Klotho and Aminopeptidases as Early Biomarkers of Renal Injury in Zucker Obese Rats

The aim of this study was to investigate if urinary glutamyl aminopeptidase (GluAp), alanyl aminopeptidase (AlaAp), Klotho and hydroxyproline can be considered as potential biomarkers of renal injury and fibrosis in an experimental model of obesity. Male Zucker lean (ZL) and obese (ZO) rats were studied from 2 to 8 months old. Kidneys from ZO rats at the end of the study (8 months old) developed mild focal and segmental glomerulosclerosis as well as moderate tubulointerstitial injury. Urinary excretion of Klotho was higher in ZO rats at 2, 5, and 8 months of study, plasma Klotho levels were reduced and protein abundance of Klotho in renal tissue was similar in ZL and ZO rats. GluAp and AlaAp urinary activities were also increased in ZO rats throughout the time-course study. ZO rats showed an augmentation of hydroxyproline content in renal tissue and a significant increase of tubulointerstitial fibrosis. Correlation studies demonstrated that GluAp, AlaAp, and Klotho are early diagnostic markers of renal lesions in Zucker obese rats. Proteinuria and hydroxyproline can be considered delayed diagnostic markers because their contribution to diagnosis starts later. Another relevant result is that GluAp, AlaAp, and Klotho are related not only with diagnosis but also with prognosis of renal lesions in Zucker obese rats. Moreover, strong predictive correlations of aminopeptidasic activities with the percentage of renal fibrosis or with renal hydroxyproline content at the end of the experiment were observed, indicating that an early increased excretion of these markers is related with a higher later extent of fibrosis in Zucker obese rats. In conclusion, GluAp, AlaAp, and Klotho are early diagnostic markers that are also related with the extent of renal fibrosis in Zucker obese rats. Therefore, they have a potential use not only in diagnosis, but also in prognosis of obesity-associated renal lesions.

Studies on the Substrate Selectivity of the Hypoxia-Inducible Factor Prolyl Hydroxylase 2 Catalytic Domain

In animals, the response to chronic hypoxia is mediated by upregulation of the α,β-heterodimeric hypoxia-inducible factors (HIFs). Levels of HIFα isoforms, but not HIFβ, are regulated by their post-translational modification as catalysed by prolyl hydroxylase domain enzymes (PHDs). Different roles for the human HIF-1/2α isoforms and their two oxygen-dependent degradation domains (ODDs) are proposed. We report kinetic and NMR analyses of the ODD selectivity of the catalytic domain of wild-type PHD2 (which is conserved in nearly all animals) and clinically observed variants. Studies using Ala scanning and "hybrid" ODD peptides imply that the relatively rigid conformation of the (hydroxylated) proline plays an important role in ODD binding. They also reveal differential roles in binding for the residues on the N- and C-terminal sides of the substrate proline. The overall results indicate how the PHDs achieve selectivity for HIFα ODDs and might be of use in identifying substrate-selective PHD inhibitors.

Characterization of Angiotensin-Converting Enzyme Inhibitory Activity of X-Hyp-Gly-Type Tripeptides: Importance of Collagen-Specific Prolyl Hydroxylation

Hydroxyproline (Hyp) is a collagen-specific amino acid formed by post-translational hydroxylation of Pro residues. Various Hyp-containing oligopeptides are transported into the blood at high concentrations after oral ingestion of collagen hydrolysate. Here we investigated the angiotensin-converting enzyme (ACE) inhibitory activity of X-Hyp-Gly-type tripeptides. In an in vitro assay, ginger-degraded collagen hydrolysate enriched with X-Hyp-Gly-type tripeptides dose-dependently inhibited ACE and various synthetic X-Hyp-Gly-type tripeptides showed ACE-inhibitory activity. In particular, strong inhibition was observed for Leu-Hyp-Gly, Ile-Hyp-Gly, and Val-Hyp-Gly with IC₅₀ values of 5.5, 9.4, and 12.8 μM, respectively. Surprisingly, substitution of Hyp with Pro dramatically decreased inhibitory activity of X-Hyp-Gly, indicating that Hyp is important for ACE inhibition. This finding was supported by molecular docking experiments using Leu-Hyp-Gly/Leu-Pro-Gly. We further demonstrated that prolyl hydroxylation significantly enhanced resistance to enzymatic degradation by incubation with mouse plasma. The strong ACE-inhibitory activity and high stability of X-Hyp-Gly-type tripeptides highlight their potential for hypertension control.

Assessment of Wound-Healing Properties of Medicinal Plants: The Case of Phyllanthus muellerianus

Phyllanthus muellerianus (Family Euphorbiaceae) is a shrub, which is widely distributed in West Africa and employed traditionally as a wound-healing agent especially in Ghana. The aim of the study was to determine the in vivo wound-healing activity of aqueous aerial part extract of P. muellerianus (PLE) and its major isolate, geraniin. Excision and incision wound models were used to determine the wound-healing activity. Wounds were treated with PLE (0.25, 0.5, and 1% w/w) and geraniin (0.1, 0.2, and 0.4% w/w) aqueous creams. PLE and geraniin significantly (p < 0.001) increased wound contraction rate and hydroxyproline production compared to untreated wounds. Histological studies of wound tissues showed high levels of fibroblasts and increased collagen content and cross-linking in PLE and geraniin-treated wound tissues. Immuno-histochemical investigations revealed high levels of TGF-β₁ in PLE and geraniin-treated wound tissues compared to the untreated wound tissues. Tensile strength of incised wounds was significantly (p < 0.05) high in PLE and geraniin-treated wounds. PLE (0.1–100 μg/mL) significantly (p < 0.001) reduce LDH release from HaCaT-keratinocytes compared to the untreated cells. PLE and geraniin possess wound healing and cytoprotective effect.

Correlations between Extracellular Matrix Components in Mouse Lungs during Chronic BCG-Induced Granulomatosis

Correlations between extracellular matrix components in mouse lungs were examined during various terms of BCG-induced granulomatosis (on postinfection days 3, 30, 60, 90, and 180). During the development of pathological process, the revealed dynamic interrelations between structural units of proteoglycans and hydroxyproline weakened. Most correlations were observed on postinfection day 180. They reflect the relationships not only between the structural units of proteoglycans but also between collagens, presumably determining the maximum degree of fibrosis at this period. The established correlations characterize the systemic nature of reactions in extracellular matrix and its versatile implications determined by the processes going on in the organs and tissues during the onset and development of generalized pathology.

Reassessing the chronology of the archaeological site of Anzick

Found in 1968, the archaeological site of Anzick, Montana, contains the only known Clovis burial. Here, the partial remains of a male infant, Anzick-1, were found in association with a Clovis assemblage of over 100 lithic and osseous artifacts-all red-stained with ochre. The incomplete, unstained cranium of an unassociated, geologically younger individual, Anzick-2, was also recovered. Previous chronometric work has shown an age difference between Anzick-1 and the Clovis assemblage (represented by dates from two antler rod samples). This discrepancy has led to much speculation, with some discounting Anzick-1 as Clovis. To resolve this issue, we present the results of a comprehensive radiocarbon dating program that utilized different pretreatment methods on osseous material from the site. Through this comparative approach, we obtained a robust chronometric dataset that suggests that Anzick-1 is temporally coeval with the dated antler rods. This implies that the individual is indeed temporally associated with the Clovis assemblage.

Chondrogenic differentiation of human chondrocytes cultured in the absence of ascorbic acid

Bioreactor systems will likely play a key role in establishing regulatory compliant and cost-effective production systems for manufacturing engineered tissue grafts for clinical applications. However, the automation of bioreactor systems could become considerably more complex and costly due to the requirements for additional storage and liquid handling technologies if unstable supplements are added to the culture medium. Ascorbic acid (AA) is a bioactive supplement that is commonly presumed to be essential for the generation of engineered cartilage tissues. However, AA can be rapidly oxidized and degraded. In this work, we addressed whether human nasal chondrocytes can redifferentiate, undergo chondrogenesis, and generate a cartilaginous extracellular matrix when cultured in the absence of AA. We found that when chondrocytes were cultured in 3D micromass pellets either with or without AA, there were no significant differences in their chondrogenic capacity in terms of gene expression or the amount of glycosaminoglycans. Moreover, 3D pellets cultured without AA contained abundant collagen Types II and I extracellular matrix. Although the amounts of Collagens II and I were significantly lower (34% and 50% lower) than in pellets cultured with AA, collagen fibers had similar thicknesses and distributions for both groups, as shown by scanning electron microscopy imaging. Despite the reduced amounts of collagen, if engineered cartilage grafts can be generated with sufficient properties that meet defined quality criteria without the use of unstable supplements such as AA, bioreactor automation requirements can be greatly simplified, thereby facilitating the development of more compact, user-friendly, and cost-effective bioreactor-based manufacturing systems.

Proline hydroxylation in collagen supports integrin binding by two distinct mechanisms

Collagens are the most abundant extracellular matrix proteins in vertebrates and have a characteristic triple-helix structure. Hydroxylation of proline residues is critical for helix stability, and diminished prolyl hydroxylase activity causes wide-spread defects in connective tissues. Still, the role of proline hydroxylation in the binding of collagen receptors such as integrins is unclear. Here, we isolated skin collagen from genetically modified mice having reduced prolyl 4-hydroxylase activity. At room temperature, the reduced proline hydroxylation did not affect interactions with the recombinant integrin α2I domain, but at 37 °C, collagen hydroxylation correlated with the avidity of α2I domain binding. Of note, LC-MS/MS analysis of isolated skin collagens revealed no major changes in the hydroxyproline content of the main integrin-binding sites. Thus, the disrupted α2I domain binding at physiological temperatures was most likely due to structural destabilization of the collagenous helix. Integrin α2I binding to the triple-helical GFPGER motif was slightly weaker than to GFOGER (O = hydroxyproline). This phenomenon was more prominent when α1 integrin was tested. Integrin α1β1 expressed on CHO cells and recombinant α1I domain showed remarkably slower binding velocity and weaker avidity to GFPGER when compared with GFOGER. Structural modeling revealed the critical interaction between Arg-218 in α1I and the hydroxyproline residue in the integrin-binding motif. The role of Arg-218 was further validated by testing a variant R218D α1I domain in solid-phase binding assays. Thus, our results show that the lack of proline hydroxylation in collagen can affect integrin binding by a direct mechanism and via structural destabilization of the triple helix.

Hydroxyproline Metabolism and Oxalate Synthesis in Primary Hyperoxaluria

Background Endogenous oxalate synthesis contributes to calcium oxalate stone disease and is markedly increased in the inherited primary hyperoxaluria (PH) disorders. The incomplete knowledge regarding oxalate synthesis complicates discovery of new treatments. Hydroxyproline (Hyp) metabolism results in the formation of oxalate and glycolate. However, the relative contribution of Hyp metabolism to endogenous oxalate and glycolate synthesis is not known.Methods To define this contribution, we performed primed, continuous, intravenous infusions of the stable isotope [¹⁵N,¹³C₅]-Hyp in nine healthy subjects and 19 individuals with PH and quantified the levels of urinary ¹³C₂-oxalate and ¹³C₂-glycolate formed using ion chromatography coupled to mass detection.Results The total urinary oxalate-to-creatinine ratio during the infusion was 73.1, 70.8, 47.0, and 10.6 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3 and controls, respectively. Hyp metabolism accounted for 12.8, 32.9, and 14.8 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3, respectively, compared with 1.6 mg oxalate/g creatinine in controls. The contribution of Hyp to urinary oxalate was 15% in controls and 18%, 47%, and 33% in subjects with PH1, PH2, and PH3, respectively. The contribution of Hyp to urinary glycolate was 57% in controls, 30% in subjects with PH1, and <13% in subjects with PH2 or PH3.Conclusions Hyp metabolism differs among PH types and is a major source of oxalate synthesis in individuals with PH2 and PH3. In patients with PH1, who have the highest urinary excretion of oxalate, the major sources of oxalate remain to be identified.

iHyd-PseCp: Identify hydroxyproline and hydroxylysine in proteins by incorporating sequence-coupled effects into general PseAAC

Protein hydroxylation is a posttranslational modification (PTM), in which a CH group in Pro (P) or Lys (K) residue has been converted into a COH group, or a hydroxyl group (−OH) is converted into an organic compound. Closely associated with cellular signaling activities, this type of PTM is also involved in some major diseases, such as stomach cancer and lung cancer. Therefore, from the angles of both basic research and drug development, we are facing a challenging problem: for an uncharacterized protein sequence containing many residues of P or K, which ones can be hydroxylated, and which ones cannot? With the explosive growth of protein sequences in the post-genomic age, the problem has become even more urgent. To address such a problem, we have developed a predictor called iHyd-PseCp by incorporating the sequence-coupled information into the general pseudo amino acid composition (PseAAC) and introducing the “Random Forest” algorithm to operate the calculation. Rigorous jackknife tests indicated that the new predictor remarkably outperformed the existing state-of-the-art prediction method for the same purpose. For the convenience of most experimental scientists, a user-friendly web-server for iHyd-PseCp has been established at http://www.jci-bioinfo.cn/iHyd-PseCp, by which users can easily obtain their desired results without the need to go through the complicated mathematical equations involved.

Pyridine 2,4-Dicarboxylic Acid Suppresses Tomato Seedling Growth

Pyridine 2,4-dicarboxylic acid is a structural analog of 2-oxoglutarate and is known to inhibit 2-oxoglutare-dependent dioxygenases. The effect of this inhibitor in tomato seedlings grown in MS media supplied with various concentrations of PDCA was investigated, resulting in shorter roots and hypocotyls in a dose-dependent manner. The partial inhibition of growth in roots was more drastic compared to hypocotyls and was attributed to a decrease in the elongation of root and hypocotyl cells. Concentrations of 100 and 250 μM of PDCA decreased hydroxyproline content in roots while only the 250 μM treatment reduced the hydroxyproline content in shoots. Seedlings treated with 100 μM PDCA exhibited enhanced growth of hypocotyl and cotyledon cells and higher hydroxyproline content resulting in cotyledons with greater surface area. However, no alterations in hypocotyl length were observed. Prolyl 4 hydroxylases (P4Hs) are involved in the O-glycosylation of AGPs and were also highly expressed during seedling growth. Moreover PDCA induced a decrease in the accumulation of HRGPs and particularly in AGPs-bound epitopes in a dose dependent-manner while more drastic reduction were observed in roots compared to shoots. In addition, bulged root epidermal cells were observed at the high concentration of 250 μM which is characteristic of root tissues with glycosylation defects. These results indicate that PDCA induced pleiotropic effects during seedling growth while further studies are required to better investigate the physiological significance of this 2-oxoglutarate analog. This pharmacological approach might be used as a tool to better understand the physiological significance of HRGPs and probably P4Hs in various growth and developmental programs in plants.

Anti-fibrotic effects of Orostachys japonicus A. Berger (Crassulaceae) on hepatic stellate cells and thioacetamide-induced fibrosis in rats

BACKGROUND/OBJECTIVE

Orostachys japonicus A. Berger (Crassulaceae) has been used in traditional herbal medicines in Korea and other Asian countries to treat various diseases, including liver disorders. In the present study, the anti-fibrotic effects of O. japonicus extract (OJE) in cellular and experimental hepatofibrotic rat models were investigated.

MATERIALS/METHODS

An in vitro hepatic stellate cells (HSCs) system was used to estimate cell viability, cell cycle and apoptosis by MTT assay, flow cytometry, and Annexin V-FITC/PI staining techniques, respectively. In addition, thioacetamide (TAA)-induced liver fibrosis was established in Sprague Dawley rats. Briefly, animals were divided into five groups (n = 8): Control, TAA, OJE 10 (TAA with OJE 10 mg/kg), OJE 100 (TAA with OJE 100 mg/kg) and silymarin (TAA with Silymarin 50 mg/kg). Fibrosis was induced by treatment with TAA (200 mg/kg, i.p.) twice per week for 13 weeks, while OJE and silymarin were administered orally two times per week from week 7 to 13. The fibrotic related gene expression serum biomarkers glutathione and hydroxyproline were estimated by RT-PCR and spectrophotometry, respectively, using commercial kits.

RESULTS

OJE (0.5 and 0.1 mg/mL) and silymarin (0.05 mg/mL) treatment significantly (P < 0.01 and P < 0.001) induced apoptosis (16.95% and 27.48% for OJE and 25.87% for silymarin, respectively) in HSC-T6 cells when compared with the control group (9.09%). Further, rat primary HSCs showed changes in morphology in response to OJE 0.1 mg/mL treatment. In in vivo studies, OJE (10 and 100 mg/kg) treatment significantly ameliorated TAA-induced alterations in levels of serum biomarkers, fibrotic related gene expression, glutathione, and hydroxyproline (P < 0.05-P < 0.001) and rescued the histopathological changes.

CONCLUSIONS

OJE can be developed as a potential agent for the treatment of hepatofibrosis.

Anti-fibrotic effects of Cuscuta chinensis with in vitro hepatic stellate cells and a thioacetamide-induced experimental rat model

CONTEXT

Cuscuta chinensis Lam. (Convolvulaceae) has been used as a traditional herbal remedy for treating liver and kidney disorders.

OBJECTIVE

Anti-fibrotic effects of C. chinensis extract (CCE) in cellular and experimental animal models were investigated.

MATERIALS AND METHODS

HSC-T6 cell viability, cell cycle and apoptosis were analysed using MTT assay, flow cytometry and Annexin V-FITC/PI staining techniques. Thioacetamide (TAA)-induced fibrosis model was established using Sprague Dawley rats (n = 10). Control, TAA, CCE 10 (TAA with CCE 10 mg/kg), CCE 100 (TAA with CCE 100 mg/kg) and silymarin (TAA with silymarin 50 mg/kg). Fibrosis was induced by TAA (200 mg/kg, i.p.) twice per week for 13 weeks. CCE and silymarin were administered orally two times per week from the 7th to 13th week. Fibrotic related gene expression (α-SMA, Col1α1 and TGF-β1) was measured by RT-PCR. Serum biomarkers, glutathione (GSH) and hydroxyproline were estimated by spectrophotometer using commercial kits.

RESULTS

CCE (0.05 and 0.1 mg/mL) and silymarin (0.05 mg/mL) treatment significantly (p < 0.01 and p < 0.001) induced apoptosis (11.56%, 17.52% for CCE; 16.50% for silymarin, respectively) in activated HSC-T6 cells, compared with control group (7.26%). Further, rat primary HSCs showed changes in morphology with CCE 0.1 mg/mL treatment. In in vivo studies, CCE (10 and 100 mg/kg) treatment ameliorated the TAA-induced altered levels of serum biomarkers, fibrotic related gene expression, GSH, hydroxyproline significantly (p < 0.05-0.001) and rescued the histopathological changes.

CONCLUSIONS

CCE can be developed as a potential agent in the treatment of hepatofibrosis.

Protective effects of Ampelopsis brevipedunculata against in vitro hepatic stellate cells system and thioacetamide-induced liver fibrosis rat model

CONTEXT

Ampelopsis brevipedunculata Maxim (Vitaceae) is a traditional medicinal herb used for treating liver disorders.

OBJECTIVE

The hepatoprotective effects of A. brevipedunculata ethanol extract (ABE) was investigated in experimental models of fibrosis.

MATERIALS AND METHODS

Hepatic stellate cells (HSCs) system in vitro and thioacetamide (TAA)-induced liver fibrosis rat model in vivo were used. Sprague-Dawley rats were divided into five groups of eight each (control, TAA, TAA with ABE 10 mg/kg, ABE 100 mg/kg and silymarin 50 mg/kg groups, respectively). Fibrosis was induced except to the control group by TAA (200 mg/kg, i.p.) twice per week for 13 weeks. ABE and silymarin was administered orally six times per week from the 7th week to the 13th week.

RESULTS

In HSC-T6 cells, ABE (0.1 mg/mL) and silymarin (0.05 mg/mL) significantly (p < 0.01) induced apoptosis (12.94 ± 5.72% and 14.9 ± 3.8%, respectively) compared with control group (7.51 ± 1.26%). The expression of fibrosis related genes (TGF-β, α-SMA and Col1A1) in HSC-T6 cells were significantly (p < 0.01) downregulated in ABE-treated groups compared with control group. In in vivo studies, ABE (10 and 100 mg/kg) treatment ameliorated the altered levels of serum biomarkers significantly (p < 0.01 and p < 0.001) in TAA-induced groups. Further, ABE (10 and 100 mg/kg) significantly (p < 0.01) attenuated the altered histopathological findings, glutathione content and the accumulation of hydroxyproline.

CONCLUSION

These results collectively indicate that ABE can potentially be developed as a therapeutic agent in the treatment of hepatic fibrosis.

Identification of Collagen-Derived Hydroxyproline (Hyp)-Containing Cyclic Dipeptides with High Oral Bioavailability: Efficient Formation of Cyclo(X-Hyp) from X-Hyp-Gly-Type Tripeptides by Heating

Cyclic dipeptides (2,5-diketopiperazines) are present in a variety of foods and are reported to demonstrate antioxidant, antidepressant, and other beneficial effects. We recently developed a novel collagen hydrolysate characterized by a high content of X-hydroxyproline (Hyp)-Gly-type tripeptides using ginger protease. In the present study, we found that, through heating, X-Hyp-Gly can be easily converted into Hyp-containing cyclic dipeptides. After heating for 3 h at 85 °C and pH 4.8, Ala-Hyp-Gly was almost completely cyclized to cyclo(Ala-Hyp), in contrast to a slight cyclization of Ala-Hyp. The contents of cyclo(Ala-Hyp) and cyclo(Leu-Hyp) reached 0.5-1% (w/w) each in the ginger-degraded collagen hydrolysate under the heating conditions. Oral administration experiments using mice revealed that cyclo(Ala-Hyp) and cyclo(Leu-Hyp) were absorbed into the blood at markedly higher efficiencies compared to collagenous oligopeptides, including Pro-Hyp. The high productivity and oral bioavailability of the collagen-specific cyclic dipeptides suggest significant health benefits of the heat-treated ginger-degraded collagen hydrolysate.

Hypoglycemic, Hypolipidemic, and Wound Healing Potential of Quercetin in Streptozotocin-Induced Diabetic Rats

Background:

Among the dietary polyphenolic, quercetin is the most common compound available in vegetables and fruits. The phytochemicals are used to treat diabetic wounds and diabetes, and specifically dietary polyphenols are being extensively studied for their anti-inflammatory and antioxidant abilities.

Objective:

The objective of the study was to assess the hypoglycemic, hypolipidemic, and wound healing potential of quercetin in streptozotocin (STZ)-induced diabetic Wistar rats.

Materials and Methods:

Induction of diabetes was done by intraperitoneally administration of STZ at the dose of 55 mg/kg in Wistar rats. An excision wound was created in diabetic rats that were treated with quercetin (100 mg/kg) orally and quercetin ointment topically to evaluate the antidiabetic and wound healing potential of quercetin.

Results:

Repeated oral administration of quercetin along with topical application of quercetin ointment in diabetic rats normalized the altered blood glucose, hydroxyproline, and glucosamine levels. Topical application of quercetin ointment alone on the excised wound was sufficient enough to heal the wound area in diabetic rats.

Conclusions:

The result of the present study indicates that quercetin produces hypoglycemic effect in STZ-induced diabetic rats and normalized plasma lipids and protein profiles. Besides, this quercetin also has an excellent wound healing property when applied topically on the wound area in diabetic rats.

SUMMARY

Quercetin has hypoglycaemic and hypolipidemic potential in streptozotocin induced diabetes in wistar rats

Dermal application along with oral administrations of quercetin has more effective in wound healing in diabetic animals

Histopathological studies of pancreas, skin and liver shows significant reduction in archaeological alterations on quercetin administrations in diabetic rats.

Abbreviation used: STZ: Streptozotocin; CMC: Carboxy methyl cellulose; HDL: High density lipoproteins; LDL: low density lipoproteins.

Characterization of a Novel cis-3-Hydroxy-l-Proline Dehydratase and a trans-3-Hydroxy-l-Proline Dehydratase from Bacteria

Hydroxyprolines, such as trans-4-hydroxy-l-proline (T4LHyp), trans-3-hydroxy-l-proline (T3LHyp), and cis-3-hydroxy-l-proline (C3LHyp), are present in some proteins including collagen, plant cell wall, and several peptide antibiotics. In bacteria, genes involved in the degradation of hydroxyproline are often clustered on the genome (l-Hyp gene cluster). We recently reported that an aconitase X (AcnX)-like hypI gene from an l-Hyp gene cluster functions as a monomeric C3LHyp dehydratase (AcnX_{Type I}). However, the physiological role of C3LHyp dehydratase remained unclear. We here demonstrate that Azospirillum brasilense NBRC 102289, an aerobic nitrogen-fixing bacterium, robustly grows using not only T4LHyp and T3LHyp but also C3LHyp as the sole carbon source. The small and large subunits of the hypI gene (hypI_S and hypI_L, respectively) from A. brasilense NBRC 102289 are located separately from the l-Hyp gene cluster and encode a C3LHyp dehydratase with a novel heterodimeric structure (AcnX_{Type IIa}). A strain disrupted in the hypI_S gene did not grow on C3LHyp, suggesting its involvement in C3LHyp metabolism. Furthermore, C3LHyp induced transcription of not only the hypI genes but also the hypK gene encoding Δ¹-pyrroline-2-carboxylate reductase, which is involved in T3LHyp, d-proline, and d-lysine metabolism. On the other hand, the l-Hyp gene cluster of some other bacteria contained not only the AcnX_{Type IIa} gene but also two putative proline racemase-like genes (hypA1 and hypA2). Despite having the same active sites (a pair of Cys/Cys) as hydroxyproline 2-epimerase, which is involved in the metabolism of T4LHyp, the dominant reaction by HypA2 was clearly the dehydration of T3LHyp, a novel type of T3LHyp dehydratase that differed from the known enzyme (Cys/Thr).IMPORTANCE More than 50 years after the discovery of trans-4-hydroxy-l-proline (generally called l-hydroxyproline) degradation in aerobic bacteria, its genetic and molecular information has only recently been elucidated. l-Hydroxyproline metabolic genes are often clustered on bacterial genomes. These loci frequently contain a hypothetical gene(s), whose novel enzyme functions are related to the metabolism of trans-3-hydroxyl-proline and/or cis-3-hydroxyl-proline, a relatively rare l-hydroxyproline in nature. Several l-hydroxyproline metabolic enzymes show no sequential similarities, suggesting their emergence by convergent evolution. Furthermore, transcriptional regulation by trans-4-hydroxy-l-proline, trans-3-hydroxy-l-proline, and/or cis-3-hydroxy-l-proline significantly differs between bacteria. The results of the present study show that several l-hydroxyprolines are available for bacteria as carbon and energy sources and may contribute to the discovery of potential metabolic pathways of another hydroxyproline(s).

A Modified Hydroxyproline Assay Based on Hydrochloric Acid in Ehrlich's Solution Accurately Measures Tissue Collagen Content

Collagen quantification has long been relevant to biomedical research and clinical practice to characterize tissues and determine disease states. The hydroxyproline assay, while a broadly employed method of quantifying collagen, uses perchloric acid to dissolve Ehrlich's reagent. Since perchloric acid poses occupational safety hazards and high costs, in this study, a new hydroxyproline assay was developed that replaces perchloric acid with a relatively safer and cheaper alternative, hydrochloric acid (HCl). To validate this biochemical technique, first, using either acid to dissolve Ehrlich's reagent, the assays were completed for native and engineered collagenous tissues. No statistical differences were identified between the assays (p = 0.32). Subsequently, both biochemical techniques were compared to amino acid analysis, considered a proteomics gold standard. Interestingly, utilizing HCl in lieu of perchloric acid yielded greater concordance with amino acid analysis (ρ_c = 0.980) than did the traditional assay (ρ_c = 0.947); that is, the HCl-based assay more closely estimates hydroxyproline content, and, consequently, true collagen content. Thus, using Ehrlich's reagent containing HCl in the hydroxyproline assay represents an advance in both mitigating laboratory safety hazards and improving biochemical collagen quantification.

Toxic effect of sodium fluoride on hydroxyproline level and expression of collagen-1 gene in rat bone and its amelioration by Tamrindus indica L. fruit pulp extract

Excessive fluoride intoxication plays an important role in the development of dental, skeletal and non-skeletal fluorosis. The aim of this study was to ascertain the toxic effect of excessive fluoride ingestion on the level of hydroxyproline and expression of type 1 collagen gene in rat bone and its amelioration by supplementation with Tamarindus indica fruit pulp extract. Forty albino rats were randomly assigned to four groups. The first group served as control and received only tap water. The second group received sodium fluoride (200 ppm) through drinking water. The third group received T. indica fruit pulp extract (200 mg/kg body weight) alone and the fourth group received the T. indica fruit pulp extract (200 mg/kg body weight) along with fluorinated drinking water (200 ppm) daily by gavage for a period of 90 days. The level of hydroxyproline and expression of type 1 collagen gene using quantitative real time PCR in the tibia bone decreased significantly with continuous exposure to sodium fluoride. Co-administration of T. indica fruit pulp extract during exposure to fluoride through drinking water restored the level of calcium, phosphorus and alkaline phosphatase in serum and the concentration of hydroxyproline in urine. It increased the level of hydroxyproline and expression of type 1 collagen gene in the tibia as compared to untreated fluoride-exposed rats. It is concluded that T. indica fruit pulp extract has an ameliorative potential to protect the bone from fluoride induced collagen damage.

Cervical collagen is reduced in non-pregnant women with a history of cervical insufficiency and a short cervix

INTRODUCTION

Preterm cervical shortening and cervical insufficiency may be caused by a constitutional weakness of the cervix. The aim of this study was to assess the cervical collagen concentration in non-pregnant women with a history of cervical insufficiency or of a short cervix in the second trimester of pregnancy.

MATERIAL AND METHODS

In this case-control study we included non-pregnant women one year or more after pregnancy: 55 controls with a history of normal delivery; 27 women with a history of cervical insufficiency; and 10 women with a history of a short cervix (<5th percentile) and 10 women with a history of a long cervix (>95th percentile) at gestational weeks 18-20. We obtained biopsies (3 × 3-4 mm) from the ectocervix and determined the collagen concentration by measuring the hydroxyproline concentration.

RESULTS

Women with cervical insufficiency had lower collagen concentrations (63.5 ± 5.1%; mean ± SD) compared with controls (68.2 ± 5.4%; p = 0.0004); area under the ROC curve 0.73 (95% CI 0.62-0.84). A cut-off value at 67.6% collagen resulted in a positive likelihood ratio of 3.2, a sensitivity of 60%, and a specificity of 81%. Also, women with a short cervix in the second trimester had lower collagen concentrations in a non-pregnant state (62.1% ± 4.9%) compared with women with a long cervix (67.8% ± 5.0%; p = 0.02).

CONCLUSIONS

Both cervical insufficiency and a short cervix in the second trimester of pregnancy are associated with low cervical collagen concentrations in a non-pregnant state more than one year after pregnancy.

An evaluation of the use of pentosidine as a biomarker for ageing turtles

Concentrations of the biomarker pentosidine have been shown to be useful measures of age for a number of avian and mammalian species. However, no study has examined its usefulness as an age marker in a long-lived ectotherm despite the fact that such a marker could prove useful in understanding age distributions of populations subject to conservation programmes. Therefore, we evaluated pentosidine concentrations in the interdigital webbing of 117 female yellow mud turtles (Kinosternon flavescens) at a 35 year study site in western Nebraska where nearly all turtles are of known age. Pentosidine concentrations were extraordinarily low and positively correlated with age in this turtle, but concentrations were too variable to permit precise estimates of age for turtles of unknown age. These results may reflect the remarkable physiological adaptations of this turtle to low temperatures and oxygen deprivation in a highly seasonal environment requiring prolonged hibernation. Whether pentosidine concentrations in other ectotherms occupying less seasonal environments would be more highly correlated with age remains to be determined. However, our results suggest that patterns of accumulation of pentosidine in ectotherms may be fundamentally different from those in endotherms.

Effects of prolonged methylprednisolone treatment after pulse therapy for paraquat-intoxicated rats

OBJECTIVE

This study was designed to evaluate prolonged methylprednisolone (MP) treatment after pulse therapy for paraquat (PQ)-intoxicated rats.

METHOD

Acute PQ toxicity was induced by intraperitoneally injecting single toxic dose of 25 mg/kg of body weight. Rats were divided into four groups: control group (saline solution for 15 days), PQ group (saline solution for 15 days after PQ toxicity), pulse group (15 mg·kg^-1·day^-1 MP for 3 days after PQ toxicity and then saline solution for 12 days) and pulse + prolonged group (15 mg·kg^-1·day^-1 MP for 3 days after PQ toxicity; dosage was subsequently reduced by half every 2 days, and MP was terminated until 0.47 mg·kg^-1·day^-1). Hydroxyproline (HYP) content in lung tissues was evaluated through enzyme-linked immunosorbent assay, and lung fibrosis was examined using a semiquantitative scoring system (Ashcroft staging criteria). Lung wet-to-dry weight (W/Dc) ratio and 15-day survival rates of the rats were also analysed.

RESULTS

Similar survival rates (55.0 vs. 65.0%) were obtained for the pulse group and the pulse + prolonged group. The W/Dc (4.79 ± 0.42 vs. 5.29 ± 0.35), HYP content in the lung tissues (3.23 ± 0.24 vs. 3.72 ± 0.23 μg/mg) and lung fibrosis scores (2.69 ± 0.74 vs. 3.12 ± 0.60) of the pulse + prolonged group were lower than those of the pulse group.

CONCLUSION

Prolonged MP treatment after pulse therapy could effectively ameliorate PQ-intoxicated acute lung injury in rats. However, further studies should be performed to verify our findings.

Proline Hydroxylation in Cell Wall Proteins: Is It Yet Possible to Define Rules?

Cell wall proteins (CWPs) play critical and dynamic roles in plant cell walls by contributing to developmental processes and response to environmental cues. Since the CWPs go through the secretion pathway, most of them undergo post-translational modifications (PTMs) which can modify their biological activity. Glycosylation is one of the major PTMs of CWPs and refers to N-glycosylation, O-glycosylation and glypiation. Each of these PTMs occurs in different amino acid contexts which are not all well defined. This article deals with the hydroxylation of Pro residues which is a prerequisite for O-glycosylation of CWPs on hydroxyproline (Hyp) residues. The location of Hyp residues is well described in several structural CWPs, but yet rarely described in other CWPs. In this article, it is studied in detail in five Arabidopsis thaliana proteins using mass spectrometry data: one of them (At4g38770, AtPRP4) is a structural CWP containing 32.5% of Pro residues arranged in typical motifs, the others are either rich (27-28%, At1g31580 and At2g10940) or poor (6-8%, At1g09750 and At3g08030) in Pro residues. The known rules of Pro hydroxylation allowed a good prediction of Hyp location in AtPRP4. However, they could not be applied to the other proteins whatever their Pro content. In addition, variability of the Pro hydroxylation patterns was observed within some amino acid motifs in all the proteins and new patterns of Pro hydroxylation are described. Altogether, this work shows that Hyp residues are present in more protein families than initially described, and that Pro hydroxylation patterns could be different in each of them. This work paves the way for completing the existing Pro hydroxylation code.

[Age-related dynamics of the main extracellular matrix components in residents of the Russian Arctic]

The main extracellular matrix components in Arctic residents were studied. Northerners had increased levels of total glycosaminoglycans, hyaluronan, and collagen IV in plasma and both general and peptide-bound hydroxyproline in urine, which indicates an accelerated metabolism of the main extracellular matrix components compared with comparison group (residents of Siberia). Age-related remodeling of extracellular matrix in northerners manifested in changing ratio and quantity of its main components. Levels of total glycosaminoglycans, hyaluronan, fibronectin, hydroxyproline and its fractions increased with age while the level of collagen IV changed insignificantly. Average positive correlation between extracellular matrix components and biological aging indicators is suggestive of relationship between these two processes: aging - which is accelerated in the Arctic and pathological remodeling of extracellular matrix as it is associated with accelerated aging. Changes in local regulation system including those related to matrix metalloproteinases and their tissue inhibitors may be one of the reasons for pathological remodeling of extracellular matrix.

Ethanol extract of Cotinus coggygria leaves accelerates wound healing process in diabetic rats

CONTEXT

Cotinus coggygria Scop. (Anacardiaceae) leaves that were used as wound healing in traditional Balkan and Anatolian folk medicine, could be potentially effective in treating diabetic wounds.

OBJECTIVE

This study investigates biochemical and histological effects of ethanol extract of C. coggygria (CCE) on excision wound model in diabetic rats.

MATERIALS AND METHODS

This study was conducted on diabetic Wistar albino rats, which were injected by a single dose (50 mg/kg i.p.) streptozotocin. Afterward an excision wound model was created in all animals; diabetic control rats were applied topically simple ointment and diabetic treatment rats were applied topically 5% (w/w) ointment with CC, once a day during the experimental period. Malondialdehyde, glutathione and hydroxyproline levels in wound tissues were investigated at the end of 3rd, 7th, and 14th days. Histopathological examination was also performed.

RESULTS

Hydroxyproline content was significantly increased in the CCE treated group versus control after the 3rd and 7th days (15.33 versus 11.83; 19.67 versus 15.67 mg/g, p < 0.05; respectively). A statistically significant elevation in glutathione at the end of 3rd, 7th, and 14th days (5.13 versus 1.58, p < 0.05; 4.72 versus 1.88, p < 0.05; 3.83 versus 1.88 μmol/g, p < 0.05, respectively) and a statistically significant decrease in malondialdehyde level at the end of 7th day (4.49 versus 1.48 nmol/g, p < 0.05) were determined in the treated group versus control group. These results were also supported by histological analyses.

DISCUSSION AND CONCLUSION

These findings indicate that CCE accelerated the cutaneous wound healing process in diabetic wounds, in confirmation of its traditional use.