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Cervical collagen and biomechanical strength in non-pregnant women with a history of cervical insufficiency.

Oxlund BS, Ørtoft G, Brüel A, Danielsen CC, Oxlund H, Uldbjerg N - Reprod. Biol. Endocrinol. (2010)

Bottom Line: Maximum load of the specimens did not differ between the groups (p = 0.78).No differences in the volume density of extracellular matrix or smooth muscle cells were found between the two groups.Cervical insufficiency does not appear to be associated with a constitutionally low collagen concentration or collagen of inferior mechanical quality.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby, DK-8200 Aarhus N, Denmark. boxlund@dadlnet.dk

ABSTRACT

Background: It has been suggested that cervical insufficiency (CI) is characterized by a "muscular cervix" with low collagen and high smooth muscle concentrations also in the non-pregnant state. Therefore, the aim of this study was to investigate the biomechanical properties, collagen concentration, smooth muscle cell density, and collagen fiber orientation in cervical biopsies from non-pregnant women with a history of CI.

Methods: Cervical punch biopsies (2 x 15 mm) were obtained from 57 normal non-pregnant women and 22 women with a history of CI. Biomechanical tensile testing was performed, and collagen content was determined by hydroxyproline quantification. Histomorphometry was used to determine the volume densities of extracellular matrix and smooth muscle cells from the distal to the proximal part of each sample. Smooth muscle cells were identified using immunohistochemistry. Finally, collagen fiber orientation was investigated. Data are given as mean +/- SD.

Results: Collagen concentration was lower in the CI group (58.6 +/- 8.8%) compared with the control group (62.2 +/- 6.6%) (p = 0.033). However, when data were adjusted for age and parity, no difference in collagen concentration was found between the two groups. Maximum load of the specimens did not differ between the groups (p = 0.78). The tensile strength of cervical collagen, i.e. maximum load normalized per unit collagen (mg of collagen per mm of specimen length), was increased in the CI group compared with controls (p = 0.033). No differences in the volume density of extracellular matrix or smooth muscle cells were found between the two groups. Fibers not oriented in the plane of sectioning were increased in CI patients compared with controls.

Conclusions: Cervical insufficiency does not appear to be associated with a constitutionally low collagen concentration or collagen of inferior mechanical quality. Furthermore, the hypothesis that a "muscular cervix" with an abundance of smooth muscle cells contributes to the development of cervical insufficiency is not supported by the present study.

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Related in: MedlinePlus

Collagen concentration in cases and controls. Collagen concentration (mg collagen/mg dry defatted weight (DDW) ×100) of cervical samples from women with a history of CI and controls (p = 0.033). After adjustment for age and parity by multiple linear regression, no statistically significant difference in collagen concentration was found between groups (p = 0.2).
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Figure 1: Collagen concentration in cases and controls. Collagen concentration (mg collagen/mg dry defatted weight (DDW) ×100) of cervical samples from women with a history of CI and controls (p = 0.033). After adjustment for age and parity by multiple linear regression, no statistically significant difference in collagen concentration was found between groups (p = 0.2).

Mentions: Collagen concentration was 3.7% lower in the CI-group (58.6 ± 8.8%) (Table 3) compared with the control group (62.2 ± 6.6%) (p = 0.033) (Figure 1). However, as a statistical difference in age and parity was found between the two groups (Table 4), data were adjusted for age and parity. A previous study has shown that the collagen concentration increased 0.5% per year of age and decreased 1.7% per birth [19]. The difference between the two groups was 4.2% (p = 0.02) when adjusted for parity alone, whereas it was 1.6% (p = 0.32) when adjusted for age alone. When adjusted for both age and parity, it was 2.2% and no longer statistically significant (p = 0.2). From these calculations, 43% of the determined difference can be explained due to age, whereas 57% is due to other factors. When collagen concentration in parous women (control group without the 5 ipara) was compared with the CI group, no difference in collagen concentration was found (p = 0.083).


Cervical collagen and biomechanical strength in non-pregnant women with a history of cervical insufficiency.

Oxlund BS, Ørtoft G, Brüel A, Danielsen CC, Oxlund H, Uldbjerg N - Reprod. Biol. Endocrinol. (2010)

Collagen concentration in cases and controls. Collagen concentration (mg collagen/mg dry defatted weight (DDW) ×100) of cervical samples from women with a history of CI and controls (p = 0.033). After adjustment for age and parity by multiple linear regression, no statistically significant difference in collagen concentration was found between groups (p = 0.2).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927597&req=5

Figure 1: Collagen concentration in cases and controls. Collagen concentration (mg collagen/mg dry defatted weight (DDW) ×100) of cervical samples from women with a history of CI and controls (p = 0.033). After adjustment for age and parity by multiple linear regression, no statistically significant difference in collagen concentration was found between groups (p = 0.2).
Mentions: Collagen concentration was 3.7% lower in the CI-group (58.6 ± 8.8%) (Table 3) compared with the control group (62.2 ± 6.6%) (p = 0.033) (Figure 1). However, as a statistical difference in age and parity was found between the two groups (Table 4), data were adjusted for age and parity. A previous study has shown that the collagen concentration increased 0.5% per year of age and decreased 1.7% per birth [19]. The difference between the two groups was 4.2% (p = 0.02) when adjusted for parity alone, whereas it was 1.6% (p = 0.32) when adjusted for age alone. When adjusted for both age and parity, it was 2.2% and no longer statistically significant (p = 0.2). From these calculations, 43% of the determined difference can be explained due to age, whereas 57% is due to other factors. When collagen concentration in parous women (control group without the 5 ipara) was compared with the CI group, no difference in collagen concentration was found (p = 0.083).

Bottom Line: Maximum load of the specimens did not differ between the groups (p = 0.78).No differences in the volume density of extracellular matrix or smooth muscle cells were found between the two groups.Cervical insufficiency does not appear to be associated with a constitutionally low collagen concentration or collagen of inferior mechanical quality.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby, DK-8200 Aarhus N, Denmark. boxlund@dadlnet.dk

ABSTRACT

Background: It has been suggested that cervical insufficiency (CI) is characterized by a "muscular cervix" with low collagen and high smooth muscle concentrations also in the non-pregnant state. Therefore, the aim of this study was to investigate the biomechanical properties, collagen concentration, smooth muscle cell density, and collagen fiber orientation in cervical biopsies from non-pregnant women with a history of CI.

Methods: Cervical punch biopsies (2 x 15 mm) were obtained from 57 normal non-pregnant women and 22 women with a history of CI. Biomechanical tensile testing was performed, and collagen content was determined by hydroxyproline quantification. Histomorphometry was used to determine the volume densities of extracellular matrix and smooth muscle cells from the distal to the proximal part of each sample. Smooth muscle cells were identified using immunohistochemistry. Finally, collagen fiber orientation was investigated. Data are given as mean +/- SD.

Results: Collagen concentration was lower in the CI group (58.6 +/- 8.8%) compared with the control group (62.2 +/- 6.6%) (p = 0.033). However, when data were adjusted for age and parity, no difference in collagen concentration was found between the two groups. Maximum load of the specimens did not differ between the groups (p = 0.78). The tensile strength of cervical collagen, i.e. maximum load normalized per unit collagen (mg of collagen per mm of specimen length), was increased in the CI group compared with controls (p = 0.033). No differences in the volume density of extracellular matrix or smooth muscle cells were found between the two groups. Fibers not oriented in the plane of sectioning were increased in CI patients compared with controls.

Conclusions: Cervical insufficiency does not appear to be associated with a constitutionally low collagen concentration or collagen of inferior mechanical quality. Furthermore, the hypothesis that a "muscular cervix" with an abundance of smooth muscle cells contributes to the development of cervical insufficiency is not supported by the present study.

Show MeSH
Related in: MedlinePlus