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We have previously shown that there are clear differences between spontaneous excitatory synaptic currents recorded in layers V and II of the rat entorhinal cortex (EC) in vitro, and have suggested that these might contribute to a more pronounced susceptibility of the deeper layer to epileptogenesis. In the present study, we have made a detailed comparison of spontaneous synaptic inhibition between the two layers by recording spontaneous inhibitory synaptic currents (sIPSCs) using whole-cell patch-clamp techniques in EC slices. Pharmacological studies indicated that sIPSCs were mediated exclusively by gamma-aminobutyric acid (GABA)(A) receptors. There was little difference in average amplitudes, rise or decay times of sIPSCs in layer II compared with layer V. However, in the former, events occurred at 4-5 times the frequency seen in the latter, and frequencies of

Sound features are blended together en route to the central nervous system before being discriminated for further processing by the cortical synaptic network. The mechanisms underlying this synaptic processing, however, are largely unexplored. Intracortical processing of the auditory signal was investigated by simultaneously recording from pairs of connected principal neurons in layer II/III in slices from A1 auditory cortex. Physiological patterns of stimulation in the presynaptic cell revealed two populations of postsynaptic events that differed in mean amplitude, failure rate, kinetics and short-term plasticity. In contrast, transmission between layer II/III pyramidal neurons in barrel cortex were uniformly of large amplitude and high success (release) probability (Pr). These unique features of auditory cortical transmission may provide two distinct mechanisms for discerning and separating transient from stationary features of the auditory signal at an early stage of cortical processing.

We have previously shown that presynaptic N-methyl-D-aspartate receptors (NMDARs) can facilitate glutamate release onto principal neurons in the entorhinal cortex (EC). In the present study, we have investigated the subunit composition of these presynaptic NMDARs. We recorded miniature alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated excitatory postsynaptic currents (mEPSCs), from visually identified neurons in layers II and V of the EC in vitro. In both layers, bath application of the NR2A/B subunit-selective agonist, homoquinolinic acid (HQA), resulted in a marked facilitation of mEPSC frequency. Blockade of presynaptic Ca(2+) entry through either NMDARs or voltage-gated Ca(2+) channels with Co(2+) prevented the effects of HQA, confirming that Ca(2+) entry to the terminal was required for facilitation. When the NR2B-selective antagonist, ifenprodil, was applied prior to HQA, the increase in mEPSC frequency was greatly reduced. In addition, we found that an NMDAR antagonist blocked frequency-dependent facilitation of evoked release and reduced mEPSC frequency in layer V. Thus we have demonstrated that NMDA autoreceptors in layer V of the EC bear the NR2B subunit, and that NMDARs are also present at terminals onto superficial neurons.

In a previous study we showed that activation of a presynaptically located metabotropic glutamate receptor (mGluR) with pharmacological properties of mGluR4a causes a facilitation of glutamate release in layer V of the rat entorhinal cortex (EC) in vitro. In the present study we have begun to investigate the intracellular coupling linking the receptor to transmitter release. We recorded spontaneous alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated excitatory postsynaptic currents (EPSCs) in the whole cell configuration of the patch-clamp technique, from visually identified neurons in layer V. Bath application of the protein kinase A (PKA) activator, forskolin, resulted in a marked facilitation of EPSC frequency, similar to that seen with the mGluR4a specific agonist, ACPT-1. Preincubation of slices with the PKA inhibitor H-89 abolished the effect of ACPT-1, as did preincubation with the adenylate cyclase inhibitor, SQ22536. Activation of protein kinase C (PKC) using phorbol 12 myristate 13-acetate (PMA) did not affect sEPSC frequency; however, it did abolish the facilitatory effect of ACPT-1 on glutamate release. A robust enhancement of EPSC frequency was seen in response to bath application of the specific PKC inhibitor, GF 109203X. Both H-89 and the group III mGluR antagonist (RS)-alpha-cyclopropyl-4-phosphonophenylglycine (CPPG) abolished the effects of GF 109203X. These data suggest that in layer V of the EC, presynaptic group III mGluRs facilitate release via a positive coupling to adenylate cyclase and subsequent activation of PKA. We have also demonstrated that the PKC system tonically depresses transmitter release onto layer V cells of the EC and that an interaction between mGluR4a, PKA, and PKC may exist at these synapses.

Whole cell voltage clamp recording was used to investigate neurotransmitter release onto neurones in deep and superficial layers of rat entorhinal cortex in vitro. Activation of metabotropic glutamate receptors with the agonist (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid depressed spontaneous release of the inhibitory neurotransmitter GABA in layer V, but not in layer II. Depression of transmitter release did not persist in the presence of the sodium channel blocker tetrodotoxin. It seems likely that activation of presynaptic glutamate heteroreceptors inhibits action potential dependent release of neurotransmitter via a direct action at the presynaptic terminal. We confirmed that depression of inhibitory neurotransmission in layer V was mediated by group III metabotropic glutamate receptors using a specific group III antagonist, (RS)-cyclopropyl-4-phosphonophenylglycine. Application of the antagonist alone did not alter the frequency of spontaneous neurotransmitter release, suggesting that the metabotropic glutamate receptor is not tonically active. In layer V of the entorhinal cortex, activation of presynaptic metabotropic glutamate receptors enhances spontaneous glutamate release, and inhibits spontaneous release of GABA. These effects may combine to increase random action potential firing in this layer, thereby reducing its capacity for synchrony generation. Our results are consistent with an anticonvulsant action for group III metabotropic glutamate receptors in the entorhinal cortex.

The role of group III metabotropic glutamate receptors (mGluRs) in modulating excitatory synaptic transmission was investigated in the rat entorhinal cortex (EC) in vitro. AMPA receptor-mediated excitatory postsynaptic currents (EPSCs) were recorded in the whole cell configuration of the patch-clamp technique from visually identified neurons in layers V and II. In layer V, bath application of the specific group III mGluR agonist L(+)-2-amino-4-phosphonobutyric acid (L-AP4, 500 microM) resulted in a marked facilitation of both spontaneous and activity-independent "miniature" (s/mEPSC) event frequency. The facilitatory effect of L-AP4 (100 microM) on sEPSC frequency prevailed in the presence of DL-2-amino-5-phosphonopentanoic acid (100 microM) but was abolished by the group III antagonist (RS)-cyclopropyl-4-phosphonophenylglycine (20 microM). These data confirmed that group III mGluRs, and not N-methyl-D-aspartate (NMDA) receptors were involved in the response to L-AP4. Bath application of the specific mGluR4a agonist (1S,3R,4S)-1-aminocyclopentane-1,2, 4-tricarboxylic acid (20 microM) also had a facilitatory effect on sEPSC frequency, suggesting involvement of mGluR4a. In layer II neurons, L-AP4 caused a reduction in sEPSC frequency but did not affect mEPSCs recorded in the presence of tetrodotoxin. These findings suggest that a group III mGluR with mGluR4a-like pharmacology is involved in modulating synaptic transmission in layer V cells of the EC. The effect on mEPSCs suggests that this receptor is located presynaptically and that its activation results in a direct facilitation of glutamate release. This novel facilitatory effect is specific to layer V and, to our knowledge, is the first report of a direct facilitatory action of group III mGluRs on synaptic transmission. In layer II, L-AP4 had an inhibitory effect on glutamate release similar to that reported in other brain regions.

The successful correction of infantile osteopetrosis in an Asian child by bone marrow transplantation (BMT) from an HLA-A,B matched cousin donor is reported. Retrospective HLA molecular analysis revealed that patient and donor were incompatible for HLA-DPB1. Donor type cells detected in the patient after transplantation indicate successful engraftment. The patient is currently alive and well.

Bone marrow transplantation (BMT) was carried out on 38 patients with thalassaemia major over a period of 9 years; 30 were Asian. In all cases, the donor was an HLA-identical relative. The mean age at transplant was 6.4 years (range 0.5-20 years). Conditioning was busulphan and cyclophosphamide (CY). Cyclosporin (CsA) (n = 30), CsA + methotrexate (n = 6) or CsA + T cell depletion (n = 2) were used for prophylaxis against graft-versus-host disease (GVHD). Thirty-four patients successfully engrafted. Two patients required a second transplant and two achieved mixed chimerism, eventually rejecting their grafts. Nine patients (23.6) developed acute GVHD grade III-IV. Eleven patients (28.9) developed chronic GVHD. There were 11 deaths, 7 within the first 100 days post-BMT. Twenty-seven patients are alive from 156 to 3213 days post-BMT. The actuarial survival at 9 years post-BMT was 70%. The mortality is higher than in previously reported series; possible reasons for this are discussed.

Five cases are reported of spontaneous remission of chronic childhood thrombocytopenia four or more years after diagnosis. Other than typical features of chronic idiopathic thrombocytopenic purpura there were no obvious markers predictive of late remission, although a slow progressive recovery was common to four of the patients. In light of this experience splenectomy is not recommended in clinically mild thrombocytopenia.

Ten haemophilia centres in northern Europe have pooled data on 202 haemophilic children who were infected with HIV between 1979 and 1986. All cases were under 16 years of age on 1 July 1985. The age at infection ranged from 1-15 years. Thirty seven cases (18%) had progressed to AIDS by 1 July 1991 and 15 of these have died. Persistent generalised lymphadenopathy has been noted in 102 patients of whom 18 (17%) have developed AIDS. Twenty three of the remaining patients (23%) have not. CD4+ T cell counts have fallen steadily. Of 36 patients who have had shingles since seroconversion, 19 (53%) had counts below 0.2 x 10(9)/l. Thirty five out of 145 patients without shingles (24%) had similar values. The mean IgA concentration in patients with CD4+ T cell counts above 0.5 x 10(9)/l was 2.38 g/l, between 0.2 and 0.5 was 3.07 g/l, and in those with CD4+ T cell counts below 0.2 x 10(9)/l the mean IgA concentration was 4.58 g/l. Treatment patterns have altered between 1989 and 1991, with increased use of zidovudine in patients without AIDS and a marked increase in primary prophylaxis against pneumocystis pneumonia. This has been associated with a decline in the incidence of pneumocystis as an indicator disease in new AIDS cases from 56% in 1989 to 20% in 1991. These observations indicate that persistent generalised lymphadenopathy does not worsen the outlook, but shingles does. Rising IgA concentrations are markers for disease progression. Modern prophylactic regimens are delaying the onset of indicator disease, but CD4 values continue to fall steadily.

Aims: To find out which children are treated with oral anticoagulants and how their treatment is controlled in the United Kingdom., Methods: Two questionnaires were used. The first was sent to general haematologists and the other to paediatric cardiologists and cardiac surgeons., Results: There were 273 (58%) replies to the first questionnaire. Most children were treated because of artificial cardiac valve replacement. The mean target International Normalised Ratio (INR) used was 2.73 to 4.0 for children with heart valves and 2.1 to 3.25 for children with venous thrombosis. The second questionnaire elicited replies from 11 of 22 cardiac centres. The mean target INR used for children with cardiac valves ranged from 2.59-3.77. Of 68 children covered in the survey, there have been two major bleeds and two thrombotic episodes: 78.8% of children were controlled with a venous prothrombin time and 21.2% with a capillary test. There was no consistency in the dose regimens used for the induction of oral anticoagulant treatment with warfarin., Conclusions: The levels of anticoagulation used for maintenance are similar to those recommended by the British Society for Haematology for adults (3.0 to 4.5). They seem to be safe for children too.

Neutropenia is a rare complication of Diamond-Blackfan syndrome (congenital hypoplastic anaemia). Three patients are reported: all had neutropenia as well as anaemia, and to investigate the cause of the neutropenia culture of bone marrow for granulocyte-macrophage colony forming cells (GMCFCs) was performed. Two cases had a low incidence of GMCFCs, but the third case had a high incidence. These findings suggest that myeloid precursors can be abnormal in Diamond-Blackfan syndrome and that the mechanism of neutropenia may, like that of anaemia, vary from patient to patient.

Congenital erythropoietic porphyria, a disorder of haem synthesis, is caused by uroporphyrinogen III synthase deficiency in bone-marrow normoblasts. Uroporphyrins and coproporphyrins accumulate and cause oxidative damage to cells exposed to sunlight. Uroporphyrin overproduction was greatly reduced and skin changes reversed in a girl who received a bone-marrow graft from an HLA-identical sibling at 10 years of age. The patient died 11 months after transplantation because of severe progressive pneumonitis and encephalopathy associated with cytomegalovirus infection, but the encouraging response up to 8 months after engraftment indicates a possible benefit of bone-marrow transplantation in the treatment of this rare but usually fatal inherited disease.

In a series of six cases of sex-linked agammaglobulinaemia neutropenia occurred as a presenting feature in four and during the presenting illness in the other two. The six patients all had low antibody titres and absent or low immunoglobulin concentrations with normal concentrations of T cells and absent B cells. The patients were all first seen with severe, acute infection, including septic abscesses and meningitis; neutropenia resolved as the infection and immunoglobulin deficiency were treated. Haematologists should be aware that neutropenia is a common association of infection in patients with immunoglobulin deficiency.

Two hundred and nine children presenting consecutively with acute lymphoblastic leukaemia to a regional paediatric oncology unit were investigated to determine the prognostic significance of various factors at diagnosis. There was a strong positive correlation between the pretreatment haemoglobin level and the percentage of bone marrow blast cells in S phase of the cell cycle as assessed by flow cytometry. Patients with T- and B-cell leukaemia had significantly higher haemoglobin levels than non-B non-T patients. In patients with total white cell counts less than 20 X 10(9)/l, aged less than 13 years, and no mediastinal mass, there was no association of haemoglobin with length of first remission. However, among those with white blood counts greater than 20 +/- 10(9)/l there was a strong positive trend towards shorter remission with higher haemoglobin levels. Children with high white blood counts at diagnosis and low haemoglobin levels may have a better prognosis than predicted by the white blood count alone.

A retrospective study of 50 patients with hereditary spherocytosis (HS) from 41 families seen between 1967 and 1979 at the Royal Manchester Children's Hospital, and Booth Hall Children's Hospital, Manchester, England is described. Nineteen patients (38%) had no family history of spherocytosis and in 12 patients (24%), tests on the family showed no evidence of disease. Various modes of inheritance are discussed in the light of these results. The traditional name for the condition (hereditary spherocytosis) is considered unsuitable as it is clearly inaccurate in many cases. The name congenital spherocytosis would be more appropriate.

Eighty-four children with acute lymphoblastic leukaemia (ALL) who had relapsed in bone marrow were studied to assess whether treatment would be more successful if relapse was detected before the disease became clinically evident. Patients whose relapse was detected by routine bone marrow examination before the disease became apparent were compared with those whose relapse was suspected from clinical examination or peripheral blood findings. In the former there was a lower percentage of blast cells in the marrow (p less than 0.02) and the patients suffered less from complications of the disease, but there was no difference in the incidence or duration of second remissions between the two groups.

Pretreatment marrow blast cells were studied in 38 boys and 27 girls (aged 1-14) with acute lymphoblastic leukaemia by flow cytometry after staining with propidium iodide.The percentage of blast cells in the S phase of the cell cycle ranged from 1% to 40% (median 6%). A correlation was found between the percentage of cells in S and the morphological classification of the French American British Cooperative Group (FAB), presence of T or B cell markers, haemoglobin concentration, blast size, bone pain, platelet count, and an inverse correlation with coarse granule and block staining with Periodic-acid-Schiff (PAS).63 of the 65 children attained complete remission. During the first 24 months of follow up there were fewer relapses (P = 0·054), and deaths (P = 0·004) in those children with 6% or fewer blasts in S phase. The difference was most marked in the first 12 months with 4 relapses out of 33 in the group with 6% or fewer cells in S compared with 13/30 in the group with > 6% cells in S.In order to investigate the prognostic significance of the pretreatment proliferative studies in greater detail, remission duration was correlated with 17 presenting features. Each feature was correlated individually and then the simultaneous effect of all the features was assessed by stepwise multiple regression.Only 3 features of the disease at diagnosis were individually correlated with duration of remission. These were% cells in S (P < 0·001), log white cell blood count (WBC) (P < 0·01) and the presence of T- or B-cell surface markers (P < 0·05). However, the multiple regression analysis showed that cell markers were not an independent prognostic feature, whereas the percentage cells in S and log WBC were independently and significantly correlated with duration of first remission (P < 0·001 in each case).