Biomedical subjects
Publications and source records attributed to G Meyer.
In a 61-year-old woman recurrent bacterial infections were caused by immune neutropenia which was resistant to high-dose cortisone and plasmapheresis. However, high-dose intravenous 7S-immunoglobulin therapy (30 g for 6 days) induced a long-term remission for 35 months. This treatment modality is safe and should be used as a first-line agent.
The morphology and the spatial arrangement of neurons in the primary motor cortex (area 4) of the adult human brain have been investigated by the Golgi method. The human motor cortex displays a great variety of pyramidal and nonpyramidal cells, expressed as important differences in soma shape and size, and in the dimensions and the distribution of dendritic trees, which are described in detail. The neuronal composition of each layer and the white matter is analyzed. In sublayers III b and c, the somata and dendritic trees of pyramidal and nonpyramidal cells are grouped into columnar aggregations, 100-300 micron wide and separated by cell-sparse spaces of 50-100 micron width. Within the aggregations, the apical dendrites of pyramidal cells form several bundles. The dendrites of most nonpyramidal cells do not surpass the columnar width. Sections in different planes reveal that the columnar aggregations observed in sections perpendicular to the long axis of the precentral gyrus are actually the cross-sectioned representatives of elongate strips running parallel to the long axis of the gyrus. The dendrites and somata of pyramidal cells in layers III and V show a preferential orientation in the same direction, parallel to the main axis of the gyrus. In layers II, IV, and V, aggregations like those in layer III are not recognizable; however, in layer V, loose assemblages of neurons of all sizes group around the giant Betz cells. Layer VI has a radial appearance due to the radii of myelinated fibers entering and leaving the white matter. The vertical, columnar organization of layer III and the asymmetry of somata and dendritic trees are not observed consistently throughout area 4, but are more pronounced at the boundary of the precentral gyrus and the central sulcus.
The early postnatal development of neuropeptide Y-containing neurons in the visual cortex of the cat was analyzed. Immunohistochemistry reveals several stages of morphological differentiation and degeneration. Completely undifferentiated neurons have very small somata with nuclei surrounded by a thin rim of cytoplasm and processes unclearly differentiated into dendrites and axons. Processes bear growth cones. Differentiating neurons show an increase in soma size and complexity of processes. Axons are recognizable. Fully differentiated neurons have well-defined axonal and dendritic patterns. Degenerating neurons are identified by thick, heavily beaded processes covered by hairy appendages and vacuolar inclusions in the somata. Cell death is expressed by shrunken somata and lysed, fragmented processes. According to their postnatal time course of differentiation and/or degeneration, NPY-immunoreactive neurons, which form several morphologically distinct cell types, are grouped into 3 neuronal populations. (1) Pseudopyramidal cells, bitufted "rectangular" cells with wide dendritic fields, unitufted cells, and small multipolar cells are located in the gray matter and have a rather primitive morphology resembling cell types found in lower vertebrate cortex and tectum. They constitute a first transient neuronal population, because all neurons are fully differentiated at birth and become largely eliminated by postnatal day (P) 12. (2) Axonal loop cells are mainly located in the white matter. Their most prominent feature is an often long hairpin loop formed by either the main axon itself or by a major collateral. The axonal branches pass through the cortex to connect the white matter and layer I. Axons do not form local plexusses and terminal elements in the gray matter. Neurons differentiate perinatally, form a first peak from P6 to P10, followed by a decrease in cell number and innervation density at P12, followed by a second peak from P15 to P20. After P20 the number of axonal loop cells steadily decreases, and they become eliminated by P48. (3) A third population consists of neurons with a higher degree of axonal ramification and a variety of axonal patterns. Early members are located mainly at the layer VI/white matter border, differentiate during the first postnatal week, and give rise to a diffuse innervation of the gray matter without forming specific terminal elements. Some of the early axonal patterns persist into adulthood, whereas others are not found in the adult brain.(ABSTRACT TRUNCATED AT 400 WORDS)
The apical membranes of rabbit gallbladder epithelial cells were isolated by treating the homogenate with Ca2+ or Mg2+ and centrifuging the suspension in Percoll gradient. In this way brush-border membranes were obtained with enrichment factors ranging between 10 and 20 and yields of 15-30%. A second method is described with which membranes were isolated, without any preliminary treatment, first by differential centrifugation, then with Percoll gradient; the final membrane enrichment was over 15, however the yield was very low (3%). Many possible enzymatic markers of the apical plasma membrane were investigated: L-gamma-glutamyltransferase, alkaline phosphatase, leucine aminopeptidase, sucrase. The first appears to be that of choice. Apical membrane fraction could be also evidenced by autofluorescence or by labeling with Lotus tetragonolobus lectin. Preliminary experiments showed that apical plasma membranes isolated in this way form vesicles.
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The various forms of bronchoplastic and angioplastic procedures are the best means of avoiding pneumonectomy. Essential indications are limited respiratory reserve and central site of a malignancy. In a retrospective study 248 broncho- and angioplastic operations carried out in the years 1973 to 1983 were analyzed. Reference date for the analysis of survival was January 1986. In consequence the minimum period of follow-up was two years. For all patients (n = 248) the 5-year-survival was 22% with a 30-day-lethality of 13%. The 5-year-survival of all bronchial sleeve resections operated radically (stage I and II of the TNM-classification) (n = 44) was 42% with a 30-day-lethality of 7%. The 5-year-survival of all bronchoplastic operations of stage I and II (n = 88) was 38% with a 30-day-lethality of 14%. Improved suture material and surgical techniques caused a reduction of operative lethality from 23% to 8% during the described period. In the first thirty postoperative days the following complications caused death: Hemoptysis (n = 5), insufficiency of the anastomosis (n = 3), right heart failure (n = 5), pulmonary embolism (n = 4) and sepsis (n = 1).
In 21 patients after combined chest wall and lung metastasis resection a median survival time of 11 months was found independent of the degree of the chest wall infiltration. Only 1 patient with metastasis from a testicular teratoma survived 5 years and is tumor free. There was no 30-day-lethality. The main indications are complications such as exulceration and pain. In spite of the poor prognosis a prolongation of survival time with improved quality of life may be achieved. In rare cases cure is possible by combined tumor reductive surgery and chemotherapy.
Cl- influx at the luminal border of the epithelium of rabbit gallbladder was measured by 45-sec exposures to 36Cl- and 3H-sucrose (as extracellular marker). Its paracellular component was evaluated by the use of 25 mM SCN- which immediately and completely inhibits Cl- entry into the cell. Cellular influx was equal to 16.7 mu eq cm-2 hr-1 and decreased to 8.5 mu eq cm-2 hr-1 upon removal of HCO3- from the bathing media and by bubbling 100% O2 for 45 min. When HCO3- was present, cellular influx was again about halved by the action of 10(-4) M acetazolamide, 10(-5) to 10(-4) M furosemide, 10(-5) to 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS), 10(-3) M amiloride. The effects of furosemide and SITS were tested at different concentrations of the inhibitor and with different exposure times: they were maximal at the concentrations reported above and nonadditive. In turn, the effects of amiloride and SITS were not additive. Acetazolamide reached its maximal action after an exposure of about 2 min. When exogenous HCO3- was absent, the residual cellular influx was insensitive to acetazolamide, furosemide and SITS. When exogenous HCO3- was present in the salines, Na+ removal from the mucosal side caused a slow decline of cellular Cl- influx; conversely, it immediately abolished cellular Cl- influx in the absence of HCO3-. In conclusion, about 50% of cellular influx is sensitive to HCO3-, inhibitable by SCN-, acetazolamide, furosemide, SITS and amiloride and furthermore slowly dependent on Na+. The residual cellular influx is insensitive to bicarbonate, inhibitable by SCN-, resistant to acetazolamide, furosemide, SITS and amiloride, and immediately dependent on Na+. Thus, about 50% of apical membrane NaCl influx appears to result from a Na+/H+ and Cl-/HCO3- exchange, whereas the residual influx seems to be due to Na+-Cl- cotransport on a single carrier. Whether both components are simultaneously present or the latter represents a cellular homeostatic counter-reaction to the inhibition of the former is not clear.
In the epithelium of rabbit gallbladder, in the nominal absence of bicarbonate, intracellular Cl- activity is about 25 mM, about 4 times higher than intracellular Cl- activity at the electrochemical equilibrium. It is essentially not affected by 10(-4) M acetazolamide and 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS) even during prolonged exposures: it falls to the equilibrium value by removal of Na+ from the lumen without significant changes of the apical membrane potential difference. Both intracellular Cl- and Na+ activities are decreased by luminal treatment with 25 mM SCN-; the initial rates of change are not significantly different. In addition, the initial rates of change of intracellular Cl- activity are not significantly different upon Na+ or Cl- entry block by the appropriate reduction of the concentration of either ion in the luminal solution. Luminal K+ removal or 10(-5) M bumetanide do not affect intracellular Cl- and Na+ activities or Cl- influx through the apical membrane. It is concluded that in the absence of bicarbonate NaCl entry is entirely due to a Na+-Cl- symport on a single carrier which, at least under the conditions tested, does not cotransport K+.
During early postnatal development glutamate decarboxylase (GAD)-immunoreactive (ir) neurons are present in the white matter of the kitten occipital cortex. Most neurons are located below layer VI in the 'upper subplate' zone, others are located deeper in the white matter. In animals at postnatal (P) days 10 and 20 we classified two cell types on the basis of their axonal pattern. One type, the axonal loop cells, displays loops of 180 degrees formed either by the main axonal stem or by a major recurrent collateral. The neurons do not form terminals in the white matter. The other type, the local axon cells, have frequently branching axons giving rise to terminal varicosities contacting other white matter neurons in a basket-like manner. The local cells form terminal plexuses which occupy the white matter of younger kittens and are concentrated in a 100-150 micron wide zone subjacent to layer VI. In P48 kittens, density and width of the plexus is reduced and axonal loop cells and the local axon cells have disappeared. Some GAD-ir white matter neurons observed at this age have large fusiform somata and straight projecting axons. The origin and fate of the early postnatal white matter neurons will be discussed.
A case is reported of voluntary acute carbofuran poisoning. The clinical presentation was suggestive and i.v. atropine sulphate was immediately administered. In the absence of a specific antidote, curarization with pancuronium bromide with assisted ventilation and diazepam sedation was used to treat the persistent nicotinic myoclonic state. No rhabdomyolysis was observed.
It is well established that rat ovarian granulosa cells produce tissue plasminogen activator (tPA). The synthesis and secretion of the enzyme are induced by gonadotropins, and correlate well with the time of follicular rupture in vivo. We have found that in contrast, mouse granulosa cells produce a different form of plasminogen activator, the urokinase-type (uPA). As with tPA synthesis in the rat, uPA production by mouse granulosa cells is induced by gonadotropins, dibutyryl cAMP, and prostaglandin E2. However, dexamethasone, a drug which has no effect on tPA synthesis in rat cells inhibits uPA synthesis in the mouse. Results of these determinations made in cell culture were corroborated by examining follicular fluid, which is secreted in vivo predominantly by granulosa cells, from stimulated rat and mouse ovarian follicles. Rat follicular fluid contained only tPA, and mouse follicular fluid only uPA, indicating that in vivo, granulosa cells from the two species are secreting different enzymes. The difference in the type of plasminogen activator produced by the rat and mouse granulosa cells was confirmed at the messenger RNA level. After hormone stimulation, only tPA mRNA was present in rat cells, whereas only uPA mRNA was found in mouse cells. Furthermore, the regulation of uPA levels in mouse cells occurs via transient modulation of steady-state levels of mRNA, a pattern similar to that seen with tPA in rat cells.
We have studied the afferent connections of the inferior colliculus of the albino mouse. Our results show: First, the afferent connections of the inferior colliculus in the mouse are similar to those of other species, however, some differences exist. Second, there is a different projection pattern to the dorsal cortex and the central nucleus of the inferior colliculus; the dorsal cortex receives fibers essentially from auditory centers, while the central nucleus also receives afferents from other structures not related to the auditory system. Third, an interesting parallel may be established between the connections of the inferior colliculus and those of the superior colliculus.
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Explore the source record for details and available documents.