Rabbits Of Ages Research Articles

INVESTIGATION OF INFLUENCE OF COAGULATION OF CONVECTION-INFRARED THERMOSURGICAL TECHNOLOGY ON RESECTION LIVER SURFACE (EXPERIMENTAL STUDY)

Introduction. Preclinical study and experience of the use of convection-infrared thermosurgical technology (CITT) confirmed the advantages in providing reliable haemostasis while performing surgery on parenchymatous organs. Aim of the research is to study the features of parenchymal changes of the liver after haemostasis with the use of CITT.Materials and methods. Results of experimental study on 25 outbred rabbits of different gender and age, with the weight of the body from 3350.0 g to 4180.0 g, average weight – 4000.0 g were analysed. The experiment involved resection of liver with coagulation of resection margin using CITT under temperature regimes of 400, 500, 600 0С. Depending on the temperature of coagulation there were formed 3 groups: group 1 – tflow of 4000С; group 2 – tflow of 5000С; group 3 – tflow of 6000С. Data of histologic examination were analysed. Statistical analysis was performed with the help of SPSS Statistics.Results. The study showed that average trend to coagulation layer is 15.76 (13.08-16.64) µm in group 1, 23.88 (21.13-26.40) µm in group 2 and 40.02 (39.09-40.44) µm in group 3 (р=0.001); region of disaggregation/disintegration – group 1-а – 1085.7 (1031.2-1172.3) µm, group 2-а – 753.3 (668-843.8) µm and 470.6 (453.5-507) µm in group 3 (р=0.001). Region of compacted parenchyma: 1622 (1579.5-1664.1) µm in group 1, 2636.6 (2265.4-2906.2) µm in group 2-а (р=0.001).Conclusion. The use of CITT under different temperature regimes demonstrates that the depth of distribution of destructive parenchymal changes of the liver is inversely proportional to the thickness of coagulation layer, which is associated with the features of crust formation and its insulating properties.

Knockout of Apolipoprotein E in rabbit promotes premature intervertebral disc degeneration: A new in vivo model for therapeutic approaches of spinal disc disorders.

Intervertebral disc (IVD) degeneration that accelerates the loss of disc structural and functional integrities is recognized as one of the major factors of chronic back pain. Cardiovascular risk factors, such as deficits of apolipoproteins that elevate the levels of cholesterol and triglycerides, are considered critical for the progress of atherosclerosis; notably in the abdominal aorta and its lumbar branching arteries that supply lumbar vertebrae and IVDs. Obstruction of the lumbar arteries by atherosclerosis is presumed to promote lumbar disc degeneration and low back pain. APOE-knockout rabbits have recently been shown to generate hyperlipidemia with increased levels of cholesterol and triglycerides that mimic the symptoms of atherosclerosis in humans. Here, we analysed IVD degeneration in the lumbar spines of ten homozygous APOE-knockout and four wild-type New Zealand White rabbits of matching age to prove accelerated IVD degeneration in APOE-knockout rabbits, since APOE-knockout rabbits could be a beneficial model for therapeutic approaches of degenerative IVD disorders. Experiments were performed using T1/T2-weighted magnetic resonance imaging, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, glucose-oxidase assay, enzyme-linked immunosorbent assay, quantitative reverse transcription PCR and western blot. APOE-knockout lumbar spines showed more advanced IVD degeneration, obstructed lumbar arteries and lower enhancement of contrast agent in IVDs. Moreover, lower concentration of glucose, lower number of viable cells and lower concentrations of aggrecan, collagen II and higher concentration of collagen I were detected in APOE-knockout IVDs (p < 0.0001). APOE-knockout in rabbits could induce structurally deteriorating premature IVD degeneration that mimics the symptoms of accelerated IVD degeneration in humans. APOE-knockout rabbits could be used as beneficial model, as they can bypass the standard surgical interventions that are commonly applied in research animals for the induction of enhanced IVD degeneration. Their parallel use in therapeutic approaches of IVD disorders and atherosclerosis could reduce the number of research animals to be used and contribute to the principles of 3Rs (Replacement, Reduction and Refinement).

Morphometric parameters of the intestine and aggregated lymphatic nodules of meat rabbits

Nowadays, new breeds of rabbits are appearing with high productivity and rapid growth rate. These breeds require fresh research to be conducted in different fields, which include morphology of the intestine and gut-associated lymphoid tissue (GALT). The morphology of the intestine and GALT of meat rabbits are the investigated objects of the current research. We conducted the investigation on rabbits of different ages (1, 10, 20, 30, 60 and 90 days old). Each age group consisted of five animals. All veterinary ethical requirements were complied with. The body lengths and body masses were measured. Using t-coefficients, we estimated the range of variation of these parameters in each age group. The conclusion about this variation was taken. The masses and lengths of the different intestine parts were investigated as well. Using the obtained values, we provided a continuous numerical model to compute the mass and length of any intestine part of a rabbit of any age in the range from one to 90 days. This allowed us to represent the obtained empirical model by a plot for subsequent detailed study. We found that the changes in masses and lengths do not follow the same pattern for all intestine parts. For some intestine parts, this pattern is approximately linear in the range from one to 90 days; meanwhile for others, the changes in masses and lengths are quite complicated. We observed two local maximas of the growth rate for some intestine parts. Apart from the masses and lengths of the intestine parts, we accomplished macro analysis of the aggregated lymphoid nodules of each age group of animals. We estimated the index of gross area and the law by which it changes in each group. The research results presented here may be used as a basis for composing food ration, assessment of immune status and development of effective prevention and treatment against some diseases.

Pregnancy probabilistically augments potential precursors to chronic, immune-mediated or autoimmune lacrimal gland infiltrates

PurposeThis study asked whether pregnancy, a risk factor for dry eye disease associated with both chronic, immune-mediated- and autoimmune etiologies, augments development of clusters of coordinately functioning cells (CCFC) that may be precursors to pathological lacrimal gland infiltrates. MethodsLacrimal glands were from six virgin- and six term-pregnant rabbits of the same age and environmental exposure history. Seventy-two immune response-related gene transcripts were assayed by real time RT-PCR. Principal component (PC) analysis identified transcript signatures of CCFC contributing negative (⊖) or positive (⊕) PC loadings and determined gland PC projections, which reflect levels of CCFC development. ResultsThree CCFC were of interest as potential precursors to pathological infiltrates. CCFC 1⊖ was suggestive of an ectopic lymphoid structure with resting T cells and B cells. CCFC 1⊕ was suggestive of an immune-mediated infiltrate with TH1 cells and mature, cytotoxic B cells. CCFC 2⊖ was suggestive of an ectopic lymphoid structure with activated T cells, mature B cells, germinal center, and plasmacytes. CCFC 4⊖ and CCFC 5⊖ also included plasmacytes. Pregnancy augmented CCFC 1⊖ in some glands; augmented CCFC 1⊕ in others; and augmented CCFC 2⊖, CCFC 4⊖, and CCFC 5⊖ different combinations. ConclusionsPotential precursors of pathological infiltrates form in the lacrimal glands by the time of sexual maturity. Pregnancy augments lacrimal gland plasmacyte populations, and it can augment development of potential precursors to either chronic, immune-mediated infiltrates or autoimmune infiltrates of various phenotypes. Systemic and strictly local, probabilistic phenomena interact with pregnancy to determine which combinatorial phenotypes are favored.

Changes in three-dimensional muscle structure of rabbit gastrocnemius, flexor digitorum longus, and tibialis anterior during growth

Muscular contraction dynamics depends on active and passive muscle properties (e.g., the force-velocity relation) as well as on the three-dimensional (3D) muscle structure (e.g., the muscle fascicle architecture and aponeurosis dimensions). Much is known about active muscle force generation and the muscle architecture at a particular age (mostly for adult specimens), but less is known about changes in muscle structure during growth. The present study analyzed growth-related changes in the muscle structure of rabbit gastrocnemius lateralis (GL), gastrocnemius medialis (GM), flexor digitorum longus (FDL), and tibialis anterior (TA). Changes in tendon length, muscle belly dimensions (length, width, thickness), as well as aponeurosis length, width, and area were determined using 55 rabbits between 18 and 108 days old. Additionally, the 3D muscle fascicle architecture of five rabbits of different ages (21, 37, 50, 70, 100 days) was determined using a manual digitizer.We found an almost linear increase over time in most of the geometrical parameters observed. GL and GM showed very similar growth characteristics. In contrast to the pronounced increase in muscle belly length of GL and GM, FDL and TA exhibited more uniform muscle belly growth in length, width, and thickness. In general, the aponeuroses of the muscles exhibited lower growth rates in width than in length, and aponeurosis areas were larger than physiological cross-sectional areas. There were almost no changes in fascicle lengths with increasing age for GL, GM, and FDL. In contrast, there was a clear increase in TA fascicle length from about 20 to over 40mm. Pennation angles of TA (11.0 ± 2.1°) and FDL (16.7 ± 3.2°) remained almost unchanged but increased for GL from 13.4 ± 3.3° to 24.3 ± 6.5° from the youngest to the oldest animal. For all muscles observed, the tendon-muscle fascicle length ratio (rTFL) changed during growth. GL and GM exhibited similar increases in rTFL from about 4–8. FDL showed the highest ratio, which increased from about 8–13, whereas TA had the lowest ratio, which decreased slightly from 2 to 1.5.The outcomes demonstrate new findings regarding changes in 3D muscle architecture and aponeurosis shape during growth, and they provide information for muscle force generation, functional relevance, and adaptation with respect to animal age. Therefore, the results help to improve understanding of muscle growth processes and can be used as input data for muscle growth modeling.

MP42-09 ATROGIN IS A NOVEL MARKER OF AGE-RELATED URETHRAL SPHINCTER MUSCLE ATROPHY

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I1 Apr 2017MP42-09 ATROGIN IS A NOVEL MARKER OF AGE-RELATED URETHRAL SPHINCTER MUSCLE ATROPHY M. Raj Rajasekaran, Johnny Fu, My-Uyen (Lilly) Nguyen, and Valmik Bhargava M. Raj RajasekaranM. Raj Rajasekaran More articles by this author , Johnny FuJohnny Fu More articles by this author , My-Uyen (Lilly) NguyenMy-Uyen (Lilly) Nguyen More articles by this author , and Valmik BhargavaValmik Bhargava More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.1298AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Previous studies show an age-related increase in the prevalence of urinary incontinence (UI) (10-15% in adults and ~30% % in older population >70 years). Age-related atrophic changes in urethral sphincter muscles are recognized as the most common cause for UI in the geriatric population. Recently, atrogin (a muscle-specific E3 ubiquitin ligase) is recognized as an important molecular pathway involved in age-related muscle atrophy. We tested the hypothesis that increased urethral sphincter atrophy during advanced aging is mediated by this novel atrogin pathway. METHODS We used a rabbit model to establish time course of age-related urethral sphincter muscle complex dysfunction and for further evaluation of molecular mechanisms of muscle dysfunction /atrophy in rabbits. We employed young (6-9 months), middle age (>12 months) and old rabbits (>30 months) and measured urethral muscle thickness (using transurethral ultrasound (US) technique (Fig A-inset) as well as urethral closure pressure (Fig A) in response to pelvic floor muscle electrical stimulation. We harvested bladder neck (for lissosphincter) and mid-urethra (for rhabdosphincter) samples to evaluate protein and mRNA levels of atrogin (marker of atrophy) using Western blot (protein) /qPCR studies respectively. RESULTS Our rabbit studies confirmed age-related changes in the urethral sphincter muscle thickness (Fig A) and alterations in closure pressure (Fig A) as well as in protein/mRNA levels of marker of atrophy (atrogin; Fig B-D) in both bladder neck and mid-urethra . These observations confirm our hypothesis that age-related increase in atrophy mediated via atrogin pathway may contribute to sphincter muscle dysfunction. CONCLUSIONS Our physiological, imaging and molecular studies are consistent with our hypothesis that age-related increase in atrogin protein contribute to sphincter muscle dysfunction. Targeting atrogin may be a novel approach to prevent age-related urethral sphincter muscle atrophy. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e547 Advertisement Copyright & Permissions© 2017MetricsAuthor Information M. Raj Rajasekaran More articles by this author Johnny Fu More articles by this author My-Uyen (Lilly) Nguyen More articles by this author Valmik Bhargava More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A novel method of standardized myocardial infarction in aged rabbits.

The incidence of both myocardial infarction (MI) and sudden cardiac death increases with age. Here, we describe the development of a minimally invasive large animal model of MI that can be applied to young or aged animals. We demonstrate that rabbit coronary anatomy is highly variable, more so than described in previous literature. In this work, we categorize the coronary pattern of 37 young rabbits and 64 aged rabbits. Aged rabbits had a higher degree of branching from the left main coronary artery. Standardizing the model across age cohorts required a new approach, targeting an area of myocardium rather than a specific vessel. Here, we present a method for achieving a reproducible infarct size, one that yielded a consistent scar encompassing ~30% of the apical left ventricular free wall. The model's consistency allowed for more valid comparisons of MI sequelae between age cohorts.NEW & NOTEWORTHY This study describes the coronary angiographic imaging of young and aged rabbits. We developed and improved a novel minimally invasive approach for coil embolization that targets a specific area of myocardium and yielded a consistent scar encompassing ~30% of the left ventricular free wall of young and aged rabbit hearts.

Glutathione metabolic status in the aged rabbit aorta

It is not known whether aging alters glutathione metabolic status of the mammalian arterial tissue favoring vascular oxidative stress and dysfunction. Thus we assessed total, reduced and oxidized glutathione (TG, GSH and GSSG, respectively), the glutathione redox ratio (GRR, namely [GSSG]/[GSH+2GSSG]×100), and the activities of the glutathione status-regulating enzymes glutathione reductase (GSSG-Red), γ-glutamylcysteine synthetase (γ-GCS) and γ-glutamyl transpeptidase (γ-GT) in the aortic tissue of 9 young adult control rabbits (YACR, about 4months old) and 9 aged rabbits (AR, about 4.5years old); aortic lipid and protein oxidation and H2O2 were also determined as oxidative stress indicators. Vascular function was assessed on aortic ring preparations. TG and GSH concentrations, together with γ-GCS and γ-GT activities, were significantly lower, while GSSG content and the GRR higher, in the AR than in the YACR aortas; GSSG-Red activity did not differ significantly between the two groups. Heightened levels of lipid and protein oxidation and H2O2 occurred in the AR aortas, indicating age-dependent vascular oxidative stress. Moreover, in the whole population of 18 rabbits, the aortic values of GSH and related enzyme activities were inversely and significantly correlated with those of lipid and protein oxidation and H2O2, highlighting the antioxidant role of GSH and related enzymes in the vascular tissue. Aortic endothelium-dependent vasodilation was lower in the AR than in the YACR. In conclusion, glutathione metabolic status is altered in the aged rabbit aorta reflecting depressed γ-GCS- and γ-GT-related GSH biosynthesis and GSSG burden eventually favoring vascular oxidative stress and dysfunction.

Method for organotypic tissue culture in the aged animal

Organotypic slicing of brain tissue from young rodents has been used as a powerful model system for biomedical research [1–3]. Organotypic slicing complements cell culture and in vivo studies in multiple facets. This system can be useful for investigating manipulation of cellular signaling pathways without the hindrance of the blood-brain barrier while sacrificing fewer animals in the process. It also allows for preserved cellular connectivity and local intact circuitry which is a drawback of isolated cell cultures. Studies on age-related diseases have mainly used embryonic or early postnatal organotypic slice tissue. Excluding synaptic plasticity studies that are usually carried-out over a few hours and use adult mice or rats, a handful of studies performed on adult animals have had success for survival of slices [4,5]. Here we describe a method for culturing organotypic slices with high viability from hippocampus of aged mice and rabbits.•Our method permits slices from mice as old as 16 months and rabbits as old as years of age to survive ex vivo up to 8 weeks [6–9]. Such a slice system may be relevant to investigating age-related brain diseases.

14C Miristic acid and 3H cholesterol uptake studies in aging rabbit aorta and heart muscle. The impact of serum factors from patients with lipid metabolic disorders

14C Miristic acid and 3H cholesterol uptake studies in aging rabbit aorta and heart muscle. The impact of serum factors from patients with lipid metabolic disorders

Оценка безопасности применения новой фармацевтической композиции в мягкой лекарственной форме, содержащей антисептик хлоргексидин в комбинации с растительным иммуномодулятором эхинацеей, в эксперименте

&lt;p class="p1"&gt;&lt;span class="s1"&gt;The article presents data on a new pharmaceutical composition developed by the Institute of Organic Synthesis named after I. Postovsky of the Ural Branch of the Russian Academy of Sciences. The composition contains chlorhexidine and semi-solid form echinacea, on the basis of silicone glycerol hydrogel «Silativit». The objective of this study was to assess safety of the new pharmaceutical composition. The study was conducted on white mice (weighing 18-22 g), the population of white rats of Wistar line (weighing 200-260 g), one age group and rabbits of both sexes (weight 2800 g). When determining the acute toxicity there had been no experimental animals deaths recorded the rabbits didn’t appear to have any local irritation or sensibilization within 28 days of the compostion application, therefore one can conclude the new pharmaceutical composition to be safe.&lt;/span&gt;&lt;/p&gt;

RELATIONSHIP AND TREND OF CHANGES ON PARATHYROID HORMONE AND CREATININE LEVEL OF PRENATAL ULTRASOUND INDUCED EXPERIMENTAL SUBJECTS

The aim of this study is to experimentally investigate the effects of prenatal ultrasound exposure on parathyroid hormone and creatinine levels of young rabbit and its trend of changes, and the relationship between parathyroid hormone and creatinine levels of the experimental subjects. A total number of 14 rabbits (Oryctolagus cuniculus) served as the model, where seven pregnant rabbits (treated group) were scanned using ultrasound in the middle of pregnancy for 60 minutes, while another seven pregnant rabbits served as negative control group. After delivery term, the newborns resulted from treatment scheme served as the subject of this study. Blood samples were withdrawn between the ages of 1 month old to five months old and sent to the lab for parathyroid and creatinine level test. The parathyroid hormone (P=0.019) were significantly reduced and no significant difference in creatinine levels (P=0.485). There were significantly reduced PTH in 3 and 5 months old rabbits (P=0.046 and P=0.045, respectively and significantly reduced creatinine level in 2 months old rabbit (P=0.019). Correspondingly, there is no significant linear relationship between parathyroid hormone and creatinine levels (P = 0.835). For trend of changes test, A further long-term study should be taken into consideration to test whether prenatal ultrasound exposure might cause the opposite results in the next generation in young age rabbit.

Age-Related Changes in the Histological Structure of Rabbit Testes and the Prophylactic Role of Vitamin E.

The present investigation is planned to compare between the histological structure of rabbit testes of different ages and the prophylactic role of vitamin E on senescent animals. Male NewZeland rabbits were divided into four groups according to age. Group I: represented the young rabbits (one month age, weighing 1 ± 0.4 kg), group II: adult rabbits (6 months age, weighing 4 ± 0.5 kg), group III: aged animals (24 month age, weighing 7.5 ± 0.5 kg and group (IV) aged rabbits treated daily with the therapeutic dose of vitamin E orally at a dose of 10 mg/kg b.w / day for 60 days. The testes of young rabbits revealed a small form of seminiferous tubules with regular outline with spermatogonia and Sertoli cells, and the lumen appeared empty from spermatozoa. The interstitium is made up of loose connective tissue with large polyhedral interstitial Leydig cells. In adult studied animals, testes demonstrated with all spermatogenic cells and the lumen filled with spermatozoa. In aged rabbits, the histological studies of testis demonstrated atrophied irregular tubules, disarrangement of vacuolated spermatogenic cells, and sloughing of germ cells into the tubular lumen with reduction and degeneration of spermatozoa. The interstitium between the tubules was widen and filled with degenerated and reduced Leydig cells. Administration of vitamin E to aged animals group revealed an obvious improvement of spermatogenic cells, and the spermatozoa appeared in the lumen of many seminiferous tubules.

АКТИВНОСТЬ АСПАРТАТАМИНОТРАНСФЕРАЗЫ В ТКАНЯХ ДВЕНАДЦАТИПЕРСТНОЙ КИШКИ У КРОЛЬЧАТ В РАЗНЫЕ ФАЗЫ ПОСТНАТАЛЬНОГО ОНТОГЕНЕЗА

The purpose of the study is improving different body systems of animals in separate development phases of postnatal ontogenesis. To achieve this goal we studied the patterns of age-related changes of the activity of aspartate aminotransferase in the tissues of the duodenum of rabbits in different phases. Used rabbits breed gray giant at the age 1, 6, 12, 18, 24, 30, 45, 60, 90 and 120 days. The duodenum was divided into three parts: proximal, medial and distal. In every part of the duodenum was isolated two layers: mucous and muscle. In their studies of early postnatal life of rabbits was divided into phases. The studies show that due to changes in the structure and function of the muscular and mucous layers of the mucous membrane of the duodenum, due to changes in the composition and amount of food the activity of the enzyme varies. The activity of AST in the tissues of the mucous and muscle layers of the proximal, medial and distal parts of the duodenum at the age 1 day of rabbits in the colostrum nutrition phase, compared with other age groups, relatively low. In the first six days of life, in colostrum nutrition phase, the enzyme activity increases significantly. To twelve daily age rabbits, in the first dairy feeding phase, the activity of AST also increased significantly. Subsequently, the daily age of eighteen, in the second phase of dairy feeding, the activity of AST decreased significantly in the tissues of both layers ofthe proximal, medial and distal parts of the duodenum. Fromthedailyage of eighteen of rabbits in the tissues mucous layer of the proximal, medial and distal parts and in muscle layer of the distal part of the duodenum, the activity of AST is stabilized. In the muscle layer of the proximal and medial parts of the gut in subsequent phases of feeding rabbits the nature and intensity of age-related changes in activity of AST are slightly different. These distinctive features in the muscle layer of the mentioned parts of the duodenum, possibly associated with peculiarities of generation of their structure. Thus, the most intensive processes of transamination of aminoacids with the participation of aspartate aminotransferase in the examined tissues are seen in rabbits at early stages of postnatal period, toeighteendayold.

ВОЗРАСТНЫЕ ИЗМЕНЕНИЯ АКТИВНОСТИ γ-ГЛУТАМИЛТРАНСФЕРАЗЫ В ТКАНЯХ МЫШЦ КОНЕЧНОСТЕЙ У КРОЛЬЧАТ

The purpose of the study is improvement of various in in animals body systems in separate development phases of postnatal ontogenesis. To achieve this goal, we have studied the regularities of age-related changes in the activity of gamma-glutamyl transferase in the tissues of the muscles biceps and triceps brachii, quadriceps femoris, gluteus and gastrocnemius muscles of the extremities in rabbits in different phases.Used gray giant breed rabbits at the age 1, 6, 12, 18, 24, 30, 45, 60, 90 and 120 days. Age groups were formed according to the principle of unique, taking into account gender, body weight, type of nervous system and general condition. The animal muscle tissue samples were removed and frozen in liquid nitrogen for further research. The activity of gamma glutamyl transferase was determined by photocolorimetric and spectrophotometric methods in the scientific laboratory of the Department of Agricultural Chemistry and Ecology of the Academy. The resalts show the nature of age-related changes of the enzyme levels in the tissues of the biceps and triceps the first forty-five days of life is about the same. But it should be noted that the increase or decrease intensity of GGT activity in the tissues during this lifetime differs. In the rest of the studied periods of life the nature of the activity of the enzyme in the biceps and shoulder triceps is different. The most intensive changes in the GGT level in the tissues of the biceps is detected from two-month to three-month age (increased 2.7 times, p&amp;#60;0.001) in the tissues of the triceps – from forty-five daily to two months (increased 3.9 times) and from three-months to four-months (increased 3.0 times, p&amp;#60;0.001). The character of changes of enzyme activity in the tissues of thigh quadriceps at different age rabbits differs from that of the rest of the studied muscles. The most intensive GGT activity changes from twenty-four to thirty days age (increased 4.0 times, p&amp;#60;0.001). Age-related changes in GGT level in the tissues of the gluteus and calf muscles are basically the same. The difference is found only in the first six days of rabbits&amp;#96; life. Enzyme level in rabbits in the tissues of the gluteus maximus during the first six days increased by 91.0%, p&amp;#60;0.05, and in the tissues of the calf muscle, it falls to 27.3%, p&amp;#60;0.05.

The Role of Mitophagy in Cardiomyocyte Arrhythmogenesis

Aging is associated with more than a ten-fold increase in the incidence of sudden cardiac death. Previously our laboratory published that redox modification of ryanodine receptors (RyR2) by mitochondria-derived reactive oxygen species (ROS) contributes to aberrant calcium handling in cardiomyocytes derived from aging rabbits. However to date, there are no studies that connect increased ROS, mitochondria turnover during aging, and arrhythmia. Here we report that several proteins involved in mitophagy such as p62, LC3II/I, and PINK 1 are down-regulated in the aging rabbit heart. Additionally, we show that the mitochondrial fission protein, DRP1, is increased in the aging rabbit heart. Analysis of the ultra-structure reveals smaller mitochondrion cross-sectional area, fewer mitochondria per square micron, abnormal internal structure, and greater disorganization of the network in aged cardiomyocytes. We therefore hypothesize that decreased mitophagy is a contributing factor that promotes pro-arrhythmic, aberrant calcium signaling through RyR2 activity in aging cardiomyocytes. Blocking mitophagy with chloroquine (1µM) in HL-1 cardiomyocytes under β-adrenergic stimulation (100nM isoproterenol for 5 minutes) resulted in an increase in mitochondria-derived ROS production, upregulation of fission proteins and downregulation of markers of mitophagy. Importantly, we observed increased calcium transient amplitude, increased fractional release, and decreased latency to spontaneous calcium wave formation after 20 seconds of 2.0hz pacing. MitoTEMPO (25μM) reduced ROS production and normalized calcium homeostasis. Our data demonstrate that inhibiting mitophagy in HL-1 cells increases mitochondria derived ROS thereby the hyperactivity of RyR2 and an arrhythmogenic phenotype suggesting that decreased mitophagy contributes to pro-arrhythmic changes in the aging cardiomyocyte.

Effects of replacing groundnut cake with rumen content supplemented with or without enzyme in the diet of weaner rabbits.

BackgroundRabbits are also herbivores which efficiently convert fodder to food. They are prolific and converter of plant proteins of little or no use to people as food into high-value animal protein. Rabbit meat is high in protein, low in calories and low in fat and cholesterol contents, being considered as a delicacy and a healthy food product. Feeding rabbits with concentrates is expensive and therefore in order to reduce cost of production, hence the use of rumen content in this study as alternative feedstuff without competition.MethodsA total of thirty six (36) weaner rabbits (oryctalagus cuniculus) of different body weight and age where use in this experiment to determine the effects of replacing rumen content with or without enzyme supplementation for groundnut cake. This feeding trial which lasted for 8 weeks was carried out in order to determine the replacement value of groundnut cake with rumen content with or without enzyme in the diet of weaner rabbit. A 3x2 factorial experiment was adopted such that there where three (3) replacement level of rumen content (0, 25 and 50 %) for groundnut cake by two supplemental level (no enzyme and enzyme supplement).ResultsThe results showed that increased inclusion level of rumen content has significant effects (p < 0.05) on daily feed intake, rate of weight gain, feed to gain ratio, nitrogen retention, faecal nitrogen, total nitrogen output and nitrogen digestibility. The weight gained by rabbits fed on 0, 25 and 50 % were all comparable (p > 0.05) with weight gained value of 7.62,7.44 and 7.36 g respectively. Similarly there was a significant (p < 0.05) effect of supplement added on the body weight gain of the experimental animals. There was significant effect (p < 0.05) of the diet on the obtained feed to gain ratio. However, there was no significant effect (p > 0.05) of the treatment on urinary nitrogen. Significant (p < 0.05) effects of supplementation was observed on the feed intake, weight gain, feed to gain ratio, faecal nitrogen, nitrogen retention and nitrogen digestibility but there was no significant effects (p > 0.05) of the supplementation on the nitrogen intake. The interaction between the varying levels of rumen content supplementation had significant effects (p < 0.05) on the feacal nitrogen, feed intake and feed to gain ratio but no significant (p < 0.05) effects on interaction of nitrogen intake.ConclusionIn conclusion, since the results from this study showed no negative effects on the performance of the experimental animals, the test ingredient can be used as alternative feedstuff at a lower inclusion level so as to reduce production cost and expand rabbit production.

Attraction and oviposition preferences of Phlebotomus papatasi (Diptera: Psychodidae), vector of Old-World cutaneous leishmaniasis, to larval rearing media.

BackgroundAs part of a project aimed at developing oviposition attractants for the control and surveillance of Phlebotomus papatasi (a vector of Old-World cutaneous leishmaniasis), we tested the hypothesis that gravid sand flies are attracted to chemical cues emanating from the growth medium of conspecific larvae - predominantly larvae-conditioned host feces that represents a suitable oviposition site. We report the results of a systematic assessment of media from various developmental stages of the sand fly using oviposition and olfactometer behavioral assays.MethodsWe conducted multiple-choice oviposition assays in 500 mL Nalgene jars. Six treatments were placed on separate filter paper discs at the bottom of the jar: 2nd/3rd larval instar medium, 4th larval instar/pupae medium, frass from expired colonies, larval food (aged rabbit chow and rabbit feces mix), rabbit feces, and a solvent (water) control. Fifty gravid females were introduced into each jar. Cumulative number of eggs laid on each filter paper per jar was counted at different time intervals from digital images. Attraction of gravid sand flies to these six treatments was assayed with a 3-chamber linear olfactometer. Twenty gravid females were transferred to the middle chamber of the olfactometer and their distribution in treatment and control chambers was recorded after 3 h.ResultsAlmost no eggs were oviposited during the first 72 h following a blood-meal. Cumulative egg deposition increased drastically in the next 24 h (hours 73–96), with a slight non-significant increasing trend thereafter. Comparing mean cumulative egg deposition among the six treatments, we found that significantly more eggs were oviposited on 2nd/3rd larval rearing medium followed by 4th instar/pupae rearing medium. Oviposition preference did not vary over time. The olfactometer results were consistent with the oviposition assays, with 2nd/3rd larval rearing medium being the most attractive, followed by 4th instar/pupae rearing medium.ConclusionThe key finding of this study is that gravid, laboratory reared, Ph. papatasi sand flies are significantly more attracted to rearing medium of the most biologically active larval stages (2nd/3rd instar and 4th instar/pupae). This finding indicates that sand fly-digested host food and feces is attractive to gravid females and suggests that the larvae and larval gut microbiome may be involved in conditioning the oviposition substrate and possibly the production of oviposition attractants and stimulants.

First magenetic resonance imaging studies on aluminium maltolate-treated aged New Zealand rabbits: an Alzheimer's animal model.

Alzheimer's disease is a devastative neurodegenerative disorder. To date, there has been no animal model that could unravel the complete disease pathology. Magnetic resonance imaging has played a pivotal role in the quantitative assessment of brain tissue atrophy for a few decades. In particular, temporal lobe atrophy and ventricular dilatation have been found to be sensitive in Alzheimer's disease. The present study focused on the replication of these crucial pathological events to enable disease progression to be diagnosed at an early stage and stopped through the use of potential therapeutic strategies. The objective of this study was to show temporal lobe atrophy and ventricular dilatation in aluminium maltolate-treated aged New Zealand rabbit, and our study was able to demonstrate this for the first time. The present study makes this animal model a substantial one for further molecular level studies and opens up new targets for potential therapeutic strategies.

Novel cardioprotective strategy combining three different preconditioning methods to prevent ischemia/reperfusion injury in aged hearts in an improved rabbit model.

The use of ischemic preconditioning (IPC) to protect the myocardium is usually not effective in elderly patients. The aim of the present study was to design new methods to achieve enhanced myocardial protection, based on the differential role of endogenous adenosine (ADO) and ADO receptors (ARs) in the effects of IPC on young and old animals. An improved New Zealand white rabbit model of ischemia/reperfusion was established based on the Langendorff model. Adult or elderly rabbit hearts, with or without exposure to IPC, were used in order to assess the roles of ADO and ARs in the different effects of IPC. Different protective methods were designed based on a combination of endogenous and exogenous interventions. Cardiac function, as well as biochemical, histopathological and apoptotic indices, were measured in the different intervention groups. The improved Langendorff model was stable, reliable and suitable for the undertaking of the experiments. The ADO levels in the aged rabbit hearts pre- and post-IPC were lower than those in the adult hearts, indicating that ADO levels may be an endogenous factor influencing IPC. A new protection strategy combining ADO-enhanced IPC, A1AR agonist 2-chloro-N(6)-cyclopentyladenosine preconditioning and cold crystalloid cardioplegia had a significant protective effect in aged hearts. The results of the present study suggested that endogenous ADO enhancement, A1AR agonist preconditioning and exogenous treatment yield an additive effect in aged rabbit hearts. The simultaneous application of these three types of intervention provided the most effective myocardial protection in the improved aged rabbit heart model.