Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-03-29
2004-05-25
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C528S934000, C528S935000, C002S168000
Reexamination Certificate
active
06740719
ABSTRACT:
INDUSTRIAL APPLICABILITY
This invention relates to a process for reducing protein allergy caused by latex products, such as latex gloves and latex-containing devices used by the medical profession, which are made from the latex sap of the
Hevea brasilisensis
tree.
BACKGROUND OF THE INVENTION
It is well known that latex products, such as latex gloves, condoms, catheters and automobile tires made from the sap of the
Hevea brasilisensis
tree cause allergic reactions to some individuals who come into contact with such products. The allergic reaction is caused by the water-soluble proteins present in the sap of the tree and in the product made therewith.
In the late 1980s the United States Occupational Safety and Health Administration (OSHA) published
Bloodborne Pathogen Standards
requiring increased use of gloves to protect health care workers from exposure to the AIDS and hepatitis B viruses. Latex glove production substantially increased prior to and following the publication of such Standards. In 1991, the United States Food and Drug Administration (FDA) issued a latex alert regarding allergic reactions of patients and medical personnel who had come in contact with latex products. Among the latex products identified as potentially hazardous by the FDA were surgeon's gloves, latex exam gloves, latex condoms, barium enema retention rings and Foley catheters. The latex alert was issued after the number of annual cases regarding allergic reactions resulting from latex products increased from a few to 1,600. Of the three types of latex related diseases—dermatitis, cell mediated allergy and systemic allergy—which manifest themselves through different symptoms, cell mediated allergic response is a true allergic response, with reaction restricted to the area of contact between the glove and the skin when the glove is made from the sap of the
Hevea brasilisensis
tree. The reaction may include swelling and blistering and, after washing of the hands upon removal of the gloves, it takes from about 24 to 48 hours for the person's skin to return to normal. This allergy is caused by several water soluble proteins in latex sap.
Systemic latex allergy, the most serious of the latex-related diseases, is characterized by allergicrhinitis —asthma—and can escalate to anaphylaxis and death. This allergy is caused by several water soluble proteins in the latex sap from the
Hevea brasilisensis
tree present in products made from such sap, which proteins are dispersed in the air and are breathed in by people. Methods of measurement of airborne concentrations of latex antigen as well as latex antigen concentrations in products, such as gloves, in amount as low as 1 nanogram per cubic meter (ng/M
3
) are known. Several healthcare institutions have decided to adopt 10 ng/M
3
as a ceiling concentration or standard for personal exposure.
It is known that up to 100 percent of the water soluble protein can be removed from latex of the
Hevea brasilisensis
tree by subjecting the latex to several washings with water and to centrifugation, but with each washing the latex yield decreases, thus increasing the cost of the resulting purified product. Numerous attempts have been made by others to solve the problem of allergic reactions caused to certain people when they come into contact with rubber products made from the sap of the
Hevea brasilisensis
tree due to the proteins in the sap being present in such products.
U.S. Pat. No. 5,580,942 acknowledges the severe allergic reactions in hypersensitive people caused by the proteins present in the natural rubber latex obtained from
Hevea brasilisensis
trees. The patentee has a simple solution to the problem, namely, avoiding use of the latex from the
Hevea brasilisensis
in making latex products. Instead, the patentee uses latex extracted from the
Parthenium argontatum
(guayule) plant or the
Ficus elastica
plant, which plants have a different protein profile, whereby the proteins from the sap of these plants do not cause allergic reactions in hypersensitive humans.
A review of latex measurement proteins has been published (Beezhold D. H., Measurement of latex proteins by chemical and immunological methods, Procedings of Latex Protein Allergy: The Present Position. Amsterdam, December 1993).
Proteins have been isolated from rubber particles and from the B and C serum fractions of fresh non-ammoniated latex (NAL). When analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), distant protein bands are observed (Hasma,
J. Nat. Rubb. Res
., 1992, 7(2), 102-112; Arreguin, et al., Electrophoresis, 1988, 9, 323-326; Slater, et al.,
J. Allergy, Clin. Immunolo
., 1992, 89, 673-678.). Electrophoretic profiles of NAL reveals major proteins at 46, 29 and 14 kDa, and minor bands at 90, 55, 40, 36, 24, 20 and 18 kDa. Hevein (4 kDa) and hevamine (29 kDa) are two proteins in latex sera which have been cloned and sequenced (Lee et al.,
Biol Chem
., 1991, 256, 15944-15948; Jekel et al.,
Eur. J. Biochem
., 1991, 200, 123-130). In addition, rubber particles contain the tightly bound proteins prenyltransferase (38 kDa) and rubber elongation factor (14.5 kDa) which have also been sequenced (Dennis et al.,
Biol. Chem
., 1989, 264, 18618-26; Light et al.,
J. Biol. Chem
., 1989 264, 18589-97).
Ammonification of latex alters the proteins. Storage of latex in ammonia alters the electrophoretic profiles of proteins such that SDS-PAGE profile changes from distinct bands to a smear of polypeptides with an increase in high molecular weight material (Breezhold et al.,
Arch. Surg
., 1992, 127, 1354-1357). Many, but not all, of the changes that occur are due to hydrolysis of the proteins. Since NAL serum proteins migrate primarily below 46 kDa, the appearance of high molecular weight polypeptides suggests that ammonification (and/or other compounding ingredients) induce a type of polymerization of the latex proteins that produces the larger polypeptides. This process may contribute to the allergenicity of the latex proteins. In addition, ammonification also extracts some of the rubber bound proteins (primarily rubber elongation factor) making them soluble proteins and thus potential allergens (Hasma,
J. Nat. Rubb. Res
., 1992, 7(2), 102-112).
Much of the protein in latex is not tightly bound to the rubber, but is “water soluble” and readily leaches out of the latex. In order to measure latex proteins it is important to understand the parameters which influence extractability. It has been shown that water soluble proteins are readily extractable, however, complete extraction may take up to 18 hours or more (Dalrymple et al.,
Rubb. Devel
., 1992, 45, 51-60; Hashim,
International Rubber Technology Conference
, Kuala Lumpur, Malaysia, June 1993; Yeang et al.,
International Rubber Technology Conference
, Kuala Lumpur, Malaysia, June 1993). The volume, pH, and composition of extraction buffer are also important factors.
A majority of the latex proteins have an acidic pH between 4.0 and 6.5 (Chambeyron et al.,
Allergy
, 1992, 90, 230-235) that increases their solubility in basic buffers and helps explain the observation that more protein is extracted in higher pH buffers. Latex proteins are drawn to the surface of the latex during drying. The surface proteins can be collected directly from the surface by dry swabbing (Dalrymple et al.,
Rubb. Devel
., 1992, 45, 51-60). By analyzing proteins obtained from dry swabbing rubber films, a unique group of surface proteins which are nearly insoluble in water and have limited solubility in carbonate buffer was observed. These proteins migrate in SDS gels with a relative molecular mass of between 60 and 70 kDa. The proteins are remarkable in that they can be identified by their ability to non-specifically bind IgM from human serum. Furthermore, the IgM binding proteins (IgMbp) can activate the serum complement system and thereby have the potential to cause anaphylactoid reactions. Because these proteins are insoluble they are easily overlooked but must be considered as a potential source of allergens.
Nutter Nathan M.
Smith Gambrell & Russell
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