Search PubMed⌕ Search

Biomedical subjects

A Chan

Publications and source records attributed to A Chan.

At least 307 records · Page 17Linked to original sources
PubMed1972

Mixed conformations of deoxyribonucleic acid in chromatin: a preliminary report.

We have established empirical limits for the circular dichroism spectra appropriate for aqueous solutions of the B, C, and A forms of calf-thymus DNA and have analyzed DNA conformations in biological structures. The circular dichroism spectrum above 250 nm of purified calf-thymus chromatin can be satisfactorily accounted for as a linear combination of contributions of the B and C reference spectra without invoking higher-order structures such as supercoils. The amount of A contribution, if any, is below the limit of detection (</=4%). The fraction of bases in the B conformation depends on the method of isolation of nucleohistone, and ranges from 30-50%. The B content of a given preparation is increased by addition of a chelating agent and decreased by addition of divalent ions. More radical increases ensue upon protein removal. Nuclease treatment results in a dramatic decrease in B content. The fraction of bases melting out in the lower transitions of the complex melting profile of a given chromatin preparation corresponds to its B content. We propose a model for chromatin structure in which part of the DNA duplex is exposed or accessible to the solvent and is in the B conformation. The remainder of the base pairs and ribophosphate backbone are protected from interaction with the solvent by efficient histone coverage and are in the C conformation. Divalent ions modulate the distribution of bases between these two conformations.

Animals↗
PubMedDate not supplied

Primary hyperparathyroidism in younger and older patients: symptoms and outcome of surgery.

Two-hundred and fifty patients undergoing initial exploration for primary hyperparathyroidism were analyzed for differences in clinical presentation, biochemical status, pathology, and outcome of surgery. In patients less than 60 years of age (younger patients, n = 119) the most common preoperative symptoms and signs were fatigue (40.3%), bone pain (33.6%), renal stones (31.0%), hypertension (27.7%), and psychiatric illness (27.7%). In patients greater than or equal to 60 years of age (older patients, n = 131) the most frequent symptoms and signs were hypertension (46.6%), fatigue (35.1%), bone pain (30.5%), muscle weakness (28.2%), and joint pain (22.9%). Renal stones were 2.6 times more common (p less than 0.001, chi 2) in younger patients and hypertension 1.7 times more common (p less than 0.05, chi 2) in older patients. There was no significant difference in the preoperative and postoperative laboratory values typically associated with primary hyperparathyroidism. Double adenomas were more common in older (9.2%) than in younger patients (2.5%, p less than 0.05, chi 2). Surgical cure was obtained in 98.8% of patients, and after parathyroidectomy 83% of the younger and 82% of the older patients experienced substantial relief of pre-operative symptoms. Specific questioning revealed most patients to be symptomatic and older patients appear to receive the same clinical and metabolic benefits from parathyroidectomy as younger patients.

Adolescent↗
PubMedDate not supplied

Capillary whole blood monitoring of oral anticoagulants in children in outpatient clinics and the home setting.

A whole blood prothrombin time/international normalized ratio (PT/INR) monitor (CoaguChek, Roche Diagnostics Corp., Indianapolis, IN) was assessed in children for its accuracy, reliability, safety, and acceptance by health care personnel and patient's families. The PT/INR values measured by the CoaguChek monitor showed an excellent correlation with PT/INR values measured by the Hospital for Sick Children (HSC) laboratory (r = 0.96) and Hamilton Civic Hospitals Research Centre (HCHRC) laboratory (r = 0.92) in clinic patients and a close correlation with PT/INR values measured by the HSC laboratory (r = 0.76) and HCHRC laboratory (r = 0.74) in patients at home. Reduced correlation in the home setting did not adversely affect clinical management. The whole blood PT/INR monitor is safe and accurate for children requiring oral anticoagulation therapy in either the outpatient clinic or home setting.

Administration, Oral↗
PubMedDate not supplied

Evaluating carotid artery disease. The concordance between pulsed Doppler/spectrum analysis and angiography.

The results of ultrasonic pulsed Doppler duplex scanning with spectral analysis and computer pattern recognition are compared with the results of contrast arteriography in patients screened for extracranial carotid artery disease. The intraangiographer variability (one radiologist reading the same films twice) and the interangiographer variability (two radiologists reading the same film independently) were also studied. To calculate degrees of agreement corrected for chance, the Kappa statistic was computed for all the evaluation methods employed. At the present time, the concordance between spectral analysis and cerebral contrast angiography reaches a Kappa value of 0.682 +/- 0.064. This level of agreement compares favorably with the interangiographer agreement level (K = 0.568 +/- 0.058) and the intraangiographer agreement (K = 0.711 +/- 0.054). The computer pattern recognition program predicted the degree of stenosis by angiography with an agreement of K = 0.721 +/- 0.059. This concordance compares favorably to that observed when the radiologists are compared with themselves and is greater than that reached by two different radiologists. The continuous improvement in precision and accuracy of duplex scanning offers the promise of its usefulness in clinical and epidemiological studies.

Blood Flow Velocity↗
PubMedDate not supplied

Fibre mapping--a case study.

Fibre mapping, more commonly known as one-to-one taping, was developed in Germany approximately twenty years ago. The technique facilitates the distribution of fibres on a surface to be recorded. The impact of this technique on the investigation of serious crime has been reported in the European Fibre Group on several occasions. This paper represents a case study of the application of the technique. It is believed to be the first time that this technique has been successfully applied in the United Kingdom.

Journal Article↗
PubMedDate not supplied

Outcome measure for paediatric rehabilitation: use of the Functional Independence Measure for children (WeeFIM). A pilot study in Chinese children with neurodevelopmental disabilities.

PURPOSE: To study the use of Functional Independence Measure for children (WeeFIM) in monitoring neurorehabilitation programmes for children with neurodevelopmental disabilities. METHODS: The neurorehabilitation team of the Children's Habilitation Institute of the Duchess of Kent Children's Hospital were trained to administer the WeeFIM. The WeeFIM was administered to children with various neuro-developmental impairment groups undergoing neurorehabilitation programmes in the hospital inpatient and also outpatient setting. The WeeFIM was scored on hospital admission and prior to discharge for those admitted for the rehabilitation programme. The WeeFIM profile was then monitored half yearly. The pilot study used WeeFIM in assessing 104 children with different medical disease categories. The disease or impairment categories included very low birth weight babies (n = 44), cerebral palsy (n = 19), Down's syndrome (n = 9), pervasive developmental disorder (n = 11), Duchenne Muscular Dystrophy (n = 18), and others (n = 3). RESULTS: WeeFim could be used to measure disability, monitor progress, enhance communication, measure the effectiveness of treatment, and document the benefits of rehabilitation intervention. It also served as a networking of neurorehabilitation programmes for different impairment categories in a continuum of settings: hospital, community, school and at home. WeeFIM was found to be a quick and reliable functional assessment instrument in this rehabilitation facility. CONCLUSIONS: WeeFIM could be used to assist neurorehabilitation clinicians in the selection of short term realistic goals and long term rehabilitation strategies for children with various neurodevelopmental disabilities, and the subsequent progress of the children could be monitored objectively.

China↗