Preferences in Clinical Care of Individuals With Differences of Sex Development

OBJECTIVES

To identify the most important attributes related to the process of achieving, and outcomes associated with, successful care for differences of sex development (DSD).

METHODS

We developed a best-worst scaling survey administered to 520 DSD stakeholders, including individuals or family members of those with DSD, health care specialists, and patient support and advocacy representatives. Fourteen process-related attributes and 16 outcome-related attributes were identified through qualitative research. We estimated relative importance scores and coefficients from regression analysis to understand the relative importance of attributes and conducted latent class analysis to explore heterogeneity in preferences.

RESULTS

The 3 most important process attributes were (1) good communication between care team and patient/family, (2) care team educated patient/family about condition, and (3) care team incorporates the values of patient/family. The 3 most important outcome attributes were (1) patient satisfaction, (2) patient mental health, and (3) treatment maintains physical health. Latent class analyses showed that respondents had heterogeneous preferences. For process-related attributes, we identified 3 respondent groups: "Patient autonomy and support" (46% of respondents), "Education and care transitions" (18%), and "Shared decision-making" (36%). For outcome-related attributes, we identified 2 respondent groups: "Preserving function and appearance" (59% of respondents) and "Patient health and satisfaction" (41%).

CONCLUSIONS

Outcomes such as patient satisfaction and health were the most important outcome attributes, and good communication and education from the care team were the most important process attributes. Respondents expressed heterogeneous preferences for selected DSD care attributes that providers should consider to improve satisfaction with and quality of DSD care.

Evidence and Recommendation for Guanidinoacetate Methyltransferase Deficiency Newborn Screening

Guanidinoacetate methyltransferase (GAMT) deficiency is an autosomal recessive disorder of creatine biosynthesis due to pathogenic variants in the GAMT gene that lead to cerebral creatine deficiency and neurotoxic levels of guanidinoacetate. Untreated, GAMT deficiency is associated with hypotonia, significant intellectual disability, limited speech development, recurrent seizures, behavior problems, and involuntary movements. The birth prevalence of GAMT deficiency is likely between 0.5 and 2 per million live births. On the basis of small case series and sibling data, presymptomatic treatment with oral supplements of creatine, ornithine, and sodium benzoate, and a protein-restricted diet to reduce arginine intake, appear to substantially improve health and developmental outcomes. Without newborn screening, diagnosis typically happens after the development of significant impairment, when treatment has limited utility. GAMT deficiency newborn screening can be incorporated into the tandem-mass spectrometry screening that is already routinely used for newborn screening, with about 1 per 100 000 newborns screening positive. After a positive screen, diagnosis is established by finding an elevated guanidinoacetate concentration and low creatine concentration in the blood. Although GAMT deficiency is significantly more rare than other conditions included in newborn screening, the feasibility of screening, the low number of positive results, the relative ease of diagnosis, and the expected benefit of presymptomatic dietary therapy led to a recommendation from the Advisory Committee on Heritable Disorders in Newborns and Children to the Secretary of Health and Human Services that GAMT deficiency be added to the Recommended Uniform Screening Panel. This recommendation was accepted in January 2023.

Brucella suis in three dogs: presentation, diagnosis and clinical management

Brucella suis is an emerging, zoonotic disease predominantly affecting dogs and humans that engage in feral pig hunting in Australia and other countries. Although B. suis infection in dogs shares some clinical similarities to the host-adapted species (B. canis), B. suis remains an incompletely understood pathogen in dogs with limited published data on its pathogenesis and clinical features. This case series describes the presentations, diagnosis, and clinical management of B. suis infection in three dogs: (1) a bitch with dystocia, abortion and mastitis; (2) an entire male dog with septic arthritis and presumptive osteomyelitis; and (3) a castrated male dog with lymphadenitis. Unique features of these cases are reported including the first documented detection of B. suis from milk and isolation from lymph nodes of canine patients, as well as the follow-up of pups born to a B. suis-infected bitch. Consistent with previous reports, all three dogs showed a favourable clinical response to combination antibiotic therapy with rifampicin and doxycycline. Individually tailored drug regimens were required based on the clinical presentation and other factors, including owner expectations and compliance with therapy as well as a zoonotic risk assessment (generally considered low, except around time of whelping). The authors include their recommendations for the clinical management of dogs that are at-risk or seropositive for B. suis with or without clinical signs or laboratory-confirmed infection.

A Discrete Choice Analysis Comparing COVID-19 Vaccination Decisions for Children and Adults

IMPORTANCE

COVID-19 vaccination rates in the US remain below optimal levels. Patient preferences for different attributes of vaccine products and the vaccination experience can be important in determining vaccine uptake decisions.

OBJECTIVE

To assess preferences for attributes of adult and pediatric COVID-19 vaccination among US adults.

DESIGN, SETTING, AND PARTICIPANTS

An online survey of a national panel of 1040 US adults was conducted in May and June 2021. A discrete choice analysis was used to measure the relative value of each attribute in the decision to choose a COVID-19 vaccination option for adults or children. Six attributes were used to described hypothetical vaccination options: vaccine effectiveness, mild side effects, rare adverse events, number of doses, time required for vaccination, and regulatory approval. Respondents chose between hypothetical vaccination profiles or no vaccination. Additional survey questions asked about vaccination beliefs, COVID-19 illness experience, COVID-19 risk factors, vaccination status, and opinions about the risk of COVID-19.

EXPOSURES

Respondents chose which vaccine profile they would prefer to receive for themselves (or no vaccination). Respondents then considered an identical set of profiles for a hypothetical child aged 0 to 17 years.

MAIN OUTCOMES AND MEASURES

Relative value of vaccination-related attributes were estimated using Bayesian logit regression. Preference profiles for subgroups were estimated using latent class analyses.

RESULTS

A total of 1040 adults (610 [59%] female; 379 participants [36%] with an age of 55 years and older years) responded to the survey. When asked about vaccination choices for themselves, participants indicated that vaccine effectiveness (95% vs 60%) was a significant attribute (β, 9.59 [95% CrI, 9.20-10.00] vs β, 0.41 [95% CrI, 0-0.80]). Respondents also preferred fewer rare adverse events (β, 6.35 [95% CrI, 5.74-6.86), fewer mild side effects (β, 5.49; 95% CrI, 5.12-5.87), 1 dose (β, 5.41; 95% CrI, 5.04-5.78), FDA approval (β, 6.01; 95% CrI, 5.64-6.41), and shorter waiting times (β, 5.67; 95% CrI, 4.87-6.48). Results were very similar when framing the question as adult or child vaccination, with slightly stronger preference for fewer rare adverse events for children. Latent class analysis revealed 4 groups of respondents: (1) individuals sensitive to safety and regulatory status, (2) individuals sensitive to convenience, (3) individuals who carefully considered all attributes in making their choices, and (4) individuals who rejected the vaccine.

CONCLUSIONS AND RELEVANCE

In this survey study of US adults, the identification of 4 distinct preference groups provides new information to guide communications to support vaccine decision making. In particular, the group that prioritize convenience (less time required for vaccination and fewer doses) may present an opportunity to create actionable strategies to increase vaccination uptake for both adult and pediatric populations.

Health and economic outcomes of newborn screening for infantile-onset Pompe disease

PURPOSE

To estimate health and economic outcomes associated with newborn screening (NBS) for infantile-onset Pompe disease in the United States.

METHODS

A decision analytic microsimulation model simulated health and economic outcomes of a birth cohort of 4 million children in the United States. Universal NBS and treatment was compared with clinical identification and treatment of infantile-onset Pompe disease. Main outcomes were projected cases identified, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) over the life course.

RESULTS

Universal NBS for Pompe disease and confirmatory testing was estimated to cost an additional $26 million annually. Additional medication costs associated with earlier treatment initiation were $181 million; however, $8 million in medical care costs for other services were averted due to delayed disease progression. Infants with screened and treated infantile-onset Pompe disease experienced an average lifetime increase of 11.66 QALYs compared with clinical detection. The ICER was $379,000/QALY from a societal perspective and $408,000/QALY from the health-care perspective. Results were sensitive to the cost of enzyme replacement therapy.

CONCLUSION

Newborn screening for Pompe disease results in substantial health gains for individuals with infantile-onset Pompe disease, but with additional costs.

Knowledge, Attitudes, and Practices Regarding Dietary Sodium in College Students

OBJECTIVE

Test a dietary sodium survey in a US adult population of college students using a survey previously validated in a non-US adult population.

METHODS

Cross-sectional study of a convenience sample of college students from a Midwest (n = 168) and Pacific Island (n = 152) university. Main outcome measures were knowledge, attitudes, and practices regarding dietary sodium (38 items). Sum scores and percentages for constructs were calculated. A score <75% was considered unfavorable; t test or ANOVA were used to examine group differences.

RESULTS

Midwest students were primarily non-Hispanic White individuals (81%) and 65% female. Pacific Island students were predominantly Asian (51%) and 66% female. Mean ± SD construct scores (percentage) for knowledge, attitudes, and practices were 58.69 ± 10.62, 63.96 ± 16.18, 66.00 ± 12.34 (Midwest) and 57.54 ± 10.93, 64.84 ± 14.96, 64.94 ± 13.18 (Pacific Island), respectively; there were no significant differences between schools or race.

CONCLUSIONS AND IMPLICATIONS

College students scored low in knowledge, attitudes, and practices regarding sodium. Results from this formative study may inform assessment strategies in future dietary sodium interventions.

MSR1 repeats modulate gene expression and affect risk of breast and prostate cancer

Background

MSR1 repeats are a 36-38 bp minisatellite element that have recently been implicated in the regulation of gene expression, through copy number variation (CNV).

Patients and methods

Bioinformatic and experimental methods were used to assess the distribution of MSR1 across the genome, evaluate the regulatory potential of such elements and explore the role of MSR1 elements in cancer, particularly non-familial breast cancer and prostate cancer.

Results

MSR1s are predominately located at chromosome 19 and are functionally enriched in regulatory regions of the genome, particularly regions implicated in short-range regulatory activities (H3K27ac, H3K4me1 and H3K4me3). MSR1-regulated genes were found to have specific molecular roles, such as serine-protease activity (P = 4.80 × 10-7) and ion channel activity (P = 2.7 × 10-4). The kallikrein locus was found to contain a large number of MSR1 clusters, and at least six of these showed CNV. An MSR1 cluster was identified within KLK14, with 9 and 11 copies being normal variants. A significant association with the 9-copy allele and non-familial breast cancer was found in two independent populations (P = 0.004; P = 0.03). In the white British population, the minor allele conferred an increased risk of 1.21-3.51 times for all non-familial disease, or 1.7-5.3 times in early-onset disease. The 9-copy allele was also found to be associated with increased risk of prostate cancer in an independent population (odds ratio = 1.27-1.56; P =0.009).

Conclusions

MSR1 repeats act as molecular switches that modulate gene expression. It is likely that CNV of MSR1 will affect risk of development of various forms of cancer, including that of breast and prostate. The MSR1 cluster at KLK14 represents the strongest risk factor identified to date in non-familial breast cancer and a significant risk factor for prostate cancer. Analysis of MSR1 genotype will allow development of precise stratification of disease risk and provide a novel target for therapeutic agents.

Examination of the relationship of diet quality with cardiometabolic risk factors in apparently healthy college students

BACKGROUND

Preliminary evidence indicates that subclinical cardiometabolic abnormalities are present in apparently healthy nonobese young adults. Poor dietary habits may be a contributing factor.

OBJECTIVE

The objective of this study was to examine the presence of cardiometabolic abnormalities in apparently healthy college students and to assess the relationship between diet quality and cardiometabolic risk factors.

METHODS

Cross-sectional anthropometric, lipidemia, and glucose tolerance, blood pressure, and dietary Healthy Eating Index (HEI) data were collected (April 2015). Participants were undergraduate students. Ordinary least squares regression was used to examine associations between diet quality and cardiometabolic risk factors.

RESULTS

Participants (n = 147) were primarily nonHispanic Caucasian between 18 and 22 years and largely nonobese (95.0% of females, 85.1% of males). Total HEI score was 56.1 ± 16.1 for females and 53.2 ± 15.0 for males. Mean biochemical and clinical outcomes fell within normal limits. However, 71.0% of females and 80.9% of males met ≥1 or more metabolic syndrome criteria. HEI was not related to health outcomes.

CONCLUSIONS

Cardiometabolic abnormalities are present in a large proportion of apparently healthy undergraduates which may place them at risk for future cardiometabolic complications. There was no relationship between diet quality and cardiometabolic health.

Use of a choice survey to identify adult, adolescent and parent preferences for vaccination in the United States

Background

Adult and adolescent vaccination rates are far below coverage targets in the United States. Our objective was to identify the most influential factors related to vaccine uptake among adults, adolescents, and parents of adolescents (parents) in the United States.

Methods

We used a fractional factorial design to create a binary choice survey to evaluate preferences for vaccination. The national survey was fielded to a sample of adults, adolescents ages 13–17 years, and parents, using a national probability-based online research panel in November 2015. Respondents were presented with 5 profiles of a hypothetical vaccine and asked in a series of questions whether they would accept each vaccine. We analyzed the binary choice data using logistic regression in STATA v13 (College Station, TX) to calculate the odds that a participant would choose to accept the vaccine.

Results

We received completed responses from 334 (51%) of 652 adults, 316 (21%) of 1516 adolescents, and 339 (33%) of 1030 parents. Respondents were generally representative of the U.S. population. Vaccine effectiveness was the most influential factor in the choice to vaccinate for all groups. Other most influential factors were primary care provider (PCP) recommendation and the out-of-pocket cost of the vaccine. Other factors such as risk of illness, risk of vaccine side effects, vaccination location, and time for vaccination were not important in the decision to get vaccinated.

Conclusions

Adults, adolescents, and parents are most sensitive to vaccine effectiveness, PCP recommendation, and out-of-pocket cost for vaccination in their decision to get vaccinated. Strong PCP recommendations that focus on vaccine effectiveness and health care policies that minimize out-of-pocket costs for vaccinations may increase vaccine uptake by adults and adolescents.

Electronic supplementary material

The online version of this article (10.1186/s41687-019-0135-0) contains supplementary material, which is available to authorized users.

A Cost-Effectiveness Analysis of Vaccination for Prevention of Herpes Zoster and Related Complications: Input for National Recommendations

BACKGROUND

The U.S. Advisory Committee on Immunization Practices recently developed recommendations for use of a new recombinant zoster vaccine (RZV).

OBJECTIVE

To evaluate the cost-effectiveness of vaccination with RZV compared with zoster vaccine live (ZVL) and no vaccination, the cost-effectiveness of vaccination with RZV for persons who have previously received ZVL, and the cost-effectiveness of preferential vaccination with RZV over ZVL.

DESIGN

Simulation (state-transition) model using U.S. epidemiologic, clinical, and cost data.

DATA SOURCES

Published data.

TARGET POPULATION

Hypothetical cohort of immunocompetent U.S. adults aged 50 years or older.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal and health care sector.

INTERVENTION

Vaccination with RZV (recommended 2-dose regimen), vaccination with ZVL, and no vaccination.

OUTCOME MEASURES

The primary outcome measure was the incremental cost-effectiveness ratio (ICER).

RESULTS OF BASE-CASE ANALYSIS

For vaccination with RZV compared with no vaccination, ICERs ranged by age from $10 000 to $47 000 per quality-adjusted life-year (QALY), using a societal perspective and assuming 100% completion of the 2-dose RZV regimen. For persons aged 60 years or older, ICERs were less than $60 000 per QALY. Vaccination with ZVL was dominated by vaccination with RZV for all age groups 60 years or older.

RESULTS OF SENSITIVITY ANALYSIS

Results were most sensitive to changes in vaccine effectiveness, duration of protection, herpes zoster incidence, and probability of postherpetic neuralgia. Vaccination with RZV after previous administration of ZVL yielded an ICER of less than $60 000 per QALY for persons aged 60 years or older. In probabilistic sensitivity analyses, RZV remained the preferred strategy in at least 95% of simulations, including those with 50% completion of the second dose.

LIMITATION

Few data were available on risk for serious adverse events, adherence to the recommended 2-dose regimen, and probability of recurrent zoster.

CONCLUSION

Vaccination with RZV yields cost-effectiveness ratios lower than those for many recommended adult vaccines, including ZVL. Results are robust over a wide range of plausible values.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Determining attitudinal and behavioral factors concerning milk and dairy intake and their association with calcium intake in college students

BACKGROUND/OBJECTIVES

Average intake of calcium among college students is below the recommended intake, and knowledge surrounding the attitudinal and behavioral factors that influence milk and dairy intake, a primary food source of calcium, is limited. The purpose of this study was to evaluate college students' attitudes and behaviors concerning milk and dairy consumption and their association with calcium intake.

SUBJECTS/METHODS

Participants were 1,730 undergraduate students who completed an online survey (SurveyMonkey) as part of baseline data collection for a social marketing dairy campaign. The online survey assessed attitudes and behaviors concerning milk and dairy intake, and calcium intake. Questions about milk- and dairy-related attitudes and behaviors were grouped into 14 factors using factor analysis. Predictors of calcium intake were then evaluated.

RESULTS

Median calcium intake across all participants was 928.6 mg/day, with males consuming higher calcium intakes than females (P < 0.001). Adjusted for gender, calcium intakes were most strongly (and positively) correlated with associating milk with specific eating occasions and availability (i.e., storing calcium-rich foods in one's dorm or apartment) (both P < 0.001). Other correlates of calcium intake included: positive-viewing milk as healthy (P = 0.039), having family members who drink milk) (P = 0.039), and taking calcium supplements (P = 0.056); and negative-parent rules concerning milk (P = 0.031) and viewing milk in dining halls negatively (P = 0.05).

CONCLUSIONS

Calcium intakes among college students enrolled in the current study was below the recommended dietary allowance of 1,000 mg/day, reinforcing the need for dietary interventions in this target population, especially females. Practitioners and researchers should consider the factors found here to impact calcium intake, particularly associating milk with specific eating occasions (e.g., milk with breakfast) and having calcium-rich foods available in the dorm room or apartment, as intervention strategies in future efforts aimed at promoting milk and dairy foods and beverages for improved calcium intake in college students.

Milk Vending Does Not Improve College Students’ Milk and Calcium Intakes

In the transition from adolescence to young adulthood, overall diet quality decreases, including a reduction in both dairy and calcium consumption. The objective of this pilot study was to determine the impact of milk vending on milk and calcium intakes in college students. Participants were 124 college students living in dorms at a large public university (Fall 2012). Milk vending machines were installed in two campus dorms. Before and 2 months after installation, students were surveyed about milk and calcium intakes, as well as attitudes regarding milk vending. Sales data for the newly installed machines were also collected between the pre- and posttest surveys. Students reported similar milk and calcium consumption before and after the intervention. Mean calcium intakes were lower than the recommended dietary allowance for students in either life stage group (18 years old or 19 years and older). Milk vending sales data showed that during the study period, approximately nine bottles of milk were bought each day from the two dorms combined. Results from this study suggest that milk vending alone may not be an effective strategy for preventing the commonly observed decrease in milk and calcium intakes among college students.

Variant haploinsufficiency and phenotypic non-penetrance in PRPF31-associated retinitis pigmentosa

Retinitis pigmentosa (RP) is a genetically heterogenous group of inherited disorders, characterized by death of the retinal photoreceptor cells, leading to progressive visual impairment. One form of RP is caused by mutations in the ubiquitously expressed splicing factor, PRPF31, this form being known as RP11. An intriguing feature of RP11 is the presence of non-penetrance, which has been observed in the majority of PRPF31 mutation-carrying families. In contrast to variable expressivity, which is highly pervasive, true non-penetrance is a very rare phenomenon in Mendelian disorders. In this article, the molecular mechanisms underlying phenotypic non-penetrance in RP11 are explored. It is an elegant example of how our understanding of monogenic disorders has evolved from studying only the disease gene, to considering a mutation on the genetic background of the individual - the logical evolution in this genomic era.

Establishing national noncommunicable disease surveillance in a developing country: a model for small island nations

Objective To describe the surveillance model used to develop the first national, population-based, multiple noncommunicable disease (NCD) registry in the Caribbean (one of the first of its kind worldwide); registry implementation; lessons learned; and incidence and mortality rates from the first years of operation. Methods Driven by limited national resources, this initiative of the Barbados Ministry of Health (MoH), in collaboration with The University of the West Indies, was designed to collect prospective data on incident stroke and acute myocardial infarction (MI) (heart attack) cases from all health care facilities in this small island developing state (SIDS) in the Eastern Caribbean. Emphasis is on tertiary and emergency health care data sources. Incident cancer cases are obtained retrospectively, primarily from laboratories. Deaths are collected from the national death register. Results Phased introduction of the Barbados National Registry for Chronic NCDs ("the BNR") began with the stroke component ("BNR-Stroke," 2008), followed by the acute MI component ("BNR-Heart," 2009) and the cancer component ("BNR-Cancer," 2010). Expected case numbers projected from prior studies estimated an average of 378 first-ever stroke, 900 stroke, and 372 acute MI patients annually, and registry data showed an annual average of about 238, 593, and 349 patients respectively. There were 1 204 tumors registered in 2008, versus the expected 1 395. Registry data were used to identify public health training themes. Success required building support from local health care professionals and creating island-wide registry awareness. With spending of approximately US$ 148 per event for 2 200 events per year, the program costs the MoH about US$ 1 per capita annually. Conclusions Given the limited absolute health resources available to SIDS, combined surveillance should be considered for building a national NCD evidence base. With prevalence expected to increase further worldwide, Barbados' experiences are offered as a "road map" for other limited-resource countries considering national NCD surveillance.

Incorporation of eicosapentaenioic and docosahexaenoic acids into breast adipose tissue of women at high risk of breast cancer: a randomized clinical trial of dietary fish and n-3 fatty acid capsules

SCOPE

The fatty acid profile of dietary lipids is reflected in mammary adipose tissue and may influence mammary gland biology and cancer risk. To determine the effects of fish consumption on breast adipose tissue fatty acids, we conducted a study of fish versus n-3 PUFA supplements in women at increased risk of breast cancer.

METHODS AND RESULTS

High risk women were randomized to comparable doses of marine n-3 PUFAs as canned salmon + albacore or capsules for 3 months. Pre- and posttreatment fatty acid profiles were obtained by GC. Dietary fish (n = 12) and n-3 PUFA capsules (n = 13) yielded increased eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plasma (p < 0.0001), erythrocyte membranes (p < 0.0001), and breast fat (p < 0.01) at 3 months. Women taking capsules had higher plasma and erythrocyte membrane EPA changes (∼four versus twofold, p = 0.002), without significant differences in DHA. Increases in breast adipose EPA, DHA were similar for both groups. Higher BMI correlated with smaller changes in plasma, erythrocyte membrane EPA, and breast adipose EPA, DHA. Adherence was excellent at 93.9% overall and higher in the fish arm (p = 0.01).

CONCLUSION

Fish provides an excellent source of n-3 PUFAs that increases breast adipose EPA, DHA similar to supplements and represents a well-tolerated intervention for future studies of the impact of n-3 PUFAs and dietary patterns on breast cancer.

The Effect of Temperature and Parental Age on Recombination and Nondisjunction in CAENORHABDITIS ELEGANS

The effect of temperature and parental age on recombination frequency in C. elegans was studied between pairs of closely linked markers on linkage groups I and V. In the regions studied, recombination frequency varied three-fold over the temperature range 13.5 degrees to 26 degrees . Temperature-shift experiments indicated that a temperature-sensitive recombination event occurs approximately 50 oocytes prior to fertilization. Recombination frequency was observed to decrease with maternal age. The greatest decrease was observed in the first 24 hours of egg production. The frequency of male progeny, a measure of X-chromosome nondisjunction was also studied. This frequency increased with elevated temperature and age of the parent.

Caenorhabditis elegans dpy-5 is a cuticle procollagen processed by a proprotein convertase

Genetic analysis of the nematode Caenorhabditis elegans reveals that all dpy-5 alleles are dominant suppressors of bli-4 blistering. Molecular cloning of dpy-5 establishes that it encodes a cuticle procollagen, defects in which are responsible for the short-body, dumpy phenotype. The null mutation, e907 removes the entire coding region, whereas the dpy-5 reference allele, e61, contains a nonsense substitution. RT-PCR analysis and a dpy-5::gfp fusion show that dpy-5 is expressed only in hypodermal cells at all post-embryonic life-cycle stages. Variable expression of dpy-5 in V lineage-derived seam cells suggests an alternative regulatory mechanism in these cells. The dpy-5 gene product contains an Arg-X-X-Arg cleavage motif that could be recognized by a proprotein convertase, such as BLI-4. Mutation of this site cause a dominant dumpy phenotype suggesting Dpy-5 procollagen requires processing for normal cuticle production.

PhyloBLAST: facilitating phylogenetic analysis of BLAST results

PhyloBLAST is an internet-accessed application based on CGI/Perl programming that compares a users protein sequence to a SwissProt/TREMBL database using BLAST2 and then allows phylogenetic analyses to be performed on selected sequences from the BLAST output. Flexible features such as ability to input your own multiple sequence alignment and use PHYLIP program options provide additional web-based phylogenetic analysis functionality beyond the analysis of a BLAST result.

Tuberculosis at the end of the 20th century in England and Wales: results of a national survey in 1998

BACKGROUND

A national survey of tuberculosis was conducted in England and Wales in 1998 to obtain detailed information on the occurrence of the disease and recent trends. This survey also piloted the methodology for enhanced tuberculosis surveillance in England and Wales and investigated the prevalence of HIV infection in adults with tuberculosis.

METHODS

Clinical and demographic data for all cases diagnosed during 1998 were obtained, together with microbiological data where available. Annual incidence rates in the population were estimated by age, sex, ethnic group, and geographical region using denominators from the 1998 Labour Force Survey. Incidence rates in different subgroups of the population were compared with the rates observed in previous surveys. The tuberculosis survey database for 1998 was matched against the Communicable Disease Surveillance Centre HIV/AIDS database to estimate the prevalence of HIV co-infection in adult patients with tuberculosis.

RESULTS

A total of 5658 patients with tuberculosis were included in the survey in England and Wales (94% of all formally notified cases during the same period), giving an annual rate of 10.93 per 100 000 population (95% CI 10.87 to 10.99). This represented an increase of 11% in the number of cases since the survey in 1993 and 21% since 1988. In many regions case numbers have remained little changed since 1988, but in London an increase of 71% was observed. The number of children with tuberculosis has decreased by 10% since 1993. Annual rates of tuberculosis per 100 000 population have continued to decline among the white population (4.38) and those from the Indian subcontinent, although the rate for the latter has remained high at 121 per 100 000. Annual rates per 100 000 have increased in all other ethnic groups, especially among those of black African (210) and Chinese (77.3) origin. Over 50% of all patients were born outside the UK. Recent entrants to the UK had higher rates of the disease than those who had been in the country for more than 5 years or who had been born in the UK. An estimated 3.3% of all adults with tuberculosis were co-infected with HIV.

CONCLUSIONS

The epidemiology of tuberculosis continues to change in England and Wales and the annual number of cases is rising. More than one third of cases now occur in young adults and rates are particularly high in those recently arrived from high prevalence areas of the world. The geographical distribution is uneven with urban centres having the highest rates. The increase in the number of cases in London is particularly large. Tuberculosis in patients co-infected with HIV makes a small but important contribution to the overall increase, particularly in London. To be most effective and to make the most efficient use of resources, tuberculosis prevention and control measures must be based on accurate and timely information on the occurrence of disease. A new system of continuous enhanced tuberculosis surveillance was introduced in 1999, based on the methodology developed in this national survey.

Mutational analysis of bli-4/kpc-4 reveals critical residues required for proprotein convertase function in C. elegans

Kex2/subtilisin-like proteinase activity is required for the production of the adult cuticle in the nematode Caenorhabditis elegans. Deletion of the carboxy termini of four of the bli-4/kpc-4 convertase isoforms results in blistering of the adult cuticle. The blisters vary in severity (expressivity) and are not evident in all individuals (reduced penetrance). We have isolated 13 bli-4/kpc-4 mutants that arrest development in late embryogenesis. Using a PCR-based heteroduplex technique, we have identified nucleotide changes responsible for eight of these lethal mutations. The lesions reside within the first 12 exons that are shared by all of the bli-4/kpc-4 gene products, with the majority of mutations clustered within the protease domain. This finding suggests that the protease domain represents a large mutable target. Among these mutations, allele h384 represents a molecular null mutant in which the catalytically essential serine residue (Ser415) is replaced by phenylalanine. Novel missense mutations that change the identity of amino acids evolutionary conserved in all kex2/subtilisin-convertases highlight critical residues essential for activity. We examined the functional activity of BLI-4/KPC-4 products expressed from several lethal mutants by testing their effect on the variable penetrance of blistering exhibited by the e937 allele. We found that the combination of a bli-4/kpc-4 lethal mutation in trans to the bli-4(e937) mutation was sufficient to cause severe blistering in heteroallelic progeny, even in the presence of a known dominant suppressor.

A look at the Caenorhabditis elegans Kex2/Subtilisin-like proprotein convertase family

Significant advances have recently been made in our understanding of the mechanisms of activation of proteins that require processing. Often this involves endoproteolytic cleavage of precursor forms at basic residues, and is carried out by a group of serine endoproteinases, termed the proprotein convertases. In mammals, seven different convertases have been identified to date. These act in both the regulated secretory pathway for the processing of prohormones and proneuropeptides and in the constitutive secretory pathway, in which a variety of proproteins are activated endoproteolytically. The recently completed sequence of the nematode Caenorhabditis elegans genome affords a unique opportunity to examine the entire proprotein convertase family in a multicellular organism. Here we review the nature of the family, emphasising the structural features, characteristic of the four nematode genes, that supply all of the necessary functions unique to this group of serine endoproteinases. Studies of the C. elegans genes not only provide important information about the evaluation of this gene family but should help to illuminate the roles of these proteins in mammalian systems. BioEssays 22:545-553, 2000.

EMB-30: an APC4 homologue required for metaphase-to-anaphase transitions during meiosis and mitosis in Caenorhabditis elegans

Here we show that emb-30 is required for metaphase-to-anaphase transitions during meiosis and mitosis in Caenorhabditis elegans. Germline-specific emb-30 mutant alleles block the meiotic divisions. Mutant oocytes, fertilized by wild-type sperm, set up a meiotic spindle but do not progress to anaphase I. As a result, polar bodies are not produced, pronuclei fail to form, and cytokinesis does not occur. Severe-reduction-of-function emb-30 alleles (class I alleles) result in zygotic sterility and lead to germline and somatic defects that are consistent with an essential role in promoting the metaphase-to-anaphase transition during mitosis. Analysis of the vulval cell lineages in these emb-30(class I) mutant animals suggests that mitosis is lengthened and eventually arrested when maternally contributed emb-30 becomes limiting. By further reducing maternal emb-30 function contributed to class I mutant animals, we show that emb-30 is required for the metaphase-to-anaphase transition in many, if not all, cells. Metaphase arrest in emb-30 mutants is not due to activation of the spindle assembly checkpoint but rather reflects an essential emb-30 requirement for M-phase progression. A reduction in emb-30 activity can suppress the lethality and sterility caused by a null mutation in mdf-1, a component of the spindle assembly checkpoint machinery. This result suggests that delaying anaphase onset can bypass the spindle checkpoint requirement for normal development. Positional cloning established that emb-30 encodes the likely C. elegans orthologue of APC4/Lid1, a component of the anaphase-promoting complex/cyclosome, required for the metaphase-to-anaphase transition. Thus, the anaphase-promoting complex/cyclosome is likely to be required for all metaphase-to-anaphase transitions in a multicellular organism.

Mutational accessibility of essential genes on chromosome I(left) in Caenorhabditis elegans

We have analyzed a region of approximately 5.4 million base pairs for mutations, which under standard laboratory conditions result in developmental arrest, sterility, or maternal-effect lethality in Caenorhabditis elegans. Lethal mutations were isolated, maintained, and genetically manipulated as homozygotes using sDp2--a duplication of the left half of chromosome I. All of the lethals and rearrangements used in this analysis were balanced by sDp2. Relatively low doses of mutagen, (approximately 15 mM ethylmethane sulfate; EMS), were used so as to limit the occurrence of second-site mutations, thus increasing the probability of recovering single nucleotide substitutions. Treatment of over 32,400 marked chromosomes resulted in 486 analyzed mutations. In this paper, we add 133 previously unidentified let genes, isolated in the EMS screens, and one let gene identified by a gamma-ray induced mutation, to our collection of 103 essential genes. We also recovered lethal alleles of genes for which visible mutants already existed. In total, eight deficiencies and alleles of 237 essential genes were identified. Eighty-nine of the previously unidentified let genes are represented by more than one lethal allele. Statistical analysis indicates a minimum estimate of 400 essential genes in the region of chromosome I balanced by sDp2. This region occupies approximately half of chromosome I, and contains over 1135 protein-coding genes predicted from the genomic sequence data. Thus, approximately one-third of the predicted genes are estimated to be essential. Of these approximately 60% are represented by lethal alleles. Less than 2% of the lethal-bearing strains recovered in our analysis, including the eight genetically definable deficiencies, carried more than one lethal mutation. Several screens were used to recover mutations for this analysis. Because all the mutations were isolated using the same balancer, under similar screening conditions, it was possible to compare intervals within the sDp2 region with each other. The fraction of essential genes that present relatively large targets for EMS was highest within the central cluster (dpy-5 to unc-13).

Sodium pump isoforms in xenotransplantation: importance of biochemical compatibility

BACKGROUND

Xenotransplantation of pig hearts to humans could be hampered by the reportedly reduced affinity for digoxin of pig heart. We examined the hypothesis that expression of the individual alpha-subunit isoforms of the sodium pump [Na(+),K(+)-ATPase (NKA)], the receptor for the plant-derived cardiac glycosides, may be responsible for this difference.

METHODS

We used a NKA-inhibition assay in combination with Western analysis, immunohistochemistry, and phosphorylation of the NKA alpha subunit to identify the distribution and expression of alpha isoforms in four chambers of porcine and human hearts.

RESULTS

We confirmed that tissue from porcine heart is less sensitive to digitalis (IC(50) = 1740 nmol/L) when compared with human heart (IC(50) = 840 nmol/L), whereas porcine cerebral cortex-mix had an affinity comparable to that of human heart (IC(50) = 910 nmol/L). Our data show that porcine cerebral cortex-mix and human heart contain all three alpha isoforms, whereas porcine heart expresses only the alpha1 isoform.

CONCLUSIONS

The different expressions of sodium pump isoforms in human vs porcine cardiac tissues suggests that porcine hearts may not be pharmacologically or endocrinologically compatible when used in humans. Studies of both pharmacologic and endocrinologic tissue compatibility are needed prior to selection of organs for xenotransplantation.

Components of the spindle-assembly checkpoint are essential in Caenorhabditis elegans

The spindle-assembly checkpoint ensures that, during mitosis and meiosis, chromosomes do not segregate until they are properly attached to the microtubules of the spindle. Here we show that mdf-1 and mdf-2 are components of the spindle-assembly checkpoint in Caenorhabditis elegans, and are essential for the long-term survival and fertility of this organism. Loss of function of either of these genes leads to the accumulation of a variety of defects, including chromosome abnormalities, X-chromosome non-disjunction or loss, problems in gonad development, and embryonic lethality. Antibodies that recognize the MDF-2 protein localize to nuclei of the cleaving embryo in a cell-cycle-dependent manner. mdf-1, a gene encoding a product that interacts with MDF-2, is required for cell-cycle arrest and proper chromosome segregation in premeiotic germ cells treated with nocodazole, a microtubule-depolymerizing agent. In the absence of mdf gene products, errors in chromosome segregation arise and accumulate, ultimately leading to genetic lethality.

Functional genomics in Caenorhabditis elegans: An approach involving comparisons of sequences from related nematodes

Comparative genomic analysis was used to investigate the gene structure of the bli-4 locus from two related Caenorhabditis species, C. elegans and C. briggsae. In C. elegans, bli-4 is a complex gene encoding a member of the kex2/subtilisin-like family of proprotein convertases. Genomic sequence comparisons coupled with RT-PCR analysis identified five additional coding exons that had not been identified previously using standard recombinant DNA techniques. The C. briggsae gene was able to rescue both viable blistered and developmentally arrested mutants of C. elegans bli-4, demonstrating functional conservation. In addition, deletion analysis of conserved sequences outside of coding regions, combined with phenotypic rescue experiments, identified regulatory elements that alter the expression of the bli-4 gene. These results demonstrate the utility of genomic sequence comparisons of homologous genes in related species as an effective tool with which to dissect the functional information of complex genes.

Alpha 2 isoform of the Na,K-adenosine triphosphatase is reduced in temporal cortex of bipolar individuals

BACKGROUND

The pathophysiology of bipolar illness has been associated with changes in transmembrane ion flux and redistribution of biologically active ions. The recent identification of multiple isoforms of Na,K-adenosine triphosphatase (ATPase) alpha and beta subunits raises the possibility of altered pump isoform expression.

METHODS

We determined Na,K-ATPase alpha subunit expression in postmortem temporal cortex gray matter from individuals suffering from bipolar disorder, schizoaffective disorder, schizophrenia, and matched normal controls. Quantification of isoform expression was accomplished via densitometric scanning of Western blots utilizing isoform-specific antibodies.

RESULTS

Bipolar individuals exhibited a significant reduction in the abundance of the alpha 2 isoform of Na,K-ATPase compared to normal controls. Schizophrenic and schizo-affective brains were not significantly different from normal controls.

CONCLUSION

These data suggest that previously observed abnormalities in regulation and distribution of ions in bipolar illness may be related to specific alpha 2 dysregulation.

Mapping a telomere using the translocation eT1(III;V) in Caenorhabditis elegans

In Caenorhabditis elegans, individuals heterozygous for a reciprocal translocation produce reduced numbers of viable progeny. The proposed explanation is that the segregational pattern generates aneuploid progeny. In this article, we have examined the genotype of arrested embryonic classes. Using appropriate primers in PCR amplifications, we identified one class of arrested embryo, which could be readily recognized by its distinctive spot phenotype. The corresponding aneuploid genotype was expected to be lacking the left portion of chromosome V, from the eT1 breakpoint to the left (unc-60) end. The phenotype of the homozygotes lacking this DNA was a stage 2 embryonic arrest with a dark spot coinciding with the location in wild-type embryos of birefringent gut granules. Unlike induced events, this deletion results from meiotic segregation patterns, eliminating complexity associated with unknown material that may have been added to the end of a broken chromosome. We have used the arrested embryos, lacking chromosome V left sequences, to map a telomere probe. Unique sequences adjacent to the telomeric repeats in the clone cTel3 were missing in the arrested spot embryo. The result was confirmed by examining aneuploid segregants from a second translocation, hT1(I;V). Thus, we concluded that the telomere represented by clone cTel3 maps to the left end of chromosome V. In this analysis, we have shown that reciprocal translocations can be used to generate segregational aneuploids. These aneuploids are deleted for terminal sequences at the noncrossover ends of the C. elegans autosomes.

Interpreting a sequenced genome: toward a cosmid transgenic library of Caenorhabditis elegans

We have generated a library of transgenic Caenorhabditis elegans strains that carry sequenced cosmids from the genome of the nematode. Each strain carries an extrachromosomal array containing a single cosmid, sequenced by the C. elegans Genome Sequencing Consortium, and a dominate Rol-6 marker. More than 500 transgenic strains representing 250 cosmids have been constructed. Collectively, these strains contain approximately 8 Mb of sequence data, or approximately 8% of the C. elegans genome. The transgenic strains are being used to rescue mutant phenotypes, resulting in a high-resolution map alignment of the genetic, physical, and DNA sequence maps of the nematode. We have chosen the region of chromosome III deleted by sDf127 and not covered by the duplication sDp8(III;I) as a starting point for a systematic correlation of mutant phenotypes with nucleotide sequence. In this defined region, we have identified 10 new essential genes whose mutant phenotypes range from developmental arrest at early larva, to maternal effect lethal. To date, 8 of these 10 essential genes have been rescued. In this region, these rescues represent approximately 10% of the genes predicted by GENEFINDER and considerably enhance the map alignment. Furthermore, this alignment facilitates future efforts to physically position and clone other genes in the region. [Updated information about the Transgenic Library is available via the Internet at http://darwin.mbb.sfu.ca/imbb/dbaillie/cos mid.html.]

Genetic analysis of sterile mutants in the dpy-5 unc-13 (I) genomic region of Caenorhabditis elegans

Essential genes were identified in the 1.5-map unit dpy-5 unc-13 region of chromosome I in the Caenorhabditis elegans genome by rescuing lethal mutations using the duplication sDp2. In this paper, we report the mapping and complementation testing of lethal mutations, 45 of which identify 18 new, essential genes. This analysis brings the number of essential genes defined by the sDp2 rescue of lethal mutants to 97; 64 of these map between dpy-5 and unc-13. 61% of these essential genes are identified by more than one allele. Positioning of the mutations was done using the breakpoints of six duplications. The mutant phenotypes of 14 loci essential for fertility were characterized by Nomarski microscopy and DAPI staining. None of the mutants were rescued by wild-type male sperm. The cytological data showed that four genes produced mutants with defects in gonadogenesis. let-395. let-603, let-605 and let-610. Mutations in seven genes, let-355, let-367, let-384, let-513, let-544, let-545 and let-606, affected germ cell proliferation or gametogenesis. Mutants for the remaining three genes, let-370, let-599 and let-604, produced eggs that failed to develop or hatch. thereby acting as maternal effect lethals. We observed a nonrandom distribution of arrest phenotypes with regard to map position.

The role of chromosome ends during meiosis in Caenorhabditis elegans

Chromosome ends have been implicated in the meiotic processes of the nematode Caenorhabditis elegans. Cytological observations have shown that chromosome ends attach to the nuclear membrane and adopt kinetochore functions. In this organism, centromeric activity is highly regulated, switching from multiple spindle attachments all along the chromosome during mitotic division to a single attachment during meiosis. C. elegans chromosomes are functionally monocentric during meiosis. Earlier genetic studies demonstrated that the terminal regions of the chromosomes are not equivalent in their meiotic potentials. There are asymmetries in the abilities of the ends to recombine when duplicated or deleted. In addition, mutations in single genes have been identified that mimic the meiotic effects of a terminal truncation of the X chromosome. The recent cloning and characterization of the C. elegans telomeres has provided a starting point for the study of chromosomal elements mediating the meiotic process.

Mutant rec-1 eliminates the meiotic pattern of crossing over in Caenorhabditis elegans

Meiotic crossovers are not randomly distributed along the chromosome. In Caenorhabditis elegans the central portions of the autosomes have relatively few crossovers compared to the flanking regions. We have measured the frequency of crossing over for several intervals across chromosome I in strains mutant for rec-1. The chromosome is approximately 50 map units in both wild-type and rec-1 homozygotes, however, the distribution of exchanges is very different in rec-1. Map distances expand across the gene cluster and contract near the right end of the chromosome, resulting in a genetic map more consistent with the physical map. Mutations in two other genes, him-6 and him-14, also disrupted the distribution of exchanges. Unlike rec-1, individuals homozygous for him-6 and him-14 had an overall reduction in the amount of crossing over accompanied by a high frequency of nondisjunction and reduced egg hatching. In rec-1; him-6 and rec-1; him-14 homozygotes the frequency of crossing over was characteristic of the Him mutant phenotype, whereas the distribution of the reduced number of exchanges was characteristic of the Rec-1 pattern. It appears that these gene products play a role in establishing the meiotic pattern of exchange events.

The bli-4 locus of Caenorhabditis elegans encodes structurally distinct kex2/subtilisin-like endoproteases essential for early development and adult morphology

Many secreted proteins are excised from inactive proproteins by cleavage at pairs of basic residues. Recent studies have identified several serine endoproteases that catalyze this cleavage in the secretory pathways of yeast and metazoans. These enzymes belong to the kex2/subtilisin-like family of proprotein convertases. In this paper we describe the molecular characterization of the bli-4 gene from Caenorhabditis elegans, which was shown previously by genetic analysis of lethal mutants to be essential for the normal development of this organism. Sequencing of cDNA and genomic clones has revealed that bli-4 encodes gene products related to the kex2/subtilisin-like family of proprotein convertases. Analysis of bli-4 cDNAs has predicted four protein products, which we have designated blisterases A, B, C, and D. These protein products share a common amino terminus, but differ at the carboxyl termini, and are most likely produced from alternatively spliced transcripts. We have determined the molecular lesions for three bli-4 alleles (h199, h1010, and q508) that result in developmental arrest during late embryogenesis. In each case, the molecular lesions are within exons common to all of the BLI-4 isoforms. The original defining allele of bli-4, e937, is completely viable yet exhibits blistering of the adult cuticle. Molecular analysis of this allele revealed a deletion that removes exon 13, which is unique to blisterase A. No RNA transcript corresponding to exon 13 is detectable in the blistered mutants. These findings suggest that blisterase A is required for the normal function of the adult cuticle.(ABSTRACT TRUNCATED AT 250 WORDS)

Location of N2,N2-dimethylguanosine-specific tRNA methyltransferase

Most steps in the maturation of nuclear coded tRNAs occur in the nucleus in eukaryotic cells, but little is known as to the intranuclear location of this RNA maturation pathway. Indirect immunofluorescence experiments using antibody to N2,N2 dimethylguanosine-specific tRNA methyltransferase, a tRNA processing enzyme, and to Nup1p, a nuclear pore protein, show that both locate to the nuclear periphery in wild type cells. Staining of the nuclear membrane is more uniform with anti-Trm1p than the punctate staining observed with antibodies recognizing Nup1p. Biochemical fractionation experiments comparing fractionation of Trm1p with Nup1p, tRNA splicing ligase, and tRNA splicing endonuclease show that Trm1p behaves more like the known peripheral nuclear membrane proteins, Nup1p and tRNA splicing ligase, than like the integral membrane protein, tRNA splicing endonuclease. Cells overproducing Trm1p also concentrate it to the nuclear periphery. Thus, the site(s) of interaction of Trm1p are not easily saturable and are likely to be in excess to Trm1p. Trm1p is shared by mitochondria and the nucleus. Cells transformed with a gene coding Trm1p with a mutant nuclear targeting signal display cytoplasmic staining and an enzyme with increased solubility when compared to the solubility of wild type enzyme. Thus, mutations that prevent the enzyme from entering the nucleus result in an increase in its cytosolic but not mitochondrial concentration suggesting that the mitochondrial/nuclear distribution of Trm1p is not due solely to competition of mitochondrial and nuclear targeting information.

A hemoglobin A1C immunoassay method not affected by carbamylated hemoglobin

Hemoglobin A1C (HbA1C) methods based on charge separation of Hb species are subject to interference from carbamylated Hb (carb Hb). Carb Hb adducts are formed via interaction of terminal amino groups of HbA with isocyanic acid, after the spontaneous dissociation of urea to cyanate. It is hypothesized that a new immunoassay method, using a monoclonal antibody that recognizes the N-terminus of the Hb beta-chain and its sugar moiety, should be refractory to cross-reactive interference from carb Hb. To test this hypothesis, Hb was carbamylated in vitro and co-migration of carb Hb assessed with HbA1C using an electrophoretic method. Densitometric scans - post sodium cyanate incubation and electrophoretic separation - showed a 5 to 7 fold elevation of the HbA1C peak only, while HbA1C values obtained using immunoassay were unaffected. Also assessed was carbamylation interference in vivo, and a positive proportional bias with the electrophoretic system (Y) was observed compared to the immunoassay system (X) (y = 1.2x - 0.21 percent). Others have shown that carb Hb may cause a clinically significant false elevation in patient HbA1C values, when methods based on charge separation of Hb species are used. It is our conclusion, however, that while carb Hb may play a role, the differences observed in this study are largely due to calibration.

Understanding the sodium pump and its relevance to disease

Na,K-ATPase (sodium pump; EC 3.6.1.37) is present in the membrane of most eukaryotic cells and controls directly or indirectly many essential cellular functions. Regulation of this enzyme (ion transporter) and its individual isoforms is believed to play a key role in the etiology of some pathological processes. The sodium pump is the only known receptor for the cardiac glycosides. However, endogenous ligands structurally similar to digoxin or ouabain may control the activity of this important molecular complex. Here we review the structure and function of Na,K-ATPase, its expression and distribution in tissues, and its interaction with known ligands such as the cardiac glycosides and other suspected endogenous regulators. Also reviewed are various disorders, including cardiovascular, neurological, renal, and metabolic diseases, purported to involve dysfunction of Na,K-ATPase activity. The escalation in knowledge at the molecular level concerning sodium pump function foreshadows application of this knowledge in the clinical laboratory to identify individuals at risk for Na,K-ATPase-associated diseases.

Understanding the sodium pump and its relevance to disease

Na,K-ATPase (sodium pump; EC 3.6.1.37) is present in the membrane of most eukaryotic cells and controls directly or indirectly many essential cellular functions. Regulation of this enzyme (ion transporter) and its individual isoforms is believed to play a key role in the etiology of some pathological processes. The sodium pump is the only known receptor for the cardiac glycosides. However, endogenous ligands structurally similar to digoxin or ouabain may control the activity of this important molecular complex. Here we review the structure and function of Na,K-ATPase, its expression and distribution in tissues, and its interaction with known ligands such as the cardiac glycosides and other suspected endogenous regulators. Also reviewed are various disorders, including cardiovascular, neurological, renal, and metabolic diseases, purported to involve dysfunction of Na,K-ATPase activity. The escalation in knowledge at the molecular level concerning sodium pump function foreshadows application of this knowledge in the clinical laboratory to identify individuals at risk for Na,K-ATPase-associated diseases.

Spontaneous duplication loss and breakage in Caenorhabditis elegans

Duplications in Caenorhabditis elegans spontaneously delete at frequencies ranging from 10(-4) to 10(-5). We have analyzed the structure and mitotic stability of 33 deleted duplications resulting from spontaneous breakage events. (i) Breakage usually occurred at a variety of sites; that is, there were no hot spots for breakage. An exception was the spontaneous breakage of the X chromosome into which hDp14 was inserted. These breaks were close to or at the site of the chromosome I insertion; therefore, the insertion created a type of fragile site. (ii) Spontaneous duplications often had complex structures. In some cases, their structures were most simply resolved by proposing that the progenitor duplication was a ring chromosome with a superimposed inversion. Most of the proposed ring chromosomes were mitotically unstable, suggesting that ring structures increase the frequency of chromosome loss. (iii) Clusters of spontaneous deletion events were rarely observed, suggesting that the majority of spontaneous breakage events probably occurred during meiosis. (iv) A minority of the spontaneous breakage events were associated with linkage to an autosome. Like free duplications of chromosome I, these linked duplications tended to segregate from the X chromosome in males. (v) Three meiotic mutants, him-3, him-6, and him-8, had no effect on somatic loss of the duplications but did reduce the frequency of breakage events. Given the conclusion that chromosome breakage is a meiotic event, these data are consistent with the function of the three meiotic genes being restricted to meiosis.

Two types of sites required for meiotic chromosome pairing in Caenorhabditis elegans

Previous studies have shown that isolated portions of Caenorhabditis elegans chromosomes are not equally capable of meiotic exchange. These results led to the proposal that a homolog recognition region (HRR), defined as the region containing those sequences enabling homologous chromosomes to pair and recombine, is localized near one end of each chromosome. Using translocations and duplications we have localized the chromosome I HRR to the right end. Whereas the other half of chromosome I did not confer any ability for homologs to pair and recombine, deficiencies in this region dominantly suppressed recombination to the middle of the chromosome. These deletions may have disrupted pairing mechanisms that are secondary to and require an HRR. Thus, the processes of pairing and recombination appear to utilize at least two chromosomal elements, the HRR and other pairing sites. For example, terminal sequences from other chromosomes increase the ability of free duplications to recombine with their normal homologs, suggesting that telomere-associated sequences, homologous or nonhomologous, play a role in facilitating meiotic exchange. Recombination can also initiate at internal sites separated from the HRR by chromosome rearrangement, such as deletions of the unc-54 region of chromosome I. When crossing over was suppressed in a region of chromosome I, compensatory increases were observed in other regions. Thus, the presence of the HRR enabled recombination to occur but did not determine the distribution of the crossover events. It seems most likely that there are multiple initiation sites for recombination once homolog recognition has been achieved.

Molecular characterization in the dpy-14 region identifies the adenosylhomocysteine hydrolase gene in Caenorhabditis elegans

The region around dpy-14 on chromosome 1 of Caenorhabditis elegans has been extensively studied genetically, with regard to essential gene organization. This region was one of the first for which cloned DNA was available as a result of restriction fragment length polymorphism mapping. To examine the information content of the cloned DNA in this region, evolutionarily conserved sequences were identified by cross-species hybridization. Ten regions of conservation have been identified and characterized with regard to mRNA abundance and DNA sequence. cDNAs were obtained for seven of these conserved regions and sequence from the cDNAs were used to search the SWISS protein and EMBL nucleotide data banks. Two coding regions shared DNA identifies with existing sequences, the opa repeat family of Drosophila and the S-adenosylhomocysteine hydrolase gene. Of the three for which no corresponding cDNA were found, one corresponds to the snRNA U1-1. The other two did not detect transcripts on Northern analysis and are either conserved, but not coding, or code for low abundance transcripts. The density of conserved coding regions in this study was one per 15 kbp of genomic DNA, three times lower than that reported on chromosome 3 by the genome sequencing project.

Separate information required for nuclear and subnuclear localization: additional complexity in localizing an enzyme shared by mitochondria and nuclei

The TRM1 gene of Saccharomyces cerevisiae codes for a tRNA modification enzyme, N2,N2-dimethylguanosine-specific tRNA methyltransferase (m2(2)Gtase), shared by mitochondria and nuclei. Immunofluorescent staining at the nuclear periphery demonstrates that m2(2)Gtase localizes at or near the nuclear membrane. In determining sequences necessary for targeting the enzyme to nuclei and mitochondria, we found that information required to deliver the enzyme to the nucleus is not sufficient for its correct subnuclear localization. We also determined that mislocalizing the enzyme from the nucleus to the cytoplasm does not destroy its biological function. This change in location was caused by altering a sequence similar to other known nuclear targeting signals (KKSKKKRC), suggesting that shared enzymes are likely to use the same import pathway as proteins that localize only to the nucleus. As with other well-characterized mitochondrial proteins, the mitochondrial import of the shared methyltransferase depends on amino-terminal amino acids, and removal of the first 48 amino acids prevents its import into mitochondria. While this truncated protein is still imported into nuclei, the immunofluorescent staining is uniform throughout rather than at the nuclear periphery, a staining pattern identical to that described for a fusion protein consisting of the first 213 amino acids of m2(2)Gtase in frame with beta-galactosidase. As both of these proteins together contain the entire m2(2)Gtase coding region, the information necessary for association with the nuclear periphery must be more complex than the short linear sequence necessary for nuclear localization.

The meiotic behavior of an inversion in Caenorhabditis elegans

The rearrangement hIn1(I) was isolated as a crossover suppressor for the right end of linkage group (LG) I. By inducing genetic markers on this crossover suppressor and establishing the gene order in the homozygote, hIn1(I) was demonstrated to be the first genetically proven inversion in Caenorhabditis elegans. hIn1(I) extensively suppresses recombination in heterozygotes in the right arm of chromosome I from unc-75 to unc-54. This suppression is associated with enhancement of recombination in other regions of the chromosome. The enhancement observed maintains the normal distribution of events but does not extend to other chromosomes. The genetic distance of chromosome I in inversion heterozygotes approaches 50 map units (m.u.), approximately equal to one chiasma per meiosis. This value is maintained in hIn1(I)/szT1(I;X) heterozygotes indicating that small homologous regions can pair and recombine efficiently. hIn1(I)/hT2(I;III) heterozygotes share no uninverted homologous regions and segregate randomly, suggesting the importance of chiasma formation in proper segregation of chromosomes. The genetic distance of chromosome I in these heterozygotes is less that 1 m.u., indicating that crossing over can be suppressed along an entire chromosome. Since one of our goals was to develop an efficient balancer for the right end of LGI, the effectiveness of hIn1(I) as a balancer was tested by isolating and maintaining lethal mutations. The meiotic behaviour of hIn1(I) is consistent with other genetic and cytogenetic data suggesting the meiotic chromosomes are monocentric. Rare recombinants bearing duplications and deficiencies of chromosome I were recovered from hIn1(I) heterozygotes, leading to the proposal the inversion was paracentric.

Genetic and molecular analysis of the dpy-14 region in Caenorhabditis elegans

Essential genes have been identified in the 1.5 map unit (m.u.) dpy-14-unc-29 region of chromosome 1 in Caenorhabditis elegans. Previous work defined nine genes with visible mutant phenotypes and nine genes with lethal mutant phenotypes. In this study, we have identified an additional 28 essential genes with 97 lethal mutations. The mutations were mapped using eleven duplication breakpoints, eight deficiencies and three-factor recombination experiments. Genes required for the early stages of development were common, with 24 of the 37 essential genes having mutant phenotypes arresting at an early larval stage. Most mutants of a gene have the same time of arrest; only four of the 20 essential genes with multiple alleles have alleles with different phenotypes. From the analysis of complementing alleles of let-389, alleles with the same time-of-arrest phenotype were classified as either hypomorphic or amorphic. Mutants of let-605, let-534 and unc-37 have both uncoordinated and lethal phenotypes, suggesting that these genes are required for the coordination of movement and for viability. The physical and genetic maps in the dpy-14 region were linked by positioning two N2/BO polymorphisms with respect to duplications in the region, and by localizing the right breakpoint of the deficiency hDf8 on the physical map. Using cross-species hybridization to C. briggsae, ten regions of homology have been identified, eight of which are known to be coding regions, based on Northern analysis and/or the isolation of cDNA clones.

Mutations in the bli-4 (I) locus of Caenorhabditis elegans disrupt both adult cuticle and early larval development

The bli-4 (I) gene of Caenorhabditis elegans had been previously defined by a single recessive mutation, e937, which disrupts the structure of adult-stage cuticle causing the formation of fluid-filled separations of the cuticle layers, or blisters. We report the identification of 11 new alleles of bli-4, all early larval lethals, including an allele induced by transposon mutagenesis. Nine of the lethal alleles failed to complement the blistered phenotype of e937; two alleles, s90 and h754, complement e937. The complementing alleles arrested development somewhat later than the noncomplementing alleles, which blocked just prior to hatching. We conclude that bli-4 is a complex locus with an essential function late in embryogenesis. We investigated the blistered phenotype of e937 through interactions with other mutations that alter worm morphology or cuticle structure. Recessive and dominant epistasis of several dumpy mutations over the blistered phenotype was observed. Using two heterochronic mutations that alter the developmental stage at which adult cuticle is expressed, we observed that adult worms that lack an adult-stage cuticle could not express blisters. However, late larval worms that expressed the adult cuticle did not express blisters either. It seems likely that the presence of the adult cuticle is necessary, but not sufficient, for blister expression. Blistering resulting from e937 is more severe in trans to null alleles, indicating that e937 is hypomorphic. We postulate that the adult-specific blistering is due to an altered or reduced function of bli-4 gene product in the adult cuticle.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening potential blood donors at risk for human immunodeficiency virus

Even though all blood donated for transfusion is tested for the presence of human immunodeficiency virus (HIV) antibodies, there exists a period of time after infection by the virus before these antibodies can be detected. Blood donated during this window period is capable of transmitting the virus. Therefore, the blood of persons who are at risk for acquired immune deficiency syndrome (AIDS) should not enter the blood supply. Over a period of 4 months, 6573 potential blood donors who entered fixed and mobile blood collection sites in two cities were exposed to alternative interventions the aim of which was to exclude persons at risk for AIDS. We compared the interventions to one another and to existing materials in terms of the numbers of at-risk persons who did or did not donate for transfusion, the amount of attention paid to the materials, the scores on a comprehension test, and the self-reports by the subjects of attitudes towards the various interventions. At-risk donors who were asked direct AIDS risk behavior questions in addition to the current health history questions were more likely to be screened out than those who underwent alternative health history interviews (p less than 0.01). Potential donors paid more attention to the experimental brochures than to the experimental video or current materials (p less than 0.05). Comprehension scores were better for the new brochure and the video than for the current brochure (p less than 0.05). Donors were not offended by the experimental interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolutionarily conserved regions in Caenorhabditis transposable elements deduced by sequence comparison

In this paper we present the sequence of an intact Caenorhabditis briggsae transposable element, Tcb2. Tcb2 is 1606 base pairs in length and contains 80 base pair imperfect terminal repeats and a single open reading frame. We have identified blocks of T-rich repeats in the regions 150-200 and 1421-1476 of this element which are conserved in the Caenorhabditis elegans element Tc1. The sequence conservation of these regions in elements from different Caenorhabditis species suggests that they are of functional importance. A single open reading frame corresponding to the major open reading frame of Tc1 is conserved among Tc1, Tcb1, and Tcb2. Comparison of the first 550 nucleotides of the sequence among the three elements has allowed the evaluation of a model proposing an extension of the major open reading frame. Our data support the suggestion that Tc1 is capable of producing a 335 amino acid protein. A comparison of the sequence coding for the amino and carboxy termini of the 273 amino acid transposase from Caenorhabditis Tc1-like elements and Drosophila HB1 showed different amounts of divergence for each of these regions, indicating that the two functional domains have undergone different amounts of selection. Our data are not compatible with the proposal that Tc1-related sequences have been acquired via horizontal transmission. The divergence of Tc1 from the two C. briggsae elements, Tcb1 and Tcb2, indicated that all three elements have been diverging from each other for approximately the same amount of time as the genomes of the two species.

Essential genes in the hDf6 region of chromosome I in Caenorhabditis elegans

In this paper we describe the analysis of essential genes in the hDf6 region of chromosome I of Caenorhabditis elegans. Nineteen complementation groups have been identified which are required for the growth, survival or fertility of the organism (essential genes). Since ten of these genes were represented by more than one allele, a Poisson calculation predicts a minimum estimate of 25 essential genes in hDf6. The most mutable gene in this region was let-354 with seventeen alleles. An average mutation rate of 5 x 10(-5) mutations/gene/chromosome screened was calculated for an ethyl methanesulfonate dose of 15 mM. Mutations were recovered by screening for lethal mutations using the duplication sDp2 for recovery. Our analysis shows that duplications are very effective for maintenance and mapping of large numbers of lethal mutations. Approximately 600 lethal mutations were mapped in order to identify the 54 that are in the deficiency hDf6. The hDf6 region appears to have a lower proportion of early arresting mutations than other comparably sized regions of the genome.

Sex-related differences in crossing over in Caenorhabditis elegans

In the nematode Caenorhabditis elegans, hermaphrodite recombination has been characterized and is the basis of the genetic map used in this organism. In this study we have examined male recombination on linkage group I and have found it to be approximately one-third less than that observed in the hermaphrodite. This decrease was interval-dependent and nonuniform. We observed less recombination in the male in 5 out of 6 intervals examined, and no observable difference in one interval on the right end of LG I. Hermaphrodite recombination frequencies are the result of recombination in two germlines; oocyte and hermaphrodite spermatocytes. We have measured recombination in the oocyte and have found it to be approximately twofold lower than that calculated for hermaphrodite spermatocytes and not significantly different from the male spermatocyte frequency. Thus, recombination frequencies appear to be a function of gonad physiology rather than the sex of the germline. Evidence from experiments examining the effect of karyotype on recombination in males sexually transformed by the her-1 mutation into XO hermaphrodites (normally XX), suggests the sexual phenotype rather than genotype determines the recombination frequency characteristic of a particular sex. Hermaphrodite recombination is known to be affected by temperature, maternal age, and the rec-1 mutation. We have examined the effect of these parameters on recombination in the male and have found male recombination frequency increased with elevated temperatures and in the presence of Rec-1, and decreased with paternal age.

Tc1 transposition and mutator activity in a Bristol strain of Caenorhabditis elegans

In most strains of Caenorhabditis elegans with a low copy number of Tc1 transposable elements, germline transposition is rare or undetectable. We have observed low-level Tc1 transposition in the genome of the C. elegans var. Bristol strain KR579 (unc-13[e51]) resulting in an increase in Tc1 copy number and subsequent mutator activity. Examination of genomic blots from KR579 and KR579-derived strains revealed that more Tc1-hybridizing bands were present than in other Bristol strains. A novel Tc1-hybridizing fragment was cloned from a KR579-derived strain. Unique sequence DNA flanking the Tc1 element identified a 1.6 kb restriction fragment length difference between the KR579 and N2 strains consistent with a Tc1 insertion at a new genomic site. The site of insertion of this Tc1 was sequenced and is similar to the published Tc1 insertion site consensus sequence. Several isolates of KR579 were established and maintained on plates for a period of 3 years in order to determine if Tc1 copy number would continue to increase. In one isolate, KR1787, a further increase in Tc1 copy number was observed. Examination of the KR1787 strain has shown that it also exhibits mutator activity as assayed by the spontaneous mutation frequency at the unc-22 (twitcher) locus. The KR579 strain differs from most low copy number strains in that it exhibits low-level transposition which has developed into mutator activity.