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Biomedical subjects

J Zeiger

Publications and source records attributed to J Zeiger.

8 recordsLinked to original sources
PubMed1998

Survey of genetic counselors and clinical geneticists regarding recurrence risks for families with nonsyndromic cleft lip with or without cleft palate.

Nonsyndromic cleft lip with or without cleft palate (CL/P) is a common congenital malformation affecting about 1/1,000 caucasian infants. Although the familial clustering of CL/P has been studied thoroughly, estimation of recurrence risk for genetic counseling purposes can be difficult. A survey was mailed to 912 board-certified genetic counselors, 542 non-board-certified genetic counselors, and 776 board-certified clinical geneticists to investigate the recurrence risks they would assign to three example families with CL/P. Responses were received from 155 (17%) board-certified genetic counselors, 36 (6.6%) non-board-certified genetic counselors, and 100 (18.5%) board-certified clinical geneticists. No major differences were found in their responses, suggesting that for these three families, geneticists would provide similar estimates of risk, regardless of their amount of experience with oral clefts patients, where they are currently employed, or their board certification status.

Cleft Lip↗
PubMed1997

A comprehensive analysis of complex traits in problem 2A.

We used descriptive analysis to investigate the relationship between affection status and five quantitative traits (Q1-Q5) in Problem 2A and results suggested the five quantitative traits fall into two groups. The first group comprised three strongly correlated traits, Q1-Q3, which underlie affection status, and the second group comprised Q4 and Q5, which are not directly related to affection status. Segregation and linkage analyses of traits Q1-Q3 and affection status from the first replicate detected one of the major loci for Q1 (MG1) linked to marker 14 on chromosome 5 (D5G14). Because our segregation analysis failed to show evidence of a major locus effect on Q2, and we overlooked the interaction between MG3 and sex, we did not detect either MG2 or MG3. Using Haseman-Elston sib-pair analysis [Haseman and Elston, 1972], we also examined the statistical power of Q1 and type I error rate (using the environmental factor as an index), for the remaining 199 replicates in the context of a genome screen.

Chromosome Mapping↗
PubMed1994

Behavior of crayfish rhodopsin and metarhodopsin in digitonin: the 510 and 562 nm "visual pigments" are artifacts.

The visual pigment of the main rhabdom of the crayfish (P533) is unstable in digitonin. While slowly hydrolyzing to N-retinylidene opsin, a portion passes through a long-lived intermediate (P'505) with absorption similar to metarhodopsin but with the retinal still in the cis configuration. Crayfish metarhodopsin (M515) is similarly unstable in digitonin, and a portion converts to M'508 while bleaching slowly in the dark. Both P'505 and M'508 are light sensitive and bleach through an intermediate absorbing at still shorter wavelengths, M'460. The photobleaching of M'508 is likely a two-photon process, possibly involving P'505 as an intermediate. The persistence of these altered forms of the pigment with lambda max near 510 nm has compromised earlier efforts to analyze extracts of crayfish rhodopsin by partial bleaching. First, because of the incomplete decay of M515 (a portion of which liners as M'508), the difference spectrum for a red light exposure followed by dark decay has lambda max at 562 nm, but this difference spectrum does not describe a pigment. Because of the photosensitivity of M'508, a second bleaching exposure reveals the presence of a pigment with lambda max near 510 nm, but it is not a visual pigment and it is not present in the extract initially.

Animals↗
PubMed1989

Spectral properties of porphyropsin from an invertebrate.

Winter crayfish (Procambarus clarkii) contain both retinal and 3-dehydroretinal, as first described by Suzuki, Makino-Tasaka and Eguchi (1984). Using the detergent L-1695 we have extracted visual pigments from the rhabdoms of crayfish and have characterized spectrally both rhodopsin (P1) and porphyropsin (P2). Both P1 and P2 are converted by light to relatively stable meta-pigments (M1 and M2). We here show a method for estimating the absorbance spectra of all four pigment species. The spectra of P533(1) and M510(1) agree with previous microspectrophotometric measurements on isolated rhabdoms. P567(2) and M537(2) represent the first 3-dehydroretinal-based visual pigment system to be characterized from an arthropod.

Animals↗
PubMed1984

Imbalance of total cellular nucleotide pools and mechanism of the colchicine-induced cell activation.

Treatment with colchicine or vinblastine, both inhibitors of microtubule assembly, renders quiescent 3T3 cells in an "activated state" as evidenced by induction of DNA synthesis and other criteria. Microtubule disassembly caused by colchicine or vinblastine brings about a dramatic expansion of total cellular UTP pools with a concomitant diminution in total cellular ATP pools, thus resulting in a marked imbalance in total cellular nucleotide pools. Colchicine and vinblastine also stimulate total cellular RNA synthesis without enhancing uridine phosphorylation, suggesting that these drugs affect the G1 phase of the cell cycle at a point beyond the enhancement of uridine phosphorylation that usually accompanies mitogenic stimulation of quiescent mammalian cells. The markedly expanded cellular UTP pools appear to be necessary for initiation of the colchicine-stimulated DNA synthesis because decreasing cellular UTP pools by addition of D-glucosamine results in a selective inhibition of DNA synthesis in the colchicine-stimulated, but not control, cells. Furthermore, D-glucosamine exerts its inhibitory effect only when it is present in the cultures within the first 14 hr after colchicine treatment. When added at 21 hr, D-glucosamine still decreases cellular UTP pools, but it is no longer inhibitory for DNA synthesis, which commences 14-16 hr after colchicine stimulation. Taxol, an antitumor drug, prevents microtubule disassembly and also blocks such events as expansion of total cellular UTP pools and stimulation of RNA and DNA synthesis, indicating that microtubule depolymerization acts as a primary event initiating the process of cell activation induced by colchicine.

Adenosine Triphosphate↗
PubMedDate not supplied

Packaging of rhodopsin and porphyropsin in the compound eye of the crayfish.

The distribution of 3-dehydroretinal (Ral2) in dorsal, middle, and ventral slices of eyes of the crayfish Procambarus clarkii was examined by HPLC. No pronounced differences were found. Similar results were obtained when the eyes were cut into anterior, intermediate, and posterior portions. Dichroic difference spectra were measured in single halves of microvillar layers of isolated rhabdoms and the proportions of rhodopsin (P1) and porphyropsin (P2) estimated by comparison with computer-generated mixtures of these pigments, whose spectra are known from previous work. The fraction of visual pigment that is porphyropsin appears to be uniform throughout individual retinular cells and among the retinular cells of individual rhabdoms, but various substantially among different rhabdoms from the same eye. The interommatidial variation in the amount of P2 greatly exceeds the gross regional variation in Ral2. This means there is an intermingling of ommatidia with different levels of P2. The variability in P2 among ommatidia is not likely to have important implications for the vision of the crayfish but suggests that in the metabolism of retinoids, individual ommatidia are quasi-independent metabolic units. The results are compatible with a single opsin for both crayfish rhodopsin and porphyropsin.

Animals↗