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.

Development of a new method to induce angiogenesis at subcutaneous site of streptozotocin-induced diabetic rats for islet transplantation

The subcutaneous space is a potential site for clinical islet transplantation. Even though there are several advantages, poor blood supply at this site mainly causes failure of islet survival. In this study, angiogenesis was induced in advance at the diabetic rats subcutis for islet transplantation by implanting a polyethylene terephthalate (PET) mesh bag containing gelatin microspheres incorporating basic fibroblast growth factor (bFGF) (MS/bFGF) and a collagen sponge. The bFGF was incorporated into gelatin microspheres for controlled release of bFGF. As controls, a PET mesh bag with or without either collagen sponges or MS/bFGF was implanted at the subcutaneous site of diabetic rats. Macroscopic and microscopic examinations revealed the formation of capillary network in and around the PET mesh bag containing MS/bFGF and collagen sponges 7 days after implantation when compare with other control groups. When tissue hemoglobin level was also measured, a significantly high level of hemoglobin amount was observed compared with that of control groups. When allogeneic islets mixed with 5% agarose were transplanted into the prevascularized rat subcutis, normoglycemia was maintained for more than 40 days, while other control groups were ineffective. This study demonstrated that combination of gelatin microspheres incorporating bFGF and collagen sponges enabled the mesh to induce neovascularization even at the subcutaneous site of streptozotocin-induced diabetic rats, resulting in improved function of islet transplantation.

Statistics of level spacing of geometric resonances in random binary composites

We study the statistics of level spacing of geometric resonances in the disordered binary networks. For a definite concentration p within the interval [0.2,0.7], numerical calculations indicate that the unfolded level spacing distribution P(t) and level number variance Sigma(2)(L) have general features. It is also shown that the short-range fluctuation P(t) and long-range spectral correlation Sigma(2)(L) lie between the profiles of the Poisson ensemble and Gaussion orthogonal ensemble. At the percolation threshold p(c), crossover behavior of functions P(t) and Sigma(2)(L) is obtained, giving the finite size scaling of mean level spacing delta and mean level number n, which obey the scaling laws, delta=1.032L(-1.952) and n=0.911L(1.970).

The NMDA type glutamate receptors expressed by primary rat osteoblasts have the same electrophysiological characteristics as neuronal receptors

Cells of mammalian bone express glutamate receptors. Functional N-methyl-D-aspartate (NMDA) receptors have been demonstrated in human, osteoblastic MG-63 cells, but currents in these cells, unlike those of mammalian neurons, are blocked by Mg(2+) in a voltage-insensitive manner. Differences between the characteristics of NMDA currents in bone cells and in neurons may reflect molecular variation of the receptors or associated molecules, with implications for the role(s) of glutamate in these different tissues and for targeting of ligands/antagonists. To determine whether NMDA receptors in primary bone cells are functional, and whether the currents carried by these receptors resemble those of MG-63 cells or those of mammalian neurons, we have applied the whole cell patch clamp technique to primary cultures of rat osteoblasts. In 0-Mg(2+) saline, 25% of cells showed a slowly developing inward current in response to bath perfusion with 1 mM or 100 microM NMDA. Antibodies against NMDA receptors stained approximately 26% of cells. When NMDA was applied by rapid superfusion, kinetics of the currents were similar to those of neuronal NMDA currents, reaching a peak within 20-30 ms. 1 mM Mg(2+) reduced current amplitude at negative holding potentials and caused the I-V relationship of the currents to adopt a 'J' shape rather than the linear relationship seen in the absence of added Mg(2+). Co-application of glycine (20 microM) with NMDA increased current amplitude by only 18%, suggesting that glycine is released from cells within the cultures. Currents were blocked by (+)-MK-801 and DL-2-amino-5-phosphonovaleric acid. Fluorimetric monitoring of [Ca(2+)](i) using fura-2 showed that, in Mg(2+)-free medium, NMDA caused a sustained rise in [Ca(2+)](i) that could be reversed by subsequent application of MK-801. We conclude that rat femoral osteoblasts express functional NMDA receptors and that these receptors differ from those previously identified in MG-63 cells. NMDA receptors of primary osteoblasts show a 'classical' voltage-sensitive Mg(2+) block, similar to that seen in neuronal NMDA receptors, and will therefore function as detectors of coincident receptor activation and membrane depolarization.

A defect in the Kv channel-interacting protein 2 (KChIP2) gene leads to a complete loss of I(to) and confers susceptibility to ventricular tachycardia

KChIP2, a gene encoding three auxiliary subunits of Kv4.2 and Kv4.3, is preferentially expressed in the adult heart, and its expression is downregulated in cardiac hypertrophy. Mice deficient for KChIP2 exhibit normal cardiac structure and function but display a prolonged elevation in the ST segment on the electrocardiogram. The KChIP2(-/-) mice are highly susceptible to the induction of cardiac arrhythmias. Single-cell analysis revealed a substrate for arrhythmogenesis, including a complete absence of transient outward potassium current, I(to), and a marked increase in action potential duration. These studies demonstrate that a defect in KChIP2 is sufficient to confer a marked genetic susceptibility to arrhythmias, establishing a novel genetic pathway for ventricular tachycardia via a loss of the transmural gradient of I(to).

Fourier-transform Raman and infrared spectroscopic analysis of dipyrrinones and mesobilirubins

The Fourier-transform Raman (FT-Raman), infrared (FT-IR), and UV-visible absorption spectra of four dipyrrinones and two mesobilirubins have been investigated in the solid state and in CH2Cl2 solutions. A detailed spectral analysis, assignment and discussion of these spectra are presented. The bands at 1735-1738, 1691-1707 and 1359-1377 cm(-1) which were assigned to the stretching vibrations of the C-O-C and C-O-H and symmetric deformation of C-H bonds, respectively, can act as a marker to distinguish the compounds of this class. The striking differences between the spectra of the compounds suggest that mesobilirubin XIIIalpha is tending to adopt as ridge-tile conformation, rather than linear conformation.

Biosynthesis, characterisation, and design of bacterial exopolysaccharides from lactic acid bacteria

Lactic acid bacteria (LAB) are characterised by their conversion of a large proportion of their carbon feed, fermentable sugars, to lactic acid. However, in addition to lactic acid production, the LAB are able to divert a small proportion of fermentable sugars towards the biosynthesis of exopolysaccharides (EPSs) that are independent of the cell surface and cell wall material. These microbial EPSs when suspended or dissolved in aqueous solution provide thickening and gelling properties, and, as such, there is great interest in using EPSs from food grade microorganisms (such as the LAB that are traditionally used for food fermentations) for use as thickening agents. The current review includes a brief summary of the recent literature describing features of the biosynthetic pathways leading to EPS production. Many aspects of EPS biosynthesis in LAB are still not fully understood and a number of inferences are made regarding the similarity of the pathway to those involved in the synthesis of other cell polysaccharides, e.g., cell wall components. The main body of the review will cover practical aspects concerned with the isolation and characterisation of EPS structures. In the last couple of years, a substantial number of structures have been published and a summary of the common elements of these structures is included as is a suggestion for a system for representing structures. A brief highlight of the attempts that are being made to design 'tailor'-made polysaccharides using genetic modification and control of metabolic flux is presented.

Crystallization and preliminary X-ray diffraction analysis of shikimate kinase from Mycobacterium tuberculosis in complex with MgADP

Shikimate kinase (SK) from Mycobacterium tuberculosis (Mt) was overexpressed in Escherichia coli, purified and cocrystallized with MgADP in hanging drops using the vapor-diffusion procedure with PEG 4000 and 2-propanol as precipitants at pH 7.5. The crystal of MtSK-MgADP, which diffracted to 2.2 A resolution, belonged to space group P3(2)21 or P3(1)21, with unit-cell parameters a = b = 64.01, c = 92.41 A. There was one MtSK molecule in the asymmetric unit. Molecular-replacement trials with the crystal structure of SK from Erwinia chrysanthemi (PDB code 1shk) and adenylate kinase (PDB code 1ake) as search models were not successful. Heavy-atom derivative screening is in progress.

A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets

The plant-specific Rop family GTPases are versatile molecular switches in many processes during plant growth, development, and responses to the environment. To understand how Rop achieves its functional versatility in signaling, we performed a genome-wide identification of putative Rop targets using a combination of the yeast two-hybrid method, bioinformatic tools, and a robust functional assay in pollen. In this study, we have identified 11 Arabidopsis genes encoding novel proteins, termed RICs (for Rop-interactive CRIB motif-containing proteins), that contain a CRIB (for Cdc42/Rac-interactive binding) motif required for their specific interaction with GTP-bound Rop1. RICs are divergent and classified into five groups that share little sequence homology outside of the conserved Rop-interactive domain. Overexpression in tobacco pollen tubes of the nine Ric genes that are expressed in Arabidopsis pollen causes distinct phenotypes, implying distinct functions for various RICs. RIC3 (group III) and RIC4 (group V) both cause depolarized growth like Rop1 and display Rop1-enhanced localization to the tip of pollen tubes, suggesting that these RICs may be two distinct targets of Rop1. In contrast, RIC10 (group I) promotes pollen tube elongation but does not affect pollen tube growth polarity and shows Rop1-independent localization to the cytoplasm, suggesting that RIC10 may participate in a Rop1-independent pathway probably controlled by a different Rop. Expression of all other RICs causes various degrees of growth inhibition in pollen tubes. Furthermore, these inhibitory RICs also exhibit distinct patterns of localization in pollen tubes. Our results suggest that various RICs have evolved to interact with Rops differentially and to perform distinct functions in pollen tubes. Reverse transcriptase-mediated polymerase chain reaction analysis showed that six of the nine RICs are expressed in various parts of Arabidopsis plants. On the basis of these observations, we propose that RICs function as Rop GTPase targets that control various Rop-dependent signaling pathways in plants.

A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets

The plant-specific Rop family GTPases are versatile molecular switches in many processes during plant growth, development, and responses to the environment. To understand how Rop achieves its functional versatility in signaling, we performed a genome-wide identification of putative Rop targets using a combination of the yeast two-hybrid method, bioinformatic tools, and a robust functional assay in pollen. In this study, we have identified 11 Arabidopsis genes encoding novel proteins, termed RICs (for Rop-interactive CRIB motif-containing proteins), that contain a CRIB (for Cdc42/Rac-interactive binding) motif required for their specific interaction with GTP-bound Rop1. RICs are divergent and classified into five groups that share little sequence homology outside of the conserved Rop-interactive domain. Overexpression in tobacco pollen tubes of the nine Ric genes that are expressed in Arabidopsis pollen causes distinct phenotypes, implying distinct functions for various RICs. RIC3 (group III) and RIC4 (group V) both cause depolarized growth like Rop1 and display Rop1-enhanced localization to the tip of pollen tubes, suggesting that these RICs may be two distinct targets of Rop1. In contrast, RIC10 (group I) promotes pollen tube elongation but does not affect pollen tube growth polarity and shows Rop1-independent localization to the cytoplasm, suggesting that RIC10 may participate in a Rop1-independent pathway probably controlled by a different Rop. Expression of all other RICs causes various degrees of growth inhibition in pollen tubes. Furthermore, these inhibitory RICs also exhibit distinct patterns of localization in pollen tubes. Our results suggest that various RICs have evolved to interact with Rops differentially and to perform distinct functions in pollen tubes. Reverse transcriptase-mediated polymerase chain reaction analysis showed that six of the nine RICs are expressed in various parts of Arabidopsis plants. On the basis of these observations, we propose that RICs function as Rop GTPase targets that control various Rop-dependent signaling pathways in plants.

Suppressor of cytokine signaling-3 is a biomechanical stress-inducible gene that suppresses gp130-mediated cardiac myocyte hypertrophy and survival pathways

The gp130 cytokine receptor activates a cardiomyocyte survival pathway during the transition to heart failure following the biomechanical stress of pressure overload. Although gp130 activation is observed transiently during transverse aortic constriction (TAC), its mechanism of inactivation is largely unknown in cardiomyocytes. We show here that suppressor of cytokine signaling 3 (SOCS3), an intrinsic inhibitor of JAK, shows biphasic induction in response to TAC. The induction of SOCS3 was closely correlated with STAT3 phosphorylation, as well as the activation of an embryonic gene program, suggesting that cardiac gp130-JAK signaling is precisely controlled by this endogenous suppressor. In addition to its cytoprotective action, gp130-dependent signaling induces cardiomyocyte hypertrophy. Adenovirus-mediated gene transfer of SOCS3 to ventricular cardiomyocytes completely suppressed both hypertrophy and antiapoptotic phenotypes induced by leukemia inhibitory factor (LIF). To our knowledge, this is the first clear evidence that these two separate cardiomyocyte phenotypes induced by gp130 activation lie downstream of JAK. Three independent signaling pathways, STAT3, MEK1-ERK1/2, and AKT activation, that are coinduced by LIF stimulation were completely suppressed by SOCS3 overexpression. We conclude that SOCS3 is a mechanical stress-inducible gene in cardiac muscle cells and that it directly modulates stress-induced gp130 cytokine receptor signaling as the key molecular switch for a negative feedback circuit for both myocyte hypertrophy and survival.

Anatomic basis of vascularized ulnar nerve graft by the pedicle of the superior collateral ulnar artery

OBJECTIVE

To investigate the anatomic basis of vascularized ulnar nerve graft by the pedicle of the superior collateral ulnar artery (SCUA).

METHODS

Twenty-two fresh cadaver upper extremities injected i ntra-arterially with latex were dissected to study the extrinsic blood supply of the ulnar nerve. Other 6 fresh upper extremities were used to analyze the blood supply range of SCUA inside the ulnar nerve by microangiographic and histological methods.

RESULTS

The ulnar nerve was supplied by a branch of the lateral thoracic artery or directly by the axillary artery in the axillary section, by b ranches of SCUA in the upper arm, and by branches from the anastomosis of the collateral arteries and the posterior branch of the recurrent ulnar artery in the elbow. SCUA could supply the whole ulnar nerve from the axilla to the wrist.

CONCLUSIONS

The ulnar nerve can be used as a vascularized nerve graft by the pedicle of SCUA in treatment of brachial plexus roots avulsion by C7 transfer from healthy side.

Bringing a family practice model of health to the People's Republic of China

The health care system in the People's Republic of China (PRC) is undergoing a major transition that has made the government revise its approach to how medicine is taught and practiced. Family medicine, which provides a generalist approach to medical care, is at the forefront of this transition. This article reviews the recent history of medical education in the PRC, including the establishment of the discipline of family medicine in the mid 1980s, and factors promoting development of family medicine. These include the movement away from government-subsidized health care in hospital settings, the aging population, increased urbanization, increasing incidence of infectious diseases, and rising health care costs. We conclude from observations made in the PRC and from a review of secondary sources that family medicine in China is in its infancy. The value of understanding the role that family medicine plays within China's changing health care system is that we gain a broader perspective of the variety and growing international importance of family practice as a profession.

Mobilization of the phrenic nerve in the thoracic cavity by video-assisted thoracic surgery. Techniques and initial experience

BACKGROUND

The use of video-assisted thoracic surgery (VATS) techniques to mobilize the phrenic nerve in the thoracic cavity for neurotization after brachial plexus injury was studied.

METHODS

From August 1999 to January 2000, 10 men and 1 woman with brachial plexus injury (left side in 5 and right side in 6) joined the study group. Their ages ranged from 20 to 38 years (average, 28 years). Supine after general anesthesia, all the patients had double-lumen trachea cannulas to guarantee complete lung collapse on the operative side. Three port incisions were made to allow introduction of the following: a 10-mm Stryker endoscope through the sixth intercostal space 2 cm medial to the anterior axillary line, one instrument for manipulation in the anterior axillary line of the third intercostal space, and another in the second intercostal space about 2 cm lateral to the parasternal line. The nerve was mobilized with two common long Mixter clamps and some endoscopic instruments by blunt and sharp dissection.

RESULTS

All patients were managed successfully without severe complications. The mean additional length of phrenic nerves by this technique was 16 cm.

CONCLUSIONS

Mobilization of the phrenic nerve by VATS is a safe and minimally invasive method for elongating the nerve for neurotization after brachial plexus injury.

[Clinicopathologic features and prognosis of lymphoepithelioma-like carcinoma of the lung]

OBJECTIVE

To analyze the clinicopathologic features and prognosis of lymphoepithelioma-like carcinoma (LELC) of the lung.

METHODS

26 cases of pulmonary LELC with available long-term follow-up information were compared with 84 cases of pulmonary non-LELC(33 cases of squamous cell carcinoma, 36 cases of adenocarcinoma, 6 cases of adeno-squamous carcinoma and 9 cases of large cell carcinoma) with available long-term follow-up information using Kaplan-Meier method and the generalized Wilcoxon test.

RESULTS

LELC of the lung had a better prognosis than non-LELC (P < 0.05). Further study showed that pulmonary LELC had a significantly better prognosis than adeno-squamous carcinoma and large cell carcinoma. However, there was no significant prognostic differences between pulmonary LELC and squamous cell carcinoma and adenocarcinoma. Tumor recurrence and necrosis (> or = 5% of tumor) were associated with poor prognosis.

CONCLUSION

Pulmonary LELC, which is a very rare and unique entity, has a better prognosis after therapy.

[A comparative observation preoperatively and postoperatively of nasal mucosa in chronic sinusitis treated with endoscopic sinus surgery]

OBJECTIVES

To study morphologic and functional mucosal changes both preoperatively and postoperatively in chronic sinusitis (CS) treated with endoscopic sinus surgery (ESS).

METHODS

1. Saccharin test and light microscopic examination of nasal mucosa were taken preoperatively and postoperatively in 32 cases with CS and in 28 normal subjects as control. 2. Scanning and transmission electron microscopy were performed to exam preoperatively and postoperatively the nasal mucosa in 10 cases with CS and in 2 normal cases as control.

RESULTS

1. The preoperative saccharin test time (STT) in patients with CS was significantly longer than that in the controls (P < 0.001), and the postoperative STT became significantly shorter than that in preoperative one(P < 0.001). 2. The pathological changes of nasal mucosa, such as infiltration in inflammatory cells, edema, polypoid formations and pathologic glands were observed preoperatively. The infiltration in inflammatory cells, edema and polypoid formations were significantly released (P < 0.01) at four months after operation, and there was no significant difference comparing with the controls (P > 0.05). However, the pathologic glands were not reduced even after four months postoperatively. 3. The examination of electron microscopy demonstrated that the ultrastructure of nasal mucosa was impaired preoperatively and almost completely recovered at four months postoperatively.

CONCLUSIONS

The normal structure and clearance function of nasal mucosa in patients with CS was impaired preoperatively, and the impaired structure and mucociliary clearing function of nasal mucosa were greatly improved after ESS and almost completely recovered at four months postoperatively. The pathologic glands and secretive function of nasal mucosa may need longer period for recovering.

Fission yeast (Schizosaccharomyces pombe) cells defective in the MutY-homologous glycosylase activity have a mutator phenotype and are sensitive to hydrogen peroxide

The modified base 7,8-dihydro-8-oxo-guanine (8-oxoG) is one of the most stable deleterious products of oxidative DNA damage because it mispairs with adenine during DNA replication. In the fission yeast Schizosaccharomyces pombe, the MutY homolog (SpMYH) is responsible for removing misincorporated adenines from A/8-oxoG or A/G mismatches and thus preventing G:C to T:A mutations. In order to study the functional role of SpMYH, an SpMYH knockout strain was constructed. The SpMYH knockout strain, which does not express SpMYH and has no A/8-oxoG glycosylase activity, displays a 36-fold higher frequency of spontaneous mutations than the wild type strain. Disruption of SpMYH causes increased sensitivity to H2O2 but not to UV-irradiation. Expression of SpMYH in the mutant cells restores the adenine glycosylase activity, reduces the mutation frequency, and elevates the resistance to H2O2. Asp172 of SpMYH is conserved in a helix-hairpin-helix superfamily of glycosylases. The SpMYHA strain expressing D172N SpMYH retained the mutator phenotype. Moreover, when D172N mutant SpMYH was expressed in the wild-type cells, the mutation frequency observed was even higher than that of the parental strains. Thus, a mutant SpMYH that retains substrate-binding activity but is defective in glycosylase activity exhibits a dominant negative effect. This is the first demonstration that a MutY homolog plays an important role in protecting cells against oxidative DNA damage in eukaryotes.

Directional responses of basal optic neurons are modulated by the nucleus lentiformis mesencephali in pigeons

The nucleus lentiformis mesencephali (nLM) and the nucleus of the basal optic root (nBOR) in pigeons are both involved in optokinetic nystagmus. They are reciprocally connected and thus may interact with each other. The present study injected lidocaine into nLM and then examined the effects of nLM blockade on visual responses of nBOR neurons to target motion. The results indicate that nLM could modulate nBOR activity in two ways. First, nLM enhances visual responses of 70% of nBOR cells to motion in the preferred directions, sharpening their directional tuning. Second, nLM reduces visual responses of 13% of nBOR cells to motion in the preferred directions, broadening their directional tuning. The remaining 17% of nBOR cells are not affected by drug application. Taken together with the previous results that nBOR could modulate nLM activity (Gu et al., Neuroscience, 104 (2001) 153), it suggests that both nuclei can mutually modulate each other in generating optokinetic nystagmus.

Distinct intramembrane cleavage of the beta-amyloid precursor protein family resembling gamma-secretase-like cleavage of Notch

The intramembrane cleavage of beta-amyloid precursor protein by gamma-secretase is the final step in the generation of amyloid beta-protein. A 59- or 57-residue C-terminal fragment called CTFgamma is produced concomitantly. Putative CTFgamma generated in rat brain membrane preparations was purified and sequenced. Instead of CTFgamma, shorter 50- and 49-residue fragments were identified. In addition, we found similar C-terminal fragments of beta-amyloid precursor-like proteins 1 and 2; these were also cleaved at corresponding sites. This newly identified cleavage occurs at a site two to five residues inside the cytoplasmic membrane boundary, which is very similar to gamma-secretase-like cleavage of Notch 1.

PRL antiapoptotic effect in the rat decidua involves the PI3K/protein kinase B-mediated inhibition of caspase-3 activity

During gestation, the uterus undergoes severe changes to accommodate and protect the developing conceptus. In particular, stromal endometrial cells proliferate and differentiate to form the decidual tissue, which produces PRL. Once the conceptus begins to grow, extensive regression by apoptosis take place in the decidua coincident with the loss of the PRL receptor in this tissue. In this report we have established for the first time that PRL, acting through the long form of the PRL receptor and the PI3K pathway, exerts an antiapoptotic effect in rat decidua. We have also shown that protein kinase B phosphorylation on serine 473 as well as its nuclear translocation are stimulated by PRL in decidual cells. Moreover, we have found that caspase-3, a well known effector of apoptosis, becomes expressed and active in the rat decidua just at a time when this tissue undergoes extensive apoptosis. PRL was able to down-regulate both caspase-3 mRNA levels as well as activity. Furthermore, using a protein kinase B dominant-negative expression vector, we provide evidence that PRL inhibition of caspase-3 requires an intact protein kinase B pathway. Finally, we have also found that rat placental lactogen I and II dose-dependently inhibit caspase-3 mRNA, suggesting multiple sources of PRL in the hormonal control of rat decidual regression. In summary, the results of this study have defined an important role for decidual PRL in the normal progress of pregnancy, specifically in the regression and reorganization of the decidua.

Alteration of DNA base excision repair enzymes hMYH and hOGG1 in hydrogen peroxide resistant transformed human breast cells

BACKGROUND

Oxidative stress is a major causative agent of carcinogenesis, aging, and a number of diseases. 8-oxoG is the most stable and deleterious lesion of oxidative DNA damage. The 8-oxoG lesions can be eliminated by human repair systems consisting of three enzymes hMTH1, hOGG1, and hMYH homologous to E. coli MutT, MutM, and MutY proteins, respectively.

MATERIAL AND METHODS

Human cells (P1, P2, and P3) resistant to H(2)O(2) were derived from the non-tumorigenic human breast cell line MCF10A by sequential treatment of the cells with H(2)O(2). The protein expression levels of DNA repair enzymes were analyzed by Western blotting. The DNA binding and glycosylase activities of hMYH and hOGG1 were measured in the extracts of the H(2)O(2) resistant cells.

RESULTS

The H(2)O(2) resistant cells displayed tremendously greater anchorage-independent growth capability and higher expression of the anti-apoptotic protein BCL-2 than the parental cells. H(2)O(2) detoxification ability was elevated in P1 and P2 cells, but not in P3 cells, suggesting P3 cells might employ a different defense mechanism from P1 and P2 cells. In P3 cells, both hOGG1 and hMYH glycosylase activities were reduced but their protein levels increased. Two A/8-oxoG binding complexes were detected with cell extracts: the fast-migrating complex (bottom form) was dominated in MCF10A cells, and was greatly reduced in P3 cells. Interesting, the P3 cells showing the least amount of bottom form had the weakest hMYH glycosylase activity.

CONCLUSIONS

Our results demonstrated, for the first time, that alteration of base excision repair pathways is correlated to cell resistance to oxidative stress.

The combined effects of MRI and X-rays on ICR mouse embryos during organogenesis

The combined effects of X-rays and magnetic resonance imaging (MRI) on mouse embryos at an early stage of organogenesis were investigated. Pregnant ICR mice were irradiated on day 8 of gestation with X-rays at a dose of 1 Gy and/or MRI at 0.5 T for 1 hour. The mortality rates of the embryos or fetuses, the incidence of external malformations, the fetal body weight and the sex ratio were observed at day 18 of gestation. A significant increase in embryonic mortality was observed after exposure to either 1 Gy of X-radiation or 0.5 T MRI. However, the combined X-rays and MRI did not show a statistically significant increase in embryonic mortality compared with the control. External malformations, such as exencephaly, a cleft palate and anophthalmia, were observed in mice irradiated with X-rays and/or MRI. The incidence of each malformation in all treated groups increased with statistical significance compared with the control mice. The incidence in mice irradiated with both X-rays and MRI was lower than in mice irradiated with only X-rays. The combined effects of the combination of radiation and MRI on the external malformations might be antagonistic. There were no statistically significant differences in fetal death, fetal body weight and sex ratio among all experimental groups.