Continuing invariant solutions towards the turbulent flow.

A new mathematical framework is proposed for characterizing the coherent motion of fluctuations around a mean turbulent channel flow. We search for statistically invariant coherent solutions of the unsteady Reynolds-averaged Navier-Stokes equations written in a perturbative form with respect to the turbulent mean flow, using a suitable approximation of the Reynolds stress tensor. This is achieved by setting up a continuation procedure of known solutions of the perturbative Navier-Stokes equations, based on the continuous increase of the turbulent eddy viscosity towards its turbulent value. The recovered solutions, being sustained only in the presence of the Reynolds stress tensor, are representative of the statistically coherent motion of turbulent flows. For small friction Reynolds number and/or domain size, the statistically invariant motion is almost identical to the corresponding invariant solution of the Navier-Stokes equations. Whereas, for sufficiently large friction number and/or domain size, it considerably departs from the starting invariant solution of the Navier-Stokes equations, presenting spatial structures, main wavelengths and scaling very close to those characterizing both large- and small-scale motion of turbulent channel flows. This article is part of the theme issue 'Mathematical problems in physical fluid dynamics (part 2)'.

Rapid path to transition via nonlinear localized optimal perturbations in a boundary-layer flow.

Recent studies have suggested that in some cases transition can be triggered by some purely nonlinear mechanisms. Here we aim at verifying such an hypothesis, looking for a localized perturbation able to lead a boundary-layer flow to a chaotic state, following a nonlinear route. Nonlinear optimal localized perturbations have been computed by means of an energy optimization which includes the nonlinear terms of the Navier-Stokes equations. Such perturbations lie on the turbulent side of the laminar-turbulent boundary, whereas, for the same value of the initial energy, their linear counterparts do not. The evolution of these perturbations toward a turbulent flow involves the presence of streamwise-inclined vortices at short times and of hairpin structures prior to breakdown.

Total abdominal hysterectomy: a randomized study comparing two techniques.

BACKGROUND: Abdominal hysterectomy is the most frequent operation performed by gynecologists. The most commonly used techniques are intrafascial, extrafascial and supracervical hysterectomy; in our department we mainly use the first method. A variant of this technique, because during the operation we use only an Allis clamp, simplifies the operation and maintains certain anatomical relationships between neighbouring pelvic structures. METHODS: To compare two different surgical techniques between 1/1/1991 and 31/12/95, 262 women were randomized pre-operatively: 133 by the intrafascial technique of Richardson and 129 by the variant hysterectomy technique. The difference between the two techniques (Richardson versus variant hysterectomy technique), as performed in our department, was investigated regarding the clamping of uterine vessels, the resection of uterosacral and cardinal ligament. The two-tailed student test was used for continuous data and chi2 analysis for discrete data. RESULTS: Less blood loss occurred in the variant than in the Richardson group (P<0.01) and no intrasurgical complications occurred as compared to one case of ureter lesion in the Richardson group. There were no differences in the number of days of hospitalization. No particular post-surgical complications occurred in the follow-up period, which has now elapsed. After 36 months of follow-up the variant group showed a reduced incidence (not significant) of vaginal vault prolapse. The patients who underwent the variant hysterectomy technique reported better compliance with regard to sexual intercourse and urinary function than the Richardson group. CONCLUSION: We conclude that the variant hysterectomy technique is as valid as the Richardson technique, giving the surgeon the possibility of maintaining certain anatomical relationships between neighbouring pelvic structures. It also has minor delayed complications.

Posterior scleritis: ultrasound findings in two cases.

Two cases of posterior inflammatory scleritis are described. The authors show the echographic findings, pointing out the helpfulness of diagnostic ultrasound and the crucial role in monitoring these diseases with A scan examinations to obtain clear results of therapy, even if subjective symptoms disappear.

Inhibition of ovulation with transdermal estradiol and oral progestogens in perimenopausal women.

The effects of 6 months of combined hormone therapy with transdermal estradiol (0.05 mg/day x 21 days) and different oral progestogens (10 mg/day medroxyprogesterone acetate [MPA] in the last 12 days, 10 mg/day dihydrogesterone in the last 12 days, and 50 mg/day cyproterone in the first 10 days), on menopausal symptoms and hypothalamo pituitary-ovarian function were studied in normal perimenopausal women. The study included 38 perimenopausal women, aged 43-49 years, with regular cycles of 26-32 days in length and menopausal symptoms. Endocrine status was determined by assay of basal levels of gonadotropins (LH, FSH), E2, and P every week until menstrual bleeding, before and during the first month of therapy. Plasma levels of LH and FSH were suppressed in the first month of therapy while E2 had a mean value of 45 +/- 12 pg/ml. Ultrasound examination and low levels of P indicated a complete block of ovulation and hypothalamo-pituitary-ovarian activity. All women reported the disappearance of vasomotor symptoms and nocturnal sweating. Transdermal estradiol and oral progestogens were well tolerated. This study shows that combined hormone therapy with low doses of transdermal estrogen patches and different oral progestogens reduces menopausal symptoms and also safeguards against unwanted pregnancies in the perimenopausal period.

Transdermal estrogen replacement therapy in normal perimenopausal women: effects on pituitary-ovarian function.

The effects of 6 months of hormone replacement therapy by transdermal estradiol patches (0.05 mg/day for 21 days) and oral progestogens (10 mg/day for 10 days) on hypothalamic-pituitary-ovarian function was evaluated in 32 perimenopausal women, aged 42-47 years, with irregular anovulatory cycles and menopausal symptoms. Hormone levels evaluated on the 8th and 24th day of the cycle preceding therapy showed follicle-stimulating hormone (FSH) levels above 15 mIU/ml, estradiol less than 45 pg/ml and progesterone less than 800 pg/ml. During therapy, there was an improvement in menopausal symptoms, a decrease in luteinizing hormone (LH) and FSH levels, an increase in estradiol levels and the transdermal patches were well tolerated. At the end of therapy, 19 women continued to have regular ovulatory cycles with progesterone levels similar to those in luteal phase. FSH and LH concentrations were significantly lower than before therapy. This study shows that hormone replacement therapy not only improves menopausal symptoms but may also restore the hypothalamic-pituitary-ovarian function.

Krukenberg tumor in pregnancy with virilization. A case report.

A rare case of virilizing ovarian Krukenberg tumor of gastric origin in pregnancy is described. In spite of resection of the cancerous ovary, and primary gastric adenocarcinoma, followed by vigorous post-surgical chemotherapy, the 40-year woman died 31 months after diagnosis. The authors review another nine similar cases found in the literature. Such a diagnosis should be considered in the differential diagnosis of virilization in pregnancy.

Leiomyosarcoma of the uterus metastatic to brain: a case report and a review of the literature.

Central nervous system metastases are an unusual sequela of uterine sarcomas. A single brain metastasis from a leiomyosarcoma occurred in a 60-year-old woman, 6.5 years after hysterectomy and more than 2 years following the diagnosis of bilateral lung metastases, treated by combination chemotherapy. After resection of the cerebral metastasis, she was treated with brain radiation therapy and survived 2.5 years. Only seven other cases of uterus leiomyosarcoma metastatic to the brain have been published.

A new procedure in the surgical treatment of large incisional ventral hernias with the use of Dexon Mesh.

A new procedure in the surgical treatment of large incisional ventral hernias is described. It is based on the use of enlarged relaxation incisions of the abdominal fascia on both sides of the hernia to perform a direct suture of the posterior and superficial fascial layer of the hernia defect without tension. Extensive fascial defects after enlarged side relaxation incisions should be reinforced to prevent a weakness of the ventral abdominal wall. The best material may be a resorbable knitted mesh.

Progression of optic neuritis to multiple sclerosis: a prospective study in an Italian population.

We prospectively studied 40 patients with uncomplicated optic neuritis (ON) to determine the risk of subsequent multiple sclerosis (MS). All patients were followed for at least 12 years. Ten patients (25%) developed MS. Seven of these 10 patients developed MS within 2 years. Both sexes were at high risk if ON occurred between the ages of 21 and 40. There was an overall increased risk of MS with recurrent ON. The course of MS appeared to be fairly benign during the period of observation.

The incidence of optic neuropathy in 84 patients treated with ethambutol.

The authors examined 84 patients with pulmonary TBC treated with ethambutol (25 mg/Kg/die). The patients were divided into two groups on the basis of zinc plasma levels: 53 patients with zinc plasma level greater than 1 mg/l and 31 with zinc plasma levels less than 0.7 mg/l. The two groups underwent periodical follow-up of visual acuity, fundus, color vision (Fransworth 100 HUE) and visual field. The checks were monthly on the first group and fortnightly in the second. Eight patients presented signs of optic neuropathy. Patients with lower zinc plasma levels showed a higher percentage of optic neuropathy.

Immunohistochemical study of ten cases of argyrophilic carcinoma (carcinoid) of the breast.

The significance of argyrophilia in human breast cancer is still a controversial issue. We tested immunohistochemically 10 cases of argyrophilic carcinomas of the breast and found evidence of immunoreactivity with neuroendocrine markers: chromogranin, NSE, gastrin, insulin and bombesin. Argyrophilia was demonstrated in breast cancers of the usual types and was found to be related to the secretory activity of neoplastic cells. Unfortunately, no adequate follow-up data are available to clarify the natural history of argyrophilic breast cancer. A clinical treatment different from that of conventional breast cancer is not at present justified.

[Evoked potentials in idiopathic optic neuritis. Possibilities of early diagnosis of demyelinating disease]. / I potenziali evocati nelle neuriti ottiche idiopatiche. Possibilità di diagnosi precoce di malattia demielinizzante.

The AA. examined 36 uncomplicated ON (Optic neuritis) observed from 1-1-1970 to 31-12-1980. An ophthalmological, neurological, and electrophysiological test (VEP, SEP, BAER) is made on this patients from 1-1-1986 to 31-3-1986. The importance of the electrophysiological examination is evaluated to recognize subclinical Multiple Sclerosis.

Myasthenia gravis and recurrent retrobulbar optic neuritis: an unusual combination of diseases.

A case is presented that illustrates the unusual concurrence of both myasthenia gravis and recurrent retrobulbar optic neuritis. The association of optic neuritis with myasthenia gravis might support the idea that there is a disorder of immune function in optic neuritis.

[Retrobulbar optic neuritis as an initial symptom of multiple sclerosis. Results of a prospective study]. / La neurite ottica retrobulbare come sintomo d'esordio della sclerosi multipla. Risultati di uno studio prospettico.

40 patients with idiopathic optic neuritis (ON) between 1st January 1967 and 31st December 1977 have been checked again from oculistic and neurological point of view between 1st January and 31st March 1983. 10 of 40 examined patients (25%) are found suffering from multiple sclerosis (MS) at the time of check up. Our research points out that idiopathic ON evolutive risk towards MS is greater in females, in people between 20 and 40 years old, in people with one or more relapses as well as in people with neurological microsymptoms at the time of ON.