Comparison of Amsorb®, Sodalime, and Baralyme® Degradation of Volatile Anesthetics and Formation of Carbon Monoxide and Compound A in Swine In Vivo

Background: Consequences of volatile anesthetic degradation by carbon dioxide absorbents that contain strong base include formation of compound A from sevoflurane, formation of carbon monoxide (CO) and CO toxicity from desflurane, enflurane and isoflurane, delayed inhalation induction, and increased anesthetic costs. Amsorb(R) (Armstrong Ltd., Coleraine, Northern Ireland) is a new absorbent that does not contain strong base and does not form CO or compound A in vitro. This investigation compared Amsorb(R), Baralyme(R) (Chemetron Medical Division, Allied Healthcare Products, St. Louis, MO), and sodalime effects on CO (from desflurane and isoflurane) and compound A formation, carboxyhemoglobin (COHb) concentrations, and anesthetic degradation in a clinically relevant porcine in vivo model.

Methods: Pigs were anesthetized with desflurane, isoflurane, or sevoflurane, using fresh or partially dehydrated Amsorb(R), Baralyme(R), and new and old formulations of sodalime. Anesthetic concentrations in the fresh (preabsorber), inspired (postabsorber), and end-tidal gas were measured, as were inspired CO and compound A concentrations and blood oxyhemoglobin and COHb concentrations.

Results: For desflurane and isoflurane, the order of inspired CO and COHb formation was dehydrated Baralyme(R) >> soda-lime > Amsorb(R). For desflurane and Baralyme(R), peak CO was 9,700 +/- 5,100 parts per million (ppm), and the increase in COHb was 37 +/- 14%. CO and COHb increases were undetectable with Amsorb(R). Oxyhemoglobin desaturation occurred with desflurane and Baralyme(R) but not Amsorb(R) or sodalime. The gap between inspired and end-tidal desflurane and isoflurane did not differ between the various dehydrated absorbents. Neither fresh nor dehydrated Amsorb(R) caused compound A formation from sevoflurane. In contrast, Baralyme(R) and sodalime caused 20-40 ppm compound A. The gap between inspired and end-tidal sevoflurane did not differ between fresh absorbents, but was Amsorb(R) < sodalime < Baralyme(R) with dehydrated absorbents.     

Alexander disease: diagnosis with MR imaging

BACKGROUND AND PURPOSE: To date, the demonstration of Rosenthal fibers on brain biopsy or autopsy specimens is considered a prerequisite for a definitive diagnosis of Alexander disease. We initiated a multiinstitutional survey of MR abnormalities in both presumed and confirmed cases of Alexander disease to assess the possibility of an MR-based diagnosis. METHODS: MR imaging studies in three patients with an autopsy-based diagnosis of Alexander disease were analyzed to define MR criteria for the diagnosis. These criteria were then applied to 217 children with leukoencephalopathy of unknown origin. RESULTS: Five MR imaging criteria were defined: extensive cerebral white matter changes with frontal predominance, a periventricular rim with high signal on T1-weighted images and low signal on T2-weighted images, abnormalities of basal ganglia and thalami, brain stem abnormalities, and contrast enhancement of particular gray and white matter structures. Four of the five criteria had to be met for an MR imaging-based diagnosis. In a retrospective analysis of the MR studies of the 217 patients, 19 were found who fulfilled these criteria. No other essentially new MR abnormalities were found in these patients. In four of the 19 patients, subsequent histologic confirmation was obtained. The clinical symptomatology was the same in the patients with and without histologic confirmation and correlated well with the MR abnormalities. MR abnormalities were in close agreement with the known histopathologic findings of Alexander disease. CONCLUSION: The defined criteria are sufficient for an in vivo MR imaging diagnosis of Alexander disease; only in atypical cases is a brain biopsy still necessary for a definitive diagnosis.     

Exercise training increases heat shock protein in skeletal muscles of old rats

PURPOSE: The effects of chronic exercise training on the expression of heat shock protein (HSP) in skeletal muscle of senescent animals are unknown. Therefore, the purpose of this study was to investigate the effects of chronic exercise training on skeletal muscle HSP expression in both young and old rats. METHODS: Young adult (3 months) and old (23 months) female Fisher 344 rats were assigned to either a sedentary control or an endurance exercise trained group (N = 6 per group). Exercised animals ran (60 min.d-1, 5 d.wk-1) on a treadmill at approximately 77% VO2peak for 10 wk. After completion of the training program, the soleus (SOL), plantaris (PL), and the red (RG) and white portions (WG) of the gastrocnemius muscles were excised, and citrate synthase (CS) activity and the relative levels of HSP72 were determined. RESULTS: Training resulted in increases (P < 0.05) in VO2peak in both young (67.6 +/- 3.1 vs 86.9 +/- 1.6 mL.kg-1.min-1) and old animals (54.5 +/- 1.8 vs 68.2 +/- 2.2 mL.kg-1.min-1). Training increased CS activity and the relative levels of HSP72 (P < 0.05) in all four skeletal muscles in both young and old animals. Specifically, compared with age-matched sedentary controls, exercise training resulted in increased (P < 0.05) levels of HSP72 in skeletal muscles of both young (SOL + 22%, PL +94%, RG + 44%, WG + 243%) and old animals (SOL +15%, PL +73%, RG +38%, WG +150%). CONCLUSIONS: These findings reveal that the exercise-induced accumulation of HSP72 in skeletal muscle differs between fast and slow muscles. Further, these data indicate that the exercise-induced accumulation of HSP72 in highly oxidative skeletal muscles (SOL and RG) is similar between young and old animals. In contrast, aging is associated with a blunted expression of HSP72 in fast skeletal muscles (PL and WG) in response to chronic exercise.     

Neurotensin is an autocrine trophic factor stimulated by androgen withdrawal in human prostate cancer.

After therapeutic hormone deprivation, prostate cancer cells often develop androgen-insensitive growth through mechanisms thus far undefined. Neuropeptides have been previously implicated as growth factors in some prostate cancers. Here, we demonstrate that androgen-sensitive LNCaP human prostate cancer cells produce and secrete neurotensin following androgen withdrawal. We show that while LNCaP cells express the neurotensin receptor, only androgen-deprived cells exhibit a growth response to exogenous neurotensin. We further demonstrate that androgen-stimulated cells may be refractory to exogenous neurotensin due to androgen induction of a metalloprotease active toward neurotensin. Thus, prostate cancer cells deprived of androgen develop an alternative autocrine growth mechanism involving neurotensin.     

The diagnostic value of the fibrinogen/fibrin fragment E antigen assay in clinically suspected deep vein thrombosis

We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.     

Influenza, pneumonia, tetanus: how effective is vaccination?

The rationale for immunizing older adults with influenza, pneumococcal, and tetanus-diphtheria vaccines is derived largely from epidemiological data indicating a heightened susceptibility to these illnesses within this population. The authors provide supportive information relevant to the routine use of these vaccines in adults aged 65 or older.     

Acute Stimulant Ingestion and Neurocognitive Performance in Healthy Participants

Context:

Concussion management has become an area of great concern in athletics, and neurocognitive tests, such as Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), are commonly used as management tools. Given the restrictive nature of current management plans, anecdotal concerns have been raised about athletes trying to cheat the assessments and return to participation sooner. Stimulants have been shown to improve neurocognitive measures similar to those used in ImPACT. Therefore, they could possibly improve performance during baseline and postinjury testing.

Objective:

To examine the effects of a supplement containing stimulants on ImPACT performance.

Design:

Crossover study.

Setting:

Research laboratory.

Patients or Other Participants:

A total of 5 men (age = 20.6 ± 1.5 years, height = 176.3 ± 9.6 cm, mass = 76.9 ± 18.6 kg) and 7 women (age = 20.6 ± 1.1 years, height = 162.9 ± 7.8 cm, mass = 60.9 ± 8.2 kg) with no histories of physician-diagnosed head injury, learning disability, or attention-deficit disorder.

Intervention(s):

Participants were assessed under supplement (5.5 g of Jacked 3D, which contains caffeine and 1,3-dimethylamylamine), placebo, and control conditions separated by 1 week.

Main Outcome Measure(s):

I compared ImPACT composite scores for verbal and visual memory, visual motor speed, reaction time, impulse control, and a cognitive-efficiency index under each of the 3 conditions and assessed them 30 minutes after ingestion.

Results:

I observed a difference when comparing reaction times, as the participants reacted faster during the supplement condition (0.53 ± 0.03 seconds) than during the placebo (0.55 ± 0.03 seconds) and control (0.55 ± 0.03 seconds) conditions (F_2,22 = 4.31, P = .03). A difference also was observed for the cognitive-efficiency index, as participants scored higher during the supplement condition (0.49 ± 0.09) than during the placebo (0.41 ± 0.10) and control (0.41 ± 0.12) conditions (F_2,22 = 4.07, P = .03).

Conclusions:

Stimulant ingestion 30 minutes before testing resulted in improved memory, visual processing speed, and reaction time. However, the improvements were relatively nominal, and the question of clinical importance remains. Thus, it is unclear if stimulant ingestion would affect the return-to-participation progression.Key Words: ImPACT, caffeine, 1,3-dimethylamylamine, reaction time, processing speed

Key Points

• Acute ingestion of a nutritional supplement containing caffeine and 1,3-dimethylamylamine improved neurocognitive performance compared with the control and placebo conditions and could threaten Immediate Post-Concussion Assessment and Cognitive Testing validity.
• Clinicians should standardize and control test conditions, including controlling for caffeine and stimulant use before and during testing, to increase the validity of Immediate Post-Concussion Assessment and Cognitive Testing during baseline and postinjury testing.
• Comparing postinjury neurocognitive performance with baseline data accurately identifies cognitive changes only if both the baseline and postinjury tests are valid.

The management of mild traumatic brain injury, typically referred to in the United States as a concussion, has become an area of great concern and controversy in the athletic setting. Numerous states have adopted or are in the process of adopting legislation that mandates evaluation procedures and return-to-participation criteria for interscholastic athletics, and many sport governing bodies have adopted similar policies. Concussions are typically diagnosed after several clinical domains are assessed, including self-reported symptoms, physical signs, and cognitive functioning. Current strategies for injury management suggest that abnormalities in any 1 or more of these domains should exclude an athlete from training and competition.Many clinicians use neurocognitive tests, such as Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT; ImPACT Applications, Inc, Pittsburgh, PA), as assessment and management tools. These tests are usually administered before the sport season to obtain baseline data. If an athlete is concussed, serial evaluations are conducted postinjury to determine when neurocognitive deficits and clinical symptoms are no longer present. Researchers¹ have recommended that neurocognitive performance must revert to baseline or better before the patient returns to participation to reduce the possibility of a more serious, cumulative injury during the vulnerable recovery period.The restrictive nature of many current management plans has resulted in a longer recovery period and a delay in return to participation compared with older management plans and has created controversy. Authors^2–4 of several peer-reviewed publications have reported that athletes ranging from the high school to the professional level have stated that they have hidden or would hide the symptoms of a concussion from a health care professional or a coach primarily because they feared missing participation time or status. Similarly, anecdotal concerns have been raised about athletes trying to cheat the assessment and return to participation sooner than they should.Various stimulants, including caffeine, have been shown to improve working memory, visual information processing, and reaction time (RT), which are similar to the skills used during ImPACT.^5–7 Thus, stimulant use could possibly improve performance during neurocognitive concussion testing. However, no researchers have examined the effects of stimulant use on ImPACT or any other type of computerized neurocognitive testing. Therefore, the purpose of my study was to determine if acute stimulant ingestion would improve performance during ImPACT. I hypothesized that memory, processing speed (PS), and RT would improve after stimulant ingestion.     

An integrative review exploring the physical and psychological harm inherent in using restraint in mental health inpatient settings

In Western society, policy and legislation seeks to minimize restrictive interventions, including physical restraint; yet research suggests the use of such practices continues to raise concerns. Whilst international agreement has sought to define physical restraint, diversity in the way in which countries use restraint remains disparate. Research to date has reported on statistics regarding restraint, how and why it is used, and staff and service user perspectives about its use. However, there is limited evidence directly exploring the physical and psychological harm restraint may cause to people being cared for within mental health inpatient settings. This study reports on an integrative review of the literature exploring available evidence regarding the physical and psychological impact of restraint. The review included both experimental and nonexperimental research papers, using Cooper's (1998) five‐stage approach to synthesize the findings. Eight themes emerged: Trauma/retraumatization; Distress; Fear; Feeling ignored; Control; Power; Calm; and Dehumanizing conditions. In conclusion, whilst further research is required regarding the physical and psychological implications of physical restraint in mental health settings, mental health nurses are in a prime position to use their skills and knowledge to address the issues identified to eradicate the use of restraint and better meet the needs of those experiencing mental illness.     

Ecologic studies of Venezuelan encephalitis virus and isolations of Nepuyo and Patois viruses during 1968-1973 at a marsh habitat near the epicenter of the 1969 outbreak in Guatemala.

Ecologic studies of Venezuelan encephalitis (VE) virus at a marsh habitat near the epicenter of the 1969 outbreak in Guatemala revealed that the virus was enzootic there. VE virus was isolated yearly during 1968-1973 from sentinel hamsters exposed during the rainy seasons and from mosquitoes collected during July and August 1970. Hamsters yielded 41 strains of VE virus and virus was detected within 2 km of the edge of the marsh, in its interior, and at its western extreme 18 km from the central study site at La Avellana. One strain of virus came from a hamster that died in the dry season of January 1970. Culex mosquitoes yielded 20 strains of VE virus and Mansonia and Aedes one each. Culex (Melanoconion) and Aedes taeniorhynchus were most prevalent near the marsh. Hemagglutination-inhitibion (HI) and neutralization antibody tests of sera showed that wild terrestrial mammals (opossums and rodents), humans, and dogs, but not wild birds, were frequently infected. Seven of 16 susceptible residents of villages at the edge of the marsh developed antibodies without symptoms during an 18-month period between September 1971 and February 1973. Only 1 of 5 sentinel rabbits, and none of 30 sentinel chickens developed VE HI antibody during August-September 1971, a period when virus activity was readily detected by the use of sentinel hamsters. Five strains of group C arbovirus (one identified as Nepuyo) were recovered from sentinel hamsters during 1968 to 1970, and one strain of Nepuyo virus was isolated from the blood of a person with a febrile illness during 1972. Two strains of Patois group arboviruses were isolated from Culex mosquitoes during 1970.