Diploid/tetraploid/t(1;6) mosaicism in a 17-year-old female with hypomelanosis of Ito, multiple congenital anomalies, and body asymmetry.

Many types of chromosome mosaicism have been identified in cases of hypomelanosis of Ito, often in association with chromosome instability; however, there have been very few cases with diploid-tetraploid mosaicism described in the literature. We present a patient with a tetraploid mosaicism: a 17-year-old girl who has hypomelanosis of Ito in association with diploid/tetraploid/t(1;6) mosaicism. She had multiple congenital anomalies of omphalocele, exstrophy of bladder, duodenal web, and imperforate anus. These features have not been described previously in diploid-tetraploid mosaicism.

Identification of a dup(5)(p15.3) by multicolor banding.

A 7-year-old female was referred to the Genetics Clinic because of developmental delay and attentional difficulty. The patient was adopted and there was a nonspecific prenatal history of drug and alcohol abuse. The patient had clinical signs that were not compatible with typical fetal alcohol syndrome (FAS), although there was a history of alcohol exposure in utero, neurodevelopmental difficulties with learning and behavioral problems, and mild dysmorphisms. Cytogenetic analysis revealed an unbalanced female karyotype with a dup(5) containing additional chromosome 5 material at band 5p15.3. The dup(5) showed normal copy number of the cri-du-chat region on 5p15.2 using locus-specific probes D5S721 and D5S23. Multicolor banding of chromosome 5 (MetaSystems) using partial chromosome paint (pcp) probes showed a duplication of band 5p15.3. The karyotype of the patient was therefore interpreted as follows: 46,XX,add(5)mat.ish dup(5)(p15.3)(wcp5 +, D5S271 +, D5S23 +, C84C11/T3 + +, pcp5p15.3 + +). The patient's biological mother and maternal half-brother were found to carry the identical chromosome duplication. The clinical phenotype of the biological mother is complicated by a difficult lifestyle but there were apparent learning and behavioral difficulties at school. The half-brother is nondysmorphic and presents with learning problems and attention deficit disorder (ADD). His physical examination was normal. To the best of our knowledge, this is the first report of a limited duplication of 5p15.3. The clinical significance of the dup(5)(p15.3) is still uncertain but may be the basis for learning and attention difficulties.

Determination of acetochlor in technical and formulated products by capillary gas chromatography: PVM 5:1999.

A peer-verified gas chromatographic (GC) method is presented for the weight percent (wt %) determination of acetochlor herbicide in technical and formulated products. During method development, the method was found to be rugged by the Youden Ruggedness Test. Two laboratories with experience in the wt % determination of acetochlor in various matrixes participated in this study. Each laboratory received 10 blind duplicate test samples of the following 5 matrixes: one acetochlor technical and 4, different, emulsifiable concentrate (EC) formulations--Harness EC (MON 5841), Harness Export/Fist (MON 8435), Surpass EC (HF), and Surpass EC (LF). Each participant was asked to make duplicate weighings of each of the test samples and to inject each test sample solution twice. All test samples were analyzed on the same day, and 8 data points (replicates) per matrix were obtained. The test samples were dissolved in acetone that contained dipentyl phthalate as an internal standard. They were analyzed by GC on a 15 m capillary column by using split injection and a flame ionization detector. Acetochlor (wt %) was determined by comparing the ratios of peak area of acetochlor/peak area of dipentyl phthalate internal standard obtained for the test sample and calibration solutions. Repeatability of the method, expressed as the within-laboratory (between replicates) relative standard deviation (RSDr), was found to be 0.09-0.77% for the 5 matrixes. Reproducibility of the method, expressed as the within-test sample relative standard deviation (RSDR), was found to be 0.18-0.78% for the

Addiction and the brain: the role of neurotransmitters in the cause and treatment of drug dependence.

Recent scientific advances have led to a greater understanding of the neurobiological processes that underlie drug abuse and addiction. These suggest that multiple neurotransmitter systems may play a key role in the development and expression of drug dependence. These advances in our knowledge promise not only to help us identify the underlying cause of drug abuse and dependence, but also to aid the development of effective treatment strategies.

Prenatal diagnosis of holoprosencephaly (HPE) in a fetus with a recombinant (18)dup(18q)inv(18)(p11.31q11.2)mat.

Alobar holoprosencephaly (HPE) was identified by ultrasonography at 18 weeks' gestation in a fetus of a 29-year-old G2P0A1 woman. HPE has been described in association with various chromosomal anomalies. Amniocentesis was performed and a rearrangement of chromosome 18 resembling an isochromosome for the long arm of chromosome 18 was found. Subsequently, the mother was found to have a pericentric inversion of chromosome 18 with breakpoints at p11.31 and q11.2. The karyotype of the fetus was re-interpreted as 46,XX, rec(18)dup(18q)inv(18)(p11.31q11.2)mat. This is the first case of a parental inversion leading to a deficiency of 18p11.31 to 18pter associated with HPE.

Novel assay for Roberts syndrome assigns variable phenotypes to one complementation group.

Roberts syndrome (RS) is a rare autosomal recessive disorder characterized by heterogeneous clinical features, the most notable being tetraphocomelia, cleft lip, and cleft palate. Cells derived from most RS patients exhibit abnormal cytogenetic and cellular phenotypes that include the premature separation of para- and pericentromeric heterochromatin visible on C-banded metaphase chromosomes, a phenomenon referred to as heterochromatic splaying. Previously, it was shown that these abnormal phenotypes can be complemented following somatic cell hybridization between RS cells and control cells. In the current study, a permanent cell line was established from a new RS patient with a more severe phenotype than represented by previously established cells in culture. With a newly developed assay designed to facilitate rapid evaluation of in vitro complementation, we assigned this new patient to the same genetic complementation group defined by other, less severely affected patients. The results demonstrate that a single complementation group defines RS patients with heterochromatic splaying regardless of clinical severity.

Effect of 5-HT(1B) receptor ligands on self-administration of ethanol in an operant procedure in rats.

Recent evidence suggests that 5-HT(1B) receptor activation modifies ethanol's reinforcing, intoxicating and discriminative stimulus effects. The present study further explored the role played by 5-HT(1A/1B) receptors by examining their influence on oral ethanol self-administration. Male Wistar rats were trained on an FR 4 schedule to obtain a reinforcer of 0.1 12% w/v ethanol solution. Once responding was stable, the effect of the 5-HT(1A/1B) agonist RU24969 alone and in combination with the 5-HT(1B) antagonist GR127935 or the 5-HT(1A) antagonists (+) WAY100135 and (+) WAY100635 was assessed. The effect of RU24969 on ethanol's pharmacokinetic profile and on operant oral saline self-administration was also examined to assess if alterations in oral ethanol self-administration were due to nonspecific effects on level pressing. For comparison, we examined the effect of another 5-HT(1A/1B) agonist, CGS12066B, on oral ethanol self-administration. Both RU24969 (0.1 to 1 mg/kg) and CGS12066B (0.1 to 1 mg/kg) significantly suppressed oral ethanol self-administration. Administration of GR127935 (1 mg/kg), significantly reversed the effects elicited by RU24969, whereas neither WAY100635 (1 mg/kg) nor (+)WAY100135 (1 mg/kg) had any effect. The effects of lower doses of RU24969 on oral ethanol self-administration were selective as oral saline self-administration and blood ethanol levels were not altered by these doses. These data demonstrate that 5-HT(1B) receptor activation suppresses oral ethanol self-administration. These studies provide further evidence that 5-HT(1B) receptors play a modulatory role in ethanol's behavioral effects.

Holoprosencephaly, sacral anomalies, and situs ambiguus in an infant with partial monosomy 7q/trisomy 2p and SHH and HLXB9 haploinsufficiency..

We report an infant with holoprosencephaly (HPE), sacral anomalies, and situs ambiguus with a 46,XY,der(7)t(2;7)(p23.2;q36.1) karyotype as a result of an adjacent-1 segregation of a t(2;7)pat. The chromosomal abnormality was diagnosed prenatally after sonographic detection of HPE in the fetus. The baby was born at 37 weeks gestation, and died in the newborn period; he had dysmorphic features consistent with HPE sequence. Postmortem internal evaluation showed semilobar HPE, abdominal situs ambiguus, multiple segments of bowel atresia, dilatation of the ureters, and bony sacral anomalies. Molecular analysis confirmed hemizygosity for the SHH and HLXB9 genes, which are likely to be responsible for the HPE and sacral phenotypes, respectively. Immunohistochemical studies showed intact dopaminergic pathways in the mesencephalon, suggesting that midbrain dopamine neuron induction appears to require only one functioning SHH allele.

Cytogenetic aspects of the Canadian early and mid-trimester amniotic fluid trial (CEMAT).

Cytogenetic results from a large multicentre randomized controlled study of 2108 amniotic fluids obtained at 11+0-12+6 weeks (EA) and 1999 fluids at 15+0-16+6 weeks (MA) were compared. There was no statistically significant difference in the rate of chromosome abnormalities (EA =1.9 per cent; MA=1.7 per cent) or level III mosaicism (EA=0.2 per cent; MA= 0.2 per cent) between the groups. Level I and Level II mosaicism occurred more frequently in MA. Maternal cell contamination was not significantly different between the groups, but maternal cells only were analysed from one bloody EA fluid. The number of repeat amniocenteses because of cytogenetic problems was 2.2 per cent in the EA group compared with only 0.3 per cent in the MA group. On average, culture of EA fluids required one day more than MA fluids. Although both culture success (97.7 per cent) and accuracy (99.8 per cent) were high for patients randomized to the EA group, routine amniocentesis prior to 13 weeks' gestation is not recommended for clinical reasons including an increased risk of fetal loss and talipes equinovarus.

De novo deletion 12q: report of a patient with 12q24.31q24.33 deletion.

We report on a patient with de novo interstitial deletion of the long arm of chromosome 12: 46,XY,del(12)(q24.31q24.33). To our knowledge this is the first patient with this chromosomal abnormality reported. He was born with minor anomalies, ambiguous genitalia, tracheomalacia, and he was developmentally delayed at age 9 months. The phenotype associated with this deletion may be characteristic. However, because of the absence of reported cases of other patients with loss of this chromosomal region, we cannot delineate the specific phenotype further. Ambiguous genitalia or hypogonadism has been reported in other patients with chromosomal rearrangements involving 12q24.

Differences in propensity for drinking alcohol are reflected in subunit- and region-specific GABA(A) receptor levels.

Enhancement of GABA(A) receptor activity within certain discrete brain areas can elicit increased ethanol consumption, supporting a regionally specific role for GABAergic mechanisms in modulating ethanol reinforcement. The present study investigated if rats, which were in the highest (HES) or lowest (LES) 15th percentile of ethanol self-administration, had different GABA(A) receptor levels. MaleWistar rats (n=30) were trained to self-administer ethanol for 8 weeks followed by assessment of GABA(A) receptor mRNAs. In the last operant session the HES rats (4/group) were consuming significantly more ethanol than the LES rats (1.31+/--0.31 g/kg versus 0.02+/-0.02 g/kg; p<0.001). Significant GABA(A) receptor mRNA differences were found between the groups, which were subunit- and brain region-specific, with higher mRNA levels in the HES rats in the dorsal raphe (α2, α3, γ1), medial raphe (α3, α, ß1, ß3, γ1), cerebellum (α1, α6, ß3, γ2long) and hippocampus (ß1, ß3, γ1 and γ2long). The elevated cerebellum alpha1 mRNA level in the HES rats was confirmed using Western blotting (mean density units +/-SEM; LES rats 0.460 +/-0.005 versus HES rats 0.610 +/- 0.006, p=0.03). These data suggest that the differences in GABA receptors were due either to the different propensities of the groups to consume ethanol or were caused by their differing ethanol exposure.

Development and characterization of immortalized fibroblastoid cell lines from an FA(C) mouse model.

Fanconi anemia (FA) is an autosomal recessive disorder, characterised by multiple congenital malformations, bone marrow failure and a predisposition to developing malignancies, especially leukemia. FA cells show increased levels of spontaneous chromosomal aberrations and a hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC) and diepoxybutane (DEB). There are at least eight complementation groups involved in FA, and the genes for two of these groups, FA(A) and FA(C), have been isolated and cloned. Mouse models for FA(C) have been developed by replacing exon 8 or exon 9 of Fac with the neo gene. Mice homozygous for Fac mutations show reduced fertility and hypersensitivity to induction of chromosomal aberrations by MMC and DEB. To facilitate the study of cellular defects in vitro, transformed mouse fibroblast cell lines were established. Cell-killing experiments and cytogenetic analyses were performed on these cells following treatment with MMC and DEB. Fac-/- showed significant hypersensitivity to MMC and DEB as compared with Fac+/+ and +/- for both cellular phenotypes. This is consistent with results obtained from similar studies on human fibroblasts and lymphoblastoid cell lines. Therefore, these isogenic transformed mouse fibroblasts provide as in vitro model for further investigation of the hypersensitivity of Fanconi anemia cells to DNA cross-linking agents.

Effect of pentylenetetrazole on ethanol intake, ethanol kinetics, and social behavior in male Wistar rats.

Stress and anxiety are often implicated in excessive alcohol use. The nature of this interaction, however, is not understood. The aim of this study was to examine the effect of the anxiogenic agent, pentylenetetrazole (PTZ), on the acquisition and maintenance of ethanol drinking behavior in male Wistar rats. In rats maintained on a limited access procedure, with a choice between a 12% w/v ethanol (ETOH) solution and water available for 30 min each day, acute PTZ administration (1.5 to 15.0 mg/kg) did not modify ETOH intake. Chronic PTZ administration elicited a significant suppression in ETOH intake; however, this effect developed gradually over time. During the acquisition phase, chronic PTZ treatment also suppressed ETOH consumption. Chronic, but not acute, treatment with PTZ seemed to enhance water consumption. To assess whether the effect of PTZ on ETOH intake was due to either alterations in ETOH kinetics or behavior, blood ETOH levels and social interaction behaviour were examined. PTZ (15.0 mg/kg) produced a significant suppression in social interaction behavior, although tolerance developed to this effect on chronic PTZ administration. Both acute and chronic PTZ treatment (15 mg/kg) resulted in lower blood ETOH levels achieved after administration of 1.0 g/kg po of ETOH. Because the anxiogenic effect of PTZ was not maintained on repeated administration, yet the suppression of ETOH intake was only observed after chronic treatment, this suggests a dissociation between the processes regulating these behaviors.

Multiple congenital anomalies in a fetus with 45,X/46,X,r(X)(p11.22q12) mosaicism.

Ring X chromosomes that do not undergo inactivation may cause malformations and mental retardation. We report on a fetus with anencephaly, total dorsal rachischisis, and diaphragmatic hernia that was found to have a mosaic 45,X/46,X,r(X)(p11.22q12) karyotype. Fluorescent in situ hybridization (FISH) confirmed that the ring chromosome was X-derived. This report expands the phenotypic spectrum of mosaic monosomy X and small ring X chromosomes.

Facilitatory effect of thinking about movement on magnetic motor-evoked potentials.

To investigate the facilitatory effect of thinking about movement on motor evoked potential (MEP) amplitude, we recorded MEPs in two test muscles during rest, with the subject thinking about contracting the test muscle but without subsequent contraction, and during 10% maximum voluntary contraction. Stimuli were delivered at 10% above resting motor threshold and at 90-100% stimulator output. H-reflexes, recorded in flexor carpi radialis, were obtained during rest and think conditions. MEP threshold was lower during the think condition (P = 0.004). At both stimulus intensities, median MEP amplitudes and areas were significantly (P < 0.001) larger during the think paradigm compared with rest. This effect was greater at the lower stimulus intensity. There was no significant difference in latency (P = 0.15). In 4/8 subjects, H-reflex amplitudes were mildly facilitated (P < 0.05) during the think condition. We conclude that thinking about movement without detectable EMG activity has a facilitatory effect on magnetic MEPs. The absence of a MEP latency shift between rest and think conditions and absence of a consistent increase in H-reflex amplitude suggests this effect occurs largely at the cortical level. In some subjects, however, an increase in spinal motoneuron excitability may also contribute.

Effect of CYP2D1 inhibition on the behavioural effects of d-amphetamine.

In rats, amphetamine (AMP) conversion to 4-OH-AMP is metabolized by CYP2D1, the rat equivalent of the human enzyme CYP2D6. To determine the impact of impaired AMP metabolism on its behavioural effects, AMP-induced hyperactivity, AMP discrimination and AMP self-administration were examined in male Wistar rats with or without pretreatment with the CYP2D1 inhibitors quinine and budipine. In vivo, quinine (20 mg/kg) and budipine (10 mg/kg) increased the plasma area under the curve of AMP 4-fold and 3.6-fold respectively, and decreased the plasma levels of 4-OH-AMP, 3-fold and 8.6-fold, confirming that the doses used suppressed CYP2D1 activity. Both inhibitors prolonged AMP-induced hyperactivity (0.3 mg/kg) and prolonged the duration of AMP-appropriate responding for periods of up to 90 min post-AMP administration in a drug discrimination procedure. In rats given a preload dose of AMP (0.8 mg/kg) 3 h prior to the self-administration test session, CYP2D1 inhibition resulted in fewer AMP infusions being taken compared with rats receiving the AMP preload dose alone. These studies indicate that AMP is responsible for the behavioural effects seen in rats and that a rat phenocopy model of the human CYP2D6 deficiency state can be produced by CYP2D1 inhibitors.

Effects of 5-HT3, D1 and D2 receptor antagonists on ethanol- and cocaine-induced locomotion.

The effects of acute treatment with 5-HT3 receptor antagonists, ondansetron and ICS 205-930, on the stimulation of activity induced by ethanol-and cocaine were examined. Ethanol (1.8 or 2 g/kg i.p.) or cocaine (15 mg/kg i.p.) produced a significant increase in locomotor activity (LMA) in DBA/2N mice. Pretreatment with ondansetron or ICS 205-930, in doses ranging from 0.001 to 0.1 mg/kg (s.c), did not modify ethanol or cocaine induced stimulation of activity. In contrast, pretreatment with a 10 micrograms/kg dose of either SCH 23390 or spiperone, a D1 and D2 dopamine (DA) receptor antagonist respectively, completely antagonized the stimulation of LMA induced by ethanol. Similar dose of SCH23390, but not spiperone, blocked the stimulation of activity induced by cocaine. These results indicate that D1 but not D 2 DA receptors play a significant role in cocaine induced hyperactivity whereas both D1 and D2 are involved the locomotor activating effects of ethanol.

Surface-relief diffraction gratings recorded by multiple-beam coherent phase exposure.

Surface-relief hexagonal-array diffraction gratings have been produced by three-beam coherent exposure. Collimated light was used in an attempt to produce a uniform relief profile over the total area of a 7.6-cm plate coated with a positive photoresist. The resulting gratings were reproduced in nickel by an electroforming process and analyzed by atomic force microscopy. The topography of the gratings was found to be that predicted by theory. The results obtained show that the gratings were of uniform profile over their total area.

Effect of cytochrome P450 2D1 inhibition on hydrocodone metabolism and its behavioral consequences in rats.

Humans that lack cytochrome P450 2D6 (CYP2D6) activity may have an altered risk of drug dependence or abuse because this enzyme is important in the metabolism of some drugs of abuse, including hydrocodone. In rats, hydrocodone conversion to hydromorphone is catalyzed by CYP2D1, the rat homolog of the human CYP2D6. To determine the impact of impaired hydromorphone formation on the behavioral effects of the parent compound, hydrocodone-induced analgesia and hyperactivity, hydrocodone discrimination and self-administration were examined in male Wistar rats, with or without pretreatment with CYP2D1 inhibitors (quinine and budipine). In vivo, quinine (20 mg/kg) and budipine (10 mg/kg) produced a marked suppression in brain and plasma hydromorphone levels detected after the peripheral administration of hydrocodone, thus confirming that the doses used suppressed CYP2D1 activity. In contrast, CYP2D1 inhibition had no impact on the analgesic or discriminative stimulus effects of hydrocodone, nor did this type of manipulation alter hydrocodone self-administration. The effects of quinine on the locomotor activating effects of hydrocodone were subtle at best. Because inhibition of CYP2D1 in this rat strain is proposed to be a useful animal counterpart for studying the impact of CYP2D6 polymorphism in humans, these data suggest that differences in CYP2D6 phenotype will have limited influence on the drug response to hydrocodone after nonoral administration. This has recently been verified in a study showing that inhibition of hydrocodone biotransformation to hydromorphone does not affect measures of abuse liability. Therefore, hydrocodone's behavioral effects are most likely attributable to its own intrinsic effects at mu opioid receptors.

Risk of congenital anomalies in children of parents occupationally exposed to low level ionising radiation.

OBJECTIVES: To evaluate the risk of having a child with a congenital anomaly in relation to occupational exposure to low level ionising radiation in the pre-conception period. METHODS: A case-control study based on the Canadian congenital anomalies registry used record linkage techniques to identify congenital anomalies among male and female workers in Canada's largest electric company. Cases were defined as parents of a child with a congenital anomaly born between April 1979 and December 1986 who had a congenital anomaly diagnosed within the first year of life. Controls were an individually matched sample of parents of a liveborn child without an anomaly. Risk of congenital anomaly was assessed in relation to parental exposure to ionising radiation acquired through work within a nuclear generating station of an electric power company. Exposure was assessed according to employment, whether or not the worker was monitored for radiation exposure, and quantitative estimates of radiation dose. RESULTS: Employment within the electric power industry was not associated with an increased risk of congenital anomalies in the offspring of mothers or fathers. Risk estimates for workers monitored (those who are likely to be exposed to ionising radiation) were 1.75 (95% confidence interval (95% CI) 0.86 to 3.55) for mothers and 0.84 (95% CI 0.68 to 1.05) for fathers. Exposure for fathers before conception, defined cumulatively and for six months before conception, was not associated with increased risk of anomalies in their offspring. There were no significant increases in risk found between type of anomaly and any measure of exposure, although the statistical power in these groups was limited. The study had insufficient numbers to evaluate the effects of ionising radiation in mothers as only three mothers had recorded doses > 0 mSv. CONCLUSIONS: Overall, workers in a nuclear power industry, and specifically those exposed before conception to low levels of ionising radiation, do not appear to be at an increased risk of having a liveborn child with a congenital anomaly.