Biomedical subjects

Edward J Kendall

Publications and source records attributed to Edward J Kendall.

9 recordsLinked to original sources

PubMed2006

Nuclear magnetic resonance spectroscopy of bovine ovarian follicular fluid at four selected times of the oestrous cycle.

The objective of the study was to determine if nuclear magnetic resonance (NMR) spectral features of ovarian follicular fluid were correlated with the physiological status of follicles so that we could assess the feasibility of using NMR spectroscopy during assisted reproduction therapy. Thirty-five sexually mature, nullparious heifers were monitored by transrectal ultrasonography to assess their follicle wave status during the oestrous cycle. Ovariectomies were performed on Day 3 of wave 1 (D3W1, n = 10), Day 6 of wave 1 (D6W1, n = 9), Day 1 of wave 2 (D1W2, n = 9), or in the immediate preovulatory period of at least 17 days after ovulation (De17, n = 9). Follicle status was determined to be dominant or subordinate. Follicular fluid was extracted from the follicles and NMR spectra were collected. Principal components were extracted from ratios of line amplitudes and tested for effects of follicle status (dominant v. subordinate) and cycle time point (D1W3, D1W6, D1W2 and De17) using multivariate analysis of variance. For most line ratio combinations, main effects of status, time point and their interaction were found (P < 0.05). We concluded that NMR spectra may be used for the determination of ovarian follicle physiological status.

Acetates↗

PubMed2006

Automated search for arthritic patterns in infrared spectra of synovial fluid using adaptive wavelets and fuzzy C-means analysis.

Analysis of synovial fluid by infrared (IR) clinical chemistry requires expert interpretation and is susceptible to subjective error. The application of automated pattern recognition (APR) may enhance the utility of IR analysis. Here, we describe an APR method based on the fuzzy C-means cluster adaptive wavelet (FCMC-AW) algorithm, which consists of two parts: one is a FCMC using the features from an M-band feature extractor adopting the adaptive wavelet algorithm and the second is a Bayesian classifier using the membership matrix generated by the FCMC. A FCMC-cross-validated quadratic probability measure (FCMC-CVQPM) criterion is used under the assumption that the class probability density is equal to the value of the membership matrix. Therefore, both values of posterior probabilities and selection criterion MFQ can be obtained through the membership matrix. The distinctive advantage of this method is that it provides not only the 'hard' classification of a new pattern, but also the confidence of this classification, which is reflected by the membership matrix.

Algorithms↗

PubMed2005

Neuroprotection from soman-induced seizures in the rodent: evaluation with diffusion- and T2-weighted magnetic resonance imaging.

Exposure to the organophosphate nerve agent soman produces seizures that in turn lead to neuropathology. This study describes the temporal and spatial evolution of brain pathology following soman-induced convulsions and the attenuation of these alterations after neuroprotective intervention with magnetic resonance imaging (MRI). Neuroimaging 12 h after soman exposure, the hippocampus and thalamus exhibited significant decreases (23%) in apparent diffusion coefficients (ADC). These acute effects were resolved by 7 days. In addition, T2 measurements declined significantly at 12 h (37%) returning to near normal values by 24 h. Histopathological analyses confirmed moderate cell loss within the hippocampus and piriform cortex. Together these findings suggest that initial cell death was resolved through regional cellular remodeling. Pharmacological countermeasures were administered in the form of diazepam, a benzodiazepine anticonvulsant, or gacyclidine (GK-11), an anti-glutamatergic compound. Diazepam therapy applied immediately after soman exposure prevented acute ADC changes. However the presence of edema, using T2 measurements, was detected at 3 h within the retrosplenial, amygdala and piriform cortices and at 12 h in the thalamus (34% below normal). GK-11 therapy appeared to prevent most of these changes. However at 7 days after soman, a decrease (17%) in ADC was observed in the piriform cortex. Pathology was confined to the piriform cortex suggesting that this region is more difficult to protect. This is the first report that provides temporal and spatial resolution using MRI with histological correlation of pharmacological interventions against soman-mediated seizure-induced neuropathology.

Animals↗

PubMed2004

Magnetic resonance diffusion imaging of ovarian masses: a first experience with 12 cases.

OBJECTIVE: The objective of the study was to determine the feasibility of using apparent diffusion coefficient (ADC) measurement for the differential diagnosis of malignancy in ovarian masses. MATERIALS AND METHODS: Twelve cases involving ovarian masses were imaged using spin echo diffusion magnetic resonance imaging (MRI). Five cases involved malignant ovarian masses, on the basis of postoperative histologic examination, and the rest involved benign masses. The ovarian masses were imaged in vivo (10 cases) before surgery and ex vivo (8 cases) after surgical resection. Diffusion-weighted data were corrected for motion using the phase data from unweighted data in nine cases. Multifactorial analysis of variance was used to evaluate the effects of malignancy, location (in vivo versus ex vivo), and motion correction on the measurement of ADC intensity and texture. RESULTS: Motion correction caused an undesirable spatial smoothing of the ADC maps and a significant interaction (p=0.047) was found between location and motion correction. ADC value (p=0.028) and texture (p=0.001) differences were found between malignant and nonmalignant ovarian masses. CONCLUSION: Measurement of ADC intensity and texture has the potential to differentially diagnose malignancy in individual ovarian masses if the problem of image motion artifact can be eliminated through the use of faster imaging sequences.

Adult↗

PubMed2004

Neuronal and glial cell populations in the piriform cortex distinguished by using an approximation of q-space imaging after status epilepticus.

BACKGROUND AND PURPOSE: Temporal lobe epilepsy produces an injury cascade that includes neuronal loss and gliosis. The pilocarpine model reliably reproduces the symptoms of temporal lobe epilepsy and the resulting neuronal glial changes can be accurately depicted on diffusion-weighted images. The judicious choice of diffusion-encoding gradients can isolate multiple apparently isochromatic diffusing populations, but the assignment of these populations to specific tissue characteristics has been difficult. We sought to distinguish neuronal tissue from glial cell-infiltrated tissue by using signatures from unique spin populations obtained from an approximation of q-space imaging. METHODS: Ten male Sprague-Dawley rats received pilocarpine injections to induce seizures. All animals underwent diffusion-weighted imaging at 12 hours, 24 hours, and 7 days. At least two animals were selected for histologic analysis at each imaging time point. RESULTS: The results indicated that seizure-induced neurologic dysfunction may have been reflected in the emergence of new spin populations. In the piriform cortex-amygdala region of interest, the mean free diffusion path increased from 12 to 20 microm within 12 hours of seizure onset and persisted for at least 7 days. These results were temporally correlated with histologic evidence of necrotic changes. CONCLUSION: Our results suggest that even incomplete sampling of q space can provide useful physiologic information.

Amygdala↗

PubMed2003

Water self-diffusion tensor changes in an avian genetic developmental model of epilepsy.

Diffusion tensor imaging (DTI) was used to investigate whether tissue anisotropy in the developing brain is modified by recurrent seizures in epileptic chickens. Twelve epileptic chickens were sorted equally into two experimental groups at 10 days old. Until the age of 180 days, one group was photically stimulated beginning at an age of 2 weeks and repeated every 2 days while the other group was not stimulated. The photic stimulation induced generalized tonic-clonic seizures, and the unstimulated group did not display seizures. Both treatment groups were imaged at three time points, 45 (juvenile), 90 (adolescent), and 180 (adult) days posthatching, and maps of major and minor elements of anisotropy (eta and epsilon), trace and fractional anisotropy (FA) were generated. The eta, epsilon, and trace values in the hyperstriatum, archistriatum, and optic tectum showed significant changes as a function of developmental time point. Differences and/or interactions due to seizures were seen in the archistriatum and optic tectum for eta, epsilon, and trace with the largest differences between the stimulated and unstimulated birds being seen for eta in juvenile birds in the archistriatum (38.1 x 10(-11) m(2)/s versus 18.0 x 10(-11) m(2)/s) and the optic tectum (53.9 x 10(-11) m(2)/s versus 27.1 x 10(-11) m(2)/s). With the DTI parameters being sensitive to microstructure in the brain, these results demonstrate that seizures produce measurable differences, over unstimulated chickens, in brain structure for juvenile chickens, but the differences disappear as the brain matures. In other words, while seizure activity appears to induce atypical biophysical change (relative to unseizing birds) in the brain at a young age, the change is apparently reversed as the brain matures.

Adaptation, Physiological↗

PubMed2003

Recurrent nonstatus generalized seizures alter the developing chicken brain.

PURPOSE: Noninvasive magnetic resonance imaging was used to assess the evolution of seizure-induced pathology in epileptic, carrier, and normal chickens. Our objective was to determine whether repetitively evoked seizures in an epileptic fowl model of generalized seizures resulted in altered brain development. METHODS: Data were obtained from seizure and control groups at 45, 90, and 180 days after hatching. RESULTS: At 180 days, apparent diffusion coefficient (ADC) values in the optic tectum and archistriatum of the stimulated epileptic chicks were reduced, whereas ADC values in the nonstimulated group remained unchanged. The mean brain volume of epileptic chickens from the stimulated group was smaller than that from the nonstimulated group at 90 and 180 days. CONCLUSIONS: These findings establish that recurrent seizures modify the brain matrix.

Age Factors↗

PubMed2002

Evolution of beta-amyloid induced neuropathology: magnetic resonance imaging and anatomical comparisons in the rodent hippocampus.

Alzheimer's disease (AD) is characterized by the anatomical appearance of beta-amyloid (betaA) plaques and neurofibrillary tangles. These changes are also associated with cyclical inflammation, oxidative damage and, as inferred from the autopsied brains of patients, progressive injury to neurons. Here, we report the short-term effects of an intrahippocampal injection of the toxic betaA peptide fragment 25-35 in rats using quantitative magnetic resonance imaging (MRI) methods. Physiological changes within the cornu ammonis 1 (CA1) region of the hippocampus were monitored using a 1.5 T scanner at time points of 0.25, 1 and 24 h, and 7 and 14 days post injection. Spin echo T2-weighted (T2W) and diffusion weighted (DW) images were sequentially acquired. Apparent diffusion coefficients (ADC) were calculated and compared with histological alterations. A significant elevation in mean ADC values (17%) was observed in the ipsilateral CA1 at 14 days. The ADC changes were associated with disrupted pyramidal cells and nuclear lysis observed in histological sections. The contralateral CA1 exhibited a significant decrease in mean ADC of 15% at 14 days post treatment. Histological changes in the contralateral hippocampus suggested decreased neuronal density. T2W maps revealed no significant differences between the active betaA 25-35 fragment and its non-active analog, betaA 35-25. In conclusion, these results, based on changes in hippocampal ADC, demonstrate that the betaA 25-35 treatment induced pathology consistent with edema and cellular necrosis. This is the first report describing the evolution of AD-like pathology in an animal model using DW imaging.

Alzheimer Disease↗

PubMedDate not supplied

Reconsideration of pacemakers and MR imaging.

The presence of an implanted pacemaker is widely regarded as an absolute contraindication to magnetic resonance (MR) imaging; however, this viewpoint is based largely on safety concerns in the 1982-1996 period. Since 1996, changes in pacemaker electronics including decreased ferromagnetic content, increased sophistication of the circuitry, and onboard computer capabilities suggest that the absolute contraindication of MR imaging for pacemaker patients should be reconsidered. In addition, there are now data from prospective trials of 232 patients with demand pacemakers who underwent MR imaging at 0.5-1.5 T. Although a variety of pacemaker parameters were evaluated before, during, immediately after, and 3 months after MR imaging, no significant pacemaker changes were identified. No patients reported abnormal sensations such as pacemaker movement or irregular heartbeats even at direct questioning. These results suggest that peripheral locations such as the brain and knee may be considered for MR imaging. Thus, pacemaker patients should be assessed individually for their suitability for MR imaging, which may be performed safely under defined conditions.

Arrhythmias, Cardiac↗