An ex vivo comparison of cuffed endotracheal tubes and self-sealing baffled endotracheal tubes.

AIMS To compare cuffed silicone endotracheal tubes with self-sealing baffled silicone endotracheal tubes in an ex vivo canine tracheal model, to determine whether the tubes differed in their maintenance of a seal and their effectiveness in removing fluid from the tracheal lumen, and whether the self-sealing endotracheal tubes would release pressure when a closed anaesthetic circuit reached ≥30 cm H2O. METHODS Twelve cadaver tracheae were randomly selected to be intubated with either cuffed or self-sealing baffled endotracheal tubes. To test tracheal seal efficacy, the tracheae were positioned vertically, 5 mL of water was instilled proximal to the tube cuff or baffles and they were monitored for leakage at 0, 15, 30, 45, and 60 minutes, recording the total volume leaked. To test fluid removal at extubation, the tracheae were intubated, then 5.6 g of 60% barium sulphate suspension was instilled proximal to the seal and left undisturbed for 5 minutes. The tubes were then extubated, with the cuffed endotracheal tubes being partially deflated before extubation, and the amount of barium recovered was weighed. These procedures were repeated on the same tracheae using the other endotracheal tubes. To test whether self-sealing baffled endotracheal tubes would release pressure at ≥30 cm H2O, the tracheae were intubated, connected to an anaesthetic machine and pressurised to 30 cm H2O for 5 minutes and then 50 cm H2O for 5 minutes. Release of pressure was defined as a decrease in pressure within the closed anaesthetic circuit. RESULTS More cuffed (7/12) than baffled (0/12) endotracheal tubes leaked water after 60 minutes (p=0.016). The mean amount of barium removed by the self-sealing baffled endotracheal tubes (4.9 (95% CI=3.8-4.4) g) was greater than that removed by the partially deflated cuffed endotracheal tubes (0.4 (95% CI=0.14-0.66) g) (p<0.001). None of the self-sealing baffled endotracheal tubes released pressure at ≥30 cm H2O in a closed anaesthetic circuit. CONCLUSIONS AND CLINICAL RELEVANCE Self-sealing baffled endotracheal tubes were more effective than cuffed endotracheal tubes at both preventing fluid leakage at the tracheal seal and removing fluid from the lumen of the trachea in cadaver tracheae. However they did not release pressure when the closed-circuit system was at ≥30 cm H2O in a canine cadaver model. The self-sealing baffled endotracheal tubes may be a suitable substitute for cuffed endotracheal tubes.

Latitudinal variation of freeze tolerance in intertidal marine snails of the genus Melampus (Gastropoda: Ellobiidae).

Abstract Low temperatures limit the poleward distribution of many species such that the expansion of geographic range can only be accomplished via evolutionary innovation. We have tested for physiological differences among closely related species to determine whether their poleward latitudinal ranges are limited by tolerance to cold. We measured lower temperature tolerance (LT50) among a group of intertidal pulmonate snails from six congeneric species and nine locales. Differences in tolerance are placed in the context of a molecular phylogeny based on one mitochondrial (cytochrome oxidase subunit I) and two nuclear (histone 3 and a mitochondrial phosphate carrier protein) markers. Temperate species from two separate lineages had significantly lower measures of LT50 than related tropical species. Range differences within the temperate zone, however, were not explained by LT50. These results show that multiple adaptations to cold and freezing may have enabled range expansions out of the tropics in Melampus. However, northern range limits within temperate species are not governed by cold tolerance alone.

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma.

AIMS: Vascular perfusion may be impaired in primary open-angle glaucoma (POAG); thus, we evaluated a panel of markers in vascular tone-regulating genes in relation to POAG. METHODS: We used Illumina 660W-Quad array genotype data and pooled P-values from 3108 POAG cases and 3430 controls from the combined National Eye Institute Glaucoma Human Genetics Collaboration consortium and Glaucoma Genes and Environment studies. Using information from previous literature and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we compiled single-nucleotide polymorphisms (SNPs) in 186 vascular tone-regulating genes. We used the 'Pathway Analysis by Randomization Incorporating Structure' analysis software, which performed 1000 permutations to compare the overall pathway and selected genes with comparable randomly generated pathways and genes in their association with POAG. RESULTS: The vascular tone pathway was not associated with POAG overall or POAG subtypes, defined by the type of visual field loss (early paracentral loss (n=224 cases) or only peripheral loss (n=993 cases)) (permuted P≥0.20). In gene-based analyses, eight were associated with POAG overall at permuted P<0.001: PRKAA1, CAV1, ITPR3, EDNRB, GNB2, DNM2, HFE, and MYL9. Notably, six of these eight (the first six listed) code for factors involved in the endothelial nitric oxide synthase activity, and three of these six (CAV1, ITPR3, and EDNRB) were also associated with early paracentral loss at P<0.001, whereas none of the six genes reached P<0.001 for peripheral loss only. DISCUSSION: Although the assembled vascular tone SNP set was not associated with POAG, genes that code for local factors involved in setting vascular tone were associated with POAG.

Effects of caffeinated coffee consumption on intraocular pressure, ocular perfusion pressure, and ocular pulse amplitude: a randomized controlled trial.

PURPOSE: To examine the effects of caffeinated coffee consumption on intraocular pressure (IOP), ocular perfusion pressure (OPP), and ocular pulse amplitude (OPA) in those with or at risk for primary open-angle glaucoma (POAG). METHODS: We conducted a prospective, double-masked, crossover, randomized controlled trial with 106 subjects: 22 with high tension POAG, 18 with normal tension POAG, 20 with ocular hypertension, 21 POAG suspects, and 25 healthy participants. Subjects ingested either 237 ml of caffeinated (182 mg caffeine) or decaffeinated (4 mg caffeine) coffee for the first visit and the alternate beverage for the second visit. Blood pressure (BP) and pascal dynamic contour tonometer measurements of IOP, OPA, and heart rate were measured before and at 60 and 90 min after coffee ingestion per visit. OPP was calculated from BP and IOP measurements. Results were analysed using paired t-tests. Multivariable models assessed determinants of IOP, OPP, and OPA changes. RESULTS: There were no significant differences in baseline IOP, OPP, and OPA between the caffeinated and decaffeinated visits. After caffeinated as compared with decaffeinated coffee ingestion, mean mm Hg changes (± SD) in IOP, OPP, and OPA were as follows: 0.99 (± 1.52, P<0.0001), 1.57 (± 6.40, P=0.0129), and 0.23 (± 0.52, P<0.0001) at 60 min, respectively; and 1.06 (± 1.67, P<0.0001), 1.26 (± 6.23, P=0.0398), and 0.18 (± 0.52, P=0.0006) at 90 min, respectively. Regression analyses revealed sporadic and inconsistent associations with IOP, OPP, and OPA changes. CONCLUSION: Consuming one cup of caffeinated coffee (182 mg caffeine) statistically increases, but likely does not clinically impact, IOP and OPP in those with or at risk for POAG.

Effect of gabapentin-like compounds on development and maintenance of morphine-induced conditioned place preference.

RATIONALE: Psychological dependence to the opioid analgesic morphine is attributable to the rewarding properties of the drug, and its evolution can be divided into two distinct phases: development and maintenance. Both phases can be studied using conditioned place preference (CPP). OBJECTIVES: To determine whether the two phases can be influenced by pre-treatment with gabapentin-like compounds. METHODS: CPP to morphine was used to demonstrate the rewarding properties of morphine in the presence or absence of gabapentin-like compounds. In-vivo microdialysis in the nucleus accumbens was used to determine the effects of gabapentin or pregabalin on morphine-induced dopamine release. RESULTS: Pretreatment with either gabapentin (10-100 mg/kg p.o.) or pregabalin (3-30 mg/kg p.o.) attenuated CPP induced by a submaximal dose of morphine (0.75 mg/kg). Neither gabapentin nor pregabalin had any effect alone in the CPP test. Both gabapentin-like compounds blocked the effect of morphine (0.75 mg/kg s.c.) to increase the release of dopamine in the nucleus accumbens. Studies of the maintenance of CPP to morphine showed CPP was maintained for at least 4 days after the initial test. In a second experiment, it was found that pregabalin (injected once, 24 h after CPP had been demonstrated) was able to reverse morphine-induced CPP. CONCLUSIONS: Neither gabapentin nor pregabalin induced CPP, but both compounds blocked the development of CPP to morphine and also blocked morphine's effects on dopamine release. Furthermore, pregabalin blocked the maintenance of morphine-induced CPP. It is concluded that gabapentin-like compounds, which have no intrinsic rewarding properties, may have some therapeutic use in the treatment of opioid dependence.

Fibromyalgia syndrome improved using a mostly raw vegetarian diet: an observational study.

BACKGROUND: Fibromyalgia engulfs patients in a downward, reinforcing cycle of unrestorative sleep, chronic pain, fatigue, inactivity, and depression. In this study we tested whether a mostly raw vegetarian diet would significantly improve fibromyalgia symptoms. METHODS: Thirty people participated in a dietary intervention using a mostly raw, pure vegetarian diet. The diet consisted of raw fruits, salads, carrot juice, tubers, grain products, nuts, seeds, and a dehydrated barley grass juice product. Outcomes measured were dietary intake, the fibromyalgia impact questionnaire (FIQ), SF-36 health survey, a quality of life survey (QOLS), and physical performance measurements. RESULTS: Twenty-six subjects returned dietary surveys at 2 months; 20 subjects returned surveys at the beginning, end, and at either 2 or 4 months of intervention; 3 subjects were lost to follow-up. The mean FIQ score (n = 20) was reduced 46% from 51 to 28. Seven of the 8 SF-36 subscales, bodily pain being the exception, showed significant improvement (n = 20, all P for trend < 0.01). The QOLS, scaled from 0 to 7, rose from 3.9 initially to 4.9 at 7 months (n = 20, P for trend 0.000001). Significant improvements (n = 18, P < 0.03, paired t-test) were seen in shoulder pain at rest and after motion, abduction range of motion of shoulder, flexibility, chair test, and 6-minute walk. 19 of 30 subjects were classified as responders, with significant improvement on all measured outcomes, compared to no improvement among non-responders. At 7 months responders' SF-36 scores for all scales except bodily pain were no longer statistically different from norms for women ages 45-54. CONCLUSION: This dietary intervention shows that many fibromyalgia subjects can be helped by a mostly raw vegetarian diet.

Isolation and identification of an ice-nucleating bacterium from the gills of the intertidal bivalve mollusc Geukensia demissa.

In the fall, freeze tolerant intertidal invertebrates usually produce ice-nucleating proteins that are secreted into the hemolymph. These proteins help protect against freeze damage by insuring that ice formation is limited to extracellular spaces. Geukensia demissa, a freeze tolerant, salt marsh bivalve mollusc was examined for the presence of ice nucleating proteins. The ice-nucleating temperature (INT) of the hemolymph was not significantly different from artificial seawater of the same salinity indicating the lack of an ice nucleating protein in the hemolymph. The palial fluid did have an elevated INT, indicating the presence of an ice nucleator. The INT of the palial fluid was significantly reduced by boiling and filtration through a 0.45-&mgr;m filter. High INT was also observed in the seawater associated with the bivalves, and was demonstrated in water samples collected from salt marshes but not sand and pebble beaches. Moreover, the INT of water samples collected from a salt marsh decreased in the summer. All of these data suggest that the ice-nucleating agents in the hemolymph and the seawater are ice-nucleating bacteria. One species of ice-nucleating bacteria, Pseudomonas fulva was isolated from the gills of Geukensia. These bacteria could perform the same function as hemolymph ice-nucleating proteins by limiting ice formation to extracellular compartments.

Prioritizing back injury risk in hospital employees: application and comparison of different injury rates.

To identify high risk areas for back injury in a large teaching hospital, we calculated standard injury rates and newly developed composite statistics for nursing and non-nursing work groups. Data were extracted from the hospital's workers' compensation database. The hospital-wide total injury rate was 4.6 reports per 100 full-time equivalents (FTE); Compensation Case Rate, 1.4 cases per 100 FTE; Compensation Severity Rate, 76 days lost per 100 FTE; and the Cost Rate, $3742 per 100 FTE. The Total Injury Reports Rate for nursing varied from 14.2 per 100 FTE for Intensive Care Unit (ICU) Nursing to 3.8 per 100 FTE for Pediatric Nursing. Non-nursing areas also demonstrated increased rates for back injury. Individual statistical rates ranked areas differently in risk, whereas composite statistical measures consistently ranked ICU Nursing, Buildings and Grounds, and Orthopedics/Neurological Nursing as the top three. Patient handling was the precipitating event in the majority of nursing back injuries, indicating the need for ergonomic intervention. The use of combined statistical measures provided a more integrative measure for describing and following back injury risk over time.

Transitional duty. An overview of program management and placement process.

Transitional duty is an effective means to return employees to work after an injury or illness. Provision of transitional duty may facilitate earlier return to work. It also helps in retaining an experienced work force, and decreases disability related costs. The occupational and environmental health nurse plays a major role in developing and maintaining a transitional duty program. Essential to programmatic responsibility is the ability to determine organizational culture, involve key stakeholders, and develop a program proposal that "sells" the program to a variety of customers. The ability to consistently evaluate and demonstrate program outcomes, once formal support is attained, is crucial to continued program support. The transitional duty placement process is a vital component of a comprehensive disability program and ensures employees are identified and placed appropriately according to their functional capacity. Routine evaluation of employees on transitional duty is essential to allow for progressive placement. The nurse plays a vital part in counseling and supporting employees and supervisors involved in the transitional duty process.

Varicella vaccination. An overview for the occupational health nurse.

1. Varicella-zoster virus is highly communicable. Non-immune adults are susceptible to infection and, if infected, have increased risk of complications. 2. Adult varicella infection poses significant economic loss for the infected employee and potentially for exposed coworkers and the employer. Health care employers also must be concerned about transmission of varicella infection to clients. 3. Varicella vaccine is now available, well tolerated, and prevents infection in approximately 94% of vaccinees. The occupational health nurse needs to consider varicella vaccination for employees susceptible to infection.

Methods of prioritizing and measuring occupational health risks utilizing hospital back injury data. Development of composite comparative statistics.

The employee health service of a Boston hospital wanted a method to prioritize the risk of occupational injury or illness among its employees as the first step in developing a comprehensive ergonomics program. Data from the safety office and workers' compensation third-party administrator (TPA) was combined with hospital payroll data to create rates that compared all work areas based on the common denominator of 100 full-time equivalents (FTE). Rates for four different aspects of injury experience were calculated: incidence of total reported injuries, incidence of serious injuries, level of severity of injuries, and cost. The use of these simple rates alone was inadequate to accurately prioritize risk. Because most work areas ranked differently from one rate scale to the next, it was unclear which, if any, single rate most accurately defined risk. Composite statistics that combined all of the rates were needed. The Composite Risk Indicator (CRI), the Average Relative Risk (ARR), and the Justified Average Relative Risk (JARR) were developed and examined for their utility. The JARR emerged as the best choice in this setting because it captured all available information about injury or illness experience and provided a meaningful single indicator of risk that could be followed over time.

Metabolism of Gemmules From the Freshwater Sponge Eunapius fragilis During Diapause and Post-Diapause States.

Post-diapause gemmules of the freshwater sponge Eunapius fragilis remained quiescent when maintained at 5°C. Germination occurred within 48 to 72 h following warming to 20°-23°C, culminating with the emergence of a new sponge from the collagenous capsule. Both heat dissipation and oxygen consumption climbed steadily during germination and eventually reached 600% of the starting values. By comparison, energy flow was much lower over the same period of time in diapausing gemmules, clearly demonstrating metabolic depression during diapause. The calorimetric:respirometric (CR) ratio increased significantly from -354 kJ/mol O2 to -541 kJ/mol O2 between hours 3.5 and 56.5 of germination, with an average value across this period of about -495 kJ/mol O2. The low CR ratio at hour 12.5 (-374 +/- 21; +/- 1 SE, n = 3) was statistically below the oxycaloric equivalent, which suggests that gemmules may have experienced hypoxia during the more than 3 months of storage at 5°C prior to experiments. The increase in metabolism during germination could be blocked by perfusing the gemmules with nitrogen-saturated medium (nominally oxygen free). Developing gemmules were able to survive oxygen limitation for several hours at least; during that time energy flow was depressed to 6% of normoxic values. During germination, the range of values was 3.5 to 4.0 nmol/mg protein for ATP, 0.2 to 0.4 nmol/mg protein for ADP, and 0.5 to 0.8 nmol/mg protein for AMP. Because ATP was high even before gemmules were warmed to room temperature, it is unlikely that levels were severely compromised during the diapause condition.

Carbohydrate Mobilization During Germination of Post-Diapausing Gemmules of the Freshwater Sponge Eunapius fragilis.

Post-diapausing gemmules of the freshwater sponge Eunapius fragilis were found to contain sorbitol and glycogen as their primary carbohydrates. The sorbitol probably acts to increase the tolerance of the gemmules to freezing and desiccation. During germination, average sorbitol levels--measured as micromoles of sorbitol per gram of fresh weight of gemmule tissue (µmol/gfw)--declined from a control value of 36 µmol/gfw to about 4 µmol/gfw. Concomitantly, average glycogen levels increased from a control value of 29 µmol/gfw to a steady-state level of 62 µmol/gfw. It is probable that glycogen is being synthesized at the expense of sorbitol. The breakdown of sorbitol was associated with an increase in the activity of sorbitol dehydrogenase from undetectable levels in dormant gemmules to a maximum of 0.2 µmol/ min · mg protein after 30 h of exposure to 20°C. Aldose reductase activity remained constant throughout germination. These data support the hypothesis that the decrease in sorbitol levels is the result of an increase in the rate of catabolism by sorbitol dehydrogenase. The total activity of glycogen synthase did not change during germination; however, the activity of glucose-6-phosphate-dependent glycogen synthase was about 18 times greater than the activity of glucose-6-phosphate-independent glycogen synthase. Total glycogen phosphorylase activity increased from about 1.6 nmol/min.mg protein to 3.6 nmol/min.mg protein during germination. At the same time, however, the percentage of glycogen phosphorylase a decreased from almost 100% to about 84%. This decrease would attenuate the apparent increase in activity. cAMP levels remained constant throughout germination. The observed changes in the level of glycogen in the gemmules are not simply due to changes in the activity of either glycogen phosphorylase or glycogen synthase.

Laryngeal reconstruction in children. Assessment of vocal quality.

During the past decade, the outcome of laryngotracheal reconstruction in children has improved substantially regarding airway patency. Now that we feel comfortable with airway results, attention should be directed toward vocal quality. The aims of this article are to present our evaluation process, which has been developed during the past 3 years, and our assessment of results. Six patients who underwent successful laryngotracheal reconstruction and could be examined preoperatively and postoperatively were studied. Information about disease and reconstruction techniques was recorded. Vocal quality assessment was done using psychoacoustic evaluation and objective techniques, including acoustic analysis. Children offer a specific challenge, especially when their chronological or developmental age is younger than 3 years. Objective assessment still lacks the ability of using cooperative patients, and adequate samples for acoustic analysis are difficult to obtain and standardize. Preoperative abnormalities continued to persist postoperatively. Laryngotracheal reconstruction is instrumental in making oral communication possible, but the vocal quality is disturbed in most patients.

Vocal quality of decannulated children following laryngeal reconstruction.

Laryngotracheal reconstruction with expansion surgery is a reliable method for treatment of laryngotracheal stenosis in children. It allows for decannulation of the patient and restoration of vocal communication. Previous information regarding vocal quality in these patients has been scant. Sixteen children who underwent successful laryngotracheal reconstruction were evaluated using a standardized voice assessment during each of the following: phoneme prolongation, counting, storytelling, and spontaneous conversation. Interjudge ratings were obtained to establish reliability. The location and severity of the laryngotracheal stenosis and the method of treatment were reviewed. Twelve children have a functional voice compared to six preoperatively. Overall, vocal parameters suggested a particular pattern consisting of a lower than optimal pitch and a restricted pitch range. Laryngotracheal reconstruction does make oral communication possible for children who would otherwise have persistent tracheotomy. However, vocal quality appears to be disturbed in most of the patients.

Mechanisms of interaction of amino acids with phospholipid bilayers during freezing.

In this study we compare the ability of various amino acids to protect small unilamellar vesicles against damage during freeze/thaw. Liposomes were composed of 75% palmitoyloleoyl phosphatidylcholine and 25% phosphatidylserine. Damage to liposomes frozen in liquid nitrogen and thawed at 20 degrees C was assessed by resonance energy transfer. Cryoprotection by numerous amino acids was compared in the presence and absence of 350 mM NaCl. The majority of amino acids with hydrocarbon side chains increased membrane damage during freeze/thaw regardless of the presence of salt. However, amino acids with hydrocarbon side chains of less than three carbons long, e.g. glycine, alanine, and 2-aminobutyric acid, were cryoprotective only in the presence of salt. We suggest that NaCl selectively increases the solubility of such amino acids, allowing them to act as cryoprotectants. In contrast, amino acids with side chains containing charged amine groups were cryoprotective regardless of the presence of salt. The degree of charge on the second amine group is shown to be important for cryoprotection by these molecules. We present evidence that suggests an interaction between the positively charged, second amine group of the amino acid, and the negatively charged phospholipid headgroup.

Long-term preservation of dried phosphofructokinase by sugars and sugar/zinc mixtures.

We have demonstrated that sugars and suger/zinc mixtures can be used to preserve the activity of dried phosphofructokinase (PFK) during long-term storage over CaSO4. After 9 weeks in the presence of either 200 mM sucrose or 200 mM trehalose little loss of PFK activity was noted, with almost 60% of the original prefreeze-dry activity recovered when samples were rehydrated. Even reducing sugars protected the dried enzyme throughout the entire storage period. Of the sugars tested, 200 mM lactose provided the most stability to PFK; at the end of the dry storage, over 80% of the initial activity was recovered. With either 200 mM maltose or 400 mM glucose, about 40% of the initial activity was recovered at the end of the experiment. With all the sugars tested, the addition of 0.6 mM Zn2+ to sugar/PFK mixtures enhanced the stability of the enzyme, and no long-term adverse effects of the metal ion on enzyme activity were noted.