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Biomedical subjects

J Palmer

Publications and source records attributed to J Palmer.

At least 55 records · Page 3Linked to original sources
PubMed2000

Descriptive epidemiology of physical activity in African-American women.

OBJECTIVES: We assessed walking for exercise and moderate and strenuous physical activity in relation to both demographic and health-related characteristics among African-American women from various parts of the United States who participate in the Black Women's Health Study. METHODS: The data were collected in 1995 by mail questionnaire from 64,524 U.S. black women aged 21 to 69 years. The 64,101 women who provided data on physical activity are the subjects of the present report. RESULTS: The present study revealed low levels of physical activity among the African-American women: 57% reported an hour or less per week walking for exercise, 18% reported moderate activity, and 61% reported strenuous physical activity. Strenuous physical activity increased with education. Higher levels of walking for exercise and moderate and strenuous activity were associated with higher levels of participation in strenuous exercise in high school. CONCLUSION: Physical activity levels are low in African-American women. Based on the findings of the present study it may be suggested that educational efforts to increase levels of physical activity should start at an early age.

Adult↗
PubMed2000

Automated interpretation of ventilation-perfusion lung scintigrams for the diagnosis of pulmonary embolism using artificial neural networks.

The purpose of this study was to develop a completely automated method for the interpretation of ventilation-perfusion (V-P) lung scintigrams used in the diagnosis of pulmonary embolism. An artificial neural network was trained for the diagnosis of pulmonary embolism using 18 automatically obtained features from each set of V-P scintigrams. The techniques used to process the images included their alignment to templates, the construction of quotient images based on the ventilation and perfusion images, and the calculation of measures describing V-P mismatches in the quotient images. The templates represented lungs of normal size and shape without any pathological changes. Images that could not be properly aligned to the templates were detected and excluded automatically. After exclusion of those V-P scintigrams not properly aligned to the templates, 478 V-P scintigrams remained in a training group of consecutive patients with suspected pulmonary embolism, and a further 87 V-P scintigrams formed a separate test group comprising patients who had undergone pulmonary angiography. The performance of the neural network, measured as the area under the receiver operating characteristic curve, was 0.87 (95% confidence limits 0.82-0.92) in the training group and 0.79 (0.69-0.88) in the test group. It is concluded that a completely automated method can be used for the interpretation of V-P scintigrams. The performance of this method is similar to others previously presented, whereby features were extracted manually.

Adolescent↗
PubMed2000

Littoral cell angioma with severe thrombocytopenia.

Littoral cell angioma (LCA) is a recently described splenic vascular tumor. We present a new case in a 62-year-old woman with severe thrombocytopenia and mild bleeding diathesis, but without palpable splenomegaly. Abdominal ultrasound and magnetic resonance showed multiple nodular images, suggesting splenic hemangiomas. A platelet kinetic study revealed a very short platelet survival. As the spleen was the site of platelet destruction, splenectomy was carried out. Histopathological and immunohistochemical data allowed a final diagnosis of LCA. Following splenectomy, the patient showed a transitory normalization of the platelet counts. Thrombocytopenia then reappeared but was moderate, without hemorrhagic diathesis. A second platelet kinetic study, performed 16 months post-splenectomy, showed hepatic platelet destruction. However, there were no macroscopic hepatic lesions in a second abdominal magnetic resonance study. This case illustrates the difficulties involved in determining the etiology of many peripheral thrombocytopenias.

Female↗
PubMed2000

Risk factors for hyperlipidemia in long-term pediatric renal transplant recipients.

Hyperlipidemia (HL) is a common problem in adult renal transplant (TP) recipients, contributing to an increased risk of cardiovascular disease and chronic TP nephropathy. There are multiple causes of HL post renal TP in adult patients, including pre TP HL, immunosuppressive agents, renal dysfunction, hypoalbuminemia secondary to nephrotic syndrome, obesity, and conditions that lead to end-stage renal disease (ESRD). We evaluated the incidence and risk factors of HL in 62 pediatric renal TP recipients (15.4+/-4.2 years, range-3.0-22.3 years) with long-term (6.7+/-3.1 years) functioning [glomerular filtration rate (GFR) 66.7+/-23.2 ml/min per 1.73 m(2)] allografts. The mean serum cholesterol (C) level was 205. 5+/-43.6 mg/dl. Thirty-two patients (51.6%) exhibited elevated serum C levels. The mean serum triglyceride (TG) level was 157.3+/-88.4 mg/dl. Serum TG levels were elevated in 32 patients (51.6%). In patients with elevated serum levels of either C or TG, the mean low-density lipoprotein level (LDL) was 138.6+/-44.1 mg/dl (normal <130 mg/dl) and the high-density lipoprotein (HDL) level 54.6+/-15.9 mg/dl (normal>34 mg/dl). Of those patients studied, 45.5% had high LDL levels, whereas 9.1% exhibited low HDL levels. The two risk factors for elevated serum C levels in our patient population were pre-TP HL and increased years since TP. The only risk factor for elevated serum TG levels was reduced GFR. A family history of HL had a significant deleterious impact upon serum levels of C (P=0.01), but did not affect serum TG levels (P=0.7). Years on dialysis prior to TP, history of prior TP, gender, body mass index, and disease leading to ESRD had no influence upon the development of post-TP HL. We conclude that post-renal TP HL is a significant problem in pediatric renal TP recipients.

Adolescent↗
PubMed2000

The transition from scotopic to photopic vision in 3-month-old infants and adults: an evaluation of the rod dominance hypothesis.

The scotopic to photopic transition was tested in adults and 12-week-old infants using a large field motion nulling technique at a series of luminances between -3.57 and 2.70 log cd m(-2). The stimuli were composed of 0.25 cyc deg(-1), 5.6 Hz blue/black and yellow/black sinusoidal grating components, superimposed and moving in opposite directions. The contrasts of the two components were traded off to determine motion nulls at each luminance level. An eye movement based response measure was used for infant subjects, whereas self-report was used in adults. In both age groups, the motion null values approached a scotopic asymptote consistent with V'(lambda) at the lowest luminance levels, and a photopic asymptote consistent with V(10)(lambda) at the highest luminance levels. The scotopic to photopic transition was gradual and occurred over about 3 log units between about -2 and 1 log cd m(-2) in both groups. The null values for infants and adults were highly similar at each luminance level, and the shapes of the transition curves were virtually identical at the two ages. These data suggest that at each different luminance level, the balance between rod-initiated and cone-initiated signals in the extrafoveal luminance channel is similar or identical in 12-week-old infants and adults.

Adaptation, Ocular↗
PubMed2000

The psychophysics of visual search.

Most theories of visual search emphasize issues of limited versus unlimited capacity and serial versus parallel processing. In the present article, we suggest a broader framework based on two principles, one empirical and one theoretical. The empirical principle is to focus on conditions at the intersection of visual search and the simple detection and discrimination paradigms of spatial vision. Such simple search conditions avoid artifacts and phenomena specific to more complex stimuli and tasks. The theoretical principle is to focus on the distinction between high and low threshold theory. While high threshold theory is largely discredited for simple detection and discrimination, it persists in the search literature. Furthermore, a low threshold theory such as signal detection theory can account for some of the phenomena attributed to limited capacity or serial processing. In the body of this article, we compare the predictions of high threshold theory and three versions of signal detection theory to the observed effects of manipulating set size, discriminability, number of targets, response bias, external noise, and distractor heterogeneity. For almost all cases, the results are inconsistent with high threshold theory and are consistent with all three versions of signal detection theory. In the Discussion, these simple theories are generalized to a larger domain that includes search asymmetry, multidimensional judgements including conjunction search, response time, search with multiple eye fixations and more general stimulus conditions. We conclude that low threshold theories can account for simple visual search without invoking mechanisms such as limited capacity or serial processing.

Discrimination, Psychological↗
PubMed2000

Development of a model for the detection and treatment of depression in primary care.

Development and implementation of a protocol for identifying and treating depressed patients in a busy, group model, HMO primary care practice is described. Initial results and barriers to implementation are reported. A simple depression screening tool was adapted and a protocol for using available primary care staff and resources was developed to efficiently integrate screening and treatment for depression into daily practice. Important components of the program included specification of the target population, adaptation of a patient self-report diagnostic and rating tool, a nurse-educator protocol for patient follow-up and telephone support, a database to track patient progress, training for primary care staff, and collaboration with specialty Behavioral Health Care. After piloting, plans were made for transferring the model to other practices. Although the protocol was seen as beneficial to the PCP, Nurses, and patients involved, the scarcity of resources in other primary care practices proved a major barrier to full implementation.

Behavioral Medicine↗
PubMed2000

Efficient lung scintigraphy.

Lung scintigraphy is a first-choice method to diagnose lung embolism. The clinical routine in most centres is a perfusion study complemented with a ventilation study when judged necessary. We describe a routine with ventilation scintigraphy preceding perfusion scintigraphy, which is completed within one hour. Furthermore, the data acquired allow the determination of lung clearance of the tracer 99mTc-DTPA (diethylene triamine penta-acetate) used for the ventilation scintigraphy. An aerosol generator charged once a day with 99mTc-DTPA solution is used for all inhalations during the day. Inhalation is monitored with a counter and interrupted when the count rate corresponds to about 20 MBq. The ventilation imaging starts and ends with posterior projections. This allows calculation of lung clearance of 99mTc-DTPA. Perfusion scintigraphy is performed in a standard fashion with 100 MBq of 99mTc-MAA (macro-aggregated albumin). The ventilation study was considered to give some diagnostic information in the majority of the patients. The clearance determination allows detection of inflammatory lung disease. The background activity caused by the ventilation study comprised only 13% of the activity in the perfusion scintigraphy and did not significantly interfere with interpretation of the perfusion scan. The cost for the investigation is low because of the rational system for aerosol administration and the short time for a complete study.

Humans↗
PubMed2000

Scandinavian test of artificial neural network for classification of myocardial perfusion images.

Artificial neural networks are systems of elementary computing units capable of learning from examples. They have been applied to automated interpretation of myocardial perfusion images and have been shown to perform even better than experienced physicians. It has been shown that physicians interpreting myocardial perfusion images benefit from the advice of such networks. These networks have been developed and validated in the same hospital. However, widespread use of neural networks will only take place if the networks can maintain a high accuracy in other hospitals, i.e. hospitals using different gamma cameras, different acquisition techniques, different study protocols, etc. The purpose of this study was to develop a neural network in one hospital and test it in another. An artificial neural network was trained to detect coronary artery disease using myocardial perfusion scintigrams from 135 patients at a Swedish hospital. Thereafter, this network was tested using scintigrams from 68 patients at a Danish hospital and compared to six criteria based on expert physician analysis and quantitative analysis by the CEqual program. The sensitivity of the network was significantly higher than that of one of the physician criteria (0. 92 versus 0.71) and two of the CEqual-based criteria (0.94 versus 0. 63 and 0.96 versus 0.65) compared at equal specificities. It was concluded that an artificial neural network can maintain high accuracy in a hospital other than the one where it was developed.

Coronary Disease↗
PubMed2000

Human amniotic fluid lacks interleukin-2 and interleukin-15 but can interact with the beta-chain of the interleukin-2 receptor.

The present study investigated whether an explanation for the conflicting reports on the interleukin-2 (IL-2) status of amniotic fluid is due to the presence of IL-15 which shares biological activities with IL-2 and utilizes the IL-2 receptor beta-chain. Amniotic fluids from 45 normally progressing pregnancies between 14 and 16 weeks after the last menstrual period were assayed for IL-2 and IL-15 by bioassay and enzyme-linked immunosorbent assay (ELISA). The ability of amniotic fluids to induce cytotoxic T lymphoblastoid line-2 (CTLL-2) cell proliferation was demonstrated to be dependent upon bioassay culture conditions. In serum-free medium each amniotic fluid stimulated CTLL-2 proliferation with a mean level of IL-2-like bioactivity of 14.7 +/- 2.3 ng/ml but amniotic fluids failed to induce CTLL-2 proliferation in serum-supplemented medium. Treatment with neutralizing anti-IL-2 or anti-IL-15 antibodies failed to inhibit amniotic fluid-induced CTLL cell proliferation in serum-free medium, indicating a lack of IL-2 and IL-15 bioactivity. In contrast, treatment with anti-IL-2 receptor beta-chain antibody significantly reduced amniotic fluid-induced proliferation. The lack of IL-2 and IL-15 activity in amniotic fluids was confirmed using ELISA. Although high levels of IL-15 immunoactivity were detected in all samples, specificity controls showed a lack of specific IL-15 immunoactivity in amniotic fluid. Pretreatment of amniotic fluids with 100-500 ng/ml mouse immunoglobulin G abrogated IL-15 immunoactivity, indicating that amniotic fluid contains molecules binding to Fc regions of immunoglobulins and responsible for false ELISA positivity. These studies unequivocally show that amniotic fluid lacks IL-2 and IL-15 but can stimulate CTLL-2 cell proliferation via the IL-2 receptor beta-chain. The absence of IL-2 and IL-15 in normal mid-trimester amniotic fluid suggests that the cytokine profile of human pregnancy appears to be associated with a bias against type 1 cytokines within the feto-placental unit.

Amniotic Fluid↗
PubMed2000

Ketoacidosis in young adults is not related to the islet antibodies at the diagnosis of Type 1 diabetes mellitus--a nationwide study.

AIMS: To test the hypothesis that there is lower prevalence of islet antibodies in subjects with newly diagnosed Type 1 diabetes mellitus in young adulthood than in children is associated with less severe diabetes at time of diagnosis. METHODS: This investigation was based on a nationwide study (Diabetes Incidence Study in Sweden) of 15-34-year-old newly diagnosed diabetic subjects. During 1992-1993, all diabetic subjects (excluding secondary and gestational diabetes) were reported on standardized forms, with information about clinical characteristics at diagnosis. The study examined islet cell antibodies (ICA) by indirect immunofluorescence, and autoantibodies to glutamic acid decarboxylase (GADA), tyrosine phosphatase-like antigen (IA-2A) and insulin (IAA) as well as C-peptide by radioimmunoassay. RESULTS: Blood samples were available from 78 patients with diabetic ketoacidosis (DKA) and 517 non-acidotic patients. The prevalence of ICA (63% vs. 57%), GADA (63% vs. 66%), IA-2A (35% vs. 44%) and IAA (20% vs. 15%) were very similar in patients with or without DKA. The median levels of the four autoantibodies did not differ between the two groups. High blood glucose (P < 0.001) and low C-peptide levels (P < 0.001) were the only parameters found to be related to DKA. CONCLUSIONS: The similarities in findings of newly diagnosed diabetic patients with or without DKA regarding ICA, GADA, IA-2A and IAA suggest that there is no relationship between the expression of antigenicity and the severity of beta-cell dysfunction. The lower prevalence of the four autoantibodies in 15-34-year-old diabetic subjects compared with previous findings in children is not explained by misclassification of diabetes type.

Adolescent↗
PubMed2000

Identification of MEN1 gene mutations in families with MEN 1 and related disorders.

Following identification of the MEN1 gene, we analysed patients from 12 MEN 1 families, 8 sporadic cases of MEN 1, and 13 patients with MEN 1-like symptoms (e.g. cases of familial isolated hyperparathyroidism (FIHPT), familial acromegaly, or atypical MEN 1 cases) for the presence of germline MEN1 mutations. The entire coding region of the MEN1 gene was sequenced, and mutations were detected in 11 MEN 1 families; one sporadic MEN 1 patient, one case of FIHPT and one MEN 1-like case. Constitutional DNA samples from individuals without MEN1 mutations were digested with several restriction enzymes, Southern blotted and probed with MEN1 cDNA to analyse for the presence of larger deletions of the MEN1 gene unable to be detected by PCR. One MEN 1 patient was found to carry such a deletion. This patient was heterozygous for the D418D polymorphism, however sequence analysis of RT-PCR products showed that only the variant allele was transcribed, thus confirming the result obtained by Southern analysis, which indicated loss of a region containing the initiation codon of one allele.

Acromegaly↗
PubMed2000

Identification of somatic mutations of the MEN1 gene in sporadic endocrine tumours.

Endocrine tumours of the pancreas, anterior pituitary or parathyroids arise either sporadically in the general population, or as a part of inherited syndromes such as multiple endocrine neoplasia type 1 (MEN 1). The mechanisms responsible for the development of sporadic endocrine lesions are not well understood, although loss of heterozygosity (LOH) of the MEN1 locus on chromosome 11q13 and somatic mutation of the MEN1 gene have been frequently associated with the development of MEN 1-type sporadic endocrine lesions. To further investigate the role of the MEN1 gene in sporadic endocrine tumorigenesis, we analysed DNA from 14 primary parathyroid lesions, 8 anterior pituitary tumours and 3 pancreatic tumours for the presence of somatic MEN1 gene mutations and LOH of seven microsatellite markers flanking the MEN1 locus. In addition, we similarly analysed 8 secondary parathyroid lesions which arose in patients with chronic renal failure. None of the patients studied had a family history of MEN 1. Three primary parathyroid lesions and one pancreatic tumour (glucagonoma) were found to have lost one allele at the MEN1 locus. Somatic mutations were identified by SSCP and sequence analysis in one of these parathyroid lesions (P320L) and in the glucagonoma (E179V). These results support previous findings that inactivation of the MEN1 tumour suppressor gene contributes to the development of sporadic MEN 1-type endocrine lesions but is not associated with the development of parathyroid hyperplasia seen in some renal failure patients.

Adenoma↗
PubMed2000

Management of raised intracranial pressure in children.

Children suffer a significant number of head injuries as a result of their high activity levels, immature developmental skills and increased head-to-body mass ratio. Primary brain injury is irreversible, but secondary insults can be limited. Central to this is the management of raised intracranial pressure (ICP). The pathophysiology of head injury can explain some of the causes of raised ICP. Monitoring of ICP is important and this is closely linked to the maintenance of an adequate cerebral perfusion pressure and the importance of normovolaemia. Other interventions that have been shown to limit rises in ICP are appropriate use of positioning, mechanical ventilation and drug therapy. Less common therapies include jugular venous bulb oxygen saturation monitoring and the use of trometamol (THAM). Most nursing interventions do not actively reduce ICP, but they are central to its management. Reducing stimuli, avoiding cluster care, manual hyperinflation and limiting routine endotracheal suction may prevent an accumulative rise in ICP. Based on this literature review, it is possible to divide these interventions into first and second tier treatments, as shown in the protocol. Much of the suggested management will occur simultaneously, but it is important to assess the child's own response to each intervention and thus tailor treatment to minimize secondary brain injury.

Age Factors↗
PubMed2000

Intra-abdominal hypertension and abdominal compartment syndrome in burn patients.

BACKGROUND: Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are known to occur in patients after major abdominal surgery. The incidence of IAH and ACS in the burn population is not known. METHODS: We prospectively recorded the intra-abdominal pressures of major burn patients admitted to our burn center from February 1999 to September 1999. A bladder pressure greater than 25 mm Hg was diagnosed as IAH. ACS was diagnosed when pulmonary compliance decreased in association with persistent IAH and was treated with abdominal decompression. RESULTS: Ten patients were placed on the protocol; of these, seven developed IAH. Five responded to conservative treatment. Two patients with 80% body surface area burns developed ACS and required decompression. CONCLUSIONS: IAH occurs commonly in major burn patients, and ACS is seen regularly in patients with more than 70% body surface area burns. We recommend bladder pressure measurements after infusion of more than 0.25 L/kg during the acute resuscitation phase and for peak inspiratory pressures greater than 40 cm H2O. Whereas ACS warrants surgical decompression of the abdominal cavity, IAH usually responds to conservative therapy.

Adult↗
PubMed2000

Nonseptic monoarthritis: imaging features with clinical and histopathologic correlation.

Diagnosis of septic arthritis requires aspiration and analysis of joint fluid. However, nonseptic articular disorders are fairly common and represent a significant diagnostic and therapeutic challenge. Such disorders include gout, Milwaukee shoulder, rapidly destructive articular disease, amyloid arthropathy, hemophilic arthropathy, primary synovial osteochondromatosis, pigmented villonodular synovitis, neuropathic arthropathy, and foreign-body synovitis. The clinical signs of articular disease, which include pain, swelling, and limitation of motion, are often nonspecific and can overlap with those of osseous or extraarticular disorders. Many articular processes have characteristic radiologic appearances that allow definitive diagnosis. Radiography is an important part of the evaluation of patients with articular disease. However, magnetic resonance (MR) imaging is the method of choice for characterizing the various disorders and assessing the full extent of osseous, chondral, and soft-tissue involvement. MR imaging can exquisitely demonstrate joint effusions, synovial proliferation, articular cartilage abnormalities, subchondral bone, ligaments, muscles, and juxtaarticular soft tissues. Although a wide spectrum of noninfectious processes may involve the joints, careful analysis of the imaging findings and correlation of these findings with the patient's clinical history can suggest a more specific diagnosis in most cases. Awareness and understanding of the underlying histopathologic findings aids in interpretation of MR images.

Adolescent↗