Prognostic Relevance of Circulating Tumor Cells in Molecular Subtypes of Breast Cancer.

Circulating tumor cells (CTCs) can be detected in the peripheral blood of breast cancer patients with early and metastatic disease. Recent data suggest that immune pathologic characteristics between the primary tumor, metastatic colonies and CTCs are discordant and that CTCs possess an independent phenotype that is associated with prognosis and treatment efficacy. Large scale gene expression analysis has provided the possibility to stratify breast cancer according to the gene expression fingerprint of primary tumor tissue into five intrinsic molecular subtypes which can be associated with different clinical outcome. As a consequence of the different prognostic power of primary tumors' characteristics and CTCs several groups have started to investigate if CTCs might be disseminated differentially within these breast cancer subtypes. They determined the CTC number in immunohistochemical subtypes to validate if CTCs may provide differential and more specific prognostic information within each subtype. This review provides an overview of the outcome of some recently published data gathered from early and metastatic breast cancer.

Progestogens and membrane-initiated effects on the proliferation of human breast cancer cells.

OBJECTIVES: Evidence is accumulating that progestogens may play a crucial role in the development of breast cancer under contraception and hormone therapy in reproductive and menopausal women. Progesterone receptor membrane component 1 (PGRMC1) expressed in breast cancer may be important in tumorigenesis and thus may increase breast cancer risk. The aim of this project was to investigate the influence of progesterone and nine synthetic progestins on MCF-7 breast cancer cells overexpressing PGRMC1. METHODS: MCF-7 cells were stably transfected with PGRMC1 expression plasmid (WT-12). To test the effects of progestogerone (P) and the synthetic progestins chlormadinone acetate (CMA), desogestrel (DSG), drospirenone (DRSP), dydrogesterone (DYD), levonorgestrel (LNG), medroxyprogesterone acetate (MPA), nomegestrol (NOM) and norethisterone (NET) on cell proliferation, MCF-7 and WT-12 cells were stimulated with different concentrations (0.01-1 µmol/l). RESULTS: In MCF-7 cells, DRSP, DSG, DYD, LNG and NET increased the proliferation at 1 µmol/l, the effect being highest for NET with about 20%. In WT-12 cells, the same progestins, but additionally MPA, showed a significant increase, which was much higher (30-245%) than in MCF-7 cells. Here again, NET showed the highest proliferative effect. No effect was found for CMA, NOM and P. CONCLUSION: Some synthetic progestins trigger a proliferative response of PGRMC1-overexpressed MCF-7 cancer cells. The effect of progestogens on breast cancer tumorigenesis may clearly depend on the specific pharmacology of the various synthetic progestins.

Circulating Tumor Cells in Early-Stage Breast Cancer.

Disseminated tumor cells (DTC) are routinely detected in bone marrow (BM) in 30-40 % of primary breast cancer patients. Positive BM status at the time of diagnosis as well as DTC persistence after therapy are strong independent prognostic factors. Since repeated BM aspirations are not well tolerated, detection of single tumor cells in peripheral blood (circulating tumor cells; CTC) have become of interest in recent years. CTC are found in 10-80 % breast cancer patients. Variability can be explained by stage of the disease and detection method. Emerging data have shown CTC to be of prognostic relevance for both, patients with primary and metastatic disease. The assessment of CTC in blood may become an important biomarker for prognostication and therapy monitoring. Determination of their molecular characteristics will enable specific targeting of minimal residual as well as metastatic disease. This review summarizes recent research and future perspectives.

Sevoflurane potentiates and blocks GABA-induced currents through recombinant alpha1beta2gamma2 GABAA receptors: implications for an enhanced GABAergic transmission.

BACKGROUND AND OBJECTIVE: The gamma-aminobutyric acidA receptor (GABAAR) is a target for anaesthetic agents. We investigated the interactions of sevoflurane with a recombinant GABAAR. Emphasis was on the mechanism of block, as relevant open-channel block by a volatile anaesthetic would possibly explain prolonged GABAergic postsynaptic currents. METHODS: The effect of sevoflurane on GABA-induced currents through recombinant alpha1beta2gamma2 GABAAR channels was studied (patch clamp; HEK293 cells). GABA 0.01 mM or 1 mM was applied alone or together with sevoflurane (0.05 mM to 5 mM). RESULTS: Currents elicited by GABA 0.01 mM were increased by low sevoflurane concentrations to 183% and decreased by high sevoflurane concentrations (> 1 mM) to 34% (P < 0.05). Ten- to 90%-rise times of the currents were reduced by sevoflurane concentration dependently. At GABA (1 mM), peak currents and 10-90%-rise times decreased with increasing sevoflurane concentrations. A transient current increase was induced by discontinuation of GABA and sevoflurane. Such rebound currents indicate a reversal of an open-channel block by sevoflurane. CONCLUSIONS: Sevoflurane (a) increases the apparent affinity of GABA to the GABAAR, as suggested by the decreased current rise times. This explains the enhancement of the currents induced by low GABA concentrations (0.01 mM). Additionally, sevoflurane (b) induces a picrotoxin-like open-channel block at the GABAAR. The reversal of the open-channel block elicits a delayed GABA response. These findings indicate at least two different sites of action of sevoflurane at this receptor that are both important for an enhanced GABAergic synaptic transmission.

Open channel and competitive block of nicotinic receptors by pancuronium and atracurium.

Mouse myotubes were used to investigate effects of the nondepolarizing neuromuscular blocking drugs pancuronium and atracurium on embryonic-type nicotinic acetylcholine receptor channels. Experiments were performed using patch-clamp techniques in combination with devices for ultra-fast solution exchange at outside--out patches. Application of 0.1 mM acetylcholine resulted in a fast current transient. When the peak amplitude was achieved, the current decayed monoexponentially due to desensitization. After application of drugs (pancuronium or atracurium), two different mechanisms of block were observed: (1) open channel block of embryonic-type nicotinic acetylcholine receptor channels after coapplication of blocker and acetylcholine, characterized by decrease of the time constant of current decay; (2) competitive block of embryonic-type nicotinic acetylcholine receptor channels by pancuronium or atracurium after preincubation of outside-out patches with the respective blocker. Different affinities of pancuronium (K(B) approximately 0.01 microM) and atracurium (K(B) approximately 1 microM) to embryonic-type nicotinic acetylcholine receptor channels were observed.

Nitrous oxide and xenon increase the efficacy of GABA at recombinant mammalian GABA(A) receptors.

We investigated the interactions between recombinant gamma-aminobutyric acid receptor complex (GABA(A)R) and nitrous oxide (N(2)O) or xenon (Xe). Human embryonic kidney cells (HEK 293) were transfected with rat cDNA for alpha(1)beta(2)gamma(2L) or for alpha(1)beta(2) recombinant GABA(A)R subunits. Patch clamp techniques were used in the whole-cell mode to evaluate the effect of N(2)O and Xe on GABA-induced currents. A piezo-driven "liquid filament switch" was used for fast application. Both N(2)O (100%, 29.2 mM) and Xe (100%, 3.9 mM) reversibly increased GABA-induced currents through the alpha(1)ss(2)gamma(2L) and the alpha(1)beta(2) GABA(A)R channels. The potentiating effect of N(2)O or Xe on peak currents was prominent at small GABA concentrations (10(-7) to 10(-5) M). The addition of N(2)O or Xe increased the efficacy of GABA (10(-7) to 10(-3) M). Both N(2)O and Xe significantly decreased the risetime((10%-90%)) of the currents elicited by small GABA concentrations. At the concentrations used, neither N(2)O nor Xe had an intrinsic effect. We conclude that, similar to other anesthetics, both N(2)O and Xe increase the efficacy of GABA at the GABA(A)R and enhance inhibitory GABAergic synaptic transmission.

Dual action of isoflurane on the gamma-aminobutyric acid (GABA)-mediated currents through recombinant alpha(1)beta(2)gamma(2L)-GABA(A)-receptor channels.

Isoflurane (ISO) increased the agonist-induced chloride flux through the gamma-aminobutyric acid A receptor (GABA(A)R). This may reflect an anesthetic-induced increase in the apparent agonist affinity. A dual effect of anesthetics was postulated for both the nicotinic acetylcholine receptor (nAChR) and the GABA(A)R. We tested the hypothesis that, in addition to a blocking effect, ISO increases gamma-aminobutyric acid (GABA)-gated currents through recombinant GABA(A)R channels. HEK293 cells were transfected with rat cDNA for alpha(1),beta(2),gamma(2L) subunits. Currents elicited by 1 mM or 0. 01 mM GABA, respectively, alone, or with increasing concentrations of ISO, were recorded by using standard patch clamp techniques. ISO reduced the peak current elicited by 1 mM GABA. Currents induced by 0.01 mM GABA were potentiated by small ISO (twofold at 0.5 mM ISO) and inhibited by larger concentrations. Withdrawal of ISO and GABA induced rebound currents, suggesting an open-channel block by ISO. These currents increased with increasing concentrations of ISO. At large concentrations of ISO, the inhibitory effect predominated and was caused by, at least partly, an open-channel block. At small concentrations of ISO, potentiation of the GABA-gated currents was more prominent. This dual action of ISO indicates different binding sites at the GABA(A)R. The balance between potentiation and block depends on the concentrations of both ISO and GABA.

Acid aspiration prophylaxis and caesarean section.

Acid aspiration syndrome still contributes to the few anaesthesia-related deaths in caesarean section. Although none of the numerous measures intended to prevent such fatalities is based on clear evidence, many different regimens are being used. As obstetric acid aspiration syndrome occurs mainly in general anaesthesia, using regional techniques wherever possible may be the most effective prophylactic measure.

[Prophylaxis against obstetric acid aspiration syndrome in the German Federal Republic in 1997. A review based on results of a federal survey]. / Prophylaxe des geburtshilflichen Säureaspirationssyndroms in der Bundesrepublik Deutschland 1997. Eine Bestandsaufnahme anhand der Ergebnisse einer bundesweiten Umfrage.

A survey of all German hospitals providing obstetric anesthesia was performed in 1997 (n = 1061, recovery rate 82%; comprising about 700,000 deliveries and 115,000 cesareans, resp.) concerning the routine prophylactic measures for acid aspiration syndrome (AAS) in pregnant patients and before obstetric procedures (i.e., prevention of aspiration by positioning, Sellick's manoeuvre, reduction of intragastric volume, or reduction of gastric content acidity). In pregnant patients, any prophylaxis of AAS is performed in 36%. Of the patients expecting delivery in the labour ward, only 7% receive pharmacological AAS treatment. Before scheduled (urgent, non-emergency) cesarean section in general anesthesia, 93% (94%) of patients receive prophylactic treatment, either pharmacological or non-pharmacological. Before regional anesthesia, the corresponding numbers are 52% for both scheduled or urgent CS.

Cerebral blood flow velocity and carbon dioxide vasoreactivity during gamma-hydroxybutyrate/fentanyl anaesthesia in non-neurosurgical patients.

In this study the effects of gamma-hydroxybutyrate/fentanyl on cerebral blood flow velocity (CBFV) (as measured in the middle cerebral artery by transcranial Doppler ultrasonography) and on cerebrovascular carbon dioxide reactivity were investigated. Mean CBFV (Vmean) and haemodynamic responses were recorded in 12 non-neurosurgical patients before, during and after induction of general anaesthesia with gamma-hydroxybutyrate (GHB) (20 min constant rate infusion of 100 mg kg-1). Two patients were excluded, one because of bradycardia and the other because of severe myoclonia. During the infusion of GHB, normocapnia was maintained by manually assisting ventilation as necessary. The infusion of GHB did not affect Vmean [awake: 57 +/- 12 cm s-1 (mean +/- SD); 22.5 min: 62 +/- 15 cm s-1, NS difference] or mean arterial blood pressure (MAP) (awake: 97 +/- 12 mmHg; 22.5 min: 89 +/- 10 mmHg, NS). This suggests that cerebral blood flow velocity is unaltered by an anaesthetic dose of GHB. Twenty-five minutes after the start of GHB, fentanyl 3 micrograms kg-1 and vecuronium 0.1 mg kg-1 were given, the trachea was intubated and the lungs were mechanically ventilated to maintain end-tidal PCO2 of 4.6 +/- 0.4 kPa (30 min). At 30 min after the start of the GHB infusion, Vmean and MAP decreased to 38 +/- 10 cm s-1 and 76 +/- 12 mmHg (both P < 0.05 vs 22.5 min) respectively. After adjusting the ventilation to achieve hypocapnia (40 min: end-tidal PCO2 3.5 +/- 0.2 mmHg), Vmean decreased to 29 +/- 7 cm s-1, while MAP did not change. This allowed the relative vasoreactivity (percentage change in Vmean/0.133 kPa change in the end-tidal PCO2 from normocapnia to hypocapnia) to be estimated as 2.7 +/- 1.6% 0.133 kPa-1. This suggests that cerebrovascular response to CO2 during gamma-hydroxybutyrate/fentanyl anaesthesia is maintained.

Anesthesia for cesarean section and acid aspiration prophylaxis: a German survey.

UNLABELLED: We surveyed routine anesthetic practice and measures to prevent acid aspiration syndrome (AAS) in patients undergoing cesarean section (CS) throughout Germany. Of 1061 questionnaires, 81.9% were returned. For scheduled CS, general anesthesia was used in 63% of cases, and for urgent CS, it was used in 82% of cases. Regional anesthesia was used less often for both scheduled and urgent CS in smaller (< or =500 deliveries/yr; 28% and 16%, respectively) than in medium-sized (500-1000 deliveries/yr; 42% and 19%, respectively) or major obstetric departments (>1000 deliveries/yr; 45% and 21%, respectively). Among the regional techniques, epidural anesthesia (59%) was preferred more than spinal anesthesia (40%) in scheduled CS. In urgent CS, spinal anesthesia predominated (56% vs 42%). Pharmacological AAS prophylaxis is routinely used in 69% (68%) of departments before elective (urgent) CS under general anesthesia and in 52% under regional anesthesia. H2-blocking drugs are preferred for AAS prophylaxis over H2-blocker plus sodium citrate and sodium citrate alone. Both the incidence of and the mortality from AAS at CS are very low in Germany (<1 fatality per year). Nevertheless, AAS prophylaxis deserves more widespread use in obstetric anesthesia and in other patients at risk (e.g., children, outpatients). IMPLICATIONS: According to a countrywide survey, the use of regional anesthesia for cesarean section and pharmacological prophylaxis of acid aspiration syndrome is considerably less common in Germany than in the United States, United Kingdom, or other European countries.

Surveys on the use of regional anaesthesia in obstetrics.

Regional anaesthetic techniques in obstetrics have gained more and more importance during the last few years. Several surveys published recently show a remarkable increase in caesarean sections performed under regional anaesthesia, in many countries. Furthermore, epidural analgesia has proved to be one of the most effective methods of pain relief during vaginal delivery. Especially in patients at risk of an abdominal delivery, an epidural catheter already in place during labour can be used for consecutive caesarean section without delay and is used as a strong argument in favour of epidural anaesthesia. This article gives an overview of recent surveys of regional anaesthesia in obstetrics.

[Use of mechanical autotransfusion in maxillofacial surgery in the mouth, jaw and face]. / Zum Einsatz der maschinellen Autotransfusion bei Dysgnathie-operationen in der Mund-, Kiefer- und Gesichtschirurgie.

OBJECTIVE: In maxillofacial surgery considerable blood loss is not uncommon. However, the use of autologous blood collected from the site of surgery is controversial. METHODS: Bacterial contamination of blood collected for autologous retransfusion was studied by standard microbiological methods in 25 patients undergoing elective non-malignant maxillofacial surgery. Swabs were taken from the pharynx and from the collected blood before and after routine treatment. The autologous blood was not used for transfusion. Preoperative antibiotic treatment consisted in amoxicilline plus clavulanic acid. RESULTS: The blood prepared for retransfusion was free of bacteria in only one case, while 24 samples contained up to five different bacterial species including some strains not preexistent in the pharyngeal swabs. CONCLUSION: Blood collected from the site of operation is not suitable for retransfusion in maxillofacial surgery.

[Anesthesia in cesarean section in the FRG in 1997. Results of a nationwide survey]. / Anästhesie zum Kaiserschnitt in der BRD 1997. Eine Bestandsaufnahme anhand der Ergebnisse einer Bundesweiten Umfrage.

A survey of all German hospitals providing obstetric anaesthesia in 1997 (n = 1061, recovery rate 82% comprising 115,000 Caesarean sections revealed that most Caesarean sections (CS) are performed under general anaesthesia (GA). For elective CS, the average was 63%, and 82% for urgent (non-emergency) section. Succinylcholine is the standard neuromuscular blocker for intubation. Of the regional techniques, epidural continuous anaesthesia (ED) is preferred for elective CS (59%) over subarachnoid (SA, 10%) and combined epidural and subarachnoid anaesthesia (CSE). In urgent CS, SA is used more often (56%) than ED (42%) and CSE. With increasing number of births per year, the use of regional techniques is more common.

The NO synthase inhibitors L-Name and L-NMMA, but not L-arginine, block the mammalian nicotinic acetylcholine receptor channel.

(1) Nitric oxide (NO) synthase inhibitors (NOS-I) such as L-Name (N(G)-nitro L-arginine methyl ester) and L-NMMA (N(G)-monomethyl L-arginine) may enhance anesthesia indirectly by inhibiting the NO pathway. Moreover, NOS-I interact directly with receptor proteins. In an animal study, L-NMMA potentiated muscle relaxants. (2) The present experiments investigate the effects of L-NMMA, L-Name, and L-arginine on the nicotinic acetylcholine receptor channel (nAChR) using patch clamp techniques and a piezo-driven application system. Both NOS-I appear to directly interact with the nAChR in the open as well as in the closed conformation. L-Arginine has no effect.

Interaction of midazolam with the nicotinic acetylcholine receptor of mouse myotubes.

The effects of midazolam on the peripheral embryonic nicotinergic acetylcholine receptor (nAChR) of mouse myotubes were studied to elucidate the mechanism of its effect on neuromuscular transmission. Standard patch clamp techniques on outside-out patches were used. Pulses of 10(-4) M acetylcholine (ACh) applied by a liquid filament switch technique elicited macroscopic channel currents with a peak current amplitude of approximately 40 pA within <1 ms. The current decayed with a time constant of 30-100 ms due to desensitization. When midazolam was added in stepwise increased concentrations (10(-7) M to 7 x 10(-4) M) to the pulses, the current decay became bi-exponential, and a concentration-dependent decrease of the fast component of decay was observed. The current amplitude, however, was reduced slightly, and only at high concentrations of midazolam. This may indicate that midazolam binds to the open channel to cause the block. The rate constant of block (b(+1)) was found to be 1.8 x 10(6) M/s. Recovery experiments revealed a rate of unblocking (b(-1)) of approximately 2 x 10(-1) s(-1). After preincubation of the patches with midazolam, a substantial reduction of the current amplitude was seen at very low midazolam concentrations (<10(-7) M), which suggests an additional closed channel block with a Kd of approximately 10(-6) M. This closed channel block may be responsible for the muscle-relaxing effects of midazolam.

Isoflurane and sevoflurane interact with the nicotinic acetylcholine receptor channels in micromolar concentrations.

BACKGROUND: This study was performed to elucidate and compare the effects of sevoflurane and of isoflurane on the nicotinic acetylcholine receptor of mouse myotubes. The experiments were done with special reference to anesthetic concentrations considerably less than those used for clinical anesthesia. METHODS: The patch-clamp technique was used to record acetylcholine-activated currents from the embryonic type of the nicotinic acetylcholine receptor in the outside-out mode. A piezo-driven liquid filament switch was used for the ultrafast application of acetylcholine alone or in combination with isoflurane or sevoflurane. In addition, the patches were preexposed to either anesthetic, preceding the activation with acetylcholine. RESULTS: The current elicited by acetylcholine was reduced reversibly and in a concentration-dependent manner by both anesthetics, which were equally effective. Preexposure of the patches to isoflurane or sevoflurane showed an additional inhibition that was present at micromolar concentrations. The time courses of current decay could be fitted by single exponentials for isoflurane. At higher concentrations of sevoflurane, the current decay became biexponential. In contrast to isoflurane, sevoflurane increased the time constants of desensitization when applied in low concentrations. CONCLUSIONS: At the nicotinic acetylcholine receptor, isoflurane and sevoflurane act primarily through the same mechanisms: Both affect the open and the closed state of the channels in concentrations equal to and less than those encountered clinically. The kinetics of desensitization, however, are altered in a different manner. Thus there may be several different sites of interaction.

Ketamine blocks currents through mammalian nicotinic acetylcholine receptor channels by interaction with both the open and the closed state.

Single channel recordings have shown that ketamine (Ket) decreases the open time of the nicotinic acetylcholine receptor channel (nAChR). The present experiments on simultaneous openings of the nAChRs of mouse myotubes investigate the interaction of Ket with the open as well as with the closed state of the channels. The patch-clamp technique was used to record currents activated by 10(-4) M acetylcholine (ACh) in the outside-out mode. ACh together with increasing concentrations of Ket was applied with a piezo-driven system. In a second protocol, the patches were preexposed to Ket before activation with ACh. With addition of Ket, the currents showed a biexponential decay, indicating an open-channel block. The peak current amplitude decreased reversibly and in a concentration-dependent manner. The rate constants of block (b+1) and of unblock (b-1) were modeled by computer simulation and were found to be: b+1 = 3 x 10(6) M/s, b-1 = 100/s. Preexposure of the patches to Ket revealed an additional block with a KD of approximately 2 x 10(-6) M, which is below clinical concentrations. These data suggest that Ket also interacts with the closed state of the nAChR.