New insights into factors influencing adult height in short SGA children: Results of a large multicentre growth hormone trial.

BACKGROUND: Growth hormone (GH) treatment is effective in improving adult height (AH) in short children born SGA. However, there is a wide variation in height gain, even after adjustment for predictive variables. It is therefore important to investigate new factors which can influence the response to GH. OBJECTIVE: To investigate the efficacy of GH treatment (1 mg/m(2/) day) in short SGA children on AH. To assess the relation between spontaneous catch-up growth after birth and growth during puberty on the total height gain SDS to AH. PATIENTS: Longitudinal GH trial in 170 children. RESULTS: Median age at start of GH was 7·1 years and height -3·0 SDS. AH was -1·8 SDS (TH-corrected AH -1·1 SDS) in boys and -1·9 SDS (TH-corrected AH -1·3 SDS) in girls. Spontaneous catch-up growth after birth was ≥0·5 SDS in 42% of children. In contrast to expectation, spontaneous catch-up growth was negatively correlated with total height gain SDS during GH (P = 0·009). During puberty, height SDS declined (-0·4 SDS in boys and -0·5 SDS in girls) resulting in a lower total height gain SDS than expected. Pubertal height gain was 25·5 cm in boys and 15·3 cm in girls, significantly lower compared to AGA children (P < 0·001). At onset of puberty, BA for boys and girls was moderately advanced (P = 0·02 and P < 0·001, respectively). Growth velocity was comparable to AGA children during the first two years of puberty, but thereafter significantly lower until reaching AH (P < 0·001). CONCLUSION: In contrast to our hypothesis, children with greater spontaneous catch-up growth after birth show a lower total height gain SDS during GH. Height SDS declines from mid-puberty, due to a marked early deceleration of growth velocity.

Rational design of enantioselective enzymes requires considerations of entropy.

Entropy was shown to play an equally important role as enthalpy for how enantioselectivity changes when redesigning an enzyme. By studying the temperature dependence of the enantiomeric ratio E of an enantioselective enzyme, its differential activation enthalpy (Delta(R-S)DeltaH(++)) and entropy (Delta(R-S)DeltaS(++)) components can be determined. This was done for the resolution of 3-methyl-2-butanol catalyzed by Candida antarctica lipase B and five variants with one or two point mutations. Delta(R-S)DeltaS(++) was in all cases equally significant as Delta(R-S)DeltaH(++) to E. One variant, T103G, displayed an increase in E, the others a decrease. The altered enantioselectivities of the variants were all related to simultaneous changes in Delta(R-S)DeltaH(++) and Delta(R-S)DeltaS(++). Although the changes in Delta(R-S)DeltaH(++) and Delta(R-S)DeltaS(++) were of a compensatory nature the compensation was not perfect, thereby allowing modifications of E. Both the W104H and the T103G variants displayed larger Delta(R-S)DeltaH(++) than wild type but exhibited a decrease or increase, respectively, in E due to their different relative increase in Delta(R-S)DeltaS(++).

Partial trisomy for 5q and monosomy for 12p in a liveborn child as a result of a complex five breakpoint chromosome rearrangement in a parent.

A balanced complex chromosome rearrangement (CCR) involving four chromosomes is very rare and may lead to different types of aneuploid germ cells. We report a liveborn child with multiple congenital anomalies and an apparently balanced translocation, t(11;12). High resolution chromosome analysis in the mother showed a CCR involving chromosomes 5, 11, 12, and 16. In situ hybridisation showed that this CCR was the result of a five break rearrangement, and that the derivative chromosome 12 consisted of parts of chromosomes 5, 11, and 12. From this it could be deduced that the karyotype of the child was not balanced, but resulted in partial trisomy for 5q and partial monosomy for 12p. The clinical findings in the child were compatible with partial trisomy for 5q.

Improved enantioselectivity of a lipase by rational protein engineering.

A model based on two different binding modes for alcohol enantiomers in the active site of a lipase allowed rational redesign of its enantioselectivity. 1-Halo-2-octanols were poorly resolved by Candida antarctica lipase B. Interactions between the substrates and the lipase were investigated with molecular modeling. Unfavorable interactions were found between the halogen moiety of the fast-reacting S enantiomer and a region situated at the bottom of the active site (stereoselectivity pocket). The lipase was virtually mutated in this region and energy contour maps of some variants displayed better interactions for the target substrates. Four selected variants of the lipase were produced and kinetic resolution experiments were undertaken with these mutants. Single point mutations gave rise to one variant with doubled enantioselectivity as well as one variant with annihilated enantioselectivity towards the target halohydrins. An increased volume of the stereoselectivity pocket caused a decrease in enantioselectivity, while changes in electrostatic potential increased enantioselectivity. The enantioselectivity of these new lipase variants towards other types of alcohols was also investigated. The changes in enantioselectivity caused by the mutations were well in agreement with the proposed model concerning the chiral recognition of alcohol enantiomers by this lipase.

Expression in Pichia pastoris of Candida antarctica lipase B and lipase B fused to a cellulose-binding domain.

Candida antarctica lipase B (CALB) and C. antarctica lipase B fused to a cellulose-binding domain (CBD-CALB) were expressed functionally in the methylotrophic yeast Pichia pastoris. The cellulose-binding domain originates from cellulase A of the anaerobic rumen fungus Neocallimastix patriciarum. The genes were fused to the alpha-factor secretion signal sequence of Saccharomyces cerevisiae and placed under the control of the alcohol oxidase gene (AOX1) promoter. The recombinant proteins were secreted into the culture medium reaching levels of approximately 25 mg/L. The proteins were purified using hydrophobic interaction chromatography and gel filtration with an overall yield of 69%. Results from endoglycosidase H digestion of the proteins showed that CALB and CBD-CALB were N-glycosylated. The specific hydrolytic activities of recombinant CALB and CBD-CALB were identical to that reported for CALB isolated from its native source. The fusion of the CBD to the lipase resulted in a greatly enhanced binding toward cellulose for CBD-CALB compared with that for CALB.

GH treatment and its effect on bone mineral density, bone maturation and growth in short children born small for gestational age: 3-year results of a randomized, controlled GH trial.

BACKGROUND: To investigate in a group of short children born small for gestational age (SGA), the effects of 3 years of GH treatment vs. no treatment on bone age (BA), height and bone mineral density (BMD). Also, to evaluate the influence of the severity of growth retardation at start and the GH dose on the gain in height. PATIENTS AND METHODS: The study design was an open-labelled, controlled multicentre GH study for 3 years. Non-GH-deficient (GHD) children (n = 87) were randomized to either a GH group (n = 61) or an untreated control group (n = 26). In addition, 12 SGA children had GHD (GHD group) and were treated in parallel. Both the GH and the GHD group were treated with a GH dose of 33 microg/kg/day. BMD was evaluated using dual energy X-ray absorptiometry (DEXA). In addition, data of our first GH trial in which short SGA children were treated with a GH dose of 66 microg/kg/day (n = 24) were used for comparison of height gain. RESULTS: In contrast to the control group, the GH group showed a significant increase in height (P < 0.001), as did the parallel GHD group. Bone maturation [delta bone age (BA)/delta calendar age (CA)] increased significantly during the first 2 years of GH treatment but slowed-down thereafter. The 3-year deltaBA/deltaCA ratio correlated significantly with the gain in height (r = 0.6, P < 0.001). At start, mean BMD SDS and mean BMAD SDS were significantly lower than zero. During GH treatment both increased impressively (P < 0.001). The gain in height of children with severe short stature at start (< or = -3.00 SDS), did not differ between those receiving either a GH dose of 33 or 66 microg/kg/day. CONCLUSION: Three years of GH treatment in short children born SGA results in a normalization of height during childhood. Also, bone maturation increased proportionately to the height gain. At start, mean values of BMD and BMAD were significantly reduced but normalized during GH treatment. We did not find an indication to treat very short SGA children (H SDS < or = -3.00) with a higher GH dose. We rather suggest to start GH treatment at an early age in order to achieve a normal height before puberty starts.