Biomedical subjects

M K Edwards

Publications and source records attributed to M K Edwards.

At least 19 recordsLinked to original sources

PubMed1995

Girl with signs of Pelizaeus-Merzbacher disease heterozygous for a mutation in exon 2 of the proteolipid protein gene.

We studied a female infant with clinical signs of Pelizaeus-Merzbacher disease (PMD), who has a familial mutation (C41-->T) in exon 2 of the proteolipid protein gene (PLP), and selected relatives. While the carrier mother and grandmother of the proposita currently are neurologically normal and show normal T2 magnetic resonance imaging (MRI) of the brain, the infant has a neurological picture, MRIs, and brain auditory evoked response (BAER) consistent with that diagnosis. The data here presented show that PMD can occur in females carrying a mutation in the PLP gene. Our experience with the MRIs of this patient, her mother and grandmother, and those of a previously reported family [Pratt et al.: Am J Med Genet 38:136-139, 1991] show that molecular genetic analysis and not MRI is the appropriate means for carrier detection.

Brain↗

PubMed1994

Caenorhabditis elegans sqt-3 mutants have mutations in the col-1 collagen gene.

sqt-3 mutants of Caenorhabditis elegans form dumpy larvae and adults and display allele-specific defects in locomotion, fertility, and viability. We have determined that the sqt-3 locus encodes COL-1 collagen. We physically mapped the col-1 gene to a cosmid on chromosome V whose position is consistent with the location of the sqt-3 gene. We also observed morphological defects in sqt-3 mutants at stages that correlate with the mRNA expression patterns of col-1. Sequence analysis of the col-1 gene in the three temperature-sensitive mutants revealed that each allele of sqt-3 has a unique missense mutation causing arginine or glutamic acid to replace glycine in a Gly-X-Y triple helical domain. These glycine substitutions may result in longer non-collagenous domains, which may decrease the thermal stability or impart additional flexibility to mutant trimers. In addition, we describe four corrections to the published sequence of col-1, including one fifteen nucleotide addition that completes a conserved domain in the amino terminal coding region.

Alleles↗

PubMed1994

MRI in acute disseminated encephalomyelitis.

A retrospective analysis of CT and MRI studies in 12 patients with a clinical diagnosis of acute disseminated encephalomyelitis (ADEM) was performed. MRI was the definitive modality for the assessment of the lesions of ADEM: all patients had abnormalities consistent with the clinical diagnosis. Ten had abnormalities in the brain, three spinal cord lesions, and three showed evidence of optic neuritis. CT was normal in 6 of the 7 patients in which it was performed.

Acute Disease↗

PubMed1994

Langerhans cell histiocytosis of bone: MR imaging.

Magnetic resonance (MR) images of 12 pathologically proven lesions of Langerhans cell histiocytosis (LCH) of bone were reviewed retrospectively. MR identified all lesions, three of which were not identified on plain radiographs. In all cases, MR showed greater abnormality than did plain radiographs. With one exception, all lesions were hypointense on T1-weighted images and hyperintense on T2-weighted images. The lesions and associated soft tissue abnormalities were very conspicuous on short TI inversion sequences and T1-weighted post-contrast images. Follow-up MR studies in two patients after chemotherapy showed decreased size and enhancement of lesions compared with baseline studies.

Adolescent↗

PubMed1993

Magnetic resonance imaging of the head and neck.

MR imaging of the head and neck region has become the modality of choice for evaluating both malignant and benign tumors, functional derangements such as in temporomandibular joint dysfunction, and many congenital lesions. With improved scanner design and with newer pulse sequences becoming available, one can expect increased use of MR imaging in the future.

Disease↗

PubMed1993

Metabolic and degenerative diseases of childhood.

The metabolic and degenerative diseases of childhood are a diverse group of disorders with varied imaging features. Some of the disease processes have characteristic findings and some have no findings at all, but most present with nonspecific abnormalities in white matter. These patchy lesions, seen best on magnetic resonance scanning with T2 weighting, require a good history and a dialogue with the referring physicians to help in narrowing the differential possibilities. The major disease processes involving white matter are the dysmyelinating diseases, in which the abnormal white matter is the result of an inherited enzyme deficiency, and the demyelinating diseases, in which an acquired process such as infection destroys white matter. Several diseases result in gray matter abnormalities, including central pontine myelinolysis, MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like symptoms), Batten's disease, Leigh disease, and Wilson's disease.

Adolescent↗

PubMed1992

Imaging of metabolic diseases of the brain.

Increasing interest in metabolic diseases of the brain has revealed more specific patterns of disease, permitting us to make more accurate diagnoses or to suggest a more limited differential list of considerations. MR imaging is also useful in monitoring the course of the disease in processes for which treatment is available.

Brain↗

PubMed1991

Assessment and prevention of osteoporosis through use of a client self-reporting tool.

Osteoporosis is an age-related process that affects one out of every four women above 65 years of age. This article focuses on the assessment of osteoporosis through use of an osteoporosis assessment tool that is filled out by the client. The tool requests information about the woman's demographic profile, chief complaint, related symptoms, pain profile, risk profile, past medical history, nutritional history, fitness profile, menopausal history and self-care practices. The tool also includes information for the health care provider to complete about the client's lab analysis. Assessment needs to be extensive in order to uncover the specific factors that place an individual at risk for the silent changes of osteoporosis. The health care provider can elicit the aid of the client in securing such a comprehensive assessment.

Adult↗

PubMed1991

The role of MRI in cerebral infarction.

Although nuclear magnetic resonance has existed since the 1940s and was used extensively in chemistry labs for molecular structural determination, it was not until the 1970s that the possibility for magnetic resonance imaging (MRI) was realized. It is only in the last few years that the great potential of MRI to visualize the brain, joints and several other structures has been recognized. This article discusses some basic pathophysiology of cerebral ischemia as it relates to MRI and focuses on some of the advantages and disadvantages of MRI in visualizing and studying many of the resulting lesions.

Brain↗

PubMed1991

Imaging of metabolic diseases of the brain.

Awareness is increasing regarding the utility of MR imaging in the diagnosis and characterization of a wide number of inherited and acquired metabolic diseases. Although the pattern of disease is not often specific, the distribution may suggest a differential diagnosis that may be pursued by increasingly specific enzyme analysis. An exciting potential exists for detecting asymptomatic carriers for these diseases. MR imaging is also of value in monitoring these diseases and in planning therapy for those few conditions for which intervention is possible.

Adolescent↗

PubMed1990

Unilateral duplication of the cerebellar hemisphere and internal, middle, and external ear: a clinical case study.

This article presents the unique congenital anomaly complex of ipsilateral cerebellar hemisphere duplication and internal, middle, and external ear duplication. Diagnostic techniques included a head CT scan, a three-dimensional head CT scan, and a head MRI. An aberrant notochordal split was proposed as the embryologic mechanism leading to the development of such anomalies.

Abnormalities, Multiple↗

PubMed1990

Foci of increased T2 signal intensity in MR images of healthy elderly subjects. A follow-up study.

An 18-month follow-up study was conducted on 26 healthy elderly subjects with and without foci of increased T2 signal intensity on MR imaging. The subjects did not differ with respect to health status or cognitive performance as measured by the Cognitive Subscale of the Cambridge Mental Disorders of the Elderly Examination and the Mini Mental State Examination at follow-up. There was a significant decline in performance on the Digit Symbol Substitution Test in subjects who had evidence of T2 foci compared to the performance of subjects without T2 foci. This may indicate that the presence of T2 foci is correlated with subtle difficulties in learning and memory.

Aged↗

PubMed1990

Neuroimaging of disseminated germ cell neoplasms.

The purpose of this study was to determine the role of neuroimaging in the management of patients with metastatic germ cell tumors. Retrospective evaluation of 299 patients treated in 1986 and 1987 for initial presentation or recurrence of testicular, retroperitoneal, and mediastinal germ cell tumors was performed to determine indications for neuroimaging, frequency and site of CNS metastases, and occurrence of other CNS abnormalities. Sixty-six patients required CNS imaging with myelography, CT, or MR. Studies were normal in 24 patients. Twenty patients had CNS metastases including 11 with intracranial metastases, eight with spine lesions, and one with both brain and spine involvement. Sixteen had cerebral or cerebellar atrophy of unclear origin and functional significance. Two patients had ventriculomegaly without symptoms of hydrocephalus. Four patients had questionable lesions that were never confirmed. None of the 25 asymptomatic patients with elevated serum tumor markers had brain metastases. Fifteen of 17 patients with focal neurologic deficits and three of six patients with seizures had CNS metastases. CNS imaging to detect germ cell tumor metastases is most useful in the presence of neurologic deficits or seizures but is not useful in patients with unexplained elevation of serum tumor markers in the absence of neurologic deficits.

Adolescent↗

PubMed1990

Antigenic and dynamic properties of the surface of Onchocerca microfilariae.

We analyzed the antigenicity and stability of the surface of skin microfilariae (mf) of Onchocerca cervicalis, a horse parasite. These mf express antigens on their surface that are cross-reactive with the cattle parasite O. lienalis and with the human parasite O. volvulus. The surface of living O. cervicalis mf was radioiodinated using Iodogen and the labeled components were solubilized in buffers containing sodium dodecyl sulphate (SDS), or extracted with the milder detergent octyl-beta-D-glucopyranoside (OGP). Electrophoresis of this material showed seven prominent bands, one of which (14 kDa) was specifically precipitated by antisera from rabbits immunized with mf from either O. cervicalis, O. lienalis, or O. volvulus, and by human sera obtained from infected individuals in Chiapas, Mexico. Other components were precipitated by either the rabbit or the human sera. In addition, antisera from mice immunized with O. cervicalis mf bound specifically to the surface of freeze-thawed uterine O. lienalis and O. volvulus mf as detected by immunofluorescence. This fluorescence was lost from the surface of O. cervicalis mf in a temperature-dependent fashion. Live mf incubated on ice with mouse anti-mf antisera and secondary FITC-GAM, showed uniform surface fluorescence. When these mf were incubated at 37 degrees C, but not at 0 degrees C, the fluorescent pattern changed with time. First, small non-fluorescent patches arose, followed by an increasingly wide belt devoid of fluorescence, and finally, no visible fluorescence. These changes in the mf surface suggest potential mechanisms for immune evasion by filarial parasites.

Animals↗

PubMed1989

Brain-stem auditory evoked potential abnormalities with unilateral brain-stem lesions demonstrated by magnetic resonance imaging.

We correlated the brain-stem auditory evoked potential (BAEP) abnormalities in 24 patients with discrete unilateral brain-stem lesions demonstrated by magnetic resonance imaging. In 18 patients who had BAEP abnormalities either confined to or more severe on stimulation of one ear, the lesion on magnetic resonance imaging was in the brain stem ipsilateral to the corresponding ear. Mesencephalic lesions produced amplitude abnormalities of the IV/V complex while pontine lesions resulted in abnormalities of earlier components (wave II and/or III). Prolongation of the I-III interpeak latency tended to occur with pontine lesions and of the III-V interpeak latency with mesencephalic lesions. Unilateral brain-stem lesions, particularly at the mesencephalic level, often produced BAEP abnormalities on both ipsilateral and contralateral monaural stimulation.

Adult↗

PubMed1989

Dyke award. Gd-DTPA-enhanced MR imaging of experimental bacterial meningitis: evaluation and comparison with CT.

Gd-DTPA-enhanced MR images of experimental bacterial meningitis were obtained after Staphylococcus aureus was inoculated directly into the cisterna magna of four dogs. Each animal was studied with both unenhanced and enhanced MR and CT with Gd-DTPA and meglumine iothalamate, respectively. The enhancement patterns resulting from these techniques were compared and images were correlated with histopathology. All animals demonstrated abnormal leptomeningeal enhancement on MR with Gd-DTPA, but only one of four dogs exhibited abnormal contrast enhancement on CT. In these animals Gd-DTPA-enhanced MR also identified complications of meningitis, such as ventriculitis and cerebritis, more effectively than CT did. Unenhanced MR was not helpful in identifying meningitis. Histologic evaluation demonstrated that the abnormal areas of contrast enhancement on MR and CT correlated with inflammatory cell infiltration. However, some regions of mild leptomeningitis, ependymitis, and cerebritis identified histologically did not demonstrate abnormal enhancement. Since the animal model used was clinically and pathologically similar to human meningitis, we propose that Gd-DTPA-enhanced MR will subsequently be found more effective than unenhanced MR and IV contrast-enhanced CT for demonstrating meningitis and its complications in humans.

Animals↗

PubMed1989

White matter diseases.

White matter disease is imaged with great sensitivity and poor specificity on MRI. Congenital, vascular, infectious, and autoimmune diseases as well as those with many other causes, may create similar-appearing lesions on MR. A knowledge of disease patterns and pulse sequences may improve the diagnostic specificity, but there is no substitute for an adequate clinical history.

Brain Diseases↗

PubMed1988

HIPDM-SPECT in patients with medically intractable complex partial seizures. Ictal study.

Both interictal and ictal N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3,propanediamine -single photon emission computed tomography (HIPDM-SPECT) were performed in 16 patients with medically intractable complex partial seizures. Ictal HIPDM-SPECT localized epileptic foci in 13 of 14 patients with unilateral temporal focus and provided confirmative evidence of epileptic focus in 11 patients by demonstrating maximally increased regional cerebral perfusion (rCP) in epileptic foci that had shown decreased rCP in a previous interictal study. Ictal HIPDM-SPECT in two patients with bitemporal foci showed more complicated patterns consisting of slightly increased rCP in bilateral multifocal regions. Ictal HIPDM-SPECT was particularly useful for investigating epileptic foci, and correlation with simultaneously recorded ictal electroencephalograms provided further insight for localizing epileptic foci.

Brain↗