Mouhanad Hammami - Academia.edu (original) (raw)

Papers by Mouhanad Hammami

Pediatric Research, 1997

There is no systematic determination on the relationship of biochemical bone turnover markers (BT... more There is no systematic determination on the relationship of biochemical bone turnover markers (BTO) and calciotropic hormones in human newborns. Cord blood was obtained from 60 newborns with birth weights 1769-3970 g and GA 33-41 wks. Cord values of BTO by immunoassay: ...

E-spen, The European E-journal of Clinical Nutrition and Metabolism, 2011

Background & aims: Total body dual energy X-ray absorptiometry (DXA) is a useful non-invasive tec... more Background & aims: Total body dual energy X-ray absorptiometry (DXA) is a useful non-invasive technique in the assessment for bone and soft tissue growth and development in infants although the role of regional DXA measurements is not well defined. Methods: Regional measurements including extremities, trunk and head were obtained by software delineation from a database of infant whole body DXA scans based on pencil beam (PB) and fan beam (FB) DXA techniques. Results: Data from fan beam or pencil beam were similar. All regional DXA measurements were correlated and predictive of total body measurements. The relationship to total body measurements was better for larger regions such as the trunk and lower extremities, and for lean, fat, bone mineral content, fat and fat percent (adjusted r 2 0.78 to 0.98 for FB and 0.82 to 1.00 for PB). At the head region, bone mineral density was best related to total body measurements with adjusted r 2 > 0.92 for both DXA techniques. DXA measurements from left and right extremities were correlated but the agreement varied among different DXA parameters. Weight was the best predictor for regional as well as total body bone and soft tissue measurements although other physiologic predictors including length, age, gender and race could be forced into prediction equation. Conclusions: Regional DXA measurements may be considered as a screening tool to monitor changes in bone and soft tissue composition during infancy but they should not be used as a surrogate replacing total body measurements.

Objective: To study the relationship between anthropometric measurements and living conditions in... more Objective: To study the relationship between anthropometric measurements and living conditions in infants and children living in refugee camps.

Journal of Clinical Densitometry, 2001

There are no data on the relative accuracy and precision of regional bone mass measurement from w... more There are no data on the relative accuracy and precision of regional bone mass measurement from whole-body dual energy X-ray absorptiometry (DXA) scans in small young subjects. Twelve domestic swine piglets (2550-17,660 g) were scanned on a single-beam and on a fan beam densitometer using each humerus and femur as the region of interest to determine the validity of five different scan modes: two infant whole body (IWB), two spine, and one rat whole body (RWB) scan mode in the determination of regional bone mass measurements. DXA bone mineral content (BMC( measurements from RWB and IWB fan beam and IWB single-beam scans were highly predictive of ash weight (adjusted r2 = 0.98, 0.94, 0.94, respectively). Correlation between left and right limbs was highly significant (p < 0.001 for all comparisons) for ash weight (r = 0.99) and for DXA measurements of BMC (r = 0.92-0.99), area (r = 0.92-0.99), and bone mineral density (r = 0.87-0.99) for all modes of DXA scan. Repeatability (as standard deviation of differences of repeated scans) varied with scan mode and DXA parameters and ranged from 1.5 to 7.6%and from 1.8 to 14.7% for intra-and interoperator, respectively. We conclude that regional DXA measurements from IWB and RWB scans can be assessed accurately and with adequate precision for clinical use in subjects with low bone mass comparable with infants and young children. The RWB scan is useful for research studies. However, appropriate training and documentation of precision errors is needed to minimize repeatability errors.

Pediatrics, 2003

Palm and palm olein (PO) oils are used in some infant formula fat blends to match the fatty acid ... more Palm and palm olein (PO) oils are used in some infant formula fat blends to match the fatty acid profile of human milk, but their presence has been shown to lower calcium and fat absorption. We aimed to determine if the reported differences in calcium absorption could affect skeletal development by comparing bone mineral accretion in healthy term infants fed a milk-based formula with (PMF) or without PO. Whole body bone mineralization was evaluated in healthy term infants fed 1 of 2 coded, commercially available, ready-to-feed infant formulas in a randomized, double-blind, parallel study. Subjects were fed either 1). PMF formula (Enfamil with iron; Mead Johnson Division of Bristol Myers, Evansville, IN; N = 63) containing PO/coconut/soy/high-oleic sunflower oils (45/20/20/15% oil); or 2). milk-based formula without PO (Similac with iron; Ross Products Division Abbott Laboratories, Columbus, OH; N = 65), containing high-oleic safflower/coconut/soy oils (40/30/30% oil) from enrollment by 2 weeks after birth until 6 months. Anthropometrics and formula intake were determined monthly; total body bone mineral content (BMC) and bone mineral density (BMD) were measured at baseline, 3, and 6 months of age using dual energy x-ray absorptiometry. Intent-to-treat analyses indicated no significant differences between feeding groups in weight, length, head circumference, or formula intake throughout the study. BMC and BMD were not different at baseline but repeated measures analyses show that infants fed PMF had significantly lower BMC and BMD at 3 and 6 months. Healthy term infants fed a formula containing PO as the predominant oil in the fat blend had significantly lower BMC and BMD than those fed a formula without PO. The inclusion of PO in infant formula at levels needed to provide a fatty acid profile similar to that of human milk leads to lower bone mineralization.

Journal of Clinical Densitometry, 2011

Journal of Pediatrics, 2001

The objective was to compare dual-energy x-ray absorptiometrymeasured body composition between la... more The objective was to compare dual-energy x-ray absorptiometrymeasured body composition between large (LGA) and appropriate (AGA) birth weight for gestational age neonates.

Calcified Tissue International, 2001

This study aims to test the hypothesis that non invasive bone mass measurements can be used to pr... more This study aims to test the hypothesis that non invasive bone mass measurements can be used to predict bone strength in a piglet model. Dual energy X-ray absorptiometry measurements of bone mineral content (BMC), bone mineral density (BMD), and bone area (BA) were obtained from four sets of bones (left and right humeri and femora) of 12 piglets (6-68 days and 2250-17660 g). Bone strength, defined by the energy to bone failure, fracture moment, and flexural rigidity, was determined from three point bending tests using an Instron material testing system. Results show that bone mass between left and right extremities was highly correlated (r ‫ס‬ 0.96 to 0.99, P Յ 0.001 all comparisons) and was similar for bone strength (r ‫ס‬ 0.85 to 0.98, P < 0.01 all comparisons). However, based on the standard deviation of the difference between measurements from left and right extremities, the agreement between sides was better for bone mass than for bone strength measurements. For each set of bones, bone mass measurements were highly correlated with bone strength measurements (r ‫ס‬ 0.68-0.99, P < 0.05-Յ0.001). The predictive ability of bone mass on bone strength varied (adjusted r 2 ‫ס‬ 0.41-0.97) depending on the bone tested and the measurement parameter used, although remained statistically significant in all instances (P < 0.05-Յ0.001). We conclude that in developing organisms, noninvasive bone mass measurements are correlated with and predictive of bone strength, although bones from the same side and same anatomical site should be used for comparison purposes.

Pediatric Research, 2010

Bone quantitative ultrasound generated speed of sound (SOS) is a marker of bone strength. However... more Bone quantitative ultrasound generated speed of sound (SOS) is a marker of bone strength. However, critical evaluation of its validity for use in small bones is extremely limited, and SOS data may not be consistent with data obtained from dual energy ϫ ray absorptiometry, another marker of bone strength. We report the SOS values pre and postinjection of s.c. fat using a chicken bone model; and in large for gestation and appropriate for gestation neonates to determine the influence of s.c. fat. Average SOS were lowered for the chicken bones postfat injection by 36 m/s (CS probe) and 58 m/s (CR probe), and in large for gestation group by 75 m/s (CS probe) and 51 m/s (CR probe) (p ϭ 0.03-0.004 paired t test) although SOS measurements from each probe are significantly correlated within the large (r ϭ 0.78) and appropriate (r ϭ 0.83) for gestation group. Failed SOS measurements occurred significantly more frequently in the postinjection studies regardless of the probe used in the chicken bone model and for the CS probe in large for gestation neonates. The lowered bone quantitative ultrasound measurements in large for gestation neonates is likely a measurement artifact from increased s.c. fat. Abbreviations: AGA, appropriate birth weight for gestation; DXA, dual energy X ray absorptiometry; LGA, large for gestation; QUS, quantitative ultrasound; SOS, speed of sound

Pediatric Radiology, 2008

Background Factors that affect quantitative ultrasound (QUS) bone measurements have not been clea... more Background Factors that affect quantitative ultrasound (QUS) bone measurements have not been clearly defined for all clinical populations. Objective To determine some technical and clinical aspects that may affect QUS bone measurement in the neonate–maternal dyad. Materials and methods Speed of sound (SOS) was measured at the radius and tibia using a commercial multisite axial transmission QUS instrument and three manufacturer-provided probes (CS, CR and CM). Results The study included 183 singleton neonates and 159 mothers. The type of probe, weight and edema significantly affected SOS measurements. In infants, the CS and CR probes measured SOS consistently at the tibia but not the radius. Gestational age was predictive of SOS from the CS probe and remained significant when race, gender, and birth weight were included. None of these parameters predicted SOS when using the CR probe. Maternal SOS at the radius and tibia was correlated with the CM probe. Maternal SOS was predicted by age but not by gravid status, number of living children, or race. There was no consistent correlation between maternal–infant dyad SOS measurements. Conclusions Axial transmission SOS of bone varies with probe and site and is affected by technical and clinical factors. Valid data depend on documentation of the probes used and the clinical population studied.

A piglet model was used to determine whether the fan beam dual energy X-ray absorptiometry techni... more A piglet model was used to determine whether the fan beam dual energy X-ray absorptiometry technique (DXA) could be adapted for the measurement of body composition of small subjects. Commercial domestic swine piglets (n ‫؍‬ 14) with weights between 1.95 and 21.1 kg had duplicate fan beam-DXA scans followed by chemical analysis of body composition. Each scan required 2-3 min to complete. DXA-measured total body weight was validated against scale weights of the piglets (with and without blanket and other covering), DXA bone mineral content validated against carcass ash and calcium, and DXA lean and fat mass validated against chemical lean and fat contents. Measurements from duplicate DXA scans were highly reproducible with adjusted r 2 values from 0.992 to 1.000. Each DXA measurement was highly predictive of the scale weight or specific chemical body composition with adjusted r 2 values from 0.974 to 0.999. The intraclass reliability coefficient among measurements from individual scans with scale weight or the weight of individual chemical components was extremely high at ≥0.99 for all comparisons. The SD of residuals for DXA prediction of scale weights (with and without covering) were 168 and 157 g, respectively, and were 27, 8.8, 122 and 72 g for the prediction of carcass ash, calcium, lean and fat tissue content, respectively. We conclude that rapid scan acquisition, accurate and precise prediction of scale weight and components of body composition would support the use of fan beam-DXA for body composition studies in growing humans or animals. J. Nutr. 132: 1380 -1383, 2002.

Journal of Clinical Densitometry, 1998

The aim of this study was to determine in healthy sedentary subjects the effect of hand dominance... more The aim of this study was to determine in healthy sedentary subjects the effect of hand dominance on side-to-side difference in bone area and bone mass for upper and lower extremities. Dual-energy X-ray absorptiometry (DXA) measurements of both forearms and hips were performed on 193 right-handed and 20 left-handed subjects as determined by self-report. Scan acquisition and scan analyses were performed by one investigator, but all scan pairs were independently assessed for symmetry of positioning and movement artifacts by three investigators. Results show that DXA measurements between sides may be highly correlated regardless of the symmetry of the scan pair. However, asymmetric DXA scan pairs may have more than twice the side-to-side difference found in symmetric DXA scan pairs at the hip. Side-to-side differences between subregions were greater than the differences between measurements at the total radius, ulna, or hip. For symmetric pairs of DXA scans, the dominant forearm has significantly higher bone area and bone mineral content (BMC). Bone mineral density (BMD) was significantly higher only in the ulna of the dominant forearm. However, the nondominant forearm has higher values than dominant forearm in at least one DXA measurement in >24% of the subjects. There were no significant differences in any DXA measurements between hips, and higher DXA measurements did not occur significantly more frequently at the hip corresponding to the dominant hand. We conclude that healthy sedentary subjects tend to have proportionally higher bone area and BMC in the dominant forearm that results in similar BMD between dominant and nondominant forearms. This relationship does not appear to be applicable to measurements at the hip. In addition, there is a significant proportion of subjects with higher bone area and BMC in the nondominant extremities. Thus, in sedentary subjects, the consistency in the use of same extremity and the consistency in scan acquisition techniques and scan analyses is of greater importance than the selection of an extremity based on hand dominance in DXA studies.

Background: Compared with the older pencil-beam (PB) dualenergy X-ray absorptiometry (DXA), the n... more Background: Compared with the older pencil-beam (PB) dualenergy X-ray absorptiometry (DXA), the newer fan-beam (FB) DXA has the advantage of faster scan acquisition and greater accuracy of body-composition measurement in small subjects. However, no data exist on the relation between the measurements obtained with these techniques. Objective: The objective of the study was to investigate whether PB and FB DXA measurements in small subjects are interchangeable. Design: PB and FB DXA scans were performed on 26 piglets and 54 infants to examine the relation between the measurements obtained by using the 2 techniques. Results: The correlation between all PB and FB DXA measurements of variables (total weight, bone area, bone mineral content, bone mineral density, and lean and fat masses) approached 1.0, but there were significant differences in absolute values. The extent of the differences varied according to the variable, with the lowest value for total weight (mean difference: Ϸ1% for both piglets and infants) and the highest value for bone mineral content (mean difference: 35.3% and 36.7% for piglets and infants, respectively). PB and FB DXA measurements were strongly predictive of each other after adjustment (r 2 = 0.927-1.000 for the piglet data and 0.939-0.999 for the infant data). Conclusion: In small subjects, DXA measurements from PB and FB techniques were strongly predictive of each other, although their absolute values differed. Thus, group comparison of PB and FB DXA data is possible after adjustment of the data from either technique. It is advisable to generate normative data for each technique and to use the same technique throughout longitudinal studies.

Journal of Clinical Densitometry, 2002

Dual X-ray absorptiometry (DXA) is generally regarded as the best technique for determining bone ... more Dual X-ray absorptiometry (DXA) is generally regarded as the best technique for determining bone mass in small subjects (1). Commercial softwares for bone mass measurement of the whole body (2-5) and spine (6) in infants have been validated for scan acquisition and analyses using DXA instruments that generate alternating distinct high-and low-energy X-rays.

Nutrition Journal, 2007

Background Leptin and its soluble receptor (sOB-R) are important to regulation of body compositio... more Background Leptin and its soluble receptor (sOB-R) are important to regulation of body composition but there are no data on the developmental variations in these plasma variables and their relationship with body composition measurements, Methods Weight, length, and body composition (bone, fat and lean mass) by dual energy absorptiometry, and plasma variables were measured in healthy infants at 2, 4, 8 and 12 months. Results 15 whites and 29 African Americans (21 males and 23 females) with mean birth weight 3357 +/- 45 (SEM) g and gestation of 39.3 +/- 0.17 weeks were studied. The overall Z score for weight, length and weight for length during the study were 0.00 +/- 0.15, -0.08 +/- 0.11 and 0.12 +/- 0.14 respectively. With increasing age, plasma leptin (1.0 to 18.2, median 5.5 ng/mL) and sOB-R:leptin molar ratio (10.1 to 247.4, median 59.9) were lowered (r = -0.47, p < 0.01; and r = -0.37, p < 0.05 respectively), best predicted by weight Z score and percentage of fat mass, and higher in African American and female. Presence of body composition measurements eliminated the race and gender effect on the plasma variables. Plasma sOB-R (49.5 to 173.9, median 81.3 ng/mL) did not change significantly with age and was correlated and predicted only by body composition measurements. Conclusion In healthy growing infants, plasma leptin but not sOB-R decreases with age. Gender, race and anthropometric measurements are additional physiological determinants predictive of plasma leptin and the receptor:ligand ratio. However, body composition is the only variable that can predict plasma leptin and its soluble receptor and the receptor: ligand ratio; and body composition measurements eliminated the race and gender effect on these plasma variables.