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Biomedical subjects

D Armstrong

Publications and source records attributed to D Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed2003

Pseudomonas cross-infection from cystic fibrosis patients to non-cystic fibrosis patients: implications for inpatient care of respiratory patients.

A 14-year-old boy with bronchiectasis secondary to chronic aspiration developed multiresistant Pseudomonas aeruginosa lower respiratory disease following several inpatient periods where accommodation and physiotherapy services were shared with cystic fibrosis (CF) patients known to be infected with the genetically identical strain of P. aeruginosa. Cross-infection with P. aeruginosa between CF patients and non-CF patients has not previously been described, and this finding raises significant issues relevant to the treatment of patients with non-CF suppurative lung disease.

Adolescent↗
PubMed2003

Adrenal suppression from high-dose inhaled fluticasone propionate in children with asthma.

This cross-sectional study was designed to examine the prevalence of adrenocortical suppression in children with asthma treated with high-dose inhaled fluticasone propionate (FP). Children and adolescents (n=50) with asthma, treated with inhaled FP at a dose of > or = 1,000 mg a day for > or = 6 months, were enrolled. Early morning serum cortisol was performed. Subjects with a serum cortisol of < 400 nmol x L(-1) had a tetracosactrin stimulation test. Fifty subjects of mean age 13.1 yrs were treated with a mean dose of 924.7 microg x m(-2) x day(-1) FP for a mean duration of 2 yrs. Of the 50 subjects, 36 (72%) had serum cortisol levels of < 400 nmol x L(-1) and underwent tetracosactrin stimulation test. Of these, 6 (17%) demonstrated a less than two-fold increase in serum cortisol from baseline and peak cortisol level of < or = 550 nmol x L(-1) at 30 or 60 min poststimulation. There was a significant negative correlation between the dose of FP x m(-2) and stimulated peak cortisol level. Biochemical evidence of adrenocortical insufficiency was demonstrated in 12% of the subjects, indicating that high-dose fluticasone propionate use may be associated with dose-dependent adrenocortical suppression.

Administration, Inhalation↗
PubMed2002

New mental retardation syndrome associated with ocular colobomas, cleft palate, and genital, skeletal, and craniofacial abnormalities.

We describe three Canadian brothers of Cree origin, with a previously undescribed pattern of malformation including distinctive craniofacial abnormalities with triangular facies, hypertelorism, low-set and posteriorly rotated ears, ocular colobomas, ptosis, brachycephaly with widely separated sutures, cleft soft palate, undescended testes, bifid scrotum and hypospadius, wide webbed neck, webbed fingers, pectus excavatum and hypersegmented sternum, and severe psychomotor retardation. The presence of normal brain imaging and physical growth distinguishes them from other syndromes with overlapping abnormalities. This is either an X-linked or autosomal recessive condition.

Abnormalities, Multiple↗
PubMed2002

Listeriosis in recipients of allogeneic blood and marrow transplantation: thirteen year review of disease characteristics, treatment outcomes and a new association with human cytomegalovirus infection.

Listeriosis is uncommon in recipients of allogeneic blood, marrow and organ transplantation. Six patients with systemic Listeria monocytogenes infection during 1985-1997 at Bone Marrow Transplantation Service, Memorial Sloan-Kettering Cancer Center are described. In two male and four female patients, the median duration from transplantation to isolation of L. monocytogenes was 62.5 (range 29 to 821) days. Among five allogeneic marrow transplant recipients, four (80%) received HLA antigen matched, T cell-depleted grafts from three unrelated and a single related donor. One patient underwent mismatched-related marrow graft transplant. Cord stem cell transplantation was performed in a single patient. Two required therapy for graft-versus-host disease (GVHD). The 13 year incidence of systemic Listeria infections was 0.47 percent. All six presented with fever (>39 degrees C), and L. monocytogenes bloodstream invasion. Mental status changes and meningioencephalitis were observed in two (33.3%). A concurrent primary opportunistic infection was present in five individuals (83.3%), and four (80%) were being treated for acute human cytomegalovirus (HCMV) viremia. Sixty-six percent responded to therapy and two died from unrelated, non-listeric causes. Systemic listeriosis was uncommon in our high-risk allogeneic blood and marrow transplantation population, and response to therapy with parenteral ampicillin and gentamicin was excellent. The association between primary HCMV reactivation and subsequent listeric infection emphasizes the significance of HCMV-related dysfunction in hosts' cellular immune responses, especially in the setting of allogeneic transplantation.

Adolescent↗
PubMed2002

Prospective evaluation of Candida species colonization in hospitalized cancer patients: impact on short-term survival in recipients of marrow transplantation and patients with hematological malignancies.

Most hematogenous candidiasis originates from endogenous host flora. The impact of clinically prominent Candida colonization on short-term mortality ( 50 colonies of Candida from non-sterile sites. Fourteen (7.1%) patients were granulocytopenic (ANC <or=100/microl). Nineteen (9.8%) had undergone marrow transplantation, 26 (13.5%) had a hematologic malignancy and 129 (66.5) had non-hematologic cancer. Candida isolates (216) were collected form 210 specimens. Fifty-three (27.5%) patients died; 25 (19.4%) with solid tumors, compared to 16 (61.5%) with hematological malignancy, and 11 (57.9%) BMT recipients (P < 0.001). No deaths were seen in patients with AIDS, and one (7.7%) in a patient with a benign condition (P < 0.001). Twenty-six (29.2%) patients with respiratory tract, 13 (23.2%) with gastrointestinal tract, and three (14.3%) with genitourinary tract colonization died. In patients with multiple-site colonization, mortality was significantly higher (45.5%) (P < 0.05). Mortality was higher in patients with C. glabrata (52.9%) and C. krusei (75%) colonization than with C. albicans (24.1%) (P < 0.025). This study shows that patients with hematologic cancer and recipients of marrow transplant with Candida colonization of multiple body sites, and colonization with C. glabata or C. krusei have poor survival.

AIDS-Related Opportunistic Infections↗
PubMed2002

The effects on GP prescribing of joining a commissioning group.

BACKGROUND: It is not known to what extent general practitioners (GP) can change their prescribing upon joining a commissioning group and what features of a commissioning group may promote prescribing change. The opportunity to study potential prescribing change arose with the formation of a limited number of Primary Care Commissioning Groups (PCCGs), a precursor of Primary Care Groups (PCGs) and Primary Care Trusts (PCTs). METHODS: This was a controlled study of general practice prescribing costs. All practices (n=24) within one inner city PCCG were compared with matched controls that were not part of a PCCG. Cross sectional survey data was collected from the PCCG practices to determine possible reasons for prescribing change. RESULTS: The total annual prescribing cost rose by 4.0% in the PCCG practices and by 6.9% in controls (P=0.01). Significant cost containment was found for gastrointestinal prescribing (P=0.03), attributable to differences in the cost of proton pump inhibitors (PPIs) which fell by 0.7% in the PCCG but rose by 7.3% in controls (P=0.03). Total relative savings in the PCCG practices amounted to around pound 220,000. General practitioners making the greater savings in PPI costs within the PCCG, were more likely to report being influenced by information from the prescribing adviser. CONCLUSION: General practice prescribing costs were contained to a greater degree in practices participating in the PCCG. The differences in gastrointestinal prescribing were most marked for PPIs which were specifically targeted by the prescribing adviser. The GPs themselves attributed their own prescribing change to information provided by the prescribing adviser. Other factors operating within the PCCG may also have influenced prescribing such as a more locally based management system, different financial incentives and a greater degree of co-operative working amongst GPs.

Contract Services↗
PubMed2002

Staphylococcus aureus endocarditis in preterm neonates.

This article describes three extremely low birth weight infants with Staphylococcus aureus septicemia associated with insertion of a percutaneous central venous catheter who later developed endocarditis. Echocardiography demonstrated large vegetations although only one infant had a murmur. Following a 6-week course of intravenous flucloxacillin and netilmicin, the endocarditis completely resolved and further intervention was unnecessary, although one baby died later as a result of volvulus and chronic lung disease. Echocardiography should be performed to exclude invasive infection in infants with S. aureus septicemia even when there is no murmur or other evidence of endocarditis. If endocarditis is identified, a good outcome is possible with appropriate aggressive antibiotic therapy.

Anti-Bacterial Agents↗
PubMed2002

Effect of omeprazole on regional and temporal variations in intragastric acidity.

BACKGROUND: Conventional techniques for measuring gastric acidity have demonstrated the decrease in gastric acidity produced by proton pump inhibitors (PPI); however, such techniques do not detect transient or localized pH changes which may modify the intragastric environment without affecting the therapeutic efficacy of PPIs. AIM: To investigate local and temporal variations in intragastric pH and to test the hypothesis that omeprazole produces prolonged, generalized gastric anacidity (pH >6). METHODS: A single-blind study was conducted with triple-point 24-hour gastric pH-metry on days 7, 14 and 21 in 14 healthy, Helicobacter pylori-negative volunteers (7 M; 20-46 years) who received placebo for 7 days, followed by omeprazole 20 mg daily for 14 days. RESULTS: Omeprazole increased the median 24-hour pH significantly in the distal corpus (placebo: 1.3 (95% CI 1.1 to 1.6); omeprazole week 1: 4.0 (2.6-5.0); omeprazole week 2: 4.0 (2.8-4.6)) and at all other gastric recording sites (p < 0.01). At both corpus sites, nocturnal pH was lower and mealtime pH was higher than the non-meal daytime pH during placebo and both omeprazole administration periods; in the antrum, however, the major difference noted was that meal-time pH was higher than non-meal daytime pH. Antral pH was lower during meals and higher at night than proximal corpus pH. During placebo, gastric pH >6.0 was observed at 1 site only for 1.7% (median; 95% CI 0.4-3.3%), at 2 sites simultaneously for 0.24% (0.0-1.0%) and at 3 sites for 0.0% (0.0-0.28%), respectively, of the recording periods; during the second week of omeprazole, the equivalent results were 7.7% (1.4-14.0%), 4.9% (0.21-15.7%) and 4.7% (0.0-9.9%), respectively. CONCLUSIONS: Omeprazole, 20 mg daily, does not produce gastric anacidity despite significant increases in median 24-hour pH values. The time-, meal- and site-related variations in gastric pH observed under normal physiological conditions are seen to persist, with prolonged periods of low pH throughout the stomach and preservation of the normal, meal-related rise and nocturnal fall in gastric pH during omeprazole administration.

Circadian Rhythm↗
PubMed2002

Minimal and best linear combination of oxidative stress and antioxidant biomarkers to discriminate cardiovascular disease.

BACKGROUND AND AIM: Free radicals have been implicated in the atherosclerotic process of coronary heart disease (CHD). Well-developed laboratory methods may make available a large number of biomarkers of individual oxidative stress and antioxidant status. Such markers are able to quantify different phases of the oxidative stress and antioxidant status of an individual. However, limited knowledge is available on how to combine these biomarkers to best discriminate between individuals with and without CHD. METHODS AND RESULTS: We evaluated combined discrimination properties of six biomarkers of oxidative stress and antioxidant status, as indicators of CHD, in a cross-sectional random sample of 968 white men and women from Buffalo, New York. Individuals with CHD had significantly higher levels of thiobarbuturic acid reacting substances (TBARS) and uric acid, and significantly lower levels of high-density lipoproteins (HDL) after adjusting for age and gender, when compared to healthy subjects. There were no significant differences in erythrocyte glutathione (GSH), trolox equivalent antioxidant capacity (TEAC), and glutathione peroxidase (GSHPx) levels. TBARS were found to be the best discriminating of the biomarkers when it was individually evaluated. TBARS discriminate 76.2% (95% C.I. 0.66-0.82) of the CHD cases from healthy controls. When combining TBARS, GSH, TEAC, HDL, uric acid and GSHPx, they discriminate 81.5% (95% C.I.: 0.67-0.90) of the area under the curve. CONCLUSIONS: These preliminary findings suggest that the combination of multiple markers of oxidative stress does not greatly improve ability to differentiate between individuals with and without CHD compared to the use of TBARS alone.

Adult↗
PubMed2001

Immotile sperm and infertility in mice lacking mitochondrial voltage-dependent anion channel type 3.

Voltage-dependent anion channels (VDACs), also known as mitochondrial porins, are small channel proteins involved in the translocation of metabolites across the mitochondrial outer membrane. A single channel-forming protein is found in yeast, whereas higher eukaryotes express multiple VDACs, with humans and mice each harboring three distinct channels (VDAC1-3) encoded by separate genes. To begin to assess the functions of each of the three isoforms, the VDAC3 gene was inactivated by targeted disruption in embryonic stem cells. Here we show that mice lacking VDAC3 are healthy, but males are infertile. Although there are normal sperm numbers, the sperm exhibit markedly reduced motility. Structural defects were found in two-thirds of epididymal axonemes, with the most common abnormality being loss of a single microtubule doublet at a conserved position within the axoneme. In testicular sperm, the defect was only rarely observed, suggesting that instability of a normally formed axoneme occurs with sperm maturation. In contrast, tracheal epithelial cilia showed no structural abnormalities. In addition, skeletal muscle mitochondria were abnormally shaped, and activities of the respiratory chain complexes were reduced. These results demonstrate that axonemal defects may be caused by associated nonaxonemal components such as mitochondrial channels and illustrate that normal mitochondrial function is required for stability of the axoneme.

Animals↗
PubMed2001

Correlates of markers of oxidative status in the general population.

Oxidative stress has been implicated in the etiology of many chronic diseases, including cardiovascular disease. However, limited information exists on the factors that may influence oxidative status in the general population. In a random sample of the population of two counties in western New York, levels of several markers of oxidative status (i.e., thiobarbituric acid-reactive substances, erythrocyte glutathione, and glutathione peroxidase) were determined. A total of 894 men and 903 women aged 35-79 years were included in the study (1996-1999). In addition, a number of sociodemographic and lifestyle characteristics and cardiovascular disease risk factors were measured. Age, markers of glucose metabolism (e.g., plasma glucose level) and insulin resistance (e.g., serum triglycerides, high density lipoprotein cholesterol, body mass index), and postmenopausal status in women were associated with increased oxidative stress and reduced antioxidant potentials. Oxidative status and antioxidant potentials appear to be significantly associated with a number of major cardiovascular disease risk factors; most of them are linked to abnormalities in glucose and insulin metabolism.

Adult↗
PubMed2001

Dopamine D2 receptor dimer formation: evidence from ligand binding.

We have examined the binding of two radioligands ([(3)H]spiperone and [(3)H]raclopride) to D(2) dopamine receptors expressed in Chinese hamster ovary cells. In saturation binding experiments in the presence of sodium ions, both radioligands labeled a similar number of sites, whereas in the absence of sodium ions [(3)H]raclopride labeled about half the number of sites labeled by [(3)H]spiperone. In competition experiments in the absence of sodium ions, however, raclopride was able to inhibit [(3)H]spiperone binding fully. In saturation analyses with [(3)H]spiperone in the absence of sodium ions raclopride exerted noncompetitive effects, decreasing the number of sites labeled by the radioligand. These data are interpreted in terms of a model where the receptor exists as a dimer, and in the absence of sodium ions, raclopride exerts negative cooperativity across the dimer both for its own binding and the binding of spiperone. A model of the receptor has been produced that provides a good description of the experimental phenomena described here.

Animals↗
PubMed2001

Expression of Mig (monokine induced by interferon-gamma) is important in T lymphocyte recruitment and host defense following viral infection of the central nervous system.

Induction of a Th1 immune response against viral infection of the CNS is important in contributing to viral clearance. The present studies demonstrate a role for the T cell chemoattractant chemokine Mig (monokine induced by IFN-gamma) in contributing to a Th1 response against mouse hepatitis virus infection of the CNS. Analysis of the kinetics of Mig expression revealed mRNA transcripts present at days 7 and 12 postinfection (p.i.) but not early (day 2) or late (day 35) in the infection. To determine functional significance, mouse hepatitis virus-infected mice were treated with anti-Mig antisera, and the severity of disease was evaluated. Such treatment resulted in a marked increase in mortality that correlated with a >3 log increase in viral burden within the brains as compared with control mice treated with normal rabbit serum. Anti-Mig-treated mice displayed a significant decrease (p < 0.005) in CD4(+) and CD8(+) T cell recruitment into the CNS as compared with normal rabbit serum-treated mice. In addition, anti-Mig treatment resulted in a significant decrease (p < 0.05) in levels of IFN-gamma and IFN-beta that coincided with increased (p < 0.02) expression of the anti-inflammatory Th2 cytokine IL-10 within the CNS. Collectively, these data indicate that Mig is important in contributing to host defense by promoting a protective Th1 response against viral infection of the CNS.

Amino Acid Sequence↗
PubMed2001

Relief of central airways obstruction following spinal release in a patient with idiopathic scoliosis.

SUMMARY. Patients with idiopathic scoliosis are reported to have a restrictive pattern on pulmonary function tests. A case is presented of a teenage girl with juvenile idiopathic scoliosis who had evidence of airways obstruction in addition to restriction on pulmonary function tests (PFT). Examination of flow-volume loops suggested central airways obstruction. At the time of induction of anesthesia for the initial spinal release surgery, a double-lumen endotracheal tube could not be passed, despite fiberoptic visualization, because of extreme deviation of the left main-stem bronchus. Postoperatively, PFT demonstrated improved flows at high lung volumes and normalization of the shape of the flow volume loop. We suggest that preoperative PFT may be used to predict which patients have central airways obstruction. This may lessen unanticipated problems with intubation at the time of surgery and may identify patients who may expect immediate improvement in lung function after scoliosis repair.

Adolescent↗
PubMed2001

Benign outcome of RSV infection in children with cancer.

BACKGROUND: High case-fatality rates have been reported among adults who develop respiratory syncytial virus (RSV) infection while being treated for oncologic diseases, particularly after bone marrow transplantation. Previous reports of RSV infection among children with primary and acquired immunodeficiencies describe increased morbidity compared with that seen in immunocompetent children, but there have been few reports describing the outcome of RSV infection specifically among pediatric oncology patients. METHODS: We retrospectively reviewed the charts of all children being treated by the Pediatric Oncology Service at Memorial Sloan-Kettering Cancer Center who had positive tests for RSV between the Fall of 1994 and the Spring of 1998. Patients on the BMT Service were excluded from this analysis. RESULTS: Eighteen RSV infections were identified among pediatric oncology patients, who were being treated with aggressive, predominantly alkylator-based chemotherapy for a variety of oncologic diagnoses. Nine episodes of RSV infection (50%) were treated with specific antiviral therapy. Only one death less than 100 days from the diagnosis of RSV infection occurred among these 18 patients and was attributed to progressive leukemia. The remaining patients recovered fully, although three were readmitted with respiratory symptoms within two weeks of discharge. Seven patients had concurrent infection with other pathogenic organisms. CONCLUSIONS: In striking contrast with the outcome of RSV infection in adult oncology patients, there may be low mortality associated with RSV infection in pediatric oncology patients. It is possible that scheduled anti-neoplastic therapy need not be delayed for these patients when the diagnosis of RSV infection is made.

Adolescent↗
PubMed2001

Local fundus response to blue (LED and laser) and infrared (LED and laser) sources.

Light damage research began during the early years of laser light exploration. There is a clear and significant literature that identifies an easily demonstrated retina-pigment epithelium pathology which is associated with short wavelength exposures below 520 nm. Recent interest has expanded because of the growing evidence for a blue light contribution to the retina aging process by way of a poorly understood chemical process(es) that involve circulation, oxidative reactions and the spectral absorption properties of the pigment epithelium. New powerful sources of relatively inexpensive blue energy have become available as a family of light emitting diodes. In this experiment, we examined funduscopic, angiographic and scanning laser tomographic measures of the retinal-pigment epithelium response to LED and laser spectral blue and infrared emissions closely matched in wavelengths and delivered under carefully matched circumstances. Ten retinas in normal young rhesus monkeys were locally exposed to various energy density values at 458 nm (Argon laser) ranging from 5 to 54 J cm(-2). Eight rhesus eyes were exposed to LED irradiation with a peak wavelength of 460 nm ranging from 9 to 62 J cm(-2). Similarly, a matched infrared (IR) laser and IR LED pair were used to expose an additional ten eyes for comparison of the long wavelengths. IR irradiance ranged from 21 to 306 J cm(-2). There was no response to IR exposure in any of the eyes. Blue light exposure results were measured from the color fundus photographs, scanning laser tomographs and early- and late-phase fluorescein angiogram responses at 2 and 30 days after the exposure. Results scores were accumulated for the four measures at the two time periods. The resulting lesion scores when plotted against the exposure in J cm(-2)showed no demonstrable effect at irradiance lower than 10 J cm(-2)and near 100% effectiveness for irradiance greater than 30 J cm(-2). The most sensitive and enduring indicator of change was the late fluorescein angiograms. Nonparametric statistical analysis of the scores from the two samples support the conclusion that there is no difference in the consequences of LED and laser light exposures under these matched conditions.

Analysis of Variance↗
PubMed2001

An integrative review of pressure relief in surgical patients.

Effective patient positioning has been an important issue throughout the history of the nursing profession. Pressure ulcers result from prolonged pressure, which causes skin, tissue, or muscle damage. Surgical patients present a unique challenge in preventing pressure ulcers because they are immobile and unable to perceive the discomfort of prolonged pressure. The purpose of this integrative review is to examine risk factors associated with pressure ulcer development in surgical patients and to examine pressure-relieving support surfaces to determine if they significantly reduce intraoperative tissue pressure and result in a lower incidence of postoperative pressure ulcers. Most of the research focuses on long-term care units, with little attention given to the acute care setting. Although the pathophysiology and etiology of pressure ulcers are well documented by years of research, the OR as an etiologic factor is largely undefined.

Bedding and Linens↗