bluuebunny/crossref_metadata_2025 huggingface dataset:
Age- and sex-related resistance to chronic experimental autoimmune myasthenia gravis (EAMG) in Brown Norway rats
Authors: Hoedemaekers A , Graus Y , Van Breda Vriesman P , De Baets M
Published: November 2003

The influence of age and sex on the induction of chronic EAMG was analysed. Aged male rats, immunized with Torpedo acetylcholine receptor (tAChR), showed no clinical signs of disease or AChR loss. Immunization of young male Brown Norway (BN) rats resulted in both clinical signs of disease and 65% AChR loss. In contrast, both young and aged female BN rats showed comparable AChR loss (58% and 50%, respectively), although aged female rats did not develop clinical signs of disease. Differences in antibody titres, isotype distribution, fine specificity or complement activation could not account for the observed resistance. These results suggest that resistance against EAMG in aged rats is due to resistance of the AChR against antibody-mediated degradation, or to mechanisms able to compensate for AChR loss.
Hepatitis C virus (HCV)-induced IgG-IgM rheumatoid factor (RF) complex may be the main causal factor for cold-dependent activation of complement in patients with rheumatic disease
Authors: Wei G , Yano S , Kuroiwa T , Hiromura K , Maezawa A
Published: November 2003

A low serum complement level is commonly found in patients with rheumatic diseases. We evaluated 170 patients with such diseases to determine their serum levels of CH50, C3 and C4 protein. Persistent hypocomplementaemia was found in 19 of those patients, particularly in those with systemic lupus erythematosus (SLE). Cold-dependent activation of complement (CDAC) was demonstrated in nine of the 19 (47.4%), and six of the nine patients demonstrated infection with HCV (66.7%). The nine patients that exhibited CDAC had nearly normal haemolytic complement activity when the sera were separated either at 37°C or in EDTA-treated plasma. Conversely, it markedly decreased, even to the point of being immeasurable, when the sera were separated at 4–21°C. No significant deficiency in C3 and C4 protein levels was found in these patients. Clinical parameters other than levels of anti-HCV antibody, transaminase, and RF were not influenced by CDAC. In an attempt to isolate the causal factor for CDAC, we isolated IgG fractions from the CDAC patients by using a protein G column, in which case precipitates were collected from the eluates. The precipitates were mixed with normal serum and incubated at 4–21°C for 18 h. A decrease in the level of CH50 in normal serum was observed, which predominated (P<0.001) when precipitates from HCV-infected patients were used. This indicated CDAC was possibly interrelated to the precipitates of such patients. This precipitate was proved to contain IgM besides IgG. It is therefore possible that an HCV-related IgG complex or an IgG-IgM RF complex may be formed at low temperature and be involved in activating the complement system in vitro.
IL-6 and soluble IL-6 receptors (sIL-6R and sgp130) in human pleural effusions: massive IL-6 production independently of underlying diseases
Authors: Doré P , Lelièvre E , Morel F , Brizard A , Fourcin M , Clément C , Ingrand P , Daneski L , Gascan H , Wijdenes J , Gombert J , Preud'Homme J L , Lecron J C
Published: November 2003

IL-6, soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130) levels were measured in sera and pleural effusions from 42 patients with metastatic carcinoma, non-Hodgkin's lymphoma, tuberculosis, cardiac failure and miscellaneous diseases. Pleural IL-6 levels measured by ELISA were very high in all patient groups (mean 34.8 ± 15.3 ng/ml) without significant difference according to diseases. IL-6 was shown to be biologically active in a proliferative assay. Serum IL-6 levels were low (0.049 ± 0.014 ng/ml) and did not correlate with pleural fluid levels. Pleural IL-6 levels correlated with the number of polymorphonuclear cells in pleural fluid (P < 0.03). Pleural sIL-6R levels (76 ± 8 ng/ml) were always lower than serum levels (196 ± 12 ng/ml; P < 0.0001) but correlated with them (P < 0.01). Pleural sIL-6R and albumin levels correlated (P < 0.01), suggesting a transudation of sIL-6R from the serum. Pleural sgp130 levels (10.9 ± 1.0 ng/ml) were lower than serum levels (24.6 ± 2.8 ng/ml; P < 0.002). After gel filtration of pleural fluid, the bulk of IL-6 (>90%) was recovered in a 15 000–30 000 fraction, corresponding to the expected mol. wt of free IL-6. These results suggest a production and a sequestration of IL-6 in the pleural cavity in all studied conditions.
Dynamic expression of transforming growth factor-betas (TGF-β) and their type I and type II receptors in the synovial tissue of arthritic rats
Authors: Müssener Å , Funa K , Kleinau S , Klareskog L
Published: November 2003

A well characterized animal model that shares many characteristic features with rheumatoid arthritis (RA) is collagen-induced arthritis (CIA) in DA rats. Recent studies have demonstrated that TGF-β, a multifunctional cytokine, is an important modulator of the immune response in CIA, and possibly also in RA. In this study we have investigated the expression of the precursor forms of TGF-β1, TGF-β2, TGF-β3, as well as TGF-β type I receptor (TGF-βRI) and TGF-β type II receptor (TGF-βRII) in the synovial tissue of arthritic rats during the course of the disease. By using immunohistochemical techniques, an abundant expression of all three TGF-β isoforms and their receptors was observed in the arthritic synovia, an expression that increased with time after onset of disease. Antibodies to TGF-β1, TGF-β2, TGF-βRI and TGF-βRII stained blood vessels intensively, already at the early onset of inflammation, whereas the synovial lining layer and chondrocytes expressed strong immunoreactivity later on in the inflammatory process. The most intense staining with these antibodies was detected in fibroblasts within fibrotic tissue, in particular at the cartilage–pannus junction. Interestingly, TGF-β3 only stained macrophage-like cells and chondrocytes in the synovia. The data suggest that the abundant expression of TGF-β1, TGF-β2, TGF-β3 as well as TGF-βRI and TGF-βRII in the synovia, is of pathogenic importance in the development of CIA, although the question of how the different TGF-β isoforms may enhance or counteract different arthritogenic events remains open.
In contrast to their murine counterparts, normal human keratinocytes and human epidermoid cell lines A431 and HaCaT fail to express IL-10 mRNA and protein
Authors: Teunissen M B M , Koomen C W , Jansen J , De Waal Malefyt R , Schmitt E , Van Den Wijngaard R M J G J , Das P K , Bos J D
Published: November 2003

In mice, keratinocyte-derived IL-10 is up-regulated by ultraviolet-B (UVB) radiation and plays a major role in UVB-induced immunosuppression. The present study was designed to examine whether a comparable phenomenon can be detected in man. Freshly isolated or cultured normal human keratinocytes (NHK) and keratinocyte cell lines A431 and HaCaT were stimulated with graded doses of UVB (up to 200 J/m2) or with a variety of other stimuli. RNA was extracted at various time points post-stimulation and analysed by reverse transcriptase-polymerase chain reaction (RT-PCR) using four different IL-10-specific primer pairs and RNA from monocytes or T cells as positive controls. We failed to detect IL-10 mRNA in NHK from 40 different donors (breast, abdomen, leg, scalp, foreskin) and in A431 and HaCaT cells, irrespective of the stimulation used and despite successful stimulation. Supernatants of NHK, A431 and HaCaT cultures were negative for IL-10 protein, as tested by four different ELISAs and a bioassay. Murine keratinocytes, stimulated under comparable conditions and tested by the same techniques, displayed a strong expression of IL-10 mRNA and protein. Remarkably, an IL-10 mRNA signal could be detected in NHK after a second round of PCR amplification. Because NHK suspensions are contaminated with Langerhans cells, melanocytes and possibly fibroblasts, we tested pure populations of each individual cell type to determine the origin of this IL-10 mRNA. Our results clearly indicate that NHK, Langerhans cells and fibroblasts fail to express IL-10 and that melanocytes are the principal source of IL-10 mRNA in normal human epidermis.
Modulation of lymphocyte and monocyte activity after intravenous immunoglobulin administration in vivo
Authors: Aukrust P , Muüller F , Nordøy I , Haug C J , Frøland S S
Published: November 2003

In 12 patients with primary hypogammaglobulinaemia we investigated the in vivo effect of one bolus injection (400 mg/kg) of intravenous immunoglobulin (IVIG) on lymphocyte subsets and monocytes in peripheral blood, on plasma levels of soluble factors reflecting monocyte and lymphocyte activity and on lymphocyte proliferation and generation of reactive oxygen species (ROS) from monocytes analysed in vitro. Several immunological changes were induced by IVIG infusion. First, there was a significant decrease in CD4+/CD8+ lymphocyte ratio in peripheral blood, reflecting a significant increase in circulating numbers of CD8+ lymphocytes. Second, although there was no significant change in plasma levels of soluble CD8 antigen, there was a significant decrease in soluble CD8 antigen/CD8+ lymphocyte ratio, suggesting a down-regulation of CD8+ lymphocyte activity. Third, there was a significant increase in plasma levels of neopterin, suggesting in vivo activation of monocytes/macrophages. Fourth, the was a down-modulation of mitogen-stimulated lymphocyte proliferation in vitro, and this down-regulation was significantly correlated with the increase in plasma neopterin levels. Finally, there was a significant decrease in zymosan-stimulated, but not in phorbol myristate acetate-stimulated, ROS generation from monocytes as evaluated by nitroblue tetrazolium reduction. The ability of IVIG administration in vivo to down-modulate lymphocyte proliferation and ROS generation from monocytes in patients with persistent immune activation may be relevant for the clinical effects of IVIG in a variety of immune-mediated disorders.
Increased IL-6 and IL-8 in bronchoalveolar lavage fluids (BALF) from patients with sarcoidosis: correlation with the clinical parameters
Authors: Takizawa H , Satoh M , Okazaki H , Matsuzaki G , Suzuki N , Ishii A , Suko M , Okudaira H , Morita Y , Ito K
Published: November 2003

A variety of cytokines have been implicated in the pathogenesis of pulmonary sarcoidosis, but the exact roles of IL-6 and IL-8 are not yet clear. We studied these cytokine levels in BALF from patients with pulmonary sarcoidosis, idiopathic pulmonary fibrosis (IPF), systemic screlosis (SSc) with interstitial lung disease and control subjects. IL-6 and IL-8 levels were significantly elevated in sarcoidosis, IPF and SSc with interstitial lung disease compared with control subjects. Subjects with sarcoidosis had significantly increased levels of both cytokines compared with controls when the cytokine values were corrected by the total albumin content and the two cytokine levels correlated with each other (r=0.876). BALF IL-6 levels correlated with percent lymphocytes and percent CD3+ cells. Moreover, when sarcoidosis patients were divided into three groups, those who needed steroid therapy or had progressive disease showed increased cytokine levels in BALF over stable or improved patients. These observations suggest that locally derived IL-6 and IL-8 were increased in sarcoidosis and correlated with activity of this granulomatous lung disease.
Progression of HIV disease is associated with increased expression of FcγRI and CR1 on alveolar macrophages
Authors: Gilbody J , Lipman M C I , Johnson M A , Atkins M , Poulter L W
Published: November 2003

The expression of receptors for complement and the Fc region of immunoglobulin by alveolar macrophages (AM) constitutes a valuable aid to effector function of these cells. However, during HIV infection such expression may also act to increase binding of immune complexes, thus facilitating viral infection of these cells. This study was designed to determine whether changes in the expression of these receptors occurs in situ during HIV infection. Lung macrophages were isolated by bronchoalveolar lavage in groups of HIV+ subjects segregated on the basis of peripheral CD4 count. A group of normal subjects was also investigated. Expression of CR1 and FcγRI was quantified by measuring the optical density of reaction product following controlled immunoperoxidase staining with MoAbs CD35 and CD64. Both CR1 and FcγRI were increased over normal in all HIV+ subjects. This increase was progressive with advancing disease as determined by correlation with declining peripheral CD4 count. Comparison of asymptomatic and symptomatic subjects with HIV infection showed no difference in CR1 expression but a rise in FcγRI expression in the latter group. An overall inverse correlation was also found between peripheral CD4 count and FcγRI expression, but not CR1 expression. These data demonstrate a significant increase in the expression of these receptors on AM from HIV+ subjects, and show that this increase may occur before any symptoms in these patients.
The effect of repeated administration of hexarelin, a growth hormone releasing peptide, and growth hormone releasing hormone on growth hormone responsivity
Authors: Massoud Ahmed F. , Hindmarsh Peter C. , Matthews David R. , Brook Charles G. D.
Published: November 2003

OBJECTIVE Hexarelin is a synthetic six‐amino‐acid compound capable of releasing GH in animals and in man. Its mechanism of action is not understood and little is known about the GH response after repeated administration. The aim of this study was to determine the GH response to the administration of two intravenous boluses of hexarelin, growth hormone releasing hormone (GHRH) or hexarelin with GHRH.

DESIGN Single boluses of hexarelin (1 μg/kg), GHRH‐(1–29)‐NH2 (1 μg/kg) or hexarelin with GHRH‐(1–29)‐NH2 were administered intravenously. Each study was performed on two further occasions, with a second bolus being administered 60 or 120 minutes after the first. A control study was performed giving saline intravenously. Studies were performed in a random order.

SUBJECTS Six healthy adult males (25.4–34.1 years) were studied.

MEASUREMENTS Serum GH was measured by radioimmunoassay. GH secretion rates were derived from the measured serum GH concentrations using the technique of deconvolution analysis.

RESULTS The peak GH secretion rate following the first intravenous bolus of hexarelin was greater than that following the first bolus of GHRH‐(1–29)‐NH2 (P < 0.001), and was greatest following the administration of hexarelin with GHRH‐(1–29)‐NH2 (P < 0.001). The coadministration of the two secretagogues resulted in peak GH secretion rates significantly greater than the arithmetic sum of those following their isolated administration (P = 0.001), demonstrating synergism. Compared to saline, the administration of a second bolus of hexarelin, GHRH‐(1–29)‐NH2 or both resulted in significant further GH secretion (P = 0.02, P = 0.002, P = 0.03, respectively).

The administration of a second bolus of hexarelin or hexarelin with GHRH‐(1–29)‐NH2 120 minutes after the first bolus resulted in lower peak GH secretion rates (P = 0.03). The reductions in peak GH secretion rates following the 60‐minute boluses were not statistically significant. The peak GH secretion rates following the first GHRH‐(1–29)‐NH2 boluses were similar to those following the 60 and 120‐minute GHRH‐(1–29)‐NH2 boluses (P = NS). Irrespective of the interval between the boluses of hexarelin with GHRH‐(1–29)‐NH2, the peak GH secretion rates following the second boluses were not significantly different from the arithmetic sum of those following the administration of the second boluses of hexarelin or GHRH‐(1–29)‐NH2, indicating loss of synergism on repeated administration.

CONCLUSIONS This study shows that hexarelin is a potent GH secretagogue active after two successive doses; the magnitude of the GH response to the second dose was influenced by the dosing interval. Hexarelin and GHRH‐(1–29)‐NH2 are synergistic, a property which is lost after repeated administration. These findings may help our understanding of GHRPs and may have implications for the potential use of hexarelin and other GHRPs as therapeutic agents.
Specific stimulation of brain serotonin mediated neurotransmission by dexfenfluramine does not restore growth hormone responsiveness in obese women
Authors: Kars Michael E. , Pijl Hanno , Cohen Adam F. , Frölich Marijke , Schoemaker Hendrik C. , Brandenburg Henry C. R. , Edo Meinders A.
Published: November 2003

OBJECTIVE Growth hormone release in response to all known stimuli of GH secretion is blunted in obese subjects. Several studies, using dl‐fenfluramine (dl‐FF) as a serotoninergic tool, suggest that brain serotonin plays a role in the pathogenesis of this phenomenon. However, the effect of dl‐FF appears to be dependent on the stimulus used to induce GH release. Furthermore, dl‐FF has catecholamingergic properties apart from its capacity to stimulate serotonin release and to block its re‐uptake. In this study, we investigated whether subchronic treatment with the highly selective serotoninergic drug dexfenfluramine (d‐FF) affects the GH response to galanin or GHRH in obese subjects.

DESIGN The study had a randomized, cross‐over, placebo controlled design. d‐FF was administered in a dose of 15 mg twice daily during 6 days. On days 5 and 6 of treatment (with either d‐FF or placebo) an i.v. bolus injection of 100 μg hGHRH(1‐44) or a continuous infusion of p‐galanin (40 pmol/kg/min over 40 minutes) were administered in randomized order. All tests were performed in the follicular phase of two consecutive menstrual cycles.

PATIENTS Eight obese women (body mass index (BMI) 34.5 ± 3.6 kg/m2); 7 normal weight (BMI 21.9 ± 1.9 kg/m2) age‐matched control women. All women had a regular menstrual cycle. None used oral contraceptive drugs.

MEASUREMENTS GH response to either stimulus was measured both during treatment with d‐FF and during treatment with placebo.

RESULTS The GH response to galanin and the response to GHRH were significantly smaller in obese subjects. d‐FF significantly reduced the galanin induced GH secretion in obese subjects, but not in normal weight controls. It did not significantly affect GH release in response to GHRH in either group.

CONCLUSION This study confirms that GH secretion in response to stimuli with varying mechanisms of action is blunted in obese subjects. A decrease of central serotonin mediated neurotransmission does not appear to play a role in the pathogenesis of this phenomenon.
Internal quality assurance in cervical cytology—one laboratory’s experience
Authors: CROSS P. A.
Published: November 2003

The results of an internal quality assurance exercise in one cervical cytology laboratory in England are presented, using differing types of partial percentage re‐screening of cervical smears. An overall false‐negative dyskaryotic rate of up to 4.3% was demonstrated, with the final cytology report diagnosis differing from the primary screening diagnosis in 1.3% of cases. These findings are discussed, with the aim of helping to foster debate on the setting of national laboratory internal quality assurance standards.
Cigarette smoking stimulates cysteinyl leukotriene production in man
Authors: Fauler J. , Frölich J. C.
Published: November 2003

Chronic cigarette smoking is an important risk factor for pulmonary and cardiovascular diseases. An increased production of cysteinyl leukotrienes has been shown in asthma and in cardiac ischaemia. The effect of cigarette smoking on cysteinyl leukotriene biosynthesis is, however, not known. Urinary leukotriene E4 (LTE4)was measured in 30 habitual smokers and in 30 non‐smokers. In a further 12 non‐smokers urinary LTE4 excretion was assessed before and after smoking six cigarettes. In addition, the effect of transdermal nicotine on urinary LTE4 excretion was studied in seven non‐smokers. There was a close correlation (r = 0.92, P < 0.0001) between urinary excretion of LTE4 and the number of cigarettes smoked daily by habitual smokers. Smoking six cigarettes within 12 h resulted in a significant (P = 0.0047), twofold increase in the mean individual LTE4 excretion in non‐smokers. Transdermal nicotine had no effect on LTE4 excretion in non‐smokers. In conclusion, cigarette smoke causes a dose‐related increase in cysteinyl leukotriene production in habitual smokers. Some of the adverse effects of smoking may be related to an enhanced leukotriene synthesis.
Post‐prandial metabolism of triglyceride‐rich lipoproteins in non‐insulin‐dependent diabetic patients before and after bezafibrate treatment
Authors: ATTIA N. , DURLACH V. , ROCHE D. , PAUL J.‐L. , SONI T. , ZAHOUANI A. , LANDRON F. , LABROUSSE F. , LEUTENEGGER M. , GIRARD‐GLOBA A.
Published: November 2003

Retarded post‐prandial (pp) lipid clearance is potentially a major component of the increased cardiovascular risk incurred by hypertriglyceridaemic non‐insulin‐dependent diabetic mellitus (NIDDM) patients. The effect of bezafibrate (Bz, 400 mg per day for 5 weeks on chylomicron (CM) and remnant clearance after loads of 100 g of fat and vitamin A was therefore explored in 10 male patients (glycaemia 11.9 ±3.3 TG 4.5 ±2.4 mmol L–1). In all subjects CM‐TG and retinyl palmitate (RP) were reduced by 50%, but 8‐h non‐CM (remnant) RP decreased only in initially mildly hypertriglyceridaemic subjects (−35%, P <0.05), while in three patients with very elevated initialTG (ε3/3, ε3/2 and ε2/2 genotypes) 8‐h remnant RP increased by 100%. The decrease in pp CM‐TG correlated with that of fasting Sf 20–400 (r = 0.686, P = 0.026), suggesting that improved lipolysis was a major determinant of hypolipidaemic effect. Apo CIII synthesis is known to be depressed by Bz: concentrations were lower under Bz (P <0.05). A positive correlation (r =0.880, P <0.001) with fasting TG before treatment and its disappearance after treatment suggested an involvement of high concentrations with hypertriglyceridaemia. Post‐prandial non‐esterified fatty acids were decreased by 35 in correlation with a significant (−19%, P <0.05) improvement in fasting glycaemia (r =‐.801, P <0.005). These results suggest that Bz acts both on lipolysis and on removal of CM remnants, but that removal can become saturated when lipolysis is massively improved.
Resting and stimulated human polymorphonuclear leucocytes from type‐2 diabetic patients: change in purine nucleotide pattern
Authors: Zappacosta B. , De Sole P. , Di Salvo S. , De Michele T. , Pennacchietti L. , Giardina B.
Published: November 2003

It is known that polymorphonuclear leucocytes are deeply involved in the inflammatory complications of diabetes mellitus, showing many functional and biochemical abnormalities. Because adenine and guanine metabolites exert an important role in many metabolic aspects of phagocytic cells, we have investigated the pattern of purine metabolites during the respiratory burst of polymorphonuclear leucocytes in order to characterize any difference that may be significantly correlated with the abnormal neutrophil function of diabetic patients. The results obtained show clearly that polymorphonuclear leucocytes from diabetic patients are characterized by an abnormal pattern of purine nucleotides and their metabolites. In particular, the concentration of adenine and guanine triphosphates and the net amount of adenosine triphosphate hydrolysed during neutrophil stimulation by phorbol ester is higher in diabetic than in control cells. Moreover, higher values of adenosine monophosphate, inosine monophosphate and inosine have been found in diabetic cells. The behaviour of guanosine triphosphate is highly interesting. In fact, in addition to the higher concentration found in diabetic polymorphonuclear leucocytes, stimulation by phorbol ester induces a net decrease in guanosine triphosphate whereas control neutrophils show a slight increase. These findings have been associated with the ease with which diabetic neutrophils undergo metabolic activation and sustain an inflammatory response.
Identification of functional GRP‐preferring bombesin receptors on human melanoma cells
Authors: Pansky A. , Peng F. , Eberhard M. , Baselgia L. , Siegrist W. , Baumann J. B. , Eberle A. N. , Beglinger C. , Hildebrand P.
Published: November 2003

Bombesin was originally isolated from amphibian skin, wherease its mammalian counterpart, gastrin‐releasing peptide (GRP), was first identified in the nervous system of the gastrointestinal tract. Whether GRP is present in the human skin is not known. Bombesin‐like peptides are also known to modulate growth. We therefore investigated whether human melanoma cell lines express functional GRP‐preferring bombesin receptors and whether they alter growth or other specific cellular functions of these tumour cells. GRP receptor mRNA was found in HBL, D‐10, Me‐28 and A375‐6 cell lines, but only A375‐6 cells express a large number of high‐affinity binding sites for [125I]‐[Tyr4] bombesin (Kd 0.31 ± 0.04 nmol L−1, 3880 ± 429 binding sites per cell). Bombesin dose‐dependently increased cytosolic calcium, but did not alter interleukin (IL) 1β‐induced reduction of cell viability or IL‐6 secretion, both A375‐6‐specific cell functions. Growth of A375‐6 cells was not altered by bombesin or the specific GRP receptor antagonist BIM26226 as measured by [3H]‐thymidine incorporation or methylene blue assay, whereas insulin alone or in combination with other potential growth factors dose‐dependently stimulated growth of these cells. The newly characterized GRP‐preferring bombesin receptors on highly malignant human melanoma cells could initiate studies of growth effects on solid tumours or in vivo scanning using radiolabelled tracers.
The consequences of clutch size for incubation conditions and hatching success in starlings
Authors: Reid J. M. , Monaghan P. , Ruxton G. D.
Published: November 2003

1. Starling (Sturnus vulgaris) clutches were manipulated so that sibling eggs were incubated within either natural‐sized clutches, or clutches that had been experimentally enlarged but were still within the natural range of variation. Thus the consequences of incubated clutch size for hatching success were investigated.

2. Eggs incubated within enlarged clutches hatched less successfully than eggs incubated within natural‐sized clutches, suggesting that clutch size affects the conditions experienced by embryos during incubation.

3. Eggs incubated in enlarged clutches may have hatched poorly because clutch enlargement altered nest microclimate, causing increased water loss during the incubation period.

4. There was no evidence that enlargement altered nest microclimate by energetically constraining parents from incubating effectively. Instead, intrinsic physical properties of enlarged clutches affected clutch temperature directly.

5. Parents that had incubated experimentally enlarged clutches subsequently fledged fewer chicks than control parents, suggesting that constraints imposed during incubation may influence the optimal number of eggs that parents should lay.

6. Future studies should investigate whether parents laying naturally large clutches can minimize the problems of incubating many eggs by adaptively tailoring the shape and composition of their eggs to their expected clutch size.
State‐dependent fertility in pinnipeds: contrasting capital and income breeders
Authors: Boyd I. L.
Published: November 2003

1. The study tested the hypothesis that the occurrence of pregnancy in mammals that are capital breeders will be most closely related to state variables that are indices of food stores. Income breeders would not be expected to have the same relationship.

2. The study examined the relationships between mass, time of year, age and body length with the occurrence of pregnancy in three species of pinniped. This included two capital breeders (Crabeater Seal, Lobodon carcinophagus Hombron & Jacquinot, and Grey Seal, Halichoerus grypus Fabricius) and one income breeder (Antarctic Fur Seal, Arctocephalus gazella Peters). Multiple logistic regression analysis was used to examine the relationships and the interactions between the different state variables.

3. In both the capital breeders the state variables used in the study explained approximately twice the amount of variability (55% compared with 25%) in the occurrence of pregnancy than in the income breeder. Mass was the dominant state variable among both the capital breeders whereas in the income breeder mass was less important both relative to other state variables and in absolute terms. The results support the conclusion that the occurrence of pregnancy in capital breeders is more sensitive to body reserves than it is in income breeders.

4. The results also support the conclusion that life histories are the end result of a variety of functional responses to different state variables that have differing degrees of influence. In particular a size‐structured approach to studies of population dynamics in pinnipeds may be a more informative way of predicting population responses to environmental variability than the more traditional age‐structured approach.
Particle feeding in Aphodius dung beetles (Scarabaeidae): old hypotheses and new experimental evidence
Authors: P. Holter
Published: November 2003

1. Published studies of the highly specialized mouthparts of adult scarabaeid dung beetles have proposed that the beetles feed on (1) liquid with minute particles, squeezed out of the dung by the mandibular molars, and/or (2) dung particles that are finely ground by the same molars. These hypotheses were tested experimentally.

2. The maximum size of ingested particles was determined in six Aphodius species (Scarabaeidae, Aphodiinae) feeding on dung with latex‐balls of known diameters. The probability of ingestion decreased with particle size. The diameter of balls with a 5% chance of ingestion varied between species from <5 µm to about 25 µm. This maximum size, which precludes hypothesis (1), was related to feeding habits, not to body mass.

3. Simple experiments did not indicate any comminution by the mouthparts of dung particles.

4. It is suggested that coarse (mostly indigestible) particles are rejected by filtering setae and that the remaining small particles, prior to ingestion, are concentrated on the molars by squeezing which eliminates superfluous water.

5. Since 40–50% of the dry matter in fresh dung from grazing cows, sheep and horses consisted of particles <20 µm, food competition among adult Aphodius seems unlikely in spite of their selective feeding.
Causes and consequences of mass loss upon predator encounter: feeding interruption, stress or fit‐for‐flight?
Authors: Veen I. T. Van Der , Sivars L. E.
Published: November 2003

1. Birds have been shown to lose mass upon predator encounters. This mass loss has generally been assumed to be caused by the feeding interruption the birds experience upon encountering the predator. However, birds may lose this mass because of predator stress and because they prepare themselves for flight (fit‐for‐flight). In this experiment the aim was to distinguish between effects of feeding interruptions and stress or fit‐for‐flight on the mass loss of Yellowhammers (Emberiza citrinella L.) upon predator exposure.

2. When exposed to a 45‐min feeding interruption, the birds lost only a quarter of the mass they lost when they were moved to another room and exposed to a stuffed Sparrowhawk (Accipiter nisus) for 1 min at that beginning of the feeding interruption. This indicates that mass loss upon predator exposure is not just due to the feeding interruption birds experience upon encountering a predator, but is probably, to a large extent, due to both predator stress and fit‐for‐flight.

3. When the stuffed Sparrowhawk was replaced with a dummy (an opaque plastic bottle), mass loss upon exposure was similar to the loss in the Sparrowhawk treatment. This indicates that moving the birds to another room, which occurred in both these treatments, may to a large extent be the cause of the mass loss.

4. During the same day, the birds regained 92% of their losses. However, regaining those losses was partly postponed to the end of the day, which indicates that the birds faced a trade‐off between starvation and predation risk, and were able to respond to that trade‐off by altering their diurnal trajectory of mass increase. By postponing foraging to the end of the day, the birds decreased the mass‐dependent costs of predation risk.
Functional interaction of Escherichia coli RNA polymerase with inorganic polyphosphate
Authors: Kusano Shuichi , Ishihama Akira
Published: November 2003

Background:

RNA polymerase from the stationary growth phase cells of Escherichia coli is tightly associated with an acidic compound(s) and exhibits altered promoter selectivity, with reduced transcriptional activity of the genes highly expressed in the exponentially growing cells. Here we have examined the nature of the RNA polymerase‐associated acidic compound(s).

Results:

RNA polymerase isolated from stationary‐phase cells of E. coli was found to be tightly associated with inorganic polyphosphates (poly P), and cannot be dissociated even after chromatography on phosphocellulose or DNA‐cellulose columns. Since RNA polymerase–poly P complexes reconstituted in vitro showed similar properties, poly P was not binding covalently. The inhibitory effects of poly P on transcription were examined using two forms of the holoenzyme, one containing σ70, the major σ for transcription of the genes expressed during exponential cell growth and the other containing σ38, the principal σ in the stationary growth phase. At low salt concentrations, poly P inhibited transcription by both Eσ70 and Eσ38 holoenzymes. With an increase in the concentration of potassium glutamate, the poly P inhibition was relieved. At high salt concentrations, the Eσ70 holoenzyme is not able to function, but the Eσ38 holoenzyme is however activated.

Conclusions:

These results show that poly P may play a role in the promoter selectivity control of RNA polymerase in E. coli which is growing under conditions of high osmolarity and in the stationary growth phase.
A globular complex formation by Nda1 and the other five members of the MCM protein family in fission yeast
Authors: Adachi Yasuhisa , Usukura Jiro , Yanagida Mitsuhiro
Published: November 2003

Background:

In the fission yeast Schizosaccharomyces pombe, Nda1, Nda4, Mis5 and Cdc21 proteins belong to the MCM (minichromosome maintenance) protein family which is thought to have six members. Each MCM member is required for the early stages of DNA replication, and has a well‐conserved central 200‐amino acid domain containing a putative ATP binding motif. However, the precise molecular functions of MCM proteins are not yet clear.

Results:

We investigated the physical interaction of Nda1 protein with the other fission yeast MCM proteins using specific antibodies. Immunoprecipitation of Nda1 protein leads to the co‐precipitation of all the other members of the fission yeast MCM protein family. We purified the MCM protein complex by a combination of column chromatography. The native molecular weight of the MCM complex was estimated by gel filtration to be 560 kDa. The purified fraction contained nearly equal quantities of the six MCM proteins. Electron microscope observation showed that the MCM complex has a globular shape with a central cavity.

Conclusions:

We have developed a procedure to purify fission yeast MCM proteins in a native hetero‐oligomeric complex form for the first time, which opens an avenue to further biochemical analysis.
Switching yeast from meiosis to mitosis: double‐strand break repair, recombination and synaptonemal complex
Authors: Zenvirth Drora , Loidl Josef , Klein Shoshana , Arbel Ayelet , Shemesh Ronen , Simchen Giora
Published: November 2003

Background:

When Saccharomyces cerevisiae cells that have begun meiosis are transferred to mitotic growth conditions (‘return‐to‐growth’, RTG), they can complete recombination at high meiotic frequencies, but undergo mitotic cell division and remain diploid. It was not known how meiotic recombination intermediates are repaired following RTG. Using molecular and cytological methods, we investigated whether the usual meiotic apparatus could repair meiotically induced DSBs during RTG, or whether other mechanisms are invoked when the developmental context changes.

Results:

Upon RTG, the rapid disappearance of meiotic features—double‐strand breaks in DNA (DSBs), synaptonemal complex (SC), and SC related structures—was striking. In wild‐type diploids, the repair of meiotic DSBs during RTG was quick and efficient, resulting in homologous recombination. Kinetic analysis of double‐strand breakage and recombination indicated that meiotic DSB formation precedes the commitment to meiotic levels of recombination. DSBs were repaired in RTG in dmc1, but not rad51 mutants, hence repair did not occur by the usual meiotic mechanism which requires the Dmc1 gene product. In haploids, DSBs were also repaired quickly and efficiently upon RTG, showing that DSB repair did not require the presence of a homologous chromosome. In all strains examined, SC and related structures were not required for DSB repair or recombination following RTG.

Conclusions:

At least two pathways of DSB repair, which differ from the primary meiotic pathway(s), can occur during RTG: One involving interhomologue recombination, and another involving sister‐chromatid exchange. DSB formation precedes commitment to recombination. SC elements appear to prevent sister chromatid exchange in meiosis.
Two closely‐related left‐right asymmetrically expressed genes, lefty‐1 and lefty‐2: their distinct expression domains, chromosomal linkage and direct neuralizing activity in Xenopus embryos
Authors: Meno Chikara , Ito Yuzuru , Saijoh Yukio , Matsuda Youichi , Tashiro Kosuke , Kuhara Satoru , Hamada Hiroshi
Published: November 2003

Background:

Vertebrates have numerous lateral asymmetries in the position of their organs, but the molecular basis for the determination of left–right (L‐R) asymmetries remains largely unknown. TGFβ‐related genes such as lefty and nodal are L‐R asymmetrically expressed in developing mouse embryos, and may be involved in L‐R determination.

Results:

We have identified two highly conserved genes, lefty‐1 and lefty‐2, in the mouse genome. These two genes are tightly linked on mouse chromosome 1. lefty‐1 and lefty‐2 are both expressed in a L‐R asymmetric fashion in mouse embryos. However, the major expression domains of the two genes are different: lefty‐1 expression is predominantly confied to the left side of ventral neural tube, whereas lefty‐2 is strongly expressed in the lateral plate mesoderm on the left side. In embryos homozygous for the iv and inv mutation, which cause situs inversus, the expression sites of both genes are affected, either reversed or bilaterally, indicating that lefty‐1 and lefty‐2 are downstream of iv and inv. Although Lefty‐1 and Lefty‐2 prepro‐proteins are not readily processed in cultured cells, BMP2‐Lefty chimeric proteins can be processed to a secreted form. We have examined the activities of Lefty‐1 and Lefty‐2 in Xenopus embryos. In animal cap explants, Lefty‐1 and Lefty‐2 induce neural cells in the absence of mesoderm induction. The direct neuralizing activities of Lefty‐1 and Lefty‐2 thus seem remarkably similar to those of BMP antagonists such as noggin and chordin, suggesting that the action of Lefty‐1 and Lefty‐2 may be to locally antagonize BMP (bone morphogenic protein)‐mediated signals in tissues positioned on the left side of the mouse embryos.

Conclusion:

There are two lefty genes in mice (lefty‐1 and lefty‐2), both of which are expressed in a L‐R asymmetric fashion and are downstream of iv and inv. Lefty‐1 and Lefty‐2 possess direct neuralizing activity in Xenopus embryos, resembling the activities of BMP antagonists.
A novel form of the myeloid‐specific zinc finger protein (MZF‐2)
Authors: Murai Kasumi , Murakami Hiroshi , Nagata Shigekazu
Published: November 2003

Background:

Myeloid cell development is controlled by tissue‐specific transcription factors. Human myeloid zinc finger protein (MZF‐1) is a putative transcription factor containing 13 zinc fingers, and has been suggested that it regulates the development of neutrophilic granulocytes.

Results:

Here, we have isolated the murine and human cDNAs which encode a novel form of MZF protein (MZF‐2). Murine and human MZF‐2 proteins consisted of 814 and 775 amino acids, respectively, and have identity of 75.3% between them. The C‐terminal half of human MZF‐2, carrying the zinc finger domains, was completely identical with that of human MZF‐1, whereas the N‐terminal half of MZF‐2 was different from the corresponding region of human MZF‐1, and was coded by distinct exons. MZF‐2 mRNA was expressed in myeloid cells, particularly in the cells committed to the neutrophilic lineage, and down‐regulated by G‐CSF.

Conclusions:

MZF‐1 and MZF‐2 mRNAs seem to be produced by the alternative use of two different transcription initiation sites. The distinct N‐terminal half of MZF‐2 carries two characteristic domains, a leucine‐rich domain called LeR and an acidic domain, which suggests a unique function of MZF‐2 in neutrophil development.
Functional analyses of mammalian protein kinase C isozymes in budding yeast and mammalian fibroblasts
Authors: Nomoto Satoshi , Watanabe Yasuyuki , Ninomiya‐Tsuji Jun , Yang Li‐Xia , Kiuchi Kazutoshi , Hagiwara Masatoshi , Hidaka Hiroyoshi , Matsumoto Kunihiro , Irie Kenji
Published: November 2003

Background:

The PKC1 gene of Saccharomyces cerevisiae encodes a homologue of mammalian protein kinase C (PKC) that is required for yeast cell growth. Pkc1 has been proposed to regulate a protein kinase cascade which includes the Bck1, Mkk1/Mkk2 and Mpk1 kinases. The functional relationship between Pkc1 and mammalian PKCs is unknown. Another signal transduction in Saccharomyces cerevisiae, the mating pheromone signalling pathway, is mediated by a heterotrimeric G protein, and causes cell cycle arrest in the G1 interval. It is not clear whether PKC is involved in this pathway. The effects of overexpression of PKCs in mammalian cells have been widely studied to analyse the function of PKCs in vivo.

Results:

We isolated a human cDNA which encodes a protein kinase C type η (PKC‐η) by complementation of pkc1 mutations in Saccharomyces cerevisiae. The human PKC‐η was able to complement the growth defect caused by the deletion of PKC1, whereas PKC‐η was unable to suppress the defect caused by deletion of BCK1. We also isolated human cDNAs that can suppress the adaptation defect of sst2. One of them encodes a protein kinase C type δ (PKC‐δ). Expression of this gene in yeast stimulated an adaptation to the pheromone response. Human PKC‐δ suppressed the adaptation defect of a pheromone receptor mutation lacking its C‐terminal domain, but not that of a G protein β‐subunit mutation eliminating signal‐induced phosphorylation, and not the lethality of the gpa1 null mutation. Moreover, overexpression of PKC‐η in NIH3T3 cells induced anchorage‐independent growth.

Conclusions:

PKC‐η has a biological activity which is closely related to Pkc1, and PKC‐η activates the Pkc1‐mediated pathway through an activation of the Bck1 kinase that is a homologue of MAP kinase kinase kinase. PKC‐η appears to play a critical role in growth control of yeast and mammalian cells. Suppression experiments with PKC‐δ suggest that PKC‐δ desensitizes the pathway by regulating an aspect of G protein function.
A single copy of linker H1 genes is enough for proliferation of the DT40 chicken B cell line, and linker H1 variants participate in regulation of gene expression
Authors: Takami Yasunari , Nakayama Tatsuo
Published: November 2003

Background:

There is general agreement that large numbers of histone H1 are necessary for maintenance of the higher order structure of chromatin in higher eukaryotes. The chicken H1 gene family comprises six members per haploid genome, the total copy number being 12, and they encode six H1 variants which are considerably different from each other in amino acid sequence. We recently established that in two chicken DT40 mutants (1/2Δ110kb and Δ57kb), which lack, respectively, one allele of the gene cluster of 110 kb carrying six H1 genes, plus 33 core histone genes, and two copies each of four of the six H1 genes included in an ≈ 57 kb segment of the cluster, expression of the remaining H1 genes is increased, resulting in constant steady‐state levels of total H1 mRNAs. These results gave rise to the simple questions of how many H1 genes and how many H1 variants, at minimum, are necessary for the viability of DT40 cells.

Results:

We generated two DT40 mutants, Δ10/12H1 and Δ11/12H1, which are devoid, respectively, of two copies each of five H1 genes, and those plus a single copy of the last H1 gene, in addition to 17 core histone genes. Analyses involving a RNase protection assay, SDS‐PAGE and acid‐urea‐PAGE revealed, not only that in the Δ10/12H1 mutant the steady‐state levels of total H1 mRNAs and the amounts of histone H1 were not changed, but also that in the Δ11/12H1 mutant both were approximately one‐half the normal levels, and the amounts of HMG proteins were increased about twofold. No alteration in the growth rate or global chromatin structure was observed in either mutant. On the other hand, the protein patterns on 2D‐PAGE of the Δ11/12H1 mutant were definitely distinct from those of the wild‐type cell line.

Conclusion:

These results indicate not only that a lack of five of the six H1 variants causes changes in the protein patterns, but also that only a single copy of the H1 genes is enough for cell proliferation.
Conservative laparoscopic management of adnexal torsion in early pregnancy
Authors: Kuhn R. J. P. , Cullinan M.
Published: November 2003

We present the case of a patient with a right adnexal torsion in early pregnancy, which was treated laparoscopically.
Pelvic infection: a complication of laparoscopic ovarian drilling
Authors: Deans A. C , Wayne C , Toplis P. J
Published: November 2003

Laparoscopic ovarian drilling has been shown to be an effective treatment for anovulatory infertility secondary to polysystic ovary syndrome. We report a case where a tubo‐ovarian abscess developed following such a procedure and recommend that antibiotic prophylaxis and pre‐operative screening for infection become routine in this type of surgery.
Laparoscopic resection of pyosalpinx in early pregnancy
Authors: Jakiel G. , Wieczorek P. , Bakalczuk S. , Bokiniec M.
Published: November 2003

Laparoscopic surgery was performed on a patient with suspected intrauterine pregnancy. The patient's previous medical history and her strong wish for immediate surgery were also taken into account. An intrauterine pregnancy was found in the course of the operation. Following the resection of an inflamed tube, the operation was concluded without complications. Pregnancy‐maintaining drugs were administered. It was ascertained that the development of the embryo was physiologically correct and undisturbed, and that there were no uterine contractions. The patient remained under observation until the 22nd week of pregnancy. The case presented leads to the conclusion that cautious laparoscopic surgery on the reproductive organ in early pregnancy does not necessarily interfere with the further course of the pregnancy. In the literature through to 1996 accessible via MEDLINE, no more than 19 cases of operations on the reproductive organ during pregnancy are described. No inflammatory changes of the tubes are described in those reports, and no previous authors describe pregnancy loss as the result of laparoscopy.