Microbial acceleration of aerobic pyrite oxidation at circumneutral pH

Pyrite (FeS₂ ) is the most abundant sulfide mineral on Earth and represents a significant reservoir of reduced iron and sulfur both today and in the geologic past. In modern environments, oxidative transformations of pyrite and other metal sulfides play a key role in terrestrial element partitioning with broad impacts to contaminant mobility and the formation of acid mine drainage systems. Although the role of aerobic micro-organisms in pyrite oxidation under acidic-pH conditions is well known, to date there is very little known about the capacity for aerobic micro-organisms to oxidize pyrite at circumneutral pH. Here, we describe two enrichment cultures, obtained from pyrite-bearing subsurface sediments, that were capable of sustained cell growth linked to pyrite oxidation and sulfate generation at neutral pH. The cultures were dominated by two Rhizobiales species (Bradyrhizobium sp. and Mesorhizobium sp.) and a Ralstonia species. Shotgun metagenomic sequencing and genome reconstruction indicated the presence of Fe and S oxidation pathways in these organisms, and the presence of a complete Calvin-Benson-Bassham CO₂ fixation system in the Bradyrhizobium sp. Oxidation of pyrite resulted in thin (30-50 nm) coatings of amorphous Fe(III) oxide on the pyrite surface, with no other secondary Fe or S phases detected by electron microscopy or X-ray absorption spectroscopy. Rates of microbial pyrite oxidation were approximately one order of magnitude higher than abiotic rates. These results demonstrate the ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro-organisms to continental sulfide mineral weathering around the time of the Great Oxidation Event to include neutral-pH environments. In addition, our findings have direct implications for the geochemistry of modern sedimentary environments, including stimulation of the early stages of acid mine drainage formation and mobilization of pyrite-associated metals.

High-resolution magnetic resonance imaging reveals nuclei of the human amygdala: manual segmentation to automatic atlas

The amygdala is composed of multiple nuclei with unique functions and connections in the limbic system and to the rest of the brain. However, standard in vivo neuroimaging tools to automatically delineate the amygdala into its multiple nuclei are still rare. By scanning postmortem specimens at high resolution (100-150µm) at 7T field strength (n = 10), we were able to visualize and label nine amygdala nuclei (anterior amygdaloid, cortico-amygdaloid transition area; basal, lateral, accessory basal, central, cortical medial, paralaminar nuclei). We created an atlas from these labels using a recently developed atlas building algorithm based on Bayesian inference. This atlas, which will be released as part of FreeSurfer, can be used to automatically segment nine amygdala nuclei from a standard resolution structural MR image. We applied this atlas to two publicly available datasets (ADNI and ABIDE) with standard resolution T1 data, used individual volumetric data of the amygdala nuclei as the measure and found that our atlas i) discriminates between Alzheimer's disease participants and age-matched control participants with 84% accuracy (AUC=0.915), and ii) discriminates between individuals with autism and age-, sex- and IQ-matched neurotypically developed control participants with 59.5% accuracy (AUC=0.59). For both datasets, the new ex vivo atlas significantly outperformed (all p < .05) estimations of the whole amygdala derived from the segmentation in FreeSurfer 5.1 (ADNI: 75%, ABIDE: 54% accuracy), as well as classification based on whole amygdala volume (using the sum of all amygdala nuclei volumes; ADNI: 81%, ABIDE: 55% accuracy). This new atlas and the segmentation tools that utilize it will provide neuroimaging researchers with the ability to explore the function and connectivity of the human amygdala nuclei with unprecedented detail in healthy adults as well as those with neurodevelopmental and neurodegenerative disorders.

Generation of a proinflammatory response by macrophage following infection with an O3:K6 serotype of Vibrio parahaemolyticus. (94.3)

Vibrio parahaemolyticus, a Gram-negative bacterium, is the leading cause of seafood-related bacterial gastroenteritis in the United States. This emerging pathogen can causes self-limiting gastrointestinal infection, wound infection, and, in the immunocompromised host, significant systemic disease, leading to death. The CDC has recently reported a 47% increase in the number of culture confirmed V. parahaemolyticus infections since 1996-1998. There is a dearth of literature regarding the host response to, and subsequent elimination of, infection with this pathogen. In order to elucidate the immune response to infection, we have developed an in vitro model using the virulent clinical isolate V. parahaemolyticus RIMD2210633, an O3:K6 serotype. First, we determined that this isolate could infect RAW264.7 cells, a murine macrophage cell line. Additionally, infection resulted in the simultaneous detection of 7-amino-actinomycin D (7-AAD) and annexin-V positive cells, suggesting cell death with a loss of membrane integrity. Lastly, infection resulted in the production of the early proinflammatory cytokines interleukin-1 alpha (IL-1α) and interleukin 6 (IL-6). We a currently investigating the cellular pathways involved in this proinflammatory response and macrophage cell death. Here, we have begun to investigate those aspects of the immune response required to eliminate this gastrointestinal pathogen from infected host tissues.

The value of interhospital transfer and emergency MRI for suspected cauda equina syndrome: a 2-year retrospective study

INTRODUCTION

The timing of surgery in cauda equina syndrome due to prolapsed intervertebral disc remains controversial. Assessment of these patients requires magnetic resonance imaging (MRI), which is of limited availability outside normal working hours in the UK.

PATIENTS AND METHODS

We reviewed radiological results in all patients undergoing emergency MRI within our unit for suspected cauda equina syndrome over a 2-year period, and all subjects undergoing emergency lumbar discectomy for cauda equina syndrome within the same period. Outcome measures were: proportion of positive findings in symptomatic patients and proportion of patients referred with diagnostic MRI scans undergoing emergency surgery. We also assessed outcomes of patients having surgery for cauda equina syndrome in terms of improvement of pain, sensory and sphincter disturbance.

RESULTS

A total of 76 patients were transferred for assessment and 'on-call' MRI; 27 were subsequently operated upon. Only 5 proceeded to emergency discectomy that night (prior to next scheduled list). This may be due to delays in timing--from referral to acceptance, to arrival in the department, to diagnostic scan and to theatre. With the second group of patients, 43 had emergency discectomy for cauda equina syndrome during the study period. Of these, 6 patients had an out-of-hours MRI at our hospital for assessment (one patient living locally). Most surgically treated patients experienced improvement in their pain syndrome, with approximately two-thirds experiencing improvement in sensory and sphincter disturbance.

CONCLUSIONS

These data support a policy of advising MRI scan for cauda equina syndrome at the earliest opportunity within the next 24 h in the referring hospital, rather than emergency transfer for diagnostic imaging which has a relatively low yield in terms of patients operated on as an emergency.

HGS-ETR1, a fully human TRAIL-receptor 1 monoclonal antibody, induces cell death in multiple tumour types in vitro and in vivo

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in a variety of tumour cells through activation of TRAIL-R1 and TRAIL-R2 death signalling receptors. Here, we describe the characterisation and activity of HGS-ETR1, the first fully human, agonistic TRAIL-R1 mAb that is being developed as an antitumour therapeutic agent. HGS-ETR1 showed specific binding to TRAIL-R1 receptor. HGS-ETR1 reduced the viability of multiple types of tumour cells in vitro, and induced activation of caspase 8, Bid, caspase 9, caspase 3, and cleavage of PARP, indicating activation of TRAIL-R1 alone was sufficient to induce both extrinsic and intrinsic apoptotic pathways. Treatment of cell lines in vitro with HGS-ETR1 enhanced the cytotoxicity of chemotherapeutic agents (camptothecin, cisplatin, carboplatin, or 5-fluorouracil) even in tumour cell lines that were not sensitive to HGS-ETR1 alone. In vivo administration of HGS-ETR1 resulted in rapid tumour regression or repression of tumour growth in pre-established colon, non-small-cell lung, and renal tumours in xenograft models. Combination of HGS-ETR1 with chemotherapeutic agents (topotecan, 5-fluorouracil, and irinotecan) in three independent colon cancer xenograft models resulted in an enhanced antitumour efficacy compared to either agent alone. Pharmacokinetic studies in the mouse following intravenous injection showed that HGS-ETR1 serum concentrations were biphasic with a terminal half-life of 6.9–8.7 days and a steady-state volume of distribution of approximately 60 ml kg⁻¹. Clearance was 3.6–5.7 ml⁻¹ day⁻¹ kg⁻¹. These data suggest that HGS-ETR1 is a specific and potent antitumour agent with favourable pharmacokinetic characteristics and the potential to provide therapeutic benefit for a broad range of human malignancies.

The application of comparative genomic hybridization as an additional tool in the chromosome analysis of acute myeloid leukemia and myelodysplastic syndromes

In acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) there are frequently complex karyotypes with multiple structurally altered chromosomes, many of which are marker chromosomes of unknown origin. The aim of this study was to apply comparative genomic hybridization (CGH) to cases of AML or MDS in transformation submitted for routine cytogenetic analysis to investigate whether this approach would yield any further information and, if possible, to predict which cases would benefit from CGH analysis. Nineteen cases with AML or MDS in transformation were analyzed. CGH revealed nine cases with gains or losses of chromosomal material. In six of these cases the chromosomal location of this material was not apparent from cytogenetic analysis especially when multiple markers were present. By using fluorescence in situ hybridization (FISH) with specific libraries for the chromosome regions that showed discordance between CGH and conventional cytogenetics, we were able to identify the chromosome location of material within the karyotype. In this group of six patients, four cases of an unbalanced translocation involving regions of chromosomes 5 and 17 were characterized. Three of these cases had additional abnormalities, including two cases with regions of amplification in which oncogenes are located (MYC, MLL) and one case with a dic(7;21)(p10;p10). In all six cases it was possible to characterize complex chromosomal aberrations such as derivative chromosomes, marker chromosomes, and ring chromosomes. This study demonstrates that CGH can detect true gain and loss of critical chromosome regions more accurately than conventional karyotyping in cases with very complex karyotypes, and can thus prove useful in predicting prognosis and pinpointing areas of the genome that require further study. Also, CGH can be a useful technique to identify the origin of marker chromosomes, and it can assist in choice of probes for confirmatory FISH, when there is no clue provided from the analysis of G-banded chromosomes.

Trends in prenatal diagnosis of Down syndrome and other autosomal trisomies in Scotland 1990 to 1994, with associated cytogenetic and epidemiological findings

The present report summarizes findings on 670 cases of autosomal trisomy diagnosed in Scotland, with actual or expected dates of delivery in 1990 to 1994 inclusive. Cases were notified by cytogenetic service laboratories. There were 277 prenatal and 369 postnatal diagnoses and 24 spontaneous losses. Excluding the latter, numbers diagnosed with trisomy 21, trisomy 18, trisomy 13, and other trisomies were, respectively, 470 (72.8%), 108 (16.7%), 36 (5.6%), and 32 (5.0%). Estimated maternal age-specific birth rates for trisomy 21 were close to published values from other jurisdictions. However, comparisons with a clinically based national register of congenital anomalies suggested that 3-4% of Down syndrome births were never karyotyped, most being early neonatal deaths. There was a striking increase over the period in the proportion of cases detected prenatally, associated with increased maternal serum screening in mothers <35 years old. Over the 3 final years (1992-1994), prenatal screening followed by elective termination was estimated to reduce the birth rate in trisomy 21 by 24% in mothers aged <35 years, by 57% in older mothers, and by 35% in all mothers. The crude incidence per 1,000 births fell from 1.08 in 1990-1991 to 0.77 in 1992-1994, in spite of an upward shift in the overall maternal age distribution. For trisomies 18 and 13, the estimated overall reductions in the birth rate over the whole 5-year period were respectively, 26 and 17%. In free trisomy 18, there was a significant reduction in the sex ratio (male/female) to 0.65, in line with earlier studies.

Spondylocarpotarsal synostosis syndrome and cervical instability

Spondylocarpotarsal synostosis syndrome is a recently delineated autosomal recessive condition comprising short stature with short trunk, failure of normal spine segmentation resulting in block vertebrae and fusion of posterior elements, carpal and/or tarsal coalition, scoliosis, lordosis, pes planus, dental enamel hypoplasia, decreased range of motion or dislocation of the elbow, renal anomalies, and hearing loss. The vertebral segmentation defects may involve noncontiguous areas of the cervical, thoracic, and lumbar spine. Odontoid hypoplasia was noted in two cases. We report on a sporadic case of spondylocarpotarsal synostosis in a 5-year-old girl with hypoplasia of C1 and odontoid and subluxation of C2 upon C3. This brings the number of well-documented cases of spondylocar- potarsal synostosis to 19, and is the first documenting cervical spine instability. Careful evaluation for this complication should be considered in other cases.

Meningeal worm in deer from western Nebraska

One hundred seventy-eight white-tailed deer (Odocoileus virginianus) and 275 mule deer (Odocoileus hemionus) collected from locker plants in the western 2/3 of Nebraska (USA) in November 1997 were examined for the meningeal worm (Parelaphostrongylus tenuis). Parelaphostrongylus tenuis was identified in 17 (10%) of 168 white-tailed deer and in one (<1%) of 273 mule deer. This is the first naturally occurring infection of P. tenuis recorded in a mule deer.

Two years' prospective experience using fluorescence in situ hybridization on uncultured amniotic fluid cells for rapid prenatal diagnosis of common chromosomal aneuploidies

A probe was generated from the YAC clone 831B9 that was suitable for the prenatal detection of trisomy 21 using fluorescence in situ hybridization (FISH). This probe was initially tested on a series of 650 unselected amniotic fluid samples prior to the karyotype being available. 630 were correctly identified as having two copies and 13 samples were correctly scored as having three copies of chromosome 21. Seven samples failed to produce a result. A trial was then initiated, reporting to clinicians the interphase FISH results before cytogenetic analysis had been performed. During the first 18 months of this trial 1504 samples were tested: 1467 were correctly identified as disomic and 35 samples were correctly scored as trisomic for chromosome 21. Two samples failed to produce a result. A chromosome 18 specific probe (LI.84) was employed where there was a relevant clinical indication (181 samples) and 10 samples were correctly scored as having three copies of chromosome 18. Thus, this approach appears to be reliable and is popular with both clinicians and patients due to the speed of the result. However, it does not replace chromosomal analysis on cultured cells, which detected a range of abnormalities besides the trisomies and triploidies detected by FISH.

Mosaic supernumerary ring chromosome 19 identified by comparative genomic hybridisation

We report the use of comparative genomic hybridisation (CGH) to define the origin of a supernumerary ring chromosome which conventional cytogenetic banding and fluorescence in situ hybridisation (FISH) methods had failed to identify. Targeted FISH using whole chromosome 19 library arm and site specific probes then confirmed the CGH results. This study shows the feasibility of using CGH for the identification of supernumerary marker chromosomes, even in fewer than 50% of cells, where no clinical or cytogenetic clues are present.

Most Jacobsen syndrome deletion breakpoints occur distal to FRA11B

Recent studies have identified a (CCG)n repeat in the 5' untranslated region of the CBL2 protooncogene (11q23.3) and have demonstrated that expansion of this repeat causes expression of the folate-sensitive fragile site FRA11B. It has also been demonstrated that FRA11B is the site of breakage in some cases of Jacobsen syndrome (JS) involving terminal deletions of chromosome 11q. We report on 2 patients with JS and a 46,XX,del(11)(q23.3) karyotype. In both cases, microsatellite and fluorescence in situ hybridization analyses indicated that the deletion breakpoint was approximately 1.5-3 Mb telomeric to FRA11B. There was no evidence of expansion of the CBL2 (CCG)n repeat in the parents of either patient. The deleted chromosome was of paternal origin in both cases, although it was of maternal origin in the cases reported to be caused by FRA11B. These findings and those in previously reported patients suggest that the breakpoint for most 11q deletions in JS patients is telomeric to FRA11B, which raises the possibility that there may be other fragile sites in 11q23.3 in addition to FRA11B. These findings also support previous evidence that there may be a propensity for breakpoints to differ depending on the parental origin of the deleted chromosome.

A new strategy for cryptic telomeric translocation screening in patients with idiopathic mental retardation

Cryptic unbalanced chromosome rearrangements in the telomeric bands of human chromosomes constitute a significant cause of "idiopathic" mental retardation. Here, we have described a new strategy based upon comparative genomic hybridisation (CGH) to screen for these abnormalities. A modified CGH analysis showed three unbalanced cryptic rearrangements in five patients from three families. These chromosome abnormalities and their balanced forms in the relatives were then confirmed by fluorescence in situ hybridisation (FISH). This study describes a new approach to the diagnosis of cryptic translocations between the G band negative ends of chromosomes and confirms the significant contribution of cryptic telomeric rearrangements to idiopathic mental retardation.

Locus heterogeneity, anticipation and reduction of the chromosome 2p minimal candidate region in autosomal dominant familial spastic paraplegia

We examined 11 Caucasian pedigrees with autosomal dominant 'uncomplicated' familial spastic paraplegia (SPG) for linkage to the previously identified loci on chromosomes 2p, 14q and 15q. Chromosome 15q was excluded for all families. Five families showed evidence for linkage to chromosome 2p, one to chromosome 14q, and five families remained indeterminate. Homogeneity analysis of combined chromosome 2p and 14q data gave no evidence for a fourth as yet unidentified SPG locus. Recombination events reduced the chromosome 2p minimum candidate region (MCR) to a 3 cM interval between D2S352 and D2S367 and supported the previously reported 7 cM MCR for chromosome 14q. Age of onset (AO) was highly variable, indicating that subtypes of SPG are more appropriately defined on a genetic basis than by AO. Comparison of AO in parent-child pairs was suggestive of anticipation, with a median difference of 9.0 years (p<0.0001).

Identification of variant translocations in chronic myeloid leukemia by fluorescence in situ hybridization

We studied two cases of chronic myeloid leukemia (CML) having variant complex translocations detected by trypsin G-banding and fluorescence in situ hybridization (FISH). Application of dual color- (DC-) FISH using abl and bor cosmid probes permitted us to detect the bor-abl fusion event on both interphase nuclei and metaphase spread. Furthermore, FISH using combinatorial hybridization (centromeric-library and library-library probes) demonstrated the content and the position of the translocations in CML patients with variant (complex type) Ph-positive rearrangements. FISH analysis appears to be superior than conventional cytogenetic analysis.

The inhibition of antigen-induced eosinophilia and bronchoconstriction by CDP840, a novel stereo-selective inhibitor of phosphodiesterase type 4

1. The novel tri-aryl ethane CDP840, is a potent and selective inhibitor of cyclic AMP phosphodiesterase type 4 (PDE 4) extracted from tissues or recombinant PDE 4 isoforms expressed in yeast (IC50S: 4-45 nM). CDP840 is stereo-selective since its S enantiomer (CT 1731) is 10-50 times less active against all forms of PDE 4 tested while both enantiomers are inactive (IC50S: > 100 microM) against PDE types 1, 2, 3 and 5. 2. Oral administration of CDP840 caused a dose-dependent reduction of interleukin-5 (IL-5)-induced pleural eosinophilia in rats (ED50 = 0.03 mg kg-1). The eosinophils in pleural exudates from CDP840-treated animals contained higher levels of eosinophil peroxidase (EPO) than cells from control animals, suggesting a stabilizing effect on eosinophil degranulation. CDP840 was approximately equi-active with the steroid dexamethasone in this model and was 10-100 times more potent than the known PDE 4-selective inhibitors rolipram and RP73401. The activity of CDP840 was not influenced by adrenalectomy, beta-sympathomimetics or beta-sympatholytics. 3. Antigen-induced pulmonary eosinophilia in sensitized guinea-pigs was reduced dose-dependently by CDP840 (0.01-1 mg kg-1, i.p.) and intracellular EPO levels were significantly higher. CDP840 was more potent in these activities than CT1731 or rolipram and comparable in potency to RP73401. 4. Rolipram or CDP840 were less active than dexamethasone in preventing neutrophil accumulation, or exudate formation in carrageenan-induced pleurisy in rats and thus do not exhibit general anti-inflammatory activity. 5. In sensitized guinea-pigs, aerosols of the antigen ovalbumin caused a dose-dependent bronchoconstriction demonstrated by an increase in pulmonary inflation pressure. Administration of CDP840 (0.001-1.0 mg kg-1, i.p.), 1 h before antigen challenge, resulted in dose-dependent reduction in response to antigen. This activity was not due to bronchodilatation since higher doses of CDP840 (3 mg kg-1) did not significantly change the bronchoconstrictor response to histamine. Rolipram was approximately 10 times less active than CDP840 in preventing antigen-induced bronchoconstriction. 6. These results confirm the observations that selective PDE 4 inhibitors reduce antigen-induced bronchoconstriction and pulmonary eosinophilic inflammation. CDP840 is more potent than rolipram in inhibiting native or recombinant PDE 4. Unlike the recently described potent PDE 4 inhibitor RP73401, CDP840 is more active than rolipram in the rat IL-5 model following oral administration. The novel series of tri-aryl ethanes, of which CDP840 is the lead compound, could be the basis of an orally active prophylactic treatment for human asthma.

A practical strategy for detection of major chromosome aneuploidies using ratio-mixing fluorescence in situ hybridization

We describe the use of ratio-mixing FISH to visualize simultaneously probe sets specific for chromosomes 13, 18 and 21 as well as both sex chromosomes in uncultured lymphocytes and amniocytes. This method has the advantage of a smaller sample requirement than uni-colour FISH and potential for analysis of a larger number of chromosome aneuploidies using a minimum number of different probe haptenization and detection systems. An unselected series of uncultured lymphocytes and amniocytes was used to investigate the reliability of ratio-mixing FISH for diagnostic applications. The results indicate that the five-colour ratio-mixing FISH is a reliable technique and can be used for simultaneous detection of major aneuploidies. However, as a diagnostic approach, the strategy of using a three-colour ratio-mixing FISH and a dual colour to detect the five clinically important aneuploidies on two slides from the same sample, appears to be simpler and more practical.

Familial Wolf-Hirschhorn syndrome resulting from a cryptic translocation: a clinical and molecular study

We present three cousins who have normal karyotypes, despite having clinical features of Wolf-Hirschhorn syndrome. Fluorescence in situ hybridisation techniques confirmed that all three relatives were monosomic for the distal short arm of chromosome 4 and that a cryptic translocation involving chromosomes 4 and 11 was segregating within the family. Segregation analysis indicated that the risk of an affected child being born to a parent carrying the translocation was 15%. Molecular analysis showed that loci D4S111 and D4S115 were not deleted in the proband, thus excluding these loci from the "Wolf-Hirschhorn critical region". Surprisingly, DNA studies also suggested that the translocation breakpoint on chromosome 4 was within the region of a preexisting paracentric inversion.

Down syndrome with partial duplication and del (21) syndrome: study protocol and call for collaboration. Study I: Clinical assessment

We report on the clinical and cytogenetic assessment of five cases of Down syndrome phenotype with either a partial duplication of chromosome 21 or a normal karyotype, and we quote a case of del (21q) syndrome. Down syndromes with a partial duplication of chromosome 21 (as well as cases of del (21q), which are partly the phenotypic countertype of trisomy 21) are of paramount importance in the understanding of genes involved in the phenotype of Down syndrome. The goal is to find the relevant genes implicated in the main traits of Down syndrome (i.e. mental retardation, Alzheimer disease, and serious visceral malformations). Such a goal, in our opinion, cannot be reached just by publishing the genotype and the phenotype of a small cohort of patients: 1. a sufficient number of accurate cases is needed, and 2. data have to be computerized for definite conclusions to be reached. The main aims of this report are to present our study protocol and to invite colleagues to participate in a collaborative study in order to collect a maximum of these (rare) cases.

The human 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene cluster on chromosome 1p13 contains a presumptive pseudogene; 3 beta-HSD and CYP17 do not segregate with dominantly inherited hirsutism

Four hirsute females from a family exhibiting idiopathic dominant hirsutism were examined. Basal blood levels of delta 5 and delta 4 steroids were within the normal range, but ACTH stimulation led to increases in 17-hydroxypregnenolone and dehydroepiandrosterone that were significantly above control levels. Using polymorphic genetic markers, the genes for cytochrome P450c1717 encoded by CYP17, and the type I and II forms of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) were found not to segregate with hirsutism in this family, though a base substitution was detected in the 3' end of exon 1 of the gene for 3 beta-HSD type I in three of the four patients investigated. Analysis of PCR patients amplification products by denaturing gradient gel electrophoresis (DGGE) and sequencing revealed a novel homologue of exon 3 of 3 beta-HSD. DNA of one of the affected patients was used to create a genomic library in lambda gem 11 and clones containing the novel homologue were obtained and partially sequenced. The equivalent clone was obtained from a genomic library of an unrelated normal individual. The sequences of the clones from patient and control were identical and homologous to exons 2-4 of human 3 beta-HSD types I and II. No difference was found in the PCR primer sites that flanked the exons 3 homologue which led to its detection on DGGE gels. In both clones, stop codons and deletions were identified in the exon 4 homologue, leading to the deduction that the sequence comes from a pseudogene, which we call 3 beta-HSD psi 1. The pseudogene mapped to chromosome 1p13. It was concluded that dominantly inherited idiopathic hirsutism in this rare kindred was not due to deficiencies in 3 beta-HSD types I, II, or psi or of CYP17).

Diagnosis of ameloblastoma of the maxilla by fine needle aspiration. A case report

Ameloblastoma is a tumor of odontogenic epithelium that occurs in the jaws. We describe a case of an ameloblastoma of the maxilla that was diagnosed by fine needle aspiration cytology. The patient presented with a mass in the left maxillary sinus. Cytologic examination of the aspirate material showed numerous sheets of tightly packed basaloid cells. Several sheets of cells were surrounded by a row of columnar cells, with the nuclei oriented away from the basement membrane (peripheral palisading). Histologic examination of the resection specimen confirmed the presence of an ameloblastoma of the maxilla.

New members of the 3 beta-hydroxysteroid dehydrogenase gene family

Several bands of hydridization are detected when southern blots of human genomic DNA are proved with cDNA of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) type I. Two experimental approaches were adopted to estimate the size of the 3 beta-HSD gene family. Firstly, primer designed to amplify 3 beta-HSD type I and II genes were found on occasion to amplify DNA products of appropriate length but which were resolved as distinct sequences by denaturing gradient gel electrophoresis (DGGE). Five of these novel bands were cloned and their sequences were found to be closely related to 3 beta-HSD types I and II. Secondly, 57 genomic clones were selected from two lambda genomic libraries by hybridization with exonic probes of 3 beta -HSD type I. These were screened for novel members of the gene family by pcr amplification using various combinations of PCR primers to the type I and II genes, particularly those primers that previously amplified novel PCR products from genomic DNA. Amplification products from (lambda) clones were screened for novel sequences by DGGE. As a result of these approaches, at least five new members of the 3 beta-HSD gene family were found, one of which locates to the 3 beta -HSD type I and II gene cluster on 1p13. The existence of additional closely related but distinct members of the gene family should be recognized as a potential complication when screening PCR fragments for mutations in the type I and II genes. DGGE was found to be an exceedingly rapid means of screening amplification products from (lambda) clones to search for novel members of the gene family.

Familial split hand/split foot long bone deficiency does not segregate with markers linked to the SHFD1 locus in 7q21.3-q22.1

Ectrodactyly (split hand/split foot, SHSF) is characterized by the absence of middle rays of the hand or the foot. Cytogenetic analyses of some of the cases have indicated an association between chromosomal rearrangements involving 7q21.3-q22 and ectrodactyly. Based on these observations, an autosomal dominant form of ectrodactyly is assumed to reside in this region and the locus has been designated SHFD1 (split hand/split foot disorder). Here we report a large family where split hand/split foot long bone deficiency (SHFLD) segregates in an autosomal dominant mode. Linkage analysis, using microsatellite markers located in 7q21-q22, excludes this region from containing the gene responsible for SHFLD in this family. These results would appear to indicate genetic heterogeneity exists in autosomal dominant SHSF.

Comparison of biphasic and monophasic waveforms in epicardial atrial defibrillation

OBJECTIVES

Because biphasic waveforms have previously been shown to be more efficient than monophasic waveforms in defibrillation of the ventricle, we compared the efficiency of the two waveforms in defibrillation of the atria.

BACKGROUND

The development of an implantable atrial defibrillator would offer significant advantages over current approaches to the management of atrial fibrillation. Patient tolerance of atrial shocks from such a device, however, would depend critically on the deployment of an efficient waveform.

METHODS

Both the monophasic and biphasic shocks were of 8-ms duration, and the biphasic was a dual-capacitor waveform with equal first- and second-phase duration and leading-edge voltage. One hundred randomized atrial shocks were evaluated in 21 patients during cardiopulmonary bypass. Atrial fibrillation was induced by the application of alternating current. Atrial shocks were delivered through customized, contoured epicardial paddles applied to the posterior left atrial wall (surface area 11 cm2) and to the anterior right atrial wall (surface area 26 cm2).

RESULTS

For the monophasic waveform the delivered energy (joules) associated with 50% success (E50) was 1.44 J (95% confidence interval [CI] 0 to 11.2) and with 80% (E80) success 3.9 J (95% CI 2.42 to 109.8); for the biphasic waveform 50% success was achieved with 0.37 J (95% CI 0.36 to 0.38) (p = NS) and 80% success with 0.57 J (95% CI 0.56 to 0.58) (p < 0.05).

CONCLUSIONS

A biphasic waveform is more efficient than a monophasic waveform in atrial defibrillation. This may have implications for the development of an implantable atrial defibrillator for paroxysmal atrial fibrillation in addition to improvement of elective transthoracic and endocardial cardioversion of chronic atrial fibrillation.

Assignment of the gene encoding the human thyrotropin-releasing hormone receptor to 8q23 by fluorescence in situ hybridization

A cDNA for human thyrotropin-releasing hormone (TRH) receptor has been isolated from a human pituitary cDNA library. By using this cDNA as a biotinylated probe, the gene encoding the TRH receptor has been localized to chromosome 8q23 by in situ hybridization.

Agenesis of the corpus callosum associated with MASA syndrome

MASA syndrome includes mental retardation, adducted thumbs, shuffling gait and aphasia or speech delay. MASA syndrome, X-linked hydrocephalus and X-linked spastic paraplegia have been linked to the same markers on Xq28 and perhaps represent variation in the clinical expression of the same gene or manifestations of different mutant alleles. The present family includes five males in two generations with borderline to mild mental retardation (5/5), speech delay (5/5), spastic paraplegia (5/5), adducted thumbs (2/5) and marked hydrocephalus (1/5). Of these males, four were evaluated by MRI or CT scan and all four were determined to have partial to complete agenesis of the corpus callosum (ACC). DNA studies confirm linkage to Xq28 probe St14 (DXS52) with a lod score of 2.86 and no recombination. It is not known if X-linked ACC is linked to the same Xq28 region.

Regional chromosomal assignment of the Kell blood group locus (KEL) to chromosome 7q33-q35 by fluorescence in situ hybridization: evidence for the polypeptide nature of antigenic variation

The gene encoding the Kell blood group polypeptide has been localized to chromosome 7q33-35 by in situ hybridization using a biotinylated 1.1-kb DNA fragment containing the 3' half of the human cDNA. This assignment is in accord with genetic localization using antigenic variation as a marker, and strongly suggests that Kell antigenic determinants are part of the polypeptide chain rather than the associated sugar molecules.

Regional chromosomal assignment of the human platelet phosphofructokinase gene to 10p15

A cDNA for human platelet 6-phosphofructokinase (PFKP) has been isolated from a human Raji cell line cDNA library. Using this cDNA as a probe, the gene for human PFKP, previously mapped to chromosome 10pter-p11.1, has been further localized to 10p15 by non-isotopic in situ hybridization.

Duplication of distal 19q: clinical report and review

We report on a 20-month-old boy with duplication of the distal part of 19q. His karyotype is 46,XY, -22, + der(22),t(19;22)(q13.3;p11.2)mat. The propositus has multiple minor anomalies, congenital heart defects, seizures, profound psychomotor retardation, and growth impairment. These characteristics are similar to those in the other 10 reported cases of distal 19q duplication and help delineate the phenotype. A review of the literature is presented.

Chromosomal assignment of a large tRNA gene cluster (tRNA(Leu), tRNA(Gln), tRNA(Lys), tRNA(Arg), tRNA(Gly)) to 17p13.1

A cluster of tRNA genes (tRNA(UAGLeu), tRNA(CUGGln), tRNA(UUULys), tRNA(UCUArg)) and an adjacent tRNA(GCCGly) have been assigned to human chromosome 17p12-p13.1 by in situ hybridization using a 4.2 kb human DNA fragment for tRNA(Leu), tRNA(Gln), tRNA(Lys), tRNA(Arg), and, for tRNA(Gly), 1.3 kb and 0.58 kb human DNA fragments containing these genes as probes. This localization was confirmed and refined to 17p13.100-p13.105 using a somatic cell hybrid mapping panel. Preliminary experiments with the biotinylated tRNA Leu, Gln, Lys, Arg probe and metaphase spreads from other great apes suggest the presence of a hybridization site on the long arm of gorilla (Gorilla gorilla) chromosome 19 and the short arm of orangutan (Pongo pygmaeus) chromosome 19 providing further support for homology between HSA17, GGO19 and PPY19.

Analysis of the origin of Turner's syndrome using polymorphic DNA probes

Thirty-four families with a child or fetus with Turner's syndrome were studied using a series of polymorphic DNA probes. Analysis of the origin of the normal X chromosome was possible in all cases. In 16 families with 45,X (four fetuses and 12 livebirths), the observed X was maternal in each case, indicating a preferential loss of the paternal sex chromosome at, or before, conception. In the remaining 18 families with a variety of karyotypes, but especially in those where the child had an isochromosome of Xq or a ring X, there was again a strong tendency for the normal X to be maternal. Analysis of parental ages was performed with known origin of each abnormality, but no evidence for an increased or decreased parental age effect was detected.

Regional chromosomal assignment of the human mineralocorticoid receptor gene to 4q31.1

The gene for human mineralocorticoid receptor (hMR), previously mapped to chromosome 4, has been further localized to 4q31.1 by in situ hybridization using a biotinylated 3.75 kb human cDNA clone encoding the primary amino acid sequence of hMR as a probe. Preliminary comparative mapping studies in orangutan (Pongo pygmaeus) suggest localization of the probe to the long arm of chromosome 3.

Regional assignment of the human C1-inhibitor gene to 11q11-q13.1

In situ hybridisation using a biotinylated 1.8 kb human cDNA clone in both normal and structurally abnormal chromosomes supports regional localisation of the gene for human C1-inhibitor to chromosome 11q11-q13.1.

Genotype-phenotype correlations in XX males and their bearing on current theories of sex determination

Clinical, chromosomal and molecular studies of a group of 15 XX males confirm the presence of two main groups. A Y + ve group of ten patients exhibit sex reversal as the result of transfer of the distal end of the short arm of the Y chromosome, including testis determining factors, to the short arm of one X-chromosome, presumably by accidental crossing-over in paternal meiosis. The ten patients have Klinefelter's syndrome but differ from XXY cases in that they are short and shown no impairment of intelligence. The four Y-ve XX males have no demonstrable Y sequences and differ from Y + ve cases in abnormality of the external genitalia and invariable gynaecomastia; in this, they more closely resemble XX true hermaphrodites than XY males. These observations on Y - ve XX males and an additional exceptional Y + patients suggest that the ZFY locus is not essential for male differentiation and is not the primary testis determining factor. Male sex determination in sporadic, and familial Y-ve XX males and true hermaphrodites is likely to be the result of mutation in an X-linked TDF gene and its consequent escape from the constraints of X-inactivation. It seems premature to abandon the dosage model of sex determination on the recent evidence that ZFX does not show dosage compensation.

Regional chromosomal assignment of the human glucocorticoid receptor gene to 5q31

The gene for the human glucocorticoid receptor, previously mapped to chromosome 5, has been further localised to 5q31 by in situ hybridisation using a biotinylated 4.3-kb cDNA probe.

An aetiological study of isochromosome-X Turner's syndrome

In an attempt to resolve conflicting evidence from the literature concerning the existence of a paternal age effect in 46,X,i(Xq) Turner's syndrome, we have analysed data on all known cases ascertained in the main population centres of Scotland and on others ascertained in England, using population controls matched for year of birth. There was a significant (P = 0.02) increase of 2.3 years in the mean paternal age of the Scottish cases, and a smaller and non-significant increase in their mean maternal age. Logistic regression analysis confirmed that the primary association was with paternal, rather than maternal, age. For the English cases, however, there were small and non-significant decreases in their mean maternal and paternal ages. The differences between the two groups were also significant, but cannot be explained by any likely source of ascertainment bias. We therefore conclude that there is no evidence for a universal paternal age effect in this condition, but that at least one mechanism of origin, occurring with variable frequency, may be associated with increased paternal age. Using data from this and earlier published studies, we estimate the incidence of individuals with a 46,X,i(Xq) cell line to be between 3.3 and 13 per 10(5) female livebirths.

Recurrences of trisomy 18 and trisomy 13 after trisomy 21

Between 40 years and 43 years of age, a woman had three consecutive pregnancies with different prenatally diagnosed autosomal trisomies. This is compatible with the view that the predisposition to non-disjunction is not chromosome-specific.

Detection of a 15q deletion in a child with Angelman syndrome by cytogenetic analysis and flow cytometry

A proximal 15q deletion, del(15) (q11:q13), was detected in a child with Angelman syndrome by cytogenetic analysis of peripheral lymphocytes. The chromosomes of both parents appeared normal. Flow karyotype analysis carried out on lymphoblastoid cell lines derived from the child and her parents confirmed the presence of a de novo 15 deletion. The estimated size of the deleted segment ranged from 6.1-9.5% of chromosome 15 (approximately 6-9.3 million base pairs). The parental origin of the deleted chromosome could not be resolved by flow cytometry, but cytogenetic evidence suggested that it was derived from the smaller chromosome 15 homologue in the mother.

Interstitial deletion of the long arm of chromosome 2 with normal levels of isocitrate dehydrogenase

We report a 16 year old boy with the abnormal karyotype 46,XY,del(2)(q32.2q33.1) who has mental retardation, microcephaly, epilepsy, craniofacial dysmorphism, distinctive scalloped skin pigmentation, and normal levels of isocitrate dehydrogenase.

Isolation of chromosome-21-specific DNA probes and their use in the analysis of nondisjunction in Down syndrome

Thirteen single-copy, chromosome-21-specific DNA probes were isolated from a recombinant library made from flow-sorted chromosome 21 DNA and regionally mapped using a panel of somatic cell hybrids. Five probes mapped in the 21q21-q22.1 region, six to the 21q22.1-qter region, and one to each of the regions 21q22.1-q22.2 and 21q22.3. Two of these probes, one of which maps in the critical region for Down syndrome, have recently been shown to be expressed at high levels in Down syndrome brain tissue (Stefani et al. 1988). Following preliminary screening for restriction fragment length polymorphisms (RFLPs), five polymorphisms were discovered with four of the chromosome 21 DNA probes. A frequent MspI polymorphism detected by one of the probes was used in conjunction with four previously described polymorphic chromosome 21 probes to analyse the origin of nondisjunction in 33 families with a child or fetus with trisomy 21. The parental origin of the additional chromosome 21 was determined in 12 cases: in 9 (75%) of these it was derived from the mother and in the other 3 cases (25%) it was of paternal origin. Cytogenetic analysis of Q-banding heteromorphisms was informative in three of five families tested, and in each case the RFLP results were confirmed. The meiotic stage of nondisjunction was defined with confidence in five families, the results being obtained with pericentromeric RFLP or cytogenetic markers. Recombination between two nondisjoined chromosomes was demonstrated in one family and is consistent with the view that a lack of recombination between chromosome 21 homologues or failure of their conjunction is not the invariable cause of trisomy 21.