Evaluation and comparison of risk-based and universal prenatal HCV screening programs in Alberta, Canada

BACKGROUND & AIMS

Canadian clinical practice guidelines currently recommend risk-based screening for HCV in pregnant individuals. However, no provinces or territories have ever compared the effectiveness of risk-based vs. universal screening for the prenatal diagnosis of HCV. We aimed to evaluate and compare HCV screening programs after implementing a universal population-level pilot program among prenatal patients in Alberta, Canada.

METHODS

The Alberta Prenatal Screening Program for Select Communicable Diseases was amended to include universal HCV antibody screening. Cohorts of pregnant individuals screened for HCV through risk-based or universal programs were generated over 1-year periods. HCV screening rates and prevalence were analyzed and compared between cohorts to evaluate the effectiveness of screening methods. Social and demographic risk factors for HCV-positive individuals were compared between screening cohorts to identify which populations may be overlooked with risk-based guidelines.

RESULTS

HCV antibody screening rates were 11.9% and 99.9% among pregnant individuals in the risk-based and universal cohorts, respectively. HCV prevalence among the cohorts was 0.07% and 0.11% (difference = 0.04%, p = 0.032), with an average of 21 additional HCV-positive pregnant individuals identified annually with universal screening. HCV-positive pregnant patients diagnosed through universal screening were more likely to engage in high-risk sexual behaviours/sex work compared to those diagnosed through risk-based screening (47.6% vs. 12.5%, respectively p = 0.035), suggesting that these high-risk cases are being missed by risk-based screening.

CONCLUSIONS

Universal HCV screening diagnoses significantly higher numbers of pregnant individuals infected with HCV compared to risk-based screening. Universal HCV screening or amending risk-based guidelines to incorporate more proxy variables for risk factors should be considered to improve prenatal HCV screening guidelines in Canada and help achieve HCV elimination in the next decade.

IMPACT AND IMPLICATIONS

HCV is a bloodborne pathogen that can cause severe liver disease and be vertically transmitted from a mother to her baby during pregnancy. Pregnant individuals in Alberta are currently only tested for HCV if they disclose engaging in activities that put them at risk of acquiring the infection (risk-based screening). Using a population-wide universal prenatal HCV screening program, our work shows that testing based on patient disclosed risk alone leads to the significant underdiagnosis of HCV in pregnant individuals and suggests individuals engaging in sex work or risky sexual behaviours are being overlooked by the current risk-based program. Our outcomes represent the first province-wide study to evaluate and compare prenatal HCV risk-based and universal screening programs in Canada and provide evidence to support the update of prenatal HCV screening policies across the country and in similar jurisdictions.

One high quality genome and two transcriptome datasets for new species of Mantamonas, a deep-branching eukaryote clade

Mantamonads were long considered to represent an "orphan" lineage in the tree of eukaryotes, likely branching near the most frequently assumed position for the root of eukaryotes. Recent phylogenomic analyses have placed them as part of the "CRuMs" supergroup, along with collodictyonids and rigifilids. This supergroup appears to branch at the base of Amorphea, making it of special importance for understanding the deep evolutionary history of eukaryotes. However, the lack of representative species and complete genomic data associated with them has hampered the investigation of their biology and evolution. Here, we isolated and described two new species of mantamonads, Mantamonas vickermani sp. nov. and Mantamonas sphyraenae sp. nov., for each of which we generated transcriptomic sequence data, as well as a high-quality genome for the latter. The estimated size of the M. sphyraenae genome is 25 Mb; our de novo assembly appears to be highly contiguous and complete with 9,416 predicted protein-coding genes. This near-chromosome-scale genome assembly is the first described for the CRuMs supergroup.

What's in a number? The value of titers as routine proof of immunity for medical students

OBJECTIVES

To assess the guideline concordance of medical school requirements for students' proof-of-immunity in the United States (US) and Canada.

METHODS

National guidelines for healthcare worker proof-of-immunity to measles, mumps, rubella, and varicella were compared to admission requirements for 62 US and 17 Canadian medical schools.

RESULTS

All surveyed schools accepted at least one recommended form of proof-of-immunity, however, contrary to national guidelines, 16% of surveyed US schools asked for a serologic titer, and only 73-79% US schools accepted vaccination as the sole proof-of-immunity.

CONCLUSIONS

The requirement of numerical, non-standardized serologic testing highlights an oversight in medical school admissions documentation. The requirement for quantitative values to demonstrate immunity is not practical from a laboratory standpoint, and is not needed to show individual immunity to these vaccine-preventable diseases. Until a more standardized process is adopted, laboratories will need to provide clear documentation and direction for quantitative titer requests.

Prevalence of syphilis coinfection in hepatitis C virus positive prenatal patients from Alberta during a pilot routine screening program

BACKGROUND: Alberta routinely screens pregnant patients for select communicable diseases. Hepatitis C virus (HCV) was added to the prenatal screening panel as part of a provincial pilot program in February 2020. This retrospective cross-sectional study aimed to characterize the prevalence of syphilis coinfections in prenatal patients infected with HCV following implementation of the pilot program.METHODS: Routine prenatal HCV and syphilis testing data were extracted from the Public Health Laboratory Information System over a 21-month period. HCV positivity was defined as HCV enzyme immunoassay (EIA) reactive with detected HCV ribonucleic acid (RNA) following molecular confirmation, and positive results were examined for syphilis coinfections. All patients reactive on a syphilis EIA and confirmatory Treponema pallidum particle agglutination (TPPA) or follow-up rapid plasma reagin (RPR) test were considered positive for syphilis. Descriptive statistics for coinfected patients were analyzed. RESULTS: Eighty-seven prenatal patients were identified to be positive for HCV. Of those, 19 (21.8%) were reactive on the syphilis EIA and 17 (19.5%) had confirmed infections with the TPPA or RPR tests. For HCV/syphilis coinfected patients, the majority resided in metropolitan regions (64.6%), were from the lowest income quintile neighbourhoods (47.1%) and had previously tested positive for HCV (82.4%) and syphilis (64.6%) at the public health laboratory. CONCLUSIONS: The prevalence of syphilis coinfections in prenatal patients infected with HCV is high in Alberta. HCV/syphilis coinfection prevalence should be further investigated in other jurisdictions and prenatal cohorts to better understand testing and treatment options for prevention of congenital transmission.

Comparison of SARS-CoV-2 spike antibody quantitative titer reporting using the World Health Organization International Standard Units by four commercial assays

The accurate measurement of serological response to SARS-CoV-2 vaccination is needed to correlate responses with effective protective immunity. The World Health Organization (WHO) has created an international standard to allow harmonization of immune response assessment to an arbitrary unit across different commercial assays; however, the accuracy of reporting of SARS-CoV-2 spike antibody titers in international standard units (BAU or IU/mL) from commercial assays is not well studied. Here, we report the performance comparison of four quantitative commercial assays testing for SARS-CoV-2 spike immunoglobins using the WHO's international standard. Sera, EDTA-plasma and heparinized plasma collected from individuals who are vaccine naïve or received BNT162b2 (Pfizer/BioNTech), mRNA-1273 (Moderna) or ChAdOx1-S (Oxford-AstraZeneca) were tested using Abbott Architect AdviseDx SARS-CoV-2 IgG II, DiaSorin LIAISON SARS-CoV-2 TrimericS IgG, Roche Elecsys Anti-SARS-CoV-2 S and GenScript cPass SARS-CoV-2 surrogate virus neutralization assays. The sensitivities ranged from 90% to 100%, and specificities from 88% to 100%. These four assays had excellent agreement (0.79–0.93) and correlation (0.87–0.97); however, Passing-Bablok regression analysis indicated that data generated by these assays were not comparable. Our data suggests that natural SARS-CoV-2 infection elicited a greater antibody response compared to vaccines, evident by a significantly higher neutralizing antibody titer in unvaccinated individuals who seroconverted.

HCV reflex testing: A single-sample, low-contamination method that improves the diagnostic efficiency of HCV testing among patients in Alberta, Canada

BACKGROUND

Hepatitis C virus (HCV) can be cured with antiviral treatments. Diagnosis normally requires two blood samples, one for serology screening and one for molecular confirmation. This multi-step process creates barriers in patient care and decreases testing for hard-to-reach populations. We used the cobas® 6800 to detect HCV RNA after antibody testing to investigate whether a single-sample reflex testing method is effective and efficient for diagnosing HCV-positive patients.

METHODS

HCV RNA-positive clinical samples (n = 152) were interchangeably loaded on the ARCHITECT i2000SR with negative samples (n = 152) in a checkerboard fashion, tested for HCV antibodies using fixed probes, and directly transferred to the cobas 6800 for molecular testing. Contamination rates, sensitivity, and specificity were determined by comparing Abbott m2000 and cobas 6800 viral loads. After implementing reflex testing, clinical data over a 6-month period were analyzed for diagnostic efficiency.

RESULTS

Contamination was present in 5 of 152 pairs (3.29%) after reflex testing. Sensitivity and specificity were 99.3% (95% CI 95.1% to 99.9%) and 100% (95% CI 97.5% to 100%), respectively, using the cobas 6800 assay after serotesting. Approximately 97% of clinical patients received a conclusive test result with the reflex-testing algorithm. For HCV-positive patients, mean diagnostic turnaround times were significantly lower using reflex testing versus the two-sample method (4 versus 39 days; p < 0.0001).

CONCLUSIONS

HCV reflex testing demonstrated low levels of contamination without compromising the integrity of the molecular assay. Implementation in clinical laboratories would increase the efficiency of diagnosis and decrease steps in the continuum of care for patients.

Epidemiological Characterization of Group B Streptococcus Infections in Alberta, Canada: An Update from 2014 to 2020

Group B Streptococcus (GBS) is a leading cause of invasive neonatal disease. Epidemiological surveillance of GBS is important to determine cumulative incidence, antimicrobial resistance rates, and maternal and neonatal disease prevention. In this study, we present an update on GBS epidemiology in Alberta, Canada, from 2014 to 2020. Over the 7-year period, 1,556 GBS isolates were submitted to the Alberta Public Health Laboratory for capsular polysaccharide (CPS) typing and antimicrobial susceptibility testing. We analyzed the distribution of CPS types in Alberta and found CPS types III (23.6%), Ia (16.0%), Ib (14.8%), II (13.3%), V (12.7%), IV (12.5%), and VI (2.38%) to be the most prevalent. Less than 1% each of CPS types VII, VIII, and IX were identified. In agreement with historical data, the presence of CPS type IV continued to rise across Alberta, particularly in cases of adult infection, where a 2-fold increase was observed. Cumulative incidences of GBS cases per 100,000 population and late-onset disease per 1,000 live births increased from 4.43 to 5.36 and 0.38 to 0.41, respectively, from 2014 to 2020. However, the incidence of early-onset disease decreased during the 7-year period from 0.2 to 0.07, suggestive of successful intrapartum chemoprophylaxis treatment programs. All GBS isolates were susceptible to penicillin and vancomycin. However, nonsusceptibility to erythromycin increased significantly, from 36.85% to 50.8%, from 2014 to 2020. Similarly, nonsusceptibility to clindamycin also increased significantly, from 21.0% to 45.8%. In comparison to historical data, the overall rates of GBS infection and antimicrobial resistance have increased and the predominant CPS types have changed. IMPORTANCE This work describes the epidemiology of invasive infections caused by the bacterium group B Streptococcus (GBS) in Alberta, Canada. We show that rates of invasive GBS disease have increased from 2014 to 2020 for both adult disease and late-onset disease in neonates, whereas the rate of early onset disease in neonates has decreased. We also show that the rate of resistance to erythromycin (an antibiotic used to treat GBS) has also increased in this time.

The reduced ARF regulatory system in Giardia intestinalis pre-dates the transition to parasitism in the lineage Fornicata

Giardia intestinalis is an enteric pathogen with an extremely modified membrane trafficking system, lacking canonical compartments such as the Golgi, endosomes, and intermediate vesicle carriers. By comparison the fornicate relatives of Giardia possess greater endomembrane system complexity. In eukaryotes, the ADP ribosylation factor (ARF) GTPase regulatory system proteins, which consist of the small GTPase ARF1, and its guanine exchange nucleotide factors (GEFs) and GTPase activating proteins (GAPs), coordinate temporal and directional trafficking of cargo vesicles by recognizing and interacting with heterotetrameric coat complexes at pre-Golgi and post-Golgi interfaces. To understand the evolution of this regulatory system across the fornicate lineage, we have performed comparative genomic and phylogenetic analyses of the ARF GTPases, and their regulatory GAPs and GEFs in fornicate genomes and transcriptomes. Prior to our analysis of the fornicates, we first establish that the ARF GAP sub-family ArfGAP with dual PH domains (ADAP) is sparsely distributed but present in at least four eukaryotic supergroups and thus was likely present in the Last Eukaryotic Common Ancestor (LECA). Next, our collective comparative genomic and phylogenetic investigations into the ARF regulatory proteins in fornicates identify a duplication of ARF1 GTPase yielding two paralogues of ARF1F proteins, ancestral to all fornicates and present in all examined isolates of Giardia. However, the ARF GEF and ARF GAP complement is reduced compared with the LECA. This investigation shows that the system was significantly streamlined prior to the fornicate ancestor but was not further reduced concurrent with a transition into a parasitic lifestyle.

Effects of health status on pressure-induced changes in phocid immune function and implications for dive ability

The ability of marine mammals to cope with environmental challenges is a key determining factor in strandings and successful release of rehabilitated animals. Dive behavior is related to foraging and thus survival. While dive adaptations have been well studied, it is unknown how the immune system responds to diving and whether health status impacts immune function during diving. This study investigated the functional response of ex situ immune cells from stranded phocids to in vitro increased pressure, over the course of rehabilitation. Blood samples were drawn from stranded harbor seals (Phoca vitulina), gray seals (Halichoerus grypus) and harp seals (Phoca groenlandica) at the time of admit to the Mystic Aquarium, Mystic, CT and again after rehabilitation (pre-release). Phagocytosis, lymphocyte proliferation and immune cell activation were measured in vitro, with and without exposure to 2000 psi (simulated dive depth of 1360 m). Plasma epinephrine and norepinephrine, and serum cortisol were measured in vivo. All hormone values decreased between admit and release conditions. Under admit or release conditions, pressure exposures resulted in significant changes in granulocyte and monocyte phagocytosis, granulocyte expression of CD11b and lymphocyte expression of the IL2 receptor (IL2R). Overall, pressure exposures resulted in decreased phagocytosis for admit conditions, but increased phagocytosis in release samples. Expression of leukocyte activation markers, CD11b and IL2R, increased and the response did not differ between admit and release samples. Specific hematological and serum chemistry values also changed significantly between admit and release and were significantly correlated with pressure-induced changes in immune function. Results suggest (1) dive duration affects the response of immune cells, (2) different white blood cell types respond differently to pressure and (3) response varies with animal health. This is the first study describing the relationship between diving, immune function and health status in phocids.

A pan-apicomplexan phosphoinositide-binding protein acts in malarial microneme exocytosis

Invasion of human red blood cells by the malaria parasite Plasmodium falciparum is an essential step in the development of the disease. Consequently, the molecular players involved in host cell invasion represent important targets for inhibitor design and vaccine development. The process of merozoite invasion is a succession of steps underlined by the sequential secretion of the organelles of the apical complex. However, little is known with regard to how their contents are exocytosed. Here, we identify a phosphoinositide-binding protein conserved in apicomplexan parasites and show that it is important for the attachment and subsequent invasion of the erythrocyte by the merozoite. Critically, removing the protein from its site of action by knock sideways preferentially prevents the secretion of certain types of micronemes. Our results therefore provide evidence for a role of phosphoinositide lipids in the malaria invasion process and provide further insight into the secretion of microneme organelle populations, which is potentially applicable to diverse apicomplexan parasites.

Human Health Risk from Consumption of Marine Fish Contaminated with DDT and Its Metabolites in Maputo Bay, Mozambique

Many countries with incidence of malaria, including those surrounding Maputo Bay, use dichloro-diphenyl-trichloroethane (DDT) to reduce mosquitoes. This study is the first to estimate the human health risk associated with consumption of marine fish from Maputo Bay contaminated with DDTs. The median for ∑DDTs was 3.8 ng/g ww (maximum 280.9 ng/g ww). The overall hazard ratio for samples was 1.5 at the 75th percentile concentration and 28.2 at the 95th percentile. These calculations show increased potential cancer risks due to contamination by DDTs, data which will help policy makers perform a risk-benefit analysis of DDT use in malaria control programs in the region.

Determinants of longitudinal health-related quality-of-life change in children with asthma from low-income families: a report from the PROMIS® Pediatric Asthma Study

BACKGROUND

How the longitudinal asthma control status and other socio-demographic factors influence the changes of health-related quality of life (HRQOL) among asthmatic children, especially from low-income families, has not been fully investigated.

OBJECTIVES

This study aimed to describe the trajectories of asthma-specific HRQOL over 15 months and examine the effect of asthma control status on HRQOL by taking socio-demographic factors into consideration.

METHODS

A total of 229 dyads of asthmatic children and their parents enroled in public insurance programs were recruited for assessing asthma control status and HRQOL over four time points of assessment. Asthma control status was measured using the Asthma Control and Communication Instrument, and asthma-specific HRQOL was assessed using the Patient-Reported Outcomes Measurement Information System's Pediatric Asthma Impact Scale. Latent growth models (LGMs) were applied to examine the trajectory of HRQOL and the factors contributing to the changes of HRQOL.

RESULTS

Unconditional LGM revealed that HRQOL was improved over time. Conditional LGM suggested that accounting for asthma control and participants' socio-demographic factors, the variation in the initial level of HRQOL was significant, yet the rate of change was not. Conditional LGM also revealed that poorly controlled asthma status was associated with poor HRQOL at each time point (P's < 0.05). Lower parental education was associated with lower baseline HRQOL (P < 0.05). Hispanic children had a larger increase in HRQOL over time (P < 0.01) than non-Hispanic White children.

CONCLUSIONS

Vulnerable socio-demographic characteristics and poorly controlled asthma status affect HRQOL in children. This finding encourages interventions to improve asthma control status and HRQOL in minority children.

Antimicrobial management of septic arthritis of the hand and wrist

PURPOSE

The optimal antimicrobial treatment for patients with hand or wrist septic arthritis is unknown. We report the treatment outcomes in patients with these infections.

METHODS

The medical records of 40 consecutive adult patients with hand or wrist septic arthritis treated at our institution from 2000 to 2008 were retrospectively reviewed. The primary outcome measure was treatment failure (histopathologic or microbiologic evidence of relapsed infection from the same joint or a contiguous anatomic area).

RESULTS

Involved joints were the wrist (n = 10, 25 %), metacarpal-phalangeal (n = 11, 27.5 %), proximal interphalangeal (n = 8, 20 %), distal interphalangeal (n = 10, 25 %), and thumb interphalangeal (n = 1, 2.5 %). Methicillin-sensitive (n = 15, 45 %) and -resistant (n = 7, 17.5 %) Staphylococcus aureus were the most common pathogens. Surgical therapies included open arthrotomy with debridement (n = 33, 82.5 %), arthroscopic debridement (n = 2, 5 %), and aspiration alone (n = 5, 12.5 %). Most patients (23/40, 58 %) received less than 1 week of parenteral antimicrobial therapy. Only two patients developed definite antimicrobial treatment failure, one of whom had an atypical mycobacterium infection. Patients with subacute to chronic infections were at high risk for finger amputation.

CONCLUSIONS

When combined with surgical debridement, relatively short courses of parenteral antimicrobial treatment (<1 week) supplemented with oral therapy for an additional 2-3 weeks is usually sufficient antimicrobial therapy for hand or wrist septic arthritis.

Temporal changes in blood variables during final maturation and senescence in male sockeye salmon Oncorhynchus nerka: reduced osmoregulatory ability can predict mortality

This study is the first to characterize temporal changes in blood chemistry of individuals from one population of male sockeye salmon Oncorhynchus nerka during the final 6 weeks of sexual maturation and senescence in the freshwater stage of their spawning migration. Fish that died before the start of their historic mean spawning period (c. 5 November) were characterized by a 20-40% decrease in plasma osmolality, chloride and sodium, probably representing a complete loss of osmoregulatory ability. As fish became moribund, they were further characterized by elevated levels of plasma cortisol, lactate and potassium. Regressions between time to death and plasma chloride (8 October: P < 0·001; 15 October: P < 0·001) indicate that plasma chloride was a strong predictor of longevity in O. nerka. That major plasma ion levels started to decline 2-10 days (mean of 6 days) before fish became moribund, and before other stress, metabolic or reproductive hormone variables started to change, suggests that a dysfunctional osmoregulatory system may initiate rapid senescence and influence other physiological changes (i.e. elevated stress and collapsed reproductive hormones) which occur as O. nerka die on spawning grounds.

Genetics and high cognitive ability

More is known about the genetics of general cognitive ability (g) than any other trait in psychology. Recent findings on the genetics of g include the following three examples: (1) heritability increases throughout the lifespan; (2) heritabilities of performance in cognitive tests are strongly correlated with the tests' loadings on a g factor; and (3) genetic effects on scholastic achievement largely overlap with genetic effects on cognitive ability. This body of genetic research addresses the aetiology of individual differences in the normal range. Much less is known about the genetics of the high end of the distribution. Finding heritability in the normal range of cognitive ability does not imply that high ability is also genetic in origin. However, the first twin study of high IQ children, which uses a new technique that analyses the average difference between extreme groups and the rest of the population, suggests that high IQ is as heritable as individual differences in the normal range. We are currently engaged in a molecular genetic study that attempts to identify specific genes that contribute to high ability.

Geoacoustic inversion of short range source data using a plane wave reflection coefficient approach

Acoustic time series data were collected in a shallow, hard bottom lake environment located in central Texas using both short range (2 m) implosive data, obtained with the source and a single hydrophone located near mid-depth in the waveguide, along with longer range implosive and explosive data from a near surface source to a bottom mounted hydrophone. Matched field inversions using simulated annealing were performed with a ray trace plus complex plane wave reflection coefficient forward propagation model that was validated in previous work. Isolating bottom interacting paths to perform the inversions is shown to be essential to reduce parameter uncertainties in the hard bottom environment and enables a systematic approach to the inversions which establishes the number of layers needed to represent the lake environment. Measured transmission loss data from a towed source were compared through a RMS error analysis to modeled transmission loss, constructed with the parameters from inversions of data from several source types, to further establish the validity of the inversion approach for this environment. Geoacoustic parameters obtained by inversions of short range, low frequency impulsive data are used to predict transmission loss at longer ranges and higher frequencies. The range dependence of the global minimum is discussed.

Attention resources and visible speech encoding in older and younger adults

Two experiments investigated adult age differences in the distribution of attention across a speaker's face during auditory-visual language processing. Dots were superimposed on the faces of speakers for 17-ms presentations, and participants reported the spatial locations of the dots. In Experiment 1, older adults showed relatively better detection performance at the mouth area than the eye area compared to younger adults. In Experiment 2, in the absence of audible language, both age groups did not differentially focus on the mouth area. The results are interpreted in light of Massaro's (1998, Perceiving talking faces: From speech perception to a behavioral principle. Cambridge, MA: MIT Press) theoretical framework for understanding auditory-visual speech perception. It is claimed that older adults' greater reliance on visible speech is due to a reallocation of resources away from the eyes and toward the mouth area of the face.

Broadband sound propagation in shallow water and geoacoustic inversion

Part of an experiment to test a measurement package in a shallow water region in the Gulf of Mexico was designed to gather broadband acoustic data suitable for inversion to estimate seabed geoacoustic parameters. Continuous wave tow acoustic signals at multiple frequencies and broadband impulsive source signals were recorded on a horizontal line array in a high-noise environment. Simulated annealing with a normal mode forward propagation model is utilized to invert for a geoacoustic representation of the seabed. Several inversions are made from different data samples of two light bulb implosions, the measured sound speed profiles at the HLA and at the positions of the light bulb deployments, and for two different cost functions. The different cost functions, measured sound speed profiles, and measured time series result in different inverted geoacoustic profiles from which transmission loss is generated for comparison with measurements. On the basis of physical consistency and from the comparison of the transmission loss and time series, a best estimate geoacoustic profile is selected and compared to those obtained from previously reported inversions. Uncertainties in the sound speed profile are shown to affect the uncertainties of the estimated seabed parameters.

Infants attend to second-order relational properties of faces

Two experiments investigated whether 7-month-old infants attend to the spatial distance measurements relating internal features of the human face. A visual preference paradigm was used, in which two versions of the same female face (one either lengthened or shortened, and one nonmodified) were presented simultaneously. In Experiment 1, infants looked longer at the nonmodified faces, which were determined to match the average distance relationships found in a sample of faces drawn from the same population. Longer looking times for modified faces were found in Experiment 2, in which the nonmodified faces were unusually long and the modified faces conformed to average distance measurements. It is proposed that infants' attention to the spatial relations of internal face features is an optimal tool for lifelong face recognition.

A genome-wide scan of 1842 DNA markers for allelic associations with general cognitive ability: a five-stage design using DNA pooling and extreme selected groups

All measures of cognitive processes correlate moderately at the phenotypic level and correlate substantially at the genetic level. General cognitive ability (g) refers to what diverse cognitive processes have in common. Our goal is to identify quantitative trait loci (QTLs) associated with high g compared with average g. In order to detect QTLs of small effect size, we used extreme selected samples and a five-stage design with nominal alpha levels that permit false positive results in early stages but remove false positives in later stages. As a first step toward a systematic genome scan for allelic association, we used DNA pooling to screen 1842 simple sequence repeat (SSR) markers approximately evenly spaced at 2 cM throughout the genome in a five-stage design: (1) case-control DNA pooling (101 cases with mean IQ of 136 and 101 controls with mean IQ of 100), (2) case-control DNA pooling (96 cases with IQ > 160 and 100 controls with mean IQ of 102), (3) individual genotyping of Stage 1 sample, (4) individual genotyping of Stage 2 sample, (5) transmission disequilibrium test (TDT; 196 parent-child trios for offspring with IQ > 160). The over all Type I error rate is 0.000125, which robustly protects against false positive results. The numbers of markers surviving each stage using a conservative allele-specific directional test were 108, 6, 4, 2, and 0, respectively, for the five stages. A genomic control test using DNA pooling suggested that the failure to replicate the positive case-control results in the TDT analysis was not due to ethnic stratification. Several markers that were close to significance at all stages are being investigated further. Relying on indirect association based on linkage disequilibrium between markers and QTLs means that 100,000 markers may be needed to exclude QTL associations. Because power drops off precipitously for indirect association approaches when a marker is not close to the QTL, we are not planning to genotype additional SSR markers. Instead we are using the same design to screen markers such as cSNPs and SNPs in regulatory regions that are likely to include functional polymorphisms in which the marker can be presumed to be the QTL.

Photochemically enhanced binding of small molecules to the tumor necrosis factor receptor-1 inhibits the binding of TNF-alpha

The binding of tumor necrosis factor alpha (TNF-alpha) to the type-1 TNF receptor (TNFRc1) plays an important role in inflammation. Despite the clinical success of biologics (antibodies, soluble receptors) for treating TNF-based autoimmune conditions, no potent small molecule antagonists have been developed. Our screening of chemical libraries revealed that N-alkyl 5-arylidene-2-thioxo-1,3-thiazolidin-4-ones were antagonists of this protein-protein interaction. After chemical optimization, we discovered IW927, which potently disrupted the binding of TNF-alpha to TNFRc1 (IC(50) = 50 nM) and also blocked TNF-stimulated phosphorylation of Ikappa-B in Ramos cells (IC(50) = 600 nM). This compound did not bind detectably to the related cytokine receptors TNFRc2 or CD40, and did not display any cytotoxicity at concentrations as high as 100 microM. Detailed evaluation of this and related molecules revealed that compounds in this class are "photochemically enhanced" inhibitors, in that they bind reversibly to the TNFRc1 with weak affinity (ca. 40-100 microM) and then covalently modify the receptor via a photochemical reaction. We obtained a crystal structure of IV703 (a close analog of IW927) bound to the TNFRc1. This structure clearly revealed that one of the aromatic rings of the inhibitor was covalently linked to the receptor through the main-chain nitrogen of Ala-62, a residue that has already been implicated in the binding of TNF-alpha to the TNFRc1. When combined with the fact that our inhibitors are reversible binders in light-excluded conditions, the results of the crystallography provide the basis for the rational design of nonphotoreactive inhibitors of the TNF-alpha-TNFRc1 interaction.

The salience of temporal cues in the developing structure of event knowledge

Two experiments used a novel method called Pathfinder to examine whether the salience of temporal cues embedded in event structure increases developmentally and whether people link event actions by simple adjacency relationships or embed them in an organized whole. A sequential format for eliciting knowledge was compared with a less structured format for dinner and bedtime events. Adults and their 8- and 10-year-old children demonstrated well-developed script organizations regardless of format, and organization improved across this age range. In Experiment 1, temporal cues were not a salient basis of comparison for 6-year-olds, but in Experiment 2 they could use temporal cues when instructed to do so. The results suggest that temporal salience increases between 6 and 10 years and that temporal knowledge of event actions is highly organized in this age range. Furthermore, children's event knowledge functions partly in the interaction between their developing event knowledge and the support provided by sequential constraints in the environment.

Context-dependent memory under stressful conditions: the case of skydiving

Two experiments examined the effect of differing levels of emotional arousal on learning and memory for words in matching and mismatching contexts. In Experiment 1, experienced skydivers learned words either in the air or on the ground and recalled them in the same context or in the other context. Experiment 2 replicated the stimuli and design of the first experiment except that participants were shown a skydiving video in lieu of skydiving. Recall was poor in air-learning conditions with actual skydiving, but when lists were learned on land, recall was higher in the matching context than in the mismatching context. In the skydiving video experiment, recall was higher in matching learn-recall contexts regardless of the situation in which learning occurred. We propose that under extremely emotionally arousing circumstances, environmental and/or mood cues are unlikely to become encoded or linked to newly acquired information and thus cannot serve as cues to retrieval. Results can be applied to understanding variations in context-dependent memory in occupations (e.g., police, military special operations, and Special Weapons and Tactics teams) in which the worker experiences considerable emotional stress while learning or recalling new information.

Presenilin-1 and -2 are molecular targets for gamma-secretase inhibitors

Presenilins are integral membrane protein involved in the production of amyloid beta-protein. Mutations of the presenilin-1 and -2 gene are associated with familial Alzheimer's disease and are thought to alter gamma-secretase cleavage of the beta-amyloid precursor protein, leading to increased production of longer and more amyloidogenic forms of A beta, the 4-kDa beta-peptide. Here, we show that radiolabeled gamma-secretase inhibitors bind to mammalian cell membranes, and a benzophenone analog specifically photocross-links three major membrane polypeptides. A positive correlation is observed among these compounds for inhibition of cellular A beta formation, inhibition of membrane binding and cross-linking. Immunological techniques establish N- and C-terminal fragments of presenilin-1 as specifically cross-linked polypeptides. Furthermore, binding of gamma-secretase inhibitors to embryonic membranes derived from presenilin-1 knockout embryos is reduced in a gene dose-dependent manner. In addition, C-terminal fragments of presenilin-2 are specifically cross-linked. Taken together, these results indicate that potent and selective gamma-secretase inhibitors block A beta formation by binding to presenilin-1 and -2.

Recent applications of polymer-supported reagents and scavengers in combinatorial, parallel, or multistep synthesis

There has been a wealth of recent reports concerning support-bound reagents and scavengers in the solution-phase synthesis of compound libraries and natural products. Important advances in 1999 include the continued development and use of novel reagents for heterocycle synthesis, the increased use of catch-and-release purification, and the development of increasingly sophisticated techniques to allow sequestering of many types of impurities from desired compounds. These techniques have all been combined to enable the complicated multistep synthesis of natural products and of libraries of novel drug-like molecules, without conventional purification.

A counterselection for the tryptophan pathway in yeast: 5-fluoroanthranilic acid resistance

The ability to counterselect, as well as to select for, a genetic marker has numerous applications in microbial genetics. Described here is the use of 5-fluoroanthranilic acid for the counterselection of TRP1, a commonly used genetic marker in the yeast Saccharomyces cerevisiae. Counterselection using 5-fluoroanthranilic acid involves antimetabolism by the enzymes of the tryptophan biosynthetic pathway, such that trp1, trp3, trp4 or trp5 strains, which lack enzymes required for the conversion of anthranilic acid to tryptophan, are resistant to 5-fluoroanthranilic acid. Commonly used genetic procedures, such as selection for loss of a chromosomally integrated plasmid, and a replica-plating method to rapidly assess genetic linkage in self-replicating shuttle vectors, can now be carried out using the TRP1 marker gene. In addition, novel tryptophan auxotrophs can be selected using 5-fluoroanthranilic acid.

Some limits on encoding visible speech and gestures using a dichotic shadowing task

Visible speech and gestures are two forms of available language information that can be used by listeners to help them understand the speaker's meaning. Previous research has shown that older adults are particularly dependent on visible speech, yet seem to profit less than younger adults from the speaker's gestures. To understand how visible speech and gestures are used when listening becomes difficult, the authors conducted an experiment with a dichotic shadowing task. The experiment examined how accurately participants could shadow the right- or left-ear input when instructed to attend selectively to a particular ear and whether performance benefited from visual input. The results indicate that older adults' shadowing performance was unaffected by visible speech and gestures. Younger adults did benefit by both visible speech and gestures. Thus, under extremely attention-demanding listening conditions, older adults are unable to use a compensatory mechanism for encoding visual language.

Parallel synthesis of prostaglandin E1 analogues

The first demonstration of the rapid parallel synthesis of diverse prostaglandin derivatives is reported. Upper (alpha-) side chain diversity was introduced to core 1 via the parallel Suzuki coupling of hydroborated alkenes. Conversion to the enones 3 and 9 was followed by the addition of the lower (omega-) side chains as higher-order cuprates 4. Upper side chains incorporating an N-acylsulfonamide protecting group were further transformed into prostaglandin amide analogues. Cleavage from support with HF/pyridine followed by scavenging provided 26 prostaglandin E1 analogues in high purity.

Neurotic butterflies in my stomach: the role of anxiety, anxiety sensitivity and depression in functional gastrointestinal disorders

This study examined the prevalence of functional gastrointestinal (FGI) disorders, and the association between FGI disorders and measures of affective distress, among a sample of 127 university students. Subjects completed a questionnaire battery including Research Diagnostic Questions for Functional Gastrointestinal Disorders, the Beck Anxiety Inventory, the Anxiety Sensitivity Index, the Beck Depression Inventory, and a medical utilization questionnaire. FGI disorders were diagnosed in 51.2% of the sample. Functional dyspepsia (22.8%), dyschezia (20.5%), functional heartburn (19.7%), functional chest pain (18.1%), and globus (12.6%) were the most frequently diagnosed disorders. Participants experiencing globus, functional dyspepsia, or functional heartburn showed significant differences in terms of anxiety, anxiety sensitivity, depression, and/or physician visits, when compared with participants without these disorders. Our results suggest that FGI disorders are strikingly prevalent among young adults, and specific FGI disorders are associated with affective distress. Implications of the observed association between psychological factors and FGI disorders are discussed.

DNA pooling and dense marker maps: a systematic search for genes for cognitive ability

Pooling DNA from subjects within a group and comparing the pooled DNA across groups for a dense map of DNA markers offers a solution to the conundrum that linkage is systematic but not powerful whereas allelic association is powerful but not systematic. We used DNA pooling to screen 66 markers on chromosome 22 in original and replication samples of children of high general cognitive ability (g) and controls of average g. Although none of these markers survived our three-stage screening design (original pooling, replication pooling, individual genotyping), the results of DNA pooling were largely confirmed by individual genotyping. We can therefore exclude associations of major effect size on chromosome 22 for g, a key variable for cognitive neuroscience research on learning and memory.

Developmental changes in the effect of dimensional salience on the discriminability of object relations

Two experiments explored three issues regarding the nature of perceptual development in 5- and 10-year-old children and adults: (a) the role of featural discriminability, (b) the facilitatory role of identity relations, and (c) the role of salience in a task context designed to minimize the likelihood of attention-switching between dimensions during perceptual processing. In Experiment 1, perceptual salience for size and achromatic color dimensions was determined for each participant based on their best-fitting triad classification task response pattern. These same persons participated in Experiment 2, which employed a speeded visual discrimination task. The primary finding was that preassessed salience significantly influenced the 5-year-olds' ability to discriminate between two objects, while salience did not affect 10-year-olds' or adults' response times. The results of both experiments support Odom & Cook's (1992) differential-sensitivity view of perceptual development, but these data contribute important information by showing that salience effects in perceptual processing occur even when the observer is selectively attending to a particular dimension, likely during early component processes prior to classification.

Dopamine markers and general cognitive ability

Because general cognitive ability (g) is among the most heritable behavioural traits, it is a reasonable target for a search for quantitative trait loci (QTLs). We used a selected-extremes design to test candidate genes for allelic association with g. Polymorphisms in four genes in the dopamine system (DRD2, DRD3, DRD4, DAT1) were genotyped for 51 high g children with IQ scores > 130 and for 51 average g control children. No significant allelic or genotypic differences were found between the high g and average g groups for these markers of the dopamine system, even though the selected-extremes design provides power to detect QTL associations that involve a relative risk of about 1.5.

What is so special about special education?

There is nothing special about special education. Educational methods have not changed significantly in at least 2,500 years. IQ tests were developed to identify those in need of special education, with the intention of developing appropriate educational methods. Effective special educational methods have yet to be developed. IQ tests are diagnostic but not prescriptive. Effective special educational methods will not be developed until (a) individual differences in student characteristics beyond IQ scores are recognized and understood and (b) educators focus on specific and realistic goals for outcome.

What is so special about special education?

There is nothing special about special education. Educational methods have not changed significantly in at least 2,500 years. IQ tests were developed to identify those in need of special education, with the intention of developing appropriate educational methods. Effective special educational methods have yet to be developed. IQ tests are diagnostic but not prescriptive. Effective special educational methods will not be developed until (a) individual differences in student characteristics beyond IQ scores are recognized and understood and (b) educators focus on specific and realistic goals for outcome.

No association between general cognitive ability and the A1 allele of the D2 dopamine receptor gene

Berman and Noble (1995) reported significantly reduced visuospatial performance in children with the TAQI A1 allele of the D2 dopamine receptor (DRD2) gene. Given that visuospatial performance loads highly on an unrotated principal component indexing general cognitive ability, we tested the association between DRD2 and WISC-R IQ comparing 51 high-IQ, 51 average-IQ, and 35 low-IQ children in the IQ Quantitative Trait Loci (QTL) Project. No statistically significant association between the TAQI A DRD2 alleles and IQ was found. Given that a statistically significant portion of genetic variance for specific cognitive abilities is independent of general cognitive ability, it is possible that the TAQI DRD2 association is specific to visuospatial performance and independent of general cognitive ability.

Cortical localization of human sustained attention: detection with functional MR using a visual vigilance paradigm

PURPOSE

Our goal was to determine whether functional MRI on a standard 1.5 T system can localize activation during a visual vigilance sustained attention task and whether this corresponds to results described in a PET investigation of a similar task.

METHOD

Sixteen volunteers were studied on a 1.5 T system using a gradient echo technique. A single axial section was oriented within a stereotaxic coordinate space, 40 mm superior to the anterior-posterior commissure line. Images with eyes closed were followed by images during subject concentration on a small dim spot. Motion correction and pixel-by-pixel statistical analysis were performed. Talairach grids were applied for summary statistical analysis and comparison to PET data, with analysis using a series of planned contrasts within a repeated measures analysis of variance.

RESULTS

Predominantly right-sided frontal and parietal activation was observed, with statistical significance across subjects in the right frontal lobe (F > or = 5.9, p < or = 0.041). Comparison with previously reported PET data yielded a very similar pattern of activation (F = 13.2; df = 1,8; p = 0.007).

CONCLUSION

Activation of the right middle frontal gyrus and right parietal lobe during visual vigilance is detectable across functional imaging modalities.

Information integration in cross-modal pattern recognition: an argument for acquired modularity

Three experiments addressed the issue of whether modularized operations (Fodor, 1983) in pattern recognition could be acquired. In Experiment 1, blind and sighted individuals were compared in the speech-tactile domain of pattern recognition. The results were inconsistent with the assumptions of the fuzzy logical model of perception (FLMP) (Oden and Massaro, 1978) and with the assumptions of modularized pattern recognition processes, but were consistent with the assumptions of 'penetrability' into non-modularized operations. Experiments 2 and 3 compared sighted individuals across speech-visual and speech-tactile domains, revealing fundamentally different patterns of performance that we argue demonstrate modularized and non-modularized FLMP operations in pattern recognition, respectively.

The independent prediction of general intelligence by elementary cognitive tasks: genetic and environmental influences

Current theories of intelligence have, in some cases, begun to include elementary cognitive tasks. Behavioral genetic studies of intelligence have not taken these theories into account. The current study includes 135 MZ and 128 DZ twin pairs from the Western Reserve Twin Project. The 11 WISC-R subtests as well as 6 elementary cognitive tasks were employed. Using a Schmid-Leiman (1957) transformation, analyses indicate a four-group factor model, supported by a second-order general factor at both phenotypic and biometric levels. Results indicate that the general factor, group factors, and specific residuals are necessary when examining additive genetic variance. Common environmental variance can be collapsed into a single general factor.

Encoding and memory for visible speech and gestures: a comparison between young and older adults

Two experiments explored whether older adults have developed a strategy of compensating for slower speeds of language processing and hearing loss by relying more on the visual modality. Experiment 1 examined the influence of visual articulatory movements of the face (visible speech) in auditory-visual syllable classification in young adults and older adults. Older adults showed a significantly greater influence of visible speech. Experiment 2 examined immediate recall in three spoken-language sentence conditions: speech alone, with visible speech, or with both visible speech and iconic gestures. Sentences also varied in meaningfulness and speech rate. In the old adult group, recall was better for sentences containing visible speech compared with the speech-alone sentences in the meaningful sentence condition. Old adults' recall showed no overall benefit of the presence of gestures. Young adults' recall on meaningful sentences was not higher for the visible speech compared with the speech-alone condition, whereas recall was significantly higher with the addition of iconic gestures. In the anomalous sentence condition, both young and old adults showed an advantage in recall by the presence of visible speech. The experiments provide converging evidence for old adults' greater reliance on visible speech while processing visual-spoken language.

Cryopreservation of human oocytes and fertilization by two techniques: in-vitro fertilization and intracytoplasmic sperm injection

Human oocyte cryopreservation results in poor survival and subsequent fertilization rates. It has been suggested that freeze-thaw-induced changes in the zona pellucida may impair sperm penetration or attachment. The aim of this study was to compare fertilization and cleavage rates in cryopreserved oocytes inseminated by conventional in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). A total of 220 oocytes, obtained from volunteers who had undergone ovarian stimulation, were cryopreserved using a slow freeze-rapid thaw protocol with 1.5 M propanediol as the cryoprotectant. Surviving oocytes (n = 74, 34.4%) were randomly allocated for fertilization by conventional IVF (group 1) or ICSI (group 2) using cryopreserved spermatozoa from a single donor of proven fertility. Fertilization was achieved in five (13.5%) of the oocytes in group 1 and 17 (45.9%) in group 2 (P < 0.005), with only one oocyte in group 1 exhibiting normal fertilization as opposed to 16 (43.2%) in group 2 (P < 0.001). Similarly, one oocyte fertilized by IVF cleaved, while all fertilized with ICSI cleaved (P < 0.001). We conclude that although the survival of oocytes is poor following cryopreservation, fertilization and cleavage rates can be enhanced significantly using ICSI. These data also suggest that the method of cryopreservation used in this study affected the zona pellucida, such that normal sperm attachment or penetration was impaired.

A twin study of competence and problem behavior in childhood and early adolescence

The Child Behavior Checklist (CBCL) was completed by parents of 181 pairs of same-sex twins ages 7-15 (mean age = 11.0 years). Correlations between scores on the CBCL scales for 99 pairs of monozygotic twins and 82 pairs of dizygotic twins indicated significant genetic influences that varied according to the specific area of competence and problem behavior. Model-fitting estimates derived from multiple regression analyses indicated significant genetic influence on competence in school and on all areas of problem behavior. In addition, significant shared environmental influence was detected for amount and quality of participation in activities, quality of social relationships, performance in school, anxiety/depression, and delinquent behaviour. Implications for future work on the mechanisms underlying these effects are discussed.

Current attitudes towards egg donation among men and women

Recent widespread concern has led to legislation in the UK preventing the use of fetal ovarian tissue for the treatment of infertile women. This questionnaire-based study aimed to assess the attitudes of both fertile and infertile men and women as well as egg donors and recipients towards the use of donated eggs for treatment, diagnosis and research. Fertile individuals were significantly less aware of egg donation but the majority in both the fertile and the infertile groups approved the use of eggs for research (89 and 95% of women and 88 and 92% of men respectively) and treatment (similar percentages). However, fetal sources of oocytes were acceptable to only 15% of women in the fertile, 21% in the infertile, 35% in the recipient and 19% in the donor groups. Cadaveric sources of oocytes were slightly more acceptable (28% fertile, 28% infertile, 50% recipient and 42% donors). Both these sources of oocytes were slightly more acceptable to men. Education had little influence on attitudes, although men and women of tertiary education level said they would be less likely to have gamete donation themselves. Thus there would appear to be widespread approval for the use of donor eggs in research and treatment but not if the source of eggs is fetal or cadaveric.

Encoding and memory for visible speech and gestures: a comparison between young and older adults

Two experiments explored whether older adults have developed a strategy of compensating for slower speeds of language processing and hearing loss by relying more on the visual modality. Experiment 1 examined the influence of visual articulatory movements of the face (visible speech) in auditory-visual syllable classification in young adults and older adults. Older adults showed a significantly greater influence of visible speech. Experiment 2 examined immediate recall in three spoken-language sentence conditions: speech alone, with visible speech, or with both visible speech and iconic gestures. Sentences also varied in meaningfulness and speech rate. In the old adult group, recall was better for sentences containing visible speech compared with the speech-alone sentences in the meaningful sentence condition. Old adults' recall showed no overall benefit of the presence of gestures. Young adults' recall on meaningful sentences was not higher for the visible speech compared with the speech-alone condition, whereas recall was significantly higher with the addition of iconic gestures. In the anomalous sentence condition, both young and old adults showed an advantage in recall by the presence of visible speech. The experiments provide converging evidence for old adults' greater reliance on visible speech while processing visual-spoken language.

The genetic and environmental variance underlying elementary cognitive tasks

Although previous studies have examined the genetic and environmental influences upon general intelligence and specific cognitive abilities in school-age children, few studies have examined elementary cognitive tasks in this population. The current study included 149 MZ and 138 same-sex DZ twin pairs who participated in the Western Reserve Twin Project. Thirty measures from the Cognitive Abilities Test (CAT; Detterman, 1986) were studied. Results indicate that (1) these measures are reliable indicators of general intelligence in children and (2) the structure of genetic and environmental influences varies across measures. These results not only indicate that elementary cognitive tasks display heterogeneous genetic and environmental effects, but also may demonstrate that individual differences in biologically based processes are not necessarily due to genetic variance.

A comparison of the effects of different biopsy strategies on the post-thaw survival of 8-cell-stage mouse embryos: implications for preimplantation diagnosis

The aim of this study was to investigate the effects of two different biopsy strategies, zona slitting and zona piercing, on the post-thaw survival and subsequent in-vitro development of 8-cell mouse embryos. From control experiments it was determined that neither biopsy by zona slitting nor zona piercing adversely affected embryo development in vitro, as similar rates of blastocyst formation and hatching were found between biopsied and zona-intact embryos; there was, however, a trend towards a lower rate of blastocyst hatching in embryos biopsied by zona piercing (78.3% compared with 91.9% of zona-intact embryos). When biopsy was followed by cryopreservation a different picture was seen: similar rates of freeze-thaw survival were found for zona-slit, zona-pierced and zona-intact embryos (84.2, 88.5 and 87.2% respectively), but this was superseded by a significant (P < 0.05) reduction in the blastocyst formation rates (61.4% zona-slit and 63.9% zona-pierced versus 78.7% zona-intact) and hatching rates (51% zona-slit and 52.5% zona-pierced versus 72.3% zona-intact) of the biopsied embryos. When the effects of zona slitting and piercing were considered in isolation, i.e. without performing biopsy, it was found that the larger holes produced by zona slitting rendered embryos more susceptible to freeze-thaw damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Dimensional strategies dominate perceptual classification

The nature of perceptual classification was investigated in children ranging between 4 and 10 years, and in young adults. Triad classification task responses were categorized as consistent or inconsistent with several classification rules, including: overall-similarity, size-dimensional, brightness-dimensional, pure identity, and all combinations of a switch from one rule to another midway through the experiment. The rule with the highest proportion of responses consistent with it reflected each person's best-fitting rule pattern. The higher this value, the higher the assumed consistency of rule usage. Data from the majority of individuals in every age group conformed best to one of the three dimensional rules. In addition, the consistency values for individuals' best-fitting rule became significantly higher as age increased. It is concluded that most children have a tendency to attend selectively to one stimulus dimension when making perceptual classification judgments. The developmental trend in perceptual classification does not appear to be a holistic-to-analytic shift; instead, it is a trend toward greater consistency in following a given classification rule.

Intracellularly recorded response of rat striatal neurons in vitro to fenoldopam and SKF 38393 following lesions of midbrain dopamine cells

The effect of long-term (6-19 weeks) 6-hydroxydopamine-induced (6-OHDA) lesions of midbrain dopamine cells on dopamine D1-like agonist-induced changes in the excitability of rat striatal neurons was investigated in vitro using tissue slices and intracellular recording techniques. Fenoldopam and (+/-)-SKF 38393 predominantly decreased excitability in control preparations including striatal neurons located contralateral to 6-OHDA injection sites and neurons obtained from rats receiving sham injections or no treatment. Fenoldopam also inhibited neurons ipsilateral to lesions of midbrain dopamine cells. (+/-)-SKF 38393, unlike fenoldopam, produced predominantly increases in the excitability of ipsilateral striatal neurons. Superfusion of the D1 receptor antagonist, SCH 23390, blocked fenoldopam-induced decreases in excitability but not the (+/-)-SKF 38393-induced excitation of neurons ipsilateral to the lesion. Sequential application of fenoldopam and quinpirole, a D2/D3 receptor agonist, produced responses to both drugs in a majority of neurons. The results demonstrate that inhibitory responses to fenoldopam are mediated by D1 receptors, while excitatory effects of (+/-)-SKF 38393 in the striatum ipsilateral to the lesion are apparently not dependent on D1 receptor activation. These findings also suggest that dopamine D1 and D2/D3 receptors are able to concurrently influence the excitability of striatal neurons in the dopamine deafferentated striatum. Similar regulation of striatal neurons in vivo may contribute to dopaminergic regulation of basal ganglia output and the ability of dopaminomimetic agents to ameliorate symptoms of dopaminergic deficiency in Parkinson's disease.

A morphometric comparison of the nuclear morphology of fresh and frozen-thawed human zona-bound and unbound sperm

The role of sperm nuclear morphology in zona binding and the effect of cryopreservation on sperm nuclear morphology have been investigated using objective criteria. The nuclear dimensions of fresh and frozen-thawed sperm heads that had been prepared by the swim-up (SU) technique, and bound to human oocytes in vitro, were measured using a computer-assisted image analyzer. These were compared with each other and also to sperm in the SU samples and those that had not bound to the zona pellucida. The unbound (UB) sperm and SU sperm had very similar nuclear morphology. In contrast, the nuclear morphology of the zona-bound (ZB) sperm differed significantly (P < 0.05) from that of the SU and UB sperm. These differences were found specifically between area, breadth, and roundness in the SU and ZB sperm preparations, and between area and roundness in the UB and ZB sperm preparations; the ZB sperm had smaller but rounder nuclei than either the SU or UB sperm. In addition, the frozen-thawed sperm in the SU and UB groups showed a trend towards smaller nuclei than the corresponding fresh groups, whereas the frozen-thawed ZB sperm had significantly (P < 0.05) smaller nuclear dimensions than the fresh ZB sperm. From the present study it appears that the ZB sperm are a morphologically distinct population, although it is not yet clear whether these differences reflect functional events that occur in the sperm head during its maturation or changes at the level of the sperm's DNA after the initial stage of zona binding.(ABSTRACT TRUNCATED AT 250 WORDS)