Monipuolinen johdatus kansainvälisen muuttoliikkeen tutkimukseen

Kirjallisuusarvostelu

Interaction of heat-moisture conditions and physical properties in oat processing: II. Flake quality

Product quality is an important determinant of consumer acceptance. Consistent oat flake properties are thus necessary in the mill as well as in the marketplace. The effects of kilning and tempering conditions (30, 60 or 90 min at 80, 95 or 110 degrees C) on flake peroxidase activity, size, thickness, strength and water absorption were therefore determined. After kilning, some peroxidase activity remained but steaming and tempering effectively destroyed the activity of these enzymes. Thus the supposed protective effect of kilning or groat durability was not confirmed. Kilning resulted in an increase in flake specific weight, but no other significant effect on flake quality was observed. Tempering time and temperature interacted significantly to produce complex effects on flake specific weight, thickness and water absorption. Flake thickness and specific weight were significantly correlated (r = 0.808, n = 54). Longer tempering times resulted in an increased fines' fraction, from 1.45% at 30 min to 1.75% at 90 min. It is concluded that whilst kilning has little effect on flake quality, the heat treatment immediately prior to flaking, can be used to adjust flake quality independently of flake thickness.

Interaction of heat-moisture conditions and physical properties in oat processing: I. Mechanical properties of steamed oat groats

Research interest in oats has focussed on their nutritional value, but there have been few studies of their food processing. Heat treatment is characteristic of oat processing, as it is needed to inactivate lipase and to facilitate flaking. A Texture Analyser was used to characterise the mechanical properties of unkilned and kilned oat groats after steaming and tempering in an oven for 30, 60 and 90 min at 80, 95 and 110 degrees C. Maximum force, number of peaks before maximum and final force after 5s hold were used to characterise the behaviour of the groats during compression. Kilned groats were larger and softer before steaming. After steaming and tempering, the moisture content of the kilned groats was higher than for unkilned groats. Hot, steamed oats were softer than cold, unsteamed groats, indicated by a decrease in maximum force from 59 to 55 N, and there was no significant difference between kilned and unkilned groats. However, higher temperatures during tempering increased maximum force. These results suggest that mild steam treatment yields softer oat groats, whereas cold or over-treated groats tend to be harder. (c) 2007 Elsevier Ltd. All rights reserved.

Influence of some processing and storage conditions on the mechanical properties of oat flakes

Flake breakage and texture are important quality, criteria in oat flakes. These properties are determined by the mechanical properties of the flakes, which may be influenced by process variables such as kilning and flake thickness. A pin deformation method was used to measure the rupture force of individual oat flakes at different water activities. The monolayer value of ground oat flakes ranged from 5.83 to 684 g/100 g dry matter Thick flakes were strongest, requiring 3.4 N to rupture the flake compared to 2.2 N for the thin flakes. Water softened the flakes, causing a decrease in rupture force from 3.6 N to 2.4 N as water activity; increased from 0.115 to 0.848. Kilning had a significant effect on flake thickness but not on the mechanical properties. This study suggests that oat flakes should be stored at water activity 0.4 or less as there is a sharp loss of flake strength above this point.

Basilar artery occlusion

The clinical presentation of basilar artery occlusion (BAO) ranges from mild transient symptoms to devastating strokes with high fatality and morbidity. Often, non-specific prodromal symptoms such as vertigo or headaches are indicative of BAO, and are followed by the hallmarks of BAO, including decreased consciousness, quadriparesis, pupillary and oculomotor abnormalities, dysarthria, and dysphagia. When clinical findings suggest an acute brainstem disorder, BAO has to be confirmed or ruled out as a matter of urgency. If BAO is recognised early and confirmed with multimodal CT or MRI, intravenous thrombolysis or endovascular treatment can be undertaken. The goal of thrombolysis is to restore blood flow in the occluded artery and salvage brain tissue; however, the best treatment approach to improve clinical outcome still needs to be ascertained.

Therapy of basilar artery occlusion: a systematic analysis comparing intra-arterial and intravenous thrombolysis

BACKGROUND AND PURPOSE: Basilar artery occlusion (BAO) is an infrequent form of acute stroke, which invariably leads to death or long-term disability if not recanalized. A traditional recanalization approach based on historical controls and pathophysiological consideration is local intra-arterial thrombolysis (IAT) in eligible patients. This necessitates diagnostic evaluation and treatment in stroke centers equipped with an interventional neuroradiological service on a 24-hour basis, but its superiority to the technically simple intravenous thrombolysis (IVT) remains unproven. METHODS: We analyzed systematically published case series of substantial size reporting the outcome of BAO after IAT or IVT. RESULTS: In 420 BAO patients treated with IVT (76) and IAT (344), death or dependency were equally common: 78% (59 of 76) and 76% (260 of 344), respectively (P=0.82). Recanalization was achieved more frequently with IAT (225 of 344; 65%) than with IVT (40 of 76; 53%; P=0.05), but survival rates after IVT (38 of 76; 50%) and IAT (154 of 344; 45%) were equal (P=0.48). A total of 24% of patients treated with IAT and 22% treated with IVT reached good outcomes (P=0.82). Without recanalization, the likelihood of good outcome was close to nil (2%). CONCLUSIONS: Recanalization occurs in more than half of BAO patients treated with IAT or IVT, and 45% to 55% of survivors regain functional independence. Although improved therapy forms for BAO are necessary, hospitals not equipped for IAT may set up IVT protocols. The effect of IVT is probably not much different from the effect of IAT. IVT represents probably the best treatment that can be offered to victims of acute BAO in such hospitals.

Treatment and outcomes of acute basilar artery occlusion in the Basilar Artery International Cooperation Study (BASICS): a prospective registry study

BACKGROUND: Treatment strategies for acute basilar artery occlusion (BAO) are based on case series and data that have been extrapolated from stroke intervention trials in other cerebrovascular territories, and information on the efficacy of different treatments in unselected patients with BAO is scarce. We therefore assessed outcomes and differences in treatment response after BAO. METHODS: The Basilar Artery International Cooperation Study (BASICS) is a prospective, observational registry of consecutive patients who presented with an acute symptomatic and radiologically confirmed BAO between November 1, 2002, and October 1, 2007. Stroke severity at time of treatment was dichotomised as severe (coma, locked-in state, or tetraplegia) or mild to moderate (any deficit that was less than severe). Outcome was assessed at 1 month. Poor outcome was defined as a modified Rankin scale score of 4 or 5, or death. Patients were divided into three groups according to the treatment they received: antithrombotic treatment only (AT), which comprised antiplatelet drugs or systemic anticoagulation; primary intravenous thrombolysis (IVT), including subsequent intra-arterial thrombolysis; or intra-arterial therapy (IAT), which comprised thrombolysis, mechanical thrombectomy, stenting, or a combination of these approaches. Risk ratios (RR) for treatment effects were adjusted for age, the severity of neurological deficits at the time of treatment, time to treatment, prodromal minor stroke, location of the occlusion, and diabetes. FINDINGS: 619 patients were entered in the registry. 27 patients were excluded from the analyses because they did not receive AT, IVT, or IAT, and all had a poor outcome. Of the 592 patients who were analysed, 183 were treated with only AT, 121 with IVT, and 288 with IAT. Overall, 402 (68%) of the analysed patients had a poor outcome. No statistically significant superiority was found for any treatment strategy. Compared with outcome after AT, patients with a mild-to-moderate deficit (n=245) had about the same risk of poor outcome after IVT (adjusted RR 0.94, 95% CI 0.60-1.45) or after IAT (adjusted RR 1.29, 0.97-1.72) but had a worse outcome after IAT compared with IVT (adjusted RR 1.49, 1.00-2.23). Compared with AT, patients with a severe deficit (n=347) had a lower risk of poor outcome after IVT (adjusted RR 0.88, 0.76-1.01) or IAT (adjusted RR 0.94, 0.86-1.02), whereas outcomes were similar after treatment with IAT or IVT (adjusted RR 1.06, 0.91-1.22). INTERPRETATION: Most patients in the BASICS registry received IAT. Our results do not support unequivocal superiority of IAT over IVT, and the efficacy of IAT versus IVT in patients with an acute BAO needs to be assessed in a randomised controlled trial. FUNDING: Department of Neurology, University Medical Center Utrecht.

Time window for recanalization in basilar artery occlusion: Speculative synthesis.

Basilar artery occlusion (BAO) is one of the most devastating forms of stroke and few patients have good outcomes without recanalization. Most centers apply recanalization therapies for BAO up to 12-24 hours after symptom onset, which is a substantially longer time window than the 4.5 hours used in anterior circulation stroke. In this speculative synthesis, we discuss recent advances in BAO treatment in order to understand why and under which circumstances longer symptom duration might not necrotize the brainstem and turn therapeutic attempts futile. We raise the possibility that distinct features of the posterior circulation, e.g., highly developed, persistent collateral arterial network, reverse filling of the distal basilar artery, and delicate plasma flow siding the clot, might sustain brittle patency of brainstem perforators in the face of stepwise growth of the thrombus. Meanwhile, the tissue clock characterizing the rapid necrosis of a typical anterior circulation penumbra will not start. During this perilous time period, recanalization at any point would salvage the brainstem from eventual necrosis caused by imminent reinforcement and further building up of the clot.

Epigenetic phenotypes distinguish microsatellite-stable and -unstable colorectal cancers

Aberrant DNA methylation is a common phenomenon in human cancer, but its patterns, causes, and consequences are poorly defined. Promoter methylation of the DNA mismatch repair gene MutL homologue (MLH1) has been implicated in the subset of colorectal cancers that shows microsatellite instability (MSI). The present analysis of four MspI/HpaII sites at the MLH1 promoter region in a series of 89 sporadic colorectal cancers revealed two main methylation patterns that closely correlated with the MSI status of the tumors. These sites were hypermethylated in tumor tissue relative to normal mucosa in most MSI(+) cases (31/51, 61%). By contrast, in the majority of MSI(−) cases (20/38, 53%) the same sites showed methylation in normal mucosa and hypomethylation in tumor tissue. Hypermethylation displayed a direct correlation with increasing age and proximal location in the bowel and was accompanied by immunohistochemically documented loss of MLH1 protein both in tumors and in normal tissue. Similar patterns of methylation were observed in the promoter region of the calcitonin gene that does not have a known functional role in tumorigenesis. We propose a model of carcinogenesis where different epigenetic phenotypes distinguish the colonic mucosa in individuals who develop MSI(+) and MSI(−) tumors. These phenotypes may underlie the different developmental pathways that are known to occur in these tumors.