Growth control in the ontogenetic and regenerating zebrafish fin

The growth and regeneration of the zebrafish fin provide yet another opportunity to exploit genetics to study important vertebrate problems. Mutants have been identified in zebrafish that affect the development of the embryonic fin, disrupt the normal growth relationship of fin and body, or disrupt the regeneration of the fin. Analysis of a regeneration mutation suggests that the developmental checkpoints that ensure developmental integrity in normal growth are absent in the early stages of regeneration. These stages correspond to the only time in fish developmental when differentiated bone cells divide.

Word learning in the context of referential and salience cues

Adult referential behavior (gaze direction) and salience (target activation) were independently manipulated in a study of novel word learning. Children (seventy-five 18-month-olds and seventy-two 24-month-olds) were trained in different conditions with a novel word in the context of 2 remote-controlled toys. In response to the novel word at test, 24-month-olds tended to pick out the toy to which the adult referred in all conditions. They also tended to use the novel word appropriately. Comprehension by 18-month-olds was good when the salience of the toy did not conflict with the adult's referential intent, but it was disrupted when referential and salience cues conflicted and when referential cues were not available. Results imply that, at 24 months, children use the referential intent of the speaker to learn new words, but when first learning words, children may have a less secure grasp on the meaning of speakers' referential cues.

Risky single-occasion drinking amongst young people--definition, correlates, policy, and intervention: a broad overview of research findings

Risky single-occasion drinking (RSOD) has dire consequences upon health and well-being including unplanned pregnancies, sexually transmitted diseases such as HIV/AIDS, crime, and car accidents. The prevalence of RSOD among young people is alarming. Despite this, as yet, a review of existing literature on RSOD amongst young people is lacking. This article will provide an overview of this area of research focusing on the definition of RSOD, its prevalence among young people, health and behavioural effects of RSOD, the perceived risk of RSOD among young people, and interventions to reduce RSOD in young people. In addition, recommendations are made for health educators interested in reducing the incidence of RSOD in young people.

A direct correlation between nicotinamide N-methyltransferase activity and protein levels in human liver cytosol

Phenotypic differences in nicotinamide N-methyltransferase (NNMT, E. C. 2.1.1.1) activity may be due to a genetic polymorphism. We report the characterisation of the hepatic NNMT activity in cytosol from normal human livers, enzyme protein levels determined by Western blotting and ELISA and mRNA levels determined by SDS-PAGE/Northern blotting. Subjects with high NNMT activity had high levels of NNMT protein and NNMT mRNA levels in hepatic cytosol and the converse was true for individuals with low NNMT activity. No differences in sequences were seen when cDNAs of individuals with high and low NNMT activity were compared. Thus phenotypic differences in the general population are due to differences in steady-state mRNA levels and not because of a polymorphism in the coding region of the NNMT gene.

Evidence for a chromosome 2p13-14 schizophrenia susceptibility locus in families from Palau, Micronesia

A large multiplex schizophrenia pedigree ascertained from the Micronesian nation of Palau was genotyped with 406 microsatellite DNA markers evenly distributed throughout the genome. Assuming autosomal dominant inheritance, the highest genome-wide lod scores were found for DNA loci mapping to 2p13-14; the maximum lod score was 2.17 (theta = 0.05) at D2S441. A nonparametric APM analysis was also suggestive at D2S441 (APM score = 2.96, P = 0.011). Of the 14 affected cases in this extended family, eight share a large haplotype in this region spanning approximately 11 cM. When 16 other families containing 65 schizophrenic cases were typed in a follow-up study of this region, the maximum lod score remained positive (maximum at D2S441 1.69, theta = 0.20). APM results also remained positive at D2S441 for all 17 families (APM score = 4.87, P = 0.0006). The linkage and haplotype sharing results provide suggestive evidence for a 2p locus predisposing to schizophrenia in a subset of families in the Palauan population.

Direct genetic evidence for involvement of tau in progressive supranuclear palsy. European Study Group on Atypical Parkinsonism Consortium

OBJECTIVE

To confirm whether a dinucleotide repeat sequence in an intron of the microtubule-associated protein tau is associated with progressive supranuclear palsy (PSP) in an independent study population and to establish an improved methodology for allelotyping.

BACKGROUND

It has recently been reported that a genetic variant of tau, known as the A0 allele, was represented excessively in PSP patients when compared with control subjects.

METHODS

In a multicenter study, the authors examined the allelic distribution of this dinucleotide repeat marker in a set of clinically ascertained PSP patients (n = 30), multiple system atrophy (MSA) patients (n = 35), and matched control subjects (n = 70). Individuals were allelotyped using automated analysis of fluorescently labeled PCR products.

RESULTS

The A0 allele was significantly overrepresented in the PSP patients (93.3% versus 76.4%; p = 0.0067; odds ratio [OR] = 4.33; 95% confidence interval [CI], 1.36 to 13.60), but not in the MSA patients. Likewise, A0 homozygotes were overrepresented in the PSP group (86.7% versus 61.1%; p = 0.02; OR = 4.14; 95% CI, 1.19 to 14.48) compared with control subjects.

CONCLUSIONS

The findings of this study, which is the largest to date, support those of a previous investigation that used pathologically confirmed PSP patients. These data provide additional strong evidence that genetic variation at or near the tau gene plays an important role in the pathogenesis of PSP.

Changes in the expression of the type-2 but not the type-1 cyclo-oxygenase enzyme in chorion-decidua with the onset of labour

OBJECTIVE

To determine the relative expression of cyclo-oxygenase (COX)-1 and COX-2 in the chorion-decidual part of human fetal membranes following delivery at term and to identify any changes in expression associated with labour.

METHODS

Fetal membranes were collected from 12 term pregnancies before labour following elective caesarean section and from 12 spontaneous vaginal deliveries. Expression of COX-1 and COX-2 mRNA was measured using a previously validated quantitative RT-PCR assay.

RESULTS

COX-2 expression exceeded that of COX-1 by approximately eight-fold. COX-1 expression did not change but COX-2 expression was found to increase four-fold with labour.

CONCLUSIONS

Chorion-decidua has the capacity to contribute to the increase in prostaglandin synthesis within the uterus associated with labour. As in the amnion, it is COX-2 and not COX-1 which is upregulated with labour. COX-2 selective anti-prostaglandins should therefore be as effective as nonselective drugs in inhibition of fetal membrane prostaglandin synthesis.

Detection of fetal messenger ribonucleic acid in maternal blood to determine fetal RhD status as a strategy for noninvasive prenatal diagnosis

OBJECTIVES

Our purpose was to test the hypothesis that reverse transcriptase-polymerase chain reaction for fetal messenger ribonucleic acid in maternal blood is more sensitive than polymerase chain reaction from genomic deoxyribonucleic acid in prenatal determination of fetal RhD blood type.

STUDY DESIGN

Fetal nucleated erythrocytes in peripheral blood from 35 RhD-negative women were enriched by triple-density gradient centrifugation, anti-CD71 magnetic sorted, and deoxyribonucleic acid and ribonucleic acid extracted. Sensitivities of reverse transcriptase-polymerase chain reaction and polymerase chain reaction were compared to predict definitive fetal RhD blood type determined in fetal tissues.

RESULTS

Reverse transcriptase-polymerase chain reaction was significantly more accurate (P = .03) than genomic-polymerase chain reaction in predicting fetal RhD blood type, both overall (28 of 35 vs 22 of 35) and when the fetus was RhD-positive (12 of 19 vs 6 of 19).

CONCLUSIONS

Reverse transcriptase-polymerase chain reaction is more sensitive than genomic-polymerase chain reaction in detection of fetal RhD sequences in maternal blood.

Understanding binge drinking among young people: an application of the Theory of Planned Behaviour

Binge drinking (i.e. consuming half the recommended weekly consumption of alcohol in a single session) is a common activity among young people. Using the Theory of Planned Behaviour as its theoretical framework, this paper reports a study exploring the motivational and attitudinal factors underlying binge drinking in a sample of undergraduate students. Questionnaires were completed by 136 undergraduates which focused on their drinking behaviour and their beliefs about binge drinking. Binge drinking was found to be more prevalent among male respondents, and a number of significant differences in the beliefs of male and female respondents were found which supported this difference in drinking behaviour. A regression analysis identified two key predictors of the frequency of binge drinking; these being positive control beliefs and perceived behavioural control. Frequent binge drinkers were more likely to recognize the influence of a range of factors which may serve to encourage binge drinking (e.g. celebrating an event) and less likely to believe that the decision to engage in binge drinking is under their control. The results are discussed in relation to measures which may help to reduce the incidence of binge drinking through changes in the social environment.

Expression of the insulin-like growth factors and their receptors in term placentas: a comparison between normal and IUGR births

Intrauterine growth retardation (IUGR) is defined as growth retarded to be below the tenth centile. The insulin-like growth factors and their receptors are implicated in pre- and postnatal growth and development, and it is believed that alteration in their activity may contribute to IUGR. In this study nine normal and nine intrauterine growth retarded births were followed and term placentas examined for expression of the insulin-like growth factors and their receptors. It was found that the expression of insulin-like growth factor 1 (IGF1), insulin-like growth factor 2 (IGF2), and the insulin, IGF1 and IGF2 receptor transcripts (IGF1R and IGF2R, respectively) was present in all term placentas examined. Expression of insulin was not detected. Quantitative polymerase chain reaction (PCR) was used to compare transcription levels in term placentas from normal with IUGR births. There was no significant difference in the levels of transcripts for IGF1, insulin receptor, or IGF2R between normal and IUGR term placentas. However, the IUGR term placentas had significantly higher levels of IGF2 and IGF1R expression compared with the normal term placentas. The increase in the transcription of IGF2 and IGF1R in IUGR term placentas may represent a counter regulatory mechanism in response to the growth retardation.

Absence of expression of RhD by human trophoblast cells

OBJECTIVE

Our purpose was to determine whether the RhD gene is expressed in trophoblast at any stage of gestation.

STUDY DESIGN

Trophoblast and fetal tissue were obtained from 18 pregnancies at 8 to 40 weeks' gestation. Deoxyribonucleic acid and ribonucleic acid were extracted from trophoblast. Complementary deoxyribonucleic acid was synthesized from ribonucleic acid, and reverse transcriptase-polymerase chain reaction was performed using primers specific for the RhD gene. Deoxyribonucleic acid was extracted from fetal tissue to determine the fetal RhD status by means of polymerase chain reaction. Antigen expression was also sought by analytic cytometric analysis (flow cytometry and immunocytochemistry) using a monoclonal anti-D antibody.

RESULTS

Trophoblast was studied from various combinations of RhD-positive and RhD-negative fetuses (on deoxyribonucleic acid) from mothers to find no RhD gene expression in any sample. Flow cytometry and immunocytochemistry confirmed this by demonstrating no RhD antigen sites on trophoblast cells.

CONCLUSION

Contrary to a previous report, we conclude that the RhD gene is not expressed in human trophoblast in any trimester.

Intrahypothalamic growth hormone feedback: from dwarfism to acromegaly in the rat

Two different dwarf rat models with primary (dw/dw, DW) or secondary (transgenic growth retarded, WF/Tgr) GH deficiency and contrasting hypothalamic GH-releasing hormone (GHRH) and somatostatin (SRIH) expression were implanted sc with GC cells. These form encapsulated rat GH-secreting tumors that maintain high plasma rat GH levels for several weeks. In both strains, GC cell tumors stimulated growth and raised GHBP levels, without affecting pituitary GH content. In DW rats, GC cell implants increased SRIH expression in the periventricular nucleus (PeV), but not in the arcuate nucleus (ARC), whereas their high GHRH expression in ARC was decreased by GC cells. In contrast, GC cell implants in WF/Tgr rats had little effect on the already high SRIH expression in PeV or low GHRH expression in ARC, although they reduced SRIH expression in ARC. GC cell implants also reduced GH receptor expression in both ARC and PeV in the WF/Tgr dwarves. Thus, chronic GH overexposure stimulates rapid growth in both dwarf strains, but has differential hypothalamic effects in these models. This experimental approach now makes it possible to study the effects of pathophysiological concentrations of GH ranging from dwarfism to acromegaly in the same animal model.

Health locus of control and value for health in smokers and nonsmokers

A representative sample of 11,401 persons completed a questionnaire, including measures of health locus of control, value for health, and smoking frequency. Smokers held stronger internal, chance, and powerful others beliefs than never smokers. Ex-smokers had lower scores on internal and chance dimensions and placed a higher value on their health than smokers. The interaction between chance health locus of control and value for health was a significant predictor of smoking status, suggesting that health value may moderate the relationship between health locus of control and smoking status. Within smokers, the health locus of control dimensions and value for health explained less than 1% of the variance in smoking frequency, with only the chance dimension emerging as a significant predictor.

Human cysteine dioxygenase type I (CDO-I; EC 1.13.11.20): 5' flanking region and intron-exon structure of the gene

AIM

The elucidation of the structure of the 5' flanking region and the exonic organisation of the human cysteine dioxygenase type I gene.

METHODS

Material for sequence studies was generated by polymerase chain reaction (PCR) methods using human genomic DNA, a cosmid clone containing the entire gene, and a commercial gene walking kit.

RESULTS AND CONCLUSIONS

The gene was found to be--12 kb in length and made up of five exons (418, 78, 155, 170, and 731 base pairs, respectively). The immediate 5' flanking region did not contain the canonical TATAA box. One DNA source (Clontech promoter finder kit) contained a liver specific nuclear factor response element approximately 550 base pairs from the transcription start site, whereas a second source did not. This and other cis acting factors in the 5' flanking region were identified by computer analysis. The physiological significance of such elements requires detailed experimental evaluation.

Expression of MCH and POMC genes in rainbow trout (Oncorhynchus mykiss) during ontogeny and in response to early physiological challenges

The expression of the neuropeptide melanin-concentrating hormone (MCH) in two groups of hypothalamic neurones (NLT- and LVR-MCH neurones), and POMC in the pituitary corticotropes and melanotropes, has been examined in rainbow trout larvae using immunocytochemistry and quantitative in situ hybridization. The aim was to establish at what stage in ontogeny these cells first respond to two physiological challenges-background color and stress. Trout reared in black or white trays showed adaptive skin pigmentary changes at 10 days posthatching, when fish in a pale environment abruptly exhibited melanin aggregation from a prior dispersed state, although the pigment cells were already competent to respond to adrenalin and MCH in vitro at 3 days. Immunoreactive MCH was detectable in the neurohypophysis at hatching and MCH mRNA in the NLT-MCH neurones (which project to the pituitary) was enhanced at 7 days in the white-reared trout. Immunostainable POMC was also present in the pars intermedia at hatching but their POMC mRNA was unaffected by tank color until 28 days, when it was enhanced in the black-reared trout. It is suggested that early pigment concentration depends on neural signals from the sympathetic nervous system in conjunction with MCH from the NLT rather than on a reduction in alphaMSH secretion from the pars intermedia. MCH mRNA in the LVR-MCH neurones was increased on a pale environment only 28 days after hatching, suggesting that these cells play little role in the early adaptive pigment response. Previous studies on the ontogeny of cortisol secretion indicate the hypothalamopituitary-interrenal axis can respond to stress by about 14 days. However, the pituitary ACTH cells showed no stress-induced changes in POMC mRNA until 28 days. ACTH release may therefore be dissociated from POMC transcription in the early stages of development. The LVR- and NLT-MCH neurones were both stimulated by stress, LVR-MCH mRNA responding by 14 days and NLT-MCH mRNA by 21 days. Melanotrope POMC mRNA was reduced by stress but the physiological significance of this is not known.