Acute kidney injury frequently accompanies sepsis. Endotoxin is known to reduce tissue levels of cAMP and low levels of cAMP have been associated with renal injury. We, therefore, hypothesized that endotoxin induced renal injury by activating phosphodiesterase 3 (PDE3) which metabolizes cAMP and that amrinone an inhibitor of PDE3 would prevent the renal injury.Animals were divided into three groups (n = 7/group): 1) Control (0.9% NaCl infusion without LPS); 2) LPS (0.9% NaCl infusion with LPS); 3) Amrinone+LPS (Amrinone infusion with LPS). Either lipopolysaccharide (LPS) or vehicle was injected via the jugular vein and the rats followed for 3 hours. We explored the expression of PDE3 isoenzymes and the concentrations of cAMP in the tissue.The PDE3B gene but not PDE3A was upregulated in the kidney of LPS group. Immunohistochemistry also showed that PDE3B was expressed in the distal tubule in the controls and LPS caused PDE3B expression in the proximal as well. However, PDE3A was not expressed in the kidney either in the control or LPS treated groups. Tissue level of cAMP was decreased after LPS and was associated with an increase in blood urea nitrogen, creatinine, ultrastructural proximal tubular changes, and expression of inducible nitric oxide synthase (iNOS) in the endotoxemic kidney. In septic animals the phosphodiesterase 3 inhibitor, amrinone, preserved the tissue cAMP level, renal structural changes, and attenuated the increased blood urea nitrogen, creatinine, and iNOS expression in the kidney.These findings suggest a significant role for PDE3B as an important mediator of LPS-induced acute kidney injury.
Na+/H+ exchanger regulation of intracellular pH (pHi) may play a key permissive role in the mitogen-induced vascular smooth muscle cell growth that occurs in systemic and pulmonary vascular remodeling. Spontaneously hypertensive rats (SHR) have increased Na+/H+ exchange in systemic vessels as well as greater systemic vascular remodeling compared with normotensive Wistar-Kyoto rats (WKY). In contrast to WKY, SHR demonstrate only mild pulmonary hypertension and no increased remodeling to hypoxia compared with WKY. We therefore wondered whether Na+/H+ exchange in pulmonary artery smooth muscle (PASM) of SHR might not be elevated compared with WKY. Baseline pHi, Vmax, pK0.5, and Hill coefficient were compared in 12- to 14-wk-old SHR and WKY PASM and aortic smooth muscle (AoSM) segments by ratio fluorescence spectroscopy. The Vmax, pK0.5, and Hill coefficient were significantly increased in SHR AoSM segments compared with WKY AoSM segments (53, 0.55, and 53%, respectively; P < 0.05). There were no differences in these values between SHR and WKY PASM segments, unlike the AoSM segments. We conclude that the Na+/H+ exchanger activity in PASM in the SHR is the same as in the WKY, which is in contrast to systemic arteries where Na+/H+ exchange is greater in the SHR.
The aim of this study was to compare, in women and men suspected of pulmonary embolism, the frequency, risk factors, diagnosis, and presentation of pulmonary embolism as well as the accuracy of the ventilation/perfusion scan (V/Q scan) as a diagnostic tool.Data were collected during a prospective study (the Prospective Investigation of Pulmonary Embolism Diagnosis) to establish the accuracy of the V/Q scan compared with pulmonary angiograms.Six tertiary medical centers in Massachusetts, Michigan, Connecticut, Pennsylvania, and North Carolina.Patients suspected of pulmonary embolism for whom a request was made for a V/Q scan or pulmonary angiogram (496 women and 406 men).Women 50 years old and under had a decreased frequency of pulmonary embolism compared with men of that age (16% vs 32%), but there was no difference in patients over 50 years old (Breslow-Day test, P less than .01). Risk factors for pulmonary embolism, the usefulness of the V/Q scan, and 1-year mortality were not different for women and men. Estrogen use in women was not associated with an increased frequency of pulmonary embolism, except in women using oral contraceptives who had undergone surgery within 3 months; four of five (80%) had emboli compared with four of 28 (14%) age-matched surgical patients not using estrogens (P less than .01).Women 50 years old and under (even young women using oral contraceptives) who were suspected of having pulmonary emboli and were enrolled in the Prospective Investigation of Pulmonary Embolism Diagnosis study had a smaller frequency of pulmonary embolism than men of that age, The risk factors for pulmonary embolism were the same for women and men, except that women using oral contraceptives had an increased risk of pulmonary embolism following surgery. Although the V/Q scan was a useful tool in the preliminary evaluation for pulmonary embolism in these women, a pulmonary angiogram was often needed for accurate diagnosis.
Intratracheal administration of low molecular mass (LMM) hyaluronan (200 kDa) results in greater neutrophil infiltration in the lungs of TLR4(-/-) mice compared with that in wild-type mice. In general, enhanced neutrophil infiltration in tissue is due to cell influx; however, neutrophil apoptosis also plays an important role. We have assessed the effects of TLR4 in the regulation of neutrophil apoptosis in response to administration of LMM hyaluronan. We found that apoptosis of inflammatory neutrophils is impaired in TLR4(-/-) mice, an effect that depends upon the IFN-β-mediated TRAIL/TRAILR system. IFN-β levels were decreased in LMM hyaluronan-treated TLR4-deficient neutrophils. The treatment of inflammatory neutrophils with IFN-β enhanced the levels of TRAIL and TRAILR 2. LMM hyaluronan-induced inflammatory neutrophil apoptosis was substantially prevented by anti-TRAIL neutralizing mAb. We conclude that decreased IFN-β levels decrease the activity of the TRAIL/TRAILR system in TLR4-deficient neutrophils, leading to impaired apoptosis of neutrophils and resulting in abnormal accumulation of neutrophils in the lungs of LMM hyaluronan-treated mice. Thus, TLR4 plays a novel homeostatic role in noninfectious lung inflammation by accelerating the elimination of inflammatory neutrophils.
Early diagnosis of pulmonary hypertension (PH) is critical for effective treatment and management. We aimed to develop and externally validate an artificial intelligence algorithm that could serve as a PH screening tool, based on analysis of a standard 12-lead ECG.
We recently found that low-molecular-weight hyaluronan was induced by cyclic stretch in lung fibroblasts and accumulated in lungs from animals with ventilator-induced lung injury. The low-molecular-weight hyaluronan produced by stretch increased interleukin-8 production in epithelial cells, and was accompanied by an upregulation of hyaluronan synthase-3 mRNA. We hypothesized that low-molecular-weight hyaluronan induced by high VT was dependent on hyaluronan synthase 3, and was associated with ventilator-induced lung injury. Effects of high VT ventilation in C57BL/6 wild-type and hyaluronan synthase-3 knockout mice were compared. Significantly increased neutrophil infiltration, macrophage inflammatory protein-2 production, and lung microvascular leak were found in wild-type animals ventilated with high VT. These reactions were significantly reduced in hyaluronan synthase-3 knockout mice, except the capillary leak. Wild-type mice ventilated with high VT were found to have increased low-molecular-weight hyaluronan in lung tissues and concomitant increased expression of hyaluronan synthase-3 mRNA, neither of which was found in hyaluronan synthase-3 knockout mice. We conclude that high VT induced low-molecular-weight hyaluronan production is dependent on de novo synthesis through hyaluronan synthase 3, and plays a role in the inflammatory response of ventilator-induced lung injury.
Chronic stresses, including the mechanical strain caused by hypertension or excess pulmonary ventilation pressure, lead to important clinical consequences, including hypertrophy and acute respiratory distress syndrome. Pathologic hypertrophy contributes to decreased organ function and, ultimately, organ failure; and cardiac and diabetic renal hypertrophy are major causes of morbidity and morality in the developed world. Likewise, acute respiratory distress syndrome is a serious potential side effect of mechanical pulmonary ventilation. Whereas the deleterious effects of chronic stress are well established, the molecular mechanisms by which these stresses affect cell function are still poorly characterized. gene 33 (also called mitogen-inducible gene-6, mig-6) is an immediate early gene that is transcriptionally induced by a divergent array of extracellular stimuli. The physiologic function of Gene 33 is unknown. Here we show that gene 33 mRNA levels increase sharply in response to a set of commonly occurring chronic stress stimuli: mechanical strain, vasoactive peptides, and diabetic nephropathy. Induction of gene 33 requires the stress-activated protein kinases (SAPKs)/c-Jun NH(2)-terminal kinases. This expression pattern suggests that gene 33 is a potential marker for diabetic nephropathy and other pathologic responses to persistent sublethal stress. The structure of Gene 33 indicates an adapter protein capable of binding monomeric GTPases of the Rho subfamily. Consistent with this, Gene 33 interacts in vivo and, in a GTP-dependent manner, in vitro with Cdc42Hs; and transient expression of Gene 33 results in the selective activation of the SAPKs. These results imply a reciprocal, positive feedback relationship between Gene 33 expression and SAPK activation. Expression of Gene 33 at sufficient levels may enable a compensatory reprogramming of cellular function in response to chronic stress, which may have pathophysiological consequences.
Purpose: To evaluate whether there were differences in acquisition of research grant support between male and female faculty at eight Harvard Medical School-affiliated institutions. Methods: Data were obtained from the participating institutions on all research grant applications submitted by full-time faculty from 2001 through 2003. Data were analyzed by gender and faculty rank of applicant, source of support (federal or nonfederal), funding outcome, amount of funding requested, and amount of funding awarded. Results: Data on 6319 grant applications submitted by 2480 faculty applicants were analyzed. Women represented 29% of investigators and submitted 26% of all grant requests. There were significant gender differences in the mean number of submissions per applicant (women 2.3, men 2.7), success rate (women 41%, men 45%), number of years requested (women 3.1, men 3.4), median annual amount requested (women $115,325, men $150,000), mean number of years awarded (women 2.9, men 3.2), and median annual amount awarded (women $98,094, men $125,000). After controlling for academic rank, grant success rates were not significantly different between women and men, although submission rates by women were significantly lower at the lowest faculty rank. Although there was no difference in the proportion of money awarded to money requested, women were awarded significantly less money than men at the ranks of instructor and associate professor. More men than women applied to the National Institutes of Health, which awarded higher dollar amounts than other funding sources. Conclusions: Gender disparity in grant funding is largely explained by gender disparities in academic rank. Controlling for rank, women and men were equally successful in acquiring grants. However, gender differences in grant application behavior at lower academic ranks also contribute to gender disparity in grant funding for medical science.
