Herbert L. Cooper

Deletion of short arms of chromosome 4–5 in a child with defects of midline fusion

We have described a case of a child with multiple congenital anomalies, including defects of midline fusion and abnormal dermatoglyphies. Chromosome analysis revealed deletion of part of the short arm of a chromosome in group 4--5. Although autoradiography studies were not done in this ease, it clinically resembles one in which the deleted chromosome belongs to the late replicating pair of group 4--5. This ease, therefore, not only differs from the cat cry syndrome in its clinical manifestations, but may be a result of a deletion of one of the other chromosome pair in the group.

Aryl Hydrocarbon (Benzopyrene) Hydroxylase Is Stimulated in Human Lymphocytes by Mitogens and Benz[a]anthracene

A mixed-function oxidase that requires reduced nicotinamide adenine dinucleotide phosphate, is carbon monoxide sensitive, and is drug-metabolizing is present in human lymphocytes and is increased to different levels by treatment with phytohemagglutinin, pokeweed mitogen, and a polycyclic hydrocarbon.

Suppression of tropomyosin synthesis, a common biochemical feature of oncogenesis by structurally diverse retroviral oncogenes.

To identify proteins whose production may be altered as a common event in the expression of structurally diverse oncogenes, we compared two-dimensional electropherograms of newly synthesized proteins from NIH/3T3 cell lines transformed by a variety of retroviral oncogenes, from cellular revertant lines, and from a line (433.3) which expresses the v-ras oncogene in response to corticosteroids. Most alterations in the synthesis of specific proteins detected by this approach appeared to be the result of selection during prolonged cultivation and were probably unrelated to the transformation process. However, we detected seven proteins whose synthesis was strongly suppressed in cell lines transformed by each of the six retroviral oncogenes we studied and whose production was fully or partially restored in two cellular revertant lines. Suppression of two of these proteins was also correlated with the initial appearance of morphological alteration during corticosteroid-induced oncogene expression in 433.3 cells. These proteins (p37/4.78 and p41/4.75) were identified as tropomyosins, a group of at least five cytoskeletal proteins. Transformation by the papovaviruses simian virus 40 and polyomavirus caused no suppression of synthesis of these tropomyosins. This indicates that suppression of tropomyosin synthesis is not a nonspecific response by cells to being forced to grow with the transformed phenotype but is specifically associated with oncogenesis by diverse retroviral oncogenes. The results are consistent with the hypothesis that the different biochemical processes initiated by expression of structurally diverse retroviral oncogenes may converge on a limited number of common targets, one of which is the mechanism which regulates the synthesis of tropomyosins.

Posttranslational formation of hypusine in a single major protein occurs generally in growing cells and is associated with activation of lymphocyte growth

Growing lymphocytes perform a novel chemical modification of a single protein (Hy+: approximately 18 kd, pI approximately 5.1), resulting in the formation of the unusual amino acid, hypusine (N epsilon-[4-amino-2-hydroxybutyl]lysine). This posttranslational event occurs only following activation of lymphocyte growth. Hypusine formation increases at a rate parallel to protein synthesis during the first 24 hr of growth stimulation, beginning before 6 hr of growth. At all times, hypusine is restricted primarily to the single protein, Hy+. In resting cells, the unmodified substrate protein, Hy0, is continuously synthesized and maintained in a steady-state pool of significant size. In several other cell lines, hypusine formation was also observed in a single protein of approximately 18 kd, pI approximately 5.1, indistinguishable electrophoretically from the lymphocyte protein. Thus Hy+ is a ubiquitous protein showing significant conservation among divergent species. Maintenance by resting lymphocytes of a pool of unmodified protein and early activation during growth of the hypusine-forming enzyme system suggest that this posttranslational modification may be of importance to lymphocyte activation.

Effects of inhibition of ribosomal RNA synthesis on the stimulation of lymphocytes by phytohaemagglutinin

Abstract Low concentrations of actinomycin inhibit the synthesis of ribosomal RNA preferentially in stimulated human lymphocytes. When ribosomal RNA synthesis was completely inhibited in this fashion there was still a substantial stimulation of the rate of lymphocyte protein synthesis by PHA, and persistence of some of the morphological changes typical of transformation. However, inhibition of ribosomal RNA synthesis was associated with inhibition of DNA synthesis and mitosis in lymphocytes incubated with PHA. Although these phenomena may be coordinately regulated, it is suggested that the low ribosome level may be an important factor preventing DNA synthesis, and thus cell division, by lymphocytes.

Rapidly labeled cytoplasmic RNA in normal and phytohaemagglutinin-stimulated human lymphocytes

Abstract 1. 1. Phytohaemagglutinin caused a significant stimulation of the incorporation of [ 3 H]uridine into RNA within 30 min of its addition to lymphocytes. While more than 90% of the radioactive RNA labeled in this period was in the nucleus, the stimulation of [ 3 H]uridine incorporation into RNA located in the cytoplasm was greater than the stimulation of incorporation into whole cell RNA. This rapid stimulation of the labeling of cytoplasmic RNA by phytohaemagglutinin might be important for the changes in lymphocyte protein synthesis that began at this time. 2. 2. Analysis by sucrose gradient centrifugation of the cytoplasmic RNA labeled in a 30-min pulse with [ 3 H]uridine showed that 4-S RNA was the predominant labeled species. However, gel filtration on Sephadex G-100 showed that this labeled RNA contained several components and that little of it was tRNA. Phytohaemagglutinin did not alter the elution pattern of the radioactive cytoplasmic RNA from Sephadex G-100 but stimulated the labeling of all its components to about the same extent. 3. 3. The predominant rapidly labeled cytoplasmic RNA species was retarded by Sephadex G-100 but eluted in a polydisperse fashion ahead of tRNA. This species was unstable to nuclease digestion and was not methylated. Its disappearance during an actinomycin chase was accompanied by the appearance of labeled tRNA. It did not seem to be attached to cytoplasmic particles, and it hybridized to lymphocyte DNA less readily than did nuclear polydisperse RNA. These properties are compatible with it being an unmethylated cytoplasmic precursor of tRNA. 4. 4. There was no evidence for an increase in the labeling of mature tRNA 30 min after the addition of phytohaemagglutinin, but such an increase was apparent after 90 min. After incubation of lymphocytes with phytohaemagglutinin for 20–24 h, the rate of tRNA synthesis was greatly stimulated. If the material discussed above is indeed a precursor to tRNA, the rate of its conversion to mature tRNA was also accelerated at this time.

Stimulation of interferon production in human lymphocytes by mitogens.

Summary Phytohemagglutinin (PHA), poke weed mitogen, and streptolysin-O, all agents capable of stimulating mitosis in human lymphocytes in vitro also stimulated the production of an antiviral substance with biological, chemical, and physical properties identical to those of human interferon. Upon removal of PHA from human lymphocyte cultures interferon production ceased within 2 hours. Readdition of PHA resulted in reinitiation of interferon production.

Mosquito Transmission of a Reticulum Cell Sarcoma of Hamsters

A transplantable reticulum cell sarcoma with leukemic manifestations can be transmitted from one hamster to another by means of a mosquito, A�des aegypti (L.). The transmission seems to be by a transfer of tumor cells, and not by passage of some other oncogenic agent.

Chromosomal aberrations in human disease. A review of the status of cytogenetics in medicine.

Abstract A brief history of the development of modern technics in human cytogenetics is presented, and application of these technics to the study of human disease is illustrated. The basic chromosomal defects in several disease states are described. The best studied conditions to date are mongolism, Klinefelters syndrome and Turners syndrome. In mongolism there is trisomy for the twenty-first autosome. In Klinefelters syndrome there is an XXY sex chromosome constitution. In Turners syndrome there is an XO sex chromosome constitution. The chromosome numbers in these conditions are, respectively, forty-seven, forty-seven and forty-five, whereas the normal human chromosome number is forty-six. Non-disjunction of chromosomes at meiosis, in the production of parental gametes, is postulated to be the mechanism for the production of the chromosomal aberrations in the three conditions mentioned. The process of non-disjunction is discussed in detail. It results in the production of parental gametes with either more or less than the normal haploid number of chromosomes. Fertilization involving such a gamete and another normal one may result in a zygote that is either trisomic for the chromosome involved or is deficient in one chromosome. Other types of chromosomal aberrations are considered. These include translocation, mosaicism, and isochromosome formation. The bearing of recent information on the theory of sex determination is also discussed.

Synthesis of Nonribosomal RNA by Lymphocytes: A Response to Phytohemagglutinin Treatment

When lymphocytes are stimulated to enlarge and divide by treatment with phytohemagglutinin, most of the rapidly synthesized RNA is nonribosomal. The phenomenon is a response by lymphocytes to stimulation by phytohemagglutinin, rather than a general concomitant of lymphocyte growth.