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Biomedical subjects

J Halls

Publications and source records attributed to J Halls.

At least 19 recordsLinked to original sources
PubMed2004

The repair of gamma-ray-induced chromosomal damage in human lymphocytes after exposure to extremely low frequency electromagnetic fields.

G(0) human blood lymphocytes were irradiated with 2.0 Gy gamma-rays and cultured to metaphase whilst held in a 50-Hz power frequency magnetic field of 0.23, 0.47 or 0.7 mT. No differences were found in the frequencies of gamma-induced chromosome aberrations observed in cells held in the EM fields compared with replicates held in a sham coil. Similar field conditions have been reported to increase the frequency of gamma-induced HPRT mutations, leading to a suggestion that the EM fields alter the fidelity of repair of genomic lesions. This was not confirmed by the chromosome aberration assay described here.

Adult↗
PubMed2003

Possible associations between ELF electromagnetic fields, DNA damage response processes and childhood leukaemia.

Epidemiology has shown an association between exposure to extremely low frequency (ELF) electromagnetic fields (EMF) and childhood leukaemia. The causal nature and biological basis of this association are however questionable. Studies with aneuploid cell lines raised the hypothesis that ELF EMF may act as a coleukaemogen by compromising DNA damage response to genotoxic agents such as ionising radiation. We examined this hypothesis using gamma-ray-induced dicentric chromosome exchange in human lymphocytes. The results from 12 h post-gamma-ray exposure to fields of 0.23, 0.47 and 0.7 mT provide no support to the hypothesis. The power of the study was sufficient to exclude an ELF enhancement of chromosomal exchange of 10-15% (2SE).

Chromosome Aberrations↗
PubMed1999

Explaining women's intentions and use of hormones with menopause.

The purposes of this theoretically-based study were (a) to examine the contributions of psychosocial variables (i.e., affect, beliefs, and norms), habit, and facilitating conditions to explaining women's intentions and use of hormones with menopause and (b) to assess whether clinical or demographic factors explained intentions and use, when controlling for psychosocial, habit, and facilitating conditions variables. In a cross-sectional design, 184 pre-, peri-, and postmenopausal women completed questionnaire measures. To explain intentions, data from 124 participants who were not using hormones were analyzed. To explain use, data from 125 peri- and postmenopausal participants were analyzed. In multivariate analyses, anxiety was associated inversely with use; norms were associated positively with intentions and use. Age was associated inversely with intentions; hot flashes were associated inversely with use. Future researchers can examine the combined influences of affect, beliefs, and norms on decisions about hormones. Clinicians can address anxieties and assess social influences about hormone use, as well as offer ways to deal with hot flashes.

Anxiety↗
PubMed1993

Altered muscle metabolism shown by magnetic resonance spectroscopy in sickle cell disease with leg ulcers.

We performed 31P magnetic resonance spectroscopy of gastrocnemius muscle at rest in 7 normal volunteers and 12 patients with sickle cell disease (7 with leg ulcers and 5 without leg ulcers but with painful crises). We measured intracellular pH and ratios of Pi to ATP, PCr to ATP and PCr to Pi (Pi = inorganic phosphate, ATP = adenosine triphosphate, and PCr = phosphocreatine). Magnetic resonance arteriograms were also performed. Significant differences were found for PCr/Pi ratios between normals and sickle cell disease patients with leg ulcers (p < 0.008). Magnetic resonance arteriograms were normal in volunteers and patients with sickle cell disease. The altered high energy phosphate metabolism in sickle cell disease with leg ulcers is consistent with muscle ischemia or hypoxia.

Adult↗
PubMed1991

Radionuclide ventriculography in severely underweight anorexia nervosa patients before and during refeeding therapy.

Congestive heart failure is a well-recognized complication of refeeding therapy in underweight patients with anorexia nervosa but there are few data describing cardiac function during the critical refeeding period. This prospective study examined left ventricular function with conventional electrocardiographic-gated radionuclide ventriculography (RVG) in severely underweight anorexia nervosa patients both before and during refeeding therapy. Eight patients underwent rest and exercise RVG at admission and after regaining approximately 5% to 10% of their ideal body weight. With the admission study serving as a control, the left ventricular ejection fraction and regional wall motion analysis were analyzed before and after refeeding and weight gain. Resting left ventricular ejection fractions were not significantly different between the first and second RVGs (64 +/- 11% vs. 62 +/- 8%, respectively; P greater than .05). Likewise, the left ventricular ejection fraction with maximal exercise did not significantly differ when comparing the first or the second RVG (74 +/- 10% vs. 72 +/- 8%, P greater than .05). During the baseline RVG, the left ventricular ejection fraction increased from 64 +/- 11% (rest) to 74 +/- 10% (maximal exercise) (P less than .001). During the second RVG, the ejection fraction increased from 62 +/- 8% (rest) to 72 +/- 8% (maximal exercise) (P = .003). However, the left ventricular exercise ejection fraction in the second RVG in one patient increased only by one absolute percentage point. Four of the eight patients had regional wall motion abnormalities detected during resting and/or exercise RVG. Abnormal cardiac function occurs in asymptomatic patients with anorexia nervosa undergoing refeeding therapy.

Adolescent↗
PubMed1991

Color Doppler sonography in hepatocellular carcinoma.

Sixteen patients with hepatocellular carcinoma (HCC) were assessed with color Doppler sonography (CDS) for flow compared to normal hepatic parenchyma. Nine showed moderate increased flow, and two revealed marked increased flow. In most instances, the increased flow was peripheral. Color Doppler was also useful in assessing seven patients with portal vein invasion. In two instances, venous invasion was not detected on preliminary grayscale images. In another patient, hepatic venous invasion was suspected on grayscale images, but was shown to represent extrinsic compression only by color Doppler.

Carcinoma, Hepatocellular↗
PubMed1990

Effects of isosorbide dinitrate on the pattern of arterial blood flow in healthy human subjects.

1. Blood velocity measurements have been made in the superficial femoral artery, 10 cm downstream of the common femoral artery bifurcation, in healthy human subjects, using a multi-channel Doppler ultrasound device. 2. In a randomized double-blind protocol, the effects of isosorbide dinitrate were examined during a 2 h period. 3. The changes induced by isosorbide dinitrate include: (i) an increase in the width of the artery and a reduction in brachial arterial blood pressure, implying relaxation of arterial smooth muscle; (ii) an increase in reverse flow and a decrease in time-averaged mean velocity associated with a relatively small decrease of the velocity excursion during the cardiac cycle, implying an increase in flow pulsatility; and (iii) an alteration of the flow pattern both in the core and near the vessel walls.

Adult↗
PubMed1988

Guillain-Barré syndrome: diagnostic criteria, epidemiology, clinical course and prognosis.

Thirty-four patients were identified with Guillain-Barré syndrome (GBS) on review of 266 neuropathy cases admitted to a Copenhagen county hospital from June 1977 to January 1984. The age-adjusted incidence rate of GBS is 2.0 x 10(-5) years-1. The natural history of the disease, antecedent events, symptoms and signs, autonomic dysfunction, sequelae, CSF findings and mortality are described. Six cancer patients with GBS differed significantly from the non-cancer patients in a more protracted disease course and failure to improve. The National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) criteria for the diagnosis of GBS are discussed, and it is concluded that the criteria, although useful in comparative studies, are too restrictive when used in clinical practice.

Aged↗
PubMed1987

Medical treatment of hepatic amebic abscess: rare need for percutaneous drainage.

Although amebic liver abscess can virtually always be successfully treated medically, percutaneous drainage has been advocated recently. In 96 recently treated patients, therapeutic aspiration and percutaneous drainage were rarely needed. Most cases were correctly diagnosed by means of clinical, laboratory, and sonographic findings. Abscesses in only 13 (13.5%) patients were diagnostically aspirated. An abscess in one patient was therapeutically aspirated because the patient was responding slowly to medical therapy. No patient required catheter drainage. The key to successful amebic abscess management is medical therapy. Therapeutic drainage is rarely needed. Successfully treated patients occasionally respond slowly to medical therapy, and successfully treated amebic abscesses may enlarge or become bizarre-appearing on sonograms. This should not prompt therapeutic drainage. Diagnostic aspiration is appropriate when amebic and pyogenic abscesses are indistinguishable using clinical and imaging findings. Rare indications for therapeutic aspiration or drainage include pyogenic superinfection and large, juxtacardiac abscesses (potential intrapericardial rupture).

Chloroquine↗
PubMed1987

Sonographic features of amebic and pyogenic liver abscesses: a blinded comparison.

We blindly compared the sonographic findings in amebic (112 lesions) and pyogenic (30 lesions) liver abscesses. Two sonographic features were significantly more prevalent in amebic abscesses: the lesions had a round or oval shape and the lesions had an echogenicity that was lower than that of normal liver and were internally homogeneous on high-gain scans. Amebic abscesses were round or oval in 92 instances (82%), while 18 pyogenic abscesses (60%) (p less than .01) had these shapes. Fifty-nine (58%) of 101 amebic abscesses displayed low echogenicity and homogeneous internal echoes with high-gain settings compared with nine (36%) of 25 pyogenic abscesses (p less than .04). Despite these different sonographic patterns, image findings alone were inadequate in distinguishing pyogenic from amebic liver abscesses. However, when the sonographic findings were coupled with clinical and laboratory data, a correct diagnosis was possible in 83 (86%) of 96 patients with amebic abscess. It appears that, although some sonographic features of amebic abscess differ from those of pyogenic abscess, these differences are not sufficient to allow a specific diagnosis on the basis of sonography alone. Sonography can expedite abscess detection and, when coupled with clinical and laboratory data, can aid in differentiating pyogenic from amebic liver abscesses.

Humans↗
PubMed1983

Patterns of resolution in successfully treated hepatic amebic abscess: sonographic evaluation.

Gray-scale sonography has provided a means of following cases of successfully treated hepatic amebic abscess, allowing new insights into the natural history of this entity. In this study the majority of cases (23 of 32) resolved over a variable time period (1.5-23 months, median 7 months) to a normal sonographic hepatic parenchymal pattern. It is important that the transient, persistent abnormality seen after successful treatment not prompt reinstitution of therapy or further diagnostic testing in these patients. A smaller subgroup (six of 32) had sonographically persistent residua that appeared identical to benign simple cysts of the liver. The remaining three lesions showed slightly increased or decreased hepatic echogenicity after treatment.

Follow-Up Studies↗
PubMed1983

Posttraumatic intrahepatic biloma: sonographic diagnosis.

Posttraumatic intrahepatic biliary cysts or bilomas were once thought to be rare. With increased use of sonography and 99mTc-HIDA cholescintigraphy, this entity will probably be detected more often. Preoperative sonographic diagnosis of posttraumatic biloma was made in five patients. A well circumscribed, anechoic hepatic lesion with excellent distal sonic enhancement strongly suggests the diagnosis. Cholescintigraphy especially using delayed scans or percutaneous aspiration, can confirm the diagnosis.

Adult↗
PubMed1982

Prospective evaluation of the sonographic Murphy sign in suspected acute cholecystitis.

The sonographic Murphy sign, the presence of maximal tenderness elicited over a sonographically localized gallbladder, has been considered useful in the evaluation of patients with suspected acute cholecystitis. We prospectively evaluated this sign in 427 consecutive patients referred for evaluation of acute cholecystitis. The overall accuracy of the sonographic Murphy sign in the 219 patients with sufficient confirmation to be included in the statistical analysis was 87.2%. Sensitivity was 63% and specificity was 93.6%. The predictive value of a positive sign was 72.5%, while the predictive value of a negative sign was 90.5%. The sonographic Murphy sign is a useful, albeit imperfect, adjunct in the assessment of patients with suspected acute cholecystitis.

Acute Disease↗
PubMed1982

Sonography in the diagnosis and management of hepatic amebic abscess in children.

Hepatic amebic abscess is a potentially fatal infection which is difficult to diagnose in children. Sonography is an ideal non-invasive imaging tool which can prove invaluable in the diagnosis and management of hepatic amebic abscess. Sonographic findings should suggest the correct diagnosis in most instances. This allows prompt initiation of therapy, forestalling life-threatening complications. Sonography is also an extremely useful non-invasive means of following response to therapy in children with hepatic amebic abscesses.

Child↗