Microbial induced calcium carbonate precipitation (MICP) refers to the natural biological process of calcium carbonate precipitation induced by microbial metabolism in its surrounding environment. Based on the principles of MICP, microbial cement has been developed and has received widespread attention in the field of biology, civil engineering, and environment owing to the merits of environmental friendliness and economic competence. Urease and carbonic anhydrase are the key enzymes closely related to microbial cement. This review summarizes the genes, protein structures, regulatory mechanisms, engineering strains and mutual synergistic relationship of these two enzymes. The application of bioinformatics and synthetic biology is expected to develop biocement with a wide range of environmental adaptability and high performance, and will bring the MICP research to a new height.
Calcium Carbonate/metabolism* ; Chemical Precipitation ; Urease/metabolism*

Bile ; analysis ; Calcium Carbonate ; metabolism ; Gallbladder Diseases ; diagnosis ; metabolism ; Humans ; Hydrogen-Ion Concentration ; Male ; Middle Aged

OBJECTIVE: To investigate the effect of RUNX2 gene overexpression vector modified exosomes derived from bone marrow mesenchymal stem cells (BMSCs) combined with calcium carbonate scaffold system in bone defect. METHODS: Rabbit BMSCs were used as the research object, and BMSCs were identified by flow cytometry. Construct RUNX2 gene overexpression vector, transfect BMSCs with lentivirus, and collect exosomes by ultracentrifugation. The morphology of exosomes was observed by transmission electron microscope, the expression of exosome marker CD63 was detected by Western blot, and the calcium carbonate scaffold was constructed by three chamber parallel automatic temperature control reaction system. According to whether the RUNX2 gene overexpression vector was transfected or not, the complex of BMSCs and calcium carbonate scaffold was divided into three groups, namely BMSCs group, RUNX2 overexpression group and exosome group. The osteogenic differentiation of BMSCs was detected by oil red O staining and RT-PCR. There were 9 clean adult healthy male New Zealand white rabbits, aged (12.97±1.21) months, with a body weight of (19.3±3.6) kg, with 3 rabbits in each group. The animal model of skull defect was constructed by surgical method, and the repair of bone defect was evaluated by imaging, he staining and Masson staining. RESULTS: The results of flow cytometry showed that the expression of CD29 protein, CD44 protein, CD11b protein and CD45 protein on the surface of BMSCs were 99.5%, 100%, 0.1% and 0.1%, respectively. Transmission electron microscopy showed that the exosomes were bilayer vesicles with a diameter of 50 to 150 nm. Western blot showed that the molecular marker CD63 of exosomes was positive. Oil red O staining showed that the osteogenic differentiation of BMSCs in exosome group was significantly higher than that in RUNX2 overexpression group and BMSCs group. The results of RT-PCR showed that the relative expressions of RUNX2, BMP-2 and ALP mRNA in BMSCs in exosome group were significantly higher than those in RUNX2 overexpression group and BMSCs group (P<0.05). The imaging results showed that the repair effect of skull defect in exosome group was better than that in RUNX2 overexpression group. HE staining and Masson staining showed that the repair effect of skull defect in exosome group was better than that in RUNX2 overexpression group (P<0.05). MSCs in exosome group was significantly higher than that in RUNX2 overexpression group and BMSCs group. The results of RT-PCR showed that the relative expressions of RUNX2, BMP-2 and ALP mRNA in BMSCs in exosome group were significantly higher than those in RUNX2 overexpression group and BMSCs group(P<0.05). The imaging results showed that the repair effect of skull defect in exosome group was better than that in RUNX2 overexpression group. HE staining and Masson staining showed that the repair effect of skull defect in exosome group was better than that in RUNX2 overexpression group(P<0.05). CONCLUSION Compared with RUNX2 gene overexpression vector transfection, extraction of exosomes directly can promote the differentiation of BMSCs into osteoblasts more efficiently, and the combination with calcium carbonate scaffold can better promote the healing of bone defects. So as to provide new ideas and methods for the clinical treatment of bone defects.
Animals ; Calcium Carbonate/metabolism* ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Exosomes/metabolism* ; Humans ; Male ; Osteogenesis/genetics* ; RNA, Messenger/metabolism* ; Rabbits

Idiopathic hypoparathyroidism is a relatively rare disease characterized by hypocalcemia and hyperphosphatemia: this is due to a deficiency or a sereretory disorder of the parathyroid hormone without any prior operation nor underlying medical disoder. Calcium carbonate and vitamin D substitution are generally considered as the mainstay of therapy, but these treatments can cause hypercalcemia and hypercalciuria. Persistent ingestion of large amount of calcium carbonate can cause milk-alkali syndrome that is characterized by hypercalcemia, metabolic alkalosis and renal failure. Once a patient is diagnosed with milk-alkali syndrome, withdrawal of calcium carbonate and vitamin D is essential and treatment with saline diuresis and furosemide is the usually effective. In treatmenf of hypoparathyroidism with calcium carbonate and vitamin D substitution, evaluation of serum calcium and urinary calcium excretion is essential to avoid hypercalcemia and ypercalciuria. We concluded that during treatment with calcium carbonate and vitamin D substitution for patients with idiopathic hypoparathyroidism, they should have carefully laboratory monitoring, and they should be made aware of the circumstances influencing calcium metabolism
Alkalosis ; Calcium ; Calcium Carbonate ; Diuresis ; Eating ; Furosemide ; Humans ; Hypercalcemia* ; Hypercalciuria ; Hyperphosphatemia ; Hypocalcemia ; Hypoparathyroidism* ; Metabolism ; Parathyroid Hormone ; Rare Diseases ; Renal Insufficiency ; Vitamin D

Idiopathic hypoparathyroidism is a relatively rare disease characterized by hypocalcemia and hyperphosphatemia: this is due to a deficiency or a sereretory disorder of the parathyroid hormone without any prior operation nor underlying medical disoder. Calcium carbonate and vitamin D substitution are generally considered as the mainstay of therapy, but these treatments can cause hypercalcemia and hypercalciuria. Persistent ingestion of large amount of calcium carbonate can cause milk-alkali syndrome that is characterized by hypercalcemia, metabolic alkalosis and renal failure. Once a patient is diagnosed with milk-alkali syndrome, withdrawal of calcium carbonate and vitamin D is essential and treatment with saline diuresis and furosemide is the usually effective. In treatmenf of hypoparathyroidism with calcium carbonate and vitamin D substitution, evaluation of serum calcium and urinary calcium excretion is essential to avoid hypercalcemia and ypercalciuria. We concluded that during treatment with calcium carbonate and vitamin D substitution for patients with idiopathic hypoparathyroidism, they should have carefully laboratory monitoring, and they should be made aware of the circumstances influencing calcium metabolism
Alkalosis ; Calcium ; Calcium Carbonate ; Diuresis ; Eating ; Furosemide ; Humans ; Hypercalcemia* ; Hypercalciuria ; Hyperphosphatemia ; Hypocalcemia ; Hypoparathyroidism* ; Metabolism ; Parathyroid Hormone ; Rare Diseases ; Renal Insufficiency ; Vitamin D

Oral phosphate binders and high calcium dialysate have been used as standard therapies for dialysis patients to prevent renal osteodystrophy. Calcium containing phosphate binders are used to prevent intestinal absorption of dietary phosphate and to avoid aluminum loading by using aluminum containing phosphate binders. The use of calcium products resulted in hypercalcemia in a substantial portion of dialysis population. Calcium carbonate as a phophate binder is widely used in Korea. However, the incidence of hypercalcemia in Korean dialysis patients has not been reported to date. In this study we evaluated the incidence of hypercalcemia in dialysis patients. Patients with associated diseases that may influence serum calcium level were excluded from the study. A total of 180dialysis patients (116 HD patients and 64 CAPD patients) maintained at Soon Chun Hyang University Hospital were included. Three consecutive 2 monthly measurements of serum calcium, phosphate, albumin, alkaline phosphatase, bicarbonate in HD and two consecutive measurements in 3 month interval in CAPD patients were retrospectively evaluated. Ionized calcium and intact parathyroid hormone (N-terminal) were measured every 6 months. Serum total calcium level was corrected by serum albumin level. Three HD patients(2.5%) were hypercalcemic pre-HD while 50(43.1%) hypercalcemic postdialysis. 5 CAPD patients(7.8%) were hypercalcemic. Pre-HD calcium level did not differ from the value in CAPD patients. An average value of pre-and post-HD calcium, and serum albumin levels were significantly higher in HD patients than those values in CAPD patients(p<0.01). Ionized calcium (p<0.01) and serum PTH(p<0.05) levels were significantly higher, while serum bicarbonate level (p<0.01) was significantly lower in HD patients than in CAPD patients. The amount of calcium carbonate used were 2.2g in HD and 2.8g in CAPD. In conclusion, the incidence of hypercalcemia is low in pre-HD (2.5%) and in CAPD patients(7.8%). However, the high incidence of post-HD hypercalcemia observed in this study advocates a future study to evaluate the effect of low calcium dialyste on calcium-phosphate metabolism.
Alkaline Phosphatase ; Aluminum ; Calcium ; Calcium Carbonate ; Dialysis* ; Humans ; Hypercalcemia* ; Incidence* ; Intestinal Absorption ; Korea ; Metabolism ; Parathyroid Hormone ; Peritoneal Dialysis, Continuous Ambulatory* ; Renal Dialysis ; Renal Osteodystrophy ; Retrospective Studies ; Serum Albumin

A large amount of alpha-ketoglutarate (alpha-KG) (6.8 g/L) was accumulated in flask culture when CaCO3 was used as a buffering agent in the production of pyruvate by multi-vitamin auxotrophic yeast Torulopsis glabrata CCTCC M202019. In a 5 L jar-fermentor, less alpha-KG (1.3 g/L) was produced when NaOH was used to adjust the pH, while more alpha-KG (11.5 g/L) detected when CaCO3 was used as the buffer. In the latter case, the molar carbon ratio of pyruvate to alpha-KG (C(PYR)/ CalphaKG) was similar to that obtained in flask culture, suggesting the accumulation of alpha-ketoglutarate was related to the addition of CaCO3. Furthermore, it was found that: (1) delaying the addition time of CaCO3 decreased the a-ketoglutarate formation but increased C(PYR)/ C(alphaKG); and (2) under vitamin limitation conditions increasing the concentration of CaCO3 led to an increased a-KG accumulation at the expenses of pyruvate. To study which ions in CaCO3 was responsible for the accumulation of alpha-KG, the effects of different pH buffers on the a-KG accumulation were studied. The level of alpha-KG was found to correlate with the levels of both Ca2+ and CO3(2-), with Ca2+ played a dominant role and CO3(2-) played a minor role. To find out which pathway was responsible for the accumulation of alpha-KG, the effects of biotin and thiamine on alpha-KG accumulation was investigated. The increase in biotin concentration led to an increase in alpha-KG accumulation and a decrease in C(PYR)/ C(alpha-KG), while the levels of alpha-KG and C(PYR)/C(alphaKG) were not affected by thiamine concentration. The activity of pyruvate carboxylase was increased as much as 40% when the medium was supplemented with Ca2+ . On the other hand, the activity of the pyruvate dehydrogenase complex was unaffected by the presence of Ca2+. To conclude, the higher level of a-KG was caused by higher activity of pyruvate carboxylase stimulated by Ca2+, with CO3(2-) served as the substrate of the reaction.
Biotechnology ; methods ; Calcium Carbonate ; pharmacology ; Candida glabrata ; drug effects ; metabolism ; Fermentation ; drug effects ; Ketoglutaric Acids ; metabolism ; Models, Biological ; Pyruvic Acid ; metabolism

BACKGROUND: Posttransplant osteoporosis in renal transplant recipient is frequently observed complications, but therapeutic modalities are not clearly elucidated. Recent studies indicate that vitamin K2 also play a role in bone metabolism. Therefore, we performed prospective study to evaluate the effect of vitamin K2 (Menatetrenone(R)) on posttransplant osteroporosis. METHODS: Our study included total 83 patients (40 male, 43 female; age 36.9+/-5.5 years) who received a renal transplant more than 6 months ago. They underwent dual-energy X-ray absorptiometry (DEXA) at lumbar spine and femoral neck. The patients with osteoporosis were treated with vitamin K2 (glakay 15 mg) (group 1) or vitamin D3 with calcium carbonate (group 2). The patients without osteoporosis was observed without any treatment (group 3). After one year, follow-up BMD was performed in all patients. RESULTS: Of 83 patients, 44 patients (53.0%) had osteoporosis and 39 patients (47.0%) had not. In group 1 (N=28), vitamin K2 treatment significantly increased BMD at femoral neck (-3.2+/-0.4 vs 2.6+/-0.6, p<0.05), but there was no increase of BMD at lumbar spine (-2.2+/-1.0 vs 2.2+/-0.9, p>0.05). In group 2 (N=16), there was significant increase in BMD at femoral neck (-3.0+/-0.6 vs -2.5+/-0.8, p< 0.05), but there was no increase of BMD at lumbar spine (-1.8+/-0.7 vs -1.8+/-0.8, p>0.05). Between group 1 and 2, there was no significant difference in BMD change. In group 3, BMD decreased at femoral neck (-1.3+/-0.2 vs -1.5+/-0.2) and lumbar spine (-0.8+/-0.2 vs -1.0+/-0.2) during follow-up period. CONCLUSION: Vitamin K2 (Menatetrenone(R)) is effective in treating osteoporosis at femoral neck and its effectiveness is s imilar with that of using vitamin D3 with calcium carbonate.
Absorptiometry, Photon ; Calcium Carbonate ; Cholecalciferol ; Female ; Femur Neck ; Follow-Up Studies ; Humans ; Male ; Metabolism ; Osteoporosis* ; Prospective Studies ; Spine ; Transplantation* ; Vitamin K 2

BACKGROUNDRenal osteodystrophy is one of the commonest complications of chronic renal failure. It may have a severe impact on the quality of life of patients on maintenance dialysis therapy. Besides post-menopausal women and elderly people, the dialysis patients are another high risk group. But at present, there is no research on how to prevent osteoporosis in maintenance dialysis patients. This study was conducted to observe the bone density of maintenance dialysis patients and to evaluate the clinical outcomes and safety of different administration dosage of salmon calcitonin to prevent osteoporosis in maintenance dialysis patients.

METHODSOne hundred and forty-eight patients on maintenance dialysis were involved in the 12-month, randomized, controlled trial. Fifty patients (experiment I group) received subcutaneous injection of salmon calcitonin (50 U) three times a week for 12 months. Fifty patients (experiment II group) received subcutaneous injection of salmon calcitonin (100 U) three times a week for 12 months. At the same time, both of them received oral calcium carbonate 1500 mg tid and rocaltrol 0.25 microg qn for 12 months. The control group only received oral calcium carbonate 1500 mg tid and rocaltrol 0.25 microg qn for 12 months. The levels of bone mass density (BMD) of the lumbar spine and femoral neck, serum intact parathyroid hormone (iPTH), osteocalcin (OC), calcium, phosphorus, alkaline phosphatase (ALP) were assessed at baseline and then again after 3, 6 and 12 months of treatment.

RESULTSThe values of BMD at the lumbar spine and femoral neck before the treatment were not significantly different from those 3, 6, and 12 months after the treatment in trial groups I and II (all P > 0.05) and there were no significant differences in the BMD values at different time points between trial groups I and II. In the control group, the BMD values at the lumbar spine and femoral neck 3, 6, and 12 months after the beginning of trial were significantly lower than those before the trial, and significantly lower than the corresponding values of trial groups I and II (all P < 0.05). The serum OC 3, 6, and 12 months after the treatment was significantly lower than that before the experiment (all P < 0.05) in the control group. However, there was no significant difference in the value of serum OC before and 3, 6, and 12 months after the treatment in trial groups I and II (all P > 0.05).

CONCLUSIONSThe dose of salmon calcitonin 50 U three times a week plus calcium carbonate and active vitamin D can effectively preserve the BMD and prevent bone loss in maintenance dialysis patients, and it is well tolerated by patients on maintenance dialysis.

Adult ; Alkaline Phosphatase ; blood ; Bone Density ; drug effects ; Bone Density Conservation Agents ; administration & dosage ; therapeutic use ; Calcitonin ; administration & dosage ; therapeutic use ; Calcium ; blood ; Calcium Carbonate ; administration & dosage ; therapeutic use ; Drug Administration Schedule ; Female ; Femur Neck ; drug effects ; metabolism ; Humans ; Lumbar Vertebrae ; drug effects ; metabolism ; Male ; Middle Aged ; Osteocalcin ; blood ; Osteoporosis, Postmenopausal ; blood ; prevention & control ; Parathyroid Hormone ; blood ; Phosphorus ; blood ; Renal Dialysis

OBJECTIVETo provide insights into the mechanisms and pathways of osteogensis by observing the effects of water-soluble matrix of nacre (WSM) on bone morphogenetic protein-2 (BMP-2) and Cbfa1 gene expressions in rabbit marrow mesenchymal stem cells (BMSCs).

METHODSNew Zealand rabbit BMSCs cultured in vitro were stimulated with different concentrations of WSM extracted at low temperature, and the activity of AKP in the cells was evaluated with the dose-effect curve generated. BMP-2 and Cbfa1 gene expressions in rabbit BMSCs exposed to WSM were assayed with one-step RT-PCR.

RESULTSThe activity of AKP in rabbit BMSCs increased after stimulation with different concentrations of WSM, and the effects were the most obvious with the WSM concentration ranging from 150 to 200 microg/ml. BMP-2 gene expression in the BMSCs increased after WSM exposure, but which did not result in obvious changes in Cbfa1 gene expression.

CONCLUSIONWSM induces differentiation of rabbit BMSCs towards osteoblasts by increasing BMP-2 gene expression, in which process Cbfa1 gene does not seem to play a significant role.

Animals ; Biological Factors ; pharmacology ; Bone Marrow Cells ; drug effects ; metabolism ; Bone Morphogenetic Protein 2 ; metabolism ; Calcium Carbonate ; pharmacology ; Cell Differentiation ; drug effects ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit ; metabolism ; Mesenchymal Stromal Cells ; drug effects ; metabolism ; Rabbits ; Reverse Transcriptase Polymerase Chain Reaction