Timothy Merz

Effect of Mitomycin C on Lateral Root-Tip Chromosomes of Vicia faba

Lateral root-tip chromosomes of Vicia faba were treated with mitomycin C. Chromatid aberrations were observed from 24 through 96 hours after treatment. The effect of mitomycin C was not altered appreciably by changes in pH, temperature, oxygen tension, or lack of adenosine triphosphate. The relationship of mitomycin C to other radiomimetic compounds is discussed.

An alternative pathway of cerebrospinal fluid absorption in communicating hydrocephalus. Transependymal movement.

After induction of communicating hydrocephalus in 5 primates and 30 dogs, auto-radiographs following a slow intraventricular infusion of 131I albumin demonstrated marked transependymal radiopharmaceutical migration in these animals to a much greater extent than in normal subjects.

Radiosensitivity and repair time: The repair time of chromosome breaks produced during the different stages of the cell cycle ☆

Abstract The repair times of X-ray-induced chromosomal breaks produced at different stages of the cell cycle were studied. Human peripheral lymphocyte cultures were used because of their “relative” synchronous character. The repair time in G 1 and S was observed to be 90 min. In late S and G 2 the repair time was 60 min. The 30-min decrease in repair time in G 2 was thought to be due to a change in the repair system itself rather than the cells commitment to division. The possibility that repair efficiency may well be dictated by factors preceeding the repair act is discussed.

Factors Influencing the Effect of β-Propiolactone on Chromosomes of Vicia faba

The effect of β-propiolactone on chromosomes is independent of pH, oxygen tension, and some metabolic inhibitors. It is influenced by temperature, concentration, and pretreatments with dinitrophenol. henol. Interphase sensitivitycalizationand localization of breaks are discussed in terms of the action of β-propiolactone and the relationship of γ-propiolactone to other radiomimetic compounds.

Chromosome Number of the Chimpanzee, Pan troglodytes

The chromosome numbers of nine chimpanzees (Pani troglodytes) have been determined by the bone marrow technique. The diploid number in this species is 48, with a probable XX-XY sex chromosome constitution.

INTERACTION OF CHROMATID BREAKS PRODUCED BY X-RAYS AND RADIOMIMETIC COMPOUNDS

The results of combination treatments of the roots of Vicia faba with certain radiomimetic compounds (8-ethoxycaffeine, maleic hydrazide, β-propiolactone, potassium cyanide) and x-ray as well as combination treatments of certain radiomimetic compounds with one another were observed to determine whether interaction will occur between chromosomal breaks induced by different agents. Interaction was observed between breaks induced by x-rays and all of the breaks induced by chemicals but not between breaks induced by any two chemicals. The results are discussed in terms of possible breakage bond differences and the effects of temporal and spatial differences in breaks induced by different agents.

Radiological features of the most common autosomal disorders: Trisomy 21–22 (Mongolism or Down's syndrome), trisomy 18, trisomy 13–15, and the cri du chat syndrome

Four autosomal disorders are described; trisomy 21 (mongolism or Downs syndrome), trisomy 18, trisomy 13–15 and ‘cri du chat’ syndrome. These disorders are associated with patterns of clinical and radiographic abnormalities that are characteristic. The typical karyotypes, clinical manifestations, radiographic findings, and differential features are presented.

Semiquantitative studies of transependymal albumin movement in communicating hydrocephalus.

Quantitative autoradiography was performed in 6 dogs with chronic communicating hydrocephalus and the results compared with a normal study. Transependymal migration of labelled albumin into the enlarged periventricular extracellular space (ECS) was demonstrated. Graphic representation on probability paper of the radioactivity per unit distance from the ventricular ependyma toward the cortex suggests that diffusion is the mechanism operative in normal animals. In those with communicating hydrocephalus, the character of the graph suggests facilitated diffusion.

UNUSUAL CHROMOSOMES AND MALIGNANT DISEASE

Abstract Aberrant A-group chromosomes (particularly one abnormally long no. 2 chromosome) in the karyotypes of individuals with a family history of tumours have been observed. The variant chromosomes were seen only in individuals with a family history of cancer. When present the variant chromosomes have been observed in a majority of cells examined. They also have been shown in more than one tissue.

Transventricular albumin absorption in communicating hydrocephalus

SummaryThe movement of radioactive labelled albumin (RISA) after intraventricular or intrathecal injection from the cerebral ventricular system into the brain parenchyma has been observed in six dogs with experimental communicating hydrocephalus as well as in a control group. Autoradiography with determination of grain counts per brain-tissue unit was performed to obtain the relation of radiopharmaceutical tissue-concentration versus distance from the ependymal lining. 4 h after injection there was a significant higher tissue-concentration of RISA in the hydrocephalic than in the control group. The distribution in normal animals appears to be consistent with diffusion into the extracellular space of the brain; whereas in hydrocephalic animals intracerebral bulk flow with alteration of the cerebrospinal fluid-brain barrier is suggested.ZusammenfassungNach intraventrikulärer oder intrathekaler Injektion von radioaktiv markiertem Jodserumalbumin (RISA) wird dieses Radiopharmazeutikum sowohl bei 6 Hunden mit experimentellem, kommunizierendem Hydrocephalus als auch bei einer Kontrollgruppe vom Ventrikelsystem in das Gehirnparenchym aufgenommen.Das Verhältnis zwischen RISA-Konzentration im Hirngewebe und Entfernung vom Ventrikelependym wurde durch Autoradiographie mit Bestimmung der Silberpunkte pro Gewebseinheit durchgeführt.Die Gewebskonzentration von RISA ist nach 4 Std in der Hydrocephalusgruppe wesentlich höher als bei den Kontrolltieren. Die Verteilung kann bei normalen Tieren durch Diffusion erklärt werden. Bei Hydrocephalustieren wird ein intracerebraler Transportfluß mit Veränderung der Liquor-Hirn-Schranke angenommen.