Basaloid squamous cell carcinoma of the larynx: report of a early laryngeal cancer.

Basaloid squamous cell carcinoma is a recently recognized, rare and aggressive variant of squamous cell carcinoma with a predilection to occur in base of the tongue, hypopharynx and larynx (especially the supraglottic tract). It is usually diagnosed in advanced stage, frequently with distant metastases, requiring aggressive surgical intervention. The prognosis is remarkably poor even after the association of radiotherapy or chemotherapy. Nevertheless recently it has been reported that in the early stage this neoplasm seems to have a behaviour less aggressive, similar to conventional squamous carcinoma. The therapeutic approach is not clearly defined when the neoplasm is diagnosed at an early stage. We present a case of early stage of basaloid squamous cell carcinoma of the supraglottic larynx.

Morphological and functional changes of cardiovascular system in postmenopausal women.

BACKGROUND: The incidence of cardiovascular events in reproductive age women is 3 times lower than in men, whereas this ratio noticeably changes on menopausal beginning. Postmenopausal women are more exposed to the effects of risk factors, which are present in a noticeably different entity in physiological or surgical menopause; and in the latter whether on substitutive hormonal treatment or not. METHODS: This study, carried out in Rome and Latina, has involved 743 postmenopausal women, of whom 545 with physiological menopause and 198 with iatrogenic menopause. RESULTS: The average blood pressure value as well as the incidence of hypertension, hypercholesterolemia, diabetes mellitus, obesity and smoking have a significantly different trend in physiological versus iatrogenic postmenopausal women; and in the latter whether on substitutive hormonal treatment or not. CONCLUSIONS: Studying life-style and evaluating risk factors in postmenopausal women, and giving an up-to-date view about the prevalence oh health conditions at risk, will allow us to promote both primary and secondary prevention actions.

Clinical non-instrumental evaluation of dysphagia.

Clinical non-instrumental evaluation plays an important role in the assessment of the dysphagic patient. This evaluation, called "bedside examination", aims to establish whether dysphagia is present, evaluating severity, determining the alterations which cause it, planning rehabilitation, testing outcome of treatment. The assessment takes into consideration anamnesis regarding the swallowing problem, evaluation of the anatomy and functionality, of sensitivity and the reflexes, of the swallowing apparatus. Finally, the oral feeding test is performed, which evaluates the oral and pharyngeal phases of swallowing. The examination performed in the neurologic patient is different from that performed in the patient submitted to ENT or maxillo-facial surgery.

Activation of class III ribonucleotide reductase from E. coli. The electron transfer from the iron-sulfur center to S-adenosylmethionine.

The anaerobic ribonucleotide reductase (ARR) from E. coli is the prototype for enzymes that use the combination of S-adenosylmethionine (AdoMet) and an iron-sulfur center for generating catalytically essential free radicals. ARR is a homodimeric alpha2 protein which acquires a glycyl radical during anaerobic incubation with a [4Fe-4S]-containing activating enzyme (beta) and AdoMet under reducing conditions. Here we show that the EPR-active S = 1/2 reduced [4Fe-4S]+ cluster is competent for AdoMet reductive cleavage, yielding 1 equiv of methionine and almost 1 equiv of glycyl radical. These data support the proposal that the glycyl radical results from a one-electron oxidation of the reduced cluster by AdoMet. Reduced protein beta alone is also able to reduce AdoMet but only in the presence of DTT. However, in that case, 2 equiv of methionine per reduced cluster was formed. This unusual stoichiometry and combined EPR and Mössbauer spectroscopic analysis are used to tentatively propose that AdoMet reductive cleavage proceeds by an alternative mechanism involving catalytically active [3Fe-4S] intermediate clusters.

Activation of class III ribonucleotide reductase by flavodoxin: a protein radical-driven electron transfer to the iron-sulfur center.

In its active form, Escherichia coli class III ribonucleotide reductase homodimer alpha(2) relies on a protein free radical located on the Gly(681) residue of the alpha polypeptide. The formation of the glycyl radical, namely, the activation of the enzyme, involves the concerted action of four components: S-adenosylmethionine (AdoMet), dithiothreitol (DTT), an Fe-S protein called beta or "activase", and a reducing system consisting of NADPH, NADPH:flavodoxin oxidoreductase, and flavodoxin (fldx). It has been proposed that a reductant serves to generate a reduced [4Fe-4S](+) cluster absolutely required for the reductive cleavage of AdoMet and the generation of the radical. Here, we suggest that the one-electron reduced form of flavodoxin (SQ), the only detectable product of the in vitro enzymatic reduction of flavodoxin, can support the formation of the glycyl radical. However, the redox potential of the Fe-S center of the enzyme is shown to be approximately 300 mV more negative than that of the SQ/fldx couple and not shifted to a more positive value by AdoMet binding. It is also more negative than that of the HQ/SQ couple, HQ being the fully reduced form of flavodoxin. Our interpretation is that activation of ribonucleotide reductase occurs through coupling of the reduction of the Fe-S center by flavodoxin to two thermodynamically favorable reactions, the oxidation of the cluster by AdoMet, yielding methionine and the 5'-deoxyadenosyl radical, and the oxidation of the glycine residue to the corresponding glycyl radical by the 5'-deoxyadenosyl radical. The second reaction plays the major role on the basis that a Gly-to-Ala mutation results in a greatly decreased production of methionine.

Activation of class III ribonucleotide reductase by thioredoxin.

Anaerobic ribonucleotide reductase provides facultative and obligate anaerobic microorganisms with the deoxyribonucleoside triphosphates used for DNA chain elongation and repair. In Escherichia coli, the dimeric alpha2 enzyme contains, in its active form, a glycyl radical essential for the reduction of the substrate. The introduction of the glycyl radical results from the reductive cleavage of S-adenosylmethionine catalyzed by the reduced (4Fe-4S) center of a small activating protein called beta. This activation reaction has long been known to have an absolute requirement for dithiothreitol. Here, we report that thioredoxin, along with NADPH and NADPH:thioredoxin oxidoreductase, efficiently replaces dithiothreitol and reduces an unsuspected critical disulfide bond probably located on the C terminus of the alpha protein. Activation of reduced alpha protein does not require dithiothreitol or thioredoxin anymore, and activation rates are much faster than previously reported. Thus, in E. coli, thioredoxin has very different roles for class I ribonucleotide reductase where it is required for the substrate turnover and class III ribonucleotide reductase where it acts only for the activation of the enzyme.