The term apoptosis is proposed for a hitherto little recognized mechanism of controlled cell deletion, which appears to play a complementary but opposite role to mitosis in the regulation of animal cell populations. Its morphological features suggest that it is an active, inherently programmed phenomenon, and it has been shown that it can be initiated or inhibited by a variety of environmental stimuli, both physiological and pathological.The structural changes take place in two discrete stages. The first comprises nuclear and cytoplasmic condensation and breaking up of the cell into a number of membrane-bound, ultrastructurally well-preserved fragments. In the second stage these apoptotic bodies are shed from epithelial-lined surfaces or are taken up by other cells, where they undergo a series of changes resembling in vitro autolysis within phagosomes, and are rapidly degraded by lysosomal enzymes derived from the ingesting cells.Apoptosis seems to be involved in cell turnover in many healthy adult tissues and is responsible for focal elimination of cells during normal embryonic development. It occurs spontaneously in untreated malignant neoplasms, and participates in at least some types of therapeutically induced tumour regression. It is implicated in both physiological involution and atrophy of various tissues and organs. It can also be triggered by noxious agents, both in the embryo and adult animal.

Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics.

计量经济分析 = Econometric analysis

Publisher Summary The classification of cell death can be based on morphological or biochemical criteria or on the circumstances of its occurrence. Currently, irreversible structural alteration provides the only unequivocal evidence of death; biochemical indicators of cell death that are universally applicable have to be precisely defined and studies of cell function or of reproductive capacity do not necessarily differentiate between death and dormant states from which recovery may be possible. It has also proved feasible to categorize most if not all dying cells into one or the other of two discrete and distinctive patterns of morphological change, which have, generally, been found to occur under disparate but individually characteristic circumstances. One of these patterns is the swelling proceeding to rupture of plasma and organelle membranes and dissolution of organized structure—termed “coagulative necrosis.” It results from injury by agents, such as toxins and ischemia, affects cells in groups rather than singly, and evokes exudative inflammation when it develops in vivo. The other morphological pattern is characterized by condensation of the cell with maintenance of organelle integrity and the formation of surface protuberances that separate as membrane-bounded globules; in tissues, these are phagocytosed and digested by resident cells, there being no associated inflammation.

Cell death : the significance of apoptosis

Lessons from Hereditary Colorectal Cancer

Nonalcoholic fatty liver disease (NAFLD) is present in up to one third of the general population and in the majority of patients with metabolic risk factors such as obesity and diabetes. Insulin resistance is a key pathogenic factor resulting in hepatic fat accumulation. Recent evidence demonstrates NAFLD in turn, exacerbates hepatic insulin resistance and often precedes glucose intolerance. Once hepatic steatosis is established, other factors including oxidative stress, mitochondrial dysfunction, gut-derived lipopolysaccharide and adipocytokines, may promote hepatocellular damage, inflammation and progressive liver disease. Confirmation of the diagnosis of NAFLD can usually be achieved by imaging studies, however staging the disease requires a liver biopsy. NAFLD is associated with an increased risk of all-cause death, probably because of complications of insulin resistance such as vascular disease, as well as due to cirrhosis and hepatocellular carcinoma, which occurs in a minority of patients. NAFLD is also now recognized to account for a substantial proportion of patients previously diagnosed with 'cryptogenic cirrhosis'. Diabetes, obesity and the necroinflammatory form of NAFLD known as non-alcoholic steatohepatitis, are risk factors for progressive liver disease. Current treatment relies on weight loss and exercise, although various insulin-sensitizing medications appear promising. Further research is needed to identify which patients will achieve the most benefit from therapy.

Nonalcoholic fatty liver disease.

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.1840110114

The natural history of nonalcoholic steatohepatitis: A follow‐up study of forty‐two patients for up to 21 years

Necrosis and apoptosis: distinct modes of cell death with fundamentally different significance.

Background —Up to 15% of colorectal cancers are characterised by DNA microsatellite instability (MIN), shown by the presence of DNA replication errors (RERs). Aims —To identify pathological features that are discriminating for colorectal cancer (CRC) showing extensive MIN. Subjects —A prospective series of 303 patients with CRC and no family history of either familial adenomatous polyposis or hereditary non-polyposis colorectal cancer. Methods —DNA was extracted from fresh tissue samples and the presence of MIN was studied at nine loci that included TGFβRII, IGFIIR, and BAX. The 61 cases showing RERs were compared with 63 RER negative cases with respect to a comprehensive set of clinical and pathological variables. Predictive utility of the variables was tested by decision tree analysis. Results —Twenty seven patients with CRC showed extensive RERs (three loci or more) (RER+) and 34 had limited RERs only (28 = one locus; 6 = two loci) (RER+/−), yielding a bimodal distribution. RER+ cancers differed from RER− and RER+/− cases. Tumour type (adenocarcinoma, mucinous carcinoma, and undifferentiated carcinoma) (p=0.001), tumour infiltrating lymphocytes (p=0.001), and anatomical site (p=0.001) were the most significant of the discriminating variables. Algorithms developed by decision tree analysis allowed cases to be assigned to RER+ versus RER− and +/− status with a global sensitivity of 81.5%, specificity of 96%, and overall accuracy of 93%. Conclusion —Pathological examination of CRC allows assignment of RER+ status; assignment is specific and relatively sensitive. Conversely RER− and RER+/− CRC are indistinguishable.

https://gut.bmj.com/content/gutjnl/42/5/673.full.pdf

Morphology of sporadic colorectal cancer with DNA replication errors

Copyright @ Queen’s Printer and Controller of HMSO 2011. This work was produced by Pavey et al. under the terms of a commissioning contract issued by the Secretary of State for Health.

/pdf/the-clinical-effectiveness-and-cost-effectiveness-of-4hc1addiq9.pdf

The Clinical Effectiveness and Cost-Effectiveness of Exercise Referral Schemes: A Systematic Review and Economic Evaluation

Free to read at publisher

- Background

Exercise referral schemes (ERS) aim to identify inactive adults in the primary-care setting. The GP or health-care professional then refers the patient to a third-party service, with this service taking responsibility for prescribing and monitoring an exercise programme tailored to the needs of the individual.

 - Objective

To assess the clinical effectiveness and cost-effectiveness of ERS for people with a diagnosed medical condition known to benefit from physical activity (PA). The scope of this report was broadened to consider individuals without a diagnosed condition who are sedentary.

 - Data sources

MEDLINE; EMBASE; PsycINFO; The Cochrane Library, ISI Web of Science; SPORTDiscus and ongoing trial registries were searched (from 1990 to October 2009) and included study references were checked.

 - Methods

Systematic reviews: the effectiveness of ERS, predictors of ERS uptake and adherence, and the cost-effectiveness of ERS; and the development of a decision-analytic economic model to assess cost-effectiveness of ERS.

 - Results

Seven randomised controlled trials (UK, n = 5; non-UK, n = 2) met the effectiveness inclusion criteria, five comparing ERS with usual care, two compared ERS with an alternative PA intervention, and one to an ERS plus a self-determination theory (SDT) intervention. In intention-to-treat analysis, compared with usual care, there was weak evidence of an increase in the number of ERS participants who achieved a self-reported 90-150 minutes of at least moderate-intensity PA per week at 6-12 months' follow-up [pooled relative risk (RR) 1.11, 95% confidence interval 0.99 to 1.25]. There was no consistent evidence of a difference between ERS and usual care in the duration of moderate/vigorous intensity and total PA or other outcomes, for example physical fitness, serum lipids, health-related quality of life (HRQoL). There was no between-group difference in outcomes between ERS and alternative PA interventions or ERS plus a SDT intervention. None of the included trials separately reported outcomes in individuals with medical diagnoses. Fourteen observational studies and five randomised controlled trials provided a numerical assessment of ERS uptake and adherence (UK, n = 16; non-UK, n = 3). Women and older people were more likely to take up ERS but women, when compared with men, were less likely to adhere. The four previous economic evaluations identified suggest ERS to be a cost-effective intervention. Indicative incremental cost per quality-adjusted life-year (QALY) estimates for ERS for various scenarios were based on a de novo model-based economic evaluation. Compared with usual care, the mean incremental cost for ERS was £169 and the mean incremental QALY was 0.008, with the base-case incremental cost-effectiveness ratio at £20,876 per QALY in sedentary people without a medical condition and a cost per QALY of £14,618 in sedentary obese individuals, £12,834 in sedentary hypertensive patients, and £8414 for sedentary individuals with depression. Estimates of cost-effectiveness were highly sensitive to plausible variations in the RR for change in PA and cost of ERS.

 - Limitations

We found very limited evidence of the effectiveness of ERS. The estimates of the cost-effectiveness of ERS are based on a simple analytical framework. The economic evaluation reports small differences in costs and effects, and findings highlight the wide range of uncertainty associated with the estimates of effectiveness and the impact of effectiveness on HRQoL. No data were identified as part of the effectiveness review to allow for adjustment of the effect of ERS in different populations.

 - Conclusions

There remains considerable uncertainty as to the effectiveness of ERS for increasing activity, fitness or health indicators or whether they are an efficient use of resources in sedentary people without a medical diagnosis. We failed to identify any trial-based evidence of the effectiveness of ERS in those with a medical diagnosis. Future work should include randomised controlled trials assessing the cinical effectiveness and cost-effectivenesss of ERS in disease groups that may benefit from PA.
 - Funding

The National Institute for Health Research Health Technology Assessment programme.

Jeffrey Searle

Papers

The natural history of nonalcoholic steatohepatitis: A follow‐up study of forty‐two patients for up to 21 years

Necrosis and apoptosis: distinct modes of cell death with fundamentally different significance.

Morphology of sporadic colorectal cancer with DNA replication errors

The Clinical Effectiveness and Cost-Effectiveness of Exercise Referral Schemes: A Systematic Review and Economic Evaluation

The clinical effectiveness and cost-effectiveness of exercise referral schemes: A systematic review and economic evaluation