[Progress in epidemiological characteristics and surveillance and early warning of dengue fever in China]

Dengue fever is an acute mosquito-borne infectious disease caused by dengue virus and widely spread worldwide. Many factors, such as pathogens, vector organisms, climate, and social environment, affect its transmission and prevalence. The local dengue fever epidemic caused by imported cases in China shows a trend of increasing epidemic latitude and more widespread epidemic areas. However, the traditional monitoring and early warning models of dengue fever mainly focus on researching a single factor and a single area. Establishing a multi-factor forecast and early warning system is urgent to strengthen the early warning capability for the dengue fever epidemic. This paper mainly discusses the epidemic characteristics, the influencing factors, and the surveillance and early warning models of dengue fever in China to provide a reference for the effective prevention and control of dengue fever in China.

[Association of health-related physical fitness with kidney function and lipid profile among faculty in a university]

Objective: To study the association of health-related physical fitness (HPF) with kidney function and blood lipid to provide a basis to prevent chronic diseases and making exercise prescriptions. Methods: This study was conducted in December 2019 with 299 faculty members of a university in Shaanxi, testing HPF indicators (muscle mass, body fat percentage, grip, sit-and-reach, vital capacity) , kidney function indicators (creatinine, uric acid, urea) , and blood lipid indicators[triglyceride (TG) , total cholesterol (TC) , high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) ]. Spearman correlation analysis and binary logistic regression were used to analyze the association between HPF with kidney function and blood lipid indicators. Results: In men, muscle mass and grip strength were positively correlated with uric acid, body fat percentage was positively correlated with TG, sit-and-reach and vital capacity were negatively correlated with TG (r(s)=0.266, 0.337, 0.300, -0.339, -0.239, P<0.05) . In women, body fat percentage was positively correlated with uric acid, TG, TC and LDL-C, negatively correlated with creatinine and HDL-C, grip strength was positively correlated with creatinine, sit-and-reach was positively correlated with HDL-C and negatively correlated with TG, vital capacity was negatively correlated with urea (r(s)=0.240, 0.349, 0.214, 0.249, -0.254, -0.209, 0.186, 0.207, -0.255, -0.154, P<0.05) . Logistic regression showed that high body fat percentage was risk factor for abnormal uric acid and dyslipidemia in female faculty members (OR=1.114, 95%CI:1.023-1.213; OR=1.116, 95%CI: 1.034-1.208; P<0.05) . And high body fat percentage was risk factor for dyslipidemia in male faculty members (OR=1.129, 95%CI: 1.017-1.252, P<0.05) . Conclusion: High body fat percentage is associated with dyslipidemia and uric acid abnormalities in university faculty. HPF fitness assessment may be important for the prevention of chronic diseases related to kidney function or lipids.

Maternal nutrient restriction alters endocrine pancreas development in fetal heifers

Maternal nutrient restriction during pregnancy alters fetal programming, which modifies the growth and health of the offspring in postnatal life. In cattle, nutrient restriction during pregnancy can be a result of environmental or economic factors, but little is known about how it alters the physiology of the fetus and affects future reproductive or growth efficiency. This study used female monozygotic twins, produced through in vitro fertilization and embryo splitting, to determine the effect of moderate maternal nutrient restriction on fetal development. Recipient Angus cross heifers pregnant with one twin were fed a diet meeting 100% National Research Council (NRC) total energy requirements (n = 4; control), whereas recipient heifers pregnant with the second twin were fed at 70% of NRC total energy requirements (n = 4; restricted) from gestational day (GD) 158 to GD 265 in Calan gate feeders. Recipient heifers were killed at GD 265. Change in maternal metabolic body weight was greater from zero in restricted heifers than controls (P < 0.05); restricted heifers lost weight during the nutrient restriction period. There was no difference in last rib back fat or rib eye area between groups (P > 0.10). There was no difference in fetal weight, uterine weight, or total placentome weight between groups (P > 0.10). The pancreas weight was reduced in restricted fetuses compared with control fetuses (P < 0.01), but there were no other differences in fetal organ weights (P > 0.10). Plasma insulin concentrations were reduced in restricted fetuses compared with controls (P < 0.01), but there was no effect of maternal diet on plasma glucose or glucagon concentrations in the fetus (P > 0.10). Histological analyses of the fetal pancreas revealed no differences in endocrine cell number or localization. Results indicate that a modest late gestation nutritional restriction impairs development of the fetal pancreas in the cow. Additional research will be needed to determine if these developmental changes lead to altered glucose and insulin homeostasis in the adult.

[Study on the relationship between family-related factors and obesity of children and adolescents aged 6-17 years]

Objective: To analyze the relationship between family-related factors and the status of overweight and obesity in children and adolescents aged 6-17 years in China. Methods: Data were collected from the China National Nutrition and Health Surveillance in 2010-2012 program. A sample of 6 343 subjects aged 6-17 years was selected, with matched weight, education levels, household income and other family related factors of their parents. Univariate analysis and multivariate logistic regression were used to explore the relationship between family factors and overweight and obesity in school-aged children and adolescents. Results: After adjusted for age, gender and region, results from the multivariate logistic regression showed that both the overweight and obesity of children and adolescents were associated with maternal BMI (OR=1.83, 95%CI: 1.63-2.05), paternal BMI (OR=1.74, 95%CI: 1.57-1.94), mother's educational level (OR=1.24, 95%CI: 1.12-1.37) and household income (OR=1.30, 95%CI: 1.15-1.46). Conclusion: Factors as overweight or obesity status of the parents, mother's educational level and household income were positively correlated with the prevalence of overweight and obesity in Chinese children and adolescents.

Pet-associated Campylobacteriosis: A persisting public health concern

Campylobacter is regarded as a leading cause of human bacterial gastroenteritis in the United States. We report on a case of laboratory-confirmed Campylobacter jejuni infection in the Commonwealth of Pennsylvania among members of a household living with a laboratory-confirmed but non-speciated Campylobacter-infected puppy. We describe an outbreak of likely dog-associated campylobacteriosis, the risk factors, potential routes of exposure and the clinical features in the exposed family members, which began shortly after exposure to the recently purchased dog. We also provide public health recommendations to prevent Campylobacter infections in veterinary care providers, pet owners and those planning to adopt pets in the future. Finally, this report underscores the importance of the One Health approach when public health responders, human and animal healthcare providers and clinical diagnostic laboratories are tasked with developing effective strategies when investigating, detecting and responding to zoonoses (diseases shared between animals and humans).

Early life history of three pelagic-spawning minnows Macrhybopsis spp. in the lower Missouri River

Life-history characteristics of age-0 sturgeon chub Macrhybopsis gelida, shoal chub Macrhybopsis hyostoma and sicklefin chub Macrhybopsis meeki were compared using several methods. All Macrhybopsis species consumed mostly midge pupae, but M. meeki had the most general diet (Levins' index, B = 0.22) compared with M. hyostoma (B = 0.02) and M. gelida (B = 0.09). Morisita's diet overlap index among species pairs ranged from 0.62 to 0.97 and was highest between M. hyostoma and M. gelida. Daily ages estimated from lapilli otoliths for each species ranged from 15 to 43 days for M. gelida, 19 to 44 for M. hyostoma and from 16 to 64 days for M. meeki. Mean growth rates ranged from 0.79 mm day(-1) for M. meeki to 1.39 mm day(-1) for M. gelida. Mortality estimates indicated high daily survivorship rates for M. meeki (0.985), but could not be estimated for the other two species. Hatch date histograms were congruent with the belief that M. hyostoma and M. gelida spawn periodically from June to September. Macrhybopsis meeki, however, appeared to respond to a specific spawning cue as hatch dates were unimodal with a peak in July. These results fill a gap in current knowledge of these imperilled species that can be used to guide management decisions.

Abstract P2-09-01: Patient reported outcomes of multiplex breast cancer susceptibility testing utilizing a tiered-binned counseling and informed consent model in BRCA1/2 negative patients

Background:The risks, benefits and utilities of multiplex panels for breast cancer susceptibility are unknown and new counseling and informed consent models are needed. We sought to obtain patient reported outcomes of multiplex testing in BRCA1/2 negative patients utilizing a novel, previously piloted tiered-binned counseling model for multiplex testing. Methods:BRCA1/2 negative participants completed pre(V1) and post-test counseling(V2) and surveys evaluating cognitive, affective and behavioral responses to a 25-gene multiplex testing panel. We used linear regressions with estimation by GEE where appropriate. Results:376 patients have been approached. To date, 124 participants(33%) have consented to the study, 21(6%) declined and 231(61%) are considering. Of 95 who have completed pre-test counseling(V1), 88(93%) elected to proceed with 25-gene panel testing and (81%) were classified as making an informed choice after tiered-binned counseling. 6/53(11%) participants received a positive result, including 1 mutation in MSH2 and 5 in moderate penetrance genes (2 ATM, 1 BARD1, 1 CHEK2, 1 PALB2). 22/53(42%) participants received a variant of unknown significance(VUS). General anxiety and perceived utility decreased significantly with pre-test counseling and after results (Table 1). Knowledge increased with pre-test counseling; cancer worry increased after receipt of multiplex results. Higher cancer worry was associated only with lower income (2.6 points/income category, p&lt;0.01). Those with a VUS had greater decreases in perceived utility compared to negative (p=0.01) or positive (p=0.003) results. To date, there are no other significant differences in knowledge, distress or uncertainty by test result. Medical management recommendations for the proband changed in 3/6 with a positive result. Cascade testing in the family was discussed as an option in 3/6 with a positive result. Conclusions:Many BRCA1/2-negative patients proceed with 25-gene cancer susceptibility testing if offered and most make informed choices utilizing a tiered-binned genetic counseling model. The tiered-binned counseling model is associated with increased knowledge, decreases in general anxiety and uncertainty after pre-test counseling and disclosure of results, but an increase in cancer worry after result disclosure. The clinical utility, long-term outcomes and differences in patient reported outcomes by test result remain unknown.

Table 1 Baseline, Mean(SD)After V1, Mean(SD)After V2, Mean(SD) N=75ˆ;N=49ˆˆN=75ˆ;N=49ˆˆN=49ˆˆGeneral Anxiety (range 0-21)6.4(3.9)*;6.9(3.9)**6.0(4.3)*;6.6(4.2)**5.8(4.5)**General Depression (range 0-212.8(2.9);3.1(3.2)3.0(3.5);3.1(3.6)3.0(3.7)State Anxiety (range 20-80)35.5(11.2);36.6(11.9)35.5(11.8);36.8(11.9)36.1(12.2)Cancer Worry (range 0-75)18.2(13.5);20.1(13.8)**16.7(12.5);17.2(11.9)**21.0(13.9)**Knowledge (range 17-82)65.7(5.0)**;66.5(5.0)**68.0(5.7)**;68.4(5.6)**67.3(4.9)**Uncertainty (range 0-15)5.8(3.9);6.2(4.3)5.6(3.7);5.4(3.2)5.6(3.5)Perceived Utility (range 24-120)75.2(14.0)*;75.9(14.0)**73.0(14.1)*;74.1(13.4)**68.4(16.9)***p≤0.05 **p≤0.01. ˆcompleted V1. ˆˆcompleted V1 & V2. To date, 53 have received results and 49 have completed post-disclosure surveys.

Citation Format: Bradbury AR, Patrick-Miller L, Egleston BE, Maxwell KN, Brandt A, Brower J, DiGiovanni L, Long JM, Powers J, Stopfer J, Nathanson KL, Domchek SM. Patient reported outcomes of multiplex breast cancer susceptibility testing utilizing a tiered-binned counseling and informed consent model in BRCA1/2 negative patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-09-01.

Human exposure to rabid free-ranging cats: a continuing public health concern in Pennsylvania

Rabid free-ranging cats have been a public health concern in Pennsylvania since raccoon variant rabies first was recognized in the state in the early 1980s. Over the last decade, between 1.5 and 2.5% of cats submitted to Pennsylvania's state laboratories for rabies testing have been positive. In this report, we describe the extent of rabies in free-ranging cats in Pennsylvania. We also present two examples of human exposure to rabid free-ranging cats that occurred in Pennsylvania during 2010-2011 and the public health actions taken to address rabies exposure in the humans and animals. We then describe the concerns surrounding the unvaccinated and free-ranging cat population in Pennsylvania and possible options in managing this public and animal health problem.

Current drug targets for modulating Alzheimer's amyloid precursor protein: role of specific micro-RNA species

Alzheimer's disease (AD) is the most common form of dementia in the United States and is increasing in prevalence every year throughout the world. Recent clinical trial failures highlight the need for further insights into the molecular events that underlie the neurobiology of AD. Pathological aberrations in AD are believed to result, in part, from excess accumulation of amyloid-beta peptide (Aβ), a product of Aβ precursor protein (APP). Targeting APP levels would then be expected to reduce Aβ production in all forms of AD. Therefore, clarifying the regulatory network that governs APP expression is likely to reveal molecular players that could serve as novel drug targets. This review highlights recent work demonstrating the involvement of microRNA (miRNA) in this regulatory network. MiRNA are small, non-coding RNA that interact with target mRNA at sites of imperfect complementarity and mediate translational inhibition or transcript destabilization. We first review the neurobiology of AD and describe current therapeutic strategies. We then review transcriptional and post-transcriptional mechanisms utilized by cells to control APP expression. We conclude by highlighting recent work, including our own, which suggests miRNA are integral components of this regulatory framework and potential targets for future AD therapeutics.

Autism, Alzheimer disease, and fragile X: APP, FMRP, and mGluR5 are molecular links

The present review highlights an association between autism, Alzheimer disease (AD), and fragile X syndrome (FXS). We propose a conceptual framework involving the amyloid-β peptide (Aβ), Aβ precursor protein (APP), and fragile X mental retardation protein (FMRP) based on experimental evidence. The anabolic (growth-promoting) effect of the secreted α form of the amyloid-β precursor protein (sAPPα) may contribute to the state of brain overgrowth implicated in autism and FXS. Our previous report demonstrated that higher plasma sAPPα levels associate with more severe symptoms of autism, including aggression. This molecular effect could contribute to intellectual disability due to repression of cell-cell adhesion, promotion of dense, long, thin dendritic spines, and the potential for disorganized brain structure as a result of disrupted neurogenesis and migration. At the molecular level, APP and FMRP are linked via the metabotropic glutamate receptor 5 (mGluR5). Specifically, mGluR5 activation releases FMRP repression of APP mRNA translation and stimulates sAPP secretion. The relatively lower sAPPα level in AD may contribute to AD symptoms that significantly contrast with those of FXS and autism. Low sAPPα and production of insoluble Aβ would favor a degenerative process, with the brain atrophy seen in AD. Treatment with mGluR antagonists may help repress APP mRNA translation and reduce secretion of sAPP in FXS and perhaps autism.

Plant/soil concentration ratios for paired field and garden crops, with emphasis on iodine and the role of soil adhesion

In the effort to predict the risks associated with contaminated soils, considerable reliance is placed on plant/soil concentration ratio (CR) values measured at sites other than the contaminated site. This inevitably results in the need to extrapolate among the many soil and plant types. There are few studies that compare CR among plant types that encompass both field and garden crops. Here, CRs for 40 elements were measured for 25 crops from farm and garden sites chosen so the grain crops were in close proximity to the gardens. Special emphasis was placed on iodine (I) because data for this element are sparse. For many elements, there were consistent trends among CRs for the various crop types, with leafy crops > root crops ≥ fruit crops ≈ seed crops. Exceptions included CR values for As, K, Se and Zn which were highest in the seed crops. The correlation of CRs from one plant type to another was evident only when there was a wide range in soil concentrations. In comparing CRs between crop types, it became apparent that the relationships differed for the rare earth elements (REE), which also had very low CR values. The CRs for root and leafy crops of REE converged to a minimum value. This was attributed to soil adhesion, despite the samples being washed, and the average soil adhesion for root crops was 500 mg soil kg⁻¹ dry plant and for leafy crops was 5 g kg⁻¹. Across elements, the log CR was negatively correlated with log Kd (the soil solid/liquid partition coefficient), as expected. Although, this correlation is expected, measures of correlation coefficients suitable for stochastic risk assessment are not frequently reported. The results suggest that r ≈ -0.7 would be appropriate for risk assessment.

Verification of radionuclide transfer factors to domestic-animal food products, using indigenous elements and with emphasis on iodine

Recent reviews have established benchmark values for transfer factors that describe radionuclide transfer from plants to animal food product such as milk, eggs and meat. They also illustrate the paucity of data for some elements and some food products. The present study quantified transfer data using indigenous elements measured in dairy, poultry and other livestock farms in Canada. Up to 62 elements are reported, with particular emphasis on iodine (I) because of the need to accurately assess the behaviour of (129)I from disposal of nuclear fuel waste. There was remarkable agreement with the literature values, and for many elements the present study involved many more observations than were previously available. Perhaps the most important observation was that product/substrate concentration ratios (CR) were quite consistent across species, whereas the traditional fractional transfer factors (TF, units of d kg(-1) or d L(-1)) necessarily vary with body mass (feed intake). This suggests that for long-term assessments, it may be advisable to change the models to use CR rather than TF.

Measured elemental transfer factors for boreal hunter/gatherer scenarios: fish, game and berries

The environmental assessment of long-term nuclear waste management requires data to estimate food chain transfers for radionuclides in various environmental settings. For key elements such as iodine (I) and chlorine (Cl), there is a paucity of transfer factor data, particularly outside of agricultural food chains. This study dealt with transfers of I, Cl and 28 other elements to foods that would be typical of boreal hunter/gatherer lifestyles, as well as being common foods for modern recreational and subsistence hunters. Food/substrate concentration ratios (CRs) and related transfer factors for eight species of widely distributed fish, whitetail deer (Odocoileus virginianus), Canada geese (Branta canadensis) and wild blueberries (Vaccinium myrtilloides) were measured and compared to the literature. Limited data were obtained for caribou (Rangifer tarandus), elk (Cervus elaphus) and moose (Alces americanus). Freshwater sediment Kd values and CRs for a ubiquitous freshwater macrophyte were also obtained. The CRs for I in fish were 29Lkg(-1) in edible muscle (fillets) of large-bodied species and 85Lkg(-1) for whole, small-bodied fish. The logCRs for fish and macrophytes were correlated across elements. For several elements, the Kds for sediments in deep water were approximately 4-fold higher than for littoral samples. The elemental transfers to wild animals for some elements were notably different than the literature indicates for domestic animals. It is argued that the transfer data obtained using indigenous elements from real environmental settings, as opposed to contaminant elements in experimental or impacted environments, are especially relevant to assessment of long-term impacts.

Reduced expression of the Sp4 gene in mice causes deficits in sensorimotor gating and memory associated with hippocampal vacuolization

HF-1B/SP4:, a member of the Sp1 family of transcription factors, is expressed restrictively in the developing nervous system and most abundantly in adult hippocampus in mice. Here, we report the generation of hypomorphic Sp4 allele mice, in which the Sp4 deficiency can be rescued by the expression of Cre recombinase. Vacuolization was detected in the hippocampal gray matter of the mutant Sp4-deficient mice. Expression analysis of Sp4 mutant hippocampi revealed an age-dependent decrease in neurotrophin-3 expression in the dentate granule cells. Hypomorphic Sp4 mutant mice displayed robust deficits in both sensorimotor gating and contextual memory. The restoration of Sp4 expression, via a Cre-dependent rescue strategy, completely rescued all the observed molecular, histological and behavioral abnormalities. Our studies thus reveal a novel Sp4 pathway that is essential for hippocampal integrity and modulates behavioral processes relevant to psychiatric disorders.

Expanded characterization of the social interaction abnormalities in mice lacking Dvl1

Dvl1 is one of three murine Dishevelled genes widely expressed in embryonic development and in the adult central nervous system. Dishevelled proteins are a necessary component of the Wnt and planar cell polarity developmental signaling pathways. We reported previously that mice deficient in Dvl1 exhibited abnormal social interaction and sensorimotor gating. To assess the validity of our earlier findings, we replicated the previous behavioral tests and included several new assays. The behaviors assessed included: social interaction, sensorimotor reflexes, motor activity, nociception, prepulse inhibition of acoustic startle (PPI) and learning and memory. Assessments with an explicit social component included: social dominance test, whisker trimming, nest building, home-cage huddling and ultrasonic vocalization rate analysis in pups. In addition, separate cohorts of wildtype and Dvl1-null mice were assessed for social recognition of a conspecific. Replicating the original report, Dvl1-null mice were impaired in several tasks containing an explicit social component. However, no impairment was observed in the social memory task. A previously observed deficit in PPI did not replicate in two institutions. In conclusion, we provide evidence that the social interaction phenotype of Dvl1-deficient mice has a strong genetic influence, but the sensorimotor gating deficit was subject to environmental influences. The specificity of observed social interaction deficits also suggests that lack of Dvl1 is associated with deficits in the recognition of social hierarchy and dominance.

Effects of estrogen and raloxifene on neuroglia number and morphology in the hippocampus of aged female mice

Hormone replacement therapy with the gonadal steroid estrogen or synthetic agents such as raloxifene, a selective estrogen receptor modulator, may affect cellular function in brains of postmenopausal women. In vitro studies suggest that 17beta estradiol and raloxifene can alter the microglial and astrocyte expression of immuno-neuronal modulators, such as cytokines, complement factors, chemokines, and other molecules involved in neuroinflammation and neurodegeneration. To directly test whether exogenous 17beta estradiol and raloxifene affect the number of glial cells in brain, C57BL/6NIA female mice aged 20-24 months received bilateral ovariectomy followed by s.c. placement of a 60-day release pellet containing 17beta estradiol (1.7 mg), raloxifene (10 mg), or placebo (cholesterol). After 60 days, numbers of microglia and astrocytes were quantified in dentate gyrus and CA1 regions of the hippocampal formation using immunocytochemistry and design-based stereology. The results show that long-term 17beta estradiol treatment in aged female mice significantly lowered the numbers of astrocytes and microglial cells in dentate gyrus and CA1 regions compared with placebo. After long-term treatment with raloxifene, a similar reduction was observed in numbers of astrocytes and microglial cells in the hippocampal formation. These findings indicate that estrogen and selective estrogen receptor modulators can influence glial-mediated inflammatory pathways and possibly protect against age- and disease-related neuropathology.

Identification of maze learning-associated genes in rat hippocampus by cDNA microarray

Long-term memory formation requires de novo RNA and protein synthesis. To assess gene-expression changes associated with learning and memory processes, we used cDNA microarray to analyze hippocampal gene expression in male Fischer-344 rats following training in a multiunit T-maze. Here, we report the identification of 28 clones (18 known genes and 10 ESTs) for which expression increased after the maze learning. Some of the known genes appear to be involved in Ca2+ signaling, Ras activation, kinase cascades, and extracellular matrix (ECM) function, which may regulate neural transmission, synaptic plasticity, and neurogenesis. The gene-expression profile presented here provides the groundwork for future, more focused research to elucidate the contribution of these genes in learning and memory processes.

Modeling human congenital disorder of glycosylation type IIa in the mouse: conservation of asparagine-linked glycan-dependent functions in mammalian physiology and insights into disease pathogenesis

The congenital disorders of glycosylation (CDGs) are recent additions to the repertoire of inherited human genetic diseases. Frequency of CDGs is unknown since most cases are believed to be misdiagnosed or unrecognized. With few patients identified and heterogeneity in disease signs noted, studies of animal models may provide increased understanding of pathogenic mechanisms. However, features of mammalian glycan biosynthesis and species-specific variations in glycan repertoires have cast doubt on whether animal models of human genetic defects in protein glycosylation will reproduce pathogenic events and disease signs. We have introduced a mutation into the mouse germline that recapitulates the glycan biosynthetic defect responsible for human CDG type IIa (CDG-IIa). Mice lacking the Mgat2 gene were deficient in GlcNAcT-II glycosyltransferase activity and complex N-glycans, resulting in severe gastrointestinal, hematologic, and osteogenic abnormalities. With use of a lectin-based diagnostic screen for CDG-IIa, we found that all Mgat2-null mice died in early postnatal development. However, crossing the Mgat2 mutation into a distinct genetic background resulted in a low frequency of survivors. Mice deficient in complex N-glycans exhibited most CDG-IIa disease signs; however, some signs were unique to the aged mouse or are prognostic in human CDG-IIa. Unexpectedly, analyses of N-glycan structures in Mgat2-null mice revealed a novel oligosaccharide branch on the "bisecting" N-acetylglucosamine. These genetic, biochemical, and physiologic studies indicate conserved functions for N-glycan branches produced in the Golgi apparatus among two mammalian species and suggest possible therapeutic approaches to GlcNAcT-II deficiency. Our findings indicate that human genetic disease due to aberrant protein glycosylation can be modeled in the mouse to gain insights into N-glycan-dependent physiology and the pathogenesis of CDG-IIa.

Structural brain aging in inbred mice: potential for genetic linkage

To identify genetic factors involved in brain aging, we have initiated studies assessing behavioral and structural changes with aging among inbred mouse strains. Cognitive performance of C57BL/6J mice is largely maintained with aging, and stereological analysis revealed no significant age-related change in neuron number, synaptic bouton number or glial number in the hippocampus. Moreover, no change in cortical neuron number and cholinergic basal forebrain neuron number has been found in this strain. 129Sv/J mice have more pronounced age-related cognitive deficits, although hippocampal and basal cholinergic forebrain neuron number also appear unchanged with aging. Differences in neurogenesis and neuron vulnerability in the adult CNS of C57BL/6, 129/Sv and other inbred strains have been reported, which in turn may have important consequences for brain aging. Age-related lesions, such as thalamic eosinophilic inclusions and hippocampal clusters of polyglucosan bodies also vary greatly among inbred strains although the functional significance of these lesions is not clear. The continued assessment of such age-related structural and behavioral changes among inbred mouse strains offers the potential to identify genes that control age-related changes in brain structure and function.

Dietary restriction increases the number of newly generated neural cells, and induces BDNF expression, in the dentate gyrus of rats

The adult brain contains neural stem cells that are capable of proliferating, differentiating into neurons or glia, and then either surviving or dying. This process of neural-cell production (neurogenesis) in the dentate gyrus of the hippocampus is responsive to brain injury, and both mental and physical activity. We now report that neurogenesis in the dentate gyrus can also be modified by diet. Previous studies have shown that dietary restriction (DR) can suppress age-related deficits in learning and memory, and can increase resistance of neurons to degeneration in experimental models of neurodegenerative disorders. We found that maintenance of adult rats on a DR regimen results in a significant increase in the numbers of newly produced neural cells in the dentate gyrus of the hippocampus, as determined by stereologic analysis of cells labeled with the DNA precursor analog bromodeoxyuridine. The increase in neurogenesis in rats maintained on DR appears to result from decreased death of newly produced cells, rather than from increased cell proliferation. We further show that the expression of brain-derived neurotrophic factor, a trophic factor recently associated with neurogenesis, is increased in hippocampal cells of rats maintained on DR. Our data are the first evidence that diet can affect the process of neurogenesis, as well as the first evidence that diet can affect neurotrophic factor production. These findings provide insight into the mechanisms whereby diet impacts on brain plasticity, aging and neurodegenerative disorders.

What counts in brain aging? Design-based stereological analysis of cell number

The advent and implementation of new design-based stereological techniques allows the quantification of cell number without the assumptions required when obtaining areal densities. These new techniques are rapidly becoming the standard for quantifying cell number, particularly in aging studies. Recently, studies using stereological techniques have failed to confirm earlier findings regarding age-associated neural loss. This newly emerging view of retained cell number during aging is having a major impact on biogerontology, prompting revaluation of long-standing hypotheses of age-related cell loss as causal for age-related impairments in brain functioning. Rather than focus on neuronal loss as the end-result of a negative cascade of neuronal injury, research has begun to consider that age-related behavioral declines may reflect neuronal dysfunction (e.g., synaptic or receptor loss, signal transduction deficits) instead of neuronal death. Here we discuss design-based stereology in the context of age-related change in brain cell number and its impact on consideration of structural change in brain aging. Emergence of this method of morphometrics, however, can have relevance to many areas of gerontological research.

Age-related psychomotor and spatial learning deficits in 129/SvJ mice

The 129 mouse strain has been widely used to construct mutations that model behavioral aging in humans. The current study found significant age-related declines in both psychomotor and swim maze performance of 5-, 17-, and 27-month-old 129/SvJ mice. However, the age differences in swim maze acquisition were inconsistent with poor performance in the probe trial which assesses spatial memory. This inconsistency may result from the high degree of genetic polymorphisms and age-related visual pathology which afflicts this mouse strain. Therefore, we concluded that 129/SvJ mice present a problematic model of mammalian cognitive aging and involve a risk for behavioral contamination in studies involving mutant mice derived from this strain.

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28-31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.

Effects of hippocampal and parietal cortex lesions on memory for egocentric distance and spatial location information in rats

To assess the working memory system for egocentric distance and place information, delayed matching-to-sample (DMTS) go/no-go tasks were run for each rat. To assess the reference memory system, and to serve as a control for nonmemory deficits, successive discrimination go/no-go tasks were then conducted using the same rats. Rats with hippocampal, but not parietal cortex, lesions were impaired relative to controls in the working memory (DMTS) task for both egocentric distance and place information, although the deficit observed in the working memory task for egocentric distance information by rats with hippocampal lesions was mild. Neither hippocampal nor parietal cortex lesioned rats were impaired relative to controls in the reference memory (successive discrimination) task for either cue. The hippocampus appears to be involved in working memory for egocentric distance and in spatial location information, whereas the parietal cortex is not.

Stereological estimation of total microglia number in mouse hippocampus

Microglia are brain cells of considerable interest because of their role in CNS inflammatory responses and strong association with neuritic plaques in Alzheimer's disease (AD). In the present study, immunocytochemistry was combined with unbiased stereology to estimate the mean total number of microglia in dentate gyrus and CA1 regions of the mouse hippocampus. Systematic-uniform-random (SUR) sections were cut through the hippocampal formation of male C57BL/6J mice (n = 7, 4-5 months) and immunostained with Mac-1, an antibody to the complement subunit 3 receptor (CR3). The total number of Mac-1 immunopositive cells was determined using the optical fractionator method. The mean total number of microglia in the mouse dentate gyrus was estimated to be 20,300 (CV = 0.21) with a mean coefficient of error (CE) = 0.09. The mean total number of microglia in the mouse CA1 was estimated to be 43,200 (CV = 0.24) with a CE = 0.11. Comparison of total number estimates, derived from fraction- or volume-based methods, supported stereological theory regarding the equivalence of the two techniques. The time required to determine total microglia number in both hippocampal sub-regions was approximately 6 h per mouse from stained sections. The combination of immunocytochemistry and stereology provides a reliable means to assess microglia number that can easily be adopted for studies of transgenic and lesion-based models of aging and neurodegenerative diseases.

Stereological analysis of astrocyte and microglia in aging mouse hippocampus

Recent evidence suggests neuroglia-mediated inflammatory mechanisms may stimulate neurodegenerative processes in mammalian brain during aging. To test the hypothesis that the number of microglia and astrocytes increase in the hippocampus during normal aging, unbiased stereological techniques were used to estimate total cell number in hippocampal subregions (CA1, dentate gyrus and hilus) of male C57BL/6J mice of different ages: 4-5 months, 13-14 months and 27-28 months. Immunocytochemical visualization for microglia and astrocytes were via Mac-1 and GFAP antibody, respectively. Estimates of total microglia and astrocyte number were assessed using the optical fractionator. No statistically significant age differences were found in the numbers of microglia or astrocytes in the hippocampal regions sampled. These findings suggest that age-related increases in the total numbers of hippocampal microglia and astrocytes is not causal for observed age-related increases in cytokine response.

Effects of hippocampal and parietal cortex lesions on memory for egocentric distance and spatial location information in rats

To assess the working memory system for egocentric distance and place information, delayed matching-to-sample (DMTS) go/no-go tasks were run for each rat. To assess the reference memory system, and to serve as a control for nonmemory deficits, successive discrimination go/no-go tasks were then conducted using the same rats. Rats with hippocampal, but not parietal cortex, lesions were impaired relative to controls in the working memory (DMTS) task for both egocentric distance and place information, although the deficit observed in the working memory task for egocentric distance information by rats with hippocampal lesions was mild. Neither hippocampal nor parietal cortex lesioned rats were impaired relative to controls in the reference memory (successive discrimination) task for either cue. The hippocampus appears to be involved in working memory for egocentric distance and in spatial location information, whereas the parietal cortex is not.

Brief communication: a software solution for reducing startle eyeblink responses

We examined the viability of a software-based spectral method for reducing acoustic startle eyeblink responses. Fifteen young adults were presented with a 95 dB burst of white noise for 50 ms while they viewed slides that varied in affective valence. The startle EMG responses were analyzed using a discrete Fourier transform software-based spectral method. A significant linear trend was found between slide valence and startle amplitude, replicating previous work. Subjects' startle responses became more augmented as the content of the slides became more unpleasant. The advantages of software-based solutions for reducing startle EMG responses are discussed.

Medication compliance and the older hemodialysis patient

OBJECTIVE

The purpose of this study was to identify relationships between demographic factors, psychosocial characteristics, and medication compliance rates in older patients receiving hemodialysis and to determine the effectiveness of a teaching program on medication-taking behavior.

DESIGN

A descriptive correlational study design was used.

SAMPLE/SETTING

A total of 26 patients, age 65 and over, undergoing hemodialysis at an inner city outpatient dialysis clinic met sample criteria.

METHODS

The instrument included a demographic data form, the Iowa Self-Assessment Inventory (ISAI) to measure psychosocial variables, and a form to collect data to calculate medication compliance rates.

RESULTS

All participants were African-American. Mean age was 70. Sample attrition was high. Scores were below the norm for most ISAI psychosocial factors, medication compliance rates were low, and the teaching intervention did not affect compliance rates.

CONCLUSION

Medication compliance in this older dialysis patient population was problematic, and further research in this area is essential.

Optimisation of the enantiomeric separation of 12 2-aminotetralin analogues using Chiral AGP high-performance liquid chromatography by simultaneous factorial design

A method for the simultaneous optimisation of mobile phase composition for the resolution of pairs of enantiomers of 12 2-aminotetralin analogues is presented. The selectivity necessary to discriminate between 12 analytes was obtained by using mass selective detection. The ability to examine more than a few analytes at a time extends the otherwise limited applicability of a factorial design strategy to the rapid development of chiral assays.

The effects of dorsal versus ventral hippocampal, total hippocampal, and parietal cortex lesions on memory for allocentric distance in rats

To test for the contribution of the parietal cortex and hippocampus to memory for allocentric spatial cues, the authors trained rats on a go/no-go task that required the rat to remember the distance between two visual cues. Total hippocampal lesions impaired working-memory representation for allocentric distance, whereas parietal cortex lesions resulted in only a transient impairment. In a second experiment, neither hippocampal nor parietal cortex lesions impaired allocentric distance discrimination. A third experiment showed that both the dorsal and ventral areas of the hippocampal formation must be destroyed to impair working memory for allocentric distance information. There appears to be a dissociation between the hippocampus and parietal cortex in mediating memory for allocentric distance information.

The effects of dorsal versus ventral hippocampal, total hippocampal, and parietal cortex lesions on memory for allocentric distance in rats

To test for the contribution of the parietal cortex and hippocampus to memory for allocentric spatial cues, the authors trained rats on a go/no-go task that required the rat to remember the distance between two visual cues. Total hippocampal lesions impaired working-memory representation for allocentric distance, whereas parietal cortex lesions resulted in only a transient impairment. In a second experiment, neither hippocampal nor parietal cortex lesions impaired allocentric distance discrimination. A third experiment showed that both the dorsal and ventral areas of the hippocampal formation must be destroyed to impair working memory for allocentric distance information. There appears to be a dissociation between the hippocampus and parietal cortex in mediating memory for allocentric distance information.

The Maine Lumbar Spine Study, Part II. 1-year outcomes of surgical and nonsurgical management of sciatica

STUDY DESIGN

The Maine Lumbar Spine Study is a prospective cohort study of patients recruited from the practices of orthopedic surgeons, neurosurgeons, and occupational medicine physicians throughout Maine.

OBJECTIVE

To assess 1-year outcomes of patients with sciatica believed to be due to a herniated lumbar disc treated surgically or nonsurgically.

SUMMARY OF BACKGROUND DATA

Lumbar spine surgery rates vary by geographic region and may reflect uncertainty about optimal clinical use.

METHODS

Eligible consenting patients participated in a baseline interview performed by study personnel and then were mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, quality of life, and satisfaction with care.

RESULTS

Five hundred seven patients with sciatica, 275 treated surgically and 232 treated nonsurgically initially, were enrolled. Surgically treated patients, on average, had more severe symptoms and had more severe physical and imaging findings than nonsurgically treated patients at entry. Although few surgically treated patients had mild symptoms and few nonsurgically treated patients had severe symptoms, about half in each treatment group had symptoms that fell into a moderate category. At the 1-year evaluation, improvement in symptoms, functional status, and disability were found in both treatment groups. However, surgically treated patients reported significantly greater improvement. For the predominant symptom, either back or leg pain, 71% of surgically treated and 43% of nonsurgically treated patients reported definite improvement (P < 0.001). This effect was even greater after adjustment for differences between treatment groups at entry (relative odds of definite improvement, 4.3; P < 0.001). For patients with moderate symptoms and abnormal physical examination findings, surgical treatment also resulted in greater improvement than nonsurgical treatment. However, there was little difference in the employment or workers' compensation status of patients treated surgically versus nonsurgically (5% vs. 7% unemployed at 1-year follow-up if employed at entry [P = 0.68]; 46% vs. 55% receiving workers' compensation at 1-year follow-up if receiving it at entry [P = 0.30] for surgical and nonsurgical management, respectively). For patients with mild symptoms, the benefits of surgical and nonsurgical treatment were similar.

CONCLUSIONS

Although surgically treated patients were on average more symptomatic at entry, there was substantial overlap in symptoms between surgically treated and nonsurgically treated patients. Surgically treated patients with sciatica reported substantially greater improvement at 1-year follow-up. However, employment and compensation outcomes were similar between the two treatment groups, and surgery appeared to provide little advantage for the subset of patients with mild symptoms. These results should be interpreted cautiously, because surgical treatment was not assigned randomly. Long-term follow-up will determine if these differences persist.

The Maine Lumbar Spine Study, Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis

STUDY DESIGN

A prospective cohort study of patients with lumbar spinal stenosis recruited from the practices of orthopedic surgeons and neurosurgeons throughout Maine.

OBJECTIVE

To assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically.

SUMMARY OF BACKGROUND DATA

No randomized trials and few nonexperimental studies have compared surgical and nonsurgical treatment of patients with lumbar spinal stenosis. The authors' goal was to assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically.

METHODS

Eligible, consenting patients participated in baseline interviews and were then mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, and satisfaction with care.

RESULTS

One hundred forty-eight patients with lumbar spinal stenosis were enrolled, of whom 81 were treated surgically and 67 treated nonsurgically. On average, patients in the surgical group had more severe imaging findings and symptoms and worse functional status than patients in the nonsurgical group at entry. Few patients with mild symptoms were treated surgically, and few patients with severe symptoms were treated nonsurgically. However, of the patients with moderate symptoms, a similar percent were treated surgically or nonsurgically. One year after study entry, 28% of nonsurgically and 55% of surgically treated patients reported definite improvement in their predominant symptoms (P = 0.003). For patients with moderate symptoms, outcomes for surgically treated patients were also improved compared with those of nonsurgically treated patients. Surgical treatment remained a significant determinant of 1-year outcome, even after adjustment for differences between treatment groups at entry (P = 0.05). The maximal benefit of surgery was observed by the time of the first follow-up evaluation, which was at 3 months. Although few nonsurgically treated patients experienced a worsening of their condition, there was little improvement in symptoms and functional status compared with study entry.

CONCLUSIONS

At a 1-year evaluation of patient-reported outcomes, patients with severe lumbar spinal stenosis who were treated surgically had greater improvement than patients treated nonsurgically. Comparisons of outcomes by treatment received must be made cautiously because of differences in baseline characteristics. A determination of whether the outcomes observed persist requires long-term follow-up.

Bioelectrical impedance as a discriminator of pressure ulcer risk

In an effort to identify objective measures of tissue structure and function associated with pressure ulcer risk, bioelectrical impedance analysis (BIA) was measured in three progressively larger zones over the trochanter and coccyx in patients assessed at high risk for pressure ulcers (HR group) and age-matched normal controls (CONT group). Local BIA measures were significantly lower in the HR group for each individual site and zone (p < .01). Full-thickness tissue biopsies obtained from each measurement zone did not differ between groups. However, additional nutritional and metabolic parameters were significantly different (p < or = .05). These results suggest that local BIA may be useful in assessing pressure ulcer risk.

Prefrontal cortex and working memory for spatial response, spatial location, and visual object information in the rat

In the first experiment, rats were trained on a working memory task for a spatial response (right-left turn) information using a delayed matching-to-sample procedure. Following lesions of the medial prefrontal cortex (MPF), which includes anterior cingulate and medial precentral cortex, there was a profound working memory deficit even at the shortest delay. In the second experiment, rats were trained on a working memory task for spatial location information using a delayed matching-to-sample procedure. Following lesions of the MPF, there was only a mild working memory deficit, whereas following dorsal hippocampal lesions there was a profound working memory deficit even at the shortest delay. In the third experiment, rats were trained on a working memory task for visual object information using a delayed nonmatching-to-sample procedure. Following lesions of the MPF, there were no working memory deficits, whereas following lesions of the prelimbic and infralimbic cortex there was a profound working memory deficit even at the shortest delay. The results suggest that different neural subregions of the prefrontal cortex mediate working memory for specific attribute information.

Frontal activation asymmetry and social competence at four years of age

The pattern of frontal activation as measured by the ongoing electroencephalogram (EEG) may be a marker for individual differences in infant and adult disposition to respond with either positive or negative affect. We studied 48 4-year-old children who were first observed in same-sex quartets during free-play sessions, while making speeches, and during a ticket-sorting task. Social and interactive behaviors were coded from these sessions. Each child was subsequently seen 2 weeks later when EEG was recorded while the child attended to a visual stimulus. The pattern of EEG activation computed from the session was significantly related to the child's behavior in the quartet session. Children who displayed social competence (high degree of social initiations and positive affect) exhibited greater relative left frontal activation, while children who displayed social withdrawal (isolated, onlooking, and unoccupied behavior) during the play session exhibited greater relative right frontal activation. Differences among children in frontal asymmetry were a function of power in the left frontal region. These EEG/behavior findings suggest that resting frontal asymmetry may be a marker for certain temperamental dispositions.

Phencyclidine impairs temporal order memory for spatial locations in rats

The effects of phencyclidine (PCP), an NMDA antagonist, was assessed on a complex task that has been shown to be dependent on hippocampal function. This task required memory for the temporal order of spatial locations. Rats were given IP injections of saline or PCP (3-4 mg/kg) on a double alternation schedule. With PCP injections rats were severely impaired relative to saline injections. Furthermore, PCP was shown to have no effects on the ability of rats to discriminate three-dimensional objects (a task that is not dependent on hippocampal function). The present data, in conjunction with previous results, suggest that the involvement of NMDA receptors in the hippocampus might be a function of the complexity of the task.

Effect of aspirin use on death and recurrent myocardial infarction in current and former cigarette smokers. Program on the Surgical Control of the Hyperlipidemias Group

The purpose of this study was to examine the effects of aspirin use on mortality and morbidity rates in a subset of the control group of the Program on the Surgical Control of the Hyperlipidemias (POSCH) that was stratified by cigarette smoking status at the time of randomization. The clinical impact of aspirin intake in cigarette smokers and former cigarette smokers has not been well studied. POSCH was a randomized, controlled, clinical trial designed to ascertain the effects of lipid modification by the partial ileal bypass operation on clinical end-points and arteriographic changes in postmyocardial infarction subjects with hypercholesterolemia. Cohorts of cigarette smokers in the diet-control group were evaluated for overall and atherosclerotic coronary heart disease (ACHD) mortality rates and recurrent confirmed nonfatal myocardial infarction rates. In current cigarette smokers at baseline (n = 90) with a mean follow-up of 8.3 years, the overall mortality rate was 45.2% in patients with no aspirin use and 10.4% in patients who reported even infrequent aspirin use (relative risk = 4.3, 95% confidence interval (CI) = 2.4 to 10.6, p < 0.001). For ACHD mortality in this cohort, the relative risk was 17.1 (35.7% vs 2.1%, 95% CI = 1.4 to 125.0, p < 0.001); for the combined end-point of ACHD mortality and nonfatal myocardial infarction, the relative risk was 2.4 (40.5% vs 16.7%, 95% CI = 1.2 to 5.1, p = 0.018).(ABSTRACT TRUNCATED AT 250 WORDS)

The development and validation of a high performance liquid chromatography (HPLC)/tandem mass spectrometry assay for fenticonazole in human plasma and comparison with an HPLC-UV method

A method is described for the determination of fenticonazole in human female plasma. The method utilizes high performance liquid chromatography coupled to atmospheric pressure positive-ion chemical ionization triple quadrupole mass spectrometry. Multiple reaction monitoring is employed for selectivity and sensitivity which enables quantification over the range 0.5-20 ng mL-1 with acceptable precision and accuracy. A comparison is made with an existing HPLC-UV assay and the utility of the technology of combined liquid chromatography and tandem mass spectometry for subnanogram per mL assays is discussed.

Variable-interval probe test as a tool for repeated measurements of spatial memory in the water maze

Probe tests provide an important additional converging operation to identify the characteristics of cognitive processes being assessed by other behavioral measures. We introduce a new procedure using a variable-interval (VI) probe test to assess spatial memory in the water maze. Three groups of rats were trained in spatial discrimination with traditional platform trials. For the probe trials, 2 groups had no-platform (NP) probe trials in which the escape platform was unavailable for the entire trial. The 3rd group had variable interval (VI) probe trials, in which the escape platform was available only after a VI. The VI probe trial was a more sensitive measure of spatial memory than was the NP probe trial and was useful for repeated measurements of spatial memory, a characteristic not readily attainable with the NP probe trial.

Chronic treatment of aged mice with L-deprenyl produces marked striatal MAO-B inhibition but no beneficial effects on survival, motor performance, or nigral lipofuscin accumulation

Male C57BL/6J mice were provided I-deprenyl (at 0, 0.5 mg/kg or 1.0 mg/kg per day) in their drinking water beginning at 18 months of age. A battery of motor tests, including open-field, tightrope, rotorod, inclined screen, runwheel, and rotodrum tests, was administered before treatment and then 6 months later at 24 months of age. A subsample of mice was retested again at 27 months of age. An untreated group of 9-month-old mice served as young controls. Deprenyl treatment reduced striatal MAO-B activity by up to 60% after 6 months on treatment but had no significant effects on striatal catecholamine levels. No significant effects of deprenyl treatment were observed on body weight, fluid intake, or survival of the mice. Chronic deprenyl treatment also did not affect motor performance in any test, except rotodrum performance at 27 months of age, which was significantly better in the 1.0 mg/kg group treated group compared to controls. No age or deprenyl effects were observed with respect to cell counts in the substantia nigra. However, nigral cells containing lipofuscin increased with age, but this neurohistochemical parameter was also unaffected by deprenyl treatment.

Variable-interval probe test as a tool for repeated measurements of spatial memory in the water maze

Probe tests provide an important additional converging operation to identify the characteristics of cognitive processes being assessed by other behavioral measures. We introduce a new procedure using a variable-interval (VI) probe test to assess spatial memory in the water maze. Three groups of rats were trained in spatial discrimination with traditional platform trials. For the probe trials, 2 groups had no-platform (NP) probe trials in which the escape platform was unavailable for the entire trial. The 3rd group had variable interval (VI) probe trials, in which the escape platform was available only after a VI. The VI probe trial was a more sensitive measure of spatial memory than was the NP probe trial and was useful for repeated measurements of spatial memory, a characteristic not readily attainable with the NP probe trial.