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Biomedical subjects

M Haag

Publications and source records attributed to M Haag.

At least 19 recordsLinked to original sources
PubMed2007

Challenges and perspectives of computer-assisted instruction in medical education: lessons learned from seven years of experience with the CAMPUS system.

OBJECTIVES: In this paper we discuss solutions to the problem that medical teachers and students do not use modern computer-assisted instruction systems in medical education as much as expected by their developers. METHODS: As an example for a modern problem-based CAI system we introduce the CAMPUS shell system for case-based training in medicine. RESULTS: CAMPUS has received several awards and positive evaluation results. Nevertheless, the usage of such systems in courses and for self-study could be increased. CONCLUSIONS: Curricular integration of CAI as well as further improvements on existing CAI systems to increase the usage in medical education is essential.

Case-Control Studies↗
PubMed2006

Effects of arachidonic acid, docosahexaenoic acid and prostaglandin E(2) on cell proliferation and morphology of MG-63 and MC3T3-E1 osteoblast-like cells.

During bone remodelling bone is resorbed by osteoclasts and replaced again by osteoblasts through the process of bone formation. Clinical trials and in vivo animal studies suggest that specific polyunsaturated fatty acids (PUFAs) might benefit bone health. As the number of functional osteoblasts is important for bone formation the effects of specific PUFAs on in vitro osteoblastic cell proliferation were investigated. Morphological studies were conducted to determine whether exposure of the cells to these agents caused structural damage to the cells thereby yielding invalid results. Results from this study showed that arachidonic acid (AA) and docosahexaenoic acid (DHA) both inhibit cell growth significantly at high concentrations. The anti-mitotic effect of AA is possibly independent of PGE(2) production, as PGE(2) per se had little effect on proliferation. Further study is required to determine whether reduced proliferation due to fatty acids could be due to increased differentiation of osteoblasts to the mature mineralising osteoblastic phenotype.

Animals↗
PubMed2006

High-power, longitudinally fiber-pumped, passively Q-switched Nd:YAG oscillator-amplifier.

A longitudinally fiber-pumped, passively Q-switched Nd:YAG laser oscillator-power amplifier system is reported with which a maximum pulse energy of 68 mJ was achieved at high pulse stability, beam quality, and efficiency. Therefore, a compact fiber-coupling interface was developed for stacked arrays of quasi-cw diode lasers, providing a pump power of 1 kW at the fiber end.

Journal Article↗
PubMed2005

Stimulation of prostaglandin E2 (PGE2) production by arachidonic acid, oestrogen and parathyroid hormone in MG-63 and MC3T3-E1 osteoblast-like cells.

Polyunsaturated fatty acids (PUFAs) as well as oestrogen (E2) and parathyroid hormone (PTH) affect bone cells. The aim of the study was to determine whether arachidonic acid (AA), E2, and PTH increase prostaglandin E(2) (PGE(2)) synthesis in MG-63 and MC3T3-E1 osteoblastic cells and the level of mediation by COX-1 and COX-2. PGE(2) levels were determined in the conditioned culture media of MG-63 and MC3T3-E1 osteoblasts after exposure to AA, PTH and E2. Cells were pre-incubated in some experiments with the unselective COX inhibitor indomethacin or the COX-2 specific blocker NS-398. Indirect immunofluorescence was performed on MG-63 cells to detect the presence and location of the two enzymes involved. AA increased PGE(2) secretion in both cell lines; production by MC3T3-E1 cells, however, was significantly higher than that of MG-63 cells. This could be due to autoamplification via the EP(1) subtype of PGE receptors in mouse MC3T3-E1 osteoblasts. Both COX-1 and COX-2 affected the regulation of PGE(2) synthesis in MG-63 cells. E2 had no effect on PGE(2) secretion in both cell lines, while PTH caused a slight increase in PGE(2) synthesis in the MG-63 cell line.

Animals↗
PubMed2004

[The evaluation of balloonkyphoplasty for osteoporotic vertebral fractures. An interdisciplinary concept].

BACKGROUND DATA: Patients with osteoporotic vertebral compression fractures frequently complain of pain and a loss of function and mobility. Such fractures are associated with an increased mortality. The common treatment with bed rest, bracing or osteosynthesis does not lead to satisfying results. With two new surgical techniques, vertebroplasty and kyphoplasty, an internal stabilisation of osteoporotic vertebral fractures is possible. METHODS: All patients were treated by kyphoplasty. With a minimal invasive dorsal approach, an inflatable bone tamp is placed in the fractured vertebral body. This tamp can restore the vertebral body height and create a cavity, which is filled with bone cement under low pressure. The advantage of kyphoplasty compared to vertebroplasty is the restoration of the vertebral height and a decreased cement leakage rate. We performed a prospective, interdisciplinary study with a follow-up of 12 months. We treated 192 vertebral fractures in 102 patients. Augmentation was performed with polymethylmethacrylate in 138 cases and with a new injectable calcium phosphate-cement in 54 vertebral bodies. Outcome data were obtained with two different spine-scores and by the radiomorphometric evaluation of x-rays before and after treatment. RESULTS: We noticed a significant improvement in pain and function in 89% of the patients. All patients showed a regain of vertebral height of on average 17%. In 7% of all treated vertebral bodies, we noticed cement leakage, which was, however, far below the rates published for vertebroplasty (20-70%). There were two complications, bleeding due to an unknown coagulopathy and a violation of the myelon by malpunction. CONCLUSION: Kyphoplasty is a reliable and minimally invasive method for stabilizing fractured osteoporotic vertebral bodies. Improvement of pain and function and a regain in height of the treated vertebral body can be accomplished.

Aged↗
PubMed2004

Skeletal metastasis in tricholemmal carcinoma.

Tricholemmal carcinoma is an extremely rare cutaneous adnexal tumor, not exceeding 1-2 cm in diameter in some reported cases. The few reports describe only a greater histologic malignancy. Some cases of recurrences have been reported, and metastasis of the soft tissue was described once by Amaral et al in 1984. In the current patient with tricholemmal carcinoma of the right distal thigh, the primary tumor was unusually large. The first detected metastasis was localized in the right inguinal lymph nodes. Five years after diagnosis of tricholemmal carcinoma a metastasis of the left tibia and fibula were diagnosed. To our knowledge, an osseous metastasis in tricholemmal carcinoma has not been described. It is possible that a relationship between the extraordinary size and the osseous metastasis exists in the current patient.

Bone Neoplasms↗
PubMed2002

[Patient with skeletal metastases. Mobile despite destroyed bones].

Bone metastases endanger both the mobility of the cancer patient and his ability to profit from medical/nursing care. Treatment aims to prevent fractures of the long bones and vertebrae and to avoid neurological defects caused by compression of the spinal cord. Treatment is indicated when the following criteria are met: for the long bones a defect measuring more than 2.5 cm in length or affecting more than 50% of the circumference; for the vertebrae destruction of more than 60%. Almost all patients require radiotherapy, with a minority also needing surgical treatment in the form of intralesional tumor resection, closure of the defect with bone cement, and the use of metal implants.

Bone Neoplasms↗
PubMed2002

[Eikenella corrodens-induced spondylitis. Detection with 16s-RNA polymerase chain reaction].

Isolation of the relevant organism in patients with spondylitis even after an open biopsy is successful only in 75-90%. The rare case of an Eikenella corrodens-induced spondylitis is presented, which could only be identified using 16S ribosomal DNA polymerase chain reaction following unsuccessful microbiological cultivation. Eikenella corrodens is a facultative anaerobic gram-negative organism, which is mostly found in the oropharynx of healthy patients.

DNA, Bacterial↗
PubMed2002

The effect of omega-3 fatty acids on Ca-ATPase in rat cerebral cortex.

Neuronal Ca-ATPase has the essential function of keeping intracellular Ca levels in the micromolar range. This is a prerequisite for normal neurotransmission. This study was designed to determine whether Ca-ATPase is a target for docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) action: results show that both these fatty acids are inhibitors of Ca-ATPase activity in synaptosomal membranes isolated from rat cerebral cortex (-65+/-5% at [DHA]=20 microg/ml, -59+/-7% at [EPA]=20 microg/ml). The inhibition caused by EPA, but not that of DHA, could be reversed completely by the addition of calphostin, a protein kinase C blocker. In contrast, DHA could stimulate Ca-ATPase activity (+132+/-5% at [DHA]=30 microg/ml) only in calmodulin-depleted membranes. In addition, Na,K-ATPase (which drives the Na-Ca exchanger) was inhibited by both DHA and EPA, both at 30 microg/ml (-15+/-0.7% and -42+/-1%, respectively). These results suggest a mechanism that explains the dampening effect of omega-3 fatty acids on neuronal activity.

Animals↗
PubMed2002

Canine status epilepticus: a retrospective study of 50 cases.

The medical records of 50 dogs that exhibited generalised convulsive tonic-clonic (GCTC) status epilepticus (SE) were reviewed and compared with the records of 50 dogs that exhibited non-SE GCTC seizures. The mean age, bodyweight and gender of the patients in both groups were not significantly different. Dogs in the non-SE group were two times more likely to be an idiopathic epileptic than to have secondary epileptic seizures. The SE group was more likely to have abnormalities on cerebrospinal fluid analysis, but not more likely to have abnormalities detected on computed tomography, when compared with the non-SE group. SE was 1.57 times more likely if the cause for the seizures was secondary or reactive epilepsy rather than idiopathic or primary epilepsy. In conclusion, dogs that exhibit SE should be thoroughly investigated for secondary causes.

Age Factors↗
PubMed2001

Effect of arachidonic acid on duodenal enterocyte ATPases.

Duodenal ion transport processes are supported by ATPase enzymes in basolateral membranes of the enterocyte. In vivo studies have shown that long term n-6 poly-unsaturated fatty acid (PUFA) supplementation in rats causes increases in intestinal Ca absorption, coupled with a higher total calcium balance and bone calcium content. The present in vitro study was undertaken to test the effect of arachidonic acid (AA), a highly unsaturated (and thus physiologically potent) member of the n-6 PUFA family, on ATPases in enterocyte basolateral membranes isolated with a sorbitol density gradient procedure. This paper presents results which show that AA inhibits Na+,K+-ATPase in a dose-dependent manner (-67% of basal activity at a concentration of 30 microg/ml, P < 0.005) but that this effect is not mediated by protein kinase C, as shown by the use of the protein kinase C blocker calphostin (0.5 microM). Indomethacin (IDM) at 0.1 mM, a cyclo-oxygenase blocker, could also not reverse the inhibitory effect of AA on Na+,K+-ATPase. Ca2+-ATPase, on the other hand, is not affected significantly (-10%, P > 0.05) by arachidonic acid at 30 microg/ml.

Animals↗
PubMed2001

Altered expression of lung cytochrome P450 3A1 in rat after exposure to sulfur mustard.

Expression of cytochromes P450 (CYP) and glutathione S-transferases in the lung may be affected by inhaled pollutants. We have investigated the effect of sulfur mustard on the expression of CYP 1A1, 2B1, 2E1 and 3A1, as well as of alpha-, micro- and pi-glutathione S-transferases in rat lung. Sulfur mustard (0.025, 0.05 or 0.1 mg/kg) or its vehicle was administered to anaesthetized animals by intratracheal injection. Expression of CYP and glutathione S-transferases was analysed 24 hr after administration of the vesicant warfare using western blotting. Preservation of airway epithelium integrity after animal exposure to sulfur mustard was confirmed by histological examination of tracheal and lung tissues from control and treated animals. Constitutive levels of CYP 2B1 and 3A1 proteins were found in lung tissue from control rats, whereas CYP 1A1 and 2E1 proteins were not detected. Animal exposure to sulfur mustard enhanced CYP 3A1 protein levels by 80 to 103%. In contrast, exposure to sulfur mustard neither modified CYP 2B1 expression, nor led to detectable expression of CYP 1A1 or 2E1. Constitutive levels of alpha-, micro- and pi-glutathione S-transferase proteins were found in lung tissue from control rats. Exposure to sulfur mustard had no effect on expression of either of the glutathione S-transferases. Our results show that intratracheal exposure to sulfur mustard selectively increases CYP 3A1 expression in rat lung. Taking into account the major role of CYP of the 3A family in the metabolism of drugs, up-regulation of CYP 3A1 by sulfur mustard might have important therapeutic consequences.

Animals↗
PubMed2001

Upregulation of duodenal calcium absorption by poly-unsaturated fatty acids: events at the basolateral membrane.

Poly-unsaturated fatty acids, especially of the n-3 series, have a beneficial effect in treatment of osteoporosis in the elderly. Duodenal calcium absorption is a particularly vulnerable aspect of the development of this disease. It has been shown that the process of calcium transport through the rat duodenal enterocyte takes place in essentially three steps: entry of calcium through channels in the brush border (apical membrane), transcellular transport through the cytoplasm by calbindin and extrusion at the basolateral membrane by Ca(2+)-ATPase and a Ca(2+)-Na(+)exchanger which is driven by Na(+), K(+)-ATPase. This paper presents a hypothesis that poly-unsaturated fatty acids can modulate both Ca(2+)-ATPase and Na(+), K(+)-ATPase activity either by a direct action on the enzyme or by phosphorylation processes via protein kinases A and C and thus exert their positive influence on calcium absorption in this manner.

Animals↗
PubMed2001

Modulation of intestinal vitamin D receptor availability and calcium ATPase activity by essential fatty acids.

The physiological mechanisms by which essential fatty acids (EFAs) affect calcium (Ca(2+)) retention is not clear, but suggestions have included changes in membrane fluidity, receptor modulation and induction of second messengers. The vitamin D receptor (VDR) is essential for the functioning of 1,25(OH)(2)D(3)which increases Ca(2+)absorption. Activity of the intestinal basolateral membrane (BLM) Ca(2+)ATPase correlates with the degree of Ca(2+)absorption. Therefore, changes in ATPase activity and VDR availability due to EFAs may influence calcium retention. We have investigated the effect of long-term dietary supplementation with EFAs on Ca(2+)ATPase activity (measured colourimetrically) and VDR availability (measured with the ELISA technique) after the loss of oestrogen induced by ovariectomy (OVX) in female Sprague Dawley rats. Control animals underwent anaesthesia and a surgical procedure but the ovaries were left intact (sham). Ca(2+)ATPase activity was significantly lower in OVX animals than in the intact animals (P<0.05) and following supplementation with EFAs, was significantly higher than in sham controls (P<0.05). A higher number of VDR was measured after OVX and declined due to EFA supplementation; these differences in activity of the ATPase and number of receptors could be ascribed to membrane changes due to EFA supplementation, feedback control by serum calcium or the direct influence of the EFAs.

Animals↗
PubMed2000

[Juxtaglomerular cell tumor (reninoma) as the etiology of severe juvenile hypertension].

HISTORY AND CLINICAL FINDINGS: A 20-year-old asymptomatic man was admitted with severe hypertension (250/150 mm Hg). Clinical examination was normal. INVESTIGATIONS: Laboratory findings showed hypokalemia and secondary hyperaldosteronism. Abdominal ultrasound and CT-scan revealed an about 2.5 cm measuring tumor of the left kidney. TREATMENT AND COURSE: Under antihypertensive treatment, a normal blood pressure profile could be achieved. With the diagnosis of a reninoma the patient was transferred to the urology department for tumor resection. In a 3-month follow-up the patient was normotensive without any medication. CONCLUSION: Renin-secreting juxtaglomerular tumor of the kidney (reninoma) is a very rare but curable cause of severe hypertension. The syndrome of "primary hyperreninism" is characterized by severe hypertension, hypokalemia, secondary hyperaldosteronism and a renal mass in sonography.

Adenocarcinoma↗
PubMed2000

Act1, an NF-kappa B-activating protein.

Use of an NF-kappaB-dependent selectable marker facilitated the isolation of a cell line containing a cDNA encoding Act1, an NF-kappaB activator. Act1 associates with and activates IkappaB kinase (IKK), leading to the liberation of NF-kappaB from its complex with IkappaB. Many signaling pathways that liberate NF-kappaB also activate activating transcription factor (ATF) and activator protein 1 (AP-1) through Jun kinase (JNK). Act1 also activates JNK, suggesting that it might be part of a multifunctional complex involved in the activation of both NF-kappaB and JNK. Act1 fails to activate NF-kappaB in an IL-1-unresponsive mutant cell line in which all known signaling components are present, suggesting that it interacts with an unknown component in IL-1 signaling.

Adaptor Proteins, Signal Transducing↗
PubMed2000

[Reninoma: a rare cause of hypertension. Case report, review of the literature and possibility for organ preserving operation].

A 20-year-old man with no past medical history and no clinical symptoms was referred for examination because of severe hypertension. The blood chemistry studies showed elevated levels of peripheral renin with evidence of secondary aldosteronism. Sonography and computed tomography demonstrated a mass of the left kidney. After excluding all other possible causes for severe hypertension, excision of the tumor was performed. Histological studies confirmed the diagnosis of a juxtaglomerular cell tumor. Reninoma represents a rare but surgically curable cause of hypertension. The clinical suspicion of this tumor is very important because of the young age of the patients. If the diagnosis is confirmed a renal sparing surgery should be the treatment of choice.

Adenocarcinoma↗