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Biomedical subjects

F Franceschi

Publications and source records attributed to F Franceschi.

At least 55 records · Page 3Linked to original sources
PubMed1999

Structural and functional studies on the overproduced L11 protein from Thermus thermophilus.

The L11 ribosomal protein from Thermus thermophilus (TthL11) has been overproduced and purified to homogeneity using a two-step purification protocol. The overproduced protein carries a similar methylation pattern at Lys-3 as does its homolog from Escherichia coli. Chymotrypsin digested only a small part of the TthL11 protein and did not cleave TthL11 into two peptides, as in the case of EcoL11, but produced only a single N-terminal peptide. Tryptic digestion of TthL11 also produced an N-terminal peptide, in contrast to the C-terminal peptide obtained with L11 from Bacillus stearothermophilus. The recombinant protein forms a specific complex with a 55-nt 23S rRNA fragment known to interact with members of the L11 family from several organisms. Cooperative binding of TthL11 and thiostrepton to 23S rRNA leads to an increased protection of TthL11 from tryptic digestion. The similar structural and biochemical properties as well as the significant homology between L11 from E. coli and B. stearothermophilus with the corresponding protein from Thermus thermophilus indicate an evolutionarily conserved protein important for ribosome function.

Amino Acid Sequence↗
PubMed1999

Ribosomal gene disruption in the extreme thermophile Thermus thermophilus HB8. Generation of a mutant lacking ribosomal protein S17.

S17 is a primary rRNA-binding protein which has been implicated in ribosome assembly and translational fidelity. We describe the generation and biochemical characterization of an S17 minus ribosomal mutant, a ribosomal protein-lacking mutant obtained in Thermus thermophilus HB8. The S17 mutant was obtained by insertional inactivation of the target gene with the kanamycin adenyl transferase (kat) gene, making use of a Thermus-Escherichia shuttle vector and the natural ability of Thermus to transform. In the final construct used to transform Thermus cells, the S17 coding region was replaced with the kat gene cloned in-frame with the first three amino acids of S17. Hence, in vivo transcription of the kat gene was under the control of the ribosomal operon promoter. As in Escherichia coli, the Thermus S17 mutant exhibited a temperature-sensitive phenotype. Two-dimensional PAGE, Western blot, and ELISA confirmed the absence of S17 from the mutant ribosomes. Sucrose-gradient profiles of mutant cells showed a clear separation and normal proportions of 50S and 30S subunits and a normal ratio between them. In addition, the S17 mutant showed the presence of a 20S peak representing assembly-defective particles. The successful re-incorporation of protein S17 into the mutant ribosomes was demonstrated when reconstitution with isolated S17 was performed at 60 degrees C.

Anti-Bacterial Agents↗
PubMed1999

Insulin-dependent diabetes mellitus affects eradication rate of Helicobacter pylori infection.

BACKGROUND: Patients with insulin-dependent diabetes mellitus (IDDM) are often affected by chronic infections; however, antibiotic absorption may be influenced by the disease. Helicobacter pylori, the most common gastric infection worldwide, is the main acquired factor in the pathogenesis of gastritis and peptic ulcer. The aim of the study was to compare the H. pylori eradication rate obtained with a standard 7-day antibiotic regimen in a group of IDDM H. pylori infected patients and in a control group of infected dyspeptic patients. METHODS: Thirty-one patients (18 male, 13 female, 39+/-12 years) affected by IDDM and H. pylori infection, and 50 dyspeptic infected patients (23 male, 17 female, 37+/-10 years) were evaluated. H. pylori infection was assessed through 13C-urea breath test. A triple therapy with amoxycillin (1 g b.i.d.), clarithromycin (250 mg t.i.d.) and pantoprazole (40 mg b.i.d.) was given to both groups at the time of diagnosis for 7 days. Cure was defined as the absence of H. pylori infection, assessed by 13C-urea breath test, 6 weeks after completing anti-microbial therapy. Effects of H. pylori eradication on gastrointestinal symptoms (pyrosis, epigastric pain, belching, bloating, halitosis and nausea) were also evaluated. RESULTS: All enrolled patients completed the study. When compared to dyspeptic patients, the eradication rate was significantly lower in IDDM patients: 92% (46/50) versus 65% (20/31), respectively (P < 0.002). IDDM patients infected by H. pylori showed a different prevalence of some of the gastrointestinal symptoms assessed when compared to the infected dyspeptic patients; in particular, pyrosis, epigastric pain and belching were significantly more prevalent in the infected dyspeptic group. After H. pylori eradication, both groups showed a significant reduction of the intensity of all the gastrointestinal symptoms evaluated, except for nausea. CONCLUSIONS: IDDM patients showed a significantly lower H. pylori eradication rate when compared to that observed in dyspeptic subjects. The dosage and/or the duration of a standard eradication regimen does not appear to be sufficient to eradicate the infection in IDDM patients. The impairment of the gastrointestinal mucosa microvasculature with a reduction of antibiotic absorption, or the frequent use of antibiotics for other infections with development of resistant strains, may be the mechanisms underlying the observation.

Adult↗
PubMed1999

Clinical and neurophysiological abnormalities before and after reconstruction of the anterior cruciate ligament of the knee.

OBJECTIVES: We aimed to study knee proprioception and somatosensory evoked potentials (SEPs) to stimulation of the common peroneal nerve (CPN) in 7 patients with lesion of the anterior cruciate ligament (ACL) before and after ACL reconstruction. MATERIALS AND METHODS: We recorded the spinal N14 and scalp P27 potentials in 5 patients, while in the remaining 2 patients we calculated scalp SEP maps by 20 electrodes. The knee proprioception was tested by comparing the sensitivity to movement of both the knees. RESULTS: Before surgery, all patients showed decreased knee position sense and lack of the cortical P27 potential on the side of the ACL lesion. Arthroscopic reconstruction of the ligament improved neither the knee proprioception nor the somatosensory central conduction. CONCLUSION: We suggest that the loss of the knee mechanoreceptors can be followed by modifications of the central nervous system, which are not compensated by other nervous structures.

Anterior Cruciate Ligament↗
PubMed1999

Extradigestive manifestations of Helicobacter pylori gastric infection.

In the past year, several studies have been carried out on the association between Helicobacter pylori infection and a miscellany of extradigestive diseases, such as cardiovascular, immunological, and various other pathologies. In particular, a higher prevalence of H pylori infection in patients affected by ischaemic heart disease has been described and there is growing evidence for an association between H pylori and some autoimmune diseases. Moreover, recent studies have shown that various helicobacter species have been detected in human bile; if confirmed, this finding could revise the diagnostic and therapeutic approach to diseases of the biliary tract.

Autoimmune Diseases↗
PubMed1999

Aspirin inhibits androgen response to chorionic gonadotropin in humans.

Eicosanoids play an important role in the regulation of the hypothalamic-pituitary axis; less clear is their role in testicular steroidogenesis. To evaluate the involvement of cyclooxygenase metabolites, such as prostaglandins, in the regulation of human testicular steroidogenesis, we examined the effects of a prostaglandin-blocker, aspirin, on plasma testosterone, pregnenolone, progesterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol response to human chorionic gonadotropin (hCG) in normal male volunteers in a placebo-controlled, single-blinded study. To test the efficacy of aspirin, seminal prostaglandin E(2) levels were also determined. hCG stimulation increased peripheral levels of testosterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol, without affecting circulating pregnenolone and progesterone values. Aspirin significantly lowered seminal prostaglandin E(2) levels, whereas it did not modify steroid concentrations not exposed to exogenous hCG. Moreover, the drug significantly reduced the response of testosterone, 17OH-progesterone, androstenedione, and dehydroepiandrosterone to hCG, as assessed by the mean integrated area under the curve, whereas it did not influence 17beta-estradiol response. In conclusion, aspirin treatment inhibits androgen response to chorionic gonadotropin stimulation in normal humans. The action of aspirin is probably mediated via an effective arachidonate cyclooxygenase block.

Administration, Oral↗
PubMed1999

Prevalence and causal conditions for amputation surgery in the third world: ten years experience at Dodoma Regional Hospital, Tanzania.

This is a partly retrospective study of 252 major limb amputations carried out in regional hospital in Tanzania over a period of ten years mostly by the authors. The paper reports on the aetiology and levels of amputation and identifies prevalence and sex of the amputees. The causes of amputation classified under tumours, vascular diseases, trauma, infections, burns, animal bites, iatrogenic causes, maduromycosis and miscellanea--are discussed with particular reference to the influence of the environment, cultural habits and local customs.

Adolescent↗
PubMed1998

Crystallographic studies on the ribosome, a large macromolecular assembly exhibiting severe nonisomorphism, extreme beam sensitivity and no internal symmetry.

Crystals, diffracting best to around 3 A, have been grown from intact large and small ribosomal subunits. The bright synchrotron radiation necessary for the collection of the higher-resolution X-ray diffraction data introduces significant decay even at cryo temperatures. Nevertheless, owing to the reasonable isomorphism of the recently improved crystals of the small ribosomal subunits, reliable phases have been extracted at medium resolution (5-6 A) and an interpretable five-derivative MIR map has been constructed. For the crystals of the large subunits, however, the situation is more complicated because at higher resolution (2.7-7 A) they suffer from substantial radiation sensitivity, a low level of isomorphism, instability of the longest unit-cell axis and nonisotropic mosaicity. The 8 A MIR map, constructed to gain insight into this unusual system, may provide feasible reasoning for the odd combination of the properties of these crystals as well as hints for future improvement. Parallel efforts, in which electron-microscopy-reconstructed images are being exploited for molecular-replacement studies, are also discussed.

Animals↗
PubMed1998

Studies on the Zn-containing S14 ribosomal protein from Thermus thermophilus.

The S14 ribosomal protein from the thermophilic organism Thermus thermophilus, which contains a zinc-finger-like motif, namely -C-X2-C-X12-C-X2-C- [Tsiboli, P. & Choli, T. (1995) Biol. Chem. Hoppe-Seyler 376, 127-130], has been overproduced, purified and investigated for its zinc content. According to atomic absorption experiments, the protein contains zinc at a molar ratio of one. Denaturation experiments with simultaneous use of denaturing and chelating agents (guanidine hydrochloride and EDTA), as well as renaturation experiments, have shown both that Zn is strongly bound to the protein and with 1:1 Zn/protein stoicheiometry. These findings provide very strong evidence in support of the participation of the zinc-finger motif and the Zn in the formation of a zinc-finger domain.

Amino Acid Sequence↗
PubMed1998

Functional universality and evolutionary diversity: insights from the structure of the ribosome.

The structure of the mammalian ribosome, reconstructed at 25 A resolution, has added a new dimension to our current knowledge, as it manifests the conservation and universality of the ribosome in respect to its primary tasks in protein biosynthesis. A combined approach to study of the ribosome, using X-ray crystallography and electron microscopy, may further improve our understanding of ribosome function in the future.

Animals↗
PubMed1998

Raynaud's Phenomenon and Helicobacter Pylori Infection.

Raynaud's phenomenon is an intermittent vasospasm of the arterioles of the distal limbs which occurs mostly following exposure to cold or emotional stimuli. Helicobacter pylori infection, the most relevant cause of gastritis, has been associated with some vascular diseases. The aim of this study was to assess the prevalence of H. pylori infection and effects of eradication on Raynaud attacks. Twenty-five patients affected by primary Raynaud's phenomenon were evaluated. H. pylori infection was assessed by the 13C urea breath test and 20 subjects were found to be infected by the bacterium. Triple therapy consisting of amoxicillin, clarithromycin, and lansoprazole was given to the patients for 7 days at the time of diagnosis. Duration and frequency of clinical attacks of Raynaud's phenomenon per week were assessed for 12 weeks after eradication. In 80 percent of the patients Raynaud's was eradicated after therapy. Clinical attacks of Raynaud's phenomenon completely disappeared in 18% of the eradicated patients. Duration and frequency of attacks were significantly reduced in 68% of the remaining patients. The preliminary findings from this study show that H. pylori eradication significantly ameliorates primary Raynaud's disease.

Journal Article↗
PubMed1998

Primary Headache and Helicobacter Pylori.

H. pylori infection has recently been associated with various vascular disorders. The aim of this study was to investigate its role in primary headache, a pathology strictly associated with vascular alterations. A total of 200 subjects affected by primary headache were evaluated. H. pylori infection was diagnosed by the 13C urea breath test. Headache was classified in tension-type headache, cluster headache, and migraine with or without aura. Prevalence of H. pylori infection and gastrointestinal (GI) symptoms were evaluated. H. pylori infection was found in 40% of the patients; prevalence of migraine without aura was found to be significantly greater in infected patients. The positive group showed no significant differences in the prevalence of the GI symptoms evaluated. In 30 infected patients, it was assessed whether the eradication of the bacterium was able to reduce frequency, intensity, and duration of clinical attacks of headache. After eradication, clinical attacks of headache completely disappeared in 17% of patients. Moreover, intensity, duration, and frequency of headache attacks were reduced in 69% of the remaining subjects. In conclusion, H. pylori infection is common in primary headache; bacterium eradication appears to be related to a significant reduction in clinical attacks of the disease.

Journal Article↗
PubMed1998

Helicobacter pylori eradication ameliorates primary Raynaud's phenomenon.

Raynaud's phenomenon is defined by an intermittent vasospasm of the arterioles of the distal limbs. Helicobacter pylori infection has been recently associated with Raynaud's phenomenon. The aim of this study was to assess the effects of H. pylori eradication on Raynaud's attacks. Forty-six patients affected by primary Raynaud's phenomenon were evaluated. H. pylori infection was assessed by [13C]urea breath test. Eradication therapy was given to infected patients for seven days. Discomfort and the duration and frequency of attacks of Raynaud's phenomenon per week were assessed. Thirty-six subjects were infected with H. pylori; the bacterium was eradicated in 83% of these after therapy. Attacks of Raynaud's phenomenon completely disappeared in 17% of the patients with H. pylori eradication. Discomfort and the duration and frequency of attacks of Raynaud's phenomenon were significantly reduced in 72% of the remaining patients. Conversely, attacks of Raynaud's disease did not change significantly during the 12-week follow-up period either in the H. pylori-negative patients or in the infected subjects in whom the bacterium was not eradicated by therapy. The study shows that H. pylori eradication causes a significant decrease in clinical attacks of Raynaud's disease. The reduction of vasoactive substances determined by the eradication of the bacterium may be the pathogenetic mechanism underlying the phenomenon.

Adult↗
PubMed1998

Beneficial effects of Helicobacter pylori eradication on idiopathic chronic urticaria.

Helicobacter pylori, the most important cause of gastritis and peptic ulcer, recently has been associated with several extradigestive diseases. The aim of this study was to assess the prevalence of Helicobacter pylori infection and the effects of bacterium eradication in 42 consecutive patients affected by idiopathic chronic urticaria. Helicobacter pylori was assessed by [13C]urea breath test. Amoxicillin, clarithromycin, and lansoprazole were given to infected patients for seven days. Urticaria and gastrointestinal symptoms were assessed on enrollment and after eradication. Fifty-five percent of patients proved to be infected by Helicobacter pylori. Prevalence of gastrointestinal symptoms did not differ between infected and uninfected patients. Eighty-eight percent of infected patients in whom the bacterium was eradicated after therapy showed a total or partial remission of urticaria symptoms. Conversely, symptoms remained unchanged in all uninfected patients. In conclusion, Helicobacter pylori affects a high percentage of patients with idiopathic chronic urticaria; however, typical gastrointestinal symptoms do not identify infection status. Bacterium eradication is associated with a remission of urticaria symptoms, suggesting a possible role of Helicobacter pylori in the pathogenesis of this skin disorder.

Aged↗
PubMed1998

Helicobacter pylori infection in patients affected by insulin-dependent diabetes mellitus.

BACKGROUND/AIM: Insulin-dependent diabetes mellitus (IDDM) is the result of an autoimmune destruction of pancreatic Langerhans beta cells. Helicobacter pylori infection, the most common cause of gastritis and peptic ulcer, has been associated with some autoimmune diseases. The aim of this study was to evaluate the prevalence of H. pylori infection and gastrointestinal (GI) symptoms in patients with IDDM. METHODS: 116 patients (50 males and 66 females, mean age: 35 +/- 11 years) affected by IDDM were evaluated; 50 healthy subjects matched for age and sex were utilized as a control group. H. pylori infection was determined by a [13C]urea breath test. IDDM duration, daily dosage of insulin and prevalence of GI symptoms (bloating, pyrosis, epigastric pain, belching, halitosis, nausea) were assessed. RESULTS: The prevalence of H. pylori infection was similar in IDDM patients and in controls (37 vs 34%, respectively). In both groups, the mean age was higher in infected subjects. The mean IDDM duration was significantly greater in infected patients (19 +/- 12 vs 13 +/- 10 years, P < 0.006). Prevalence of infection was directly related to the duration of IDDM (<1 year, 23%; 1-3 years, 32%; >3 years, 40%). The daily dosage of insulin did not differ between infected and non-infected subjects. H. pylori contaminated patients showed a significantly higher prevalence of bloating, pyrosis and epigastric pain when compared with non-infected subjects; conversely, prevalence of belching, halitosis and nausea did not differ between groups. CONCLUSION: The prevalence of H. pylori infection is high in patients affected by IDDM; however, it does not differ from the infection rate observed in a control group. The rate of infection increases with IDDM duration. Bloating, pyrosis and epigastric pain appear to define infection status better.

Adult↗