Decreased total carbonic anhydrase esterase activity and decreased levels of carbonic anhydrase 1 isozyme in erythrocytes of type II diabetic patients

Development of a sodium hyaluronate-enriched therapeutic formulation with stevia glycoside and mogroside V for the comprehensive management of diabetes and its complications

Diabetes prevalence continues to increase as a result of people's increasing sugar intake. Diabetes mellitus and its complications (dry skin, constipation, depression, and dental caries), as well as the prohibition of sweets ingestion, seriously affect patients' physical and mental health. Therefore, it is crucial to develop a long-term food for special medical purposes (FSMP) that aids in managing diabetes and its complications. To ensure effective biomedical function and taste, we developed a FSMP beverage formulation containing stevia glycoside, mogroside V, and sodium hyaluronate (SMH-B), each at a concentration of 0.1 mg/mL. Meanwhile, this study verified that SMH-B is an environmentally friendly and biocompatible formulation. Furthermore, both in vivo and in vitro studies have demonstrated that SMH-B significantly lowers blood glucose and lipid levels, enhances skin moisture and elasticity, prevents dental caries, alleviates constipation, reduces oxidative stress, and mitigates depressive symptoms. Notably, the SMH-B compound formula exhibits a more effective adjuvant therapeutic effect compared to single-ingredient formulation composed of stevia glycosides, mogroside V, and sodium hyaluronate. Moreover, SMH-B provides the sweetness desired by diabetic patients without affecting blood glucose levels, while also offering an auxiliary therapeutic role, making it a potential FSMP for diabetes management.

Spontaneous regression of tumours. Possible cross reactivity of autoantibodies against carbonic anhydrase I

Spontaneous tumour regression in patients after high dose therapy and autologous stem cell transplantation or patients with standard therapy is accompanied with the presence of high titers autoantibodies against carbonic anhydrase I (CA I). The concomitant presence of aplastic anaemia-like syndrome in these patients points to parallel bone marrow suppression during this period. It seems that CA I, an 'obscure' enzyme, does not have any significant physiological role in humans. One possible explanation points to the fact that autoantibodies against CA I may target another antigen(s) which is(are) important in tumour growth as well as in normal haematopoiesis. One of the candidates for such a target is the DNA polymerase theta.

New Histamine-Related Five-Membered N-Heterocycle Derivatives as Carbonic Anhydrase I Activators

A series of histamine (HST)-related compounds were synthesized and tested for their activating properties on five physiologically relevant human Carbonic Anhydrase (hCA) isoforms (I, II, Va, VII and XIII). The imidazole ring of HST was replaced with different 5-membered heterocycles and the length of the aliphatic chain was varied. For the most interesting compounds some modifications on the terminal amino group were also performed. The most sensitive isoform to activation was hCA I (K_A values in the low micromolar range), but surprisingly none of the new compounds displayed activity on hCA II. Some derivatives (1, 3a and 22) displayed an interesting selectivity for activating hCA I over hCA II, Va, VII and XIII.

Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis

In mosaic marine habitats, such as intertidal zones, ocean acidification (OA) is exacerbated by high variability of pH, temperature, and biological CO2 production. The nonlinear interactions among these drivers can be context-specific and their effect on organisms in these habitats remains largely unknown, warranting further investigation.We were particularly interested in Mytilus edulis (the blue mussel) from intertidal zones of the Gulf of Maine (GOM), USA, for this study. GOM is a hot spot of global climate change (average sea surface temperature (SST) increasing by >0.2°C/year) with >60% decline in mussel population over the past 40 years.Here, we utilize bioenergetic underpinnings to identify limits of stress tolerance in M. edulis from GOM exposed to warming and OA. We have measured whole-organism oxygen consumption rates and metabolic biomarkers in mussels exposed to control and elevated temperatures (10 vs. 15°C, respectively) and current and moderately elevated P CO2 levels (~400 vs. 800 µatm, respectively).Our study demonstrates that adult M. edulis from GOM are metabolically resilient to the moderate OA scenario but responsive to warming as seen in changes in metabolic rate, energy reserves (total lipids), metabolite profiles (glucose and osmolyte dimethyl amine), and enzyme activities (carbonic anhydrase and calcium ATPase).Our results are in agreement with recent literature that OA scenarios for the next 100-300 years do not affect this species, possibly as a consequence of maintaining its in vivo acid-base balance.

Unannotated single nucleotide polymorphisms in the TATA box of erythropoiesis genes show in vitro positive involvements in cognitive and mental disorders

BACKGROUND

Hemoglobin is a tetramer consisting of two α-chains and two β-chains of globin. Hereditary aberrations in the synthesis of one of the globin chains are at the root of thalassemia, one of the most prevalent monogenic diseases worldwide. In humans, in addition to α- and β-globins, embryonic zeta-globin and fetal γ-globin are expressed. Immediately after birth, the expression of fetal Aγ- and Gγ-globin ceases, and then adult β-globin is mostly expressed. It has been shown that in addition to erythroid cells, hemoglobin is widely expressed in nonerythroid cells including neurons of the cortex, hippocampus, and cerebellum in rodents; embryonic and adult brain neurons in mice; and mesencephalic dopaminergic brain cells in humans, mice, and rats. Lately, there is growing evidence that different forms of anemia (changes in the number and quality of blood cells) may be involved in (or may accompany) the pathogenesis of various cognitive and mental disorders, such as Alzheimer's and Parkinson's diseases, depression of various severity levels, bipolar disorders, and schizophrenia. Higher hemoglobin concentrations in the blood may lead to hyperviscosity, hypovolemia, and lung diseases, which may cause brain hypoxia and anomalies of brain function, which may also result in cognitive deficits.

METHODS

In this study, a search for unannotated single-nucleotide polymorphisms (SNPs) of erythroid genes was initially performed using our previously created and published SNP-TATA_Z-tester, which is a Web service for computational analysis of a given SNP for in silico estimation of its influence on the affinity of TATA-binding protein (TBP) for TATA and TATA-like sequences. The obtained predictions were finally verified in vitro by an electrophoretic mobility shift assay (EMSA).

RESULTS

On the basis of these experimental in vitro results and literature data, we studied TATA box SNPs influencing both human erythropoiesis and cognitive abilities. For instance, TBP-TATA affinity in the HbZ promoter decreases 6.6-fold as a result of a substitution in the TATA box (rs113180943), thereby possibly disrupting stage-dependent events of "switching" of hemoglobin genes and thus causing erythroblastosis. Therefore, rs113180943 may be a candidate marker of severe hemoglobinopathies with comorbid cognitive and mental disorders associated with cerebral blood flow disturbances.

CONCLUSIONS

The literature data and experimental and computations results suggest that the uncovered candidate SNP markers of erythropoiesis anomalies may also be studied in cohorts of patients with cognitive and/or mental disorders with comorbid erythropoiesis diseases in comparison to conventionally healthy volunteers. Research into the regulatory mechanisms by which the identified SNP markers contribute to the development of hemoglobinopathies and of the associated cognitive deficits will allow physicians not only to take timely and adequate measures against hemoglobinopathies but also to implement strategies preventing cognitive and mental disorders.

Synthesis, characterization, inhibition effects, and molecular docking studies as acetylcholinesterase, α-glycosidase, and carbonic anhydrase inhibitors of novel benzenesulfonamides incorporating 1,3,5-triazine structural motifs

Some metabolic enzyme inhibitors can be used in the treatment of many diseases. Therefore, synthesis and determination of alternative inhibitors are essential. In this study, the inhibition effect of newly synthesized compounds on carbonic anhydrase (cytosolic isoforms, hCA I and hCA II), α-glycosidase (α-GLY), and acetylcholinesterase (AChE) were investigated. The possible binding mechanism of the compounds with a high inhibitory effect on the active site of the enzyme was demonstrated by molecular docking method. We investigated the inhibition effects of novel synthesized compounds (MZ1-MZ11) on metabolic enzymes such as α-GLY, AChE, and hCA I and II. The compound MZ6 for AChE, MZ8 for CA I and CA II and MZ7 for α-GLY showed a very active inhibition profile (KIs 51.67 ± 4.76 for hCA I, 40.35 ± 5.74 nM for hCA II, 41.74 ± 8.08 nM for α-GLY and 335.76 ± 46.91 nM for AChE). The novel synthesized compounds (MZ1-MZ11) have a higher enzyme (α-GLY, AChE, hCA I, and II) inhibitory potential than ACR, TAC, and AZA, respectively. The compounds may have the potential to be used as alternative medicines after further research in the treatment of many diseases such as diabetes, Alzheimer's disease, heart failure, ulcer, and epilepsy.

Effects of seawater salinity and pH on cellular metabolism and enzyme activities in biomineralizing tissues of marine bivalves

Molluscan shell formation is a complex energy demanding process sensitive to the shifts in seawater CaCO₃ saturation due to changes in salinity and pH. We studied the effects of salinity and pH on energy demand and enzyme activities of biomineralizing cells of the Pacific oyster (Crassostrea gigas) and the hard-shell clam (Mercenaria mercenaria). Adult animals were exposed for 14 days to high (30), intermediate (18), or low (10) salinity at either high (8.0-8.2) or low (7.8) pH. Basal metabolic cost as well as the energy cost of the biomineralization-related cellular processes were determined in isolated mantle edge cells and hemocytes. The total metabolic rates were similar in the hemocytes of the two studied species, but considerably higher in the mantle cells of C. gigas compared with those of M. mercenaria. Cellular respiration was unaffected by salinity in the clams' cells, while in oysters' cells the highest respiration rate was observed at intermediate salinity (18). In both studied species, low pH suppressed cellular respiration. Low pH led to an upregulation of Na⁺/K⁺ ATPase activity in biomineralizing cells of oysters and clams. Activities of Ca²⁺ ATPase and H⁺ ATPase, as well as the cellular energy costs of Ca²⁺ and H⁺ transport in the biomineralizing cells were insensitive to the variation in salinity and pH in the two studied species. Variability in cellular response to low salinity and pH indicates that the disturbance of shell formation under these conditions has different underlying mechanisms in the two studied species.

Transgenerational biochemical effects of seawater acidification on the Manila clam (Ruditapes philippinarum)

Ocean acidification can negatively impact marine bivalves. Pivotal to projecting their fate is the ability to acclimate and adapt to shifts in seawater chemistry. Transgenerational plasticity enables marine bivalves to acclimate, yet the underlying mechanisms at different levels of biological organization remain poorly understood. Here, we performed a transgenerational experiment to understand biochemical responses of the Manila clam, Ruditapes philippinarum, following exposure to moderately reduced seawater pH (from 8.1 to 7.7). Activities of tissue calcification-relevant enzymes, such as carbonic anhydrase (CA), acid phosphatase (ACP) and alkaline phosphatase (ALP), energy-metabolizing enzymes, such as Na⁺/K⁺-ATPase (NKA) and Ca²⁺/Mg²⁺-ATPase (CMA), as well as tissue energy reserves (glycogen, lipid and protein) were assayed. With decreasing seawater pH, adult R. philippinarum exhibited significantly increased CA activity, and especially the clams with a history of transgenerational exposure displaying significantly higher CA activity than those spawned from parents exposed to ambient seawater pH. Yet, ACP and ALP activities remained unaffected. Transgenerational exposure to reduced seawater pH led to significant increases of NKA activity, while no transgenerational response of CMA activity was observed. Tissue glycogen and lipid contents were significantly depleted under acidified conditions regardless of transgenerational exposure. Yet, transgenerational alleviation in the net protein degradation was found. These findings suggest that our current understanding of transgenerational responses is still limited by the achievable time-window possible in the laboratory. While the energetic budget is lower under acidified conditions, there is no evidence of transgenerational recovery in term of energetic budget. Therefore, this work demonstrates that the critical basis of ocean acidification resilience can most likely be explained in energetic terms.

Hepatic transcriptome and proteome analyses provide new insights into the regulator mechanism of dietary avicularin in diabetic mice

Many dietary flavonoids existing as glycosides in fruits and vegetables are considered bioactive food components with various potential health benefits. Type 2 diabetes mellitus (T2DM) is a complex and polygenic disease with increasing global prevalence and economic burden. In this study, the hypoglycemic effect of avicularin (quercetin-3-O-α-arabinofuranoside), a flavonoid glycoside commonly found in natural plants and fruits, was determined in a high fat diet/streptozotocin induced type 2 diabetes mouse model. Our results demonstrated that dietary avicularin treatment reduced levels of fasting blood glucose, serum TG and LDL-C, liver AST and ALT, and increased hepatic glycogen in T2DM mice. Furthermore, we used RNA-Seq and iTRAQ to compare the gene and protein expression in the livers of the normal control mice (NC), diabetic control mice (DC) and avicularin treated mice (DA100). The differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were analyzed based on gene annotations and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Integrated analysis of the RNA-Seq and iTRAQ data indicated that the fifteen DEGs/DEPs showed the same trend in mRNA and protein expression levels in comparisons of both NC vs DC and DC vs DA100. KEGG analysis revealed that four DEGs/DEPs (PKM, PEPCK, PYG, and PLA2) in the glycolysis, gluconeogenesis, and arachidonic acid pathway, and six DEPs (Ndufb4, Ndufa6, Cox5a, Cox5b, Cox6c, and ATPSβ) in the oxidative phosphorylation signaling pathway, play important roles in avicularin's hypoglycemic effect. We also found six other DEGs/DEPs related to T2DM (CA1, Serpinb6a, AK, Pcolce, Cand2, and Atp2a3), and five related to cancer (Phgdh, Tes, Papss1, Psat1, and Fam49b). We did further verify by qRT-PCR and explored the possible binding modes of avicularin with targeted proteins with molecular docking simulations. Taken together, our results demonstrated the protective effects of avicularin against diabetes and provided a global view about the system-level hypoglycemic mechanisms of avicularin by the comprehensive analysis of transcriptomic and proteomic data in T2DM mice.

Silencing of carbonic anhydrase I enhances the malignant potential of exosomes secreted by prostatic tumour cells

We report results showing that the silencing of carbonic anhydrase I (siCA1) in prostatic (PC3) tumour cells has a significant impact on exosome formation. An increased diameter, concentration and diversity of the produced exosomes were noticed as a consequence of this knock‐down. The protein composition of the exosomes' cargo was also altered. Liquid chromatography and mass spectrometry analyses identified 42 proteins significantly altered in PC3 siCA1 exosomes compared with controls. The affected proteins are mainly involved in metabolic processes, biogenesis, cell component organization and defense/immunity. Interestingly, almost all of them have been described as ‘enhancers' of tumour development through the promotion of cell proliferation, migration and invasion. Thus, our results indicate that the reduced expression of the CA1 protein enhances the malignant potential of PC3 cells.

Results, meta-analysis and a first evaluation of UNOxR, the urinary nitrate-to-nitrite molar ratio, as a measure of nitrite reabsorption in experimental and clinical settings

We recently found that renal carbonic anhydrase (CA) is involved in the reabsorption of inorganic nitrite (NO₂^-), an abundant reservoir of nitric oxide (NO) in tissues and cells. Impaired NO synthesis in the endothelium and decreased NO bioavailability in the circulation are considered major contributors to the development and progression of renal and cardiovascular diseases in different conditions including diabetes. Isolated human and bovine erythrocytic CAII and CAIV can convert nitrite to nitrous acid (HONO) and its anhydride N₂O₃ which, in the presence of thiols (RSH), are further converted to S-nitrosothiols (RSNO) and NO. Thus, CA may be responsible both for the homeostasis of nitrite and for its bioactivation to RSNO/NO. We hypothesized that enhanced excretion of nitrite in the urine may contribute to NO-related dysfunctions in the renal and cardiovascular systems, and proposed the urinary nitrate-to-nitrite molar ratio, i.e., U_NOxR, as a measure of renal CA-dependent excretion of nitrite. Based on results from clinical and experimental animal studies, here, we report on a first evaluation of U_NOxR. We determined U_NOxR values in preterm neonates, healthy children, and adults, in children suffering from type 1 diabetes mellitus (T1DM) or Duchenne muscular dystrophy (DMD), in elderly subjects suffering from chronic rheumatic diseases, type 2 diabetes mellitus (T2DM), coronary artery disease (CAD), or peripheral arterial occlusive disease (PAOD). We also determined U_NOxR values in healthy young men who ingested isosorbide dinitrate (ISDN), pentaerythrityl tetranitrate (PETN), or inorganic nitrate. In addition, we tested the utility of U_NOxR in two animal models, i.e., the LEW.1AR1-iddm rat, an animal model of human T1DM, and the APOE*3-Leiden.CETP mice, a model of human dyslipidemia. Mean U_NOxR values were lower in adult patients with rheumatic diseases (187) and in T2DM patients of the DALI study (74) as compared to healthy elderly adults (660) and healthy young men (1500). The intra- and inter-variabilities of U_NOxR were of the order of 50% in young and elderly healthy subjects. U_NOxR values were lower in black compared to white boys (314 vs. 483, P = 0.007), which is in line with reported lower NO bioavailability in black ethnicity. Mean U_NOxR values were lower in DMD (424) compared to healthy (730) children, but they were higher in T1DM children (1192). ISDN (3 × 30 mg) decreased stronger U_NOxR compared to PETN (3 × 80 mg) after 1 day (P = 0.046) and after 5 days (P = 0.0016) of oral administration of therapeutically equivalent doses. In healthy young men who ingested NaNO₃ (0.1 mmol/kg/d), U_NOxR was higher than in those who ingested the same dose of NaCl (1709 vs. 369). In LEW.1AR1-iddm rats, mean U_NOxR values were lower than in healthy rats (198 vs. 308) and comparable to those in APOE*3-Leiden.CETP mice (151).

New Strategy for in Vitro Determination of Carbonic Anhydrase Activity from Analysis of Oxygen-18 Isotopes of CO2

The oxygen-18 isotopic (¹⁸O) composition in CO₂ provides an important insight into the variation of rate in isotopic fractionation reaction regulated by carbonic anydrase (CA) metalloenzyme. This work aims to employ an ¹⁸O-isotope ratio-based analytical method for quantitative estimation of CA activity in erythrocytes for clinical testing purposes. Here, a new method has been developed that contains the measurements of ¹⁸O/¹⁶O isotope ratios during oxygen-18 isotopic exchange between ¹²C¹⁶O¹⁶O and H₂¹⁸O of an in vitro biochemical reaction controlled by erythrocytes CA and estimation of enzymatic activity of CA from the isotopic composition of CO₂. We studied the enrichments of ¹⁸O-isotope of CO₂ with increments of CA activities during isotopic fractionation reaction. To check the influence of subject-specific body temperature, pH, H₂¹⁸O, and cellular produced CO₂ on this reaction, we performed the in vitro experiments in closed containers with variations of those parameters. Finally, we mimicked the exchange reaction at 5% [CO₂], 5‰ [H₂¹⁸O], pH of 7.4, and temperature of 37 °C to create the physiological environment equivalent to that of the human body and monitored the exchange kinetics with variations of CA activities, and subsequently, we derived the quantitative relation between the ¹⁸O-isotope of CO₂ and CA activity in erythrocytes. This assay may be applicable for rapid and simple quantification of carbonic anhydrase activity which is very important to prevent the carbonic-anhydrase-associated disorders in human.

Silencing of CA1 mRNA in tumour cells does not change the gene expression of the extracellular matrix proteins

We report the silencing of CA1 mRNA in PC3 and MDA cells. The levels of mRNA coding CA1 protein in the knock-down mRNA (CA1 siRNA) cells have been measured by RT-PCR and were approximately 5% (PC3) and 20% (MDA-MB-231), respectively, of the level of control (Mock siRNA) used during silencing. In PC3 and MDA-MB-231 cells, the mRNAs for COL1A1 and COL4A4 were up-regulated. The mRNAs for CTHRC1, LAMC2, and WNT7B were not changed when compared to the control. The morphology of the cells during the treatments remained the same. On the Western blots, the lysate from the silenced cells showed lower levels of CA I as well.

Sera of patients with spontaneous tumour regression and elevated anti-CA I autoantibodies change the gene expression of ECM proteins

Spontaneous tumour regression after high‐dose therapy and autologous stem cell transplantation is associated with the aplastic anaemia‐like syndrome and the presence of polyclonal autoantibodies against carbonic anhydrase I (CA I). When tumour cells were grown in vitro in the presence of patients’ sera positive for anti‐CA I autoantibodies, their morphological pattern was altered. These changes were accompanied by modifications in the gene expression profile. We observed downregulation of genes of the basal lamina assembly (collagen type IV alpha 4, the laminin subunit gamma 2), the extracellular matrix (collagen type I alpha 1), the cytoskeleton (keratin 14 type I), the collagen triple helix repeat containing 1 and the proto‐oncogene WNT7B. On the other hand, the expression of the CA 1 gene was increased in the tumour cells. It was also noticed that the presence of anti‐CA I autoantibodies did not impair tumour cell proliferation and cell viability in vitro. These findings were observed only in the presence of patients’ sera positive for anti‐CA I autoantibodies.

The effect of erythrocyte membranes from diabetic and hypercholesterolemic individuals on human carbonic anhydrase II activity

CONTEXT

Erythrocyte membranes regulate many enzyme activities, including carbonic anhydrase II (CA II). Membrane fluidity is associated with alterations in protein function and protein-protein interactions.

OBJECTIVE

The purpose of this study was to show the human CA II (hCA II) activity regulation by human erythrocyte membranes from diabetic and hypercholesterolemic subjects.

MATERIALS AND METHODS

Erythrocyte membranes were obtained from diabetic, hypercholesterolemic, and healthy subjects. hCA II activity was measured using the electrometric method.

RESULTS

hCA II activity was increased in vitro by membranes from both diabetic and hypercholesterolemic patients, with hypercholesterolemic membranes exhibiting a greater increase.

CONCLUSION

Changes in membrane composition may affect the erythrocyte membranes' capacity to increase in vitro hCA II activity.

Oxygen-18 isotope of breath CO₂ linking to erythrocytes carbonic anhydrase activity: a biomarker for pre-diabetes and type 2 diabetes

Carbonic anhydrase (CA), a well-characterized metalloenzyme, is associated with oxygen-18 ( ¹⁸O)-isotopic fractionations of CO₂. To investigate how CA activity links the ¹⁸O of breath CO₂ to pre-diabetes (PD) and type 2 diabetes (T2D) during metabolism, we studied pre- and post-dose CA activities in erythrocytes with simultaneous monitoring of ¹⁸O/ ¹⁶O-isotope ratios of breath CO₂ and thereafter elucidated potential metabolic pathways underlying CA alteration in the pathogenesis of T2D. Here we show that the post-dose CA activity in both T2D and PD was markedly enhanced, whereas the non-diabetic controls (NDC) exhibited a considerable reduction in post-dose CA activity when compared with their basal CA activities. However, T2D and PD exhibited isotopic enrichments of ¹⁸O in breath CO₂, while a marked depletion of ¹⁸O in CO₂ was manifested in NDC. Thus, the isotopic enrichments and depletions of ¹⁸O in breath CO₂ were well correlated with the changes in CA activities for controls, PD and T2D. Our findings suggest the changes in CA activities in erythrocytes may contribute to the pathogenesis of T2D and the breath C ¹⁸O ¹⁶O regulated by the CA activity as a potential biomarker for non-invasive assessment of T2D, and thus may open a new method for treating T2D.

Renal carbonic anhydrases are involved in the reabsorption of endogenous nitrite

Nitrite (ONO(-)) exerts nitric oxide (NO)-related biological actions and its concentration in the circulation may be of particular importance. Nitrite is excreted in the urine. Hence, the kidney may play an important role in nitrite/NO homeostasis in the vasculature. We investigated a possible involvement of renal carbonic anhydrases (CAs) in endogenous nitrite reabsorption in the proximal tubule. The potent CA inhibitor acetazolamide was administered orally to six healthy volunteers (5 mg/kg) and nitrite was measured in spot urine samples before and after administration. Acetazolamide increased abruptly nitrite excretion in the urine, strongly suggesting that renal CAs are involved in nitrite reabsorption in healthy humans. Additional in vitro experiments support our hypothesis that nitrite reacts with CO(2), analogous to the reaction of peroxynitrite (ONOO(-)) with CO(2), to form acid-labile nitrito carbonate [ONOC(O)O(-)]. We assume that this reaction is catalyzed by CAs and that nitrito carbonate represents the nitrite form that is actively transported into the kidney. The significance of nitrite reabsorption in the kidney and the underlying mechanisms, notably a direct involvement of CAs in the reaction between nitrite and CO(2), remain to be elucidated.

Interactive effects of salinity and elevated CO2 levels on juvenile eastern oysters, Crassostrea virginica

Rising levels of atmospheric CO2 lead to acidification of the ocean and alter seawater carbonate chemistry, which can negatively impact calcifying organisms, including mollusks. In estuaries, exposure to elevated CO2 levels often co-occurs with other stressors, such as reduced salinity, which enhances the acidification trend, affects ion and acid–base regulation of estuarine calcifiers and modifies their response to ocean acidification. We studied the interactive effects of salinity and partial pressure of CO2 (PCO2) on biomineralization and energy homeostasis in juveniles of the eastern oyster, Crassostrea virginica, a common estuarine bivalve. Juveniles were exposed for 11 weeks to one of two environmentally relevant salinities (30 or 15 PSU) either at current atmospheric PCO2 (∼400 μatm, normocapnia) or PCO2 projected by moderate IPCC scenarios for the year 2100 (∼700–800 μatm, hypercapnia). Exposure of the juvenile oysters to elevated PCO2 and/or low salinity led to a significant increase in mortality, reduction of tissue energy stores (glycogen and lipid) and negative soft tissue growth, indicating energy deficiency. Interestingly, tissue ATP levels were not affected by exposure to changing salinity and PCO2, suggesting that juvenile oysters maintain their cellular energy status at the expense of lipid and glycogen stores. At the same time, no compensatory upregulation of carbonic anhydrase activity was found under the conditions of low salinity and high PCO2. Metabolic profiling using magnetic resonance spectroscopy revealed altered metabolite status following low salinity exposure; specifically, acetate levels were lower in hypercapnic than in normocapnic individuals at low salinity. Combined exposure to hypercapnia and low salinity negatively affected mechanical properties of shells of the juveniles, resulting in reduced hardness and fracture resistance. Thus, our data suggest that the combined effects of elevated PCO2 and fluctuating salinity may jeopardize the survival of eastern oysters because of weakening of their shells and increased energy consumption.

Proteomic identification of salivary biomarkers of type-2 diabetes

The identification of biomarkers to noninvasively detect prediabetes/diabetes will facilitate interventions designed to prevent or delay progression to frank diabetes and its attendant complications. The purpose of this study was to characterize the human salivary proteome in type-2 diabetes to identify potential biomarkers of diabetes. Whole saliva from control and type-2 diabetic individuals was characterized by multidimensional liquid chromatography/tandem mass spectrometry (2D-LC-MS/MS). Label-free quantification was used to identify differentially abundant protein biomarkers. Selected potential biomarkers were then independently validated in saliva from control, diabetic, and prediabetic subjects by Western immunoblotting and ELISA. Characterization of the salivary proteome identified a total of 487 unique proteins. Approximately 33% of these have not been previously reported in human saliva. Of these, 65 demonstrated a greater than 2-fold difference in abundance between control and type-2 diabetes samples. A majority of the differentially abundant proteins belong to pathways regulating metabolism and immune response. Independent validation of a subset of potential biomarkers utilizing immunodetection confirmed their differential expression in type-2 diabetes, and analysis of prediabetic samples demonstrated a trend of relative increase in their abundance with progression from the prediabetic to the diabetic state. This comprehensive proteomic analysis of the human salivary proteome in type-2 diabetes provides the first global view of potential mechanisms perturbed in diabetic saliva and their utility in detection and monitoring of diabetes. Further characterization of these markers in a larger cohort of subjects may provide the basis for new, noninvasive tests for diabetes screening, detection, and monitoring.

Investigations of the esterase, phosphatase, and sulfatase activities of the cytosolic mammalian carbonic anhydrase isoforms I, II, and XIII with 4-nitrophenyl esters as substrates

The esterase, phosphatase, and sulfatase activities of carbonic anhydrase (CA, EC 4.2.1.1) isozymes, CA I, II, and XIII with 4-nitrophenyl esters as substrates was investigated. These enzymes show esterase activity with 4-nitrophenyl acetate as substrate, with second order rate constants in the range of 753-7706M(-1)s(-1), being less effective as phosphatases (k(cat)/K(M) in the range of 14.89-1374.40M(-1)s(-1)) and totally ineffective sulfatases. The esterase/phosphatase activities were inhibited by sulfonamide CA inhibitors, proving that the zinc-hydroxide mechanism responsible for the CO(2) hydrase activities of CAs is also responsible for their esterase/phosphatase activity. CA XIII was the most effective esterase and phosphatase. CA XIII might catalyze other physiological reactions than CO(2) hydration, based on its relevant phosphatase activity.