Antibodies recognizing Mycobacterium avium paratuberculosis epitopes cross-react with the beta-cell antigen ZnT8 in Sardinian type 1 diabetic patients

The environmental factors at play in the pathogenesis of type 1 diabetes (T1D) remain enigmatic. Mycobacterium avium subspecies paratuberculosis (MAP) is transmitted from dairy herds to humans through food contamination. MAP causes an asymptomatic infection that is highly prevalent in Sardinian T1D patients compared with type 2 diabetes (T2D) and healthy controls. Moreover, MAP elicits humoral responses against several mycobacterial proteins. We asked whether antibodies (Abs) against one of these proteins, namely MAP3865c, which displays a sequence homology with the β-cell protein zinc transporter 8 (ZnT8) could be cross-reactive with ZnT8 epitopes. To this end, Ab responses against MAP3865c were analyzed in Sardinian T1D, T2D and healthy subjects using an enzymatic immunoassay. Abs against MAP3865c recognized two immunodominant transmembrane epitopes in 52-65% of T1D patients, but only in 5-7% of T2D and 3-5% of healthy controls. There was a linear correlation between titers of anti-MAP3865c and anti-ZnT8 Abs targeting these two homologous epitopes, and pre-incubation of sera with ZnT8 epitope peptides blocked binding to the corresponding MAP3865c peptides. These results demonstrate that Abs recognizing MAP3865c epitopes cross-react with ZnT8, possibly underlying a molecular mimicry mechanism, which may precipitate T1D in MAP-infected individuals.     

Recognition of Zinc Transporter 8 and MAP3865c Homologous Epitopes by Hashimoto's Thyroiditis Subjects from Sardinia: A Common Target with Type 1 Diabetes?

Mycobacterium avium subspecies paratuberculosis (MAP) asymptomatic infection has been previously linked to Type 1 diabetes (T1D) and Multiple Sclerosis. An association between MAP infection and Hashimoto''s thyroiditis (HT) was also proposed only in a case report. This study aimed to investigate the robustness of the latter association, testing a large cohort of HT and healthy control (HCs) subjects, all from Sardinia. Prevalence of anti-MAP3865c Abs was assessed by indirect enzyme-linked immunosorbent assay (ELISA). Moreover, given that human ZnT8 is specifically expressed in the pancreatic β-cells, in the follicle epithelial cells and in the parafollicular cells of the thyroid gland, we also tested ZnT8 epitopes homologues to the MAP3865c immunodominant peptides previously identified. Indeed, Abs targeting MAP3865c and ZnT8 homologous regions display similar frequencies in patients and controls, thus suggesting that Abs recognizing these epitopes could be cross-reactive. A statistically significant difference was found between HT patients and HCs when analyzing the humoral response mounted against MAP3865c/ZnT8 homologues epitopes. To our knowledge, this is the first report, which provides statistically significant evidence sustaining the existence of an association between MAP sero-reactivity and HT. Further studies are required to investigate the relevance of MAP to HT, aimed at deciphering if this pathogen can be at play in triggering this autoimmune disease. Likewise, genetic polymorphism of the host, and other environmental factors need to be investigated.     

Detection of Serum Antibodies Cross-Reacting with Mycobacterium avium Subspecies paratuberculosis and Beta-Cell Antigen Zinc Transporter 8 Homologous Peptides in Patients with High-Risk Proliferative Diabetic Retinopathy

Purpose

MAP3865c, a Mycobacterium avium subspecies paratuberculosis (MAP) cell membrane protein, has a relevant sequence homology with zinc transporter 8 (ZnT8), a beta-cell membrane protein involved in Zn++ transportation. Recently, antibodies recognizing MAP3865c epitopes have been shown to cross-react with ZnT8 in type 1 diabetes patients. The purpose of this study was to detect antibodies against MAP3865c peptides in patients with high-risk proliferative diabetic retinopathy and speculate on whether they may somehow be involved in the pathogenesis of this severe retinal disorder.

Methods

Blood samples were obtained from 62 type 1 and 80 type 2 diabetes patients with high-risk proliferative diabetic retinopathy and 81 healthy controls. Antibodies against 6 highly immunogenic MAP3865c peptides were detected by indirect ELISA.

Results

Type 1 diabetes patients had significantly higher rates of positive antibodies than controls. Conversely, no statistically significant differences were found between type 2 diabetes patients and controls. After categorization of type 1 diabetes patients into two groups, one with positive, the other with negative antibodies, we found that they had similar mean visual acuity (∼0.6) and identical rates of vitreous hemorrhage (28.6%). Conversely, Hashimoto''s thyroiditis prevalence was 4/13 (30.7%) in the positive antibody group and 1/49 (2%) in the negative antibody group, a statistically significant difference (P = 0.016).

Conclusions

This study confirmed that type 1 diabetes patients have significantly higher rates of positive antibodies against MAP/ZnT8 peptides, but failed to find a correlation between the presence of these antibodies and the severity degree of high-risk proliferative diabetic retinopathy. The significantly higher prevalence of Hashimoto''s disease among type 1 diabetes patients with positive antibodies might suggest a possible common environmental trigger for these conditions.     

Screening and identification of human ZnT8-specific single-chain variable fragment (scFv) from type 1 diabetes phage display library

Zinc transporter 8(ZnT8) is a major autoantigen and a predictive marker in type 1 diabetes(T1D). To investigate ZnT8-specific antibodies, a phage display library from T1 D was constructed and single-chain antibodies against ZnT 8 were screened and identified. Human T1 D single-chain variable fragment(sc Fv) phage display library consists of approximately 1í10~8 clones. After four rounds of bio-panning, seven unique clones were positive by phage ELISA. Among them, C27 and C22, which demonstrated the highest affinity to ZnT8, were expressed in Escherichia coli Top10F' and then purified by affinity chromatography. C27 and C22 specifically bound ZnT8 N/C fusion protein and ZnT8 C terminal dimer with one Arg325 Trp mutation. The specificity to human islet cells of these sc Fvs were further confirmed by immunohistochemistry. In conclusion, we have successfully constructed a T1 D phage display antibody library and identified two ZnT8-specific sc Fv clones, C27 and C22. These ZnT8-specific sc Fvs are potential agents in immunodiagnostic and immunotherapy of T1 D.     

Anti-HmuY Antibodies Specifically Recognize Porphyromonas gingivalis HmuY Protein but Not Homologous Proteins in Other Periodontopathogens

Given the emerging evidence of an association between periodontal infections and systemic conditions, the search for specific methods to detect the presence of P. gingivalis, a principal etiologic agent in chronic periodontitis, is of high importance. The aim of this study was to characterize antibodies raised against purified P. gingivalis HmuY protein and selected epitopes of the HmuY molecule. Since other periodontopathogens produce homologs of HmuY, we also aimed to characterize responses of antibodies raised against the HmuY protein or its epitopes to the closest homologous proteins from Prevotella intermedia and Tannerella forsythia. Rabbits were immunized with purified HmuY protein or three synthetic, KLH-conjugated peptides, derived from the P. gingivalis HmuY protein. The reactivity of anti-HmuY antibodies with purified proteins or bacteria was determined using Western blotting and ELISA assay. First, we found homologs of P. gingivalis HmuY in P. intermedia (PinO and PinA proteins) and T. forsythia (Tfo protein) and identified corrected nucleotide and amino acid sequences of Tfo. All proteins were overexpressed in E. coli and purified using ion-exchange chromatography, hydrophobic chromatography and gel filtration. We demonstrated that antibodies raised against P. gingivalis HmuY are highly specific to purified HmuY protein and HmuY attached to P. gingivalis cells. No reactivity between P. intermedia and T. forsythia or between purified HmuY homologs from these bacteria and anti-HmuY antibodies was detected. The results obtained in this study demonstrate that P. gingivalis HmuY protein may serve as an antigen for specific determination of serum antibodies raised against this bacterium.     

Searching for New Clues about the Molecular Cause of Endomyocardial Fibrosis by Way of In Silico Proteomics and Analytical Chemistry

Background

Endomyocardial Fibrosis (EMF) –is a chronic inflammatory disease of the heart with related pathology to that of late stage Chaga''s disease. Indeed, both diseases are thought to result from auto-immune responses against myocardial tissue. As is the case that molecular mimicry between the acidic termini of Trypanosoma cruzi ribosomal P0, P1 and P2β (or simply TcP0, TcP1, and TcP2β) proteins and myocardial tissue causes Chaga''s disease, excessive exposure to certain infections, toxins including cassava ones, allergy and malnutrition has been suggested as the possible cause for EMF. Recent studies have defined the proteomic characteristics of the T. cruzi ribosomal P protein-C-termini involved in mediating auto-immunity against Beta1-adrenergic receptors of the heart in Chaga''s disease. This study aimed to investigate the similarity of C-termini of TcP0/TcP2β to sequences and molecules of several plants, microbial, viral and chemical elements- most prior thought to be possible causative agents for EMF.

Methods and Principal Findings

Comparative Sequence alignments and phylogeny using the BLAST-P tool at the Swiss Institute of Biotechnology (SIB) revealed homologs of C-termini of TcP0 and TcP2β among related proteins from several eukaryotes including the animals (Homo sapiens, C. elegans, D. melanogaster), plants (Arabidopsis thaliana, Zea mays, Glycina Max, Oryza sativa, Rhizopus oryzae) and protozoa (P. falciparum, T. gondii, Leishmania spp).The chemical formulae of the two T.cruzi ribosomal protein C-terminal peptides were found to be C₆₁H₈₃N₁₃O₂₆S₁and C₆₄H₈₇N₁₃O₂₈S₁ respectively by Protparam. Both peptides are heavily negatively charged. Constitutively, both auto-antigens predominantly contain Asparagine (D), Glycine (G) and Phenylamine (F), with a balanced Leucine (L) and Methionine (M) percent composition of 7.7%. The afore going composition, found to be non-homologous to all molecules of chemical species in the databases searched, suggests the possible role of a metabolic pathway in the pathogenesis of EMF if aligned with our “molecular mimicry” hypothesis.

Conclusions

Our findings provide a “window” to suggest that cross reactivity of antibodies against C-terminal sequences of several animal, plant and protozoal ribosomal P proteins with heart tissue may mediate EMF in a similar manner as C- termini of T. cruzi do for Chaga''s disease.     

Pancreatic B-cells secrete a range of novel peptides besides insulin

Insulin secretion by a transplantable rat islet B-cell tumour is accompanied by the release of two putative proinsulin cleavage intermediates, four peptides of M_r 9000–12 000 (excluding proinsulin) and peptides of M_r 21 000, 34 000 and 60 000. Granule-enriched subcellular preparations contain major peptides of identical M_r values. Of these peptides seven at least coincide in molecular weight with peptides secreted by isolated rat islets and thus may be constituents of the normal insulin secretory granule.     

ZnT7 can protect MC3T3-E1 cells from oxidative stress-induced apoptosis via PI3K/Akt and MAPK/ERK signaling pathways

The osteoblasts could be lead to the occurrence of apoptosis by oxidative stress. The zinc transporter family SLC30A (ZnTs) plays an important role in the regulation of zinc homeostasis, however, its function in apoptosis of MC3T3-E1 cells remains unknown. This study was aimed to investigate the role of zinc transporters in cell survival, particularly in MC3T3-E1 cells, during oxidative stress, and the molecular mechanism involved. Our study found that hydrogen peroxide can induce zinc-overloaded in the cells. While high concentration of zinc plays an important role in inducing apoptosis of the MC3T3-E1 cells, we demonstrated that ZnT7 can protect MC3T3-E1 cells and reduce the aggregation of intracellular free zinc ions as well as inhibit apoptosis induced by H₂O₂. Moreover, ZnT7 overexpression enhanced the anti-apoptotic effects. Interestingly, suppression of ZnT7 by siRNA could significantly exacerbate apoptosis in MC3T3-E1 cells. We also found that ZnT7 promotes cell survival via two distinct signaling pathways involving activation of the PI3K/Akt-mediated survival pathway and activation of MAPK/ERK pathway. Collectively, these results suggest that ZnT7 overexpression significantly protects osteoblasts cells from apoptosis induced by H₂O₂. This effect is mediated, at least in part, through activation of PI3K/Akt and MAPK/ERK pathways.     

DNA binding mode of the Fab fragment of a monoclonal antibody specific for cyclobutane pyrimidine dimer

Monoclonal antibodies specific for the cyclobutane pyrimidine dimer (CPD) are widely used for detection and quantification of DNA photolesions. However, the mechanisms of antigen binding by anti-CPD antibodies are little understood. Here we report NMR analyses of antigen recognition by TDM-2, which is a mouse monoclonal antibody specific for the cis-syn-cyclobutane thymine dimer (T[c,s]T). ³¹P NMR and surface plasmon resonance data indicated that the epitope recognized by TDM-2 comprises hexadeoxynucleotides centered on the CPD. Chemical shift perturbations observed for TDM-2 Fab upon binding to d(T[c,s]T) and d(TAT[c,s]TAT) were examined in order to identify the binding sites for these antigen analogs. It was revealed that d(T[c,s]T) binds to the central part of the antibody-combining site, while the CPD-flanking nucleotides bind to the positively charged area of the V_H domain via electrostatic interactions. By applying a novel NMR method utilizing a pair of spin-labeled DNA analogs, the orientation of DNA with respect to the antigen-binding site was determined: CPD-containing oligonucleotides bind to TDM-2 in a crooked form, draping the 3′-side of the nucleotides onto the H1 and H3 segments, with the 5′-side on the H2 and L3 segments. These data provide valuable information for antibody engineering of TDM-2.     

Reduced Risk of Hypoglycemia with Insulin Degludec Versus Insulin Glargine in Patients with Type 2 Diabetes Requiring High Doses of Basal Insulin: A Meta-Analysis of 5 Randomized Begin Trials

ObjectiveThis meta-analysis of 5 trials from the Phase 3a insulin degludec (IDeg) clinical trial program evaluated the risk of hypoglycemia in a subset of subjects with type 2 diabetes (T2D) who required high basal insulin doses at the end of the trials.MethodsThis meta-analysis compared glycated hemoglobin (HbA_1c), fasting plasma glucose (FPG), basal insulin dose, body weight, and rates of overall and nocturnal confirmed hypoglycemia in a pooled population of T2D subjects using > 60 U basal insulin at trial completion. Five Phase 3a, open-label, randomized, treat-to-target, confirmatory 26-or 52-week trials with IDeg (n = 2,262) versus insulin glargine (IGlar) (n = 1,110) administered once daily were included. Overall confirmed hypoglycemia was defined as self-measured blood glucose < 56 mg/dL or any episode requiring assistance; nocturnal confirmed hypoglycemia had an onset between 00:01 and 05:59 am.ResultsMore than one-third of IDeg-(35%) and IGlar-(34%) treated T2D subjects required > 60 U of basal insulin daily at the ends of the trial. Patients achieved similar mean HbA_1c values (estimated treatment difference [ETD] IDeg - IGlar: 0.05%, P = .44) while mean FPG values were lower with IDeg than IGlar (ETD: - 5.9 mg/ dL, P = .04) at end-of-trial. There was a 21% lower rate of overall confirmed hypoglycemic episodes for IDeg (estimated rate ratio [RR] IDeg/IGlar: 0.79, P = .02) and a 52% lower rate of nocturnal confirmed hypoglycemic episodes for IDeg (RR: 0.48, P < .01).ConclusionIn this post hoc meta-analysis, more than 30% of subjects with T2D required > 60 U/day of basal insulin at the end of the trials. In these individuals, IDeg achieves similar HbA_1c reduction with significantly less overall and nocturnal confirmed hypoglycemia compared with IGlar. (Endocr Pract. 2014;20:285-292)     

右美托咪定联合丙泊酚在房颤电复律中的镇静效果研究

摘要 目的：在接受电复律的房颤患者中,观察比较丙泊酚联合右美托咪定和单用丙泊酚镇静的安全性及有效性。方法：2021年1月至2021年10月期间纳入60例接受电复律的房颤患者,根据随机数表法分为观察组（丙泊酚-右美P-D组）和对照组（丙泊酚 P组）,每组30人,观察两组T0-T4不同阶段的生命体征、不良事件、镇痛效果、苏醒时间等指标。结果：P-D组在T1-4时段HR较T0减低,P组T2-4时段HR也较T0下降,但两组间无明显差异。两组在T2、T3时MAP、SpO₂均低于T0,但T2时段P-D组MAP、SpO₂下降幅度低于P组, T3时段SpO₂下降幅度低于P组, MAP降幅无差异。P-D组丙泊酚用量显著低于P组（48.67±15.03 mg vs 71.33±19.03 mg;P<0.001）,但苏醒时间无明显差异。P-D组呼吸抑制、心动过缓的发生率均低于P组（16.7% vs 40% P=0.045;13.3% vs 3.3% P=0.35）。P-D组镇痛评分为轻度以下者占93.3%,显著优于P组的73.3%（P<0.05）。结论：对电复律的房颤患者,丙泊酚-右美托咪定复合策略展现出良好的镇静、镇痛效果,该方案可明显降低丙泊酚用量,减少临床不良事件率,增强了用药安全性。     

The SH3 domain of HS1 protein recognizes lysine-rich polyproline motifs

HS1 is a protein involved in erythroid proliferation and apoptotic cell death, containing several structurally significant motifs including a C-terminal SH3 domain. HPK1 is a member of the Ste20-related kinase family, which contains four proline-rich sequences and is constitutively associated with HS1 in hematopoietic cells. Recombinant fusion protein GST-SH3_HS1 was expressed to assess the binding properties of 16 peptides derived from the HPK1 proline-rich regions. The binding affinities were determined by non-immobilized ligand interaction assay by circular dichroism. Our results revealed that the classical PxxPxK class II binding motif is not sufficient to induce the interaction with the GST-SH3_HS1 domain, an event dependent on the presence of additional basic residue(s) located at the C-terminus of the PxxPxK motif: Lys₋₅ in P2 peptide and Lys₋₈ in P4c peptide. Lys replacement by Arg residues decreases the ligand binding affinity. The finding that both SH3_HS1 domain and full-length HS1 protein bind to P2 peptide with similar affinity demonstrates that the whole protein sequence does not affect the interaction properties of the domain. In silico models of SH3_HS1 as a complex with P2 or P4c highlight the domain residues that interact with the recognition determinants of the peptide ligand and that cooperate in the complex stabilization.     

Human type 1 diabetes is associated with T cell autoimmunity to zinc transporter 8

Recently we demonstrated that zinc transporter 8 (ZnT8) is a major target of autoantibodies in human type 1 diabetes (T1D). Because the molecules recognized by T1D autoantibodies are typically also targets of autoreactive T cells, we reasoned that this would likely be the case for ZnT8. To test this hypothesis, IFN-γ-producing T cells specific for ZnT8 in the peripheral blood of 35 patients with T1D (<6 mo after onset at blood draw) and 41 age-matched controls were assayed by ELISPOT using a library of 23 overlapping dipeptide pools covering the entire 369 aa primary sequence. Consistent with our hypothesis, patients showed significantly higher T cell reactivity than the matched controls, manifest in terms of the breadth of the overall response and the magnitude of responses to individual pools. Therefore, the median number of pools giving positive responses (stimulation index ≥ 3) in the control group was 1.0 (range, 0-7) compared with 6.0 (range, 1-20; p < 0.0001) for the patients. Similarly, the median stimulation index of positive responses in controls was 3.1 versus 5.0 in the patients (p < 0.0001). Individually, 7 of 23 pools showed significant disease association (p < 0.001), with several of the component peptides binding the disease associated HLA-DR3 (0301) and -DR4 (0401) molecules in vitro. We conclude that ZnT8 is also a major target of disease-associated autoreactive T cells in human T1D, and we suggest that reagents that target ZnT8-specific T cells could have therapeutic potential in preventing or arresting the progression of this disease.     

Preserved Proinsulin Production in Homozygous Protein Tyrosine Phosphatase Nonreceptor Type 22 C1858T Variant Type 1 Diabetes: A Possible Explanation for Absence of Overt Ketoacidosis Despite Omission of Exogenous Insulin

ObjectiveTo report a postulated mechanism for resistance to overt ketoacidosis due to prolonged insulin omission in a severely hyperglycemic woman with a 14-year history of autoimmune type 1 diabetes (T1D).MethodsHistory, physical examination, laboratory testing, and genotyping were performed. We also review the medical literature pertinent to this patient’s phenotype and genotype.ResultsProinsulin levels remained within the normal range (suppressed with hypoglycemia) despite simultaneous almost unmeasurable C-peptide levels during hyperglycemia. We confirmed a homozygous (TT) variant of protein tyrosine phosphatase nonreceptor type 22 (PTPN22) 1858T, a T1D susceptibility gene associated with higher proinsulin levels.ConclusionThe extraordinarily preserved proinsulin biological activity may explain the unusual resistance to overt ketoacidosis despite omission of exogenous insulin administration for extended periods of time. The role of the associated PTPN22 1858TT variant remains speculative. (Endocr Pract. 2013;19:426-430)     

Conformation and membrane orientation of amphiphilic helical peptides by oriented circular dichroism

Oriented circular dichroism (OCD) was used to characterize and compare in a quantitative manner the secondary structure and concentration dependent realignment of the antimicrobial peptides PGLa and MSI-103, and of the structurally related cell-penetrating peptide MAP in aligned phospholipid bilayers. All these peptides adopt an amphiphilic α-helical conformation, and from solid-state NMR analysis they are known to bind to membranes in two distinct orientations depending on their concentration. At low peptide/lipid (P/L) ratio the helices are aligned parallel to membrane surface (S-state), but with increasing concentration they realign to a tilted orientation (T-state), getting immersed into the membrane with an oblique angle supposedly as a result of dimer-formation. In macroscopically aligned liquid crystalline 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine bilayers the two limiting states are represented by distinct OCD spectra, and all spectra at intermediate peptide concentrations can be described by a linear combination of these two line shapes. The corresponding fraction of molecules occupying the T-state was determined by fitting the intermediate spectra with a superposition of the two extreme line shapes. By plotting this fraction versus 1/(P/L), the threshold P/L* ratio for realignment was extracted for each of the three related peptides. Despite their structural similarity distinctly different thresholds were obtained, namely for MSI-103 realignment starts already at a low P/L of ∼1:236, for a MAP derivative (using a nonaggregating analog containing a D-amino acid) the transition begins at P/L ∼1:156, whereas PGLa needs the highest concentration to flip into T-state at P/L ∼1:85. Analysis of the original MAP sequence (containing only L-amino acids) gave OCD spectra compatible with β-pleated conformation, suggesting that this peptide starts to aggregate with increasing concentration, unlike the other helical peptides. All these changes in peptide conformation and membrane alignment observed here by OCD seem to be functionally relevant, as they can be correlated with the membrane perturbing activities of the three antimicrobial and cell-penetrating sequences.     

Risk for Coexistent Autoimmune Diseases in Familial and Sporadic Type 1 Diabetes is Related to Age at Diabetes Onset

ObjectiveType 1 diabetes (T1D) is frequently associated with other autoimmune diseases (AIDs). Although most of T1D patients are sporadic cases (S-T1D), 10% to 15% have a familial form (F-T1D) involving 2 or more first-degree relatives. This study evaluated the effect of T1D family aggregation and age onset on AIDs occurrence.MethodsIn this observational, cross-sectional, case-control, single center study, we enrolled 115 F-T1D and 115 S-T1D patients matched for gender, age, T1D age onset, and duration. With respect to T1D age onset (before or after 18 years), both groups were further subdivided into young- or adult-onset F-T1D and young- or adult-onset S-T1D. The presence of organ-specific antibodies and/or overt AIDs was evaluated.ResultsThe F-T1D group had a higher percentage of AIDs (29.8% vs 18.4%, P = .04) and a significant earlier onset of AIDs at Cox regression analysis (P = .04) than the S-T1D group. Based on multivariate analysis, the adult-onset F-T1D subgroup had the highest prevalence of both additional organ-specific antibodies (60.5%) and overt AIDs (34.9%), whereas the adult S-T1D subgroup was the least frequently involved (29.1% and 12.7%, respectively). In F-T1D patients, offsprings develop T1D and AIDs earlier than their parents do.ConclusionsIn T1D patients, familial aggregation and adult-onset of T1D increase the risk for coexistent AIDs. These clinical predictors could guide clinicians to address T1D patients for the screening of T1D-related AIDs.     

Reduced Parathyroid Hormone-Stimulated 1,25-Dihydroxyvitamin D Production in Vitamin D Sufficient Postmenoposual Women with Low Bone Mass and Idiopathic Secondary Hyperparathyroidism

ObjectiveDistinguishing secondary hyperparathyroidism (sHPT) from eucalcemic primary hyperparathyroidism (EC-pHPT) is important. The objective of this study was to measure parathyroid hormone (PTH)-stimulated production of 1α,25-dihydroxyvitamin D (1,25[OH]₂D) in early postmenopausal patients with idiopathic sHPT, who also fit the criteria for EC-pHPT, compared to age-matched controls.MethodsIn this pilot case-control study, postmenopausal women aged 44 to 55 years with normal serum calcium (Ca), glomerular filtration rate (GFR) ≥65 mL/min, and 25-hydroxyvitamin D (25[OH]D) ≥75 nmol/L (30 ng/mL) were given an 8 hour infusion of PTH(1-34), 12 pmol/kg/h. Patients (n = 5) had elevated PTH, normal 1,25(OH)₂D, and no hypercalciuria. Controls (n = 5) had normal PTH. At baseline, 4, and 8 hours, serum Ca, creatinine (Cr), phosphorus (P), 1,25(OH)₂D, fibroblast growth factor (FGF23), and 24,25(OH)₂D as well as urine Ca, P, Cr, and cAMP/GFR were measured. The fractional excretion of calcium (FeCa) and tubular reabsorption of phosphorus (TMP)/GFR were calculated.ResultsPatients had lower 1,25(OH)₂D levels (± SD) than controls at 4 (39.8 ± 6.9 versus 58.8 ± 6.7; P = .002) and 8 hours (56.4 ± 9.2 versus 105 ± 2.3; P = .003) of PTH infusion, attenuated after adjusting for higher body mass index (BMI) in patients (P = .05, .04), respectively. The 24,25(OH)2D levels were lower in patients than controls (1.9 ± 0.6 versus 3.4 ± 0.6, respectively; P = .007). No differences were seen in serum Ca or P, urine cAMP/GFR, TRP/GFR, FeCa, or PTH suppression at 8 hours (patients 50%, controls 64%).ConclusionVitamin D sufficient patients who fit the criteria for EC-pHPT had reduced PTH-stimulated 1,25(OH)₂D compared to controls, partially attributable to their higher BMI. Other causes of reduced 1,25(OH)₂D production ruled out were excessive catabolism of vitamin D metabolites, elevated FGF23, and CYP27B1 mutation. Elevated BMI and idiopathic reduced PTH-stimulated 1,25(OH)₂D production should be considered in the differential of sHPT. (Endocr Pract. 2013;19:91-99)     

Synthesis,In Vitro Biological Stability,and Anti-HIV Activity of 5-Halo (or Methoxy)-6-Alkoxy (Azido or Hydroxy)-5,6-Dihydro-2′,3′-Didehydro-3′-Deoxythymidine Diastereomers as Potential Prodrugs of 2′,3′-Didehydro-3′-deoxythymidine (D4T)

Abstract

A new class of 5-halo (or methoxy)-6-alkoxy (azido or hydroxy)-5,6-dihydro-2′,3′-didehydro-3′-deoxythymidines (4–17) were investigated as potential anti-AIDS drugs. These 5,6-dihydro derivatives, which are also potential prodmgs of 2′,3′-didehydro-3′-deoxythymidine (D4T) were designed to have properties which would enhance their duration of action, lipophilicity and cephalic delivery to the central nervous system. The 5,6-dihydro derivatives of D4T (4–15), which differ in configuration at the C-5 and C-6 positions, were synthesized by the regiospecific addition of XR (X = Br, Cl, I; R = OMe, OEt, N₃, OH) to the 5,6-olefinic bond of D4T. These 5,6-disubstituted-5,6-dihydro analogs of D4T are more lipophilic (P = 0.70 – 4.0 range) than D4T (P = 0.12) and are stable to E. coli thymidine phosphorylase. Regeneration of the 5,6-olefinic bond to give D4T, upon incubation of the 5-bromo- and 5-iodo-6-methoxy-5,6-dihydro derivatives (6, 7, 10, 11) with glutathione or a mouse liver soluble enzyme fraction, was extensive (50–95%). The most potent anti-HIV-1 agents, 5-iodo-6-methoxy (10, 11), 5-bromo-6-azido (14, 15) and 5-methoxy-6-hydroxy (16, 17) derivatives of D4T, exhibited anti-HIV activities comparable to D4T.

     

Molecular characterization of novel immunodominant molybdenum cofactor biosynthesis protein C1 (Rv3111) from Mycobacterium tuberculosis H37Rv

BackgroundIn the molybdenum cofactor biosynthesis pathway, MoaA and MoaC catalyze the first step of transformation of GTP to cPMP. In M. tuberculosis H37Rv, three different genes (Rv3111, Rv0864 and Rv3324c) encode for MoaC homologs. Out of these three only MoaC1 (Rv3111) is secretory in nature.MethodsWe have characterized MoaC1 protein through biophysical, in-silico, and immunological techniques.ResultsWe have characterized the conformation and thermodynamic stability of MoaC1, and have established its secretory nature by demonstrating the presence of anti-MoaC1 antibodies in human tuberculosis patients' sera. Further, MoaC1 elicited a dominant Th1 immune response in mice characterized by increased induction of IL-2 and IFN-γ.ConclusionIntegrating these results, we conclude that MoaC1 is a structured secretory protein capable of binding with GTP and eliciting induced immune response.General significanceThis study would be useful for the development of vaccines against tuberculosis and to improve methods used for diagnosis of tuberculosis.     

Panaxynol induces neurite outgrowth in PC12D cells via cAMP- and MAP kinase-dependent mechanisms

Panaxynol, a polyacetylene ((3R)-heptadeca-1,9-diene-4,6-diyn-3-ol; syn. falcarinol), was isolated from the lipophilic fractions of Panax notoginseng, a Chinese traditional medicinal plant. In the present study, we reported the neurotrophic effects of panaxynol on PC12D cells and mechanism involved in neurite outgrowth of the cells. Panaxynol could morphologically promote neurite outgrowth in PC12D cells, concentration-dependently reduce cell division and up-regulate molecular marker (MAP1B) expression in PC12D cells. Panaxynol induces the elevation of intracellular cAMP in PC12D cells. The neurite outgrowth in PC12D cells induced by panaxynol could be inhibited by the protein kinase A inhibitor RpcAMPS and by MAP kinase kinase 1/2 inhibitor U0126. These observations reveal that panaxynol could induce the differentiation of PC12D cells in a process similar to but distinct from that of NGF and the panaxynol's effects were via cAMP- and MAP kinase-dependent mechanisms.