P10.02 Combined methods of a micropump system and a chronic cranial window allows tumor observation with multi photon laser scanning microscopy under continuous treatment

BACKGROUND

Glioblastomas are notoriously therapy resistant tumors. As opposed to other tumor entities, no major advances in therapeutic success have been made in the past decades. This has been calling for a deeper biological understanding of the tumor, its growth and resistance patterns. We have been using a xenograft glioma model, where human glioblastoma cells are implanted under chronic cranial windows and studied longitudinally over many weeks and months using multi photon laser scanning microscopy (MPLSM). To test the effect of (new) drugs, a stable and direct delivery system avoiding the blood-brain-barrier has come into our interest.

MATERIAL AND METHODS

We implanted cranial windows and fluorescently labeled human glioblastoma stem-like cells into NMRI nude mice to follow up on the tumor development in our MPLSM model. After tumor establishment, an Alzet® micropump was implanted to directly deliver agents via a catheter system continuously over 28 days directly under the cranial window onto the brain surface. Using the MPLSM technique, the continuous delivery and infusion of drugs onto the brain and into the tumor was measured over many weeks in detail using MPLSM.

RESULTS

The establishment of the combined methods allowed reliable concurrent drug delivery over 28 days bypassing the blood-brain-barrier. Individual regions and tumor cells could be measured and followed up before, and after the beginning of the treatment, as well as after the end of the pump activity. Fluorescently labelled drugs were detectable in the MPLSM and its distribution into the brain parenchyma could be quantified. After the end of the micropump activity, further MPLSM measurements offer the possibility to observe long term effects of the applied drug on the tumor.

CONCLUSION

The combination of tumor observation in the MPSLM and concurrent continuous drug delivery is a feasible and reliable method for the investigation of (novel) anti-tumor agents, especially drugs that are not blood-brain-barrier penetrant. Morphological or even functional changes of individual tumor cells can be measured under and after treatment. These techniques can be used to test new drugs targeting the tumor, its tumor microtubes and tumor cells networks, and measure the effects longitudinally.

Safety in magnetic resonance units: an update

The number of anaesthetists who are involved in magnetic resonance (MR) units is increasing. Magnetic resonance systems are becoming more powerful and interventional procedures are now possible. This paper updates information relating to safety terminology, occupational exposure, reactions to gadolinium-based contrast agents and the risk of nephrogenic systemic fibrosis. Magnetic resonance examinations of patients with pacemakers are still generally contra-indicated but have been carried out in specialist centres under strictly controlled conditions. As availability of MR increases, so the education of anaesthetists, who are occasionally required to provide a service, must be considered.

Anaesthesia in MR units was first described in the 1980s. Guidelines on the provision of anaesthetic services in MR units were published by the Association of Anaesthetists of Great Britain and Ireland (AAGBI) in 2002 [1]. Since then, the number of hospitals with MR units, and hence the number of patients requiring anaesthesia for MR, has increased. While the issues relating to setting up anaesthetic services in MR have not changed, there have been a number of developments that warrant this update:

Safety terminology and guidelines have changed.

MR systems utilise higher magnetic-field strengths and more open designs are available.

Interventional and intra-operative MR are now routine in some centres.

Mobile MR scanners are increasingly used to reduce waiting lists.

Although still generally contra-indicated, some patients with pacemakers have been scanned under strictly controlled conditions in specialist centres.

‘MR safe’ medical implants are now being produced.

New equipment is now available for use in MR.

Out-of-hours availability of MR investigations has increased.

Reports of allergic reactions to MR contrast media have increased.

Gadolinium based contrast agents (Gd-CAs) are associated with a varying degree of risk of nephrogenic systemic fibrosis in patients with impaired renal function.

Impact of model perfumes on surfactant and mixed surfactant self-assembly

The impact of some model perfumes on surfactant self-assembly has been investigated, using small-angle neutron scattering. A range of different model perfumes, with differing degrees of hydrophilicity/hydrophobicity, have been explored, and in order of increasing hydrophobicity include phenyl ethanol (PE), rose oxide (RO), limonene (LM), linalool (LL), and dihydrogen mercenol (DHM). The effect of their solubilization on the nonionic surfactant micelles of dodecaethylene monododecyl ether (C12EO12) and on the mixed surfactant aggregates of C12EO12 and the cationic dialkyl chain surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) has been quantified. For PE and LL the effect of their solubilization on the micelle, mixed micelle/lamellar and lamellar regimes of the C12EO12/DHDAB mixtures, has also been determined. For the C12EO12 and mixed DHDAB/C12EO12 micelles PE is solubilized predominantly at the hydrophilic/hydrophobic interface, whereas the more hydrophobic perfumes, from RO to DHM, are solubilized predominantly in the hydrophobic core of the micelles. For the C12EO12 micelles, with increasing perfume concentration, the more hydrophobic perfumes (RO to DHM) promote micellar growth. Relatively modest growth is observed for RO and LM, whereas substantial growth is observed for LL and DHM. In contrast, for the addition of PE the C12EO12 micelles remain as relatively small globular micelles, with no significant growth. For the C12EO12/DHDAB mixed micelles, the pattern of behavior with the addition of perfume is broadly similar, except that the micellar growth with increasing perfume concentration for the more hydrophobic perfumes is less pronounced. In the Lbeta (Lv) region of the DHDAB-rich C12EO12/DHDAB phase diagram, the addition of PE results in a less structured (less rigid) lamellar phase, and ultimately a shift toward a structure more consistent with a sponge or bicontinuous phase. In the mixed L1/Lbeta region of the phase diagram PE induces a slight shift in the coexistence from Lbeta toward L1. The addition of LL to the Lbeta (Lv) region of the DHDAB-rich C12EO12/DHDAB phase diagram also results in a reduction in the lamellar structure (less rigid lamellae), and a shift toward a structure more consistent with a sponge or bicontinuous phase, or a coexisting phase of small vesicles. For the mixed L1/Lbeta region of the phase diagram LL induces a shift toward a greater L beta component.

Tissue-engineered bone biomimetic to regenerate calvarial critical-sized defects in athymic rats

A tissue-engineered bone biomimetic device was developed to regenerate calvaria critical-sized defects (CSDs) in athymic rats. Well-documented evidence clearly confirms that left untreated, CSDs will not spontaneously regenerate bone. To accomplish regeneration, four candidate treatments were assessed: porous poly(D,L-lactide) and type I collagen (PLC), PLC and human osteoblast precursor cells (OPCs) at 2 x 10(5) (PLC/OPCs), PLC and 50 microg of recombinant human bone morphogenetic protein-2 (PLC/rhBMP-2), and PLC/OPCs/rhBMP-2 (the bone biomimetic device). The hypotheses for this study were PLC/OPCs/rhBMP-2 would promote more new bone formation in CSDs than the other treatments and the amount of bone formation would be time dependent. To test the hypotheses, outcomes from treatments were measured at 2 and 4 weeks postoperatively by radiomorphometry for percent radiopacity and by histomorphometry for square millimeters of new bone formation. Data were analyzed by analysis of variance and Fisher's protected least significant difference for multiple comparisons with p < or = 0.05. At 2 and 4 weeks, radiomorphometric data revealed PLC/rhBMP-2 and PLC/OPCs/rhBMP-2 promoted significantly more radiopacity than either PLC or PLC/OPCs. Histomorphometry data at 2 and 4 weeks indicated significantly more new bone formation for PLC/rhBMP-2, PLC/OPCs/rhBMP-2, and PLC/OPCs compared to PLC. By 4 weeks, PLC/OPCs/rhBMP-2 and PLC/rhBMP-2 had regenerated the CSDs with more new bone than the other treatments; the quantity of bone at 4 weeks for these treatments was greater than at 2 weeks.

Effects of methyltestosterone on insulin secretion and sensitivity in women

The frequent coexistence of hyperandrogenism and insulin resistance is well established; however, whether a cause and effect relationship exists remains to be established. In this study we tested the hypothesis that short-term androgen administered to women would induce insulin resistance. To test this hypothesis, regularly menstruating, nonobese women were studied before and during methyltestosterone administration (5 mg tid for 10-12 days) by the hyperglycemic (n=8) and euglycemic, hyperinsulinemic (n=7) clamp techniques. Short-term methyltestosterone administration had no significant effects on the fasting levels of glucose, insulin, c-peptide, glucagon, or glucose turnover. During the hyperglycemic clamp studies, the mean glucose level during the final hour was 203+/-2 and 201+/-1 mg/dL in the methyltestosterone and control studies, respectively. The insulin response to this hyperglycemic challenge was slightly but not significantly greater during methyltestosterone treatment (first phase 59+/-8 vs. 50+/-8 microU/mL in controls; second phase 74+/-9 vs. 67+/-9 microU/mL in controls; total insulin response 133+/-16 vs. 117+/-15 microU/mL in controls). In spite of this, glucose uptake was reduced from the control study value of 10.96+/-1.11 to 7.3+/-0.70 mg/kg/min by methyltestosterone (P < 0.05). The ratio of glucose uptake per unit of insulin was also significantly reduced from a control study value of 14.3+/-1.4 to 9.4+/-1.3 mg/kg/min per microU/mL x 100 during methyltestosterone administration. In the euglycemic hyperinsulinemic clamp studies, insulin was infused at rates of 0.25 and 1.0 mU/kg/min to achieve insulin levels of approximately 25 and 68 microU/mL, respectively. During low-dose insulin infusion, rates of endogenous hepatic glucose production were equivalently suppressed from basal values of 2.37+/-0.29 and 2.40+/-0.27 mg/kg/min to 0.88+/-0.25 and 0.77+/-0.26 mg/kg/min in the methyltestesterone and control studies respectively. Whole body glucose uptake during low-dose insulin infusion was minimally affected. During the high-dose insulin infusion, endogenous hepatic glucose production was nearly totally suppressed in both groups. However, whole body glucose uptake was reduced from the control value of 6.11+/-0.49 mg/kg/min to 4.93+/-0.44 mg/kg/min during methyltestosterone administration (P < 0.05). Our data demonstrate that androgen excess leads to the development of insulin resistance during both hyperglycemic and euglycemic hyperinsulinemia. These findings provide direct evidence for a relationship between hyperandrogenemia and insulin resistance, and its associated risk factors for cardiovascular disease.

Economic evaluation of insulin lispro versus neutral (regular) insulin therapy using a willingness-to-pay approach

This willingness-to-pay (WTP) analysis is the first study of its kind undertaken in Australia to support an application for listing of a new drug on the Australian national formulary. The technique offers the advantage of being able to summarise diverse outcomes of therapy in a single unit of measure. Willingness to pay is used to value benefits in cost-benefit analysis (CBA), and CBA represents an absolute decision rule. An open-ended question with a bid-up approach was used to minimise bias and elicit the maximum amount patients would be willing to pay for insulin lispro. The WTP study incorporated scenarios describing the outcomes from insulin lispro and neutral (regular) insulin, the results from a formal metaanalysis and a description of the injection characteristics of the therapies. A sample of 83 patients with type I or II diabetes mellitus were surveyed using an open questionnaire to determine their maximum willingness to pay for the therapy they preferred. Overall, 92% of patients preferred insulin lispro (referred to as insulin A) and 8% preferred neutral insulin (referred to as insulin B). The incremental benefit per patient was calculated as 452.16 Australian dollars ($A) per year. Insulin lispro was listed on the Australian national formulary at a 36% premium over neutral insulin, so the additional cost per patient would be $A70.32 per year. Therefore, costs were exceeded by the benefits and insulin lispro was deemed to offer a net benefit. A multivariate analysis indicated that those patients who were middle-aged had the strongest preference for insulin lispro.

Clinical outcomes with insulin lispro compared with human regular insulin: a meta-analysis

We performed a meta-analysis to compare insulin lispro and human regular insulin across a range of outcomes common in modern diabetes management to establish a basis for subsequent economic evaluation. We included all identifiable head-to-head randomized controlled trials, pooling dichotomous and continuous outcomes using appropriate statistical methods. Measures associated with various aspects of glycemic control (preparandial and postprandial glycemic control, glucose excursion, and glycated hemoglobin) and with hypoglycemia were evaluated. Results showed significant differences in favor of insulin lispro in the outcomes associated with postprandial glycemic control without an increase in hypoglycemia. Outcomes associated with fasting glycemic control and overall long-term glycemic control were not significantly different between insulin lispro and human regular insulin. Alternative approaches to the meta-analysis were explored but did not alter the conclusions. Thus our meta-analysis supports the existence of significant differences between insulin lispro and human regular insulin in terms of important postprandial outcome measures in diabetes. In addition, there is a practical difference in injection timing relative to meals: human regular insulin should be administered 30 to 45 minutes before eating, whereas insulin lispro can be administered 15 minutes or less before eating. These differences should be the subject of an economic evaluation to assist in determining the place of insulin lispro in diabetes management.

Distribution of platelet-derived growth factor (PDGF) A chain mRNA, protein, and PDGF-alpha receptor in rapidly forming human bone

Platelet-derived growth factors (PDGFs) are potent bone cell mitogens which stimulate the proliferation of osteoblastic cells, may also be involved in the regulation of osteoclastic bone resorption, and indirectly induce vascular endothelial cell proliferation and angiogenesis. In view of the established relationship between angiogenesis and osteogenesis, the production of PDGFs by both osteoblastic and vascular endothelial cells suggests that they may play a role in bone formation during skeletal development. We have used two human models of rapid bone formation, heterotopic bone and osteophytic bone, to investigate the expression of PDGF-A mRNA and protein and the PDGF-alpha receptor protein in vivo using in situ hybridization and immunohistochemistry. PDGF-A mRNA and protein were widely distributed throughout heterotopic and osteophytic bone. Within the cartilaginous tissue PDGF-A mRNA and protein were most strongly expressed by mature chondrocytes with decreased expression in the hypertrophic zone and almost no staining in the mineralizing and mineralized zones. PDGF mRNA and protein were also expressed in cells of small blood vessels within fibrous and cartilaginous tissue. In contrast, PDGF-alpha receptor expression was restricted to a minority of hypertrophic chondrocytes and sites of vascular invasion. Within the bone and fibrous tissue the growth factor and the receptor were widely distributed, being detected on most cells at sites of bone formation or in remodeling sites; no receptor was detected on osteoclasts. These data demonstrate the widespread expression of PDGF-A and its receptor in forming human bone and indicate that this growth factor may exert autocrine and paracrine effects to regulate osteogenesis during skeletal development.

Progesterone administration induced impairment of insulin suppression of hepatic glucose production

OBJECTIVE

To assess whether P administration impairs insulin-mediated glucose uptake.

DESIGN

Two-step euglycemic hyperinsulinemic clamp studies.

SETTING

Rats studied with (n = 11) or without (n = 10) P treatment.

PARTICIPANTS

Conscious, unstressed, oophorectomized female rats.

MAIN OUTCOME MEASURES

Plasma glucose and insulin levels and the rates of glucose turnover results.

RESULTS

Fasting glucose (115 +/- 5 versus 109 +/- 4 mg/dL; conversion factor to SI units 0.05551) and insulin (1.67 +/- 0.24 versus 1.51 +/- 0.22 ng/mL; conversion factor to SI units 174.5) levels were not significantly different in the control and P treated groups, respectively. However, the basal rate of glucose turnover was significantly higher in P-treated rats (8.38 +/- 0.50 versus 6.59 +/- 0.35 mg/kg per minute in controls. During low-dose insulin infusion (2 mU/kg per minute), there was no difference in glucose or insulin levels, or the rate of glucose utilization; however, residual hepatic glucose production was significantly greater in the P group (5.34 +/- 0.68 versus 2.57 +/- 1.00 mg/kg per minute) in controls. At high-dose insulin infusion (10 mU/kg per minute), hepatic glucose production was completely suppressed in both groups; there was no difference in insulin sensitivity as assessed by the glucose utilization rate or the ratio of glucose uptake to insulin level.

CONCLUSIONS

Chronic P therapy does not alter insulin-mediated glucose utilization in peripheral tissues but does reduce the ability of insulin to suppress endogenous hepatic glucose production.

Influence of basal androgen levels in euandrogenic women on glucose homeostasis

OBJECTIVE

To evaluate possible relationships between insulin action and the normal variations of serum androgens in euandrogenic women.

DESIGN

Prospective evaluation of insulin action in normal nonobese women using hyperglycemic and euglycemic hyperinsulinemic clamp techniques, correlating insulin action to serum testosterone (T), free T, androstenedione (A), and dehydroepiandrosterone sulfate (DHEAS). Statistical analysis used Spearman's rank correlation.

SETTING

Yale University Clinical Research Center.

PARTICIPANTS

Nonobese females with normal oral glucose tolerance tests, on no medications known to affect glucose metabolism, having the following range of serum androgen levels: T, 0.69 to 3.12 nmol/L; free T, 0.17 to 1.25 nmol/L; A, 2.48 to 11.31 nmol/L; DHEAS, 0.68 to 10.61 mumol/L. Total number of patients studied: hyperglycemic clamps, n = 58; euglycemic hyperinsulinemic clamps, n = 43.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Pancreatic insulin secretion in response to hyperglycemia and insulin action as assessed by insulin-mediated glucose utilization using the euglycemic, hyperinsulinemic clamp technique.

RESULTS

We identified no significant correlation between serum androgens and either glucose uptake or insulin-mediated glucose utilization. Glucose-stimulated insulin release was negatively correlated with serum T and free T throughout the normal range of these hormones.

CONCLUSION

We conclude that, within the normal range, variations of serum androgens are not correlated with changes in the response to insulin. It seems unlikely, therefore, that modest increases of serum androgens within the normal range are responsible for inducing insulin resistance.

Prediction of hip fracture in elderly women: a prospective study

OBJECTIVE

To assess the relative importance of osteoporosis of the os calcis, cognisance, and mobility in the risk of subsequent fracture of the hip in elderly women.

DESIGN

Prospective study of elderly women in residential care over two years.

SETTING

21 Private or 38 local authority residential homes for the elderly and 4 geriatric hospitals in Doncaster and Hull.

SUBJECTS

1414 Ambulant women aged over 69, in private or local authority residential care or geriatric care. Those who had had bilateral hip surgery were excluded.

MAIN OUTCOME MEASURES

Broad band ultrasonic attenuation (BUA) index, Clifton assessment procedures for the elderly test (for cognisance), and mobility on a six point scale, and fracture of the hip in the subsequent two year period.

RESULTS

73 Women fractured their hip during the two years. Their mean age was not significantly different from that of the women who did not have a fracture (85.3 (SD 5.6) v 83.9 (6.3); p = 0.07), but their mean BUA index (40.3 (19.3) v 50.9 (22.2) db/MH2), and score for cognisance (median 19 (interquartile range 10.5-27.0) v 24 (17-30)) were significantly lower (both p less than 0.001). These variables had independent associations with fracture of the hip. Women with fractures had a significantly lower score for the psychomotor component of the cognisance test (4.5 (1-8) v 7 (2-10); p less than 0.0025 and were significantly more mobile (1(1-3) v 3 (1-6); p less than 0.02). Subdividing women according to high, medium, and low scores for BUA index and cognisance testing disclosed a high risk group (118 women) with low BUA index and cognisance score, whose incidence of fracture was 12.8%; in the group at lowest risk (136 women) with high BUA index and cognisance score, the incidence of fracture was only 1.5% (relative risk 8.4 (95% confidence interval -2.0 to 35.5]. Further analysis showed that those most at risk were, additionally, most mobile but that less mobile women with good cognisance had a low incidence of fractures, regardless of the BUA index, (1.2%, high index, v 0.9%, low index).

CONCLUSIONS

Elderly women most at risk of sustaining hip fractures were those with low BUA index, low cognisance test score, and high mobility. Improving bone strength and cognisance in elderly women may reduce their incidence of hip fracture.

Surface modification for improved blood compatibility

Several surface modification techniques are currently being used to improve the biocompatibility of blood-contacting devices. These include the immobilization of bioactive materials to prevent thrombus generation and platelet activation, the incorporation of hydrophilic grafts onto practical hydrophobic surfaces (polyurethanes) to reduce protein adsorption, and the concept of microdomain-phase separated surfaces to regulate cellular and protein adhesion.

Sensitivity to intravenous anaesthetics: a report of three cases

Three patients with sensitivity to an intravenous anaesthetic-thiopentone, propanidid, and Althesin (alphadolone and alphaxalone)-are described. In the cases of thiopentone and Althesin the reaction was characterized by cardiovascular collapse, while bronchospasm also occurred with thiopentone. The reaction to propanidid was a direct skin sensitivity. All patients had a personal or family history of asthma and all had been previously exposed to the offending drug. A leucocyte challenge test showed an allergic response to thiopentone and Althesin in two patients but gave a negative result in the patient with the skin reaction. Allergic reactions can occur to all types of intravenous anaesthetics in a few patients.