Intrahippocampal grafts of fetal basal forebrain tissue alter place fields in the hippocampus of rats with fimbria-fornix lesions

Intrahippocampal grafts of fetal basal forebrain tissue have been shown to restore several aspects of neural function, including some degree of behavioral recovery in spatial memory tasks, in rats with fimbria-fornix lesions. Place fields, the behavioral correlates of complex-spike unit activity recorded in the hippocampus of rats, are altered by fimbria-fornix lesions, and provide an important measure of the functioning circuitry of the hippocampus after grafts. To investigate the effects of grafts on hippocampal circuitry, complex-spike units were recorded while the rats traversed a radial maze. Quantitative analyses of spatial activity showed that units in normal rats had spatially clustered, reliable place fields that were stable despite alterations of the maze. In contrast, units in rats with fimbria-fornix lesions had more dispersed, less reliable place fields that were disrupted when the maze was covered or rotated. Compared to rats with fimbria-fornix lesions, rats with grafts and units with more tightly clustered, more reliable, and more stable place fields when the maze was altered. The results suggest that: (1) fimbria-fornix lesions disrupt some aspects of complex-spike place field activity; (2) the functioning of hippocampal circuitry is influenced by fetal basal forebrain grafts; and (3) the grafts may ameliorate the effects of lesions on spatial behaviors by influencing critical aspects of place field activity in the hippocampus.     

Use of antisera to the isolated alpha and beta subunits of C3 as probes to study functional sites present on particle-bound C3b but absent on native soluble forms of C3

The effect of antisera to the isolated alpha and beta chains of C3 on certain C3b-dependent reactions has been studied. C5-mediated haemolysis of EAC1423b was inhibited preferentially by antiserum to the alpha chain, whereas antiserum to the beta chain inhibited the formation of C3bBb. The anti-beta chain antiserum also stabilised C3bBbP, and rendered the enzyme relatively resistant to accelerated decay in the presence of factor H. These and previous findings that anti-alpha and anti-beta IgG bind to restricted subsets of antigenic determinants on C3/C3b suggest that these antisera affect C3b function through the binding of antibodies to active binding sites exclusively exposed by bound C3b. The anti-alpha and anti-beta antibody probes are currently being further developed to verify this interpretation.     

POLYMORPHISM OF BOVINE MHC CLASS II GENES. JOINT REPORT OF THE FIFTH INTERNATIONAL BOVINE LYMPHOCYTE ANTIGEN (BOLA) WORKSHOP,INTERLAKEN, SWITZERLAND, 1 AUGUST 1992

Polymorphism of the bovine DRB, DQA, DQB, DYA, DOB and DIB genes was investigated using restriction fragment length polymorphism (RFLP) analysis, isoelectric focusing (IEF), class II serology and polymerase chain reaction (PCR) based typing techniques. The simultaneous application of multiple typing techniques and the characterization of multiple genes resulted in a greatly enhanced picture of the bovine class II regions. Thirty-eight class IIa (DR-DQ) and 5 class lib (DYA-DOB-DIB) haplotypes were defined. It was found that IEF types were associated with DRB3 polymorphism defined by DRB3 PCR-RFLP and DRB3 microsatellite PCR. Serologically defined polymorphism was associated with distinct molecular/IEF motifs and, therefore, DR and DQ specificities could be tentatively distinguished. Although the DR and DQ genes are tightly linked, neither DR nor DQ typing defined all of the class IIa region polymorphism. Furthermore, even the most powerful DRB3 typing technique, DRB3 PCR-RFLP, failed to detect all expressed DRB3 polymorphism. All detected DRB3 polymorphism could, however, be distinguished with a combination of two molecular techniques: DRB3 PCR-RFLP and DRB3 microsatellite PCR. RFLP typing with transmembrane probes detected significantly less polymorphism than typing with cDNA or exon probes. However, the transmembrane probes were useful because they were locus specific. The presence of only 5 of 12 possible class lib haplotypes was unexpected and indicates that the DYA, DOB and DIB genes are tightly linked.     

Evidence for the involvement of blood flow-related mechanisms in the ovulatory process of the rat

To elucidate whether any relationship exists between ovarian blood flow and ovulation rate, the effects on these parameters were examined in equine chorionic gonadotrophin/human chorionic gonadotrophin (eCG/HCG) (15I U/15I U) primed rats after bilateral ligation and severance of either the ovarian branch of the uterine artery and vein (UL), the ovarian artery and vein (OL) or both sites (UL+OL) in comparison to sham operations. Laser Doppler flowmetry demonstrated the presence of microcirculatory vasomotion and a reduction of blood flow after UL, OL and UL+OL performed during the intervals 0-3 h (78, 66 and 19% of pretreatment values respectively) and 6-9 h (68, 57 and 20%) after HCG. Experiments utilizing radioactive microspheres also indicated decreased ovarian blood flow by UL and OL. Ovulation rate was assessed 20 h after HCG in animals where ligations had been performed at 0, 3, 6 and 9 h after HCG. No ovulations were seen after UL+OL and significantly decreased ovulation rates ( approximately 50% of sham operated animals) were seen after UL at 0 and 3 h and after OL at 0, 6 and 9 h. Progesterone concentrations in blood 20 h after HCG were reduced by OL but not UL and ovarian weights were unaffected by ligation. It is concluded that acute blood flow reduction during the ovulatory interval reduces ovulation rate in the rat.     

Human mast cell migration in response to members of the transforming growth factor-beta family

Mast cells are known to accumulate at sites of inflammation, however, the chemotaxins involved remain largely undefined. Transforming growth factor-beta (TGF-beta) isoforms regulate numerous cellular functions, including cell growth and differentiation, formation of extracellular matrix, and the immune response. In this study we have compared the potency of different members of the TGF-beta family as human mast cell chemotaxins, and analyzed the expression of TGF-beta binding proteins on human mast cells. We were able to demonstrate that the maximal chemotactic response was attained at approximately 40 fM for the three TGF-beta isoforms, with TGF-beta3 being more effective than TGF-beta1 and TGF-beta2 at this concentration. This effect was observed in both the HMC-1 human mast cell line and in cultured primary mast cells. In addition, TGF-beta1, TGF-beta2, and less efficiently, TGF-beta3 inhibited the proliferation of HMC-1 cells. The migratory response is probably mediated through interaction with the TGF-beta serine/threonine type I and II receptors that were found to be expressed on the cells. No expression of TGF-beta type III receptor, endoglin, or the endothelial TGF-beta type I receptor ALK-1 could be detected. These results provide evidence that TGF-beta isoforms are highly potent chemotaxins for human mast cells and can play an important role in the recruitment of mast cells in inflammatory reactions.     

PMM2 mutation spectrum, including 10 novel mutations, in a large CDG type 1A family material with a focus on Scandinavian families

Carbohydrate-deficient glycoprotein syndrome type IA (CDG IA) is an autosomal recessive disease characterized clinically by severe involvement of the central and peripheral nervous system, and biochemically by complex defects in carbohydrate residues in a number of serum glycoproteins. CDG IA is caused by mutations in the PMM2 gene located in chromosome region 16p13. In this study, 61 CDG type IA patients (122 chromosomes) were screened for mutations in the PMM2 gene using a combination of SSCP and sequence analysis. More than 95% of the mutations could be detected. All of them were missense mutations. Mutations 422G>A and 357C>A were strikingly more common in the material and comprised 58% of mutations detected. Of the 20 mutations found, 10 were not reported previously. Seven mutations, e.g. 26G>A (five alleles) and 548T>C (seven alleles), were found only in Scandinavian families. The most common genotype was 357C>A/422G>A (36%). Three patients were homozygous, 357C>A/357C>A (two cases), and 548T>C/548T>C (one case). No patients homozygous for the most common mutation 422G>A were detected. The different mutations were clustered e.g., in that most were located in exon 5 (five) and exon 8 (six), while no mutation was detected in exon 2. When the frequencies of each mutation were included, exon 5 comprised 61% (65 chromosomes) of the mutations; in Scandinavian patients the frequency of these mutations was 72%. Thus, analysis of exon five in these patients enables both reliable and time-saving first screening in prenatal diagnostic cases. This could be followed by a second step of additional strategies for the detection of other mutations.     

Release of histamine in whole blood by oxygen radicals: Division between specific and unspecific processes

Oxygen derived free radicals are involved in many pathological processes such as postischemic reperfusion injuries, hepatotoxicity of drugs and inflammatory processes. Thereby these oxygen radicals induce lipid peroxidation and perturbation of cellular membranes. The aim of our present study was to determine whether oxygen radicals generated by the xanthine oxidase/hypoxanthine system cause a release of histamine in human blood cell cultures. Stimulation of blood cell cultures with oxygen radicals induced a histamine liberation which was mainly due to calcium independent processes during the first 30 min, whereas then calcium requiring processes took part in the release of histamine. The regulation of the leukocyte selectin LECAM-1 was altered by oxygen radicals whereas histamine, which is known to modulate vascular selectin expression, did not affect the expression of LECAM-1. Our data indicate that oxygen radicals induce a direct calcium independent release of histamine which is due to membrane pertubating processes during the first phase but also induce a specific reaction leading to a further indirect histamine liberation which is probably mediated by PAF.accepted by W. LorenzThe first two authors contributed equally to this paper.     

The alpha rhythm in the electroencephalogram: A theory based on a neurophysiological model

A column in the cerebral cortex is made up of a group of neurons and is considered to be a functional unit. Previous work has suggested that a column has two separate levels of activity, and that only a few of the columns are at the high level of activity simultaneously. To keep this number within proper limits, it is necessary to have a regulating system that reduces the cortical excitability when the number tends to increase, and vice versa. In the present paper, it is proposed that these changes up and down in the excitability can explain the generation of the alpha rhythm in the electroencephalogram. Preliminary results show that a normal alpha rhythm of about 10 Hz can be generated when the number of columns with high activity is shifting between four and five. The duration of the high activity of a column is around 450 ms.     

A novel two colour ELISPOT assay. I. Simultaneous detection of distinct types of antibody-secreting cells

A novel assay system has been developed which is based on the ELISPOT methodology and employs a combination of two immunoenzyme visualization systems yielding distinct colour products. This variation permits the simultaneous enumeration of two different types of cell secreting antigenically distinct products. Optimal conditions for the concurrent detection of human mononuclear cells secreting IgG or IgA antibodies are described.