Ethical Considerations and Fairness in the Use of Artificial Intelligence for Neuroradiology

In this review, concepts of algorithmic bias and fairness are defined qualitatively and mathematically. Illustrative examples are given of what can go wrong when unintended bias or unfairness in algorithmic development occurs. The importance of explainability, accountability, and transparency with respect to artificial intelligence algorithm development and clinical deployment is discussed. These are grounded in the concept of "primum no nocere" (first, do no harm). Steps to mitigate unfairness and bias in task definition, data collection, model definition, training, testing, deployment, and feedback are provided. Discussions on the implementation of fairness criteria that maximize benefit and minimize unfairness and harm to neuroradiology patients will be provided, including suggestions for neuroradiologists to consider as artificial intelligence algorithms gain acceptance into neuroradiology practice and become incorporated into routine clinical workflow.

Medial temporal lobe functional connectivity predicts stimulation-induced theta power

Focal electrical stimulation of the brain incites a cascade of neural activity that propagates from the stimulated region to both nearby and remote areas, offering the potential to control the activity of brain networks. Understanding how exogenous electrical signals perturb such networks in humans is key to its clinical translation. To investigate this, we applied electrical stimulation to subregions of the medial temporal lobe in 26 neurosurgical patients fitted with indwelling electrodes. Networks of low-frequency (5–13 Hz) spectral coherence predicted stimulation-evoked increases in theta (5–8 Hz) power, particularly when stimulation was applied in or adjacent to white matter. Stimulation tended to decrease power in the high-frequency broadband (HFB; 50–200 Hz) range, and these modulations were correlated with HFB-based networks in a subset of subjects. Our results demonstrate that functional connectivity is predictive of causal changes in the brain, capturing evoked activity across brain regions and frequency bands.

Direct electrical brain stimulation can induce widespread changes in neural activity, offering a means to modulate network-wide activity and treat disease. Here, the authors show that the low-frequency functional connectivity profile of a stimulation target predicts where induced theta activity occurs.

Development of Weather-Based Predictive Models for Fusarium Head Blight and Deoxynivalenol Accumulation for Spring Malting Barley

The associations between Fusarium head blight (FHB), caused by Gibberella zeae, and deoxynivalenol (DON) accumulation in spring malting barley (Hordeum vulgare) and hourly weather conditions predictive of DON accumulation were examined using data from six growing seasons in the U.S. Northern Great Plains. Three commonly grown cultivars were planted throughout the region, and FHB disease and DON concentration were recorded. Nine predictor variables were calculated using hourly temperature and relative humidity during the 10 days preceding full head spike emergence. Simple logistic regression models were developed using these predictor variables based on a binary threshold for DON of 0.5 mg/kg. Four of the nine models had sensitivity greater than 80%, and specificity of these models ranged from 67 to 84% (n = 150). The most useful predictor was the joint effect of average hourly temperature and a weighted duration of uninterrupted hours (h) with relative humidity greater than or equal to 90%. The results of this study confirm that FHB incidence is significantly associated with DON accumulation in the grain and that weather conditions prior to full head emergence could be used to accurately predict the risk of economically significant DON accumulation for spring malting barley.

Genotypic interaction and gender specificity of common genetic variants in the p53/mdm2 network in Crohn's disease

BACKGROUND/AIMS

Defective p53-mediated apoptosis and cell cycle control have been implicated in the immunopathogenesis of Crohn's disease (CD). Since common functional variants of p53 (SNP72 G/C) and its key negative regulator mdm2 (SNP309 T/G) have been reported to affect cellular apoptotic and cell cycle arrest capacities, we assessed the effects of these variants on CD susceptibility and their relationship to NOD2/CARD15 as a well-established genetic CD risk factor.

METHODS

The variants SNP72 G/C and SNP309 T/G were genotyped in 149 European CD patients and 478 healthy controls. Subgroup analysis was performed in relation to NOD2/CARD15 status and to demographic/clinical characteristics.

RESULTS

The p53 SNP72 CC genotype tended to be less frequent in CD. This reached statistical significance only in the male cohort (0 vs. 7.3%; p = 0.037). Genotype and allele frequencies of both single-nucleotide polymorphisms (SNPs) were otherwise not significantly different. In the combined genotypic analysis, the genotype p53 SNP72 CC was significantly underrepresented in mdm2 SNP309 TT homozygotes (0 vs. 9.7%; p = 0.034). No association was observed between NOD2/CARD15 and the respective SNPs.

CONCLUSION

We report on a gender-specific protective effect of the low-apoptotic SNP72 CC genotype, and a gender-unrestricted genotypic interaction between SNP309 TT and SNP72 CC, which, for the first time, links sequence variation of the p53/mdm2 network to CD, independent of NOD2/CARD15.

The del/del genotype of the nuclear factor-kappaB -94ATTG polymorphism and its relation to aggressive periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis is influenced by specific host-dependent immune responses. Periodontopathogens induce innate immune responses, amongst others, via toll-like receptor 2 (TLR2), resulting in activation of the nuclear transcription factor nuclear factor-kappaB (NF-kappaB). The aim of this case-control study was to evaluate links between genetic variants of these genes and chronic/aggressive periodontitis in a multivariate model.

MATERIAL AND METHODS

A total of 141 patients with periodontitis (63 with chronic periodontitis and 78 with aggressive periodontitis) and 81 controls without periodontitis were included in the study. Polymorphisms in TLR2 (Arg677Trp, Arg753Gln) and in NF-kappaB (-94ins/delATTG) were determined by restriction fragment length polymorphism and fragment length analyses, respectively. Subgingival bacterial colonization was evaluated using a PCR/DNA probe test (micro-Ident).

RESULTS

Although there was no association of the TLR2 polymorphism Arg753Gln with periodontitis, heterozygous carriers (Arg/Gln) were at a higher risk for colonization with bacteria of the 'red complex' (corrected p-value = 0.042). The del/del genotype of the NF-kappaB polymorphism was associated with aggressive periodontitis considering age, gender, smoking and approximal plaque index as potential confounders (odds ratio = 2.81, p = 0.035, 95% confidence interval: 1.08-7.33). del/del carriers had a higher risk for subgingival colonization with Aggregatibacter actinomycetemcomitans (odds ratio = 2.36, p = 0.030, 95% confidence interval: 1.09-5.1; adjusted for age, gender, smoking and pocket depth(bacteria)).

CONCLUSIONS

The del/del genotype of NF-kappaB was shown to be associated with the occurrence of aggressive periodontitis.

Mass effect in the thoracic spine from remnant bone wax: an MR imaging pitfall

Bone wax used in neurosurgical procedures is a rare cause of complications after surgery. We present a patient who developed paraplegia following thoracic spine surgery. A subsequent MR imaging study demonstrated a signal void that resembled postoperative air but appeared to cause cord compression and proved after a second surgery to represent bone wax. Recognizing the MR imaging and CT characteristics of bone wax is important to prevent mistaking it for residual air in postoperative imaging.

[Are there gender-related differences in the therapeutic management of patients suffering from inflammatory bowel disease? Subgroup analysis of a prospective multicentre online-based trial]

INTRODUCTION

The most frequently prescribed medications for patients suffering from inflammatory bowel disease (IBD) in the Rhein-Main region of Germany are aminosalicylates and corticosteroids irrespective of the disease activity. In contrast, immunomodulators only play a marginal role. As anti-TNF therapy is very costly, it is prescribed in outpatient services of hospitals rather than in gastroenterological practices.

AIM

The aim of this study was to evaluate possible gender-related differences in the therapeutic management of IBD patients treated in the Rhein-Main region of Germany.

METHODS

Data records about past medical history, disease status, laboratory values and medical treatment of outpatients of 10 gastroenterological practices and 3 hospitals were collected from November 1st 2005 to July 31st 2007 and analysed with regard to gender-related differences in therapy and disease management.

RESULTS

Overall, no statistically significant difference in gender-specific medical treatment could be observed in the study cohort. However, detailed analyses revealed, that 1. women suffering from IBD, who are treated in outpatient services of hospitals, are more often under immunosuppressants, irrespective of disease activity, 2. in gastroenterological practices less than 3 % of patients are prescribed any immunosuppressive therapy (vs. 17 % [men] und 42 % [women] in hospital outpatient services), and 3. anti-TNF therapy is applied more frequently in men as compared to women in hospital outpatient services in both remission and active disease.

CONCLUSION

This study discloses the gender-specific differences in the therapeutic management of IBD patients in a congested urban area in Germany. Further studies are required to confirm the tendencies detected.

Fusarium head blight severity and deoxynivalenol concentration in wheat in response to Gibberella zeae inoculum concentration

The relationship between inoculum dose and resulting disease levels and deoxynivalenol (DON) accumulation in the Fusarium head blight (FHB) of wheat pathosystem was examined under controlled conditions. Greenhouse-grown spring wheat plants were inoculated at flowering with suspensions that varied in Gibberella zeae macroconidia concentration. The spikes were bagged for 72 h to promote infection and plants were then kept under ambient greenhouse conditions and disease allowed to develop. Spikes were rated at 15 days after inoculation for disease incidence and severity, removed from the greenhouse, and dried. DON concentration was determined in grain-only and whole-spike samples for each inoculation treatment. Regression analysis was used to evaluate the mathematical relationship between inoculum dose and the (i) disease metrics or (ii) DON concentration. Both disease incidence and severity were found to increase sharply in relation to inoculum concentration until an asymptote was reached. In both instances, a negative exponential function was found to best explain this relationship. By contrast, DON concentration in both grain-only and whole-spike tissues increased with additional inoculum. These relationships were best explained with linear functions for both sample types, although DON accumulation increased at a greater rate in whole-spike tissue. The functions were evaluated further using data collected from unrelated field studies and, although not particularly consistent, provided reasonably accurate predictions in growing seasons when the environment was only moderately favorable for FHB.

Family-based mapping of quantitative trait loci in plant breeding populations with resistance to Fusarium head blight in wheat as an illustration

Traditional quantitative trait loci (QTL) mapping approaches are typically based on early or advanced generation analysis of bi-parental populations. A limitation associated with this methodology is the fact that mapping populations rarely give rise to new cultivars. Additionally, markers linked to the QTL of interest are often not immediately available for use in breeding and they may not be useful within diverse genetic backgrounds. Use of breeding populations for simultaneous QTL mapping, marker validation, marker assisted selection (MAS), and cultivar release has recently caught the attention of plant breeders to circumvent the weaknesses of conventional QTL mapping. The first objective of this study was to test the feasibility of using family-pedigree based QTL mapping techniques generally used with humans and animals within plant breeding populations (PBPs). The second objective was to evaluate two methods (linkage and association) to detect marker-QTL associations. The techniques described in this study were applied to map the well characterized QTL, Fhb1 for Fusarium head blight resistance in wheat (Triticum aestivum L.). The experimental populations consisted of 82 families and 793 individuals. The QTL was mapped using both linkage (variance component and pedigree-wide regression) and association (using quantitative transmission disequilibrium test, QTDT) approaches developed for extended family-pedigrees. Each approach successfully identified the known QTL location with a high probability value. Markers linked to the QTL explained 40-50% of the phenotypic variation. These results show the usefulness of a human genetics approach to detect QTL in PBPs and subsequent use in MAS.

[Nutritional factors and nutritional therapy for irritable bowel syndrome--what is worthwhile?]

The prevalence of irritable bowel syndrome (IBS) has increased over the last 50 years in countries where a Western-style diet has been prominent or introduced and 20 - 65 % of patients with irritable bowel syndrome (IBS) attribute their symptoms to something in food that activates an abnormal response. However, data from dietary elimination and re-challenge studies are inconclusive. Although investigations have shown that bran may be helpful in some patients, a complete review of the literature does not reveal conclusive evidence that a high fibre diet therapy is effective in IBS. From the limited reports on probiotics, there appears to be a trend to decreasing symptoms. Despite numerous reviews on this subject, it is very difficult to give general dietary advice to IBS patients, but dietary experts may have a positive role in managing such patients. It is clear that much more prospective research is needed to study both dietary factors and probiotics in these areas.

Distribution and Recovery of Tilletia indica Teliospores from Regulated Wheat Fields in Texas

Eight wheat fields from the Karnal bunt-regulated regions within Texas were grid sampled to gain a better understanding of the ecology and epidemiology of teliospores produced by the causal agent, Tilletia indica. Teliospores from 25-g aliquots of soil from each grid point were extracted using a size-selective sieving sucrose-centrifugation procedure. Teliospores were recovered from all eight fields and, in some cases, from every grid point within a field. Total teliospore numbers ranged from 0 to 1,305 per 25 g of soil. Over 70% of the total grid sampled points contained one or more teliospores. The relation between soil chemical and physical characteristics and teliospore numbers from each field was evaluated. In general, no consistent, significant trend could be made between soil factors and teliospore numbers. Geostatistics were used to analyze data from grid points and create contour maps. Teliospore distribution was aggregated in four of the fields, random in three of the fields, and discontinuous (neither random nor aggregated) in a single field. This is the first report of widespread distribution and high teliospore numbers from wheat field soils in the United States.

[Bacterial overgrowth syndrome]

Small bowel bacterial overgrowth is a syndrome caused by an abnormal number of bacteria in the upper part of the small bowel and associated with a complex array of clinical symptoms, i. e., chronic diarrhoea, steatorrhoea, macrocytic anaemia, weight loss, and less commonly, protein-losing enteropathy. The most common underlying factors are small intestinal stagnation or dysmotility, intestinal obstruction, blind or afferent loops, and decreased gastric secretion. The treatment usually consists in the eradication of bacterial overgrowth with repeated courses of antimicrobials, correction of associated nutritional deficiencies and, when possible, correction of the underlying predisposing conditions.

Epidemiology of Tilletia indica Teliospores in Regulated Wheat Fields in Texas

To examine the epidemiology of Tilletia indica teliospores in naturally infested soils from wheat fields in both Karnal bunt-regulated regions in Texas, soil was grid sampled from fields that were bunted-kernel positive for Karnal bunt in 1997, 2001, both years, or never. Aliquots of soil from each point were pooled, and teliospores were extracted using a size-selective sieving-sucrose centrifugation method. Teliospores were enumerated microscopically, and low quantities (< 8 per 25 g of soil) were identified in 14 of 15 fields sampled from the regulated regions of Texas, including fields that have never tested positive for bunted kernels, indicating a widespread distribution. No teliospores were isolated from the single field examined outside of the regulated regions. The percent clay was significantly, negatively correlated with the baseline teliospore number and the estimated (extrapolated) number of teliospores per sample, indicating a potential impact of soil composition on teliospore survival. The latter factor was also significantly, positively correlated to the number of times a field had tested positive.

The Generation and Quantification of Resistance to Dimethomorph in Phytophthora infestans

The generation of dimethomorph resistance in Phytophthora infestans was attempted using ethidium bromide/UV light mutagenesis and repeated culturing on dimethomorph-amended medium. Ethidium bromide/UV mutagenesis created two isolates of P. infestans with resistance factors for dimethomorph >20, i.e., the ratio of the 50% effective concentration (EC₅₀) of the mutant to that of the wild-type. With repeated culturing on dimethomorph-amended medium, the rate of growth (mm diameter/day) increased until the tenth subculture for most P. infestans isolates. Resistance factors generated from repeated culturing were <8 for all isolates. For most isolates, the generation of dimethomorph resistance resulted in reduced growth rates on nonamended medium, regardless of the level of resistance or induction treatment. Additionally, the frequency of infection of leaf disks and whole tubers was significantly reduced in >20% of the isolates repeatedly subcultured on dimethomorph-amended medium. Regardless of the induction treatment, reduced fitness was common for all P. infestans isolates, indicating a potential biological cost associated with dimethomorph resistance. Based on these results, the development of field resistance to dimethomorph in P. infestans is unlikely with the currently employed resistance management strategies.

Variations in the Sensitivity of Phytophthora infestans Isolates from Different Genetic Backgrounds to Dimethomorph

The sensitivities of 11 isolates of Phytophthora infestans to dimethomorph were examined at all stages of the asexual life cycle and when inoculated onto potato leaf discs. In vitro zoospore encystment and cyst germination were highly sensitive to dimethomorph with 50% reduction of mycelial growth and cyst germination (EC₅₀) values for most isolates <0.20 μg/ml, whereas direct sporangia germination and in vitro hyphal growth and sporulation were less sensitive (means of 0.45 and 0.22 μg/ml, respectively). Zoosporogenesis was not significantly inhibited at the maximum dimethomorph concentration examined, 10 μg/ml. Significant differences (Fisher's least significant difference, P = 0.05) in the EC₅₀ values were present between isolates for all stages of the asexual life cycle, except direct sporangia germination and zoosporogenesis. Sensitivity ratios between the least- and most-sensitive isolates were 6.11, 12.14, 12.36, and 10.56 for hyphal growth, in vitro sporulation, zoospore encystment, and cyst germination, respectively. Application of dimethomorph at 1,000 μg/ml to potato leaf discs at 24 or 48 h before inoculation completely inhibited symptom incidence for most isolates, whereas application after inoculation generally was not significantly different from the untreated control, regardless of concentration. Sporulation from leaf discs treated with dimethomorph at 24 or 48 h after inoculation was completely inhibited for all isolates with dimethomorph at 1,000 μg/ml, even when symptom incidence was not significantly reduced.

Effect of Host Plant Resistance and Reduced Rates and Frequencies of Fungicide Application to Control Potato Late Blight

Field experiments were conducted during 1998 to 2000 to determine the response of commercial potato cultivars and advanced breeding lines (ABL) differing in susceptibility to foliar late blight (caused by Phytophthora infestans) to reduced rates and frequencies of residual, contact fungicide applications. When environmental conditions were most favorable for the development of late blight, the lowest application rate of the fungicides chlorothalonil or fluazinam (33% of the manufacturers' recommended application rate [MRAR]) gave unsatisfactory control of potato late blight. Under conditions moderately conducive for late blight development, effective control was achieved with 33 to 66% MRAR with either fungicide. The Michigan State University advanced selection, MSG274-3, was the least susceptible ABL tested and, during 1998 to 2000, late blight was effectively managed using reduced rates of fungicides. Application rates of chlorothalonil (33 to 100% MRAR) significantly reduced late blight in the cultivar Snowden (5-day application interval) compared with the nontreated control; whereas, late blight was not effectively controlled in Snowden even at 100% MRAR of chlorothalonil at either 10- or 15-day application intervals in 1999 or 2000. The ABL MSG274-3 was the least susceptible of all cultivars and ABL used in this study, and required minimal chemical protection against late blight. The study demonstrates that ABL with reduced susceptibility to late blight can be managed with reduced fungicide rates and longer application intervals, thus offering more economical control of this disease.

Effect of mechanical reinforcement on stability of the rotary door flap laryngotracheal reconstruction: a canine study

OBJECTIVE/HYPOTHESIS

The rotary door flap (RDF) laryngotracheal reconstructive procedure uses a 180 degrees rotation of the sternohyoid muscle into a laryngofissure. Despite excellent clinical results, there are concerns of flap inspiratory prolapse. This study examined RDF stability and the efficacy of ancillary materials in providing additional support.

METHODS

Seventeen dogs underwent endoscopic induction of subglottic stenosis and delayed RDF reconstruction. Animals received 1) traditional RDF (control), 2) RDF with titanium screen implant, 3) RDF with porous polyethylene implant, or 4) RDF with hydroxyapatite cement (HAC) injection. Four weeks postoperatively the flaps were tested for stability. On qualitative assessment, endoscopic visualization was completed with quiet respiration and then following endotracheal tube occlusion. On quantitative assessment, after animals were killed, the RDF segment was isolated and subjected to negative pressure (maximum pressure, -50 mm Hg). The pressure-causing collapse was measured.

RESULTS

In the traditional RDF animals (control), five of six flaps were stable in vivo and with negative pressures. In the titanium screen, porous polyethylene group, and HAC groups, respectively, four of four, three of four, and two of three flaps were stable in vivo and under negative pressure. Flaps that demonstrated instability had granulation, dehiscence, and poor healing. These occurred in 1 of 6 animals in the traditional RDF group and in 2 of 11 animals in the implant groups. In addition, 13 of 24 animals assigned to the implant groups died, compared with 2 of 8 of those in the traditional RDF group.

CONCLUSIONS

The RDF is stable and maintains the airway under physiological conditions. Support materials did not improve stability, render flap harvest more difficult, or increase morbidity and mortality.

Structural stability of the rotary door myocutaneous flap

This canine study examines the structural stability of extensive laryngotracheal reconstruction with the sternohyoid myocutaneous rotary door flap (RDF) and modifications of the RDF with subdermal collagen and collagen hydroxyapatite matrix. The postreconstruction stability of the RDF and these modifications were tested and compared by measuring immediate postmortem airway stability during application of negative intraluminal pressures. Comparisons between controls and experimental specimens demonstrated that the RDF provides structural stability to secure airway patency under physiologic pressures. Biocompatible matrix adds further structural support in maintenance of the reconstructed lumen. This study validates that the RDF provides adequate rigid support for extensive laryngotracheal reconstruction without the requirement of skeletal support.

Transnasal transseptal endoscopic approach to the sphenoid sinus

A modified transseptal approach to the sphenoid sinus and pituitary gland utilizing rigid endoscopy has been developed by the Departments of Otolaryngology, Plastic Surgery, and Neurosurgery at The Cleveland Clinic Foundation. When compared with alternate approaches or the nonendoscopic transseptal procedure, the modified approach provides better visualization and increased illumination of the surgical sites. Other advantages include a decrease in operating time, dissection, bleeding, and postoperative morbidity without compromising nasal function in the postoperative period.

Endoscopic approach for benign tumor ablation of the forehead and brow

Resection of benign tumors of the forehead and brow raises aesthetic concerns. An endoscopic subperiosteal approach to benign bony and soft-tissue tumors in the supraorbital and frontotemporal regions permits extirpation of these masses without producing visible facial scars. Therefore, this technique was used for tumor resection in 4 patients. This procedure demonstrated magnified visualization of the masses, and safe access for excisional biopsy and bony contouring. In addition to more acceptable surgical scars, patients experienced no significant postoperative morbidity and a reduced incidence of swelling, discomfort, and scalp anesthesia. Therefore, we conclude that the endoscopic subperiosteal approach is a favorable alternative for resection of suitable tumors.

The relationship of the guided gingival frame to the provisional crown for a single-implant restoration

This article discusses and defines the use of the provisional crown to encourage gingival growth to provide an ideal frame for a single-tooth implant prosthesis. Both the rationale and the technique are presented. The successful use of an osseointegrated implant to support a fixed prosthesis is an accepted treatment modality in both the biologic and clinical dental communities. The clinical examination, the radiographic survey, and diagnostic casts all contribute to achieving an optimal esthetic result, but the final image may continue to be elusive until the healing of the second-stage surgery when the gingiva can be evaluated. The gold standard of success is providing an inconspicuous result.

Tumor reactivity of immune T cells in short-term culture

The adoptive transfer of immune T cells is capable of mediating the regression of established neoplasms in a variety of animal tumor models. The antitumor activity is invariably proportional to the number of cells transferred, thus methods to expand immune cell number while maintaining therapeutic efficacy have been extensively investigated. Here we demonstrate that a short-term culture of immune T cells can amplify the T cell number and enhance the therapeutic reactivity against established pulmonary tumor, while maintaining immunological specificity. In contrast, the therapeutic reactivity of immune T cells against established subcutaneous tumor is diminished by short-term culture. While cultured immune T cells are not cytotoxic in a 4-h Cr-release assay, they do specifically secrete interferon gamma upon stimulation with tumor cells. T cells cultured after a single exposure to tumor are even more active against pulmonary tumor than T cells cultured from mice immunized repeatedly. This culture system can rapidly induce T cell proliferation and differentiation into mature effector cells, and the resulting cells demonstrate an enhanced ability to treat visceral metastases, but a decreased ability to treat subcutaneous tumor. Thus T cells cultured after a single exposure to tumor represent an ideal population of cells for use in human adoptive immunotherapy trials.

A comparative study of the microbiologic effectiveness of chemical disinfectants and peroxide-neutralizer systems

We evaluated the antimicrobial activity of chemical and hydrogen peroxide-neutralizer contact lens disinfection systems. The acute activity, storage, and recontamination potential of the two disinfection methods were compared by challenging the disinfectants with Staphylococcus spp., Pseudomonas aeruginosa, Serratia marcescens, Candida spp., and Aspergillus fumigatus. Chemical disinfectants preserved with polyquaternium-1 and polyhexamethylene biguanide and hydrogen peroxide-neutralizer systems with no additional preservatives were tested. Additionally, lens cases from patients using both systems were evaluated. Lens cases from patients using peroxide-neutralizer systems tended toward heavier contamination (31.8%) than the cases disinfected with a chemical system (20.3%, P = 0.16). The laboratory results showed that the differences in activity of chemical and peroxide-neutralizer systems was not statistically significant at the disinfection times against Staphylococcus epidermidis, S. marcescens, Candida parapsilosis, and A. fumigatus (P = 0.1037 to P = 0.5412). A statistical difference was shown against C. albicans (P = 0.0176) in favor of the peroxide-neutralizer systems. The reverse was true during storage. Although the chemical disinfectants maintained the population of microorganisms, the bacteria and yeast increased to over 10(7) CFU/mL in neutralized peroxide systems. Overall, the results emphasize the importance of contact lens products containing preservatives for lasting protection from microorganisms.

Compliance: a comparison of three lens care systems

Noncompliance is an important health care issue. This report presents results of assessments of three different lens care systems and directly compares compliance with each and the potential impact on patients' safety and comfort. Methods involved trained interviewers, patient demonstrations, a panel of experts, statistical analyses, and an assessment of the clinical significance of patients' noncompliant behaviors. These methods were able to discriminate among the levels of compliance with the lens care systems assessed. The three regimens were comparable regarding steps significant to lens wearing comfort with approximately one-third of all patients noncompliant with at least one of these steps. The same cannot be said regarding safety, however, with the incidence of noncompliance at 55, 84, and 91% for the three regimens. These findings indicate that simplicity alone cannot overcome noncompliance and the design of the system is an important consideration when making recommendations regarding lens care.

Compliance and contact lens care: a new assessment method

We propose a new method for assessing and quantifying compliance with contact lens care regimens. We recommend two separate procedures: one in which trained interviewers examine the actual lens care techniques used by typical, experienced patients and another in which clinicians rate each step in a lens care regimen as to the level of risk to the patient's comfort and safety if noncompliance with that step occurs. When combined, these steps quantify compliance with the regimen under investigation. The method can be used to assess the incidence of compliance with the regimen in question, and to compare compliance across dissimilar care systems. In our investigation, we applied the method to a multi-purpose solution regimen which has been marketed as being simple to use and, therefore, the correct care procedures are more likely to be complied with. However, we found that patient compliance with this regimen was equivalent to that found in an earlier study of an oxidative (hydrogen peroxide) care system, with noncompliance posing significant risks to both safety and comfort. The results indicate that 91% of patients were noncompliant with one or more of the steps in the lens care regimen that were judged to be clinically significant safety risk factors. Factors which posed significant risks to comfort were less likely to induce noncompliance. Only 34% of patients failed to follow one or more of the steps judged to provide clinically significant risks to comfort. The authors conclude that multi-purpose or simplified regimens are not acceptable substitutes for careful patient training and frequent follow-up.

A new method to assess contact lens care compliance

Failure to comply with contact lens care instructions is a conspicuous finding among both symptomatic and asymptomatic patients. We used a new methodology to quantify the extent of noncompliance and its clinical significance among 170 soft lens wearers. All patients were interviewed and asked to demonstrate their lens care practices. The significance of deviations from package insert instructions was assessed by 22 ophthalmologists and optometrists with regard to potential impact on safety and comfort. Virtually all patients were noncompliant with at least one required procedure. Noncompliant behavior that could significantly affect safety was more common and judged by practitioners to be of more concern than deviations that could affect comfort. Fifty-seven percent of the patients used disinfection procedures that could seriously affect safety. Overall, the study methodology was found to be very effective both for quantifying noncompliance and for evaluating its clinical significance.

Exercise tolerance in panic disorder patients

Sixteen panic patients and fifteen normal controls performed submaximal exercise testing on a bicycle ergometer. Only one patient subject panicked. Biochemical, physiological, and psychological data showed similar exercise tolerance in both patients and controls. Exercise-induced distress and lactate increment do not appear to cause panic attacks.

An acetylation method for the quantification of membrane lipids, including phospholipids, polyphosphoinositides and cholesterol

A method for the quantification of membrane lipids by acetylation with [3H]acetic anhydride is described. A standard lipid, labelled with 14C or 32P, is added to the sample and is simultaneously acetylated. The 3H/14C or 3H/32P ratios obtained in the acetylated lipids are proportional to the initial lipid concentration. The method has been used to quantify cholesterol, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in amounts between 2 and 10 nmol.

Ectocytosis caused by sublytic autologous complement attack on human neutrophils. The sorting of endogenous plasma-membrane proteins and lipids into shed vesicles

During sublytic complement attack on human neutrophils, plasma-membrane vesicles are shed from the cell surface as a cell-protection mechanism. By using surface-iodinated neutrophils it was found that less than 2% of surface label was recovered in shed vesicles under conditions where 40% of complement component C9 was shed. SDS/PAGE of 125I-labelled shed vesicles and plasma membranes showed differences in iodination pattern, demonstrating the sorting of membrane proteins into the shed vesicles. Analysis of 32P-labelled phospholipids after labeling of neutrophils with [32P]Pi before sublytic complement attack showed the presence of phosphatidic acid, phosphatidylcholine, phosphatidyl-ethanolamine, phosphatidylinositol and polyphosphoinositides in shed vesicles. Quantitative analysis using [3H]acetic anhydride-labelling method showed that the molar proportions of phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and sphingomyelin were the same in shed vesicles as in plasma membranes. In contrast, the molar proportions of cholesterol and diacylglycerol relative to sphingomyelin were almost twice those found in plasma membranes. The data demonstrate the existence of protein and lipid sorting mechanisms during the formation of shed vesicles when neutrophils are subject to sublytic complement attack. The term 'ectocytosis' is proposed to describe triggered shedding of right-side-out membrane vesicles from the surface of eukaryotic cells.

[Functional prosthetic treatment for the partially edentulous with osseointegrated implants]

The edentulous distal extension area has generally been restored with a removable partial denture. Some clinicians report long term success with a fixed partial denture containing distal cantilever pontic(s). Conversely, other clinicians find that the aforementioned is suspect at best due to the unusual stress demands placed on the abutment teeth by the pontic(s). When a tooth borne fixed partial denture is used to restore a long edentulous span, reports vary relative to long term success. The advent of osseointegrated implants as tooth substitutes may reduce and often eliminate particular compromised fixed or removable partial denture designs. Disregarding other problems that may or may not coexist with any remaining natural teeth in the same arch is a fallacious overview. It is paramount that future problems must be incorporated in any and all treatment plans at the same time the initial plan is formulated. Recent surveys reveal that a fewer percent of the population are becoming completely edentulous. Therefore, it is apparent that an increase in the treatment of the partially edentulous implant patient is a realistic consideration for all restorative dentists. However, it is ironic that those patients with the most severely debilitated conditions may often not be candidates for implant procedures. It is mandatory that a detailed explanation of any compromises and drawbacks to the final result must accompany the initial diagnostic presentation to the patient. It is quite evident that the dentist is confronted with a paradox that is difficult to resolve.(ABSTRACT TRUNCATED AT 250 WORDS)

Activity of cyclosporin A and a non-immunosuppressive cyclosporin against multidrug resistant leukemic cell lines

Cyclosporin A (CsA) has been shown to increase the sensitivity of multidrug resistant (MDR) cells to chemotherapeutic agents. Although the concentration of drug required to produce this effect is clinically achievable, the use of this drug would be hampered by significant immunosuppression. We report a comparison of the effects of 11-methyl-leucine cyclosporin (11-met-leu CsA), a non-immunosuppressive homolog to the parent drug, on MDR cell lines. Both cyclosporins sensitized resistant cell lines to doxorubicin, including P388 murine leukemia and GM 3639 human T-cell leukemia. The action of the cyclosporins was more pronounced with resistant cells than with sensitive ones. 11-Met-leu CsA was less potent than, but equally effective as, the parent drug. Both agents increased the intracellular accumulation and retention of doxorubicin in MDR cells. The sensitization caused by the cyclosporins was independent of their effects on cyclophilin, calmodulin, and protein kinase C. Furthermore, there were no differences in the binding of labelled CsA to MDR cells compared to the binding to sensitive cells, suggesting that P-glycoprotein was also not the molecular site of action. These studies demonstrate that a non-immunosuppressive cyclosporin can modulate multidrug resistance and suggest its further evaluation for use in clinical trials.

Opti-Free chemical disinfectant: a safety study with various soft contact lenses

A 6-month, Phase I clinical study evaluated Opti-Free, a new polyquaternium-1 chemical disinfectant intended for use with all types of soft contact lenses. Fifty-one patients were enrolled and divided into two groups. Group A used the product under exaggerated conditions, with daily exposure of Durasoft 3 (55%) and Hydrocurve II (55%) medium water content, ionic lenses to 5 mL of Opti-Free for 16 hours. Beginning on day 15, group A patients began a normal daily use schedule. Patients in group B wore CSI (38%), Permalens (71%), and Softcon (55%) contact lenses and used the regimen under normal daily use conditions throughout the study. The result indicate that Opti-Free is safe and effective under both normal and exaggerated use conditions. The implications of these data for patient safety are discussed.

The use of the bone curet in debridement of the burn wound and graft recipient sites

We describe the use of the simple bone curet for the purpose of scraping and debriding partial-thickness burn wounds and other chronic wounds encountered by the burn surgeon before autograft placement. In our experience the instrument allows more efficient and safer operating room debridement than does the standard scalpel blade.

Burns in substance abusers and in neurologically and mentally impaired patients

Drug and alcohol abusers, psychiatric patients, and those with neurologic dysfunction represent a large proportion of burn victims, but little is known about the impact of these conditions on burn morbidity. We wanted to determine whether this group has more complications, more surgical procedures, and longer hospital stays than other burn patients. We also wanted to find out if it cost more to care for these patients. A retrospective study of 180 patients admitted from January 1, 1986, to September 1, 1986, revealed that 51 (28%) of our patients had one or more of these impairments. The impaired and control groups were similar in the size of burn and the proportion of third-degree burns. The impaired group was much more likely to have flame burns and was somewhat older. The impaired patients stayed in the hospital nearly twice as long, had 60% more operations, and were twice as likely to have complications. No difference was seen in the frequency of death.

[Death in utero of a twin during the 2d and 3d trimester of pregnancy]

The study of a series of 9 cases of monofetal death during the last trimester of a twin pregnancy, permits to emphasize the relative frequency of this accident (7.14% in our series, markedly higher than those noted in the literature). An early diagnosis, essentially on ultrasonography, of monofetal death, enables monitoring of the mother and the surviving fetus for whom there is a non negligible risk. It is often necessary to deliver this fetus as soon as it is mature. Systematic and repeated clinical and ultrasonographic monitoring of any twin pregnancy during the third trimester ensures, in a large number of cases, prophylaxis of this accident.

Central serotonergic influences on renal electrolyte and water excretion

These studies examined the effects of altered activity or levels of serotonin (5-HT) in the central nervous system (CNS) on renal water and excretion of electrolytes and on arterial blood pressure. Rats were implanted with intracerebroventricular cannulae and then continuously hydrated with a hypotonic solution in order to induce a diuresis. In two separate experimental series, samples of urine were collected before and after intraventricular (i.v.t.) administrations of drug, and the effects on the excretion of sodium were determined. In the first experimental series, 5-HT in the CNS was manipulated by intraventricular administration of p-chloroamphetamine (PCA), an agent known to increase synaptic concentrations of 5-HT. Significant increases in urinary excretion of sodium (UNa V) and the Na/K ratio were observed after the administration of p-chloroamphetamine (200-600 micrograms i.v.t.). p-Chloroamphetamine in large doses also increased blood pressure and antidiuresis. The natriuresis, but not the pressor or antidiuretic responses, were attenuated by pretreatment with either p-chlorophenylalanine, an inhibitor of tryptophan hydroxylase, or fluoxetine, a drug which inhibits the release of 5-HT following the administration of p-chloroamphetamine. Thus, the natriuretic response appeared to be due to a p-chloroamphetamine produced increase of synaptic 5-HT. A further test of the role of 5-HT in the central control of sodium excretion was made in a second experimental series where hydrated rats received intraventricular injections of 5-HT. After direct application of 5-HT to the CNS, significant increases in UNa V and in the Na/K ratio were observed, concomitant with depressor effects.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of sodium periodate treatment on the modulation of the sodium pump in low-potassium type (LK) sheep red cells by the L antigen

1. The action of sodium periodate and neuraminidase on active and passive K+ transport in low-potassium type (LK) sheep red cells was investigated in relation to the contribution of the Lp and Ll antigens. 2. Active K+ transport in LK sheep red cells was not affected by treatment with sodium periodate (2 mM), or with neuraminidase. 3. Passive K+ transport in LK sheep red cells was increased by sodium periodate treatment in a concentration-dependent manner. The increase was not Cl- dependent, and so differed from the increased passive K+ uptake resulting from N-ethylmaleimide treatment. 4. HK sheep red cells treated with sodium periodate showed small increases in passive K+ uptake, and N-ethylmaleimide treatment used sequentially with sodium periodate resulted in further small increases in passive K+ uptake. 5. In LK sheep red cells the stimulation of active K+ transport by anti-L was impaired by 50% in cells treated with sodium periodate (2 mM) and was slightly lowered in cells treated with neuraminidase. 6. In LK sheep red cells inhibition of passive K+ transport by anti-L was not impaired by sodium periodate treatment (2 mM), or by neuraminidase treatment.

Inhibition of protein kinase C by antineoplastic agents: implications for drug resistance

One mechanism by which drugs alter the function of enzymes is through chronic inhibition. To determine whether commonly used cancer chemotherapeutic agents could alter protein kinase C (PKC) and thereby modify the calcium-messenger system, we studied the effect of anthracyclines and vinca alkaloids on the activity of PKC. Doxorubicin, daunomycin, vincristine and vinblastine inhibited the activity of PKC by 50% at concentrations of 150, 120, 350 and 140 microM respectively. Furthermore, we demonstrated the potential for this interaction to occur in intact cells, since doxorubicin blocked the binding of the phorbol ester, PDBu, to its receptor, PKC. The mode of inhibition of PKC was due, at least in part, to interference with the activation of the enzyme by phosphatidylserine. The activity of PKC was increased 15 fold in a highly resistant human breast cancer line, but this increase in enzymic activity was not seen in all lines tested. These studies demonstrate that anthracyclines and vinca alkaloids inhibit PKC, and suggest that chronic antagonism could lead to changes in its activity and function.

Inhibition of human purine nucleoside phosphorylase by acyclic nucleosides and nucleotides

In an effort to develop more potent inhibitors of human purine nucleoside phosphorylase (PNP) as immunosuppressive and cancer chemotherapeutic agents, the affinity of the erythrocytic enzyme for 30 acyclic nucleosides, nucleotides and related compounds was determined. Among the acyclonucleosides, 2'-nordeoxyguanosine [2'NDG, 9-(1,3-dihydroxy-2-propoxymethyl)guanine] had a 3-fold greater affinity than acyclovir, and 8-amino-2'NDG was the best inhibitor with Ki = 2.6 X 10(-7) M. The ether moiety of the acyclovir and 2'NDG side-chains was not important for binding. Phosphorylated 2'NDG analogs appeared to act as multisubstrate analogs with optimal binding at low (1 mM) phosphate concentration. The 2'NDG mono- and triphosphates had higher affinities than those reported for the phosphorylated acyclovir derivatives but the diphosphate had a similar Ki value of 9 X 10(-9) M. Poor affinity, independent of phosphate concentration, was found for 9-(2-phosphonoethyl)guanine. The 3'-phosphate derivative of 8-(3-hydroxypropyl)-9-methylguanine inhibited with a Ki = 2 X 10(-5) M in 1 mM phosphate. The chemical syntheses of new analogs are described.

L-antigen and active potassium transport in HK and LK red cells of Barbary sheep (Ammotragus lervia)

1. The potassium concentration in red cells of 21 Barbary sheep showed a bimodal distribution, with five animals of LK type (K+ conc. 30-45 mM) and 16 of HK type (K+ conc. 80-95 mM). 2. Evidence is presented that both Lp and Ll antigens are present on LK Barbary sheep red cells. 3. Active K+ transport in LK Barbary sheep red cells was stimulated 3-5 fold by sheep and goat anti-L. 4. Active K+ transport in HK Barbary sheep red cells was higher than in LK red cells. Five out of six HK animals tested showed no stimulation of active K+ transport with anti-L. One HK animal (2BA2) showed some stimulation of active K+ transport, and also absorbed some anti-L from antisera, suggesting that Lp antigen is present on these red cells. 5. Ouabain-sensitive ATPase in membranes from HK and LK Barbary sheep red cells showed kinetics characteristic of HK and LK membranes of domestic goats and sheep; the ATPase of LK Barbary sheep membranes sensitized with anti-L was stimulated 2-fold due to an alteration in the internal sodium and potassium affinities in favour of sodium.