Inhibitors of catechol-O-methyltransferase sensitize mice to pain

BACKGROUND AND PURPOSE

Catechol-O-methyltransferase (COMT) inhibitors are used in Parkinson''s disease in which pain is an important symptom. COMT polymorphisms modulate pain and opioid analgesia in humans. In rats, COMT inhibitors have been shown to be pro-nociceptive in acute pain models, but also to attenuate allodynia and hyperalgesia in a model of diabetic neuropathy. Here, we have assessed the effects of acute and repeated administrations of COMT inhibitors on mechanical, thermal and carrageenan-induced nociception in male mice.

EXPERIMENTAL APPROACH

We used single and repeated administration of a peripherally restricted, short-acting (nitecapone) and also a centrally acting (3,5-dinitrocatechol, OR-486) COMT inhibitor. We also tested CGP 28014, an indirect inhibitor of COMT enzyme. Effects of OR-486 on thermal nociception were also studied in COMT deficient mice. Effects on spinal pathways were assessed in rats given intrathecal nitecapone.

KEY RESULTS

After single administration, both nitecapone and OR-486 reduced mechanical nociceptive thresholds and thermal nociceptive latencies (hot plate test) at 2 and 3 h, regardless of their brain penetration. These effects were still present after chronic treatment with COMT inhibitors for 5 days. Intraplantar injection of carrageenan reduced nociceptive latencies and both COMT inhibitors potentiated this reduction without modifying inflammation. CGP 28014 shortened paw flick latencies. OR-486 did not modify hot plate times in Comt gene deficient mice. Intrathecal nitecapone modified neither thermal nor mechanical nociception.

CONCLUSIONS AND IMPLICATIONS

Pro-nociceptive effects of COMT inhibitors were confirmed. The pro-nociceptive effects were primarily mediated via mechanisms acting outside the brain and spinal cord. COMT protein was required for these actions.     

Simple anthropometric measures identify fasting hyperinsulinemia and clustering of cardiovascular risk factors in Asian Indian adolescents

Correlations of easily measurable parameters of obesity (body mass index [BMI], waist circumference [WC], and subscapular skinfold thickness) with fasting hyperinsulinemia and cardiovascular risk factors (CRFs) have not been investigated in adolescents. We evaluated the screening performance of 3 anthropometric measurements, BMI, WC, and subscapular skinfold thickness, in identifying fasting hyperinsulinemia and clustering of CRFs in 680 male and 521 female adolescents and young adults aged 14 to 18 years in a cross-sectional population survey. CRFs considered were hypercholesterolemia, hypertriglyceridemia, low levels of high-density lipoprotein cholesterol, impaired fasting blood glucose, hypertension, and fasting hyperinsulinemia. The ability of the anthropometric measurements to identify the clustering of CRFs without (cluster 1) and with fasting hyperinsulinemia (cluster 2), and fasting hyperinsulinemia alone was evaluated. BMI, WC, and subscapular skinfold thickness identified the clustering of CRFs and fasting hyperinsulinemia better in males than in females. Among individual risk factors, WC was better in identifying the presence of 3 or more risk factors in cluster 1 for both males and females, and in cluster 2 in females. Subscapular skinfold thickness was better than BMI and WC in identifying hyperinsulinemia in males, and the presence of 3 or more risk factors in cluster 2 in females. All 3 measurements were more accurate in identifying fasting hyperinsulinemia than presence of 3 or more CRFs in either cluster 1 or cluster 2 with higher odds ratio for males. This study shows gender differences in identification of insulin resistance and clustering of CRFs by using simple anthropometric parameters in Asian Indian adolescents. These simple measurements are useful for preventing and predicting cardiovascular risk and for generating a correct definition of the metabolic syndrome.     

Rapid diagnosis and tumor margin assessment during pancreatic cancer surgery with the MasSpec Pen technology

Intraoperative delineation of tumor margins is critical for effective pancreatic cancer surgery. Yet, intraoperative frozen section analysis of tumor margins is a time-consuming and often challenging procedure that can yield confounding results due to histologic heterogeneity and tissue-processing artifacts. We have previously described the development of the MasSpec Pen technology as a handheld mass spectrometry–based device for nondestructive tissue analysis. Here, we evaluated the usefulness of the MasSpec Pen for intraoperative diagnosis of pancreatic ductal adenocarcinoma based on alterations in the metabolite and lipid profiles in in vivo and ex vivo tissues. We used the MasSpec Pen to analyze 157 banked human tissues, including pancreatic ductal adenocarcinoma, pancreatic, and bile duct tissues. Classification models generated from the molecular data yielded an overall agreement with pathology of 91.5%, sensitivity of 95.5%, and specificity of 89.7% for discriminating normal pancreas from cancer. We built a second classifier to distinguish bile duct from pancreatic cancer, achieving an overall accuracy of 95%, sensitivity of 92%, and specificity of 100%. We then translated the MasSpec Pen to the operative room and predicted on in vivo and ex vivo data acquired during 18 pancreatic surgeries, achieving 93.8% overall agreement with final postoperative pathology reports. Notably, when integrating banked tissue data with intraoperative data, an improved agreement of 100% was achieved. The result obtained demonstrate that the MasSpec Pen provides high predictive performance for tissue diagnosis and compatibility for intraoperative use, suggesting that the technology may be useful to guide surgical decision-making during pancreatic cancer surgeries.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer, with a 5-y survival rate of 9% for all stages (1). Among patients with resectable tumors, surgical resection with microscopically negative margins is required for prolonged disease-free survival (2). Thus, differentiating normal tissue from tumor is the cornerstone of effective pancreatic oncologic surgery (3, 4). In practice, delineation of pancreatic resection margins is difficult and variable. Tumor margin status is commonly assessed intraoperatively by microscopic histopathological evaluation of frozen sections prepared from excised pancreatic neck and common bile duct margins prior to completion of the operation (5, 6). However, artifacts on tissue histology from frozen section preparation complicates histopathologic evaluation, further accentuated by the complex pathology of PDAC, with high desmoplastic stromal content and chronic pancreatitis (CP) at the pancreatic resection margins as well as inflammation induced by surgical manipulation of bile duct tissue–mimicking tumor (7, 8). Moreover, the reported accuracy of frozen section analysis is variable center-to-center and depends on the methodology, skillset, and subspecialty of the pathologist on call (9–12).Several optical and molecular technologies are being developed with the expectation of improving pancreatic cancer detection during surgery (SI Appendix, Text) (13–15). In particular, mass spectrometry (MS) technologies are powerful for investigating molecular differences between normal and cancerous tissues with high sensitivity, chemical specificity, and speed and have also been explored for surgical use and margin evaluation (16). Desorption electrospray ionization (DESI) MS, for example, has been used to investigate molecular differences between normal and cancerous tissues ex vivo cancerous and normal tissue sections (17–19). In particular, Zare and coworkers applied DESI-MS imaging to analyze the metabolic and lipid profiles of adjacent histologic tissue sections of margin regions collected from pancreatic surgery (20). Other techniques (i.e., rapid evaporative ionization MS and laser-based MS devices) have been developed for in vivo cancer detection (21–24). However, these techniques have not yet been demonstrated for pancreatic cancer tissue detection.We developed the MasSpec Pen system as a biocompatible handheld device coupled to a mass spectrometer for rapid (∼15 s) and nondestructive tissue analysis (25). Upon contact with a tissue and activation by a foot pedal, a discrete water droplet is formed and contained at the MasSpec Pen tip reservoir, allowing metabolites and lipids to be gently extracted into the water droplet, which is then transported to the mass spectrometer for analysis. To date, we have applied the MasSpec Pen in conjunction with least absolute shrinkage and selector operator (Lasso) penalized logistic regression to classify several tumor types ex vivo, achieving 96% overall accuracy in cross-validation (CV) (25–27). More recently, we translated the MasSpec Pen technology to an operating room (OR) to evaluate technical feasibility in open human surgeries and as a laparoscopic device in a robotic surgical procedure (28, 29).Here, we describe the application and first use of the MasSpec Pen for the acquisition and statistical prediction of molecular data acquired from pancreatic and biliary tissues, including in vivo data of surgical margins collected in an OR from patients undergoing pancreatic surgery. Collectively, our results indicate that the MasSpec Pen technology may be useful to enhance surgical margin evaluation in pancreatic cancer procedures by providing near–real-time diagnostic feedback to surgeons and physicians.     

Intracranial pressure monitors in traumatic brain injury: a systematic review

We conducted a systematic review to examine the relationship between intracranial pressure monitors (ICP) monitors and mortality in traumatic brain injury (TBI). We systematically searched for articles that met the following criteria: (1) adults patients, (2) TBI, (3) use of an ICP monitor, (4) point estimate for mortality with ICP monitoring (5) adjustment for potential confounders. Six observational studies were identified with 11,371 patients. There was marked between-study heterogeneity that precluded a pooled analysis. Patients with ICP monitors had different clinical characteristics and received more ICP targeted therapy in the ICU. Four studies found no significant relationship between ICP monitoring and survival, while the other two studies demonstrated conflicting results. Significant confounding by indication in observational studies limits the examination of isolated TBI interventions. More research should focus on interventions that affect TBI careplan systems. Further research is needed to identify which subset of severe TBI patients may benefit from ICP monitoring.     

Effects of short birth spacing on birth-order differences in child stunting: Evidence from India

Do firstborn children have a height advantage? Empirical findings have found mostly that, yes, second or higher-order children often lag behind firstborns in height outcomes, especially in developing countries. However, empirical investigations of birth-order effects on child height overlook the potential impact that birth spacing can have. We provide an explanation for the negative birth-order effect on stunting outcomes for young Indian children and show it is driven by short preceding-birth spacing. We find that firstborn children are taller than children of higher birth order: The height-for-age gap for third (or higher)-order children is twice the gap for children second in birth order. However, this pattern is observed when spacing between later-born children and their immediate elder siblings is fewer than 3 y. Interestingly, the firstborn height advantage disappears when later-born children are born at least 3 y after their elder siblings. Thus, our findings indicate that spacing length between children explains differences in height, over birth order. Although India’s family planning policy has resulted in a substantial reduction in total fertility, its achievement in spacing subsequent births has been less impressive. In showing that spacing can alleviate or aggravate birth-order effects on attained height, our study fills an evidence gap: Reducing fertility alone may not be sufficient in overcoming negative birth-order effects. To reduce the detrimental effects of birth order on child stunting, policy responses—and therefore research priorities—require a stronger focus on increasing the time period between births.

Child undernutrition continues to be a problem in low-and middle-income countries, and adversely affects child survival and well being (1). While child undernutrition is gauged by several indicators, stunting—a key marker of chronic undernutrition obtained by comparing child height with that of children in the same age group in a healthy reference population—is at the forefront of discussion because of its vast prevalence across all developing regions and its important consequences for health and development. Almost all of stunting takes place in the first 1,000 d from conception to 2 y of age, but its consequences follow throughout adulthood. These consequences are largely irreversible, making stunting an extremely critical condition (2, 3). Children who are stunted are vulnerable to disease and mortality during childhood and run a much higher risk of developing deficits in later-life outcomes, including in adult height, cognitive and intellectual ability, and as a consequence, on schooling attainment, productivity, and earnings (4–10). Furthermore, if stunting is accompanied by excessive weight gain later in childhood, there is an increased risk of developing adult obesity and nutrition-related chronic diseases, including cardiovascular disease, stroke, and type 2 diabetes in adult life (see, for example, ref. 6). In addition, stunted girls carry additional risk of having adverse pregnancy outcomes and reproductive complications as adults, leading to detrimental intergenerational effects (11, 12). Nevertheless, stunting is preventable, and reducing it is an important component of overall development for the well being of children.In recognition of the high social and economic costs of stunting, efforts are ongoing to address this public health issue, including programs aimed at reducing poverty and inequality, improving dietary intake and access to healthcare services, and improving the hygiene environment. Childhood stunting has declined by 35% from a global estimate of 253 million in 1990, with over 90 million children protected from suboptimal growth and a large number of child deaths prevented. However, this decrease is small relative to the overall burden, as over 161 million children under 5 y were reported to be stunted in 2011 (13). Furthermore, there is a large disparity in numbers across regions, with the highest number of over 69 million stunted children living in South Asia and with India bearing 90% of this regional burden (14). Thus, although stunting levels have been reduced, the progress has been both uneven and suboptimal (15). There is need to develop strategies, policies, and programs tailored to local conditions, which in turn require a case-by-case approach to identify what other conditions may be predisposing children to poor height in certain regions, and also, within regions.Birth order—an indicator of a child’s position in the age hierarchy of siblings—has been used time and again to explain variation in height outcomes in children. Children born to the same parents share the same genetic make-up; yet, the order in which they are born exposes them to different biological and behavioral environments (16, 17). Through differences in health endowments and parental investments, birth order often affects the health and nutritional outcomes of children. Hence, birth-order effects reflect differences in the unshared environment within a family. The literature on child stunting has provided significant evidence from across countries that children of lower birth order are at an advantage, compared to children of higher birth order. Firstborn children are taller compared to those born subsequently, and this height advantage increases sharply over the higher order of birth of siblings. Explanations for the firstborn height advantage have addressed issues, such as better health endowments of the firstborn at birth and parental favoritism toward some offspring over others—usually the eldest son—generating more prenatal and postnatal investments, greater time investment in child care, longer duration of breastfeeding, and also affecting the desire for having more children (18–24).However, an important factor in assessing the birth-order effects on child health and nutritional outcomes is the length of interval between two consecutive births: That is, birth spacing. A wealth of studies have shown that a short length of birth spacing is associated with higher risk of maternal mortality and adverse subsequent birth outcomes, such as child mortality, preterm birth, small for gestational age, and low birthweight, though the degree to which the relationship holds varies substantially across countries (25–29). These associations stem from the biological factor commonly referred to as maternal depletion syndrome (26, 30). Closely spaced pregnancies may not allow sufficient time for the mother to restore her depleted micronutrient and macronutrient stores from the previous birthing, which in turn may reduce her ability to provide a favorable fetal growth environment in subsequent pregnancies and sufficient breast milk production postdelivery. Literature also suggests short birth spacing is associated with suboptimal parental care practices, which adversely affect the health and nutritional outcomes of siblings born close to each other. For example, the birth of a new baby may reduce the parental care time devoted to older siblings, as well as result in poor postnatal investment; similarly, a new pregnancy may reduce or curtail breast milk production, which may lead to suboptimal feeding for older siblings.While the aforementioned channels show the potential for longer birth spacing to influence nutritional outcomes of children more positively, especially for the later born, empirical inquiry into the spacing order linkages is limited. We believe that birth order and height linkage can be better understood by examining the interaction between birth order and birth spacing. Using an illustrative example of India in this paper, we demonstrate that the negative association between increasing birth order and child height is driven by the short length of interval between births. We link height-for-age standardized scores (HAZ) of children under 5 y, recorded in the latest Indian Demographic and Health Survey (DHS), to an indicator of birth order, disaggregated by the length of preceding birth spacing. When birth order is considered alone, we find that firstborn children on average are taller than children of higher birth order. This result is consistent with previous research on birth order. However, we discover noteworthy changes in the patterns of the HAZ gap between firstborn and subsequent children on combining birth order with preceding birth spacing. We find that the firstborn height advantage is significant if birth spacing between the higher-order child and its immediate elder sibling is less than 3 y, and this advantage gets steeper with increasing order of birth; that is, the height advantage for firstborns, compared to children from third or higher-order births, is almost twice the height advantage for firstborns, compared to children of second-birth order. Interestingly, if the birth spacing between the higher birth-order child and its immediate elder sibling is 3 or more years, the firstborn height advantage disappears and becomes insignificant. This is true with respect to the gap for all higher birth-order children. Thus, higher birth-order children, on average, are as tall as firstborn children if they are appropriately spaced. Our results emphasize the importance of time between births in determining height outcomes of young children, over birth order, and demonstrate how spacing length may weaken or strengthen the birth-order effect on child height. Designing and implementing policies and interventions that affect knowledge and attitude toward healthy spacing could significantly impact the health, nutrition, and accomplishments of young children.However, we emphasize at the outset that our analysis is exploratory in nature. An ideal dataset for comparing height outcomes across birth orders would require longitudinal data, recording all pregnancies conceived by a woman with predelivery and postdelivery information related to healthcare, as well as feeding practices for every living child. Because of the absence of datasets that cover all these aspects, we rely on DHS data, which are closely but imperfectly suited to the question at hand. The nature of DHS is such that anthropometry is recorded only for children below 5 y, and for many healthcare and dietary intake variables the information is collected only for the youngest child born to the mother. Hence, the reduced sample size and data limitations preclude our ability to establish causality. However, the large sample size is sufficient to assess subgroup and interaction effects. We address several possible biases or limitations of using survey data with additional analyses.