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MUTATED GENE LINKED TO CHERUBISM
N E W S
STAPHYLOCOCCUS AUREUS RESISTANT TO POWERFUL NEW ANTIBIOTIC
A patient in Boston was the first to become infected with a strain of Staphylococcus aureus bacteria resistant to the latest generation of antibiotics, according to a letter in the July 21 issue of The Lancet. The U.S. Food and Drug Administration approved the powerful antibiotic linezolid in early 2000. It has become the last line of defense against infections by various grampositive bacteria, including methicillin-resistant S. aureus, or MRSA, and vancomycinresistant enterococci, or VRE. Linezolid resistance in VRE was reported in April, but this was the first reported incidence of resistance in S. aureus. In The Lancet letter, coauthor Mary Jane Ferraro, Ph.D., reported that an MRSA isolate resistant to linezolid had been recovered from an 85-yearold man treated for dialysisassociated peritonitis with this antibiotic. The bacterium also was resistant to methicillin. However, the patient could be treated with more commonly used antibiotics, which usually is not possible. This is the only reported case of linezolid-resistant S. aureus so far, according to The Lancet letter. “Methicillin-resistant strains account for more than onefourth of S. aureus bloodstream isolates and most of the nosocomial S. aureus infections in intensive care patients in the United States,” said the authors at the conclusion of their letter. “The emergence of resistance to linezolid in MRSA is an unwelcome development.”
MUTATED GENE LINKED TO CHERUBISM
The discovery of a genetic mutation responsible for the childhood bone disorder cherubism was reported by researchers at the Harvard School of Dental Medicine and The Forsyth Institute in the June 1 issue of Nature Genetics. In its mild forms, cherubism causes children to develop chubby cheeks and upward-looking eyes like those of cherubs in religious artwork. In its severe forms, cherubism can lead to excessive degradation of the jawbone. The bone tissue is replaced by soft-tissue masses, which can cause facial swelling that intrudes into the eye socket and forces the eyeballs to tilt upwards. People who have cherubism also experience tooth malformations and loss, as well as chronic inflammation of lymph nodes. Many have difficulty chewing because of reduced jaw movement. This genetic mutation primarily affects young children starting at about age three or four years, when the primary teeth normally begin to fall out. The disorder usually diminishes after puberty, and children who had a mild form generally do not exhibit external manifestations as adults. Researchers discovered the mutation when they screened 25 genes located on chromosome 4p; the genes were obtained from the DNA of affected families in several countries. Researchers compared the genes from affected people with those of unaffected people. Yasuyoshi Ueki, M.D., Ph.D., discovered a mutation in the SH3BP2 gene in affected people.
The gene codes for a protein involved in the signaling mechanism of certain cells. Because cherubism involves both bone degradation and the growth of tumorlike cells, researchers hypothesized that the mutant protein functions differently in different kinds of cells. For example, the mutant protein may activate osteoblasts that degrade the bone, while also activating osteoblasts or osteoblast precursors that normally build bone. These atypical osteoblasts proliferate, fill in cavities created by degraded bone and continue to grow as a fibrous tissue mass. This discovery is “very exciting,” because it could lead to potential therapies or prenatal diagnosis for the disorder, said researcher Bjorn Olsen, M.D., Ph.D. CORRECTION
The Dental Product Spotlight in August JADA, “Whitening Toothpastes,” contained an error. The copy in the Seal of Acceptance box should have read as follows: “(Product name) has been shown to be an effective decay-preventive dentifrice that can be of significant value when used as directed in a conscientiously applied program of oral hygiene and regular professional care. Council on Scientific Affairs, American Dental Association.” Compiled by Amy E. Lund, editorial coordinator.
MEETINGS
dThe Greater St. Louis Dental Society will hold its MidContinent Dental Congress Sept. 13-15. For more information, contact Beverly Shabansky
JADA, Vol. 132, September 2001 Copyright ©1998-2001 American Dental Association. All rights reserved.
1217
STAPHYLOCOCCUS AUREUS RESISTANT TO POWERFUL NEW ANTIBIOTIC
A patient in Boston was the first to become infected with a strain of Staphylococcus aureus bacteria resistant to the latest generation of antibiotics, according to a letter in the July 21 issue of The Lancet. The U.S. Food and Drug Administration approved the powerful antibiotic linezolid in early 2000. It has become the last line of defense against infections by various grampositive bacteria, including methicillin-resistant S. aureus, or MRSA, and vancomycinresistant enterococci, or VRE. Linezolid resistance in VRE was reported in April, but this was the first reported incidence of resistance in S. aureus. In The Lancet letter, coauthor Mary Jane Ferraro, Ph.D., reported that an MRSA isolate resistant to linezolid had been recovered from an 85-yearold man treated for dialysisassociated peritonitis with this antibiotic. The bacterium also was resistant to methicillin. However, the patient could be treated with more commonly used antibiotics, which usually is not possible. This is the only reported case of linezolid-resistant S. aureus so far, according to The Lancet letter. “Methicillin-resistant strains account for more than onefourth of S. aureus bloodstream isolates and most of the nosocomial S. aureus infections in intensive care patients in the United States,” said the authors at the conclusion of their letter. “The emergence of resistance to linezolid in MRSA is an unwelcome development.”
MUTATED GENE LINKED TO CHERUBISM
The discovery of a genetic mutation responsible for the childhood bone disorder cherubism was reported by researchers at the Harvard School of Dental Medicine and The Forsyth Institute in the June 1 issue of Nature Genetics. In its mild forms, cherubism causes children to develop chubby cheeks and upward-looking eyes like those of cherubs in religious artwork. In its severe forms, cherubism can lead to excessive degradation of the jawbone. The bone tissue is replaced by soft-tissue masses, which can cause facial swelling that intrudes into the eye socket and forces the eyeballs to tilt upwards. People who have cherubism also experience tooth malformations and loss, as well as chronic inflammation of lymph nodes. Many have difficulty chewing because of reduced jaw movement. This genetic mutation primarily affects young children starting at about age three or four years, when the primary teeth normally begin to fall out. The disorder usually diminishes after puberty, and children who had a mild form generally do not exhibit external manifestations as adults. Researchers discovered the mutation when they screened 25 genes located on chromosome 4p; the genes were obtained from the DNA of affected families in several countries. Researchers compared the genes from affected people with those of unaffected people. Yasuyoshi Ueki, M.D., Ph.D., discovered a mutation in the SH3BP2 gene in affected people.
The gene codes for a protein involved in the signaling mechanism of certain cells. Because cherubism involves both bone degradation and the growth of tumorlike cells, researchers hypothesized that the mutant protein functions differently in different kinds of cells. For example, the mutant protein may activate osteoblasts that degrade the bone, while also activating osteoblasts or osteoblast precursors that normally build bone. These atypical osteoblasts proliferate, fill in cavities created by degraded bone and continue to grow as a fibrous tissue mass. This discovery is “very exciting,” because it could lead to potential therapies or prenatal diagnosis for the disorder, said researcher Bjorn Olsen, M.D., Ph.D. CORRECTION
The Dental Product Spotlight in August JADA, “Whitening Toothpastes,” contained an error. The copy in the Seal of Acceptance box should have read as follows: “(Product name) has been shown to be an effective decay-preventive dentifrice that can be of significant value when used as directed in a conscientiously applied program of oral hygiene and regular professional care. Council on Scientific Affairs, American Dental Association.” Compiled by Amy E. Lund, editorial coordinator.
MEETINGS
dThe Greater St. Louis Dental Society will hold its MidContinent Dental Congress Sept. 13-15. For more information, contact Beverly Shabansky
JADA, Vol. 132, September 2001 Copyright ©1998-2001 American Dental Association. All rights reserved.
1217