Effect of platelet-activating factor on food intake, cloacal temperature, voluntary activity and crop emptying rate in chicks.

Platelet-activating factor (PAF) plays a significant role in several leucocyte functions, including platelet aggregation and inflammation. Additionally, PAF has a role in the behavioral and physiological changes in mammals. However, the effect of PAF has not been well studied in birds. Therefore, the study aimed to determine if PAF affects feeding behavior, voluntary activity, cloacal temperature, and feed passage through the digestive tract in chicks (Gallus gallus). We also studied the involvement of PAF in the innate immune system induced by lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria. Both intraperitoneal (IP) and intracerebroventricular (ICV) injections of PAF significantly decreased food intake. IP injection of PAF significantly decreased voluntary activity and slowed the feed passage from the crop, whereas ICV injection had no effect. Conversely, ICV injection of PAF significantly increased the cloacal temperature, but IP injection had no effect. The IP injection of LPS significantly reduced the mRNA expression of lysophosphatidylcholine acyltransferase 2, an enzyme responsible for PAF production in the heart and pancreas. On the other hand, LPS significantly increased the mRNA expression of the PAF receptor in the peripheral organs. The present study shows that PAF influences behavioral and physiological responses and is related to the response against bacterial infections in chicks.

Biomechanical analysis of load distribution in porcine hip joints at different acetabular coverages.

BACKGROUND: Developmental dysplasia of the hip causes secondary osteoarthritis. Finite element analysis suggests high hip joint contact pressure in patients with hip dysplasia and a reduction in contact pressure after periacetabular osteotomy. However, few biomechanical studies have examined the load distribution in the hip joint. This study aimed to investigate the biomechanical properties of load distribution in porcine hip joints at different acetabular coverages. METHODS: Six porcine hip joints were analyzed using three models: 1) neutral coverage, 2) 15° under-coverage (defined as dysplasia model), and 3) 15° over-coverage created by varying the acetabular coverage. The load distribution was assessed using a pressure-mapping sensor system after applying a loading force of 100 N to the hip joint. RESULTS: In the dysplasia model, the load was concentrated at the acetabular rim; in the neutral and over-coverage models, it was dispersed. The average contact pressure was significantly higher in the dysplasia model than in the neutral coverage model ([0.42 vs. 0.3 MPa]; p = 0.004). The contact area was significantly smaller in the dysplasia model than in the neutral coverage model ([250.7 vs. 345.0 mm2]; p = 0.004). No significant differences were observed in contact pressure or area between the neutral and over-coverage models. CONCLUSIONS: Insufficient acetabular coverage in the dysplasia model demonstrated higher contact pressure and smaller contact area than the neutral model. Conversely, the contact pressure and area in the over-coverage model did not differ significantly from those in the normal model. Therefore, surgeons should note that acetabular coverage overcorrection has limited effect; normalization is crucial during periacetabular osteotomy.

Possible role of neuropeptide Y on zymosan- and lipopolysaccharide-induced change in gastrointestinal feed passage via the medulla oblongata in chicks.

Zymosan is a fungi-derived pathogen-associated molecular pattern. It activates the immune system and induces the reduction of feed passage rate in the gastrointestinal tract of vertebrates including birds. However, the mechanism mediating the zymosan-induced inhibition of feed passage in the gastrointestinal tract remains unknown. Since the medulla oblongata regulates the digestive function, it is plausible that the medulla oblongata is involved in the zymosan-induced inhibition of feed passage. The present study was performed to identify the genes that were affected by zymosan within the medulla oblongata of chicks (Gallus gallus) using an RNA sequencing approach. We found that mRNAs of several bioactive molecules including neuropeptide Y (NPY) were increased with an intraperitoneal (IP) injection of zymosan. The increase of mRNA expression of NPY in the medulla oblongata was also observed after the IP injection of lipopolysaccharide, derived from gram-negative bacteria. These results suggest that medullary NPY is associated with physiological changes during fungal and bacterial infection. Furthermore, we found that intracerebroventricular injection of NPY and its receptor agonists reduced the feed passage from the crop. Additionally, the injection of NPY reduced the feed passage from the proventriculus to lower digestive tract. NPY also suppressed the activity of duodenal activities of amylase and trypsin. The present study suggests that fungi- and bacteria-induced activation of the immune system may activate the NPY neurons in the medulla oblongata and thereby reduce the digestive function in chicks.

Effect of ornithokinin on feeding behavior, cloacal temperature, voluntary activity and crop emptying rate in chicks.

Bradykinin is a well-studied bioactive peptide associated with several physiological functions, including vasodilation and inflammation, in mammals. However, its avian homolog, ornithokinin, has received less research attention in birds. Therefore this study aimed to investigate the effect of intraperitoneal (IP) and intracerebroventricular (ICV) injections of ornithokinin on feeding behavior, cloacal temperature, voluntary activity, crop emptying rate, and blood constituents in chicks (Gallus gallus). We also investigated the effect of lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria, on ornithokinin-associated gene expression was also investigated to determine whether activation of the ornithokinin system is induced by bacterial infection. Both IP and ICV injections of ornithokinin significantly decreased feed intake, cloacal temperature, voluntary activity, and crop emptying rate in chicks, but they did not affect the plasma concentration of corticosterone. Additionally, LPS significantly increased the expression of ornithokinin B2 receptor mRNA in several organs. Hence, ornithokinin is associated with a range of physiological responses in chicks and may be related to their response to bacterial infection.

Poly I:C and R848 facilitate nitric oxide production via inducible nitric oxide synthase in chicks.

Nitric oxide (NO) is a gaseous bioactive molecule associated with many physiological functions including vasodilation and neurotransmission. NO also plays an important role in immune responses during viral infections in mammals. However, there is a paucity of knowledge regarding the involvement of NO in viral infections in birds. Therefore, the purpose of the present study was to determine if intraperitoneal (IP) injection of poly I:C and R848 (resiquimod), which are analogues of virus component, affects NO production in chicks (Gallus gallus) as a bird model. The involvement of inducible NO synthase (iNOS) in poly I:C- and R848-induced anorexia and corticosterone release was also investigated. These virus analogues significantly increased plasma NO metabolites (NOx) concentrations. IP injection of poly I:C and R848 significantly increased iNOS mRNA expression in several organs including the liver. On the other hand, poly I:C and R848 significantly decreased mRNA expressions of endothelial NOS and neural NOS in several organs, indicating that induction of iNOS might be responsible for increased NOx levels in plasma. This finding was further confirmed by using a selective iNOS inhibitor, S-methylisothiourea sulfate (SMT), which abolished the poly I:C- and R848-induced increase in plasma NOx concentration. In addition, SMT partly attenuated the poly I:C- and R848-induced increase in plasma corticosterone concentration, suggesting that corticosterone release induced by these virus analogues may be partly mediated by iNOS. Collectively, the present results suggest that viral infections facilitate NO production by inducing iNOS. The liver would play an important role in the NO production because the response in iNOS mRNA expression to poly I:C and R848 was remarkable. The present results also suggest that NO is associated with corticosterone release in birds under viral infection.

Effect of lithium chloride on food intake, cloacal temperature, voluntary activity, and crop-emptying rate in chicks.

Infections frequently accompany with non-specific symptoms such as anorexia and hyperthermia. In addition, there may be unpleasant sensations such as visceral discomfort during infection. Lipopolysaccharide (LPS), a Gram-negative bacteria cell wall component, is known to induce the unpleasant sensation of conditioned taste aversion in mammals. However, the relationship between unpleasant sensations and changes in behavior and physiological conditions has not been investigated extensively in birds. Lithium chloride (LiCl) is a compound that induces unpleasant sensations, including visceral discomfort, although its effects on behavior and physiological conditions have also not been investigated extensively in birds. Thus, the present study was aimed to investigate the effect of an intraperitoneal (IP) injection of LiCl on conditioned visual aversion, food intake, cloacal temperature, voluntary activity, crop-emptying rate, and blood constituents in chicks (Gallus gallus). We also examined the effect of IP injections of LPS and zymosan, a cell wall component of fungus, on conditioned visual aversion formation. First, IP injection of LiCl was confirmed to induce conditioned visual aversion in chicks. An IP injection of LiCl significantly decreased food intake, voluntary activity, and crop-emptying rate but did not affect the temperature. In addition, the injection of LiCl significantly increased plasma corticosterone concentration, indicating that LiCl serves as a stressor in chicks. Finally, IP injections of LPS and zymosan were found to induce conditioned visual aversion in chicks. Collectively, these results suggest that LiCl induces conditioned aversion, anorexia, hypoactivity, and inhibition of crop-emptying in chicks. In addition, LPS and zymosan would induce unpleasant sensations in chicks.

Patient body mass index modifies the association between waiting time for hip fracture surgery and in-hospital mortality: A multicenter retrospective cohort study.

BACKGROUND: Patient body mass index (BMI) plays an important role in stress exposure, especially in elderly patients with hip fracture. However, how BMI modifies the relationship between the waiting time for surgery and mortality remains unclear. METHODS: We investigated the association between waiting time and mortality using a nationwide multicenter database of patients undergoing hip fracture surgery. The primary outcome was in-hospital mortality and secondary outcomes were complications. We performed prespecified subgroup analysis with stratification by BMI. RESULTS: Overall, 305,846 patients (mean age, 83.5; standard deviation [SD], 8.2); women, 79.5% (n = 243,214) were included in our study. A cubic spline curve revealed two inflection points in the association between waiting time and mortality, and we statistically divided patients into three groups accordingly: the reference group (80,110 patients [26.2%] who waited 1 day for surgery), the delayed group (184,778 patients [60.4%] who waited 2-6 days for surgery), and the extremely delayed group (40,958 patients [13.4%] who waited more than 6 days for surgery). Multivariable logistic regression models showed that the odds of mortality in the delayed group was 14% higher than that in the reference group (adjusted odds ratio [aOR], 1.14; p = 0.002), whereas the odds of mortality in the extremely delayed group was 52% higher than that of the reference group (aOR, 1.52; p < 0.001). Patients with lower BMI were more negatively affected by delayed surgery compared to patients with normal BMI (p for interaction = 0.002). Respiratory disorders were most frequent and the spline curve was accordant with in-hospital mortality. CONCLUSION: Patients underwent surgery within 1 day, particularly with lower BMI, had a lower mortality than normal BMI. To optimize limited health care resource, patient's BMI should be considered for hip fracture management, and further investigation in prospective study should be needed to address causal relationship. LEVEL OF EVIDENCE: Therapeutic Level III.

Periprosthetic fragility fracture of the femur after primary cementless total hip arthroplasty.

OBJECTIVES: Periprosthetic bone fragility due to stress shielding (SS) can be a risk factor of periprosthetic fracture after cementless total hip arthroplasty (THA). We aimed to obtain epidemiological information on periprosthetic fragility fracture of the femur (PPFF) after THA. METHODS: We retrospectively reviewed the medical records of 1062 hips that had undergone cementless THA. We evaluated the epidemiological data as well as the features of PPFFs. RESULTS: Of the 1062 hips, 8 (0.8%) were diagnosed with PPFFs. The survival rates, with the occurrence of PPFF as the end point, were 99.2% and 97.6% at 10 and 16 years postoperatively, respectively. When patients were classified as having either mild or severe SS on radiographs 5 years postoperatively, there was no significant difference in the survival rate, with PPFF as the end point. CONCLUSIONS: In our cases, the incidence of PPFF after cementless THA was 0.8%.

Prostaglandin E2-induced anorexia involves hypothalamic brain-derived neurotrophic factor and ghrelin in chicks.

Central administration of prostaglandin E2 (PGE2) is associated with potent anorexia in rodents and chicks, although hypothalamic mechanisms are not fully understood. The objective of the present study was to identify hypothalamic nuclei and appetite-related factors that are involved in this anorexigenic effect, using chickens as a model. Intracerebroventricular injection of 2.5, 5, and 10 nmol of PGE2 suppressed food and water intake in broiler chicks in a dose-dependent manner. c-Fos immunoreactivity was increased in the paraventricular nucleus (PVN) at 60 min post injection of 5 nmol of PGE2. Under the same treatment condition, hypothalamic expression of melanocortin receptor 3 and ghrelin mRNAs increased, whereas neuropeptide Y receptor sub-type 5 and tropomyosin receptor kinase B (TrkB) mRNAs decreased in PGE2-treated chicks. In the PVN, chicks injected with PGE2 had more brain-derived neurotrophic factor (BDNF), ghrelin, and c-Fos mRNA but less corticotrophin-releasing factor receptor 1 (CRFR1), CRFR2, and TrkB mRNA expression. In conclusion, PGE2 injection resulted in decreased food and water intake that likely involves BDNF and ghrelin originating in the PVN. Because the anorexigenic effect is so potent and hypothalamic mechanisms are similar in chickens and rodents, a greater understanding of the role of PGE2 in acute appetite regulation may have implications for treating eating and metabolic disorders in humans.

Role of nitric oxide on zymosan-induced inhibition of crop emptying in chicks.

Zymosan, a component of yeast cell walls, reduces feed passage through the digestive tract in chicks (Gallus gallus), although the mechanism mediating this effect is poorly understood. Nitric oxide (NO) is associated with a variety of biological actions including effects on the immune system. In addition, it has been suggested that NO is involved in relaxation of the digestive tract and affects feed passage in mammals. It is therefore possible that NO might be related to zymosan-induced reduction of feed passage in chicks. However, the role of NO on the effect of zymosan feed passage has not been clarified yet. Thus, the purpose of the present study was to investigate whether NO is associated with zymosan-induced alteration of feed passage in chicks. Intraperitoneal (IP) injection of zymosan significantly increased plasma nitrate and nitrite (NOx) concentrations at 6 h after injection. Zymosan-induced elevation of plasma NOx concentration was abolished by co-injection of S-methylisothiourea (SMT), a selective inhibitor for inducible NO synthase (iNOS), indicating that zymosan facilitated the induction of iNOS. Furthermore, because zymosan increased iNOS mRNA expression in the digestive tract, NO is likely associated with the effect of zymosan on the digestive tract. IP injection of NO donors significantly decreased crop emptying rate, suggesting that NO functions as an inhibitor of crop emptying. This result implied that zymosan stimulates NO production by the induction of iNOS in the digestive tract and thereby inhibits crop emptying rate. However, the co-injection of SMT did not attenuate the inhibitory effect of zymosan on crop emptying. The present study provides evidence that some changes in the digestive tract caused by zymosan are mediated by iNOS-induced NO in chicks, but NO does not mediate the effect of zymosan on feed passage through the crop.