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Biomedical subjects

D R James

Publications and source records attributed to D R James.

At least 55 records · Page 3Linked to original sources
PubMed1985

Fluorescence lifetime quenching and anisotropy studies of ribonuclease T1.

The time-resolved fluorescence of the lone tryptophanyl residue of ribonuclease T1 was investigated by using a mode-locked, frequency-doubled picosecond dye laser. The fluorescence decay could be characterized by a single exponential function with a lifetime of 3.9 ns. The fluorescence was readily quenched by uncharged solutes but was unaffected by iodide ion. These observations are interpreted in terms of the electrostatic properties of the amino acid residues at the active site of the protein, which would appear to restrict the access of solute species to the tryptophanyl residue. The temperature dependence of the fluorescence lifetime and anisotropy decay time could be rationalized in terms of a model which postulates a significant ordering of the solvent layer immediately surrounding the surface of the protein.

Endoribonucleases↗
PubMed1985

Three dimensional digitization of the face and skull.

The possibility of using computer-aided design as a tool for the planning and simulation of facial reconstruction surgery is discussed and has been shown to be feasible. Methods of acquiring the essential measurements on the facial surface and the underlying bone structure in a computer-compatible form are described, including a new approach which has been implemented using a system of fanned laser beams and a television camera for data acquisition. A mathematical analysis of the properties of this kind of imaging system is given. Finally the requirements of a complete aid to surgery system based on this approach are outlined and plans for the implementation of such a system are described.

Computers↗
PubMed1984

An investigation of a group of 35 consecutive patients with a first arch syndrome.

Thirty-five consecutive patients with a first arch syndrome were divided into right and left sided and bilateral groups and were investigated clinically, radiographically and electromyographically. The patterns of muscle activity in the inter occlusal position were significantly different in each of the groups. The morphology of the jaw was related to the muscle activity. The implications of the findings are discussed.

Adolescent↗
PubMed1984

Interference in colorimetric reactions for measuring hydrogen peroxide.

We describe evidence that serum samples from patients with chronic renal failure possess a constituent that interferes with the measurement of uric acid when using a method employing uricase with peroxidase-assisted detection of the hydrogen peroxide generated. The interference is also reflected in reduced recovery of both hydrogen and sarcosine when added to serum from patients with chronic renal failure. The interferent may be protein in nature or protein bound, as the poor recovery of hydrogen peroxide is seen in patients' serum before and after haemodialysis.

Catalase↗
PubMed1984

Problems associated with the measurement of uric acid using two enzyme-mediated reaction systems.

We describe the problems encountered with the adaptation of two enzymatic assays for uric acid to a centrifugal analyser. A method employing the uricase/catalase/aldehyde dehydrogenase enzyme system sometimes suffered from interference due to light-scattering species in samples and reagents. The second method employing the uricase/peroxidase system gave results that were lower than the comparison method.

Acetates↗
PubMed1983

Autogenous rib grafts in maxillofacial surgery.

A review of 41 patients in whom rib grafts were used has shown that this is a relatively simple, reliable and safe procedure for obtaining autogenous bone. The incidence of pneumothorax was significantly lower than that previously reported.

Adolescent↗
PubMed1979

Crystalloid vs. colloid resuscitation: is one better? A randomized clinical study.

The effects of hemodynamic resuscitation with protein-containing or balanced salt solution were studied prospectively in 29 patients undergoing abdominal aortic surgery. Blood loss was replaced with packed red cells and extracellular volume with either Ringer's Lactate (RL) or 5% albumin in Ringer's lactate (ALB). Fluids were given to maintain the pulmonary capillary wedge pressure (PCWP) equal to or within 5 torr above preoperative (PO) levels, the cardiac output (CO) equal to or greater than preoperative values, and the urine output at least 50 ml/hr. Serum colloid osmotic pressure (COP), CO, PCWP, the gradient between COP and PCWP (COP-PCWP), and intrapulmonary shunt (Qs/Qt) were measured PO, intraoperatively (IO), and daily for 3 days. The measured variables were similar PO in both groups. Operation time, estimated blood loss, and transfusions were similar. Total fluids received for resuscitation (day of operation) was 11.3 +/- 0.8 liters (RL) and 6.2 +/- 0.4 liters (ALB). Fluid balance at the end of resuscitation was 8.4 +/- 0.8 liters (RL) and 3.4 +/- 0.5 liters (ALB). Maximum decrease in COP was 40% (P less than 0.001) in the RL group and was insignificant in the ALB group. The COP-PCWP decreased from 11 +/- 1 to 2 +/- 1 in RL (P less than 0.001) and insignificantly in ALB. Qs/Qt increased slightly in both groups following operation but was not different between groups. Fluid balance, total fluid infused, sodium balance, total sodium infused, COP, or COP-PCWP did not significantly correlate with Qs/Qt. Two patients in the ALB group experienced pulmonary edema associated with normal COPs and elevated PCWPs. There were no cases of pulmonary edema associated with low COPs and normal PCWPs in the crystalloid group. These data seriously question the necessity to maintain COP by using protein-containing solutions during acute hemodynamic resuscitation. When titrated to physiological end points, even large volumes of balanced salt solutions are tolerated well.

Albumins↗
PubMed1978

Central venous pressure or pulmonary capillary wedge pressure as the determinant of fluid replacement in aortic surgery.

Both central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) have been used as guides to fluid replacement in patients undergoing abdominal aortic surgery. To test the hypothesis that changes in PCWP (deltaPCWP) may be reliably estimated from changes in CVP (deltaCVP), 55 patients had simultaneous measurements (302 paired observations) of CVP and PCWP, as well as of cardiac output, before and during operation. The correlation between deltaCVP and deltaPCWP was high (r = 0.716, P less than 0.001). The estimated slope for the linear regression was 0.88. The standard error of the estimate was +/- 3.75 torr, making the prediction of deltaPCWP from deltaCVP accurate only to within 7.5 torr. There were five patients who each had a low and failing CVP accompanied by a stable cardiac output and a rising PCWP; for them, a decision to administer fluid based on the CVP might have resulted in pulmonary edema. Although deltaCVP accurately predicted direction and magnitude of deltaPCWP in the majority of patients (90%), there was a small group in whom there was no substitute for direct measurement of PCWP.

Adult↗
PubMed1977

Subtraction technique in intravenous aortography.

Excretory urography using the subtraction technique (100 ml of 60% urographic media injected in 10-12 seconds) demonstrated the aorta and its major branches well enough to prove useful clinically. The method is fast and graphic, and risk seems no greater than that associated with the standard urographic examination.

Aorta, Abdominal↗
PubMed1976

Atrophy of the mandible: reconstruction following fracture.

A rational approach to the management of spontaneous fracture of the severely atrophie mandible is illustrated by means of a case report. A study of the literature reveals that some confusion exists concerning the terms "atrophy" and "osteolysis", and an attempt is made to distinguish between them.

Atrophy↗