<Emphasis Type="Italic">In Vivo</Emphasis> Toxicity and Immunological Characterization of Detoxified Recombinant Botulinum Neurotoxin Type A

Purpose

A double-mutant E224A/E262A full-length botulinum neurotoxin (BoNT) Type A with structural similarity to native BoNT/A but lacking the endopeptidase activity provides an ideal surrogate for testing pharmacokinetics and immunochemical characteristics of BoNT.

Methods

We determined lethality (LD₅₀) of deactivated recombinant botulinum neurotoxin (drBoNT/A) to be 24.0 μg by intraperitoneal route (i.p). The polypeptide drBoNT/A labeled with near infra-red dye 800 (NIR 800) was used to examine its distribution to different organs using whole body imaging when administered to mice via intravenous (i.v) or i.p route. Also, drBoNT/A was used to evaluate its immunogenicity in Balb/C mice model.

Results

drBoNT/A was found to be highly immunogenic when tested under various in vivo conditions in Balb/C mice model. For the first time we have demonstrated that a full length 150 kDa drBoNT/A, by administering via inhalation route in mice model, has evoked both circulating immunoglobulin levels of IgG and secretory IgA at the mucosal surface. The immunoglobulin levels were sufficient enough to protect against the challenge dose of native BoNT toxin in mice model. Tissue distribution of drBoNT/A seems to be similar to that of native toxin.

Conclusions

Based on the characteristics described in this report this nontoxic holotoxin protein will assist us to explore the window of opportunity available for therapeutic treatment in case of unnatural poisoning, and also it can be an effective vaccine candidate.

     

SGLT1 inhibition boon or bane for diabetes-associated cardiomyopathy

Chronic hyperglycaemia is a peculiar feature of diabetes mellitus (DM). Sequential metabolic abnormalities accompanying glucotoxicity are some of its implications. Glucotoxicity most likely corresponds to the vascular intricacy and metabolic alterations, such as increased oxidation of free fatty acids and reduced glucose oxidation. More than half of those with diabetes also develop cardiac abnormalities due to unknown causes, posing a major threat to the currently available marketed preparations which are being used for treating these cardiac complications. Even though impairment in cardiac functioning is the principal cause of death in individuals with type 2 diabetes (T2D), reducing plasma glucose levels has little effect on cardiovascular disease (CVD) risk. In vitro and in vivo studies have demonstrated that inhibitors of sodium glucose transporter (SGLT) represent a putative therapeutic intervention for these pathological conditions. Several clinical trials have reported the efficacy of SGLT inhibitors as a novel and potent antidiabetic agent which along with its antihyperglycaemic activity possesses the potential of effectively treating its associated cardiac abnormalities. Thus, hereby, the present review highlights the role of SGLT inhibitors as a successful drug candidate for correcting the shifts in deregulation of cardiac energy substrate metabolism together with its role in treating diabetes-related cardiac perturbations.     

Utility of B-type natriuretic peptide in predicting medium-term mortality in patients undergoing major non-cardiac surgery

This study was conducted to assess the ability of preoperative B-type natriuretic peptide levels to predict medium-term mortality in patients who undergo major noncardiac surgery. During a median of 654 days of follow-up, 33 patients from a total cohort of 204 patients (16%) died, 17 from cardiovascular causes. The optimal cutoff in this cohort, determined using a receiver-operating characteristic curve, was >35 pg . ml(-1). This was associated with a 3.5-fold increase in the hazard of death (p = 0.001) and a 6.9-fold increase in the hazard of cardiovascular mortality (p = 0.003). In conclusion, these findings extend recent work demonstrating that B-type natriuretic peptide levels obtained before major noncardiac surgery can be used to predict perioperative morbidity and indicate that they also forecast medium-term mortality, particularly cardiovascular death.     

Estimation of noise level and signal to noise ratio of laplacian electrocardiogram during ventricular depolarization and repolarization

Body surface Laplacian ECG (LECG) has demonstrated its enhanced capability to localize cardiac electrical sources closest to the recording site. The aim of the present study was to evaluate the noise level and signal to noise ratio (SNR) in the LECG as compared to the potential ECG (PECG). Such evaluation is important to determine the applicability of the LECG to localizing and imaging of cardiac electrical activity in an experimental setting. Experimental studies were conducted in six healthy men. A 150-channel PECG was recorded from the anterolateral chest and the LECG was estimated using the finite difference algorithm. The noise level in the PECG and LECG was evaluated using multiple estimation protocols. The signal level during ventricular depolarization and repolarization was also estimated, and the corresponding SNR was calculated. Different filtering techniques were examined to evaluate their effects on the noise level and SNR of the LECG and PECG. The experimental results indicate that with basic signal processing techniques (baseline adjustment, three-point moving average filter, and Wiener spatial filter), the SNR of the LECG is about 30-40% of that of the PECG. Furthermore, the SNR estimated during ventricular depolarization is about three times that obtained during ventricular repolarization for the PECG and LECG. The present study indicates that the LECG derived from the PECG using a local finite difference estimation procedure has satisfactory SNR during the periods of ventricular depolarization and repolarization, and suggests the feasibility of estimating the LECG from the recorded PECG in human subjects in an experimental setting.     

Saxagliptin added to a submaximal dose of sulphonylurea improves glycaemic control compared with uptitration of sulphonylurea in patients with type 2 diabetes: a randomised controlled trial

Aims: Assess the efficacy and safety of saxagliptin added to a submaximal sulphonylurea dose vs. uptitration of sulphonylurea monotherapy in patients with type 2 diabetes and inadequate glycaemic control with sulphonylurea monotherapy. Methods and patients: A total of 768 patients (18–77 years; HbA_1c screening ≥ 7.5 to ≤ 10.0%) were randomised and treated with saxagliptin 2.5 or 5 mg in combination with glyburide 7.5 mg vs. glyburide 10 mg for 24 weeks. Blinded uptitration glyburide was allowed in the glyburide‐only arm to a maximum total daily dose of 15 mg. Efficacy analyses were performed using ANCOVA and last‐observation‐carried‐forward methodology. Results: At week 24, 92% of glyburide‐only patients were uptitrated to a total glyburide dose of 15 mg/day. Saxagliptin 2.5 and 5 mg provided statistically significant adjusted mean decreases from baseline to week 24 vs. uptitrated glyburide, respectively, in HbA_1c (?0.54%, ?0.64% vs. +0.08%; both p < 0.0001) and fasting plasma glucose (?7, ?10 vs. +1 mg/dl; p = 0.0218 and p = 0.002). The proportion of patients achieving an HbA_1c < 7% was greater for saxagliptin 2.5 and 5 mg vs. uptitrated glyburide (22.4% and 22.8% vs. 9.1%; both p < 0.0001). Postprandial glucose area under the curve was reduced for saxagliptin 2.5 and 5 mg vs. uptitrated glyburide (?4296 and ?5000 vs. +1196 mg·min/dl; both p < 0.0001). Adverse event occurrence was similar across all groups. Reported hypoglycaemic events were not statistically significantly different for saxagliptin 2.5 (13.3%) and 5 mg (14.6%) vs. uptitrated glyburide (10.1%). Conclusion: Saxagliptin added to submaximal glyburide therapy led to statistically significant improvements vs. uptitration of glyburide alone across key glycaemic parameters and was generally well tolerated.     

Comparison of real-time PCR protocols for differential laboratory diagnosis of amebiasis

Specific identification of Entamoeba spp. in clinical specimens is an important confirmatory diagnostic step in the management of patients who may be infected with Entamoeba histolytica, the species that causes clinical amebiasis. Distinct real-time PCR protocols have recently been published for identification of E. histolytica and differentiation from the morphologically identical nonpathogenic Entamoeba dispar. In this study, we compared three E. histolytica real-time PCR techniques published by December 2004. The limits of detection and efficiency of each real-time PCR assay were determined using DNA extracted from stool samples spiked with serially diluted cultured E. histolytica trophozoites. The ability of each assay to correctly distinguish E. histolytica from E. dispar was evaluated with DNA extracted from patients' stools and liver aspirates submitted for confirmatory diagnosis. Real-time PCR allowed quantitative analysis of the spiked stool samples, but major differences in detection limits and assay performance were observed among the evaluated tests. These results illustrate the usefulness of comparative evaluations of diagnostic assays.     

Differential PsaA-, PspA-, PspC-, and PdB-specific immune responses in a mouse model of pneumococcal carriage

Larger numbers of pneumococci were detected in the nasal tract compared to the lung, cervical lymph nodes, and spleen 1, 2, 4, 7, 14, and 21 days after nasal challenge with Streptococcus pneumoniae strain EF3030. In this mouse model of pneumococcal carriage, peripheral S. pneumoniae pneumococcal surface adhesin A (PsaA)-specific humoral responses (immunoglobulin G2a [IgG2a] > IgG1 = IgG2b > IgG3) were significantly higher than pneumococcal surface protein A (PspA)-specific, genetic toxoid derivative of pneumolysin (PdB)-specific, or pneumococcal surface protein C (PspC)-specific serum antibody levels. However, PspA-specific mucosal IgA antibody levels were significantly higher than those against PsaA, PdB, and PspC. In general, both PsaA- and PspA-specific lung-, cervical lymph node-, nasal tract-, and spleen-derived CD4(+) T-cell cytokine (interleukin-4, interleukin-6, granulocyte-macrophage colony-stimulating factor, gamma interferon, and tumor necrosis factor alpha) and proliferative responses were higher than those for either PspC or PdB. Taken together, these findings suggest that PsaA- and PspA-specific mucosal responses as well as systemic humoral and T helper cell cytokine responses are predominantly yet differentially induced during pneumococcal carriage.     

Precipitation of nanohydroxyapatite on PLLA/PBLG/Collagen nanofibrous structures for the differentiation of adipose derived stem cells to osteogenic lineage

Tissue engineering and nanotechnology have enabled engineering of nanostructured materials to meet the current challenges in bone treatment owing to rising occurrence of bone diseases, accidental damages and defects. Poly(l-lactic acid)/Poly-benzyl-l-glutamate/Collagen (PLLA/PBLG/Col) scaffolds were fabricated by electrospinning and nanohydroxyapatite (n-HA) was deposited by calcium-phosphate dipping method for bone tissue engineering (BTE). The abundance and accessibility of adipose derived stem cells (ADSC) may prove to be novel cell therapeutics for bone repair and regeneration. ADSCs were cultured on these scaffolds and were induced to undergo osteogenic differentiation in the presence of PBLG/n-HA for BTE. The cell-biomaterial interactions were analyzed using cell proliferation, SEM and CMFDA dye extraction techniques. Osteogenic differentiation of ADSC was confirmed using alkaline phosphatase activity (ALP), mineralization (ARS) and dual immunofluorescent staining using both ADSC marker protein and Osteocalcin, which is a bone specific protein. The utmost significance of this study is the bioactive PBLG/n-HA biomolecule introduced on the polymeric nanofibers to regulate and improve specific biological functions like adhesion, proliferation and differentiation of ADSC into osteogenic lineage. This was evident from the immunostaining and CMFDA images of ADSCs showing cuboidal morphology, characteristic of osteogenic lineage. The observed results proved that the PLLA/PBLG/Col/n-HA scaffolds promoted greater osteogenic differentiation of ADSC as evident from the enzyme activity and mineralization profiles for bone tissue engineering.