Mammalian DNA polymerase alpha: a replication-competent holoenzyme form from calf thymus

Calf thymus DNA polymerase alpha, like the replication-specific DNA polymerase III holoenzyme of Escherichia coli, can be isolated as a distinct complex. A specific multiprotein form of the polymerase alpha, a form designated replication-competent (RC) holoenzyme, consists of a complex of a polymerase-primase core and at least six other polypeptides. The RC holoenzyme can efficiently replicate several naturally occurring templates, including the genomic DNA of the porcine circovirus (PCV). The DNA of this virion consists of a single-stranded circle with a defined replication origin, and its replication requires the cellular DNA replication machinery. It might therefore provide an invaluable opportunity to investigate chromosomal replication mechanisms, analogous to the way that studies on E. coli bacteriophage DNA replication elucidated host DNA replication mechanisms. Calf RC holoenzyme alpha selectively initiates PCV DNA replication in vitro at a site that possibly represents a consensus sequence of cellular DNA replication origins. The cell-free PCV replication system will be exploited for the in vitro dissection and reconstitution of the RC holoenzyme and the functional analysis of its component polypeptides.

Increased plasma apolipoprotein B levels and blood hyperviscosity in non-insulin-dependent diabetic patients: role in the occurrence of arterial hypertension

An association between arterial blood pressure and blood viscosity has been suggested in healthy and in diabetic subjects, and that the hemorheological pattern may be influenced by blood lipid alterations. In diabetic patients a relationship between arterial hypertension and blood lipid changes may therefore be suggested. This study concerns 19 type II diabetics with hyperlipidemia (triglycerides = 3.2 +/- 1 mmol/l; total cholesterol = 6.1 +/- 1.2 mmol/l; HDL-cholesterol = 0.92 +/- 0.27 mmol/l; VLDL = 29 +/- 5%) (group A), and 19 normolipidemic type II diabetics (triglycerides = 1.15 +/- 0.5 mmol/l; total cholesterol = 5.1 +/- 1 mmol/l; HDL-cholesterol = 1.25 +/- 0.38 mmol/l; VLDL = 20 +/- 5%) (group B). No differences concerning age, body weight, duration of diabetes and glycemic control were found in hyperlipidemic compared to normolipidemic diabetics. On the contrary, higher systolic and diastolic blood pressure levels were demonstrated in group A (167 +/- 14 mmHg and 101 +/- 5.2 mmHg, respectively) than in group B (144 +/- 15 mmHg, p less than 0.001 and 87 +/- 6.9 mmHg, p less than 0.001, respectively). An increase of plasma apolipoprotein B level (163 +/- 27 mg/dl vs 102 +/- 21 mg/dl, p less than 0.001), of plasma viscosity (1.81 +/- 0.08 mPas vs 1.51 +/- 0.07 mPas, p less than 0.001) and of blood viscosity (5.37 +/- 0.33 mPas vs 5.07 +/- 0.04 mPas, p less than 0.01, at shear-rate of 90 s-1; 18.4 +/- 1 mPas vs 14.1 +/- 0.9 mPas, p less than 0.001 at shear-rate of 2.25 s-1) was found in group A, compared to group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning of Bacillus subtilis genes involved in DNA metabolism

Different clones carrying a chromosomal DNA fragment able to transform Bacillus subtilis mutants dnaA13, dnaB19, dnaG5, recG40 and polA42 to a wild-type phenotype were isolated from a library constructed in plasmid pJH101. A lambda recombinant clone carrying a chromosomal fragment able to transform dnaC mutants was obtained from a lambda Charon 4A library. A restriction map of the cloned DNA fragments was constructed. The 11.3 kb cloned DNA fragment of plasmid pMP60-13 containing the wild-type sequence of dnaG5 was shown to transform a recF33 mutant as well.

Pentoxifylline, total urinary protein excretion rate and arterial blood pressure in long-term insulin-dependent diabetic patients with overt nephropathy

A specific hemorheologic treatment might reduce urinary protein excretion and the decline in kidney function in diabetic patients with overt clinical nephropathy. Twenty-one insulin dependent (type I) diabetic patients were randomized and assigned to a treatment with conventional antihypertensive therapy (protocol I) or with pentoxifylline (Trental 400) (protocol II). A marked improvement of blood rheology pattern, together with a reduction of urinary albumin excretion rate and total urinary protein excretion rate, was demonstrated throughout a 1-year follow-up study with pentoxifylline. Furthermore a decrease of systolic and diastolic blood pressure levels was found during the treatment. The modification of these parameters was followed by a significant increase of creatinine clearance in each of the patients studied. The results obtained during pentoxifylline therapy were comparable to those obtained in patients treated with conventional antihypertensive drugs. Pentoxifylline may therefore be used in the treatment of advanced nephropathy in diabetic patients.

Plasma fibronectin as an indicator of microvascular damage in diabetic patients. Rapid and sensitive evaluation by a radial immunodiffusion technique

Plasma fibronectin might be considered as an indicator of early and advanced microvascular damage in diabetic patients. We have therefore studied plasma fibronectin, using a radial immunodiffusion technique (LC-Partigen Fibronectin), in insulin-dependent and non-insulin-dependent diabetic patients with and without microangiopathic and neurological complications, i.e. retinopathy, nephropathy and autonomic and peripheral neuropathy. Steady and progressive increases of plasma fibronectin levels in association with the worsening of both diabetic retinopathy and nephropathy have been observed. However, significant variations of plasma fibronectin levels were already found in diabetic patients without microangiopathy when compared with healthy control subjects. Fibronectin levels were also higher in diabetic patients with autonomic and peripheral neuropathy than in control subjects and diabetic patients without neurological changes. The evaluation of plasma fibronectin by a specific radial immunodiffusion procedure might represent an important approach in the study and prevention of diabetic microcirculatory disorders.

Characterization of the levanase gene of Bacillus subtilis which shows homology to yeast invertase

The structural gene for the enzyme levanase of Bacillus subtilis (SacC) was cloned in Escherichia coli. The cloned gene was mapped by PBS1 transduction near the sacL locus on the B. subtilis chromosome, between leuA and aroD. Expression of the enzyme was demonstrated both in B. subtilis and in E. coli. The presence of sacC allowed E. coli to grow on sucrose as the sole carbon source. The complete nucleotide sequence of sacC was determined. It includes an open reading frame of 2,031 bp, coding for a protein with calculated molecular weight of 75,866 Da, including a putative signal peptide similar to precursors of secreted proteins found in Bacilli. The apparent molecular weight of purified levanase is 73 kDa. The sacC gene product was characterized in an in vitro system and in a minicell-producing strain of E. coli, confirming the existence of a precursor form of levanase of about 75 kDa. Comparison of the predicted aminoacid sequence of levanase with those of the two other known beta-D-fructofuranosidases of B. subtilis indicated a homology with sucrase, but not with levansucrase. A stronger homology was detected with the N-terminal region of yeast invertase, suggesting the existence of a common ancestor.

Determination of albuminuria in type 1 and type 2 diabetic patients with microproteinuria and overt nephropathy. Comparative evaluation between a radial immunodiffusion procedure and a highly sensitive radioimmunoassay

We have studied the correlation between urinary albumin excretion rate evaluated by a radial immunodiffusion technique and a highly sensitive radioimmunoassay in type 1 and type 2 diabetic patients with microproteinuria and overt clinical nephropathy. Several statistically significant correlations were found between urinary albumin excretion rate measured by radial immunodiffusion and by radioimmunoassay, both in patients with microproteinuria and overt nephropathy. Moreover, statistically significant correlations between urinary albumin excretion rate, albumin clearance and total urinary protein excretion rate were observed in each of the groups studied. The radial immunodiffusion procedure can therefore be considered a useful and sensitive method for the evaluation of urinary albumin excretion rate both in diabetic patients with microproteinuria and in patients with overt clinical nephropathy.

Nucleotide sequence of the outB locus of Bacillus subtilis and regulation of its expression

The outB gene is one of the genes involved in the process of spore outgrowth in Bacillus subtilis. The gene has been cloned in bacteriophage lambda and subcloned in plasmids. We have determined the sequence of 2,553 base pairs around the outB locus. The locus was found to code for a protein of about 30,000 daltons. Analysis of the in vivo transcripts from this region by RNase protection experiments revealed the presence of two start sites for transcription. Two potential promoters for these transcripts can be tentatively assigned from the sequence data. The amount of one transcript is highest during outgrowth and vegetative growth and absent during the stationary phase. The second transcript is present at a low level throughout the cell cycle.

Circulating opioids and plasma renin activity in insulin-dependent diabetics with renal haemodynamic alterations

Circulating opioids were studied in insulin-dependent diabetics with renal haemodynamic alterations. Higher circulating beta-endorphin (beta-EP) and lower beta-lipotropin (beta-LPH) levels were found in patients with glomerular hyperfiltration than in diabetics with normal glomerular filtration rate (GFR) and controls. Moreover, significantly positive correlations between beta-EP and GFR, and between beta-EP and renal plasma flow were demonstrated in these patients. On the contrary, reduced beta-EP levels were observed in diabetics with impaired GFR and overt nephropathy. Plasma renin activity was increased in diabetics with glomerular hyperfiltration and reduced in diabetics with overt nephropathy. Circulating opioids might, therefore, play a role in renal haemodynamic alterations, both in patients with early and advanced glomerular changes.

Characterization and mapping of the Bacillus subtilis prtR gene

A gene from Bacillus natto encoding a 60-amino-acid peptide has been previously described that, when cloned on a high-copy plasmid in B. subtilis, enhances production of alkaline protease, neutral protease, and levansucrase. An identical gene was isolated from B. subtilis and caused a similar phenotype when placed on a high-copy plasmid. Genetic mapping localized this gene near metB, distant from other pleiotropic genes causing similar effects. Deletion of this gene from the B. subtilis chromosome had no obvious phenotypic effect.

Cloning and expression of a cDNA encoding a catalytically active fragment of calf thymus DNA polymerase alpha

A calf thymus cDNA expression library was constructed in the EcoRI site of lambda gt11 and probed with an antibody raised against calf thymus DNA polymerase alpha. Three classes of antibody-reactive clones were isolated. The largest class carried a 1.9 kilobase calf cDNA insert and expressed a 165-175 kilodalton beta-galactosidase:calf fusion protein which displayed DNA polymerase activity. The characteristic responses of the polymerase activity to alpha-specific inhibitors and antibodies identified the 1.9 kilobase cDNA as a sequence specifically derived from the structural gene encoding the pol alpha catalytic core.

Pentoxifylline, albumin excretion rate and proteinuria in type I and type II diabetic patients with microproteinuria. Results of a short-term randomized study

An association between renal microvascular complications and hemorheological alterations has been suggested in diabetes mellitus. Therefore, a hemorheologic approach in the treatment of diabetic microproteinuria has been proposed. Eighty-two type I and type II diabetic patients with microproteinuria were randomized and assigned to two different protocols: protocol A, patients treated with pentoxifylline (Trental 400); protocol B, patients without hemorheologic treatment, in whom hypoglycemic therapy was just more strictly enforced. A significant improvement of the hemorheologic pattern and a significant marked reduction of albumin excretion rate and proteinuria was found in diabetic patients treated with pentoxifylline, independently of the degree of metabolic control. These results were readily achieved and were confirmed throughout the study. Moreover, these results were comparable to those obtained in diabetic patients of protocol B. Pentoxifylline might therefore be considered as the first useful therapeutic agent in the treatment of diabetic microproteinuria.

Effect of stage 0 sporulation mutations on subtilisin expression

Subtilisin expression as a function of growth and sporulation was determined using a presubtilisin-beta-galactosidase gene fusion. An approximately 500-base-pair region upstream of the subtilisin gene and including the first eight codons of the presubtilisin protein was fused at the eighth codon of beta-galactosidase in the integrative vector pJF751. This gene fusion does not carry a signal sequence, and therefore its synthesis is uncoupled from maturation of presubtilisin. The fusion protein gene was integrated into a variety of recipient strains to test for the effect of various mutations on the initial rate of presubtilisin-beta-galactosidase synthesis. Among the spo0 mutations tested, the spo0A mutations showed a strong, 10-fold decrease in the rate of beta-galactosidase synthesis. This effect of the spo0A mutations was not evident when the presubtilisin-beta-galactosidase fusion was present on a multicopy plasmid. The sacU mutation, which was known to increase the extracellular level of levansucrase and proteases, was found to increase the synthesis of the presubtilisin-beta-galactosidase gene fusions 7-fold, and the hpr mutations were shown to increase the rate of presubtilisin-beta-galactosidase gene fusions 17-fold, indicating that these mutations influence either transcription or translation of the presubtilisin gene. However, the effect of these mutations was only observed in the stationary phase of growth, indicating they did not render synthesis constitutive. By using multicopy plasmids and an integrated gene fusion, it was shown that there is likely to be a titratable repressor controlling subtilisin synthesis.

Identification of the pleiotropic sacQ gene of Bacillus subtilis

The sacQ gene of Bacillus subtilis, a pleiotropic gene affecting the expression of a number of secreted gene products, has been identified as a small 46-amino-acid polypeptide. The increased expression of this polypeptide in strains carrying the sacQ36 allele, or in strains carrying the sacQ gene on a high copy plasmid, appears to be responsible for the phenotype of higher levels of proteases seen in these strains. A deletion of the sacQ gene had no apparent phenotype, indicating that it is not an essential gene.

Cytochemistry of circulating lymphocytes in diabetes mellitus with and without retinopathy and in newly diagnosed type I (insulin dependent) diabetes

Cytochemical studies have been performed on peripheral blood lymphocytes of 68 diabetic subjects, with various conditions of metabolic control, and 15 newly diagnosed insulin-dependent diabetic patients. 20 patients of the 1 group had diabetic retinopathy. In diabetic patients periodic acid Schiff positivity, acid phosphatase, and N-acetyl-beta-glucosaminidase activities of lymphocytes are fairly impaired, particularly in insulin-dependent diabetes. Concerning the alpha-naphthyl-acetate-esterase activity, the percentage of positive cells with coarse granules is significantly reduced (p less than 0.001) in diabetic patients as compared to controls, without difference related to age and sex. These abnormalities are more evident in patients with poor glyco-metabolic control. In patients with newly diagnosed insulin-dependent diabetes we have found a further decrease in alpha-naphthyl-acetate-esterase activity, and an increase in acid phosphatase and N-acetyl-beta-glucosaminidase activities. Cyto-enzymatic activities are not significantly different in subjects with diabetic retinopathy. The results of peripheral lymphocyte enzymatic activities in diabetics could be related to a depression of the cell-mediated immunity and could enhance the infections risk of these patients. Furthermore our data show an altered immunological balance in subjects with newly diagnosed type I diabetes.

Molecular cloning of a Bacillus subtilis gene involved in spore outgrowth

A lambda Charon 4A derivative carrying the outB gene of Bacillus subtilis has been identified by transformation of a B. subtilis mutant temperature-sensitive in spore outgrowth. The cloned region is a single EcoRI fragment 14 kb in length. In addition to outB, the cloned DNA includes at least part of the amyE and aroI loci.

Plasma fibronectin, von Willebrand factor antigen, and blood rheology. Association with diabetic microvascular disease

Plasma fibronectin might play a role in the pathogenesis and progression of diabetic microvascular disease. To test this hypothesis we measured plasma fibronectin, von Willebrand factor antigen, fibrinogen, erythrocyte filtrability, whole-blood viscosity, proteinuria and albuminuria in 25 control subjects and 29 diabetic patients with and without microvascular complications. Plasma fibronectin was significantly higher in the diabetic patients, especially in those with retinopathy and nephropathy. A significant correlation between fibronectin and von Willebrand factor antigen was found in both patients with and without microangiopathy (p less than 0.001). In diabetic patients with and without microvascular complications, several significant correlations were found between increased fibronectin levels and reduced erythrocyte filtrability (p less than 0.001) and between the increase of fibronectin and whole-blood viscosity (p less than 0.001). Furthermore, a significant correlation was found between plasma fibronectin levels, proteinuria (p less than 0.001) and albuminuria (p less than 0.001). The relationship between plasma fibronectin and changes of blood rheology may be important for the occurrence and progression of diabetic microangiopathy.

Characterization of the spo0A locus and its deduced product

The highly pleiotropic stage 0 sporulation locus of Bacillus subtilis, spo0A, has been cloned in bacteriophage lambda, subcloned in plasmids, and sequenced. The locus was found to code for a protein of 29,691 Da. Analysis of the in vivo transcripts from this region by nuclease S1 protection experiments located the start and stop of transcription of the locus. The transcription start site was preceded by a promoter resembling sigma 37-dependent promoters. Two mutations originally assigned to a second locus, spo0C, in this region because of their weakly pleiotropic phenotypes were cloned and sequenced. The mutations were found to be different missense alterations in the same base of the 10th codon preceding the carboxyl end of the Spo0A protein. These results, along with the finding that mutations in the spo0A gene product [Hoch, J. A., Trach, K., Kawamura, F. & Saito, H. (1985) J. Bacteriol. 161, 552-555] suppress the requirement for spo0B, spo0E, and spo0F gene products in transcription from sigma 28-dependent promoters, suggest that the Spo0A protein interacts directly with the transcription machinery to effect the initiation of sporulation. The deduced amino acid sequence of the Spo0A protein was highly related to that of the OmpR regulatory protein of Escherichia coli.

[Evaluation of the comparative relationship between HbA1 and HbA1c in subjects with OGTT type diabetes and in normal subjects]

The authors investigated if significantly high glycosylated hemoglobin and glycosylated hemoglobin c levels are present in patients with impaired glucose tolerance tested with oral glucose tolerance test. The patients with impaired glucose tolerance presented higher, but non significantly, glycosylated hemoglobin levels then normal subjects.