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Biomedical subjects

L Lou

Publications and source records attributed to L Lou.

At least 19 recordsLinked to original sources
PubMed2006

Transhemispheric functional reorganization of the motor cortex induced by the peripheral contralateral nerve transfer to the injured arm.

Peripheral nerve injury in a limb usually causes functional reorganization of the contralateral motor cortex. However, a dynamic process of the novel transhemispheric functional reorganization in the motor cortex was found in adult rats after transferring the seventh cervical nerve root from the contralateral healthy side to the injured limb. Initially the ipsilateral motor cortex activated the injured forepaw for 5 months after the operation. Then, both hemispheres of the cortex activated the injured forepaw, and finally the contralateral cortex exclusively controlled the injured forepaw. It is concluded an extensive functional shift occurred between two hemispheres based on neural plasticity in the CNS. The experimental results of the later lesions of the ipsilateral cortex suggest that maintaining transhemispheric functional reorganization does not depend on the corpus callosum, but depends on mechanisms involving central axonal sprouting. Possible mechanisms underlying the alternative changes in cortical functions were discussed in rats and in patients having similar operations.

Animals↗
PubMed2001

Subdural blood patch for the treatment of persistent CSF leak after permanent intrathecal catheter implantation: a report of two cases.

A CSF leak that persists despite conservative therapy may significantly increase the morbidity associated with implantable intrathecal drug delivery systems. This report presents 2 cases where the application of a subdural blood patch led to the satisfactory resolution of a persistent CSF leak after previous epidural blood patches had failed.

Journal Article↗
PubMed2001

Effects of voluntary attention on structured afterimages.

The effect of voluntary attention on afterimage fragmentation was explored in two experiments. The afterimage, in the form of a 30 degrees-tilted star of David, was generated after prolonged steady fixation in the first experiment, and with a brief and intense flash in the second experiment. Subjects were instructed to select various target shapes in the afterimage for attention and, at the same time, observe what was visible or invisible. Verbal reports and manual responses to afterimage changes were analyzed. Attended shapes were found to disappear from awareness Faster than unattended ones (experiment 1), and complementary shapes were found to predominate visual awareness when one of the pair was selected for attention (experiment 2). Voluntary attention was also found to affect closure (filling-in of enclosed regions) and smoothing of line figures in afterimages.

Attention↗
PubMed2001

[Luminescence dependence upon concentration and temperature in YPO4:Pr3+].

Under selective excitation 3P0 state of Pr3+ ion in YPO4, the emission spectra and fluorescence decay curves are measured at different concentrations and temperatures. The origin of the spectral line located at 613.2 nm has been discussed and assigned to be the 1D2 (gamma 3)-->3H4 (gamma 5) transition. The different concentration dependence of emission intensities of levels 3P0 and 1D2 has been studied. Using static model, the fluorescence decay curve of 1D2 level is fitted, and the result shows that the cross-relaxation caused by the interaction of dipole-quadrupole between adjacent Pr3+ ions results in the concentration quenching.

Attention↗
PubMed2000

Uncommon areas of electrical stimulation for pain relief.

Uncommon stimulation refers to the use of peripheral nerve and spinal cord stimulation for nontraditional applications. There has been much interest recently with subcutaneous suboccipital stimulation for occipital neuralgia, sacral stimulation for pelvic pain, trigeminal stimulation for trigeminal neuralgia, and spinal cord stimulation for angina and peripheral ischemia. The indications and techniques used for accomplishing each method are discussed.

Electric Stimulation Therapy↗
PubMed2000

Mechanisms of speed-accuracy tradeoff: evidence from covert motor processes.

Speed-accuracy tradeoff (SAT) refers to the inverse relation between speed and accuracy found in many tasks. The present study employed reaction times (RTs) and movement-related brain potentials arising during the RT interval (lateralized readiness potentials; LRPs) to examine the mechanisms by which people control their position along an SAT continuum. Many models of SAT postulate that changes in position across conditions (macro-tradeoffs) and trial-by-trial variations within conditions (micro-tradeoffs) are mediated, at least in part, by the same mechanisms. These include: (1) all models that postulate mixtures of guesses and accurate responses and (2) some models postulating decision criterions applied to accumulating evidence or response tendencies. Such models would seem to be rejected for conditions under which macro- and micro-tradeoffs can be shown to involve no stages of RT in common. Under the present conditions, the two types of SAT produced additive effects on RT, with the macro-tradeoff involving only that portion of the RT interval occurring after LRP onset and the micro-tradeoff involving only that portion before LRP onset. These findings imply that the two types of SAT arose during different serial stages of RT and that the macro-tradeoff involved only stages occurring after differential preparation of the two hands had begun.

Brain↗
PubMed2000

Clinical guidelines for intraspinal infusion: report of an expert panel. PolyAnalgesic Consensus Conference 2000.

Consensus guidelines developed by an expert panel are helpful to clinicians when there is variation in practice and lack of a firm evidence base for an intervention, such as intraspinal therapy for pain. An internet-based survey of practitioners revealed remarkable variation in practice patterns surrounding intraspinal therapy. This prompted an interdisciplinary panel with extensive clinical experience in intraspinal infusion therapy to evaluate the results of the survey, the systematic reviews of the literature pertaining to this approach, and their own clinical experience with long-term spinal infusions. The panel proposed a scheme for the selection of drugs and doses for intraspinal therapy, and suggested guidelines for administration that would increase the likelihood of a successful outcome. These expert panel guidelines were designed to provide an initial structure for clinical decision making that is based on the best available evidence and the perspectives of experienced clinicians.

Analgesics↗
PubMed2000

Evidence-based review of the literature on intrathecal delivery of pain medication.

Evidence-based medicine depends on the existence of controlled clinical trials that establish the safety and efficacy of specific therapeutic techniques. Many interventions in clinical practice have achieved widespread acceptance despite little evidence to support them in the scientific literature; the critical appraisal of these interventions based on accumulating experience is a goal of medicine. To clarify the current state of knowledge concerning the use of various drugs for intraspinal infusion in pain management, an expert panel conducted a thorough review of the published literature. The exhaustive review included 5 different groups of compounds, with morphine and bupivacaine yielding the most citations in the literature. The need for additional large published controlled studies was highlighted by this review, especially for promising agents that have been shown to be safe and efficacious in recent clinical studies.

Analgesics↗
PubMed1999

The Development of a Technique for Radiofrequency Lesioning of Splanchnic Nerves.

This article describes the development of a technique for radiofrequency lesioning of the splanchnic nerves. It features point neurolysis and improvement in safety from previously described techniques with the use of a curved, blunt needle. After extensive anatomic studies, the site of entry has been identified 4 cm lateral to the spinous process at the costovertebral angle of either the T11 or T12 vertebral body, and the placement of the needle tip at the junction of posterior two thirds to the anterior one third of the vertebral body. The use of a sharp, straight needle has been discouraged to prevent pneumothorax, and bowel, kidney, or nerve root injury. The radiofrequency lesion permits a point neurolysis, thus decreasing the rate of complications. Our experience of 22 patients treated with this technique has been complication-free, and the outcome was effective for all 10 patients with cancer. In the nonmalignancy group, some patients needed a second neurolysis (radiofrequency) procedure 4 months apart. There were also no secondary complications in these patients. We expect multicenter data accumulation in the coming years, which will determine the true efficacy of the radiofrequency of splanchnic nerves.

Journal Article↗
PubMed1999

Novel Drug Delivery Systems.

Interest in pain management is growing, with the emerging demand by our patients and colleagues, for pain relief. To meet that need, pharmaceutical and medical technology companies have provided the medical field with a variety of choices and options to deliver medication for pain control. Examination and review of the present systemic options are introduced. A more detailed look at the intrathecal route is necessary because of the tremendous potential for receptor-targeted drug delivery. The ability to treat nociceptive and neuropathic pain with drug-specific therapy makes this system all the more exciting. Because of this future, a wealth of new and old drugs are being found or reexamined for their use.

Journal Article↗
PubMed1999

Effects of a hair cell transcription factor, Brn-3.1, gene deletion on homozygous and heterozygous mouse cochleas in adulthood and aging.

The transcription factor Brn-3.1, is expressed in the inner ear hair cells throughout life and is necessary for the development of these cells. Mutant mice in which the Brn-3.1 encoding region has been deleted have no identifiable hair cells, greatly reduced numbers of spiral ganglion cells and are deaf. A mutation in the human homologue of this gene has been shown to be related to adult onset, sensorineural hearing loss (Vahava et al., 1998). The question whether haploinsufficiency in the mutant Brn-3.1 mouse with a mixed C57BL6/129Sv genetic background could affect the adult or aged cochlea was tested, therefore, by measuring the auditory brainstem responses and examining the cochlea's histologically at 2, 18 and 24 months of age. The heterozygotes had a comparable hearing to the wild-type animals and similar patterns of cochlear degeneration. Both groups showed an about 30 dB hearing loss beginning at 18 months of age, outer hair cell degeneration and loss of spiral ganglion neurons in the basal turn. There appeared to be no effect of Brn-3.1 haploinsufficiency on the mouse cochlea, implying that one intact copy of the gene is sufficient to maintain a normal cochlea.

Aging↗
PubMed1999

Selective peripheral fading: evidence for inhibitory sensory effect of attention.

A circular array of six discs, three green and three orange in alternate positions, was presented against a uniform grey background. Sixteen observers maintained steady fixation at the centre of the array, and were instructed to direct their attention to three discs of one colour and to ignore the three discs of the other colour. In about 10 s (mean = 11.35 s), some discs started to fade away from awareness. Of those starting to fade, most (mean = 81.3%) were those selected for attention. The faded discs remained out of awareness for up to a few seconds (mean = 1.55 s) during which other discs were clearly visible. The fading increased with eccentricity, a defining characteristic of Troxler fading. However, the selectivity of the fading strongly suggests that voluntary attention can have an inhibitory effect on early sensory processing. Were the fading entirely due to local sensory adaptation, the unattended stimuli would have to be equally adapted and yet somehow remain visible for seconds, which is not plausible.

Color Perception↗
PubMed1999

Modulation of Ca2+/calmodulin-dependent protein kinase II activity by acute and chronic morphine administration in rat hippocampus: differential regulation of alpha and beta isoforms.

Calcium/calmodulin-dependent protein kinase II (CaMK II) has been shown to be involved in the regulation of opioid receptor signaling. The present study showed that acute morphine treatment significantly increased both Ca2+/calmodulin-independent and Ca2+/calmodulin-dependent activities of CaMK II in the rat hippocampus, with little alteration in the protein level of either alpha or beta isoform of CaMK II. However, chronic morphine treatment, by which rats were observed to develop apparent tolerance to morphine, significantly down-regulated both Ca2+/calmodulin-independent and Ca2+/calmodulin-dependent activities of CaMK II and differentially regulated the expression of alpha and beta isoforms of CaMK II at protein and mRNA levels. Application of naloxone or discontinuation of morphine treatment after chronic morphine administration, which induced the withdrawal syndrome of morphine, resulted in the overshoot of CaMK II (at both protein and mRNA levels) and its kinase activity. The phenomena of overshoot were mainly observed in the beta isoform of CaMK II but not in the alpha isoform. The effects of both acute and chronic morphine treatments on CaMK II could be completely abolished by the concomitant application of naloxone, indicating that the effects of morphine were achieved through activation of opioid receptors. Our data demonstrated that both acute and chronic morphine treatments could effectively modulate the activity and the expression of CaMK II in the hippocampus.

Analgesics, Opioid↗
PubMed1999

[Cloning whole length cDNA of related genes responsible for smooth muscle cells proliferation in atherogenesis and study on its function].

OBJECTIVE: To clone whole length cDNA of the related genes responsible for vascular smooth muscle cell (SMC) proliferation in atherogenesis, and to study its function. METHODS: ox-LDL was added as a stimulant to the SMC culture medium. Subtractive library was established using subtractive hybridization technique in order to clone the related genes fragments. With the whole length cDNA library established, the whole length cDNA of the related gene was cloned. The protein expressed was studied. RESULTS: 4 new gene fragments and one whole length cDNA were cloned. The new cloned gene is able to express a protein of about 44000 daltons and closely related to the activity of ox-LDL. CONCLUSIONS: The new cloned gene is considered responsible for SMC proliferation.

Arteriosclerosis↗
PubMed1999

[Plasma Lp (a) levels and correlation of Lp (a) with fibrinolysis activation in chronic renal failure].

Plasma Lp (a) concentration and activation of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1(PAI-1) were determined in 50 patients with chronic renal failure (CRF) and in 50 healthy subjects. The results demonstrated that plasma concentration of Lp(a) was significantly higher and plasma t-PA activation was significantly lower in CRF patients than in healthy subjects. With multivariate analyses, plasma Lp(a) concentration was positively correlated with the total amount of 24 h uric protein, plasma BUN and uric protein concentration. Moreover, a negative significant correlation between plasma Lp(a) levels and t-PA activation was observed. Plasma Lp(a) levels did not show a correlation to PAI-1 activation. It is indicated that renal function may contribute to moderate plasma Lp(a) concentration and elevated Lp(a) levels may be related with fibrinolytic impairment.

Adult↗