How can policymakers incorporate uncertainty (as modelled through foresight) into policy evaluation?

Background

Using a robust policy evaluation framework is critical to inform policymakers about the relevance of a policy in a structured way, clarifying its implications and providing arguments and criteria to compare competing options and decide which policy should be prioritised. In the current context of complex societal, environmental and public health challenges, decision-makers demand tools that allow a comparative assessment of the effectiveness of multisectoral policies and their comparison under different scenarios.

Methods

This presentation will detail a socio-technical “desirability-doability” framework (2xD). In 2xD, an additive value model is constructed to measure the desirability of public policies, and their doability is appraised under two contrasted scenarios. For these purposes, the MACBETH approach is used in developing the three group modelling phases of 2xD: (I) Structuring facilitated workshops, (II) Evaluation decision conference, and (III) Desirability-doability decision conference. Tailor-made interactive protocols or questioning procedures are used to elicit group judgements, based on which objective-specific value scores are assigned to the policies, and the objectives are weighted (in II). Finally, we elicit doability scores for the policies under each scenario (in III).

Results

We present how the 2xD framework was applied in Lisbon's urban health policymaking setting and discuss case insights regarding the role of scenario analysis in the appraisal and selection of policies.

Conclusions

The 2xD framework advances knowledge on how to assist policymakers in evaluating and selecting policies and contributes to the literature on overall policy formulation and evaluation. Specifically, the framework enabled a group of policymakers to balance (multicriteria) desirability versus doability of policies under the light of two contrasting scenarios, therefore incorporating uncertainty in their decision-making process.

Sustained hypoxia in mice increases parasympathetic but not sympathetic tone

The autonomic profile of mice submitted to sustained hypoxia (SH) was not yet fully evaluated. Herein, we characterized the cardiovascular and autonomic profile of conscious freely moving mice submitted to SH using two sequential experimental protocols to evaluate the parasympathetic and sympathetic tone to the heart and the sympathetic tone to the vascular resistance. In the first protocol the sequence of antagonists was methyl-atropine followed by propranolol and then by prazosin, while in the second protocol the sequence was propranolol followed by methyl-atropine and then by prazosin. In SH the baseline heart rate was significantly lower than in control mice and the antagonism of the parasympathetic and sympathetic tone to the heart in both experimental protocols indicated an increased parasympathetic tone in SH mice and no changes in the sympathetic tone. Antagonism of the sympathetic tone to the vascular resistance with prazosin produced similar changes in arterial pressure in control and SH mice. Altogether these findings support the concept that mice submitted to SH present a significant increase in the parasympathetic but not in the sympathetic tone, which may explain why the baseline arterial pressure was not increased in SH mice.

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Autonomic profile of awake mice submitted to sustained hypoxia (SH) was evaluated by sequential pharmacological antagonists.

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Baseline heart rate in SH mice was lower and the tachycardic response to methyl-atropine was greater than in control mice.

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Fall in mean arterial pressure in response to prazosin was similar in control and SH mice.

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Parasympathetic tone to the heart of mice submitted to SH is increased while the overall sympathetic tone is not.

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These findings contribute to explain why mice, different of rats, are not hypertensive in response to SH.

Increased cholinergic activity under conditions of low estrogen leads to adverse cardiac remodeling

Cholinesterase inhibitors are used in postmenopausal women for the treatment of neurodegenerative diseases. Despite their widespread use in the clinical practice, little is known about the impact of augmented cholinergic signaling on cardiac function under reduced estrogen conditions. To address this gap, we subjected a genetically engineered murine model of systemic vesicular acetylcholine transporter overexpression (Chat-ChR2) to ovariectomy and evaluated cardiac parameters. Left-ventricular function was similar between Chat-ChR2 and wild-type (WT) mice. Following ovariectomy, WT mice showed signs of cardiac hypertrophy. Conversely, ovariectomized (OVX) Chat-ChR2 mice evolved to cardiac dilation and failure. Transcript levels for cardiac stress markers atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) were similarly upregulated in WT/OVX and Chat-ChR2/OVX mice. 17β-Estradiol (E2) treatment normalized cardiac parameters in Chat-ChR2/OVX to the Chat-ChR2/SHAM levels, providing a link between E2 status and the aggravated cardiac response in this model. To investigate the cellular basis underlying the cardiac alterations, ventricular myocytes were isolated and their cellular area and contractility were assessed. Myocytes from WT/OVX mice were wider than WT/SHAM, an indicative of concentric hypertrophy, but their fractional shortening was similar. Conversely, Chat-ChR2/OVX myocytes were elongated and presented contractile dysfunction. E2 treatment again prevented the structural and functional changes in Chat-ChR2/OVX myocytes. We conclude that hypercholinergic mice under reduced estrogen conditions do not develop concentric hypertrophy, a critical compensatory adaptation, evolving toward cardiac dilation and failure. This study emphasizes the importance of understanding the consequences of cholinesterase inhibition, used clinically to treat dementia, for cardiac function in postmenopausal women.

Changes in the autonomic and respiratory patterns in mice submitted to short-term sustained hypoxia

NEW FINDINGS

What is the central question of this study? Do mice submitted to sustained hypoxia present autonomic and respiratory changes similarly to rats? What is the main finding and its importance? Arterial pressure in the normal range, reduced baseline heart rate and tachypnoea were observed in behaving sustained hypoxia mice. Recordings in the in situ preparation of mice submitted to sustained hypoxia show an increase in cervical vagus nerve activity and a simultaneous reduction in thoracic sympathetic nerve activity correlated with changes in the respiratory cycle. Therefore, mice are an important model for studies on the modulation of sympathetic activity to the cardiovascular system and the vagus innervation of the upper airways due to changes in the respiratory network induced by sustained hypoxia.

ABSTRACT

Short-term sustained hypoxia (SH) in rats induces sympathetic overactivity and hypertension due to changes in sympathetic-respiratory coupling. However, there are no consistent data about the effect of SH on mice due to the different protocols of hypoxia and difficulties associated with the handling of these rodents under different experimental conditions. In situ recordings of autonomic and respiratory nerves in SH mice have not been performed yet. Herein, we evaluated the effects of SH ( F i O 2  = 0.1 for 24 h) on baseline mean arterial pressure (MAP), heart rate (HR), respiratory frequency (f_R ) and responses to chemoreflex activation in behaving SH mice. A characterization of changes in cervical vagus (cVN), thoracic sympathetic (tSN), phrenic (PN) and abdominal (AbN) nerves in SH mice using the in situ working heart-brainstem preparation was also performed. SH mice presented normal MAP, significant reduction in baseline HR, increase in baseline f_R , as well as increase in the magnitude of bradycardic response to chemoreflex activation. In in situ preparations, SH mice presented a reduction in PN discharge frequency, and increases in the time of expiration and incidence of late-expiratory bursts in AbN activity. Nerve recordings also indicated a significant increase in cVN activity and a significant reduction in tSN activity during expiration in SH mice. These findings make SH mice an important experimental model for better understanding how changes in the respiratory network may impact on the modulation of vagal control to the upper airways, as well as in the sympathetic activity to the cardiovascular system.

Cardiovascular and Autonomic Dysfunction in Murine Ligature-Induced Periodontitis

The present study examined the hemodynamics [arterial pressure (AP), AP variability (APV), heart rate (HR), and heart rate variability (HRV)], cardiac function (echocardiographycally), and myocardial inflammation in Balb/c mice submitted to Periodontitis, through the ligation of the left first molar, or Sham surgical procedure. The first protocol indicated that the AP was similar (136 ± 2 vs. 132 ± 3 mmHg in Sham), while the HR was higher in mice with Periodontitis (475 ± 20 vs. 412 ± 18 bpm in Sham), compared to their Sham counterparts. The APV was higher in mice with Periodontitis when evaluated in the time domain (4.5 ± 0.3 vs. 3.4 ± 0.2 mmHg in Sham), frequency domain (power of the LF band of systolic AP), or through symbolic analysis (patterns 0V + 1V), indicating a sympathetic overactivity. The HRV was similar in the mice with Periodontitis, as compared to their Sham counterparts. In the second protocol, the mice with Periodontitis showed decreased cardiac output (10 ± 0.8 vs. 15 ± 1.4 mL/min in Sham) and ejection fraction (37 ± 3 vs. 47 ± 2% in Sham) associated with increased myocardial cytokines (Interleukin-17, Interleukin-6, and Interleukin-4). This study shows that experimental Periodontitis caused cardiac dysfunction, increased heart cytokines, and sympathetic overactivity, in line with epidemiological studies indicating an increased risk of cardiovascular events in clinical Periodontitis.

Elastase-2, a Tissue Alternative Pathway for Angiotensin II Generation, Plays a Role in Circulatory Sympathovagal Balance in Mice

In vitro and ex vivo experiments indicate that elastase-2 (ELA-2), a chymotrypsin-serine protease elastase family member 2A, is an alternative pathway for angiotensin II (Ang II) generation. However, the role played by ELA-2 in vivo is unclear. We examined ELA-2 knockout (ELA-2KO) mice compared to wild-type (WT) mice and determined whether ELA-2 played a role in hemodynamics [arterial pressure (AP) and heart rate (HR)], cardiocirculatory sympathovagal balance and baroreflex sensitivity. The variability of systolic arterial pressure (SAP) and pulse interval (PI) for evaluating autonomic modulation was examined for time and frequency domains (spectral analysis), whereas a symbolic analysis was also used to evaluate PI variability. In addition, baroreflex sensitivity was examined using the sequence method. Cardiac function was evaluated echocardiographically under anesthesia. The AP was normal whereas the HR was reduced in ELA-2KO mice (425 ± 17 vs. 512 ± 13 bpm from WT). SAP variability and baroreflex sensitivity were similar in both strains. The LF power from the PI spectrum (33.6 ± 5 vs. 51.8 ± 4.8 nu from WT) and the LF/HF ratio (0.60 ± 0.1 vs. 1.45 ± 0.3 from WT) were reduced, whereas the HF power was increased (66.4 ± 5 vs. 48.2 ± 4.8 nu from WT) in ELA-2KO mice, indicating a shift toward parasympathetic modulation of HR. Echocardiographic examination showed normal fractional shortening and an ejection fraction in ELA-2KO mice; however, the cardiac output, stroke volume, and ventricular size were reduced. These findings provide the first evidence that ELA-2 acts on the sympathovagal balance of the heart, as expressed by the reduced sympathetic modulation of HR in ELA-2KO mice.

Abstract P237: Is Ischemia/Reperfusion an Efficient Method for Producing Heart Failure in Rats?

Myocardium infarction (MI) elicited by coronary artery ligation (CAL) is commonly used to induce chronic heart failure (HF) in rats. However, CAL shows high mortality rates. Given that ischemia-reperfusion (IR) may cause the development of HF, this approach may be useful for obtaining a model of HF with low mortality rates. Therefore, it was compared the model of CAL vs. IR in rats, evaluating the mortality and cardiac morphological and functional aspects. The IR consisted of 30 minutes of cardiac ischemia. Wistar rats were assigned into three groups: CAL: n=18; IR: n=7; SHAM (fictitious IR): n=7. After four weeks of CAL, the subjects were evaluated by echocardiography and ventriculography as well. The statistical analysis consisted of ANOVA combined with Tukey’s posthoc test (p<0.05). There were no deaths in the IR and SHAM groups, whereas in the CAL group the mortality rate was 33.33% (6 out of 18). In the CAL group echocardiography showed increased left ventricular (LV) cavity during systole (8.3 ± 1mm) and diastole (10.5 ± 1mm); decreased LV free wall during systole (1.4 ± 0.5 mm); increased left atrium/aorta (2.3 ± 0.4) ratio. These changes were not significant in IR (4.8 ± 0.5mm, 7.6 ± 0.6mm, 2.6 ± 0.3 mm, 1.6 ± 0.2) and SHAM (4.6 ± 0.6 mm, 7.7 ± 0.8mm, 2.8 ± 0.4mm, 1.5 ± 0.2) groups. There was also the reduction in the ejection fraction in the CAL group (41 ± 12 %) when compared with IR (65 ± 9%) and SHAM (69 ± 7%) groups. The tissue Doppler analysis from the lateral mitral annulus showed reduction in E′ in CAL (-29 ± 8 mm/s) and IR (-31± 9 mm/s) groups when compared with the SHAM (-48 ± 11 mm/s) group. The ventriculography in the CAL group showed smaller maximum dP/dt (6519 ± 1062) and greater end-diastolic pressure (33 ± 8 mmHg) when compared with IR (8716 ± 756 mmHg/s; 9 ± 9 mmHg) and SHAM (7989 ± 1230 mmHg/s; 9 ± 7 mmHg) groups. The CAL group presented transmural infarct size of 40% of the left ventricular wall, measured under histopathological examination. In conclusion, IR for 30 minutes caused only small changes in LV diastolic function, assessed by tissue Doppler; however, the IR was not effective for promoting HF, as observed with CAL. Thus, it is possible that prolonged IR is necessary for promoting significant HF in rats.

Heart rate complexity in sinoaortic-denervated mice

NEW FINDINGS

What is the central question of this study? New measurements for cardiovascular complexity, such as detrended fluctuation analysis (DFA) and multiscale entropy (MSE), have been shown to predict cardiovascular outcomes. Given that cardiovascular diseases are accompanied by autonomic imbalance and decreased baroreflex sensitivity, the central question is: do baroreceptors contribute to cardiovascular complexity? What is the main finding and its importance? Sinoaortic denervation altered both DFA scaling exponents and MSE, indicating that both short- and long-term mechanisms of complexity are altered in sinoaortic denervated mice, resulting in a loss of physiological complexity. These results suggest that the baroreflex is a key element in the complex structures involved in heart rate variability regulation. Recently, heart rate (HR) oscillations have been recognized as complex behaviours derived from non-linear processes. Physiological complexity theory is based on the idea that healthy systems present high complexity, i.e. non-linear, fractal variability at multiple scales, with long-range correlations. The loss of complexity in heart rate variability (HRV) has been shown to predict adverse cardiovascular outcomes. Based on the idea that most cardiovascular diseases are accompanied by autonomic imbalance and a decrease in baroreflex sensitivity, we hypothesize that the baroreflex plays an important role in complex cardiovascular behaviour. Mice that had been subjected to sinoaortic denervation (SAD) were implanted with catheters in the femoral artery and jugular vein 5 days prior to the experiment. After recording the baseline arterial pressure (AP), pulse interval time series were generated from the intervals between consecutive values of diastolic pressure. The complexity of the HRV was determined using detrended fluctuation analysis and multiscale entropy. The detrended fluctuation analysis α1 scaling exponent (a short-term index) was remarkably decreased in the SAD mice (0.79 ± 0.06 versus 1.13 ± 0.04 for the control mice), whereas SAD slightly increased the α2 scaling exponent (a long-term index; 1.12 ± 0.03 versus 1.04 ± 0.02 for control mice). In the SAD mice, the total multiscale entropy was decreased (13.2 ± 1.3) compared with the control mice (18.9 ± 1.4). In conclusion, fractal and regularity structures of HRV are altered in SAD mice, affecting both short- and long-term mechanisms of complexity, suggesting that the baroreceptors play a considerable role in the complex structure of HRV.

Analysis of accessibility for buildings of a graduation school--an experiment in ergonomics training curriculum

This article presents a description of a study experience developed in the Discipline of Supervised Internship of the Industrial Design Course of the Federal University of Paraíba. The study is based on focused on ergonomics analysis and accessibility as an object of study, access into and out of buildings of classrooms and laboratories of the same institution. Among the buildings selected, which encompass where the course is established, is a contemporary building and a renovated building of historical and artistic values for current use. The study is characterized by a description of the objects of study, analysis of the reference literature and recommendations for adjustments in the event of any inconsistency with the accessibility standards. The experience of this supervised training provided an opportunity to perform design activities to a group of students in applied ergonomics, as well as enabling contact with professional practice, adding the contact with the appropriate guidelines governing intervention in historic heritage buildings.

Performance of the Striped Mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae) under Variable Conditions of Temperature and Mating

Mealybugs have strong associations with their host plants due to their limitations for dispersal. Thus, environmental conditions and host quality may impact the biological traits of mealybugs. To the best of our knowledge, we are the first to report on the biology of a Brazilian population of the striped mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae), which has recently been reported to infest cotton in Brazil. We evaluated the development and reproductive performance of F. virgata reared under different temperatures (25, 27, and 28°C) and mating status. The type of reproduction was also studied with insects reared on a factitious host and on cotton plants. Shorter development was obtained at 28°C as follows: nymphs generating males and females exhibited three and four instars with a mean duration of 19.1 and 20.5 days, respectively. The nymphal viability ranged from 77 to 96%, and was highest at 25°C. Females reared at 28°C initiated reproduction earlier (16.4 days), but the reproductive period was similar in all temperatures (∼16.2 days). Females produced more nymphs at 27 and 28°C (440 and 292 neonates) than at 25°C (277 neonates), although they lived longer at 25°C (63 days). Ferrisia virgata females exhibited only sexual reproduction. Thus, only mated females produced offspring, whereas unmated females died without reproducing. Therefore, the studied population of F. virgata exhibited only sexual reproduction with high survival and offspring production when fed cotton. Furthermore, pumpkin is a feasible host for mass rearing this mealybug species in the laboratory, an opening avenue for future studies.

Hemodynamic and ventilatory response to different levels of hypoxia and hypercapnia in carotid body-denervated rats

OBJECTIVE

Chemoreceptors play an important role in the autonomic modulation of circulatory and ventilatory responses to changes in arterial O(2) and/or CO(2). However, studies evaluating hemodynamic responses to hypoxia and hypercapnia in rats have shown inconsistent results. Our aim was to evaluate hemodynamic and respiratory responses to different levels of hypoxia and hypercapnia in conscious intact or carotid body-denervated rats.

METHODS

Male Wistar rats were submitted to bilateral ligature of carotid body arteries (or sham-operation) and received catheters into the left femoral artery and vein. After two days, each animal was placed into a plethysmographic chamber and, after baseline measurements of respiratory parameters and arterial pressure, each animal was subjected to three levels of hypoxia (15, 10 and 6% O(2)) and hypercapnia (10% CO(2)).

RESULTS

The results indicated that 15% O(2) decreased the mean arterial pressure and increased the heart rate (HR) in both intact (n = 8) and carotid body-denervated (n = 7) rats. In contrast, 10% O(2) did not change the mean arterial pressure but still increased the HR in intact rats, and it decreased the mean arterial pressure and increased the heart rate in carotid body-denervated rats. Furthermore, 6% O(2) increased the mean arterial pressure and decreased the HR in intact rats, but it decreased the mean arterial pressure and did not change the HR in carotid body-denervated rats. The 3 levels of hypoxia increased pulmonary ventilation in both groups, with attenuated responses in carotid body-denervated rats. Hypercapnia with 10% CO(2) increased the mean arterial pressure and decreased HR similarly in both groups. Hypercapnia also increased pulmonary ventilation in both groups to the same extent.

CONCLUSION

This study demonstrates that the hemodynamic and ventilatory responses varied according to the level of hypoxia. Nevertheless, the hemodynamic and ventilatory responses to hypercapnia did not depend on the activation of the peripheral carotid chemoreceptors.

Changes in autonomic control of the cardiovascular system in the Wistar audiogenic rat (WAR) strain

We evaluated autonomic cardiovascular modulation and baroreflex control of heart rate (HR) in a particular epileptic rat strain, Wistar audiogenic rats (WARs). We studied spontaneous baroreflex sensitivity as well as reflex changes in HR evoked by phenylephrine/nitroprusside-induced changes in arterial pressure (AP). Atropine and propranolol were used to measure cardiac autonomic tone. AP and pulse interval (PI) variability analysis were performed in the time and frequency domains (FFT spectral analysis) to evaluate cardiovascular sympatovagal modulation in WARs. AP and HR were higher in WARs (109±2 mm Hg and 366±9 bpm) than in Wistar control rats (101±2 mm Hg and 326±10 bpm). The power of the low-frequency band of both AP and PI spectra, a marker of sympathetic modulation, was higher in WARs than in Wistar control rats. The high-frequency power of the PI spectra in normalized units, which is linked to cardiac vagal modulation, was lower in WARs. Both WARs and Wistar control rats had similar vagal tone (91±13 bpm vs 94±11 bpm, respectively), but sympathetic tone was higher in WARs (30±4 bpm vs 14±4 bpm). No differences were detected in the gain of evoked (1.32±0.1 ms/mm Hg vs 1.35±0.2 ms/mm Hg) or spontaneous (1.34±0.2 ms/mm Hg vs 2.04±0.2 ms/mm Hg) baroreflex sensitivity. The higher AP and HR and the autonomic imbalance (sympathetic predominance) in WARs might be associated with an increased risk of life-threatening cardiovascular events in this strain.

Effect of baroreceptor denervation on the autonomic control of arterial pressure in conscious mice

This study evaluated the role of arterial baroreceptors in arterial pressure (AP) and pulse interval (PI) regulation in conscious C57BL mice. Male animals, implanted with catheters in a femoral artery and a jugular vein, were submitted to sino-aortic (SAD), aortic (Ao-X) or carotid sinus denervation (Ca-X), 5 days prior to the experiments. After basal recording of AP, the lack of reflex bradycardia elicited by administration of phenylephrine was used to confirm the efficacy of SAD, and cardiac autonomic blockade with methylatropine and propranolol was performed. The AP and PI variability were calculated in the time and frequency domains (spectral analysis/fast Fourier transform) with the spectra quantified in low- (LF; 0.25-1 Hz) and high-frequency bands (HF; 1-5 Hz). Basal AP and AP variability were higher after SAD, Ao-X or Ca-X than in intact mice. Pulse interval was similar among the groups, whereas PI variability was lower after SAD. Atropine elicited a slight tachycardia in control mice but did not change PI after total or partial denervation. The bradycardia caused by propranolol was higher after SAD, Ao-X or Ca-X compared with intact mice. The increase in the variability of AP was accompanied by a marked increase in the LF and HF power of the AP spectra after baroreceptor denervation. The LF and HF power of the PI were reduced by SAD and by Ao-X or Ca-X. Therefore, both sino-aortic and partial baroreceptor denervation in mice elicits hypertension and a remarkable increase in AP variability and cardiac sympathetic tonus. Spectral analysis showed an important contribution of the baroreflex in the power of LF oscillations of the PI spectra. Both sets of baroreceptors seem to be equally important in the autonomic regulation of the cardiovascular system in mice.

Modeling the potential distribution of the invasive golden mussel Limnoperna fortunei in the Upper Paraguay River system using limnological variables

The invasive golden mussel, Limnoperna fortunei (Dunker, 1857), was introduced into the La Plata River estuary and quickly expanded upstream to the North, into the Paraguay and Paraná rivers. An ecological niche modeling approach, based on limnological variables, was used to predict the expansion of the golden mussel in the Paraguay River and its tributaries. We used three approaches to predict the geographic distribution: 1) the spatial distribution of calcium concentration and the saturation index for calcium carbonate (calcite); 2) the Genetic Algorithm for Rule-Set Production (GARP) model; and the 3) Maximum Entropy Method (Maxent) model. Other limnological variables such as temperature, dissolved oxygen, pH, and Total Suspended Solids (TSS) were used in the latter two cases. Important tributaries of the Paraguay River such as the Cuiabá and Miranda/Aquidauana rivers exhibit high risk of invasion, while lower risk was observed in the chemically dilute waters of the middle basin where shell calcification may be limited by low calcium concentrations and carbonate mineral undersaturation.

Myocardial performance in conscious streptozotocin diabetic rats

Background

In spite of a large amount of studies in anesthetized animals, isolated hearts, and in vitro cardiomyocytes, to our knowledge, myocardial function was never studied in conscious diabetic rats. Myocardial performance and the response to stress caused by dobutamine were examined in conscious rats, fifteen days after the onset of diabetes caused by streptozotocin (STZ). The protective effect of insulin was also investigated in STZ-diabetic rats.

Methods

Cardiac contractility and relaxation were evaluated by means of maximum positive (+dP/dt_max) and negative (-dP/dt_max) values of first derivative of left ventricular pressure over time. In addition, it was examined the myocardial response to stress caused by two dosages (1 and 15 μg/kg) of dobutamine. One-way analysis of variance (ANOVA) was used to compare differences among groups, and two-way ANOVA for repeated measure, followed by Tukey post hoc test, to compare the responses to dobutamine. Differences were considered significant if P < 0.05.

Results

Basal mean arterial pressure, heart rate, +dP/dt_max and -dP/dt_max were found decreased in STZ-diabetic rats, but unaltered in control rats treated with vehicle and STZ-diabetic rats treated with insulin. Therefore, insulin prevented the hemodynamic and myocardial function alterations observed in STZ-diabetic rats. Lower dosage of dobutamine increased heart rate, +dP/dt_max and -dP/dt_max only in STZ-diabetic rats, while the higher dosage promoted greater, but similar, responses in the three groups. In conclusion, the results indicate that myocardial function was remarkably attenuated in conscious STZ-diabetic rats. In addition, the lower dosage of dobutamine uncovered a greater responsiveness of the myocardium of STZ-diabetic rats. Insulin preserved myocardial function and the integrity of the response to dobutamine of STZ-diabetic rats.

Conclusion

The present study provides new data from conscious rats showing that the cardiomyopathy of this pathophysiological condition was expressed by low indices of contractility and relaxation. In addition, it was also demonstrated that these pathophysiological features were prevented by the treatment with insulin.

Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice

The goal of this study was to determine the baroreflex influence on systolic arterial pressure (SAP) and pulse interval (PI) variability in conscious mice. SAP and PI were measured in C57Bl/6J mice subjected to sinoaortic deafferentation (SAD, n = 21) or sham surgery ( n = 20). Average SAP and PI did not differ in SAD or control mice. In contrast, SAP variance was enhanced (21 ± 4 vs. 9.5 ± 1 mmHg2) and PI variance reduced (8.8 ± 2 vs. 26 ± 6 ms2) in SAD vs. control mice. High-frequency (HF: 1–5 Hz) SAP variability quantified by spectral analysis was greater in SAD (8.5 ± 2.0 mmHg2) compared with control (2.5 ± 0.2 mmHg2) mice, whereas low-frequency (LF: 0.1–1 Hz) SAP variability did not differ between the groups. Conversely, LF PI variability was markedly reduced in SAD mice (0.5 ± 0.1 vs. 10.8 ± 3.4 ms2). LF oscillations in SAP and PI were coherent in control mice (coherence = 0.68 ± 0.05), with changes in SAP leading changes in PI (phase = −1.41 ± 0.06 radians), but were not coherent in SAD mice (coherence = 0.08 ± 0.03). Blockade of parasympathetic drive with atropine decreased average PI, PI variance, and LF and HF PI variability in control ( n = 10) but had no effect in SAD ( n = 6) mice. In control mice, blockade of sympathetic cardiac receptors with propranolol increased average PI and decreased PI variance and LF PI variability ( n = 6). In SAD mice, propranolol increased average PI ( n = 6). In conclusion, baroreflex modulation of PI contributes to LF, but not HF PI variability, and is mediated by both sympathetic and parasympathetic drives in conscious mice.

Cardiovascular responses to chemoreflex activation with potassium cyanide or hypoxic hypoxia in awake rats

Although intravenous (iv) injection of potassium cyanide (KCN) activates the arterial chemoreflex, it has been questioned whether cytotoxic hypoxia reproduces a physiological stimulus such as hypoxic hypoxia (low inspired O2 tension). Thus, the goal of the present study was to compare the cardiovascular responses elicited by intravenous injection of KCN to those caused by hypoxic hypoxia in awake rats before and after bilateral ligature of carotid body arteries. We tested the hypothesis that hypoxic hypoxia activates the cardiovascular chemoreflex just as KCN does, causing an increase in arterial pressure and bradycardia. Intact adult Wistar rats received an intravenous injection of KCN (160 microg/kg) and were exposed to hypoxic hypoxia (7-5% O2 breathing) for 10-15 s at random while mean arterial pressure (MAP) and heart rate (HR) were measured. After the experiments, the animals were submitted to bilateral ligature of carotid body arteries or sham operation and the protocol was repeated on the subsequent day. Before surgery, all rats showed an abrupt rise in arterial pressure accompanied by a marked bradycardia in response to KCN or hypoxic hypoxia, with a very similar pattern. After surgery, these responses persisted only in the sham-operated group and were totally abolished in the ligature group. In conclusion, our data show that KCN is an appropriate stimulus to activate arterial chemoreflex because its cardiovascular responses are comparable to those induced by hypoxic hypoxia. Thus, the use of KCN as a tool to evaluate different aspects of the complex pattern of cardiovascular, respiratory, and behavioural responses to chemoreflex activation seems to be physiologically acceptable.

A 10-year follow-up of the outcome of lumbar microdiscectomy

STUDY DESIGN

A retrospective analysis of the outcome of lumbar microdiscectomy, with independent assessment of outcome.

OBJECTIVES

To explore whether the initial positive outcome after microdiscectomy is maintained at long-term follow-up.

SUMMARY OF BACKGROUND DATA

Previous reports on long-term outcome after lumbar disc surgery give conflicting messages about whether an initially positive surgical outcome is maintained throughout a 10-year period. This is partly due to differing methods and the failure to include initial outcome, thereby permitting assessment of possible deterioration in the quality of outcome.

METHODS

This study presents the initial and long-term outcome after lumbar microdiscectomy, with an independent assessment of outcome. Eighty-eight consecutive patients undergoing lumbar microdiscectomy were identified. Assessment at 10 years after surgery was obtained in 79 (90%) of the cases. The initial outcome was assessed retrospectively by an independent observer at 6 months after surgery using the Macnab classification. The final outcome Macnab classification was completed by postal questionnaire by the patients themselves, who also completed a modified Roland-Morris disability questionnaire.

RESULTS

A successful outcome at 6 months was achieved in 91% of the cases. At 10-year follow-up, this result declined slightly to an 83% success rate. However, there was no statistically significant difference between these outcome results. The long-term Macnab classification results correlated well with disability, as measured by the Roland-Morris score. Patient satisfaction with the results of microdiscectomy 10 years later was high.

CONCLUSIONS

Lumbar microdiscectomy achieves a high level of initial success, and this positive outcome is maintained at a 10-year follow-up.

[Electroencephalographic changes in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency]

Electroencephalographic changes have been detected in children with premature pubarche. These findings might be the result from past or current central nervous system dysfunction, or from increased sex steroids. In order to test the last assertion we have performed electroencephalographic studies in 10 patients (7F, 3M) with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, of whom 4 classic and 6 nonclassic forms of the syndrome. Traditional neurologic examination was performed in 7 patients, the result being considered normal in everyone, while evolutional neurologic examination detected hyperactive disturbance and attention deficit in two patients. In another patient, the clinical findings were compatible with delay of neuropsychomotor development. Quantitative electroencephalography with brain mapping in patients over three years-old (n = 9), and conventional EEG in the remaining patient, were considered abnormal for age in 8 patients (80%), the record being characterized as slow in 7 patients. The high rate of electroencephalographic changes in this sample, as well as in premature pubarche, suggests that these findings might result from high inappropriate for age androgenic levels, and warns about the importance of neurologic examination and follow-up in children with CAH.

The protective effect of ß-carotene on genotoxicity induced by cyclophosphamide

The influence of beta-carotene on the clastogenicity of the indirect-acting mutagen cyclophosphamide (CPA) was investigated in mice, in vivo, for the induction of chromosome aberrations in bone marrow cells (BM). beta-Carotene (0.5, 1.0, 2.0, 5.0, 10, 25, 50, 100 and 200 mg/kg) was administered by gavage for 5 consecutive days. 4 h after the last treatment with beta-carotene, the mice were injected intraperitoneally with CPA, and the BM cells were fixed after 16, 24 and 32 h for the evaluation of the frequency of chromosome aberrations. The results showed that beta-carotene was effective in reducing chromosomal damage induced by CPA with the increase of its concentration up to a level after which this effect was not observed. This anticlastogenicity was better detected when the cells were fixed at 32 h, although a tendency in reducing the CPA clastogenicity was already observed at 16 and 24 h. Our results suggest that beta-carotene provides significant protection against the genotoxicity of CPA, although no dose-effect relationship on the frequencies of cells with chromosomal aberrations was observed.