Recent studies showed that taurine, a sulphonic amino acid, could decrease blood pressure and increase sympathoadrenal tone in DoCA-salt-treated hypertensive rats. To determine whether taurine exerts its antihypertensive action in man in a similar fashion, we studied the effect of oral administration of taurine (6 g for 7 days) on blood pressure and plasma catecholamines in 19 young patients with borderline hypertension in a double-blind, placebo-controlled fashion. Systolic blood pressure in the 10 patients who were treated with taurine decreased by 9.0 ± 2.9 mm Hg (mean ± SE; p < .05 by paired t test), compared with a 2.7 + 2.3 mm Hg decrease (NS) in the nine patients treated with placebo and diastolic blood pressure in the taurine-treated patients decreased by 4.1 + 1.7 mm Hg (p < .05) compared with 1.2 ± 3.0 mm Hg (NS) in the placebo-treated subjects. In the patients receiving taurine plasma epinephrine (E) decreased significantly, with a negligible decrease in plasma norepinephrine (NE). The effect of taurine on plasma catecholamines and the response of plasma E after the stimulation with glucagon was also studied in 12 borderline hypertensive and nine agematched normotensive subjects. Basal plasma E was significantly higher in borderline hypertensive than in normal subjects, but basal plasma NE did not differ in the two groups. The intravenous bolus injection of glucagon (1 mg) caused a rapid and transient increase in plasma E in each subject studied; plasma E reached a peak concentration 2 to 5 min after the injection of glucagon and thereafter declined rapidly to the baseline level. The overall response of plasma E to glucagon stimulation was significantly (p < .01) greater in the borderline hypertensive than in the normotensive subjects. Taurine not only reduced mean blood pressure and basal plasma E, but also attenuated the increased response to glucagon in the borderline hypertensive subjects. In the normotensive subjects, however, the administration of taurine did not significantly change blood pressure, basal plasma catecholamines, or the response of plasma E to glucagon. Overall, there was a direct correlation (r = .670, p < .01) between the decrements in mean blood pressure and those in plasma E after taurine in the 22 borderline hypertensive subjects. Evidence presented suggests, therefore, that sympathoadrenal tone is increased in young borderline hypertensive individuals, and that oral administration of taurine attenuates increased tone, leading to the reduction of blood pressure. Circulation 75, No. 3, 525-532, 1987. YOUNG PATIENTS with borderline hypertension are at least three times more likely to develop established essential hypertension than age-matched normotensive subjects.1'2 Thus, young patients with borderline hypertension have been of particular interest to investigators because they may provide insight into the pathogenesis of essential hypertension. The majority of studies have reported increased average circulating norepinephrine levels in borderline hypertensive sub-

BackgroundLiquid biopsies enable the detection of circulating tumor DNA (ctDNA). However, the clinical significance of KRAS-mutated ctDNA for pancreatic cancer has been inconsistent with respect to its prognostic and predictive potential.Methods and findingsA total of 422 blood samples were collected from 78 patients undergoing treatments for localized and metastatic pancreatic ductal adenocarcinoma. KRAS mutation in tissues and KRAS ctDNA levels in plasma were determined by RASKET and droplet digital polymerase chain reaction. Longitudinal monitoring of KRAS ctDNA was performed to assess its significance for predicting recurrence and prognosis and for evaluating therapeutic responses to chemotherapy compared with carbohydrate antigen 19–9 (CA19-9). In 67 tumor tissues, discrepancies in point mutations of KRAS were rarely observed among individual patients, implying that one targeted point mutation of KRAS can be determined in tumor tissues prior to longitudinal blood monitoring. One-time blood assessment of KRAS-mutated ctDNA before surgery or chemotherapy was not clearly associated with recurrence and prognosis. Sequential blood monitoring was performed in 39 patients who underwent surgery for potentially resectable tumors. Increased CA19-9 levels were significantly associated with recurrence, but not prognosis (P<0.001, P = 1.0, respectively), whereas emergence of KRAS ctDNA was significantly associated with prognosis (P<0.001) regardless of recurrence. Furthermore, in 39 patients who did not undergo surgery, detection of KRAS ctDNA was a predictive factor for prognosis (P = 0.005). Multivariate analysis revealed that detection of KRAS ctDNA was the only independent prognostic factor regardless of tumor resection (hazard ratios = 54.5 for patients who underwent surgery and 10.1 for patients who did not undergo surgery; P<0.001 for both). Patients without emergence of KRAS ctDNA within 1 year after surgery showed significantly better prognosis irrespective of recurrence (P<0.001). No detection or disappearance of KRAS ctDNA within 6 months of treatment was significantly correlated with therapeutic responses to first-line chemotherapy (P<0.001). Changes in KRAS status provided critical information for the prediction of therapeutic responses.ConclusionsOur study showed for the first time that detection of KRAS ctDNA levels within a short period enables the prediction of prognosis and therapeutic responses in patients with pancreatic cancer.

Hypoparathyroidism is a disease of chronic hypocalcemia and hyperphosphatemia due to a deficiency of parathyroid hormone (PTH). PTH and analogs of the hormone are of interest as potential therapies. Accordingly, we examined the pharmacological properties of a long-acting PTH analog, [Ala1,3,12,18,22, Gln10,Arg11,Trp14,Lys26]-PTH(1–14)/PTHrP(15–36) (LA–PTH) in thyroparathyroidectomized (TPTX) rats, a model of HP, as well as in normal monkeys. In TPTX rats, a single intra-venous administration of LA-PTH at a dose of 0.9 nmol/kg increased serum calcium (sCa) and decreased serum phosphate (sPi) to near-normal levels for longer than 48 hours, while PTH(1–34) and PTH(1–84), each injected at a dose 80-fold higher than that used for LA-PTH, increased sCa and decreased sPi only modestly and transiently (< 6 hours). LA-PTH also exhibited enhanced and prolonged efficacy versus PTH(1–34) and PTH(1–84) for elevating sCa when administered subcutaneously (SC) into monkeys. Daily SC administration of LA-PTH (1.8 nmol/kg) into TPTX rats for 28-days elevated sCa to near normal levels without causing hypercalciuria or increasing bone resorption markers, a desirable goal in the treatment of hypoparathyroidism. The results are supportive of further study of long-acting PTH analogs as potential therapies for patients with hypoparathyroidism.

Conflict of interest: MNW and HMK are coinventors on a pending patent (US patent application 16/333,546) regarding the use of SIK inhibitors for osteoporosis. MNW and TJG receive research support from Radius Health. MNW and HMK receive research support from Galapagos NV.

Parathyroid hormone (PTH) is essential for calcium homeostasis and its action is mediated by the PTH type 1 receptor (PTHR1), a class B G-protein-coupled receptor. Hypoparathyroidism and osteoporosis can be treated with PTH injections; however, no orally effective PTH analogue is available. Here we show that PCO371 is a novel, orally active small molecule that acts as a full agonist of PTHR1. PCO371 does not affect the PTH type 2 receptor (PTHR2), and analysis using PTHR1–PTHR2 chimeric receptors indicated that Proline 415 of PTHR1 is critical for PCO371-mediated PTHR1 activation. Oral administration of PCO371 to osteopenic rats provokes a significant increase in bone turnover with limited increase in bone mass. In hypocalcemic rats, PCO371 restores serum calcium levels without increasing urinary calcium, and with stronger and longer-lasting effects than PTH injections. These results strongly suggest that PCO371 can provide a new treatment option for PTH-related disorders, including hypoparathyroidism.