Clinical applications of preheated hybrid resin composite.

This clinical article describes and discusses the use of preheated nanohybrid resin composite for the placement of direct restorations and luting of porcelain laminate veneers. Two clinical cases are presented. Preheating hybrid composite decreases its viscosity and film thickness offering the clinician improved handling. Preheating also facilitates the use of nanohybrid composite as a veneer luting material with relatively low polymerisation shrinkage and coefficient of thermal expansion compared to currently available resin luting cements.

Retrieval of a fractured abutment screw thread from an implant: a case report.

This report describes the management of a loose cement-retained implant supported crown where the thread of the abutment screw had fractured away from the body of the screw and was retained within the implant. The importance of multi-disciplinary skills in the treatment of patients with implants is discussed.

Prenatal detection of unbalanced chromosomal rearrangements by array CGH.

BACKGROUND: Karyotype analysis has been the standard method for prenatal cytogenetic diagnosis since the 1970s. Although highly reliable, the major limitation remains the requirement for cell culture, resulting in a delay of as much as 14 days to obtaining test results. Fluorescent in situ hybridisation (FISH) and quantitative fluorescent PCR (QF-PCR) rapidly detect common chromosomal abnormalities but do not provide a genome wide screen for unexpected imbalances. Array comparative genomic hybridisation (CGH) has the potential to combine the speed of DNA analysis with a large capacity to scan for genomic abnormalities. We have developed a genomic microarray of approximately 600 large insert clones designed to detect aneuploidy, known microdeletion syndromes, and large unbalanced chromosomal rearrangements. METHODS: This array was tested alongside an array with an approximate resolution of 1 Mb in a blind study of 30 cultured prenatal and postnatal samples with microscopically confirmed unbalanced rearrangements. RESULTS: At 1 Mb resolution, 22/30 rearrangements were identified, whereas 29/30 aberrations were detected using the custom designed array, owing to the inclusion of specifically chosen clones to give increased resolution at genomic loci clinically implicated in known microdeletion syndromes. Both arrays failed to identify a triploid karyotype. Thirty normal control samples produced no false positive results. CONCLUSIONS: Analysis of 30 uncultured prenatal samples showed that array CGH is capable of detecting aneuploidy in DNA isolated from as little as 1 ml of uncultured amniotic fluid; 29/30 samples were correctly diagnosed, the exception being another case of triploidy. These studies demonstrate the potential for array CGH to replace conventional cytogenetics in the great majority of prenatal diagnosis cases.

Prenatal diagnosis by array-CGH.

Microscopic karyotype analysis of cultured cells has been regarded as the gold standard for prenatal diagnosis for over 30 years. Since the first application of this technique to prenatal testing in the early 1970's, this procedure has proved to be highly reliable for identifying chromosome copy number abnormalities (aneuploidy) and large structural rearrangements in foetal cells obtained invasively by either amniocentesis or chorionic villus sampling (CVS). Recognising the need for more rapid testing methods which do not require cell culture, fluorescence in situ hybridisation (FISH) and quantitative fluorescence PCR (QF-PCR) have been introduced to this field in order to answer specific diagnostic questions. However, both FISH and QF-PCR suffer the disadvantage in that they are difficult to scale to a comprehensive, genome-wide screen. Array-comparative genomic hybridisation (array-CGH) in contrast is a comprehensive, genome-wide screening strategy for detecting DNA copy number imbalances which can be rapid, less labour-intensive than karyotype banding analysis and is highly amenable to automation. Array-CGH has the potential to be used for prenatal diagnosis and may address many of the limitations of both conventional microscopic cytogenetic analyses and the more recently employed rapid-screening strategies.

Microarray based comparative genomic hybridisation (array-CGH) detects submicroscopic chromosomal deletions and duplications in patients with learning disability/mental retardation and dysmorphic features.

The underlying causes of learning disability and dysmorphic features in many patients remain unidentified despite extensive investigation. Routine karyotype analysis is not sensitive enough to detect subtle chromosome rearrangements (less than 5 Mb). The presence of subtle DNA copy number changes was investigated by array-CGH in 50 patients with learning disability and dysmorphism, employing a DNA microarray constructed from large insert clones spaced at approximately 1 Mb intervals across the genome. Twelve copy number abnormalities were identified in 12 patients (24% of the total): seven deletions (six apparently de novo and one inherited from a phenotypically normal parent) and five duplications (one de novo and four inherited from phenotypically normal parents). Altered segments ranged in size from those involving a single clone to regions as large as 14 Mb. No recurrent deletion or duplication was identified within this cohort of patients. On the basis of these results, we anticipate that array-CGH will become a routine method of genome-wide screening for imbalanced rearrangements in children with learning disability.

Parasite plastids: maintenance and functions.

Malaria and related parasites retain a vestigial, but biosynthetically active, plastid organelle acquired far back in evolution from a red algal cell. The organelle appears to be essential for parasite transmission from cell to cell and carries the smallest known plastid genome. Why has this genome been retained? The genes it carries seem to be dedicated to the expression of just two "housekeeping" genes. We speculate that one of these, called ycf24 in plants and sufB in bacteria, is tied to an essential "dark" reaction of the organelle--fatty acid biosynthesis. "Ball-park" clues to the function of bacterial suf genes have emerged only recently and point to the areas of iron homeostasis, [Fe-S] cluster formation and oxidative stress. We present experimental evidence for a physical interaction between SufB and its putative partner SufC (ycf16). In both malaria and plants, SufC is encoded in the nucleus and specifies an ATPase that is imported into the plastid.

Eustachian valve endocarditis: a case series and analysis of the literature.

Eustachian valve endocarditis (EVE) is a syndrome characterized by clinical signs and symptoms of right-sided infective endocarditis in association with an infective vegetation on the eustachian valve. EVE usually occurs without associated involvement of any other cardiac valves, and it is difficult to diagnose accurately by transthoracic echocardiography. Transesophageal echocardiography appears to be a more sensitive tool for the diagnosis of EVE, and it is recommended when a patient with typical signs of right-sided endocarditis has normal results on a transthoracic echocardiography study. In general, EVE responds well to conventional antibiotic therapy.

Spectrum of dominant mutations in the desmosomal cadherin desmoglein 1, causing the skin disease striate palmoplantar keratoderma.

The adhesive proteins of the desmosome type of cell junction consist of two types of cadherin found exclusively in that structure, the desmogleins and desmocollins, coded by two closely linked loci on human chromosome 18q12.1. Recently we have identified a mutation in the DSG1 gene coding for desmoglein 1 as the cause of the autosomal dominant skin disease striate palmoplantar keratoderma (SPPK) in which affected individuals have marked hyperkeratotic bands on the palms and soles. In the present study we present the complete exon-intron structure of the DSG1 gene, which occupies approximately 43 kb, and intron primers sufficient to amplify all the exons. Using these we have analysed the mutational changes in this gene in five further cases of SPPK. All were heterozygotic mutations in the extracellular domain leading to a truncated protein, due either to an addition or deletion of a single base, or a base change resulting in a stop codon. Three mutations were in exon 9 and one in exon 11, both of which code for part of the third and fourth extracellular domains, and one was in exon 2 coding for part of the prosequence of this processed protein. This latter mutation thus results in the mutant allele synthesising only 25 amino acid residues of the prosequence of the protein so that this is effectively a null mutation implying that dominance in the case of this mutation was caused by haploinsufficiency. The most severe consequences of SPPK mutations are in regions of the body where pressure and abrasion are greatest and where desmosome function is most necessary. SPPK therefore provides a very sensitive measure of desmosomal function.

Genomic organization and amplification of the human desmosomal cadherin genes DSC1 and DSC3, encoding desmocollin types 1 and 3.

The desmosomal cadherins comprise the desmocollins and desmogleins and are involved in epithelial cell-cell adhesion. There are three desmocollins (DSC 1-3) and three desmogleins (DSG 1-3) that are expressed in a tissue- and development-specific manner. Desmosomal proteins have been implicated in a number of disorders characterized by loss of cell-cell adhesion and trauma-induced skin fragility. Therefore, the desmocollins are potential candidates for genodermatoses involving epithelial tissues. In order to screen the entire DSC1 and DSC3 genes, we have characterized their intron-exon organization. The DSC1 gene comprises 17 exons spanning approximately 33 kb on 18q12.1, and the DSC3 gene comprises 17 exons spanning approximately 49 kb on 18q12.1. We have also developed a comprehensive PCR-based mutation detection strategy for desmocollins 1, 2, and 3 using primers placed on flanking introns followed by direct sequencing of the PCR products.

Streptococcus pneumoniae: bacteremia in an era of penicillin resistance.

BACKGROUND: The proportion of penicillin-resistant Streptococcus pneumoniae isolates and associated risk factors varies by geographic area in the United States. We conducted a retrospective study to determine the extent of penicillin-nonsusceptible S pneumoniae bacteremia and associated risk factors in a tertiary care medical center in San Diego. METHODS: Patients with S pneumoniae bacteremia at the University of California, San Diego Medical Center from September 15, 1991, through July 31, 1998, were identified by hospital-based computerized microbiology records. Hospital records included demographic information, patient data, and antibiotic prescription records for patients with bacteremia as a result of S pneumoniae. Univariate and multivariate analyses were used to determine risk factors for penicillin-nonsusceptible S pneumoniae bacteremia. RESULTS: Of 281 isolates of S pneumoniae identified, 192 (68%) were from hospitalized patients. After controlling for other factors, patients from 1 to 5 years of age (P = .01; odds ratio [OR] = 3.96; 95% CI, 1.50 to 10.44), 6 to 18 years of age (P =.04; OR = 6.42; 95% CI, 1.13 to 36.51), and HIV seropositive patients (P =.002; OR = 5.12; 95% CI, 1.83 to 14.32) were more likely to have penicillin-nonsusceptible S pneumoniae bacteremia. There was a significant increasing trend of penicillin-nonsusceptible S pneumoniae bacteremia from 14% in 1991 to 42% in 1998 (P = .001; OR = 1.42; 95% CI, 1.16 to 1.73); this included only 2 isolates that were highly resistant to penicillin. There was no increase in mortality in patients who had penicillin-nonsusceptible S pneumoniae bacteremia. CONCLUSION: With the increase in S pneumoniae resistance to penicillin, it is important to continue surveillance of infections caused by S pneumoniae. Hospital-based studies are useful for tracking epidemiologically important pathogens.

Expanding the role of the infection control professional in the cost-effective use of antibiotics.

There is a growing demand that health care expenses be contained and that excessive and inappropriate use of antibiotics be eliminated. At the University of California, San Diego Medical Center, strategies aimed at controlling drug usage and subsequently reducing costs have been implemented and found to be effective. Mechanisms designed to achieve such goals without diminishing quality of care involve expanding the role of the infection control professional (ICP) while implementing antibiotic control stratagems such as antimicrobial utilization teams, antibiotic order sheets, audits of use, automatic stop orders, computer-assisted management, drug use reviews, educational efforts, formulary practice, restricted drug policies, and target drug monitoring. The infection control professional, as well as other members of the antimicrobial utilization team, contributes to the promotion of the appropriate use of antibiotics in part by identifying individual cases in which antibiotics might be used inappropriately, such as for the treatment of colonization rather than infection or when appropriate microbiologic testing has not been carried out.

N-terminal deletion in a desmosomal cadherin causes the autosomal dominant skin disease striate palmoplantar keratoderma.

The N-terminal extracellular domain of the cadherins, calcium-dependent cell adhesion molecules, has been shown by X-ray crystallography to be involved in two types of interaction: lateral strand dimers and adhesive dimers. Here we describe the first human mutation in a cadherin present in desmosome cell junctions that removes a portion of this highly conserved first extracellular domain. The mutation, in the DSG1 gene coding for a desmoglein (Dsg1), results in the deletion of the first and much of the second beta-strand of the first cadherin repeat and part of the first Ca2+-binding site, and would be expected to compromise strand dimer formation. It causes a dominantly inherited skin disease, striate palmoplantar keratoderma (SPPK), mapping to chromosome 18q12.1, in which affected individuals have marked hyperkeratotic bands on the palms and soles. In a three generation Dutch family with SPPK, we have found a G-->A transition in the 3" splice acceptor site of intron 2 of the DSG1 gene which segregated with the disease phenotype. This causes aberrant splicing of exon 2 to exon 4, which are in-frame, with the consequent removal of exon 3 encoding part of the prosequence, the mature protein cleavage site and part of the first extracellular domain. This mutation emphasizes the importance of this part of the molecule for cadherin function, and of the Dsg1 protein and hence desmosomes in epidermal function.

Pathogens, old and new: an update for cardiovascular nurses.

Infectious diseases remain the major cause of death throughout the world, and this is not likely to change in the foreseeable future. However, there are steps that can be taken to combat them, including both the recognition of and interventions against emerging infectious diseases. This article will provide general information about emerging infectious organisms, mechanisms of resistance to antimicrobial agents, and comments on a variety of prevention strategies. In addition, the reader is directed to a number of comprehensive references for additional information.

Caloric expenditure during cardiac rehabilitation.

PURPOSE: The purpose of this study was to describe estimated caloric expenditure among patients in a maintenance cardiac rehabilitation program relative to a stated goal of approximately 300 kcal/session or 1,000 kcal/week. Additionally, we assessed the validity of several different methods for estimating caloric expenditure. METHODS: The caloric expenditure for an exercise session was evaluated in 30 of 65 patients exercising in a maintenance cardiac rehabilitation program. Patients exercised using a treadmill, dual-action ergometer, upright stepper, or reclining stepper. The kilocalorie expenditure was assessed by three different techniques. The first used liquid crystal display (LCD) readings from the equipment (LCD method), the second combined both the American College of Sports Medicine metabolic equations for treadmill walking and the LCD values from the other equipment (Combined method), and the third measured oxygen consumption (VO2 method). RESULTS: The caloric expenditure for the LCD, Combined, and VO2 methods were 247 +/- 83, 245 +/- 80, and 230 +/- 88 kcal, respectively. Agreement between methods using intraclass correlation analysis was r = 0.84 (0.68 to 0.92, 95% confidence intervals) for LCD versus VO2 and r = 0.88 (0.77 to 0.94, 95% confidence intervals) for Combined versus VO2 method. CONCLUSIONS: Most patients (83%) in a maintenance cardiac rehabilitation program exercise below 300 kcal per session, a level believed to be necessary to illicit favorable changes in cardiovascular health. Additionally, the Combined method provides a reasonable estimate of kilocalorie expenditure. Use of kilocalorie expenditure should be considered in the cardiac rehabilitation setting as a fourth component in the exercise prescription.

Infectious complications of body piercing.

Body piercing appears to be gaining in popularity and social acceptance. With the increase in the number of piercings, it is likely that health care providers may see an increase in the complications resulting from these piercings. These may include the transmission of hepatitis viruses and bacteria at the time of the piercing or in the course of wound care. We review the infectious complications that have resulted from body piercing and have been documented in the medical literature.

The scratch test is unreliable for detecting the liver edge.

To determine the validity and reliability of the scratch test method for estimating the liver span below the right costal margin, we performed a prospective double-blind study using multiple examiners at different levels of training. Twenty-two patients were examined by 11 observers using only the scratch test. Measures of liver edge length below the right costal margin using the scratch test were compared with those by ultrasound. The validity of the scratch test was determined by simple linear regression and the concordance correlation coefficient. There was very poor correlation between the scratch test estimates and ultrasound measurements for all examiners. Measurement reliability, estimated using generalizability theory, for seven observers who examined the same nine patients was 0.68. The reliability of a single examiner was 0.24. The scratch test method for measuring the liver edge span below the right costal margin was neither a valid nor reliable method of physical examination.