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PubMed1994

Diagnosis and monitoring of amyloidosis.

The diagnosis of systemic amyloidosis is only occasionally suspected on clinical grounds alone and is more often considered when an associated condition, such as a chronic inflammatory disease or monoclonal gammopathy, is present. No blood test is diagnostic of amyloid although routine haematological and biochemical investigations have important roles in defining the underlying disease process in amyloidosis, and evaluating organ function. A number of non-invasive investigations including echocardiography, electrocardiography and soft tissue scintigraphy with bone-seeking tracers give characteristic results in some patients with amyloidosis, but are non-specific. The diagnosis can only be confirmed by demonstrating the presence of amyloid deposits in the tissues. Histology is the traditional method in routine clinical practice and is sensitive for revealing microscopic deposits and permits immunotyping of fibril proteins. Disadvantages are that biopsies are invasive, open to sampling error and can only give limited information on the distribution and extent of amyloid deposits in an individual. Scintigraphic and turnover studies with radioiodinated SAP are new specific methods for confirming the presence of amyloid in tissues, based on the affinity of SAP for all types of amyloid fibril. Labelled SAP scans survey the whole body macroscopically for the presence and anatomical distribution of amyloid in a quantitative manner, and SAP turnover studies provide information on the whole body amyloid load. Although the availability of SAP scintigraphy presently remains restricted, the technique has been used in over 400 patients with amyloid in prospective studies, and has already provided a number of new insights into the natural history of amyloidosis. These include the observation that there is a consistently poor correlation between the quantity of amyloid in an organ and the resulting degree of functional impairment. Amyloid deposits accumulate at rates which vary substantially between different organs in a single subject and between individuals with similar types of amyloidosis, even when the rates of amyloid fibril precursor protein supply are apparently similar. In some patients amyloid accumulation may plateau without any measurable alteration in the precursor supply. In patients with amyloidosis in whom the supply of fibril precursors is reduced, either as a result of therapy directed towards the underlying process or through a natural remission, substantial regression of amyloid frequently occurs. This has been observed in patients with AA, AL and variant TTR-associated amyloidosis, and is usually associated with clinical benefits. In some such cases, however, the function of affected organs may continue to deteriorate despite halting the accumulation of amyloid, presumably because irreversible structural damage has already occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Amyloid↗
PubMed1996

Percutaneous needle biopsy and synovial histology.

Percutaneous needle biopsies of synovium are successfully used for diagnosis and investigation of joint disease by an increasing number of groups around the world. This procedure can be done in the office with little morbidity; a large number of samples can minimize the potential limitation of sampling error. Clinical indications for 'imaging the joint' by looking at morphological and other features of the actual tissue include undiagnosed acute or chronic mono- or oligoarthritis, haemarthrosis, suspected deposition diseases, new developments in previous stable disease and less often unexplained polyarthritis. Research into any joint disease can be helped by study of synovium especially using newer immunohistochemical, EM and molecular techniques. This report has reviewed other methods used for obtaining synovium, described the different percutaneous biopsy needles, detailed the methods used for biopsy with the Parker-Pearson needle and described how our group handles tissue so as to obtain maximal impact. The very few side effects of needle biopsy include haemarthrosis and, rarely, needle breakage. Finally, we have provided a brief overview of normal synovium and some aspects of synovium in a variety of joint diseases.

Arthritis↗
PubMed2001

Malignant transformation in synovial chondromatosis of the knee?

Although it has been reported, malignant transformation of synovial chondromatosis is rare. We report a case of malignant transformation of synovial chondromatosis in a knee to a low-grade chondrosarcoma, which was treated with synovial excision and total knee replacement. We also present a literature review of the subject. The case illustrates that malignant transformation should be suspected in chronic cases with a sudden exacerbation of symptoms and that interpretation of histology in cartilage lesions is difficult. It also demonstrates that even when guided biopsy techniques are used, the sampling error of a needle biopsy in any large lesion is unavoidable.

Bone Neoplasms↗
PubMed2003

Histology of Barrett's esophagus and dysplasia.

This article explores issues related to the diagnosis of Barrett's esophagus (BE) in endoscopic biopsies and dysplasia in Barrett's epithelium. The definitions of BE, including long- and short-segment BE, are reviewed, with an emphasis on the significance of intestinal metaplasia (IM). IM of the gastroesophageal junction and cardia is reviewed and problems in its distinction from short-segment BE are discussed. In addition, the article reviews the classification of dysplasia in Barrett's mucosa, with reference to problematic areas, such as sampling error and interobserver variability. Biomarkers and their role in the diagnosis of dysplasia and stratification of risk are summarized.

Barrett Esophagus↗
PubMedDate not supplied

Burden of myocardial damage in cardiac allograft rejection: scintigraphic evidence of myocardial injury and histologic evidence of myocyte necrosis and apoptosis.

BACKGROUND: Because myocardial damage determines morbidity and outcomes in heart transplant rejection, assessment of total burden of myocardial damage is highly desirable. In addition to myocyte necrosis, programmed cell death, or apoptosis, has recently been shown to contribute to cardiac allograft rejection. In the present study, we noninvasively determined myocardial damage by antimyosin scintigraphy and compared it with necrotic and apoptotic myocardial damage in endomyocardial biopsy (EMB) specimens. METHODS AND RESULTS: Forty scintigraphic and histologic studies were simultaneously performed. Of these, 19 patients had no EMB evidence of allograft rejection (group I, International Society of Heart and Lung Transplantation [ISHLT] grade 0/4), 12 had mild rejection (group II, ISHLT grades 1A and 1B), and 9 had evidence of moderate allograft rejection (group III, ISHLT grades 2, 3A, and 3B). None of the biopsies demonstrated severe allograft rejection (ISHLT grade 4/4). The severity of global myocyte damage in 40 patients was assessed by antimyosin scintigraphy. Endomyocardial biopsies were performed in these patients within 48 hours of imaging study; biopsy specimens were characterized for presence of myocyte necrosis and apoptosis. Evidence of myocyte necrosis was observed in 9 (23%) of 40 EMB specimens. Nineteen EMB specimens of group I had no inflammation and no myocyte necrosis, 12 of group II specimens showed interstitial mononuclear cell infiltration (only) but no myocyte necrosis, and all 9 of group III specimens had evidence of cellular infiltration and myocyte damage. Myocyte necrosis was assessed by hematoxylin-eosin and trichrome staining of EMB specimens. On the other hand, apoptosis of myocytes, as assessed by TUNEL staining of DNA fragments, was seen in 22 (55%) of the 40 biopsy specimens: 47%, 58%, and 67% in groups I, II and III, respectively. Abnormal antimyosin scan findings, indicating presence of myocardial damage, were observed in 9 of the 19 patients in group I and in all patients in groups II and III. Although positive antimyosin scan results in group III patients are concordant with the presence of histologic myocardial necrosis, myocardial uptake of antimyosin antibodies in groups I and II (no apparent myocyte damage at light microscopic examination) could reflect either sampling error of the biopsy or ongoing apoptotic myocyte damage. CONCLUSIONS: Apoptosis of myocytes is frequently observed during cardiac allograft rejection. The presence of apoptotic myocytes in the absence of histologic rejection activity in patients with antimyosin uptake suggests that apoptosis could be an additional mechanism of transplant-associated myocardial damage.

Adult↗
PubMed2003

Genetic factors in the pathogenesis of primary biliary cirrhosis.

Current knowledge of the genetic basis of PBC is at best incomplete and at worst poor. Studies so far may be used as a guide to the pitfalls that await unwary investigators and also in deciding where to look and which genes or systems are most likely to yield informative results. The Human Genome Project has revealed a vast array of polymorphism that is too much to contemplate even with the best of current techniques. The crucial processes are the selection of candidates and study design. The strong genetic associations so far in PBC are with chromosomes 6p21.3 and 2q and include; HLA DRBI*08 haplotypes, CTLA4* G and IL1RN-IL1B haplotypes, CASP8, and nramp1. Many of the latter should be considered with caution until confirmed in independent series. Other associations with MBL, APOE and VDR remain to be confirmed. There are also several informative negatives, MMP3 and IL10 for example. It is unlikely that the only genes that influence disease susceptibility and progression in PBC are immunoregulatory genes concerned with T cell immunity. Recent studies indicate a new era for immunogenetics, when genes encoding all immune active proteins may be considered as candidates. One should not concentrate solely on the immune response as recent investigations of mannose binding lectin and apolipoprotein-E testify. One is only just beginning to understand the genetic basis of complex diseases like PBC. The key issues for future investigators are: defining the mechanisms where by self tolerance is broken, defining the mechanisms that determine the rate of disease progression, and identifying genetic markers to predict progression and malignancy. Assessing the genetic basis of variability in disease progression. The significant variation in rate of progression of PBC has led to the hypothesis that genes, in addition to contributing to disease susceptibility, may also determine the rate of disease progression. Several of the studies mentioned earlier have suggested associations between alleles at polymorphic loci and rate of progression . All studies performed to date, however, have been retrospective in nature. One problem inherent in such studies is that of definition of disease progression. One simple definition, that of histological progression to Scheuer stage IV disease , requires liver biopsy. The need to perform repeat biopsies raises ethical problems in cases where there is no other clinical indication. Studies of histologic progression in patients in the control arm of therapeutic trials represent one scenario where repeat biopsy would be indicated. However, the typical time course of such trials is 2 years, insufficient for meaningful assessment of disease progression and natural history, particularly in PBC where there is marked heterogeneity and, as a result, tissue sampling error. Yet, alternative systems for assessing disease progression, such as the Mayo prognostic score, lack sensitivity in any scenario other than existing advanced disease. Outlook for the future. Clinical observations support a significant genetic component to disease susceptibility. Elucidating predisposing genetic associations will markedly assist in understanding the pathophysiology of disease. Investigations to date have been restricted to various community-based case-control association studies, with well-recognized limitations. In future SNP maps and haplotype maps from the Human Genome Project will be available. Studies will require the collection of several well-characterized patients. To meet the required statistical power this will necessitate collaboration on a national and international scale. It is essential that these studies address the relationship between genes and disease progression. The possibility of identifying, in the early stages of disease, patients who are at elevated risk for more rapid progression, would have obvious clinical benefit in terms of patient management and therapy.

Genetic Predisposition to Disease↗
PubMedDate not supplied

Assessing uncertainty in DNA evidence caused by sampling effects.

Sampling error estimation in forensic DNA testimony was discussed. Is an estimate necessary and how should it be made? The authors find that all modern methods have areas of strength and weakness. The assessment of which is the 'best' is subjective and depends on the performance of the method, the type of problem (criminal work or paternity), the database size and availability of computing software and support. The authors preferred the highest posterior density approach for performance, however the other methods all have areas where their performance is adequate. For single-contributor stains normal approximation methods are suitable, also the bootstrap and the highest posterior density method. For multiple-contributor stains or other complex situations the match probability expressions become quite complex and it may not be possible to derive the necessary variance expressions. The highest posterior density or the bootstrap provide a better general method, with non-zero theta. The size-bias correction and the factor of 10 approaches may be considered acceptable by many forensic scientists as long as their limitations are understood.

DNA↗
PubMed2005

Fine needle aspiration cytology in the management of a parotid mass: a two centre retrospective study.

OBJECTIVES: There is a diversity of opinion regarding the role of fine needle aspiration cytology (FNAC) in the pre-operative evaluation of the parotid mass. This study further investigates the role of FNAC from the standpoint of the clinician attempting to resolve one or more clinical issues. METHODS: A retrospective study conducted at two UK Hospitals with no overlap of cytopathologists or surgeons. Patients undergoing parotidectomy at each institution were identified from Pathology department databases. The definitive histopathological diagnosis was compared with any pre-operative FNAC diagnosis. Cytology results were classified as suggestive, non-diagnostic, sampling error, or misleading. SETTING: The study was conducted in a District General Hospital and a University Teaching Hospital providing secondary care for each community. RESULTS: For the University Teaching Hospital the sensitivity in distinguishing malignant from benign disease was 79% (95% CI 61-97%) with a specificity 84% (95% CI 73-95%). However, three of eight patients with a primary parotid salivary gland malignancy were reported as having benign disease on FNAC. For the participating District General Hospital the sensitivity in distinguishing malignant from benign disease was 38% (95% CI 13-63%) and specificity 95% (95% CI 73-95%). CONCLUSIONS: Fine needle aspiration cytology does not reliably distinguish a benign from a malignant primary salivary gland neoplasm in the participating institutions. Where clinical teams use FNAC in an attempt to resolve this clinical problem, the results should be interpreted with caution and an ongoing audit of performance is required.

Biopsy, Fine-Needle↗
PubMed2005

Optical spectroscopy for the detection of dysplasia in Barrett's esophagus.

Patients with Barrett's esophagus (BE) undergo periodic endoscopic surveillance with multiple biopsy examinations in an attempt to identify dysplastic and early cancerous lesions at a time when intervention can be beneficial. However, this surveillance approach is hindered by low sampling yield, random sampling error, pathology-associated costs, and delay in diagnosis. Optical spectroscopy offers the potential to identify tissue pathology accurately in real time. The technique uses diagnostic molecular and/or microstructural information contained in light-tissue interactions such as fluorescence, elastic scattering, and inelastic (Raman) scattering. As an adjunct to endoscopy, optical spectroscopy has the capacity to enhance lesion detection in premalignant conditions such as BE. This article highlights the current status and future prospects of optical spectroscopy in BE.

Barrett Esophagus↗
PubMed2005

The use of optical coherence tomography in screening and surveillance of Barrett's esophagus.

Barrett's esophagus (BE) is defined as the presence of specialized intestinal metaplasia within the tubular esophagus. Recent studies suggest that performing endoscopic surveillance in patients with Barrett's esophagus is effective in preventing esophageal adenocarcinoma at an early stage. However, the accuracy of surveillance endoscopy is limited by sampling error and cost. Optical coherence tomography (OCT) is an optical analog of ultrasound, providing 10-microm resolution and real-time cross-sectional images of the luminal gastrointestinal tract. The literature describing the use of OCT in models of dysplasia and BE are reviewed. Three studies have examined the use of OCT in BE and models of dysplasia. These studies suggest that the currently achievable resolution combined with light-scattering properties of Barrett's mucosa is adequate to discern intestinal metaplasia and reliably detect high-grade dysplasia in patients with BE. Additional research to validate these findings is required.

Barrett Esophagus↗
PubMed2001

Rapid mutational declines of viability in Drosophila.

High rates of mildly deleterious mutation could cause the extinction of small populations, reduce neutral genetic variation and provide an evolutionary advantage for sex. In the first attempts to estimate the rate of mildly deleterious mutation, Mukai and Ohnishi allowed spontaneous mutations to accumulate on D. melanogaster second chromosomes shielded from recombination and selection. Viability of the shielded chromosomes appeared to decline rapidly, implying a deleterious mutation rate on the order of one per zygote per generation. These results have been challenged, however; at issue is whether Mukai and Ohnishi may have confounded viability declines caused by mutation with declines resulting from environmental changes or other extraneous factors. Here, using a method not sensitive to non-mutational viability changes, I reanalyse the previous mutation-accumulation (MA) experiments, and report the results of a new one. I show that in each of four experiments, including Mukai's two experiments, viability declines due to mildly deleterious mutations were rapid. The results give no support for the view that Mukai overestimated the declines. Although there is substantial variation in estimates of genomic mutation rates from the experiments, this variation is probably due to some combination of sampling error, strain differences and differences in assay conditions, rather than to failure to distinguish mutational and non-mutational viability changes.

Animals↗
PubMed2005

Comparative losses of quantitative and molecular genetic variation in finite populations of Drosophila melanogaster.

Quantitative genetic variation, the main determinant of the ability to evolve, is expected to be lost in small populations, but there are limited data on the effect, and controversy as to whether it is similar to that for near neutral molecular variation. Genetic variation for abdominal and sternopleural bristle numbers and allozyme heterozygosity were estimated in 23 populations of Drosophila melanogaster maintained at effective population sizes of 25, 50, 100, 250 or 500 for 50 generations, as well as in 19 highly inbred populations and the wild outbred base population. Highly significant negative regressions of proportion of initial genetic variation retained on inbreeding due to finite population size were observed for both quantitative characters (b = -0.67 +/- 0.14 and -0.58 +/- 0.11) and allozyme heterozygosity (b = -0.79 +/- 0.10), and the regression coefficients did not differ significantly. Thus, quantitative genetic variation is being lost at a similar rate to molecular genetic variation. However, genetic variation for all traits was lost at rates significantly slower than predicted by neutral theory, most likely due to associative overdominance. Positive, but relatively low correlations were found among the different measures of genetic variation, but their low magnitudes were attributed to large sampling errors, rather than differences in the underlying processes of loss.

Animals↗
PubMed2004

The growth of IQ among Estonian schoolchildren from ages 7 to 19.

The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others.

Adolescent↗
PubMed1990

Frequency distribution of Wuchereria bancrofti microfilariae in human populations and its relationships with age and sex.

This paper examines the effects of host age and sex on the frequency distribution of Wuchereria bancrofti infections in the human host. Microfilarial counts from a large data base on the epidemiology of bancroftian filariasis in Pondicherry, South India are analysed. Frequency distributions of microfilarial counts divided by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. Parameter estimates from the fits indicate a significant trend of decreasing overdispersion with age in the distributions above age 10; this pattern provides indirect evidence for the operation of density-dependent constraints on microfilarial intensity. The analysis also provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors (around 5% of the total negatives). This allows the construction of corrected mf age-prevalence curves, which indicate that the observed prevalence may underestimate the true figures by between 25% and 100%. The age distribution of mf-negative individuals in the population is discussed in terms of current hypotheses about the interaction between disease and infection.

Adolescent↗
PubMed1991

Frequency distribution of Brugia malayi microfilariae in human populations.

This study examines the effects of host age and sex on the frequency distribution of Brugia malayi infections in the human host. Microfilarial (mf) counts for a large data base on the epidemiology of brugian filariasis in Shertallai, Kerala, South India are analysed. Frequency distributions of microfilarial counts partitioned by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. This analysis provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors, allowing the construction of corrected mf age-prevalence curves, which indicate that the observed prevalence may under-estimate the true figures by between 18 and 47%. There is no evidence from these results for a decrease in the degree of over-dispersion of parasite frequency distributions with host age, such as might be produced by the acquired immunity to infection. This departure from the pattern in bancroftian filariasis (where there is evidence of such decreases in over-dispersion; Das et al. 1990) is discussed in terms of the long history of filariasis control (and consequently low infection prevalence) in Shertallai.

Adolescent↗
PubMed1999

Extending the p-plot: heuristics for multiple testing. HNRC group.

In the problem of large-scale multiple testing the p-plot is a graphically based competitor to the notoriously weak Bonferroni method. The p-plot is less stringent and more revealing in that it gives a gauge of how many hypotheses are decidedly false. The method is elucidated and extended here: the bootstrap reveals bias and sampling error in the usual point estimates, a bootstrap-based confidence interval for the gauge is given, as well as two acceptably powerful blanket tests of significance. Guidelines for use are given, and interpretational pitfalls pointed out, in the discussion of a case study linking premortem neuropsychological and postmortem neuropathologic data in an HIV cohort study.

Humans↗
PubMed2006

Mycotoxins in pet food: a review on worldwide prevalence and preventative strategies.

Mycotoxins contaminate cereal grains worldwide, and their presence in pet food has been a potential health threat to companion animals. Aflatoxins, ochratoxin A, and Fusarium mycotoxins have been found in both raw ingredients and final products of pet food around the globe. Aflatoxin, a hepatotoxin and carcinogen, has caused several food poisoning outbreaks in dogs, and aflatoxin content is regulated in pet food in many countries. Ochratoxin A and Fusarium mycotoxins including trichothecenes, zearalenone, and fumonisins may have chronic effects on the health of companion animals. Grain processing, sampling error, analytical methods, conjugated mycotoxins, storage conditions, and synergistic interactions are common challenges faced by the pet food industry. Food-processing techniques such as sieving, washing, pearling, ozonation, and acid-based mold inhibition reduce the mycotoxin content of cereal grains. Dietary supplementation with large neutral amino acids, antioxidants, and omega-3 polysaturated fatty acids as well as inclusion of mycotoxin-sequestering agents and detoxifying microbes may ameliorate the harmful effects of mycotoxins in contaminated pet food.

Aflatoxins↗
PubMed1998

Regression of hepatic fibrosis in hepatitis C with long-term interferon treatment.

Cirrhosis occurs in 20-50% of patients with hepatitis C and is thought to be irreversible. We describe two patients with cirrhosis secondary to hepatitis C in whom the extensive fibrosis and cirrhosis appeared to regress in response to treatment with interferon-alpha (IFN-alpha). Both patients were in the early stages of cirrhosis, class A in the Child-Pugh classification, total score 5 for each patient. Both responded fully to IFN-alpha and had normalization of all liver function tests and disappearance of hepatitis C viral RNA. Liver biopsies, performed before and after treatment, were coded unpaired by patient, combined with 21 liver biopsies from eight other patients with chronic hepatitis, and read independently by two pathologists using the Knodell scoring system. Knodell scores decreased from 14 to 3.5 and from 13.5 to 4 in these two patients. Cirrhosis and extensive fibrosis, present at baseline, were not present on follow-up liver biopsies, which were of sufficient size to reduce the likelihood of sampling error. We conclude that hepatic fibrosis and clinically early cirrhosis may be reversible in some patients with hepatitis C who respond to treatment with IFN-alpha.

Adult↗