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Biomedical subjects

A Jong

Publications and source records attributed to A Jong.

At least 19 recordsLinked to original sources
PubMed1990

CDC6 mRNA fluctuates periodically in the yeast cell cycle.

Using cultures synchronized by two independent procedures, alpha-factor arrest and centrifugal elutriation, we have investigated the expression of the Saccharomyces cerevisiae CDC6 gene through the cell cycle. Our results show that the CDC6 gene is periodically expressed in the yeast cell cycle. The level of CDC6 transcripts increases in late G1, reaching a peak (approximately 10-20-fold over the initial level) at about the G1/S phase boundary. The peak of CDC6 mRNA was observed to overlap or slightly precede that of the CDC8 message, and to obviously precede that of the histone H2A message by some 25 min. Unlike histone H2A mRNA, the CDC6 mRNA as well as CDC8 mRNA were not affected by hydroxyurea treatment. These results suggest that regulation of H2A mRNA is different from that of CDC6 or CDC8. We have studied the 5'-flanking regions of CDC6 and other cell cycle-regulated genes. DNA sequence analysis of the CDC6 promoter revealed two sequences, 5'-C/GACGCGNC/G-3' and 5'-PuGNAGAAA-3' (where Pu is a purine, and N is any nucleotide), which are repeated three times each. Similar sequence elements have also been found among several cell cycle-regulated genes, including the CDC8 gene, but are not found upstream of histone genes. The possible significance of these elements is discussed.

Base Sequence↗
PubMed1989

Human deoxycytidine kinase. Sequence of cDNA clones and analysis of expression in cell lines with and without enzyme activity.

Deoxycytidine kinase (dC kinase) is the rate-limiting enzyme in the anabolism of important anticancer and retroviral nucleoside derivatives. Its activity is often decreased in resistance to these drugs. To analyze the structure, function, and control of this clinically important enzyme we isolated 15 cDNA clones for human deoxycytidine kinase from lambda gt11 thymus and Molt 4 libraries. Four clones were sequenced. The largest clone is 2.9 kilobases and codes for a 626-amino acid open reading frame. The DNA and deduced amino acid sequence of the human dC kinase clones are homologous with a previously unidentified murine cDNA clone p3.4J (EMBL:MM34j) reported to be related to granulocyte-macrophage colony-stimulating factor. Deoxycytidine kinase also has cysteine-rich regions that are homologous with thioredoxin, the beta subunit of prolyl 4-hydroxylase, phosphoinositide-specific phospholipase C, thyroid hormone-binding protein, and protein disulfide isomerase. No differences were seen in the amount and size of deoxycytidine kinase protein and mRNA between CCRF/CEM and L1210 leukemic cell lines that express and do not express enzyme activity. Genomic restriction fragments were similar between the active and inactive CCRF/CEM cell lines. These data suggest that the cells deficient in dC kinase activity have a small defect in the structural gene.

Amino Acid Sequence↗
PubMed1989

Isolation of multiple types of plasminogen activator inhibitors from vascular smooth muscle cells.

Large arteries have a natural resistance to tumor cell invasion thought to be due to the production of protease inhibitors. Vascular smooth muscle cells (VSMC) representing the major cellular part of arteries were isolated from human aortas and grown in tissue culture. These cells were found to produce large amounts of inhibitors of plasminogen activators (PA). Fractionation of VSMC-conditioned medium by heparin-affigel chromatography separated three immunologically and functionally distinct PA inhibitors (PAI), namely PAI-1, PAI-2 and protease-nexin I. The three inhibitors were characterized by functional assays and immunoblotting. PA inhibitor 2 (PAI-2) had little affinity for heparin, whereas PA inhibitor 1 (PAI-1) bound to heparin and was eluted from the column at NaCl concentrations of 0.1 to 0.35 M. Protease-nexin I, eluted at NaCl concentrations of 0.5 M and higher. Most of the PAI-1 was present in the latent, inactive form. PAI-1 was further purified by ion exchange chromatography on a Mono-Q column. Partial sequencing of the purified PAI-1 confirmed its nature by matching completely with the sequence deduced from the cDNA nucleotide sequence of endothelial cell PAI-1. Thus, human VSMC produce all three presently known PAI and these can be separated in single heparin affinity purification step.

Amino Acid Sequence↗
PubMed1986

Yeast DNA replication.

We have explored various strategies for exploiting the yeast genetic and biochemical system for understanding DNA replication. Because of the long time that has intervened between the isolation of random replication mutants of yeast and the identification of the gene products affected, an alternative approach to elucidating the molecular basis of replication has been needed. One such alternative involves purifying replication proteins, isolating the genes encoding them, and constructing the appropriate mutant from the cloned gene. We have applied this "reverse genetics" strategy to three different replication activities: DNA polymerases, single-stranded DNA binding proteins, and proteins that bind to autonomously replicating sequence (ARS) elements.

DNA Polymerase I↗
PubMed1979

The location of eggs retained in the oviducts of mares.

The oviducts of 24 mares were examined to determine the site of retention of unfertilized eggs. The ampullary-isthmic junction regions of 42 of the 48 oviducts were serially sectioned and examined histologically. The remaining parts of the oviducts were flushed and the flushings searched microscopically. Of 45 eggs located, 40 were in the sectioned segments of 24 oviducts and only 5 were in the flushings. All but one of the sectioned segments contained prominent masses of material obstructing the lumen, but these were apparently not the direct cause of egg retention since eggs were found on both sides of them.

Animals↗
PubMed1976

A community health center dental program in Boston, U.S.A.

In 1970, a community-based and federally funded dental program was established in Boston. The multiple objectives of this program included the following: provision of dental treatment; education of schoolchildren in dental health; support for community measures of prevention such as water fluoridation; support of job training programs in dental assisting for community residents; employment of community people; and sensitization and training in community health for dental students and auxiliaries. The program provided a number of dental services at a reasonable benefit-cost ratio of 0.87. Other endeavors included the development of a dental health program with community schools and the involvement of dental students in the delivery of care and in screening for children with dental treatment needs.

Adolescent↗
PubMed1976

The status of community advisory committees in dental education.

A questionnaire survey was undertaken to determine how prevalent community advisory committees have become in the nation's dental schools and what types of committees have been formed. Responses were received from 52 (90 percent) of the 58 dental schools. The data revealed the following: 1. Nine schools (17 percent) have developed consumer committees. 2. The number of committee members varies from five to 29. 3. All the committees are composed of consumer members and school representatives, and, in all but one committee, health care providers are represented. 4. Four (44 percent) committees have advisory functions only, while the remaining five (56 percent) play an advisory and policy-making role. 5. No committee planned formal training sessions for their consumer members. 6. Of the 43 schools (83 percent) without such a committee, seven (16 percent) replied they foresee implementing a consumer committee in the future.

Community Health Centers↗
PubMed1975

A comprehensive approach to dental health in a school population.

A program to provide school children with dental health education and preventive services was initiated by the Boston University School of Graduate Dentistry. This program utilized several generally untapped resources. The emphasis was on classroom education using teachers who were motivated by special workshops as well as students of dental auxiliary training programs. These dental auxiliary students under the supervision of a dental health educator were used to educate the classroom teachers as well as to teach children in the classroom. Direct dental services were also provided in the program in the form of preventive services utilizing an unused dental chair available at a school.

Boston↗