Mechanisms of apoptosis regulation by viral oncogenes in infection and tumorigenesis

Apoptosis mediated by the proapoptotic BCL-2 family members BCL-2-associated X-protein (BAX) and BCL-2 antagonist/killer (BAK) is part of the antiviral response at the cellular level to limit virus replication. Viruses, in turn, have evolved to encode antiapoptotic BCL-2 homologs (v-BCL-2s) to prevent the premature death of the infected host cell to sustain virus replication. These same v-BCL-2 proteins cooperate with loss of retinoblastoma protein and p53 tumor suppressor function, by inactivating the BAX and BAK apoptotic pathway to promote epithelial solid tumor growth and resistance to chemotherapy. Analogously to infected cells, failure of apoptosis in tumors permits the survival of abnormal, damaged cells displaying chromosome instability that may further promote tumor progression. Thus, both infected cells and tumor cells require inhibition of the apoptotic host defense mechanism, the insights from which can be exploited for therapy development.

Usual interstitial pneumonia

Usual interstitial pneumonia (UIP) is a distinct histological lesion observed in idiopathic pulmonary fibrosis (IPF), but can be found in other etiologies. The diagnosis of UIP can be established by surgical lung biopsy or by high resolution thin section computed tomographic scans (provided the radiographic features are classical). Historically, patients labeled as "IPF'' encompassed a group of disorders including UIP as well as other idiopathic interstitial pneumonias, which differ from UIP in prognosis and responsiveness to therapy. Current recommendations from international consensus statements restrict the term IPF to patients with idiopathic UIP. The inciting cause(s) and pathogenesis of UIP have not been elucidated, but alveolar epithelial cell injury and dysregulation or altered phenotypic expression of fibroblasts are key elements. Inflammatory cells may play minor roles in initiating or propagating the fibrotic process. The prognosis of UIP is poor. Mean survival following diagnosis approximates 3 years. Current therapies are of unproven value. Corticosteroids or immunosuppressive agents have been most often used, but data affirming benefit are lacking. Single-lung transplantation is a viable option for patients failing medical therapy. Novel therapeutic strategies based upon inhibiting fibroproliferation or enhancing alveolar reepithelialization are desperately needed. In this article, we discuss diagnostic criteria for UIP (both histopathological and radiographic), natural history and clinical course, and therapeutic approaches (both current and future).

A comparison of four methods of tonometry: method agreement and interobserver variability

AIM

To compare the inter-method agreement in intraocular pressure (IOP) measurements made with four different tonometric methods.

METHODS

IOP was measured with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT) in a randomised order in one eye of each of 105 patients with ocular hypertension or glaucoma. Three measurements were made with each method, and by each of two independent GAT observers. GAT interobserver and tonometer inter-method agreement was assessed by the Bland-Altman method. The outcome measures were 95% limits of agreement for IOP measurements between GAT observers and between tonometric methods, and 95% confidence intervals for intra-session repeated measurements.

RESULTS

The mean differences (bias) in IOP measurements were 0.4 mm Hg between GAT observers, and 0.6 mm Hg, 0.1 mm Hg, and 0.7 mm Hg between GAT and Tono-Pen, OBF, and NCT, respectively. The 95% limits of agreement were smallest (bias +/-2.6 mm Hg) between GAT observers, and larger for agreement between the GAT and the Tono-Pen, OBF, and NCT (bias +/-6.7, +/-5.5, and +/-4.8 mm Hg, respectively). The OBF and NCT significantly underestimated GAT measurements at lower IOP and overestimated these at higher IOP. The repeatability coefficients for intra-session repeated measurement for each method were +/-2.2 mm Hg and +/-2.5 mm Hg for the GAT, +/-4.3 mm Hg for the Tono-Pen, +/-3.7 mm Hg for the OBF, and +/-3.2 mm Hg for the NCT.

CONCLUSIONS

There was good interobserver agreement with the GAT and moderate agreement between the NCT and GAT. The differences between the GAT and OBF and between the GAT and Tono-Pen probably preclude the OBF and Tono-Pen from routine clinical use as objective methods to measure IOP in normal adult eyes.

The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry

AIMS

To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT).

METHODS

CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis.

RESULTS

A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 mum increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p< or = 0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects.

CONCLUSION

IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen.

Effects of physical activity intensity, frequency, and activity type on 10-y weight change in middle-aged men and women

BACKGROUND

Increased physical activity is often recommended for weight maintenance and loss.

OBJECTIVE

To examine how intensity, frequency, and type of recreational physical activity are associated with weight gain attenuation over a 10-y period.

PARTICIPANTS

Over 15 000 adults between 53 and 57 y living in western Washington State recruited between 2000 and 2002.

MEASUREMENTS

Self-reported measures of physical activity (using a questionnaire), height, and weight.

METHODS

We examined associations between physical activity and weight change after age 45 y. All analyses controlled for age at baseline, weight at age 45 y (continuous), diet, education, smoking, and weight change between ages 30 and 45 y, and were stratified by sex and body mass index (BMI) at age 45 y (normal weight, overweight, or obese).

RESULTS

Increasing MET-hours and sessions per week of high-, moderate- and low-intensity activities over 10 y were inversely related to weight gain after age 45 y. Generally, associations were stronger for women than for men and for obese compared to normal weight or overweight individuals. Obese women and men who participated in 75-100 min per week of fast walking gained 9 and 5 pound less than nonwalkers, respectively, and lesser amounts in normal weight and overweight women and men. Jogging, aerobics, and fast cycling were associated with weight gain attenuation in most sex and age 45 y BMI groups, while slow walking, swimming, and weight lifting were not.

CONCLUSIONS

In this free-living population, long-term, regular physical activity, particularly common activities carried out at a moderate intensity such as walking, prevented some of the weight gain associated with aging.

Transanal endoscopic microsurgery: a viable operative alternative in selected patients with rectal lesions

BACKGROUND

Local excision of rectal lesions is being increasingly undertaken, especially in those unfit for major surgery. The traditional transanal approach is often cumbersome and limited to low and mid rectal lesions. Transanal endoscopic microsurgery (TEMS) is being used to excise both benign and malignant rectal lesions, including those in the upper rectum.

METHODS

Prospective analysis of all patients undergoing a TEMS excision between January 1997 and December 2000 in a specialized colorectal unit.

RESULTS

Forty patients underwent a TEMS resection, with a mean age of 72 years (SD, 10 years). The mean distance of the lesions from the anal verge was 9.8 cm (SD, 3.1 cm). In 24 patients, the lesion was located >or=10 cm from the anal verge, making them unsuitable for traditional transanal resection. The mean operative time was 91 minutes (SD, 34 minutes), and the mean postoperative stay was 3 days (SD, 1.5 days). No mortality was associated with the procedure, and there was minimal morbidity in 15%. There has been no recurrence in the 18 patients who had a malignant lesion excised.

CONCLUSIONS

The TEMS operating system provides the surgeon with a suitable alternative for the resection of benign and malignant rectal neoplasms in selected patients. It has the advantage of providing visual clarity of the operative field, allowing more precise dissection and a minimally invasive approach to mid and upper rectal lesions. There has been no mortality and minimal morbidity. We advocate its inclusion as part of a colorectal surgeon's operative armamentarium for these selected cases.

Cytoskeletal modulation of electrical and mechanical activity in cardiac myocytes

The cardiac myocyte has an intracellular scaffold, the cytoskeleton, which has been implicated in several cardiac pathologies including hypertrophy and failure. In this review we describe the role that the cytoskeleton plays in modulating both the electrical activity (through ion channels and exchangers) and mechanical (or contractile) activity of the adult heart. We focus on the 3 components of the cytoskeleton, actin microfilaments, microtubules, and desmin filaments. The limited visual data available suggest that the subsarcolemmal actin cytoskeleton is sparse in the adult myocyte. Selective disruption of cytoskeletal actin by pharmacological tools has yet to be verified in the adult cell, yet evidence exists for modulation of several ionic currents, including I(CaL), I(Na), I(KATP), I(SAC) by actin microfilaments. Microtubules exist as a dense network throughout the adult cardiac cell, and their structure, architecture, kinetics and pharmacological manipulation are well described. Both polymerised and free tubulin are functionally significant. Microtubule proliferation reduces contraction by impeding sarcomeric motion; modulation of sarcoplasmic reticulum Ca(2+) release may also be involved in this effect. The lack of effect of microtubule disruption on cardiac contractility in adult myocytes, and the concentration-dependent modulation of the rate of contraction by the disruptor nocodazole in neonatal myocytes, support the existence of functionally distinct microtubule populations. We address the controversy regarding the stimulation of the beta-adrenergic signalling pathway by free tubulin. Work with mice lacking desmin has demonstrated the importance of intermediate filaments to normal cardiac function, but the precise role that desmin plays in the electrical and mechanical activity of cardiac muscle has yet to be determined.

Peroxidation of docosahexaenoic acid is responsible for its effects on I TO and I SS in rat ventricular myocytes

1 Exposure to docosahexaenoïc acid (DHA), a long-chain polyunsaturated fatty acid, is known to block several ionic currents such as the transient outward current I(TO). It has also been reported to activate certain potassium channels. It has been suggested that these effects, observed in single-cell experiments, participate in the antiarrhythmic properties of these compounds in vivo. 2 DHA is highly prone to peroxidation. To investigate the influence peroxidation may have on the effects of DHA on ion channels, we studied I(TO) and the steady-state outward current I(SS) in isolated rat ventricular myocytes under ruptured whole-cell patch-clamp conditions. 3 A measure of 10 micro M DHA alone reduced I(TO), evoked by a pulse to +70 mV, by 74.8+/-10.8% (n=7) and activated a delayed outward current with kinetic properties different from I(SS). 4 When an antioxidant, alpha-tocopherol (1 micro M), was added together with DHA, the blockade of I(TO) was reduced to 38.5+/-7.7% (n=8) and the delayed outward current was not activated. alpha-Tocopherol alone had no effect on these currents. 5 When an oxidant, hydrogen peroxide (1 micro M), was applied together with DHA, the blockade of I(TO) was almost complete (98.4+/-1.0%, n=7) and a large delayed outward current was activated. A measure of 1 micro M hydrogen peroxide alone had no effect on these currents. 6 Measurements of nonperoxidized DHA in experimental solutions confirmed the negative relation between DHA concentration and the effects on the currents. 7 We conclude that rather than DHA itself, it is the peroxidation products of DHA that block I(TO) and activate a delayed outward current in in vitro single-cell experiments. These findings have important implications for the extrapolation of in vitro experimental findings to the antiarrhythmic effects of DHA in vivo because, in vivo, peroxidation of DHA is unlikely to occur.