Biomedical subjects

C Wilkins

Publications and source records attributed to C Wilkins.

7 recordsLinked to original sources

PubMed1994

Comparison of 7 and 8 French guiding catheters for elective PTCA: results of a prospective randomized trial.

A prospective randomized trial was performed to detect technical and clinical differences of 7F compared to 8F guiding catheters (GC) used in elective coronary angioplasty (PTCA). One hundred and fifteen patients undergoing elective PTCA with standard balloon dilatation catheters were randomized to 7F (55 pts) or 8F (58 pts) guiding catheters. The endpoints were primarily coronary artery and peripheral vascular complications; and secondarily, technical details and quantitative and qualitative angiographic quality. There was no difference between 7F or 8F GC for development of coronary or peripheral vascular complications. With 7F GC there was less blood loss (Hct, 3.5 +/- 3.4% vs. 6.5 +/- 9.6%, P = .033), and less contrast medium (160 +/- 88 mL vs. 200 +/- 119 mL, P = .049) used. Angiographic quality was similar, although visualization of lesions in the left anterior descending coronary artery in the left anterior oblique projection was improved with the 8F GC. There is no advantage of 7F GC for the prevention of coronary or peripheral vascular complications, although there was less blood loss and contrast medium used with the 7F systems.

Aged↗

PubMed1992

Matrix-assisted laser desorption/ionization of high-mass molecules by Fourier-transform mass spectrometry.

Following the first demonstrations of high-mass analysis using time-of-flight matrix-assisted laser desorption/ionization (MALDI) techniques by Hillenkamp, Tanaka and their co-workers, there have been significant efforts in a number of laboratories to adapt the new methodology to Fourier-transform mass spectrometry (FTMS). The motivation for this research is obvious. Namely, it would be desirable to couple the unparalleled high mass resolution of FTMS with the extended mass range provided by MALDI, particularly for analysis of polymers and biomolecules. Unfortunately, prior to the present work, attempts to mate FTMS and MALDI have met with limited success. The highest mass matrix-assisted laser-desorption-FTMS result previously obtained appears to be the unpublished low resolution spectrum of bovine insulin recently reported by Russell and co-workers. We, Campana and co-workers, and Hettich and Buchanan have had some success with MALDI-FTMS of biomolecules with masses lower than 3000 Da, including melittin, a variety of lower mass peptides, and oligonucleotides with masses lower than 1800 Da. Furthermore, with the single exception of Campana's report of obtaining mass resolution of 5000 for the molecular ion of melittin, such spectra have not displayed high resolution. Here, we report successful development of MALDI-FTMS, demonstrated with spectra obtained from a variety of high-mass polymer and biomolecule samples, using 355 nm radiation from an excimer-pumped dye laser for desorption/ionization and sinapinic acid as matrix. Some of these spectra are of much higher mass resolution than is possible with current time-of flight mass spectrometers.

Animals↗

PubMed1991

Nitrous oxide sedation causes post-hyperventilation apnoea.

We have studied, in six normal subjects, the effect of nitrous oxide sedation on the ventilatory pattern and oxygen saturation using pulse oximetry (SpO2) after hyperventilation to an end-tidal carbon dioxide partial pressure (PE'CO2) of 3 kPa. This value of PE'CO2 was shown to be less than the apnoeic threshold of all these subjects when their ventilation vs PE'CO2 response curves were plotted. All subjects became apnoeic when told to relax following hyperventilation while breathing 75% nitrous oxide for 90 s. Apnoea was defined as cessation of breathing for 20 s or more. The mean duration of apnoea was 78 s (range 29-130 s). All subjects demonstrated arterial desaturation (mean SpO2 75%, range 44-87%). In contrast, following hyperventilation with air, no apnoea was seen in any subject, although there was some evidence of desaturation (mean SpO2 92.5%, range 88-98%). It was concluded that subjects who are sedated with nitrous oxide behave similarly to those who are anaesthetized rather than to those who were fully conscious, in that they become apnoeic below the apnoeic threshold point. The reduction in SpO2 after hyperventilation was explained almost entirely by apnoea and may explain abnormalities of respiratory control and hypoxaemia in patients recovering from general anaesthesia or sedation accompanied by hypocapnia. This mechanism may be of importance in obstetric patients after breathing Entonox, when apnoea and hypoxaemia may reduce oxygen delivery to the fetus.

Adult↗

PubMed1988

Thrombolytic therapy with tissue plasminogen activator or streptokinase induces transient thrombin activity.

We have determined the plasma level of fibrinopeptide A as a specific index of thrombin activity during the infusion of a thrombolytic agent in patients with acute myocardial infarction. Peripheral venous plasma levels of fibrinopeptide A increased following the initiation of thrombolytic therapy from 2.7 nmol/L to a peak of 13.0 nmol/L at 30 minutes with streptokinase and from 1.1 nmol/L to a peak of 10.7 nmol/L at 90 minutes with tissue plasminogen activator. The amount of fibrinogen converted to fibrin I was determined by integration of the plasma level of fibrinopeptide A over time. The amount of fibrin I formed over the five-hour period from the start of drug infusion was approximately 10 mg/dL in response to either streptokinase or recombinant tissue plasminogen activator. We conclude that activation of coagulation occurs in response to thrombolytic therapy despite heparin administration. This thrombin action, though transient, would be sufficient to cause rethrombosis if localized and incompletely opposed by fibrinolytic activity.

Fibrin↗

PubMed1987

Quantitation of fragment X formation during thrombolytic therapy with streptokinase and tissue plasminogen activator.

We have determined the extent of fragment X formation during thrombolytic therapy by integration over time of the plasma fibrinopeptide B beta 1-42 concentration. This peptide is quantitatively released when fragment X is formed by plasmin action on fibrinogen or fibrin I. In response to streptokinase (SK) and rt-PA, 264 +/- 54 and 95 +/- 12 mg/dl respectively of fibrinogen was converted to fragment X. By immunoblotting, fragment X was demonstrated as early as 5 min after SK and 30 min after rt-PA, and was still evident 24 h after treatment. Patients treated with SK showed extensive further plasmin degradation of fragment X to fragments Y and D. Thus fragment X concentrations tend to be more similar in the two groups than would be expected from the extent of fibrinogen breakdown. Fragment X forms clots, but these have lower tensile strength and are more susceptible to further plasmin lysis than clots of fibrin. Thus the similar bleeding observed in the two treatment groups might be a reflection of their similar plasma fragment X concentrations.

Fibrin Fibrinogen Degradation Products↗

PubMed1984

Translational control during early Dictyostelium development: possible involvement of poly(A) sequences.

A rapid decrease in the translational efficiency of mRNA synthesized during vegetative growth is associated with the initiation of development in Dictyostelium discoideum. In contrast, newly synthesized mRNA associates with polysomes with high efficiency. Discrimination between these two mRNA populations correlates with a rapid shortening of the poly(A) tract on the preexisting mRNA. A model is proposed in which a critical poly(A) length regulates the pattern of protein synthesis by affecting the efficiency with which mRNAs can interact with the translational machinery. The model suggests that transcriptional and translational controls can be coupled by altering the state of adenylation of the preexisting mRNA population. The model allows radical changes in the pattern of protein synthesis without wholesale destruction of preexisting mRNA.

Base Sequence↗

PubMedDate not supplied

Cranial nerve injury from halo traction.

Six of the 70 patients treated with skeletal traction at the Alfred I. duPont Institute exhibited cranial nerve complications. The sixth cranial nerve was most commonly affected by distraction and resulted in weakness in lateral gaze. A combined lesion of the ninth, tenth and twelfth nerves was not an infrequent complication and presented as abnormalities in swallowing, quality of speech, and of tongue movement. It has not been singled out for its significance in the literature but it is potentially the most lethal of the complications. From our review it appears that patients who have had radiation treatment and who have presented with myelomeningocele experience a higher risk of complication in cranial skeletal traction. A definite clinical-pathological correlation could not be made. Frequent monitoring of the patients in skeletal traction is necessary, and prompt recognition of the clinical signs of these complications must be stressed. The complications in the patients of our series subsided upon release of the distraction force.

Abducens Nerve↗