bluuebunny/crossref_metadata_2025 huggingface dataset:
Conservation in budding yeast of a kinase specific for SR splicing factors
Authors: Siebel Christian W. , Feng Lana , Guthrie Christine , Fu Xiang-Dong
Published: July 2002

SR protein kinases (SRPKs) and their substrates, the SR family of serine/arginine-rich pre-mRNA splicing factors, appear to be key regulators of alternative splicing. Although SR proteins have been well characterized through biochemical experiments in metazoans, their functions
in vivo
are unclear. Because of the strict splice site consensus and near absence of alternative splicing in
Saccharomyces cerevisiae
, it had been thought that budding yeast would lack an SRPK and its substrates. Here, we present structural, biochemical, and cell-biological evidence that directly demonstrates an SR protein kinase, Sky1p, as well as a number of SRPK substrates in
S. cerevisiae
. One of these substrates is Npl3p, an SR-like protein involved in mRNA export. This finding raises the provocative possibility that Sky1p, and by extension metazoan SRPKs, regulates mRNA export or the nucleocytoplasmic shuttling of RS domain proteins. The unexpected discovery of an SR protein kinase in budding yeast provides a foundation for genetic dissection of the biological functions of SR proteins and their kinases.
Rapid p53 sequence analysis in primary lung cancer using an oligonucleotide probe array
Authors: Ahrendt Steven A. , Halachmi Sarel , Chow John T. , Wu Li , Halachmi Naomi , Yang Stephen C. , Wehage Scott , Jen Jin , Sidransky David
Published: July 2002

The p53 gene was sequenced in 100 primary human lung cancers by using direct dideoxynucleotide cycle sequencing and compared with sequence analysis by using the p53 GeneChip assay. Differences in sequence analysis between the two techniques were further evaluated to determine the accuracy and limitations of each method. p53 mutations were either detected by using both techniques or, if only detected by one technique, were confirmed by using mutation-specific oligonucleotide hybridization. Dideoxynucleotide sequencing of the conserved regions of the p53 gene (exons 5–9) detected 76% of the mutations within this region of the gene. The GeneChip p53 assay detected 81% of all (exons 2–11) mutations, including 80% of the mutations within the conserved regions of the gene. The GeneChip assay detected 46 of 52 missense mutations (88%), but 0 of 5 frameshift mutations. The specificity of direct sequencing and of the p53 GeneChip assay at detecting p53 mutations were 100% and 98%, respectively. The GeneChip p53 assay is a rapid and reasonably accurate approach for detecting p53 mutations; however, neither direct sequencing nor the p53 GeneChip are infallible at p53 mutation detection.
The spinal biology in humans and animals of pain states generated by persistent small afferent input
Authors: Yaksh Tony L. , Hua Xiao-Ying , Kalcheva Iveta , Nozaki-Taguchi Natsuko , Marsala Martin
Published: July 2002

Behavioral models indicate that persistent small afferent input, as
generated by tissue injury, results in a hyperalgesia at the site of
injury and a tactile allodynia in areas adjacent to the injury site.
Hyperalgesia reflects a sensitization of the peripheral terminal and a
central facilitation evoked by the persistent small afferent input. The
allodynia reflects a central sensitization. The spinal pharmacology of
these pain states has been defined in the unanesthetized rat prepared
with spinal catheters for injection and dialysis. After tissue injury,
excitatory transmitters (e.g., glutamate and substance P) acting though
N-
methyl-
d
-aspartate (NMDA) and neurokinin 1
receptors initiate a cascade that evokes release of (
i
) NO,
(
ii
) cyclooxygenase products, and (
iii
)
activation of several kinases. Spinal dialysis show amino acid and
prostanoid release after cutaneous injury. Spinal neurokinin 1, NMDA,
and non-NMDA receptors enhance spinal prostaglandin E2 release. Spinal
prostaglandins facilitate release of spinal amino acids and peptides.
Activation by intrathecal injection of receptors on spinal C fiber
terminals (μ,/∂ opiate, α2 adrenergic, neuropeptide Y) prevents
release of primary afferent peptides and spinal amino acids and blocks
acute and facilitated pain states. Conversely, consistent with their
role in facilitated processing, NMDA, cyclooxygenase 2, and NO synthase
inhibitors act to diminish only hyperalgesia. Importantly, spinal
delivery of several of these agents diminishes human injury pain
states. This efficacy emphasizes (
i
) the role of
facilitated states in humans, (
ii
) shows the importance of
spinal systems in human pain processing, and (
iii
)
indicates that these preclinical mechanisms reflect processes that
regulate the human pain experience.
Control of separate pathogenic autoantibody responses marks MHC gene contributions to murine lupus
Authors: Vyse Timothy J. , Halterman Richard K. , Rozzo Stephen J. , Izui Shozo , Kotzin Brian L.
Published: July 2002

Previous studies have suggested that MHC and non-MHC genes contribute to the development of autoimmune disease in F1hybrids of New Zealand black (NZB) and white (NZW) mice. We conducted a genome-wide screen of 148 female (NZB × NZW)F1× NZB backcross mice to map dominant NZW genetic loci linked with lupus disease traits. In this backcross analysis, inheritance of the NZW MHC (H2d/zvs.H2d/d) was strongly linked with the development of lupus nephritis (P≈ 1 × 10−16), increasing the risk of disease by over 30-fold.H2d/zwas also linked with elevated serum levels of IgG autoantibodies to single-stranded DNA, double-stranded DNA, histones, and chromatin but not with anti-gp70 autoantibodies, measured as circulating gp70–anti-gp70 immune complexes. Non-MHC contributions from NZW seemed weak in comparison to MHC, although NZW loci on chromosomes 7 and 16 were noted to be suggestively linked with autoantibody production. Strikingly,H2d/z(compared withH2d/d) enhanced antinuclear antibodies in a coordinate fashion but did not affect anti-gp70 production in the current backcross. However, the opposite influence was noted forH2d/z(compared withH2z/z) when (NZB × NZW)F1× NZW backcross mice were analyzed. These results suggest thatH2zandH2dhaplotypes differentially regulate two different sets of nephritogenic autoantibody responses. This study confirms a critical role forH2zcompared with other dominant NZW loci in (NZB × NZW)F1mice and provides an explanation as to whyH2d/zheterozygosity is required for full expression of disease in this model.
Resolution of concerted versus sequential mechanisms in photo-induced double-proton transfer reaction in 7-azaindole H-bonded dimer
Authors: Catalán Javier , del Valle Juan Carlos , Kasha Michael
Published: July 2002

The experimental and theoretical bases for a synchronous or concerted double-proton transfer in centro-symmetric H-bonded electronically excited molecular dimers are presented. The prototype model is the 7-azaindole dimer. New research offers confirmation of a concerted mechanism for excited-state biprotonic transfer. Recent femtosecond photoionization and coulombic explosion techniques have given rise to time-of-flight MS observations suggesting sequential two-step biprotonic transfer for the same dimer. We interpret the overall species observed in the time-of-flight experiments as explicable without conflict with the concerted mechanism of proton transfer.
A comparison of T cell memory against the same antigen induced by virus versus intracellular bacteria
Authors: Ochsenbein Adrian F. , Karrer Urs , Klenerman Paul , Althage Alana , Ciurea Adrian , Shen Hao , Miller Jeff F. , Whitton J. Lindsay , Hengartner Hans , Zinkernagel Rolf M.
Published: July 2002

Cytotoxic T cell (CTL) memory was analyzed after infection with lymphocytic choriomeningitis virus (LCMV) and recombinantListeria monocytogenes(rLM) expressing the complete nucleoprotein of LCMV (rLM-NPactA) or only the immunodominant epitope of H-2dmice (rLM-NP118–126). Immunization with LCMV and rLM induced a long-lived increased CTL precursor (CTLp) frequency specific for the viral (NP118–126) and for the bacterial (LLO91–99) epitope, respectively. However, after infection with rLM memory, CTLs were less protective against an intravenous LCMV challenge infection than a comparable number of LCMV-induced memory T cells. LCMV, but not recombinantListeria-induced memory T cells were able to protect against lethal choriomeningitis by LCMV or a subsequent peripheral infection with recombinant vaccinia virus expressing LCMV-NP. The protective memory after viral and after rLM immunization was paralleled by evidence of LCMV but not rLM antigen persistence on day 15 and 30 after vaccination. These results document a striking difference in protective T cell memory between viral and bacterial vaccines and indicate that rapid T cell-dependent immune protection correlates with antigen persistence.
A mechanism for Rb/p130-mediated transcription repression involving recruitment of the CtBP corepressor
Authors: Meloni Alison R. , Smith Eric J. , Nevins Joseph R.
Published: July 2002

Previous work has demonstrated the critical role for transcription repression in quiescent cells through the action of E2F-Rb or E2F-p130 complexes. Recent studies have shown that at least one mechanism for this repression involves the recruitment of histone deacetylase. Nevertheless, these studies also suggest that other events likely contribute to E2F/Rb-mediated repression. Using a yeast two-hybrid screen to identify proteins that specifically interact with the Rb-related p130 protein, we demonstrate that p130, as well as Rb, interacts with a protein known as CtIP. This interaction depends on the p130 pocket domain, which is important for repression activity, as well as an LXCXE sequence within CtIP, a motif previously shown to mediate interactions of viral proteins with Rb. CtIP interacts with CtBP, a protein named for its ability to interact with the C-terminal sequences of adenovirus E1A. Recent work has demonstrated that the
Drosophila
homologue of CtBP is a transcriptional corepressor for Hairy, Knirps, and Snail. We now show that both CtIP and CtBP can efficiently repress transcription when recruited to a promoter by the Gal4 DNA binding domain, thereby identifying them as corepressor proteins. Moreover, the full repression activity of CtIP requires a PLDLS domain that is also necessary for the interaction with CtBP. We propose that E2F-mediated repression involves at least two events, either the recruitment of a histone deacetylase or the recruitment of the CtIP/CtBP corepressor complex.
Derived variables for longitudinal studies
Authors: Cox D. R. , Wermuth Nanny
Published: July 2002

Suppose that for each individual a vector of features is measured at a number of time points. We look for a transformation of the features, the same at all time points, that will induce a simple dependency structure. In the simplest situation this requires that a certain asymmetric matrix has real nonzero eigenvalues. Extensions are considered.
The chitinase PfCHT1 from the human malaria parasite
Plasmodium falciparum
lacks proenzyme and chitin-binding domains and displays unique substrate preferences
Authors: Vinetz Joseph M. , Dave Sanat K. , Specht Charles A. , Brameld Kenneth A. , Xu Bo , Hayward Rhian , Fidock David A.
Published: July 2002

Within hours after the ingestion of a blood meal, the mosquito midgut epithelium synthesizes a chitinous sac, the peritrophic matrix.
Plasmodium
ookinetes traverse the peritrophic matrix while escaping the mosquito midgut. Chitinases (EC
3.2.1.14
) are critical for parasite invasion of the midgut: the presence of the chitinase inhibitor, allosamidin, in an infectious blood meal prevents oocyst development. A chitinase gene, PgCHT1, recently has been identified in the avian malaria parasite
P. gallinaceum
. We used the sequence of PgCHT1 to identify a
P. falciparum
chitinase gene, PfCHT1, in the
P. falciparum
genome database. PfCHT1 differs from PgCHT1 in that the
P. falciparum
gene lacks proenzyme and chitin-binding domains. PfCHT1 was expressed as an active recombinant enzyme in
Escherichia coli
. PfCHT1 shares with PgCHT1 a substrate preference unique to
Plasmodium
chitinases: the enzymes cleave tri- and tetramers of GlcNAc from penta- and hexameric oligomers and are unable to cleave smaller native chitin oligosaccharides. The pH activity profile of PfCHT1 and its IC
50
(40 nM) to allosamidin are distinct from endochitinase activities secreted by
P. gallinaceum
ookinetes. Homology modeling predicts that PgCHT1 has a novel pocket in the catalytic active site that PfCHT1 lacks, which may explain the differential sensitivity of PfCHT1 and PgCHT1 to allosamidin. PfCHT1 may be the ortholog of a second, as yet unidentified, chitinase gene of
P. gallinaceum
. These results may allow us to develop novel strategies of blocking human malaria transmission based on interfering with
P. falciparum
chitinase.
Theoretical investigation of the [1,2]-sigmatropic hydrogen migration in the mechanism of oxidation of 2-aminobenzoyl-CoA by 2-aminobenzoyl-CoA monooxygenase/reductase
Authors: Torres Rhonda A. , Bruice Thomas C.
Published: July 2002

The flavin hydroperoxide at the active site of the mixed-function oxidase 2-aminobenzoyl-CoA monooxygenase/reductase (
Azoarcus evansii
) transfers an oxygen to the 5-position of the 2-aminobenzoyl-CoA substrate to provide the alkoxide intermediate II
−
. Hydrogen migration from C5 to C6 follows this monooxygenation. The nature of the monooxygenation intermediate and plausible competing reactions leading to hydrogen migration have been considered.
Ab initio
molecular orbital theory has been used to calculate structures and electron distributions in intermediate and transition state structures. Electrostatic potential surface calculations establish that the transition state and product, associated with the C5 to C6 hydrogen transfer, are stabilized by electron distribution to the benzoyl-CoA thioester carbonyl oxygen. This is not so for the transition state and product associated with hydrogen transfer from C5 to C4. The activation energy for the 5,6-shift is 2.5 kcal/mol lower than that for the 5,4-shift. In addition, the product of the hydrogen 5,6-shift is more stable than is the product of the hydrogen 5,4-shift, by ≈6 kcal/mol. These results explain why only the shift of hydrogen from C5 to C6 is observed experimentally. Oxygen transfer and hydrogen migration almost coincide in the gas phase (activation energy of ≈0.6 kcal/mol, equivalent to a single bond vibration). Enzymatic formation of alkoxide II
−
requires its stabilization; thus, the rate constant for its breakdown would be slower than in the gas phase.
Catalytic subunit of DNA-dependent protein kinase: Impact on lymphocyte development and tumorigenesis
Authors: Kurimasa Akihiro , Ouyang Honghai , Dong Li-jin , Wang Sa , Li Xiaoling , Cordon-Cardo Carlos , Chen David J. , Li Gloria C.
Published: July 2002

The DNA-dependent protein kinase (DNA-PK) consists of a heterodimer
DNA-binding complex, Ku70 and Ku80, and a large catalytic subunit,
DNA-PKcs. To examine the role of DNA-PKcs in lymphocyte development,
radiation sensitivity, and tumorigenesis, we disrupted the mouse
DNA-PKcs
by homologous recombination.
DNA-PKcs
-null mice exhibit neither growth retardation
nor a high frequency of T cell lymphoma development, but show severe
immunodeficiency and radiation hypersensitivity. In contrast to the
Ku70−/−
and
Ku80−/−
phenotype,
DNA-PKcs
-null mice are blocked for V(D)J coding but not
for signal-end joint formation. Furthermore, inactivation of
DNA-PKcs
leads to hyperplasia and dysplasia of the
intestinal mucosa and production of aberrant crypt foci, suggesting a
novel role of DNA-PKcs in tumor suppression.
Induction of Ig light chain gene rearrangement in heavy chain-deficient B cells by activated Ras
Authors: Shaw Albert C. , Swat Wojciech , Davidson Laurie , Alt Frederick W.
Published: July 2002

During B cell development, rearrangement and expression of Ig heavy chain (HC) genes promote development and expansion of pre-B cells accompanied by the onset of Ig light chain (LC) variable region gene assembly. To elucidate the signaling pathways that control these events, we have tested the ability of activated Ras expression to promote B cell differentiation to the stage of LC gene rearrangement in the absence of Ig HC gene expression. For this purpose, we introduced an activated Ras expression construct into JH-deleted embryonic stem cells that lack the ability to assemble HC variable region genes and assayed differentiation potential by recombination activating gene (RAG) 2-deficient blastocyst complementation. We found that activated Ras expression induces the progression of B lineage cells beyond the developmental checkpoint ordinarily controlled by μ HC. Such Ras/JH-deleted B cells accumulate in the periphery but continue to express markers associated with precursor B cells including RAG gene products. These peripheral Ras/JH-deleted B cell populations show extensive Ig LC gene rearrangement but maintain an extent of κ LC gene rearrangement and a preference for κ over λ LC gene rearrangement similar to that of wild-type B cells. We discuss these findings in the context of potential mechanisms that may regulate Ig LC gene rearrangement.
Multiple pathways on a protein-folding energy landscape: Kinetic evidence
Authors: Goldbeck Robert A. , Thomas Yiren G. , Chen Eefei , Esquerra Raymond M. , Kliger David S.
Published: July 2002

The funnel landscape model predicts that protein folding proceeds through multiple kinetic pathways. Experimental evidence is presented for more than one such pathway in the folding dynamics of a globular protein, cytochrome
c
. After photodissociation of CO from the partially denatured ferrous protein, fast time-resolved CD spectroscopy shows a submillisecond folding process that is complete in ≈10
−6
s, concomitant with heme binding of a methionine residue. Kinetic modeling of time-resolved magnetic circular dichroism data further provides strong evidence that a 50-μs heme–histidine binding process proceeds in parallel with the faster pathway, implying that Met and His binding occur in different conformational ensembles of the protein, i.e., along respective ultrafast (microseconds) and fast (milliseconds) folding pathways. This kinetic heterogeneity appears to be intrinsic to the diffusional nature of early folding dynamics on the energy landscape, as opposed to the late-time heterogeneity associated with nonnative heme ligation and proline isomers in cytochrome
c
.
Endogenous, hyperactive Rac3 controls proliferation of breast cancer cells by a p21-activated kinase-dependent pathway
Authors: Mira Jean-Paul , Benard Valerie , Groffen John , Sanders Luraynne C. , Knaus Ulla G.
Published: July 2002

Uncontrolled cell proliferation is a major feature of cancer. Experimental cellular models have implicated some members of the Rho GTPase family in this process. However, direct evidence for active Rho GTPases in tumors or cancer cell lines has never been provided. In this paper, we show that endogenous, hyperactive Rac3 is present in highly proliferative human breast cancer-derived cell lines and tumor tissues. Rac3 activity results from both its distinct subcellular localization at the membrane and altered regulatory factors affecting the guanine nucleotide state of Rac3. Associated with active Rac3 was deregulated, persistent kinase activity of two isoforms of the Rac effector p21-activated kinase (Pak) and of c-Jun N-terminal kinase (JNK). Introducing dominant-negative Rac3 and Pak1 fragments into a breast cancer cell line revealed that active Rac3 drives Pak and JNK kinase activities by two separate pathways. Only the Rac3–Pak pathway was critical for DNA synthesis, independently of JNK. These findings identify Rac3 as a consistently active Rho GTPase in human cancer cells and suggest an important role for Rac3 and Pak in tumor growth.
Transposons and genome evolution in plants
Authors: Fedoroff Nina
Published: July 2002

Although it is known today that transposons comprise a significant fraction of the genomes of many organisms, they eluded discovery through the first half century of genetic analysis and even once discovered, their ubiquity and abundance were not recognized for some time. This genetic invisibility of transposons focuses attention on the mechanisms that control not only transposition, but illegitimate recombination. The thesis is developed that the mechanisms that control transposition are a reflection of the more general capacity of eukaryotic organisms to detect, mark, and retain duplicated DNA through repressive chromatin structures.
Stability of cytotoxic luteinizing hormone-releasing hormone conjugate (AN-152) containing doxorubicin 14-
O
-hemiglutarate in mouse and human serum
in vitro:
Implications for the design of preclinical studies
Authors: Nagy Attila , Plonowski Artur , Schally Andrew V.
Published: July 2002

Recently, we developed a series of cytotoxic peptide conjugates containing 14-
O
-glutaryl esters of doxorubicin (DOX) or 2-pyrrolino-DOX (AN-201). Serum carboxylesterase enzymes (CE) can partially hydrolyze these conjugates in the circulation, releasing the cytotoxic radical, before the targeting is complete. CE activity in serum of nude mice is about 10 times higher than in human serum. Thus, we found that the
t
1/2
of AN-152, an analog of luteinizing hormone-releasing hormone (LH-RH) containing DOX, at 0.3 mg/ml is 19.49 ± 0.74 min in mouse serum and 126.06 ± 3.03 min in human serum
in vitro
. The addition of a CE inhibitor, diisopropyl fluorophosphate (DFP), to mouse serum
in vitro
significantly (
P
< 0.01) prolongs the
t
1/2
of AN-152 to 69.63 ± 4.44 min. When DFP is used
in vivo
, 400 nmol/kg cytotoxic somatostatin analog AN-238 containing AN-201 is well tolerated by mice, whereas all animals die after the same dose without DFP. In contrast, DFP has no effect on the tolerance of AN-201. A better tolerance to AN-238 after DFP treatment is due to the selective uptake of AN-238 by somatostatin receptor-positive tissues. Our results demonstrate that the suppression of the CE activity in nude mice greatly decreases the toxicity of cytotoxic hybrids containing 2-pyrrolino-DOX 14-
O
-hemiglutarate and brings this animal model closer to the conditions that exist in humans. The use of DFP together with these peptide conjugates in nude mice permits a better understanding of their mechanism of action and improves the clinical predictability of the oncological and toxicological results.
Microglial activation precedes acute neurodegeneration in Sandhoff disease and is suppressed by bone marrow transplantation
Authors: Wada Ryuichi , Tifft Cynthia J. , Proia Richard L.
Published: July 2002

Sandhoff disease is a lysosomal storage disorder characterized by
the absence of β-hexosaminidase and storage of G
M2
ganglioside and related glycolipids in the central nervous system. The
glycolipid storage causes severe neurodegeneration through a poorly
understood pathogenic mechanism. In symptomatic Sandhoff disease mice,
apoptotic neuronal cell death was prominent in the caudal
regions of the brain. cDNA microarray analysis to monitor gene
expression during neuronal cell death revealed an upregulation of
genes related to an inflammatory process dominated by activated
microglia. Activated microglial expansion, based on gene expression and
histologic analysis, was found to precede massive neuronal death.
Extensive microglia activation also was detected in a human case of
Sandhoff disease. Bone marrow transplantation of Sandhoff disease mice
suppressed both the explosive expansion of activated microglia and the
neuronal cell death without detectable decreases in neuronal
G
M2
ganglioside storage. These results suggest a mechanism
of neurodegeneration that includes a vigorous inflammatory response as
an important component. Thus, this lysosomal storage disease has
parallels to other neurodegenerative disorders, such as Alzheimer's
and prion diseases, where inflammatory processes are believed to
participate directly in neuronal cell death.
Zic2 regulates the kinetics of neurulation
Authors: Nagai Takeharu , Aruga Jun , Minowa Osamu , Sugimoto Takashi , Ohno Yoshiki , Noda Tetsuo , Mikoshiba Katsuhiko
Published: July 2002

Mutation in human ZIC2, a zinc finger protein homologous to
Drosophila
odd-paired, causes holoprosencephaly (HPE), which is a common, severe malformation of the brain in humans. However, the pathogenesis is largely unknown. Here we show that reduced expression (knockdown) of mouse
Zic2
causes neurulation delay, resulting in HPE and spina bifida. Differentiation of the most dorsal neural plate, which gives rise to both roof plate and neural crest cells, also was delayed as indicated by the expression lag of a roof plate marker,
Wnt3a
. In addition the development of neural crest derivatives such as dorsal root ganglion was impaired. These results suggest that the
Zic2
expression level is crucial for the timing of neurulation. Because the
Zic2
knockdown mouse is the first mutant with HPE and spina bifida to survive to the perinatal period, the mouse will promote analyses of not only the neurulation but also the pathogenesis of human HPE.
Facilitated diffusion of fructose via the phosphoenolpyruvate/glucose phosphotransferase system of
Escherichia coli
Authors: Kornberg Hans L. , Lambourne Linda T. M. , Sproul Andrew A.
Published: July 2002

From mutants of
Escherichia coli
unable to utilize fructose via the phosphoenolpyruvate/glycose phosphotransferase system (PTS), further mutants were selected that grow on fructose as the sole carbon source, albeit with relatively low affinity for that hexose (
K
m
for growth ≈8 mM but with
V
max
for generation time ≈1 h 10 min); the fructose thus taken into the cells is phosphorylated to fructose 6-phosphate by ATP and a cytosolic fructo(manno)kinase (Mak). The gene effecting the translocation of fructose was identified by Hfr-mediated conjugations and by phage-mediated transduction as specifying an isoform of the membrane-spanning enzyme II
Glc
of the PTS, which we designate
ptsG
-
F
. Exconjugants that had acquired
ptsG
+
from Hfr strains used for mapping (designated
ptsG
-
I
) grew very poorly on fructose (
V
max
≈7 h 20 min), even though they were rich in Mak activity. A mutant of
E. coli
also rich in Mak but unable to grow on glucose by virtue of transposon-mediated inactivations both of
ptsG
and of the genes specifying enzyme II
Man
(
manXYZ
) was restored to growth on glucose by plasmids containing either
ptsG
-
F
or
ptsG
-
I
, but only the former restored growth on fructose. Sequence analysis showed that the difference between these two forms of
ptsG,
which was reflected also by differences in the rates at which they translocated mannose and glucose analogs such as methyl α-glucoside and 2-deoxyglucose, resided in a substitution of G in
ptsG
-
I
by T in
ptsG
-
F
in the first position of codon 12, with consequent replacement of valine by phenylalanine in the deduced amino acid sequence.
Sox6is a candidate gene forp100Hmyopathy, heart block, and sudden neonatal death
Authors: Hagiwara Nobuko , Klewer Scott E. , Samson Ricardo A. , Erickson Drew T. , Lyon Mary F. , Brilliant Murray H.
Published: July 2002

The mouseplocus encodes a gene that functions in normal pigmentation. We have characterized a radiation-induced mutant allele of the mouseplocus that is associated with a failure-to-thrive syndrome, in addition to diminished pigmentation. Mice homozygous for this mutant allele,p100H, show delayed growth and die within 2 wk after birth. We have discovered that the mutant mice develop progressive atrioventricular heart block and significant ultrastructural changes in both cardiac and skeletal muscle cells. These observations are common characteristics described in human myopathies. The karyotype ofp100Hchromosomes indicated that the mutation is associated with a chromosome 7 inversion. We demonstrate here that thep100Hchromosomal inversion disrupts both thepgene and theSox6gene. NormalSox6gene expression has been examined by Northern blot analysis and was found most abundantly expressed in skeletal muscle in adult mouse tissues, suggesting an involvement ofSox6in muscle maintenance. Thep100Hmutant is thus a useful animal model in the elucidation of myopathies at the molecular level.
NADPH oxidase is an O
2
sensor in airway chemoreceptors: Evidence from K
+
current modulation in wild-type and oxidase-deficient mice
Authors: Fu Xiao Wen , Wang Dashou , Nurse Colin A. , Dinauer Mary C. , Cutz Ernest
Published: July 2002

Pulmonary neuroepithelial bodies (NEBs) are presumed airway chemoreceptors that express the putative O
2
sensor protein NADPH oxidase and O
2
-sensitive K
+
channels K
+
(O
2
). Although there is a consensus that redox modulation of K
+
(O
2
) may be a common O
2
-sensing mechanism, the identity of the O
2
sensor and related coupling pathways are still controversial. To test whether NADPH oxidase is the O
2
sensor in NEB cells, we performed patch-clamp experiments on intact NEBs identified by neutral red staining in fresh lung slices from wild-type (WT) and oxidase-deficient (OD) mice. In OD mice, cytochrome
b
558
and oxidase function was disrupted in the gp91
phox
subunit coding region by insertion of a neomycin phosphotransferase (neo) gene. Expression in NEB cells of neo mRNA, a marker for nonfunctional gp91
phox
, was confirmed by nonisotopic
in situ
hybridization. In WT cells, hypoxia (pO
2
= 15–20 mmHg; 1 mmHg = 133 Pa) caused a reversible inhibition (≈46%) of both Ca
2+
-independent and Ca
2+
-dependent K
+
currents. In contrast, hypoxia had no effect on K
+
current in OD cells, even though both K
+
current components were expressed. Diphenylene iodonium (1 μM), an inhibitor of the oxidase, reduced K
+
current by ≈30% in WT cells but had no effect in OD cells. Hydrogen peroxide (H
2
O
2
; 0.25 mM), a reactive oxygen species generated by functional NADPH oxidase, augmented K
+
current by >30% in both WT and OD cells; further, in WT cells, H
2
O
2
restored K
+
current amplitude in the presence of diphenylene iodonium. We conclude that NADPH oxidase acts as the O
2
sensor in pulmonary airway chemoreceptors.
Convex Arrhenius plots and their interpretation
Authors: Truhlar Donald G. , Kohen Amnon
Published: July 2002

This paper draws attention to selected experiments on
enzyme-catalyzed reactions that show convex Arrhenius plots, which are
very rare, and points out that Tolman's interpretation of the
activation energy places a fundamental model-independent constraint on
any detailed explanation of these reactions. The analysis presented
here shows that in such systems, the rate coefficient as a function of
energy is not just increasing more slowly than expected, it is actually
decreasing. This interpretation of the data provides a constraint on
proposed microscopic models, i.e., it requires that any successful
model of a reaction with a convex Arrhenius plot should be consistent
with the microcanonical rate coefficient being a decreasing function of
energy. The implications and limitations of this analysis to
interpreting enzyme mechanisms are discussed. This model-independent
conclusion has broad applicability to all fields of kinetics, and we
also draw attention to an analogy with diffusion in metastable fluids
and glasses.
The Effect of Noise on Memory for Spoken Syllables
Authors: Surprenant Aimée M.
Published: July 2002

Two experiments explore the effects of noise on memory for spoken syllables. Participants identified and then recalled nonsense syllables under different levels of noise. There were significant decrements in memory, even in conditions where there was no effect of the noise on identification of the syllable. The experiments showed effects over all list positions as well as decreases in the final, or recency, portion of the curve. Results suggest that both capacity and dual‐coding play a role in immediate memory.
A Study of Class Size Effects in English School Reception Year Classes
Authors: Blatchford Peter , Goldstein Harvey , Martin Clare , Browne William
Published: July 2002

Abstract This article reviews the existing evidence on the relationship between class size and achievement for children in their first years of schooling. It then describes a large‐scale longitudinal study of such children within English Local Education Authorities and presents results for achievement progress in literacy and mathematics during the reception year. Using a series of multilevel models, it is shown that there is a relationship with size of class, after various confounding factors have been allowed for, and that there are interactions between class size and initial achievement and between class size and entitlement to free school meals. It is argued that these results, especially the differential effects for different groups of children, could have important implications for educational policy.
Visual filtering and covert orienting in persons with Down syndrome
Authors: Randolph Beth , Burack Jacob A.
Published: July 2002

A forced-choice reaction time (RT) task was used to examine the efficiency of visual filtering (the inhibition of processing of irrelevant stimuli) and covert orienting (shifts of visual attention independent of eye movement) components of attention in persons with Down syndrome ( n = 20) and children of average intelligence ( n = 20) matched for mental age (MA) (average MA = approximately 5.4 years). Conditions varied with regard to presence or absence of distractors, and the validity (valid, invalid, or neutral) of location cues. Contrary to expectations, persons with Down syndrome and MA-matched children of average intelligence at approximately age 5 showed similar patterns of performance on a task that required filtering distracting stimuli and searching for relevant information in the visual field. Both groups responded more efficiently to a target preceded by a valid cue as compared to a target preceded by an invalid or neutral cue. In addition, performance was more efficient with a target that was presented without irrelevant information as compared to one that was flanked on either side by extraneous, nontarget information and therefore necessitated filtering for efficient performance. These two findings indicate that: (1) disengaging from the location of an incorrect cue, and then searching for, locating, and responding to a target requires more time and attention than simply locating and responding to a target that has been validly cued; and (2) processing and responding to a target flanked by extraneous information entails filtering, and therefore requires more time and resources than simply responding to a target without distractors. In general, the development of visual reflexive, covert orienting, and filtering are intact in persons with Down syndrome relative to their level of functioning at an MA level of approximately 5 years, a period that is critical in the development of attentional processes.
School Work, Teachers, and Peers: The World of First Grade
Authors: Donelan-McCall Nancy , Dunn Judy
Published: July 2002

Children’s perceptions of their experiences with their school work, and teacher and peer relationships were studied in 44 second-born children, participating with their mothers and siblings in a longitudinal investigation, who were interviewed in October and May of their first-grade year. Overall, the majority of children were very positive about their experiences in all three areas of school adjustment. Modest associations between children’s perceptions of their school work, teacher, and peer experiences suggest that although most children perceived their experiences as positive (or negative) across all three areas, some children reported difficulties in one or two individual areas. In addition, although many children’s reported school experiences remained stable over the year, some children’s perceptions changed. The majority of children whose perceived school experiences were marked by discontinuity over the year were positive at the beginning of the year but relatively negative at the end. Finally, the findings from this investigation draw attention to some of the antecedent variables related to children’s subsequent school experiences, in particular, their emotion understanding and earlier relationships with their older siblings.
Alpha-Glutathione S-Transferase in the Assessment of Hepatotoxicity—Its Diagnostic Utility in Comparison with Other Recognized Markers in the Wistar Han Rat
Authors: Giffen Paul S. , Pick Chris R. , Price Mark A. , Williams Ann , York Malcolm J.
Published: July 2002

The diagnostic utility of alpha-glutathione S-transferase ( αGST) in the assessment of acute hepatotoxicity was compared with a range of markers including alanine aminotransferas e (ALT) and aspartate aminotransferas e (AST). Rats were given a single oral dose of either α-naphthylisothiocynate (ANIT), bromobenzen e (BrB), or thioacetamide (TAM) at concentrations previously shown to induce marked hepatotoxicity. The progression of each hepatic lesion was monitored by the measurement of a battery of markers, including αGST, in plasma collected at time points ranging from 3 h to 7 days after dosing. αGST was seen to increase significantly at 24 h (ANIT/BrB) and 3 h (TAM) postdosing, corresponding with histopathological findings. For each compound, when the degree of insult was most severe, fold increases in αGST were greater than those seen with ALT and AST, yet lower than those seen with glutamate dehydrogenas e (BrB and ANIT), sorbitol dehydrogenas e (TAM), or total bilirubin and bile acids (ANIT). Elevations in α GST were also detected no earlier than any other marker. αGST in the rat was shown to be a valid marker of hepatotoxicity ; however, its measurement offered no additional information in detecting either the time of onset/recovery or the severity of each type of hepatic injury induced.
The Digital Divide and ICT Learning in Rural Communities: Examples of Good Practice Service Delivery
Authors: Huggins Robert , Izushi Hiro
Published: July 2002

This article aims to gain a greater understanding of relevant and successful methods of stimulating an ICT culture and skills development in rural areas. The paper distils good practice activities, utilizing criteria derived from a review of the rural dimensions of ICT learning, from a range of relevant initiatives and programmes. These good practice activities cover: community resource centres providing opportunities for ‘tasting’ ICTs; video games and Internet Cafés as tools removing ‘entry barriers’; emphasis on ‘user management’ as a means of creating ownership; service delivery beyond fixed locations; use of ICT capacities in the delivery of general services; and selected use of financial support.
(1→3)‐β‐D‐glucanemia in deep mycosis
Authors: Obayashi Taminori
Published: July 2002

Factor G, a coagulation proenzyme of the Japanese horseshoe crab (Tachypleus tridentatus), is extremely sensitive to (1→3)‐β‐D‐glucan, which is a characteristic cell‐wall constituent of fungi. Using this factor and by a digestion study with (1→3)‐β‐D‐glucan, we showed that blood from patients with deep m ycosis contains the glucan. It was detected in 39 out of 41 fungal febrile episodes (sensitivity 90%), but in none of the 59 nonfungal febrile episodes (specificity 100%).
Genetics of Alcoholism: A Review of Recent Studies in Human and Animal Models
Authors: Foroud Tatiana , Li Ting‐Kai
Published: July 2002

There is substantial evidence for a significant genetic component to the risk of alcoholism. In searching for genes that contribute to this risk, several approaches may be utilized in order to identify the genetic loci underlying alcoholism susceptibility. Several candidate genes have been evaluated for their role in alcoholism; however, with the exception of the enzymes of alcohol metabolism, results from these studies have been inconsistent. Recently, two large studies have employed a genome screen methodology to identify novel genes contributing to the risk of alcoholism. As an alternative strategy, researchers have utilized mouse and rat models to identify quantitative trait loci influencing alcohol preference. Through the development of congenic lines and transgenic and knock‐out animals, candidate genes can be identified and evaluated for their role in alcohol preference.
Biological Monitoring of Exposure to Cisplatin in Rats Using SOS Chromotest
Authors: Lee Sang-Jun , Hur Jang-Hyun , Lee Byung-Hoon
Published: July 2002

Cisplatin (CDDP) is a potent antitumor drug used in the treatment of a variety of solid tumors. The purpose of the present study was to establish screening biomarker of exposure to CDDP using SOS chromotest. The ultimate goal of this screen is to facilitate the choice of an effective drug and the prognosis of the therapy. In the current screening protocol, the SOS chromotests were performed on the urine of Sprague-Dawley rats administered intravenously with CDDP. Urine samples were collected individually in the metabolic cage at 6 (U0–6) and 12 hours (U6–12) after treatment and were tested their DNA damaging effects. The urine samples obtained from the rats administered with 1 mg/kg CDDP did not induce SOS response in our experimental conditions. At a dose of 5 mg/kg, two out of five rat showed more than 50% increase in the DNA damaging effect compared to that of the control. The genotoxic effect was observed only in the U0–6, whereas the U6–12 were not genotoxic but cytotoxic to the test strain. Similar results were obtained at a dose of 10 mg/kg: 5 out of 10 rats showed SOS response and the U6–12 were also proven to be cytotoxic. These results suggest that the method presented in this study could be used as a biomarker of exposure to CDDP.
Subchronic Toxicity Study of 1,3-Propanediol Administered Orally to Rats
Authors: Gingell Ralph , Kirkpatrick Jeannie B. , Steup David R.
Published: July 2002

1,3-Propanediol was a specialty chemical that, due to a novel manufacturing process, is now commercially available in large quantities. Its subchronic toxicity has been evaluated in rats, with special emphasis on potential male reproductive effects. 1,3-Propanediol in deionized water was administered orally by gavage to three groups of 10 male and 10 female Crl:CD(SD)BR rats for a period of 90 consecutive days. Dosage levels were 100, 300, and 1000 mg/kg/day, and a control group received water at a constant volume of 10 ml/kg/day. All animals survived to the scheduled necropsy, and there were no effects on the clinical condition of the animals, body weights, body weight gains, food consumption or organ weights. There were no effects on hematology or serum chemistry parameters. Spermatogenic endpoints were unaffected in all treated males. No treatment-related changes were observed on macroscopic or microscopic examinations of selected organs. Under the conditions of the study, the no-observed-effect level (NOEL) for systemic toxicity of 1,3-propanediol administered orally via gavage to male and female rats for 90 consecutive days was 1000 mg/kg/day, the highest dose tested.
The Relevance of Photomutagenicity Testing as a Predictor of Photocarcinogenicity
Authors: Müller Lutz , Kasper Peter
Published: July 2002

Today's lifestyle is associated with frequent and intense exposure to ultraviolet radiation (UVR). The tumorigenic effects of UVR are well known. Specifically, the premutagenic lesions of UVB (290-320 nm) are known to be the most important molecular events in UVR tumorigenicity. The less carcinogenic UVA (320-400 nm) mainly generates oxidative damage in the DNA via photody-namic generation of active oxygen species involving endogenous or exogenous photosen sitizers. Several pharmaceuticals are known to act as photosensitizers. Photoinstable phenothiazines, furocoumarins, and fluoroquinolones were shown to be very efficient inducers of chromosomal damage in mammalian cells in culture. Photocar cinogenicity testing in hairless mice of furocoumarins and several fluoroquinolones demonstrated a higher incidence and a shorter latent period for skin tumors compared to UVR alone. These data show a good correlation between the photomutagenic and photocarcinogenic potential of these compounds. Although mammalian cells possess effective repair mechanisms for oxidative damage, photoproducts, and dimers, these repair mechanisms can be overloaded. Eventually, unrepaired damage leads to gene mutations or chromosomal damage in exposed cells and to tumors in the skin. Therefore, in vitro photomutageni-city testing in mammalian cells may be an early and easy-to-measure predictor of the photocarcinogenic potential of a pharmaceutical.
Alcohol‐related diarrhea
Authors: Chiba Toshimi , Phillips Sidney F.
Published: July 2002

Alcohol generates a large caloric yield without supplying any essential nutrients; alcoholics may thus maintain body weight while suffering from malnutrition. In addition, diarrhea is a common complaint of both acute and chronic alcoholics. Here, we review the effects of alcohol on gastrointestinal morphology, function, its nervous system and motility. Acute morphological changes such as erosions, inflammatory cell infiltrations and microvascular changes are seen in the stomach and small intestine in acute alcoholics. In addition, atrophic gastritis, reduced villous height and decreased mucosal surface area of the small intestine have been described in chronic alcoholics. Acute administration of alcohol inhibits absorption of nutrients and fluids, and can stimulate secretion of water and electrolytes. Bacterial overgrowth in the proximal small intestine and decreased pancreatic secretions have been also described in chronic alcoholics. The well‐known deleterious effects of alcohol on the central nervous system raise the possibility of similar acute and chronic effects of the enteric nervous system. Such effects could alter motility and transit. Indeed, esophageal dysmotility and delayed gastric emptying have been observed with high concentrations of alcohol in experimental studies and in chronic alcoholics. Small bowel motility and transit may be abnormal in both acute and chronic alcoholics, and colonic propulsive motility is increased after acute administration of alcohol. Any, or all, of these changes in gastrointestinal functions may contribute to diarrhea in acute binge drinkers and chronic alcoholics. Unfortunately, there is a lack of systematic studies of the pathophysiology of alcohol abuse, and an integrating concept of the diarrhea of alcoholics is still not possible.
Soft Tissue Sarcoma of the Hand or Foot: Conservative Surgery andRadiotherapy
Authors: Jyothirmayi Rema , Sittampalam Yoga , Harmer Clive
Published: July 2002

Purpose. Conservative treatment in the form of limited surgery and post‐operative
radiotherapy is controversial in hand and foot sarcomas, both due to poor radiation
tolerance of the palm and sole, and due to technical difficulties in achieving adequate
margins.This paper describes the local control and survival of 41 patients with soft tissue
sarcoma of the hand or foot treated with conservative surgery and radiotherapy.
The acute and late toxicity of megavoltage radiotherapy to the hand and foot are described.
The technical issues and details of treatment delivery are discussed.
The factors influencing local control after radiotherapy are analysed.

Subjects . Eighteen patients had sarcomas of the hand and 23 of the foot.
All patients received post‐operative radiotherapy, the majority receiving a dose of 60
Gy in 2‐Gy daily fractions using a two‐phase treatment.

Results . The acute and late toxicity of treatment were within acceptable limits.
The actuarial 5‐year overall survival of the whole patient group was 67.6% and the
local relapse‐free survival was 44%.The local control was similar in tumours of hand
and foot, and in patients treated at first presentation or relapse.

Discussion. Post‐operative radiotherapy to the hand or foot appears to be a well
tolerated treatment resulting in long‐term local control in a significant proportion of patients.
The increased frequency of recurrence within the high‐dose volume
suggests the need for the use of higher total doses of radiotherapy.