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Biomedical subjects

L Beach

Publications and source records attributed to L Beach.

12 recordsLinked to original sources
PubMed2001

Anomalous origin of 4 coronary ostia from the right sinus of Valsalva in a patient with hypertrophic cardiomyopathy.

Anomalous origin of 4 separate coronary ostia from a single coronary sinus has rarely been reported. We report what is to our knowledge a previously undescribed variation characterized by the left anterior descending, left ramus, left circumflex, and right coronary arteries originating from separate ostia in the right sinus of Valsalva. In addition, the autopsy disclosed features of hypertrophic cardiomyopathy, rarely associated with congenital coronary anomalies.

Cardiomyopathy, Hypertrophic↗
PubMed1997

A phase I trial of neutron brachytherapy for the treatment of malignant gliomas.

We performed a phase I trial to test the feasibility of neutron brachytherapy using californium-252 (252Cf) as the sole source of radiation, and to determine the maximum tolerable dose (MTD), for the treatment of malignant gliomas. Previous studies using external beam neutron radiation have shown that neutrons are capable of totally eradicating malignant gliomas. However, in most cases, fatal widespread radiation necrosis resulted. Radioactive implants are a logical method of increasing the dose to the tumour and decreasing the dose to normal brain. 252Cf is a relatively stable neutron-emitting isotope suitable for implant therapy. The study was an open ended dose-escalation study. All radiation was delivered by using only 252Cf implants, without external beam therapy of any type. The first dose step was 900 neutron cGy (ncGy); each subsequent step was increased by 100 ncGy. Three patients with newly diagnosed malignant gliomas were entered at each dose step, and the number was increased to six patients in dose steps at which necrosis of brain occurred. The study ended when two patients at any dose step developed radiation necrosis of brain outside the prescribed radiation field. 33 patients were entered into the study. 10 patients developed scalp necrosis associated with scalp doses above 900 ncGy. The study ended when two patients at the 1300 ncGy dose step developed radiation necrosis of brain. We conclude: (1) neutron brachytherapy using 252Cf as the sole source of radiation is a feasible treatment for malignant gliomas; (2) the scalp tolerates less neutron radiation than the brain; (3) the MTD (and the recommended dose for a phase II trial) of interstitial neutron brachytherapy is 1200 ncGy.

Adult↗
PubMed1993

A template for rigid stereotaxic afterloading brachytherapy of the brain.

PURPOSE: This paper describes a system for the implantation of rigid stainless steel afterloading tubes into the brain using a stereotaxic head frame for both localization and treatment. METHODS AND MATERIALS: The stereotaxic frame is attached to the skull throughout the treatment, and the afterloading tubes are both rigid and fixed to the frame. The source positions are therefore fixed relative to the skull throughout the irradiation. Design and construction of templates, afterloading tubes and clamps are discussed in detail. RESULTS: The rigidity of the resulting implant provides accurate and immobile positioning of the planned isodose distribution relative to the defined treatment volume and makes it possible to carefully and rapidly plan a source loading which will best cover the volume of interest. The source template is not in contact with the patient at any time. The afterloading tubes are held strictly parallel during treatment, allowing for rapid and versatile preplanning prior to surgical placement. Placement options are enhanced by using a set of rotating templates. CONCLUSION: This system has been used for over 60 procedures without any mechanical or safety problems and has provided a significant improvement in both the speed and confidence of localization and treatment planning. There are significant advantages of such a system for High Dose Rate Afterloading Brachytherapy.

Brachytherapy↗
PubMed1988

The Ds1 transposable element acts as an intron in the mutant allele Adh1-Fm335 and is spliced from the message.

The Ds-induced maize Adh1 allele Adh1-Fm335 retains its anaerobic regulation and normal transcription start site despite the presence of the 405 bp Ds element in the 5' untranslated leader region of the gene. The steady state level of Adh1-specific transcript is reduced to about 1% that of the progenitor or revertant alleles. Run-on transcription studies show that the reduced level of Adh1 specific mRNA is not attributable to a decreased transcription rate. S1 mapping indicates that the Ds element is spliced from the Adh1-Fm335 transcript using a donor site 14 bp into the Ds element and an acceptor site at the 3' junction of the Ds element with the flanking genome DNA.

Alcohol Dehydrogenase↗
PubMed1984

Intracerebral neutron brachytherapy for hemispheric glioblastoma multiforme. A pilot study.

The University of Kentucky Brain Tumor Study and Research Group has developed a new treatment protocol of interstitial brain brachytherapy using Californium-252 neutron source implantation in 1980. Only patients with malignant gliomas were eligible for this pilot study. Nine patients entered the Phase I trial of the protocol study between November 1980 and October 1981. According to the design of the protocol, all patients who had a verified histologic diagnosis of glioblastoma multiforme underwent postoperative intracerebral Cf-252 neutron source implantation, followed by 6 000 cGy of external photon beam irradiation. The purpose of this pilot study was to test the feasibility of interstitial Cf-252 neutron source implantation and only one implant afterloading applicator was used for brachytherapy. The implant applicator was placed in the center of tumor and the procedure was performed under CT guidance. In the assessment of the procedure, Karnofsky functional performance status, intellectual status, neurological examination, CT scans, and complications were used. All patients tolerated the procedure well and no serious complications were encountered. Despite the quality of these early treatments, there was some evidence of short-term benefit in duration of survival of the patients. We believe that further technical improvement to achieve an adequate isodose distribution to cover the tumor volume might result in longer duration improvement in survival.

Aged↗
PubMedDate not supplied

Reliability and validity of an algorithm for fuzzy tissue segmentation of MRI.

PURPOSE: A new multistep, volumetric-based tissue segmentation algorithm that results in fuzzy (or probabilistic) voxel description is described. This algorithm is designed to accurately segment gray matter, white matter, and CSF and can be applied to both single channel high resolution and multispectral (multiecho) MR images. METHOD: The reliability and validity of this method are evaluated by assessing (a) the stability of the algorithm across time, rater, and pulse sequence; (b) the accuracy of the method when applied to both real and synthetic image datasets; and (c) differences in specific tissue volumes between individuals with a specific genetic condition (fragile X syndrome) and normal control subjects. RESULTS: The algorithm was found to have high reliability, accuracy, and validity. The finding of increased caudate gray matter volume associated with the fragile X syndrome is replicated in this sample. CONCLUSION: Since this segmentation approach incorporates "fuzzy" or probabilistic methods, it has the potential to more accurately address partial volume effects, anatomical variation within "pure" tissue compartments, and more subtle changes in tissue volumes as a result of disease and treatment. The method is a component of software that is available in the public domain and has been implemented on an inexpensive personal computer thus offering an attractive and promising method for determining the status and progression of both normal development and pathology of the CNS.

Adolescent↗