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PubMed2002

Progressive changes in neurofilament proteins and growth-associated protein-43 immunoreactivities at the site of cervical spinal cord compression in spinal hyperostotic mice.

STUDY DESIGN: Immunohistochemical examination of the expression and localization of neurofilament (NF) proteins and growth-associated protein (GAP)-43 in spinal hyperostotic (twy/twy) mice with progressive compression of the cervical spinal cord. OBJECTIVE: To determine the biologic functions of NF proteins and GAP-43 in the mouse cervical spinal cord during chronic mechanical compression. SUMMARY OF BACKGROUND DATA: The pathologic and repair process in the chronically compressed spinal cord are understood poorly. The present authors hypothesized that there existed an increased expression of NF proteins and GAP-43 in twy/twy mice during the lengthy period of spinal cord compression, which resembles compressive myelopathy. METHODS: The cervical spinal cords of 54 twy mice (aged 8 weeks [n = 18], 14 weeks [n = 18], and 20 weeks [n = 18]) and 18 control animals were examined histologically. Using appropriate antibodies, sections were also stained immunohistochemically for NF proteins and GAP-43. RESULTS: Separation of the myelin sheath from the axon and axonal swelling with deformation were detected in the anterior and lateral funiculi of the spinalcords of 20-week-old twy/twy mice. No such changes were noted in 8-week-old twy mice. In twy/twy mice aged 8 and 14 weeks with mild-to-moderate compression, weak immunoreactivities (mainly in the white matter) for NF proteins and GAP-43 were noted; however, in 20-week-old twy/twy mice, these axons stained strongly positive and immunoreactive swollen axons were present. The relative area of GAP-43 immunoreactive axons gradually increased between 8 and 20 weeks in each column, particularly in the anterior and lateral funiculi in the contralateral side of compression. CONCLUSIONS: The results showed that the expression of NF proteins and GAP-43 in the white matter increased proportionally with the magnitude of spinal cord compression, and indicated the possible involvement of GAP-43 in both axonal degeneration and repair processes in the chronically compressed spinal cord.

Aging↗

PubMed2004

The effect of static torsion on the compressive strength of the spine: an in vitro analysis using a porcine spine model.

STUDY DESIGN: Matched porcine cervical spine motion segments were subjected to two main conditions and compared: axial compression and axial compression combined with varying axial torque. OBJECTIVES: To determine the effect of torsion on the acute compressive strength of the spine. SUMMARY OF BACKGROUND DATA: The spine is often subjected to compression together with axial torque as a component of complex loading, yet there is a lack of documentation on its effect on the compressive strength and injury mechanics. METHODS: Matched cohorts of porcine cervical spine (C5-C6) motion segments were compressed to failure at a rate of 3,000 N/s combined with 0 Nm, 5 Nm, 20 Nm, or 30 Nm of axial torque. Three "failure" points were recorded from the stress/strain association: the first "step" (initial microfracture), the initial slope change (yield point or "slow crush" mechanism), and the ultimate failure point (fracture). Furthermore, resultant injuries were documented using planar radiography and visual inspection following dissection of the motion segments. RESULTS: Axial torque affected the failure characteristics during acute compressive loading. The ultimate strength of the motion segments was significantly reduced with increasing static torques. The compressive load at which initial microfracture occurred, indicated by the first "step" in the load-deformation curve, was increased with 5 Nm, 10 Nm, and 20 Nm of applied torsion in comparison to no torque, but this effect was reduced with 30 Nm of torque. The "slow crush" mechanism of failure was not affected by the addition of axial torque. No radiographic gross injuries to the facet joints were observed. Damage appeared to be confined to the endplate and trabecular network of the vertebral body. CONCLUSIONS: Based on this animal model, shown to have similar biomechanical behavior to humans, axial torque appears to significantly reduce the compressive strength of the spine.

Animals↗

PubMed2005

Effect of mechanical compression on the lumbar nerve root: localization and changes of intraradicular inflammatory cytokines, nitric oxide, and cyclooxygenase.

STUDY DESIGN: Investigation of intraradicular inflammation induced by mechanical compression. OBJECTIVE: To investigate the mechanism of nerve root pain, this study used a lumbar nerve root compression model. SUMMARY OF BACKGROUND DATA: The manifestation of pain at sites of inflammation has a close relationship with the release of mediators from macrophages. However, the mediators involved in inflammation of nerve roots as a result of mechanical compression remain almost unknown. METHODS: In this study, the seventh lumbar nerve root of dogs was compressed with a clip for 3 weeks to observe the changes caused by compression. Immunohistochemistry was performed using the avidin-biotin-peroxidase complex method to observe the changes of T cells (CD45) and macrophages (Mac-1) after compression. Antibodies against as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), inducible nitric oxide synthase (i-NOS), and cyclooxygenase (COX)-1 and 2 were used to examine the localization and changes of these mediators caused by nerve root compression. RESULTS: In control animals, resident T cells were detected, but there were no macrophages. IL-1beta and COX-2 were positive in the Schwann cells and vascular endothelial cells, while COX-1 was detected in the vascular endothelial cells. However, no cells showed TNF-alpha or i-NOS positively. After nerve root compression, numerous T cells and macrophages appeared among the demyelinized nerve fibers. The macrophages were positive for IL-1beta, TNF-alpha, i-NOS, and COX-2. CONCLUSION: Inflammatory cytokines, NO, and COX-2 may be deeply involved in radiculitis caused by mechanical compression, and these mediators seem to be important in the manifestation of root pain.

Animals↗

PubMed2006

An effective and efficient compression algorithm for ECG signals with irregular periods.

This paper presents an effective and efficient preprocessing algorithm for two-dimensional (2-D) electrocardiogram (ECG) compression to better compress irregular ECG signals by exploiting their inter- and intra-beat correlations. To better reveal the correlation structure, we first convert the ECG signal into a proper 2-D representation, or image. This involves a few steps including QRS detection and alignment, period sorting, and length equalization. The resulting 2-D ECG representation is then ready to be compressed by an appropriate image compression algorithm. We choose the state-of-the-art JPEG2000 for its high efficiency and flexibility. In this way, the proposed algorithm is shown to outperform some existing arts in the literature by simultaneously achieving high compression ratio (CR), low percent root mean squared difference (PRD), low maximum error (MaxErr), and low standard derivation of errors (StdErr). In particular, because the proposed period sorting method rearranges the detected heartbeats into a smoother image that is easier to compress, this algorithm is insensitive to irregular ECG periods. Thus either the irregular ECG signals or the QRS false-detection cases can be better compressed. This is a significant improvement over existing 2-D ECG compression methods. Moreover, this algorithm is not tied exclusively to JPEG2000. It can also be combined with other 2-D preprocessing methods or appropriate codecs to enhance the compression performance in irregular ECG cases.

Algorithms↗

PubMed1996

Stretch-sensitive afferent neurons in cat knee joint capsule: sensitivity to axial and compression stresses and strains.

1. Experiments were performed to determine whether the response of stretch-sensitive mechanoreceptors to tissue deformation is caused by the axial stretching of the tissue or by the associated transverse compression of the tissue caused by the Poisson effect. 2. Single, stretch-sensitive mechanoreceptors were recorded in vitro in a preparation of innervated, isolated capsule from the cat knee. Afferents were isolated in a ligamentous capsule thickening that has a uniform geometry and parallel collagen fibers. The tissue was loaded axially while simultaneously stretching it around the surface of a cylinder to produce compression stresses and strains. Axial stresses and strains were measured or estimated. 3. By altering the diameter of the cylinder, given axial stresses and strains produced different levels of compression stresses and strains. It was possible to compare the neuronal response to pure uniaxial tension with the response when both axial stretching and transverse compression was applied. 4. In 8 of 11 experiments, transverse compression did not significantly change the response (P > 0.05). In one experiment, the response was decreased by compression. In the other two experiments, the response was increased but was not a function of the magnitude of the compressive stress. 5. Compressive strain was not significantly correlated with neuron response in any experiment. 6. The data do not sustain the model that the responses of stretch-sensitive neurons are due to local compression of the afferent ending.

Animals↗

PubMed2005

Bronchial epithelial compression regulates epidermal growth factor receptor family ligand expression in an autocrine manner.

The epidermal growth factor receptor (EGFR), an important signaling pathway in airway biology, is stimulated by compressive stress applied to human airway epithelial cells. Although the EGFR ligand, heparin-binding epidermal growth factor-like growth factor (HB-EGF), is known to be released as a result of this stimulation, whether compressive stress enhances expression of other EGFR ligands, and the duration of mechanical compression required to initiate this response, is not known. Human airway epithelial cells were exposed to compressive stress, and expression of four EGFR ligands was examined by quantitative PCR. Cells were exposed to: (1) continuous compressive stress over 8 h, (2) compression with and without EGFR inhibitor (AG1478), or (3) time-limited compression (3.75, 7.5, 15, 30, and 60 min). Compressive stress produced a sustained upregulation of the EGFR ligands HB-EGF, epiregulin, and amphiregulin, but not transforming growth factor-alpha. Inhibition with AG1478 demonstrated that expression of HB-EGF, epiregulin, and amphiregulin is dependent on the signaling via the EGFR. Immunostaining for epiregulin protein demonstrated increased expression with compression and attenuation with EGFR inhibition. The response of all three EGFR ligands persisted long after the mechanical stimulus was removed. Taken together, these data suggest the possibility of a mechanically activated EGFR autocrine feedback loop involving selected EGFR ligands.

Amphiregulin↗

PubMed2006

Prediction of granule physical property by a novel compression energy of wet powder.

Wet granulation is a very important process and a reliable evaluation method for formulation study; thus it requires appropriate process control. In this study, a novel and effective method that involves a compression test of wet powder is proposed. Here, the compression energy, which could predict the capability of the wet powder for extrusion granulation as well as the physical properties of the final products, is used as a novel characteristic of wet powder. The compression energy was defined as the energy consumption derived from the compression speed and the transmission loss during the compression test. Lactose monohydrate was mixed with various additives such as hydroxypropylcellulose in the mass ratio of 0-10%. Various amounts of water were fed into the mixtures, which were kneaded in a planetary motion mixer to prepare the kneaded wet powders. The characteristics of these powders were evaluated by the compression energy. The kneaded wet powders were then extruded through an extrusion granulator, the electrical loads of the granulator during the operation were analyzed as the extrusion energy, and the physical properties of extruded granules were investigated. As a result, the granule strength and granule size distribution showed a good correlation with the compression energy. A good correlation was also observed between the compression energy of the kneaded wet powder and the extrusion energy regardless of the different additives and water contents. It was concluded that the compression energy of the wet powder could be used for the formulation study and the process control of wet granulation.

Chemical Phenomena↗

PubMed2003

Lumbar root compression in the lateral recess: MR imaging, conventional myelography, and CT myelography comparison with surgical confirmation.

BACKGROUND AND PURPOSE: Previous authors have shown that conventional myelography is superior to plain CT in the assessment of root compression in the lateral recess, but this question has never been evaluated with respect to MR imaging of the lumbar level. Our purpose was to assess the accuracy of MR imaging, conventional myelography, and postmyelography CT (CT myelography) of the lumbar level in identifying degenerative lateral recess root compression with surgical confirmation. METHODS: MR imaging, conventional myelography, and CT myelography of the lumbar level were assessed in the imaging of 58 lateral recesses at 38 lumbar levels in 26 patients who underwent surgery for radiculopathy with degenerative lateral recess abnormality. Each lateral recess was graded as normal, small without root compression, small with root compression, or severe root compression. RESULTS: MR imaging underestimated root compression in 28% to 29% of the cases in which root impingement was surgically confirmed. Conventional myelography underestimated root compression in only 5% to 7% of the cases and correctly predicted impingement in 93% to 95%. CT myelography underestimated root compression in 38% of the surgically confirmed cases. CONCLUSION: MR imaging significantly underestimated root compression caused by degenerative changes in the lateral recess. Although MR imaging is a superb study when used in the search for degenerative disk disease and disk protrusion, conventional myelography is a crucial supplemental study that is necessary to confirm degenerative root impingement in the lateral recess as the cause of radiculopathy.

Adult↗

PubMed1990

[Neurologic complications of osteoporotic vertebral compression. 3 new cases and critical analysis of the literature].

Three new cases of neurological complication by osteoporotic compression are reported. They are: a medullar compression by compression of D12 in a 66 year old woman, a deficient cruralgia by compression of L1 in a 67 year old man, and another deficient cruralgia due to the compression of L3 and L4 in a 55 year old woman. The literature presents 16 cases of neurological compressions by vertebral compressions attributed to the osteoporosis: two in 1958, and the others as from 1987. The only recently recognized feature of these complications can be explained by the axiom according to which "there are no neurological complications in the course of osteoporotic compressions" and by the introduction of new diagnosis techniques. However, the critical analysis of the published cases enables us to retain only 11 indisputable cases which, with our three observations, allows us to define certain features: the osteoporosis does not have any particularity compared to the uncomplicated form; the dorsolumbar junction is preferentially affected; the neurological complication occurs progressively and belatedly; the usual mechanism is the recoil of one of posterior vertebral corners, different from the globally convex bulging of tumoral compressions: it could be an element of the differential diagnosis. The surgical treatment gives better results.

Aged↗

PubMed1996

Multiple compression neuropathies and the double-crush syndrome.

Multiple compressions along a nerve have a cumulative effect on condition, both antegrade and retrograde. This nerve compromise renders the nerve more susceptible to a second source of compression. The proximal source of compression may be subclinical yet partially responsible for the cumulative compression syndrome. The primary "crush" may be anatomic or metabolic in origin. Strict attention to the patient's history and physical findings permit separation of the multiple compressions, making the choice of surgical decompression easier. Provocative testing and work simulation are important in examination, as is EMG testing. Complete medical evaluation can aid in diagnosing patients presenting with peripheral nerve compression and additional risk factors. Surgical decompression of a nerve with multiple levels of compression may not relieve all symptoms. Dynamic compressions in the work place and other nonsurgical types of compression must be identified so the prognosis for complete recovery is improved.

Adult↗

PubMed2001

Intermittent pneumatic compression for treating venous leg ulcers.

BACKGROUND: Intermittent pneumatic compression (IPC) is a mechanical method of delivering compression to swollen limbs. This technique has been used to treat venous leg ulcers and limb swelling due to lymphoedema. The effectiveness of IPC, and the appropriate duration and frequency of IPC therapy are unknown as are the differences between various types of IPC. This review analyses the evidence for the effectiveness of IPC as a treatment for venous leg ulcers. OBJECTIVES: To determine whether IPC increases the healing of venous leg ulcers. To determine the effects of IPC on health related quality of life of venous leg ulcer patients. SEARCH STRATEGY: The Cochrane Wound Group Trials Register was searched for RCTs of intermittent pneumatic compression in February 2001. Journals and relevant conference proceedings were searched by hand. Companies were also contacted for relevant unpublished data or ongoing studies. SELECTION CRITERIA: Randomised controlled studies either comparing IPC with control (sham IPC or no IPC) or comparisons between IPC treatment regimens, in venous ulcer management were included. DATA COLLECTION AND ANALYSIS: Data extraction and assessment of study quality were undertaken by two reviewers independently. MAIN RESULTS: Four randomised controlled trials were identified. One small trial (45 people) found increased ulcer healing with IPC plus compression than with compression alone (relative risk for healing 11.4, 95% Confidence Interval 1.6 to 82). Two small trials with a total of 75 people found no evidence of a benefit for IPC plus compression compared with compression alone. One small trial (16 people) found no difference between IPC (without additional compression) and compression bandages alone. REVIEWER'S CONCLUSIONS: Further trials are required to determine whether IPC increases the healing of venous leg ulcers.

Air↗

PubMed2000

Penile urethral compression-release maneuver as a non-invasive screening test for diagnosing prostatic obstruction.

The purpose of this study was to evaluate the feasibility of using a penile urethral compression and quick release maneuver during urination as a potential non-invasive clinical screening tool in the evaluation of patients with voiding dysfunction and the diagnosis of prostatic obstruction. The penile compression-release maneuver was performed in adult men with symptomatic voiding dysfunction and in asymptomatic normal men by compressing the penile urethra for 2-3 seconds after the initiation of flow and quickly releasing the compression. The penile compression-release index, calculated from the resulting flow rate surge (Q(surge)) and the steady flow rate (Q(surg)-Q(s)/Q(s)), was analyzed with respect to the type of voiding dysfunction. A comprehensive urodynamic study was performed in each patient to determine the presence and severity of prostatic obstruction and to measure detrusor contractility. The penile compression-release indices measured with this maneuver in patients with bladder outlet obstruction (183+/-76%, n = 43) or detrusor instability (157+/-65%, n = 13) were significantly greater than the index observed in non-obstructed patients with normal contractility (67+/-37%, n = 24) or in non-obstructed patients with impaired detrusor contractility (70+/- 32%, n = 10). In asymptomatic younger men who had normal free flow rates (>15 mL/s), the penile compression-release index (55+/-29%, n = 20) was significantly less than that observed in patients with outlet obstruction or detrusor instability. These findings suggest that the magnitude of the flow rate change generated after the penile compression-release maneuver depends on the magnitude of the isometric detrusor contraction developed during penile urethral compression and on the conduit status of the outlet. In patients determined to have poor urinary flow rates, this non-invasive maneuver has been able to differentiate prostatic obstruction associated with normal detrusor contractility from other causes of low urinary flow rates. Despite these encouraging trends, further studies in a larger cohort are required to determine its potential clinical utility as a screening tool for diagnosing prostatic obstruction.

Adult↗

PubMed1999

Down-regulation of chondrocyte aggrecan and type-II collagen gene expression correlates with increases in static compression magnitude and duration.

The goal of this study was to examine the simultaneous effects of mechanical compression of chondrocytes on mRNA expression and macromolecular synthesis of aggrecan and type-II collagen. Bovine cartilage explants were exposed to different magnitudes and durations of applied mechanical compression, and levels of aggrecan and type-IIa collagen mRNA normalized to glyceraldehyde-3-phosphate dehydrogenase were measured and quantified by Northern blot analysis. Synthesis of aggrecan and type-II collagen protein was measured by radiolabel incorporation of [35S]sulfate and [3H]proline into macromolecules. The results showed a dose-dependent decrease in mRNA levels for aggrecan and type-II collagen, with increasing compression relative to physiological cut thickness applied for 24 hours. Radiolabel incorporation into glycosaminoglycans and collagen also decreased with increasing compression in a dose-related manner similar to the changes seen in mRNA expression. The modulation of aggrecan and type-II collagen mRNA and protein synthesis were dependent on the duration of the compression. Aggrecan and type-II collagen mRNA expression increased during the initial 0.5 hours of static compression; however, 4-24 hours after compression was applied total mRNA levels had significantly decreased. The synthesis of aggrecan and collagen protein decreased more rapidly than did mRNA levels after the application of a step compression. Together, these results suggest that mechanical compression rapidly alters chondrocyte aggrecan and type-II collagen gene expression on application of load. However, our results indicate that the observed decreases in biosynthesis may not be related solely to changes in mRNA expression. The mechanisms by which mechanical forces affect different segments of the biosynthetic pathways remain to be determined.

Aggrecans↗

PubMed1993

Differential effects of compression and suction ophthalmodynamometry on the scotopic blue-flash electroretinogram.

Several studies have investigated the effect of elevated intraocular pressure with reduced ocular perfusion pressure on visual neural function by means of compression and suction ophthalmodynamometry. We compared the effects of nominally equivalent reductions in the ocular perfusion pressure induced by compression and suction ophthalmodynamometry retinal function as measured by flash electroretinography. Scotopic blue-flash electroretinograms were recorded in five subjects for baseline conditions; during a 40% reduction in the ocular perfusion pressure effected in a first test session by compression ophthalmodynamometry; and then in a second test session some 4 hours later by suction ophthalmodynamometry. Fifteen consecutive electroretinographic sets were recorded during scleral compression or suction, and also after compression or suction was removed. Compression and suction ophthalmodynamometry decreased the electroretinogram b-wave to different degrees; overall, the electroretinogram was attenuated more by compression than by suction ophthalmodynamometry. In the recovery phase, the group averaged b-wave quickly increased to exceed baseline after both scleral compression and suction. The trends for prolonged implicit times over the duration of the study were similar for compression and suction ophthalmodynamometry.

Adult↗

PubMed1993

Displaying radiologic images on personal computers: image storage and compression: Part 1.

This is the third article of our series for radiologists and imaging scientists on displaying, manipulating, and analyzing radiologic images on personal computers. Part 1 of this article discusses image storage and reviews the basic concepts of information theory and image compression; part 2 will discuss specific methods of image compression. There are a wide variety of removable storage devices available to users who need to archive radiologic images on their personal computers. Tape drives have potentially very large storage capacity but slow performance. Removable SyQuest (SyQuest Technology, Femont, CA) and Bernoulli disks have near hard disk performance and can store from 100 to 150 Mbytes. Magneto-optical drives can store nearly 1 Gb on a 5.25" disk, with somewhat slower performance. Selecting the most appropriate storage solution requires a careful balance of the user's requirements, including performance, storage needs, cost and compatibility with other users. Despite the advances in low cost high capacity storage technology, image compression remains a crucial technology for modern diagnostic radiology because digital images require such large amounts of storage. Image compression is possible because radiologic images have relatively low entropy (high information content) compared with random noise. Image compression is classified as lossless (nondestructive) or lossy (destructive). Lossless image compression commonly achieve compression ratios of 1.5:1 to 3:1 (33% to 67%), whereas lossy compression can compresses images from 3:1 to 30:1 (67% to 97%).(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Storage Devices↗

PubMed1997

Evaluation of irreversible compression of digitized posterior-anterior chest radiographs.

The purpose of this article is to assess lossy image compression of digitized chest radiographs using radiologist assessment of anatomic structures and numerical measurements of image accuracy. Forty posterior-anterior (PA) chest radiographs were digitized and compressed using an irreversible wavelet technique at 10, 20, 40, and 80:1. These were presented in a blinded fashion with an uncompressed image for A-B comparison of 11 anatomic structures as well as overall quality assessments. Mean error, root-mean square (RMS) error, maximum pixel error, and number of pixels within 1% of original value were also computed for compression ratios from ratios from 5:1 to 80:1. We found that at low compression (10:1) there was a slight preference for compressed images. There was no significant difference at 20:1 and 40:1. There was a slight preference on some structures for the original compared with 80:1 compressed images. Numerical measures showed high image faithfulness, both in terms of number of pixels that were within 1% of their original value, and by the average error for all pixels. Our findings suggest that lossy compression at 40:1 or more can be used without perceptible loss in the representation of anatomic structures. On this finding, we will do a receiver-operator characteristic (ROC) analysis of nodule detection in lossy compressed images using 40:1 compression.

Artifacts↗

PubMed2003

[Compression therapy in chronic venous insufficiency. New test procedures and therapeutic options].

Chronic venous insufficiency (CVI) has a significant socioeconomic impact. The existent venous hypertension and the subsequent capillary hypertension result in trophic skin damage culminating in an ulcer. Venous ulcers affect 1-3% of the adult population. Compression therapy provides the basis for noninvasive treatment of CVI. It can be applied alone or in combination with invasive strategies. A variety of materials are available for phlebological compression therapy in the form of compression bandages and compression hosiery. Knowledge of the different qualities of the compression materials and their mode of action is important in choosing the correct means of compression with regard to clinical findings and the patient's needs. As far as possible, the compression method applied should be monitored for any loss of effectivity during regular follow-up examinations of the patients. The following article deals with this topic. A new option for compression therapy of crural ulcers is presented and the possibility for checking the effectiveness of the compression stockings during outpatient

Bandages↗

PubMed2006

Depth profiling of compression-induced disorders and polymorphic transition on tablet surfaces with grazing incidence X-ray diffraction.

PURPOSE: The importance of induced crystal disorders like crystallite size, crystal defects, and amorphicity with respect to the dissolution rate of the drug has been discussed in many cases. Thus, the characterization of these properties is of great importance in the pharmaceutical formulation development, although the exact correlation between disorders and dissolution rate is still unclear. The aim of this study was to analyze pharmaceutical tablets with grazing incidence X-ray diffraction, which enables the depth profiling of the crystallographic properties of the tablets. To study and clarify the potential of grazing incidence diffraction in the analysis of pharmaceutical materials, the effect of the compaction process on the surface of tablets was examined. METHODS: Carbamazepine, tolbutamide, and chlorpropamide tablets, compacted using different compression pressures, were studied using grazing incidence angle X-ray diffraction. The effects of compression on the crystallographic properties were investigated as a function of the distance from the tablet surface. RESULTS: The surfaces of the tolbutamide and chlorpropamide tablets were disordered due to the compression. The manifestation of the disorder was deduced to be due to amorphicity, small crystallite size, and amount of crystal defects. The changes were mainly on the surface and diminished strongly as a function of the distance from the surface of the tablet. Moreover, the changes were dependent on the compression pressure used. The changes on the surface of the carbamazepine tablets were also due to the compression but these changes were not clearly dependent on the depth nor the compression pressure. The partial phase transition took place in the chlorpropamide tablets due to the compression. The magnitude of the transition was not highest on the surface because amorphization and texturization also took place on the tablet surface during the compression. CONCLUSIONS: The present study proved that grazing incidence X-ray diffraction is a potential novel research tool to reveal crystallographic transformations taking place on the surfaces of the tablets induced, for example, by compression pressure.

Carbamazepine↗