Beginning readers' use of orthographic analogies in word reading

This research re-investigated the claim that beginning readers exploit information from the orthographic rime of clue words to help them to decode unfamiliar words. In Experiment 1, first-grade children were equally able to use orthographic information from the beginning, middle, and end of clue words to identify unfamiliar target words. Moreover, the improvement in reading end-(or orthographic rime-) same target words following clue word presentation reflected phonological priming. In second-grade children, with correction for retesting effects, improvement following clue word presentation for end-same and beginning-same target words was equivalent, although end-same target words improved more than middle-same target words. In Experiment 2, both first- and second-grade children were able to use orthographic information from the beginning, middle, and end of clue words to identify unfamiliar words. Clue word presentation enhanced the reading of beginning-same and end-same target words more than middle-same target words. Improvement was the same for beginning-same and end-same target words. Target word improvement following clue word presentation was greater than that for phonologically primed words only in children reading target words sharing the beginning sequence of the clue word.

Increased risk of lung cancer among different types of professional drivers in Denmark

OBJECTIVES

To study risk of lung cancer among groups of professional drivers probably exposed to different levels of traffic exhaust fumes.

METHODS

A nationwide case-control study (1970-89) based on employees comprising 28,744 men with primary lung cancer and incidence density sampled matched controls (1:1). Employment histories were reconstructed back to 1964 for each study subject from the records of a nationwide pension scheme with compulsory membership. Socioeconomic status was derived from the individual job title taken from the national population registry. Information on tobacco smoking habits was available from historical surveys. Relative risks were estimated by odds ratios (ORs) based on conditional logistic regression analyses.

RESULTS

In total 2251 of the male lung cancer cases had been employed as bus, lorry, taxi, or unspecified drivers. No significant difference in tobacco smoking habits was found among professional male Danish drivers and the total employed population. The OR for lung cancer adjusted for socioeconomic status was 1.6 (95% confidence interval (95% CI) 1.2 to 2.2) among taxi drivers, who were considered to be exposed to the highest concentrations of vehicle exhaust fumes, and 1.3 (1.2 to 1.5) for bus and lorry drivers. The OR was 1.4 (1.3 to 1.5) for unspecified drivers. The adjusted risk of lung cancer increased significantly with increasing duration of employment as a driver, and the risk was highest for long term taxi drivers with 10 years of lag time (OR 3.0; 1.2 to 6.8).

CONCLUSION

Occupational factors, probably exposure to vehicle exhaust, seems to play an important part in the development of lung cancer among drivers.

Morbidity in Turner syndrome

Turner syndrome afflicts approximately 50 per 100,000 females and is characterized by retarded growth, gonadal dysgenesis, and infertility. Much attention has been focused on growth and growth promoting therapies, while less is known about the natural course of the syndrome, especially in adulthood. We undertook this study to assess the incidence of diseases relevant in the study of Turner syndrome. The study period was from January 1, 1984 to December 31, 1993, and the study base was all women living in Denmark during the study period. We used data from the Danish Cytogenetic Central Register and the Danish National Registry of Patients to assess morbidity. This study supports several earlier studies reporting increased morbidity and confirms results of a recent study on cancer in Turner syndrome. Women with Turner syndrome seem to have an increased incidence of fractures, osteoporotic fractures in adulthood, and non-osteoporotic fractures in childhood. Furthermore, diabetes mellitus, both NIDDM and IDDM, was found with a markedly increased incidence in Turner syndrome, as well as ischemic heart disease, hypertension, and stroke. The risk of cancer, except cancer of the large bowel, does not seem to be elevated in Turner syndrome. Our data suggest that patients with Turner syndrome are extraordinarily prone to abnormalities constituting the metabolic syndrome (e.g., hypertension, dyslipidaemia, NIDDM, obesity, hyperinsulinemia and hyperuricemia). The present data may help to explain the decreased life span found in patients with Turner syndrome.

Vitamin A and cancer prevention I: observations in workers previously exposed to asbestos at Wittenoom, Western Australia

Our aim was to describe a vitamin A-based cancer prevention program for former asbestos workers and to check for possible harmful effects by comparing rates of disease and death in study subjects with subjects who chose not to join. All subjects had been occupationally exposed to crocidolite at Wittenoom Gorge between 1943 and 1966; 1,677 subjects indicated interest in the program and 1,203 joined between June 1990 and May 1995. Comparison subjects consisted of 996 former workers known to be alive in Western Australia in 1990 who did not join the program. Program subjects were provided with annual supplies of vitamin A (either synthetic beta-carotene or retinol), help in quitting smoking and dietary advice. The comparison group received only mail contact. Both groups were followed up to December 1994 for vital status and cancer information, and rates of cancer and death from various causes were compared. Mortality in both groups was higher than expected (standardised mortality ratio 1.23 in program subjects and 1.67 in comparison subjects). After adjustment for age, smoking and asbestos exposure, the relative rates in participants compared with non-participants was below I for all examined cancers and causes of death. For mesothelioma and lung cancer, group differences increased with time from entry, whereas other differences dissipated with time. No significant side effects were reported. In conclusion, program participants had significantly lower mortality than non-participants, but the rates of the 2 groups converged with time.

Vitamin A and cancer prevention II: comparison of the effects of retinol and beta-carotene

Former blue asbestos workers known to be at high risk of asbestos-related diseases, particularly malignant mesothelioma and lung cancer, were enrolled in a chemo-prevention program using vitamin A. Our aims were to compare rates of disease and death in subjects randomly assigned to beta-carotene or retinol. Subjects were assigned randomly to take 30 mg/day beta-carotene (512 subjects) or 25,000 IU/day retinol (512 subjects) and followed up through death and cancer registries from the start of the study in June 1990 till May 1995. Comparison between groups was by Cox regression in both intention-to-treat analyses and efficacy analyses based on treatment actually taken. Median follow-up time was 232 weeks. Four cases of lung cancer and 3 cases of mesothelioma were observed in subjects randomised to retinol and 6 cases of lung cancer and 12 cases of mesothelioma in subjects randomised to beta-carotene. The relative rate of mesothelioma (the most common single cause of death in our study) for those on retinol compared with those on beta-carotene was 0.24 (95% CI 0.07-0.86). In the retinol group, there was also a significantly lower rate for death from all causes but a higher rate of ischaemic heart disease mortality. Similar results were found with efficacy analyses. Our results confirm other findings of a lack of any benefit from administration of large doses of synthetic beta-carotene. The finding of significantly lower rates of mesothelioma among subjects assigned to retinol requires further investigation.

Environmental exposure to crocidolite and mesothelioma: exposure-response relationships

This study aimed to estimate exposure-response relationships for mesothelioma and environmental exposure to crocidolite. All 4,659 former residents of Wittenoom, Western Australia (WA) who lived there between 1943 and 1993 for at least 1 mo and were not directly employed in the crocidolite industry, were followed-up through the WA death, cancer and mesothelioma registries, electoral rolls, and telephone books. In 1992, all subjects who should be traced were sent a questionnaire. Exposure levels were estimated from results of periodic environmental surveys and duration of residence. Incidence rates were standardized to the World Population and Cox Regression was used to estimate the effects of exposure on incidence. To the end of 1993, 27 cases of mesothelioma were diagnosed. Mesothelioma cases stayed longer at Wittenoom, had a higher average intensity of exposure, and a higher cumulative exposure to crocidolite than control subjects. The standardized incidence of mesothelioma was 260 per million person-years, and was similar for males and females. The rate increased significantly with time from first exposure, duration of exposure and cumulative exposure. At these levels of crocidolite exposure, there is a significantly increased risk of mesothelioma, which is dose-dependent.

Protein distance constraints predicted by neural networks and probability density functions

We predict interatomic Calpha distances by two independent data driven methods. The first method uses statistically derived probability distributions of the pairwise distance between two amino acids, whilst the latter method consists of a neural network prediction approach equipped with windows taking the context of the two residues into account. These two methods are used to predict whether distances in independent test sets were above or below given thresholds. We investigate which distance thresholds produce the most information-rich constraints and, in turn, the optimal performance of the two methods. The predictions are based on a data set derived using a new threshold which defines when sequence similarity implies structural similarity. We show that distances in proteins are predicted more accurately by neural networks than by probability density functions. We show that the accuracy of the predictions can be further increased by using sequence profiles. A threading method based on the predicted distances is presented. A homepage with software, predictions and data related to this paper is available at http://www.cbs.dtu.dk/services/CPHmodels/.

Comparison of information on occupation and lifestyle habits obtained from European man-made vitreous fibre production workers and their relatives

BACKGROUND

Studies of the aetiology of fatal diseases often rely on data obtained from relatives, which can cause loss of precision and introduce bias. We assessed the quality of such information on demographics, occupation, smoking and alcohol habits.

METHODS

We compared contemporary interviews, based on a structured questionnaire, with male workers from the man-made vitreous fibre production industry in four European countries and their relatives. The participation rate was 63% (74 pairs of workers and relatives).

RESULTS

Only minor differences in the ability to answer the questions appeared among workers and relatives, except for specific occupational questions. There was moderate to excellent agreement for demographics, residential and work history (kappa or intraclass correlation range: 0.44-0.98). For smoking habits, beer and wine consumption the agreement was good to excellent (range: 0.59-0.99). In particular, number of different residential areas, jobs, industries, and duration of wine drinking were significantly underreported by the relatives. No general determinant for reduced agreement appeared.

CONCLUSIONS

In general, the quality of information obtained from relatives appeared good. However, information on specific occupational exposures may be improved by supplementing the information from relatives with details obtained from colleagues, occupational hygiene experts or occupation-exposure matrices.

Expression of the H2-E molecule mediates protection to collagen-induced arthritis in HLA-DQ8 transgenic mice: role of cytokines

Transgenic mice expressing DQA1*0301 and DQB1*0302 (HLA-DQ8) molecules in class II-deficient Ab degree mice are susceptible to collagen-induced arthritis (CIA). To evaluate the role of the H2-E molecule (a homolog of HLA-DR) in DQ-restricted arthritis, the H2-E gene was introduced into DQ8.Ab degree mice to generate DQ8/E+.Ab degree mice. Expression of the E molecule protects DQ8.Ab degree mice against arthritis. In vitro studies using draining lymph nodes from mice primed with bovine type II collagen (BII) showed that the response to BII in both transgenics is DQ and CD4 restricted. Challenge with BII in vitro leads to production of high levels of IFN-gamma in DQ8 and IL-4 in DQ8/E+ mice. We have hypothesized that the H2-E molecule modulates the T cell repertoire and changes the cytokine balance, resulting in protection of disease.

Expression of natural and synthetic genes encoding herpes simplex virus 1 protease in Escherichia coli and purification of the protein

An attractive target for anti-herpes chemotherapy is the herpes simplex virus 1 (HSV-1) protease encoded by the UL26 gene. Studies with HSV-1 strains that harbour mutations in the protease gene have demonstrated that the protease is essential for DNA packaging and virus maturation. The UL26 translation product is 635 amino acids long and undergoes autoproteolytic processing between residues Ala247/Ser248 and Ala610/Ser611. The N-terminal processing product (amino acids 1-247) contains the protease domain. To perform crystallization studies and high throughput screening for potent inhibitors, large amounts of the HSV-1 protease are required. However, expression of the natural HSV-1 protease gene in Escherichia coli using a T7-promoter-regulated system is low and does not allow for the efficient production of larger amounts of highly purified enzyme. In this report, we describe the use of a synthetic protease gene with optimized E. coli codon usage. The level of protease expression was at least 20 times higher with the synthetic gene as compared to the natural UL26 gene. The HSV-1 protease was purified to homogeneity in three steps using mixed-bed ion-exchange chromatography, affinity chromatography, and hydroxyapatite chromatography.

Evaluation of pretransplant donor anti-recipient cytotoxic and helper T lymphocyte responses as correlates of acute graft-vs.-host disease and survival after unrelated marrow transplantation

We analyzed pretransplant donor anti-recipient cytotoxic and helper T lymphocyte (CTL and HTL) responses separately in two cohorts of unrelated marrow transplant recipients. Donors and recipients were typed for HLA-A and -B antigens by serologic methods, and for HLA-DRB1 by molecular methods. A single mismatch for a cross-reactive HLA-A or -B antigen or the -DRB1 allele was accepted in patients younger than 36 years if an HLA-A, -B, or -DRB1-matched donor could not be identified. The combination of methotrexate and cyclosporine was used for graft-vs.-host disease (GVHD) prophylaxis, and marrows were not T cell depleted. Donor anti-recipient CTL precursor frequencies showed no correlation with the severity of acute GVHD or with survival after transplantation. HTL responses were detected in the presence of HLA-class II disparity and showed weak correlations with the severity of acute GVHD (p = 0.054) and with survival after transplantation (p = 0.08). These results suggest that testing donor anti-recipient CTL responses before unmodified marrow transplantation does not predict clinically important events and is not likely to help select unrelated donors. With the current availability of molecular genetic methods for assessing HLA-class II compatibility, testing donor anti-recipient HTL responses is not likely to add information that would help select unrelated donors.

Spectrin properties and the elasticity of the red blood cell membrane skeleton

Two models of spectrin elasticity are developed and compared to experimental measurements of the red blood cell (RBC) membrane shear modulus through the use of an elastic finite element model of the RBC membrane skeleton. The two molecular models of spectrin are: (i) An entropic spring model of spectrin as a flexible chain. This is a model proposed by several previous authors. (ii) An elastic model of a helical coiled-coil which expands by increasing helical pitch. In previous papers, we have computed the relationship between the stiffness of a single spectrin molecule (K) and the shear modulus of a network (mu), and have shown that this behavior is strongly dependent upon network topology. For realistic network models of the RBC membrane skeleton, we equate mu to micropipette measurements of RBCs and predict K for spectrin that is consistent with the coiled-coli molecular model. The value of spectrin stiffness derived from the entropic molecular model would need to be at least 30 times greater to match the experimental results. Thus, the conclusion of this study is that a helical coiled-coil model for spectrin is more realistic than a purely entropic model.

The sympathetic nervous system is involved in the maintenance but not initiation of the hypertension induced by N(omega)-nitro-L-arginine methyl ester

Studies in anesthetized animals have advanced the theory that there is an important neurogenic component to the hypertension caused by pharmacological inhibition of nitric oxide, but studies in conscious animals have produced conflicting evidence for and against this theory. To try to reconcile the seemingly contradictory data, we hypothesized that the neurogenic component of this hypertension is time dependent such that the sympathetic nervous system is involved primarily in the maintenance, rather than the initiation, of the hypertension. We measured intra-arterial pressure in conscious, unrestrained rats with and without guanethidine-induced sympathectomy during varying durations of intravenous N(omega)-nitro-L-arginine methyl ester (L-NAME). The major new finding is that sympathectomy had no effect on the hypertensive response to bolus injections of L-NAME but in the same rats it produced a greater than 50% attenuation in the hypertension seen after 6 days of continuous L-NAME (change in mean arterial pressure, 23+/-4 versus 55+/-4 mm Hg, P<.01, sympathectomy versus control). Using 8-hour infusions of L-NAME, we found that 60 minutes was the minimum time required for detecting a sympathectomy-sensitive component of L-NAME-induced hypertension. Furthermore, we demonstrate that the magnitude of this component increases further between 8 hours to 6 days of continuous L-NAME: it accounted for only 18% of the total hypertensive response at 8 hours but 61% after 6 days. From these experiments, we conclude that the importance of the sympathetic system in the pathogenesis of L-NAME-induced hypertension accrues slowly over hours and days, and thus its importance can be overlooked by focusing on the initial phase of the hypertension.

Determination of acetyl-CoA enrichment in rat heart and skeletal muscle by 1H nuclear magnetic resonance analysis of glutamate in tissue extracts

The contribution of a 13C-enriched substrate to the acetyl-CoA pool in animal tissues is typically measured by analysis of glutamate enrichment from tissue extracts. 13C NMR analysis offers the advantages of minimal sample processing and high information content, but has a low analytical sensitivity compared to other methods of tracer analysis such as GC/MS. We present a sensitive, simple, and direct 1H NMR measurement of glutamate C4 enrichment from tissue extracts. The method is demonstrated with heart and hindlimb muscle tissue extracts of rats infused with [2,4,6,8-13C4]-octanoate, a source of [2-13C]acetyl-CoA. Glutamate C4 enrichment in extracts of individual hindlimb soleus muscles weighing approximately 150 mg and containing approximately 0.3 mumol of glutamate was quantified by 1H NMR within about 40 min. Glutamate C4 enrichment measurements by 1H NMR in heart and gastrocnemius muscle were also highly correlated with independent measurements obtained from 13C NMR isotopomer analysis.

Relation between phylogeny of African green monkey CD4 genes and their respective simian immunodeficiency virus genes

An apparent species-specific relatedness of SIVagm suggests a coevolution with their natural hosts. However, the exact species or subspecies classification of African green monkeys, AGM, is uncertain because current classification schemes rely on phenotype markers, while more definitive genetic data are lacking. In this study, the CD4 protein involved in tissue type recognition was genetically cloned and sequenced from PBMC RNA from all AGM species, including Barbados green monkeys (BGM). Phylogenetic trees were constructed that also included genomic CD4 nucleotide sequences from patas, sooty mangabeys, rhesus and pig-tail macaques, chimpanzees, and humans. Chimpanzees and humans consistently clustered together. Monkeys within the Cercopithecus genus formed a separate cluster which included pata monkeys, supporting its grouping as a member of Cercopithecus. Surprisingly, sooty mangabeys were genetically more closely related to Asian macaques than to other African species, which might explain why macaques are more susceptible to infection by the SIVsm group than to infection by SIVagm or HIV-1 and why patas, on the other hand, are highly susceptible to SIVagm infection. Based on CD4 genetic data, tantalus, vervets, grivets, and sabaeus formed separate subgroups with BGM grouping closely with vervets. The branching order of the AGM species was related to that of their respective SIVagm env sequences. The study suggests a strong correlation between CD4 phylogeny and the susceptibility of the host species to infection by a specific lentivirus and supports the assumption of a coevolution of SIVagm and AGM. CD4 sequencing is suggested as a relevant method for genetic determination of primate species.

ATP-sensitive potassium channels mediate contraction-induced attenuation of sympathetic vasoconstriction in rat skeletal muscle

Sympathetic vasoconstriction is sensitive to inhibition by metabolic events in contracting rat and human skeletal muscle, but the underlying cellular mechanisms are unknown. In rats, this inhibition involves mainly alpha2-adrenergic vasoconstriction, which relies heavily on Ca2+ influx through voltage-dependent Ca2+ channels. We therefore hypothesized that contraction-induced inhibition of sympathetic vasoconstriction is mediated by ATP-sensitive potassium (KATP) channels, a hyperpolarizing vasodilator mechanism that could be activated by some metabolic product(s) of skeletal muscle contraction. We tested this hypothesis in anesthetized rats by measuring femoral artery blood flow responses to lumbar sympathetic nerve stimulation or intraarterial hindlimb infusion of the specific alpha2-adrenergic agonist UK 14,304 during KATP channel activation with diazoxide in resting hindlimb and during KATP channel block with glibenclamide in contracting hindlimb. The major new findings are twofold. First, like muscle contraction, pharmacologic activation of KATP channels with diazoxide in resting hindlimb dose dependently attenuated the vasoconstrictor responses to either sympathetic nerve stimulation or intraarterial UK 14,304. Second, the large contraction-induced attenuation in sympathetic vasoconstriction elicited by nerve stimulation or UK 14,304 was partially reversed when the physiologic activation of KATP channels produced by muscle contraction was prevented with glibenclamide. We conclude that contraction-induced activation of KATP channels is a major mechanism underlying metabolic inhibition of sympathetic vasoconstriction in exercising skeletal muscle.

[Prenatal and postnatal prevalence of Turner syndrome. A registry-based study]

The prevalence of Turner's syndrome in Denmark 1970-1993 was studied and the validity of prenatal diagnosis was assessed. The study was conducted on prenatal and postnatal Turner's syndrome in the Danish Cytogenetic Central Register. All registered Turner's syndrome karyotypes (100 prenatal cases and 215 postnatal cases) at the Danish Cytogenetic Central Register were included. The main outcome measures were prevalence of Turner's syndrome karyotypes among prenatally tested fetuses and Turner's syndrome among liveborn infants. The results showed that among infant girls, prevalence of Turner's syndrome was 32/100,000. Among female fetuses tested by amniocentesis, prevalence of Turner's syndrome karyotypes was 176/100,000 (relative risk of syndrome, 6.74 compared with prevalence among untested pregnancies). Among female fetuses tested by chorion villus sampling, prevalence of syndrome karyotypes was 392/100,000 (relative risk, 16.8). We excluded prenatal tests referred because of results of ultrasound scanning: among fetuses tested by amniocentesis revised relative risk was 5.68, while revised relative risk among fetuses tested by chorion villus sampling was 13.3. For 29 fetuses with prenatal diagnosis of possible Turner's syndrome, pregnancy was allowed to continue and 24 of the children were live born. Thirteen of the liveborn children were karyotyped postnatally, and the diagnosis of Turner's syndrome had to be revised for eight, seven being normal girls and one boy. This gives a tentative predictive value of amniocentesis in the diagnosis of Turner's syndrome between 21% and 67%. There was no significant relation between mother's age and risk of Turner's syndrome. In conclusion, a discrepancy between prenatal and postnatal prevalence of Turner's syndrome challenges the specificity of prenatal examination in diagnosing Turner's syndrome.

Cancer mortality among man-made vitreous fiber production workers

We have updated the follow-up of cancer mortality for a cohort study of man-made vitreous fiber production workers from Denmark, Finland, Norway, Sweden, United Kingdom, Germany, and Italy, from 1982 to 1990. In the mortality analysis, 22,002 production workers contributed 489,551 person-years, during which there were 4,521 deaths. Workers with less than 1 year of employment had an increased mortality [standardized mortality ratio (SMR) = 1.45; 95% confidence interval (CI) = 1.37-1.53]. Workers with 1 year or more of employment, contributing 65% of person-years, had an SMR of 1.05 (95% CI = 1.02-1.09). The SMR for lung cancer was 1.34 (95% CI = 1.08-1.63, 97 deaths) among rock/slag wool workers and 1.27 (95% CI = 1.07-1.50, 140 deaths) among glass wool workers. In the latter group, no increase was present when local mortality rates were used. Among rock/slag wool workers, the risk of lung cancer increased with time-since-first-employment and duration of employment. The trend in lung cancer mortality according to technologic phase at first employment was less marked than in the previous follow-up. We obtained similar results from a Poisson regression analysis limited to rock/slag wool workers. Five deaths from pleural mesothelioma were reported, which may not represent an excess. There was no apparent excess for other categories of neoplasm. Tobacco smoking and other factors linked to social class, as well as exposures in other industries, appear unlikely to explain the whole increase in lung cancer mortality among rock/slag wool workers. Limited data on other agents do not indicate an important role of asbestos, slag, or bitumen. These results are not sufficient to conclude that the increased lung cancer risk is the result of exposure to rock/slag wool; however, insofar as respirable fibers were an important component of the ambient pollution of the working environment, they may have contributed to the increased risk.

Temperature-sensitive mutants of Corynebacterium ammoniagenes ATCC 6872 with a defective large subunit of the manganese-containing ribonucleotide reductase

Chemical mutagenesis of the nucleotide-producing strain Corynebacterium ammoniagenes ATCC 6872 with N-methyl-N-nitro-N-nitrosoguanidine followed by an enrichment protocol yielded 46 temperature-sensitive (ts) clones. A rapid assay for the allosterically regulated Mn-ribonucleotide reductase (RRase) was developed with nucleotide-permeable cells of C. ammoniagenes in order to screen for possible defects in DNA precursor biosynthesis at elevated temperature. Three mutants (CH 31, CH 32, and CH 33) grew well at 30 degrees C but did not proliferate at 40 degrees C because they did not reduce ribonucleotides to 2'-deoxyribonucleotides. They were designated nrdts (nucleotide reduction defective). When the cultures were shifted from 30 to 40 degrees C, the nrdts mutants immediately ceased to incorporate radiolabeled nucleic acid precursors into the DNA fraction, while DNA chain elongation was barely affected. Thus, exhaustion of the deoxyribonucleotide pool ultimately inhibited cell division, leading to a filamentous growth morphology. In contrast to the wild-type, all three nrdts mutants displayed a distinctly enhanced sensitivity of ribonucleotide reduction towards hydroxyurea (in permeabilized cells and in vitro) at 30 degrees C. The results from assays for biochemical complementation of heat-inactivated (2 min, 37 degrees C) mutant enzyme with either the small or the large subunit of wild-type Mn-RRase located the mutational defect on the large subunit.