Analysis of patterning in the occurrence of skeletal lesions used as indicators of vitamin D deficiency in subadult and adult skeletal remains.

Paleopathological investigations of conditions linked to vitamin D deficiency have increased in the last twenty years, and a suite of skeletal lesions has been established to aid in the diagnosis of vitamin D deficiency disease in subadults and adults. This paper analyzes the occurrence of these lesions in a large skeletal series comprising 3541 Roman period individuals (1st-6th century AD). Sixteen lesions reported in rickets in subadults, and 13 associated with residual rickets and osteomalacia in adults, were analyzed. Among subadults, there were clear associations among post-cranial lesions. Porotic cranial changes were associated with each other, but not with post-cranial lesions. A range of conditions could have produced the cranial lesions. There was a general paucity of correlations between indicators found in adults, and the difficulty in recording bending deformities was clear. Pseudofractures appear to provide a useful means of investigating osteomalacia in adults. In general, a simple algorithmic approach using presence or absence of lesions is unlikely to provide an adequate means of diagnosing vitamin D deficiency in paleopathology. Knowledge and consideration of the underlying physiological mechanisms involved in lesion formation, combined with individual judgement, will be required to differentially diagnose cases.

Exploratory studies in sensory reinforcement in male rats: effects of methamphetamine.

Understanding sensory reinforcement and the effects of stimulant drugs on sensory reinforcers is potentially important for understanding their influence on addiction processes. Experiment 1 explored the reinforcing properties of a visual stimulus and the effects of methamphetamine (METH) on responding maintained by a visual reinforcer (VRF) in male rats. Snout poke responses to the active alternative produced the VRF according to variable interval (VI) schedules of reinforcement, and responses to an inactive alternative had no programmed effect. Experiment 2 explored the effects of METH on choice between the VRF and a water reinforcer (H2ORF) using concurrent VI schedules in male rats. In Experiment 1, response-contingent onset of the VRF produced an increase in both the relative frequency and absolute rate of active responding. The rate of both active and inactive responding declined across the 40-min test sessions. METH did not differentially enhance active responding for the VRF. Instead, METH nondifferentially increased the rate of responding and attenuated the within-session decline of responding. In Experiment 2, METH differentially increased the rate of responding for the VRF relative to the H2ORF. The results of these exploratory experiments indicate that the reinforcing effects of the VRF were weak and transient. In addition, METH treatment increased responding, and the specificity of the enhancement of METH was dependent upon the testing conditions. Potential explanations of these differences, such as novelty and reinforcer type, are discussed.

Locomotor activity in a novel environment predicts both responding for a visual stimulus and self-administration of a low dose of methamphetamine in rats.

There is evidence that visual stimuli used to signal drug delivery in self-administration procedures have primary reinforcing properties, and that drugs of abuse enhance the reinforcing properties of such stimuli. Here, we explored the relationships between locomotor activity, responding for a visual stimulus, and self-administration of methamphetamine (METH). Rats were classified as high or low responders based on activity levels in a novel locomotor chamber and were subsequently tested for responding to produce a visual stimulus followed by self-administration of a low dose of METH (0.025 mg/kg/infusion) paired with the visual stimulus. High responder rats responded more for the visual stimulus than low responder rats indicating that the visual stimulus was reinforcing and that operant responding for a visual stimulus has commonalities with locomotor activity in a novel environment. Similarly, high responder rats responded more for METH paired with a visual stimulus than low responder rats. Because of the reinforcing properties of the visual stimulus, it was not possible to determine if the rats were responding to produce the visual stimulus, METH or the combination. We speculate that responding to produce sensory reinforcers may be a measure of sensation seeking. These results indicate that visual stimuli have unconditioned reinforcing effects which may have a significant role in acquisition of drug self-administration, a role that is not yet well understood.

Comparaçäo entre a medida do débito cardíaco contínuo com a termodiluiçäo clássica em bolus após cirurgia cardíaca / Comparison of continuous versus bolus cardiac output measurement following valvular surgery

Justificativa e objetivos - a avaliaçäo do débito cardíaco na prática clínica é realizada de forma corrente pelo método de termodiluiçäo. Esta informaçäo é importante, principalmente em pacientes hemodinamicamente instáveis ou em pacientes com doenças cardíacas que väo se submeter a cateterismo cardíaco ou a cirurgia cardíaca. Um novo cateter, com um filamento térmico, permite medir continuamente o débito cardíaco. O objetivo deste estudo foi comparar a medida do débito cardíaco contínuo (DCC) utilizando um cateter na artéria pulmonar, acoplado a um filamento térmico, com o método de medida do débito cardíaco por bolus (DCB) de uma soluçäo fria, no pós-operatório imediato de cirurgia cardíaca para troca valvular. Método - Em vinte e dois pacientes que se submeteram a cirurgia valvular mitral ou aórtica, com circulaçäo extracorpórea hipotérmica, o DCC e DBC, em associaçäo com outros parâmetros hemodinâmicos, foram medidos a cada vinte minutos durante três horas no pós-operatório imediato. Resultados - 198 pares de medidas foram obtidos e comparados. O coeficiente de correlaçä foi de 0,89 (p<0,05). A diferença média do DCB - DCC ñ 0,6 L.min elevado a menos um, e näo foi afetada pela presença de fibrilaçäo atrial. Conclusöes - a comparaçäo destes dois métodos foi satisfatória nestes tipos de pacientes. O DCC aprsenta-se como um método interessante na detecçäo de baixo débito cardíaco imediatamente após cirurgia cardíaca para troca valvular