Carbon Dioxide Absorption During Inhalation Anesthesia: A Modern Practice.

CO2 absorbents were introduced into anesthesia practice in 1924 and are essential when using a circle system to minimize waste by reducing fresh gas flow to allow exhaled anesthetic agents to be rebreathed. For many years, absorbent formulations consisted of calcium hydroxide combined with strong bases like sodium and potassium hydroxide. When Sevoflurane and Desflurane were introduced, the potential for toxicity (compound A and CO, respectively) due to the interaction of these agents with absorbents became apparent. Studies demonstrated that strong bases added to calcium hydroxide were the cause of the toxicity, but that by eliminating potassium hydroxide and reducing the concentration of sodium hydroxide to <2%, compound A and CO production is no longer a concern. As a result, CO2 absorbents have been developed that contain little or no sodium hydroxide. These CO2 absorbent formulations can be used safely to minimize anesthetic waste by reducing fresh gas flow to approach closed-circuit conditions. Although absorbent formulations have been improved, practices persist that result in unnecessary waste of both anesthetic agents and absorbents. While CO2 absorbents may seem like a commodity item, differences in CO2 absorbent formulations can translate into significant performance differences, and the choice of absorbent should not be based on unit price alone. A modern practice of inhalation anesthesia utilizing a circle system to greatest effect requires reducing fresh gas flow to approach closed-circuit conditions, thoughtful selection of CO2 absorbent, and changing absorbents based on inspired CO2.

The treatment of ingrown nail: Chemical matricectomy with NAOH versus wedge resection.

Ingrown nail is a common problem seen in the dermatology clinics. The aim of this study is to compare the wedge resection method and chemical matricectomy with NaOH in terms of operation time, postoperative pain severity, postoperative drainage, recurrence rates, recovery time, and the effects of these two methods on Dermatology Quality of Life Index. This study included 60 patients. About 42 nail edges of 30 patients were treated with NaOH for chemical matricectomy and wedge resection was performed for 33 nail edges of 30 patients. Operation time for chemical matricectomy and wedge resection was an average of 7.66 ± 3.65 and 19.25 ± 5.54 min (p < .001). Recovery time was an average of 17.27 ± 14.22 days for chemical matricectomy and an average of 28.85 ± 17.03 days for wedge resection (p = .004). Recurrence was detected in 5.4% of the nail edges treated with chemical matricectomy and 3.6% of the nail edges treated with wedge resection (p = 1.000). Absence of differences for the recurrence rates between wedge resection method and chemical matricectomy method with NaOH shows that effectiveness of these approaches are similar. It seems that quite short operation and recovery times in the chemical matricectomy are the main advantage of the method.

Tractional Descemet's membrane detachment after ocular alkali burns: case reports and review of literature.

BACKGROUND: Descemet's membrane detachment (DMD) is a rare complication after ocular chemical injury and its pathogenesis remains unclear. In this study, we reported two cases of DMD with traction demonstrated on Anterior segment optical coherence tomography (AS-OCT). CASE PRESENTATION: Two patients sustained ocular chemical injury with 50% sodium hydroxide. In both cases, AS-OCT revealed detached Descemet's membrane that was adherent to the underlying iris tissue in the inferior quadrant at 45 days and 34 days after the injury respectively. The first case received intracameral tamponade with 12% C3F8 gas and the second case received corticosteroid and sodium chloride 5% eye drops. However, DMD persisted in both cases. CONCLUSIONS: The atypical features of DMD on anterior segment optical coherence tomography in our cases suggested the presence of an inflammatory component caused adhesions and traction of iris to Descemet's membrane and prevented reattachment of DMD even with gas tamponade.

A novel model approach for esophageal burns in rats: A comparison of three methods.

BACKGROUND: Corrosive esophageal injury causes serious clinical problems. We aimed to create a new experimental esophageal burn model using a single catheter without a surgical procedure. MATERIALS AND METHODS: We conducted the study with two groups of 12 male rats that fasted for 12 h before application. A modified Foley balloon catheter was inserted into the esophageal lumen. The control group was given 0.9% sodium chloride, while the experimental group was given 37.5% sodium hydroxide with the other part of the catheter. After 60s, esophagus was washed with distilled water. The killed rats were examined using histopathological methods after 28 days. RESULTS: In comparison with the histopathological changes experienced by the study groups, the control groups were observed to have no pathological changes. Basal cell degeneration, dermal edema, and a slight increase in the keratin layer and collagen density of submucosa due to stenosis were all observed in the group subjected to esophageal corrosion. CONCLUSION: A new burn model can thus, we believe, be created without the involvement of invasive laparoscopic surgery and general anesthesia. The burn in our experiment was formed in both the distal and proximal esophagus, as in other models; it can also be formed optionally in the entire esophagus.

Skin barrier integrity and natural moisturising factor levels after cumulative dermal exposure to alkaline agents in atopic dermatitis.

Dermal exposure to alkaline agents may lead to skin barrier damage and irritant contact dermatitis. The objective of this study was to investigate the effects of cumulative exposure to 0.5% sodium lauryl sulphate (SLS) and 0.15% NaOH on the barrier function and natural moisturising factor (NMF) levels in atopic dermatitis and healthy volunteers with known filaggrin genotype. The skin response was monitored by measurement of erythema and transepidermal water loss. The stratum corneum NMF levels were determined by high-performance liquid chromatography. Repeated exposure to 0.5% SLS and/or 0.15% NaOH in atopic dermatitis resulted in more severe impairment of the skin barrier function. Cumulative exposure to the irritants reduced significantly NMF in both the atopic and healthy controls group. The pronounced decrease of NMF after repeated single and sequential irritant exposure may be a pathogenetically relevant factor for development of chronic irritant contact dermatitis in both healthy and atopic individuals.

Preventing irritant contact dermatitis with protective creams: influence of the application dose.

BACKGROUND: Skin protection creams (PC)s are used in the occupational setting to help prevent irritant hand dermatitis. The actual amounts of PC applied and the resulting dose per unit area on hands at work are lower than recommended. OBJECTIVES: To assess the influence of the applied dose on the efficacy of PCs in the prevention of irritant contact dermatitis. METHODS: Experimental cumulative irritant contact dermatitis was induced by twice daily application of 0.5% NaOH or sodium lauryl sulfate (SLS) for 4 days on the backs of 20 healthy volunteers. Test areas were left unprotected or were pretreated with three different PCs applied at a low dose (2 mg/cm(2) ) or a high dose (20 mg/cm(2) ) before irritation. Irritant responses were assessed by visual scoring and measurement of transepidermal water loss, chromametry, and corneometry. RESULTS: Although cumulative irritant dermatitis developed in all unprotected test sites, irritation was significantly reduced in a dose-dependent manner on PC-protected sites. The higher doses of all PCs provided significant protection against irritation. However, the lower dose of one product did not significantly protect against SLS-induced irritation. CONCLUSIONS: The protective efficacy of PCs depends on the amount of product applied per unit skin surface area. Some products may show no protective efficacy when used at doses close to those practically applied at workplaces. Future efficacy studies of PCs should be performed with doses not higher than 2 mg/cm(2) , to avoid overestimation of their protective efficacy.

Therapeutic outcomes of one-minute application of sodium hydroxide versus phenol in the chemical cauterization of ingrown toenails.

BACKGROUND: Ingrown nails are frequently encountered in dermatology practice. The recurrence tendency of the disorder makes chemical cauterization essential during surgical procedures. In studies comparing nail matrix cauterization with sodium hydroxide (NaOH) versus phenol, phenol's application time was highly variable. OBJECTIVE: To compare the therapeutic outcomes of matrix cauterization for a standard duration of one minute for NaOH versus phenol in stage II and III ingrown nails. MATERIAL AND METHODS: The medical records of patients undergoing matrix cauterization with 10% NaOH or 88% phenol were evaluated. The primary outcome measure was the lack of recurrences on long-term follow-up. The secondary outcome measures were complete healing duration, patient-reported pain scores, and adverse effects related to the procedure. RESULTS: Enrolled in this study were 62 ingrown toenail sides treated with 10% NaOH and 56 ingrown toenail sides treated with 88% phenol. The mean follow-up duration was 25.17 months. Recurrence was observed in four nail sides of the NaOH group (%6.45) and three nail sides of the phenol group (%5.35). The difference between the recurrence rates did not reach statistical significance. Patients treated with both methods were free of pain on the post-procedural tenth day. The visual analog scale pain scores and complete healing duration were similar between the two groups (p>0.05). CONCLUSION: In a large group with long-term follow-up results, the short-term and long-term post-operative treatment outcomes were similar between the one-minute applications of 10% NaOH versus 88% phenol groups.

KH906, a recombinant human VEGF receptor fusion protein, is a new effective topical treatment for corneal neovascularization.

PURPOSE: The purpose of the current study was to investigate the effect of topical administration of KH906 on corneal neovascularization (NV). METHODS: To induce corneal neovascularization, chemical cauterization of the corneas of the right eyes of forty-eight New Zealand white rabbits was performed by touching the central cornea with an 8-mm-diameter NaOH-soaked Whatman filter paper for 60 s. On the next day after modeling, the rabbits were randomly and equally divided into six groups: PBS control group, 0.1% dexamethasone group, 10 mg/ml Avastin group, 5 mg/ml KH906 group, 10 mg/ml KH906 group, and 20 mg/ml KH906 group. The rabbits in the six groups received topical administration of 50 µl of the different solutions on the cornea four times per day for 14 days. Corneal neovascularization was analyzed by slit-lamp biomicroscopy 10 and 14 days after chemical cauterization. Corneal fluorescein staining was performed to evaluate the extent of corneal epithelial defect on the 7th, 10th, and 14th days. The VEGF level of the cornea was evaluated by ELISA assay. RESULTS: On the 10th and 14th days after chemical cauterization, the length of the longest new vessel and the areas of corneal neovascularization in all KH906-treated groups were significantly reduced compared to those of the PBS-treated group (p<0.05). The VEGF level of the cornea in all KH906-treated groups was significantly decreased compared to that of the PBS-treated group (p<0.05). Corneal fluorescein staining showed that KH906 had no effect on corneal epithelial healing. CONCLUSIONS: Topical administration of KH906 significantly inhibited alkali burn-induced corneal neovascularization in rabbits. The new eye drops of KH906 may have a broad application for human corneal neovascularization in the near future.

A robust model for simultaneously inducing corneal neovascularization and retinal gliosis in the mouse eye.

PURPOSE: To develop an animal model for simultaneously eliciting corneal angiogenesis and retinal gliosis that will enable the assessment of inhibitor efficacy on these two pathological processes in separate anatomic sites of the ocular globe. METHODS: Four to six week-old mice in a C57BL/6J background were anesthetized and 0.15 N NaOH was applied to the cornea, followed by mechanical scraping of the epithelium from limbus and central cornea. After this injury, mice were treated with vehicle or with an inhibitor (withaferin A [WFA]), which were delivered by intraperitoneal injection, to assess the pharmacological effects on angiogenesis and/or gliosis. Mice were sacrificed after 14 days and tissues (corneas and retinas) were prepared for analysis of corneal neovascularization and retinal gliosis by immunohistochemistry and western blotting, respectively. This protocol was also suited for studying earlier disease end points, for assessment of drug dose efficacy or genetic influences and the entire procedure and this analysis was completed in 16-17 days. RESULTS: Both corneal angiogenesis and retinal gliosis were maximally sustained at fourteen days following chemical and mechanical injury of the cornea. 1) Injured corneas showed abundant CD31+ staining, with new blood vessels branching out from the limbus to the central cornea. WFA treatment potently inhibited corneal neovascularization. 2) Retinal gliosis in injured mice was associated with upregulated expression of glial fibrillary acidic protein (GFAP) that appeared as polymeric filaments and soluble forms expressed in reactive Müller glial cells. WFA treatment potently downregulated the expression of soluble and filamentous GFAP; the latter protein was fragmented. CONCLUSIONS: We have developed a mouse model for investigating retinal gliosis and corneal neovascularization. We used this model to demonstrate the simultaneous inhibitory effects of WFA on both of these disease processes. Retinal gliosis occurs in several major degenerative conditions of the eye, including age-related macular degeneration, where angiogenesis is also a prevailing pathological feature. Thus, inhibitors of both gliosis and angiogensis used as combination therapy are currently being explored for treatment of such complex diseases. The model presented here affords a very simple preclinical assay for screening combination of drugs or polypharmacological agents and reduces the numbers of animals because of the different anatomic sites of these pathologies. Finally, given that endogenous mediators elicit angiogenesis and gliosis in this model, the combination of genetics and pharmacology can be exploited to study drug mechanisms and for target validation in vivo.

Combined treatment with antioxidants and immunosuppressants on cytokine release by human peripheral blood mononuclear cells - chemically injured keratocyte reaction.

PURPOSE: To investigate the effect of antioxidants and immunosuppresants on mixed peripheral blood mononuclear cells (PBMC) - chemically injured keratocytes reaction (MLKR). METHODS: The PBMC stimulation assay was performed using chemically injured keratocytes treated with 0.05 N NaOH for 90 s (MLKR). MLKR were treated with various drugs including rapamycin, dexamethasone, mycophenoleic acid (MPA), alpha lipoic acid (ALA), and N-acetyl cysteine (NAC). Matrix metalloprotease-9 (MMP-9), transforming growth factor-beta 1 (TGF-ß1), interleukin-6 (IL-6), and macrophage migration inhibitory factor (MIF) secretion profiles of activated PBMCs stimulated by NaOH-treated keratocytes were determined by ELISA. RESULTS: Anti-oxidants as well as immunosuppressants suppressed PBMC proliferation. MMP-9 levels were lower in antioxidants group. IL-6 levels decreased in dexamethasone group and anti-oxidants group. Combination of immunosuppressants and antioxidants suppressed more PBMC proliferation except for rapamycin + ALA group, suppressed MMP-9 production except for MPA + ALA group, decreased IL-6 levels and increased MIF levels except for rapamycin + ALA group. TGF-ß1 levels were elevated in rapamycin group and rapamycin + ALA group. CONCLUSIONS: Cytokine production was different depending on combination of drugs.Our results suggest that the different drugs should be selected for treatment according to the phases of corneal chemical burn.

NaOH-induced Crohn's colitis in rats: a novel experimental model.

AIM: Several models of experimental ulcerative colitis have been previously reported. To date, only one model of Crohn's colitis that was induced by trinitrobenzene sulfonic acid has been described. MATERIALS AND METHODS: Twenty-one male albino rats were divided into three groups: group I: sham control group (n = 7), group II: acetic acid group (n = 7), group III: NaOH group (n = 7). On the day of induction, all rats were lightly anesthetized with intramuscular ketamine (8 mg/kg). A 6F plastic catheter was inserted rectally until the tip was 5 cm proximal to the anus. Then, 2 ml of 0.9% saline, 2 ml of 4% acetic acid, and 2 ml of 6.25% NaOH was administered to groups I, II, and III, respectively. All rats were sacrificed 5 days after colitis induction. The distal colon segment was assessed macroscopically and microscopically. In addition, malondialdehyde (MDA) and nitric oxide (NO) levels of the colonic tissue and changes in body weight were measured. RESULTS: Macroscopic and microscopic examinations of colonic tissue samples showed morphological similarities to human Crohn's disease (CD). The MDA and NO levels of the colonic tissues were significantly higher in the NaOH group compared to the acetic acid and sham control groups (P = 0.001). CONCLUSION: NaOH may be used to induce Crohn's colitis as an experimental model.

Determining the effect of ocular chemical injuries on topical drug delivery.

Ocular chemical injuries (OCIs) commonly cause ocular damage and visual loss and treatment uses topical therapies to facilitate healing and limit complications. However, the impact of chemical injury on corneal barrier function and treatment penetration is unknown. Therefore, the aim of this study was to determine the effect of OCI on drug penetration and absorption. Porcine corneal explants were used to assess histological damage, electrical resistance, and the trans-corneal penetration/corneal adsorption of reference compounds (sodium fluorescein and rhodamine B) and dexamethasone. Corneal explants were injured with either 1 M sulfuric acid, or 1 M sodium hydroxide. Dexamethasone penetration was measured using high-performance liquid chromatography (HPLC) and that of fluorescein and rhodamine using fluorescence. Dexamethasone corneal adsorption was measured using enzyme-linked immunoabsorbant assay (ELISA). Both acid and alkaline injuries reduced trans-corneal electrical resistance. NaOH injury increased hydrophilic fluorescein penetration (NaOH 8.59 ± 1.50E-05 cm.min-1 vs. Hanks' Balanced Salt Solution (HBSS) 1.64 ± 1.01E-06 cm.min-1) with little impact on hydrophobic rhodamine B (1 M NaOH 6.55 ± 2.45E-04 cm.min-1 vs. HBSS 4.60 ± 0.972E-04 cm.min-1) and dexamethasone penetration (1 M NaOH 3.00 ± 0.853E-04 cm.min-1 vs. HBSS 2.69 ± 0.439E-04 cm.min-1). By contrast, H2SO4 decreased trans-corneal penetration of hydrophilic fluorescein (H2SO4 1.16 ± 14.2E-07 cm.min-1) and of hydrophobic dexamethasone (H2SO4 1.88 ± 0.646E-04 cm.min-1) and rhodamine B (H2SO4 4.60 ± 1.42E-05 cm.min-1). Acid and alkaline OCI differentially disrupted the corneal epithelial barrier function. Acid injury reduced penetration of hydrophobic dexamethasone and rhodamine B as well as hydrophilic fluorescein, which may translate clinically into reduced drug penetration after OCI, while alkaline injury increased fluorescein penetration, with minimal effect on dexamethasone and rhodamine B penetration.

Effect of Topical Instillation of Pegaptanib Sodium Upon Inflammatory Corneal Neovascularization in Rabbits.

Purpose: To evaluate the effect of topical instillation of pegaptanib sodium upon inflammatory angiogenesis induced in the rabbit cornea by alkaline cauterization. Methods: Inflammatory angiogenesis was induced by alkaline (sodium hydroxide) cauterization in the corneas of 29 male New Zealand rabbits. The animals were divided into 4 groups: a control group treated with 0.5% carboxymethylcellulose sodium eye drops, a group treated with 1.0% prednisolone acetate eye drops, a group treated with 0.5% pegaptanib sodium diluted in 15 mL 0.5% carboxymethylcellulose sodium, and a group treated with 1.0% pegaptanib sodium diluted in 15 mL 0.5% carboxymethylcellulose sodium. After cauterization, eye drops were administered every 12 hours for 21 days. The animals were evaluated every 3 days after cauterization, and the newly formed vessels were quantified from photographs. The treatment effectiveness was analyzed with 3 parameters of antiangiogenic response: neovascularization area (NA), total vascular length (TVL), and number of blood vessels (BVN). Results: Average NA, TVL, and BVN values were significantly higher in both pegaptanib groups than in the prednisolone group. A nonstatistically significant reduction in parameters on days 18 and 21 was the minimum achieved in both pegaptanib groups. The efficacy of the treatments in relation to the control was significantly greater in the prednisolone group than in the 0.5% pegaptanib group or the 1.0% pegaptanib group (P < 0.001). Conclusion: Topical instillation of 0.5% and 1.0% pegaptanib sodium diluted in 15 mL 0.5% carboxymethylcellulose sodium had no inhibitory effect on corneal neovascularization in this rabbit model.

A cross-linked hyaluronan gel accelerates healing of corneal epithelial abrasion and alkali burn injuries in rabbits.

OBJECTIVE: To evaluate the efficacy of a chemically modified and cross-linked derivative of hyaluronan (CMHA-SX) for treatment of corneal epithelial abrasion and standardized alkali burn injuries. ANIMALS: Twelve female New Zealand white rabbits in two groups were used. PROCEDURES: Bilateral 6-mm diameter corneal epithelial abrasions were made in each of six rabbits in one group and 6-mm standardized alkali burn injuries were made in the second group. A 1% CMHA-SX formulation was applied topically four times per day in right eye of each rabbit for 1 week, and phosphate buffered saline (PBS) was placed in left (control) eye of each rabbit. The wound size was determined by staining with 1% fluorescein and photographed at the slit lamp with a digital camera at 0, 1, 2, 3 days postoperatively in the first group and 0, 1, 2, 3, 7, 12 days in the second group. Rabbit corneas were collected for histological examination on day 7 in the first group and day 12 in the second group. RESULTS: Closure of corneal wound in the abrasion model was complete in the CMHA-SX treated eye by 48 h. The wound closure rate and thickness of the central corneal epithelium in the CMHA-SX treated group was greater than in control eyes for both the abrasion and alkali burn injuries. Moreover, the CMHA-SX treated cornea exhibited better epithelial and stromal organization than the untreated control cornea. CONCLUSIONS: Chemically modified and cross-linked derivative of hyaluronan improved corneal wound healing and could be useful for treating noninfectious corneal injuries.

Characterization of non-linear mechanical behavior of the cornea.

The objective of this study was to evaluate which hyperelastic model could best describe the non-linear mechanical behavior of the cornea, in order to characterize the capability of the non-linear model parameters to discriminate structural changes in a damaged cornea. Porcine corneas were used, establishing two different groups: control (non-treated) and NaOH-treated (damaged) corneas (n = 8). NaOH causes a chemical burn to the corneal tissue, simulating a disease associated to structural damage of the stromal layer. Quasi-static uniaxial tensile tests were performed in nasal-temporal direction immediately after preparing corneal strips from the two groups. Three non-linear hyperelastic models (i.e. Hamilton-Zabolotskaya model, Ogden model and Mooney-Rivlin model) were fitted to the stress-strain curves obtained in the tensile tests and statistically compared. The corneas from the two groups showed a non-linear mechanical behavior that was best described by the Hamilton-Zabolotskaya model, obtaining the highest coefficient of determination (R2 > 0.95). Moreover, Hamilton-Zabolotskaya model showed the highest discriminative capability of the non-linear model parameter (Parameter A) for the tissue structural changes between the two sample groups (p = 0.0005). The present work determines the best hyperelastic model with the highest discriminative capability in description of the non-linear mechanical behavior of the cornea.

(-)-Epigallocatechin-3-gallate, reduces corneal damage secondary from experimental grade II alkali burns in mice.

BACKGROUND: Since recent reports have shown that (-)-Epigallocatechin-3-gallate (EGCG) could be used for treating proliferative and inflammatory disorders, we explored its use for the management of corneal chemical burns. MATERIALS AND METHODS: Initially, EGCG was assayed on the rabbit corneal epithelial cell line RCE1(5T5) to establish the best testing conditions, and to avoid unwanted outcomes in the experimental animals. Then, we studied its effects on cell proliferation, cell cycle progression and cell differentiation. Afterwards, we instilled EGCG in experimental grade II corneal alkali burns in mice, three times a day up to 21days, and evaluated by slit lamp examination and histological sections of corneal epithelial, corneal endothelial and stromal edema, as well as the presence of inflammatory cells and neovascularization. RESULTS: EGCG reduced cell growth and led to a decline in the proportion of proliferative cells in a concentration dependent manner. At 10µM, EGCG promoted cell differentiation, an effect not related with apoptosis or cytotoxicity. When 10µM EGCG was instilled in corneal alkali burns in mice three times a day up to 21days, EGCG significantly reduced corneal opacity and neovascularization. The improved clinical appearance of the cornea was associated to a controlled epithelial growth; epithelial morphology was similar to that observed in normal epithelium and contrasted with the hyperproliferative, desquamating epithelium observed in control burn wounds. EGCG reduced corneal, stromal and endothelial edema, and wound inflammation. CONCLUSION: This work constitutes the first evidence for the use of EGCG in the acute phase of a corneal alkali burn, representing a possible novel alternative to improve patient outcomes as an add-on therapy.

Evaluation of 6 years use of sodium hydroxide solution to clear partially occluded central venous catheters.

BACKGROUND & AIMS: Central venous catheter occlusion is a frequently occurring complication during home parenteral nutrition (HPN). The aim of the study was to investigate the effectiveness of sodium hydroxide (NaOH) administration to clear an occluded central venous catheter especially in HPN. METHOD: Retrospective study to the use of NaOH in partially occluded central venous catheters. About 45 patients with HPN treated in the Academic Medical Center of the University of Amsterdam (AMC) were included in this study between January 1997 and April 2003. Excluded from the study were patients under the age of 18 at the start of HPN and/or patients who use parenteral nutrition for less than 3 months. Partial catheter occlusion was defined as a spontaneous flow less than 60 drops/min. RESULTS: In total, 130 occlusions were registered in 29 HPN patients. The other 16 HPN patients did not report any occlusion. The incidence of occlusions in fat containing total parenteral nutrition (TPN) was 1 occlusion in 167 feeding days. TPN without fat showed only one occlusion (incidence 1 in 7126 feeding days). The use of a lipid emulsion proved an important risk factor for catheter occlusion in this study (P<0.05, RR=43). Ninety-five central venous catheter occlusions were treated with NaOH 0.1M. The remaining occlusions were total or mechanical occlusions making NaOH treatment impossible. In 73 out of 95 partial occlusions treatment with NaOH was effective (P<0.05). Using NaOH extended the use of 32 catheters (range 7-1592 days, mean 328). Twenty-one out of 32 catheters could be used for more than 3 months after using NaOH (P<0.05). CONCLUSION: We conclude that perfusion of a partial occluded central venous catheter (defined as 25-60 drops/min) used for parenteral nutrition with 0.1N NaOH is safe and shows a significant long term improvement in catheter care, by preventing total occlusion and operative removal.

A bio-mathematical model of time prediction in corneal angiogenesis after alkali burn.

BACKGROUND: The determination of angiogenesis time is the key prerequisite to obtaining a balance between valid repair and excessive angiogenesis in wound healing. The aim of the investigation was to establish a bio-mathematical model predicting corneal angiogenesis time after alkali burn by back propagation neural network (BP neural network). METHODS: The corneas of mice in 24 groups were burned by 0.01 mol/l NaOH. Five mice in each group were sacrificed at 6h after alkali burn. The expression levels of vegf and tsp2, determined by real-time quantitive PCR, were used as input vectors in BP neural network. Meanwhile, the corneal angiogenesis of other mice, inspected every 3h in 24 groups till the angiogenesis time were determined, served as output vectors. The data of 18 groups were randomly chosen for network adaptation while that of other 6 groups for simulation forecasting with functions of minmax (), postreg, prepca, trapca, respectively. RESULTS: A bio-mathematical model of two-level BP neural network was established, for its purpose to predict the angiogenesis time through the expression values of vegf and tsp2. The performance index (0.00999996) was smaller than the target value (0.01) after adapting 36,557 times and the accuracy rate of this predict system was 83.33%. Furthermore, the ideal regression line and the optimization regression line were almost coincident (R=0.988 in network adaptation and R=0.793 in simulation forecasting). CONCLUSIONS: The investigation indicated that the bio-mathematical model had available performance of simulation and forecasting. It might provide a novel method to solve clinical problems.

Corrosive esophageal injuries in children. A shortlived experience in Sierra Leone.

OBJECTIVE: Children with caustic ingestions in developing countries are often treated at home, sometimes by traditional healers, or are referred, frequently late, to tertiary hospitals, which only seldom offer adequate endoscopic and dilatation facilities. Therefore, when dilatations are performed, the stricture is often already well established, making dilatation more difficult. The aim of this paper is to report our experience in the management of corrosive injuries in a group of children of Sierra Leone, all complaining accidental ingestion of caustic soda, many of them treated months after the ingestion. METHOD: We considered all children admitted after corrosive ingestion, from November 2001 to November 2005, to the "Emergency" Surgical Center in Goderich-Freetown, Sierra Leone. In December 2005 the hospital was supplied with endoscopes and dilatation devices. The children still followed up clinically were recalled to submit them to an endoscopic follow-up and to a dilatation, if needed. RESULTS: Forty children were admitted (mean age: 4.5 years): 16 (group A) after an esophageal perforation during dilatation performed elsewhere (death rate: 56%). Twenty-four children (group B) were observed after ingestion, 58% being submitted to a surgical gastrostomy. Death rate after ingestion was nil. The mean interval between ingestion and endoscopy was 8.8 months. Fifty-three dilatations were carried out in 17 children over a 3 months period. We report three perforations (17.6%) and a death rate of 5.8% (1/17). Two patients were lost to follow-up. Three patients (17.6%) did not show any improvement. Four children complained recurrent dysphagia after the first dilatation cycle. Overall, 10 children (58.8%) showed a clear-cut improvement at 6 months. CONCLUSIONS: The majority of treated strictures were late, therefore difficult to dilate and at higher risk of perforation. Dilatation with Savary bougies seems safer than with balloon catheters. Recurrent strictures and a long-term dilatation treatment should be expected. Retrograde dilatations through gastrostomies should be the preferred method of treatment and surgical gastrostomies should be performed without hesitation. Esophageal replacement is unlikely in these countries, except in very few referral centres. Therefore, any effort should be made to treat caustic strictures by timely dilatation programs.

Kastle-Meyer blood test reagents are deleterious to DNA.

The Kastle-Meyer (KM) test is a quick and easy chemical test for blood used in forensic analyses. Two practical variations of this test are the KM-rub (indirect) test and the more sensitive KM-direct test, the latter of which is performed by applying reagents directly to a suspected blood stain. This study found that sodium hydroxide present in the KM reagents eliminated the potential to generate a DNA profile when applied directly to small quantities of blood. A modified approach to the KM-rub test that increases its sensitivity is presented as a method to replace destructive KM-direct testing.