Estimation of the leucine and histidine requirements for piglets fed a low-protein diet.

Reduction of the CP content in the diets of piglets requires supplementation with crystalline essential amino acids (AA). Data on the leucine (Leu) and histidine (His) requirements of young pigs fed low-CP diets are limited and have primarily been obtained from nonlinear models. However, these models do not consider the possible decline in appetite and growth that can occur when pigs are fed excessive amounts of AA such as Leu. Therefore, two dose-response studies were conducted to estimate the standardised ileal digestible (SID) Leu : lysine (Lys) and His : Lys required to optimise the growth performance of young pigs. In both studies, the average daily gain (ADG), average daily feed intake (ADFI) and gain-to-feed ratio (G : F) were determined during a 6-week period. To ensure that the diets had sub-limiting Lys levels, a preliminary Lys dose-response study was conducted. In the Leu study, 60 35-day-old piglets of both sexes were randomly assigned to one of five treatments and fed a low-CP diet (15%) with SID Leu : Lys levels of 83%, 94%, 104%, 115% or 125%. The His study used 120 31-day-old piglets of both sexes, which were allotted to one of five treatments and fed a low-CP diet (14%) with SID His : Lys levels of 22%, 26%, 30%, 34% or 38%. Linear broken-line, curvilinear-plateau and quadratic-function models were used for estimations of SID Leu : Lys and SID His : Lys. The minimum SID Leu : Lys level needed to maximise ADG, ADFI and G : F was, on average, 101% based on the linear broken-line and curvilinear-plateau models. Using the quadratic-function model, the minimum SID Leu : Lys level needed to maximise ADG, ADFI and G : F was 108%. Data obtained from the quadratic-function analysis further showed that a ±10% deviation from the identified Leu requirement was accompanied by a small decline in the ADG (-3%). The minimum SID His : Lys level needed to maximise ADG, ADFI and G : F was 27% and 28% using the linear broken-line and curvilinear-plateau models, respectively, and 33% using the quadratic-function model. The preferred model to estimate the His requirement was the curvilinear-plateau model. However, a 10% reduction in the SID His : Lys level was associated with an 11% reduction in the ADG. In conclusion, the SID Leu : Lys level needed to maximise growth was 108% when using the quadratic-function model as the best-fitting model. The minimum SID His : Lys level required to optimise growth was 28% when using the curvilinear-plateau model as the best-fitting model.

Bioavailability of zinc from different sources in pigs.

In contrast to inorganic Zn, organic Zn sources are absorbed via peptide or AA transport systems resulting in a higher digestibility and availability. Bioavailability of organically bound Zn seems also to be influenced by the type of complex being used. Forty-two gilts (Large white × Landrace) with initial BW of 24 ± 1.4 kg were allotted to 6 treatments of 7 pigs each. Pigs were fed diets based on corn (Zea mays), barley (Hordeum vulgare), and soybean (Glycine max) meal containing either low or high Zn supplementation with ZnO, Zn-Met 1:2 complex, Zn-Gly, Zn proteinate (Zn-Prot), or Zn-yeast. Diets were fed during a 10-d adaptation followed by a 4-d quantitative collection. Daily feed allowance was restricted to 1400 g/pig. Pigs were weighed at the start and end of adaptation and collection and feed consumption was monitored daily. Dietary Zn addition was 10 and 100 mg/kg feed for ZnO and 10 mg/kg feed for other Zn sources. Corresponding ADG ranged from 437 to 587 g with the lowest (P < 0.05) ADG for 10 ppm ZnO. Only Zn-Met addition increased (P < 0.02) Zn digestibility and retention (P < 0.05). Organically bound Zn, in particular Zn from Zn-Met 1:2 and Zn-yeast, can replace higher dosages of ZnO due to better bioavailability indicating that type of chelate is important for Zn retention. Organically bound Zn may reduce Zn excretion, which consequently may lower the environmental impact.

Estimation of the optimum ratio of standardized ileal digestible isoleucine to lysine for eight- to twenty-five-kilogram pigs in diets containing spray-dried blood cells or corn gluten feed as a protein source.

Two growth assays and 1 N balance trial were conducted to determine the standardized ileal digestible (SID) Ile:Lys ratio in 8- to 25-kg pigs using spray-dried blood cells or corn gluten feed as a protein source. In Exp. 1, 48 individually penned pigs (initial BW = 7.7 kg) were used in a 6-point SID Ile titration study (analyzed SID Ile of 0.36, 0.43, 0.50, 0.57, 0.64, and 0.72%) by addition of graded levels of L-Ile. The basal diet contained 1.00% SID Lys, 18.4% CP, and 13.6 MJ of ME/kg. Diets were based on wheat, barley, corn, and 7.5% spray-dried blood cells as a protein source. Dietary SID Leu and Val levels were 1.61 and 1.02%, respectively. For the 35-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.04) with increasing SID Ile:Lys. Estimates of optimal SID Ile:Lys ratios were 59% for ADG and ADFI. In Exp. 2, 24 N balances were conducted using the Exp. 1 diets (12 pigs; individually penned; average BW = 11.5 kg). Pigs were fed 3 times daily with an amount equal to 1.0 MJ of ME/kg of BW(0.75). Preparation and collection periods (7 d each) were repeated after rearranging the animals to treatments. Increasing the dietary SID Ile:Lys ratio increased N retention linearly (P < 0.01), and N utilization linearly (P < 0.01) and quadratically (P < 0.01). An optimal SID Ile:Lys ratio of 54% was estimated for N retention. In Exp. 3, 48 individually penned pigs (initial BW = 8.0 kg) were fed grain-based diets in a 6-point SID Ile titration (analyzed SID Ile of 0.35, 0.41, 0.49, 0.56, 0.62, and 0.69%). Dietary SID Ile was increased by graded addition of L-Ile. The basal diet contained 0.97% SID Lys, 16.8% CP, and 13.6 MJ of ME/kg. In contrast to Exp. 1 and 2, spray-dried blood cells were excluded and corn gluten feed was used as a protein source. Dietary SID Leu and Val were set to 1.05 and 0.66%. For the 42-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.01) with increasing SID Ile:Lys. Estimated optimal SID Ile:Lys ratios were 54, 54, and 49 for ADG, ADFI, and G:F, respectively. These experiments suggest that the optimal SID Ile:Lys ratio depends on diet composition. In Exp. 1, AA imbalances because of increased Leu contents may have led to increased Ile nutritional needs. For ADG and ADFI, an optimum SID Ile:Lys ratio of 54% was estimated for 8- to 25-kg pigs in diets without Leu excess.

Holoprosencephaly and cleidocranial dysplasia in a patient due to two position-effect mutations: case report and review of the literature.

Holoprosencephaly (HPE) is a genetically heterogeneous developmental field defect in which midline cleavage of the forebrain and craniofacial structures is impaired. Based on the analysis of HPE patients with chromosome rearrangements, at least six loci for the disorder have been assigned. The sonic hedgehog gene (SHH) at 7q36 has been identified as the HPE3 locus. Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal disorder characterized by clavicular, pelvic and dental anomalies. It is caused by mutations in the osteoblast-specific transcription factor CBFA1/RUNX2, which maps to 6p21. We report a 20-year-old female with premaxillary agenesis (part of the HPE spectrum), as well as skeletal abnormalities and impacted teeth reminiscent of CCD. She carries a de novo 6;7 reciprocal translocation, with breakpoints at 6p21.1 and 7q36. We have shown previously that the 7q36 breakpoint maps 15 kb telomeric to the 5' end of SHH, which explains the patient's HPE phenotype. Now, using fluorescence in situ hybridization, we have identified a P1 artificial chromosome clone 800 kb upstream of CBFA1/RUNX2 that spans the 6p breakpoint. We propose that the proband's complex phenotype is due to two position-effect (PE) mutations, one at each translocation breakpoint, which have altered the expression of the SHH and CBFA1/RUNX2 genes. The role of PE mutations in human disease is also reviewed.

Requirement of true ileal digestible threonine of growing and finishing pigs.

Ninety-six crossbred barrows and gilts were used to investigate the optimum supply of true ileal digestible threonine for growing (approximately 35-65 kg body weight) and finishing (approximately 65-110 kg body weight) pigs. For this purpose, according to a bifactorial arrangement in the grower as well as in the finisher phase four dietary threonine levels were combined with two dietary levels of lysine. Measurement criteria were body weight gain, feed intake, feed conversion rate and carcass characteristics. In the grower stage at the lower lysine level daily gain increased numerically (p < 0.1) and the feed to gain ratio decreased significantly with an increasing dietary true ileal digestible threonine concentration. Increasing the true ileal digestible lysine concentration of the diet from 7.8 to 9.2 g/kg increased average daily gain in the grower stage significantly from 815 to 855 g and decreased the feed to gain ratio significantly. In finishing pigs, daily gain and feed to gain ratio were significantly improved by an increasing dietary true ileal digestible threonine concentration from 821 to 902 g and from 3.14 to 2.94 kg/kg, respectively, but not by the differing lysine supply. As in the grower stage, barrows consumed more feed than gilts at similar growth rates and this resulted in a significantly reduced feed to gain ratio in gilts compared with barrows. The requirements of true ileal digestible threonine for optimize both, daily gain and feed to gain ratio, as derived by the broken-line model were 10.3 g/animal and day for growing and 10.7 g/animal and day for finishing pigs respectively.

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24 kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine + cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276 mg per 12 h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150 mg per 12 h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.

Velo-cardio-facial syndrome: Implications of microdeletion 22q11 for schizophrenia and mood disorders.

Velo-cardio-facial syndrome (VCFS) is a congenital malformation syndrome with variable phenotypic features that has been associated with chromosomal microdeletion 22q11.2. Psychiatric disorders have been reported to be highly prevalent in individuals with this syndrome, and the objective of this study was to assess the nature and extent of psychopathology among individuals with VCFS. We studied 20 children and adolescents with 22q11 deletions determined by fluorescence in situ hybridization (FISH). Control subjects were 11 nondeleted siblings who were the closest age match to the affected subjects. Both affected and control subjects were assessed using two standardized psychiatric research instruments. The results of this study confirmed the high rate of psychiatric disorders among VCFS subjects (60% of our subjects). Of the specific types of disorders, only mood disorders were significantly more common among VCFS subjects compared to sibling controls, with eight VCFS subjects having mood disorders compared with none of the control subjects (P<0.02). Three affected subjects had schizotypal traits comorbid with a mood disorder. In addition, disruptive behavior disorders were frequently diagnosed among VCFS subjects. Using a dimensional measure of psychopathology, significant differences between VCFS subjects and sibling controls were found on three scales: ADHD (P<0.02), separation anxiety (P<0.02), and depression (P<0.01). VCFS subjects were achieving significantly less well academically and requiring significantly more special educational assistance than sibling controls. Follow-up data were available on two subjects, both of whom had been diagnosed with schizophrenia. Further research on psychopathology in VCFS may provide a model of how a specific genetic defect can lead to the development of psychiatric disorders.

Cutaneous telangiectasias, sparse hair, and type I membranoproliferative glomerulonephritis.

We report the unusual association of normocomplementemic type I membranoproliferative glomerulonephritis in a 10-year-old girl with sparse red hair, absent eyebrows and eyelashes, cutaneous telangiectasias, and an atrial septal defect.

Research note: investigation on the metabolism of glycerol in the rumen of bulls.

Two bulls, each fitted with rumen and duodenal cannulas, received (in addition to a hay-grain diet) twice daily an infusion of 200 g glycerol into the rumen over a period of six days. During this preliminary in vivo investigation, the influence of a glycerol application on the rumen environment over a six-day adaptation period was examined. Samples of rumen fluid were collected daily, two hours after glycerol infusion. An additional 15N-urea application into the rumen was given on days 1 (without glycerol infusion), 3 and 7 (with glycerol infusion). Extra samples of rumen fluid and blood plasma (from puncture of vena jungularis) were taken through the 12th hour following urea application. Rumen fluid pH was reduced due to glycerol intake from 6.3 (day 1, without glycerol) to 5.4 by day 7. Molar proportion of acetic acid to propionic acid decreased from 3.5 (day 1) to 2.1 (days 6 and 7). Average glycerol disappearance rate from the rumen was 4.7 gl-1 h-1 for the first hour. Only small amounts of glycerol could be detected in the duodenal digesta. Blood plasma glycerol content was significantly higher after glycerol application (0.061 mmol l-1 vs. 0.019 mmol l-1). The incorporation of 15N into the rumen bacteria and the proportion of bacterial N (as percent of TCA-precipitable N in the rumen fluid) were lower after glycerol influsion. These results, coupled with the lower concentration of iso-acids (isobutyric and isovaleric acids) in the rumen fluid, indicate that the high amount of glycerol infusion (10% of DMI) reduced protein metabolism of rumen bacteria throughout the experimental period.

Congenital cytoplasmic body myopathy with survival motor neuron gene deletion or Werdnig-Hoffmann disease.

A 5-week-old boy became rigid and developed cardiac arrest after receiving succinylcholine. He was resuscitated and ventilated but died at 5 months. Muscle biopsy demonstrated no neurogenic features and numerous cytoplasmic bodies, suggesting the possibility of congenital myopathy with cytoplasmic bodies. However, molecular analysis revealed a homozygous deletion of exons 7 and 8 of the survival motor neuron (SMN) gene, suggesting that the patient had Werdnig-Hoffmann disease. We recommend that every patient with congenital cytoplasmic body myopathy be tested for SMN gene deletion.

FGFR2 mutation associated with clinical manifestations consistent with Antley-Bixler syndrome.

The Antley-Bixler syndrome (ABS) is a rare syndrome with synostosis of cranial sutures and elbow joints as minimal diagnostic criteria. The inheritance has been suggested to be autosomal recessive based on two families with sib recurrence with both sexes being affected, and two cases born to consanguineous parents. We report the first case of ABS associated with an apparent dominant de novo mutation in the fibroblast growth factor receptor 2 (FGFR2) gene. The patient was found to be heterozygous for a C-->G transversion at nucleotide 1064, which predicts a Ser351Cys amino acid substitution in the IgIII domain of FGFR2. Apart from the craniosynostosis and elbow ankylosis, our patient also presented with severe spinal dysraphism, the first report of such a finding in association with ABS. This suggests that FGFR2 is expressed as early as the fourth week of embryogenesis when somite formation occurs. We propose that the Antley-Bixler syndrome is an autosomal dominant condition with possible gonadal mosaicism. Alternatively, there may be two types of ABS: an autosomal dominant form and an autosomal recessive form. In light of our findings, FGFR mutations should be looked for in other craniosynostosis patients with elbow synostosis.

Familial ileal perforation: prenatal diagnosis and postnatal follow-up.

We report sibs (a brother and a sister) who presented prenatally with ultrasound findings of meconium peritonitis and postnatally were found to have perforation of the terminal ileum. The sister presented with fetal ultrasound findings of severe ascites and peritoneal calcifications. She had no prenatal intervention and was born at 38 weeks' gestation. Laparatomy revealed perforation of the terminal ileum with meconium peritonitis. Her post-surgical course was uncomplicated and at 30 months of age her growth and development are normal. Her brother presented prenatally with signs of meconium peritonitis including severe ascites and peritoneal calcifications. Prenatal aspiration of the ascitic fluid was performed and unlike his sister he was born prematurely, was operated on at 8 days, and developed bronchopulmonary dysplasia. He is currently 1 year old and has normal growth and development. The aetiology of the ileal perforation is not known. There were no findings suggesting connective tissue disorder and the aetiology of the intestinal perforation is not known. The occurrence of the same rare abnormality in sibs of different sexes points towards an autosomal recessive disorder.

MRI findings in macrocephaly-cutis marmorata telangiectatica congenita.

We describe a child with macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC), cherry red macules, megalencephaly with hemifacial and segmental overgrowth, macrosomia, and cutis marmorata telangiectasia congenita of the trunk, and visceral and subcutaneous cavernous hemangiomas. The megalencephaly is accompanied by MRI findings of CNS dysgenesis with protrusion of the cerebellar tonsils through the foramen magnum (Chiari I), lumbar syrinx, and hydrops of the optic nerves. The report of this additional patient further confirms the newly described macrocephaly-cutis marmorata telangiectatica congenita as a distinct clinical phenotype.

Cytogenetic rearrangements involving the loss of the Sonic Hedgehog gene at 7q36 cause holoprosencephaly.

Holoprosencephaly (HPE) is a genetically heterogeneous disorder that affects the midline development of the forebrain and midface in humans. As a step toward identifying one of the HPE genes, we have set out to refine the HPE3 critical region on human chromosome 7q36 by analyzing 34 cell lines from families with cytogenetic abnormalities involving 7q, 24 of which are associated with HPE. Genomic clones surrounding the DNA marker D7S104, which has previously been shown to be in the HPE3 critical region, have been examined by fluorescent in situ hybridization and microsatellite analysis of our panel of patient cell lines. We report the analysis of a cluster of four translocation breakpoints within a 300-kb region of 7q36 that serves to define the minimal critical region for HPE3 and that has directed the search for candidate genes. The human Sonic Hedgehog (hSHH) gene maps to this region and has been shown to be HPE3 on the basis of mutations within the coding region of the gene. We present evidence that cytogenetic deletions and/or rearrangements of this region of chromosome 7q containing Sonic Hedgehog, and translocations that may suppress Sonic Hedgehog gene expression through a position effect are common mechanisms leading to HPE.

Computerized videokeratography of keratoconus kindreds.

OBJECTIVE: To assess the role of heredity in the development of keratoconus. DESIGN: Prospective study. SETTING: Eye clinic providing secondary and tertiary ophthalmic care in Toronto. PATIENTS: Thirty-nine patients with keratoconus (57 eyes) and 48 relatives of 11 patients with keratoconus. The corneal topography of the family members was compared with that of a group of 68 volunteer control subjects (136 eyes) without clinical evidence or a family history of keratoconus. OUTCOME MEASURES: Three quantitative measures derived from computerized videokeratography: the relative steepness of the inferior cornea versus the superior cornea, central corneal power and the difference in central corneal power between the two eyes. All the data were statistically analysed with the use of nonparametric discriminant analysis. RESULTS: Fifteen family members who were believed to be clinically normal on the basis of refraction, keratometry and slit-lamp examination has statistically significant topographic abnormalities suggestive of early or mild keratoconus. CONCLUSIONS: The presence of these findings in family members of patients with keratoconus may represent the incomplete expression of a gene contributing to the development of the condition. Pedigree analysis suggested an autosomal dominant inheritance pattern in 9 of the 11 families. Our results underline the value of videokeratography for accurate family pedigree analysis and the diagnosis of keratoconus.

Deletion 4q21/4q22 syndrome: two patients with de novo 4q21.3q23 and 4q13.2q23 deletions.

We report on 2 patients with de novo proximal interstitial deletions of the long arm of chromosomes 4: in one the deletion resulted in monosomy (4)(q21.3q23), in the other it produced monosomy (4)(q13.2q23). Review of 9 cases of deletions involving the 4q21/4q22 region reported previously detected a characteristic phenotype in 8 patients. This phenotype was present in our patients. We conclude that the deletion in the 4q21/4q22 region results in a specific clinical syndrome associated with central nervous system overgrowth that may be a result of anomalous imprinting in the 4q21/4q22 region.

Hirschsprung disease, postaxial polydactyly, and atrial septal defect.

We report on an infant girl with Hirschsprung disease, postaxial polydactyly, and atrial septal defect who was born to a consanguineous Iraqi couple. A similar condition of aganglionic megacolon, postaxial polydactyly, and ventricular septal defect with a presumed autosomal recessive (AR) inheritance was reported by Laurence in two sibs [Laurence et al.; J Med Genet 12: 334-338, 1975].

Cloning and characterization of a novel bicoid-related homeobox transcription factor gene, RIEG, involved in Rieger syndrome.

Rieger syndrome (RIEG) is an autosomal-dominant human disorder that includes anomalies of the anterior chamber of the eye, dental hypoplasia and a protuberant umbilicus. We report the human cDNA and genomic characterization of a new homeobox gene, RIEG, causing this disorder. Six mutations in RIEG were found in individuals with the disorder. The cDNA sequence of Rieg, the murine homologue of RIEG, has also been isolated and shows strong homology with the human sequence. In mouse embryos Rieg mRNA localized in the periocular mesenchyme, maxillary and mandibular epithelia, and umbilicus, all consistent with RIEG abnormalities. The gene is also expressed in Rathke's pouch, vitelline vessels and the limb mesenchyme. RIEG characterization provides opportunities for understanding ocular, dental and umbilical development and the pleiotropic interactions of pituitary and limb morphogenesis.