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Biomedical subjects

J M Morris

Publications and source records attributed to J M Morris.

At least 37 records · Page 2Linked to original sources
PubMed1997

Noise reduction for NMR FID signals via Gabor expansion.

The parameters in a nuclear magnetic resonance (NMR) free induction decay (FID) signal contain information that is useful in biological and biomedical applications and research. A real time-sampled FID signal is well modeled as a finite mixture of modulated exponential sequences plus noise. We propose to use the generalized Gabor expansion for noise reduction, where the generalized Gabor expansion represents a signal in terms of a collection of time-shifted and frequency-modulated versions of a single sequence (prototype sequence). For FID signal-fitting, we choose the exponential sequence as the prototype function. Using the generalized Gabor expansion and exponential prototype sequences for FID model-fitting, an NMR FID signal can be well represented by the Gabor coefficients distributed in the joint time-frequency domain (JTFD). The Gabor coefficients reflect the weights of modulated exponential sequences in a signal. One of the important features is that the nonzero Gabor coefficients of a modulated exponential sequence will span a very small area in the JTFD, whereas the Gabor coefficients of the noise will not. If the exponent constant of the prototype sequence in the generalized Gabor expansion matches that of a modulated exponential sequence in the signal, then only one of the Gabor coefficients is nonzero in the JTFD. This is a very important property since it can be exploited to separate a signal from noise and to estimate modulated exponential sequence parameters.

Linear Models↗
PubMed1996

Neurologic disease attributable to infection with Parelaphostrongylus tenuis in blackbuck antelope.

Substantial mortality attributable to infection with Parelaphostrongylus tenuis was reported in 2 herds of blackbuck antelope (Antelope cervicapra) in southwestern Louisiana. Both herds had outbreaks in which all affected antelope had neurologic disease and subsequently died. Affected antelope were anorectic and weak. They staggered, trembled, isolated themselves from the herd, became recumbent, and, possibly, were blind. In 1 herd, 6 of 27 antelope were affected, and in the second herd, 7 antelope were affected. Both herds were on farms that raised various native and imported ruminants, including white-tailed deer. None of the remaining ruminants was affected during these outbreaks, and subsequent outbreaks have not been reported. Four antelope and the brain of a fifth antelope were submitted for postmortem examination. Meningeal worms were identified grossly in only 1 antelope. Metastrongyloid nematodes were detected histologically in 3 antelope. The amount and extent of inflammation varied greatly among affected antelope.

Animals↗
PubMed1996

A randomized controlled trial of aspirin in patients with abnormal uterine artery blood flow.

OBJECTIVE: To evaluate color Doppler imaging of the uterine arteries as a screening test in nulliparous women, and to examine the role of low-dose aspirin therapy in pregnancies with abnormal uteroplacental resistance. METHODS: At the routine 18-week fetal morphology ultrasound scan, 955 nulliparous women underwent color Doppler imaging of the uterine arteries. Abnormal uteroplacental vascular resistance was defined with respect to both the systolic-diastolic ratio of the flow velocity waveform and the presence of an ipsilateral early diastolic notch. Those with abnormal uterine artery waveforms were asked to participate in a randomized controlled trial of aspirin therapy. Pregnancy outcomes were compared in women with normal or abnormal flow velocity waveforms, as well as in the two arms of the intervention study. RESULTS: Of 186 women with abnormal uteroplacental resistance according to criteria defined previously, 102 agreed to randomization to either low-dose aspirin (100 mg/day) or placebo for the remainder of the pregnancy. Abnormal uterine artery flow velocity waveforms were associated with statistically significant increases in preeclampsia (11 versus 4%), birth weight below the tenth percentile (28 versus 11%), and adverse pregnancy outcome (45 versus 28%). Prophylactic aspirin therapy did not result in a significant reduction in pregnancy complications. CONCLUSION: Abnormal uteroplacental resistance at 18 weeks' gestation was associated with a significant increase in adverse pregnancy outcome. Low-dose aspirin did not reduce pregnancy complications in women with uteroplacental insufficiency.

Adult↗
PubMed1995

Tourniquet-induced hypertension in an ostrich.

Surgery was performed on a 3-year-old 110-kg male ostrich (Struthio camelus) to remove a sequestrum from the dorsal aspect of the left tarsometatarsal bone. A pneumatic tourniquet was positioned proximal to the surgical site and inflated to 600 mm of Hg. Systolic blood pressure increased 35% over 105 minutes while the tourniquet was inflated. Systolic blood pressure decreased 31.5% within 30 seconds after removal of the tourniquet pressure. Recovery from anesthesia and surgery was routine. The tourniquet-induced hypertension in this ostrich was similar to that reported for human beings and horses.

Animals↗
PubMed1995

Wilms' tumor 1 susceptibility (WT1) gene products are selectively expressed in malignant mesothelioma.

The distinction between malignant mesothelioma and other neoplastic processes involving the pleura is difficult, partly due to the lack of specific markers expressed on mesothelioma. Because of evidence suggesting that the Wilms' tumor susceptibility gene (WT1), unlike other tumor suppressor genes, is restricted mostly to mesenchymally derived tissues, we hypothesized that the WT1 gene products could serve as a potential marker for mesothelioma. The expression of WT1 mRNA was analyzed in 19 malignant mesothelioma cell lines and 9 tumors and compared with the expression of WT1 in 10 non-small cell lung cancer lines and 9 lung cancer specimens. WT1 mRNA was detectable by Northern analysis in 16 of 19 mesothelioma cell lines and in 5 of 8 malignant mesothelioma tumors. In contrast, WT1 mRNA was not detected by Northern analysis in non-small cell lung cancer lines or carcinomas. Immunoprecipitation with an anti-WT1 monoclonal antibody showed that a 52- to 54-kd protein was present in 4 mesothelioma cell lines. Immunostaining with this antibody localized the WT1 protein to the nucleus in two mesothelioma lines and in 20 of 21 mesothelioma tumors examined. This distinctive pattern of nuclear immunoreactivity was absent in 26 non-mesothelioma tumors involving the lung, including 20 non-small cell lung carcinomas. The detection of WT1 mRNA or protein may thus provide a specific molecular or immunohistochemical marker for differentiation of mesothelioma from other pleural tumors, in particular, adenocarcinoma.

Adult↗
PubMed1994

Evaluation of the new DrySlide beta-lactamase test.

Four hundred thirteen recent clinical isolates of Staphylococcus, Haemophilus, Moraxella, and Neisseria species were tested for beta-lactamase production using the Difco DrySlide beta-lactamase test. These results were compared with those of the BBL Cefinase reagent. Of the 413 isolates tested, 258 (62.5%) were beta-lactamase positive. There was 99.8% agreement between the two test methods; only one isolate of Staphylococcus aureus was DrySlide-negative and Cefinase-positive. The DrySlide beta-lactamase reagent is an accurate and convenient format for the evaluation of beta-lactamase activity in the clinical laboratory.

Evaluation Studies as Topic↗
PubMed1992

Sonographic evaluation of intrauterine growth retardation.

The prenatal recognition of the growth-retarded fetus is important because of the associated increased perinatal morbidity. Clinical methods of assessing fetal growth are disappointing and necessitate that a high-risk group be identified for more intensive surveillance. This review discusses the role of ultrasound biometry in establishing whether a fetus is small. Behavioral characteristics of the fetus may also be assessed using real-time ultrasound. The realization that not all small fetuses are a result of growth failure has led to the development of Doppler ultrasound to identify the fetus at risk. This paper focuses on the evidence supporting the selected use of Doppler ultrasound to investigate high-risk pregnancy.

Female↗
PubMed1991

Membranoproliferative glomerulonephritis in dogs with a genetically determined deficiency of the third component of complement.

Renal disease is a common clinical manifestation of genetically determined deficiencies of the complement system in man. Like their human counterparts, dogs with a genetically determined complete deficiency of C3 also develop renal disease. Five of 20 C3-deficient dogs developed clinical evidence of renal failure. However, 14 of the 15 remaining dogs had histological evidence of type I membranoproliferative glomerulonephritis. The lesions were characterized by mesangial cell proliferation, an increase in the mesangial matrix, thickening of the glomerular capillary wall, electron-dense deposits in the mesangium and subendothelial space, and the presence of IgG and IgM. In order to determine the effect of treatment with C3 on the renal disease of C3-deficient dogs, two C3-deficient dogs were infused with normal canine plasma twice weekly for 3 weeks. Their urinary protein excretion rose progressively from less than 200 mg/24 hr to greater than 1000 mg/24 hr; renal function remained normal. Renal biopsies performed 1 week after the last infusion revealed more severe glomerulonephritis and the presence of C3. As controls, a C3-deficient dog was given C3-deficient canine plasma and a normal dog was given normal canine plasma; neither control animal developed proteinuria or changes in their renal biopsy. These observations suggest that renal disease may be more common in humans with complement deficiencies than would be suspected based on clinical assessment. Furthermore, these results suggest that treatment with complement-containing blood products may worsen preexisting renal disease in complement-deficient individuals.

Animals↗
PubMed1991

Pancreatic adenocarcinoma with osseous metaplasia in a ferret.

A poorly differentiated pancreatic adenocarcinoma with regional lymphatic, hepatic, enteric and pulmonary metastases was diagnosed in an adult European ferret (Mustela putoris furo). The ferret showed clinical signs including a progressive, marked abdominal enlargement owing to ascites. Microscopic findings included intralesional osseous metaplasia. Exocrine pancreatic neoplasms in ferrets are rarely reported compared with neoplasms with endocrine differentiation.

Adenocarcinoma↗
PubMed1990

Lumbar spinal fusion. Assessment of functional stability with magnetic resonance imaging.

Segmental spinal instability was evaluated with magnetic resonance (MR) imaging, computed tomography (CT), and conventional radiography in 33 patients who had undergone surgical spinal fusion. In 16 of the 19 patients who had a diagnosis of solid fusion, the immobilized vertebral bodies demonstrated areas of high signal intensity on images with short repetition time (TR) and echo time (TE). The signal intensity of these areas was either less intense or normal on images with long TR and TE. In 10 of the 14 patients with segmental instability at the fusion site, subchondral vertebral bands of low signal intensity were shown on short TR/TE images, which demonstrated high signal intensity on long TR/TE images. All but two of the patients showed vertebral signal changes 12 or more months past fusion or onset of clinical symptoms. The vertebral MR signal intensity in solid lumbar fusions might be related to marrow composition changes resulting from decreased biomechanical stress, while the vertebral signal intensities in patients with unstable fusions might be related to reparative granulation tissue, inflammation, edema, and hyperemic changes. Magnetic resonance imaging appears to be unique in its assessment of functional fusion stability. Magnetic resonance may be most useful in patients symptomatic of fusion pseudarthrosis in whom conventional radiography and CT fail to demonstrate anatomic disruption.

Female↗
PubMed1989

Changes in neuronal size and neurotransmitter marker in hereditary canine spinal muscular atrophy.

Hereditary canine spinal muscular atrophy (HCSMA) is a dominantly inherited motor neuron disease that produces muscle weakness and atrophy. Immunocytochemical and computer-imaging morphometric methods were used to compare early changes that occurred in dogs with HCSMA (n = 4) versus controls (n = 2). The size and number of neurons in the ventral horn and the number of motor neurons expressing choline acetyltransferase were quantitated. The density of all ventral horn neurons per micrometer squared in dogs with HCSMA was greater than controls, and there were more small neurons than in controls. Immunocytochemical methods revealed more small cholinergic neurons and fewer large cholinergic neurons in HCSMA than in controls, suggesting growth arrest in HCSMA or a shift in size class from large cholinergic neurons to small ones. The density of cholinergic neurons per micrometer squared was not significantly different between the two groups. Analysis of predicted distributions of cholinergic and noncholinergic neurons revealed that HCSMA cholinergic neurons were smaller and that, in some size classes, fewer neurons expressed choline acetyltransferase. These observations indicate that in HCSMA the motor neuron fails to achieve normal size and/or undergoes atrophy.

Animals↗
PubMed1988

Role of C3 in humoral immunity. Defective antibody production in C3-deficient dogs.

Previous studies have shown that animals pharmacologically depleted of C3 have impaired antibody responses. However, such C depletion is neither complete nor sustained, and the C3 cleavage products generated by C3 depletion can both enhance and inhibit the immune response. To clarify the role of C3 in humoral immunity, the antibody response of dogs with genetically determined total deficiency of C3 (C3D) was examined. Serum IgG levels of the C3D animals were within the normal range, but were significantly lower than levels seen in normal controls or C3D heterozygotes. Specific antibody production was defective: the antibody titers of C3D dogs in response to primary intravenous immunization with two different T cell-dependent Ag (sheep E and bacteriophage phi X-174) were markedly reduced when compared to either normal controls or C3D heterozygotes. After secondary immunization with T-dependent Ag, the total antibody titers were normal, but the C3D dogs made proportionately more IgM and less IgG antibody than did either control group. After i.v. immunization with a T cell-independent Ag (DNP-Ficoll), the C3D dogs had reduced levels of IgM and IgG antibody after primary and secondary immunization. Neither i.m. immunization nor the use of a 20-fold increase in Ag dose i.v. could correct the defect seen in the antibody response of C3D dogs. The results herein demonstrate that C3 plays a critical role in the generation of a normal humoral immune response.

Agammaglobulinemia↗
PubMed1988

[3-dimensional computed tomography and multiplanar CT-reformations in lumbar spondylodesis].

Three-dimensional computed tomography (3-D-CT) and multiplanar CT reformations were performed in 42 patients who were clinically suspected of spinal instability following posterior lumbar fusion. Sagittal and coronal CT reformations demonstrated fusion pseudarthrosis more frequently than axial CT or conventional radiography. Three-dimensional CT cuts through the fusion revealed pseudarthrosis in most patients with positive 2-D images. In 5 patients, however, fusion appeared to be artifactually stable or unstable on 3-D cuts contrasting the 2-D images. Three-dimensional surface reconstructions demonstrated the complex anatomy of the fusion and showed superficial breaks. They were helpful in preoperative planning as well as intraoperative localization. 3-D-CT is a clinically useful adjunctive imaging method.

Adult↗