per grams of tissue (%D/g), peaks at 2 h after administration of all doses. (125)I-rhEGF degraded species were detected chromatographically, but no diffusion of the peptide to the surrounding skin was documented. Despite the dose, the EGF receptor expression was increased within 2 h after wounding, followed by a slow decline up to 12 h below baseline. Twelve hours after punch, differences were evident between all treated groups and control. These results demonstrate that (125)I-rhEGF saline solutions are rapidly cleared from application sites, probably by protease-driven cleavage and receptor-mediated endocytosis. Finally, we must be aware that the results herein discussed should be taken into account during the drug delivery system design in order to guarantee the necessary steady-state rhEGF levels upon wound healing process.

Monoclonal anti-epidermal growth factor receptor (ior EGF/r3) antibody pharmacokinetic studies on nude mice I: a radio-receptor analysis applied to drug serum quantification.

Due to its antagonistic properties upon ligand-epidermal growth factor receptor (EGFr) interaction, the monoclonal antibody anti-EGFr ior EGF/r3 is considered a potential therapeutic agent against several epithelium-derived tumours. This paper affords further analysis of the relevant corporal interaction of this monoclonal antibody in terms of its pharmacodynamic properties, using nude mice, following a single bolus intravenous dose administration. The radio-receptor assay allows quantification of the serum ior EGF/r3 level. The dose selection procedure, according to the Kolmogorov-Smirnov test, suggested using doses of 12.5-16 mg kg(-1) for pharmacokinetic assessments. The experimental data were best fitted to a bi-exponential function (r2 = 0.985), through the classical two-compartment open modelling approach. The model selection was corroborated by the AKAIKE information criteria, and also the SCHWARTZ and ESTRIP test were used. The estimated pharmacokinetic parameters (e.g. t 1/2 beta = 34.65 h, Vc = 2.84 mL, Vss = 4.21 mL and CL = 0.09 mL h(-1)) bear out the strategies for the evaluation of the therapeutic application of this drug. Finally, the radio-receptor analysis has provided a rationale for the proposed serum monoclonal antibody ior EGF/r3 quantification to characterize its concentration-time course.

Humanized versus murine anti-human epidermal growth factor receptor monoclonal antibodies for immunoscintigraphic studies.

The anti-human epidermal growth factor receptor (EGF-R) humanized antibody h-R3 (IgG(1)), which binds to an extracellular domain of EGF-R, was used to evaluate the biodistribution on nude mice xenografted with A431 epidermoid carcinoma cell line. Results are compared with its murine version ior egf/r3 monoclonal antibody (mAb). Twenty-one athymic female 4NMRI nu/nu mice were injected intravenously with 10 microg/100 microCi of (99m)Tc-labeled mAbs. The mAb ior C5 that recognizes an antigen expressed preferentially on the surface of malignant and cytoplasm of normal colorectal cells was used as negative control. Immunoreactivity of (99m)Tc-labeled mAbs was measured by enzyme linked immunosorbent assay on A431 cell line and the immunoreactive fractions determined by Lindmo method. Among all organs significative accumulation was found in tumor (6.14 +/- 2.50 %ID/g, 5.06 +/- 2.61 %ID/g for murine and humanized mAbs, respectively) 4 h after injection. The immunoreactive fractions were found to be 0.88 and 0.81 for murine and humanized mAb, respectively. Thus, we expect better results using the humanized mAb h-R3 for diagnostic immunoscintigraphy.

Freeze-dried formulation for direct 99mTc-labeling ior-egf/r3 MAb: additives, biodistribution, and stability.

Monoclonal antibodies (MAbs) have been useful for immunoscintigraphic applications in clinical diagnosis since they were introduced in nuclear medicine practice. The MAb ior egf/r3 developed at the Center of Molecular Immunology (Havana, Cuba) is a murine antibody that recognizes the human epidermal growth factor receptor (EGF-R) and has been used widely in the radioimmunodiagnosis of tumors of epithelial origin. Based on the direct Schwarz method, the present report describes the preparation of a freeze-dried formulation for radiolabeling the MAb ior egf/r3 with 99mTc for immunoscintigraphic applications. Radiolabeling efficiency, effects on immunoreactivity, biodistribution, pharmacokinetic, and stability of the formulation are reported. The study demonstrated that the freeze-dried formulation can be labeled with 99mTc at high yield. The resulting 99mTc-labeled ior egf/r3 MAb can be used to visualize in vivo human tumors of epithelial origin by immunoscintigraphy studies. The kit does not need any other addition or purification at the time of tagging other than the requisite amount of pertechnetate (40-50 mCi). Because the contents of the kit are lyophilized, no special storage or transportation is required.

Biodistribution of 99mTc-labeled anti-human epidermal growth factor receptor (EGF-R) humanized monoclonal antibody h-R3 in a xenograft model of human lung adenocarcinoma.

The anti-human epidermal growth factor receptor (EGF-R) humanized monoclonal antibody (MAb) h-R3 is an (IgG1), which binds to an extracellular domain of EGF-R. It was used to evaluate the biodistribution on nude mice xenografted with H-125 human lung adenocarcinoma cell line. Results were compared with its murine version of the MAb ior-egf/r3. Twenty-one athymic female 4NMRI nu/nu mice were injected intraperitoneally with 10 microg/100 muCi of 99mTc-labeled MAbs. Immunoreactivity of 99mTc-labeled MAbs were measured by enzyme-linked immunosorbent assay (ELISA) on H-125 cell line and the immunoreactive fractions was determined by the Lindmo method. Among all organs, significant accumulation was found in serum (27.05 +/- 2.08 %ID/g) and tumor (3.903 +/- 0.89 %ID/g) at 4 h after injection. These values decreased to 5.03 +/- 0.50 %ID/g and 2.19 +/- 0.56 %ID/g for serum and tumor, respectively. The immunoreactive fraction was found to be 0.70, with a correlation coefficient r = 0.9984. With the good biodistribution and tumor uptake of the 99mTc-labeled humanized antibody h-R3, a phase I diagnostic clinical trial of tumor with epithelial origin should be pursued.

Pharmacokinetics, biodistribution and dosimetry of 99mTc-labeled anti-human epidermal growth factor receptor humanized monoclonal antibody R3 in rats.

The pharmacokinetics, biodistribution and dosimetry of 99mTc-labeled anti-human epidermal growth factor receptor (anti-hEGF-r) humanized monoclonal antibody (MAb) R3 was investigated following intravenous injection in normal Wistar rats. Serum disappearance curves were best fit by a two-compartment model having a mean distribution half-life (t 1/2alpha) of 0.250 h and a mean elimination (t 1/2beta) of 13.89 h. Among the various organs, a little accumulation of the radiolabeled antibody was found only in kidneys. Biodistribution and dosimetry studies in humans were performed by extrapolation of the animal data to humans. Absorbed dose to normal organs and the remainder of the whole body were estimated using the medical internal radiation dose formula, and dose contributions from radioactivity in transit through the gastrointestinal tract were estimated using a compartment model. Extrapolated values of radiation absorbed dose to normal organs in rads per millicurie administered were whole body, 0.0085; lower large intestine wall, 0.0898; small intestine, 0.0530; upper large intestine wall, 0.0731; and kidneys, 0.0455. The effective dose equivalent predicted was 0.0162 rem/mCi and the effective dose was found to be 0.015 rem/mCi. On the basis of the pharmacokinetics, biodistribution and internal radiation dosimetry information obtained in this study, a diagnostic phase I clinical trial with 99mTc-labeled humanized MAb R3 conjugate in patients should be supported.