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Biomedical subjects

B A Jensen

Publications and source records attributed to B A Jensen.

At least 19 recordsLinked to original sources
PubMed2001

[The chronic Philadelphia chromosome-negative myeloproliferative syndrome I. Pathogenesis and pathophysiology].

In polycythaemia vera (PV) the erythroid progenitors proliferate autonomously independently of the circulating erythropoietin. The progenitors are hypersensitive to various growth factors, including insulin-like growth factor 1, which inhibits apoptosis in erythroid and myeloid progenitor cells. No change has been found in the erythropoietin (EPO) receptor. Thrombopoietin (Tpo) regulates the production of haematopoietic progenitor cells, particularly of platelets. By inhibiting apoptosis, this growth factor may be responsible for the autonomous proliferation of the megakaryocyte cell lineage in PV and idiopathic myelofibrosis (IMF), which are featured by highly elevated circulating Tpo levels. Thrombopoietin may also be involved in the pathogenesis of myelofibrosis and development of extramedullary haematopoiesis. Both fibrogenesis and angiogenesis in the bone marrow, spleen, and liver develop secondary to the release of various growth-promoting factors from the megakaryocyte cell lineage. The lesion of the pluripotent stem cell in PV and IMF seems to imply several defects, including lack of or decreased expression of the Tpo receptor, alterations in the sensitivity of progenitor cells to various growth factors, and alterations in important gene systems (Bcl-2), which govern cell survival. Essential thrombocytosis seems to be a heterogeneous disease entity, as about 50% of the patients have polyclonal haematopoiesis.

Hematopoiesis↗
PubMed2001

[The chronic Philadelphia chromosome-negative myeloproliferative syndrome II. Clinical findings, diagnostics and treatment].

Polycythaemia vera (PV) and essential thrombocytosis (ET) are clinically characterised by non-specific neurologic symptoms, peripheral circulatory disturbances (acrocyanosis, wounds, erythromelalgia) or abdominal symptoms. The treatment of PV includes phlebotomy, antiaggregation and cytoreduction. In ET, the primary treatment is also low-dose aspirin except for patients presenting with a haemorrhagic diathesis. Hydroxyurea may be associated with an increased risk of acute leukaemia or myelodysplasia. Therefore alpha-interferon and anagrelide should be considered in younger patients. Early cytoreductive therapy is advocated in patients with idiopathic myelofibrosis (IMF) to inhibit further progression of bone marrow fibrosis and further expansion of myeloid metaplasia in the spleen and liver. Treatment with androgens (danazol) and glucocorticoids may improve severe anaemia and thrombocytopenia. In younger patients, allogeneic bone marrow transplantation should be considered.

Bone Marrow↗
PubMed2001

[Acute thrombotic complication at the debute of the Philadelphia chromosome-negative myeloproliferative syndrome].

METHODS: We describe eight patients with a diagnosis of a chronic myeloproliferative disorder, characterised in most patients by severe thrombotic complications at the debut of the disease. RESULTS: The symptoms were life-threatening in seven patients: acute upper gastrointestinal haemorrhage from oesophageal varices in four, an acute abdominal catastrophy owing to mesenteric vein thrombosis with intestinal gangrene in two, and a large cerebral infarction, which was lethal, in one. The same patient also suffered a thrombosis of the axillary and subclavian veins. Neurological symptoms, with headache, visual disturbances, dizziness, and impaired memory, were initial cardinal symptoms. In two patients, explorative laparotomy was performed with intestinal resection owing to gangrene. One patient had a toe amputation. DISCUSSION: The above symptoms are explained by thrombosis in the microcirculation because of thrombocytosis and circulating platelet aggregates. In patients with polycythaemia vera, the elevated haematocrit contributes significantly to the impaired microcirculation. Early diagnosis and management of these disorders are of utmost importance to prevent the potentially life-threatening complications described above.

Acute Disease↗
PubMed2001

Therapy-related acute lymphoblastic leukaemia with MLL rearrangements following DNA topoisomerase II inhibitors, an increasing problem: report on two new cases and review of the literature since 1992.

A highly increased risk of myelodysplasia (MDS) and acute myeloid leukaemia (AML) is well established in patients previously treated for other malignancies with alkylating agents or topoisomerase II inhibitors. More recently, single cases of acute lymphoblastic leukaemia (ALL), often presenting balanced translocations involving chromosome band 11q23, have been observed. We present two such cases with t(4;11)(q21;q23), one of whom had previously received only single-agent chemotherapy with 4-epi-doxorubicin. A review of the literature since 1992 including these two patients reveals a total of 23 cases of ALL or lymphoblastic lymphoma after chemotherapy presenting balanced translocations to 11q23. All 23 patients had previously received at least one topoisomerase II inhibitor, and in two patients 4-epi-doxorubicin had been administered as single-agent chemotherapy for breast cancer. The latency period to development of t-ALL was 24 months or less in 20 out of 22 cases. The MLL gene was found to be rearranged in 14 out of 14 cases, and in three out of six cases the breakpoint was at the telomeric part of the gene, as observed in most cases of AML following therapy with topoisomerase II inhibitors. These results indicate that patients with ALL and balanced translocations to chromosome band 11q23 following chemotherapy with topoisomerase II inhibitors in the future should be included with cases of MDS or AML in calculations of risk of leukaemia.

Adult↗
PubMed2001

cDNA cloning and characterization of a high affinity aryl hydrocarbon receptor in a cetacean, the beluga, Delphinapterus leucas.

Some cetaceans bioaccumulate substantial concentrations of planar halogenated aromatic hydrocarbons (PHAHs) in their tissues, but little is known about the effects of such burdens on cetacean health. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related PHAHs cause toxicity via activation of the aryl hydrocarbon receptor (AHR), a member of the bHLH-PAS family of transcription factors. Differences in AHR structure and function are known to contribute to species-specific differences in susceptibility to PHAH toxicity. To ascertain the potential for PHAH effects in a cetacean, we characterized an AHR from the beluga whale, Delphinapterus leucas. The 3.2 kb cDNA encodes an 845-amino acid protein with a predicted size of 95.5 kDa. Overall, the beluga AHR shares 85% amino acid sequence identity with the human AHR and 75% identity with the mouse AHR Ah(b-1) allele. Beluga AHR protein synthesized in a rabbit reticulocyte lysate system demonstrated specific, high-affinity [(3)H]TCDD binding. Saturation binding analysis was used to compare the [(3)H]TCDD binding affinity of the in vitro-expressed beluga AHR with affinities of in vitro-expressed AHRs from a dioxin-sensitive mouse strain (Ah(b-1) allele) and humans. The beluga AHR bound [(3)H]TCDD with an affinity (K(d)= 0.43 +/- 0.16 nM) that was at least as high as that of the mouse AHR (K(d)= 0.68 +/- 0.23 nM), and significantly greater than that of the human AHR (K(d)= 1.63 +/- 0.64 nM). In electrophoretic mobility shift assays, the beluga AHR exhibited sequence-specific, Arnt-dependent binding to a dioxin responsive enhancer (DRE). Upon transient transfection into mammalian cells, the beluga AHR activated transcription of a luciferase reporter under control of a DRE-containing fragment of the mouse Cyp1a1 promoter. These results show that in an in vitro system, the beluga AHR possesses characteristics similar to those of AHRs from other mammals that are considered sensitive to toxic effects of PHAHs. Together, these results demonstrate that the use of in vitro-expressed proteins is a promising approach for addressing molecular and biochemical questions concerning PHAH toxicity in endangered or protected species.

Amino Acid Sequence↗
PubMed1997

Caring for caregivers.

In home health nursing, the whole family is the client. In a recent issue of Home Care Provider, Knox and Thobaben discussed the need to identify the significant family members who influence health care resources and decisions. Whatever their relationship to the patient, these individuals frequently provide his or her primary care.

Caregivers↗
PubMed1997

Explicating middle-range theory through methodological diversity.

Debates about methodological diversity and the most appropriate paradigm for scientific inquiry are still flourishing within the community of nurse scholars. Rather than continuing to debate these controversies, the authors of this article suggest that nurse researchers set aside methodological differences and move to discover the truths that will build the foundational base of nursing practice and, thus advance the discipline. This article discusses the multiple methodological perspectives used to explicate middle-range concepts from the theory and paradigm for nursing, Modeling and Role-Modeling. Each author will demonstrate how combining different approaches and methodologies can be helpful in exploring and validating middle-range concepts.

Adaptation, Psychological↗
PubMed1997

Transvaginal ultrasonographic assessment of Hyskon or lactated Ringer's solution instillation after laparoscopy: randomized, controlled study.

We sought to evaluate two common fluids placed in the pelvis after pelvic surgery for their ability to remain in the pelvis for a time thought adequate for prevention of adhesions. Thirteen patients undergoing operative laparoscopy were randomized to receive 250 ml 32% dextran 70 (Hyskon), 250 ml lactated Ringer's solution, or no fluid (control) at the end of surgery. Serial transvaginal ultrasonograms were obtained at 1 hr, 3 hr, 6 hr, 24 hr, 96 hr (4 days), and 168 hr (7 days) after surgery. Patients were asked about side effects of fluid instillation. The volume of lactated Ringer's solution declined rapidly after instillation, with no significant difference from control at 24 hr (12 ml versus 7 ml). The volume of Hyskon did not decline rapidly by 24 hr and remained higher than the volume in controls or those receiving lactated Ringer's solution (188 ml, P = 0.003). Although the volume of Hyskon remained higher than that of lactated Ringer's solution or fluid volume in control patients by days 4 and 7, this difference did not reach statistical significance (45 ml versus 7 ml and 14 ml respectively, P = 0.39, on day 4). Patients in all groups noted abdominal pain. One patient who received Hyskon developed severe vulvar edema and another developed dyspnea. We conclude that the volume of Hyskon in the peritoneal cavity after laparoscopy does not decline as rapidly as does that of lactated Ringer's solution; however, significant side effects may limit its usefulness. Transvaginal ultrasonography is useful in monitoring fluids placed in the pelvis for prevention of adhesions.

Dextrans↗
PubMed1992

[Emergency blood supplies and their use in elective surgery. Background and directives for rational blood reservation and transfusion strategy].

It cannot be anticipated that the increasing requirements for blood and blood components will be covered by proportionate expansion in gross supply. Blood component therapy, i.e. specific substitution of clinically important deficiencies, is recommended. In addition to being clinically rational, this principle of treatment provides enhanced utilization of resources, product quality and transfusion safety. By reviewing the literature, an unjustified excess of blood ordering and crossmatching was demonstrated in elective surgery. Practical application of Type and Screen (T&S) and thorough revision of preoperative blood ordering policies are safe and resource-saving measures, and guidelines such as these are proposed.

Blood Banks↗
PubMed1992

[Rational blood reservation for elective surgery. A prospective evaluation of blood reservation, use of transfusions and resources].

Danish and international studies have documented that preoperative blood ordering policy in elective surgery is extremely inefficient if not based on knowledge of actual transfusion frequencies and requirements. During a 12-month period, the impact of practical application of Type & Screen (T&S), and a thoroughly revised preoperative blood ordering policy in elective surgery, on crossmatch ordering, transfusion extent and safety were assessed prospectively. In addition, the effect on resource and laboratory economy was estimated, using the number of crossmatches, crossmatch to transfusion (C/T) ratio, out-dating, transfusion complications, and the proportional use of fractionated red cell products (erythrocyte concentrate and suspension) as efficiency parameters. In 86% out of 6,766 surgical procedures the recommendations were followed. A total of 1,736 patients had a preoperative cross-match of two or more units of blood and 25.1% were transfused during or within 48 hours following surgery. Only 2.4% of patients with T&S were transfused. Of the crossmatched blood 18.1% was actually transfused, and the overall crossmatch to transfusion ratio (C/T-ratio) was 5.33. In only 0.5% of operations, unexpected crossmatching and transfusions proved necessary during surgery. None of the reported transfusion complications were due to failure of the T&S procedure. During a period of increasing blood bank activities, as measured by the number of blood groupings and the blood turnover, a significant decrease in C/T-ratio and number of crossmatches was observed, corresponding to an estimated annual reduction of 11,000 crossmatches. Outdating declined from 9 to 3.2%, corresponding to savings of approximately 1,000 transfusion units annually, while the complication rate remained constant at 1.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Banks↗
PubMed1990

Prognostic factors in idiopathic myelofibrosis: a simple scoring system with prognostic significance.

In a prognostic univariate analysis of a series of 80 patients with idiopathic myelofibrosis the Hb-concentration, the platelet count and osteomyelosclerosis emerged as factors with prognostic significance. A Hb-concentration less than 10 g/dl was associated with a significantly shorter survival than a Hb-concentration greater than or equal to 10 g/dl. A platelet count less than 100 x 10(9)/l also implied a significantly shorter survival. Patients with osteomyelosclerosis on X-ray of the skeleton had a significantly better prognosis as compared to those without osteomyelosclerosis. In a multivariate regression analysis the Hb-concentration consistently emerged as an important prognostic parameter, whereas the platelet count was only of prognostic significance within the first 6 months from diagnosis and the presence of osteomyelosclerosis emerged as a favourable parameter at 3 and 5 years. Based upon the above parameters and spleen size, a prognostic scoring system was designed which categorized the patients into three prognostic groups with highly different survival times (low risk group = 69 months; intermediate risk group = 33 months; high risk group = 4 months).

Adult↗
PubMed1988

Plasma tetranectin is reduced in cancer and related to metastasia.

Tetranectin, a recently identified and characterized human plasma protein related to the fibrinolytic system, was significantly reduced in patients with various malignancies. Plasma tetranectin, measured by enzyme-linked immunosorbent assay (ELISA), was a significant discriminator regarding metastatic or nonmetastatic cancer. It had a high predictive specificity (0.93) and sensitivity (0.75) and only misclassified 14% of patients. Tetranectin may be related to the pathogenetically important processes leading to cancer spread and metastasis. In this respect, it may prove to be of discriminative importance clinically.

Adult↗
PubMed1988

Adrenocortical function in old age as reflected by plasma cortisol and ACTH test during the course of acute myocardial infarction.

Adrenocortical function, as reflected by sequential analysis of plasma cortisol and adrenocorticotropin (ACTH) test, was investigated in elderly patients (greater than or equal to 65 years) with acute myocardial infarction (AMI), and compared to young patients (less than or equal to 55 years) with AMI. Further, age-matched subjects admitted with ischaemic chest pain, in whom AMI was not verified, served as controls. Following infarction, plasma cortisol peaked within 24 hours in both age groups, whereupon the cortisol level gradually decreased till day 12. Plasma cortisol during AMI disclosed no age-related difference, but was significantly correlated to the localization of infarction and lactate dehydrogenase (LDH). The development of complications, i.e. hypotension, congestive heart failure, and arrhythmia, calling for therapeutic intervention, was solely correlated to infarct size, as estimated by peak LDH. Young and elderly patients responded equally and normally to ACTH stimulation, and in both groups a significant, positive correlation between the basal and the 30-min plasma cortisol was observed. Thus, we may conclude that in patients with AMI, the hypothalamic-pituitary-adrenocortical (HPA) response to stress and ACTH test shows no repression due to age.

Adrenal Cortex Function Tests↗
PubMed1988

Non-invasive evaluation of bone formation: measurements of serum alkaline phosphatase, whole body retention of diphosphonate and serum osteocalcin in metabolic bone disorders and thyroid disease.

Three noninvasive indices of bone formation, serum alkaline phosphatase (s-AP), 24-h whole body retention of diphosphonate (WBR), and serum osteocalcin (s-OC), the two lastnamed clearance-corrected, were compared in 121 patients with various bone disorders and in 50 patients with thyroid disease. In conditions with qualitatively normal matrix formation and mineralization, i.e. thyrotoxicosis, primary hyperparathyroidism, myxoedema and osteoporosis, the three indices deviated from average normal by about the same extent: 134%/128%/200%, 120%/113%/133%, 105%/100%/79% and 89%/86%/69%, respectively. A disproportionately marked deviation of s-AP was observed in states of abnormal matrix formation or mineralization, i.e. osteomalacia and Paget's disease: 430%/145%/282% and 348%/145%/202%, respectively. Furthermore, the formation indices correlate differently with s-calcium in hyper- and hypocalcaemic conditions. In primary hyperparathyroidism the respective r-values were 0.32/0.62/0.68, while an inverse pattern was observed in osteomalacia: -0.60/-0.51/-0.47. As very little is known about the secretion of AP and OC and their role in bone formation and mineralization, the cause(s) for the observed differences remain(s) uncertain.

Adult↗
PubMed1987

Immunohistochemical localization of a novel, human plasma protein, tetranectin, in human endocrine tissues.

A monospecific antibody to a plasminogen kringle 4-binding tetramer protein of human blood, tetranectin, was applied to various human endocrine tissues employing the peroxidase-antiperoxidase staining technique. Endocrine cells with a known protein or glycoprotein hormonal production such as chromophils (pituitary), follicular and parafollicular cells (thyroid), chief cells (parathyroid), hepatocytes (liver), islet cells (pancreas) and ganglion cells of the adrenal medulla displayed a convincing, positive staining reaction for tetranectin, which varied from cell to cell within the different tissues. The liver showed a distinct and universal reaction within almost all hepatocytes, thus raising suspicion of producing the bulk of tetranectin to the blood. Tetranectin has recently been characterized as a lectin-like protein with amino acid sequence homology to the core protein of a rat chondrosarcoma proteoglycan. Proteoglycans have been demonstrated in secretory granules of rat pituitary and pancreatic islet cells, where they probably serve as modulators in hormonal production. The granular, cytoplasmic immunohistochemical localization of tetranectin demonstrated in this study combined with the fact that tetranectin is known to attach to plasminogen and promote plasminogen activation catalysed by tissue plasminogen activator suggests that this protein might have a dual function, serving both as a regulator in the secretion of certain hormones and as a participant in the regulation of the limited proteolysis, which is considered important for the activation of prohormones.

Blood Proteins↗
PubMed1987

Antibody response to whole cells and teichoic acid of Staphylococcus aureus strain E 1369 in human sera.

A whole cell Staphylococcus aureus enzyme-linked immunosorbent assay (ELISA) using the protein A-deficient strain E 1369 as antigen was compared to an ELISA with cell-wall teichoic acid, extracted from the same strain, as antigen for the detection of IgG antibodies against S. aureus in human sera. A total of 178 serum samples from 119 patients with S. aureus endocarditis, complicated and uncomplicated septicaemia, non-S. aureus endocarditis and septicaemia were investigated together with sera from 155 healthy controls. The sensitivity in diagnosing S. aureus endocarditis was better for the whole cell-ELISA (83%) as compared to the teichoic acid-ELISA (61%), and the same was true for complicated septicaemia (41% vs 29%). The whole cell ELISA was also more specific for S. aureus infections with only 3.6% false positive test values compared to 7.1% for the teichoic acid-ELISA. The differences were however, not statistically significant. None of the assays were able to distinguish between complicated and uncomplicated S. aureus septicaemia.

Antigens, Bacterial↗
PubMed1987

Plasma fibronectin concentration in normal pregnancy and pre-eclampsia.

Plasma fibronectin concentration was determined by electroimmunoassay in 111 normal pregnant women and in 23 pregnant with evidence of pre-eclampsia. The plasma fibronectin concentration during the period of normal pregnancy showed a significant increase. In mild or severe pre-eclampsia patients, the plasma fibronectin concentration was significantly higher than that measured at normal 38-41 weeks of gestation. The present findings suggest that measurement of plasma fibronectin might be of diagnostic value in pre-eclampsia.

Adolescent↗