Biomedical subjects
Publications and source records attributed to F Poletti.
We report compression of low-power femtosecond pulses at 1.06 microm in a dispersion-decreasing holey fiber. Near-adiabatic compression of 130 fs pulses down to 60 fs has been observed. Measured spectra and pulse shapes agree well with numerical simulations. Compression factors of ten are possible in optimized fibers.
We report the results of detailed measurements on the Brillouin frequency shift (BFS), gain bandwidth, and gain coefficients of several small-core holey optical fibers (HFs) of both uniform and axially varying structural characteristics and compare these with measurements on more conventional fibers. Our measurements show that the BFS of HFs is first-order proportional to the modal index for light propagating along the fiber and is thus extremely sensitive to its precise structural parameters. Our results highlight the possibility of using distributed Brillouin scattering measurements to perform nondestructive structural characterization of HFs, and the possibility of producing Brillouin-suppressed HFs using controlled structural variation along the fiber length.
Patients with AIDS present a wide variety of clinical manifestations through involvement of various organs. Ultrasonography (US) is easy to perform, safe, inexpensive, not invasive and repeatable. Those features are crucial for AIDS patients, who in industrialised countries are now mostly seen on an outpatient basis thanks to the introduction of Highly Active Antiretroviral Therapy. US can investigate most of the organs affected in AIDS and can guide biopsies, allowing the cyto-histological and microbiological investigations needed for a definitive diagnosis. This paper reviews the wide variety of applications of abdominal US and stresses its importance in the management of a complex and changing condition, particularly in settings where other more expensive imaging techniques are not--and will not be for a long time--available. The increasing use of portable/hand-carried scanners further adds to the value of the technique in such settings. With new treatments, prevalence and morbidity/mortality rates change, but new conditions and new side effects appear. US applications to these new conditions are discussed as well.
Bacillus cereus has sometimes been implicated in food poisoning and in opportunistic infections of seriously ill patients. This report describes an unusual case of persistent bacteremia and multiple organ failure associated with B. cereus in a patient admitted to our institution for lung cancer. The patient was undergoing treatment with an antimicrobial agent (imipenem) that was shown to be effective against the micro-organism in vitro. No portal of entry for the strain was detected. After treatment with vancomycin, also shown to be effective in vitro, no clinical improvement was noted and the patient died. Molecular studies showed that the same strain caused an episode of pseudobacteremia in another patient admitted to the same ICU room.
The introduction of HAART has changed the nutritional status of HIV patients. In the pre-protease inhibitor (PI) era, more than 60% of HIV-positive persons presented with protein energy malnutrition (PEM) and vitamin and mineral deficit. This caused progressive physical-metabolic wasting (wasting syndrome/cachexia) and increased susceptibility to opportunistic infections and drug toxicity. PEM was a concurrent cause in 80% of deaths attributed to AIDS. Since 1996, the year in which PIs were introduced, the number of patients dying as a result of AIDS has decreased by two thirds, and cachexia is no longer the AIDS terminal phase in developed countries. But different patterns of nutritional status changes have appeared in association with the use of newer anti-HIV therapies and with longer survival of HIV-infected patients. A new clinical and laboratory syndrome--lipodystrophy syndrome--now affects patients receiving PI-based therapy. This syndrome consists of changes in body shape that are caused by an abnormal redistribution of fat. Fat accumulates in the abdominal area (truncal and visceral obesity), in the axillary pads (bilateral symmetric lipomatosis), and in the dorsocervical pads ("buffalo hump," "bull neck") but decreases in the legs, arms, and nasolabial and cheek pads (peripheral lipodystrophy). Hyperlipidemia and insulin resistance are also frequently present (metabolic syndrome X). Pathogenic mechanisms of lipid and fat tissue disturbances are discussed in this article, and the clinical approach to patient management and therapeutic options for lipodystrophy and lipid dysmetabolism is evaluated.
If the histogenesis of the extragonadal germ cell tumor is a still debatable subject, its clinical diagnosis remains a question of no immediate solution. In fact, only the keen histologic evaluation of microfocuses and/or scar tissue in the testis, possibly on the guide of US finding, could give the answer about the primitiveness or not of the extragonadal neoplasia. Which implies, of course, some problems of compliance on the part of young locally symptomless men, especially on the ground of possibly bilateral involvement.
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We report a case of the Churg-Strauss syndrome with bilateral ureteral stenosis, secondary obstructive uropathy and anuria. The literature regarding urological implications of this disease is reviewed, and the surgical and medical management of our case is detailed.
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By real-time ultrasounds through an intra-vesical probe, bladder mucosal features, wall thickness and external profile, as well as their pathological changes, are beautifully imaged; therefore, the role of this echographic technique in the clinical pre-treatment assessment of tumor local staging is expected to be accurate and reliable, accordingly to the first results by Holms and co-w. We have intended to verify the value of the method, by comparing the pre-treatment staging by the more traditional non-invasive clinical procedures plus intra-vesical sonography to the pathological staging (pT) from the removed tumor samples. Our preliminary results are herein presented, from which the overall accuracy of this staging approach seems to be confirmed and a wider experimentation to be justified.
The rules for a diagnostic approach to non-acute prostatitis, as applied during a one-year trial in this Division of Urology, are reviewed and their results on a clinical ground of 150 cases are discussed. In fact, this clinical conditions is apt to present often some problems, as far its cure is concerned, due to its variety of symptoms, and not seldom to un-correct previous therapeutic approach, for defect of a precise diagnostic appraisal.
Repetitive surgery on the upper urinary tract calls for extensive and sometimes difficult dissection, therapy exposes to the risk of vascular and nervous injury, as far as tissue trophism is concerned, moreover to secondary severe perivisceral fibrosis. The ureter is particularly liable to such early or late damages. The use of a self-retaining stent, even for a long period of time, and of a pedicle omental graft wrapping ensures a better recovery and the prevention of fistulae or strictures from secondary retroperitoneal fibrosis.
To assess the presence of Chlamydia trachomatis in nonacute abacterial prostatitis 30 patients with urethral cultures positive for Chlamydia trachomatis underwent microbiological studies, including cultures of transrectal aspiration biopsies of the prostate. Chlamydia trachomatis was isolated from 10 of the prostatic specimens (33 per cent). In 3 cases a nonspecific cytopathogenic effect caused the destruction of the tissue cultures. Our findings demonstrate that Chlamydia trachomatis may cause ascending infections of the prostate and that this microorganism may have an etiological role in the pathogenesis of nonacute abacterial prostatitis.
On the ground of the clinical experience of transurethral resection of the benign hypertrophy of the prostate performed in the Division of Urology during the last ten years, the technical aspects and problems of the procedure are discussed, chiefly the low-pressure irrigation of the operative field for the prevention of vesical damages and of the water-syndrome. The choice of the transurethral technique is dependent chiefly on the weight of the adenoma, on the duration of its removal and the related problems; it is also dependent on the availability of both proper instrumentation and operators. The lesser all-over surgical traumatism and blood loss, the precocious getting out of bed, the shortening of hospitalisation make T.U.R. particularly suitable for high risk patients. To conclude with, the clinical, personal and social advantages of this procedure depend on the correctness of its choice following the criteria which have been referred to.
Twenty five patients with C.N.S. diseases (parkinsonism and multiple sclerosis) have been studied by means of electrocystouretromanometry and electromyography. Cases with patent urological causes of vesico-sphincteric functional impairment have not been included. In multiple sclerosis urodynamic changes, chiefly detrusor hyper-reflexia, have been registered in 75% of cases, EMG sphincter activity disturbances in 85%. Respectively, 90% of cystomanometries and 54% of EMG sphincter activities showed changes in Parkinsonism. The precise assessment of the individual specific urodynamic change seems to allow a rationally better therapeutic perspective.
160 cases of neoplasm of the kidney in the adult are reviewed, with regard to to-day knowledge of problems not yet resolved in the field both of diagnosis and treatment. As diagnosis is concerned, the primary role of angiography is confirmed, though the alternative and/or complementary role of ultrasounds and densitometry cannot be overlooked. As for treatment, the primary choice seems to remain surgery, in which regard a new meaning of radicality and operability is on way to develop, due to improvement of diagnostic means and, in lesser grade, of complementary treatments.
The clinical significance of strain gauge plethysmography in pampiniform plexus pathology has been explored, with the assumption that there should be some analogy with lower limb venous conditions in which this examination gives valuable results. The first findings seem to confirm that strain gauge plethysmography affords, in varicocele, some reliable evaluations on venous drainage insufficiency, capacity and resiliency of spermatic venous bed as well as on functional results of surgical treatment.