Semisynthesis of new sulfated heterorhamnan derivatives obtained from green seaweed Gayralia brasiliensis and evaluation of their anticoagulant activity

Marine green algae produce sulfated polysaccharides with diverse structures and a wide range of biological activities. This study aimed to enhance the biotechnological potential of sulfated heterorhamnan (Gb1) from Gayralia brasiliensis by chemically modifying it for improved or new biological functions. Using controlled Smith Degradation (GBS) and O-alkylation with 3-chloropropylamine, we synthesized partially water-soluble amine derivatives. GBS modification increase sulfate groups (29.3 to 37.5 %) and α-l-rhamnose units (69.9 to 81.2 mol%), reducing xylose and glucose, compared to Gb1. The backbone featured predominantly 3- and 2-linked α-l-rhamnosyl and 2,3- linked α-l-rhamnosyl units as branching points. Infrared and NMR analyses confirmed the substitution of hydroxyl groups with aminoalkyl groups. The modified compounds, GBS-AHCs and GBS-AHK, exhibited altered anticoagulant properties. GBS-AHCs showed reduced effectiveness in the APTT assay, while GBS-AHK maintained a similar anticoagulant activity level to Gb1 and GBS. Increased nitrogen content and N-alkylation in GBS-AHCs compared to GBS-AHK may explain their structural differences. The chemical modification proposed did not enhance its anticoagulant activity, possibly due to the introduction of amino groups and a positive charge to the polymer. This characteristic presents new opportunities for investigating the potential of these polysaccharides in various biological applications, such as antimicrobial and antitumoral activities.

Semisynthesis and characterization of versatile azide intermediates using sodium alginate and its homopolymeric derivatives as starting material

Alginate, a polyuronic biopolymer composed of mannuronic and guluronic acid units, contain hydroxyl and carboxyl groups as targeting modification sites to obtain structures with new and/or improved biological properties. The copper-catalyzed azide-alkyne cycloaddition (CuAAC) is a versatile click reaction for polymer functionalization, but it typically requires a "pre-click" modification to introduce azide or alkyne groups. Here, we described a straightforward chemical path to selectively modify alginate carboxyl groups producing versatile azido derivatives through N-acylation using 3-azydopropylamine. The resulting azide-functionalized polysaccharides underwent click chemistry to yield amino derivatives, confirmed by NMR and FTIR analyses. The 1H NMR spectrum reveals a characteristic triazole group signal at 8.15 ppm. The absence of the azide FTIR band for all amino derivatives, previously observed for the N-acylation products, indicated reaction success. Antibacterial and antioxidant assessments revealed that the initial polysaccharide lacks E. coli inhibition, while the click chemistry-derived amine products exhibit growth inhibition at 5.0 mg/mL. Lower molecular weight derivatives demonstrate superior DPPH scavenging ability, particularly amino-derivatives (24-33 % at 1.2 mg/mL). This innovative chemical pathway offers a promising strategy for developing polysaccharide structures with enhanced properties, demonstrating potential applications in various fields.

Pharmacokinetics of oral ciprofloxacin in adult patients: A scoping review

AIMS

To map the literature on oral ciprofloxacin's pharmacokinetics and its implications for dose adjustments in specific populations.

METHODS

A scoping review was performed according to the Cochrane Collaboration and JBI and reported following the PRISMA-ScR. Systematic searches on electronic databases were conducted to integrate the current evidence on ciprofloxacin's pharmacokinetics. The quality of the included studies was assessed using ClinPK's checklist.

RESULTS

The search yielded 55 relevant studies. Within the traditional pharmacokinetics studies (n = 46), 86 profiles were examined (72 involving healthy patients and 14 with various clinical conditions). Oral ciprofloxacin's pharmacokinetics were influenced by covariates such as drug interactions (ferrous ions, calcium carbonate, diclofenac and itraconazole), food interactions (calcium-rich foods), elderly populations and renal impairment. Notably, variability in pharmacokinetic parameters existed among subjects, regardless of their health status, underscoring the need for comprehensive population descriptions. Population pharmacokinetic studies (n = 9) identified significant covariates for hospitalized patients, such as creatinine clearance, plasma bicarbonate, estimated glomerular filtration rate, renal replacement therapy, age, sex, total bilirubin, fat-free mass, dietary factors in renal disease, rifampicin for clearance models and body weight for volume of distribution models. Most pharmacokinetic/pharmacodynamic assessments concluded that 1200 mg/day provides a high probability of target attainment for bacteria with minimum inhibitory concentration <0.5 mg L-1 , aiming for an area under the curve for 24 h/minimum inhibitory concentration >125 h.

CONCLUSIONS

This study offers a comprehensive overview regarding oral ciprofloxacin's pharmacokinetics across various health conditions. It highlights the complexities of ciprofloxacin's pharmacokinetics, emphasizing the importance of considering multiple factors in dose adjustments.

P-077 Human sperm acrosome becomes alkalinized during capacitation

Study question

Does during the human sperm capacitation the acrosomal pH (pHa) increases naturally and how it change can be modulate?

Summary answer

Sperm acrosome is progressively alkalinized during capacitation in a HCO3- and Ca2+ dependent manner. pHa is regulated by V-ATPase and involving the sAC-PKA signaling pathway.

What is known already

Capacitation involves biochemical and physiological modifications undergone by sperm as they travel through the female reproductive tract. These modifications prepare the sperm to enact the acrosome reaction (AR), an essential step for egg fertilization. Capacitation requires [Ca2+]i and pHi increases. Mouse sperm capacitation is accompanied by acrosomal alkalinization and artificial elevation of the pHa is sufficient to trigger the AR in mouse and human sperm, but it is unknown if the pHa increases physiologically during human sperm capacitation.

Study design, size, duration

In this work we followed pHa changes during human sperm capacitation (6 h) and evaluated the mechanisms of its regulation using pharmacological tools. Sperm were stained with LysoSensor green and the relative fluorescence measurements for pHa kinetics during capacitation were performed at 15 min of incubation (initial time: 0 h) and after 3 and 6 h of incubation. Independent experiments of at least 3 donors were performed per condition.

Participants/materials, setting, methods

We used semen samples from 11 healthy donors fulfilled the requirements defined by the OMS (OMS, 2010). Sperm recovered by swim-up were incubated in a capacitating or non-capacitating HTF medium. LysoSensor green fluorescence dye was used to evaluate pHa dynamic during capacitation using single cell epifluorescence microscopy and image-based flow cytometry. Additionally, pHa was evaluated in the presence of specific inhibitors to assess regulatory mechanisms. A linear model was used to study the pHa kinetics.

Main results and the role of chance

Human sperm pHa is alkalinized progressively at 3 and 6 h of the capacitation (p &lt; 0.05).

V-ATPase activity mainly responsible for the acrosome acidity and can modulate at least in part acrosome alkalinization during capacitation (***p&lt;0.001, *p&lt;0.05). V-ATPase is immunolocalized to the acrosome and equatorial segment of human sperm.

Bicarbonate (HCO3-) was essential for the pHa increase observed during capacitation and its absence inhibits completely the acrosome alkalinization (**p&lt;0.01, *p&lt;0.05). Inhibition of the Cystic Fibrosis Transmembrane Regulator (CFTR) or the Na+/HCO3- Cotransporter (NBC) partially blocked the pHa changes during capacitation.

Extracelular Ca2+ is involved in pHa regulation during capacitation. Under low external Ca2+ the pHa regulation is altered and occurred delay in acrosome alkalinization (*p &lt; 0.05 and **p &lt; 0.001).

Finally, we tested a pharmacological blockade of sAC and PKA during capacitation. sAC inhibition did not prevent acrosome alkalinization, but it significantly reduced the rate of the pHa changes as compared to the capacitation control (***p=0.0009), revealing a certain influence. On the other hand, PKA inhibition induced acrosomal acidification at the start of capacitation and accelerated significantly the alkalinization (*p&lt;0.05). Together these results allow us to assume that a signaling pathway mediated to sAC is participating in the pHa regulation.

Limitations, reasons for caution

Experiments were performed in vitro and due to model limitations is difficult to establish strategies that allow us to know more directly, other molecular mechanisms that regulate the pHa.

Wider implications of the findings

Our findings show that pHa is subject of regulation during human sperm capacitation. The results provide new insights regarding the molecular mechanisms involved in human sperm capacitation and this knowledge results interesting for the study of specific molecules that inhibit capacitation or AR.

Trial registration number

Not applicable

Morphological study of electrospun chitosan/poly(vinyl alcohol)/glycerol nanofibres for skin care applications

This study aimed to evaluate the influence of formulation and procedure parameters in obtaining thick and continuous chitosan/PVA/glycerol nanofibres to be applied in skin care. For that, the polymers were characterized by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and size-exclusion chromatography. After this, 96 chitosan/PVA/glycerol nanofibre scaffolds were prepared by electrospinning method, using factorial designs. The independent variables were crude and pure chitosan, 2 brands of PVA, 2 needle gauges, high and low polymer concentration, high and low glycerol concentration, and final solution with and without ultrafiltration. Morphological analysis was performed by scanning electron microscopy, atomic force microscopy, and confocal microscopy. The best sample (NF67) presented an average thickness of 268.3 nm, uniform distribution, and high yield. It was obtained at a 1:3.5 (crude chitosan: PVA with lower molecular weight, but more hydrolysed) ratio and lower glycerol concentration, suggesting that the degree of hydrolysis of the PVA is more important than its molecular weight for obtaining better quality nanofibres and that the glycerol also makes the electrospinning process difficult. Thus, it was possible to choose parameters that provide scaffolds that could be applied as a matrix extracellular-like material in wound healing.

Assessing the effects of PMM2 variants on protein stability

Phosphomannomutase 2 deficiency, PMM2-CDG, is the most frequent disorder of protein N-glycosylation. It is an autosomal recessive disease with a broad clinical and biochemical phenotype. Trying to predict the impact of novel variants is often a challenge due to the high number of variants and the difficulty to establish solid genotype-phenotype correlations. A potential useful strategy is to use computational chemistry calculations as a tool from which relevant information on the structural impact of novel variants may be deduced. Here we present our analyses based on four well-known PMM2 deleterious variants (p.(Leu32Arg), p.(Asp65Tyr), p.(Phe119Leu), p.(Arg141His)) and the polymorphic p.(Glu197Ala) for which we have predicted the effect on protein stability. Our work predicts the effect of different amino acid residues on the conformation and stability of PMM2. These computational simulations are, therefore, an extremely useful methodology which, in combination with routinely used in silico methods of pathogenicity prediction, may help to reveal the structural impact of novel variants at the protein level, potentially leading to a better understanding of target biological molecules.

Advances in microalgal cell wall polysaccharides: a review focused on structure, production, and biological application

Microalgae have been shown to be useful in several biotechnological fields due to their feasible cultivation and high-value biomolecules production. Several substances of interest produced by microalgae, such as: proteins, lipids, and natural colorants, have already been explored. Based on the continuing demand for new natural molecules, microalgae could also be a valuable source of polysaccharides. Polysaccharides are extremely important in aquaculture, cosmetics, pharmaceutical, and food industries, and have great economic impact worldwide. Despite this, reviews on microalgal polysaccharide production, biological activity, and chemical structure are not abundant. Moreover, techniques of microalgal cultivation, coupled with carbohydrate production, need to be clarified in order to develop forward-looking technologies. The present review provides an overview of the main advances in microalgal cell wall polysaccharide production, as well as their associated potential biological applications and chemical structure. Several studies on future prospects, related to microalgae are presented, highlighting the key challenges in microalgal polysaccharide production.

A microparticle blood analogue suspension matching blood rheology

The handling of blood in vitro is demanding because of ethical, economical and safety issues. Although several Newtonian and non-Newtonian blood analogues are found in the literature, few studies have used particles to mimic red blood cells (RBCs) and built an analogue with similar rheological properties of blood. This work reports the development of a blood analogue suspension composed of polydimethylsiloxane (PDMS) microparticles with an average diameter of ∼7 μm. High throughput production of PDMS particles is possible using a multi-stage membrane emulsification process; up to ∼6 mL of microparticles are manufactured in 3 hours. PDMS particles at a concentration of around 21% (w/w) at 20 °C present steady, oscillatory and extensional rheologies very similar to those of blood under physiological conditions (37 °C and ∼41% hematocrit), making them a good candidate whole blood analogue. Also, flow studies were performed in microchannels with contraction to study the cell-free layer (CFL) formation and particle deformation, achieving good qualitative results. Using the procedure developed, it is possible to obtain blood analogue fluids with a shelf life of at least 6 months.

Experimental Multidisciplinary Approach Based on Compounded Capsule's Quality Evaluation for Pharmacy Undergraduate Courses

Active learning is common in pharmacy school. However, such learning strategy rarely integrates more than one specific field. Here, we develop a new active multidisciplinary approach centered on compounded capsule's quality evaluation. Captopril capsules were chosen for their important role to control systemic arterial hypertension, a highly prevalent disease. The study design was developed and demonstrated by two undergraduate students. Four compounding pharmacies were selected randomly, and sixty capsules of captopril 25 mg were purchased from each pharmacy at three different periods (12 batches). The capsules were evaluated according to general aspects (visual observation), label information (according to the Brazilian Pharmacopoeia's regulation), weight variation (standard method), and uniformity of dosage units (iodine titration). All batches met the requirements expected for general aspects and one pharmacy did not meet minimum label criteria. Weight variation out of the standard limits was observed for three of the batches evaluated, and five batches were found to be out of the acceptable captopril's dosage. All stages of this activity resulted in important discussions pertaining to the education of pharmacists. The experimental multidisciplinary approach presented a lead to different discussions on several expertise fields and might have a great impact on the formation of future pharmacist. Several topics could be addressed using this activity, such as analytical chemistry, titration, stoichiometry, medicine preparation, pharmacological risks, et h i c a l aspects, and the pharmacist's role to guarantee health.

Development and Evaluation of an Anti-aging Cosmetic Formulation Exploring Antioxidant Potential of Vitis vinifera L

An important skin aging mechanism is oxidative stress. Reactive oxygen species in excess leads to skin integrity loss and visible changes. Antioxidants are able to prevent reactive oxygen species damage, making their supplementation important to slow down the aging process. We evaluated Vitis vinifera L. extract antioxidant potential to be applied for cosmetic purpose. The sample's thin-layer chromatography profile and antioxidant results indicated a good antioxidant activity. The extract was incorporated into different formulations, and a stability study was conducted with the emulsion chosen. Organoleptic and physicochemical parameters were evaluated, as well as the microbial count. The formulation was found to be in compliance with current standards and has the potential to be further studied and used as an anti-aging cosmetic.

Effectiveness of treat-and-extend versus pro re nata regimens in the treatment of Neovascular Age Macular Degeneration: A Real World Comparison

PURPOSE

Evaluate and compare the visual and morphological results of Pro re nata (PRN) and treat-and-extend (T&E) treatment regimens at 3 years in real world clinical practice.

METHODS

Retrospective study of patients with neovascular age macular degeneration (AMD) treated with anti-VEGF with 3 years of continuous follow-up and no previous anti-VEGF treatment. Best corrected visual acuity (BCVA), central foveal thickness (CFT) and number of intravitreal injections outcomes were tested for statistical differences between the two groups at baseline and during follow-up.

RESULTS

A total of 240 eyes were included in the study, 170 in the PRN group and 70 in the T&E group. At 12 months, mean BCVA (ETDRS letters) gain from baseline was at its highest point in the T&E group (+6.38±13.32; p=0.25). In the PRN group, BCVA peaked at 3 months and slowly decreased until end of follow-up. With both regimens, from baseline, CFT continued to decrease until the second year (PRN -138.81 [-846.7 to +162.77] and T&E -81 [-604 to +100] μm, p=0.06). After that, T&E group maintained this tendency, reaching the lowest CFT value at 36 months, whereas PRN group showed an increased in CFT values (PRN -104 [-807.7 to +297] μm and T&E -103 [-575 to +244], μm p=0.63). Patients treated with T&E regimen received a significantly higher number of injections (PRN 16.3±7.6 vs T&E 23.9 ±9.4, p<0.01).

CONCLUSION

Our results demonstrated a trend towards for T&E to achieve higher marks in BCVA, peaking at 12 months, and lower CFT thickness at the end of three years. Despite the higher number of injections performed in the T&E group the mean BCVA reverts to baseline values at 3 years.

Evaluation of the application of the Diabetes Quality of Life Questionnaire in patients with diabetes mellitus

Objective Diabetes mellitus (DM) is a chronic disease with great impact on patients' quality of life (QoL). This variable can be measured using reliable, standardized, and validated instruments. The purpose of this study was to evaluate the application and reporting of the Diabetes Quality of Life Measure (DQOL) or the Diabetes Quality of Life for Youths Measure (DQOLY), an adapted version for young patients with DM. Materials and methods A systematic review of interventional and observational studies using the DQOL or DQOLY was performed. Searches were conducted in the electronic databases Medline, Scopus, Web of Science, Lilacs, and SciELO. Results After conducting the searches, 111 studies met the inclusion criteria and were included in the qualitative analysis. Of these, 32 studies were classified as interventional and 79 as observational, with 27,481 patients. The DQOL was applied in 82 studies, the DQOLY in another 27, and two studies used both instruments. DM was classified as type 1 DM in 69 studies and type 2 DM in 35 studies. Six studies included both patients. Improvement in patients' QoL after an intervention was observed in 13 interventional studies. Most of the studies (90%) provide a detailed description of the instrument and 52% the previous validation. The interpretation of the scores obtained varies among the studies, probably due to the differences inherent in cultural validations, translations, and adaptations. Conclusion The application of the instruments in clinical practice must be rigorously standardized and requires an accurate understanding of psychometric and statistical concepts. Arch Endocrinol Metab. 2020;64(1):59-65.

Chemical structure and snake antivenom properties of sulfated agarans obtained from Laurencia dendroidea (Ceramiales, Rhodophyta)

Aqueous and KCl-soluble polysaccharides were extracted from Laurencia dendroidea (Rhodomelaceae, Ceramiales) and their chemical profile was accessed by anion-exchange chromatography, chemical and spectroscopic analyses. The homogeneous agaran DHS-4 (181.3 × 10³ g. mol^-1, 21.3% of NaSO₃) presents A units mostly 2-sulfated (18.9 mol%), nonsubstituted (15.3 mol%) and 6-O-methylated (10.1 mol%), while B units are l-sugars composed predominantly by galactose 6-sulfate precursor units (19.2 mol%) and 3,6-anhydrogalactose (13.8 mol%), besides non-precursor galactose 6-sulfate units bearing d-xylose substituents on C-3 (8.1 mol%). The crude KCl-soluble DHS agaran (20.5% of NaSO₃) inhibited proteolysis and hemolysis induced by Lachesis muta and Bothrops jararaca venoms. DHS was able to inhibit up to 75% the L. muta venom hemorrhagic effect and to reduce the lethality displayed by B. jararaca venom, increasing the mice survival time up to 3 times. Therefore, this agaran has high potential to be used as an additional tool to treat snakebite envenomation.

Synthesis of ceramic pigments from industrial wastes: Red mud and electroplating sludge

The perception of industrial waste has changed, in the last decades, from an economic and environmental problem to a potential raw material. In this work, the synthesis of a stable pigment was prepared by combining two hazardous and unexplored wastes: red mud (RM, rich in Fe) and electroplating sludge (ES, rich in Ni/Cr). The wastes were mixed in different proportions and calcined at 1200 °C. Black and brown pigments were obtained from the mixture of RM/ES in 1:3 and 1:1 wt proportions, respectively. The color was given by the chrome-iron-nickel spinels, based on Ni^{2+ 3}T_1g(³F) transitions (≈13,000 cm^-1), Cr^{3+ 4}A_2g → ⁴T_1g(⁴F) transitions (≈24,400 cm^-1) and Fe³⁺ (≈15,000-≈22,500 cm^-1). The achieved coloring strength and thermal stability on various ceramic glazes render excellent prospects for the industrial application of such waste-based pigments.

Synthesis and in vitro PDT evaluation of new porphyrins containing meso-epoxymethylaryl cationic groups

OBJECTIVES

Photodynamic therapy (PDT) is an effective cancer treatment that uses photosensitizers, light, and oxygen to destroy malignant cells. Porphyrins, and in particular the cationic derivatives, are the most investigated photosensitizers for PDT. In this context, it is important to study new methodologies to develop efficient cationic photosensitizers for use in PDT.

MATERIALS AND METHODS

New porphyrins bearing cationic epoxymethylaryl groups were synthesized and characterized. Their cellular uptake, intracellular localization, and phototoxicity were evaluated in human HEp2 cells, and compared with their methylated analogs.

RESULTS

All cationic porphyrins were efficient generators of singlet oxygen, with quantum yields in the range 0.35-0.61. The two methylated derivatives (3 and 4) accumulated the most within cells at all times investigated, up to 24 hours. Of these two porphyrins, 4 was the most phototoxic to the cells (LD₅₀  = 2.4 μM at 1.5 J/cm² ); however, porphyrin 3 also showed high phototoxicity (LD₅₀  = 7.4 μM at 1.5 J/cm² ). The epoxymethyl-containing porphyrins were found to be less phototoxic than the methylated derivatives, with LD₅₀ > 38 μM. The neutral porphyrins showed no phototoxicity up to the 100 μM concentrations investigated, and had the lowest singlet oxygen quantum yields. All cationic porphyrins localized mainly in the cell ER, Golgi apparatus, and lysosomes.

CONCLUSION

Our results suggest that cationic methylated porphyrin derivatives are promising PDT photosensitizing agents. The epoxymethyl-containing derivatives showed increased efficacy relative to the neutral analogs, and are good candidates for further investigation. Lasers Surg. Med. 50:566-575, 2018. © 2018 Wiley Periodicals, Inc.

Reactive pulsed-DC sputtered Nb-doped VO2 coatings for smart thermochromic windows with active solar control

Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive pulsed-DC magnetron sputtering. Different Nb doping amounts were introduced in the VO2 solid solution during the film growing which resulted in films with distinct semiconducting-metal phase transition temperatures. Pure VO2 showed improved thermochromic behavior as compared with VO2 films prepared by conventional DC sputtering. The transition temperatures were linearly decreased from 59 down to 34 degrees C with the increase in Nb content. However, the luminous transmittance and the infrared modulation efficiency were markedly affected. The surface morphology of the films was examined by scanning electron microscopy (SEM) and showed a tendency for grain sized reduction due to Nb addition. Moreover, the films were found to be very dense with no columnar microstructure. Structural analyses carried out by X-ray diffractometry (XRD) revealed that Nb introduces significant amount of defects in the crystal lattice which clearly degrade the optical properties.

Mitochondrial lineages reveal intense gene flow between Iberian wild boars and South Iberian pig breeds

The phylogeography of wild boars (WB) and domestic pigs (Sus scrofa) has contributed important insights into where and when domestication occurred. The geographic distribution of two core haplotypes (E1a and E1c) of the main European phylogenetic clade suggests that Central Europe was an early domestication centre, although the complexity of the pattern does not exclude the possibility that multiple domestication events occurred in different regions. To investigate the relationships among WB and domestic pig breeds in Iberia, a fragment of the mitochondrial DNA control region from a large sample (n=409) of WB and local pig breeds was co-analysed with published sequences from other European populations. The Iberian sample revealed a high frequency of a sub-cluster (E1c) of the European haplogroup E1 in 77% of total Iberian samples, 96% of WB, 90% of Alentejano (Portugal) and 87% of Iberian breed pigs (Spain; Black Hairy, Black Hairless and Red varieties). Low genetic distance (F'(ST) = 0.105) was observed between Alentejano (Portugal) and Iberian breed pigs (Spain). Alentejano and Iberian breed pigs showed low genetic distances to both Iberian and Central European WB (average F'(ST) =0.345 and 0.215, respectively). This pattern suggests that early pig husbandry in the Iberian Peninsula did not solely rely on imported Central European stock, but also included the recruitment of local WB.

Nanocomposite metal amorphous-carbon thin films deposited by hybrid PVD and PECVD technique

Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving adhesion and compatibility with substrates. In this work new nanocomposite coatings with improved toughness based in nanocrystalline phases of metals and ceramics embedded in amorphous carbon matrix are being developed within the frame of a research project: nc-MeNxCy/a-C(Me) with Me = Mo, Si, Al, Ti, etc. Carbide forming metal/carbon (Me/C) composite films with Me = Mo, W or Ti possess appropriate properties to overcome the limitation of pure DLC films. These novel coating architectures will be adopted with the objective to decrease residual stress, improve adherence and fracture toughness, obtain low friction coefficient and high wear-resistance. Nanocomposite DLC's films were deposited by hybrid technique using a PVD-Physically Vapor Deposition (magnetron sputtering) and Plasma Enhanced Chemical Vapor Deposition (PECVD), by the use of CH4 gas. The parameters varied were: deposition time, substrate temperature (180 degrees C) and dopant (Si + Mo) of the amorphous carbon matrix. All the depositions were made on silicon wafers and steel substrates precoated with a silicon inter-layer. The characterisation of the film's physico-mechanical properties will be presented in order to understand the influence of the deposition parameters and metal content used within the a-C matrix in the thin film properties. Film microstructure and film hybridization state was characterized by Raman Spectroscopy. In order to characterize morphology SEM and AFM will be used. Film composition was measured by Energy-Dispersive X-ray analysis (EDS) and by X-ray photoelectron spectroscopy (XPS). The contact angle for the produced DLC's on silicon substrates were also measured. Thin film adherence was studied by micro-scratch test. Residual stresses in the produced coatings will be analysed by bending technique.

DC sputtered W-doped VO2 thermochromic thin films for smart windows with active solar control

Doped VO2 thin films, with different W at.% and consequent dissimilar transition temperatures, were successfully deposited onto SiO2-coated float-glass substrates by reactive direct current (DC) magnetron sputtering. Structural analyses have shown, for undoped films, single phase VO2(M) films with c-axis (002) direction as the preferred crystal orientation. The addition of tungsten into the VO2 solid solution favored the crystallization in the (011) direction which became dominant above a critical level of dopant concentration. The surface morphology of pure VO2 films revealed elongated grains oriented within the film plane. The doped films evidenced an increased tendency to be oriented out of the film plane which has resulted in increased roughness levels. The doping methodology associated with optimized processing conditions allowed the production of W-doped VO2 films with reduced transition temperatures, from 63 down to 28 degrees C, and maximum transmittances at the visible region ranging 40%. The relationship between tungsten content in the film and consequent transition temperature expressed a linear behavior.

Allelic penetrance approach as a tool to model two-locus interaction in complex binary traits

Many binary phenotypes do not follow a classical Mendelian inheritance pattern. Interaction between genetic and environmental factors is thought to contribute to the incomplete penetrance phenomena often observed in these complex binary traits. Several two-locus models for penetrance have been proposed to aid the genetic dissection of binary traits. Such models assume linear genetic effects of both loci in different mathematical scales of penetrance, resembling the analytical framework of quantitative traits. However, changes in phenotypic scale are difficult to envisage in binary traits and limited genetic interpretation is extractable from current modeling of penetrance. To overcome this limitation, we derived an allelic penetrance approach that attributes incomplete penetrance to the stochastic expression of the alleles controlling the phenotype, the genetic background and environmental factors. We applied this approach to formulate dominance and recessiveness in a single diallelic locus and to model different genetic mechanisms for the joint action of two diallelic loci. We fit the models to data on the genetic susceptibility of mice following infections with Listeria monocytogenes and Plasmodium berghei. These models gain in genetic interpretation, because they specify the alleles that are responsible for the genetic (inter)action and their genetic nature (dominant or recessive), and predict genotypic combinations determining the phenotype. Further, we show via computer simulations that the proposed models produce penetrance patterns not captured by traditional two-locus models. This approach provides a new analysis framework for dissecting mechanisms of interlocus joint action in binary traits using genetic crosses.

[An outbreak of acute schistosomiasis at Porto de Galinhas beach, Pernambuco, Brazil]

We recently confirmed several cases of acute schistosomiasis in Porto de Galinhas beach, Northeast Brazil. A total of 662 patients were diagnosed by parasitological and clinical examinations. The infection likely occurred during the September 7 national holiday, when heavy rainfall flooded the Ipojuca River and people were infected when the water covered their yards. Families were continuously exposed to infection for a period of three weeks until the water had completely dried up. Previous investigation suggests that snail vectors were introduced as a result of landfill in marshy areas. The swamp-flooding of such areas facilitated the emergence of slums surrounded by snail breeding sites. Heavy rainfall caused open-air sewage ditches to overflow, allowing for infection of snails by Schistosoma mansoni. Thus, continuous floods were responsible for the spread of human infection. Clinical and laboratory results identified 62% of acute cases of S. mansoni. Complementary studies are being conducted to define the impact and epidemiological meaning of the acute schistosomiasis outbreak.

Three-cell interactions in T cell-mediated suppression? A mathematical analysis of its quantitative implications

Aiming to further our understanding of T cell-mediated suppression, we investigate the plausibility of the hypothesis that regulatory T cells suppress other T cells (target cells), while both cells are conjugated with one APC. We use a mathematical model to analyze the proliferation inhibition scored during in vitro suppression assays. This model is a radical simplification of cell culture reality, assuming that thymidine incorporation is proportional to the number of target cells that would instantaneously form conjugates with APCs that are free of regulatory cells. According to this model the inhibition index should be mainly determined by the number of regulatory cells per APC and should be insensitive to the number of target cells. We reanalyzed several published data sets, confirming this expectation. Furthermore, we demonstrate that the instantaneous inhibition index has an absolute limit as a function of the number of regulatory cells per APC. By calculating this limit we find that the model can explain the data under two non-mutually exclusive conditions. First, only approximately 15% of APCs used in the suppression assays form conjugates with T cells. Second, the growth of the regulatory cell population depends on the target cells, such that the number of regulatory cells per APC increases when they are cocultured with target cells and overcomes its limit. However, if neither of these testable conditions is fulfilled, then one could conclude that suppression in vitro does not require the formation of multicellular conjugates.

Modelling T-cell-mediated suppression dependent on interactions in multicellular conjugates

Tolerance to peripheral body antigens involves multiple mechanisms, namely T-cell-mediated suppression of potentially autoimmune cells. Recent in vivo and in vitro evidence indicates that regulatory T cells suppress the response of effector T cells by a mechanism that requires the simultaneous conjugation of regulatory and effector T cells with the same antigen-presenting cell (APC). Despite this strong requirement, it is not yet clear what happens while both cells are conjugated. Several hypotheses are discussed in the literature. Suppression may result from simple competition of regulatory and effector cells for activation resources on the APC; regulatory T cells may deliver an inhibitory signal to effector T cells in the same conjugate; or effector T cells may acquire the regulatory phenotype during their interaction with regulatory T cells. The present article tries to further our understanding of T-cell-mediated suppression, and to narrow-down the number of candidate mechanisms. We propose the first general formalism describing the formation of multicellular conjugates of T cells and APCs. Using this formalism we derive three particular models, representing alternative mechanisms of T-cell-mediated suppression. For each model, we make phase plane and bifurcation analysis, and identify their pros and cons in terms of the relationship with the large body of experimental observations on T-cell-mediated suppression. We argue that accounting for the quantitative details of adoptive transfers of tolerance requires models with bistable regimes in which either regulatory cells or effectors cells dominate the steady state. From this analysis, we conclude that the most plausible mechanism of T-cell-mediated suppression requires that regulatory T cells actively inhibit the growth of effector T cells, and that the maintenance of the population of regulatory T cells is dependent on the effector T cells. The regulatory T cell population may depend on a growth factor produced by effector T cells and/or on a continuous differentiation of effector cells to the regulatory phenotype.

A mathematical analysis of TCR serial triggering and down-regulation

Despite the increasing knowledge on the pathways involved in TCR signal transduction and T cell activation, the molecular mechanism of TCR triggering by ligand, MHC-peptide complexes, is still elusive and controversial. The present paper addresses the controversy on the early events of TCR engagement and triggering. Mathematical modelling techniques are applied to experimental data to infer plausible molecular mechanisms of TCR triggering and down-regulation. A similar approach has been followed by Bachmann et al. (Eur. J. Immunol. 1998, 28: 2571 - 2579), who concluded that the TCR triggering requires the formation of MHC-TCR dimers or trimers. We report here the failure to generalize this conclusion to the data reported by Valitutti et al. (Nature 1995, 375: 148 - 151). We show that there are several kinetic features in these experimental curves of TCR down-regulation that cannot be explained by the simple model proposed by Bachmann et al. unless some phenomenological extensions are considered. These extensions are: (1) a ligand independent turnover of the TCR; (2) a transient accumulation of triggered TCR; (3) a high order of TCR triggering kinetics; and (4) two pools of membrane TCR in dynamic equilibrium.

Functional diversity of natural IgM

This paper proposes a method for the quantitative characterization of repertoire diversity of an unknown mixture of antibodies on the basis of its reactivity profile in the quantitative immunoblot (QIB). The QIB is calibrated by measuring the reactivity profiles of supernatants of known 'diversity' (i.e. known numbers of B cell clones). We define a quantitative 'index of variability' (IV) which decreases regularly as the diversity increases and the profiles tend towards a common 'convergence profile'. The calibration procedure is consolidated by a mathematical model based on the Poisson distribution; this theoretical model accounts correctly for the observed convergence behavior. On the basis of this calibration curve, it is possible to estimate the diversity of an unknown antibody mixture from a measure of its IV. We conclude that the functional diversity of natural serum IgM in mice can be estimated at approximately 16,000 clones.

Natural and induced tolerance in an immune network model

It has been proposed that the immune system can be partitioned into central and peripheral immune systems. Recently, Carneiro et al. (1996a, b) proposed a network, model incorporating B and T lymphocytes that explicitly accounts for that partition. This model however, had some limitations that are tackled here. Two main changes were introduced: the average idiotypic connectivity is now an explicit function of time based on empirical evidence; and the activation of T lymphocytes by antigen is described by a log-bell shaped dose response curve. The new model, which also accounts for the CIS and PIS distinction, shows more reasonable results since the frequencies of tolerant, immune or autoimmune responses to an antigen are now correct. The model provides a new interpretation for tolerance induction during the neonatal period, and for the adult tolerance by low or high doses of antigen. It predicts that natural tolerance for antigens available during the neonatal period can be kept indefinitely upon their removal, while tolerance induced in the adult stages is rapidly lost upon transient removal of the antigen. A semiquantitative analysis of the model provides a simple explanation for the different results in terms of the frequency at which a limited set of canonical connectivity structures emerge during ontogenesis.

[Prevalence of dyslipidemias in adult ambulatory laboratory tests from different health care providers]

OBJECTIVE

To detect differences in the prevalence of dyslipidemia in adult ambulatory laboratory tests from three different health care providers, in Salvador-Brazil, 1995.

METHODS

The study was carried out using a probabilistic sample of 24 out of 104 laboratories (approximately equal to 25%) which performed the same enzymatic method for lipid tests with the same quality control. Laboratory tests results were separated into three groups, according to health care provider: Sistema Unico de Saúde (SUS, governamental), Health Maintenance Organizations (HMO), and Private or Patients Health Insurance (PHI). Criteria for dyslipidemias in mg/dl were: total cholesterol > or = 240; LDL-c > or = 160; HDL-c < 35 and triglycerides > or = 200. Prevalence rates, 95% confidence intervals (CI) and chi (2) test were used in the analysis.

RESULTS

From the 5464 adult subjects, 14.8% were from SUS, 31.6%. from HMO and 53.6% PHI. The highest prevalence for hypercholesterolemia--28.0% (CI 24.0; 32.0) and for LDL-c > or = 160mg/dL--30.4% (CI 27.6; 33.2), were found in the HMO group. PHI had the highest prevalence for HDL-c < 35mg/dL--12.3% (CI 10.0; 13.8), and for hypertrygliceridemia--17.8% (CI 16.3; 19.3). Most of the differences among health providers were statistically significant.

CONCLUSION

The best lypid profile observed in subjects from SUS suggests social differences in the prevalence of dyslipidemias. As compared to other dyslipidemias, HDL-c < 35mg/dL prevalence was lower than expected in all three groups. The data may provide insights to medical doctors and other health care professionals regarding the questions of dyslipidemias. It can also provide objective information to the patients and encourage them to change their life styles.

[Prevalence of dyslipidemias in adults in laboratory tests from Salvador, Brazil]

PURPOSE

To determine the prevalence of dyslipidemia in non-hospital laboratory tests of adults from Salvador, Brazil.

METHODS

The study was carried out in subjects from a probabilistic sample of 25% of a total of 104 local laboratories that used the same enzymatic method for lipid analysis with the quality control as recommended by the Brazilian Society of Clinical Analyses. These represented 93% of all non-hospital laboratories of Salvador in 1995. The odd months of 1995 were selected for sampling in the present study. Criteria for dyslipidemias were: total cholesterol > or = 240; LDL > or = 160; HDL < 35 and triglycerides > or = 200 mg/dl. Prevalence rates and their 95% confidence intervals (CI) and chi 2 test were used in the analyses.

RESULTS

Tests from two of the 26 laboratories were not used in the analyses due to file problems or refusal. 7,392 adults were screened, 65% female. We observed prevalence (95% CI) of hypercholesterolemia in 30.0 (27.8; 32.2)%, high LDL in 30.1 (30.8; 35.4)% and hypertriglyceridemia in 30.4 (29.0; 31.4)% of the females. As to the male subjects, prevalences were; 24.0 (20.5; 27.5)% for hypercholesterolemia, 26.1 (22.4; 29.3)% for high LDL, 27.6 (25.7; 29.5)% for hypertriglyceridemia. All gender differences were significant. Low HDL occurred in 15.9 (14.2; 17.8)% of males and in 8.0 (7.1; 8.9)% of females.

CONCLUSION

Dyslipidemia is an important risk factor observed in non-hospital laboratory tests of men and women in Salvador. Our data may provide physicians and other health care professionals with objective information to encourage life-style changes.

Further studies on the problem of immune network modelling

In a previous work we have analysed a family of antibody and B-cell network models (basic AB models) of the immune system. This analysis focused principally on the physiological interpretation of their parameters. Our approach consisted in building a detailed and general mathematical model (referred to as the GIB model) and then simplifying it formally to a version (named the RIB model) that belongs to the family of AB models, but which is more general than the basic AB models. From that study it was clear that some of the assumptions necessary to simplify the GIB model into the RIB one, as well as to recover the basic AB models from the RIB one, are quite unrealistic from a physiological point of view. All this raised the issue of the reliability, or even the heuristic value, of theoretical studies based on current network models for experimental immunologists. One approach to clarify this issue is to ask whether the unrealism of the assumptions implicit in the RIB and AB models entails qualitatively different behaviours between them compared to the GIB one. We initiate here such a work by performing a comparative study of a two-clone system of the AB and RIB models, and a variant of the GIB model in which the different molecular compartments were merged into a single one (labelled IGB model). Because all those models rely critically on certain B-cell activation functions, which constitute the core of an implicit model of individual B-cell reactivity or "local rules", we focused the present numerical study, to a great extent, on two parameters determining those activation functions (Hill coefficient and thresholds). Our results indicate that: (1) the RIB and IGB models display in general a much larger diversity of steady states than the AB models; (2) only under a very restricted parameter regime did all studied models behave similarly; (3) the parameter regime under which the AB and IGB models, but not the RIB one, behave similarly is still rather restricted through not as much as in (2); and (4) even relatively small quantitative changes (within reasonable values) in the postulated "local rules" can induce very large quantitative changes in the behaviour of the AB and RIB models but not the IGB model. In the light of the present results, we discuss the need of postulating a set of "local rules" solidly based on experimental evidence as a necessary condition for the reliability of current network models.

A model of the immune network with B-T cell co-operation. I--Prototypical structures and dynamics

Hitherto, "second generation" network models of the immune system have all been restricted to B-lymphocytes and the Ig molecules they produce. These models have not so far been able to provide a convincing mechanism for the distinction between a "Central Immune System" (CIS) composed of a connected network of lymphocyte clones which couple with "self" antigens in a tolerant mode, and a "Peripheral Immune System" (PIS) composed of clones with little or no supra-clonal organization and which produce classical immune responses when interacting with "non-self" antigens. Here, we present a new network model which explicitly incorporates B-T cell co-operation. In this model, B-cell activation is dependent on T-cell help, and activated T-cells are down-regulated by engagement of their TCRs by soluble Ig. We discuss the underlying biology on which we base the system of ordinary differential equations which defines the present network model. We then illustrate some basic features of the model by examining several prototypical situations with a small number of clones. Depending on the idiotypic connectivity structure, the model exhibits two distinct modes of coupling with antigens: an "immune response" mode in which T- and B-cell clones grow exponentially; and a "tolerant" mode in which T-cell clones are controlled by inclusion of all TCRs in the repertoire of an idiotypic B-cell network. Finally, we discuss the simplifying assumptions of the present model and argue that its range of validity is indeed the region of the state-space of the system where the discrimination between the CIS and the PIS take place.

A model of the immune network with B-T cell co-operation. II--The simulation of ontogenesis

This paper is based on a new model of the immune network which explicitly incorporates B-T cell co-operation. A major feature of this model is the simplifying assumption that inhibition by anti-TCR soluble Ig is the only possible down-regulatory influence on activated T-cells. This model is capable of coupling with antigens in both an "immune response" mode and a "tolerant" mode. In the present paper, we simulate the ontogenesis of the immune system by metadynamical recruitment of T- and B-cell clones from the thymus and the bone marrow, seeking to identify the conditions under which each of these modes of antigen coupling occurs. Achieving the tolerant mode depends principally on four parameters: a high value of SB, the rate of bone-marrow production of B-cells; a relatively high efficiency of T-help through mIg-TCR recognition compared with (MHC + peptide)-TCR interaction; and a relatively high value of the product PR.NA, where PR is the average probability that an Ig recognizes another molecule and NA is the number of antigens which are present throughout ontogeny. Analysis of the conditions under which these two modes can coexist, shows that this is possible when a sufficiently numerous set of founder antigens couple in a tolerant mode, whereas isolated antigens first presented once development is completed couple in an immune response mode. The present model thus provides a possible mechanism for the distinction (hitherto purely descriptive) between a Central Immune System organized as a network and responsible for tolerance, and a Peripheral Immune System responsible for immune responses.

The ontogeny of class-regulation of CD4+ T lymphocyte populations

The differential class-regulation of CD4+ T lymphocyte populations is believed to play a major role in determining the qualitative behaviour of the immune system, and in the fate of immune responses in particular. In this article we propose a model for the dynamics of the Th1 and Th2 subpopulations. We put forward the concept of an 'antigenic niche' which allows us to postulate that the key feature underlying the regulation of Th differentiation pathways is the population dynamics of the lymphocytes themselves. Using this model we are able to account for a number of well established experimental observations which were hitherto apparently unrelated and poorly understood. This suggests that our simplified model might be capturing some essential features of the immune system.

The effects of thalidomide treatment on autoimmune-prone NZB and MRL mice are consistent with stimulation of the central immune system

We describe here some immunomodulatory effects of thalidomide on autoimmune-prone mice. The highly increased synthesis of splenic IgM in NZB mice, of splenic and lymph node IgG of different subclasses in MRL/n mice, and of splenic and lymph node IgG1 in MRL/lpr mice was markedly inhibited by thalidomide treatment. After a single treatment with 3 mg of thalidomide, the following changes were observed in NZB mice: (i) an initial decrease in the numbers of large CD5+ microhigh, and in the numbers of total CD5+ micro-, CD5- microhigh, CD5+ microhigh lymphocyte populations of the pleural cavity followed by a late increase in the numbers of large cells of the three cell populations; (ii) a consistent increase in the numbers of a CD5low microlow pleural lymphoid population; (iii) a consistent reduction in the numbers of splenic large CD5+ B cells and an oscillatory increase in the number of cells with CD5- phenotype; (iv) a late reduction in the numbers of splenic total CD5+ B cells. These results are consistent with the notion that thalidomide controls a disease-associated expansion of B cells in autoimmune prone mouse strains through a stimulatory effect of the drug on the immune system.

Rethinking "shape space": evidence from simulated docking suggests that steric shape complementarity is not limiting for antibody-antigen recognition and idiotypic interactions

The concept of "shape space" is based on the assumption that the relevant properties of individual molecules can be adequately specified by a finite list of N parameters; and that cij, the affinity between molecules i and j, can be specified by an equation of the form: cij = f(xi, xj), where xi and xj are N-dimensional vectors representing the absolute positions of molecules i and j in an objective, referential "shape space", and f is an appropriate function. We have performed simulated docking of the combining sites of immunoglobulin molecules, based on their crystallographic structures. The results suggest that shape complementarity cannot account for the specificity of idiotypic interactions, since in the simulations each pair of docked proteins had a buried surface area as great as that occurring in known complexes. It therefore seems likely that the atomic interactions accounting for the specificity of immunoglobulin recognition are highly relational. This casts doubt on the basic assumptions underlying the shape-space concept, at least in the simple form hitherto used in theoretical modelling of the immune system. In order to be realistic, the dimensionality N would have to be high (more than 20), and the function f would be irregular and discontinuous. Alternatively, if the equation cij = f(xi, xj) is interpreted as a purely formal construction in an abstract "inversion space", its validity is entirely relative to the empirical affinity matrix on which the construction is based. We conclude that at present there is no sure way of adequately characterizing the internal structure of idiotypic affinity matrices; and that models of the immune system should therefore aim at being generic and robust with respect to the structure of the idiotypic affinity matrices of unselected immunoglobulins.