Biomedical subjects

A J Petersen

Publications and source records attributed to A J Petersen.

8 recordsLinked to original sources

PubMed2004

Sevoflurane-induced malignant hyperthermia during cardiopulmonary bypass and moderate hypothermia.

A 56-year old man was admitted for elective mitral valve repair and coronary artery bypass surgery due to mitral valve leakage and unstable angina. After induction of anaesthesia he developed a combined metabolic and respiratory acidosis. Different diagnosis were considered and we decided to treat the patient with dantrolene due to suspicion of malignant hyperthermia (MH). The patient received one dose of dantrolene 2,5 mg/kg during cardiopulmonary bypass (CPB) and a second dose of dantrolene 2,5 mg/kg during weaning from CPB. The first arterial blood gas sample taken in the intensive care unit showed relapse of the acidosis and we administered an infusion of 150 mg dantrolene over 3 hours. The patient gradually recovered without sequel and MH was verified by muscle biopsy testing.

Anesthetics, Inhalation↗

PubMed1999

Fish bones at the cricopharyngeus: a comparison of plain-film radiology and computed tomography.

OBJECTIVES: To compare and contrast the use of plain film radiology and computed tomography (CT) scanning in the detection of fish bones at the level of the cricopharyngeus. STUDY DESIGN: Prospective study of 30 different fish bones placed at the level of the cricopharyngeus in a fresh human cadaver head and neck specimen and imaged using both plain films and CT scans. METHODS: Thirty different bones from 10 different local species of fish were selected and grouped as small, medium, or large in size. Both plain-film and CT images of the bones were reported by a radiologist as A, easily seen; B, seen on close inspection; or C, not seen. Results were analyzed using McNemar's test. RESULTS: CT scanning was superior to plain-film radiology in demonstrating the presence of fish bones at the level of the cricopharyngeus (P < .0001, McNemar's test, df = 1 when comparing report type A with B and C). CONCLUSION: The superior usefulness of CT scans in demonstrating the presence of fish bones lodged at the cricopharyngeus has been clearly shown in this study; therefore we advocated its use in selected cases.

Adult↗

PubMed1996

Nucleoside transporters, bcl-2 and apoptosis in CLL cells exposed to nucleoside analogues in vitro.

The purine nucleoside analogues fludarabine (F1) and chlorodeoxyadenosine (2-CdA) are considered to be cell cycle specific agents which require DNA synthesis for cytotoxicity. However, their efficacy in the treatment of CLL, an indolent lymphoid malignancy suggests additional mechanisms of action. Like cytosine arabinoside (AraC), F1 and 2-CdA gain access to the cell via a specific nucleoside transporter (NST) protein. To investigate the mode of action of these drugs in CLL, we used a fluorescent ligand for the NST (5'-(SAENTA- x8)-fluorescein) and 3-colour flow cytometry to determine NST expression on CD5+/CD19+ B-cells from the peripheral blood (PB) of patients with CLL. NST levels on these cells was found to be not significantly different from normal control lymphocytes (mean = 485 +/- 425) vs. (mean = 553 +/- 178). Exposure to varying concentrations (0, 3 microM and 30 microM) of F1 and 2-CdA, however, resulted in an upregulation of NST (mean = 1552 +/- 775 with 30 microM FL; mean = 3392 +/- 2197 with 30 microM 2-CdA) after 48. "Large" lymphoid cells (not present in normal PB) were found to express significantly more NST (mean = 2540 +/- 2861) and have a higher proliferative capacity than "small" cells (mean = 357 +/- 517 NST/cell). Incubation of CLL cells with F1 (n = 6) and 2-CdA (n = 8) in vitro over 48 h also resulted in an increase in the proportion of cells in S-phase (0 microM = 0.2 + 2 - 0.1; 30 microM FL = 2.4 +/- 2.0; 30 microM 2-CdA = 3.3 +/- 1.3) and a significant increase in morphologically identifiable apoptosis. Apoptosis was confirmed by flow cytometric DNA analysis (0 microM = 13 +/- 8%; 30 microM FL = 40 +/- 20%; 30 microM 2-CdA = 48 +/- 11%). In situ hybridization using a biotinylated cDNA bcl-2 probe demonstrated that bcl-2 mRNA expression was markedly decreased in treated cells after 24 h. These studies have demonstrated that: (1) NST expression on CLL lymphocytes is low; (2) in vitro exposure to the analogues increases both the level of NST expression and the % cells in S-phase; (3) exposure to the analogues downregulates bcl-2 expression and increases apoptosis.

Antigens, CD19↗

PubMed1994

Effects of valine, leucine, isoleucine, and a balanced amino acid solution on the seizure threshold to picrotoxin in rats.

During infusion of branched-chain amino acids (BCAAs) in humans, changes in ventilatory drive, sleeping pattern, and appetite have been reported. The mechanism by which BCAA exerts their effects on CNS remains unclear. An infusion of a BCAA solution (300 mg/kg) has previously been found to increase the seizure threshold in rats to the proconvulsant drug picrotoxin, an antagonist on the GABA-benzodiazepine receptor complex. In this study, each of the BCAAs given separately (valine, leucine, isoleucine; 300 mg/kg) (n = 10) increased the mean latency time to onset of seizures vs. placebo as an indication of an increased seizure threshold. A balanced amino acid solution (Vamin-Glucose) had no effect on the seizure threshold. Thus, these CNS effects are specific for BCAAs and occur with all three.

Amino Acids↗

PubMed1994

Multiple myeloma: expression of nucleoside transporters on malignant plasma cells and their relationship to cellular proliferation.

The expression of nucleoside transporters is a limiting factor in the pharmacology of the nucleoside analogue, cytosine arabinoside (AraC) and is associated with cellular proliferation. We investigated the expression of nucleoside transporters on plasma cells from the bone marrow of 51 patients with multiple myeloma by 2-colour immunofluorescence flow cytometry, utilising 5-(SAENTA-x8)-fluorescein, a fluorescent ligand for the nucleoside transporter and anti-CD38 conjugated to phycoerythrin, as CD38 expression has unique characteristics on plasma cells. Mean nucleoside transporter expression on bone marrow plasma cells from patients with myeloma (1777 +/- 2181 transporters/plasma cell) was not significantly different from expression on plasma cells from normal bone marrow (997 +/- 1096 transporters/plasma cell). However, analysis of disease subgroups revealed a significant trend towards increased transporter expression in patients with progressive disease compared to those with stable disease (chi 2 = 4.0, p < 0.05). Nucleoside transporter expression correlated significantly with the plasma cell labeling index (LI) (r = 0.45, p < 0.01) and serum thymidine kinase levels (r = 0.66, p < 0.01), both markers of cellular proliferation but not with c-myc oncoprotein expression. These findings suggest that flow cytometric measurement of nucleoside transporter expression on plasma cells provides a rapid and convenient measurement of disease activity or quiescence in myeloma.

ADP-ribosyl Cyclase↗

PubMed1992

Branched-chain amino acids increase the seizure threshold to picrotoxin in rats.

During infusion of branched-chain amino acids (BCAAs) in humans, changes in ventilatory drive, appetite, and sleep have been reported. The mechanism by which BCAAs exert their effects on CNS remains unclear. Picrotoxin is a proconvulsant drug, acting as an antagonist on the GABA-benzodiazepine receptor complex. Twenty rats were randomized to receive either an IP injection with 4% BCAAs (300 mg/kg; 8 ml/kg) (n = 10) or placebo (saline 8 ml/kg) (n = 10). The mean latency time from injection to onset of seizures was recorded as an indication of the seizure threshold. Latency time was significantly longer for BCAAs than for placebo, 11.2 (+/- 1.9) vs. 8.3 (+/- 1.8) min. Thus, a BCAA injection increased the seizure threshold to picrotoxin (p < 0.03). This suggests that BCAA infusion may exert effects on the GABA-benzodiazepine receptor complex.

Amino Acids, Branched-Chain↗

PubMed1990

[Fluid therapy changes in surgical treatment of abdominal aortic aneurysm].

The use of blood components and blood substitutes was studied in 25 patients undergoing surgical treatment for abdominal aortic aneurysm in 1983, and was compared with the use of such components in 44 patients operated in 1988. The use of blood components had decreased by 49% from 1983 to 1988. In 1988, erythrocytes were administered only when the hemoglobin concentration fell under 9 g/100 ml. The use of plasma postoperatively was reduced to a minimum. Normovolemia was maintained with polygeline, dextran, electrolytes and autotransfusion. The change in transfusion praxis did not lead to any reduction in postoperative hemoglobin values. The stay in hospital and the number of hours spent in a respirator were both reduced, and there was a general improvement in results.

Aorta, Abdominal↗

PubMed1968

Solid ion-exchange electrode selective for calcium ion.

A calcium-selective electrode with solid ion exchanger was prepared from a solution of the calcium salt of a dialkylphosphoric acid in collodion. The electrode responds rapidly and reproducibly to activity of calcium ion and demonstrates a selective response for calcium ion in the presence of alkaline earth and alkali metal cations.

Calcium↗