Diversity among clinical isolates of penicillin-resistant Streptococcus mitis: indication for a PBP1-dependent way to reach high levels of penicillin resistance

A total of 12 non-epidemiologically related clinical isolates of Streptococcus mitis that showed different levels of resistance to penicillin were studied. Membrane-protein profiles and penicillin-binding protein (PBP) patterns showed a great polymorphism; and patterns of 4-7 PBPs, with sizes that ranged from approximately 101 kDa to approximately 40 kDa, were detected in each strain. No association could be found between PBP pattern and resistance level to penicillin among these isolates. Arbitrarily primed PCR confirmed the genetic diversity among this group of streptococci. One of the isolates of intermediate level of resistance to penicillin, which showed a PBP pattern similar to that of the high-resistance strains, was used as a laboratory model to analyse the mechanism underlying high-resistance acquisition by these strains. A 14-fold increase in penicillin resistance was obtained after a single selection step, which resulted in a decrease in penicillin affinity for PBP1. The size of this PBP (92 kDa) and the differences in PBP profiles of the penicillin-resistant clinical isolates suggest the existence in S. mitis of PBP-mediated mechanisms to acquire high-level resistance to penicillin, among which alterations in PBP1 seem to play a main role, in contrast to the PBP2X mediated mechanism described for other streptococci.

Exploiting conformationally constrained peptidomimetics and an efficient human-compatible delivery system in synthetic vaccine design

Peptide and protein mimetics are potentially of great value in synthetic vaccine design. The mimetics should function by stimulating the immune system to produce antibodies that recognize the intact parasite. Also the mimetics should be presented to the immune system in a way that leads to efficient antibody production. Here we investigate the application of cyclic peptidomimetics presented on immunopotentiating reconstituted influenza virosomes (IRIVs), a form of antigen delivery that is licensed already for human clinical use, in synthetic vaccine design. We focus on the central (NPNA)(n) repeat region of the circumsporozoite (CS) protein of the malaria parasite Plasmodium falciparum as a model system. Cyclic peptidomimetics of the NPNA repeats were incorporated into both an IRIV and (for comparison) a multiple-antigen peptide (MAP). Both IRIV and MAP delivery forms induced mimetic-specific humoral immune responses in mice, but only with the mimetic-IRIV preparations did a significant fraction of the elicited antibodies cross-react with sporozoites. The results demonstrate that IRIVs are a delivery system suitable for the efficient induction of antibody responses against conformational epitopes by use of cyclic template-bound peptidomimetics. Combined with combinatorial chemistry, this approach may have great potential for the rapid optimization of molecularly defined synthetic vaccine candidates against a wide variety of infectious agents.

Export of Thermus thermophilus alkaline phosphatase via the twin-arginine translocation pathway in Escherichia coli

The bacterial twin-arginine translocation (Tat) pathway is distinct from the Sec system by its remarkable capacity to export folded enzymes. To address the question whether the two systems are capable of translocating homologous enzymes catalyzing the same reaction, we cloned the tap gene encoding Thermus thermophilus alkaline phosphatase (Tap) and expressed it in Escherichia coli. Unlike the alkaline phosphatase of E. coli, which is translocated through the Sec system and then activated in the periplasm, Tap was exported exclusively via the Tat pathway and active Tap precursor was observed in the cytoplasm. These results demonstrate that two sequence and functional related enzymes are exported by distinct protein transport systems, which may play an integral role in the bacterial adaptation to their environment during the evolution.

Mortality after discharge from intensive care: the impact of organ system failure and nursing workload use at discharge

OBJECTIVES

Mortality after ICU discharge accounts for approx. 20-30% of deaths. We examined whether post-ICU discharge mortality is associated with the presence and severity of organ dysfunction/failure just before ICU discharge.

PATIENTS AND METHODS

The study used the database of the EURICUS-II study, with a total of 4,621 patients, including 2,958 discharged alive to the general wards (post-ICU mortality 8.6%). Over a 4-month period we collected clinical and demographic characteristics, including the Simplified Acute Physiology Score (SAPS II), Nine Equivalents of Nursing Manpower Use Score, and Sequential Organ Failure Assessment (SOFA) score.

RESULTS

Those who died in the hospital after ICU discharge had a higher SAPS II score, were more frequently nonoperative, admitted from the ward, and had stayed longer in the ICU. Their degree of organ dysfunction/failure was higher (admission, maximum, and delta SOFA scores). They required more nursing workload resources while in the ICU. Both the amount of organ dysfunction/failure (especially cardiovascular, neurological, renal, and respiratory) and the amount of nursing workload that they required on the day before discharge were higher. The presence of residual CNS and renal dysfunction/failure were especially prognostic factors at ICU discharge. Multivariate analysis showed only predischarge organ dysfunction/failure to be important; thus the increased use of nursing workload resources before discharge probably reflects only the underlying organ dysfunction/failure.

CONCLUSIONS

It is better to delay the discharge of a patient with organ dysfunction/failure from the ICU, unless adequate monitoring and therapeutic resources are available in the ward.

[Treatment of acute myocardial infarction with the x-sizer coronary thrombectomy device]

The abundant thrombi present in infarct-related arteries may impair the angiographic result of primary angioplasty in acute myocardial infarction. We describe the utilization of the thrombus-removal device X-Sizer before coronary stenting in 4 patients with acute myocardial infarction treated with primary angioplasty. The procedure was successful in all the cases and the patients were discharged without complications.

Bleomycin-induced chronic lung damage does not resemble human idiopathic pulmonary fibrosis

Administration of bleomycin into the lungs of experimental animals has been utilized as a model to understand human pulmonary fibrosis. Most of the studies, however, have focused on early stages of the lung reaction. We hypothesized that chronic stages of the model may not mimic idiopathic pulmonary fibrosis, since in preliminary studies, lung volume and compliance were not decreased. Eight male Sprague-Dawley rats receiving intratracheal bleomycin (0.5 U/100 g body weight) underwent measurement of FRC, inspiratory capacity, and lung compliance 120 d later. Lung histologic changes were evaluated using light microscopy. Eight rats without intervention served as controls. Results show that our model, in early stages, has histologic changes no different from those previously described elsewhere. In chronic stages, however, the model does not behave as a restrictive syndrome: FRC is normal or increased, whereas lung compliance is normal. Focal peribronchiolar inflammation and fibrosis associated with paracicatricial emphysematous changes are the main histologic features of long-term lung remodeling after bleomycin. We conclude that while the chronic stages of the model may be informative in understanding mechanisms of fibrosis, care should be taken not to extrapolate to human idiopathic pulmonary fibrosis. We speculate that the model might resemble a particular subgroup of human interstitial lung disease, namely, those involving peribronchiolar structures.

Outgassing behavior and composition of comet C/1999 S4 (LINEAR) during its disruption

The gas activity of comet C/1999 S4 (LINEAR) was monitored at radio wavelengths during its disruption. A runaway fragmentation of the nucleus may have begun around 18 July 2000 and proceeded until 23 July. The mass in small icy debris (</=30-centimeter radius) was comparable to the mass in the large fragments seen in optical images. The mass budget after breakup suggests a small nucleus ( approximately 100- to 300-meter radius) that had been losing debris for weeks. The HNC, H2CO, H2S, and CS abundances relative to H2O measured during breakup are consistent with those obtained in other comets. However, a deficiency in CH3OH and CO is observed.

[Regional diastolic function is more preserved in viable than non-viable myocardium. Demonstration by pulsed-wave Doppler tissue imaging in basal conditions]

INTRODUCTION AND OBJECTIVES

The aim of this study was to analyze the differences in regional diastolic function between viable and non-viable myocardium when assessed by pulsed-wave Doppler tissue imaging performed in basal conditions.

PATIENTS AND METHODS

The study population included 21 patients with three-vessel disease and regional systolic dysfunction. These patients underwent transthoracic echocardiographic study and pulsed-wave Doppler tissue imaging in basal conditions and, in addition, stress echocardiography with dobutamine performed by a different investigator.

RESULTS

Three-hundred and twenty-two segments were studied, 140 of which (43%) had systolic dysfunction. Of the 140 segments with systolic dysfunction, 52 (37%) were considered hypokinetic by transthoracic echocardiography, 80 (57%) akinetic and 8 (6%) dyskinetic. As assessed by dobutamine echocardiography, 67 segments (48%) were considered viable and 73 (52%) non-viable. Viable segments had a higher peak velocity of the early diastolic wave e (5.5 +/- 1.9 vs. 4.7 +/- 2.0 cm/s; p = 0.03). An e/a ratio < 1 was more frequent in non-viable versus non-viable segments (52 vs. 70%; p < 0.05). There were no differences in relation to regional isovolumetric relaxation time and peak velocity of a wave. Although peak velocity of s wave was lower in non-viable segments, differences were not statistically significant.

CONCLUSION

Compared with non-viable segments, viable myocardial segments have less impaired regional diastolic function as assessed by pulsed-wave Doppler tissue imaging.

A putative, ubiquitin-dependent mechanism for the recognition and elimination of defective spermatozoa in the mammalian epididymis

The normal structure and function of sperm are prerequisites for successful fertilization and embryonic development, but little is known about how defective sperm are eliminated during mammalian spermatogenesis. Here, we describe a ubiquitin-dependent, sperm quality control mechanism that resides in the mammalian epididymis, the site of sperm maturation and storage. We used immunofluorescence, electron microscopy, western blotting and pulse-chase experiments to show that ubiquitin is secreted by the epididymal epithelium and binds to the surface of defective sperm. Most of the ubiquitinated sperm are subsequently phagocytosed by the epididymal epithelial cells. A portion of defective sperm escapes phagocytosis and can be found in the ejaculate. Cultured epididymal cells maintain their ability to produce ubiquitin and phagocytose the defective sperm, as well as the ubiquitin-coated microspheres, in vitro. The surprising phenomenon of cell-surface ubiquitination in defective sperm provides a possible mechanism for sperm quality control in mammals and a new marker of semen abnormalities in men and animals.

[In-hospital major complications associated with rotational atherectomy: experience with 800 patients at a single center]

INTRODUCTION

Rotational atherectomy is usually performed in patients with angiographically determined high risk coronary lesions. The aim of this study was to evaluate the rate of major adverse cardiac events (death, Q-wave infarction or new revascularization) after rotational atherectomy, as well as to identify the clinical characteristics associated with this incidence.

PATIENTS AND METHODS

The study population included 800 patients treated with rotational atherectomy from 1993 to 1999: 512 (64%), for de novo lesions, and 288 (36%) for restenosis. Balloon dilation and coronary stenting was performed in 95% and 34% of patients, respectively.

RESULTS

During hospitalization, 17 patients (2.1%) died, 16 (2%) had a Q-wave infarction, 30 (3.8%) a non-Q infarction, and new revascularization was performed in 28 (3.5%). The incidence of major adverse cardiac events was 6.5% (n = 52), this incidence being higher in the presence of diabetes (8.9 vs. 4.4%; p = 0.01), unstable angina or acute/recent myocardial infarction (7.6 vs. 3.3%; p = 0.02), multivessel disease (8.6 vs. 3.3%; p < 0.01), treated vessel other than right coronary (7.0 vs. 1.7%; p = 0.01), procedure in > 1 vessel (10.7 vs. 4.7%; p < 0.01), angiographic failure (62.5 vs. 5.5%; p < 0.001), and de novo lesions (8.4 vs. 2.5%; p < 0.01), with diabetes and treatment of de novo lesions being independent predictors of major adverse cardiac events. However, age, previous infarction, and left ventricular dysfunction, were not associated with the rate of events.

CONCLUSION

Some simple variables are associated with a higher incidence of major adverse cardiac events after rotational atherectomy. Advanced age, previous infarction and left ventricular dysfunction, however, do not necessarily imply a poorer prognosis in these patients.

Rhoptry-associated protein 1-binding monoclonal antibody raised against a heterologous peptide sequence inhibits Plasmodium falciparum growth in vitro

Monoclonal antibodies (MAbs) specific for Plasmodium falciparum rhoptry-associated protein 1 (RAP-1) were generated and tested for inhibition of parasite growth in vitro. The majority of indirect immunofluorescence assay (IFA)-positive MAbs raised against recombinant RAP-1 positions 23 to 711 (rRAP-1(23-711)) recognized epitopes located in the immunodominant N-terminal third of RAP-1. MAbs specific for the building block 35.1 of the synthetic peptide malaria vaccine SPf66 also yielded an IFA staining pattern characteristic for rhoptry-associated proteins and reacted specifically with rRAP-1 and parasite-derived RAP-1 molecules p67 and p82. Cross-reactivity with RAP-1 was blocked by the 35.1 peptide. Epitope mapping with truncated rRAP-1 molecules and overlapping peptides identified the linear RAP-1 sequence Y218KYSL222 as a target of the anti-35.1 MAbs. This sequence lacks primary sequence similarity with the 35.1 peptide (YGGPANKKNAG). Cross-reactivity of the anti-35.1 MAbs thus appears to be associated with conformational rather than sequence homology. While the anti-35.1 MAb SP8.18 exhibited parasite growth-inhibitory activity, none of the tested anti-rRAP-1(23-711) MAbs inhibited parasite growth, independently of their fine specificity for the RAP-1 sequences at positions 33 to 42, 213 to 222, 243 to 247, 280 to 287, or 405 to 446. The growth-inhibitory activity of MAb SP8.18 was, however, accelerated by noninhibitory anti-RAP-1 MAbs. Results demonstrate that in addition to fine specificity, other binding parameters are also crucial for the inhibitory potential of an antibody.

[Utility of SPECT with 99m Tc-tetrofosmin and stimulus with dipyridamole in patients with permanent ventricular pacemakers]

BACKGROUND AND OBJECTIVE

Patients with permanent ventricular pacemakers (PP) are a difficult subgroup to assess in the study of coronary artery disease. The objective of this study was to evaluate the diagnostic value of the myocardial perfusion scintigraphy with 99mTC-Tetrofosmin (Tc-Tf) and stimulus with dipyridamole in patients with PP and suspected coronary artery disease.

PATIENTS AND METHODS

Fourteen patients with suspected coronary artery disease and without structural cardiopathy, who underwent Tc-Tf and cardiac catheterization, were studied retrospectively. Sensitivity, specificity, predictive values and Kappa index were calculated for the diagnosis of coronary artery disease, multivessel disease, and for each one of the coronary arteries (left anterior descending, right coronary, and circumflex). In addition, the correlation between the number of territories with perfusion defects and the number of diseased vessels was studied.

RESULTS

In regards to the diagnosis of coronary artery disease, sensitivity, specificity, positive predictive value, negative predictive value and the Kappa index were 100%, 50%, 83%, 100% and 0.55, respectively. For multi-vessel disease, these values were 83%, 64%, 64%, 83% and 0.43 respectively. The correlation coefficient between the number of territories with perfusion defects and the number of diseased vessels was 0.61 (p = 0.02). In the diagnosis of anterior descending disease, sensitivity and specificity were 83% and 88% respectively. For the right coronary artery, these values were 100% and 44% and for the circumflex artery 38% and 83%, respectively.

CONCLUSION

In patients with PP and suspected coronary artery disease, myocardial perfusion scintigraphy with Tc-Tf and stimulus with dipyridamole is of great value in the diagnosis of coronary artery disease and in the assessment of its extension.

Long-term outcome of patients with proximal left anterior descending coronary artery in-stent restenosis treated with rotational atherectomy

Once a first interventional procedure has failed, patients with proximal left anterior descending in-stent restenosis are frequently sent for surgical revascularization. Data on long-term outcome in selected patients with proximal left anterior descending in-stent restenosis treated with RA are lacking. The study's objective was to evaluate the long-term outcome of patients with proximal left anterior descending artery in-stent restenosis treated with rotational atherectomy. The study population is constituted by 42 patients with proximal left anterior descending in-stent restenosis treated with rotational atherectomy. Patients were followed up for 2.1 +/- 0.9 years (range, 6--54). Restenosis length was 16.5 +/- 9.2 mm, and restenosis was diffuse (> 10 mm in length) in 30 (71.4%). The rotational atherectomy procedure was guided by intravascular ultrasound in 18 patients (42.9%). Maximum burr/artery ratio was > 0.7 in 24 (57.1%) patients. One patient suffered a periprocedural non--Q-wave infarction, but no deaths, Q-wave infarction, or new target vessel revascularization occurred during hospitalization. There were no deaths or myocardial infarctions after discharge. Sixteen patients (38.1%) needed a new revascularization, but only five (11.9%) underwent coronary bypass grafting at the end of the follow-up (2.1 +/- 0.9 years). The rate of surgical revascularization at 6 months, 1 year, and 3 years was 4.8%, 7.4%, and 18.4%, respectively. The rate of new target vessel revascularization at 6 months, 1 year, and 3 years was 16.7%, 36.5%, and 40.5%, respectively. Patients with < or = 5 months since stent implantation had a significantly higher rate of new target vessel revascularization. Patients with proximal left anterior descending in-stent restenosis may be safely treated with rotational atherectomy. This strategy is associated with a very good long-term outcome, with few patients undergoing surgical revascularization.

Early coronary angioplasty for acute myocardial infarction: predictors of poor outcome in a non-selected population

AIMS

The objective of this study was to report the experience in the treatment of acute myocardial infarction (AMI) with early coronary angioplasty (PTCA) in a single European center during one decade, attempting to identify the characteristics associated with a poor prognosis in these patients.

METHODS AND RESULTS

Eight hundred patients with AMI were treated with PTCA < 12 hours after symptom onset. Mean age was 64 +/- 13 years, 12% were in cardiogenic shock, AMI location was anterior in 61% and PTCA was performed after failed thrombolysis in 5%. Coronary stents and abciximab were used in 51% and 10%, respectively. An angiographic successful result was obtained in 93%, and final TIMI flow grade 3 was achieved in 83%. The overall in-hospital mortality rate was 12.5% (2.7%, 16.1%, 25.7% and 63.8% in patients in Killip class I, II, III and IV, respectively). Over the years, an improvement in the angiographic results and a reduction in the rates of reinfarction and target vessel revascularization were observed. The independent predictors of death were age > 70 years, absence of hyper-cholesterolemia, anterior location, cardiogenic shock, multi-vessel disease and unsuccessful PTCA. The leading causes of mortality were cardiogenic shock (63%) and ventricular free wall rupture (14%). The rates of non-fatal reinfarction, documented reocclusion and in-hospital repeated revascularization were 2%, 3% and 4%, respectively.

CONCLUSION

In most cases, PTCA performed in a non-selected patient population with AMI results in angiographic success. Mortality especially occurs in patients who are in cardiogenic shock at the beginning of the procedure. We have observed an improvement in the results throughout the course of the decade.

[Meaning of clinical and electrical positivity in the myocardial perfusion scintigraphy during the administration of dipyridamole]

BACKGROUND AND OBJECTIVES

Administration of dipyridamole produces angina and ST depression in 20%-30% and 6%-34% of patients, respectively. This study aimed to evaluate the clinical implications of the presentation of angina and/or ST depression during the administration of dipyridamole in the study of coronary heart disease by myocardial perfusion SPECT (MPS).

METHODS

The study population is constituted by 593 consecutive patients without left branch block or ventricular pacemaker rhythm who were referred to our service to undergo MPS with dipyridamole. A SPECT was performed after the administration of 99mTc-tetrosfosmine and drug stimulation with dipyridamole (0.142 mg/kg/min for 4 minutes). A coronariography was performed in 338 patients (57%). The frequency of clinical and electrical positivity and their relationship with the MPS and the coronariography were studied.

RESULTS

The rate of angina and ST depression was 32% (n = 190) and 10% (n = 58), respectively. Myocardial perfusion defects were observed in 465 patients (78%), and signs of scintigraphic ischemia in 311 (52%). The patients with ST depression presented a higher frequency of perfusion defects (93% vs 76%, p = 0.0012) and scintigraphic ischemia (89% vs 49%, p < 0.0001). In addition, perfusion defects in more than one territory were observed in these patients in a higher percentage (53% vs 34%, p = 0.0036). Among the patients who underwent cardiac catheterization, those who had a ST depression had a greater extension of coronary heart disease (1.8 +/- 1.2 vs 1.3 +/- 1.0 diseased vessels, respectively. p = 0.0100) and a higher frequency of multivessel disease (61% vs 43%, p = 0.0380). Those patients who had clinical positivity showed a scintigraphic ischemia more frequently (66% vs 47%, p < 0.0001), however no statistically significant differences were observed between the presence of patients with perfusion defects or in the extension of these defects as well as in the number of diseased vessels in the coronariographic study.

CONCLUSIONS

During the administration of dipyridamole, the ST depression is associated with more frequent scintigraphic ischemia, larger extension of perfusion defects and more diseased vessels. The appearance of angina is associated with scintigraphic ischemia, but it is not necessarily associated with the extension of perfusion defects or greater number of diseased vessels.

Time course of serum hepatitis C virus-RNA during chronic hepatitis C treatment accurately predicts the type of response

AIM

To establish the value of alanine aminotransferase normalization and hepatitis C virus-RNA clearance as predictors of sustained virological response in naïve and relapser chronic hepatitis C patients on mono or combination therapy.

METHODS

A total of 282 hepatitis C patients were studied: 98 naïves on interferon, and 64 naïves and 75 relapsers on interferon plus oral ribavirin; 45 patients were excluded. Drugs were administered at standard doses for 12 months. Alanine aminotransferase and hepatitis C virus-RNA were determined at baseline and at weeks 4, 12, 24, 48, and at 72 and 96 weeks after completion of therapy.

RESULTS

The rate of sustained response was greater (P < 0.05) in naïves and relapsers on combination therapy (33% and 48%, respectively) than in naïves on interferon alone (16%). Hepatitis C virus-RNA significantly decreased from baseline by week 4 in naïves on interferon and relapsers on combination therapy and by week 12 in naïves on combination therapy. Alanine aminotransferase levels paralleled viremic load in naïves on interferon, yet in patients on combination therapy, alanine aminotransferase normalized independently of the virological response. During treatment, the main factor associated with sustained response was hepatitis C virus-RNA clearance by week 4 in naïves on interferon and relapsers on combination therapy, and by week 24 in naïves on combination therapy.

CONCLUSION

Clearance of viraemia constitutes the best predictor of a sustained response to therapy, but needs to be measured at patient-specific times.

Detection of squalene in alpha-fetoprotein and fetal serum albumin from bovine

Alpha-fetoprotein and fetal serum albumin have been simultaneously purified from fetal bovine serum by mild procedures utilizing ammonium sulfate, hydrophobic interaction, immobilized metal (nickel) affinity chromatography, and isoelectric focusing. The lipidic extract from each protein was analyzed by gas chromatography and the peak appearing just after the arachidonic acid was identified as squalene by gas chromatography-mass spectrometry. This isoprenoid was not detected formerly in these proteins from human, rat, bovine, and pig. Until recently, in the analysis of the fatty acid composition of the alpha-fetoprotein and serum albumin from mammals, a peak has been assigned in the last part of the chromatographic profile, after arachidonic acid, to docosahexaenoic acid. In the present work, it was found that the peak corresponds to squalene instead of docosahexaenoic acid. Furthermore, we conclude that bovine alpha-fetoprotein and fetal serum albumin carry squalene, but not docosahexaenoic acid. These results agree with others obtained analyzing the same proteins from chick embryo.

Successful stent delivery through 5 French guiding catheter

BACKGROUND AND OBJECTIVE

In vessels with moderate-severe tortuosity, rigidity or calcium, 6 French guiding catheters may be of help in stent delivering, allowing a deep coronary intubation and, hence, an easier coronary stent advancement. In this study, we describe our experience in coronary stenting using 5 French guiding catheters.

METHODS AND RESULTS

The study population is constituted by 46 patients in whom coronary stenting was attempted through a 5 French guiding catheter. Sixty-six stents were delivered in 56 vessels; the 5 French Zuma guiding catheter (MedtronicAVE, Minneapolis, Minnesota) was used. In 74% of cases, a moderate-severe tortuosity was present, and calcium was visible by fluoroscopy in 27%. The stented lesions were de novo in 95%, and 42% of stents were placed in the right coronary artery. The stent was successfully delivered and implanted in all but one case (98.5%). In one patient with severe vessel tortuosity, a successful balloon dilation was performed, but the stent could not be successfully advanced through the coronary artery to the left anterior descending, and could be retrieved without any complication. Changing to a larger size guiding catheter was not required in any patient. Balloon predilation was performed before coronary placement in 41 of the 66 stents (62.1%), whereas stents were directly implanted without balloon predilation in the remaining 25 cases (37.9%).

CONCLUSION

Coronary stenting through 5 French guiding catheters is feasible. This strategy may be especially indicated in patients with moderate-severe vessel tortuosity.

Differential effects of polysulphates between mouse and hamster during in vitro fertilization

The interaction between zona pellucida polysulphates and sperm receptors appears to be a widespread mechanism used by mammals during gamete interaction. In this work, the effect of heparin on binding, penetration and fertilization of mouse and hamster oocytes was assessed. We found that heparin inhibited oocyte penetration and fertilization in both species. Heparin as well as fucoidan (a fucose-sulphate polymer) inhibited the proteolytic activity of acrosomal enzymes in both species. Our results suggest that zona pellucida penetration in both species may be modulated by polysulphates acting on either the proteolytic rate of degradation of the zona and/or its interaction with acrosome-reacted sperm (secondary binding).

Intrapericardial beta-adrenergic blockade with esmolol exerts a potent antitachycardic effect without depressing contractility

Hyperadrenergic states of various etiologies can contribute to tachycardias. Systemic beta-adrenergic blockade suppresses sinus tachycardia but may adversely affect arterial blood pressure and contractility, because the drug gains access to myocardial cells as well as to the sinoatrial node. We examined whether intrapericardial beta-adrenergic blockade with esmolol could suppress tachycardia without reducing contractility as a result of limited drug diffusion, which would be sufficient to penetrate the superficial sinoatrial node but not the deeper myocardial layers. In five anesthetized pigs, we provoked a reflex heart rate increase of 50 beats/min with hemorrhage. The rapidly acting beta-adrenergic blocking agent esmolol (1 mg/kg) was administered intrapericardially using a new percutaneous transatrial access method and a catheter system that can be rapidly and safely introduced. Esmolol equivalently suppressed hemorrhage-induced sinus tachycardia when administered intrapericardially (from 192 to 158 beats/min at 5 min, p < 0.05) or intravenously (from 177 to 151 beats/min at 1 min, p < 0.05). The antitachycardic effect of intrapericardial esmolol was prolonged compared with intravenous esmolol (10 min vs. 3 min, p < 0.05). Intrapericardial esmolol did not affect blood pressure or left ventricular dP/dt max, an index of contractility, whereas intravenous esmolol decreased blood pressure at 1 min for 2 min (p < 0.05) and simultaneously decreased left ventricular dP/dt max at 1 min for < 2 min (p < 0.05). Intrapericardial esmolol suppresses adrenergically induced sinus tachycardia without decreasing contractility or blood pressure. The transatrial approach for intrapericardial delivery of certain 1-adrenergic blocking agents could be employed to control tachycardias in emergency care and surgical settings in patients with impaired cardiac contractility and propensity to hypotension.