Corneal endothelial response to induced myopia in the chicken

Purpose: To investigate the role of corneal endothelial surface enlargement in the chicken myopia model in inducing corneal endothelial changes. Methods: Lid suture was performed on one eye of 1-day-old cockerels. Five chickens were killed at 1 week, and four chickens killed at each of 3 weeks, 6 weeks, and 10 weeks postnatal. The endothelial morphology was obtained by flat mounting the endothelial surface and the subsequent digitisation. Comparisons were undertaken between the control unsutured eye and the lid-sutured eye endothelium, and between the central endothelial areas compared to the peripheral endothelial areas in both the myopic and the normal corneas. Calculation of the contribution to the endothelial change by hypertrophy and mitosis were calculated using Bahn's formula. Results: Total endothelial surface area increased significantly over time in the myopic model compared to control eyes but the mean cell area of endothelial cells remained the same for both the enlarged myopic endothelial surface area and in the normal controls. Sampling from the central and the peripheral corneal endothelial surface also disclosed no difference. The mean cell area did increase steadily with age but was the same for both normal and myopic corneas. Conclusions: It would appear that there are equal contributions from hypertrophy and mitosis in the myopic group and the normal corneal group with a slightly increasing trend towards mitotic activity in the myopic corneal endothelial layer.

UV-induced hyperphosphorylation of replication protein a depends on DNA replication and expression of ATM protein

Exposure to DNA-damaging agents triggers signal transduction pathways that are thought to play a role in maintenance of genomic stability. A key protein in the cellular processes of nucleotide excision repair, DNA recombination, and DNA double-strand break repair is the single-stranded DNA binding protein, RPA. We showed previously that the p34 subunit of RPA becomes hyperphosphorylated as a delayed response (4-8 h) to UV radiation (10-30 J/m(2)). Here we show that UV-induced RPA-p34 hyperphosphorylation depends on expression of ATM, the product of the gene mutated in the human genetic disorder ataxia telangiectasia (A-T). UV-induced RPA-p34 hyperphosphorylation was not observed in A-T cells, but this response was restored by ATM expression. Furthermore, purified ATM kinase phosphorylates the p34 subunit of RPA complex in vitro at many of the same sites that are phosphorylated in vivo after UV radiation. Induction of this DNA damage response was also dependent on DNA replication; inhibition of DNA replication by aphidicolin prevented induction of RPA-p34 hyperphosphorylation by UV radiation. We postulate that this pathway is triggered by the accumulation of aberrant DNA replication intermediates, resulting from DNA replication fork blockage by UV photoproducts. Further, we suggest that RPA-p34 is hyperphosphorylated as a participant in the recombinational postreplication repair of these replication products. Successful resolution of these replication intermediates reduces the accumulation of chromosomal aberrations that would otherwise occur as a consequence of UV radiation.

Immune-derived opioids and peripheral antinociception

1. Recent findings have suggested a significant involvement of the immune system in the control of pain. Immune cells contain opioid peptides that are released within inflamed tissue and act at opioid receptors on peripheral sensory nerve endings. It is also apparent that different types of lymphocytes contain P-endorphin, memory T cells containing more beta -endorphin than naive cells. 2. These findings highlight an integral link between immune cell migration and inflammatory pain, The present review highlights immune system involvement in the site-directed control of inflammatory pain. 3. Full-length mRNA transcripts for opioid precursor proteins are expressed in immune cells. Increased expression of pro-opiomelanocortin mRNA and beta -endorphin has been demonstrated in stimulated lymphocytes and lymphocytes from animals with inflammation. 4. Cytokines and corticotropin-releasing factor (CRF) release opioids from immune cells, Potent peripheral analgesia due to direct injection of CRF can be blocked by antagonists to CRF, antibodies to opioid peptides, antisense to CRF and opioid receptor-specific antagonists. The release of opioid peptides from lymphocytes is calcium dependent and opioid receptor specific. Furthermore, endogenous sources of opioid peptides produce potent analgesia when implanted into the spinal cord. 5. Activated immune cells migrate directly to inflamed tissue using cell adhesion molecules to adhere to the epithelial surface of the vasculature in inflamed tissue. Lymphocytes that have been activated can express opioid peptides, Memory type T cells that contain opioid peptides are present within inflamed tissue; naive cells are not present in inflamed tissue and do not contain opioid peptides, Inhibiting the migration of memory type T cells into inflamed tissue by blocking selectins results in reduced numbers of beta -endorphin containing cells, a reduced quantity of beta -endorphin in inflamed paws and reduced stress- and CRF-induced peripheral analgesia. 6. Immunosuppression is associated with increased pain in patients. Moreover, immunosuppression results in decreased lymphocyte numbers as well as decreased analgesia in animal models.

Irradiation-induced oral candidiasis in an experimental murine model

The aim of this experiment was to establish a mouse model of irradiation-induced oral candidiasis and to explore the cellular populations and mechanisms by which the infection is cleared from the oral mucosa. BALB/c mice received irradiation to the head and neck equivalent to 800 Rad using a Cobalt 60 gamma source. Both irradiated and non-irradiated mice were infected orally with 1 X 10(8) Candida albicans yeasts. Compared with untreated controls, irradiated animals developed a more severe infection of longer duration, with hyphae penetrating the oral mucosa. Monoclonal antibody depletion of CD4(+) but not CD8(+) T cells from the systemic circulation prolonged the infection in irradiated mice, but not in controls. Supernatants of submandibular and superficial cervical lymph node cultures from irradiated animals demonstrated significantly higher titers of interleukin-12, but similar levels of interferon-gamma compared with controls. Screening for cytokine production by an RNase protection assay detected only macrophage migration inhibition factor in irradiated and non-irradiated oral tissues from day 8 onwards. The results of this study demonstrate a requirement for CD4(+) T cells in the recovery from oral candidiasis induced by head and neck irradiation in mice, and are consistent with a role for Th-1-type cytokines in host resistance.

Improving pain management by nurses: A pilot peer intervention program

Significant pain continues to be reported by many hospitalized patients despite the numerous and varied educational programs developed and implemented to improve pain management. A theoretically based Peer Intervention Program was designed from a predictive model to address nurses' beliefs, attitudes, subjective norms, self-efficacy, perceived control and intentions in the management of pain with p.r.n. (as required) narcotic analgesia. The pilot study of this program utilized a quasi-experimental pre-post test design with a patient intervention, nurse and patient intervention and control conditions consisting of 24, 18 and 19 nurses, respectively. One week after the intervention, significant differences were found between the nurse and patient condition and the two other conditions in beliefs, self-efficacy, perceived control, positive trend in attitudes, subjective norms and intentions. The most positive aspects of the program were supportive interactive discussions with peers and an awareness and understanding of beliefs and attitudes and their roles in behavior.

Determinants of nurses' intention to administer opioids for pain relief

A statewide cross-sectional survey was conducted in Australia to identify the determinants of registered nurses' intention to administer opioids to patients with pain. Attitudes, subjective norms and perceived control, the key determinants of the Theory of Planned Behavior, were found to independently predict nurses' intention to administer opioids to these patients. Perceived control was the strongest predictor. Nurses reported positive overall attitudes towards opioids and their use in pain management. However, many negative attitudes were identified; for example, administering the least amount of opioid and encouraging patients to have non-opioids rather than opioids for pain relief. The findings related to specific attitudes and normative pressures provide insight into registered nurses' management of pain for hospitalized patients and the direction for educational interventions to improve registered nurses' administration of opioids for pain management.

Changes in motor planning of feedforward postural responses of the trunk muscles in low back pain

Changes in trunk muscle recruitment have been identified in people with low-back pain (LBP). These differences may be due to changes in the planning of the motor response or due to delayed transmission of the descending motor command in the nervous system. These two possibilities were investigated by comparison of the effect of task complexity on the feedforward postural response of the trunk muscles associated with rapid arm movement in people with and without LBP. Task complexity was increased by variation of the expectation for a command to either abduct or flex the upper limb. The onsets of electromyographic activity (EMG) of the abdominal and deltoid muscles were measured. In control subjects, while the reaction time of deltoid and the superficial abdominal muscles increased with task complexity, the reaction time of transversus abdominis (TrA) was constant. However, in subjects with LBP, the reaction time of TrA increased along with the other muscles as task complexity was increased. While inhibition of the descending motor command cannot be excluded, it is more likely that the change in recruitment M of TrA represents a more complex change in organisation of the postural response.

Mechanisms of drought-induced population decline in an endangered wallaby

The bridled nailtail wallaby is restricted to one locality in central Queensland, Australia. The population declined severely during a major drought between 1991 and 1995. We investigated age-specific covariates of survival and proximate causes of mortality from 1994 to 1997, using mark-recapture and radio-tagging techniques at two study sites. Using a matrix population model, we also modelled the effect of drought on age-specific survival and the intrinsic rate of population increase,;,. The only significant covariate of survival for adults was a measure of health unrelated to drought. Rainfall, food, predator activity, year, sex and habitat were not associated with variation in adult survival. Juvenile survival was negatively affected by drought, and predation was the proximate cause of most juvenile deaths. The matrix projection model showed that the observed juvenile survivorship during the drought was low enough to have produced a population decline, although fecundity and survival of other age classes was high throughout the study. (C) 2001 Elsevier Science Ltd. All rights reserved.

Emotional distress induced rhabdomyolysis in an individual with carnitine palmitolytransferase deficiency

A 48-year-old male patient with underlying CPT II enzyme deficiency is described. Emotional stress appeared to precipitate recurrent myalgias, rhabdomyolysis and reversible renal impairment over a 40-year period. Our search of the English literature indicates this to be the first time that the emotional stress has been documented to precipitate the CPT II syndrome. Although the pathogenesis of this syndrome has yet to be established, existing knowledge is briefly reviewed and the likely metabolic and neuroendocrine mechanisms which link emotional stress to muscle metabolism are examined. These mechanisms influence the extent of lipolysis or glycolysis that occurs during the process of muscle ATP generation. It is suggested that neuroendocrine and other stress related changes which favour lipolysis over glycolysis adversely effect muscle energy metabolism in patients whose mitochondria are deficient in CPT II enzyme. Possible treatment strategies are those that favour glycolysis over fatty acid metabolism and include a variety of ways of modulating sympathetic and parasympathetic tone. The use of carbohydrate supplementation P-blockers and anxiolytic agents is discussed.

Increased susceptibility to streptozotocin-induced beta-cell apoptosis and delayed autoimmune diabetes in alkylpurine-DNA-N-glycosylase-deficient mice

Type I diabetes is thought to occur as a result of the loss of insulin-producing pancreatic beta cells by an environmentally triggered autoimmune reaction. In rodent models of diabetes, streptozotocin (STZ), a genotoxic methylating agent that is targeted to the beta cells, is used to trigger the initial cell death. High single doses of STZ cause extensive beta -cell necrosis, while multiple low doses induce limited apoptosis, which elicits an autoimmune reaction that eliminates the remaining cells. We now show that in mice lacking the DNA repair enzyme alkylpurine-DNA-N-glycosylase (APNG), beta -cell necrosis was markedly attenuated after a single dose of STZ. This is most probably due to the reduction in the frequency of base excision repair-induced strand breaks and the consequent activation of poly(ADP-ribose) polymerase (PARP), which results in catastrophic ATP depletion and cell necrosis. Indeed, PARP activity was not induced in A-PNG(-/-) islet cells following treatment with STZ in vitro. However, 48 h after STZ treatment, there was a peak of apoptosis in the beta cells of APNG(-/-) mice. Apoptosis was not observed in PARP-inhibited APNG(+/+) mice, suggesting that apoptotic pathways are activated in the absence of significant numbers of DNA strand breaks. Interestingly, STZ-treated APNG(-/-) mice succumbed to diabetes 8 months after treatment, in contrast to previous work with PARP inhibitors, where a high incidence of beta -cell tumors was observed. In the multiple-low-dose model, STZ induced diabetes in both APNG(-/-) and APNG(-/-) mice; however, the initial peak of apoptosis was 2.5-fold greater in the APNG(-/-) mice. We conclude that APNG substrates are diabetogenic but by different mechanisms according to the status of APNG activity.

The effects of pregnancy on myelin basic protein-induced experimental autoimmune encephalomyelitis in Lewis rats: Suppression of clinical disease, modulation of cytokine expression in the spinal cord inflammatory infiltrate and suppression of lymphocyte p

Problem: The present study was performed to explore the effects of pregnancy on experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats by inoculation with myelin basic protein (MBP) (MBP-EAE). Method of study: MBP-EAE was induced in pregnant and non-pregnant rats and severity of disease evaluated. Serum from pregnant and non-pregnant rats was used in standard lymphocyte proliferation assays. Real-time polymerase chain reaction (PCR) was used to investigate the expression of cytokine mRNA in the inflammatory cells obtained from the spinal cord of rats on day 15 after inoculation. Results: Pregnant rats developed less severe disease than non-pregnant rats. Serum from pregnant rats suppressed the proliferation of T lymphocytes in response to MBP. There was significantly increased expression of IL-4. IL-10 and TNF-alpha mRNA in the spinal cord infiltrate of pregnant rats. Conclusion: Circulating humoral factors and alteration in cytokine production by inflammatory cells may contribute to the suppression of EAE in pregnant rats.

A cross-sectional study of the association between Heberden's nodes, radiographic osteoarthritis of the hands, grip strength, disability and pain

Objective: To describe the associations between hand osteoarthritis (OA), pain and disability in males and females and to further validate the Australian/Canadian CA hand index (AUSCAN LK3.0). Design: Cross-sectional study of 522 subjects from 101 Tasmanian families (males N=174, females N=348). Hand OA was assessed by two observers using the Altman atlas for joint space narrowing and osteophytes at distal interphalangeal and first carpometacarpal joints as well as a score for Heberden's nodes based on hand photography. Hand pain and function were assessed by the AUSCAN LK3.0 and grip strength by dynamometry in both hands on two occasions. Results: The prevalence of hand CA was high in this sample at 44-71% (depending on site). Pain and dysfunction increased with age while grip strength decreased (all P <0.001). All three measures were markedly worse in women, even after taking the severity of arthritis into account. Hand CA explained 5.7-10% of the variation in function, grip strength and pain scores, even after adjustment for age and sex. Further adjustment suggested that the osteoarthritic associations with function and grip strength were largely mediated by pain. Severity of disease was more strongly associated with these scores than presence or absence. Lastly, the AUSCAN LK3.0 showed a comparable association to grip strength with structural damage providing further evidence of index validity. Conclusions: Hand CA at these two sites makes substantial contributions to hand function, strength and pain. The associations with function and strength measures appear mediated by pain. Gender differences in all three measures persist after adjustment for variation in age and CA severity indicating that factors apart from radiographic disease are responsible. (C) 2001 OsteoArthritis Research Society International.