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J R Lee

Publications and source records attributed to J R Lee.

122 records · Page 7Linked to original sources
PubMed1971

How does the striate cortex begin the reconstruction of the visual world?

The striate cortex transforms the topographic representation of visual space in the lateral geniculate body into a Fourier transform or frequency representation at the complex cell level via the intermediary simple cell stage of "strip integration." Each of these three stages contains essentially the same amount of information, which expresses a conservation of information principle; however, the form of the information is changed. In the transform domain, invariant descriptions of visual objects can be derived to serve as the basic sets required for pattern recognition and memory. We believe that our experimental and theoretical findings are fundamental for understanding the functional organization of the striate cortex.

Animals↗
PubMedDate not supplied

Neurobiological studies of reading and reading disability.

UNLABELLED: Evidence from neuroimaging studies, including our own, suggest that skilled word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo-parietal) circuit and a ventral (occipito-temporal) circuit. This posterior system appears to be functionally disrupted in developmental dyslexia. Relative to nonimpaired readers, reading-disabled individuals demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers, the dorsal circuit predominates at first, and in conjunction with premotor systems, is associated with analytic processing necessary for learning to integrate orthographic with phonological and lexical semantic features of printed words. The ventral circuit constitutes a fast, late-developing, word form system, which underlies fluency in word recognition. LEARNING OUTCOMES: As a result of this activity, (1) the participant will learn about a model of lexical processing involving specific cortical regions. (2) The participant will learn about evidence which supports the theory that two dorsal LH systems may be disrupted in developmental dyslexia. (3) The participant will learn that individuals with reading impairment may rely on other regions of the brain to compensate for the disruption of posterior function.

Brain↗
PubMedDate not supplied

Modified smear method for screening potential inhibitors of platelet aggregation from plant sources.

The smear method developed by Velaskar and Chitre was modified to allow the massive screening of plant extracts and/or fractions for platelet antiaggregating activity. Aspirin and papaverine, known inhibitors of platelet aggregation, were tested by the modified method and showed comparable results with previously reported data. Fifty-four fractions prepared from eighteen plant species were screened for their inhibitory effects on adenosine 5'-diphosphate, arachidonic acid, or collagen-induced rat platelet aggregation. The results suggest that plants could be a potential source of inhibitors of platelet aggregation.

Adenosine Diphosphate↗
PubMedDate not supplied

Potential inhibitors of platelet aggregation from plant sources, III.

3,4-Dihydroxybenzoic acid (DBA) was isolated from Acanthopanax senticosus as an antiplatelet aggregatory substance. This paper also reports the results of the investigations on the structural activity relationships among the various dihydroxybenzoic acid derivatives against rat platelet aggregations induced by ADP (adenosine 5'-diphosphate), AA (arachidonic acid), or collagen.

Adenosine Diphosphate↗
PubMedDate not supplied

Myocardial perfusion and angiographic correlations in patients with ST-segment elevation during dobutamine stress perfusion imaging.

BACKGROUND: There is scanty information on the angiographic and myocardial perfusion correlates of dobutamine-induced ST-segment elevation. METHODS AND RESULTS: We studied 39 patients who exhibited ST-segment elevation during dobutamine perfusion tomography and had recent coronary angiography performed (ie, within 3 months of the dobutamine study). Baseline characteristics, extent of coronary artery disease, relationship of Q waves to ST-segment elevation, ischemic burden, and angiographic findings were assessed. Twenty-nine patients (74%) had prior myocardial infarction, and 77% had abnormal Q waves at baseline. Ninety-three percent of patients had abnormal perfusion imaging. Eighty percent of patients had multivessel coronary artery disease. The left ventricular ejection fraction by contrast ventriculography was 35% +/- 7% (mean +/- SD), the perfusion defect size was 32% +/- 15%, and 73% of patients had some degree of myocardial ischemia. A predominance of ischemia (>50% reversibility) occurred in 38% of patients with Q waves and in 70% of those without Q waves. There was also good agreement between the site of ST-segment elevation and the site of ischemia by perfusion imaging (79%) and between the site of ST-segment elevation and the location of the vessel with significant coronary stenosis (95%). CONCLUSIONS: Patients with dobutamine-induced ST-segment elevation have a depressed left ventricular ejection fraction, a high frequency of multivessel disease, and markedly abnormal myocardial perfusion tomography. In patients with ST-segment elevation and abnormal Q waves, substantial scarring and superimposed ischemia coexist, whereas in patients without Q waves, ST-segment elevation usually denotes severe ischemia.

Adrenergic beta-Agonists↗
PubMedDate not supplied

Effects of morphine on brain histamine, antinociception and activity in mice.

1. The effect of morphine on the histamine content of the mouse brain has been investigated. The changes in the brain histamine level have been related to morphine-induced analgesia and morphine-induced changes in locomotor activity. 2. With doses of morphine between 1 and 5 mg/kg there was a significant increase in histamine levels. The time required to produce a maximal rise in the brain histamine level with 5 mg/kg of morphine was 15 min. 3. There was a significant decrease in brain histamine levels with doses of morphine between 7-5 and 100 mg/kg. The time at which the greatest decrease was produced with 50 mg/kg was 30 min. 4. The time couse of the alteration of brain histamine by morphine did not correlate with its antinociceptive activity. Both the 5 and 50 mg/kg doses of morphine produced analgesia in mice whereas brain histamine levels were increased and decreased, respectively. 5. Pretreating mice with compounds which modify histaminergic function did not modify the antinociceptive action of morphine. 6. Morphine produced a biphasic effect on locomotor activity when the dose was increased from 0-5 through to 100 mg/kg. Doses up to 2-5 mg/kg caused a reduction of activity and doses above this produced significant increases. 7. There appears to be an inverse relationship between the morphine-induced changes of brain histamine and the morphine-induced changes in locomotor activity.

Analgesics, Opioid↗
PubMedDate not supplied

The effect of gynaecological laparoscopic surgery on cerebral oxygenation.

During gynaecological laparoscopic surgery, alterations in cerebral blood flow and intracranial pressure are frequently reported. These changes affect cerebral perfusion pressure and thus may affect cerebral oxygenation. In this prospective study, the effect of gynaecological laparoscopic surgery on cerebral oxygenation was examined by following the changes in regional cerebral oxygen saturation (rSo2). Twenty-four female patients were enrolled. The mean rSo2 was 65.5 +/- 5.4% at baseline before surgery, 60.8 +/- 5.6% when the patient was placed in the Trendelenburg position, 57.1 +/- 9.3% after creation of pneumoperitoneum, and 64.0 +/- 7.3% after the completion of surgery. During the period of pneumoperitoneum, rSo2 fell below 50% in two hypercapnic patients. In comparison with baseline, rSo2 declined significantly in the Trendelenburg position. The creation of pneumoperitoneum itself did not decrease the average rSo2 value further unless the patients were hypercapnic.

Adult↗
PubMedDate not supplied

Rab11 in dysplasia of Barrett's epithelia.

Barrett's esophagus predisposes affected patients to the development of esophageal adenocarcinoma. The development of adenocarcinoma proceeds along a progression through low- and high-grade dysplasia. Surveillance of Barrett's patients requires serial endoscopic investigations and grading mucosal biopsies. Unfortunately, grading of biopsies by conventional hematoxylin and eosin staining is fraught with significant interobserver variations. We have found in both biopsy and resection specimens that immunostaining for the small GTP binding protein Rab11 is increased in low-grade dysplastic cells. This staining is lost in high-grade dysplastic cells. These results suggest that low-grade dysplastic cells undergo an apical trafficking blockade, which is released as cells progress to the less differentiated phenotype of high-grade dysplasia and adenocarcinoma. Examination of the SKGT-4 esophageal adenocarcinoma cell line demonstrated prominent mRNA and protein expression for Rab11. Rab11 immunostaining was present in SKGT-4 cells as a perinuclear nidus of punctate staining along with a more diffuse punctate pattern. Thus, Rab11 expression was present in a esophageal adenocarcinoma cells in culture. Markers of vesicle trafficking may be critical factors for grading of mucosal dysplastic transitions leading to adenocarcinoma.

Adenocarcinoma↗
PubMedDate not supplied

Pulmonary veins in total anomalous pulmonary venous connection with obstruction: demonstration using silicone rubber casts.

We studied the postmortem vascular anatomy of four patients with total anomalous pulmonary venous connection (TAPVC) with obstruction using a silicone rubber casting method. Two patients were studied clinically but died before therapeutic intervention, one died after corrective surgery, and another was not diagnosed before death. The morphologic types were supracardiac (2), infracardiac (1), and mixed (1). One of the supracardiac forms had a stenosis at the left vertical vein by a bronchoarterial vise, and a collateral channel to the right superior caval vein was also present. In the other supracardiac case, a left upper pulmonary vein was connected to the left vertical vein above the stenotic portion, resulting in postoperative pulmonary hemorrhage into the left upper lobe. The patient with infracardiac TAPVC had a tree-shaped descending vertical vein and small opening at the inferior caval vein. In the mixed type, a right upper pulmonary vein ran between the pulmonary artery and bronchus draining into the superior caval vein, and the rest of the drainage was to the portal vein.

Autopsy↗
PubMedDate not supplied

Fluoride therapies.

Explore the source record for details and available documents.

Child↗
PubMedDate not supplied

Gastrointestinal pathology in sickle cell disease.

The literature was reviewed to investigate the existence of unique gastrointestinal (GI) pathological lesions in sickle-cell disease (SCD). Chole- and choledocholithiasis have long been recognized, but bilirubin gallstones can occur in any chronic hemolytic anemia. Acute pancreatitis has been reported as a possible ischemic consequence of sickling. It is unclear if the hepatic lesions of SCD differ from those of any chronically transfused population. Hepatic failure has been associated with massive sickling and hyperviscous bile ("sludge") has been linked to SCD. Elevated 5'-nucleotidase in the presence of elevated aminotransferase may suggest both hepatic and biliary tree involvement in a subgroup of patients with SCD. Low levels of the hepatically produced coagulation inhibitors, Protein S and Protein C, have been identified in SCD, but their precise relation to thrombosis in this instance remains unclear. Finally, a syndrome of intracanalicular cholestasis, sinusoidal dilation. Kupffer cell hyperplasia, and erythrophagocytosis has been linked to SCD. It has been suggested that the use of exchange transfusion prior to liver biopsy in this group of pediatric SCD patients may mask the pathophysiological role of sickled red blood cells in hepatic dysfunction. With the exception of some of the situations cited, it is concluded that most GI lesions in SCD are common to a heavily transfused population with chronic hemolytic anemia.

Anemia, Sickle Cell↗