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Biomedical subjects

P Albert

Publications and source records attributed to P Albert.

At least 55 records · Page 3Linked to original sources
PubMed1990

Differential coupling of dopaminergic D2 receptors expressed in different cell types. Stimulation of phosphatidylinositol 4,5-bisphosphate hydrolysis in LtK- fibroblasts, hyperpolarization, and cytosolic-free Ca2+ concentration decrease in GH4C1 cells.

Dopaminergic D2 receptors are widely regarded as typical inhibitory receptors, as they both inhibit adenylyl cyclase and decrease the cytosolic free Ca2+ concentration ([Ca2+]i) by activating K+ channels. A D2 receptor has recently been cloned (Bunzow, J. R., Van Tol, H. H. M., Grandy, D. K., Albert, P., Salon, J., Christie, M. D., Machida, C. A., Neve, K. A., and Civelli, O. (1988) Nature 336, 783-787) and expressed in two different cell lines, pituitary GH4C1 cells and Ltk- fibroblasts, where it has been shown to induce inhibition of adenylyl cyclase. We have investigated the additional effector systems coupled to this receptor. The responses observed in the two cells lines, which express similar levels of receptors (0.5-1 x 10(5)/cell), were surprisingly different. In GH4C1 cells D2 receptors failed to affect phosphoinositide hydrolysis and induced a decrease of [Ca2+]i. This latter effect appears to be mediated by hyperpolarization, most likely due to the activation of K+ channels. In striking contrast, in Ltk- fibroblasts the D2 receptor induced a rapid stimulation of inositol(1,4,5)-trisphosphate (+73% at 15 s) followed by the other inositol phosphates, and an immediate increase of [Ca2+]i due to both Ca2+ mobilization from internal stores and influx from the extracellular medium. In both GH4C1 and Ltk- cells, the D2 receptor response was mediated by G protein(s) sensitive to pertussis toxin. The increases of inositol trisphosphate and [Ca2+]i observed in Ltk- cells required dopamine concentrations only slightly higher than those inhibiting adenylyl cyclase (EG50 = 25, 29, and 11 nM, respectively) and were comparable in magnitude to the responses induced by the endogenous stimulatory receptor agonists, thrombin and ATP. The results demonstrate that in certain cells D2 receptors are efficiently coupled to the stimulation of phosphoinositide hydrolysis. The nature of receptor responses appears therefore to depend on the specific properties not only of the receptor molecule but also of the cell type in which it is expressed.

Adenosine Triphosphate↗
PubMed1990

A study on the venous drainage of 150 cerebral arteriovenous malformations as related to haemorrhagic risks and size of the lesion.

In this paper we study the venous drainage of 150 cerebral arteriovenous malformations (AVM), correlating the number of efferent veins with the symptoms of clinical onset and with the size of the lesions. Statistical analysis demonstrates that those AVM's which in the angiograms show only one draining vein have a high risk of haemorrhage. As the number of drainage veins increases, this bleeding risk decreases, becoming quite low in angiomas with multiple drainage veins, which we denominate "medusa-head angiomas". Statistics also demonstrate that small angiomas (less than 2 centimeter on diameter) usually have only one drainage vein, thus carrying a high risk of haemorrhage. As their size increase, so do the number of veins, and the possibility of haemorrhage decreases.

Adolescent↗
PubMed1990

Prednisolone promotes the secretion of progesterone and oestradiol by luteinised granulosa cells independent of human chorionic gonadotropin.

An in vitro model based on luteinised granulosa cells gained during an in vitro fertilisation programme examines the question of whether prednisolone, and thus glucocorticoids in general, are capable of exerting an influence on the secretion of oestradiol and progesterone. It can be demonstrated that prednisolone leads to dosage-dependent increases in the concentration of both steroids, even independently of concurrent stimulation by human chorionic gonadotropin. A similar mechanism for aromatase activity of human adipose cells is suggested.

Chorionic Gonadotropin↗
PubMed1989

Flow cytofluorimetric determination of protein distribution throughout the cell cycle.

Quantitative treatment of multiparametric determination on cells using flow cytofluorometry was made possible by the development of a computer program that allows the relative quantification of a specific protein as a function of the position of cells during the cell cycle. This type of analysis provides interesting information about the distribution of a given protein throughout the cell cycle. Four examples showing the distribution of specific proteins illustrate such a quantification during the cell cycle in two different cell lines. The program also allows for the handling of a series of histograms obtained by the analysis of protein distribution as a function of DNA content in relation to a third parameter. To illustrate possible applications for this program, the evolution of the distribution of two proteins, the oncoprotein p53 and the histone H1(0), during the induced differentiation of murine erythroleukemia cells has been studied.

Animals↗
PubMed1989

[Initial experiences with hysterosalpingoscintigraphy in normal and pathologic fallopian tube passage].

A prospective study in 38 patients was designed to evaluate the efficacy and reliability of radionuclide hysterosalpingoscintigraphy (HSS) using 99mTc labelled human albumin macroaggregates (HAMA). Following application in the posterior vaginal fornix at the time of ovulation, HAMA normally migrate spontaneously through the uterus and tubes and may be identified after 20 min (range 5-90 min) in the uterine cavity and after 2 hrs (range 40 min - 3 hrs) in the free pelvis, using a gamma camera. When correlated with the findings of conventional contrast hysterosalpingography (HSG), the radionuclide procedure yielded comparable results in females with patent or clearly obstructed tubes. Using 8-10 MBq 99mTc, radiation exposure was estimated to be 0.75 cGy per ovary, which is considerably less than the mean dose absorbed with HSG. As the HSS procedure imitates the migration of spermatozoa by the means of an inert tracer, it allows a direct insight in the mechanisms of passive transport taking place in the uterus and tubes at the period of ovulation. Thus, it reflects the physiological state of the female reproductive tract. On the basis of the scintigraphic findings, equivocal results on HSG have to be re-evaluated, as tubes, which are anatomically patent under high pressure, may be functionally deficient.

Adult↗
PubMed1989

[Is intravenous urography indispensable in evaluating a bladder emptying disorder?].

Two patients with disorders of bladder emptying (dysuria, pollakiuria) were treated by endourethral resection after being investigated by ultrasonography without intravenous pyelography. Intravenous pyelography performed subsequently due to persistence and even deterioration of the bladder emptying disorders revealed the diagnosis and allowed treatment of renal tuberculosis. Intravenous pyelography is therefore an essential part of the assessment of patients with prostatic symptoms.

Aged↗
PubMed1989

[Functional and urodynamic study of cecocystoplasties with or without detubation].

The authors analyse and compare the clinical and urodynamic results of 16 tubed caecocystoplasties and 5 detubed ileocaecocystoplasties. The urodynamic assessments were performed between 2 months and up to 4 years after the operation. After a period of about 6 months, there was a functional difference between these two types of reservoir. The loss of pressure peaks in detubed reservoirs is not sufficient to ensure complete nocturnal continence. Neovesico-sphincteric synergy is responsible for real sphincteric self-re-education. Rationally, a detubing procedure in bladder replacement is only desirable in the case of a "deficient" sphincter.

Cecum↗
PubMed1989

[Extra-corporeal lithotripsy (EDAP LT 01) in urinary lithiasis].

Five hundred and twenty six extracorporeal lithotripsies have been performed for renal and ureteric stones. Using low frequencies (1.25 to 2.5 cycles per second), extracorporeal lithotripsy was performed without anaesthesia and without premedication in 85% of cases. 91.9% of patients treated were followed and reviewed after one and three months: 292 (55%) were successes, 124 (22.5%) obtained partial results, 122 (22.5%) were failures. The best results were obtained in stones less than 20 mm in diameter. The results could only be improved by a second session of extracorporeal lithotripsy. Scintigraphic scars observed after high frequency lithotripsy and not observed after low frequency lithotripsy were again seen after renewal of the firing head.

Evaluation Studies as Topic↗
PubMed1988

Application of bromodeoxyuridine incorporation measurements to the determination of cell distribution within the S phase of the cell cycle.

Flow cytofluorimetric measurement of incorporated bromodeoxyuridine, using a double-stained cell population, allows the determination of the distribution of cells along the cell cycle. We have developed a simple computer program for the direct treatment of 64 x 64 channel histograms. This analysis appears to provide interesting data about the distribution of cells in the various phases of the cell cycle, namely the S phase. Two examples have been chosen to illustrate possible fields for the application of such a program. Comparison of two cell lines such as friend murine erythroleukemia cells (MELC) and fibroblasts FR3T3 cells has shown that this analysis can be used for cell-cycle characterization of a given cell line. The program also allows the differential analysis of cell distribution along the cell cycle as a function of a given parameter. This possibility has been applied to study the variation of cell-cycle parameters as a function of the time of induced differentiation of MELC and reveals changes in the distribution of the cells along the various phases of the cell cycle, namely in the S phase.

Animals↗
PubMed1988

Treatment of carotid-cavernous fistulas by embolization of the cavernous sinus through venous affluents or direct puncture.

Eight patients with nine carotid-cavernous fistulas (CCF), one of them bilateral, have been treated in our Department by embolization of the venous components of the cavernous sinus, either through one of its venous effluents or by direct puncture of the sinus, in an effort to preserve the internal carotid artery (ICA). Five of the fistulas were of traumatic origin and four were spontaneous. In two cases the cavernous sinus was embolized through bridging temporal veins, and in another two cases embolization was carried out by catheterization of the cavernous sinus via the superior ophthalmic vein, while in the remaining five cases it was performed by direct puncture of the lateral wall of the sinus. The embolizing materials employed were bone wax mixed with an oily iodised contrast media, small pieces of oxidized cellulose or gelfoam vehicled by saline solution, and fibrin sealant. Obliteration of the CCF was complete in all but one case, in which this was accomplished only partially. On six occasions carotid patency was maintained, while in two patients failure of the technique made trapping of the ICA necessary. In one patient the ICA was ligated prior to the embolization of the cavernous sinus. The surgical techniques employed and the results achieved are exposed.

Adult↗
PubMed1988

Changes induced by caffeine, theophylline and theobromine on calcium uptake, respiration and ATP levels in rat-liver mitochondria.

1. The inhibition of calcium uptake and cellular respiration depend on the concentration of the compounds as shown by the concentration-effect curves. 2. The concentrations at which 50% inhibition of the transport of calcium takes place (caffeine 45 mM, theophylline 12 mM, theobromine, 4 mM) do not coincide exactly with those that produce the same effect on cellular respiration (caffeine 60 mM, theophylline 22 mM, theobromine 8 mM). 3. ATP concentrations under different conditions were also determined; a decrease in their value induced by the drugs was observed. No significant differences were observed, however, between the effect produced by the methyl-xanthines. 4. These findings suggest that these compounds are able to affect in some way the maintenance of energy gradients linked to the effects studied.

Adenosine Triphosphate↗