The nuclear localization domain of the MEF2 family of transcription factors shows member-specific features and mediates the nuclear import of histone deacetylase 4

Targeting of myocyte enhancer binding factor 2 (MEF2) proteins to the nucleus depends on a C-terminal bipartite nuclear localization signal (NLS). By expression of green fluorescent protein (GFP)/MEF2 fusion proteins in transfected myoblasts, we show that MEF2C contains an additional 13 amino acids domain, located immediately upstream of the NLS, which contributes to its nuclear retention. We also show that the NLS present in MEF2 proteins is required for efficient nuclear localization of histone deacetylase 4 (HDAC4). In muscle cells, transfected HDAC4 is largely cytoplasmic or, to a lesser extent, pancellular. Co-transfection of either MEF2A or MEF2C causes HDAC4 to accumulate in the nucleus in association with MEF2. This effect strongly depends on MEF2 NLS; it also requires the specific interaction of HDAC4 with MEF2, since the isolated NLS is not sufficient for targeting HDAC4 to the nucleus and other nuclear proteins, such as NF-Y, cannot substitute MEF2. Therefore, we demonstrate that HDAC4, different from HDAC5, is mainly a cytoplasmic resident protein, requiring a trans-acting NLS for nuclear localization. The physiological implications of MEF2 carrying its own inhibitor to the nucleus are discussed.

The costs of childhood epilepsy in Italy: comparative findings from three health care settings

PURPOSE

To determine the direct costs of epilepsy in a child neurology referral population, stratified by disease, duration, and severity, comparing three different health care settings [i.e., teaching or clinical research (CR) hospitals, general hospitals, and outpatient services].

METHODS

Patients were accepted if they had confirmed epilepsy and were resident in the center catchment area. Eligible subjects were grouped in the following categories: (a) newly diagnosed patients; (b) patients with epilepsy in remission; (c) patients with active non-drug-resistant epilepsy; and (d) those with drug-resistant epilepsy. Over a 12-month period, data regarding the consuming of all resources (i.e., consultations, tests, hospital admissions, drugs), were collected for each patient. Using the Italian National Health Service tariffs, the unit cost of each resource was calculated and indicated in Euros, the European currency.

RESULTS

A total of 189 patients was enrolled by two teaching-CR hospitals, two general hospitals, and two outpatient services. The patients were evenly distributed across the four categories of epilepsy. The mean annual cost per person with epilepsy was 1,767 Euros. Drug-resistant epilepsy was the most expensive category (3,268 Euros) followed by newly diagnosed epilepsy (1,907 Euros), active non-drug-resistant epilepsy (1,112 Euros), and epilepsy in remission (844 Euros). Costs were generally highest in teaching-CR hospitals and lowest in outpatient services. Hospital services were the major cost in all epilepsy groups, followed by drugs.

CONCLUSIONS

The cost of epilepsy in children and adolescents in Italy tends to vary significantly depending on the severity and duration of the disease Hospitals services and drugs are the major sources of costs. The setting of health care plays a significant role in the variation of the costs, even for patients in the same category of epilepsy.

Detection and preliminary characterization of a bacteriocin (plantaricin 35d) produced by a Lactobacillus plantarum strain

Lactic acid bacteria (134) from Italian sausages were tested for the production of antimicrobial substances (bacteriocins). Six percent of these showed antibacterial activity against one or several closely related microorganisms used as indicators. Lactobacillus plantarum 35d in particular produced a bacteriocin of high activity (320 AU ml(-1)) and a wide range of antimicrobial activity including S. aureus, L. monocytogenes, and A. hydrophila. The bacteriocin withstood heating at 80 degrees C for 120 min and storage at 4 degrees C for 6 months. The mode of action was identified as bactericidal. The apparent molecular weight of the bacteriocin extracted with n-butanol was estimated to be 4.5 kDa.

Proton magnetic resonance spectroscopy (1H-MRS) of the cerebrum in two young infants with Zellweger syndrome

Cerebral metabolic abnormalities have been previously detected by 1H-MRS in infants with the Zellweger syndrome as young as 3 months. We hypothesized that metabolic abnormalities could also be found shortly after birth. Two fullterm infants with Zellweger syndrome were studied at 12 days and two months of age, respectively, using single voxel 1H-MRS. In the first case 1H-MRS was performed using PRESS with variable TE (31, 136, 272 ms); in the second, STEAM and PRESS sequences were used with different TE (STEAM at 30 and 144 ms; PRESS at 270 ms). In both cases a significant decrease of N-acetylaspartate (NAA) and an abnormal signal at 1.33 and 0.9 ppm, consisting of lactate (Lac) and lipids (Lip) were found. The reported MRS abnormalities, although not specific for peroxisomal dysfunctions, may support the suspicion of Zellweger syndrome and may indicate direct referral to the specific laboratory and molecular studies necessary to establish the diagnosis and prognosis of this syndrome.

Glutamatergic synaptic responses and long-term potentiation are impaired in the CA1 hippocampal area of calbindin D(28k)-deficient mice

The contribution of the cytosolic calcium binding protein calbindin D(28K) (CaBP) to glutamatergic neurotransmission and synaptic plasticity was investigated in hippocampal CA1 area of wild-type and antisense transgenic CaBP-deficient mice, with the use of extracellular recordings in the ex vivo slice preparation. The amplitude of non-N-methyl-D-aspartate receptor (non-NMDAr)-mediated extracellular field excitatory postsynaptic potentials (fEPSPs) recorded in control medium was significantly greater in CaBP-deficient mice, whereas the afferent fiber volley was not affected. In contrast, the amplitude of NMDAr-mediated fEPSPs isolated in a magnesium-free medium after blockade of non-NMDAr and GABAergic receptors was significantly depressed in these animals. No alteration in the magnitude of paired-pulse facilitation was found, indicating that the presynaptic calcium mechanisms controlling glutamate release were not altered in CaBP-deficient mice. The magnitude and time course of the short-term potentiation (STP) of fEPSPs induced by a 30 Hz conditioning stimulation, which was blocked by the NMDAr antagonist 2-amino-5-phosphonovalerate acid (2-APV), was not impaired in the transgenic mice, whereas long-term potentiation (LTP) induced by a 100 Hz tetanus was not maintained. The long-term depression (LTD) induced by low-frequency stimulation (1 Hz, 15 min) in the presence of the GABA antagonist bicuculline was not altered. These results argue for a contribution of CaBP to the mechanisms responsible for the maintenance of long-term synaptic potentiation, at least in part by modulating the activation of NMDA receptors.

Cellular calcium handling in brain slices from calbindin D28k-deficient mice

Cellular calcium handling was examined in brain slices from transgenic antisense mice with a regional deficiency in the neuronal calcium binding protein calbindin D28k and from their non transgenic wild type litter mate controls. Depolarization of brain slices with NMDA or potassium produced a prolonged elevation of neuronal calcium signal in neurons in brain slices from calbindin D28k-deficient transgenic mice. This effect was selective and was seen only in brain areas where the antisense construct produced a significant depletion of calbindin D28k protein. In other regions where calbindin D28k protein was not modified by the construct and in all glial cells whether from wild type or transgenic mice, cellular calcium handling was normal.

Central precocious puberty in 48,XXYY Klinefelter syndrome variant

We report the first case of central precocious puberty in a patient with 48,XXYY Klinefelter syndrome variant. We also report clinical characteristics, growth pattern, endocrine data and pathological testicular findings. The patient did not receive medical care for his precocious pubertal development, because of adequate height prognosis, and reached normal height for both his target height and Klinefelter patients. Since precocious puberty seems to occur in Klinefelter syndrome and its variants, we advise karyotype analysis in boys with mental retardation, gynecomastia, small testes and precocious onset of puberty.

Construction and in vitro functional evaluation of a low-density lipoprotein receptor/transferrin fusion protein as a therapeutic tool for familial hypercholesterolemia

A cDNA sequence encoding a soluble form of the human low-density lipoprotein receptor (LDL-R) was produced by RT-PCR amplification. This form of the receptor contains the N-terminal cysteine-rich domain, the EGF homology domain, and the serine/threonine-rich domain, but lacks the membrane anchor as well as the cytoplasmic domain. By the same technical approach a cDNA sequence encoding rabbit transferrin was generated. In-frame fusion of the two cDNAs produced a sequence encoding a chimeric protein potentially capable of binding LDL on the N-terminal side and the transferrin receptor on the C-terminal side. It was expected that LDL bound to the chimeric protein could be internalized, targeted to an acidic compartment, and processed through the pathway of the transferrin receptor. Cells transfected with the LDL-R/transferrin cDNA translate, glycosylate, and secrete the corresponding protein in the culture medium. The secreted protein binds LDL in a ligand-blotting experiment. Finally, the chimeric protein mediates the binding and internalization of LDL in mutant cells lacking the LDL receptor. In fact, Watanabe rabbit fibroblasts, incubated with the chimeric protein show a fourfold increase in LDL binding, a fivefold increase in LDL internalization, and a sixfold increase in LDL degradation, with respect to unincubated fibroblasts.

Presence of a functional vitamin D receptor does not correlate with vitamin D3 phenotypic effects in myeloid differentiation

Although VDR is expressed in all the acute myeloid leukemia cell populations studied, most of these leukemias do not exhibit any phenotypic response when exposed to VD. To determine whether VD resistance is related to an altered VDR function, we performed an analysis of VDR expression, phosphorylation, DNA binding capacity and transactivation activity in several leukemic myeloid cell lines arrested at different levels of maturation. Our results indicate that VD induces a clear phenotypic effect, i.e. terminal monocytic differentiation, only in leukemic cells of M2/M3 (intermediate myeloblasts) and M5 (monoblasts) types but not in erythroid precursor cells, early leukemic myeloblasts (M0/M1 type) and promyelocytes (M3 type). VDR expression and function are evident in all the nuclear extracts obtained from the different myeloid cell lines after 12 h of VD treatment, but VD activation of monocytic differentiation is limited to a narrow differentiation window characterized by the M2 type myeloid cellular context.

Androgen-receptor blockade does not impair bone mineral density in adolescent females

The effect of peripheral androgen hypersensitivity on bone mineral density (BMD) was investigated in a group of adolescent women with idiopathic hirsutism (n = 17; mean age 17.0 +/- 1.7 years). The effect of long-term androgen-receptor blockade with flutamide (500 mg daily in two divided doses for 12 months) on BMD was assessed too. BMD was measured at lumbar spine (L2-L4) by a dual energy X-ray densitometer. Before flutamide treatment, patient BMD (1.14 +/- 0.07 g/cm2) was not significantly different from that of the control group (1.16 +/- 0.12 g/cm2, n = 22), and was normal for age and sex (BMD 0.14 +/- 0.69 SDS, P = NS vs. 0). After 12 months of treatment, absolute BMD in patients increased (1.18 +/- 0.08 g/cm2, P < 0.002), but SDS BMD did not change (0.21 +/- 0.72, P = NS vs. baseline). Flutamide treatment determined a clinical, marked improvement of androgen hypersensitivity (Ferriman-Gallwey score: before 22.0 +/- 6.2; 6 months: 13.2 +/- 6.4, P < 0.003; 12 months; 7.6 +/- 4.1, P < 0. 001; acne score: before 3.8 +/- 0.8; 3 months 0.8 +/- 0.5, P < 0. 001; later disappeared). The serum levels of 3alpha-androstenediol-glucoronide decreased (before: 8.6 +/- 1.1 microg/liter; 12 months: 7.2 +/- 1.0 microg/liter, P < 0.02), whereas the other endocrinological parameters did not change. No relationship was found between BMD and clinical or biochemical parameters of hyperandrogenism. We concluded that in adolescent women, peripheral hyperandrogenism is not associated with abnormal BMD; long-term treatment with flutamide, which blocks the androgen receptor, does not alter their BMD.

Absence of MEF2 binding to the A/T-rich element in the muscle creatine kinase (MCK) enhancer correlates with lack of early expression of the MCK gene in embryonic mammalian muscle

During skeletal muscle development, different types of muscle fibers are generated, which express different combinations of muscle-specific gene products. For example, the muscle creatine kinase gene (MCK) is highly expressed in fetal but not embryonic myotubes. We performed transient transfections of CAT reporter constructs, driven by the MCK promoter with variable lengths of 5'-flanking sequence, into primary cultures of embryonic and fetal muscle cells. Reporter activity was observed in fetal but not embryonic muscle cells. We assayed the ability of nuclear extracts prepared from embryonic and fetal muscle and C2C12 myotubes to bind specific regulatory elements in the MCK enhancer. The profile of DNA/protein complexes resulting from electrophoretic mobility shift assays was qualitatively the same with all extracts used when the oligonucleotide probes represented the MCK-E-box, MHox site, CArG-box, and AP2 site. In contrast, no binding activity to the MEF2 site was observed with embryonic nuclear extract. Interestingly, MEF2 mRNAs and proteins were detected in both fetal and embryonic muscle, with the exception of the MEF2D1b isoform, which is restricted to fetal muscle. Furthermore, we found that protein phosphatase inhibitors included in the preparation of embryonic nuclear extracts or added to the medium of transfected embryonic myotubes can restore MEF2 DNA binding activity, as well as reporter activity driven by the MCK promoter and partial transcriptional activation of the endogenous MCK gene. We propose that phosphorylation of MEF2 regulates its activity and represents an important aspect of the mechanism controlling stage-specific transcription during skeletal myogenesis.

Central precocious puberty in Klinefelter syndrome: a case report with longitudinal follow-up of growth pattern

We report idiopathic central precocious puberty in a boy with Klinefelter syndrome and describe the pattern of linear growth and body proportion from the onset of precocious puberty to final height. The patient was not treated for precocious puberty. He reached adequate adult height, for both general population and normative values of Klinefelter syndrome and normal body proportions. We conclude that precocious puberty in Klinefelter syndrome may result in normal body proportion by inducing a major growth spurt of the trunk rather than in the limbs, and that adult height prognosis is not altered by precocious puberty. Given the possible occurrence of precocious puberty in Klinefelter syndrome, we advise a karyotype analysis in boys with sexual precocity, mainly in those who show small rather than enlarged testes.

Deficits in memory and hippocampal long-term potentiation in mice with reduced calbindin D28K expression

The influx of calcium into the postsynaptic neuron is likely to be an important event in memory formation. Among the mechanisms that nerve cells may use to alter the time course or size of a spike of intracellular calcium are cytosolic calcium binding or "buffering" proteins. To consider the role in memory formation of one of these proteins, calbindin D28K, which is abundant in many neurons, including the CA1 pyramidal cells of the hippocampus, transgenic mice deficient in calbindin D28K have been created. These mice show selective impairments in spatial learning paradigms and fail to maintain long-term potentiation. These results suggest a role for calbindin D28K protein in temporally extending a neuronal calcium signal, allowing the activation of calcium-dependent intracellular signaling pathways underlying memory function.

Short-term effect of testosterone treatment on reduced bone density in boys with constitutional delay of puberty

We studied bone mineral content (BMC), bone mineral density (BMD), cortical thickness/total width (CT/TW) ratio and cortical area/total area (CA/TA) ratio in boys with constitutional delay of puberty and the effect of short-term testosterone treatment on bone mass. Seventeen boys (age 13.1-15.8 years) who met the family history and the clinical criteria of constitutional delay of puberty were selected and enrolled in the study. All subjects were eating a diet assuring an adequate intake of calories and calcium. A subset of 8 boys (group A) was treated with testosterone depot (100 mg/month x 6 months) while 9 boys (group B) were not. At inclusion, BMC and BMD were reduced in the patients according to their chronological age (BMC -4.04 +/- 1.34 standard deviation scores [SDS]; BMD -2.95 +/- 0.56 SDS), statural age (BMC -1.75 +/- 0.79 SDS; BMD -1.69 +/- 0.78 SDS), and bone age (BMC -1.80 +/- 0.65 SDS; BMD -1.86 +/- 0.68 SDS). No significant differences between the groups were found (group A: BMC 0.480 +/- 0.57 g/cm, BMD 0.488 +/- 0.037 g/cm2, CT/TW ratio 0.43 +/- 0.4, CA/TA ratio 0.68 +/- 0.04; group B: BMC 0.476 +/- 0.060, p = NS vs. group A; BMD 0.491 +/- 0.036 g/cm2, p = NS vs. group A). At 12 months of follow-up, BMC, BMD, CT/TW ratio, and CA/TA ratio significantly increased in group A (BMC 0.70 +/- 0.13 g/cm, delta +41.1 +/- 28.8%, p < 0.003 vs. 0 month; BMD 0.617 +/- 0.082 g/cm2, delta +26.2 +/- 13.6%, p < 0.005 vs. 0 month; CT/TW ratio 0.52 +/- 0.05, delta +20.59 +/- 10.65%, p < 0.001 vs. 0 month; CA/TA ratio 0.77 +/- 0.05 vs. 0 month; CT/TW ratio 13.60 +/- 6.65%, p < 0.004 vs 0 month), but not in group B (BMC: 0.48 +/- 0.05 g/cm; delta +5.1 7.8%, p = NS vs. 00 month; BMD: 0.492 +/- 0.037 g/cm2; delta +0.54 +/- 8.7%, p = NS vs. 0 month; CT/TW ratio 0.44 +/- 0.04, delta +4.04 +/- 6.75%, p = NS vs. 0 month; CA/TA ratio 0.68 +/- 0.05, delta +2.39 +/- 5.90%, p = NS vs. 0 month). We conclude that boys with constitutional delay of puberty have reduced BMC and BMD. The delay in statural and bone ages did not totally account for the decreased bone mass. Testosterone treatment for 6 months significantly increased BMC, BMD, CT/TW ratio, and CA/TA ratio in these patients, but definitive conclusions on the efficacy of the treatment in improving adult bone mass can be drawn only when our patients reach early childhood.

Effect of combined treatment with gonadotropin releasing hormone analogue and growth hormone in patients with central precocious puberty who had subnormal growth velocity and impaired height prognosis

Growth hormone-insulin-like growth factor-I status and response to growth hormone therapy (0.6 IU/kg/week sc, six times a week for 12 months) were evaluated in 12 girls (chronological age 9.4 +/- 1.6 years) suffering from central precocious puberty with growth velocity less than 4 cm/year and no substantial increase or decrease in predicted adult height during gonadotropin releasing hormone Bn-RH) analogue treatment (D-Trp6-LH-RH, 60 micrograms/kg im/28 days). At baseline, large variations were observed in nocturnal growth hormone (GH) means (pathological values stimulated levodopa GH peaks (pathological values (< 10.0 micrograms/l) 28.6%) and serum insulin-like growth factor-I (IGF-I) levels. Neither GH-nor IGF-I levels were correlated with growth velocity. During recombinant GH therapy, growth velocity increased significantly (baseline 3.0 +/- 0.9 cm/year; 6 months 6.4 +/- 1.9 cm/year, p < 0.001 versus baseline; 12 months 6.0 +/- 1.3 cm/year, p < 0.0001 versus baseline). There was a significant increase in height SDS for bone age (baseline -1.6 +/- 0.5 SDS; 12 months -1.04 +/- 0.6 SDS; p < 0.002) and in predicted adult height (baseline 152.0 +/- 3.6 cm; 12 months 155.9 +/- 3.4 cm; p < 0.002). Our results suggest that combined therapy with Gn-RH analogues and recombinant GH can improve growth velocity and predicted adult height in girls with central precocious puberty and impaired height prognosis during Gn-RH analogue treatment.

Parathyroid hormone-related protein in healthy pregnant women

The object of this study was to determine whether increased circulating levels of parathyroid hormone-related protein (PTH-rp) may explain the increased parathyroid hormone (PTH) bioactivity in pregnancy. In 41 healthy pregnant women (age 19-41 years), PTH-rp and corrected calcium levels were measured and compared with those of nonpregnant control women (n = 18, age 20-39 years). PTH-rp and corrected calcium levels were significantly higher in pregnant women (PTH-rp 21.9 +/- 7.9 pg/ml, P < 0.001; corrected calcium 2.38 +/- 0.07 mmol/liter, P = 0.001) than in nonpregnant women (PTH-rp 10.3 +/- 7.8 pg/ml; corrected calcium 2.30 +/- 0.10 mmol/liter). Our data indicate that circulating PTH-rp levels may significantly increase in pregnancy, suggesting a possible role of this peptide in the modification of calcium homeostasis in pregnant women.

Specific binding to vitamin D response elements of chicken intestinal DNA-binding activity is not related to the vitamin D receptor

In this report we confirm that the putative vitamin D response element (VDRE), located between -320 and -306 in the chicken calbindin-D28K gene, is not a binding site for the vitamin D3 receptor (VDR). In examining the ability of chicken intestinal nuclear extracts (CINE) to bind known VDREs, we observed a specific VDRE-binding activity, which is distinct from VDR. In fact, VDR-depleted CINE retains the ability to bind the rat osteocalcin VDRE. The VDRE-binding activity binds DNA with high affinity and contacts it at the same guanine residues as VDR. Its specificity in binding structural variants of the AGGTCA repeat is broader than that of VDR, as direct repeats spaced by 3, 4, and 5 base pairs are almost equally effective competitors when added to the probe in molar excess. Palindromic arrangements of the same motif are lower affinity competitors. The retinoid-X receptor is involved in the binding complex, as incubation of CINE with antibody to retinoid-X receptor results in a quantitative supershift. Antibodies to retinoic acid receptors (RAR alpha and -beta), T3 receptor, or chicken ovalbumin up-stream promoter-transcription factor had no apparent effect. These data suggest that species specificity is a relevant aspect of VDR/VDRE recognition, and that a novel factor(s), different from VDR, might be involved in the effect of vitamin D on gene expression.

Reduction of bone density: an effect of gonadotropin releasing hormone analogue treatment in central precocious puberty

Gonadal steroids drive the significant bone mineral increase that occurs at puberty. Oestrogen deprivation in women results in bone loss. We investigated bone mineralization by single photon absorptiometry in girls with central precocious puberty (n = 13, age 3.8-8.5 years) before and during 1 year of treatment with gonadotropin releasing hormone analogue (GnRH-a = long-acting D-Trp6-GnRH, 60 micrograms i.m. every 28 days). Before GnRH-a therapy, bone mineral density (BMD) was significantly higher in patients than in ten control girls matched for chronological age (patients 0.575 +/- 0.097 g/cm2, controls 0.433 +/- 0.049 g/cm2, P < 0.001). Patient BMD was not significantly different from that of ten control girls matched according to patient bone, age (0.550 +/- 0.046 g/cm2, P = NS). During GnRH-a treatment, pituitary-gonadal axis was suppressed and patient BMD significantly decreased (6 months: -6.0%, P < 0.002 vs baseline; 12 months: -8.0%, P < 0.001 vs baseline). We conclude that in girls with precocious puberty the activation of gonadal steroid secretion induces an increase in bone mineralization and that oestrogen deprivation by GnRH-a treatment caused a significant decrease in BMD.

Topical application of 1,25-dihydroxyvitamin D3 (calcitriol) is an effective and reliable therapy to cure skin lesions in psoriatic children

We studied, in vivo, the effects of a calcitriol-containing ointment (3 micrograms of calcitriol per gram of petrolatum) topically applied on skin lesions in children affected by psoriasis vulgaris. Each patient was instructed to apply the ointment, about 1 g once a day at bedtime followed by occlusive dressing with plastic wrap, on one-side lesion (treated) and petrolatum alone on the equivalent controlateral site (placebo) (total weekly dose of calcitriol: approximately 21 micrograms/patient). After 4 weeks of topical treatment all children showed a complete clearing of their skin lesions on the treated side, without appreciable changes on the placebo side. Serum ionised calcium, calcium and calcitriol levels or urinary calcium excretion did not vary significantly throughout the period of therapy. These findings suggest that topical calcitriol may be an effective and safe alternative therapy for psoriasis in children.

Growth velocity and serum aminoterminal propeptide of type III procollagen in precocious puberty during gonadotropin-releasing hormone analogue treatment

Growth velocity and serum aminoterminal propeptide of type III procollagen (P-III-NP) were evaluated in 11 girls (age 3.8-8.5 years) with central precocious puberty during luteinizing hormone releasing hormone (LH-RH) analogue treatment (D-Trp6-LH-RH, 60 micrograms/kg im for 28 days, n = 7; D-ser(TBU)6-LH-RH, 1600 micrograms/day intranasally, n = 4). Before treatment, growth velocity (10.2 +/- 1.9 cm/year) and P-III-NP concentrations (12.8 +/- 4.3 micrograms/l) were in the pubertal range. During therapy, growth velocity significantly decreased to the prepubertal levels. P-III-NP concentrations decreased significantly after six months of therapy (7.9 +/- 3.7 micrograms/l, p < 0.001). Three girls with low growth velocity ( < 4 cm/year), stimulated growth hormone peak < 10 micrograms/l, and altered 12-h nocturnal growth hormone secretion at 12 and/or 18 months of treatment, had a more marked decrease in P-III-NP concentrations (patient 3: -65.9%; patient 5: -58.7%; patient 10: -61.0%) after 6 months of therapy. Our results suggest that LH-RH analogue treatment in central precocious puberty may impair growth. In these cases, measurement of serum P-III-NP levels may be an additional marker to monitor growth.

Induction of Calbindin-D28K by 1,25-dihydroxyvitamin D3 in cultured chicken intestinal cells

Intestinal cells from chicken embryos were grown in chemically defined, serum-free medium. The majority of cultured cells exhibits an epithelial-like morphology. As demonstrated by indirect immunofluorescence, the epithelial cells, and not the contaminating fibroblasts, express Calbindin-D28K only after 1,25-dihydroxyvitamin D3, the hormonally active form of vitamin D, is added to the culture medium. The highly sensitive reverse transcriptase-polymerase chain reaction shows that both Calbindin-D28K mRNA and the corresponding primary unprocessed transcripts (pre-mRNA) are dramatically increased in cultured intestinal cells treated with 1,25-dihydroxyvitamin D3, thus indicating that Calbindin-D28K is induced by the increased rate of transcription of the corresponding gene.

Differentiation-dependent expression of apolipoprotein A-I in chicken myogenic cells in culture

Northern blot hybridization experiments showed that Apolipoprotein A-I (Apo A-I) mRNA is present at high concentration in chicken myotubes cultured in vitro, while it is virtually absent in fibroblasts and myoblasts. Myotubes are also capable of translating and secreting in the culture medium a protein which is specifically immunoprecipitated by anti-Apo A-I antibodies and has the same electrophoretic mobility as Apo A-I purified from circulating high-density lipoproteins. The appearance of Apo A-I mRNA in myotubes depends on the transcriptional activation of the corresponding gene, as it was shown by hybridizing 32P-labeled RNA synthesized in isolated nuclei to Apo A-I cDNA. The activation of the Apo A-I gene is regulated by the muscle cell coordinately with muscle-specific genes. In fact, treatment with TPA, a powerful inhibitor of differentiation, efficiently prevents myoblasts from producing Apo A-I mRNA, as well as muscle actin mRNA, and causes myotubes to quickly cease Apo A-I mRNA synthesis. The existence of a strict relationship between Apo A-I mRNA concentration and myogenic cell differentiation was also confirmed by experiments with quail myoblasts transformed with a temperature-sensitive mutant of the Rous Sarcoma Virus. Cells raised at the permissive temperature (undifferentiated phenotype) do not contain Apo A-I as well as alpha-actin mRNAs, while shifting to the nonpermissive temperature (differentiated phenotype) causes a rapid increase in Apo A-I and alpha-actin mRNA concentration.

Identification of chicken calbindin D28K pre-messenger RNA sequences by polymerase chain reaction

A transcribed RNA sequence encompassing the junction between the first intron and the second exon of the chicken calbindin D28K gene was copied in a cDNA fragment and subsequently amplified by polymerase chain reaction. When intestinal RNA is used as template, the appearance of the 161 bp amplified fragment is strictly dependent on the vitamin D status of the animal. In fact no amplified fragment is obtained when the RNA is extracted from the intestine of vitamin D-deficient chickens, while it is easily detected when the RNA is extracted only 30 min after injection with 1,25-dihydroxycholecalciferol. Conversely, the amplified fragment is obtained, irrespectively of the vitamin D status of the animal, when the RNA template is extracted from the brain. The appearance of unspliced RNA sequences upon vitamin D induction is followed, after a 30 min lag, by the appearance of the corresponding mature mRNA sequences.

Expression and secretion of chicken apolipoprotein AI in transfected COS cells

A full-length chicken apolipoprotein A-I (apoAI) cDNA has been cloned into an expression vector, pRSVapoAI. This plasmid was transfected into a monkey kidney (COS-1) cell line in order to study apolipoprotein-lipid assembly. Chicken apoAI is the major apolipoprotein of chicken high-density lipoprotein (HDL), which is less complex in apolipoprotein content than the HDL of human plasma. The transient transfected COS-1 cells synthesized and secreted authentic plasma apoAI. Under serum-free medium conditions, COS cells secreted only proapoAI. A small portion (15%) of the secreted apoAI floated at a density 1.07-1.20 g/ml. Upon incubation with fetal bovine serum at 10 degrees C, a majority of the apoAI was recovered in the HDL density (1.06-1.20 g/ml) region. Secreted apoAI was labeled when transfected COS cells were incubated with [U-14C]palmitate, but the incorporation of radioactivity was not the result of fatty acid acylation through ester bond formation. These results indicate that heterologous COS-1 cells are capable of synthesizing and secreting apoAI, and that intracellular association of apoAI with lipids is not necessary for secretion.