Dynamics of root growth in microgravity

An experiment to study the growth of garden cress roots in microgravity is described. The experiment, denoted RANDOM, was an ESA Biorack experiment in the IML-2 flight in July 1994. In the absence of gravity, it can be anticipated that the roots would show random growth, changing their direction randomly. The hypothesis that such random growth movements occur according to random walk theory, leads to predictions as to the detailed manner in which deviations increase with time. The experiment was designed to test this random walk hypothesis. The paper concentrates on the technological aspects of studying the roots in microgravity. The development of suitable plant chambers, fitting containers developed by ESA, is described as well as the techniques used to grow the seeds between agar slices. hardware was developed to record photographically root movements between the agar slices. Photos were taken once per hour. Some plant chambers were designed to allow fixation of plant material in space. The practical solutions found using glutaraldehyde for prefixation in the Spacelab, within the restrictions given, are described. The experimental results show that the growth pattern in fact followed the prediction from the random walk approach. The average changes in the growth direction stayed constant and equal to zero during the experiment while the squared angular deviations increased proportional to time. Furthermore, plant material prefixed in orbit was permanently fixed after the flight. Light microscopy and electron microscopy pictures are shown as examples of the results achieved. The long prefixation period meant a drawback for the quality of the fixation process. However, sections suitable for study were achieved. The main goals of the RANDOM experiment were therefore achieved.

Glutaraldehyde as a fixative in bioprostheses and drug delivery matrices

The use of glutaraldehyde as a fixative in bioprostheses and drug delivery matrices is reviewed. The chemistry of glutaraldehyde cross-linking and its effect on the biological performance of a number of bioprostheses such as tissue heart valves, vascular grafts, pericardial patches, tendon grafts and drug delivery matrices are examined.

Kinetics of in vivo degradation of sepiolite-collagen complexes: effect of glutaraldehyde treatment

A kinetic study of the in vivo degradation of sepiolite-collagen complexes after subcutaneous implantation in rats was performed. A foreign-body reaction was the characteristic host tissue response against the implants. The resorption of the implanted materials was analyzed by measuring both the weight and the collagen persistences. This last was measured by using (14C)acetylated collagen, which was revealed to be not modified upon radioactive labeling, in terms of its ability to form a complex with sepiolite. The persistence of the implants is controllable by treatment of the collagen component with glutaraldehyde. Thus, for 1% glutaraldehyde-treated collagen complexes, 100% of persistence was observed after several months of implantation, this value decreasing to a few days for nontreated collagen samples. The collagen-sepiolite complex showed a low immunological response, almost null for 1% glutaraldehyde-treated collagen complexes, which was analyzed by measuring anti-collagen antibodies levels. Based on the performed studies, sepiolite-collagen complexes can be considered a resorbable material.

[Occupational allergic dermatoses in the hospital environment]

In Europe, these ten last years, we have seen the HIV epidemic's arrival and the development of the nosocomial diseases with their dangerous consequences, in hospital. The aldehyde use, with strong sensitizing power and great ability of disinfection, involve more and more numerous dermatitis. The increasing use of latex gloves is parallel to the development of different allergic diseases, of which anaphylactic shock may be one of the manifestations.

Corneal decompensation after cataract surgery. An outbreak investigation in Asia

PURPOSE

During 5 days in January 1994, two visiting expatriate ophthalmologists performed extracapsular cataract surgery on 111 patients at a nonprofit hospital in Asia. The authors investigated the development of postoperative corneal edema.

METHODS

An epidemiologic and clinical investigation was undertaken by a review of clinical charts, interview of personnel involved, an examination and interview of patients who underwent surgery, and a laboratory simulation of the disinfection procedure used.

RESULTS

Follow-up was available on 58% of the patients. The attack rate was at least 37% and likely to be approximately 64%. The attack rate was highest the first 2 days of surgery. Multivariate analysis showed that the day of surgery was the only characteristic significantly associated with the presence of corneal edema. A simulation of the disinfection technique used (soaked in 2% glutaraldehyde and rinsing) showed that significant levels of glutaraldehyde remain in instruments with small lumens after the rinse.

CONCLUSION

The epidemiologic data and simulation information are compatible; the lack of adequate rinsing of small lumen instruments soaked in glutaraldehyde is the most probable cause of this incident. Recommendations for surgeons on surgical expeditions are proposed.

Disinfectant colitis. Rinse as well as you wash

Commercially available endoscope disinfecting solutions readily cause colonic damage if allowed to contact mucosa. The two most common cleaning solutions differ in their initial toxic effect (glutaraldehyde directly injuries crypt epithelium, and hydrogen peroxide compromises mucosal stroma), but both ultimately result in tissue necrosis over time. Within 12-48 h after colonoscopy, patients show signs of bloody diarrhea, cramping, and fever--symptoms that may be confused with an infectious process. Based on a literature review and our own experimental studies, we conclude that hydrogen peroxide alone is responsible for a unique form of colitis commonly referred to as pseudolipomatosis by pathologists. This controversial lesion becomes visible as opaque plaques or pseudomembranes even while colonoscopy is in progress and is almost assuredly due to the effervescent release of molecular oxygen. Diligent rinsing is necessary to minimize patients' exposure to residual disinfecting chemicals in the endoscope. When an automatic disinfecting machine is employed, it may require strict adherence to proper maintenance and volume adjustments in the rinse cycle. Forced air drying and an additional preprocedure rinse of channels and the exterior of the scope should ensure a chemical-free examination.

The correct use of glutaraldehyde in the healthcare environment

When using and handling glutaraldehyde-based instrument sterilants, it is important to employ appropriate industrial hygiene practices such as wearing the proper personal protective equipment and installing environmental controls. Every healthcare worker who uses glutaraldehyde, or any disinfectant, should be well trained and knowledgeable about the properties of the material(s), their potential harmful effects, and the cleaning/disinfecting procedures of the healthcare facility and infection control department. Appropriate gloves, gowns, and eye protection should be available and worn. If necessary, additional ventilation should be installed to keep glutaraldehyde vapor concentrations below the Threshold Limit Value (TLV), and respiratory protective equipment should be available for emergency situations. Finally, all employees should be aware of spill clean up procedures, which should include written instructions. By keeping employees well trained and informed and by utilizing good industrial hygiene practices, the chances of overexposure to glutaraldehyde-based instrument sterilants will be minimized, and working conditions will be comfortable and safe.

Glutaraldehyde colitis following endoscopy: clinical and pathological features and investigation of an outbreak

Although potentially noxious compounds are used routinely to disinfect endoscopes, reports of their inadvertent introduction to the gastrointestinal tract, usually attributed to the retention of disinfectant within endoscope channels, are rare. This case report describes the clinical features of glutaraldehyde-induced colitis and the pathology of the mucosal injury in four patients, in at least one of whom the disinfectant was not retained in the endoscope itself. Within 3 months, three patients experienced severe acute proctocolitis < 6 hours after a sigmoidoscopy showing no abnormalities, performed in a small endoscopy unit. Investigation of the unit's protocols suggested that the most likely cause was retention of 2% glutaraldehyde disinfectant in the endoscope channels, and changes were made to prevent this. When a fourth case occurred 5 months later, the source of the glutaraldehyde was found to be the tubing connecting water bottles to the endoscopes, which was disinfected rigorously but flushed inconsistently between cases. Glutaraldehyde-induced colitis seems similar to ischemic colitis in biopsy specimens and cannot be diagnosed by histological analysis alone. Acute colitis occurring within 24 hours of a colonoscopy showing no abnormalities should be considered iatrogenic and should lead to an investigation of procedures in use for cleaning and disinfecting endoscopic equipment.

Glutaraldehyde colitis: radiologic findings

PURPOSE

Two percent glutaraldehyde on colonic mucosa may result in a toxic colitis, and the clinical features may mimic those of colonic ischemia. The study was performed to determine the radiologic appearance of glutaraldehyde-induced toxic colitis.

MATERIALS AND METHODS

A retrospective review was performed with the clinical and imaging findings in four patients with glutaraldehyde-induced colitis seen during a 6-year period.

RESULTS

Patients developed a self-limited syndrome of cramps and abdominal pain, tenesmus, and rectal bleeding within 48 hours of uncomplicated sigmoidoscopy or colonoscopy. Sample cultures excluded enteric pathogens. Computed tomography (CT) demonstrated circumferential thickening of the colonic wall in a left-sided distribution in all patients. Heterogeneous mural enhancement (target-sign appearance) was noted in two patients. Follow-up CT studies confirmed resolution of mural wall thickening with conservative management.

CONCLUSION

The clinical and radiologic features of glutaraldehyde-induced toxic colitis may mimic those of colonic ischemia. This complication should be suspected in patients who develop hemorrhagic colitis immediately after undergoing colonoscopy.

Occupational asthma due to glutaraldehyde and formaldehyde in endoscopy and x ray departments

BACKGROUND

Glutaraldehyde is the best disinfectant for fibreoptic endoscopes. It is also used in the processing of x ray films. A number of studies have reported eye, nose, and respiratory symptoms in exposed workers. Three individual case reports of occupational asthma in endoscopy workers and a radiographer have also been published. We describe a further seven cases of occupational asthma due to glutaraldehyde in endoscopy and x ray departments, together with exposure levels measured during the challenge tests and in 19 endoscopy and x ray departments in the region.

METHODS

Eight workers were referred for investigation of suspected occupational asthma following direct or indirect exposure to glutaraldehyde at work. They were investigated by serial measurements of peak expiratory flow (PEF) and specific bronchial provocation tests. Glutaraldehyde levels were measured using personal and static short and longer term air samples during the challenge tests and in 13 endoscopy units and six x ray darkrooms in the region where concern about glutaraldehyde exposure had been expressed. Three of the workers investigated with occupational asthma came from departments where glutaraldehyde air measurements had been made; the others came from other hospitals or departments.

RESULTS

The diagnosis of occupational asthma was confirmed in seven workers, all of whom had PEF records suggestive of occupational asthma and positive specific bronchial challenge tests to glutaraldehyde. Bronchial provocation testing was negative in one worker who was no longer exposed and who had a less clearcut history of occupational asthma. Three workers also had a positive specific bronchial challenge to formaldehyde. The mean level of glutaraldehyde in air during the challenge tests was 0.068 mg/m3, about one tenth of the short term occupational exposure standard of 0.7 mg/m3. The levels obtained in the challenge chamber were similar to those measured in 13 endoscopy suites and six x ray darkrooms where median short term levels were 0.16 mg/m3 during decantation in endoscopy suites and < 0.009 mg/m3 in darkrooms.

CONCLUSIONS

Glutaraldehyde can cause occupational asthma. The exposure levels measured in the workplace suggest that sensitisation may occur at levels below the current occupational exposure standard.

Glutaraldehyde--controlling the risk to health

The Control of Substances Hazardous to Health Regulation 1988 (COSHH) is one of the most important pieces of health and safety legislation to affect the workplace since the Health and Safety at Work Act of 1974. The regulations require that the exposure to all hazardous chemicals and micro-biological agents be reviewed and measures put in place to control the risk to health. An evaluation survey that reported in mid-1993 showed many workplaces had simply collected data sheets on hazardous agents but failed to carry out the all important next steps to evaluate the risks arising from the hazards, to monitor exposure and implement control measures to institute health surveillance where appropriate to inform and train employees. The lack of effective control of the exposure to glutaraldehyde in endoscope cleaning activity was highlighted, along with other deficiencies, in a recent inspection by the Health and Safety Executive of an NHS Trust in East Anglia. It is recognised that glutaraldehyde has posed particular problems in the operating theatre environment of the NHS.

Outbreak of glutaraldehyde-induced proctocolitis

BACKGROUND

An outbreak of hemorrhagic proctocolitis occurred after the introduction of 2% glutaraldehyde as a disinfectant for colonoscopes. An inadequate rinsing procedure was detected. Recent studies have pointed to glutaraldehyde as an irritant potentially capable of inducing colitis. This study aimed to measure retrospectively the occurrence of proctocolitis after colonoscopy in persons exposed to glutaraldehyde used as a disinfectant for colonoscopes, and to compare this rate with that in patients exposed to the previous cleaning procedure.

METHODS

Colonoscopic procedures were randomly selected during the period when glutaraldehyde was used, as well as during the previous period, when a detergent was used. Patients were asked to respond to a questionnaire during a telephone interview, in search of symptoms compatible with proctocolitis after colonoscopy.

RESULTS

Of the 400 colonoscopic procedures selected during each of the glutaraldehyde and the detergent periods, respectively 299 and 242 were evaluable. According to different nonexclusive definitions, we observed in the glutaraldehyde period higher frequencies of proctocolitis (at least five stools/day; 14/299 vs 3/242, p = 0.02), severe proctocolitis (> 10 stools/day; 10/299 vs 1/242, p = 0.04), and severe hemorrhagic proctocolitis (6/299 vs 0/242, p = 0.04). Younger age was associated with proctocolitis only during the glutaraldehyde period (p = 0.0008). No pathogen was demonstrated in the only two patients who had stool cultures. The median incubation after colonoscopy was 4 hours (range 0 to 24 hours) and the symptoms lasted 30 hours (range 6 to 216 hours). No patient had fever, and the illness resolved spontaneously in all cases.

CONCLUSION

Inadequate rinsing of colonoscopes after immersion in glutaraldehyde may result in proctocolitis, presumably caused by direct action on the mucosa.

Endoscope-induced colitis: description, probable cause by glutaraldehyde, and prevention

Six cases of acute, self-limited colitis that occurred after screening flexible sigmoidoscopy were deduced to be iatrogenic, probably caused by glutaraldehyde residues in the endoscopes after disinfection in an automatic disinfecting machine. The concentration of these residues was indirectly estimated by conductivity measurements of electrolyte concentration in the rinse-water tank of the disinfecting machine during and after five cycles and also in fluid remaining on the surface of the endoscopes and in the endoscope channels. After five cycles, residues in both the rinse water and fluid in the endoscope channels contained the equivalent of 0.2% glutaraldehyde. This was the result of a combination of technical and human errors. It can be prevented by changing the rinse water after each cycle, using forced air to dry the instruments, and washing the endoscopes before use. Users of the automatic disinfecting machine should be aware of the potential accumulation of toxic levels of residues that remain in endoscopes after disinfection.