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Biomedical subjects

L K Cohen

Publications and source records attributed to L K Cohen.

14 recordsLinked to original sources
PubMed1992

Molecular attenuation of vaccinia virus: mutant generation and animal characterization.

These studies demonstrated that the inbred BALB/c mouse strain can be optimized for the assessment of vaccinia virus virulence, growth, and spread from the site of inoculation and immune protection from a lethal vaccinia virus challenge. The studies established that manipulation of the vaccinia virus genome generated mutants exhibiting a wide range of attenuated phenotypes. The nine NYCBH vaccinia virus mutants had intracranial 50% lethal doses that ranged from 2 to greater than 7 log10 units. The decreased neurovirulence was due to decreased replication in brain tissue. Three mutants had a decreased ability to disseminate to the lungs, brains, livers, and spleens of mice after intranasal infection. One mutant had a decreased transmission from mice infected by tail scarification to naive cage mates. Although the mutants, with one exception, grew to wild-type titers in cell culture, they showed a growth potential on the scarified skin of mice that was dramatically different from that of the wild-type virus. Consequently, all of the mutants had significantly compromised immunogenicities at low virus immunization doses compared with that of the wild-type virus. Conversely, at high immunization doses most mutants could induce an immune response similar to that of the wild-type virus. Three Wyeth vaccine strain mutants were also studied. Whereas the thymidine kinase, ribonucleotide reductase, and hemagglutinin mutants had a reduced virulence (50% lethal dose), only the thymidine kinase mutant retained its immunogenicity.

Administration, Intranasal↗
PubMed1991

Formation of lentivirus particles by mammalian cells infected with recombinant fowlpox virus.

Recombinant fowlpox viruses (FPV) containing the env or gag-pol genes of simian immunodeficiency virus from macaques (SIVmac) were constructed. The env, gag, and pol-encoded polypeptides were efficiently expressed and processed in avian cells productively infected with FPV as well as in mammalian cells, in which FPV infection is abortive. In addition, the recombinant FPV expressing the gag-pol genes directed the formation of defective, lentivirus-like particles which were released into the culture medium of infected cells. Coinfection of cells with the env and gag-pol recombinant viruses resulted in the generation of particles containing SIVmac envelope glycoprotein. The applications of this system to vaccine development are discussed.

Animals↗
PubMed1991

Utilization of DNA recombination for the two-step replacement of growth factor sequences in the vaccinia virus genome.

An efficient procedure for the generation of sequence-specific alterations of the vaccinia virus genome was demonstrated. Homologous DNA recombination within cells infected with vaccinia virus was used for the deletion or replacement of promoter sequences of the viral growth factor gene by a procedure comparable to transplacement in Saccharomyces cerevisiae. This DNA replacement procedure can potentially be used to generate any sequence alteration within the vaccinia virus genome. Deletion of growth factor promoter sequences resulted in a dramatic reduction in growth factor gene transcription and protein synthesis. Replacement of growth factor promoter sequences with promoter sequences of the strong constitutive 40-kDa gene resulted in an increase in gene transcription and protein synthesis and an altered temporal pattern of expression. Virus containing mutations in the growth factor gene demonstrated different plaque morphologies on cell culture monolayers.

Base Sequence↗
PubMed1990

Promoting oral health: guidelines for dental associations.

Dental associations throughout the world face many new challenges. For example, many industrial countries confront the potential of excess manpower to meet current demands, while developing countries try to cope with scarce resources to control existing and increasing disease levels. This guide is intended to facilitate the development of oral promotion programmes in both situations. In industrialized countries, an oral health promotion programme should increase awareness and interest among consumers, thus facilitating the conversion of unmet need to demand. In developing countries, the oral health promotion guidelines demonstrate ways to extend resources to meet a broader base of need. In all countries, oral health promotion can demonstrate the benefit of self-care and emphasize the consumer's responsibility for personal health. Dental associations enjoy a long history of promoting oral health, yet developing a coherent programme or realizing the results of these efforts can sometimes be disappointing or frustrating. The guide is organized around a recommended sequence of activities: policy formation and dissemination; planning group; information gathering; goal setting; strategic planning; implementation; and evaluation. This document presents guidelines, not recipes. Given the range of economic, social and health needs of the Fédération Dentaire Internationale member countries, a recipe would be inappropriate. These guidelines can be tailored to the needs of your association based on the oral health needs of your population. They can be used to determine new or modified policies, to assess long- and short-term goals, to monitor progress and to educate the membership. Case studies derived from actual experiences of dental associations as they planned and analysed their efforts to promote oral health are presented. This information is included to highlight different approaches as well as problems encountered. The case studies illustrate various parts of the planning implementation and evaluation process, while the text should serve as a comprehensive review of all these components.

Australia↗
PubMed1990

Leadership role of dental associations: oral health promotion.

'Promoting Oral Health: Guidelines for Dental Associations' is the product of Working Group 3 on Oral Health Promotion of the Commission on Oral Health, Research and Epidemiology of the FDI. This paper describes the guidelines document, its rationale and its potential utility. An organized planned sequence of activities, including policy formation and dissemination, planning group structure and function, information gathering, goal setting, strategic planning of objectives and interventions, implementation as well as monitoring and evaluation, are reviewed. Relevant to both industrialized and developing countries, these oral health promotion guidelines can be used to develop programmes to demonstrate the benefit of self-care and appropriate demand for dental services.

Health Planning↗
PubMed1989

Advances in the epidemiological study of oral-facial diseases.

Both demographic patterns and disease distribution are changing rapidly in the United States. These developments have led to the recognition that the epidemiology of many conditions is poorly understood, and that other research has thus been hindered. Four areas of epidemiological study were chosen for detailed analysis of how new technology will affect the conduct of future research. These areas, selected because information about them will be increasingly needed in an aging society, were periodontitis, temporomandibular disorders (TMD) and other orofacial pain, salivary gland disturbances, and health services research. The potential effect of new technology was examined in the short, intermediate, and long term. While the nature of epidemiological study is unlikely to change with the advent of new technology, the scope of potential studies will become broader. Advances in diagnostic techniques from elsewhere will permit far more precise diagnosis than is possible at present. Computer technology will permit an efficient system of epidemiological surveillance to provide current data on trends in tooth loss, caries, and periodontitis--data which will complement the results of national surveys. Analytical studies to produce hypotheses on the etiology of oral conditions, especially in such poorly-understood areas as chronic pain and TMD, will help direct clinical research in those areas.

Computers↗
PubMed1979

Intermembrane phospholipid transfer mediated by cell-free extracts of Rhodopseudomonas sphaeroides.

The transfer of phospholipids between two membrane substrates catalyzed by a soluble protein fraction from Rhodopseudomonas sphaeroides has been demonstrated. The assay employs purified intracytoplasmic membrane (ICM) vesicles derived from cells of R. sphaeroides grown on [3H]acetate as the phospholipid donor substrate and phosphatidylcholine (70%)/phosphatidylethanolamine (30%) unilamellar liposomes containing [14C]triolein, a nontransferable marker, as the acceptor substrate for transferred phospholipids. Incubation of these two membrane substrates with a 40 to 80% (NH4)2SO4 protein fraction from R. sphaeroides results in the transfer of tritium-labeled ICM phospholipids to the acceptor membrane substrate. Upon completion of the incubation period, the donor ICM vesicles are quantitatively separated from the acceptor liposomes by precipitation with antibody prepared against whole, purified ICM vesicles. Phospholipid transfer is linear with respect to time and protein concentration, is inhibited by trypsin and heat, and shows an absolute dependence upon the presence of acceptor liposomes and the 40 to 80% (NH4)2SO4 protein fraction. Control experiments indicate that no fusion of the donor and acceptor membrane occurs during the incubation period and that, following prolonged incubation there is no detectable degradation of the labeled lipid components. Preliminary data on the phospholipid specificity of the transfer reaction is also presented.

Biological Transport↗
PubMed1979

Psychosocial aspects of craniofacial disfigurement. A "State of the Art" assessment conducted by the Craniofacial Anomalies Program Branch, The National Institute of Dental Research.

The psychosocial sequelae of craniofacial disfigurement may have as great an impact on the patient as the strictly physical aspects of the problem. Very little systematic work has been focused directly on these effects. The following broad recommendations would constitute initial research steps in this field: Development of satisfactory measures of physical attractiveness and their use in studies to explore the role of craniofacial features in over-all physical attractiveness. The establishment of valid metrics for assessing the severity of craniofacial anomalies through the use of both physiologic and behavioral measures, thus constructing a broader definition of what constitutes a craniofacial handicap. Studies of the relationships among physiologic and behavioral variables using recently developed statistical techniques and computer methods to determine the psychosocial consequences of craniofacial disfigurement. Studies of the process through which persons with various types of malocclusion decide to seek and complete treatment. The studies would include the patients' demographic characteristics, self-perceptions, perceptions of them by others, and the complex patient-clinician interactions during the treatment programs.

Body Image↗
PubMed1979

Characterization of a site-specific restriction endonuclease from Rhodopseudomonas sphaeroides.

A type II restriction endonuclease, RshI, has been partially purified from photoheterotrophically grown Rhodopseudomonas sphaeroides strain 2.4.1. The enzyme preparation, after a single DE-52 column fractionation, is free of 5' exonuclease and phosphatase activities but contains a trace of 3' exonuclease activity. Based upon deoxyribonucleic acid (DNA) sequencing data in the vicinity of the enzyme-promoted cleavage of pBR322 DNA, we have concluded that RshI probably recognizes the palinodromic hexanucleotide sequence 5'-CGATCG-3' and cleaves between the T and C. lambda cI857 DNA contains three RshI sites, two of which lie in the replaceable region. The plasmid pBR322, which carries resistances to ampicillin and tetracycline, contains a single RshI site in the ampicillin resistance determinant. Insertion of DNA into the RshI site of pBR322 results in loss of ampicillin resistance but retention of tetracycline resistance, thereby providing a convenient screening procedure for recombinant plasmids.

Base Sequence↗
PubMed1977

Social sciences research: ethical and policy implications.

Ethical issues are raised about the conduct of social research in the dental field particularly with respect to the use of survey methodology and aggregated data. Problems associated with respondent identifiers, open-ended and probing questioning, privacy of subject-matter, community contamination and burden, group stereotyping, knowledge of law violations, mis-use of data banks, re-use of data, effects of disclosure, and referral for treatment are discussed. The natural and the contrived social experiments are reviewed as well as the issue of needed research on the effects of regulation on science and on the protection of privacy.

Behavioral Research↗
PubMed1976

Toward the formulation of sociodental indicators.

The bases for the construction of sociodental indicators is discussed in the paper, considering several available indexes of oral health status (dental caries, periodontal disease, malocclusion, oral hygiene, and other oral conditions) as well as measures of quality of services. Very little research exists relating any of the above measures to social indicators such as personal life-style or cultural and ecological factors. Such expansion would enable dental indicators to be useful for purposes of policy decisions. Combining any dental indicators or set of indicators with a potential global social health index is discussed in terms of potential problems obscuring dentistry's cost to society. Dentistry, in addition, is offered as a system in microcosm-one which can be useful for purposes of polishing methodology for the social health indicator movement.

Adult↗
PubMed1976

Transactions of an international conference. Worldwide concern: better dental care for more people. An international collaborative study. How the study was designed.

The study originated from the common need felt by the United States Public Health Service and the World Health Organization for objective information about various national dental care delivery systems and their effectiveness in the societies in which they were used. The relationships between consumers, providers and administrators within each system were emphasized rather than the comparison between systems since each operated within a specific biological and ecological environment. Six systems all of which had been in existence for at least twenty years were originally selected for study to encompass those dependent on a majority of government or private enterprise, use or non-use of auxiliaries, differeing systems of financing and of definition of target groups for receipt of services. The countries originally taking part were Australia, the Federal Republic of Germany, Japan, New Zealand, Norway and Bulgaria, though Bulgaria withdrew early in 1975.

Administrative Personnel↗