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Biomedical subjects

T Brady

Publications and source records attributed to T Brady.

At least 37 records · Page 2Linked to original sources
PubMed1987

Functional and scintigraphic evaluation of the silent adrenal mass.

Seven patients with unilateral and one patient with bilateral and asymmetric (R greater than L) incidentally discovered adrenal mass abnormalities depicted by computed tomography (CT) were studied by 131I-6 beta-iodomethyl-19-norcholesterol (NP-59) scintigraphy. There was marked lateralization of NP-59 uptake to the side of the mass lesion in the seven patients with unilateral masses and prominent asymmetric, (R greater than L) bilateral uptake in the patient with bilateral masses despite the fact that there were no obvious abnormalities of adrenocortical or adrenomedullary function as determined from peripheral blood and 24-hr urinary hormone measurements. Simultaneous bilateral adrenal vein catheterization (AVC) was employed to measure the levels of hormone effluent from the adrenal cortex and medulla and in all instances the cortisol concentrations were greatest from the side of the mass lesion in those patients with unilateral masses and from the larger of the two adrenals in the patient with bilateral adrenal masses. Thus, there was congruence between the anatomic (CT) and functional (NP-59 scintigraphy and AVC) investigations that depicted asymmetry of the adrenal glands which were not associated with abnormalities of overall adrenal function or hypothalamic-pituitary-adrenal axis integrity.

Adosterol↗
PubMed1986

The effect of the suspensor and gibberellic acid on Phaseolus vulgaris embryo protein synthesis.

The role of the suspensor in the early development of the dicot embryo has been described as merely an anchor or, conversely, as the major route of nutrients into the embryo. In order to further elucidate the role of the suspensor we have examined protein synthesis in early 0.2-mm and late heart stage 0.5-mm Phaseolus vulgaris (var. Taylor's Horticultural) embryos in tissue culture. Protein synthesis was examined in embryos and suspensors. Our results showed that in 0.2-mm embryos virtually all protein synthesis was dependent on an attached suspensor. Maximum protein synthesis in 0.5-mm embryos was observed when embryos were cultured attached to the suspensor. The levels were moderately decreased when the embryo was cultured detached from or without the suspensor. Gibberellic acid at 10(-6) to 10(-7) M elicited the same protein diversity and greater [35S]methionine incorporation than did the attached suspensor in 0.2-mm embryos. Embryos of 0.5 mm did not appear to be differentially responsive to various gibberellin concentrations.

Culture Techniques↗
PubMed1986

Tumor size dependent changes in a murine fibrosarcoma: use of in vivo 31P NMR for non-invasive evaluation of tumor metabolic status.

Tumor tissue contains viable hypoxic regions that are radioresistant and often chemoresistant and may therefore be responsible for some treatment failures. A subject of general interest has been the development of non-invasive means of monitoring tissue oxygen. Pulse Fourier transform 31P NMR spectroscopy can be used to estimate intracellular nucleotide triphosphates (NTP), phosphocreatinine (PCr), inorganic phosphate (Pi) and pH. We have obtained 31P NMR spectra as an indirect estimate of tissue oxygen and metabolic status in a C3H mouse fibrosarcoma FSaII. Sequential spectra were studied during tumor growth in a cohort of animals and peak area ratios for several metabolites were computed digitally by computer. During growth, tumors showed a progressive loss of PCr with increasing Pi, and most tumors greater than 250 mm3 in volume had little or no measurable PCr. The smallest tumors (38 mm3 average volume) had PCr/Pi ratios of 1.03 +/- .24, whereas tumors 250 mm3 or more had an average PCr/Pi ratio of 0.15 +/- .04. Similarly derived NTP/Pi ratios decreased with tumor size, but this change was not significant (p = .17). Radiobiologic hypoxic cell fractions were estimated using the radiation dose required to control tumor in 50% of animals (TCD50) or by the lung colony technique. Tumors less than 100 mm3 had a hypoxic cell fraction of 4% (TCD50) while tumors 250 mm3 had a 40% hypoxic cell fraction (lung colony assay). These hypoxic fraction determinations correlated well with the depletion of PCr and decline in NTP/Pi ratios seen at 250 mm3 tumor volumes. Tumor spectral changes with acute ischemia were studied after ligation of the tumor bearing limb and were similar to changes seen with tumor growth. PCr was lost within 7 minutes, with concurrent increase in Pi and loss of NTP. Complete loss of all high energy phosphates occurred by 40 minutes of occlusion. In vivo tumor 31P NMR spectroscopy can be used to estimate tissue metabolic status and may be useful in non-invasive prediction of hypoxic cell fraction, reoxygenation, and radiation treatment response.

Animals↗
PubMed1985

The effect of the suspensor and gibberellic acid on Phaseolus vulgaris embryo protein content.

The role of the suspensor in the early development of the dicot embryo has not yet been defined. It has been described as merely an anchor and also as the major route of nutrients into the embryo. In order to further elucidate the role of the suspensor, early 0.2-mm and late heart stage 0.5-mm Phaseolus vulgaris (var. Taylor's Horticultural) embryos have been examined in tissue culture. It is known that Phaseolus embryos in culture at low osmotic potential will germinate precociously and that embryos in culture at high osmotic potential will either fail to grow or form callus. Optimum sucrose concentrations for continued, normal embryonic development of 0.2 mm and 0.5 mm P. vulgaris in tissue culture with Gamborg B5 medium were determined to be 12 and 6%, respectively. Protein content was examined in embryos and suspensors. Results showed that both 0.2- and 0.5-mm embryos required an attached suspensor for maximum protein content. Protein levels were substantially decreased when the embryo was cultured detached from or without the suspensor. Gibberellic acid at 10(-6) to 10(-7) M restored the protein content to that of freshly excised embryos.

Culture Techniques↗
PubMed1985

Magnetic resonance imaging of the interatrial septum and atrial septal defects.

Magnetic resonance images were obtained in six patients with known or suspected interatrial septal defects (ASD) and 33 subjects without congenital heart disease. Image planes were oriented to the long and short axes of the left ventricle and septum and provided reproducible display of pertinent anatomic landmarks. Of the images in 33 control subjects, three (9%) were falsely positive showing apparent ASD. ASDs were correctly identified and localized in all six patients (five secundum, one primum). Long-axis views provided excellent display of the location and diameter of defects. All were confirmed at cardiac catheterization and four at surgery with good agreement in measurement of defect size and location. All showed signs of right-sided volume overload. Five had previous echocardiography, which showed definite or suspected ASD in four.

Adult↗
PubMed1985

Study of vitreous liquifaction by NMR spectroscopy and imaging.

The vitreous gel is primarily composed of collagen, hyaluronic acid, and water (98-99%) and can break down into a liquid state devoid of collagen. The liquifaction of vitreous gel that occurs with age and in certain other disease states is believed to be important in the pathogenesis of retinal tears and detachments. The authors report measurements of water proton relaxation times and water proton nuclear magnetic resonance (NMR) imaging to study the process of vitreous liquifaction in extracted vitreous and in the intact bovine eye. A comparison is made between macroscopic viscosity, longitudinal (T1) and transverse (T2) relaxation times obtained on an NMR spectrometer and proton NMR images. Vitreous liquifaction as measured by a decrease in macroscopic viscosity resulted after treatment of vitreous with collagenase and to lesser degree with hyaluronidase. A shortening of relaxation times accompanied the drop in viscosity. An area of brightness or increased proton signal intensity corresponding to a focus of liquifaction was seen by NMR imaging only after injection with collagenase. The authors believe NMR imaging to be a useful new diagnostic modality by which vitreous liquifaction can be studied in the intact eye. The vitreous provides a new model for studying changes in proton relaxation times of protein solutions in biologic systems.

Animals↗
PubMed1984

Nuclear magnetic resonance imaging of the vitreous body.

Imaging with proton nuclear magnetic resonance is a valuable new tool for studying the vitreous body of the eye. It is particularly suited for the detection of vitreal liquefaction and intraocular hemorrhage because of the dependence of the signal on the physical environment of water. Conversely, the vitreous body provides a new model for studying changes in proton relaxation times of protein solutions in biological systems.

Animals↗
PubMed1981

Induction of tyrosine aminotransferase by pyridoxine in Drosophila hydei.

Salivary glands incubated in various concentrations of pyridoxine (Vitamin B6) show increasing tyrosine aminotransferase (TAT) activity at concentrations up to 10(-5) M and then decreasing activity up to 10(-2) M but in all cases the activity is greater than that of the controls. This increase in activity is demonstrable for up to 6 h, the longest period tested, and is dependent on the synthesis of new mRNA. A similar increase in TAT activity is observed in salivary glands subjected to heat shock. Antibodies prepared against purified tyrosine aminotransferase precipitate a peptide of the same molecular weight (40 KD) as that induced by pyridoxine.

Animals↗
PubMed1979

The normal dexamethasone-suppression adrenal scintiscan.

To establish the parameters of adrenal imaging under dexamethasone suppression (DS), 18 normotensive, normal male volunteers underwent dexamethasone-suppression adrenal scintiscanning. Five control groups were established and given dexamethasone, either 8 mg for 2 days or 4 mg for 7 days before 6 beta-[131I]iodomethyl-norcholesterol (NP-59) administration. NP-59 was given in doses of 2, 1, or 0.5 mCi. Early visualization (3--5 days) of the adrenals was noted in the groups on the 8 mg DS regimen with either 1 or 2 mCi of NP-59. Late visualization (5--7 days) was noted in the groups that received 4 mg DS and either 2, 1, or 0.5 mCi of NP-59, respectively. The normal adrenal will demonstrate uptake of NP-59 under DS, and the duration of DS before imaging is the critical factor as to when discernible adrenal visualization will occur. The documentation of the noraml suppression interval on these DS regimens provides a basis for the correct diagnostic interpretation of adrenal hyperfunction as seen on the dexamethasone-suppression NP-59 adrenal scan.

Adosterol↗
PubMed1977

Parental origin of the extra chromosome in Down's syndrome.

Chromosome 21 fluorescent heteromorphisms were studied in 42 patients with Down's syndrome, their parents and their siblings. Included in this number are two instances of an aunt and niece affected with trisomy 21, and one of affected siblings. One case has a de novo 21/21 translocation. Blood group, red cell and serum protein markers were also studied for linkage, gene exclusions, associations, and paternity testing. Thirty-one of the trisomy 21 cases were informative for parental origin of the extra chromosome and for stage of meiosis. The non-disjunctional event was of maternal origin in 24; 23 occurred in meiosis I, 1 in meiosis II. Seven were of paternal origin; 5 in meiosis I, and 2 in meiosis II. The translocation case was of paternal origin. A literature search revealed a total of 98 cases informative for the parent of origin of the extra chromosome, of greater than 347 families tested. In addition, 3 de novo translocation cases, of 7 tested, were informative. The data suggest that most cases result from an error in the first meiotic division in the mother, but that a significant proportion are paternal in origin.

Adult↗
PubMed1977

Scanning electron microscopy of isolated Chironomus polytene chromosomes.

Individual polytene chromosomes have been isolated from Chironomus stigmaterus for scanning electron microscope observations. The three dimensional ultrastructure of these chromosomes consists of a series of chromatin strands extended in the interbands and more tightly coiled or folded in the banded regions. The nucleolus is observed to be a dense disc or doughnut shaped structure surrounding the chromosome while the Balbiani Rings appear as diffuse regions consisting of both fibrillar and granular elements.

Animals↗
PubMed1976

Computer simulation of local anesthetic effects using a mathematical model of myelinated nerve.

A mathematical model of myelinated axon was programmed for digital computer solution of the consequences of the conduction characteristics when the model membrane was affected by local anesthetics simulated by alteration of the ionic conductance parameter. The effects of tetrodotoxin on impulse conduction were studied in detail by means of a systematic reduction in sodium conductance in 1 to 10 nodes of Ranvier. Rhis technique simulates the method used experimentally and clinically to achieve a conduction block with the circumscribed application of local anesthetics to segments of nerve axons or nerve trunks. The analysis of the tetrodotoxin "dose-response" relationships revealed the fact that the model myelinated axon could support three types of conduction when depressed by this drug. One type of conduction of a subnormal impulse at the nodes of Ranvier; a second is characterized by a form of decremental conduction in which the rate of decrement of the nodal impulse is linear with distance. The third type is a second form of decremental conduction which is exponential in configuration and is seen when the g(Na) at the nodes of Ranvier is reduced to less than 27% of normal. Parallel experiments were performed to simulate the effects of lidocaine and some significant differences were observed. Analysis of the action potentials within the internodel region suggests that, although immune to drug action in the model, the internodal segment affects the generation of action potentials at the nodes. A commentary is presented on the limitations of the model as it reflects known pharmacologic relationships in real myelinated axons.

Anesthetics, Local↗
PubMed1976

Cytogenetic darkroom magic: now you see them, now you don't.

Customary procedures used to determine chromosomal inheritance do not disclose many of the chromosomal polymorphisms known to be present, resulting in uninformative families. The sequential printing of individual chromosomes presented here is a technique that has increased the number of informative families in our studies. This technique has revealed previously unseen heritable chromosome differences and allowed the designation of parental origin.

Chromosomes, Human, 21-22 and Y↗