RESUMEN
Beef from cattle finished on grass will be of similar quality to that from cattle finished on grain when their carcasses are processed using best practice protocols. To test this hypothesis, carcasses of twenty Brahman steers, finished to 400 kg live weight on either Buffel grass pasture (n=10) or grain (n=10), were electrically stimulated with 400 V for 50 s 45 min postmortem, and their beef quality assessed 1 and 14 days postmortem. Hot weight, rump subcutaneous fat thickness and animal rate of growth in the 205 days preceding slaughter were recorded for each carcass as potential influences on beef quality. Quality of the M. longissimus thoracis (LT) at 1 and 14 days postmortem was evaluated using peak Warner-Bratzler shear force, compression, pH, cooking loss and taste panel acceptability, as well as by moisture and crude fat contents measured at 1 day postmortem. Results showed that steers finished on pasture grew the slowest and had the least subcutaneous fat at the same carcass weight. LT from carcasses of steers finished on pasture also had the shortest mean sarcomere lengths, suggesting these muscles may have been cold-affected, but there was no effect of diet on peak shear force. LT from carcasses of steers finished on pasture had the highest mean compression value, possibly because of increased collagen cross-linking associated with slow growth or increased exercise. Ageing significantly decreased LT peak shear force and compression values and increased cooking loss, L (∗), a (∗) and b (∗) values. Taste panellists rated the aged, grass-finished beef the most tender and the best quality; however, the taste panel in this study may have favoured LT from grass-finished steers because it was significantly juicier than LT from the grain-finished steer carcasses. These results indicated that carcass composition and processing conditions interact to exert a greater effect on LT toughness and sensory acceptability than finishing diet. Ageing LT from steers finished on grass improved its colour, and thus may enhance its consumer acceptability.
RESUMEN
Stress-induced levels of plasma glucocorticoid hormones are known to modulate leukocyte function. These experiments examined the effects of a social stressor on the responsiveness of peripheral immune cells. Male mice experienced six evening cycles of social disruption (SDR), in which an aggressive male intruder was placed into their home cage for 2 h. Although circulating corticosterone was elevated in SDR mice, they had enlarged spleens and increased numbers of splenic leukocytes. Splenocytes from SDR and control mice were cultured with lipopolysaccharide and corticosterone. Cells from SDR mice exhibited decreased sensitivity to the antiproliferative effects of corticosterone, suggesting that the peripheral immune cells were resistant to glucocorticoids. In addition, SDR cells produced more interleukin (IL)-6. To determine which cell population was affected, we used antibody-labeled magnetic beads to deplete splenocyte suspensions of B cells or macrophages. Depletion of macrophages from SDR cultures, but not depletion of B cells, abolished both the corticosterone resistance and enhanced IL-6 secretion. These findings demonstrate that a psychosocial stressor induced glucocorticoid resistance in mouse splenic macrophages.
Asunto(s)
Agresión , Corticosterona/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/fisiología , Medio Social , Estrés Psicológico/fisiopatología , Animales , División Celular/efectos de los fármacos , Corticosterona/fisiología , Resistencia a Medicamentos , Interleucina-6/biosíntesis , Recuento de Leucocitos , Leucocitos/patología , Lipopolisacáridos/farmacología , Macrófagos/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Valores de Referencia , Bazo/efectos de los fármacos , Bazo/patologíaRESUMEN
Introducing an aggressive intruder into a cage of mice (social disruption, SDR) resulted in intense fighting and defeat of the cage residents. Defeat was accompanied by elevated levels of serum corticosterone and nerve growth factor (NGF). Repeated exposure to an intruder induced a state of glucocorticoid resistance in peripheral immune cells. The present study sought to examine the behavioral factors that mediated the development of glucocorticoid resistance following SDR. Glucocorticoid resistance developed in animals that exhibited a subordinate behavioral profile, which consisted of a low tendency for social investigation and a high level of submissive behavior in response to the intruder's attacks. Glucocorticoid resistance was also linked to the presence of injuries due to fighting, but not to changes in systemic levels of either corticosterone or NGF. Since a submissive behavioral profile is associated with increased risk for injuries due to fighting, it may be that the development of glucocorticoid resistance is an adaptive mechanism that allows the inflammatory component of wound healing to occur in the presence of high levels of corticosterone. Together, these findings demonstrate that the outcomes of social stress may be modified by physiological changes associated with wounding, as well as by behavioral variables such as social status.
Asunto(s)
Dominación-Subordinación , Glucocorticoides/farmacología , Relaciones Interpersonales , Estrés Psicológico/fisiopatología , Animales , Conducta Animal/fisiología , Mordeduras y Picaduras/fisiopatología , Corticosterona/farmacología , Resistencia a Medicamentos/fisiología , Jerarquia Social , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
The influence of social disruption stress (SDR) on the susceptibility to endotoxic shock was investigated. SDR was found to increase the mortality of mice when they were challenged with the bacterial endotoxin lipopolysaccharide (LPS). Histological examination of SDR animals after LPS injection revealed widespread disseminated intravascular coagulation in the brain and lung, extensive meningitis in the brain, severe hemorrhage in the lung, necrosis in the liver, and lymphoid hyperplasia in the spleen, indicating inflammatory organ damage. In situ hybridization histochemical analysis showed that the expression of the glucocorticoid receptor mRNA was down-regulated in the brain and spleen of SDR animals while the ratio of expression of AVP/CRH-the two adrenocorticotropic hormone secretagogue, increased. After LPS injection, the expression of pro-inflammatory cytokines, IL-1beta and TNF-alpha, was found significantly higher in the lung, liver, spleen, and brain of the SDR mice as compared with the LPS-injected home cage control animals. Taken together, these results show that SDR stress increases the susceptibility to endotoxic shock and suggest that the development of glucocorticoid resistance and increased production of pro-inflammatory cytokines are the mechanisms for this behavior-induced susceptibility to endotoxic shock.
Asunto(s)
Susceptibilidad a Enfermedades/fisiopatología , Choque Séptico/fisiopatología , Conducta Social , Estrés Fisiológico/fisiopatología , Animales , División Celular/efectos de los fármacos , Separación Celular , Corticosterona/sangre , Corticosterona/farmacología , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades/etiología , Susceptibilidad a Enfermedades/inmunología , Relación Dosis-Respuesta a Droga , Inmunocompetencia/efectos de los fármacos , Inmunocompetencia/inmunología , Interleucina-1/genética , Interleucina-1/metabolismo , Lipopolisacáridos , Masculino , Ratones , Ratones Endogámicos C57BL , Especificidad de Órganos , ARN Mensajero/metabolismo , Receptores de Glucocorticoides/biosíntesis , Receptores de Glucocorticoides/genética , Choque Séptico/inducido químicamente , Choque Séptico/inmunología , Bazo/citología , Bazo/efectos de los fármacos , Bazo/inmunología , Bazo/metabolismo , Estrés Fisiológico/sangre , Estrés Fisiológico/inmunología , Tasa de Supervivencia , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Glucocorticoid (cort) responses have been shown to suppress inflammatory reactions by inhibiting the trafficking of immune cells. Recently, it was demonstrated that restraint stress (RST) and psychosocial stress (social reorganization; SRO) differentially affected the pathophysiology and survival in the mouse influenza viral infection model. While both stressors activated the HPA axis, only SRO affected survival. In RST, elevated cort diminished recruitment of inflammatory cells following intranasal challenge of C57BL/6 mice with A/PR8 virus. However, infected SRO mice developed hypercellularity in the lungs and were more likely to die from lung consolidation than controls. Since elevated cort failed to be anti-inflammatory in SRO mice, the hypothesis that psychosocial stress induced steroid insensitivity was tested. An in vitro cort suppression test was performed by stimulating splenocytes from SRO and control mice with mitogen in the presence or absence of cort. Proliferation of ConA-stimulated cells was inhibited by cort in a dose-dependent fashion in controls, but splenocytes from SRO mice stimulated with ConA were resistant to cort-induced suppression. Thus, psychosocial stress induced a state of steroid insensitivity. SRO also induced the release of nerve growth factor (NGF) from the salivary glands into circulation; plasma NGF correlated with development of steroid insensitivity. NGF has been reported to negatively regulate the expression of type II glucocorticoid receptors, and thus may be a key factor in the induction of steroid insensitivity.
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Glucocorticoides/inmunología , Factor de Crecimiento Nervioso/inmunología , Estrés Psicológico/inmunología , Virosis/inmunología , Animales , Susceptibilidad a Enfermedades/inmunología , Femenino , Inmunidad , Masculino , Ratones , Ratones Endogámicos C57BL , Virosis/etiologíaRESUMEN
A series of novel platinum(IV) cisplatin analogues of the type [Pt(cis-1,4-DACH)trans-(L)2Cl2] (where cis-1,4-DACH = cis-1,4-diaminocyclohexane and L = acetate, propionate, butyrate, valerate, hexanoate, heptanoate, octanoate, nonanoate, or decanoate) was synthesized and characterized by elemental analysis, IR, 13C-NMR, and 195Pt-NMR spectroscopy. The structure of [Pt(cis-1,4-DACH)trans-(acetate)2Cl2] (1) was determined by X-ray crystallography. The crystals were monoclinic, space group P2(1)/n (no. 14) with a = 10.193(2), b = 10.687(2), c = 14.265(3) A, beta = 99.67(3) degrees, Z = 4. The total reflections collected were 2556. The structure refinement converged to R1 = 0.0539 and wR2 = 0.1531. In this complex, platinum has distorted octahedral geometry, and cis-1,4-DACH is in a unique twist-boat configuration. cis-1,4-DACH forms a seven-member chelating ring with platinum, leading to considerable strain in bidentate DACH binding. The strain is evidenced by a large 126.5(9) degrees C-N-Pt angle. The N-Pt-N angle is expanded to 97.4(5) degrees owing to geometric constraints of the cis-1,4-DACH geometry. Three lower homologs of the cis-1,4-DACH-Pt(IV) series were tested in the murine L1210/0 leukemia model for antitumor activity. The results indicate that activity decreases in ascending the homologous series, and that the activity of two of the complexes is substantially better than that of cisplatin with respect to increase in life span and cures.
Asunto(s)
Antineoplásicos/síntesis química , Antineoplásicos/uso terapéutico , Compuestos Organoplatinos/síntesis química , Compuestos Organoplatinos/uso terapéutico , Animales , Antineoplásicos/química , Cristalografía por Rayos X , Leucemia L1210/tratamiento farmacológico , Espectroscopía de Resonancia Magnética , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Modelos Químicos , Modelos Moleculares , Compuestos Organoplatinos/químicaRESUMEN
We investigated the retrograde axonal transport of 125I-labeled neurotrophins (NGF, BDNF, NT-3, and NT-4) from the sciatic nerve to dorsal root ganglion (DRG) sensory neurons and spinal motor neurons in normal rats or after neuronal injury. DRG neurons showed increased transport of all neurotrophins following crush injury to the sciatic nerve. This was maximal 1 day after sciatic nerve crush and returned to control levels after 7 days. 125I-BDNF transport from sciatic nerve was elevated with injection either proximal to the lesion or directly into the crush site and after transection of the dorsal roots. All neurotrophin transport was receptor-mediated and consistent with neurotrophin binding to the low-affinity neurotrophin receptor (LNR) or Trk receptors. However, transport of 125I-labeled wheat germ agglutinin also increased 1 day after sciatic nerve crush, showing that increased uptake and transport is a generalized response to injury in DRG sensory neurons. Spinal cord motor neurons also showed increased neurotrophin transport following sciatic nerve injury, although this was maximal after 3 days. The transport of 125I-NGF depended on the expression of LNR by injured motor neurons, as demonstrated by competition experiments with unlabeled neurotrophins. The absence of TrkA in normal motor neurons or after axotomy was confirmed by immunostaining and in situ hybridization. Thus, increased transport of neurotrophic factors after neuronal injury is due to multiple receptor-mediated mechanisms including general increases in axonal transport capacity.
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Transporte Axonal/fisiología , Factores de Crecimiento Nervioso/metabolismo , Neuronas/fisiología , Receptores de Superficie Celular/fisiología , Médula Espinal/fisiología , Animales , Axotomía , Transporte Biológico Activo/fisiología , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Masculino , Neuronas Motoras/fisiología , Compresión Nerviosa , Neuronas Aferentes/fisiología , Ratas , Ratas Sprague-Dawley , Rizotomía , Nervio Ciático/fisiología , Médula Espinal/citologíaRESUMEN
The receptor tyrosine kinase, MuSK, is required for the formation of the neuromuscular junction (NMJ) where MuSK becomes phosphorylated when exposed to neuronally synthesized isoforms of agrin. To understand better the mechanisms by which MuSK mediates the formation of the NMJ, we have examined how MuSK expression is regulated during development in the embryo, by neuromuscular injury in the adult and by agrin in vitro. Here we show that MuSK is associated with the earliest observable AChR clusters at the developing motor endplate and that MuSK and AChRs codistribute throughout the development of the NMJ. These two proteins are also coordinately regulated on the surfaces of cultured myotubes where MuSK and AChRs colocalize both in spontaneous and agrin-induced clusters. While MuSK is normally restricted to the motor endplate in adult muscle, denervation results in its extrajunctional expression, although a discernible concentration of MuSK remains localized to the motor endplate even 14 days after denervation. Extrajunctional MuSK is first apparent 3 days after denervation and is sharply reduced upon reinnervation. Muscle paralysis also markedly alters the expression of MuSK in adult muscle and results in increased expression of MuSK as well as increased transcription of MuSK mRNA by extrasynaptic myonuclei. Together, these findings demonstrate that MuSK expression is highly regulated by innervation, muscle activity, and agrin, while the distribution of MuSK is precisely coordinated with that of the AChR.
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Unión Neuromuscular/enzimología , Proteínas Tirosina Quinasas Receptoras/metabolismo , Agrina/farmacología , Animales , Células Cultivadas , Desnervación , Masculino , Ratones , Placa Motora/embriología , Placa Motora/enzimología , Contracción Muscular/fisiología , Unión Neuromuscular/efectos de los fármacos , Unión Neuromuscular/embriología , Parálisis/enzimología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Proteínas Tirosina Quinasas Receptoras/genética , Receptores Colinérgicos/metabolismoRESUMEN
Despite the widespread use of polypeptide growth factors as pharmacological agents, little is known about the extent to which these molecules regulate their cognate cell surface receptors and signal transduction pathways in vivo. We have addressed this issue with respect to the neurotrophic molecule ciliary neurotrophic factor (CNTF). Administration of CNTF in vivo resulted in modest decreases in levels of CNTFRalpha mRNA and protein in skeletal muscle. CNTF causes the rapid tyrosine phosphorylation of LIFRbeta and gp130 and the induction of the immediate-early gene, tis11; injection of CNTF 3-7 h after an initial exposure failed to re-stimulate these immediate-early responses, suggesting a biochemical desensitization to CNTF not accounted for by decreased receptor protein. To determine whether the desensitization of immediate-early responses caused by CNTF resulted in a functional desensitization, we compared the efficacy of multiple daily injections versus a single daily dose of CNTF in preventing the denervation-induced atrophy of skeletal muscle. Surprisingly, injections of CNTF every 6 h, which falls within the putative refractory period for biochemical responses, resulted in efficacy equal to or greater than injections once daily. These results suggest that although much of the CNTF signal transduction machinery is down-regulated with frequent CNTF dosing, biological signals continue to be recognized and interpreted by the cell.
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Proteínas de Unión al ADN , Regulación hacia Abajo , Proteínas Inmediatas-Precoces , Proteínas del Tejido Nervioso/farmacología , Receptores de Factor de Crecimiento Nervioso/metabolismo , Transducción de Señal , Animales , Factor Neurotrófico Ciliar , Relación Dosis-Respuesta a Droga , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , Proteínas/administración & dosificación , Proteínas/farmacología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptor de Factor Neurotrófico Ciliar , Transducción de Señal/efectos de los fármacos , TristetraprolinaRESUMEN
We discuss two different ways of measuring outcome in a sample of 20 patients who had intracranial aneurysm surgery. Patients were evaluated at discharge using the Karnofsky Scale and the Glasgow Outcome Scale. Six months after discharge we conducted a neuropsychiatric evaluation including cognitive, behavioral, and mood status assessment. Although 13 of our patients had a "good recovery', 18 had some neuropsychiatric impairment. We did not find statistical relationships between the discharge evaluation and the neuropsychiatric assessment at follow-up. We discuss the need for developing new outcome measures to pick-up neuropsychiatric deficits, beyond the traditional neurologic semiology.
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Aneurisma Intracraneal/cirugía , Adulto , Femenino , Humanos , Aneurisma Intracraneal/fisiopatología , Aneurisma Intracraneal/psicología , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Pronóstico , Escalas de Valoración PsiquiátricaRESUMEN
BACKGROUND: With the reduction of mortality and gross neurologic morbidity of patients undergoing intracranial aneurysm surgery, the interest in outcome is shifting towards more subtle aspects such as cognitive deficits and psychosocial adjustment. METHODS: We discuss two different ways of measuring outcome in a sample of 20 patients who had intracranial aneurysm surgery. Patients were evaluated at discharge using the Karnofsky Scale and the Glasgow Outcome Scale. Six months after discharge we conducted a neuropsychiatric evaluation including cognitive, behavioral, and mood status assessment. RESULTS: Although 13 of out patients had a "good recovery, " 18 had some neuropsychiatric impairment. Comparing patients with "good recovery" with the remainder, patients with poorer outcomes tended to have a left pterional approach, a poorer "drive", and language disorders (p < 0.05). There was no correlation between out cognitive, mood, and behavioral assessment and the results of the Karnofsky and Glasgow Outcome Scales ( p > 0.05). CONCLUSIONS: we conclude that neuropsychiatric deficits are common after intracranial aneurysm surgery and that for our study the Karnofsky Scale and Glasgow Outcome Scale were not sensitive enough to detect residual impairment. therefore, it is important to develop brief tests and scales able to identify these problems and to complement the standard clinical neurological examination.
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Aneurisma Intracraneal/psicología , Adulto , Femenino , Estudios de Seguimiento , Humanos , Aneurisma Intracraneal/cirugía , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Periodo Posoperatorio , Resultado del TratamientoRESUMEN
This is the first report on the meat quality and carcass composition of farmed blackbuck antelope (Antilope cervicapra). Seventeen animals comprising entire males aged 7-10 months, entire males aged 13-16 months, and castrated males aged 13-16 months of age were raised on improved pastures, herded (one man plus a dog) into yards, transported 63 km and slaughtered in a commercial abattoir. Carcasses were Tenderstretched (hung by the pelvis allowing the hind legs to drop). Castration reduced liveweight gain but had no effect on carcass weight. All carcasses were very lean with mean separable fat ranging from 0.3% in 13-16 month entires to 3.5% in castrates of the same age. Primal cuts composition was similar for all three groups except that the castrates had a proportionately less developed neck and a proportionately heavier brisket than either group of entire males. Mean ultimate pH for each of four muscles (aged LD, unaged LD, aged ST, aged BF) from each treatment group ranged between 5.47 and 5.75. The meat was very tender, with mean Warner Bratzler initial yield values between 1.3 and 3.4 kg, and mean Warner Bratzler peak force values between 2 and 4.5kg. There was a tendency for the meat from 13-16 month entires to be leaner, have higher ultimate pH, and be slightly less tender than that of the other two groups. It was concluded that farmed blackbuck antelope can produce meat of high objective quality and that castration is useful as a management strategy.
RESUMEN
While a number of growth factors have been described that are highly specific for particular cell lineages, neither a factor nor a receptor uniquely specific to the skeletal muscle lineage has previously been described. Here we identify a receptor tyrosine kinase (RTK) specific to skeletal muscle, which we term "MuSK" for muscle-specific kinase. MuSK is expressed at low levels in proliferating myoblasts and is induced upon differentiation and fusion. In the embryo, it is specifically expressed in early myotomes and developing muscle. MuSK is then dramatically down-regulated in mature muscle, where it remains prominent only at the neuromuscular junction; MuSK is thus the only known RTK that localizes to the neuromuscular junction. Strikingly, MuSK expression is dramatically induced throughout the adult myofiber after denervation, block of electrical activity, or physical immobilization. In humans, MuSK maps to chromosome 9q31.3-32, which overlaps with the region reported to contain the Fukuyama muscular dystrophy mutation. Identification of MuSK introduces a novel receptor-factor system that seems sure to play an important and selective role in many aspects of skeletal muscle development and function.
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Músculo Esquelético/embriología , Músculo Esquelético/enzimología , Unión Neuromuscular/enzimología , Proteínas Tirosina Quinasas Receptoras/metabolismo , Secuencia de Aminoácidos , Animales , Northern Blotting , Mapeo Cromosómico , Cromosomas Humanos Par 9 , Clonación Molecular , Secuencia Conservada , Expresión Génica , Humanos , Ratones , Datos de Secuencia Molecular , Desnervación Muscular , Reacción en Cadena de la Polimerasa , ARN Mensajero/biosíntesis , Ratas , Proteínas Tirosina Quinasas Receptoras/química , Proteínas Tirosina Quinasas Receptoras/genética , Receptores Colinérgicos/análisis , Sinapsis/enzimologíaRESUMEN
The receptor mechanisms mediating the retrograde axonal transport of the neurotrophins have been investigated in adult rats. We show that transport of the TrkB ligands NT-4 and BDNF to peripheral neurons is dependent on the low affinity neurotrophin receptor (LNR). Pharmacological manipulation of LNR in vivo using either an anti-LNR antibody or a soluble recombinant LNR extracellular domain completely blocked retrograde transport of NT-4 and BDNF to sensory neurons, while having minimal effects on the transport of NGF in either sensory or sympathetic neurons. Furthermore, in mice with a null mutation of LNR, the transport of NT-4 and BDNF, but not NGF, was dramatically reduced. These observations demonstrate a selective role for LNR in retrograde transport of the various neurotrophins from distinct target regions in vivo.