Principal neuron spiking: neither necessary nor sufficient for cerebral blood flow in rat cerebellum

Neuronal activity, cerebral blood flow, and metabolic responses are all strongly coupled, although the mechanisms behind the coupling remain unclear. One of the key questions is whether or not increases in spiking activity in the stimulated neurons are sufficient to drive the activity-dependent rises in cerebral blood flow (CBF) that form the basis of the signals used in functional neuroimaging such as the blood oxygen level-dependent (BOLD) signal. To this end the present study examined the effect of enhanced spike activity per se on CBF in rat cerebellar cortex under conditions of disinhibition, achieved by blocking GABA_A receptors using either bicuculline or picrotoxin. Purkinje cell spiking activity and local field potentials were recorded by glass microelectrodes, and laser Doppler flowmetry was used to monitor CBF. Disinhibition increased Purkinje cell spiking rate to 200–300% of control without incurring any increase in basal CBF. This demonstrates that increased spike activity per se is not sufficient to affect basal CBF. The neurovascular coupling between excitatory synaptic activity and CBF responses evoked by inferior olive (climbing fibre) stimulation was preserved during disinhibition. Thus, the unchanged basal CBF in the presence of the dramatic rise in Purkinje cell spiking rate was not explained by impaired synaptic activity–CBF coupling. On the basis of our previous and the present studies, we conclude that increased spiking activity of principal neurons is neither sufficient nor necessary to elicit CBF responses and in turn BOLD signals, and that activation-dependent vascular signals reflect excitatory synaptic activity.     

Atypical maternal behavior,maternal representations,and infant disorganized attachment

The data for 197 mother-infant pairs from two longitudinal studies were analyzed to assess relations between maternal attachment representations; atypical maternal behavior, coded with a new tool. Atypical Maternal Behavior Instrument for Assessment and Classification (AMBIANCE), and infant attachment. Both maternal and infant attachment were systematically related to atypical maternal behavior: mothers who were Unresolved on the Adult Attachment Interview and those whose infants were disorganized in the Strange Situation Procedure engaged in more atypical behaviors than those who were not Unresolved and whose infants showed organized patterns of attachment, respectively. Regression analyses indicated that when tested as a mediator, atypical maternal behavior as measured on the AMBIANCE did not reduce the association between maternal Unresolved status and infant disorganized attachment. This may, in part, reflect the fact that our low-risk sample did not include enough cases in the risk categories. These data provide preliminary empirical validation for the AMBIANCE and strengthen the evidence for links between atypical maternal behavior and disorganized attachment but indicate that in addition to maternal attachment representations, other factors must contribute to atypical maternal behavior.     

An HLA study in 74 Danish haemochromatosis patients and in 21 of their families

HLA-A and -B alleles in 74 Danish patients and 21 homozygous relatives with idiopathic haemochromatosis (IH) were compared with those in a sample of 1719 chromosomes from healthy Danish control subjects. The following alleles occurred with higher frequencies in IH compared to controls: A3: 53.6% vs. 15.1% (Pc less than 0.001); B7: 33.1% vs. 15.6% (Pc less than 0.001); B14: 6.9% vs. 3.0% (Pc greater than 0.05); B38: 5% vs. 0.9% (Pc greater than 0.05); B47: 4.0% vs. 0.4% (Pc greater than 0.05). Pedigree analyses disclosed 19 different haplotypes in IH subjects, compared to 286 haplotypes in controls. The following haplotypes occurred with higher frequency in IH compared to controls: A3,B5: 10.3% vs. 0.3% (Pc less than 0.001); A3,B7: 25.6% vs. 6.6% (Pc = 0.001); A3,B14: 3.4% vs. 0.6% (Pc greater than 0.05); A3,B47: 6.9% vs. 0.2% (Pc greater than 0.05). The major IH marker HLA-A3 was found in 56% of the haplotypes. The patterns of HLA-alleles associated with IH in Denmark show similarities to those in Central Europe, Australia, USA and Canada, being A3,B7 dominated and those in Central Sweden, England and Ireland, being A3,B14 dominated.     

Role for mannose binding lectin in the prevention of Mycoplasma infection

Polymorphisms in exon 1 of the MBL-2 gene, resulting in reduced plasma levels of mannose binding lectin, were significantly overrepresented in 23 patients with primary antibody deficiency and culture-proven mycoplasma infections (P = 0.0038). This association persisted with the inclusion of a further nine suspected (doxycycline-responsive) cases (P = 0.0087). The lectin was shown to bind to three strains of mycoplasma.     

Increased gamma delta T cells in acute Plasmodium falciparum malaria

The T cell receptor of gamma delta is normally expressed on a small percentage of peripheral lymphocytes. Although the role of gamma delta T cells in the physiologic immune response is still unknown, there is accumulating evidence that gamma delta T cells may participate in the immune response to mycobacterial and other infectious organisms. In this study, we have quantitated the number of circulating gamma delta T cells during acute Plasmodium falciparum malaria. The results indicate that gamma delta T cells are elevated during the acute infection and remain elevated for at least 4 weeks during convalescence. T cells may participate in the immune response against P. falciparum by functioning as non-MHC restricted cytotoxic cells against intraerythrocytic parasites. Alternatively, lymphokines may be produced on antigen stimulation which may have antiparasitic activity.     

Heart rate recorder

We describe the design of an instrument that can acquire and store the average heart rate of a subject over 256 time intervals of predetermined length (1 or 6 min) during normal daily activities. The instrument consists of two units: a portable recorder, worn by the patient, detects and counts heart beats, and stores their average in memory, and a display later retrieves the contents of that memory. C.M.O.S. technology and programmable operational amplifiers resulted in low power consumption (20 mW). The results obtained from this instrument were accurate to about 1 beat/min compared with Holter monitoring and telemetry.     

Reassortment and interspecies transmission of North American H6N2 influenza viruses

To identify the protein encoded by a 687-bp open reading frame (ORF) of a salI genomic DNA fragment of shrimp white spot syndrome virus (WSSV), we expressed the ORF in a baculovirus/insect cell expression system. The apparent molecular mass of the recombinant protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was 35 kDa in insect cells. Antibody raised against bacterially synthesized protein of the ORF identified a nucleocapsid protein (VP35) in the extracts of both the purified WSSV virions and the nucleocapsids which comigrated with the 35-kDa baculovirus-expressed recombinant protein on SDS-PAGE. We also show by transient expression in insect cells (Sf9) that VP35 targets the nucleus. Two potential nuclear localization signals (NLSs) were characterized, but only one of them was important for targeting VP35 to the nuclei of transfected insect cells. Replacement of a cluster of four positively charged residues ((24)KRKR(27)) at the N terminus of the protein with AAAA resulted in mutant proteins that were distributed only in the cytoplasm, thus confirming that this sequence is a critical part of the functionally active NLS of VP35.