Cholinesterases in cardiac ganglia and modulation of canine intrinsic cardiac neuronal activity

Cholinergic neurotransmission plays a significant role in intrinsic cardiac ganglia with the action of acetylcholine being terminated by acetylcholinesterase (AChE, EC 3.1.1.7). Anatomical studies were performed to characterize neurons associated with AChE and a closely related enzyme, butyrylcholinesterase (BuChE, EC 3.1.1.8), in canine intrinsic cardiac ganglia. Histochemical staining for AChE and BuChE in canine right atrial neurons showed that there were four neuronal populations, namely, those that contained AChE only, BuChE only, both AChE and BuChE, and those that did not contain either enzymes. The neuronal activity of intrinsic cardiac neurons in response to substrates and inhibitors of cholinesterases were studied in anesthetized dogs. The activity of intrinsic cardiac neurons, as measured by changes in the number of action potentials, increased by local application of acetylcholine. However, local application of butyrylcholine led to a considerably greater increase in the activity of intrinsic cardiac neurons. In keeping with the neurochemical heterogeneity in intrinsic cardiac ganglia with respect to cholinesterases, the activity generated by most butyrylcholine-sensitive neurons was not influenced by acetylcholine and the activity generated by the most acetylcholine-sensitive neurons was not influenced by butyrylcholine. This suggests that these two agents preferentially influence different populations of intrinsic cardiac neurons. Enzyme kinetic studies demonstrated that canine AChE preferentially catalyzed the hydrolysis of acetylcholine while canine BuChE preferentially catalyzed the hydrolysis of butyrylcholine. Cholinesterase inhibitors Ro 2-1250 and Ro 2-0638 inhibited both canine cholinesterases, while huperzine A preferentially inhibited canine AChE and ethopropazine inhibited canine BuChE. The activity of neurons in the intrinsic cardiac ganglia significantly increased when Ro 2-1250 or Ro 2-0638 was administered locally. The activity of neurons was not affected when huperzine A or ethopropazine was administered, indicating that both cholinesterases must be inhibited to increase neuronal activity. In summary, these data show that in addition to AChE, intrinsic cardiac ganglia also contain distinct populations of neurons that are associated with BuChE, and the activity generated by these neurons is differentially influenced by their substrates. Because simultaneous inhibition of AChE and BuChE leads to increased neuronal activity, it is concluded that AChE- and BuChE-positive intrinsic cardiac neurons may act synergistically to influence the overall tonic activity of intrinsic cardiac ganglia.

[Guidelines for the evaluation of internal quality control of smears for screening of uterine cancer in France in the structures of Pathologic Anatomy and Cytology. French Association for Quality Assurance in Pathologic Anatomy and Cytology (AFAQAP)--Commission for cervical smears]

A national organized mass-screening effective programme is the only way to reduce the risk of cervical cancer, if properly organized and correlated with a system of Quality Assurance. Since 1900, an Association for Quality Assurance was created by the French pathologists, named "AFAQAP". These pathologists thus demonstrated their interest in this kind of action that should be effective if women and clinicians are also implied. The pathologists have concluded the first part of their programme with these French guidelines for internal quality control of pap smears.

Group B streptococcal bacteraemia in the elderly

The aim of this retrospective study was to determine the clinical spectrum of group B streptococcal (GBS) bacteraemia in patients over 70 years old. Sixty-six adults with GBS bacteraemia were reviewed over a 5-year period. Disease characteristics, clinical diagnoses and underlying disease were compared in 33 older patients (mean age 82.4 years) and 33 younger patients (mean age 54.2 years). The older patients were also compared with a control group (mean age 81.3 years). Urinary tract infection (39%), skin infection (33%) and pneumonia (24%) were the most frequent clinical diagnoses in older patients. Urinary tract infection (39% versus 6%) was significantly more frequent in older than in younger patients. One underlying disease and one condition were more frequent in elderly patients: congestive heart failure (39% versus 6%) and being bedridden (36% versus 0%). A comparison with the older control group showed that being bedridden was highly associated with GBS bacteraemia and was an important mortality factor amongst older patients (10% versus 30%). In conclusion, GBS disease in the elderly was found to be a severe clinical problem with a high mortality despite appropriate treatment.

Molecular cloning of genes differentially regulated by TNF-alpha in bovine aortic endothelial cells, fibroblasts and smooth muscle cells

OBJECTIVE

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic-cytokine binding to and thereby stimulating vascular cells. TNF-alpha mediated intermediate stimulation of vascular cells is believed to play a pivotal role in the development of arteriosclerosis. While extensive information has recently become available on gene induction by TNF-alpha, less is known about gene suppression by TNF-alpha in vascular cells. Endothelial cells are the first cell layer within the vessel wall interacting with circulating, cytokine releasing cells. Therefore, they were selected as target for these study.

METHODS

A differential screening approach has been used to isolate cDNAs whose abundance was suppressed by incubating bovine aortic endothelial cells (BAEC) for 6 h with 1 nM TNF-alpha. The gene expression of 6 isolated cDNAs after TNF-alpha was investigated by dot blots and nuclear run-on analysis in BAEC. The investigated genes were partially or completely sequenced. Differential expression after TNF-alpha stimulation of BAEC, bovine fibroblasts and vascular smooth muscle cells (SMC) was studied by Northern blots. RNA transcripts of the clone C7 in aortic aneurysms were examined by in situ hybridization.

RESULTS

49 independent cDNAs were isolated by the differential screening approach and 6 clones were further analyzed. These genes were downregulated in a time and dose dependent manner in BAEC. Sequence analysis revealed that 3 cDNAs encoded previously unidentified genes (C1, C5, C7), while 3 encoded known genes: connective tissue growth factor (CTGF; A1), fibronectin (A8) and the mitochondrial genome (B1). A1 and B1 were suppressed in BAEC, fibroblasts and SMC, whereas A8, C1, C5 and C7 were not uniformly downregulated in the investigated cells. C7 RNA transcripts were exclusively induced in the endothelium of an uninflamed aortic aneurysm. The transcripts were undetectable in an inflamed aortic aneurysm and control vessels.

CONCLUSIONS

Gene suppression is a prominent feature of the intermediate effect of TNF-alpha on endothelial cells. Differences in the expression of the tested genes in endothelial cells, fibroblasts and vascular smooth muscle cells open possibilities for the study of cellular interactions in the vascular wall in disease situations with high local TNF-alpha concentrations.

Increased ATP production during long-term brain ischemia in rats in the presence of propentofylline

Forty adult rats were subjected to stepwise two- and four-brain vessel occlusion and propentofylline 25 mg/day per kilogram body weight was intraperitoneally administered for 1 week or 3 weeks. Adenosine 5'-triphosphate, creatine phosphate, adenosine 5'-diphosphate and adenosine were determined in rat parietotemporal cortex by high-pressure liquid chromatography; lactate and pyruvate were measured spectrophotometrically. Stepwise and permanent long-term brain vessel occlusion gradually reduced the concentration of energy-rich phosphates and induced a marked increase in the concentration of adenosine, a parameter of ischemia. Three weeks of propentofylline treatment resulted in a significant increase in cerebral adenosine 5'-triphosphate concentration from 2.16 +/- 0.15 [(-)-propentofylline] to 2.70 +/- 0.24 nmol/mg wet weight during four-vessel occlusion (+25%). This was associated with an enhancement of the adenosine 5'-triphosphate/adenosine 5'-diphosphate ratio (+33%), mainly because of the significant reduction in adenosine 5'-diphosphate concentration. Propentofylline did not prevent the increase in lactate concentration during permanent brain vessel occlusion, but significantly reduced the tissue concentration of adenosine. In summary, the results demonstrate that continuous propentofylline administration over 3 weeks induced a striking increase in rat cortical adenosine 5'-triphosphate concentration during long-term brain vessel occlusion. Thus, propentofylline may have possible neuroprotective effects and could be used in the treatment of patients with chronic cerebrovascular disorders.

[Desflurane versus isoflurane in geriatric patients. A comparison of psychomotor and postoperative well-being following abdominal surgical procedures]

PURPOSE

The new volatile anaesthetic agent desflurane has a significantly lower blood-gas partition coefficient (0.42) than isoflurane (1.4), suggesting excellent intraoperative control of anaesthesia and rapid emergence and recovery from anaesthesia. However, only limited experience is available in geriatric patients undergoing major abdominal surgery.

METHODS

After approval by the local ethics committee and with written informed consent, 52 patients (> or = 65 years old, ASA class II or III) scheduled for major abdominal surgery were randomised to receive either desflurane (DES) or isoflurane (ISO) for maintenance of anaesthesia. After oral premedication with midazolam 3.75-7.5 mg, anaesthesia was induced with etomidate 0.2-0.3 mg/kg and fentanyl 3 micrograms/kg. Vecuronium 0.1 mg/kg provided muscle relaxation for endotracheal intubation. All patients were mechanically ventilated to maintain normocapnia. For maintenance of anaesthesia, DES or ISO was administered in 60% N2O and additional boluses of fentanyl and vecuronium were given as required. At the end of surgery, the neuromuscular blockade was reversed with neostigmine 0.02 mg/kg and DES or ISO was discontinued at the end of skin closure. Episodes of bradycardia and tachycardia and hypo- and hypertension, the time from the end of anaesthesia to extubation, opening eyes, squeezing hand, stating name and birthdate and to discharge from the recovery room were recorded. Until 360 minutes after the end of anaesthesia, the recovery of psychomotor functions was measured by means of simple reaction time tests, critical flicker fusion test, labyrinth test, ball bearing test, short and long-term memory test and digit symbol substitution test. The patient's well-being was documented with scores for pain, sedation and postoperative nausea and vomiting.

RESULTS

Demographic data in both groups was similar (Tab. 1). Anaesthesia was significantly prolonged in the ISO group. No significant differences between groups were found for MAC hours and the total dose of fentanyl and vecuronium administered (Tab. 3). Intraoperative haemodynamics were comparable between both groups (Tab. 4). No episodes of increases in heart rate or blood pressure associated with rapid increases in DES concentration were seen. Early emergence parameters were faster in the DES group (Tab. 5). When compared to ISO, the overall test performance and testing ability was superior following DES. Psychomotor tests showed significantly better results up to 240 minutes after the end of DES anaesthesia (Tab. 7, Fig. 4). Comparing the postoperative well-being, there were mild advantages for DES (Tab. 6, Fig. 1, 2, 3). However, time to discharge of geriatric patients from the recovery room was significantly shorter in the DES group (median 171 vs. 215 min., p < 0.05).

CONCLUSION

Using a balanced anaesthesia technique, we found desflurane as suitable as isoflurane for geriatric patients. Additionally, due to the fast emergence from anaesthesia, an improved cooperativity was found. In the DES group overall better postoperative psychomotor performance resulted in a shortening of discharge times from the recovery room. Hence, desflurane anaesthesia may be advantageous in geriatric patients.

Inhaled nitric oxide inhibits human platelet aggregation, P-selectin expression, and fibrinogen binding in vitro and in vivo

BACKGROUND

Recent data suggest that inhaled NO can inhibit platelet aggregation. This study investigates whether inhaled NO affects the expression level and avidity of platelet membrane receptors that mediate platelet adhesion and aggregation.

METHODS AND RESULTS

In 30 healthy volunteers, platelet-rich plasma was incubated with an air/5% CO2 mixture containing 0, 100, 450, and 884 ppm inhaled NO. ADP- and collagen-induced platelet aggregation, the membrane expression of P-selectin, and the binding of fibrinogen to the platelet glycoprotein (GP) IIb/IIIa receptor were determined before (t0) and during the 240 minutes of incubation. In addition, eight patients suffering from severe adult respiratory distress syndrome (ARDS) were investigated before and 120 minutes after the beginning of administration of 10 ppm inhaled NO. In vitro, NO led to a dose-dependent inhibition of both ADP-induced (3+/-3% at 884 ppm versus 70+/-6% at 0 ppm after 240 minutes; P<.001) and collagen-induced (13+/-5% versus 62+/-5%; P<.01) platelet aggregation. Furthermore, P-selectin expression (36+/-7% of t0 value; P<.01) and fibrinogen binding (33+/-11%; P<.01) were inhibited. In patients with ARDS, after two who did not respond to NO inhalation with an improvement in oxygenation had been excluded, an increase in plasma cGMP, prolongation of in vitro bleeding time, and inhibition of platelet aggregation and P-selectin expression were observed, and fibrinogen binding was also inhibited (19+/-7% versus 30+/-8%; P<.05).

CONCLUSIONS

NO-dependent inhibition of platelet aggregation may be caused by a decrease in fibrinogen binding to the platelet GP IIb/IIIa receptor.

Thrombomodulin modulates growth of tumor cells independent of its anticoagulant activity

Thrombomodulin (TM), recognized as an essential vessel wall cofactor of the antithrombotic mechanism, is also expressed by a wide range of tumor cells. Tumor cell lines subcloned from four patients with malignant melanoma displayed a negative correlation between TM expression and cell proliferation in vitro and in vivo. Overexpression of wild-type TM decreased cell proliferation in vitro and tumor growth in vivo. TM mutants with altered protein C activation capacity lead to a similar effect. In contrast, transfection of melanoma cells with mutant TM constructs, in which a portion of the cytoplasmic or lectin domain was deleted, abrogated the antiproliferative effect associated with overexpression of wild-type TM. Experiments performed with either peptide agonists/antagonists of the thrombin receptor, with hirudin, or with inhibitors of thrombin-TM interaction did not alter the growth inhibitory effect of TM overexpression. These data suggest that TM exerts an effect on cell proliferation independent of thrombin and the thrombin receptor, possibly related to the binding of novel ligands to determinants in the lectin domain which might trigger signal transduction pathways dependent on the cytoplasmic domain.

Bedside troponin T testing is not useful for early out-of-hospital diagnosis of myocardial infarction

BACKGROUND

A new commercially available rapid qualitative bedside immunoassay for cardiac troponin T has been developed. The aim of the study was to investigate whether this new rapid bedside cardiac troponin T assay facilitates diagnosing myocardial infarction in a pre-hospital setting.

METHODS

We evaluated the sensitivity and specificity of the new rapid bedside troponin T assay for myocardial infarction. In 68 patients with acute, central, crushing chest pain, who were strongly suspected of having myocardial infarction, the emergency doctor performed preclinically a bedside cardiac troponin T test. The results were compared with the diagnosis after admission to hospital, using the criteria of the World Health Organization.

RESULTS

The diagnosis of myocardial infarction was confirmed in 16/68 (24%) patients after admission to hospital, but only in 4/16 (25%) patients with myocardial infarction was a positive result observed preclinically with this test. The result was false positive in 1/5 patients (20%).

CONCLUSIONS

In contrast to an excellent specificity (0.98), sensitivity (0.25) of the rapid troponin T assay was poor. Thus, we conclude that this test cannot improve the distinction between myocardial infarction and angina pectoris in a pre-hospital setting.

[Stereoisomers in anesthesia. Theoretical basis and clinical significance]

All optically active molecules have at least one asymmetric atom in common which is attached to four ligands, that can have different three dimensional positions. Therefore it can be concluded that the resulting isomers are chemically identical in all respects except for the direction with which they rotate plane-polarized light. When the isomer and its corresponding enantiomer are present in equal proportions, they are called racemic mixture, a mixture that does not rotate polarized light, since the optical activities of the two isomers cancel each other. Although the isomers are chemically identical other optically active molecules can interact with these isomers in a geometrically specific way termed stereoselectivity. The human body comprises a chiral environment due to optically active proteins; thus it is not surprising that enantiomeric drugs exhibit different pharmacological properties, when used as pure optical isomers. Till today most modern anaesthetics have been optical isomers, which are mainly used as racemic mixture (1:1 mixture). For financial reasons pure isomers were only used for research purposes, but nowadays the wide clinical use of pure isomers is financially feasible due to new production techniques. The terms eutomer and distomer were chosen to indicate the more or less potent form of the drug. The clinical use of pure isomers is only of advisable, if there are significant differences between eutomer and distomer in desired or side effects. Among the modern anaesthetics ketamine, isoflurane, bupivacaine and atracurium exhibit an asymmetric carbon. For most drugs the separation in pure isomers will reduce side effects. For volatile anaesthetics this question is still unanswered, since experimental and clinical results are inconsistent so far.

Effects of preinduction and intraoperative warming during major laparotomy

We have investigated the influence of active warming before and during operation on blood loss, transfusion requirements, duration of stay in the post-anaesthesia care unit (PACU) and perioperative costs in 40 patients undergoing major abdominal surgery. Patients were allocated randomly to one of two groups: in the study group (n = 20), patients were actively warmed using forced air for 30 min before induction of general anaesthesia and during anaesthesia. Passive protection against heat loss consisted of circulating water mattresses, blankets and fluid warming devices, and was used both in the active warming group and in the control group (n = 20). At the end of surgery the change in core temperature was significantly less in the group of actively warmed patients (0.5 (SD 0.8) degree C vs 1.5 (0.8) degree C; P < or = 0.01). Blood loss and transfusion requirements were less in the actively warmed patients, who had a shorter duration of stay in the PACU (94 (SD 42) min vs 217 (169) min; P < or = 0.01) and a 24% reduction in total anaesthetic costs.

Relationship between hepatic cytochrome P450 3A content and activity and the disposition of midazolam administered orally

It was recently shown by others that the clearance of midazolam/kg body weight after iv administration correlates with hepatic cytochrome P450 (CYP or P450) 3A content in liver transplant patients. However, after po administration midazolam undergoes significant first-pass metabolism, with significant intestinal extraction. The relationship between hepatic CYP3A and midazolam disposition after po administration had not previously been investigated. The aim of this study was to compare intraindividually hepatic CYP3A content and activity with the in vivo pharmacokinetics of midazolam (7.5 mg) administered po. For 15 patients scheduled for partial liver resection, the AUC values for the observed time period (AUC0-5hr) and to infinity (AUCinf) and the clearance were determined. In a macroscopically normal area of resected liver tissue, the microsomal CYP3A4 content (nanomoles per nanomole of total P450) was measured by immunoblot analysis and parameters (apparent Vmax, apparent KM, and intrinsic clearance) for the microsomal alpha-hydroxylation of midazolam were determined. Clearance/kg in vivo correlated with the apparent Vmax (r2 = 0.45, p < 0.01) and the CYP3A4 content (r2 = 0.29, p < 0.05). We conclude that interindividual variability in the pharmacokinetics of po administered midazolam is in part determined by interindividual variability in the hepatic microsomal Vmax for the alpha-hydroxylation of midazolam. However, the relationship between the disposition of midazolam administered po and hepatic CYP3A content is weaker than that reported after iv administration, indicating the importance of the contribution of intestinal CYP3A to the in vivo disposition of midazolam administered po.

Intraoperative high dose rate brachytherapy in recurrent or metastatic colorectal carcinoma

BACKGROUND

The survival of patients with recurrent or metastatic colorectal cancer usually is less than 12 months. In an attempt to improve this dismal prognosis, we investigated the role of intraoperative high dose rate brachytherapy (IOHDR) in the management of these patients.

METHODS

From April 1992 to December 1996, 26 patients with locally recurrent or metastatic colorectal carcinoma were treated with maximal surgical resection and IOHDR. Intraoperative radiation dose ranged from 10 to 20 Gy, prescribed at 0.5 cm depth. The residual tumor irradiated was microscopic in 16 patients (62%) and gross residual in 10 patients (38%). Six patients received postoperative external beam radiation therapy.

RESULTS

After a median follow-up of 28 months (range 6 to 54 months), seven of 15 evaluable patients (47%) failed in the area treated with IOHDR. The median time to local failure was 21 months (range 4 to 52 months). The median survival was 23 months (microscopic 24 months; gross 17 months), with a 4-year actuarial survival rate of 36%. Major morbidity was observed in 7 patients (47%) and usually was surgery-related.

CONCLUSION

The use of IOHDR in association with radical resection increases local control in patients with recurrent or metastatic colorectal cancer. Patients with microscopic residual disease achieved a better result than do those with gross residual disease. Future strategies include the addition of limited EBRT dose to IOHDR, even for previously irradiated patients.

Comparison of ATB staph, rapid ATB staph, Vitek, and E-test methods for detection of oxacillin heteroresistance in staphylococci possessing mecA

The performance characteristics of the E-test (AB Biodisk, Solna, Sweden), the ATB Staph, the Rapid ATB Staph, and the Vitek GPS-503 card (bioMérieux, La Balme Les Grottes, France) methods for the detection of oxacillin resistance in a collection of staphylococci with a high proportion of troublesome strains were evaluated. Sixty-four Staphylococcus aureus strains and 76 coagulase-negative staphylococcal strains were tested. All strains were mecA positive and were characterized by the oxacillin agar screen plate test; 75 (53.6%) were found to be heterogeneous by a large-inoculum oxacillin disk diffusion assay, and oxacillin MICs for 89 (63.6%) were < or = 32 microg/ml. Three (4.7%) S. aureus strains and 25 (32.9%) coagulase-negative strains were classified as susceptible by the E-test, as defined by the National Committee for Clinical Laboratory Standards (NCCLS) oxacillin breakpoint (MIC < or = 2 microg/ml). The ATB Staph method failed to detect oxacillin resistance in 7 (11%) S. aureus isolates and 32 (42.1%) coagulase-negative isolates. The MICs for all but six of these discrepant isolates were < or = 16 microg/ml. The Rapid ATB Staph method was tested against S. aureus strains only and yielded 15 (23.4%) false-susceptible results for strains for which the MICs were < or = 32 microg/ml. The Vitek system was the best-performing system, since it failed to detect oxacillin resistance in only 3 (4.7%) S. aureus strains and 15 (19.7%) coagulase-negative strains, the MICs for all of which were < or = 2 microg/ml. These data indicate that (i) the performance of the two ATB Staph systems can be limited when the prevalence of borderline-heteroresistant staphylococci is high and (ii) the unreliability of the E-test and the Vitek methods for detecting resistant coagulase-negative strains might be reduced by the potential revision of the oxacillin breakpoint currently recommended by the NCCLS.

Anti-idiotype monoclonal antibodies specific for the MOPC167 anti-phosphocholine transgene-encoded antibody

Four rat x mouse hybridomas secreting monoclonal anti-idiotypic (anti-Id) antibodies (MAb) specific for the transgene-encoded antibody of the 207-4 transgenic mouse line, which carries the VH1/V kappa 24 gene segments of the IgA, phosphocholine-(PC) specific MOPC167 myeloma, were developed from a fusion of Ag8-X63.653 mouse cells with spleen cells from a rat immunized with MOPC167 and HPCM27 anti-PC antibodies. The anti-Id MAb were shown by ELISA to be specific for PC-binding proteins of VH1/V kappa 24 H and L chains of various isotypes. They did not bind VH1/V kappa 22, VH1/V kappa 8, or VH1/V kappa 1 PC-binding proteins or other IgA or IgM myeloma proteins. Analysis by flow cytometry demonstrated that these MAb bind to the transgene-encoded membrane immunoglobulin (sIgM) as expressed on > 95% of the B220 positive 207-4 spleen cells. All four MAb were able to inhibit the binding of MOPC167 to PC conjugated to bovine serum albumin. Differences in fine specificity of binding were demonstrated by differential staining of spleen cells of the 216-7 mu kappa delta Mem MOPC167 transgenic mice. In these mice endogenous H chains associate with the transgene encoded L chain to form MOPC167 crossreactive idiotopes. Two of the MAb, 28-4-3 and 28-6-20, stained significant numbers of cells, while MAb 28-5-15 did not bind to 216-7 cells. Three of the MAb, 28-5-15, 28-6-20, and 28-4-3, when conjugated to Sepharose beads, were able to induce DNA synthesis in cultures of 207-4 transgenic spleen cells. None of the MAb were able to induce an antibody response in vivo. These MAb should prove useful in staining PC-transgenic B cells for flow cytometry studies and in defining early cellular events in the activation of idiotype positive B cells by anti-Id antibodies.