Large-scale discovery of novel genetic causes of developmental disorders

Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders.

Isolation of a cDNA clone coding for a possible neural nicotinic acetylcholine receptor alpha-subunit

We have isolated a complementary DNA clone containing sequences homologous to those encoding the alpha-subunit of a mouse muscle nicotinic acetylcholine receptor. Based on the structural similarities between the encoded protein and the muscle acetylcholine receptor alpha-subunit, and the presence of hybridizing RNA species in the brain, we propose that this clone codes for a neural nicotinic acetylcholine receptor alpha-subunit.

Defining the emergence of myeloid-derived suppressor cells in breast cancer using single-cell transcriptomics

Myeloid-derived suppressor cells (MDSCs) are innate immune cells that acquire the capacity to suppress adaptive immune responses during cancer. It remains elusive how MDSCs differ from their normal myeloid counterparts, which limits our ability to specifically detect and therapeutically target MDSCs during cancer. Here, we sought to determine the molecular features of breast cancer-associated MDSCs using the widely studied mouse model based on the mouse mammary tumor virus (MMTV) promoter-driven expression of the polyomavirus middle T oncoprotein (MMTV-PyMT). To identify MDSCs in an unbiased manner, we used single-cell RNA sequencing to compare MDSC-containing splenic myeloid cells from breast tumor-bearing mice with wild-type controls. Our computational analysis of 14,646 single-cell transcriptomes revealed that MDSCs emerge through an aberrant neutrophil maturation trajectory in the spleen that confers them an immunosuppressive cell state. We establish the MDSC-specific gene signature and identify CD84 as a surface marker for improved detection and enrichment of MDSCs in breast cancers.

Canine ventricular arrhythmias in the late myocardial infarction period. 8. Epicardial mapping of reentrant circuits

We made simultaneous recordings from 48 bipolar electrodes to obtain epicardial isochronal maps during induced ventricular arrhythmias in dogs 3-5 days after ligation of the left anterior descending artery. There was strong evidence of a reentrant circuit (RC) that was discernible largely on the epicardial surface in 21% of ectopic beats that were analyzed. Epicardial recordings were of limited value in analyzing the arrhythmia in other beats. The reentrant circuit consisted of an arc of conduction block around which the activation front advanced in a circular fashion at slow but uneven speeds while the rest of the ventricle was activated by radial spread. The arc of conduction block around which the RC was formed was usually functional in nature, since the same area of myocardium was excitable at relatively long cardiac cycle lengths. Both the length of the arc of conduction block which defines the length of the reentrant circuit and the degree of conduction delay were crucial factors for the occurrence of reentry. A premature beat that initiated reentry resulted in a longer arc of conduction block and slower conduction compared to one that failed to induce reentry.

EEG power, frequency, asymmetry and coherence in male depression

Quantitative electroencephalographic (EEG) power topography has served as a useful tool for investigating brain regional mechanisms underlying affective disorders. In an attempt to examine the role of gender and widen the scope of the measurement probes used in these investigations, the traditional power and inter-hemispheric power ratio indices were supplemented with intra-hemispheric power ratios, mean frequency and both inter and intra-hemispheric coherence indices, in the comparison of depressed male patients and healthy controls. Resting (eyes closed), vigilance controlled EEG recordings from 21 scalp sites were collected from 70 male, unmedicated, unipolar major depressive disorder outpatients and 23 normal control male subjects. Absolute and relative power, frequency, asymmetry and coherence measures derived from spectrally analyzed EEGs were subjected to univariate analyses for group comparisons as well as to discriminant function analysis to examine their utility as classification indices. Compared with controls, patients evidenced greater overall relative beta power and, at bilateral anterior regions, greater absolute beta power and faster mean total spectrum frequency. Inter-hemispheric alpha power asymmetry index differences were noted, with controls exhibiting relatively reduced left hemisphere activation, and widespread reduced delta, theta, alpha and beta coherence indices. Whereas intra-hemispheric theta power asymmetry reduction was exhibited in patients bilaterally at all regions, group differences with intra-hemispheric beta power asymmetry were unilateral, being restricted to the right hemisphere. Discriminant analysis correctly classified 91.3% of the patients and controls. Quantitative EEG measurements in male depression appear to describe a pattern of aberrant inter-hemispheric synchrony/asymmetry and a profile of frontal activation.

Selective expansion of intraepithelial lymphocytes expressing the HLA-E-specific natural killer receptor CD94 in celiac disease

BACKGROUND & AIMS

Celiac disease is a gluten-induced enteropathy characterized by the presence of gliadin-specific CD4(+) T cells in the lamina propria and by a prominent intraepithelial T-cell infiltration of unknown mechanism. The aim of this study was to characterize the subset(s) of intraepithelial lymphocytes (IELs) expanding during active celiac disease to provide insights into the mechanisms involved in their expansion.

METHODS

Flow-cytometric analysis of isolated IELs and/or immunohistochemical staining of frozen sections were performed in 51 celiac patients and 50 controls with a panel of monoclonal antibodies against T-cell and natural killer (NK) receptors. In addition, in vitro studies were performed to identify candidate stimuli for NK receptor expression.

RESULTS

In normal intestine, different proportions of IELs, which were mainly T cells, expressed the NK receptors CD94/NKG2, NKR-P1A, KIR2D/3D, NKp46, Pen5, or CD56. During the active phase of celiac disease, the frequency of CD94(+) IELs, which were mostly alphabeta T cells, was conspicuously increased over controls. In contrast, the expression of other NK markers was not modified. Furthermore, expression of CD94 could be selectively induced in vitro by T-cell receptor activation and/or interleukin 15, a cytokine produced by intestinal epithelial cells.

CONCLUSIONS

The gut epithelium favors the development of T cells that express NK receptors. In active celiac disease, there is a specific and selective increase of IELs expressing CD94, the HLA-E-specific NK receptor that may be related to T-cell receptor activation and/or interleukin 15 secretion.

Influence of the MexAB-OprM multidrug efflux system on quorum sensing in Pseudomonas aeruginosa

Pseudomonas aeruginosa nalB mutants which hyperexpress the MexAB-OprM multidrug efflux system produce reduced levels of several extracellular virulence factors known to be regulated by quorum sensing. Such mutants also produce less acylated homoserine lactone autoinducer PAI-1, consistent with an observed reduction in lasI expression. These data suggest that PAI-1 is a substrate for MexAB-OprM, and its resulting exclusion from cells hyperexpressing MexAB-OprM limits PAI-1-dependent activation of lasI and the virulence genes.

Manual-assisted cognitive-behaviour therapy (MACT): a randomized controlled trial of a brief intervention with bibliotherapy in the treatment of recurrent deliberate self-harm

BACKGROUND

The treatment of deliberate self-harm (parasuicide) remains limited in efficacy. Despite a range of psychosocial, educational and pharmacological interventions only one approach, dialectical behaviour therapy, a form of cognitive-behaviour therapy (CBT), has been shown to reduce repeat episodes, but this is lengthy and intensive and difficult to extrapolate to busy clinical practice. We investigated the effectiveness of a new manual-based treatment varying from bibliotherapy (six self-help booklets) alone to six sessions of cognitive therapy linked to the booklets, which contained elements of dialectical behaviour therapy.

METHODS

Thirty-four patients, aged between 16 and 50, seen after an episode of deliberate self-harm, with personality disturbance within the flamboyant cluster and a previous parasuicide episode within the past 12 months, were randomly assigned to treatment with manual-assisted cognitive-behaviour therapy (MACT N = 18) or treatment as usual (TAU N = 16). Assessment of clinical symptoms and social function were made at baseline and repeated by an independent assessor masked to treatment allocation at 6 months. The number and rate of all parasuicide attempts, time to next episode and costs of care were also determined.

RESULTS

Thirty-two patients (18 MACT; 14 TAU) were seen at follow-up and 10 patients in each group (56% MACT and 71% TAU) had a suicidal act during the 6 months. The rate of suicidal acts per month was lower with MACT (median 0.17/month MACT; 0.37/month TAU; P = 0.11) and self-rated depressive symptoms also improved (P = 0.03). The treatment involved a mean of 2.7 sessions and the observed average cost of care was 46% less with MACT (P = 0.22).

CONCLUSIONS

Although limited by the small sample, the results of this pilot study suggest that this new form of cognitive-behaviour therapy is promising in its efficacy and feasible in clinical practice.

Loss of regional bone mineral density in the first 12 months following renal transplantation

A high incidence of osteopenia is likely in renal transplant recipients in whom pre-existing uraemic osteodystrophy, persisting hyperparathyroidism and glucocorticoids constitute a formidable array of risk factors. The correction of some biochemical and hormonal abnormalities, an increase in body weight and an increase in physical activity following transplantation could favour improvements in skeletal integrity. Using dual energy X-ray absorptiometry (DEXA), we studied prospectively the regional bone mineral density (BMD) of 34 consecutive cadaveric renal allograft recipients who were already established on dialysis. BMD of these patients was measured at the time of transplantation and was repeated at 3, 6 and 12 months following the transplantation. Immunosuppression was achieved using triple therapy: azathioprine, cyclosporin-A and prednisolone. At baseline, total BMD and BMD at the lumbar spine and femoral neck did not differ from age- and sex-matched controls. Females experienced marked and progressive bone loss at the lumbar spine, with less marked changes at the femoral neck. Males, in contrast, experienced substantial reduction of BMD at the femoral neck at 6 months and a recovery at 12 months without significant change at the lumbar spine. Whole body bone mineral content fell transiently in males, with partial recovery by 6 months. No significant correlation was found with the cumulative doses of either corticosteroids or cyclosporin-A, the duration of hospitalisation, the function of the transplant, patient age or menopausal status.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting cervical anastomotic leak and stricture formation following esophagogastrectomy and gastric tube interposition

Following esophagectomy, restoration of swallowing by gastric tube interposition with cervical esophagogastric anastomosis reduces morbidity and mortality associated with intrathoracic anastomoses at the expense of an increased incidence of both anastomotic leak and stricture formation. A retrospective study of 165 patients with either squamous cell carcinoma or adenocarcinoma of the distal esophagus or gastric cardia undergoing esophagogastrectomy with gastric tube interposition and cervical anastomosis at Vancouver, British Columbia, or London, Ontario, was undertaken. Forced-entry multiple logistic regression analysis of factors believed to influence anastomotic outcome was performed. Anastomotic leak occurred in 17% of patients; statistically significant correlation with low preoperative serum albumin (p = 0.005), running suture technique (p = 0.029), high intraoperative blood loss (p = 0.038), and the occurrence of postoperative delayed gastric emptying (p = 0.045) was found. Anastomotic strictures occurred in 31% of patients; a statistically significant correlation was found with preceding anastomotic leak (p = 0.001) and intraoperative blood loss (p = 0.042). Factors including preoperative radiotherapy and diabetes mellitus were not found to be significant.

Randomized placebo-controlled trial of brisk walking in the prevention of postmenopausal osteoporosis

OBJECTIVE

to evaluate the effects of brisk walking on bone mineral density in women who had suffered an upper limb fracture.

DESIGN

randomized placebo-controlled trial. Assessments of bone mineral density were made before and at 1 and 2 years after intervention. Standardized and validated measures of physical capacity, self-rated health status and falls were used.

SETTING

district general hospital outpatient department.

SUBJECTS

165 women drawn from local accident and emergency departments with a history of fracture of an upper limb in the previous 2 years. Women were randomly allocated to intervention (self-paced brisk walking) or placebo (upper limb exercises) groups.

INTERVENTION

both groups were seen at 3-monthly intervals to assess progress, measure physical capacity and maintain enthusiasm. The brisk-walking group were instructed to progressively increase the amount and speed of walking in a manner that suited them. The upper limb exercise placebo group were asked to carry out a series of exercises designed to improve flexibility and fine hand movements, appropriate for a past history of upper limb fracture.

RESULTS

drop-outs from both intervention and placebo groups were substantial (41%), although there were no significant differences in bone mineral density, physical capacity or health status between drop-outs and participants. At 2 years, among those completing the trial, bone mineral density at the femoral neck had fallen in the placebo group to a greater extent than in the brisk-walking group [mean net difference between intervention and placebo groups 0.019 g/cm2, 95% confidence interval (CI) -0.0026 to +0.041 g/cm2, P = 0.056]. Lumbar spine bone mineral density had increased to a similar extent (+0.017 g/cm2) in both groups. The cumulative risk of falls was higher in the brisk-walking group (excess risk of 15 per 100 person-years, 95% CI 1.4-29 per 100 person-years, P < 0.05). There were no significant differences in clinical or spinal x-ray fracture risk or self-rated health status between intervention and placebo groups.

CONCLUSION

the promotion of exercise through brisk-walking advice given by nursing staff may have a small, but clinically important, impact on bone mineral density but is associated with an increased risk of falls. Self-paced brisk walking is difficult to evaluate in randomized controlled trials because of drop-outs, placebo group exercise, limited compliance and lack of standardization of the duration and intensity of walking. Further work is needed to evaluate the best means of safely achieving increased activity levels in different groups, such as older women and those at high risk of fractures.

Making sense of dementia and adjusting to loss: psychological reactions to a diagnosis of dementia in couples

The current emphasis on early detection and disclosure of a diagnosis of dementia highlights the need to examine couples' shared constructions of, and responses to, the diagnosis, and to explore the appraisals that couples make about the illness at an early stage. While the experiences of carers and of people with dementia have mostly been considered separately, further investigation of the shared experience of couples where one partner is developing dementia is required. This study adopted a family systems perspective to investigate psychological reactions to a diagnosis of dementia in nine couples where one partner had received a diagnosis of either Alzheimer's disease or vascular dementia, with particular emphasis on the possible relevance of psychological responses to loss. Interpretative phenomenological analysis was used to explore participants' experiences of receiving a diagnosis of dementia, which were compared and contrasted across couples. Ten themes were subsumed under two higher-order themes, 'Not quite the same person, tell me what actually is wrong' and 'Everything's changed, we have to go from there', and linked through the overarching theme of 'Making sense and adjusting to loss'. A model is presented that encapsulates the oscillating processes couples appeared to go through in making sense of the experience of early-stage dementia and adjusting to the losses and difficulties evoked by the illness, which appeared to be similar to the process of adjustment outlined in dual-process models of grief. The findings suggest that couples who receive a diagnosis of dementia may be supported by helping them to create a joint construction that enables them to make sense of their situation, find ways of adjusting to the changes experienced in their roles and identity, and manage the losses they face in the early stages of dementia.

Spina bifida and anencephalus in greater London

In order to make comparisons with the findings in a high frequency area, South Wales, with those in a low frequency area, south-east England, a birth frequency and family study was made of all births with neural tube malformations (spina bifida cystica, encephalocele, anencephaly, and iniencephaly) in 32 of the 33 London Boroughs over a 3-year period from 1 April 1965 to 31 March 1968. The births were ascertained through local authority registers, stillbirth and infant death certificates, and hospital records. The frequencies found were 1·54 for spina bifida (including encephalocele) and 1·41 for anencephaly (including iniencephaly). This was less than four tenths of the South Wales frequency. Evidence of an excess of winter births was found for both types of malformation, with a peak for conceptions in February, March, and April.

The parents of 870 of the original 1209 index patients were traced and visited for the family survey. The usual social class effect was seen, a deficit of fathers in social class I and II. The birth order distribution of legitimately born patients standardized for maternal age showed only a small excess of firstborn and a deficit rather than an excess of lateborn. For maternal age, however, standardized for birth order, there was an excess of patients born to mothers under 20 and over 35 years of age. The whole family study sample showed a striking excess of patients born to parents from India and Pakistan compared to parents born in the West Indies in relation to households of immigrant parents in the 1966 sample Census. A small sample of 164 patients with matched controls had more parents born in Ireland and India and Pakistan and fewer born in south-east England and the West Indies than the controls.

The proportions of sibs affected with spina bifida and anencephaly were 3·42% for spina bifida index patients and 5·44% for anencephaly. For patients born after the index patient the proportions were 5·17 and 4·17%, respectively. The overall risk to sibs was lower than that shown in the South Wales survey, but substantially higher relative to the population birth frequency. The risk to sibs was not apparently influenced by father's social class but there was an indication of an effect of mother's father's social class, with a lower risk where mother had grown up in a class I, II, or IIIa home. There was no apparent influence of grandparental birth place. There was no apparent effect of a relative affected other than a sib. Among cousins a significant increase over the population birth frequency was seen only in mother's sisters' children.

The findings, like those of earlier surveys, suggest a multifactorial aetiology of the neural tube malformations, depending both on genetic predisposition and environmental triggers.

Quorum-sensing and siderophore biosynthesis in Pseudomonas aeruginosa: lasR/lasI mutants exhibit reduced pyoverdine biosynthesis

Cell density-dependent gene expression in Pseudomonas aeruginosa is controlled, in part, by the quorum-sensing regulator LasR. lasR null mutants exhibited a reproducible 2-fold decrease in production of the catecholate-hydroxamate siderophore pyoverdine during grown under iron-limiting conditions. Similarly, lasI mutants defective in the biosynthesis of the autoinducer PAI-1 also exhibited a 2-fold decrease in pyoverdine production which could be largely restored upon addition of exogenous PAI-1. lasR mutants were not altered with respect to expression of the pvdD gene involved in the synthesis of the peptide portion of pyoverdine, indicating that some other pyoverdine biosynthetic gene(s) were affected by the LasRI status of the cell. This represents the first report of quorum-sensing regulation of siderophore production in bacteria and highlights the fact that cell density, while not an essential signal for pyoverdine expression, does enhance production of this siderophore.

Pamidronate therapy as prevention of bone loss following renal transplantation

BACKGROUND

Very rapid bone loss, osteopenia and skeletal morbidity after renal transplantation have been well documented and found to occur in a sex dependent fashion. Glucocorticoids, cyclosporine and pre-existing uremic osteodystrophy have been implicated in the pathogenesis of the skeletal lesions. Glucocorticoid induced osteopenia is also a serious clinical problem in patients with various nonrenal diseases and can be prevented, or at least attenuated, by pamidronate and other bisphosphonates.

METHOD

We prospectively studied 26 male patients undergoing renal transplantation, and randomized them to receive either placebo or intravenous pamidronate (0.5 mg/kg) at the time of transplantation and again one month later. All patients received immunosuppression comprising prednisolone, cyclosporine and azathioprine. The bone mineral density (BMD) of the second, third and fourth lumbar vertebrae and of the femoral neck was measured at the time of transplantation and at three months and 12 months after transplantation using dual energy X-ray absorptiometry (DXA).

RESULTS

Twelve months after transplantation, the mean (+/- SEM) BMD of the lumbar vertebrae in patients who received placebo had decreased 6.4% (P < 0.05). In contrast, patients who received pamidronate experienced no significant reduction of BMD at the lumbar vertebrae. At the femoral neck, placebo-treated patients showed a reduction of BMD of 9% (P < 0.005), whereas there was no significant change in the pamidronate treated group. The two study groups had similar patient profiles, serum parathyroid hormone (PTH) and aluminium concentrations. After transplantation, comparable falls in the serum creatinine and PTH concentration were found in the two groups. Apart from transient hypocalcemia in two patients, no significant adverse effects of pamidronate were noted.

CONCLUSION

This study has shown that the early rapid bone loss that occurs in men during the first 12 months after renal transplantation can be prevented by two intravenous doses of pamidronate given at transplantation and one month later. The regimen was simple to administer, well tolerated and potentially applicable to other clinical groups of glucocorticoid treatment patients.

Protein machines and lipid assemblies: current views of cell membrane fusion

Protein machines and lipid bilayers both play central roles in cell membrane fusion, a process crucial to life. Recent results provide clues to how both components function in fusion. Recent observations suggest a common mechanism by which very different fusion machines (from lipid-enveloped viruses and synaptic vesicles) may function to produce compartment-joining pores. This mechanism presumes that fusion proteins act as machines that use stored conformational energy to assemble closely juxtaposed lipid bilayers, bend these to form fusion-competent structures, stabilize unfavorable lipid structures and destabilize a committed intermediate to drive fusion pore formation.

A randomised controlled study of close monitoring of vulnerable psychiatric patients

The care programme approach was introduced in mental health services in the UK in 1991. It was intended to improve the quality of care and prevent patients losing contact with care services and, by implication, to reduce psychiatric admissions. We did a study to find out if the approach worked. 400 patients from a London inner-city area who had been identified as psychiatrically vulnerable and included on a case register of patients with special needs were randomised into two groups of 200 each. One group received close supervision by nominated key-workers (as recommended in the care programme approach of the UK Department of Health), and the other received standard follow-up from psychiatric and social services. Outcome was recorded after eighteen months. Data on 393 patients was available for analysis. Of 197 patients allocated to standard care, 64 (32.5%) were lost to follow-up compared with 40 (20.4%) of 196 patients receiving close supervision (p = < 0.005). However, patients under close supervision had significantly more admissions (30% vs 18%, chi 2 = 7.61, p < 0.01) and spent 68% more days in hospital than the standard group. The findings of greater hospital-bed use, which differ from those of studies with community-based psychiatric teams, suggest that close supervision by a single key worker, as recommended in the care programme approach, will lead to greater success in maintaining contact with vulnerable patients, but is likely to lead to more psychiatric admissions.

MexR repressor of the mexAB-oprM multidrug efflux operon of Pseudomonas aeruginosa: identification of MexR binding sites in the mexA-mexR intergenic region

The MexR repressor of the mexAB-oprM multidrug efflux operon of Pseudomonas aeruginosa was purified as a C-terminal histidine-tagged protein by metal chelate affinity chromatography. The purified protein was shown to bind ca. 200 bp upstream of mexA, at two sites, each of which contains a repeat of the nucleotide sequence GTTGA in inverse orientation. DNA sequence analysis identified mexA and mexR promoters within the MexR binding regions, consistent with the previously observed negative regulation of mexR and mexAB-oprM expression by MexR. Transcription of mexA from the promoter originating within the MexR binding site II was confirmed and shown to be markedly enhanced in a nalB (i.e., mexR) mutant of P. aeruginosa. A second mexA promoter was also identified, ca. 70 bp upstream of mexAB-oprM, and transcription from this promoter appeared to occur in both the wild type and a nalB mutant. Production of MexAB-OprM in wild-type cells may be due to expression from a constitutively expressed proximal promoter, while MexAB-OprM hyperexpression in nalB mutants is due to the additional expression from a MexR-regulated distal promoter.

Surgical clips in planning the electron boost in breast cancer: a qualitative and quantitative evaluation

PURPOSE

To evaluate, qualitatively and quantitatively, the role of surgical clips in planning the tumor bed electron boost in patients undergoing breast conserving surgery and radiotherapy.

METHODS AND MATERIALS

In 50 patients, the excision cavity boundaries were marked by clips at surgery. The electron boost field was first planned using clinical information, aiming to achieve a margin of 2 cm, and its accuracy evaluated by screening the surgical clips and, if necessary, adjusting the field to encompass all clips with 2 cm margins. Orthogonal radiographs were take with solder wire delineating the clinical and screened fields and the scar. Hypothetical clinical and radiological fields, with 1 and 3 cm margins, were reconstructed on the radiographs.

RESULTS

The clinical field was inadequate in 34 patients (68%). The precision of each clinical setup was quantified by two indices. The Normal Tissue Index defined the percentage of the clinical field comprised of tissue, beyond the tumor bed, not at high risk of local recurrence, and gave an estimate of potential spring of normal tissue: median 14.6% (range 0-83.0), 17 out of 50 > 25%; median 13% (range 0-70.7), 12 out of 50 > 25%; median 9.7% (range 0-59.8), 10 out of 50 > 25%, for 1, 2, and 3 cm margins, respectively. The Geographical Miss Index defined the percentage of the radiologically defined field, at high risk of local recurrence, not predicted by the clinical field, and gave an estimate of the extent of geographical miss: median 32.9% (range 0-83.5), 28 out of 50 > 25%; median 26.1% (range 0-69.8%), 26 out of 50 > 25%; median 18.6% (range 0-60.3), 20 out of 50 > 25%, for 1, 2, and 3 cm margins, respectively. The median distance from the scar midpoint to the furthest clip was 3.8 (range 1.2-8.1) cm. The median maximal clip depth was 3.1 (range 1.4-5.2) cm.

CONCLUSION

(a) Electron boost field planning by clinical landmarks alone was inaccurate in 68% of cases. (b) Quantitative measures, based on margins of 1, 2, and 3 cm, revealed that in 20-34% of patients more than one-quarter of the clinical field covered tissue at low risk of local recurrence, and in 40-56% of patients less than three-quarters of the final radiological field was predicted clinically. (c) The relative positions of the scar and clips may be widely disparate. (d) Clip depth measurements reveal a significant risk of underdosing at depth.

Identification of a sixth locus for autosomal dominant retinitis pigmentosa on chromosome 19

We report the mapping of a sixth locus for autosomal dominant retinitis pigmentosa (adRP) to 19q13.4. After a total genome linkage search using over 300 markers in a single large pedigree, marker loci on the long arm of chromosome 19 showed significant linkage with the disease locus. Since the mapping information for the marker loci used in this study was derived from two different genome maps, we established genetic distances between relevant marker loci so that linkage information could be combined from both maps. A conventional three point analysis between the adRP phenotype and markers D19S180 and D19S214 gave a maximum lod score of 4.87. Combining data from these and other markers, we used the recently described multiple two point programme FASTMAP to simulate a multipoint analysis of the full data set. This gave a lod score of 5.34 in the interval between markers D19S180 and D19S214. Recently this laboratory has also reported the linkage of another form of retinal degeneration known as cone-rod dystrophy (CRD) to a genetically different set of markers from 19q. Linkage data presented here clearly supports the existence of two separate retinal genes in this part of the genome.

Spoilation and clinical performance of monthly vs. three monthly Group II disposable contact lenses

Twelve subjects were fitted with a high water content, nonionic contact lens (Pilkington Barnes-Hind "Precision UV"), which was either replaced every month for 3 months or worn for 3 consecutive months before replacement occurred. Visual quality, high and low contrast acuity, and comfort were unaltered with either replacement schedule, but overall satisfaction was significantly greater with the shorter replacement schedule (p = 0.04). Front surface wettability revealed a large amount of intersubject variability and was reduced at the 3-month visit with the longer replacement period lenses (p = 0.003). Visible deposits also increased with longer replacement times (p < 0.05). Laboratory-based analytical results showed that both gross lipid and gross extractable protein significantly increased in the 3-month lenses compared with the 1-month lenses, with 44% less lipid accumulation and 60% less protein deposition occurring with the shorter replacement time. The results support the replacement of high water content lenses on a monthly basis.

True incidence of pacemaker syndrome

Although the purported incidence of pacemaker syndrome according to the literature is only 5%-15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either VVI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (P less than 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough, and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the VVI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical, hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode.

An in vivo comparison of the kinetics of protein and lipid deposition on group II and group IV frequent-replacement contact lenses

PURPOSE

To investigate the degree and rate of deposition of protein and lipid on FDA group II and group IV contact lens materials over a period of up to 28 days of wear.

METHODS

Twenty-two subjects wore a group IV lens (Acuvue) and a group II lens (Soflens 66) in a randomized, cross-over study. The lenses were randomly worn for periods between 1 and 28 days and then collected for laboratory-based deposition analysis.

RESULTS

The group II lenses revealed an increased degree of lipoidal spoilage (p < 0.0001) and the group IV lenses exhibited increased protein spoilage (p < 0.0001). Surface protein for both materials reached a maximum after 1 day and did not increase over the 4-week wearing period (p = NS). Total protein for group IV lenses reached a maximum between 1 and 7 days and then reached a plateau, with no further increase occurring (p = NS), whereas total protein accumulation on the group II lens continued to increase across all time periods (p < 0.05). Lipid deposition on the group IV lens was maximal after 1 day and increased no further (p = NS), whereas lipid deposition on the group II material monotonously increased and progressively built-up over the 4 weeks of wear (p < 0.0001).

CONCLUSIONS

The kinetics of contact lens deposition is mediated by the chemical structure of the contact lens material under consideration. Protein deposition occurs rapidly with group IV materials before reaching a maximum, whereas N-vinyl pyrrolidone-containing group II materials progressively accumulate protein and lipid deposits, with no plateau occurring.

An insight into the epidemiology of dolphin morbillivirus worldwide

Serum samples from 288 cetaceans representing 25 species and originating from 11 different countries were collected between 1995 and 1999 and examined for the presence of dolphin morbillivirus (DMV)-specific antibodies by an indirect ELISA (iELISA) (N = 267) or a plaque reduction assay (N = 21). A total of 35 odontocetes were seropositive: three harbour porpoises (Phocoena phocoena) and a common dolphin (Delphinus delphis) from the Northeastern (NE) Atlantic, a bottlenose dolphin (Tursiops truncatus) from Kent (England), three striped dolphins (Stenella coeruleoalba), two Risso's dolphins (Grampus griseus) and a bottlenose dolphin from the Mediterranean Sea, one common dolphin from the Southwest (SW) Indian Ocean, three Fraser's dolphins (Lagenodelphis hosei) from the SW Atlantic, 18 long-finned pilot whales (Globicephala melas) and a bottlenose dolphin from the SW Pacific as well as a captive bottlenose dolphin (Tursiops aduncus) originally from Taiwan. The presence of morbillivirus antibodies in 17 of these animals was further examined in other iELISAs and virus neutralization tests. Our results indicate that DMV infects cetaceans worldwide. This is the first report of DMV-seropositive animals from the SW Indian, SW Atlantic and West Pacific Oceans. Prevalence of DMV-seropositives was 85.7% in 21 pilot whales from the SW Pacific and both sexually mature and immature individuals were infected. This indicates that DMV is endemic in these animals. The same situation may occur among Fraser's dolphins from the SW Atlantic. The prevalence of DMV-seropositives was 5.26% and 5.36% in 19 common dolphins and 56 harbour porpoise from the NE Atlantic, respectively, and 18.75% in 16 striped dolphins from the Mediterranean. Prevalence varied significantly with sexual maturity in harbour porpoises and striped dolphins; all DMV-seropositives being mature animals. The prevalence of seropositive harbour porpoise and striped dolphins appeared to have decreased since previous studies. These data suggest that DMV is not endemic within these populations, that they are losing their humoral immunity against the virus and that they may be vulnerable to new epidemics.