Binding of bromine-substituted analogs of methylphenidate to monoamine transporters

We synthesized the o-, m- and p-bromo derivatives of dl-threo-methylphenidate from the corresponding bromophenylacetonitriles by modification of the literature synthesis of methylphenidate (Panizzon, Helv. Chim. Acta 1944, 27, 1748). In in vitro binding assays all three dl-threo bromo compounds had higher affinities than methylphenidate for dopamine transporter sites labeled with [3H]2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane ([3H]WIN 35,428; IC50 = 13, 4, 20 and 82 nM for o-, m-, and p-bromo compounds, and unsubstituted methylphenidate, respectively). They also bound more strongly than methylphenidate to norepinephrine reuptake sites labeled with [3H]nisoxetine (IC50 = 32, 20, 31 and 440 nM, respectively), but were weak ligands (IC50 > or = 1 microM) at the serotonin transporter labeled with [3H]paroxetine. In addition, the bromine substituted derivatives demonstrated similar activity to methylphenidate in vivo in rodents in terms of inhibition of heart uptake of [3H](-)-norepinephrine, elevation of striatal extracellular dopamine, and stimulation of locomotor activity.

Gene trees and hominoid phylogeny

Here we present a DNA sequence study that incorporates intraspecific variation from all five genera of hominoids (apes and humans). Recently it has been claimed that using single individuals to analyze species' relationships might be misleading if within-species variation is great. Our results indicate that despite high intraspecific variation in mitochondrial cytochrome oxidase subunit II gene sequences of some hominoids, humans and chimpanzees are nonetheless significantly most closely related. We also report the observation that variation within the gorilla species exceeds that between common and pygmy chimpanzee species, a finding with implications for conservation. In contrast, humans are less mitochondrially diverse than lowland gorillas inhabiting western Africa.

The bipartite D. melanogaster twist promoter is reorganized in D. virilis

The pivotal role of twist in mesoderm determination in the Drosophila embryo depends upon two processes--the transcriptional activation of twist in the ventrally located mesodermal anlage and the regulation of downstream gene expression by the twist transcription factor. To elucidate the molecular mechanisms involved in these processes, we have compared both the coding and regulatory regions of the twist genes from Drosophila melanogaster and Drosophila virilis. Within the coding region, the basic-helix-loop-helix DNA binding and dimerization motif is highly conserved, consistent with the functional importance of this domain. A comparison of the transcriptional regulatory regions reveals a high degree of conservation in the more distal of the two ventral activator regions that have been mapped in the twist 5' flanking region. On the other hand, the more proximal ventral activator region is absent at the corresponding position in the D. virilis twist gene. Instead, there is a region in the second intron of the D. virilis gene that resembles the proximal element of the D. melanogaster gene, in that it consists of little more than a series of whole and half binding sites for the dorsal morphogen. In transformation experiments, the intronic D. virilis element directs an expression pattern that is indistinguishable from that directed by the D. melanogaster proximal VAR. Thus, the twi genes from these two species appear to have evolved enhancer elements with very similar structural and functional properties. These findings suggest that apparently redundant spatially regulated enhancer elements may each play essential roles in fine tuning the level and/or pattern of gene expression.

Analysis of polycyclic aromatic hydrocarbons in cooking oil fumes

Various samples of cooking oil fumes were analyzed to an effort to study the relationship between the high incidence of pulmonary adenocarcinoma in Chinese women and cooking oil fumes in the kitchen. Polycyclic aromatic hydrocarbons (PAHs) in samples of cooking oil fumes were extracted, chromatographed, and measured by fluorescence spectrophotometer. The samples included oil fumes from three commercial cooking oils and fumes from three catering shops. All samples contained benzo(a)pyrene (BaP) and dibenzo (a,h)anthracene (DBahA). In addition, the concentration of DBahA was 5.7 to 22.8 times higher than that of BaP in the fume samples. Concentrations of BaP and DBahA were, respectively, 0.463 and 5.736 micrograms/g in refined vegetable oil, 0.341 and 3.725 micrograms/g in soybean oil, and 0.305 and 4.565 micrograms/g in vegetable oil. Investigation of PAH concentrations at three catering shops showed that the level of BaP at a Youtiao (deep-fried twisted dough sticks) shop was 4.18 micrograms/100 m3, 2.28 micrograms/100 m3 at a Seqenma (candied fritters) workshop, and 0.49 micrograms/100 m3 at a kitchen of a restaurant; concentrations of DBahA were 33.80, 14.41, and 3.03 micrograms/100 m3, respectively. The high concentration of carcinogens, such as BaP and DBahA, in cooking oil fumes might help explain why Chinese women, who spend more time exposed to cooking oil fumes than men, have a high incidence of pulmonary adenocarcinoma.

Evidence that the major membrane lipids, except cholesterol, are made in axons of cultured rat sympathetic neurons

Membrane lipids and proteins required for axonal growth and regeneration are generally believed to be synthesized in the cell bodies of neurons and transported into the axons. However, we have demonstrated recently that, in cultured rat sympathetic neurons, axons themselves have the capacity to synthesize phosphatidylcholine, sphingomyelin, and phosphatidylethanolamine. In these experiments, we employed a compartment model of neuron culture in which pure axons grow in a fluid environment separate from that containing the cell bodies. In the present study, we again used compartmented cultures to confirm and extend the previous results. We have shown that three enzymes of phosphatidylcholine biosynthesis via the CDP-choline pathway are present in axons. We have also shown that the rate-limiting step in the biosynthesis of phosphatidylcholine by this route in neurons, and locally in axons, is catalyzed by the enzyme CTP:phosphocholine cytidylytransferase. The biosynthesis of other membrane lipids, such as phosphatidylserine, phosphatidylethanolamine derived by decarboxylation of phosphatidylserine, phosphatidylinositol, and fatty acids, also occurs in axons. However, the methylation pathway for the conversion of phosphatidylethanolamine into phosphatidylcholine appears to be a quantitatively insignificant route for phosphatidylcholine synthesis in neurons. Moreover, our data provided no evidence for the biosynthesis of another important membrane lipid, cholesterol, in axons.

Mitochondrial COII sequences and modern human origins

The aim of this study is to measure human mitochondrial sequence variability in the relatively slowly evolving mitochondrial gene cytochrome oxidase subunit II (COII) and to estimate when the human common ancestral mitochondrial type existed. New COII gene sequences were determined for five humans (Homo sapiens), including some of the most mitochondrially divergent humans known; for two pygmy chimpanzees (Pan paniscus); and for a common chimpanzee (P. troglodytes). COII sequences were analyzed with those from another relatively slowly evolving mitochondrial region (ND4-5). From class 1 (third codon position) sequence data, a relative divergence date for the human mitochondrial ancestor is estimated as 1/27 th of the human-chimpanzee divergence time. If it is assumed that humans and chimpanzees diverged 6 Mya, this places a human mitochondrial ancestor at 222,000 years, significantly different from 1 Myr (the presumed time of an H. erectus emergence from Africa). The mean coalescent time estimated from all 1,580 sites of combined mitochondrial data, when a 6-Mya human-chimpanzee divergence is assumed, is 298,000 years, with 95% confidence interval of 129,000-536,000 years. Neither estimate is compatible with a 1-Myr-old human mitochondrial ancestor. The mitochondrial DNA sequence data from COII and ND4-5 regions therefore do not support this multiregional hypothesis for the emergence of modern humans.

6q deletions define distinct clinico-pathologic subsets of non-Hodgkin's lymphoma

Commonly observed in lymphoid neoplasms, deletions of 6q have been correlated with histologic and clinical subsets of non-Hodgkin's lymphoma (NHL). Our recent analysis of loss of heterozygosity of 6q loci in NHL showed two regions of minimal molecular deletion (RMD), an RMD1 at 6q25-27 and an RMD2 at 6q21-23. To establish correlations between these RMDs and regions of minimal cytogenetic deletions (RCDs) on 6q, and to define associations between RCDs and clinico-pathologic features, we have analyzed chromosome 6 abnormalities in 459 consecutively ascertained, karyotypically abnormal cases of NHL. Among these, 126 (27.5%) cases had structural abnormalities of chromosome 6, of which 94 were deletions. Analysis of these deletions identified three RCDs. An RCD1 encompassing 6q25-27 was seen in 45 intermediate-grade NHL. An RCD2 at 6q21 was observed in 11 high-grade NHL, 9 of which were of the immunoblastic subtype. An RCD3 at 6q23 was noted in 18 low-grade NHL lacking a t(14;18) translocation. Of these 18 cases, 12 were small lymphocytic NHL and, in 2 of these, del(6q) was the sole karyotypic abnormality. In 20 cases of low-grade NHL with t(14;18), the deletions spanned both RCD1 and RCD3. These data suggested the presence of at least 3 tumor suppressor genes on 6q within RCD1, RCD2, and RCD3; they also showed associations between RCDs in 6q and subsets of NHL, including a specific association between a group of well-differentiated lymphoid neoplasms and RCD3. The apparent heterogeneity of breakpoints when all NHLs are considered together explains the inability of previous studies to reliably establish correlations between recurring 6q deletions and histologic and clinical features of NHL.

The same dorsal binding site mediates both activation and repression in a context-dependent manner

Like many DNA binding transcription factors, the Drosophila morphogen encoded by dorsal can both stimulate and repress promoter activity. In particular, this factor activates twist and represses zerknüllt on the ventral side of the early embryo. We find that when multiple copies of a dorsal binding site from the zerknüllt ventral repressor element are fused to a heterologous basal promoter, the resulting construct is activated by dorsal to give a ventral specific expression pattern. Thus, the ability of a dorsal binding site to mediate repression rather than activation is not an intrinsic property of the site, but depends upon its context. We also show that a hybrid promoter containing both the zerknüllt ventral repressor element and the twist ventral activator region is not ventrally active in the early embryo, demonstrating that repression is dominant over activation. Thus, the default mode of action of the dorsal protein is transcriptional activation. Additional factors may modify dorsal activity to bring about repression.

Biosynthesis of membrane lipids in rat axons

Compartmented cultures of sympathetic neurons from newborn rats were employed to test the hypothesis that the lipids required for maintenance and growth of axonal membranes must be synthesized in the cell body and transported to the axons. In compartmented cultures the distal axons grow into a compartment separate from that containing the cell bodies and proximal axons, in an environment free from other contaminating cells such as glial cells and fibroblasts. There is virtually no bulk flow of culture medium or small molecules between the cell body and axonal compartments. When [methyl-3H]choline was added to the cell body-containing compartment the biosynthesis of [3H]-labeled phosphatidylcholine and sphingomyelin occurred in that compartment, with a gradual transfer of lipids (less than 5% after 16 h) into the axonal compartment. Surprisingly, addition of [methyl-3H]choline to the compartment containing only the distal axons resulted in the rapid incorporation of label into phosphatidylcholine and sphingomyelin in that compartment. Little retrograde transport of labeled phosphatidylcholine and sphingomyelin (less than 15%) into the cell body compartment occurred. Moreover, there was minimal transport of the aqueous precursors of these phospholipids (e.g., choline, phosphocholine and CDP-choline) between cell compartments. Similarly, when [3H]ethanolamine was used as a phospholipid precursor, the biosynthesis of phosphatidylethanolamine occurred in the pure axons, and approximately 10% of the phosphatidylethanolamine was converted into phosphatidylcholine. Experiments with [35S]methionine demonstrated that proteins were made in the cell bodies, but not in the axons. We conclude that axons of rat sympathetic neurons have the capacity to synthesize membrane phospholipids. Thus, a significant fraction of the phospholipids supplied to the membrane during axonal growth may be synthesized locally within the growing axon.

Many maize inbreds lack an endosperm cytosolic phosphoglucomutase

Starch gel electrophoresis of extracts from developing maize (Zea mays L.) endosperms 22 days postpollination reveals only a single zone of phosphoglucomutase activity in the majority of the inbreds tested. The other inbreds had the expected two zones of activity. The activity that is present in all inbreds is the amyloplast isozyme while the absent form is a cytosolic enzyme. The lack of the cytosolic isozyme has no discernible phenotypic consequences.

A debranching enzyme deficiency in endosperms of the sugary-1 mutants of maize

Many of the sugary-1 mutants of maize (Zea mays L.) have the highly branched water-soluble polysaccharide, phytoglycogen, in quantities equal to or greater than starch as an endosperm storage product in mature seeds. We find that all sugary mutants investigated are deficient in debranching enzyme [alpha-(1, 6)-glucosidase] activity in endosperm tissue 23 days postpollination and suggest that this deficiency is the primary biochemical lesion leading to phytoglycogen accumulation in sugary endosperms. This would indicate that the amylopectin component of starch depends on an equilibrium between the activities of branching enzymes introducing alpha-1,6 branch points into the linear alpha-1,4 glucans and debranching enzymes. The debranching enzyme activities from nonsugary endosperms can be separated into three peaks on a hydroxyapatite column. The sugary endosperm extracts lack one of these peaks of activity while the other two fractions have much reduced activity. The embryos of developing seeds (23 days after pollination) from both sugary and nonsugary genotypes have equivalent debranching activity. The debranching enzyme activity of developing endosperms is proportional to the number of copies (0 to 3) of the nonmutant (Su) allele present suggesting that the Su allele may be the structural gene for this debranching enzyme, although this is not definitive. This identification of debranching enzyme activity as being the biochemical lesion in sugary endosperms is consistent with several previous observations on the mutant.

Specific immunosuppression of IgE response to hapten DNP by linked to monoclonal IgG1 in rats

The induction of the anti-DNP IgE in rat was suppressed by pretreatment of rats with the tolerogen synthesized by coupling DNP to rat IgG, i.e.; DNP7-10-IgG. It was found that DNP10-IgG1 was an effective tolerogen, whereas other DNP conjugates, i.e. DNP9-IgM, DNP9-IgA, DNP10-IgE, DNP10-IgG2c and DNP10-IgG2a were ineffective.