PubMed Health⌕ Search

Biomedical subjects

H M Kingston

Publications and source records attributed to H M Kingston.

At least 19 recordsLinked to original sources
PubMed2003

Speciation of mercury in soil and sediment by selective solvent and acid extraction.

In order to characterize the mercury hazard in soil, a sequential extraction scheme has been developed to classify mercury species based on their environmental mobility and/or toxicity for either routine lab analysis or on-site screening purposes. The alkyl mercury species and soluble inorganic species that contribute to the major portion of potential mercury toxicity in the soil are extracted by an acidic ethanol solution (2% HCl+10% ethanol solution) from soil matrices as "mobile and toxic" species. A High-Performance Liquid Chromatography (HPLC) system coupled with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) detection has been developed to further resolve the species information into soluble inorganic species (Hg(2+)), methylmercury(II) (MeHg(+)) and ethylmercury(II) (EtHg(+)) species. Alternatively, these species can be separated into "soluble inorganic mercury" and "alkyl mercury" sub-categories by Solid-Phase Extraction (SPE). A custom Sulfydryl Cotton Fiber (SCF) material is used as the solid phase medium. Optimization of the SCF SPE technique is discussed. Combined with a direct mercury analyzer (DMA-80), the SCF SPE technique is a promising candidate for on-site screening purposes. Following the ethanol extraction, the inorganic mercury species remaining in soil are further divided into "semi-mobile" and "non-mobile" sub-categories by sequential acid extractions. The "semi-mobile" mercury species include mainly elemental mercury (Hg) and mercury-metal amalgams. The non-mobile mercury species mainly include mercuric sulfide (HgS) and mercurous chloride (Hg(2)Cl(2)).

Chemical Fractionation↗
PubMed2003

A new method to assess mercury emissions: a study of three coal-fired electric-generating power station configurations.

U.S. Environmental Protection Agency (EPA) Method 7473 for the analysis of mercury (Hg) by thermal decomposition, amalgamation, and atomic absorption spectroscopy has proved successful for use in Hg assessment at coal-fired power stations. In an analysis time of approximately 5 min per sample, this instrumental methodology can directly analyze total Hg--with no discrete sample preparation--in the solid matrices associated with a coal-fired power plant, including coal, fly ash, bottom ash, and flue gas desulfurization (FGD) material. This analysis technique was used to investigate Hg capture by coal combustion byproducts (CCBs) in three different coal-fired power plant configurations. Hg capture and associated emissions were estimated by partial mass balance. The station equipped with an FGD system demonstrated 68% capture on FGD material and an emissions estimate of 18% (11 kg/yr) of total Hg input. The power plant equipped with low oxides of nitrogen burners and an electrostatic precipitator (ESP) retained 43% on the fly ash and emitted 57% (51 kg/yr). The station equipped with conventional burners and an ESP retained less than 1% on the fly ash, emitting an estimated 99% (88 kg/yr) of Hg. Estimated Hg emissions demonstrate good agreement with EPA data for the power stations investigated.

Air Pollutants↗
PubMed2002

Development of microwave-assisted drying methods for sample preparation for dried spot micro-X-ray fluorescence analysis.

Although dried spot micro X-ray fluorescence (MXRF) is an effective analytical technique for trace elemental analysis, the sample preparation procedures currently used suffer from a number of drawbacks. These drawbacks include relatively long preparation times, lack of control of the sample preparation environment, and possibility of loss of volatile analytes during the drying process. Microwave-assisted drying offers several advantages for dried spot preparation, including control of the environment and minimized volatility because of the differences between microwave heating and conventional heating. A microwave-assisted drying technique has been evaluated for use in preparing dried spots for trace analysis. Two apparatus designs for microwave drying were constructed and tested using multielement standard solutions, a standard reference material, and a "real-world" semiconductor cleaning solution. Following microwave-assisted drying of these aqueous samples, the residues were redissolved and analyzed by ICPMS. Effective recovery was obtained using the microwave drying methods, demonstrating that the microwave drying apparatus and methods described here may be more efficient alternatives for dried spot sample preparation.

Journal Article↗
PubMed2001

Identification and expression analysis of spastin gene mutations in hereditary spastic paraplegia.

Pure hereditary spastic paraplegia (SPG) type 4 is the most common form of autosomal dominant hereditary SPG, a neurodegenerative disease characterized primarily by hyperreflexia and progressive spasticity of the lower limbs. It is caused by mutations in the gene encoding spastin, a member of the AAA family of ATPases. We have screened the spastin gene for mutations in 15 families consistent with linkage to the spastin gene locus, SPG4, and have identified 11 mutations, 10 of which are novel. Five of the mutations identified are in noninvariant splice-junction sequences. Reverse transcription-PCR analysis of mRNA from patients shows that each of these five mutations results in aberrant splicing. One mutation was found to be "leaky," or partially penetrant; that is, the mutant allele produced both mutant (skipped exon) and wild-type (full-length) transcripts. This phenomenon was reproduced in in vitro splicing experiments, with a minigene splicing-vector construct only in the context of the endogenous splice junctions flanking the splice junctions of the skipped exon. In the absence of endogenous splice junctions, only mutant transcript was detected. The existence of at least one leaky mutation suggests that relatively small differences in the level of wild-type spastin expression can have significant functional consequences. This may account, at least in part, for the wide ranges in age at onset, symptom severity, and rate of symptom progression that have been reported to occur both among and within families with SPG linked to SPG4. In addition, these results suggest caution in the interpretation of data solely obtained with minigene constructs to study the effects of sequence variation on splicing. The lack of full genomic sequence context in these constructs can mask important functional consequences of the mutation.

Adenosine Triphosphatases↗
PubMed1998

Knowledge, views, and experience of 25 women with myotonic dystrophy.

Twenty-five affected women of reproductive age known to the North West Regional Genetics Family Register (NWRGFR) were interviewed. A semistructured questionnaire, completed by the interviewer, was used to assess understanding and experience of the clinical and genetic aspects of myotonic dystrophy (MD) and attitudes to prenatal diagnosis (PND). Characteristic features of MD (muscle weakness and wasting and myotonia) were well known. Knowledge of other features and complications reflected experience. All subjects were aware that MD is inherited, but only 56% (14/25) knew the risk to their own children and subjects tended to overestimate this risk. Anticipation and maternal transmission of congenital myotonic dystrophy (CMD) were often misunderstood. Almost half of the subjects (12/25) perceived themselves to be moderately or severely affected and 40% (10/25) felt that their symptoms restricted daily life. Feelings of devastation, depression, worry about the future, and guilt at the risk of transmission to their children were described. Many subjects (10/25) said that the worst aspect of MD is the risk of transmission to their children. Over half (14/25) said that the risk of transmitting MD had influenced or would influence their own reproduction. Three-quarters of subjects who felt that MD had influenced their reproductive decisions (9/12) chose to limit their family or have no children; only 25% (3/12) requested PND. Subjects felt that the lack of information concerning clinical severity made PND for MD difficult to consider.

Adolescent↗
PubMed1997

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).

Adolescent↗
PubMed1997

Ozone degradation of residual carbon in biological samples using microwave irradiation.

In an attempt to produce complete oxidation of a biological matrix, bovine liver, ozone was investigated as an additional, potentially non-contaminating, oxidizing reagent after nitric acid digestion. Experiments were carried out to determine the decomposition efficiency of residual carbon species, primarily o-, m- and p-nitrobenzoic acids (NBAs), using ozone. The NBAs were degraded by purging sample digests with ozone, while heating the solutions with microwave energy at atmospheric pressure. The effects of the degradation temperature and solution pH on the ozonation of NBAs were determined. Solid phase extraction (C18) was used to extract NBAs from the acid digestate solutions prior to HPLC analysis. Reversed phase HPLC was used to determine NBA concentrations in digest solutions. After 2.5 h of purging ozone at 80 degrees C, 33.65 +/- 3.80% o-NBA degradation, 19.39 +/- 1.74% m-NBA degradation, and 26.47 +/- 3.36% p-NBA degradation were obtained.

Animals↗
PubMed1997

Normal erythrocyte membrane Gs alpha bioactivity in two unrelated patients with acrodysostosis.

Shortening of the tubular bones of the hands and feet with cone shaped epiphyses is known as peripheral dysostosis and is common to several syndromes including acrodysostosis and Albright's hereditary osteodystrophy (AHO). The underlying defect in AHO is known to be a reduction in bioactivity of the alpha subunit of the signal transducing protein, Gs, and heterozygous deactivating mutations have been shown in the Gs alpha gene. Because of additional overlapping clinical and radiological features it has been suggested that acrodysostosis and AHO represent poles of a single diagnostic spectrum. We have measured Gs alpha bioactivity in two unrelated patients with a clinical diagnosis of acrodysostosis and found both to be normal. Mutation analysis of the Gs alpha gene showed no sequence variation in 12 of the 13 exons examined. These results indicate that, at least in a proportion of patients with acrodysostosis, the condition is aetiologically distinct from AHO.

Child, Preschool↗
PubMed1996

Extraction of selected drugs from serum using microwave irradiation.

Microwave irradiation is used as an alternative heating method for extraction over more conventional hot plate methods. We describe a fast, efficient method for the determination of selected drugs in human blood/serum using microwave extraction. The microwave extraction of organic substances requires special instrumentation and the results have been compared with the results from classical liquid/liquid extraction. The present microwave extractions were performed in an 'atmospheric pressure' system. Before irradiation with microwaves, an appropriate solvent mixture was added to the buffered specimen. Lidocaine, methadone, diazepam, nordiazepam, propoxyphene and norpropoxyphene were tested as model substances. The quantitation was performed by GC/NPD. The procedure has been applied successfully to a number of forensic cases. The use of microwaves decreases the time of extraction and the solvent consumption.

Analgesics↗
PubMed1996

Malignant hyperthermia--a large kindred linked to the RYR1 gene.

Malignant hyperthermia susceptibility is genetically heterogeneous. The ryanodine receptor gene on the long arm of chromosome 19 represents an important candidate gene but not all families with malignant hyperthermia demonstrate ryanodine receptor mutations or linkage to this region of 19q. Linkage to chromosome 17 in the region of the adult muscle sodium channel alpha subunit gene has been suggested in some families; others are not linked to either of these loci. For most families the in vitro muscle contracture test remains the only reliable method of predicting susceptibility to malignant hyperthermia. We have performed linkage analysis in a large family group with malignant hyperthermia in which the in vitro muscle contracture test had been carried out using the procedure standardised by the European Malignant Hyperthermia Group. None of the published ryanodine receptor gene mutations associated with malignant hyperthermia susceptibility were detected in affected individuals but linkage to intragenic ryanodine receptor markers strongly suggest that this gene is involved in malignant hyperthermia susceptibility in this family. This enabled accurate predictive testing by DNA analysis in 11 untested subjects at 50% risk.

Calcium Channels↗
PubMed1996

Miller-Dieker syndrome resulting from rearrangement of a familial chromosome 17 inversion detected by fluorescence in situ hybridisation.

We report a case of Miller-Dieker syndrome (MDS) owing to an unbalanced rearrangement of a familial pericentric inversion of chromosome 17 (inv(17) (p13.3q25.1)). In addition to lissencephaly and the facial features of MDS, the affected child had other congenital malformations consistent with distal 17q duplication. Initial cytogenetic analysis failed to show any abnormality and fluorescence in situ hybridisation (FISH) studies confirmed the 17p deletion in the proband and identified the chromosome 17 inversion in his mother. FISH studies were performed in other relatives and enabled first trimester prenatal diagnosis by chorionic villus sampling in a subsequent pregnancy of the proband's mother. These findings underline the value of FISH in the investigation of MDS families.

Abnormalities, Multiple↗
PubMed1995

Confirmation of locus heterogeneity in the pure form of familial spastic paraplegia.

Familial spastic paraplegia (FSP), characterized by progressive spasticity of the lower extremities, is in its "pure" form generally of autosomal dominant inheritance pattern. Hazan et al. [Nat Genet 5:163-167, 1993] reported tight linkage of a large FSP family to the highly polymorphic microsatellite marker D14S269 with z (theta) = 8.49 at theta = 0.00 They further demonstrated evidence for locus heterogeneity when they showed that 2 FSP families were unlinked to this region. We have subsequently studied 4 FSP families (3 American, one British) and excluded the disease locus in these families for approximately 30 cM on either side of D14S269, thereby confirming evidence for locus heterogeneity within the spastic paraplegia diagnostic classification.

Chromosomes, Human, Pair 14↗
PubMed1995

Clinical and hematologic aspects of the X-linked alpha-thalassemia/mental retardation syndrome (ATR-X).

The hallmarks of the X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome are severe psychomotor retardation, minor facial anomalies, genital abnormalities, and an unusual form of alpha-thalassemia. The demonstration of HbH inclusions in red blood cells after incubation with brilliant cresyl blue confirms the diagnosis. We describe 15 previously unreported cases and analyse the phenotypic and hematologic findings in these subjects and compare them with previously published cases. This study demonstrates the consistency of the main characteristics of this syndrome and extends the phenotype. Developmental changes in phenotype, in particular the coarsening of the facial appearance, are illustrated. The hematologic findings are shown to vary widely; in some cases the manifestation of alpha-thalassemia may be subtle and missed without repeated examination.

Abnormalities, Multiple↗
PubMed1993

46,XY/47,XY, + 17p + mosaicism in amniocytes associated with fetal abnormalities despite normal fetal blood karyotype.

46,XY/47,XY, + 17p + mosaicism was found in two primary amniotic fluid cultures (AFCs). Fetal blood karyotype was normal, but ultrasonography revealed Dandy-Walker malformation and bilateral choroid plexus cysts. Following termination of pregnancy, fetal examination revealed post-axial polydactyly and neuroblastoma-in-situ affecting both adrenals in addition to the cerebellar abnormalities. Mosaicism for the aberrant cell line was confirmed in all fetal tissues sampled and in the placenta.

Abnormalities, Multiple↗
PubMed1993

Occurrence of Duchenne dystrophy in Klinefelter's syndrome.

A boy with Duchenne muscular dystrophy and facial dysmorphism in conjunction with Klinefelter's genotype 47XXY is presented; this is an unusual situation with two genetic errors evolving over two generations. Karyotyping should be considered in boys with Duchenne muscular dystrophy who have unusual features.

Child, Preschool↗
PubMed1992

Apparent cleidocranial dysplasia associated with abnormalities of 8q22 in three individuals.

Cleidocranial dysplasia is an autosomal dominant, generalised skeletal disorder characterised by variable clavicular hypoplasia, frontal bossing, multiple Wormian bones, and delayed eruption of the teeth. The gene locus for this syndrome has not yet been assigned. Three individuals with manifestations of cleidocranial dysplasia associated with rearrangements of chromosome 8q22 are described. The evidence presented suggests that the gene for cleidocranial dysplasia may be located on chromosome 8q in humans in a region showing homology to mouse chromosome 3.

Adult↗
PubMed1992

Chondrodysplasia punctata: further evidence of heterogeneity.

We describe a patient with chondrodysplasia punctata. He had stippled epiphyses and coronal clefting of the vertebral bodies. No peroxisomal abnormalities were detected. His facial appearance and X-rays were suggestive of the Sheffield type of chondrodysplasia punctata. This type of chondrodysplasia punctata appears to be a heterogeneous group.

Chondrodysplasia Punctata↗