535 research outputs found
Functional molecular mass of rat hepatic lipase in liver, adrenal gland and ovary is different
Lipoprotein lipase (LPL) is functionally active only as a dimer. It is
also generally assumed that the highly homologous hepatic lipase functions
as a dimer, but no clear evidence has been presented. A hepatic
lipase-like activity, also indicated as L-type lipase, is present in
adrenal and ovary tissues. This enzyme is thought to originate from the
liver and to be identical to hepatic lipase. We determined the functional
molecular mass of hepatic lipase in rat liver, adrenal gland and ovary by
radiation inactivation, a method for determining the functional size of a
protein without the need of prior purification. Samples were exposed to
ionizing radiation at -135 degrees C. Hepatic lipase activity in liver
homogenate showed a single exponential decay. The functional molecular
mass was calculated to be 63 +/- 10 kDa. Hepatic lipase activity in
adrenal homogenate was found to have a functional molecular mass of 117
+/- 16 kDa. The functional molecular masses of the lipases partially
purified from rat liver perfusate, adrenal homogenate or ovarian
homogenate showed the same pattern, a target mass for the liver enzyme of
56 +/- 6 kDa and a target mass of 117 +/- 14 kDa for the enzyme from
adrenal gland or ovary. In Western blot analysis the mass of the
structural units of hepatic lipase in liver was 57 kDa and in adrenal and
ovary tissue 51 kDa. We conclude that the functional unit of hepatic
lipase in the liver is a monomer. The enzyme in adrenal gland and ovary is
different from the liver and the functional unit may be a dimer
Induction of adrenal scavenger receptor BI and increased high density lipoprotein-cholesteryl ether uptake by in vivo inhibition of hepatic lipase
Hepatic lipase (HL) and scavenger receptor type B class I (SR-BI) have
both been implicated in high density lipoprotein (HDL)-cholesteryl ester
uptake in cholesterol-utilizing tissues. Inactivation of HL by
gene-directed targeting in mice results in up-regulation of SR-BI
expression in adrenal gland (Wang, N., Weng, W., Breslow, J. L., and Tall,
A. R. (1996) J. Biol. Chem. 271, 21001-21004). The net effect on
HDL-cholesteryl ester uptake is not known. We determined the impact of
acute in vivo inhibition of rat adrenal HL activity by antibodies on SR-BI
expression and on human and rat HDL-[3H]cholesteryl ether (CEth) uptake in
the adrenal gland. Rat HDL was isolated from rats in which HL activity had
been inhibited for 1 h. The rats were studied under basal conditions (not
ACTH-treated) and after previous treatment with ACTH for 6 days
(ACTH-treated). Intravenous injection of anti-HL resulted in 70% lowering
of adrenal HL activity in both conditions which were maintained for at
least 8 h. In not ACTH-treated rats, inhibition of adrenal HL increased
adrenal SR-BI mRNA (5.2-fold) and mass (1. 6-fold) within 4 h. HL
inhibition resulted in 41% and 14% more adrenal accumulation of human
HDL-[3H]CEth during 4 and 24 h, respectively. The adrenal uptake of rat
HDL-[3H]CEth increased by 68%, 4 h after the antibody injection. ACTH
treatment increased total adrenal HL activity from 3.7 +/- 0.5 milliunits
to 34.0 +/- 17. 2 milliunits, as well as adrenal SR-BI mRNA from 2.9 +/-
0.7 arbitrary units (A.U.) to 86.8 +/- 41.1 A.U. and SR-BI mass from 7.7
+/- 1.8 A.U. to 63.16 +/- 46.7 A.U. The human HDL-[3H]CEth uptake by
adrenals was also significantly increased from 0.58 +/- 0.11% of injected
dose to 7.24 +/- 1.58% of injected dose. Inhibition of adrenal HL activity
did not result in further induction of SR-BI expression and did not affect
human HDL-[3H]CEth uptake. These findings indicate that SR-BI expression
may be influenced by changes in HL activity. HL activity is not needed for
the SR-BI-mediated HDL-cholester
Spin Nomenclature for Semiconductors and Magnetic Metals
The different conventions used in the semiconductor and magnetic metals
communities can cause confusion in the context of spin polarization and
transport in simple heterostructures. In semiconductors, terminology is based
on the orientation of the electron spin, while in magnetic metals it is based
on the orientation of the moment. In the rapidly expanding field of
spintronics, where both semiconductors and metallic metals are important, some
commonly used terms ("spin-up," "majority spin") can have different meanings.
Here, we clarify nomenclature relevant to spin transport and optical
polarization by relating the common physical observables and "definitions" of
spin polarization to the fundamental concept of conservation of angular
momentum within a well-defined reference frame.Comment: 3 pages, 2 figures, 16 reference
Evaluation of the effect of previous endometriosis surgery on clinical and surgical outcomes of subsequent endometriosis surgery
Purpose Patients often undergo repeat surgery for endometriosis, due to recurrent or residual disease. Previous surgery is often considered a risk factor for worse surgical outcome. However, data are scarce concerning the influence of subsequent endometriosis surgery. Methods A retrospective study in a centre of expertise for endometriosis was conducted. All endometriosis subtypes and intra-operative steps were included. Detailed information regarding surgical history of patients was collected. Surgical time, intra-operative steps and major post-operative complications were obtained as outcome measures. Results 595 patients were included, of which 45.9% had previous endometriosis surgery. 7.9% had major post-operative complications and 4.4% intra-operative complications. The patient journey showed a median of 3 years between previous endometriosis surgeries. Each previous therapeutic laparotomic surgery resulted on average in 13 additional minutes (p = 0.013) of surgical time. Additionally, it resulted in more frequent performance of adhesiolysis (OR 2.96, p < 0.001) and in a higher risk for intra-operative complications (OR 1.81, p = 0.045), however no higher risk for major post-operative complications (OR 1.29, p = 0.418). Previous therapeutic laparoscopic endometriosis surgery, laparotomic and laparoscopic non-endometriosis surgery showed no association with surgical outcomes. Regardless of previous surgery, disc and segmental bowel resection showed a higher risk for major post-operative complications (OR 3.64, p = 0.017 respectively OR 3.50, p < 0.001). Conclusion Previous therapeutic laparotomic endometriosis surgery shows an association with longer surgical time, the need to perform adhesiolysis, and more intra-operative complications in the subsequent surgery for endometriosis. However, in a centre of expertise with experienced surgeons, no increased risk of major post- operative complications was observed.Cervix cance
Hepatic lipase gene expression is transiently induced by gonadotropic hormones in rat ovaries
Hepatic lipase (HL) gene expression was studied in rat ovaries. A transcript lacking exons 1 and 2 could be detected by reverse transcription-polymerase chain reaction (RT-PCR) in the ovaries of mature cyclic females and of immature rats treated with pregnant mare serum followed by human chorionic gonadotropin (hCG) to induce superovulation. By competitive RT-PCR the HL transcript was quantified. Low levels of HL mRNA were detected in ovaries of mature cyclic females and of immature rats. During superovulation HL mRNA was several fold higher than in mature cyclic rats and transiently increased to a maximum at 2 days after hCG treatment. Pulse-labelling of ovarian cells and ovarian slices with [35S]methionine followed by immunoprecipitation with polyclonal anti-HL IgGs showed de novo synthesis of a 47 kDa HL-related protein. Expression of the protein was transiently induced by gonadotropins with a peak at 2 days after hCG treatment. Induction of liver-type lipase activity occurred only after HL mRNA and synthesis of the HL-related protein had returned to pre-stimulatory levels. We conclude that in rat ovaries the HL gene is expressed into a variant mRNA and a 47 kDa protein. The expression of the HL gene in ovaries is inducible and precedes the expression of the mature, enzymatically active liver-type lipase
A log analysis study of 10 years of ebook consumption in academic library collections
Even though libraries have been offering eBooks for more than a decade, very little is known about eBook access and consumption in academic library collections. This paper addresses this gap with a log analysis study of eBook access at the library of the University of Waikato. This in-depth analysis covers a period spanning 10 years of eBook use at this university. We draw conclusions about the use of eBooks at this institution and compare the results with other published studies of eBook usage at tertiary institutes
The F-BAR protein pacsin2 inhibits asymmetric VE-cadherin internalization from tensile adherens junctions
Vascular homoeostasis, development and disease critically depend on the regulation of endothelial cell-cell junctions. Here we uncover a new role for the F-BAR protein pacsin2 in the control of VE-cadherin-based endothelial adhesion. Pacsin2 concentrates at focal adherens junctions (FAJs) that are experiencing unbalanced actomyosin-based pulling. FAJs move in response to differences in local cytoskeletal geometry and pacsin2 is recruited consistently to the trailing end of fast-moving FAJs via a mechanism that requires an intact F-BAR domain. Photoconversion, photobleaching, immunofluorescence and super-resolution microscopy reveal polarized dynamics, and organization of junctional proteins between the front of FAJs and their trailing ends. Interestingly, pacsin2 recruitment inhibits internalization of the VE-cadherin complex from FAJ trailing ends and is important for endothelial monolayer integrity. Together, these findings reveal a novel junction protective mechanism during polarized trafficking of VE-cadherin, which supports barrier maintenance within dynamic endothelial tissue
- âŠ