SEARCH · PubMed Health

Results for “Deep Learning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources

PubMed1975

Phleborheographic technique for diagnosing deep venous thrombosis of the lower extremities.

There has been further experience with a new plethysmographic technique for diagnosing deep venous thrombosis of the lower extremity. Now called phleborheography, this technique is highly practical and noninvasive and can be conveniently performed in the laboratory, at the bedside or in the office of the physician by a technician. Interpretation of the permanent tracing may be learned by a physician in a short period of time. Since development of a new specifically designed instrument, the accuracy of the test is approximately 96 per cent when correlatewith phlebography.

Chronic Disease↗

PubMed1989

Risk factors for heterotopic ossification in spinal cord injury.

Heterotopic ossification (HO) is a complication in 16% to 53% of spinal cord injured (SCI) patients. One third of these patients have moderate to severe HO that adversely affects function or health. Pharmacologic prophylaxis of HO for all SCI patients continues to be controversial. High-risk criteria for HO formation identified in total hip replacement patients are not applicable to SCI. A review of the literature did not reveal specific risk factors for HO with SCI. The charts of 100 randomly selected SCI patients, 50 with HO and 50 without HO, were reviewed retrospectively to learn if criteria which would predict high-risk patients could be identified. A total of 14 variables, seven demographic (age, sex, race, level of lesion, completeness of lesion, cause of injury, and geographic locus of patient) and seven medical (bladder stones, fractures, pressure sores, deep vein thrombosis, pulmonary embolism, spasticity, and urinary tract infections) were studied. Four of the 14 variables (age, completeness of lesion, presence of pressure sores, and spasticity) were significantly related to HO formation. The risk factors appear to be additive. When all were present, 92% of patients were found to have HO. Before the findings are applied clinically, it is suggested that a prospective study be conducted to confirm the risk predictive value of these factors in HO.

Adult↗

PubMed2005

Proposed mechanism for learning and memory erasure in a white-noise-driven sleeping cortex.

Understanding the structure and purpose of sleep remains one of the grand challenges of neurobiology. Here we use a mean-field linearized theory of the sleeping cortex to derive statistics for synaptic learning and memory erasure. The growth in correlated low-frequency high-amplitude voltage fluctuations during slow-wave sleep (SWS) is characterized by a probability density function that becomes broader and shallower as the transition into rapid-eye-movement (REM) sleep is approached. At transition, the Shannon information entropy of the fluctuations is maximized. If we assume Hebbian-learning rules apply to the cortex, then its correlated response to white-noise stimulation during SWS provides a natural mechanism for a synaptic weight change that will tend to shut down reverberant neural activity. In contrast, during REM sleep the weights will evolve in a direction that encourages excitatory activity. These entropy and weight-change predictions lead us to identify the final portion of deep SWS that occurs immediately prior to transition into REM sleep as a time of enhanced erasure of labile memory. We draw a link between the sleeping cortex and Landauer's dissipation theorem for irreversible computing [R. Landauer, IBM J. Res. Devel. 5, 183 (1961)], arguing that because information erasure is an irreversible computation, there is an inherent entropy cost as the cortex transits from SWS into REM sleep.

Action Potentials↗

PubMed2006

Effects of levodopa and subthalamic nucleus stimulation on cognitive and affective functioning in Parkinson's disease.

In Parkinson's disease (PD), levodopa and subthalamic nucleus (STN) stimulation lead to major improvement in motor symptoms. Effects of both treatments on cognition and affective status are less well understood. Motor, cognitive, and affective symptoms may relate to the dysfunctioning of parallel cortico-striatal loops. The aim of this study was to assess cognition, behavior, and mood, with and without both treatments in the same group of PD patients. A group of 22 nondemented PD patients was included in this study. Patients were tested twice before surgery (off and on levodopa) and twice 3 months after surgery (OFF and ON STN stimulation, off levodopa). Cognitive and affective effects of STN stimulation and levodopa had some common, but also different, effects. STN stimulation improved performance on the planning test, associated with the dorsolateral prefrontal cortex. However, the treatments had opposite effects on tests associated with the orbitofrontal cortex; specifically, levodopa impaired while STN stimulation improved performance on the extinction phase of a reversal/extinction task. Acutely, both treatments improved motivation and decreased fatigue and anxiety. On chronic treatment (3 months after surgery), depression improved, whereas apathy worsened 3 months after surgery. To conclude, there were significant but contrasting effects of levodopa and STN stimulation on cognition and affective functions.

Affect↗

PubMed2005

Acquired dyslexia in a Turkish-English speaker.

The Turkish script is characterised by completely transparent bidirectional mappings between orthography and phonology. To date, there has been no reported evidence of acquired dyslexia in Turkish speakers leading to the naïve view that reading and writing problems in Turkish are probably rare. We examined the extent to which phonological impairment and orthographic transparency influence reading disorders in a native Turkish speaker. BRB is a bilingual Turkish-English speaker with deep dysphasia accompanied by acquired dyslexia in both languages. The main findings are an effect of imageability on reading in Turkish coincident with surface dyslexia in English and preserved nonword reading. BRB's acquired dyslexia suggests that damage to phonological representations might have a consequence for learning to read in Turkish. We argue that BRB's acquired dyslexia has a common locus in chronic underactivation of phonological representations in Turkish and English. Despite a common locus, reading problems manifest themselves differently according to properties of the script and the type of task.

Aged↗

PubMed1999

[Erbium laser phacoemulsification--a clinical pilot study].

INTRODUCTION: From August 1997 to March 1998, we performed a prospective pilot study to examine erbium laser phacoemulsification in cataract surgery under clinical conditions and to determine the side effects of this method. PATIENTS AND METHOD: 34 patients (40 eyes) with senile cataract were recruited. Slit lamp findings, keratometry, best corrected visual acuity, refraction, pachymetry, endothelial cell count and intraocular pressure were determined preoperatively and on 1st, 4th, 14th and 60th postop day according to a standardised protocol (single pulse energy between 10 and 20 mJ, frequency of application 60 Hz, average phaco time 3 min, total energy 38.5 mJ). The operations were done with the erbium laser system MCL 29, Aesculap-Meditec Co., Jena, Germany. RESULTS: A total emulsification of the nucleus was possible in 36 of 40 eyes (90%) (nucleus hardness between 0 and 3). A partial emulsification of the nucleus in nucleus hardness 3 was possible in 2 eyes, in nucleus hardness 4 in 1 eye and in nucleus hardness 2 in 1 eye (4 eyes--10%). Visual acuity increased from 0.3 preop to 0.8 two months postop (median). Intraocular pressure decreased from 16 mm Hg preoperatively to 13 mm Hg two months postoperatively (median). The increase of corneal thickness was not statistically significant compared to baseline. The decrease of endothelial cell count was 0.96%. Postoperative complications which are not known in ultrasonic phacoemulsification did not appear in erbium laser phacoemulsification. CONCLUSION: Erbium laser phacoemulsification is a surgical method that makes the emulsification of softer nuclei under clinical conditions possible with a low rate of complications also in the beginning of the learning curve. For higher nucleus hardnesses, technical and surgical parameters have to be optimised. Advantages of erbium laser phacoemulsification compared to ultrasonic phacoemulsification are less energy transmission into the eye, no heating of anterior chamber, impossibility of corneal burns and easier access in eyes that are deep into the orbit. Especially advantageous is the high protection of endothelium by erbium laser phacoemulsification. A prospective controlled comparative study to ultrasonic emulsification is desirable.

Aged↗

PubMed2005

Medical treatments and cares for geriatric syndrome: new strategies learned from frail elderly.

In Japan, there are 21 million older people above 65 years, and about 8% of them are frail elderly. Geriatrics is to study the frail elderly as to why they become frail elderly, and to treat patients properly or the remaining 92% older people not to become frail elderly. In order to promote health of the older people, geriatricians have to take deep insights for cares as well as medical treatments. With such a will, we find the way to prevent diseases in the older people. In this review, we describe medical treatments and cares for promoting successful aging.

Aged↗

PubMed2006

A hybrid neural learning algorithm using evolutionary learning and derivative free local search method.

In this paper we investigate a hybrid model based on the Discrete Gradient method and an evolutionary strategy for determining the weights in a feed forward artificial neural network. Also we discuss different variants for hybrid models using the Discrete Gradient method and an evolutionary strategy for determining the weights in a feed forward artificial neural network. The Discrete Gradient method has the advantage of being able to jump over many local minima and find very deep local minima. However, earlier research has shown that a good starting point for the discrete gradient method can improve the quality of the solution point. Evolutionary algorithms are best suited for global optimisation problems. Nevertheless they are cursed with longer training times and often unsuitable for real world application. For optimisation problems such as weight optimisation for ANNs in real world applications the dimensions are large and time complexity is critical. Hence the idea of a hybrid model can be a suitable option. In this paper we propose different fusion strategies for hybrid models combining the evolutionary strategy with the discrete gradient method to obtain an optimal solution much quicker. Three different fusion strategies are discussed: a linear hybrid model, an iterative hybrid model and a restricted local search hybrid model. Comparative results on a range of standard datasets are provided for different fusion hybrid models.

Algorithms↗

PubMed2000

Reproductive biotechnology and "big" biological questions.

In recent decades, scientists have learned to manipulate that cardinal characteristic of life, reproduction, with powerful techniques like artificial insemination, contraception, embryo transfer, cryopreservation, and cloning by nuclear transfer. While these technologies often are used for practical applications and basic research, they have another profound intrinsic quality, which is to engender deep-seated thinking about important biological questions. Examples that stimulate such thinking include a goat's giving birth to her identical twin sister via splitting embryos, cryopreservation, and embryo transfer; that a parthenogenetic embryo can never become an animal but can become a genetic mother via an aggregation chimera; or that a somatic cell can become the sole genetic parent of a calf via cloning. In this paper, I illustrate this thought-stimulating quality by considering contributions of reproductive technologies to understanding, if not completely answering, several important biological questions.

Aging↗

PubMed1999

Endogenous mechanisms of sensory modulation.

We provide evidence supporting the idea that the relationship between tissue damage, or the threat of tissue damage, and the response to such stimuli is variant and dependent on neuronal networks by which attentional, emotional and cognitive components of pain experience activate endogenous descending modulatory systems. Most previous studies have focused on responses to transient noxious stimuli with little information on the influence of descending modulation on behavioral responses to persistent pain and hyperalgesia after tissue or nerve injury. Utilizing correlative behavioral and neuronal studies we have demonstrated that (1) behavioral context modulates neuronal activity in nociceptive and non-nociceptive somatosensory pathways, supporting the hypothesis that responses in these pathways are not immutable; (2) descending modulation influences behavior and neuronal activity at spinal cord levels after inflammation and persistent pain; and (3) there are descending facilitatory as well as inhibitory influences on behavior and spinal cord neuronal activity that may impact on persistent pain particularly of deep muscle and visceral origin. Cortical as well as subcortical pathways are available by which dorsal horn activity can be modulated by attentional, motivational and cognitive factors. It appears that the same neuronal mechanisms in the forebrain and brain stem are available for behavioral modulation in a learned task involving the threat of tissue damage (transient noxious stimuli) as are available in the development and amplification of persistent pain produced by inflammation. These parallel brain mechanisms emphasize the saliency of pain experience as an important learned behavior for the survival of the organism, similar to sequential goal-directed behaviors in an operant task.

Animals↗

PubMed1996

Total Laparoscopic Hysterectomy

We analyzed our experience with laparoscopic hysterectomy and determined the most important factors that made it safe and reproducible. From January 1, 1994, to March 30, 1996, 68 laparoscopic hysterectomies were performed. The most frequent indication was uterine myomas. Average operating time decreased over the years from 6 hours in 1994 to 1.5 hours in 1996. The most important reasons for the long surgery time were surgeons' skills, uterine size, posterior wall leiomyomata, presence of adhesions, history of cesarean section, presence of deep infiltrating endometriosis with obliteration of the cul-de-sac, and equipment failure. We had no major intraoperative complications, except for a bladder injury in a woman who had had two cesarean sections, which was diagnosed and immediately repaired laparoscopically. Continuous training in endoscopic surgery, especially learning how to dissect the pelvic organs, the development of a trained team, adequate equipment, and appropriate patient selection were among the most important factors that allowed us to reach a safe level in performing this procedure.

Journal Article↗

PubMed2002

Dens invaginatus type III: report of a case and 10-year radiographic follow-up.

AIM: The purpose of this article is to report the 10-year follow-up of a right mandibular central incisor with 'dens invaginatus' that was root filled. SUMMARY: 'Dens invaginatus' is a rare malformation of teeth, probably resulting from an infolding of the dental papilla during tooth development. It has alternatively been called 'dens in dente' and 'dilated composite odontome'. Radiographic examination may clearly demonstrate this feature, although no signs may be recognized clinically. If no entrance to the invagination can be detected and there are no signs of pulp pathosis, then no treatment is required other than fissure sealing of the invagination. In deep invaginations, it is likely that root-canal treatment may be required. Occasionally, when the tooth has an immature root, apexification is necessary. Root-canal treatment of a right mandibular central incisor with 'dens invaginatus' is described along with 10-year follow-up. KEY LEARNING POINTS: Both clinical and radiographic examinations are necessary to determine morphological features of teeth before root-canal treatment. Sensibility testing to determine the pulp condition is critical prior to treatment.

Child↗

PubMedDate not supplied

[Does homosexuality have a place in psychopathology? III. Behavioral approach and homosexuality].

The behavioral approach does not propose any global explaining theory of homosexuality. It was the subject of many clinical and experimental works. Some questions and hypotheses are raised on the theoretical and therapeutical as well as ethical frames. When the behaviorist speaks of homosexuality, he only refers to the mode of behavior, at the object and not to deep characteristics of the individual. The homosexual behavior is defined as resulting from a sexual excitation in the presence of uncommon stimuli. The sexual preference is not considered as the proof of a psychopathological problem. On the etiological ground, the homosexual behavior is resulting from a social learning with a possibility of biological predisposition. The therapeutic approach is controversial. Some authors feel the behaviorist should refuse to help the patient changing his sexual orientation, even if he asks for it.

Behavior Therapy↗

PubMed2001

Problem-based learning in medical education: the Singapore hybrid.

INTRODUCTION: Problem-based learning (PBL) is an innovative educational strategy to enhance student-centred, interactive and integrated learning through intensive small group tutorials. PBL is problem-first learning in which a commonly encountered medical problem serves as the primary focus of and stimulus for learning. Several adaptations have evolved since its implementation at McMaster University in 1969. In 1999, the Singapore medical school implemented PBL as a key feature within its new hybrid curriculum. METHODS: The review will focus on the educational implications and impact of the present curriculum reform with emphasis on the implementation of PBL within the new hybrid medical curriculum. RESULTS: Our early experience in implementing PBL resembles those of several other "traditional" medical schools, namely, a generally favourable and positive response from staff and students mixed with varying degree of anxiety to change. CONCLUSION: Appropriate training and changing the mindsets of staff and students, strong leadership from the Dean and a deep commitment by all concerned are essential to ensure the successful implementation of PBL within a "traditional" medical school. PBL will enhance the quality of medical education and the educational preparation of our students to meet the challenges of future medical practice.

Education, Medical↗

PubMed1999

Back to basics.

The present study sought to establish findings and share views concerning the teaching of gross anatomy. The conclusions were drawn from feedback taken in 1995 from Year 1 (M1) through Year 5 (M5) (final year) medical students at the National University of Singapore. The survey was taken from two groups of students that had gone through two different curricula. The first group of M4 and M5 students studied under an old curriculum that taught anatomy over a period of three semesters. The second group of M1 through M3 students studied under a new curriculum of two semesters' duration. Altogether, 546 (M1: 147; M2: 120; M3: 78; M4: 107; M5: 97) completed questionnaires were analyzed. Throughout the years of study, the majority of students found dissection helpful (55.2-72. 7%) or very helpful (18.9-40.7%) in their understanding of gross anatomy. A minority of students (0-25.3%) found it not helpful. Taking all of the five years of students together, this would mean that 60.7% of the students found dissection helpful and 28% of them found it very helpful in their understanding of gross anatomy. Of the M3 students who had both dissection and demonstrations on prosected specimens, the majority of them found dissection helpful (55.2%) or very helpful (33.3%); they also found demonstrations on prosected specimens helpful (64.6%), or very helpful (27.8%). When asked whether dissection should be replaced completely by demonstrations on prosected specimens, 86.7% gave a resounding no. With regard to gross anatomy coverage, 11.7% of M4 and M5 students found it inadequate, 67.5% adequate, and 20.8% excessive. Only 1% of these students found that the gross anatomy they had learned was of no clinical relevance; 22.3% found it of little clinical relevance; and an overwhelming majority (76.7%) found it mostly clinically relevant. Most were grateful that they had been taught the basics of gross anatomy. These findings are discussed with an emphasis on the time needed and deep level approach required to gain conceptual understanding of anatomical organization.

Anatomy↗

PubMed2003

Acute psychotropic effects of bilateral subthalamic nucleus stimulation and levodopa in Parkinson's disease.

High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves the motor symptoms of Parkinson's disease (PD). Opposite changes in mood, such as mania or depression, have been reported after surgery, but it is not known whether these side effects are specifically related to STN DBS. To learn whether STN DBS also influences the limbic loop, we investigated acute subjective psychotropic effects related to levodopa or bilateral STN DBS. After a median postoperative follow-up of 12 months, 50 PD patients completed the Addiction Research Center Inventory (ARCI), assessing subjective psychotropic effects in four conditions: off-drug/on-stimulation; off-drug/off-stimulation; on-drug/off-stimulation; and on-drug/on-stimulation. Both levodopa and STN DBS improved all the ARCI subscales, indicating subjective feelings of well being, euphoria, increase in motivation, and decrease in fatigue, anxiety, and tension. A suprathreshold dose of levodopa was significantly more effective than STN DBS, using the same electrical parameters as for chronic stimulation, on four of the five ARCI subscales. We concluded that 1) both STN DBS and levodopa have synergistic acute beneficial psychotropic effects in PD, 2) the psychotropic effects of both treatments need to be considered in the long-term management of chronic STN DBS, and 3) the results indicate an involvement of the limbic STN in mood disorders of PD.

Activities of Daily Living↗

PubMed1991

The scientific bases of cancer management: at the interface between fundamental research and clinical practice.

From 1950 to 1985 the 5-year survival rate of cancer patients in industrialized countries, has slowly increased from 25% in 1950 to 50% in 1985. This progress has been due to earlier diagnosis and to a gradual improvement of treatment modalities. Clinical needs have stimulated basic research and clinical investigation. In turn, biological research has introduced new concepts and new agents. Clinical investigation and applied research have brought about an improvement in therapeutic methods and a better understanding of the growth and progression of human cancers which has, in particular, led to the concept of adjuvant treatment of occult metastases. The major recent breakthroughs in fundamental research have reinforced the value of close cooperation between clinicians and fundamentalists. Most of the new biologic tools are specific and only active on tumors cells with well-defined characteristics. Furthermore some new techniques such as adoptive immunotherapy can induce complete tumor regression in some patients and have no detectable effects in other patients with apparently similar tumors. Some cytokines have different effects on experimental and human tumors. The cytokine network is so complex that the administration of one of them can induce unpredictable effects. It has been recognized that experimental tumors and in vitro studies can be misleading and there is no substitute for clinical studies on patients. Moreover clinical experience has documented the amazing ability of tumors to become resistant to all these new agents. Numerous new therapeutic methods are being explored, however with the current state of knowledge it appears that although they can help to control tumors, they still fail to eradicate them. We must therefore learn how to integrate them with conventional therapies. Advances in therapy shall be achieved only by well-designed clinical trials. Thus at the interface between fundamental research and clinical practice there is an urgent need for oncologists with a strong scientific background and laboratory scientists with a deep interest in clinical investigations.

Clinical Trials as Topic↗

PubMed1994

A new, non-pharmacologic model of convulsive status epilepticus induced by electrical stimulation: behavioral/electroencephalographic observations and response to phenytoin and phenobarbital.

Much remains to be learned about mechanisms underlying entry into, and temporal progression of, status epilepticus (SE). This report describes a non-pharmacologic model of generalized convulsive SE in rat. Pulsed trains of suprathreshold electric current, were administered bilaterally to either of four rostral forebrain sites: orbital cortex, medial precentral cortex, deep prepiriform cortex, or rostral caudate-putamen (n = 8 per site). This induction method resulted in 30/32 animals attaining limb-clonic convulsive SE within a mean of 30-35 min for each forebrain site, with no differences between sites. Subsequent SE proceeded without further interventions, permitting observation of the natural course of progression. A stereotyped behavioral/electrographic sequence occurred, characterized by devolution. Behaviorally, animals progressed from predominantly limb clonus to head clonus, then to subtle twitching, and finally to electrical SE before cessation of spikes. The corresponding electrographic progression was from fast and slow spiking to periodic epileptiform discharges (PEDs). In 20 animals surviving to 48 h, pathologic damage affected mainly limbic sites; damage was related to total convulsive time rather than to clonic activity. High-dose phenobarbital but not phenytoin suppressed SE when given during orbital cortex-induced limb-clonic SE. These findings are compatible with human observations and indicate that this model will enable investigations of generalized SE mechanisms and evaluation of new therapeutic agents for refractory SE.

Animals↗