Birth outcomes following treatment for precancerous changes to the cervix: a population-based record linkage study.

OBJECTIVE: To examine whether treatments for precancerous changes to the cervix are associated with adverse birth outcomes in subsequent pregnancies. DESIGN: Population-based retrospective cohort study using electronic linkage of data from the Welsh cervical screening programme and a national routine child health database. SETTING: Wales. POPULATION: A total of 174,325 women aged 20-39 years who received cervical screening between April 2001 and March 2004. METHODS: Logistic regression was used to compare the odds of each birth outcome between women who had negative cervical smears and women who received either colposcopy ± punch biopsy only or colposcopy and excisional or ablative treatments, adjusted for confounding factors (e.g. age, social deprivation and smoking). MAIN OUTCOME MEASURES: Preterm birth (before 37, 32 and 28 weeks of gestation), and low birthweight (<2500 g). RESULTS: Compared with women who had negative cervical smears, the odds ratio for preterm birth (<37 weeks) was significantly increased in women who had colposcopy only (adjusted odds ratio 1.54, 95% CI 1.32-1.80) and single excisional treatment (adjusted odds ratio 1.77, 95% CI 1.47-2.13). Similar results were observed for preterm birth at <32 weeks of gestation. There was no increased risk of preterm birth or low birthweight for women who had treatment compared with women who had colposcopy only. CONCLUSION: Women who were referred for colposcopy had an increased risk of preterm births regardless of whether or not they received treatment to the cervix. This increased risk could be the result of common risk factors for abnormal smears and preterm birth.

Clinical feasibility study of protrach dualcare a new speaking valve with heat and moisture exchanger for tracheotomized patients.

Objective: The aim of this study was to evaluate the clinical feasibility of the ProTrach DualCare (Atos Medical, Hörby, Sweden), a device combining a hands-free speaking valve and a Heat and Moisture Exchanger (HME) for tracheotomized patients. Study Design: A non-randomized, prospective single center feasibility study. Methods: Sixteen adult tracheotomized patients were included. Participants were asked to test the DualCare for two weeks while continuing their normal activities. After these two weeks, participants could choose whether or not to take part in the long-term evaluation. The EuroQOL-5D, Borg scale and questionnaires on speaking, pulmonary function and patient preference were used. During the long-term evaluation, a minor redesign was implemented and all participants were asked to test the new device again for one week, with a potential long-term evaluation. Eleven decided to participate. Results: The device was well-tolerated. Speaking noise was reduced (p = 0.020) and speech was considered to sound more natural compared to previously used devices according to the users (p = 0.020). Overall 11 participants preferred the DualCare to their standard device. No serious adverse events were reported. Conclusion: Overall, 11 of 16 participants preferred the DualCare to their standard speaking valve or HME. Users of the DualCare were able to use hands free speech with the benefits of an HME and the device was considered clinically feasible and has the potential to improve quality of life of tracheotomized patients. Level of Evidence: 2b.

The intelligibility of tracheoesophageal speech, with an emphasis on the voiced-voiceless distinction.

Total laryngectomy has far-reaching effects on vocal tract anatomy and physiology. The preferred method for restoring postlaryngectomy oral communication is prosthetic tracheoesophageal (TE) speech, which like laryngeal speech is pulmonary driven. TE speech quality is better than esophageal or electrolarynx speech quality, but still very deviant from laryngeal speech. For a better understanding of neoglottis physiology and for improving rehabilitation results, study of TE speech intelligibility remains important. Methods used were perceptual evaluation, acoustic analyses, and digital high-speed imaging. First results show large variations between speakers and especially difficulty in producing voiced-voiceless distinction. This paper discusses first results of our experiment.

Compliance, quality of life and quantitative voice quality aspects of hands-free speech.

CONCLUSIONS: With the use of a new automatic stoma valve (ASV) it appears possible to rehabilitate patients who have previously been unsuccessful in acquiring hands-free speech. As well as making daily ASV use possible for an additional group of patients, this new device was also appreciated by many patients as an additional rehabilitation tool for specific occasions. Despite statistically significant improvements in aspects of voice and breathing using this novel ASV, improvement of peristomal adhesion is probably the main factor needed to further increase success rates. Nevertheless, our results show that it makes sense to keep trying to achieve hands-free speech, even if previous attempts have failed. OBJECTIVE: To make a long-term (6 months) assessment of compliance and aspects of voice, breathing and quality of life using a new ASV: the Provox FreeHands heat and moisture exchanger (HME). MATERIAL AND METHODS: This was a prospective clinical multicentre trial in 79 laryngectomized patients (8 regular ASV users, 58 previously unsuccessful users and 13 new users). Data were collected at baseline and after 1 and 6 months by means of European Organization for Research and Treatment of Cancer Quality of Life questionnaires and specific structured questionnaires concerning compliance, skin adhesion, voicing and pulmonary aspects. An objective assessment of voice parameters (maximum phonation time, maximum phonation time while counting, dynamic loudness range and number of pauses in a standard read-aloud text) was made for comparison of different stoma occlusion methods (digital occlusion via an HME and two different ASVs). A subjective assessment of overall voice quality was made. RESULTS: After 6 months, 19% of patients used the new ASV on a daily basis (mean 5 h/day), while 57% used it on an irregular basis as an additional rehabilitation tool for special occasions. Two-thirds of the study group indicated that they would continue to use the new ASV after the study period. With respect to the objective parameters, statistically significantly better maximum phonation times and dynamic loudness ranges were observed with the new ASV compared to the Blom-Singer ASV. However, the best results for all the objective parameters were obtained with digital occlusion via the Provox HME.

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.

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.

Sterols of scallop. Part II. Structure of unknown sterols by combination gas-liquid chromatography and mass spectrometry.

Four sterols, isolated from the scallop Pacopecten magellanicus have been identified as 24-nor-5alpha-cholest-22-en-3beta-ol; 24-norcholest-5-en-3beta-ol; 5alpha-cholest-22-en-3beta-ol; and (E) -24-propylidenecholest-5-en-3beta-ol. These bring to seventeen the total number of sterols identified in this marine mollusc. A fifth newly detected sterol, closely similar in its mass spectrometric properties is 22-cis and trans-cholesta-5, 22-dien-3beta-ol, was clearly distinguished from these by its shorter retention time by GLC.

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.

Characterization of sterols by gas chromatography-mass spectrometry of the trimethylsilyl ethers.

The utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols has been explored. Methylene unit (MU) values and principal mass spectrometric data are presented for trimethylsilyl ethers of 28 sterols, including the major natural sterols. The diagnostic value of the fragmentation of trimethylsilyl ethers of Delta(5)-3 beta-hydroxysteroids has been confirmed. Characteristic fragmentations of Delta(4)-3 beta-trimethylsilyloxysteroids, and of Delta(5,7)-3 beta-trimethylsilyloxysteroids were also found. Location of side-chain hydroxyl groups is facilitated by the alpha-cleavages typical of the trimethylsilyl ethers. Fragmentations of saturated sterols, and of Delta(7), Delta(8(9)) and Delta((14)) stenols, are less influenced by trimethylsilyl ether formation, but the derivatives still afford satisfactory mass spectra. The combination of gas chromatographic and mass spectrometric information allows positive identification of any of the sterols examined, whereas application of either technique alone may give inconclusive results.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.