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Biomedical subjects

D Williamson

Publications and source records attributed to D Williamson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Management of double-layered patellae by compression screw fixation.

Tripartite patella is a form of double-layered patella in which the anterior layer is bipartite. It was first described by Büttner in 1925 (1). More recently, an association with multiple epiphyseal dysplasia has been described (2,3). In this article, we describe a case of symptomatic tripartite patella in a 13-year-old child who was subsequently found to have features of multiple epiphyseal dysplasia. Her patellae had an abnormal excursion with a click and a visible jump in the longitudinal line of movement, but no lateral instability. We present a surgical solution not previously described by fusion of the two main components and report an excellent result.

Adolescent↗
PubMed1998

Angiotensinogen cleavage by renin: importance of a structurally constrained N-terminus.

Angiotensinogen, a plasma serpin, functions as a donor of the decapeptide angiotensin I, which is cleaved from the N-terminus by renin. To assess the contribution of the serpin framework to peptide cleavage we produced a chimaeric molecule of alpha1-antitrypsin carrying the angiotensinogen N-terminus and determined the kinetic parameters for angiotensin I release. The Km for plasma angiotensinogen was 18-fold lower than for the chimaeric protein while the catalytic efficiency was four-fold higher. We also show that Cys-18 participates in a disulphide bond and propose that constraints on the N-terminus profoundly affect the interaction with renin.

Amino Acid Sequence↗
PubMed1998

GMDP for psoriasis.

Explore the source record for details and available documents.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1998

Factor V Cambridge: a new mutation (Arg306-->Thr) associated with resistance to activated protein C.

A new factor V mutation associated with resistance to activated protein C and thrombosis (factor V Cambridge, Arg306-->Thr) was found in one patient from a carefully selected group of 17 patients with venous thrombosis and confirmed APC resistance in the absence of the common Gln506 mutation. The Arg306 mutation was also present in a first degree relative who also had APC resistance. Other potential causes of APC resistance, such as a mutation at the Arg679 site and the factor V HR2 haplotype, were excluded. Subsequent screening of 585 patients with venous thromboembolism and 226 blood donors did not show any other individual with this mutation. Factor VThr306 is the first description of a mutation affecting the Arg306 APC cleavage site and is the only mutation, other than factor V Leiden (Arg506-->Gln), that has been found in association with APC resistance. This finding confirms the physiologic importance of the Arg306 APC-cleavage site in the regulation of the prothrombinase complex. It also supports the concept that APC resistance and venous thrombosis can result from a variety of genetic mutations affecting critical sites in the factor V cofactor.

Arginine↗
PubMed1998

Bayesian decision procedures based on logistic regression models for dose-finding studies.

Early-phase clinical trials, conducted to determine the appropriate dose of an experimental drug to take forward to later trials, are considered. The objective is to find the dose associated with some low probability of an adverse event. A Bayesian model is presented, and a decision-theoretic procedure for finding the optimal doses for each of a series of cohorts of subjects is derived. The procedure is flexible and can easily be conducted using standard statistical software. The results of simulations investigating the properties of the procedure are presented.

Bayes Theorem↗
PubMed1997

MR imaging of soft tissues adjacent to orthopaedic hardware: techniques to minimize susceptibility artefact.

This article demonstrates and compares imaging of orthopaedic hardware (fixation plates, screws, Kischner wire and prostheses) using gradient-echo, spin-echo and fast spin-echo sequences. It describes simple techniques which minimize susceptibility artefact induced by these components at magnetic resonance (MR) imaging, allowing visualization of adjacent soft tissues. The article emphasizes the importance of selecting the appropriate imaging plane in order to avoid hardware distortion of slice select gradients, emphasizes the importance of selecting frequency encoding gradient axes in order to orientate the long axis of the artefact away from the tissue of interest and, finally, compares the marked susceptibility artefact observed adjacent to hardware using gradient-echo with the artefact reduction achieved by using fast spin-echo sequences.

Artifacts↗
PubMed1997

Risk of venous thromboembolism associated with a G to A transition at position 20210 in the 3'-untranslated region of the prothrombin gene.

The odds ratio for the FII 20210G/A mutation in 504 patients with venous thromboembolism compared to controls was 2.0 (95% CI 1.0-4.0) and, for factor V Leiden, 5.8 (95% CI 3.3-10.3). 3/504 patients were heterozygous for both mutations. None of the patients had combined natural anticoagulant deficiency and the FII 20210G/A mutation. We conclude that the FII 20210G/A mutation is present in 2.6% of the population and the relative risk of venous thromboembolism in carriers is 2.0.

Factor V↗
PubMed1997

Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL): initial reliability and validity data.

OBJECTIVE: To describe the psychometric properties of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime version (K-SADS-PL) interview, which surveys additional disorders not assessed in prior K-SADS, contains improved probes and anchor points, includes diagnosis-specific impairment ratings, generates DSM-III-R and DSM-IV diagnoses, and divides symptoms surveyed into a screening interview and five diagnostic supplements. METHOD: Subjects were 55 psychiatric outpatients and 11 normal controls (aged 7 through 17 years). Both parents and children were used as informants. Concurrent validity of the screen criteria and the K-SADS-PL diagnoses was assessed against standard self-report scales. Interrater (n = 15) and test-retest (n = 20) reliability data were also collected (mean retest interval: 18 days; range: 2 to 36 days). RESULTS: Rating scale data support the concurrent validity of screens and K-SADS-PL diagnoses. Interrater agreement in scoring screens and diagnoses was high (range: 93% to 100%). Test-retest reliability kappa coefficients were in the excellent range for present and/or lifetime diagnoses of major depression, any bipolar, generalized anxiety, conduct, and oppositional defiant disorder (.77 to 1.00) and in the good range for present diagnoses of posttraumatic stress disorder and attention-deficit hyperactivity disorder (.63 to .67). CONCLUSION: Results suggest the K-SADS-PL generates reliable and valid child psychiatric diagnoses.

Adolescent↗
PubMed1997

Language as a barrier to the acquisition of anatomical knowledge.

The language of instruction for medical students at the University of Hong Kong is English, which is their second language. This presents a potential barrier to their academic learning. We have studied the extent of this problem by looking at the amount of terminology students have to assimilate during their anatomy course and the way in which the terminology is structured and explained (this provides, more generally, an indication of the factual loading to which medical students are exposed). We have also investigated the effect of the quality of students' language skills on their examination results in anatomy class tests and MBBS exams. It was found that students' entrance levels in English correlated well with their final examination results and that the quality and quantity of their English also correlated highly with scores in class tests. On this basis, we conclude that language is one of the most important barriers to students' academic success in the department and that current teaching materials may not be appropriate.

Anatomy↗
PubMed1997

Pain behavior, spouse responsiveness, and marital satisfaction in patients with rheumatoid arthritis.

Although the pain behavior of some diagnostic groups has been shown to be reactive to social influences, the reactivity of pain behavior in a rheumatoid arthritis (RA) population remains an open question. The authors in this article combined laboratory and self-report assessment techniques to examine the extent to which the pain report and behavior of 52 RA patients was susceptible to influence of social factors within the marital unit. The authors' findings suggest that (a) different types of spouse responsiveness (e.g., solicitous, punishing) may be viewed differently by the RA population than more general chronic pain populations; (b) the patient's perception of spouse responsiveness is a significant predictor of the pain behavior, whereas the spouse's perception of these same behaviors is not; and (c) the patient's perception of the spouse's responsive behavior adds significantly to the prediction of pain behavior over a model based on "disease impact" variables alone.

Adult↗
PubMed1997

Mild thalassemia intermedia resulting from a new insertion/frameshift mutation in the beta-globin gene.

Hematological investigation of an antenatal patient led to the identification of a new beta-thalassemia mutation involving the net insertion of eight nucleotides into exon 2 of the beta-globin gene. As a result of the shift in the protein reading frame, this gene codes for an elongated beta-globin chain (159 amino acids) with an abnormal amino acid sequence beyond residue beta 99. There is no evidence of any abnormal hemoglobin in the circulation. The patient has a mild form of beta-thalassemia intermedia with moderate anemia, evidence of iron overload, severe red cell morphological changes, a significant reticulocytosis, and a marked increase in the proportion of fetal hemoglobin.

Adult↗
PubMed1996

Multi-disciplinary clinical study of Smith-Magenis syndrome (deletion 17p11.2)

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly, mental retardation (MCA/MR) syndrome associated with deletion of chromosome 17 band p11.2. As part of a multi-disciplinary clinical, cytogenetic, and molecular approach to SMS, detailed clinical studies including radiographic, neurologic, developmental, ophthalmologic, otolaryngologic, and audiologic evaluations were performed on 27 SMS patients. Significant findings include otolaryngologic abnormalities in 94%, eye abnormalities in 85%, sleep abnormalities (especially reduced REM sleep) in 75%, hearing impairment in 68% (approximately 65% conductive and 35% sensorineural), scoliosis in 65%, brain abnormalities (predominantly ventriculomegaly) in 52%, cardiac abnormalities in at least 37%, renal anomalies (especially duplication of the collecting system) in 35%, low thyroxine levels in 29%, low immunoglobulin levels in 23%, and forearm abnormalities in 16%. The measured IQ ranged between 20-78, most patients falling in the moderate range of mental retardation at 40-54, although several patients scored in the mild or borderline range. The frequency of these many abnormalities in SMS suggests that patients should be evaluated thoroughly for associated complications both at the time of diagnosis and at least annually thereafter.

Abnormalities, Multiple↗
PubMed1996

Tendon shift in hallux valgus: observations at MR imaging.

OBJECTIVE: This study was undertaken to demonstrate a shift in tendon alignment at the first metatarsophalangeal joint in patients with hallux valgus by means of magnetic resonance imaging. DESIGN: Ten normal feet and 20 feet with the hallux valgus deformity conforming to conventional clinical and radiographic criteria were prospectively studied using magnetic resonance imaging. Correlation was made between tendon position at the first metatarsophalangeal joint and the severity of the hallux valgus deformity. RESULTS: There is a significant shift in tendon position at the first metatarsophalangeal joint of patients with hallux valgus. The insertion of the abductor hallucis tendon is markedly plantarward and the flexor and extensor tendons bowstring at the first metatarsophalangeal joint compared with patients without the deformity. The severity of the tendon shift correlates with the hallux valgus angle and clinical severity of the hallux valgus deformity in each case. CONCLUSION: Patients with hallux valgus have a significant tendon shift at the first metatarsophalangeal joint which appears to contribute to development of the deformity.

Case-Control Studies↗