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P Alberti

Publications and source records attributed to P Alberti.

At least 19 recordsLinked to original sources
PubMed2000

Backbone dynamics of Tet repressor alpha8intersectionalpha9 loop.

A set of single Trp mutants of class B Tet repressor (TetR), in which Trp residues are located from positions 159 to 167, has been engineered to investigate the dynamics of the loop joining the alpha-helices 8 and 9. The fluorescence anisotropy decay of most mutants can be described by the sum of three exponential components. The longest rotational correlation time, 30 ns at 10 degrees C, corresponds to the overall rotation of the protein. The shortest two components, on the subnanosecond and nanosecond time scale, are related to internal motions of the protein. The initial anisotropy, in the 0.16-0.22 range, indicates the existence of an additional ultrafast motion on the picosecond time scale. Examination of physical models for underlying motions indicates that librational motions of the Trp side chain within the rotameric chi(1) x chi(2) potential wells contribute to the picosecond depolarization process, whereas the subnanosecond and nanosecond depolarization processes are related to backbone dynamics. In the absence of inducer, the order parameters of these motions, about 0.90 and 0.80 for most positions, indicate limited flexibility of the loop backbone. Anhydrotetracycline binding to TetR induces an increased mobility of the loop on the nanosecond time scale. This suggests that entropic factors might play a role in the mechanism of allosteric transition.

Bacterial Proteins↗
PubMed2000

Development of a new vaccine formulation that enhances the immunogenicity of tumor-associated antigen CaMBr1.

Aberrant glycosylation is one of the most constant traits of malignant cells. The CaMBr1 hexasaccharide antigen, originally defined on the human breast carcinoma cell line MCF7, is expressed on some normal tissues but overexpressed in a high percentage of human breast, ovary, prostate and lung carcinomas. CaMBr1 overexpression is associated with poor prognosis. The epitope consists of the tetrasaccharide Fuc(alpha1-2)Ga1(beta1-3)GalNAc(beta1-3)Ga1alpha-O-spacer, which has recently become available as a synthetic oligosaccharide. Here we report the CaMBr1 tetrasaccharide conjugation to two different carrier proteins (CRM197 and KLH) and the evaluation of conjugate immunogenicity in mice following their administration in various vaccine formulations with two adjuvants (MPL-SE and Detox-PC). Radioimmunoassay to determine the level and isotype of anti-tetrasaccharide antibodies in mouse sera, and cytofluorimetric analysis and 51Cr-release assay on human tumor cells, to evaluate specificity of binding and complement-dependent lysis respectively, identified CaMBr1-CRM197, in association with the MPL-SE adjuvant, as the best vaccine formulation. This combination induced (1) production of tetrasaccharide-specific antibodies, with negligible side-effects; (2) antibodies with complement-mediated cytotoxic activity on human CaMBr1-positive cells and (3) a high titer of IgG1 detected in sera obtained 3 months after the first injection, indicating that the anti-tetrasaccharide antibody response was mediated by T cell activation. The availability of CaMBr1-glycoconjugate in the minimal and functional antigenic structure and the identification of an efficacious vaccine formulation opens the way to exploring the activity of this glycoconjugate in a clinical setting.

ABO Blood-Group System↗
PubMed2000

Trp scanning analysis of Tet repressor reveals conformational changes associated with operator and anhydrotetracycline binding.

We analysed the conformational states of free, tet operator-bound and anhydrotetracycline-bound Tet repressor employing a Trp-scanning approach. The two wild-type Trp residues in Tet repressor were replaced by Tyr or Phe and single Trp residues were introduced at each of the positions 162-173, representing part of an unstructured loop and the N-terminal six residues of alpha-helix 9. All mutants retained in vivo inducibility, but anhydrotetracycline-binding constants were decreased up to 7.5-fold when Trp was in positions 169, 170 and 173. Helical positions (168-173) differed from those in the loop (162-167) in terms of their fluorescence emission maxima, quenching rate constants with acrylamide and anisotropies in the free and tet operator-complexed proteins. Trp fluorescence emission decreased drastically upon atc binding, mainly due to energy transfer. For all proteins, either free, tet operator bound or anhydrtetracycline-bound, mean fluorescence lifetimes were determined to derive quenching rate constants. Solvent-accessible surfaces of the respective Trp side chains were calculated and compared with the quenching rate constants in the anhydrotetracycline-bound complexes. The results support a model, in which residues in the loop become more exposed, whereas residues in alpha-helix 9 become more buried upon the induction of TetR by anhydrotetracycline.

Bacterial Proteins↗
PubMed1999

Pancreatic regeneration after subtotal distal resection in rats. Effects of bombesin and octreotide by the in vivo bromodeoxyuridine uptake technique.

Forty male Wistar rats were randomly allocated to four treatment groups after 90% distal pancreatectomy: group A (control) received saline (0.5 ml subcutaneously); group B received bombesin (BBS; 10 microg/kg intraperitoneally); group C received octreotide (2.5 microg/kg subcutaneously), and group D received BBS and octreotide. All substances were injected three times a day until sacrifice after 28 days. BBS increased pancreas weight (p = 0.003) and DNA synthesis (p < 0.001), as measured by a bromodeoxyuridine nuclear-labeling index (BrdU LI). The simultaneous administration of octreotide significantly decreases the remnant pancreas weight (p = 0.016) as compared to group B rats; however the BrdU LI is not significantly reduced in group D as compared to group B. BBS administration promotes regeneration of the remnant pancreas in terms of hypertrophy and hyperplasia. Although octreotide appears to significantly reduce the pancreatic weight increase induced by BBS, it does not reduce DNA synthesis and cell proliferation.

Animals↗
PubMed1997

Structural investigation of Tet repressor loop 154-167: a time-resolved fluorescence study of three single Trp mutants.

We have studied the time-resolved fluorescence of three engineered Tet repressor (TetR) mutants bearing a single Trp residue at positions 162, 163, and 165 in the C-terminal part of the loop joining helices 8 and 9. Detailed analysis indicates that, at 20 degrees, the fluorescence decay of each Trp can be described as the sum of three exponential components with lifetimes in the 1-, 3-, and 6-ns range. Emission wavelength and temperature dependence studies are consistent with a model in which these components are due to the existence of three classes of Trp residues non-interconverting on the nanosecond timescale. Within the framework of the rotamer model, the weak temperature dependence of the lifetimes strongly suggests that the secondary structure of the loop, at least in the 162-165 range, is not altered with temperature. The equilibrium between the rotamers is characterized by an enthalpy-entropy compensation effect which strongly suggests the involvement of background structural regions of TetR in the thermodynamics of the process. The very high deltaH degrees and TdeltaS degrees observed (up to 18 kcal/ mol) should reflect the temperature-dependent conformational change of a large part of the protein which would alter the rotamer distribution of the Trp residues. Taken together, our results are consistent with the existence of (at least) two conformations of the loop and suggest a model for loop motion.

Bacterial Proteins↗
PubMed1996

Effect of octreotide on pancreatic regeneration in rats measured by bromodeoxyuridine uptake.

OBJECTIVE: To study the effects of up to 60 days intermittent octreotide on regeneration of rat pancreas stimulated by cholecystokinin after 70% distal resection. DESIGN. Random controlled experimental study. SETTING: University hospital, Italy. MATERIALS: 60 Male Wistar rats. INTERVENTIONS: Distal resection of splenic and gastric lobes of pancreas (70% of whole gland). Rats were allocated to three groups (n = 20 in each): group A (control) were given saline solution 0.5 ml; group B were given cholecystokinin 300 ng/kg; and group C were given cholecystokinin 300 ng/kg and octreotide 2.5 micrograms/kg. All substances were injected subcutaneously twice a day until death. Four rats were killed weekly for four weeks, and the remainder at 60 days. MAIN OUTCOME MEASURES: Increase in weight of the gland as a percentage of the weight of the whole gland, and DNA synthesis measured by bromodeoxyuridine (BrdU) nuclear labelling index. RESULTS: In the cholecystokinin alone group pancreatic weight had increased significantly on days 21 and 28 (95% confidence intervals (CI) - 13.8 to 12.2 and -44.1 to 19.7, respectively) and the BrdU index had increased significantly at 21 (0.56 to 0.80), 28 (0.26 to 1.3), and 60 (0.09 to 0.51) days compared with the control group. In the group given both cholecystokinin and octreotide the weight was significantly lower than in the cholecystokinin alone group at 21 and 28 days (95% CI - 1.02 to 66.7 and 3.5 to 34.7, respectively) and the BrdU index was significantly lower at 28 days (0.40 to 1.19). CONCLUSIONS: Octreotide seems to reduce the pancreatic regeneration induced by cholecystokinin in rats after 70% distal resection. To our knowledge this has not previously been shown, and the mechanism must be elucidated further.

Animals↗
PubMed1996

[Gangrenous cystitis. Case report].

A rare case of gangrenous cystitis is described. The questions of the incidence of this pathology are discussed, considering its rareness after the antibiotics age. The etiology of this disease is probably multifactorial and it is never possible to identify a unique cause. The gangrenous cystitis doesn't present with any typical symptomatology, out with urinary troubles common to many urologic diseases. Surgery is often performed in emergency without a preoperative defined diagnosis. Surgical treatment has changed with time from a simple bladder cavity draining to the resection of the necrotized bladder wall. In our case a total cystectomy with uretero-ileocutaneostomy, in two times, was performed. This procedure allowed the patient a good quality of life (1 year of follow-up).

Cystitis↗
PubMed1996

[Unusual cause of gastric bleeding: leiomyoma].

The gastric leiomyoma is a rare non-epithelial tumor of the stomach that can either be asymptomatic (autoptical diagnosis) or, on the contrary, suddenly appear with severe gastric hemorrhage. The authors review the literature and report their own experience concerning 6 cases of gastric leiomyoma observed during 5 years. They discuss the clinical presentation, the difficulties of diagnosis and the therapeutic choices.

Aged↗
PubMed1994

[Splenic abscess: case report and review of the literature].

After the observation of a case of splenic abscess the authors make a review of the literature. It is important to note that splenic abscesses are increasing in number because of some particular situations that can help their development. The diagnosis is not always easy and quick, because of the frequent lack of a typical symptomatology, and the later the diagnosis, the worse the prognosis. Besides, classical surgical therapy must be considered for selected cases, a conservative therapy that can be very useful for patients in very poor conditions.

Abscess↗
PubMed1993

Ribosomal protein S6 kinase and protein kinase C activation by epidermal growth factor after temporary renal ischemia.

An initial event in cell response to growth factors is the change in the state of phosphorylation of a number of cellular proteins playing a role in cell proliferation. The effects of a single dose of exogenously administered epidermal growth factor (EGF) on renal serine/threonine protein kinases such as ribosomal protein S6 kinase(s) and protein kinase C (PKC) and on [3H]thymidine incorporation into tubule cell nuclei have been studied during the regenerative repair response after temporary renal ischemia in the rat, followed by reperfusion for up to 72 h. During the postischemic reflow, the PKC and S6 kinase activities increased at 24 and 72 h, respectively. EGF anticipated both increases: the PKC at 4 and the S6 kinase(s) at 24 h. Associated with this EGF-induced rise of S6 kinase activity, a significant increase in renal tubule cell proliferation was observed. These studies suggest the presence of a growth factor-activated serine/threonine phosphorylation cascade in the rat kidney participating in the regulation of cell growth during recovery from an ischemic insult.

Animals↗
PubMed1993

Human papilloma virus infection and Ki-ras oncogene in paraffin-embedded squamous carcinomas of the cervix.

42 paraffin-embedded squamous cervical carcinomas were screened for the presence of human papilloma virus (HPV; 6b, 11, 16, 18) and for activation of the Ki-ras oncogene family by polymerase chain reaction. In 72% of cases we found one or more HPV types, but no mutations of the Ki-ras gene (codon 12-1 and 61-1, 61-2 and 61-3) were found. We conclude that mutations of the Ki-ras oncogene, at the positions analyzed, are not likely to be involved in the events leading to cervical carcinogenesis.

Carcinoma, Squamous Cell↗
PubMed1993

[Primary stones of the common bile duct].

Primary stones can probably form, although rarely, in the common bile duct. The authors report a series of six cases which they considered as primary common duct stone disease and, in order to get more precise information on this problem, they review the literature on the subject. This disease would be caused by the presence of a lithogenic bile which, with a chronic obstruction of the Vater's ampulla, could let lithiasic particles accumulate in the common bile duct. On the basis of this hypothesis and in order to perform a correct procedure that allows easy drainage of the bile to the intestine to the chronic use of litholytic drugs.

Adult↗
PubMed1992

Ribosomal protein S6 kinase is activated after folic acid injury and epidermal growth factor administration but not after unilateral nephrectomy in the rat kidney.

Following loss of functional renal mass induced by a single parenteral injection of folic acid, the increased proliferation of tubular epithelium to replace injured and necrotic cells was associated with S6 kinase activation and enhanced phosphorylation of this ribosomal protein in vitro, EGF administered 1.5 h after folic acid promoted the phosphorylation of S6 protein and accelerated the regenerative repair process. In contrast, the hypertrophic response of the kidney following uninephrectomy was not associated with S6 kinase activation. The results of this study suggest a close correlation between levels of S6 protein phosphorylation and the degree of cell proliferation in the rat kidney.

Animals↗
PubMed1992

[Mondor syndrome. Etiopathogenesis and case report].

The Authors observed and report a case of Mondor's syndrome in a male. In the attempt to identify the real origin in this peculiar thrombophlebitis they reviewed the recent literature. It is apparently impossible to drawn definitive conclusions from the different studies on this subject. Anyway Mondor's syndrome looks suitable for inclusion in the group of jumping thrombophlebitis. Therefore the real cause of the venous accident should be a pathologic situation next to the venous branch where the thrombophlebitis has broken out.

Adult↗
PubMed1992

[Tumors of the small intestine. Case reports and comments].

Tumours of the small intestine are extremely rare and have a particularly severe prognosis. The impossibility of making an early diagnosis due to the scarcity of precise symptoms during the early stages of the disease and the lack of safe instrumental tests limits the results of treatment which is essentially surgical. In order to contribute to the study of the disease and improve its prognosis, the authors report the cases which they have observed and review the literature.

Adult↗
PubMed1990

Picotamide protects mice from death in a pulmonary embolism model by a mechanism independent from thromboxane suppression.

We have previously characterized the new antiplatelet agent picotamide as a dual thromboxane synthase inhibitor/thromboxane A2 receptor antagonist in human platelets. We have now studied the antithrombotic activity of this drug in a simple animal model of lung platelet thromboembolism in the mouse. Picotamide, given i.p. 1 hr before the thrombotic challenge, protected mice from death caused by the i.v. injection of collagen plus epinephrine in a dose-dependent way; the dose reducing mortality by 50% was 277 mg/kg while for aspirin it was 300 mg/kg. Picotamide was also able to reduce the mortality provoked by the i.v. injection of the stable TxA2 mimetic U46619; BM 13.505, a pure TxA2-receptor blocker, was also effective while aspirin was totally inactive. Picotamide, finally, reduced the lethal consequences of the i.v. injection of a 12.5% suspension of hardened rat red blood cells, a model in which platelets are not involved; aspirin was totally ineffective in this model while nicardipine, a calcium channel blocker, was active. Picotamide did not inhibit the formation of TxB2 in serum at any of the doses tested (100 to 750 mg/kg i.p.) while it did enhance significantly PGI2-synthesis from mice aortae and, even more, from mice lungs. The i.v. administration of picotamide (250 mg/kg 2 min before the thrombotic challenge) lead to a strong inhibition of serum TxB2 (-84.6%) and was associated with a higher antithrombotic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗