HICNet Medical News Digest Wed, 01 Jun 1994 Volume 07 : Issue 24 Today's Topics: Scientists Use "Fingerprints" to Track Periodontal Bacteria AIDS Daily News Summary +------------------------------------------------+ ! ! ! Health Info-Com Network ! ! Medical Newsletter ! +------------------------------------------------+ Editor: David Dodell, D.M.D. 10250 North 92nd Street, Suite 210, Scottsdale, Arizona 85258-4599 USA Telephone +1 (602) 860-1121 FAX +1 (602) 451-1165 Internet: mednews@stat.com Bitnet: ATW1H@ASUACAD Compilation Copyright 1994 by David Dodell, D.M.D. All rights Reserved. License is hereby granted to republish on electronic media for which no fees are charged, so long as the text of this copyright notice and license are attached intact to any and all republished portion or portions. The Health Info-Com Network Newsletter is distributed biweekly. Articles on a medical nature are welcomed. If you have an article, please contact the editor for information on how to submit it. If you are interested in joining the automated distribution system, please contact the editor. Associate Editors: E. Loren Buhle, Jr. Ph.D. Dept. of Radiation Oncology, Univ of Pennsylvania Tom Whalen, M.D., Robert Wood Johnson Medical School at Camden Douglas B. Hanson, Ph.D., Forsyth Dental Center, Boston, MA Lawrence Lee Miller, B.S. Biological Sciences, UCI Dr K C Lun, National University Hospital, Singapore W. Scott Erdley, MS, RN, SUNY@UB School of Nursing Subscription Requests = mednews@stat.com anonymous ftp = vm1.nodak.edu; directory HICNEWS FAX Delivery = Contact Editor for information ---------------------------------------------------------------------- Date: Wed, 01 Jun 94 22:09:25 MST From: mednews (HICNet Medical News) To: hicnews Subject: Scientists Use "Fingerprints" to Track Periodontal Bacteria Message-ID: Scientists Use "Fingerprints" to Track Periodontal Bacteria NIDR Research Digest, April 1994 Dental researchers can now identify the bacteria that cause periodontal diseases as precisely as fingerprint experts can identify people. NIDR grantee Dr. Joseph Zambon, at the State University of New York at Buffalo, recently reported on a technique that produces a "DNA fingerprint" so unique it can be used to track these disease-causing bacteria from one individual to another. "Identifying bacteria with this degree of precision is a technological advance that can provide important clues for preventing and treating gum disease," said Dr. Zambon. In addition to examining person-to- person transmission, the new fingerprinting technique can detect subtle differences in the bacterial distribution within an individual's mouth or among human populations scattered throughout the world. The technique can be also used to follow changes in bacterial populations during disease progression or in response to different types of treatment. "The applications are far-reaching," says Dr. Zambon. "We've just begun to apply this technique to study how to stop the infection by periodontal bacteria and how to eliminate existing infections." Identification of Source The procedure, developed independently at the California Institute of Biological Research and the E.M. duPont Company, was adapted by Dr. Zambon to track periodontal bacteria. The new technique holds great promise for unraveling the mystery of how these fragile bacteria, which are readily killed by oxygen in the air, initially gain access to the human mouth. In the past, studies attempting to answer questions about the source of an infection or person-to-person transmission of periodontal bacteria were hampered by the inability to distinguish between bacteria within the same species. These so-called 'strains' can look essentially the same, even when analyzed in great detail. In recent years, DNA fingerprinting technology has made it easier to discriminate between strains. The classic approach to DNA fingerprinting relies on enzymes that digest or break apart DNA. In this way the single bacterial chromosome, which is made up of two complimentary strands of DNA containing millions of nucleotide bases, is broken into many smaller fragments. The actual number and size of the DNA fragments depends on the structure of the bacterial chromosome. The DNA fragments can be separated on electrophoresis gels according to the molecular size of the DNA pieces. The fragments appear in the gel as a pattern of bands, referred to as the DNA fingerprint, which visually resembles the "bar codes" used by stores to identify merchandise. It is now known that each bacterial species can be separated into a finite number of strains based on differences in fingerprint patterns. However, the number of strains is highly variable among the different species of periodontal bacteria. For example, 29 different fingerprints have been reported for one species, Porphyromonas gingivalis. Only 3 fingerprints have been identified for another species, Actinobacillus actinomycetemcomitans (A.a.). Yet even with this kind of DNA fingerprinting it is difficult to do transmission studies on species like A.a., in which there are a number of patterns. Moreover, fingerprint patterns produced by DNA digestion can consist of several hundred bands, making it difficult to discriminate subtle existing differences. To get around these shortcomings, Dr. Zambon and his colleagues used a modified version called the arbitrarily primed polymerase chain reaction, or APPCR. This technique is based on the polymerase chain reaction (PCR), a method that is widely used to copy sections of DNA for identifying gene structure or matching tissue specimens. PCR uses two small, synthetic strips of DNA called primers to amplify a larger region of DNA. The primers bind to specific sites on opposing strands of the double-stranded DNA, and make millions of copies of the intervening stretch of DNA. The primers usually have specific nucleotide sequences that bind to previously identified segments of DNA. However, in the case of AP-PCR, no knowledge of the DNA sequence is required. A single primer, consisting of an arbitrary sequence of 10 or 12 bases, binds at random sites along the bacterial chromosome. The amplified segments vary in number and size depending on the unique structure of each bacterial chromosome. AP-PCR generates fewer bands and more unique patterns than does conventional fingerprinting, thereby increasing the ability to discriminate between similar strains. Although the work is still in the early stages, Dr. Zambon's group has successfully used AP-PCR to fingerprint several species of periodontal bacteria. In the case of A.a., 14 different fingerprints were produced from 20 isolates examined, compared to only three distinct genetic patterns from a large number of strains evaluated in studies using conventional fingerprinting. When AP-PCR was used to study A.a. from different families, it was observed that in 6 of 7 cases husband and wife harbored different strains. The children, however, carried strains identical to those found in one of the parents. These findings support the hypothesis that periodontal bacteria are transmitted from parent to child. Such information could eventually be useful in determining how and when a child is infected with A.a. or other periodontal bacteria, and what preventive measures may be effective. The study, funded by the NIDR and the Norwegian Research Council appeared in the October 1993 issue of the Journal of Clinical Microbiology and the January 1994 issue of the Journal of Periodontology. The investigators were Dr. Hans Preus of the Department of Periodontology, Dental Faculty, University of Oslo, Norway; and Drs. Violet Haraszthy, Joseph Roben Dunford and Robert Genco, representing the Departments of Oral Biology and Periodontology, School of Dental Medicine, State University of New York at Buffalo. ------------------------------ Date: Wed, 01 Jun 94 22:10:35 MST From: mednews (HICNet Medical News) To: hicnews Subject: AIDS Daily News Summary Message-ID: AIDS Daily Summary The Centers for Disease Control and Prevention (CDC) National AIDS Clearinghouse makes available the following information as a public service only. Providing this information does not constitute endorsement by the CDC, the CDC Clearinghouse, or any other organization. Reproduction of this text is encouraged; however, copies may not be sold, and the CDC Clearinghouse should be cited as the source of this information. Copyright 1994, Information, Inc., Bethesda, MD Topic in this issue - CDC Warns About Danger of AIDS in Home Care - New Test May Check for HIV in Newborn Babies - A Cytotoxic Response Against AIDS - AIDSLine: Is Some of My Pain Only in My Head? - A Novel Technique Fights AIDS Virus From Inside Cells - Scientists Recommend New AIDS Drug - New AIDS Treatment Acts on 'Resting' Cells--Researcher - Persistent Colonisation of Potable Water as a Source of Mycobacterium Avium Infection in AIDS "CDC Warns About Danger of AIDS in Home Care" Reuters (05/19/94) (Morgan, David) The Centers for Disease Control and Prevention yesterday reported two new cases of household HIV transmission, and issued a warning about the increasing potential for the spread of the virus in the home. The two household transmission cases, among eight that have occurred since 1986, may be the first in the country in which HIV infection clearly occurred through care-giving. In both cases, the virus was transmitted because standard precautions were not followed. One case involves the 5-year-old child of HIV-positive parents who researchers believe may have contracted the virus either through open sores on her mother's body, or by sharing a toothbrush at a time when the woman suffered from bleeding gums. Although the child initially tested negative for AIDS in 1990 and July 1993, HIV antibodies were present last December. More relevant to researchers is the other case--that of a 75-year-old woman caring for her HIV-infected adult son. The elderly woman, who had no other risk factors, tested positive for HIV in August 1991, a year after her son died. "She did provide nursing care to her son," said Dr. Harold Jaffe, director of the CDC's HIV/AIDS division, explaining that the woman was exposed to her son's urine, feces, and blood. "She wore gloves part of the time but not all the time." The CDC has issued a set of precautionary guidelines for people caring for HIV-infected loved ones at home. The recommendations include wearing protective gloves, careful handling and disposal of needles, and bandaging all open sores. Jaffe says the cases illustrate a problem posed by a lack of adequate instructions from medical professionals. "New Test May Check for HIV in Newborn Babies" Reuters (05/19/94) A new test that examines umbilical cord blood samples to detect cogenital infections in newborns may also effectively track whether HIV is transmitted from mother to baby, according to researchers. By testing for a protein called CD45, found in two forms in white "T" blood cells, in newborns and measuring the relative proportions of these two proteins, Drs. Colin Michie and David Harvey of the Royal Postgraduate Medical School were able to diagnose perinatally acquired infections such as chicken pox, cytomegalovirus, and toxoplasmosis in the infants. Michie and Harvey warn that these were the results of a preliminary study, and that a larger trial is needed to assess the suitability of the technique for determining whether HIV has been transmitted from a chronically infected mother to her baby. "A Cytotoxic Response Against AIDS" Lancet (04/30/94) Vol. 343, No. 8905, P. 1093 (Thompson, Clare) In examination of HIV pathology, one area of interest is the difference between short-term HIV survivors, who progress rapidly to full-blown AIDS, and long-term survivors, who remain healthy after a decade or more. There is also a subset of patients known as long-term non-progressors, who manage to stay healthy and maintain CD4 T-cell counts above 500. At the April meeting on Biotechnology against AIDS in Florence, several AIDS researchers discussed the possible role of CD8 lymphocytes in long-term survival. Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases described how the lymph-nodes of short-term survivors show a high level of viral burden and virus replication, and ultimately destruction of the lymph-node architecture, while the lymph-nodes of long-term non-progressors remain intact even after 10 years of infection. The differences suggest either that AIDS progression depends upon viral load, or that long-term non-progressors have some immune response that can clear the virus. "AIDSLine: Is Some of My Pain Only in My Head?" Advocate (05/03/94) No. 654, P. 34 (Cohan, Gary R.) HIV patients that experience aching, burning, numb, tingling, hypersensitive, or outright painful feelings in their hands and feet might think the pain is all in their head. Predominantly sensory neuropathy (PSN), however, is a nerve disorder that is actually rather common among people in the symptomatic, later stages of HIV infection. The condition, which develops in more than 30 percent of AIDS patients, often starts in the toes or fingertips and spreads proximally. Because PSN can make it painful to walk or use one's hands, early intervention is crucial. The patient's medication list should be reviewed to identify possible contributors to PSN, such as ddI, ddC, d4T, Dapsone, and isoniazid. Excess vitamin B6 or too much alcohol can also contribute to the problem. Mild neuropathy can be treated by simply taking ibuprofen (Advil or Motrin), while tricyclic antidepressants are more effective for more severe symptoms. Alternatives include topical capsaicin cream, certain antiseizure medicines, or a hear- rhythm drug called mexiletine hydrochloride. Because many of these drugs have adverse side effects, physicians should consider prescribing drugs to relieve severe discomfort. "A Novel Technique Fights AIDS Virus From Inside Cells" Philadelphia Inquirer (05/24/94) P. A2 (Collins, Huntly) Using a novel technique of gene therapy, researchers at Thomas Jefferson University have discovered how to virtually halt HIV's multiplication inside human cells. While antibodies usually prevent infection by binding to viruses outside of cells, this new method involves creating genetically-engineered antibodies that fight the disease inside infected cells. The Jefferson scientists targeted one of 10 known HIV genes called the Rev, which directs production of a protein that is essential for the virus to multiply in human cells. The researchers induced mice to produce the antibody to the Rev protein, then cloned the gene responsible for producing that antibody. They created a fragment of the gene by clipping out the two tips of the Y-shaped antibody and linking them together with another molecule. The synthetic gene fragment was then inserted into human cells, which were exposed to massive amounts of HIV. Although the cells became infected, viral reproduction was maintained at dramatically low levels, according to the researchers. Dr. Roger J. Pomerantz, head of the study, said he expects to seek federal approval this summer to test this novel approach in human subjects. If approved, a small safety trial could begin later this year. "Scientists Recommend New AIDS Drug" Baltimore Sun (05/21/94) P. 11A An advisory committee to the Food and Drug Administration last week recommended that the government approve a new drug to treat HIV, but with strong warnings that doctors still do not know enough about the medicine to say who should take it. The panel of scientists said that Stavudine, or d4T, probably has some benefit over the three existing AIDS drugs, but could not say precisely who would benefit, how safe the drug is, or whether the manufacturer is on the right track to answer these and other questions. The drug seems to help boost the immunity of HIV patients while creating fewer side effects than other drugs, according to Bristol-Myers Squibb. The company requested FDA approval of d4T for AIDS patients who cannot tolerate AZT, ddI, or ddC because of their serious side effects. The FDA has not said when it will make a decision regarding d4T. Related Story: Boston Globe (05/21) P. 10 "New AIDS Treatment Acts on 'Resting' Cells--Researcher" Reuters (05/21/94) A new HIV treatment unveiled this week is more promising than previous ones because it acts on inactive or "resting" cells, according to Dr. Jorge Vila, the doctor leading the researcher. "Antiviral drugs like AZT ... are not as efficient in humans as they are 'in vitro,'" Vila told local Argentine newspaper Pagina 12. "We believe that this is because the cells on which they are tested are active." In humans, 95 percent of the cells affected by HIV are "resting" ones, he said. A team of researchers headed by Vila reported last week that test-tube experiments with a combination of a new drug, DAH, and ddI, eliminated HIV from "resting" lymphocyte blood cells. The research may point toward an effective new treatment for the 14 million HIV-infected people around the globe. "Persistent Colonisation of Potable Water as a Source of Mycobacterium Avium Infection in AIDS" Lancet (05/07/94) Vol. 343, No. 8906, P. 1137 (Von Reyn, C.F.; Maslow, J.N.; Barber, T.W. et al.) The source of myobacterium avium infection in AIDS has not been identified; nor is it known whether most AIDS patients acquire the organism from recent infection or through reactivation of previous infection. As part of an epidemiological study, von Reyn et al. isolated colonies of M. avium from AIDS patients and from potable water to which they had been exposed. Of the isolates, which were analyzed with pulsed field gel electrophoresis, 29 of 39 patients were infected with one or more unique clinical strains of M. avium and seven patients were infected with three groups of common strains. Group 1 included three patients living in separate rural areas with no common exposures except for treatment at hospital A. The same strain was isolated repeatedly over a 41-month period from a recirculating hot water system at hospital A. Group 2 included two patients with no common exposure except for treatment at hospital B. The same strain was repeatedly isolated over two years from a recirculating hot water system at hospital B. Patients in both groups had numerous possible exposures to hospital hot water. Von Reyn et al. conclude that institutions may have hot water systems that are persistently colonized with a particular strain of M. avium. HIV patients who are exposed to such water sources can develop disseminated M. avium infection, they say. ------------------------------ End of HICNet Medical News Digest V07 Issue #24 *********************************************** --- Editor, HICNet Medical Newsletter Internet: david@stat.com FAX: +1 (602) 451-1165 Bitnet : ATW1H@ASUACAD