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One way to increase medical students' awareness of anatomical variability is the dissection of different cadavers throughout laboratory coursework. This report covers such a procedure successfully instituted in a human gross anatomy course.
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BACKGROUND: Hypertension is an essential risk factor for development of cardiovascular diseases. Prospective studies show a reduction in risk of myocardial infarction with reduction of blood pressure. In Denmark there was a decrease in ischaemic heart disease mortality during the period (1968-1992) with around 34% in 30-65 year old men and 30% in women. OBJECTIVE: To assess the changes in casual blood pressure between 1964 and 1991 in seven cross-sectional population studies. SETTING: Centre of Preventive Medicine, University of Copenhagen, DK-2600 Glostrup. POPULATION: 10359 subjects, equal numbers of men and women, age exactly 30, 40, 50 and 60 years drawn as random samples from a background population of 300000 inhabitants and surveyed in 1964-1974 and five cross-sectional studies 1976, 1978, 1982-1984, 1986-1987 and 1991. METHODS: Blood pressure was measured according to WHO criteria by one technician in each survey. Alcohol consumption and physical activity were measured by a self-administered questionnaire. The weight and height were measured by standardized methods. Data on mortality from ischaemic heart disease were obtained from death certificates recorded by the National Board of Health. RESULTS: Blood pressure increased with increasing age in both genders and was significantly higher in men than in women. Median blood pressure in 50 year old men in 1964 was 135/85 mmHg and in 1991 it was 123/79, whereas in women in 1964 it was 140/85, against 119/74 in 1991. The prevalence of hypertensives among 30 and 40 year olds declined throughout the period. The performance of blood pressure measurements, technical variation, examination programme, seasonal variation and inter-observer variation were potential bias sources and influenced blood pressure levels, but cannot be shown to be responsible for the declining trend in blood pressure and hypertension. Women became a little more physical active in leisure time and men less active. Women consumed less alcohol than men, but the amounts slightly increased by the end of the period. Body mass index >25 was seen less frequently in women than in men and this increased in men over the period. Sale of antihypertensive drugs increased in Denmark over the 1964-1991 period. There seems to be good agreement between the changes in blood pressure in the population and the decline in mortality from stroke and coronary heart disease in Denmark, which is influenced by other risk factors as well. CONCLUSION: Blood pressure distributions have shifted towards lower values in 1964-1991. Prevalence of hypertension declined up to 1983. Risk factor changes as well as treatment for hypertension contribute to this.
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A novel procaryotic transcriptional regulatory element, AlgP, with a histone H1-like carboxy-terminal domain was identified in Pseudomonas aeruginosa. AlgP is required for transcription of the key biosynthetic gene algD, which is necessary for production of the exopolysaccharide alginate causing mucoidy in P. aeruginosa. Mucoidy is a critical virulence determinant of P. aeruginosa invariably associated with the respiratory infections causing high mortality in cystic fibrosis. Here we show that AlgP and histones H1 both have repeated units of the Lys-Pro-Ala-Ala motif (KPAA) and its variations within their long (over 100 amino acids) carboxy-terminal domains. This region of histone H1 tails has been shown to bind to the linker DNA in eucaryotic chromatin fibers. A synthetic 50-mer peptide consisting of repeats from the AlgP carboxy-terminal domain was found to bind DNA in a mobility shift DNA-binding assay. AlgP is encoded by a gene that contains multiple direct repeats organized as tandem, head-to-tail, 12-base-pair (bp) units overlapping with six highly conserved 75-bp units. The repetitive structure of the algP gene appears to participate in the processes underlying the metastable character of mucoidy in P. aeruginosa. Relatively large DNA rearrangements spanning the region with tandem direct repeats encoding the carboxy-terminal histone H1-like structure of AlgP were detected in several strains upon conversion from the mucoid to the nonmucoid phenotype. The frequency of the detectable algP rearrangements associated with the transition into the nonmucoid state varied from strain to strain and ranged from 0 to 50%. The nonmucoid derivatives with the clearly rearranged chromosomal copy of algP were complemented to mucoidy with plasmids containing algP from P. aeruginosa PAO. When a random collection of mucoid strains, isolated from different cystic fibrosis patients, was analyzed by using polymerase chain reaction, an additional level of strain-dependent sequence variation in algP was observed. Variations in the number of the 12-bp repeats were found; however, they did not appear to influence the mucoid status of the strains examined. Thus, the repeated region of algP appears to be a hot spot for DNA rearrangements and strain-dependent variability.
In order to clarify the chloroplast genomes and structural features of ten Ilex species and provide insights into the phylogeny and genome evolution of the genus Ilex, we conducted a comparative analysis of chloroplast genomes using bioinformatics methods. The chloroplast genomes of ten Ilex species were obtained, and their structural features and variations were compared. The results indicated that all chloroplast genomes in the genus Ilex exhibit a double-stranded circular structure, with sizes ranging from 157,356 to 158,018 bp, showing minimal differences in size. The chloroplast genomes of the ten Ilex species have a relatively conservative gene count, with a total of 134 to 135 genes, including 88 or 89 protein-coding genes, and a conserved number of 8 rRNA genes. Each chloroplast genome contains 3 to 123 SSR (Simple Sequence Repeat) sites, predominantly composed of mononucleotide and trinucleotide repeats, with no detection of pentanucleotide or hexanucleotide repeats. The variation in dispersed repeat sequences among Ilex species is minimal, with a total repeat sequence number ranging from 1 to 14, concentrated in the length range of 30 to 42 base pairs. The expansion and contraction of chloroplast genome boundaries among Ilex species are relatively stable, with only minor variations observed in individual species. Variations in non-coding regions are more pronounced than those in coding regions, with the variability in the Large Single Copy region (LSC) being the highest, while the variability in the Inverted Repeat region A (IRa) is the lowest. The divergence time among Ilex species was estimated using the MCMC-tree module, revealing the evolutionary relationships among these species, their common ancestors, and their differentiation throughout the evolutionary process. The research findings provide a valuable reference for the systematic study and molecular marker development of Ilex plants.
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OBJECTIVES: Large inter-observer variation has been reported in oral radiology. Providing observers with a checklist prompting them to focus on specific radiographically visible features with known relevance to the diagnosis has been shown to improve diagnostic accuracy. We intended to investigate whether diagnostic accuracy for bony pathology could be improved by a computerized decision aid. The decision support provided the user with radiographic reference images for the degree of presence of a radiographic feature (such as radiopacity) and structured the use of diagnostic knowledge. METHODS: Twenty-seven general dental practitioners participated in the study. They diagnosed seven radiographic cases of bony pathology using a prototype decision aid and seven other cases unaided. For each radiograph the dentists assessed the degree of presence of five radiographically visible features which had been selected from the literature oral radiology because of their use in describing, radiographically visible bony pathology. The dentists' assessments of degree of feature presence, and their diagnoses, were recorded. Histopathology was used as a diagnostic 'gold standard'. The degree of presence of the features in the radiographic images was also assessed by an independently selected panel of expert oral radiologists in a Delphi consensus procedure. RESULTS: Determination of the degree of presence of three radiographically visible features assessed by the dentists using the prototype decision aid was significantly improved (by up to 12%) compared to the results of their unaided assessments. The diagnostic accuracy of one-third of the dentists was also improved. CONCLUSION: The use of reference images can improve dentists' assessments of the degree of feature presence.
To establish guidelines for the interpretation of changes in arterial blood gas (ABG) values, we studied 29 clinically stable ICU patients for spontaneous variability in PaO2, PaCO2 and pH. ABGs were sampled six times over a 50-minute period, during which all patients received a fixed FIO2 of 0.5 via endotracheal tube and underwent no therapeutic interventions. Each sample was analyzed in duplicate with careful attention to method of collection and measurement. The range separating the lowest and highest PaO2 varied from 1 to 45 mm Hg (16.2 +/- 10.9 mm Hg [mean +/- SD] ). For PaCO2 this range was from 1 to 8 mm Hg (3.0 +/- 1.9 mm Hg). Coefficient of variation for PaO2 and PaCO2 averaged 5.1 +/- 3.2 percent (mean +/- SD) and 3.0 +/- 1.5 percent respectively. pH varied within 0.03 +/- 0.02 units. Percentage change in PaO2 between sequential intrapatient samples averaged 5.3 +/- 2.8 percent (mean +/- SD) and 7.1 +/- 7.9 percent over ten- and 50-minute intervals, respectively. Various clinical features were analyzed by multiple regression analysis for their relation to PaO2 variation. Only leukocyte count and mean arterial oxygen content were statistically significant associations (p less than 0.05), but together explained less than 35 percent of the variation observed. Because considerable spontaneous variation occurs, even in stable patients, clinicians should base therapeutic decisions on trends in PaO2 values rather than on isolated changes interpreted without appropriate clinical correlation.
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Explore the source record for details and available documents.
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OBJECTIVE: To examine the impact of hospital caseload on in-hospital mortality for pediatric congenital heart surgery. DESIGN: Population-based, retrospective cohort study. SETTING: Acute care hospitals in California and Massachusetts. PATIENTS: Children undergoing surgery for congenital heart disease, identified by the presence of procedure codes indicating surgical repair of a congenital heart defect in computerized statewide hospital discharge abstract databases. Cases were grouped into four categories based on the complexity of the procedure. MAIN OUTCOME MEASURES: Adjusted odds ratios (OR) for in-hospital death were estimated using generalized estimating equations that account for the intra-institutional correlation among patients. RESULTS: A total of 2833 cases at 37 centers were identified. Compared with centers performing > 300 cases per year, after controlling for patient characteristics, centers performing < 10 cases per year had an OR for in-hospital death of 7.7 (95% confidence interval (CI) [1.6-37.8]); 10 to 100 cases, OR = 2.9 (95% CI [1.6-5.3]); 101 to 300 cases, OR = 3.0 (95% CI [1.8-4.9]). Independent risk factors for mortality included procedure complexity category (P < .0001), use of cardiopulmonary bypass (P < .0001), young age at surgery (P = .001), and transfer from another acute care hospital (P < .0001). Few differences were found by hospital caseload in length of stay or total hospital charges. CONCLUSIONS: For children with a congenital heart defect who underwent surgery in California in 1988 or Massachusetts in 1989, the risk of dying in-hospital was much lower if the surgery was performed at an institution performing > 300 cases annually. This study was limited by the absence of clinical detail in discharge abstract databases. If these findings are corroborated by other studies, health care delivery strategies that direct children requiring surgical correction of congenital heart defects to high-volume centers may substantially reduce overall mortality.
Inter-observer variations in the registration of dental age-related characteristics have not previously been studied. Examination and registration were made by 6 dentists with varying experience in age estimation. A total of 13 age-related dental characteristics in 30 teeth extracted from adults were assessed macroscopically, by stereomicroscope and from radiographs. The measurements were analysed in a microcomputer, using the SPSS/PC+ statistical package. The results showed that, except for the score on surface roughness, significant differences were found between some of the observers for all types of measurements, when a paired t-test analysis was made. The correlation coefficients between the observers varied and were rather weak for the surface roughness score. The study revealed systematic differences among the observers as well as differences in interpreting the definitions of the scores for the different parameters. Thus age estimation using statistical methods is seen to be dependent upon the experience of the individual observer and interpretation. Care should therefore be taken not to rely too much upon the results of an odontological age estimation. The possible implications of these results for forensic work are also discussed.
By introducing replicate observations into observer agreement studies, one can obtain better measures of observer agreement than heretofore possible. New methodology based on the analysis of latent variables allows a separation of within- and between-observer variation for binary measures of assessment among pairs of observers. Maximum likelihood estimation and hypothesis testing are discussed. The methodology is illustrated using data on the assessment of dysplasia by pathologists.
A new technique for morphometric measurement of vertebral bodies has been described, in which a computerized image analysis system was used to digitize and measure standardized lateral radiographs of the thoracic and lumbar spine. The sources of error in the radiographic system and the image analysis system were assessed using vertebral phantoms and test images. Oblique projection in the radiographic image of a vertebra did not produce a significant error in the measured area. The radiographic magnification was approximately 35%. Optical non-uniformity was detected in the image analysis system, and was ascribed to the lens optics. The maximum intra-observer and inter-observer variations in vertebral area were 3.1% and 5.3% respectively for experienced observers. The technique is applicable to clinical studies of large populations, and has value in investigating vertebral deformity in the management of metabolic bone disease.
We have determined the allelic structures on 106 Caucasian chromosomes at the minisatellite locus MS205 (D16S309). In addition to the internal structures deduced by minisatellite variant repeat (MVR) mapping, the genotypes at six flanking substitutional polymorphic sites have been analysed. The minisatellite structures show a polarity of variation at MS205, with most observed variation due to differences at one extremity of the tandem repeat array. This locus, therefore, provides a further example of polarity of variation at human minisatellites. Analysis of haplotypes at flanking polymorphic sites suggests that there may be a higher frequency of exchange near the highly unstable end of the minisatellite, and thus that exchanges of flanking polymorphisms may be due to co-conversion or recombination events occurring during unequal exchanges between minisatellite alleles.