A topological approach to selecting models of biological experiments.

We use topological data analysis as a tool to analyze the fit of mathematical models to experimental data. This study is built on data obtained from motion tracking groups of aphids in [Nilsen et al., PLOS One, 2013] and two random walk models that were proposed to describe the data. One model incorporates social interactions between the insects via a functional dependence on an aphid's distance to its nearest neighbor. The second model is a control model that ignores this dependence. We compare data from each model to data from experiment by performing statistical tests based on three different sets of measures. First, we use time series of order parameters commonly used in collective motion studies. These order parameters measure the overall polarization and angular momentum of the group, and do not rely on a priori knowledge of the models that produced the data. Second, we use order parameter time series that do rely on a priori knowledge, namely average distance to nearest neighbor and percentage of aphids moving. Third, we use computational persistent homology to calculate topological signatures of the data. Analysis of the a priori order parameters indicates that the interactive model better describes the experimental data than the control model does. The topological approach performs as well as these a priori order parameters and better than the other order parameters, suggesting the utility of the topological approach in the absence of specific knowledge of mechanisms underlying the data.

Experimental study and analytical model of deformation of magnetostrictive films as applied to mirrors for x-ray space telescopes.

The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.

In vivo investigation of the efficiency of a nanoparticle-emulsion containing polihexanide on the human skin.

Skin antisepsis is a key element for the prevention of surgical site infections, as well as for infections after injection and punctures. Recent investigations have shown that about 25% of the resident bacterial flora of the human skin resides within the hair follicle. These findings strongly suggest that the skin appendages play the role of a bacterial reservoir. The bacteria within the hair follicles therefore may be the cause of endogenous germ repopulation after skin antisepsis, highlighting the need for new antiseptic formulations that can sufficiently penetrate into the hair follicles. Various experiments have found that nano-sized particles as well as oil-in-water emulsions are efficient carriers for substances into the hair follicles. In the present study, we investigated the in vivo antiseptic potential of the particle-associated and aqueous polihexanide on the human skin by monitoring bacterial growth after antisepsis over a period of 2.5h. The experiments suggest that the use of a particle-bound antiseptic can achieve a better and longer lasting antisepsis of the human skin than in non-particulate form.

MRI graduation of osseous reaction and drill hole consolidation after arthroscopic Bankart repair with PLLA anchors and the clinical relevance.

PURPOSE: Conventionally, radiography studies revealed prolonged glenoidal drill hole visibilities with an unclear influence to the clinical outcome after arthroscopic Bankart repair using Poly-Laevo-Lactic-Acid (PLLA) anchors. The primary aim of the present study was the separated assessment of drill hole consolidation (DHC) and the concomitant osseous reaction (OR) of the glenoidal bio-degradation process in new specific magnetic resonance grading systems. In accordance with the specific DHC and the OR graduation, the clinical relevance was the secondary focus. METHODS: Twenty-eight patients with arthroscopic Bankart repair using knotless PLLA anchors were prospectively followed and analyzed using a clinical scoring system (3, 6, 15 and 32 months). The T2-weighted OR and T1-weighted DHC were assessed using specific magnetic resonance imaging grading protocols (15 and 32 months). RESULTS: Longitudinal assessments revealed successive clinical status improvements over time (32 months: Rowe 95.7 ± 3.8; Walch-Duplay 93.8 ± 6.6; Constant 93.9 ± 4.5; ASES 93.8 ± 6.9; DASH 28.6 ± 7.2; NAS(pain) 1.1 ± 1.3; NAS(function) 1.3 ± 1.4). The initial OR level regressed over the 15-32 month period while the DHC showed significant drill hole reductions (P < 0.05). The inferior glenoid revealed a significantly increased bio-degradation capacity (P < 0.05) with drill hole enlargements in 14.3%. Neither the OR nor the drill hole enlargements influenced the clinical status. In no case were clinical or radiologic signs for a foreign body reaction. CONCLUSION: Knotless bio-anchors provide secure glenoidal fixation for Bankart repair without any specific clinical or MR evidence of an inflammatory response. The clinical status remained unaffected by the bio-degradation process. LEVEL OF EVIDENCE: IV.

Regional-scale assessment of soil salinity in the Red River Valley using multi-year MODIS EVI and NDVI.

The ability to inventory and map soil salinity at regional scales remains a significant challenge to scientists concerned with the salinization of agricultural soils throughout the world. Previous attempts to use satellite or aerial imagery to assess soil salinity have found limited success in part because of the inability of methods to isolate the effects of soil salinity on vegetative growth from other factors. This study evaluated the use of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery in conjunction with directed soil sampling to assess and map soil salinity at a regional scale (i.e., 10-10(5) km(2)) in a parsimonious manner. Correlations with three soil salinity ground truth datasets differing in scale were made in Kittson County within the Red River Valley (RRV) of North Dakota and Minnesota, an area where soil salinity assessment is a top priority for the Natural Resource Conservation Service (NRCS). Multi-year MODIS imagery was used to mitigate the influence of temporally dynamic factors such as weather, pests, disease, and management influences. The average of the MODIS enhanced vegetation index (EVI) for a 7-yr period exhibited a strong relationship with soil salinity in all three datasets, and outperformed the normalized difference vegetation index (NDVI). One-third to one-half of the spatial variability in soil salinity could be captured by measuring average MODIS EVI and whether the land qualified for the Conservation Reserve Program (a USDA program that sets aside marginally productive land based on conservation principles). The approach has the practical simplicity to allow broad application in areas where limited resources are available for salinity assessment.

Geochemistry in the modern soil survey program.

Elemental analysis has played an important role in the characterization of soils since inception of the soil survey in the US. Recent efforts in analysis of trace and major elements (geochemistry) have provided necessary data to soil survey users in a variety of areas. The first part of this paper provides a brief overview of elemental sources, forms, mobility, and bioavailability; critical aspects important to users of soil survey geochemical data for appropriate use and interpretations. Examples are provided based on data gathered as part of the US soil survey program. The second part addresses the organization of sample collection in soil survey and how soil surveys are ideally suited as a sampling strategy for soil geochemical studies. Geochemistry is functional in characterization of soil types, determining soil processes, ecological evaluation, or issues related to soil quality and health, such as evaluating suitability of soils for urban or agricultural land use. Applications of geochemistry are on-going across the US and are documented herein. This analytical direction of soil survey complements historic efforts of the National Cooperative Soil Survey Program and addresses the increasing need of soil survey users for data that assists in understanding the influence of human activities on soil properties.

Evaluation of the VIDAS Listeria (LIS) immunoassay for the detection of Listeria in foods using demi-Fraser and Fraser enrichment broths, as modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06).

A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.

[Minimally invasive percutaneous epidural neurolysis in chronic radiculopathy. A prospective controlled pilot study to prove effectiveness]. / Die minimal-invasive perkutane epidurale Neurolyse beim chronischen Nervenwurzelreizsyndrom. Eine prospektive kontrollierte Pilotstudie zum Wirksamkeitsnachweis.

The treatment of chronic back pain with sciatica is still an unsolved therapeutic challenge. Percutaneous minimally invasive neurolysis according to the Racz technique is increasingly applied and discussed controversially. So far there is no prospective randomized controlled study for evaluation of a possible treatment effect. In a prospective pilot study, 25 patients with monosegmental radiculopathy of the lumbar spine were treated with minimally invasive percutaneous epidural neurolysis according to Racz's technique. They all suffered from chronic disc herniations or failed back syndromes after surgery, all with radiculopathy. The average age of the patients was 51+/-16 years, the average duration of the symptoms was 28 months. Twelve weeks after the procedure patients had significant clinical improvement. The Oswestry score increased from 64+/-17 to 22+/-12 points. Subjective pain sensation according to the McNab score showed improvement too. None of the patients had worsening of the situation compared to preoperative findings. No clinically relevant complications were observed. The results are being used to design a clinical trial in accordance with good clinical practice guidelines to analyze the therapeutic efficacy of the procedure. The described technique is still a clinically experimental procedure. However, due to a low probability of side effects and due to the good results reported so far by most authors, the Racz catheter technique may be applied in certain patients with chronic radiculopathy refractory to conservative treatment.

Expression, purification, and characterization of active recombinant prostate-specific antigen in Pichia pastoris (yeast).

BACKGROUND: Prostate-specific antigen (PSA), a member of the kallikrein family of serine proteases, is a chymotrypsin-like glycoprotein produced by the prostate epithelium. Elevated serum PSA (> 4 ng/ml) is a tumor marker for prostatic cancer and benign prostatic hypertrophy; increasing serum PSA over time is indicative of metastatic disease. It has been suggested that PSA may contribute to tumor metastasis through degradation of extracellular matrix glycoproteins, as well as cleavage of IGF binding protein-3, a modulator of IGF-1. To elucidate the role of PSA in the development and progression of prostatic cancer, it is necessary to have a reliable, cost-effective source of enzymatically active protein. Previous efforts to express recombinant PSA (rPSA) produced inactive proPSA, or mixtures of active and inactive PSA requiring activation by removal of the propeptide. We describe the expression of active recombinant mature PSA in yeast. METHODS: Stable chromosomal integration of a construct consisting of the yeast alpha-factor signal sequence preceding the mature PSA sequence resulted in secretion of rPSA. The rPSA was purified from the yeast cell culture supernatant to homogeneity by strong cation-exchange chromatography, and characterized by SDS-PAGE, Western analysis, electrospray mass spectrometry, N-glycanase digestion, N-terminal amino acid sequencing, and inactivation by a PSA-specific inhibitor. RESULTS: We report the production of active, mature rPSA in Pichia pastoris. Two forms of rPSA varying slightly in glycosylation were identified. The specific activity of the rPSA was equal to that of human seminal plasma PSA (0.56 micromol/min mg) as determined using a chromogenic substrate. CONCLUSIONS: Large-scale production of active rPSA will be useful in the exploration of PSA effects on tumor cell proliferation, migration and metastasis. In addition, a large supply of enzyme should facilitate the discovery of novel inhibitors for in vitro and in vivo evaluation, and may provide a reproducible source of rPSA for use as a standard in diagnostic testing.

[Successful treatment of gastroesophageal reflux with anterior partial fundoplication under celioscopy]. / Cure du reflux gastro-oesophagien par fundoplicature partielle antérieure sous coelioscopie.

OBJECTIVE: To study the interest of partial fundoplication under laparoscopy, not only in terms of efficacy but also in the low rate of complications. METHODS: The study included all patients having undergone coelioscopic surgery for gastroesophageal reflux from January 1995 to February. A ventral semi-valve was created in all patients. Complications during surgery and post-surgical follow-up immediately after, six weeks later and then at distance were analyzed. RESULTS: The mean duration of surgery was 81 minutes (40-170 min.) and mean hospital stay 6.2 days (2-12 days). Twelve conversions were observed (9.6%) and post-surgical morbidity was of 9.7% after coelioscopy. At 6 weeks, 72 patients (63.7%) were satisfied with the operation, 13 patients (11.5%) complained of dysphagia and 5 (4.4%) of bloating. At distance, after a mean of 3.2 years (0.5-5.5 years), 72 patients (73%) were totally satisfied; 4 presented recurrent reflux (4.1%) and 3 patients (3.1%) complained of dysphagia. CONCLUSION: The results of laparoscopic surgery for gastroesophageal reflux with creation of a ventral semi-valve are encouraging. Pre-existing symptomatology is eradicated and post-surgical complications are clearly decreased.

[Carcinomatous degeneration of augmentation enterocystoplasty]. / Dégénérescence carcinomateuse des entérocystoplasties d'agrandissement.

Augmentation enterocystoplasties are performed increasingly frequently and their indications are no longer exclusively limited to small tuberculous bladders. One of the most serious complications of these procedures is malignant transformation, as reported in the present case. Carcinomatous degeneration is uncommon and usually occurs more than ten years after enterocystoplasty. Patients treated by this operation must be submitted to annual cystoscopy combined with guided biopsies at the slightest doubt. This surveillance should be started between the 5th and the 10th postoperative year.

Leptin is a four-helix bundle: secondary structure by NMR.

Leptin is a signaling protein that in its mutant forms has been associated with obesity and Type II diabetes. The lack of sequence similarity has precluded analogies based on structural resemblance to known systems. Backbone NMR signals for mouse leptin (13C/15N -labeled) have been assigned and its secondary structure reveals it to be a four-helix bundle cytokine. Helix lengths and disulfide pattern are in agreement with leptin as a member of the short-helix cytokine family. A three-dimensional model was built verifying the mechanical consistency of the identified elements with a short-helix cytokine core.

Comparison of outpatient laparoscopic cholecystectomy in a private nonteaching hospital versus a private teaching community hospital.

The development of laparoscopic cholecystectomy has allowed the introduction of outpatient surgery for biliary tract disease. However, there appears to be a wide variation of the interpretation of "outpatient surgery," ranging from discharge the same day to keeping patients for overnight observation. We prospectively reviewed the last 50 chole-cystectomies performed at Spartanburg Regional Medical Center, a private teaching institution, and Upstate Carolina Medical Center, a private nonteaching hospital. All cholecystectomies were performed by board certified surgeons or surgical residents under the supervision of board certified surgeons. Spartanburg Regional Medical Center's standard was 23-hour observation with 9 patients (18%) being discharged home the day of surgery. Upstate Carolina Medical Center's standard was discharge home (usually 4-8 hours after completion of the procedure) with 39 patients (78%) discharged the same day. No patient discharged the same day presented back with any significant complication. Comorbid disease, biliary pancreatitis, ascending cholangitis, gangrenous gallbladder, extreme age and living conditions and conversion to open were factors considered for admission. Intra-operative difficulty such as oozing, excessive adhesiolysis, postoperative nausea, vomiting or pain control were also indications for overnight admissions. The extra 15 to 19 hours for routine observation did not change any treatment for any of the 41 patients and resulted in additional cost to the hospital of approximately $15,000. We conclude that same day, outpatient laparoscopic cholecystectomy can be done safely with discharge home 4 to 8 hours postoperative without significant morbidity in selective patients.

A study of stairs in the housing of independently-living elderly people.

This survey study focuses on stairs in the homes of a substantial number of independently living elderly (60+) residents of a community in which there are mostly multistory houses and apartment buildings with stairs. While the majority could climb their stairs without problems, a substantial minority lived with stairs despite difficulty and even inability in climbing them. Most people were satisfied with their homes, and many were unwilling to admit that stairs were a present or potential problem. Most people, including most with stair problems, had no plans to move from their homes, however, a majority was willing to concede under questioning that stair-free living in a presently unplanned next home would be desirable. There is a plea that stairs be of increased concern in the housing of elderly people, and that there be increased planning for stair-free homes.

A comparative study of cefepime and ceftazidime in the treatment of community-acquired lower respiratory tract infections.

Antibiotic treatment for community-acquired pneumonia must target Gram-positive pathogens, especially frequently isolated organisms such as Streptococcus pneumoniae. The severity of community-acquired pneumonia is often related to underlying factors. Occasionally it may be complicated by staphylococcal or Gram-negative bacillary infection. We have compared the safety and efficacy of cefepime 1 g bd with ceftazidime 1 g tds as empirical treatment in adults with community-acquired lower respiratory tract infections (LRTIs). One hundred and thirty-one patients with moderate to severe LRTIs were randomized to two treatment groups: 87 received cefepime and 44 received ceftazidime. The treatment groups were comparable with regard to sex, age and treatment duration. Of the 116 pathogens isolated, 57 were Gram-positive (46 strains of S. pneumoniae) and 59 were Gram-negative (33 strains of Haemophilus influenzae). Of the 111 patients evaluated, clinical cure rates were 87% (65/75) in the cefepime group and 86% (31/36) in the ceftazidime group. Pathogen eradication rates were 95% (74/78 and 36/37, respectively) in both groups. Both drugs were well tolerated and the incidence of adverse events in each group was comparable. Cefepime 2 g per day (1 g bd) was as safe and effective as ceftazidime 3 g per day (1 g tds) in the treatment of community-acquired LRTIs.

[Therapy of Wegener's granulomatosis. Experiences with conventional and stage-adjusted treatment in 111 patients over 24 years]. / Die Therapie der Wegenerschen Granulomatose. Erfahrungen mit der konventionellen und der stadienadaptierten Behandlung bei 111 Patienten während 24 Jahren.

Treatment and outcome of 111 patients who fell ill with Wegener's granulomatosis (WG) between 1966 and 1990 were analysed retrospectively. The mean observation time after diagnosis had been 47 (1-288) months. At the time of diagnosis 37 patients suffered from locoregional symptoms only, whereas the disease was generalised in 74 patients. Two regimes of treatment were differentiated: "conventional" treatment, i.e. daily application of cyclophosphamide/prednisolone (FAUCI scheme) or azathioprine/prednisolone or prednisolone alone, and "stage-adapted" treatment, characterised by change of different treatments (e.g. cyclophosphamide pulse therapy, cotrimoxazole) according to the extent and activity of disease. In patients who received stage-adapted treatment, relapses occurred significantly more frequently than in conventionally treated patients. On the other hand, lethal outcome was much more frequent in conventionally treated patients.

Treatment of Wegener's granulomatosis.

Treatment and outcome of 111 patients who fell ill with Wegener's granulomatosis (WG) between 1966 and 1990 were analysed retrospectively. Two regimens of treatment were distinguished: "conventional" treatment, i.e. daily application of cyclophosphamide/corticosteroids (FAUCI scheme) or azathioprine/corticosteroids or corticosteroids alone, and "stage-adapted" treatment, characterized by change of different treatments (e.g. cyclophosphamide pulse therapy, cotrimoxazole) according to the extent and activity of disease. In patients who received stage-adapted treatment, exacerbations occurred significantly more frequent than in conventionally treated patients, while lethal outcome was much more frequent in conventionally treated patients.