Biomedical subjects
Publications and source records attributed to M S Lin.
Abnormal increased renal accumulation of Tc-99m-MDP was observed in a patient found subsequently to have stenosis of the ipsilateral renal artery. The case is both interesting in itself and for its possible implications regarding the use of radiolabeled phosphates in renal ischemia.
Bone scintigraphs in a case of ankylosing spondylitis exhibiting a characteristic involvement of sternal and spinal joints are described and discussed.
Indium-111-labeled leukocyte imaging is described in two cases of acute pancreatitis. The study correctly anticipated the absence in one case, and the presence in the other, of complicating abscesses.
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Somatic cell hybrids between mouse and human cells containing two different reciprocal translocations involving human chromosome 1, 46,X,t(1;X)(q12;q26) and 47,XX,+21,t(1;17)(p32;p13), were studied for the expression of human uridine diphosphate galactose 4-epimerase (UDPGal 4-epimerase, E.C. 5.1.3.2) by starch-gel electrophoresis. Analysis of the hybrid clones for the expression of the enzyme and the presence of the translocation chromosome 1 has permitted the assignment of the gene for human UDPGal 4-epimerase to the pter yields p32 region of chromosome 1.
A lateral asymmetry in the C-band region of human chromosomes is revealed by 4',6-diamidino-2-phenylindole (DAPI) fluorescence in amniotic cells grown for one replication cycle in the presence of 5-bromodeoxyuridine (BrdU). Short-arm segments and satellites of acrocentric chromosomes fluoresce as brightly with quinacrine as the distal part of the long arm of the Y chromosome, and also show a lateral asymmetry. This asymmetry appears to be correlated with highly repetitious DNA, including satellite fractions responsible for C-band staining, and may reflect an unequal distribution of thymine residues between the two polynucleotide chains of the DNA in the C-band region. The C-band region of chromosome 9 fluoresces brightly in both sister chromatids and appears to be symmetrical. This may be the result of multiple inversions in the C-band heterochromatic region.
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Whole body 99mTc-pyrophosphate scans were obtained and correlated with skeletal radiographs for detection of heterotopic calcification in 122 spinal injury patients. There were 27 patients with recent injury (less than 6 months) and 95 with injury of 6 months to 25 years duration. Ectopic calcification was detected in 8 of the 27 patients (30%) with recent injury and in 32 of the 95 (34%) with injury of over 6 months duration. Ectopic calcification seen on radiographs were also seen on scans in all instances. The scan was a sensitive indicator of the ectopic calcification particularly at its early stage, and detected its presence before observable radiographic changes in 5 patients with injury of 1-3 months duration. In 3 of the 5 patients, the ectopic calcification mimicked deep vein thrombosis in presentation, and the scan was valuable in identifying the nature of the complication.
Variations in lateral asymmetry of human chromosome 1 were studied in 17 amniotic cell samples and eight blood samples by the 5-bromodeoxyuridine (BrdU) quenching of 4'-6-diamidino-2-phenylindole (DAPI) fluorescence. The size and the relative proportion of the bright fluorescent spots on each chromatid in the heterochromatic region of chromosome 1 (1qh) are variable from different amniotic (or blood) samples after one cycle of BrdU incorporation. However, the particular pattern for a given chromosome 1 is consistent within the individual sample. Size variations were classified into three groups, and variations in the pattern (proportion) of bright fluorescence on each chromatid in the 1qh region were classified into four groups. A preliminary estimate of the type and frequency of lateral asymmetry variations was obtained. These results suggest a high frequency of variability of heterochromatin in the population. The BrdU-DAPI fluorescence technique was found to be very useful for characterizing variations in the 1qh region; variations in organization of heterochromatin DNA with the 1qh region can be detected, and a simple system of nomenclature is proposed for naming the variations in this region.
The optical absorption and fluorescence characteristics of 4'-6-diamidino-2-phenylindole (DAPI) with DNA and chromosomes were studied. There is a decrease in extinction coefficient and chift in the absorption spectra to a higher wavelength when the dye binds to DNA. The fluorescence of DAPI is enhanced by both A-T and G-C base-pairs. The enhancement by A-T rich is significantly greater than by G-C rich DNA. The chromosomes and the constrictions of human chromosomes 1 and 16; these regions are known to contain A-T rich DNA and show dull fluorescence when treated with quinacrine. This dye may be useful for identifying A-T rich region in chromosomes. The fluorescence of DAPI bound to polynucleotides or chromosomes is partially quenched by the introduction of BrdU. This suppression of dye fluorescence allows optical detection of sister chromatid exchanges and chromosome region containing DNA with an unequal distribution of thymidine between polynucleotide chains after BrdU incorporation.
Radial immunodiffusion was used to measure the concentrations of IgG, IgA, and IgM in the sera of 224 asthmatic children, ages 6 months to 14 years. IgM was greater than two standard deviations above age-matched normal values in 51% of these asthmatic subjects. Immunoglobulin profiles were repeated up to four years later in 29 individuals with elevated IgM and increased IgM synthesis was sustained in 14 of these asthmatic subjects. Serum IgE concentrations were elevated in 23 of 35 asthmatic patients. There was no statistical difference in mean IgE between asthmatic children with normal or increased IgM. The distribution of IgE in each group was similar. Only 10 of 224 subjects had an IgA concentration less than 2 SD below age-matched control subjects. The significance and possible mechanisms of hyper-M-immunoglobulinemia are discussed.
The first 111In chelate exhibiting hepatobiliary excretion, a 111In-phenolphthalexon, has been formulated and tested in rats. The preparation of the chelate is simple, reflecting its inherently high stability. Its capability for extended cholescintigraphy allowed distinct visualization of the gallbladder and the bowel to the level of the rectosigmoid in dogs. No lethality or acute toxicity was induced by administration of the chelate.
This paper describes a 4'-6-diamidino-2-phenylindole (DAPI) fluorescent technique for differentiation of sister chromatids and for the study of sister chromatid exchanges (SCE) in mouse chromosomes. The advantages of the DAPI fluorescent technique are also described. Differences in the occurrence of SCE between the centromeric heterochromatin (C-banded) and the chromosomal arm chromatin were studied in mouse cells (RAG) with or without mitomycin C treatment. Single strand exchanges between the DNA double helices in the sister chromatids were not detected. SCE and chromosome breakage appeared to occur more frequently in the centromeric region than in the chromosomal arm. This might play an important role in chromosome evolution in mice.
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Differential fluorescence of sister chromatids and sister chromatid exchanges (SCE) in chromosomes from human lymphocytes grown two replication cycles in medium containing 5-bromodeoxyuridine can be detected by fluorescence microscopy after staining with 4'-6-diamidino-2-phenylindole (DAPI). The DAPI fluorescence appears to be more stable than that of the dye 33258 Hoechst and may provide a more sensitive method for the detection of SCE.
Pulmonary distribution of an inhaled radioaerosol was analyzed in 20 cases of chronic obstructive pulmonary disease (COPD) and 8 of other OPD. Nonciliary/ciliary partition of the distribution correlated with the severity of airway obstruction and approximated 3:1 in mild and 1:3 in very severe obstruction. In nuclear images, the distribution featured contrast abnormalities of hyperdeposition and hypodeposition. Intense hyperdeposition most commonly occurred in hilar and perihilar large airways. In isolated instances, hyperdeposition almost certainly occurred focally at sites of partial bronchial obstruction and diffusely by expiratory trapping; hypodeposition occurred distally to bronchial obstruction and in areas of parenchymal loss.
Brain scintigraphy was described in a case of vertical (biparasagittal) epidural hematoma confirmed by contrast angiography. The anterior dynamic and static studies showed inferior displacement of the superior sagittal sinus, diagnostic of an epidural collection. Delayed static anterior and lateral images showed an increased vertical uptake with a crescentic and straight inner contour, respectively. A transaxial computed tomographic scan was negative.