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Biomedical subjects

A Brooks

Publications and source records attributed to A Brooks.

At least 73 records · Page 4Linked to original sources
PubMed1997

Patients' perceptions of the pre-operative information they need about events they may experience in the intensive care unit.

Through a descriptive survey, this study examined the pre-operative information which patients need about the events they may experience in intensive care, when they are admitted there following elective surgery. A subsidiary aim was to find out how they felt this information should be delivered. Questionnaires were posted to a convenience sample of 57 people who had been admitted post-operatively to one ICU in the past year. Forty-three (75%) of the questionnaires were returned and were analysed with the five returned in the pilot study. The results suggested that pre-operative information about ICU was perceived helpful by all respondents, particularly the management of pain and nausea, the likely site of pain, mouth care, the high nurse:patient ratio and having a urinary catheter. Information rated helpful less frequently, included noise levels, visiting times and men and women being nursed in the same room. The most popular method for receiving the information was via a pre-operative visit from a nurse working in ICU. In view of the sampling procedure and the validity of data collection methods, these findings cannot be generalized.

Adaptation, Psychological↗
PubMed1997

Histamine H2 receptor antagonist-refractory oesophagitis: the efficacy of long-term omeprazole maintenance treatment.

BACKGROUND: Erosive oesophagitis refractory to high dose histamine H2 receptor antagonists (definition: failure to heal fully after > or = 3 months' treatment with cimetidine 3.2 g or ranitidine 0.9 g) responds well to omeprazole 40 mg daily but frequently relapses when the patients are put back on maintenance H2 receptor antagonists at medium or even high dose (e.g. cimetidine 1.6 g and 3.2 g, respectively). AIM: To investigate the efficacy of maintenance omeprazole 20 mg daily in refractory erosive oesophagitis. PATIENTS & METHODS: In this open, sequential study, patients with H2 receptor antagonist-refractory oesophagitis were healed on omeprazole 40 mg daily and then put on maintenance H2 receptor antagonists (cimetidine 1.6 g or 3.2 g). Relapses were re-treated with omeprazole 40 mg; upon rehealing, patients were put on maintenance omeprazole 20 mg daily for up to 4.5 years. RESULTS: Healing on omeprazole occurred in 38 out of 39 patients (97%) at 12 weeks. Only six of the 38 patients (16%) relapsed (asymptomatic in half) during subsequent maintenance treatment, whereas all had relapsed earlier on high dose H2 receptor antagonists. CONCLUSION: Within the limits of interpretation of an open study, omeprazole 20 mg daily seems effective in maintaining prolonged remission in this group of patients with H2 receptor antagonist-refractory oesophagitis.

Adult↗
PubMed1996

Regulation of inducible nitric oxide synthase expression in IFN-gamma-treated murine macrophages cultured under hypoxic conditions.

We recently reported that a hypoxia-responsive element mediates a novel pathway of transcriptional activation of the inducible nitric oxide synthase (iNOS) promoter in murine macrophages treated with IFN-gamma plus hypoxia (1% O2). In this study, we investigated the expression of NOS activity and the regulation of NOS induction in IFN-gamma treated ANA-1 murine macrophages or thioglycollate-elicited peritoneal macrophages cultured under hypoxic conditions. We found that murine macrophages stimulated with IFN-gamma plus hypoxia, despite a significant accumulation of iNOS mRNA, did not release nitrite into culture supernatant. However, cytosol from macrophages treated with IFN-gamma plus hypoxia contained significant levels of iNOS protein and enzymatic activity. Experiments in which cells were treated with IFN-gamma plus hypoxia and then cultured in normoxic conditions (20% O2) demonstrated that reoxygenation was required to achieve detectable accumulation of nitrite in the culture supernatant. Furthermore, we demonstrated that IL-4 inhibited IFN-gamma plus hypoxia-dependent induction of iNOS mRNA expression, iNOS protein, and enzymatic activity. Experiments in which ANA-1 macrophages were transfected transiently with the full-length iNOS promoter linked to a chloramphenicol acetyltransferase reporter gene demonstrated that IL-4 also down-regulated the IFN-gamma plus hypoxia-induced activation of the iNOS promoter. These data establish that hypoxia is a costimulus with IFN-gamma for the induction of iNOS activity in ANA-1 macrophages as well as in murine peritoneal macrophages, and they provide the first evidence that IL-4 inhibits hypoxia-inducible gene expression. In addition, our results suggest that hypoxia, which occurs in many pathologic conditions, may play an important role in the activation of murine macrophages.

Animals↗
PubMed1996

Effect of radon on the immune system: alterations in the cellularity and functions of T cells in lymphoid organs of mouse.

Exposure to radon and its progeny induces significant damage to the cells of the respiratory tract and causes lung cancer. Whether a similar exposure to radon would alter the functions of the immune system has not been previously investigated. In the current study, we investigated the effect of exposure of C57BL/6 mice to 1000 or 2500 working-level months (WLM) of radon and its progeny by inhalation, on the number and function of T lymphocytes in lymphoid organs. The control mice received uranium ore dust carrier aerosol by inhalation. Exposure to radon induced marked decrease in the total cellularity of most lymphoid organs such as thymus, peripheral lymph nodes (PLN), and lung-associated lymph nodes (LALN), when compared to the controls. The percentage of T cells increased, while that of non-T cells decreased, in all peripheral lymphoid organs at both the doses of radon. In the thymus, particularly at 2500 WLM of radon exposure, there was a marked decrease in CD4+CD8+ T cells and an increase in the immature CD4-CD8- T cells. Such alterations in both the numbers and percentages of lymphocytes and macrophages in radon-exposed mice may have resulted from the cell killing by the alpha particles as the immune cells were migrating through the lungs, or it may have been caused by altered migration of cells, inasmuch as expression of CD44, a molecule involved in migration and homing of immune cells, was significantly altered on cells found in different lymphoid organs. In the LALN, where one would predict the largest number of damaged cells to be present, there was a significant decrease in the T-cell responsiveness to mitogens while the B-cell response was not affected. Such alterations may have resulted from the direct effect of alpha-particle exposure on the migrating lymphocytes, altered percentage of lymphocytes as seen in secondary lymphoid organs, or altered expression of adhesion molecules involved in cell activation such as CD44 and CD3. Interestingly, radon exposure caused and increase in the T- and B-cell responsiveness to mitogens in the spleen and PLN. Since there is little evidence of direct radiation dose from radon in lymphoid organs, our studies demonstrating immunological alterations suggest an indirect effect of radon exposure that may have significant repercussions on the development of hypersensitivity and increased susceptibility to infections and cancer in the lung.

Administration, Inhalation↗
PubMed1996

Mapping quantitative trait loci affecting life history traits in the nematode Caenorhabditis elegans.

We have identified chromosomal regions containing quantitative trait loci (QTLs) specifying life history traits in recombinant-inbred strains of the nematode Caenorhabditis elegans. This approach also allows us to examine epistatic interactions between loci and pleiotropic effects on different traits at specific loci. QTLs for mean life span were identified on chromosomes II (near stP101), IV (stP5) and the X (stP61), and QTLs for fertility were identified on II (maPI), III (stP19) and IV (stP51). The QTLs for mean life span accounted for 90% of the genetic component of variance. The loci for mean fertility accounted for 88% of the genetic component of variance. Additional QTLs for temperature-sensitive fertility [II (stP36) and V (stP6)] and internal hatching [IV (stP5)] were also mapped in these crosses. We found evidence for epistatic effects on mean life span between maP1 and bP1 (V), and for epistatic effects on mean fertility between stP36 and stP6, between stP98 (II) and stP192 (V), between maP1 and stP127 (III), between maP1 and stP103 (X), and between stP5 and stP6. Negatively correlated, pleiotropic effects on mean life span and internal hatching were found linked to stP5.

Animals↗
PubMed1995

Treatment of Vietnam War veterans with PTSD: a comparison of eye movement desensitization and reprocessing, biofeedback, and relaxation training.

Analyses of scaled self-report data from Vietnam War veterans receiving inpatient treatment for Post-Traumatic Stress Disorder drawn during a program evaluation study suggested inpatient treatment as provided by the program resulted in significant improvement in the areas of Anxiety, Anger, Depression, Isolation, Intrusive Thoughts (of combat experiences), Flashbacks, Nightmares (of combat experiences), and Relationship Problems. Comparing the relative effects of the incremental addition of Eye Movement Desensitization and Reprocessing (EMDR), Relaxation Training, and Biofeedback found that EMDR was for most problems the most effective extra treatment, greatly increasing the positive impact of the treatment program.

Analysis of Variance↗
PubMed1995

Peptide binding to MHC class I molecules: implications for antigenic peptide prediction.

The human mayor histocompatibility complex class I molecule HLA-A2 preferentially binds peptides that contain Leu at P2 and Val or Leu at the C terminus. The other amino acids in the peptide also contribute to binding positively or negatively. It is possible to estimate the binding stability of HLA-A2 complexes containing particular peptides by applying coefficients, deduced from a large amount of binding data, that quantify the relative contribution of each amino acid at each position. In this review, we describe the molecular basis for these coefficients and demonstrate that estimates of binding stability based on the coefficients are generally concordant with experimental measurements of binding affinities. Peptides that contained cysteine were predicted less well, possibly because of complications resulting from peptide dimerization and oxidation. Apparently, peptide binding affinity is largely controlled by the rate of dissociation of the HLA/peptide/beta 2-microglobulin complex, whereas the rate of formation of the complex has less impact on peptide affinity. Although peptides that bind tightly to HLA-A2, including many antigenic peptides bind much more weakly. Therefore, a full understanding of why certain peptides are immunodominant will require further research.

Amino Acid Sequence↗
PubMed1995

Antigen processing and presentation by a murine myoblast cell line.

The ability of non-professional antigen-presenting cells (APC) to process and present antigen to the immune system has been the subject of debate in autoimmunity and tumour immunology. The role of muscle cells in the processing and presentation of antigen to T cells via class I and class II MHC pathways is of increasing interest. Muscle cells are the targets of autoimmune attack in the inflammatory muscle diseases, and direct intramuscular injection of antigen-expressing DNA constructs is under scrutiny as a means of vaccination. Furthermore, the immunological properties of muscle cells are of relevance in attempts to transfer myoblasts as replacement cells in dystrophic diseases or as depot cells for the secretion of certain molecules in deficiency states. Using class I and class II MHC transfectant clones of the C2C12 myoblast cell line, myoblasts have been shown to be capable of presenting antigen to, and stimulating secretion of IL-2 by, T cell hybridomas via both of these pathways. The epitopes which are dominantly presented by professional APC after processing of native antigens were also presented by the myoblast cell line after processing of either ovalbumin (class I) or hen egg lysozyme (class II). Further, antigen processing and presentation via the class II pathway were enhanced by pretreatment of the myoblasts with interferon-gamma (IFN-gamma). Up-regulation of invariant chain expression by this treatment may have contributed to this enhanced presentation, but an effect of IFN-gamma on the expression of other molecules such as H-2 DM may have also played a role. The demonstration of the antigen-presenting properties of these myoblasts is of relevance to all three areas mentioned above. In each situation myoblasts comprise a significant population within muscle. In the case of inflammatory muscle diseases the process of muscle degeneration and regeneration is on-going, while in the vaccination procedure some muscle damage occurs, and vaccination is more effective when muscle damage has preceded inoculation.

Animals↗
PubMed1995

Fractures of the coracoid process.

We have reviewed 12 fractures of the coracoid process. In two of these patients the fracture extended into the body of the scapula and resulted in displacement of the glenoid. In some cases, there were associated acromioclavicular and glenohumeral dislocations or fractures of the clavicle and the acromion. Two patients required internal fixation to restore congruence of the glenoid; the others were treated conservatively with success. We present a new classification of coracoid fractures which helps in their management.

Adult↗
PubMed1994

Interleukin-4 inhibits indoleamine 2,3-dioxygenase expression in human monocytes.

Indoleamine 2,3-dioxygenase (IDO), a flavin-dependent enzyme that catalyzes the conversion of tryptophan to kynurenine, is induced in peripheral blood mononuclear cells by interferon-gamma (IFN gamma). Interleukin-4 (IL-4) is a cytokine that modulates the functional properties of monocytes/macrophages, and we investigated the effects of IL-4 on IDO. We showed that IL-4 inhibited the induction of IDO mRNA and IDO activity by IFN gamma in human monocytes. The inhibitory effect was evident with as little as 2 U/mL of IL-4. These results provide the first evidence that a cytokine can provide a negative signal for IDO expression and that IL-4 can influence the catabolism of tryptophan.

Base Sequence↗
PubMed1994

Mortality rates in a genetically heterogeneous population of Caenorhabditis elegans.

Age-specific mortality rates in isogenic populations of the nematode Caenorhabditis elegans increase exponentially throughout life. In genetically heterogeneous populations, age-specific mortality increases exponentially until about 17 days and then remains constant until the last death occurs at about 60 days. This period of constant age-specific mortality results from genetic heterogeneity. Subpopulations differ in mean life-span, but they all exhibit near exponential, albeit different, rates of increase in age-specific mortality. Thus, much of the observed heterogeneity in mortality rates later in life could result from genetic heterogeneity and not from an inherent effect of aging.

Aging↗
PubMed1994

Experience with lower urinary tract disruptions associated with pelvic fractures: implications for emergency room management.

A retrospective review of prospectively gathered data from 249 trauma patients was undertaken to study the association of lower urinary tract disruptions with pelvic fractures and to confirm guidelines for the initial investigation and management of such patients in the emergency room. Of 249 patients with pelvic fractures, 124 (50%) had haematuria and 17 (7%) had lower urinary tract disruptions (7 urethral ruptures, 9 bladder ruptures and 1 patient with both bladder and urethral ruptures). Gross haematuria or blood at the urethral meatus was noted in 16 of 17 patients with urological injuries. Twenty-five per cent of patients with unstable pelvic fractures had lower urinary tract disruption compared to 6% of patients with stable fractures (P < 0.05). Retrograde urethrography followed by cystography is indicated in all cases of pelvic fractures with blood at the urethral meatus, macroscopic haematuria or associated signs such as inability to void and perineal haematoma. Urinary diversion alone was used in partial urethral ruptures while surgical exploration and repair were performed in complete urethral ruptures and in most cases of bladder ruptures.

Adolescent↗
PubMed1993

Effects of IL-4 depletion on the antibody response to Pseudomonas aeruginosa lipopolysaccharide in mice.

These studies were done to examine the role of interleukin-4 (IL-4) in the generation of isotype specific antibody responses of mice to Pseudomonas aeruginosa lipopolysaccharide (PALPS) by neutralization of IL-4 in vivo using anti-IL-4 antibody (11B11). We found that the administration of anti-IL-4 antibody (11B11) 24 h before immunization with PALPS resulted in a decreased PALPS-specific antibody response for all isotypes examined (IgM, IgG1, IgG2a, IgG2b, IgG3). By contrast, we observed that the non-antigen-specific (polyclonal) IgM response of mice following treatment with 11B11 antibody and PALPS was increased while the polyclonal responses for the other isotypes were unaffected. When mice were given recombinant IL-10 at the time of immunization with PALPS there was a decrease in the PALPS-specific antibody response but an increase in the polyclonal IgM, IgG2a, IgG2b, IgG3 response whereas the polyclonal IgG1 response was decreased by a five-fold margin. The results of these studies suggest that both the antigen-specific and the polyclonal response can be influenced in a different manner by IL-4 or by IL-10.

Animals↗
PubMed1993

Serum placental protein 14 concentrations in the first trimester of ovum donation pregnancies.

The concentration of the endometrial glycoprotein placental protein 14 (PP14) has been measured at weekly intervals during the first trimester in serum obtained from women who had become pregnant naturally (n = 15, all singleton) or following ovum donation (n = 16, 15 singleton and one twin) after ovarian failure (n = 13), Turner's syndrome (n = 2) or post-chemotherapy (n = 1). The concentration of PP14 failed to rise in ovum donation pregnancies, and was significantly reduced compared to the concentration in natural conceptions from 5 to 13 weeks gestation (P < 0.05-0.01). These findings demonstrate that the corpus luteum is essential for the normal increase in serum PP14 in the first trimester. Furthermore, they suggest that progesterone is not the major stimulus to PP14 synthesis in early pregnancy.

Female↗