Multi-state, 4-aminopyridine-sensitive ion channels in human spermatozoa

Although ion channels are known to be pivotal to sperm function, the technical difficulty of applying electrophysiological techniques to spermatozoa has prevented significant progress in this area. This is due to the cell size and angular shape in combination with their motility. Using a refined technique, specifically for patch clamping spermatozoa, we have made recordings from human cells. This technique permitted approaches which enable functional analysis of sperm ion channels, including acquisition of inside-out patches, generation of averaged currents, and observation of the effects of pharmacological manipulation during prolonged recordings. As well as a low conductance (7 pS) channel and a 25-pS channel, the most striking finding was the presence of very high conductance, 4-aminopyridine-sensitive multistate channels resembling the non-selective cation channel of sea urchin and mouse spermatozoa. Application of 2 mM 4-aminopyridine (a dose sufficient to cause channel blockade) caused an instant and dramatic transition of motility in the sperm population increasing hyperactivated motility by more than 10-fold as assessed by computer-assisted semen analysis. Combined application of patch clamp and pharmacological investigation of mature sperm cells and will permit rapid advances in our understanding the role of ion channels in sperm function.

Quantitative fluorescence resonance energy transfer (FRET) measurement with acceptor photobleaching and spectral unmixing

Fluorescence resonance energy transfer (FRET) by acceptor photobleaching is a simple but effective tool for measurements of protein-protein interactions. Until recently, it has been restricted to qualitative or relative assessments owing to the spectral bleed-through contamination resulting from fluorescence overlap between the donor and the acceptor. In this paper, we report a quantitative algorithm that combines the spectral unmixing technique with FRET by acceptor photobleaching. By spectrally unmixing the emissions before and after photobleaching, it is possible to resolve the spectral bleed-through and retrieve the FRET efficiency/interaction distance quantitatively. Using a human keratinocyte cell line transfected with cyan fluorescent protein (CFP)- and yellow fluorescent protein (YFP)-tagged Cx26 connexins as an example, FRET information at homotypic gap junctions is measured and compared with well-established methods. Results indicate that the new approach is sensitive, flexible, instrument independent and solely FRET dependent. It can achieve FRET estimations similar to that from a sensitized emission FRET method. This approach has a great advantage in providing the relative concentrations of the donor and the acceptor; this is, for example, very important in the comparative study of cell populations with variable expression levels.

Induction of apoptosis in proliferating lymphocytes by tricyclic antidepressants

We have previously found that tricyclic antidepressants (TCAs) induce apoptosis in quiescent human lymphocytes. The aim of the present study was to evaluate if TCAs induce apoptosis in proliferating human lymphocytes and in established blastoid lymphocytes also. The development of conA-induced lymphoblast populations was followed by measuring the CD25 membrane expression. Three TCA compounds were run with the following concentrations: imipramine (10, 20, 30, 40, 60 microM), clomipramine (1, 10, 20, 30, 40 microM) and citalopram (40, 60, 80, 100, 180 microM). They all induced a dose-dependent apoptosis both in continuously transformed, as well as in established lymphoblasts. Preincubation of the TCA up to 48 h did not significantly increase induction of apoptosis. The three drugs tested were found to be potent inducers of apoptosis in proliferating lymphocytes. Furthermore, we found that the apoptotic populations in proliferating and in established blastoid lymphocytes were of fairly the same magnitude than in the corresponding population in TCA-incubated resting lymphocytes. In conclusion, we demonstrate that TCAs induce apoptosis in proliferating lymphocytes, as they do in quiescent lymphocytes. Furthermore, the extent of apoptosis was even more pronounced in TCA-incubated lymphoblasts compared to TCA-treated resting lymphocytes.

Photodynamic therapy of esophageal varices: experimental studies in animal veins, and first clinical cases

BACKGROUND AND STUDY AIMS

Endoscopic injection sclerotherapy and endoscopic variceal ligation have been found to have shortcomings in the treatment of esophageal varices. In this study the effectiveness of photodynamic therapy (PDT) in the obliteration of veins was investigated to evaluate its potential in the treatment of esophageal varices.

METHODS

Auricular margin veins of rabbits were irradiated by copper vapor laser after intravenous injection of 10 mg/kg of hematoporphyrin monomethyl ether (which is a hematoporphyrin derivative) into the rabbits. Control groups included rabbits that received irradiation only, that received injection of photosensitizer only, and that received injection sclerotherapy (using sodium morrhuate). The treated areas were observed macroscopically and also identified using with ultrasonic miniprobe. Biopsies were performed and the specimens were examined microscopically after hematoxylin-eosin staining and Victoria blue staining. In addition, two patients with newly visible veins within the esophageal wall after endoscopic injection sclerotherapy underwent PDT. Intravenous injection of 5 mg/kg of hematoporphyrin monomethyl ether was given, and the newly visible veins were endoscopically irradiated by copper vapor laser. Endoscopic re-examination was performed 1 month later to evaluate the therapeutic effect.

RESULTS

Thrombi of the auricular margin vein were formed and blood flow was obstructed after PDT. Thrombus formation and diffused necrosis of adjacent tissue was found after injection of sodium morrhuate. On ultrasonic examination, the lumina of the veins showed a slightly higher echo after PDT compared with a lower echo before treatment, which was another sign of thrombus formation. The rabbit ears showed a diffused low echo after injection of sodium morrhuate, indicating diffuse necrosis. On microscopic observation, destruction of the endothelium and formation of thrombus was seen after PDT. Further observation of specimens stained with Victoria blue showed that the layer of elastic fiber was intact. After injection of sodium morrhuate, extensive necrosis of tissue was seen microscopically. No macroscopic, ultrasonic, or microscopic change was found in the rabbits that received irradiation only or injection of photosensitizer only. The rate of thrombus formation in rabbits that received PDT was significantly higher than that in the rabbits that received irradiation only or injection of photosensitizor only ( P = 0.015, P = 0.015), and comparable to that in the rabbits that received sclerotherapy ( P = 0.467). In the clinical study, at endoscopy 1 month after PDT both the number and the "red sign" of newly visible veins were found to have decreased. No adverse effect was found.

CONCLUSION

PDT can destroy the endothelium of the vein, result in thrombus formation, and eventually obliterate the vein. It is potentially a new method for the treatment of esophageal varices.

FMR2 function: insight from a mouse knockout model

The FMR2 gene is dysregulated by the fragile X E triplet repeat expansion in patients with FRAXE mental retardation syndrome. A CCG triplet, located in the 5' untranslated region of the FRAXE gene undergoes expansion and methylation in these patients, eliminating detectable gene transcription. FRAXE syndrome is distinct from fragile X syndrome, a more common genetic form of mental retardation caused by expansion and methylation of a similar repeat in the FMR1 gene located 600 kb proximal to FRAXE. FRAXE syndrome is rare, and patients' phenotypes are highly variable, leading to difficulties with predicting specific FMR2 functions based on the human disease. Recently, Lilliputian(Lilli), a Drosophila FMR2 orthologue, was identified; this gene has been linked with several signal transduction pathways, including the transforming growth factor-beta (TGF-beta) pathway, the Raf/MEK/MAP kinase (MAPK) pathway, and the P13K/PKB pathway. Mutation of Lilli shows defects in germinal band extension, cytoskeletal structure, cell growth, and organ development. The Lilli gene suggests possible functions for FMR2 (and related genes) in humans and mice, but cannot predict specific functions. Modeling FMR2 mutation in the mouse will be useful to understand specific functions of this gene in vertebrates. This review presents what has been learned thus far from the FMR2 knockout mouse model and suggests future studies on this model in order to compare it with the human FRAXE mental retardation disorder, Lilli mutants in Drosophila and other mouse models of genes in this family.

In vivo high-efficiency transcoronary gene delivery and Cre-LoxP gene switching in the adult mouse heart

High-efficiency somatic gene transfer in adult mouse heart has not yet been achieved in vivo. Here, we demonstrate high-efficiency in vivo transcoronary gene delivery to the adult murine myocardium using a catheter-based technique with recombinant adenovirus (AdV) and adeno-associated virus (AAV) vectors in normal and genetically engineered mice. The method involves immersion hypothermia followed by transient aortic and pulmonary artery occlusion with proximal intra-aortic segmental injection of cardioplegic solution containing substance P and viral vectors. Gene expression measured using a LacZ marker gene was observed throughout both ventricles. The expression efficiency of a cytoplasmic LacZ marker gene in the left ventricular myocardium was 56.4+/-14.5% (mean+/-s.d.) at 4 days with an AdV vector, and with an AAV vector it was 81.0+/-5.9% at 4 weeks. Following AAV gene transfer, no gene expression was found in kidney, brain, lung, and spleen, but there was slight expression in liver. In addition, we demonstrate temporally controlled genetic manipulation in the heart with an efficiency of 54.6+/-5.2%, by transferring an AdV vector carrying Cre recombinase in ROSA26 flox-LacZ reporter mice. Procedure-related mortality was 16% for AdV and zero for AAV transfer. Thus, this method provides efficient, relatively homogeneous gene expression in both ventricles of the adult mouse heart, and offers a novel approach for conditional gene rescue or ablation in genetically engineered mouse models.

Protease chymotrypsin mediates the endothelial expression of P- and E-selectin, but not ICAM and VCAM, induced by placental trophoblasts from pre-eclamptic pregnancies

OBJECTIVES

Soluble endothelial-cell adhesion molecules (ICAM, VCAM and PECAM) are markers of endothelial activation, and are elevated in the maternal circulation during pregnancy and even further increased in pregnancies complicated by pre-eclampsia (PE). To identify possible sources of endothelial activators during pregnancy, we addressed whether factors released from placental trophoblast cells (TCs) activate endothelial cells (ECs) to enhance adhesion molecule expression on ECs. We also examined whether proteases released by placental cells induce the endothelial cell surface molecule expression in PE.

METHODS

Confluent ECs were co-cultured with placental TCs derived from normal (n=9) or PE (n=8) pregnancies or with placental conditioned media (CM) derived from PE placental cultures (n=7). ICAM, VCAM, P-selectin and E-selectin were quantified using an enzyme-linked immunosorbent assay (ELISA). The protease inhibitors alpha(2)-macroglobulin (alpha(2)M), thrombin inhibitor (TI) and chymotrypsin inhibitor (CI) were tested in the co-culture system. mRNAs for ICAM, VCAM, P-selectin and E-selectin were determined by RNase protection assay (RPA). NF-kappaB activity in ECs was also determined.

RESULTS

(1) ICAM and VCAM expression was significantly increased on ECs co-cultured with both normal-TCs and PE-TCs, compared to control ECs (P<0.01). ICAM and VCAM expression in ECs co-cultured with normal-TCs did not differ from ECs co-cultured with PE-TCs. (2) E-selectin expression was increased on ECs co-cultured with normal-TCs (P<0.05) and further increased in ECs co-cultured with PE-TCs (P<0.01). (3) P-selectin expression was increased on ECs co-cultured with PE-TCs, but not ECs co-cultured with normal-TCs compared to control ECs (P<0.05). (4) alpha(2)M and TI did not alter the ICAM, VCAM, P-selectin and E-selectin expression on ECs induced by PE-CM. (5) CI blocked the upregulation of P-selectin and E-selectin (P<0.05), but not ICAM and VCAM expression, in ECs cultured with PE-CM. (6) Changes in mRNA for ICAM, VCAM, P-selectin and E-selectin paralleled the increases in protein expression on ECs cultured with PE-CM. (7) NF-kappaB activity was also increased in cells challenged with PE-CM.

CONCLUSIONS

(1) Factor(s) released from both normal-TCs and PE-TCs promote ICAM and VCAM expression on ECs. (2) Factor(s) released from PE-TCs significantly increase EC P-selectin and E-selectin expression. (3) CI blocks the upregulation of P-selectin and E-selectin on ECs induced by factors released from PE placental cells, suggesting that chymotrypsin is responsible for the increased endothelial expression of P-selectin and E-selectin in pre-eclampsia.

Construction and characterization of a half million clone BAC library of durum wheat ( Triticum turgidum ssp. durum)

Durum wheat ( Triticum turgidum ssp. durum, 2 n = 4 x = 28, genomes AB) is an economically important cereal used as the raw material to make pasta and semolina. In this paper we present the construction and characterization of a bacterial artificial chromosome (BAC) library of tetraploid durum wheat cv. Langdon. This variety was selected because of the availability of substitution lines that facilitate the assignment of BACs to the A and B genome. The selected Langdon line has a 30-cM segment of chromosome 6BS from T. turgidum ssp. dicoccoides carrying a gene for high grain protein content, the target of a positional cloning effort in our laboratory. A total of 516,096 clones were organized in 1,344 384-well plates and blotted on 28 high-density filters. Ninety-eight percent of these clones had wheat DNA inserts (0.3% chloroplast DNA, 1.4% empty clones and 0.3% empty wells). The average insert size of 500 randomly selected BAC clones was 131 kb, resulting in a coverage of 5.1-fold genome equivalents for each of the two genomes, and a 99.4% probability of recovering any gene from each of the two genomes of durum wheat. Six known copy-number probes were used to validate this theoretical coverage and gave an estimated coverage of 5.8-fold genome equivalents. Screening of the library with 11 probes related to grain storage proteins and starch biosynthesis showed that the library contains several clones for each of these genes, confirming the value of the library in characterizing the organization of these important gene families. In addition, characterization of fingerprints from colinear BACs from the A and B genomes showed a large differentiation between the A and B genomes. This library will be a useful tool for evolutionary studies in one of the best characterized polyploid systems and a source of valuable genes for wheat. Clones and high-density filters can be requested at http://agronomy.ucdavis.edu/Dubcovsky/BAC-library/BAC_Langdon.htm

Fourier-transform Raman and infrared spectroscopic analysis of 2-nitro-tetraphenylporphyrin and metallo-2-nitro-tetraphenylporphyrins

The Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectra of 2-nitro-tetraphenylporphyrin (2-NO(2)-TPP), nickel-2-nitro-tetraphenylporphyrin (Ni-2-NO(2)-TPP), zinc-2-nitro-tetraphenylporphyrin (Zn-2-NO(2)-TPP) and copper-2-nitro-tetraphenylporphyrin (Cu-2-NO(2)-TPP) were acquired for the first time and carefully assigned and discussed. The effects of a beta-NO(2) group and the influence of the central metal on the molecular symmetry and vibrational spectra of the porphyrin macrocycle were also examined. The bands at 1323-1339, 1516-1526 and 961-971 cm(-1) were attributed to the symmetric and asymmetric stretching vibration of the NO(2) group and to the stretching vibration of the C(beta)-N bond, respectively, which connects the NO(2) group with the beta-carbon of the porphyrin macrocycle. These bands can act as a marker to distinguish beta-NO(2) TPPs from other beta-substituent TPPs. Cu-2-NO(2)-TPP has a C(4nu) molecular symmetry, which is different from those of Ni-2-NO(2)-TPP and Zn-2-NO(2)-TPP, i.e. D(4h).

Applications of Weak Gel for In-Depth Profile Modification and Oil Displacement

Abstract

Water breakthrough is a common problem when an oil field is waterflooded. Polymer solutions are widely applied to resolve the water channeling problem in deep formations. In practice, polymers are used in deep formation treatments either to block in-depth high permeability zones or to improve the mobility ratio. However, the major challenge for in-depth profile modification is how to deliver the gelling solution to the target zones. To this end, a polymer solution has to be injected at a high concentration. Thus, such a treatment sometimes becomes uneconomical. On the other hand, polymer flooding is ineffective primarily due to the viscosity loss caused by mechanical and chemical degradation. In this paper, a weak gel system is developed and used as an in-depth profile modification agent and as an oil displacement agent in a heterogeneous reservoir. The gel system has relatively low strength but can still be crosslinked in the reservoir formation. In comparison with a pure polymer solution, it suffers from less mechanical and chemical degradation because of its crosslink reaction. The EOR mechanisms of the weak gel system are described briefly. The detailed effects of polymer concentration, crosslinker concentration, temperature, and pH on gelation time are studied. Also the rheological properties, gelation range, and gel strength are examined. The coreflood results provide experimental evidence that the weak gel acts both as an in-depth profile modification agent and as an oil displacement agent. Furthermore, pilot tests have been performed in the Gudong and the Gudao oil fields of the Shengli oil field in China since 1992. The cummulative incremental oil production has been over 58,000 tonnes at the end of 2001.

Introduction

Waterflooding is the most widely used technology for improving oil recovery. However, early water breakthrough is a common problem encountered in almost every waterflooded oil field. Severe water channeling can result in low waterflooding efficiency and sometimes even make waterflooding uneconomical. There are several reasons for water breakthrough. Sometimes, it happens near the wellbore region, such as breakthrough along the casing due to poor cementing quality. In other cases, water breakthrough occurs in a deep formation because of its heterogeneity or fractures. In addition, because of the mobility difference between the displacing phase and the displaced phase, the former tends to bypass the latter in a homogeneous formation. In this case, viscous fingering is inevitable and early water breakthrough occurs in the producers(1–3). Different technologies have been implemented to reduce the high water-cut caused by water breakthrough, among which the most widely used is polymer injection. In general, polymer is increasingly used in chemical EOR in two traditional ways: either as an in-depth profile modification agent in conformance control, or as an oil displacement agent in polymer flooding.

For conformance control, polymer and crosslinker are injected into formations to reduce large channeling through fractures or high permeability zones without damaging the productivity of the hydrocarbon. However, due to the prompt crosslink reaction, gel is sometimes formed near the wellbore.

Adeno-associated viral transfer of opioid receptor gene to primary sensory neurons: a strategy to increase opioid antinociception

To develop a genetic approach for the treatment of pain, we introduced a recombinant adeno-associated viral (rAAV) vector containing the cDNA for the mu-opioid receptor (muOR) into primary afferent neurons in dorsal root ganglia (DRGs) of rats, which resulted in a long-lasting (>6 months) increase in muOR expression in DRG neurons. The increase greatly potentiated the antinociceptive effects of morphine in rAAV-muOR-infected rats with and without inflammation. Perforated patch recordings indicated that the efficacy and potency of opioid inhibition of voltage-dependent Ca(2+) channels were enhanced in infected neurons, which may underlie the increase in opiate efficacy. These data suggest that transfer of opioid receptor genes into DRG cells with rAAV vectors may offer a new therapeutic strategy for pain management.

Synthesis and SAR of bicyclic heteroaryl hydroxamic acid MMP and TACE inhibitors

Potent and selective bicyclic heteroaryl hydroxamic acid MMP and TACE inhibitors were synthesized by a novel convergent route. Selectivity and efficacy versus MMPs and TACE could be controlled by appropriate substitution on the scaffolds and by variation of the P1' group. Select compounds were found to be effective in in vivo models of arthritis.

Single-shot phase-stepped wide-field coherencegated imaging

We present a single-shot wide-field CCD based coherence-gated imaging technique that utilizes spatially separated phase-stepped images and requires only one CCD camera to achieve simultaneous acquisition of four phase-stepped images. This technique provides a relatively low cost system for depth-resolved imaging of dynamic samples. We demonstrate real-time coherence-gated imaging of a moving watch cog, 3D reconstructions of a coin, phase measurements of the surface of a test-chart and depth-resolved imaging in a weakly scattering sample of onion.

Identification of the anterior and posterior portions of the lateral pedicle cortex by roentgenograms in pedicle screw fixation

Forty lumbar pedicles and pedicle screws in four cadavers were used to identify the anterior and posterior portions of the lumbar pedicle cortex by roentgenograms in order to evaluate the penetration of the pedicle cortex by pedicle screws intraoperatively. Firstly, the transverse pedicle angles were measured on roentgenograms. Three roentgenograms were taken on each pedicle in three different directions: (1). medial to the pedicle axis; (2). pedicle axis; (3). lateral to the pedicle axis. They revealed that the anterior portion of the lateral pedicle cortex was demonstrated by the pedicle lateral outline on the roentgenogram medial to the pedicle axis, and the posterior portion by the pedicle lateral outline on the roentgenogram lateral to the pedicle axis. Wire markers were used to confirm these data. Finally, anterior and/or posterior penetrations on the lateral pedicle cortex in pedicle screw fixation were studied by roentgenograms in these cadavers and showed that anterior penetration of lateral cortex was demonstrated by the view medial to the pedicle axis, and posterior penetration by the view lateral to the pedicle axis. It is concluded that projections medical and lateral to the pedicle axis are necessary to identify lateral screw penetration intraoperatively when X-ray checking is used.

Repair of oxidative DNA damage: mechanisms and functions

Cellular genomes suffer extensive damage from exogenous agents and reactive oxygen species formed during normal metabolism. The MutT homologs (MutT/MTH) remove oxidized nucleotide precursors so that they cannot be incorporated into DNA during replication. Among many repair pathways, the base excision repair (BER) pathway is the most important cellular protection mechanism responding to oxidative DNA damage. The 8-oxoG glycosylases (Fpg or MutM/OGG) and the MutY homologs (MutY/MYH) glycosylases along with MutT/MTH protect cells from the mutagenic effects of 8-oxoG, the most stable and deleterious product known caused by oxidative damage to DNA. The key enzymes in the BER process are DNA glycosylases, which remove different damaged bases by cleavage of the N-glycosylic bonds between the bases and the deoxyribose moieties of the nucleotide residues. Biochemical and structural studies have demonstrated the substrate recognition and reaction mechanism of BER enzymes. Cocrystal structures of several glycosylases show that the substrate base flips out of the sharply bent DNA helix and the minor groove is widened to be accessed by the glycosylases. To complete the repair after glycosylase action, the apurinic/apyrimidinic (AP) site is further processed by an incision step, DNA synthesis, an excision step, and DNA ligation through two alternative pathways. The short-patch BER (1-nucleotide patch size) and long-patch BER (2-6-nucleotide patch size) pathways need AP endonuclease to generate a 3' hydroxyl group but require different sets of enzymes for DNA synthesis and ligation. Protein-protein interactions have been reported among the enzymes involved in BER. It is possible that the successive players in the repair pathway are assembled in a complex to perform concerted actions. The BER pathways are proposed to protect cells and organisms from mutagenesis and carcinogenesis.

[Cardiac pathological study of sudden death due to myocarditis: analysis of 17 cases]

17 cases of sudden death due to myocarditis were presented. The problem of the classification and mechanism of sudden death is discussed. It is concluded that heart function failure is the main reason for the sudden death of myocarditis.

Effect of basic fibroblast growth factor on insulin secretion from microencapsulated pancreatic islets: an in vitro study

Microencapsulation of pancreatic islets represents a potentially effective method to prevent graft rejection in allotransplantation or xenotransplantation without the need of immunosuppression. Adequate insulin secretion and glucose responsiveness of microencapsulated pancreatic islets has been regarded as a prerequisite for successful transplantation. The microencapsulated pancreatic islets were respectively cultured in bFGF+ RPMI-1640 medium (bFGF+) or bFGF- RPMI-1640 medium (bFGF-) for 21 days. The functional activities of microencapsulated pancreatic islets were assessed by measuring basal insulin secretion and stimulated insulin release at different time points. The results revealed that microencapsulated pancreatic islets in the presence of bFGF demonstrated an increase in basal insulin secretion. Furthermore, microencapsulated pancreatic islets in the presence of bFGF demonstrated a marked stimulated insulin release and relative stability of stimulation indices (SI). The results in the perifusion study showed that microencapsulated pancreatic islets in the presence of bFGF maintained good glucose responsiveness over the course of culture period as well. These results indicate that bFGF has a beneficial effect on insulin secretion from microencapsulated pancreatic islets during in vitro culture. New strategies for preserving and improving function of microencapsulated pancreatic islets prior to transplantation may be developed by application of growth factors or other factors.

Regulation of cell proliferation using tissue engineering in MIN6 cells

Pancreatic islet transplantation for patients with diabetes mellitus has been hindered by the problem of donor shortage, as is the case for transplantation of other organs. Among several measures to overcome this problem, cell transplantation using xenogenic cell lines has been considered. For the treatment of diabetic patients, a murine pancreatic beta-cell line MIN6 is a potential source of cell transplant. In order to restrict otherwise unlimited proliferation of transplanted MIN6 cells, cells are rendered to form spheroidal aggregates (SMIN6) on nonadherent culture dishes. SMIN6 stopped its growth around day 7 with a diameter of 220 +/- 40 microm and kept its size almost constant at least until day 28. SMIN6 cells, however, had reduced responsiveness of insulin secretion to glucose concentration compared with MIN6 cells cultured in a monolayer. On the other hand, spheroid MIN6 cells formed in the presence of extracellular matrix gel (SMIN6E) possessed the capacity for glucose-dependent insulin secretion comparable with conventional MIN6 cells. SMIN6E encapsulated in agarose beads (SMIN6E-B) was also viable for at least 1 month in vitro with a constant diameter and favorable glucose responsiveness. The development of spheroid-type MIN6 may contribute to the future clinical application of MIN6 or other beta-cell lines for treatment of diabetes mellitus.

The influence of the anticomplement synthetic sulfonic polymers on the function of pancreatic islets: an in vitro study

In a previous experiment, we demonstrated the anticomplementary efficacy of poly(stryrene sulfonic acid) (PSSa) and poly(2-acrylamido-2-methyl propane sulfonic acid) (PAMPS). The aim of this study was to examine their influence on the function of pancreatic islets in vitro. In this study, after culturing the rat islets with RPMI-1640 culture medium containing different concentrations of soluble PSSa or PAMPS for 24 h at 37 degrees C, we performed morphological and functional examination of the rat islets. We found that the islets maintained their normal morphology regardless of whether they were in the PSSa or PAMPS groups when the concentrations of soluble PSSa or PAMPS in the media were below 1 g/dl. In the static incubation study, the islets cultured in the PAMPS groups showed significantly high insulin secretory response to glucose challenge but those in the PSSa groups lost the response when the concentrations of soluble PSSa or PAMPS in the media were below 1 g/dl. The PAMPS not only had strong anticomplementry effect, but also maintained the good insulin secretory capacity of the islets. These results indicated that PAMPS is a promising bioartificial material for future clinical application of biohybrid artificial pancreas preparation. It is well suitable for xenotransplantation experiments.

Evaluation of insulin secretion of isolated rat islets cultured in extracellular matrix

Islet isolation involves enzymatic digestion of the interstitial matrix and mechanical disruption of the tissue. It is possible that a fundamental change of islet biology resulting from the loss of critical factors required for islet function or survival will occur. Extracellular matrix (ECM) is one of the most important components of the islet microenvironment. Reconstruction of the cell-matrix relationship seems to be effective for improving the loss of differentiated islet structure and function. The purpose of this study was to characterize and compare the effects of collagen gel mixture or Matrigel on beta-cell function and islet cell survival. After isolation by the collagenase digestion technique, rat islets were divided and cultured with various types of collagen gel mixture. They were assessed for their glucose-stimulated insulin secretion and cell viability. Glucose-induced insulin secretion of islets cultured with collagen type I gel or a mixture of collagen type I and IV was improved after 11 days in culture. In conclusion, a type of gel composed of collagen type I and/or type IV as an islet microenvironment is sufficient to maintain glucose responsiveness and may be useful for islet transplantation.