Development of tyrosine hydroxylase-, dopamine- and dopamine β-hydroxylase-immunoreactive neurons in a teleost, the three-spined stickleback

The development of catecholaminergic neuronal systems in the brain of a teleost, the three-spined stickleback, was studied through embryonic to early larval stages by immunocytochemistry using specific antibodies against dopamine, tyrosine hydroxylase and dopamine β-hydroxylase. By analysing the spatiotemporal patterns of development for the catecholaminergic nuclei, possible homologies with nuclei in amniote brains have been identified.

The noradrenergic neurons in the isthmus region of the rostral rhombencephalon originate in the same manner as the A4–A7 + subcoeruleus group in mammals. Their developmental characteristics show the largest similarities with the subcoeruleus group of birds and mammals, although some features are shared with developing A6 (locus coeruleus) neurons.

Catecholaminergic neurons never appear during development in the ventral mesencephalon of the three-spined stickleback. A group of large dopaminergic neurons that accompany the cerebrospinal fluid (CSF)-contacting neurons follows the border between the hypothalamus and the ventral thalamus into the caudal hypothalamus, where they are continuous with the dopaminergic neurons in the posterior tuberculum. They are thus topologically comparable with the dopaminergic neurons of the zona incerta in mammals.

The dopaminergic CSF-contacting neurons that line the median, lateral and posterior recesses of the third ventricle do not contain tyrosine hydroxylase-immunoreactivity at any developmental stage. This indicates that they take up and accumulate exogenous dopamine or -dihydroxyphenylalanine, and do not synthesize dopamine from tyrosine at any developmental stage. Tyrosine hydroxylase-immunoreactive neurons appear in the pineal organ on the day of hatching (120 h post-fertilization). They were still observed in 240-h-old larvae, but are absent in the pineal organ of adult sticklebacks.

The initial appearance and subsequent differentiation of catecholaminergic neurons in the stickle-back embryo follow essentially the same spatial and temporal pattern as in amphibian, avian and mammalian embryos. This observation supports the hypothesis that morphologically, topologically and chemically similar monoaminergic neurons in different vertebrate classes are homologous.     

Elevated red cell adenosine deaminase activity: a marker of disordered erythropoiesis in Diamond-Blackfan anaemia and other haematologic diseases

Red-cell adenosine deaminase (ADA) activity in children with Diamond-Blackfan anaemia is significantly increased (1.91 +/- 0.90 U/g Hb) compared to that seen in transient erythroblastopenia of childhood (0.80 +/- 0.16 U/g Hb) or normal individuals (0.61 +/- 0.13 U/g). These data thus further support that measurement of this purine metabolic enzyme is useful in diagnosing the cause of pure RBC aplasia in children. Of interest, however, elevated RBC-ADA activity also is seen in some children with acute leukaemia and other haematologic disorders. In children with acute lymphoblastic leukaemia (ALL), the increase in RBC-ADA activity is proportional to the degree of anaemia. However, the elevated RBC-ADA activity in this leukaemic population is not related to the fetal haemoglobin concentration. These data suggest increased RBC-ADA activity may be a non-specific manifestation of abnormal erythroid stem cell function, an alteration distinct from that seen with reactivation of fetal erythropoiesis. However, since almost all patients with Diamond-Blackfan anaemia manifest elevated RBC-ADA activity, this chemical alteration yet may reflect the specific erythroid differentiation lesion in this disorder.     

Sleep and its homeostatic regulation in mice lacking the adenosine A1 receptor

Sleep deprivation (SD) increases extracellular adenosine levels in the basal forebrain, and pharmacological manipulations that increase extracellular adenosine in the same area promote sleep. As pharmacological evidence indicates that the effect is mediated through adenosine A1 receptors (A1R), we expected A1R knockout (KO) mice to have reduced rebound sleep after SD. Male homozygous A1R KO mice, wild-type (WT) mice, and heterozygotes (HET) from a mixed 129/C57BL background were implanted during anesthesia with electrodes for electroencephalography (EEG) and electromyography (EMG). After 1 week of recovery, they were allowed to adapt to recording leads for 2 weeks. EEG and EMG were recorded continuously. All genotypes had a pronounced diurnal sleep/wake rhythm after 2 weeks of adaptation. We then analyzed 24 h of baseline recording, 6 h of SD starting at light onset, and 42 h of recovery recording. Neither rapid eye movement sleep (REM sleep) nor non-REM sleep (NREMS) amounts differed significantly between the groups. SD for 6 h induced a strong NREMS rebound in all three groups. NREMS time and accumulated EEG delta power were equal in WT, HET and KO. Systemic administration of the selective A1R antagonist 8-cyclopentyltheophylline (8-CPT) inhibited sleep for 30 min in WT, whereas saline and 8-CPT both inhibited sleep in KO. We conclude that constitutional lack of adenosine A1R does not prevent the homeostatic regulation of sleep.     

Trisomy 8 as the sole chromosomal aberration in myelocytic malignancies: a multicolor and locus-specific fluorescence in situ hybridization study

Trisomy 8 is the most common chromosomal aberration in myelocytic malignancies, occurring both as a sole change as well as in addition to other abnormalities. In spite of this, next to nothing is known about its pathogenetic importance or its molecular genetic consequences. Possible mechanisms involved in the transformation process include dosage effects of genes mapping to chromosome 8 and presence of specific mutations or cryptic fusion genes on the duplicated chromosome. In the latter case, +8 would be secondary to a cryptic primary rearrangement and not involved in leukemogenesis as such, but rather in tumor evolution. Although hidden genetic changes have been found in some trisomies, for example, mutations in KIT in acute myelocytic leukemia (AML) with +4 and in MET in hereditary papillary kidney carcinoma with trisomy 7, none associated with +8 have so far been discovered. To address this issue, we have investigated a total of 13 cases of AML, myelodysplastic syndromes, and chronic myeloproliferative disorders with trisomy 8 as the sole chromosomal anomaly. All cases were studied by combined binary ratio multicolor fluorescence in situ hybridization (FISH) and with FISH using locus-specific probes for both arms of chromosome 8, the subtelomeric regions of 8p and 8q, and the leukemia-associated genes FGFR1, MOZ, ETO, and MYC. No cryptic changes were detected, thus excluding the possibility of gross genetic rearrangements or aberrations involving these loci on chromosome 8.     

Interaction of Adenosine 5‘-Triphosphate (ATP) with Histamine Release Induced by Compound 48/80

The histamine releasing action of compound 48/80 disappeared after pretreatment of rat mast cells with ATP in the absence of divalent cations. The inhibitory action was evident already with 2 μM of ATP, provided the cells were preincubated with ATP for short periods of time prior to the addition of 48/80. When mast cells were exposed to 48/80 combined with ATP more than 10 μM of ATP was needed to induce inhibition of histamine release. This inhibitory effect was found to be specific for ATP compared with various organic phosphorous compounds tested and was not mimicked by EDTA. With concentrations of ATP less than 10 μM the sensitivity to the action of 48/80 was spontaneously restored after prolonged preincubation of the cells with ATP. The experimental findings suggest that ATP, in the absence of divalent cations, induced configurational changes of the plasma membrane of the mast cells so that 48/80 could no longer exert its degranulating and histamine releasing action.     

Isolation of human immunodeficiency virus (HIV) from plasma during primary HIV infection

Human immunodeficiency virus (HIV) has been isolated from plasma in 6 of 7 patients showing clinical symptoms of a primary HIV infection. Parallel cultures from peripheral blood mononuclear cells (PBMC) yielded virus in 5 patients. In one case, virus could only be isolated from the cerebrospinal fluid but not from peripheral blood. Detectable viremia was transient and preceded the appearance of HIV specific antibodies. After cessation of acute symptoms, the frequency of HIV isolations was similar to that of asymptomatic carriers (23 and 26%, respectively). The role of the immune response in terminating detectable viremia remains to be established.     

Hereditary multiple and isolated sporadic exostoses in the same kindred: identification of the causative gene (EXT2) and detection of a new mutation, nt112delAT, that distinguishes the two phenotypes

Hereditary multiple exostoses (HME) is a well known autosomal dominant hereditary orthopedic disorder. Isolated exostoses, on the other hand, occur as sporadic events or as secondary post-traumatic sequel. The occurrence of solitary exostoses in individuals from pedigrees affected with HME may distort conclusions about carrier status and/or diagnosis. Both conditions are potentially malignant and both are associated with genetic alterations in either EXT1 or EXT2 genes. In this study, we present a seven-generation family from western Sweden consisting of 170 blood relatives, 38 of whom had multiple cartilaginous exostoses, while 8 had isolated exostoses. Linkage analysis aimed to discern one of the known EXT genes demonstrated linkage of the HME phenotype to the EXT2 gene. Subsequent mutation analysis revealed a novel mutation, nt112delAT, in this gene. All carriers of the detected mutation had multiple exostoses, indicating full penetrance. None of the pedigree members with isolated exostoses were carriers of the detected mutation. Two of the mutation carriers developed chondrosarcoma yielding a 5.2% risk of malignant development for this mutation. The detection of this mutation has enabled us to provide appropriate genetic counseling concerning this complex situation.