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Transforming growth factor beta-1 gene polymorphism and bone mineral density in japanese adolescents
BRIEF OBSERVATIONS
Transforming Growth Factor Beta-1 Gene Polymorphism and Bone Mineral Density in Japanese Adolescents Yoshiji Yamada, MD, Takayuki Hosoi, MD, Fukashi Makimoto, MD, Hiroyuki Tanaka, MD, Yoshiki Seino, MD, Kyoji Ikeda, MD
O
steoporosis has a strong genetic component (1). Among the genes that may be associated with bone mineral density are those encoding the vitamin D (2,3) and estrogen (4) receptors, collagen Ia1 (5,6), and apolipoprotein E (7). Transforming growth factor b1 (TGF-b1), which is abundantly stored in bone, is an important regulator of skeletal development and homeostasis. TGF-b1 has been shown to stimulate the proliferation and differentiation of osteoblasts, as well as their production of matrix, and to enhance bone formation in vivo (8). In addition, TGF-b1 has been implicated as a local mediator of the skeletal effects of estrogen, such as the estrogen-induced apoptosis of osteoclasts, thereby protecting against excessive bone resorption (9). We have previously demonstrated that a T 3 C polymorphism at nucleotide 29 of the signal sequence of the TGF-b1 gene, which results in the replacement of a leucine at amino acid 10 by a proline residue, is associated with bone mineral density at the lumbar spine in postmenopausal Japanese women (10). Moreover, we found that the T allele represents an independent risk factor for the development of osteoporosis, in that individuals with the T allele are 15 to 33 times more susceptible to osteoporosis than those who are homozygous for the C allele (10). The risk of developing involutional osteoporosis is thought to depend on the peak bone mass achieved in early adulthood and the rate of bone loss occurring after 45 to 50 years of age (11). It is not known, however, if the T 3 C polymorphism of the TGF-b1 gene affects bone mass by increasing peak bone mass or by reducing the rate of bone loss. To distinguish between these possibilities, we assessed TGF-b1 genotype and bone mineral density in Japanese adolescents.
METHODS The study sample consisted of 356 healthy high school students (167 girls and 92 boys from Tamano City, q1999 by Excerpta Medica, Inc. All rights reserved.
Okayama Prefecture, and 97 girls from Hakodate City, Hokkaido). None of the subjects had any serious disease or had taken any drug known to affect bone or calcium metabolism. Informed consent was obtained from all subjects. Bone mineral density and content were measured at the distal third of the radius by dual-energy x-ray absorptiometry using a DCS-600 instrument (Aloka, Tokyo, Japan). Bone mineral density was adjusted for difference in body mass index, separately in girls and boys. The TGF-b1 genotype of each subject was determined by an allele-specific polymerase chain reaction assay (10). Data were compared among TGF-b1 genotypes by one-way analysis of variance and Scheffe’s multiple range test. The chi-square test was used to identify significant departures from Hardy-Weinberg equilibrium. A P value ,0.05 was considered statistically significant.
RESULTS The genotype distributions in each city were in HardyWeinberg equilibrium, suggesting that the subjects in both cities were from a homogeneous genetic background (Table 1). We observed a significant association between TGF-b1 genotype and bone mineral density, which was related to the number of C alleles. Both girls and boys with the CC genotype had 5% to 6% greater bone mineral density than those with the TT genotype. We also detected a significant association between TGF-b1 genotype and bone mineral content. There was a trend toward greater body weight and body mass index as a function of the number of C alleles. When bone mineral density was adjusted for differences in body mass index, there were significant differences between girls with the CC and the TT genotypes and between boys with the CC and the TT genotypes in Tamano City. (There was a trend among girls from Hakodate City, although statistical significance was not reached.) We found no associations between TGF-b1 genotype and age, height, or years after menarche.
DISCUSSION There are several other polymorphisms in the TGF-b1 gene (12–14). A one-base deletion in intron 4 (7138delC) of the TGF-b1 gene has been shown to be more frequent in subjects with osteoporosis than in normal controls (14). However, it is unlikely that there is linkage disequilibrium between the T29 3 C polymorphism and 713-8delC (10). The Leu 3 Pro polymorphism at amino acid 10 of the TGF-b1 is located in the 29-residue signal peptide se0002-9343/99/$–see front matter 477 PII S0002-9343(99)00043-1
Brief Observations
TC 50 (51%) 15.9 6 0.3 156 6 5 52.4 6 8.8 21.0 6 3.3 3.4 6 0.8 0.68 6 0.08 0.61 6 0.05 2 (22, 6) 0.61 6 0.05 2 (22, 5) TT 29 (30%) 16.0 6 0.8 156 6 5 51.2 6 9.4 20.4 6 4.0 3.1 6 1.4 0.64 6 0.06‡ 0.60 6 0.04 — 0.60 6 0.05 —
Hakodate City, Girls (n 5 97)
CC 18 (19%) 15.8 6 0.3 155 6 5 55.8 6 7.6 22.9 6 3.7 3.6 6 1.1 0.72 6 0.05 0.63 6 0.03* 6 (2, 10) 0.62 6 0.03 3 (21, 8)
quence, which functions to translocate newly synthesized protein across the membrane of the endoplasmic reticulum. Because the serum concentration of TGF-b1 correlates with the number of C alleles (ie, with the presence of a proline residue at amino acid 10), it is possible that this polymorphism may affect the secretion of TGF-b1 (10). Our results suggest that increased skeletal growth during puberty may be associated with the C allele of the TGF-b1 gene and that TGF-b1 genotype may be one of the genetic determinants of bone mass in both women and men.
478
CC 44 (26%) 16.4 6 1.0 159 6 5 54.1 6 7.2 21.5 6 2.9 4.1 6 1.3 0.74 6 0.16* 0.65 6 0.05§ 5 (2, 9) 0.65 6 0.05* 4 (1, 7) TC 71 (43%) 16.8 6 1.1 158 6 5 53.4 6 7.4 21.3 6 2.5 4.6 6 1.5 0.70 6 0.09 0.63 6 0.05 2 (21, 5) 0.63 6 0.05 1 (22, 4) Genotype No. of subjects (%) Age (years) Height (cm) Body weight (kg) Body mass index (kg/m2) Years after menarche Bone mineral content (g/cm) Bone mineral density (g/cm2) Bone mineral density (% difference)i Adjusted bone mineral density (g/cm2)¶ Adjusted bone mineral density (% difference)i
TT 52 (31%) 16.9 6 0.9 158 6 6 52.2 6 6.3 20.9 6 2.2 4.8 6 1.5 0.69 6 0.08 0.62 6 0.05 — 0.62 6 0.05 —
Girls (n 5 167)
April 1999
THE AMERICAN JOURNAL OF MEDICINEt
* P 5 0.04 vs TT; † P 5 0.005 vs TT, P 5 0.01 vs TC; ‡ P 5 0.0004 vs CC, P 5 0.04 vs TC; § P 5 0.02 vs TT. i Mean difference (95% confidence interval) as percent greater than TT genotype. ¶ Adjusted for body mass index.
TC 43 (47%) 16.9 6 0.9 171 6 5 62.3 6 5.9 21.3 6 1.5 — 0.91 6 0.11 0.72 6 0.05 2 (21, 4) 0.73 6 0.05 2 (21, 5) TT 35 (38%) 16.8 6 1.0 171 6 6 63.1 6 5.0 21.5 6 1.1 — 0.89 6 0.10 0.71 6 0.05 — 0.71 6 0.05 —
Boys (n 5 92) Tamano City (n 5 259)
Table 1. Characteristics of the Subjects (mean 6 SD) According to Transforming Growth Factor (TGF)-b1 Genotype
CC 14 (15%) 16.7 6 0.9 173 6 6 65.7 6 7.5 21.9 6 1.9 — 1.01 6 0.13† 0.75 6 0.04§ 6 (2, 10) 0.75 6 0.04§ 5 (2, 9)
REFERENCES
Volume 106
1. Pocock NA, Eisman JA, Hopper JL, et al. Genetic determinants of bone mass in adults: a twin study. J Clin Invest. 1987;80:706 –710. 2. Morrison NA, Qi JC, Tokita A, et al. Prediction of bone density from vitamin D receptor alleles. Nature. 1994;367:284 –287. 3. Harris SS, Eccleshall TR, Gross C, et al. The vitamin D receptor start codon polymorphism (Fok I) and bone mineral density in premenopausal American black and white women. J Bone Miner Res. 1997;12:1043–1048. 4. Kobayashi S, Inoue S, Hosoi T, et al. Association of bone mineral density with polymorphism of the estrogen receptor gene. J Bone Miner Res. 1996;11:306 –311. 5. Grant SFA, Reid DM, Blake G, et al. Reduced bone density and osteoporosis associated with a polymorphic Sp1 binding site in the collagen type Ia1 gene. Nature Genet. 1996;14:203–205. 6. Uitterlinden AG, Burger H, Huang Q, et al. Relation of alleles of the collagen type Ia1 gene to bone density and the risk of osteoporotic fractures in postmenopausal women. NEJM. 1998;338:1016 –1021. 7. Shiraki M, Shiraki Y, Aoki C, et al. Association of bone mineral density with apolipoprotein E phenotype. J Bone Miner Res. 1997; 12:1438 –1445. 8. Bonewald LF. Transforming growth factor-b. In: Bilezikian JP, Raisz LG, Rodan GA, eds. Principles of Bone Biology. San Diego: Academic Press, 1996:647– 659. 9. Hughes DE, Dai A, Tiffee JC, et al. Estrogen promotes apoptosis of murine osteoclasts mediated by TGF-b. Nature Med. 1996;2:1132– 1136. 10. Yamada Y, Miyauchi A, Goto J, et al. Association of a polymorphism of the transforming growth factor-b1 gene with genetic susceptibility to osteoporosis in Japanese women. J Bone Miner Res. 1998;13:1569 –1576. 11. Riggs BL, Khosla S, Melton LJ III. A unitary model for involutional osteoporosis: estrogen deficiency caused both type I and type II osteoporosis in postmenopausal women and contributes to bone loss in aging men. J Bone Miner Res. 1998;13:763–773. 12. Derynck R, Rhee L, Chen EY, van Tilburg A. Intron-exon structure of the human transforming growth factor-b precursor gene. Nucleic Acids Res. 1987;15:3188 –3189. 13. Cambien F, Ricard S, Troesch A, et al. Polymorphisms of the transforming growth factor-b1 gene in relation to myocardial infarction and blood pressure. Hypertension. 1996;28:881– 887. 14. Langdahl BL, Knudsen JY, Jensen HK, Gregersen N, Eriksen EF. A sequence variation: 713-8delC in the transforming growth factorbeta 1 gene has higher prevalence in osteoporotic women than in normal women and is associated with very low bone mass in osteoporotic women and increased bone turnover in both osteoporotic and normal women. Bone. 1997;20:289 –294. From the Department of Geriatric Research (YY, KI), National Institute for Longevity Sciences, Obu; Endocrinology Section (TH), Tokyo Metropolitan Geriatric Hospital, Tokyo; Department of Obstetrics and Gynecol-
Brief Observations ogy (FM), Akiyama Memorial Hospital, Hakodate; and Department of Pediatrics (HT, YS), Okayama University Medical School, Okayama, Japan. Supported in part by a Health Sciences Research Grant for Research on Human Genome and Gene Therapy (to KI) and by a Research Grant for Longevity Sciences (to YY) from the Ministry of Health and Welfare of Japan. Requests for reprints should be addressed to Yoshiji Yamada, MD, Department of Geriatric Research, National Institute for Longevity Sciences, 36-3 Gengo, Morioka, Obu, Aichi 474-8522, Japan. Manuscript submitted September 8, 1998, and accepted in revised form December 8, 1998.
Increased Risk of Exposure to Hepatitis B Infection among Butchers Sharing Knives Dror Mevorach, MD, Mayer Brezis, MD, Fiamenta Ben Yishai, MD, Tomi Sadeh, VMD, Daniel Shouval, MD, Rami Eliakim, MD
T
he risk of hepatitis B virus infection is increased by exposure to blood and blood products. Whereas hepatitis B has long been recognized as an occupational disease in health-care workers (1), other occupations have not been as well studied. Identification of these groups may shed light on the modes of viral transmission and suggest workers who may benefit from targeted vaccination. We recently reported an outbreak of hepatitis B in a butchery in Jerusalem (2). Similar observations have been reported from Australia (3) and Germany (4). To test the hypothesis that butchers are at increased risk of hepatitis B infection, we conducted a cross sectional survey among workers of slaughterhouses and butcheries.
MATERIALS AND METHODS The study sample consisted of 124 workers in three slaughterhouses and 10 butcheries in the Jerusalem district. All subjects answered a questionnaire that included ethnic origin, number of years worked, past or present use of knives at work, frequency of hand cuts, past medical history, and other risk factors for hepatitis B. Workers were divided into butchers who used knives in their routine work and nonbutchers (controls) working in the same business without using knives. Blood samples were collected and tested for antibodies to hepatitis B core antigen (anti-HBc) and to hepatitis C virus (anti-HCV), using a second-generation enzymelinked immunosorbent assay (ELISA; Abbott Laboratories, Chicago, Illinois). Serum samples found positive for
anti-HBc were further tested for hepatitis B surface antigen (HBsAg) and antibody (anti-HBs). Samples that were positive for HBsAg were also tested for e antigen (HBeAg) and hepatitis B viral DNA. Hepatitis B antigens and antibodies were tested by ELISA (Abbott Laboratories, Chicago, Illinois); DNA was assayed by molecular hybridization (5). The chi-square test and Fisher’s exact test were used to compare proportions, and Student’s t test was used to compare continuous variables. A logistic regression model was used to assess the independent effect of occupation, religious background (Muslim, Jewish), and age on the prevalence of exposure to hepatitis B virus. Age was entered as a continuous variable or as a dichotomous variable ($40 years, ,40 years).
RESULTS One hundred twenty-three subjects were included in the study (Table 1). All were men except for one woman in the butcher group. One employee was excluded because of a past blood transfusion. Butchers were younger (P ,0.004) and somewhat more likely to be Moslem (P 5 0.08). However, in a multivariate logistic regression model, only occupation was significantly associated with the prevalence of exposure to hepatitis B virus (odds ratio 5 2.8; 95% confidence interval 1.1 to 7.1). This result was consistent whether age was entered as a continuous or dichotomous variable. At work sites that had no HBsAg-positive workers, only 26% (14 of 54) of the butchers had evidence of hepatitis B infection. However, at the two sites that each had a single HBsAg-positive worker, 57% (16 of 28) of butchers had hepatitis B exposure (P ,0.02). Furthermore, at the butchery with a highly infective HBsAg-positive worker (with positive HBeAg and hepatitis B viral DNA), 4 of the 5 workers had evidence of hepatitis B infection. Table 1. Characteristics of the Butchers and Other Employees (controls)*
Age, years (mean 6 SD) Muslim† More than 1 hand cut per month More than 1 hand cut per week Hepatitis B core antibody positive Antibodies to hepatitis C
Butchers (n 5 82), Number (percent)
Controls (n 5 41), Number (percent)
36 6 5 55 (67) 72 (88) 51 (62) 30 (37) 0
33 6 5 22 (56) 1 (2) 0 7 (17) 0
* Mean age (P ,0.004), reported hand cuts (P ,0.001), and the prevalence of infection with hepatitis B virus (P ,0.05) were significantly different in butchers and controls. † All other subjects were Jewish. April 1999
THE AMERICAN JOURNAL OF MEDICINEt
Volume 106 479
Transforming Growth Factor Beta-1 Gene Polymorphism and Bone Mineral Density in Japanese Adolescents Yoshiji Yamada, MD, Takayuki Hosoi, MD, Fukashi Makimoto, MD, Hiroyuki Tanaka, MD, Yoshiki Seino, MD, Kyoji Ikeda, MD
O
steoporosis has a strong genetic component (1). Among the genes that may be associated with bone mineral density are those encoding the vitamin D (2,3) and estrogen (4) receptors, collagen Ia1 (5,6), and apolipoprotein E (7). Transforming growth factor b1 (TGF-b1), which is abundantly stored in bone, is an important regulator of skeletal development and homeostasis. TGF-b1 has been shown to stimulate the proliferation and differentiation of osteoblasts, as well as their production of matrix, and to enhance bone formation in vivo (8). In addition, TGF-b1 has been implicated as a local mediator of the skeletal effects of estrogen, such as the estrogen-induced apoptosis of osteoclasts, thereby protecting against excessive bone resorption (9). We have previously demonstrated that a T 3 C polymorphism at nucleotide 29 of the signal sequence of the TGF-b1 gene, which results in the replacement of a leucine at amino acid 10 by a proline residue, is associated with bone mineral density at the lumbar spine in postmenopausal Japanese women (10). Moreover, we found that the T allele represents an independent risk factor for the development of osteoporosis, in that individuals with the T allele are 15 to 33 times more susceptible to osteoporosis than those who are homozygous for the C allele (10). The risk of developing involutional osteoporosis is thought to depend on the peak bone mass achieved in early adulthood and the rate of bone loss occurring after 45 to 50 years of age (11). It is not known, however, if the T 3 C polymorphism of the TGF-b1 gene affects bone mass by increasing peak bone mass or by reducing the rate of bone loss. To distinguish between these possibilities, we assessed TGF-b1 genotype and bone mineral density in Japanese adolescents.
METHODS The study sample consisted of 356 healthy high school students (167 girls and 92 boys from Tamano City, q1999 by Excerpta Medica, Inc. All rights reserved.
Okayama Prefecture, and 97 girls from Hakodate City, Hokkaido). None of the subjects had any serious disease or had taken any drug known to affect bone or calcium metabolism. Informed consent was obtained from all subjects. Bone mineral density and content were measured at the distal third of the radius by dual-energy x-ray absorptiometry using a DCS-600 instrument (Aloka, Tokyo, Japan). Bone mineral density was adjusted for difference in body mass index, separately in girls and boys. The TGF-b1 genotype of each subject was determined by an allele-specific polymerase chain reaction assay (10). Data were compared among TGF-b1 genotypes by one-way analysis of variance and Scheffe’s multiple range test. The chi-square test was used to identify significant departures from Hardy-Weinberg equilibrium. A P value ,0.05 was considered statistically significant.
RESULTS The genotype distributions in each city were in HardyWeinberg equilibrium, suggesting that the subjects in both cities were from a homogeneous genetic background (Table 1). We observed a significant association between TGF-b1 genotype and bone mineral density, which was related to the number of C alleles. Both girls and boys with the CC genotype had 5% to 6% greater bone mineral density than those with the TT genotype. We also detected a significant association between TGF-b1 genotype and bone mineral content. There was a trend toward greater body weight and body mass index as a function of the number of C alleles. When bone mineral density was adjusted for differences in body mass index, there were significant differences between girls with the CC and the TT genotypes and between boys with the CC and the TT genotypes in Tamano City. (There was a trend among girls from Hakodate City, although statistical significance was not reached.) We found no associations between TGF-b1 genotype and age, height, or years after menarche.
DISCUSSION There are several other polymorphisms in the TGF-b1 gene (12–14). A one-base deletion in intron 4 (7138delC) of the TGF-b1 gene has been shown to be more frequent in subjects with osteoporosis than in normal controls (14). However, it is unlikely that there is linkage disequilibrium between the T29 3 C polymorphism and 713-8delC (10). The Leu 3 Pro polymorphism at amino acid 10 of the TGF-b1 is located in the 29-residue signal peptide se0002-9343/99/$–see front matter 477 PII S0002-9343(99)00043-1
Brief Observations
TC 50 (51%) 15.9 6 0.3 156 6 5 52.4 6 8.8 21.0 6 3.3 3.4 6 0.8 0.68 6 0.08 0.61 6 0.05 2 (22, 6) 0.61 6 0.05 2 (22, 5) TT 29 (30%) 16.0 6 0.8 156 6 5 51.2 6 9.4 20.4 6 4.0 3.1 6 1.4 0.64 6 0.06‡ 0.60 6 0.04 — 0.60 6 0.05 —
Hakodate City, Girls (n 5 97)
CC 18 (19%) 15.8 6 0.3 155 6 5 55.8 6 7.6 22.9 6 3.7 3.6 6 1.1 0.72 6 0.05 0.63 6 0.03* 6 (2, 10) 0.62 6 0.03 3 (21, 8)
quence, which functions to translocate newly synthesized protein across the membrane of the endoplasmic reticulum. Because the serum concentration of TGF-b1 correlates with the number of C alleles (ie, with the presence of a proline residue at amino acid 10), it is possible that this polymorphism may affect the secretion of TGF-b1 (10). Our results suggest that increased skeletal growth during puberty may be associated with the C allele of the TGF-b1 gene and that TGF-b1 genotype may be one of the genetic determinants of bone mass in both women and men.
478
CC 44 (26%) 16.4 6 1.0 159 6 5 54.1 6 7.2 21.5 6 2.9 4.1 6 1.3 0.74 6 0.16* 0.65 6 0.05§ 5 (2, 9) 0.65 6 0.05* 4 (1, 7) TC 71 (43%) 16.8 6 1.1 158 6 5 53.4 6 7.4 21.3 6 2.5 4.6 6 1.5 0.70 6 0.09 0.63 6 0.05 2 (21, 5) 0.63 6 0.05 1 (22, 4) Genotype No. of subjects (%) Age (years) Height (cm) Body weight (kg) Body mass index (kg/m2) Years after menarche Bone mineral content (g/cm) Bone mineral density (g/cm2) Bone mineral density (% difference)i Adjusted bone mineral density (g/cm2)¶ Adjusted bone mineral density (% difference)i
TT 52 (31%) 16.9 6 0.9 158 6 6 52.2 6 6.3 20.9 6 2.2 4.8 6 1.5 0.69 6 0.08 0.62 6 0.05 — 0.62 6 0.05 —
Girls (n 5 167)
April 1999
THE AMERICAN JOURNAL OF MEDICINEt
* P 5 0.04 vs TT; † P 5 0.005 vs TT, P 5 0.01 vs TC; ‡ P 5 0.0004 vs CC, P 5 0.04 vs TC; § P 5 0.02 vs TT. i Mean difference (95% confidence interval) as percent greater than TT genotype. ¶ Adjusted for body mass index.
TC 43 (47%) 16.9 6 0.9 171 6 5 62.3 6 5.9 21.3 6 1.5 — 0.91 6 0.11 0.72 6 0.05 2 (21, 4) 0.73 6 0.05 2 (21, 5) TT 35 (38%) 16.8 6 1.0 171 6 6 63.1 6 5.0 21.5 6 1.1 — 0.89 6 0.10 0.71 6 0.05 — 0.71 6 0.05 —
Boys (n 5 92) Tamano City (n 5 259)
Table 1. Characteristics of the Subjects (mean 6 SD) According to Transforming Growth Factor (TGF)-b1 Genotype
CC 14 (15%) 16.7 6 0.9 173 6 6 65.7 6 7.5 21.9 6 1.9 — 1.01 6 0.13† 0.75 6 0.04§ 6 (2, 10) 0.75 6 0.04§ 5 (2, 9)
REFERENCES
Volume 106
1. Pocock NA, Eisman JA, Hopper JL, et al. Genetic determinants of bone mass in adults: a twin study. J Clin Invest. 1987;80:706 –710. 2. Morrison NA, Qi JC, Tokita A, et al. Prediction of bone density from vitamin D receptor alleles. Nature. 1994;367:284 –287. 3. Harris SS, Eccleshall TR, Gross C, et al. The vitamin D receptor start codon polymorphism (Fok I) and bone mineral density in premenopausal American black and white women. J Bone Miner Res. 1997;12:1043–1048. 4. Kobayashi S, Inoue S, Hosoi T, et al. Association of bone mineral density with polymorphism of the estrogen receptor gene. J Bone Miner Res. 1996;11:306 –311. 5. Grant SFA, Reid DM, Blake G, et al. Reduced bone density and osteoporosis associated with a polymorphic Sp1 binding site in the collagen type Ia1 gene. Nature Genet. 1996;14:203–205. 6. Uitterlinden AG, Burger H, Huang Q, et al. Relation of alleles of the collagen type Ia1 gene to bone density and the risk of osteoporotic fractures in postmenopausal women. NEJM. 1998;338:1016 –1021. 7. Shiraki M, Shiraki Y, Aoki C, et al. Association of bone mineral density with apolipoprotein E phenotype. J Bone Miner Res. 1997; 12:1438 –1445. 8. Bonewald LF. Transforming growth factor-b. In: Bilezikian JP, Raisz LG, Rodan GA, eds. Principles of Bone Biology. San Diego: Academic Press, 1996:647– 659. 9. Hughes DE, Dai A, Tiffee JC, et al. Estrogen promotes apoptosis of murine osteoclasts mediated by TGF-b. Nature Med. 1996;2:1132– 1136. 10. Yamada Y, Miyauchi A, Goto J, et al. Association of a polymorphism of the transforming growth factor-b1 gene with genetic susceptibility to osteoporosis in Japanese women. J Bone Miner Res. 1998;13:1569 –1576. 11. Riggs BL, Khosla S, Melton LJ III. A unitary model for involutional osteoporosis: estrogen deficiency caused both type I and type II osteoporosis in postmenopausal women and contributes to bone loss in aging men. J Bone Miner Res. 1998;13:763–773. 12. Derynck R, Rhee L, Chen EY, van Tilburg A. Intron-exon structure of the human transforming growth factor-b precursor gene. Nucleic Acids Res. 1987;15:3188 –3189. 13. Cambien F, Ricard S, Troesch A, et al. Polymorphisms of the transforming growth factor-b1 gene in relation to myocardial infarction and blood pressure. Hypertension. 1996;28:881– 887. 14. Langdahl BL, Knudsen JY, Jensen HK, Gregersen N, Eriksen EF. A sequence variation: 713-8delC in the transforming growth factorbeta 1 gene has higher prevalence in osteoporotic women than in normal women and is associated with very low bone mass in osteoporotic women and increased bone turnover in both osteoporotic and normal women. Bone. 1997;20:289 –294. From the Department of Geriatric Research (YY, KI), National Institute for Longevity Sciences, Obu; Endocrinology Section (TH), Tokyo Metropolitan Geriatric Hospital, Tokyo; Department of Obstetrics and Gynecol-
Brief Observations ogy (FM), Akiyama Memorial Hospital, Hakodate; and Department of Pediatrics (HT, YS), Okayama University Medical School, Okayama, Japan. Supported in part by a Health Sciences Research Grant for Research on Human Genome and Gene Therapy (to KI) and by a Research Grant for Longevity Sciences (to YY) from the Ministry of Health and Welfare of Japan. Requests for reprints should be addressed to Yoshiji Yamada, MD, Department of Geriatric Research, National Institute for Longevity Sciences, 36-3 Gengo, Morioka, Obu, Aichi 474-8522, Japan. Manuscript submitted September 8, 1998, and accepted in revised form December 8, 1998.
Increased Risk of Exposure to Hepatitis B Infection among Butchers Sharing Knives Dror Mevorach, MD, Mayer Brezis, MD, Fiamenta Ben Yishai, MD, Tomi Sadeh, VMD, Daniel Shouval, MD, Rami Eliakim, MD
T
he risk of hepatitis B virus infection is increased by exposure to blood and blood products. Whereas hepatitis B has long been recognized as an occupational disease in health-care workers (1), other occupations have not been as well studied. Identification of these groups may shed light on the modes of viral transmission and suggest workers who may benefit from targeted vaccination. We recently reported an outbreak of hepatitis B in a butchery in Jerusalem (2). Similar observations have been reported from Australia (3) and Germany (4). To test the hypothesis that butchers are at increased risk of hepatitis B infection, we conducted a cross sectional survey among workers of slaughterhouses and butcheries.
MATERIALS AND METHODS The study sample consisted of 124 workers in three slaughterhouses and 10 butcheries in the Jerusalem district. All subjects answered a questionnaire that included ethnic origin, number of years worked, past or present use of knives at work, frequency of hand cuts, past medical history, and other risk factors for hepatitis B. Workers were divided into butchers who used knives in their routine work and nonbutchers (controls) working in the same business without using knives. Blood samples were collected and tested for antibodies to hepatitis B core antigen (anti-HBc) and to hepatitis C virus (anti-HCV), using a second-generation enzymelinked immunosorbent assay (ELISA; Abbott Laboratories, Chicago, Illinois). Serum samples found positive for
anti-HBc were further tested for hepatitis B surface antigen (HBsAg) and antibody (anti-HBs). Samples that were positive for HBsAg were also tested for e antigen (HBeAg) and hepatitis B viral DNA. Hepatitis B antigens and antibodies were tested by ELISA (Abbott Laboratories, Chicago, Illinois); DNA was assayed by molecular hybridization (5). The chi-square test and Fisher’s exact test were used to compare proportions, and Student’s t test was used to compare continuous variables. A logistic regression model was used to assess the independent effect of occupation, religious background (Muslim, Jewish), and age on the prevalence of exposure to hepatitis B virus. Age was entered as a continuous variable or as a dichotomous variable ($40 years, ,40 years).
RESULTS One hundred twenty-three subjects were included in the study (Table 1). All were men except for one woman in the butcher group. One employee was excluded because of a past blood transfusion. Butchers were younger (P ,0.004) and somewhat more likely to be Moslem (P 5 0.08). However, in a multivariate logistic regression model, only occupation was significantly associated with the prevalence of exposure to hepatitis B virus (odds ratio 5 2.8; 95% confidence interval 1.1 to 7.1). This result was consistent whether age was entered as a continuous or dichotomous variable. At work sites that had no HBsAg-positive workers, only 26% (14 of 54) of the butchers had evidence of hepatitis B infection. However, at the two sites that each had a single HBsAg-positive worker, 57% (16 of 28) of butchers had hepatitis B exposure (P ,0.02). Furthermore, at the butchery with a highly infective HBsAg-positive worker (with positive HBeAg and hepatitis B viral DNA), 4 of the 5 workers had evidence of hepatitis B infection. Table 1. Characteristics of the Butchers and Other Employees (controls)*
Age, years (mean 6 SD) Muslim† More than 1 hand cut per month More than 1 hand cut per week Hepatitis B core antibody positive Antibodies to hepatitis C
Butchers (n 5 82), Number (percent)
Controls (n 5 41), Number (percent)
36 6 5 55 (67) 72 (88) 51 (62) 30 (37) 0
33 6 5 22 (56) 1 (2) 0 7 (17) 0
* Mean age (P ,0.004), reported hand cuts (P ,0.001), and the prevalence of infection with hepatitis B virus (P ,0.05) were significantly different in butchers and controls. † All other subjects were Jewish. April 1999
THE AMERICAN JOURNAL OF MEDICINEt
Volume 106 479