bluuebunny/crossref_metadata_2025 huggingface dataset:
Dehydroepiandrosterone supplementation in women with adrenal failure: impact on twenty‐four hour GH secretion and IGF‐related parameters
Authors: Christiansen Jens Juel , Gravholt Claus Højbjerg , Fisker Sanne , Svenstrup Birgit , Bennett Paul , Veldhuis Johannes , Andersen Marianne , Christiansen Jens S. , Jørgensen Jens O. L.
Published: December 2004

objective  In women, GH secretion is strongly influenced by oestrogen status, whereas the role of androgens is unclear. We, therefore, examined GH secretory dynamics during low vs. normalized androgen levels in women with adrenal failure.

patients  Ten females with adrenal failure (AF), mean age of 42 years (range 22–54 years).

design  The effects of 8 days of oral dehydroepiandrosterone (DHEA; 50 mg/day) were studied in a double‐blind placebo‐controlled, cross‐over design. A control group of healthy women was studied once without any treatment.

measurements  Before and after each treatment period, blood was sampled for measurement of androgens, IGF‐I, IGFBP‐3 and GHBP. A 24‐h GH profile with measurements every 20 min was performed at the end of each period.

results  DHEA supplementation normalized the mean circulating levels of testosterone and androgen precursors. The secretory pattern of GH was unaltered during DHEA [placebo vs. DHEA; half‐life 22·83 ± 1·24 vs. 21·45 ± 1·19 (min), P = 0·429; pulse frequency 9·9 ± 0·7 vs. 10·5 ± 0·5 (/24 h), P = 0·502; total production rate 62·27 ± 13·44 vs. 52·61 ± 7·06 (µg/l/day), P = 0·317]. Subgroup analysis, however, indicated that DHEA treatment increased GH secretion in patients not receiving oestrogen (n = 5), whereas the opposite was observed among patients receiving exogenous oestrogen derivatives (n = 5). Compared to the control group (CON), GH half‐life was longer in AF (half‐life CON: 16·48 ± 0·91, P = 0·001). The additional features of GH secretion were similar. Unexpectedly, the levels of IGF‐I, IGFBP‐3 and GHBP were elevated in the patients as compared to controls, without significant effects of DHEA [AF vs. CON. IGF‐I: 186 ± 20 vs. 144 ± 7 (µg/l), P = 0·04; IGFBP‐3: 5196 ± 224 vs. 3687 ± 212 (µg/l), P = 0·001; GHBP: 2·27 ± 0·25 vs. 1·41 ± 0·13 (nmol/l), P = 0·002].

conclusion  (1) Short‐term DHEA administration in women with adrenal failure normalizes the circulating levels of androgens without uniformly affecting the GH–IGF axis; (2) The observation that exogenous oestradiol may mask a stimulatory effect of DHEA on GH secretion merits future investigation.
Elevated leptin fragments in renal failure correlate with BMI and haematopoiesis and are normalized by haemodialysis
Authors: Stamatiadis Dimitrios N. , Chan Jean L. , Cogswell Rebecca , Stefanopoulou Helen C. , Bullen John , Katsilambros Nicholas , Stathakis Charalambos P. , Mantzoros Christos S.
Published: December 2004

objective  Leptin is an adipocyte hormone important in appetite, energy homeostasis, neuroendocrine and haematopoietic function. Patients with renal failure often have elevated total and free leptin levels. Biologically active leptin fragments (leptin22−56 and leptin57−92) have been identified, but whether these fragments are affected by renal failure and/or haemodialysis (HD) is not known.

research methods  Leptin, leptin22−56 and leptin57−92 levels were measured in 28 HD patients [14 men, 14 women, age 45·5 ± 16·4 years, body mass index (BMI) 23·8 ± 3·6 kg/m2] and 25 healthy controls with similar age and BMI. In 18 HD patients, leptin and fragment levels were measured before and after 2 consecutive dialysis treatments and on the intermediate, dialysis‐free day.

results  Baseline leptin levels were higher in HD patients vs. controls (69·3 ± 62·2 ng/ml vs. 30·4 ± 32·7, P < 0·02) as were leptin22−56 (7·14 ± 7·04 ng/ml vs. 1·86 ± 1·84, P < 0·02) and leptin57−92 (5·94 ± 6·08 ng/ml vs. 1·58 ± 1·98, P < 0·02). Baseline leptin and fragment levels correlated significantly and independently with BMI in HD patients (r = 0·70, r = 0·59, r = 0·72, respectively, P < 0·001). After each HD session, leptin levels were reduced to levels not different from controls, but increased on the intermediate, dialysis‐free day. Similar to and independently from total leptin, both leptin fragments were reduced after the first HD session to levels not different from controls. The reduction in leptin levels was higher with synthetic vs. cellulosic membrane types (37·7 ± 23·5%vs. 18·1 ± 21·8%, P < 0·03). Leptin correlated weakly with the erythropoietin to haematocrit ratio (T = −0·20, P = 0·14), while leptin22−56 had a significant negative correlation with this index (T = −0·42, P < 0·01), suggesting that this fragment may favour haematopoiesis.

discussion  Leptin fragments are detected in human serum, and both leptin and leptin fragments correlate with BMI, are significantly elevated in HD patients compared to controls, and are significantly decreased by haemodialysis. The elevated leptin fragments may have important physiological significance for the anorexia, hypogonadism, and anaemia commonly seen in HD patients, but this remains to be conclusively shown by interventional trials.
Sources of glucose variability in insulin‐treated type 2 diabetes: the Diabetes Outcomes in Veterans Study (DOVES)
Authors: Murata Glen H. , Duckworth William C. , Shah Jayendra H. , Wendel Christopher S. , Hoffman Richard M.
Published: December 2004

objective  Glucose variability can be a significant barrier to glycaemic control for diabetic patients on insulin. The study identified clinical and behavioural factors associated with glucose variability in type 2 diabetes.

design  Observational study.

subjects  Randomly selected veterans with stable, insulin‐treated type 2 diabetes.

measurements  Baseline data included demographics, clinical characteristics, diet, activity and haemoglobin A1c. Subjects self‐monitored blood glucose before all meals and at bedtime for 8 weeks. Monitoring data were used to derive an overall glucose mean and glucose coefficient of variation (100*SD/mean) for each subject. Univariate and multivariate analyses were used to evaluate the relationship between glucose coefficient of variation and clinical factors.

results  Two‐hundred and four subjects completed the protocol. The 8‐week mean (± SD) glucose was 9·9 ± 2·2 mmol/l, and the average overall coefficient of variation was 35·6 ± 7·7%. Univariate analysis showed a higher variation in older subjects and in those with longer duration of insulin treatment, greater consumption of sugars and greater confidence in their self‐care abilities. Variation was lower in subjects who were obese, more compliant with medications and receiving larger insulin doses. Multivariate analysis showed that treatment duration, sugar consumption, medication compliance and insulin dose were independently associated with glucose variation. Medication compliance was more influential for fasting variation, while body mass index was more influential for before lunch variation.

conclusions  Numerous behavioural, clinical and treatment factors were independently associated with glucose variability. Reducing sugar consumption and improving medication compliance might offset the greater glucose fluctuation observed in lean patients with longstanding diabetes.
Variability in anterior pituitary size within members of a family with GH deficiency due to a new splice mutation in the GHRH receptor gene
Authors: Alba Maria , Hall Catherine M. , Whatmore Andrew J. , Clayton Peter E. , Price David A. , Salvatori Roberto
Published: December 2004

objective  Mutations in the GHRH receptor (GHRHR) gene (GHRHR) cause autosomal recessive isolated GH deficiency (IGHD), and are usually associated with anterior pituitary hypoplasia (APH) (defined as pituitary height more than 2 SDS below normal). We searched for GHRHR mutations and studied pituitary morphology in three prepubertal sibs with severe IGHD, who were born from consanguineous parents.

design  We sequenced the 13 exons and the intron–exon boundaries of the GHRHR of the index patient. After identifying a novel mutation, we sequenced the same area in the other family members. In addition, we performed magnetic resonance imaging (MRI) study of the pituitary (at age 8, 4 and 3 years) in the three affected subjects.

results  The three children were homozygous for a new GHRHR mutation that alters the second base of the invariant 5′ splice site (GT) of intron 12 [IVS12 + 2T→A]. The parents and an unaffected sibling were heterozygous for the same change. MRI did not show frank APH (by height criteria) in any of the subjects: pituitary height was normal (5·6 mm, +1·8 SDS) in the oldest sibling, and it was low but not below 2 SDS by age‐adjusted criteria in the second (3 mm, −1·4 SDS), and third sibling (2·8 mm, −1·7 SDS). Calculated pituitary volume was below −2 SDS in the youngest patient.

conclusions  These data demonstrate that pituitary height may fall within 2 SDS from the norm in patients with severe IGHD due to a homozygous GHRHR mutation, and that pituitary size may vary within patients with identical mutations who belong to the same family.
First trimester levels of inhibins and activin A in normal and failing pregnancies
Authors: Wallace Euan M. , Marjono Budi , Tyzack Katrina , Tong Stephen
Published: December 2004

objective  Miscarriage is the commonest complication of human pregnancy. We undertook this study to assess whether inhibin A, pro‐αC inhibin and/or activin A, products of the corpus luteum and placenta, might be useful in either the prediction or diagnosis of miscarriage.

design  Case–control study.

patients  Ninety‐eight asymptomatic women at 6–13 weeks gestation who subsequently had a miscarriage and 198 gestation‐matched women with a normal singleton pregnancy.

measurements  Maternal serum levels of inhibin A, pro‐αC inhibin, activin A and human chorionic gonadotrophin (hCG) were measured.

results  Inhibin A, pro‐αC and hCG, expressed as multiples of the normal median (MoM; ±95% confidence intervals) in the miscarriage cases were significantly lower than in the viable controls, 0·56 (0·48–0·69) MoM vs. 1·00 (0·98–1·13) MoM, 0·55 (0·51–0·84) MoM vs. 1·0 (0·86–1·22) MoM and 0·34 (0·23–0·36) MoM vs. 1·00 (0·94–1·08) MoM, respectively (P < 0·0001 for all). Of the three analytes, hCG was the most discriminating between cases and controls. Levels of activin A in the miscarriage cases were not significantly different from controls, 0·96 (0·86–1·07) vs. 1·0 (0·95–1·08).

conclusions  These data suggest that inhibin A, pro‐αC inhibin and activin A will not be useful in either the prediction or diagnosis of early pregnancy miscarriage.
IGF‐I and testosterone levels as predictors of bone mineral density in healthy, community‐dwelling men
Authors: Rucker Diana , Ezzat Shereen , Diamandi Anastasia , Khosravi Javad , Hanley David A.
Published: December 2004

objective  Age‐related decline in IGF‐I and gonadal hormones have been postulated to play an important role in the pathogenesis of age‐related bone loss in men. In this cross‐sectional study, the relation between serum IGF‐I and gonadal hormones with bone mineral density (BMD) was examined in community‐dwelling men.

design and subjects  Serum IGF‐I, testosterone and BMD were examined in 61 community‐dwelling men over the age of 27, who were randomly selected from the Calgary cohort of 1000 subjects in the Canadian Multicentre Osteoporosis Study. In the present study, IGF‐I, serum testosterone, SHBG, free androgen index (FAI), parathyroid hormone (PTH), 25‐hydroxy‐vitamin D [25(OH)D] and other markers of bone turnover were measured. BMD was measured at the spine and hip (HOLOGIC 4500). Simple linear regression was used to assess the linear relation between IGF‐I, testosterone, BMD and other biochemical markers of bone metabolism and potential confounding variables and subsequent multivariate regression models were constructed separately for each BMD measurement to assess the importance of IGF‐I and testosterone in the presence of potential confounding variables.

results  Serum IGF‐I, FAI and SHBG significantly decreased as a function of age, whereas serum levels of PTH increased. Only 25(OH)D, total testosterone and FAI were positively associated with serum IGF‐I after adjusting for age and BMI. Multiple linear regression models revealed that IGF‐I was a significant predictor of BMD at the total hip, femoral neck and femoral trochanter neck (P ≤ 0·001). In contrast, the FAI was a significant predictor of BMD at the lumbar spine and wards area (P ≤ 0·011), and SHBG was a significant predictor at the total hip and femoral trochanter (P ≤ 0·045).

conclusion  These data support the hypothesis that the age‐related decline in bone mass in men is associated with declining levels of IGF‐I and testosterone.
Gender variation in PTH sensitivity and rhythmicity following growth hormone replacement in adult growth hormone‐deficient patients
Authors: White H. D. , Ahmad A. M. , Syed A. A. , Clewes A. , Peter R. , Vora J. P. , Fraser W. D.
Published: December 2004

background  Adult GH deficiency (AGHD) is associated with osteoporosis and reduced bone turnover; factors improved by GH replacement (GHR), with men gaining greater benefit than women. Reduction in sensitivity of bone and kidney to the effects of PTH may underlie AGHD changes in bone turnover. We determined the gender difference in PTH target‐organ sensitivity following GHR in AGHD patients.

design, patients and measurements  Twenty AGHD patients (10 men) were admitted to hospital before and after GHR initiation. Half‐hourly blood samples were collected for PTH, calcium, nephrogenous cyclic AMP (NcAMP, marker of PTH activity), type‐I collagen C‐telopeptide (CTX, bone resorption marker) and procollagen type‐I amino‐terminal propeptide (PINP, bone formation marker).

results  The 24‐h mean PTH concentration decreased in both genders (P < 0·001), with maximal changes seen 6 and 12 months following GHR in men and women, respectively. Increases in 24‐h mean NcAMP (P < 0·05), calcium (P < 0·001) and bone turnover markers (P < 0·001) occurred in both genders following GHR, with maximal changes at 1 month in men, but at 3 months for NcAMP, calcium and CTX and 12 months for PINP in women. Maximal NcAMP increase was higher in men (P = 0·009).

conclusions  Following GHR, PTH target‐organ sensitivity increased in both genders, demonstrated by simultaneous reduction in PTH concentration and increase in NcAMP, calcium and bone turnover. In women, improvement in renal PTH sensitivity was delayed and reduced, and changes in bone turnover were delayed, with increase in bone resorption preceding bone formation. Both factors may contribute to the reduced bone mineral density (BMD) response to GHR observed in women.
Earlier initiation of GH therapy does not influence adult height but enables earlier start of pubertal induction in children with multiple pituitary hormone deficiency
Authors: Kawai Masahiko , Momoi Toru , Mamada Mitsukazu , Yorifuji Tohru , Nakahata Tatsutoshi
Published: December 2004

objective  For patients with GH and gonadotrophin deficiency, adult height and sexual maturation are important not only for their physical but also psychological status. GH therapy is usually initiated soon after diagnosis but the differences in the age for initiation of therapy have not been previously examined. In this study, we assessed the influence of timing of initiation of GH therapy on adult height and the time of initiation of pubertal induction.

design, patients and measurements  Height‐related data from 16 short children (13 boys and three girls) with GH and gonadotrophin deficiency who reached adult height after 10·9 ± 2·3 years of GH therapy were analysed retrospectively.

results  Adult height (0·00 ± 0·69 SD) improved remarkably compared to height SDS at the start of GH therapy (−3·75 ± 0·94 SD). The age at which GH therapy was started ranged from 3·2 to 12·0 years, but we found that such a difference in age did not affect adult height. However, an earlier start of GH therapy allowed earlier pubertal induction without loss of height potential.

conclusions  Earlier initiation of GH therapy is not required for normalization of adult height in patients with GH and gonadotrophin deficiency but it makes earlier pubertal induction possible, which is important for quality of life.
Lack of association of the vitamin D receptor gene with Graves’ disease in UK Caucasians
Authors: Collins J. E. , Heward J. M. , Nithiyananthan R. , Nejentsev S. , Todd J. A. , Franklyn J. A. , Gough S. C. L.
Published: December 2004

objective  Vitamin D modulates the immune system by suppressing the proliferation of activated T cells, with its actions being directed through the vitamin D receptor (VDR). A number of single nucleotide polymorphisms (SNPs) have been identified in the VDR gene, of which several have been associated with autoimmune diseases, including type 1 diabetes and Graves’ disease (GD) in Japanese females. The aim of this study was to test for association of polymorphisms of the VDR gene in the genetic susceptibility to GD in UK Caucasians.

design  Target DNA for five previously published SNPs, four novel SNPs and one microsatellite marker was amplified by the polymerase chain reaction (PCR). Subsequent genotyping was performed using restriction fragment length polymorphism (RFLP) or microsatellite genotyping analysis, according to the type of VDR polymorphism.

patients  We obtained DNA from a case–control dataset consisting of 768 patients with GD and 864 control subjects. All patients and control subjects were Caucasians born in the UK, and all gave informed, written consent.

measurements  Frequencies of the alleles and genotypes of the ten VDR gene polymorphisms were compared between patients and control subjects using the χ2 test. Odds ratios were calculated using Woolf's method with Haldane's modification for small numbers and D prime (D′) was calculated to assess the level of linkage disequilibrium (LD) between the ten polymorphisms.

results  No differences in allele or genotype frequencies were observed between GD cases and control subjects for any of the nine SNPs studied. The S allele of the PolyA microsatellite marker was slightly more frequent in GD cases when compared with control subjects (χ2= 4·364, P = 0·04). Strongest LD between markers was observed towards the 3′ end of the VDR gene but there was no evidence of association with disease.

conclusion  This is the largest and most comprehensive study of the VDR gene in GD to date and these data suggest that these polymorphisms of the VDR gene do not contribute to GD susceptibility in the UK.
Plasma homocysteine in polycystic ovary syndrome: does it correlate with insulin resistance and ethnicity?
Authors: Wijeyaratne Chandrika N. , Nirantharakumar K , Balen Adam H. , Barth Julian H. , Sheriff Rezvi , Belchetz Paul E.
Published: December 2004

background  Polycystic ovary syndrome (PCOS) is associated with insulin resistance and premature coronary artery disease (CAD). Hyperhomocysteinaemia is a recognized risk factor for atherosclerosis, particularly among migrant South Asians, and has recently been shown to be correlated positively with the degree of insulin resistance/hyperinsulinaemia.

objectives  To compare total plasma homocysteine (Hcy) in PCOS with controls from ethnic groups at high and low risk of insulin resistance.

methods  Case control study of three ethnic groups, Sri Lankans (SL), British Asians (BA) and white Europeans (C), with and without PCOS at specialist centres in Sri Lanka and Yorkshire, UK. Fasting total plasma Hcy concentration was analysed by fluorescence polarization immunoassay and examined for any correlation with age, body mass index (BMI), central obesity, fasting insulin and insulin sensitivity [calculated by the Quantitative Insulin Sensitivity Check Index (QUICKI) method], lipids and testosterone in each ethnic group.

results  Eighty SL with PCOS and 45 controls, 47 BA with PCOS and 11 controls, and 40 C with PCOS and 22 controls were studied. Both Asian groups with PCOS were younger than affected Europeans (P = 0·008). Sri Lankans with PCOS had significantly lower BMI values than other affected groups: mean ± SEM (SL) 26·3 ± 0·95; (BA) 30·59 ± 7·54; (C) 32·1 ± 5·95 kg/m2 (P = 0·006). However, waist : hip ratios (WHR) of Sri Lankans with PCOS were similar to others: mean ± SEM (SL) 0·97 ± 0·01 (BA) 1·04 ± 0·02 (C) 0·92 ± 0·01, P = 0·33. Mean plasma Hcy was significantly higher in all PCOS groups than in their ethnically matched controls (Student's t‐test): (SL) 10·2 ± 1·9 vs 9·0 ± 3·8, P = 0·01; (BA) 7·9 ± 1·9 vs 6·8 ± 2·5, P < 0·0001; (C) 8·3 ± 2·3 vs 6·8 ± 1·5, P = 0·0007 µmol/l. Sri Lankans with PCOS had significantly greater Hcy concentrations than British Asians and Europeans with PCOS [P = 0·001; single‐factor analysis of variance (anova)] and also significantly greater fasting insulin concentrations [(SL) 242·9 ± 38·9; (BA) 89·4 ± 8·9; (C) 48·6 ± 4·8 pmol/l (P = 0·0003)] and significantly lower QUICKI [(SL) 0·308 ± 0·004; (BA) 0·335 ± 0·005; (C) 0·375 ± 0·002 (P = 0·0007)]. Fasting plasma Hcy correlated best with fasting insulin (r = 0·56, P = 0·0001) and QUICKI (r =−0·53, P < 0·0001) in Sri Lankans with PCOS. Hcy in PCOS subjects from all three ethnic groups correlated significantly with fasting insulin following adjustment for age, BMI and WHR (r = 0·45, P = 0·0001), but this was not evident in the controls (r =−0·32, P = 0·1).

conclusions  Elevation of fasting plasma homocysteine in PCOS varies with ethnicity and correlates significantly with fasting insulin. High homocysteine in young Sri Lankans with PCOS has major implications for their long‐term risk for atherosclerosis.
Long‐term skeletal effects of recombinant human growth hormone (rhGH) alone and rhGH combined with alendronate in GH‐deficient adults: a seven‐year follow‐up study
Authors: Biermasz Nienke R. , Hamdy Neveen A. T. , Pereira Alberto M. , Romijn Johannes A. , Roelfsema Ferdinand
Published: December 2004

background  GH‐deficient patients respond to recombinant human GH (rhGH) replacement therapy by increasing bone mineral density (BMD) at a rate of about 1% a year for at least 4 years. Predictive factors for a beneficial effect on bone are a low bone mass at baseline and gender. Whether the beneficial skeletal effects of GH are sustained in the long term remains to be established. It is also not known whether osteoporotic GH‐deficient patients may require additional antiresorptive drugs and whether this treatment would be effective concomitantly with GH replacement.

design  We performed a long‐term, controlled study in 30 GH‐deficient adults: 15 with osteoporosis and 15 control subjects with low bone mass. All patients were treated with rhGH for at least 4 years; thereafter, 3 years of additional alendronate treatment was given to patients with osteoporosis, while controls continued on GH therapy alone. The GH dose was individualized to maintain an IGF‐I within the normal reference range for the duration of the study, and was equal between genders.

results  At the end of 4 years of rhGH replacement therapy, a significant increase in mean lumbar spine BMD was observed in both the osteoporosis group (3·6%) and the control group (7·0%), with no significant difference between groups. Males had a larger increase in BMD than females (P = 0·032). After 4 or 5 years of GH treatment patients with persisting osteoporosis received additional alendronate (10 mg/day) for 3 years. Lumbar spine BMD increased by 8·7% after 3 years (P = 0·001) vs 1·5% (P = NS) in the control group continuing on rhGH replacement alone. The alendronate effect was gender independent (P = 0·59). Mean bone area of the lumbar spine did not change in both groups for the duration of the study. Femoral neck BMD increased significantly in the osteoporosis group (3·5%) and was unchanged in the control group. Five osteoporotic GH‐deficient patients had a total of 12 vertebral fractures before start of alendronate. Only one of these patients developed two new vertebral fractures within the first year of treatment with alendronate.

conclusion  We observed a significant increase in lumbar spine BMD in the first 4 years of rhGH replacement. The effect of GH on bone was gender dependent, but not BMD dependent. After more than 4 years of GH replacement, BMD seemed to reach a plateau, at least as measured in the 3–4 years thereafter, as no significant increase was present in patients treated with GH alone. By contrast, alendronate rapidly augmented BMD and this effect was maintained for at least 3 years. These increases in BMD were associated with a low incidence of (vertebral) fractures. The long‐term use of GH does not preclude a beneficial effect of an additional antiresorptive agent in GH‐deficient patients with osteoporosis.
Distribution pattern of somatostatin and cortistatin mRNA in human central and peripheral tissues
Authors: Dalm Virgil A. S. H. , Van Hagen P. Martin , De Krijger Ronald R. , Kros Johan M. , Van Koetsveld Peter M. , Van Der Lely Aart‐Jan , Lamberts Steven W. J. , Hofland Leo J.
Published: December 2004

background  Somatostatin receptors (sst) and their endogenous ligand, somatostatin (SS), are widely expressed throughout the human body. Recently, the cDNA of a novel SS‐like peptide, named cortistatin (CST), has been cloned. This CST was found to be expressed in more restricted areas, like brain cortex, testes, kidney, stomach and leucocytes. Further studies demonstrated a selective expression of CST in tissues and cells of the human immune system, while SS was not expressed.

objective  In the present study we investigated the expression pattern of both SS mRNA and CST mRNA in various human central and peripheral tissues by quantitative RT–PCR (Q–PCR), in order to evaluate whether CST is more widely expressed in man than described to date and to investigate the relationship between SS and CST expression levels in various tissues. Previously, two different CST mRNA isoforms have been described. Therefore, we investigated the expression of both isoforms by RT–PCR in the different tissues as well.

results  We demonstrate for the first time that CST mRNA is widely expressed in the human body. Interestingly, a selective expression of CST mRNA and not SS mRNA was only found in isolated cells of the human immune system, whereas different tissues expressed both SS and CST mRNA.

conclusion  CST may have a broader functional role than previously assumed.
Effects of recombinant LH (rLH) supplementation during controlled ovarian hyperstimulation (COH) in normogonadotrophic women with an initial inadequate response to recombinant FSH (rFSH) after pituitary downregulation
Authors: De Placido G. , Alviggi C. , Mollo A. , Strina I. , Ranieri A. , Alviggi E. , Wilding M. , Varricchio M. T. , Borrelli A. L. , Conforti S.
Published: December 2004

background  This study was aimed to evaluate the effect of different recombinant LH (rLH) doses on the ovarian outcome of normogonadotrophic women with an initial inadequate response to recombinant FSH (rFSH) after pituitary downregulation.

methods  Only women undergoing a ‘long protocol’ with a GnRH‐agonist followed by rFSH administration were enrolled. On the eighth day of stimulation, 46 patients with serum E2 levels < 180 pg/ml and with no follicle > 10 mm were randomized in two groups to receive a supplementation with a daily rLH dose of 75 (group A) or 150 IU (group B), respectively. Forty‐six normal responders continuing their monotherapy with rFSH formed the control group (C).

results  The mean number of oocytes retrieved and the percentage of mature oocytes in the group B (9·65 ± 2·16, 79·0%) were comparable with those observed in the group C (10·65 ± 2·8, 82·5%) and significantly higher when compared with the group A (6·39 ± 1·53, 65·7%). The mean number of ampoules of rLH was significantly higher in the group B (14·4 ± 2·0 vs. 9·65 ± 1·1), whereas these patients received a significantly lower mean number of rFSH ampoules (44·6 ± 7·4 vs. 36·1 ± 3·8). Seven (30·4%), 9 (39·1%) and 22 (47·8%) pregnancies were achieved in the groups A, B and C, respectively.

conclusions  These results suggest that patients with initial inadequate responses to rFSH after pituitary downregulation benefit from the addition of a daily dose of 150 IU of rLH, starting from the eighth day of stimulation.
Association of carotid arterial distensibility with Doppler indices of left ventricular filling in 50‐year‐old subjects
Authors: Kangro T. , Jonason T. , Henriksen E. , Ringqvist I.
Published: December 2004

Doppler indices of left ventricular diastolic filling are associated with various cardiac and extracardiac factors. Afterload is one of the extracardiac factors influencing left ventricular diastolic filling. The distensibility of the great arteries is one of the components of afterload. In this study, the relation between Doppler indices of left ventricular filling and the distensibility of the common carotid arteries was investigated. We studied 237 subjects at 50 years of age with Doppler echocardiography and ultrasound examination of the common carotid arteries. The following Doppler indices of left ventricular filling were studied: peak early diastolic velocity E‐wave, peak atrial diastolic velocity A‐wave and early to atrial peak velocity ratio, E/A. Carotid arterial characteristics were: distensibility coefficient, carotid arterial diameter change in systole and fractional change in the carotid arterial diameter. The relation between Doppler indices of left ventricular filling and carotid arterial characteristics was assessed by univariate and multivariate regression analysis. There was a significant univariate, positive association between E/A ratio and carotid arterial distensibility (r = 0·27, P<0·001), carotid arterial systolic diameter change (r = 0·19, P<0·005) and fractional change of the carotid arterial diameter (r = 0·20, P<0·005). In multivariate analysis, E/A ratio was independently associated with carotid arterial distensibility (P<0·005), after adjusting for heart rate, body mass index and gender. Decreased carotid arterial distensibility was associated with a reduction in E/A ratio, suggesting that arterial distensibility may have an effect on left ventricular diastolic filling or that changes in the arterial elastic properties are associated with corresponding structural changes in the left ventricle.
The three S‐layer‐like homology motifs of the S‐layer protein SbpA of Bacillus sphaericus CCM 2177 are not sufficient for binding to the pyruvylated secondary cell wall polymer
Authors: Huber Carina , Ilk Nicola , Rünzler Dominik , Egelseer Eva M. , Weigert Stefan , Sleytr Uwe B. , Sára Margit
Published: December 2004

The S‐layer protein SbpA of Bacillus sphaericus CCM 2177 recognizes a pyruvylated secondary cell wall polymer (SCWP) as anchoring structure to the peptidoglycan‐containing layer. Data analysis from surface plasmon resonance (SPR) spectroscopy revealed the existence of three different binding sites with high, medium and low affinity for rSbpA on SCWP immobilized to the sensor chip. The shortest C‐terminal truncation with specific affinity to SCWP was rSbpA31‐318. Surprisingly, rSbpA31‐202 comprising the three S‐layer‐like homology (SLH) motifs did not bind at all. Analysis of the SbpA sequence revealed a 58‐amino‐acid‐long SLH‐like motif starting 11 amino acids after the third SLH motif. The importance of this motif for reconstituting the functional SCWP‐binding domain was further demonstrated by construction of a chimaeric protein consisting of the SLH domain of SbsB, the S‐layer protein of Geobacillus stearothermophilus PV72/p2 and the C‐terminal part of SbpA. In contrast to SbsB or its SLH domain which did not recognize SCWP of B. sphaericus CCM 2177 as binding site, the chimaeric protein showed specific affinity. Deletion of 213 C‐terminal amino acids of SbpA had no impact on the square (p4) lattice structure, whereas deletion of 350 amino acids was linked to a change in lattice type from square to oblique (p1).
The morphogenetic MreBCD proteins of Escherichia coli form an essential membrane‐bound complex
Authors: Kruse Thomas , Bork‐Jensen Jette , Gerdes Kenn
Published: December 2004

MreB proteins of Escherichia coli, Bacillus subtilis and Caulobacter crescentus form actin‐like cables lying beneath the cell surface. The cables are required to guide longitudinal cell wall synthesis and their absence leads to merodiploid spherical and inflated cells prone to cell lysis. In B. subtilis and C. crescentus, the mreB gene is essential. However, in E. coli, mreB was inferred not to be essential. Using a tight, conditional gene depletion system, we systematically investigated whether the E. coli mreBCD‐encoded components were essential. We found that cells depleted of mreBCD became spherical, enlarged and finally lysed. Depletion of each mre gene separately conferred similar gross changes in cell morphology and viability. Thus, the three proteins encoded by mreBCD are all essential and function in the same morphogenetic pathway. Interestingly, the presence of a multicopy plasmid carrying the ftsQAZ genes suppressed the lethality of deletions in the mre operon. Using GFP and cell fractionation methods, we showed that the MreC and MreD proteins were associated with the cell membrane. Using a bacterial two‐hybrid system, we found that MreC interacted with both MreB and MreD. In contrast, MreB and MreD did not interact in this assay. Thus, we conclude that the E. coli MreBCD form an essential membrane‐bound complex. Curiously, MreB did not form cables in cell depleted for MreC, MreD or RodA, indicating a mutual interdependency between MreB filament morphology and cell shape. Based on these and other observations we propose a model in which the membrane‐associated MreBCD complex directs longitudinal cell wall synthesis in a process essential to maintain cell morphology.
Analysis of Campylobacter jejuni capsular loci reveals multiple mechanisms for the generation of structural diversity and the ability to form complex heptoses
Authors: Karlyshev Andrey V. , Champion Olivia L. , Churcher Carol , Brisson Jean‐Robert , Jarrell Harold C. , Gilbert Michel , Brochu Denis , St Michael Frank , Li Jianjun , Wakarchuk Warren W. , Goodhead Ian , Sanders Mandy , Stevens Kim , White Brian , Parkhill Julian , Wren Brendan W. , Szymanski Christine M.
Published: December 2004

We recently demonstrated that Campylobacter jejuni produces a capsular polysaccharide (CPS) that is the major antigenic component of the classical Penner serotyping system distinguishing Campylobacter into >60 groups. Although the wide variety of C. jejuni serotypes are suggestive of structural differences in CPS, the genetic mechanisms of such differences are unknown. In this study we sequenced biosynthetic cps regions, ranging in size from 15 to 34 kb, from selected C. jejuni strains of HS:1, HS:19, HS:23, HS:36, HS:23/36 and HS:41 serotypes. Comparison of the determined cps sequences of the HS:1, HS:19 and HS:41 strains with the sequenced strain, NCTC11168 (HS:2), provides evidence for multiple mechanisms of structural variation including exchange of capsular genes and entire clusters by horizontal transfer, gene duplication, deletion, fusion and contingency gene variation. In contrast, the HS:23, HS:36 and HS:23/36 cps sequences were highly conserved. We report the first detailed structural analysis of 81‐176 (HS:23/36) and G1 (HS:1) and refine the previous structural interpretations of the HS:19, HS:23, HS:36 and HS:41 serostrains. For the first time, we demonstrate the commonality and function of a second heptose biosynthetic pathway for Campylobacter CPS independent of the pathway for lipooligosaccharide (LOS) biosynthesis and identify a novel heptosyltransferase utilized by this alternate pathway. Furthermore, we show the retention of two functional heptose isomerases in Campylobacter and the sharing of a phosphatase for both LOS and CPS heptose biosynthesis.
Rpc25, a conserved RNA polymerase III subunit, is critical for transcription initiation
Authors: Zaros Cécile , Thuriaux Pierre
Published: December 2004

Rpc25 is a strongly conserved subunit of RNA polymerase III with homology to Rpa43 in RNA polymerase I, Rpb7 in RNA polymerase II and the archaeal RpoE subunit. A central domain of Rpc25 can replaced the corresponding region of Rpb7 with little or no growth defect, underscoring the functional relatedness of these proteins. Rpc25 forms a heterodimer with Rpc17, another conserved component of RNA polymerase III. A conditional mutant (rpc25‐S100P) impairs this interaction. rpc25‐S100P and another conditional mutant obtained by complementation with the Schizosaccharomyces pombe subunit (rpc25‐Sp) were investigated for the properties of their purified RNA polymerase III. The mutant enzymes were defective in the specific synthesis of pre‐tRNA transcripts but acted at a wild‐type level on poly[d(A‐T)] templates. They were also indistinguishable from wild type in transcript elongation, cleavage and termination. These data indicate that Rpc25 is needed for transcription initiation but is not critical for the elongating properties of RNA polymerase III.
Distinct segregation dynamics of the two Vibrio cholerae chromosomes
Authors: Fogel Michael A. , Waldor Matthew K.
Published: December 2004

The study of prokaryotic chromosome segregation has focused primarily on bacteria with single circular chromosomes. Little is known about segregation in bacteria with multipartite genomes. The human diarrhoeal pathogen Vibrio cholerae has two circular chromosomes of unequal sizes. Using static and time‐lapse fluorescence microscopy, we visualized the localization and segregation of the origins of replication of the V. cholerae chromosomes. In all stages of the cell cycle, the two origins localized to distinct subcellular locations. In newborn cells, the origin of chromosome I (oriCIvc) was located near the cell pole while the origin of chromosome II (oriCIIvc) was at the cell centre. Segregation of oriCIvc occurred asymmetrically from a polar position, with one duplicated origin traversing the length of the cell towards the opposite pole and the other remaining relatively fixed. In contrast, oriCIIvc segregated later in the cell cycle than oriCIvc and the two duplicated oriCIIvc regions repositioned to the new cell centres. DAPI staining of the nucleoid demonstrated that both origin regions were localized to the edge of the visible nucleoid and that oriCIvc foci were often associated with specific nucleoid substructures. The differences in localization and timing of segregation of oriCIvc and oriCIIvc suggest that distinct mechanisms govern the segregation of the two V. cholerae chromosomes.
Exploring prokaryotic diversity: there are other molecular worlds
Authors: Fernández Luis Angel
Published: December 2004

Prokaryotes are the major source of biological diversity on earth. This is not simply because of the large number of species present, or because of their diverse growth conditions and environmental niches populated by them, but because of the wealth of genes, metabolic pathways and molecular processes that are only found in prokaryotic cells. Therefore, Bacteria and Archaea (and their phages) cannot be considered any longer as miniaturized models of Eukaryotes, but as a genuine source of unique biological processes that are mediated by unique sets of genes and molecular devices. A true understanding of complex biological phenomena will require a deeper knowledge of this vast prokaryotic world. The second European Molecular Biology Organization (EMBO) conference on Molecular Microbiology entitled ‘Exploring Prokaryotic Diversity’ explored many aspects of this newly emerging interest in the prokaryotic world.
Differential ability of σs and σ70 of Escherichia coli to utilize promoters containing half or full UP‐element sites
Authors: Typas Athanasios , Hengge Regine
Published: December 2004

The σs subunit of RNA polymerase (RNAP) is the master regulator of the general stress response in Escherichia coli. Nevertheless, the selectivity of promoter recognition by the housekeeping σ70‐containing and σ5‐containing RNAP holoenzymes (Eσ70 and Eσs respectively) is not yet fully clarified, as they both recognize nearly identical −35 and −10 promoter consensus sequences. In this study, we show that in a subset of promoters, Eσs favours the presence of a distal UP‐element half‐site, and at the same time is unable to take advantage of a proximal half‐site or a full UP‐element. This is reflected by the frequent occurrence of distal UP‐element half‐sites in natural σs‐dependent promoters and the absence of proximal half‐sites. Eσ70, however, exhibits the opposite preference. The presence of the −35 element is a prerequisite for this differential behaviour. In the absence of the −35 element, half or full UP‐element sites play no role in sigma selectivity, but the distal subsite leads to an equivalent, if not greater, transcriptional stimulation than the proximal one for both sigma factors. Finally, experiments using single amino acid substitutions of σs indicate that the foundation for this preference lies in an inability of σs to interact with the a subunit C‐terminal domain.
Disulphide trapping of an in vivo energy‐dependent conformation of Escherichia coli TonB protein
Authors: Ghosh Joydeep , Postle Kathleen
Published: December 2004

In Escherichia coli, the TonB system transduces the protonmotive force (pmf) of the cytoplasmic membrane to support a variety of transport events across the outer membrane. Cytoplasmic membrane proteins ExbB and ExbD appear to harvest pmf and transduce it to TonB. Experimental evidence suggests that TonB shuttles to the outer membrane, apparently to deliver conformationally stored potential energy to outer membrane transporters. In the most recent model, discharged TonB is then recycled to the cytoplasmic membrane to be re‐energized by the energy coupling proteins, ExbB/D. It has been suggested that the carboxy‐terminal 75 amino acids of active TonB could be represented by the rigid, strand‐exchanged, dimeric crystal structure of the corresponding fragment. In contrast, recent genetic studies of alanine substitutions have suggested instead that in vivo the carboxy‐terminus of intact TonB is dynamic and flexible. The biochemical studies presented here confirm and extend those results by demonstrating that individual cys substitution at aromatic residues in one monomeric subunit can form spontaneous dimers in vivo with the identical residue in the other monomeric subunit. Two energized TonBs appear to form a single cluster of 8–10 aromatic amino acids, including those found at opposite ends of the crystal structure. The aromatic cluster requires both the amino‐terminal energy coupling domain of TonB, and ExbB/D (and cross‐talk analogues TolQ/R) for in vivo formation. The large aromatic cluster is detected in cytoplasmic membrane‐, but not outer membrane‐associated TonB. Consistent with those observations, the aromatic cluster can form in the first half of the energy transduction cycle, before release of conformationally stored potential energy to ligand‐loaded outer membrane transporters. The model that emerges is one in which, after input of pmf mediated through ExbB/D and the TonB transmembrane domain, the TonB carboxy‐terminus can form a meta‐stable high‐energy conformation that is not represented by the crystal structure of the carboxy‐terminus.
The TyrR regulon
Authors: Pittard James , Camakaris Helen , Yang Ji
Published: December 2004

The TyrR protein of Escherichia coli can act both as a repressor and as an activator of transcription. It can interact with each of the three aromatic amino acids, with ATP and, under certain circumstances, with the C‐terminal region of the α‐subunit of RNA polymerase. TyrR protein is a dimer in solution but in the presence of tyrosine and ATP it self‐associates to form a hexamer. Whereas TyrR dimers can, in the absence of any aromatic amino acids, bind to certain recognition sequences referred to as ‘strong TyrR boxes’, hexamers can bind to extended sequences including lower‐affinity sites called ‘weak TyrR boxes’, some of which overlap the promoter. There is no single mechanism for repression, which in some cases involves exclusion of RNA polymerase from the promoter and in others, interference with the ability of bound RNA polymerase to form open complexes or to exit the promoter. When bound to a site upstream of certain promoters, TyrR protein in the presence of phenylalanine, tyrosine or tryptophan can interact with the α‐subunit of RNA polymerase to activate transcription. In one unusual case, activation of a non‐productive promoter is used to repress transcription from a promoter on the opposite strand. Regulation of individual transcription units within the regulon reflects their physiological function and is determined by the position and nature of the recognition sites (TyrR boxes) associated with each of the promoters. The intracellular levels of the various forms of the TyrR protein are also postulated to be of critical importance in determining regulatory outcomes. TyrR protein remains a paradigm for a regulator that is able to interact with multiple cofactors and exert a range of regulatory effects by forming different oligomers on DNA and making contact with other proteins. A recent analysis identifying putative TyrR boxes in the E. coli genome raises the possibility that the TyrR regulon may extend beyond the well‐characterized transcription units described in this review.
Cell size and nucleoid organization of engineered Escherichia coli cells with a reduced genome
Authors: Hashimoto Masayuki , Ichimura Toshiharu , Mizoguchi Hiroshi , Tanaka Kimie , Fujimitsu Kazuyuki , Keyamura Kenji , Ote Tomotake , Yamakawa Takehiro , Yamazaki Yukiko , Mori Hideo , Katayama Tsutomu , Kato Jun‐ichi
Published: December 2004

The minimization of a genome is necessary to identify experimentally the minimal gene set that contains only those genes that are essential and sufficient to sustain a functioning cell. Recent developments in genetic techniques have made it possible to generate bacteria with a markedly reduced genome. We developed a simple system for formation of markerless chromosomal deletions, and constructed and characterized a series of large‐scale chromosomal deletion mutants of Escherichia coli that lack between 2.4 and 29.7% of the parental chromosome. Combining deletion mutations changes cell length and width, and the mutant cells with larger deletions were even longer and wider than the parental cells. The nucleoid organization of the mutants is also changed: the nucleoids occur as multiple small nucleoids and are localized peripherally near the envelope. Inhibition of translation causes them to condense into one or two packed nucleoids, suggesting that the coupling of transcription and translation of membrane proteins peripherally localizes chromosomes. Because these phenotypes are similar to those of spherical cells, those may be a consequence of the morphological change. Based on the nucleoid localization observed with these mutants, we discuss the cellular nucleoid dynamics.