An Ex-Vivo Model for Investigating Bacterial Extrusion from Infected Root Canals during Masticatory Function

INTRODUCTION

The extrusion of bacteria from infected root canals may lead to increase in symptoms, expansion of periapical lesions, and contribution to systemic diseases. The aim of this study is to investigate a potential proof-of-concept model to study the extent to which bacteria can escape from infected root canals under dynamic loading (simulated chewing).

METHODS

The study was completed in 2 experiments performed at 2 institutions. Biofilms of Streptococcus intermedius in the first experiment and S. intermedius and Actinomyces naeslundii were allowed to grow in root canals of single-rooted extracted teeth for 3 weeks. The roots of the teeth were suspended in a small chamber containing dental transport medium and were mounted on a lower sample holder of a chewing simulator. In the experimental group, simulated chewing cycles equivalent to 1 year of function were conducted, and then bacterial migration was quantified and compared with stationary teeth.

RESULTS

All experimental samples of the loading group revealed bacterial penetration in both experiments. Several of the unloaded samples revealed no bacterial penetration. In the first experiment, a significantly higher number of bacteria were able to escape into the periapex of the loaded group compared with the unloaded group (P = .017). In the second experiment, there was no significant difference between the 2 bacterial species used in the amount of extruded bacteria; however, there was a highly significant effect for occlusal loading (P = .0001).

CONCLUSIONS

The potential for occlusal forces to enhance bacterial extrusion from infected root canals should be further explored.

Effects of Particle Abrasion Media and Pressure on Flexural Strength and Bond Strength of Zirconia

OBJECTIVES

To compare the effects of particle abrasion medium and pressure on shear bond strength and biaxial flexural strength of three generations of zirconia (Lava Frame, Lava Plus, and Lava Esthetic) with the goal of optimizing the bond to zirconia.

METHODS

280 discs (14 mm diameter; 1 mm thickness) of each zirconia were milled and sintered. Specimens of each material were randomly distributed into 14 groups (n=20); half were tested for shear bond strength and half were tested for biaxial flexural strength. The specimens were particle abraded on one surface by 2 different media (50 μm alumina particles or 50 μm glass beads) for 10 seconds at three different pressures (15, 30, and 45 psi or 0.1, 0.2, 0.3 MPa). Untreated specimens served as positive control. A tube (1.50 mm diameter) filled with dual cured resin cement (Panavia SA) was placed onto the surface and light cured. Specimens were stored in water (37°C for 24 hours) and shear bond strength was measured in a universal testing machine (Instron). Biaxial flexural strength of each specimen was measured according to ISO 6872. Shear bond strength and biaxial flexural strength were compared individually with a 2-way analysis of variance (ANOVA) for factors surface treatment and zirconia composition.

RESULTS

Significant differences were seen between surface treatments (p<0.01), zirconia composition (p<0.01) and their interaction (p<0.01) for both bond strength and flexural strength. With alumina particle abrasion, higher pressure produced higher bonds for Lava Frame and Lava Plus zirconia while the bond of Lava Esthetic declined with increased pressure. Higher pressure (>0.2 MPa or 30 psi) with alumina decreased biaxial flexural strength with Lava Esthetic zirconia.

CONCLUSIONS

Particle abrasion with alumina produced a significantly better combination of bond strength while maintaining biaxial strength of three zirconia materials than particle abrasion with glass beads. The bond strength also depended upon the pressure of particle abrasion and the generation of zirconia used.

Cleaning Zirconia Surface Prior To Bonding: A Comparative Study of Different Methods and Solutions

PURPOSE

To evaluate resin cement bond strength after removal of salivary contamination from a zirconia surface using different cleaning solutions and air-borne particle abrasion.

MATERIALS AND METHODS

One-hundred and twenty zirconia specimens (KATANA STML, Noritake) were prepared and divided into 12 groups (n = 10). Groups were subjected to a notched-edge shear bond strength test (ISO 29022) to analyze the bonding efficiency of a resin cement (Panavia V5, Kuraray Noritake Dental Inc.) before and after contamination with saliva. Group 1 (control) was prepared and cemented without salivary contamination. Group 2 was coated with ceramic primer (Clearfil Ceramic Primer Plus, Kuraray Noritake Dental Inc.) then subjected to salivary contamination then tested. Group 3 was contaminated, cleaned by air-borne particle abrasion, ceramic primer and resin cement applied, and tested. Groups 4 to 12 were contaminated, and then different cleaning solutions (water, 4.5% hydrofluoric acid, 35% phosphoric acid, Ivoclean, KATANA cleaner, Zirclean, sodium hypochlorite 4%, and 7.5%) were used to decontaminate the zirconia surface, followed by ceramic primer, resin cement application, and tested. One-way ANOVA and Tukey post-hoc analysis was used to analyze the data.

RESULTS

One-way ANOVA showed statistical differences among cleaning procedures (p < 0.001, F = 13.48). Air-borne particle abrasion was the only group which provided a bond strength (21 ± 2.8 MPa) that was not statistically different than the control group in which no contamination occurred (25.3 ± 3.3 MPa) (p = 0.247). The use of hydrofluoric acid and zirconia cleaning solutions resulted in bond strengths values which were not statistically different from each other (17.5-19.1 MPa).

CONCLUSION

Air-borne particle, zirconia cleaning solutions and hydrofluoric acid are feasible to decontaminate the zirconia surface from saliva prior to bonding the restoration.

New High-Translucent Cubic-Phase-Containing Zirconia: Clinical and Laboratory Considerations and the Effect of Air Abrasion on Strength

Fabricating all-ceramic restorations with minimal or no application of a secondary phase while maintaining esthetics has been a sought-after goal of the dental profession. The objective has been development of a monolithic material with optical properties similar to the natural tooth without the need for layering porcelain. This article examines some of the newer cubic zirconia materials used in a monolithic form. The authors discuss laboratory-processing issues that affect esthetics, including evaluation of colorizing, sintering, finishing, and polishing, and assess initial translucency testing of several materials while evaluating the effect of air abrasion on flexural strength of these cubic zirconias. Lastly, the article demonstrates an anterior single-unit monolithic case with several of the newer materials.

The wear of polished and glazed zirconia against enamel

STATEMENT OF PROBLEM

The wear of tooth structure opposing anatomically contoured zirconia crowns requires further investigation.

PURPOSE

The purpose of this in vitro study was to measure the roughness and wear of polished, glazed, and polished then reglazed zirconia against human enamel antagonists and compare the measurements to those of veneering porcelain and natural enamel.

MATERIAL AND METHODS

Zirconia specimens were divided into polished, glazed, and polished then reglazed groups (n=8). A veneering porcelain (Ceramco3) and enamel were used as controls. The surface roughness of all pretest specimens was measured. Wear testing was performed in the newly designed Alabama wear testing device. The mesiobuccal cusps of extracted molars were standardized and used as antagonists. Three-dimensional (3D) scans of the specimens and antagonists were obtained at baseline and after 200 000 and 400 000 cycles with a profilometer. The baseline scans were superimposed on the posttesting scans to determine volumetric wear. Data were analyzed with a 1-way ANOVA and Tukey Honestly Significant Difference (HSD) post hoc tests (α=.05)

RESULTS

Surface roughness ranked in order of least rough to roughest was: polished zirconia, glazed zirconia, polished then reglazed zirconia, veneering porcelain, and enamel. For ceramic, there was no measureable loss on polished zirconia, moderate loss on the surface of enamel, and significant loss on glazed and polished then reglazed zirconia. The highest ceramic wear was exhibited by the veneering ceramic. For enamel antagonists, polished zirconia caused the least wear, and enamel caused moderate wear. Glazed and polished then reglazed zirconia showed significant opposing enamel wear, and veneering porcelain demonstrated the most.

CONCLUSIONS

Within the limitations of the study, polished zirconia is wear-friendly to the opposing tooth. Glazed zirconia causes more material and antagonist wear than polished zirconia. The surface roughness of the zirconia aided in predicting the wear of the opposing dentition.

A case-control study of dietary and erythrocyte membrane fatty acids in asthma

BACKGROUND

Epidemiological evidence suggests that increased dietary omega-6 and reduced omega-3 fatty acid intake, may have contributed to the rising prevalence of asthma, but these hypotheses have not been tested in studies comparing both dietary intake and objective measures of polyunsaturated fatty acids.

OBJECTIVE

To assess whether a higher intake of omega-6 or a lower intake of omega-3 fatty acids increases the risk of asthma, by measuring dietary fatty acid intake by a food frequency questionnaire (FFQ) and erythrocyte membrane fatty acids, as an objective biomarker of intake.

METHODS

We have compared individual fatty acid intake estimated by FFQ and by mass spectrometry of fasting erythrocyte cell membranes in 89 cases of asthma and 89 community-matched controls.

RESULTS

The odds of asthma were increased in relation to intake of the omega-3 fatty acids eicosapentaenoic acid (odds ratio (OR) for difference between the 25th and 75th centiles of intake= 1.89, 95% CI 1.15-3.11) and docosahexaenoic acid (OR = 2.11, 95% CI 1.19-3.74). There was no evidence of any difference in erythrocyte membrane levels of omega-3 fatty acids, while the odds of asthma were reduced in relation to linoleic acid (omega-6) membrane levels (OR = 0.45, 95% CI 0.21-0.95).

CONCLUSION

These findings suggest that dietary omega-3 fatty acids do not play a major role in protecting against asthma, and that higher levels of erythrocyte membrane linoleic acid are associated with a lower risk of asthma.

Amino acids and asthma: a case-control study

Amino acids contribute to various anti-oxidant and immunological activities relevant to asthma pathogenesis, raising the possibility that differences in amino acids may be involved in asthma aetiology. The authors hypothesised that cystine reduces the risk of asthma via glutathione metabolism. Methionine, glutamine, glutamic acid and glycine may have potential protective effects, whilst arginine, phenylalanine and tryptophan may have adverse effects in asthma. Fasting plasma levels of amino acids were compared in a case-control study. A total of 89 adults, aged 18-65 yrs, with asthma controlled by inhaled corticosteroids, were recruited from a volunteer database and local primary care registers, and compared with 89 controls individually matched for age, sex and primary care centre. Contrary to the primary hypothesis, cases had higher fasting plasma cystine levels than controls, and there was no difference between cases and controls in any of the other amino acids tested, with the exception of plasma glycine, which was associated with a strongly reduced risk of asthma (odds ratio for the highest tertile compared to lowest 0.30 (95% confidence interval (0.11-0.82)). This study negates the hypothesis that higher fasting plasma cystine levels have a protective effect on the risk of asthma, although the inverse correlation with plasma glycine deserves further investigation.

The relationship between vitamin D and parathyroid hormone: calcium homeostasis, bone turnover, and bone mineral density in postmenopausal women with established osteoporosis

It is evident from several studies that not all patients with hypovitaminosis D develop secondary hyperparathyroidism. What this means for bone biochemistry and bone mineral density (BMD) remains unclear. The aim of this study was to investigate the effects of hypovitaminosis D (defined as a 25OHD < or = 30 nmol/l) and patients with a blunted PTH response (defined arbitrarily as a PTH within the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) in comparison to patients with hypovitaminosis D and secondary hyperparathyroidism (defined arbitrarily as a PTH above the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) and vitamin D-replete subjects (25OHD > 30 nmol/l). Four hundred twenty-one postmenopausal women (mean age: 71.2 years) with established vertebral osteoporosis were evaluated by assessing mean serum calcium, 25OHD, 1,25(OH)2D, bone turnover markers, and BMD. The prevalence of hypovitaminosis D was 39%. Secondary hyperparathyroidism was found in only one-third of these patients who maintained calcium homeostasis at the expense of increased bone turnover relative to the vitamin D-replete subjects (bone ALP mean difference: 43.9 IU/l [95% CI: 24.8, 59.1], osteocalcin: 1.3 ng/ml [95% CI: 1.1, 2.5], free deoxypyridinoline mean difference: 2.6 nmol/nmol creatinine [95% CI: 2.5, 4.8]) and bone loss (total hip BMD mean difference: 0.11 g/cm2 [95% CI: 0.09, 0.12]). Patients with hypovitaminosis D and a blunted PTH response were characterized by a lower serum calcium (mean difference: 0.07 mmol/l [95% CI: 0.08, 0.2]), a reduction in bone turnover (bone ALP mean difference: 42.4 IU/l [95% CI: 27.8, 61.9], osteocalcin: 1.6 ng/ml [95% CI: 0.3, 3.1], free-deoxypyridinoline mean difference: 3.0 nmol/nmol creatinine [95% CI: 1.9, 5.9]), but protection in bone density (total hip BMD mean difference: 0.10 g/cm2, [95% CI: 0.08, 0.11]) as compared to those with hypovitaminosis D and secondary hyperparathyroidism. This study identifies a distinct group of patients with hypovitaminosis D and a blunted PTH response who show a disruption in calcium homeostasis but protected against PTH-mediated bone loss. This has clinical implications with respect to disease definition and may be important in deciding the optimal replacement therapy in patients with hypovitaminosis D but a blunted PTH response.

Recovery of pregnancy mediated bone loss during lactation

It is uncertain whether bone is routinely mobilised during pregnancy to provide calcium for the fetus and whether this is of a magnitude to cause osteoporosis. We have made sequential measurements of lumbar spine and hip bone mineral density (BMD) in 60 normal women before conception and then during the subsequent pregnancy out to one year after delivery. During pregnancy there was a significant fall in the BMD at the spine (1.53%), total hip (1.15%), and trochanter (3.90%) but not at the femoral neck. After delivery the women who breast-fed (n=34) showed a significant fall in BMD at all measurement sites (P<0.001) with the greatest change at the spine (4.7 +/- 3.1%) with 38% of women showing a change >5%. The women who bottle fed (n=10) increased or maintained BMD at all sites with the mixed feeders (n=16) showing an intermediate response. There was no consistent relationship between the change during pregnancy and lactation but 47% of the breast-feeders lost >5% at either the lumbar spine or trochanter. There was a good correlation between the change in BMD at these two sites (r=0.48, P<0.001). At 1 year after delivery all but 7 women had returned to within 5% of the preconceptual value at the spine and trochanter but the recovery at the total hip was less complete. Several women became transiently osteoporotic (T score below -2.5) at either spine or hip during reproduction of whom three started pregnancy with a normal BMD.

Longitudinal changes in bone mineral density during normal pregnancy

Pregnancy is a common physiological event that could affect peak bone mass and the risk of developing osteoporosis later in life. There have been few longitudinal studies over a complete reproductive cycle of any size to show whether bone mineral density (BMD) changes. We have measured BMD by dual-energy X-ray absorptiometry in 46 normal women before conception and then again immediately after delivery and compared them with 30 control women who failed to conceive. Fifteen women were osteopenic in preconceptual BMD, but there was no difference between those who did or did not become pregnant. During pregnancy there was a small and statistically nonsignificant decline in BMD at all sites. The decrease at the trochanteric region was 4.2%, while losses at other sites were about 1%. The decline at the trochanter exceeded the least significant change between two measurements (5.04%) in 17 women (40.5%) with significant changes within individuals being much less common at the other measurement sites. The nonpregnant controls showed small increases in BMD of 0.3%-1.9% but no woman lost more than the least significant change. At the trochanter there was a significant difference (P = 0.013) between those who did and did not become pregnant. There was a good correlation between changes in BMD at all sites and no significant difference in the slope of these correlations between the pregnant and control groups. Correlations with lumbar spine were total hip, r = 0.46, P = 0.0001; femoral neck, r = 0.49, P = 0.0005; and trochanter, r = 0.66, P < 0.0001.

Effect of pregnancy and obstructive jaundice on inflammatory diseases: the work of P S Hench revisited

Hench considered that cortisone improved inflammatory joint symptoms during pregnancy and obstructive jaundice. However, the improved symptoms are probably due to changes in the proportions of fatty acids in plasma and inflammatory cell phospholipids. These changes decrease the superoxide anions and eicosanoids produced and also reduce tumour necrosis factor alpha production.

Effect of low protein concentration on serum sodium measurement: pseudohypernatraemia and pseudonormonatraemia!

BACKGROUND

The effect of high concentrations of protein or lipid on the measurement of plasma sodium by indirect ion selective electrode (ISE) causing pseudohyponatraemia and pseudonormonatraemia is well described. The effect of a low total protein concentration, however, has not been described.

METHODS

In order to examine this, over a 2-week period the total protein concentration was measured on all samples received for urea and electrolyte measurement. All samples with a low (<50 g/L) or a high (> 80 g/L) total protein concentration had sodium measured by both direct and indirect ISE.

RESULTS

There were approximately equal numbers of samples with a protein concentration less than 50 g/L (1.3%) as samples with a protein concentration greater than 80 g/L (1.3%). The frequency of erroneous sodium results owing to the use of an indirect ISE was less in hypoproteinaemic (2%) than in hyperproteinaemic (20%) samples.

The anti-inflammatory effects of circulating fatty acids in obstructive jaundice: similarities with pregnancy-induced immunosuppression

Rheumatoid arthritis (RA) is ameliorated during both obstructive jaundice and pregnancy. Previous studies of polymorphonuclear leukocyte (PMN) function during pregnancy have shown reductions in the stimulated release of arachidonic acid (AA) and leukotriene B4 (LTB4), and lower NADPH oxidase activity. These changes may account for the amelioration of RA. The cause of this reduction in PMN function appears to be a progressive change in circulating fatty acids (FA), with a reduction in polyunsaturated FA, predominantly AA. The NADPH oxidase responsible for the respiratory burst has a direct requirement for polyunsaturated FA, particularly AA. We investigated whether the same changes in PMN function and FA, occur during obstructive jaundice. Patients with biliary obstructions were investigated before and after surgical correction (n=14). Obstructive jaundice caused significant changes in the proportions of serum and cellular FA. There was a striking reduction in polyunsaturated FA, particularly AA (48% in serum, p<0.001; 42% in PMNs, p<0.001) and an increase in mono-unsaturated oleic acid (24% in serum, p<0.001; 15% in PMNs, p<0.005). Similar changes occurred in mononuclear cell FA. Jaundice also caused a significant reduction in PMN function. Respiratory burst activity was reduced by between 32% and 38% in response to physiological and non-physiological stimuli, and there were similar significant reductions in the release of AA and LTB4. These changes in stimulated PMN function were evident whether or not the cells were first primed with tumour necrosis factor alpha (TNFalpha). Incubation of PMNs from healthy donors in pooled serum from patients with obstructive jaundice caused a reduction of 32% in cellular AA and 38% in NADPH oxidase activity. These findings support the idea that circulating FA can regulate PMN inflammatory responsiveness. The FA-induced attenuation in PMN activity in both jaundice and pregnancy may explain their ameliorating effects upon RA.

Measurement of urinary free cortisol using the Acs:180 serum cortisol chemiluminescent immunoassay

Measurement of urinary free cortisol using the Bayer Automated Chemiluminescent System (ACS:180 PLUS) was evaluated and compared with an in-house extraction radioimmunoassay (RIA). Inter-assay coefficients of variation were acceptable, being respectively 5.3%, 4.8% and 3.8% at 141, 406 and 942 nmol/L (n=20) for the ACS direct assay and 19.4% and 12.1% at 27 and 116 nmol/L with dichloromethane extraction (n=10). Using tritiated cortisol, mean extraction efficiency for the ACS extraction protocol was 89% compared with 104% for the RIA method (n=6, P<0.001) and using urine spiked with ACS serum calibrator, extraction efficiency was only 76% (standard deviation 8.8%, n=49) on the ACS. Urine spiked with cortisol dissolved in ethanol also gave significantly lower recoveries on the ACS for both direct and extraction methods compared with the RIA. Regression analysis of results from a mixture of control serum samples and samples from patients (n=93) showed good correlations between the direct and extraction ACS methods and the RIA extraction assay. The median concentration in 23 normal subjects and 95% reference intervals (nmol/24 h) were: ACS direct, 237 (135-505); ACS extraction, 91 (33-239); and RIA extraction, 146 (80-334). 5Beta-dihydrocortisol was the only major interferent in all assays. The ACS extraction assay showed acceptable performance and correlated well with the extraction RIA, although there was evidence of matrix-dependent effects causing low recovery.

A comparison of continuous alendronate, cyclical alendronate and cyclical etidronate with calcitriol in the treatment of postmenopausal vertebral osteoporosis: a randomized controlled trial

A number of drugs are now available for the treatment of established osteoporosis and have been shown to significantly increase bone mineral density (BMD). There are, however, few comparative treatment studies and, furthermore, adverse events remain a problem with some of the newer agents, particularly in the elderly, in everyday clinical practice. We report a 12 month, open labeled, randomized controlled, prospective treatment study in 140 postmenopausal women with established vertebral osteoporosis, comparing the effect of continuous alendronate, cyclical alendronate and cyclical etidronate with calcitriol in terms of gain in BMD, reduction in bone turnover markers and adverse event profile. The mean percentage increases in BMD at 12 months, at the spine and hip respectively, were: continuous alendronate 5.7%, 2.6%; cyclical alendronate 4.1%, 1.6%; cyclical etidronate 4.9%, 2.0% (p<0.0 1) and calcitriol 2.0%, 0.4% (NS). In comparison with calcitriol, the mean changes in BMD at the spine and hip respectively were greater in the other groups; continuous alendronate: 3.7% (95% CI 1.4 to 8.3), 2.2% (95% CI 0.7 to 4.0); cyclical alendronate: 2.1% (95% CI 1.2 to 6.4), 1.2% (95% CI -0.3 to 3.0); cyclical etidronate: 2.9% (95% CI 1.9 to 6.5), 1.6% (95% CI 0.9 to 3.1)). The reduction in bone turnover markers was between 26% and 32% in the alendronate and etidronate groups (p<0.01), with a trend toward greater reduction in the continuous alendronate group. Eight patients discontinued the study: 6 in the continuous alendronate group, 1 in the cyclical alendronate group and 1 in the calcitriol group. Two patients in the cyclical etidronate group were unable to tolerate the Cacit component, but continued on substituting Cacit with Calcichew. In summary, 12 months of treatment with continuous alendronate, cyclical alendronate and cyclical etidronate are effective in terms of the gain in BMD at the anteroposterior spine and total hip in a comparable treatment population. These treatments are more effective than calcitriol and were generally well tolerated. Continuous alendronate showed a trend toward a larger gain in BMD and greater suppression of bone turnover markers than the other treatment groups, but had a higher incidence of adverse events, particularly within the older subgroup. Cyclical alendronate offers a lower adverse event profile and appears to be effective in comparison with continuous treatment, and may possibly be an alternative in the elderly. However, further studies are necessary, but more importantly with fracture end-points.

Significance of fatty acids in pregnancy-induced immunosuppression

Pregnancy can exert suppressive effects on chronic inflammatory conditions. We have previously demonstrated a depression in polymorphonuclear leukocyte (PMN) respiratory burst during pregnancy which could explain this amelioration. To elucidate the biochemical mechanism, we have examined PMN phospholipase A2 (PLA2) activity and its relationship to cellular and circulating fatty acids in pregnant women (30 to 34 weeks) and nonpregnant controls. PMN PLA2 activity was determined by arachidonic acid (AA) and leukotriene B4 (LTB4) release, respiratory burst activity was determined by lucigenin-enhanced chemiluminescence, and total serum and PMN fatty acid levels were determined by gas-liquid chromatography. AA release was significantly reduced for pregnancy PMNs in response to N-formyl-met-leu-phe (fMLP) under unprimed and tumor necrosis factor alpha (TNF-alpha)- or interleukin 8-primed conditions. Similarly, LTB4 liberation was significantly reduced in response to fMLP and phorbol myristate acetate in unprimed and TNF-alpha-primed pregnancy PMNs. All major fatty acid classes were altered in the pregnant state. Of these differences in PMNs, oleic acid and alpha-linolenic acid showed a significant increase (13 and 26%, respectively) and stearic acid and AA showed a significant decrease (8 and 30%, respectively). The stearic acid, oleic acid, and AA compositions of all cells analyzed correlated with their corresponding changes in serum fatty acid levels. Crossover serum incubations modified both fatty acid profiles and the PMN respiratory burst accordingly, while individual fatty acid incorporation studies highlighted the importance of polyunsaturated fatty acids for NADPH oxidase efficiency. These findings indicate that the attenuation of PMN function in pregnancy may originate from a reduction in the available pool of cellular fatty acids. Furthermore, this reduction arises as a direct result of a pregnancy-induced shift in circulating fatty acids from polyunsaturated to monounsaturated forms.

The effect of different dietary fatty acids on lipoprotein metabolism: concentration-dependent effects of diets enriched in oleic, myristic, palmitic and stearic acids

While it is well established that the fatty acid composition of dietary fat is important in determining plasma lipoprotein cholesterol concentrations, the effects of changing the absolute quantities of the individual fatty acids are less clear. In the present study Golden Syrian hamsters were fed on isoenergetic, low cholesterol (0.05 g/kg) diets containing 100, 150 or 200 g added fat/kg. This consisted of triolein (TO) alone, or equal proportions of TO and either trimyristin (TM), tripalmitin (TP) or tristearin (TS). Each trial also included a control group fed on a diet containing 50 g TO/kg. As the mass of TO in the diet increased, plasma VLDL-cholesterol concentrations rose. The TM-rich diets produced a concentration-dependent increase in total plasma cholesterol which was a result of significant increases in both VLDL and HDL levels. The TP-rich diets increased plasma LDL- and HDL-cholesterol levels in a concentration-dependent manner. TS-containing diets did not increase the cholesterol content of any of the major lipoprotein fractions. Hepatic LDL-receptor mRNA concentrations were significantly decreased in animals fed on TP, while apolipoprotein B mRNA concentrations were significantly increased. Thus, on a low-cholesterol diet, increasing the absolute amount of dietary palmitic acid increases LDL-cholesterol more than either myristic or stearic acid. These effects on lipoprotein metabolism may be exerted through specific modulation of the expression of the LDL receptor and apolipoprotein B genes.

Laboratory studies in cross-species lung transplantation

The lack of sufficient suitable human donor lungs for the many patients requiring pulmonary transplantation as life-saving therapy for end-stage lung diseases has generated extensive interest in cross-species lung transplantation. Ethical concerns and those of animal rights advocates have prompted studies of nonprimate species as potential solid organ donors for humans. This paper provides an overview of some of the laboratory studies of cross-species pulmonary transplantation performed over the past 20 years and focuses, in particular, on more recent work (from our laboratory and others) in the area of porcine-to-primate pulmonary xenotransplantation.

Pituitary dysfunction in recently post-menopausal women. Nottingham EPIC Study Group

OBJECTIVE

Some recently post-menopausal women have lower than expected FSH concentrations, raising the possibility of subclinical hypothalamo-pituitary impairment. We have therefore performed pituitary stimulation tests in a group of recently post-menopausal women recruited to a bone loss prevention study.

DESIGN

Prospective study of health volunteers.

SETTING

Outpatient, teaching hospital in Nottingham UK.

SUBJECTS

Forty-seven women selected from a cohort of 428 healthy volunteers to an osteoporosis prevention study all within 10 years of the menopause.

MAIN OUTCOME MEASURES

Response of the pituitary to formal stimulation tests and its relationship to bone mineral density.

RESULTS

A significantly attenuated response to pituitary stimulation was found in a group of otherwise healthy women with an FSH considered to be inappropriately low for the level of circulating oestradiol. The impaired responses were significant not only for FSH as expected but also to LH and prolactin at 1 hour after injection of GnRH and TRH (area under the curve, FSH P = 0.01, LH P = 0.001, prolactin P < 0.0001). TSH secretion was not significantly impaired. Baseline cortisol, growth hormone and thyroxine (T4) were normal in both control and test subjects. The test group was both heavier and taller, with a higher lean body mass, a higher body mass index and a greater total body fat than the controls. Bone mineral density showed no significant differences between the groups. Test subjects also had a higher free oestradiol index (P < 0.001) which correlated strongly (r = 0.534, P = 0.00026) with baseline FSH levels and possibly reflects a greater tissue exposure to biologically active hormone. Oestrone concentrations were, however, no different between the groups.

CONCLUSIONS

Serum FSH concentrations are not invariably elevated in recently post-menopausal women and use of FSH as a determinant for postmenopausal status in clinical trials should be used with caution. Notwithstanding their higher free oestradiol index, women found to have an abnormally low basal FSH had evidence of poor prolactin, FSH and LH but not TSH responses to pituitary stimulation. This may represent either a degree of subclinical pituitary failure of a variant of normal. The low levels of gonadotrophin activity did not affect bone mineral density.

Control of late neutrophil-specific gene expression: insights into regulation of myeloid differentiation

During myeloid differentiation, the pluripotent hematopoietic stem cell passes through several well-defined morphologic stages within the bone marrow. These changes include progressive nuclear segmentation and the acquisition of stage-specific granules. Primary granules appear at the myeloblast stage, and are found in both neutrophils and monocytes. At the myelocyte stage, neutrophil precursors acquire specific granules, a marker of commitment to terminal neutrophil differentiation. This complex developmental pathway is just beginning to be elucidated. Current evidence suggests that myeloid differentiation is regulated primarily by transcriptional regulatory proteins, and that dysfunction of those regulators is involved in most disorders of neutrophil maturation. Furthermore, there is evidence that study of late gene expression may provide insights into more proximal events in granulocytic maturation. In this review, we provide a brief overview of myeloid differentiation with emphasis on the culture systems available for the study of granulopoiesis and the insights they provide into the regulation of late neutrophil-specific gene expression. We discuss the relevance of these observations to our understanding of the pathogenesis of defects in neutrophil differentiation.

Phase I and pharmacokinetic study of tirapazamine (SR 4233) administered every three weeks

Tirapazamine (SR 4233; 3-amino-1,2,4-benzotriazine-1,4-di-N-oxide) is a bioreductive agent exhibiting up to 200 x greater toxicity for hypoxic cells as compared to oxygenated cells. In murine studies, a selective increase in tumor kill was observed when tirapazamine was coadministered with other agents, notably cisplatin. A Phase I study of single-agent tirapazamine administered i.v. every 3 weeks was conducted to determine the toxicity of a schedule for use with systemic chemotherapy. A total of 28 patients were given 50 courses of tirapazamine at doses ranging from 36-450 mg/m2. No tumor responses were observed. Reversible deafness and tinnitus were dose-limiting, with ototoxicity observed in 1 of 6 patients treated at 330 mg/m2, 1 of 4 patients treated at 390 mg/m2, and 3 of 3 patients treated at 450 mg/m2. Muscle cramps, nausea, and vomiting were also observed. Pharmacokinetic studies revealed a greater than dose-proportional increase in the area under the plasma concentration x time curve (AUCs) of the two major metabolites. Patients who developed ototoxicity generally showed higher plasma AUC values for the parent drug and metabolites. The mean plasma tirapazamine AUC at 330 mg/m2 was 1026.5 microgram/ml x min (range 863. 8-1252.3), but no pharmacokinetic data are available for the solitary patient who developed otoxicity at this dose level. These AUC values were in the (estimated) range required for therapeutic effect in murine studies. Ototoxicity was not observed when the AUC of tirapazamine was equal to or less than 1252 microgram/ml x min. The dose of 330 mg/m2 was therefore chosen as an appropriate level for combination chemotherapy studies.

Fecal alpha 1-antitrypsin detection of colorectal neoplasia. An evaluation using HemoQuant

Fecal alpha 1-antitrypsin measurement may be of value for the detection of colorectal neoplasia and is compared with the HemoQuant test in 119 subjects with either a screen-positive Hemoccult result (N = 78) or iron-deficiency anaemia (N = 41). Nineteen patients were found to have colorectal cancer, 35 had colorectal adenomatous polyps, 5 had inflammatory bowel disease, and 60 had no detected cause of occult blood loss. Of the cancer patients, 63% (12/19) were detected by fecal alpha 1-antitrypsin and 63% (12/19) by HemoQuant. Of the adenomas > 1 cm in diameter 33% (7/23) were detected by fecal alpha 1-antitrypsin and 26% (6/23) by HemoQuant. There was a poor correlation between fecal alpha 1-antitrypsin and HemoQuant results for colorectal cancers (r = 0.37, P > 0.05), and combining the tests, the sensitivity for colorectal cancer was increased to 84% (16/19). Fecal protein loss, as measured using alpha 1-antitrypsin, appears to involve largely different mechanisms from that of blood loss from colorectal cancers.

Modulation of hepatic apolipoprotein B, 3-hydroxy-3-methylglutaryl-CoA reductase and low-density lipoprotein receptor mRNA and plasma lipoprotein concentrations by defined dietary fats. Comparison of trimyristin, tripalmitin, tristearin and triolein

Different dietary fatty acids exert specific effects on plasma lipids but the mechanism by which this occurs is unknown. Hamsters were fed on low-cholesterol diets containing triacylglycerols enriched in specific saturated fatty acids, and effects on plasma lipids and the expression of genes involved in hepatic lipoprotein metabolism were measured. Trimyristin and tripalmitin caused significant rises in low-density lipoprotein (LDL) cholesterol which were accompanied by significant reductions in hepatic LDL receptor mRNA levels. Tripalmitin also increased hepatic expression of the apolipoprotein B gene, implying an increased production of LDL via very-low-density lipoprotein (VLDL) and decreased removal of LDL in animals fed this fat. Hepatic levels of 3-hydroxy-3-methylglutaryl-CoA reductase mRNA did not vary significantly between the groups. Compared with triolein, tristearin had little effect on hepatic gene expression or total plasma cholesterol. However, it caused a marked decrease in VLDL cholesterol and a rise in LDL cholesterol such that overall it appeared to be neutral. Lipid analysis suggested a rapid desaturation of much of the dietary stearate. The differential changes in plasma lipids and hepatic mRNA levels induced by specific dietary fats suggests a role for fatty acids or a metabolite thereof in the regulation of the expression of genes involved in lipoprotein metabolism.

The information and learning needs of the caregiving family of the adult patient with cancer

The need for information by the caregiving family of an adult patient with cancer has been identified by research. This paper is a literature review of the information and learning needs of caregiving relatives. By meeting these needs the health care professional is able to help support the family, and therefore the patient, with the difficult adjustment to the diagnosis and through the subsequent course of the disease. The health care professional facilitates the individual caregivers' coping mechanisms and the benefits can be seen in the caregiving outcome for both the family and the patient. Information needs vary from individual to individual and are dynamic throughout the cancer experience. This paper describes the role of the nurse in this area, and encourages the nurse to act as a resource person for the caregiver by the appropriate delivery of information and by ensuring that the information given to the family by other health care professionals is understood and fulfils their needs.

Assessment of retinol-binding protein excretion in normal children

Retinol-binding protein (RBP) is a low molecular weight protein freely filtered at the glomerulus. The fractional tubular reabsorption of RBP is 99.97% and increased excretion is therefore a sensitive marker of tubular dysfunction. We obtained early-morning urine specimens from 151 well children, from newborn to 16 years of age. RBP was measured using an enzyme-linked immunosorbent assay, albumin by a radioimmunoassay and creatinine by a modified Jaffé reaction. Protein excretion was assessed by calculating the protein:creatinine ratio for early-morning urine samples. We found a fall in both RBP and albumin excretion with increasing age, particularly in the 1st year of life, with a much wider variation in values from the infants studied. The mean excretion of RBP for children aged 0-6 months [51.4 (0.6-4,719) micrograms/mmol] was significantly higher (P < 0.001) than the mean for children aged 6 months to 16-years [15.0 (3.8-60) micrograms/mmol]. It has been shown that measurement of tubular proteinuria using the RBP: creatinine ratio is useful in the assessment of children with renal disease and we propose a value two standard deviations above the geometric mean for the age of the patient as an upper limit of normal.

Value of faecal alpha-1-antitrypsin, haemoglobin and a chemical occult blood test in the detection of gastrointestinal disease

Specimens from hospital out-patients and in-patients sent for faecal occult blood tests were also analysed for faecal alpha-1-antitrypsin and faecal haemoglobin. 453 stool specimens from 222 patients were analysed. The clinicians were only aware of the faecal occult blood test results, and diagnoses were made using conventional clinical and investigative criteria. Gastrointestinal bleeding or putative sites of bleeding were diagnosed in 98 patients, whereas in 81 patients putative sites of bleeding were not found or other cause of anaemia diagnosed. In 41 patients there was insufficient information to reach a definitive diagnosis. Comparison of the 3 faecal tests using these grouping methods showed that faecal alpha-1-antitrypsin performed best, with an accuracy of 89%, specificity of 90% and sensitivity of 88%, all significantly better (P < 0.001) than the faecal occult blood test (68%, 60% and 73%, respectively). There was no significant difference between the performance of the faecal occult blood and faecal haemoglobin tests. Faecal alpha-1-antitrypsin measurement may be a useful investigation in situations where a faecal occult blood test would normally be requested.

Placebo-controlled trial of lisinopril in normotensive diabetic patients with incipient nephropathy

To study the effects of an angiotensin converting enzyme inhibitor, lisinopril, on renal function in incipient diabetic nephropathy, a prospective double-blind randomised placebo-controlled single centre study was set up at our outpatient diabetic-renal clinic. There were 27 patients with Type I and Type II diabetes with an albumin excretion rate of between 20 micrograms/min and 200 micrograms/min, respectively and no hypertension. Intervention treatment with placebo or low dose lisinopril was for 48 weeks. The main outcome changes were in urinary albumin excretion rate, urinary prostaglandin excretion, and glomerular filtration rate. Secondary outcome measures included changes in BP and heart rate. Of the 32 patients entered into the study, 27 completed 48 weeks treatment (12 lisinopril, 15 placebo). Mean (+/- SD) urinary albumin excretion rate fell from 57.6 (25.7) micrograms/min (n = 15) at visit 1 to 26.8 (26.7) micrograms/min (n = 12) at visit 7 after 48 weeks treatment in the lisinopril group but not in the placebo group: 119.2 (116.6) micrograms/min (n = 17) vs. 113.7 (77.0) micrograms/min (n = 15). There was a least squares mean treatment difference of -67.6 micrograms/min (95% confidence interval (CI), -115.0 to -20.2, P < 0.01) in favour of lisinopril compared with placebo. After 48 weeks treatment seven lisinopril treated patients were normoalbuminuric and five were microproteinuric; three placebo treated patients were normoalbuminuric, nine were microalbuminuric and three were macroproteinuric. Excretion of prostaglandin-F1 alpha (PGF1 alpha) and thromboxane-B2 (TXB2) fell in the lisinopril treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effects of an angiotensin converting enzyme inhibitor and a calcium antagonist in hypertensive, macroproteinuric diabetic patients: a randomised double-blind study

The objective of this study was to compare the effects of an angiotensin converting enzyme inhibitor, lisinopril, with those of a calcium blocker, nifedipine, on BP control and renal function, in a prospective randomised double-blind, double-dummy trial lasting 19 weeks in patients with diabetic nephropathy. We enrolled 28 diabetic patients with hypertension and macroproteinuria from the out-patient diabetic-renal clinic. The antihypertensive treatment consisted of lisinopril or nifedipine, and their effect on arterial BP, urinary albumin excretion, glomerular filtration rate, and renal blood flow were measured. BPs at entry were 166/99 (SD 23/9) mmHg for the lisinopril group and 165/99(21/7) mmHg for the nifedipine group. BPs fell to 143/88 (17/13) mmHg for the lisinopril group and 148/85(25/10) mmHg for the nifedipine group at the end of the study. The albumin excretion rate fell in the lisinopril group from 738.7 (635.2) micrograms/min to 644.6 (965.2) micrograms/min and rose in the nifedipine group from 981.2 (1022.2) micrograms/min to 1072.5 (908.5) micrograms/min (P = NS). Glomerular filtration rates fell from 105.2 (57.5) ml/min per 1.73 m2 to 72.1 (39.4) ml/min per 1.73 m2 in the lisinopril group and from 109.9 (50.0) ml/min per 1.73 m2 to 82.9 (53.9) ml/min per 1.73 m2 in the nifedipine treated group. Renal blood flow fell from 446.8 (217.9) ml/min per 1.73 m2 to 435.1 (243.3) ml/min per 1.73 m2 for the lisinopril group and from 473.0 (216.4) ml/min per 1.73 m2 to 419.0 (278.6) ml/min per 1.73 m2 for the nifedipine group. Differences between the groups were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocyte beta adrenoceptor upregulation and improved cardiac response to adrenergic stimulation following converting enzyme inhibition in congestive heart failure

To determine the effect of ACE inhibitor therapy on lymphocyte beta-adrenoceptor function and density, as well as the in vivo myocardial response to beta-agonist stimulation, we studied 12 patients with chronic severe heart failure before and after 16 weeks' treatment with quinapril. Lymphocyte beta-adrenoceptor function (intracellular cAMP production in response to isoprenaline) was studied as a surrogate tissue for myocardium, and increased significantly after quinapril at concentrations of isoprenaline between 10(-3) and 50 mmol.l-1. Lymphocyte beta-adrenoceptor density (six patients) measured by [125I] iodocyanopindolol binding, increased from 242 +/- 72 (mean +/- SEM) to 884 +/- 17 receptors/cell (P < 0.05). Changes in functional myocardial beta-adrenoceptor status were determined by measuring changes in haemodynamic responses to exercise and to incremental dobutamine infusion. Following quinapril there were significant improvements in cardiac index, stroke volume and cardiac power output during sub-maximal exercise testing and dobutamine infusion; stroke work index in response to dobutamine (but not exercise) improved significantly. ACE inhibitors cause lymphocyte beta-adrenoceptor upregulation in heart failure, which is associated with an improved cardiac pumping capacity in response to beta-agonist stimulation.

Platelet behaviour and haemostatic variables in type 1 (insulin-dependent) diabetic patients with and without albuminuria

Abnormalities of haemostasis have been implicated in the development of both large and small vessel disease in diabetes. Platelet behaviour and coagulation factors were studied in 28 non-diabetic control subjects and 81 Type 1 diabetic patients with different degrees of albuminuria. Twenty-four (30%) patients had macro- or micro-albuminuria. These patients had elevated levels of beta-thromboglobulin compared with normo-albuminuric patients and control subjects (macro-albuminuric 113 (range 60-314), micro-albuminuric 88 (50-220), normo-albuminuric 55 (13-273), control 52 (18-210) micrograms l-1, p less than 0.001). Similar results were found for platelet factor 4 (macro-albuminuric 57 (9-350), micro-albuminuric 78 (12-205), normo-albuminuric 10 (2-135), control 9 (3-95) micrograms l-1, p less than 0.001). There were decreased beta-thromboglobulin:platelet factor 4 ratios in the albuminuric patients compared with control subjects and normo-albuminuric patients (p less than 0.001). There is abnormal platelet activity in Type 1 diabetic patients with elevated albumin excretion rates.

Creatine kinase activity in patients with brittle asthma treated with long term subcutaneous terbutaline

Infused beta 2 agonists have been shown to cause focal myocardial necrosis. Serum creatine kinase activity was compared in 13 patients with brittle asthma currently being treated with subcutaneous terbutaline and an age and sex matched control group of patients with moderate asthma having inhaled treatment only. The median serum total creatine kinase activity for patients receiving subcutaneous terbutaline (211 units/l) was greater than that for the control group (120 units/l). The cardiac specific isoenzyme component of creatine kinase was not raised in either group, and the electrocardiograms and serum aspartate aminotransferase activity were normal. Electromyograms in five patients receiving subcutaneous terbutaline with high creatine kinase activity showed changes consistent with myositis in two, one of whom was subsequently shown to have a metabolic myopathy, which is thought to be long standing. No pathological changes were seen in the myocardium at necropsy in a patient who died from an acute attack of asthma while taking subcutaneous terbutaline. These results suggest that the raised creatine kinase activity seen in patients receiving this treatment is unlikely to be myocardial in origin.