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Biomedical subjects

C A James

Publications and source records attributed to C A James.

At least 37 records · Page 2Linked to original sources
PubMed1998

Antenatally detected urinary tract abnormalities: changing incidence and management.

UNLABELLED: To define the incidence of urinary tract abnormalities detected by antenatal ultrasound and assess changes in postnatal management we conducted a retrospective survey using data bases of the nephro-urology unit, obstetric ultrasound and perinatal pathology departments. The birth population (105,542) of the two Nottingham teaching hospitals between January 1984 and December 1993 was divided into two 5-year cohorts, 1984-1988 and 1989-1993. Detailed fetal scanning at 18-20 weeks gestation was introduced in 1989. During this 10-year period, 201 abnormalities of the urinary tract were noted with a 2:1 male to female ratio. The incidence of abnormalities in the first 5 years was 1 in 964 compared to 1 in 364 in the last 5 years. There was a significant increase in the number detected before 20 weeks gestation (12% in 1984-1988 compared to 62% in 1989-1993). Despite the increased incidence of abnormalities detected, the termination rate remained static between the two 5-year cohorts. Only 3 fetuses had intra-uterine intervention and 173 were live-born. Eight infants subsequently died in association with other major congenital abnormalities. The incidence of transient abnormalities (antenatal dilatation with no abnormality noted on postnatal ultrasound) increased from 6% in 1984-1988 to 18% in the 1989-1993 cohort. A more conservative approach to postnatal management is reflected by 71% of infants having operations between 1984 and 1988 compared to 35% in 1989-1993. CONCLUSION: The advent of detailed fetal scanning at 18-20 weeks gestation has significantly increased the detection rate of urinary tract abnormalities with no significant increase in pregnancy termination rates. The need for antenatal intervention is a rare event and most problems can be managed conservatively both pre- and postnatally.

Abortion, Induced↗
PubMed1998

Effects of a split keyboard design and wrist rest on performance, posture, and comfort.

The purpose of this study was to examine differences in experienced typists' performance, posture, and musculoskeletal pain when using a split, adjustable (SA) computer keyboard and when using a standard flat keyboard. In addition, the use of a wrist rest was examined for performance, posture, and musculoskeletal pain effects. Eighteen participants were exposed to the SA keyboard and a flat keyboard in a laboratory study of text typing for four consecutive hours on five days. The results indicated that after just 2 h of orientation and practice, the participants could perform as well on the SA keyboard as on the flat keyboard. The SA keyboard provided advantages for reduced wrist/hand pronation. There was no difference between the keyboards in the level of musculoskeletal pain reported by participants after typing. However, they reported increased pain in the back, neck, shoulders, and wrists from the beginning to the end of each of the experimental periods for both keyboards.

Adolescent↗
PubMed1997

Snare retrieval of migrated ventriculoatrial shunt.

Among the numerous complications of ventriculoatrial shunting, discontinuity and migration of a catheter fragment into the heart or pulmonary arteries is only rarely encountered. Percutaneous snare retrieval of shunt tubing from the pulmonary arteries is described in a patient presenting with signs of shunt malfunction.

Adult↗
PubMed1997

Magnetic resonance angiography in trauma.

Following blunt or penetrating trauma to the head and neck, a variety of traumatic vascular injuries may occur. Often the clinical presentation of a craniocervical arterial injury is delayed and neuroimaging studies are necessary to evaluate for delayed findings of intracranial infarction or hemorrhage. In this setting, magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) may allow a prompt noninvasive diagnosis of craniocervical vascular injury. MRA may be helpful in selecting those patients requiring conventional angiography and allows a noninvasive follow-up evaluation of arterial injury following institution of therapy.

Arteries↗
PubMed1996

Flow-flash kinetics of O2 binding to cytochrome c oxidase at elevated [O2]: observations using high pressure stopped flow for gaseous reactants.

A high-pressure stopped-flow apparatus developed in our laboratories provides the capability to use dissolved gaseous reactants at elevated concentrations in solution (in equilibrium with gas pressures up to ca. 30 atm) for measurement of reaction kinetics. We have used this apparatus to follow the reaction of dioxygen with bovine cytochrome c oxidase following photolysis of the fully reduced CO ligated enzyme up to a dioxygen concentration of 16 mM. The observed rate dependence on [02] follows saturation kinetics and was fit to a limiting rate of 1.0 X 10(6) s(-1). This value is approximately the same as that for the thermal loss of CO to solution from the transient CuB bound state formed upon photolysis of the heme-CO complex. Implications for the mechanism of O2 binding and reduction by the heme-copper oxidases are discussed.

Animals↗
PubMed1995

Gender affects doxorubicin pharmacokinetics in patients with normal liver biochemistry.

We studied the variability in doxorubicin pharmacokinetics in 27 patients, all of whom had normal liver biochemistry tests. Blood samples were collected after the first cycle of single-agent doxorubicin given as an i.v. bolus and plasma levels were measured by high-performance liquid chromatography (HPLC). The relationship of doxorubicin clearance (dose/AUC) with biochemical tests (AST, bilirubin, alkaline phosphatase, albumin, creatinine) and physical characteristics (age, gender, height, weight, tumour type) was investigated. The 6 men had a significantly higher doxorubicin clearance than did the 21 women (median values, 59 and 27 lh-1 m-2, respectively; P = 0.002). Doxorubicin clearance was significantly lower in patients with breast cancer than in those with other tumours (median values, 26 and 53 lh-1 m-2, respectively; P = 0.0008). The other biochemical and physical parameters did not correlate with doxorubicin clearance. However, in multivariate analysis, gender was the only factor predicting doxorubicin clearance (r2 = 40%). The ratio of the AUCs for doxorubicinol and doxorubicin (R) was higher in the men than in the women (median values, 0.62 and 0.36, respectively; P = 0.03). We conclude that gender may be an important determinant of doxorubicin clearance in patients with normal liver biochemistry.

Adult↗
PubMed1995

MR and CT diagnosis of carotid pseudoaneurysm in children following surgical resection of craniopharyngioma.

We report the cases of two children who underwent CT, MR, MRA and angiography in the diagnosis of postoperative aneurysmal dilatation of the supraclinoid carotid arteries following surgical resection of craniopharyngioma. Craniopharyngiomas are relatively common lesions, accounting for 6-7% of brain tumors in children. They are histologically benign, causing symptoms by their growth within the sella and suprasellar cistern with compression of adjacent structures, especially the pituitary gland, hypothalamus and optic nerves, chiasm, and tracts. Complete surgical resection, particularly of large tumors, is complicated by the fact that the lesions are usually found within the circle of Willis, with displacement and adherence to the adventitia of these vessels [1, 2]. Recent reports in the neurosurgical literature have described aneurysmal dilatation of the supraclinoid internal carotid arteries following aggressive surgical resection of craniopharyngioma [3, 4].

Adolescent↗
PubMed1995

Gastric teratoma with intramural extension.

Gastric teratoma is an extremely rare neoplasm which accounts for less than two percent of all teratomas. Unlike other teratomas, gastric teratomas are all benign and predominantly occur in males. As gastric teratomas generally present as a palpable abdominal mass, more aggressive solid masses of childhood must be excluded. In this case, CT imaging delineates both cystic and fatty components characteristic of teratoma and displays the rare gastric origin of the lesion.

Humans↗
PubMed1995

Altered vertebrobasilar flow in children: angiographic, MR, and MR angiographic findings.

PURPOSE: To characterize the clinical, MR, MR angiographic, and conventional angiographic findings in vertebrobasilar disease in children. METHODS: Eight children with posterior circulation ischemia and infarction had conventional spin-echo MR and MR angiography of the head and neck. Six patients had conventional angiography. RESULTS: Six patients had alteration of vertebral or basilar artery flow void on spin-echo images. MR angiography showed all six cases of angiographically proved vertebrobasilar dissection or occlusion despite overestimating the extent of arterial abnormality in two patients. In two patients the intracranial peripheral branch cutoff shown at angiography was correctly predicted on screening MR angiography. CONCLUSION: Posterior circulation infarction in children is usually secondary to traumatic injury to the vertebrobasilar circulation. MR and MR angiography noninvasively show vertebrobasilar flow disturbances and compare favorably with angiography in documenting dissection or occlusion of the vertebrobasilar circulation. MR angiography may obviate the need for invasive angiography in these children at diagnosis and during follow-up of anticoagulation therapy.

Adolescent↗
PubMed1995

Rectal thiopental sodium for sedation of pediatric patients undergoing MR and other imaging studies.

PURPOSE: To determine the efficacy and safety of rectal thiopental sodium as a sedation agent for pediatric imaging. METHODS: Four hundred sixty-two infants and children were sedated with rectal thiopental sodium for MR, CT, or nuclear imaging in 1992 and 1993. Patients received screening histories and physical examinations before sedation, and parents gave informed consent. Sedated patients were monitored by pulse oximetry and direct observation. Twenty-four-hour telephone follow-up to assess delayed side effects was performed successfully in 325 patients. RESULTS: Examinations were successfully completed in 96% of patients. The average time from drug administration to sedation was 12.2 minutes. The average time from sedation to discharge from radiology was 71.1 minutes. Eleven percent of patients had desaturation below the pulse oximetric baseline easily treated with oxygen and head positioning. Twenty-four-hour telephone follow-up in 325 patients revealed a 34% incidence of minor rectal irritation and diarrhea, sleepiness, nausea and vomiting, or ataxia. CONCLUSIONS: Rectal thiopental sodium is a safe and effective drug for pediatric sedation.

Administration, Rectal↗
PubMed1994

Head and neck MR angiography in pediatric patients: a pictorial essay.

Magnetic resonance (MR) angiography is a new, noninvasive imaging method with well-known uses in adults for the evaluation of carotid disease in the neck and cerebral vasculopathy. MR angiography examinations were prospectively studied in 126 children to evaluate the usefulness of MR angiography of the head and neck in children, as well as to correlate its findings with those of conventional angiography. Eleven patients underwent conventional angiography in addition to MR angiography. MR angiography was performed with commercially available pulse sequences and included two- and three-dimensional time-of-flight and phase-contrast techniques. Indications for MR angiography included evaluation of pathologic conditions (aneurysms and arteriovenous malformations, infarcts, venous sinus thrombosis, brain tumors, and cerebritis), screening examinations in sickle cell disease, and follow-up of extracorporeal membrane oxygenation. MR angiography was found to be a useful, noninvasive diagnostic and screening examination for head and neck and cerebral vascular abnormalities in children and had excellent correlation with conventional angiography.

Adolescent↗
PubMed1993

Improved method to extract and concentrate porphyrins from liver tissue for analysis by high-performance liquid chromatography.

A new method to extract and concentrate porphyrins from liver tissue for analysis by high-performance liquid chromatography is described. Porphyrins were extracted with acetonitrile-hydrochloric acid, concentrated on disposable octadecylsilyl columns, brought to dryness, and reconstituted in 1.2 M hydrochloric acid. Dried porphyrins were stable at -80 degrees C for at least three weeks, and porphyrins reconstituted in hydrochloric acid were stable for at least 20 h. Yields of uro-, heptacarboxyl-, hexacarboxyl-, pentacarboxyl- and coproporphyrin were > or = 90%. The method allows determination of porphyrin concentrations in small (10-100 mg) samples of liver tissue.

Acetonitriles↗
PubMed1993

Ethoxyresorufin-O-deethylase and porphyrin analysis in chicken embryo hepatocyte cultures with a fluorescence multiwell plate reader.

Rapid and sensitive methods for measuring ethoxyresorufin-O-deethylase (EROD) induction and total intracellular porphyrin accumulation in cultured chicken embryo hepatocytes exposed to polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are described. Cells were cultured in 48-well cell culture plates, and EROD assays were carried out directly within the wells. EROD activity and porphyrin concentrations were determined with a computer-operated fluorescence multiwell plate reader. Porphyrin and EROD assays could be carried out on the same plates or on separate plates. The assays allow one to obtain dose-response curves at rates that are approximately 100 times faster than conventional methods.

Animals↗