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Biomedical subjects

S Yee

Publications and source records attributed to S Yee.

At least 37 records · Page 2Linked to original sources

Listeria-associated pericarditis in an AIDS patient.

Listeria monocytogenes is a pathogenic, facultative intracellular gram-positive rod, generally seen in cell-mediated immunocompromised states. In acquired immunodeficiency syndrome (AIDS), it most commonly presents as bacteremia or meningitis. An association with pericarditis has not been described previously in this group of patients. This article describes a case of pericarditis secondary to listeriosis involving a focal pancarditis and necrosis of the A-V node with subsequent refractory ventricular tachyarrhythmias in an immunodeficient patient presenting with altered mental status. Infectious etiologies should be considered for "benign" appearing pericardial effusions in AIDS patients and the diagnosis of listeriosis excluded in the presence of "diphtheroid-like" organisms.

Acquired Immunodeficiency Syndrome↗

Investigation of lens glycolytic enzymes: species distribution and interaction with supramolecular order.

Distribution of several glycolytic enzymes in the lenses of different vertebrate species and their organization in the calf lenses were studied. Though no general pattern of enzyme activities in different species is discernible, high activities of TPI followed, in decreasing order, by GAPDH, enolase, PK, LDH and aldolase appear to be more common. Our observation on the unusually high activities of aldolase in the pig, enolase in the sheep and LDH in the duck lens are interesting in view of the already known dual function of LDH as an enzyme and a structural protein (epsilon-crystallin) in duck. Controlled treatment with detergents Brij-58 and Triton X-100 caused distinctly differential purturbations in the lens cells. In spite of fiber membrane disruption and partial actin dissolution by Brij-58, no significant increase in the release of glycolytic enzymes compared to control was observed. This suggests that none of the enzymes existed as a completely soluble and freely diffusible fraction. But treatment with a strong detergent (Triton X-100) caused the release of higher amounts of enzymes suggesting either a direct or indirect interaction with the cytomatrix components. Aldolase appears to be maximally bound in the cytosol followed by TPI, GAPDH, LDH and PK in decreasing order. Although thin lens slices were incubated with the detergents for a total period of 40 min and the loss of fiber architecture and organization confirmed by light microscopy, in the Triton X-100 treated tissues less than 25% of the total activity of any enzyme except TPI appeared in the bathing medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Proton NMR investigation of the reconstitution of equine myoglobin with hemin dicyanide. Evidence for late formation of the proximal His93F8-iron bond.

Reconstitution of apoequine myoglobin (apoEqMb) with hemin dicyanide (FePPIX(CN)2) was monitored by 1H NMR spectroscopy to gain information about the sequence of events leading to metEqMbCN. At least one step in the pathway is slow enough to allow us to follow the time-dependence of formation of the product, a mixture of heme-insertion isomers characterized by others (Jue, T., Krishnamoorthi, R. and La Mar, G.N. (1983) J. Am. Chem. Soc. 105, 5701-5703; Lecomte, J.T.J., Johnson, R.D. and La Mar, G.N. (1985) Biochim. Biophys. Acta 829, 268-274). However, in contrast to all previously reported Mb-FePPIX reconstitutions, we find that the initial ratio of heme-insertion isomers is not 1:1. This mixture is, instead, found to be enhanced in the isomer which dominates at equilibrium. This is taken as evidence for a '[FePPIX(CN)2.EqMb]' intermediate which lacks the proximal His93F8-Fe bond and which proceeds quickly toward an equilibrium ratio of heme-insertion isomers. Therefore the heme-insertion isomer ratio is frozen only when the proximal His93F8-Fe bond is formed. The difference in this ratio of heme-insertion isomers between EqMb (4.5:1) and SwMb (2.5:1) likely reflects the amino acid substitution: Lys----Arg45CD3 (EqMb----SwMb).

Animals↗

One- and two-dimensional NMR relaxation studies of dynamics and structure in bile salt-phosphatidylcholine mixed micelles.

A series of one- and two-dimensional 1H-NMR relaxation measurements has been conducted on simple and mixed micellar aggregates of taurocholate, diphenylvaleroylphosphatidylcholine (diPVPC) and egg yolk phosphatidylcholine (egg PC). The results are interpreted to provide structural and dynamic comparisons between micelles and vesicles, between phospholipids of varying chain length, and between different lipid components within the same micellar aggregate. Both chemical shift changes and two-dimensional nuclear Overhauser effect cross peaks suggest direct interaction of taurocholate and PC chemical sites, although the latter observations may also be accounted for by PC-PC interactions. These experiments demonstrate the promise of NMR relaxation techniques for investigations of molecular organization in model substrate for lipolytic enzymes.

Bile Acids and Salts↗

Multipoint linkage analysis.

A formula is given for the advantage of n-point sampling, which approaches infinity with n. However, 2-point and 3-point analyses extract nearly all the information in such samples and at the same time communicate this information as lods and chi 2, which can be combined with other data by simple addition without reevaluation of the likelihood. When null interference is assumed, map distances and multiple recombination frequencies are inflated, and there is substantial loss of efficiency and of support for the correct order.

Animals↗

Construction of conditional lod tables from multiple-locus linkage data.

Although multipoint linkage data are becoming quite common, economical and efficient methods for presenting these data are not yet in use. Tables giving the full likelihood function would be very voluminous, whereas reduction to standard lods destroys part of the information. We suggest a special lod table representation which preserves nearly all the information about both gene order and genetic map distance at a great reduction in data presented. Conditional lods, coined "c-lods" to distinguish them clearly from ordinary lods, are calculated for distances between each adjacent pair of loci, with all distances among other loci in the system conditionally optimized. Thus, in an n-locus system, conditional lods are presented for the n - 1 adjacent pairs of loci only. The principal reason for reporting lod scores is the potential for combining data from separate studies to reach conclusive evidence for linkage and gene order. Because estimates of recombination are different in each set of data, the crux of the problem is to present scores that provide a close approximation to the true likelihood away from maximum likelihood (ML). The sum of conditional lods closely approximates the likelihood throughout the domain. Therefore, conditional lods contribute appropriately when mapping from several sources of data, so contradictory estimates can be reconciled efficiently.

Biometry↗

Combined analysis of genetic segregation and linkage under an oligogenic model.

For traits with incomplete penetrance, simultaneous segregation analysis and linkage analysis may offer increased information. Since the numerical properties of the mixed model are a drawback in this more complicated analysis, a second locus is substituted for the polygenic component yielding a simpler and more tractable oligogenic model. While less realistic, the simpler model is not easily discriminated from the mixed model, particularly when used on affection data rather than quantitative traits. Calculations for combined linkage and segregation analysis are described for nuclear families with pointers to account for sampling scheme.

Computers↗

A revised map of chromosome 1.

The genetic map of chromosome 1 reported by Keats, Morton & Rao (1981) has been updated using recent recombination data and regional assignments from the Galton Laboratory (King, 1982a) and from the current literature. A maximum likelihood mapping technique using pairwise recombination data without a chiasma map was developed, based on the principles of Rao et al. (1979) and Keats et al. (1981). The development of this new method was found to be necessary when inconsistencies were encountered using a method which combines recombination data and physical data through the chiasma map. These inconsistencies could be due to appreciable chiasma movement, incorrect physical assignments or technical and biological variation in lod scores.

Chromosome Mapping↗

Cerebellar ataxia due to procainamide toxicity.

It has become appreciated that drug levels of procainamide hydrochloride needed to suppress inducible ventricular tachycardia by programmed ventricular stimulation exceed the previously published therapeutic range. Cerebellar ataxia developed acutely in a patient receiving high-dose procainamide. This was associated with a marked increase in the serum drug level. Resolution occurred within three days after drug therapy was discontinued.

Administration, Oral↗

Estimation of haplotype frequencies.

Maximum likelihood estimates of haplotype frequencies in multilocus systems are often zero and so may be genetically inacceptable. Estimation problems are discussed, and preferable estimates are derived.

Alleles↗

Linkage studies in spinocerebellar ataxia (SCA).

Data are now available on 9 pedigrees in detail and 4 pedigrees as lod scores only. Linkage to HLA is significant (Z = 5.53 at recombination rates of 0.223 in males and 0.327 in females). Tight linkage is excluded. Nine pedigrees which appear to be typical olivopontocerebellar atrophy (OPCA I) have recombination rates of 0.150 in males and 0.300 in females. The remaining 4 pedigrees are clinically atypical or include discrepant data and give no evidence for linkage. The symbol SCA1 is proposed for a locus on chromosome 6 (loosely linked to HLA), at which at least one allele produces OPCA I (Menzel type). It is not yet clear whether other clinical types are determined by alleles at different loci, although this is suggested by several pedigrees, including a Danish pedigree of OPCA with dementia. Linkage evidence will be decisive in delineating the ataxias.

Adolescent↗

Comparison of successful and unsuccessful community-placed mentally retarded persons.

Differences in the characteristics of unsuccessful and successful community-placed clients were examined. Discriminant function analysis identified a maladaptive behavior factor and sex to be significant discriminators between the two groups. Unsuccessful clients manifested a significantly higher frequency of every maladaptive behavior assessed by the maladaptive variable. More males than females failed in community placement.

Adolescent↗

The likely region of overlap (LRO) method for physical assignment of loci.

Numerical analysis is applied to physical assignments of loci, providing point estimates, an LRO confidence interval, and a chi(2) test of consistency whether there is a smallest region of overlap (SRO) or not. Results are given for two examples and summarized for 81 loci in man.

Chromosome Mapping↗

Cultural and biological determinants of lipoprotein concentrations.

A general linear model is presented here for biological and cultural inheritance involving ten parameters to be estimated from 16 correlations in nuclear families, providing ample degrees of freedom to test goodness of fit. Applied to six lipoprotein traits the model fits acceptably to all, although there is evidence of transient maternal effects for cholesterol and lipemia. Genetic heritability in children ranges from 0.175 for triglyceride to 0.562 for total cholesterol. Cultural heritability in children ranges from 0.012 for VLDL to 0.149 for HDL-cholesterol.

Adult↗