Showing papers by "Johns Hopkins University published in 1980"
TL;DR: The development of a clinically applicable, automatic, implantable defibrillator is described previously and this electronic device is designed to monitor cardiac electrical activity, to recognise sudden death in patients withSTEMD.
Abstract: THE development of a clinically applicable, automatic, implantable defibrillator has been described previously.1 This electronic device is designed to monitor cardiac electrical activity, to recogn...
1,262 citations
TL;DR: The data contradict the hypothesis that differential course-taking accounts for observed sex differences in mathematical ability, but support the hypotheses that these differences are somewhat increased by environmental influences.
Abstract: A substantial sex difference in mathematical reasoning ability (score on the mathematics test of the Scholastic Aptitude Test) in favor of boys was found in a study of 9927 intellectually gifted junior high school students. Our data contradict the hypothesis that differential course-taking accounts for observed sex differences in mathematical ability, but support the hypothesis that these differences are somewhat increased by environmental influences.
916 citations
TL;DR: It is proposed that vitamin D is a protective factor against colon cancer, supported by a comparison of colon cancer mortality rates in areas that vary in mean daily solar radiation penetrating the atmosphere.
Abstract: It is proposed that vitamin D is a protective factor against colon cancer. This hypothesis arose from the inspection of the geographic distribution of colon cancer deaths in the US, which revealed that colon cancer mortality rates were highest inplaces wherepopulations were exposedto theleast amountsof natural light—major cities, and rural areas at high latitudes. The hypothesis is supported by a comparison of colon cancer mortality rates in areas that vary in mean daily solar radiation penetrating the atmosphere. A mechanism involving cholecalciferol (vitamin D3) is suggested. The possibility that an ecological fallacy or another indirect association explains the findings is explored. The amount of sunlight reaching the earth’s surface varies greatly from area to area in the US. Solar radiation (including ultraviolet and visible light) reaching the ground is measured by the US Weather Bureau at a number of weather stations which are distributed throughout the country. 1 The mean daily solar
830 citations
TL;DR: The protective effects of BHA appear to be due, at least in part, to the ability of this antioxidant to increase the activities in rodent tissues of several enzymes involved in the nonoxidative metabolism of a wide variety of xenobiotics.
Abstract: 2(3)-tert-Butyl-4-hydroxyanisole (BHA) is one of several widely used antioxidant food additives that protect against chemical carcinogenesis and toxicity. The present report concerns the enhancement of dicoumarol-inhibited NAD(P)H:quinone reductase [NAD(P)H dehydrogenase (quinone); NAD(P)H:(quinone acceptor) oxidoreductase, EC 1.6.99.2] activity in mouse tissues in response to dietary administration of BHA. Cytosolic quinone reductase specific activity was increased significantly in 10 of 15 tissues examined from BHA-fed mice. The greatest proportionate increase, to 10 times control levels, was observed in liver. BHA also increased the quinone reductase activities of kidney, lung, and the mucosa of the upper small intestine severalfold. The increases of quinone reductase activities in liver and digestive tissues in response to BHA were comparable to the increases previously observed in glutathione S-transferase (EC 2.5.1.18) and epoxide hydratase (EC 3.3.2.3) activities. Quinones are among the toxic products of oxidative metabolism of aromatic hydrocarbons. NAD(P)H:quinone reductase exhibits broad specificity for structurally diverse hydrophobic quinones and may facilitate the microsomal metabolism of quinones to readily excreted conjugates. The protective effects of BHA appear to be due, at least in part, to the ability of this antioxidant to increase the activities in rodent tissues of several enzymes involved in the nonoxidative metabolism of a wide variety of xenobiotics.
757 citations
TL;DR: University students were asked to draw the path a moving object would follow in several different situations, and evidenced striking misconceptions about the motion of objects.
Abstract: University students were asked to draw the path a moving object would follow in several different situations. Over half of the students, including many who had taken physics courses, evidenced striking misconceptions about the motion of objects. In particular, many students believed that even in the absence of external forces, objects would move in curved paths.
554 citations
TL;DR: The results, taken together with the observation that cycloheximide has no effect on ligand uptake, suggest that receptors must be spared from degradation and that reutilization of receptors probably occurs.
543 citations
TL;DR: Both pancreas and brain receptors show greater sensitivity to sulfated than to desulfated COOH-terminal octapeptide of CCK and display dissociation constants of 0.3-9.5 nM, which indicate that brain and pancreAs possess distinct CCK receptors, the two tissues show some similarities.
Abstract: 125I-Labeled (Bolton-Hunter) cholecystokinin triacontatriapeptide (CCK-33) binds saturably and reversibly to distinct receptors in brain and pancreatic membranes. The peptide specificity of pancreatic CCK binding is the same as that for pancreatic amylase release. In brain, gastrin and pentagastrin display nanomolar affinity for binding sites, whereas in pancreas these two peptides are virtually inactive. Though these differences indicate that brain and pancreas possess distinct CCK receptors, the two tissues show some similarities. Both pancreas and brain receptors show greater sensitivity to sulfated than to desulfated COOH-terminal octapeptide of CCK and display dissociation constants of 0.3-9.5 nM. The pancreas possesses about 300 times more binding sites than does brain. CCK binding in both brain and pancreas is enhanced by divalent cations and reduced by monovalent cations. Receptor binding in both tissues is regulated in a selective fashion by guanyl nucleotides.
536 citations
TL;DR: Potencies of nucleosides and xanthines in competing for [3H]CHA sites indicate that specific binding is entirely to A1 adenosine receptors.
Abstract: N6-Cyclohexyl[3H]adenosine ([3H]CHA) and 1,3-diethyl-8-[3H]phenylxanthine ([3H]DPX) to bind to adenosine receptors in brain membranes. The agonist [3H]CHA has high affinity in both bovine and guinea pig brain (Kd, 0.7 nM and 6 nM, respectively). [3H]CHA binding kinetics are slow (dissociation t1/2;60 min); binding is much higher at 25 degrees C than at 0 degrees C and is inhibited by guanine nucleotides. Potencies of nucleosides and xanthines in competing for [3H]CHA sites indicate that specific binding is entirely to A1 adenosine receptors. In bovine brain, the antagonist [3H]DPX exhibits high-affinity binding (Kd, 5 nM) to the same A1 receptors that bind [3H]CHA. Binding kinetics are rapid (dissociation t1/2, 1 min), and binding is moderately higher at 0 degrees C than at 25 degrees C. In guinea pig brain, [3H]DPX binding has only moderate affintiy (Kd 50 nM), and about 60% of specific binding is to sites that resemble A2 adenosine receptors.
526 citations
TL;DR: The authors examined the potencies of 22 neuroleptic drugs competing for binding sites associated with dopamine, serotonin, alpha-adrenergic, and histamine receptors in brain membranes and found that although many neuroleptics are quite potent in competing at several receptor sites, the average antipsychotic clinical potency correlates closely only with the drug affinity for dopamine receptors labeled by 3H-spiroperidol.
Abstract: The authors examined the potencies of 22 neuroleptic drugs competing for binding sites associated with dopamine, serotonin, alpha-adrenergic, and histamine receptors in brain membranes. They found that although many neuroleptics are quite potent in competing at several of these receptor sites, the average antipsychotic clinical potency correlates closely only with the drug affinity for dopamine receptors labeled by 3H-spiroperidol At clinically effective doses, however, substantial occupancy of serotonin, alpha-adrenergic, and histamine receptors often occurs and may account for some of the auxiliary actions of neuroleptics.
517 citations
TL;DR: There may be major perinatal benefits of constant human support during labor, and mothers who had a doula present during labor were awake more after delivery and smiled at, stroked, and talked to their babies more than the control mothers.
Abstract: We studied the effects of a supportive lay woman ("doula") on the length of labor and on mother-infant interaction after delivery in healthy Guatemalan primigravid women. Initial assignment of mothers to the experimental (doula) or control group was random, but controls showed a higher rate (P less than 0.001) of subsequent perinatal problems (e.g. cesarean section and meconium staining). It was necessary to admit 103 mothers to the control group and 33 to the experimental group to obtain 20 in each group with uncomplicated deliveries. In the final sample, the length of time from admission to delivery was shorter in the experimental group (8.8 vs. 19.3 hours, P less than 0.001). Mothers who had a doula present during labor were awake more after delivery (P less than 0.02) and stroked (P less than 0.001), smiled at (P less than 0.009), and talked to (P less than 0.002) their babies more than the control mothers. These observations suggest that there may be major perinatal benefits of constant human support during labor.
438 citations
TL;DR: It is proposed that mu and delta receptors are respectively the physiologic receptors for [Met]- and [Leu]enkephalin neurons.
Abstract: We have observed two discrete populations of opiate receptors that are differently localized in rat brain. Morphine-like (mu) receptors, labeled by 125I-labeled [D-Ala-2MePhe4Met(O)5-ol]enkephalin, are concentrated selectively in lamina IV of the cerebral cortex, certain thalamic nuclei, and the periaqueductal grey, while delta receptors, labeled by 125I-labeled [D-Ala2-D-Leu5]enkephalin, are more diffused, having high densities in cerebral cortex, corpus striatum, amygdala, and olfactory tubercle. Because of similarities in their localizations, we propose that mu and delta receptors are respectively the physiologic receptors for [Met]- and [Leu]enkephalin neurons. These distributions reflect the different physiological functions attributed to mu and delta receptors and thus represent discrete functions of [Met]- and [Leu]enkephalin neurons.
TL;DR: There was no correlation between amount of psychopathology and either colonic motility or severity of symptoms in the whole group of IBS patients, and patients with IBS showed significantly elevated levels on the following psychological traits.
Abstract: Patients with different irritable bowel symptoms and normal subjects were compared to determine whether subtypes of irritable bowel syndrome (IBS) could be distinguished on the basis of colonic motility or psychological test scores. A provocative test involving stepwise distension of the rectosigmoid area revealed two types of colonic motility. Slow contractions having durations of at least 15 sec and occurring at irregular intervals were more frequent in IBS patients than in normals but did not differentiate constipation from diarrhea. Fast contractions having durations of less than 15 sec and occurring in runs at frequencies of 6-9 cpm were more frequent in patients with diarrhea than in normals or constipated IBS patients. Constipated patients showed no more fast contractions than normals. Severity of bowel symptoms was correlated with the overall amount of motility (motility index) in patients with diarrhea but not in patients with constipation. Patients with IBS showed significantly elevated levels on the following psychological traits: anxiety, interpersonal sensitivity, depression, hostility, and somatization of affect. However, there were no significant trait differences between patients with diarrhea and those with constipation. Also, there was no correlationbetween amount of psychopathology and either colonic motility or severity of symptoms in the whole group of IBS patients.
TL;DR: It appears that pressure generation and blood flow during CPR in the dog result from a generalized rise in intrathoracic pressure, not from direct cardiac compression, which can dramatically increase carotid blood flow During CPR.
Abstract: SUMMARYDespite the widespread clinical appliciktion of cardiopulmonary resuscitation (CPR), the mechanism responsible for blood flow during this maneuver remains undefined, although it has been assumed that blood is squeezed from the heart by direct compression of the sternum. We studied the hemodynamics of CPR in 15 arrested dogs. During chest compression, pressures in the left ventricle, aorta, right atrium and pulmonary artery were essentially identical. These pressures were also equal to the intrathoracic. pressure as estimated by an esophageal balloon catheter. Unequal transmission of pressures to the extrathoracic arterial and venous system resulted from collapse of the great veins at the thoracic outlet as intrathoracic pressures rose. This phenomenon gave rise to a peripheral arteriovenous pressure gradient and antegrade flow. When intrathoracic pressure was increased by maintaining the lungs fully inflated during chest compression, aortic systolic pressure rose from 27.3 ± 4.0 mm Hg to 58.4 7.9 mm Hg (p < 0.001) and carotid blood flow increased from 9.0 ± 2.2 ml/min to 28.6 ± 5.9 ml/min (p < 0.001). Increasing the intrathoracic pressure by tightly binding the abdomen to prevent paradoxical diaphragmatic motion during chest compression also resulted in a rise in aortic systolic pressure, from 29.4 ± 3.2 to 57.7 ± 7.7 mm Hg (p < 0.001), and an increase in carotid blood flow, from 14.5 ± 8.1 ml/min to 32.3 9.7 ml/min (p < 0.005). It appears that pressure generation and blood flow during CPR in the dog result from a generalized rise in intrathoracic pressure, not from direct cardiac compression. Maneuvers that raise the intrathoracic pressure can dramatically increase carotid blood flow during CPR.
TL;DR: It is concluded that tobramycin causes nephrotoxicity less frequently than does gentamicin.
Abstract: Two hundred fifty-eight patients with suspected sepsis were treated with tobramycin or gentamicin in a prospective, randomized, double-blind trial. One hundred forty-six patients received nine or more doses, had serial determinations of serum creatinine, and were evaluated for nephrotoxicity; 91 were able to cooperate with audiometry and were evaluated for auditory toxicity. Auditory toxicity developed in five of 47 (10 per cent) given gentamicin and five of 44 (11 per cent) given tobramycin. Nephrotoxicity developed in 19 of 72 (26 per cent) given gentamicin and nine of 74 (12 per cent) given tobramycin (P less than 0.025). The severity of the nephrotoxicity was not different; the mean increase in creatinine was 1.3 mg per 100 ml (114.9 mumol per liter) in both groups. Both the tobramycin and gentamicin groups had a similar mean age, initial serum creatinine level, total dose, serum aminoglycoside level, and duration of therapy. We conclude that tobramycin causes nephrotoxicity less frequently than does gentamicin.
TL;DR: The prevalence of mental disorders, hypertensive disease, cerebrovascular disease and other chronic conditions are increasing throughout the world and will continue to increase in the absence of effective techniques for reducing incidence.
Abstract: Prevalence rates of mental disorders, hypertensive disease, cerebrovascular disease and other chronic conditions are increasing throughout the world. Two mechanisms are responsible for this situation: the large relative increases that are occurring in the number of persons in age groups at high risk for developing these conditions; and the increase in average duration of chronic diseases resulting from the successful application of techniques for arresting their fatal complications and prolonging the lives of affected individuals. In the absence of effective techniques for reducing incidence, the prevalence of such diseases will continue to increase.
The chronic mental disorders and conditions related to them are used to illustrate the manner in which these mechanisms are operating. Data are presented to demonstrate the increases likely to occur between 1975 and 2000 in the number of persons with these conditions in the more and less developed regions of the world and in selected countries.
These findings set new priorities for future epidemiologic research. Emphasis must be placed on discovering the preventable causes of the conditions which are increasing in prevalence.
TL;DR: The NFL examination is as sensitive in detecting eyes with field loss as the optic disc configuration and may help to identify which eyes are suffering optic nerve damage prior to field loss.
Abstract: To evaluate the usefulness of the retinal nerve fiber layer (NFL) appearance in the estimation of glaucomatous optic nerve damage, we examined 335 eyes of normal, glaucoma suspect, of glaucomatous patients. In eyes with field loss, 84% had NFL atrophy. In normal eyes, NFL atrophy was suspected in 3%. In glaucoma suspects, 13% of eyes had NFL defects. Defects in glaucoma suspect eyes were more often localized, compared with the diffuse atrophy found in eyes with visual field loss. The NFL abnormalities were seen in areas of the retina corresponding to the location of visual field defects with a high accuracy. The NFL examination is as sensitive in detecting eyes with field loss as the optic disc configuration and may help to identify which eyes are suffering optic nerve damage prior to field loss.
Journal Article•
TL;DR: Axons of the superior and inferior optic nerve head and nerve seem to be damaged more extensively than those in the nasal and temporal optic nerve, and Astrocytes and capillaries of the optic nerveHead seem to tolerate elevated IOP well and were relatively spared.
Abstract: Intraocular pressure (IOP) elevations lasting from 2 to 42 days were produced in 13 primate eyes by anterior chamber injections of autologous, fixed red blood cells. The retina, optic nerve head, and optic nerves were studied by electron microscopy, and ganglion cell rapid axonal transport was examined after IOP elevations for various durations. Transport of axonal material was blocked at the scleral lamina cribrosa by IOP elevations to 50 mm Hg. With IOP elevation for less than 1 week, return to normal IOP restored normal transport in some axons. However, in other axons IOP elevation for less than 1 week intiated ganglion cell degeneration. The process of cellular death involved a rapid ascending degeneration from nerve head to brain, followed 3 to 4 weeks later by descending degeneration of the ganglion cell body and its attached axon. Axons of the superior and inferior optic nerve head and nerve seem to be damaged more extensively than those in the nasal and temporal optic nerve. Two to four days after IOP elevation, axons of the superficial optic nerve head were swollen with accumulating axonal material, leading to histologic disk edema. In those eyes with IOP elevation longer than 1 week, the loss of anterior disk nerve fibers combined with posterior and lateral movement of the lamina cribrosa lead to an increase in optic disk cupping. Astrocytes and capillaries of the optic nerve head seem to tolerate elevated IOP well and were relatively spared.
TL;DR: A prospective collaborative study was conducted in five centers during a 13-year period to identify factors that influence the development of visual-field defects (GVFDs) of open angle glaucoma, and found their collective predictive power to be undesirably poor.
Abstract: • A prospective collaborative study was conducted in five centers during a 13-year period to identify factors that influence the development of visual-field defects (GVFDs) of open angle glaucoma. In 5,000 subjects, GVFDs developed in only 1.7% of eyes. Statistical analysis of 26 factors at first examination identified five that were significantly related to the development of GVFDs—outflow facility, age, applanation pressure, cup-disc ratio, and pressure change after water drinking. Their absolute initial value, and not its change with time, was the important predictor. Multivariate analysis showed their collective predictive power to be undesirably poor, indicating that other factors must play an important role in the development of GVFDs. Mortality-table analysis indicated that during a period of five years, 98.54% of eyes with initial pressure less than 20 mm Hg continued to be free from GVFDs as compared with 93.34% of those with pressure 20 mm Hg or greater.
TL;DR: Population dynamics of corals and other colonial animals are complicated by their modular construction and growth, which distort the relationship between size and age among reef corals.
Abstract: Population dynamics of corals and other colonial animals are complicated by their modular construction and growth. Partial colony mortality, colony fission, and colony fusion distort any simple relationship between size and age among reef corals.
TL;DR: The thalamocortical and corticothalamic connections of the three cortical auditory fields—first (AI), second (AII), and anterior (AAF)—were defined using anterograde and retrograde tracing techniques to determine the systematic topographies of the connections between these cortical fields and the medial geniculate body subdivisions.
Abstract: The thalamocortical and corticothalamic connections of the three cortical auditory fields—first (AI), second (AII), and anterior (AAF)—were defined using anterograde and retrograde tracing techniques. Microinjections of tracers were placed at one or two different physiologically identified loci after these fields had been mapped using microelectrode recording techniques. This approach ensured that the injections were well within the borders of each field that was studied. By making injections at different positions in the cochleotopic representations in A1 and AAF the systematic topographies of the connections between these cortical fields and the medial geniculate body subdivisions were determined.
The thalamocortical and corticothalamic reciprocal projections of single loci in AI were from and to single columns passing rostrocaudally through the deep dorsal nucleus (Dd) and medial division (M) of the medial geniculate body (MGB) and from and to folded sheets of labelled neurons passing rostrocaudally through pars lateralis (VI) and pars ovoidea (Vo) of the ventral division. The connections of AI with VI and Vo were very strong. There were also thalamocortical and corticothalamic connections between the lateral division of the posterior group of thalamus (Pol) and single loci in AI.
The thalamocortical and corticothalamic reciprocal connections of AAF with the auditory thalamus were similar to the A1 connections with the exception that the connections with the ventral division of the MGB were relatively weaker and, in the case of the thalamocortical projection, more discontinuous.
AII loci are thalamocortically and corticothalamically connected with the caudal dorsal nucleus (Dc), the ventral lateral nucleus (VL), and the medial division (M).
The topography of all connections of AAF and A1 with the MGB varied systematically and was consistent with a cochleotopic organization of connections between the MGB and the two cortical fields.
Since the thalamocortical and corticothalamic connections of these three cortical fields are reciprocal, we were able to compare directly their connections in individual cats by introducing anterograde tracer in one field and retrograde tracer in another. While AI and AAF were connected to the same subdivisions of the MGB and had the same systematic topography of connections, the connections of AII and AI (or AAF) were largely segregated (with the only overlap occurring in M). Results of injections introduced into other cortical fields in this study and the results of previous studies by other investigators (Rose and Woolsey, '58; Graybiel, '73; Casseday et al., '76; Winer et al., '77) are consistent with the interpretation that there are two largely segregated connectional systems between the auditory thalamus and cortex: a “cochleotopic system” that includes AI and AAF and a “diffuse system” that includes AII.
Small injections of anterograde tracers at higher-frequency representational sites in AI or AAF, or of retrograde tracer in AI, produced a discontinuous, periodic pattern of dense and light labelling in VI. Reconstructions showed that these discontinuities of label, in three dimensions, formed parallel columns oriented rostrocaudally.
TL;DR: In this article, four balanced cross sections, supported by longitudinal sections, structure contour maps, stratigraphic separation diagrams and hangingwall sequence diagrams are used to estimate the Moine thrust.
Abstract: Four balanced cross sections, supported by longitudinal sections, structure contour maps, stratigraphic separation diagrams and hangingwall sequence diagrams are keys to this interpretation of the Moine thrust, which forms the western margin of the Caledonides in NW Scotland. New basement and cover correlations between foreland and thrust belt give new slip estimates for the Moine thrust (∼ 77 km), the Loch More klippe (≥ 43 km), Glencoul sheet (20–25 km), Ben More sheet (∼28 km), Achall and Dundonnell ‘sheet II’ (∼28 km).Like other major thrusts the Moine thrust moved in a smooth or rough fashion at different places and times, and many structures are a footwall response to its passage. Widely developed duplexes vary in thickness so that the roof thrust is folded and occasionally faulted; many late Caledonian folds in the Moine metasediments are of this origin. The presence of igneous bodies with contact aureoles increased the propensity to rough slip and this, by causing thickening in the footwall to the Moine thrust, is partly responsible for the Assynt culmination.The previously accepted sequence of thrusting from foreland to hinterland, which has been deduced from the concept of ‘overstep’ of the Moine thrust across lower thrusts, is considered to be a misconception of thrust geometry. Instead, a ‘piggy-back’ sequence of thrusts, from higher to lower, is proposed.
TL;DR: Standard therapy with epinephrine and fluids did not immediately reverse either the hemodynamic or the respiratory abnormalities in the two subjects with the most severe anaphylactic shock, and Hemodynamic recovery was gradual and did not seem directly related to any specific therapeutic intervention.
Abstract: In the course of a controlled study to evaluate different forms of immunotherapy for subjects with insect-sting hypersensitivity, we observed 11 subjects who had systemic cutaneous urticarial reactions and 3 subjects who experienced systemic anaphylaxis. With the exception of tachycardia, there were no cardiopulmonary changes in the subjects with urticaria, whereas the major manifestation of anaphylactic shock in the other three subjects was severe hypotension that was probably secondary to peripheral vasodilation. Significant abnormalities in gas exchange developed in two subjects. In one, bronchospasm precipitated a respiratory arrest followed by endotracheal intubation with mechanical ventilation. Although plasma histamine levels were not related to the development of cutaneous reactions, the plasma histamine levels correlated with the severity and duration of the cardiopulmonary changes observed during anaphylactic shock. The two subjects with the most severe shock showed evidence of intravascular coagulation characterized by a diminution of Factor V, Factor VIII, fibrinogen, and high molecular weight kininogen, as well as changes in components of the complement system. Standard therapy with epinephrine and fluids, usually recommended for the treatment of systemic anaphylaxis, did not immediately reverse either the hemodynamic or the respiratory abnormalities in the two subjects with the most severe anaphylactic shock. Hemodynamic recovery was gradual and did not seem directly related to any specific therapeutic intervention.
TL;DR: Only rats with functional hippocampal systems were able to perform the maze task accurately while thos rats with lesions in the hippocampal system were not.
TL;DR: Specific sex steroid hormone binding sites have been identified in a discrete nuclear subfraction that is chromatin-depleted and salt-insoluble and contains a residual pore complex-lamina, remnants of an internal network, and a residual nucleolus.
TL;DR: A critical review of the literature provides the basis for a redefinition of the syndrome that considerably broadens its classical description, and the argument is advanced that the focus of neuropsychological explanation should be on theoretically separable psychological mechanisms that might be disrupted in relative isolation from other components in conditions of focal brain damage.
Abstract: A neuropsychological theory is offered to account for the syndrome of Broca's aphasia. A critical review of the literature, with emphasis on recent research, provides the basis for a redefinition of the syndrome that considerably broadens its classical description. The argument is advanced that the focus of neuropsychological explanation should be on theoretically separable psychological mechanisms that might be disrupted in relative isolation from other components in conditions of focal brain damage, rather than on isolated units of aphasic performance. The symptoms that characterize Broca's aphasia are explained as predictable behavioral manifestations of a central disruption of the syntactic parsing component of the language System, coupled with a (theoretically independent) articulatory deficit that affects only the speech output System. The neuroanatomical implications of this argument are considered within the framework of the classical “strong localizationist” hypothesis.
TL;DR: It is proposed that strand scission at a dimer site by the M. luteus enzyme requires two activities, a pyrimidine dimer DNA-glycosylase and an apyrimidinic/apurinic endonuclease.
Abstract: Pyrimidine dimer formation in response to UV radiation is governed by the thymine content of the potential dimer and the two flanking nucleotides. An enzymatic activity can be purified from Micrococcus luteus that cleaves the N-glycosyl bond between the 5′ pyrimidine of a dimer and the corresponding sugar without rupture of a phosphodiester bond. We propose that strand scission at a dimer site by the M. luteus enzyme requires two activities, a pyrimidine dimer DNA-glycosylase and an apyrimidinic/apurinic endonuclease.
TL;DR: Computed tomography with thin sections was used to assess tissue density in 91 apparently noncalcified pulmonary nodules in 88 patients, and it is presumed that nodules with representative CT numbers of 164 H are benign, and that diffuse calcification likely accounts for the higher CT number of some benign lesions.
Abstract: The management of a patient over the age of 40 years with a solitary pulmonary nodule (SPN) detected by plain chest roentgenography has been a source of concern for more than 3 decades [1–6]. Excision of an SPN, including resection of the involved lobe, became a feasible technique in the early 1950s. As data on such cases accumulated it became apparent that a significant percentage of innocent-appearing peripheral pulmonary nodular lesions actually represented lung cancers [1]. The prevailing philosophy regarding such lesions is that tissue diagnosis (occasionally by needle biopsy but more frequently by thoracotomy) is mandatory in order to exclude the possibility of a malignant lesion. We summarized the results of the five largest reported series of thoracotomies for SPNs and noted that most resected lesions were actually benign [1–6]. In almost every case in which thoracotomy was carried out for a benign lesion, the operation would have been unnecessary if the nature of the lesion could have been determined by noninvasive methods. The need for surgery was indeed a reflection of the inadequacy of diagnosis techniques.