Jean Wade

Bone Turnover and Growth During and After Continuing Chemotherapy in Children with Acute Lymphoblastic Leukemia

Children treated for acute lymphoblastic leukemia may develop reduced bone mineral density during treatment, but there is little information on the mechanisms involved. In a prospective, longitudinal study on 15 children with ALL, we undertook serial measurements of markers of bone and collagen turnover, insulin-like growth factor (IGF)-I and its binding proteins (IGFBPs)-3 and -2 during the second year of continuing chemotherapy. In eight patients we also measured lower leg length by knemometry. Height SD scores, lower leg length velocity, IGF-I, and markers of bone collagen turnover did not differ significantly from healthy children. However, bone alkaline phosphatase, a marker of the differentiated osteoblast, was lower (mean SD score, −0.64;p < 0.0001), whereas procollagen type III N-terminal propeptide (P3NP, a marker of soft tissue collagen turnover; mean SD score, +0.93, p < 0.05), IGFBP-3 (mean SD score, +0.76;p < 0.01), and IGFBP-2 (mean SD score, +1.24, p = 0.01) were all higher than in healthy children. IGFBP-3 decreased during episodes of afebrile neutropenia (p < 0.05). Within 3 mo after completion of treatment, bone ALP increased in all eight patients, but collagen markers showed little change. IGFBP-2 returned to normal posttreatment, but P3NP and IGFBP-3 remained significantly elevated compared with healthy children (mean SD scores, +1.51 and +1.36, respectively;p < 0.01). We conclude that continuing chemotherapy was associated with normal growth and bone collagen turnover but enhanced soft tissue collagen turnover. Bone bone alkaline phosphatase was low throughout treatment, which suggests impaired osteoblast differentiation resulting from a direct effect of chemotherapy on bone. Although the effect was reversible, the long-term implications for bone health in survivors remain uncertain.

Bone and collagen markers in preterm infants: relationship with growth and bone mineral content over the first 10 weeks of life.

In a longitudinal study of 25 preterm infants, we have examined the relationship of bone-specific alkaline phosphatase (ALP), C-terminal propeptide of type I collagen (PICP), N-terminal propeptide of type III procollagen (P3NP), C-terminal telopeptide of type I collagen, urinary pyridinoline (Pyd) and deoxypyridinoline (Dpd), with rates of gain in weight, length, and lower leg length and with bone mineral content (BMC), all measured at weekly intervals over the first 10 wk of life. Concentrations of all collagen markers were 10-fold higher than in older children. Each marker showed a distinctive pattern of postnatal change, with early increases in PICP and P3NP and decreases in ICTP reflecting postnatal growth. Once markers had reached a plateau during weeks 4–10, P3NP was positively correlated, whereas Pyd and Dpd were negatively correlated with rate of weight gain (r= +0.44, −0.46, and −0.40, respectively, p< 0.05). P3NP was also positively correlated with overall linear growth (r= +0.44, p< 0.05). PICP was strongly correlated with mean BMC (r= +0.63, p< 0.01) and with total BMC attained by the end of the study period (r= +0.81, p< 0.001). Bone ALP was positively correlated with the rate of bone mineral accretion (r= +0.55, p= 0.01). We conclude that the marker of soft-tissue collagen formation, P3NP, is a good marker for overall ponderal and linear growth in preterm infants, whereas the markers of collagen breakdown, Pyd and Dpd, have inverse relationships with weight gain. The osteoblast markers, PICP and bone ALP, seem to be good surrogate markers for bone mineralization in preterm infants. Markers may provide information on whole-body turnover of bone and collagen that is complementary to traditional physical measures of growth and bone mineralization.

Decidual Neutrophil Infiltration Is Not Required for Preterm Birth in a Mouse Model of Infection-Induced Preterm Labor

Parturition is associated with a leukocyte influx into the intrauterine tissues; however, the exact role these leukocytes play in the onset of labor remains unclear. Neutrophil infiltration of the uteroplacental tissues has been particularly associated with infection-associated preterm labor (PTL) in both women and mouse models. In this study, we investigated the role of neutrophils in a mouse model of infection-induced PTL. Intrauterine administration of LPS on day 17 of gestation resulted in a 7-fold increase in the number of decidual neutrophils compared with control mice receiving PBS (p < 0.01; n = 8–11). We hypothesized that neutrophil influx is necessary for PTL and that neutrophil depletion would abolish preterm birth. To test this hypothesis, mice were depleted of neutrophils by treatment with anti–Gr-1, anti–Ly-6G, or the appropriate IgG control Ab on day 16 of gestation prior to LPS on day 17 (n = 6–7). Successful neutrophil depletion was confirmed by flow cytometry and immunohistochemistry. Neutrophil depletion with Gr-1 resulted in reduced uterine and placental Il-1β expression (p < 0.05). Neutrophil depletion with Ly-6G reduced uterine Il-1β and Tnf-α expression (p < 0.05). However, neutrophil depletion with either Ab did not delay LPS-induced preterm birth. Collectively, these data show that decidual neutrophil infiltration is not essential for the induction of infection-induced PTL in the mouse, but that neutrophils contribute to the LPS-induced inflammatory response of the uteroplacental tissues.

Malnutrition, zinc supplementation and catch-up growth: changes in insulin-like growth factor I, its binding proteins, bone formation and collagen turnover

objective Zinc may be a limiting factor in restricting catch‐up growth in severely malnourished children. This study had two aims: (i) to examine the effect of different zinc supplementation regimens on IGF‐I, its binding proteins and on markers of bone and collagen turnover in severely malnourished children and (ii) to investigate mechanisms underlying catch‐up growth by examining changes in these markers during nutritional rehabilitation, their inter‐relationships and their relationships with ponderal and linear growth.

Effects of Dexamethasone Treatment on Bone and Collagen Turnover in Preterm Infants with Chronic Lung Disease

Dexamethasone is used commonly in the treatment of chronic lung disease of prematurity, but there are concerns about possible deleterious effects on growth and bone. Our aim in this study was to examine the effects of dexamethasone treatment on bone and collagen turnover in preterm infants. Bone-specific alkaline phosphatase, the C-terminal propeptide of type I collagen (PICP, reflecting whole-body type I collagen synthesis), and the N-terminal propeptide of type III procollagen (P3NP, reflecting soft tissue collagen turnover), together with the C-terminal telopeptide of type I collagen (ICTP), urinary pyridinoline (Pyd), and deoxypyridinoline (all markers of collagen breakdown) were measured at weekly intervals over the first 12 wk of life in 14 preterm infants with chronic lung disease treated with dexamethasone. Results were expressed as SD scores relative to preterm control infants not treated with dexamethasone. PICP, P3NP, ICTP, and Pyd all showed marked decreases (−2.1 to −3.7 SD scores) during the first week of treatment (p < 0.001), returning to pretreatment levels after stopping dexamethasone. In the group as a whole, these collagen markers were negatively correlated with dexamethasone dose (p < 0.0001); negative correlations were also seen in most individual babies, although the slopes of individual regression lines varied by a factor of 2. Weight gain at 12 wk was correlated with PICP, expressed as the mean SD score over 12 wk for each baby, (r = 0.69, p < 0.01) but not with other markers or cumulative dose of dexamethasone. We conclude that dexamethasone markedly suppressed collagen turnover in preterm infants in a dose-dependent fashion, although some babies were more affected than others. The degree of suppression of type I collagen synthesis was a strong independent predictor of overall weight gain over the first 12 wk of life.

Effects of a third intensification block of chemotherapy on bone and collagen turnover, insulin-like growth factor I, its binding proteins and short-term growth in children with acute lymphoblastic leukaemia

Children with acute lymphoblastic leukaemia (ALL) have reduced bone turnover caused by the disease itself and early intensive chemotherapy, but the effects of later chemotherapy using different drug combinations are uncertain. We report here a longitudinal study on 9 children with ALL randomised to receive an additional third intensification block of chemotherapy, compared with 9 children receiving continuing chemotherapy over the same period. During third intensification, bone alkaline phosphatase, procollagen type I C-terminal propeptide, the carboxyterminal propeptide of type I collagen, procollagen type III N-terminal propeptide and lower leg length all decreased in response to dexamethasone, then returned to (but not beyond) baseline levels after dexamethasone was stopped and other drugs started. These changes were unrelated to circulating insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 or IGFBP-2. In all children, bone alkaline phosphatase remained below the population mean throughout. We conclude that dexamethasone decreased bone and soft tissue turnover, probably through direct effects on target tissues. The postdexamethasone phase of third intensification and continuing chemotherapy had no major deleterious effect on collagen turnover, but there was evidence of continuing suboptimal bone mineralisation.

Complement inhibition and statins prevent fetal brain cortical abnormalities in a mouse model of preterm birth

Premature babies are particularly vulnerable to brain injury. In this study we focus on cortical brain damage associated with long-term cognitive, behavioral, attentional or socialization deficits in children born preterm. Using a mouse model of preterm birth (PTB), we demonstrated that complement component C5a contributes to fetal cortical brain injury. Disruption of cortical dendritic and axonal cytoarchitecture was observed in PTB-mice. Fetuses deficient in C5aR (-/-) did not show cortical brain damage. Treatment with antibody anti-C5, that prevents generation of C5a, also prevented cortical fetal brain injury in PTB-mice. C5a also showed a detrimental effect on fetal cortical neuron development and survival in vitro. Increased glutamate release was observed in cortical neurons in culture exposed to C5a. Blockade of C5aR prevented glutamate increase and restored neurons dendritic and axonal growth and survival. Similarly, increased glutamate levels - measured by (1)HMRS - were observed in vivo in PTB-fetuses compared to age-matched controls. The blockade of glutamate receptors prevented C5a-induced abnormal growth and increased cell death in isolated fetal cortical neurons. Simvastatin and pravastatin prevented cortical fetal brain developmental and metabolic abnormalities -in vivo and in vitro. Neuroprotective effects of statins were mediated by Akt/PKB signaling pathways. This study shows that complement activation plays a crucial role in cortical fetal brain injury in PTL and suggests that complement inhibitors and statins might be good therapeutic options to improve neonatal outcomes in preterm birth.

Biochemical Markers of Bone Turnover

Three studies to evaluate procollagen type I C-terminal propeptide, type I collagen cross-linked telopeptide and bone alkaline phosphatase (BALP) in the assessment of bone turnover and growth in children are presented. (1) In 50 short normal children treated with placebo or growth hormone, delta BALP after 3 months of treatment was highly correlated with height velocity response after 1 year (r = 0.67, p < 0.0001). (2) In 12 children with acute lymphoblastic leukaemia, marked changes in collagen peptides, BALP, and lower leg length velocity were seen during the first 6 months of chemotherapy. Suppression occurred during induction and the two intensification phases, with catch-up during the intervening phase (paired t-tests, p < 0.001). (3) Fourteen babies (birthweight < 1,500 g) treated with high-dose dexamethasone for bronchopulmonary dysplasia were compared with 25 non-steroid-treated babies < 1,500 g. Both collagen peptides decreased rapidly and dramatically (mean decreases 41-68%) after dexamethasone was started, accompanied by weight loss and lower leg shrinkage and followed by recovery during steroid weaning.

Myelin expression is altered in the brains of neonatal rats reared in a fluctuating oxygen atmosphere.

Background: Preterm infants receiving supplemental oxygen therapy experience frequent fluctuations in their blood oxygen levels, the magnitude of which has been associated with the incidence and severity of retinopathy of prematurity in such infants. Objective: Our objective was to investigate in a relevant animal model whether the immature brain with its poorly vascularised white matter might also be susceptible to injury when exposed to such fluctuations in blood oxygen. Methods: Newborn rats were reared in an atmosphere in which a computer reproduced the oxygen fluctuations derived from the transcutaneous oxygen levels of a 24-week preterm infant who had developed severe retinopathy. Following 14 days of exposure, we measured the expression of active caspase-3, myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) in the brains comparing with rat pups raised in room air. Results: Compared to room air controls, at day 14, the expression of active caspase-3 was increased by up to 162% (significant increase in 7 of 9 regions), MBP decreased by up to 70% (significant in the hypothalamus only) and GFAP increased by up to 103% (significant in 6 of 7 regions. On day 21, following 7 days of reparative recovery, GFAP levels in most areas of oxygen-exposed brains had returned to near control levels. There were no longer significant differences in caspase-3 levels apart from the cerebral cortex, cerebellum and striatum. In contrast, MBP expression was now much higher in most regions of the treated brains compared to controls. Conclusion: We conclude that fluctuations in blood oxygen, observed in preterm survivors, may constitute a source of injury to the white matter and corpus striatum of the developing brain and contribute to the neurological sequelae in extremely premature infants.

15-epi-lipoxin A4 reduces the mortality of prematurely born pups in a mouse model of infection-induced preterm birth

Preterm birth remains the leading cause of neonatal mortality and morbidity worldwide. There are currently few effective therapies and therefore an urgent need for novel treatments. Although there is much focus on trying to alter gestation of delivery, the primary aim of preterm birth prevention therapies should be to reduce prematurity related mortality and morbidity. Given the link between intrauterine infection and inflammation and preterm labour (PTL), we hypothesized that administration of lipoxins, key anti-inflammatory and pro-resolution mediators, could be a useful novel treatment for PTL. Using a mouse model of infection-induced PTL, we investigated whether 15-epi-lipoxin A4 could delay lipopolysaccharide (LPS)-induced PTL and reduce pup mortality. On D17 of gestation mice (n = 9–12) were pretreated with vehicle or 15-epi-lipoxin A4 prior to intrauterine administration of LPS or PBS. Although pretreatment with 15-epi-lipoxin A4 did not delay LPS-induced PTL, there was a significant reduction in the mortality amongst prematurely delivered pups (defined as delivery within 36 h of surgery) in mice treated with 15-epi-lipoxin A4 prior to LPS treatment, compared with those receiving LPS alone (P < 0.05). Quantitative real-time (QRT)-PCR analysis of utero-placental tissues harvested 6 h post-treatment demonstrated that 15-epi-lipoxin A4 treatment increased Ptgs2 expression in the uterus, placenta and fetal membranes (P < 0.05) and decreased 15-Hpgd expression (P < 0.05) in the placenta and uterus, suggesting that 15-epi-lipoxin A4 may regulate the local production and activity of prostaglandins. These data suggest that augmenting lipoxin levels could be a useful novel therapeutic option in the treatment of PTL, protecting the fetus from the adverse effects of infection-induced preterm birth.