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1.
J Anim Sci ; 95(12): 5327-5338, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29293749

RESUMEN

The objectives of this study were 1) to determine if supplementation of zilpaterol hydrochloride (ZH) altered select organ weights, histology, and cardiac anatomical features at harvest and 2) to determine if administration of a corticotropin-releasing hormone (CRH) and vasopressin (VP) challenge following 20 d of ZH supplementation altered the blood chemistry profile in cattle. Crossbred heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), without ZH, and 2) zilpaterol (ZIL; ZH at 8.33 mg/kg [DM basis] for 20 d). On d 20 of supplementation, heifers were fitted with indwelling jugular catheters. On d 24, starting at 0800 h and continuing until 1600 h, blood samples were collected at 60-min intervals. At 1000 h, heifers received an i.v. bolus of CRH (0.3 µg/kg BW) and VP (1.0 µg/kg BW) to activate the stress axis. Serum was separated and stored at -80°C until analyzed for a large-animal chemistry panel. Following the CRH/VP challenge, heifers were harvested on d 25, 26, and 27 (5, 6, and 7 d after ZH supplementation); BW, HCW, select organ weights, and histology were measured, and a total heart necropsy was performed. A treatment effect ( ≤ 0.02) was observed for Ca, K, creatinine, alkaline phosphatase, and sorbitol dehydrogenase. Zilpaterol-fed heifers had decreased ( ≤ 0.02) concentrations of Ca and K and increased concentrations ( 0.01) of creatinine ( = 0.02) during the CRH/VP challenge when compared to control heifers. Control heifers had greater ( ≤ 0.05) alkaline phosphatase and sorbitol dehydrogenase concentrations when compared with ZIL heifers. A treatment × time interaction ( = 0.02) was observed for P; concentrations were similar between treatments from -2 to 6 h postchallenge, and 7 h postchallenge CON heifers had decreased P. Liver ( = 0.06) and kidney ( = 0.08) weights as a percentage of BW tended ( ≤ 0.08) to be reduced in ZIL heifers. Gross liver weights tended ( = 0.08) to be lower in ZIL heifers. Other organ (heart, lung, adrenals) to BW ratios remained similar ( ≥ 0.41). These data suggest that there are some variations observed between treatments in terms of response to ZH supplementation and the CRH/VP challenge; however, in the environmental conditions of this study, limited variation in blood metabolic responses and organ weights suggests that the supplementation of ZH did not detrimentally alter the physiology of cattle.


Asunto(s)
Bovinos/fisiología , Hormona Liberadora de Corticotropina/farmacología , Suplementos Dietéticos , Compuestos de Trimetilsililo/metabolismo , Vasopresinas/farmacología , Animales , Análisis Químico de la Sangre/veterinaria , Composición Corporal/efectos de los fármacos , Bovinos/sangre , Dieta/veterinaria , Femenino , Tamaño de los Órganos/efectos de los fármacos , Distribución Aleatoria
2.
J Anim Sci ; 94(7): 2798-810, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27482667

RESUMEN

The objective of this study was to determine the metabolic, stress, and hematology response of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to an endocrine stress challenge. Heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), no ZH supplementation, and 2) zilpaterol (ZIL), supplemented with ZH at 8.33 mg/kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of corticotropin-releasing hormone (CRH; 0.3 µg/kg BW) and arginine vasopressin (VP; 1.0 µg/kg BW) to activate the stress axis. Blood samples were collected at 30-min intervals for serum and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge at 0 h (1000 h). Samples were analyzed for glucose, insulin, NEFA, blood urea nitrogen (BUN), cortisol, epinephrine, norepinephrine, and complete blood cell counts. Following the challenge, cattle were harvested over a 3-d period. Liver, LM, and biceps femoris (BF) samples were collected and analyzed for glucose, lactate, and glycolytic potential (GP). There was a treatment ( ≤ 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1°C decrease in VT when compared with CON. A treatment × time effect ( = 0.002) was observed for NEFA. A treatment effect was observed for BUN; ZIL had decreased BUN concentrations compared with CON ( < 0.001) prior to the challenge; however, no treatment × time effect was observed. There was also a treatment effect for cortisol ( ≤ 0.01) and epinephrine ( = 0.003); ZIL had decreased cortisol and epinephrine during the CRH/VP challenge when compared with CON. There was a time effect for total white blood cells, lymphocytes, and monocytes; each variable increased ( ≤ 0.01) 2 h postchallenge. Additionally, neutrophil counts decreased ( ≤ 0.01) in response to CRH/VP challenge in both treatment groups. Glucose concentrations within the LM were greater ( = 0.03) in CON when compared with ZIL. Lactate concentrations and GP within the BF were greater in CON ( = 0.05) when compared with ZIL. These data suggest there are some variations observed between treatments in terms of response to the CRH/VP challenge; however, in the environmental conditions of this trial, none of the variations observed suggest that the supplementation of ZH detrimentally alters the ability of cattle to effectively respond to stressful stimuli.


Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Bovinos/fisiología , Suplementos Dietéticos , Hormonas/administración & dosificación , Compuestos de Trimetilsililo/farmacología , Animales , Recuento de Células Sanguíneas/veterinaria , Glucemia/análisis , Nitrógeno de la Urea Sanguínea , Hormona Liberadora de Corticotropina/administración & dosificación , Dieta/veterinaria , Femenino , Músculos Isquiosurales/efectos de los fármacos , Músculos Isquiosurales/metabolismo , Hematología , Insulina/sangre , Estrés Fisiológico/efectos de los fármacos , Vasopresinas/administración & dosificación
3.
Clin Neurophysiol ; 113(4): 519-27, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11955996

RESUMEN

OBJECTIVES: To determine whether the process responsible for the mismatch negativity (MMN) might be involved in the analysis of temporal sound patterns for information. METHODS: Synthesized musical instrument tones of 'clarinet' timbre were delivered in a continuous sequence at 16 tones/s, such that there was virtually no N1 potential to each individual tone. The standard sequence comprised 4 or 5 adjacent notes of the diatonic scale, presented either as a regularly repeated, rising pattern or pseudo-randomly. The deviant stimuli were 1-5 consecutive tones of higher pitch than the standards. RESULTS: A MMN was evoked by a single deviant tone, 1 or 5 semitones above the pitch range of the standards. The response to the 5-semitone deviant was significantly larger (mean of 7.3 microV) when the standard pattern was regular as compared with pseudo-random. The MMN latency, on the other hand, was only influenced by the magnitude of pitch deviation. A second MMN was evoked by a second deviant tone, immediately (SOA 62.5 ms) following the first. Further consecutive MMNs were not consistently evoked. CONCLUSIONS: The large amplitude of these MMNs can be attributed to the use of complex tones, continuous presentation and a rapid rate of pitch changes, such that no waveform subtraction was required. Over and above the probability with which each individual tone occurs in the standard sequence, the mismatch process is influenced by its temporal structure, i.e. can be regarded as a temporal pattern analyzer. Contrary to the findings of some other groups, we found that two consecutive deviants can evoke an MMN, even at high rates of presentation such that both occur within the postulated 'temporal window of integration' of ca. 170 ms. These findings suggest that the mismatch process might be involved in the extraction of sequential information from repetitive and non-repetitive sound patterns.


Asunto(s)
Estimulación Acústica/estadística & datos numéricos , Potenciales Evocados Auditivos/fisiología , Percepción de la Altura Tonal/fisiología , Estimulación Acústica/métodos , Adulto , Análisis de Varianza , Femenino , Humanos , Masculino , Persona de Mediana Edad , Distribución Aleatoria
4.
Exp Brain Res ; 140(1): 56-65, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11500798

RESUMEN

The object of the study was to look for a neurophysiological substrate of sequential auditory stream segregation. When a sequence of tones alternates rapidly between pitches separated by more than a few semitones, there is a tendency for it to be perceived as two independent "streams". We examined the scalp potentials evoked when the pitch interval abruptly changes, to see whether there are response parameters which might be correlated with sudden stream segregation and/or integration. For 3 s a continuous synthesized tone of "clarinet" timbre oscillated between pitches of F4 and F#4 (one semitone higher) at 16 notes/s, perceived as an integrated stream. The upper note was then raised to E5 (11 semitones above F4, perceived as segregated streams) for a further 3 s and the cycle was repeated 40 times. In a second condition also starting with oscillation between F4 and F#4, the upper note was lowered to E4 (one semitone below F4, still perceived as a single stream). Further conditions examined the changes between oscillations of 1 and 11 semitones down from E5, 1 and 23 semitones up from F4, and 10 and 11 semitones up from F4. Virtually no potentials were detectable during the periods of unchanging oscillation, but an N1/P2 complex was evoked on each change in the pitch interval. The N1 was termed "MN1" on account of its arguable relatedness to the mismatch negativity, recorded in a separate experiment using discontinuous tones at a much slower rate. The mean peak latency of the MN1 varied between 96 and 123 ms, the shortest latencies being recorded, not to the largest changes of pitch interval but to the widest pitch intervals between the new tone and the immediately preceding one. Therefore, although a causal relationship with streaming cannot necessarily be inferred, the MN1 latency appears to mark the degree of pitch contrast between consecutive tones, in correlation with the streaming effect.


Asunto(s)
Electroencefalografía/métodos , Potenciales Evocados Auditivos/fisiología , Percepción de la Altura Tonal/fisiología , Cuero Cabelludo/fisiología , Estimulación Acústica/métodos , Adulto , Audiometría , Encéfalo/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tiempo de Reacción/fisiología
5.
Clin Neurophysiol ; 111(9): 1569-76, 2000 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10964066

RESUMEN

OBJECTIVES: To examine whether two cortical processes concerned with spectro-temporal analysis of complex tones, a 'C-process' generating CN1 and CP2 potentials at cf. 100 and 180 ms after sudden change of pitch or timbre, and an 'M-process' generating MN1 and MP2 potentials of similar latency at the sudden cessation of repeated changes, are dependent on accumulation of a sound image in the long auditory store. METHODS: The durations of steady (440 Hz) and rapidly oscillating (440-494 Hz, 16 changes/s) pitch of a synthesized 'clarinet' tone were reciprocally varied between 0.5 and 4.5 s within a duty cycle of 5 s. Potentials were recorded at the beginning and end of the period of oscillation in 10 non-attending normal subjects. RESULTS: The CN1 at the beginning of pitch oscillation and the MN1 at the end were both strongly influenced by the duration of the immediately preceding stimulus pattern, mean amplitudes being 3-4 times larger after 4.5 s as compared with 0.5 s. CONCLUSIONS: The processes responsible for both CN1 and MN1 are influenced by the duration of the preceding sound pattern over a period comparable to that of the 'echoic memory' or long auditory store. The store therefore appears to occupy a key position in spectro-temporal sound analysis. The C-process is concerned with the spectral structure of complex sounds, and may therefore reflect the 'grouping' of frequency components underlying auditory stream segregation. The M-process (mismatch negativity) is concerned with the temporal sound structure, and may play an important role in the extraction of information from sequential sounds.


Asunto(s)
Encéfalo/fisiología , Potenciales Evocados Auditivos/fisiología , Estimulación Acústica , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tiempo de Reacción/fisiología
8.
Electroencephalogr Clin Neurophysiol ; 108(4): 355-60, 1998 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-9714377

RESUMEN

Auditory evoked potentials were recorded to onset and offset of synthesised instrumental tones in 40 normal subjects, 20 right-handed for writing and 20 left-handed. The majority of both groups showed a T-complex which was larger at the right temporal electrode (T4) than the left (T3). In the T4-T3 difference waveforms, the mean potential between latencies of 130 and 165 ms was negative in all right-handed subjects except two for whom the waveforms were marginally positive-going. Amongst the left-handers, however, this converse asymmetry was seen in 7 subjects, 5 of them more than 2 standard deviations from the mean of the right-handed group. The degree of asymmetry was not significantly correlated with the degree of left-handedness according to the Edinburgh Handedness Inventory. Asymmetry of the T-complex to instrumental tones appears to reflect the lateralisation of auditory 'musical' processing in the temporal cortex, confirming evidence from other sources including PET that this is predominantly right-sided in the majority of individuals. The proportion of left-handers showing the converse laterality is roughly in accordance with those likely to be right-hemisphere-dominant for language. If linguistic and 'musical' processes are consistently located in opposite hemispheres, AEPs to complex tones may prove a useful tool in establishing functional lateralisation.


Asunto(s)
Dominancia Cerebral/fisiología , Potenciales Evocados Auditivos/fisiología , Lateralidad Funcional/fisiología , Música , Estimulación Acústica/métodos , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tiempo de Reacción/fisiología , Valores de Referencia
9.
Tissue Cell ; 29(2): 207-15, 1997 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9149443

RESUMEN

The objective of this experiment was to determine the growth characteristics of bovine embryonic muscle cells and to optimize the growth conditions for these cells using commercially-prepared media and sera. In the first study, the growth of muscle cells isolated from the hindlimb was determined by measuring DNA content. The DNA concentration was lowest (P < 0.001) at 24 h post-plating and increased to a maximum at approximately 60 h. The slopes of creatine kinase activity and fusion index curves were similar to the DNA; however, the creatine kinase activity achieved a maximum at 140 h post-plating, while the fusion index reached maximum at 120 h. In the second study, cells were cultured on different substrata, either plastic, gelatin, or collagen. There were no differences (P > 0.05) in the cell growth rates for any of the three substrata. In the third study, cells were grown in 10% fetal bovine serum (FBS) and either a balanced salt solution (BSS; 30 mM Hepes, 10 mM glucose, 120 mM NaCl, 2.5 mM Na2HPO4, and 3 mM KCl), McCoy's 5A, Dulbecco's Minimal Essential Medium/Ham's F12 (DMEM/F12), or 70% DMEM/20% M-199. Cell numbers adhering to the plate at 26 h post-plating were different (P > 0.001) between each medium (DMEM/M-199 > McCoy's 5A > DMEM/F12 > BSS). Cell proliferation rates for each treatment medium were greatest for DMEM/M-199, followed by McCoy's 5A, DMEM/F12, and BSS. Cell differentiation was highest (P < 0.05) in the DMEM/F12, followed by McCoy's 5A, DMEM/M-199, and BSS. In the final study, the cells were treated with different sources of serum added at 10% to DMEM/M-199. The sera consisted of FBS, newborn calf serum (NCS), horse serum (HS) and iron-supplemented calf serum (Fe(2+)-CS). The cells were added to each well at 10(4) cells. At 24 h post-plating, the serum-free, NCS, and FBS-treated cell numbers were greater (P < 0.05) than the cells treated with HS or Fe(2+)-CS, which may reflect the efficient adherence to the surface or faster adaptation to the serum by the cells. The proliferation rate was greatest (P < 0.001) for the cells treated with Fe(2+)-CS, followed by FBS = NCS, HS, and no serum. Therefore, the muscle cells obtained from bovine embryos grow and differentiate similar to muscle cells from other species. The optimal growth medium for growing these cells in vitro is DMEM/M-199 plus 10% Fe(2+)-CS, while the optimal differentiation medium is McCoy's 5A.


Asunto(s)
Técnicas de Cultivo de Célula/métodos , Feto/citología , Fibras Musculares Esqueléticas/citología , Animales , Bovinos , Recuento de Células , Diferenciación Celular/fisiología , División Celular/efectos de los fármacos , División Celular/fisiología , Células Cultivadas/citología , Células Cultivadas/efectos de los fármacos , Células Cultivadas/enzimología , Creatina Quinasa/metabolismo , Medios de Cultivo/farmacología , Fibras Musculares Esqueléticas/enzimología , Músculo Esquelético/citología , Músculo Esquelético/embriología , Músculo Esquelético/enzimología
10.
J Anim Sci ; 72(1): 68-74, 1994 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-7511137

RESUMEN

Forty-eight crossbred rabbits were used in three replications of a 2 x 4 factorial arrangement to investigate the short-term responses of tissue accretion, calpains and calpastatin activity, and nucleic acid and protein concentrations to beta-adrenergic agonist (BAA) feeding. Rabbits were fed a 17% CP diet with or without 7 ppm of L644,969 and slaughtered after 1, 4, 8, or 16 d of treatment. Empty body dressing percentage and biceps femoris weight (as a percentage of empty body weight [EBW]) were significantly higher in the treated rabbits than in the controls after 16 d of treatment. Heart and liver weights (as a percentage of EBW) were higher (P < .05) after 1 d and liver weight (as a percentage of EBW) was lower (P < .05) after 16 d in treated vs controls. Except for an elevation of skeletal muscle m-calpain after 16 d, BAA-supplementation did not affect the calpain-calpastatin system. Muscle RNA concentrations and RNA:DNA ratios were higher (P < .05) in treated rabbits after 1 d and remained higher thereafter. Protein:RNA ratios were lower (P < .01) in treated than in control rabbits after 4 d and remained lower throughout the trial. Muscle DNA content was lower after 4 d and higher after 16 d; RNA content was higher after 4, 8, and 16 d; and protein content was higher after 16 d in treated vs control rabbits. Liver nucleic acid and protein concentrations were not affected by BAA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Proteínas de Unión al Calcio/metabolismo , Calpaína/metabolismo , Piridinas/farmacología , Conejos/crecimiento & desarrollo , Animales , Nitrógeno de la Urea Sanguínea , Calpaína/antagonistas & inhibidores , ADN/análisis , Femenino , Corazón/efectos de los fármacos , Corazón/crecimiento & desarrollo , Hígado/química , Hígado/efectos de los fármacos , Hígado/crecimiento & desarrollo , Desarrollo de Músculos , Proteínas Musculares/análisis , Músculos/química , Músculos/efectos de los fármacos , Miocardio/química , Tamaño de los Órganos/efectos de los fármacos , ARN/análisis , Conejos/metabolismo
11.
J Anim Sci ; 71(3): 636-44, 1993 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-7681817

RESUMEN

Forty wether lambs were used in a 2 x 4 factorial arrangement to determine the response of animal performance, muscle growth, proteinase activity, and meat tenderness to beta-adrenergic agonist (BAA) supplementation. Lambs were fed a finishing diet with or without 4 ppm of L644,969 and slaughtered after 0, 2, 4, and 6 wk of treatment. The ADG was higher (P < .05) in the treated than in the control lambs after 2 wk and returned to control levels thereafter. Semitendinosus weight and calpastatin activity were higher and mu-calpain activity was lower in the treated than in the control lambs after 2, 4, and 6 wk. Cathepsin B activity was higher (P < .01) and cystatin-like activity was lower (P < .05) after 2 wk in treated than in control lambs but returned to control levels thereafter. Longissimus protein:DNA was higher after 4 (P < .05) and 6 (P < .01) wk in the treated lambs than in the controls. The concentration of RNA and RNA:DNA ratio were higher (P < .01) in the longissimus and semitendinosus muscles in the treated lambs after 2 wk and remained higher throughout the study. Semitendinosus protein and RNA content were higher after 2, 4, and 6 wk and DNA content was higher after 2 and 6 wk in the treated than in the control lambs. Longissimus shear-force values were higher (P < .001) in the treated than in the control lambs at all slaughter end points. These data indicate a rapid alteration of muscle growth, activity of the calpain-calpastatin system, and meat tenderness during BAA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Carne/normas , Músculos/efectos de los fármacos , Piridinas/farmacología , Ovinos/crecimiento & desarrollo , Envejecimiento/fisiología , Alimentación Animal , Animales , Proteínas de Unión al Calcio/metabolismo , Calpaína/antagonistas & inhibidores , Calpaína/metabolismo , Catepsinas/metabolismo , Cistatinas/metabolismo , ADN/análisis , Endopeptidasas/metabolismo , Masculino , Desarrollo de Músculos , Proteínas Musculares/análisis , Músculos/química , Músculos/enzimología , ARN/análisis , Distribución Aleatoria , Ovinos/metabolismo , Aumento de Peso/efectos de los fármacos
12.
Artículo en Inglés | MEDLINE | ID: mdl-1372229

RESUMEN

Long latency auditory evoked potentials (AEPs), chiefly consisting of a negative peak at about 150 msec and a positivity at 250 msec, were recorded at the beginning and end of periods during which the interaural time difference of binaural noise was switched between 0.0 and 0.8 msec at a fast rate (ISI = 50 or 25 msec) or the frequency of continuous binaural clicks was switched between 167 and 200 Hz every 80, 50 or 25 msec. In the latter case the offset responses occurred later than onset by a mean of 89, 47 and 27 msec respectively, suggesting they were probably generated at the moment the next switch was expected but failed to occur. The offset responses must be non-specific with respect to the interaural delay or the frequency of clicks, since neurones which respond to particular delays or frequencies and are made refractory by a rapid rate of stimulation should not suddenly become less so at the last in a series of identical stimuli, or be activated by the absence of a further event. It is proposed that the potentials are due to a higher order of neurone which automatically responds to the occurrence of a "mismatch" between the immediate sound and an image of that which was previously present, encoded in a short-term sensory store. In addition to frequency content and interaural delay, the image must contain information about the temporal modulation pattern of the sound over the previous few seconds.


Asunto(s)
Potenciales Evocados Auditivos/fisiología , Memoria/fisiología , Estimulación Acústica , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Tiempo de Reacción/fisiología
13.
Artículo en Inglés | MEDLINE | ID: mdl-1716565

RESUMEN

When non-identical binaural noise signals suddenly become coherent in the two ears, or coherent noise suddenly becomes incoherent, long latency binaurally evoked potentials (BINEP) are elicited which consist of P70, N130 and P220 components. Responses of similar morphology and latency were recorded to a change in the frequency of monaural click trains. The responses to onset or offset of the click trains were 20-50 msec shorter in latency. BINEP are also evoked when the sound image suddenly shifts due to the introduction of a short inter-aural delay in coherent noise signals. Responses to "isolated" shifts occurring once every 7 sec were 2-3 times (N130) or 3-5 times (P220) larger than responses to "frequent" shifts (6/7 sec) of the same magnitude in the same direction. Responses to "infrequent" shifts (1/7 sec) interspersed with frequent shifts in the opposite direction were of intermediate size, significantly larger than frequent responses. The BINEP could reflect the activity of location-specific neurones in the auditory cortex, but it seems more likely that they are due to a common neuronal pool responsive to any shift in the location of the sound image. Similar neuronal pools may be concerned with the detection of change in other auditory dimensions such as pitch. The difference between isolated, infrequent and frequent responses suggests that the BINEP amplitude is dependent on a memory of the shifts which have occurred in the preceding few seconds. The underlying process may be similar or identical to that which governs generation of the "mismatch negativity."


Asunto(s)
Percepción Auditiva/fisiología , Electroencefalografía , Potenciales Evocados Auditivos/fisiología , Audición/fisiología , Memoria/fisiología , Estimulación Acústica , Adulto , Femenino , Humanos , Masculino
14.
Artículo en Inglés | MEDLINE | ID: mdl-1707806

RESUMEN

When uncorrelated random noise signals presented to the two ears suddenly become identical (coherent), a centrally located sound image is abruptly perceived and long latency scalp potentials are evoked. When the same signals are presented monaurally there is no perceived change and no potentials are evoked: hence the response must be purely a function of the binaural interaction. P70, N130 and P220 components were consistently recorded to both coherence and discoherence. N130 was usually largest at Fz and P220 at Cz. No potentials of shorter latency were identified, even after averaging 5000 or more sweeps. When the noise became coherent with an inter-aural time difference (delta T) of +/- 0.5 msec (giving rise to an off-centre sound image), the responses were of slightly longer latency and showed no significant asymmetries between C3 and C4. In binaurally coherent noise, delta T changes of +/- 0.5 or +/- 1.0 msec evoked similar responses which showed no significant asymmetries on the scalp. N130 was of longer latency when delta T was changed from +/- 0.5 msec to zero, as compared with the converse change. In view of the similarity of all these responses it is considered unlikely that they were due to specific populations of binaurally responsive cortical neurones. The N130 and P220 components are thought to be non-specific potentials which are elicited by any perceptible change in steady auditory stimulus conditions, due to a "mismatch" between the stimulus and the contents of a short-term auditory memory.


Asunto(s)
Potenciales Evocados Auditivos/fisiología , Cuero Cabelludo/fisiología , Estimulación Acústica , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Tiempo de Reacción
15.
Scan Electron Microsc ; (Pt 3): 1259-71, 1985.
Artículo en Inglés | MEDLINE | ID: mdl-2416039

RESUMEN

The present studies relate to the single or isolated osteoclastic resorption function assay which we introduced in 1983 to overcome objections to assays based upon measurements of calcium release from bones, in which it was never strictly controlled whether the mechanism involved the destruction of bone with the formation of classical Howship's lacunae. The method may prove to be quite popular in the near future and has already been adopted by other research groups. In previous work, we had utilised stereophotogrammetry of scanning electron micrographs to measure the depth, volume and other parameters of the individual lacunae. However, increasing experience with the method has suggested that we can await a wide range of biological variability in single cell function in any one experiment. We have therefore tested other methods from which data could be obtained more rapidly to permit a better statistical analysis, albeit with reduced accuracy, of each resorption complex. The main aim of the studies reported here was to evaluate various methods of optical and scanning electron microscopy that can be used for the visualization of osteoclasts and their associated resorption lacunae generated in vitro in slabs of dentine and bone. Optical microscopy was found to be complementary to SEM, enabling vital microscopy of unstained and stained cells. In particular, oblique illumination LM and tandem scanning reflected LM (TSRLM) proved to be of paramount value for this purpose. Fixed coated specimens could be most rapidly scanned for resorption lacunae using darkfield reflected LM or TSRLM.


Asunto(s)
Microscopía Electrónica de Rastreo/métodos , Osteoclastos/ultraestructura , Resorción Dentaria/patología , Animales , Huesos/metabolismo , Embrión de Pollo , Dentina/ultraestructura , Humanos , Microscopía Fluorescente , Microscopía de Interferencia , Conejos , Ratas , Coloración y Etiquetado , Ballenas
16.
Electroencephalogr Clin Neurophysiol ; 43(6): 853-63, 1977 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-73453

RESUMEN

Short latency evoked potentials were recorded from sites overlying the cervical and thoracic vertebrae, the clavicles, mastoid processes and cerebral cortex, following percutaneous stimulation of median nerve fibres at the elbow, wrist and fingers in 23 normal subjects. At least four major early components each with simultaneous positive and negative constituents, plus the first component (N20) of the cortical response, were all found to be mediated by sensory afferent fibres with conduction velocity 65--75 m/sec in the forearm of one subject. Study of the distribution of these potentials, using reference electrodes located at Fz or over the lower part of the spine, has led to the proposal of generator sites in the brachial plexus (N9), spinal roots or dorsal columns (N11), spinal grey matter or brain stem (N13), and brain stem or thalamus (N14). Comparison with intrathecal recordings in man lends support to the view that N11 and N13 are generated in or adjacent to the spinal cord. It is hoped the findings may extend the clinical applications of a non-invasive technique for investigating the afferent sensory pathways in man.


Asunto(s)
Electroencefalografía , Nervio Mediano/fisiología , Cuello/inervación , Cuero Cabelludo/inervación , Adulto , Vías Aferentes/fisiología , Plexo Braquial/fisiología , Tronco Encefálico/fisiología , Potenciales Evocados , Femenino , Humanos , Masculino , Conducción Nerviosa , Tiempo de Reacción , Piel/inervación , Médula Espinal/fisiología , Raíces Nerviosas Espinales/fisiología , Tálamo/fisiología
17.
Cell Tissue Res ; 166(1): 65-70, 1976 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-1248039

RESUMEN

Embryonic and young rat bone cells have been growing in culture and examined in the scanning electron microscopy (SEM). Compared with cells fixed in situ and taken directly from the animal, the cultured osteoblastic cells were smoother, flatter and more extensive and showed tighter intercellular contacts. Some matrix is formed in culture and undergoes at least partial mineralization as judged by the accumulation of Ca and P measured by energy dispersive x-ray analysis. Findings concerning the morphology of the collagen arrangement were indecisive. Some superficial cells, free of surrounding matrix, resembled osteocytes in normal in vivo bone. This may indicate that a proportion of the extracellular matrix produced by the cultured cells failed to polymerise into recognizable bone matrix, and that osteocytic morphology is not dependent upon the physical characteristics of the bone matrix.


Asunto(s)
Huesos/ultraestructura , Animales , Matriz Ósea/análisis , Matriz Ósea/ultraestructura , Calcificación Fisiológica , Calcio/análisis , Diferenciación Celular , Células Cultivadas , Colágeno , Fibroblastos/ultraestructura , Técnicas In Vitro , Uniones Intercelulares/ultraestructura , Microscopía Electrónica de Rastreo , Osteoblastos/ultraestructura , Osteocitos/ultraestructura , Fósforo/análisis , Ratas
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