DIET OF HARBOR PORPOISES IN THE KATTEGAT AND SKAGERRAK SEAS: ACCOUNTING FOR INDIVIDUAL VARIATION AND SAMPLE SIZE

Stomach contents of 112 bycaught harbor porpoises ( Phocoena phocoena ) collected between 1989 and 1996 in the Kattegat and Skagerrak seas were analyzed to describe diet composition and estimate prey size, to examine sample size requirements, and to compare juvenile and adult diets. Although porpoises preyed on a variety of species, only a few contributed substantially to the diet. Atlantic herring ( Clupea harengus ) was the dominating prey species for both juveniles and adults. Our results, in combination with those from previous studies, suggest that where herring is a dominant food source, porpoises prey primarily on size classes containing mature or maturing individuals. Further, we also show that Atlantic hagfish ( Myxine glutinosa ) may be an important food resource, at least for adult porpoises. Examination of sample size requirement showed that, depending on the taxonomic level used to describe the diet, a minimum of 35–71 stomachs are needed to be confident that all common prey species will be found.     

The braincase and palate of the tetrapodomorph sarcopterygian mandageria fairfaxi: morphological variability near the fish–tetrapod transition

The braincase of the Late Devonian tristichopterid sarcopterygian Mandageria fairfaxi , from Canowindra, NSW, Australia, differs radically from the conservative pattern present in other 'osteolepiforms' (stem–group tetrapodomorph fishes) and non–dipnoan sarcopterygian fishes in general. The basioccipital region is short, displaced anteriorly, and either unossified or loosely articulated to the exoccipital, leaving most or all of the notochordal tunnel open ventrally. The exoccipital complex, which is developed into a large saddle that would have rested on top of the notochord, carries large, triangular articular facets on its posterior face and appears to have formed part of a functional neck joint, a synovial articulation between the skull and vertebral column that allows the former to rotate against the latter. Such a joint is characteristic of post–Devonian tetrapods, but unknown in other sarcopterygians. We infer that the ventrally open notochordal tunnel allowed gentle flexion of the cranial notochord during (predominantly vertical) rotational movement at the occiput; this is a mechanically unique solution to the problem of creating a mobile neck. Other unusual features of Mandageria include a posteriorly located lateral commissure, and structures on the entopterygoid and lateral commissure that may have been associated with an elaborate spiracular tract.     

Inhibition of Cortisol Secretion by Dexamethasone in Relation to Body Fat Distribution: A Dose-Response Study

In this study, dexamethasone (dex) was administered in random order in doses of 0.05, 0.125, 0.25 and 0.5 mg at 10 p.m. with measurements of serum Cortisol in the morning (8 a.m.) of this and the following day. The test was performed on 22 apparently healthy men, 40 to 60 years of age, recruited from laboratory personnel, outpatient clinics or advertisements in a newspaper. Eight had a body mass index (BMI) (kg/m²) of <25 and 14 of >25. Twelve men had a waist hip ratio (WHR) of <1.0 and 10 men had a WHR of<1.0. Cortisol values at baseline were correlated inversely with WHR and were usually lower in men with a high (>1.0) rather than a low than low (<1.0) WHR after dex inhibition. There was apparently no inhibition by dex at 0.05 and 0.125 mg on average in men with a WHR of >1.0. In addition, the inhibition at 0.5 mg dex correlated negatively with the WHR and was significantly lower (p<0.05) in men with a WHR of >1.0 than in men with a WHR of <1.0. None of these differences or relationships was found to be dependent on BMI. It is concluded that men with an elevated WHR experience a decrease in the inhibition of Cortisol secretion by dex. It is suggested that this could explain or contribute to the elevated sensitivity of their HPA axis. Furthermore, lower morning Cortisol concentrations suggest a change in diurnal secretion patterns.     

Growth Hormone Treatment of Hypophysectomized Rats Increases Catecholamine-induced Lipolysis and the Number of β-Adrenergic Receptors in Adipocytes: No Differences in the Effects of Growth Hormone on Different Fat Depots

Growth hormone (GH) has a lipolytic effect in adipose tissue but this effect may differ in adipose tissue from various fat depots. This latter possibility was investigated in the present study, in which the effects of GH in vivo on catecholamine-induced lipolysis and the number of β-adrenergic receptors in isolated adipocytes from different fat depots of hypophysectomized rats were investigated. Female and male Sprague-Dawley rats were hypophysectomized or sham-operated at 45 days of age. One week after the operation, hormonal replacement therapy with L-thyroxine and hydrocortisone acetate was given. In addition, groups of rats were treated with GH (1.33 mg/kg per day, given as two daily subcutaneous injections). After 1 week of hormonal treatment, adipocytes were isolated from the parametrial, epididymal and inguinal fat pads, and glycerol release after catecholamine-stimulation and ¹²⁵I-cyanopindolol binding were measured. Hypophysectomy resulted in a marked decrease in the lipolytic response to catecholamines. GH treatment significantly increased catecholamine-induced lipolysis with similar effects in adipocytes from parametrial or epididymal and inguinal fat depots in both female and male rats. There were no differences between norepinephrine compared with isoproterenol-induced responses. ¹²⁵I-cyanopindolol binding was reduced after hypophysectomy and normalized by GH treatment, without differences between parametrial and inguinal adipose tissue regions. We conclude that the lipolytic effects of GH in the rat may partly be mediated by a stimulatory effect on β-adrenergic receptors in adipocytes. In addition, GH exerted similar effect on catecholamine-induced lipolysis and β-adrenergic receptors in adipocytes from parametrial, epididymal and inguinal fat depots.     

Psednotrichia, a genus of the tribe Senecioneae hitherto misplaced in the Astereae (Asteraceae)

Anderberg, A. A. & Karis, P. O. 1995. Psednotrichia , a genus of the tribe Senecioneae hitherto misplaced in the Astereae (Asteraceae). — Nord. J. Bot. 15: 375–379. Copenhagen. ISSN 0107–055X.
The tribal position for the little known genus Psednorrichia , is established. This monotypic genus, hitherto placed in the tribe Astereae, is a congener of Xyridopsis of the tribe Senecioneae (Asteraceae). The two species of Xyridopsis are here transferred to Psednotrichia and the new combinations P. xyridopsis and P. newtonii are made. A brief discussion of the morphology of the genus, and its systematic position within the tribe Senecioneae is provided.     

Disruption of the Cytokeratin Cytoskeleton and Inhibition of Hepatocytic Autophagy by Okadaic Acid

To learn whether autophagy might be dependent on any of the major cytoskeletal elements, the effect of various cytoskeleton inhibitors on autophagy and cytoskeletal organization was studied in isolated rat hepatocytes. Autophagy, measured as the sequestration of endogenous lactate dehydrogenase, was completely inhibited in isolated rat hepatocytes by the protein phosphatase inhibitor okadaic acid (30 nM). Only small effects were seen with vinblastine (10 μM) or cytochalasin D (10 μM). Indirect immunofluorescence microscopy with antibody to a 55-kDa cytokeratin, corresponding to human cytokeratin 8 (CK8), revealed that whereas control cells contained a well-organized network of cytokeratin intermediate filaments, okadaic acid disrupted this network into small spherical aggregates. Treatment with cytochalasin D or vinblastine, which disrupt microfilaments and microtubules, respectively, had no detectable effect on the cytokeratin filament distribution. Neither the microtubule network (detected by indirect immunofluorescence with antibodies against α- and β-tubulin) nor the actin microfilament network (detected by rhodamine-palloidin) was disrupted by okadaic acid. Naringin (100 μM), a putative protein kinase-inhibitory flavonoid, offered complete protection against the autophagy-inhibitory and cytokeratin-disruptive effects of okadaic acid. Two other flavonoids, genistein (100 μM) and prunin (100 μM) as well as KN-62 (10 μM), a specific inhibitor of Ca²⁺/calmodulin-dependent kinase II), likewise displayed a good ability to protect against the effect of okadaic acid upon cytokeratin organization, while no such protection was seen with H-89 (20 μM), an inhibitor of the cyclic nucleotide-dependent protein kinases, or with H-7 (100 μM), which in addition inhibits protein kinase C. The results suggest that the cytokeratin cytoskeleton of hepatocytes is subject to rapid control by phosphorylation and dephosphorylation and that cytokeratin filaments may somehow be involved in the autophagic process.     

Physical Activity,Obesity, and Cardiovascular Risk Factors in Children. The Belgian Luxembourg Child Study II

GUILLAUME, MICHÈLE, LEIF LAPIDUS, PER BJÖRNTORP, ANDRE LAMBERT. Physical activity, obesity, and cardiovascular risk factors in children. The Belgian Luxembourg Child Study II. Physical activity was measured in relation to cardiovascular (CV) risk factors in a randomly selected population of 1028 children from Province de Luxembourg in Belgium, a mainly rural area with a high prevalence of such risk factors among adults and children. Physical activity was estimated as participation in sport activities, a major indicator of leisure-time physical activity in schoolchildren, and physical inactivity was estimated as frequency and duration of television (TV) watching. Boys participated more frequently in sport activities than girls did (p=0. 001). A majority of the children watched TV daily. After age adjustment, bodyweight (girls, p<0. 012; boys, p<0. 027) and, in boys, body mass index (BMI) (p<0. 039) were related to days per week of TV watching. No significant relationships with other CV risk factors remained after adjustments for BMI. In analyses of independent contributions of age, TV watching, and sports activity on CV risk factors, age showed highly significant relationships. In boys, TV showed relationships with BMI (P<0. 04) and (borderline) with systolic blood pressure, independent of age and sports activity, whereas the latter was significantly related to subscapular skinfold (p<0. 04) and (borderline) with triceps skinfold and cholesterol. In girls, no significant independent contributions to risk factor associations were found. The father's education was directly associated with sports activities, whereas the mother being a housewife showed negative relationships to physical activity and positive to TV watching in their children, suggesting socioeconomic influence on the activity patterns of children. Furthermore, registrations suggested less physical activity in the most rural part of the area. It is concluded that children in this mainly rural area watch TV frequently. In boys, physical inactivity, measured both as TV watching and as registrations of sports activities, contributes independently to body fat mass. In girls, no contribution or weaker contributions of physical inactivity were found. This suggests that contributory factors leading to obesity might be different in girls and boys.     

Immunotherapy of human colon cancer by antibody-targeted superantigens

T lymphocytes generally fail to recognize human colon carcinomas, suggesting that the tumour is beyond reach of immunotherapy. Bacterial superantigens are the most potent known activators of human T lymphocytes and induce T cell cytotoxicity and cytokine production. In order to develop a T-cell-based therapy for colon cancer, the superantigen staphylococcal enterotoxin A (SEA) was given tumour reactivity by genetic fusion with a Fab fragment of the monoclonal antibody C242 reacting with human colon carcinomas. The C242Fab-SEA fusion protein targeted SEA-reactive T cells against MHC-class-II-negative human colon carcinoma cells in vitro at nanomolar concentrations. Treatment of disseminated human colon carcinomas growing in humanized SCID mice resulted in marked inhibition of tumour growth and the apparent cure of the animals. Therapeutic efficiency was dependent on the tumour specificity of the fusion protein and human T cells. Immunohistochemistry demonstrated massive infiltration of human T cells in C242Fab-SEA-treated tumours. The results merit further evaluation of C242Fab-SEA fusion proteins as immunotherapy in patients suffering from colon carcinoma.     

Three-dimensional structure prediction of the NAD binding site of proton-pumping transhydrogenase from Escherichia coli

A three-dimensional structure of the NAD site of Escerichia coli transhydrogenase has been predicted. The model is based on analysis of conserved residues among the transhydrogenases from five different sources, homologies with enzymes using NAD as cofactors or substrates, hydrophilicity profiles, and secondary structure predictions. The present model supports the hypothesis that there is one binding site, located relatively close to the N-terminus of the α-subunit. The proposed structure spans residues α145 to α287, and it includes five β-strands and five α-helices oriented in a typical open twisted α/β conformation. The amino acid sequence following the GXGXXG dinucleotide binding consensus sequence (residues α172 to α177) correlates exactly to a typical fingerprint region for ADP binding βαβ folds in dinucleotide binding enzymes. In the model, aspartic acid α195 forms hydrogen bonds to one or both hydroxyl groups on the adenosine ribose sugar moiety. Threonine α196 and alanine α256, located at the end of βB and βD, respectively, create a hydrophobic sandwich with the adenine part of NAD buried inside. The nicotinamide part is located in a hydrophobic cleft between αA and βE. Mutagenesis work has been carried out in order to test the predicted model and to determine whether residues within this domain are important for proton pumping directly. All data support the predicted structure, and no residue crucial for proton pumping Was detected. Since no three-dimensional structure of transhydrogenase has been solved, a well based tertiary structure prediction is of great value for further experimental design in trying to elucidate the mechanism of the energy-linked proton pump. © 1995 Wiley-Liss, Inc.