Hyperfunctioning papillary thyroid carcinoma - a case report and literature review.

BACKGROUND: Malignant hyperfunctioning thyroid nodules are rare and more likely to occur in follicular cancer types rather than papillary variants. The authors present a case of a papillary thyroid carcinoma associated with a hyperfunctioning nodule. METHODS: A single adult patient submitted to total thyroidectomy with the presence of thyroid carcinoma within hyperfunctioning nodules was selected. Additionally, brief literature was conducted. RESULTS: An asymptomatic 58-year-old male was subjected to routine blood analysis and a TSH level of <0.003 mIU/L was found. Ultrasonography revealed a 21 mm solid, hypoechoic, and heterogenous nodule with microcalcifications in the right lobe. A fine needle aspiration guided by ultrasound resulted in a follicular lesion of undetermined significance. A 99mTc thyroid scintigram was followed and identified a right-sided hyperfunctioning nodule. Another cytology was performed and a papillary thyroid carcinoma was derived as a result. The patient underwent a total thyroidectomy. Postoperative histology confirmed the diagnosis and a tumor-free margin with no vascular or capsular invasions. CONCLUSION: Hyperfunctioning malignant nodules are a rare association, although a careful approach should be led since major clinical implications arise. Selective fine needle aspiration in all suspicious ≥1 cm nodules should be considered.

Ophthalmologic Manifestations of Wolfram Syndrome: Report of 14 Cases.

PURPOSE: The aim of this study was to describe ophthalmological abnormalities in 14 cases of Wolfram syndrome belonging to 9 different families. METHODS: Patients were submitted to a complete ophthalmological, neurological, otorhinolaryngological, urological, and genetic evaluation. RESULTS: Our sample comprised 14 Caucasian patients belonging to 9 different families. Their ages ranged from 10 to 38 years. The mean duration of known disease was 11.3 ± 8.7 years. Genetic confirmation was obtained in 7 families. There was a parental consanguinity history in 2 families. Five families were homozygous for a mutation of exon 8 of the WFS1 gene (Chr. 4), and 2 patients were heterozygous. Diabetes mellitus was the first manifestation in all except 1 patient. The mean age at diagnosis was 8.7 years (range 3-22). None had diabetic retinopathy. The mean age at diagnosis of optic atrophy was 11.1 years (range 8-35). The best-corrected visual acuity ranged from counting fingers to 20/50. CONCLUSIONS: Association of optic atrophy with insulin-dependent diabetes mellitus should raise the suspicion of Wolfram syndrome.

Predicting volleyball serve-reception at group level.

In a group-serve-reception task, how does serve-reception become effective? We addressed "who" receives/passes the ball, what task-related variables predict action mode selection and whether the action mode selected was associated with reception efficacy. In 182 serve-receptions we tracked the ball and the receivers' heads with two video-cameras to generate 3D world-coordinates reconstructions. We defined receivers' reception-areas based on Voronoi diagrams (VD). Our analyses of the data showed that this approach was accurate in describing "who" receives the serve in 95.05% of the times. To predict action mode selection, we used variables related to: serve kinematics, receiver's movement and on-court positioning, the relation between receiver and his closest partner, and interactions between receiver-ball and receiver-target. Serve's higher initial velocities together with higher maximum height, as well as smaller longitudinal distances between receiver and target increased the chances for the use of the overhand pass. Conversely, decreasing alignment of the receiver with the ball and the target increased the chances of using the underhand-lateral pass. Finally, the use of the underhand-lateral pass was associated with lower quality receptions. Behavioural variability's relevance for serve-reception training is discussed.

Photophysical Characterization and in Vitro Phototoxicity Evaluation of 5,10,15,20-Tetra(quinolin-2-yl)porphyrin as a Potential Sensitizer for Photodynamic Therapy.

Photodynamic therapy (PDT) is a selective and minimally invasive therapeutic approach, involving the combination of a light-sensitive compound, called a photosensitizer (PS), visible light and molecular oxygen. The interaction of these per se harmless agents results in the production of reactive species. This triggers a series of cellular events that culminate in the selective destruction of cancer cells, inside which the photosensitizer preferentially accumulates. The search for ideal PDT photosensitizers has been a very active field of research, with a special focus on porphyrins and porphyrin-related macrocycle molecules. The present study describes the photophysical characterization and in vitro phototoxicity evaluation of 5,10,15,20-tetra(quinolin-2-yl)porphyrin (2-TQP) as a potential PDT photosensitizer. Molar absorption coefficients were determined from the corresponding absorption spectrum, the fluorescence quantum yield was calculated using 5,10,15,20-tetraphenylporphyrin (TPP) as a standard and the quantum yield of singlet oxygen generation was determined by direct phosphorescence measurements. Toxicity evaluations (in the presence and absence of irradiation) were performed against HT29 colorectal adenocarcinoma cancer cells. The results from this preliminary study show that the hydrophobic 2-TQP fulfills several critical requirements for a good PDT photosensitizer, namely a high quantum yield of singlet oxygen generation (Φ∆ 0.62), absence of dark toxicity and significant in vitro phototoxicity for concentrations in the micromolar range.

Real-World Evidence of the Long-Term Effectiveness of 0.2 µg/Day Fluocinolone Acetonide Implant in Persistent and Recurrent Diabetic Macular Edema - A Single Center Study.

Purpose: To report the long-term functional, anatomical and safety outcomes of 0.2 µg/day fluocinolone acetonide 0.19mg in patients with persistent or recurrent diabetic macular edema (DME). Methods: Retrospective, observational, single-center study of patients with recurrent or persistent DME. All patients received 0.2 µg/day of fluocinolone acetonide 0.19mg, and data were collected at baseline and months 1, 3, 6, 12, 24 and 36 after implantation. Outcomes measured included best-corrected visual acuity (BCVA), central macular thickness (CMT), intraocular pressure (IOP), and safety outcomes. Results: A total of 28 eyes from 28 patients were included. The mean age was 66.5 years (95% CI 62.8-70.2) with a mean duration of DME of 8.8 years (95% CI 7.7-10.0). Only two eyes were phakic. Mean follow-up was 25.4 months (95% CI 21.2-29.6). Mean BCVA at baseline was 48.6 ETDRS letters (95% CI 41.3-55.8) and improved as early as month 1 of follow-up with a mean gain in BCVA of 7.8 (95% CI 4.3-11.3) ETDRS letters (p<0.001). Statistically significant improvements in BCVA were also observed at months 6, 12 and 24. At baseline, patients had a mean CMT of 530.5µm (95% CI 463.0-598.0), and a decrease in CMT was observed, starting at the first month of follow-up (mean CMT reduction of -170.5µm, 95% CI -223.8- -117.1; p<0.001). Statistically significant decreases in CMT were also observed at months 6, 12, 24, and 36, with the maximum decrease observed at month 12 (p<0.001). Mean IOP at baseline was 16.4mmHg (95% CI 15.3-17.5) and nine eyes (32.1%) had an IOP ≥21mmHg during follow-up. Conclusion: Our results support the effectiveness and safety profile of fluocinolone acetonide. Although additional long-term real-world evidence is required, fluocinolone acetonide may represent a safe strategy for daily, low-dose, sustained and localized release to the posterior segment of the eye, providing both functional and anatomical benefits in DME.

Design and Development of a Web-Based Prospective Nationwide Registry for Ocular Inflammatory Diseases: UVEITE.PT - The Portuguese Ocular Inflammation Registry.

Uveitis is a heterogeneous collection of infrequent diseases, which poses significant challenges to cost-effective research in the field. Medical registries are being increasingly recognized as crucial tools to provide high-quality data, thus enabling prospective clinical research. This paper describes the design and technical structure development of an innovative countrywide electronic medical record for uveitis, Uveite.pt, and gives an overview of the cohort registered since its foundation, March 2020.Uveite.pt is an electronic medical record platform developed by the Portuguese Ocular Inflammation Group (POIG), a scientific committee of the Portuguese Ophthalmology Society. This is a nationwide customized web-based platform for uveitis patients useful for both clinical practice and real-world-based research, working as a central repository and reporting tool for uveitis. This paper describes the technical principles, the design and the development of a web-based interoperable registry for uveitis in Portugal and provides an overview of more than 400 patients registered in the first 18 months since inception.In infrequent diseases, the existence of registries enables to gather evidence and increase research possibilities to clinicians. The adoption of this platform enables standardization and improvement of clinical practice in uveitis. It is useful to apprehend the repercussion of medical and surgical treatments in uveitis and scleritis, supporting clinicians in the strict monitoring of drug adverse reactions and surgical outcomes.

Understanding the interaction between trivalent lanthanide ions and stereoregular polymethacrylates through luminescence, binding isotherms, NMR, and interaction with cetylpyridinium chloride.

Complexation of isotactic, syndiotactic, and atactic poly(methacrylic acid), PMA, with trivalent lanthanide ions has been studied in water at a degree of neutralization 0.5. Metal ion binding is shown by quenching of cerium(III) fluorescence, enhancement of Tb(III) luminescence, and lanthanide-induced line broadening in the PMA (1)H NMR spectra. Comparison with lanthanide-acetate complexation suggests carboxylate binds in a bidentate fashion, while Ce(III) luminescence quenching suggests an ≈3:1 carboxylate:metal ion stoichiometry, corresponding to charge neutralization. The presence of both free and bound Ce(III) cations in PMA solutions is confirmed from luminescence decays. Studies of Tb(3+) luminescence lifetime in H2O and D2O solutions show complexation is accompanied by loss of 5-6 water molecules, indicating that each bidentate carboxylate replaces two coordinated water molecules. The behavior depends on pH and polyelectrolyte stereoregularity, and stronger binding is observed with isotactic polyelectrolyte. Binding of cetylpyridinium chloride, CPC, in these systems is studied by luminescence, NMR, and potentiometry. NMR and Tb(3+) luminescence lifetime studies show the strongest binding with the isotactic polymer. Binding of surfactant to poly(methacrylate) in the presence of lanthanides is noncooperative, i.e., it binds to the free sites; binding isotherms in the presence of lanthanides are shifted to higher free surfactant concentrations, compared with sodium ions, have lower slopes and show a clear two-step binding mechanism. While CPC readily replaces the Na(+) ions of poly(methacrylate) and binds very strongly (low critical association concentrations), exchange is much more difficult with the strongly bound trivalent lanthanide ions. Effects of tacticity are seen, with surfactant interacting most strongly with isotactic chains in the initial stages of binding, while in the final stages of binding the interaction is strongest with atactic poly(methacrylate).

Fluorescence quenching of protonated ß-carbolines in water and microemulsions: evidence for heavy-atom and electron-transfer mechanisms.

The fluorescence quenching of protonated ß-carbolines has been investigated in acidic aqueous solutions and in w/o microemulsions using I(-), Br(-), Cu(2+), SCN(-), and Pb(2+) as quenchers. It was found that fluorescence quenching by these compounds is much more efficient in water than in microemulsions since quenching in microemulsions depends on the simultaneous occupancy of the water droplets by both fluorophore and quencher. Linear Stern-Volmer plots were obtained in all cases, leading to quenching rate constants of ca. 10(8)-10(10) M(-1) s(-1) in water and ca. 10(7)-10(8) M(-1) s(-1) in microemulsions. In the case of quenching by SCN(-), ns flash photolysis studies indicate formation of (SCN)2(˙-) showing that at least part of the quenching process involves an electron transfer mechanism. This indicates that the singlet excited states of the protonated ß-carbolines can act as relatively strong oxidants (E° > 1.6 V), capable of oxidizing many species, including the biologically relevant DNA base guanine. The observation of the (SCN)2(˙-) transient in microemulsions demonstrates that it is possible to have the protonated ß-carboline and at least two thiocyanate ions in the same water pool.

Selective fluorescence quenching in cationic fluorene-thiophene diblock copolymers for ratiometric sensing of anions.

The cationic, all-conjugated AB diblock copolymer poly[9,9-bis(2-ethylhexyl)fluorene]-b-poly[3-(6-trimethylammoniumhexyl) thiophene] bromide (PF2/6-b-P3TMAHT) shows dual fluorescence from the poly(fluorene) (PF) and poly(thiophene) (PT) blocks. A comparison of fluorescence quenching of the cationic PT block fluorescence with unquenched PF block provides a sensitive ratiometric method for anion sensing. The application to analysis of halide ions, single- and double-stranded DNA is demonstrated. High selectivity is observed with halide ions, with the strongest quenching being seen with iodide. The quenching with DNA can be used for nucleic acid quantification at sub-µM concentrations.

Vitrectomy and tumor endoresection for the diagnosis and treatment of focal nodular retinal gliosis.

We report the case of a 60-year-old woman who presented with metamorphopsia and progressive vision loss in the right eye. Fundus examination revealed an elevated, white-yellow mass in the peripheral inferotemporal retina, with massive retinal exudation, proliferative vitreoretinopathy, and retinal detachment. Pars plana vitrectomy with tumor endoresection was performed, and a complete excisional biopsy of the lesion was obtained by removing the tumor through the anterior chamber. Histopathological analysis of the specimen confirmed a diagnosis of peripheral, focal, nodular retinal gliosis. Postoperatively, visual function improved greatly, with no recurrence of the disease at 12 months' follow-up. Focal nodular retinal gliosis is a rare, non-neoplastic proliferation of retinal glial cells, with a vascular component. In our case, surgical treatment with pars plana vitrectomy facilitated accurate diagnosis and resulted in effective management of the retinal tumor and associated complications.

Sources of Sport Satisfaction and Perceived Self-Efficacy Among Youth in a Competitive Environment.

Young people's sources of satisfaction in sport are an important indicator of their long-term sport participation. Contextual factors and an individual's internal dispositions act synergistically to determine a positive experience. We studied sources of sport satisfaction and perceived self-efficacy of 1,151 male and female youth athletes (M age = 14.72, SD = 1.56 years) in Brazil who were engaged in school state level competition. The participants responded to questionnaires on their sport satisfaction and perceived self-efficacy. We considered sex, training time, and last game results as independent variables in accessing participant differences in perceived satisfaction. We observed an increasing trend toward more significant satisfaction as sport experience increased. Perceived self-efficacy was a moderator for young participants' self-reported positive experience in sports. Thus, in our offer of evidence on sources of satisfaction in sport and perceived self-efficacy among youth in competition, we found the extent of the sport experience and self-efficacy to be important factors in the developmental pathway.

The 2021 Portuguese Society of Ophthalmology joint guidelines with Paediatric Rheumatology on the screening, monitoring and medical treatment of juvenile idiopathic arthritis-associated uveitis.

AIM: To develop the first Ophthalmology joint guidelines with Paediatric Rheumatology with recommendations on the screening, monitoring and medical treatment of juvenile idiopathic arthritis-associated uveitis (JIA-U), endorsed by the Portuguese Society of Ophthalmology (SPO). METHODS: A systematic literature review was conducted to include publications up to July 14th 2020, with no language restrictions, in order to include all the international position papers/guidelines concerning the medical management of JIA-U and randomised clinical trials assessing the efficacy and safety of medical treatment in this field. We searched through MEDLINE (PubMed), Scopus, Web of Science and Cochrane Library. The Delphi modified technique to generate consensus was used. Preliminary evidence statements were subject to an anonymous agreement assessment and discussion process using an online survey, followed by further discussion and update at a national meeting. A draft of the manuscript with all recommendations was then circulated among all participants and suggestions were incorporated. The final version was again circulated before publication. RESULTS: Twenty-six recommendations were developed focusing on the following topics: general management (3), screening and follow-up of uveitis (4), treatment (17) and health education in JIA-U among patients and families (2). CONCLUSION: These guidelines were designed to support the shared medical management of patients with JIA-U and emphasize the need for a multidisciplinary approach between Ophthalmology and Paediatric Rheumatology regarding the comprehensive care of JIA-U. We acknowledge that updating these recommendations will be warranted in the future, as more evidence becomes available. KEY-WORDS: juvenile idiopathic arthritis, uveitis, biological treatment, conventional immunosuppressive treatment, multidisciplinary management, guidelines, consensus, review, Delphi Technique.

Arterial thromboembolic events in patients with exudative age-related macular degeneration treated with intravitreal bevacizumab or ranibizumab.

BACKGROUND/AIMS: To compare retrospectively the incidence of arterial thromboembolic events (ATEs) in patients treated with bevacizumab or ranibizumab for exudative age-related macular degeneration. METHODS: Charts of 378 patients treated with at least 1 intravitreal injection of ranibizumab or bevacizumab were reviewed to calculate the incidence of ATEs. Only patients under monotherapy were analyzed. RESULTS: ATEs occurred in 15 patients: 12 (12/97) with bevacizumab (12.4%) and 3 (3/219) with ranibizumab (1.4%) - odds ratio 10.16; 95% confidence interval 2.80-36.93; p < 0.0001. ATEs in the bevacizumab and ranibizumab cohorts included stroke, myocardial infarction, angina pectoris, peripheral thromboembolic disease, transient ischemic attack, sudden death and lethal stroke. CONCLUSION: In this series, bevacizumab raised the risk of ATEs when compared to ranibizumab. In an elderly population with multiple cardiovascular risk factors, the new ATEs may not be attributed exclusively to the intravitreal bevacizumab administration. These findings raise an issue that must be confirmed in randomized clinical trials.

Do Drug-likeness Rules Apply to Oral Prodrugs?

This paper describes a comparative analysis of the physicochemical and structural properties of prodrugs and their corresponding drugs with regard to drug-likeness rules. The dataset used in this work was obtained from the DrugBank. Sixty-five pairs of prodrugs/drugs were retrieved and divided into the following categories: carrier-linked to increase hydrophilic character, carrier-linked to increase absorption, and bioprecursors. We compared the physicochemical properties related to drug-likeness between prodrugs and drugs. Our results show that prodrugs do not always follow Lipinski's Rule of 5, especially as we observed 15 prodrugs with more than 10 hydrogen bond acceptors and 18 with a molecular weight greater than 500 Da. This fact highlights the importance of extending Lipinski's rules to encompass other parameters as both strategies (filtering of drug-like chemical libraries and prodrug design) aim to improve the bioavailability of compounds. Therefore, critical reasoning is fundamental to determine whether a structure has drug-like properties or could be considered a potential orally active compound in the drug-design pipeline.

Interpersonal pattern dynamics and adaptive behavior in multiagent neurobiological systems: conceptual model and data.

Ecological dynamics characterizes adaptive behavior as an emergent, self-organizing property of interpersonal interactions in complex social systems. The authors conceptualize and investigate constraints on dynamics of decisions and actions in the multiagent system of team sports. They studied coadaptive interpersonal dynamics in rugby union to model potential control parameter and collective variable relations in attacker-defender dyads. A videogrammetry analysis revealed how some agents generated fluctuations by adapting displacement velocity to create phase transitions and destabilize dyadic subsystems near the try line. Agent interpersonal dynamics exhibited characteristics of chaotic attractors and informational constraints of rugby union boxed dyadic systems into a low dimensional attractor. Data suggests that decisions and actions of agents in sports teams may be characterized as emergent, self-organizing properties, governed by laws of dynamical systems at the ecological scale. Further research needs to generalize this conceptual model of adaptive behavior in performance to other multiagent populations.

Tocilizumab in refractory juvenile idiopathic arthritis with associated uveitis: a case report.

INTRODUCTION: We report a 9-year follow-up of a child with refractory juvenile idiopathic arthritis (JIA) with associated uveitis in which tocilizumab proved to be effective in achieving disease control. CASE REPORT: A 16-month child was diagnosed with JIA and at the age of 3 developed bilateral non-granulomatous anterior uveitis. Throughout the follow-up, the patient presented frequent joint and ocular flares. Refractory anterior uveitis and topical corticosteroid therapy resulted in the development of bilateral cataract and high intraocular pressure (IOP). The patient underwent multiple ocular surgeries along with corticosteroids, immunosuppressive therapy with Methotrexate and Adalimumab failing to reach disease control. Only after the introduction of Tocilizumab a lower disease activity was achieved. DISCUSSION: Management of JIA-associated uveitis is challenging and requires a close collaboration between paediatric rheumatologists and ophthalmologists. Clinical remission can be difficult to achieve. However, one should always pursuit JIA inactivity with IOP and inflammation control. This report supports Tocilizumab as a useful therapeutic option for JIA-associated uveitis.

Effects of Charge Density on Photophysics and Aggregation Behavior of Anionic Fluorene-Arylene Conjugated Polyelectrolytes.

Three anionic fluorene-based alternating conjugated polyelectrolytes (CPEs) have been synthesized that have 9,9-bis(4-phenoxy-butylsulfonate) fluorene-2,7-diyl and 1,4-phenylene (PBS-PFP), 4,4'-biphenylene (PBS-PFP2), or 4,4″-p-terphenylene (PBS-PFP3) groups, and the effect of the length of the oligophenylene spacer on their aggregation and photophysics has been studied. All form metastable dispersions in water, but can be solubilized using methanol, acetonitrile, or dioxane as cosolvents. This leads to increases in their emission intensities and blue shifts in fluorescence maxima due to break-up of aggregates. In addition, the emission maximum shifts to the blue and the loss of vibronic structure are observed when the number of phenylene rings is increased. Debsity Functional Theory (DFT) calculations suggest that this is due to increasing conformational flexibility as the number of phenylene rings increases. This is supported by increasing amplitude in the fast component in the fluorescence decay. The nonionic surfactant n-dodecylpentaoxyethylene glycol ether (C12E5) also breaks up aggregates, as seen by changes in fluorescence intensity and maximum. However, the loss in vibrational structure is less pronounced in this case, possibly due to a more rigid environment in the mixed surfactant-CPE aggregates. Further information on the aggregates formed with C12E5 was obtained by electrical conductivity measurements, which showed an initial increase in specific conductivity upon addition of surfactants, while at higher surfactant/CPE molar ratios a plateau was observed. The specific conductance in the plateau region decreased in the order PBS-PFP3 < PBS-PFP2 < PBS-PFP, in agreement with the change in charge density on the CPE. The reverse process of aggregate formation has been studied by injecting small volumes of solutions of CPEs dissolved at the molecular level in a good solvent system (50% methanol-water) into the poor solvent, water. Aggregation was monitored by changes in both fluorescence and light scattering. The rate of aggregation increases with hydrophobicity and concentration of sodium chloride but is only weakly dependent on temperature.

Assessment of the use of vitamin C and E supplements concomitantly to antibiotic treatment against Helicobacter pylori: A systematic review and meta-analysis. / Evaluación del suplemento de vitaminas C y E en el tratamiento antibiótico contra Helicobacter pylori: revisión sistemática y metaanálisis.

INTRODUCTION: Helicobacter pylori infections affect almost 50% of the world population, constituting a risk factor for benign and malignant gastrointestinal diseases. The increased resistance to antibiotic treatment against this infection represents a dilemma in the search of other therapeutic alternatives. OBJECTIVE: To determine the efficacy of the use of vitaminC and E supplements concomitantly to antibiotic treatment against H. pylori infections. METHODS: We performed a systematic review on the MedLine (PubMed), Embase and Cochrane Central Register of Clinical Trials (CENTRAL) databases, searching for studies evaluating the efficacy of vitaminC and/or E supplements in the antibiotic treatment of H. pylori infections. The primary outcome was eradication of the infection. The secondary outcome was the adverse effects. The meta-analysis was conducted using the random effects method. RESULTS: Ten studies were included and analyzed in two groups. The first group, which was comprised by 973patients, compared the use of supplementation with vitaminC and E, showing that, without discriminating the number of antibiotics used, there was no relationship with the eradication of the infection (OR: 1.98 [95%CI: 0.92-4.29] P=.08). The triple or quadruple antibiotic therapy had no effect on eradication rates either (OR 1.80 [95%CI: 0.64-5.08] P=.26 and OR: 2.84 [95%CI: 0.51-15.56] P=.22, respectively). No effect on the eradication rates was observed either in the group that only assessed the use of vitaminC, comprised by 702patients (OR: 1.17 [95%CI: 0.58-2.31] P=.65). Only four studies reported adverse effects, the most common one being nausea. CONCLUSIONS: Supplementation with vitaminC and E in the antibiotic treatment against H. pylori has no effect. However, the reviewed studies had several biases and differences in the dosage of the supplements and antibiotics administered.

Interplay of electrostatic and hydrophobic effects with binding of cationic gemini surfactants and a conjugated polyanion: experimental and molecular modeling studies.

Understanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS-PFP) and cationic gemini surfactants alpha,omega-(CmH2m+1N+(CH3)2)2(CH2)s(Br-)2 (m-s-m; m=12, s=2, 3, 5, 6, 10, and 12) has been studied experimentally in aqueous solution. These surfactants are chosen to see whether molecular recognition and self-assembly occurs between the oppositely charged conjugated polyelectrolyte and gemini surfactant when the spacer length on the surfactant is similar to the intercharge separation on the polymer. Without surfactants, PBS-PFP exists as aggregates. These are broken up upon addition of gemini surfactants. However, as anticipated, the behavior strongly depends upon spacer length (s). Fluorescence measurements show three surfactant concentration regimes: At low concentrations (<2x10(-6) M) quenching occurs and is most marked with the small spacer 12-2-12; at intermediate concentrations (approximately 2x10(-6)-10(-3) M), fluorescence intensity is constant, with a 12-carbon spacer 12-12-12 showing the strongest fluorescence; above the critical micelle concentration (CMC; approximately 10(-3) M) increases in emission intensity are seen in all cases and are largest with the intermediate spacers 12-5-12 and 12-6-12, where the spacer length most closely matches the distance between monomer units on the polymer. With longer spacer length surfactants, surface tension measurements for concentrations below the CMC reveal the presence of polymer-surfactant aggregates at the air-water interface, possibly reflecting increased hydrophobicity. Above the CMC, small-angle neutron scattering experiments for the 12-6-12 system show the presence of spherical aggregates, both for the pure surfactant and for polyelectrolyte/gemini mixtures. Molecular dynamics simulations help rationalize these observations and show that there is a very fine balance between electrostatic and hydrophobic interactions. With the shortest spacer 12-2-12, Coulombic interactions are dominant, while for the longest spacer 12-12-12 the driving force involves hydrophobic interactions. Qualitatively, with the intermediate 12-5-12 and 12-6-12 systems, the optimum balance is observed between Coulombic and hydrophobic interactions, explaining their strong fluorescence enhancement.