Transaxillary Tri-Branch Aortic Endovascular Graft Repair of Recurrent Thoracoabdominal Aneurysm With Pararenal Aortic Occlusion

The absence of an adequate ileo-femoral access is usually considered an absolute contraindication to fenestrated and branched aortic repairs. Alternative routes and dedicated stent-graft designs have been advocated. Hereby, we describe the case of a 73-year-old man with a recurrent type IV thoracoabdominal aortic aneurysm and complete thrombotic pararenal aortic occlusion treated successfully with a tri-branch custom-made endograft deployed via a transaxillary access.

Staged endovascular treatment of aneurysmal progressive development of an intercostal arteries island reimplanted with the loop-graft technique

A staged endovascular strategy was used to treat the aneurysmal evolution of the aortic island including intercostal arteries reimplanted in a loop-graft, following thoraco-abdominal aortic open repair in a young patient diagnosed with Marfan syndrome. First, selective coil embolization of patent intercostal arteries was performed in 2 separate sessions, to minimize the risk of spinal cord ischaemia. Then, the aneurysm was successfully excluded occluding the loop graft with 2 PTFE-membrane vascular plugs.

Percutaneous Mechanical Thrombectomy of Atriocaval Floating Thrombus After Impella RP Removal in a Critically Ill Patient

The rapid institution of mechanical circulatory support (MCS) during cardiogenic shock secondary to severe biventricular failure is strongly recommended. Despite the introduction of less-invasive devices and adequate anticoagulation protocols, the presence of vascular complications in patients treated with MCS has not yet been eliminated. Here, the authors report a 60-year-old patient treated with the Bi-Pella approach for biventricular failure. Despite anticoagulant therapy, the patient developed a floating thrombosis in the inferior vena cava extending to the right atrium after the Impella RP removal. Considering the thrombus instability and the risk of pulmonary embolism, the patient was treated urgently for a percutaneous mechanical thrombectomy using the AngioJet thrombectomy system. The procedure was completed without intraoperative complications, and both the completion angiography and transesophageal echocardiography showed complete thrombus removal. No procedure-related complications occurred, but the patient died from progressive worsening of left ventricular failure on the 16th postoperative day. In the case of proximal extensive deep vein thrombosis with an increased risk of pulmonary embolism, the use of percutaneous mechanical thrombectomy could be a therapeutic option, even in critically ill patients, due to its minimally invasive nature and low rates of complications.

Incidence of deep venous thrombosis in COVID-19 hospitalized patients during the first peak of the Italian outbreak

OBJECTIVES

A high rate of thrombotic events has been reported in COVID-19 population. The study aims to assess the incidence of deep vein thrombosis (DVT) in COVID-19 patients admitted to a single tertiary hospital.

METHODS

From April 2nd to April 18th, 2020, hospitalized patients with SARS-CoV-2 infection were screened by lower limb duplex ultrasound (DUS). Patients were on (low molecular weight heparin) LMWH prophylaxis in medical wards, and on therapeutic anticoagulation in intensive care unit (ICU). DVT risk factors, reported by the Padua prediction score and blood tests, were retrieved from institutional electronic charts. The study primary endpoint was the incidence of DVT in the in-hospital COVID-19 population and its association with clinical and laboratory risk factors. The secondary endpoint was the association of DVT with mortality.

RESULTS

Two hundred patients (median age 62 years, 72% male, 40 in ICU) received DUS screening. DVT was observed in 29 patients (14.5%), with proximal extension in 16 patients, and in association with symptoms in four patients. The DVT rate was similar in ICU (12.5%) and non-ICU patients (15%). Eighty-seven patients underwent a computed tomography angiography (CTA) that showed pulmonary embolism in 35 patients (40.2%) not associated with DVT in 25/35 cases (71.4%). DVT in the ten patients with pulmonary embolism were symptomatic in four and with a proximal localization in eight cases. A D-dimer level ≥5 mg/l at admission was predictive of DVT (OR 1.02; IC95% 1.03-1.16; p  = .003). At the multivariate analysis in-hospital mortality was predicted by age (OR 1.06; 95% CI 0.02-1.15; p  = .004) and by being an ICU patient (OR 1.23; 95% CI 0.30-2.25; p  = .01).

CONCLUSIONS

Despite LMWH prophylaxis or full anticoagulant therapy, the incidence of DVT, mainly asymptomatic, in hospitalized COVID-19 patients was 14.5%. Further research should focus on the appropriate antithrombotic therapy for COVID-19 patients.

Giant Post-Traumatic Pseudoaneurysm of the Superficial Temporal Artery

Traumatism of head arteries is rare, but among them, the superficial temporal artery is the most exposed and less protected vessel. A pseudoaneurysm of the superficial temporal artery may occur after blunt head trauma in old patients or during vigorous activity in younger people. Diagnosis should be made primarily upon history and physical examination, while duplex ultrasound is appropriate to confirm the diagnosis and CT scan to exclude other possible concomitant pathologies. Direct surgical treatment is the first and main option to solve bleeding and prevent future complications. Here reported the case of an old woman treated for a post-traumatic STA pseudoaneurysm.

Neural Stem Cells from Shank3-ko Mouse Model Autism Spectrum Disorders

Autism spectrum disorders (ASD) comprise a complex of neurodevelopmental disorders caused by a variety of genetic defects and characterized by alterations in social communication and repetitive behavior. Since the mechanisms leading to early neuronal degeneration remain elusive, we chose to examine the properties of NSCs isolated from an animal model of ASD in order to evaluate whether their neurogenic potential may recapitulate the early phases of neurogenesis in the brain of ASD patients. Mutations of the gene coding for the Shank3 protein play a key role in the impairment of brain development and synaptogenesis in ASD patients. Experiments here reported show that NSCs derived from the subventricular zone (SVZ) of adult Shank3Δ11-/- (Shank3-ko) mice retain self-renewal capacity in vitro, but differentiate earlier than wild-type (wt) cells, displaying an evident endosomal/lysosomal and ubiquitin aggregation in astroglial cells together with mitochondrial impairment and inflammasome activation, suggesting that glial degeneration likely contributes to neuronal damage in ASD. These in vitro observations obtained in our disease model are consistent with data in vivo obtained in ASD patients and suggest that Shank3 deficit could affect the late phases of neurogenesis and/or the survival of mature cells rather than NSC self-renewal. This evidence supports Shank3-ko NSCs as a reliable in vitro disease model and suggests the rescue of glial cells as a therapeutic strategy to prevent neuronal degeneration in ASD.

Assessing the effects of biomechanical overload on dairy parlor workers' wrist: Definition of a study approach and preliminary results

BACKGROUND

Dairy milking is a demanding work task that has been associated with hand and wrist musculoskeletal disorders. Clinical approaches to identify the early effects of musculoskeletal disorders among dairy parlor workers' wrist have not been well defined.

OBJECTIVES

The purpose of this pilot study was to develop a study protocol that would assist in the identification and quantification of hand and wrist disorders among dairy workers that perform tasks in the dairy parlor. Additionally, such a study protocol was needed to perform relatively rapid assessments of the wrist/hand on large samples of dairy workers.

METHODS

Fourteen dairy parlor workers were assessed for i) upper limb symptoms and work history through questionnaire, ii) a physical examination of the upper limb and in particular wrists and iii) wrist ultrasonography. An additional 21 unexposed paired participants (the control group) also participated in the data collection.

RESULTS

The study results identified two ultrasound acoustic windows characterized by the highest predictive value for alteration of the wrist's structure. Study results indicated an impairment of the distal median nerve in structure and mobility and impairment of the distal tendon of the muscle extensor carpi ulnaris that included dislocation and frank damage.

CONCLUSIONS

This study identified at least two acoustic windows that should be assessed with ultrasound studies on larger groups and in prospective periodical health surveillance of dairy workers. The study confirmed the wrist was at risk for biomechanical stress among workers conducting milking tasks in the dairy parlors.

Cryopreserved Human Allografts for the Reconstruction of Aortic and Peripheral Prosthetic Graft Infection

Background: This study aimed to present cases with cryopreserved human allografts (CHAs) for vascular reconstruction in both aortic and peripheral infected prosthetic grafts.

Materials and Methods: This is a single center, observational descriptive study with retrospective analysis. In all cases, the infected prosthetic graft material was completely removed. At discharge, patients were administered anticoagulants. Follow-up examinations included clinical visits, echo-color-Doppler ultrasounds, or computed tomography angiography within 30 days and at 3, 6, and 12 months after the treatment, and then twice per year.

Results: We treated 21 patients (90% men, n=19) with the mean age of 71±12 years and mean interval between the initial operation and replacement with CHA of 30 months [range, 1–216; interquartile range (IQR), 2–36]. In-hospital mortality was 14% (n=3); no CHA-related complication led to death. Limb salvage was 100%. No patient was lost at the median follow-up of 14 months (range, 2–61; IQR, 6–39). No rupture, aneurysmal degeneration, or re-infection occurred. Estimated freedom from CHA-related adverse events (95% confidence interval, 43–63) was 95% at 3 years.

Conclusion: In our experience, CHAs are a viable option for prosthetic graft infections and provide satisfactory clinical results and favorable stability because of a very low rate of CHA-related adverse events during follow-up.

Delayed Graft Dislocation After Thoracic Aortic Endovascular Repair

Background Endograft dislocation in thoracic aorta has not been widely studied.Objectives The purpose of this study is to analyze the incidence and predisposing factor in a single centre experience after 117 procedures.Method Between November 2000 and December 2011, all consecutive patients undergoing endovascular repair for descending thoracic or thoraco-abdominal aortic disease were identified. Follow-up imaging protocol included triple-phase CT-angiography at 1, 4, and 12 months, and annually thereafter. Migration was defined as proximal/ distal movements >10 mm relative to anatomical landmarks or any movement leading to symptoms or reintervention.Result We identified 117 patients. Mean follow-up was 32 months (range, 1-144). Overall, five (4.3%) patients with thoracic EG dislocation were identified. Dislocation was classified as collapse/infolding in 3 cases and migration in 2. Mean delay of the dislocation was 12.7 months. Only one patient developed symptoms and required an additional endograft. In the group of dislocated endografts, mean age (53 ± 20 vs. 68 ± 15, P = .032) and the diameter of the aortic lesion were lower (4.1cm ± 1.6 vs. 5.6cm ± 1.8, P = .069), and the proximal landing zone at “zones 2 and 3” were more frequently used (5 vs. 65, P = 0.81). All but one patient with collapse/infolding are still alive and doing well at a mean follow-up of 80 months.Conclusion Dislocation is an infrequent complication, but not so rare. Young age, small aortic diameter , and proximal sealing at the distal arch were the most important data associated with this complication.Kathmandu University Medical Journal Vol.12(2) 2014: 97-100

An unusual case of stent migration after celiac trunk endovascular revascularization

A 61-year-old woman underwent celiac trunk stenting to treat abdominal angina. Three months later, she was readmitted for recurrent symptoms. Computed tomography control revealed the migration of the stent into the splenic artery. No sign of vessel injury or end-organ ischemia was detected. Repeat stenting of the celiac trunk was performed; the postoperative course was uneventful. 12 months later, the patient was asymptomatic with the second stent in its correct position, and she was asymptomatic for mesenteric ischemia.

Herniation of the gallbladder within a hernia of the abdominal wall associated with Mirizzi Syndrome

A gallbladder incarcerated hernia associated with Mirizzi syndrome is a very rare entity and to our knowledge this is the first case ever described in literature. An 85-year-old man presented at the emergency department with a tender right upper quadrant mass. Computed Tomography (CT) revealed the presence of a gallbladder lithiasis with signs of acute cholecystitis, herniated through the abdominal wall with an associated Mirizzi syndrome. Laparoscopic cholecystectomy and repair of the abdominal wall defect were performed. The patient recovered very well and the postoperative period was uneventful.

Mesenchymal stem cells support dorsal root ganglion neurons survival by inhibiting the metalloproteinase pathway

The positive effect of adult undifferentiated mesenchymal stem cells (MSCs) on neuronal survival has already been reported, although the mechanisms by which MSCs exert their effect are still a matter of debate. Here we have demonstrated that MSCs are able to prolong the survival of dorsal root ganglion (DRG) neurons mainly by inhibiting some proteolytic enzymes, and in particular the pathway of metalloproteinases (MMPs), a family of proteins that are involved in many neuronal processes, including survival. The inhibition of MMPs was both direct, by acting on MT-MMP1, and indirect, by acting on those proteins that regulate MMPs' activation, such as Timp-1 and Sparc. The importance of the MMPs' down-regulation for neuronal survival was also demonstrated by using N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycyl hydroxamic acid (NNGH), a wide range inhibitor of metalloproteinases, which was able to increase the survival of DRG neurons in a significant manner. The down-regulation of MMPs, obtained both by MSC contact and by chemical inhibition, led to the inactivation of caspase 3, the executor of apoptotic death in DRG neurons cultured alone, while caspase 7 was found to be irrelevant for the apoptotic process. The capacity of MSCs to prevent apoptosis mainly by inactivating the metalloproteinase pathway is an important finding that sheds light on MSCs' mechanism of action, making undifferentiated MSCs a promising tool for the treatment of many different neurodegenerative pathologies.

Neurophysiological and neuropathological characterization of new murine models of chemotherapy-induced chronic peripheral neuropathies

Cisplatin, paclitaxel and bortezomib belong to some of the most effective families of chemotherapy drugs for solid and haematological cancers. Epothilones represent a new family of very promising antitubulin agents. The clinical use of all these drugs is limited by their severe peripheral neurotoxicity. Several in vivo rat models have reproduced the characteristics of the peripheral neurotoxicity of these drugs. However, since only a very limited number of cancer types can be studied in immunocompetent rats, these animal models do not represent an effective way to evaluate, at the same time, the antineoplastic activity and the neurotoxic effects of the anticancer compounds. In this study, we characterized the neurophysiological impairment induced by chronic chemotherapy treatment in BALB/c mice, a strain suitable for assessing the activity of anticancer treatments. At the end of a 4-week period of treatment with cisplatin, paclitaxel, epothilone-B or bortezomib, sensory and sensory/motor nerve conduction velocities (NCV) were determined in the caudal and digital nerves and dorsal root ganglia (DRG) and sciatic nerves were collected for histopathological analysis. The electrophysiological studies revealed that all the compounds caused a statistically significant reduction in the caudal NCV, while impairment of the digital NCV was less severe. This functional damage was confirmed by the histopathological observations evidencing axonal degeneration in the sciatic nerve induced by all the drugs associated with pathological changes in DRG induced only by cisplatin and bortezomib. These results confirm the possibility to use our models to combine the study of the antineoplastic activity of anticancer drugs and of their toxic effects on the peripheral nervous system in the BALB/c mouse strain.

Human platelets express the synaptic markers VGLUT1 and 2 and release glutamate following aggregation

Vesicular glutamate transporters (VGLUTs) are involved in storing glutamate for secretion at the level of glutamatergic axon terminals, and for this reason they have been extensively used as markers to identify glutamate-releasing cells. Platelets have been considered as a suitable model for studying glutamatergic dysfunction because they perform glutamate uptake and express both external transporters, and NMDA-like receptors. Here, we show that platelets express the pre-synaptic markers VGLUT1 and VGLUT2 and release glutamate following aggregation, implying a possible contributory role in the pathophysiology of stroke, migraine, and other excitotoxic disorders.

Visualization of left atrial appendage and assessment of its function by transthoracic second harmonic imaging and contrast-enhanced pulsed Doppler

BACKGROUND

Low flow velocity within the left atrial appendage, as assessed by transoesophageal echocardiography, is a predictor of thromboembolism and of a low success rate of cardioversion of atrial fibrillation. However, the semi-invasive nature does limit its serial application as a screening technique.

METHODS AND RESULTS

We investigated the value of transthoracic second harmonic echocardiography and pulsed Doppler at baseline and after intravenous contrast injection to visualize the left atrial appendage and assess blood flow velocities within its cavity. We studied 51 consecutive patients undergoing transoesophageal echocardiography. After transoesophageal echocardiography, transthoracic second harmonic imaging was performed and the left atrial appendage was visualized in 46 patients. Interpretable pulsed Doppler tracings of left atrial appendage flow were obtained at baseline in 39 patients and in 45 patients during Levovist administration. The correlations between peak emptying velocity of left atrial appendage as measured by transoesophageal echocardiography and by transthoracic standard and contrast-enhanced Doppler were 0.81 and 0.91, respectively. The agreement between transoesophageal echocardiography and transthoracic contrast-enhanced pulsed Doppler echocardiography in classifying left atrial appendage flow velocity patterns was 93%. Left atrial appendage thrombus was detected by transthoracic second harmonic imaging in only one of the eight patients shown by transoesophageal echocardiography to have a thrombus. However, all but one of the patients with left atrial appendage thrombus and/or spontaneous echocardiographic contrast at transoesophageal echocardiography had <30cm/s left atrial appendage flow velocity by transthoracic Doppler.

CONCLUSIONS

This study shows that left atrial appendage can be visualized by transthoracic second harmonic imaging and that the flow velocity within its cavity is reliably measured by pulsed Doppler in a substantial fraction of patients. Contrast enhancement improves the feasibility and the accuracy of transthoracic evaluation of left atrial appendage flow velocity. The practical value of these results in predicting thromboembolic risk and success of cardioversion of atrial fibrillation needs to be proved by prospective studies.

Mechanics of the carotid artery wall and baroreflex sensitivity after acute ethanol administration in young healthy volunteers

The effects of ethanol administered orally (300 mg/kg in 250 ml of water) or intravenously (7.5 mg.min(-1).kg(-1) in 250 ml of saline over 40 min) on common carotid haemodynamics, wall mechanics and baroreflex sensitivity were compared with the effects of the intravenous infusion of 250 ml of saline. Ethanol or saline was administered to 10 healthy volunteers after 30 min of supine rest, and measurements were obtained 40 min (median; range 34-46 min) after administration. After ethanol administration, the plasma alcohol level rose from 0 to 0.3+/-0.07 g/l. Mean arterial blood pressure had risen slightly at 20 min, but was normalized by 40 min, the time at which the haemodynamic study was performed. Heart rate decreased after infusion of either saline or alcohol, but was unchanged after oral ethanol administration. Both oral and intravenous ethanol administration were associated with significant decreases in baroreflex sensitivity, carotid shear stress and blood velocity, compared with resting values, while the mean carotid artery diameter was increased, and blood viscosity and mean blood flow were unchanged. No changes were observed in these parameters after saline administration. Ethanol, administered either intravenously or orally, increased the stiffness of the carotid artery and decreased the pulsatility (systo-diastolic changes) of its diameter. A direct, statistically significant correlation was found between the decrease in shear stress and the decrease in baroreflex heart rate control sensitivity after both modes of alcohol administration, while no such correlation was found between the increase in the Peterson elastic modulus and the decrease in carotid diameter pulsatility on the one hand or the decrease in baroreflex sensitivity on the other. In conclusion, reduced shear stress associated with vasodilatation of the carotid artery wall may contribute to the decrease in baroreflex sensitivity observed after acute ethanol administration.

[Limits of cardiac functional adaptation in "top level" resistance athletes]

BACKGROUND

Sports activity, particularly when performed at high level, provokes cardiovascular adjustments depending on the type of sport and on the level of the load.

METHODS

We evaluated 15 athletes from the Italian national team during a non-agonistic period of cross country skiing, with non-invasive tests including exercise test, color Doppler echocardiography, Holter monitoring, physical examination and standard rest electrocardiogram.

RESULTS

Physical examination, rest electrocardiogram, exercise testing and echocardiography were all within the range of the expected values for this type of subjects. Holter monitoring recorded during the periods of agonistic activity revealed significant hypokinetic arrhythmias such as severe bradycardia, pauses, I and II degree atrioventricular blocks, and complete atrioventricular block in 2 cases; these features were not observed on Holter monitoring recorded during the non-agonistic period.

CONCLUSIONS

The perfect health status of subjects and their racing results may bring about physiological functional adjustments, but these observations suggest the need for a follow-up to evaluate possible pathologic outcomes.

Agrin controls synaptic differentiation in hippocampal neurons

Agrin controls the formation of the neuromuscular junction. Whether it regulates the differentiation of other types of synapses remains unclear. Therefore, we have studied the role of agrin in cultured hippocampal neurons. Synaptogenesis was severely compromised when agrin expression or function was suppressed by antisense oligonucleotides and specific antibodies. The effects of antisense oligonucleotides were found to be highly specific because they were reversed by adding recombinant agrin and could not be detected in cultures from agrin-deficient animals. Interestingly, the few synapses formed in reduced agrin conditions displayed diminished vesicular turnover, despite a normal appearance at the EM level. Thus, our results demonstrate the necessity of agrin for synaptogenesis in hippocampal neurons.

The GLT-1 and GLAST glutamate transporters are expressed on morphologically distinct astrocytes and regulated by neuronal activity in primary hippocampal cocultures

The GLT-1 and GLAST astroglial transporters are the glutamate transporters mainly involved in maintaining physiological extracellular glutamate concentrations. Defects in neurotransmitter glutamate transport may represent an important component of glutamate-induced neurodegenerative disorders (such as amyotrophic lateral sclerosis) and CNS insults (ischemia and epilepsy). We characterized the protein expression of GLT-1 and GLAST in primary astrocyte-neuron cocultures derived from rat hippocampal tissues during neuron differentiation/maturation. GLT-1 and GLAST are expressed by morphologically distinct glial fibrillary acidic protein-positive astrocytes, and their expression correlates with the status of neuron differentiation/maturation and activity. Up-regulation of the transporters paralleled the content of the synaptophysin synaptic vesicle marker p38, and down-regulation was a consequence of glutamate-induced neuronal death or the reduction of synaptic activity. Finally, soluble factors in neuronal-conditioned media prevented the down-regulation of the GLT-1 and GLAST proteins. Although other mechanisms may participate in regulating GLT-1 and GLAST in the CNS, our data indicate that soluble factors dependent on neuronal activity play a major regulating role in hippocampal cocultures.

The beta4 integrin interactor p27(BBP/eIF6) is an essential nuclear matrix protein involved in 60S ribosomal subunit assembly

p27(BBP/eIF6) is an evolutionarily conserved protein that was originally identified as p27(BBP), an interactor of the cytoplasmic domain of integrin beta4 and, independently, as the putative translation initiation factor eIF6. To establish the in vivo function of p27(BBP/eIF6), its topographical distribution was investigated in mammalian cells and the effects of disrupting the corresponding gene was studied in the budding yeast, Saccharomyces cerevisiae. In epithelial cells containing beta4 integrin, p27(BBP/eIF6) is present in the cytoplasm and enriched at hemidesmosomes with a pattern similar to that of beta4 integrin. Surprisingly, in the absence and in the presence of the beta4 integrin subunit, p27(BBP/eIF6) is in the nucleolus and associated with the nuclear matrix. Deletion of the IIH S. cerevisiae gene, encoding the yeast p27(BBP/eIF6) homologue, is lethal, and depletion of the corresponding gene product is associated with a dramatic decrease of the level of free ribosomal 60S subunit. Furthermore, human p27(BBP/eIF6) can rescue the lethal effect of the iihDelta yeast mutation. The data obtained in vivo suggest an evolutionarily conserved function of p27(BBP/eIF6) in ribosome biogenesis or assembly rather than in translation. A further function related to the beta4 integrin subunit may have evolved specifically in higher eukaryotic cells.

A cell-free system to study regulation of focal adhesions and of the connected actin cytoskeleton

Assembly and modulation of focal adhesions during dynamic adhesive processes are poorly understood. We describe here the use of ventral plasma membranes from adherent fibroblasts to explore mechanisms regulating integrin distribution and function in a system that preserves the integration of these receptors into the plasma membrane. We find that partial disruption of the cellular organization responsible for the maintenance of organized adhesive sites allows modulation of integrin distribution by divalent cations. High Ca2+ concentrations induce quasi-reversible diffusion of beta1 integrins out of focal adhesions, whereas low Ca2+ concentrations induce irreversible recruitment of beta1 receptors along extracellular matrix fibrils, as shown by immunofluorescence and electron microscopy. Both effects are independent from the presence of actin stress fibers in this system. Experiments with cells expressing truncated beta1 receptors show that the cytoplasmic portion of beta1 is required for low Ca2+-induced recruitment of the receptors to matrix fibrils. Analysis with function-modulating antibodies indicates that divalent cation-mediated receptor distribution within the membrane correlates with changes in the functional state of the receptors. Moreover, reconstitution experiments show that purified alpha-actinin colocalizes and redistributes with beta1 receptors on ventral plasma membranes depleted of actin, implicating binding of alpha-actinin to the receptors. Finally, we found that recruitment of exogenous actin is specifically restricted to focal adhesions under conditions in which new actin polymerization is inhibited. Our data show that the described system can be exploited to investigate the mechanisms of integrin function in an experimental setup that permits receptor redistribution. The possibility to uncouple, under cell-free conditions, events involved in focal adhesion and actin cytoskeleton assembly should facilitate the comprehension of the underlying molecular mechanisms.

Complete atrioventricular block with unwidened QRS complex during hyperkalemia

Purkinje and ventricular myocardial fibers are thought to be more sensitive to hyperkalemia than sinoatrial and atrioventricular (AV) nodes, although complete AV block due to hyperkalemia can occur. We describe a case in which hyperkalemia in a patient affected by renal failure is responsible for complete AV block without QRS complex prolongation. Temporary endoventricular pacing was essential in restoration of adequate renal blood flow and excretion of exceeding serum potassium with subsequent normalization of AV conduction.

Systemic thrombolysis for acute myocardial infarction in a renal transplant recipient

This study describes the successful management of an acute myocardial infarction occurring in a renal transplant recipient with thrombolytic therapy. Although primary coronary angioplasty has been addressed as an alternative therapeutic approach, this approach raises concern for angiography-related contrast media renal toxicity. However, pharmacological therapy with thrombolytics is effective and relatively safe and should be considered as the first-choice treatment in today's clinical setting.

Loose-patch recordings of single quanta at individual hippocampal synapses

Synapses in the central nervous system are typically studied by recording electrical responses from the cell body of the postsynaptic cell. Because neurons are normally connected by multiple synaptic contacts, these postsynaptic responses reflect the combined activity of many thousands synapses, and it remains unclear to what extent the properties of individual synapses can be deduced from the population response. We have therefore developed a method for recording the activity of individual hippocampal synapses. By capturing an isolated presynaptic bouton inside a loose-patch pipette and recording from the associated patch of postsynaptic membrane, we were able to detect miniature excitatory postsynaptic currents ('minis') arising from spontaneous vesicle exocytosis at a single synaptic site, and to compare these with minis recorded simultaneously from the cell body. The average peak conductance at a single synapse was about 900 pS, corresponding roughly to the opening of 90 AMPA-type glutamate-receptor channels. The variability in this conductance was about 30%, matching the value reported for the neuromuscular junction. Given that our synapses displayed single postsynaptic densities (PSDs), this variability is larger than would be predicted from the random opening of receptor channels, suggesting that they are not saturated by the content of a single vesicle. Therefore the response to a quantum of neurotransmitter at these synapses is not limited by the number of available postsynaptic receptors.

High-resolution calcium mapping of the endoplasmic reticulum-Golgi-exocytic membrane system. Electron energy loss imaging analysis of quick frozen-freeze dried PC12 cells

The calcium pools segregated within the endoplasmic reticulum, Golgi complex, exocytic, and other organelles are believed to participate in the regulation of a variety of cell functions. Until now, however, the precise intracellular distribution of the element had not been established. Here, we report about the first high-resolution calcium mapping obtained in neurosecretory PC12 cells by the imaging mode of the electron energy loss spectroscopy technique. The preparation procedure used included quick freezing of cell monolayers, followed by freeze-drying, fixation with OSO4 vapors, resin embedding, and cutting of very thin sections. Conventional electron microscopy and high-resolution immunocytochemistry revealed a high degree of structural preservation, a condition in which inorganic elements are expected to maintain their native distribution. Within these cells, calcium signals of nucleus, cytosol, and most mitochondria remained below detection, whereas in other organelles specific patterns were identified. In the endoplasmic reticulum, the distribution was heterogeneous with strongly positive cisternae (more often the nuclear envelope and stacks of parallel elements that are frequent in quick frozen preparations) lying in the proximity of or even in direct continuity with other, apparently negative cisternae. The Golgi complexes were labeled strongly and uniformly in all cisternae and part of their vesicles, with no appreciable differences along the cis-trans axis. Weaker or negative signals were recorded from the trans-Golgi network elements and from scattered vesicles, whereas in contrast secretion granules were strongly positive for calcium. These results are discussed in relation to the existing knowledge about the mechanisms of calcium transport in the variations organelles, and about the processes and functions regulated by organelle lumenal calcium in eukaryotic cells.

[Isolated cardiac amyloidosis. Presentation of a clinical case]

A 48-year old patient affected by congestive heart failure came to our observation for cardiac arrest due to ventricular fibrillation. After cardiopulmonary resuscitation and defibrillation he underwent complete evaluation. Echo Doppler findings were consistent with restrictive cardiomyopathy. Laboratory findings revealed monoclonal gammopathy and plasma cells dyscrasia. Diagnosis of amyloidosis was then suspected and biopsies of different organs and tissues were performed. Presence of amyloid deposits was found only in myocardial specimens from the right ventricle. Medical treatment with drugs of various classes, administered during hemodynamic invasive monitoring, was uneffective in improving the hemodynamic and clinical status of the patient and he entered in a heart transplantation list. He died six months later, while awaiting for transplantation. Although isolated cardiac amyloidosis is quite rare, we believe that this condition has ever to be kept in mind during differential diagnosis of restrictive cardiomyopathies and we remark that endomyocardial biopsy was mandatory and necessary for certain diagnosis in this case; in addition, the unefficacy of drugs nowadays available for treatment of congestive heart failure in amyloid cardiomyopathy is confirmed.

High resolution ultrastructural mapping of total calcium: electron spectroscopic imaging/electron energy loss spectroscopy analysis of a physically/chemically processed nerve-muscle preparation

We report on a procedure for tissue preparation that combines thoroughly controlled physical and chemical treatments: quick-freezing and freeze-drying followed by fixation with OsO4 vapors and embedding by direct resin infiltration. Specimens of frog cutaneous pectoris muscle thus prepared were analyzed for total calcium using electron spectroscopic imaging/electron energy loss spectroscopy (ESI/EELS) approach. The preservation of the ultrastructure was excellent, with positive K/Na ratios revealed in the fibers by x-ray microanalysis. Clear, high-resolution EELS/ESI calcium signals were recorded from the lumen of terminal cisternae of the sarcoplasmic reticulum but not from longitudinal cisternae, as expected from previous studies carried out with different techniques. In many mitochondria, calcium was below detection whereas in others it was appreciable although at variable level. Within the motor nerve terminals, synaptic vesicles as well as some cisternae of the smooth endoplasmic reticulum yielded positive signals at variance with mitochondria, that were most often below detection. Taken as a whole, the present study reveals the potential of our experimental approach to map with high spatial resolution the total calcium within individual intracellular organelles identified by their established ultrastructure, but only where the element is present at high levels.

Expression of muscle calsequestrin in epithelial HeLa cells: distribution and functional role

Calsequestrin is a Ca2+ binding protein expressed by a few cell types (mostly muscle fibers). In these cells the distribution of the protein is within the endoplasmic/sarcoplasmic reticulum, however, not uniformly throughout but at discrete sites of the lumen. In order to investigate the mechanisms of this unusual intracellular distribution together with the possible functions of the protein, we have studied stable transfected clones of epithelial HeLa cells. Treatment of these cells with butyric acid induced a rapid (24 h) and massive (approx. 10-fold) increase of the transfected protein, whereas the other lumenal and membrane proteins of the endoplasmic reticulum were either modified slightly or unchanged. When butyric acid treatment was interrupted the calsequestrin levels returned rapidly (within 24 h) to the pre-treatment level. Such a rapid turnover was due in part to secretion, sustained by both spontaneous and Ca(2+)-dependent release of calsequestrin to the extracellular medium. From the physiological point of view, the transfected cells exhibited only moderate increases of the Ca2+ release responses triggered by either ATP (a ligand addressed to the P2u receptor and working through IP3 generation) or thapsigargin (a blocker of the endoplasmic reticulum Ca2+ ATPase), with no further increase after butyric acid induction of calsequestrin. This result appears to correlate with the occurrence of only small amounts of calsequestrin within the endoplasmic reticulum lumen of all transfected cells. The bulk of calsequestrin, in contrast, was found sequestered within large vacuoles distributed both near the cell surface and, after butyric acid treatment, also in the deep cytoplasm. These vacuoles (possibly a lysosomal subcompartment) appear to contain no Ca2+ as no difference in 45Ca release from transfected cells was observed without or with butyric acid pretreatment when exposed to ionomycin, alone or combined with monensin. We conclude that HeLa cells possess no adequate mechanisms to keep calsequestrin in its physiologically relevant location, the endoplasmic reticulum. In the transfected cell the protein seems therefore to be diverted (possibly by default) to vacuoles destined to be rapidly eliminated by the cell.

Modifications in a flexible surface loop modulate the isozyme-specific properties of mammalian alkaline phosphatases

We have analyzed to what extent the surface loop domain of alkaline phosphatases (APs) is responsible for isozyme-specific functional properties. Unique AatII and RsrII restriction sites were introduced by site-directed mutagenesis at identical positions in murine tissue-nonspecific AP (TNAP) and human placental AP (PLAP) cDNAs to allow the homologous exchange of the loop domain of the TNAP (T domain) and PLAP (P domain) isozymes and the generation of the reciprocally chimeric molecules PLAP-T and TNAP-P. The introduction of the T loop into PLAP reduced the heat stability of PLAP-T to almost that of TNAP. The domain substitution was accompanied by a conformational change that resulted in the loss of immune reactivity with four of 17 epitope-mapped anti-PLAP monoclonal antibodies. The T and P loops provided stabilization to the side chain of specific uncompetitive AP inhibitors. The introduction of the T domain also conferred collagen-binding properties to PLAP-T accounting for half of the binding affinity of TNAP for collagen, while not affecting PLAP binding to IgG. Our data indicate that the surface loop determines overall enzyme stability, differs conformationally in the various isozymes, and modulates catalytic parameters in the presence of protein ligands, thus, accounting in part for isozyme-specific protein interactions.

Pregnancy-associated plasma protein B (PAPP-B): isolation from human late pregnancy serum and biochemical characterization

The pregnancy associated plasma protein B (PAPP-B) was first described by Lin et al. as a glycoprotein with a molecular weight of about 1,000 kD and a serum half life of less than 24 hours after delivery. We isolated PAPP-B from late pregnancy serum using liquid chromatography including HPLC. PAPP-B was found to be a glycoprotein with a molecular weight of 1,300 kD and to be an octadecamer of identical subunits (74 kD each). Cleavage of the carbohydrates with trifluoromethanesulfonic acid reduced the molecular mass to 65 kD (by SDS PAGE, 12.2%). Isoelectrofocusing and titration curves fixed the isoelectric point at 5.3. Spectroscopy measurements between 230 and 360 nm yielded a trp/tyr ratio of 1.1. Amino acid analysis showed that each subunit contained five methionines; this was confirmed by a CNBr cleavage experiment.

Synapsin I partially dissociates from synaptic vesicles during exocytosis induced by electrical stimulation

The distribution of the synaptic vesicle-associated phosphoprotein synapsin I after electrical stimulation of the frog neuromuscular junction was investigated by immunogold labeling and compared with the distribution of the integral synaptic vesicle protein synaptophysin. In resting terminals both proteins were localized exclusively on synaptic vesicles. In stimulated terminals they appeared also in the axolemma and its infoldings, which however exhibited a lower synapsin I/synaptophysin ratio with respect to synaptic vesicles at rest. The value of this ratio was intermediate in synaptic vesicles of stimulated terminals, and an increased synapsin I labeling of the cytomatrix was observed. These results indicate that synapsin I undergoes partial dissociation from and reassociation with synaptic vesicles, following physiological stimulation, and are consistent with the proposed modulatory role of the protein in neurotransmitter release.

[The emergency treatment of supraventricular tachyarrhythmias: the efficacy and safety of intravenous propafenone]

One hundred patients, admitted to the Emergency Unit for paroxysmal supraventricular tachycardia (SVT) with 1:1 AV conduction, atrial fibrillation (af) and flutter (AF) of recent onset (less than 72 hours) were treated with intravenous propafenone (P). The drug was administered at the dose of 70 mg over 5 min, repeated after 10 min if sinus rhythm (SR) was not restored and eventually followed by continuous infusion (0.35-0.50 mg/min) until conversion to SR or during the next 48 hours. Exclusion criteria were ventricular rate < 100/min, R-R intervals > 1 s, clinical signs of heart failure or asthma. Termination of SVT within 30 min was obtained in 94% of the patients, while reversion to SR occurred in 79% with af and in 55% with AF. For af and AF conversion was achieved within 30 min in 49% of overall responders (R), between 30 min and 6 hours in 27% and between 6 hours and 48 hours in 24%. The efficacy of P was significantly influenced by the duration of arrhythmia and left atrial size, measured by 2D-echocardiography. On the contrary, no difference was observed between R and non-R in mean age and in the percentage of primary or relapsing arrhythmias. Adverse effects were encountered in 7 patients: in 1 case worsened arrhythmia and in 6 patients, with long-lasting arrhythmias, congestive heart failure. Neither conduction disturbance nor extra-cardiac complications occurred. In conclusion, P provides effective and safe treatment for paroxysmal atrial tachyarrhythmias, so that it can be considered among the drugs of first choice even in non-intensive care units.

Reflex cardiovascular control in congestive heart failure

This article reviews evidence that the reflex control of the cardiovascular system provided by negative feedback mechanisms is impaired in congestive heart failure (CHF). The impairment involves vagal and sympathetic modulation of the heart exerted by arterial baroreceptors. It also affects baroreceptor control of blood pressure and peripheral vascular resistance, as well as the cardiopulmonary receptor's ability to modulate sympathetic activity. The degree of such impairment is most marked in severe CHF but is also apparent, to a minor degree, in mild heart failure. Reflex impairment is due to a reduction in the receptor signal, but other factor under investigation are probably also involved. Digoxin and other pharmacologic treatments of CHF improve reflex function, thereby facilitating a reduction in the elevated sympathetic activity and a stepping up of the reduced vagal activity typical of CHF. This may be relevant to a patient's prognosis.

Functional evaluation 10 days and 3 weeks after acute myocardial infarction: comparative significance and prognostic value

Early functional evaluation after non-complicated acute myocardial infarction (AMI) is widely recommended because of its prognostic value in the short term. In fact it seems to have a prognostic value within 15-20 days of the AMI, but in this period the patient is particularly controlled and is often still hospitalized. To evaluate the real significance of an early functional evaluation within 10 days of the AMI (mean 8.6 days +/- 1.2) as compared to an identical functional evaluation performed at 3 weeks after AMI (mean 20.16 days +/- 5.38) 25 patients with uncomplicated myocardial infarction were studied. Significant statistical differences were found between the first (ET1) and second (ET2) functional evaluations: they concern the maximal heart rate reached (P less than 0.001), the maximal pressure-rate product (P less than 0.05), the percentage increment of heart rate (P less than 0.01) and the total work performed (P less than 0.001). Agreement between ET1 and ET2 was found in 19 cases; 12 patients showed markers of ischaemia both at ET1 and ET2, while seven were free from ischaemia at both times. In six cases a disagreement between ET1 and ET2 was found: in particular, three cases had ischaemic ET1 and nonischaemic ET2; the reverse was seen in the other three. During follow-up (mean 215.4 days +/- 85.5), the total number of new events (reinfarctions, angina or surgery) among the 25 patients was eight; none occurred within the first 30 days after the AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin by alternative routes of administration

In a study investigating the bioavailability of heparin administered by different routes, we also compared its bioavailability in the dog after oral administration of two enteric-coated formulations, one containing a heparin preparation (ITF-300) and the other sodium heparin. After administration of the formulation containing sodium heparin, there was no heparin in plasma, but when the formulation containing ITF-300 was given, plasma heparin levels were detectable.