Robust control of uncertain context-sensitive probabilistic Boolean networks.

Uncertainty is an intrinsic phenomenon in control of gene regulatory networks (GRNs). The presence of uncertainty is related to impreciseness of GRN models due to: (1) Errors caused by imperfection of measurement devices and (2) Models' inability to fully capture a complex structure of the GRN. Consequently, there is a discrepancy between actual behaviour of the GRN and what is predicted by its mathematical model. This can result in false control signals, which can drive a cell to an undesirable state. To address the problem of control under uncertainties, a risk-sensitive control paradigm is proposed. Robustness is accomplished by minimisation of the mean exponential cost as opposed to, for instance, minimisation of the mean square cost by risk-neutral controllers. The authors derive an optimal risk-sensitive controller when a GRN is modelled by a context-sensitive probabilistic Boolean network (CSPBN). By using a relation between the relative entropy and free-energy, a relative stability of the cost achieved by the risk-sensitive controller is demonstrated when the distribution of the CSPBN attractors is perturbed, as opposed to the cost of the risk-neutral controller that exhibits increase. The use of the relation between the relative entropy and free-energy to analyse the influence of a particular attractor on the robustness of the controller is studied. The efficiency of the risk-sensitive controller is tested for the CSPBN obtained from the study of malignant melanoma.

[Diffusion and perfusion magnetic resonance imaging in evaluation of primary glial brain tumors].

INTRODUCTION: Diffusion (DWI) and perfusion (PWI) imaging can give important data about physiological characteristics of tissue, which complete morphologic findings from conventional MRI. The aim of this study is to estimate the value of these MRI technics in evaluation of primary glial brain tumors. MATERIALS AND METHODS: The significance of DWI and PWI in differentiation of histologically proven low- and high-grade gliomas was estimated in 48 patient with diagnosed brain gliomas. ADC and rCBV values were compared by aplication of Mann-Whitney test, and logistic regression analysis was used to determine which of these two parameters contributed the most in increasing the diagnostic accuracy, ia. its sensitivity, specificity and predictive velues. ROC curves were constructed to determine threshold values for differentiation of low- from high-grade lesions. RESULTS: Statistical significance were showed between mean values of rCBV for low-grade (0.82) and high-grade (5.32) gliomas, which was not found for values of ADC parameters. Threshold rCBV value of 1.23 was determinated for discrimination between low- and high-grade gliomas with a sensitivity of 83.2% and a specificity of 77.5%. CONCLUSION: Conventional MRI combined with PWI increases the accuracy in determination of glioma grade.

[Comparative evaluation of conventinal and dynamic magnetic resonance imaging, of the pituitary microadenomas].

OBJECTIVE: This study tried to determine if there is a difference between standard and dynamic MR examination in detection of pituitary microadenoma. SUBJECTS AND METHODS: We have included twenty seven patients with suspicious pituitary tumor. All patients have been hospitalized for endocrinology examination between June 2007 and May 2008 in Institute for Endocrinology, diabetes and metabolic diseases of Clinical Center of Serbia. MR examinations have been preformed in MR Center of Clinical Center of Serbia. RESULTS: Twenty seven patients were included in our study. Only in four of them pituitary microadenoma was detected using dynamic MR examination. One was somatotrophin secreting adenoma, and three were corticotrophin realizing adenomas. There were no statistically significant differences between conventional and dynamic MR examination. CONCLUSION: Dynamic MR Examination as method can hardly match standard MR examination which remains standard in detection of pituitary microadenomas.

The Belgrade dermatovenereologic moulage collection: past and present.

The Belgrade dermatovenereologic moulge collection is formed during the period between 1925 and 1958, with one break between 1940 and 1950. The first moulages have been created after the foundation of the Belgrade University's School of Medicine and the Institute of Dermatology and Venereology (IDV), when this form of education became very significant. The collection is now comprised of 350 moulages, of which 280 pieces are completely preserved, whereas 70 are previously damaged. This article describes the work of two authors of moulages: one was Dr. Sergej Pavlovic Alisov, physician, amateur sculptor and painter, and the other was academic sculptor Vojislav Sikoparija. Wide variety of presented cases of skin and venereal diseases have been analysed; before World War I, there was a high proportion and florid pathology of venereal diseases and leprosy, whereas after World War II, these diseases became infrequent. Moulages at the IDV display high authenticity, which in some cases, made possible the correction of original diagnosis according to current criteria. Moulages represent a very significant subject of medical profession, and the need of an expert opinion on the conservation and reparation of moulages, which could be implemented by those in possession of such collections, is emphasized.

Diagnosis of weaknesses in modern error correction codes: a physics approach.

One of the main obstacles to the wider use of the modern error-correction codes is that, due to the complex behavior of their decoding algorithms, no systematic method which would allow characterization of the bit-error-rate (BER) is known. This is especially true at the weak noise where many systems operate and where coding performance is difficult to estimate because of the diminishingly small number of errors. We show how the instanton method of physics allows one to solve the problem of BER analysis in the weak noise range by recasting it as a computationally tractable minimization problem.

Error correction on a tree: an instanton approach.

We introduce a method that allows analytical or semianalytical estimating of the post-error correction bit error rate (BER) when a forward-error correction is utilized for transmitting information through a noisy channel. The generic method that applies to a variety of error-correction schemes in the regimes where the BER is low is illustrated using the example of a finite-size code approximated by a treelike structure. Exploring the statistical physics formulation of the problem we find that the BER decreases with the signal-to-noise ratio nonuniformly, i.e., crossing over through a sequence of phases. The higher the signal-to-noise ratio the lower the symmetry of the phase dominating BER.

[Study of hair in type I tricho-rhino-phalangeal syndrome]. / Etude des cheveux du syndrome trichorhinophalangien type I.

Trichorhinophalangeal syndrome has three characteristic signs: slow-growing hair, pearshaped nose with high philtrum and bradyphalangia with wedge-shaped epiphyses. We report two familial cases of type I trichorhinophalangeal syndrome. Our aim was to better identify the hair anomalies. A 22-year-old boy and his 65-year-old mother had thin sparse hair with recessed fronto-temporo-occipital hair lines. The trichogramme of the occipital region showed 52% dystrophic roots and 48% telogenic roots. Polarized light revealed monochromal hair with clear << finger-end >> rhexis. Electron scan microscopy showed thin, oval, flat or cannulated hairs and folded cuticle cells. A transverse zone in the prerhexis area had no cuticle cells and << finger-end >> fractures. Histological examination showed a normal follicle count. Sebaceous and sudoriparous glands were normal. Other characteristics of trichorhinophalangeal syndrome (facial deformity with pear-shaped nose with high philtrum, clinobrachydactylia of the fingers and toes, and radiologically wedge-shaped epiphyses) were also noted. Caryotypes were normal. We emphasize the importance of folded cuticle cells and clear rhexis leading to << finger-end >> fractures. These anomalies could serve as markers in cases with few suggestive signs.

Diffuse partial woolly hair.

We report 4 new cases presenting with the characteristics of a recently described pilar dysplasia entitled 'diffuse partial woolly hair'. Two of our cases were familial (mother and daughter), while the 2 other were sporadic. Scalp hair of all the patients exhibited two hair shaft populations intermingled throughout the scalp. The first hair type was straight, normally pigmented and of normal length, while the second type was wavy and the shafts were hypopigmented, thinner, shorter and easily pluckable. One of our patients presented with a diffuse hair thinning due to a progressive loss of wavy hairs. Under reflected light, both hair populations displayed alternating dark and bright segments. Scanning-electron microscopic analysis of straight and wavy hairs revealed comparable lesions: torsions, angular kinks, weathering as well as grooved segments alternating with the normal ones. These changes were the most severely expressed in the shortest and the waviest hairs. Taken together, the clinical and microscopic characteristics of this pilar dysplasia justify its introduction as a separate entity into the woolly hair group.

[Loose anagen hair syndrome]. / Le syndrome des cheveux anagènes caducs.

In 1984, Zaun described a new type of pilary dysplasia characterized by easily pluckable hair. We were able to observe three patients with this anomaly, and this paper is an attempt at reviewing the subject on the basis of these new cases compared with those previously published. Clinical features. The major sign of the anomaly is that hairs can be pulled off in tufts easily and painlessly, and promptly grow again (our cases). In all cases reported so far the hair was blond or dark-blond; in some patients it is described as scintillating (our cases). The hair shaft is usually thin (one of our cases), but it may be of normal caliber (two of our patients). In the occipital region the hairs are entangled, dry and short (our cases). They are implanted wide apart or at normal intervals (our patients); areas of alopecia are sometimes encountered (our cases). Hair growth may be slow (one of our cases) or of normal speed (two of our cases). The eyelashes and eyebrows, as well as other body hairs, are normal in all patients (fig. 1). Microscopy. The trichogram is exclusively composed of anagenic and dystrophic roots (our cases). Pathological examination by biopsy of the scalp is characteristic: transverse and oblique sections of the follicles show that the hairs are oval, triangular or trapezoidal in shape (fig. 7). Alterations of the inner epithelial sheath are also present, including keratinization and early decomposition (fig. 8), lack of complementation (fig. 7) and fissures between the cuticle of the inner epithelial sheath and of the hair, in the keratogenic area (fig. 9). (ABSTRACT TRUNCATED AT 250 WORDS)

[Pili annulati. A scanning electron microscopy study]. / Pili annulati. Etude en microscopie électronique à balayage.

A case of ringed hair studied by light and electron microscopy is reported. The patient, a 20-year old girl, had been presenting with the hair abnormality since birth. At naked eye examination the hairs were dry, 6 to 7 cm long, and they showed dull and shining areas giving the scalp hair a scintillating appearance (fig. 1). Several samples of hair were taken and examined by light microscopy under white and polarized light. Hair shafts and cryo-fractured surfaces were examined by scanning electron microscopy. RESULTS. 1. Light microscopy. Lesions were found in every hair examined. There were abnormal, opaque and fusiform areas alternating with normal areas all along the hair shaft (fig. 2). The abnormal areas resulted from intracortical air-filled cavities. Fractures similar to those of trichorrhexis nodosa were found in the opaque areas of the distal parts of the hairs. 2. Scanning electron microscopy. A. Hair shaft surface. The abnormal areas showed a longitudinal, "curtain-like" folding of the cuticular cells which had punctiform depressions on their surface and worn free edges (fig. 4, 5, 6); trichorrhexis-type fractures were seen in the distal parts of the hair shafts (fig. 7, 8). Normal areas regularly presented with longitudinal, superficial, short and non-systematized depressions (fig. 9); the cuticular cells were worn, and there were places where the denuded cortex showed dissociated cortical fibres (fig. 10).(ABSTRACT TRUNCATED AT 250 WORDS)

[Wooly hair syndrome. Clinical and microscopic study]. / Le syndrome du cheveu laineux. Etude clinique et microscopique.

Three cases of wolly hair syndrome in the same family are reported (fig. 1; case IV-1, IV-2 and III-1). The abnormality is transmitted as a dominant autosomal trait. The main clinical features in our three patients were the fine, soft and frizzy woolly hair (fig.2) and generalized hypothrichosis. In the boy (case IV-2), atrophic follicular keratosis restricted to the cheeks developed during puberty. Serum and urinary copper and zinc levels, urinary aminoacid levels and the results of other laboratory and clinical examinations were normal. Hairs were examined by light microscopy under white light (WLM) and polarized light (PL) and by scanning electron microscopy (SEM). This study revealed the following abnormalities in most of the hair shafts: 1. The hairs were flat and appeared as oval or irregular on transverse sections (SEM; fig. 4 and 5). 2. Longitudinal and transverse grooves were present in the proximal part of the hair shaft, resulting in irregular contour of the hair. Striation of the cuticle cells was normal, with wearing of their free borders (PL, SEM; fig. 3b, 4 and 6). 3. Axial torsions were present in the proximal and distal parts of the hair. These torsions were irregular, occasional and different from true Pili torti (PL, SEM; fig. 3d and 7). 4. In the distal part of the hair the cuticle cells were either damaged or absent, with decomposition of the cortex (SEM, fig. 8), resulting in early fractures of the hairs: trichorrhexis nodosa, trichoschisis, trichoptilosis (PL; fig. 3e, f, g).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine and cholinesterase in submandibular glands of rats given armin and obidoxime.

The effects of obidoxime, a pyridinium oxime, on the cholinesterase activity and acetylcholine content of the submandibular glands of rats poisoned with armin, an organophosphorus anticholinesterase agent, were studied. The results indicate that obidoxime-induced reactivation of phosphorylated cholinesterase can suppress completely the increase in the concentration of acetylcholine that develops within the submandibular gland after administration of armin alone.