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  • Articles: DFG German National Licenses  (8)
  • GK rat  (3)
  • Kitten LGN  (3)
  • Pituitary hormones  (2)
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  • Articles: DFG German National Licenses  (8)
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Years
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    A clinical and histopathological study of factors affecting MRI signal intensities of pituitary adenomas (1994)
    Springer
    Neuroradiology 36 (1994), S. 298-302 
    Details
    ISSN: 1432-1920
    Keywords: Pituitary adenoma ; MRI ; Immunohistochemistry ; Pituitary hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Our aim was to elucidate the factors which determine the MRI signal intensities of pituitary adenomas. We examined 51 patients with surgically-confirmed pituitary adenomas. Using a spin-echo pulse sequence (SE 500/15), coronal and sagittal images (3 mm slices) were obtained. Signal intensities on T1-weighted images were measured in the parenchyma of the adenoma and in normal grey matter. The relative intensity of the adenoma was assessed by calculating the ratio of its signal intensity to that of the normal grey matter of the same patient. Parafin-embedded sections were used for haematoxylin and eosin staining. The number of cells in a prescribed area was counted, and the mean of five such counts was taken as the cell density. Immunohistochemically stained sections using antibodies for various pituitary hormones were similarly examined; the ratio of the total number of hormone-positive cells to the overall total number of adenoma cells was calculated. Four independent variables were used in the analysis: the age of the patient, the maximum diameter of the adenoma, the cell density and the proportion of hormone-positive cells in the adenoma and, with the signal intensity ratio as the dependent variable, a multiple regression analysis was performed. This revealed that the the greatest influence upon the signal intensities on T1-weighted images was the proportion of hormone positive cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593265
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Properties of LGN cells in kittens reared with convergent squint: A neurophysiological demonstration of amblyopia (1976)
    Springer
    Experimental brain research 25 (1976), S. 63-77 
    Details
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Single cell ; Convergent squint ; Visual acuity ; Amblyopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial resolution of LGN cells has been studied in 4–5 month old kittens raised with convergent squint surgically produced in one eye at the age of 3–4 weeks. The ‘sustained’ cells which received inputs from the central retina of the squint eye showed significantly poorer spatial resolution (determined by the highest spatial frequency of a sinusoidal grating to which a cell responded with modulated firing) than those which received inputs from the central retina of the normal eye. The spatial resolution of cells which received inputs from the peripheral retina of the squint eye was not different from that of cells receiving inputs from the peripheral retina of the normal eye. The visual latency of ‘sustained’ cells which received an input from the area centralis of the squint eye was considerably lengthened and the response showed a sluggish onset. Thus the most important clinical symptom of amblyopia, namely the reduction of foveal visual acuity, has been demonstrated in kittens raised with unilateral vonvergent squint. The results suggest that the lesion responsible for amblyopia due to squint might be a functional degeneration of the high spatial frequency tuning cells in the pathway prior to the visual cortex, i.e. in the retina or LGN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237326
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Immunohistochemical study of Rathke's cleft cyst (1988)
    Springer
    Acta neuropathologica 77 (1988), S. 33-38 
    Details
    ISSN: 1432-0533
    Keywords: Rathke's cleft cyst ; Immunohistochemistry ; Pituitary hormones ; Intermediate filament ; Squamous metaplasia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An immunohistochemical study was made of ten cases of asymptomatic and three cases of symptomatic Rathke's cleft cyst. The cysts in the asymptomatic cases had monolayer columnar or cuboidal epithelium. Within the epithelium, cells which were positive for at least one of the pituitary hormones were found. The rate of positive reactions for these six pituitary hormones was between 70% and 100%. In contrast, the cysts in the symptomatic cases had an epithelium which was partly stratified squamous and partly squamous epithelium, and none of the pituitary hormones were found in them. Therefore, when a Rathke's cleft cyst enlarges to the extent that clinical symptoms are produced, we consider that changes have already occurred in structure and function of the cyst epithelium. In addition, we believe there is a tendency for monolayer epithelia to undergo squamous metaplasia and for cells which are positive for pituitary hormones to change into non-granulated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688240
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Hyperresponse in calcium-induced insulin release from electrically permeabilized pancreatic islets of diabetic GK rats and its defective augmentation by glucose (1995)
    Springer
    Diabetologia 38 (1995), S. 772-778 
    Details
    ISSN: 1432-0428
    Keywords: Key words Insulin release ; intracellular calcium ; exocytosis ; GK rat ; permeabilized islets.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In spontaneously diabetic GK rats, insulin secretion from pancreatic beta cells in response to glucose is selectively impaired, probably due to deficient intracellular metabolism of glucose and impaired closure of KATP channels during glucose stimulation. By using electrically permeabilized islets of GK rats, we explored the functional modulations in exocytotic steps distal to the rise in [Ca2 + ]i in the diabetic condition. At 30 nmol/l Ca2 + (basal conditions) insulin release was similar between GK and non-diabetic control Wistar rats. In response to 3.0 μmol/l Ca2 + (maximum stimulatory conditions), insulin release was significantly augmented in permeabilized GK islets (p 〈 0.01). Raising glucose concentrations from 2.8 to 16.7 mmol/l further augmented insulin release induced by 3.0 μmol/l Ca2 + from permeabilized control islets(p 〈 0.001), but had no effect on that from permeabilized GK islets. The stimulatory effect of glucose on insulin release from permeabilized control islets was partly inhibited by 2,4-dinitrophenol, an inhibitor of mitochondrial oxidative phosphorylation (p 〈 0.01). The hyperresponse to Ca2 + in GK islets may play a physiologically compensatory role on the putative functional impairment both in [Ca2 + ]i rise and energy state in response to glucose in diabetic β cells, and may explain the relative preservation of insulin release induced by non-glucose depolarizing stimuli, such as arginine, from pancreatic islets in non-insulin-dependent diabetes mellitus. [Diabetologia (1995) 38: 772–778]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050351
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Reduced sensitivity of dihydroxyacetone on ATP-sensitive K+ channels of pancreatic beta cells in GK rats (1994)
    Springer
    Diabetologia 37 (1994), S. 1082-1087 
    Details
    ISSN: 1432-0428
    Keywords: Dihydroxyacetone ; ATP-sensitive K+ channels ; GK rat ; glycerol phosphate shuttle ; pancreatic beta cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the GK (Goto-Kakizaki) rat, a genetic model of non-insulin-dependent diabetes mellitus, glucose-induced insulin secretion is selectively impaired. In addition, it has been suggested by previous studies that impaired glucose metabolism in beta cells of the GK rat results in insufficient closure of ATP-sensitive K+ channels (KATP channels) and a consequent decrease in depolarization, leading to a decreased insulin release. We have recently reported that the site of disturbed glucose metabolism is probably located in the early stages of glycolysis or in the glycerol phosphate shuttle. In the present study, in order to identify the impaired metabolic step in diabetic beta cells, we have investigated insulin secretory capacity by stimulation with dihydroxyacetone (DHA), which is known to be directly converted to DHA-phosphate and to preferentially enter the glycerol phosphate shuttle. In addition, using the patch-clamp technique, we also have studied the sensitivity of DHA on the KATP channels of beta cells in GK rats. The insulin secretion in response to 5 mmol/l DHA with 2.8 mmol/l glucose was impaired, and DHA sensitivity of the KATP channels was reduced in beta cells of GK rats. From these results, we suggest that the intracellular site responsible for impaired glucose metabolism in pancreatic beta cells of GK rats is located in the glycerol phosphate shuttle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418371
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Reduced sensitivity of dihydroxyacetone on ATP-sensitive K+ channels of pancreatic beta cells in GK rats (1994)
    Springer
    Diabetologia 37 (1994), S. 1082-1087 
    Details
    ISSN: 1432-0428
    Keywords: Key words Dihydroxyacetone ; ATP-sensitive K+ channels ; GK rat ; glycerol phosphate shuttle ; pancreatic beta cell.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the GK (Goto-Kakizaki) rat, a genetic model of non-insulin-dependent diabetes mellitus, glucose-induced insulin secretion is selectively impaired. In addition, it has been suggested by previous studies that impaired glucose metabolism in beta cells of the GK rat results in insufficient closure of ATP-sensitive K+ channels (KATP channels) and a consequent decrease in depolarization, leading to a decreased insulin release. We have recently reported that the site of disturbed glucose metabolism is probably located in the early stages of glycolysis or in the glycerol phosphate shuttle. In the present study, in order to identify the impaired metabolic step in diabetic beta cells, we have investigated insulin secretory capacity by stimulation with dihydroxyacetone (DHA), which is known to be directly converted to DHA-phosphate and to preferentially enter the glycerol phosphate shuttle. In addition, using the patch-clamp technique, we also have studied the sensitivity of DHA on the KATP channels of beta cells in GK rats. The insulin secretion in response to 5 mmol/l DHA with 2.8 mmol/l glucose was impaired, and DHA sensitivity of the KATP channels was reduced in beta cells of GK rats. From these results, we suggest that the intracellular site responsible for impaired glucose metabolism in pancreatic beta cells of GK rats is located in the glycerol phosphate shuttle. [Diabetologia (1994) 37: 1082–1087]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418371
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    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The development of spatial resolving power of lateral geniculate neurones in kittens (1978)
    Springer
    Experimental brain research 31 (1978), S. 193-206 
    Details
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Development ; Visual acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial resolving power and receptive field properties of ‘sustained’ cells in layers A and A1 of the lateral geniculate nucleus (LGN), which received inputs from the area centralis of the retina in kittens of 3–16 weeks of age had been studied. The basic concentric organisation of receptive fields of ‘sustained’ LGN cells receiving inputs from the area centralis appeared to be already laid out at 3 weeks in kittens. Spatial resolving power of the cells determined using the highest spatial frequency of a sinusoidal grating resolved by cells as a measure of cellular visual acuity, however, developed gradually to the level of adult LGN cells during the sensitive period (3–12 weeks). Although this development occurred alongside the process of maturation of ocular alignment and the refractive state of the eyes, following the clearing of the embryonic vasculature of the ocular media from the 4th week onward, it depended on the enhancement of distinct inhibitory surround mechanisms taking place during the 6th–11th week. The course of development of spatial resolution of ‘sustained’ LGN cells receiving inputs from the area centralis of the retina runs parallel with the developmental curve of visual acuity in kittens obtained by visually evoked responses or by behavioural techniques by previous workers. The neural mechanisms which subserve high visual acuity are therefore already determined at the LGN before the inputs of the two eyes are mixed at the visual cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237599
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Loss of spatial resolution of lateral geniculate nucleus neurones in kittens raised with convergent squint produced at different stages in development (1978)
    Springer
    Experimental brain research 31 (1978), S. 207-220 
    Details
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Convergent squint ; Visual development ; Amblyopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In twelve kittens, convergent squint was surgically produced at either 3, 6, 8, 10, 13, or 16 weeks. When these kittens reached the age of 4–8 months, the spatial resolution of ‘sustained’ cells which received inputs from the area centralis in layers A and A1 of both the left and right lateral geniculate nucleus (LGN) was measured under nitrous oxide/halothane anaesthesia, using the highest spatial frequency of a sinusoidal grating resolved by cells as a measure of cellular visual acuity. Spatial resolution of cells fed by the squinting eye's area centralis was poorest in the kittens in which the squint was produced at 3 weeks. The resolution of the cells driven by the area centralis of the squinting eye gradually improved for the kittens in which the squint was produced at progressively later stages. There was no effect of convergent squint on the resolving power of cells in the kittens in which squint was produced at 13 weeks and 16 weeks. The developmental curve of spatial resolution of LGN cells obtained from normal kittens of different ages was found to fit very closely with a plot of the spatial resolution of cells driven by the squinting eye against age at squint production. These results suggest that the loss of spatial resolution (amblyopia) in the eye with convergent squint is due to the arrest of development of spatial resolution during the sensitive period in early postnatal life. Clinical implications are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237600
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    Paper (German National Licenses)
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