Thermoresponsive poly(N-vinylcaprolactam) cryogels: synthesis and its biophysical evaluation for tissue engineering applications.

The thermoresponsive poly(N-vinylcaprolactam) (PVCl) based cryogel network were synthesized and characterized with respect to physical and biological properties. The PVCl cryogel crosslinked with polyethylene glycol-diacrylate (PEGda) was synthesized in 1% dimethyl sulfoxide containing aqueous medium at -12°C for 12-14 h. The cryogel synthesized in this manner were highly spongy in nature and can absorb water in its porous network. These polymeric cryogel networks have good physical morphology as confirmed by scanning electron microscopy. The estimated porosity of these cryogels was 90% as demonstrated by various methods based on absorption of water and cyclohexane. The median pore diameter and surface area was 30 µm and 2.0253 m(2)/g, respectively as confirmed by analysis on mercury porosimeter. These materials can interact with biological system without any cytotoxic effects. Change in temperature influenced the adsorption of fetal bovine serum (FBS) on PVCl scaffold which showed maximum protein adsorption at 37°C, as compared to that at 25°C. Furthermore, the fibroblast cell adhesion studies showed the potential of these PVCl based cryogels as tissue engineering scaffolds.

Seizures and dermatitis after exposure to caprolactam.

A 22-year-old man was initially seen with dermatitis, fever, and seizures after three days of occupational exposure to caprolactam, a nylon fiber precursor. A comprehensive neurological investigation showed no organic CNS abnormalities. Although caprolactam has been shown to induce convulsive disorders in experimental animals, to our knowledge, there are no reports of caprolactam-induced seizures in man. The coincidence of typical skin lesions with otherwise unexplained grand mal seizures in this strongly suggests that caprolactam was the cause.

Reaction of the human gingival tissue to different suture materials used in periodontal surgery.

The gingival reaction to 4 different suture materials used in periodontal surgery was studied in 36 patients. The gingiva was sutured prior to surgery and biopsies were taken at 3, 7 and 14 days to observe the tissue reaction. The histological examination showed that silk caused the most intense and longest inflammatory response. Polyester and perlon provoked shorter, less intense tissue reactions than silk, and nylon caused the least inflammatory response, with earlier tissue repair.

[Liver cell function test based on selective laboratory studies]. / Próba oceny wydolnosci komórki watrobowej na podstawie wybranych badan laboratoryjnych.

Laboratory tests have been carried out in 517 workers of a Chemical Fibres Plant. This was aimed at the detection of the changes resulting from cumulative exposure to caprolactam, dowtherm and physical factors. There have been performed hematological investigations, uninalyses and biochemical tests: total protein level, activity of enzymes: ASPAT, ALAT, PA, ChE, thymol test. The results have been analysed as the mean values for particular divisions and workstands; then they have been compared with standards. In order to evaluate the degree of occupational exposure of particular groups of workers, an index of the liver cell damage has been calculated. It was expressed in % of the results exceeding the standards in relation to all results in a given group of workers. The highest values of the index were those in the group employed at the polymerization division. The authoresses promote the advisability of special care for this group of workers.

[Evaluation of the circulatory system in workers exposed to caprolactam and diphenyl in 1 of the chemical plants producing polyamine fibers]. / Ocena stanu ukladu krazenia u pracowników eksponowanych na kaprolaktam i dwufenyl w jednym z zakladów chemicznych produkujacych wlókna poliamidowe.

The literature data indicating nonspecific pathologic symptoms of the circulatory system in those occupationally exposed to caprolactam and diphenyl inspired the authors to evaluate the circulatory system in a group of 495 workers of a Chemical Plant producing polyamide fibres. The anamnestic data, family inquiry and subjective changes indicate that any hints of the significant effects of the technological process on circulatory diseases in this professional group are unwarranted. The percentage values of the latent circulatory failure (1-2% of subjects), coronary insufficiency (6.6% of subjects), arterial hypertension (5.7% of subjects) did not show any significant differences, as compared to the control group and normal Polish population. The obtained results of ECG test evaluated according to the Minnesota-Code criterion did not significantly differ from 100 controls composed of those in whom no changes in the circulatory system were found, whereas clear differences were found related to 50 persons with documented heart ischemia.

[A comparative assessment of modern suture materials in stomach resection]. / Sravnitel'naia otsenka sovremennykh shovnykh materialov pri rezektsii zheludka.

Results of stomach resection by Bilrot-II in 30 experimental animals and 369 patients with gastric and duodenal ulcers were analyzed. Gastroenteroanastomoses were created with various sutures: capron, polysorb, titanium clips. Pneumopression, bacteriologic and morphologic examinations of anastomosis, fibroesophagogastroduodeno- and intestinoscopy, peripheral computed electrogastroenterography were used. It was revealed that mechanical suture with titanium clips was the best. Polysorb thread is inferior in tissue reaction to mechanical suture but superior to capron. Use of polysorb reduced rate of complications in immediate postoperative period 4 times. Taking into consideration high cost of suture devices it is reasonable to introduce polysorb in practice of abdominal surgery.

[Causes of anastomositis after gastric resection]. / O prichinakh anastomozita posle rezektsii zheludka.

The control fibrogastroscopy of the resected stomach in patients showing the clinical picture of postoperative anastomositis has proved that the application of an unresolving suture material (caprone) for a marginal suture of gastroenteroanastomosis causes post-resection inflammation of anastomosis in about 50% of cases. For improvement of surgical results the authors suggest to substitute marginal caprone sutures with catgut or tantal agraffes.

The results of 1000 intracapsular cataract extraction with the suture-fixated Medallion lens implant.

One thousand intracapsular medallion implants, performed between August 1975 and July 1980, were analyzed for complications (minimum follow-up 6 months): cystoid macular edema, 6.5%; retinal detachment, 2.8%; corneal edema, 0.9%; aphakic glaucoma, 2.5%; suture failure, 9%; implant subluxation, 3.7%; implant dislocation, 2%; and implant removal, 0.6%. Visual acuity of 20/40 or better was achieved in 93.4% of the cases, excluding non-implant related causes of low visual acuity.

Extraocular muscle transplantation.

1. The transplantation of extraocular homografts in dogs and humans has been described. 2. The extraocular muscle tissue transplanted remains viable, but loses its characteristics of muscle tissue during the period of the normal healing process following extraocular muscle surgery. 3. Autogenous homograft of extraocular muscle has an advantage over artificial synthetic material with the absence of extrusion and less reaction. 4. This is a clinically usable procedure today, especially in the amblyopic ehe with high deviation to accomplish an additional lengthening of one extraocular muscle, particularly if extraocular muscle surgery has previously been performed.

Three-generation reproduction study with caprolactam in rats.

In a three-generation reproduction study, rats were given caprolactam in the diet of 0, 1000, 5000 and 10,000 ppm. No treatment-related effects were observed in the parental animals with respect to mortality, clinical signs, reproductive performance or gross pathology findings. Consistently lower body weights were noted in the P2 and P3 mid- and high-dose males and females. Consistently lower mean food consumption values were noted in the P2 and P3 mid- and high-dose males and the high-dose females. These differences were generally significant (P less than or equal to 0.05) in the high-dose group of both sexes. Compound-related histopathologic findings noted in the high-dose P1 males consisted of a slight increase in the severity of spontaneous nephropathies, occasionally accompanied by granular casts. The offspring data revealed no treatment-related effect with respect to gross appearance, gross pathology, survival, number of pups, percentage of male pups or kidney weight. Analysis of the offspring body weights on Days 1, 7 and 21 of lactation revealed consistently and generally significant lower mean values in the high-dose male and female animals of all filial generations. The mean body weights of both sexes in the mid-dose group were generally lower than those of the controls. The effects on mean body weight, mean food consumption and the group increases in the severity of nephropathy, accompanied by the presence of granular casts in some animals, are considered to be related to the administration of caprolactam.

Critical effects and exposure limits.

The use of critical effects in the determination of occupational exposure limits (OELs) in Sweden is subjected to a statistical study. Many of the present OELs are high in relation to known no-effect levels and effect levels, and the degree of protection has a surprisingly weak correlation with the seriousness of the adverse effect. Several proposals for improved procedures are put forward. One of these is to supplement the concept of critical effects with that of dominant effects. A dominant effect of a substance is a health effect that is at some concentration the most serious health effect.