Sonic hedgehog promotes stem-cell potential of Müller glia in the mammalian retina

Müller glia have been demonstrated to display stem-cell properties after retinal damage. Here, we report this potential can be regulated by Sonic hedgehog (Shh) signaling. Shh can stimulate proliferation of Müller glia through its receptor and target gene expressed on them, furthermore, Shh-treated Müller glia are induced to dedifferentiate by expressing progenitor-specific markers, and then adopt cell fate of rod photoreceptor. Inhibition of signaling by cyclopamine inhibits proliferation and dedifferentiation. Intraocular injection of Shh promotes Müller glia activation in the photoreceptor-damaged retina, Shh also enhances neurogenic potential by producing more rhodopsin-positive photoreceptors from Müller glia-derived cells. Together, these results provide evidences that Müller glia act as potential stem cells in mammalian retina, Shh may have therapeutic effects on these cells for promoting the regeneration of retinal neurons.

Evaluating the role of connexin43 in congenital heart disease: Screening for mutations in patients with outflow tract anomalies and the analysis of knock-in mouse models

Background:

GJA1 gene encodes a gap junction protein known as connexin 43 (Cx43). Cx43 is abundantly expressed in the ventricular myocardium and in cardiac neural crest cells. Cx43 is proposed to play an important role in human congenital heart disease, as GJA1 knock-out mice die neonatally from outflow tract obstruction. In addition, patients with visceroatrial heterotaxia or hypoplastic left heart syndrome were reported to have point mutations in GJA1 at residues that affect protein kinase phosphorylation and gating of the gap junction channel. However, as these clinical findings were not replicated in subsequent studies, the question remains about the contribution of GJA1 mutations in human congenital heart disease (CHD).

Materials and Methods:

We analyzed the GJA1 coding sequence in 300 patients with CHD from two clinical centers, focusing on outflow tract anomalies. This included 152 with Tetralogy of Fallot from over 200 patients exhibiting outflow tract anomalies, as well as other structural heart defects including atrioventricular septal defects and other valvar anomalies. Our sequencing analysis revealed only two silent nucleotide substitutions in 8 patients. To further assess the possible role of Cx43 in CHD, we also generated two knock-in mouse models with point mutations at serine residues subject to protein kinase C or casein kinase phosphorylation, sites that are known to regulate gating and trafficking of Cx43, respectively.

Results:

Both heterozygous and homozygous knock-in mice were long term viable and did not exhibit overt CHD.

Conclusion:

The combined clinical and knock-in mouse mutant studies indicate GJA1 mutation is not likely a major contributor to CHD, especially those involving outflow tract anomalies.

Acute photoreceptor degeneration down-regulates melanopsin expression in adult rat retina

Melanopsin in retinal ganglion cells plays an important role in mammalian circadian systems. Previous studies indicate melanopsin is responsible for circadian photoentrainment independent of classical rods and cones. However, expression of melanopsin in ganglion cells may be regulated by photoreceptors. In this study, we investigated the effects of N-methyl-N-nitrosourea (MNU)-induced acute photoreceptor degeneration on melanopsin mRNA expression and protein distribution in adult rats. Expression of melanopsin was analyzed 0.5, 1, 5, 7, 13 and 28 days after MNU administration by real-time RT-PCR and immunohistochemistry. MNU-induced gradual degeneration of photoreceptors, and by day 7 most of the photoreceptors were lost. The number of ganglion cells did not change significantly at all time points after MNU injection. In contrast, melanopsin mRNA decreased gradually with the loss of photoreceptors, at the same time pituitary adenylate cyclase-activating polypeptide (PACAP) mRNA levels, which co-express with melanopsin in ganglion cells, were not affected by MNU treatment, indicating decrease of melanopsin mRNA levels is not due to ganglion cell damage. Distribution of melanopsin protein in the dendrites of ganglion cells dramatically decreased with the degeneration of photoreceptors, but its expression in the soma persisted for a long time. Our results suggest that intact photoreceptors maintain the expression of melanopsin and its distribution in ganglion cell dendrites.

Binding of the maize cytosolic Hsp70 to calmodulin, and identification of calmodulin-binding site in Hsp70

Using a gel-overlay technique of biotinylated calmodulin (CaM), we showed that maize cytosolic Hsp70 protein could bind to CaM in the presence of 1 mM CaCl2. The purified maize cytosolic Hsp70 inhibited the activity of CaM-dependent NADK in a concentration-dependent manner. A synthetic peptide, which possesses the 21 amino acid sequence, PRALRRLRTACERAKRTLSST, at positions 261-281 in maize cytosolic Hsp70, could associate with CaM in the presence of 1 mM calcium. The synthetic peptide inhibited CaM-dependent NADK activity and PDE activity. This indicates that the 21-amino acid sequence at positions 261-281 is the CaM-binding site. The binding of CaM to Hsp70 inhibited the ATPase activity of Hsp70. The possible regulator function of Hsp70 in cell signaling events in response to heat stress is discussed.

Antimicrobial susceptibilities and beta-lactamase production of Hong Kong isolates of gastroenteric salmonellae and Salmonella typhi

We examined the in-vitro antibiotic susceptibility of 760 gastroenteric salmonellae and 36 strains of Salmonella typhi isolated in Hong Kong between 1985 and 1988. S. typhi remained susceptible to all the antibiotics tested except for one isolate resistant to chloramphenicol, another to kanamycin and co-trimoxazole, and a third to nalidixic acid. In contrast, resistance and multiple resistance has increased significantly in gastroenteric salmonellae over the last ten years. Seventeen percent were resistant to ampicillin, 61% to tetracycline, 23% to chloramphenicol and 8% to gentamicin. Many ampicillin-resistant strains remained resistant to ampicillin even in the presence of sulbactam (69%) or clavulanic acid (25%). More than 50% of isolates were resistant to two or more antibiotics and one isolate was resistant to eleven. Ampicillin-resistance was usually due to the production of TEM-1 or OXA-1 beta-lactamases but a few isolates produced AER-1, PSE-1 or PSE-2. Genetic determinants for these enzymes were usually borne on plasmids ranging in size from 2 to 143.7 Md but half of the OXA-1 genes were chromosomally located.

Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Comparison of blood-nerve barrier disruption and matrix metalloprotease-9 expression in injured central and peripheral nerves in mice

To investigate the involvement of blood-born factors and extracellular proteases in axonal degeneration and regeneration in both PNS and CNS, we directly compared the differences of blood-nerve barrier (BNB) disruption and matrix metalloprotease-9 (MMP-9) induction between the sciatic nerve and optic nerve after crush injury in the same animal. In sciatic nerve, BNB disruption, fibrin(ogen) deposition and MMP-9 expression were observed only in the first week following injury. Neurofilament (NF) immunoreactivity dramatically decreased in the first 2 days, gradually recovered to the normal levels by day 28. In contrast, the immunoglobulin G deposits spanned from 4 h to 28 days in crushed optic nerves. Fibrin(ogen) deposition was only observed in the first 2 days, while MMP-9 induction did not occur until a week after injury but lasted for 3 weeks in the crushed optic nerves. The NF immunoreactivity did not change much until day 7 and almost completely disappeared on day 28. The decrease of NF immunoreactivity coincided with the induction of MMP-9 after optic nerve crush. These results show that BNB disruption and MMP-9 induction are differentially regulated in the PNS and CNS after injuries, and they may contribute to the different regeneration capacities of the two systems.

Orphanin FQ/nociceptin modulates glutamate- and kainic acid-induced currents in acutely isolated rat spinal dorsal horn neurons

The heptadecapeptide orphanin FQ (OFQ), also known as nociceptin (NOC), is a newly discovered endogenous ligand for the opioid-like G-protein coupled receptor, ORL1. In the present study, the effects of OFQ/NOC on glutamate (Glu), kainic acid (KA) and quisqualic acid (QA) induced currents were examined in isolated rat spinal dorsal horn neurons of young rats using whole-cell patch-clamp techniques. Glu, KA and QA elicited rapid inward currents in 90%, 69%, 83% of tested neurons. OFQ/NOC(0.03 approximately 300 nM) failed to induce any changes of membrane currents, but modulated Glu-, KA- and QA-elicited currents. OFQ/NOC inhibited and potentiated Glu-induced currents in 40.6% and 27.3% of examined cells (n=106) respectively. In about one third examined neurons, OFQ/NOC had no detectable effects on Glu responses. OFQ/NOC also inhibited and enhanced KA- and QA-induced currents (inhibition: KA, 67.1%, n=76; QA, 50%, n=36. Potentiation: KA, 23.7%, n=76; QA, 16.7%, n=36). In about 10% of tested cells, Glu-induced currents were potentiated after the application of OFQ/NOC, and lasted for 20 approximately 30 min. The inhibitory effects of OFQ/NOC on KA and QA responses were naloxone-insensitive. The C-terminal fragment OFQ(8-17) presented same effects on EAA-induced responses. Taken together, OFQ/NOC primarily inhibited Glu-, KA- and QA-induced currents in isolated rat spinal dorsal horn neurons via non-opioid mechanism, which might contribute to nociceptive transmission in the spinal level.

Transplantation of Retinal Progenitor Cells from Optic Cup-Like Structures Differentiated from Human Embryonic Stem Cells In Vitro and In Vivo Generation of Retinal Ganglion-Like Cells

Human embryonic stem cells (hESCs) have the potential to differentiate along the retinal lineage. We have efficiently differentiated human pluripotent stem cells into optic cup-like structures by using a novel retinal differentiation medium (RDM). The purpose of this study was to determine whether the retinal progenitor cells (RPCs) derived from hESCs can integrate into the host retina and differentiate into retinal ganglion cells (RGCs) in vivo. In this study, hESCs (H9-GFP) were induced to differentiate into optic cup-like structures by using our novel differentiation system. The RPCs extracted from the optic cup-like structures were transplanted into the vitreous cavity of N-methyl-d-aspartic acid-treated mice. Sham-treated eyes received the same amount of RDM. The host retinas were analyzed by triple immunofluorescence on the fourth and fifth weeks after transplantation. The optic cup-like structures were efficiently differentiated from hESCs by using our novel differentiation system in vitro for 6-8 weeks. The RPCs extracted from the optic cup-like structures migrated and integrated into the ganglion cell layer (GCL) of the host retina. Furthermore, the remaining transplanted cells were spread over the GCL and had a complementary distribution with host residual RGCs in the GCL of the mouse retina. Surprisingly, some of the transplanted cells expressed the RGC-specific marker Brn3a. These findings demonstrated that the RPCs derived from hESCs could integrate into the host GCL and differentiate into retinal ganglion-like cells in vivo, suggesting that RPCs can be used as an ideal source in supplying countless RGC and embryonic stem cell-based replacement therapies may be a promising treatment to restore vision in patients with degenerative retinal diseases.

Presynaptic inputs to vasopressin neurons in the hypothalamic supraoptic nucleus and paraventricular nucleus in mice

Arginine vasopressin (AVP) neurons in the hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) are involved in important physiological behaviors, such as controling osmotic stability and thermoregulation. However, the presynaptic input patterns governing AVP neurons have remained poorly understood due to their heterogeneity, as well as intermingling of AVP neurons with other neurons both in the SON and PVN. In the present study, we employed a retrograde modified rabies-virus system to reveal the brain areas that provide specific inputs to AVP neurons in the SON and PVN. We found that AVP neurons of the SON and PVN received similar input patterns from multiple areas of the brain, particularly massive afferent inputs from the diencephalon and other brain regions of the limbic system; however, PVN^AVP neurons received relatively broader and denser inputs compared to SON^AVP neurons. Additionally, SON^AVP neurons received more projections from the median preoptic nucleus and organum vasculosum of the lamina terminalis (a circumventricular organ), compared to PVN^AVP neurons, while PVN^AVP neurons received more afferent inputs from the bed nucleus of stria terminalis and dorsomedial nucleus of the hypothalamus, both of which are thermoregulatory nuclei, compared to those of SON^AVP neurons. In addition, both SON^AVP and PVN^AVP neurons received direct afferent projections from the bilateral suprachiasmatic nucleus, which is the master regulator of circadian rhythms and is concomitantly responsible for fluctuations in AVP levels. Taken together, our present results provide a comprehensive understanding of the specific afferent framework of AVP neurons both in the SON and PVN, and lay the foundation for further dissecting the diverse roles of SON^AVP and PVN^AVP neurons.

Alterations of immune functions induced by 12C6+ ion irradiation in mice

PURPOSE

To estimate the biological risks to the immune system of the type of space radiation, 12C6+, encountered by cosmonauts during long-term travel in space.

MATERIALS AND METHODS

The Kun-Ming strain mice were whole-body irradiated by 12C6+ ion with 0, 0.01, 0.05, 0.075, 0.2, 0.3, 0.5, 0.75, 1 or 2 Gy, at a dose rate of 1 Gy/min. At 35 days after irradiation, the thymus and spleen weights were measured, the natural killer (NK) cells activity of spleen was determined by 3-(4, 5-dimethylthiazol-2-yl)- 2, 5-diphenyl tetrazolium bromide (MTT), and the interferon-gamma (IFN-gamma) levels in serum and thymus were detected with enzyme-linked immunosorbent assays (ELISA).

RESULTS

The results showed that the thymus weight, IFN-gamma levels in serum and the activity of splenic NK-cells had significantly increased at a dose of 0.05 Gy. With further dose increase, the weight of spleen continued to increase but the weight of thymus, IFN-gamma level and NK-cells activity declined.

CONCLUSIONS

These results suggest that the dose of 0.05 Gy irradiation has a stimulatory effect on mouse immunity; this effect declined with increasing dose.

Observation of a threshold enhancement in the plambda invariant-mass spectrum

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Nuclear isoform of FGF13 regulates post-natal neurogenesis in the hippocampus through an epigenomic mechanism

The hippocampus is one of two niches in the mammalian brain with persistent neurogenesis into adulthood. The neurogenic capacity of hippocampal neural stem cells (NSCs) declines with age, but the molecular mechanisms of this process remain unknown. In this study, we find that fibroblast growth factor 13 (FGF13) is essential for the post-natal neurogenesis in mouse hippocampus, and FGF13 deficiency impairs learning and memory. In particular, we find that FGF13A, the nuclear isoform of FGF13, is involved in the maintenance of NSCs and the suppression of neuronal differentiation during post-natal hippocampal development. Furthermore, we find that FGF13A interacts with ARID1B, a unit of Brahma-associated factor chromatin remodeling complex, and suppresses the expression of neuron differentiation-associated genes through chromatin modification. Our results suggest that FGF13A is an important regulator for maintaining the self-renewal and neurogenic capacity of NSCs in post-natal hippocampus, revealing an epigenomic regulatory function of FGFs in neurogenesis.

Observation of the decay psi(2S)-->K0SK0L

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Observation of two new N* peaks in J/psi-->ppi-n and ppi+n decays

The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.

MMP-9 inhibition facilitates amacrine cell loss after ouabain-induced retinal damage

Retinal ischemia is a common risk factor for visual impairment and blindness. Two common changes after retinal ischemia are retinal ganglion cell (RGC) loss and Müller glial cell (MGC)-mediated endogenous repair. Matrix metalloproteinase 9 (MMP-9) has been shown to be responsible to RGC death. However, the effects of MMP-9 on the loss of other neurons and the reactivity of MGCs after retinal injury remain unclear. Ouabain, a Na/K-ATPase inhibitor, was injected into the vitreous body of rat eyes to induce cell death in the inner nuclear layer (INL). MMP-9 expression and activation in the retinas were examined by gelatin zymography and immunohistochemistry. The role of MMP-9 inhibitor (MMP-9i) in ouabain-treated retinas was assessed. After ouabain injection, there was an upregulation of MMP-9 activity in the inner retinas, and the activation of MMP-9 reached a maximum at 2 day. Unexpectedly, MMP-9i enhanced the thinning of the INL, the loss of Calbindin D-28k-positive cells and Syntaxin-positive amacrine cells (ACs) in the INL and decreased levels of Calbindin D-28k protein, while leaving the outer nuclear layer (ONL) unchanged. In addition, MMP-9i led to a minor increase in the number of BrdU positive cells that did not express GS in the INL. Collectively, these results revealed that the inhibition of MMP-9 activity facilitated AC loss and promoted the generation of MGC-derived cells in ouabain-treated retinas, which indicates that treating retinal diseases with drugs that inhibit MMP-9 activity should be considered with caution.

[Comparative study of decentration, tilt and visual quality after implantation of aspherical intraocular lenses]

Objective: To compare the difference of decentration and tilt among 4 kinds of aspherical intraocular lenses (IOLs), and to analyze their objective visual quality. Methods: Prospective non-randomized controlled clinical trial. Age-related cataract patients who planned to undergo phacoemulsification and IOL implantation in the Affiliated Hospital of North Sichuan Medical College from April to June in 2020 were divided into ZCB00 group, SN60WF group, A1-UV group, and AO group according to IOL types. Thirty right eyes and thirty left eyes were selected in each group. Before operation and at 1 day, 1 week and 1 month postoperatively, decentration and tilt values were measured by a new swept-source anterior-segment optical coherence tomography device (CASIA2), and wavefront aberrations, objective scatter index (OSI), modulation transfer function cut off frequency (MTF cut off) and Strehl ratio (SR) were also examined. Values of decentration, tilt and visual quality compared among 4 groups were took from the right eye. One-way analysis of variance was used for inter-group comparison, and repeated measurement one-way analysis of variance was used for intra-group comparison. Data between right eyes and left eyes from all the individuals were compared by independent sample t-test. Results: A total of 181 patients (240 eyes) were enrolled, and 169 patients (224 eyes) completed the follow-up (114 right eyes and 110 left eyes). There were 77 males and 92 females, with an age of (69±9) years. There was no significant difference in gender, age, axial length, decentration and tilt of crystalline lens and IOL power among 4 groups (all P>0.05). At 1 day, 1 week and 1 month postoperatively, there was significant difference in decentration value among 4 groups (F=7.11, 6.12, 4.66; all P<0.05). For further pairwise comparison, the decentration value of SN60WF group was higher than that of the other 3 groups at 1 day and 1 week postoperatively, and the decentration value of SN60WF group was (0.259±0.101) mm at 1 month postoperatively, which was higher than that of ZCB00 group (0.177±0.099) mm and AO group (0.163±0.122) mm, and the differences were statistically significant (using SNK-q test, both P<0.05). The IOL tilt value in the ZCB00 group, SN60WF group, A1-UV group, and AO group at 1 month postoperatively were (4.806±1.129)°, (5.080±1.309)°, (4.586±1.338)°, (5.112±1.406)°, respectively. No significant difference in tilt value among 4 groups was found at any time after surgery (all P>0.05). In each group, there was no significant difference in decentration and tilt value at different postoperative time points (all P>0.05). At 1 month postoperatively, there was no significant difference in decentration and tilt at horizontal and vertical directions respectively among 4 groups (all P>0.05), and in each group, there was no significant difference in decentration and tilt value between right eyes and left eyes (all P>0.05), and IOLs tended to tilt towards the inferonasal or inferotemporal direction in both eyes. With 4-mm and 6-mm pupil diameter, there was significant difference in internal (F=131.32, 85.17) and ocular (F=46.64, 47.55) spherical aberration among 4 groups (all P<0.01). For further pairwise comparison, the spherical aberration of AO group was higher than that of the other 3 groups, and the difference was statistically significant (using SNK-q test, all P<0.05). There was no significant difference in OSI, MTF cut off and SR among 4 groups (all P>0.05). Conclusions: The four types of IOLs show decentration and tilt in varying degrees after implantation in the capsular bag, but this difference do not lead to clinical significance. Human eyes have tolerance to mild decentration and tilt of aspheric IOLs, showing good visual quality.

Endothelin-1 promoted proliferation of vascular smooth muscle cell through pathway of extracellular signal-regulated kinase and cyclin D1

AIM

To investigate whether endothelin-1 (ET-1) can promote human umbilical artery smooth muscle cell (HUASMC) proliferation through pathway of extracellular signal-regulated kinase (ERK) and cyclin D1.

METHODS

The effects of ET-1 and PD98059 on HUASMC were evaluated by MTT assay. The content of DNA was defined by [3H]TdR assay and cell cycle was analyzed by flow cytomerty. Western blot analysis was employed to detect the active phosphorylated state of ERK and the expression of cylin D1.

RESULTS

Firstly, ET-1 (100 nmol/L) stimulated HUASMC proliferation compared with the group without ET-1 (P<0.05) and PD98059 group (P<0.05). PD98059 inhibited the HUASMC proliferation stimulated by ET-1 (P<0.05). Secondly, ET-1 stimulated DNA synthesis of HUASMC compared with the group without ET-1 (P<0.05). Thirdly, ET-1 promoted the cell cycle transition from G0/G1 phase to S phase. G0/G1 phase cell percentage was obviously decreased compared with the group without ET-1 (P<0.05). S phase cell percentage was increased compared with the group without ET-1 (P<0.05). Fourthly, ET-1 increased the phosphorylated level of ERK and the expression of cylin D1, an inhibitor of ERK blocked phosphorylated level of ERK and cyclin D1 expression. ERK phosphorylated level of ET-1 group was evidently increased compared with PD98059 group (P<0.05), Cyclin D1 protein expression also was increased compared with PD98059 group (P<0.05). While nonphosphorylated ERK expression remained unchanged.

CONCLUSION

Endothelin-1 promoted vascular smooth muscle cell proliferation through pathway of ERK and cyclin D1.

[Spatio-temporal expression of connexion (Cx) 40 and Cx45 in Cx43 knockout embryonic mouse hearts]

OBJECTIVE

To investigate the spatio-temporal expression of connexin (Cx) 40 and Cx45 genes in Cx43 knockout embryonic mouse hearts.

METHODS

Cx43 knockout heterozygous mice were raised. PCR was performed to identify genotypes of their offsprings. The homozygote (Cx43-/-) was used for study and the wild type (Cx43+/+) was used as control. Immuno-histochemistry was used to detect the Cx40 and Cx45 expression in different parts of the fetal hearts at the embryonic days (EDs) 10.5, 11.5, 12.5, 13.5, 14.5, and 15.5, respectively. SCIM microscopic image analytic system was used for quantitative analysis of staining intensity.

RESULTS

(1) Cx40 expression was detected in ventricles of Cx43+/+ fetal heart as early as ED10.5 with the intensity represented by A value of 8.6. Subsequently it was distributed in the atria and ventricles with the peak expression observed at ED14.5 (A value = 94.8), and faded afterwards. Less Cx40 expression was observed in the Cx43-/- fetal hearts as compared with Cx43+/+ although its expression pattern was similar in both groups. (2) Cx45 expression was detected in ventricles at ED 10.5 (A value = 20.0). It was subsequently distributed in the atria and ventricles with the peak expression observed at ED12.5 (A value = 49.6), and then faded. Less Cx45 expression was observed in the Cx43-/- fetal hearts as compared with Cx43+/+ although its expression pattern was similar as well in both groups.

CONCLUSION

Down-regulated expression of the genes Cx40 and Cx45 may be associated with the abnormal heart development in Cx43 knockout animals.

The impact of different gastrointestinal reconstruction techniques on gut microbiota after gastric cancer surgery

Introduction

Gastric cancer is one of the common malignant tumors in the digestive tract, characterized by high incidence and mortality rates. This is particularly significant in China, where a large proportion of global new cases of gastric cancer and related deaths occur. In recent years, with the continuous development of molecular biology technology, people have gained a deeper understanding of the gastrointestinal microbiome, and studies have shown that it is closely related to the occurrence, development, and therapeutic response of gastric cancer. Although surgical intervention is crucial in significantly extending the survival of gastric cancer patients, the disruption of the balance of the intestinal microbiota caused by surgery itself should not be overlooked, as it may affect postoperative recovery.

Methods

This study was approved by the Biomedical Ethics Committee of Sichuan Mianyang 404 Hospital. A random sampling method was used to select patients who underwent gastric cancer surgery at the hospital from January 2023 to December 2023. All patients signed written informed consent forms. Standardized perioperative management was conducted for the patients in the study, including preoperative preparation, intraoperative handling, and postoperative treatment. Fecal samples were collected from patients before surgery (before bowel preparation) and around one week after surgery for 16S rRNA sequencing analysis, through which differential biomarkers and related functional genes were sought.

Results

The study results indicated that there was no significant difference in the diversity of the gut microbiota between the two groups. Compared with the R-Y group, the DTR surgical method significantly altered the structure of the gut microbiota, affecting the types, quantities, and proportions of intestinal bacteria. Furthermore, the DTR group exhibited poorer postoperative nutritional absorption capacity compared to the R-Y group, as indicated by a lower F/B ratio. The R-Y group showed a richer abundance of Bacteroidetes and a lower abundance of Proteobacteria, as well as a higher F/B ratio after surgery. These findings provide new insights into the changes in the gut microbiota following gastric cancer surgery, which may be of significant importance for postoperative recovery and long-term health management.

Discussion

This study reveals the impact of different gastrointestinal reconstruction techniques on the postoperative gut microbiota of gastric cancer patients, providing new insights into the physiological changes during the postoperative recovery period. Although there was no significant difference in microbial diversity between the DTR group and the R-Y group, the DTR group showed more pronounced changes in microbial structure postoperatively, which may be associated with an increased risk of postoperative infection. These findings emphasize the importance of considering the impact on the gut microbiota when selecting gastric cancer surgery methods. However, the study had a limited sample size and did not delve into changes in metabolites. Future studies should expand the sample size and conduct metabolomic analyses to further validate these preliminary findings.

[Effects of different oxygen inhalation modes on retinal vessels development in neonatal mice]

OBJECTIVE

This study was designed to investigate the effects of different oxygen inhalation modes on retinal vessels development in neonatal mice in order to provide experimental data for proper oxygen therapy for premature infants.

METHODS

A total of 144 postnatal day (P) 7 C57BL/6J mice were randomly assigned into 6 groups according to different oxygen inhalation modes (n=24). Experimental group 1 was exposed to 30%, 40%, 50%, 60% and 75% oxygen in turn for one day respectively, followed by room air exposure for 5 days. Experimental group 2 was exposed to 75%, 60%, 50%, 40% and 30% oxygen in turn for one day respectively, followed by room air exposure for 5 days. Experimental group 3 was exposed to 75% oxygen for 5 days, followed by room air exposure for 5 days. Experimental group 4 was exposed to 75% oxygen for 5 days, 50% oxygen for 2 days and 30% oxygen for 2 days, then room air exposure for 6 days. The supplemental 75% oxygen and room air recovering was performed alternately for the mice in Experimental group 5 for 3 times and then room air exposure for 5 days. The Control group was exposed to room air for consecutive 10 days. The retinal vascular development and proliferation were evaluated by the retinal flat-mounts (ADPase stained retina) and cross-section.

RESULTS

The peripheral vascular pattern was clear, and a few avascular areas were seen in the Control group at P12. At P14 the avascular area disappeared. At P17, the entire vascular pattern became completely normal. In the Experimental groups 1, 3 and 5, the central vessels became tortuous and constricted and the central avascular area increased at P12. At P14, neovascularization was seen peaking at P17 in the Experimental groups 1, 3 and 5. In the Experimental group 4, the central avascular area increased and neovascularization was seen at P14, but the central avascular area was reduced and abnormal neovascularization disappeared, with slight constriction of the deep vessels, at P17. Five days later the vascular pattern became almost normal in the Experimental group 4. The retinal vascular form of the Experimental group 2 was similar to that of the Control group. The average number of neovascular nuclei extending into the vitreous per cross-section in the Experimental groups 1, 2, 3, 4, and 5 and the Control group was 49.50 +/- 1.36, 5.17 +/- 0.67, 47.68 +/- 4.70, 5.74 +/- 2.37, 29.15 +/- 2.48, and 1.22 +/- 0.20 respectively. There were significant differences between the Experimental groups 1, 3, 5 and the Control group (P < 0.05).

CONCLUSIONS

The effects of different oxygen inhalation modes on the retinal vessels development in neonatal mice were different. The obvious fluctuation of inhaled oxygen concentration and abrupt stop of supplemental oxygen after high levels of supplemental oxygen may severely affect the development of retina vascular, leading to the pathologic changes similar to retinopathy of prematurity.