Adsorptive removal of phosphate from aqueous solutions using raw and calcinated dolomite

This study explored the feasibility of utilizing raw and calcinated dolomite under CO2 atmosphere for phosphate removal in laboratory experiments. The experimental work emphasized the evaluation of phosphate adsorption characteristics of this adsorbent material. Studies were conducted to delineate the effect of contact time, initial phosphate concentration, temperature, pH, stirring speed, adsorbent dose and calcination temperature. Phosphate removal decreased with increasing temperature and slightly increased with increasing of pH. The observed decrease in the adsorption capacity with increase of the temperature from 20 to 40 and to 60 degrees C indicates that the low temperatures favor the phosphate removal by adsorption onto dolomite. Phosphate removal was seen to decrease with increasing calcination temperature due to the structural changes occurring in the structure and pore size distribution of dolomite samples during calcination. The experimental data obtained were applied to the Freundlich, Langmuir, BET, Halsey, Harkins-Jura, Smith and Henderson isotherm equations to test the fit of these equations to raw and calcinated dolomite samples. By considering the experimental results and adsorption models applied in this study, it can be concluded that adsorption of phosphate occurs predominantly through physical interactions, and the dolomite sample has a heteroporous structure. The large values of the constants for Henderson equation and the high value of y(m) obtained from BET equation indicate the microporous structure is more stable in raw and calcinated dolomite samples.

Is Low Blood Magnesium Level Associated With Hemodialysis Headache?

OBJECTIVE

The aim of this study was to evaluate the prevalence, demographic, clinical features, and possible risk factors for hemodialysis headache (HDH).

BACKGROUND

HDH has been recognized for many years, but the pathophysiology of this condition is not known. High arterial blood pressure, decreased serum osmolality, sodium washout, and high blood urea nitrogen level are reported risk factors for HDH. Low serum magnesium (Mg) level is known to cause some types of headache, including migraine (menstrual migraine in particular), tension-type headaches, and cluster and posttraumatic headaches. Low Mg has also been reported in HDH patients.

METHODS

A total of 250 hemodialysis (HD) patients were questioned about problems with headache. Of these, 75 were diagnosed with HDH according to the revised International Headache Society criteria for 2003. Eighty age- and sex-matched HD patients without HDH were selected as a control group. For each HDH and control subject, arterial diastolic and systolic blood pressure, body weight, and serum levels of sodium, blood urea nitrogen, creatinine, and Mg were measured before and after one HD session. Urea reduction rate and ultrafiltration were determined. Serum levels of phosphorus, calcium, albumin, and parathormone were measured only before the session. Findings in the HDH and control group were statistically compared.

RESULTS

As noted, 75 (30%) of the total 250 HD patients surveyed were diagnosed with HDH. The mean headache duration in this group was 5.17 +/- 5 hours. Vertex location, bilateral headache, dull nature, and moderate severity were the most prevalent features of HDH. There were no statistically significant differences between the HDH and control groups with respect to causes of end-stage renal disease. There were no significant differences between the HDH and control groups with respect to predialysis values for blood urea nitrogen, body weight, and arterial blood pressure (P > .05), and the same was true for comparisons of the postdialysis values for these parameters. The mean predialysis sodium level in the HDH group was higher than in the control group (P= .003). Both the mean predialysis and mean postdialysis Mg levels in the HDH group were significantly lower than the corresponding levels in the control group (P= .05 and P= .02, respectively).

CONCLUSIONS

The results suggest that low blood Mg level and high blood sodium level may be risk factors for HDH. Magnesium supplementation may help patients with HDH whose serum Mg levels are found to be low.

Acquired port-wine stain related to acoustic neuroma

Port-wine stains are frequently seen congenital vascular malformations consisting of ectatic dermal capillaries. Acquired port-wine stain that develops later in life is an uncommon vascular lesion that is morphologically identical to a congenital port-wine stain. In the majority of acquired port-wine stains, the aetiology is unknown, but trauma is an important causative factor. Other proposed aetiologies include chronic sun exposure, hormonal changes, frostbite injury, obstruction of the peritoneovenous shunt, herpes zoster infection, and cerebral arteriovenous malformation. Here we report the first case of a patient who had an acquired port-wine stain related to a solid brain tumour.

Mucormycosis presenting with painful ophthalmoplegia

Mucormycosis is a rare fungal infection that can involve the sino-orbito-cerebral region. Sino-orbito-cerebral mucormycosis is most common in patients who are immunocompromised or have diabetes mellitus, severe malnutrition or burns. This condition can be fatal if it is not diagnosed early and treated aggressively. This article presents 4 cases of mucormycosis, including 2 with orbital apex syndrome, 1 with cavernous sinus syndrome, and 1 with multiple cranial nerve involvement. All of the patients were presented with painful ophthalmoplegia. The predisposing factors for mucormycosis included diabetes mellitus (three patients) and chronic leukemia (one patient). In all cases, mucormycosis was diagnosed by examining endoscopic sinus drainage material and was treated with surgical debridement and amphotericin B. Two patients with central nervous system involvement died. The others have survived, but still exhibiting various neurologic abnormalities after aggressive treatment. Patients with mucormycosis rarely present with orbital apex syndrome. The possibility of mucormycosis should be investigated in any patient with painful ophthalmoplegia, and prompt otorhinolaryngologic examination is recommended to ensure rapid diagnosis and treatment.

Kinetic modeling of liquid-phase adsorption of phosphate on dolomite

The adsorption of phosphate from aqueous solution on dolomite was investigated at 20 and 40 degrees C in terms of pseudo-second-order mechanism for chemical adsorption as well as an intraparticle diffusion mechanism process. Adsorption was changed with increased contact time, initial phosphate concentration, temperature, solution pH. A pseudo-second-order model and intraparticle diffusion model have been developed to predict the rate constants of adsorption and equilibrium capacities. The activation energy of adsorption can be evaluated using the pseudo-second-order rate constants. The adsorption of phosphate onto dolomite are an exothermically activated process. A relatively low activation energy and a model highly fitting to intraparticle diffusion suggest that the adsorption of phosphate by dolomite may involve not only physical but also chemisorption. This was likely due to its combined control of chemisorption and intraparticle diffusion. However, for phosphate/dolomite system chemical reaction is important and significant in the rate-controlling step, and for the adsorption of phosphate onto dolomite the pseudo-second-order chemical reaction kinetics provides the best correlation of the experimental data.

[Endovascular treatment of vertebral artery origin stenosis in high risk patients]

PURPOSE

Atherosclerotic stenosis of the vertebrobasilar system most commonly occurs at the vertebral artery origin. Stenting of these stenotic lesions in combination with antithrombotics with or without anticoagulants is a safe and effective treatment method. The purpose of this study is to present the results of vertebral artery origin stenting in 14 high-risk patients.

MATERIALS AND METHODS

Significant vertebral artery origin stenosis was treated with primary stenting in 14 patients, aged between 58 and 74 years (mean, 66+/-5.3 years). Eleven patients were male, and three were female. Vertebral artery stenosis was detected in eight patients prior to coronary artery surgery, and in six patients after a posterior system stroke or during evaluation of a vertebrobasilar insufficiency. All stenosis were successfully treated with stent placement. Except one patient who had a left posterior cerebral artery infarction, all patients had an uneventful procedure without any complication. Third-month and sixth-month clinical and color Doppler follow-up examinations were available in ten patients, and 12th-month control angiography performed in three patients did not show stent restenosis. None of the patients had new neurologic deficit during the follow-up.

CONCLUSION

Vertebral artery origin stenoses are one of the most common causes of vertebrobasilar stroke. In the presence of concomitant cerebral artery stenosis or systemic disorders, patients are under high risk even if they are on medical therapy. Primary stenting combined with medical treatment is a safe and effective treatment modality.

Determination of adsorptive properties of clay/water system: methylene blue sorption

In this study, adsorption of methylene blue onto clay was investigated. The effect of adsorption time and temperature on the adsorption process was studied. To reveal the adsorptive characteristics of the clay studied, porosity and BET surface area measurements were made. It was observed that the adsorption capacity decreases with increasing temperature, and adsorption equilibrium was attained within 1 h. It was found that the data fit well to Langmuir, Halsey, Henderson, and Harkins-Jura models but experimental data deviate significantly from BET and Freundlich models at especially high concentrations. Furthermore, isosteric adsorption enthalpy and entropy are calculated as -7.99 kJ mol(-1) and 25.41 JK(-1)mol(-1), respectively.

Voice analysis and videolaryngostroboscopy in patients with Parkinson's disease

Parkinson's disease (PD) is clinically characterized by a resting tremor, bradykinesia, cogwheel phenomenon, rigidity, disorder of postural reflexes and especially changes in voice and speech. We studied 30 PD patients who were treated with dopamine and 20 normal subjects as the control group. The parameters of vocal fold edges, glottal closure, vertical levels of cords, amplitude of vibration, mucosal wave, vibratory behavior, phase symmetry, ventricular folds and movements, periodicity, arytenoids and thick mucous were evaluated by videolaryngostroboscopy. The Unified Parkinson's Disease Rating Scale was applied to the patient group. The voices of the patients were evaluated by the Dr.Speech-4 and Spectra-PRO computer programs. Maximum phonation time, fundamental frequency, amplitude and the harmonic-to-noise ratio were recorded and compared with those of the control group. The abnormal videolaryngostroboscopic findings were more frequent in the PD group (70% versus 45%; P<0.05). Voice analysis showed significant differences in the parameters such as maximum phonation time, maximum fundamental frequency, the frequency range and the harmonic-to-noise ratio. We thought that these methods and parameters yielded sufficient information for diagnosis and follow-up of vocal function in patients with PD.

Assessment of the effectiveness of postmenopausal tibolone therapy on neural functions by measuring visual evoked potentials: a placebo-controlled study

OBJECTIVE

To assess the effect of hormone replacement therapy on neural transmission in postmenopausal women using tibolone by a non-invasive, objective way.

STUDY DESIGN

In a randomised, 3 cycle, placebo-controlled study, neurovisual transmission in optic pathways were evaluated by measuring visual evoked potentials (VEP). After neuroophtalmologic examination, eligible subjects were randomised into two groups. Treatment group (n=38) were given tibolone 2.5mg daily continuously for 3 months and control group (n=20) were treated with placebo. A baseline VEP measurement before the treatment and then at the end of first, second and third month were obtained by the EMG-evoked system in the Department of Neurology, University of Celal Bayar, Manisa, Turkey.

RESULTS

Data from 31 women from treatment group and 16 from control group were available for evaluation. The mean P(100) latency values, which indicate the transition time period between the optic stimuli and electrical change recorded on the occipital area by the skin electrodes, have showed a significant decrease for the study group (from 100.39+/-0.58 to 97.90+/-0.65 ms, P<0.01) at the end of the first month of treatment according to the baseline values. This difference between two groups has remained constant during the study period.

CONCLUSION

The change in latency measurements of VEP, reflecting the functional status in optic pathways from retina to occipital cortex were significantly different in the treatment group than in that of control. We concluded that a facilitating effect of tibolone was observed on neurovisual transmission.

Total intravenous anesthesia versus single breath technique and anesthesia maintenance with sevoflurane for bariatric operations

BACKGROUND

The choice of anesthetic technique for general anesthesia in morbidly obese patients remains controversial. We aimed to compare blood gases, recovery and hemodynamic parameters using TIVA and sevoflurane anesthesia in bariatric surgery.

METHODS

The study was performed with permission of the ethics committee. We studied 40 morbidly obese patients allocated to 2 groups. The total i.v. anesthesia (TIVA) group was named Group T, and the sevoflurane group was named Group S. In Group T, anesthesia induction was achieved with propofol. In Group S, anesthesia induction was achieved by sevoflurane with single breath technique, with maintenance provided with 1-2% volume sevoflurane. Student t, Chi square and ANOVA tests were used for data analysis; p-value < 0.05 was considered statistically significant.

RESULTS

There was no significant difference between the 2 groups in demographic data, blood gas values and recovery characteristic. Hemodynamic values were significantly lower in Group T than Group S, during and after the operative period.

CONCLUSION

While sevoflurane induction and maintenance is a suitable anesthetic modality for obese patients, TIVA can be applied easily in those patients possessing no extra risk factors other than morbid obesity.

Do we need new indications for ECMO in neonates pretreated with high-frequency ventilation and/or inhaled nitric oxide?

OBJECTIVE

High-frequency ventilation (HFV) and/or inhaled nitric oxide (iNO) has reduced ECMO in neonates. But, frequently, improvement with HFV/iNO is temporary and only prolongs lung injury without preventing ECMO. We tried to identify a threshold oxygenation index (OI) that predicts temporary or persistent improvement with HFV/iNO in neonatal ECMO candidates as early as possible.

DESIGN

Cohort study of all neonates with OI > 40 during intermittent positive pressure ventilation between 1992 and 1997. The first treatment was HFV; at an OI > 40 during HFV, iNO was added; at an OI > 40 during HFV+iNO, ECMO was initiated. Temporary improvement was defined as secondary need for ECMO or fatal chronic lung disease without ECMO.

SETTING

University hospital level III neonatal intensive care unit.

MAIN RESULTS

Ten of the 34 neonates studied rapidly required ECMO despite HFV/iNO. Eleven neonates temporarily improved for 1-10 days before the OI was again > 40. Nine received ECMO, two were denied ECMO after mechanical ventilation > 14 days and died of chronic lung disease. Thirteen neonates persistently improved with HFV/iNO without ECMO. The OI before, at 24 h or 48 h of HFV/iNO did not predict temporary or persistent improvement. However, after 72 h of HFV/iNO, neonates with persistent improvement had lower OIs than those with temporary improvement [median OI 16 (4-24) vs 31 (20-40); P = 0.0004]. In all neonates with an OI > or = 25 after 72 h, HFV/iNO eventually failed (positive predictive value 100%, sensitivity 91 %, specificity 100%, positive likelihood ratio 91).

CONCLUSION

For neonates pretreated with HFV/iNO, an OI > 40 is an inadequate ECMO indication. Based on our data we hypothesize that an OI > or = 25 after 72 h of HFV/ iNO is a better ECMO indication that avoids prolonged barotrauma.

Tracheal rupture during transhiatal esophagectomy and anaesthetic problems. A case report

Tracheal rupture is a rare but potentially serious complication of transhiatal esophagectomy (THE). In this situation, ventilation of the patient can be extremely difficult, even impossible, due to excessive gas leakage from tracheal tear. In this case report, we present such a patient in whom emergency thoracotomy and patching of the trachea were performed in order to maintain ventilation and oxygenation.