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S Elias

Publications and source records attributed to S Elias.

7 recordsLinked to original sources
PubMed1979

Localization of the nucleolar organizer by computer-aided analysis of a variant no. 21 in a human isolate.

A variant chromosome no. 21 consisting of two stalks and two satellites in tandem was detected during a survey of a human isolate. The variant segregated in three generations of a large kindred. One male had the variant no. 21, a metacentric Y, and a 47,XXY complement; however, no other evidence of chromosomal nondisjunction was found. Computer-aided analysis of sequentially stained variant no. 21 chromosomes indicated that silver-stained material corresponded to the proximal stalk region (as defined by Giemsa), but often covered both the distal stalk and satellite (also as defined by Giemsa). These data support the hypothesis that human nucleolar organizers are localized to the stalks of acrocentric chromosomes.

Azure Stains↗
PubMed1979

Analysis for amniotic fluid crystallization in second-trimester amniocentesis.

A potential complication of second-trimester amniocentesis for genetic indications is inadvertent needle insertion into the maternal bladder, resulting in aspiration of urine rather than amniotic fluid. Amniotic fluid forms a characteristic crystalline arborization pattern when allowed to air dry. We utilized this property of amniotic fluid to distinguish amniotic fluid from maternal urine. In 24 of 25 cases studied in a randomized blind fashion the crystalline arborization test correctly identified amniotic fluid, whereas none of the 25 urine samples showed this pattern. Our study indicates that the crystalline arborization test is reliable in distinguishing amniotic fluid from maternal urine during the second trimester of pregnancy.

Amniocentesis↗
PubMed1978

Comparative effects of tritiated water and thymidine on the preimplanted mouse embryo in vitro.

Preimplanted mouse embryos were cultured in an in vitro-system from the two cell stage to blastocysts. In the control cultures about 92% of the incubated embryos developed to blastocysts. When tritiated compounds like tritiated water or tritiated thymidine were present in the incubation medium the number of blastocysts decreased with increased medium tritiated thymidine was about one thousand times more effective than tritiated water. Tritiated thymidine caused a more pronounced division delay than tritiated water which had a strong effect on the blastulation process. Further studies showed that the incorporation of tritiated thymidine into the DNA lead to high concentrations of tritium in the cell nucleus. Dose calculations are performed for the cell nucleus in the case of incubation with tritiated thymidine as well as with tritiated water. The different action of the tritiated compounds can apparently be explained by the specific incorporation of thymidine into the DNA.

Animals↗
PubMed1977

Accelerated degradation of acetylcholine receptor from cultured rat myotubes with myasthenia gravis sera and globulins.

Altered geometry of the neuromuscular junction and a decreased number of acetylcholine receptors appear responsible for the defect of neuromuscular transmission in myasthenia gravis. We have used cultured rat myotubes as a model to study in vitro the potential role of myasthenic globulins in the pathological process. Acetylcholine receptor content was assayed by the extent of 125I-labeled alpha-bungarotoxin binding, and acetylcholine receptor function was assayed by the sensitivity to acetylcholine iontophoresis. The half-life of the acetylcholine receptor was 18.5 hr in the presence or absence of control sera. Myasthenic sera and globulins produced a gradual reduction in acetylcholine receptors, as assessed by biochemical and electrophysiological techniques. The half-life in the presence of myasthenic sera was 6 hr. The accelerated turnover was unaffected by puromycin but was slowed by lowered temperature (18-20 degrees), interference with energy metabolism (2,4-dinitrophenol), and interference with cytoskeletal structures (colchicine and cytochalasin B). We found no electrophysiological evidence to suggest globulin blockade of acetylcholine access to the acetylcholine receptor. Our observations suggest that circulating globulins in myasthenia gravis may contribute to the functional defects of neuromuscular transmission by accelerating the rate of internationalization and degradation of surface membrane acetylcholine receptors.

Acetylcholine↗
PubMedDate not supplied

Preservation of the laryngeal nerves during total thyroid lobectomy.

A technique of exposure and preservation of the recurrent laryngeal nerve at the very onset of thyroidectomy and preservation of the external branch of the superior laryngeal nerve at the close of the procedure is described, which is believed to afford maximum protection to these nerves during total thyroid lobectomy and isthmusectomy as well as total thyroidectomy. At the same time, preservation of the parathyroid glands is achieved. In 120 exposures and preservations of the recurrent laryngeal nerve there have been no instances of a single permanent paralysis of this nerve. In 111 total thyroid lobectomies in which the external branch of the superior laryngeal nerve was placed in jeopardy, only one patient had a slight bowing of the vocal cord with excellent voice function during a limited follow-up period.

Arteries↗