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PURPOSE: Hypertension is one of the major causes of cardiovascular morbidity and mortality in the USA and disproportionately affects Black women. Endothelial-derived nitric oxide (eNO) substantially regulates blood pressure in humans, and impaired NO-mediated vasodilation has been reported in the Black population. Previous studies using an NO synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA) did not fully determine the NO contribution to blood pressure because of baroreflex buffering. Therefore, in the present study we used trimethaphan, a ganglionic blocker, to inhibit baroreflex buffering and study NO modulation of blood pressure in Black women during L-NMMA infusion. METHODS: L-NMMA at doses of 250 µg/kg per minute was infused in combination with trimethaphan at doses of 4 mg/min to eliminate baroreflex mechanisms. Heart rate (HR) was obtained with continuous electrocardiogram monitoring, and continuous blood pressure was measured with the volume clamp method. The increase in systolic blood pressure (SBP) during both infusions was used to estimate the contribution of NO to blood pressure. RESULTS: Ten Black (age range 30-50 years, body mass index [BMI] 30-45 kg/m2), and nine White women (age range 30-50 years, body mass index 30-45 kg/m2) were enrolled in this study. During autonomic blockade, there was no difference in the decrease in SBP between Black and White women (- 20 ± 16.45 vs. - 24 ± 15.49 mm Hg, respectively; P = 0.659). When autonomic blockade was combined with L-NMMA, Black women had a significant increase in SBP compared to White women (54 ± 13.62 vs. 39 ± 09.64 mm Hg, respectively; P = 0.022, respectively). CONCLUSION: Autonomic blood pressure regulation was similar between Black and White women. However, NO contribution to blood pressure was significantly greater in Black women compared to White women. REGISTRATION: ClinicalTrials.gov: NCT01122407.
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Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous autonomic disorder. All patients have exaggerated tachycardia upon standing, but the pathophysiology may be diverse. We present a young adult Thai male with a chief complaint of palpitations while in an upright posture since childhood. The patient underwent a modified Ewing test battery which included standing test, deep breathing, and Valsalva maneuver. His heart rate increased more than 30 beats per minute (bpm) during repeated active stand tests (65 to 110 bpm and 77 to 108 bpm), while upright diastolic blood pressure increased more than 10 mmHg. Normal Valsalva ratio (2.01 and 1.86) and baseline heart rate variability (HFRRI = 4030.24 ms2 and 643.92 ms2) indicated intact vagal function. High low-frequency systolic blood pressure variability (LFSBP = 20.93 mmHg2), increased systolic blood pressure overshoot in phase IV of Valsalva (42 mmHg), and increased upright diastolic blood pressure indicated a hyperadrenergic state. In conclusion, the overall autonomic profile was compatible with hyperadrenergic POTS. Thus, we confirmed the first male POTS case reported in Thailand. We demonstrated the importance of autonomic function testing with continuous measurements to confirm POTS. There is a need for further research in POTS in Thailand.
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The remarkable capabilities of generative artificial intelligence and large language models (LLMs) such as ChatGPT have delighted users around the world. Educators have regarded these tools as either a cause for great concern, an opportunity to educate students on cutting-edge technology, or often some combination of the two. Throughout the Fall 2023 semester, we explored the use of ChatGPT (and Bard, among other LLMs) in a graduate level numerical and statistical methods course for PhD-level bioengineers. In this article we share examples of this ChatGPT content, our observations on what worked best in our course, and speculate on how bioengineering students may be best served by this technology in the future.