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Biomedical subjects

C Peterson

Publications and source records attributed to C Peterson.

At least 163 records · Page 9Linked to original sources
PubMed1994

Persistent right umbilical vein: sonographic detection and subsequent neonatal outcome.

OBJECTIVE: To review our experience with antenatal detection and subsequent neonatal outcome of fetuses with a persistent right umbilical vein. METHODS: In a prospective observational study, 33 cases of persistent right umbilical vein were detected during 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation. RESULTS: Persistent right umbilical vein was detected at a rate of one per 476 obstetric ultrasound examinations. Six of 33 (18.2%) fetuses with a persistent right umbilical vein had additional important congenital malformations. CONCLUSIONS: Careful second- and third-trimester ultrasound examinations can detect a persistent right umbilical vein. When this particular anomaly is detected, a thorough fetal anatomic survey, including echocardiography, should be performed to rule out more serious congenital malformations.

Abortion, Eugenic↗
PubMed1994

Day-to-day variability in azathioprine pharmacokinetics in renal transplant recipients.

The intraindividual and the interindividual variability in the pharmacokinetics of azathioprine (Aza) and its main metabolite 6-mercaptopurine (6-MP) were investigated in 10 renal transplant patients on 2 consecutive days, after repeated oral doses of Aza. On the 1st study, the dose-adjusted Aza AUC (0-6 h) ranged from 8.4 to 129.1 ngh*ml-1/mg*kg-1, mean 41.4 (+/- 37.6) ngh*ml-1/mg*kg-1. The corresponding values for the dose-adjusted 6-MP AUC (0-6 h) ranged from 37.9 to 172.0 ngh*ml-1/mg*kg-1, mean 91.7 (+/- 50.7) ngh*ml-1/mg*kg-1. The absolute percentage intraindividual difference in Aza AUC (0-6 h) between the two days ranged from 1.2% to 256.6% (mean 64.7%), and for 6-MP AUC (0-6 h) from 5.9% to 98.5% (mean 49.8%). However, no statistically significant difference was found when comparing the pharmacokinetics on the 2 study days. The mean half-life of Aza was 1.7 h and of 6-MP 1.2 h. Impaired renal function did not seem to affect the pharmacokinetics. No correlation was found between the given dose of Aza and AUC (0-6 h) for Aza or 6-MP. A strong correlation was found between the concentrations of Aza and 6-MP obtained at 2 h after the oral dose and the corresponding AUCs (0-6 h) (Aza: r = 0.85, p < 0.001, n = 20; 6-MP: r = 0.9, p < 0.001, n = 20). We conclude that the intraindividual variability in Aza pharmacokinetics is marked, but it is less pronounced than the even larger interpatient variability found in this study and previously described.

Administration, Oral↗
PubMed1994

Coping with the late effects: differences between depressed and nondepressed polio survivors.

This study examined differences between depressed and nondepressed individuals with a history of paralytic poliomyelitis in terms of demographics, health status and coping strategies. The prevalence of distress and depression in this group of 116 polio survivors was determined. Subjects completed the Brief Symptom Inventory, the Coping with Disability Inventory and a questionnaire concerning their polio histories and self-perceptions of health. Medical assessments were performed by physicians. Only 15.8% of the sample had scores indicating depression and elevated distress. Depressed/distressed polio survivors were more likely to: be living alone, be experiencing further health status deterioration, seek professional help, view their health as poor, report greater pain, be less satisfied with their occupational status and their lives in general and exhibit poorer coping outcome behaviors in relation to their disability. Three factors in coping with the late effects of polio were identified through a factor analysis of the Coping with Disability Inventory: positive self-acceptance, information seeking/sharing about the disability and social activism. Differences between depressed/distressed and other polio survivors were found across these three factors, with depressed/distressed subjects having significantly lower coping scores. These and other results are discussed.

Adaptation, Psychological↗
PubMed1993

Molecular cloning, functional expression and localization of an inward rectifier potassium channel in the mouse brain.

We have cloned an inward-rectifier potassium channel from a mouse brain cDNA library, studied its distribution in the brain by in situ hybridization and determined the chromosomal localization of the gene. A mouse brain cDNA library was screened using a fragment of the mouse macrophage IRK1 cDNA as a probe. Two duplicate clones of approximately 5.5 kb were obtained. Xenopus ococytes injected with cRNA derived from the clone expressed a potassium channel with inwardly rectifying channel characteristics. The amino acid sequence of the clone was identical to that of IRK1 recently cloned from a mouse macrophage cell line. In situ hybridization study showed the mouse brain IRK1 to be generally distributed throughout the brain, but in particular subsets of neurons at high levels. The gene was placed in the distal region of mouse chromosome 11, which contains several uncloned neurological mutations. These results provide the first demonstration of the cloning and distribution of an inward rectifier potassium channel from the nervous system.

Animals↗
PubMed1993

Induction of stathmin mRNA during liver regeneration.

Stathmin is a 19 kDa phosphoprotein, and is proposed to play a role in signal transduction in response to various extracellular stimuli that promote cellular growth and/or differentiation. We examined stathmin mRNA expression during development and liver regeneration in mice. Stathmin mRNA expression declined during the post-natal period and was undetected in adult liver. 36 h after partial hepatectomy, stathmin mRNA was rapidly induced and remained at elevated levels for at least 10 days. In situ hybridization experiments confirmed that stathmin mRNA expression occurred in hepatocytes. These results indicate that the stathmin gene expression appears to be repressed during the post-natal liver development, and is de-repressed by liver regeneration, which suggests that stathmin may be a good molecular marker of liver plasticity.

Aging↗
PubMed1993

Genes necessary for expression of a virulence determinant and for transmission of Plasmodium falciparum are located on a 0.3-megabase region of chromosome 9.

Virulence of the human malaria parasite Plasmodium falciparum is believed to relate to adhesion of parasitized erythrocytes to postcapillary venular endothelium (asexual cytoadherence). Transmission of malaria to the mosquito vector involves a switch from asexual to sexual development (gametocytogenesis). Continuous in vitro culture of P. falciparum frequently results in irreversible loss of asexual cytoadherence and gametocytogenesis. Field isolates and cloned lines differing in expression of these phenotypes were karyotyped by pulse-field gel electrophoresis. This analysis showed that expression of both phenotypes mapped to a 0.3-Mb subtelomeric deletion of chromosome 9. This deletion frequently occurs during adaptation of parasite isolates to in vitro culture. Parasites with this deletion did not express the variant surface agglutination phenotype and the putative asexual cytoadherence ligand designated P. falciparum erythrocyte membrane protein 1, which has recently been shown to undergo antigenic variation. The syntenic relationship between asexual cytoadherence and gametocytogenesis suggests that expression of these phenotypes is genetically linked. One explanation for this linkage is that both developmental pathways share a common cytoadherence mechanism. This proposed biological and genetic linkage between a virulence factor (asexual cytoadherence) and transmissibility (gametocytogenesis) would help explain why a high degree of virulence has evolved and been maintained in falciparum malaria.

Agglutination↗
PubMed1993

Laser facilitated angioplasty and thrombolysis in acute myocardial infarction complicated by prolonged or recurrent chest pain.

To date, application of laser angioplasty in acute myocardial infarction (MI) has not been reported. In nine patients with acute myocardial infarction complicated by continuous or recurrent severe ischemia and chest pain, a mid-infrared, solid-state, pulse-wave holmium/thulium:YAG coronary laser was applied. In six of these patients the laser was specifically utilized for the purpose of coronary thrombolysis. In each case a guidewire was placed across the stenosis and a multifiber laser catheter was utilized, emitting 250-600 mJ/pulse at 5 Hz, followed by adjunctive balloon angioplasty. Laser success (defined as ability to cross the lesion, reduction of > or = 20% in stenosis and thrombolysis when a thrombus is present) was achieved in all patients. Final angiograms revealed residual stenosis < or = 30%, adequate thrombolysis and no major complication (MI, perforation, emergency CABGS, CVA, death) in each patient. Clinically, all nine patients improved, survived the acute infarction and were discharged. This initial clinical experience demonstrates the feasibility and safety of holmium/thulium:YAG laser application in thrombolysis and plaque ablation in selected patients who experience acute myocardial infarction complicated by prolonged or recurrent ischemia and chest pain.

Adult↗
PubMed1993

Fetal heart circumference as a predictor of menstrual age in fetuses affected by disturbances in growth.

OBJECTIVE: The purpose of this study was twofold: (1) to evaluate the relationship between fetal heart circumference and gestational age and (2) to determine the effect, if any, of disturbances in fetal growth on heart circumference. STUDY DESIGN: Heart circumference was measured in 262 women with normal gestations (control group) and in two study groups consisting of 52 large-for-gestational age 32 small-for-gestational age fetuses. Standardized, gestational age-adjusted values in the two study groups were compared with normative data provided by the control group. RESULTS: There was a close correlation (R2 = 0.94) between heart circumference and gestational age in normally growing fetuses. Disturbances of fetal growth (i.e., macrosomia and growth retardation) were found to have an inconsistent effect on heart circumference. CONCLUSION: Heart circumference cannot be used as an independent parameter for gestational age evaluation in fetuses with disturbances of growth.

Animals↗
PubMed1993

Helpless behavior.

In the present research, we investigated helpless behavior and the responses it elicits from others. Study One used the act-frequency approach to develop a self-report measure of prototypically helpless behaviors. In a sample of college students (n = 75), this measure was validated against ratings by others. Many of the prototypically helpless behaviors we identified were interpersonal in nature, implying that they entail dependency and perhaps manipulativeness. In Study Two, we asked young adult (n = 249) Ss how they responded to people who showed varying amounts of helplessness. The most frequent response was trying to help the helpless individual feel better. As the frequency of helpless behavior increased, people were less likely to try to make him or her feel better, less likely to go along with the helpless individual, more likely to become angry and more likely to ignore or avoid this individual. Implications of these results for applications of the learned helplessness model were discussed, in particular the need to be cautious in assuming that all instances of observed passivity are good examples of learned helplessness.

Adult↗
PubMed1993

Effect of verapamil on daunorubicin accumulation in human leukemic cells with different levels of MDR1 gene expression.

The purpose of the present study was to evaluate the distribution of the multiple drug resistance phenotype in leukemic cells with different levels of mdr1 gene expression. Peripheral leukemic cells from 8 patients (5 with detectable and 3 with undetectable mdr1 RNA levels) were incubated with daunorubicin (1 microM) in the absence and presence of verapamil (6.6 microM). Daunorubicin accumulation in individual cells was analysed by flow cytometry. Verapamil increased (16-45%) the mean daunorubicin accumulation in 7 of the 8 cell samples. In cells from 4 of these 7 patients, the fluorescence histograms showed a general increase of daunorubicin accumulation. The increase was limited to a small subpopulation of cells in one patient. In the remaining two patients an increase of daunorubicin accumulation was seen in the majority of cells, while cells with the highest accumulation were unaffected. In conclusion, verapamil can increase daunorubicin accumulation in leukemic cells with and without detectable mdr1 gene expression and the increase seems to affect the majority of the cell population.

Adult↗
PubMed1993

Depressive symptoms among Vietnamese-American college students.

Fifty Vietnamese-American college students completed questionnaires measuring depressive symptoms, stressful life events, and acculturation to Vietnamese society versus U.S. society. In contrast to the findings of earlier studies, in which attention was limited to depressive symptoms specific to traditional Vietnamese culture, no gains in reliability or validity were apparent when analyses were limited to these symptoms. Acculturation to U.S. society was positively associated with increased reports of depressive symptoms, as was the occurrence of stressful life events. Implications of these findings are discussed in terms of the changing nature of the Vietnamese-American population.

Acculturation↗
PubMed1993

Conditioned nausea after cancer chemotherapy and autonomic nervous system conditionability.

There are marked individual differences in conditioned nausea after cancer chemotherapy. To examine if part of this variation is associated with individual differences in autonomic nervous system conditionability, the present study addressed whether patients with conditioned nausea acquired conditioned heart rate and electrodermal responses at a different rate than patients without conditioned nausea. Of 28 relapse-free patients who had completed cisplatinum treatment for testicular cancer between 1981 and 1986, 10 reported persistent conditioned nausea, 8 extinguished conditioned nausea and 10 no conditioned nausea. These three groups were subjected to a differential conditioning paradigm with 8 sec pictorial stimuli (circles and triangles) serving as conditioned stimuli for an unconditioned electric shock while heart rate and electrodermal activity was monitored. There were 4 habituation, 8 acquisition and 8 extinction trials with each of the two cues. Analyses of variance using nausea status as the independent variable and physiological responses as the dependent lended some support to the notion that conditioned heart rate deceleration developed in response to the reinforced compared to the nonreinforced cue during acquisition in the two groups with persistent or extinguished conditioned nausea but not in the group with no conditioned nausea. In addition, patients that displayed good, as compared to poor heart rate conditionability during acquisition, were more likely to have persistent conditioned nausea, whereas those who showed poor heart rate conditioning mostly were those without conditioned nausea. Electrodermal variables revealed no systematic differences between groups. This tentatively supports that individual differences in parasympathetic but not sympathetic nervous system conditionability may be associated with individual differences in conditioned nausea resulting from cancer chemotherapy.

Adult↗
PubMed1993

On the interaction between cytosine arabinoside and etoposide in vivo and in vitro.

Cytosine arabinoside (ara-C) and etoposide are often used in combination in the treatment of acute myelocytic leukemia (AML). The intracellular phosphorylation of ara-C to its 5'-triphosphate (ara-CTP) is a prerequisite for its cytotoxic effects. It has been shown in vitro that etoposide can impair the formation of ara-CTP in leukemia cells. The present study was undertaken in order to elucidate whether this interaction may be of clinical importance. Leukemia cells were isolated from 3 patients with acute myelocytic leukemia and incubated in medium (RPMI-1640) with or without 10% fetal calf serum or in human plasma. When the cells were incubated in RPMI-1640 with ara-C (10 mumol/l) and etoposide during 2 h, the formation of ara-CTP was decreased to 71 +/- 18 (mean +/- S.D.) and 30 +/- 15% of control at 1 and 10 micrograms/ml etoposide, respectively. When the cells were incubated in human plasma, the formation of ara-CTP was not influenced by the presence of etoposide (101 +/- 6 and 103 +/- 20% at 1 and 10 micrograms/ml etoposide). When incubated in RPMI supplemented with 10% fetal calf serum, the corresponding figures were 81 +/- 8 and 70 +/- 20%. Six patients with AML were therefore treated with ara-C 0.5 or 1.0 g/m2 as a 2-h infusion every 12 h and, during 1 h before the second ara-C infusion, 100 or 200 mg/m2 etoposide was administered. The median change in the AUC of cellular ara-CTP between the first and second ara-C dose was 0% (-37 to +21%). The corresponding median change in rate of accumulation of ara-CTP in leukemia cells was 12% (-26 to +110%). The concentration of etoposide in plasma during the ara-C infusion was 18.7 +/- 5.1 micrograms/ml while the non-protein bound etoposide was 0.73 +/- 0.34 micrograms/ml. Thus, despite exposure to higher etoposide concentrations in vivo than in vitro, no impairment of ara-CTP formation was seen in the patients. This corresponds to the results obtained when leukemic cells were incubated in plasma. It is concluded that the inhibition of ara-CTP formation by etoposide seen in vitro is offset by the high protein binding of etoposide in plasma (96%) and that etoposide does not impair the formation of ara-CTP in leukemia cells in vivo during treatment with standard-dose etoposide.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

High concentrations of eosinophil cationic protein and eosinophil protein X in eosinophilic pleural effusions.

To analyze the association of the eosinophil granulocyte with pleural effusions, we measured the concentrations of two eosinophil proteins, eosinophil cationic protein (ECP) and eosinophil protein X (EPX), in pleural fluid and serum of 92 patients with pleural effusions of various causes. We observed significantly higher ECP and EPX concentrations in eosinophilic than in noneosinophilic pleural effusions (p < 0.001 and p < 0.05, respectively) and a positive correlation between the concentrations of both eosinophil proteins in pleural fluid and the total number of eosinophils in pleural fluid (ECP: r = 0.66, p < 0.0001; and EPX: r = 0.62, p < 0.0001). There was a positive correlation between the concentrations of ECP in pleural fluid and serum (r = 0.74, p < 0.0001) and between the concentrations of EPX in pleural fluid and serum (r = 0.41, p < 0.001). High ECP and EPX concentrations in pleural fluid indicated nonspecific etiology and not tuberculosis as the cause of the effusion. Our results suggest that eosinophils in pleural effusions release eosinophil proteins and probably actively participate in the local inflammatory reaction.

Blood Proteins↗
PubMed1993

In vivo accumulation of etoposide in peripheral leukemic cells in patients treated for acute myeloblastic leukemia; relation to plasma concentrations and protein binding.

Since etoposide interacts with the nuclear enzyme topoisomerase II, the drug concentrations in the malignant cells during chemotherapy may have clinical correlates. Plasma protein binding of etoposide is extensive (94%) and alterations of the non-proteinbound fraction affect pharmacokinetic behavior of the drug. The pharmacokinetics of etoposide was therefore studied in plasma, total and non-proteinbound concentrations, and in leukemic cells isolated from peripheral blood samples from 22 patients after the first dose of the induction treatment for acute myelocytic leukemia. Fourteen patients received 100 mg/m2 and eight patients 200 mg/m2 as a 1 h infusion. The mean area under the concentration versus time curve AUC(0-infinity) in plasma was at the lower dose level 78.4 +/- 29.1 (mean +/- S.D.) micrograms/ml x h and 201.0 +/- 56.5 micrograms/ml x h at the higher dose level. The fraction of non-proteinbound etoposide in plasma was 5.2 +/- 3.4 and 5.4 +/- 2.1% in the two treatment groups. AUC(0-16h) in leukemic cells was 8.4 +/- 8.7 and 22.4 +/- 12.1 micrograms/ml x h at the two dose levels, respectively. The cellular etoposide concentration was 12.1 +/- 7.9 and 14.7 +/- 5.1% of the plasma concentration at the end of the infusion. The interpatient variability in cellular drug levels was considerable and exceeded the variability in plasma concentrations. Cellular accumulation of etoposide could be important for treatment outcome.

Adult↗
PubMed1993

The influence of IL-3, IL-5, and GM-CSF on normal human eosinophil and neutrophil C3b-induced degranulation.

The priming effect of interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte/macrophage-colony stimulating factor (GM-CSF) on eosinophil and neutrophil degranulation was studied. Granulocytes were obtained from normal donors, and degranulation was induced by incubation with serum-opsonized Sephadex particles. The released amounts of eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO), and lactoferrin (LF) were measured by radioimmunoassay (RIA). The effect of IL-5 was dose- and time-dependent, with a maximal enhancement of ECP and EPX release of 71% (P < 0.03) and 66% (P < 0.03), respectively. Neutrophil degranulation, however, was unaffected. IL-3 was marginally effective, whereas GM-CSF seemed to act as a secretagogue for both eosinophil and neutrophil degranulation. We conclude that IL-5 selectively primes eosinophil degranulation, whereas IL-3 and GM-CSF seem to act as secretagogues for eosinophils and neutrophils. The results indicate that IL-5 may be involved in the priming of eosinophils as observed in patients with asthma and hypereosinophilic syndrome (HES).

Blood Proteins↗