An ergonomic evaluation of infant life jackets: Donning time & donning accuracy

Canada is considering the development of a new standard for infant/child life jackets. Eight currently available (approved and non-approved) infant/child life jackets were procured for evaluation. Fifty-six participants were chosen as a sample of convenience from the general public for testing. The life jackets were divided into two groups of four, which were donned on a soft infant manikin procured from the Red Cross. In 224 attempts at donning, only 43 (19%) attempts resulted in the life jacket being donned correctly in less than 1 min. Only one life jacket came close to a good design and passed the life jacket standard for donning time and accuracy. Failure rates were observed across all the participants irrespective of age, gender, experience with children and experience with recreational marine equipment. Accuracy and speed of donning the life jacket were hampered as the number of donning sub-tasks increased. It was concluded that it is possible to design a life jacket that can be donned correctly in under 1 min. The life jacket must be of simple, intuitive design and fall naturally into the anatomical shape of the child. A minimum number of ties, zips and clips should be used in the design, and if such connectors are used they should be color coded or of different shapes and sizes to avoid confusion.

Use of a patient linked data warehouse to facilitate diabetes trial recruitment from primary care

Recruitment into clinical trials from primary care may be difficult. Our aim was to use the Secure Anonymised Information Linkage (SAIL) databank to identify potential participants for two factitious trials. We identified 284 and 711 participants for each study (population=250,086). This method appears promising in identifying trial participants.

How much did cold shock and swimming failure contribute to drowning deaths in the fishing industry in British Columbia 1976-2002?

BACKGROUND

The Workers' Compensation Board of British Columbia requested a retrospective analysis of all fishermen's deaths from immersion in water in British Columbia.

AIMS

To identify the underlying cause of drowning and make recommendations to improve safety in the fishing industry.

METHOD

Eighty-nine inshore and offshore fishing accidents were analysed. Where possible, deaths were classified into the four stages of cold-water immersion: cold shock, swimming failure, hypothermia and post-rescue collapse. Other factors that led up to the drowning were also identified.

RESULTS

One hundred and thirty fishermen died from immersion between 1976 and 2002. One hundred and twenty-eight drownings were certified by the coroner as drowning or drowning/hypothermia and two were certified as cardiac event after immersion. The underlying causes of drownings were reclassified as: cold shock (5.4%), swimming failure (5.4%), hypothermia (5.4%), post-rescue collapse (0.8%), cardiac event (0.8%) and drowning/other (10%). In the remaining 72.2% of deaths, there was insufficient information to determine an underlying cause. All deaths occurred in water below 17.5 degrees C but 95% were in water less than 15 degrees C.

CONCLUSIONS

Immersion in water below 15 degrees C is dangerous and this should be emphasized on marine survival courses. Accident investigators, coroners and pathologists need a common checklist to record vital data. A recommended format is included as Supplementary data available at Occupational Medicine Online. Fishermen should be educated about the dangers of sudden, unexpected immersion in cold water. Consideration should be given to making marine survival courses mandatory for fishermen.

Fractalkine expression on human renal tubular epithelial cells: potential role in mononuclear cell adhesion

Fractalkine (CX3CL1) is a transmembrane molecule with a CX3C chemokine domain attached to an extracellular mucin stalk which can induce both adhesion and migration of leucocytes. Mononuclear cell infiltration at renal tubular sites and associated tubular epithelial cell damage are key events during acute renal inflammation following renal allograft transplantation. Using northern and Western blot analysis, we have demonstrated the expression of fractalkine message and protein by renal tubular epithelial cells in vitro. The expression was up-regulated by TNF-alpha, a key proinflammatory cytokine in acute rejection. Investigation of surface expression of fractalkine on cultured proximal tubular epithelial cells revealed only a subpopulation of positively staining cells. Immunohistochemistry revealed that only a proportion of tubules in renal allograft biopsies showed induction of fractalkine expression. Studies using a static model of adhesion demonstrated CX3CR1/fractalkine interactions accounted for 26% of monocytic THP-1 cell and 17% of peripheral blood natural killer cell adhesion to tubular epithelial cells, suggesting that fractalkine may have a functional role in leucocyte adhesion and retention, at selected tubular sites in acute renal inflammation. Thus, fractalkine blockade strategies could reduce mononuclear cell mediated tubular damage and improve graft survival following kidney transplantation.

Breath-holding ability of offshore workers inadequate to ensure escape from ditched helicopters

BACKGROUND

Following a helicopter ditching in water, the survival rate of individuals not mortally injured by the impact ranges from 50-85%. One possible cause for this low survival rate is that the crew and passengers cannot hold their breath underwater long enough to make the often difficult escape from an inverted and submerged helicopter.

METHODS

We investigated pulmonary function, breath-holding times in air (BHTa) and water (BHTw) of 228 students enrolled in offshore survival courses required to work in either the offshore petroleum industry or in military marine aviation. Comparisons were performed based on occupation, SCUBA experience, and smoking.

RESULTS

In 25 degrees C pool water, the overall BHTw ranged from 5.4 to 120 s with a median of 37 s. Of the 228 subjects, 34% had a BHTw less than the 28 s required for the complete evacuation of a Super Puma helicopter under ideal conditions. No significant differences in BHTw were observed based on either smoking history (Non-Smoker, 41.5 +/- 21.6 s; Smoker, 37.2 +/- 20.2 s) or occupation (Novice, 37.5 +/- 21.1 s; Offshore, 40.5 +/- 21.1 s; Military, 45.2 +/- 20.9 s). However, SCUBA-trained individuals had a significantly longer BHT, (47.4 +/- 21.6 s) than non-SCUBA (37.6 +/- 20.6 s), as well as a greater force vital capacity (FVC), BHTa, and subjective comfort in water.

CONCLUSIONS

It is concluded that the inability to breath-hold in emergency situations is a major contributor to the low survival rates of marine helicopter ditchings. Therefore, efforts must be made to both decrease escape times and to increase survival time underwater.

The basis for the development of a fuselage evacuation time for a ditched helicopter

HYPOTHESIS

When a helicopter ditches or crashes in water, unless the buoyancy bags are inflated, it commonly sinks inverted. Thus, crew and passengers must make an underwater escape. It is postulated that later passengers in the escape sequence do not have the breath-holding ability to conduct a successful escape, particularly if the water is cold. This contributes to the 20-50% mortality rate in survivable accidents.

METHODS

There were 132 immersed subject evaluations which were conducted in daylight and darkness to measure escape times from a helicopter underwater escape trainer, configured to the Super Puma, seated for 15 and 18 passengers. The subjects were highly experienced instructors or Navy clearance divers.

RESULTS

The time from when each subject's head disappeared underwater until each subject surfaced and total fuselage evacuation time were measured and any problems hampering escape were noted. Breath-holding for the last subject out ranged from 28 to 92 s. An emergency breathing system was used by a minimum of four subjects each time and a maximum of 11 subjects in one condition. The buoyancy of the survival suit was the principal component that hampered escape.

CONCLUSION

Breath-holding times were too long for the later subjects to escape without resorting to an EBS, in spite of the fact that they were highly trained. For regular crew and passengers flying over water, this would explain the high mortality, etc. Therefore, a new helicopter standard should be developed requiring fuselage design to accommodate total evacuation within 20 s from underwater. For current helicopters, where this cannot be achieved, passengers should be provided with some form of air supply, or, after ditching, the helicopter should be modified so that it will stay afloat on its side and retain an air space in the cabin.

Underwater disorientation as induced by two helicopter ditching devices

BACKGROUND

Spatial orientation is based on the integration of concordant and redundant information from the visual, vestibular, and somatosensory systems. When a person is submerged underwater, somatosensory cues are reduced, and vestibular cues are ambiguous with respect to upright or inverted position. Visual cues may be lost as a result of reduced ambient light. Underwater disorientation has been cited as one of the major factors that could inhibit emergency egress after a helicopter ditching into water. One countermeasure to familiarize aircrew with underwater disorientation is emergency egress training. This study examined the relative degree of underwater disorientation induced by the Modular Egress Training Simulator (METS) and the Shallow Water Egress Trainer (SWET).

METHODS

There were 36 healthy subjects (28 males and 8 females) who participated in the study. Underwater disorientation was quantified by measuring the deviation of subjective vertical-pointing from the gravitational vertical, time to egress, and subjective reports of disorientation and ease of egress. A repeated measure design was employed with seat position (SWET chair, METS window, and METS aisle) as the sole factor.

RESULTS

Subjective response data indicated that the degree of disorientation is rated significantly higher, and the ease of egress is rated worse from the two METS seat positions than from the SWET. This is supported by the findings that subjective vertical-pointing accuracy is worse in the METS seat positions than in the SWET (p < 0.01). The time to egress is longer from the two METS seat positions than from SWET (p < 0.01).

CONCLUSION

Our results indicate that the METS device is effective for inducing underwater disorientation as provoked by simulated helicopter ditching. disorientation, vestibular, subjective pointing.

Cholesterol oxidase: sources, physical properties and analytical applications

Since Flegg (H.M. Flegg, An investigation of the determination of serum cholesterol by an enzymatic method, Ann. Clin. Biochem. 10 (1973) 79-84) and Richmond (W. Richmond, The development of an enzymatic technique for the assay of cholesterol in biological fluids, Scand. J. clin. Lab. Invest. 29 (1972) 25; W. Richmond, Preparation and properties of a bacterial cholesterol oxidase from Nocardia sp. and its application to enzyme assay of total cholesterol in serum, Clinical Chemistry 19 (1973) 1350-1356) first illustrated the suitability of cholesterol oxidase (COD) for the analysis of serum cholesterol, COD has risen to become the most widely used enzyme in clinical laboratories with the exception of glucose oxidase (GOD). The use is widespread because assays incorporating the enzyme are extremely simple, specific, and highly sensitive and thus offer distinct advantages over the Liebermann-Burchard analytical methodologies which employ corrosive reagents and can be prone to unreliable results due to interfering substances such as bilirubin. Individuals can now readily determine their own serum cholesterol levels with a simple disposable test kit. This review discusses COD in some detail and includes the topics: (1) The variety of bacterial sources available; (2) The various extraction/purification protocols utilised in order to obtain protein of sufficient clarification (purity) for use in food/clinical analysis; (3) Significant differences in the properties of the individual enzymes; (4) Substrate specificities of the various enzymes; (5) Examples of biological assays which have employed cholesterol oxidase as an integral part of the analysis, and the various assay protocols; (6) New steroidal products of COD. This review is not a comprehensive description of published work, but is intended to provide an account of recent and current research, and should promote further interest in the application of enzymes to analytical selectivity.

Repellent and antifeedant activity of salicylic acid and related compounds against the biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae)

An artificial membrane, blood-feeding method was used to assess the repellent and antifeedant effects of derivatives of salicylic acid on the biting midge Culicoides impunctatus Goetghebeur. Trans-2-hydroxycyclohexanecarboxylic acid, 6-methylsalicylic acid, 2,6-dihydroxy-4-methylbenzoic acid, and salicyluric acid caused highly significant inhibition of feeding, with salicyluric acid performing significantly greater than the other compounds. Investigating the effects of alkyl substitution of salicylic acid, o-thymotic and o-cresotic acids were also effective. A pilot clinical trial using salicyluric acid indicated that it provided a protective effect and it was hypothesized that this may have resulted primarily from contact, because no significant repellent effects were shown for this compound in a microscope slide test, designed to demonstrate repellency with volatile compounds.

Evaluation of a new universal jettison mechanism for helicopter underwater escape

BACKGROUND

To date, there is no standard jettison mechanism for doors, windows, or hatches in ditched helicopters. A new Universal Escape Exit (UEE) has been invented and the performance has been compared with two current in-service systems in a helicopter underwater escape trainer.

METHOD

A total of 416 evacuations were conducted by 40 subjects in two experiments using the Survival Systems Limited's underwater escape trainer.

RESULTS

The UEE had a distinct 2-s advantage to escape; and, in the majority of cases, was preferred to a rotating lever or a straight push out system.

CONCLUSIONS

Further work should continue with UEE development for qualification in an operational helicopter.

Interleukin-8: A pathogenetic role in antineutrophil cytoplasmic autoantibody-associated glomerulonephritis

BACKGROUND

In neutrophil trafficking, the role of interleukin-8 (IL-8) is location dependent. Tissue IL-8 directs transmigration, whereas intravascular IL-8 frustrates this process. The bystander damage of glomerular endothelium by antineutrophil cytoplasmic autoantibody (ANCA)-activated neutrophils is believed to be an early event in the pathogenesis of ANCA-associated glomerulonephritis. We have studied the role of IL-8 in this process.

METHODS

Intraglomerular expression of IL-8 in patients with ANCA-associated glomerulonephritis was studied by in situ hybridization and immunohistochemistry and location of neutrophils by serial section immunohistochemistry. In vitro, we analyzed ANCA-stimulated neutrophil IL-8 production by enzyme-linked immunosorbent assay, and the IL-8 attributable effect of ANCA-stimulated neutrophil supernatant by chemotactic and transendothelial assays.

RESULTS

There was intraglomerular expression of IL-8 at segmental, crescentic, and parietal epithelial sites. IL-8 protein expression colocalized to intraglomerular neutrophils; many localized within glomerular capillary loops, suggesting failed trafficking to tissue IL-8. ANCAs differentially stimulated time- and dose-dependent neutrophil IL-8 production, and ANCA-stimulated neutrophil supernatant demonstrated potent IL-8-dependent chemotactic activity and inhibited transendothelial migration of normal human neutrophils toward an IL-8 gradient.

CONCLUSION

Despite heavy tissue expression of IL-8 in ANCA-associated GN, the production of IL-8 by ANCA-stimulated neutrophils within the intravascular compartment may frustrate neutrophil transmigration, encourage intravascular stasis, and contribute to bystander damage of glomerular endothelial cells.

The effect of wave motion on dry suit insulation and the responses to cold water immersion

METHODS

Six subjects who were each wearing a dry immersion suit system were immersed for 1 h in 16 degrees C water in a number of different wave conditions, ranging from still water to 70 cm in height. Physiological and physical parameters were measured in order to calculate the total thermal resistance of the suit system and its components.

RESULTS

None of the physiological parameters were affected significantly by the wave conditions, except for skin heat flux, which increased with wave height from 72.0 +/- 1.9 W x m(-2), at 0 cm of height, to 85.5 +/- 2.9 W x m(-2), at 70 cm of height. Wave heights up to 70 cm decreased the insulation (including boundary layer) of the dry suit system by 14%, and the only component of the suit affected by the wave motion was the insulation of the water boundary layer, which decreased by 75%. The body sites that were most affected by wave motion were the head and the trunk, with an average 45% decrement in suit system thermal resistance at those sites at wave heights of 0 to 70 cm. No significant effect was observed at sites on the distal limbs.

CONCLUSION

To simulate open ocean conditions in the laboratory, the standards must take the reduction of suit insulation into account.

Options for liferaft entry after helicopter ditching

METHOD

Dry and wet evacuations were conducted by 24 male and 19 female subjects from the Nutec Super Puma Simulator into two different types of aviation liferaft.

RESULTS

Dry evacuation on the windward side is the method of choice. The non-canopy raft is subjectively and objectively easier to enter both from the helicopter and the sea.

CONCLUSIONS

The non-canopy raft is the raft of choice, the canopy raft needs a redesign to ensure that it always inflates the correct way and both rafts need a redesign of the painter anchor point. Aircrew should have special training in open water after traditional pool training. A helicopter ditching survival compass has been developed for training all who fly over water for a living.

T lymphocyte responses to anti-neutrophil cytoplasmic autoantibody (ANCA) antigens are present in patients with ANCA-associated systemic vasculitis and persist during disease remission

ANCA with specificity for myeloperoxidase (MPO) and proteinase 3 (PR3) are present in patients with systemic vasculitis. The aim of this work was to determine whether such patients have T cell responses to these antigens and whether these responses are related to disease activity. Peripheral blood lymphocytes from 45 patients and 19 controls were cultured with ANCA antigens and proliferation measured. The antigens used were heat-inactivated (HI) MPO, HI PR3, native (non-HI) PR3, HI whole alpha-granules, and 25 overlapping peptides covering the entire PR3 sequence. Significant responses to both whole PR3 preparations were seen from patient and control groups, and to the alpha-granules from the patient group. Patients responded at all stages of disease: active, remitting, treated or untreated. Only two patients responded significantly to MPO. Responses were significantly higher with the patient group than the control group to all four whole ANCA antigens. Responses to those PR3 peptides containing epitopes known to be recognized by ANCA were detected from one patient. Thus, these studies demonstrate that T cells from vasculitis patients can proliferate to PR3 and occasionally to associated ANCA antigens. Further, responses may persist even after disease remission has been achieved.

High frequency ultrasound imaging using an active optical detector

Optical detection of ultrasound has numerous advantages over traditional piezoelectric methods. These systems offer noncontact inspection, rapid scanning capabilities, fine spatial sampling, and large bandwidths. In addition, difficulties associated with conventional ultrasound imaging systems such as cross-talk between elements, electrical connections, and electromechanical resonances are greatly reduced or even eliminated. Because of this, high frequency phased arrays for ultrasound detection can be emulated by accurately positioning and focusing optical beams on a suitable surface, which defines array elements. However, optical systems have lower sensitivity than their piezoelectric counterparts, limiting their widespread use in ultrasound imaging. Active optical detection offers a solution. An active ultrasound detector consisting of a neodymium-doped glass waveguide laser with an optical demodulation system, was built demonstrating enhanced sensitivity while preserving the benefits of traditional passive optical detection.

Helicopter door and window jettison mechanisms for underwater escape: ergonomic confusion!

There are 23 different door, hatch, and window release mechanisms identified in 35 types of helicopters that earn their living over water. There is no standardization of the mechanism within each cockpit or among helicopter types, nor is there any standardization of the location relative to the operation; whether the mechanism matches the task or in which direction the door/hatch/window is jettisoned. New regulations are needed by military and civilian authorities to address the ergonomic confusion.

Liferaft evacuation from a ditched helicopter: dry shod vs. swim away method

METHODS

There were 23 male and 21 female subjects who conducted a series of evacuations from the NUTEC Super Puma helicopter simulator into an RFD heliraft in the Bergen Fjord. The dry shod and swim-away methods were compared both on the windward and leeward side.

RESULTS

The dry shod method is the method of choice, although the swim-away method should be taught as an alternative in the event of imminent capsizing. Irrespective of method, evacuation wherever possible should be on the windward side.

CONCLUSIONS

Because it is critical for the aircrew to make a split-second decision concerning which method to use, they should have special training in open water after traditional pool training.

Cell adhesion molecule expression within human glomerular and kidney organ culture

A glomerular and kidney organ culture method was developed to study cytokine inducibility of adhesion molecules and MHC antigen expression. Glomerular cells showed constitutive expression of intercellular cell adhesion molecule-1 (ICAM-1) and MHC class I and II antigens, but not vascular cell adhesion molecule-1 (VCAM-1), E-selectin, or P-selectin. Expression of E-selectin on glomerular endothelial cells (ECs) was induced by interleukin-1 (IL-1), tumour necrosis factor (TNF), interferon-gamma (IFN-gamma) and granulocyte/ macrophage-colony stimulating factor (GM-CSF); this induction was inhibited by transforming growth factor beta (TGF beta) and by IL-4. P-selectin expression was never seen within glomeruli. VCAM-1 was constitutively expressed by Bowman's capsule and proximal tubules and was weakly induced on glomerular ECs by TNF and IL-4 in combination. Glomerular endothelial ICAM-1 expression was increased by IL-1, TNF, IFN-gamma, and GM-CSF, while TGF beta inhibited induction by TNF and IL-1. Expression of MHC class I and II antigens by glomerular ECs was constitutive; further upregulation of MHC class II by IFN-gamma was observed. These studies suggest that leukocyte-endothelial cell interactions that occur within the kidney follow broadly similar principles as are proposed to occur elsewhere in the body but, in addition, there are subtle differences that reflect local conditions.

IL-1 beta production by human polymorphonuclear leucocytes stimulated by anti-neutrophil cytoplasmic autoantibodies: relevance to systemic vasculitis

Neutrophils accumulate in the acute blood vessel lesions of patients with autoimmune systemic vasculitis. They have been shown previously to produce the cytokine IL-1 beta in response to stimulation with TNF. This study demonstrates that neutrophils can be stimulated by anti-neutrophil cytoplasmic antibodies (ANCA), which are present in patients with systemic vasculitis, to express mRNA and protein for IL-1 beta. Both human ANCA and MoAbs to a variety of autoantigens recognized by ANCA, including proteinase 3, myeloperoxidase, bactericidal/permeability increasing protein and elastase, are effective. This response can be inhibited by actinomycin and cycloheximide, suggesting a requirement for de novo protein synthesis. IL-1 beta production can be inhibited by pooled human intravenous immunoglobulins but not by FK506 or cyclosporin A. These data suggest that ANCA in patients with active vasculitis may stimulate neutrophils to produce cytokines. It is hypothesized that cytokine production from neutrophils that accumulate in significant numbers in vasculitic lesions contribute to and augment the local inflammatory response by the activation of vascular endothelial cells and infiltrating leucocytes.

Human vascular endothelial cells do not induce anergy in allogeneic CD4+ T cells unless costimulation is prevented

Human vascular endothelial cells expressing MHC class II molecules have previously been shown to stimulate the proliferation of allogeneic CD4+ human T lymphocytes. Here we show that allogeneic CD4+ T cells from individual A (TA) respond to class II+ endothelial cells from individual B (EB) by inducing interleukin (IL)-2 mRNA, detectable by semiquantitative polymerase chain reaction, within 12 hr. Responding T cells (TA) that are harvested after 12 hr, rested for 3 days, and then re-exposed to the same class II+ EB stimulators can again respond by proliferation that is equivalent in degree to that observed with third-party class II+ endothelial cells (EC) as stimulators and a little greater than that observed in the primary responses. Incorporation of antibodies to LFA-3, an endothelial costimulatory molecule for T cells, or to both IL-2 and IL-2 receptor (R) during the first-round stimulation prevented the subsequent second-round proliferation of TA to class II+ EB but not to class II+ EC. This nonresponsiveness induced by anti-LFA-3 or anti-IL-2/IL-2R could be overcome by the incorporation of cyclosporine during the first-round stimulation or by incorporation of IL-2 during the second-round stimulation. These observations suggest that class II+ endothelial cells within allografts will not induce anergy in host CD4+ T cells unless costimulation is blocked or the ability of CD4+ T cells to respond by proliferation is prevented; even then the response may be modified by prevailing cyclosporine or IL-2 levels.

Endothelial cells and renal epithelial cells do not express the Wegener's autoantigen, proteinase 3

Proteinase 3 (PR3) is the major antigen for autoantibodies (C-ANCA) against cytoplasmic components of neutrophils which are strongly associated with Wegener's granulomatosis (WG). Recent data that PR3 may be expressed by renal tubular epithelial cells and endothelial cells suggest potential for a direct pathogenic effect against these cells by C-ANCA or cytoxic T lymphocytes. Using a semi-quantitative polymerase chain reaction (PCR), ELISA and indirect immunofluorescence staining we studied endothelial and epithelial cell PR3 expression. By PCR, no PR3 expression was found in human umbilical vein endothelial cells (HUVEC) either untreated, or when treated with interferon-gamma (IFN-gamma) (200 U/ml, 6 h, 24 h), IL-1 (20 U/ml, 6 h), tumour necrosis factor-alpha, (TNF-alpha) (200 U/ml, 0, 1, 2, 4, 6 h) or IFN-gamma + TNF-alpha (6 h); iliac vein and artery endothelial cells did not express PR3 either. In contrast, PR3 was detected in HL60 cells and neutrophils by PCR, expression being confirmed by sequence analysis. Three PR3 MoAbs showed no binding to unstimulated or TNF-alpha-stimulated HUVEC either by ELISA or by indirect immunofluorescence staining. The epithelial cell line A549 expressed PR3 when assayed by PCR. However, three renal epithelial cell lines (two tubular and one glomerular) showed little or no PR3 expression by PCR or ELISA. These studies fail to demonstrate evidence for PR3 expression by endothelial cells, even when using the highly sensitive PCR assay. Whilst PR3 expression by A549 cells is intriguing, the relevance of this in the pathology of WG is doubtful considering the negligible expression by renal epithelial cell lines.

Human vascular endothelial cells process and present autoantigen to human T cell lines

The effectiveness of cultured human umbilical vein endothelial cells as accessory cells for T cell activation has been investigated using T cell clones and lines derived from patients with myasthenia gravis which were specific for different epitopes on the alpha subunit of the human acetylcholine receptor. The endothelial cells were induced with IFN-gamma to express HLA-DR and -DQ at high and low levels respectively. They could then efficiently present specific peptides of the alpha subunit to an HLA-DR- and an HLA-DQw5-restricted T cell line. They could also process epitopes for both T cell lines from the full-length recombinant alpha subunit (r1-437) of the human acetylcholine receptor, where the known epitopes are 80 amino acid residues apart. The endothelial presentation of r1-437, but not of the peptides, was sensitive to chloroquine inhibition. Presentation appeared slightly less efficient (by 1.5- to 3.0-fold) with endothelial cells than with presenting cells from peripheral blood. This may reflect differences in accessory signalling since mAb blocking studies suggested that ligands for CD28 provided important accessory signalling by peripheral blood presenting cells while LFA-3 was used by endothelial cells.

The ergonomics of jettisoning escape hatches in a ditched helicopter

The first formal investigation of the problem of location, operation and jettison of escape windows and hatches of helicopters following ditching has been conducted in a new simulator. There were 48 aircrew who attempted 298 escapes using a variety of 24 escape routes and 9 different types of escape hatches. Overall results, while superficially indicating that the task was easy, in fact revealed many unforeseen problems. Specifically, there was no standardization of hatches and levers, there were problems with location and operation of levers principally due to poor design, and an ergonomics study has not been conducted to investigate the problem. Underwater escape training with hatches in position must be mandatory for all who fly off-shore or over water for a living, and further research should be conducted to design a better standard hatch and jettison system.

Synergistic interactions of CD4+ and CD8+ T cell subsets with human vascular endothelial cells in primary proliferative allogeneic responses

The ability of subcultured human vascular endothelial cells (EC) to provide immune accessory functions for proliferative responses of highly purified allogeneic CD4+ and CD8+ T cells has been examined. CD4+ T cells proliferated in response to IFN-gamma-pretreated EC which expressed class II molecules, but not to untreated EC. CD8+ T cells proliferated to MHC class I molecules expressed on both untreated and IFN-gamma-treated EC. Combined populations of CD4+ and CD8+ T cells showed synergistic, rather than additive, responses to both untreated and IFN-gamma-treated EC. Furthermore, CD8+ T cells were able to induce MHC class II expression on endothelial cells and this induction could be inhibited by an anti-IFN-gamma mAb. The synergistic response obtained by co-culturing CD4+ and CD8+ T cells with vascular EC was completely inhibited by the same anti-IFN-gamma mAb. These studies suggest that CD4+ and CD8+ T cells recognise and proliferate to allogeneic MHC molecules expressed by EC. CD4+ and CD8+ responses are synergistic under the conditions tested and this synergism appears to be due to induction of MHC class II antigens on EC by IFN-gamma secreted from CD8+ T cells.

Assay of certain oral contraceptive formulations by gas chromatography-mass spectrometry-selected ion monitoring

The combined technique of gas chromatography--mass spectrometry--selected ion monitoring (GC-MS-SIM) has been employed for the nanogram level determination of ethinyloestradiol, mestranol, norgestrel and norethisterone in various oral contraceptive formulations. Steroids were assayed as their DMES-or methoxime DMES ether derivatives in the presence of ethisterone as the internal standard. The method is accurate, specific and suitable for single tablet assay.

Gas chromatographic assay of methyltestosterone in tablets

A simple gas chromatographic procedure has been developed for the determination of methyltestosterone in bulk powders and in tablets. Two new silyl ether derivatives of methyltestosterone have been prepared using dimethylethylsilylimidazole (DMESI) and dimethylisopropylsilylimidazole (DMiPSI). The method is accurate and selective for methyltestosterone within the concentration range 0.1-1.5 micrograms microliters-1.

Maximum acceptable inherent buoyancy limit for aircrew/passenger helicopter immersion suit systems

Helicopter crew and passengers flying over cold water wear immersion suits to provide hypothermic protection in case of ditching in cold water. The suits and linings have trapped air in the material to provide the necessary insulation and are thus very buoyant. By paradox, this buoyancy may be too much for a survivor to overcome in escaping from the cabin of a rapidly sinking inverted helicopter. The Canadian General Standard Board requested that research be conducted to investigate what should be the maximum inherent buoyancy in an immersion suit that would not inhibit escape, yet would provide adequate thermal insulation. This experiment reports on 12 subjects who safely escaped with 146N (33 lbf) of added buoyancy from a helicopter underwater escape trainer. It discusses the logic for and recommendation that the inherent buoyancy in a helicopter crew/passenger immersion suit system should not exceed this figure.

Loss of cabin pressure in Canadian Forces transport aircraft, 1963-1984

A review of all transport aircraft accidents and incidents in the Canadian Forces over the last 22 years (1963-1984) has been carried out. There have been 47 cases of serious loss of cabin pressurization. Altitudes varied from 2133 to 11277 m (7000 to 37,000 ft). The CC 130 Hercules appears to be the most vulnerable (62%). The most common cause was mechanical in origin (70%). There were two definite cases of hypoxia, and oxygen masks were deliberately deployed in nine cases. No deaths or permanent injuries occurred. Loss of pressurization is an extremely low, but definite risk to the pilot and passengers, thus aeromedical training with practical demonstrations in the hypobaric chamber for aircrew and flight attendants should continue.

Ship/rig personnel abandonment and helicopter crew/passenger immersion suits: the requirements in the North Atlantic

Protection from hypothermia and drowning are the primary requirements for an immersion suit system during ship, rig, or helicopter abandonment in the North Atlantic. In order to achieve this, the suit must be dry and comfortable. The problems involved in manufacturing such a suit are discussed and the fact is that there is still not a suit in existence that fulfills all the criteria.

Loss of cabin pressure in Canadian Forces ejection seat aircraft, 1962-1982

A review of all aircraft accidents and incidents in the Canadian Forces over the last 20 years (1962-1982) has been carried out. There have been 47 cases of serious loss of cabin pressurization in ejection seat equipped aircraft. Altitudes varied from 15,000 to 54,000 ft (4,572-16,459 m). No one aircraft appears to be more vulnerable. The most common cause was problems with the canopy seal (25%). There were three cases of hypoxia and two cases of decompression sickness. No deaths or permanent injuries occurred. Loss of pressurization is an extremely low, but definite risk to the pilot and aeromedical training with practical demonstration in the hypobaric chamber should continue.

Head and neck injuries in Canadian Forces ejections

This paper reviews the head and neck injuries experienced by Canadian Forces Aircrew who ejected while wearing the DH 41-2 helmet during the period from 1 Jan. 1972 through 31 July 1982. Pre and post-ejection factors, including a review of helmet performance, are presented.

Water survival: 20 years Canadian Forces aircrew experience

A 20 year review of Canadian Forces (CF) aircrew ejection/ditching, survival/rescue times and injury patterns in salt and fresh water is presented. Of the 595 A, B, and C category accidents which have been reviewed (1962-1982), 37 were water-entry. Of the 116 crew which were involved, 38 died (4 in fresh water). The Sea King helicopter is most at risk from sea water immersion, and the single-engine Otter has been the most vulnerable to fresh water immersion. A water immersion can be expected approximately once every 170,000 h of total flying time. In 92% of cases, the crew had less than 1 min warning that immersion was imminent and in 78% had less than 15 s to make a practical response. There were two clinical cases of hypothermia. In the absence of injuries, aircrew trained in water survival, qualified on the Dilbert Dunker, and who are strong swimmers or sports divers, have a better chance to survival. Time to rescue in all cases was under 3 h, and in 16 out of 24 cases crew members were rescued in under 15 min.

Selective reactions in the analytical characterisation of steroids by gas chromatography-mass spectrometry

The analytical characterization, by GC-MS, of individual compounds in mixtures of steroids, such as occur frequently in biological extracts, is difficult because of the close similarities in structure and properties of many components. The improved separating power of capillary (open-tubular) columns alleviates the problem, but does not solve it fully: for example, the coincidence of retention times of two different compounds may still be virtually complete. Comparative analyses on two distinctively different phases afford one valuable application of selectivity, but may not always be feasible when costly columns are required. Comparative analyses of the sample, before and after effecting its modification by well-defined reactions, are inexpensive and are particularly when selective transformations are used. The use of the microbial enzyme cholesterol oxidase as a selective oxidant for 3 beta-hydroxysteroids (chiefly limited to 4-ene, 5-ene and 5 alpha-types) is illustrated for a model mixture of androstanols related to the boar pheromone (5 alpha, 16-androsten-3 alpha-ol). Retention regularities and changes in mass spectra enhance the reliability of identifications. An exploratory application of cholesterol oxidase in the analysis of minor "polar" sterols in human serum is reported. Most of the known minor sterols are good substrates for the enzyme, and their transformation products yield distinctive GC-MS data, as exemplified for the 7 alpha- and 7 beta-hydroxycholesterols. Another convenient and versatile selective reagent is methaneboronic acid, which yields cyclic esters of suitably constituted diols. These derivatives have shorter retention times (on "non-polar" phases) than the di-TMS ethers, chiefly by virtue of their much lower molecular weights. The mass spectra of cyclic boronates generally show clear molecular ions, also fragmentations that complement the information obtainable from the di-TMS ethers. These features are illustrated for a group of diols and triols of the 5 alpha-pregnane series.

Selective reactions in the analysis and characterization of steroids by gas chromatography-mass spectrometry

Gas chromatography-mass spectrometry (GC-MS) is a technique especially suitable for the analysis and characterization of steroids, and its power has been extensively demonstrated. The efficacy of GC-MS is limited, nevertheless, by the fact that steroid mixtures - whether of natural origin only, or augmented by synthetic analogs - often contain similar components that are poorly distinquished. The fortuitous overlap of gas chromatographic peaks from disparate compounds also impairs the definition of retention data. Controlled modification of the sample by means of selective reactions is therefore a valuable adjunct to the application of GC-MS. Two examples are discussed: (a) the enzyme cholesterol oxidase, isolated from various microorganisms, catalyzes the oxidation of many 3 beta-hydroxy-5-enes (with concomitant isomerization) to 4-en-3-ones; 3 beta-hydroxy-5 alpha-steroids are also oxidized to the corresponding 3-ones, but other steroids (3 alpha-hydroxy- or 5 beta-isomers, etc.) are unaffected. The mild conditions required (pH 7, 30 C) are advantageous for the analysis of sensitive steroids, and the retention index increments, as well as the mass spectra of the ketones, are characteristic. The enzyme accepts as substrates a wide range of 3 beta-hydroxysteroids, tolerating oxygenation in ring B and even catalyzing the oxidation of 2-oxacholesterol to the expected lactone; and (b) Steroids possessing 1,2-diol or 1,3-diol groupings include estriols, 2-hydroxyestrone, 20,22-dihydroxycholesterols, ecdysones, brassinolide and many corticosteroids. The selective formation of cyclic derivatives can provide several analytically useful features, such as convenient retention times, moderate mass increments (24 amu for a methaneboronate), distinctive mass spectra and usually abundant molecular ions. These are exemplified for 5-pregnene-3 beta, 20,21-triols and for 20,22-dihydroxycholesterol as well as its enzymic oxidation product.

Development of a procedure for the assay of an experimental steroid drug in dog plasma

Studies of the estimation of 16alpha-cyano-3beta-cyclopentyloxypregn-5-en-20-one (an experimental drug) in dog plasma are described. Extraction using a salt/solvent pair (ammonium carbonate/ethyl acetate) is followed by a rapid chromatographic procedure employing Lipidex 5000, which affords a substantially purified fraction. After preparation of the t-butyldimethylsilyloxime, quantification of the drug is performed by selected ion monitoring. The [2H9]cyclopentyloxyl analogue is used as an internal standard. In a preliminary experiment, the advantages (in terms of both sensitivity and selectivity) of the use of an open tubular GLC column are demonstrated.

Application of ion-exchange and lipophilic-gel chromatography to the purification and group fractionation of steroidal spirolactones, isolated from biological fluids

Chromatography of steroidal spirolactones on DEAE-Sephadex A-25 under selected pH conditions allowed efficient separation of these compounds from other steroids and many of the endogenous components of human urine. The spirolactones were recovered in high yield, mostly over 90%. Lipophilic-gel chromatography provided a useful method for group fractionation of mixtures of these spirolactones with high recoveries (generally over 90%), unaffected by the presence of endogenous material from normal human urine.

Oxidation of 3beta-hydroxyandrostenes by the 3beta-hydroxy-steroid oxidase (cholesterol oxidase) from Brevibacterium sterolicum prior to their analysis by gas-liquid chromatography-mass spectrometry

The 3beta-hydroxysteroid oxidase from Brevibacterium sterolicum has been applied to the oxidation of a number of 3beta-hydroxyandrostenes, including polar steroids containing up to three other hydroxylic groups. The substrates, products, and derivatives thereof have been examined by gas-liquid chromatography. Retention index increments for these conversions, and for parallel transformations of other steroids, show considerable regularities, and together with mass spectrometric data afford characteristic structural information.

Gas-liquid chromatography-mass spectrometry of phospholipid mixtures after enzymic hydrolysis

Gas-liquid chromatography-mass spectrometry (GLC-MS), employing an open-tubular Silanox-type glass column, has been applied to the products of phospholipase C hydrolysis of natural and synthetic phospholipid mixtures. The materials studied were egg lysolecithin, synthetic L-alpha-l-stearoyl-2-oleoyl lecithin, bovine brain sphingomyelin, and phospholipids derived from human arterial tissue. l-Monoglycerides and ceramides were analysed as methaneboronates, and 1,2-diglycerides as trimethylsilyl ethers. The results indicate the potential value of open-tubular GLC-MS in a rapid procedure for the concurrent analysis of the major classes or polar lipids after enzymic dephosphorylation.

Gas-liquid chromatography-mass spectrometry of thromboxane B2 and its detection in semen and human aorta by selected ion monitoring

The gas-liquid chromatographic and mass spectrometric properties of some derivatives of thromboxane B2 methyl ester have been examined. Mass spectra were usually more informative at lower electron energies. The O-methyl- and O-n-propyloxime tri-trimethylsilyl ethers, and the tri-tert.-butyldimethylsilyl ether were used for selected ion monitoring (SIM). Thromboxane B2 was detected by SIM in bovine semen and in human aorta.

The substrate specificity and stereochemistry, reversibility and inhibition of the 3-oxo steroid delta 4-delta 5-isomerase component of cholesterol oxidase

1. 5-Cholesten-3-one was shown to be an intermediate in the conversion of cholesterol into 4-cholesten-3-one by Nocardia cholesterol oxidase. 2. The absence of a C-17 side chain from 5-androstene-3,17-dione slightly increased the Vmax. of the isomerase activity relative to 5-cholesten-3-one (1.7-fold), but greatly increased the Km. 3. Incubations of [4alpha-2H]-and [4beta-2H]-cholesterol with cholesterol oxidase showed that the 4beta-hydrogen atom can be transferred to the 6beta-position. However, incubations of cholesterol, 5-cholesten-3-one and 4-cholesten-3-one with the enzyme in 2H2O led to some incorporation of 2H into the 4-cholesten-3-one products, mostly at position 6beta. 4. Both the isomerase and the oxidase activities of cholesterol oxidase were inhibited by 5,10-seco-19-nor-5-cholestyne-3,10-dione.

Gas chromatography chemical ionization mass spectrometry of prostaglandin Falpha cyclic boronate derivatives

The electron impact mass spectra of prostaglandins F 1alpha, F 2alpha and F 3alpha methyl ester cyclic 9,11-methane-, n-butane-, cyclohexane- and benzeneboronate 15-trimethylsilyl ethers show base peaks corresponding to [M-(C-16-C-20)]+, i.e. [M-71]+ for prostaglandins F 1alpha and F 2alpha but [M-69]+ for prostaglandin F 3alpha yielding identical ions in the latter two cases. Derivatives of prostaglandin F 2alpha and F 3alpha are difficult to separate by gas chromatography, so that the use of this ion type for single ion monitoring of either prostaglandin (as has been reported) is ambiguous. The chemical ionization mass spectra of these cyclic boronates, however, show distinctive base peaks for prostaglandins F 1alpha, F 2alpha and F 3alpha at m/e 317,315 and 313 respectively, corresponding to [M-RBO2H2-TMSO]+. Fragmentation patterns have been investigated by the use of [3,3,4,4-2H4]prostaglandin F 2alpha and by the formation of [2H9]trimethylsilyl ethers and a [2H3]methyl ester. Cleavage of the C-15-C-16 bond is of minor importance under chemical ionization conditions. The possible value of the [M-RBO2H2-TMSO]+ ions for single ion monitoring is explored: specificity is aided by the formation of the same ions from a series of boronates of characteristic retention indices.

Characterization of diastereomeric and enantiomeric ephedrines by gas chromatography combined with electron impact mass spectrometry and isobutane chemical ionization mass spectrometry

The diastereomeric hydroxyamines, ephedrine and psi-ephedrine, were well differentiated by gas chromatography of their N-acetyl O-trimethylsilyl derivatives. For the analytical separation of enantiomers, conversion into N-(R)-alpha-phenylbutyryl O-trimethylsilyl derivatives was effective in the cases of ephedrine, psi-ephedrine and nor-psi-ephedrine (but not that of nor-ephedrine, on the two stationary phases used). Electron impact mass spectra showed structurally diagnostic fragmentations, but the two diastereomeric amides from each pair of enantiomers yielded generally similar spectra. Molecular ions were of low abundance, but under chemical ionization conditions (isobutane) abundant protonated molecular ions were produced.