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Biomedical subjects

A M Dixon

Publications and source records attributed to A M Dixon.

16 recordsLinked to original sources
PubMed2004

Pseudoaneurysm of the breast: case study and review of literature.

This paper describes the B-mode, colour and spectral Doppler appearances of breast pseudoaneurysm - a rare vascular complication of ultrasound-guided needle core biopsy. Previously reported cases of spontaneous and iatrogenic pseudoaneurysm of the breast are reviewed. The significance of this potentially serious complication is discussed with reference to the increasing use of imaging and image guided techniques in the diagnosis of breast disease.

Aneurysm, False↗
PubMed2000

Modified GOESY in the analysis of disaccharide conformation.

One-dimensional nuclear magnetic resonance techniques were applied to the conformational investigation of a disaccharide. More specifically, nuclear Overhauser enhancements (NOEs) of protons on either side of the glycosidic bond have been used to determine the conformation of the disaccharide alpha-l-Rhap-(1 --> 2)-alpha-l-Rhap-OMe. A modified GOESY sequence, incorporating selective excitation and pulsed field gradient enhancement, was developed and used to accurately measure small NOE signals of interest. These experiments were named M-GOESY, for modified GOESY, and the data they provided were used to calculate internuclear distances in the disaccharide molecule. The accuracy of the M-GOESY measurements was enhanced by elimination of indirect effects, or spin diffusion, by selective inversion(s) of either the intermediate magnetization or the source and target magnetization during the mixing time. Results of this study indicate that the alpha-l-Rhap-(1 --> 2)-alpha-l-Rhap-OMe disaccharide molecule exists primarily in one conformation, with the glycosidic torsion angle psi approximately -30 degrees based on past molecular dynamics simulations.

Disaccharides↗
PubMed2000

Higher education: making an informed choice.

Potential students need to make informed choices when undertaking further study. Potential students should access different sorts of information regarding the institution of their choice. Potential students need to be aware of how service needs influence the choices available. Potential students should have a clear idea of what they are aiming for. Potential students should be aware of the differences between similar courses.

Career Choice↗
PubMed1997

Modified pulsed-field gradient NMR experiments for improved selectivity in the measurement of diffusion coefficients in complex mixtures: application to the analysis of the Suwannee River fulvic acid.

To simplify the complex 1H NMR spectrum of a fulvic acid sample and gain structural and molecular size information, spectral editing techniques were used in conjunction with a general PFG NMR pulse sequence. These editing techniques exploit differences in T1 and T2 relaxation times as well as differences in coupling constants. The experiments were initially performed on a model mixture of glutamic acid and ethyl acetate in order to validate the method as a technique for measurement of diffusion coefficients. The editing experiments were then applied to the International Humic Substances Society Suwannee River fulvic acid standard. These editing techniques allowed more selective measurement of diffusion coefficients for broad classes of components within regions of the 1H NMR spectrum of the fulvic acid solution. The average radii of gyration calculated for the Suwannee River fulvic acid sample from the diffusion coefficients are in good agreement with literature values.

Acetates↗
PubMed1994

Exacerbation of post-dural puncture headache after epidural blood patch.

The purpose of this report is to describe a new complication of epidural blood patch for inadvertent dural puncture. A dural tap in an obstetric patient was managed initially with a prophylactic blood patch via the epidural catheter. Despite this, 48 hr later, she developed post-dural puncture headache, neck, and shoulder pain, and was given a second epidural blood patch. This was followed by an immediate and severe exacerbation of her symptoms, which later resolved after the administration of diclofenac. There were no further sequelae. Although severe complications of epidural blood patch are rare, they are alarming. Exacerbation of the original symptoms of post-dural puncture headache caused by, or following, epidural blood patching has not previously been reported.

Adult↗
PubMed1994

An unusual morphine fatality.

A case is presented of a 90-year-old white female who apparently died of natural causes in a nursing home. Subsequent investigation indicated that the decedent had been administered an unauthorized bolus of morphine just prior to her death. The embalmed body was exhumed, an autopsy performed, and specimens were collected for toxicologic analysis. The liver contained 1.5 mg/kg of free morphine as measured by radioimmunoassay. The presence of morphine was confirmed by gas chromatography/mass spectrometry. A review of the literature as well as in-house data collected from narcotic deaths clearly suggest that the morphine measured in this case was consistent with a lethal concentration. The manner of death was homicide.

Aged↗
PubMed1992

Failure of thumbtacks used in control of presacral hemorrhage.

We report a case of failure of thumbtacks used in achieving last-resort hemostasis in a gunshot injury to the presacral venous plexus/sacrum. Four of five thumbtacks used detached. The exact mechanism of failure is not known. To our knowledge, there are no reports of failure of these hemostatic devices in the literature. This finding suggests to us that thumbtack hemostasis is not without complication. It is not known whether injury to internal viscera and organs occurred secondary to the loose thumbtacks. We suggest that surgeons as well as pathologists use caution when exploring pelvic or abdominal cavities following pelvic vascular trauma due to the considerable danger posed by these sharp objects.

Abdominal Injuries↗
PubMed1990

Thiamylal: review of the literature and report of a suicide.

A 28-year-old white male medical student was found hanging by the neck from the bathroom closet of a hotel room. An intravenous infusion line leading from a bottle of thiamylal sodium (an ultrashort-acting barbiturate) was inserted into the antecubital vein of the left arm. Blood was analyzed for alcohol and other volatiles and for acidic, basic, and neutral drugs. Only thiamylal was detected. Thiamylal was quantified by high-performance liquid chromatography with ultraviolet detection, and its presence was confirmed by gas chromatography/mass spectrometry. The tissue distribution of thiamylal was 29 mg/L in blood, 1.4 mg/L in urine, 16 mg/L in bile, 135 mg/kg in liver, 25 mg/kg in kidney, and 0.4 mg in the stomach contents. The uptake and distribution of thiamylal is similar to thiopental. The distribution of the drug in this case was compared to that of other fatalities involving ultrashort-acting barbiturates.

Adult↗
PubMed1989

Bilateral opercular polymicrogyria.

Foix-Chavany-Marie syndrome (FCMS), or faciopharyngoglossomasticatory diplegia, is an uncommon syndrome that can result from vascular or developmental lesions of the anterior opercula bilaterally. We report the first pathological documentation of the developmental form of this disorder. Pathological examination revealed bilateral failure of opercular closure, opercular polymicrogyria, periventricular gray-matter heterotopias, and absence of the septum pellucidum.

Adult↗
PubMed1984

A fatality involving phentermine.

A case is presented where phentermine, a sympathomimetic amine used as an anorectic drug, is believed to have significantly contributed to the death of an individual in whom other drugs were also found. Blood, urine, and tissue concentrations of phentermine are reported and compared to other cases in the literature.

Adult↗
PubMed1982

Safer sedation for ventilated patients. A new application for etomidate.

A technique is described for sedation of ventilated patients. Six patients who underwent major maxillofacial surgery were given low dose infusions of etomidate and fentanyl for postoperative sedation. Measurements of respiratory function were recorded before and during the period of intermittent positive pressure ventilation. Plasma etomidate levels were estimated. After initial stabilisation on almost constant rate of infusion was used to provide a reproducible level of sedation from which the patients were easily aroused. All patients maintained an adequate minute volume when disconnected from the ventilator. All measured and derived respiratory indices remained within normal limits. Patients exhibited amnesia throughout the period of infusion. All patients found this method of sedation pleasant. This technique may be recommended as an alternative to conventional methods of sedation for ventilated patients.

Adolescent↗
PubMed1982

Diagnostic problem in acute myocardial infarction: CK-MB in the absence of abnormally elevated total creatine kinase levels.

Seven hundred twenty-four consecutive patients admitted to a coronary care unit for chest pain underwent comparative evaluation of ECG and lactic dehydrogenase (LDH) and creatine kinase (CK) enzyme and isoenzyme patterns. Of the 724 patients, 419 (58%) had the myocardial component (MB) of CK detected; however, 69 (16%) of the latter had no abnormal elevation of total CK levels. This group with CK-MB but persistently normal total CK levels demonstrated fewer diagnostic QRS changes on ECG (17% vs 54%) and a lower incidence of LDH 1:2 inversion (28% vs 79%) than did the group with CK-MB and abnormally elevated total CK levels. However, no specific level of either total CK or CK-MB could segregate the patients with QRS or LDH level changes, which suggests that persistently normal levels of CK do not exclude the diagnosis of myocardial infarction. Evidence that myocardial necrosis can occur in the absence of an abnormal elevation of total CK levels is confirmed histologically in one patient.

Clinical Enzyme Tests↗
PubMedDate not supplied

Training cleanroom personnel.

PEOPLE: the one resource that all companies have in common. Companies in general, and especially those involved in the clean or aseptic manufacturing environments cannot rely solely on technological innovation to increase quality and productivity. They must optimize their human assets to raise performance levels. Training is a critical factor. The training process is not simply to impart knowledge; but through education and involvement on a personal level, to alter behavior: CULTURE.

Asepsis↗