MRI evaluation of foraminal changes in the cervical spine with assistance of a novel compression device.

Standard supine Magnetic Resonance Imaging (MRI) does not acquire images in a position where most patients with intermittent arm radiculopathy have symptoms. The aim of this study was to test the feasibility of a new compression device and to evaluate image quality and foraminal properties during a Spurling test under MRI acquisition. Ten asymptomatic individuals were included in the study (6 men and 4 women; age range 27 to 55 years). First, the subjects were positioned in the cervical compression device in a 3 T MRI scanner, and a volume T2 weighted (T2w) sequence was acquired in a relaxed supine position (3 min). Thereafter, the position and compressive forces on the patient's neck (provocation position) were changed by maneuvering the device from the control room, with the aim to simulate a Spurling test, causing a mild foraminal compression, followed by a repeated image acquisition (3 min). A radiologist measured the blinded investigations evaluating cervical lordosis (C3-C7), foraminal area on oblique sagittal images and foraminal cross-distance in the axial plane. A total of three levels (C4-C7) were measured on the right side on each individual. Measurements were compared between the compressed and relaxed state. Reliability tests for inter- and intraclass correlation were performed. The device was feasible to use and well tolerated by all investigated individuals. Images of adequate quality was obtained in all patients. A significant increase (mean 9.4, p = 0.013) in the cervical lordosis and a decreased foraminal cross-distance (mean 32%, p < 0.001) was found, during the simulated Spurling test. The area change on oblique sagittal images did not reach a statistically significant change. The reliability tests on the quantitative measures demonstrated excellent intraobserver reliability and moderate to good interobserver reliability. Applying an individualized provocation test on the cervical spine, which simulates a Spurling test, during MRI acquisition was feasible with the novel device and provided images of satisfactory quality. MRI images acquired with and without compression showed changes in cervical lordosis and foraminal cross distance indicating the possibility of detecting changes of the foraminal properties. As a next step, the method is to be tested on symptomatic patients.

Bariatric surgery, osteoarthritis and arthroplasty of the hip and knee in Swedish Obese Subjects - up to 31 years follow-up of a controlled intervention study.

OBJECTIVE: To study the long-term effect of obesity and bariatric surgery on incidences of osteoarthritis and arthroplasty of hip and knee. DESIGN: Hazard ratios (HR) and incidence rates (IR) of osteoarthritis and arthroplasty of hip and knee were studied in the prospective, controlled, non-randomized Swedish Obese Subjects (SOS) study (bariatric surgery group, n = 2007; matched controls given usual obesity care, n = 2040) and the SOS reference cohort (n = 1135, general population). Osteoarthritis diagnosis and arthroplasty for osteoarthritis were captured from the National Swedish Patient Register. Median follow-up time was 21.2 (IQR 16.4-24.8), 22.9 (IQR 19.1-25.7), and 20.1 years (IQR 18.7-20.9) for the control group, surgery group and reference cohort, respectively. RESULTS: The surgery group displayed lower incidence of hip osteoarthritis (IR 5.3, 95% CI 4.7-6.1) compared to controls (IR 6.6, 95% CI 5.9-7.5, adjHR 0.83, 95% CI 0.69-1.00) but similar incidence of hip arthroplasty. Similar incidence of knee osteoarthritis was observed in the surgery group and controls, but knee arthroplasty was more common in the surgery group (IR 7.4, 95% CI 6.6-8.2 and 5.6, 95% CI 4.9-6.4, adjHR 1.45, 95% CI 1.22-1.74). The reference cohort displayed lower incidences of osteoarthritis and arthroplasty of hip and knee compared with the surgery group and controls. CONCLUSION: Bariatric surgery did not normalize the increased risk of knee and hip osteoarthritis in patients with obesity but was associated with an increased incidence of knee arthroplasty compared to the control group. With the limitations inherent to the present data, additional studies are needed to confirm these results. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01479452.

Remission and progression of pre-existing micro- and macroalbuminuria over 15 years after bariatric surgery in Swedish Obese Subjects study.

BACKGROUND: Bariatric surgery reduces incidence of albuminuria and end-stage renal disease in patients with obesity. Effects of bariatric surgery on long-term remission and progression of pre-existing obesity-related renal damage are mainly unexplored. Here we investigate the long-term effects of bariatric surgery compared with conventional obesity care on remission and progression of albuminuria. METHODS: 4047 patients were included in the Swedish Obese Subjects study. Inclusion criteria were age 37-60 years, BMI ≥ 34 kg/m2 in men and BMI ≥ 38 kg/m2 in women. Our analysis comprised 803 patients (19.8% of total population, 357 control, 446 surgery) with pre-existing albuminuria including 693 patients (312 control, 381 surgery) with microalbuminuria, and 110 patients (45 control, 65 surgery) with macroalbuminuria. Surgery patients were treated with banding, vertical banded gastroplasty, or gastric bypass. Control patients received conventional obesity care. RESULTS: Total urinary albumin excretion was 36.5% lower in all patients with albuminuria after 15 years, 44.5% lower in patients with microalbuminuria after 15 years, and 27.8% lower in patients with macroalbuminuria after 2 years following bariatric surgery compared with conventional care. In surgery patients with microalbuminuria, remission to normoalbuminuria was higher (OR, 5.9, 2.2, 3.2, p < 0.001) and progression to macroalbuminuria was lower (OR, 0.28, 0.26, 0.25, p ≤ 0.02) at 2, 10, and 15 years, respectively, compared with control patients. In surgery patients with macroalbuminuria remission to normo- or microalbuminuria was higher (OR, 3.67, p = 0.003) after 2 years. No differences between surgery and control patients with macroalbuminuria were observed after 10 and 15 years. Surgery slowed progression of eGFR decline after 2 years in patients with microalbuminuria and macroalbuminuria (treatment effect: 1.0 ml/min/1.73 m2/year, p = 0.001 and 1.4 ml/min/1.73 m2/year, p = 0.047, respectively). CONCLUSION: Bariatric surgery had better effects than conventional obesity care on remission of albuminuria and prevention of eGFR decline, indicating that patients with obesity-related renal damage benefit from bariatric surgery.

Elevated adiponectin predicts the development of rheumatoid arthritis in subjects with obesity.

Objective The aim of the current study is to determine whether baseline serum adiponectin levels predict the development of rheumatoid arthritis (RA). Method The current report includes 3693 individuals from the Swedish Obese Subjects (SOS) study. The original SOS study is a longitudinal non-randomized controlled study aiming to assess the effect of bariatric surgery on obesity-related mortality and morbidity. Participants included in the present report had adiponectin measurement available at baseline and no prevalent RA. The diagnosis of RA was retrieved through the Swedish National Patient Register. Results During a follow-up for up to 29 years, 82 study participants developed RA. Elevated baseline adiponectin levels were associated with a higher risk of developing RA independently of other factors, including C-reactive protein (CRP) and smoking [hazard ratio (HR) 1.70, 95% confidence interval (CI) 1.12-2.60 for an increase in adiponectin of 10 mg/L, p = 0.01]. After stratifying the population according to adiponectin and CRP median at baseline, study participants with both adiponectin and CRP above the median had a higher risk of developing RA compared to subjects with adiponectin and CRP below the median (HR 2.80, 95% CI 1.25-6.31, p = 0.01). Conclusions In this cohort of subjects with obesity followed up for up to 29 years, high serum adiponectin levels at baseline were associated with an increased risk for RA. Moreover, subjects with both high adiponectin and CRP levels at baseline were at particular risk of developing RA. ClinicalTrials.gov Identifier: NCT01479452.

Diffusion weighted imaging is a promising method to detect acute pyelonephritis in non-sedated free breathing infants.

INTRODUCTION: Urinary tract infection (UTI) is a common disease in infants. The initial evaluation includes imaging to identify risk factors for permanent renal damage, such as malformation and renal parenchymal involvement of the infection i.e. pyelonephritis. 99mTc-Dimercaptosuccinic acid (DMSA) scintigraphy is a well-established method for detection of pyelonephritis and renal damage, but has limitations in availability, spatial resolution, and detection of congenital malformations. Diffusion weighted magnetic resonance imaging (DWI) has been shown to have a high sensitivity for detection of pyelonephritis in children without the use of invasive procedures, contrast agents or ionizing radiation. How this method performs in young infants during non-sedated free breathing remains, however, to be investigated. OBJECTIVE: To prospectively assess the feasibility and performance of DWI for detection of pyelonephritis in non-sedated free breathing infants. METHODS: 32 children <6 months of age with first-time symptomatic UTI were examined with DWI and DMSA scintigraphy. The DWI examination was performed using a free breathing protocol without the use of sedation. Pyelonephritic lesions were registered for both methods by independent observers. Agreement between DWI and DMSA was evaluated. Consensus diagnosis was determined and compared to the DWI findings. RESULTS: The MRI and DMSA examinations were completed in 25 infants, with a median age of 1.7 (0.7-5.5) months. Focal uptake reductions were detected on the DMSA images in 12 (24%) of the 50 kidneys. The DWI method demonstrated a fair to good agreement with DMSA, k = 0.50 (p < 0.0001). The consensus diagnosis was pyelonephritis in eight (16%) of the 50 kidneys. DWI detected seven of the eight kidneys with pyelonephritis. No false positive findings were detected with DWI compared to consensus diagnosis. DISCUSSION: This study has shown an agreement between DWI and DMSA scintigraphy in the detection of pyelonephritis. Further validation of the performance of DWI, using a consensus diagnosis as a reference, confirmed the potential of the method. This feasibility study included a limited number of patients and the results need to be confirmed in a prospective study of a larger cohort. CONCLUSION: Free breathing DWI is a promising method for detection of pyelonephritic lesions in non-sedated infants.

Failure of generic risk assessment model framework to predict groundwater pollution risk at hundreds of metal contaminated sites: Implications for research needs.

Soil pollution constitutes one of the major threats to public health, where spreading to groundwater is one of several critical aspects. In most internationally adopted frameworks for routine risk assessments of contaminated land, generic models and soil guideline values are cornerstones. In order to protect the groundwater at contaminated sites, a common practice worldwide today is to depart from health risk-based limit concentrations for groundwater, and use generic soil-to-groundwater spreading models to back-calculate corresponding equilibrium levels (concentration limits) in soil, which must not be exceeded at the site. This study presents an extensive survey of how actual soil and groundwater concentrations, compiled for all high-priority contaminated sites in Sweden, relate to the national model for risk management of contaminated sites, with focus on As, Cu, Pb and Zn. Results show that soil metal concentrations, as well as total amounts, constitute a poor basis for assessing groundwater contamination status. The evaluated model was essentially incapable of predicting groundwater contamination (i.e. concentrations above limit values) based on soil data, and erred on the "unsafe side" in a significant number of cases, with modelled correlations not being conservative enough. Further, the risk of groundwater contamination was almost entirely independent of industry type. In essence, since neither soil contaminant loads nor industry type is conclusive, there is a need for a supportive framework for assessing metal spreading to groundwater accounting for site-specific, geochemical conditions.

Fracture risk after three bariatric surgery procedures in Swedish obese subjects: up to 26 years follow-up of a controlled intervention study.

BACKGROUND: Previous studies have reported an increased fracture risk after bariatric surgery. OBJECTIVE: To investigate the association between different bariatric surgery procedures and fracture risk. METHODS: Incidence rates and hazard ratios for fracture events were analysed in the Swedish Obese Subjects study; an ongoing, nonrandomized, prospective, controlled intervention study. Hazard ratios were adjusted for risk factors for osteoporosis and year of inclusion. Information on fracture events were captured from the Swedish National Patient Register. The current analysis includes 2007 patients treated with bariatric surgery (13.3% gastric bypass, 18.7% gastric banding, and 68.0% vertical banded gastroplasty) and 2040 control patients with obesity matched on group level based on 18 variables. Median follow-up was between 15.1 and 17.9 years for the different treatment groups. RESULTS: During follow-up, the highest incidence rate for first-time fracture was observed in the gastric bypass group (22.9 per 1000 person-years). The corresponding incidence rates were 10.4, 10.7 and 9.3 per 1000 person-years for the vertical banded gastroplasty, gastric banding and control groups, respectively. The risk of fracture was increased in the gastric bypass group compared with the control group (adjusted hazard ratio [adjHR] 2.58; 95% confidence interval [CI] 2.02-3.31; P < 0.001), the gastric banding group (adjHR 1.99; 95%CI 1.41-2.82; P < 0.001), and the vertical banded gastroplasty group (adjHR 2.15; 95% CI 1.66-2.79; P < 0.001). CONCLUSIONS: The risk of fracture is increased after gastric bypass surgery. Our findings highlight the need for long-term follow-up of bone health for patients undergoing this treatment.

Incidence of end-stage renal disease following bariatric surgery in the Swedish Obese Subjects Study.

BACKGROUND: Obesity is a major public health problem leading to co-morbidities such as diabetes, hypertension and kidney failure. Bariatric surgery results in pronounced and maintained weight loss and prevention of obesity-related diseases and their complications. Most studies of bariatric surgery on kidney disease show improvements after surgery. However, long-term studies analyzing hard end-points are lacking. Here we report on the long-term effects of bariatric surgery compared to usual obesity care on incidence of end-stage renal disease (ESRD) alone and in combination with chronic kidney disease stage 4 (CKD4/ESRD). METHODS: 4047 patients were included in the Swedish Obese Subjects (SOS) study. Inclusion criteria were age 37-60 years and BMI ≥ 34 in men and BMI ≥ 38 in women. Patients in the bariatric surgery group (N = 2010) underwent banding (18%), vertical banded gastroplasty (69%), or gastric bypass (13%); controls (N = 2037) received usual obesity care. In this analysis, patients were followed up for a median time of 18 years. The incidence of ESRD and CKD4 was obtained by crosschecking the SOS database with the Swedish National Patient Register. RESULTS: During follow-up, ESRD occurred in 13 patients in the surgery group and in 26 patients in the control group (adjusted hazard ratio (HR) = 0.27; 95% CI 0.12-0.60; p = 0.001). The number of CKD4/ESRD events was 23 in the surgery group and 39 in the control group (adjusted HR = 0.33; 95% CI 0.18-0.62; p < 0.001). In both analyses, bariatric surgery had a more favorable effect in patients with baseline serum insulin levels above median compared to those with lower insulin levels (interaction p = 0.010). Treatment benefit of bariatric surgery was also greater in patients with macroalbuminuria at baseline compared to those without macroalbuminuria (interaction p < 0.001). CONCLUSIONS: Our study showed for the first time that bariatric surgery is associated with a long-term protection against ESRD and CKD4/ESRD.

The incidence of albuminuria after bariatric surgery and usual care in Swedish Obese Subjects (SOS): a prospective controlled intervention trial.

BACKGROUND: Obesity is associated with increased risk of chronic kidney disease and albuminuria is a predictor of renal impairment. Bariatric surgery reduces body weight in obese subjects, but it is not known whether surgery can prevent development of albuminuria. This study aims to determine the long-term effect of bariatric surgery on the incidence of albuminuria. SUBJECTS: The Swedish Obese Subjects study is a non-randomized, prospective, controlled study conducted at 25 public surgical departments and 480 primary health care centers in Sweden. Between 1 September 1987 and 31 January 2001, 2010 participants who underwent bariatric surgery and 2037 controls were recruited. Inclusion criteria were age 37-60 years and BMI ⩾ 34 in men and BMI ⩾ 38 in women. In this analysis, we included 1498 patients in the surgery group and 1610 controls without albuminuria at baseline. Patients in the bariatric surgery group underwent banding (18%), vertical banded gastroplasty (69%) or gastric bypass (13%); controls received usual obesity care. Date of analysis was 1 January 2011. Median follow-up was 10 years, and the rates of follow-up were 87%, 74 and 52% at 2, 10 and 15 years, respectively. The main outcome of this report is incidence of albuminuria (defined as urinary albumin excretion >30 mg per 24 h) over up to 15 years. RESULTS: During the follow-up, albuminuria developed in 246 participants in the control group and in 126 in the bariatric surgery group, corresponding to incidence rates of 20.4 and 9.4 per 1000 person years, respectively (adjusted hazard ratio, 0.37; 95% confidence interval, 0.30-0.47; P < 0.001). The expected number of surgeries needed to prevent the development of albuminuria in one patient at 10 years was nine. CONCLUSIONS: Bariatric surgery is associated with reduced incidence of albuminuria compared with usual obesity care.

Macrophage gene expression in adipose tissue is associated with insulin sensitivity and serum lipid levels independent of obesity.

OBJECTIVE: Obesity is linked to both increased metabolic disturbances and increased adipose tissue macrophage infiltration. However, whether macrophage infiltration directly influences human metabolism is unclear. The aim of this study was to investigate if there are obesity-independent links between adipose tissue macrophages and metabolic disturbances. DESIGN AND METHODS: Expression of macrophage markers in adipose tissue was analyzed by DNA microarrays in the SOS Sib Pair study and in patients with type 2 diabetes and a BMI-matched healthy control group. RESULTS: The expression of macrophage markers in adipose tissue was increased in obesity and associated with several metabolic and anthropometric measurements. After adjustment for BMI, the expression remained associated with insulin sensitivity, serum levels of insulin, C-peptide, high density lipoprotein cholesterol (HDL-cholesterol) and triglycerides. In addition, the expression of most macrophage markers was significantly increased in patients with type 2 diabetes compared to the control group. CONCLUSION: Our study shows that infiltration of macrophages in human adipose tissue, estimated by the expression of macrophage markers, is increased in subjects with obesity and diabetes and associated with insulin sensitivity and serum lipid levels independent of BMI. This indicates that adipose tissue macrophages may contribute to the development of insulin resistance and dyslipidemia.

Female ornamentation and egg carotenoids of six sympatric gobies.

Belly colouration, gonad carotenoid concentration and skin transparency were quantified in gravid Gobiusculus flavescens, as well as in females of five sympatric gobies where belly ornamentation has not been described. Although G. flavescens females did, indeed, have far more colourful bellies than the other species, this could only in part be explained by a high concentration of total gonad carotenoids. Comparable, or occasionally higher, carotenoid levels were found in the gonads of other species. Instead, the unusual ornamentation of G. flavescens arises from a unique combination of carotenoid-rich gonads and a highly transparent abdominal skin.

Increased expression of aquaporin 3 in atopic eczema.

BACKGROUND: Dry skin in atopic eczema depends on increased water loss. The mechanisms behind this are poorly understood. The aim of this work was to identify genes that may contribute to water loss in eczema. METHODS: Affymetrix DNA microarrays U133A were used to analyse gene expression in skin biopsies from 10 patients with atopic eczema and 10 healthy controls. RESULTS: DNA microarray analysis showed up-regulation of 262 genes and down-regulation of 129 genes in atopic eczema. The known functions of these genes were analysed using Gene Ontology to identify genes that could contribute to increased water loss. This led to identification of aquaporin 3 (AQP3), which has a key role in hydrating healthy epidermis. Increased expression of AQP3 was found in eczema compared with healthy skin. This was confirmed with real-time polymerase chain reaction (P<0.001). In healthy skin, epidermal AQP3 immunoreactivity was weak and mainly found in the stratum basale. A gradient was formed with decreasing AQP3 staining in the lower layers of the stratum spinosum. By contrast, in acute and chronic atopic eczema strong AQP3 staining was found in both the stratum basale and the stratum spinosum. CONCLUSIONS: Aquaporin 3 is the predominant aquaporin in human skin. Increased expression and altered cellular distribution of AQP3 is found in eczema and this may contribute to water loss.

Methodological studies of multiple reference genes as endogenous controls in vascular gene expression studies.

Detection and quantification of differentially expressed genes requires valid and reliable references to control for error variability introduced by preparatory procedures or efficiency of reverse transcription and polymerase chain reaction (PCR) amplification conditions. So-called housekeeping genes are frequently used as endogenous standards, based on the assumption that they are constitutively expressed and independent of experimental conditions. However, if the influence of experimental stimuli is to be analyzed, it cannot a priori be assumed that their expression is unaffected by stimulation. In the present study, the authors studied the expression of different housekeeping genes in the vascular endothelium of intact conduit vessels perfused in a unique biomechanical perfusion model. Ten control gene candidates were investigated by microarray expression analysis. Further, five of these genes were systematically analyzed by real-time reverse transcriptase (RT)-PCR gene quantification and their suitability as reference genes were evaluated. On the basis of these findings, the authors suggest criteria for evaluation of endogenous control genes in vascular perfusion studies.

Effects of experimental Schistocephalus solidus infections on growth, morphology and sexual development of female three-spined sticklebacks, Gasterosteus aculeatus.

The use of naturally infected hosts in studies attempting to identify parasite-induced changes in host biology is problematical because it does not eliminate the possibility that infection may be a consequence, rather than a cause, of host trait variation. In addition, uncontrolled concomitant infections may confound results. In this study we experimentally infected individual laboratory-bred female three-spined sticklebacks Gasterosteus aculeatus L. with the pseudophyllidean cestode Schistocephalus solidus [Müller], and compared the morphology and growth patterns of infected females with sham-exposed controls over a 16-week period. Fish were fed a ration of 8% body weight per day. Non-invasive image analysis techniques allowed the growth of individual plerocercoids to be tracked in vivo throughout the course of infection, and patterns of host and parasite growth were determined. Females that developed infections diverged morphometrically from unexposed control females and exposed-uninfected females at 6 weeks post-infection, with the width of the body at the pectoral fins giving the earliest indication of infection success. When including the plerocercoid, infected females gained weight more quickly than controls, but when plerocercoid weight was removed this trend was reversed. There was no effect of infection on the increase in fish length. Plerocercoids grew at different rates in individual hosts, and exhibited measurable sustained weight increases of up to 10% per day. Final estimates of plerocercoid weight from morphometric analysis prior to autopsy were accurate to within +/- 17% of actual plerocercoid weight. At autopsy, infected female sticklebacks had significantly lower perivisceral fat reserves but had developed significantly larger ovaries than controls. The results are discussed in relation to previous studies examining natural infections, and the value of utilizing experimental infections to examine ecological aspects of host-parasite interactions is discussed.

DNA microarrays to study gene expression in allergic airways.

BACKGROUND: Allergic rhinitis results from interactions between a large number of cells and mediators in different compartments of the body. DNA microarrays allow simultaneous measurement of expression of thousands of genes in the same tissue sample. OBJECTIVE: To study gene expression in nasal mucosal biopsies from patients with allergic rhinitis using DNA micro-arrays. METHODS: Nasal biopsies were obtained from 14 patients with symptomatic birch pollen-induced allergic rhinitis and five healthy controls. RNA was extracted from the biopsies and pooled into one patient pool and one control pool. These were analysed in duplicate with DNA micro-arrays containing more than 12 000 known genes. RESULTS: Approximately half of the genes were expressed in the patient and control samples. Guided by the current literature we chose 32 genes of possible relevance to allergic airway inflammation and investigated their relative expression. Among these, transcripts encoding immunoglobulins and their receptors were most abundant. The expression of cytokines and growth factors was low, whereas their corresponding receptors and cell surface markers displayed higher expression levels. IgA had the highest expression of all 12 626 genes. RT-PCR showed that IgA1 was the predominant subclass. This was confirmed by the protein level in nasal fluids. Allergen-specific IgA was significantly higher in patients than in controls and correlated significantly with eosinophil granulae proteins. CONCLUSION: DNA micro-array analysis can be used to identify genes of possible relevance to allergic airway inflammation. In this study, the expression profile in the nasal mucosa was quantitatively dominated by immunoglobulins, particularly IgA. Protein analyses in nasal fluids indicated a role for allergen-specific IgA in eosinophil degranulation.

Isolation of differentially expressed aldose reductase in ovaries after estrogen withdrawal from hypophysectomized diethylstilbestrol treated rats: increased expression during apoptosis.

More than 99% of the follicles are eliminated by apoptosis before reaching ovulation. Several growth factors and hormones inhibit apoptosis in the ovary, including estrogen. Using differential display of mRNA, aldose reductase was shown to increase in the ovary of diethylstilbestrol treated hypophysectomized rats after estrogen withdrawal, inducing apoptosis. The aldose reductase mRNA expression was confirmed to be 2.2 +/- 0.2-fold higher after estrogen withdrawal using northern blot analysis. In addition, untreated immature rats showed a 1.7 +/- 0.3-fold higher expression of ovarian aldose reductase mRNA compared to ovaries 24 h after pregnant mare's serum gonadotropin treatment, decreasing apoptosis in the ovary. In the prostate, the level of aldose reductase was increased 3.1 +/- 1.1-fold 2 days after castration induced apoptosis. Although the physiological role of aldose reductase in the ovary is not known, these data suggest that aldose reductase may be part of a hormonally regulated apoptotic pathway in the ovary and prostate.

Scavenger receptor class B type I in the rat ovary: possible role in high density lipoprotein cholesterol uptake and in the recognition of apoptotic granulosa cells.

Scavenger receptor class B type I (SR-BI) mediates the selective uptake of high density lipoprotein cholesterol. SR-BI is expressed at high levels in the ovary, indicating that it plays a role in the delivery of cholesterol as substrate for steroid hormone production. However, SR-BI also binds anionic phospholipids with high affinity and could therefore be involved in the recognition of apoptotic cells. In this study we have characterized the expression of SR-BI in rat ovarian follicles undergoing atresia. Atretic follicles with cells undergoing apoptosis were identified by in situ DNA end labeling, and SR-BI expression was determined by in situ hybridization and immunohistochemistry. SR-BI was expressed in thecal cells at all stages of follicular development, including atretic follicles, and in corpus luteum. Isolated apoptotic granulosa cells (but not viable granulosa cells) bound annexin V, indicating that they display anionic phospholipids on the cell surface. Transfection of COS-7 cells with an expression vector carrying the rat SR-BI complementary DNA resulted in increased binding to apoptotic granulosa cells (46 +/- 2% of the SR-BI-expressing cells bound at least one granulosa cell compared with 24 +/- 3% for the mock-transfected cells; P < 0.0001), whereas the binding to viable granulosa cells was unchanged. Apoptotic granulosa cells also bound to isolated thecal shells. We conclude that thecal cells of both nonatretic and atretic follicles express SR-BI. The location of SR-BI expression in the ovary supports a role of this receptor in the uptake of high density lipoprotein cholesterol. In addition, our data suggest that SR-BI mediates the recognition of apoptotic granulosa cells by the surrounding thecal cells and that it therefore may play a role in the remodeling of atretic follicles to secondary interstitial cells.

Cloning of two novel growth hormone transcripts expressed in human placenta.

Several isoforms of human GH (hGH) are produced by two related genes expressed in the pituitary (hGH-N) and in the placenta (hGH-V). These genes consist of five exons (denoted 1-5) separated by four introns (denoted A-D). In the present report, two new transcripts of the hGH-V gene are described. The coding region of the hGH-V gene was amplified by RT-PCR using placental complementary DNA as template. DNA sequencing of several clones revealed two novel transcripts. One had a 45-bp deletion caused by the use of an alternative splice acceptor site within exon 3, similar to that in the hGH-N gene, predicting a 20-kDa isoform of hGH-V. The other transcript was generated by the use of an alternative splice donor site causing a 4-bp deletion in the end of exon 4, predicting a 24-kDa protein with 219 amino acids, which we refer to as hGH-V3. The carboxy-terminal sequence of hGH-V3 differs from 22-kDa hGH-V and hGH-V2, the two previously reported transcripts of the hGH-V gene, and does not contain a predicted transmembrane domain as described for hGH-V2. Ligase chain reaction was then used to analyze the possible use of the same splicing pattern in transcripts derived from the other genes of the hGH-gene cluster. Alternatively spliced transcripts encoding the 20-kDa hGH isoform were detected from the hGH-N and hGH-V genes, but not from the human chorionic somatomammotropin-A/B genes. The alternative splicing generating hGH-V3 was only demonstrated in transcripts derived from the hGH-V gene. Using competitive RT-PCR, the expression of hGH-V3 was estimated to be 10% of the hGH-V messenger RNA in full-term normal placentas and in placentas from pathological pregnancies. The 20-kDa hGH-V was detected in two of four full-term normal placentas, whereas a weak signal was observed in one of the pathological placentas. We conclude that the hGH-V primary transcript undergoes alternative splicing pathways generating at least four different messenger RNAs, predicting the expression of different hGH isoforms, including two with a complete sequence divergence in the carboxy-terminus.

Characterization and chromosomal localization of rat scavenger receptor class B type I, a high density lipoprotein receptor with a putative leucine zipper domain and peroxisomal targeting sequence.

High density lipoprotein (HDL) participates in reverse cholesterol transport and in the delivery of cholesterol to steroid-producing tissues. Scavenger receptor class B type I (SR-BI) was recently shown to bind HDL and mediate internalization of its cholesterol content. We have cloned the rat homolog of this receptor, determined its chromosomal location, and examined its expression in rat tissues and in a model of follicular development, ovulation, and luteinization. The predicted protein contained two transmembrane domains, a leucine zipper motif, and a peroxisomal targeting sequence. The rat and human SR-BI genes were mapped to a region previously linked between rat and human chromosomes 12. SR-BI gene expression was detected in several rat tissues, with high levels in ovarian tissue, liver, and adrenal cortex, as determined by ribonuclease protection assay and in situ hybridization. A significant increase in SR-BI gene expression was detected in the late phase of corpus luteum formation, and transcripts were abundant in corpus luteum and in thecal cells at all stages of follicular development. In conclusion, the rat SR-BI complementary DNA predicted a protein with several conserved motifs, including a putative leucine zipper and a peroxisomal targeting sequence. The chromosomal locations of the rat and human SR-BI homologs suggest that this gene is a new member of a previously reported, conserved synteny group. SR-BI gene expression was high in steroid-producing tissues and in the liver, consistent with a role of this receptor in the uptake of HDL cholesterol.