Certain peptides with sequences related to part of the major histocompatibility complex class I antigen enhance the action of insulin. These peptides also aggregate into fibrous structures that seem to be related to their biological activity. In the current study, the 17-residue peptide with amino acid sequence Gly-Asn-Glu-Gln-Ser-Phe-Arg-Val-Asp-Leu-Arg-Thr-Leu-Leu-Arg-Tyr-Ala is used as a representative example of these bioactive molecules. As seen by electron microscopy, the peptide associates into gently twisted ribbons, 50 A thick, in which the amount of twist decreases as the ribbons become wider. X-ray diffraction analysis suggests that the peptides are arranged as in an antiparallel beta-sheet extending essentially endlessly along the fiber axis. The amino acid sequence of the peptide is such that one side of the beta-sheet is predominantly polar while the opposite side is nonpolar. This allows the beta-sheets to form multilayers with alternating hydrophobic and hydrophilic interfaces. The length of the extended peptide (approximately 54 A) determines the thickness of the ribbon and the tendency of individual beta-sheets to twist accounts for the twisting of the ribbons. An alternative model is also discussed, again based on antiparallel beta-sheets, but with adjacent sheets interdigitated in a "side-by-side" fashion rather than forming stacked layers. Comparable inactive peptides such as Gly-Asn-Glu-Gln-Ser-Ala-Arg-Val-Asp-Leu-Arg-Thr-Leu-Leu-Arg-Tyr-Tyr (changed amino acids underlined) do not form ordered filamentous structures.

Amino Acid Sequence↗

PubMedDate not supplied

Behavioural effects of prenatal metallic mercury inhalation exposure in rats.

The effects of administration by inhalation of metallic mercury vapour (Hg0) to pregnant rats, approximately corresponding to doses of 0.2 mg Hg0/kg/day (high dose) or 0.07 mg Hg0/kg/day (low dose), on the developmental and behavioural repertoire of the offspring were studied. Exposure occurred during days 11-14 plus 17-20 of gestation. The dose levels were selected so as not to induce maternal toxicity. Maturation variables such as surface righting, negative geotaxis, pinna unfolding, and tooth eruption revealed no differences between Hg0-treated offspring and controls. Tests of spontaneous motor activity showed that the Hg0-treated offspring were hypoactive at 3 months of age but hyperactive at 14 months. In spatial learning tasks the prenatally exposed offspring showed retarded acquisition in the radial arm maze but no differences in circular swim maze. A simple test of learning, habituation to a novel environment (activity chambers), indicated a reduced ability to adapt. These data suggest that prenatal exposure to Hg0 vapour results in similar behaviour changes in the offspring as reported for methylmercury.

Administration, Inhalation↗

PubMedDate not supplied

Possible roles of compound membrane receptors in the immune system.

A compound receptor is defined as a molecular complex which attains its final, biologically active structure by rearrangement and assembly in the membrane of several structural subunits. The existence of such receptor complexes is strongly suggested by experiments which demonstrated a very close association between certain ligand (primarily insulin) receptors and the major histocompatibility complex (MHC) antigens. We present here speculations on the possible role of MHC as a structural part of a multitude of receptors with different biological functions, and we argue that recent immunological data on minor histocompatibility antigens, antigen-presenting cells and T-lymphocyte receptors fit into this hypothesis.

Animals↗

PubMedDate not supplied

Cost analysis of ethanol production from willow using recombinant Escherichia coli.

This study comprises a technical and economic analysis of the production of fuel ethanol by fermentation of a pentose-rich hydrolysate with recombinant Escherichia coli, strain KO11. Hydrolysate from steam-pretreated willow was used as raw material in calculations regarding the fermentation. The calculations were based on a feed capacity of 10 metric tons of dry willow per hour to the pretreatment stage, providing 35 metric tons of hydrolysate per hour, consisting of 45 g of sugars/L, to the pentose fermentation plant. A detoxification step was included, since the hydrolysate has been shown to have an inhibitory effect on the E. coli KO11. The technical data used in the calculations were based on a kinetic fermentation model, which was developed from laboratory-scale experiments in a previous study. The economic analysis predicted an ethanol production cost of 48/L in the pentose fermentation plant, indicating potentially good economy. The detoxification cost constitutes 22% of this cost. Sensitivity analyses revealed that if the concentration of sugars in the feed to the fermentation was decreased by 40% to 27 g/L, the ethanol production cost was increased to 54/L. The production cost was increased to 50/L ethanol if the cell mass was recirculated to the fermentation stage 5 times instead of 20.

Biotechnology↗

PubMedDate not supplied

Cranial neural crest cell migration in the Australian lungfish, Neoceratodus forsteri.

A crucial role for the cranial neural crest in head development has been established for both actinopterygian fishes and tetrapods. It has been claimed, however, that the neural crest is unimportant for head development in the Australian lungfish (Neoceratodus forsteri), a member of the group (Dipnoi) which is commonly considered to be the living sister group of the tetrapods. In the present study, we used scanning electron microscopy to study cranial neural crest development in the Australian lungfish. Our results, contrary to those of Kemp, show that cranial neural crest cells do emerge and migrate in the Australian lungfish in the same way as in other vertebrates, forming mandibular, hyoid, and branchial streams. The major difference is in the timing of the onset of cranial neural crest migration. It is delayed in the Australian lungfish in comparison with their living sister group the Lissamphibia. Furthermore, the delay in timing between the emergence of the hyoid and branchial crest streams is very long, indicating a steeper anterior-posterior gradient than in amphibians. We are now extending our work on lungfish head development to include experimental studies (ablation of selected streams of neural crest cells) and fate mapping (using fluoresent tracer dyes such as Dil) to document the normal fate as well as the role in head patterning of the cranial neural crest in the Australian lungfish.

Animals↗

PubMedDate not supplied

Occurrence of delirium in different regional brain syndromes.

Old age and organic brain disorder are major risk factors for delirium in the elderly. The localization of the brain damage in dementia may be of importance for this risk. The aim of the present study was to investigate the rate of delirium in patients with different regional brain syndromes. Included in the study were 194 demented patients. The occurrence and intensity of four regional brain syndromes were estimated: parietal lobe syndrome, frontal lobe syndrome, subcortical syndrome and global brain syndrome. The analyses showed that the rate of delirium was significantly higher when a global brain syndrome was predominant than when any one of the other syndromes predominated.

Aged↗

PubMedDate not supplied

Effect of the immune modulators BM 12.531 (azimexone) and BM 41.332 on the subsets of T-lymphocytes in mice.

The immunomodulating 2-cyanaziridine derivatives BM 12.531 (azimexone) and BM 41.332 have no effects on the total amount of T-lymphocytes in the spleen of mice but increase dose-dependently the percentage of Ly1-, 2+, 3+ T-lymphocytes (killer/suppressor) and decrease the percentage of Ly1+, 2-, (helper) cells. These investigations were carried out by means of specific monoclonal antibodies and fluorescence-activated cell sorting. The increase in Ly2+-cells is mainly due to increased suppressor activity.

Adjuvants, Immunologic↗

PubMedDate not supplied

[The elderly and social change--an interdisciplinary study on Sweden in the 19th and 20th centuries].

This research report presents an overview of historical studies within the context of the interdisciplinary Swedish project on aging. The author discusses the project's conceptual framework and focuses on conflict theory and exchange theory as major models. The empirical studies concern changes in the provisions for old age and in the aging processes of the major social groups (farmers, rural proletarians, urban artisans and their wives, male and female industrial workers). The project aims at integrating a life course perspective in the analysis of social change. Class and gender are underlined as major forces in shaping the status of the aged in the last two centuries.

Aged↗

PubMedDate not supplied

Adjustable computerized stereotaxic brain atlas for transmission and emission tomography.

A computerized brain atlas adjustable to the patient's anatomy would serve serveral purposes. It could be used in stereotaxic surgery. Even more important would be its use in medical imaging to identify various brain structures, such as the basal ganglia and their nuclei, as well as individual cortical gyri. This atlas could be used for additional mapping of nonvisible structures in images obtained with methods having a high spatial resolution, such as computed tomography and nuclear magnetic resonance. Anatomic information obtained in this way might then be transferred to images of low resolution, such as those obtained in positron emission tomography or single-photon emission computed tomography, in order to select anatomically correct regions of interest. The methods used in the construction of such an atlas are briefly described. An attempt to implement such an atlas based on digitized photographs of brain slices is described.

Brain↗