The psychology and policy of overcoming economic inequality

Recent arguments claim that behavioral science has focused - to its detriment - on the individual over the system when construing behavioral interventions. In this commentary, we argue that tackling economic inequality using both framings in tandem is invaluable. By studying individuals who have overcome inequality, "positive deviants," and the system limitations they navigate, we offer potentially greater policy solutions.

The persistence of cognitive biases in financial decisions across economic groups

While economic inequality continues to rise within countries, efforts to address it have been largely ineffective, particularly those involving behavioral approaches. It is often implied but not tested that choice patterns among low-income individuals may be a factor impeding behavioral interventions aimed at improving upward economic mobility. To test this, we assessed rates of ten cognitive biases across nearly 5000 participants from 27 countries. Our analyses were primarily focused on 1458 individuals that were either low-income adults or individuals who grew up in disadvantaged households but had above-average financial well-being as adults, known as positive deviants. Using discrete and complex models, we find evidence of no differences within or between groups or countries. We therefore conclude that choices impeded by cognitive biases alone cannot explain why some individuals do not experience upward economic mobility. Policies must combine both behavioral and structural interventions to improve financial well-being across populations.

Risk factors involved in spread of HCV in patients from sub urban Rawalpindi and their association with existing genotypes

The current epidemiological study was designed to trace the involved risk factors in Hepatitis C Virus (HCV) spread and to identify any association between HCV genotypes and risk factors. Blood samples were taken from 400 participants and viral genotyping was performed in order to find any possible relationship between the risk factors and genotypes. Major genotypes included 3, 1, 4 and several untypeable ones with prevalence rates 65%, 22.5%, 2.75% and 9.75% respectively. Surgery and dental procedure were strongly related to the spread of genotype 3b, while genotype 1b was strongly related to blood transfusion and dental procedures as a single combination risk factor. On the other hand genotypes 1a, 3a, 4 and the untypeable genotypes, were equally affected by all reported risk factors. The probability of occurrence of genotype 3a with reference to dental procedures was 11%. Dental procedures, unsafe injection and surgical procedures are the main risk factors while the blood transfusion in combination with dental procedures has emerged as a potent risk factor in the transmission of HCV.

Intrabiliary rupture of hepatic hydatid cyst: role of ERCP

We report a case of hepatic hydatid cyst presenting with obstructive jaundice following cholecystectomy. ERCP showed intrabiliary cyst rupture with biliary obstruction due to cyst remnants. Endoscopic sphincterotomy was performed and cyst debris removed with complete resolution of symptoms.

Endoscopic retrograde cholangiopancreatographic evaluation of patients with obstructive jaundice

OBJECTIVE

To evaluate the role of endoscopic retrograde cholangiopancreatography (ERCP) in patients with obstructive jaundice.

DESIGN

A retrospective, observational study.

PLACE AND DURATION OF STUDY

The study was carried out at Valley Clinic, Rawalpindi, from January 1999 to January 2002.

SUBJECTS AND METHODS

Two-hundred and twenty-six patients, who underwent ERCP for evaluation of obstructive jaundice were included. ERCP in each case was performed with standard technique and the findings were recorded. Therapeutic procedures like sphincterotomy, Dormia extraction for stone, and stent placements were performed whenever indicated.

RESULTS

Of the 226 patients, 117 (51.8%) were males, and 109 (48.2%) females, their mean age being 51.8+/-16.6 years. Common bile and pancreatic ducts were visualized in 81.8% and 68.1% patients respectively. Growth/masses and stones were commonest causes of obstructive jaundice. Choledocholithias was common in males, while biliary channel related growth/masses were common in females (p-value=0.03). Common bile duct stone clearance rate was 88%, stenting was highly successful in patients with growth and strictures. ERCP related complications were noted in 11 (4.8%) patients.

CONCLUSION

ERCP is an important diagnostic and therapeutic modality for evaluation of patients with obstructive jaundice. Growth/masses and stones are common causes of obstructive jaundice which can be diagnosed and treated with ERCP.

Factors that influence outcome in bracing large curves in patients with adolescent idiopathic scoliosis

STUDY DESIGN

A retrospective review of 51 patients with adolescent idiopathic scoliosis (AIS) treated with a Boston brace for curves ranging from 36 degrees to 45 degrees.

OBJECTIVES

To determine what radiographic or clinical observations may be predictive of outcome.

SUMMARY OF BACKGROUND DATA

Patients with AIS who are braced for curves >35 degrees are less likely to respond to conservative treatment than patients of similar maturity with smaller curves.

METHODS

Skeletally immature patients with AIS with no history of prior treatment were treated with a Boston brace. Cobb angles, vertebral tilt angles, coronal decompensation, apical vertebral translation(s), apical vertebral rotation, lateral trunk shift, rib vertebral angle difference, pelvic tilt, and the lumbar pelvic relationship (LPR) were measured at brace prescription, initial in-brace, brace discontinuation, and follow-up.

RESULTS

At the time of brace discontinuation, 31 patients (61%) were judged treatment successes. With follow-up observation, an additional eight patients progressed beyond 5 degrees, and a total of 16 patients (31%) required surgical correction. Only patients with double curves were found to have radiographic values predictive of outcome. The LPR angle, the association between the thoracic curve vertebral tilt angles and the amount of in-brace correction of the Cobb angle, were significant predictors. A patient's reported wear schedule significantly influenced outcome.

CONCLUSIONS

Patients with a double curve pattern in which the thoracic curve is >35 degrees and the LPR angle is >12 degrees are significantly more likely to demonstrate curve progression. In-brace correction for double curves of at least 25% and a patient's ability to wear the orthosis >18 hours/day significantly increased the likelihood of success.

Modulation of spinal deformities in patients with neurofibromatosis type 1

STUDY DESIGN

A consecutive case retrospective chart and radiographic review.

OBJECTIVES

To determine the incidence of nine radiographic dystrophic features acquired during the process of modulation, and to analyze the statistical correlation of these acquired dystrophic features with clinical progression of a spinal deformity.

SUMMARY OF BACKGROUND DATA

In patients with neurofibromatosis, spinal deformities with seemingly few initial dystrophic features have shown a tendency to acquire dystrophic changes during long-term follow-up periods. Similarly, deformities with dystrophic changes can acquire further dystrophic features. This phenomenon is termed "modulation," a feature unique to spinal deformities in neurofibromatosis. These dystrophic changes may evolve slowly or aggressively, and may spread to other regions as well.

METHODS

A review was done of the clinical records, photographs, radiographs, and other imaging studies of 457 patients referred between 1982 and 1995 with the diagnosis of neurofibromatosis Type 1. One hundred twenty-eight patients were diagnosed with a spinal deformity. Ninety-one patients who had a complete set of clinical and radiographic data were included in the study. Location and type of curve as well as the extent of spinal deformity were studied for their effect on the tendency for modulation. Initial spinal radiographs were analyzed for nine radiographic dystrophic features: rib penciling, vertebral rotation, posterior vertebral scalloping, anterior vertebral scalloping, lateral vertebral scalloping, vertebral wedging, spindling of the transverse process, widened interpedicular distance, and enlarged intervertebral foramina. Subsequent radiographs were analyzed critically for evolution, progression, or spread of these features. Correlation of acquisition in these dystrophic features with clinical progression in the spinal deformity, as measured in increments of scoliosis and kyphosis, was analyzed.

RESULTS

In 81% of patients with spinal deformity diagnosed before 7 years of age and in 25% of patients with such a diagnosis after 7 years of age, evidence of modulation was observed. Location, side, and extent of the deformity and patient gender did not influence the propensity of the deformity to modulate. Correlation of modulation with clinical progression of the deformity showed rib penciling to be the only singular factor statistically influencing risk of progression. Of the deformities that acquired three or more penciled ribs, 87% showed significant clinical progression. No other radiographic dystrophic feature individually influenced progression. However, when three or more of the dystrophic skeletal features were acquired, the risk of progression reached statistical significance in 85% of patients.

CONCLUSIONS

Spinal deformities in patients with neurofibromatosis 1 should be regarded as deformities in evolution. One should resist assigning these evolving deformities to either the dystrophic or nondystrophic end of the spectrum without considering the possibility of modulation across the spectrum. A spinal deformity that develops before 7 years of age should be followed closely for evolving dystrophic features (i.e., modulation). When a curve acquires either three penciled ribs or a combination of three dystrophic features, clinical progression is almost a certainty.

Glycidyl acrylate plasma glow discharged polymers

A homogeneous glycidyl acrylate polymer (GAP) has been grafted on to polytetrafluoroethylene (PTFE) and polyethylene (PE) using a modified plasma glow discharge technique with glycidyl acrylate. The polymeric layer appears to be extremely stable to acidic media and to common organic solvents. The modified surface can be derivatized via epoxy groups with hydroxy and amino compounds including sugars and amino sugars. These derivatized surfaces have been characterized by Fourier transform infrared (FTIR) spectroscopy and contact angle measurements. The wide variety of compounds which can be attached provides flexibility in the design of surfaces for the study of a range of biological interactions.

Lipid-protein interaction. The incorporation of myelin proteolipid apoprotein into phosphatidylcholine bilayers

Bovine myelin proteolipid apoprotein (PLA), obtained in high yield and purity by a novel ultrafiltration procedure, has been used to study the perturbations produced by this protein on phosphatidylcholine bilayers, using infrared spectroscopy, nuclear magnetic resonance and fluorescence polarisation. PLA interacts with phospholipids in a similar manner to other intrinsic proteins. For bilayers in the fluid state, the fatty-acyl chain static order, as measured by deuterium NMR, is slightly increased in the presence of the protein, except at very high PLA concentrations. Phosphorus NMR reveals some perturbation of the phospholipid polar group by PLA, but to a smaller degree than occurs with other intrinsic proteins. An increase in static order above tc (the onset temperature for gel-to-fluid transition) is also detected by infrared spectroscopy. Studies using steady-state polarisation of diphenylhexatriene fluorescence indicate that the microviscosity of the bilayer increases as a function of the protein mole fraction. From these data an estimation of the average number of lipids perturbed per protein monomer has been made, and a figure of 37 phospholipid molecules determined. The data are compatible with a picture of a hydrophobic polypeptide, perturbing the phospholipids close to it, but allowing rapid (greater than 10(4) s-1) exchange with all the lipid molecules in the system.

The interaction of phosphatidylcholine bilayers with Triton X-100

The interaction of multilamellar phosphatidylcholine vesicles with the non-ionic detergent Triton X-100 has been studied under equilibrium conditions, specially in the sub-lytic range of surfactant concentrations. Equilibrium was achieved in less than 24 h. Estimations of detergent binding to bilayers, using [3H]Triton X-100, indicate that the amphiphile is incorporated even at very low concentrations (below its critical micellar concentration); a dramatic increase in the amount of bound Triton X-100 occurs at detergent concentrations just below those producing membrane solubilization. Solubilization occurs at phospholipid/detergent molar ratios near 0.65 irrespective of lipid concentration. The perturbation produced by the surfactant in the phospholipid bilayer has been studied by differential scanning calorimetry, NMR and Fourier-transform infrared spectroscopy. At low detergent concentration (lipid/detergent molar ratios above 3), a reduction in 2H-NMR quadrupolar splitting occurs, suggesting a decrease in the static order of the acyl chains; the same effect is detected by Fourier-transform infrared spectroscopy in the form of blue shifts of the methylene stretching vibration bands. Simultaneously, the enthalpy variation of the main phospholipid phase transition is decreased by about a third with respect to its value in the pure lipid/water system. For phospholipid/detergent molar ratios between 3 and 1, the decrease in lipid static order does not proceed any further; rather an increase in fluidity is observed, characterized by a marked decrease in the midpoint transition temperature of the gel-to-fluid phospholipid transition. At the same time an isotropic component is apparent in both 31P-NMR and 2H-NMR spectra, and a new low-temperature endotherm is detected in differential scanning calorimetric traces. When phospholipid and Triton X-100 are present at equimolar ratios some bilayer structure persists, as judged from calorimetric observations, but NMR reveals only one-component isotropic signals. At lipid/detergent molar ratios below unity, the NMR lines become narrower, the main (lamellar) calorimetric endotherm tends to vanish and solubilization occurs.

Biomembranes as models for polymer surfaces. IV. ESCA analyses of a phosphorylcholine surface covalently bound to hydroxylated substrates

Using a simple chemical process, phosphorylcholine has been deposited covalently on the surface of a variety of hydroxylated polymers as a stable, monomolecular coating. Our goal was to obtain new biomaterials which, due to the chemical similarity of the modified interfaces to the phospholipid head groups present on the extracellular surfaces of blood cell membranes, should exhibit enhanced haemo- and biocompatibility. Our previous analyses by chemical and spectrophotometric methods indicated that sufficient quantities of phosphorylcholine were deposited on glass and silica surfaces to result in appreciable modification of their interfacial properties. In the present study, we have examined a series of modified hydroxylated substrates by ESCA and demonstrate specific chemical modifications on the molecular surfaces of polymeric substrates.

Biomembranes as models for polymer surfaces. III. Characterization of a phosphorylcholine surface covalently bound to glass

A surface layer of phosphorylcholine has been chemically linked with the surface hydroxyl groups present on glass and silica by reaction with mono- and bifunctional reagents. Evidence for the structural integrity of the deposited group was provided by the equimolar association of phosphorus and choline with the reacted surfaces. Modified glass surfaces yielded contact angles which are consistent with those found previously for other models of biological membranes. Covalent modification of the treated surfaces was demonstrated by i.r. spectroscopy via the removal of surface hydroxyl groups. The modified surfaces were thermostable at temperatures up to 375 degrees C for extended periods. The relevance of these results to the generation of new biomaterials is discussed.

Biomembranes as models for polymer surfaces. II. The syntheses of reactive species for covalent coupling of phosphorylcholine to polymer surfaces

We have proposed previously that the biocompatibility of biomaterial surfaces might be improved by mimicking the phospholipid components which are present on the external faces of cellular plasma membranes. This approach may have particular relevance to the generation of haemocompatible surfaces, since the distributional asymmetry of phospholipids in the plasma membranes of blood cells is critical to the maintenance of haemostasis. The simplest feature common to the external faces of essentially all the mammalian plasma membranes investigated so far is the high content of the electrically neutral, but zwitterionic, phosphorylcholine. The present communication describes the syntheses of a group of novel reactive species capable of covalently linking phosphorylcholine to a variety of polymer surfaces.

A difference infrared spectroscopic study of gramicidin A, alamethicin and bacteriorhodopsin in perdeuterated dimyristoylphosphatidylcholine

Difference infrared spectroscopy has been used to study the way in which the intrinsic molecules gramicidin A, alamethicin and bacteriorhodopsin perturb their environment when present within a lipid bilayer structure. Dimyristoylphosphatidylcholine containing perdeuterated chains has been used to enable the lipid chain C-2H stretching absorption band to be separated from the C-H bands arising from the intrinsic polypeptide or protein. The C-2H stretching bands of the phospholipid are sensitive to two different types of chain conformation. The C-2H stretching frequency provides information about the static order of the lipid chains, whilst the half-maximum bandwidth provides a measure of chain librational and torsional motion. From the measurements it is concluded that: (1) Above the lipid phase transition temperature tc, low concentrations of either gramicidin A or alamethicin cause a small decrease in lipid chain gauche isomers whilst bacteriorhodopsin in the lipid bilayer has no effect. At higher concentrations each intrinsic molecule causes an increase to occur in lipid chain gauche isomers. (2) The lipid acyl chain motion, as deduced from the bandwidths is increased by the presence of a low concentration of gramicidin A within the lipid bilayer. The presence of the other intrinsic molecules studied have little effect. A higher concentration of alamethicin causes a decrease in chain motion whilst gramicidin A and bacteriorhodopsin have no effect. (3) Below tc each of the intrinsic molecules when present in the lipid bilayer causes an increase in gauche isomers to occur as well as an increase in the lipid chain motion. A broadening of the lipid phase transition occurs as the concentration of the polypeptide increases.

The biosynthetic incorporation of diacetylenic fatty acids into the biomembranes of Acholeplasma laidlawii A cells and polymerisation of the biomembranes by irradiation with ultraviolet light

Acholeplasma laidlawii A has been grown in media containing synthetic, long chain C20- and C23-fatty acids possessing a diacetylene group in their acyl chains. Growth on the C23 diacetylenic acid was poor but was good on the C20 acid. Biosynthetic incorporation of the fatty acids occurs; as much as 90% of the membrane lipid fatty acyl chains consisting of the C20-diacetylenic fatty acid, the remainder being shorter chain, saturated fatty acids. The thermal phase transition of this biomembrane has been studied and a differential scanning calorimetry heating curve shows the presence of an endotherm corresponding to a membrane lipid phase transition occurring at about 26 degrees C. The lipid class composition of membranes containing the C20-diacetylene lipids was examined and found to be similar to membranes from cells grown on oleic acid-containing medium. (The ratio of monoglucosyl- to diglucosyldiacylglycerols was the same but the ratio of glycolipid to phosphatidylglycerol was higher in the cells grown with diacetylene fatty acids). Upon irradiation with ultraviolet light the cells and isolated biomembranes become coloured, either red or yellow depending upon their thermal history. The colour change indicates that extensive cross-linking of the lipids of the biomembranes of A. laidlawii has occurred and that a conjugated polymeric structure has been formed. Analysis of the extracted lipids from the biomembranes by GLC indicates that extensive cross-linking of the lipid chains within the biomembrane of a natural cell system has been achieved. The monoglucosyldiacylglycerols cross-link more readily that do the phosphatidylglycerol lipids. The effect of such lipid cross-linking or polymerisation on the activity at 35 degrees C of an intrinsic membrane-bound enzyme, NADH oxidase, and ribonuclease, an extrinsic membrane-bound enzyme, was studied. The NADH oxidase activity decreased rapidly upon cross-linking of the lipid environment whereas ribonuclease activity was unaffected. The potential for future studies of polymerised model and natural biomembranes is discussed.