Biomedical subjects
Publications and source records attributed to A Uhl.
We discuss computationally efficient techniques for confidential storage and transmission of medical image data. Two types of partial encryption techniques based on AES are proposed. The first encrypts a subset of bitplanes of plain image data whereas the second encrypts parts of the JPEG2000 bitstream. We find that encrypting between 20% and 50% of the visual data is sufficient to provide high confidentiality.
OBJECTIVE: To test the hypothesis that a prototype LED light curing unit, (LCU), a commercial LED LCU and a halogen LCU achieve similar cure depths, using two shades of a camphorquinone photoinitiated dental composite. To measure the LCUs' outputs and the frequency of the LED LCU's pulsed light, using a blue LED array as a photodetector. DESIGN: Cure depth and light output characterisation to compare the LCUs. SETTING: An in vitro laboratory study conducted in the UK. MATERIALS AND METHODS: The LCUs cured A2 and A4 composite shades. A penetrometer measured the depth of cure. Analysis was by one-way ANOVA, two-way univariate ANOVA and Fisher's LSD test with a 95% confidence interval. A power meter and spectrograph characterised the LCUs' emissions. A blue LED array measured the pulsed light frequency from an LED LCU. RESULTS: Statistically significant different LCU irradiances (119 mW/cm2 to 851 mW/cm2) and cure depths (3.90 mm SD +/- 0.08 to 6.68 mm SD +/- 0.07) were achieved. Composite shade affected cure depth. A blue LED array detected pulsed light at 12 Hz from the commercial LED LCU. CONCLUSIONS: The prototype LED LCU achieved a greater or equal depth of cure when compared with the commercial LCUs. LEDs may have a potential in dentistry for light detection as well as emission.
OBJECTIVE: Although the elimination half-life of most glucocorticoids is short, they are usually administered once daily, or even on alternate days. Our hypothesis was that this practice might compromise the immunosuppressive effect of those drugs during the second part of the administration interval. METHODS: Eight healthy male volunteers were randomly assigned to receive intravenous methylprednisolone either 32 mg in the morning, or 16 mg in the morning and 16 mg in the evening in a cross-over design. Methylprednisolone concentrations were determined in plasma by high-pressure liquid chromatography. The total number of CD3+ lymphocytes, and CD4+ and CD8+ T-cell subpopulations was measured in blood. The suppression of these cells was used as a surrogate parameter for the immunosuppressive response, and expressed as reduction of the area under the effect time curve (AUETC). Possible adverse effects on blood pressure, glucose, insulin, and endogenous cortisol levels were monitored. RESULTS: There were no significant differences in methylprednisolone half-life (2.2 +/- 0.4 h), clearance (575 +/- 113 mL/min), volume of distribution (106 +/- 22 l), concentration producing the half-maximum effect on CD4+ T-cells (1.5 +/- 0.7 ng/mL), and Hill-coefficient (1.2 +/- 0.1), after single or divided dose. However, the total 24 h effect area (AUETC) of lymphocytes, and mainly CD4+ T-cells was significantly more suppressed (P = 0.008) with the divided dosage regimen than after the single dose (8422 +/- 2163 vs. 11,545 +/- 3020 h cells/microL). The surrogate markers for adverse events were not different, except for cortisol. CONCLUSION: Within a 24-h interval, two dose fractions of methylprednisolone produce a stronger and more sustained immunosuppressive response than one single bolus dose.
Selective Image Compression (SeLIC) is a compression technique where explicitly defined regions of interest (RoI) are compressed in a lossless way whereas image regions containing unimportant information are compressed in a lossy manner. Such techniques are of great interest in telemedicine or medical imaging applications with large storage requirements. In this paper we introduce and compare techniques with different functionalities. Moreover, we investigate the impact of using wavelet transforms and JPEG as underlying lossy compression algorithm.
AIMS: To investigate the quality of heroin seized in Vienna between 1987 and 1995 and to examine whether there was a relationship between the quality of heroin and the rate of drug-related deaths. DESIGN: Reports of heroin seizure analysis and post-mortem reports of heroin-related deaths in Vienna from 1987 to 1995 were analysed. RESULTS: There were 386 seizures of heroin comprising a total weight of 25 640.12 g heroin. All the seizures were in the base form. All seizures also contained a diluent, mainly lactose. Additionally, in 95 seizures caffeine, in four seizures paracetamol and in three seizures metaqualon were detected. Of a total of 764 drug-related deaths 506 cases were classified as heroin-related deaths. In 336 cases other central nervous system-depressant drugs and/or alcohol could be detected in the blood in addition to morphine (polydrug heroin-related deaths). There was evidence of a trend towards greater polydrug involvement during the study period. The age of victims of polydrug heroin-related deaths remained unchanged over time while the age of victims of pure heroin-related deaths decreased significantly. The morphine concentration in the medulla oblongata in heroin-related deaths decreased significantly. Finally, there was no statistically significant relationship between the rate of heroin-related deaths per year and the diacetylmorphine concentration of heroin seizures in that year. CONCLUSION: The results did not substantiate the widely held belief that increases in heroin-related deaths could be explained by an increase in the quality of heroin.
Conversion of the three mapped threonine phosphorylation sites in the myosin II heavy chain tail to alanines results in a mutant (3XALA) in Dictyostelium discoideum, which displays constitutive myosin overassembly in the cytoskeleton and increased cortical tension. To assess the importance of myosin phosphorylation in cellular translocation and chemotaxis, 3XALA mutant cells have been analyzed by 2D and 3D computer-assisted methods in buffer, in a spatial gradient of cAMP, and after the rapid addition of cAMP. 3XALA cells crawling in buffer exhibit distinct abnormalities in cellular shape, the maintenance of polarity and the complexity of the pseudopod perimeter. 3XALA cells crawling in buffer also exhibit a decrease in directionality. In a spatial gradient of cAMP, the behavioral defects are accentuated. In a spatial gradient, 3XALA cells exhibit a repeating 1- to 2-min behavior cycle in which the shape of each cell changes abnormally from elongate to extremely wide with lateral, opposing pseudopods. At the end of each cycle, 3XALA cells turn 90 degrees into the left or right lateral pseudopod, resulting in a dramatic depression in chemotactic efficiency, even though 3XALA cells are chemotactically responsive to cAMP. These results demonstrate that the phosphorylation of myosin II heavy chain plays a critical role in the maintenance of cell shape and in persistent translocation in a spatial gradient of chemoattractant.
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Glial progenitors strongly express the proenkephalin (PEnk) gene during their proliferation in the subventricular zone of the neocortex. Also in primary culture, astroglial cells from rat neocortex produce PEnk mRNA. Since the basal expression sharply declines after the cultured cells reach confluence, it seems to be related to cell proliferation. In contrast, activation of protein kinases A and C strongly enhances the levels of PEnk mRNA in confluent cultures. Therefore, it was investigated in cultured neocortical astroglial cells, whether the basal and stimulated expression of the PEnk gene occurred during different phases of the cell cycle. Activation of protein kinases A and C with 8Br.cAMP and tetradecanoylphorbolacetate, respectively, enhanced the PEnk gene expression only during the G1 phase. Unstimulated astroglial cells contained PEnk mRNA during the G1 as well as the S phase of the cell cycle. Since confluent astroglial cells are arrested in the G1 phase, they should have a basal expression of the gene which is comparable to that in preconfluent cells. Thus, the reduced basal expression after confluence indicates that other mechanisms may play a role, such as humoral factors or contact inhibition.
In primary culture, type I astroglial cells from neocortex of newborn rats express the proenkephalin gene. The glial cells are not homogeneous but differ in their morphology; i.e., polygonal and process-bearing cells are found. Transcription of the proenkephalin gene is increased via protein kinase A upon stimulation with cyclic AMP (cAMP) analogues. In the present study, how noradrenaline affected the expression of the proenkephalin gene in both cell types was investigated. Noradrenaline enhanced the levels of proenkephalin mRNA in a concentration-dependent manner. Experiments with subtype-selective antagonists suggested that beta 1-adrenoceptors were involved. In situ hybridization showed that proenkephalin mRNA was induced only in polygonal cells. Nor-adrenaline also increased the levels of cAMP. However, concentrations of noradrenaline that produced a maximal increase in cAMP caused only submaximal elevations of proenkephalin mRNA. This discrepancy was explained by the finding that noradrenaline increased the expression of the proenkephalin gene also via alpha 1-adrenoceptors. It is concluded that beta 1- and alpha 1-adrenoceptors can act in a synergistic manner on the expression of the proenkephalin gene in astroglial cells.
In a sample of 99 male alcoholics at an alcoholics' rehabilitation clinic we recorded drinking/abstinence behavior and depression up to 1 year after discharge. Seventy-eight patients completed the inpatient therapy, and of these, 39 respondents were recorded up to the final follow-up point. Generally, the initial, markedly elevated depression scores had declined significantly by the end of the inpatient treatment. In the abstainers, the depression scores continued to fall after release and remained low throughout the entire observation period. In patients who resumed alcohol use, relapses were accompanied by immediate, sharp increases in the scores, but declined upon a return to abstinence.
In rat cortex, a meningo-cortical injury causes complex changes in the expression of the "immediate early" genes c-fos and c-jun as well as the neuropeptide gene procholecystokinin. Within 1 h, mRNA levels of c-fos and c-jun are enhanced. Three hours later they have returned to control values. Twenty-four hours after the injury, there is a second rise in the level of c-fos-mRNA, which is accompanied by an increase in procholecystokinin-mRNA. In the present study, it was investigated whether these events are causally connected. When MK-801 (1.5 mg/kg), an ion-channel blocker, was injected 7 and 19 h after the injury, i.e. after the first rise in expression of both "immediate early" genes, it prevented the later increase in procholecystokinin-mRNA. When given 30 min prior to the injury, MK-801 (4 mg/kg) prevented the increased expression of c-fos but did not affect the later rise in procholecystokinin-mRNA. In a third experiment the cortex injury was performed in a manner which did not increase procholecystokinin-mRNA in frontal cortex. Nevertheless, expression of the c-fos gene was enhanced when determined 24 h after the operation. It is concluded that the injury-induced rise in the expression of the procholecystokinin gene is not connected with the changes in c-fos-mRNA.
In rats, surgical injury of the neocortex enhances the level of procholecystokinin-mRNA in the ipsilateral cortex. This increase in procholecystokinin gene expression was significantly reduced by the blockers of catecholamine re-uptake nomifensine (4 mg/kg), cocaine (5 mg/kg) and (+)-oxaprotiline (1.5 mg/kg) given i.m. 30 min before the injury. The ganglionic blocking agent hexamethonium (3 mg/kg) prevented this effect of (+)-oxaprotiline and nomifensine. Also the alpha 1-adrenoceptor antagonists corynanthine (2 mg/kg) and prazosin (2 mg/kg) blocked this effect of (+/-)-oxaprotiline (1.5 mg/kg). It is concluded that catecholamines acting on alpha 1-adrenoceptors can reduce the increase in procholecystokinin-mRNA caused by cortex injury. The catecholamines may be released from the sympathetic nervous system.
A knife cut injuring the meninges and the upper layers of rat neocortex transiently increases the levels of preprocholecystokinin-mRNA in the whole ipsilateral cortex. 48 h after the injury, the rise in gene expression was reduced by the edema-induced increase in tissue pressure which develops after the trauma. The beta-adrenoceptor antagonists alprenolol (4 mg/kg) and propranolol (1 mg/kg), given i.m. 30 min prior to the injury, reduced the increase by 75.6 and 100%, respectively. In contrast, blockade of alpha-adrenoceptors as well as of dopamine and serotonin receptors by respective antagonists did not affect the injury-induced increase in levels of preprocholecystokinin-mRNA. These results suggest that noradrenergic neurons can contribute via stimulation of beta-adrenoceptors to the initiation of the injury-induced increase in preprocholecystokinin gene expression.
In rat neocortex, interneurons express the gene encoding cholecystokinin. After an injury to the meninges and the underlying cortex the levels of cholecystokinin mRNA are transiently enhanced in the ipsilateral hemisphere. In the present study, we have investigated, whether platelet-activating factor plays a role in this phenomenon. Two antagonists of platelet-activating receptors, i.e. WEB 2086 (1.5 mg/kg) and brotizolam (10 mg/kg), were used. When injected 30 min prior to the injury of the parietal cortex, both agents reduced the rise in the concentration of cholecystokinin mRNA in frontal cortex by approximately 60%. They had no significant effect when given 30 min after the injury. Our finding that antagonists of platelet-activating factor receptors diminish the injury-induced change in the activity of cholecystokinin-interneurons opens the possibility that these agents may also affect other pathophysiological aspects of brain trauma.
DNA polymerase alpha and DNA polymerase alpha--primase complex of Physarum polycephalum were purified by rapid methods, and antibodies were raised against the complex. In crude extracts, immune-reactive polypeptides of 220 kDa, 180 kDa, 150 kDa, 140 kDa, 110 kDa, 86 kDa, 57 kDa and 52 kDa were identified. The structural relationships between the 220 kDa, 110 kDa and 140 kDa (the most abundant form) was investigated by peptide mapping. The 140 kDa form was active DNA polymerase alpha. The 57 kDa and the 52 kDa polypeptides were identified as primase subunits by auto-catalytic labelling. In amoebae, the immune-reactive 140 kDa polypeptide was replaced by a 135 kDa active DNA polymerase alpha.
Attitudes and expectations of future parents towards the birth experience have changed thoroughly in the past years. In a prospective trial with 95 women we evaluated whether prepartal intentions for a common birth experience were actually carried out and what changes occurred during the past 5 years. 95 women with uncomplicated pregnancies filled in a questionnaire in the 38th week of pregnancy and several days after birth. Behavioural intentions and their realisation correlated well. The changes of attitude became evident comparing our results with those of a survey made 5 years ago in the same hospital. Depending on the social status of the couples, an increase in the participation of fathers of up to 30% was noted. 92% of the couples of social stratum B experienced childbirth together. Participation in any kind of birth preparation was comparably low and seems improvable. Women of lower social status, in particular, should be supported instead of discouraged to attend birth preparation courses.
Quite a number of young parents want to consciously experience and take active part in the very first days after childbirth. We interviewed prospectively 95 women as to their attitude towards rooming-in, breast-feeding and child care and how they had been able to carry out their intentions. Special consideration was given to those personal and institutional factors that might promote or reduce their feeling of satisfaction with the rooming-in experience. 89 couples made use of the rooming-in offer. 78 of them found the offered times "just right". Women wanting to go back to work used rooming-in significantly more often than housewives. 92% of the persons interviewed regretted not being allowed to change diapers or to bathe the baby. Those women who even before parturition had been wanting to bathe their infants and change diapers, returned their baby to the nurses significantly less often. Thus, both institutional and interactional problems contribute towards the successful management of the postnatal period. Women whose partners attended rooming-in, and those who retrospectively agreed with their decision of how to give birth, were significantly more satisfied with their overall experience.
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