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Biomedical subjects

D L Evans

Publications and source records attributed to D L Evans.

At least 73 records · Page 4Linked to original sources
PubMed1999

Depression in the medical setting: biopsychological interactions and treatment considerations.

This article examines depression in 6 medical conditions: coronary artery disease (CAD), cancer, human immunodeficiency virus (HIV) infection, Parkinson's disease, pain, and the sex hormone changes of aging. Research is beginning to define specific biological and psychological mechanisms underlying the adverse interactions between depression and these medical conditions. Antidepressant medications, psychosocial therapies, and hormonal manipulations are effective in reducing depressive symptoms. Specific psychosocial interventions may increase longevity in CAD and cancer and may enhance quality of life in HIV infection. Newer antidepressants appear to be safer and better tolerated than older agents for medically ill patients, but do not appear to be as effective for neuropathic pain. Dopamine agonists may benefit depression associated with Parkinson's disease. Hormone replacement therapy may improve subsyndromal depressive symptoms in postmenopausal women and may enhance antidepressant response for older women with major depression.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Effects of muscle glycogen depletion on some metabolic and physiological responses to submaximal treadmill exercise.

The aim of this study was to investigate the effects of reduced muscle glycogen concentration on some physiological and metabolic responses during moderate intensity treadmill exercise in horses. Six Thoroughbred geldings were randomly allocated to 2 treatments (protocols A and B) or control in a 3 x 3 replicated Latin square design. In protocol A, horses performed low intensity exercise while horses in protocol B performed short bursts of high intensity exercise. Protocol A was designed to induce glycogen depletion mainly of slow twitch muscle fibers while protocol B aimed to deplete mainly fast twitch muscle fibers. Horses in the control group did not undergo exercise prior to the exercise test. Five hours after glycogen depletion, horses performed treadmill exercise at 60% VO2max at a treadmill slope of 10% until fatigue (20-30 min). The induced glycogen depletion prior to exercise had no significant effect on plasma glucose, insulin, or lactate concentrations during the exercise test, and there was no effect on glycogen utilization rate, although respiratory exchange ratios were lower in the glycogen-depleted groups. The VO2, heart rate and central blood temperature did not vary significantly between the protocols A and B and control throughout the exercise test. It was concluded that 20-30% depletion of glycogen concentration in the middle gluteal muscle resulted in a shift towards fat metabolism, but does not significantly affect heart rate, oxygen uptake, or concentrations of plasma glucose and lactate during moderate intensity exercise.

Animals↗
PubMed1998

Nonspecific cytotoxic cell receptor protein-1: a novel (predicted) type III membrane receptor on the teleost equivalent of natural killer cells recognizes conventional antigen.

The phylogenetic model for "conventional" antigen recognition by NK cells may be a protein (NCCRP-1) recently identified from catfish nonspecific cytotoxic cells (NCC). NCCRP-1 may be a Type III membrane protein. The antigen binding domain was identified by competition experiments using synthetic peptides. Within this domain, a 38-mer peptide (aa 104-140) inhibited NCC killing of IM-9, HL-60, NC-37, U937, and MOLT-4 target cells. Biotinylated 38-mer also bound to IM-9 target cells. A mab which inhibited conjugate formation between NCC and target cells also bound to the 38-mer. Nonbiotinylated 38-mer inhibited mab 5C6 binding to immobilized homologous biotinylated peptide in cold competition ELISA experiments. Peptide 104-140 was truncated into two peptides. Amino acid 104-119 bound to (68%) and inhibited lyis of IM-9 target cells, whereas aa 120-140 had no activity. A predicted structure-function algorithm suggested an N-terminal domain containing BOX-1 motifs for cytokine activation; a C-terminal domain containing abundant phosphorylation sites (i.e., Y, S, and T amino acids); and an extracellular antigen binding domain.

Algorithms↗
PubMed1998

In vivo modulation of innate resistance to Edwardsiella ictaluri with a phosphatase inhibitor.

Catfish were treated with the protein phosphatase inhibitor sodium orthovanadate (vanadate) and challenged with the pathogen Edwardsiella ictaluri to investigate the relationship between the in vivo immunoregulatory effects of tyrosine and serine phosphatases on nonspecific modulation of resistance to bacterial infections. Two different infection protocols were used: fish were pretreated by immersion in vanadate and subsequently infected (by immersion) with 1 LD100 E. ictaluri, or fish were injected (intraperitoneally, i.p.) with bacteria and simultaneously treated (by immersion) with 25 microM vanadate. In the absence of vanadate, both infection models produced fulminant infection by 10 or 6 d, respectively. Zero to 48 h treatment with vanadate (by immersion) prior to infection produced 17 to 100% survival of infected fish. In addition to augmentation of inmate immunity, vanadate enhanced acquired immunity to this pathogen. Fish which had vanadate-induced resistance to primary infection were 'immune' to secondary challenge with a LD100 of E. ictaluri. Experiments were done to determine the mechanism(s) of the altered innate resistance. Catfish were injected (i.p.) with E. ictaluri and simultaneously treated (by immersion) with 25 microM vanadate. Assays were done to measure nonspecific cytotoxic cell (NCC) activity at 0, 24, 48, 72 and 96 h post-infection/vanadate treatment. Increased NCC activity at 48 to 96 h post-infection appeared to correlate with resistance to bacterial related mortality. These data indicated that in vivo vanadate treatment of catfish significantly increased resistance to otherwise fulminant E. ictaluri infections. This effect coincided with the initiation of resistance to secondary infections without additional vanadate treatments. Vanadate-modulated resistance in catfish may be associated with augmented NCC activity.

Animals↗
PubMed1998

Increased camptothecin toxicity induced in mammalian cells expressing Saccharomyces cerevisiae DNA topoisomerase I.

The yeast Saccharomyces cerevisiae has been useful in establishing the phenotypic effects of specific mutations on the enzymatic activity and camptothecin sensitivity of yeast and human DNA topoisomerase I. To determine whether these phenotypes were faithfully reiterated in higher eukaryotic cells, wild-type and mutant yeast Top1 proteins were epitope-tagged at the amino terminus and transiently overexpressed in mammalian COS cells. Camptothecin preferentially induced apoptosis in cells expressing wild-type eScTop1p yet did not appreciably increase the cytotoxic response of cells expressing a catalytically inactive (eSctop1Y727F) or a catalytically active, camptothecin-resistant eSctop1vac mutant. Using an epitope-specific antibody, immobilized precipitates of eScTop1p were active in DNA relaxation assays, whereas immunoprecipitates of eScTop1Y727Fp were not. Thus, the enzyme retained catalytic activity while tethered to a support. Interestingly, the mutant eSctop1T722A, which mimics camptothecin-induced cytotoxicity in yeast through stabilization of the covalent enzyme-DNA intermediate, induced apoptosis in COS cells in the absence of camptothecin. This correlated with increased DNA cleavage in immunoprecipitates of eScTop1T722Ap, in the absence of the drug. The observation that the phenotypic consequences of expressing wild-type and mutant yeast enzymes were reiterated in mammalian cells suggests that the mechanisms underlying cellular responses to DNA topoisomerase I-mediated DNA damage are conserved between yeast and mammalian cells.

Animals↗
PubMed1998

The relationship of depression to cardiovascular disease: epidemiology, biology, and treatment.

This article reviews the burgeoning literature on the relationship of mood disorders and heart disease. Major depression and depressive symptoms, although commonly encountered in medical populations, are frequently underdiagnosed and undertreated in patients with cardiovascular disease (CVD). This is of particular importance because several studies have shown depression and its associated symptoms to be a major risk factor for both the development of CVD and death after an index myocardial infarction. This review of the extant literature is derived from MEDLINE searches (1966-1997) using the search terms "major depression," "psychiatry," "cardiovascular disease," and "pathophysiology." Studies investigating pathophysiological alterations related to CVD in depressed patients are reviewed. The few studies on treatment of depression in patients with CVD are also described. Treatment of depression in patients with CVD improves their dysphoria and other signs and symptoms of depression, improves quality of life, and perhaps even increases longevity. Recommendations for future research are proposed.

Adult↗
PubMed1998

Skeletal muscle adaptations to prolonged training, overtraining and detraining in horses.

Thirteen standard-bred horses were trained intensively for 34 weeks and detrained for 6 weeks to study skeletal muscle adaptations to prolonged training, overtraining and detraining. Training included endurance (phase 1, 7 weeks), high-intensity (phase 2, 9 weeks) and overload training (OLT) (phase 3, 18 weeks). During phase 3, horses were divided into two groups, OLT and control (C), with OLT horses performing greater intensities and durations of exercise than C horses. Overtraining was evident in OLT horses after week 31 and was defined as a significant reduction in treadmill run time in response to a standardised exercise test (P<0.05). Relationships between peripheral (skeletal muscle) and whole body (maximum O2 uptake, V.O2, max, treadmill run time) adaptations to training were determined. Prolonged training resulted in significant adaptations in morphological characteristics of skeletal muscle but the adaptations were limited and largely completed by 16 weeks of training. Fibre area increased in all fibres while the number of capillaries per fibre increased and the diffusional index (area per capillary) decreased. Mitochondrial volume density continued to increase throughout 34 weeks of training and paralleled increases in V.O2,max and treadmill run time. Significant correlations were noted between mitochondrial volume and V.O2,max (R=0.71), run time and V.O2,max (R=0.83) and mitochondrial volume and run time (R=0.57). We conclude that many of adaptive responses of muscle fibre area and capillarity occur in the initial training period but that markers of oxidative capacity of muscle indicate progressive increases in aerobic capacity with increases in training load. The lack of differences between C and OLT groups indicated that there may be an upper limit to the ability of training stimulus to evoke skeletal muscle adaptive responses. There was no effect of overtraining or detraining on any of the adaptive responses measured.

Adaptation, Physiological↗
PubMed1998

Psychiatric morbidity in endocrine disorders.

Psychiatric disturbances are frequently observed during the course of endocrine disorders. This article discusses the history, current knowledge, assessment, and treatment of psychiatric morbidity in endocrine disorders. The primary focus is on biologic links between psychiatric symptoms and endocrine dysfunction. Psychiatric disorders associated with abnormalities of the pituitary, thyroid, parathyroids, adrenals, and gonads are discussed as well as the chronic illness of diabetes mellitus.

Endocrine System Diseases↗
PubMed1998

Receptor associated phosphorylation following monoclonal antibody or synthetic peptide binding to nonspecific cytotoxic cells.

We have previously shown that crosslinkage of a receptor protein on catfish nonspecific cytotoxic cells (NCC) with anti-receptor monoclonal antibody or with a synthetic peptide activates cytotoxicity and initiates signalling responses. Receptor linked signalling was associated with the production of increased levels of expression of 50-60 and 20-30 kDa phosphoproteins determined by immunoprecipitation with anti-phosphoserine and anti-phosphotyrosine mabs. These proteins are components of a macromolecular protein complex (>200 kDa) determined by reducing and nonreducing SDS-PAGE. The calcium ionophore A23187 treatment produced the same pattern of phosphoprotein expression as peptide or mab. Maximum phosphoserine expression occurred at 15'-30' post-mab binding. We now show that synthetic peptide or mab treatment initiated the same serine and tyrosine phosphorylation profiles. The PKC specific inhibitor MDL 29,152 produced 50% inhibition of NCC lysis of IM-9 target cells, and completely inhibited serine phosphorylation of peptide activated cells but had no effect on tyrosine phosphorylation of the phosphointermediates. Genistein pretreatment of NCC inhibited cytotoxicity and tyrosine phosphorylation. Sequential immunprecipitation of the phosphointermediate demonstrated that the phosphorylated serine and tyrosine residues were on the same 50-60 kDa protein. These data indicate that both proximal and distal signalling events required for NCC activation may be associated with ATPase phosphorylation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Special considerations: use of lithium in children, adolescents, and elderly populations.

Certain populations of patients require special considerations when lithium is prescribed. Children and adolescents have higher volumes of body water and more active renal glomerular filtration rates than adults. Their central nervous system is developing and therefore is vulnerable to the impact of substances, including medications such as lithium, that can cause side effects or adverse events. Elderly patients have less body water, slower metabolism, and often comorbid illnesses, so they also require close evaluation and monitoring when prescribed lithium. This paper examines the indications for, pharmacokinetics of, clinical uses of, and side effects of lithium in children, adolescents, and the elderly. Use of alternate mood stabilizers is also addressed briefly.

Abnormalities, Drug-Induced↗
PubMed1998

Depression and cardiac disease.

The relationship of mood disorders to cardiovascular disease is receiving considerable attention. The literature on diagnosing depression in patients with cardiovascular disease (CVD), is briefly summarized. There is overwhelming evidence that major depression and other mood disorders, though common, are underdiagnosed and undertreated in patients with coronary artery disease (CAD). This is of paramount importance because depression appears to be a major risk factor in both the development of CAD and in death after myocardial infarction. The pathophysiological alterations in depression that may underlie vulnerability to cardiovascular disease are reviewed with a focus on alterations in heart rate variability and platelet aggregation. The studies on treatment of depression in patients with CAD are also summarized. Treatment of depression in CAD patients appears to be effective, improves quality of life, and might increase longevity.

Depressive Disorder↗
PubMed1997

Molecular characterization of a protozoan parasite target antigen recognized by nonspecific cytotoxic cells.

The target cell antigen(s) on tumor cells and on protozoan parasites recognized by NK and nonspecific cytotoxic cells (NCC) has not yet been specifically identified. NCC may be the teleost equivalent of NK cells and IL-2-activated NK cells. A ligand recognized by NCC has been identified. It is expressed on both protozoan parasites and mammalian tumor target cells. In the present study, a protozoan parasite antigen (NK target antigen/NKTag/p46) was purified from Tetrahymena pyriformis and the entire amino acid sequence was deduced from cDNA. Soluble and purified NKTag inhibited NCC lysis of human and mouse transformed target cells. Homology comparisons using Swissprot database revealed that NKTag is a novel protein. Molecular weight computation of the deduced sequence demonstrated that NKTag is a 48.17-kDa protein containing 422 amino acids with relatively high percentages of tyrosine and serine residues. Expression of NKTag on various mammalian tumor target cells, normal tissue, and T. pyriformis was determined using anti-multiple antigenic peptide (MAP) monoclonal antibody (mab) 22A12 [generated against an N-terminal 20-mer (aa 61-80) of p46]. This mab bound to tissue-cultured and tumor cells (YAC-1, IM-9, NC-37, MOLT-4, and U937) with low levels of binding to fish, mouse, and equine cells. Studies were also done to determine if purified and iodinated NKTag bound specifically to NCC. Binding was saturable and specific. These data provide evidence that NCC recognize a target cell ligand which is found on both protozoan and tumor cells. This may provide an explanation as to how NCC (including activated NK cells) recognize a vast array of targets in the absence of haplotype recognition and in spite of a diverse species of origin.

Amino Acid Sequence↗
PubMed1997

Severe stress, depressive symptoms, and changes in lymphocyte subsets in human immunodeficiency virus-infected men. A 2-year follow-up study.

BACKGROUND: This study examined how severe stress and depressive symptoms were related to changes in immune measures during a 2-year period in a sample of gay men with human immunodeficiency virus (HIV) infection. These analyses follow up our initial cross-sectional observations that severe stress was correlated with lower levels of natural killer (NK) cells and CD8+ T lymphocytes in these men. METHODS: Data were collected in North Carolina as part of an ongoing, longitudinal study, the Coping in Health and Illness Project. Sixty-six HIV-infected gay men, who were asymptomatic at baseline, were assessed systematically at 6-month intervals. RESULTS: Severe stress and depressive symptoms were independently related to decreases on immune measures from entry to 2-year follow-up, that is, declines in CD8+ T cells and CD56+ and CD16+ NK cell subsets. Subjects most likely to have decreases on these immune measures were those who scored above the median on both stress and depressive symptoms. CONCLUSIONS: Our findings are among the first prospective data showing that stress and depressive symptoms, especially when they occur jointly, are associated with decreased number of NK and CD8+ T lymphocytes in HIV-infected men. Since these immune cells may play a protective role in the progression of HIV infection, our data suggest that stress and depressive symptoms may have clinical implications for the course of this disease.

Adult↗
PubMed1997

Collagen VII expression in human chronic wounds and scars.

Collagen VII is the major structural component of the anchoring fibrils that stabilize the cutaneous basement membrane on the dermis. Disruption and, more usually, destruction of the basement membrane are characteristic of wounds that are slow, or fail, to heal, such as chronic lower-limb or pressure ulcers. In this study, the expression of collagen VII was analysed in 28 human chronic cutaneous wounds or scars using a reverse transcription-polymerase chain reaction (RT-PCR) technique. Collagen VII expression was detected in 26 of these 28 cutaneous wounds, but not in two wounds, neither of which showed any clinical evidence of healing.

Adult↗
PubMed1997

Explaining "pain and suffering" awards: the role of injury characteristics and fault attributions.

The present research explored factors thought to affect compensatory awards for non-economic harm ("pain and suffering") in personal injury cases. Experiment 1 showed that the nature and severity of the plaintiff's injury had a strong effect on perceptions of the extent of harm suffered and on award amounts. The parties' relatively active or passive roles in causing the injury affected assessments of their degree of fault, but perceived fault had little influence on awards. Experiment 2 replicated with more varied cases the strong impact of injury severity on harm perception and on awards for pain and suffering. In both studies, the disability and the mental suffering associated with injuries were stronger predictors of awards than were pain and disfigurement.

Accidents↗