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Biomedical subjects

P Armstrong

Publications and source records attributed to P Armstrong.

At least 37 records · Page 2Linked to original sources
PubMed1999

Death and nonfatal reinfarction within the first 24 hours after presentation with an acute coronary syndrome: experience from GUSTO-IIb. Global Utilization of Strategies for Total Occlusion.

BACKGROUND: A large proportion of deaths among patients with myocardial infarction occurs within the first 24 hours after presentation. It is not clear whether this phenomenon is also true of patients without ST-segment elevation who may or may not have infarction at the time of presentation. Thrombin activity may also be greatest during the first 24 hours after plaque rupture. Accordingly, this study was designed to examine the pattern of early ischemic events among patients with acute coronary syndromes and to determine whether the direct thrombin inhibitor desirudin (r-hirudin) would be most effective during this period. METHODS AND RESULTS: Among the 11,142 patients enrolled in GUSTO-II, death or (re)infarction occurred within 24 hours in 210 patients (1.7%), representing 19% of the 1135 deaths that had occurred by 30 days. Death or (re)infarction occurred within 24 hours in 113 patients (2. 7%) with ST-segment elevation and in 97 patients without ST-segment elevation (1.2%, P <.001), representing 26% and 14% of the 30-day event rates, respectively, for the 2 enrollment strata. Among patients with ST-segment elevation, most of these events were deaths, whereas among patients without ST-segment elevation, most events were (re)infarctions. Death or (re)infarction by 24 hours occurred in 80 (1.3%) patients treated with desirudin and 130 (2.1%) patients treated with heparin (P =.01). This finding predominantly consisted of prevention of death among patients with ST-segment elevation and of (re)infarction among patients without ST-segment elevation. CONCLUSIONS: These findings have important implications for early triage of patients with acute coronary syndromes and for the development of new therapies directed at stabilizing the unstable atherosclerotic plaque.

Aged↗
PubMed1999

Baseline clinical characteristics of patients recruited into the assessment of treatment with lisinopril and survival study.

BACKGROUND: The beneficial effect of ACE inhibitors on mortality has been established in a series of trials. However, in clinical practice, ACE inhibitors are commonly administered in doses much lower than those shown to be effective in the landmark trials. AIMS: This report describes the baseline characteristics of the patients recruited into the ATLAS study by age and gender sub-groups. METHODS: The ATLAS study compared the effects of 'low' dose (2.5-5.0 mg/day) to 'high' dose (32.5-35.0 mg/day) lisinopril in a double-blind study of 3164 patients with moderate to severe heart failure and left ventricular ejection fraction < 30% during a mean follow-up period of 46 months. The primary end-point was all cause mortality and the principal secondary end-point a composite of all-cause hospitalisation or all-cause mortality. RESULTS: Among patients with heart failure selected for the presence of left ventricular systolic function there were few differences among age groups or between genders. Older patients were not so heavy, were more likely to have ischaemic heart disease, hypertension and atrial fibrillation contributing to their heart failure and had a higher blood urea. Women were not so heavy as men. Age and gender had no major influence on mean ejection fraction or baseline treatment in the ATLAS study. CONCLUSIONS: Weight and renal function may alter the plasma concentration of any given dose of an ACE inhibitor. Potential interactions between dose of lisinopril, weight and renal function will be explored after the study is completed.

Adult↗
PubMed1999

Allo-immunization elicits CD8+ T cell-derived chemokines, HIV suppressor factors and resistance to HIV infection in women.

We assessed the potential for an allogeneic-based vaccine against HIV infection in women who were allo-immunized with their partners' mononuclear leucocytes to prevent spontaneous recurrent abortion. Within 1 month of allo-immunization, there was significant upregulation in the concentrations of CD8 cell-derived suppressor factor activity, RANTES, and macrophage inflammatory proteins 1alpha and 1beta. Allo-immunization also downregulated the proportion of cells with CCR5 and CXCR4 receptors. We also found a dose-dependent decrease in HIV infectivity of CD4+ cells in vitro after allo-immunization with both primary and T-cell line adapted HIV-1. This study provides a rational basis for an alternative or complementary strategy of allo-immunization against HIV infection.

Abortion, Habitual↗
PubMed1999

Two consecutive outbreaks of Stenotrophomonas maltophilia (Xanthomonas maltophilia) in an intensive-care unit defined by restriction fragment-length polymorphism typing.

OBJECTIVE: To investigate and control consecutive outbreaks of Stenotrophomonas maltophilia infections in intensive-care-unit (ICU) patients. DESIGN: Epidemiological investigation; restriction fragment-length polymorphism typing by pulsed-field gel electrophoresis (PFGE) of genomic DNA of outbreak strains; institution of infection control measures to limit spread. SETTING: The medical-surgical ICU in an 800-bed tertiary-care center in Calgary, Alberta, Canada. RESULTS: S. maltophilia was recovered from 14 ICU patients (12 infected, 2 colonized) between February 1993 and February 1994. Ten of the 14 patient isolates and 1 environmental isolate were available for PFGE typing. Patient isolates from 6 of the first 10 patients were identical. Isolates from the next 3 of 4 patients and an isolate recovered from a ventilator being used by a patient not infected with S. maltophilia also were identical, but different from the first 6. The ventilator isolate was temporally associated with the latter 4 patients. CONCLUSION: Molecular typing allowed us to determine that there were two separate consecutive S maltophilia outbreaks rather than a single protracted outbreak. Recovery of S. maltophilia from patient ventilators and an in-line suction catheter suggests that the organism may have been spread by cross-contamination from contaminated equipment or from an environmental source.

Aged↗
PubMed1999

Role of MR imaging in the selection of patients with early cervical carcinoma for fertility-preserving surgery: initial experience.

PURPOSE: To assess whether magnetic resonance (MR) imaging can be used for reliable prediction of proximal extension of cervical carcinoma into the myometrium. MATERIALS AND METHODS: Thirty patients with early cervical carcinoma underwent MR imaging with use of a 1.5-T magnet prior to surgery. The MR images were analyzed by two radiologists, unaware of the histopathologic findings, for the relationship of the tumor to the internal os and extension of the tumor into the myometrium. Findings at MR imaging were compared with those at histopathologic examination. RESULTS: At MR imaging, 24 patients were considered not to have tumor extension proximal to the internal os and into the myometrium. All tumors were confirmed histopathologically. In six patients thought to have myometrial tumor invasion at MR imaging, five tumors were confirmed histopathologically; in one, tumor extended up to the internal os but did not involve the myometrium. CONCLUSION: This is a small study, but MR imaging appears accurate in the prediction of myometrial tumor involvement and in showing the relationship of cervical carcinoma to the internal os and, hence, the patient's suitability for trachelectomy.

Adult↗
PubMed1999

Hepatitis B vaccination of premature infants: a reassessment of current recommendations for delayed immunization.

OBJECTIVE: Current American Academy of Pediatrics and United States Public Health Service Immunization Practices Advisory Committee recommendations for hepatitis B immunization in premature infants weighing <2 kg at birth born to hepatitis B surface antigen (HBSAg)-negative mothers are to delay the initiation of vaccination until such infants reach 2 kg or until 2 months of age. This proposal to delay vaccination at birth in these low-risk infants was based on limited studies not conducted in the United States. We sought to reassess current recommendations to delay administration of hepatitis B vaccine in low-risk premature infants by determining the immunogenicity of early hepatitis B vaccination in a US population and identifying variables associated with poor immunogenicity. METHODS: A total of 148 infants <37 weeks' gestation born to mothers negative for HBSAg were recruited at birth and stratified to three birth weight groups: <1000 g, 1000 to 1500 g, and >1500 g. Recombinant hepatitis B vaccine was administered within the first week of life, at 1 to 2 months of age, and at 6 to 7 months of age. Serum obtained at birth and after the second and third doses of vaccine was tested for antibody to HBSAg. Variables associated with poor response were sought prospectively by collecting demographic and clinical data. RESULTS: A total of 118 subjects (83%) completed the study. Postsecond dose sera were available for 117 infants and postthird dose sera were available for 112 infants. The seroprotection rate (attaining >/=10 mIU/mL HBS antibody) after two doses was low (25%) regardless of birth weight; infants weighing <1000 g at birth had the poorest response (11%). The seroprotection response rate after three doses of vaccine increased with birth weight; infants weighing </=1500 g at birth (groups 1 and 2) had lower rates of response (52% and 68%, respectively) than did infants weighing >1500 g at birth (group 3; 84% response rate). The seroprotection response rate of group 3 infants after three doses of vaccine, although low, could not be differentiated from the response rates reported for full-term infants using 95% confidence intervals. Of all infants who did not achieve protective levels of antibody after three doses of vaccine, 96% (26/27) weighed <1700 g at birth. The geometric mean HBS antibody levels in responders were 88 and 386 mIU/mL after two and three doses, respectively. Of 36 children with a birth weight >1500 g, 33 (91%) achieved levels of HBS antibody >100 mIU/mL after three doses of vaccine, compared with 25/35 (71%) of infants with birth weight <1500 g. Using logistic regression analysis, nonresponders were more likely than were responders to have been treated with steroids (26% vs 9%) and to have had a low birth weight (1037 g vs 1455 g). In addition, the seroresponse rate of black infants was more likely than that of white infants to be associated with poor weight gain (falling off 2 percentile ranks in weight) in the first 6 months of life: 22% of black and 60% of white children who failed to gain weight adequately responded to vaccination, compared with 92% of black and 70% of white children who were growing adequately. Of interest, the only infant with a birth weight of >1700 g who did not make protective levels of specific antibody after three doses of vaccine was 2300 g at birth, but had inadequate weight gain in the first 6 months of life. CONCLUSIONS: This study supports current recommendations of the American Academy of Pediatrics and the Centers for Disease Control and Prevention for delaying the initiation of hepatitis B immunization beyond the first week of life for premature infants at low risk for hepatitis B infection, particularly in newborns weighing <1700 g at birth. In addition, we have identified variables other than birth weight that were associated with an inadequate immune response to early hepatitis B vaccination in premature infants, such as poor weight gain in the first 6 months of life

Analysis of Variance↗
PubMed1998

Chest imaging in AIDS.

A review of imaging in the acquired immune deficiency syndrome (AIDS) is presented. The imaging features can be conveniently categorized according to whether the presenting complications are infective (bacterial, protozoal, or fungal), bronchiectasis, neoplastic (Kaposi's sarcoma, AIDS-related lymphoma, or lymphoproliferative disease), or a miscellaneous group (non-specific interstitial pneumonitis, persistent generalized lymphadenopathy, or bronchogenic carcinoma).

AIDS-Related Opportunistic Infections↗
PubMed1997

Staging intrathoracic non-small-cell lung cancer.

This article outlines the ability of imaging techniques to stage intrathoracic non-small-cell lung cancer, particularly the extent of primary tumour (T stage), and the presence of nodal metastases (N stage). The detection of hilar and mediastinal lymph-node metastases by CT is covered initially, followed by an appraisal of MRI and radionuclide imaging techniques. Finally, the evaluation of mediastinal and chest-wall invasion by CT and MRI is described, and note is made of developing applications of ultrasound and endosonography. Computed tomography remains the standard technique, but its limitations are discussed, as is the value of other complementary imaging techniques.

Carcinoma, Non-Small-Cell Lung↗
PubMed1997

Patterns of prolapse in women with symptoms of pelvic floor weakness: assessment with MR imaging.

PURPOSE: To show the magnetic resonance (MR) imaging patterns of prolapse and to correlate them with symptoms in patients with constipation or fecal incontinence. MATERIALS AND METHODS: Thirty women underwent MR imaging with fast spoiled gradient-recalled acquisition in the steady state. The women were divided into three groups: 10 were asymptomatic volunteers, 10 had constipation, and 10 had fecal incontinence. Visceral prolapse and the configuration of the pelvic floor muscles were identified at rest and during straining. Visceral descent was compared between the three groups. RESULTS: Visceral prolapse was seen at multiple sites, most frequently in constipated patients. There was significantly greater bladder base descent (P < .01), uterocervical descent (P < .001), and puborectalis muscle ballooning (P < .05) in the group of constipated patients when compared with the group with fecal incontinence or the asymptomatic group. The degree of anorectal junction descent was significantly greater (P < .05) in the group of incontinent patients when compared with the asymptomatic group. CONCLUSION: MR imaging clearly shows pelvic visceral prolapse and pelvic floor configuration on straining. Prolapse frequently involves multiple sites in constipated patients, which is suggestive of global pelvic floor weakness. In contrast, the weakness is frequently posterior in fecally incontinent patients.

Adult↗
PubMed1997

MR appearances of desmoid tumors in familial adenomatous polyposis.

OBJECTIVE: The purpose of this study was to investigate the ability of MR imaging to show desmoid tumors in patients with familial adenomatous polyposis, to document the appearances of these tumors, and to identify possible predictors of growth. SUBJECTS AND METHODS: CT and MR imaging of 15 patients with familial adenomatous polyposis and known abdominal wall or intraabdominal desmoid tumors were performed. Nine patients underwent follow-up CT and MR imaging, and four patients had undergone CT within the previous 12 months. Unenhanced and gadolinium-enhanced T1-weighted MR imaging sequences and T2-weighted MR imaging sequences were performed, as was unenhanced and IV contrast-enhanced helical CT. The CT and MR images were independently assessed. RESULTS: CT revealed 35 desmoid tumors: 22 were intraabdominal and 13 were in the abdominal wall. MR imaging revealed 21 of the 22 intraabdominal desmoid tumors and 13 of the 13 abdominal wall desmoid tumors. MR imaging and CT findings agreed precisely on the site and margin of the intraabdominal and abdominal wall desmoid tumors. CT was more effective in revealing their relationship to the bowel. Contrast enhancement was more easily identified on MR images than on CT scans, especially when enhancement was inhomogeneous. High signal intensity on T2-weighted images was seen in eight desmoid tumors, all of which showed significant growth on follow-up scans. CONCLUSION: MR imaging can show both intraabdominal and abdominal wall desmoid tumors in patients with familial adenomatous polyposis. High signal intensity on T2-weighted images was seen from desmoid tumors that had shown marked growth on follow-up imaging.

Adenomatous Polyposis Coli↗
PubMed1997

Dynamic MR imaging compared with evacuation proctography when evaluating anorectal configuration and pelvic floor movement.

OBJECTIVE: The aim of this study was to determine the agreement between measurements of the anorectal configuration made with dynamic MR imaging and with evacuation proctography. SUBJECTS AND METHODS: Ten women with constipation were examined sequentially using both standard evacuation proctography and dynamic MR imaging. Correlation and agreement between standard measurements of anorectal configuration at rest and during straining or evacuation of the rectum were evaluated. RESULTS: Significant correlation existed for anorectal junction descent (r = .7, p = .023), change in the anorectal angle (r = .78, p = .008), the position of the rectal axis on straining (r = .62, p = .032), and rectocele depth (r = .82, p = .004). The mean of the measurement differences for anorectal junction descent as measured using the two techniques was -0.23 cm (SD, 1.40 cm). The mean of the measurement differences for change of the anorectal angle was +15.3 degrees (SD, 27.92 degrees). CONCLUSION: Standard measurements of anorectal configuration made using evacuation proctography and dynamic MR imaging show significant correlation. However, in our study statistical agreement was poor for measurement of anorectal junction descent and anorectal angle change as seen on imaging obtained with the two techniques.

Adult↗
PubMed1997

Magnetic resonance imaging of the pelvic floor in patients with obstructed defaecation.

BACKGROUND: Evacuation proctography and measurements of anorectal physiology are frequently used to clarify the pathophysiology of obstructed defaecation. In some patients these tests are normal, despite convincing clinical evidence of defaecatory difficulty. The aim of this study was to determine whether magnetic resonance imaging (MRI) could reveal pelvic floor abnormality in patients with obstructed defaecation. METHODS: Eleven women with obstructed defaecation, in whom evacuation proctography and anorectal physiology were normal, were examined by MRI, using a fast gradient echo sequence. Measurements of pelvic visceral and muscular descent were taken at rest and during straining, and compared with those obtained from 13 asymptomatic volunteers. RESULTS: Patients with obstructed defaecation had significantly greater pelvic visceral descent (P < 0.05), levator muscle descent (P = 0.04), levator plate angle change (P = 0.003) and increase in the area of the pelvic floor hiatus (P = 0.0002) than asymptomatic volunteers. CONCLUSION: MRI demonstrated marked pelvic visceral and levator muscle descent in women with obstructed defaecation, despite normal evacuation proctography and anorectal physiology. MRI should be considered if these examinations have been normal.

Adolescent↗
PubMed1996

Magnetic resonance imaging of adrenocortical adenomas in childhood: correlation with computed tomography and ultrasound.

There are few descriptions of the magnetic resonance (MR) appearance of hyperfunctioning adrenocortical tumours, particularly those occurring in childhood. We studied five patients, two girls and three boys, aged 6-14.3 years, presenting with clinical syndromes of adrenocortical hyperfunction. The diagnoses were Cushing's syndrome (n = 2), virilisation (n = 2), and Conn's syndrome (n = 1). Biochemical features suggested an adrenal lesion in each case. MR and ultrasound were performed in all five cases, with CT in four. Each patient had a functional adrenal tumour secreting either cortisol, androgens or aldosterone alone, or a combination of cortisol, androgens and oestradiol. The histological diagnosis was adenoma in four cases and tumour of indeterminate nature in one case. MR clearly showed the tumours (diameter 1.0-7.5 cm), all the lesions being of high signal intensity relative to liver on T2-weighted sequences. CT revealed an adrenal mass in each of the four patients scanned, three of which enhanced after intravenous contrast medium injection. The multiplanar imaging of MR allowed better distinction from adjacent structures and also demonstrated an unenlarged contralateral adrenal gland. In the patient with a 1-cm Conn's adenoma the lesion was more easily seen on MR than CT. Ultrasound showed the four larger tumours but was unable to visualise the contralateral adrenal or the Conn's adenoma. In conclusion, the MR appearances of four adrenocortical adenomas and one indeterminate tumour in children are described. MR has been found to be at least equal to CT in the detection of these tumours, with some possible advantages. Both techniques are superior to ultrasound.

Adenoma↗
PubMed1996

High resolution computed tomography in HIV patients with suspected Pneumocystis carinii pneumonia and a normal chest radiograph.

AIM: To correlate the appearances of high resolution computed tomography (HRCT) with the bronchoalveolar lavage (BAL) findings in HIV positive patients in whom there is a strong clinical suspicion of Pneumocystis carinii pneumonia (PCP) but a normal chest radiograph. PATIENTS AND METHODS: The 13 patients available for analysis fulfilled the following criteria: HIV positive, CD4 count less than 200 cells per mm3, non-productive cough or non-purulent sputum daily, documented fever above 37.5 degrees C for more than a week, dyspnoea or decreased exercise tolerance and normal chest X-ray. HRCT of the lungs was performed within 24 h of the chest radiograph, using 1 mm slice at 2 cm intervals, reconstructed using a high resolution algorithm. Bronchoalveolar lavage samples were taken for cytological examination, microscopy, culture and sensitivity. The HCRT findings were correlated with the results of BAL and clinical outcome. RESULTS: Of the 13 patients studied, four had patchy ground-glass opacities and one also had interstitial thickening. All four proved to have PCP on BAL. None of the nine patients who were negative for PCP on BAL had ground-glass opacity or abnormalities attributable to PCP. CONCLUSION: In this study HRCT showed abnormalities consistent with PCP in all four patients who had PCP on BAL before there were chest radiograph abnormalities. The use of HRCT may help avoid unnecessary delay, allow early medical intervention and, if our results are confirmed by larger series, may reduce the need for bronchoscopy.

AIDS-Related Opportunistic Infections↗
PubMed1996

Symptomatic human immunodeficiency virus (HIV) infection in Papua New Guinea.

BACKGROUND: Human Immunodeficiency Virus (HIV) infection was first detected in Papua New Guinea (PNG) in 1987. By August 1995 a total of 323 persons had been diagnosed as HIV antibody positive nationwide and seroprevalence rates were climbing. This study was prompted by a lack of data on the clinical syndromes associated with HIV infection in Melanesian adults. AIMS: To describe the clinical and epidemiological features of symptomatic HIV infection in adult Melanesians. METHODS: A largely retrospective study of patients was admitted to the medical wards of the Port Moresby general hospital between January 1990 and September 1995. Clinical records of patients with antibody to HIV were studied and clinical, laboratory and epidemiological data were recorded. RESULTS: Seventy patients were studied and the majority were young, urban dwelling adults from a variety of social groups. The sex distribution was even. Common clinical syndromes associated with HIV infection were chronic diarrhoea (47.8%), wasting (94.2%) and oropharyngeal candidiasis (68.7%). Tuberculosis was suspected in 68.6% and cryptococcal meningitis was detected in 8.6% including one patient with Cryptococcus. neoformans var. gattii infection. There was a high mortality (53%) in patients admitted to hospital. CONCLUSIONS: Patients with HIV infection in PNG present to hospital late in their disease course. Clinical syndromes are similar to those observed in Africa and mortality on first admission is high. The major mode of transmission is heterosexual and sexually transmitted diseases and promiscuity are probably important factors in facilitating spread.

Acquired Immunodeficiency Syndrome↗