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Biomedical subjects

M A Farrell

Publications and source records attributed to M A Farrell.

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

A prospective comparison of magnetic resonance cholangiopancreatography with endoscopic retrograde cholangiopancreatography in the evaluation of patients with suspected biliary tract disease.

AIM: To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) compared with direct cholangiography in the detection of biliary tract disease. PATIENTS AND METHODS: MRCP was performed in 100 patients in whom direct cholangiographic correlation (ERCP, n = 98; PTC, n = 9; intraoperative cholangiography, n = 3) was available for comparison. The MRCP examinations were performed using a two-dimensional multi-slice, fast spin echo (FSE) technique and a local surface coil. The diagnoses at direct cholangiography were choledocholithiasis in 30 patients, benign and malignant strictures in 28 patients and normal bile ducts in 42 patients. The nature of the strictures (benign, n = 2; tumour, n = 18; lymphnode recurrence, n = 3; unknown histology, n = 5) was determined by one or more of the following procedures: surgery (n = 8), biopsy (n = 15), cytology (n = 6) and cross-sectional imaging/follow-up findings (n = 3). RESULTS: MRCP diagnosed choledocholithiasis with a sensitivity of 93%, specificity of 99% and accuracy of 97 %. It resulted in two false-negative and one false-positive findings when compared with direct cholangiography. MRCP accurately diagnosed the presence and level of strictures in all patients. The overall sensitivity, specificity and accuracy of MRCP in the detection of bile duct lesions were 97%, 98% and 97%, respectively. CONCLUSION: MRCP has a high diagnostic accuracy when compared with direct cholangiography in the detection of bile duct disease.

Adult↗
PubMed1999

Microspectrophotometric analysis of respiratory pigments using a novel fibre optic dip probe in microsamples.

A microspectrophotometer system to monitor the reduction of mitochondrial respiratory pigments in cell extracts and permeabilized cells has been developed. The novel optical fibre set-up uses visible spectrophotometry to measure the reduction of mitochondrial electron carriers. The basis of the system is an Ocean Optics S1000 spectrometer, a broadband tungsten based light source, input and output coupling fibre optics and a fibre optic dip-probe which requires less than 20 microl of sample for analysis. The spectral range of the system is from 250 to 850 nm with a spectral resolution of 0.5 nm. Data are presented for the reduction of purified cytochrome c by the reducing agent sodium dithionite and the reduction of cytochrome c by isolated mitochondria using sodium succinate as substrate. Reduction of cytochrome c by digitonin permeabilized cultured mouse cells, C2C12, is also shown. The effect of temperature on cytochrome c reduction in these assays is also demonstrated. The optical design of the probe system is optimized to maintain maximum light throughput and spectral resolution. The key features of the system are small sample size, front-end adaptability, high sensitivity and fast multispectral acquisition which are essential for observing these biological reactions in vivo.

Animals↗
PubMed1999

A three-dimensional gadolinium-enhanced MR venography technique for imaging central veins.

OBJECTIVE: We evaluated the use of a three-dimensional gadolinium-enhanced MR venography technique in selected patients with suspected central venous abnormalities. SUBJECTS AND METHODS: Thirty-seven patients with suspected thrombosis, stenosis, occlusion, or compression of the axillary vein, subclavian vein, brachiocephalic vein, or superior or inferior vena cava or with suspected malfunction of central venous catheters were imaged. For all patients, we obtained a three-dimensional dynamic gadolinium-enhanced (bolus injection, 30 40 ml) breath-hold spoiled gradient-recalled acquisition in the steady state as well as conventional venous images from either Doppler sonography, CT, or digital subtraction venography. Breathhold fast multiplanar spoiled gradient-recalled acquisitions in the steady state were obtained using the following parameters: TR/TE, 10.3/1.9; flip angle, 45 degrees; matrix size, 256 x 128; number of excitations, one; field of view, 36-48 cm; number of partitions, 28; and slice thickness, 2.54 mm. MR venograms and conventional images were interpreted by two observers in consensus who were unaware of clinical information and the diagnosis. RESULTS: MR venograms were of diagnostic quality for all 37 patients. Thirteen patients had normal venous systems seen on both conventional and MR images. MR venography showed all nine venous stenoses, the one pericatheter fibrin sheath, and the one jugular vein thrombosis. Axillary or subclavian vein thrombosis was correctly diagnosed with MR venography in all four patients with this condition. Mediastinal venous compression was accurately depicted by MR venography in the five patients who had such compression. Finally, MR venography revealed the correct diagnosis in the three patients with inferior vena cava thrombus and tumor and the one patient with inferior vena cava compression. Thus, MR venography was 100% sensitive, specific, and accurate in the diagnosis of abnormalities affecting large central veins. CONCLUSION: Compared with conventional imaging, gadolinium-enhanced breathhold MR venography is easy to perform, well tolerated, and highly accurate in depicting central venous abnormalities.

Adult↗
PubMed1999

A prospective comparative study of MR sialography and conventional sialography of salivary duct disease.

OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of MR sialography in the examination of patients with salivary duct disease. SUBJECTS AND METHODS: Forty-nine patients (23 males and 26 females; 16-78 years old; mean age, 47 years) with symptoms related to the salivary glands underwent both conventional sialography and MR sialography. The latter was performed using a heavily T2-weighted, two dimensional, fast spin-echo technique and a 12-cm circular surface coil. Contiguous 3-mm axial images with frequency-selective fat suppression were acquired through the symptomatic gland. The MR sialography findings were compared with the final diagnoses determined by conventional sialography. RESULTS: Conventional sialography showed calculus disease (n = 13), stricture (n = 12), sialectasis (n = 4), cast (n = 3), neoplasm (n = 2), and normal duct (n = 16). MR sialography alone had a sensitivity of 69% in revealing calculus disease. However, the sensitivity increased to 100% when MR sialograms were combined with control radiographs. MR sialography was sufficient to accurately reveal stricture, sialectasis, and neoplasm and to direct therapy on the basis of its findings. Overall, MR sialography combined with control radiographs had a sensitivity, specificity, and diagnostic accuracy of 100%, 88%, and 96%, respectively, in revealing salivary duct abnormalities. CONCLUSION: MR sialography alone is not sufficiently sensitive to reveal salivary duct stones. Caution must be exercised when excluding calculus disease. MR sialography, when combined with control radiographs, is accurate and has the potential to replace conventional sialography.

Adolescent↗
PubMed1999

Role of MR cholangiopancreatography in patients with failed or inadequate ERCP.

OBJECTIVE: The purpose of our study was to evaluate the usefulness of MR cholangiopancreatography in the diagnosis and further treatment of patients with failed or inadequate ERCP. SUBJECTS AND METHODS: Fifty-eight patients with failed or inadequate ERCP underwent MR cholangiopancreatography using a two-dimensional heavily T2-weighted multislice fast spin-echo technique. The final diagnosis was made on the basis of a second ERCP (n = 4), percutaneous transhepatic cholangiopancreatography (n = 19), intraoperative cholangiography (n = 6), percutaneous biopsy (n = 3), surgical findings (n = 5), or clinical follow-up (n = 21) for a mean period of 22 months (range, 7-31 months). RESULTS: MR cholangiopancreatography was technically successful in 57 patients and resulted in a sensitivity, specificity, and diagnostic accuracy of 97.1%, 100%, and 98.2%, respectively. Overall, MR cholangiopancreatography gave clinically useful information that contributed to patient management in 56 (96.6%) of the 58 patients. On the basis of the MR cholangiopancreatography findings, patients were managed using a second ERCP (n = 4), combined percutaneous and endoscopic procedure (n = 2), percutaneous biliary stent insertion (n = 13), surgery (n = 12), chemotherapy (n = 1), or conservative treatment (n = 24). CONCLUSION: MR cholangiopancreatography was found to have a unique and valuable role in the investigation of patients in whom ERCP failed or was inadequate. MR cholangiopancreatography helped us avoid using invasive procedures such as percutaneous transhepatic cholangiography in the diagnosis of bile duct disease after failed ERCP.

Adolescent↗
PubMed1999

Cervical epidural lipoblastomatosis: changing MR appearance after chemotherapy.

Lipoblastomatosis is a locally infiltrative tumor of embryonic fat. We describe the MR appearance of cervical lipoblastomatosis with epidural extension. The initial MR study showed features of a soft-tissue mass; a subsequent MR examination, performed after chemotherapy, depicted the lesion as a typical lipoma of high signal intensity on T1-weighted images and of intermediate signal on T2-weighted sequences.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Histological parameters as predictors of prognosis in childhood brain tumors.

Using histological parameters with high recognition reliability, we retrospectively analyzed all newly diagnosed patients under the age of 16 years (n = 100) with brain and spinal cord tumors presenting to the National Neuroscience Centres of the Richmond and Beaumont Hospitals, Dublin, Ireland, between 1985 and 1990, allowing analysis of 5-year survival in all cases. Tumor histology was reviewed by two neuropathologists blinded to previous histological diagnosis and to the site of lesion. We found that certain histological features such as very low cell density and microcyst formation had a positive effect on prognosis. Mitoses and pleomorphism had a negative effect on prognosis, whereas necrosis and meningeal involvement had no effect on prognosis. It is suggested that identification of reliably recognized histological features rather than assignation of tumors to particular diagnostic categories may be a more reliable predictor of tumor behavior in the pediatric age-group.

Adolescent↗
PubMed1998

Pathogen-free granulomatous diseases of the central nervous system.

Pathogen-free granulomatous diseases (PFGD) of the central nervous system (CNS) are a group of disorders with protean clinical and pathological findings. Failure to identify a causative organism leads to considerable diagnostic difficulty. The neuropathology records between 1985 and 1995 were retrospectively reviewed, and the medical records of all patients in whom a diagnosis of PFGD of the CNS was made were retrieved. Patients in whom an infective agent was shown either by culture, special staining techniques, or by immunohistochemical methods were excluded. We identified 11 patients (eight male, three female) who fulfilled the pathological criteria for this condition. Average age at diagnosis was 38.7 years (range, 17 to 78). Neurological symptoms were the presenting feature in nine patients. Neuroimaging findings included hydrocephalus (54.5%), meningeal enhancement (45.5%), and mass lesions (45.5%). Seven patients had antemortem CNS biopsies (brain/meninges [n = 6], spinal [n = 1]), which showed noncaseating granulomas. Eight patients died (mortality rate: 72.7%). Postmortem examination showed granulomatous involvement of the leptomeninges and cerebral parenchyma in all cases with systemic involvement in 50%, chiefly in the form of noncaseating granulomas of the hilar nodes. Six patients fulfilled the clinical, radiological, and pathological diagnostic criteria for neurosarcoidosis. The remaining five patients had an unclassifiable pathogen-free granulomatous disease of the CNS. PFGD of the CNS are associated with a poor prognosis. Although neurosarcoidosis may account for some of the cases, there remains an unclassifiable subgroup that continues to be a diagnostic and management challenge.

Adolescent↗
PubMed1998

Merosin-deficient congenital muscular dystrophy and cortical dysplasia.

Congenital muscular dystrophy (CMD) encompasses a heterogenous group of muscle disorders with autosomal recessive inheritance, characterized by muscular weakness and hypotonia at birth or within the first few months of life and developmental delay. Merosin-deficient CMD is a clinically distinct form which may be associated with significant abnormalities of the brain detectable by neuroimaging. We report two siblings of consanguineous parents with merosin-deficient CMD in an Irish family who in addition to the characteristic white matter abnormalities on neuroimaging, had occipital dysplasia. Clinical, electrophysiological muscle biopsy findings and neuroimaging were very similar in both cases. Although merosin-deficient CMD with white matter abnormalities on neuroimaging is well documented in the literature, the association with occipital dysplasia has only rarely been reported. The appearance of an identical cortical defect in these siblings suggests an underlying genetic mechanism.

Biopsy↗
PubMed1998

Fatal pleomorphic xanthoastrocytoma with meningeal gliomatosis.

AIMS: To report the previously undescribed phenomenon of extensive meningeal gliomatosis in a pleomorphic xanthoastrocytoma (PXA) and to examine possible prognostic features. CASE DETAILS: An 11-year-old girl underwent excision of a left temporoparietal pleomorphic xanthoastrocytoma and 8 months later underwent re-excision of a local tumour recurrence. Although mitoses were not present in any of the resection specimens, the development of necrosis and increased immunoreactivity for proliferating cell nuclear antigen (PCNA) indicated anaplastic transformation in the recurrent tumour. Three months later extensive meningeal gliomatosis with minimal local recurrence resulted in death. CONCLUSIONS: Subarachnoid dissemination of a locally recurrent PXA in the absence of mitotic activity is an extremely unusual occurrence. PCNA expression in the initial excision specimens did not predict subsequent anaplastic transformation.

Astrocytoma↗
PubMed1998

Chronic active destructive herpes simplex encephalitis with recovery of viral DNA 12 years after disease onset.

Acute herpes simplex encephalitis (HSE) carries significant morbidity and mortality even after early treatment with antiviral agents (7). As well as causing acute neurological disease, Herpes viruses are associated with relapsing--remitting (Varicella--Zoster, Epstein-Barr) and chronic (Rasmussen encephalitis) disease processes (1). A two-year-old girl developed acute HSE which was followed by a 10-year neurologic illness characterised by asymmetric spastic tetraparesis, pseudobulbar palsy, the opercular syndrome of Foix-Chavany-Marie (4) and seizures. The neurological signs remained static until the child died suddenly 12 years after disease onset. Neuropathologic examination demonstrated active chronic encephalitis. Herpes simplex virus (HSV) DNA was recovered from formalin-fixed paraffin-embedded brain tissue. This case provides additional evidence for the development of chronic neurological disease attributable to persistence of herpes simplex virus type 1.

Brain↗
PubMed1998

Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages.

Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of Purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. Monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality.

Ataxia↗
PubMed1998

Immunohistochemical evaluation of merosin deficiency in congenital muscular dystrophies.

OBJECTIVES: To determine the prevalence of merosin deficiency in cases of unclassified congenital muscular dystrophy and to determine the temporal stability of merosin epitopes in fixed and stored archival material. MATERIALS AND METHODS: Using an antibody to human merosin we retrospectively studied 12 cases of undiagnosed muscular dystrophy from our files to determine the prevalence of merosin deficiency. Where fresh muscle was not available, unstained stored cryostat sections or destained archival stored sections were incubated with the merosin antibody. RESULTS: Two of the 12 cases of undiagnosed muscular dystrophy were merosin-deficient. No difference in intensity of merosin staining was found between freshly cut cryostat sections and unstained stored cryostat sections. There was no difference in the intensity of merosin staining in sections archived for up to 10 years. CONCLUSIONS: We conclude that 16% of unclassified muscular dystrophies in our study are due to merosin deficiency and that merosin antigenicity remains intact in archival stored muscle tissue, facilitating retrospective evaluation of patients in whom frozen muscle is not available. To our knowledge, this latter observation has not been reported previously.

Biopsy↗
PubMed1997

Paramyotonia congenita and hyperkalemic periodic paralysis associated with a Met 1592 Val substitution in the skeletal muscle sodium channel alpha subunit--a large kindred with a novel phenotype.

Paramyotonia congenita (PC) and Hyperkalemic periodic paralysis (HyperPP) are caused by amino acid substitutions in the alpha subunit of the human skeletal muscle sodium channel. One such substitution, methionine for valine at position 1592, has been associated with HyperPP with myotonia and cold sensitivity. We report clinical, electromyographic (EMG), genetic and pathological features of a large kindred with the Met1592Val substitution. Affected members were phenotypically heterogenous and had episodic potassium-sensitive paralysis, and stiffness and weakness induced by exercise and cold, which was confirmed by EMG studies. These features indicate a combined PC-HyperPP phenotype not previously described with this mutation.

Adult↗
PubMed1997

Acute near-fatal parainfectious cerebellar swelling with favourable outcome.

The clinical course, neuro-imaging features and neuropathologic findings in a child with para-infectious acute cerebellar swelling are described. Reversible transtentorial and transforaminal herniations occurred and required emergency posterior fossa decompression with external ventricular drainage. Neuropathologic examination of a cerebellar biopsy demonstrated a subacute pathogen-free cerebellitis. Following neurosurgical intervention and steroid therapy, symptoms and signs resolved and the patient is well 3 years later. Acute para-infectious cerebellar swelling is potentially fatal unless recognised and treated early in its evolution.

Cerebellar Diseases↗
PubMed1996

Deficiency of respiratory chain complex I is a common cause of Leigh disease.

We reviewed the clinical features and etiologies of Leigh disease in 66 patients from 60 pedigrees. Biochemical or molecular defects were identified in 50% of all pedigrees, and in 74% of the 19 pedigrees with pathologically proved Leigh disease. Isolated deficiency of respiratory chain complex I was found in 7 patients, though the complex was only assayed in 25 patients, making this the second most common biochemical abnormality after complex IV deficiency. Mutations at residue 8993 of mitochondrial DNA were found in only 2 patients. No correlation was found between the clinical features and etiologies. No defects were identified in the 8 patients with normal lactate concentrations in the cerebrospinal fluid.

Blotting, Southern↗
PubMed1996

Multifocal remitting-relapsing cerebral demyelination twenty years following allogeneic bone marrow transplantation.

We report a case study of a female who received an allogeneic bone marrow transplantation (BMT) from a sex-mismatched related donor and who, after a twenty-year interval, developed an acute fulminant biopsy-proven demyelinating disorder of cerebral white matter which followed a remitting-relapsing chronic course. In situ hybridization studies using Y-chromosome-specific markers revealed Y-chromosome-positive mononuclear cells in biopsy samples of white matter. Magnetic resonance imaging (MRI) studies of the asymptomatic healthy male donor showed multiple white matter lesions. These observations suggest that donor lymphocytes were sensitized to central nervous system (CNS) antigens prior to or at the time of transplantation but remained dormant for 20 years before becoming activated to cause widespread demyelination.

Adult↗