[Congenital pseudoarthrosis of the clavicle in a boy with Prader-Willi's syndrome]

The authors present the case of a boy with congenital pseudoarthrosis of the right clavicle who met all clinical and auxologic criteria of Prader-Willi's syndrome. Poor cooperation due to mental retardation was the reason for the primary conservative treatment. During this, deformity of the middle clavicle progressed, but without development of subjective complaints and functional deficit. At his 16 years, this cosmetic defect became unacceptable for his parents and, later than it is usually recommended, resection of pseudoarthrosis with plate osteosynthesis and autologous spongioplasty was indicated. The sufficient skeletal maturation and size of both fragments allowed us to perform stable osteosynthesis with the use of a contoured reconstruction plate, without the risk of insufficient osteosynthesis or clavicle fracture after the removal of osteosynthetic material.

Overexpression of amyloid precursor protein reduces epsilon protein kinase C levels

Alzheimer's disease (AD) is characterized by extracellular deposits of amyloid beta peptide (Abeta), a peptide that is generated upon proteolytic cleavage of amyloid precursor protein (APP). The events leading to the development of AD and their sequence are not yet fully understood. Protein kinase C (PKC) has been suggested to have a significant role in controlling neuronal degeneration and in the aberrant signal transduction taking place in AD. Several studies document a deficit in PKC levels and activity in brains of AD patients when compared with those of normal controls. Such a decrease in PKC could have serious implications since certain PKC isozymes were shown to drive the APP proteolytic cleavage into a non-amyloidogenic pathway. Reduced levels of distinct PKC isozymes could thus contribute to driving APP processing toward an amyloidogenic pathway. The direct cause for the down-regulation of PKC in AD brains is still unknown. In that respect, we tested in this study whether APP may play a role in PKC reduction. We show in three different cell lines (CHO, COS and BOSC) that overexpression of APP leads to decreased PKC levels. This decrease was found to be specific for the epsilon PKC isozyme whereas the levels of delta, alpha and conventional PKC remained unchanged. Furthermore, we observed this decrease for both active, membrane-associated and inactive, cytosolic epsilon PKC. APP-driven decrease in epsilon PKC is most likely mediated by a factor in the culture medium, since transfer of medium from cultured cells overexpressing APP to naïve, non-overexpressing cells, has also led to the selective decrease in epsilon PKC levels. Taken together, our results suggest that APP expression levels may play a role in the decrease of epsilon PKC levels in AD brains and could thus affect the responsiveness of AD brain tissues to growth factors and neurotransmitters.

Development of a fluorescence-based assay for screening of modulators of human organic anion transporter 1B3 (OATP1B3)

The organic anion transporting protein 1B3 (OATP1B3), formerly termed OATP8, is responsible for uptake and subsequent elimination of multiple amphipathic drugs by the liver. In silico methods for the prediction of transport rates for drugs and drug-like molecules might provide an important tool in drug development. Most prediction methods however require a large training set of in vitro experimental data in order to yield reliable results. To obtain these data, we have developed a fluorescence-based assay that allows screening a relatively high number of substances for their transporter affinity. HEK293 cells overexpressing OATP1B3 (HEK-OATP8) [Y. Cui, J. Konig, D. Keppler, Vectorial transport by double-transfected cells expressing the human uptake transporter SLC21A8 and the apical export pump ABCC2, Mol. Pharmacol. 60 (2001) 934-943.] were tested for transport of Fluo-3. Fluo-3 uptake could be seen in a concentration-dependent manner. Uptake can be inhibited completely by the addition of the known OATP1B3-inhibitor rifampicin proving that Fluo-3 is transported by OATP1B3. To verify the suitability of the system to identify modulators of OATP1B3, we tested known substrates for competitively inhibiting the Fluo-3 transport by giving them simultaneously with a 2muM Fluo-3-solution to the cells. The transport of Fluo-3 was decreased by all test substrates in a concentration dependent manner.

PET Detection of Solitary Distant Skeletal Muscle Metastasis of Esophageal Adenocarcinoma

A 67-year-old man with progressive dysphagia was recently diagnosed with a gastroesophageal junction adenocarcinoma. Contrast-enhanced CT scans of the abdomen and pelvis reported a large GE junction tumor without evidence of metastatic disease. FDG positron emission tomography revealed intense tracer accumulation in the soft tissue mass at the GE junction consistent with the primary neoplasm. In addition, PET scan also identified a solitary focus of intense FDG accumulation at the musculotendinous junction of the right gluteus minimus muscle. Subsequent MRI demonstrated mild enhancement and could not differentiate between tumor versus inflammation. Needle biopsy was performed and confirmed metastatic esophageal adenocarcinoma. A case of skeletal muscle metastases from late-stage (IV) gastroesophageal adenocarcinoma was previously reported. However, a solitary metastasis to a distant skeletal muscle without evidence of other lymphatic and hematogenous metastasis is quite unusual. The case supports the previous report that PET is superior in detecting distant metastases for initial staging of esophageal carcinoma over CT.

Subcutaneous tumor of the lower eyelid: a potential manifestation of a Dirofilaria repens infection

PURPOSE

To report a case of Dirofilaria repens presenting as a subcutaneous tumor of the lower eyelid.

METHODS

Interventional case report.

RESULTS

A 29-year-old man of Greek origin without systemic symptoms presented with a 3-week history of a small painless mass localized in the medial part of the lower eyelid. There was no history of a preceding trauma, injury, or visual impairment; however, the patient had recently been on a holiday in Italy. The lesion persisted after systemic antibiotic treatment. Routine blood tests were normal and the efferent tear ducts were patent. Upon surgical intervention a yellowish, pea-sized cyst-like structure was found beneath the orbicularis muscle and removed in toto. Histologic examination revealed the presence of a wormlike structure with the characteristic features of a single adult Dirofilaria repens nematode.

CONCLUSIONS

Infection with the nematode Dirofilaria repens has to be considered in the differential diagnosis of malignant and benign tumors of subcutaneous periocular tissues in patients who traveled to endemic areas.

[Examination of gastric emptying rate by means of 13C-octanoic acid breath test. Methods of the test for adults and results of the investigation of healthy volunteers]

BACKGROUND

13C-octanoic acid breath test (13C-OABT) is a simple, safe and non-invasive technique for measuring gastric emptying. However, the method has not been standardized yet. Aim of the study was to work up, introduce and evaluate our own method of the 13C-OABT for adults.

METHODS AND RESULTS

Ten healthy volunteers entered the study (5 men, 5 women, mean age 32 years, 50 % Helicobacter pylori positive). Standard test meals (with 100 mg 13C-sodium octanoate) were used three times within 3 weeks. The same solid meal (1,178 kJ) for Tests 1 and 2 contained scrambled egg (+ 3 g oil), white bread (40 g), butter (10 g) and distilled water (200 ml). Semi-solid meal (1,020 kJ) for Test 3 contained milk pudding (200 g) and distilled water (200 ml). Duplicate breath samples were obtained before and every 15 minutes after eating the test meal during 255 minutes. Altogether 1,080 breath samples were analysed twice (isotope ratio mass spectrometry, AP2003 Analytical Precision, UK). To assess the half-life of elimination (t1/2 E), we modelled the process of elimination with the incomplete gamma-function, which has a convenient form for the empiric plotting of breath test data. Mean t1/2E was 136+/-10 minutes (Test 1), 134+/-14 (Test 2) and 123+/-16 minutes (Test 3). Clinical reproducibility of 13C-OABT in particular persons was 98.2% (18 breath samples series), 90.8 % (15 samples) and 87.1% (9 breath samples series). There was a significant correlation between Test 1 and Test 2 results (r=0.887, p<0.0001). Mean difference of duplicate breath sample analysis was 1.460 % (in 540 pairs), mean baseline one-day analysis difference was 0.0982 (99.9274% accuracy). In healthy volunteers, normal range of t1/2E is 110-160 minutes for solids and 91-155 minutes for semisolid test meal. Using our own computed mean time of intermediate metabolism of 13C-octanoic acid (76.5+/-7.5 minutes), gastric emptying half-time is 33.5-83.5 minutes for solids and 14.5-78.5 minutes for semisolid test meal in healthy volunteers.

CONCLUSIONS

The 13C-OABT is accurate non-invasive method for gastric emptying measurement.

[Diabetes and celiac disease]

Celiac sprue is permanent lifelong intolerance of gluten which in some sensitive individuals leads to an inflammation of various grades followed by atrophy of jejunum mucosa. Diagnosis of celiac sprue is based on proof of histopathological changes in jejunum mucosa as a result of presence of gluten in food. In recent years, serum endogenous myosin and tissue transglutaminase antibodies were used in a diagnostic algorithm. We distinguish active, silent, latent, and potential celiac sprue. Simultaneous incidence of type I diabetes mellitus and celiac sprue has been documented in a range of studies. Both diseases have common immunology and genetic characters. Prevalence of celiac sprue in patients with type I diabetes is several times higher compared to prevalence of this disease in the population. There is the prevalence of celiac sprue 3.6-5.1% in children with type I diabetes mellitus in the Czech Republic, silent form of the disease is the most frequent one. An effect of a strict gluten free diet on a metabolic control of diabetes has not been proved. It is necessary to assess (at least once per two years) actively and on regular basis endogenous myosin and/or tissue transglutaminase antibodies in patients with type I diabetes.

ARX mutations in X-linked lissencephaly with abnormal genitalia

X-linked lissencephaly with abnormal genitalia (XLAG) is a distinct form of lissencephaly associated with absent corpus callosum. Recently, forms of syndromic and nonspecific X-linked mental retardation have been found to be associated with mutations in the Aristaless-related homeobox gene ARX. The authors assessed ARX as a candidate gene for XLAG in a genetic analysis of neuronal migration disorders and found two different point mutations in two XLAG pedigrees affecting the homeodomain of the protein, confirming that ARX is a causative gene for XLAG.

[Polyethylene liner dislocation in Harris Galante acetabular components]

AIM

Dislocation and subsequent dissociation of the polyethylene liner as a result of failure of the acetabular locking mechanism is a potential source of failure in the Harris-Galante acetabular component. The purposes of this study are to present seven cases with a liner dislocation due to failure of the liner locking mechanism.

METHOD

Between March 1997 and December 2001, seven patients who had had a total hip arthroplasty presented with clinical and radiologic signs of liner dislocation and signs of polyethylene wear of the liner from a Harris Galante acetabular shell. In all cases the intraoperative findings showed evidence of failure of the liner locking mechanism and subsequent dislocation. The medical records, radiographs, operative notes and explanted retrieved components were reviewed.

RESULTS

The components had been in situ for an average of 5.3 years (range 1-9 years). Two components were first generation, five were second generation. The symptoms developed spontaneously in five patients, the other two patients described a minor trauma. Radiographs showed eccentric position of the head in all cases. All acetabular components showed an excellent stability intraoperatively, nevertheless we had to remove the well fixed acetabular shell due to complete destruction of the liner locking mechanism in two cases. Treatment consisted of revision of the shell in two patients and exchange of the liner in five patients. All retrieved liners showed severe deformation and/or fracture of the rim.

CONCLUSION

Harris Galante modular acetabular components have been used widely for primary and revision arthroplasty. The survival of this implant has been well documented in the literature. Failure of the liner locking mechanism and following dislocation or fracture of the polyethylene liner is a potential cause of failure which may possibly occur more often than the literature to date has documented. We report seven cases of liner dislocation, in which two acetabular components had to be removed completely due to destruction of the liner locking mechanism. In the other five cases exchange of the liner was possible thanks to well timed revision. We believe that, as the liner wears and becomes loose due to an inefficient locking mechanism, the load increases on the polyethylene rim until it deforms or fractures. As a consequence of the prosthetic design at that stage nothing can prevent the liner from rotating out of the shell.

[Anterior intertrochanteric ossification after total hip arthroplasty]

AIM

Heterotopic paraarticular ossifications are usually identified by an anterior-posterior radiograph of the corresponding hip and are consecutively classified by the well accepted methods of Brooker, Arcq or deLee. In these methods ossifications are solely evaluated by the means of a single a-p radiograph, hence a major part of ossifications located in the anterior intertrochanteric region cannot be evaluated. Our study deals with the incidence of ossifications exclusively verifiable by an axial radiograph.

METHOD

In the present study 209 patients' axial radiographs were retrospectively analysed by using our simple method of classification. In the axial projection these ossifications are situated anterior of the intertrochanteric region, therefore we created the term "anterior intertrochanteric ossification (AIO)". After developing a simple topographic scheme we classified these appearances by localisation and size.

RESULTS

After total hip arthroplasty by using the transgluteal approach ossifications situated in the anterior intertrochanteric region can develop. These ossifications appear as bone islands, shield or clip like (without fixed connection to the femoral cortical bone) or as solid exostoses. Due to their strict anterior localisation these formations are often solely verifiable by the means of an axial (Lauenstein) radiograph. We were able to identify anterior intertrochanteric ossifications (AIO) in 97 out of 209 patients (48.4 %), 27 patients (13 %) developing an anterior intertrochanteric ossification were classified grade 0 according to the methods of Brooker, Arcq and deLee.

CONCLUSION

According to the widely accepted methods of classification of paraarticular ossifications depending on a single a-p radiograph of the corresponding hip, 13 % of paraarticular ossifications would remain undocumented because of their strict anterior intertrochanteric position.

A molecular approach to the concerted action of kinases involved in energy homoeostasis

One of the most important duties of a cell is energy homoeostasis. Several kinases, including AMP-activated protein kinase (AMPK), creatine kinase and adenylate kinase, are involved in the immediate response to stress, resulting in energy depletion. Here, we present our view of events preceding the downstream processes mediated by AMPK and leading to reduced energy expenditure and increased energy production. Unfortunately, AMPK is very poorly defined at the molecular level. Thus a procedure for production of AMPK in milligram amounts is presented which will greatly facilitate the functional and structural characterization of this protein kinase.

A novel mechanism of silicon uptake

Crystal-like structures in vacuoles, precipitates in the cytoplasm and on the tonoplast membrane have been found to store remarkable amounts of Si in a number of higher plants. In most of the cases the final storage product is a SiO(2) gel. Accumulation inside the cells presumes a membrane and cytoplasm passage, driven by unknown transporters. Beside this uptake into the cytoplasm, Si-accumulating species possess a mechanism that does not involve a membrane and cytoplasm passage. Unusual small invaginations comprising the two membranes, plasmalemma and tonoplast, which enclose a small border of cytoplasm, were observed. The same cells contained vacuolar vesicles surrounded by two membranes, obviously derived from the invaginations. By energy-dispersive X-ray analysis and electron spectroscopic imaging, Si was shown in the invaginations and vacuolar vesicles. This novel endocytotic process allows the uptake of condensed, higher-molecular-weight Si compounds. In Zn hyperaccumulators, frequently SiO(2) precipitates were found in different cell compartments. Such plants showed the same invaginations and vacuolar vesicles, but Zn, colocalized with Si, was detected in these structures. Electron energy loss spectra confirmed the assumption that Zn-silicate is present in the vesicles. In the vacuoles the unstable Zn-silicate is degraded, forming SiO(2) precipitates, while the released Zn is bound to an unknown partner.

Small-scale distribution of interstitial nitrite in freshwater sediment microcosms: the role of nitrate and oxygen availability, and sediment permeability

The spatial distribution of interstitial NO2(-) concentrations was studied in NO3(-)-exposed freshwater sediment microcosms, using pore water extractions as well as ion-selective microsensors. Porewater extractions revealed ecotoxicologically critical NO2(-) concentrations in hypoxic and anoxic sediment layers in which significant NO3(-) consumption took place. In contrast, the use of ion-selective microsensors demonstrated the high capacity of the thin oxic surface layer of the sediments to consume NO2(-) and to produce NO3(-). Two modes of NO3(-) supply to the sediments were compared: In treatments with NO3(-) supply to the overlying water, a subsurface maximum of NO2(-) concentration was observed, coinciding with the site of maximum NO3(-) consumption. When NO3(-) was perfused up through the sediment cores, however, NO2(-) accumulated throughout the entire sediment column. Such spatially extensive NO2(-) accumulations were only observed in sediments poor in organic matter with a relatively high permeability. By manipulating the O2 content of the overlying water, the release of NO2(-) from the sediments could be influenced: In treatments with air-saturated overlying water, the sediments did not release detectable amounts of NO2(-) into the water phase. When kept hypoxic (25% air saturation) instead, significant NO2(-) accumulations were recorded in the overlying water. These findings suggest that in treatments with air-saturated overlying water, NO2(-) that was produced in deeper sediment layers (denitrifying conditions) was completely consumed at the oxic sediment surface (nitrifying conditions) before it could reach the overlying water.

Interleukin-12 upregulates the IL-18Rbeta chain in BALB/c thymocytes

Interleukin-18 (IL-18) is a proinflammatory cytokine that plays an important role in innate immunity and specific Th1 immune responses. During infection, IL-18 is produced by activated macrophages and primarily induces interferon-gamma (IFN-gamma) production in synergy with IL-12 in primed T cells and natural killer (NK) cells. IL-18 exerts its function by binding to a specific receptor complex (IL-18R) consisting of two subunits, the IL-18Ralpha chain and the IL-18Rbeta chain. Two individual mechanisms for synergism between IL-12 and IL-18 have been reported. First, IL-12-induced expression of the IL-18 receptor complex was described. Second, IL-18 and IL-12 together induced expression of target genes on a transcriptional level. In this study, we show that freshly isolated thymocytes from BALB/c mice constitutively expressed mRNA for the IL-18Ralpha chain but not for the IL-18Rbeta chain. These thymocytes were unresponsive to IL-18. Treatment with a combination of concanavalinA (ConA) plus IL-12 did not affect expression of the IL-18Ralpha chain but strongly induced expression for IL-18Rbeta mRNA, rendering these thymocytes highly responsive to IL-18 treatment. Thus, the synergistic effects of IL-12 and IL-18 on BALB/c mouse thymocytes resulted from the induction and regulation of the IL-18Rbeta chain and not the IL-18Ralpha chain.