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Biomedical subjects

J Petersen

Publications and source records attributed to J Petersen.

At least 127 records · Page 7Linked to original sources
PubMed1994

Single-photon emission tomography studies of rubidium-81 in the detection of ischaemic heart disease, using a stress-reinjection protocol.

The present study was designed to determine the feasibility of using single-photon emission tomography (SPET) imaging with rubidium-81 (T1/2 = 4.54 h) to detect ischaemic heart disease, using a stress-reinjection protocol and a specially constructed 511-keV hexagonal hole collimator for a standard gamma camera. The diagnostic performance of 81Rb SPET in detecting coronary artery disease (CAD) was investigated in 52 patients with a high prevalence of CAD. Coronary arteriography was performed in 34 patients, 25 of whom were classified as having significant stenosis (> or = 50%). At peak exercise (Cornell protocol), 111-222 MBq 81Rb was injected i.v. for stress imaging, and after 3 h of rest, 74-111 MBq was reinjected for rest imaging. The displayed short- and long-axis slices and the polar map images were interpreted qualitatively. In comparison to coronary arteriography, which served as the gold standard, the performance of 81Rb SPET revealed a sensitivity of 95% for the detection of CAD. Images of diagnostic quality were obtained in all patients, these being comparable to thallium-201 SPET images. In conclusion, these results indicate that the described method can be routinely used for the positron emitter 81Rb with a conventional gamma camera and special shielding. 81Rb has the well-known advantages of a potassium analogue and 81Rb SPET permits better visualization, particularly of the posterior wall of the myocardium, due to the higher photon energy. Considering the typical dose of 201Tl used for SPET (74-148 MBq), a 81Rb SPET scan imposes a significantly lower radiation burden on the patient.

Adult↗
PubMed1994

In vivo effect of beta 2-microglobulin on bone resorption.

beta 2-Microglobulin (beta 2-M) deposits have been found in the destructive bone lesions associated with dialysis-related amyloidosis. To examine whether beta 2-M can cause bone resorption in vivo, doses of beta 2-M alone were compared with parathyroid hormone (PTH), aluminum, and vehicle alone. Eleven injections of 10 micrograms each were made over a period of 56 hours into the subcutaneous tissue overlying the occipital region of mice. Using a computerized image analysis system we measured (1) periosteal and inner bone length, (2) bone marrow interface length, and (3) the extent of resorption along these surfaces expressed as percentage of total length. Injections of either beta 2-M or PTH were associated with 22% +/- 4% and 25% +/- 4% resorption of periosteal surface, respectively, and 15.9% +/- 2% and 19.9% +/- 5% resorption of marrow bone surfaces, respectively, compared with control. In contrast, aluminum did not increase bone resorption over controls. The simultaneous injection of calcitonin, an osteoclast inhibitor, with beta 2-M or PTH did not increase periosteal resorption over controls. The resorption of inner bone surface was similar in all groups. These studies show that beta 2-M and PTH cause bone resorption in the bone surfaces proximate to the site of injection. This suggests that beta 2-M may contribute to the development of the bone cysts in dialysis-related amyloidosis.

Aluminum↗
PubMed1994

Renin-angiotensin system in neonatal rats: induction of a renal abnormality in response to ACE inhibition or angiotensin II antagonism.

In experiments designed to analyze cardiovascular structure in response to antihypertensive therapy with an ACE inhibitor, we decided to start very early in life with the aim to prevent blood pressure increases and the development of vascular structural changes. In these treated groups of rats we unexpectedly observed that after they were weaned, their water consumption and urine volume, respectively, increased substantially. The present study was designed to determine if inhibition of the renin-angiotensin system produced similar effects in different strains of rats, and focused on characterizing the abnormal fluid balance occurring as a consequence to neonatal treatment with ACE inhibitors or angiotensin II blockers. Three-day-old Wistar Kyoto (WKY), Wistar (WR) and spontaneously hypertensive rats (SHR) were given either saline, enalapril, captopril, losartan and the AT2 blocker, PD123319, in the same amount of volume for 20 days. Treatment was stopped and rats were examined with regard to renal morphology at 4, 14 and 30 weeks of age. In addition, water consumption, urine volume, urine electrolytes and osmolality were analyzed at 14 weeks of age, that is, 10 weeks off treatment. Early treatment with the ACE inhibitors, enalapril and captopril, and the AT1 blocker, losartan, but not the AT2 blocker, PD 123319, in the SHR and in the normotensive strains WKY and WR produced persistent, irreversible histopathological renal abnormalities in adult life, long after the rats had been taken off treatment. These abnormalities consisted of mainly cortical tubulointerstitial inflammation, various degrees of papillary atrophy and pelvic dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin I↗
PubMed1994

[Expert systems in medicine: possible uses in anesthesia].

The euphoric assumption that powerful computers fed with sophisticated software programmes may serve as a substitute for human knowledge and decision making has been replaced by a more realistic concept of how computers may help in collecting data and their interpretation on the basis of human knowledge and experience. The computer is now used as a dedicated tool to support man in overtaking cumbersome and monotonous processes and tedious calculations. Running 24 hours a day, a specific feature of the computer is that depending on unequivocal software programmes it does neither forget or alter commands and information. Computer programmes imitating human thinking and information processing are called expert or knowledge based systems. These are especially useful when multiple possible combinations of data make a given task very complex. This review presents several systems used in different medical disciplines to describe fundamental ideas, different problem-solving methods, techniques and possible working fields including anaesthesia. It is made clear why computers have found widespread use in all administrative areas. In contrast, no system comparable in potency has been developed for use in clinical medicine in spite of 25 years of research in expert systems. This review starts with a definition of expert knowledge and the appropriate transformation of this knowledge to the computer. In addition, a general survey about the structure of expert systems and a state of the art in some current problem solving methods is given. Additional aspects and restrictions including technical, psychological and legal problems which seem to be unimportant from the outside but are essential for the development of expert systems are presented.

Anesthesia↗
PubMed1994

Management of thyroid papillary carcinoma with radioiodine in a patient with end stage renal disease on hemodialysis.

Metastatic papillary carcinoma was diagnosed in a 42-year-old woman. The cancer had invaded out of the gland and was present in many lymph nodes. After her surgical procedure, she was advised to have radioiodine. However, the patient had total renal failure and was on dialysis. Studies were carried out using a tracer dose of 2 mCi of radioiodine, demonstrating that approximately 60% of the radioactivity in the body was removed with each dialysis. Calculations indicated that a meaningful dose of radiation could be delivered to residual thyroid and metastases with 100 mCi of radioiodine and the total body radiation would be < 100 rad delivered over several days. Based on these analyses, she received 100 mCi of I-131 on two separate occasions and on follow-up scan, clinical evaluation and thyroglobulin measurement is free of disease.

Adult↗
PubMed1994

Myoglobinuric acute renal failure in a cardiac transplant patient taking lovastatin and cyclosporine.

Acute renal failure can occur in cardiac transplant patients for a variety of reasons. A case of a patient who developed acute renal failure secondarily to drug-induced rhabdomyolysis is reported. The literature regarding acute renal failure and lovastatin and other 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors is reviewed. The potential mechanisms of myoglobinuria and nephrotoxicity and the therapeutic implications are discussed.

Acute Kidney Injury↗
PubMed1994

[The effect of different flavophospholipol levels in rabbit feed on the fattening rate of hybrid rabbits].

The present study was designed to evaluate the effects of dietary flavophospholipol ("Bambermycin") levels on the growth performance in 400 hybrid rabbits from weaning at 28 days until slaughter at 74 days of age. The fryers were randomly assigned to one of the four dietary treatments that consisted of either 0, 4, 8 or 16 ppm supplemental flavophospholipol. Each treatment was applied to 100 animals each. Dietary treatments exerted no significant effects on live weight, daily weight gain and feed consumption across the entire fattening period. However, daily weight gains in treated fryers were increased by 2.4% on the average. The only significant treatment effect was found in feed conversion (food/gain) in fryers fed 16 ppm supplementation; kilogram food intake per kilogram weight gain was reduced by 0.16 kg as compared to the control group. Mean feed conversion in treated groups was improved by 3.5% on the average. In addition of flavophospholipol a significantly decreased mortality was observed. It was remarkable, that losses caused by infection in control were exclusively due to infections by Bordetella species, while the treated groups were only caused by Pasteurella species.

Animal Feed↗
PubMed1993

Characterization of human tissue factor pathway inhibitor variants expressed in Saccharomyces cerevisiae.

Human tissue factor pathway inhibitor (TFPI) and three derivatives with deletions of: 1) the complete COOH-terminal third of the polypeptide including the third Kunitz domain, 2) the third Kunitz domain alone, or 3) the penultimate basic COOH-terminal region alone were expressed in yeast as secreted products. High expression yield was obtained only with the derivative that lacked both the third Kunitz domain and the penultimate COOH tail (TFPI1-161). The purified short form was heterogeneously glycosylated with a high mannose glycan. The specific activities of the different mutant polypeptides toward FXa.tissue factor.FVIIa in a chromogenic assay were similar to that of TFPI expressed in baby hamster kidney cells, suggesting that correct folding takes place in yeast and that neither the third Kunitz domain nor the COOH-terminal region is required for this activity. However, in a clotting assay the anticoagulant activities of yeast-produced TFPI and the shortened derivative TFPI1-161 were about 5- and 50-fold lower, respectively, than for full-length TFPI from mammalian cells. Clotting assays with purified short form TFPI showed that it acted mainly via inhibition of FVIIa.tissue factor rather than FXa. The anticoagulant activity of short form TFPI was comparable with that of high affinity antibodies toward tissue factor.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of the trefoil peptide human spasmolytic polypeptide (hSP) produced in yeast.

Recombinant human spasmolytic polypeptide (r-hSP) has been produced in relatively large amounts in Saccharomyces cerevisiae. The two intronless trefoil domains of the hSP-DNA were cloned separately by PCR from human genomic DNA, and the remaining parts of the gene synthesized. Recombinant plasmids were constructed to encode a fusion protein consisting of a hybrid leader sequence and the hSP sequence. The leader sequence serves to direct the fusion protein into the secretory pathway of the cell and to expose it to the Kex 2 processing enzyme system. The secreted r-hSP was found in a glycosylated and an non-glycosylated form. The two forms of r-hSP were purified from the yeast fermentation broth by a combination of ion-exchange chromatography and preparative HPLC. The overall yield from 8 litres of fermentation broth was 160 mg r-hSP and 219 mg glycosylated r-hSP corresponding to 50% and 34%, respectively. The structure of the r-hSP and the glycosylated r-hSP was determined by amino acid analysis and carbohydrate composition analysis as well as by peptide mapping, amino acid sequencing and mass spectrometric analysis.

Amino Acid Sequence↗
PubMed1993

Cellular immune responses and pathogenesis in c-ANCA positive vasculitides.

Very little is known about the cellular immune response in c-ANCA (classical anti-neutrophil cytoplasm antibodies) positive vasculitides or Wegener's granulomatosis (WG). The present review is mainly based on published and unpublished observations of the Cattegat Study Group of Wegener's Granulomatosis. Immunohistochemical examinations of nasal biopsies from untreated patients with active WG revealed the presence of substantial amounts of cells belonging to the immune system (CD3+, CD4+, CD8+, CD20+, CD38+ and CD68+). The IgG response of peripheral mononuclear cells from untreated WG patients to PWM and EBV stimulation was significantly depressed when examined by the reverse haemolytic plaque forming cell assay. T lymphocyte proliferation was observed by in-vitro stimulation with extract of human neutrophil alpha granules, containing the autoantigen for c-ANCA, proteinase-3, only in patients with c-ANCA and active disease. Electron microscopy of biopsies from nasal lesions in untreated patients with active WG did not show structural abnormalities of the organelles of macrophages, giant cells or epithelioid cells. It is concluded that the immune response leading to c-ANCA production involves the full spectrum of immunocompetent cells normally engaged in IgG production to a foreign antigen. This would be in agreement with a theory of cross reactivity of proteinase-3 with a microbial antigen as a pathogenetic mechanism.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Increased secretion of tumor necrosis factor-alpha, interleukin-1-beta, and interleukin-6 by alveolar macrophages from patients with sarcoidosis.

BACKGROUND: Alveolar macrophages from patients with sarcoidosis were analyzed for their ability to secrete tumor necrosis factor-alpha (TNF-alpha), interleukin-1-beta (IL-1-beta), and interleukin-6 (IL-6). RESULTS: Constitutive release of all three monokines in these patients was concomitantly increased in the active state of disease in comparison with inactive sarcoidosis or healthy control subjects. Alveolar macrophages from patients with inactive sarcoidosis compared with cells from healthy subjects showed increased spontaneous secretion of TNF-alpha and IL-6 only, whereas the constitutive release of IL-1-beta was similar as in healthy volunteers. In vitro stimulation of alveolar macrophages from healthy control subjects with lipopolysaccharide or pokeweed mitogen led to a time- and dose-dependent enhanced secretion of TNF-alpha, IL-1-beta, and IL-6. In a similar manner, with corresponding cells from patients with sarcoidosis the secretion of all three cytokines could be further increased by stimulation with lipopolysaccharide or pokeweed mitogen. CONCLUSIONS: The data presented indicate that an increased release of TNF-alpha, IL-1-beta, and IL-6 correlates to disease activity and may play a critical part in the pathogenesis of sarcoidosis.

Adult↗
PubMed1993

[Comparison of complications after intra- and extracapsular cataract extraction with lens implantation. Results of a prospective, randomized, clinical study].

BACKGROUND: The postoperative complications of ICCE with ACL implantation are compared with those of ECCE and PCL. Our clinical experience with ICCE and ACL implantation can not confirm the widespread rejection of this method. PATIENTS AND METHOD: A prospective, randomized, clinical study with participation of medical statisticians was performed. A total of 190 patients with ICCE and ACL and 170 patients with ECCE and PCL were followed up for 2 years. The follow-up examinations were performed upon dismission from the hospital, after 6, 12 and 24 months. The data were compiled in a computer program designed for this study and evaluated by the statisticians. The surgical procedures and the surgeons were defined prior to the beginning of patient recruitment. RESULTS: ICCE with ACL shows much less postoperative complications as usually emphasized. There were only 2 (1.2%) of retinal detachment and no case of corneal decompensation. Cystoid macular edema 8 (4.7%), postoperative vitreous prolaps into the anterior chamber 4 (2.3%) and spontaneous complaints of pain 16 (9.4%) occurred in a low percentage after ICCE with ACL. These complications did not occur after ECCE with PCL. The patients with ECCE and PCL showed capsular fibrosis in 48 (28%) making it the most frequent complication of the whole study. 33% of these patients required YAG-laser capsulotomy. Since retinal detachment occurs in 2.5% after YAG-laser capsulotomy we can not regard capsular fibrosis as a totally harmless complication. It is noteworthy that visual acuity is almost identical 1 year after surgery in both methods. CONCLUSIONS: The results of this study show that the evaluation of ICCE with ACL is too negative. The elimination of postoperative complications in this method is more difficult. ECCE with PCL is burdened by frequent capsular fibrosis. Visual acuity is almost the same in both methods 1 years after the operation. ACL-implantation remains our method of choice for secondary implantation in patients with an intact iris diaphragm.

Aged↗
PubMed1993

Differences in cytokine secretion by intestinal mononuclear cells, peripheral blood monocytes and alveolar macrophages from HIV-infected patients.

Mononuclear cells of the lamina propria (LpMNC), isolated from endoscopically taken biopsies of the large bowel from AIDS patients, were analysed for their ability to secrete tumour necrosis factor-alpha (TNF-alpha), IL-1 beta and IL-6. Stimulation of LpMNC from normal controls with pokeweed mitogen (PWM) led to a time- and dose-dependent enhancement of TNF-alpha, IL-1 beta and IL-6 secretion. In contrast, PWM stimulation of LpMNC from AIDS patients resulted in only a small increase in TNF-alpha release. Constitutive secretion of IL-1 beta and IL-6 in these patients was already increased to the concentration range of stimulated cells from normal controls and could not be further increased, probably due to maximal in vivo stimulation. Secretion of TNF-alpha, IL-1 beta and IL-6 by peripheral blood monocytes (PBM) and alveolar macrophages from AIDS patients was elevated with or without stimulation compared with normal controls. Obviously, the regulation of TNF-alpha secretion is dependent on the microenvironment. Since it is known that interferon-gamma (IFN-gamma) may induce the production of TNF-alpha, the secretion of this cytokine was examined. Release of IFN-gamma was constitutively and under stimulation lowered in LpMNC from AIDS patients compared with normal controls. Addition of IFN-gamma to LpMNC did not result in enhanced TNF-alpha secretion. Our data indicate a defective function of intestinal mononuclear cells in AIDS patients as shown by the diminished TNF-alpha secretion.

HIV Infections↗
PubMed1993

Autoantibodies in IDDM primarily recognize the 65,000-M(r) rather than the 67,000-M(r) isoform of glutamic acid decarboxylase.

Glutamic acid decarboxylase autoantibodies may aid in rapid screening strategies predicting IDDM before clinical onset. Rat islets contain GAD65 and GAD67 autoantibody targets, but human islets express only GAD65, now confirmed by direct immunoprecipitation from radiolabeled rat and human islets. Because human IDDM involves beta-cell-specific autoimmunity, we tested 190 new IDDM patients and 51 healthy control subjects for antibodies to recombinant human islet GAD65, rat islet GAD67, or human insulinoma/cerebellum GAD67, each expressed separately in hamster fibroblasts. By using immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and densitometric fluorogram scanning, 132 of 190 (70%) of new IDDM patients had GAD65 autoantibodies, whereas only 17 of 190 (9%) had antibodies to rat GAD67 (P < 0.001). Of healthy control subjects, 2 of 51 (3.9%) and 1 of 51 (1.9%) had antibodies to GAD65 and GAD67, respectively. All 17 GAD67 antibody-positive patients also had GAD65 antibodies; 14 of 17 with greater GAD65 than GAD67 index. Control studies showed comparable reactivity between recombinant rat and human GAD67 and between different subcellular preparations of recombinant GAD67 of either species. In conclusion, only GAD65 is expressed in human islets, the autoantibody response is primarily to this isoform, and GAD67 antibodies add little to IDDM detection.

Adolescent↗
PubMed1993

Anti-cardiolipin antibodies (IgG and IgA) in women with recurrent fetal loss correlate to clinical and serological characteristics of SLE.

AIM OF STUDY: We investigated to which degree IgG, IgA and IgM anti-cardiolipin antibodies (aCL) are associated in recurrent abortion or late fetal death with other signs of autoimmune disease and in particular SLE. MATERIAL AND METHODS: Serological variables typical of SLE and of the anti-phospholipid antibody syndrome were measured once eight to 16 weeks after the last fetal loss in 158 women with recurrent abortion or late fetal death; women with manifest autoimmune rheumatic disease were excluded. RESULTS: (1) Positive values, i.e. above the 99th percentile of reference material, of IgG aCL and IgA aCL were observed in 4% and 7%, respectively, whereas 26% had positive values of IgM aCL. (2) IgG aCL and IgA aCL but not IgM aCL correlated to anti-nuclear antibodies and to anti-double stranded DNA. (3) Anti-double stranded DNA, IgG aCL and IgA aCL but not IgM aCL correlated to previous occurrence of thrombosis. (4) ANA correlated to lower blood platelet concentrations and higher erythrocyte sedimentation rates. CONCLUSIONS: Women with recurrent abortion or late fetal death who have higher but not necessarily abnormally high levels of IgG aCL or IgA aCL constitute a group with increased occurrence of clinical and serological characteristics of SLE. We suggest that these women be kept under surveillance for future development of autoimmune disease especially SLE. The women with high IgM aCL constitute another group without these characteristics.

Abortion, Habitual↗
PubMed1993

Specific nitrogen-15 labelling of leucine residues in human growth hormone.

Biosynthetic human growth hormone (hGH) specifically 15N labelled in the leucine residues has been obtained by recombinant DNA technology, using 15N-labelled leucine and an E. coli strain that requires leucine. It is shown that, despite the possibility of minor transaminase activity, the labelling on the whole is specific, and that the two-dimensional 1H-15N correlation NMR spectra of hGH can be greatly simplified by this methodology.

Escherichia coli↗