Aspartyl proteases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep

A novel pepsin-like aspartyl protease was identified as a component of Haemonchus galactose-containing glycoprotein (H-gal-GP), which is an integral membrane glycoprotein complex located on the intestinal cells of Haemonchus contortus, and a highly protective antigen for sheep. This molecule, designated HcPEP2, showed 50% sequence identity with a previously described aspartyl protease from H-gal-GP known as HcPEP1. Fractions of H-gal-GP, either containing both HcPEP1 and 2 or other lower molecular weight components of the complex, were evaluated as protective antigens in immunization - challenge trials in sheep. When separated from the rest of the complex by gel filtration in 8 m urea, the HcPEP1 and 2 fraction significantly reduced H. contortus egg counts by 48% and worm numbers by 36%, but the lower molecular weight components were not significantly protective. However, the HcPEP1 and 2 fraction did not protect if electro-eluted from SDS-dissociated H-gal-GP, nor did bacterially expressed recombinant HcPEP1, suggesting that conformational epitopes are important for inducing immunity.

Attempts to immunize sheep against the scab mite, Psoroptes ovis

Adult Psoroptes ovis were successively extracted in saline, 1% Tween, 1% Triton and 8 m urea +0.1% CHAPS. The Triton extract was separated into fractions which did or did not bind to ConA lectin. Using QuilA as adjuvant, both Triton fractions and the saline, Tween and urea extracts were tested separately as candidate protective antigens against a P. ovis challenge infestation in sheep. All induced circulating antibody responses, but the saline and Tween extracts also stimulated significant protective effects in those sheep which developed active disease. Compared to control sheep injected with adjuvant only, these immunized animals had more than two and seven-fold reductions in mean lesion areas and mite numbers, respectively.

An ergonomic study of the optimum operating table height for laparoscopic surgery

BACKGROUND

Laparoscopic surgery requires the use of longer instruments than open surgery, thus changing the relation between the height of the surgeon's hands and the desirable height of the operating room table. The optimum height of the operating room table for laparoscopic surgery is investigated in this study.

METHODS

Twenty-one surgeons performed a two-handed, one-fourth circle cutting task using a laparoscopic video system and laparoscopic instruments positioned at five instrument handle heights relative to subjects' elbow height (-20, -10, 0, +10, and +20 cm) by adjusting the height of the trainer box. Subjects rated the difficulty and discomfort experienced during each task on a visual analog scale. Skin conductance (SC) was measured in Micromhos via paired surface electrodes placed near the ulnar edge of the palm of the right (cutting) hand. The mean electromyographic (EMG) signal from the right deltoid and trapezius muscles was measured. Arm orientation was measured in three dimensions using a magnetometer/accelerometer. Signals were acquired using analog circuitry and digitally sampled using a National Instruments DAQCard 700 connected to a Macintosh PowerBook 5300c running LabVIEW software. Statistical analysis was carried out by analysis of variance and post hoc testing.

RESULTS

Statistically significant changes were found in the subjective rating of discomfort (p <0.002), deltoid EMG (p <0.0006), trapezius EMG (p <0.0001), and arm elevation (p <0.0001) between instrument handle heights. SC values and task times did not change significantly. Discomfort and difficulty ratings were lowest when instrument handles were positioned at elbow height. EMG values and arm elevation all decreased with lower instrument height.

CONCLUSION

This study suggests that the optimum table height for laparoscopic surgery should position the laparoscopic instrument handles close to surgeons' elbow level to minimize discomfort and upper arm and shoulder muscle work. This corresponds to an approximate table height of 64 to 77 cm above floor level. A redesign of current operating room tables may be required to meet these ergonomic guidelines.

Development of a protocol for monitoring status and trends in forest soil carbon at a national level

The national Forest Health Monitoring (FHM) program requires protocols for monitoring soil carbon contents. In a pilot study, 30 FHM plots loblolly shortleaf (Pinus taeda L./Pinus echinata Mill.) pine forests across Georgia were sampled by horizon and by depth increments. For total soil carbon, approximately 40% of the variance was between plots, 40% between subplots and 20% within subplots. Results by depth differed from those obtained by horizon primarily due to the rapid changes in carbon content from the top to the bottom of the A horizon. Published soil survey information overestimated bulk densities for these forest sites. The measurement of forest floor depths as a substitute to sampling did not provide reliable estimates of forest floor carbon. Precision of replicate samples was approximately 10-30% for field duplicates and 5-10% for laboratory duplicates. Based on national indicator evaluation criteria, sampling by depth using bulk density core samplers has been recommended for national implementation. Additional procedures are needed when sampling organic soils or soils with a high percentage of large rock fragments.

An ergonomic evaluation of surgeons' axial skeletal and upper extremity movements during laparoscopic and open surgery

BACKGROUND

Many surgeons have complained of fatigue and musculoskeletal pain after laparoscopic surgery. We evaluated differences in surgeons' axial skeletal and upper extremity movements during laparoscopic and open operations.

METHODS

Five surgeons were videotaped performing 16 operations (8 laparoscopic and 8 open) to record their neck, trunk, shoulder, elbow, and wrist movements during the first hour of surgery. We also compared postprocedural complaints of pain, stiffness, or numbness between the two groups.

RESULTS

Compared with surgeons performing open surgery, surgeons performing laparoscopic surgery exhibited less lateral neck flexion; less trunk flexion; more internal rotation of the shoulders; more elbow flexion; more wrist supination and wrist ulnar and radial deviation. There was a trend of more shoulder stiffness after laparoscopic operations than after open operations.

CONCLUSIONS

Laparoscopic surgery involves a more static posture of the neck and trunk, but more frequent awkward movements of the upper extremities than open surgery. Ergonomic changes in the operating room environment and instrument design could ease the physical stress imposed on surgeons during laparoscopic operations.

Performing laparoscopic surgery is significantly more stressful for the surgeon than open surgery

BACKGROUND

The awkward visual and physical interface of video-endoscopic surgery (VES) has been shown to increase the physical workload of the surgeon, yet there is a lack of objective information on the mental effort and stress demanded by VES techniques. This study addresses the hypothesis that VES is more stressful than open surgery using an ergonomic analysis of surgical tasks in a laboratory setting.

METHODS

A portable ergonomic work station was developed using a software Virtual Instrument (VI) interfaced with electronic hardware to compare the mental workload of 28 surgeons. The task was knot tying. The independent variable was work condition: rest, open technique, or VES technique. Dependent variables were tonic skin conductance level (SCL), electrooculogram (EOG), and subjective reports of concentration (CON) and stress (STR). Statistical analysis used nonparametric methods.

RESULTS

Subjects tied fewer knots using the VES technique (p < 0.05). The SCL increased progressively from rest to the open task to the VES task (p < 0.05), correlating with the subjects' reported increase in mental stress level (p < 0.05). Eye blinks decreased from rest to the open task (p < 0.05), consistent with the subjects' reported increase in level of mental concentration. From the open to the VES task, eye blinks increased (p < 0.05), as would be expected given the greater demands of the VES task. Experienced subjects demonstrated less variability in SCL levels across tasks.

CONCLUSIONS

VES technique requires greater concentration and places greater mental stress on surgeons than to open surgery. More experience with VES may decrease this effect. Studies are needed to improve the human-technology interface the stress.

Vaccination against gastrointestinal nematode parasites of ruminants using gut-expressed antigens

To date, proteins isolated from the surface of the gut of gastrointestinal nematodes, particularly Haemonchus contortus, have generally proved to be useful protective antigens and several are being progressed towards recombinant protein-based vaccines. This paper describes the properties of some of the most promising antigens and summarises their performance in laboratory and field based trials. The antigens described include contortin, H11, H-gal-GP, GPI and cysteine proteinases. In addition, the discussion addresses the utility of selected antigens to protect against co-infecting nematode species such as Teladorsagia circumcincta and against related nematode infections such as Ostertagia ostertagi in cattle.

The effect of laparoscopic instrument working angle on surgeons' upper extremity workload

BACKGROUND

Laparoscopic surgery may be kinder to the patient, but it is more demanding on the surgeon. Fixed trocar positions often require the surgeon to work with instruments at awkward angles to their body. We studied the effect of horizontal and vertical laparoscopic instrument working angle on the surgeon's thumb, forearm, and shoulder muscle work.

METHODS

Electronyographic (EMG) signals were collected from the thenar compartment (TH), flexor digitorum superficialis (FDS), and deltoid (DEL) muscles of the dominant arm of eighth surgeons while they were closing a standard pistol-grip disposable laparoscopic grasper against a fixed resistance of 3 N. With the aid of a special testing bench, the instruments' position was randomly changed among 15 degrees, 45 degrees, and 75 degrees of horizontal angulation relative to the surgeons' sagital plane, and 15 degrees, 45 degrees, and 75 degrees degrees of vertical angulation relative to a horizontal plane. EMG signals were rectified and smoothed using analogue circuitry and digitally sampled at l0 Hz using a National Instruments DAQCard-700 connected to a Macintosh PowerBook 5300c running LabVIEW software. Statistical analysis was carried out by analysis of variance (ANOVA).

RESULTS

The effects of vertical and horizontal working angles on the muscle effort were as follows: TH (horizontal, N.S.; vertical, N.S.), FDS (horizontal, p 45 degrees to the surgeon's sagital plane significantly increases the workload of the flexor digitorium superficialis and deltoid muscles. The deltoid muscle is also adversely affected by vertical angulation of the instrument. The instrument working angle has no effect on the thenar muscles. Whenever possible, laparoscopic surgeons should strive to place their instruments and trocars so as to minimize extreme horizontal or vertical displacement of their hands away from a resting position of comfort.

Preliminary observations on the potential of gut membrane proteins of Haemonchus contortus as candidate vaccine antigens in sheep on naturally infected pasture

In a trial lasting 11 months in South Africa, faecal egg counts and haematocrits of sheep vaccinated with gut membrane proteins of adult Haemonchus contortus were compared with unvaccinated controls grazing pasture contaminated with the parasite. Vaccination reduced egg output by >82% on average during one 4 month period of the trial and simultaneously significantly reduced the degree of anaemia and deaths due to haemonchosis. Although vaccine immunity was not sufficiently long lasting to prevent a surge in egg output which occurred after the onset of a period of irrigation, re-vaccinating the sheep at this point cleared their newly acquired infection and rapidly restored protection to approximately the level observed beforehand. It was clear that a vaccine based on parasite gut membrane proteins could offer substantial benefits in the control of natural haemonchosis.

Cross-protection studies with gut membrane glycoprotein antigens from Haemonchus contortus and Teladorsagia circumcincta

Gel profiles of the peanut and ConA lectin binding integral membrane glycoproteins of Teladorsagia circumcincta and Haemonchus contortus were compared and found to be considerably different. However, some of the Teladorsagia polypeptides were recognized by antisera specific for Haemonchus amino-, metallo- or aspartyl peptidases, enzymes which are known to be protective antigens for that parasite. As expected, an experimental vaccine containing these Haemonchus proteases was extremely effective against homologous challenge, reducing egg and worm counts by more than 99% and 92%, respectively, but it did not provide any useful cross-protection against either T. circumcincta, Trichostrongylus axei or Cooperiaoncophora. A reciprocal experiment, where sheep were immunized with the equivalent glycoproteins from T. circumcincta, showed that, while they were not protected against homologous challenge, there was some cross-protection against Haemonchus as measured by a significant reduction in worm egg output.

Cloning and expression of cystatin, a potent cysteine protease inhibitor from the gut of Haemonchus contortus

A cDNA encoding a cysteine protease inhibitor (cystatin) was identified by immunoscreening a Haemonchus contortus cDNA library with antisera from lambs vaccinated with a protective membrane protein complex (H-gal-GP) derived from the gut of the parasite. The cDNA sequence, designated Cys-1, showed significant levels of similarity with cystatins from several species of nematode as well as with human cystatin. Recombinant H. contortus cystatin was expressed in Escherichia coli in a soluble and functionally active form, which proved to be a potent inhibitor of both mammalian cathepsin B and native H. contortus cysteine proteases. Immunolocalization studies using antisera raised against recombinant H. contortus cystatin showed that the inhibitor was predominantly expressed in the cytoplasm of intestinal cells. To determine whether H. contortus had any protective capacity against infection, lambs were vaccinated with the recombinant molecule and subsequently given a single challenge infection. Although vaccination did not confer any protection against infection with H. contortus, as judged by faecal egg output or worm counts, cystatin will be a valuable tool in the analysis of the function of the cysteine proteases which are the subject of on-going study as potential vaccine components.

Approaches to vaccines for Psoroptes ovis (sheep scab)

A brief outline of the history of sheep scab in the UK is presented together with the current chemical methods used for its control and problems associated with these. Possible alternative approaches to control are discussed, as are selected aspects of the physiology of Psoroptes ovis and the pathogenesis of the scab lesion from the perspective of control through immunisation. Evidence is provided that immunity to the disease can indeed be acquired, both naturally after a previous infection and following inoculation of mite proteins in adjuvant. These results support the view that control by vaccination may be possible, although little is known to date about the antigens involved or the mechanism of protection.

Dynamic ventilatory response to acute isocapnic hypoxia in septuagenarians

This study compared the ventilatory response to 20 min of acute isocapnic hypoxia (end-tidal P(O(2)), 50 mmHg) using the technique of dynamic end-tidal forcing in young (Y) and old (O) men. Two groups of non-smoking male subjects (mean +/- s.d. age: Y, 29.8 +/- 6.9 years; O, 73.4 +/- 2.8 years) with similar body size, normal age-predicted spirometry, and normal moderate levels of physical activity were studied. Compared with baseline ventilation in euoxia (10.79 +/- 1.99 and 11.88 +/- 0.91 l min-1) both groups responded to the abrupt onset of isocapnic hypoxia with peak ventilatory responses of 22.58 +/- 2.60 and 24.56 +/- 2.54 l min-1 for Y and O, respectively (not significant, n.s.). Both groups demonstrated a significant increment in neuromuscular drive (i.e. tidal volume (V(T))/inspiratory time (T(I)); 0.46 +/- 0.06 to 0.91 +/- 0.15 and 0.48 +/- 0.06 to 0.91 +/- 0.12 l s-1 for Y and O, respectively) with a small (but also significant) change in central timing (T(I)/total ventilation time (T(tot)); 0.38 +/- 0.02 to 0.41 +/- 0.02 and 0.42 +/- 0.02 to 0.45 +/- 0.02 for Y and O, respectively). Oxygen sensitivity was assessed using Weil's equation, and gave a hyperbolic factor (A) of 282 +/- 75 and 317 +/- 72, and using the linear equation: change in expiratory minute volume (DeltaV.(E))/change in arterial O(2) saturation (DeltaS(a,O(2))) which gave -1.17 +/- 0.57 and -1.17 +/- 0.42 l min-1 %-1 (n.s.) for Y and O, respectively. After 20 min of sustained isocapnic hypoxia, ventilation declined to 14.29 +/- 1.92 and 16.85 +/- 2.34 l min-1 for Y and O, respectively (n.s.). The acute response to hypoxia was characterised by similar time constants (16.0 +/- 5.4 and 18.5 +/- 6.7 s) and time delays (4.8 +/- 2.1 and 4.6 +/- 1.9 s) for Y and O, respectively. Thus, the dynamic ventilatory response to acute isocapnic hypoxia is maintained into the eighth decade in a group of habitually active elderly men. Experimental Physiology (2001) 86.1, 117-126.

Attempts to control haemonchosis in grazing ewes by vaccination with gut membrane proteins of the parasite

A vaccination trial was conducted to evaluate the potential benefit of Haemonchus contortus gut membrane proteins as vaccine antigens under field conditions in Louisiana. The trial was conducted in the summer of 1996 in a flock of ewes grazing pasture naturally infected with H. contortus. Ewes were randomly assigned to three treatment groups (vaccine, adjuvant only, and saline) and fecal egg counts (FEC, measured as eggs per gram of feces), packed cell volumes (PCV), and antibody levels were monitored fortnightly for 12 weeks. It was shown by FEC that there were large individual variations in susceptibility to H. contortus in both vaccinated and non-vaccinated sheep, a finding which could have masked differences between treatments when analyzed by conventional statistical methods. Based on their egg counts before the period when the vaccination could have had an effect, all ewes were categorized as 'susceptible' or 'relatively resistant'. The significance of differences between FEC, PCV and antibody responses of vaccinated and control sheep were tested separately for the 'susceptible' and 'relatively resistant' category. The 'susceptible' vaccinates shed 65% fewer worm eggs during the period when the vaccine could have had an effect, but the difference was only significant on Week 6 post-vaccination. In these experiments, it was difficult to completely exclude the confounding effect of having 'relatively resistant' sheep in the control group. More studies are needed to further evaluate H11 and H-gal-GP antigens under field conditions.

A virtual instrument ergonomics workstation for measuring the mental workload of performing video-endoscopic surgery

The visual and physical interface imposed on the surgeon by video-endoscopic surgery (VES) increases the surgeon's mental workload. Ergonomic studies are needed to develop ways to reduce this workload. We used virtual instrumentation to devise a portable ergonomic workstation to compare the surgeon's mental workloads during simulated open surgery and VES. The system measures palmar tonic skin conductance level (SCL) and electrooculogram (EOG) and frontalis electrical activity to monitor mental stress and concentration levels. We used the system at a national surgery conference on volunteer subjects during a rest period and as they performed simulated surgery, consisting of typing knots using open and VES techniques. The subjects were asked to self-rate their levels of mental concentration and stress during these activities and reported that both progressively increased from rest to the open surgery task to the VES task. The subjects tied fewer knots during the VES than the open task, consistent with the increased demands of the VES task. The SCL progressively increased from rest to the open task to the VES task, correlating with the subjects' reported increase in mental stress level. Eye blinks and low frequency EOG activity decreased from rest to the open task, consistent with the subjects' reported increase in mental concentration level. From the open to the VES task, eye blinks and EOG activity increased, as expected given the greater demands of the VES task. High frequency frontalis activity merits further study as another indicator of the subjects' levels of mental concentration and stress.

Evaluation of immunization with gut membrane glycoproteins of Ostertagia ostertagi against homologous challenge in calves and against Haemonchus contortus in sheep

Peanut and ConA lectins were used as ligands to isolate glycoproteins from detergent extracts of adult Ostertagia ostertagi membranes. As judged by their profiles following SDS-PAGE, these fractions closely resembled the equivalents from Haemonchus contortus which are derived from the nematode intestinal cell microvillar membranes and which are highly protective when used as antigens. Groups of calves were immunized with the peanut and ConA binding fractions of Ostertagia, either as separate or pooled antigens mixed with QuilA as adjuvant. All calves, including controls immunized with adjuvant only, were challenged with a single dose of infective Ostertagia larvae and faecal egg counts were monitored for 5 weeks. In two experiments where the antigen fractions were pooled, moderate (30-50%), but statistically significant reductions in egg output were observed, but the number of worms was not diminished. No significant protection was observed in a third trial where groups of calves were immunized with peanut or ConA binding proteins given separately. Two further trials were conducted in sheep immunized with the same Ostertagia fractions but challenged with Haemonchus. Irrespective of whether they were administered separately or together, the Ostertagia antigens cross protected efficiently against Haemonchus reducing egg counts by between 81% and 97% and worm numbers by between 57% and 84%.

Localisation and characterisation of ovine immunglobulin within the sheep scab mite, Psoroptes ovis

Ovine IgG was detected in homogenates of repeatedly washed Psoroptes ovis. Some of the immunoglobulin in the homogenates was fragmented although the host IgG present in mite washings was largely intact. The host immunoglobulin was immuno-localised to the surface or cytoplasm of the gut cells of feeding stages of freshly harvested P. ovis examined by cryosectioning. A similar distribution of rabbit IgG was detected in P. cuniculi. The IgG demonstrated in the mite gut represented partially digested as well as intact immunoglobulin. The presence of intact host immunoglobulin suggests that P. ovis may be susceptible to vaccination by the gut antigen approach, a method used successfully for blood-feeding ectoparasites like Boophilus microplus.

Relative protective properties of three membrane glycoprotein fractions from Haemonchus contortus

Jacalin lectin was used as a ligand to isolate a fraction containing two distinct protective antigens from detergent extracts of membranes from Haemonchus contortus. The first antigen was identified as a complex which appeared very similar to Haemonchus galactose-containing glycoprotein (H-gal-GP), which is a previously described protective protease complex, except that it was substantially depleted of one of the main H-gal-GP components, a 230 kDa metallopeptidase-containing band. The new complex was termed Haemonchus sialylated galactose-containing glycoprotein (H-sialgal-GP), because it bound to jacalin but not to peanut lectin and only jacalin will bind the sialylated form of galactosyl (beta-1, 3) N-acetylgalactosamine. Two protection trials with sheep showed that H-sialgal-GP and H-gal-GP were equally efficacious, reducing numbers of Haemonchus eggs by between 86% and 93% and worms by between 52% and 75%, respectively. The second jacalin-binding protective antigen fraction was separated from H-sialgal-GP by ion exchange and gel filtration chromatography. It was greatly enriched for two proteins termed p46 and p52 according to their apparent molecular weights. Immunization of sheep with these proteins gave protection values of 78% for eggs and 33% for worms, which are significantly lower than those obtained with either H-gal-GP or H-sialgal-GP. N-terminal amino acid sequence data from p46 and p52 showed that both proteins were closely related to a previously described 45 kDa Haemonchus membrane protein, which had conferred protection against Haemonchus in guinea-pigs.

Cloning and characterization of a beta-galactoside-binding protein (galectin) from the gut of the gastrointestinal nematode parasite Haemonchus contortus

A cDNA encoding a beta-galactoside-binding lectin (galectin) was identified by immunoscreening a Haemonchus contortus cDNA library with antisera from lambs vaccinated with a membrane protein complex (H-gal-GP) derived from the parasites' gut. The cDNA sequence, exhibiting a tandem repeat structure and designated Hco-gal-2, showed significant levels of similarity with galectins from several species of nematode as well as mammalian galectin type 4. Native galectin was preferentially extracted from the H-gal-GP complex and also from an insoluble membrane fraction prepared from adult worms using lactose-agarose affinity chromatography. The affinity-purified material had apparent molecular mass of around 35 kDa with 3 distinct bands visible on SDS-PAGE. All 3 bands were identified as galectins by reaction with antiserum raised to recombinant Hco-GAL-2 on Western blot. To determine whether H. contortus galectins have any protective capacity against infection lambs were vaccinated with affinity-purified galectin and subsequently given a single challenge infection. Vaccination did not confer any protection against infection with H. contortus as judged by faecal egg output or worm counts.

Forty-hertz midlatency auditory evoked potential activity predicts wakeful response during desflurane and propofol anesthesia in volunteers

BACKGROUND

Suppression of response to command commonly indicates unconsciousness and generally occurs at anesthetic concentrations that suppress or eliminate memory formation. The authors sought midlatency auditory evoked potential indices that successfully differentiated wakeful responsiveness and unconsciousness.

METHODS

The authors correlated midlatency auditory evoked potential indices with anesthetic concentrations permitting and suppressing response in 22 volunteers anesthetized twice (5 days apart), with desflurane or propofol. They applied stepwise increases of 0.5 vol% end-tidal desflurane or 0.5 microg/ml target plasma concentration of propofol to achieve sedation levels just bracketing wakeful response. Midlatency auditory evoked potentials were recorded, and wakeful response was tested by asking volunteers to squeeze the investigator's hand. The authors measured latencies and amplitudes from raw waveforms and calculated indices from the frequency spectrum and the joint time-frequency spectrogram. They used prediction probability (PK) to rate midlatency auditory evoked potential indices and concentrations of end-tidal desflurane and arterial propofol for prediction of responsiveness. A PK value of 1.00 means perfect prediction and a PK of 0.50 means a correct prediction 50% of the time (e.g., by chance).

RESULTS

The approximately 40-Hz power of the frequency spectrum predicted wakefulness better than all latency or amplitude indices, although not all differences were statistically significant. The PK values for approximately 40-Hz power were 0.96 during both desflurane and propofol anesthesia, whereas the PK values for the best-performing latency and amplitude index, latency of the Nb wave, were 0.86 and 0.88 during desflurane and propofol (P = 0.10 for -40-Hz power compared with Nb latency), and for the next highest, latency of the Pb wave, were 0.82 and 0.84 (P < 0.05). The performance of the best combination of amplitude and latency variables was nearly equal to that of approximately 40-Hz power. The approximately 40-Hz power did not provide a significantly better prediction than anesthetic concentration; the PK values for concentrations of desflurane and propofol were 0.91 and 0.94. Changes of 40-Hz power values of 20% (during desflurane) and 16% (during propofol) were associated with a change in probability of nonresponsiveness from 50% to 95%.

CONCLUSIONS

The approximately 40-Hz power index and the best combination of amplitude and latency variables perform as well as predictors of response to command during desflurane and propofol anesthesia as the steady-state concentrations of these anesthetic agents. Because clinical conditions may limit measurement of steady-state anesthetic concentrations, or comparable estimates of cerebral concentration, the approximately 40-Hz power could offer advantages for predicting wakeful responsiveness.

A virtual instrument ergonomics workstation to measure surgeons' physical stress

Videoendoscopic (VES) instruments have poor force transmission properties and often require surgeons to employ awkward hand and arm positions. In order to compare the physical workload of laparoscopic surgery to open surgery, we collected long-duration EMG records from the thumb (thenar compartment) of six surgeons performing suturing and knot tying in a training box using both open and VES techniques. EMG signals were acquired using a LabVIEW Virtual Instrument and analyzed using a Modified Exposure Variation Analysis (MEVA) algorithm. Standard EMG indices and the MEVA analysis demonstrated significantly greater amplitude and duration of EMG signals using VES technique compared to open technique. Our results suggest that the use VES techniques requires a greater intensity of physical effort than open surgery techniques.

Molecular cloning and characterization of gut-derived cysteine proteinases associated with a host protective extract from Haemonchus contortus

Cysteine proteinases have been implicated in the protection conferred by vaccination with detergent-soluble extracts of Haemonchus contortus. In the present study, antisera from sheep refractory to Haemonchus challenge following vaccination with a 'proteinase-enriched' Haemonchus gut membrane extract, were employed to screen a cDNA expression library of the adult parasite. This resulted in the isolation of 3 cDNAs (designated hmcp1, 4 and 6) encoding cathepsin B-like cysteine proteinases. Immunocytochemical studies specifically localized the products of these genes to the microvillar surface of the parasite's gut and RT-PCR experiments revealed that these were developmentally regulated, being expressed exclusively during the blood-feeding parasitic stages. In addition, a generic PCR approach was adopted in order to identify the predominant cysteine proteinases in a UK strain of Haemonchus. A panel of 5 cDNAs, including hmcp1 and 4, was amplified in this way. Genomic Southern blot analysis indicated that some of these enzymes were encoded by single-copy genes, whereas others were encoded by multi-copy genes. Subsequent sequence analysis revealed that the proteases identified in this study were distinct from those previously reported in USA strains of the parasite.