Modelling for design and evaluation of industrial exoskeletons: A systematic review

Industrial exoskeletons are developed to relieve workers' physical demands in the workplace and to alleviate ergonomic issues associated with work-related musculoskeletal disorders. As a safe and economical alternative to empirical/experimental methods, modelling is considered as a powerful tool for design and evaluation of industrial exoskeletons. This systematic review aims to provide a comprehensive understanding of the current literature on the design and evaluation of industrial exoskeletons through modelling. A systematic study was conducted by general keyword searches of five electronic databases over the last two decades (2003-2022). Out of the 701 records initially retrieved, 33 eligible articles were included and analyzed in the final review, presenting a variety of model inputs, model development, and model outputs used in the modelling. This systematic review study revealed that existing modelling methods can evaluate the biomechanical and physiological effects of industrial exoskeletons and provide some design parameters. However, the modelling method is currently unable to cover some of the main evaluation metrics supported by experimental assessments, such as task performance, user experience/discomfort, change in metabolic costs etc. Standard guidelines for model construction and implementation, as well as validation of human-exoskeleton interactions, remain to be established.

Analysis of Falls from Height Variables in Occupational Accidents

Fall-from-height accidents are linked to severe and fatal consequences for impacted workers. A better understanding of the related variables is necessary to improve worker safety. This study analyzed all fall-from-height occupational accidents recorded in Spain from 2009 to 2019, selected significant variables, and evaluated the influence concerning the seriousness of the falls from height. Based on a total of 290,583 fall-from-height accidents, the study shows that a male inexperienced worker in a small company working in a non-habitual workplace is more likely to suffer fatal consequences once the accident happens. An improved knowledge of fall-from-height accidents will improve safety conditions. The workers should be trained and informed about their specific risk depending on the variables analyzed. Safety training should consider more risky profiles. Results from the current study can help identify suitable fall prevention and risk mitigation actions in safety programs for companies.

Epidemiology of fall and its socioeconomic risk factors in community-dwelling Korean elderly

Although falls in older people are a major public health problem globally, to date there are scarce reports on socioeconomic risk factors for falls. The aim of the present study was to investigate the epidemiology of fall, its associated socioeconomic risk factors and relative importance among community-dwelling Korean elderly. Secondary analysis of national survey data with 31,684 community-dwelling Korean elderly was performed. Eleven socioeconomic factors (age, gender, household type, marital status, education level, current occupation, past occupation, income, wealth, number of children, and relationship satisfaction) were selected for analysing their associations with the epidemiology of fall through complex sample analysis and logistic regressions. Results showed that 15.9%~25.1% of community-dwelling Korean elderly experienced fall yearly. The groups with significantly higher fall risks were identified as older aged, being female, not married or widowed, less educated, unemployed, and having lower relationship satisfaction. Gender (adjusted odds ratio-AOR = 1.548) and relationship satisfaction (AOR = 1.276) were the utmost important fall risk factors, indicating being older female with lower relationship satisfaction were the foremost socioeconomic characteristics for risk of falling. These findings could contribute to better understanding of the socioeconomic fall risk profiles among Korean elderly and effective strategies for fall prevention.

Emergency Evacuation Plan for Hazardous Chemicals Leakage Accidents Using GIS-based Risk Analysis Techniques in South Korea

Despite improvements in chemical safety management systems, incidents involving the release of hazardous chemicals continue to happen. In some cases, they result in the evacuation of residents. For hazardous chemical release accidents, an evacuation plan needs to be selective enough to consider both the indoor and outdoor concentrations of nearby buildings and the time in which the maximum allowable concentration may occur. In this study, a real-time risk analysis tool was developed based on the geographic information system (GIS) in order to establish the emergency response and risk communication plan for effectively assisting decision-making personnel. A selective evacuation plan was also established by a proposed assessment module considering the indoor/outdoor pollution concentration of buildings and the release duration time of chlorine gas leakage. The GIS-based simulated modules were performed based on eleven buildings of Ulsan city, located near an industrial cluster and home to a high population density. As a result of the simulated real-time risk assessment, only four buildings were affected by chlorine gas concentration according to wind direction and diffusion time. In addition, it was considered effective to establish an indoor/outdoor evacuation plan as opposed to an outdoor evacuation plan which is outside the range of the damage. Subsequently, an emergency evacuation plan was established with the concentration of a hazardous chemical according to the decision-making matrix. This study can enlighten the real-time emergency risk assessment based on GIS while effectively supporting the emergency action plans in response to the release of hazardous chemicals in clustered plants and the community.

Exergame technology and interactive interventions for elderly fall prevention: A systematic literature review

Training balance and promoting physical activities in the elderly can contribute to fall-prevention. Due to the low adherence of conventional physical therapy, fall interventions through exergame technologies are emerging. The purpose of this review study is to synthesize the available research reported on exergame technology and interactive interventions for fall prevention in the older population. Twenty-five relevant papers retrieved from five major databases were critically reviewed and analyzed. Results showed that the most common exergaming device for fall intervention was Nintendo Wii, followed by Xbox Kinect. Even though the exergame intervention protocols and outcome measures for assessing intervention effectiveness varied, the accumulated evidences revealed that exergame interventions improved physical or cognitive functions in the elderly. However, it remains inconclusive whether or not the exergame-based intervention for the elderly fall prevention is superior to conventional physical therapy and the effect mechanism of the exergaming on elderly's balance ability is still unclear.

Fatal falls and PFAS use in the construction industry: Findings from the NIOSH FACE reports

This study analyzed the Construction FACE Database (CFD), a quantitative database developed from reports of the Fatality Assessment and Control Evaluation (FACE) program conducted by the National Institute for Occupational Safety and Health (NIOSH). The CFD contains detailed data on 768 fatalities in the construction industry reported by NIOSH and individual states from 1982 through June 30, 2015. The results show that falls accounted for 42% (325) of the 768 fatalities included in the CFD. Personal fall arrest systems (PFAS) were not available to more than half of the fall decedents (54%); nearly one in four fall decedents (23%) had access to PFAS, but were not using it at the time of the fall. Lack of access to PFAS was particularly high among residential building contractors as well as roofing, siding, and sheet metal industry sectors (∼70%). Although the findings may not represent the entire construction industry today, they do provide strong evidence in favor of fall protection requirements by the Occupational Safety and Health Administration (OSHA). In addition to stronger enforcement, educating employers and workers about the importance and effectiveness of fall protection is crucial for compliance and fall prevention.

Work-related musculoskeletal disorders among construction workers in the United States from 1992 to 2014

OBJECTIVES

Examine trends and patterns of work-related musculoskeletal disorders (WMSDs) among construction workers in the USA, with an emphasis on older workers.

METHODS

WMSDs were identified from the 1992-2014 Survey of Occupational Injuries and Illnesses (SOII), and employment was estimated from the Current Population Survey (CPS). Risk of WMSDs was measured by number of WMSDs per 10 000 full-time equivalent workers and stratified by major demographic and employment subgroups. Time series analysis was performed to examine the trend of WMSDs in construction.

RESULTS

The number of WMSDs significantly dropped in the US construction industry, following the overall injury trends. However, the rate of WMSDs in construction remained higher than in all industries combined; the median days away from work increased from 8 days in 1992 to 13 days in 2014, and the proportion of WMSDs for construction workers aged 55 to 64 years almost doubled. By occupation, construction labourers had the largest number of WMSD cases, while helpers, heating and air-conditioning mechanics, cement masons and sheet metal workers had the highest rates of WMSDs. The major cause of WMSDs in construction was overexertion, and back injuries accounted for more than 40% of WMSDs among construction workers. The estimated wage loss for private wage-and-salary construction workers was $46 million in 2014.

CONCLUSIONS

Construction workers continue to face a higher risk of WMSDs. Ergonomic solutions that reduce overexertion-the primary exposure for WMSDs-should be adopted extensively at construction sites, particularly for workers with a higher risk of WMSDs.

Aging Workers and Trade-Related Injuries in the US Construction Industry

The study was designed to identify any trends of injury type as it relates to the age and trade of construction workers. The participants for this study included any individual who, while working on a heavy and highway construction project in the Midwestern United States, sustained an injury during the specified time frame of when the data were collected. During this period, 143 injury reports were collected. The four trade/occupation groups with the highest injury rates were laborers, carpenters, iron workers, and operators. Data pertaining to injuries sustained by body part in each age group showed that younger workers generally suffered from finger/hand/wrist injuries due to cuts/lacerations and contusion, whereas older workers had increased sprains/strains injuries to the ankle/foot/toes, knees/lower legs, and multiple body parts caused by falls from a higher level or overexertion. Understanding these trade-related tasks can help present a more accurate depiction of the incident and identify trends and intervention methods to meet the needs of the aging workforce in the industry.

Fatal falls in the U.S. residential construction industry

BACKGROUND

Falls from heights remain the most common cause of workplace fatalities among residential construction workers in the United States.

METHODS

This paper examines patterns and trends of fall fatalities in U.S. residential construction between 2003 and 2010 by analyzing two large national datasets.

RESULTS

Almost half of the fatalities in residential construction were from falls. In the residential roofing industry, 80% of fatalities were from falls. In addition, about one-third of fatal falls in residential construction were among self-employed workers. Workers who were older than 55 years, were Hispanic foreign-born, or employed in small establishments (1-10 employees) also had higher proportions of fatal falls in residential construction compared to those in nonresidential construction.

CONCLUSIONS

The findings suggest that fall safety within the residential construction industry lags behind commercial construction and industrial settings. Fall prevention in residential construction should be enhanced to better protect construction workers in this sector.

Study of musculoskeletal risks of the office-based surgeries

Due to the cost and time benefits associated with patients and physicians, outpatient surgeries continue to become more and more popular over time. With the increase in the number of office-based surgical procedures, the prevalence of work-related musculoskeletal disorders (WMSDs) associated with office-based surgeries has been reported. The purpose of this pilot study is to ergonomically evaluate the risk of work-related musculoskeletal disorders of physicians/surgeons performing office-based surgery (OBS). Ergonomic assessment tools included Questionnaire, the BodyMap and the Rapid Upper Limb Assessment for measuring potential ergonomic concerns. The findings have shown that the ergonomic issues of greatest concerns were the discomforts in the neck, shoulders, arms/wrists, and back. Some additional comments were provided by the participants regarding the duration of discomfort or clarification on the frequency of their body discomfort. This study suggests that there is a considerable risk of musculoskeletal injuries of physicians/surgeons performing the OBS tasks. By properly using the ergonomic assessment techniques, valuable information on ergonomic OBS workplace design and selection could assist in the early interventions of WMSD prevention.

Fatal falls from roofs among U.S. construction workers

INTRODUCTION

This study examined trends and patterns of fatal falls from roofs in the U.S. construction industry over an 18-year period (1992-2009), with detailed analysis for 2003-2009.

METHODS

Two large national datasets were analyzed: the U.S. Bureau of Labor Statistics' Census of Fatal Occupational Injuries and the Current Population Survey.

RESULTS

Roof fatalities accounted for one-third of fatal falls in construction in 1992-2009. A disproportionately high percentage (67%) of deaths from roof falls occurred in small construction establishments (1-10 employees). Roofers, ironworkers, workers employed with roofing contractors, or working at residential construction sites, had a higher risk of roof fatalities. A higher rate of roof fatalities was also found among younger (<20years) and older (>44years) workers, Hispanics, and immigrant workers.

CONCLUSION

Roof fatalities corresponded with economic cycles and differed among construction subgroups and worksites.

IMPACT ON INDUSTRY

Prevention strategies should target high-risk worker groups and small establishments.

Recent trends in the distribution of common bile duct stones in urban South Koreans

This retrospective, observational study was designed to analyse recent trends in the age distribution of westernized persons in South Korea with common bile duct stones (cholesterol, brown and black stones). Data on 253 patients who had received endoscopic surgery at a tertiary referral hospital in Daegu, the third largest South Korean city, were used to investigate the relationship between the numbers of patients with different types of common bile duct stones and age. There were strong correlations between age and the frequency of the three different types of common bile duct stones. The frequency of cholesterol stones decreased exponentially with increasing patient age, whereas the frequency of brown stones increased exponentially. Patients with black stones showed a Gaussian-like age distribution. Thus, the age-dependency of the frequency of these three common types of bile duct stones differed from one another within this patient population.

Comparison of risk factors for falls from height between commercial and residential roofers

INTRODUCTION

The purpose of this investigation was to compare commercial roofers and residential roofers in terms of their behaviors, beliefs, working conditions, and attitudes toward the use of fall protection devices, which could lead to fall accidents.

METHODS

A cross-sectional sample of 252 roofers participated in the survey in the Midwest (Wisconsin, Illinois, Michigan, Indiana, and Iowa).

RESULTS

Residential roofers were more likely to fall (prevalence ratio = 2.28, 95% CI = 1.58, 3.29) [corrected] than commercial roofers. Race/ethnicity, company size, work type, existence [corrected] of fall protection programs, enforcement of fall protection device use, actual use of fall protection devices, years of experience as a roofer, and perceived level of safety at roofing sites were [corrected] significantly associated with fall accidents.

IMPACT ON INDUSTRY

This study adds insight into fall accidents from roofs in the construction industry and provides industry-specific cautions against fall accidents that can be reflected in regulatory agency implementation.

Surface slope effects on shingling frequency and postural balance in a simulated roofing task

The purpose of this study was to investigate the influence of surface slopes (18 degrees , 26 degrees , 34 degrees ) on the maximum acceptable roof shingling frequency for males performing a simulated roof-shingling task. The psychophysical roof shingling frequency was also compared to the postural sway and trunk motion values. The maximum acceptable roof shingling frequency and selected trunk motion decreased significantly with an increase in slope. Postural sway however increased significantly with an increase in slope. The study also revealed that workers were experiencing a greater postural sway at the earlier phase of task on the steeper surface. This suggests that there might be an adaptation period associated with working on a slope and the body's ability to compensate for a loss of balance. Therefore, more emphasis should be given to the workers in this adaptation period, with additional monitoring and cautionary measures. Collectively, the findings of the study could be utilized for improving work practices on roofs, while reducing the potential risks of falls in roofing construction.

Occupational ergonomic issues in highway construction surveyed in Wisconsin, United States

This study discusses the workplace ergonomic issues in highway construction, and the safe work practices associated with the prevention of ergonomic-related injuries and illnesses in the construction field. In order to achieve the study objectives, a survey was designed and sent to Wisconsin based construction contractors. To design an adequate questionnaire, the research team first conducted a pilot study. The findings from the pilot survey provided a clear direction in creating the final survey. The survey results indicated that hand and finger injuries due to cutting operations and back injuries due to the manual handling of heavy materials to be the most frequent construction task/injury combination. All of the construction firms surveyed had a safety program; however, most of the contractors did not have a site-specific ergonomics program. The construction workers were usually walking/working on the ground, ladder and scaffold, and spent significant amount of time for the manual lifting or carrying heavy materials. The findings from this study may assist safety and health professionals in the construction industry in making effective changes for improving health and productivity.

Isolation and characterization of a cell-associated protein of Bacillus pumilus PH-01

A cell-associated protein released from Bacillus pumilus PH-01 showed an affinity for some dioxins, like 1,2,3,4-tetrachlorodibenzo-p-dioxin (TCDD) and 1,2,3,4-tetrachlorodibenzofuran (TCDF), and the concentration of the protein increased when B. pumilus PH-01 was boiled in minimal salts medium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization-mass spectrometry revealed that the boiled culture supernatant contained a major protein with a molecular mass of 5,313.4 Da. The adsorption behavior of the protein for 1,2,3,4-TCDD and 1,2,3,4-TCDF was examined by digesting it with proteinase K and trypsin, showing that the proteolyzed protein lost the ability to adsorb the compounds. The amino acid sequence of the protein was determined by automated Edman degradation and tandem mass spectrometry. A search of the protein databases showed no existence of proteins with an homologous sequence.

The effect of microfilament inhibitor on the Cryptosporidium infection in vitro

This study was focused on the effects of microfilament inhibitor, Cytochalasin D (CD) on the invasiveness of sporozoites of Cryptosporidium spp. into the host cells. MDCK and AGS cell lines were used as host cells for C. parvum and C. muris, respectively. When MDCK cells were pretreated with CD for 1 hr before inoculation of the sporozoites, C. parvum infection was significantly inhibited when compared to the control cells. These inhibitory effects of CD on the rate of infection were dose-dependent. In addition, C. muris infection was hampered when AGS cell lines were pretreated with CD. However, the capability of invasiveness of the sporozoites into the host cells was not greatly influenced by the pretreatment of sporozoites with CD before infection. These results suggest that microfilaments of host cells, rather than parasites, play an important role for the invasion of Cryptosporidium spp.

Inhibition of tumor necrosis factor-alpha-induced apoptosis by Asparagus cochinchinensis in Hep G2 cells

A human hepatoma cell line, Hep G2 cells, is a reliable system for the study of alcohol-induced hepatotoxicity. In this study, we investigated the effect of an aqueous extract of Asparagus cochinchinensis(MERRIL) (Liliaceae) roots (ACAE) on ethanol (EtOH)-induced cytotoxicity in Hep G2 cells. ACAE (1-100 microg/ml) dose-dependently inhibited the EtOH-induced tumor necrosis factor-alpha (TNF-alpha) secretion. ACAE (1-100 microg/ml) also inhibited the EtOH and TNF-alpha-induced cytotoxicity. Furthermore, we found that ACAE inhibited the TNF-alpha-induced apoptosis of Hep G2 cells. These results suggest that ACAE may prevent the EtOH-induced cytotoxicity through inhibition of the apoptosis of Hep G2 cells.

Range of motion of the wrist: implications for designing computer input devices for the elderly

PURPOSE

The purpose of this study was to report normative values of the amplitude of joint wrist motions and grip strength for older age groups.

METHOD

Volunteers. (N = 147) were divided into four age groups, 60-69, 70-79, 80-89 and 90+ years, with a total of 62 men and 85 women. Maximum range motion values were obtained for wrist flexion, extension and ulnar deviation. In addition, grip strength measures were obtained for each participant.

RESULTS

In general, the strength and ROM values for the oldest participants in this study were lower than those of the younger age group (age 60 to 69) and significantly lower than those published for subjects between 25 and 54 years of age. Furthermore, across all age groups males were significantly stronger than females. However, females tended to have greater ROM than males, particularly for wrist extension and ulnar deviations. Joint ROM and grip strength declined significantly with age for both males and females. Comparisons with published data for younger subjects (age 25-35) indicate that a 60-69 year old male, will on average experience a decline in wrist flexion, extension and ulnar deviation of 12%, 41%, and 22% respectively. By age 90, an individual may be expected to have ROM values that are only approximately 60% of an average 30 year old individual.

CONCLUSION

The results suggest that the ageing population (particularly men) may face greater difficulty using an input device such as a mouse that relies on motions of the wrist. In addition, the reduced ROM of the wrist may put the elderly at greater risk of developing cumulative trauma disorders. The implications of these findings for the design of input devices are discussed.

In vitro infection of Cryptosporidium parvum to four different cell lines

To determine a suitable condition for in vitro infection model of Cryptosporidium parvum, four different cell lines, AGS, MDCK, HCT-8 and Caco-2, were used as host cell lines which were cultured at various concentrations of added supplements. These supplement include fetal bovine serum (FBS), sodium choleate, ascorbic acid, folic acid, calcium pantothenate, para-aminobenzoic acid and pyruvate and their effects on the cell lines which were infected with C. parvum were evaluated. The results of this study showed that the AGS cell line was most susceptible to C. parvum whereas the Caco-2 cells appeared to be least susceptible to C. parvum. In regards to the serum condition, 10% FBS was suitable for the growth of AGS and HCT-8 cells, and 1% FBS was good for the growth of the MDCK cells when they were inoculated with C. parvum. Vitamins had a positive effect on the AGS cells, and pyruvate also showed positive effects on all of the cell lines except for Caco-2. Modified medium for each cell line was prepared by adding appropriate amounts of each supplement which resulted in the highest parasite infection number. Modified media increased the number of parasites infected on AGS cells to 2.3-fold higher when compared to the control media. In this study, we found that the AGS cell line was a suitable host model for evaluating C. parvum in vitro study and the media contents for the optimal infection conditions were suggested.

Can energy transfer be an indicator for DNA intercalation?

Contact energy transfer from DNA bases to various ligands, which can be represented by the ratio of the fluorescence intensity Q(lambda)/Q310nm, is measured by conventional fluorometer. 4',6-Diamidino-2-phenylindole and 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi-1H-benzimidazole can accept energy from DNA bases and exhibit the ratio Q(lambda)/Q310nm, similar to that of intercalators, although these molecules are known to bind preferentially to the minor groove of the adenine-thymine rich region of DNA. When porphyrin is intercalated in DNA or poly[d(G-C)2], the shape of the ratio Q(lambda)/Q310nm is distinct from that of the ethidium-DNA complex with two maxima at 250 nm and 280 nm. The ratio Q(lambda)/Q310nm of the porphyrin-poly[d(A-T)2] complex, in which porphyrin is known to bind 'outside' of the DNA stem, is similar to that of intercalators. Therefore, energy from excited DNA bases can be transferred not only to an intercalated ligand through direct contact but also to that bound in the minor groove. It follows from this observation that using energy transfer as a criterion for DNA intercalation requires extreme caution.

Binding mode of [ruthenium(II) (1,10-phenanthroline)2L]2+ with poly (dT*dA-dT) triplex. Ligand size effect on third-strand stabilization

The binding of homochiral [Ru(II)(1,10-phenanthroline)2L]2+ complexes [where [L = 1,10-phenanthroline (phen), dipyrido[3,2-a:2',3'-c]phenazine (DPPZ) or benzodipyrido[3,2-a:2',3'-c]phenazine (BDPPZ)] to poly(dT*dA-dT) triplex has been investigated by linear and circular dichroism and thermal denaturation. Analysis of the linear dichroism spectra indicates that the extended DPPZ and BDPPZ ligands lie approximately parallel to the base-pair and base-triplet planes consistent with intercalation which is also supported by strong hypochromism in the interligand absorption bands with either duplex or triplex. The spectral properties of any of the metal complex enantiomers were similar for binding to either duplex or triplex DNA, indicating that the third strand, which occupies the major groove of the template duplex, has little effect on the binding geometries and hence supports the hypothesis that the metal complexes all bind from the minor groove with the DPPZ and BDPPZ ligands intercalated but without intercalation in the case of [Ru(phen)3]2+. Third-strand stabilization depended on the nature of the third substituted phenanthroline chelate ligand but was not directly related to its size, with stabilizing power increasing in the order phen < BDPPZ < DPPZ. This observation further supports intercalation of the extended ligands from the minor groove of the triplex since the extended BDPPZ ligand that would protrude into the major groove of the template would have greater steric interference than DPPZ with the third DNA strand.

Impaired homeostatic mechanism of potassium handling after acute oral potassium load in diabetes mellitus

Chronic stable diabetic patients (n = 6) were compared with healthy control subjects (n = 5) after acute oral intake of 50 mEq of potassium chloride (KCl) to investigate for possible derangements of homeostatic responses for acute term (3 hrs) to acute potassium load. Plasma renin activity (PRA), plasma aldosterone (PA), and transtubular potassium concentration gradient (TTKG) known as a useful semiquantative index of distal nephron potassium secretion were measured. All the baseline parameters were comparable between diabetic and non-diabetic subjects except for significantly reduced creatinine clearance in diabetics (mean +/- SEM, 105 +/- 4 vs. 85 +/- 5 ml/min, p < 0.05). Following acute oral KCl load, the peak increases of serum potassium changes from basal levels were noted at 2 hours in both groups, but were higher in diabetic subjects (mean +/- SEM, 0.42 +/- 0.06 vs. 0.62 +/- 0.09 mEq/L). Also, 4 out of 6 diabetic subjects but none of the control subjects at 2 hours after oral KCl load became hyperkalemic ( > 5.0 mEq/L). PRA did not show any significant changes, whereas PA was increased simultaneously with increments in serum potassium in both groups, with blunted increases in the diabetics. However, TTKG was increased prominently in control subjects (8.18 from 4.98), but only slightly in diabetic subjects (4.55 from 4.18), with statistical difference between the two groups (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the ventilatory effects of etomidate and methohexital

Using a dual-isohypercapnic technique, the authors determined the effect of equipotent doses of methohexital (1.5 mg/kg) and etomidate (0.3 mg/kg) on the ventilatory response to CO2 (VERCO2) in six healthy volunteers. Speed of induction and duration of hypnosis did not differ significantly between the two drugs. Within 2 min after injection, the slope of VERCO2 decreased significantly after both methohexital (from 2.52 to a minimum of 0.15 l . min-1 . mmHg-1, P less than 0.05) and etomidate (from 2.56 to a minimum of 0.62 l . min-1 . mmHg-1, P less than 0.05); the magnitude of this depression did not differ significantly between the drugs. Methohexital also caused a significant decrease in minute ventilation at end-tidal PCO2 of 46 mmHg (VE 46) from 14.6 to 4.3 l . min-1 within 60 s after injection (P less than 0.05). In contrast, after etomidate VE 46 gradually increased from 17.9 1 . min-1 to a maximum of 31.6 l . min-1 at 3.5 min after injection (P less than 0.05); respiratory rate increased significantly, while changes in tidal volume were not significant. Effects of etomidate and methohexital on VE 46 differed significantly (P less than 0.001). These data indicate that, while etomidate and methohexital similarly depress the medullary centers that modify ventilatory drive in response to changing CO2 tensions, ventilation at any given CO2 tension is greater after etomidate than after methohexital. This indicates that etomidate may cause a CO2-independent stimulation of ventilation, suggesting its use for induction of anesthesia in cases where maintenance of spontaneous ventilation is desirable.

The effect of physostigmine on diazepam-induced ventilatory depression: a double-blind study

The authors conducted a double-blind crossover study to determine the effects of physostigmine salicylate on hyperoxic ventilatory response to carbon dioxide (VE RCO2) and on awareness in healthy subjects previously sedated with diazepam. Diazepam 0.4 mg/kg iv decreased the slope of VE RCO2 from 2.41 +/- 0.19 to 1.30 +/- 0.15 1 . min-1 . mmHg-1 (mean +/- SEM, P less than 0.001). Subsequent injection of physostigmine 2.0 mg iv was associated with a 0.20 +/- 0.28 1 . min-1 . mmHg-1 decrease in slope; this was significantly different from the 0.56 +/- 0.22 1 . min-1 . mmHg-1 increase in slope associated with saline placebo (P less than 0.05). Level of consciousness, on the other hand, increased more after physostigmine than after saline (P less than 0.01). The authors conclude that despite an apparent increase in awareness resulting from physostigmine administration, the accompanying decrease in ventilatory drive may contraindicate its use in patients who previously have received diazepam.

Typing of nontypable staphylococci by lysogeny

Strains of coagulase-positive staphylococci which were nontypable with the routine typing set of phages could be typed by lysogeny with phage-propagating strains as indicators and with ultraviolet induction. About 10% of the strains could be typed without induction. About 36% of them could be typed by this method when ultraviolet irradiation was used as an inducing agent. The phage groups from which the majority of the nontypable staphylococci originated were easily identified by this method of typing.