Gellan Gum-based luminal fillers for peripheral nerve regeneration: an in vivo study in the rat sciatic nerve repair model.

Peripheral nerve injuries (PNI) resulting in a gap to be bridged between the transected nerve ends are commonly reconstructed with autologous nerve tissue, but there is a need for valuable alternatives. This experimental work considers the innovative use of the biomaterial Gellan Gum (GG) as a luminal filler for nerve guidance channels made from chitosan with a 5% degree of acetylation. The engineered constructs should remodel the structural support given to regenerating axons by the so-called bands of Büngner. Four different GG formulations were produced by combining varying amounts of High-Acyl GG (HA-GG) and Methacrylated GG (MA-GG). The effective porosity of the freeze-dried networks was analysed by SEM and micro-CT 3D reconstructions, while the degradation and swelling abilities were characterized in vitro for up to 30 days. The metabolic activity and viability of immortalized Schwann cells seeded onto the freeze-dried networks were also evaluated. Finally, the developed hydrogel formulations were freeze-dried within the chitosan nerve guides and implanted in a 10 mm rat sciatic nerve defect. Functional and histomorphological analyses after 3, 6, and 12 weeks in vivo revealed that although it did not result in improved nerve regeneration, the NGC25:75 formulations could provide a basis for further development of GG scaffolds as luminal fillers for hollow nerve guidance channels.

Serendipity, science, and a new hantavirus.

This essay follows a team of scientific investigators step by intriguing step as it pursues the cause of the mysterious 1993 deaths of healthy young adults in the southwestern United States. Using the science of the day, the team unravels the elusive origin of a potentially widespread killer--tracking a new hantavirus to its home, tracing its lineage, and differentiating its DNA from the large hantavirus family. This is the first in the "Breakthroughs" series.

Evaluating the preservative effectiveness of RGP lens care solutions.

We examined the antimicrobial preservative efficacy of nine rigid gas permeable (RGP) contact lens care solutions by challenging them in a laboratory study with both standard test organisms and preservative-resistant strains. Solutions containing polyhexamethylene biguanide (PHMB), such as Boston Advance (15 ppm) and a Boston Advance Enhanced Comfort Formula (5 ppm PHMB + 30 ppm chlorhexidine gluconate [CHG]) were most effective at rapidly killing vegetative cells, killing all bacteria and yeast by 6 hours. Boston Advance only slightly reduced the number of Aspergillus niger spores during the 28 day study, but Boston Advance Enhanced Comfort Formula reduced the spores by almost 3 logs by 14 days and by 4 logs by 21 days. Thimerosal-preserved Soaclens only reduced Staphylococcus aureus by 1 log at 6 hours, but at 1 day all tested organisms including S. aureus and A. niger were killed. Barnes Hind Gas Permeable Wetting and Soaking Solution, containing 50 ppm CHG, had little effect on adapted Serratia marcescens or Pseudomonas cepacia during the 28 day study. Allergan Wet-N-Soak Plus, containing 30 ppm benzalkonium chloride (BAK), was also unable to kill adapted S. marcescens or P. cepacia. CIBA Vision Premus (40 ppm BAK) was unable to kill adapted S. marcescens. Alcon Opti-Free, with 50 ppm polyquaternium-1 (polyquad), did not kill P. cepacia. Sherman Stay-Wet 3, containing 0.1% benzyl alcohol, was not effective against S. marcescens (adapted or unadapted), P. cepacia, or A. niger. Sherman DeStat 3, which contains 0.1% benzyl alcohol plus surfactants and five times the concentration of EDTA as in Stay-Wet 3, was able to kill all the vegetative cells by 7 days but did not significantly reduce A. niger.

Aluminium in some surface waters in Poland.

This paper describes the results of the study of water acidification and aluminium concentration. High concentration of aluminium was observed in water in Tatra Mts, Karkonosze Mts, Lysogóry Mts and on the south side of Barania Mountain. The concentration of aluminium exceeded many times toxic level for water living organisms.

Preoperative and postoperative assessment of nutrient intakes in patients who have undergone gastric bypass surgery.

The study of 25 morbidly obese patients who had undergone gastric bypass surgery was undertaken to determine the fat, carbohydrate (CHO), protein, and total caloric intake before and at 1, 3, 6, and 12 months postoperatively. No postoperative complications occurred, and all patients lost weight appropriately. The nutrient intakes were estimated from dietary recall. Dramatic decreases occurred in average total caloric intake from a preoperative value of 3979.4 to 351.6 kcal at 1 month, 471.3 kcal at 3 months, 932.7 kcal at 6 months, and 1091 kcal at 12 months. Fat, CHO, and protein intake decreased equally until 12 months when fat intake had reached a plateau while CHO and protein intake continued to rise. Weight reduction after gastric bypass surgery is related to decreased caloric intake, predominantly in the fat component.

The surgical treatment of morbid obesity: economic, psychosocial, ethical, preventive, medical aspects of health care.

Surgical treatment of morbid, familial, juvenile-onset obesity in a 37-year-old, 260-pound, mother of three children by jejunoileal bypass was subsequently converted to gastric bypass. The resulting weight loss of 110 pounds resulted in personality changes and changes in family dynamics and was followed by divorce. Medical, psychosocial, and economic aspects of the case are discussed.

Bulimia: the binge eating syndrome.

Bulimia occurs in roughly half of obese and anorexic patients. A recent study found 19% of female and 5% of male college students to be bulimic. Binge eating usually comes to the physician's attention from problems associated with purging measures--diuretics, laxatives, or self-induced postprandial vomiting--used by one out of ten bulimic patients. Continuous vomiting causes parotid enlargement, sore throat, spontaneous regurgitation, and severe electrolyte imbalance. We report a case illustrating the bulimic's distorted body image, review alternative treatment methods, and suggest needed areas of research, particularly those elucidating the relationship between bulimia and affective disorders.

Anorexia nervosa.

Anorexia nervosa typically occurs in a "model child" of a family that values achievement, appearance and nonconflictual interactions. Three diagnostic criteria are weight loss of at least 25 percent of ideal body weight, physiologic changes (including amenorrhea) and a distorted body image in which the patient, even when cachectic, insists she is fat. Therapy must involve the entire family, focusing not on pounds gained but on learning to handle conflict.