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Biomedical subjects

T Mathews

Publications and source records attributed to T Mathews.

At least 19 recordsLinked to original sources
PubMed2002

Cadasil: presenting as a mood disorder.

CADASIL is an autosomal dominant non-atherosclerotic vasculopathy that frequently presents as recurrent subcortical strokes, or vascular dementia in middle age. Some patients may have prominent mental symptoms or migraine. Widespread white matter demyelination and subcortical lacunar infarcts are demonstrated by magnetic resonance imaging. Demonstration of granular osmophilic material in arteries in skin biopsies is a useful diagnostic tool. CADASIL has been linked to mutation in the Notch 3 gene locus on chromosome 19. Genetic testing is available for clinical diagnosis.

Dementia, Multi-Infarct↗
PubMed1999

The current status of tardive dystonia.

Tardive dystonia (TDt), a persistent dystonia associated with exposure to neuroleptic drugs, is an uncommon disorder. It differs from tardive dyskinesia (TDk) in epidemiology, clinical features, risk factors, pathophysiology, course, prognosis, and treatment outcome. TDt seems to develop faster and is more painful, distressing, and disabling than tardive dyskinesia. In this article, evidence is reviewed on the face, descriptive, construct, and predictive validity of this iatrogenic complication of antipsychotic drugs. It is suggested that TDt should not be lumped together with TDk. It deserves a separate nosological status as an independent diagnostic category. The subclassification of TDt into various subtypes based on coexistence of other movement disorders is suggested.

Adult↗
PubMed1999

Reduce the risk of cot death guidelines. The effect of a revised intervention programme. National Sudden Infant Death Register, Dublin.

In March 1992 the 'Reduce the Risk of Cot Death' guidelines were launched in the Republic of Ireland. In response to epidemiological surveys conducted in 1993 and 1994 these guidelines were revised in November 1995 and a new leaflet was distributed. The study set out to compare parents interviewed in 1994 (n = 153) and 1996 (n = 132) to determine their source of information on the guidelines and the extent of parental change in infant care practice as recommended in these guidelines. In both time periods the media was the most frequent source of information with 63% (n = 97) of respondents having received advice from the media in 1994 compared to 55% (n = 72) in 1996. However a significant number of parents especially young (64%) and new (58%) mothers were uninterested or unable to access the relevant health care literature indicating a group needing a tailored educational package in the future. Medical sources especially Public Health Nurses ranked second in delivering information at 47% (n = 72) in 1994 vs 46% (n = 60) in 1996 while other sources such as family and friends were the least frequent sources of information. In 1996 more respondents (59%; n = 78) put their children to sleep on their back than in 1994 (35%; n = 54) but they used heat more frequently at night [73% (n = 96) in 1996 vs 57% (n = 87) in 1994]. There was no significant difference in the percentage of parents smoking [29% (n = 45) vs 33% (n = 43)], the uptake of breast feeding [40% (n = 61) vs 49% (n = 64)] and the way parents clothed their children [60% (n = 92) vs 58% (n = 77) used more than ten tog] between 1994 and 1996. Although in 1996 the message to reduce the risks of cot death was more specific and direct, it seems to have had less effect on further changing parents' practices. However, the overall effect of the two education programmes has been successful in yielding a low percentage (2%; n = 2) of babies sleeping prone in 1996). Smoking remains the major modifiable risk factor for SIDS in Ireland.

Humans↗
PubMed1999

Gait characteristics of individuals with multiple sclerosis before and after a 6-month aerobic training program.

Individuals who have multiple sclerosis (MS) typically experience problems with physical activities such as walking, resulting from the combined effects of skeletal muscle weakness, sensory disturbances, spasticity, gait ataxia, and reduction in aerobic capacity. The aim of this study was to determine whether a 6-mo exercise program designed for aerobic conditioning might also affect gait abnormalities in individuals with MS. Subjects included 18 individuals with MS who presented a range of disability. Passive range of motion (PROM) in the lower limbs was measured and gait analyzed before and after exercise conditioning. Three-dimensional kinematics, ground reaction forces (GRF), and electromyographic information were acquired as subjects walked at self-selected velocities. Hip PROM increased following conditioning. Mean walking velocity, cadence, and posterior shear GRF (push-off force) decreased. During walking, maximum ankle dorsiflexion decreased and ankle plantarflexion increased. Total knee flexion/extension range during the walking cycle decreased slightly as did maximum hip extension. Results suggest this 6-mo training program had minimal effect on gait abnormalities.

Activities of Daily Living↗
PubMed1996

Molecular characterization of 21p- variant chromosome.

Fortuitously, within a 1-month period, we were referred two individuals for routine cytogenetic amniocenteses involving one chromosome 21 from each patient, which had apparently lost the entire short arm and a major portion of the centromeric alphoid sequences in their amniocytes. Breakage may have occurred within alphoid sequences resulting in extreme variants. Variations of a similar nature were originally referred to as Christchurch (Ch1) chromosomes and have been wrongly determined to be abnormal. The 21p- chromosome variants were similar in both cases, though they are from unrelated individuals. These rare variants, whose origins were both maternal and have no clinical consequences, were characterized by the FISH-technique to provide a greater degree of certainty.

Amniocentesis↗
PubMed1996

Centromeric alphoid sequences are breakage prone resulting in pericentromeric inversion heteromorphism of qh region of chromosome 1.

Structural variations in the pericentromeric region of chromosome 1 are considered the norm. We characterized a chromosome 1 with an inversion by FISH-technique and suggested that the origin of pericentromeric heteromorphism is far more complex than previously suggested. It is postulated that similar to the centromeric alphoid DNA sequences of chromosome 9, chromosome 1 also possesses a "breakage prone" centromeric domain which may be a possible cause of such inversions involving the secondary constriction region.

Adult↗
PubMed1995

Animal model of spinal cord infarction induced by cholesterol embolization.

Though several animal models of ischemic brain infarction have been developed, no animal model of purely ischemic spinal cord infarction exists. In humans, such paralysis often occurs as a complication of aortic surgery. While working on an animal model of cholesterol embolic renal disease, the authors produced an animal model of ischemic spinal paralysis by direct intraaortic injection of cholesterol suspension. With histologic examination of spinal cords of the paralyzed rats, prominent cholesterol crystals were found obliterating the lumen of the anterior and/or posterior spinal arteries. Spinal cord infarction was seen most prominently in the lateral columns and anterior horns, though other areas also were affected. Permanent paraplegia developed in most rats, but transient paralysis developed in a few, followed by partial or full recovery. This model of spinal infarction in nonanesthetized rats can be used to study the pathophysiology and therapy of spinal infarction.

Animals↗
PubMed1994

In situ nick translation of human chromosomes with the restriction endonuclease Pvu II [5' CAG decreases CTG 3'].

The treatment of fixed human chromosomes by a number of restriction endonucleases has opened additional avenues towards understanding the mechanism(s) of chromosome banding. Metaphase chromosomes from five unrelated individuals were treated with restriction endonuclease Pvu II [CAG decreases CTG] which has a 6 bp recognition site. The banding patterns were compared with another restriction endonuclease Alu I [AG decreases CT] which recognizes only 4 bp but the recognition sequences are identical. The results demonstrate that the banding pattern of human chromosomes observed by Pvu II digestion are apparently identical to those observed by Alu I. The mechanisms of chromosomal banding are discussed.

Chromosome Banding↗
PubMed1993

Fine needle aspiration biopsy cytology of chondrosarcoma.

The cytomorphological appearances of bone and soft tissue tumours, when combined with radiology and clinical presentation, can lead to a positive diagnosis in the majority of cases. Our experience with fine needle aspiration biopsy of 13 cases of chondrosarcoma, encountered over a four year period is presented, in correlation with their radiological appearances. It is concluded that. FNAB is a valuable pre-operative tool in characterising chondroid neoplasms in soft tissue and bone.

Biopsy, Needle↗
PubMed1993

Molecular topography of the secondary constriction region (qh) of human chromosome 9 with an unusual euchromatic band.

Heterochromatin confined to pericentromeric (c) and secondary constriction (qh) regions plays a major role in morphological variation of chromosome 9, because of its size and affinity for pericentric inversion. Consequently, pairing at pachytene may lead to some disturbances between homologous chromosomes having such extreme variations and may result in abnormalities involving bands adjacent to the qh region. We encountered such a case, where a G-positive band has originated de novo, suggesting a maternal origin from the chromosome 9 that has had a complete pericentric inversion. In previously reported cases, the presence of an extra G-positive band within the 9qh region has been familial, and in the majority of those cases it was not associated with any clinical consequences. Therefore, this anomaly has been referred to as a "rare" variant. The qh region consists of a mixture of various tandemly repeated DNA sequences, and routine banding techniques have failed to characterize the origin of this extra genetic material. By the chromosome in situ suppression hybridization technique using whole chromosome paint, the probe annealed with the extra G-band, suggesting a euchromatic origin from chromosome 9, presumably band p12. By the fluorescence in situ hybridization technique using alpha- and beta-satellite probes, the dicentric nature was further revealed, supporting the concept of unequal crossing-over during maternal meiosis I, which could account for a duplication of the h region. The G-positive band most likely became genetically inert when it was sandwiched between two blocks of heterochromatin, resulting in a phenotypically normal child. Therefore, an earlier hypothesis, suggesting its origin from heterochromatin through so-called euchromatinization, is refuted here.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Evolution of pericentromeric heterochromatin of human X chromosome.

An unusual large heterochromatic segment around the pericentromeric region of the X-chromosome is reported. In normal circumstances, the pericentromeric region of the X-chromosome is negative by the restriction endonuclease AluI/Giemsa technique. However, this unusual X-chromosome was found to have AluI resistant (positive) chromatin. The evolution of extra heterochromatin is a postzygotic event as substantiated by the presence of a normal cell line.

Biological Evolution↗
PubMed1992

Prenatal cytogenetic diagnosis of 1,400 consecutive amniocenteses.

We report on the incidence of chromosomal abnormalities in 1,400 amniocenteses. Thirty-one cases (2.21%) were found to have various types of chromosomal abnormality. The majority of abnormal cases (54.84%) were trisomies. All individuals with trisomic fetuses chose to terminate the pregnancy with the exception of one who gave birth to a Down's syndrome child. However, fetuses with apparently balanced translocations were phenotypically normal at birth.

Amniocentesis↗
PubMed1992

Molecular characterization of the secondary constriction region (qh) of human chromosome 9 with pericentric inversion.

Pericentric inversion of the secondary constriction region (qh) of human chromosome 9 is a frequent occurrence. This structural alteration is regarded as a normal familial variant, termed heteromorphism, and is inherited in a Mendelian fashion without any apparent phenotypic consequences. We characterized the qh region of chromosome 9 from five individuals using a series of molecular cytogenetic techniques. Four out of the five individuals have an additional area composed of alphoid DNA sequences on the inverted chromosome 9 while one case was found to have an apparently intact alphoid DNA sequence. Although the direct function(s) of alphoid DNA sequences remain unclear, the centromeric breakage involving these sequences in inverted chromosome 9 raises a series of questions pertaining to the monocentric, dicentric and pseudodicentric nature of pericentric inversions. Nevertheless, these findings have prompted us to suggest that the structural organization of alphoid DNA sequences of the centromeric region of chromosome 9 are apparently "breakage prone" and may be associated with a higher incidence of pericentric inversions. Furthermore, the hierarchical organization of various satellite DNA families (alpha-satellite, beta-satellite and satellite III) within the primary and secondary constriction regions of chromosomes 9 are elucidated here.

Adult↗
PubMed1992

Metabolic and hemodynamic responses to concurrent voluntary arm crank and electrical stimulation leg cycle exercise in quadriplegics.

This study determined the metabolic and hemodynamic responses in eight spinal cord injured (SCI) quadriplegics (C5-C8/T1) performing subpeak arm crank exercise (ACE) alone, subpeak functional electrical stimulation leg cycle exercise (FES-LCE) alone, and subpeak FES-LCE concurrent with subpeak ACE (hybrid exercise). Subjects completed 10 minutes of each exercise mode during which steady-state oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), arteriovenous oxygen difference (a-v O2 diff), and total peripheral resistance (TPR) were determined. Although mean VO2 for both ACE alone and FES-LCE alone was matched at 0.66 l/mi, individualized power outputs ranged from 0-30 W (mean = 19.4 +/- 1.3) and 0-12.2 W (mean = 2.3 +/- 0.6), respectively. Hybrid exercise elicited significantly higher VO2 (by 54 percent), VE (by 39-53 percent), HR (by 19-33 percent), and CO (by 33-47 percent), and significantly lower TPR (by 21-34 percent) than ACE or FES-LCE performed alone (P less than or equal to 0.05). Stroke volume was similar between hybrid exercise and FES-LCE alone, and these two exercise modes evoked a significantly higher SV (by 41-56 percent) than during ACE alone. These data clearly demonstrate that hybrid exercise creates a higher aerobic metabolic demand and cardiac-volume load in SCI quadriplegics than either subpeak levels of ACE or FES-LCE performed separately. Therefore, hybrid exercise may provide more advantageous central cardiovascular training effects in quadriplegics than either ACE or FES-LCE alone.

Adult↗