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Biomedical subjects

J Henson

Publications and source records attributed to J Henson.

At least 19 recordsLinked to original sources
PubMed2003

The need for radio-opaque side markers on CT of the paranasal sinuses.

AIM: To audit the presence of a radio-opaque "side marker" routinely placed on the right side of the face of all patients undergoing computed tomography (CT) of the paranasal sinuses in our hospital and to audit awareness levels amongst ear, nose and throat (ENT) clinical and theatre staff regarding the "marker". MATERIALS AND METHODS: An audit of 100 CT studies of the paranasal sinuses was carried out with regard to the presence or absence of the marker. A further audit was conducted relating to the awareness amongst ENT clinical staff and theatre nurses regarding the marker. Re-audit of a second cohort of 100 sinus CT studies was carried out after implementing changes indicated by the first audit cycle. Awareness amongst staff concerned was similarly re-audited. RESULTS: In audit cycle I the side marker was positively identified in 85% of the CT examinations and were deemed absent in 15%. Of the clinical staff interviewed, only 30% were aware of the presence of the "marker" and it's significance. In audit cycle II the "side marker" was positively identified in 100% of the scans reviewed. Awareness of the presence of the "marker" amongst clinical staff was found to be 90%. CONCLUSIONS: The routine placement of a radio-opaque side marker on the right zygoma of all patients undergoing CT of paranasal sinuses is a simple yet effective additional means of denoting the correct side whilst interpreting such images. This has important implications regarding surgery. The audit has shown an improvement in both the placement of the side marker as well as in awareness levels amongst staff involved to ensure best practice.

Awareness↗
PubMed2001

Low dose computed tomography in suspected acute renal colic.

AIM: To evaluate whether computed tomography (CT) of the renal tract in suspected renal colic using reduced exposure factors maintains diagnostic accuracy. METHODS: Prospective multi-centre cohort study. Patients with suspected renal colic were examined using computed tomography (CT) of the renal tract followed by intravenous urography (IVU) in four different centres with five different CT systems. RESULTS: Sixty-nine patients with suspected renal colic had CT of the renal tract followed by IVU. CT was performed with reduced exposure factors, giving a mean CT effective dose of 3.5 (range 2.8-4.5) mSv compared with 1.5 mSv for IVU. Ureteric calculi were detected in 43 patients: CT and IVU detected 40 (93%) ureteric calculi. CT identified other lesions causing symptoms in five patients and identified renal calculi in 24 patients. IVU identified renal calculi in six patients and made false positive diagnosis of renal calculi in seven patients. Mean examination time for CT was 5 minutes and for IVU was 80 minutes. CONCLUSION: CT examination at reduced exposure factors maintains the diagnostic accuracy recorded in other series.

Acute Disease↗
PubMed1998

Excretory transport of xenobiotics by dogfish shark rectal gland tubules.

Marine elasmobranch rectal gland is a specialized, osmoregulatory organ composed of numerous blind-ended, branched tubules emptying into a central duct. To date, NaCl excretion has been its only described function. Here we use isolated rectal gland tubule fragments from dogfish shark (Squalus acanthias), fluorescent xenobiotics, and confocal microscopy to describe a second function, xenobiotic excretion. Isolated rectal gland tubules rapidly transported the fluorescent organic anion sulforhodamine 101 from bath to lumen. Luminal accumulation was concentrative, saturable, and inhibited by cyclosporin A (CSA), chlorodinitrobenzene, leukotriene C4, and KCN. Inhibitors of renal organic anion transport (probenecid, p-aminohippurate), organic cation transport (tetraethylammonium and verapamil), and P-glycoprotein (verapamil) were without effect. Cellular accumulation of sulforhodamine 101 was not concentrative, saturable, or inhibitable. Rectal gland tubules did not secrete fluorescein, daunomycin, or a fluorescent CSA derivative. Finally, frozen rectal gland sections stained with an antibody to a hepatic canalicular multispecific organic anion transporter (cMOAT or MRP2) showed heavy and specific staining on the luminal membrane of the epithelial cells. We conclude that rectal gland is capable of active and specific excretion of xenobiotics and that such transport is mediated by a shark analog of MRP2, an ATP-driven xenobiotic transporter, but not by P-glycoprotein.

Animals↗
PubMed1992

The transcription factor Sp1 binds to the JC virus promoter and is selectively expressed in glial cells in human brain.

JC virus is a human DNA virus that specifically infects oligodendroglial cells, resulting in a demyelinating disease (progressive multifocal leukoencephalopathy) of the central nervous system of immunosuppressed patients. The host-range restriction of JC virus is controlled at the level of viral gene transcription. To analyze further the determinants of glial specificity, we cloned and sequenced the JC viral early promoter elements directly from the infected brain tissue of four patients. The promoter of each isolate contained a novel identical sequence, 5'-AGGGAGGAGC (GA box), located immediately upstream of the TATA box. This GA box is not present in the original isolate of JC virus (Mad-1 strain), which was obtained after numerous passages in tissue culture. The GA box has 80% homology with the consensus binding site for the transcription factor Sp1. Using a gel retardation assay, we found that Sp1 binds to the GA box. Alteration of bases within the sequence abolished binding of Sp1, demonstrating sequence specificity of binding. Immunohistochemical localization of Sp1 expression in human brain reveals that expression is restricted to the nuclei of oligodendroglial cells, cerebellar basket cells, and endothelial cells. The GA box is present in the promoters of the myelin basic protein and proteolipid protein genes. On the basis of these observations, we suggest that this Sp1-like binding site participates in the control of glial-specific gene expression.

Base Sequence↗
PubMed1992

Extraneural metastases in ependymoma.

Ependymomas, glial neoplasms usually arising in the posterior fossa or spinal cord, rarely metastasize outside the central nervous system. We have reviewed all 81 ependymomas evaluated at MSKCC between 1956-1989. Five (6.2%) had extraneural metastases (ENM). The primary tumor was in spinal cord in 3 patients and the cerebral hemisphere in 2. Two tumors were histologically anaplastic; 3 were histologically benign. The 5 patients were 3, 3, 3.5, 16 and 37 years old. Time from initial diagnosis to development of ENM was 0, 15, 35, 40, and 288 months. At the time of ENM the primary tumor was progressing in 4/5 patients. Prior therapy had included resection plus radiation therapy (RT) (1), RT plus chemotherapy (1), resection plus RT plus chemotherapy (2). One patient had not received prior therapy because ENM were present at diagnosis. The sites of ENM included lung and thoracic lymph nodes (2), pleura and peritoneum (2), and liver (1). Both patients with peritoneal ENM had had ventriculoperitoneal shunts. ENM did not correlate with histologic grade, age, or degree of surgical resection. When patients with ependymoma develop signs or symptoms of systemic disease such as abdominal pain, cough, or adenopathy, ENM should be considered.

Adolescent↗
PubMed1991

HuD, a paraneoplastic encephalomyelitis antigen, contains RNA-binding domains and is homologous to Elav and Sex-lethal.

A neuronal antigen (HuD) recognized by the sera of patients with antibody-associated paraneoplastic encephalomyelitis has been isolated by screening a lambda cerebellar expression library. The recombinant antigen provides an unambiguous assay for this rare condition associated with small cell lung cancer. The recombinant antigen has been used to identify specific infiltrating lymphocytes in tumors and affected brain tissues of patients with antibody-associated paraneoplastic encephalomyelitis and sensory neuronopathy. HuD mRNA is uniquely expressed in brain tissue. The HuD protein shows a remarkable homology to the Drosophila proteins Elav and Sex-lethal and is likely to play a role in neuron-specific RNA processing.

Amino Acid Sequence↗
PubMed1991

Characterization of sea urchin egg endoplasmic reticulum in cortical preparations.

The cortical endoplasmic reticulum (ER) of sea urchin eggs was localized on isolated egg cortices by staining with aqueous suspensions of the dicarbocyanine "DiI." Immunofluorescence localization of a calsequestrin-like protein was essentially identical; this is consistent with a role for the ER in calcium regulation. The ER often encircles cortical granules, making it well-suited for initiating fusion and propagating the calcium wave. Thiazole orange and Hoechst dye 33258 at pH 2 stain ribosomes bound to the ER, providing evidence that the cortical ER is rough ER. High chloride concentrations were found to disrupt ER continuity.

Animals↗
PubMed1991

Amplification of JC virus DNA from brain and cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy.

We have established an assay to detect JC viral DNA in brain tissue and CSF of patients with progressive multifocal leukoencephalopathy (PML) and amplified a 106-base pair segment of the gene encoding JC viral large T antigen by polymerase chain reaction (PCR) from the brains of eight patients with PML and from one of six CSF samples. Brain and CSF of patients without PML did not yield JC virus-specific DNA amplification products. Southern analysis documented that the sequences of the 106-base pair PCR product and JC viral DNA are identical. This assay can be used in the diagnosis of PML and to investigate the biology of JC virus.

Base Sequence↗
PubMed1988

Increased intrapulmonary retention of radiolabeled neutrophils in early oxygen toxicity.

Sequential lung injuries, such as oxygen toxicity followed by septicemia, are common during the adult respiratory distress syndrome (ARDS). As these forms of vascular injury may be mediated in part by polymorphonuclear leukocytes (PMN), aberrant interactions between PMN and previously injured pulmonary endothelium are of both theoretical interest and clinical importance. The present study was undertaken to test the hypothesis that early oxygen toxicity at a dose that injuries pulmonary endothelium relatively selectively alters intrapulmonary neutrophil kinetics. Unanesthetized rats breathing 1.0 atmospheres oxygen for 36 h showed ultrastructural endothelial damage but no edema, injury, or neutrophilic inflammation by histologic criteria. However, in these oxygen-toxic animals, whereas initial accumulation of radiolabeled PMN in lungs was normal, washout of PMN was abnormal at 120 min after infusion, at which point the pulmonary retention of radiolabeled PMN in the lungs of oxygen-treated animals was significantly higher than in control animals (139% of control, p less than 0.0096). Features of our methodology, including avoidance of osmotic stress and use of paired control animals, appear to have greatly enhanced the sensitivity of radiolabeled neutrophils for detecting a subtle abnormality of neutrophil-endothelial interactions. Our studies in the oxygen toxicity model provide the first demonstration in vivo of abnormal intrapulmonary neutrophil kinetics in early oxygen toxicity prior to the onset of histologic evidence of lung injury or inflammation.

Animals↗
PubMed1987

Severe pulmonary hypertension and arterial adventitial changes in newborn calves at 4,300 m.

Some human newborns have a syndrome characterized by irreversible pulmonary hypertension and severe hypoxemia and by medial hypertrophy and adventitial thickening of pulmonary arteries. We considered that newborn calves made severely hypoxic might reproduce features of the human disease. When 2-day-old calves were placed at 4,300 m simulated altitude, pulmonary arterial pressure was increased and could be reversed by 100% O2. However, after 2 wk at 4,300 m, pulmonary arterial pressures were suprasystemic and there was right-to-left shunting probably through the foramen ovale and a patent but restrictive ductus arteriosus. Suprasystemic pulmonary pressure and hypoxemia persisted with 100% O2 breathing. Morphometrical examination of the lung arteries showed a markedly thickened adventitia with cellular proliferation and collagen and elastin deposition. There was increased medial thickness and distal muscularization of the pulmonary arteries associated with decreased luminal diameter. The rapid development of severe pulmonary hypertension and poor responsiveness to O2 was associated with increased arterial wall thickness, particularly involving the adventitia. Thus the pulmonary arterial circulation in these calves, which were placed at high altitude for 2 wk, exhibited features resembling persistent pulmonary hypertension in newborn infants.

Altitude Sickness↗
PubMed1987

Disc damage above a spondylolisthesis.

Fifty-two patients with low back pain and spondylolisthesis at L5/S1 had discograms performed at the L4/L5 level. Retrolisthesis at L4/L5 occurred in 44%, but no direct relationship was demonstrated between the extent of retrolisthesis and either the grade of spondylolisthesis or the presence of disc damage. There was an inverse relationship between the degree of spondylolisthesis and L4/L5 disc damage. Thirty-six patients were assessed for symptomatic pain reproduction during discography. Fourteen (39%) had normal nuclear morphology and no pain induction on injection. Twenty-two patients had disc damage and 11 (50%) had symptomatic pain induced by injection. These results were correlated with the discographic appearances.

Adolescent↗
PubMed1986

Pleural effusion causing unmatched ventilation defects in ventilation and perfusion scanning.

In a survey of patients who had chest radiographs and ventilation and perfusion radionuclide scans, 20 patients had pleural thickening or effusion. Defects of ventilation unmatched with defects of perfusion occurred in 13 of the 20. This usually occurred if the fluid was freely mobile and was a result of the procedure adopted for imaging. Upon injection in the supine position, labelled albumin microspheres were trapped in the areas perfused at that time. Since, in this position, the effusion moved posteriorly, the bases of the lungs were better perfused than the dependent areas. On imaging in the erect position when the effusion was subpulmonary, the microspheres remained in the base but the ventilation was reduced, resulting in a mismatch in the basal regions. This appearance could be misinterpreted.

Humans↗