Subacute Exposure to Gaseous Pollutants from Diesel Engine Exhaust Attenuates Capsaicin-Induced Cardio-Pulmonary Reflex Responses Involving Oxidant Stress Mechanisms in Adult Wistar Rats.

Intravenous injection of capsaicin produces vagal-mediated protective cardio-pulmonary (CP) reflexes manifesting as tachypnea, bradycardia, and triphasic blood pressure (BP) response in anesthetized rats. Particulate matter from diesel engine exhaust has been reported to attenuate these reflexes. However, the effects of gaseous constituents of diesel exhaust are not known. Therefore, the present study was designed to investigate the effects of gaseous pollutants in diesel exhaust, on capsaicin-induced CP reflexes in rat model. Adult male rats were randomly assigned to three groups: Non-exposed (NE) group, filtered diesel exhaust-exposed (FDE) group and N-acetyl cysteine (NAC)-treated FDE group. FDE group of rats (n = 6) were exposed to filtered diesel exhaust for 5 h a day for 5 days (D1-D5), and were taken for dissection on day 6 (D6), while NE group of rats (n = 6) remained unexposed. On D6, rats were anesthetized, following which jugular vein was cannulated for injection of chemicals, and femoral artery was cannulated to record the BP. Lead II electrocardiogram and respiratory movements were also recorded. Results show that intravenous injection of capsaicin (0.1 ml; 10 µg/kg) produced immediate tachypneic, hyperventilatory, hypotensive, and bradycardiac responses in both NE and FDE groups of rats. However, these capsaicin-induced CP responses were significantly attenuated in FDE group as compared to the NE group of rats. Further, FDE-induced attenuation of capsaicin-evoked CP responses were diminished in the N-acetyl cysteine-treated FDE rats. These findings demonstrate that oxidant stress mechanisms could possibly be involved in inhibition of CP reflexes by gaseous pollutants in diesel engine exhaust.

Patient-reported cognitive impairments and objective neuropsychological deficits in young sarcoma patients undergoing chemotherapy and its comparison to healthy controls: A tertiary health care study from India.

The study aims to investigate the patient-reported cognitive deficits and objective neuropsychological functions in younger adult (YA) sarcoma patients (16-40 years of age). Ninety patients and 30 age-matched healthy controls from a single tertiary healthcare hospital, were recruited into four groups: Pre-chemotherapy (Pre Cx), During chemotherapy (During Cx), Post-chemotherapy (Post Cx) and Controls. Neurocognitive functions were assessed subjectively using FACT-Cog v3 questionnaire; objectively using ACE-III and neuropsychological tests (NPT). FACT-Cog scores of During Cx (P = .041) and Post Cx (P = .008) groups were significantly lower than Pre Cx group. ACE-III scores of During Cx (P = .048) and Post Cx (P = .043) groups were lower as compared to Pre Cx group. In addition, reaction times and accuracies of the NPT (Flanker's, Sternberg's and Emotional Stroop tests) were worse (P < .05) in During Cx and Post Cx groups as compared to either Pre Cx or control groups. In the Post Cx group, the dose of chemotherapy showed significant negative correlation with the Sternberg reaction time (P = .040) as well as the scores of language (P = .047), and attention (P = .044) domains of ACE-III. Observations demonstrate that cancer/chemotherapy-related neurocognitive deficits fail to improve even after cessation of treatment, and high dosage of chemotherapy used, could be an underlying factor. This emphasizes the need for developing 'model of care' in these patients for monitoring the side effects, and possible titration in the therapeutic regimen for sarcoma in YA.

Planning and implementation of participant-centric group activity on research methodology: perceptions of postgraduate medical students in physiology.

Knowledge about the key steps in "research methodology" is necessary for all postgraduate students who are enrolled in the medical profession. The objective of the present study was to plan, design, and implement a participant-centric postgraduate skill development activity to inculcate the key principles and components of research methodology. It included 3 goal-oriented component group exercises, namely, 1) framing a research question, 2) critiquing a research article, and 3) writing a research protocol. Out of 25 eligible postgraduate students of our department, 20 participated in all three component group exercises, and they were included in the study. Feedback was obtained from them on a five-point Likert scale after the group exercises. In addition, students were also asked to provide open-ended comments for further improvement of the session. Data from participants' feedback suggested that the majority of the participants expressed satisfaction regarding the plan, conduct, and learning experience of the postgraduate activity. Therefore, participant-centric group activity could be an innovative approach in postgraduate medical education to inculcate the basics of research methodology. It can provide additional emphasis on the components of self-directed learning through individual exercises and unsupervised group dynamics. Supervised group dynamics can inculcate skills in critical thinking, acceptance, communication skills, and teamwork.NEW & NOTEWORTHY Postgraduate medical education is underpinned by supervised and unsupervised learning processes. The current study incorporates an innovative approach to inculcate the basic skills of "research methodology" through three goal-oriented participant-centric group exercises, namely, 1) framing a research question, 2) critiquing a research article, and 3) writing a research protocol. The activities encompass components of self-directed learning through unsupervised group dynamics. They focus on critical thinking, acceptance, communication skills, and teamwork during supervised group dynamics.

Subthreshold Doses of Inflammatory Mediators potentiate one another to Elicit Reflex Cardiorespiratory Responses in Anesthetized Rats.

BACKGROUND: Reflex cardio-vascular and respiratory (CVR) alterations evoked by intra-arterial instillation of nociceptive agents are termed vasosensory reflexes. Such responses elicited by optimal doses of inflammatory mediators have been described in our earlier work. OBJECTIVE: The present study was designed to evaluate the interactions between subthreshold doses of inflammatory mediators on perivascular nociceptive afferents in urethane anesthetized rats. METHODS: Healthy male adult rats (Charles-Foster strain) were anesthetized with an intraperitoneal injection of urethane. After anesthesia, the right femoral artery was cannulated. Respiratory movements, blood pressure, and electrocardiogram were recorded. The interactions between subthreshold doses of algogens in the elicitation of vasosensory reflex responses were studied by instillation of bradykinin (1 nM) and histamine (100 µM) into the femoral artery one after the other, in either temporal combination in separate groups of rats. The CVR responses obtained in these groups were then compared with the responses produced by 100 µM histamine and 1 nM bradykinin in saline-pretreated groups, which served as control. RESULTS: Subthreshold doses of histamine elicited transient tachypnoeic, hyperventilatory, hypotensive, and bradycardiac responses, in rats pretreated with subthreshold doses of bradykinin [P <0.01, two-sided Dunnett's test] but not in saline pretreated groups [P >0.05, two-sided Dunnett's test]. Similar responses were elicited by bradykinin after histamine pretreatment compared to the saline-pretreated group. Furthermore, CVR responses produced by histamine in the bradykinin-pretreated group were greater in magnitude as compared to bradykinin-induced responses in the histamine-pretreated group [P <0.05, two-sided Dunnett's test]. CONCLUSION: The present study demonstrates that both bradykinin and histamine potentiate one another in the elicitation of vasosensory reflex responses, and bradykinin is a better potentiator than histamine at the level of perivascular nociceptive afferents in producing reflex CVR changes.

GPIIb/IIIa Receptor Targeted Rutin Loaded Liposomes for Site-Specific Antithrombotic Effect.

Rutin (RUT) is a flavonoid obtained from a natural source and is reported for antithrombotic potential, but its delivery remains challenging because of its poor solubility and bioavailability. In this research, we have fabricated novel rutin loaded liposomes (RUT-LIPO, nontargeted), liposomes conjugated with RGD peptide (RGD-RUT-LIPO, targeted), and abciximab (ABX-RUT-LIPO, targeted) by ethanol injection method. The particle size, ζ potential, and morphology of prepared liposomes were analyzed by using DLS, SEM, and TEM techniques. The conjugation of targeting moiety on the surface of targeted liposomes was confirmed by XPS analysis and Bradford assay. In vitro assessment such as blood clot assay, aPTT assay, PT assay, and platelet aggregation analysis was performed using human blood which showed the superior antithrombotic potential of ABX-RUT-LIPO and RGD-RUT-LIPO liposomes. The clot targeting efficiency was evaluated by in vitro imaging and confocal laser scanning microscopy. A significant (P < 0.05) rise in the affinity of targeted liposomes toward activated platelets was demonstrated that revealed their remarkable potential in inhibiting thrombus formation. Furthermore, an in vivo study executed on Sprague Dawley rats (FeCl3 model) demonstrated improved antithrombotic activity of RGD-RUT-LIPO and ABX-RUT-LIPO compared with pure drug. The pharmacokinetic study performed on rats demonstrates the increase in bioavailability when administered as liposomal formulation as compared to RUT. Moreover, the tail bleeding assay and clotting time study (Swiss Albino mice) indicated a better antithrombotic efficacy of targeted liposomes than control preparations. Additionally, biocompatibility of liposomal formulations was determined by an in vitro hemolysis study and cytotoxicity assay, which showed that they were hemocompatible and safe for human use. A histopathology study on rats suggested no severe toxicity of prepared liposomal formulations. Thus, RUT encapsulated nontargeted and targeted liposomes exhibited superior antithrombotic potential over RUT and could be used as a promising carrier for future use.

Ipsilateral somatic nerves mediate histamine-induced vasosensory reflex responses involving perivascular afferents in rat models.

Reflex cardiorespiratory alterations elicited after instillation of nociceptive agents intra-arterially (i.a) are termed as 'vasosensory reflex responses'. The present study was designed to evaluate such responses produced after i.a. instillation of histamine (1 mM; 10 mM; 100 mM) and to delineate the pathways i.e. the afferents and efferents mediating these responses. Blood pressure, electrocardiogram and respiratory excursions were recorded before and after injecting saline/histamine, in a local segment of femoral artery in urethane anesthetized rats. Paw edema and latencies of responses were also estimated. Separate groups of experiments were conducted to demonstrate the involvement of somatic nerves in mediating histamine-induced responses after ipsilateral femoral and sciatic nerve sectioning (+NX) and lignocaine pre-treatment (+Ligno). In addition, another set of experiments was performed after bilateral vagotomy (+VagX) and the responses after histamine instillation were studied. Histamine produced concentration-dependent hypotensive, bradycardiac, tachypnoeic and hyperventilatory responses of shorter latencies (2-7 s) favouring the neural mechanisms in eliciting the responses. Instillation of saline (time matched control) in a similar fashion produced no response, excluding the possibilities of ischemic/stretch effects. Paw edema was absent in both hind limbs indicating that the histamine did not reach the paws and did not spill out into the systemic circulation. +NX, +VagX, +Ligno attenuated histamine-induced cardiorespiratory responses significantly. These observations conclude that instillation of 10 mM of histamine produces optimal vasosensory reflex responses originating from the local vascular bed; afferents and efferents of which are mostly located in ipsilateral somatic and vagus nerves respectively.

Intra-arterial Instillation of a Nociceptive Agent Modulates Cardiorespiratory Parameters Involving 5-HT3 and TRPV1 Receptors in Anesthetized Rats.

BACKGROUND: Since long back, it has been a matter of discussion regarding the role of peripheral blood vessels in the regulation of cardiorespiratory (CVR) system. OBJECTIVE: The role of 5-HT3 and TRPV1 receptors present on perivascular nerves in elicitation of CVR reflexes was examined after intra-arterial instillation of bradykinin in urethane anesthetized rats. MATERIALS AND METHODS: Femoral artery was cannulated retrogradely and was utilized for the instillation of saline/agonist/antagonist and recording of blood pressure (BP), using a double ported 24G cannula. BP, respiration and ECG were recorded for 30 min after bradykinin (1 µM) in the absence or presence of antagonists. RESULTS: Instillation of bradykinin produced immediate hypotensive (40%), bradycardiac (17%), tachypnoeic (45%) and hyperventilatory (96%) responses of shorter latencies (5-8 s) favoring the neural mechanisms in producing the responses. In lignocaine (2%) pretreated animals, bradykinin- induced hypotensive (10%), bradycardiac (1.7%), tachypnoeic (13%) and hyperventilatory (13%) responses attenuated significantly. Pretreatment with ondansetron (100 µg/kg), 5-HT3-antagonist attenuated the hypotensive (10%), bradycardiac (1.7%), tachypnoeic (11%) and hyperventilatory (11%) responses significantly. Pretreatment with capsazepine (1 mg/kg), transient receptor potential vanilloid 1- antagonist blocked the hypotensive (5%), bradycardiac (1.2%), tachypnoeic (6%) and hyperventilatory (6%) responses significantly. CONCLUSION: In conclusion, presence of a nociceptive agent in the local segment of an artery evokes vasosensory reflex responses modulating CVR parameters involving TRPV1 and 5-HT3 receptors present on the perivascular sensory nerve terminals in anesthetized rats.

Algogen-induced vasosensory reflexes modulate short-term heart rate variability parameters in experimental rat models.

OBJECTIVES: The present work was designed to study the modulatory effects of algogen-induced vasosensory reflex responses on short-term heart rate variability (HRV) parameters in naïve and vagotomized rat models. METHODS: In this study, vasosensory reflex responses were elicited by instilling algogens (bradykinin/histamine), a component of inflammatory mediators into a local segment of medium-sized peripheral blood vessel (femoral artery) while a continuous electrocardiogram (ECG) was recorded. Short-term (5 min) ECG segments obtained from original recordings were examined in detail and relevant data of HRV parameters were pooled. Time domain and frequency domain analyses were performed using dedicated software (LabChart 8, AD Instruments®, Australia) and results were analyzed. RESULTS: Bradykinin-induced vasosensory reflexes caused significant alterations in both time domain and frequency domain HRV parameters as compared to the time-matched saline control group. Instillation of bradykinin caused a transient increase in NN interval, RMSSD, TSP, HF power (HFP) along with a decrease in the standard deviation of all normal NN intervals (SDNN), SDNN/RMSSD, LF power (LFP), LFP/HFP. Histamine produced a similar pattern of responses, but HRV alterations were less pronounced compared to those with bradykinin. Further analysis revealed that algogen-induced vasosensory reflex responses caused an increase in the parasympathetic influence on the heart accompanied by a decrease in sympathetic influence. In addition, HRV modulation by algogen-induced vasosensory reflexes was significantly attenuated in vagotomized rats, illustrating the principal role of vagus in the reflex HRV modulation. CONCLUSIONS: The present study proposes a novel hypothesis regarding the cardio-protective role of inflammatory mediators during acute stress, by potentiating the vagal impact and attenuating the sympathetic impact on the heart.

Retrograde cannulation of femoral artery: A novel experimental design for precise elicitation of vasosensory reflexes in anesthetized rats.

Vasosensory reflex responses are elicited by instillation of nociceptive agents in a segment of peripheral blood vessel. A novel method for the stimulation of perivascular afferents was designed by retrograde cannulation of femoral artery, using a 24G, double ported polyethylene cannula. The vertical port of which was used to inject the algogen into the artery and horizontal port to measure the BP continuously, as this port was connected to the pressure transducer. Previously, separate carotid artery cannulation was used for the BP recording. But our experimental design excluded the need for carotid artery cannulation that might compromise the circulation to the CNS centers mediating cardiorespiratory reflex responses. After cannulation, the proximal end of femoral artery became an end artery and the drugs were instilled retrogradely. The volume of chemicals was kept minimal (100 µl) and the ipsilateral femoral vein was also ligated. These measures made sure that the instilled drug remained in a local segment of femoral artery and did not spill out to the systemic circulation. Further, there was no increase in the water content of ipsilateral paw as compared to the contralateral paw. This finding also substantiates our proposition regarding minimal systemic spillage.•The femoral artery is cannulated by a double ported cannula.•This cannula helps instillation of algogen and BP measurement simultaneously.•Retrograde instillation helps to deposit the algogen in a local segment of femoral artery.