Risk Factors for Postoperative Complications After Surgical Treatment of Type B and C Injuries of the Thoracolumbar Spine

BACKGROUND

Unstable thoracolumbar spinal injuries benefit from surgical fixation. However, perioperative complications significantly affect outcomes in surgicallytreated spine patients. We evaluated associations between risk factors and postoperative complications in patients surgically treated for thoracolumbar spine fractures.

METHODS

We conducted a retrospective multicenter study collating data from 21 spine centers across 9 countries on the treatment of AOSpine types B and C injuries of the thoracolumbar spine treated via a posterior approach. Comparative analysis was performed between patients with postoperative complications and those without. Univariate and multivariable analyses were performed.

RESULTS

Among 535 patients, at least 1 complication occurred in 43%. The most common surgical complication was surgical-site infection (6.9%), while the most common medical complication was urinary tract infection (13.8%). Among 136 patients with American Spinal Injury Association (ASIA) Impairment Scalelevel A disability, 77.9% experienced at least 1 complication. The rate of complications also rose sharply among patients waiting >3 days for surgery (P<0.001), peaking at 68.4% among patients waiting ≥30 days. On multivariable analysis, significant predictors of complications were surgery at a governmental hospital (odds ratio = 3.38, 95% confidence interval = 1.73-6.60), having ≥1 comorbid illness (2.44, 1.61-3.70), surgery delayed due to health instability (2.56, 1.50-4.37), and ASIA Impairment Scalelevel A (3.36, 1.78-6.35), while absence of impairment (0.39, 0.22-0.71), ASIAlevel E (0.39, 0.22-0.67) and, unexpectedly, delay caused by operating room unavailability (0.60, 0.36-0.99) were protective.

CONCLUSIONS

Types B and C thoracolumbar spine injuries are associated with a high risk of postoperative complications, especially common at governmental hospitals, and among patients with comorbidity, health instability, longer delays to surgery, and worse preoperative neurologic status.

Metabolically healthy obesity in a young population assisted by the Family Health Strategy in Brazil

Background

Obesity is increasing in younger populations, and is associated with a high cardiovascular (CV) risk, however, it is not clear whether metabolically healthy obesity (MHO) may have a lower CV risk or if it is just an earlier stage of the disease.

Objective

To evaluate the prevalence and CV risk factors associated with MHO in a young population assisted by a Family Health Care unit in a large urban center in Brazil.

Methods

A cross-sectional population study for CV risk assessment in adults aged 20-50 years old from a FHC unit in Rio de Janeiro. Demographic, anthropometric data and CV risk factors were recorded. All underwent office blood pressure (OBP) measurements, laboratory evaluation (lipid and glycidic profile). Obesity was defined as a BMI ≥ 30 kg/m2 and MHO are those who have less than 3 of the following criteria: hypertension, diabetes, total cholesterol ≥ 200 mg/dL, HDL&lt;40 mg/dL (men) and 50 mg/dL (women), triglycerides&gt;150 mg/dL and increased waist circumference.

Results

A total of 632 individuals were evaluated (60% female; mean age 37 ± 9 years). The prevalence of obesity was 26%, of which 73% were classified as MHO. Obeses are older, with a higher prevalence of physical inactivity (51% vs 41%, p = 0.03), hypertension (44% vs 19%, p &lt; 0.001), dyslipidemia (50% vs 36%, p = 0.002) and diabetes (7% vs 2%, p = 0.001) with higher systolic OBP. MHO compared to unhealthy ones are significantly younger and smoke less. Despite being obese, they have lower BMI (33.6 vs 35.2 kg/m2, p = 0.02) and abdominal circumference (102 vs 110 cm, p = 0.03), with lower diastolic BP.

Conclusions

MHO was more prevalent in this young population and seems to have a lower CV risk, however it is not clear whether these younger and less obese individuals are only at an earlier stage of the disease. Perhaps the CV diseases onset is postponed for a few years. Even so, these individuals should not be excluded from public health policies as a form of primary prevention.

Key messages

In this young population, MHO was more prevalent and presented a lower CV risk. The follow-up of MHO will show if they are really healthy or if they are at an early stage of the disease.

Investigating the effect of germanium on the structure of SiO2-ZnO-CaO-SrO-P2O5 glasses and the subsequent influence on glass polyalkenoate cement formation, solubility and bioactivity

A series of germanium (Ge)-containing glasses were synthesized based on a starting glass composition of SiO₂-ZnO-CaO-SrO-P₂O₅. Additions of GeO₂ (6 and 12 mol%) were incorporated at the expense of SiO_2, which retained the amorphous character, and each glass was processed to present similar particle size and surface area. Glass characterization using x-ray photoelectron spectroscopy (XPS) and magic angle spinning nuclear magnetic resonance (MAS-NMR) determined that the addition of GeO₂ increased the fraction of lower Q-speciation and subsequently the concentration of non-bridging oxygens (NBO). Glass Polyalkenoate Cements (GPC) were formulated from each glass with 40, 50 and 60 wt% PAA, and presented time dependent solubility profiles (1, 10, 100, 1000 h) for the release of Si⁴⁺ (4-140 mg/l), Ca²⁺ (1-8 mg/l), Zn²⁺ (<6 mg/l), Sr²⁺ (2-37 mg/l), PO₄^3- (2-43 mg/l) and Ge⁴⁺ (20-911 mg/l) and attained pH values close to 7.5 after 1000 h. Ge-GPCs containing 40 wt% polyacrylic acid (PAA) presented appropriate working time (T_w) and setting times (T_s), and the corresponding compressive strengths ranged from (14-30 MPa). The Ge-GPCs (40, 50 wt%) presented a linear increase (R²-0.99) with respect to time. Simulated Body Fluid (SBF) testing resulted in the Ge-GPCs encouraging the precipitation of crystalline hydroxyapatite on the GPC surface, more evidently after 100 and 1000 h incubation.

Comparison between different epidural analgesia modalities for labor

INTRODUCTION

In recent years new modalities of epidural analgesia maintenance (EA) have been introduced.

OBJECTIVE

The objective of this study is to compare different modalities of EA maintenance for childbirth relating the time of expulsive and dilatation, motor blockade and delivery instrumentation (caesarean section, sucker, forceps, eutocic delivery or non-instrumented delivery).

MATERIAL AND METHODS

Patients admitted for labor in the University Hospital Nuestra Señora de Candelaria between January 2013 and December 2015 were included. Independent modalities of EA, continuous infusion (CI), continuous infusion plus analgesia patient controlled epidural analgesia were determined as independent variables (CI+PCEA) and intermittent programmed epidural boluses plus patient controlled epidural analgesia (PIEB+PCEA).

RESULTS

There are no differences in expulsive time or dilation. There is a difference in the type of instrumentation, caesarean section, sucker, forceps, eutocic delivery or non-instrumented delivery (P>.05), with the percentage of eutocic deliveries in PIEB+PCEA of 66 versus 60 in CI and 65 in CI+PCEA. The percentage of caesarean sections was 23 in CI, in CI+PCEA and PIEB+PCEA of 17. CI increases by 27% the possibility of instrumented deliveries respect to PIEB+PCEA, there is no difference between CI+PCEA and PIEB+PCEA. The motor blockade at 60 and 90minutes reaches lower values with PIEB+PCEA with an average of 0 and a range of 0-1, compared to CI+PCEA 0 (0-4). Satisfaction with CI+PCEA ranges from 2-10 and with PIEB+PCEA 0-10.

CONCLUSION

It is possible to say that PIEB+PCEA is associated with higher frequency of non-instrumented deliveries. The possibility of instrumented deliveries increases with CI versus PIEB+PCEA. There is less motor block with PIEB+PCEA than with CI+PCEA. There are no differences in time of dilatation, expulsion, or patient satisfaction.

In vitro susceptibility and multilocus sequence typing of Fusarium isolates causing keratitis

Fungal keratitis is recognized as a significant cause of ocular morbidity and blindness especially in developing countries. In this study, we aimed to present the molecular identification and susceptibility of Fusarium isolates causing fungal keratitis in a university hospital in southern Brazil. The samples were identified using the second largest subunit of the RNA polymerase gene (RPB2) and the translation elongation factor 1-alpha (TEF1), while the antifungal susceptibility was tested by the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) methodology. The majority of the isolates belonged to the Fusarium solani species complex (F. solani, F. keratoplasticum and F. falciforme) and Fusarium oxysporum species complex. Antifungal susceptibility has shown that amphotericin B and natamycin were the most effective antifungals across all isolates, followed by voriconazole. Variation among Fusarium complexes in their antifungal sensitivities was observed in our study. The identification of Fusarium species from human samples is important not only from an epidemiological viewpoint, but also for choosing the appropriate antifungal agent for difficult-to-treat Fusarium infections such as keratitis.

Larval development and allometric growth of the black-faced blenny Tripterygion delaisi

Larval development and allometric growth patterns of the black-faced blenny Tripterygion delaisi are described from a larval series (body length, L_B  = 3·30-12·10 mm) caught by light traps at the Arrábida Marine Park, Portugal. Larvae of T. delaisi possess distinctive morphometric and meristic characteristics which can be used to identify this species from related taxa. Pigmentation is sparse but characteristic, consisting of pigmented eyes, gas bladder pigmentation in the dorsal region, anal pigmentation and a row of regularly spaced postanal ventral melanophores. This pattern is present from as early as the yolk-sac stage and persists throughout all stages with just the addition of head and caudal pigmentation during the flexion and postflexion stages, respectively. The majority of fin development (with the exception of the caudal fin), occurs in the later stages of development. Myomere counts range between 37 and 45 for all stages. Growth is allometric during larval development. When inflexion points of growth were detected, growth was found to be biphasic with the inflexion points occurring within a very narrow range of L_B (8·70-8·90 mm) close to the mean ± s.d. (9·44 ± 1·48 mm L_B ) of postflexion larvae. Considering allometric growth patterns and ontogenetic descriptions together, the first developmental phase includes the preflexion and flexion stage larvae, while the second phase characterises the postflexion larvae prior to the transition from larvae to juvenile.

Critical swimming speeds of wild-caught sand-smelt Atherina presbyter larvae

Swimming abilities of wild-caught sand-smelt Atherina presbyter larvae were assessed as critical swimming speed (Ucrit ) throughout ontogeny. The mean Ucrit increased with size, ranging from 3·6 to 18·7 cm s(-1) , over the size range of 6·6-21·0 mm LT . This indicates that at hatching A. presbyter larvae, far from being passive floaters, are already capable of active behaviours, which may influence their dispersal patterns.

Zinner's syndrome: an up-to-date review of the literature based on a clinical case

The authors made an up-to-date review of the literature concerning the management of Zinner's syndrome and evaluated a young patient with Zinner's syndrome who had presented with urinary and ejaculatory complaints. Physical examination and transrectal ultra-sonography showed a 7.0 cm right seminal vesicle cyst. Magnetic resonance imaging (MRI) confirmed the diagnosis of Zinner's syndrome. Oligoasthenoteratozoospermia was present at the two seminal analyses. Symptomatic improvement was achieved with conservative measures. Actually, the patient is still on a follow-up programme. The diagnosis is usually established at the age of increased sexual activity. Patients may be asymptomatic or present pain, irritative urinary or ejaculatory symptoms and infertility. MRI has proved to be the best imaging examination. Treatment should be adapted to symptoms, surveillance being the best option in the absence of clinical manifestations. Surgical approach may be adequate when conservative measures prove ineffective. Zinner's syndrome should be suspected if a male young patient presents with unilateral renal agenesis and pelvic complaints and has a supraprostatic mass on digital rectal examination. The initial approach should be medical, but invasive procedures may be the only way to solve the patient's complaints. Nowadays, laparoscopic and robotic techniques must replace the open surgical approach.

Measuring secretion in chromaffin cells using electrophysiological and electrochemical methods

Our present understanding of exocytosis of catecholamines has benefited tremendously from the arrival of single-cell electrochemical methods (amperometry and voltammetry), electrophysiological techniques (whole-cell and patch capacitance) and from the combination of both techniques (patch amperometry). In this brief review, we will outline the strengths and limitations of amperometric and electrophysiological methods and highlight the major contribution obtained with the use of these techniques in chromaffin cells.

Histogenesis and morphofunctional characteristics of chromaffin cells

This article reviews the current status of research about the histogenesis and morphofunctional characteristics of chromaffin cells in the adrenal medulla. First, this study reports the selective migration, transcription and activation factors, and the morphological events of the chromaffin cell precursors during adrenal medulla development. Subsequently, the morphofunctional characteristics of adrenergic and non-adrenergic cells are considered, with particular reference to the characteristics of chromaffin granules and their biological steps, including their formation, traffic (storage, targeting and docking), exocytosis in the strict sense and recapture. Moreover, the relationship of chromaffin cells with other tissue components of the adrenal medulla is also revised, comprising the ganglion cells, sustentacular cells, nerves and connective-vascular tissue.

Chronic hypoxia up-regulates alpha1H T-type channels and low-threshold catecholamine secretion in rat chromaffin cells

alpha(1H) T-type channels recruited by beta(1)-adrenergic stimulation in rat chromaffin cells (RCCs) are coupled to fast exocytosis with the same Ca(2+) dependence of high-threshold Ca(2+) channels. Here we show that RCCs exposed to chronic hypoxia (CH) for 12-18 h in 3% O(2) express comparable densities of functional T-type channels that depolarize the resting cells and contribute to low-voltage exocytosis. Following chronic hypoxia, most RCCs exhibited T-type Ca(2+) channels already available at -50 mV with the same gating, pharmacological and molecular features as the alpha(1H) isoform. Chronic hypoxia had no effects on cell size and high-threshold Ca(2+) current density and was mimicked by overnight incubation with the iron-chelating agent desferrioxamine (DFX), suggesting the involvement of hypoxia-inducible factors (HIFs). T-type channel recruitment occurred independently of PKA activation and the presence of extracellular Ca(2+). Hypoxia-recruited T-type channels were partially open at rest (T-type 'window-current') and contributed to raising the resting potential to more positive values. Their block by 50 microm Ni(2+) caused a 5-8 mV hyperpolarization. The secretory response associated with T-type channels could be detected following mild cell depolarizations, either by capacitance increases induced by step depolarizations or by amperometric current spikes induced by increased [KCl]. In the latter case, exocytotic bursts could be evoked even with 2-4 mm KCl and spike frequency was drastically reduced by 50 microm Ni(2+). Chronic hypoxia did not alter the shape of spikes, suggesting that hypoxia-recruited T-type channels increase the number of secreted vesicles at low voltages, without altering the mechanism of catecholamine release and the quantal content of released molecules.

[Multiple schwannoma of the penis]

Schwannoma or neurilemmoma designate a tumour that originates in the Schwann cells of peripheral nerves, therefore occurring anywhere in the body. They are very rare in the penis. In the literature are reported twenty seven cases of penile schwannoma. We report a case of multiple schwannoma of the penis and make a brief literature revision about this rare pathology.

Immunotherapy of american cutaneous leishmaniasis in Venezuela during the period 1990-99

Of a total of 11532 Venezuelan patients with American cutaneous leishmaniasis (ACL) receiving immunotherapy with a combined vaccine containing heat-killed Leishmania promastigotes and bacille Calmette-Guerin (BCG) during the period 1990-99, we evaluated 5341 from 4 widely separated geographical states. Clinical healing varied from 91.2 to 98.7%, with an average of 95.7%. Adverse reactions were mild and limited to those associated with BCG vaccination alone. Immunotherapy failures in 143 patients included 54.5% with typical localized ulcers and 45.5% with non-mucosal intermediate cutaneous leishmaniasis (ICL). Less than 2% of the patients in this study had lesions suggestive of ICL. The disproportionately large number of immunotherapy failures in the ICL group suggests that it should not be used as monotherapy in this group. Weaker reactivity to purified protein derivative in immunotherapy failures, while not statistically significant in the small group reported here, suggests the possibility that these patients develop a relatively torpid immune response. The high percentage of clinical cures achieved with immunotherapy, associated with few secondary effects and low cost, support the use of immunotherapy in the routine treatment of localized ACL.

The rat adrenal gland in the study of the control of catecholamine secretion

Catecholamine secretion in the rat can be studied in freely moving and anaesthetized animals, in isolated-perfused adrenals, medullae slices and isolated cultured cells. In addition the rat offers the advantage over the more widely used bovine adrenal model that researchers can have access to animals of the same age, sex and feeding conditions. Catecholamine release is similar to other species although it gives robust secretion in response to stimuli such as muscarinic agonists, bradykinin or VIP. It also allows the study of neurotransmission at the splanchnic-adrenal synapse. The use of single-cell preparations (patch-clamp, microfluorimetry, amperometry or capacitance) has overcome the limitations of the number of cells obtained from a gland. It is possible to study secretion in animal models of hypertension, chronic stress or diabetes and rats can be genetically modified.

[Exocytosis as the mechanism for neural communication. A view from chromaffin cells]

Exocytosis constitutes the main cellular mechanism for secreting neurotransmitters. It entails the fusion of a secretory vesicle with plasma membrane, thus promoting the release of its soluble content. Among the cell models that have provided insight into molecular machinery underlying the succesive steps of exocytosis, adrenal chromaffin cells have taken a prominent place. Exocytosis gave support to the classical quantal theory, which maintains that neurotransmitters are released as discrete packages from the nerve terminals towards the postsynaptic cell. We present here a brief review of the estate of our knowlegments about the secretory vesicle traffic towards the cell membrane and how exocytosis takes place through the so called SNARE hypothesis. We also review the novel mechanisms implicated in the regulation of the late steps of exocytosis as well as their possible role as target for drug therapy

Allergy to local anaesthetics in dentistry. Myth or reality?

BACKGROUND

Local anesthetics (LA) are frequently used in dentistry. Although these drugs are usually well-tolerated, they can sometimes provoke adverse reactions of various types and severity. The true incidence of LA allergic reactions is unknown. The objectives of this study were (i) to evaluate the incidence of immediate adverse events in subjects requiring local anesthetic injection in order to receive dental treatment; (ii) to assess the incidence of anaphylactic allergic reactions among those recorded as adverse events and (iii) to analyze the relationship between the atopic antecedents of these patients and documented allergic reactions.

MATERIALS AND METHODS

A prospective, open-label, non-comparative study including 5,018 subjects who received LA during dental treatment, despite their age, was carried out in 7 private or public odontological centers. All the possible reactions that could appear during the first hour of anesthetic administration were assessed.

RESULTS

Twenty-five adverse reactions were diagnosed, representing 0.5 % of the study population. None of these reactions was due to an allergic cause. Most (22/25) were mild, quickly reversible psychogenic or vasovagal reactions. One case was related to defects in the anesthetic technique. In two further cases, allergic etiology was ruled out after skin and dose provocative challenge tests with the anesthetic. In conclusion, allergic reactions to LA are very rare. Most adverse reactions are psychogenic or vasovagal. Physicians and dentists should be aware of these facts in order to minimize the frequent fears and myths concerning the use of LA in the dentist's office.

cAmp modulates exocytotic kinetics and increases quantal size in chromaffin cells

The role of cAMP/cAMP-dependent protein kinase (PKA) on the late phase of exocytosis has been studied by amperometry on Ba(2+)-stimulated single bovine chromaffin cells. Forskolin (FSK) increases the intracellular cAMP levels in a concentration-dependent manner. Forskolin (100 nM) does not increase the number of exocytotic events, although it significantly increases the net granule content of catecholamines (CA), which is accompanied by a slowing of the process of degranulation. These effects are reversible, occur within 15 to 60 s, and are not due to newly synthesized CA. Isoprenaline, pituitary adenylate cyclase-activating polypeptide-38 or dB-cAMP reproduce FSK effects as does cholera toxin. The inhibition of phosphodiesterases with 3-isobutyl-1-methylxanthine mimics and potentiates the effect of FSK and isoprenaline. Rolipram and okadaic acid also produce a drastic increase in net granule content of CA, whereas H-89 attenuates the FSK response. These data indicate that cyclic AMP/PKA might favor the granule aggregation before its fusion with cell membrane and slow the late step of the exocytotic process.

Detection and significance of inapparent infection in Chagas disease in western Venezuela

Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people living in close proximity, and under the same conditions of risk, to patients with acute Chagas disease. Similar infections were also detected in sera samples of people from 25 villages of western Venezuela where Chagas disease is endemic. Seropositivity in all the 1,251 studied samples was established by use of 3 serological methods (direct agglutination test, indirect immunofluorescence antibody test, and enzyme-linked immunosorbent assay). Each seropositive sample was tested for detection of anti-T. cruzi-specific immunoglobulin (Ig) M and IgG levels and specific T. cruzi infection by molecular methodology (polymerase chain reaction assay). The combined analysis of the serologic (IgM and IgG levels), molecular (specific T. cruzi DNA), and statistical findings demonstrated the existence of a different stage of T. cruzi infection in asymptomatic patients, which is suggested to be recognized as inapparent infection. Its definition, significance, and comparison with typical Chagas disease phases are presented, and its potential epidemiological importance is discussed.

Morphological and functional characterization of beige mouse adrenomedullary secretory vesicles

We tested whether the giant secretory granules observed in the mast cells of the naturally occurring mutant beige mouse (BM) (C57BL/6N-bg) were also present in the adrenal chromaffin cells. The presence of large chromaffin granules (CG) would be a valuable tool for the study of exocytosis in neuronal tissues. Conversely, the observation of large vesicles within chromaffin cells that are different from CG could indicate that CG are of a different origin than granules of mast cells. Ultrastructural analysis demonstrated the presence of large lysososmal-like vesicles in the BM, and also a discrete increase in the number of CG with diameters larger than 240 nm but not of giant CG. In addition, amperometric measurements of single-event exocytosis, using carbon fiber microelectrodes, showed no differences between the quantal size of secretory events from BM and wildtype or bovine chromaffin cells. Minor but significant differences were found between the kinetics of exocytosis in BM cells andwild-type mouse cells. We conclude that CG, but not the abnormal-sized vesicles found in BM chromaffin cells contribute to the catecholamine secretion and that abnormal secretory granules are not present in adrenergic cell lineage.

Automatic analysis for amperometrical recordings of exocytosis

Amperometry is a widely used technique for monitoring the secretion of catecholamines (CA) by exocytosis. The use of carbon fibre microelectrodes allows the on-line recording of CA released from a single secretory vesicle. Amperometric signals are generated by oxidation of the quantally released CA close to the electrode tip. Each event of exocytosis is called a secretory spike. Here we describe a program written for IGOR (Wavemetrics, Lake Oswego, OR, USA), which may be used to analyze amperometric signals off-line. The procedures allow, (i) digital filtering and analysis of the current noise, spike identification and calculation of spike kinetic parameters; (ii) spike review; (iii) pooling spikes and data to create galleries, tables and histograms of measured parameters which can be exported to a graphic format or files for further analysis.

The epidemiology and control of leishmaniasis in Andean countries

This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia) infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

Nitric oxide modulates a late step of exocytosis

The effects of nitric oxide (NO) on the late phase of exocytosis have been studied, by amperometry, on Ba(2+)-stimulated chromaffin cells. Acute incubation with NO or NO donors (sodium nitroprusside, spermine-NO, S-nitrosoglutathione) produced a drastic slowdown of the granule emptying. Conversely, cell treatment with N(omega)-nitro-l-arginine methyl ester (a NO synthase inhibitor) or with NO scavengers (methylene blue, 2-(4-carboxyphenyl)-4,4,5, 5-tetramethyl-imidazoline-1-oxyl-3-oxide potassium) accelerated the extrusion of catecholamines from chromaffin granules, suggesting the presence of a NO modulatory tone. The incubation with phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine or zaprinast) or with the cell-permeant cGMP analog 8-bromo-cGMP, mimicked the effects of NO, suggesting the involvement of the guanylate cyclase cascade. NO effects were not related to changes in intracellular Ba(2+). NO did not modify the duration of feet. Effects were evident even on pre-fusioned granules, observed under hypertonic conditions, suggesting that the fusion pore is not the target for NO, which probably acts by modifying the affinity of catecholamines for the intragranular matrix. NO could modify the synaptic transmitter efficacy through a novel mechanism, which involves the regulation of the emptying of secretory vesicles.

A new way for the analysis of the exocytosis

Exocytosis is the most common way for cells to secrete substances. This is a wide distributed phenomenon that involves all cell types and all animal species from yeast to human. Catecholamine (CA) release from adrenal chromaffin cells occurs by the exocytosis of secretory vesicles also called chromaffin granules. Individual secretory events can be easily monitored by the use of carbon fibers encased in glass microelectrodes. Catecholamines oxidized at the electrode tip produce a transient electrical current wave called secretory spike. The typical secretory spike consists in a sharp elevation of current followed by a rapid exponential decrease to the basal level. A 35-50% of the spikes showed a pre-spike wave called "foot" which represents the CA release through the fusion pore. The time course of secretory spikes observed is altered by extracellular phenomena's like diffusion. It has been suggested that amperometric spikes can be described by the convolution of a Gaussian with a decreasing exponential. The exponential function is partially governed by the diffusion of the secreted substances towards the electrode. In this article a method to deconvolve both functions is proposed. This mathematical approach allows the observation of the original secretory profile--the Gaussian--without the distortion caused by the diffusional broadening of catecholamines.

Calcium channel subtypes and exocytosis in chromaffin cells: a different view from the intact rat adrenal

In the intact rat adrenal gland perfused with an oxygenated Krebs-bicarbonate solution at 37 degrees C, the electrical field stimulation of splanchnic nerves (100 V, 0.5 ms duration, 10 Hz during 10 s) produced transient catecholamine release peaks that were reproduced in subsequent stimuli, applied at 8-min intervals. Omega-Conotoxin GVIA (0.3 microM) caused only a modest inhibition of the secretory response, suggesting that the N-subtype of voltage-dependent Ca2+ channels are scarcely involved in such a response. Both omega-conotoxin MVIIC (1 microM) and furnidipine (1 microM) halved the secretion, suggesting that the L- and P/Q-types of Ca2+ channels were involved. N-type Ca2+ channels appear to be involved in the maintenance of secretion in response to sustained stimulus since omega-conotoxin GVIA (0.3 microM) reduced the catecholamine output to 28%. When secretion was elicited by acetylcholine (10 microM), furnidipine reduced the catecholamine release by 50% and omega-conotoxin MVIIC by 40%, whereas omega-conotoxin GVIA did not modify the response. The K+-induced secretory responses (23.6 mM K+, 15 s) were reduced 75% by furnidipine and 45% by omega-conotoxin MVIIC, indicating that this type of stimulation preferentially recruited L-type channels. These data show that electrical stimulation recruits Ca2+ channel subtypes different from those recruited by direct depolarization of chromaffin cells.

Myocardial parasite persistence in chronic chagasic patients

The persistence of Trypanosoma cruzi tissue forms was detected in the myocardium of seropositive individuals clinically diagnosed as chronic chagasic patients following endomyocardial biopsies (EMBs) processed by immunohistochemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (polymerase chain reaction [PCR]) techniques. An indirect immunofluorescent technique revealed antigenic deposits in the cardiac tissue in 24 (88.9%) of 27 patients. Persistent T. cruzi amastigotes were detected by PAP staining in the myocardium of 22 (84.6%) of 26 patients. This finding was confirmed with a PCR assay specific for T. cruzi in 21 (91.3%) of 23 biopsy specimens from the same patients. Statistical analysis revealed substantial agreement between PCR and PAP techniques (k = 0.68) and the PCR and any serologic test (k = 0.77). The histopathologic study of EMB specimens from these patients revealed necrosis, inflammatory infiltrates, and fibrosis, and made it possible to detect heart abnormalities not detected by electrocardiogram and/or cineventriculogram. These indications of myocarditis were supported by the detection of T. cruzi amastigotes by the PAP technique or its genome by PCR. They suggest that although the number of parasites is low in patients with chronic Chagas' disease, their potential for heart damage may be comparable with those present during the acute phase. The urgent necessity for testing new drugs with long-term effects on T. cruzi is discussed in the context of the present results.

Acute Chagas' disease in western Venezuela: a clinical, seroparasitologic, and epidemiologic study

A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phase patients in areas of western Venezuela where Chagas' disease is endemic showed 19 symptomatic patterns or groups of symptoms appearing in combination with different frequencies. The symptomatic pattern with the highest frequency was that showing simultaneously fever, myalgia, headache, and Romaña's sign, which was detected in 20% of the acute-phase patients. Asymptomatic individuals and patients with fever as the only sign of the disease made up 15% and 11.9% of the total acute cases, respectively. Statistical correlation analysis revealed that xenodiagnosis and hemoculture were the most reliable and concordant of the five parasitologic methods used; these two methods also showed the highest proportions in detecting any clinical symptomatic pattern in acute-phase patients. A similar high reliability and concordance was obtained with a direct agglutination test, an indirect immunofluorescent antibody test, and an ELISA as serologic tests, which also showed a higher proportion of positive detection of clinical patterns than parasitologic methods (P < 0.001). It is recommended that individuals coming from endemic areas showing mild and/or severe clinical manifestations should be suspected of being in contact or having been in contact with Trypanosoma cruzi, be referred for parasitologic and serologic evaluations to confirm the presumptive clinical diagnosis of acute Chagas' disease, and start specific treatment. The epidemiologic implications of the present findings are discussed and the use of similar methodology to evaluate other areas where Chagas' disease is endemic is suggested.

Photophysical properties and photobiological activity of the furanochromones visnagin and khellin

The larger photobiological activity of visnagin (VI) versus khellin (KH) toward several living organisms, including fungi, viruses, yeasts and bacteria, induced a detailed investigation of the photophysical properties of these naturally occurring furanochromones, using laser-flash-photolysis, photoacoustic calorimetry and fluorescence (steady-state and time-resolved) techniques in solvents with different polarity and content of water, including micelles and vesicles. The results have shown that the magnitude of all the three rate constants out of S1 (radiative, kf; internal conversion, kic and intersystem crossing, kisc) for VI and KH strongly depend on the solvent, namely on its hydrogen bonding ability and polarity. The changes of kf and kisc are due to the solvent-assisted mixing and/or inversion of the two first singlet excited states (1n, pi and 1 pi, pi), while kic increases with a decrease of the S0-S1 energy gap. As a consequence, the quantum yield of triplet formation (phi T) strongly decreases from values of approximately 0.8 in dioxane to < 0.05 in water for both compounds. The magnitude of solvent polarity/hydrogen bonding ability required, at which the state order is inverted and phi T starts to decrease, is greater for VI than for KH and consequently phi T (VI) >> phi T (KH) over a broad range of water content including that appropriate to the environment of the compounds in a living system. These facts account for the larger photobiological activity of VI with respect to KH, regarding both the fungus Fusarium culmorum L. and the wild strain of Escherichia coli, studied by us.

Effects of external osmotic pressure on vesicular secretion from bovine adrenal medullary cells

Secretion of catecholamines from individual vesicles of bovine adrenal medullary cells was studied with amperometry in media of various osmolarities and compared with results obtained in isotonic physiological buffer (315 mosM). Hypotonic solutions caused an increase in the number of amperometric spikes evoked by brief exposure to 5 mM Ba2+. Under moderate hypertonic conditions (630 mosM), individual vesicular events were decreased in frequency, and lower amounts were secreted per event. Furthermore, the events were temporally broadened relative to those observed during release in isotonic conditions. At 970 mosM, exposure to 5 mM Ba2+ evoked even smaller secretory events that resemble the prespike feature that has been attributed to the initial opening of the fusion pore. The lack of large spikes is not due to failure of Ba2+ entry because fura-2 fluorescence reveals an increase in intracellular divalent ions. After exposure to Ba2+ in hypertonic solution, spikes could be induced with isotonic solution transiently directed onto the cell, but this process was not accompanied by a change in the concentration of intracellular divalent ions. Thus, this procedure provides an unique opportunity to temporally separate exocytotic secretion from entry of divalent ions.

Interaction between G protein-operated receptors eliciting secretion in rat adrenals. A possible role of protein kinase C

Catecholamine release induced by angiotensin II, histamine, bradykinin and methacholine from the rat adrenal gland perfused in vitro was studied under conditions in which the activity of protein kinase C (PKC) was modified. Perfusion of glands with 10 nM bradykinin abolished, in a reversible way, the secretion induced by short pulses of angiotensin II, histamine and methacholine but did not modify the release evoked by 23.6 mM KCl (high K+). Perfusion with histamine or methacholine (30 microM) inhibited the secretion induced by the other agents by 30-50%, whereas incubation with angiotensin II (100 nM) caused little or no reduction in the release evoked by the other agents. The treatment of glands with 1 nM of the PKC activator phorbol 12,13-dibutyrate (PDBu) suppressed the responses induced by angiotensin II, histamine and methacholine, did not affect those evoked by bradykinin, and potentiated the secretion evoked by high K+. The adenylate cyclase stimulator forskolin (1 microM) did not affect the basal secretion but strongly potentiated the release evoked by all secretagogues used, suggesting a role for protein kinase A (PKA) downstream of the receptor. The PKC inhibitor Ro-31-8220 partially reversed the inhibitory effect of bradykinin. Our results suggest that angiotensin II, histamine and muscarinic receptors share some common transduction mechanism that is regulated by PKC. PKC activity was enhanced by these agents PDBu >> bradykinin = histamine > methacholine = angiotensin II. Bradykinin receptor transduction does not appear to be regulated by PKC.

Exocytotic release from individual granules exhibits similar properties at mast and chromaffin cells

The effects of temperature on granular secretion were studied in individual bovine adrenal chromaffin and rat peritoneal mast cells. It was found that more molecules are released from individual granules at physiological temperature than at room temperature, where such experiments are normally performed. In mast cells, there is also a dramatic decrease in the time required for exocytosis to be complete at 37 degrees C compared to room temperature. In the presence of some cations, the amount released from individual granules at room temperature from both types of cells could be altered. The amount of secretion decreased with the divalent cation zinc but increased with the monovalent cation cesium. These experiments used two electrochemical techniques: cyclic voltammetry and amperometry. With amperometry, the concentration gradient created by the electrode near the cell further increased the amount of release. Similar responses to changes in the extracellular environment in chromaffin and mast cells suggest that the mechanism of extrusion of the granule contents is similar in both cell types.

Comparison of cytosolic Ca2+ and exocytosis responses from single rat and bovine chromaffin cells

The relationship between cytosolic Ca2+ and catecholamine secretion during stimulus-secretion coupling has been examined at individual chromaffin cells isolated from the cow and rat. Vesicular catecholamine exocytosis was determined via amperometric measurements with carbon fibre microelectrodes and fura-2 was used for simultaneous fluorescent monitoring of cytosolic Ca2+ at the same cell. Individual secretory vesicles in cells from the two species were found to release similar amounts of catecholamine. In addition, the time courses for secretion from individual vesicles was similar with rat and bovine chromaffin cells. The total quantity of catecholamine released and the change in cytosolic Ca2+ were also similar in response to exposure to K+ (60 mM), 1,1-dimethyl-4-phenylpiperazinium (50 microM), and histamine (50 microM), although both responses were more prolonged following 1,1-dimethyl-4-phenylpiperazinium and histamine at bovine cells. Agents that mobilize intracellular Ca(2+)-stores such as methacholine, caffeine and bradykinin resulted in different cytosolic Ca2+ and exocytosis responses at the rat and bovine chromaffin cells. Results indicate a heightened Ca(2+)-store activity or a more filled state in chromaffin cells from the rat. The results of this study clearly show that single-cell techniques can be used to characterize stimulus-secretion coupling. The requirement for lower numbers of cells with these techniques means that chromaffin cells from rodents can be routinely employed. This can be advantageous to minimize biological variability which occurs with organs obtained from slaughter houses and enables the investigation of genetically-altered animals.

Blocking effects of otilonium on Ca2+ channels and secretion in rat chromaffin cells

We describe here the effects of otilonium bromide (an anticholinergic agent widely used as an intestinal spasmolytic) on whole-cell currents through Ca2+ channels (IBa) and catecholamine secretion in rat adrenal glands and isolated rat chromaffin cells. Otilonium blocked the peak IBa current in voltage-clamped chromaffin cells in a concentration-dependent manner; the IC50 to block IBa was 4.7 microM. Blockade was not accompanied by a significant shift in the I-V relationship for IBa, suggesting that such blockade was not affecting a specific subtype of Ca2+ channel. When given intracellularly through the patch pipette, otilonium (10 microM) did not block IBa. However, its external application to the same cell (10 microM) reversibly reduced IBa by 70%. Otilonium caused a concentration-dependent blockade of catecholamine release from perfused rat adrenal glands intermittently stimulated with methacholine, high K+ or histamine. The IC50 to block secretion after a 5 min incubation with otilonium was 0.02, 0.7 and 3 microM, respectively, for methacholine, K+ and histamine. The blocking effects of otilonium were fully reversible at concentrations below 10 microM. The Ca2+ channel agonist Bay K 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyr idine-5- carboxylate) partially antagonized the effects of otilonium on K(+)-evoked secretion and accelerated the time course of recovery from inhibition. The results are compatible with the idea that otilonium blocks Ca2+ entry into chromaffin cells by blocking voltage-dependent Ca2+ channels. This would lead to a limitation in the rise in cytosolic Ca2+ at secretory sites and to inhibition of catecholamine release in response to stimulation of chromaffin cells.

Otilonium: a potent blocker of neuronal nicotinic ACh receptors in bovine chromaffin cells

1. Otilonium, a clinically useful spasmolytic, behaves as a potent blocker of neuronal nicotinic acetylcholine receptors (AChR) as well as a mild wide-spectrum Ca2+ channel blocker in bovine adrenal chromaffin cells. 2. 45Ca2+ uptake into chromaffin cells stimulated with high K+ (70 mM, 1 min) was blocked by otilonium with an IC50 of 7.6 microM. The drug inhibited the 45Ca2+ uptake stimulated by the nicotinic AChR agonist, dimethylphenylpiperazinium (DMPP) with a 79 fold higher potency (IC50 = 0.096 microM). 3. Whole-cell Ba2+ currents (IBa) through Ca2+ channels of voltage-clamped chromaffin cells were blocked by otilonium with an IC50 of 6.4 microM, very close to that of K(+)-evoked 45Ca2+ uptake. Blockade developed in 10-20 s, almost as a single step and was rapidly and almost fully reversible. 4. Whole-cell nicotinic AChR-mediated currents (250 ms pulses of 100 microM DMPP) applied at 30 s intervals were blocked by otilonium in a concentration-dependent manner, showing an IC50 of 0.36 microM. Blockade was induced in a step-wise manner. Wash out of otilonium allowed a slow recovery of the current, also in discrete steps. 5. In experiments with recordings in the same cells of whole-cell IDMPP, Na+ currents (INa) and Ca2+ currents (ICa), 1 microM otilonium blocked 87% IDMPP, 7% INa and 13% ICa. 6. Otilonium inhibited the K(+)-evoked catecholamine secretory response of superfused bovine chromaffin cells with an IC50 of 10 microM, very close to the IC50 for blockade of K(+)-induced 45Ca2+ uptake and IBa. 7. Otilonium inhibited the secretory responses induced by 10 s pulses of 50 microM DMPP with an IC50 of 7.4 nM. Hexamethonium blocked the DMPP-evoked responses with an IC50 of 29.8 microM, 4,000 fold higher than that of otilonium. 8. In conclusion, otilonium is a potent blocker of nicotinic AChR-mediated responses. The drugs also blocked various subtypes of neuronal voltage-dependent Ca2+ channels at a considerably lower potency. Na+ channels were unaffected by otilonium. This extraordinary potency of otilonium in blocking nicotinic AChR, unrecognised until now, might account in part for its well known spasmolytic effects.

Temporally resolved, independent stages of individual exocytotic secretion events

The stages of the complex events involved in exocytotic secretion after vesicle-cell membrane fusion have been examined at the level of individual vesicles. Catecholamine flux from single bovine adrenal medullary cells was measured with carbon-fiber microelectrodes firmly touching the cell surface. The data reveal that secretion during exocytotic events has three distinct stages: a small increase in catecholamine flux, a rapid, but not instantaneous, rise to a maximum, followed by an exponential decrease in the flux. These stages are interpreted in the following ways. The initial stage corresponds to catecholamine secretion through a fusion pore. The rate of pore expansion appears to control the rise time of the flux to its maximum value. The final exponential stage is consistent with chemical dissociation of the intravesicular matrix or gel.

Multiple calcium channel subtypes in isolated rat chromaffin cells

By using the whole-cell configuration of the patch-clamp technique we have investigated the pharmacological properties of Ca2+ channels in short-term cultured rat chromaffin cells. In cells held at a membrane potential of --80 mV, using 10 mM Ba2+ as the charge carrier, only high-voltage-activated (HVA) Ca2+ channels were found. Ba2+ currents (IBa) showed variable sensitivity to dihydropyridine (DHP) Ca2+ channel agonists and antagonists. Furnidipine, a novel DHP antagonist, reversibly blocked the current amplitude by 22% and 48%, at 1 microM and 10 microM respectively, during short (15-50 ms) depolarizing pulses to 0 mV. The L-type Ca2+ channel agonist Bay K 8644 (1 microM) caused a variable potentiation of HVA currents that could be better appreciated at low rather than at high depolarizing steps. Increase of IBa was accompanied by a 20-mV shift in the activation curves for Ca2+ channels towards more hyperpolarizing potentials. Application of the conus toxin omega-conotoxin GVIA (GVIA; 1 microM) blocked 31% of IBa; blockade was irreversible upon removal of the toxin from the extracellular medium. omega-Agatoxin IVA (IVA; 100 nM) produced a 15% blockade of IBa. omega-Conotoxin MVIIC (MVIIC; 5 microM) produced a 36% blockade of IBa; such blockade seems to be related to both GVIA-sensitive (N-type) and GVIA-resistant Ca2+ channels. The sequential addition of supramaximal concentrations of furnidipine (10 microM), GVIA (1 microM), IVA (100 nM) and MVIIC (3 microM) produced partial inhibition of IBa, which were additive. Our data suggest that the whole cell IBa in rat chromaffin cells exhibits at least four components.(ABSTRACT TRUNCATED AT 250 WORDS)

A population-based clinical trial with the SPf66 synthetic Plasmodium falciparum malaria vaccine in Venezuela

A phase III malaria vaccine trial in 13 villages in an endemic area, South Venezuela, compared incidence rates of Plasmodium falciparum and Plasmodium vivax infections in 1422 vaccinated and 938 nonvaccinated subjects over 18 months. The SPf66 vaccine was given in three doses, on days 0, 20, and 112. Vaccination was complete in 976 subjects (68.7%). Minor side effects requiring no treatment were reported by 123 (12.6%), with an apparent increase in frequency from the first to the third vaccine dose. No autoimmune evidence was observed in a sample of subjects. Antibodies against SPf66 were present at low titers in 24.7% of tested subjects before vaccination, increasing to 53.6% after the second dose and to 73.6% after the third dose; 26.4% of subjects initially seronegative never seroconverted. The SPf66 malaria vaccine showed a protective efficacy of 55% (95% confidence interval, 21%-75%) against P. falciparum and of 41% (19%-57%) against P. vivax malaria.

Localized L-type calcium channels control exocytosis in cat chromaffin cells

Depolarizing 1-s pulses to 0 mV from a holding potential of -70 mV, induced whole-cell currents through Ca2+ channels (ICa) in patch-clamped cat adrenal medulla chromaffin cells. The dihydropyridine (DHP) furnidipine (3 microM) reduced the peak current by 47% and the late current by 80%. omega-Conotoxin GVIA (CgTx, 1 microM) reduced the peak ICa by 42% and the late ICa by 55%. Pulses (10 s duration) with 70 mM K+/2.5 mM Ca2+ solution (70 K+/2.5 Ca2+), applied to single fura-2-loaded cat chromaffin cells increased the cytosolic Ca2+ concentration ([Ca2+]i) from 0.1 to 2.21 microM; this increase was reduced by 43.7% by furnidipine and by 42.5% by CgTx. In the perfused cat adrenal gland, secretion evoked by 10-s pulses of 70 K+/2.5 Ca2+ was reduced by 25% by CgTx and by 96% by furnidipine. Similar results were obtained when secretion from superfused isolated cat adrenal chromaffin cells was studied and when using a tenfold lower [Ca2+]o. The results are compatible with the existence of DHP-sensitive (L-type) as well as CgTx-sensitive (N-type) voltage-dependent Ca2+ channels in cat chromaffin cells. It seems, however, that though extracellular Ca2+ entry through both channel types leads to similar increments of averaged [Ca2+]i, the control of catecholamine release is dominated only by Ca2+ entering through L-type Ca2+ channels. This supports the idea of a preferential segregation of L-type Ca2+ channels to localized "hot spots" in the plasmalemma of chromaffin cells where exocytosis occurs.

Histamine H1 receptor activation mediates the preferential release of adrenaline in the rat adrenal gland

Histamine elicited the release of catecholamines from "in vitro" perfused rat adrenals with an EC50 of 3 microM. This concentration was in the same range as those which caused a fall in the arterial blood pressure when infused intravenously in anaesthetized rats. Histamine stimulation was potently blocked by dexclorfeniramine (IC50 = 300 pM), but unaffected by ranitidine, suggesting the involvement of H1 receptors. Histamine release preferentially adrenaline. Mast cells were not detected within adrenal medulla by histochemical techniques. Compound 48/80 did not trigger catecholamine release. Catecholamine secretion evoked by splanchnic nerves stimulation was not modified by a combination of H1 and H2 antagonists. In conclusion, the histamine that elicited adrenaline release from rat adrenals comes from blood circulation not from local mast cells or splanchnic nerves. These effects are mediated through the activation of H1 receptors.

Ionic mechanisms involved in the secretory effects of histamine in the rat adrenal medulla

Histamine activation of H1 receptors elicited the release of adrenaline from in vitro perfused rat adrenal with an EC50 of 3 microM. Neither Na+ deprivation nor complete membrane depolarization abolished the histamine-mediated secretory response but it was partially dependent on extracellular Ca2+. Nitrendipine and BAY-K-8644 affected the release induced by histamine concentrations at over 3 microM. Delayed application of histamine pulses, after external Ca2+ removal, led to a decline in to a plateau at 50% of the initial release. Pretreatment with ionomycin abolished this Ca2+ deprivation-resistant component. These data suggest that secretion evoked by low concentrations of histamine occurs by mobilization of Ca2+ from internal stores whereas higher concentrations use Ca2+ from both intracellular and extracellular sources.