Condensation of carbon in radioactive supernova gas

Chemistry resulting in the formation of large carbon-bearing molecules and dust in the interior of an expanding supernova was explored, and the equations governing their abundances were solved numerically. Carbon dust condenses from initially gaseous carbon and oxygen atoms because energetic electrons produced by radioactivity in the supernova cause dissociation of the carbon monoxide molecules, which would otherwise form and limit the supply of carbon atoms. The resulting free carbon atoms enable carbon dust to grow faster by carbon association than the rate at which the dust can be destroyed by oxidation. The origin of presolar micrometer-sized carbon solids that are found in meteorites is thereby altered.

Influence of foot, leg and shoe characteristics on subjective comfort

The purpose of this study was to determine the relationships between foot and leg characteristics, shoe characteristics, and the short-term subjective comfort of three different pairs of athletic shoes. Static measurements of foot dimension and leg angles were taken from eighteen subjects. Subjects rated the comfort of three different athletic shoes for standing, walking and running. The shoes were quantified by internal dimensions, hardness, flexibility and torsional stiffness. Average comfort ratings decreased from standing to walking to running. One shoe seemed suited for only a small group of subjects. In contrast, another shoe was generally comfortable for a large group. Skeletal alignment, specifically eversion angle, was related to comfort for one shoe. Therefore, fit of the shoe is not sufficient for comfort. Skeletal alignment, shoe torsional stiffness and cushioning seem to be mechanical variables which may be important for comfort.

Persistent genetic abnormalities in Barrett's esophagus after photodynamic therapy

BACKGROUND & AIMS

Photodynamic therapy (PDT) is a technique for nonsurgical treatment of patients with dysplasia in Barrett's esophagus. The primary endpoint for PDT has been resolution of dysplasia. We studied the effect of PDT at the genetic level.

METHODS

Archival material from 3 patients who had initial improvement in dysplasia after PDT but occurrence of high-grade dysplasia during follow-up was used. Biopsy specimens were analyzed for increased proliferation, aneuploidy, p53 protein overexpression, p53 mutations, and p16 promoter hypermethylation.

RESULTS

Patients developed high-grade dysplasia 16, 28, and 37 months after PDT. In all cases, one or more genetic markers were positive after PDT treatment, whereas histology was downstaged consistently after therapy. Increasing genetic abnormalities were noted by the end of follow-up.

CONCLUSIONS

Genetic abnormalities may persist after PDT despite phenotypical improvement of dysplasia. These patients may progress to high-grade dysplasia or develop adenocarcinoma. Histologic improvement in dysplasia is an inadequate endpoint for PDT in patients with Barrett's esophagus.

L-n-acetyl-cysteine protection against cisplatin-induced auditory neuronal and hair cell toxicity

OBJECTIVES

The aim of this study is to determine the efficacy of L-N-acetyl-cysteine (L-NAC) as a protectant for inner ear auditory sensory cells against the toxic effects of cisplatin.

STUDY DESIGN

Prospective laboratory study of the otoprotective effect of L-NAC on auditory neurons and hair cells in vitro.

METHODS

The study has two arms. The first arm evaluated the neuroprotective effect of L-NAC on early postpartum auditory ganglion cell cultures. Two culture media were used. The two media differed in that one of them was enhanced by the addition of neurotrophins (neurotrophin type 3 and brain-derived neurotrophic factor) and a growth factor (transforming growth factor-beta1). Then the survival of cisplatin-treated auditory neurons was studied before and after pretreatment with protective levels of L-NAC. The second arm of the study evaluated the effect of L-NAC on cisplatin damage initiated to auditory hair cells. Early-postpartum organ of Corti explants were grown in culture. Their rate of survival was studied after exposure to toxic levels of cisplatin. Then, survival of cisplatin-damaged hair cells was studied after they were pretreated with L-NAC.

RESULTS

Pretreatment of cultures with L-NAC protected both auditory neurons and hair cells from the effects of exposure to toxic levels of cisplatin. This observed otoprotective effect was dose dependent.

CONCLUSIONS

Our in vitro studies have demonstrated that L-NAC protected both auditory neurons and hair cells from the toxic effects of cisplatin. Because it protects both of these inner ear structures, L-NAC may be potentially useful in protecting hearing, in general, from cisplatin-induced damage. In addition, L-NAC has low systemic and mucosal toxicity. It also has a low molecular weight that may allow it to readily cross the round window membrane. All these characteristics make it potentially suitable for transtympanic application for the prevention of the ototoxicity of cisplatin in vivo.

[Analysis of clinical features of 29 patients with 2019 novel coronavirus pneumonia]

Objective: To analyze the clinical characteristics of 2019 novel coronavirus (2019-nCoV) pneumonia and to investigate the correlation between serum inflammatory cytokines and severity of the disease. Methods: 29 patients with 2019-ncov admitted to the isolation ward of Tongji hospital affiliated to Tongji medical college of Huazhong University of Science and Technology in January 2020 were selected as the study subjects. Clinical data were collected and the general information, clinical symptoms, blood test and CT imaging characteristics were analyzed. According to the relevant diagnostic criteria, the patients were divided into three groups: mild (15 cases), severe (9 cases) and critical (5 cases). The expression levels of inflammatory cytokines and other markers in the serum of each group were detected, and the changes of these indicators of the three groups were compared and analyzed, as well as their relationship with the clinical classification of the disease. Results: (1) The main symptoms of 2019-nCoV pneumonia was fever (28/29) with or without respiratory and other systemic symptoms. Two patients died with underlying disease and co-bacterial infection, respectively. (2) The blood test of the patients showed normal or decreased white blood cell count (23/29), decreased lymphocyte count (20/29), increased hypersensitive C reactive protein (hs-CRP) (27/29), and normal procalcitonin. In most patients,serum lactate dehydrogenase (LDH) was significantly increased (20/29), while albumin was decreased(15/29). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (Tbil), serum creatinine (Scr) and other items showed no significant changes. (3) CT findings of typical cases were single or multiple patchy ground glass shadows accompanied by septal thickening. When the disease progresses, the lesion increases and the scope expands, and the ground glass shadow coexists with the solid shadow or the stripe shadow. (4) There were statistically significant differences in the expression levels of interleukin-2 receptor (IL-2R) and IL-6 in the serum of the three groups (P<0.05), among which the critical group was higher than the severe group and the severe group was higher than the mildgroup. However, there were no statistically significant differences in serum levels of tumor necrosis factor-alpha (TNF-α), IL-1, IL-8, IL-10, hs-CRP, lymphocyte count and LDH among the three groups (P>0.05). Conclusion: The clinical characteristics of 2019-nCoV pneumonia are similar to those of common viral pneumonia. High resolution CT is of great value in the differential diagnosis of this disease. The increased expression of IL-2R and IL-6 in serum is expected to predict the severity of the 2019-nCoV pneumonia and the prognosis of patients.

Cloning, expression, and characterization of a human inosine triphosphate pyrophosphatase encoded by the itpa gene

ITP and dITP exist in all cells. dITP is potentially mutagenic, and the levels of these nucleotides are controlled by inosine triphosphate pyrophosphatase (EC ). Here we report the cloning, expression, and characterization of a 21.5-kDa human inosine triphosphate pyrophosphatase (hITPase), an enzyme whose activity has been reported in many animal tissues and studied in populations but whose protein sequence has not been determined before. At the optimal pH of 10.0, recombinant hITPase hydrolyzed ITP, dITP, and xanthosine 5'-triphosphate to their respective monophosphates whereas activity with other nucleoside triphosphates was low. K(m) values for ITP, dITP, and xanthosine 5'-triphosphate were 0.51, 0.31, and 0.57 mm, respectively, and k(cat) values were 580, 360, and 640 s(-1), respectively. A divalent cation was absolutely required for activity. The gene encoding the hITPase cDNA sequence was localized by radiation hybrid mapping to chromosome 20p in the interval D20S113-D20S97, the same interval in which the ITPA inosine triphosphatase gene was previously localized. A BLAST search revealed the existence of many similar sequences in organisms ranging from bacteria to mammals. The function of this ubiquitous protein family is proposed to be the elimination of minor potentially mutagenic or clastogenic purine nucleoside triphosphates from the cell.

Molecular pieces to the puzzle of the interaction between potassium and sodium uptake in plants

Potassium uptake is vital for plant growth but in saline soils sodium competes with potassium for uptake across the plasma membrane of plant cells. This can result in high Na+:K+ ratios that reduce plant growth and eventually become toxic. Our understanding of the molecular basis underlying the interaction between essential potassium and toxic sodium was limited until the recent cloning and electrophysiological characterization of several genes encoding different types of molecules that are involved in K+ and Na+ transport. These molecules, and their regulation, are important in determining the K+:Na+ homeostasis of plants in saline soils, although it is not yet known which is most critical in determining the K+:Na+ ratios in whole plants.

Human damage-specific DNA-binding protein p48. Characterization of XPE mutations and regulation following UV irradiation

Damage-specific DNA binding (DDB) activity purifies from HeLa cells as a heterodimer (p127 and p48) and is absent from cells of a subset (Ddb(-)) of xeroderma pigmentosum Group E (XPE) patients. Each subunit was overexpressed in insect cells and purified. Both must be present for the damaged DNA band shift characteristic of the HeLa heterodimer. However, overexpressed p48 peptides containing the mutations found in three Ddb(-) XPE strains are inactive, and wild type p48 restores DDB activity to extracts from a fourth XPE Ddb(-) strain, GM01389, in which compound heterozygous mutations in DDB2 (p48) lead to a L350P change from one allele and a Asn-349 deletion from the other. Although these results indicate that these mutations are each responsible for the loss of DDB activity, they do not affect nuclear localization of p48. In normal fibroblasts, a 4-fold increase in p48 mRNA amount was observed 38 h after UV irradiation, preceding a similar elevation in p48 protein and DDB activity at 48 h, implying that p48 limits DDB activity in vivo. Because DNA repair is virtually complete before 48 h, a role for DDB other than DNA repair is suggested.

Pacing-induced heart failure causes a reduction of delayed rectifier potassium currents along with decreases in calcium and transient outward currents in rabbit ventricle

OBJECTIVE

Heart failure in patients and in animal models is associated with action potential prolongation of the ventricular myocytes. Changes in several membrane currents have been already demonstrated to underlie this prolongation. However, information on the two components (I(Kr) and I(Ks)) of the delayed rectifier potassium current (I(K)) in rapid pacing induced heart failure is lacking.

METHODS AND RESULTS

Action potentials and whole-cell currents, I(K), I(to1), I(K1), and I(Ca-L) were recorded in apical myocytes of left ventricle from 10 rabbits subjected to left ventricular pacing at 350-380 beats/min for 3-4 weeks and 10 controls with sham operation. Action potential duration at 90% repolarization (APD(90)) was prolonged in myocytes from failing hearts compared to controls at both cycle lengths of 333 and 1000 ms. Both E-4031-sensitive and -resistant components of I(K) (I(Kr), I(Ks)) in myocytes from failing hearts were significantly less than those of control hearts; tail current densities of I(Kr) and I(Ks) following depolarization to +50 mV were 0.62+/-0.05 vs. 0.96+/-0.12 pA/pF (P<0.05), and 0.27+/-0.08 vs. 0.52+/-0.08 pA/pF (P<0.05), respectively. There was no significant difference between control and failing myocytes in the voltage- and time-dependence of activation of total I(K), I(Kr) and I(Ks). The peak of L-type Ca(2+) current (I(Ca-L)) was significantly reduced in myocytes from failing hearts (at +10 mV, -9.29+/-0.52 vs. -12.28+/-1.63 pA/pF, P<0.05), as was the Ca(2+)-independent transient outward current (I(to1); at +40 mV, 4.8+/-0.9 vs. 9.6+/-1.3 pA/pF, P<0.05). Steady state I-V curve for I(K1) was similar in myocytes from failing and control hearts.

CONCLUSIONS

Decrease of I(K) (both I(Kr) and I(Ks)) in addition to reduced I(to1), may underly action potential prolongation at physiological cycle length and thereby contribute to arrhythmogenesis in heart failure.

Internal architecture of the thoracic pedicle. An anatomic study

STUDY DESIGN

In this study, data are presented that provide the surgeon with additional information about the internal structure of the thoracic pedicle, which is especially useful for pedicle screw fixation in the thoracic spine.

OBJECTIVES

To quantify the internal structure of the pedicle in the thoracic spine.

SUMMARY OF BACKGROUND DATA

There are many studies describing the external dimensions of the thoracic pedicle (i.e., pedicle height, pedicle width, and pedicle axis in the transverse and sagittal planes). However, there is little reliable information concerning the internal structure of the pedicle.

METHODS

Eighteen thoracic vertebrae were attached to a thin-sectioning machine and both pedicles were cut in six 1.0-mm thin slices. Slides of contact radiographs were rear-projected to a digitizer and the internal and external borders of the pedicle were digitized. Using special computer software, two external dimensions (i.e., pedicle height and pedicle width) and four internal dimensions (i.e., cortical thicknesses of the superior, inferior, medial, and lateral walls) were calculated.

RESULTS

The cancellous core was more than twice as large as the cortical shell, with a range from 65.6% to 78.6% with respect to the pedicle height, and 61.3% to 71.6% with respect to the pedicle width. The medial wall was between two and three times thicker than the lateral wall throughout all the pedicle slices and thoracic levels. These differences were highly significant (P < 0.001).

CONCLUSIONS

The thoracic pedicle is a complex three-dimensional structure that is mostly filled with cancellous bone. The medial wall is significantly thicker than the lateral wall, which could explain the fact that most of the pedicle fractures related to pedicle screw insertion occur laterally.

Heterogeneous distribution of the two components of delayed rectifier K+ current: a potential mechanism of the proarrhythmic effects of methanesulfonanilideclass III agents

OBJECTIVE

To elucidate the regional difference of the K+ current blocking effects of methanesulfonanilide class III agents.

METHODS

Regional differences in action potential duration (APD) and E-4031-sensitive component (IKr) as well as -insensitive component (IKs) of the delayed rectifier K+ current (IK) were investigated in enzymatically isolated myocytes from apical and basal regions of the rabbit left ventricle using the whole-cell clamp technique.

RESULTS

At 1 Hz stimulation, APD was significantly longer in the apex than in the base (223.1 +/- 10.6 vs. 182.7 +/- 14.5 ms, p < 0.05); application of 1 microM E-4031 caused more significant APD prolongation in the apex than in the base (32.5 +/- 6.4% vs. 21.0 +/- 8.8%, p < 0.05), resulting in an augmentation of regional dispersion of APD. In response to a 3-s depolarization pulse to +40 mV from a holding potential of -50 mV, both IK tail and IKs tail densities were significantly smaller in apical than in basal myocytes (IK: 1.56 +/- 0.13 vs. 2.09 +/- 0.21 pA/pF, p < 0.05; IKs: 0.40 +/- 0.15 vs. 1.43 +/- 0.23, p < 0.01), whereas IKr tail density was significantly greater in the apex than in the base (1.15 +/- 0.13 vs. 0.66 +/- 0.11 pA/pF, p < 0.01). The ratio of IKs/IKr for the tail current in the apex was significantly smaller than that in the base (0.51 +/- 0.21 vs. 3.09 +/- 0.89; p < 0.05). No statistical difference was observed in the voltage dependence as well as activation and deactivation kinetics of IKr and IKs between the apex and base. Isoproterenol (1 microM) increased the time-dependent outward current of IKs by 111 +/- 8% during the 3-s depolarizing step at +40 mV and its tail current by 120 +/- 9% on repolarization to the holding potential of -50 mV, whereas it did not affect IKr.

CONCLUSIONS

The regional differences in IK, in particular differences in its two components may underlie the regional disparity in APD, and that methanesulfonanilide class III antiarrhythmic agents such as E-4031 may cause a greater spatial inhomogeneity of ventricular repolarization, leading to re-entrant arrhythmias.

The role of the haematopoietic tissue in haemocyte production and maturation in the black tiger shrimp (Penaeus monodon)

The haematopoietic tissue (HPT) of the black tiger shrimp (Penaeus monodon) is located in different areas in the cephalothorax, mainly at the dorsal side of the stomach and in the onset of the maxillipeds and, to a lesser extent, towards the antennal gland. In young and in experimentally stimulated animals, the HPT is expanded in relatively larger and more numerous lobules throughout the cephalothorax. Four cell types could be identified in the HPT by electron microscopy. The type 1 cells are the presumed precursor cells that give rise to a large- and a small-granular young haemocyte, denominated as the type 2 and type 3 cells, respectively. A gradient of maturation from the type 1 towards the type 2 or 3 cells could frequently be observed. The presumed precursor cells are located towards the exterior of the lobules and maturing young haemocytes towards the inner part, where they can be released into the haemal lacunae. The type 4 cells show typical features of interstitial cells. Different stimulation experiments were carried out and various techniques were used to study the HPT in relation to the (circulating) haemocytes. The majority of the cells in the HPT are able to proliferate and proliferation can be increased significantly after the injection of saline and, to a much higher extent, after LPS injection. The circulating haemocytes of crustaceans are generally divided into hyaline (H), semigranular (SG) or granular (G) cells, of which large- and small-granular variants of each of these were suggested in the present study. Even after stimulation in this study, the circulating haemocytes scarcely divide. The high variations that were found in the total haemocyte count in the stimulation experiments were not accompanied by significant differences in differential haemocyte count and, therefore, appeared to be a less useful indicator of stress or health in P. monodon. Light and electron microscopical observations support the regulation of the populations of the different haemocyte types in the circulation by (stored) haemocytes from the connective tissue. In conclusion, according to morphological and immuno-chemical criteria, it is proposed in the present study to divide the haemocytes into a large-and a small-granular developmental series. After extensive morphological observations, it is suggested that the hyaline cells are the young and immature haemocytes of both the large- and small-granular cell line that are produced in the HPT, and can be released into the haemolymph. Indications were found that the granular cells, of at least the large-granular cell line, mature and accumulate in the connective tissue and are easily released into the haemolymph. Combining the results of the present study with literature, this proposed model for haemocyte proliferation, maturation and reaction will be discussed.

4-hydroxynonenal triggers an epidermal growth factor receptor-linked signal pathway for growth inhibition

Lipid peroxidation has been implicated in the pathogenesis of various diseases. As a major product of membrane lipid peroxidation, 4-hydroxynonenal (HNE) appears after various kinds of oxidative stress, and is known to induce cell growth inhibition. We here analysed the HNE-mediated signal transduction cascade for the growth inhibition of human epidermoid carcinoma A431 cells. HNE dose-dependently induced phosphorylation of multiple cellular proteins including epidermal growth factor receptor (EGFR) in A431 cells, and rapidly upregulated the catalytic actions of EGFR for autophosphorylation and for phosphorylation of casein as an exogenous substrate. Immunoblot analysis by use of HNE-specific antibody demonstrated the binding of HNE to EGFR along with its activation. This binding, which did not induce cross-linking of EGFR, caused a capping of the receptor on the cell surface which mimicked the capping induced by EGF. Phosphorylation and activation of EGFR were followed by phosphorylation of adaptor protein Shc and activation of MAP kinase. Both genistein as a wide spectrum protein tyrosine kinase inhibitor and AG1478 as a specific EGFR tyrosine phosphorylation blocker inhibited activation of EGFR and MAP kinase by HNE. The same inhibitors prevented HNE-mediated growth inhibition, suggesting a close linkage between EGFR/MAP kinase activation and growth inhibition after exposure to HNE. Our results suggest that EGFR may be one of the primary targets of HNE for an oxidative stress-linked cell growth inhibition.

Urethral seam formation and hypospadias

Knowledge of the formation of the normal male urethra may elucidate the etiology of hypospadias. We describe urethral formation in the mouse, show the similarities and relevance to human urethral development, and introduce the concept of the epithelial seam formation and remodeling during urethral formation. Three mechanisms may account for epithelial seam formation: (1) epithelial-mesenchymal transformation similar to that described in the fusion of the palatal shelves, (2) apoptosis, and/or (3) tissue remodeling via cellular migration. Urethral development in the embryonic mouse (14-21 days of gestation) was compared with urethral formation in embryonic human specimens (8-16 weeks of gestation) by using histology, immunohistochemistry, and three-dimensional reconstruction. The urethra forms by fusion of the epithelial edges of the urethral folds, giving a midline epithelial seam. The epithelial seam is remodeled via cellular migration into a centrally located urethra and ventrally displaced remnant of epithelial cells. The epithelial seam is remodeled by narrowing approximately at its midpoint, with subsequent epithelial migration into the urethra or penile skin. The epithelial cells are replaced by mesenchymal cells. This remodeling seam displays a narrow band (approximately 30 microns wide) of apoptotic activity corresponding to the mesenchymal cells and not to epithelial cells. No evidence was seen of the co-expression of cytokeratin and mesenchymal markers (actin or vimentin). Urethral seam formation occurs in both the mouse and the human. Our data in the mouse support the hypothesis that seam transformation occurs via cellular migration and not by epithelial mesenchymal transformation or epithelial apoptosis. We postulate that disruption of epithelial fusion remodeling, and cellular migration leads to hypospadias.

Localization and regulation of low affinity nerve growth factor receptor expression in the rat olfactory system during development and regeneration

Nerve growth factor (NGF), a classic neurotrophic factor, promotes neuronal survival, maintenance, regeneration and differentiation in the peripheral nervous system and parts of the central nervous system. NGF activity is mediated by cell surface bound receptors including the low affinity NGF receptor (LNGFr) which is expressed by some peripheral and central neurons and is present on peripheral nerve Schwann cells during development and regeneration. The olfactory system is a useful model for the study of the role of LNGFr in neuronal development and regeneration. The growth of olfactory axons into the brain begins in the embryo and continues through the first few postnatal weeks. In mature animals there is persistent turnover and generation of olfactory receptor neurons (ORNs) and continuous growth of new axons into the olfactory bulb. These new axons grow along the preexisting olfactory pathway. In the mature olfactory system, LNGFr has been observed in the glomerular layer of the olfactory bulb, the target of ORNs. However, neither the cellular localization nor the developmental expression of LNGFr has been characterized. Here, we tested the hypothesis that LNGFr expression is developmentally regulated in the olfactory nerve and is reinduced following injury to the mature olfactory nerve. LNGFr-immunoreactivity (IR) was first observed in the olfactory mucosa at embryonic day (E)13 and in the olfactory nerve at E14. LNGFr-IR increased in the nerve during embryonic development, began to decrease at around postnatal day (P)5 and was scarcely detectable in normal adults. The staining pattern suggests that LNGFr is located on the olfactory nerve Schwann cells. Streaks of LNGFr-IR were present in the adult olfactory nerve. We reasoned that these streaks might represent transient reexpression of LNGFr associated with normal olfactory neuron turnover and replacement. Consistent with this hypothesis, LNGFr was robustly reexpressed in the adult olfactory nerve following lesion of the olfactory epithelium. Starting late in development (E21) and in the adult, LNGFr-IR was also observed on fibers in deep layers of the olfactory bulb. LNGFr-IR was also observed in neurons of the nucleus of the diagonal band (NDB) in the basal forebrain. NDB is the sole source of cholinergic afferents of the olfactory bulb. Thus, we tested the hypothesis that LNGFr in the deep layers of the olfactory bulb is located on NDB axons by making lesions of NDB. Following the lesion, LNGFr-IR disappeared in the deep layers of the olfactory bulb but remained in the glomerular layer.(ABSTRACT TRUNCATED AT 400 WORDS)

Killed but metabolically active microbes: a new vaccine paradigm for eliciting effector T-cell responses and protective immunity

We developed a new class of vaccines, based on killed but metabolically active (KBMA) bacteria, that simultaneously takes advantage of the potency of live vaccines and the safety of killed vaccines. We removed genes required for nucleotide excision repair (uvrAB), rendering microbial-based vaccines exquisitely sensitive to photochemical inactivation with psoralen and long-wavelength ultraviolet light. Colony formation of the nucleotide excision repair mutants was blocked by infrequent, randomly distributed psoralen crosslinks, but the bacterial population was able to express its genes, synthesize and secrete proteins. Using the intracellular pathogen Listeria monocytogenes as a model platform, recombinant psoralen-inactivated Lm DeltauvrAB vaccines induced potent CD4(+) and CD8(+) T-cell responses and protected mice against virus challenge in an infectious disease model and provided therapeutic benefit in a mouse cancer model. Microbial KBMA vaccines used either as a recombinant vaccine platform or as a modified form of the pathogen itself may have broad use for the treatment of infectious disease and cancer.

I(f) current and spontaneous activity in mouse embryonic ventricular myocytes

Knowledge of the initiation of electrical and contractile activity in the embryonic heart relies to a large extent on data obtained in chicken. In recent years, molecular biological techniques have raised an interest in mouse physiology, including early embryonic development. We studied action potentials and the occurrence of one of the pacemaker currents, I(f), by the whole-cell voltage and current-clamp technique at the earliest stage at which a regular heartbeat is established (9.5 days postcoitum) and at 1 day before birth. We show, first, that at the early stage there is a prominent I(f) in mouse embryonic ventricles, which decreases by 82% before birth in concert with the loss of regular spontaneous activity of ventricular cells. Second, the decrease in I(f) current is associated with a slight change in channel gating kinetics and a decrease in total mRNA expression of the genes encoding for I(f) current. Third, the most prevalent mRNA subtype is switched from HCN4 to HCN2 during the second half of embryonic development. Fourth, the I(f) current may be modulated by the beta-adrenergic cascade, although the coupling to the beta-adrenoceptor in the sarcolemma itself is not yet mature. We conclude that I(f) current of the sinus node type is present in early embryonic mouse ventricular cells. In association with a loss of I(f) current, the ventricle tends to lose pacemaker potency during the second half of embryonic development.

Identification of the histidyl residue obligatory for the catalytic activity of the human H+/peptide cotransporters PEPT1 and PEPT2

Histidyl residues are known to be essential for the catalytic function of the H(+)-coupled peptide transporters expressed in the intestine and the kidney, most likely participating in the binding and translocation of H+. Three histidyl residues are conserved among the intestinal and renal peptide transporters (PEPT1 and PEPT2, respectively) from different animal species. In hPEPT1, these residues are His-57, His-121, and His-260. The corresponding residues in hPEPT2 are His-87, His-142, and His-278. We have individually mutated each of these histidyl residues in hPEPT1 and in hPEPT2 and compared the catalytic function of the mutants with that of their respective wild type transporters by expressing the transporters in Xenopus laevis oocytes and also in HeLa cells. His-57 in hPEPT1 and His-87 in hPEPT2 were found to be absolutely essential for catalytic activity because the corresponding mutants had no detectable peptide transport activity. His-121 in hPEPT1 is not essential since mutation of this residue did not impair transport function. His-142 in hPEPT2 was found to play a significant role in the maintenance of transport function but was not found to be obligatory because the mutant had appreciable transport activity. The obligatory histidyl residue (His-57 in hPEPT1 and His-87 in hPEPT2) is located in an almost identical topological position in both transporters, near the extracellular surface of the second putative transmembrane domain. The second conserved histidyl residue is located in the fourth putative transmembrane domain in hPEPT1 as well as in hPEPT2. The third conserved histidyl residue is present in the cytoplasmic loop between the transmembrane domains 6 and 7 and is unlikely to play any significant role in the binding and translocation of H+ and this was supported by the findings that mutation of this histidyl residue in hPEPT1 did not interfere with transport function. The loss of transport function of hPEPT1 and hPEPT2, when His-57 in hPEPT1 and His-87 in hPEPT2 were mutated, was not due to alterations in protein expression because the expression levels of these mutants were similar to those of the respective wild type transporters in HeLa cells as assessed by immunoblot analysis. Confocal analysis of immunofluorescence in X. laevis oocytes expressing the wild type and the three histidine mutants of hPEPT1 showed that the transporter protein is expressed exclusively in the plasma membrane and that the level of expression is comparable among the wild type and the three mutants. These site-directed mutagenesis studies clearly show that His-57 in hPEPT1 and His-87 in hPEPT2 are the most critical histidyl residues necessary for the catalytic function of these transporters.

Using IL-2R/lymphocytes for predicting the clinical progression of patients with COVID-19

Effective laboratory markers for the estimation of disease severity and predicting the clinical progression of coronavirus disease-2019 (COVID-19) is urgently needed. Laboratory tests, including blood routine, cytokine profiles and infection markers, were collected from 389 confirmed COVID-19 patients. The included patients were classified into mild (n = 168), severe (n = 169) and critical groups (n = 52). The leukocytes, neutrophils, infection biomarkers [such as C-reactive protein (CRP), procalcitonin (PCT) and ferritin] and the concentrations of cytokines [interleukin (IL)-2R, IL-6, IL-8, IL-10 and tumor necrosis factor (TNF)-α] were significantly increased, while lymphocytes were significantly decreased with increased severity of illness. The amount of IL-2R was positively correlated with the other cytokines and negatively correlated with lymphocyte number. The ratio of IL-2R to lymphocytes was found to be remarkably increased in severe and critical patients. IL-2R/lymphocytes were superior compared with other markers for the identification of COVID-19 with critical illness, not only from mild but also from severe illness. Moreover, the cytokine profiles and IL-2R/lymphocytes were significantly decreased in recovered patients, but further increased in disease-deteriorated patients, which might be correlated with the outcome of COVID-19. Lymphopenia and increased levels of cytokines were closely associated with disease severity. The IL-2R/lymphocyte was a prominent biomarker for early identification of severe COVID-19 and predicting the clinical progression of the disease.

Controlled delivery of mesenchymal stem cells and growth factors using a nanofiber scaffold for tendon repair

Outcomes after tendon repair are often unsatisfactory, despite improvements in surgical techniques and rehabilitation methods. Recent studies aimed at enhancing repair have targeted the paucicellular nature of tendon for enhancing repair; however, most approaches for delivering growth factors and cells have not been designed for dense connective tissues such as tendon. Therefore, we developed a scaffold capable of delivering growth factors and cells in a surgically manageable form for tendon repair. Platelet-derived growth factor BB (PDGF-BB), along with adipose-derived mesenchymal stem cells (ASCs), were incorporated into a heparin/fibrin-based delivery system (HBDS). This hydrogel was then layered with an electrospun nanofiber poly(lactic-co-glycolic acid) (PLGA) backbone. The HBDS allowed for the concurrent delivery of PDGF-BB and ASCs in a controlled manner, while the PLGA backbone provided structural integrity for surgical handling and tendon implantation. In vitro studies verified that the cells remained viable, and that sustained growth factor release was achieved. In vivo studies in a large animal tendon model verified that the approach was clinically relevant, and that the cells remained viable in the tendon repair environment. Only a mild immunoresponse was seen at dissection, histologically, and at the mRNA level; fluorescently labeled ASCs and the scaffold were found at the repair site 9days post-operatively; and increased total DNA was observed in ASC-treated tendons. The novel layered scaffold has the potential for improving tendon healing due to its ability to deliver both cells and growth factors simultaneously in a surgically convenient manner.

Apolipoprotein A-I stimulates AMP-activated protein kinase and improves glucose metabolism

AIMS/HYPOTHESIS

In humans, one of the hallmarks of type 2 diabetes is a reduced plasma concentration of HDL and its major protein component, apolipoprotein A-I (APOA-I). However, it is unknown whether APOA-I directly protects against diabetes. The aim of this study was to characterise the functional role of APOA-I in glucose homeostasis.

METHODS

The effects of APOA-I on phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC), glucose uptake and endocytosis were analysed in C2C12 myocytes. Glucose metabolism was investigated in Apoa-I knockout (Apoa-I (-/-)) mice.

RESULTS

APOA-I was able to stimulate the phosphorylation of AMPK and ACC, and elevated glucose uptake in C2C12 myocytes. APOA-I could be endocytosed into C2C12 myotubes through a clathrin-dependent endocytotic process. Inhibition of endocytosis abrogated APOA-I-stimulated AMPK phosphorylation. In Apoa-I (-/-) mice, AMPK phosphorylation was reduced in skeletal muscle and liver, and expression of gluconeogenic enzymes was increased in liver. In addition, the Apoa-I (-/-) mice had increased fat content and compromised glucose tolerance.

CONCLUSIONS/INTERPRETATION

Our data indicate that APOA-I has a protective effect against diabetes via activation of AMPK. ApoA-I deletion in the mouse led to increased fat mass and impaired glucose tolerance.

Overexpression of the wild type p73 gene in human bladder cancer

p73, a first p53 relative, was recently identified and shown to be monoallelically expressed in a number of different human tissues. To determine the potential role of this gene in human bladder cancer, we investigated p73 expression levels, allelic expression patterns, and analysed p73 mutations in 23 unselected primary invasive bladder cancers with matched normal tissues and in seven bladder cancer cell lines. In a comparison between normal and tumor tissues using quantitative RT-PCR analysis, we found that p73 was overexpressed in 22/23 bladder cancers, sometimes as great as 20-fold. Allelic expression analysis using a C/T polymorphism in exon 2 and a newly identified T/C polymorphism in exon 5 revealed that p73 was biallelically expressed in both normal bladder and cancer tissues, suggesting that p73 is not imprinted in bladder tissue. Mutation screening of the p73 gene in bladder cancer DNAs using denaturing high-performance liquid chromatography analysis and DNA sequencing revealed no tumor-specific mutations in any coding exons of the p73 gene. These data suggest that the p73 is unlikely to be a tumor suppressor gene, but that overexpression of p73 may contribute to tumorigenesis in bladder cancer.