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Biomedical subjects

R N Bryan

Publications and source records attributed to R N Bryan.

At least 109 records · Page 6Linked to original sources
PubMed1985

Improvements in the clinical utility of calculated T2 images of the human brain.

Magnetic Resonance Imaging (MRI) affords a considerable improvement in image contrast over other methods by virtue of the intrinsic NMR parameters spin density, T1, and T2. However, the clinical utility of routine quantification of these parameters is currently unknown. Calculated T2 images might afford additional disease specific information provided the calculation algorithm generates accurate T2 values. In this study, calculated T2 images of a MnCl2 phantom (spanning a T2 range of interest of 45.7 ms to 346.6 ms at 6 MHz) were generated utilizing a variety of calculation algorithms based upon a data set of 32 sequential spin-echo (SE) images. In general, when utilizing only the earliest sequential SE after the 90 degree pulse for the T2 calculation, the greater the number of SE used in the calculation algorithm, regardless of how they were averaged, the more accurate and less noisy was the calculated image. When only limited numbers of SE were used in the calculation algorithm, accuracy and noise varied with the choice of TE suggesting that there may be optimal timings for TE for a particular T2 range of interest. Forty-two calculated T2 head images of normal subjects, based upon data sets of 16 sequential SE, were evaluated for the T2 values of normal brain. These were compared to T2 images calculated via 7 different algorithms based upon 16 SE data sets from two patients with CNS pathology. An optimal algorithm was identified in which 16 SE Carr-Purcell-Meiboom-Gill (CPMG) were averaged into two images for the T2 calculation. With this algorithm, calculated images could be generated efficiently which were accurate and relatively noise free. The availability of such images maximized whatever disease specificity, and thus clinical utility, T2 information affords.

Brain↗
PubMed1984

Nuclear magnetic resonance diagnosis of an anaplastic astrocytoma.

A patient presented with an 8-month history of a progressive left homonymous visual field deficit, left hemiparesis, and a left thalamocortical sensory deficit that was not detectable by repeated conventional neurodiagnostic evaluations. Proton nuclear magnetic resonance (NMR) imaging revealed a right parietal lesion characterized by a prolonged T2 (spin-spin relaxation time). At surgery, the mass proved to be an anaplastic astrocytoma. NMR appears to be more sensitive than x-ray computerized tomography scanning in some patients with malignant gliomas and offers the clinician an additional probe with which to evaluate these patients.

Astrocytoma↗
PubMed1984

Effect of nuclear magnetic resonance on chromosomes of mouse bone marrow cells.

Three groups of six male Balb/c mice, subjected to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 K Gauss for one hour, were each compared to another group of ten unexposed mice with respect to chromatid and chromosomal aberrations. The exposed groups were sacrificed at two hours, 24 hours and 48 hours following NMR exposure respectively. Control mice were sacrificed 24 hours after sham-exposure. All groups had approximately 0.02 apparent aberrations per cell. These apparent aberrations were in the form of metacentric chromosomes, possibly resulting from a union of chromosomes at their centromeres or possibly simply chromosomes in association. The results are consistent with earlier in vitro findings that NMR exposure causes no adverse cytogenetic effects.

Animals↗
PubMed1984

CT of laryngeal tumors.

CT is the radiographic procedure of choice in evaluating laryngeal neoplasia. CT not only is easily tolerable and relatively noninvasive for the patient but also assesses deep and extralaryngeal pathology. It allows tumor staging and, therefore, treatment planning to be more intelligently performed.

Female↗
PubMed1983

Intraarterial cis-platinum chemotherapy for patients with primary and metastatic brain tumors.

A total of 49 patients were treated using intraarterial cis-platinum infusions at a dose of 100 mg/m2. The patients were separated into three groups. There were 13 patients with metastatic tumors, 10 with recurrent malignant gliomas, and 22 patients with high-grade gliomas who received intraarterial cis-platinum as part of an adjuvant program. In addition, four nongliomatous primary brain tumors were treated in this fashion. Cis-platinum was filtered immediately prior to intraarterial infusion using a 0.22-micron filter. Response to treatment was evaluated by follow-up CAT scans and neurologic examinations. There were three complete and eight partial responses in metastatic tumors, and eight partial responses in recurrent gliomas. The median survival was 19 weeks for patients with metastatic disease, and 16 weeks for patients with recurrent gliomas. Those high-grade glioma patients who received intraarterial cis-platinum as adjuvant chemotherapy along with CCNU and radiation therapy had a projected median survival of 91+ weeks. Toxicity from intraarterial cis-platinum following drug filtration was markedly reduced when compared with previous reports. Only five patients experiencing visual or central nervous system toxicity utilizing filtered cis-platinum and no radiographic or histopathologic evidence of central nervous system toxicity was observed. Bilateral deafness was observed following vertebral artery infusion in both patients treated in this manner and thus vertebral artery infusions should be avoided. Systemic toxicity was mild. Intracarotid infusion is a safe, well-tolerated delivery system for filtered cis-platinum with a high response rate for patients with both metastatic and primary malignant brain tumors.

Brain↗
PubMed1983

Nuclear magnetic resonance evaluation of stroke. A preliminary report.

Nine patients who had acute and subacute stroke were examined by nuclear magnetic resonance (NMR) using a 6-MHz Bruker Instruments proton scanner. A modified Carr-Purcell-Meiboom-Gill pulse sequence was used for signal detection. The resultant string of spin-echoes was Fourier transformed into projections that were subsequently back-projected to a series of spin-echo images. From these images, spin density and T2 were calculated for each pixel. The NMR scans revealed stroke in each of the patients, while CT demonstrated only eight of the lesions. T2 was prolonged in all of the ischemic regions and is the most sensitive NMR parameter in detecting stroke. These preliminary results suggest that NMR scanning of patients who have acute stroke may be clinically useful, and that the T2 component of the NMR signal is most important.

Cerebrovascular Disorders↗
PubMed1982

Intra-arterial cisplatin treatment of adenoid cystic carcinoma.

Adenoid cystic carcinoma (ACC) is unique among salivary gland tumors in both its natural history and in its response to nonsurgical treatment methods (ie, radiation and chemotherapy). The chemotherapeutic agent, cisplatin, seems to be unique in its ability to affect ACC. It might be that ACCs of the minor salivary glands are especially vulnerable to the intra-arterial method of administering this drug, because there are accessible feeding vessels to most locations in which these tumors occur. We have treated four patients with advanced ACC with intra-arterial cisplatin. The responses suggest that this method may be a useful adjunct in the management of this tumor both as a preoperative and as a palliative measure.

Aged↗
PubMed1982

Neurotoxicity of iohexol: a new nonionic contrast medium.

The neurotoxicity of iohexol was evaluated and compared with the neurotoxicity of sodium diatrizoate, meglumine iothalamate, and metrizamide. Direct neurotoxicity was evaluated with in vitro rat hippocampal slices, and angiographic neurotoxicity was studied in a cat's spinal cord following thoracic aortography. In the experiments with the hippocampal slices, the ionic agents, sodium diatrizoate and meglumine iothalamate, and metrizamide caused early excitatory changes in electrical activity and later inhibition, but iohexol caused only inhibition. In the experiments with the cat's spinal cord, the ionic contrast materials produced an increase in the ventral root reflexes, and iohexol and metrizamide produced no significant effect. These results indicate that iohexol is less neurotoxic than metrizamide and the ionic contrast materials and may be a very useful angiographic and/or myelographic contrast agent.

Animals↗
PubMed1982

Computed tomography of the major salivary glands.

Forty-eight patients with proven disease of the salivary glands were evaluated by computed tomography (CT). Twenty-seven patients had salivary gland neoplasm and all were identified by CT. Fifteen benign tumors appeared as discrete, sharply marginated, high-density masses embedded in an otherwise normal gland. All 15 were correctly identified as benign by CT. There were 12 malignant tumors; 10 were invasive and presented as poorly defined, relatively dense lesions which obliterated and/or transgressed adjacent fat and fascial planes. Two malignant tumors presented as discrete masses and were incorrectly considered to be benign by CT. Twenty-one patients with inflammatory disease of the salivary glands were studied. A variety of patterns were noted, the most common a relatively diffuse, irregular area of increased density in an enlarged gland. Salivary duct calculi, diffuse sialectasis, and enlarged lymph nodes were well demonstrated. Differentiation between focal and inflammatory disease and malignant neoplasm was difficult. Computed tomography may be augmented by coincident sialography, although it is seldom necessary.

Adolescent↗
PubMed1980

Role of hydration state and thiol-disulfide status in the control of thermal stability and protein synthesis in wheat embryo.

Reduced (GSH), oxidized (GSSG), and protein-bound (PSSG) glutathione were determined in dry and hydrated wheat embryos. Dry embryos contained about 0.6 mumoles per gram dry weight each of GSSG and PSSG, and these levels declined 5- to 10-fold within minutes after the onset of imbibition. GSH declined from about 8 to 2 mumoles per gram over a period of 90 minutes. Similar changes occurred when embryos were hydrated by storage at 100% relative humidity. The decline in glutathione levels was not reversed upon redrying hydrated embryos. About 40% of the cysteine residues of embryo protein was found to be in the disulfide form in both dry and imbibed embryos. The ability of wheat embryos to withstand heat shock was shown to correlate with water content but not GSSG content. Incorporation of [(35)S]methionine into protein was studied using a system based upon wheat embryo extract (S23). Incorporation rate was found to be sensitive to the nature of thiol added to the system and to be decreased by GSSG. S23 exhibited a substantial capacity to reduce GSSG and preparation of S23 having a GSSG content comparable to dry embryos required addition of large amounts of GSSG to the extraction buffer S23 prepared in this fashion exhibited a marked decrease in ability to support protein synthesis. These results suggest that the early decrease in GSSG during germination is necessary for optimal protein synthesis in wheat embryo.

Journal Article↗
PubMed1978

Premature craniosynostosis: A common complication of juvenile thyrotoxicosis.

Cranial vault suture opacification (apparent closure) and bone age were evaluated roentgenographically in ten children with thyrotoxicosis. The bone age was advanced greater than 2 SD in only one. In comparison to 96 control children of similar age, craniosynostosis was present in each of the patients with thyrotoxicosis. Children with advanced bone age, nine due to virilizing adrenal hyperplasia and three with precocious puberty, had normal radiographic patterns of cranial suture closure. Thyrotoxic premature craniosynostosis did not interfere with continued head circumference growth nor did it result in clinical or radiographic evidence of increased intracranial pressure. We conclude that premature craniosynostosis appears to be a common feature of juvenile thyrotoxicosis. Investigation of the possible long-term adverse effects of this entity on central nervous system function is advocated.

Adolescent↗
PubMed1978

Glossopharyngeal schwannomas.

Glossopharyngeal schwannomas are rare entities. Our recent experience with three such cases treated successfully, suggests that recognitton of this tumor as a discrete entity is both desirable and feasible. Although this tumor shares with the far more common acoustic schwannoma the presenting symptom of hearing loss, it may be distinguished by an elicitable history of hoarseness, demonstration of abnormal palatal function and absence of expected findings upons standard radiographic examination of the petrous bones and internal auditory canal. We have found that identification of this tumor may be accomplished with currently available diagnostic technics, including computerized tomography. The authors review the literature and report their experiences regarding preoperative assessment, operative technic and the postoperative course.

Adult↗