Phosphate glasses for tissue engineering: Part 2. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass fibre system

This paper presents the results of a study of the thermal properties, solubility and dimensions of a range of phosphate-based glass fibres (PB-GFs). The glass compositions were limited by fixing the P2O5 content to 45, 50 and 55 mol%, and varying the CaO mol% at 30, 35 and 40. PB-GFs were obtained from the 50 and 55 mol% P2O5 compositions; however, we were unable to obtain fibres from the 45 mol% compositions. This was linked to the cross-linked density, network connectivity and average chain length of the compositions studied. With regards to thermal parameters investigated, initial data showed an increase of the Tg and crystallisation temperatures with increasing CaO mol% at each fixed phosphate content. A decrease in Tg temperatures was also observed with increasing P2O5 content to 55 mol%. The crystallisation temperatures obtained for compositions with fixed phosphate at 55 mol%, showed a reverse pattern, with a decrease in values as compared to the fixed 50 mol% phosphate compositions. The diameters of the fibres all decreased with increasing RPMs as expected, and the solubility also increased with increasing RPMs. This was related to the increased surface area of the higher RPM fibres. There was also a decrease seen in solubility with increasing CaO mol%.     

Haemophilus ducreyi Outer membrane determinants, including DsrA, define two clonal populations

The Haemophilus ducreyi outer membrane component DsrA (for ducreyi serum resistance A) is necessary for complete resistance to normal human serum (NHS). When DsrA expression in 19 temporally and geographically diverse clinical isolates of H. ducreyi was examined by Western blotting, 5 of the strains expressed a different immunotype of the DsrA protein (DsrA(II)) than the well-characterized prototypical strain 35000HP (DsrA(I)). The predicted DsrA proteins expressed by the DsrA(II) strains were 100% identical to each other but only 48% identical to that of strain 35000HP. In addition to the DsrA(II) protein, class II strains also expressed variant forms of other outer membrane proteins (OMPs) including NcaA (necessary for collagen adhesion A), DltA (ducreyi lectin A), Hlp (H. ducreyi lipoprotein), major OMP, and/or OmpA2 (for OMP A2) and synthesized a distinct, faster-migrating lipooligosaccharide. Based on these data, strains expressing DsrA(I) were termed class I, and those expressing DsrA(II) were termed class II. Expression of dsrA(II) from strain CIP 542 ATCC in the class I dsrA(I) mutant FX517 (35000HP background), which does not express a DsrA protein, rendered this strain resistant to 50% NHS. This demonstrates that DsrA(II) protein is also critical to serum resistance. Taken together, these results indicate that there are two clonal populations of H. ducreyi. The implications of two classes of H. ducreyi strains differing in important antigenic outer membrane components are discussed.     

The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity

BACKGROUND: A self-rating inventory has been developed to measure DSM-IV and ICD-10 diagnoses of major (moderate to severe) depression by the patients' self-reported symptoms. This Major Depression Inventory (MDI) can be scored both according to the DSM-IV and the ICD-10 algorithms for depressive symptomatology and according to severity scales by the simple total sum of the items. METHODS: The Schedule for Clinical Assessment in Neuropsychiatry (SCAN) was used as index of validity for the clinician's DSM-IV and ICD-10 diagnosis of major (moderate to severe) depression. The sensitivity and specificity of MDI was assessed in a sample of 43 subjects covering a spectrum of depressive symptoms. RESULTS: The sensitivity of the MDI algorithms for major depression varied between 0.86 and 0.92. The specificity varied between 0.82 and 0.86. When using the total score of MDI the optimal cut-off score was estimated 26 and the total score was shown to be a sufficient statistic. LIMITATIONS: The sample of subjects was limited. Patients with psychotic depression were not included. CONCLUSION: The MDI was found to have a sensitivity and specificity which is acceptable. The questionnaire is brief and can be scored diagnostically by the DSM-IV and ICD-10 algorithms as well as by its simple total score.     

Combination-sensitive neurons in the medial geniculate body of the mustached bat: encoding of target range information.

1. Delay-tuned combination-sensitive neurons (FM-FM neurons) have been discovered in the dorsal and medial divisions of the medial geniculate body (MGB) of the mustached bat (Pteronotus parnellii). In this paper we present evidence for a thalamic origin for FM-FM neurons. Our examination of the response properties of FM-FM neurons indicates that the neural mechanism of delay-tuning depends on coincidence detection and involves an interaction between neural inhibition and excitation. 2. The biosonar pulse (P) and its echo (E) produced and heard by the mustached bat consist of four harmonics; each harmonic contains a constant frequency (CF) component and a frequency modulated (FM) component. Thus the pulse-echo pair contains eight CF components (PCF1-4, ECF1-4) and eight FM components (PFM1-4, EFM1-4). The stimuli used in this study consisted of CF, FM, and CF-FM sounds: paired CF-FM sounds were used to simulate any two harmonics of pulse-echo pairs. The responses of FM-FM neurons in the MGB were recorded extracellularly. We found that FM-FM neurons respond poorly or not at all to single sounds, respond strongly to paired sounds, and are tuned to the frequency and amplitude of each sound of the pair and to the time interval separating them (simulated echo delay). 3. All FM-FM neurons are facilitated by paired FM sounds and most are facilitated by paired CF sounds. Best facilitative frequencies measured with paired CF sounds fall outside the frequency ranges of the CF components of biosonar signals, whereas best facilitative frequencies measured with paired FM sounds fall within the frequency ranges of the FM components of biosonar signals. Thus FM-FM neurons are expected to respond selectively to combinations of FM components in biosonar signals. The FM components of pulse-echo pairs essential to facilitate FM-FM neurons are the FM component of the fundamental of the pulse (PFM1) in combination with the FM component of the second, third, or fourth harmonic of an echo (EFM2, EFM3, EFM4; collectively, EFMn). 4. The frequency combinations to which FM-FM neurons are tuned reflect small deviations from the harmonic relationship such as occurs in combinations of FM components from pulses and Doppler-shifted echoes. Compared with CF/CF neurons, however, FM-FM neurons are broadly tuned to stimulus frequency. Thus FM-FM neurons are Doppler-shift tolerant and relatively unspecialized for processing velocity information in the frequency domain.(ABSTRACT TRUNCATED AT 400 WORDS)     

Dactinomycin treatment of murine lupus erythematosus. I. Renal disease and longevity.

Three groups of female (NZB X NZW)F1 hybrid mice were treated with an intermittent regimen of dactinomycin (actinomycin D), 3.5 microgram. daily. Median survival was doubled in two of the groups and increased by more than 75 per cent in the third. Most of the treated animals never had significant proteinuria. When kidneys from 14 treated mice, which died between the ages of 11 and 20 months, were examined by light and fluorescence microscopy, most showed the lesions of normal aged CBA and C57BL/6 mice, some expansion of the mesangial matrix and increased cellularity, consistent with deposition of immunoglobulins and complement components in the mesangium, generally sparing the capillary loops. Four of the 14 animals, three of them long-lived, had advanced renal glomerular disease. These data indicate that dactinomycin, by whatever therapeutic mechanism, permits very extended survival of B/W female mice, the large majority of them without significant renal disease.     

Atubular glomeruli in patients with chronic pyelonephritis

In an animal model of chronic nephropathy a large proportion of the apparently normal glomeruli have been shown to be small and without connection to a proximal tubule. The present study examines the degree to which atubular glomeruli are also present in human renal disease. Eleven patients with chronic pyelonephritis (CP) and seven controls were investigated. The number of glomeruli connected to a normal proximal tubule was determined in serial sections and the volumes of individual glomeruli estimated with stereological methods. Only glomeruli with little or no sclerosis were investigated. The volume fractions of proximal tubules and interstitial tissue were estimated using point counting. The results showed that 50% of glomeruli in the CP group were connected to a normal proximal tubule, whereas 35% of the glomeruli were without any recognizable connection to a proximal tubule (atubular glomeruli). The remaining 15% were connected to an atrophic tubule. The mean volume of the glomeruli without a connection to a normal proximal tubule was only half that of glomeruli with a normal proximal tubule. No significant difference was found between the mean glomerular volume in the two groups, but the intraindividual variation of glomerular volumes was larger in the CP group. A significant negative correlation was found in the CP group between the percentage of glomeruli without connection to a normal proximal tubule and the volume fraction of proximal tubules. A significant positive correlation was found between the percentage of glomeruli that were not connected to a normal proximal tubule and the volume fraction of the interstitial tissue. This study shows that atubular glomeruli, which only can be identified in serial sections, constitute a large proportion of glomeruli in chronic pyelonephritis. Their existence could be a major reason for the irreversibility of nonglomerular chronic renal diseases.     

Regional cerebral blood flow after occlusion of the middle cerebral artery

Occlusions of the middle cerebral artery (MCA) are mostly of embolic origin (appr. 80%) and give rise to about one third of all ischemic strokes, most of these being major strokes. MCA occlusions lasting for less than 1/2 h are tolerated without occurrence of permanent tissue damage. Occlusions lasting between 1/2 h to 4-8 h lead to permanent tissue damage and neurological deficits that are proportional to the duration of occlusion. Maximal tissue damage is obtained after 4-8 h occlusion. A cerebral blood flow of 8-23 ml/100 gr/min is sufficient for cellular viability but insufficient for normal tissue function ("ischemic penumbra"). Cellular function is completely abolished in the interval 8-16 ml/100 gr/min and flow at that level is tolerated only for 1-3 h before neuronal death ensues. In the interval 18-23 ml/100 gr/min there is some functional activity although it is reduced. Experimental and clinical evidence suggests that flow in this interval may be tolerated for several days, months or even longer ("chronic ischemic penumbra"). After MCA occlusion the blood flow falls below 8 ml/100 gr/min in most cases and permanent MCA occlusion always leads to relatively large areas of frank infarction. The ischemic infarcts may be surrounded by collaterally perfused areas where the blood flow is pressure-dependent (impaired autoregulation) and quite commonly insufficient for normal neuronal function (below 23 ml/100 gr/min). Such collaterally perfused areas may include a "chronic ischemic penumbra". Emboli causing MCA occlusions commonly disintegrate and/or migrate more peripherally within the first few weeks post stroke. This leads to reperfusion and changes of ischemic infarcts into hyperemic infarcts where flow is severely increased. The vascular reactivity is completely abolished in hyperemic infarcts and the hyperemic state lasts for about two weeks. Probably, anemic infarcts are equivalent to ischemic infarcts while the hemorrhagic variety is equivalent to hyperemic infarcts. The "partial infarct" with selective neuronal necrosis occurs in experimental animals after MCA occlusions of less than four h but not after permanent MCA occlusion. The significance of partial infarction in human stroke is not clarified. The extent of irreversible tissue damage can be reduced only if therapy sets in within 4-8 h after the occlusion. If a "chronic penumbra" exists the extension of reversible tissue damage can be reduced if therapy aimed at increasing the blood flow in the penumbra sets in within weeks or even months after the stroke.(ABSTRACT TRUNCATED AT 400 WORDS)