First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment

We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of 5.9 ton. During the (1.09±0.03)  ton yr exposure used for this search, the intrinsic ^{85}Kr and ^{222}Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3)  events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5 keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10^{-47}  cm^{2} for a WIMP mass of 28  GeV/c^{2} at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from multiply interacting massive particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This Letter places strong constraints on spin-independent interactions of dark matter particles with a mass between 1×10^{12} and 2×10^{17}  GeV/c^{2}. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross sections for dark matter particles with masses close to the Planck scale.

Search for New Physics in Electronic Recoil Data from XENONnT

We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3)  events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.

Material radiopurity control in the XENONnT experiment

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}∼17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn activity concentration in XENONnT is determined to be 4.2 (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{+0.5}_{-0.7}$$\end{document}-0.7+0.5) \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu $$\end{document}μBq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

222 Rn emanation measurements for the XENON1T experiment

The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222 Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222 Rn activity concentration of 10 μ Bq / kg in 3.2 t of xenon. The knowledge of the distribution of the 222 Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222 Rn activity concentration in XENON1T. The final 222 Rn activity concentration of ( 4.5 ± 0.1 ) μ Bq / kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.

Search for Coherent Elastic Scattering of Solar ^{8}B Neutrinos in the XENON1T Dark Matter Experiment

We report on a search for nuclear recoil signals from solar ^{8}B neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold from 2.6 to 1.6  keV. We develop a variety of novel techniques to limit the resulting increase in backgrounds near the threshold. No significant ^{8}B neutrinolike excess is found in an exposure of 0.6  t×y. For the first time, we use the nondetection of solar neutrinos to constrain the light yield from 1-2 keV nuclear recoils in liquid xenon, as well as nonstandard neutrino-quark interactions. Finally, we improve upon world-leading constraints on dark matter-nucleus interactions for dark matter masses between 3 and 11  GeV c^{-2} by as much as an order of magnitude.

Preparation and in vitro evaluation of PLA/biphasic calcium phosphate filaments used for fused deposition modelling of scaffolds

Ceramic materials such as calcium phosphates (CaPs) with a composition similar to the mineral phase of bones and polymeric polylactic acid (PLA) are potential candidates for the manufacturing of scaffolds to act as bone substitutes and for tissue engineering applications, due to their bioresorbability and biocompatibility. Variables such as porosity, topography, morphology, and mechanical properties play an essential role in the scaffolds response. In this paper, a polymer/ceramic composite filament of 1.7 mm in diameter based on PLA and biphasic calcium phosphates (BCPs) was obtained by hot-melt extrusion in a single screw extruder. The particles of BCP were obtained by solution-combustion synthesis, and the PLA used was commercial grade. The BCPs ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopy (TEM), and Brunauer, Emmett, and Teller (BET). It was possible to confirm that the main inorganic phases were hydroxyapatite (HAP) and tricalcium phosphate (TCP) with grain sizes below 100 nm and with high porosity. The Filaments obtained are a bit fragile but were able to be used in fused deposition modelling (FDM) using low-cost commercial printers. The filaments were characterized by SEM and energy dispersive X-ray (EDX). The in-vitro tests of filaments showed deposition of apatite phases on their surface, non-cytotoxic behavior, adequate cell proliferation and cell adhesion.

Light Dark Matter Search with Ionization Signals in XENON1T

We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4  keV_{ee}, we observe <1  event/(tonne day keV_{ee}), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses m_{χ} within 3-6  GeV/c^{2}, DM-electron scattering for m_{χ}>30  MeV/c^{2}, and absorption of dark photons and axionlike particles for m_{χ} within 0.186-1  keV/c^{2}.

Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T

Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above ∼5  GeV/c^{2}, but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about 85  MeV/c^{2} by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.

Effect of age and severity of cognitive dysfunction on two simple tasks in pet dogs

Dogs exhibit age-dependent losses in learning and memory as well as a progressive accumulation of neuropathology that parallels that observed in normal human aging and early Alzheimer's disease. These deficits have been extensively studied using a number of standard cognitive tasks in the laboratory; however, appropriate tools for their assessment in veterinary clinics are still lacking. The aim of this study was to evaluate the effect of age and the severity of cognitive dysfunction syndrome (CDS) on two simple tests conducted in a clinical setting. A food searching (FS) task and a problem-solving (PS) task were administered to young (1-4 years, n=9), middle-aged (5-8 years, n=10), cognitively unimpaired aged (≥9 years, n=31), and cognitively impaired aged (≥ 9 years, n=37) dogs. Cognitive status was classified using an owner-based questionnaire, and in the impaired group, dogs were categorized as having either mild or severe CDS. During the FS task, younger dogs (<9 years) were able to locate the food more quickly and with more success than the aged groups (≥9 years). Dogs with severe CDS exhibited poorer performance than those with mild CDS or their healthy counterparts. In the PS task, younger dogs performed better than the aged dogs in obtaining food, but there were no differences related to CDS severity. The FS task might help to better characterize cognitively affected dogs in the clinical setting than the PS task. These and similar tasks require further investigations in the field.

Effect of age and severity of cognitive dysfunction on spontaneous activity in pet dogs - part 1: locomotor and exploratory behaviour

Age-related cognitive dysfunction syndrome (CDS) has been reported in dogs and it is considered a natural model for Alzheimer's disease in humans. Changes in spontaneous activity (including locomotor and exploratory behaviour) and social responsiveness have been related to the age and cognitive status of kennel-reared Beagle dogs. The aim of this study was to assess the influence of age and severity of CDS on locomotor and exploratory behaviour of privately owned dogs. This is the first part of a two-part report on spontaneous activity in pet dogs. An open-field (OF) test and a curiosity test were administered at baseline and 6 months later to young (1-4 years, n=9), middle-aged (5-8 years, n=9), cognitively unimpaired aged (≥ 9 years, n=31), and cognitively impaired aged ( ≥ 9 years, n=36) animals. Classification of cognitive status was carried out using an owner-based observational questionnaire, and in the cognitively impaired group, the dogs were categorised as having either mild or severe cognitive impairment. Dogs were recorded during sessions in the testing room and the video-recordings were subsequently analysed. The severity of CDS (but not age) influenced locomotion and exploratory behaviour so that the more severe the impairment, the higher the locomotor activity and frequency of corner-directed (aimless) behaviours, and the lower the frequency of door-aimed activities. Curiosity directed toward novel stimuli exhibited an age-dependent decline although severely affected animals displayed more sniffing episodes directed towards the objects. OF activity did not change after 6 months. Testing aged pet dogs for spontaneous behaviour might help to better characterise cognitively affected individuals.

Effect of age and severity of cognitive dysfunction on spontaneous activity in pet dogs - part 2: social responsiveness

Changes in social interactions with owners and other dogs are frequently observed in dogs with cognitive dysfunction syndrome (CDS). The aim of this work was to assess the effect of age and severity of CDS on social responsiveness. This is the second part of a 2-part report on spontaneous activity in pet dogs. A human interaction test and a mirror test were administered at baseline and 6 months later to assess social responses to humans and conspecifics, respectively, to four groups of privately-owned dogs: young (n=9), middle-aged (n=9), cognitively unimpaired aged (n=31), and cognitively impaired aged (n=36). The severity of cognitive impairment was considered in the last group and dogs were categorised as having either mild or severe CDS. The influence of the person and the mirror on locomotion and exploratory behaviour was also studied. Dogs were recorded in a testing room and the video recordings were subsequently analysed. Young dogs displayed more interactions involving physical contact with a person. Young and middle-aged dogs showed more vocalisations in response to social isolation. In contrast, aged animals spent more time in front of the mirror. Changes in social responsiveness associated with severe CDS included decreased response to social isolation and human interaction and increased time in front of the mirror, suggesting a deficit in habituation. Testing of spontaneous activity might help to characterise CDS in aged dogs, a condition increasingly diagnosed in veterinary clinics and a potentially useful natural model of Alzheimer's disease in humans.

Effect of fluoxetine on blood concentrations of serotonin, cortisol and dehydroepiandrosterone in canine aggression

Canine aggression directed towards people is the most frequent reason for referral to behaviour practices. The serotonergic system and the hypothalamic-pituitary-adrenal (HPA) axis are believed to play an important role in controlling aggression. The selective serotonin reuptake inhibitor fluoxetine is the most commonly used drug in canine aggression. The aim of the present study was to assess the effect of a 30-day-long fluoxetine treatment on the peripheral serotonergic system and the HPA axis in canine aggression. To this end, the concentrations of serum serotonin (5-HT) and plasma cortisol and dehydroepiandrosterone (DHEA) were analysed in a group of aggressive (n = 22) and nonaggressive dogs (n = 9) during pre- (day 0) and posttreatment (day 30) conditions. Treatment caused a significant decrease in 5-HT concentrations (46% in the aggressive group and 32% in the control group). There was a trend towards a rise of DHEA/cortisol ratio values after treatment both in the aggressive and the control group. The determination of blood 5-HT and the DHEA/cortisol ratio could have important clinical applications in the future for deciding which animals might benefit from a given treatment as well as for monitoring the response. Further large-scale studies with this aim should be carried out to obtain sound conclusions.

Does breed affect nursing and reproductive behaviour in beef cattle?

This experiment was designed to assess the role of genetic differences in nursing behaviour and the resumption of post-partum ovarian cyclicity of beef cows with different types of calf management. Twenty-four multiparous winter-calving cows, 12 Parda de Montaña (PA) and 12 Pirenaica (PI), were randomly assigned to once-daily restricted nursing during 30 min (RESTR) or ad libitum nursing (ADLIB). Cow-calf behaviour was recorded at weeks 3, 8 and 13 of lactation. Results were compared within suckling system. Twice-weekly blood samples were drawn throughout lactation to analyse progesterone as an indicator of ovulation. Within each type of calf management, both breeds nursed their calves for a similar amount of time (23.0 and 57.2 min in PA vs. 25.9 and 59.0 min in PI, when nursing once daily or ad libitum, respectively; P > 0.10). Furthermore, ovarian cyclicity was initiated at a similar time after calving between breeds (70 vs. 73 d in PA and PI, respectively), although it was shorter in RESTR than in ADLIB (54 vs. 89 d; P < 0.001). Key words: Beef cattle, calf management, restricted nursing, post-partum anoestrus

Luteinizing hormone and growth hormone secretion in early lactating Spanish beef cows

The episodic release of luteinizing hormone (LH) and growth hormones (GH) was studied in three suckling regimens and two breeds of Spanish suckled cows. Parda de Montaña (PA) cows (n = 21) were assigned to once-daily, twice-daily or ad libitum (ADLIB) suckling. Pirenaica (PI) cows (n = 7) were used to evaluate the breed effect in twice-daily suckling. Coccygeal blood samples were collected twice weekly during lactation to determine the interval from calving to first ovulation through peripheral progesterone. On day 32 ± 3 post-partum, jugular blood samples were drawn at 15 min intervals during 8 h to analyse circulating LH and GH. The interval to first ovulation was greater in PA cows suckling ADLIB than in restricted suckling treatment (RESTR1), whereas in RESTR2 it did not differ from the other two treatments. There were no differences between PA and PI cows in the interval to first ovulation. RESTR1 cows showed a tendency to have shorter LH peak widths than ADLIB cows. PA cows showed a tendency to have longer LH peak widths than their PI counterparts. There were no differences across treatments or breeds in any of the GH measures of secretion. The LH release was more affected by breed than by suckling frequency, whereas that of GH was not influenced by any of these parameters. The variables that best allowed discrimination between ADLIB and restricted nursing systems were the interval to post-partum first ovulation, LH peak number and the mean GH concentration.

Metabolic and luteal function in winter-calving Spanish beef cows as affected by calf management and breed

This experiment aimed at evaluating the effect of calf management and breed on the metabolic and luteal function of post-partum beef cows fed at maintenance. Fifty multiparous cows, 22 Parda de Montaña (PA) and 28 Pirenaica (PI), were assigned to either suckling once-daily for 30 min (RESTR) or ad libitum (ADLIB) from the day after calving. Blood samples were collected to analyse metabolites [non-esterified fatty acids (NEFA), beta-hydroxybutyrate, total protein and urea)], insulin-like growth factor-I (IGF-I) and progesterone (P4) at different intervals. Cows from RESTR maintained their live-weight (LW) over the first 3 months post-partum, whereas ADLIB cows lost nearly 4% LW. Both genotypes showed similar LW gains during this period (p > 0.10). Calf daily gains were lower in RESTR than in ADLIB treatment (p < 0.05), but similar across breeds (p > 0.10). Milk and lactose production were lower in RESTR cows than in ADLIB (p < 0.05). Milk and protein yield were greater in PA than in PI breed (p < 0.05). Serum NEFA, total protein and urea were higher in PI cows suckling ADLIB than in the rest (p < 0.05). Cows from PI breed had greater NEFA values than PA ones on the first week post-partum (p < 0.001). Circulating IGF-I was not affected by suckling frequency, breed nor their interaction (p > 0.10). Suckling frequency, but not breed, affected the interval from calving to first ovulation (p < 0.001), being shorter in RESTR than in ADLIB cows. In conclusion, the ad libitum suckling practice improved cow milk yield and offspring gain compared to once-daily suckling for 30 min from the day after calving, at the expense of impairing the onset of cyclicity. The effect of calf management was confounded with breed on the studied blood biochemical constituents, but any of these metabolites influenced the role of endocrine IGF-I in these genotypes.

Prevalence and risk factors of behavioural changes associated with age-related cognitive impairment in geriatric dogs

OBJECTIVES

The aim of this study was to describe the prevalence and severity of behavioural changes associated with age and their relationship to risk factors such as sex, reproductive status, bodyweight and age.

METHODS

A cross-sectional study design was chosen. A total of 325 geriatric dogs were included. Owners of dogs older than nine years were interviewed by a veterinary behaviourist. Structured phone interviews were used to gather information about four behavioural categories related to cognitive impairment: sleep/wake cycles, social interaction, learning and house training and signs of disorientation.

RESULTS

Signs of cognitive impairment showed a prevalence of 22.5 per cent in geriatric dogs. Sex and age emerged as significant predictor variables. Females and neutered dogs were significantly more affected than males and entire dogs, respectively. Prevalence and severity increased with age. Although weight was not a statistically significant predictor variable, smaller animals had greater odds of showing age-related cognitive impairment. The most impaired behavioural categories were social interaction and house training.

CLINICAL SIGNIFICANCE

Age-related behavioural changes should be considered by practicing veterinarians because of their relative high prevalence among geriatric dogs, especially in females.

A genetic fusion GDNF-C fragment of tetanus toxin prolongs survival in a symptomatic mouse ALS model

PURPOSE

Amyotrophic Lateral Sclerosis (ALS) is a paralyzing disorder that kills individuals within three to five years of onset without any possibility for effective treatment. One proposed therapy has been the use of neurotrophic factors to inhibit the apoptosis of motorneurones. At the present, one way to deliver neurotrophic factors after intramuscular injection to the motor neurones is through the use of adenoviral vectors. An alternative strategy is the use of the atoxic C fragment of tetanus toxin (TTC) as a neurotrophic factor carrier for motorneurones.

METHODS

We have produced the recombinant protein fusion Glial Derived Neurotrophic Factor and C fragment of tetanus toxin (GDNF-TTC) and we have tested its antiapoptotic activity in degeneration culture cells and in the symptomatic SOD;{G93A} transgenic animal model for ALS.

RESULTS

We demonstrated that GDNF-TTC induces the neuronal survival Akt kinase pathway in mouse cortical culture neurons and~maintains its antiapoptotic neuronal activity in Neuro2A cells. Moreover, we have found that genetic fusion is able to increase survival by 9 days and improves life quality in symptomatic ALS animal models.

CONCLUSION

These results suggest that recombinant GDNF-TTC fusion protein intramuscular injections provide a potential therapy for ALS treatment.

[Fiber-optic bronchoscopic biopsy of bronchial smooth muscle. Efficacy of the technique in individuals with normal lung function and patients with COPD]

BACKGROUND AND OBJECTIVES

The epithelium and airway smooth muscles of patients with chronic obstructive pulmonary disease (COPD) or bronchial asthma undergo certain structural changes that are probably related to increased expression of inflammatory molecules and cell growth factors. Studying the relation between disease and changes in bronchial smooth muscle is difficult if investigation is restricted to samples from autopsies or thoracotomies. This study was designed to evaluate the probability of obtaining bronchial smooth muscle by endoscopic bronchial biopsy in patients with COPD and from individuals with normal lung function, the relation of disease to bronchial epithelial histology, and the potential usefulness of studying airway muscle remodeling events.

METHODS

Forty-two patients undergoing diagnostic fiberoptic bronchoscopy were enrolled. Bronchial biopsies were taken systematically from the lobar and segmental dividing ridges. The epithelial structure was analyzed by conventional histology. The smooth muscle was identified by immunohistochemistry (anti-desmin antibody assay) and Western-blot analysis (anti-desmin, actin and myosin antibodies).

RESULTS

Sixty-nine percent of the biopsies contained bronchial smooth muscle. The probability of obtaining smooth muscle was higher in segmental than in lobar biopsies (72 vs 30%, p < 0.05). This probability was unrelated to the presence of COPD or to signs of epithelial inflammation. The fragments allowed us to use electrophoresis to identify protein structures (myosin, actin, desmin) involved in muscle remodeling processes.

CONCLUSIONS

Endoscopic biopsy of the bronchi allows us to obtain bronchial smooth muscle samples in a large percentage of patients, particularly when performed on segmental bronchi. The technique may be useful for future studies examining the processes of airway smooth muscle remodeling.

[Interleukin 10 and tumor necrosis factor alpha gene expression in respiratory and peripheral muscles. Relation to sarcolemmal damage]

BACKGROUND

Tumor necrosis factor alpha (TNF-alpha) has been implicated in loss of muscle mass in chronic obstructive pulmonary disease and other consumptive processes. TNF-alpha production would be related to inflammation arising from pulmonary disease itself or, alternatively, from smoking, and would be carried to the muscle through the blood stream. However, it has also been suggested that TNF-alpha may be expressed directly in muscle tissue. Regardless the site of production of TNF-alpha, its relation to subsequent muscle damage is unclear.

OBJECTIVE

We studied the expression of TNF-alpha and an interleukin inhibitor of its production (IL-10) in the main respiratory muscles and a peripheral muscle in the dog.

METHOD

Nine young, male Beagle dogs were included. From all animals we obtained a biopsy of the diaphragm (Dph) and external intercostal (ExtI) muscles and a leg muscle (internal vastus of the quadriceps, IntV). TNF-alpha and IL-10 gene expressions were measured through the analysis of messenger RNA levels, using reverse transcription and polymerase chain reaction. We also assessed sarcolemmal damage using intracellular fibronectin detection (immunohistochemistry).

RESULTS

The expression of both cytokines showed wide interindividual variability. On the one hand, TNF-alpha (was very low in Dph and ExtI (0.02 0.03 and 0.05 0.06 a.u., respectively), but relatively high in the IntV (0.14 0.08 a.u.). IL-10 expression, on the other hand was low in the Dph (0.06 0.05 a.u.) and slightly higher in the ExtI (2.7 1.9 a.u., p < 0.01) and IntV (1.6 1.7 a.u.). Sarcolemmal damage was minimal in all three muscles and was related to TNF-alpha expression in the peripheral muscle (r = 0.682, p < 0.05).

CONCLUSIONS

1) TNF-alpha and IL-10 appear to be constitutively expressed within the skeletal muscle in dogs. 2) Basal TNF-alpha expression is lower in respiratory muscles than in peripheral muscles. 3) The expression in the latter is related to membrane damage.

Procion orange tracer dye technique vs. identification of intrafibrillar fibronectin in the assessment of sarcolemmal damage

BACKGROUND

The use of Procion orange dye (POD) is one of the most widely accepted techniques to assess sarcolemmal damage. This phenomenon has been related to functional adaptation in skeletal muscles. The POD method includes intravenous injection of this colorant in vivo, enabling its identification inside those fibres with membrane leaks (fluorescence). However, the safety of the use of POD has not been proven.

AIM

This study was designed to compare POD with a safer alternative, involving the identification of intracellular fibronectin using specific antibodies.

METHOD

Eight Swiss mice were submitted to electrical stimulation of the lower limbs at different frequencies (10-80 Hz). Subsequently, the POD solution was infused, and samples from the vastus medialis muscle were obtained 24 h later. Samples were processed and serial sections were analysed using immunohistochemistry (monoclonal antibodies against fibronectin) and epifluorescence microscopy.

RESULTS

Ninety-eight per cent of the fibres were equally classified by both techniques, which in addition showed good correlation (percentages of damaged fibres, r = 0.998, P < 0.001) and concordance (R1 = 0.82) in quantitative terms.

CONCLUSIONS

Although the two techniques compared here are based on different principles, both are comparable in assessing sarcolemmal damage. This would facilitate comparisons between human and experimental studies. In addition, the fibronectin technique appears to be a suitable alternative for long-term studies including repeated biopsies.

[Basic structure of respiratory and peripheral muscles in the beagle dog]

BACKGROUND

The dog is one of the most widely used animals in studies of respiratory physiopathology, mainly because of its physiological characteristics. However, ethical and legal constraints are placed on the use of some species in our context.

OBJECTIVE

We studied the underlying structural features of respiratory and peripheral muscles in the beagle dog in order to suggest reference values for future studies.

METHOD

Fourteen young beagles were selected. Samples were taken from the costal diaphragm (DFG), external intercostal (EI) and vastus medialis (VM) muscles. We analyzed fiber percentages and sizes (immunohistochemistry, using myosin heavy chain [MyHC (monoclonal antibodies), percentages and absolute number of MyHC isoforms (electrophoresis and ELISA), and level of membrane damage (immunohistochemistry, using anti-fibronectin monoclonal antibodies).

RESULTS

In the EI muscle, type I fibers were larger (by 20%) than type II fibers. Fibers resistant to fatigue (type I) predominated greatly over fast contraction fibers (type II) in all three muscles analyzed (DFG 57% 11% vs. 45% 12%; EI 58% 5% vs. 43% 5%; and VM 70% 8% vs. 34% 7 %). Few hybrid fibers (co-expression of fast and slow MyHC) were found and their percentages were similar in all three muscles. The absolute expression of MyHC was greater in the VM than in the respiratory muscles, with a relative predominance of the MyHC I isoform in the DFG and VM muscles and a similar tendency in the EI muscle. Membrane damage was very slight in all three muscles.

CONCLUSIONS

The phenotype characteristics of respiratory and peripheral muscles in the beagle correspond to what we would expect functionally for a breed initially selected for hunting, with minimal lesions under normal circumstances, a predominance of fibers and proteins that are resistant to fatigue, and larger fibers in the EI, a muscle that plays a role in respiration in dogs.

[Obtaining samples of the human diaphragm during upper laparotomy. A structural analysis]

The diaphragm seems to undergo adaptive structural change in chronic obstructive pulmonary disease. The possibility of obtaining muscle specimens is limited, however, particularly when respiratory function is severely affected.

OBJECTIVE

To assess the viability of a new technique for obtaining diaphragm muscle samples appropriate for structural assessment even from patients with severe functional change, and to study the size of fibers in relation to severity of disease.

METHODS

Fifteen muscle specimens were obtained from patients (aged 57 +/- 15 years) by abdominal laparotomy. All had undergone full lung function testing. Muscle samples were taken during surgery using a new technique involving formation of a tobacco pouch with dome biopsy. The method had been previously validated in animal models. Later, the biopsies were processed to evaluate fiber proportions and sizes (ATPase dyes at different levels of pH).

RESULTS

The 15 patients had a wide range of lung function results (FEV1 22-120% ref); 4 were severely affected (FEV1 < or = 50% ref). Nutritional status was normal in all cases; FEV1/FVC was 67 +/- 13%, RV was 134 +/- 55% ref, maximal mouth pressure (PImmax) was -75 +/- 27 cmH2O, transdiaphragmatic pressure (PIdimax) was 96 +/- 26 cmH2O, DLCO was 87 +/- 26% ref and PaO2 was 89 +/- 14 mmHg. We were able to obtain specimens valid for structural analysis from all patients with no complications. Light type I fibers predominated (54 +/- 9%) and size was normal overall (57 +/- 9 microns minimum diameter [Dm] atrophy index 195 +/- 243, and hypertrophy index 66 +/- 78), with no differences between the two fiber subtypes (Dm 58 +/- 8 microns for type I and 61 +/- 8 microns for type II). Overall size correlated inversely with static volumes (e.g. Dm with RV, r = -0.729, p < 0.01).

CONCLUSIONS

The laparoscopic technique described is simple and safe for use in humans to obtain diaphragm muscle specimens that are valid for morphometric analysis, allowing us to enlarge the range of subjects that can be enrolled for this type of study. The fiber muscles studied are smaller when functional involvement is greater in chronic obstructive pulmonary disease.

Enzymuria as an index of renal damage in canine leishmaniasis

Urinary enzyme activities of alanine aminopeptidase, gamma-glutamyl transpeptidase, alkaline phosphatase, N-acetyl-beta-D-glucosaminidase and beta-glucuronidase were determined in 15 dogs with leishmaniasis and in a group of eight normal dogs. Serum creatinine and blood urea nitrogen concentrations were also measured and renal histology was examined. All the affected dogs had renal lesions. However, no significant differences in blood urea nitrogen and creatinine concentrations were found between the control group and the affected group. The urinary enzyme activities of gamma-glutamyl transpeptidase (P < 0.01), N-acetyl-beta-D-glucosaminidase (P < 0.01) and beta-glucuronidase (P < 0.05) were significantly higher in the affected dogs. Urinary enzymes therefore seem to be a more sensitive and reliable test for assessing early renal damage in canine leishmaniasis than serum creatinine or blood urea nitrogen concentrations.

In vitro HIV1 infection of human cervical tissue

Heterosexual intercourse is the major mode of transmission of the human immunodeficiency virus (HIV) worldwide. Heterosexual transmission of HIV is particularly important in Africa and is increasing in the developed world. The mechanism of HIV infection of the female genital tract with HIV and subsequent events leading to clinical infection are not fully understood. In particular, the primary cellular targets of HIV infection in the female genital tract have not been determined. We have established an in vitro model for studying HIV infection of the human adult cervix by HIV. Human cervical mucosal explants were briefly exposed to HIV strains of different tropism and maintained in organ culture for 7 days. HIV infection detected by immunohistochemistry and in situ hybridization was only observed in cervical explants exposed to macrophage tropic strain HIV1Ba-L. HIV-infected cells were located in submucosa and had the morphology and distribution of macrophages. While CD4+/CD3+ T cells were still present at day 7 in the organ culture tissue, no infection of cervical explants was seen with T cell tropic strains even in the presence of phytohaemagglutinin and IL2. This model system will enable study of the dynamics of HIV infection of the human cervix and analysis of possible prophylactic or therapeutic strategies.