bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Exposure to High Temperature and Feeding Level on Regional Blood Flow and Oxidative Capacity of Tissues in Piglets
Authors: Collin A. , Lebreton Y. , Fillaut M. , Vincent A. , Thomas F. , Herpin P.
Published: February 2003

To determine to what extent exposure to high ambient temperature and feeding level affect tissue energy metabolism in piglets, regional blood flow and oxidative capacity of tissues were evaluated in sixteen 21.8 ± 2.8 kg pigs. At 5 weeks of age, littermates were divided into three groups and acclimated to the treatment for 25 days. One group was reared at 33°C and fed ad libitum (33AL, n= 6) while the other two groups were maintained at 23°C and either pair‐fed on the basis of the food consumption of their 33AL littermates (23PF, n= 5), or fed ad libitum (23AL, n= 5). Regional blood flow was determined in conscious pigs by injection of coloured microspheres, which were recovered in different tissues after slaughter. Activities of cytochrome oxidase and cytochrome aa3 content were measured in tissue homogenates of heart, longissimus dorsi and rhomboideus muscles, liver and small intestine. There was decreased blood flow to internal adipose tissue (42%) and increased blood flow to peripheral tissues (skin, 44%) and tissues implicated in respiratory evaporative heat loss (diaphragm, 45%, lungs, 59%) at 33°C compared to 23°C, which can be viewed as an effective mechanism for increasing heat loss at high temperature. In addition, the concomitant decrease in blood flow (49%) and slight reduction of oxidative capacities in both muscles at 33°C might contribute to the reduction in thermogenesis, but these effects were also observed when the feeding level was reduced at thermal neutrality (23PF group). In the viscera (intestine, liver), blood flow was decreased in the two groups on a restricted food intake (about 50% of 23AL), independently of environmental temperature. The results suggest that most of the mechanisms associated with the reduction in energy expenditure during warm acclimation are related to the adaptive reduction in food intake.
Effects of T‐Lymphocyte‐Dependent and ‐Independent Immunity on Cholinergic Enzyme Activity in Mouse Lacrimal Gland
Authors: Sinha Kakali , Dannelly H. Kathleen , Ghosh Swapan K.
Published: February 2003

The nature of the immune response following ocular immunization with a protein and a polysaccharide and the effects such immunization have on the activities of cholinergic enzymes in the lacrimal glands of BALB/c mice were examined. Lacrimal glands are highly innervated by sympathetic and parasympathetic nerve fibres and are involved in mucosal immunity and therefore are excellent sites to study neuro‐immune interactions. In this report, a T‐lymphocyte‐dependent protein antigen, keyhole limpet haemocyanin (KLH) and a T‐lymphocyte‐independent polysaccharide antigen, dextran (DEX) were administered topically to the eyes or intraperitoneally injected. Both routes of immunization produced a strong serum antibody response when KLH was the antigen. DEX, however, evoked a serum antibody response only after intraperitoneal administration. Eosin‐haematoxylin staining indicated no histological abnormality or inflammatory changes in any immunized lacrimal glands, but immuno‐staining revealed that only in the KLH‐treated tissues were IgG‐producing plasma cells discernible. Furthermore, KLH‐specific antibody was also detectable using an immuno‐blot assay in lacrimal glands. Polymerase chain reaction analysis with cytokine‐specific primers revealed induction of interleukin‐4 (lL‐4) in KLH‐treated lacrimal glands, but not in DEX or unimmunized tissues. Thus, the nature of the antigen seems important in the induction of the immune response in lacrimal glands. To delineate the effects that immunogenic differences might have on the activities of the cholinergic enzymes, choline acetyl‐transferase (ChAT) and acetylcholinesterase (AChE) were assayed using radiolabelled substrates and measuring labelled products. Both ChAT and AChE activities were influenced following KLH immunization, while DEX had only transient effects on ChAT. This is possibly due to the fact that KLH, a protein antigen, is the effective inducer of the specific immune response in the lacrimal gland, while DEX is not.
The Independence of Lung Liquid Absorption in Postnatal Sheep on Pulmonary Blood Flow, Blood Gases or Perfusion Pressure
Authors: Junor R. W. J. , Benjamin A. R. , Alexandrou D. , Walters D. V.
Published: February 2003

This study was performed to determine whether the absorption of liquid from the lungs of postnatal sheep is dependent on pulmonary perfusion pressure, blood gases or blood flow. Relationships between perfusion pressure, rate of lung liquid absorption and perfusate PO2, PCO2 and pH were examined by linear regression analysis from in situ perfused lungs from sheep aged 6 weeks to 6 months. The airspaces of the lungs were filled with liquid containing an impermeant tracer, to allow measurement of the rate of liquid absorption. There was no significant relationship between the rate of lung liquid absorption and pulmonary blood flow (n= 36, r= ‐0.01, P > 0.1), pulmonary perfusion pressure (n= 36, r= 0.28, P > 0.05) or perfusate PO2, PCO2 or pH. No significant relationships were found between pulmonary blood flow and perfusate PO2, PCO2 or pH. There was no evidence to suggest that the absorption of liquid from the lungs of postnatal sheep is dependent on pulmonary blood flow, blood gases or perfusion pressure, within the limits studied, indicating that lung liquid absorption is dependent on the pulmonary epithelium and not on the pulmonary vasculature. The findings that lung liquid absorption continues in hypoxic environments and despite severe reductions in blood flow may be relevant to the field of transplant surgery.
Impact of the Timing of Indomethacin Treatment in a Model of Synchronized Bone Remodelling in Rats
Authors: Guez Dominique , Lesclous Philippe , Baroukh Brigitte , Saffar Jean‐Louis
Published: February 2003

Prostaglandins (PGs) promote both bone resorption and formation in vitro and in vivo. In a synchronised model of bone remodelling, indomethacin, an inhibitor of PG synthesis, given from the start of the sequence, transiently impaired bone resorption. In this study we further explored the involvement of PGs in this model by treating rats with indomethacin (7.5 mg kg−1 day−1) for 6 days from the peak of resorption (day 4 after activation in this model) or during reversal (day 6 after activation). In rats treated from day 4, the resorption surface (Oc.S/BS) and the number of osteoclasts (N.Oc/BPm) were higher on day 10 (+69%, P < 0.01, and +60%, P < 0.02 compared with controls, respectively); no effect on cell resorptive activity was observed. The bone formation surface (OS/BS) was reduced (‐50%, P < 0.01). The inactive surface (In/BS) was not modified. In rats treated from day 6, the Oc.S/BS was also higher than in controls (P < 0.02), as was the N.Oc/BPm (P < 0.05). Osteoclast activity appeared to be increased, as the osteoclast‐bone interface was larger (P < 0.02), but the mean lacuna area was reduced (‐23%, P < 0.05). Bone formation was also strongly affected: the OS/BS was decreased (‐66%, P < 0.01), as was the osteoid seam thickness (‐24%, P < 0.05). The In/BS was increased 1.5‐fold (P < 0.05). These data indicate that PGs intervene at various stages of this remodelling sequence, as both resorption and formation were affected by indomethacin. Although resorption resumed in the two treatment groups despite treatment continuation, the timing of treatment was clearly important. Only inhibition of PG synthesis at the peak of resorption delayed all phases of the remodelling sequence. In contrast, inhibition during the reversal phase prevented activation of a significant part of the bone surface usually involved at this stage of remodelling; this treatment schedule reduced the resorptive capacity of the system, and depressed osteoblast activity.
The Role of Cholinergic and Peptidergic Pathways in the Regulation of Pancreatic Exocrine Function During Postnatal Development in Pigs
Authors: Lesniewska V. , Gregard A. , Weström B. , Hedemann M. S. , Lærke H. N. , Kruszewska D. , Pierzynowski S. G.
Published: February 2003

The aim of this study was to investigate the role of the parasympathetic (cholinergic and peptidergic) nervous system in the regulation of exocrine pancreas function in piglets during their early postnatal development. The cholinergic and peptidergic regulatory pathways of exocrine pancreatic function were tested by the specific muscarinic receptor blocker 4‐diphenylacetoxy‐N‐methylpiperidine‐methiodide (4‐DAMP) and bombesin, respectively. At the age of 2 weeks, piglets were surgically fitted with a chronic pancreatic duct catheter, a duodenal re‐entrant cannula and a jugular vein catheter. The experiments comprised a pre‐weaning period, and a post‐weaning period that commenced at the beginning of the 5th week of age. Intravenous infusion of 4‐DAMP (100 pmol kg−1 h−1) reduced the outflow of pancreatic juice, the output of total protein and the activity of trypsin, chymotrypsin, carboxyl ester hydrolase and amylase during preprandial and postprandial pancreatic secretion, in both the pre‐ and post‐weaning periods. However, the inhibitory effect of 4‐DAMP during postprandial secretion was significantly greater (P < 0.05) in suckling piglets. The infusion of bombesin (10, 100 and 1000 pmol kg−1 h−1) stimulated exocrine pancreatic secretion in a dose‐dependent manner during both the pre‐ and post‐weaning periods. However, the stimulatory effect of 1000 pmol kg−1 h−1 bombesin on total protein output and the activities of trypsin, chymotrypsin and amylase were significantly higher (P < 0.05) in suckling piglets. In summary, our study showed that cholinergic and peptidergic mechanisms are involved in the regulation of exocrine pancreas function in piglets in both the pre‐ and post‐weaning stages. 4‐DAMP had a greater inhibitory effect on exocrine pancreatic secretion in piglets during the pre‐weaning period. Thus, these observations suggest that the parasympathetic nervous system plays a dominant role in the functioning of the exocrine pancreas at this time. The action of bombesin suggests that it is a potent secretagogue for the exocrine pancreas in pigs during their postnatal development.
Interaction of Diet and Training on Endurance Performance in Rats
Authors: Sam Lee Jong , Bruce Clinton R. , Spriet Lawrence L. , Hawley John A.
Published: February 2003

We determined the interaction of diet and training on metabolic adaptations in skeletal muscle and liver, and the consequences of these adaptations for endurance. Eighty rats performed a baseline treadmill run to exhaustion at 16 m min−1 (RUN1) and were then divided into two groups and given one of two diets: high carbohydrate (CHO) or high fat (FAT). Each dietary group was then divided into one of four subgroups: sedentary control that performed no training (NT); low‐intensity running (8 m min−1; LOW) and two groups who trained at their maximal voluntary running speed without electrical stimulation (28 m min−1; VMAX). Training volume was identical for LOW and VMAX (1000 m session−1) and animals ran 4 days week−1 for 8 weeks. To assess the interaction of the higher intensity exercise with diet, a second endurance test (RUN2) was undertaken after 6 weeks at either 16 m min−1 or 28 m min−1. The NT group ran for a longer duration (increase of 77%) after FAT than CHO (239 ± 28 vs. 135 ± 30 min, P < 0.05) at 16 m min−1. There were no differences in RUN2 for the LOW group when rats ran at 16 m min−1 (454 ± 86 vs. 427 ± 75 min for CHO and FAT groups, respectively), but rats in the VMAX group fed FAT ran longer than rats fed CHO at 28 m min−1 (100 ± 28 vs. 58 ± 11 min, respectively, P < 0.05). FAT increased the activities of the enzymes citrate synthase, β‐hydroxyacyl‐CoA dehydrogenase and carnitine palmitoyl‐transferase compared to CHO (P < 0.01), but there was no systematic effect of training. We conclude: (1) there was no additive effect of a high‐fat diet on endurance performance when rats performed low‐intensity training; (2) running performance at 28 m min−1 was only enhanced by a high‐fat diet after more intense training; (3) diet‐induced and training‐induced adaptations that increase exercise capacity may be under independent control.
SAPID Solutions and Food Intake in Repeated Dehydration and Rehydration Periods in Rats
Authors: Scalera Giuseppe , Tarozzi Giorgio
Published: February 2003

In a previous report, it has been shown that water deprivation significantly affects the two‐bottle taste preferences and one‐bottle taste acceptance in rats when no food was available during tests. Since no food was available, the course of drinking was never interrupted by eating. Theoretically, if a rat faces a simultaneous choice between food and fluid, and if the course of drinking is interrupted by eating, these conditions might interfere with taste preferences, total fluid intake and eating in thirsty rats. The aims of the present experiments were: to ascertain whether food intake during both two‐bottle preference and one‐bottle acceptance tests in thirsty rats might be influenced by the palatability of the solutions; to verify whether the availability of food during tests influences taste preference and acceptance, and total fluid intake; to detect variations induced by dehydration on body weight and some plasma and urinary parameters that might interfere with food and fluid intake, taste preference and acceptance. Using naive rats, five groups of rats showing the same taste preferences for one of four prototypical tastes and water were selected. Then, both two‐bottle preference (Expt 1) and one‐bottle acceptance tests (Expt 2) were performed in rats deprived of water for either 12, 24, 36 or 48 h. The results showed that in both Expt 1 and Expt 2, inhibition of feeding and decrease of body weight during dehydration was very similar in all rats. The presence of food during the tests did not affect taste preference and acceptance. During Expt 1, after severe water deprivation (36 and 48 h), food intake was related to the palatability of the solution paired with water. When rats drank either NaCl or sucrose, they ate less food than rats drinking HCl, quinine, or water. In Expt 2, rats drinking NaCl solution as the only source of fluid ate significantly less food than all other groups. The intake of sucrose and/or NaCl solutions be may explained by two different post‐ingestion effects (energetic and osmotic). Since rats drinking either sucrose or NaCl ate less food but drank more fluid, they had a significantly higher fluid/food intake ratio than that of rats who drank water, quinine, or HCl, who ate more food but drank less fluid. The increase of the fluid/food intake ratio in rats drinking sucrose or NaCl was directly correlated with the length of dehydration. Self‐denial of food during dehydration may be responsible for overeating and overdrinking during the recovery period after tests. After dehydration lasting for 24 and 48 h, plasma [Na+], [protein], osmolality and haematocrit values increased but [K+] decreased. Urinary volume decreased but urinary [Na+] increased. These results are related to food and fluid intake, taste preference and acceptance after dehydration periods.
Effects of Prolonged Aerobic Exercise on Myocardial Responses to Ischaemia‐Reperfusion in the Rat
Authors: Venditti Paola , Masullo Piero , Di Meo Sergio , Agnisola Claudio
Published: February 2003

The effects of low‐intensity, prolonged swimming on functional recovery of the rat heart (Langendorff preparations) from ischaemia‐reperfusion (I/R) were investigated. Three groups of rats (120 days old) were used: sedentary rats (S) and rats exercised by a single bout of swimming lasting 5 (E5) or 8 h (E8), respectively. The effect of exercise on the response to I/R was related to an index of oxidative damage such as lipid peroxidation, as well as to the tissue antioxidant capacity and the response of heart tissue to in vitro oxidative stress. The intrinsic performance of E5 Langendorff preparations paced at 220 beats min−1 was also determined. A group of sedentary animals was used for H2O2‐treated preparations. The effect of antioxidant treatment on inotropic recovery during reperfusion was studied on preparations from 5 or 8 h swimming vitamin E‐treated (EVT5 and EVT8) and 5 or 8 h swimming untreated (EVU5 and EVU8) rats. Hearts from exercised animals displayed a reduced preischaemic inotropism, which in E5 rats was accompanied by an increase in the intrinsic heart rate. The lower intrinsic cardiac inotropism of E5 animals was confirmed in the paced preparations. The reduced contractility found in control hearts after addition of H2O2 to perfusion medium suggested that the low inotropism of E5 and E8 hearts was due to an exercise‐induced increase in reactive oxygen species. Inotropic recovery during reperfusion was low in the S hearts, was significantly increased in the E5 hearts, and was again reduced to the S level in the E8 hearts. In the E8 hearts the indexes of cellular damage (LDH release) and oxidative stress increased, and antioxidant capacity decreased, while in E5 hearts there was no evidence of significant changes in such parameters. Performance and reperfusion recovery of hearts from 5 h swimming rats was not affected by vitamin E treatment, while those of hearts from 8 h swimming rats was the highest observed. We suggest that the higher inotropic recovery during reperfusion in the hearts from the E5 rats is related to the negative inotropic effect of exercise. The fall in recovery following the 8 h exercise was instead related to the increased oxidative stress.
Regulation of Human Myometrial Contractility During Pregnancy and Labour: Are Calcium Homeostatic Pathways Important?
Authors: Tribe Rachel M.
Published: February 2003

If we are to develop new strategies for the treatment and management of preterm and dysfunctional term labour, it is imperative that we improve current understanding of the control of human uterine activity. Despite many studies of animal pregnancy, there is a paucity of knowledge relating to the complex control of human myometrium during pregnancy. It is hypothesized that human myometrium is relatively quiescent during the majority of pregnancy and that as term approaches there is cascade of molecular events that prepare the uterus for labour. This review will consider the cellular mechanisms involved in the regulation of human myometrial activity and the modulation of these by hormonal and mechanical signals. In particular, the contribution of calcium homeostatic pathways to the control of human myometrial contractility during gestation will be discussed.
Gustatory‐Salivary Reflexes Induce Non‐Adrenergic, Non‐Cholinergic Acinar Degranulation in the Rat Parotid Gland
Authors: Ekström J.
Published: February 2003

In the presence of the muscarinic blocker atropine, the α‐adrenoceptor blocker phentolamine and the β‐adrenoceptor blocker propranolol (2 mg kg−1 of each, I.P.), the numerical density of parotid acinar secretory granules was reduced by 32% in response to ascorbic acid (0.5 M) applied on the tongue every 30 s over 30 min in awake rats. This non‐adrenergic, non‐cholinergic (NANC) response was entirely dependent on an intact auriculo‐temporal nerve supply. The NANC mechanisms were found to be potentially responsible for almost all of the exocytotic response that occurs in the absence of the three autonomic receptor blockers. No sympathetic contribution to the exocytotic response was found and furthermore, studies in parasympathetically denervated glands showed that the sympathetic contribution to the salivary flow was small.
Reflex Cardiorespiratory Effects of Nociceptive Oesophageal Distension in the Decerebrate Rat
Authors: Pickering Mark , Campion Deirdre , Jones James F. X.
Published: February 2003

It is well established that painful distension of hollow viscera such as the oesophagus can evoke a reflex tachycardia and pressor response; however, the nature of the oesophageal afferent pathway(s) remains controversial. This study investigated the afferent arc which mediates these reflex cardiovascular changes in the decerebrate rat. In addition, the effect of oesophageal distension on the respiratory activity of the costal diaphragm was studied. Focal distension of the oesophagus (volume of 0.3 ml applied for 10 s) just above the diaphragmatic hiatus evoked a reproducible presssor response and tachycardia in the decerebrate rat. Respiration was transiently inhibited at the beginning of oesophageal distension and prior to the rise in blood pressure. Neuromuscular blockade with the nicotinic acetylcholine receptor blocker α‐bungarotoxin (140 μg bolus) had no effect on the magnitude of the cardiovascular response. Therefore the efferent supply to the striated muscle of the rat oesophagus was not essential in mediating this reflex. Signal averaging of the mean blood pressure response showed that neither selective ablation of oesophageal spinal afferents nor bilateral vagotomy altered the early trajectory of the pressure response. Bilateral vagotomy reduced the peak magnitude of the response to sustained oesophageal distension. In contrast, selective removal of spinal afferents had no effect on the response. Ablation of both neural pathways was essential to abolish the reflex cardiovascular and respiratory responses. It can be concluded that both vagal and spinal afferent pathways are utilised in the reflex cardiorespiratory response to painful oesophageal distension. Although ablation of one neural pathway had no effect on the response it was still implicated in the reflex, since ablation of both pathways was necessary to prevent the cardiorespiratory changes. This study emphasises the need for caution when inferences are made concerning single selective ablations of multiply innervated organs.
Right Atrial Stretch Induces Renal Nerve Inhibition and c‐fos Expression in Parvocellular Neurones of the Paraventricular Nucleus in Rats
Authors: Pyner S. , Deering J. , Coote J. H.
Published: February 2003

The paraventricular nucleus of the hypothalamus plays a pivotol role in the regulation of plasma volume. Part of the response to an increase in volume load is an inhibition of renal sympathetic nerve activity. The present experiments were designed to determine which subnuclei of the paraventricular nucleus are involved in this sympatho‐inhibitory response. Experiments were performed on anaesthetised rats. Activated neurones were recognised by the expression of the early gene c‐fos, identified by immunohistochemical labelling of its protein product Fos. Plasma volume loading with 4% Ficoll 70, using an infusion‐withdrawal procedure (2 ml over 1 min) repeated 15 times over 1 h revealed a total of 775 ± 101 (n = 6) Fos‐positive neurones scattered throughout both the magnocellular and parvocellular subnuclei. In comparison, sustained hypertension resulted in 452 ± 56 (n = 3) Fos‐positive neurones similarly distributed, whereas a normotensive control group (n = 3) displayed 115 ± 18 Fos‐positive neurones. Because of this lack of a specific effect we used a more selective stimulation of right atrial receptors via a balloon placed at the junction of the superior vena cava and the right atrium so it did not impede venous return. Inflation of the balloon inhibited renal sympathetic nerve activity (36 ± 5%, n = 7) and repetitive inflation over 1 h resulted in c‐fos activation of a small number of neurones (54 ± 14) located only in the parvocellular subnuclei. Whether these are inhibitory interneurones acting within the paraventricular nucleus, or spinally projecting neurones which inhibit or excite renal sympathetic activity by an action in the spinal cord remains to be determined.
Protein Kinase C Regulation of Rat Jejunal Transport Systems: Mechanisms Involved in Bicarbonate Absorption
Authors: Orsenigo Maria Novella , Tosco Marisa , Baroni Maurizio Davide , Bazzini Claudia , Laforenza Umberto , Faelli Alide
Published: February 2003

We examined whether protein kinase C (PKC) modulates the transport systems involved in bicarbonate movements across the plasma membranes of rat jejunum. Results of enzymatic assays provide evidence that under basal conditions conventional PKC (cPKC) is present in both basolateral membranes (BLMs) and apical (brush border) membranes (BBMs) of the enterocyte. In BLMs the basal expression of the kinase is low compared to expression in BBMs; however, treatment with Ca2+ and phorbol 12‐myristate 13‐acetate (PMA) causes a significant increase, thus suggesting an asymmetrical kinase translocation. To explore the effect of PKC activation on membrane‐bound transport mechanisms, ‘in vitro’ phosphorylated membrane vesicles were used to perform uptake studies. Results suggest that PKC activation exerts an inhibitory effect on the basolateral Cl−‐HCO3− antiporter, whereas the basolateral HCO3− conductive pathway seems to be stimulated and Cl− conductance unaffected. The apical, but not basolateral, Na+‐H+ exchanger is inhibited by PKC activation. The specificity of the response to PKC was confirmed by using the kinase inhibitor staurosporine or the inactive phorbol ester 4‐α‐PMA. The inhibition of both apical Na+‐H+ and basolateral Cl−‐HCO3− exchange activities suggests that the overall action of PKC causes a reduction of transepithelial bicarbonate transport.
Noxious Somatic Inputs to Hypothalamic‐Midbrain Projection Neurones: a Comparison of the Columnar Organisation of Somatic and Visceral Inputs to the Periaqueductal Grey in the Rat
Authors: Parry D. M. , Semenenko F. M. , Conley R. K. , Lumb B. M.
Published: February 2003

The induction of Fos protein was used to localise hypothalamic neurones activated by noxious somatic stimulation. This was combined with retrograde transport of fluorescent latex microspheres from identified ‘pressor’ and ‘depressor’ sites in the dorsolateral/lateral or ventrolateral columns of the periaqueductal grey (PAG). Fos‐positive neurones were found throughout the rostral hypothalamus. Of those neurones activated by noxious somatic stimuli that projected to the PAG all but one was retrogradely labelled from sites that included the lateral column. Only one neurone was double labelled following injection of tracer at a depressor site in the ventrolateral PAG. This is in marked contrast to visceroresponsive hypothalamic neurones, a larger proportion of which project to the PAG and which, as reported previously, preferentially target depressor sites in the ventrolateral sector. These results are discussed in relation to the roles of the anterior hypothalamus and the different functional columns of the PAG in co‐ordinating autonomic and sensory functions in response to nociceptive inputs originating in different peripheral domains.
A Simple Method for Generating a Blood Pressure‐Unit Activity Relationship for Central Cardiovascular Neurons in the Rat
Authors: Cividjian A. , Rentero N. , McAllen R. , Quintin L.
Published: February 2003

One way to identify central cardiovascular neurons is to consider their barosensitivity, for example by plotting changes in their single unit activity as a function of evoked changes in blood pressure. To simplify the genesis of such pressure‐activity relationships, a coronary angioplasty catheter was threaded into the aorta of anaesthetized rats and the balloon inflated to raise the blood pressure mechanically. Here, such a procedure is exemplified for cardiac vagal motoneurons in the medulla oblongata in eight rats. This simplification bypasses potentially problematic surgery and minimizes deterioration of the animal.
Neuroendocrine Function and Chronic Inflammatory Stress
Authors: Harbuz Michael
Published: February 2003

The factors regulating susceptibility and severity of autoimmune diseases are poorly understood. That neuroendocrine factors are critical modulators in this regard is self‐evident. For example, there are major gender differences in susceptibility with women at greater risk than men of, for example, rheumatoid arthritis (RA) and multiple sclerosis (MS). The hypothalamo‐pituitary‐adrenal (HPA) axis has rightly attracted a considerable amount of attention. Of particular interest has been the hypothesis that susceptibility to autoimmune disease may be related to an impaired responsiveness of the HPA axis; that is, an inability to mount an appropriate cortisol response with which to down‐regulate the immune system might allow the immune system to rampage unchecked and attack self. This hypothesis links regulation of the release from the adrenal gland of the potent anti‐inflammatory glucocorticoids to the disease process. Endogenous glucocorticoids are crucial for the regulation of the severity of the disease process. The hypothesis proposing a link between a hyporesponsive HPA axis and susceptibility to disease is compelling. However, evidence from a number of sources has suggested that this may not be the entire story and alterations in the activity of the HPA axis have not been consistently observed in patients with RA. This review will concentrate on recent findings concerning the HPA axis in determining susceptibility to, and in regulating the severity of, inflammatory processes in autoimmune disease. These studies have revealed that a single exposure to endotoxin can confer protection to subsequent development of inflammation in an arthritis model in both neonatal and adult rats. Behavioural differences within a single population of rats are associated with differences in the plasma corticosterone responses to stress. However, relative hyporesponsiveness is not reflected by an increase in the severity of inflammation. In humans with RA the dexamethasone‐corticotrophin‐releasing factor (CRF) test has revealed two distinct sub‐populations of patients. Studies in patients with MS have shown that this is not related to depression but rather to the severity of the disease. A better understanding of these complex neuroendocrine interactions may lead to novel clinical interventions.
An Arterially Perfused Decerebrate Preparation of Suncus Murinus (House Musk Shrew) for the Study of Emesis and Swallowing
Authors: Smith Julia E. , Paton Julian F. R. , Andrews Paul L. R.
Published: February 2003

Arterially perfused, decerebrate preparations of the insectivore, Suncus murinus were made to determine whether the emetic reflex could be activated in such a preparation using a range of stimuli shown to be emetic in conscious or anaesthetised Suncus. Efferent phrenic and vagus nerve activities and electromyograms (EMGs) from the temporalis, abdominal oesophagus and trapezius muscles were recorded, as well as longitudinal shortening of the oesophagus and dorso‐ventral movements of the thorax. The preparations swallowed spontaneously every 0.6 to 6.5 min. The duration of a swallow was 3.1 ± 0.3 s (recorded as the time taken for the oesophagus to shorten and recover to its resting position) and the oesophagus shortened by 3.5 ± 0.4 mm during a swallow. The emetic reflex was activated by electrical stimulation (30 Hz, 10‐20 V, 0.2 ms pulse width, for 30 s) of abdominal vagal afferents (latency < 30 s) or by arterial perfusion with either 40 nM of the capsaicin analogue resiniferatoxin (latency 1.7 ± 0.6 min), 6 μM nicotine (latency 1.6 ± 0.1 min) or 1 μM of the phosphodiesterase IV inhibitor CP‐80,633 (latency 8.9 ± 3.9 min). These emetic stimuli produced somatic and visceral movements in Suncus preparations indicative of activation of the emetic reflex. There were pronounced contractions of the thorax that occurred simultaneously with oesophageal shortening and mouth opening, separated by thorax expansion and a burst of phrenic nerve activity. During emetic‐like episodes, oesophageal shortenings were only 0.84 ± 0.1 s in duration, faster than the duration of shortening observed during swallowing (cf. swallowing, 3.1 ± 0.3 s; P < 0.0001). The shortening of the oesophagus during emetic‐like episodes was 6.2 ± 0.4 mm, which was greater than the shortening seen during swallowing (cf. swallowing, 3.5 ± 0.4 mm; P < 0.0001). We conclude that the emetic reflex can be activated in our Suncus preparations and that this non‐sentient small adult animal model can now be used to study the neurophysiology and pharmacology of swallowing and emesis.
Putative involvement of crustacean hyperglycemic hormone isoforms in the neuroendocrine mediation of osmoregulation in the crayfishAstacus leptodactylus
Authors: Serrano Laetitia , Blanvillain Gaëlle , Soyez Daniel , Charmantier Guy , Grousset Evelyse , Aujoulat Fabien , Spanings-Pierrot Céline
Published: February 2003

This study investigates the involvement of eyestalk neuroendocrine factors on osmoregulation in the crayfish Astacus leptodactylus maintained in freshwater. Eyestalk removal was followed by a significant decrease in hemolymph osmolality and Na+ concentration and by a 50% increase in mass after one molting cycle. Several neurohormones have been isolated from the sinus gland through high-performance liquid chromatography (HPLC), and different crustacean hyperglycemic hormone (CHH)-related peptides, including stereoisomers (L-CHH and D-Phe3 CHH), have been identified by direct enzyme-linked immunosorbent assay (ELISA). A glucose quantification bioassay demonstrated a strong hyperglycemic activity following injection of the immunoreactive chromatographic fractions and showed that the D-Phe3 CHH was the most efficient. Destalked crayfish were then injected with purified CHH HPLC fractions. The D-Phe3 CHH fraction significantly increased the hemolymph osmolality and Na+ content 24 h after injection. Two other CHH-related peptides caused a smaller increase in Na+ concentration. No significant variation was observed in hemolymph Cl- concentration following injection of any of the CHH isoforms. These results constitute the first observation of the effects of a CHH isoform, specifically the D-Phe3 CHH, on osmoregulatory parameters in a freshwater crustacean. The effects of eyestalk ablation and CHH injection on osmoregulation and the identification of different CHH-related peptides and isoforms in crustaceans are discussed.
Myogenic cell cycle duration inHarpagiferspecies with sub-Antarctic and Antarctic distributions: evidence for cold compensation
Authors: Brodeur Julie C. , Calvo Jorge , Clarke Andrew , Johnston Ian A.
Published: February 2003

In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth and nuclear turnover. We measured the cell cycle and S-phase duration of myogenic cells in the fast myotomal muscle of two closely related Harpagifer species by cumulative S-phase labelling with 5-bromo-2′-deoxyuridine (BrdU). Harpagifer antarcticus is a stenothermal species from the Antarctic peninsula (experiencing temperatures of -2°C to +1°C) and Harpagifer bispinis is a eurythermal species from the Beagle Channel, Tierra del Fuego (living at +4°C in winter and up to 11°C in summer). Specific growth rates in the adult stages studied were not significantly different from zero. Myogenic progenitor cells were identified using an antibody against c-met. Seventy-five percent of the c-met+ve cells were in a proliferative state in both species. Cell cycle time was 150 h at 5°C and 81.3 h at 10°C in H. bispinis (Q10=3.4). Cell cycle duration was 35% shorter in H. antarcticus at 0°C (111 h) than in H. bispinis at 5°C. The predicted cell cycle time for H. bispinis at 0°C(based on the Q10 relationship) was 277 h, which was more than double that measured for the Antarctic species at this temperature. The results obtained are compatible with an evolutionary adjustment of cell cycle time for function at low temperature in the Antarctic species.
Threatening Nonprofit Hospital Tax Exemption
Authors: Horwitz Jill R.
Published: January 2024

This Viewpoint discusses regulation of nonprofit hospitals in a way that will advance their charitable purposes without eliminating their tax exemption status.
Sex Disparities in Ophthalmology From Training Through Practice
Authors: Rousta Nikki , Hussein Isra M. , Kohly Radha P.
Published: January 2024

Importance

Sex-based research in medicine has revealed inequities against females on almost every metric at almost every career stage; ophthalmology is no exception.

Objective

To systematically review the experiences of females in ophthalmology (FiO) from training through practice in high-income countries (HICs).

Evidence Review

A systematic review of English-language studies, published between January 1990 and May 2022, relating to FiO in HICs was performed. PubMed, MEDLINE, and Embase electronic databases were searched, as well as the Journal of Academic Ophthalmology as it was not indexed in the searched databases. Studies were organized by theme at each career stage, starting in medical school when an interest in ophthalmology is expressed, and extending up to retirement.

Findings

A total of 91 studies, 87 cross-sectional and 4 cohort, were included. In medical school, mentorship and recruitment of female students into ophthalmology was influenced by sex bias, with fewer females identifying with ophthalmologist mentors and gender stereotypes perpetuated in reference letters written by both male and female referees. In residency, females had unequal learning opportunities, with lower surgical case volumes than male trainees and fewer females pursued fellowships in lucrative subspecialties. In practice, female ophthalmologists had lower incomes, less academic success, and poorer representation in leadership roles. Female ophthalmologists had a greater scholarly impact factor than their male counterparts, but this was only after approximately 30 years of publication experience. Pervasive throughout all stages of training and practice was the experience of greater sexual harassment among females from both patients and colleagues. Despite these disparities, some studies found that females reported equal overall career satisfaction rating with males in ophthalmology, whereas others suggested higher burnout rates.

Conclusions and Relevance

Ophthalmology is approaching sex parity, however, the increase in the proportion of females in ophthalmology had not translated to an increase in female representation in leadership positions. Sex disparities persisted across many domains including recruitment, training, practice patterns, academic productivity, and income. Interventions may improve sex equity in the field.
Inflammatory Rhabdomyoblastic Tumor of the Posterior Pharyngeal Wall
Authors: Baker Emily R. , Allen Meredith A. , Jones Ryan M. , Gillespie M. Boyd , Wood C. Burton
Published: January 2024

This case report describes a healthy man in his 40s who presented with a 1-year history of snoring, sleep apnea, dysphonia, and dysphagia owing to a large mass of the posterior pharynx and was diagnosed with an inflammatory rhabdomyoblastic tumor.
A Flexible and Electrically Conductive Liquid Metal Adhesive for Hybrid Electronic Integration
Authors: Pozarycki Tyler A. , Zu Wuzhou , Wilcox Brittan T. , Bartlett Michael D.
Published: January 2024

Electrical and mechanical integration approaches are essential for emerging hybrid electronics that must robustly bond rigid electrical components with flexible circuits and substrates. However, flexible polymeric substrates and circuits cannot withstand the high temperatures used in traditional electronic processing. This constraint requires new strategies to create flexible materials that simultaneously achieve high electrical conductivity, strong adhesion, and processibility at low temperature. Here, an electrically conductive adhesive is introduced that is flexible, electrically conductive (up to 3.25×105S m−1) without sintering or high temperature post‐processing, and strongly adhesive to various materials common to flexible and stretchable circuits (fracture energy 350 <Gc< 700 J m−2). This is achieved through a multiphase soft composite consisting of an elastomeric and adhesive epoxy network with dispersed liquid metal droplets that are bridged by silver flakes, which form a flexible and conductive percolated network. These inks can be processed through masked deposition and direct ink writing at room temperature. This enables soft conductive wiring and robust integration of rigid components onto flexible substrates to create hybrid electronics for emerging applications in soft electronics, soft robotics, and multifunctional systems.
Constructing Asymmetrical Coordination Microenvironment with Phosphorus‐Incorporated Nitrogen‐Doped Carbon to Boost Bifunctional Oxygen Electrocatalytic Activity
Authors: Li Zhijun , Ji Siqi , Liu Hongxue , Xu Chang , Guo Chunmin , Lu Xue , Sun Haixin , Dou Shuo , Xin Shixuan , Horton J. Hugh , He Cheng
Published: January 2024

Carbon‐based metal‐free electrocatalysts have been recognized as inexpensive alternatives to afford excellent activity in oxygen reduction/evolution reactions (ORR/OER). Nevertheless, precisely identifying the local active sites and tailoring the corresponding electronic properties to enhance the reaction kinetics remain challenging. Herein, a facile strategy to create a metal‐free electrocatalyst comprised of a mesoporous nitrogen‐doped carbon matrix with phosphorus incorporation (NPC) is described. The as‐prepared NPC‐950 electrocatalyst demonstrates superior ORR activity under alkaline and acidic conditions with half‐wave potentials of 0.88 and 0.72 V, respectively, comparable to commercial Pt/C (0.85 and 0.76 V) and overwhelmingly superior to other N‐doped carbon catalyst materials. In addition, a remarkable promotion of OER activity under alkaline conditions is observed. Notably, a zinc–air battery equipped with this NCP‐950 electrocatalyst exhibits exceptional performance in peak power density, specific capacity, and long‐term operation durability. Theoretical calculations uncover that the incorporation of phosphorus in NC material results in effective charge density redistribution, thus modulating the electronic properties of active sites to achieve optimum adsorption and desorption of ORR intermediates. The work provides a deep understanding of active sites in heteroatom‐doped carbon materials and highlights the importance of the electronic properties modulation in oxygen bifunctional electrocatalytic activity.
Interfacial Engineering Using Covalent Organic Frameworks in Polymer Composites for High‐Temperature Electrostatic Energy Storage
Authors: Xie Zongliang , Le Khoi , Li He , Pang Xi , Xu Tianlei , Altoé Virginia , Klivansky Liana M. , Wang Yunfei , Huang Zhiyuan , Shelton Steve W. , Gu Xiaodan , Liu Peng , Peng Zongren , Liu Yi
Published: January 2024

The use of inorganic nanofillers has been an effective method to improve high‐temperature capacitive performance of dielectric polymers, though there are unmet challenges such as undesirable organic–inorganic compatibility, and low efficiencies and energy densities. Herein, a surface functionalization strategy using covalent organic frameworks (COFs) is employed to address such challenges in realizing high‐performing polymer composites. Specifically, core–shell structured nanoparticles, where ZrO2 nanoparticles act as the core and a COF material forms the shell, are constructed and composited with the polyetherimide (PEI) matrix. The design leverages the high electron affinity (EA) of the outer COF shell to create energy traps, thereby capturing free charges and limiting electrical conduction. Concurrently, the low EA and wide bandgap of the ZrO2 core introduce energy barriers to impede charge injection and migration. This orchestrated “energy level cascade” results in a marked reduction of leakage current and energy loss. The resulting polymer composite showcases an impressive discharged energy density of 6.21 J cm−3 at an efficiency above 90%, with a maximum discharged energy density reaching 7.43 J cm−3 at 150 °C. These performance metrics position the PEI/ZrO2@COF polymer composite to surpass or be on par with state‐of‐the‐art high‐temperature PEI composites and other advanced polymer dielectrics.
Boosting Nitrate to Ammonia via the Optimization of Key Intermediate Processes by Low‐Coordinated Cu–Cu Sites
Authors: Huang Kun , Tang Kun , Wang Mohan , Wang Yujiao , Jiang Tongtong , Wu Mingzai
Published: January 2024

The electrochemical reduction of nitrate to ammonia (NO3RR) has emerged as a promising but challenging orientation in sustainable development. Cu is one of the most effective NO3RR catalysts. However, the accumulation of NO2− on their surface has erected bars to the further improvement of NO3RR efficiency. Herein, Cu‐based electrocatalyst with low‐coordinated Cu atoms (Cu‐LC) is synthesized via the instantaneous ablation and rapid cooling of the Cu target by pulse laser and proposed as a new NO3RR electrocatalyst, which exhibits enhanced NO3RR activity with NH3 selectivity of 97.01%, yield rate of 0.624 mmol h−1 cm−2 at −0.8 V versus RHE and long‐term durability, superior to most reported Cu‐based catalysts. The introduction of low‐coordinated Cu sites upshifts the Cu d‐band center to near the Fermi Level, enhancing the adsorption of key intermediates (*NO2, *NO) in NO3RR, and also effectively regulating the generation of *NO2 and hydrogenation process, inhibiting the accumulation of NO2− on the Cu‐LC surface, thus achieving efficient NH3 production. Furthermore, when evaluated as cathode material in Zn–NO3− battery, an open circuit voltage of 1.3 V and a power density of 3.1 mW cm−2 are achieved by the Cu‐LC‐based battery, highlighting a promising multifunctional system for ammonia production and energy supply.
Enhanced Mechanical Properties, Corrosion Resistance, Cytocompatibility, Osteogenesis, and Antibacterial Performance of Biodegradable Mg–2Zn–0.5Ca–0.5Sr/Zr Alloys for Bone‐Implant Application
Authors: Tong Xian , Dong Yilong , Zhou Runqi , Shen Xinkun , Li Yuncang , Jiang Yue , Wang Huiyuan , Wang Jinguo , Lin Jixing , Wen Cuie
Published: January 2024

Magnesium (Mg) alloys are widely used in bone fixation and bone repair as biodegradable bone‐implant materials. However, their clinical application is limited due to their fast corrosion rate and poor mechanical stability. Here, the development of Mg–2Zn–0.5Ca–0.5Sr (MZCS) and Mg–2Zn–0.5Ca–0.5Zr (MZCZ) alloys with improved mechanical properties, corrosion resistance, cytocompatibility, osteogenesis performance, and antibacterial capability is reported. The hot‐extruded (HE) MZCZ sample exhibits the highest ultimate tensile strength of 255.8 ± 2.4 MPa and the highest yield strength of 208.4 ± 2.8 MPa and an elongation of 15.7 ± 0.5%. The HE MZCS sample shows the highest corrosion resistance, with the lowest corrosion current density of 0.2 ± 0.1 µA cm−2 and the lowest corrosion rate of 4 ± 2 µm per year obtained from electrochemical testing, and a degradation rate of 368 µm per year and hydrogen evolution rate of 0.83 ± 0.03 mL cm−2 per day obtained from immersion testing. The MZCZ sample shows the highest cell viability in relation to MC3T3‐E1 cells among all alloy extracts, indicating good cytocompatibility except at 25% concentration. Furthermore, the MZCZ alloy shows good antibacterial capability against Staphylococcus aureus.