Development of diabetic macular oedema shows associations with systemic medication - An epidemiological study

PURPOSE

To identify associations between systemic drugs and the incidence of diabetic macular oedema (DME). Of interest was to find beneficial and/or deleterious associations of used drugs.

METHODS

A historic cohort design based on administrative data. Study population consisted of 150 353 individuals with diabetes. Endpoint event was the development of DME (ICD-10 H36.01), censoring events were death or study end December 2017. The follow-up started between 1997 and 2010. The systemic medication consisted of 95 substances. We constructed a nested case-control study design comparing 2630 cases with DME to 13 144 age- and sex-matched controls without DME. Results are reported as odds ratios (ORs) with 95% confidence intervals (CIs) based on conditional logistic regression models.

RESULTS

Incidence rate for DME was 1.80 per 1000 person-years (95% CI 1.73-1.87). In all, we observed a lower incidence rate of DME in females (IRR 0.57; 95% CI 0.52-0.62) compared to males. Exposure to hormone replacement therapy estradiol (OR 0.42; 0.25-0.68), temazepam (0.23; 0.08-0.62) and allopurinol (0.61; 0.43-0.86) were associated with lower risk of DME, while use of insulin or insulin analogue (3.30; 2.99-3.64), sulfonylureas (1.21; 1.05-1.40), diuretic furosemide (1.90; 1.61-2.24), calcium channel blocker amlodipine (1.53; 1.34-1.75), ACE inhibitors ramipril (1.66; 1.46-1.89) and enalapril (1.38; 1.16-1.64) were associated with an increased risk of DME.

CONCLUSIONS

Large-scale studies examining the incidence of DME are lacking. Our findings suggest that associations of systemic medications with the incidence of DME may shed light on the pathogenesis of complex DME, encouraging further studies.

Risk of glaucoma after vitreoretinal surgery - Findings from a population-based cohort study

PURPOSE

To investigate the association between different types of vitrectomy and risk of different types of glaucoma and to determine the effect of systemic medication and diabetes status on this risk.

METHODS

A population-based nested case-control study included individuals of age ≥ 18 years who had undergone single vitrectomy, vitrectomy with retinal procedure, or combined phaco-vitrectomy between 2001 and 2010. End of follow-up was 2017. Odds ratio (OR) for the development of glaucoma after different types of vitrectomy and 95% confidence interval (CI) were based on conditional logistic regression models. For every glaucoma case, five controls were matched by age, sex, start of follow-up year, and hospital district.

RESULTS

The cohort (n = 37 687), of which 52.8% was female, consisted of 6552 individuals diagnosed with glaucoma and 31 135 controls matched by age, sex, and hospital district. Vitrectomy was performed on 103 eyes in the glaucoma group and 158 eyes in the control group. As regards the risk of any glaucoma, the risk was lowest in eyes that underwent combined phaco-vitrectomy (OR: 2.7, 95% CI: 1.8-4.1), followed by single vitrectomy (OR: 3.15, 95% CI: 2.1-4.8), and highest in eyes that underwent vitrectomy with retinal procedure (OR: 4.5, 95% CI: 2.7-7.4). Diabetes had no effect (OR: 0.96, 95% CI: 0.92-1.01), but 5-year systemic statin use slightly decreased glaucoma risk (OR: 0.86, 95% CI: 0.77-0.97).

CONCLUSIONS

Vitreoretinal surgery was associated with an increased glaucoma risk; the risk being related to the complexity of vitrectomy. Long-term systemic statin therapy may decrease glaucoma risk, while diabetes had no association.

Proliferative diabetic retinopathy transcriptomes reveal angiogenesis, anti-angiogenic therapy escape mechanisms, fibrosis and lymphatic involvement

Proliferative diabetic retinopathy (PDR) is a sight-threatening diabetic complication in urgent need of new therapies. In this study we identify potential molecular mechanisms and target candidates in the pathogenesis of PDR fibrovascular tissue formation. We performed mRNA sequencing of RNA isolated from eleven excised fibrovascular membranes of type 1 diabetic PDR patients and two non-diabetic patients with rhegmatogenous retinal detachment with proliferative vitreoretinopathy. We determined differentially expressed genes between these groups and performed pathway and gene ontology term enrichment analyses to identify potential underlying mechanisms, pathways, and regulators. Multiple pro-angiogenic processes, including VEGFA-dependent and -independent pathways, as well as processes related to lymphatic development, epithelial to mesenchymal transition (EMT), wound healing, inflammation, fibrosis, and extracellular matrix (ECM) composition, were overrepresented in PDR. Overrepresentation of different angiogenic processes may help to explain the transient nature of the benefits that many patients receive from current intravitreal anti-angiogenic therapies, highlighting the importance of combinatorial treatments. Enrichment of genes and pathways related to lymphatic development indicates that targeting lymphatic involvement in PDR progression could have therapeutic relevance. Together with overrepresentation of EMT and fibrosis as well as differential ECM composition, these findings demonstrate the complexity of PDR fibrovascular tissue formation and provide avenues for the development of novel treatments.

An Ex Vivo Tissue Culture Model for Fibrovascular Complications in Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and one of the leading causes of blindness in working-age adults. No current animal models of diabetes and oxygen-induced retinopathy develop the full-range progressive changes manifested in human proliferative diabetic retinopathy (PDR). Therefore, understanding of the disease pathogenesis and pathophysiology has relied largely on the use of histological sections and vitreous samples in approaches that only provide steady-state information on the involved pathogenic factors. Increasing evidence indicates that dynamic cell-cell and cell-extracellular matrix (ECM) interactions in the context of three-dimensional (3D) microenvironments are essential for the mechanistic and functional studies towards the development of new treatment strategies. Therefore, we hypothesized that the pathological fibrovascular tissue surgically excised from eyes with PDR could be utilized to reliably unravel the cellular and molecular mechanisms of this devastating disease and to test the potential for novel clinical interventions. Towards this end, we developed a novel method for 3D ex vivo culture of surgically-excised patient-derived fibrovascular tissue (FT), which will serve as a relevant model of human PDR pathophysiology. The FTs are dissected into explants and embedded in fibrin matrix for ex vivo culture and 3D characterization. Whole-mount immunofluorescence of the native FTs and end-point cultures allows thorough investigation of tissue composition and multicellular processes, highlighting the importance of 3D tissue-level characterization for uncovering relevant features of PDR pathophysiology. This model will allow the simultaneous assessment of molecular mechanisms, cellular/tissue processes and treatment responses in the complex context of dynamic biochemical and physical interactions within the PDR tissue architecture and microenvironment. Since this model recapitulates PDR pathophysiology, it will also be amenable for testing or developing new treatments.

The microenvironment of proliferative diabetic retinopathy supports lymphatic neovascularization

Proliferative diabetic retinopathy (PDR) is a major diabetic microvascular complication characterized by pathological angiogenesis. Several retinopathy animal models have been developed to study the disease mechanisms and putative targets. However, knowledge on the human proliferative disease remains incomplete, relying on steady-state results from thin histological neovascular tissue sections and vitreous samples. New translational models are thus required to comprehensively understand the disease pathophysiology and develop improved therapeutic interventions. We describe here a clinically relevant model, whereby the native multicellular PDR landscape and neo(fibro)vascular processes can be analysed ex vivo and related to clinical data. As characterized by three-dimensional whole-mount immunofluorescence and electron microscopy, heterogeneity in patient-derived PDR neovascular tissues included discontinuous capillaries coupled with aberrantly differentiated, lymphatic-like and tortuous endothelia. Spatially confined apoptosis and proliferation coexisted with inflammatory cell infiltration and unique vascular islet formation. Ex vivo-cultured explants retained multicellularity, islet patterning and capillary or fibrotic outgrowth in response to vitreoretinal factors. Strikingly, PDR neovascular tissues, whose matched vitreous samples enhanced lymphatic endothelial cell sprouting, contained lymphatic-like capillaries in vivo and developed Prox1⁺ capillaries and sprouts with lymphatic endothelial ultrastructures ex vivo. Among multiple vitreal components, vascular endothelial growth factor C was one factor found at lymphatic endothelium-activating concentrations. These results indicate that the ischaemia-induced and inflammation-induced human PDR microenvironment supports pathological neolymphovascularization, providing a new concept regarding PDR mechanisms and targeting options. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Effector memory T-cells dominate immune responses in tuberculosis treatment: antigen or bacteria persistence?

OBJECTIVE

To compare ex vivo immunological responses upon stimulation of lymphocytes with Mycobacterium tuberculosis-specific antigens in three groups: 1) subjects diagnosed with tuberculosis (TB) in the early 1940s and 1950s but who did not receive anti-tuberculosis chemotherapy (n = 5), 2) subjects treated with anti-tuberculosis agents prior to the rifampicin (RMP) era (n = 26) and 3) subjects who received RMP as a part of modern combination therapy (n = 7).

DESIGN

A total of 38 healthy subjects, mean age 70 +/- 13 years, with a history of previously treated TB were recruited. Peripheral blood mononuclear cells were collected and analysed as a batch by ELISpot. Representative samples with high reactivities were further immunophenotypically characterised.

RESULTS

No differences between the studied groups were detected with regard to the frequencies of reactive lymphocytes. The dominant immunophenotypic profile of the representative responders, irrespective of the treatment schemes, was CD4+CD45RO+CD45RA-CD27-CD28-CCR7-, compatible with the fast reacting effector memory T-cell lineage (T(EM)).

CONCLUSION

Specific T(EM) cells persist even in subjects treated for TB decades ago with modern anti-tuberculosis chemotherapy. Additional studies are needed to address the question of what drives the survival of T(EM) after adequate treatment: persistence of antigens or bacteria.

Altered phospholipid-apoB-100 interactions and generation of extra membrane material in proteolysis-induced fusion of LDL particles

Lipid droplets and membrane material are produced in the extracellular matrix of the arterial intima during atherogenesis. Both in vitro and in vivo experimentation suggests that fusion of modified LDL particles leads to formation of such lipid droplets. Here we applied proton NMR spectroscopy to probe surface phospholipids phosphatidylcholine (PC) and sphingomyelin (SM) of LDL particles during proteolytic degradation of apolipoprotein B-100 (apoB-100). Initiation of apoB-100 degradation was accompanied by the abruptly increased intensity of the choline -N(CH(3))(3) resonance of PC molecules, indicating disruption of their interactions with apoB-100. However, subsequent particle fusion was accompanied by a steady decrease in the intensity of the choline resonances of both PC and SM. Electron microscopy of the proteolyzed LDL revealed irregularly shaped multilamellar membranes attached to aggregates of fused particles. This suggests formation of membrane material with low hydration, in which some of the atomic motions are hindered. Characterization of the behavior of the surface lipids of LDL particles during apoB-100 degradation and other types of LDL modification will aid in understanding molecular mechanisms leading to fusion and generation of multilamellar membrane material in the arterial intima during atherogenesis.

Remodeling of HDL by phospholipid transfer protein: demonstration of particle fusion by 1H NMR spectroscopy

There is evidence that phospholipid transfer protein (PLTP) can increase reverse cholesterol transport by inducing favorable subclass distribution in the high density lipoprotein (HDL) fraction. This includes generation of initial cholesterol acceptor particles, pre beta-HDL, and of enlarged particles that are rapidly cleared from the circulation. However, partly because of methodological difficulties, the mechanisms behind the PLTP-mediated interconversion of HDL particles are not fully understood. In this communication, we describe the use of a novel methodology, based on 1H NMR spectroscopy, to study the PLTP-induced size changes in the HDL particles. In accordance with native gradient gel electrophoresis, the 1H NMR data revealed a gradual production of enlarged HDL particles in the HDL3+ PLTP mixtures. In addition, according to a physical model for lipoprotein particles, relating the frequency shifts observable with NMR to the size of the lipoprotein particles, the NMR data demonstrated that PLTP-mediated HDL remodeling involves fusion of the HDL particles.

Detection of low density lipoprotein particle fusion by proton nuclear magnetic resonance spectroscopy

Recent evidence suggests that fusion of low density lipoprotein (LDL) particles is a key process in the initial accumulation of lipid in the arterial intima. In order to gain a better understanding of this early event in the development of atherosclerosis, it would thus be necessary to characterize the process of LDL fusion in detail. Such studies, however, pose severe methodological difficulties, such as differentiation of particle fusion from aggregation. In this paper we describe the use of novel methodology, based on 1H NMR spectroscopy, to study lipoprotein particle fusion. To test the methodology, we chose proteolytic fusion of LDL particles, an in vitro model that has been well characterized in our laboratory. The spectroscopic data suggested that proteolysis of LDL with alpha-chymotrypsin induced slow initiation of fusion, which was followed by particle fusion at an increased rate. Moreover, 1H NMR spectroscopic data on different kinds of LDL interactions, for example, when LDL formed aggregates with antibodies against human apolipoprotein B-100, were obtained and compared with the electron microscopic characteristics of these preparations. An important finding was that limited aggregation of LDL particles did not disturb the 1H NMR spectroscopic parameters used for the detection of particle fusion and preserved the physico-chemical information on the particles. The 1H NMR methodology developed is sensitive to and specific for low density lipoprotein (LDL) fusion and may also allow for studies of the fate of LDL particles in other in vitro preparations that mimic the arterial interactions in vivo.

Accumulation of strontium and fluoride in approximal dental plaque and changes in plaque microflora after rinsing with chlorhexidine-fluoride-strontium solution

OBJECTIVES

To find out if strontium is incorporated into plaque and enamel in vivo during a 2-week rinsing period with a chlorhexidine-fluoride-strontium solution and to determine the effects of the rinsing on the numbers of mutans streptococci and lactobacilli in plaque.

SUBJECTS AND METHODS

A total of 18 adult participants rinsed their mouths twice a day for 2 weeks, first with a placebo solution and subsequently, separated by a 1-week interval without rinsing, with a chlorhexidine gluconate (0.05%)-sodium fluoride (0.04%)-strontium (100 ppm as SrCl2) rinsing solution (CXFSr) for another 2 weeks.

RESULTS

After the CXFSr rinsing period the strontium and fluoride contents (microgram g-1 plaque dry weight; mean +/- sr) of approximal plaque were 32.5 +/- 4.7 and 72.8 +/- 9.0, compared with the respective contents of 8.4 +/- 1.2 and 42.0 +/- 4.8 after placebo rinsing (P = 0.0001 for both comparisons). The strontium content remained elevated for 6 weeks. The median proportion of mutans streptococci of approximal plaque of the total viable count of bacteria was 1% after placebo rinsing but decreased to 0.2% after CXFSr rinsing. The proportion of mutans streptococci remained low at 3 weeks (P = 0.018 vs placebo) but had reached the placebo level at 6 weeks. Rinsing with CXFSr solution did not reduce lactobacilli in plaque. The strontium or fluoride contents of the enamel surfaces subjected to tooth brushing did not significantly change.

CONCLUSIONS

Strontium and fluoride accumulated in dental plaque during a 2-week CXFSr rinsing period and the proportion of mutans streptococci in approximal plaque was reduced at least for 3 weeks after completion of the rinsing.

[The Oulu University Hospital has developed day case surgery for children]

After several changes the children's day surgery was moved to new premises--to the day case surgery unit. Due to these changes there was an excellent opportunity to question the former care practices and to "turn over a new leaf" in the new premises. Care is implemented according to primary nursing. The primary nurse cares for the patient/ the family from hospitalization to discharge. Individuality, family-centerdness, safety and comprehensiveness are emphasized. The personnel and the patients are satisfied with the changes in care practices.

Assessment of cholesteryl ester transfer protein function in lipoprotein mixtures by 1H NMR spectroscopy

Studies of cholesteryl ester transfer protein (CETP) function in lipoprotein mixtures pose many difficulties by conventional biochemical methods. For instance, studies on the effects of CETP on the composition of apolipoprotein B containing lipoproteins (very low and low density lipoproteins) in lipoprotein mixtures are tedious due to repeated ultracentrifugational isolations and have thus rarely been performed. Here we present a new 1H NMR spectroscopy technique to assess the CETP function in lipoprotein mixtures. This technique does not require repeated physical isolations of the lipoprotein particles but uses mathematical separation of the fractions on the basis of biochemical prior knowledge based lineshape fitting analysis of specific lipid resonances in the 1H NMR spectra. The lipoproteins are separated according to their size related chemical shift which allows for distinct quantification between very low and low density lipoproteins, the two major apolipoprotein B containing fractions. The methodological basis of the technique is discussed here together with a demonstration that this kind of approach allows dynamic follow up of the lipid transfer reactions in complex lipoprotein and CETP mixtures. The results revealed a consistent behaviour which corroborated the recent findings suggesting that the neutral lipid mass transfer among lipoproteins is not an equimolar heteroexchange.

Effects of dietary fluoride and magnesium supplements on cyclic adenosine monophosphate (cAMP), calcium and magnesium levels in aorta of genetically hypercholesterolaemic RICO rats

Previous observations have suggested that low intakes of fluoride prevent pathological calcifications of internal organs, including the aortic wall, in experimental animals, fed a basically low magnesium diet. Our group found recently that fluoride has some potentially preventive effect against atherosclerotic serum lipid profiles in genetically hypercholesterolaemic rats. To study whether the apparently positive potential of fluoride against atherosclerosis is also reflected in aortic tissue, through its well known activation of adenylate cyclase, the aortic cAMP content of the rats used in our recent study was determined. Out of a total of 56 male RICO rats, mean weight 160 g, the control group C was fed an adequate diet, with 44% sucrose, a magnesium content of 883 p.p.m. and with 0.5% cholesterol. Group D had the same diet as group C except that the magnesium content was reduced to 200 p.p.m. Group E had the same diet as group D but with the fluoride content elevated from 1.9 to 12 p.p.m. Group G had the same diet as group E but with the magnesium content elevated from 200 to 300 p.p.m. After a feeding period of 6 weeks, the aortas of the animals were removed, cleaned and kept at -70 degrees C until analysed. The mean cAMP content of the aortas, measured by radioimmunoassay, in groups C, D E and G was 439, 546, 681, and 1394 mumol mg-1 protein, respectively. In group G only, the cAMP content was significantly higher than that of the other groups (p < 0.001). The mean calcium and magnesium contents of the aortas of different groups did not significantly differ from each other. Thus in RICO rats, fed a high-sugar low-magnesium diet with cholesterol, supplementation of the diet with a small amount of fluoride elevates the cAMP content of the aorta, provided that the intake of Mg is not very low.

Identification of Bacteroides forsythus in subgingival dental plaque with the aid of a rapid PCR method

Bacteroides forysthus has been shown to be prevalent among patients with periodontitis. Conventional microbiological methods used to identify this bacterium, however, are laborious and time-consuming and are therefore not well-suited for screening purposes. We have developed a polymerase chain-reaction (PCR) method which is rapid, specific, and simple to perform and does not require other sample pre-treatment except a brief centrifugation. This method was applied to the detection of B. forsythus in subgingival plaque of 58 periodontitis patients. When compared with the results of conventional culturing, the PCR method always confirmed the culture-positive results, while none of the PCR negative samples was shown to be culture-positive. The PCR method appeared to give more than double the number of samples positive for B. forsythus than culturing (89.7% vs. 37.9%). The analysis requires less than 4 hrs to perform, and is specific only to B. forsythus and sensitive enough to detect fewer than 5 bacteria.

Simultaneous detection of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis by a rapid PCR method

The identification of periodontal pathogens by conventional methods is time-consuming and difficult. Therefore, a multiplex PCR method for simultaneous detection of Actinobacillus actinomycetemcomitans (A.a.) and Porphyromonas gingivalis (P.g.) was developed for rapid and easy determination of these risk-indicator bacteria in human periodontal disease. The PCR primers were designed to hybridize to various regions of 16S rRNA genes, and a hot-start technique was used to obtain maximum sensitivity and specificity. This method can detect both of these bacteria in subgingival plaque samples at concentrations as low as 5 to 50 cells per sample. The sensitivity, however, was even 10 times better when the bacteria were analyzed in a water suspension. Since the only step between sample collection and the actual analysis is a brief centrifugation of the patient sample, the detection can be readily carried out in four hours. The performance of the method was studied with 36 patient samples. The results showed that the PCR method detected A.a. (44% vs. 25%, respectively) and P.g. (56% vs. 42%, respectively) more often than the conventional culture in plaque samples. Thus, our multiplex PCR method is rapid and more effective than conventional protocols in detecting these periodontal pathogens.

Serum lipoprotein levels in genetically hypercholesterolaemic RICO rats: effects of a high-sucrose-cholesterol diet without or with altered magnesium and fluoride content

Genetically hypercholesterolaemic RICO rats (male, 6 weeks old) were randomly distributed into 6 experimental groups. The zero-time basal group A was sacrificed at the start of the experiment while the other groups were fed for 6 weeks and then sacrificed. Group B was fed a stock diet. Control group C was fed a high-sucrose (45%) diet with 0.5% added cholesterol. In the diet of group D, only the magnesium (Mg) content was reduced from the level of group C (883 ppm) to 200 ppm. The diet of group E was the same as that of group D with the addition of 12 ppm of fluoride (F) and the diet of group G was the same as that of group E, but with its Mg content elevated from 200 ppm to 300 ppm. Analysis of aortic blood samples, taken before sacrifice, indicated significant increases in total serum cholesterol (p < 0.01), very low density lipoprotein (VLDL) (p < 0.001) and low density lipoprotein (LDL), (p < 0.001) cholesterol, and a trend to lower high density lipoprotein (HDL) cholesterol in group C, as compared to group B. Significantly lower total (p < 0.05), VLDL (p < 0.01) and LDL (p < 0.01) triglycerides were observed in group C when compared to group B. The LDL phospholipids were significantly higher in group C (p < 0.001) than in group B. When cholesterol levels in groups D, E and G were compared with group C, the VLDL cholesterol in group E and the LDL cholesterol in group G were slightly but significantly (p < 0.05) reduced, while total cholesterol and the other subfractions were unaltered. The LDL triglycerides of groups E and G were significantly smaller still than the already small fraction in group C. The VLDL triglyceride in group E was significantly lower than that of group C (35% reduction, p < 0.001), D and G (p < 0.05). Phospholipids were slightly but significantly reduced in the VLDL fraction of group E and in the LDL fraction of group G (p < 0.05 and 0.01, respectively), as compared to those of group C.

Development of a rapid PCR method for identification of Helicobacter pylori in dental plaque and gastric biopsy specimens

A rapid and simple polymerase chain reaction (PCR) method was developed to detect Helicobacter pylori in gastric biopsy specimens and dental plaque samples. The primers were targeted to the 16S rRNA sequence of Helicobacter pylori strain ATCC 43504. The system was found to have a theoretical detection level of 0.5 to 5 Helicobacter pylori cells in a 5 microliters sample of dental plaque. In the absence of plaque, the detection level was even better: theoretically, 0.05 to 0.5 Helicobacter pylori cells were detected in water suspension. However, this appeared to be due to the presence of free bacterial DNA in the culture used for the sensitivity determination. Thus, the actual sensitivity of the system was found to be fewer than five Helicobacter pylori cells, irrespective of the type of sample used. The method was then used to analyse 29 dental plaque and gastric biopsy specimens collected from patients with a history of recurrent peptic ulcer disease. Fourteen stomach specimens were positive for Helicobacter pylori when tested with the PCR method, while the respective figures with culture, histological examination and the urease test were 11, 12 and 9. No positive dental plaque samples were observed.

Effect of Lactobacillus rhamnosus strain GG (ATCC 53103) on the growth of Streptococcus sobrinus in vitro

Lactobacillus GG, a recently characterized L. rhamnosus GG strain (ATCC 53103), has been shown to exert inhibitory activity against a variety of bacterial species, including streptococci. We isolated and studied the effect of the inhibitory substance of Lactobacillus GG on some oral streptococci. The inhibitory activity of the isolated substance was weak, but some growth inhibition was observed in Streptococcus sobrinus pretreated with the substance in comparison with untreated controls. Zones of growth inhibition on agar plates were apparent only at pH values below 5, indicating that the inhibitory activity was restricted to a low pH range. Growth curve experiments showed a statistically significant inhibition between series with and without the isolated substance (P < 0.05). The ultrastructure of S. sobrinus was not affected when treated with the inhibitory substance. The Lactobacillus GG itself did not ferment sucrose. The results offer interesting perspectives for future research focusing on the protective function of normal flora and in the attempt to replace harmful bacterial species in oral microflora with less harmful ones.

Inhibitory effect on S. mutans by fluoride-treated conventional and resin-reinforced glass ionomer cements

The aim of the present study was to study the effect of fluoride gel treatment on fluoride release and inhibition of acid production of Streptococcus mutans by different glass ionomer cements. Test slabs of four glass ionomer materials were fitted into the bottom of a test tube. A layer of S. mutans cells was centrifuged onto the test slabs, and the specimens were incubated for 4 h in 1.7% sucrose solution. Incubations were made using fresh, aged (29 d), aged and F-treated (1.25% F-gel), and aged, F-treated and aged samples (n = 15 per group). After each incubation, pH and F contents of the fluid phase were determined. The freshly mixed glass ionomer samples released large amounts of fluoride, and the pH fall in the fluid phase was significantly inhibited. For aged samples, the fluoride release decreased strongly and no inhibitory effect on acid production by S. mutans was seen. After application of fluoride gel, fluoride release and inhibitory effect were significantly higher than initially for all glass ionomer cements. In conclusion, all glass ionomer cements were able to take up fluoride and subsequently release it, which resulted in reestablishment of their antibacterial effect. The patterns of fluoride release and antibacterial action were virtually the same for conventional and resin-reinforced glass ionomer cements.

1H NMR-based absolute quantitation of human lipoproteins and their lipid contents directly from plasma

A new method is presented for absolute quantitation of lipid and protein contents of human lipoproteins directly from plasma. The method enables complete lipoprotein lipid profiles to be obtained in a total time of less than one hour. Absolute concentrations of triglycerides, phospholipids, total cholesterol, free cholesterol, esterified cholesterol, total proteins, and total masses can be estimated for the very low density (VLDL) and low density (LDL) lipoprotein fractions. For the high density lipoprotein (HDL) fraction all components except triglycerides can be quantitated. The method is a combination of 1H NMR spectroscopy and a sophisticated lineshape fitting analysis technique. In this paper we present the calibration of the method using 15 plasma samples followed by a double-blind test of 51 plasma samples from 43 individuals. In total, 66 plasma samples were analyzed. Comparison of the 1H NMR-based results with the data of the biochemical assays showed excellent agreement; the correlation coefficient for VLDL triglycerides was 0.98, for LDL cholesterol 0.88, and for HDL cholesterol 0.93. This method can be directly integrated to many kinds of biomedical NMR studies to offer additional biochemically important quantitative lipoprotein information, the measurement of which is usually too laborious by conventional biochemical methods and too high-priced to be adapted into the study protocols. Moreover, the method also has considerable potential to be developed for a routine clinical assay.

Enamel dissolution in relation to fluoride concentrations in the fluid of dental plaque-like layers of precultured Streptococcus sobrinus

Two experiments were conducted to find out what concentration of fluoride (F), when added as NaF to the fluid of an in vitro caries model, would be sufficient for full protection of the underlying enamel during a long (20 or 40 h) fall in 'plaque' pH. An existing caries model with bovine enamel and Streptococcus sobrinus 'plaque' was employed, while the fluid phase was initially either fully or partially saturated with tricalcium phosphate. In the model with fully saturated and more strongly buffered fluid, a 10 parts/10(6) addition of F to the fluid phase caused no inhibition of the pH fall. In the model with partially saturated and weakly buffered fluid, prevention of the pH fall increased along with increase of added F from 2 to 20 parts/10(6). In each model, the 10 parts/10(6) addition of F was associated with complete prevention of the increase of calcium (Ca) in the fluid phase. In the partially saturated, weakly buffered model, findings on the inorganic P of the fluid phase agreed with findings on Ca. The findings for microhardness of the enamel surface indicated a complete prevention of the enamel softening through the 10 parts/10(6) F additive. Enamel F content was elevated by the fermentation, and even more so when F was added with sugar to the fluid phase. The Ca content of Strep. sobrinus cells was reduced when incubated with sucrose for 40 h and, especially, with sucrose and F.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of nephropathia epidemica: three cases

Haemorrhagic fever with renal syndrome (HFRS) in Scandinavia is called nephropathia epidemica (NE), and is caused by the Puumala-virus, which belongs to the Hanta-virus genus. The clinical course of NE is mostly benign, complications are uncommon, and deaths are rarely observed. We report the cases of three patients who developed serious complications in the course of NE caused by the Puumala-virus. One patient died within 24 h after admission, another developed progressive neuromuscular dysfunction (Guillain-Barré syndrome) which required auxiliary ventilation for several weeks before a slow recovery, and a third patient developed empty sella syndrome with pituitary gland insufficiency. In the first two cases the diagnosis of NE was confirmed by a rapid avidity assay for IgG antibody against Puumala-virus. In the third case the clinical course, and demonstration of NE immunity 16 years later, suggested that NE might have caused the hypopituitarism. Some patients with NE caused by the Puumala-virus may require intensive-care treatment, and the development of late complications such as empty sella syndrome and hypopituitarism should be taken into consideration.

Embryotoxic effects of eight organic peroxides and hydrogen peroxide on three-day chicken embryos

Nine peroxides were tested for embryotoxicity in 3-day chicken embryos using the air-chamber method. The potencies were expressed by the ED50 for the total embryotoxic effect of the chemicals, including deaths and malformations, up to Day 14 of the incubation. The range of the ED50's was from 0.13 to 2.7 mumoles per egg and the order of the potencies was as follows: cyclohexanoneperoxide greater than cumolhydroperoxide greater than ethylmethylketoneperoxide greater than dibenzoylperoxide greater than acetylacetoneperoxide greater than perbenzoic acid-tert-butylester greater than dicumylperoxide greater than dilauroylperoxide greater than hydrogen peroxide. All nine peroxides caused malformations at a moderate frequency. The maximum percentage of malformed embryos of the treated varied from the 16% of perbenzoic acid-tert-butylester to the 56% of dicumylperoxide. The high percentage caused by the latter could, however, result from slow diffusion of high lethal doses from the air chamber to the embryo.

Toxicity of rubber chemicals towards three-day chicken embryos

Three-day chicken embryos were exposed to 80 different rubber chemicals dissolved in either acetone or water. The following classes of chemicals were studied: thiurams, dithiocarbamates, thioureas, benzothiazoles, benzenesulfohydrazide, dithiodimorpholine, amines, acrylates, guanidines, resorcinol, phthalates, adipates, phosphates, oils, peroxides, heavy metal salts, and sodium nitrite. Dose-response curves and median lethal doses (LD50) or median effective doses (ED50) were calculated for mortality in 2 d after the treatment, for total mortality in 11 d after the treatment, and for the total effect, including deaths and malformations 11 d after the treatment, when the test was finished. Sixteen of the chemicals had no effect on the embryos when injected into the air chamber. Incomplete and irregular dose-response curves for the total effect were obtained with 13 of the chemicals. For them, the ED50 could be calculated. Among the remaining 51 chemicals, the most potent were the dithiocarbamates and cadmium and copper acetates, with the total effect ED50 from 2.4 to 160 nmol/egg. Other chemicals that had an ED50 smaller than 100 nmol/egg were thiurams, cyclohexylthiophthalimide, acrolein, and dithiodimorpholine. The majority of the chemicals had an ED50 between 100 nmol/egg and 10 mumol/egg. The least potent were sodium nitrite and methylmethacrylate with an ED50 of 22 mumol/egg. All the 64 embryotoxic chemicals caused malformations with only one exception (dibutylthiourea). The maximum observed frequencies of malformed embryos varied from 3 to 100% of the treated embryos.

Embryotoxicity of sixteen industrial amines to the chicken embryo

Sixteen amine compounds that are used in the rubber industry, and sodium nitrite, were tested on three-day chicken embryos for embryotoxicity. The parameters measured were: early deaths recorded within two days of injection, late deaths of malformed embryos, late deaths of non-malformed embryos and malformed survivors. The most embryotoxic chemicals were N-phenyl-N'-isopropyl-p-phenylenediamine, N,N,N-triethylethylenediamine, N,N'-dicyclohexyl-p-phenyleneamine and triethylamine, with total effect ED50 values, including deaths and malformations, between 0.11 and 0.90 mumol per egg. The ED50 values for triethylenetetramine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, triethanolamine, N-phenyl-2-naphtylamine, aniline and N-nitrosodiphenylamine ranged from 1.1 to 7.0 mumol per egg. Sodium nitrite was the least potent, with an ED50 of 22 mumol per egg. Six chemicals produced no effects. They probably did not reach the embryo. The four most potent chemicals, together with aniline, caused the highest frequencies of malformations.

Embryotoxic effects of acrolein, methacrylates, guanidines and resorcinol on three day chicken embryos

Acrolein, four methacrylates, two guanidine compounds and resorcinol were tested for embryotoxicity on three day chicken embryos. The most potent chemical was acrolein, with the ED50 0.05 mumol per egg for the total effect, including deaths and malformations. The substances next in potency were N,N'-di-o-tolyl-guanidine and N,N-diphenylguanidine, with ED50 values 0.17 and 0.20 mumol per egg, respectively. Resorcinol and the methacrylates had ED50 values ranging from 2.4 to 22.0 mumol per egg. Acrolein, diphenylguanidine, tetrahydrofururylmethacrylate and trimethylolpropanetrimethacrylate caused the largest amounts of malformed embryos.

Embryotoxic effects of phtalic acid derivatives, phosphates and aromatic oils used in the manufacturing of rubber on three day chicken embryos

Several chemicals that are used for manufacturing of rubber were tested for embryotoxicity on three day chicken embryos. Cyclohexylthiophtalimide was the most potent of the chemicals, with an ED50 value for the total embryotoxic effect 0.04 mumol (10 micrograms) per egg. Phtalic anhydride was about ten times less potent, having the total ED50 for total embryotoxicity 0.38 mumol (56 micrograms) per egg. Two esters of phtalic acid, dibutylphtalate and butylbenzylphtalate, instead, were relatively impotent, with ED50 values of about 33 mumoles and 27 mumoles per egg, respectively. Two phosphates, tricresylphosphate and synthetic arylphosphate, were not potent embryotoxic agents in the chick embryos. They had ED50 values of 7.0 mumoles (2.6 mg) per egg and 9.5 mg per egg, respectively. Sodium phosphate (NaH2PO4) had the ED50 11 mumoles per egg. Three types of oils were tested, too. A mixture known as "highly aromatic oils" was the most potent, with the ED50 31 micrograms per egg. "Low aromatic, paraffin base oils" was the next potent, with the ED50 87 micrograms per egg, while "naphtenic oils" had the ED50 480 micrograms per egg. Cyclohexylthiophtalimide and phtalic anhydride caused malformations at high frequency. The oils and tricresylphosphate appeared to be efficient teratogens under the experimental conditions used.

Embryotoxicity of industrial chemicals on the chicken embryo: dithiocarbamates

Seven dithiocarbamates and three acetates were tested for teratogenicity and lethality in three-day chicken embryos. These included: cadmium diethyldithiocarbamate (CdDE), zinc diethyldithiocarbamate (ZnDE), zinc ethylphenyldithiocarbamate (ZnEP), zinc dibutyldithiocarbamate (ZnDB), copper dimethyldithiocarbamate (CuDM), tellurium diethyldithiocarbamate (TeDE), and piperidine pentamethylenedithiocarbamate (PPM), cadmium acetate (CdAC), copper-(II)acetate (CuAC), and zinc acetate (ZnAC). The parameters measured were early deaths, recorded within two days of injection, late deaths of malformed embryos, late deaths of nonmalformed embryos, and malformed survivors. The order of embryotoxicity decreased as follows: CdAC greater than CdDE greater than ZnDE greater than or equal to ZnEP greater than or equal to ZnDB greater than CuDM greater than TeDE greater than CuAC greater than PPM greater than ZnAC. The only exception to this order was the relatively weak teratogenicity of the metal acetates as compared to dithiocarbamates. Cadmium and zinc dithiocarbamates were potent embryotoxic agents eliciting lethality and malformations at doses of 1 to 10 nmole per egg. Most embryonic deaths occurred at stages 29 to 31, and most of the dead embryos were malformed.

Embryotoxicity of industrial chemicals on the chicken embryo: thiourea derivatives

Six thioureas: 1,3-diphenylthiourea (DPTU), 1,3-dibutylthiourea (DBTU), tetramethylthiourea (TEMTU), trimethylthiourea (TRIMTU), 1,3-diethylthiourea (DETU), and 1,3-ethylenethiourea (ETU), were tested, in addition to carbon disulfide, on three day chicken embryos for embryotoxicity. The parameters measured were early deaths, recorded within two days of injection, late deaths of malformed embryos, late deaths of non-malformed embryos, and malformed survivors. The order of total embryotoxicity decreased as follows DBTU greater than DPTU greater than TEMTU greater than TRIMTU greater than DETU greater than ETU. The range for ED50 values for total embryotoxicity was from 0.28 (DBTU) to 4.5 (ETU) mumol/egg. DBTU caused early deaths but no malformations. TEMTU and DPTU were the most potent teratogens.

Application of the chicken embryo in testing for embryotoxicity: thiurams

A test protocol was developed for the testing of chemicals for toxicity on the chicken embryo. The protocol called for a continuous monitoring of the developing embryo for those that died before maceration. The eggs were injected on day 3, and the test was continued up to day 14 of incubation. The following parameters of embryotoxicity were used: early deaths (spanning the first 2 d after injection), late deaths with malformed embryos, late deaths with nonmalformed embryos, and malformed survivors. The order of embryotoxic potency, in descending order, among the thiurams was tetramethylthiuramdisulfide, tetramethylthiurammonosulfide, tetraethylthiuramdisulfide. It was found that late deaths were seen in 70% of the cases with malformations. The most common types of malformations were eye defects and open coeloms. Dead embryos frequently had multiple malformations. In lethal cases, embryonic development terminated at stages 25/26 and 29 on the Hamburger-Hamilton scale.