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OBJECTIVE: The aim of this study was to determine postural responses before and after a vestibular rehabilitation program (VRP) in 14 patients with central vestibular disorders (CVD). MATERIAL AND METHODS: The confidence ellipse (CE) of the center of pressure distribution area and the sway velocity (SV) were the parameters used for the quantitative assessment of postural control (PC). These two parameters were analyzed before and after a VRP for two visual conditions. Behavioral postural responses were studied by means of the time-frequency scalogram using wavelets and the sway frequency content was measured in arbitrary units of energy density. RESULTS: Ten patients showed a significant decrease in the CE and SV after the rehabilitative treatment, thus improving their PC. Seven of these patients were assessed again after a period of 12 +/- 5 months, during which they had not received any physical training. All of them showed increases in the CE and SV, indicating an impairment of PC. CONCLUSIONS: Many CVD patients damage the neural mechanisms involved in retaining the plastic changes in the PC parameters after rehabilitative treatment. Continuation of training may be necessary in order to maintain the improvement in PC obtained with a VRP.

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In order to assess the influence of visual stimulation in the triggering of imbalance and falls in the elderly population, the postural responses of 18 elderly patients with central vestibular disorders and clinical evidence of instability and falls were studied while receiving different types of visual stimuli. The stimulation conditions were: (i) no specific stimuli; (ii) smooth pursuit with pure sinusoids of 0.2 Hz as foveal stimulation; and (iii) optokinetic stimulation (OK) as retinal stimuli. Using a platform AMTI Accusway platform, the 95% confidence ellipse (CE) and sway velocity (SV) were evaluated with a scalogram using wavelets in order to assess the relationship between time and frequency in postural control. Velocity histograms were also constructed in order to observe the distribution of velocity values during the recording. A non-homogeneous postural behavior after visual stimulation was found among this population. In five of the patients the OK stimulation generated: (i) significantly higher average values of CE ( > 3.4+/-0.69 cm2); (ii) a significant increase in the average values of the SV ( > 3.89+/-1.15 cm/s) and a velocity histogram with a homogeneous distribution between 0 and 18 cm/s; and (iii) a scalogram with sway frequencies of up to 4 Hz distributed in both the X and Y directions (backwards and forwards and lateral) during visual stimulation with arbitrary units of energy density > 5. These three qualitative and quantitative aspects could be "markers" of visual dependence in the triggering of the mechanism of lack of equilibrium and hence falls in some elderly patients and should be considered in order to prevent falls and also to assist in the rehabilitation program of these patients.

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Patients with different vestibular disorders exhibit changes in postural behaviour when they receive visual stimuli, reproducing environmental stimulation. Postural control was studied using an AMTI Accusway platform, measuring the confidential ellipse (CE) and sway velocity (SV). Postural responses were recorded according to the following stimulation paradigm: i) without specific stimuli; ii) smooth pursuit with pure sinusoids of 0.2 Hz (foveal stimulation); and iii) optokinetic stimulation (retinal stimuli). Patients with central vestibular disorders (CVD), cerebellar damage and unilateral peripheral vestibular lesions (UPVL) in asymptomatic periods were studied. A group of normal subjects was studied as control. Signal processing was done with a scalogram by wavelets in order to observe the relation between time and frequency in postural control. While patients with CVD and cerebellar disease showed a significant increase in CE and SV in the three conditions of the paradigm compared to the normal group, the patients with UPVL showed no change. Wavelets processing showed that the main sway occurs in the Y axis (antero-posterior) and below at 0.4 Hz in normal subjects, while the CVD and cerebellar patients showed sway frequencies in both the X and Y axes. The clinical implications of these findings are discussed.

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The relationships between experimentally induced deciduoma formation, circulating estradiol (E) and progesterone (P) levels and alterations in uterine blood flow (UBF) were studied between days 4 and 15 of pseudopregnancy (PSP: day 0 = ovulation) in rats. Blood flow was measured with an electromagnetic blood flow monitor and serum analyzed for E and P levels by radioimmunoassay. Neither uterine trauma on day 4 of PSP nor the site of trauma had any direct influence on altering UBF. A dramatic increase in UBF occurred in response to stromal proliferation on days 5-6 and continued to remain above sham-operated control levels through day 9. These vascular changes correlated temporally with the day 9 peak in uterine weight resulting from deciduoma formation. Both uterine weight and vascular fluctuations in deciduoma-bearing rats were related to the cyclic changes in E/P ratios between days 5 and 8 of PSP. A decline in UBF preceded deciduoma regression between days 9 and 15 of PSP. These results suggest that an increase in UBF is causally associated with the formation and maintenance of deciduoma in the PSP rat and that deciduoma regression may result from a subsequent decline in UBF rates. Both factors may be directly dependent on fluctuating E/P ratios.

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To determine if oxytocin and estradiol were effected by pelvic neurectomy (PN), utero-ovarian vein blood was collected from PN rats during the preparturient period and assayed for these hormones. Radioimmunoassayable oxytocin levels were not significantly different in any groups of sham operated (S) or PN animals on days 21 and 22 or PN animals on days 23 and 24. Estradiol (E2) levels rose significantly on day 22 in S animals but there was no significant change in E2 in PN rats throughout the time period studied, although E2 levels were generally high. These results indicate that the blocked parturition characteristic of PN animals cannot be attributed to altered oxytocin levels. The lack of a significant E2 surge on day 22 in PN rats may contribute to the failure of utero-ovarian vein prostaglandin F levels to rise in these animals during the preparturient period.

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Mouse peritoneal macrophages were incubated with varying amounts of heat-inactivated fetal calf serum (FCS) and treated with diazepam at the concentrations of 0.5 and 5.0 mug/ml. These macrophage preparations demonstrate that the capacity for synthesis and release of prostaglandins (PGs) E2, F2 alpha, 6-keto-PGF1 alpha and thromboxane TX(B2) is: (a) sensitive to the concentration of FCS in the culture medium, and (b) altered in the presence of diazepam. A radioimmunoassay for 6-keto-PGF1 alpha is also reported. The efficiency of extraction of PGE2 and 6-keto-PGF1 alpha from buffer or plasma samples was greatly improved when a petroleum ether/ether (1/1) solvent system was employed.

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Walker 256 tumours grafted under the left kidney capsules in rats showed enhanced growth following daily treatment with diazepam 500 micrograms (1.7 mg/kg body weight) subcutaneously but not with 1250 micrograms. Thromboxane B2 (the metabolite of TXA2) levels in venous drainage from both the tumour bearing left kidney and from the right control kidney were reduced significantly in all the three groups of tumour bearing rats. Plasma PGE2 was higher in the venous drainage from the tumour bearing left kidney than from the right control kidney. Significantly higher levels were measured following 500 micrograms but not after 1250 micrograms of diazepam. Plasma PGF2 alpha on the other hand, was lower in the plasma from the tumour bearing kidney and was further lowered in animals receiving diazepam treatment.

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The growth of the R3230AC mammary carcinoma was studied in female Fisher 344 rats that were treated with diazepam. Diazepam at 250 micrograms/animal/day (2.5 mg/kg body weight) and 500 micrograms/day was administered for 4 weeks, starting 2 days before subcutaneous transplantation of uniform pieces of the tumour. Tumour size was significantly increased in the group receiving 250 micrograms but was below the levels observed in the saline treated controls in those given 500 micrograms diazepam. Plasma PGE2 and PGF2 alpha concentrations were comparable in control and diazepam treated animals.

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