Zwitterionic Peptides Reduce Accumulation of Marine and Freshwater Biofilm Formers

Zwitterionic peptides are facile low-fouling compounds for environmental applications as they are biocompatible and fully biodegradable as their degradation products are just amino acids. Here, a set of histidine (H) and glutamic acid (E), as well as lysine (K) and glutamic acid (E) based peptide sequences with zwitterionic properties were synthesized. Both oligopeptides (KE)₄K and (HE)₄H were synthesized in d and l configurations to test their ability to resist the nonspecific adsorption of the proteins lysozyme and fibrinogen. The coatings were additionally tested against the attachment of the marine organisms Navicula perminuta and Cobetia marina as well as the freshwater bacterium Pseudomonas fluorescens on the developed coatings. While the peptides containing lysine performed better in protein resistance assays and against freshwater bacteria, the sequences containing histidine were generally more resistant against marine organisms. The contribution of amino acid-intrinsic properties such as side chain pK_a values and hydrophobicity, as well as external parameters such as pH and salinity of fresh water and seawater on the resistance of the coatings is discussed. In this way, a detailed picture emerges as to which zwitterionic sequences show advantages in future generations of biocompatible, sustainable, and nontoxic fouling release coatings.

Effect of Multilayer Termination on Nonspecific Protein Adsorption and Antifouling Activity of Alginate-Based Layer-by-Layer Coatings

Layer-by-layer (LbL) assembly is a versatile platform for applying coatings and studying the properties of promising compounds for antifouling applications. Here, alginate-based LbL coatings were fabricated by alternating the deposition of alginic acid and chitosan or polyethylenimine to form multilayer coatings. Films were prepared with either odd or even bilayer numbers to investigate if the termination of the LbL coatings affects the physicochemical properties, resistance against the nonspecific adsorption (NSA) of proteins, and antifouling efficacy. The hydrophilic films, which were characterized using spectroscopic ellipsometry, water contact angle goniometry, ATR-FTIR spectroscopy, AFM, XPS, and SPR spectroscopy, revealed high swelling in water and strongly reduced the NSA of proteins compared to the hydrophobic reference. While the choice of the polycation was important for the protein resistance of the LbL coatings, the termination mattered less. The attachment of diatoms and settling of barnacle cypris larvae revealed good antifouling properties that were controlled by the termination and the charge density of the LbL films.

Visible light-induced controlled surface grafting polymerization of hydroxyethyl methacrylate from isopropylthioxanthone semipinacol-terminated organic monolayers

Reaction scheme of the visible light-induced controlled surface grafting polymerization of methacrylate monomers onto organosilane-coated silicon initiated by previously coupled dormant ITXSP groups.

Low Fouling Peptides with an All (d) Amino Acid Sequence Provide Enhanced Stability against Proteolytic Degradation While Maintaining Low Antifouling Properties

Peptide-functionalized surfaces, composed of optimized l-peptides, show a high resistance toward nonspecific adsorption of proteins. As l-peptides are known to be prone to proteolytic degradation, the aim of this work is to enhance the stability against enzymatic degradation by using the all d-peptide mirror image of the optimized l-peptides and to determine if the all d-enantiomer retains the protein-resistant and antifouling properties. Two l-peptides and their d-peptide mirror images, some of them containing the nonproteinogenic amino acid α-aminoisobutyric acid (Aib), were synthesized and tested against non-specific adsorption of the proteins lysozyme and fibrinogen and the settlement of marine diatom Navicula perminuta and marine bacteria Cobetia marina. Both the d-enantiomer and the insertion of Aib protected the peptides from proteolytic degradation. Protein resistance was enhanced with the d-enantiomers while maintaining the resistance toward diatoms.

Prevalence of opioid abuse in interventional pain medicine practice settings: a randomized clinical evaluation

While drug therapy is one of the most commonly used modalities of treatment in managing persistent or chronic pain, controversy continues with regards to the appropriate use of controlled substances, specifically opioid analgesics, in interventional pain medicine settings. This study included 100 randomly selected patients receiving opioids in an interventional pain medicine setting. The patient's controlled substance profile was evaluated using multiple means. The patients were divided into two groups, with 76 patients in the non-abuse group and 24 patients in the abuse group after data collection. There were no significant differences noted either in demographic characteristics or psychological characteristics, except for a higher prevalence of depression in the abuse group. In conclusion, there was significant abuse of opioids in an interventional pain medicine setting, with an incidence of 24%, with frequent abuse seen in almost half of these patients. Thus, it is important for interventional pain physicians to recognize this possibility and also to recognize that there is no definite physiologic, psychologic or demographic information to suggest abuse, even though depression was more prevalent in abuse patients.

Influence of psychological factors on the ability to diagnose chronic low back pain of facet joint origin

This study was designed to determine the prevalence of lumbar facet joint pain in patients suffering with or without somatization disorder. The study was performed using comparative local anesthetic blocks. One hundred consecutive patients with chronic low back pain, with or without somatization, were evaluated. The results showed that, among patients suffering with chronic low back pain, 44% of the patients without somatization and 38% of the patients with somatization were positive for facet joint pain. The diagnosis of facet joint pain was not influenced by the presence or absence of somatization disorder. The evaluation also was extended to depression, generalized anxiety disorder and combinations with or without somatization thereof which showed no significant differences in the prevalence of facet joint pain. The results of this study demonstrated that the facet joint was a source of pain in chronic low back pain patients in 44% of the patients without somatization and 38% of the patients with somatization. This study also showed that there was no correlation between the presence or absence of facet joint pain and the presence or absence of somatization disorder or any other psychological condition or combination thereof.

Characteristics of chronic low back pain in patients in an interventional pain management setting: a prospective evaluation

Chronic low back pain patients are seen in multiple practice settings and managed with a multitude of therapeutic interventions. Studies conducted by various groups have made some generalizations in the literature describing low back pain patients. However, there are no studies evaluating the demographic features of patients presenting to therapeutic interventional pain medicine programs. This prospective study was undertaken to evaluate and explore various demographic features of patients with chronic low back pain presenting to a therapeutic interventional pain medicine program. Two hundred patients were studied, with evaluation of demographic features of age, mode of onset of pain, work status, history of surgery, and pain characteristics. The results showed that, among patients presenting to an interventional pain medicine program, 17% are over 65 years of age: they are predominantly women; two thirds are either overweight or obese; the mean duration of pain is 7 years, predominantly involving multiple regions, with an average pain intensity of 7.6, significant associated psychological conditions; they have undergone multiple interventions, and were seen by, on average, six physicians; and the majority of patients were not employed, with 31% unemployed and 52% disabled or retired.

Role of one day epidural adhesiolysis in management of chronic low back pain: a randomized clinical trial

Epidural fibrosis is seen as a common phenomenon among postlumbar laminectomy syndrome patients, contributing to approximately 60% of symptom recurrence. Percutaneous epidural lysis of adhesions has been described as a modality to effectively manage chronic low back pain secondary to epidural fibrosis. Forty-five patients were randomly assigned, with fifteen patients in the control group, or Group I, who were treated with conservative modalities of treatments, including medication, physical therapy, and an exercise program; and, thirty patients in Group II, who were treated with percutaneous epidural adhesiolysis and hypertonic saline neurolysis. The patients were evaluated over a period of 1 1/2 years to 3 years. Results showed that cumulative relief, defined as relief greater than 50% with one to three injections, in the treatment group was 97% at 3 months, 93% at 6 months, and 47% at 1 year. The study also showed that overall health status improved significantly in the treatment group in all parameters with average pain, physical health, mental health, functional status, psychological status and narcotic intake. Analysis also showed that this is a cost-effective treatment, with cost for 1-year improvement of quality of life at $2693. In conclusion, epidural adhesiolysis with hypertonic saline neurolysis performed on a 1-day basis is an effective modality of treatment in managing chronic low back pain in patients who failed to respond to fluoroscopically directed epidural steroid injections and also were demonstrated not to have facet joint mediated pain.

Effectiveness of lumbar facet joint nerve blocks in chronic low back pain: a randomized clinical trial

This randomized clinical trial was designed to determine the effectiveness of therapeutic lumbar facet joint nerve blocks. Two hundred patients were evaluated with controlled diagnostic blocks for the presence of facet joint mediated pain. Eighty four patients, or 42% were determined to have lumbar facet joint mediated pain. These patients were randomly allocated into two groups: Group I receiving therapeutic injections with local anesthetic and Sarapin, and Group II receiving therapeutic injections with a mixture of local anesthetic, Sarapin, and methyl prednisolone. A total of 73 patients were treated with medial branch blocks under fluoroscopy. Results showed that patients underwent multiple procedures over a period of 2(1/2) years. The mean number of procedures or interventions was 2.5 +/- 0.09 from 1 to 3 months, whereas it was 4 +/- 0.13 for 4 to 6 months, 6.1 +/- 0.21 for 7 to 12 months, and 8.4 +/- 0.31 for 13 to 32 months. Cumulative significant relief with one to three injections was 100% up to 1 to 3 months, 82% for 4 to 6 months, 21% for 7 to 12 months, and 10% after 12 months, with a mean relief of 6.5 +/- 0.76 months. There was significant improvement noted in overall health status with improvement not only in pain relief, but also with physical, functional, and psychological status, as well as return-to-work status. In conclusion, the results of this study demonstrate that medial branch blocks with local anesthetic and Sarapin, with or without steroids, are a cost effective modality of treatment, resulting in improvement in pain status, physical status, psychological status, functional status and return to work.