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Biomedical subjects

O Hoffmann

Publications and source records attributed to O Hoffmann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Hemostatic effects of high-dose megestrol acetate therapy in patients with advanced gynecological cancer.

Effects of high-dose megestrol acetate on blood coagulation and fibrinolysis were investigated in patients with gynecological (n = 13) and breast (n = 10) cancer. Patients received either 160 mg or 320 mg/day megestrol acetate orally. Blood sampling was performed prior to and after months 1, 3 and 6 of treatment. Pretreatment values of global clotting times, fibrinogen, factor VII, thrombin-antithrombin III complex, anticoagulation, fibrinolysis and antifibrinolysis were found to be within the reference range. Elevated plasma levels were demonstrated for prothrombin fragments 1 and 2, fibrin degradation products and the plasmin-antiplasmin complex. We demonstrated a significant 20-30% reduction of factor VII until the 3rd month of therapy. No further effects were seen within the remaining 3 months of treatment. For the other analyzed parameters of hemostasis, no significant influence of high-dose progestin treatment was found. Furthermore, we observed no clinically relevant differences between the two dosages. Our results do not provide any evidence that there is a thrombogenic effect of high-dosage megestrol acetate with 160 mg or 320 mg per day amongst patients with advanced gynecological malignancies. The observed incidence of thrombosis might be the consequence of other risk factors such as tumor-induced hypercoagulability, simultaneous chemotherapy or other individual thrombosis risk factors.

Adult↗
PubMed2000

Adjuvant CMF-chemotherapy and haemostasis. Effect of "classical" and "modified" adjuvant CMF-chemotherapy on blood coagulation fibrinolysis in patients with breast cancer.

Effects of "classical" and "modified" adjuvant CMF-chemotherapy on haemostasis were studied in 22 patients with breast cancer receiving cyclophosphamide (100 mg/m2 p.o.; days 1-14 or 600 mg/m2 i.v.; days 1,8), methotrexate (40 mg/m2 i.v.; days 1,8) and 5-fluorouracil (600 mg/m2 i.v.; days 1,8). Blood collection was done prior to chemotherapy on day 1 and 8. A significant decrease of protein C antigen and activity associated with cumulative effects was observed from day 1 to 8. This effect was similar with "classical" and "modified" CMF-chemotherapy but the reduction of protein C was more pronounced with the oral application of cyclophosphamide. In absence of any significant cumulative decrease of other vitamin K-dependent blood coagulation proteins (factor VII, protein S), the simultaneous decrease of protein C activity and antigen indicates a specific influence of CMF-chemotherapy on vitamin K-dependent protein C-synthesis in the liver.

Administration, Oral↗
PubMed2000

Perioperative development of a thrombogenic risk profile in patients with carcinomas of the breast: a cause of increased thrombosis.

Within the context of a prospective study we investigated the influence of malignant and benign breast disease on the coagulation systems both prior to and after surgery. In addition we also investigated to what extent individual risk factors aid the formation of a thrombophiliac risk profile. Altogether 50 patients with carcinomas of the breast and 12 patients with benign breast disease were included in the study. The coagulation investigations took place prior to surgery and on the 1st, 3rd, 7th and 10th day following the operation. The results have already revealed that prior to surgery a clear activation of the haemostasis takes place among patients with a carcinoma of the breast. When compared to patients with benign breast conditions there was a far greater plasma level of factor VIII vWF, fibrinogen, thrombin-antithrombin III complex, D-dimer fibrin degradation products, tissue-type plasminogen activator and the activity and the antigen of plasminogen activator inhibitor 1. Also during the postoperative period the malignant tumour was a stimulus for additional increased activity of blood coagulation and fibrinolysis. Individual risk factors such as age, menopausal status, obesity and smoking lead to a thrombogenic risk profile which could provide a possible explanation for the observed increased incidence of thrombosis in breast cancer patients. For the clinical work there is a need for intensive pre- and postoperative monitoring in the cases of patients with malignant tumours including angiological examinations, intensive physiotherapy and a risk-adapted prophylactic anticoagulation.

Adult↗
PubMed1999

Genetic differences in the antinociceptive effect of morphine and its potentiation by dextromethorphan in rats.

The effect of the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist dextromethorphan on morphine-induced antinociception was studied with the hot plate test in Sprague-Dawley (SD), Wistar-Kyoto (WK), Spontaneously Hypertensive (SHR) and Dark-Agouti (DA) rats. Subcutaneous morphine at 5 mg/kg induced significant antinociception in all four rats strains. Subcutaneous dextromethorphan at 15 and 45 mg/kg, but not 5 mg/kg, significantly and dose-dependently potentiated morphine-induced antinociception in SDs, WKs and SHRs, but not in DAs. In SHRs and DAs the antinociceptive effect of morphine was followed by prolonged hyperalgesia, which was reduced (SHRs) or abolished (DAs) by dextromethorphan. These results suggest that there are significant differences among rat strains in their response to morphine and in the ability of dextromethorphan to potentiate morphine-induced antinociception. These differences are possibly of genetic origin. Moreover, these data show that morphine, at least in some strains of rats, induced a delayed and NMDA receptor-dependent hyperalgesic response, supporting the notion that administration of opiates may activate NMDA receptors, leading to reduced antinociceptive effect and the development of hyperalgesia.

Animals↗
PubMed1999

Extracellular cholecystokinin levels in the rat spinal cord following chronic morphine exposure: an in vivo microdialysis study.

Conflicting results concerning the issue of whether or not chronic morphine exposure induces an increase in CCK biosynthesis have been found in many CNS sites, including the spinal cord, where CCK activity may contribute to the facilitation of the development of opiate tolerance. The present study was undertaken in order to monitor the extracellular level of CCK under spontaneous and stimulus-evoked release in the spinal cord dorsal horn of drug naive and morphine tolerant rats. Tolerance was induced by implantation of two morphine pellets (2x75 mg) which induced a stable morphine plasma concentration after 48 h post-implantation. The tail-flick test and naloxone precipitated withdrawal were used as indexes of tolerance and dependence to morphine. The effect of morphine-pellet implantation on basal and K+-induced release of CCK-like immunoreactivity (CCK-LI) in the rat dorsal horn were monitored with in vivo microdialysis 96 h after implantation of morphine or placebo pellets, when rats showed tolerance and dependence. Basal CCK levels were below the detection limit of the assay (0.6 pM) in both tolerant and normal animals. K+ (100 mM) in the perfusion medium induced a more than 3-fold increase of the extracellular level of CCK-LI in control animals, and a more than 4-fold increase on CCK-LI in morphine-pellet implanted animals. However, this difference was not significant. In addition, naloxone (2 mg/kg; i.v.), did not induce any change in the extracellular level of CCK in either group. The present study suggests that the modulatory interaction between CCK and opioids in the development of tolerance in the spinal cord may occur without necessarily increasing the extracellular level of CCK. Another possible explanation of the finding is that the microdialysis technique is not sensitive enough to detect differences in unstimulated CCK levels in normal and tolerant animals.

Analgesics, Opioid↗
PubMed1999

Monitoring of venous hemodynamics in patients with cerebral venous thrombosis by transcranial Doppler ultrasound.

OBJECTIVES: To test the assumption that transcranial Doppler ultrasound (TCD) is able to detect and to monitor intracranial venous blood flow velocities in patients with confirmed cerebral venous thrombosis (CVT). DESIGN: Prospective case study in 18 patients. SETTING: Inpatient neurologic service in a university hospital. SUBJECTS AND METHODS: Serial TCD examinations were performed in 18 consecutive patients with CVT (14 females, 4 males) aged 16 to 64 years (mean+/-SD, 36.8+/-13.1 years) during a mean follow-up ranging from 34 to 783 days (mean+/-SD, 201+/-185 days) between 1993 and 1997. Venous TCD was performed with a 2-MHz range-gated transducer. RESULTS: Venous blood flow velocities were successfully measured in all patients. The highest measured velocities in the monitored intracranial venous vessels ranged from 20 to 150 cm/s (mean+/-SD, 58.9+/-38.8 cm/s), and the lowest were from 9 to 84 cm/s (mean+/-SD, 27.9+/-17.0 cm/s). Fifteen patients (83%) showed a decrease of velocities-2 of them after a transient increase during cessation of heparin therapy. The percentage of velocity decrease ranged from 34% to 73% (mean+/-SD, 56.4%+/-10.9%). A plateau phase, defined as no further decrease in velocities, was reached in these patients within 4 to 314 days (mean+/-SD, 59.9+/-73.7 days). Three patients (17%) showed no changes in velocities as defined by a limit of velocity variation of 30% during the course of CVT. High venous velocities were significantly associated with altered consciousness (P = .001). A nonsignificant relationship was observed with affliction of the superior sagittal sinus. No correlations were noted for onset of disease, initial motor deficits, and presence of bleeding. No predictive value was gained from analyzing the outcome in relation to absolute velocities or their decrease. CONCLUSIONS: Serial TCD studies allow monitoring of venous hemodynamics and collateral pathways in patients with CVT. Normal venous velocities in serial measurements, however, do not exclude a diagnosis of CVT.

Adolescent↗
PubMed1999

"De novo" formation of intracranial aneurysms: who is at risk?

Although aneurysms are widely considered to be of congenital origin there is still debate as to whether some at least might be formed de novo during life. A review of all 49 reported cases plus one previously unpublished case reveals common clinical features and might aid in the management of this group of patients. Statistical analysis of all 50 cases of de novo aneurysms discloses a more frequent history of smoking (P = 0.0007) and arterial hypertension (P = 0.0026) than in a control cohort. Patients with de novo aneurysms are younger (P < 0.0001); the proportion with multiple aneurysms was 28 %. Of de novo aneurysms 44 % became symptomatic 3-6 years after the first subarachnoid haemorrhage (SAH), and the interval was significantly shorter in hypertensive patients. We suggest that young patients with a history of SAH and arterial hypertension and nicotine abuse should therefore be considered for conventional angiography after a 5-year interval. MRA might not be useful due to clip artefacts from even nonferromagnetic clips. Close control of blood pressure is essential in these patients.

Adolescent↗
PubMed1999

Treatment of advanced pancreatic cancer with the long-acting somatostatin analogue lanreotide: in vitro and in vivo results.

Fourteen patients with metastatic pancreatic adenocarcinoma were treated with the long-acting somatostatin (SST) analogue lanreotide. No objective response was obtained, and the median survival was 4 months (range 1.8-7 months). Pancreatic cancer could not be visualized by means of SST-receptor (R) scintigraphy in our patients. In vitro data also demonstrated absence of SSTR2 expression, suggesting pancreatic cancer not to be a potential target for treatment with SST analogues.

Adenocarcinoma↗
PubMed1999

The inferior petrosal sinus: assessment by transcranial Doppler ultrasound using the suboccipital approach.

Recently, intracranial veins and sinuses have been successfully insonated using the transtemporal and transoccipital approaches by transcranial Doppler ultrasound. The purpose of this study was to prove the capacity of the Doppler method to evaluate the inferior petrosal sinus via the suboccipital approach. Venous transcranial ultrasound was performed with a range-gated 2-MHz transducer in 80 healthy volunteers and patients without central nervous system disorders ranging in age from 15-84 years (mean +/- standard deviation [SD], 37.6 +/- 15.2 years). A venous signal with a flow directed toward the probe was considered to originate from the inferior petrosal sinus because of its proximity to the basilar artery. The inferior petrosal sinus was insonated in 96.3% of the cases at least on one side. It was found bilaterally in 48 (60%), on the right side in 74 (92.5%), and on the left side in 51 (63.8%) subjects, respectively. Mean blood flow velocity ranged from 8-53 cm/s (mean +/- SD, 19.6 +/- 8.7 cm/s). A significant age dependency of venous velocities was found. Weak but significant side-to-side differences were observed, reflecting the known right-sided predominance of venous outflow in humans. Using the suboccipital approach, the inferior petrosal sinus can be insonated in a high percentage of subjects without major difficulties and is defined by its vicinity to the basilar artery.

Adolescent↗
PubMed1999

Blood flow velocities in the vertebral veins of healthy subjects: a duplex sonographic study.

Along with the jugular veins, the vertebral veins serve as an important pathway for venous blood returning from the brain. In this study, the authors report duplex sonographic findings in 138 healthy subjects without central nervous disease. Successful insonation was possible in 70.7% of all examined vessels. Bilateral insonation was achieved in 86 subjects (62.3%). Only 1 vertebral vein was detected in 23 persons (16.7%), whereas no vein was found in 29 persons (21%). The authors observed a marked variation of peak flow velocities ranged (5-81 cm/s, mean +/- standard deviation, 23.9 +/- 12.3 cm/s). No significant gender-related or side-to-side differences or age influences on flow velocities were detected. The authors' findings may be of relevance when discussing flow velocities in the vertebral veins in cases of cerebrovenous disorders (e.g., dural sinus thrombosis) or in patients after neck dissection.

Adolescent↗
PubMed1999

Analysis of CO2 vasomotor reactivity and vessel diameter changes by simultaneous venous and arterial Doppler recordings.

BACKGROUND AND PURPOSE: The use of flow velocity changes in the middle cerebral artery (MCA) measured by Doppler techniques as an index of corresponding cerebral blood flow (CBF) changes is based on the assumption that the insonated arterial diameter remains stable. The postulate of unchanging vessel calibers during CBF changes, however, is still under debate. We performed simultaneous measurements of arterial and venous blood flow velocities by transcranial Doppler ultrasound during various stages of hypercapnia to analyze diameter changes in the insonated vessels by comparing differences in the vasomotor reactivity. METHODS: Simultaneous Doppler recordings of 1 MCA and of a contralateral venous vessel thought to represent the sphenoparietal sinus (SPS) were carried out with a pair of 2-MHz range-gated transducers in 16 young healthy subjects during variations of end-tidal PaCO2. RESULTS: During hypercapnia the mean blood flow velocity of the MCA rose from 62. 5+/-10.2 to a maximum of 99+/-12.2 cm/s (vasomotor reactivity of 60. 1+/-17.3%). The corresponding values in the SPS were significantly higher (P<0.001), revealing a rise from 17.8+/-5.7 to 34.9+/-14.3 cm/s (vasomotor reactivity of 91.4+/-25.9%). Exponential and linear regression analyses revealed an identical high correlation (r2=0.97 and 0.98 for the MCA and SPS, respectively). Slopes were 0.034+/-0. 01 on the arterial and 0.048+/-0.01 on the venous side. The CO2 reactivity (percentage per mm Hg, EtCO2) was found to be 4.5+/-1%/mm Hg in the MCA and 6.8+/-1.5%/mm Hg in the SPS. This difference indicates a vasodilation of the MCA in comparison to the venous vessel. CONCLUSIONS: We have demonstrated a different reaction pattern between intracranial venous and arterial vessels related to end-tidal CO2. Relating the flow velocities to the square of the vessel diameter and assuming a global rise of CBF and not extensible sinus walls, our results indicate that the MCA undergoes a vasodilation of 9.5+/-7% in maximal hypercapnia.

Adult↗
PubMed1999

Resveratrol pretreatment desensitizes AHTO-7 human osteoblasts to growth stimulation in response to carcinoma cell supernatants.

Resveratrol, a natural phytoestrogen, has been reported to promote differentiation of murine MC3T3-E1 osteoblasts and to inhibit proliferation of prostate cancer cell lines. In the present study we tested the effects of resveratrol on the increased proliferation of human AHTO-7 osteoblastic cell line induced by conditioned media (CM) from a panel of carcinoma cell lines. This compound was found to modulate AHTO-7 proliferation in a tamoxifen-sensitive mechanism at lower concentrations, but failed to induce the osteoblast differentiation marker alkaline phosphatase (ALP) in contrast to vitamin D3. The proliferative response of AHTO-7 cells to conditioned media from carcinoma cell lines was diminished (30-71.4% inhibition) upon pretreatment with 0.5 microM resveratrol. Highest inhibition was demonstrated for pancreas (BxPC3, Panc-1), breast (ZR75-1) and renal (ACHN) carcinoma cell line supernatants whereas the effect on colon carcinoma (SW620, Colo320DM) cell CM and prostate cancer (PC3, DU145 and LNCaP) CM was less pronounced. Direct addition of resveratrol affected only supernatants of cell lines (<25% inhibition) exhibiting growth stimulatory activity for normal WI-38 lung fibroblasts. Resveratrol inhibited proliferation of DU145 and LNCaP cells in concentrations exceeding 5 microM, altered cell cycle distribution of all prostate cancer cell lines in concentrations as low as 0.5 microM, but did not inhibit the production of osteoblastic factors by these lines. In conclusion, resveratrol failed to induce ALP activity as marker of osteoblast differentiation in human osteoblastic AHTO-7 cells, however, inhibited their response to osteoblastic carcinoma-derived growth factors in concentrations significantly lower than those to reduce growth of cancer cells, thus effectively modulating tumor - osteoblast interaction.

Alkaline Phosphatase↗
PubMed1998

Genetic differences in morphine sensitivity, tolerance and withdrawal in rats.

Significant genetic differences in the endogenous opioid system and in response to a variety of noxious stimuli are present in rodents. We now compared the response to noxious heat with the hot plate test, morphine sensitivity and the development of tolerance and dependence to morphine in spontaneously hypertensive (SHR), Wistar-Kyoto (WK) and Sprague-Dawley (SD) rats. Significant differences were observed in basal nociception among the three strains, where SHRs were hypoalgesic compared to WK and SD. The antinociceptive effect of morphine varied among strains (SD>SHR>WK) as did the rate of tolerance development (10 mg/kg morphine 2/day for 4 days) where WK>SD=SHR. SHR rats developed hyperalgesia following morphine administration during the course of tolerance development. Furthermore, although naloxone (2 mg/kg) precipitated withdrawal symptoms in all tolerant rats, the panorama of symptoms varied among the three strains. Thus, there are significant genetic differences in a variety of effect of opiates.

Animals↗
PubMed1998

Interaction of triiodothyronine with 1alpha,25-dihydroxyvitamin D3 on interleukin-6-dependent osteoclast-like cell formation in mouse bone marrow cell cultures.

In mouse bone marrow cultures, the formation of osteoclast-like, that is, tartrate-resistant acid phosphatase-positive (TRAP+) and calcitonin (CT) receptor-positive multinucleated cells (MNCs), induced by 10(-10) to 10(-8) mol/L 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], could be augmented by triiodothyronine (T3), which alone had no effect on osteoclast-like cell formation. The permissive effect of T3 increased the response to 1alpha,25(OH)2D3 by approximately one order of magnitude. Linear concentration dependence was observed between 10(-11) and 10(-8) mol/L T3. Importantly, inhibition of prostaglandin synthesis by indomethacin significantly impeded osteoclast-like cell formation by 1alpha,25(OH)2D3 and abrogated the effect of T3 thereon. Basal interleukin-6 (IL-6) production by cultured marrow cells was significantly stimulated by 1alpha,25(OH)2D3. However, even at an exceedingly high concentration of 20 ng/mL, IL-6 was ineffective in inducing osteoclast-like cell formation. Therefore, any hormonally induced rise in IL-6 release from bone marrow cells could not account for the observed changes in TRAP+ MNC numbers. Nevertheless, the stimulatory effect of 1alpha,25(OH)2D3 on osteoclastogenesis was partially dependent on IL-6 because it could be significantly blocked by a neutralizing monoclonal anti-IL-6 antibody, and to the same extent by a monoclonal anti-IL-6 receptor antibody. Unimpaired signaling through the IL-6/IL-6R system is also a prerequisite for the auxiliary effect of T3 on induction of osteoclast-like cells by 1alpha,25(OH)2D3. Our data provide evidence that 1alpha,25(OH)2D3 induces osteoclast-like cell formation, at least in part, in an IL-6-dependent mode of action, which is also subject to modulation by T3. The mechanism of interaction of the two hormones apparently involves joint stimulation of prostaglandin synthesis.

Acid Phosphatase↗
PubMed1998

Adjuvant antiestrogen treatment with tamoxifen in postmenopausal women with breast cancer: a longitudinal study of blood coagulation and fibrinolysis.

Potential effects of tamoxifen therapy on blood coagulation and fibrinolysis were investigated in women with breast cancer. We studied 14 parameters of hemostasis in 19 postmenopausal women receiving 20 mg tamoxifen/day as an adjuvant treatment. Blood sampling was done before and after the 1st, 3rd, and 6th month of treatment. Pretreatment values of procoagulation, anticoagulation, plasminogen, and plasminogen activator inhibitor were found within the reference range, whereas tissue-plasminogen activator, fibrin degradation products, and prothrombin-fragment 1+2 were elevated. On therapy an initial decrease of all measured parameters was observed. The effect was pronounced in coagulation inhibitors (antithrombin III, protein C and S). No pathological values (below 60%) were observed. No further effects were found during the 3rd and 6th month of treatment. Our data indicate that the decrease of hemostatic parameters during the initial phase of tamoxifen treatment is due to the timing of blood collection, which took place no more than 14 days after surgery. The reduction of coagulation inhibitors was not associated with pathological values. No cumulative effects were seen during tamoxifen therapy. The decrease was not associated with a concomittant increase of in vivo coagulation markers (prothrombin-fragment 1+2, thrombin-antithrombin-complex, fibrin degradation products). Therefore our results are likely to reflect only the resolution of postoperative activation and do not translate into a drug related thrombogenic effect.

Aged↗
PubMed1997

Rescue of osteoclast function by transgenic expression of kinase-deficient Src in src-/- mutant mice.

The Src tyrosine kinase has been implicated in a wide variety of signal transduction pathways, yet despite the nearly ubiquitous expression of c-src, src-/- mice show only one major phenotype-osteopetrosis caused by an intrinsic defect in osteoclasts, the cells responsible for resorbing bone. To explore further the role of Src both in osteoclasts and other cell types, we have generated transgenic mice that express the wild-type and mutated versions of the chicken c-src proto-oncogene from the promoter of tartrate resistant acid phosphatase (TRAP), a gene that is expressed highly in osteoclasts. We demonstrate here that expression of a wild-type transgene in only a limited number of tissues can fully rescue the src-/- phenotype. Surprisingly, expression of kinase-defective alleles of c-src also reduces osteopetrosis in src-/- animals and partially rescues a defect in cytoskeletal organization observed in src-/- osteoclasts. These results suggest that there are essential kinase-independent functions for Src in vivo. Biochemical examination of osteoclasts from these mice suggest that Src may function in part by recruiting or activating other tyrosine kinases.

Acid Phosphatase↗