Biomedical subjects
Publications and source records attributed to J Kraemer.
The purpose of this paper is to present the status of that part of the [Microgravity Application Program] project related to the study of cartilage formation from pig chondrocytes. The work carried out so far followed two lines: (i) chondrocytes were incubated for up to three weeks in the RPM; (ii) a module developed for in-vitro cartilage formation will be tested in a sounding rocket flight (MASER 9, November 2001).
BACKGROUND: Dysthymic disorder is characterised as a chronic state of depressed mood which is not otherwise attributable to physical, psychological or social events. While it can occur alone, there is increasing evidence that the majority of individuals who meet criteria for dysthymic disorder also experience more severe episodic mood disorders throughout their lifetime, and there is also an aggregation of mood disorders within their family members. Patients with dysthymic disorder are most often seen in primary care. Some researchers suggest that the majority of these individuals are never diagnosed or are not diagnosed until a more severe episodic mood disorder develops. The objective of this study was to determine the 12-month prevalence of Axis I psychiatric disorders, and in particular dysthymic disorder, in a primary care Health Service Organization in Ontario, Canada. METHODS: Eligible and consenting adults registered with a primary care Health Service Organization were screened using the modified form of the University of Michigan Composite International Diagnostic Interview. RESULTS: Of the 6280 eligible subjects, 4327 (69%) consented to screening. Two hundred and twenty-two (5.1%) subjects screened positive for dysthymic disorder. In addition, 90% of those who screened positive for dysthymic disorder also screened positive for other Axis I disorders including major depressive disorder, panic, simple phobia, and generalized anxiety disorder. CONCLUSIONS: There is much potential for the primary care physician to play a pivotal role in the recognition and treatment of dysthymic disorder and associated Axis I disorders. A focus on the family as a unit for care may be especially important given the reported aggregation of dysthymic disorder within families.
The critical role of microtubules in vectorial delivery of post-Golgi carrier vesicles to the apical cell surface has been established for various polarized epithelial cell types. In the present study we used secretory granules of the rat and chicken pancreas, termed zymogen granules, as model system for apically bound post-Golgi carrier vesicles that underlie the regulated exocytotic pathway. We found that targeting of zymogen granules to the apical cell surface requires an intact microtubule system which contains its colchicine-resistant organizing center and, thus, the microtubular minus ends close to the apical membrane domain. Purified zymogen granules and their membranes were found to be associated with cytoplasmic dynein intermediate and heavy chain and to contain the major components of the dynein activator complex, dynactin, i.e. p150Glued, p62, p50, Arp1, and beta-actin. Kinesin heavy chain and the kinesin receptor, 160 kD kinectin, were not detected as components of zymogen granules. Immunofluorescence staining showed a zymogen granule-like distribution for dynein and dynactin (p150Glued, p62, p50, Arpl) in the apical cytoplasm, whereas kinesin and kinectin were largely concentrated in the basal half of the cells in a pattern similar to the distribution of calreticulin, a component of the endoplasmic reticulum. Secretory granules of non-polarized chromaffin cells of the bovine adrenal medulla, that are assumed to underlie microtubular plus end targeting from the Golgi apparatus to the cell periphery, were not found to be associated with dynein or dynactin. To our knowledge, this is the first demonstration of major components of the dynein-dynactin complex associated with the membrane of a biochemically and functionally well-defined organelle which is considered to underlie a vectorial minus end-driven microtubular transport critically involved in precise delivery of digestive enzymes to the apically located acinar lumen.
Sampling of batches studied for validation is reported. A thief particularly suited for granules, rather than cohesive powders, was used in the study. It is shown, as has been demonstrated in the past, that traditional 1x to 3x thief sampling of a blend is biased, and that the bias decreases as the sample size increases. It is shown that taking 50 samples of tablets after blending and testing this subpopulation for normality is a discriminating manner of testing for homogeneity. As a criterion, it is better than sampling at mixer or drum stage would be even if an unbiased sampling device were available.
The membrane surface of polarized epithelial cells can be separated in apical and basolateral domains that differ in molecular composition and function. Components of the cytoskeleton obviously play an important role in both generation and maintenance of epithelial polarity. The microtubular system is uniformly aligned in enterocytes and pancreatic acinar cells with the minus ends of the microtubules located apically and the plus ends basally. Drug-induced disassembly of microtubules results in mistargeting of pancreatic zymogen granules and of apical but not basolateral membrane proteins of enterocytes. Association of zymogen granules with the minus end motor protein, cytoplasmic dynein, and components of its receptor, dynactin, indicates that microtubules are important for vectorial delivery of apical but not basolateral post-Golgi vesicles. The lateral membrane domain of the gut epithelium is scaffolded by a spectrin-based membrane cytoskeleton consisting basically of actin, spectrin, and ankyrin. Ankyrin binds to different integral membrane proteins, such as the sodium pump in glandular and kidney epithelial cells or to the anion exchanger (AE2) of gastric parietal cells, thereby probably playing a critical role in maintenance and/or generation of the polarized distribution of these basolateral membrane proteins. Scattered epithelial cells sharing apical cytoskeletal features of gustatory receptor cells were identified as brush cells (tufted cells). These cells are rich in nitric oxide synthase and contain in their apical brush border the gustatory trimeric G-protein, alpha-gustducin, indicating that brush cells are involved in chemoreceptive signaling.
Two controlled studies for a new epidural, perineural, single-shot, selective nerve root injection with a double-needle approach to the anterior epidural space of the lumbar spinal canal are presented. The results were analysed to determine the effectiveness of the new epidural perineural injection technique. The trial comprised two controlled studies on 182 patients. One study compared prospectively randomized results of patients with lumbar radicular syndromes who received epidural perineural injections (n = 47), conventional posterior epidural injections (n = 40) and, as a control group, paravertebral local anaesthetic (n = 46). A second, prospective, double-blind study compared the effect of epidural perineural injections with triamcinolone (n = 24) and pure saline (n = 25). Epidural perineural injections were more effective than conventional posterior epidural injections. Both epidural groups had better results than the paravertebral local injection group. Epidural perineural injections with steroids (10 mg triamcinolone) were more effective than saline alone. A systemic steroid effect was excluded by additional intramuscular steroid injections in the saline group. There were no severe complications or side effects in any of the three groups. The studies concluded that single-shot epidural perineural injection is effective in the treatment of lumbar radicular pain. It is a "one drop only" therapy to the source of pain.
The disc is an osmotic system that lives from motion. Because of the human sedentary nonmoving lifestyle, disc degeneration is progressive. The morbidity curve does not follow the degeneration curve. In patients between 40 and 50 years old, discs have highlights in their clinical course because of the biomechanical constellation, with the presence of tears and fissures in the anulus and maintained expansion power of nucleus material. In old discs, the nucleus is not willing to move. This is the comfortable rigidity of the aging spine. Not only during lifetime also in case of acute back pain and sciatica natural course is benign. If patients and their doctors wait long enough, most pain curves drop, so that initially planned surgery can be cancelled. This is the waiting list phenomenon. Few patients need a disc operation because of hard disc fragments, which can be identified on magnetic resonance imaging. Open disc surgery is the most frequent and important spine operation. Proper patient selection and good technique with a small approach by microsurgery can help avoid PDS, the worst course and prognosis of intervertebral disc disease.
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The human intervertebral disc acts as an osmotic system. Water, salt, and other low-molecular substances penetrate the cartilage plates and annulus fibrosus. The content of water, sodium, potassium, and ashes in different regions of 69 human lumbar intervertebral discs was examined before and after being loaded with certain weights. Under load, the disc loses water (annulus 11%, nucleus 8%) and gains sodium and potassium. The higher concentration of electrolytes in the disc after a long period of loading increases its osmotic absorption force and enables the disc to hold back the remaining water, even against a considerable pressure. After reduction of the pressure, water is quickly reabsorbed and the disc gains height and volume. The pumping mechanism maintains the nutrition and biomechanical function of the intervertebral disc.