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Biomedical subjects

D Evans

Publications and source records attributed to D Evans.

At least 199 records · Page 11Linked to original sources
PubMed1994

Neonatal stroke: clinical characteristics and cerebral blood flow velocity measurements.

The clinical courses of 8 term infants with focal cerebral infarction or neonatal stroke were studied to determine whether such infants can be identified by current markers of perinatal distress, and whether changes in cerebral blood flow velocity (CBFV) occur during the acute phase of the disease. CBFV was measured from the middle cerebral artery (MCA) and anterior cerebral artery (ACA) utilizing duplex Doppler. Seven of the 8 patients required no resuscitation in the delivery room; 1 infant required brief bag and mask ventilation. No infant had evidence of severe fetal acidemia (i.e., cord pH < 7). All 8 infants were initially admitted to the newborn nursery. Infants were identified on the basis of abnormal clinical findings observed during the first 48 hours: seizures (n = 6) and hypotonia and apnea (n = 2). Serum electrolytes, calcium, magnesium, and glucose levels were normal, and the sepsis evaluation including a spinal tap was sterile in all patients. Neuroimaging revealed nonhemorrhagic left focal MCA infarction (n = 6) and right focal MCA infarction (n = 2). Duplex Doppler demonstrated transient ipsilateral decreases in CBFV as compared to the contralateral unaffected side at clinical presentation in 4 infants. In 2 of these infants the decrease in CBFV involved both the MCA and ACA, and in 2 infants, only the MCA vessels. These side-to-side differences were not present at subsequent CBFV measurements. The data indicate that infants who develop neonatal stroke cannot be distinguished from infants who do not develop the lesion by current markers of perinatal distress.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1994

Identification of M. tuberculosis ribosomal RNA in mouthwash samples from patients with tuberculosis.

It is often not possible to obtain satisfactory sputum samples from patients suspected of having pulmonary tuberculosis. In this study, we asked whether it was possible to identify M. tuberculosis ribosomal RNA (rRNA) in mouthwash samples, and in a prospective clinical study, whether the presence of this rRNA correlated with clinical M. tuberculosis infection. Using a combination of reverse transcriptase and polymerase chain reaction amplification, it was possible to identify M. tuberculosis rRNA in mouthwash samples. M. tuberculosis rRNA was identified in mouthwash samples from patients with active tuberculosis more commonly than in samples from control subjects (P < 0.05). The test was positive in four of ten patients with active pulmonary tuberculosis, one of eight contacts, none of eight past cases of tuberculosis, two of eight patients with other diagnosis and one of five healthy volunteers. M. tuberculosis rRNA was identified in sputum from four of eight patients and in bronchoscopy trap samples from four of five patients with active tuberculosis. However, one of ten sputum samples and two of five bronchoscopy samples from subjects with a clinical diagnosis other than active tuberculosis were positive. These results indicate that although it is technically possible to identify M. tuberculosis on the basis of the presence of rRNA in mouthwash samples, the poor sensitivity and specificity of the technique suggest that it is unlikely to be useful clinically.

Base Sequence↗
PubMed1994

The use of position during critical illness: current practice and review of the literature.

This descriptive study looked at how nurses positioned the critically ill person in the Intensive Care Unit. Its objective was to identify what positions were utilised, and whether severity of illness influenced this choice. The findings show nurses are conservative in their use of position during critical illness. There was only limited use of elevation of the backrest of the bed or rotation to the side during the side lying position. As the severity of illness increased, more horizontal positions were utilised. These findings and review of the literature highlights a need for further research into specific aspects of the use of position during critical illness.

Critical Care↗
PubMed1994

Controlling schistosomiasis: the cost-effectiveness of alternative delivery strategies.

Sustainable schistosomiasis control cannot be based on large-scale vertical treatment strategies in most endemic countries, yet little is known about the costs and effectiveness of more affordable options. This paper presents calculations of the cost-effectiveness of two forms of chemotherapy targeted at school-children and compares them with chemotherapy integrated into the routine activities of the primary health care system. The focus is on Schistosoma haematobium. Economic and epidemiological data are taken from the Kilombero District of Tanzania. The paper also develops a framework for possible use by programme managers to evaluate similar options in different epidemiological settings. The results suggest that all three options are more affordable and sustainable than the vertical strategies for which cost data are available in the literature. Passive testing and treatment through primary health facilities proved the most effective and cost-effective option given the screening and compliance rates observed in the Kilombero District.

Child↗
PubMed1994

Magnetic resonance imaging and spectroscopy of small ring-enhancing lesions using a rat glioma model.

RATIONALE AND OBJECTIVES: We sought to demonstrate the usefulness of proton and fluorine magnetic resonance spectroscopy (MRS) techniques in characterizing small ring enhancing lesions produced by experimental malignant gliomas. METHODS: The growth characteristics of a rat glioma model (RT2) were studied using contrast-enhanced magnetic resonance imaging scans of the tumors and histologic correlates obtained at various times. Changes in tumor metabolite levels were monitored on a serial basis using water-suppressed proton spectroscopy. The existence of tumor hypoxia was established using 19F MRS in combination with a fluorinated nitroimidazole and subsequently confirmed by immunohistochemical staining of tumor sections. RESULTS: Ring-enhancing lesions are produced by RT2 rat brain gliomas approximately 7 days after intracerebral implantation. Beginning at day 5, marked deviations in brain metabolite levels are observed on proton MR spectra. However, while the signal from the fluorinated nitroimidazole is first detected by 19F MRS at day 7, immunohistochemical staining of tissue sections reveals bound drug as early as day 5, when the first histologic signs of necrosis become apparent. CONCLUSIONS: Magnetic resonance imaging of RT2 rat brain glioma exhibits ring-enhancing characteristics similar to those observed in clinical studies. The appearance of the ring enhancement corresponds with the development of central necrosis and could serve as an indicator for rapid growth. Proton and fluorine MRS may be useful in confirming that a small ring-enhancing lesion represents an active tumor process early in its development.

Animals↗
PubMed1994

The construction and characterization of poliovirus antigen chimeras presenting defined regions of the human T lymphocyte marker CD4.

Defined regions of the CDR2-like region of the T cell antigen CD4 that are implicated in the binding of the surface glycoprotein (gp120) of human immunodeficiency virus type 1 (HIV-1) to CD4+ T lymphocytes have been engineered in place of antigenic site 1 of Sabin type 1 poliovirus. The antigenic properties of the recovered chimeric virus particles were investigated using monoclonal antibodies (MAbs) and polyclonal serum to CD4. None of the MAbs tested neutralized the chimeras, presumably because they are directed against conformational determinants of the V1 domain of CD4. In contrast, the three antigen chimeras were neutralized by polyclonal serum to CD4, which suggested that the CD4-derived sequences were presented in a relevant conformation. A panel of six MAbs were raised against one of the chimeras, and the epitopes were mapped by the selection of neutralization-resistant mutants and cross-neutralization studies. Five of the six MAbs reacted with soluble CD4 (sCD4) in ELISA, and one (MAb 1686) bound to CD4 expressed at the surface of HeLa cells. The high affinity interaction between gp120 and sCD4 was not blocked by MAb 1686, and the poliovirus-CD4 chimeras did not interact with gp120. These results demonstrate that poliovirus can be used as an epitope expression vector for the presentation of sequences in an immunodominant location on the virus particle which adopt a native or near-native conformation, and supports the findings of previous studies involving the presentation of epitopes derived from pathogens.

Amino Acid Sequence↗
PubMed1994

The cost-effectiveness of different blood-cholesterol-lowering strategies in the prevention of coronary heart disease.

We aimed to compare the cost-effectiveness of two screening strategies and a population strategy for lowering blood cholesterol to prevent coronary heart disease. Census data, known risk-factor profiles, known coronary heart disease event rates and costs in 1988-89 Australian dollars for all men aged 35 to 64 in the Lower Hunter region of New South Wales (n = 67,651) were used to compare a high-risk strategy identifying and treating men with cholesterol levels above 6.5 mmol/L with diet and drug (cholestyramine), a moderate/high-risk strategy where in addition diet counselling was offered to those with levels 5.5 to 6.5 mmol/L, and a population strategy where the diet of the whole population was changed regardless of blood cholesterol. Costs of implementing strategies, heart disease events saved, discounted and undiscounted cost-effectiveness ratios and savings in initial treatment costs over five years were measured. For the high-risk, moderate/high-risk and population strategies, the costs of implementation were $50.1m, $53.1m and $5.4m respectively; the numbers of events saved were 104, 144, 116 respectively; cost-effectiveness ratios were $482,224, $369,098, $46,667 (per event saved) respectively. Cost savings for each strategy were approximately half a million dollars. The moderate/high-risk strategy was more cost-effective than the high-risk strategy but the population strategy cost one-tenth that of the two screening strategies per event saved. More research is required to design and test strategies that alter the eating habits of the whole population.

Adult↗
PubMed1994

Apoptosis: a mechanism of cell killing by influenza A and B viruses.

In previous studies, we observed that the virulent avian influenza A virus A/Turkey/Ontario/7732/66 (Ty/Ont) induced severe lymphoid depletion in vivo and rapidly killed an avian lymphocyte cell line (RP9) in vitro. In examining the mechanism of cell killing by this virus, we found that Ty/Ont induced fragmentation of the RP9 cellular DNA into a 200-bp ladder and caused ultrastructural changes characteristic of apoptotic cell death by 5 h after infection. We next determined that the ability to induce apoptosis was not unique to Ty/Ont. In fact, a variety of influenza A viruses (avian, equine, swine, and human), as well as human influenza B viruses, induced DNA fragmentation in a permissive mammalian cell line, Madin-Darby canine kidney (MDCK), and this correlated with the development of a cytopathic effect during viral infection. Since the proto-oncogene bcl-2 is a known inhibitor of apoptosis, we transfected MDCK cells with the human bcl-2 gene; these stably transfected cells (MDCKbcl-2) did not undergo DNA fragmentation after virus infection. In addition, cytotoxicity assays at 48 to 72 h after virus infection showed a high level of cell viability for MDCKbcl-2 compared with a markedly lower level of viability for MDCK cells. These studies indicate that influenza A and B viruses induce apoptosis in cell cultures; thus, apoptosis may represent a general mechanism of cell death in hosts infected with influenza viruses.

Animals↗
PubMed1994

A new method of estimating cost effectiveness of cholesterol reduction therapy for prevention of heart disease.

The purpose of this study was to demonstrate a new method of estimating the cost effectiveness of interventions that lower blood cholesterol levels in the prevention of coronary heart disease (CHD) at the community level. The participants in the study were 67 651 men aged 35 to 64 years in the Lower Hunter region of New South Wales, Australia. Census data, risk factor profiles and CHD event rates from community surveillance, plus costs in 1988-1989 Australian dollars, were used as inputs to a computer program that used a logistic equation. The output estimated the CHD events avoided and the cost effectiveness of an intervention that identified and treated men with cholesterol levels greater than 6.5 mmol/L with dietary modification and cholestyramine. The cost of implementation of the intervention was $A50.1 million to prevent 104 CHD events. The cost-effectiveness ratio was $A482 224 per CHD event avoided (SD = $A24 761) and the direct medical costs avoided were approximately $A500 000 over a 5-year period ($A4535.07 per CHD event avoided). Drug acquisition costs contributed substantially (88%) to the total costs of interventions that rely on screening to identify individuals with high cholesterol for intensive treatment.

Adult↗
PubMed1994

DSM-III-R training in master's-level counseling programs.

The DSM-III--R is used by the subdisciplines of mental health including psychiatry, psychology, and social work. Yet, of all subdisciplines, it has historically met the most resistance from the counseling profession. Until the early 1980s, discussion of the DSM in the counseling literature was taboo. It has only been in the last 10 years that counselors have begun to discuss the role of the DSM in counseling. The purpose of this investigation was to examine the actual extent of DSM-III--R training in counseling programs. Analysis suggested that the counseling programs have included training in psychiatric diagnosis, but this training continues to meet resistance as it is inconsistent within the curricula of such programs.

Counseling↗
PubMed1994

Patient and family management of asthma: theory-based techniques for the clinician.

Several model asthma education programs are available to improve patient self-management, and elements of these models are discussed as they relate to the teaching role of health-care providers. Self-regulation is being explored in current asthma education research, and preliminary findings of a study are presented that show self-regulation behaviors to be associated with more frequent use of asthma management strategies by patients. Using more management strategies was associated with being observant of symptoms (p = .0001) and feeling confident to manage them (p = .01). Taking more preventive actions was associated with being observant (p = .001) and feeling confident to keep the child out of the triggering situation (p = .02) and prevent symptoms (p = .001). Important issues arising from recent psychosocial research are outlined for consideration by the clinician. These include ways that counseling by the health professional can encourage self-regulation and better at-home management of asthma.

Adult↗
PubMed1994

Long-arm Charnley splint.

Fractures of the distal forearm--the eponymic Colles' or Smith's fractures--are among the most common injuries treated by the orthopaedist. Most of these fractures are amenable to closed reduction and immobilization. A new modification of the Charnley splint is presented for use in the acutely injured patient. The major advantages of this new splint are decreased weight and ease of application.

Equipment Design↗
PubMed1994

The role of early MR in the evaluation of the term infant with seizures.

PURPOSE: To define the role of MR in evaluating term neonates with seizures the most common clinical manifestation of cerebral injury in neonates. METHODS: Fifteen term infants with seizures underwent MR imaging. The presence and pattern of MR findings were compared with clinical markers of perinatal distress, cause of cerebral injury, and short-term neurologic outcome. RESULTS: Seizures were caused by hypoxic-ischemic encephalopathy in three patients, bacterial meningitis in three, and prenatal cocaine exposure in one. Nine patients had no identifiable risk factors. By MR, five patients had focal ischemic injury of the cerebral hemispheres and/or basal ganglia and brain stem. Six patients had diffuse cerebral edema: of these, five had basal ganglia edema; one had brain stem edema. One patient had superior sagittal sinus thrombosis with venous infarcts. Three patients had normal MR studies. There was no correlation between markers of perinatal distress, risk factors for seizures, and presence or pattern of MR findings. There was some correlation between MR findings of diffuse cerebral injury and neurologic outcome, and between MR findings of basal ganglia and brain stem abnormalities and neurologic outcome; these findings correlated with spasticity and hemiplegia at 6 to 24 months follow-up. CONCLUSION: The presence or pattern of MR findings does not appear to correlate with with clinical signs of perinatal distress or presumed causes of perinatal cerebral injury. Further investigation is needed to identify prospectively neonates with seizures who are at risk for significant neurologic morbidity.

Asphyxia Neonatorum↗
PubMed1994

Assessment of glass polyalkenoate restorations in primary molar teeth.

This study assess the suitability of glass polyalkenoate cement as a restorative material in primary molars, when placed by community dental officers in their own clinics. Nine officers placed the restorations and two assessors examined the restorations after one and three years, recording details of the success or failure of each restoration. A total of 635 glass polyalkenoate restorations were placed and, after one year, 149 (23.4%) of these had failed. Of the 359 available for examination after three years, a further 142 (22.4%) had failed, leaving 217 (42.7%) intact. This study shows that the major factor in the successful use of glass polyalkenoate cements as a restorative material in deciduous molars is the classification type of cavity. A significant number of Class II restorations failed within the first year. The study confirms that glass polyalkenoate cements provide a satisfactory means of restoring Class I cavities in primary teeth.

Chi-Square Distribution↗
PubMed1993

Preoperative and postoperative combination chemotherapy for potentially resectable gastric carcinoma.

BACKGROUND: Median survival of patients with local-regional gastric carcinoma is 10 months. Resection of the primary tumor and regional lymph nodes, with tumor-free margins (curative resection), has been the most effective treatment for local-regional gastric carcinoma. However, median survival of patients with curative resection of gastric carcinoma is 24 months, and the 5-year survival rate is about 20%. A single institution pilot study has established the feasibility of administering two courses of chemotherapy preoperatively and three courses postoperatively. In another study, a 15% pathologically documented complete response (pathologic complete response) has been reported in unresectable gastric carcinoma treated with etoposide, doxorubicin, and cisplatin. PURPOSE: Our purpose was to increase the curative resection rate in potentially resectable gastric carcinoma and to delay or eliminate micrometastases and thus improve survival. We also evaluated clinical and pathologic response to chemotherapy. METHODS: Forty-eight previously untreated patients with potentially resectable gastric carcinoma received a chemotherapy regimen (EAP) consisting of etoposide (120 mg/m2 intravenously over a 2-hour period on days 4, 5, and 6), doxorubicin (20 mg/m2 as a 10-minute intravenous infusion on days 1 and 7), and cisplatin (40 mg/m2 as a 1-hour intravenous infusion on days 2 and 8). Patients received three courses of chemotherapy before resection, and responding patients received two courses postoperatively. Clinical and pathologic response rates, toxicity, patterns of treatment failure, and survival times were assessed. RESULTS: A median of three courses (range, 1-5) of preoperative therapy was administered; six (12%) of the 48 patients had clinical complete response, and nine (19%) had partial response. Forty-one (85%) underwent surgery; 37 (90%) of these 41 (77% of the 48 patients) had a curative resection. There were no pathologic complete responses. Median survival for all patients is 15.5 months (range, 2-29+ months). Therapy was discontinued because of the toxic effects in one patient before surgery and in six patients after surgery. Doses were reduced in 37 patients (77%), mainly because of hematologic toxicity. Nineteen (40%) were hospitalized because of toxic effects, including 15 patients who developed fever with neutropenia. Grade 3 or 4 nausea and vomiting occurred in 15 patients and grade 3 or 4 diarrhea in seven patients. One death was directly related to chemotherapy. CONCLUSIONS: These data support that administration of preoperative and postoperative chemotherapy for local-regional gastric carcinoma is feasible in a multi-institutional setting. Our findings demonstrate that this EAP regimen is modestly active but is associated with substantial toxicity. IMPLICATIONS: Use of preoperative chemotherapy in resectable gastric carcinoma merits further evaluation, but more effective drug regimens will be required before a controlled trial is initiated.

Adenocarcinoma↗