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Biomedical subjects

M Ross

Publications and source records attributed to M Ross.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

A multicenter clinical trial of Gadolite Oral Suspension as a contrast agent for MRI.

The purpose of this study was to assess the effectiveness and safety of Gadolite Oral Suspension as a gastrointestinal (GI) contrast agent for MRI in a phase II and two phase III multicenter clinical trials. Gadolite was administered to 306 patients with known or suspected abdominal and/or pelvic disease. MRI with T1- and T2-weighted sequences was performed before and after ingestion. Efficacy was evaluated by having two masked readers rate the certainty of their MR diagnosis (0 = uncertain, 1 = probable, 2 = definite) on randomly presented pre- and post-Gadolite Oral Suspension enhanced images. Principal investigators also evaluated the images and established the final diagnosis. Vital signs, clinical chemistries, and adverse events were documented. Blood and urine samples were analyzed for gadolinium content to determine whether Gadolite Oral Suspension was absorbed systemically. Certainty in MR diagnosis increased significantly (P < .001) for both blinded readers between pre- and post-Gadolite images (.49-1.18 for reader 1: .46-1.53 for reader 2). Sensitivity, specificity, and accuracy also increased for both masked readers. No gadolinium was detected in blood or urine samples. There were no serious adverse events and no apparent drug-related trends in mean vital signs or laboratory values. Gadolite is a highly effective, safe, and well tolerated contrast agent for clinical use with MRI.

Administration, Oral↗
PubMedDate not supplied

Presence of two subcomponents in P9 far-field potential following stimulation of the median nerve.

Close scrutiny of scalp recorded P9 far-field potentials following stimulation of the median nerve often revealed dilobed wave forms. We observed that the P9 became 2 distinct peaks (P9a and P9b) when the arm was flexed 90 degrees forward at the shoulder and that it became a pointed single peak with 90-170 degrees lateral abduction of the arm. A simultaneously recorded stationary negative peak (N9), registered over the stimulated arm with the use of a distant reference, also showed similar changes, a dilobed configuration (N9a and N9b) with forward flexion and a single peak with lateral abduction. The latencies of the scalp recorded P9a and P9b and arm recorded N9a and N9b were close but not exactly the same. Nevertheless, the latencies of the scalp-positive and arm-negative peaks shifted in nearly a parallel fashion by changing the arm positions. These findings suggest that the change of axial orientation of the propagating nerve impulse plays an important role for the rise of P9a and that the change of volume geometry surrounding the nerve contributes to the P9b generation. Also, the scalp recorded P9 and arm recorded N9 are one and the same, and oriented with dipole fields extending from the arm, body and to the scalp.

Action Potentials↗
PubMedDate not supplied

The influence of interfering input from the peroneal nerve on tibial-nerve somatosensory evoked potential.

Using a conditioning-test paradigm, we studied the recovery function of tibial nerve somatosensory evoked potentials (SEPs) conditioned by preceding peroneal nerve stimulation. The inter-stimulus intervals (ISIs) ranged from 0 to 400 msec, where 0 msec indicated simultaneous arrival of tibial and peroneal nerve volleys at the L1 spine. The recovery curve was W-shaped, showing two peaks of SEP suppression, maximum at 6 msec ISI (1st phase) and 50-75 ISI msec (2nd phase). In the 1st phase suppression, we found distinct differences in wave forms between 0-2 msec ISI and 4-6 msec ISI. At 0-2 msec ISI, P40-N50-P60 amplitude decreased and latencies shortened, while P31 and N35 were unchanged. At 4-6 msec ISI, all peaks, possibly excluding P31, were markedly depressed. We attribute the former change to an "occlusive effect" and the latter to an "inhibitory effect," each mediated via a central synaptic network between the two nerves. The attenuation of the 2nd but not the 1st phase suppression by peroneal nerve block distal to the stimulating electrodes provided evidence that the 2nd phase suppression resulted primarily from interfering afferent signals generated by peroneal nerve peripheral receptors, activated by foot movement.

Adult↗
PubMedDate not supplied

Deletion mapping on chromosome 10p and definition of a critical region for the second DiGeorge syndrome locus (DGS2).

DiGeorge syndrome (DGS) is a developmental field defect, characterised by absent/hypoplastic thymus and parathyroid, and conotruncal heart defects, with haploinsufficiency loci at 22q (DGS1) and 10p (DGS2). We performed fluorescence in situ hybridisations (FISH) and polymerase chain reaction (PCR) analyses in 12 patients with 10p deletions, nine of them with features of DGS, and in a familial translocation 10p;14q associated with midline defects. The critical DGS2 region is defined by two DGS patients, and maps within a 1 cM interval including D10S547 and D10S585. The other seven DGS patients are hemizygous for both loci. The breakpoint of the reciprocal translocation 10p;14q maps at a distance of at least 12 cM distal to the critical DGS2 region. Interstitial and terminal deletions described are in the range of 10-50 cM and enable the tentative mapping of loci for ptosis and hearing loss, features which are not part of the DGS clinical spectrum.

Cell Line, Transformed↗
PubMedDate not supplied

UHX1 and PCTK1: precise characterisation and localisation within a gene-rich region in Xp11.23 and evaluation as candidate genes for retinal diseases mapped to Xp21.1-p11.2.

The gene for ubiquitin hydrolase on the X chromosome (UHX1), cloned and mapped to Xp21.2-p11.2, is a candidate gene for retinal diseases. We used fine mapping techniques to localise UHX1 between markers DXS1266 and DXS337, where congenital stationary night blindness (XICSNB) and retinitis pigmentosa type 2 (RP2) are also located. Reevaluation of the UHX1 gene structure demonstrated five new exons, for a total of 21 exons and a predicted protein product of 963 amino acids. Evaluation of patients revealed no UHX1 mutations using SSCP (10 CSNB1 and 20 XLRP) or deletion screening with cDNA hybridisation (13 CSNB1 and 43 XLRP). Likewise, no aberrations were found in the nearby PCTAIRE1 (PCTK1) gene in 13 CSNB1 and 43 XLRP patients by deletion screening. Thus mutations of UHX1, and probably PCTK1, do not appear to cause common X-linked eye diseases. UHX1's role in patients with mental retardation may be appropriate for further investigations into UHX1 function.

Base Sequence↗
PubMedDate not supplied

Vulvar melanoma at the M. D. Anderson Cancer Center: 25 years later.

The purpose of this study was to review the clinical course of patients diagnosed with vulvar melanoma. Charts of patients diagnosed between 1970 and 1997 were reviewed for demographics, lesion characteristics, disease duration and extent, and treatments. Actuarial survival curves were computed by the Kaplan Meier method and compared by Cox proportional hazards regressions. Fifty-one patients (median age 54) with vulvar melanoma presented with a vulvar mass (39%), pain (30%), bleeding (24%), and itching (20%). Anatomical distribution was mucosa of the vulva (65%), vulvar epidermal site (21%), or unspecified vulva (14%), with 20% having multifocal disease at diagnosis. Histologic types were superficial spreading or nodular (50% each). Median lesion characteristics were diameter 2 cm, Breslow index 4.4 mm, and Clark level IV. Distribution of patients per American Joint Committee on Cancer (AJCC) stage was 29%, 50%, 16%, and 7% for stages I, II, III and IV, respectively. Inguinal node metastases were unilateral in 16% and bilateral in 7%. Despite complete surgical resection, 32 patients (63%) recurred. Median survival for all patients was 41 months (range, 5-324), with 91% 5-year survival for patients with stage I and 31% for stage >or= IIA (P = 0.0002). As with cutaneous melanoma, the AJCC classification, Breslow's thickness, and Clark's levels are the major predictors of overall survival (P = 0.0001 each) and disease-free survival (P <or= 0.0001, 0.0004, and 0.0002, respectively). Surgical techniques do not seem to alter the prognosis. Because vulvar melanoma carries a poor prognosis at early stages, the use of adjuvant therapies needs to be studied prospectively in women affected with this disease.

Adult↗
PubMedDate not supplied

Use of cosmid-derived and chromosome-specific canine microsatellites.

The majority of microsatellite markers being used to generate the emerging genetic linkage maps of the dog are derived from small-insert, random clones. While such markers are easy to generate, they have the disadvantage that they cannot easily be physically mapped by fluorescence in situ hybridization (FISH), making it difficult to assess the extent of genome coverage represented by such maps. In contrast, microsatellite markers from large-insert libraries enable the linkage groups within which they fall to be physically anchored to specific chromosomes. One aim of our work is to identify at least one microsatellite-containing cosmid clone for each canine chromosome, to ensure that linkage groups exist for all chromosomes. This is particularly important for a species with as complex a karyotype as the dog. Locating two cosmids on each chromosome would allow the orientation of the linkage groups to be established. Chromosomal locations of cosmid clones containing microsatellites have been determined by FISH and confirmed using canine chromosome-specific paints. Microsatellite sequences have been genotyped on the DogMap reference family. Microsatellites derived from flow-sorted, chromosome-specific libraries represent another source of useful markers. Initial studies have been carried out on the canine X chromosome, on which markers were underrepresented in our initial studies.

Animals↗
PubMedDate not supplied

Selecting amplification characteristics for young hearing-impaired children.

The task of selecting the electroacoustic characteristics of hearing aids for young hearing-impaired children continues to challenge many clinical audiologists. The rationale for a theoretically based approach to this problem is presented. Additionally, issues related to the choice of an idealized speech spectrum for a theoretical selection model are considered in relation to the acoustic environment and auditory needs of young hearing-impaired children. Finally, the preliminary version of a computer assisted speech spectrum approach, which facilitates the initial selection of frequency/gain and frequency/SSPL characteristics is presented.

Child, Preschool↗
PubMedDate not supplied

Comparative chemopreventive activity of ibuprofen and N-(4-hydroxyphenyl) retinamide against the development and growth of rat mammary adenocarcinomas.

The chemopreventive effects of Ibuprofen on the development and growth of 7,12-dimethylbenz(a)anthracene (DMBA) induced rat mammary tumors were examined. A well known breast cancer chemopreventive retinoid, N-(4-hydroxyphenyl) retinamide (4-HPR) was also included in this study for comparison. At 7 days prior to receiving a single intragastric dose of 15 mg DMBA, rats were fed a control chow diet, as well as diets containing either 1000 mg/kg diet of Ibuprofen or 1.5 mmol/kg diet of 4-HPR. Ibuprofen and 4-HPR markedly increased tumor latency. At 112 days post DMBA intubation, tumor incidence was 86% in control rats as compared to 74% and 62% in rats receiving Ibuprofen, and 4-HPR diets respectively (p < 0.05). Ibuprofen and 4-HPR reduced tumor burden and tumor volume almost to the same extent. The control rats had an average of 2.26 tumors/rat compared to 1.42 and 1.46 tumors/rat in the Ibuprofen or 4-HPR groups respectively (p < 0.05). Similarly, average tumor volume was 3.25 cm3 in the control rats compared to 0.86 cm3 and 0.83 cm3 in rats receiving Ibuprofen and 4-HPR diets respectively (p < 0.05). These results suggest that Ibuprofen may have potential in the chemoprevention and treatment of breast cancer.

Adenocarcinoma↗
PubMedDate not supplied

Gd-DTPA enhancement of the cisternal portion of the oculomotor nerve on MR imaging.

PURPOSE: To describe a radiographic finding--enhancement of the cisternal portion of the third cranial nerve on postcontrast MR--and to correlate it with patients' clinical symptoms and ultimate diagnosis. MATERIALS AND METHODS: Thirteen consecutive patients with enhancement of the cisternal portion of the third cranial nerve on postcontrast MR were retrospectively identified; 50 control patients referred for pituitary microadenomas were also retrospectively reviewed. FINDINGS: The enhancement was bilateral in six patients and unilateral in seven patients. Four of the six patients with bilateral enhancement had unilateral oculomotor nerve palsies; none had bilateral third cranial nerve palsy. Five of the seven patients with unilateral enhancement had ipsilateral third nerve palsies. Of the nine patients with third nerve palsies, the pupil was involved in four patients. Follow-up studies were available in six patients, four of whom had third nerve palsy. Resolution of the enhancement correlated with resolution of the symptoms in two patients. The patients' underlying diagnoses were lymphoma (four), leukemia (one), viral meningitis (one), neurofibromatosis (two), inflammatory polyneuropathy-HIV related (one), ophthalmoplegic migraine (one), Tolosa-Hunt syndrome (one), coccidioidomycosis (one), and diabetes (one). No enhancement was seen in any of the controls. CONCLUSION: Enhancement of the cisternal segment of the third cranial nerve is always abnormal, revealing an underlying inflammatory or neoplastic process. However, it is not always associated with clinically apparent oculomotor nerve dysfunction.

Adult↗
PubMedDate not supplied

Cytotoxic activity of di-n-butyltin(IV)(X-A-B-Y) compounds related to salicylic acid against human tumour cells.

A series of di-n-butyltin(IV) compounds of the type di-n-butyltin(IV)(X-A-B-Y) with the (X-A-B-Y) being related to salicylic acid was tested in vitro for cytotoxic activity against tumour cells of the human A 204, MCF-7, T24, WiDr and IgR-37 cell lines using the PIT method. In each cell line the di-n-butyltin(IV) compounds displayed similar activity. As compared to cisplatin, the compounds were 4- to 10-fold more effective against A 204, MCF-7 and T24 tumour cells and slightly more effective against WiDr cells. The effectiveness against IgR-37 cells was similar for cisplatin and di-n-butyltin (IV) compounds.

Cell Survival↗
PubMedDate not supplied

Pharmacokinetics of lopamidol after intrathecal administration in humans.

The kinetics of iopamidol, a new nonionic radiocontrast agent, were evaluated in 10 patients undergoing lumbar myelography. The doses of iopamidol administered intrathecally were 11 and 15 ml of a 200-mg iodine per ml solution in one and nine patients, respectively. Radiographs were made within 30 to 40 min and CTs were taken at about 1, 6, and 23 hr after iopamidol administration. The diagnostic quality and usefulness of the conventional and CT myelograms were considered excellent. In the lumbosacral subarachnoid space, the densitometry CT readings were maximal at 1 hr, whereas in the cervical subarachnoid space, peak CT values were reached at 6 hr. Plasma and urine samples were taken at frequent intervals up to 48 hr after the contrast agent was administered. Peak plasma levels of iopamidol were observed at 2.9 hr and were no longer detectable at 48 hr. The 48-hr urinary recovery for all patients averaged 66 +/- 8% of the dose. In all but one patient, iopamidol was cleared almost completely from the CSF within 24 hr. Side effects after iopamidol administration were transient and minor, and were not related to the CT readings or its systemic clearance.

Adult↗