Rheological insights into 3D printing of drug products: Drug nanocrystal-poloxamer gels for semisolid extrusion

The importance of ink rheology to the outcome of 3D printing is well recognized. However, rheological properties of printing inks containing drug nanocrystals have not been widely investigated. Therefore, the objective of this study was to establish a correlation between the composition of nanocrystal printing ink, the ink rheology, and the entire printing process. Indomethacin was used as a model poorly soluble drug to produce nanosuspensions with improved solubility properties through particle size reduction. The nanosuspensions were further developed into semisolid extrusion 3D printing inks with varying nanocrystal and poloxamer 407 concentrations. Nanocrystals were found to affect the rheological properties of the printing inks both by being less self-supporting and having higher yielding resistances. During printing, nozzle blockages occurred. Nevertheless, all inks were found to be printable. Finally, the rheological properties of the inks were successfully correlated with various printing and product properties. Overall, these experiments shed new light on the rheological properties of printing inks containing nanocrystals.

Radiocarbon dioxide detection using cantilever-enhanced photoacoustic spectroscopy

In this Letter, we report on the sub-parts-per-billion-level radiocarbon dioxide detection using cantilever-enhanced photoacoustic spectroscopy. The ¹⁴C/C ratio of samples is measured by targeting a ¹⁴CO₂ absorption line with minimal interference from other CO₂ isotopes. Using a quantum cascade laser as a light source allows for a compact experimental setup. In addition, measurements of sample gases with ¹⁴CO₂ concentrations as low as 100 parts-per-trillion (ppt) are presented. The Allan deviation demonstrates a noise equivalent concentration of 30 ppt at an averaging time of 9 min. The achieved sensitivity validates this method as a suitable alternative to more complex optical detection methods for radiocarbon dioxide detection used so far, and it can be envisioned for future in situ radiocarbon detection.

Broadband Laser-Based Infrared Detector for Gas Chromatography

Cantilever-enhanced photoacoustic spectroscopy coupled with gas chromatography is used to quantitatively analyze a mixture of alcohols in a quasi-online manner. A full identification and quantification of all analytes are achieved based on their spectral fingerprints using a widely tunable continuous-wave laser as a light source. This can be done even in the case of interfering column/septum bleed or simultaneously eluted peaks. The combination of photoacoustic spectroscopy and gas chromatography offers a viable solution for compact and portable instruments in applications that require straightforward analyses with no consumables.

Cavity-enhanced cantilever-enhanced photo-acoustic spectroscopy

We have improved the sensitivity of a state-of-the-art cantilever-enhanced photo-acoustic trace gas sensor by combining it with an optical power build-up cavity. The build-up cavity enhances the photo-acoustic signal by a factor of ∼100, resulting in an exceptionally good normalised noise equivalent absorption (NNEA) value of 1.75 × 10-12 W cm-1 Hz-1/2. We demonstrate the sensor platform in the 1530 nm wavelength range with a simple distributed feedback diode laser, achieving 75 ppt sensitivity for C2H2 with a 10 s integration time.

Broadband photoacoustic spectroscopy of CH414 with a high-power mid-infrared optical frequency comb

We report a photoacoustic spectroscopy setup with a high-power mid-infrared frequency comb as the light source. The setup is used in broadband spectroscopy of radiocarbon methane. Owing to the high sensitivity of a cantilever-enhanced photoacoustic cell and the high-power light source, we can reach a detection limit below 100 ppb in a broadband measurement with a sample volume of only a few milliliters. The first infrared spectrum of CH₄14 is reported and given a preliminary assignment. The results lay a foundation for the development of optical detection systems for radiocarbon methane.

Spectroscopic thermometry for long-distance surveying

Electronic distance meters are routinely used to accurately determine the distance between two points. To reach relative measurement uncertainties of 10^-7, the average temperature along the beam has to be known within 100 mK since it is a key component in determining the refractive index of air. Temperature measurements at this level are extremely challenging over long distances and especially in an outdoor environment. This paper presents a thermometer for accurate temperature measurements over distances up to a few km. The thermometer is based on direct laser absorption spectroscopy of oxygen near 770 nm. The thermometer yields a spatially continuous measurement of air temperature, and it can provide spatially and temporally well-matching data with an actual distance-measuring laser beam. A field measurement campaign at the 864-m Nummela standard baseline demonstrates applicability of the developed thermometer for improving the refractive index compensation of current high-performance electronic distance meters.

Coping strategies, social support, life orientation and health-related quality of life following traumatic brain injury

OBJECTIVE

To study coping strategies, social support and life orientation in patients following moderate and severe traumatic brain injury (TBI) in relation to health-related quality of life.

SUBJECTS

Eighty-five patients with moderate or severe TBI and 68 control persons.

METHODS

Estonian versions of the COPE-D test, the Brief Social Support Questionnaire, the Life Orientation Test and the RAND-36 questionnaire.

RESULTS

Persons with TBI reported using task-oriented and social/emotional support strategies less often and avoidance-oriented strategies more often than control persons (p < 0.05). The social support network, satisfaction with it and optimism as life orientation were lower in the patient group (p < 0.05). Task-oriented coping styles, satisfaction with social support and optimistic life orientation were associated with the majority of the domains of health-related quality of life and resuming work after TBI.

CONCLUSIONS

To achieve effective rehabilitation and to enhance patients' well-being, it is important to improve the quality and amount of social support network, as well as to support patients' adequate coping efforts for promoting an active lifestyle.

Changes in coping strategies, social support, optimism and health-related quality of life following traumatic brain injury: A longitudinal study

PRIMARY OBJECTIVE

To study longitudinal changes in psychological coping strategies, social support, life orientation and health-related quality of life in the late period after traumatic brain injury (TBI).

SUBJECTS

Thirty-one patients with TBI who were first investigated on average 2.3 years after injury and were prospectively followed on average 5.7 years later.

METHODS

Estonian versions of the COPE-D Test, the Brief Social Support Questionnaire, the Life Orientation Test and the RAND-36 questionnaire.

RESULTS

During the late follow-up period health-related quality of life and resuming work did not improve significantly. Persons with TBI reported an increase in seeking social/emotional support (p<0.05), frequent use of avoidance-oriented styles and reduced use of task-oriented styles. This was accompanied by low social support and low satisfaction with support, both of which were associated with health-related quality of life and resuming work after TBI. Although the patients had become more optimistic (p<0.05), this did not correlate with their health status and social well-being.

CONCLUSIONS

This prospective study revealed maladaptive changes in the profile of coping strategies and an increase in optimism. As social support, satisfaction with support and health-related quality of life did not improve, then rehabilitation, social and psychological support are continuously needed.

Coping strategies in patients following subarachnoid haemorrhage

OBJECTIVES

To assess psychological coping strategies and their relationship with outcome in patients after primary subarachnoid haemorrhage (SAH).

PATIENTS AND METHODS

In 51 unselected patients (24 males, 27 females; mean age 46 years) in an average 15.7+/-12.0 months after SAH usage of coping strategies were assessed by means of Estonian COPE-D test with 15 four-items scales and compared to those obtained from 51 age-, sex- and education-matched healthy persons. The data were analysed according to age, sex and education of the patients, initial severity of disease, localization of aneurysm and outcome characteristics.

RESULTS

Patients after SAH reported using social support strategy less than control persons (P<0.05) with a tendency of using acceptance-oriented strategy. Task-oriented coping styles were less used (P<0.05) by patients with severe initial state, who had more marked late disability and dependence in daily living. Healthy women used social support more than men; patients and control persons 50 years or older used task-oriented strategies less than younger persons (P<0.05).

CONCLUSION

The structure of coping strategies used by patients after SAH differs compared to healthy persons. The differences in using coping strategies are related to age of the patients, functional state and degree of adaptation after SAH.

Neurocognitive development of children with congenital unilateral brain lesion and epilepsy

The aim of this study was to specify the neuropsychological deficits characteristic of children with unilateral non-progressive brain lesion. In order to assess these specific functions, we used a comprehensive model of congenital hemiparesis with partial epilepsy and newly diagnosed partial epilepsy without hemiparesis. The neuropsychological examination was performed using the NEPSY test battery on 44 children aged from 4 to 9 years. The children were divided into three groups: 18 children suffering from congenital hemiparesis with chronic partial epilepsy, 12 children with newly diagnosed partial epilepsy prior to anti-epileptic treatment, and 14 healthy controls matched by sex, age, and socioeconomic status. Children with congenital hemiparesis and epilepsy had a more clearly expressed cognitive dysfunction, especially in language, visuo-perceptual and memory tasks, than children with newly diagnosed partial epilepsy. The profile of cognitive weakness appears to be diffuse and quite similar in both groups, and it did not demonstrate a clear effect of lateralization, according to the side of epileptic electroencephalogram discharges. Children within both groups are likely to have a high risk of developing attention, phonological, visuo-perceptual, and memory deficits in their life. Especially interesting and surprising was the fact that the newly diagnosed epilepsy group demonstrated impairment not only in attention, visuo-perceptual and short-term memory skills, but also in auditory perception, lexical function, and the comprehension of speech. Therefore, it is recommended that children with epilepsy would undergo neuropsychological examination in order to assess their cognitive abilities.

Paradoxical facilitation of a free recall of nonwords in persons with traumatic brain injury

Brain damage is usually associated with behavioral deficits. However, there is an increasing amount of evidence that lesions of some brain regions are associated with improvements instead of impairments of certain behaviors. We report the results of a study of free recall performance in subjects with traumatic brain injury. One-fourth of the subjects displayed above-normal performance in recall of nonwords. No such facilitation was found with nine lists of words.

The possible role of CSF hydrodynamic parameters following in management of SAH patients

It is suggested that reduced intracranial compliance may be present even when measured ICP is normal and may precede clinical deterioration. Our findings reflect a decompensation of hydrodynamic parameters more pronounced 4-7 postictal days, when compliance is reduced not only in patients with poor clinical condition, but also in patients with Hunt-Hess grade I-III. Increased CSF outflow resistance in the first few days is not surprising; it is thought to be due to the blockage of flow of CSF through the basal subarachnoid cisterns and clogging of the arachnoid villi with erythrocytes and fibrin. Enlargement of ventricles seen on CT scan at the same time suggests the development of acute hydrocephalus. During the first days after SAH, our data reflects evidence of ventricular enlargement in patients presenting with both poor and better clinical condition. We conclude that the monitoring of ICP and dynamic measuring of CSF hydrodynamic parameters is important for longer than the generally accepted few days for selected cases after SAH.

Changes of sympatho-adrenal and hypothalamo-pituitary-adrenocortical system in patients with head injury

To determine the role of the sympatho-adrenal (SAS) and hypothalamo-pituitary-adrenocortical system (HPAS) after head injury, the relationship between venous blood epinephrine (E), norepinephrine (NE), adrenocorticotropic hormone (ACTH), cortisol levels, and clinical condition was examined in 55 patients. These observations suggest that head injury causes mainly activation of the above-mentioned systems depending on the severity of trauma. An inverse correlation between the levels of E, NE and Glasgow Coma Scale score, indicating the severity of head injury was revealed. ACTH and cortisol were similarly related to the clinical condition, although the observed correlation was less expressed. The changes in hormonal levels were present during the whole research period (1 week), although a certain shift to normalization was observed. However, catecholamines and ACTH levels in plasma were relatively low in severely head-injured patients whose CT scans revealed serious alterations in the mesencephalic-diencephalic area. At the same time their cortisol levels obtained maximal values and their chance to survive was diminutive. The results of this study indicate that investigation of hormones of SAS and HPAS might be useful as an additional method in the complex of ordinary examinations in establishing early prognosis in patients with brain injury.

Computerized tomography and prognosis in paediatric head injury

The authors have analysed the computerized tomography (CT) findings and their correlation with the clinical state, early and late outcome in children and adolescents with head injuries (HI). This study represents clinical and CT data of 82 consecutive HI patients under 18 years of age. Among them 51 (62%) were boys and 31 (38%) girls. The application of CT to the evaluation of the morphologic manifestations of HI in children has shown some differences in forms and mechanisms of injury and in outcome compared to adults. In the paediatric HI the most frequent finding was diffuse brain swelling with CT evidence of ventricular and cisternal compression or obliteration. Prognostically the most unfavourable findings were shearing injury, intracerebral and subdural haematomas combined with brain swelling and parenchymal damage. According to the Lidcombe impairment scale, outcome from severe paediatric HI was determined in the 3rd and 6th months, one year and 2 years after the injury. The outcome two years after severe HI varied to a great extent and was better in children than in adults. Although there was long-term disruption of the patient's quality of life, our data show that as there are no predictors of individual outcomes in child HI, no child should be excluded from early and long-term rehabilitation.

Correlations between brain oedema volume on CT and CSF dynamics in severely head injured patients

The CSF dynamics were studied in 18 patients with severe head injury who remained comatose over 6 hours after trauma (GCS less than 8). Amount of brain oedema was estimated by CT tomodensitometry. In addition, CSF parameters of PVI. Elastance (E), compliance (C) and resorption resistance (R) were calculated from serial bolus infusion tests. We observed a decrease in viscoelastic parameters as indexed by PVI, however, no increase in resistance to CSF outflow. It was noted that patients with lower PVI developed more severe brain oedema during the 3-5 day post traumatic period. From these data, we conclude that buffering capacity in severe head injury is mainly affected by the volume of brain oedema and not by the haematoma volume.