SGLT2 Inhibitors as Calorie Restriction Mimetics: Insights on Longevity Pathways and Age-Related Diseases.

Sodium-glucose cotransporter-2 (SGLT2) inhibitors induce glycosuria, reduce insulin levels, and promote fatty acid oxidation and ketogenesis. By promoting a nutrient deprivation state, SGLT2 inhibitors upregulate the energy deprivation sensors AMPK and SIRT1, inhibit the nutrient sensors mTOR and insulin/IGF1, and modulate the closely linked hypoxia-inducible factor (HIF)-2α/HIF-1α pathways. Phosphorylation of AMPK and upregulation of adiponectin and PPAR-α favor a reversal of the metabolic syndrome which have been linked to suppression of chronic inflammation. Downregulation of insulin/IGF1 pathways and mTOR signaling from a reduction in glucose and circulating amino acids promote cellular repair mechanisms, including autophagy and proteostasis which confer cellular stress resistance and attenuate cellular senescence. SIRT1, another energy sensor activated by NAD+ in nutrient-deficient states, is reciprocally activated by AMPK, and can deacetylate and activate transcription factors, such as PCG-1α, mitochondrial transcription factor A (TFAM), and nuclear factor E2-related factor (NRF)-2, that regulate mitochondrial biogenesis. FOXO3 transcription factor which target genes in stress resistance, is also activated by AMPK and SIRT1. Modulation of these pathways by SGLT2 inhibitors have been shown to alleviate metabolic diseases, attenuate vascular inflammation and arterial stiffness, improve mitochondrial function and reduce oxidative stress-induced tissue damage. Compared with other calorie restriction mimetics such as metformin, rapamycin, resveratrol, and NAD+ precursors, SGLT2 inhibitors appear to be the most promising in the treatment of aging-related diseases, due to their regulation of multiple longevity pathways that closely resembles that achieved by calorie restriction and their established efficacy in reducing cardiovascular events and all-cause mortality. Evidence is compelling for the role of SGLT2 inhibitors as a calorie restriction mimetic in anti-aging therapeutics.

Impact of gestational age on the clinical presentation and surgical outcome of necrotizing enterocolitis.

OBJECTIVE: This investigation tests the hypothesis that the clinical presentation and the outcome of necrotizing enterocolitis (NEC) vary with gestational age (GA). METHODS: All infants admitted to our center between October 1991 and September 2003 were evaluated weekly to identify confirmed cases of NEC. Based upon GA, these infants were divided into five groups: Extremely premature (EP, 23 to 26 weeks), very premature (VP, 27 to 29 weeks), moderately premature (MP, 30 to 34 weeks), near-term (NT, 35 to 36 weeks), and term (T, 37 to 42 weeks). RESULTS: A total of 202 infants developed NEC. The most common sign of NEC among EP infants was ileus (77%), followed by abdominal distention (71%), emesis (58%), pneumoperitoneum (54%), fixed intestinal loop (52%), gasless abdomen (42%) and bloody stools (17%). Intramural gas was detected in 100% of T but was present in only 29% of EP infants (P < 0.0001). Similarly, portal venous gas was common in T but infrequent in the EP infants (47 vs 10%, P < 0.0001). Despite a higher peritoneal drain insertion rate (31 vs 5%, P < 0.001) and a higher mortality rate (33 vs 10%, P = 0.05) in EP compared to T infants, other clinical outcomes were not different. CONCLUSIONS: The clinical presentation of NEC is different in EP compared to more mature infants; however, outcome among NEC survivors is similar across all GA. Reliance solely on observation of intramural or on portal venous gas in EP infants may lead to a delay or failure in the diagnosis.

Balloon angioplasty--branch pulmonary artery stenosis: results from the Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Balloon angioplasty for branch pulmonary artery stenosis was reported from 27 institutions to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. One hundred eighty-two procedures were performed in 156 patients ranging in age from 0.2 to 46.2 years (mean 7.7). Short-term angiographic appearance, hemodynamic results and immediate complications were recorded. Vessel dimension at the site of stenosis increased from 4.5 +/- 2.0 (mean +/- standard deviation) to 6.8 +/- 3.0 mm (p less than 0.001) with greater increases in vessel dimension at the site of stenosis if the balloon diameter was greater than 3 X the original dimension of the stenosis. There was no significant benefit related to age or prior surgical intervention. The mean peak systolic pressure gradient was reduced from 49 +/- 25 to 37 +/- 26 mm Hg (p less than 0.001) and pressure proximal to the stenosis decreased from 69 +/- 25 to 63 +/- 24 mm Hg (p less than 0.001). Complications occurred in 21 patients and included vessel rupture and death in 2 patients, vessel perforation or rupture with survival in 3, cardiac arrest and death in 1, paradoxical embolism and death in 1 and low output and death in 1. Balloon angioplasty for branch pulmonary artery stenosis increases vessel dimension at the site of stenosis, reduces systolic pressure gradient and to a minor degree, reduces proximal pressure. Long-term outcome and potential complications are as yet uncertain.

Spiral vein graft: an alternative method for relief of superior vena caval obstruction following the Mustard repair.

This report describes our experience with an 11-year-old girl with superior vena caval syndrome following an intra-atrial baffle for transposition of the great arteries. She underwent a saphenous spiral vein graft with excellent relief of the obstruction. This method is presented as an alternative to the use of cardiopulmonary bypass for baffle revision and direct anastomosis of the innominate vein to the left atrial appendage when the latter is not feasible.

Modified Fontan procedure. Methods to achieve direct anastomosis of right atrium to pulmonary artery.

Experience with Fontan operations suggests that techniques which utilize autogenous structures exclusively to achieve right atrium-pulmonary circuit connection may be preferred. Valves probably are not required in the circuit and in some cases have become obstructive with time. A large-diameter direct anastomosis of the right atrium to the pulmonary artery nearly always is possible and provides a modification of the Fontan procedure which combines favorable qualities of simplicity, all autogenous material, and posterior position which is free of the risks of compression. There also may be improved hemodynamics with this modification. Options to achieve this anastomosis depending on relations of the great arteries, previous operations, and other anatomic variations are described in eight patients.

Single ventricle with aortic outflow obstruction: operative repair by creation of double outlet to the aorta and application of the Fontan principle.

A new operation is described which allows the Fontan procedure to be used in patients having single ventricle accompanied by aortic outflow obstruction. Connection of the proximal pulmonary artery and valve to the aorta via a tubular prosthesis provides a second outlet of the ventricle to the aorta in order to effectively bypass subaortic obstruction. Anastomosis of a distal pulmonary artery to the right atrium and closure of the atrial septum by patch (Fontan procedure) complete the establishment of unrestricted pulmonary and systemic circulations in series.

Surgical treatment of coarctation of the aorta after balloon angioplasty.

This study was designed to assess the long-term effects of balloon angioplasty for coarctation of the aorta. Eleven asymptomatic children, aged 4 to 6 years, underwent balloon angioplasty. Mean peak gradient fell from 50.5 +/- 4.7 mm Hg before angioplasty to 21.7 +/- 3.1 immediately after angioplasty. Children were then followed up at 3 to 6 month intervals and were recatherized 5 to 14 months after balloon angioplasty. On the basis of these catheterization findings, patients were divided into three groups: group I--four patients, residual gradient less than 10 mm Hg and no anatomic abnormalities; Group II--three patients, increase of gradient to greater than 25 mm Hg, mean 34 mm Hg; Group III--four patients, aneurysmal dilatation in the area of the balloon angioplasty. The seven patients in groups II and III underwent elective resection of their coarctation at 7 to 28 months after balloon angioplasty with end-to-end anastomosis. Somatosensory evoked potentials were monitored during the operation. There were no operative deaths and no gradients between arm and leg pressures postoperatively. One patient had mild paresis of the lower extremities. Pathologic examination of the specimens revealed an absence of muscle and elastic lamella in the area of the aneurysms. This finding was present in all specimens regardless of whether there was aneurysmal dilatation. Neofibroelastic proliferation at the site of the tear was responsible for persistent gradients. Balloon angioplasty may result in aneurysmal formation and/or recurrent stenosis in the area of the tear necessitating elective surgical repair. Surgical treatment is the same as for native coarctation when done early after balloon angioplasty, but may be associated with increased risk because of the lack of collateral circulation. Continued follow-up of these lesions is necessary.

Hypoplastic left heart syndrome: successful palliation with a new operation.

A new operative procedure is described for the palliation of hypoplastic left heart syndrome. The operation consists of anastomosis of a tubular prosthesis between the proximal pulmonary artery and the aortic arch. A calibrated opening in the graft is brought into continuity with the distal pulmonary artery to provide balanced pulmonary and systemic blood flow. The atrial septum is excised and the ductus arteriosus ligated. A successful case report documents that this operation satisfies criteria required to reverse heart failure in infants with hypoplastic left heart syndrome.

Ligation of patent ductus arteriosus in premature infants.

In the operating room, 66 preterm infants weighing between 710 and 2,700 gm (23 less than 1,000 gm) underwent ligation of a patent ductus arteriosus (PDA). Respiratory distress syndrome was present in 53 patients; the rest had apnea-bradycardia syndrome. PDA ligation was indicated for intractable congestive heart failure in 52 patients or progressive respiratory failure in 14. There were no intraoperative deaths. Fifteen infants died 1 to 120 days postoperatively. Seven deaths resulted from intracranial bleeding, 3 from diffuse coagulopathy, and 1 from respiratory failure. The condition of patients with heart failure improved postoperatively, with the mean left atrium to aorta ratio reduced from 1.56 to 1.02 (p = 0.05). Respiratory function improved in 25 patients extubated by the third postoperative day. Late follow-up (one to five years) of the 51 survivors showed 1 late death. Seventeen survivors had roentgenographic evidence of bronchopulmonary dysplasia. Infants with bronchopulmonary dysplasia required longer postoperative ventilation (mean, 21.5 days compared with 4.75 days). Twenty-four infants were normal. Ligation of PDA in preterm infants has low intraoperative risk and improves the condition of those with heart and respiratory failure. Late follow-up showed good recovery of nearly two-thirds of the patients.

Prenatal or postnatal indomethacin exposure and neonatal gut injury associated with isolated intestinal perforation and necrotizing enterocolitis.

OBJECTIVE: To examine the role of indomethacin in neonatal gut injury. STUDY DESIGN: Infants born at gestational age 23 weeks and with birth weights 400-1200 g were included in this prospective prevalence study of neonatal gut injury. Infants with isolated intestinal perforation (IIP) confirmed at laparotomy or at autopsy or with necrotizing enterocolitis (NEC) were identified. Data were abstracted bi-weekly. RESULT: Among 992 study infants, 58 infants exposed solely to prenatal indomethacin did not show an increased rate of neonatal gut injury. Any postnatal indomethacin exposure (n=611) increased the odds of IIP (OR 4.17, CI, 1.24-14.08, P=0.02) but decreased the odds of NEC (OR 0.65, CI 0.43-0.97, P=0.04). There was a negative association between the timing of indomethacin-exposure and the odds of developing IIP (OR 0.30, CI 0.11-0.83, P=0.02). Compared with NEC, IIP occurred at an earlier age (P<0.05) and was more common (P<0.05) among infants who received early indomethacin (first dose at <12 h of age) to prevent intraventricular hemorrhage than among infants who were treated with late indomethacin for closure of a patent ductus arteriosus (PDA). Unlike the classic hemorrhagic ischemic lesions of NEC in which large areas of tissue were inflamed or necrotic, the IIP lesions were small and discrete. CONCLUSION: Early (<12 h) postnatal indomethacin exposure was associated with an increased odds of IIP in very low birth weight infants whereas its later use for closure of a PDA appeared to provide protection against NEC. The paradoxical effect of the timing of indomethacin on IIP versus on NEC may be related to the different pathogeneses of the two diseases. Our findings also suggest that PDA may contribute to NEC.

Sympathetic innervation improves the contractile performance of neonatal cardiac ventricular myocytes in culture.

We propose that sympathetic innervation could contribute to the improvement in cardiac contractility that normally occurs during neonatal life because these processes are developmentally coincident. Effects of sympathetic innervation were studied in primary cultures of isolated, not previously innervated ventricular cardiomyocytes from neonatal rats. Innervation was produced by addition of autologous neurons from the thoracolumbar sympathetic ganglia, and amplitude and frequency of myocyte contraction were measured by on-line video motion analysis. Sympathetic innervation significantly (P less than 0.0001) increased amplitude of contraction (by 34 +/- 8%) and decreased contraction frequency (by 36 +/- 3%). The effect of innervation on myocyte contractility was not attenuated by adrenoceptor blockade (10(-6) M propranolol and 10(-6) M phentolamine), but could be reproduced using medium conditioned by cocultures of neurons and myocytes. Sympathetic innervation improves the contractility of isolated cardiomyocytes, indicating that autonomic innervation contributes to maturation of cardiac function.

Contractile response to sympathetic innervation in neonatal ventricular cardiomyocytes of the spontaneously hypertensive rat.

Differences in cardiac development between spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto (WKY) controls are observed before the onset of hypertension. To determine whether intrinsic differences in myocardium or autonomic neurons might be responsible for these observations, we studied primary cultures of isolated, never previously innervated ventricular cardiomyocytes from neonatal rats of both strains, and sympathetic innervation was produced by addition of neurons from thoracolumbar sympathetic ganglia. Both same-strain and cross-strain innervation were compared. Amplitude and frequency of contraction were measured from video images of spontaneously contracting cells by on-line video motion analysis. Sympathetic innervation improved contractile function by 61% in SHR cardiomyocytes (p less than 0.001), an effect qualitatively similar to that previously reported for WKY cardiomyocytes. Contractile function of SHR cardiomyocytes cultured without sympathetic explants was 25% less than that of WKY cells (p less than 0.005), but the response of SHR cardiomyocytes to sympathetic innervation was twice as great as that of WKY myocytes (p less than 0.01). Cross-strain innervation experiments showed that sympathetic neurons from both strains were equally effective; interstrain differences were confined to the cardiomyocytes. Interstrain differences in cardiomyocyte contractile function and contractile response to sympathetic innervation are present before the onset of hypertension, and may in part account for alterations in cardiac function observed in prehypertensive SHR.

Age at death in the hypoplastic left heart syndrome: multivariate analysis and importance of the coronary arteries.

Survival analysis of 63 fatal cases of the hypoplastic left heart syndrome was undertaken to determine whether morphologic measurements related to coronary blood flow would predict the length of postnatal survival. Cross-sectional areas of the ascending aorta and proximal left and right coronary arteries, left and right ventricular mass, coronary artery dominance pattern, and the presence of discrete coarctation were determined from autopsy specimens. These values were used to construct survival functions using Cox regression. Survival was significantly prolonged in cases with larger cross-sectional areas of the left (p less than 0.005) and right (p less than 0.05) coronary arteries, right ventricular mass (p less than 0.005), and combined ventricular mass (p less than 0.005). A multivariate model was developed that included combined left and right coronary artery cross-sectional areas, right ventricular mass, and the ratio of combined coronary artery area-to-combined ventricular mass. This model also significantly (p less than 0.001) predicted instantaneous risk of death, and again larger covariate values were associated with longer survival. These results suggest that myocardial perfusion is an important determinant of survival in these infants.

Chronotropic responsiveness of developing sinoatrial and ventricular rat myocytes to autonomic agonists following adrenergic and cholinergic innervation in vitro.

The chronotropic responses of isolated sinoatrial node and ventricular muscle cells to neurotransmitters were compared in vitro with and without selective adrenergic and cholinergic innervation. Explants of either thoracolumbar sympathetic ganglion or sacrococcygeal spinal cord were added to cultures of newborn rat sinus node regions or ventricular apexes harvested before the onset of autonomic innervation in vivo. Catecholamine synthesis was detected by glyoxylic acid histofluorescence. Acetylcholine synthesis was indicated by monoclonal antibody labeling of choline acetyltransferase. After electrical or pharmacological stimulation of neurons, the chronotropic response of individual myocardial cells confirmed the presence of neuroeffector transmission; the nature of the myocyte response identified the stimulated neuron as either adrenergic or cholinergic. Chronotropic responses of all myocardial cells to norepinephrine or acetylcholine were transcribed on a recorder coupled to a video photoconductive cell monitor. Isolated sinoatrial node cells were supersensitive to norepinephrine and acetylcholine; thresholds were 3 x 10(-16) M and 6 x 10(-15) M, respectively. These sinoatrial node cells remained sensitive to both norepinephrine and acetylcholine after the development of innervation in vitro. Ventricular cells also were sensitive with thresholds of 3 x 10(-11) M and 6 x 10(-14) M to norepinephrine and acetylcholine, respectively. However, following in vitro innervation, ventricular cells were significantly less sensitive to norepinephrine and acetylcholine (thresholds 3 x 10(-9) M and 6 x 10(-11) M). These data are the first to demonstrate that neurotrophic modulation is not homogeneous throughout the myocardium and that it may be dependent on the specific myocardial cell innervated.

Techniques to avoid injury of the conduction tissue during the surgical treatment of corrected transposition.

Sequential atrioventricular conduction may be maintained during surgery in most patients with corrected transposition of the great arteries by operative techniques that include: (1) closure of the ventricular septal defect to the left side of the ventricular septum through a right atrial-right atrioventricular valve exposure, and (2) spiral pulmonary outflow patch (with or without pulmonary valve replacement), which enlarges the outflow tract posteriorly combined with posterior subvalvular resection of fibromuscular outflow tract obstruction. These techniques place operative manipulation posterior to the pulmonary anulus and on the left side of the septum so as to preserve the conduction tissue, which is located anterior to the pulmonary anulus and on the anterior rim of the ventricular septal defect in corrected transposition of the great arteries.

Morphologic determinants of coronary blood flow in the hypoplastic left heart syndrome.

The diameters of the ascending aorta, coronary ostia, and proximal coronary arteries were measured in autopsy specimens from 51 infants with hypoplastic left heart syndrome and 18 normal infant heart specimens. Standard cross sections were prepared from 35 of the hypoplastic left heart syndrome hearts, and histologic indices of myocardial viability and fibrosis were determined. The diameters of the coronary arteries and ostia in hypoplastic left heart syndrome were not different from the values in control specimens. Little fibrosis was found but extensive myocardial necrosis was present. The degree of fibrosis and necrosis did not correlate significantly with any of the arterial or ostial diameters. The extent of myocardial preservation in the hypoplastic left heart syndrome, which may substantially limit the success of surgical palliation, cannot be predicted from these morphologic measurements. The observed myocardial damage appeared to be acquired postnatally, implying that early vigorous treatment of these infants may be necessary to preserve myocardial function.

Correlation of function and morphology of neonatal rat and embryonic chick cultured cardiac and vascular muscle cells.

To develop morphological criteria which can be applied systematically for the identification of isolated cardiac and vascular muscle cells in mammalian and avian primary cultures, we have correlated structural and staining properties with excitability, contraction, and norepinephrine sensitivity of isolated muscle cells. The primary cultures of cardiac and vascular muscle contained muscle cells and nonmuscle cells. The muscle cells could be clearly identified by action potentials, contractility, and Masson's trichrome stain characteristics, similar to those of cells from intact source heart and blood vessels. Furthermore, the muscle cells were highly responsive to norepinephrine, showing unequivocal increases in contraction frequency. The sensitivity to norepinephrine was found to be very high (ED50 = 2.3 X 10(-9) M) Phase-contrast observation was sufficient to identify muscle cells only when those cells were contracting. There were no unequivocal morphological characteristics that distinguished between quiescent muscle cells and nonmuscle cells in the absence of histochemical staining. Ultrastructural examination by scanning electron microscopy failed to distinguish between muscle and nonmuscle cells. Histological staining was, therefore, the only reliable nonfunctional identification process that separated muscle cells from nonmuscle cells. Primary cultures, containing nonmuscle as well as muscle cells, are an important experimental preparation because the cellular heterogeneity probably minimizes muscle cell loss of function and phenotypic changes. The correlation we have established between cell staining and function will facilitate exploration of single cell properties, which together constitute hearts and blood vessels.