Spermatogonial stem cells: unlimited potential

Recent reports have demonstrated that adult cells can be reprogrammed to pluripotency, but mostly with genes delivered using retroviruses. Some of the genes are cancer causing; thus, these adult-derived embryonic stem (ES)-like cells cannot be used for therapy to cure human diseases. Remarkably, it has also been demonstrated recently by several groups that, in mice, spermatogonial stem cells (SSCs) can be reprogrammed to ES-like cells without the necessity of exogenously added genes. SSCs constitute one of the most important stem cell systems in the body, not only because they produce spermatozoa that transmit genetic information from generation to generation, but also because of the recent studies showing their remarkable plasticity. Very little is known about SSCs in humans, except for the earlier work of Clermont and colleagues who demonstrated that there are Adark and Apale spermatogonia, with the Adark referred to as the reserve stem cells and the Apale being the renewing stem cells. We now demonstrate that G protein-coupled receptor 125 (GPR125) may be a marker for human SSCs. Putative human SSCs can also be reprogrammed to pluripotency. We were able to achieve this result without the addition of genes, suggesting that human SSCs have considerable potential for cell-based, autologous organ regeneration therapy for various diseases.

Comparative study of polyvinylidene fluoride and PES flat membranes in submerged MBRs to treat domestic wastewater

Two kinds of membranes, polyvinylidene fluoride (PVDF) and polyethersulfone (PES), were used in submerged flat membrane bioreactors (MBRs) to treat domestic wastewater in this study. The MBRs ran under the same reactor structure, the same membrane pore size of 0.45 mICROm and the same anoxic/ oxic (A/O) process. The experimental results showed that: (1) With the influent of BOD(5) 200-500 mg/L and COD(Cr) 400-1,000 mg/L, PVDF MBR achieved the removal efficiencies of BOD(5) 96-98% and COD(Cr) 89-98%, and those were 97-99% and 93-97% in PES MBR. The interceptive efficiency of PES membrane to BOD(5) and COD(Cr) was superior to PVDF membrane. (2) The removal efficiencies of TN and NH(3)-N in two MBRs exhibited good results which were greater than 85%. The removal efficiencies of TP were greater than 80% in both MBRs. (3) MLSS concentration changed from 2,000 mg/L to 7,000 mg/L during the experiment. PES membrane was not washed and the membrane flux was steady. However, the flux of PVDF one decreased quickly and was washed for twice. It meant that PES membrane had fine capability than PVDF one.

Edge states and optical transition energies in carbon nanoribbons

The edge states and optical transition energies in carbon nanoribbons are investigated with density-functional calculations. While the ground state of zigzag ribbons is spin polarized, defects at the edges destroy spin polarization and lead to a nonmagnetic ground state. Scanning tunneling spectroscopy will thus show different features depending on edge quality. Optical transition energies in nanoribbons Eii are strongly affected by the edges and confinement, which introduce a term inversely proportional to their width. After removing that term, the scaling of Eii is quantitatively similar to that in carbon nanotubes.

Statins decrease the aberrant HLA-DR expression on thyrocytes from patients with Hashimoto's thyroiditis

Statins have been found to exert anti-inflammatory and immune modulatory effects. It seems likely that these drugs may improve thyroid function in patients with Hashimoto's thyroiditis (HT). The objective of our study was to investigate the effect of statins on HLA-DR (human leukocyte antigen D-related) expression of thyrocytes from patients with HT hypothyroidism. Thyroid tissues were obtained from surgical specimens. Thyrocytes were cultured in the presence or absence of IFN-gamma (50 ng/ml) with or without statins (simvastatin 10 microM or atorvastatin 10 microM) for 72 hours. HLA-DR expression was detected by flow cytometry. Normal thyrocytes were used for controls. HLA-DR expression of HT thyrocytes was much higher than that of normal thyrocytes (41.2+/-4.5% vs. 2.7+/-2.1%, p<0.01), which could be further increased by IFN-gamma stimulation in both groups (p<0.01). However, simvastatin and atorvastatin could significantly inhibit the "aberrant" HLA-DR expression on HT thyrocytes and decrease IFN-gamma- induced HLA-DR expression in both HT and normal thyroid cells (p<0.01). Statins can repress HLA-DR expression of HT thyrocytes, which might inhibit the subsequent lymphocyte activation and ameliorate the immune disturbance of HT.

In vivo characterization of transplanted human embryonic stem cell-derived pancreatic endocrine islet cells

OBJECTIVES

Islet-like clusters (ILCs), differentiated from human embryonic stem cells (hESCs), were characterized both before and after transplantation under the kidney capsule of streptozotocin-induced diabetic immuno-incompetent mice.

MATERIALS AND METHODS

Multiple independent ILC preparations (n = 8) were characterized by immunohistochemistry, flow cytometry and cell insulin content, with six preparations transplanted into diabetic mice (n = 42), compared to controls, which were transplanted with either a human fibroblast cell line or undifferentiated hESCs (n = 28).

RESULTS

Prior to transplantation, ILCs were immunoreactive for the islet hormones insulin, C-peptide and glucagon, and for the ductal epithelial marker cytokeratin-19. ILCs also had cellular insulin contents similar to or higher than human foetal islets. Expression of islet and pancreas-specific cell markers was maintained for 70 days post-transplantation. The mean survival of recipients was increased by transplanted ILCs as compared to transplanted human fibroblast cells (P < 0.0001), or undifferentiated hESCs (P < 0.042). Graft function was confirmed by secretion of human C-peptide in response to an oral bolus of glucose.

CONCLUSIONS

hESC-derived ILC grafts continued to contain cells that were positive for islet endocrine hormones and were shown to be functional by their ability to secrete human C-peptide. Further enrichment and maturation of ILCs could lead to generation of a sufficient source of insulin-producing cells for transplantation into patients with type 1 diabetes.

The in vitro characterization of polyene glycosyltransferases AmphDI and NysDI

The overproduction, purification, and in vitro characterization of the polyene glycosyltransferases (GTs) AmphDI and NysDI are reported. A novel nucleotidyltransferase mutant (RmlA Q83D) for the chemoenzymatic synthesis of unnatural GDP-sugar donors in conjunction with polyene GT-catalyzed sugar exchange/reverse reactions allowed the donor and acceptor specificities of these novel enzymes to be probed. The evaluation of polyene GT aglycon and GDP-sugar donor specificity revealed some tolerance to aglycon structural diversity, but stringent sugar specificity, and culminated in new polyene analogues in which L-gulose or D-mannose replace the native sugar D-mycosamine.

Instrument for determining the complex shear modulus of soft-tissue-like materials from 10 to 300 Hz

Accurate determination of the complex shear modulus of soft tissues and soft-tissue-like materials in the 10-300 Hz frequency range is very important to researchers in MR elastography and acoustic radiation force impulse (ARFI) imaging. A variety of instruments for making such measurements has been reported, but none of them is easily reproduced, and none have been tested to conform to causality via the Kramers-Kronig (K-K) relations. A promising linear oscillation instrument described in a previous brief report operates between 20 and 160 Hz, but results were not tested for conformity to the K-K relations. We have produced a similar instrument with our own version of the electronic components and have also accounted for instrumental effects on the data reduction, which is not addressed in the previous report. The improved instrument has been shown to conform to an accurate approximation of the K-K relations over the 10-300 Hz range. The K-K approximation is based on the Weichert mechanical circuit model. We also found that the sample thickness must be small enough to obtain agreement with a calibrated commercial rheometer. A complete description of the improved instrument is given, facilitating replication in other labs.

Natriuretic Peptides, Antidiuretic Hormone and Hyponatraemia after Acute Craniocerebral Injury

We investigated the physiological mechanisms involved in central hyponatraemia in patients with acute craniocerebral injury (ACI). We measured blood concentrations of natriuretic peptides, antidiuretic hormone (ADH), and endogenous digitalis-like substance (EDLS), blood and urine sodium concentrations, and the plasma and urine osmolality in 68 patients with ACI and 24 healthy control subjects. A total of 27 ACI patients were hyponatraemic and the majority of these had grievous or severely grievous craniocerebral injuries. Blood concentrations of EDLS and ADH in hyponatraemic ACI patients were significantly higher compared with normonatraemic ACI patients and control subjects. Blood EDLS and sodium concentrations were negatively correlated with each other, whereas EDLS was positively correlated with urine sodium concentration and with urine osmotic pressure. Hyponatraemic ACI patients require different treatment based on the cause of their central hyponatraemia, so it is important to undertake a comprehensive analysis of each patient's physiological status.

A Frequent Partial AZFc Deletion does not Render an Increased Risk of Spermatogenic Impairment in East Asians

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.

Outcome of floppy Nissen fundoplication with intraoperative manometry to treat sliding hiatal hernia

The aim of this study was to evaluate the effectiveness of floppy Nissen fundoplication with intraoperative esophageal manometry. Between February 1992 and July 2004, there were 102 patients with sliding hiatal hernia undergoing transabdominal Nissen fundoplication. They were divided into three groups: 27 patients were in the Nissen group (CNF), 44 in the floppy Nissen group (FNF, including 5 with laparoscopic Nissen fundoplication), and 31 in the intraoperative-esophageal-manometry group (INF, 13 with laparoscopic Nissen fundoplication). There were no operation-related deaths. Operation-related complications occurred in five patients within 1 month after operation: In CNF, two patients suffered from dysphagia and one from regurgitation; in FNF, one patient had slight dysphagia and two had regurgitation; in INF, there was no one who complained about dysphagia or regurgitation, but pneumothorax occurred in one case. After more than 2 years of follow-up, two patients, in CNF, suffered from severe dysphagia, one recurred and two with abnormal 24 h pH monitoring. In FNF, one patient had dysphagia, one recurred and three had abnormal 24 h pH monitoring; in INF, two patients had acid reflux on 24 h pH monitoring. The postoperative lower esophageal sphincter pressure was in the normal range in 30 of 31 patients (96.5%). The normal rate of postoperative tests in CNF, FNF and INF were 81.5%, 86.4% and 93.5%, respectively. Both the Nissen fundoplication and the floppy Nissen fundoplication are effective approaches to treat patients with sliding hiatal hernia. Intraoperative manometry is useful in standardizing the tightness of the wrap in floppy Nissen fundoplication and may contribute to reducing or avoiding the occurence of postoperative complications.

C5 blockade with conventional immunosuppression induces long-term graft survival in presensitized recipients

We explored whether a functionally blocking anti-C5 monoclonal antibody (mAb) combined with T- and B-cell immunosuppression can successfully prevent antibody-mediated (AMR) and cell-mediated rejection (CMR) in presensitized murine recipients of life-supporting kidney allografts. To mimic the urgent clinical features of AMR experienced by presensitized patients, we designed a murine model in which BALB/c recipients were presensitized with fully MHC-mismatched C3H donor skin grafts one week prior to C3H kidney transplantation. Presensitized recipients demonstrated high levels of circulating and intragraft antidonor antibodies and terminal complement activity, rejecting grafts within 8.5 +/- 1.3 days. Graft rejection was predominantly by AMR, characterized by interstitial hemorrhage, edema and glomerular/tubular necrosis, but also demonstrated moderate cellular infiltration, suggesting CMR involvement. Subtherapeutic treatment with cyclosporine (CsA) and LF15-0195 (LF) did not significantly delay rejection. Significantly, however, the addition of anti-C5 mAb to this CsA/LF regimen prevented terminal complement activity and inhibited both AMR and CMR, enabling indefinite (>100 days) kidney graft survival despite the persistence of antidonor antibodies. Long-term surviving kidney grafts expressed the protective proteins Bcl-x(S/L) and A-20 and demonstrated normal histology, suggestive of graft accommodation or tolerance. Thus, C5 blockade combined with routine immunosuppression offers a promising approach to prevent graft loss in presensitized patients.

Bone marrow mesenchymal stem cells induce angiogenesis and attenuate the remodeling of diabetic cardiomyopathy

Independent of the severity of coronary artery disease, diabetic patients have an increased risk of developing heart failure. Diabetic cardiomyopathy (DCM) is characterized by microvascular pathologies and interstitial fibrosis. Mesenchymal stem cells (MSCs) are pluripotent and are able to differentiate into cardiomyocytes and vascular endothelial cells. Studies have demonstrated MSCs transplantation can prevent apoptosis of ischemic heart via upregulation of Akt and eNOS and inhibit myocardial fibrosis of dilated cardiomyopathy by decreasing the expression of matrix metalloproteinase (MMP) in rat models. In order to find out whether transplantation of MSCs is a promising treatment in DCM, we used streptozotocin (STZ) -induced diabetic rats as the model. Exogenous MSCs were injected into the femoral vein 8 weeks after STZ injection. Using independent experimental approaches, we showed that MSCs presented in the myocardium 4 weeks after transplantation and some of them were positive for the cardiac markers Troponin T and myosin heavy chain. MSCs transplantation significantly increased myocardial arteriolar density and decreased the collagen volume in diabetic myocardium resulting in improved cardiac function. Furthermore, MSCs transplantation increased MMP-2 activity and decreased transcriptional level of MMP-9. These results show that MSCs transplantation improved cardiac function in the rat DCM model, possibly through angiogenesis and attenuation of cardiac remodeling.