Structure and function of protamines: an 1H nuclear magnetic resonance investigation of the interaction of clupeines with mononucleotides.

Protamines form a class of low-molecular-weight proteins that protect the chromosomal DNA in the spermatic cells of eukaryotic organisms. Protamines are located in the small and/or large groove of DNA where they complex the DNA nucleotides. Very little is known up to date on the role and specificity of binding of the various protamine fractions belonging to a single eukaryotic species. In the present paper, a detailed investigation on the complexation properties of the protamine fractions (clupeines) extracted from herrings has been carried out by means of proton nuclear magnetic resonance and ultraviolet absorbtion data. In particular, the binding properties of the clupeine fractions with purinic (5'dAMP) and pyrimidinic (5'dCMP) mononucleotides have been measured and analysed at different clupeine concentrations. The results indicate that, contrary to previous preliminary hypothesis, the three clupeine fractions exhibit quite comparable binding properties toward mononucleotides. In addition it has been found that nucleotides can induce a conformational transition of the disorder-order type in the clupeine molecules and this property is concentration and temperature dependent. It is concluded that, as far as specificity is concerned, the clupeine fractions seem to possess the same behaviour toward mononucleotides.

A physico-chemical approach to the study of the binding interaction between S-adenosyl-L-methionine and polyanions: binding constants and nature of the interaction with sodium poly(styrene sulfonate).

The interaction between S-adenosyl-L-methionine (AdoMet) and sodium poly(styrene sulfonate) NaPSS) was studied by means of ultrafiltration and ultraviolet absorption spectroscopy at several pH values and sodium sulfate concentrations. The results obtained are interpreted mainly in terms of electrostatic interactions and permit the evaluation of the binding constants under different experimental conditions. Furthermore, ultraviolet absorption spectroscopy data show a specific short-range interaction between the aromatic electronic system of AdoMet and the NaPSS aromatic ring. The results indicate that the binding strength is greatly affected by the AdoMet positive charge on the adenine ring. The other positive charges on both the sulfonic pole and the amino acidic group of AdoMet contribute only weakly to the binding to the polyanionic matrix, thus assuring some stability of AdoMet even at physiological pH.

Plasminogen activator inhibitor type-1: reactive center and amino-terminal heterogeneity determined by protein and cDNA sequencing.

Both the urokinase-type and tissue-type plasminogen activator can convert their approximately 54 kDa type-1 inhibitor (PAI-1) to an inactive form with a lower apparent molecular mass. We have determined the amino-terminal amino acid sequences of human native and converted PAI-1, and isolated PAI-1 cDNA and determined the nucleotide sequence in regions corresponding to the amino-terminus and the cleavage site. The data show that the conversion of the inhibitor consists of cleavage of an Arg-Met bond 33 residues from the carboxy-terminus, thus localizing the reactive center of the inhibitor to that position. In addition, a heterogeneity was found at the amino-terminus, with a Ser-Ala-Val-His-His form and a two-residue shorter form (Val-His-His-) occurring in approximately equal quantities.

Megalocornea and mental retardation syndrome: two new cases.

We report on 2 patients with the Neuhäuser megalocornea-mental retardation syndrome, a recessively inherited clinical entity of relatively recent description (McKusick 24931). A review of the few previous reported patients and our 2 patients shows that megalocornea and mental retardation are the 2 minimal diagnostic criteria. Short stature, seizures, neurological symptoms, microcephaly or macrocephaly, and minor anomalies are all additional nonobligatory manifestations. The small number of published cases may be due to the fact that the association of these two signs has often escaped attention until now.

Early signs of vascular disease in homocystinuria: a noninvasive study by ultrasound methods in eight families with cystathionine-beta-synthase deficiency.

Fourteen patients (six males, eight females; mean age, 20 years) with homocystinuria due to homozygous cystathionine-beta-synthase (CBS) deficiency, underwent a vascular examination. Fourteen heterozygotes (seven males, seven females; mean age, 46 years), including 12 parents and one daughter of homozygotes (obligate heterozygotes), and one sister of a homozygote (with low enzyme activity as evaluated in vitro), were also examined. Homozygotes and heterozygotes were compared with two separate control groups of different age (mean age, 20 and 43 years, respectively). Ankle/arm systolic pressure index (by continuous-wave Doppler) was, on average, lower in homozygotes (P less than .01) and heterozygotes (P less than .05) as compared with the controls. An ankle/arm index less than 0.97 and suggesting flow-reducing arterial lesions was found in six (21%) lower limbs of homozygotes versus zero in controls (P less than .05). Echo Doppler (Duplex Scanner) abnormalities, indicating early, non-flow-reducing lesions of iliac arteries were more frequent in homozygotes (seven wall abnormalities or stenoses less than 15%) than in young controls (P less than .05). The corresponding figures for heterozygotes were seven wall abnormalities or stenoses (1% to 15% and one stenosis 16% to 50%) (P less than .01 v middle-aged controls). Early lesions (three wall abnormalities or stenoses less than 15%, three stenoses 16% to 50%) were detected in six (23%) internal carotids of heterozygotes versus three (3%) of corresponding controls (P less than .05). Technical limitations precluded the accurate detection of early lesions in the internal carotid arteries of young homozygotes and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Stiffness of the aortic wall in hypercholesterolemic children.

Arterial stiffness may be an indicator of early vascular changes signaling the development of vascular disease, while hypercholesterolemia is a well-recognized promoter of atherogenesis. It has been shown that hypercholesterolemic children have a thicker intima-media in the carotid artery than children with normal cholesterol. The aim of this study was to assess the stiffness of the abdominal aorta in children with hypercholesterolemia. Noninvasive imaging evaluation of the aorta was performed in 85 outpatient children (age, 3 to 14 years) with and without high cholesterol levels ((and) 247 mg/dL [6.4 mmol/L], respectively). Ultrasound imaging of the abdominal aorta that allowed diameter measurements was available in 67 children. Using an image-processing workstation, the maximum and minimum internal diameter of the aorta was measured, and the following indices of elastic properties of the abdominal aorta were derived: arterial strain, pressure-strain elastic modulus, and stiffness. No statistical difference for aortic strain, stiffness, and elastic modulus was found in normocholesterolemic compared with hypercholesterolemic children. The effect of age on the elastic modulus was different in the two groups: in normal children, the elastic modulus increased linearly with age (y = -0.020+0.003 x age [months], P<.001), while the high-cholesterol group had a weak increase in this parameter with age (y = 0.118+0.0009 x age, P = .051). The slope of the regression equations (elastic modulus vage) was significantly different in the two groups (t = 2.45, P = .017). The behavior of arterial stiffness with respect to age was similar, y = 0.677+0.018 x age (P = .002) in normocholesterolemic children and y = 2.06+0.00198 x age (P = .66) in hypercholesterolemic children. The slope of the regression equations (stiffness v. age) was significantly different in the two groups (t = 2.37, P = .021). The present study demonstrates an influence of hypercholesterolemia on age-related modification in the elastic properties of the aorta. A remodeling of the aortic wall in hypercholesterolemic children (cholesterolemia >247 mg/dL) could explain the different age-dependent increase in aortic elastic modulus and stiffness.

Protein-bound plasma homocyst(e)ine and identification of heterozygotes for cystathionine-synthase deficiency.

We measured protein-bound plasma homocyst(e)ine in 15 normal adult subjects and nine heterozygotes for homocystinuria due to cystathionine beta-synthase deficiency. The mean (+/- SD) concentrations obtained in the two groups of subjects were 4.35 +/- 1.50 and 9.16 +/- 3.40 mumoll-1, respectively. The mean values were significantly different, although the levels of three heterozygotes overlapped those of the control range. This method allows preliminary screening of the heterozygotes for homocystinuria and can be carried out by laboratories that have only facilities for amino acid analysis.

Variable clinical presentation of carbonic anhydrase deficiency: evidence for heterogeneity?

The clinical and biochemical findings in an Italian sibship affected by carbonic anhydrase II deficiency are described. Evidence of clinical heterogeneity and an increased frequency of the disease in the Mediterranean area and the Middle East are discussed.

A simplified test to detect PKU heterozygotes by discriminant analysis in mentally retarded children and their mothers.

We have developed classification coefficients and an equation to detect heterozygotes for phenylketonuria. The combination of several variables (Phe, Phe/Tyr, Phe2/Tyr) gave a safe diagnosis in more than 96% of cases. We then computerized a random selection of our population, which was divided into two groups: the first was "selected" to compute discriminant functions, while the second, excluded from computation, was used to check the fitness of our method. Despite the reduction of sample size, 95.2% of unknown subjects were correctly classified. Finally, we used our equation to detect heterozygotes for phenylketonuria in a population of 26 children, affected by non-specific mental retardation, and their mothers. We found a high proportion of carriers for phenylketonuria, defined as subjects having a percent probability of correct classification higher than 90. By this method, heterozygosity was detected in two child-mother couples, four individual children and five mothers.

Analysis of the influence of coupled diffusion on transport in protein crystal growth for different gravity levels.

Diffusion has a central role in protein crystal growth both in microgravity conditions and on ground. Recently several reports have been focused on the importance to use the generalized Fick's equations in n-component systems where crystals grow. In these equations the total flux of each component is produced by the own concentration gradient (main flow) and by the concentration gradient of the other components (cross-flow) present in the system. However in literature the latter effect is often neglected, and the so-called pseudo-binary approximation is used. Lin et al. (1995) proposed a mathematical model to evaluate the concentration profile of the species present around a growing protein crystal. Although the model is reliable, it suffers of the pseudo-binary approximation (neglecting cross term diffusion coefficients and using binary diffusion coefficients), probably because of the lack of multicomponent diffusion data. The present model is based on the experimental set-up proposed by Lin et al. (1995). Nevertheless we have included the coupled diffusion effects, according to the correct description of the matter transport through the generalized Fick's equations. The crystal growth rate is calculated for different gravity levels. The model has been applied to the ternary lysozyme-NaCl-water and quaternary lysozyme-poly(ethylene glycol) (PEG)-NaCl-water systems using recent diffusion data.

[Bone changes in homocystinuria in childhood]. / Le alterazioni scheletriche dell'omocistinuria in età pediatrica.

Homocystinuria due to cystathionine synthase deficiency is an autosomal recessive error of sulphur amino acid metabolism characterized clinically by lens dislocation, mental retardation, skeletal abnormalities and thromboembolic phenomena. We have evaluated roentgenologically our series of 12 pediatric homocystinuric patients to detect skeletal abnormalities. Bone changes are widespread and occur mainly in dorsolumbar spine and in epi-metaphyseal growth areas. Osteoporosis is the most important finding. Dolichostenomelia and arachnodactily are relatively common. Calcific spicules occur frequently in the wrist physes.

Increased intima-media thickness of the common carotid artery in hypercholesterolemic children.

Common carotid intima-media thickness was measured by B-mode ultrasound imaging in 46 children (mean age, 7.4 years) with serum cholesterol > or = 6.4 mmol/L (mean, 8.25 mmol/L) and in 48 children (mean age, 6.4 years) with serum cholesterol < 6.4 mmol/L (mean, 4.60 mmol/L). Maximum thickness was significantly higher in hypercholesterolemic children than in control children (0.50 versus 0.47 mm, P = .007). Subgroup analysis showed that only in children > 6.2 years old (the median of all the children's ages) was maximum thickness significantly higher in hypercholesterolemic children than in control children (0.51 versus 0.48 mm, P = .014). The odds ratio (OR) of common carotid intima-media thickening (maximum thickness of the far wall higher than the 95th percentile of the control group, 0.51 mm) between patients and control subjects was statistically significant both in univariate analysis (OR, 6.39; 95% confidence interval, 1.19 to 32.3; P = .025) and after age (OR, 5.96; 95% confidence interval, 1.09 to 32.4; P = .039) and sex (OR, 7.54; 95% confidence interval, 1.38 to 41.2; P = .020) were controlled for. Children > 6 years old with serum cholesterol > or = 6.4 mmol/L show increased thickness of the common carotid intima-media.

The regulatory region of the human plasminogen activator inhibitor type-1 (PAI-1) gene.

The human gene for plasminogen activator inhibitor type-1 (PAI-1) has been isolated and its promoter region characterized. PAI-1 regulation by glucocorticoids, transforming growth factor-beta (TGF-beta) and the phorbol ester PMA is shown to be exerted at the promoter level. A fragment spanning 805 nucleotides of the 5' flanking and 72 of the 5' untranslated region contain information enough to promote transcription and to respond to glucocorticoids when fused to a reporter gene and transfected into human fibrosarcoma cells. A moderately repetitive DNA sequence, containing a TATA box, a GRE consensus, a Z-DNA forming sequence and two imperfect direct repeats at the extremities, is present a few nucleotides 5' of the human PAI-1 gene transcription start site, raising the possibility that this gene could have been activated by DNA insertion during evolution.

Control of lactase in human adult-type hypolactasia and in weaning rabbits and rats.

Lactase is an enterocyte brush-border membrane beta-glycosidase that splits lactose, the sugar of milk. In mammals, including many human populations, intestinal lactase activity is very high in the suckling and declines to low levels after weaning. There are two human adult lactase phenotypes, one in which high lactase activity persists and another in which it declines. Two alleles have been postulated to explain these different phenotypes. In the present study lactase mRNA levels have been investigated in the small intestine (a) of rabbits and rats, at different ages, considered as models for mammals, and (b) of human adults with the two lactase phenotypes. In rabbits and rats, high levels of lactase mRNA are present up to the weaning period, a time at which a consistent decrease of this mRNA is found, a decrease that parallels that of lactase activity. It is surprising that after this period adult animals of both species express again high levels of lactase mRNA, whereas lactase activity remains at very low levels. Our results suggest that in the adult rabbits and rats the main control of lactase gene expression is likely to be at a posttranscriptional level. Similarly, in man no clear difference was found at the RNA level between adults with hypolactasia and adults with persistent high lactase activity, a result that also indicates a posttranscriptional control of lactase expression.

Vaccination against hepatitis B in preschool children with Down's syndrome.

Twenty-nine healthy HBsAg- and HBsAb-negative children with Down's syndrome who were living at home (mean age 42 months; 19 M, 10 F) were vaccinated against hepatitis B virus either with recombinant DNA or plasma-derived vaccine. Both groups of children responded well to the vaccination schedules, with HBsAb seroconversion rates close to 100%. Vaccination against hepatitis B in preschool children with Down's syndrome is effective in spite of the existing abnormalities of the immune function.

Plasminogen activator inhibitor type 1 gene is located at region q21.3-q22 of chromosome 7 and genetically linked with cystic fibrosis.

The regional chromosomal location of the human gene for plasminogen activator inhibitor type 1 (PAI1) was determined by three independent methods of gene mapping. PAI1 was localized first to 7cen-q32 and then to 7q21.3-q22 by Southern blot hybridization analysis of a panel of human and mouse somatic cell hybrids with a PAI1 cDNA probe and in situ hybridization, respectively. We identified a frequent HindIII restriction fragment length polymorphism (RFLP) of the PAI1 gene with an information content of 0.369. In family studies using this polymorphism, genetic linkage was found between PAI1 and the loci for erythropoietin (EPO), paraoxonase (PON), the met protooncogene (MET), and cystic fibrosis (CF), all previously assigned to the middle part of the long arm of chromosome 7. The linkage with EPO was closest with an estimated genetic distance of 3 centimorgans, whereas that to CF was 20 centimorgans. A three-point genetic linkage analysis and data from previous studies showed that the most likely order of these loci is EPO, PAI1, PON, (MET, CF), with PAI1 being located centromeric to CF. The PAI1 RFLP may prove to be valuable in ordering genetic markers in the CF-linkage group and may also be valuable in genetic analysis of plasminogen activation-related diseases, such as certain thromboembolic disorders and cancer.