Physiological demands and physical performance determinants of a new firefighting simulation test.

The study aimed to examine physiological responses of firefighters performing a firefighting simulation test (FST) and to determine the relationship between physical fitness parameters and FST performance. Aerobic fitness, muscular strength, muscular endurance, and anaerobic capabilities were evaluated in 37 firefighters (21-profesionals and 16-volunteers firefighters). Furthermore, participants carried out the FST during which we measured performance, respiratory gas exchange, heart rate (HR), perceived exertion and blood lactate concentrations. Males were significantly faster than females for all tasks of the FST (p < 0.01); however, final performance score (16.5 ± 2.9 and 14.5 ± 2.6 points for males and females, respectively), HR (94.0 ± 2.0% and 93.7 ± 2.3% of HRmax) and perceived exertion (8.1 ± 0.9 and 7.1 ± 1.3) were not significantly different. Prediction of FST performance by LASSO regression revealed a model that included mainly aerobic capacity and maximal strength. In conclusion, FST challenged both aerobic and anaerobic energy metabolisms for both males and females and requires various physiological abilities to perform. Practitioner Summary: For the safety of firefighters and victims, firefighters must meet minimum physical requirements. 37 firefighters performed physical tests and a new firefighting test implemented for the recruitment of firefighters in France. The results revealed that this test is strenuous and that performance is associated with cardiorespiratory fitness and muscular strength. Abbreviations: V̇O2: oxygen consumption; V̇CO2: carbon dioxyde production; V̇E: expired ventilation; RER: respiratory exchange ratio; FST: firefighting simulation test; MAS: maximal aerobic speed; HR: heart rate; RPE: rating of perceived exertion; MVC: maximum voluntary contraction; IMTP: isometric mid-thigh pull; TTE: time to exhaustion; Ppeak: peak power; Pmean: mean power; LASSO: least absolute shrinkage and selection operator; La-: blood lactate concentration.

Quantitative feature analysis of continuous analytic wavelet transforms of electrocardiography and electromyography.

Theoretical and practical advances in time-frequency analysis, in general, and the continuous wavelet transform (CWT), in particular, have increased over the last two decades. Although the Morlet wavelet has been the default choice for wavelet analysis, a new family of analytic wavelets, known as generalized Morse wavelets, which subsume several other analytic wavelet families, have been increasingly employed due to their time and frequency localization benefits and their utility in isolating and extracting quantifiable features in the time-frequency domain. The current paper describes two practical applications of analysing the features obtained from the generalized Morse CWT: (i) electromyography, for isolating important features in muscle bursts during skating, and (ii) electrocardiography, for assessing heart rate variability, which is represented as the ridge of the main transform frequency band. These features are subsequently quantified to facilitate exploration of the underlying physiological processes from which the signals were generated.This article is part of the theme issue 'Redundancy rules: the continuous wavelet transform comes of age'.

The physical and chemical disruption of human hair after bleaching - studies by transmission electron microscopy and redox proteomics.

OBJECTIVE: To understand the structural and chemical effects of cosmetic peroxide bleaching on human hair. METHODS: Human hair was progressively bleached using alkaline peroxide-persulphate treatment. Proteins lost through leaching were examined using amino acid analysis and mass spectrometric sequencing. Fibre damage was assessed using transmission electron microscopy, amino acid analysis and redox proteomics. RESULTS: Protein loss through leaching increased with bleaching severity. Leached proteins were not limited to the cuticle, but also included cortical intermediate filaments and matrix keratin-associated proteins. The leached proteins were progressively oxidized as bleaching severity increased. Bleached fibres demonstrated substantial damage to the cuticle layers and to the cortex. Extensive melanin granule degradation was present after the mildest bleach treatment. Protein oxidation in bleached fibres was principally in cortical intermediate filaments - the most abundant hair proteins - and targeted the sulphur-containing amino acids, particularly the conversion of cystine disulphide bonds to cysteic acid. CONCLUSION: Peroxide chemical treatments quickly access the cortex, causing untargeted oxidative damage across the fibre in addition to the desired loss of melanin. Peroxide ingress is likely facilitated by the considerable structural degradation caused to the cuticle layers of hair fibres. The consequences of the peroxide action within the cuticle and cortex are oxidation of the proteins, and subsequent protein loss from the fibre that correlates to bleaching severity.

Usefulness of High-Quality Core Genome Single-Nucleotide Variant Analysis for Subtyping the Highly Clonal and the Most Prevalent Salmonella enterica Serovar Heidelberg Clone in the Context of Outbreak Investigations.

Salmonella enterica serovar Heidelberg is the second most frequently occurring serovar in Quebec and the third-most prevalent in Canada. Given that conventional pulsed-field gel electrophoresis (PFGE) subtyping for common Salmonella serovars, such as S. Heidelberg, yields identical subtypes for the majority of isolates recovered, public health laboratories are desperate for new subtyping tools to resolve highly clonal S. Heidelberg strains involved in outbreak events. As PFGE was unable to discriminate isolates from three epidemiologically distinct outbreaks in Quebec, this study was conducted to evaluate whole-genome sequencing (WGS) and phylogenetic analysis as an alternative to conventional subtyping tools. Genomes of 46 isolates from 3 Quebec outbreaks (2012, 2013, and 2014) supported by strong epidemiological evidence were sequenced and analyzed using a high-quality core genome single-nucleotide variant (hqSNV) bioinformatics approach (SNV phylogenomics [SNVphyl] pipeline). Outbreaks were indistinguishable by conventional PFGE subtyping, exhibiting the same PFGE pattern (SHEXAI.0001/SHEBNI.0001). Phylogenetic analysis based on hqSNVs extracted from WGS separated the outbreak isolates into three distinct groups, 100% concordant with the epidemiological data. The minimum and maximum number of hqSNVs between isolates from the same outbreak was 0 and 4, respectively, while >59 hqSNVs were measured between 2 previously indistinguishable outbreaks having the same PFGE and phage type, thus corroborating their distinction as separate unrelated outbreaks. This study demonstrates that despite the previously reported high clonality of this serovar, the WGS-based hqSNV approach is a superior typing method, capable of resolving events that were previously indistinguishable using classic subtyping tools.

Molecular epidemiology and antimicrobial susceptibility profiles of methicillin-resistant Staphylococcus aureus blood culture isolates: results of the Quebec Provincial Surveillance Programme.

The objectives of this study were to characterize methicillin-resistant Staphylococcus aureus (MRSA) blood culture isolates and to determine their relative importance in both nosocomial and community-acquired infections. A total of 535 MRSA blood culture isolates were analysed. In vitro susceptibility to 14 agents was determined. The genes nuc, mecA and coding for PVL toxin were identified by PCR. All isolates were characterized by PFGE or spa typing to assess their genomic relationships. Most MRSA isolates were retrieved from nosocomial bloodstream infections (474, 89%) and were of the CMRSA2 genotype. Healthcare-associated (HA)-MRSA bloodstream infections were associated with older age (70-89 years, P = 0·002) and most often secondary to central line infections (P = 0·005). Among MRSA strains associated with community-acquired (CA)-MRSA, 28·8% were isolated in intravenous drug users. CA-MRSA genotypes were more frequently found in young adults (20-39 years, P < 0·0001) with skin/soft tissue as the primary sources of infection (P = 0·006). CMRSA10 genotype was the predominant CA-MRSA strain. All MRSA isolates were susceptible to doxycycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin. Both the presence of the genes coding for PVL toxin (89·8%) and susceptibility to clindamycin (86·5%) were predictive of CA-MRSA genotypes. Whereas in the USA, HA-MRSA have been replaced by USA300 (CMRSA10) clone as the predominant MRSA strain type in positive blood cultures from hospitalized patients, this phenomenon has not been observed in the province of Quebec.

The accuracy of prehospital triage decisions in English trauma networks - a case-cohort study.

BACKGROUND: Care for injured patients in England is provided by inclusive regional trauma networks. Ambulance services use triage tools to identify patients with major trauma who would benefit from expedited Major Trauma Centre (MTC) care. However, there has been no investigation of triage performance, despite its role in ensuring effective and efficient MTC care. This study aimed to investigate the accuracy of prehospital major trauma triage in representative English trauma networks. METHODS: A diagnostic case-cohort study was performed between November 2019 and February 2020 in 4 English regional trauma networks as part of the Major Trauma Triage Study (MATTS). Consecutive patients with acute injury presenting to participating ambulance services were included, together with all reference standard positive cases, and matched to data from the English national major trauma database. The index test was prehospital provider triage decision making, with a positive result defined as patient transport with a pre-alert call to the MTC. The primary reference standard was a consensus definition of serious injury that would benefit from expedited major trauma centre care. Secondary analyses explored different reference standards and compared theoretical triage tool accuracy to real-life triage decisions. RESULTS: The complete-case case-cohort sample consisted of 2,757 patients, including 959 primary reference standard positive patients. The prevalence of major trauma meeting the primary reference standard definition was 3.1% (n=54/1,722, 95% CI 2.3 - 4.0). Observed prehospital provider triage decisions demonstrated overall sensitivity of 46.7% (n=446/959, 95% CI 43.5-49.9) and specificity of 94.5% (n=1,703/1,798, 95% CI 93.4-95.6) for the primary reference standard. There was a clear trend of decreasing sensitivity and increasing specificity from younger to older age groups. Prehospital provider triage decisions commonly differed from the theoretical triage tool result, with ambulance service clinician judgement resulting in higher specificity. CONCLUSIONS: Prehospital decision making for injured patients in English trauma networks demonstrated high specificity and low sensitivity, consistent with the targets for cost-effective triage defined in previous economic evaluations. Actual triage decisions differed from theoretical triage tool results, with a decreasing sensitivity and increasing specificity from younger to older ages.

Investigating the origins of nanostructural variations in differential ethnic hair types using X-ray scattering techniques.

OBJECTIVE: Human hair is a major determinant of visual ethnic differentiation. Although hair types are celebrated as part of our ethnic diversity, the approach to hair care has made the assumption that hair types are structurally and chemically similar. Although this is clearly not the case at the macroscopic level, the intervention of many hair treatments is at the nanoscopic and molecular levels. The purpose of the work presented here is to identify the main nanoscopic and molecular hierarchical differences across five different ethnic hair types from hair fibres taken exclusively from the scalp. These are Afro (subdivided into elastic 'rubber' and softer non-elastic 'soft'), Chinese, European and Mullato (mixed race). METHODS: Small angle X-Ray scattering (SAXS) is a technique capable of resolving nanostructural variations in complex materials. Individual hair fibres from different ethnic hair types were used to investigate structural features found in common and also specific to each type. Simultaneous wide angle X-Ray scattering (WAXS) was used to analyse the submolecular level structure of the fibrous keratin present. The data sets from both techniques were analysed with principal component analysis (PCA) to identify underlying variables. RESULTS: Principal component analysis of both SAXS and WAXS data was shown to discriminate the scattering signal between different hair types. The X-ray scattering results show a common underlying keratin intermediate filament (KIF) structure. However, distinct differences were observed in the preferential orientation and intensity signal from the lipid component of the hair. In addition, differences were observed in the intensity distribution of the very low-angle sample-dependent diffuse scatter surrounding the 'beamstop.' CONCLUSION: The results indicate that the fibrous keratin scaffold remains consistent between ethnic hair types. The hierarchies made by these may be modulated by variation in the content of keratin-associated proteins (KAPs) and lipids that alter the interfacial structures and lead to macroscopic differences in hair morphology.

Redox proteomic evaluation of bleaching and alkali damage in human hair.

OBJECTIVE: Protein modification and damage in human hair, resulting from environmental, cosmetic and grooming stresses, create changes to visual and tactile characteristics and correlates with consumer perception of quality. This study outlines molecular-level evaluation of modification resulting from peroxide (bleaching) and alkaline straightening (relaxing) treatments. METHODS: Redox proteomic profiling of virgin, bleached and relaxed hair tresses was performed, with comprehensive qualitative characterization of modification and semi-quantitative evaluation of damage through adaptation of a new damage scoring system. Modifications were mapped to specific locations in the hair proteome and a range of potential damage marker peptides identified. RESULTS: Virgin hair contained a baseline level of modification, consistent with environmental oxidative insult during hair growth. Hydrogen peroxide bleaching resulted in significantly increased levels of oxidative damage observable at the molecular level. This treatment also resulted in enhanced levels of dehydroalanine and dehydration products; modifications typically associated with alkali or thermal treatment and not previously been reported as a product of hair bleaching. Relaxation treatment with sodium hydroxide increased the formation of dehydroalanine and dehydration products and moderately enhanced the levels of oxidation. Cysteine was the predominant modification site for both bleaching and alkali damage. CONCLUSION: This study validates the utility and power of redox proteomic-based approaches to characterizing hair modification. This offers potential application to a wide range of damage types, as well as evaluation of new damage mitigation and repair technologies.

Advantages of a high-throughput measure of hair fiber torsional properties.

While the tensile response of fibers of human hair is the most extensively studied mode of mechanical deformation, the properties of hair in different deformation modes remain of interest and can provide valuable insight into the effects of chemical treatments. Previously reported methods for the measurement of fibers in torsional deformation have inherent systematic errors, are low-throughput, and are operator-intensive. This paper presents a new method for the measurement of fiber torsional properties developed to reduce these errors and to improve the efficiency of the technique. This method was designed to be fully automated, requiring no operator input during an experiment, and affording higher sample throughput while improving the ease of use in variable climatic conditions. The new method is compared to a conventional torsional pendulum method for measuring fiber shear modulus, and an evaluation of experimental reproducibility is made using hair and nylon fibers. It was found that the new method provides absolute values for shear modulus similar to those of the pendulum technique, with reduced run-to-run variability between fibers, while enabling larger sample numbers to be explored in shorter times.

Pre-hospital prediction of adverse outcomes in patients with suspected COVID-19: Development, application and comparison of machine learning and deep learning methods.

BACKGROUND: COVID-19 infected millions of people and increased mortality worldwide. Patients with suspected COVID-19 utilised emergency medical services (EMS) and attended emergency departments, resulting in increased pressures and waiting times. Rapid and accurate decision-making is required to identify patients at high-risk of clinical deterioration following COVID-19 infection, whilst also avoiding unnecessary hospital admissions. Our study aimed to develop artificial intelligence models to predict adverse outcomes in suspected COVID-19 patients attended by EMS clinicians. METHOD: Linked ambulance service data were obtained for 7,549 adult patients with suspected COVID-19 infection attended by EMS clinicians in the Yorkshire and Humber region (England) from 18-03-2020 to 29-06-2020. We used support vector machines (SVM), extreme gradient boosting, artificial neural network (ANN) models, ensemble learning methods and logistic regression to predict the primary outcome (death or need for organ support within 30 days). Models were compared with two baselines: the decision made by EMS clinicians to convey patients to hospital, and the PRIEST clinical severity score. RESULTS: Of the 7,549 patients attended by EMS clinicians, 1,330 (17.6%) experienced the primary outcome. Machine Learning methods showed slight improvements in sensitivity over baseline results. Further improvements were obtained using stacking ensemble methods, the best geometric mean (GM) results were obtained using SVM and ANN as base learners when maximising sensitivity and specificity. CONCLUSIONS: These methods could potentially reduce the numbers of patients conveyed to hospital without a concomitant increase in adverse outcomes. Further work is required to test the models externally and develop an automated system for use in clinical settings.

Density functional theory based screening of ternary alkali-transition metal borohydrides: a computational material design project.

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M(1)); and 1 alkali, alkaline earth or 3d/4d transition metal atom (M(2)) plus two to five (BH(4))(-) groups, i.e., M(1)M(2)(BH(4))(2-5), using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M(1)(Al/Mn/Fe)(BH(4))(4), (Li/Na)Zn(BH(4))(3), and (Na/K)(Ni/Co)(BH(4))(3) alloys are found to be the most promising, followed by selected M(1)(Nb/Rh)(BH(4))(4) alloys.

The Effects of Simulated Wildland Firefighting Tasks on Core Temperature and Cognitive Function under Very Hot Conditions.

Background: The severity of wildland fires is increasing due to continually hotter and drier summers. Firefighters are required to make life altering decisions on the fireground, which requires analytical thinking, problem solving, and situational awareness. This study aimed to determine the effects of very hot (45°C; HOT) conditions on cognitive function following periods of simulated wildfire suppression work when compared to a temperate environment (18°C; CON). Methods: Ten male volunteer firefighters intermittently performed a simulated fireground task for 3 h in both the CON and HOT environments, with cognitive function tests (paired associates learning and spatial span) assessed at baseline (cog 1) and during the final 20-min of each hour (cog 2, 3, and 4). Reaction time was also assessed at cog 1 and cog 4. Pre- and post- body mass were recorded, and core and skin temperature were measured continuously throughout the protocol. Results: There were no differences between the CON and HOT trials for any of the cognitive assessments, regardless of complexity. While core temperature reached 38.7°C in the HOT (compared to only 37.5°C in the CON; p < 0.01), core temperature declined during the cognitive assessments in both conditions (at a rate of -0.15 ± 0.20°C·hr-1 and -0.63 ± 0.12°C·hr-1 in the HOT and CON trial respectively). Firefighters also maintained their pre-exercise body mass in both conditions, indicating euhydration. Conclusions: It is likely that this maintenance of euhydration and the relative drop in core temperature experienced between physical work bouts was responsible for the preservation of firefighters' cognitive function in the present study.

Cholesterol exchange between microsomal, mitochondrial and erythrocyte membranes and its enhancement by cytosol.

1. Cholesterol exchanges between isolated rat liver microsomes and mitochondria and between erythrocytes and microsomes or mitochondria during incubation in vitro. The exchange process is temperature dependent and is no accompanied by a net movement of sterol. 2. cholesterol exchange between the membranes was enhanced by the addition of 105 000 x g supernatant fraction (S105) from rat liver. The degree to which sterol exchange was enhanced was dependent on the amount of this supernatant fraction present in the incubation. 3. enhancement of sterol exchange was not observed with heated S105 fraction, but activity was retained after dialysis or aging at 10 degrees C; these results suggest the presence of a cholesterol-exchange protein in the cytosol from rat liver.

Cholesterol esterification by rat adrenal gland. Inhibition by local anesthetics in vitro.

Cholesterol esterification was studied in rat adrenal gland, adrenal homogenates and isolated adrenal microsomes. In whole gland and homogenates, the local anesthetic, lidocaine, inhibited the incorporation of [1-14C]oleate and [1-14C]oleoyl-CoA, respectively, into labeled cholesteryl esters in a dose-dependent manner. Inhibition of sterol esterification in the preparations reached 50% at about 2 mM. Various other local anesthetics (tetracaine, dibucaine and benzocaine) also inhibited sterol esterification in adrenal homogenates but were more potent than lidocaine; in each case, 90% inhibition occurred at anesthetic levels of 1 mM. Since sterol esterification in the adrenal gland is a function of microsomal acyl-CoA: cholesterol acyltransferase (EC 2.3.1.26), the enzyme was assayed in isolated adrenal microsomes in the presence of lidocaine while using [14C]oleoyl-CoA as a substrate for labeled cholesteryl ester formation. Inhibition of the enzymes by lidocaine was confirmed, with 50% inhibition occurring between 0.5 and 0.75 mM lidocaine. Lidocaine may be useful as a tool in studies on the regulation of adrenal sterol esterification.

Effect of local anesthetics on sterol biosynthesis and sterol esterification in rat liver in vitro.

Various local anesthetics were found to inhibit sterol esterification by acyl-CoA:cholesterol acyltransferase (EC 2.3.1.26) in the microsomal fraction from rat (and rabbit) liver and to inhibit sterologenesis in rat liver slices. The enzyme was assayed in isolated microsomes by following the incorporation of [1-14C]oleoyl-CoA into steryl esters; the order of inhibitory potency on the enzyme was dibucaine > benzocaine > tetracaine > lidocaine > procaine. In liver slices, the incorporation of labeled acetate and mevalonate into C27 sterols, digitonin-precipitable sterols, and squalene was inhibited in the order dibucaine > tetracaine > lidocaine. A comparison of incorportion patterns from labeled acetate and mevalonate suggest that inhibition of sterologenesis occurs at more than one post-mevalonate step in the pathway.

Proliferative and lipid metabolism response to balloon angioplasty in canine renal arteries.

The mechanisms responsible for reocclusion after percutaneous transluminal angioplasty are still poorly understood. The effects of angioplasty on arterial morphology, deoxyribonucleic acid (DNA) synthesis (3H-thymidine incorporation) and lipid metabolism (14C-oleate incorporation) were studied in renal arteries of 24 male mongrel dogs. Balloon-dilated (identified by Evans blue dye accumulation) and adjacent normal arterial segments were collected 90 min and 2, 5 and 14 days after the procedure. The immediate vascular response was endothelial cell denudation and platelet accumulation. Two weeks after angioplasty, healing of the luminal surface by "endothelial-like" cells, mild smooth muscle cell proliferation and an angiogenic response with capillary growth into the media were observed. DNA synthesis was increased in balloon-dilated segments at day 5 compared with adjacent nonballoon-dilated artery. This increase in DNA synthesis persisted in the 2 week postangioplasty segments. Additionally, angioplasty produced both quantitative and qualitative changes in arterial lipid synthesis. The most dramatic change was an increase in sterol esterification that was apparent as early as 90 min after angioplasty; the change persisted through day 5 but diminished toward baseline by day 14. Angioplasty-induced alterations of arterial metabolism parallel aspects of the atherogenic process and may be involved in the pathogenesis of postangioplasty reocclusion, particularly in the presence of additional risk factors, such as hyperlipemia.

Bak apoptotic pores involve a flexible C-terminal region and juxtaposition of the C-terminal transmembrane domains.

Bak and Bax mediate apoptotic cell death by oligomerizing and forming a pore in the mitochondrial outer membrane. Both proteins anchor to the outer membrane via a C-terminal transmembrane domain, although its topology within the apoptotic pore is not known. Cysteine-scanning mutagenesis and hydrophilic labeling confirmed that in healthy mitochondria the Bak α9 segment traverses the outer membrane, with 11 central residues shielded from labeling. After pore formation those residues remained shielded, indicating that α9 does not line a pore. Bak (and Bax) activation allowed linkage of α9 to neighboring α9 segments, identifying an α9:α9 interface in Bak (and Bax) oligomers. Although the linkage pattern along α9 indicated a preferred packing surface, there was no evidence of a dimerization motif. Rather, the interface was invoked in part by Bak conformation change and in part by BH3:groove dimerization. The α9:α9 interaction may constitute a secondary interface in Bak oligomers, as it could link BH3:groove dimers to high-order oligomers. Moreover, as high-order oligomers were generated when α9:α9 linkage in the membrane was combined with α6:α6 linkage on the membrane surface, the α6-α9 region in oligomerized Bak is flexible. These findings provide the first view of Bak carboxy terminus (C terminus) membrane topology within the apoptotic pore.

Induction of PG G/H synthase-2 in bovine myometrial cells by interferon-tau requires the activation of the p38 MAPK pathway.

PGs are regulators of a plethora of uterine functions during reproductive processes, including uterine contractility. In bovine uterus, the rate-limiting step in PG synthesis is catalyzed by the PG endoperoxide G/H synthase (PGHS) enzymes. It has previously been established that PGHS-2 isoform expression is affected by the ruminant-specific interferon (IFN)-tau in bovine endometrial cells. Here, we show that PGHS-2 mRNA and protein levels are induced by IFN-tau in primary cell cultures from bovine myometrium. Treatment with recombinant bovine IFN-tau induces the activation of the JAK-STAT and p38 MAPK pathways in bovine myometrial cells. Inhibition of the p38 pathway by the specific inhibitor SB203580 strongly decreases PGHS-2 mRNA and protein expression without affecting the phosphorylation and DNA-binding of transcription factors STAT-1 and STAT-2. The p38 pathway regulates PGHS-2 expression at the posttranscriptional level, because the presence of SB203580 results in the destabilization of IFN-tau-induced PGHS-2 mRNA. Taken together, these data demonstrate the ability of IFN-tau to induce the activation of the JAK-STAT pathway in a manner similar to other types of IFN (i.e. alpha, beta, and gamma) and to regulate PGHS-2 mRNA stability through the activation of the p38 pathway. These findings provide new insights into the physiological function of IFN-tau, in regard to regulation of specific genes associated with myometrial contractility.

Differential expression and regulation of connexin-43 and cell-cell coupling in myocytes from the circular and longitudinal layers of bovine myometrium.

The expression and localization of the gap junction protein connexin-43 (Cx-43) as well as functional coupling were studied in myocytes from the two layers of the bovine myometrium: the circular and the longitudinal layers. Intercellular communication (measured by Lucifer yellow dye transfer through gap junctions) was more intense in the circular than in the longitudinal layer of the bovine myometrium. The circular layer also exhibited a greater degree of punctuate immunofluorescence to Cx-43. Myocytes from the circular layer expressed more Cx-43 messenger RNA (mRNA; 2.38 +/- 0.46, Cx-43 over 18S RNA) than the longitudinal layer (1.46 +/- 0.48, Cx-43 over 18S RNA; P < 0.05). The modulation of Cx-43 expression by sex steroids in the two myometrial layers was tested using a pure steroidal antiestrogen, EM-139. In myocytes from the circular layer, the level of Cx-43 mRNA was decreased after treatment with 0.1 microM EM-139 (1.37 +/- 0.25, Cx-43 over 18S RNA) compared to that in untreated cells (2.38 +/- 0.46, Cx-43 over 18S RNA), representing a 40% inhibition. In parallel, cell-cell coupling and the amount of Cx-43 protein were also reduced after antiestrogen treatment. In contrast, treatment of cells from the longitudinal layer with the antiestrogen did not significantly affect the level of Cx-43 mRNA, protein, or cell-cell coupling. These data demonstrate that Cx-43 protein and mRNA are expressed and regulated differentially in myocytes from the circular and longitudinal layers of bovine myometrium. Furthermore, the circular myometrial layer may represent a preferential target for estrogen regulation of the biochemical and mechanical processes controlling contractility.

Carnitine metabolism in Macaca arctoides: the effects of dietary change and fasting on serum triglycerides, unesterified carnitine, esterified (acyl) carnitine, and beta-hydroxybutyrate.

Serum triglycerides and serum total, esterified, and free (unesterified) carnitine were measured in 21 male Macaca arctoides that were switched from a low fat (5.2% w/w), high carbohydrate diet to a high fat (15.9% w/w), low carbohydrate diet for 90 days and then returned to the original low fat diet for a subsequent 76-day period. Serum triglycerides and total carnitine levels fell significantly (p less than 0.05) during the initial 2 wk of feeding the high fat diet and the ratio of esterified/unesterified carnitine rose significantly (P less than 0.05) on the high fat diet. A return to the low fat diet reversed these changes; triglycerides rose significantly (p less than 0.05) within 3 days and the ratio of esterified/unesterified carnitine fell significantly (p less than 0.05) within 3 days and the ratio of esterified/unesterified carnitine fell significantly (p less than 0.05) during the same period. A return of total carnitine levels to those initially observed on the low fat diet was slower to develop. Fasting for 24 to 48 h resulted in increases of 65 to 75% in total serum carnitine. This increase reflected elevations of both the esterified and unesterified carnitine fractions but was largely attributable to increases in esterified carnitine which rose from 10 to 41 nmol/ml by 48 h while unesterified carnitine rose from 55 to 72 nmol/ml during the same period. In addition, the ratio of esterified/unesterified carnitine ratio rose from 0.183 +/- 0.023 to 0.583 +/- 0.069 (n = 8) with a 48-h fast and was significantly correlated with serum beta-hydroxybutyrate levels at both 24 and 48 h.