Mild hypothermia combined with dexmedetomidine reduced brain, lung, and kidney damage in experimental acute focal ischemic stroke.

BACKGROUND: Sedatives and mild hypothermia alone may yield neuroprotective effects in acute ischemic stroke (AIS). However, the impact of this combination is still under investigation. We compared the effects of the combination of mild hypothermia or normothermia with propofol or dexmedetomidine on brain, lung, and kidney in experimental AIS. AIS-induced Wistar rats (n = 30) were randomly assigned, after 24 h, to normothermia or mild hypothermia (32-35 °C) with propofol or dexmedetomidine. Histologic injury score and molecular biomarkers were evaluated not only in brain, but also in lung and kidney. Hemodynamics, ventilatory parameters, and carotid Doppler ultrasonography were analyzed for 60 min. RESULTS: In brain: (1) hypothermia compared to normothermia, regardless of sedative, decreased tumor necrosis factor (TNF)-α expression and histologic injury score; (2) normothermia + dexmedetomidine reduced TNF-α and histologic injury score compared to normothermia + propofol; (3) hypothermia + dexmedetomidine increased zonula occludens-1 expression compared to normothermia + dexmedetomidine. In lungs: (1) hypothermia + propofol compared to normothermia + propofol reduced TNF-α and histologic injury score; (2) hypothermia + dexmedetomidine compared to normothermia + dexmedetomidine reduced histologic injury score. In kidneys: (1) hypothermia + dexmedetomidine compared to normothermia + dexmedetomidine decreased syndecan expression and histologic injury score; (2) hypothermia + dexmedetomidine compared to hypothermia + propofol decreased histologic injury score. CONCLUSIONS: In experimental AIS, the combination of mild hypothermia with dexmedetomidine reduced brain, lung, and kidney damage.

Testosterone Therapy and Diaphragm Performance in a Male Patient with COVID-19: A Case Report.

Low levels of testosterone may lead to reduced diaphragm excursion and inspiratory time during COVID-19 infection. We report the case of a 38-year-old man with a positive result on a reverse transcriptase-polymerase chain reaction test for SARS-CoV-2, admitted to the intensive care unit with acute respiratory failure. After several days on mechanical ventilation and use of rescue therapies, during the weaning phase, the patient presented dyspnea associated with low diaphragm performance (diaphragm thickness fraction, amplitude, and the excursion-time index during inspiration were 37%, 1.7 cm, and 2.6 cm/s, respectively) by ultrasonography and reduced testosterone levels (total testosterone, bioavailable testosterone and sex hormone binding globulin (SHBG) levels were 9.3 ng/dL, 5.8 ng/dL, and 10.5 nmol/L, respectively). Testosterone was administered three times 2 weeks apart (testosterone undecanoate 1000 mg/4 mL intramuscularly). Diaphragm performance improved significantly (diaphragm thickness fraction, amplitude, and the excursion-time index during inspiration were 70%, 2.4 cm, and 3.0 cm/s, respectively) 45 and 75 days after the first dose of testosterone. No adverse events were observed, although monitoring was required after testosterone administration. Testosterone replacement therapy led to good diaphragm performance in a male patient with COVID-19. This should be interpreted with caution due to the exploratory nature of the study.

Leptin administration during lactation leads to different nutritional, biometric, hemodynamic, and cardiac outcomes in prepubertal and adult female Wistar rats.

Literature reports that insults, such as hormonal disturbances, during critical periods of development may modulate organism physiology and metabolism favoring cardiovascular diseases (CVDs) later in life. Studies show that leptin administration during lactation leads to cardiovascular dysfunction in young and adult male Wistar rats. However, there are sex differences regarding CVD. Thus, the present work aimed to investigate neonatal leptin administration's consequences on different outcomes in female rats at prepubertal and adult age. Newborn Wistar female rats were divided into two groups, Leptin and Control, receiving daily subcutaneous injections of this adipokine (8 µg/100 g) or saline for the first 10 of 21 d of lactation. Nutritional, biometric, hemodynamic, and echocardiographic parameters, as well as maximal effort ergometer performance, were determined at postnatal days (PND) 30 and 150. Leptin group presented lower food intake (p = 0.0003) and higher feed efficiency (p = 0.0058) between PND 21 and 30. Differences concerning echocardiographic parameters revealed higher left ventricle internal diameter (LVID) in systole (p = 0.0051), as well as lower left ventricle ejection fraction (LVEF) (p = 0.0111) and fractional shortening (FS) (p = 0.0405) for this group at PND 30. Older rats treated with leptin during lactation presented only higher LVID in systole (p = 0.0270). Systolic blood pressure and maximum effort ergometer test performance was similar between groups at both ages. These data suggest that nutritional, biometric, and cardiac outcomes due to neonatal leptin administration in female rats are age-dependent.

Functional and transcriptomic recovery of infarcted mouse myocardium treated with bone marrow mononuclear cells.

Although bone marrow-derived mononuclear cells (BMNC) have been extensively used in cell therapy for cardiac diseases, little mechanistic information is available to support reports of their efficacy. To address this shortcoming, we compared structural and functional recovery and associated global gene expression profiles in post-ischaemic myocardium treated with BMNC transplantation. BMNC suspensions were injected into cardiac scar tissue 10 days after experimental myocardial infarction. Six weeks later, mice undergoing BMNC therapy were found to have normalized antibody repertoire and improved cardiac performance measured by ECG, treadmill exercise time and echocardiography. After functional testing, gene expression profiles in cardiac tissue were evaluated using high-density oligonucleotide arrays. Expression of more than 18% of the 11981 quantified unigenes was significantly altered in the infarcted hearts. BMNC therapy restored expression of 2099 (96.2%) of the genes that were altered by infarction but led to altered expression of 286 other genes, considered to be a side effect of the treatment. Transcriptional therapeutic efficacy, a metric calculated using a formula that incorporates both recovery and side effect of treatment, was 73%. In conclusion, our results confirm a beneficial role for bone marrow-derived cell therapy and provide new information on molecular mechanisms operating after BMNC transplantation on post ischemic heart failure in mice.

Ecocardiograma de alta resolução e o modelo de infarto do miocárdio em camundongos / High resolution echocardiography and the myocardial infarction model in mice

Objetivo: Avaliação do infarto do miocárdio (IM), induzido por isquemia e reperfusão em camundongos, por meio de análises ecocardiográficas, em equipamento específico para pequenos roedores. Medotologia: Camundongos machos e fêmeas C57BL/6 (oito semanas), pesando entre 20 e 25g, foram submetidos à indução do IM pelo protocolo isquemia e reperfusão (n=19), com um período de isquemia de 90 minutos e comparados a animais não infartados (n=10). Foram realizadas avaliações ecocardiográficas, antes do infarto e 8, 20 e 60 dias após a cirurgia com transdutor de alta resolução (30 MHz) específico para camundongos. Foram avaliados os diâmetros cavitários, fração de encurtamento pelo modo unidimensional e tempo de relaxamento isovolumétrico pelo Doppler, além de fração de ejeção calculada pelo método de Simpson, pelo modo bidimensional. Resultados: já na primeira análise, após o infarto do miocárdio, é possível evidenciar a dilatação do ventrículo esquerdo, em sístole (controle 2,10 +ou menos 0,43) mm versus infartado 2,83+ ou menos 0,46 mm, p<0,001) e diástole (controle 3,26+ ou menos 0,33 mm versus infartado 3,83 + ou menos 0,48 mm, p<0,01) e redução da fração de ejeção pelo método e Simpson (controle 74,63 + ou menos 8,29 versus infartado 62,58 + ou menos 11,62, p<0,05). Além disso, foi observado redução do tempo de relaxamento...

Reduced hemodynamic responses to physical and mental stress under low-dose rilmenidine in healthy subjects.

Activation of the sympathetic nervous system plays a major role in the pathogenesis and prognosis of cardiovascular diseases. Rilmenidine is an I(1)-imidazoline receptor agonist that reduces blood pressure by modulation of central sympathetic activity, but the effects of low-dose rilmenidine on the hemodynamic responses to physiological maneuvers that increase adrenergic drive is not known. To assess the effects of low-dose rilmenidine on the hemodynamic responses to stress, 32 healthy subjects (20-56 years old) underwent acute physical exercise (n = 15, individualized ramp protocol on treadmill) and mental stress (n = 17, word color Stroop and mental arithmetics tests) two hours after the oral administration of 0.5 mg of rilmenidine (RIL) or placebo (PLA) following a randomized, double-blind, placebo controlled crossover study. No subject complained of any side effect. Rilmenidine reduced peak exercise heart rate (PLA: 187 +/- 7; RIL: 181 +/- 9 bpm; P = 0.003), but did not modify peak aerobic power (VO(2max) - PLA: 41.7 +/- 6.2; RIL: 42.3 +/- 6.7 ml/kg/min; P = 0.26). During mental stress, rilmenidine inhibited the peak systolic (PLA: 123 +/- 10; RIL: 114 +/- 8 mmHg; P = 0.02) and diastolic (PLA: 86 +/- 7; RIL: 81 +/- 7 mmHg; P <0.05) blood pressure responses. In conclusion, rilmenidine reduced the hemodynamic response to physical and mental stress stimuli without limiting exercise capacity. These results support the concept that rilmenidine, at a dose lower than the ones recommended to treat hypertension, reduced the myocardial oxygen demand to stress and may carry potential clinical impact.