Psychosocial consequences of developmental prosopagnosia: a problem of recognition

OBJECTIVE

To provide the first systematic in-depth description of the consequences of developmental prosopagnosia (DP; 'face blindness') for psychosocial functioning and occupational disability, in order to determine what kind of professional intervention may be needed.

METHODS

Semi-structured telephone interviews were carried out with 25 people whose self-reports of face recognition problems were confirmed by impaired scores on the Cambridge Face Recognition Test. Thematic analysis was used to inductively identify and understand common psychosocial consequences of DP.

RESULTS

All participants described recurrent and sometimes traumatic social interaction difficulties caused by recognition problems, such as failing to recognize close friends, work colleagues, and family members. These problems often led to chronic anxiety about offending others and feelings of embarrassment, guilt, and failure. Most participants described some degree of fear and avoidance of social situations in which face recognition was important, including family and social gatherings, and meetings at work. Long-term consequences could include dependence on others, a restricted social circle, more limited employment opportunities, and loss of self-confidence.

CONCLUSION

The potential for negative psychosocial consequences and occupational disability posed by DP is as great as that posed by conditions which are currently afforded professional recognition and support, such as stuttering and dyslexia. Wider recognition of the problems prosopagnosia can cause could reduce anxiety about social interaction difficulties by making it easier to explain and justify recognition problems to other people, including employers. Greater professional awareness could facilitate detection and referral of those requiring support with coping with social interactions.

Serial lung function tests in primary immune deficiency

Pulmonary complications are common in patients with primary immune deficiency (PID). The aim of this study was to assess the usefulness of lung function tests (LFTs) in the management of these patients, and in particular to see if carbon monoxide transfer factor (TLCO) is needed in addition to spirometry. We studied 20 patients (11 female) with PID in a tertiary referral clinic, with a mean age of 47.6 years. Serial LFTs, spanning a mean of 101 months, were correlated with immunoglobulin levels and antibiotic usage. Seven patients showed a decline in forced expiratory volume in 1 second over the period of the study. An additional five patients showed a decline in TLCO. Of these 12 patients, two had no radiographic evidence of lung disease. Higher levels of immunoglobulin were associated with slower decline in LFTs (P < 0.05). The analysis of antibiotic usage and LFTs failed to show a statistically significant effect, although there was a trend towards a slower rate of decline with greater use of antibiotics. LFTs decline slowly in patients with PID. Annual testing (both spirometry and transfer factor) is useful in the assessment of these patients, and should not be confined to those with radiological evidence of lung disease.

Cohesive, multicomponent, dense powder flow characterization by NIR

Non-aerated powder flows are frequently encountered in downstream pharmaceutical processes. Such flows occur at the entrance of powder compression units, and their characteristics are of great interest because any powder agglomeration or segregation can be detrimental to the quality of the final solid oral dosage form. This work was aimed at developing a process analytical technology (PAT) method, based on near-infrared spectroscopy (NIR) for the in-line powder flow characterization of pharmaceutical formulations. An Ibuprofen drug formulation was selected for study. A bench-scale hopper system was assembled to monitor powder flow behaviour. An in-line commercial NIR Axsun spectrometer and probe were chosen to collect in-line spectral data on dense, multicomponent, non-aerated powder flow prior to compression. Spectra were collected on flowing mannitol and pharmaceutical product blends. A specially designed, non-contact sampling interface allowed the collection of representative process powder flow spectra without affecting blend uniformity. A partial least squares chemometric model was developed for laboratory-prepared samples, to quantitatively determine the flowing powder's active pharmaceutical ingredient (API) level. Static sample spectra and flowing pure mannitol spectra proved to have a high degree of reproducibility. The model's standard error of calibration was 2.95% of the API level with a R2 of 0.991. Flowing blend powder spectra and API estimates showed variations consistent with those seen in model samples. The average values for flowing pharmaceutical blends were close to the API concentration, indicating that the proposed procedure was statistically acceptable. The model is considered very promising, and some improvements would lead to its final acceptance at production scale as a PAT tool.

Risk factors for 1-year mortality after postoperative mediastinitis

OBJECTIVE

Postoperative mediastinitis after median sternotomy is associated with disability and mortality. The aim of this study was to identify risk factors for mortality 1 year after postoperative mediastinitis diagnosis.

METHODS

Postoperative mediastinitis was defined as an organ-space infection involving the mediastinum and necessitating debridement. A total of 183 cases of postoperative mediastinitis were prospectively identified from infection control databases. By using univariate and multivariate analysis, clinical risk factors for 1-year mortality were identified.

RESULTS

Of 183 patients, 36 (19.7%) died within 3 months of the initial operation. Overall, 51 (33%) died during the study period (the median time to death from the date of diagnosis was 37 days [interquartile range, 11,139 days]). In multivariate analysis, independent predictors of 1-year mortality were a greater than 3-day delay in sternal closure after debridement (hazard ratio, 6.27; P < .001), age greater than 65 years (hazard ratio, 2.29; P = .015), serum creatinine level greater than 2 mg/dL before debridement (hazard ratio, 2.52; P = .019), stay in an intensive care unit before sternal debridement (hazard ratio, 5.56; P < .001), and postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus (hazard ratio, 2.13; P = .02). Treatment with antibiotics with in vitro activity against the infecting pathogen within 7 days of initial debridement was associated with a decreased risk for mortality (hazard ratio, 0.40; P = .03).

CONCLUSIONS

Our data suggest that, to improve long-term survival, patients with postoperative mediastinitis should undergo sternal closure within 72 hours after sternal debridement and should receive effective antimicrobial therapy based on operative culture results.

Comparison of measured and calculated radiotherapy doses in the chest region of an inhomogeneous humanoid phantom

Errors in dose calculation by treatment planning computers are known to arise when calculation algorithms do not account for electron disequilibrium near interfaces between tissues of different density. The accuracy of a treatment planning system (Plato, Nucletron International BV) was investigated for two treatments in the chest region: tangential 6 MV photons to the chest wall and opposed AP-PA 18 MV photon fields to the mediastinum. Thermo-luminescent dosimeters were used to measure dose at 40 sites in the chest of a humanoid phantom (Rando, Alderson Associates). Measurements were compared with point doses calculated using two different versions of the Plato external beam calculation software: RTS 1.8 and the newer RTS 2.2. Measured and calculated doses differed by 3% or more at more than one quarter of all sites. The greatest discrepancies occurred for points located in lung, which were generally overestimated. The maximum discrepancies for the 6 MV tangential breast irradiation were 8.5% for RTS 1.8 and 3.5% for RTS 2.2. For the 18 MV opposed field irradiation, the maximum discrepancies were 11.4% and 8.1% respectively. RTS 2.2 was more accurate than RTS 1.8, with smaller mean and maximum discrepancies.

Mutagenic and chemical modification of the ABA-1 allergen of the nematode Ascaris: consequences for structure and lipid binding properties

The polyprotein allergens/antigens of nematodes (NPAs) are the only lipid binding proteins known to be produced as polyproteins. Cleavage of the large polyprotein precursors at regularly spaced proteinase cleavage sites produces 10 or 11 individual protein units of approximately 15 kDa. The sequences of these units are highly diverse within and between species, but there are five absolutely or strongly conserved amino acid positions (Trp15, Gln20, Leu42, Cys64, and Cys120). We have tested the role of these signature amino acids by mutational or chemical alteration of the ABA-1 protein of Ascaris, and examined the resulting modified proteins for perturbations of their lipid binding activities and structural integrity. Substitution of Trp15 and Gln20 both affect the stability of the protein in terms of resistance to thermal or chemical denaturation, but the ligand binding function is unaffected. Mutation of Leu42, however, disrupts both the protein's structural stability and functional integrity, as does chemical disruption of the disulfide bridge formed between Cys64 and Cys120. We also find that the C-terminal, but not the N-terminal, half of the protein binds fatty acids, indicating that the binding site may be confined to this part of the protein. This also supports the idea that the NPA units are themselves derived from an ancient duplication event, and that they may comprise two functionally distinct domains.

A surface-associated retinol- and fatty acid-binding protein (Gp-FAR-1) from the potato cyst nematode Globodera pallida: lipid binding activities, structural analysis and expression pattern

Parasitic nematodes produce at least two structurally novel classes of small helix-rich retinol- and fatty-acid-binding proteins that have no counterparts in their plant or animal hosts and thus represent potential targets for new nematicides. Here we describe a protein (Gp-FAR-1) from the plant-parasitic nematode Globodera pallida, which is a member of the nematode-specific fatty-acid- and retinol-binding (FAR) family of proteins but localizes to the surface of this species, placing it in a strategic position for interaction with the host. Recombinant Gp-FAR-1 was found to bind retinol, cis-parinaric acid and the fluorophore-tagged lipids 11-(dansylamino)undecanoic acid and dansyl-D,L-alpha-amino-octanoic acid. The fluorescence emission characteristics of the dansylated analogues indicated that the entire ligand enters the binding cavity. Fluorescence competition experiments showed that Gp-FAR-1 binds fatty acids in the range C(11) to C(24), with optimal binding at C(15). Intrinsic fluorescence analysis of a mutant protein into which a tryptophan residue had been inserted supported computer-based predictions of the position of this residue at the protein's interior and possibly also at the binding site. Of direct relevance to plant defence systems was the observation that Gp-FAR-1 binds two lipids (linolenic and linoleic acids) that are precursors of plant defence compounds and the jasmonic acid signalling pathway. Moreover, Gp-FAR-1 was found to inhibit the lipoxygenase-mediated modification of these substrates in vitro. Thus not only does Gp-FAR-1 function as a broad-spectrum retinol- and fatty-acid-binding protein, the results are consistent with the idea that Gp-FAR-1 is involved in the evasion of primary host plant defence systems.

Antimicrobial resistance and clinical outcome of Bacteroides bacteremia: findings of a multicenter prospective observational trial

There is debate regarding the correlation between in vitro susceptibility testing and clinical response to therapy for Bacteroides bacteremia. We conducted a prospective multicenter observational study of 128 patients with bacteroides bacteremia. Outcome was correlated with results of in vitro susceptibility testing of Bacteroides isolates recovered from blood and/or nonblood sites, determined with use of 3 end points: mortality at 30 days, clinical response (cure vs. failure), and microbiological response (eradication vs. persistence). The mortality rate among patients who received inactive therapy (45%) was higher than among patients who received active therapy (16%; P=.04). Clinical failure (82%) and microbiological persistence (42%) were higher for patients who received inactive therapy than for patients who received active therapy (22% and 12%, respectively; P=.0002 and.06, respectively). In vitro activity of agents directed at Bacteroides species reliably predicts outcome: the specificity was 97%, and positive predictive value was 82%. Antimicrobial susceptibility testing may be indicated for patients whose blood specimens yield Bacteroides species.

The ABA-1 allergen of Ascaris lumbricoides: sequence polymorphism, stage and tissue-specific expression, lipid binding function, and protein biophysical properties

The ABA-1 protein of Ascaris lumbricoides (of humans) and Ascaris suum (of pigs) is abundant in the pseudocoelomic fluid of the parasites and also appears to be released by the tissue-parasitic larvae and the adult stages. The genes encoding the polyprotein precursor of ABA-1 (aba-1) were found to be arranged similarly in the two taxa, comprising tandemly repeating units encoding a large polyprotein which is cleaved to yield polypeptides of approximately 15 kDa which fall into 2 distinct classes, types A and B. The polyprotein possibly comprises only 10 units. The aba-1 gene of A. lumbricoides is polymorphic, and the majority of substitutions observed occur in or near predicted loop regions in the encoded proteins. mRNA for ABA-1 is present in infective larvae within the egg, and in all parasitic stages, but was not detectable in unembryonated eggs. ABA-1 mRNA was confined to the gut of adult parasites, and not in body wall or reproductive tissues. Recombinant protein representing a single A-type unit for the A. lumbricoides aba-1 gene was produced and found to bind retinol (Vitamin A) and a range of fatty acids, including the pharmacologically active lipids lysophosphatidic acid, lysoplatelet activating factor, and there was also evidence of binding to leukotrienes. It failed to bind to any of the anthelmintics screened. Differential Scanning Calorimetry showed that the recombinant protein was highly stable, and unfolded in a single transition at 90.4 degrees C. Analysis of the transition indicated that the protein occurs as a dimer and that the dimer dissociates simultaneously with the unfolding of the monomer units.

Sequence-divergent units of the ABA-1 polyprotein array of the nematode Ascaris suum have similar fatty-acid- and retinol-binding properties but different binding-site environments

Polyproteins comprise long polypeptides that are post-translationally cleaved into proteins of different function, or tandemly repetitive polypeptides which are processed into multiple versions of proteins which are presumed to have the same function. In the latter case the individual units of the polyprotein can differ substantially in sequence. Identity of function between the different units therefore cannot be assumed. Here we have examined the ABA-1 polyprotein allergen of the parasitic nematode Ascaris suum and found it to contain units which show a 50% difference in amino acid sequence. The parasite therefore produces at least two radically different forms of the allergen encoded within the polyprotein array. In fluorescence-based ligand-binding assays, recombinant polypeptides representing the two forms (designated ABA-1A1 and ABA-1B1) showed similar binding affinities for a range of fluorescent active-site probes [retinol, dansylundecanoic acid, dansyl-DL-alpha-amino-octanoic acid, cis-parinaric acid (cPnA)] and for the non-specific hydrophobic surface probe 8-anilinonaphthalene-1-sulphonic acid. However, the molecular environments in the active sites are markedly different, as indicated by disparate fluorescence emission peaks and intensities of bound probes. CD showed that the proteins have similar secondary structures but differ in susceptibility to chemical denaturation/unfolding by guanidinium chloride. Both retain a single conserved tryptophan residue in a characteristic non-polar environment, as revealed by extreme fluorescence blue shift. Thus the gross differences in sequence of the two proteins are not reflected in their ligand-binding specificities but in their binding-site environments.

Novel classes of fatty acid and retinol binding protein from nematodes

Parasitic nematodes have recently been found to produce proteins which represent two new classes of fatty acid and retinoid binding protein. The first is the nematode polyprotein allergens/antigens (NPAs) which, as their name suggests, are synthesised as large polyproteins which are subsequently cleaved at regularly spaced sites to form multiple copies of a fatty acid binding protein of approximately 14.5 kDa. Binding studies using molecular environment-sensitive fluorescent ligands have shown that the binding site is highly unusual, producing blue-shifting in fluorescence to an unprecedented degree, suggesting a remarkably non-polar environment and isolation from solvent water. Computer-based structural predictions and biophysical observations have identified the NPAs as highly helical proteins which might form a four helix bundle, so constitute a new class of lipid binding protein from animals. The second class, like the NPAs, binds both fatty acids and retinol, but with a higher affinity for the latter. These are also highly helical but are structurally distinct from the NPAs. The biological function of these new classes of protein are discussed in the context of both the metabolic requirements of the parasites and the possible role of the proteins in control of the immune and inflammatory environment of the tissue sites parasitised.

The Ov20 protein of the parasitic nematode Onchocerca volvulus. A structurally novel class of small helix-rich retinol-binding proteins

Ov20 is a major antigen of the parasitic nematode Onchocerca volvulus, the causative agent of river blindness in humans, and the protein is secreted into the tissue occupied by the parasite. DNA encoding Ov20 was isolated, and the protein was expressed in Escherichia coli. Fluorescence-based ligand binding assays show that the protein contains a high affinity binding site for retinol, fluorescent fatty acids (11-((5-dimethylaminonaphthalene-1-sulfonyl)amino)undecanoic acid, dansyl-DL-alpha-aminocaprylic acid, and parinaric acid) and, by competition, oleic and arachidonic acids, but not cholesterol. The fluorescence emission of dansylated fatty acids is significantly blue-shifted upon binding in comparison to similarly sized beta-sheet-rich mammalian retinol- and fatty acid-binding proteins. Secondary structure prediction algorithms indicate that a alpha-helix predominates in Ov20, possibly in a coiled coil motif, with no evidence of beta structures, and this was confirmed by circular dichroism. The protein is highly stable in solution, requiring temperatures in excess of 90 degrees C or high denaturant concentrations for unfolding. Ov20 therefore represents a novel class of small retinol-binding protein, which appears to be confined to nematodes. The retinol binding activity of Ov20 could possibly contribute to the eye defects associated with onchocerciasis and, because there is no counterpart in mammals, represents a strategic target for chemotherapy.

Effect of pH on in vitro antimicrobial susceptibility of the Bacteroides fragilis group

We studied the effect of pH (7.1, 6.3, and 5.8) on the in vitro susceptibilities of 59 isolates of Bacteroides fragilis and 60 isolates of other B. fragilis group species to trovafloxacin, ciprofloxacin, clindamycin, ampicillin-sulbactam, piperacillin-tazobactam, imipenem, and meropenem. For each agent tested the geometric mean MIC was highest at pH 5.8, intermediate at pH 6.3, and lowest at pH 7.1. The magnitude of the pH effect varied greatly among different antibiotics. These data show that an acidic pH decreases the in vitro susceptibilities of the B. fragilis group to several antibiotics.

Analysis of trends in antimicrobial resistance patterns among clinical isolates of Bacteroides fragilis group species from 1990 to 1994

Antimicrobial resistance, including plasmid-mediated resistance, among Bacteroides fragilis group species is well documented. A 5-year (1990-1994) prospective, eight-center survey of 3,177 clinical isolates of Bacteroides species was undertaken to review trends in resistance, using the breakpoints for full and intermediate susceptibility established by the National Committee for Clinical Laboratory Standards. No documented resistance to either metronidazole or chloramphenicol was found in this survey. Among B. fragilis isolates virtually no resistance was seen to imipenem, meropenem, ampicillin/sulbactam, piperacillin/tazobactam, or ticarcillin/clavulanate. Significant increases in resistance among B. fragilis isolates to cefotetan, ceftizoxime, and clindamycin (p < .01) were noted. Resistance to cefoxitin remained unchanged. Among the non-fragilis species of the B. fragilis group, there was virtually no resistance to imipenem, meropenem, chloramphenicol, or metronidazole. The three beta-lactamase inhibitors had increasing levels of resistance, although 95%-98% of strains were susceptible (p < .05). There was a significant decline in cefoxitin, cefmetazole, and clindamycin activity over time against these strains (p <.01). There was a significant (P < .001) increase in geometric mean minimum inhibitory concentration for most drugs and species tested from 1990 to 1994. Clusters in the eight institutions could not account for this rise in resistance. This survey demonstrates that rates of resistance of B. fragilis and non-fragilis species of B. fragilis group are increasing.

Correlation of various in vitro testing methods with clinical outcomes in patients with Bacteroides fragilis group infections treated with cefoxitin: a retrospective analysis

There is limited information regarding the correlation of anaerobic susceptibility testing and outcome in the treatment of Bacteroides fragilis infections. We retrospectively analyzed the clinical outcomes of B. fragilis infections in patients treated with cefoxitin; the analysis was blinded for susceptibility results. Isolates of B. fragilis were tested by multiple agar dilution methods, disk elution, and commercial broth microdilution methods. Of 19 patients analyzed, 11 were cured and 8 were treatment failures. No significant differences existed between the groups with respect to age, sex distribution, weight, APACHE II score, dose of cefoxitin, or bacteremia. Failure was associated with a longer cefoxitin dosing interval (P = 0.019), a longer duration of hospitalization (P = 0.038), and decreased duration of cefoxitin treatment (P = 0.05). Four agar dilution systems (brucella plus blood, Wilkins-Chalgren, Wilkins-Chalgren plus blood, brain heart infusion plus blood) and two broth systems (Wilkins-Chalgren microdilution and a commercial system [Micromedia; Beckman, Carlsbad, Calif.]) all demonstrated lower geometric mean MICs for isolates from the group of patients that could be cured. Only the commercial broth microdilution medium (Micromedia) demonstrated a significantly reduced geometric mean MIC (P = 0.056). By using a logistic regression analysis, the shorter cefoxitin dosing interval (P = 0.0004) and the lower geometric mean MIC (P = 0.0088) in the commercial broth microdilution system were shown to be independent predictors of treatment success. These data suggest that the time that the concentration of cefoxitin is over the MIC for B. fragilis may be an important predictor of treatment success.

Antimicrobial susceptibility patterns of the Bacteroides fragilis group in the United States, 1989

A national survey of Bacteroides fragilis group was continued in 1989 for the ninth consecutive year. Seven hundred thirty-nine isolates of B fragilis group from eight centers were tested for susceptibility to 14 antimicrobials. Sulbactam and clavulanic acid, beta-lactamase inhibitors, were tested at a constant concentration of 8 micrograms/ml and 2 micrograms/ml, respectively. Sulbactam was also tested in a fixed ratio of 1:2. Imipenem, ampicillin+sulbactam, and ticarcillin+clavulanic acid had resistance of less than 1% at breakpoints of 8 micrograms/ml, 16 micrograms/ml, and 64 micrograms/ml, respectively. At 32 micrograms/ml, resistance to cefoxitin, cefotetan, ceftizoxime, and ceftriaxone were 4%, 25%, 26%, and 46%, respectively. Clindamycin resistance was 10% at a breakpoint of 4 micrograms/ml. No isolates were resistant to chloramphenicol or metronidazole. Resistance for five B fragilis species to cefoxitin, ceftizoxime, and cefotetan varied greatly among both species and participating institutions. The addition of a beta-lactamase inhibitor increased the potency of the beta-lactam drugs tested as combinations. This finding suggests that beta-lactamase production is the major resistance factor in members of the B fragilis group.

Myosin isoenzyme distribution in overloaded human atrial tissue

Using nondenaturing polyacrylamide gel electrophoresis, we have identified two distinct myosin isoenzymes in human atrial tissue that correspond to the V1 and V3 isomyosins found in rat ventricular tissue. Normal left and right atrial appendages have approximately 50% V3. When the left atrium was exposed to hemodynamic overload secondary to mitral stenosis, the percent V3 increased to 77 +/- 10% (n = 10); exposure to hemodynamic overload secondary to mitral regurgitation caused an increase to 70 +/- 14% (n = 6). Changes in the isoenzyme pattern were seen in the right atria of patients with mitral stenosis and markedly elevated pulmonary arterial pressures compared with control subjects and patients with mitral stenosis without severe pulmonary hypertension. Several clinical variables were examined to determine which factors might influence isoenzyme expression. Age, sex, the presence of atrial fibrillation, and pulmonary capillary wedge pressure did not predict the isoenzyme pattern. However, patients with mitral valvular disease and only slightly enlarged left atria tended to have a higher percent V3 than those with massively enlarged atria. These data confirm that human atrial tissue, like rat ventricular tissue, can alter its isomyosin composition in response to a hemodynamic load. The data further suggest that the isoenzyme shift is an early adaptation to the imposed load.