Biomedical subjects

A Spector

Publications and source records attributed to A Spector.

At least 19 recordsLinked to original sources

PubMed2006

Improved quality of life and cognitive stimulation therapy in dementia.

Quality of life (QoL) is now seen as a key outcome in many aspects of dementia care. In a recent randomized controlled trial of Cognitive Stimulation Therapy (CST) groups, significant improvements in self-reported QoL were identified as well as changes in cognitive function. This further analysis of results from the trial examines whether the changes in these two domains occurred independently, perhaps for different reasons, or whether the effect of treatment on QoL was mediated by the changes in cognition. In all, 201 people with dementia living in residential homes or attending day centres were assessed using the Quality of Life-Alzheimer's Disease (QOL-AD) scale and a range of measures of cognition, dementia level, mood, dependency and communication. Participants were randomized to receive an intervention programme of CST or to receive treatment as usual. The QoL-AD and other measures were repeated eight weeks later. At baseline, higher QoL in dementia was significantly correlated with lower levels of dependency and depression, but not with cognitive function or dementia severity. Improvement in quality of life was associated with being female, low quality of life at baseline, reduced depression and increased cognitive function. Changes in cognitive function mediated the effects of treatment in improving QoL. These results suggest that whilst QoL in dementia appears to be independent of level of cognitive function, interventions aimed at improving cognitive function can, nonetheless, have a direct effect on QoL.

Aged, 80 and over↗

PubMed2005

Reminiscence therapy for dementia.

BACKGROUND: Reminiscence Therapy (RT) involves the discussion of past activities, events and experiences with another person or group of people, usually with the aid of tangible prompts such as photographs, household and other familiar items from the past, music and archive sound recordings. Reminiscence groups typically involve group meetings in which participants are encouraged to talk about past events at least once a week. Life review typically involves individual sessions, in which the person is guided chronologically through life experiences, encouraged to evaluate them, and may produce a life story book. Family care-givers are increasingly involved in reminiscence therapy. Reminiscence therapy is one of the most popular psychosocial interventions in dementia care, and is highly rated by staff and participants. There is some evidence to suggest it is effective in improving mood in older people without dementia. Its effects on mood, cognition and well-being in dementia are less well understood. OBJECTIVES: The objective of the review is to assess the effects of reminiscence therapy for older people with dementia and their care-givers. SEARCH STRATEGY: The trials were identified from a search of the Specialised Register of the Cochrane Dementia and Cognitive Improvement Group on 4 May 2004 using the term "reminiscence". The CDCIG Specialized Register contains records from all major health care databases (MEDLINE, EMBASE, PsycLIT, CINAHL) and many ongoing trials databases and is regularly updated. We contacted specialists in the field and also searched relevant Internet sites. We hand-searched Aging and Mental Health, the Gerontologist, Journal of Gerontology, Current Opinion in Psychiatry, Current Research in Britain: Social Sciences, British Psychological Society conference proceedings and Reminiscence database. SELECTION CRITERIA: Randomised controlled trials and quasi-randomized trials of reminiscence therapy for dementia. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed trial quality. MAIN RESULTS: Five trials are included in the review, but only four trials with a total of 144 participants had extractable data. The results were statistically significant for cognition (at follow-up), mood (at follow-up) and on a measure of general behavioural function (at the end of the intervention period). The improvement on cognition was evident in comparison with both no treatment and social contact control conditions. Care-giver strain showed a significant decrease for care-givers participating in groups with their relative with dementia, and staff knowledge of group members' backgrounds improved significantly. No harmful effects were identified on the outcome measures reported. AUTHORS' CONCLUSIONS: Whilst four suitable randomized controlled trials looking at reminiscence therapy for dementia were found, several were very small studies, or were of relatively low quality, and each examined different types of reminiscence work. Although there are a number of promising indications, in view of the limited number and quality of studies, the variation in types of reminiscence work reported and the variation in results between studies, the review highlights the urgent need for more and better designed trials so that more robust conclusions may be drawn.

Aged↗

PubMed2003

Aroma therapy for dementia.

BACKGROUND: Complementary therapies have become more commonly used over the last decade and have been applied to a range of health problems, including dementia. Of these, aroma therapy is reported to be the most widely used in the British National Health Service (Lundie 1994) and might be of use for people with dementia for whom verbal interaction may be difficult and conventional medicine of only marginal benefit. Aroma therapy has been used for people with dementia to reduce disturbed behaviour (e.g. Brooker 1997), promote sleep (e.g. Wolfe 1996), and stimulate motivational behaviour (e.g. MacMahon 1998). OBJECTIVES: To assess the efficacy of aroma therapy as an intervention for people with dementia. SEARCH STRATEGY: The Cochrane Dementia and Cognitive Improvement Group's Specialized Register was searched on 29 October 2002 to find all relevant trials using the terms: aroma therap*, "aroma therap*", "complementary therap*", "alternative therap*" and "essential oil". The CDCIG Register contains records from all major health care databases and is updated regularly. Additionally, relevant journals were hand searched, and 'experts' in the field of complementary therapies and dementia contacted. SELECTION CRITERIA: All relevant randomized controlled trials (RCTs) were considered. A minimum length of trial and requirements for a follow-up were not included, and participants in included studies had a diagnosis of dementia of any type and severity. The review considered all trials using fragrance from plants defined as aroma therapy as an intervention with people with dementia. Several outcomes were considered in this review, including cognitive function, quality of life, and relaxation. DATA COLLECTION AND ANALYSIS: The titles and abstracts extracted by the searches were screened for their eligibility for potential inclusion in the review, which revealed 2 RCTs of aroma therapy for dementia. Neither of these had published results in a form that we could use. However, individual patient data from one trial were obtained (Ballard 2002) and additional analyses performed. Analysis of co-variance was used for all outcomes, using a random effects model. MAIN RESULTS: The additional analyses conducted revealed a statistically significant treatment effect in favour of the aroma therapy intervention on measures of agitation and neuropsychiatric symptoms. REVIEWER'S CONCLUSIONS: Aroma therapy showed benefit for people with dementia in the only trial that contributed data to this review, but there were several methodological difficulties with this study. More well designed large-scale RCTs are needed before conclusions can be drawn on the effectiveness of aroma therapy. Additionally, several issues need to be addressed, such as whether different aroma therapy interventions are comparable and the possibility that outcomes may vary for different types of dementia.

Aromatherapy↗

PubMed2003

Cognitive rehabilitation and cognitive training for early-stage Alzheimer's disease and vascular dementia.

BACKGROUND: Memory problems are a defining feature of the early stages of Alzheimer's disease (AD) and vascular dementia. Cognitive training and cognitive rehabilitation are specific approaches designed to address everyday memory difficulties. OBJECTIVES: The main aim was to evaluate the effectiveness and impact of cognitive training and cognitive rehabilitation interventions aimed at improving memory functioning for people in the early stages of Alzheimer's disease or vascular dementia. The two types of intervention were considered separately. SEARCH STRATEGY: The CDCIG Specialized Register, which contains records from MEDLINE, EMBASE, CINAHL, PsycINFO and many other databases, was searched on 9 April 2003. SELECTION CRITERIA: RCTs comparing cognitive rehabilitation or cognitive training interventions with comparison conditions, and reporting outcomes for the person with dementia and/or the family caregiver, were considered for inclusion. DATA COLLECTION AND ANALYSIS: Six studies reporting cognitive training interventions were included. Statistical analyses were conducted to provide an indication of intervention effect sizes. Data from ordinal scales was treated as continuous, and a fixed effects model was applied in calculating weighted mean differences and 95% confidence intervals. No studies were found that reported a fully individualised cognitive rehabilitation approach. MAIN RESULTS: None of the six studies reporting cognitive training interventions demonstrated any statistically significant effects in any domain, although there were indications of some modest, non-significant effects in various domains of cognitive functioning. REVIEWER'S CONCLUSIONS: The present findings do not provide strong support for the use of cognitive training interventions for people with early-stage AD or vascular dementia, although these findings must be viewed with caution due to the limited number of RCTs available and to the methodological limitations identified, and further well-designed trials would help to provide more definitive evidence. Due to a complete absence of RCTs evaluating an individualised cognitive rehabilitation approach, It is not possible at present to draw conclusions about the efficacy of individualised cognitive rehabilitation interventions for people with early-stage dementia, and further research is required in this area.

Alzheimer Disease↗

PubMed2001

Gene expression analysis of an H(2)O(2)-resistant lens epithelial cell line.

Gene expression patterns were examined in lens epithelial cells conditioned to grow in 125 microM hydrogen peroxide in order to define the protective mechanisms that may be involved in survival during oxidative stress. RNA was extracted from normal and hydrogen peroxide-resistant alphaTN4 mouse lens epithelial cells. Gene expression was evaluated using Differential Display (DD) and RT-PCR. Upregulation of mRNAs for antioxidant and cellular defense enzymes was observed. The highest elevation detected was a 14-fold increase in catalase in the hydrogen peroxide-resistant cells. Glutathione peroxidase, ferritin, and alphaB-crystallin were upregulated 2-fold, and reticulocalbin was upregulated 6-fold in the resistant cells. alphaA-crystallin was downregulated 5-fold, while aldose reductase and mitochondrial gene products were unchanged. Thus, in the alphaTN4 mouse lens cell line, long-term exposure to high levels of hydrogen peroxide elicited an upregulation of transcripts for enzymes involved in hydrogen peroxide degradation, metal binding, and chaperone function. Since mitochondrial gene transcription is sensitive to hydrogen peroxide, the presence of normal levels of mitochondrial transcripts, in this study, demonstrates the effectiveness of the antioxidant defense systems.

Animals↗

PubMed2001

The effect of aging on glutathione peroxidase-i knockout mice-resistance of the lens to oxidative stress.

Populations of control, C, and glutathione peroxidase-1 (GPx-1) knockout mice, K, were studied over a period of 2 years. No significant difference was observed between the C and K populations with respect to longevity, vitality, weight, lens biochemistry or morphology based on light and electron microscopy. It was concluded that under normal animal room barrier facilities, GPx-1 is not required. Furthermore, C and K lenses placed in organ culture and observed over a 24 hr period were indistinguishable. Organ cultured C lenses degraded medium H(2)O(2)levels at only a slightly greater rate than K lenses and this did not appear to change with age. However, tertiary butyl hydroperoxide (TBHP) was degraded less effectively by K lenses and this deficiency increased with age. No indication of change in redox non-protein SH (equivalent to GSH) status was observed between C and K whole lenses or epithelial cell fractions. With H(2)O(2)stress, the drop in C and K non-protein SH was comparable and there was little change with age. Examination of the impact of photochemical stress with 1.5 microM riboflavin and 4% O(2)upon choline transport indicated considerable damage with both C and K lenses, but little difference between the two populations until 1 or 2 years of age when the K lenses appear more vulnerable. With TBHP, the detrimental effect on the K lenses is greater and is observed earlier than with photochemical stress suggesting that the K lens membrane function is more susceptible to phospholipid hydroperoxide stress than are C lenses. Light and electron microscopy of the oxidative stressed lenses indicates significant damage which was generally somewhat greater in the K lenses. TBHP was a more potent oxidant than photochemically generated oxidants particularly at the anterior pole. The overall results suggest that under normal conditions, at any age, the lens does not require the presence of GPx-1 but depending on the type of oxidative stress, the enzyme may significantly contribute to its defense and this dependency may increase with age.

Aging↗

PubMed2001

ATP causes small heat shock proteins to release denatured protein.

Small heat-shock proteins (sHSPs) are a ubiquitous family of low molecular mass (15-30 kDa) stress proteins that have been found in all organisms. Under stress, sHSPs such as alpha-crystallin can act as chaperones binding partially denatured proteins and preventing further denaturation and aggregation. Recently, it has been proposed that the function of sHSPs is to stabilize stress-denatured protein and then act cooperatively with other HSPs to renature the partially denatured protein in an ATP-dependent manner. However, the process by which this occurs is obscure. As no significant phosphorylation of alpha-crystallin was observed during the renaturation, the role of ATP is not clear. It is now shown that ATP at normal physiological concentrations causes sHSPs to change their confirmation and release denatured protein, allowing other molecular chaperones such as HSP70 to renature the protein and renew its biological activity. In the absence of ATP, sHSPs such as alpha-crystallin are more efficient than HSP70 in preventing stress-induced protein aggregation. This work also indicates that in mammalian systems at normal cellular ATP concentrations, sHSPs are not effective chaperones.

Adenosine Triphosphate↗

PubMed2000

Reality orientation for dementia.

BACKGROUND: Reality Orientation (RO) was first described as a technique to improve the quality of life of confused elderly people, although its origins lie in an attempt to rehabilitate severely disturbed war veterans, not in geriatric work. It operates through the presentation of orientation information (eg time, place and person-related) which is thought to provide the person with a greater understanding of their surroundings, possibly resulting in an improved sense of control and self-esteem. There has been criticism of RO in clinical practice, with some fear that it has been applied in a mechanical fashion and has been insensitive to the needs of the individual. There is also a suggestion that constant relearning of material can actually contribute to mood and self-esteem problems. There is often little consistent application of psychological therapies in dementia services, so a systematic review of the available evidence is important in order to identify the effectiveness of the different therapies. Subsequently, guidelines for their use can be made on a sound evidence base. OBJECTIVES: To assess the evidence of effectiveness for the use of Reality Orientation (RO) as a classroom-based therapy on elderly persons with dementia. SEARCH STRATEGY: Computerised databases were searched independently by 2 reviewers entering the terms 'Reality Orientation, dementia, control, trial or study'. Relevant websites were searched and some handsearching was conducted by the reviewer. Specialists in the field were approached for undocumented material, and all publications found were searched for additional references. SELECTION CRITERIA: All randomised controlled trials (RCTs), and all controlled trials with some degree of concealment, blinding or control for bias (second order evidence) of Reality Orientation as an intervention for dementia were included. The criteria for inclusion/exclusion involved systematic assessment of the quality of study design and the risk of bias, using a standard data extraction form. A measure of cognitive and/or behavioural change was needed. DATA COLLECTION AND ANALYSIS: Data were extracted independently by both reviewers, using a previously tested data extraction form. Authors were contacted for data not provided in the papers. Psychological scales measuring cognitive and behavioural changes were examined. MAIN RESULTS: 6 RCTs were entered in the analysis, with a total of 125 subjects (67 in experimental groups, 58 in control groups). Results were divided into 2 subsections: cognition and behaviour. Change in cognitive and behavioural outcomes showed a significant effect in favour of treatment. REVIEWER'S CONCLUSIONS: There is some evidence that RO has benefits on both cognition and behaviour for dementia sufferers. Further research could examine which features of RO are particularly effective. It is unclear how far the benefits of RO extend after the end of treatment, but and it appears that a continued programme may be needed to sustain potential benefits.

Aged↗

PubMed2000

Reminiscence therapy for dementia.

BACKGROUND: Reminiscence Therapy (RT) has been defined as vocal or silent recall of events in a person's life, either alone, or with another person or group of people. It typically involves group meetings, at least once a week. in which participants are encouraged to talk about past events, often assisted by aids such as photos, music, objects and videos of the past. There is, often, little consistent application of psychological therapies in dementia services. A number of these 'therapies' were greeted with enthusiasm by health care practitioners in understimulating care environments. They were expected to work miracles and their 'failure' to do this has led to their widespread disuse. A systematic review of the available evidence is important in order to identify the effectiveness of the different therapies. Subsequently, guidelines for their use can be made on a sound evidence base. OBJECTIVES: RT involves groups of elderly people talking of past events, assisted by aids such as videos, pictures and archives, as a means of communicating and reflecting upon their life experiences. The objective of the review is to assess the effects of RT for dementia. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register, MEDLINE, PSYCHLIT, EMBASE, OMNI, BIDS, Dissertation Abstracts International, SIGLE and reference lists of relevant articles up to 1998, and we contacted specialists in the field. We also searched relevant internet sites and we handsearched Aging and Mental Health, the Gerontologist, Journal of Gerontology, Current Opinion in Psychiatry, Current Research in Britain: Social Sciences, British Psychological Society conference proceedings and Reminiscence database. SELECTION CRITERIA: Randomised controlled trials and quasi-randomised trials of RT for dementia in elderly people. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed trial quality. MAIN RESULTS: Two trials are included in the review, but only one trial with 15 participants had extractable data. The results were statistically non-significant for both cognition and behaviour. REVIEWER'S CONCLUSIONS: No firm conclusions could be reached regarding the effectiveness of RT for dementia. The review highlighted the urgent need for more systematic research in the area.

Dementia↗

PubMed2000

Aspirin for vascular dementia.

BACKGROUND: For patients with a diagnosis of vascular dementia there is evidence that aspirin is widely prescribed - in one study, completed by geriatricians and psychiatrists in the UK, 80% of patients with cognitive impairment (with vascular risk factors) were prescribed aspirin. However, a number of queries remain unanswered: Is there convincing evidence that aspirin benefits patients with vascular dementia? Does aspirin affect cognition or improve prognosis? In addition, does the risk of cerebral or gastric haemorrhage outweigh any benefit? The aim of this review is to assess the evidence of effectiveness of aspirin in those with a diagnosis of vascular dementia. OBJECTIVES: To assess the evidence of effectiveness of the use of aspirin for vascular dementia. SEARCH STRATEGY: Computerised databases were searched independently by two reviewers. In addition, relevant websites were searched and some journals were handsearched. Specialists in the field were approached for unpublished material and also any publications found were searched for additional references. SELECTION CRITERIA: All randomised controlled trials investigating the effect of aspirin for vascular dementia are included. Inclusion/exclusion of studies comprised systematic assessment of the quality of study design and the risk of bias. DATA COLLECTION AND ANALYSIS: Data were extracted independently by both reviewers, using a previously tested data extraction form and, where required, authors were contacted for data not provided in the papers. The aim was to evaluate data recorded via tools assessing cognitive and behavioural changes along with mortality, morbidity and institutionalisation data. MAIN RESULTS: One randomised controlled trial ( approximately approximately Meyer 1989 approximately approximately ) was included, and yielded data for analysis on a total of 70 patients. The only relevant outcome assessed in this trial was cognition. Change in cognitive outcome was towards being in favour of treatment. REVIEWER'S CONCLUSIONS: There is very limited evidence that aspirin is effective in treating patients with a diagnosis of vascular dementia. Further research is needed to assess the effect of aspirin on cognition, and also on additional outcomes such as behaviour, and quality of life. At present it is not possible to provide evidence for other queries regarding the use of aspirin for dementia (these are described in the Background section of this review).

Aspirin↗

PubMed2000

Investigation of the mechanism of action of microperoxidase-11, (MP11), a potential anti-cataract agent, with hydrogen peroxide and ascorbate.

The interaction of hydrogen peroxide, ascorbate and microperoxidase-11 (MP11), a ferriheme undecapeptide derived from cytochrome c, has been investigated using spectrophotometry, oxymetry, electron paramagnetic resonance (EPR), and mass spectroscopy techniques. It is shown that in 50 m M phosphate pH 7. 0-7.4 in the absence of other reactants H(2)O(2)induces a concentration-dependent decrease in absorption at the Soret band (399 nm) of the microperoxidase, with concomitant H(2)O(2)decomposition and oxygen evolution. The reaction causes irreversible heme degradation, concomitant with loss of enzymatic activity. Ascorbate effectively protects MP11 from degradation and inhibits oxygen evolution. At ascorbate concentrations greater than that of H(2)O(2), microperoxidase degradation is almost completely prevented. Mass spectrometry showed that H(2)O(2)oxidizes the microperoxidase to a monooxygenated product, which did not form if ascorbate was included in the reaction system. There appears to be a 1:1 relationship between H(2)O(2)degradation and ascorbate oxidation. EPR experiments revealed that an ascorbate radical was formed during the reaction. These reactions may be described by a scheme where a putative 'compound I' of the microperoxidase is reduced by ascorbate back to the original redox state (ferric) of the peroxidase in two one-electron steps, concomitantly with oxidation of the ascorbate to an ascorbate radical or in one two-electron transfer step forming dehydroascorbate. In the absence of ascorbate, the 'compound I' reacts further with the peroxide causing microperoxidase degradation and partial oxygen evolution. These observations are relevant to the interaction of ferrihemes with H(2)O(2)and ascorbic acid and may be pertinent for the potential application of MP11 as an anti-cataract agent.

Ascorbic Acid↗

PubMed2000

The effect of stress on the pattern of phosphorylation of alphaA and alphaB crystallin in the rat lens.

Previously, we have shown that phosphorylation of alpha crystallin (alpha) in rat lenses can be stimulated by oxidative stress. To better understand the biological functions of the stress-induced phosphorylation of the A and B chains of alpha (alphaA and alphaB), the normal and stress-induced phosphorylation pattern of these polypeptides in the rat lens has been investigated. With either alphaA or alphaB, there is only one phosphorylation site that is significantly affected, with widely different stresses, H(2)O(2)or elevation in free Ca(++)levels. However, the phosphorylation sites are markedly different for the two polypeptides, for alphaA being on Thr-4 in the N terminal region and with alphaB on Ser-59 in the central region of the polypeptide. The difference in the sequence in the two phosphorylation regions suggests that different phosphorylation systems are probably involved. This implies that the cellular function of the phosphorylation of alphaA and alphaB may be quite different.

Animals↗

PubMed2000

alpha-crystallin prevents irreversible protein denaturation and acts cooperatively with other heat-shock proteins to renature the stabilized partially denatured protein in an ATP-dependent manner.

alpha-Crystallin, a major lens protein of approximately 800 kDa with subunits of approximately 20 kDa has previously been shown to act as a chaperone protecting other proteins from stress-induced aggregation. Here it is demonstrated that alpha-crystallin can bind to partially denatured enzymes at 42-43 degrees C and prevent their irreversible aggregation, but cannot prevent loss of enzyme activity. However, the alpha-crystallin-bound enzymes regain activity on interaction with other chaperones. The data indicate that the re-activated enzymes are no longer associated with the alpha-crystallin, and ATP is required for re-activation. When inactive luciferase bound to alpha-crystallin was treated with reticulocyte lysate, a rich source of chaperones, up to 60% of the original luciferase activity could be recovered. Somewhat less re-activation was observed when the alpha-crystallin-bound enzyme was treated with heat-shock protein (HSP)70, HSP40, HSP60 and an ATP-generating system. Similar results were also obtained with citrate synthase. The overall results suggest that alpha-crystallin acts to stabilize denaturing proteins so that they can later be re-activated by other chaperones.

Adenosine Triphosphate↗

PubMed2000

Review: Oxidative stress and disease.

This communication briefly reviews aspects of oxidative stress and disease, particularly maturity onset cataract. The review considers a number of issues such as why lens and cataract research is important, what is oxidative stress, its relationship to disease and how does a tissue defend itself against such stress. Three diseases (chronic lung disease, diabetes and Alzheimer's disease) in which oxidative stress has differing roles are briefly discussed. The impact of oxidative stress upon the development of maturity onset cataract is considered and approaches are delineated which will establish the importance of such stress.

Animals↗

PubMed2000

Reality orientation for dementia: a systematic review of the evidence of effectiveness from randomized controlled trials.

The effectiveness of classroom reality orientation (RO) in dementia was evaluated by conducting a systematic literature review. This yielded 43 studies, of which 6 were randomized controlled trials meeting the inclusion criteria (containing 125 subjects.) Results were subjected to meta-analysis. Effects on cognition and behavior were significant in favor of treatment (cognition standardized mean difference [SMD] = -0.59; 95% confidence interval [CI] -0.95(-)-0.22; behavior SMD = -0.64, 95% CI = -1.20(-)-0.08). The evidence indicates that RO has benefits on both cognition and behavior for dementia sufferers. However, a continued program may be needed to sustain potential benefits. Future research should evaluate RO in well-designed multicenter trials.

Aged↗

PubMed2000

Development and characterization of an H2O2-resistant immortal lens epithelial cell line.

PURPOSE: To determine how nature would protect lens epithelial cells from H2O2 stress, an immortal murine lens epithelial cell line, alphaTN4-1, was subjected to gradually increasing H2O2 levels over a period of approximately 8 months. The resultant conditioned cells grew normally when exposed daily to 125 microM H2O2, whereas normal cells died within 9 hours. This communication describes changes in the cell biology of the conditioned cells that allowed them to remain viable. The manner in which critical biochemical parameters were affected in both conditioned and normal cells is also reported. METHODS: Conditioned cells were obtained by gradually increasing the concentration of H2O2 over a period of approximately 8 months, introducing an aliquot of H2O2 every 24 hours. A wide spectra of biological parameters were evaluated, including catalase, GSH peroxidase and other antioxidative enzyme activities, cell number and cell viability, non-protein thiol, ATP, transport systems, thymidine incorporation, and DNA cleavage. RESULTS: Surprisingly, the conditioned cells did not degrade the medium H2O2 more rapidly than normal cells. However, analyses of the antioxidative defenses indicated that catalase activity was increased 60-fold and glutathione peroxidase (GSH Px) approximately 2.7-fold. Glucose-6-phosphate dehydrogenase, GSH S-transferase, and GSSG reductase also had increased activity. Using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in situ trypsin digestion and matrix-assisted laser desorption/ionization mass spectrometry, a highly amplified doublet in the conditioned cell preparation was shown to be GSH S-transferase alpha-1 and alpha-2 isomers. Examination of key biochemical parameters indicated that while most such parameters in the conditioned cells showed marked decay in the first hour or so after stress, recovery was then observed and within a few hours, these parameters were back in the normal range. In contrast, damage in the normal cells was not repaired. The damage to DNA was shown to involve Fenton chemistry. In the presence of a metal ion chelator, normal cells survive H2O2 stress. CONCLUSIONS: The overall conclusion from this investigation is that nature has chosen to respond to the H2O2 stress by not only increasing the activity of enzymes degrading H2O2 but also the systems involved in repair, generation of reducing potential, and detoxification. All but one system of those evaluated appears to be permanently modified.

Adenosine Triphosphate↗

PubMed2000

DeltaFosB-induced cataract.

PURPOSE: The objective of this study was to investigate a possible relationship between posterior subcapsular cataract (PSC) formation and expression of the transcription factor DeltaFosB. METHODS: Western blot analysis was performed on bitransgenic NSE-tTA, TetOp-DeltaFosB, and single-transgenic NSE-tTA control mice to determine the pattern of DeltaFosB expression within the eye. Light and scanning electron microscopy and biochemical analyses were also performed. RESULTS: In mice expressing DeltaFosB, cataract developed that initially appeared to be posterior subcapsular and gradually matured to involve the entire lens. The enlarged posterior ends of developing secondary fibers curved away from the visual axis to form an elevated opaque posterior plaque. As a result, posterior suture formation did not occur. At a later time, the attenuated posterior capsule overlying the plaque ruptured and the lens nucleus subluxated into the vitreous. Retinal damage was also observed but only from postnatal day 65, a time when extensive lens degeneration had already occurred. DeltaFosB expression was observed well before the detection of morphologic change in both the lens and the retina. Within the lens, DeltaFosB expression was found in both the epithelium and fibers. The development of cataracts was a direct consequence of DeltaFosB expression and was not due to the disruption of an endogenous gene by transgene integration since cataracts could be prevented by silencing expression of DeltaFosB by feeding bitransgenic animals doxycycline (Dox). Moreover, cataracts were observed in bitransgenic mice derived from two independent TetOp-DeltaFosB founder lines but not in single NSE-tTA transgenic controls. Cataractogenesis was not a consequence of abnormal development, because mice conceived and raised on Dox to prevent expression of DeltaFosB also were subject to formation of PSC when expression of DeltaFosB was turned on in adult animals by removing Dox. Examination of biochemical parameters indicated that the earliest change observed was the disruption of calcium homeostasis with a significant increase in Ca(2+) influx, followed by a gradual but marked decrease in protein content. Significant changes in certain metabolic parameters and protein composition were also observed. CONCLUSIONS: The DeltaFosB-induced cataract in which the major morphologic early event was the disruption of normal posterior fiber formation, may be a good model for PSC. By identifying DeltaFosB-regulated target genes, it should be possible to achieve a better understanding of the molecular mechanisms through which PSC is formed.

Animals↗

PubMed1998

Okadaic acid-induced lens epithelial cell apoptosis requires inhibition of phosphatase-1 and is associated with induction of gene expression including p53 and bax.

It is well established that phosphorylation and dephosphorylation are key cellular events which regulate important metabolic activities such as gene expression, cell cycle progression, and apoptosis. The polyether fatty acid, okadaic acid has been shown previously to activate apoptosis in a variety of cell lines. Although this marine sponge toxin is known to inhibit protein phosphatase (PP)-2A and PP-1, it is not certain in most cases whether inhibition of PP-1 or PP-2A is necessary to activate apoptosis. Furthermore, it is not clear how inhibition of these phosphatases leads to apoptosis. Here we present evidence that inhibition of PP-2A by okadaic acid does not activate apoptosis in the lens system. However, when PP-1 is inhibited by okadaic acid, rabbit lens epithelial cells undergo rapid apoptosis. Associated with this process is the several-fold up-regulation of the tumor suppressor gene p53 and the pro-apoptotic gene bax at both mRNA and protein levels. Analyses of the temporal pattern of expression of the two genes reveal that the up-regulation is maximized in a few hours after treatment with okadaic acid, when the majority of the treated cells become committed to apoptosis. A brief treatment of the cells with a protein synthesis inhibitor can abolish okadaic acid-induced up-regulation of both P53 and Bax proteins. Concomitant with this inhibition, okadaic acid-induced apoptosis is also temporarily blocked. These results suggest that okadaic acid-induced expression of p53, bax, and other genes are necessary for the activation of the apoptotic programs in lens systems.

Animals↗