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Biomedical subjects

S Mason

Publications and source records attributed to S Mason.

At least 19 recordsLinked to original sources
PubMed1999

Molecular studies in 20 submicroscopic neurofibromatosis type 1 gene deletions.

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder characterized by a marked variability in expression. A more severe phenotype is frequently observed in the group of patients carrying a large NF1 deletion. To study the extent of the microdeletion in these NF1 patients, we generated a partial physical map of the NF1 flanking region. We describe seven PACs and three new polymorphic dinucleotide repeats located outside the NF1 gene and analyzed 20 unrelated individuals with an NF1 microdeletion in a collaborative study. We detected one individual with a substantially smaller deletion including only the NF1 gene and its three embedded genes. In the other 19 patients, the deletion extended at least 1 Mb. The parental origin of the deletion was determined in 15 individuals and was maternal in 13 and paternal in two cases. The new molecular tools described here can be used to unequivocally diagnose a possible extragenic extension of an NF1 deletion.

Base Sequence↗
PubMed1999

An international network for evaluating neuroprotective therapy after severe birth asphyxia.

Animal studies have shown great promise in their applicability to potentially neuroprotective therapies for severe birth asphyxia in human babies. It is now necessary to consider a strategy to evaluate some or all of these techniques within the context of human neonatal randomized control trials (RCT). We have set up a pilot study for an international RCT of mature babies with severe asphyxia (defined by an Apgar score of 5 or less at 10 minutes) and have shown that we can recruit from 120 centers in 17 countries an average of three babies a week, which is the required number to undertake a study over a 2-year period with sufficient power to show a significant improvement in outcome. Particular attention must be given in future studies to the size of improvement in outcome required, generalizability of entry criteria, and the appropriate measure of functional outcome in treated babies.

Animals↗
PubMed1999

Amputation prevention by vascular surgery and podiatry collaboration in high-risk diabetic and nondiabetic patients. The Operation Desert Foot experience.

OBJECTIVE: To describe a unique multidisciplinary outpatient intervention for patients at high risk for lower-extremity amputation. RESEARCH DESIGN AND METHODS: Patients with foot ulcers and considered to be high risk for lower-extremity amputation were referred to the High Risk Foot Clinic of Operation Desert Foot at the Carl T. Hayden Veterans Affairs' Medical Center in Phoenix, Arizona, where patients received simultaneous vascular surgery and podiatric triage and treatment. Some 124 patients, consisting of 90 diabetic patients and 34 nondiabetic patients, were initially seen between 1 October 1991 and 30 September 1992 and followed for subsequent rate of lower-extremity amputation. RESULTS: In a mean follow-up period of 55 months (range 3-77), only 18 of 124 patients (15%) required amputation at the level of the thigh or leg. Of the 18 amputees, 17 (94%) had type 2 diabetes. The rate of avoiding limb loss was 86.5% after 3 years and 83% after 5 years or more. Furthermore, of the 15 amputees surviving longer than 2 months, only one (7%) had to undergo amputation of the contralateral limb over the following 12-65 months (mean 35 months). Compared with nondiabetic patients, patients with diabetes had a 7.68 odds ratio for amputation (95% CI 5.63-9.74) (P < 0.01). CONCLUSIONS: A specialized clinic for prevention of lower-extremity amputation is described. Initial and contralateral amputation rates appear to be far lower in this population than in previously published reports for similar populations. Relative to patients without diabetes, patients with diabetes were more than seven times as likely to have a lower-extremity amputation. These data suggest that aggressive collaboration of vascular surgery and podiatry can be effective in preventing lower-extremity amputation in the high-risk population.

Adult↗
PubMed1998

A sequential randomised controlled trial comparing a dry visco-elastic polymer pad and standard operating table mattress in the prevention of post-operative pressure sores.

Four hundred and forty-six general, vascular and gynaecological surgical patients were recruited to a two centre, double triangular sequential randomised controlled trial to compare the post-operative pressure sore incidence in patients positioned on the standard operating table mattress with those positioned on the dry visco-elastic polymer pad (Action Products Inc.). Two hundred and twenty two patients were randomised to the experimental group and 224 to the standard mattress. The main endpoint failure rate (a pressure sore) was found to be 11% (22/205) for patients allocated to the dry visco-elastic polymer pad and 20% (43/211) for patients allocated to the standard operating table mattress. There was a significant reduction in the odds of developing a pressure sore on the dry visco-elastic polymer pad as compared to the standard, [symbol see text] = 0.46 with 95% confidence interval of (0.26, 0.82), P = 0.010. The adjusted point estimates of the probability of developing a pressure sore on the dry visco-elastic polymer pad and the standard operating table mattress were 0.11 and 0.21 respectively.

Aged↗
PubMed1998

The Leeds Dyspepsia Questionnaire: a valid tool for measuring the presence and severity of dyspepsia.

BACKGROUND: There is currently no validated questionnaire that assesses both the presence and severity of dyspepsia. AIM: To develop the Leeds Dyspepsia Questionnaire (LDQ) as a measure of the presence and severity of dyspepsia, and to assess the validity, reliability and responsiveness of this instrument. METHODS: Unselected patients attending either a hospital dyspepsia clinic or a general practice surgery were interviewed by a trained gastroenterologist or a general practitioner on the presence and severity of dyspepsia. This opinion was compared with the results of the nurse-administered LDQ. Test-retest reliability was assessed by the same research nurse re-administering the LDQ 4-7 days after the initial visit in a subgroup of hospital patients. In a further subgroup of patients one researcher interviewed the patients and a second researcher re-administered the LDQ within 30 min to evaluate inter-rater reliability. The responsiveness of the LDQ was measured by repeating it in patients with endoscopically proven peptic ulcer or oesophagitis 1 month after receiving appropriate therapy. RESULTS: The LDQ was administered to 99 general practice and 215 hospital patients. In the GP population 41/98 (42%) had dyspepsia according to the GP and the LDQ had a sensitivity of 80% (95% CI: 65-91%) and a specificity of 79% (95% CI: 66-89%). The weighted kappa statistic for the agreement between the LDQ and the clinician for the severity of dyspepsia was 0.58 in the GP population and 0.49 in hospital patients. The kappa statistic for test-retest reliability was 0.83 in 107 patients. The LDQ had excellent inter-rater reliability with a kappa statistic of 0.90 in 42 patients. The median LDQ score fell from 22.5 (range 9-36) to 4.5 (range 0-27) in 12 patients 1 month after receiving appropriate therapy (Wilcoxon signed rank test, P < 0.0001). CONCLUSION: The LDQ is a valid, reliable and responsive instrument for measuring the presence and severity of dyspepsia.

Adolescent↗
PubMed1998

Field sensitivity of targeted neonatal hearing screening using the Nottingham ABR Screener.

OBJECTIVE: A population of children having bilateral moderate to profound hearing impairment was investigated to find out the number who passed (false negatives) and who failed (true positives) a screening test based on the auditory brain stem response (ABR). DESIGN: This study of the ABR is a parallel report to Lutman, Davis, Fortnum, and Wood (1997), where the transient evoked otoacoustic emission was examined on a similar but not identical population of at-risk neonates. Hearing screening was undertaken in at-risk neonates (targeted screening) at seven hospitals in the UK using the Nottingham ABR Screener. During the period from January 1988 to December 1993, a total of 6983 neonates had been tested. Assessment of audiological records from the participating centers ascertained that 201 children born between January 1988 and December 1993 had hearing threshold levels in both ears of 50 dB or more, averaged over the speech frequencies 0.5, 1, 2, and 4 kHz. Of these, 51 had completed the ABR screening test. Examination of the ABR records, which included both machine and visual scoring, indicated whether they had passed or failed the screening test. RESULTS: Forty-six of the 51 hearing impaired babies failed the neonatal ABR screen either on one or both ears (five false negatives), and 42 failed the test on both ears (nine false negatives). This resulted in field sensitivities of 90% and 82%, respectively. Two cases of suspected progressive hearing loss have been included in the numbers of false negative results. The percentage of babies passing the screen on both ears and subsequently having normal hearing (specificity) is typically 93%. CONCLUSIONS: Neonatal hearing screening in an at-risk population using a highly automated ABR test is a viable and effective tool for identification of hearing impairment. Although the field sensitivity of the test is high, it is unable to identify all babies with a criterion level of hearing loss. There are a number of possible explanations as to the origin of false negative results: configuration of the pure-tone audiogram, a progressive hearing loss, acquired sensorineural or conductive loss, retrocochlear deafness, or an incorrect interpretation of the screening test. Passing a neonatal screening test, therefore, does not exclude the possibility of subsequent hearing impairment and highlights the need for further surveillance.

Auditory Threshold↗
PubMed1998

Anomalous screening outcomes from click-evoked otoacoustic emissions and auditory brainstem response tests.

Transiently evoked otoacoustic emissions (TEOAE) and auditory brainstem response (ABR) tests were used in parallel to screen 862 neonates with risk factors for hearing loss. Seven neonates (0.81%) passed on TEOAE screen yet failed on ABR in one ear (six neonates) or both ears (one neonate). This combination of results has been termed 'anomalous'. Examination of audiometric results obtained on follow-up shows that in one ear of one neonate the result was consistent with the later confirmed audiogram shape. The explanation for the anomalous results in the remaining ears is unclear although neural maturation and the effects of hyperbilirubinaemia are possibilities. There were no instances of progressive or retrocochlear hearing loss identified. None of the seven neonates had better ear hearing loss of > or = 40 dB on long term follow-up.

Acoustic Stimulation↗
PubMed1998

Refsum's disease. A unique case.

Refsum's disease, or heredopathia atactica polyneuritiformis, is a peroxisomal disorder leading to the accumulation of phytanic acid throughout the body. It affects sensory and motor neurons and the skeletal system. Peripheral neuropathy, ataxia, blindness, deafness, and skeletal hyperostosis are significant findings used in the diagnosis of the disease.

Aged↗
PubMed1998

Improved healing with a collagen-alginate dressing in the chemical matricectomy.

A prospective clinical trial was conducted to evaluate the efficacy of a collagen-alginate wound dressing in the postoperative management of chemical matricectomies. The study involved 20 patients and 23 separate procedures. The collagen-alginate-dressing treatment group had an average healing time of 24.4 days, compared with 35.8 days for the control group, which received treatment consisting of soaks and daily dressing changes (P < .05). The authors suggest that using a collagen-alginate wound dressing in the postoperative management of chemical matricectomies will shorten healing time, thus reducing infection rates and increasing patient compliance and satisfaction.

Adolescent↗
PubMed1997

The interaction of synaptic vesicle-associated membrane protein/synaptobrevin with botulinum neurotoxins D and F.

Botulinum neurotoxins type D and F are zinc-endopeptidases with a unique specificity for VAMP/synaptobrevin, an essential component of the exocytosis apparatus. VAMP contains two copies of a nine residue motif, termed V1 and V2, which are determinants of the interaction with tetanus and botulinum B and G neurotoxins. Here, we show that V1 plays a major role in VAMP recognition by botulinum neurotoxins D and F and that V2 is also involved in F binding. Site-directed mutagenesis of V1 and V2 indicates that different residues are the determinants of the VAMP interaction with the two endopeptidases. The study of the VAMP-neurotoxins interaction suggest a pairing of the V1 and V2 segments.

Animals↗
PubMed1997

Role of the casein kinase I isoform, Hrr25, and the cell cycle-regulatory transcription factor, SBF, in the transcriptional response to DNA damage in Saccharomyces cerevisiae.

In the budding yeast, Saccharomyces cerevisiae, DNA damage or ribonucleotide depletion causes the transcriptional induction of an array of genes with known or putative roles in DNA repair. The ATM-like kinase, Mec1, and the serine/threonine protein kinases, Rad53 and Dun1, are required for this transcriptional response. In this paper, we provide evidence suggesting that another kinase, Hrr25, is also involved in the transcriptional response to DNA damage through its interaction with the transcription factor, Swi6. The Swi6 protein interacts with Swi4 to form the SBF complex and with Mbp1 to form the MBF complex. SBF and MBF are required for the G1-specific expression of G1 cyclins and genes required for S-phase. We show that Swi6 associates with and is phosphorylated by Hrr25 in vitro. We find that swi4, swi6, and hrr25 mutants, but not mbp1 mutants, are sensitive to hydroxyurea and the DNA-damaging agent methyl methane-sulfonate and are defective in the transcriptional induction of a subset of DNA damage-inducible genes. Both the sensitivity of swi6 mutants to methyl methanesulfonate and hydroxyurea and the transcriptional defect of hrr25 mutants are rescued by overexpression of SWI4, implicating the SBF complex in the Hrr25/Swi6-dependent response to DNA damage.

Casein Kinase I↗
PubMed1997

Do patients need to fast for a 13C-urea breath test?

OBJECTIVE: The 13C-urea breath test (13C-UBT) is a useful non-invasive method of diagnosing Helicobacter pylori infection. One of its limitations, however, is that patients have to fast for 4 h before testing. We have compared the accuracy of a non-fasting 13C-UBT (NF13C-UBT) with a fasting 13C-UBT (F13C-UBT) test and against a gold standard. DESIGN: An unblinded prospective crossover study. METHODS: H. pylori status was assessed by histology, culture and rapid urease test. Patients were defined as H. pylori positive if two or more tests gave a positive result and negative if all tests were negative. H. pylori status was indeterminate if only one test gave a positive result. Following endoscopy patients had a F13C-UBT and then a further NF13C-UBT up to 14 days later after eating two slices of toast with jam or honey and tea or coffee. RESULTS: Of the 222 patients recruited to the study, 123 were gold standard H. pylori positive and 94 were negative with five patients having indeterminate status. Compared to this gold standard the NF13C-UBT had a 98% sensitivity and 96% specificity and the F13C-UBT had a 96% sensitivity and 97% specificity. The NF13C-UBT and F13C-UBT agreed in 217/222 (98%) cases. CONCLUSION: Relaxation of the fasting state does not reduce the accuracy of the 13C-UBT, making this test more convenient for patients.

Biopsy↗
PubMed1997

Spinal and cutaneous schwannomatosis is a variant form of type 2 neurofibromatosis: a clinical and molecular study.

OBJECTIVE: To delineate the clinical phenotype, molecular basis, and implications for screening in patients and families with multiple schwannomas not generally involving the cranium. METHODS: As part of a United Kingdom clinical and genetic study of type 2 neurofibromatosis (NF2) patients and families with multiple schwannomas who do not fulfil diagnostic criteria for NF2 have been identified. The clinical phenotype was studied in the extended families and molecular analysis was carried out at the NF2 gene locus on chromosome 22. RESULTS: Patterns of inheritance in five families with schwannomatosis are consistent with inheritance of an autosomal dominant gene. The consistency of phenotype, with relative sparing of the cranium, is constant in these families. However, families which initially seem to be indicative of schwannomatosis may develop into classic NF2 as shown by a sixth family. Many of the tumours found in these families were referred to as "neurofibroma" when they were clearly schwannomas. This difference in classification has major implications for the relative risk of each particular type of neurofibromatosis and neuropathological review may be important in some cases. Genetic linkage analysis in the two largest families is entirely consistent with primary involvement of the NF2 gene. CONCLUSIONS: Variant forms of neurofibromatosis have presented a dilemma in classification and determination of recurrence risks in families. Previous reports have suggested that schwannomatosis is a sporadic non-hereditary condition. Patients with multiple schwannomas are likely to have a variant form of NF2 and up to a 50% risk of passing on a gene predisposing to multiple schwannoma.

Adolescent↗