A system has been constructed and evaluated for generating aerosols from combustion or pyrolysis of various cross-linked polymers. The system consists of an aerosol generator and an aerosol chamber with a sampling compartment designed for various samplers and sampling probes. A geared electric motor assembly is used to lower a polymer strip into the controlled atmosphere of a quartz-lined furnace. The polymer used in this investigation was a polyurethane foam (PUF) based on toluene diisocyanate (TDI). Combustion of the PUF was conducted in filtered air at a temperature of 300 degrees C. The particle number concentration of the generated aerosol was measured by light scattering in the particle size range from 0.1 micron to greater than 5 microns. Air samples were collected periodically in impinger flasks using dibutylamine (DBA) in toluene as derivatization reagent. The TDI-DBA derivatives from the impinger samples were analyzed with high performance liquid chromatography. The aerosol generating system was found to generate a stable, reproducible, and predictable concentration of particles and TDI monomer. Three partial least squares models were created to evaluate the generator. The investigated responses were the TDI concentration, the particle number concentration, and the stability of the particle number concentration during the generating process. The factor with most impact on the concentrations of the generated aerosol was found to be the interaction between linear feeding rate of the polymer strip and the flow rate of combustion gas. For stability the linear feeding rate was the most important.

Aerosols↗

PubMedDate not supplied

Adaptation to vibratory perturbations in postural control.

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Adaptation, Physiological↗

PubMedDate not supplied

Significance of pressor input from the human feet in lateral postural control. The effect of hypothermia on galvanically induced body-sway.

The significance to human postural control of pressor information from the feet was investigated during vestibular disturbance in seven normal subjects who were exposed to bipolar biaural galvanic stimulation of the vestibular nerves before and after their feet were anaesthetized with hypothermia. The increase in body sway in the lateral plane induced by the galvanic stimulus was enhanced when the feet were anaesthetized, and adaptation of postural control to the galvanic stimulus was delayed. It is concluded that pressor information from the feet contributes significantly to postural control in humans and is important in compensating for vestibular disturbance.

Adaptation, Physiological↗

PubMedDate not supplied

Galvanically induced body sway in the anterior-posterior plane.

Anterior-posterior body sway was evoked with monopolar bi-aural galvanic stimulus of the vestibular nerves in normal subjects and recorded with a force platform, two experiments being conducted. In an experiment of paired design, 9 normal subjects showed an increase in anterior-posterior sway as compared with lateral sway when exposed to the stimulus. In a second experiment another group of 10 normal subjects were exposed to a galvanic stimulus between a neck electrode and two electrodes placed on the arms, but there was no change in the relationship between anterior-posterior and lateral body sway. It is concluded that monopolar galvanic stimulus of the vestibular nerves can induce anterior-posterior body sway, a phenomenon which can be utilised to investigate the vestibulo-spinal contribution in postural control in the anterior-posterior plane.

Adult↗

PubMedDate not supplied

Significance of pressor input from the human feet in anterior-posterior postural control. The effect of hypothermia on vibration-induced body-sway.

The importance to postural control of the mechanoreceptors of the soles was investigated in thirteen healthy subjects. Body-sway velocity was evaluated before and after exposing the subject's feet to hypothermia, and when calf muscles were exposed to vibration at frequencies between 20 and 100 Hz. Subjects were tested both with eyes open and closed. Body-sway velocity was found to increase significantly during hypothermia of the feet. The difference in body-sway between hypothermal and normothermal conditions was less prominent when the subject's eyes were open though the difference was significant in both cases. The present results indicate the importance of the mechanoreceptors of the soles to postural control and elucidate their interaction with compensatory visual input in maintaining postural control. These findings also suggest, that factors affecting pressor input should be taken into consideration when assessing patients with complaints of dysequilibrium.

Adult↗

PubMedDate not supplied

Preoperative high type I collagen degradation marker ICTP reflects advanced breast cancer.

Type I collagen synthesis (PINP, PICP) and degradation (ICTP) markers were analysed from preoperative serum samples of 138 women with breast cancer (BC), 94 women with benign breast disease (BBD) and 100 healthy controls to evaluate the levels of these markers and the stage of BC at the time of diagnosis. We also compared the clinical utility of these markers in detecting BC with CA15-3 and CEA. The mean value of ICTP was statistically significantly elevated in the BC group (p < 0.001), as compared with the control group, but the elevated values in BC group were due to stage IV disease. The sensitivity of ICTP in detecting BC was 0.23, which was equal with CA15-3(0.24) or CEA(0.23). The sensitivity of both PICP and PINP for diagnosing BC was poor, but a tendency to higher serum levels of PINP and low PICP/PINP ratio was detected in patients with advanced stage IV disease. These results indicate that high preoperative serum levels of ICTP are associated with advanced BC, but like CA15-3 and CEA, its clinical value in diagnosing purpose is poor.

Biomarkers, Tumor↗

PubMedDate not supplied

Review--antibiotic treatment in inflammatory bowel disease: rifaximin, a new possible approach.

The etiology of inflammatory disease is still unknown, but a body of evidence from clinical and experimental observation indicates a role for intestinal microflora in the pathogenesis of this disease. Reduction of microflora using antibiotics, bowel rest and fecal diversion decreases activity in Crohn's disease and in ulcerative colitis. Several trials have been carried out on the use of antibiotic treatment in patients with active ulcerative colitis with contrasting results. A number of trials have been carried out using Rifaximin, a non-absorbable broad-spectrum antibiotic, confirming the absence of systemic bioavalaibility of the drug even when administered at very high doses and for prolonged periods. It may therefore be useful in treatment of ulcerative colitis and pouchitis, since its absorption through inflamed mucosa is negligible, it maintains a topical action without systemic effects and the lack of resistant bacterial strains may allow prolonged and repeated treatments.

Anti-Bacterial Agents↗

PubMedDate not supplied

Prognostic significance of TGF-beta 1 and TGF-beta 2 expressions in female breast cancer.

A series of 273 breast cancer biopsies were analysed immunohistochemically for the expression of transforming growth factor beta-1 (TGF-beta 1) and beta-2 (TGF-beta 2) as related to standard prognostic factors and patient survival. TGF-beta 1 expression was found in 160/273 (59%) and TGF-2 in 110/273 (40%) of tumour specimens. Both isoforms were expressed in 89/273 (33%) of cases. TGF-beta 1 alone was expressed in 71/273 (26%) of cases and TGF-beta 2 alone was expressed in 19/273 (7%) of cases. The expression of TGF-beta 1 and TGF-beta 2 were both uniformly related to some other favourable prognostic factors. The expression of TGF-beta 2 without the expression of TGF-1 was significantly related to favourable disease outcome. The result of this study is in agreement with the previous studies of TGF-beta mRNA and also in vitro studies, but the result differs from some previous immunohistological studies. This study also suggests that the expression of TGF beta may have independent prognostic value over the expression of TGF-beta 1.

Breast Neoplasms↗

PubMedDate not supplied

Dizziness of suspected cervical origin distinguished by posturographic assessment of human postural dynamics.

Useful clinical tests are lacking for the controversial entity "cervical vertigo". In earlier studies patients assumed to suffer from cervical vertigo or dizziness manifested disturbed postural control as compared to healthy subjects, but were hard to distinguish from patients with other balance disorders. Using posturography in which stance was perturbed by a vibratory stimulus applied towards the calf muscles, we studied 16 consecutive patients with recent onset of neck pain and concomitant complaints of vertigo or dizziness, but normal findings at otoneurological examination and electronystagmography; 18 patients with recent vestibular neuritis; and 17 healthy subjects. We performed system identification of a model of the control of upright human stance, using the vibratory stimulus as input and the recorded body sway as output. According to values for the three normalized parameters of the transfer function of the model (i.e., swiftness, stiffness, and damping), cervical vertigo patients were distinguished both from healthy subjects (P < 0.001), and from vestibular neuritis patients (P < 0.001). It was also possible to distinguish the vestibular neuritis group from the group of healthy subjects (P < 0.01). The results show disturbed postural control in patients with cervical vertigo to differ from that in patients with recent vestibular neuritis, and indicate posturographic assessment of human posture dynamics to be a possible future tool for use in diagnosing cervical vertigo.

Adult↗