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Biomedical subjects

D McCrae

Publications and source records attributed to D McCrae.

6 recordsLinked to original sources
PubMed1996

In vivo sequence diversity of the protease of human immunodeficiency virus type 1: presence of protease inhibitor-resistant variants in untreated subjects.

We have evaluated the sequence diversity of the protease human immunodeficiency virus type 1 in vivo. Our analysis of 246 protease coding domain sequences obtained from 12 subjects indicates that amino acid substitutions predicted to give rise to protease inhibitor resistance may be present in patients who have not received protease inhibitors. In addition, we demonstrated that amino acid residues directly involved in enzyme-substrate interactions may be varied in infected individuals. Several of these substitutions occurred in combination either more or less frequently than would be expected if their appearance was independent, suggesting that one substitution may compensate for the effects of another. Taken together, our analysis indicates that the human immunodeficiency virus type 1 protease has flexibility sufficient to vary critical subsites in vivo, thereby retaining enzyme function and viral pathogenicity.

Amino Acid Sequence↗
PubMed1995

Role of ECMO in the treatment of respiratory syncytial virus bronchiolitis: a collaborative report.

AIM: To report the collaborative experience of extracorporeal membrane oxygenation (ECMO) in the treatment of respiratory syncytial virus (RSV) bronchiolitis between April 1989 and January 1995. METHODS: The medical records of patients with confirmed RSV bronchiolitis referred to three centres (Leicester, Glasgow, and Great Ormond Street) were reviewed. RESULTS: Twenty four infants were identified. Seventeen had been born prematurely (gestational range 23-40 weeks, median 30 weeks). Thirteen infants had been mechanically ventilated after birth and seven of these had evidence of bronchopulmonary dysplasia (BPD). The age of onset of RSV infection varied from three to 64 weeks (mean 17.4 weeks, median 12 weeks). Ventilation before ECMO ranged from one to 16 days and oxygenation indices at the time of referral ranged from 21-73 (mean 39). Ribavirin was used in eight of the 24 patients. Sixteen patients received venoarterial and eight veno-venous ECMO. ECMO hours ranged from 32-647 (median 196 hours). One infant died (survival rate 96%). Cranial ultrasound abnormalities were detected in three patients. However, at follow up only one of the 23 survivors had evidence of developmental delay. CONCLUSION: A group of paediatric patients in whom ECMO can be of benefit has been identified. The use of ECMO should be considered when other means of support prove unsuccessful.

Age of Onset↗
PubMed1992

Development of a medical fiber-optic oxygen sensor based on optical absorption change.

A new fiber-optic oxygen sensor has been developed for use in medical applications. The sensor's viologen indicator becomes strongly absorbent after brief UV stimulation, and then returns to the transparent state. The rate of indicator return to transparency is proportional to the local oxygen concentration. Indicator absorbance is monitored with a red LED and receiving photodiode, and absorbance data are processed by a dedicated cpu. The solid-state sensor system has performance comparable to existing oxygen measurement techniques, and may be applicable for both in vitro and in vivo oxygen measurements.

Absorption↗
PubMed1992

Development of a medical fiber-optic pH sensor based on optical absorption.

A new fiber-optic pH sensor system has been developed. The sensor uses an absorbtive indicator compound with a long wave-length absorption peak near 625 nm; change in absorption over the pH range 6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is split into short and long wave-length components with a dichroic mirror; the respective signals are detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In laboratory tests, the sensor system provided resolution of 0.01 pH, accuracy of +/- 0.01 pH, and response time of 30-40 s. Following gamma sterilization, laboratory sensor testing with heparinized human blood yielded excellent agreement (e.g., r = 0.992 for n = 42) with a clinical blood gas analyzer. Excellent sensor performance and low cost, solid-state instrumentation are hallmarks of this sensor-system design.

Absorption↗