Thermodynamic Description of Synergy in Solvent Extraction: II Thermodynamic Balance of Driving Forces Implied in Synergistic Extraction.

In the second part of this study, we analyze the free energy of transfer in the case of synergistic solvent extraction. This free energy of the transfer of an ion in dynamic equilibrium between two coexisting phases is decomposed into four driving forces combining long-range interactions with the classical complexation free energy associated with the nearest neighbors. We demonstrate how the organometallic complexation is counterbalanced by the cost in free energy related to structural change on the colloidal scale in the solvent phase. These molecular forces of synergistic extraction are driven not only by the entropic term associated with the tight packing of electrolytes in the solvent and by the free energy cost of coextracting water toward the hydrophilic core of the reverse aggregates present but also by the entropic costs in the formation of the reverse aggregate and by the interfacial bending energy of the extractant molecules packed around the extracted species. Considering the sum of the terms, we can rationalize the synergy observed, which cannot be explained by classical extraction modeling. We show an industrial synergistic mixture combining an amide and a phosphate complexing site, where the most efficient/selective mixture is observed for a minimal bending energy and maximal complexation energy.

[Diagnosis of aphasia on the stroke unit]. / Aphasiediagnostik auf der Stroke Unit.

The first weeks of aphasia are called the acute stage. The rapid change and possible fluctuation of language deficits at that stage as well as concurrent phenomena such as drive disturbances, apraxia, or perseveration pose particular requirements for aphasia diagnosis. Professional language diagnosis in a stroke unit is necessary for detailed description of the language deficits, differential diagnosis of concomitant cognitive or functional disturbances, and a description of the dynamics of the deficits to start with specific therapeutical interventions as soon as the patient's health status allows. There are three published German aphasia test batteries especially constructed for diagnosis of acute aphasia language deficits. They differ with respect to content and pragmatic aspects and offer a range of applications, including the diagnosis of aphasia, recommendations for therapy, and the use in scientific studies.

[Copying and free drawing by patients with Alzheimer disease of different dementia stages]. / Abzeichnen und freies Zeichnen bei Alzheimer-Patienten mit unterschiedlicher Demenzausprägung.

In this study we assessed the drawing abilities in 37 patients with probable Alzheimer's disease according to NINCDS-ADRDA criteria. Drawing abilities (drawing: house, flower, clock; Rey-Osterrieth figure; copying: MMST-figure; Rey-Osterrieth figure) were quantified with different rating schemes and related to other neuropsychological assessments. All patients underwent a positron emission tomography with 18-FDG. Drawing performance was highly correlated with severity of dementia--expressed in MMST scores (r = 0.78; p < 0.0001)--with visuo-spatial short-term memory (r = -0.69; p = 0.001), and writing abilities (r = -0.77; p < 0.0001). The summarized drawing score showed a statistically significant correlation with the rate of temporoparietal glucose metabolism measured with positron emission tomography and 18-FDG (r = 0.39; p = 0.017). In the drawings of AD patients omittings and simplifications were typical, whereas perseverations rarely occurred. In severely demented patients closing-in phenomenons could be described, too. A subgroup of AD patients with visuo-constructive impairment as the leading symptom could not be identified.

Concerted stimulation of rat granulosa cell deoxyribonucleic acid synthesis by sex steroids and follicle-stimulating hormone.

Although follicle-stimulating hormone (FSH) and estrogens are known to be the main physiological stimuli for the development of the ovarian follicle in mammals, their growth-promoting activity has not been clearly established "in vitro". Furthermore, experimental evidence indicates that FSH and estradiol can independently inhibit granulosa cell proliferation. The present study was aimed at examining the effect of sex steroids in combination with FSH, on DNA synthesis in rat granulosa cells cultured in completely defined medium. Estradiol and FSH, when added separately, produced a significant inhibition of [3H] thymidine incorporation. In contrast, a combination of a low dose of FSH (20 ng/ml) with estradiol (100 ng/ml) produced a shift in the period of maximal DNA synthesis from 96 to 48 h after plating. Dose response studies showed that estradiol effects were produced at physiological intraovarian concentrations (1-100 ng/ml), whereas the effects of FSH were biphasic, with high doses (200 ng/ml) being inhibitory. A similar biphasic dose response curve was observed with increasing concentrations of a cAMP derivative in the presence of maximally effective doses of either an aromatizable steroid (androstenedione), insulin or insulin-like growth factor I. Non-aromatizable androgens (5alpha-dihydrotestosterone, 5alpha-androstane 3alpha-17beta diol and androsterone) showed a potency comparable to that of estradiol. The effect of 5alpha-dihydrotestosterone was completely blocked by a specific antiandrogen (hydroxy-flutamide), indicating that it was mediated by the androgen receptor. The effects of estradiol and androgens were not additive. The interaction between estradiol and FSH was further amplified in the presence of a maximally effective dose of insulin. Data presented herein indicate that both estrogens and androgens are able to elicit a mitogenic response in purified granulosa cells, cultured in a completely defined medium, provided the cells are stimulated by a physiological dose of FSH. These results suggest that, during follicular development, the stimulus for granulosa cell proliferation is given by the concerted action of steroid and peptide hormones acting through different signalling pathways.

Strategies and structures in verbal fluency tasks in patients with Alzheimer's disease.

Reduced word production in verbal fluency tasks is a sensitive indicator for brain damage. Patients with Alzheimer's disease (AD) are supposedly more affected in semantic than in letter fluency, which is probably resulting from partially destroyed structure of semantic knowledge, whereas in letter fluency tasks the patients can use phonemic cues for searching. In this study, 21 patients with probable AD according to NINCDS-ADRDA criteria were examined on a verbal fluency task with F, A, S as initial letters, and a supermarket task. Performances were compared with a control group. Patients with AD showed lower word rate in all tasks than the control group. The difference was most significant in the supermarket task. Both groups produced most of the words in the supermarket task, followed by S, A and F. They both showed a percentuallikely distribution pattern of items into different supermarket categories. The items of the supermarket task were mostly ranged in clusters (patients with AD 70%, control group 83%). Patients with AD, however, on average, used fewer categories which they also filled with fewer items. In the F, A, S test, patients with AD mainly produced nouns, whereas the control group named nearly twice as many adjectives and verbs. In patients with AD word generation was highly correlated with degree of dementia, free recall of a verbal memory task, and the Token test. Low word production and qualitatively changed output in patients with AD might relate to an inefficient searching strategy, attentional deficits and/or degraded semantic knowledge.

Evidence for the production of a growth-inhibitory factor by human granulosa-luteal cells.

The factors involved in the inhibition of ovarian follicular cellular growth after the luteinizing hormone (LH) surge are poorly established. The aim of this study was to investigate the production of an inhibitory growth factor by human ovarian cells. Luteinized granulosa cells were obtained from an assisted fertilization program and were cultured in the presence or absence of follicle-stimulating hormone (FSH) and estradiol. Data obtained by cell counting showed that the number of human luteinized granulosa cells cultured in the presence of fetal bovine serum (10%) increased 1.8-fold within a 2-day period. In serum-free medium, human luteinized granulosa cells were able to incorporate 3H-thymidine, measured during consecutive 48 h periods. During all the periods tested (up to 7 days), low basal levels of thymidine incorporation were measured and were further reduced in the presence of FSH (200 ng/ml) and estradiol (500 ng/ml). To elucidate the possible production of an inhibitory growth factor, 3H-thymidine incorporation by rat granulosa cell cultures was measured in the presence of conditioned media (CM; from human granulosa cell cultures). In this system, FSH and estradiol elicited a tenfold increase in thymidine incorporation. The addition of CM (10% v/v collected on day 2) to FSH- and estradiol-treated granulosa cell cultures produced an inhibition (61%) of thymidine incorporation. The active factor in CM withstood freeze-thawing, was stable for several weeks at -20 degrees C, became unstable at 4 degrees C, and was heat labile and sensitive to proteolysis. Ultrafiltration using membranes with different molecular weight cutoffs suggested that the factor had a molecular weight > 30,000 dalton.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of follicle-stimulating hormone on insulin-like growth factor-I-stimulated rat granulosa cell deoxyribonucleic acid synthesis.

Granulosa cells from diethylstilbestrol-treated immature rats were cultured in a defined medium on collagen-coated plates. Thymidine incorporation was significantly increased by insulin (ED50, 656 +/- 110 ng/ml) and insulin-like growth factor (IGF-I; ED50, 95 +/- 10 ng/ml). Insulin and IGF-I stimulations were amplified by methylisobutylxanthine an inhibitor of phosphodiesterase activity. The effect of both peptides were also enhanced by low doses of (Bu)2cAMP (0.2-1 mM). In contrast, higher concentrations were inhibitory. Similarly, FSH produced a biphasic enhancement of the insulin- and IGF-I-stimulated DNA synthesis. Maximal effects (2- to 6-fold increases) were observed with the lower doses (2-20 ng/ml) of the gonadotropin. FSH enhancement of IGF-I-stimulated DNA synthesis was dependent on cell density. Plating densities of 3-5 x 10(5) cells/cm2 were required for a maximal interaction. It is concluded that FSH, acting through a cAMP-mediated pathway, may regulate granulosa cell proliferation by modulating the mitogenic effects of insulin and/or IGF-I.

A DNA topoisomerase I inhibitor blocks the differentiation of rat granulosa cells induced by follicle-stimulating hormone.

Follicle-stimulating hormone (FSH), acting through a cycle AMP-mediated mechanism, promotes differentiation of rat granulosa cells cultured in a defined medium. Camptothecin, a DNA topoisomerase I blocker, inhibited the increase in progesterone and oestradiol production stimulated by FSH. This effect was not due to non-specific inhibition of protein synthesis, as shown by measurement of [35S]methionine incorporation. A transient increase in DNA topoisomerase I activity was observed after 24 h of culture in the presence of FSH or dibutyryl cyclic AMP. Our results are consistent with a key role for DNA topoisomerase I in the modulation of gene expression by FSH in rat granulosa cells.

Hormonal regulation of rat granulosa cell deoxyribonucleic acid synthesis: effects of estrogens.

Although it is widely accepted that estrogens exert a major trophic effect on follicular growth, their mechanism of action has not been established. We examined the effect of estrogen treatment in vivo or in vitro on DNA synthesis in rat granulosa cells cultured under defined conditions (DMEM:F12, collagen-coated plastic wells). Treatment with diethylstilbestrol (DES) in vivo (silastic implants containing 5 mg DES) for at least 2 days was required to observe a significant stimulation of 3H-thymidine incorporation by insulin (1 microgram/ml) in culture. Rat thecal/interstitial cells (TI) were isolated from DES-treated rats and cultured under the same conditions as granulosa cells. Conditioned media from TI cells stimulated DNA synthesis in granulosa cell cultures (as much as twofold). This effect was markedly amplified by estradiol treatment (1 microgram/ml) of the TI cell cultures. Addition of estradiol to granulosa cell cultures enhanced the effect of conditioned medium from nontreated TI cells. Conditioned medium from estradiol-treated TI cells stimulated DNA synthesis in granulosa cells from both DES-treated and nontreated rats. Estradiol had no effect when added directly to purified granulosa cell cultures but stimulated 3H-thymidine incorporation in crude preparations of ovarian cells. The stimulatory effects of TI cell-conditioned medium and insulin were reflected in the final cell densities achieved after 9 days in culture. We conclude that the mitogenic actions of estrogens in the ovary involve sensitization of granulosa cells to locally present mitogens like insulin and a TI cell-derived growth factor.

Cyclic AMP inhibits fibronectin gene expression in a newly developed granulosa cell line by a mechanism that suppresses cAMP-responsive element-dependent transcriptional activation.

The main role of the ovarian granulosa cells is to nurse the oocyte and to produce estradiol and progesterone upon stimulation by gonadotropins. In fact, follicle-stimulating hormone (FSH) and luteinizing hormone control the expression of several genes during granulosa cell differentiation via cyclic AMP-dependent phosphorylations. Cyclic AMP stimulates transcription of genes that carry the cAMP-responsive element (CRE,5'TGACGTCA3') in their promoters. The fibronectin (FN) gene contains one CRE sequence at position -170. However, gonadotropins and cAMP inhibit FN gene expression in granulosa cells. To study the mechanism of the inhibition we developed a bovine granulosa cell line (BGC-1) that synthesizes estradiol in response to FSH and in which FSH and dibutyryl cAMP specifically decrease FN synthesis and its mRNA levels. The inhibitory effect (a) is not due to an alteration in FN mRNA stability, (b) requires upstream sequences other than CRE, located between positions -510 and -223, that are able to bind granulosa cell nuclear proteins, (c) is entirely dependent on the synthesis of intermediate proteins induced and or phosphorylated by cAMP, and (d) effectively suppresses the CRE-dependent transcriptional activation.

Improvement on the competitive binding assay for the measurement of cyclic AMP by using ammonium sulphate precipitation.

The protein-binding assay developed by Brown, Albano, Ekins, Sgherzi & Tampion [(1971) Biochem. J. 121, 561-562] and Brown, Ekins & Albano [(1972) Adv. Cyclic Nucleotide Res. 2, 25-40] was modified by using precipitation with (NH4)2SO4 of the protein-cyclic AMP complex instead of adsorption of the free nucleotide on charcoal. The half-life of the protein-cyclic AMP complex obtained in the presence of charcoal was lower than that of the (NH4)2SO4-precipitated complex. In consequence, owing to the great stability of the precipitated protein-cyclic AMP complex, this method allows more accurate and reproducible determinations.