Effects of six weeks of chronic sleep restriction with weekend recovery on cognitive performance and wellbeing in high-performing adults

Chronic sleep loss is associated with escalating declines in vigilant attention across days of sleep restriction. However, studies exceeding two weeks of chronic sleep loss are scarce, and the cognitive performance outcomes assessed are limited. We assessed the effects of six weeks of chronic sleep restriction on a range of cognitive domains in 15 high-performing individuals (38.5±8.2 years, 6 women) confined to small space in groups of four. Sleep opportunities were limited to 5h on weekdays and 8h on weekends. Individual sleep/wake patterns were recorded with actigraphy. Neurobehavioral performance was assessed in evenings with Cognition, a computerized battery of ten tests assessing a range of cognitive domains. There were some small to moderate effects of increasing sleep debt relative to pre-mission baseline, with decreases in accuracy across cognitive domains (standardized β=0.121, p=0.001), specifically on tests of spatial orientation (β=0.289, p=0.011) and vigilant attention (β=0.688, p<0.001), which were not restored by two nights of weekend recovery sleep. Cognitive and subjective decrements occurred despite occasional daytime napping in breach of study protocol, evening testing around the circadian peak, and access to caffeine before 14:00. Sensorimotor speed, spatial learning and memory, working memory, abstraction and mental flexibility, emotion identification, abstract reasoning, cognitive throughput and risk decision making were not significantly affected by sleep debt. Taken together with modest lower subjective ratings of happiness and healthiness, these findings underline the importance of sufficient sleep, on both an acute and chronic basis, for performance in selected cognitive domains and subjective wellbeing in operationally-relevant environments.

0187 The Effects of Nocturnal Aircraft Noise on Self-Reported Sleep

Introduction

Nocturnal traffic noise can fragment sleep through cortical arousals and induce self-reported sleep disturbance. Here we present data gathered around Atlanta International Airport in a pilot field study on the effects of aircraft noise on sleep.

Methods

N=34 subjects participated in a five night in-home study. Every night, subjects recorded noise inside their bedroom, and completed questionnaires the following morning containing items on sleep latency; number of awakenings; sleepiness (Stanford Sleepiness Scale); 11-point scales on sleep quality, tiredness, ease of falling asleep and calmness or restlessness of sleep; and a 5-point scale on sleep disturbance by noise. We analyzed the effect of both the average (LAEq,sleep) and maximum (LAS,max,sleep) aircraft noise level during a subject’s sleep period for each questionnaire outcome in repeated measures multiple regression adjusted for the number of aircraft noise events during sleep, sex, age, and if the window was open or closed.

Results

A total of 165 sleep questionnaires (97.1% of expected) were completed. Self-reported awakenings increased by n=0.051 per decibel (dB) LAS,max,sleep (p&lt;0.001). An increase in LAS,max,sleep was associated with a significant increase in tiredness (0.118/dB, p=0.005). There was a significant effect of sex on tiredness in the LAEq,sleep model, whereby men were less tired than women. There were no significant effects of LAEq,sleep on any questionnaire outcomes.

Conclusion

There was some evidence for adverse effects of aircraft noise on self-reported sleep outcomes. Effects were predominantly found for maximum rather than average noise exposure during the sleep period, stressing the importance of individual noise events for sleep. A larger-scale, adequately powered National Sleep Study will be conducted to better understand the observed effects.

Support

This research was funded by the U.S. Federal Aviation Administration Office of Environment and Energy through ASCENT, the FAA Center of Excellence for Alternative Jet Fuels and the Environment, project 017 through FAA Award Number 13-C-AJE-UPENN-011 under the supervision of Natalia Sizov. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.

0282 Correlation Between Sleep Depth in the Right and Left Cerebral Hemispheres Following Sleep Deprivation, Restriction or Noise Exposure

Introduction

The Odds-Ratio-Product (ORP) is a highly-validated continuous index of sleep depth (range 0=deep sleep; 2.5=full wakefulness). ORP values fluctuate within this range as sleep state changes between wake and different sleep stages. In healthy non-sleep deprived adults, intra-class correlation coefficient of concurrent right vs. left ORP values (R / L coefficient) is typically &gt;0.80. In a recent study R / L coefficient was markedly reduced in many critically-ill patients and these patients failed to be weaned from mechanical ventilation. Given the high prevalence of sleep loss in such patients we hypothesized that reduction in R/L coefficient might result from sleep loss. This retrospective EEG analysis of data from 3 independent research studies investigated if R / L coefficient decreases in pure models of sleep deprivation, restriction or noise exposure during sleep in healthy subjects.

Methods

Polysomnograms were obtained from three studies: A) 200 subjects who underwent 36 hours of total sleep deprivation; B) 21 subjects who underwent 4 consecutive nights of sleep restriction (5 hrs. / night); C) 72 subjects who were exposed to intermittent traffic noise events with maximum sound pressure levels ranging from 45–65 dB(A) for 10 consecutive nights. For study A, R / L coefficient was calculated from pre- and post-deprivation sleep studies and the two values were compared. For study B, coefficient was calculated at baseline and in each restriction night. For study C, the coefficient was calculated in each of the 10 exposure nights and the slope of the change was calculated.

Results

In study A, the coefficient decreased from 0.82±0.12 at baseline to 0.74±0.16 after sleep deprivation (p &lt 0.0001). In study B, the coefficient decreased from 0.83±0.11 at baseline to 0.75±0.15 on the 4th restriction night (p &lt 0.01). In study C, coefficient decreased at a rate of 0.003±0.001 per exposure night (p &lt 0.001).

Conclusion

The correlation between sleep depth in the right and left hemispheres deteriorates following sleep deprivation, restriction or noise-induced sleep fragmentation.

Support

NIH P50 HL060287

Phenotypic and genotypic profiling of antimicrobial resistance in enteric Escherichia coli communities isolated from finisher pigs in Australia

OBJECTIVE

To assess herd-to-herd variation in antimicrobial resistance phenotypes and associated antimicrobial resistance genes (ARGs) in faecal commensal Escherichia coli communities isolated from Australian slaughter-age pigs.

METHODS

Hydrophobic grid-membrane filtration (HGMF) was used to screen populations of E. coli isolated from faecal samples obtained from pigs prior to or at slaughter. Multiplex PCRs were applied to the pooled DNA extracted from the samples to identify specific ARGs.

METHODS

Pooled faecal samples from 30 finishers, from 72 different Australian pig farms, produced 5003 isolates for screening. HGMF techniques and image analysis were used to confirm E. coli resistance phenotypes to four antimicrobial agents (ampicillin, gentamicin, florfenicol and ceftiofur) using selective agars. Multiplex PCRs were performed on DNA from pooled samples for 35 ARGs associated with seven chemical classes.

RESULTS

The prevalence of E. coli isolates showing no resistance to any of the drugs was 50.2% (95% confidence interval (CI) 41.8-58.6%). Ceftiofur resistance was very low (1.8%; CI 0.8-3.9%) and no ARGs associated with 3rd-generation cephalosporin resistance were detected. By contrast, ampicillin (29.4%, CI 22.8-37.0%), florfenicol (24.3%, CI 17.8-32.3%) and gentamicin (CI 17.5%, 10.7-27.2%) resistance prevalence varied greatly between farms and associated ARGs were common. The most common combined resistance phenotype was ampicillin-florfenicol.

CONCLUSION

The use of registered antimicrobials in Australian pigs leads to the enteric commensal populations acquiring associated ARGs. However, despite a high intensity of sampling, ARGs imparting resistance to the critically important 3rd-generation cephalosporins were not detected.

TGF-beta1 interactome: metastasis and beyond

The ubiquitous cytokine transforming growth factor-beta1 (TGF-beta1) is one of the most potent metastatic inducers. Functional interactomic mapping using high-throughput proteomic and genomic data provides valuable insights into the regulation of tumor suppressive and metastatic attributes of TGF-beta1. Polarity changes of the TGF-beta1 interactome at a given time contributes to these contrasting effects. Differential expression profiles of pivotal interactomic nodes contribute to these polarity changes. These insights are of immense value in the development of effective cancer therapeutics. Moreover, TGF-beta1 interactomic nodes are useful in discovering novel cancer biomarkers. This review describes an initial version of the TGF-beta1 interactome in relation to tumor progression and metastasis. Thus, this review embodies an important step towards the mapping of comprehensive and individualized TGF-beta1 interactomes that will assist in the development of personalized cancer therapeutics.

ST. LOUIS ENCEPHALITIS : TRANSMISSION OF VIRUS TO CHICKENS BY INFECTED MITES DERMANYSSUS GALLINAE AND RESULTING VIREMIA AS SOURCE OF VIRUS FOR INFECTION OF MITES

Transmission of the virus of St. Louis encephalitis to normal chickens by the bite of infected mites (Dermanyssus gallinae) has been demonstrated. Both experimentally infected and naturally infected mites were shown to be capable of transferring the virus of St. Louis encephalitis to chickens by bite. Virus is present in the blood of such chickens in small amounts, so that demonstration of viremia was possible only by utilizing chorioallantoic passage in hens' eggs. However, there is sufficient virus present in the blood for uninfected chicken mites to acquire the virus by feeding on chickens in which viremia has resulted from previous bite of infected mites. Thus it has been shown that the arachnid vector Dermanyssus gallinae is capable of transmitting the virus of St. Louis encephalitis to normal chickens by bite and that such chickens can serve as a source of virus for uninfected mites.

THE VISCERAL LESIONS PRODUCED IN MICE BY THE SALIVARY GLAND VIRUS OF MICE

Extensive visceral lesions containing intranuclear inclusions have been produced in mice by intraperitoneal and intracerebral inoculations of the homologous salivary gland virus. Rarely small pancreatic lesions containing inclusions have been encountered 2 weeks after subcutaneous inoculation. Many of the animals injected intraperitoneally died between the 4th and 7th day after inoculation. In spite of the extensive lesions produced in the liver and spleen, the virus could not be transferred with an emulsion of these organs.

INFLUENCE OF AGE ON SUSCEPTIBILITY OF MICE TO ST. LOUIS ENCEPHALITIS VIRUS AND ON THE DISTRIBUTION OF LESIONS

1. Young mice are more susceptible than older mice to the virus of St. Louis encephalitis inoculated intraperitoneally, but with virus inoculated intracerebrally or intranasally, there is no significant age difference in susceptibility. The greatest change in the resistance to the virus inoculated intraperitoneally occurs between the 2nd and 3rd weeks of life. 2. The distribution of the lesions of St. Louis encephalitis in the C.N.S. of young and of old animals following intraperitoneal inoculation indicates that the virus may reach the brain either by the ascending pathway from the spinal cord or by the olfactory pathway irrespective of the age of the animal. However the ascending pathway is most frequently concerned. 3. The distribution of lesions does not offer evidence that the virus enters the C.N.S. of young animals directly from the blood stream following intraperitoneal inoculation. 4. Although widespread lesions occur earlier in the C.N.S. of young mice than in that of older mice inoculated intraperitoneally with large doses of virus, this fact is not satisfactorily explained by assuming the more rapid increase of the virus in the C.N.S. of young animals, since the latter are not more susceptible to virus inoculated directly into the brain. 5. The observations can be explained by the hypothesis that a greater amount of virus survives and reaches the portals of the C.N.S. in young animals following intraperitoneal inoculation and that this is an important factor in the influence of age on susceptibility to the virus.

Antimicrobial resistance and virulence gene profiles in multi-drug resistant enterotoxigenic Escherichia coli isolated from pigs with post-weaning diarrhoea

This study aimed to characterize antimicrobial resistance and virulence genes in multi-drug resistant enterotoxigenic Escherichia coli (ETEC) isolates (n=117) collected from porcine post-weaning diarrhoea cases in Australia (1999-2005). Isolates were serotyped, antibiogram-phenotyped for 12 antimicrobial agents and genotyped by PCR for 30 plasmid-mediated antimicrobial resistance genes (ARGs), 22 intestinal and 38 extraintestinal E. coli virulence genes (VGs). Nine serogroups were identified, the most prevalent being O149 (46.2%), O141 (11.2%) and Ont (31.6%). None of the isolates showed resistance to ceftiofur or enrofloxacin and 9.4% were resistant to florfenicol. No corresponding extended-spectrum/AmpC β-lactamase, fluoroquinolone or floR ARGs were detected. An antimicrobial resistance index (ARI) was calculated from the combined data with a weighting for each antimicrobial agent dependent upon its significance to human health. Serogroup O141 isolates had a significantly higher ARI due to an elevated prevalence of aminoglycoside ARGs and possession of more virulence genes (VGs), including ExPEC or EHEC adhesins (bmaE, sfa/focDE, fimH, ihA) in toxin-producing strains that lacked the normally associated F4 and F18 fimbriae. Few associations between ARGs and VGs were apparent, apart from tetC, sfa/focDE and ompT which, for a sub-set of O141 isolates, suggest possible plasmid acquisition from ExPEC. The multi-drug resistant ETEC ARG/VG profiles indicate a high probability of considerable strain and plasmid diversity, reflecting various selection pressures at the individual farm level rather than emergence and lateral spread of MDR resistant/virulent clones.

Inhibition of progenitor cell proliferation in the dentate gyrus of rats following post-weaning lead exposure

Although lead is a potent developmental neurotoxin, the effects of postnatal lead exposure on progenitor cell proliferation in the hippocampus has not been examined. Postnatal day 25 rats were fed a lead containing diet (1500 ppm lead acetate) for 30-35 days and administered bromodeoxyuridine (BrdU, 50 mg/kg, i.p.) during the last 5 days of lead exposure. Animals were killed 24 h after the last BrdU injection. Proliferation of new cells in the subgranular zone and dentate gyrus was significantly decreased in lead-exposed rats compared to control animals that ate a similar diet devoid of lead. These results suggest that postnatal lead exposure can have significant deleterious effects on progenitor cell proliferation and thus the structure and function of the hippocampus.

Treatment of osteoporosis: missed opportunities in the hospital fracture clinic

AIM

To identify what proportion of patients who, having sustained an initial distal radial fragility fracture and a subsequent femoral neck fracture, had had their osteoporosis addressed in the interval between the two events.

PATIENTS AND METHODS

The hospital electronic information system was used to identify all patients aged over 50 years treated for a distal radial fracture, in our fracture clinic, between 1995-2000. In addition all patients admitted to our hospital, during the same time period, with a femoral neck fracture were identified.

RESULTS

A study cohort of 74 patients were identified. The proportion of patients who received investigation of, or treatment for, osteoporosis between their wrist and femoral neck fracture was 8% whereas 84% did not.

CONCLUSIONS

Current mechanisms for identifying patients with osteoporosis before they sustain a femoral neck fracture are inadequate.

Clinical and economic benefits of ramipril: an Australian analysis of the HOPE study

BACKGROUND

The Heart Outcomes Prevention Evaluation (HOPE) study has demonstrated that ramipril 10 mg/day for 5 years in an at-risk population results in clinically and statistically significant reductions in the occurrence of cardiovascular death, myocardial infarction (MI), stroke and revascularization procedures. The likely impact of the intervention in Australia, in terms of the number of potential events avoided and the cost per life-year saved, has previously not been determined.

AIMS

To assess the clinical and economic impacts of the use of daily ramipril in the Australian at-risk population from the perspective of the public health-care budget.

METHODS

The clinical benefits were calculated from endpoints used in the trial, which were converted to the 'number needed to treat'. These were then applied to the at-risk population, which was determined nationally from the relevant Australian statistics. The result of this calculation is the potential number of events avoided in Australia. The economic benefits were established by undertaking an incremental cost-effectiveness analysis. The economic model considered the clinical benefits and the costs (and cost offsets) arising from ramipril 10 mg/day therapy for 5 years. Life-years saved was determined by calculating the difference in total years survived between the ramipril and control arms of the study. Net costs divided by life-years saved is the cost per life-year saved, and this is reported in Australian dollars as the incremental cost effectiveness.

RESULTS

The clinical benefits over a 5-year period were expressed as the number of potential events avoided and comprised approximately: 9188 strokes; 14 658 MI; 14 317 revascularization procedures; and 12,534 cardiovascular-related deaths, nationally. The incremental cost-effectiveness analysis showed the estimated cost per life-year saved to be 17,214 Australia dollars.

CONCLUSION

The use of ramipril 10 mg/day over a 5-year period in the at-risk Australian population could prevent many thousands of cardiovascular events, including 12,534 cardiovascular-related deaths. The cost per life-year saved compares favourably to other health care interventions.

Fracture of an elastic humeral nail. A case report

The use of elastic intramedullary nails for the treatment of diaphyseal fractures of the humerus has been associated with few complications. We report a fracture of an elastic Marchetti-Vicenzi nail used to treat a pathological fracture of the humerus. The failure of the intramedullary nail followed low-energy trauma and was presumably the end result of metal fatigue, as the original fracture had only healed after 13 months.

Lacrimal fossa block: an audit of a minimally invasive regional anaesthetic technique for endoscopic dacryocystorhinostomy (DCR)

The lacrimal fossa block (LFB), a new development to provide regional anaesthesia for endoscopic dacryocystorhinostomy, is reported. Cadaveric study showed that the block needle, inserted as described, made direct contact with the periosteum of the frontal process of the maxilla within the lacrimal fossa. This technique enables both relevant divisions of the trigeminal nerve to be anaesthetized through a single entry site and, as this injection is confined to the anterior part of the orbit, ocular complications are minimized. An audit of 66 patients has shown that this technique, combined with standard intranasal local anaesthesia, provides good intraoperative analgesia, causes minimal diplopia and has a high level of patient acceptability.

Automated Portable Test (APT) System: overview and prospects

The Automated Portable Test (APT) System is a notebook-sized, computer-based, human-performance and subjective-status assessment system. It is now being used in a wide range of environmental studies (e.g., simulator aftereffects, flight tests, drug effects, and hypoxia). Three questionnaires and 15 performance tests have been implemented, and the adaptation of 30 more tests is underway or is planned. The APT System is easily transportable, is inexpensive, and has the breadth of expansion options required for field and laboratory applications. The APT System is a powerful and expandable tool for human assessment in remote and unusual environments.

Implementation of the STOP protocol for Stroke Prevention in Sickle Cell Anemia by using duplex power Doppler imaging

PURPOSE

To compare the results of the nonduplex ultrasonography (US) Stroke Prevention Trial in Sickle Cell Anemia (STOP) with those of transcranial duplex power Doppler US by using the STOP protocol and to correlate abnormal transcranial Doppler findings with magnetic resonance (MR) imaging and MR angiographic findings.

MATERIALS AND METHODS

One hundred twenty-five asymptomatic patients aged 2-16 years with sickle cell anemia or sickle cell-beta thalassemia were examined by using transcranial duplex power Doppler US with a 2.5-MHz transducer and classified according to STOP criteria. The results were compared with those obtained in the nonduplex STOP study. Eight of 10 patients with abnormal results, as well as one who had normal results and a subsequent stroke, were examined with MR imaging and MR angiography.

RESULTS

Ten (8.0%) patients were judged to have abnormal findings by using the duplex Doppler US and STOP criteria compared with 9.4% of patients in the nonduplex US STOP study. Of the eight patients with abnormal transcranial Doppler US results who underwent MR imaging and MR angiography, six had abnormal MR imaging findings and all eight had abnormal MR angiographic findings.

CONCLUSION

The STOP protocol can be reproduced by using duplex power Doppler US. Abnormal results with the STOP criteria strongly suggest vascular abnormality.

The life cycle of actin patches in mating yeast

Actin patches are core components of the yeast actin cytoskeleton that undergo redistribution during establishment of cell polarity. Using 4D imaging, we observe the life cycle of actin patches in living yeast for the first time. We observe assembly of actin patches at sites of polarized growth, and disassembly of actin patches concomitant with movement away from those sites. The total lifetime of an actin patch is 10.9+/-4.2 seconds. These findings indicate that actin patches are labile structures, and that the localization of actin patches during establishment of cell polarity occurs by assembly of these structures at sites of polarized cell surface growth. These findings were confirmed and extended by analysis of myosin I proteins and their receptor, verprolin, proteins implicated in actin assembly in yeast. Deletion of type I myosins or their receptor has no effect on the velocity of actin patch movement. However, these mutants show a 65% reduction in number of patch movements and a three-fold increase in patch lifetime. Finally, the actin patch resident proteins Abp1p, fimbrin, and Arp2p show normal association with actin patches in myosin I and verprolin mutants. However, cofilin accumulates in abnormal ‘bars’ of G-actin in myo3(Δ),myo5(Δ) and vrp1(Δ) strains, and Las17p/Bee1p is not associated with actin patches in vrp1(Δ) strains. These findings imply a multi-step process for actin patch assembly. Early events in this process, including assembly of Abp1p, fimbrin and Arp2p with F-actin, can occur throughout the cell and do not require myosin I proteins or their receptor. Later events in this process are myosin I-dependent, and are required for assembly of actin patches at sites of polarized cell surface growth. http://www.biologists.com/JCS/movies/jcs1990.html

An outbreak of Yersinia enterocolitica O:8 infections associated with pasteurized milk

In October 1995, an outbreak of Yersinia enterocolitica O:8 infections occurred in the Upper Valley of Vermont and New Hampshire. Ten patients were identified, median age 9 years (range, 6 months-44 years). Three patients were hospitalized; 1 underwent an appendectomy. Consumption of bottled pasteurized milk from a local dairy was associated with illness (matched odds ratio undefined; lower 95% confidence interval, 1.9). No deficiencies in pasteurization procedures or equipment were detected. Y. enterocolitica O:8 was isolated from 1 raw-milk sample and from a fecal sample from 1 dairy pig. The route of contamination was not determined; this outbreak likely resulted from postpasteurization contamination of milk. Dairy pigs were the most likely source of contamination. Milk bottles were likely contaminated by rinsing with untreated well water prior to filling or by other environmental routes. Educating dairy owners about Y. enterocolitica and postpasteurization contamination is necessary to prevent further outbreaks.

Hepatitis B virus transmission in an elementary school setting

CONTEXT

The risk of transmission of hepatitis B virus (HBV) in day care centers and schools is low.

OBJECTIVE

To investigate the source of HBV transmission for an elementary school teacher with acute hepatitis B.

DESIGN

Serologic survey for HBV infection among elementary school students, school staff, and household members of an HBV-infected teacher and student.

SETTING

General community and elementary school.

PATIENTS

Elementary school students and staff members and household members of an HBV-infected teacher.

MAIN OUTCOME MEASURES

Elementary school students, school staff, and household members of an HBV-infected teacher were tested for markers of HBV infection. Samples positive for hepatitis B surface antigen (HBsAg) were tested for HBsAg subtype using monoclonal antibodies and examined for HBV DNA homology by polymerase chain reaction techniques.

RESULTS

An HBV-infected student and the teacher were found to have the same HBV subtype (ayw1-2) and to have identical HBV DNA sequences. The teacher reported none of the usual risk factors for acquiring HBV infection, and none of her family members had been infected prior to her illness. The specific means of HBV transmission from student to teacher was not identified. Of 108 total children in the same grade as the HBV-infected student, 102 (94%) were tested for serologic markers of HBV infection, and none was positive.

CONCLUSIONS

This investigation documented transmission from an HBV-infected student to a teacher in an elementary school setting without a reported overt percutaneous or permucosal exposure to blood or infectious body fluids. Transmission of HBV to other students or staff members in the school was not observed.

Predicting rodent carcinogenicity from mutagenic potency measured in the Ames Salmonella assay

Many in vitro tests have been developed to identify chemicals that can damage cellular DNA or cause mutations, and secondarily to identify potential carcinogens. The test receiving by far the most use and attention has been the Salmonella (SAL) mutagenesis test developed by Ames and colleagues [(1973): Proc Natl Acad Sci USA 70:2281-2285; (1975): Mutat Res 31:347-364], because of its initial promise of high qualitative (YES/NO) predictivity for cancer in rodents and, by extension, in humans. In addition to the initial reports of high qualitative predictivity, there was also an early report by Meselson and Russell [in Hiatt HH et al (1977): "Origins of Human Cancer, Book C: Human Risk Assessment," pp 1473-1481] of a quantitative relationship between mutagenic potency measured in SAL and carcinogenic potency measured in rodents, for a small number of chemicals. However, other reports using larger numbers of chemicals have found only very weak correlations. The primary purpose of this study was to determine whether mutagenic potency, as measured in a number of different ways, could be used to improve predictivity of carcinogenicity, either qualitatively or quantitatively. To this end, eight measures of SAL mutagenic potency were used. This study firmly establishes that the predictive relationship between mutagenic potency in SAL and rodent carcinogenicity is, at best, weak. When predicting qualitative carcinogenicity, only qualitative mutagenicity is useful; none of the quantitative measures of potency considered improves the carcinogenicity prediction. In fact, when qualitative mutagenicity is forced out of the model, the quantitative measures are still not predictive of carcinogenicity. When predicting quantitative carcinogenicity, several possible methods were considered for summarizing potency over all experiments; however, in all cases, the relationship between mutagenic potency predictors and quantitative carcinogenicity is very weak.

Mass human exposure to rabies in New Hampshire: exposures, treatment, and cost

OBJECTIVES

This study assessed the rabies exposure and treatment that at least 665 persons in Concord, NH, received as a result of one proven rabid pet-store kitten in October 1994.

METHODS

All treatment recipients were interviewed by person or phone.

RESULTS

The median age of the treatment recipients was 14 years; 58% were female. The most common exposures were low risk (e.g., picking up, petting, nuzzling, or being scratched by a potentially rabid kitten). Local reactions to vaccine or immune globulin were reported by 76.5% of recipients, while 48.8% reported at least one systemic reaction. Cost for the biologicals was estimated at more than $1.1 million.

CONCLUSIONS

Because of the inadequacy of pet store records, the inconsistent application of treatment guidelines, and other factors, many people received postexposure treatment as a result of contacts that were unlikely to transmit rabies. The rates of local and systemic adverse reactions experienced were consistent with previous reports.

Organelle-cytoskeletal interactions: actin mutations inhibit meiosis-dependent mitochondrial rearrangement in the budding yeast Saccharomyces cerevisiae

During early stages of meiosis I, yeast mitochondria fuse to form a single continuous thread. Thereafter, portions of the mitochondrial thread are equally distributed to daughter cells. Using time-lapse fluorescence microscopy and a membrane potential sensing dye, mitochondria are resolved as small particles at the cell periphery in pre-meiotic, living yeast. These organelles display low levels of movement. During meiosis I, we observed a threefold increase in mitochondrial motility. Mitochondrial movements were linear, occurred at a maximum velocity of 25 +/- 6.7 nm/s, and resulted in organelle collision and fusion to form elongated tubular structures. Mitochondria do not co-localize with microtubules. Destabilization of microtubules by nocodazole treatment has no significant effect on the rate and extent of thread formation. In contrast, yeast bearing temperature-sensitive mutations in the actin-encoding ACT1 gene (act1-3 and act1-133) exhibit abnormal mitochondrial aggregation, fragmentation, and enlargement as well as loss of mitochondrial motility. In act1-3 cells, mitochondrial defects and actin delocalization occur only at restrictive temperatures. The act1-133 mutation, which perturbs the myosin-binding site of actin without significantly affecting actin cytoskeletal structure in meiotic yeast, results in mitochondrial morphology and motility defects at restrictive and permissive temperatures. These studies support a role for the actin cytoskeleton in the control of mitochondrial position and movements in meiotic yeast.

Identifying anxiety disorders in adolescents hospitalized for alcohol abuse or dependence

In structured clinical interviews of 43 adolescents hospitalized for alcohol abuse or dependence, 17 subjects met criteria for an anxiety disorder, with social phobia (N = 9) and posttraumatic stress disorder (N = 7) most common. Of these 17 subjects, only four were identified in hospital records as having an anxiety disorder. In a comparison of 30 hospitalized adolescents with a matched control group of 30 adolescents from the community, the hospitalized adolescents had a higher rate of anxiety disorders, psychoactive substance use disorders, disruptive behavior disorders, and mood disorders.

Panic in otolaryngology patients presenting with dizziness or hearing loss

This study compared 50 patients presenting to an otolaryngology clinic with a complaint of dizziness and 50 patients presenting with hearing loss on questionnaire measures of panic, phobic avoidance, generalized anxiety, and depression. Clinical and laboratory evaluations of vestibular and audiological complaints were also completed. Twenty percent of the group with dizziness and none of the group with hearing loss reported symptoms that met DSM-III-R criteria for panic disorder. Patients with dizziness and peripheral vestibulopathy had more symptoms of phobic avoidance, generalized anxiety, and depression than patients with confirmed hearing loss.

Yeast mitochondria contain ATP-sensitive, reversible actin-binding activity

Sedimentation assays were used to demonstrate and characterize binding of isolated yeast mitochondria to phalloidin-stabilized yeast F-actin. These actin-mitochondrial interactions are ATP sensitive, saturable, reversible, and do not depend upon mitochondrial membrane potential. Protease digestion of mitochondrial outer membrane proteins or saturation of myosin-binding sites on F-actin with the S1 subfragment of skeletal myosin block binding. These observations indicate that a protein (or proteins) on the mitochondrial surface mediates ATP-sensitive, reversible binding of mitochondria to the lateral surface of microfilaments. Actin copurifies with mitochondria during subcellular fractionation and is released from the organelle upon treatment with ATP. Thus, actin-mitochondrial interactions resembling those observed in vitro may also exist in intact yeast cells. Finally, a yeast mutant bearing a temperature-sensitive mutation in the actin-encoding ACT1 gene (act1-3) displays temperature-dependent defects in transfer of mitochondria from mother cells to newly developed buds during yeast cell mitosis.

Targeted integration of transfected and infected adeno-associated virus vectors containing the neomycin resistance gene

Human adeno-associated virus (AAV) integrates specifically into a site (AAVS1) on chromosome 19q13.3-qter. We report that both transfected and infected AAV-vectors will target a foreign gene preferentially to AAVS1. Of 11 infected cell lines studied, nine (82%) showed integration of the neomycin resistance marker into AAVS1, which confirms the findings of previous investigations. We also show site-specific integration (nine out of 12 cell lines, 75%) following transfection of an AAV vector containing the neomycin gene. The ability of transfected AAV sequences to preferentially target and express selectable genes at a known site in the human genome extends the potential use of AAV as a vector in gene therapy.

GM1 ganglioside treatment partially reverses the nigrostriatal dopamine defect in the weaver mutant mouse

The weaver mutation in the mouse is a developmental disorder characterized by cerebellar atrophy as well as decreased numbers of substantia nigra dopaminergic neurons and a striatal dopamine loss. Since the nigrostriatal dopamine loss occurs postnatally, the present study was performed to determine whether early intervention with GM1 ganglioside could alter the extent of this dopamine loss. Weaver mice that received injections of GM1 ganglioside (30 mg/kg) daily, beginning at 7-10 days of age, had significantly higher striatal dopamine levels and significantly more tyrosine hydroxylase-positive substantia nigra pars compacta neurons than weaver mice that received only daily saline injections. These results show that GM1 treatment can alter at least some aspects of this inherited developmental disorder. If the weaver defect is related to a deprivation of trophic support for certain midbrain dopaminergic neurons, the presence of GM1 may be able to enhance the survival of these neurons.

Some comments on potency measures in mutagenicity research

In this article, the measurement of the potency of a chemical or mixture from its dose response in a particular assay is addressed. Attention is focused on data from the Ames Salmonella assay. Three measures of potency are explored and shown to be highly correlated. The presentation then discusses specific areas of research that might benefit from a study of potency.