Showing papers by "University of Ioannina published in 1989"

Sharp conditions for the oscillation of delay difference equations

Abstract: Suppose that { p n } is a nonnegative sequence of real numbers and let k be a positive integer. We prove that \frac{{k^k }} {{\left( {k + 1} \right)^{k + 1} }} \]" id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"> lim n → ∞ inf [ 1 k ∑ i = n − k n − 1 p i ] > k k ( k + 1 ) k + 1 is a sufficient condition for the oscillation of all solutions of the delay difference equation A n + 1 − A n + p n A n − k = 0 , n = 0 , 1 , 2 , … . This result is sharp in that the lower bound k k / ( k + 1 ) k + 1 in the condition cannot be improved. Some results on difference inequalities and the existence of positive solutions are also presented.

A crystal molecular conformation of leucine-enkephalin related to the morphine molecule.

Abstract: Leucine-enkephalin (Try1-Gly2-Gly3-Phe4-Leu5) has been crystallized as a trihydrate from water solution. X-ray diffraction reveals a tightly folded molecular conformation with two fused beta III- (Gly2-Gly3) and beta I- (Gly3-Phe4) turns. The Tyr1 and Phe4 aromatic rings have a close orthogonal arrangement analogous to the tyramine and cyclohexenyl rings in morphine. This suggests that the conformation found in the trihydrate crystal structure could be required for recognition by mu-receptor sites.

Global attractivity in population dynamics

Abstract: We established sufficient conditions for the global attractivity of the positive equilibrium of the delay differential equation N(t)=−mu;N(t)+∑i=1m pi exp[−γN(t−τi)], t⩾0, m⩾1. For m = 1, equation (1) was used by Wazewska-Czyzewska and Lasota as a model for the survival of red-blood cells in an animal.

Evaluation of tear break-up time, Schirmer's-I test and rose bengal staining as confirmatory tests for keratoconjunctivitis sicca.

Abstract: The tear break-up time (BUT), Schirmer's I test (S-I) and slit lamp examination after rose Bengal staining (RBS) are simple tests for evaluation of keratoconjunctivitis sicca (KCS). Discrepancies, however, regarding the range of normal values and the specificity and sensitivity of these methods prompted us to reevaluate them in 81 primary Sjogren's syndrome patients (Ss) and 276 normal volunteers. In normal volunteers, BUT values ranged from 4 sec. to 32 sec. (means +/- SD: 13 +/- 6 sec.) and in primary Ss from 1 sec. to 15 sec. (means +/- SD: 7 +/- 3 sec.). Ninety five percent (95%) of the values from primary Ss patients were below 12 sec. Forty two percent (42%) of the values obtained from normal individuals fall within this range. Schirmer's I test values in normal individuals ranged from 0 mm/5 min. to 30 mm/5 min. (means +/- SD: 10 +/- 9 mm) and in primary Ss patients from 0 mm/5 min. to 30 mm/5 min. (means +/- SD: 4 +/- 7 mm.). Ninety five percent (95%) of the primary Ss patients' values were below 19 mm/5 min. Sixty eight percent (68%) of the normal individual values fall into this range. Rose Bengal staining values ranged in normals from 0 to 7 (means +/- SD: 1 +/- 1) and in primary Ss patients from 1 to 8 (means +/- SD: 5 +/- 2). Ninety five percent (95%) of the primary Ss patients' values were above 2. Only 7% of normal individual values fall into this range. From these data we conclude that rose Bengal staining is the best test for evaluation of keratoconjunctivitis sicca.

In vivo measurement of cortical bone lead using polarized x rays.

Abstract: An x‐ray fluorescence system which utilizes polarized radiation to measure lead in vivo in human subjects is described. The minimum detection limit is approximately 6.4 ppm wet weight lead in the cortex of the tibia with 4 mm of overlying soft tissue. This appears to be adequate for assessing lead stores in lead‐toxic preschool children. The measurement requires 16.5 min and is associated with an effective equivalent whole body dose to the subject of 2.5 μSv. The system, its calibration and its validation are described herein.

Neuropsychiatric abnormalities in primary Sjögren's syndrome.

Abstract: Neuropsychiatric abnormalities were searched for in 52 patients with primary Sjogren's syndrome (SS). 40 patients were evaluated with a detailed neurologic history and physical examination and determination of terminal latencies and nerve conduction velocities of all limbs. Nineteen of them, plus another 12 primary SS patients were evaluated for hostility structure and psychiatric symptoms, using the Hostility and Direction of Hostility Questionnaire (HDHQ) and the Symptoms Check List-90R (SCL-90R) respectively and the results were compared with those of 33 healthy women and 41 cancer patients. Three patients had face numbness and/or hypesthesia indicating trigeminal involvement. Ten had mild sensory or mixed neuropathy of the glove-stocking type. None of our patients volunteered peripheral nervous system (PNS) symptoms nor did we detect central nervous system (CNS) involvement in any of them. One patient with purpura, glomerulonephritis and cryoglobulinemia presented with severe mononeuritis multiplex. High levels of introverted hostility were reported by SS patients in relation to the other two groups. In addition, higher scores on paranoid ideation, somatization and obsessive compulsiveness were found in SS patients compared to the rest but no correlation was found between psychiatric symptomatology and neurologic abnormalities. It is suggested that PNS disease is relatively common and benign in most primary SS patients, psychiatric disorders, sometimes serious, are also common, but CNS involvement must be rather rare.

Sjögren's syndrome in rheumatoid arthritis and progressive systemic sclerosis. A comparative study.

Abstract: One hundred and eleven patients with rheumatoid arthritis (RA) and 44 with progressive systemic sclerosis (PSS) were prospectively evaluated for evidence of Sjogren's syndrome (Ss). The diagnosis was established when a patient with a lip biopsy focal lymphocytic infiltration score of greater than or equal to 2+ in Tarpley's scale had keratoconjunctivitis sicca (KCS) and/or xerostomia. Out of 44 RA and 10 PSS patients with positive lip biopsy, 34 and 9 had criteria for Ss respectively, suggesting a 31% prevalence of Ss in RA and a 20.5% in PSS. Six per cent of the RA patients spontaneously offered complaints of subjective xerophthalmia whereas 11.1% and 22.2% of those with PSS did so for subjective xerophthalmia and xerostomia respectively. However, specific questionnaire elicited subjective xerophthalmia in 38.2% and subjective xerostomia in 5.9% of the RA patients, whereas in 55.5% and 66.7% of the PSS ones respectively. Parotid gland enlargement was detected in 20.6% of the RA and in 44.4% of the PSS patients with Ss. Anti-Ro (SSA) antibodies were present in the sera of 23.5% and 33.3% of them respectively. Severe extraglandular manifestations were unusual in both groups. Our results suggest that, although both Ss in RA and that in PSS lack prominent exocrine gland symptomatology, certain differences between the two and similarities of the latter to primary Ss, would not justify the term 'secondary Ss' for the syndrome accompanying scleroderma, as it has been applied to that accompanying RA.

The forgotten cause of sicca complex; sarcoidosis

Abstract: Sarcoidosis is a chronic systemic disease of unknown cause with prominent symptoms from the respiratory system. It can occasionally affect the exocrine glands presenting with xerophthalmia and xerostomia similar to Sjogren's syndrome. We present 5 such patients who visited our rheumatology clinic complaining of dry eyes and mouth. Investigation for xerophthalmia and xerostomia showed positive rose bengal tests in all patients, positive Schirmer's I tests in 4 and decreased parotid flow rate in 3. Minor salivary gland biopsy showed noncaseating granulomas compatible with sarcoidosis in 3. In the other 2 patients the diagnosis was obtained with transbronchial lung biopsy that revealed noncaseating granulomas. Transbronchial lung biopsy also showed granulomas in 2 patients with positive minor salivary gland biopsy. Our results suggest that sarcoidosis can present with initial symptoms of dry eyes and dry mouth. When this happens, transbronchial and minor salivary gland biopsy are very valuable in differentiating sarcoidosis from Sjogren's syndrome.

Evaluation of unstimulated whole saliva flow rate and stimulated parotid flow as confirmatory tests for xerostomia.

Abstract: Unstimulated whole saliva collection (U.W.S.C.) and stimulated parotid flow rate (S.P.F.R.) are routine tests for evaluation of xerostomia. Different groups of investigators, however, use different normal values; some prefer one test (either one) more than the other. This prompted us to evaluate these tests in 81 well documented primary Sjogren's syndrome (prim. SS) patients and 188 age and sex matched normal volunteers. The U.W.S.C. as well as the S.P.F.R. were performed for 5 min. Lemon juice was used for stimulation and the saliva from the parotid gland was collected using modified Carlson-Crittenden cups. Normal individuals produced from between 0.20 and 6.81 ml/5 min (x +/- SD: 2.03 +/- 1.36 ml) of U.W.S. and from between 0.00 and 7.50 ml/5 min (x +/- SD: 1.00 +/- 1.10 ml) of S.P.F. No statistical differences were observed between the two salivary flow rates. Primary Sjogren's syndrome patients produced from 0.04 to 2.00 ml/5 min (x +/- SD: 0.47 +/- 0.50 ml) of U.W.S. and from 0.00 to 2.00 ml/5 min (x +/- SD: 0.37 +/- 0.56 ml) of S.P.F. Using the 95% confidence limit of the flow rates (U.W.S.: 1.25 ml/5 min and S.F.P.: 1.5 ml/5 min) observed in prim. SS patients, it was observed that 57% of the U.W.S. and 78% of the S.P.F values produced from normal individuals fall into that range. Based on these findings we conclude that these two tests are not useful for the evaluation of xerostomia.

Analysis of the long-term precipitation series at Athens, Greece

Abstract: In this paper, the characteristics of the long-term precipitation series at Athens (1858–1985) have been statistically analyzed. This study covers both the history and the analysis of the data. The ten-year mean amounts, the monthly and annual amounts averaged over the intervals 1858–1890, 1891–1985, 1951–1980, 1858–1985, the mean number of hours of precipitation and the precipitation intensity are given. The analysis of long-term time series of climatic data (in particular precipitation) is a useful tool for the study of past climate. Different statistical techniques are used in order to depict monthly, seasonal and annual variations, as well as trends, periodicities and recurrence intervals of the amount, intensity and number of precipitation days. The analysis reveals many interesting characteristics. These characteristics of the precipitation regime are extended to a time scale from seasonal variation to a semi-secular trend. The study of such long-term series may be helpful not only in practical applications of rainfall, but also for explaining the possible physical or anthropogenic mechanisms of climatic fluctuations and tendencies. The series of precipitation at Athens is one of the longest in south-eastern Europe.

Immunopathogenesis of sjogren's syndrome: “Facts and fancy”

Abstract: Sjogren's syndrome (Ss) is an ideal model to study the pathogenesis of both autoimmunity and malignancy. It occurs as an organ specific autoimmune disease, alone or in association with almost every other autoimmune disorder, as a systemic disorder, and finally it can evolve to B-cell-lymphoid malignancy. The most consistent finding in the syndrome, the B-cell-hyperreactivity, follows the same steps of evolution. It starts as polyclonal, but not random, since the autoantibody profile correlates with the disease subgroups and the systemic manifestations and it seems to be controlled by the MHC gene composition. Further, in the systemic form of the disease it presents as a poly-oligo-mono-clonal process and ends up to monoclonal (IgMk) B-lymphoid malignancy. Studies on the T-immunoregulatory subsets and function can not explain this B-cell hyperreactivity. The initial trigger is unknown. Estrogens, known as immunoenhancers possibly promote the B-cell hyperreactivity and certain genes controlling HLA class-II MHC molecules may represent susceptibility factors for the development of the disease. The discovery of lymphokines and particularly the B-cell growth and differentiation factors as well as the rapid development of the retro-virology field may give answers pertinent to the pathogenesis of Ss and to B-cell lymphoid malignancy.

Tissue distribution of inducible aldehyde dehydrogenase activity in the rat after treatment with phenobarbital or methylcholanthrene.

Abstract: Two genetically distinct substrains of the Wistar rat (RR and rr) were used to study the tissue distribution of the inducibility of aldehyde dehydrogenase (ALDH). The RR substrain is responsive to phenobarbital (PB), as far as the induction of the hepatic ALDH activity is concerned, whereas the rr substrain is deprived of this biochemical property. Both substrains, however, respond to treatment with methylcholanthrene (MC), exhibiting a uniform increase of the ALDH activity in the liver. It is known that PB and MC induce two different isozymes of the hepatic cytosol. The effect of PB (1 g/l in drinking water, for 12 days) on the inducibility of ALDH in extrahepatic tissues was examined in the RR substrain. On the contrary, MC was given (50 mg/kg x 4, intraperitoneally) to rr animals. The activity of ALDH was found to be induced by PB in the liver and the intestinal mucosa, when measured with NAD and propionaldehyde (P/NAD) or phenylacetaldehyde (Ph/NAD). An increase of the activity was also noticed when ALDH was measured with NADP and benzaldehyde (B/NADP). In rr animals, MC induced the B/NADP activity in the liver, the intestinal mucosa, the kidneys, the lungs, the spleen, the brain, the urinary bladder and the heart. The effect of MC on various tissues was less distinct, when ALDH was measured as P/NAD or Ph/NAD activity. It is concluded, that PB and MC not only induce different types of ALDH activity, but they also reveal differences in the tissue distribution of the inducibility of ALDH.

17O-NMR studies of the conformational and dynamic properties of enkephalins in aqueous and organic solutions using selectively labeled analogues.

Abstract: The synthesis of Leu-enkephalin selectively 17O-enriched in Gly2 and Gly3 is reported. The 17O-nmr chemical shifts of [17O-Gly2, Leu5]- and [17O-Gly3, Leu5]-enkephalins in H2O are almost identical and independent of the pH. Since hydrogen bonding is the dominant factor governing the chemical shifts of the peptide oxygen, it can be concluded that the hydration state of both oxygens is identical and independent of the pH. The 17O chemical shifts of the [17O-Leu5]-enkephalin terminal carboxyl group at pH approximately 1.9 and 5.6 are very different in H2O but very similar in CH3CN/DMSO (4:1) solution. This suggests that the protonation state of the carboxyl group at both pH values in CH3CN/DMSO solution is the same and consequently that Leu-enkephalin exists in the neutral form at pH approximately 5.6. In this organic mixed solvent system both Gly2 and Gly3 oxygen resonances exhibit a significant shift to high frequency by the same extent (delta delta approximately 30 ppm). It is concluded that both peptide oxygens are not hydrogen bonded to an appreciable extent and that no specific 2----5 hydrogen bonding exists to an appreciable extent. This conclusion is in agreement with the energy of activation for molecular rotation, as determined from T1 measurements, which was found to be almost identical for both [17O-Gly2, Leu5]- and [17O-Gly3, Leu5]-enkephalins in CH3CN/DMSO (4:1) mixed solvent.

Optimality relationships forp-cyclic SOR

Abstract: The optimality question for blockp-cyclic SOR iterations discussed in Young and Varga is answered under natural conditions on the spectrum of the block Jacobi matrix. In particular, it is shown that repartitioning a blockp-cyclic matrix into a blockq-cyclic form,q

Unusual eye manifestations in systemic lupus erythematosus patients.

Abstract: One hundred and twelve records of patients with systemic lupus erythematosus were reviewed and four cases with unusual ocular manifestations are described. We found that anterior uveitis is not an uncommon manifestation of systemic lupus erythematosus and physicians must be aware of it during the patient's evaluation, since it can be treated without serious visual loss. Optic neuritis is uncommon in systemic lupus erythematosus and visual loss may be permanent despite therapy.

Sialochemistry in juvenile chronic arthritis

Abstract: Stimulated parotid gland secretions collected from 16 patients with juvenile chronic arthritis (JCA) were analysed and the results compared with those obtained from 83 healthy sex-, age-, and socioeconomic status-matched children. Parotid salivary flow rate was measured and the saliva samples were assayed for calcium, phosphorus, potassium, chloride, sodium, urea, lysozyme, amylase and immunoglobulin levels (IgA, Ig, IgM). Our results showed that parotid flow rate (PFR) values in JCA patients were not statistically different from those in healthy controls. However, the mean salivary concentrations of calcium, phosphorus, potassium, lysozyme and IgA were significantly lower in the patients. These data could provide an explanation for the increased incidence of caries and gingivitis observed in JCA.

Modulation of Clostridium perfringens intestinal colonization in infants delivered by caesarean section.

Abstract: The colonization byClostridium perfringens was investigated in 19 infants delivered by caesarean section during the two first weeks of life. The pattern ofC. perfringens colonization depended upon the feeding. Breast feeding led to the repression ofC. perfringens, whereas bottle feeding allowed its maintenance. On the contrary,Bifidobacterium bifidum growth was favoured by breast feeding. However, in one breast-fed infant,B. bifidum was never isolated andC. perfringens decreased. Breast feeding was able to directly modulateC. perfringens numbers. In fact,B. bifidum also had an effect, as demonstrated by the lower mean counts ofC. perfringens, in bottle-fed infants carrying the bifidobacterial flora (p=0.05). None of the bifidobacteria investigated in this study led to the same decrease.