Cortical Lewy bodies and Aß burden are associated with prevalence and timing of dementia in Lewy body diseases.

AIMS: Our main objective was to determine the neuropathological correlates of dementia in patients with Lewy body disease (LBD). Furthermore, we used data derived from clinical, neuropathological and genetic studies to investigate boundary issues between Dementia with Lewy bodies (DLB) and Parkinson's disease with (PDD) and without (PDND) dementia. METHODS: One hundred and twenty-one cases with a neuropathological diagnosis of LBD and clinical information on dementia status were included in the analysis (55 PDD, 17 DLB and 49 PDND). We carried out topographical and semi-quantitative assessment of Lewy bodies (LB), Aß plaques and tau-positive neuropil threads (NT). The APOE genotype and MAPT haplotype status were also determined. RESULTS: The cortical LB (CLB) burden was the only independent predictor of dementia (OR: 4.12, P < 0.001). The total cortical Aß plaque burden was an independent predictor of a shorter latency to dementia from onset of motor signs (P = 0.001). DLB cases had a higher LB burden in the parietal and temporal cortex, compared to PDD. Carrying at least one APOE ϵ4 allele was associated with a higher cortical LB burden (P = 0.02), particularly in the neocortical frontal, parietal and temporal regions. CONCLUSIONS: High CLB burden is a key neuropathological substrate of dementia in LBD. Elevated cortical LB pathology and Aß plaque deposition are both correlated with a faster progression to dementia. The higher CLB load in the temporal and parietal regions, which seems to be a distinguishing feature of DLB, may account for the shorter latency to dementia and could be mediated by the APOE ϵ4 allele.

Modeling of oleaginous fungal biofilm developed on semi-solid media.

An oleaginous fungus, Mortierella isabellina, able to transform efficiently sugar to storage lipid, was used as a model microorganism which develops a biofilm structure during the semi-solid fermentation process for the production of biodiesel from sweet sorghum. A mathematical model was developed to describe the fungal oil production in M. isabellina biofilm. The model describes diffusion and consumption of sugars and nitrogen of sweet sorghum and single cell oil production in a biofilm, which grows according to the kinetics of double-substrate limitation (sugars and nitrogen) with sugar inhibition. Experimental data from a previous experimental study were used to determine the kinetic parameters of the model. Maximum biofilm thickness and the percentage of lipid inside the biofilm were estimated using the model at 1892 µm and 15%, respectively. The proposed mathematical model could prove a useful tool for designing semi-solid fermentation processes.

Single cell oil production from rice hulls hydrolysate.

Rice hull hydrolysate was used as feedstock for microbial lipids production using the oleaginous fungus Mortierella isabellina. Kinetic experiments were conducted in C/N ratios 35, 44 and 57 and the oil accumulation into fungal biomass was 36%, 51.2% and 64.3%, respectively. A detailed mathematical model was used in order to describe the lipid accumulation process. This model was able to predict reducing sugar and nitrogen consumption, fat-free biomass synthesis and lipid accumulation. Neutral lipids constitute the predominant lipid fraction, while the major fatty acids were oleic, palmitic and linoleic acid. Fatty acids of long aliphatic chain were not detected, thus the microbial oil produced is a promising feedstock for biodiesel production.

Modeling of single-cell oil production under nitrogen-limited and substrate inhibition conditions.

Sweet sorghum extract was used as substrate for lipid accumulation by the oleaginous fungus Mortierella isabellina in batch cultures. Various initial sugar (13-91 g/L) and nitrogen (100-785 mg/L) concentrations resulting in various C/N (43-53) ratios were tested. Oil accumulation ranged between 43% and 51% corresponding to oil production from 2.2 to 9.3 g/L. A detailed mathematical model was developed. This model is able to adequately predict biomass growth, lipid accumulation, and sugar and nitrogen consumption. The model assumes that fungus growth is inhibited at high sugar concentrations. A set of kinetic experiments was used for model kinetic parameters estimation, while another set of experiments was used for model validation. The developed model could be generalized for similar systems of lipid accumulation and become a useful tool for reactor design for biofuel production.

Hydrogenotrophic denitrification of potable water: a review.

Several approaches of hydrogenotrophic denitrification of potable water as well as technical data and mathematical models that were developed for the process are reviewed. Most of the applications that were tested for hydrogenotrophic process achieved great efficiency, high denitrification rates, and operational simplicity. Moreover, this paper reviews the variety of reactor configurations that have been used for hydrogen gas generation and efficient hydrogen delivery. Microbial communities and species that participate in the denitrification process are also reported. The variation of nitrate concentration, pH, temperature, alkalinity, carbon and microbial acclimation was found to affect the denitrification rates. The main results regarding research progress on hydrogenotrophic denitrification are evaluated. Finally, the commonly used models and simulation approaches are discussed.

Semi-solid state fermentation of sweet sorghum for the biotechnological production of single cell oil.

A semi-solid fermentation process for the production of biodiesel from sweet sorghum is introduced. The microorganism used is the oleaginous fungus Mortierella isabellina, which is able to transform efficiently sugar to storage lipid. Kinetic experiments were performed at various water content percentages. The fungus consumed simultaneously sugars and nitrogen contained in sorghum and after nitrogen depletion the biomass growth was completed and oil accumulation began. Water content of 92% presented the highest oil efficiency of 11 g/100 g dry weight of substrate. The semi-solid process is shown to have certain advantages compared to liquid cultures or solid-state fermentation and gives oil of high quality.

Experimental and modelling study of drinking water hydrogenotrophic denitrification in packed-bed reactors.

The aim of this work was to study hydrogenotrophic denitrification in packed-bed reactors under draw-fill and continuous operation. Three bench-scale packed-bed reactors with gravel in different sizes (mean diameter 1.75, 2.41 and 4.03 mm) as support media were used, in order to study the effect of particle size on reactors performance. The maximum denitrification rate achieved under draw-fill operation was 4.4 g NO(3)(-)-N/ld for the filter with gravel of 2.41 mm. This gravel size was chosen to perform experiments under continuous operation. Feed NO(3)(-)-N concentrations and hydraulic loadings (HL) ranged between 20-200mg/l and 5.7-22.8m(3)/m(2)d, respectively. A comparison between the two operating modes showed that, for low HL the draw-fill operation achieved higher denitrification rates, while for high HL and intermediate feed concentrations (40-60 mg NO(3)(-)-N/l) the continuous operation achieved higher denitrification rates (4.67-5.65 g/ld). Finally, experiments with three filters in series (with gravels of 4.03, 2.41 and 1.75 mm mean diameter) were also performed under continuous operation. The maximum denitrification rate achieved was 6.2 g NO(3)(-)-N/ld for feed concentration of 340 mg/l and HL of 11.5m(3)/m(2)d. A model, which describes denitrification in packed-bed reactors, was also developed. The model predicts the concentration profiles of NO(3)(-)-N along filter height, in draw-fill as well as in continuous operation, satisfactorily.

Kinetics of pure cultures of hydrogen-oxidizing denitrifying bacteria and modeling of the interactions among them in mixed cultures.

In this study we report the isolation of four denitrifying bacteria from a batch reactor, where the progress of hydrogenotrophic denitrification was examined. Only three of the strains had the ability to use hydrogen as electron donor. In the present work, kinetic batch experiments were carried out in order to study the dynamic characteristics of pure and defined mixed cultures of hydrogen-oxidizing denitrifying bacteria, under anoxic conditions, in a defined synthetic medium, in the presence of nitrates. Kinetic models were developed and the kinetic parameters were determined from the batch experiments for each bacterium separately. The behavior of mixed cultures and the interactions between the bacteria were described using kinetic models based on the kinetic models developed for each bacterium separately and their predictions were compared with the results from mixed culture experiments. The mathematical models that were developed and validated in the present work are capable of describing the behavior of the bacteria in pure and mixed cultures, and in particular, the kinetics of nitrate and nitrite reduction and cell growth.

Coexistence of three microbial populations competing for three complementary nutrients in a chemostat.

We study a model of three microbial populations competing for three complementary nutrients in a single chemostat. By using methods of numerical bifurcation theory we analyze the model equations and determine the effect of the model parameters on the dynamics of the system. The main question to be answered is whether there exist conditions under which the three populations can coexist in a stable state in the chemostat. The analysis shows that coexistence can be obtained as a stable steady state but also as a stable periodic state for a wide range of operating conditions of the chemostat.

Computing operating diagrams of bioreactors.

The operating diagram of a bioreactor is an illustrative way to present the effect that the operating conditions have on its long-term behavior. It can be constructed if a mathematical model of the bioreactor is available. The procedure for constructing the operating diagram consists in analyzing the dynamic behavior of the system of the differential equations of the model. Some methods are described that can be used in computing operating diagrams of bioreactors. They are based on numerical bifurcation techniques for systems of differential equations. Both cases of bioreactors with constant and periodically varying operating conditions are considered.

Chaotic dynamics of a food web in a chemostat.

We analyze a mathematical model of a simple food web consisting of one predator and two prey populations in a chemostat. Monod's model is employed for the dependence of the specific growth rates of the two prey populations on the concentration of the rate-limiting substrate and a generalization of Monod's model for the dependence of the specific growth rate of the predator on the concentrations of the prey populations. We use numerical bifurcation techniques to determine the effect of the operating conditions of the chemostat on the dynamics of the system and construct its operating diagram. Chaotic behavior resulting from successive period doublings is observed. Multistability phenomena of coexistence of steady and periodic states at the same operating conditions are also found.

Oscillations of two competing microbial populations in configurations of two interconnected chemostats.

It is known that, when two microbial populations competing for a single rate-limiting nutrient are grown in a spatially uniform environment, such as a single chemostat, with competition being the only interaction between them, they cannot coexist, but eventually one of the two populations prevails and the other becomes extinct. Spatial heterogeneity has been suggested as a means of obtaining coexistence of the two populations. A configuration of two interconnected chemostats is a simple model of a spatially heterogeneous environment. It has been shown that, when Monod's model is used for the specific growth rates of the two populations, steady-state coexistence can be obtained in such systems for wide ranges of operating conditions. In the present work, we study a model of microbial competition in configurations of interconnected chemostats and we show that, if a substrate inhibition model is used for the specific growth rates of the two populations, coexistence in a periodic state is also possible. The analysis of the model is done by numerical bifurcation theory methods.

On the coexistence of three microbial populations competing for two complementary substrates in configurations of interconnected chemostats.

We examine the question of coexistence of three microbial populations competing for two complementary rate-limiting substrates in configurations of interconnected chemostats. It is known that coexistence of two populations competing for two rate-limiting substrates is possible in a single chemostat, but coexistence is not possible when three populations are involved. We examine whether coexistence of three populations becomes possible by considering configurations of two or three interconnected chemostats, thus allowing for effects of spatial heterogeneity. Computational analysis of the model equations indicates that in the case of two chemostats coexistence is possible only for specific discrete parameter values where the system is structurally unstable and therefore the coexistence state is not practically attainable, whereas in the case of three chemostats coexistence is possible for a whole range of parameter values where the system is structurally stable and therefore the coexistence state can be realized in practice.

Defective regulation of glycoprotein free alpha-subunit in males with isolated gonadotropin-releasing hormone deficiency--a clinical research center study.

During long term replacement with a GnRH regimen that restores their gonadotropin and sex steroid levels to normal, men with idiopathic hypogonadotropic hypogonadism (IHH) exhibit excessive secretion of pituitary free alpha-subunit (FAS). To characterize further the dose and duration of exogenous GnRH required to elicit this response, FAS, LH, FSH, and testosterone were determined during the first 8 weeks of GnRH administration in 10 men with IHH. The GnRH dose was increased stepwise every 2 weeks from 5 to 100 ng/kg every 2 h. Hormonal responses were compared with normative data for both pubertal boys and adult men. Low baseline levels of LH (mean +/- SEM, 0.9 +/- 0.03 IU/L), FSH (2.5 +/- 0.4 IU/L), FAS (148 +/- 21 ng/L), and testosterone (2.5 +/- 0.3 nmol/L) increased progressively after GnRH replacement. Mean FAS levels and pulse amplitudes significantly exceeded those in normal adult men by 4-6 weeks when their LH responses to GnRH administration remained below adult norms. By week 8 (50 ng GnRH/kg every 2 h), mean levels of LH, FSH, and FAS (13.7 +/- 2.1 IU/L, 15.4 +/- 4.0 IU/L, 627 +/- 75 ng/L, respectively) significantly exceeded adult male concentrations (P < 0.03). However, mean LH and FSH concentrations were not significantly different from midpubertal controls, in whom FAS levels were comparable to those in normal adults, verifying the excessive nature of FAS secretion relative to intact gonadotropins in the IHH patients. As this imbalance between FAS and dimeric gonadotropin secretion was established early in the current study when low doses of GnRH presumably resulted in low levels of receptor occupancy in vivo, it does not appear to result from partial pituitary desensitization induced by pharmacological GnRH stimulation. Rather, it appears to represent an inherent property of the GnRH-deficient state that is unmasked when GnRH input to the pituitary is restored. Further work will be necessary to elucidate the mechanism of this apparent defect in FAS regulation in GnRH-deficient men.

Coexistence of three competing microbial populations in a chemostat with periodically varying dilution rate.

Coexistence of three microbial populations engaged in pure and simple competition is not possible in a chemostat with time-invariant operating conditions under any circumstances. It is shown that by periodic variation of the chemostat dilution rate it is possible to obtain a stable coexistence state of all three populations in the chemostat. This is accomplished by performing a numerical bifurcation analysis of a mathematical model of the system and by determining its dynamic behavior with respect to its operating parameters. The coexistence state obtained in the periodically operated chemostat is usually periodic, but cases of quasi-periodic and chaotic behavior are also observed.

Gonadotropin-releasing hormone antagonist versus agonist administration in women undergoing controlled ovarian hyperstimulation: cycle performance and in vitro steroidogenesis of granulosa-lutein cells.

OBJECTIVES: We sought to determine the effectiveness of a gonadotropin-releasing hormone antagonist compared with an agonist in suppressing a spontaneous luteinizing hormone surge in women undergoing controlled ovarian hyperstimulation for in vitro fertilization and gamete intrafallopian transfer and to examine whether in vivo administration of these analogs effects granulosa-lutein cells steroidogenesis in vitro. STUDY DESIGN: This prospective case-control study included 30 healthy women undergoing ovarian hyperstimulation with human menopausal gonadotropins. Fifteen women received the Nal-Glu antagonist, 5 mg intramuscularly daily, when the lead follicle was > or = 15 mm or serum estradiol level was > or = 500 pg/ml. The control group included 15 women who underwent oocyte retrieval on the same day as the study subjects and were given the agonist leuprolide acetate, 250 micrograms subcutaneously daily, starting on cycle day 1. Granulosa-lutein cells were purified from follicular aspirates from six subjects and six controls and cultured in parallel, evaluating basal progesterone production, progesterone response to follicle-stimulating hormone or luteinizing hormone and aromatase activity. RESULTS: No difference was demonstrated in the total amount of gonadotropins received by the two groups. Overall, the gonadotropin-releasing hormone antagonist was given for only 2.5 +/- 0.2 (mean +/- SEM) days before human chorionic gonadotropin administration. The antagonist group showed significantly lower levels of serum luteinizing hormone than did the agonist group, 1.0 +/- 0.2 versus 4.2 +/- 0.5 mIU/ml (p = 0.0001) on the day of human chorionic gonadotropin administration. Serum estradiol levels were significantly lower in the antagonist than the agonist group, 820 +/- 120 versus 1361 +/- 110 pg/ml (p = 0.003) on the day of human chorionic gonadotropin administration. There was no difference in the number of retrieved oocytes, but the antagonist group had a higher proportion of mature oocytes, 82% +/- 4% versus 62.4% (p = 0.02), and a higher proportion of embryos of good quality, 69.8% +/- 9.8% versus 44.3% +/- 7.2% (p = 0.03) in the agonist group. Granulosa-lutein cells from antagonist-treated women showed significantly lower aromatase activity the first 6 hours after retrieval, 17.6 +/- 1.6 versus 31.3 +/- 7.4 ng/ml per 6 hours estradiol (p = 0.03), whereas basal and gonadotropin-stimulated with progesterone responses were similar. CONCLUSION: Gonadotropin-releasing hormone antagonist administration during the late follicular phase resulted in lower serum luteinizing hormone and estradiol levels and more mature oocytes and embryos of better quality compared with gonadotropin-releasing hormone agonist administration. These results suggest that gonadotropin-releasing hormone antagonist administration in ovarian hyperstimulation has practical advantages over the agonist regimen. Gonadotropin-releasing hormone analogs may have direct action on ovarian function with differential effects on granulosa-lutein cell aromatase activity. This could explain the lower serum estradiol levels routinely observed in women given gonadotropin-releasing hormone antagonist.

Gonadotropin-releasing hormone receptor gene expression in human ovary and granulosa-lutein cells.

GnRH regulates gonadotropin biosynthesis and release in the anterior pituitary via specific receptors. Although extrapituitary expression and action of GnRH have been shown in some species, in the human it is not clear whether GnRH has a peripheral action. In this study we sought to determine whether the human ovary expresses GnRH receptor (GnRHR) messenger ribonucleic acid (mRNA). Ovarian tissues from 11 women (32-61 yr old) and granulosa-lutein (GL) cells purified from follicular aspirates of 51 women undergoing oocyte retrieval for in vitro fertilization were analyzed by ribonuclease protection assay and reverse transcriptase-polymerase chain reaction (RT-PCR). Human pituitaries, lymphocytes, and placenta were also studied. Measurable levels of GnRHR mRNA were found by ribonuclease protection assay in 2 of 10 ovaries, in 2 of 4 GL cells preparations from women whose ovarian hyperstimulation involved a GnRH agonist, in GL cells from 3 women whose ovarian hyperstimulation involved a GnRH antagonist, and in human pituitaries. Relative to the total amount of RNA analyzed, the level of GnRHR mRNA was about 200-fold lower in the ovary than in the pituitary. A sequence of 314 basepairs of GnRHR mRNA was amplified by RT-PCR in the pituitary, in 9 of 10 ovaries, and in 4 of 5 GL cell preparations. No message could be amplified in human lymphocytes, and placental specimens showed a weak signal. The relative GnRHR mRNA levels in GL cells from 13 women analyzed by quantitative RT-PCR showed a wide range of individual differences. These results suggest that GnRHR mRNA is expressed in GL cells and the human ovary across different functional stages, implying that multiple ovarian compartments may express GnRH receptors. The administration of GnRH analogs may have a further direct action on the human ovary.

Gonadotroph adenoma in a premenopausal woman secreting follicle-stimulating hormone and causing ovarian hyperstimulation.

The clinical manifestations of gonadotroph adenomas are almost always neurological, consequences of their large size, and are rarely endocrinological. We report an exception, a 39-yr-old woman whose gonadotroph adenoma caused supranormal serum concentrations of FSH, which resulted in the development of multiple ovarian cysts, persistent elevation of her serum estradiol concentration, and endometrial hyperplasia. She initially presented because of amenorrhea at age 30 yr and was treated for an intrasellar mass by transsphenoidal surgery at age 31 yr and again at age 36 yr. Before and after the second operation she had persistently supranormal plasma estradiol concentrations (> 1840 pmol/L) and endometrial hyperplasia. When she was evaluated at age 39 yr, transvaginal ultrasound showed multiple ovarian cysts and endometrial thickening. Her plasma estradiol level was markedly supranormal (2160 pmol/L), FSH was mildly supranormal (17.8 IU/L), and alpha-subunit was markedly supranormal (23.3 micrograms/L). Characteristic of gonadotroph adenomas, her LH beta level increased by 69% in response to TRH. Neither FSH nor alpha-subunit decreased in response to administration of the GnRH antagonist, Nal-Glu-GnRH (5 mg/12 h for 4 weeks). Excised adenoma tissue exhibited morphological features of a gonadotroph adenoma. This patient appears to be unique, in that her gonadotroph adenoma caused slightly, but persistently, supranormal concentrations of FSH, which caused ovarian stimulation, including supranormal plasma estradiol concentrations, multiple ovarian cysts, and endometrial hyperplasia. We propose that gonadotroph adenomas be considered in the differential diagnosis of patients who have this constellation of abnormalities.

Microbial predation in coupled chemostats: a global study of two coupled nonlinear oscillators.

Predator-prey systems in continuously operated chemostats exhibit sustained oscillations over a wide range of operating conditions. When two such chemostats interact through flow exchange, the interplay of the oscillation frequencies gives rise to a wealth of dynamic behavior patterns. Using numerical bifurcation techniques, we perform a detailed computational study of these patterns and the transitions between them as the coupling strength and relative frequencies of the two chemostats vary. We concentrate on certain strong resonance phenomena between the two frequencies as well as their mutual extinction and provide a representative sampling of possible phase portraits for our model system. Our observations corroborate recent mathematical results and case studies of coupled nonlinear chemical oscillators in which regions of mutual extinction as well as the Arnol'd structure for two-parameter families of maps of the plane have been observed. We highlight certain unexpected features of the operating diagram discovered through our computational study and discuss their implication for the dynamic response of the chemostat system.

Gonadotropin-releasing hormone-dependent chorionic gonadotropin secretion in a menopausal woman.

We report the evaluation of a 46-yr-old asymptomatic menopausal woman whose serum hCG concentrations remained persistently supra-normal for 3 yr (mean +/- SD, 20 +/- 10 IU/L; n = 19). Holo-hCG and beta-core fragments were detected in the patient's urine by Ultragel chromatography, followed by specific RIAs. Trophoblastic, germ cell, and other malignancies appeared to be excluded by the absence of serum tumor markers and imaging procedures of the pelvis, abdomen, breast, and chest. Administration of a single bolus dose of synthetic GnRH (100 micrograms) increased the serum hCG concentration by 50% (from 26 to 40 IU/L). Administration of the Nal-Glu GnRH antagonist (5 mg, sc, every 12 h for 1 week) decreased the serum hCG concentration from 27 to 4.6 IU/L. The pronounced decrease in the serum hCG concentration during antagonism of the action of endogenous GnRH by administration of Nal-Glu GnRH suggests that the pituitary is the source of the supra-normal serum hCG concentrations, because the pituitary is exposed to the highest concentration of endogenous GnRH.