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Biomedical subjects

J T Harris

Publications and source records attributed to J T Harris.

11 recordsLinked to original sources
PubMed2003

Intravenous morphine for rapid control of severe cancer pain.

This randomized controlled trial compared intravenous route with oral route for initial dose titration of morphine in 62 patients with end-stage cancer and severe pain. Patients in the intravenous group received 1.5 mg intravenous bolus doses of morphine every ten minutes till pain relief was total or until they became drowsy. After that they got oral morphine at a dose equal to the total initial intravenous requirement four-hourly. Patients in the oral group got oral morphine 5 mg doses (if opioid-naïve) or 10 mg (if already on weak opioid) four-hourly. Patients in both groups had the option to receive rescue doses of their regular oral dose as and when needed, if necessary hourly. Twenty-seven of 31 in the intravenous group had either total or satisfactory pain relief by the end of one hour, whereas only eight of 31 in the oral group had a similar result. After 24 hours and later both groups had similar results. There was no immediate serious side effect in any of the patients. The late side effects were similar in the two groups. In the intravenous group, the ratio of initial intravenous dose requirement to the subsequent regular single oral dose after two days centred around 1:1 (range 1:0.5-1:3.3). This study found the intravenous method to be safe, effective and superior to the traditional method in providing immediate relief to severe cancer pain.

Administration, Oral↗
PubMed1999

Transfer of learned information between ganglia in the insect ventral nerve cord.

A yoked control training procedure was used on the decapitated cockroach, L. maderae. The right prothoracic leg was trained to lift in order to avoid a shock. It was found that this information transferred via the two interganglionic connectives from the first or prothoracic ganglion (T1) to the second or mesothoracic ganglion (T2) so that now the right mesothoracic leg lifted to avoid shock even though it was not directly trained. If both connectives were cut before training T1, no transfer to T2 was seen, i.e. the mesothoracic leg did not lift and avoid shock. However, if both connectives were cut immediately after training T1, the information had already transferred and was available for use by T2. There was redundancy in the transfer in that either connective alone could carry the same information from T1 to T2. Either mesothoracic leg could tap into this information. Using a reversible cold block on the connectives, it was found that if it was applied before training T1 it did not interfere with T1 learning but no transfer to T2 was seen after the cold block wore off. That the block was transitory and did not permanently impair the connectives was shown by the fact that if it was applied and then allowed to wear off before training began there was normal learning in T1 and transfer to T2. The transection and cold-block studies were consistent in demonstrating that the transfer of the information was 'on-line' and only occurred during T1 learning. If transfer was blocked during T1 learning the information could not be transferred or tapped into by T2 at a later time even though it was stored in T1 and available for later use by T1. The transfer occurred so quickly it most likely occurred via nerve impulses. Because no primary sensory or motor neurons are in the connectives, the information must have been coded onto interneurones for transfer from the first (T1) to the second (T2) ganglion.

Animals↗
PubMed1993

Maxillary incisor crown-root relationships in different angle malocclusions.

The long axis of the maxillary incisor root is not always identical to that of the crown. Instead, there is appreciable variation in the crown-root angle, generally with the crown torqued lingual to the root axis. In orthodontic cases assessed before and at the end of full-banded treatment, the crown-root angle was significantly deflected in the Class III molar relationship series, notably so in moderate to severe cases where the maxillary incisors are constrained lingual to the lower arcade. Apical root resorption was not significantly associated with the crown-root angle before or after comprehensive orthodontics. Cephalometric predictors of the amount of deflection of the crown-to-root axis were localized to intertooth relationships (overjet, interincisal angle). It is proposed that the large collum angles in Class III cases develop during tooth eruption when the maxillary incisors are trapped within the lower arch; this torques the crown of the maxillary incisor but leaves the unmineralized portion of the root free to develop as if the crown were still in its prior, more procumbent orientation.

Adolescent↗
PubMed1981

The therapeutic effect of amphotericin in acrodermatitis enteropathica: hypothesis and implications.

A nine year-old girl with acrodermatitis enteropathica developed typical clinical and biochemical features of zinc deficiency on two occasions while on an oral zinc supplement. On both occasions, these features responded immediately when she was treated with amphotericin B lozenges. Studies in vitro showed that amphotericin increases the permeability to zinc of pure lipid membranes containing cholesterol. We suggest that the antibiotic enhanced zinc absorption from the oral supplement thereby effecting resolution of the patient's zinc deficiency.

Acrodermatitis↗
PubMedDate not supplied

A ganglionic model of "learned helplessness".

The phenomenon known as "learned helplessness" (LH) is seen broadly across the animal kingdom. Some of the basic characteristics of this behavior are: failure to escape shock when it is possible to do so following non-escapable shock; reversion to non-escape behavior even after successful escape; if the animal is given escape/avoidance training prior to being given inescapable shocks, the latter will not interfere with its ability to later show normal escape/avoidance behavior (generally described as an immunization effect); following inescapable shock training the animals often become "passive and still" when confronted with an inescapable shock. These behaviors are seen in intact mammals, lower vertebrates, and invertebrates. In fact, the basic characteristics are even seen in a spinal rat and, with the exception of one characteristic not yet examined, in an isolated thoracic ganglion of an insect. The brain is evidently not essential either in mammals or in invertebrates for demonstrating this behavior. Not only can an insect ganglion show the behavioral characteristics of LH, but the neural information underlying the phenomenon of LH can be shown to transfer from one ganglion innervating one pair of legs to another ganglion innervating a different pair of legs. Thus, how CNS information underlying LH is coded and transferred from one site to another within the CNS can be examined in such a system. The LH model has provided valuable insights into the physiology of depression. This model suggests that human depression is caused by one's lack of control over traumatic events. It is supported by a number of parallels between depression and LH behavior. Tricyclic antidepressants, MAO inhibitors, and ECT, which are effective in treating depression, also can prevent and reverse LH in mammals. It would be important to find out if they are also effective in invertebrate models. The fact that the characteristics of the behavior called LH are seen in invertebrates such as slugs, cockroaches, and locusts provokes other intriguing questions about the presence of cognition at these phylogenetic levels, as well as what animal or preparation constitutes an appropriate model for human depression.

Animals↗
PubMedDate not supplied

A role for valproate in the treatment of sedative-hypnotic withdrawal and for relapse prevention.

In the human central nervous system, the gamma-aminobutyric acid (GABA) type A receptor complex undergoes changes with both acute and chronic exposure to sedative-hypnotic drugs. These changes contribute to both the acute effects of these drugs as well as the chronic effects of sedative-hypnotic dependence, withdrawal, and drug craving. Clinically these chronic effects are difficult to treat in patients dependent on ethanol or benzodiazepines. Valproate may return the GABA type A receptor function to a state more closely resembling its normal function. By this mechanism, it is possible to reduce the symptoms of sedative-hypnotic withdrawal and relapse.

Chronic Disease↗