Continuous enzymatic synthesis of lactulose in packed-bed reactor with immobilized Aspergillus oryzae β-galactosidase

Lactulose synthesis from fructose and lactose in continuous packed-bed reactor operation with glyoxyl-agarose immobilized Aspergillus oryzae β-galactosidase is reported for the first time. Alternative strategies to conventional batch synthesis have been scarcely explored for lactulose synthesis. The effect of flow rate, substrates ratio and biocatalyst-inert packing material mass ratio (M_B/M_IM) were studied on reactor performance. Increase in any of these variables produced an increase in lactulose yield (Y_Lu) being higher than obtained in batch synthesis at comparable conditions. Maximum Y_Lu of 0.6 g·g^-1 was obtained at 50 °C, pH 4.5, 50% w/w total sugars, 15 mL·min^-1, fructose/lactose molar ratio of 12 and M_B/M_IM of 1/8 g·g^-1; at such conditions yield of transgalactosylated oligosaccharides (Y_TOS) was 0.16 g·g^-1, selectivity (lactulose/TOS molar ratio) was 5.4 and lactose conversion (X_Lactose) was 28%. Reactor operation with recycle had no significant effect on yield, producing only some decrease in productivity.

Synthesis of Lactulose in Continuous Stirred Tank Reactor With β-Galactosidase of Apergillus oryzae Immobilized in Monofunctional Glyoxyl Agarose Support

Lactulose synthesis from fructose and lactose in continuous stirred tank (CSTR) reactor operation with glyoxyl-agarose immobilized Aspergillus oryzae β-galactosidase is reported for the first time. The effect of operational variables: inlet concentrations of sugar substrates, temperature, feed substrate molar ratio, enzyme loading and feed flow rate was studied on reactor performance. Even though the variation of each one affected to a certain extent lactulose yield (Y_Lactulose), specific productivity (π_Lactulose) and selectivity of the reaction (lactulose/transgalactosylated oligosaccharides molar ratio) (S_Lu/TOS), the most significant effects were obtained by varying the inlet concentrations of sugar substrates and the feed substrate molar ratio. Maximum Y_Lactulose of 0.54 g⋅g^–1 was obtained at 50°C, pH 4.5, 50% w/w inlet concentrations of sugar substrates, feed flowrate of 12 mL⋅min^–1, fructose/lactose molar ratio of 8 and reactor enzyme load of 29.06 IU_H⋅mL^–1. At such conditions S_Lu/TOS was 3.7, lactose conversion (X_Lactose) was 0.39 and total transgalactosylation yield was 0.762 g⋅g^–1, meaning that 76% of the reacted lactose corresponded to transgalactosylation and 24% to hydrolysis, which is a definite advantage of this mode of operation. Even though X_Lactose in CSTR was lower than in other reported modes of operation for lactulose synthesis, transgalactosylation was more favored over hydrolysis which reduced the inhibitory effect of galactose on β-galactosidase.

Outcome of patients with primary glioblastoma in Chile: single centre series

Background

Glioblastoma (GBM) is the most common and most aggressive primary malignant brain tumour. The standard of care is surgical resection, followed by radiotherapy with concurrent and adjuvant temozolomide. In Latin America, there is scarcity of information about the incidence of GBM and even less data regarding outcomes. In this study, we describe the clinicopathologic features, management and outcomes of GBM patients.

Methods

We describe a single-centre multidisciplinary team experience in managing GBM patients over an 11-year period (Jan 2005 to Dec 2016). Pathology was reviewed by the pathology collaborator and retrospective chart review performed for treatment and clinical outcomes.

Results

We identified 74 patients (50 males) with diagnosis of GBM. Median age at diagnosis was 58 years (range 24–79 years), and median Karnofsky performance status was 80%. Forty-three (58.1%) went to gross total resection, 20 (27%) partial resection and 11 (14.9%) biopsy. Sixty-four (87%) patients received Stupp regimen. The median overall survival (OS) was 13.9 months (standard error (SE) 1.71; 95% confidence interval (CI), 10.56–17.23). In patients treated according to Stupp regimen, the progression-free survival (PFS) was 10 months (SE 1.8; 95% CI, 6.481–13.519), the selfcare survival was 11.8 months (SE 1.61; 95% CI, 8.632–14.968) and the OS was 16.1 months (SE 1.53; 95% CI, 13.01–19.099).

Conclusions

This study reports the most complete analysis of epidemiology, clinical management and outcomes of patients with diagnosis of GBM in Chile treated with Stupp regimen. The PFS and OS are consistent with reports of US and Europe.

[Deep brain stimulation in Parkinson's disease]

BACKGROUND

Deep brain stimulation is an essential therapeutic tool in Parkinson's disease.

AIM

To assess the results of a series of patients with Parkinson's disease treated with micro-electrode guided subthalamic nucleus stimulation.

MATERIAL AND METHODS

Twenty patients with idiopathic Parkinson's disease were studied (10 males). Three months after surgery, we analyzed the change in motor disturbances, medication need to control symptoms and quality of life.

RESULTS

We observed a significant improvement in all the assessed variables. Motor involvement determined as OFF hours and expressed as percentage of the day changed from 30 ± 15 to 10 ± 7% in the preoperative and postoperative periods, respectively. ON hours without dyskinesia changed from 17 ± 16 to 78 ± 21%. ON hours with dyskinesia changed from 53 ± 23 to 12 ± 15%. Medication need changed from 1,505 ± 499 to 1,214 ± 528 levodopa equivalents. Parkinson's Disease Questionnaire 39 score changed from 62.9 ± 22.7 to 34.3 ± 18.5. During the 5-year follow-up a continuous improvement of symptoms was observed.

CONCLUSIONS

Micro-electrode guided subthalamic nucleus functional surgery in patients with Parkinson's disease has good immediate and late results.

Improving use of resources-health care in patients with psychiatric pathology after introduction of risperidone long-acting injection (RLAI)

Enhance adherence to treatment is one of the main objectives in psychiatric clinical practice. The aim of this study is to evaluate changes in the use of oral antipsychotic medication, the use of rehabilitation resources and the number and duration of income in Psychiatric Inpatient Unit, comparing one year before and one year after RLAI's introduction, in patients with different psychiatric disorders, followed up by Mental Health Center and have maintained adherence to treatment for a defined period. We performed an observational, retrospective study by reviewing medical records of patients in ambulatory monitoring. The sample consisted of all patients (112) who had maintained RLAI treatment for a year, excluding those who did not fulfill the guideline correctly (14), remaining n = 98. We included patients of various pathologies, establishing groups as qualitative variables (F.20 = 56; F.25 = 12; F.22–28 = 20; F.60 = 10); of both sexes (V = 71; M = 27) and all ages. The preliminary results obtained showed a greater use of rehabilitation resources and decreased use of oral antipsychotics.