Genomic analyses in Cornelia de Lange Syndrome and related diagnoses: Novel candidate genes, genotype-phenotype correlations and common mechanisms

Cornelia de Lange Syndrome (CdLS) is a rare, dominantly inherited multisystem developmental disorder characterized by highly variable manifestations of growth and developmental delays, upper limb involvement, hypertrichosis, cardiac, gastrointestinal, craniofacial, and other systemic features. Pathogenic variants in genes encoding cohesin complex structural subunits and regulatory proteins (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major pathogenic contributors to CdLS. Heterozygous or hemizygous variants in the genes encoding these five proteins have been found to be contributory to CdLS, with variants in NIPBL accounting for the majority (>60%) of cases, and the only gene identified to date that results in the severe or classic form of CdLS when mutated. Pathogenic variants in cohesin genes other than NIPBL tend to result in a less severe phenotype. Causative variants in additional genes, such as ANKRD11, EP300, AFF4, TAF1, and BRD4, can cause a CdLS-like phenotype. The common role that these genes, and others, play as critical regulators of developmental transcriptional control has led to the conditions they cause being referred to as disorders of transcriptional regulation (or "DTRs"). Here, we report the results of a comprehensive molecular analysis in a cohort of 716 probands with typical and atypical CdLS in order to delineate the genetic contribution of causative variants in cohesin complex genes as well as novel candidate genes, genotype-phenotype correlations, and the utility of genome sequencing in understanding the mutational landscape in this population.

Genetic and cytological analyses reveal the recombination landscape of a partially differentiated plant sex chromosome in kiwifruit

BACKGROUND

Angiosperm sex chromosomes, where present, are generally recently evolved. The key step in initiating the development of sex chromosomes from autosomes is the establishment of a sex-determining locus within a region of non-recombination. To better understand early sex chromosome evolution, it is important to determine the process by which recombination is suppressed around the sex determining genes. We have used the dioecious angiosperm kiwifruit Actinidia chinensis var. chinensis, which has an active-Y sex chromosome system, to study recombination rates around the sex locus, to better understand key events in the development of sex chromosomes.

RESULTS

We have confirmed the sex-determining region (SDR) in A. chinensis var. chinensis, using a combination of high density genetic mapping and fluorescent in situ hybridisation (FISH) of Bacterial Artificial Chromosomes (BACs) linked to the sex markers onto pachytene chromosomes. The SDR is a subtelomeric non-recombining region adjacent to the nucleolar organiser region (NOR). A region of restricted recombination of around 6 Mbp in size in both male and female maps spans the SDR and covers around a third of chromosome 25.

CONCLUSIONS

As recombination is suppressed over a similar region between X chromosomes and between and X and Y chromosomes, we propose that recombination is suppressed in this region because of the proximity of the NOR and the centromere, with both the NOR and centromere suppressing recombination, and this predates suppressed recombination due to differences between X and Y chromosomes. Such regions of suppressed recombination in the genome provide an opportunity for the evolution of sex chromosomes, if a sex-determining locus develops there or translocates into this region.

Outcomes of clinical examination and genetic testing of 500 individuals with hearing loss evaluated through a genetics of hearing loss clinic

Hearing loss (HL) occurs in approximately 2 out of every 1,000 births and is genetic in origin in approximately 50% of cases. This high incidence coupled with the increasing number of genes implicated in HL and the trend toward universal newborn screening led to the establishment of the Genetics of Hearing Loss Clinic at The Children's Hospital of Philadelphia to manage the diagnosis, genetic screening, and counseling of families with an affected child. To date 500 individuals have been evaluated from 1999 to 2004. To determine the cause of their HL and screen for syndromic forms of HL, individuals were offered a panel of tests. Depending on the type and severity of the HL, recommendations included GJB2 mutation analysis, renal and thyroid function studies, a CT scan of the temporal bones, an ophthalmology evaluation, an EKG, and, at times, additional genetic tests. Of the 500 patients evaluated 70 (14%) had a syndromic etiology for their HL. Twenty-eight different syndromic etiologies were identified. Enlarged vestibular aqueducts (EVAs) and/or Mondini malformations were seen in 18% of individuals with HL who had a CT or MRI of the temporal bones. Genetic testing of the GJB2 gene was completed for 310 of the 377 patients with bilateral sensorineural HL (82.2%). Nineteen different variants were identified in the GJB2 gene. Through GJB2 mutational analysis, clinical examination, and laboratory testing, a definitive etiologic diagnosis was established in 110/500 (22%) of patients.

Novel, complex interruptions of the GAA repeat in small, expanded alleles of two affected siblings with late-onset Friedreich ataxia

Friedreich ataxia (FA) is an autosomal recessive disorder associated with expanded GAA repeats in intron 1 of the FRDA gene. Two siblings presented with a mild form of FA at >60 years of age. Both had a large expansion (>600 repeats) and a small expansion (120 repeats) by long-range PCR. Sequence analysis of the small allele revealed multiple, complex interruptions in the GAA repeat. These 2 patients presented later than predicted from their allele size alone, when compared with a large cohort of FA patients. Accounting for the interruptions in the GAA repeat, though, did not make the age of onset consistent with that noted in other patients. Three additional patients with late onset FA and small expanded alleles also exhibited interrupted GAA repeats that were not associated with inappropriately late onset. Our observations suggest that interrupted GAA repeats do not clearly impact the age of onset in FA.

The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases

Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.

Additional clinical manifestations in children with sensorineural hearing loss and biallelic GJB2 mutations: who should be offered GJB2 testing?

Sensorineural hearing loss (SNHL), the most common sensory impairment noted at birth, occurs in 3 out of every 1,000 births live births. At least half of congenital SNHL is genetic in origin, with nonsyndromic, or isolated hearing loss, accounting for approximately 70% of the total genetic causes. Syndromic hearing loss (hearing loss associated with other clinical findings) makes up the remaining 30%. Worldwide, mutations in the gap junction beta 2 (GJB2) gene, encoding the connexin 26 (Cx26) protein, are responsible for approximately 30% of all cases of childhood SNHL. GJB2 mutations have been primarily associated with nonsyndromic forms of bilateral SNHL although rare syndromic forms involving dermatologic manifestations have also been reported. In general, unless skin findings are present, children with bilateral SNHL and other structural or developmental abnormalities are not generally thought of as candidates for GJB2 testing. We evaluated 163 individuals with biallelic GJB2 mutations and SNHL for the presence of other clinical findings. Twenty-nine of the 163 (18%) were found to have structural and/or developmental abnormalities in addition to the SNHL and four subjects had diagnoses that were felt to account for their hearing loss prior to being screened for GJB2 mutations. Although the GJB2 mutations are likely not responsible for these additional clinical manifestations, this study underscores the importance of considering GJB2 mutational analysis in individuals with more than just isolated SNHL given the high prevalence of GJB2-related hearing loss.

Outcomes in 2748 patients referred to a colorectal two-week rule clinic

OBJECTIVE

To assess the 3-year outcomes of a nurse-led, one-stop, 2-week rule (TWR) clinic for suspected colorectal cancer (CRC) in a large teaching hospital.

METHOD

Data were collected prospectively from January 2002 to December 2004. In total, 2748 patients were seen over the 3-year period. The ratio of male:female subjects was 1190:1558 (43%:57%). Median age at presentation was 66 years (range 17-96).

RESULTS

A total of 1363 (49.6%) nonconforming referrals were made; 1300 patients (47.3%) underwent flexible sigmoidoscopy during their initial assessment in clinic; 1439 patients (52.4%) underwent a barium enema during the course of their investigation; 2503 patients (91.1%) were seen within 14 working days. The median overall wait for the initial clinic appointment was 10 days. The annual number of patients seen was similar over the 3-year period. A total of 174 cancers (6.3%) were identified which accounted for 36.4% of all CRCs diagnosed during the study period. Nineteen cancers presented in the nonconforming group (1.6% of all non-conforming patients). Rectal tumours accounted for 59.8% (n = 104) of all cancers diagnosed while right-sided tumours accounted for only 10.9% (n = 19). Advanced tumours accounted for 73.0% (n = 127) of the total; 133 (76.4%) cancer patients underwent some form of surgical intervention.

CONCLUSION

A specialist nurse-led, one-stop TWR clinic for suspected colorectal cancer is sustainable and can be run successfully with over 90% of referrals seen within the targeted time period. The proportion of non-conforming referrals was high and a large number of advanced and unstaged tumours was observed. Low numbers of proximal tumours were detected.

Ophthalmologic findings in Cornelia de Lange syndrome: a genotype-phenotype correlation study

OBJECTIVE

To evaluate individuals with Cornelia de Lange syndrome previously screened for mutations in the NIPBL gene for genotype-phenotype correlations with regard to severity of ophthalmologic findings.

METHODS

Fifty-four patients with Cornelia de Lange syndrome (26 mutation positive and 28 mutation negative) with varying extent and severity of ophthalmologic findings participated in the study. We conducted a retrospective analysis of ophthalmologic data obtained through survey responses and medical records. The severity of nasolacrimal duct obstruction, myopia, ptosis, and strabismus was classified. The severity of eye findings was compared relative to the presence vs the absence of mutations in the coding region of NIPBL and relative to mutations predicted to result in a truncated protein (nonsense and frameshift mutations) vs missense mutations. Fisher exact test was used to determine the significance of these correlations.

RESULTS

A trend toward increased ptosis severity was found among individuals with truncating (nonsense and frameshift) mutations compared with individuals with missense mutations (P = .07).

CONCLUSION

NIPBL may be directly involved in ptosis pathogenesis.

CLINICAL RELEVANCE

Elucidating the pathogenetic mechanisms of ophthalmologic morbidities in patients with de Lange syndrome may lead to more effective treatment.

Tea tree oil: in vitro efficacy in otitis externa

Objective: The purpose of this study was to determine the susceptibility of organisms causing otitis externa (OE) to the essential oil of Melaleuca alternifolia, or tea tree oil (TTO).

Methods: Fifty-seven swabs were taken from the ears of 52 patients with OE for culture and sensitivity. A broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of TTO for each organism.

Results: In 51 per cent of the swabs taken, pathogenic organisms were cultured. Of these cultures 71 per cent, both bacteria and yeast, were susceptible to TTO 2 per cent or less. The only organism showing resistance to TTO was Pseudomonas aeruginosa; however 25 per cent of these bacteria were sensitive.

Conclusion: Tea tree oil may have a role to play in the treatment of OE. However, more work needs to be done to enhance the anti-pseudomonal effect and to assess ototoxicity.

Precocious sister chromatid separation (PSCS) in Cornelia de Lange syndrome

The Cornelia de Lange syndrome (CdLS) (OMIM# 122470) is a dominantly inherited multisystem developmental disorder. The phenotype consists of characteristic facial features, hirsutism, abnormalities of the upper extremities ranging from subtle changes in the phalanges and metacarpal bones to oligodactyly and phocomelia, gastroesophageal dysfunction, growth retardation, and neurodevelopmental delay. Prevalence is estimated to be as high as 1 in 10,000. Recently, mutations in NIPBL were identified in sporadic and familial CdLS cases. To date, mutations in this gene have been identified in over 45% of individuals with CdLS. NIPBL is the human homolog of the Drosophila Nipped-B gene. Although its function in mammalian systems has not yet been elucidated, sequence homologs of Nipped-B in yeast (Scc2 and Mis4) are required for sister chromatid cohesion during mitosis, and a similar role was recently demonstrated for Nipped-B in Drosophila. In order to evaluate NIPBL role in sister chromatid cohesion in humans, metaphase spreads on 90 probands (40 NIPBL mutation positive and 50 NIPBL mutation negative) with CdLS were evaluated for evidence of precocious sister chromatid separation (PSCS). We screened 50 metaphases from each proband and found evidence of PSCS in 41% (compared to 9% in control samples). These studies indicate that NIPBL may play a role in sister chromatid cohesion in humans as has been reported for its homologs in Drosophila and yeast.

Factors influencing discharge location following high lesion spinal cord injury rehabilitation in British Columbia, Canada

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

To identify and describe factors that influence discharge location -- extended care unit (nursing home) or other (private home, group home, or acute care) -- following rehabilitation for individuals with a new high lesion spinal cord injury (SCI) (C1-C4) in British Columbia, Canada.

SETTING

GF Strong Rehabilitation Centre, Vancouver, British Columbia, Canada.

METHODS

Eligible clients were adults admitted to the GF Strong Rehabilitation Centre Spinal Cord Program between 1994 and 2003, with a new C1-4 lesion (traumatic or nontraumatic), and an ASIA score of A-C at time of discharge. Medical charts of 52 individuals were reviewed and data regarding individual characteristics, health-related characteristics, personal context, hospitalization factors, health resources, and other contextual factors were extracted.

RESULTS

In total, 40% of clients were discharged to extended care units post rehabilitation. Seven variables were associated at a univariate level: age, employment at the time of injury, pre-existing medical conditions, social support, preinjury living situation, and insurance (worker's compensation or motor vehicle) or private funding for equipment. Four variables were associated at the multivariate level: age, preinjury living situation, and insurance or private funding for equipment.

CONCLUSION

A range of individual, health-related, family and social policy variables influence discharge location following rehabilitation for high lesion SCI in British Columbia. The unique combination of variables presented by each individual should be considered by the rehabilitation team in the discharge planning process.

Subunit-specific regulation of NMDA receptor endocytosis

At excitatory synapses, both NMDA and AMPA receptors are localized to the postsynaptic density (PSD). However, unlike AMPA receptors, synaptic NMDA receptors are stable components of the PSD. Even so, surface-expressed NMDA receptors undergo endocytosis, which is more robust early in development and declines during synaptic development. We investigated the subunit-specific contributions to NMDA receptor endocytosis, specifically defining the endocytic motifs and endocytic pathways preferred by the NR2A and NR2B subunits. We find that NR2A and NR2B have distinct endocytic motifs encoded in their distal C termini and that these interact with clathrin adaptor complexes with differing affinities. We also find that NR2A and NR2B sort into different intracellular pathways after endocytosis, with NR2B preferentially trafficking through recycling endosomes. In mature cultures, we find that NR2B undergoes more robust endocytosis than NR2A, consistent with previous studies showing that NR2A is more highly expressed at stable synaptic sites. Our findings demonstrate fundamental differences between NR2A and NR2B that help clarify developmental changes in NMDA receptor trafficking and surface expression.

NIPBL mutational analysis in 120 individuals with Cornelia de Lange syndrome and evaluation of genotype-phenotype correlations

The Cornelia de Lange syndrome (CdLS) is a multisystem developmental disorder characterized by facial dysmorphia, upper-extremity malformations, hirsutism, cardiac defects, growth and cognitive retardation, and gastrointestinal abnormalities. Both missense and protein-truncating mutations in NIPBL, the human homolog of the Drosophila melanogaster Nipped-B gene, have recently been reported to cause CdLS. The function of NIPBL in mammals is unknown. The Drosophila Nipped-B protein facilitates long-range enhancer-promoter interactions and plays a role in Notch signaling and other developmental pathways, as well as being involved in mitotic sister-chromatid cohesion. We report the spectrum and distribution of NIPBL mutations in a large well-characterized cohort of individuals with CdLS. Mutations were found in 56 (47%) of 120 unrelated individuals with sporadic or familial CdLS. Statistically significant phenotypic differences between mutation-positive and mutation-negative individuals were identified. Analysis also suggested a trend toward a milder phenotype in individuals with missense mutations than in those with other types of mutations.

Cornelia de Lange syndrome is caused by mutations in NIPBL, the human homolog of Drosophila melanogaster Nipped-B

Cornelia de Lange syndrome (CdLS; OMIM 122470) is a dominantly inherited multisystem developmental disorder characterized by growth and cognitive retardation; abnormalities of the upper limbs; gastroesophageal dysfunction; cardiac, ophthalmologic and genitourinary anomalies; hirsutism; and characteristic facial features. Genital anomalies, pyloric stenosis, congenital diaphragmatic hernias, cardiac septal defects, hearing loss and autistic and self-injurious tendencies also frequently occur. Prevalence is estimated to be as high as 1 in 10,000 (ref. 4). We carried out genome-wide linkage exclusion analysis in 12 families with CdLS and identified four candidate regions, of which chromosome 5p13.1 gave the highest multipoint lod score of 2.7. This information, together with the previous identification of a child with CdLS with a de novo t(5;13)(p13.1;q12.1) translocation, allowed delineation of a 1.1-Mb critical region on chromosome 5 for the gene mutated in CdLS. We identified mutations in one gene in this region, which we named NIPBL, in four sporadic and two familial cases of CdLS. We characterized the genomic structure of NIPBL and found that it is widely expressed in fetal and adult tissues. The fly homolog of NIPBL, Nipped-B, facilitates enhancer-promoter communication and regulates Notch signaling and other developmental pathways in Drosophila melanogaster.

Trafficking and surface expression of the glutamate receptor subunit, KA2

Kainate receptors are a class of ionotropic glutamate receptors that are widely expressed in the mammalian brain, yet little is known about their physiological role or the mechanisms by which they are regulated. Kainate receptors are composed of multiple subunits (GluR5-7; KA1-2), which can combine to form homomeric or heteromeric channels. While the kainate receptor subunit KA2 can combine with GluR5-7 to form heteromeric channels, it does not form functional homomeric channels when expressed alone. In an attempt to identify the molecular mechanisms for this, we have characterized the trafficking and surface expression of KA2. We find that KA2 alone does not traffic to the plasma membrane and is retained in the endoplasmic reticulum (ER). In contrast, co-expression with GluR6 disrupts ER-retention of KA2 and allows plasma membrane expression. Using a chimeric reporter protein we have identified an ER-retention motif within the KA2 cytosolic domain. Recent studies have identified a consensus ER-retention motif (RRR) that is contained within both the NMDA receptor NR1 subunit and K(+) channels. While KA2 contains a similar stretch of amino acids within its C-terminus (RRRRR), unlike the NR1 motif, disruption of this motif with alternating glutamic acid residues does not disrupt ER-retention of KA2, suggesting a unique mechanism regulating KA2 surface expression.

Differential binding of the AP-2 adaptor complex and PSD-95 to the C-terminus of the NMDA receptor subunit NR2B regulates surface expression

NMDA receptor expression on the plasma membrane and at synaptic sites is tightly regulated. We have recently shown that the NMDA receptor subunit NR2B has an endocytic motif contained within its C-terminus. We now identify this motif as a consensus tyrosine-based motif (YEKL) and demonstrate that this sequence binds directly to the medium chain of the AP-2 adaptor, a protein complex that links internalized proteins to clathrin. Although the AP-2 binding site on NR2B is adjacent to the PSD-95 binding site, it is distinct, as mutation of tyrosine 1472 of the endocytic motif disrupts AP-2 binding but not binding to PSD-95. Internalization assays reveal that like PSD-95, both SAP97 and PSD-93 inhibit NR2B-mediated endocytosis. Furthermore, we find that co-expression of a PSD-95 mutant that is unable to cluster NMDA receptors also inhibits NR2B-mediated endocytosis. Together, these data demonstrate that AP-2 and PSD-95 bind to unique sites on the C-terminus of NR2B and have antagonistic functional consequences that are independent of the ability of the PSD-95 to cluster receptors on the plasma membrane.

Assessing health-related quality of life following myocardial infarction: is the SF-12 useful?

We report on the responsiveness of the SF-12 to changes in quality of life following acute myocardial infarction. Scores at 1, 6, 12, and 24 weeks postdischarge were compared with pre-MI health. Statistically significant differences and standardized response means were examined. Results were compared with the SF-36 subscales and previous reports. Respondents (n = 65) reported the expected poorer physical health at every follow-up, while expected changes in emotional health were observed at 6 but not 24 weeks. Comparison with the SF-36 subscales showed that although the SF-12 reflected the expected pattern of physical health, the summary score obscured an important association between perceptions of general health and participation in usual activities. This information is relevant for developing and evaluating rehabilitation interventions and self-managed recovery following MI. The SF-12 scores obscure important distinctions between quality of life domains, and are therefore not recommended for use following acute MI.

Cholesterol and other lipids predict coronary heart disease and ischaemic stroke in the elderly, but only in those below 70 years

The prediction of coronary heart disease (CHD) and stroke by total and low density lipoprotein (LDL) cholesterol in older persons remains problematical. This study tests the hypothesis that cholesterol and other risk factors may be differentially predictive of CHD and ischaemic stroke in older persons when they are segregated into different age groups. CHD and ischaemic stroke outcomes were recorded during 129 months follow-up in a cohort of 2805 men and women of 60 years and older. There were 899 CHD events (32/100) and 326 stroke events (12/100). Using Cox proportional hazards, outcomes were modelled for the total cohort and for age groups 60-69, 70-79, and 80+ years. Total cholesterol, LDL cholesterol, serum apo-B, total cholesterol/high density lipoprotein (HDL) cholesterol and apo-B/apo-A1 were significant predictors of CHD in the total cohort, but significant only in the sub-group of 60-69 years. The respective hazard ratios (CI 95%) were 1.21 (1.09-1.35), 1.21 (1.09-1.35), 1.25 (1.13-1.39), 1.25 (1.14-1.37) and 1.21 (1.10-1.38). Similar findings were applicable with respect to ischaemic stroke in the age group of 60-69 years. Total cholesterol predicted CHD in men above a threshold value of 7.06 mmol/l and in women above 7.8 mmol/l, but with stroke the prediction was incremental. Other risk factors such as HDL cholesterol, triglycerides, lipoprotein(a), diabetes, hypertension and smoking predicted CHD, although only HDL and hypertension similarly predicted ischaemic stroke. The findings support a case for cholesterol testing in older subjects up to 70 years, in whom there is ancillary evidence of CHD and stroke prevention through treatment designed to reduce LDL cholesterol.

Synapse-associated protein 97 selectively associates with a subset of AMPA receptors early in their biosynthetic pathway

The regulation of AMPA receptors at the postsynaptic membrane is a fundamental component of synaptic plasticity. In the hippocampus, the induction of long-term potentiation increases the delivery of GluR1, a major AMPA receptor subunit in hippocampal pyramidal neurons, to the synaptic plasma membrane through a mechanism that requires the PDZ binding domain of GluR1. Synapse-associated protein 97 (SAP97), a member of the membrane-associated guanylate kinase family, is believed to associate with AMPA receptors (AMPARs) containing the GluR1 subunit, but the functional significance of these interactions is unclear. We investigated the interaction of GluR1 with SAP97, the only PDZ protein known to interact with GluR1. We find that interactions involving SAP97 and GluR1 occur early in the secretory pathway, while the receptors are in the endoplasmic reticulum or cis-Golgi. In contrast, few synaptic receptors associate with SAP97, suggesting that SAP97 dissociates from the receptor complex at the plasma membrane. We also show that internalization of GluR1, as triggered by NMDAR activation, does not require SAP97. These results implicate GluR1-SAP97 interactions in mechanisms underlying AMPA receptor targeting.

Molecular determinants of NMDA receptor internalization

Although synaptic AMPA receptors have been shown to rapidly internalize, synaptic NMDA receptors are reported to be static. It is not certain whether NMDA receptor stability at synaptic sites is an inherent property of the receptor, or is due to stabilization by scaffolding proteins. In this study, we demonstrate that NMDA receptors are internalized in both heterologous cells and neurons, and we define an internalization motif, YEKL, on the distal C-terminus of NR2B. In addition, we show that the synaptic protein PSD-95 inhibits NR2B-mediated internalization, and that deletion of the PDZ-binding domain of NR2B increases internalization in neurons. This suggests an involvement for PSD-95 in NMDA receptor regulation and an explanation for NMDA receptor stability at synaptic sites.

A prospective randomized clinical trial to evaluate methods of postoperative care of hypospadias

PURPOSE

Hypospadias repair is a common operation performed by pediatric urologists. Perhaps the greatest variable and source of controversy of postoperative care is the surgical dressing. We hypothesized that using no dressing would achieve surgically comparable results to those traditionally achieved by a postoperative dressing and it would also simplify postoperative parent delivered home care. Accordingly we designed a prospective randomized clinical trial to compare surgical outcome and postoperative care after hypospadias repair in boys with no dressing and those who received 1 of the 2 most common types of dressing.

MATERIALS AND METHODS

In a 12-month period 120 boys with an average age of 2.2 years underwent primary 1-stage hypospadias repair at a single center with 4 participating surgeons. Repair was performed in 60 boys with proximal and 60 with distal hypospadias on an outpatient basis. Ethics and Internal Review Board approval, and informed consent were obtained. Boys were then prospectively randomized to receive no dressing, an adhesive biomembrane dressing or a compressive wrap dressing. Comprehensive instructions on postoperative care were distributed to all families and a questionnaire was distributed to the parents at the initial followup. Surgical outcome was evaluated and questionnaire responses were analyzed. Fisher's exact test was done to test the significance of differences in surgical outcomes and questionnaire responses.

RESULTS

A total of 117 boys completed the prospective randomized trial. Surgical staff withdrew 3 cases from randomized selection to place a dressing for postoperative hemostasis. We obtained 101 questionnaires for response analysis. The type or absence of the dressing did not correlate with the need for repeat procedures, urethrocutaneous fistula, or meatal stenosis or regression. Analysis revealed less narcotic use in the no dressing group and fewer telephone calls to the urology nurse, or on-call resident and/or fellow. These findings were statistically significant. In addition, there were more unscheduled visits to the urology clinic, emergency room or primary physician office by boys with than without a dressing. Furthermore, 29% of the parents were not psychologically prepared to remove the dressing and 12% were so reluctant that the dressing was removed at the urology outpatient clinic.

CONCLUSIONS

The surgical outcome and rate of adverse events or complications were not compromised without a postoperative dressing. An absent dressing simplified postoperative ambulatory parent delivered home care. We recommend that dressings should be omitted from routine use after hypospadias repair.

PDZ domain suppression of an ER retention signal in NMDA receptor NR1 splice variants

The NMDA receptor NR1 subunit has four splice variants that differ in their C-terminal, cytoplasmic domain. We investigated the contribution of the C-terminal cassettes, C0, C1, C2, and C2', to trafficking of NR1 in heterologous cells and neurons. We identified an ER retention signal (RRR) in the C1 cassette of NR1, which is similar to the RXR motif in ATP-sensitive K(+) channels (Zerangue et al., 1999). We found that surface expression of NR1-3, which contains C1, is due to a site on the C2' cassette, which includes the terminal 4 amino acid PDZ-interacting domain. This site suppresses ER retention of the C1 cassette and leads to surface expression. These findings suggest a role for PDZ proteins in facilitating the transition of receptors from an intracellular pool to the surface of the neuron.

Moderate alcohol intake is associated with survival in the elderly: the Dubbo Study

OBJECTIVE

To examine the relationship between alcohol intake and survival in elderly people.

DESIGN AND SETTING

A prospective study over 116 months of non-institutionalised subjects living in Dubbo, a rural town (population, 34,000) in New South Wales.

PARTICIPANTS

1235 men and 1570 women aged 60 years and over who were first examined in 1988-89.

MAIN OUTCOME MEASURES

All-causes mortality; gross cost of alcohol per life-year gained.

RESULTS

Death occurred in 450 men and 392 women. Intake of alcohol was generally moderate (i.e., less than 14 drinks/week). Any intake of alcohol was associated with reduced mortality in men up to 75 years and in women over 64 years. In a proportional hazards model, the hazard ratio for mortality in men taking any alcohol was 0.63 (95% CI, 0.47-0.84) and in women was 0.75 (95% CI, 0.60-0.94). Cardiovascular deaths in men were reduced from 20/100 (95% CI, 14-26) to 11/100 (95% CI, 9-13) and in women from 16/100 (95% CI, 13-19) to 8/100 (95% CI, 6-10). The reduction in mortality occurred in men and women taking only 1-7 drinks/week--hazard ratios, 0.68 (95% CI, 0.49-0.94) and 0.78 (95% CI, 0.61-0.99), respectively, with a similar protective effect from intake of beer or other forms of alcohol. After almost 10 years' follow-up, men taking any alcohol lived on average 7.6 months longer, and women on average 2.7 months longer, compared with non-drinkers. The gross cost for alcohol per life-year gained if consuming 1-7 drinks/week was $5700 in men, and $19,000 in women.

CONCLUSIONS

Moderate alcohol intake in the elderly appears to be associated with significantly longer survival in men 60-74 years and in all elderly women.

Healthy ageing is associated with reduced and delayed disability

OBJECTIVE

to identify subgroups within the population with reduced or delayed disability during healthy ageing.

DESIGN

a longitudinal, community-based study.

SETTING

Dubbo, New South Wales, Australia.

PARTICIPANTS

2805 men and women 60 years and older, first examined in 1988-89.

OUTCOME MEASURES

activities of daily living assessed serially every 2 years over 8 years (scored in the range 0-6, least to most impaired); scores related to subsequent hospital admissions and to demographic, clinical and psychosocial characteristics at baseline.

RESULTS

1973 men and women provided complete follow-up data. Mean disability score at entry was low at 0.18 and increased to 0.69 by the final survey. Those having three or more hospital admissions (40% of the sample) had minimum disability (disability score approximately 0.3) around 5 years earlier than those with fewer admissions. Those with dementia or other mental illness had the most severe disability (mean disability scores of 3.15 and 2.13 respectively), but their numbers were very small. Those with a stroke or respiratory illness were more numerous and they had major physical disability (mean disability scores of 1.44 and 1.32 respectively). In a regression model, the statistically significant baseline predictors of disability at the final survey were age, body mass index, use of anti-hypertensive medication, history of stroke, depression score, peak expiratory flow and physical disability.

CONCLUSIONS

the findings confirm reduced or delayed disability in older citizens requiring little or no hospitalization. Age, impaired peak expiratory flow and physical disability at study entry were most strongly predictive of disability, while stroke and respiratory illness were relatively common causes of severe disability.

Fasting plasma glucose in non-diabetic elderly women predicts increased all-causes mortality and coronary heart disease risk

AIM

To confirm the hypothesis that upper normal plasma glucose levels in non-diabetic subjects are independently predictive of mortality and cardiovascular disease (CVD).

METHODS

The study reports on 113 months' follow-up in a prospective study of CVD in the Australian elderly, The Dubbo Study. The cohort, first examined in 1988-89, consisted of 2805 men and women 60 years and older. Of the cohort, 2419 (86%) were defined as non-diabetic. The prediction of outcomes by quartile of fasting plasma glucose was examined in a Cox proportional hazards model, after linkage to hospital and death records.

RESULTS

All-causes mortality increased progressively across quartile of fasting plasma glucose in both sexes, reaching statistical significance only in women. Coronary heart disease (CHD) incidence increased similarly, the increases being proportionately greater in women. Ischaemic stroke did not show a consistent gradient with fasting plasma glucose. After adjustment for age and other risk factors, all-causes mortality, CHD and ischaemic stroke incidence were not significantly related to plasma glucose in men. In women, all-causes mortality and CHD incidence showed a significant gradient with glucose quartile. Hazard Ratio (95% confidence intervals) for death in glucose Quartile IV (5.3-6.0 mmol/L) was 1.49 (1.03-2.14) and for CHD incidence was 1.52 (1.08-2.15). Subjects in the upper quartiles of fasting plasma glucose showed a clustering of overweight, hypertension, elevated serum triglycerides, reduced high density lipoprotein cholesterol and excess of small dense low density lipoprotein, suggestive of the Insulin Resistance Syndrome.

CONCLUSION

Fasting plasma glucose levels in the upper normal range in non-diabetic elderly subjects appear to be associated with increased all-causes mortality and CHD, especially in women.

The A1166C mutation in the angiotensin II type I receptor and hypertension in the elderly

1. Using a nested case-control study of 661 non-institutionalized elderly (> or = 60 years) residents of Dubbo, New South Wales, Australia, the aim of this study is to determine whether the A1166C polymorphism of the angiotensin II type I (AT1) receptor gene is associated with hypertension in the elderly. 2. Individuals were classified as isolated systolic hypertension (ISH, n = 146), systolic diastolic hypertension (SDH, n = 188), or normotensive, age- and sex-matched controls (n = 327). AA, CC and AC genotypes were determined using restriction fragment length polymorphism analysis of DNA generated by nested polymerase chain reaction. 3. A univariate analysis (chi 2) was complemented by a logistic regression analysis, facilitating adjustment for potential confounders. The unadjusted genotype and allele frequencies in ISH or SDH subjects did not differ significantly from the control subjects (chi 2 = 3.0, P = 0.55, 4 d.f.; chi 2 = 3.0, P = 0.23, 2 d.f., respectively). After adjustment for potential confounders neither genotype nor allele predicted ISH or SDH in this cohort. 4. From this study we conclude that the A1166C polymorphism of the AT1 receptor gene is not a marker for ISH nor for SDH in this large, elderly community sample.

Postacute care for older aboriginal people: an exploratory-descriptive study

Many Aboriginal people reside in rural and remote Australia. Aboriginal health workers were the informants in this exploratory-descriptive study, which explored issues pertaining to postacute care for older Aboriginal people. Qualitative analysis of interview data revealed several issues were viewed as being of crucial importance in the provision of effective postacute services to older Aboriginal people. These were: (i) identification of Aboriginality; (ii) perceived racism and stereotypical attitudes among hospital staff and healthcare workers; and (iii) effective discharge planning. Other issues which were believed to impact upon service use were identified as: (i) availability of services; (ii) knowledge of services and level of use; and (iii) the notion of mainstream versus Aboriginal-specific services. Findings are discussed in relation to available literature. Implications for further research are drawn from the findings of this exploratory study.

The Center for Epidemiological Studies Depression Scale in older community samples in Indonesia, North Korea, Myanmar, Sri Lanka, and Thailand

Cultural differences in the reporting of depressive symptoms among older people were examined using the Center for Epidemiological Studies Depression (CES-D) scale in five Southeast Asian countries: Indonesia, Korea, Myanmar, Sri Lanka, and Thailand. Previous work in Asian samples--principally North American immigrants--suggested differential functioning of the CES-D. The four-factor solution established in the original studies of the CES-D was replicated for all countries using a confirmatory factor analytic approach. It was, however, demonstrated that little information was lost in considering full-scale scores rather than the four subscales separately. The behavior of the CES-D in older Asian populations was found to be comparable to results obtained in North American and European cultures. Significant somatization of depression in these Asian samples was not found. There appears to be a general factor measuring depressed mood across older populations. The results support the validity of comparing responses on the CES-D across cultures.

Risk factors for ischemic stroke: Dubbo Study of the elderly

BACKGROUND AND PURPOSE

One in 10 deaths in Australia is due to stroke. The predictors of ischemic stroke have not been well defined, although hypertension, atrial fibrillation, and previous stroke have been consistently reported. We report on 98 months' follow-up in a prospective study of cardiovascular disease in the Australian elderly, the Dubbo Study.

METHODS

The cohort, first examined in 1988, was composed of 2805 men and women 60 years and older. The prediction of ischemic stroke by potential risk factors was examined in a Cox proportional hazards model, after linkage to hospital and death records.

RESULTS

Three hundred six men and women manifested an ischemic stroke event (ICD-9-CM 433 to 437), and 95 subjects suffered a fatal stroke event. In the multivariate model, the significant independent predictors of stroke were advancing age, female sex (48% lower risk), being married (30% lower risk), prior history of stroke (227% higher risk), use of antihypertensive drugs (37% higher risk), belonging to the highest category of blood pressure reading (67% higher risk), presence of atrial fibrillation (58% higher risk), HDL cholesterol (36% lower risk for each 1-mmol/L increment), impaired peak expiratory flow (77% higher risk for tertile I than for tertile III), physical disability (59% higher risk), and depression score (41% higher risk for tertile III than for tertile I).

CONCLUSIONS

These findings suggest that morbidity and mortality associated with ischemic stroke can be predicted by various clinical indicators, some of which may be amenable to intervention. The matters of impaired peak expiratory flow, depression score, and ischemic stroke require further study.

Implementing an ambulatory surgical unit in pediatric urology

Health care professionals have been asked to do more with less and examine every possible option to cut costs but not service. To meet this challenge, a pediatric urology same-day admit/day care unit provides patients and their families with surgical and diagnostic care that has been well received by patients, families, and staff.

Hospital outcomes management: the Care Continuum and Health Outcomes Project

The Care Continuum and Health Outcomes Project is part of a national initiative to build an outcomes management approach in health care. This paper examines the baseline performance of the study. In 1995-96, 7154 Australian Capital Territory hospital inpatients were selected to take part in a five-wave survey over six months. In addition to the survey, the project involved the unit record linkage of routine data collections. A total of 5668 people (79%) agreed to participate in the survey, with 85% of these people agreeing to release their Medicare data. There were significant variations in participation rates between hospitals and wards. Factors contributing to these variations included patient socioeconomic status, disease type and illness severity. In conclusion, the success in establishing the project indicates that it is possible to conduct a broad scientific study within the health system, and that there are strong implications that ongoing scientific evaluations can be embedded within routine clinical practice.

Characteristics of longer consultations in Australian general practice

OBJECTIVE

To assess the association between general practitioner (GP) billing for "longer" consultations, patient factors linked with health care need, and other consultation characteristics.

DESIGN

Retrospective analysis of data from Medicare (1984-1992), Australian Morbidity and Treatment Survey (1990-1991) and Australian Capital Territory Record Linkage Study (1988-1992).

SETTING

Australian general practice, 1984 (introduction of Medicare) to 1992.

MAIN OUTCOME MEASURES

Consultations billed as longer (> or = 20 or > 25 minutes) compared with standard; type of billing (bulk or private); patient health care need (defined as health and sociodemographic factors linked to worse health outcomes); consultation continuity, type of care given and number of problems managed.

RESULTS

Longer billed consultations increased between 1984 and 1992, from 2.8% to 6.7% of all standard and longer consultations. Longer consultations were more likely to be bulk-billed than privately billed (odds ratio [OR], 1.74). They were more likely than standard consultations to deal with psychological diagnoses (OR, 2.06; 95% confidence interval [95% Cl], 1.83-2.32) or multiple problems (OR for four versus one diagnosis, 5.18; 95% Cl, 4.31-6.22) and to involve patients aged under 50 years, new to the practice or with new problems, but not chronic disease. In the ACT, those billed for longer consultations were more commonly tertiary educated (OR, 1.99; 95% Cl, 1.35-2.94), bulk-billed (OR, 2.75; 95% Cl, 2.51-3.10), aged 40-49 years and non-obese.

CONCLUSION

Longer billed consultations were not associated with greater patient need, other than psychosocial need, but with bulk billing and patient socioeconomic advantage. However, evaluation was complicated by the effects of continuity of care and number of problems managed in the consultation.

Relationship of peak expiratory flow rate with mortality and ischaemic heart disease in elderly Australians

OBJECTIVE

To evaluate the relationships of mortality and ischaemic heart disease (IHD) with peak expiratory flow rate (PEF) in the elderly.

DESIGN

Prospective study with median follow-up of 83 months.

SETTING

Dubbo, a New South Wales country town (population, 30500).

SUBJECTS

Non-institutionalised residents born before 1930 (i.e., aged 60 years and over at study entry). Participation rate was 73% (1235 men and 1570 women).

MAIN OUTCOME MEASURES

Baseline demographic, psychosocial and standard cardiovascular risk factors, including PEF; all-causes mortality, IHD mortality and IHD events (hospitalisations with any manifestation of IHD) by tertile of PEF.

RESULTS

More subjects with PEF in the lowest tertile (I) had a past history of respiratory disease, were current cigarette smokers and were taking antihypertensive drugs. During follow-up, 321 men (26%) and 252 women (16%) died. All-causes mortality was three (men) to four (women) times higher for those in PEF tertile I than for those in tertile III. IHD mortality and IHD events showed similar trends. In a proportional hazards model adjusted for age, height, smoking status and other risk factors or confounders, the hazard ratios (95% confidence interval) for men in PEF tertile I versus tertile III were: all-causes mortality, 1.62 (1.14-2.30); IHD mortality, 1.75 (0.96-3.20); and IHD events, 1.12 (0.82-1.53). For women, respective hazard ratios were 1.92 (1.23-3.00), 2.58 (1.24-5.39), and 1.16 (0.83-1.63).

CONCLUSIONS

We confirm an independent, inverse relationship between PEF and all-causes and IHD mortality. The data suggest a potential benefit for coronary risk factor management in subjects with existing airways disease and further support the case for antismoking programs.

Health outcomes by self-report: validity of the SF-36 among Australian hospital patients

This paper examines the performance of the SF-36 as a self-reported outcome measure in a diverse sample of Australian hospital in-patients. The data derive from the Care Continuum and Health Outcomes Project with a total of 2088 randomly selected patients, yielding a response rate of 80%. Distributions, completion rates and, in particular, correlates of measures were used to investigate the validity of the SF-36 according to clinical and psychometric criteria. Physical functioning, bodily pain, role limitations-physical, general health and vitality scales better represented physical than mental health, with the relative strength decreasing in that order; while mental health, role limitations-emotional and social functioning scales better represented mental health, with the relative strength decreasing in order. A cultural dimension was a strong independent correlate of all scales. While the SF-36 performed satisfactorily, there were weaknesses: the social functioning scale was too narrow to cover social health, both role limitations scales had crude response categories and particular subgroups, the frail elderly and those with complex health conditions, required measures with finer gradings for scales such as physical functioning and bodily pain. Further testing is needed to develop self-reports for use in hospital outcomes measurement which is already proposed in Australia.

Combined frameless stereotaxy and neuroendoscopy in placement of intracranial shunt catheters

Twenty-six patients have had cranio-peritoneal shunts placed using a new introducer allowing the combination of frameless stereotaxy and neuroendoscopy and placement of a one-piece shunt. Operating times have been acceptable, complication rates have been low, and shunt placement has been accurate in this series.

Alcohol intake and survival in the elderly: a 77 month follow-up in the Dubbo study

BACKGROUND

A prospective study in non-institutionalised Australian elderly aged 60 years and over commenced in Dubbo, NSW in 1988.

AIM

To examine the relationship between all-causes mortality and alcohol intake.

METHODS

The data were derived from a community-based sample comprising 1236 men and 1569 women followed for a median period of 77 months. Regular alcohol intake was reported by 78% of men and 52% of women. Eighty-seven per cent of men and 44% of women primarily drank beer.

RESULTS

Death occurred in 305 men and 236 women, 34% and 39% respectively from coronary heart disease (CHD). In a proportional hazards model, the hazard ratio (HR) for all-causes mortality in male drinkers, compared with abstainers, was 0.75 at one-seven drinks/week, 0.76 at eight-14 drinks/week, 0.69 at 15-28 drinks/week and 0.49 at > 28 drinks/week (p < 0.04), an inverse relationship. In female drinkers, HR was 0.78 at one-seven drinks/week, 0.49 at eight-14 drinks/week (p < 0.04) and 0.62 at 15-28 drinks/weeks, potentially a U shaped relationship. The effect on all-causes mortality could not be attributed to a differential effect of beer versus wine/spirit intake. Although the mortality rate was lower in those taking any alcohol compared with abstainers, those taking any alcohol exhibited an increased proportion of deaths due to cancer at the expense of a reduced proportion of CHD and stroke deaths.

CONCLUSIONS

Alcohol intake in the Dubbo elderly appears to be independently associated with a significant increase in life expectancy. Mechanisms underlying the effect may emerge at a longer interval of follow-up.

Sequential continuity of care by general practitioners: which patients change doctor?

OBJECTIVE

To identify individual and social characteristics of patients making sequential visits to a different rather than the same general practitioner (GP).

METHOD

Data for this study were extracted from the "Record Linkage Pilot Study" of the National Centre for Epidemiology and Population Health, which linked information from personal interviews with Health Insurance Commission and National Heart Foundation Risk Factor Survey data. Each sequence of visits (any two consecutive visits) made by each participant to the same or a different GP from January 1991 to December 1992 was treated as an event.

PARTICIPANTS

521 subjects aged between 23 and 72 years who gave consent to release of Health Insurance Commission data.

MAIN OUTCOME MEASURE

A visit to the same GP or a different GP from the one seen at the last visit.

RESULTS

Logistic regression analysis showed that younger age, good physical functioning, good self-rated health, normal body mass index, shiftwork and a longer time interval between visits were significantly associated with less continuity of care.

CONCLUSIONS

Our study raises questions about the relationship between chronological continuity and quality of care. For example, if infrequent visits (associated with less continuity) are for distinct illnesses, is quality of care affected by information or treatment from a previous visit? Our results also suggest that some GPs, because of the demography of their practices (more young people, a higher proportion of shift workers), may be disadvantaged by continuity-based reward systems. Moreover, because of lack of continuity young people may miss out on GPs' health promotional activities.