The Degree of Anxiety and Depression in Patients With Cardiovascular Diseases as Assessed Using a Mobile App: Cross-Sectional Study

BACKGROUND

Depression and anxiety are common comorbidities in cardiovascular clinic outpatients. Timely identification and intervention of these mental and psychological disorders can contribute to correct diagnosis, better prognosis, less medical expenses, and improved quality of life. The convenience of online doctor-patient communication platforms has increasingly attracted patients to online consultations. However, online health care and offline health care are very different. Research on how to identify psychological disorders in patients who engage in an online cardiology consultation is lacking.

OBJECTIVE

This study aimed to explore the feasibility of using a self-rating scale to assess mental illness among patients who consult with a cardiologist online and to compare the differences in anxiety and depression between online and offline patients.

METHODS

From June 2022 to July 2022, we conducted follow-up visits with 10,173 patients on the Haodf platform. We conducted detailed consultations with 286 patients who visited the same cardiologist in the outpatient department. We used the self-rated Generalized Anxiety Disorder (GAD-7) and Patient Health Questionnaire (PHQ-9) scales to assess anxiety and depression, respectively. We analyzed the influencing factors related to the degree of coordination of online patients. We also compared the prevalence of anxiety or depression between online and offline patients and analyzed the factors related to anxiety or depression.

RESULTS

Of the 10,173 online consultation patients, only 186 (1.8%) responded effectively. The response rate of the offline consultation patients was 96.5% (276/286). Frequent online communication and watching live video broadcasts were significantly related to effective responses from online patients (P<.001). The prevalence of anxiety (70/160, 43.7% vs 69/266, 25.8%; P<.001) or depression (78/160, 48.7% vs 74/266, 27.7%; P<.001) in online consultation patients was significantly higher than that in offline patients. In bivariate analyses, the factors related to anxiety included female sex, unemployment, no confirmed cardiovascular disease, and the online consultation mode, while smokers and those who underwent COVID-19 quarantine were less likely to present with anxiety. The factors related to depression included female sex, divorced or separated individuals, and the online consultation mode. COVID-19 quarantine was related with a lower likelihood of depression. BMI was negatively correlated with depression. In multiple ordered logistic regression analysis, women were more likely than men to present with anxiety (odds ratio [OR] 2.181, 95% CI 1.365-3.486; P=.001). Women (OR 1.664, 95% CI 1.082-2.559; P=.02) and online patients (OR 2.631, 95% CI 1.305-5.304; P=.007) were more likely to have depression.

CONCLUSIONS

Online patients had more anxiety or depression than offline patients. Anxiety was more prevalent in women, the unemployed, and those without confirmed cardiovascular disease. Women and divorced or separated individuals were more prone to depression. Increasing the frequency of doctor-patient communication and participating in video interactions can help improve patient cooperation.

Strain parameters for predicting the prognosis of non-ischemic dilated cardiomyopathy using cardiovascular magnetic resonance tissue feature tracking

BACKGROUND

A considerable number of non-ischemic dilated cardiomyopathy (NDCM) patients had been found to have normalized left ventricular (LV) size and systolic function with tailored medical treatments. Accordingly, we aimed to evaluate if strain parameters assessed by cardiovascular magnetic resonance (CMR) feature tracking (FT) analysis could predict the NDCM recovery.

METHODS

79 newly diagnosed NDCM patients who underwent baseline and follow-up CMR scans were enrolled. Recovery was defined as a current normalized LV size and systolic function evaluated by CMR.

RESULTS

Among 79 patients, 21 (27%) were confirmed recovered at a median follow-up of 36 months. Recovered patients presented with faster heart rates (HR) and larger body surface area (BSA) at baseline (P < 0.05). Compared to unrecovered patients, recovered pateints had a higher LV apical radial strain divided by basal radial strain (RSapi/bas) and a lower standard deviation of time to peak radial strain in 16 segments of the LV (SD16-TTPRS). According to a multivariate logistic regression model, RSapi/bas (P = 0.035) and SD16-TTPRS (P = 0.012) resulted as significant predictors for differentiation of recovered from unrecovered patients. The sensitivity and specificity of RSapi/bas and SD16-TTPRS for predicting recovered conditions were 76%, 67%, and 91%, 59%, with the area under the curve of 0.75 and 0.76, respectively. Further, Kaplan Meier survival analysis showed that patients with RSapi/bas ≥ 0.95% and SD16-FTPRS ≤ 111 ms had the highest recovery rate (65%, P = 0.027).

CONCLUSIONS

RSapi/bas and CMR SD16-TTPRS may be used as non-invasive parameters for predicting LV recovery in NDCM. This finding may be beneficial for subsequent treatments and prognosis of NDCM patients. Registration number: ChiCTR-POC-17012586.

Initial experience of robot-assisted Ivor-Lewis esophagectomy: 61 consecutive cases from a single Chinese institution

This study aims to report the technical details and preliminary outcomes of robot-assisted Ivor-Lewis esophagectomy (RAILE) using two different types of intrathoracic anastomosis from a single institution in China. From May 2015 to October 2017, 61 patients diagnosed with mid-lower esophageal cancer were treated with RAILE. The RAILE procedure was performed in two stages. The first 35 patients underwent circular end-to-end stapled intrathoracic anastomosis (stapled group), and the remaining 26 patients had a double-layered, completely hand-sewn intrathoracic anastomosis (hand-sewn group). Patient characteristics, surgical techniques, postoperative complications, and pathology outcomes were analyzed. The mean operating time and mean blood loss were 315.6 ± 59.4 minutes and 189.3 ± 95.8 mL, respectively. There was one patient who underwent conversion to thoracotomy. The 30-day and in-hospital mortality rates were 0%. Overall complications were observed in 22 patients (36.1%) according to the Clavien-Dindo (CD) and the Esophagectomy Complications Consensus Group (ECCG) classifications, of whom 6 patients (9.8%) had anastomotic leakage (ECCG, Type II). The median length of hospitalization (LOH) was 10 days (IQR, 5 days). Complete (R0) resection was achieved in all cases. The mean tumor size was 3.2 ± 1.5 cm, and the mean number of totally dissected lymph nodes was 19.3 ± 9.2. Regarding the operative outcomes between stapled and hand-sewn groups, there were no significant differences in the operative time (325.4 ± 66.6 vs. 302.3 ± 45.9 min, P = 0.114), blood loss (172.9 ± 74.1 vs. 211.5 ± 117.0 mL, P = 0.147), conversion rate (2.9 vs. 0%, P = 1.000), overall complication rate (37.1 vs. 34.6%, P = 0.839) or LOH (10 vs. 9.5 days, P = 0.415). RAILE using both stapled and hand-sewn intrathoracic anastomosis is safe and technically feasible with satisfactory perioperative outcomes for the treatment of mid-lower thoracic esophageal cancer.

Effects of Low-Dose Recombinant Human Brain Natriuretic Peptide on Anterior Myocardial Infarction Complicated by Cardiogenic Shock

Introduction

The mortality due to cardiogenic shock complicating acute myocardial infarction (AMI) is high even in patients with early revascularization. Infusion of low dose recombinant human brain natriuretic peptide (rhBNP) at the time of AMI is well tolerated and could improve cardiac function.

Objective

The objective of this study was to evaluate the hemodynamic effects of rhBNP in AMI patients revascularized by emergency percutaneous coronary intervention (PCI) who developed cardiogenic shock.

Methods

A total of 48 patients with acute ST segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock and whose hemodynamic status was improved following emergency PCI were enrolled. Patients were randomly assigned to rhBNP (n=25) and control (n=23) groups. In addition to standard therapy, study group individuals received rhBNP by continuous infusion at 0.005 µg kg⁻¹ min⁻¹ for 72 hours.

Results

Baseline characteristics, medications, and peak of cardiac troponin I (cTnI) were similar between both groups. rhBNP treatment resulted in consistently improved pulmonary capillary wedge pressure (PCWP) compared to the control group. Respectively, 7 and 9 patients died in experimental and control groups. No drug-related serious adverse events occurred in either group.

Conclusion

When added to standard care in stable patients with cardiogenic shock complicating anterior STEMI, low dose rhBNP improves PCWP and is well tolerated.

Protective Effects of Salvianolate on Contrast-Induced Nephropathy after Primary Percutaneous Coronary Intervention: A Prospective Multicenter Randomized Controlled Trial

OBJECTIVES

This study's aim was to evaluate the protective effects of salvianolate on contrast-induced nephropathy after primary percutaneous coronary intervention (PPCI) compared with normal saline (NS) hydration.

METHODS

We enrolled patients with acute myocardial infarction who underwent PPCI in 3 centers in Shanghai. The patients were randomly assigned to the salvianolate group or the NS group. The incidence of CIN, the changes in renal function parameters, and the occurrence of adverse events after the procedure were compared between the 2 groups. We used a multivariate logistic regression analysis to determine the independent correlates of CIN after PPCI.

RESULTS

A total of 484 patients were finally included in the statistical analysis. Compared with the control group, salvianolate reduced the incidence of CIN (9.1 vs. 16.3%, p = 0.018) after PPCI. The renal function parameters after PPCI in the salvianolate group were superior to those of the control group (p < 0.05). The composite adverse events rate was significantly lower in the salvianolate group within 1 month after the procedure (9.5 vs. 15.5%, p = 0.046). A higher peak of troponin I and loop diuretic therapy were the independent correlates of CIN after PPCI.

CONCLUSIONS

Salvianolate reduces the incidence of CIN and protects renal function after PPCI, and the effects were superior to those of NS hydration.

Regulation network analysis in the esophageal squamous cell carcinoma

BACKGROUND

The incidence of esophageal squamous cell carcinoma (ESCC) has high regional selectivity. The molecular mechanisms of ESCC are complex and involve multiple oncogenes, tumor suppressor genes, receptor tyrosine kinases, cytoplasmic enzymes, and tumor interstitial elements.

AIM

Here we used bioinformatics to obtain some important genes and pathways involved in ESCC.

MATERIALS AND METHODS

In this article, we did Affymetrix microarray data collection from three big databases, and then selected all the differentially expressed genes (DEGs) according to some principles. On this basis, we carried out regulation network analysis and pathway enrichment analysis, obtaining ESCC related regulation network analysis, after which we selected significant pathways on regulation network and established TF-pathway regulation network.

RESULTS

In the transcription factors (TFs) regulation network we found SP1, E2F1, USF2 and SP3 form a local network which suggested that these TFs might play a more important role in ESCC. Some key pathways were also identified, such as P53 signaling pathway, melanoma and prostate cancer pathways.

CONCLUSIONS

The identification of crucial molecular pathways involved in ESCC would ultimately improve therapeutic effects and facilitate the development of new treatment strategies.

Increased expression of paxillin is found in human oesophageal squamous cell carcinoma: a tissue microarray study

Oesophageal cancer is one of the most common cancers worldwide. Currently, the tumour, node, metastasis (TNM) staging system is the primary method for determining its extent and prognosis, however, data suggest this system does not predict prognosis accurately. Research has, therefore, concentrated on searching for specific biomarkers. Paxillin has been shown to play an important role in controlling cell spread and migration. Its over-expression is considered to correlate with the prognosis of some types of cancers, however, the relationship between paxillin expression and clinical outcome in oesophageal cancer has not been investigated. This study determined the expression of paxillin by immunohistochemistry on the tissue microarray of 100 oesophageal squamous cell cancer patients followed up for a mean of 55 months. Paxillin was over-expressed in tumours in 27/100 cases, compared with 6/100 cases for adjacent non-tumoural cells. No correlation occurred between expression of paxillin and overall patient survival, hence paxillin is not an effective prognostic marker in these patients.

Cloning of novel laccase isozyme genes from Trametes sp. AH28-2 and analyses of their differential expression

Three novel laccase isozyme genes, lacA, lacB, and lacC, have been identified from basidiomycete Trametes sp. AH28-2. These genes display a high similarity with other basidiomycete laccases at the amino acid level. An inferred TATA box and several putative CAAT, MRE, XRE, and CreA consensus sequences were identified in the lacA, lacB, and lacC promoter regions. Different from the TATA boxes of lacA and lacB at about -100, the TATA box of lacC is located at -172. For all the isozymes, copper ion is essential for laccase synthesis in Trametes sp. AH28-2. More interestingly, different aromatic compounds can selectively induce the production of distinct laccase isozymes, with o-toluidine inducing the expression of laccase A (LacA) while 3,5-dihydroxytoluene mainly stimulating the production of laccase B (LacB). Quantitative reverse transcriptase-polymerase chain reaction showed that the accumulation of laccase messenger RNA transcripts is accompanied by the increase of corresponding enzyme activity in cultures. The glucose-repression effect on laccase expression in Trametes sp. AH28-2 was also observed. Furthermore, lower Cu2+ concentration (lower than 0.5 mM) can induce LacA and a novel laccase (LacC), and the latter will disappear when Cu2+ concentration is increased up to 1-2 mM. Upon induction by 3,5-dihydroxytoluene, the ratio of LacA to LacB decreased in the later phase of induction.

Selective induction, purification and characterization of a laccase isozyme from the basidiomycete Trametes sp. AH28-2

The white-rot fungus Trametes sp. AH28-2 can synthesize extracellular laccase by induction in cellobiose-based liquid culture medium. Both yields and composition of laccase isozymes, produced by Trametes sp. AH28-2, would be quite different with induction by different small-molecule aromatic compounds, o-toluidine, guaiacol and 3,5-dihydroxytoluene, which affected microbial growth and the synthesis of laccase isozymes differentially. Higher concentrations of the three inducers could considerably increase laccase isozymes yields but not change the laccase composition. Coculturing of Trametes sp. AH28-2 with either Aspergillus oryzae or Gloeophyllum trabeum showed a few effects on laccase production. Laccase isozyme, laccase B, was selectively induced by 3,5-dihydroxytoluene and purified to homogeneity by two-step chromatography. Purified laccase B appeared as blue, with a broad peak at about 600 nm and a shoulder peak at about 330 nm. The ratio of absorbance at 280 nm to that at 600 nm was 21. Every molecule of laccase B had approximately four copper atoms. Molecular mass of laccase B was estimated to be 74 kDa on SDS-PAGE, 72 kDa by FPLC and was determined to be 71 454 Da by mass spectrum. After being treated with N-glycosidase F, laccase B lost 25% of its molecular mass. The isoelectric point of laccase B was 4.0. Its optimal pH and temperature for oxidizing guaiacol were respectively 4.7 and 45 C. The half-life of the enzyme at 60 C was 14.0 min. The enzyme showed a good stability in a range of pH value of 3.5-7.5. The K(m) values of the enzyme toward substrates syringaldazine, guaiacol, ABTS, and DMOP were respectively 28.0, 1249.0, 177.0 and 109.8 μM. The corresponding V(max) are 504.0, 1910.0, 117.4 and 159.0 μM min(-1) mg(-1). In addition, activity of laccase B was inhibited strongly by sodium azide and cyanide, mildly by SDS and trifluoroacetic acid, but only weakly by dimethyl sulfoxide.

Tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunit subtypes

We report here the tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunits. Northern blot analysis demonstrated that human alpha2delta-1, -2, and -3 mRNA all had high levels of expression in brain, heart and skeletal muscle. However, the highest expression of human alpha2delta-2 mRNA was found in lung. Human alpha2delta-1, -2, and -3 mRNAs were detected in all portions of brain tested. Western blotting revealed that alpha2delta-2 protein was predominantly expressed in cerebellar cortex (brain) and undetectable in lung. The dissociation between mRNA and protein levels of human alpha2delta-2 in lung suggests possible post-transcriptional regulation. Although mouse alpha2delta-1 proteins exhibited a similar tissue distribution profile as that of human, tissue distribution of mouse alpha2delta-2 and -3 mRNA revealed a different profile. Mouse alpha2delta-3 mRNA was restricted to brain and mouse alpha2delta-2 mRNA was not detectable in lung. Gel electrophoresis under a reduced condition resulted in a mobility shift of both alpha2delta-1 and alpha2delta-2 proteins, suggesting that alpha2 and delta of alpha2delta-2 protein are linked by disulfide bond as are alpha2 and delta of alpha2delta-1. Scatchard plots revealed a single population of gabapentin binding sites for human alpha2delta-2 with the KD value twofold higher than that of porcine alpha2delta-1 (156 +/- 25 nm vs. 72 +/- 9 nm). Inhibition of gabapentin binding to alpha2delta-2 by selected amino acids and gabapentin analogs produced a binding profile similar, but not identical to that of alpha2delta-1.

[Factors of laccase producing and fermentation conditions by a new white-rot fungus AH28-2]

White-rot fungus AH28-2, a newly isolated strain, produced effectively laccase by induction when grown on a synthetic medium. Aromatic compounds of low molecular weight had an inducing influence on laccase production and its isoenzyme compositions. The using of o-toluidine or syringic acid had the best inducing effect. Cu2+ concentration in medium had distinguished effect on laccase production. Enzyme activity was notably increased by Cu2+ and reached the maximum when Cu2+ final concentration was 5 mumol/L. Mn2+ inhibited the synthesis of laccase. Carbon and nitrogen limitation were not beneficial to laccase synthesis, while high nutrient organic medium was beneficial to the growth of cell and the synthesis of laccase. Using cellobiose as the sole carbon source, the highest level enzyme activity reached 82,923. 7 u/L under the condition of optimum fermentation with ABTS as substrate. This enzyme activity was 2.9-fold higher compared to the reported data on international references in recent years.

Ligand binding and structural properties of segments of GABAA receptor alpha 1 subunit overexpressed in Escherichia coli

The gamma-aminobutyric acid, type A (GABA(A)), receptor is the target for numerous therapeutic compounds. In the present study, the Gln(28)-Leu(296), Gln(28)-Arg(276), Gln(28)-Arg(248), and Gln(28)-Glu(165) (numbering of bovine precursor protein) segments of its alpha(1) subunit were overexpressed in Escherichia coli, along with Cys(166)-Leu(296) produced previously, for structural analysis by circular dichroism and ligand binding studies by fluorescence spectroscopy. Results showed that the protein segments were rich in beta-sheet structures. Binding of the fluorescent benzodiazepine Bodipy-FL Ro-1986 was evident from fluorescence resonance energy transfer and fluorescence anisotropy measurements. The binding affinity was in the micromolar range. The binding was attributable more to Cys(166)-Leu(296) than to Gln(28)-Glu(165) and was inhibited by known central benzodiazepine site ligands. Three point mutations, Y187A, T234A, and Y237A, were found to perturb protein secondary structures. Studies with the single Trp mutants W198Y and W273Y indicated that Trp(273) was closer to the binding site than Trp(198).

[Community characteristics of rare trees at Dalaoling of Three-Gorge reservoir area in western Hubei Province]

The quantitative characteristics, plant frequency in layers and species diversity of David involucrata var. vilnoriniara, Euptlea pleiosperma, Stewartia sinensis and Pterostyrax psilophtila communities at Dalaoling National Forest Park Reserve of Yichang were studied qualitatively and quantitatively. The community composition and structure were made clear, the succession courses and stages of the communities were revealed, and the role of these rare trees on the succession course of communities and the cause of being in imminent danger were analyzed, which provided a theoretical basis for protecting the rare trees in the Three-Gorge reservoir area.

NMR studies of Bacillus subtilis tRNA(Trp) hyperexpressed in Escherichia coli. Assignment of imino proton signals and determination of thermal stability

15N-Labeled Bacillus subtilis tRNA(Trp) wild type and a series of mutants were hyperexpressed in Escherichia coli and purified for NMR studies with the use of two-dimensional nuclear Overhauser effect spectroscopy (NOESY) and heteronuclear single quantum correlation (HSQC) and three-dimensional NOESY-HSQC techniques. These made possible chemical shift assignments of imino protons and determination of the thermal stability of the tRNA(Trp) molecules. Almost all of the imino protons in the helical regions and the tertiary base pairs were assigned, except three imino protons of the AU base pairs whose peaks were not clearly observed. Several base triplets found in the crystal structure of tRNA were observed in the present study as well. These studies also revealed two components of tRNA(Trp), which could not be separated by high pressure liquid chromatography, corresponding to s(4)U and U at position 8 of the tRNA(Trp), as indicated by two different sets of peaks for the TpsiC and D arms. The modification at position 8 altered the local conformation of the core region of the tRNA. Thermal unfolding experiments showed that the unfolding process is cooperative in the presence of a high concentration of magnesium ions and that the component corresponding to the s(4)U8 is more stable than the U8 component, thus providing evidence that the thiolation of U8 stabilizes the tertiary structure of tRNA.

Increasing the thermostability of D-xylose isomerase by introduction of a proline into the turn of a random coil

Thermostability can be increased by introducing prolines at suitable sites in target proteins. Two single (G138P, G247D) mutants and one double (G138P/G247D) mutant of xylose isomerase from Streptomyces diastaticus No.7, strain M1033 have been constructed by site-directed mutagenesis. With respect to the wild-type enzyme, G138P showed about a 100% increase in thermostability, and G247D showed an increased catalytic activity. Significantly, the double mutant, G138P/G247D displayed even higher activity than G247D and better heat stability than G138P. Its half life was about 2.5-fold greater than the wild-type enzyme, using xylose as a substrate. Molecular modelling suggested that the introduction of a proline residue in the turn of a random coil may cause the surrounding conformation to be tightened by reducing the backbone flexibility. The change in thermostability can, therefore, be explained based on changes in the molecular rigidity. Furthermore, the improvements in the properties of the double mutant indicated that the advantages of two single mutants can be combined effectively.

Detection of premalignant oral lesions in hamsters with an endoscopic fluorescence imaging system

BACKGROUND

Various methods of detecting cancer with fluorescence have been developed. One type of fluorescence is based on the tumor-localizing properties of certain dyes. However, the phototoxicity of most known tumor-localizing dyes hinders the safe use of such diagnostic methods. The authors have developed a fluorescence imaging system to detect the distribution of a nontoxic dye, fluorescein, and they have evaluated the feasibility of the system by using it to detect oral dysplastic lesions in hamsters.

METHODS

Dysplasia was induced in the cheek pouches of hamsters by application of the carcinogen 9,10-dimethyl-1,2-benzantracene. Fluorescein was administered to the hamsters either intravenously or orally before the fluorescence examination. The endoscopic fluorescence system produced dye-distribution images of both treated and control pouches. Two fluorescence images in different spectral regions were processed for each dye image. Biopsy material from both pouches was examined histopathologically.

RESULTS

The accumulation of fluorescein was detected in 22 of 23 specimens containing dysplastic lesions.

CONCLUSIONS

These results demonstrate the utility of this fluorescein accumulation method in the detection of dysplasia. The accumulation of fluorescein in dysplastic lesions may point to acidification of interstitial medium in such lesions.

Delineation of a membrane-proximal beta-rich domain in the GABAA receptor by progressive deletions

The type A gamma-aminobutyric acid (GABAA) receptor plays a major inhibitory role in the central nervous system. Structural elucidation of the GABAA receptor has been impeded by the large size of the receptor. We present here the delineation of a minimal structural domain as the first step of dissecting the receptor structure. This was achieved through prediction-assisted progressive deletions: the prediction of a candidate structural domain rich in beta-strands with no close similarity to known structures was tested by deleting putative secondary structure elements from the ends of the proposed domain, as well as mutations within the terminal secondary structures. Such progressive deletions revealed the limits of an integral domain, spanning Cys180 to Met293 (numbering of human alpha1 subunit). Below these limits the intact domain structure, as indicated by its circular dichroism, collapses. Based on its putative position, this domain is provisionally designated the membrane-proximal beta-rich domain of GABAA receptor. The inclusion of sequences from the first two out of four previously suggested transmembrane segments and one of the two conserved Cys residues in this domain defines important constraints to the receptor structure.

Possible involvement of P13K in prolactin-stimulated milk product formation and iodide transport in mouse mammary explants

The in vitro effect of wortmannin, an inhibitor of P13 kinase, on prolactin (PRL) stimulated p70S6K, iodide transport, and milk product synthesis were investigated in cultured mouse mammary tissues. Mouse mammary gland explants were initially incubated for 24 hr in media M199 containing 1 microg/ml insulin and 10(-7)M cortisol. A subsequent treatment with wortmannin impeded, in a dose-dependent fashion, the PRL stimulation of casein, lipid, and lactose synthesis as well as the PRL stimulation of iodide transport. Rapamycin (25 ng/ml), an inhibitor of p70S6K, also inhibited the effect of PRL on iodide transport; this drug was earlier shown to inhibit PRL effects on milk product synthesis. These results suggest the possible involvement of p70S6K and P13-kinase in PRL-stimulated milk product formation and iodide transport in mouse mammary explants. Since wortmannin caused a diminished cellular content of p70S6K and a reduced extent of P70S6K migration in polyacrylamide gels (likely due to dephosphorylation), P13-kinase likely lies upstream in the PRL signaling pathway for p70S6K activation.

Fragment of GABA(A) receptor containing key ligand-binding residues overexpressed in Escherichia coli

GABA(A) receptor plays a major role in inhibitory synaptic transmission in the central nervous system and is the target of drugs such as the benzodiazepine tranquilizers. The polymeric membrane protein nature of GABA(A) receptor has rendered structural elucidation of the receptor a formidable task, greatly hampering structure-based drug design. We report here the first expression in Escherichia coli of a fragment of GABA(A) receptor. This 131-residue fragment, spanning Cys166 to Leu296 of human GABAA receptor alpha1 subunit, contains residues previously suggested to be involved in benzodiazepine binding. The overexpressed non-fusion recombinant protein was purified to near homogeneity and characterized by circular dichroism (CD), which showed that the recombinant protein has well defined secondary structures where beta-strands are dominant. The stability of the secondary structures was demonstrated by CD spectra at high pH and elevated temperature. Excluding part of the sequences from the carboxyl terminal of the fragment resulted in dramatic changes in the secondary structures comparable to the effects caused by SDS denaturation. Our results therefore suggest that the 131-residue fragment harbors an integral structural domain of the receptor. The overexpression of the recombinant protein fragment thus opens the way to the biochemical and structural studies of a functionally important region of the receptor, and exemplifies an effective approach of expression and characterization that potentially may be extended to other members of the ligand gated channel receptor superfamily, to which the GABA(A) receptor belongs.

Effect of rapamycin on prolactin-stimulated S6 kinase activity and milk product formation in mouse mammary explants

The in vitro effects of rapamycin on prolactin (PRL)-stimulated S6 kinase activity and milk product synthesis were investigated in cultured mouse mammary tissues. Mouse mammary gland explants were initially incubated for 24 h in M199 media containing 1 microgram/ml insulin and 10(-7) M cortisol. A subsequent treatment of the tissues with 1 microgram/ml PRL for 12 h caused a 98% increase in S6 kinase activity in the cytosolic fraction; effects were not observed at earlier times. PRL at or above 500 ng/ml was needed to elicit a maximum stimulation of S6 kinase activity, and this response was specific for lactogenic hormones (PRL, hPL, hGH). Rapamycin, an inhibitor of 70 K S6 kinase, was employed to assess the possible physiological role of S6 kinase in the PRL stimulation of milk product formation. Rapamycin (25-100 ng/ml) impeded, in a dose-dependent fashion, the PRL stimulation of casein, lipid and lactose synthesis in concert with its inhibition of cytoplasmic S6 kinase activity. These results suggest a possible role for the activation of 70 K kinase in the signalling pathway for the PRL regulation of milk product synthesis in the mammary gland.

Prolactin's effects on lipoprotein lipase (LPL) activity and on LPL mRNA levels in cultured mouse mammary gland explants

The in vitro effects of prolactin (PRL) on lipoprotein lipase (LPL) activity and on LPL mRNA levels were studied in cultured mammary tissues derived from mid-pregnant mice. Mouse mammary gland tissues were initially incubated for 24 hr in M199 media containing 1 microg/ml insulin and 10(-7) M cortisol. A subsequent treatment of the tissues with 1 microg/ml PRL caused a 76% increase in heparin-releasable LPL (hrLPL) activity after 24 hr. A significant increase in LPL activity was detected 16 hr after PRL addition, but not at earlier times. PRL at 100 ng/ml elicited a maximum stimulation of LPL activity. When Northern hybridization techniques were employed, PRL was also found to increase the tissue content of LPL mRNA; this effect was initially detected after a 6-hr PRL treatment employing PRL concentrations of 50 ng/ml and above. Specificity studies revealed that only lactogenic hormones stimulated LPL activity and LPL mRNA accumulation in cultured mammary tissues. PRL also expressed a small (25% increase), but significant, effect on ATP citrate-lyase activity in mammary tissues cultured for more than 6 hr with the hormone.

Capillary-to-fiber surface ratio in rat fast-twitch hindlimb muscles after chronic electrical stimulation

We examined the relative plasticity of capillaries and fiber mitochondria in rat fast-twitch hindlimb muscles in response to chronic electrical stimulation. Specifically we addressed whether the size of the capillary-fiber interface increases in proportion to fiber mitochondrial volume, inasmuch as fiber aerobic capacity increases severalfold with chronic stimulation. Tibialis anterior and extensor digitorum longus muscles of six rats [367 +/- 17 (SD) g body wt] were stimulated (10 Hz, 8 h/day, 7 days/wk) for 28 consecutive days. Subsequently they were perfusion fixed in situ and stimulated, and contralateral control samples from the midbelly were processed for electron microscopy and morphometry. Capillary length density, capillary-to-fiber ratio, and fiber mitochondrial volume density increased two- to threefold in stimulated muscles, with no change in fiber or capillary diameter. Capillary-to-fiber surface area ratio per fiber unit mitochondrial volume was unchanged in stimulated muscles compared with contralateral controls, indicating a proportional increase in the size of the capillary-fiber interface and fiber mitochondrial volume in the muscles after chronic electrical stimulation.

VEGF gene expression is upregulated in electrically stimulated rat skeletal muscle

Vascular endothelial growth factor (VEGF; also called vascular permeability factor) is a secreted mitogen with distinct target cell specificity for vascular endothelial cells. Hypoxia upregulates VEGF expression, making it a likely mediator of the angiogenesis that occurs in poorly perfused tissues. The purpose of this study was to determine whether VEGF gene expression is upregulated in chronically stimulated skeletal muscles, where hypoxia is thought to trigger the growth of blood vessels. The right anterior tibialis and extensor digitorum longus muscles of 12 rats were stimulated electrically (10 Hz, 300 microseconds pulses) for up to 21 days by way of the peroneal motor nerve. The contralateral muscles served as control. Northern analysis showed that VEGF mRNA levels increased by approximately sixfold after 4 days of stimulation and then decreased gradually over the next several days. VEGF mRNA levels were still elevated by two- to threefold after 21 days of stimulation. Higher VEGF mRNA levels in the early stages of muscle stimulation and gradually decreasing levels in later stages are consistent with a metabolic hypothesis in which tissue oxygenation controls VEGF expression. These studies support the hypothesis that VEGF has a physiological role in promoting angiogenesis in stimulated skeletal muscle.

Long-term electrical stimulation of rabbit skeletal muscle increases growth of paired arteries and veins

We tested whether chronic stimulation of skeletal muscle can increase the growth of paired arteries and veins in rabbit extensor digitorum longus muscle (EDL). The right EDL of female New Zealand White rabbits was stimulated via the common peroneal nerve at 10 Hz using 300 microseconds square waves at 3-4 V. Two-hour periods of stimulation was alternated with 4-h periods of rest, 7 days/wk for approximately 60 days. The left EDL served as control. The hindlimb vascular system was maximally dilated and perfuse-fixed with 3% glutaraldehyde and 2% paraformaldehyde at arterial and venous pressures of 80-100 and 15-20 mmHg, respectively. Muscles were postfixed in OsO4 and embedded in EPOX 812 resin. One millimeter-thick transverse sections were cut at uniform locations through the entire breadth of the muscle and analyzed using videomicroscopy along with computerized morphometric and stereological techniques. All paired arteries and veins on each full muscle section were analyzed. Chronic muscle stimulation caused the wall volume of paired arteries and veins to increase by an average of approximately twofold and the lumen volume to increase by an average of approximately threefold compared with the contralateral muscles. The wall-to-lumen area ratio of the arteries and veins was not affected. Muscle stimulation also caused the numerical density of arteries having a diameter > 100 microns to increase by approximately fourfold and the density of veins having a perimeter > 500 microns to increase by approximately 10-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Miniaturized electrical stimulator with controllable duty cycles

A stimulator with adjustable duty cycles is described for chronic electrical stimulation of skeletal muscles by way of a motor nerve. The stimulator is unique in that it can stimulate a muscle or group of muscles for 2-h intervals that alternate with variable periods of rest (2, 4, 6, 8, or 10 h). A given duty cycle is selected with a rotary switch at the beginning of an experiment and will continue automatically, without human intervention, for the duration of the experiment. Other features include an adjustable voltage output, a stimulation indicator light-emitting diode (LED), and a low-battery indicator LED. The stimulator is powered by two 9-V batteries or can be used with a bench-top power supply. The stimulation frequency (10 Hz) and pulse width (300 microseconds) are fixed in our design but can be changed to other values by substituting two of the resistors and one capacitor in accordance with simple formulas. We have used the stimulator in rat and rabbit experiments to stimulate the anterior tibialis and extensor digitorum longus muscles for up to 60 days. The timing and output of the stimulator were found to be stable and accurate over the entire 60-day period. The stimulator and batteries were carried in a jacket worn by the rabbits. In the rat experiments, the stimulator was used in a remote fashion with the electrical leads connected to the animals by way of a tethering system. In both animals, the electrodes were implanted adjacent to the common peroneal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

A stereological method for estimating length density of the arterial vascular system

We developed a stereological method for quantitating length density (Lv; vessel length per unit reference volume) of the arterial system. Accurate estimation of Lv for a sparse system of blood vessels in a three-dimensional specimen requires information on individual vessel orientation. The method we present extracts the necessary information on vessel orientation from profile geometry. Major and minor diameters of elliptical profiles of sectioned tubular structures are used to calculate Lv. The method does not require special sectioning alignment and does not assume a prior distribution of blood vessels; however, the method does assume that arteries are cylindrical. A physical model consisting of boiled spaghetti mixed with agar in a cylinder was used to test the stereological method. Measurements of over 1,000 elliptical profiles in 5 separate trials have demonstrated that the method can accurately estimate Lv with < 5% error even when tortuosity is high, i.e., when anisotrophy coefficient is 1.55. This method may facilitate a better understanding of the mechanisms of artery growth by making it possible to quantify linear growth of the arterial system.

Evidence for heat-stable liver cytosol substance(s) capable of causing oxidative activation of fructose 1,6-bisphosphatase

The endogenous fructose 1,6-bisphosphatase (FBPase) in chicken liver extract undergoes a drastic increase in activity if the pH of the extract is in the alkaline range. Greater and more consistent activation occurs when purified FBPase, placed inside dialysis sack, is incubated in liver extract. Maximal activation (over 16-fold) is accompanied by the disappearance of 4 highly reactive sulfhydryl groups (SH) per molecule of enzyme. The activating effect of the extract remains essentially unchanged after heating to 100 degrees C. Activation can be reversed by dithiothreitol. These data show the existence in liver cytosol of heat-stable substance(s) capable of activating FBPase presumably by forming disulfide bonds with the enzyme's highly reactive SH groups.