The ANTENATAL multicentre study to predict postnatal renal outcome in fetuses with posterior urethral valves: objectives and design

Background

Posterior urethral valves (PUV) account for 17% of paediatric end-stage renal disease. A major issue in the management of PUV is prenatal prediction of postnatal renal function. Fetal ultrasound and fetal urine biochemistry are currently employed for this prediction, but clearly lack precision. We previously developed a fetal urine peptide signature that predicted in utero with high precision postnatal renal function in fetuses with PUV. We describe here the objectives and design of the prospective international multicentre ANTENATAL (multicentre validation of a fetal urine peptidome-based classifier to predict postnatal renal function in posterior urethral valves) study, set up to validate this fetal urine peptide signature.

Methods

Participants will be PUV pregnancies enrolled from 2017 to 2021 and followed up until 2023 in >30 European centres endorsed and supported by European reference networks for rare urological disorders (ERN eUROGEN) and rare kidney diseases (ERN ERKNet). The endpoint will be renal/patient survival at 2 years postnatally. Assuming α = 0.05, 1–β = 0.8 and a mean prevalence of severe renal outcome in PUV individuals of 0.35, 400 patients need to be enrolled to validate the previously reported sensitivity and specificity of the peptide signature.

Results

In this largest multicentre study of antenatally detected PUV, we anticipate bringing a novel tool to the clinic. Based on urinary peptides and potentially amended in the future with additional omics traits, this tool will be able to precisely quantify postnatal renal survival in PUV pregnancies. The main limitation of the employed approach is the need for specialized equipment.

Conclusions

Accurate risk assessment in the prenatal period should strongly improve the management of fetuses with PUV.

Management of ureteropelvic junction obstruction in children-a roundtable discussion

The investigation, management and follow-up of paediatric ureteropelvic junction obstruction is not standardized. The Young Pediatric Urology Committee of the European Society of Pediatric Urology interviewed five experts in the field on various aspects of management and compared this with published literature.

Infusions of albumin increase free fraction of naproxen in healthy volunteers: a randomized crossover study

BACKGROUND

In vitro and in vivo studies have indicated that stabilizers present in pharmaceutical-grade albumin influence the albumin-binding capacity for highly protein-bound drugs. However, the half-life of the stabilizers and the quantitative effect have been difficult to determine.

METHOD

A randomized crossover study including six healthy volunteers was performed. The study subjects received 750 mg of oral naproxen 2 h before the study. They were randomized to receive either 100 ml of 20% albumin or 100 ml of Ringer's acetate solution intravenously. Frequent blood samples were obtained. The experiment was repeated 4 weeks later with the alternate solution. The serum samples were analysed to determine the concentrations of albumin, N-acetyl-DL-tryptophan, caprylate, and naproxen.

RESULTS

The free fraction of naproxen increased significantly after the infusion of albumin (P<0.05). The increase was concurrent with the appearance of N-acetyl-DL-tryptophan and caprylate in serum. The free fraction of naproxen declined rapidly after the albumin infusion was completed. N-acetyl-DL-tryptophan had a half-life of approximately 30 min. The half-life of caprylate was <15 min.

CONCLUSION

A transfusion of albumin results in an increase in the free fraction of naproxen. The transient increase in free-fraction naproxen decreased together with the detectable levels of the stabilizers N-acetyl-DL-tryptophan and caprylate. N-acetyl-DL-tryptophan and caprylate have a short half-life in serum.

SNPs in genes coding for ROS metabolism and signalling in association with docetaxel clearance

The dose of docetaxel is currently calculated based on body surface area and does not reflect the pharmacokinetic, metabolic potential or genetic background of the patients. The influence of genetic variation on the clearance of docetaxel was analysed in a two-stage analysis. In step one, 583 single-nucleotide polymorphisms (SNPs) in 203 genes were genotyped on samples from 24 patients with locally advanced non-small cell lung cancer. We found that many of the genes harbour several SNPs associated with clearance of docetaxel. Most notably these were four SNPs in EGF, three SNPs in PRDX4 and XPC, and two SNPs in GSTA4, TGFBR2, TNFAIP2, BCL2, DPYD and EGFR. The multiple SNPs per gene suggested the existence of common haplotypes associated with clearance. These were confirmed with detailed haplotype analysis. On the basis of analysis of variance (ANOVA), quantitative mutual information score (QMIS) and Kruskal-Wallis (KW) analysis SNPs significantly associated with clearance of docetaxel were confirmed for GSTA4, PRDX4, TGFBR2 and XPC and additional putative markers were found in CYP2C8, EPHX1, IGF2, IL1R2, MAPK7, NDUFB4, TGFBR3, TPMT (2 SNPs), (P<0.05 or borderline significant for all three methods, 14 SNPs in total). In step two, these 14 SNPs were genotyped in additional 9 samples and the results combined with the genotyping results from the first step. For 7 of the 14 SNPs, the results are still significant/borderline significant by all three methods: ANOVA, QMIS and KW analysis strengthening our hypothesis that they are associated with the clearance of docetaxel.

Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress

Acute hemorrhage is a leading cause of death in trauma, and women are more susceptible to hypovolemic circulatory stress than men. The mechanisms underlying the susceptibility are not clear, however. The aim of the present study was to examine the compensatory mechanisms to defend central blood volume during experimental hypovolemia in women and men. Twenty-two women (23.1 ± 0.4 yr) and 16 men (23.2 ± 0.5 yr) were included. A lower body negative pressure (LBNP) of 11–44 mmHg induced experimental hypovolemic circulatory stress. The volumetric technique was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as to assess net capillary fluid transfer from tissue to blood in the arm. Plasma norepinephrine (NE) and forearm blood flow were measured before and during hypovolemia, and forearm vascular resistance (FVR) was calculated. LBNP created comparable hypovolemia in women and men. FVR increased less in women during hypovolemic stress, and no association between plasma NE and FVR was seen in women ( R2 = 0.01, not significant), in contrast to men ( R2 = 0.59, P < 0.05). Women demonstrated a good initial capacitance response, but this was not maintained with time, in contrast to men [e.g., decreased by 24 ± 4% (women) vs. 4 ± 5% (men), LBNP of 44 mmHg, P < 0.01], and net capillary fluid absorption from tissue to blood was lower in women (0.086 ± 0.007 vs. 0.115 ± 0.011 ml·100 ml−1·min−1, P < 0.05). In conclusion, women showed impaired vasoconstriction, reduced capacitance response with time, and reduced capillary fluid absorption during acute hypovolemic circulatory stress, indicating less efficiency to defend central blood volume than men.

Infusion of albumin attenuates changes in serum protein binding of drugs in surgical patients compared with volume replacement with HAES

BACKGROUND

In vitro studies have indicated that stabilizers present in pharmaceutical-grade albumin influence albumin-binding capacity for highly protein bound drugs.

METHODS

A randomized study including 40 surgical patients, treated with either albumin or starch solutions, was performed. Volumes of colloids were given based on clinical indication. Blood samples were obtained. The serum samples were analyzed to determine the concentrations of albumin, tryptophan, N-acetyl-dl-tryptophan, caprylate and alpha-1-acid glycoprotein as well as in vitro drug binding of naproxen, warfarin and digitoxin.

RESULTS

During surgery, the albumin concentration declined in the Starch group from 26.8 to 15.3 g/l. It remained unchanged in the Albumin group (29.2 g/l). The two groups were analyzed with the pre-operative sample acting as the control. In the starch group, the percent free concentration of the drugs increased significantly (P<0.01): for naproxen from 0.2% to 0.6%, for warfarin from 1.2% to 1.8% and for digitoxin from 6.8% to 11.1%. In the Albumin group, the % free fraction of naproxen doubled from 0.1% to 0.2% (P<0.05), whereas the % free fraction of warfarin decreased from 1.1% to 1.0% (P<0.05). The free fraction of digitoxin remained unchanged.

CONCLUSIONS

Infusion of albumin during surgery resulted in maintained albumin values and almost maintained binding parameters for the study drugs, although some statistically significant changes were found. The use of starch solutions, however, led to in a reduction in albumin values and a significant reduction in binding parameters.

[Tunnelled central venous catheters in children with cancer. Removal and duration]

INTRODUCTION

Most children with cancer have a tunnelled central venous catheter (CVC) inserted. The optimal type of CVC for children of all ages has not been identified. The purpose of this paper was to analyze factors correlated to the duration of catheterization of the first inserted CVC in children with cancer.

MATERIALS AND METHODS

All children with cancer who had their first CVC inserted between 01-01-2000 and 01-09-2006. Retrospective and prospective study of medical charts with respect to the type of CVC, age of the child at insertion, dates of insertion and removal, diagnosis and cause of CVC removal.

RESULTS

Between 01-01-2000 and 01-09-2006 155 double lumen Hickmans (2-Hick) and 86 double lumen Port-a-Caths (2-PaC) were inserted. The total number of CVC days was 27,192 for 2-Hicks and 20,623 for 2-PaCs. The median duration of catherization was significantly longer for 2-PaCs compared with 2-Hicks (200 versus 135 days). Compared with 2-PaCs significantly more 2-Hicks were removed non-electively because of either infections or mechanical complications. The survival of 2-Hicks was significantly shorter in children <5 years of age, but for 2-PaCs there were no correlation between the duration of catherization and the age of the child. 67% of the 2-PaCs were removed at the end of treatment compared with 32% of the 2-Hicks (P< 0,001, chi2 test). A multivariate analysis showed that the type of CVC (P<0,001) and the age of the child (P< 0,001) were independent factors for the duration of the catheterization.

CONCLUSION

Port-a-Caths for children of all ages with cancer are associated with significantly fewer catheter removals due to complications.

Doxorubicin levels in the serum and ascites of patients with ovarian cancer

AIMS

To investigate the diffusion and accumulation of doxorubicin metabolites in the ascites of patients with ovarian cancer following intravenous injection, as a model for intraperitoneal accumulation of drugs.

METHODS

The concentrations of doxorubicin and its metabolites [Doxorubicinol (Dox-ol), 7-deoxydoxorubicinolone (7d-Dox-ol-on) and 7-deoxydoxorubicinone (7d-Dox-on)] were measured using high-performance liquid chromatography in the serum and in the ascites of seven patients with recurrent ovarian carcinoma suffering from symptomatic ascites and treated with intravenous doxorubicin.

RESULTS

Doxorubicin metabolites accumulated in the peritoneal cavity. The concentrations of the doxorubicin metabolites were initially higher in the serum compared to the ascitic fluid, but following several hours the doxorubicin metabolites became higher in the ascites, and remained detectable in the ascites for up to 168h, long after disappearance from the serum.

CONCLUSIONS

Doxorubicin metabolites accumulate in the ascites and are cleared more slowly from the peritoneal compartment than from the serum. Accumulation in the peritoneal cavity with prolonged half-life should be considered when administering medication in patients with ascites.

Cell volume regulation: osmolytes, osmolyte transport, and signal transduction

In recent years, it has become evident that the volume of a given cell is an important factor not only in defining its intracellular osmolality and its shape, but also in defining other cellular functions, such as transepithelial transport, cell migration, cell growth, cell death, and the regulation of intracellular metabolism. In addition, besides inorganic osmolytes, the existence of organic osmolytes in cells has been discovered. Osmolyte transport systems-channels and carriers alike-have been identified and characterized at a molecular level and also, to a certain extent, the intracellular signals regulating osmolyte movements across the plasma membrane. The current review reflects these developments and focuses on the contributions of inorganic and organic osmolytes and their transport systems in regulatory volume increase (RVI) and regulatory volume decrease (RVD) in a variety of cells. Furthermore, the current knowledge on signal transduction in volume regulation is compiled, revealing an astonishing diversity in transport systems, as well as of regulatory signals. The information available indicates the existence of intricate spatial and temporal networks that control cell volume and that we are just beginning to be able to investigate and to understand.

Influence of glucose and insulin on transcapillary fluid absorption from the arm during lower body negative pressure in man

This study examined the influence of insulin and glucose on the transcapillary fluid absorption during lower body negative pressure (LBNP) in humans. Ten healthy males [23 (1) years] were exposed to LBNP of 45 cmH(2)O on two occasions: (1) before and during a hyperinsulinaemic clamp (HI) and (2) before and during a hyperglycaemic clamp (HG). Transcapillary fluid absorption and blood flow were recorded with volumetric technique. Forearm blood flow increased during HI from 2.3 (0.3) ml (100 ml)(-1) min(-1) to 3.3 (0.5) ml (100 ml)(-1) min(-1) ( P<0.05). The haemodynamic response to LBNP was similar during HI and HG compared with control LBNP. Transcapillary fluid absorption during LBNP increased during HG from 0.044 (0.007) ml (100 ml)(-1) min(-1) to 0.059 (0.009) ml (100 ml)(-1) min(-1 )( P<0.01), whereas it was unchanged during HI. In conclusion, hyperglycaemia augments transcapillary fluid absorption from skeletal muscle and skin during LBNP whereas hyperinsulinaemia has no such effect. This indicates that in human hyperglycaemia contributes to plasma volume restitution during hypovolaemic circulatory stress.

Blood pressure levels in treated hypertensive patients in general practice in Norway

The aim of this study was to examine the blood pressure (BP) levels in patients treated for essential hypertension in 1816 patients in general practice in Norway. The study was based on an optical readable questionnaire filled out by the physician including information about systolic (S) and diastolic (D) BP, gender, age, body weight, smoking habits and all pharmaceutical treatment given. Sixty-four per cent of the patients were treated with one antihypertensive drug. Only 22.3% of the women and 30.7% of the men (p < 0.05) had BP < or = 140/90 mmHg. When BP < 160/95 was used as criterion for BP control, the fraction of patients was 50%. The fraction of patients with DBP < or = 80 mmHg was 26% in the whole group of patients. DBP < or = 90 mmHg was achieved in 74% and SBP < or = 140 mmHg in 30% of the patients. The BP control was less in women and in patients above 60 years of age. Patients on combination therapy were no better controlled than those on monotherapy. Based on our results, the proportion of hypertensive patients on drug treatment with insufficient BP control is too high. Efforts should be made to improve the medical treatment of hypertension in general practice in Norway.

Organochlorine pesticides, polychlorinated biphenyls, and butyltin compounds in blubber and livers of stranded California sea lions, elephant seals, and harbor seals from coastal California, USA

Concentrations of polychlorinated biphenyls (PCBs), DDTs (p,p'-DDE, p,p'-DDD, p,p'-DDT), chlordanes (CHLs; cis-chlordane, cis-nonachlor, trans-nonachlor, and oxychlordane), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMOH), and mono- (MBT), di-(DBT), and tri-butyltin (TBT) were determined in blubber and livers of 15 California sea lions (Zalophus californianus), 6 northern elephant seals (Mirounga augustirostris), and 10 harbor seals (Phoca vitulina) found stranded along the coasts of California, USA, during 1991-1997. Among the organochlorines analyzed, DDTs were predominant, followed in decreasing order by PCBs, CHLs, TCPMe, TCPMOH, HCHs, and HCB. The greatest concentrations of organochlorines were found in California sea lions. The highest DDT and PCB concentrations found in the blubber of California sea lions were 2,900 and 1,300 microg/g, lipid weight, respectively. Concentrations of TCPMe and TCPMOH in California sea lions were correlated significantly with DDT concentrations. Concentration ratios of various organochlorines in harbor seal livers were different from those in California sea lions and elephant seals, which suggested that the sources of exposure of harbor seals to organochlorines were different from those in the other two species. Concentrations of butyltin compounds in livers of pinniped species ranged from 2 to 99 ng/g, wet weight, which were less than those observed in cetaceans and in California sea otters.

Rapid discrimination among individual DNA hairpin molecules at single-nucleotide resolution using an ion channel

RNA and DNA strands produce ionic current signatures when driven through an alpha-hemolysin channel by an applied voltage. Here we combine this nanopore detector with a support vector machine (SVM) to analyze DNA hairpin molecules on the millisecond time scale. Measurable properties include duplex stem length, base pair mismatches, and loop length. This nanopore instrument can discriminate between individual DNA hairpins that differ by one base pair or by one nucleotide.

Application of a high-throughput antibody-based assay for identification of the granule-bound starch synthase Wx-B1b allele in Australian wheat lines

An enzyme-linked immunosorbent assay (ELISA) for the discrimination of Wx-B1a and Wx-B1b genotypes at the granule-bound starch synthase I (GBSSI) or waxy locus of hexaploid wheat (Triticum aestivum L.) was adapted to a high-throughput, 96-well microtitre plate format. This test is applicable to the direct analysis of starch, flour, or crushed grain and requires less than 1 grain to perform. Several hundred samples may be routinely analysed in one day. The assay was validated using quantitative trait locus (QTL) analysis of a doubled haploid mapping population of the cross Cranbrook (Wx-B1a)/Halberd (Wx-B1b). This demonstrated that the assay unambiguously identified 153 of 161 lines analysed, with a highly significant QTL (LRS value 270) accounting for 83% of ELISA variation, at the Wx-B1 locus on chromosome 4AL. In addition, measurement of total GBSSI variation using a non-isoform-specific GBSSI detection monoclonal antibody also gave a significant QTL (LRS of 84, accounting for 42% of ELISA variation) at the Wx-B1 locus. Application of the assay to crude flour extracts of 8 grains for each of 1093 progeny from 4 crosses segregating at the Wx-B1 locus permitted the unambiguous scoring of lines as pure Wx-B1a or pure Wx-B1b. The scoring by ELISA was strongly related to the flour swelling volume of the lines, thus demonstrating the utility of this high-throughput screening method for the faster, more efficient development of Australian noodle wheats.

Reduced capillary hydraulic conductivity in skeletal muscle and skin in Type I diabetes: a possible cause for reduced transcapillary fluid absorption during hypovolaemia

AIMS/HYPOTHESIS

Patients with Type I (insulin-dependent) diabetes mellitus have a reduced transcapillary fluid absorption from skeletal muscle and skin and thus defective plasma volume regulation during hypovolaemia. Our aim was to find whether a defective capillary filtration coefficient or impaired transcapillary driving force are aetiologic factors for this reduction.

METHODS

We investigated 11 diabetic patients (diabetes duration 6.9 +/- 1.1 years, age 26 +/- 1 years), without complications and 12 control subjects (26 +/- 1 years). Their capillary filtration coefficient was measured in the upper arm using a volumetric technique at rest and during lower body negative pressure (LBNP). We calculated the driving force for transcapillary fluid transfer.

RESULTS

The increase in heart rate and the decrease in systolic blood pressure during lower body negative pressure were similar in diabetic and control subjects. The resting capillary filtration coefficient was decreased in the diabetic subjects, 0.033 +/- 0.003 vs 0.051 +/- 0.007 ml x 100 ml(-1) x min(-1) x mmHg(-1) (p < 0.05). During lower body negative pressure, the capillary filtration coefficient increased 35 % in both groups compared with resting capillary filtration coefficient and was still decreased in diabetes; 0.046 +/- 0.004 compared with 0.069 +/- 0.006 ml x 100ml(-1) x min(-1) x mmHg(-1) (p < 0.01). The established driving force during lower body negative pressure was 1.37 +/- 0.11 vs 1.30 +/- 0.15 mmHg (NS) in diabetic and control subjects, respectively.

CONCLUSIONS/INTERPRETATION

Our study indicates that a reduced capillary filtration coefficient rather than defective regulation of transcapillary driving force, is the reason for the reduced transcapillary fluid absorption during hypovolaemic circulatory stress found in Type I diabetic patients.

2,3,7,8-Tetrachlorodibenzo-p-dioxin mechanism of action to reduce lipoprotein lipase activity in the 3T3-L1 preadipocyte cell line

Lipoprotein lipase (LPL) is important in the process of triglyceride storage in adipose tissue. Depression of LPL activity in adipose tissue is associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced wasting syndrome and may have a role in the associated serum hyperlipidemia produced by TCDD. The 3T3-L1 cell line was used as an in vitro model, independent of hormonal, nutritional, or other interfering factors associated with in vivo studies, in order to systematically examine the mechanism of action of TCDD. TCDD produced a statistically significant (P < 0.05) time- and dose-dependent decrease in LPL activity. Results of experiments with Ah-receptor blockers and structure activity studies with different polychlorinated biphenyl (PCB) and dioxin congeners were consistent with reduction of LPL activity being mediated by the Ah receptor. Culturing of 3T3-L1 cells without glucose or with cytochalasin B, a blocker of facilitative glucose transporters (GLUT), was effective in reducing LPL activity (P < 0.05). TCDD did not further reduce LPL activity in cytochalasin B pretreated 3T3-L1 cells or in 3T3-L1 cells cultured in glucose-free media. Dexamethasone pretreatment, which is known to increase GLUT expression in 3T3-L1 cells, prevented the reduction of LPL activity by TCDD. Protein tyrosine kinase activities, assayed using gamma-32P-ATP and RR-SRC, a src specific peptide substrate, were significantly increased (P < 0.05) over control levels by both TCDD and glucose deprivation. Furthermore, results of experiments treating 3T3-L1 cells with either insulin, EGF, 8-Br-cAMP, TPA, or genistein, alone or in combination with TCDD, were generally consistent with the hypothesis that lowered intracellular glucose and altered cellular kinase activities may be involved in reduction of LPL activities by TCDD. Further work is needed to confirm and better understand the role protein phosphorylation plays in TCDD-mediated alteration of glucose disposition and LPL activity. In summary, TCDD reduced LPL activity in 3T3-L1 cells as seen in vivo. Manipulation of glucose transport through a number of experimental approaches produced changes in 3T3-L1 LPL activity consistent with results of previous investigators showing glucose to be a positive regulator of LPL activity and consistent with our hypothesis that TCDD-mediated reduction of glucose transport is an important factor in the down regulation of LPL activity by TCDD.

A novel cytokine receptor-ligand pair. Identification, molecular characterization, and in vivo immunomodulatory activity

As part of a large scale effort to discover novel secreted proteins, a cDNA encoding a novel cytokine was identified. Alignments of the sequence of the new protein, designated IL-17B, suggest it to be a homolog of the recently described T cell-derived cytokine, IL-17. By Northern analysis, EST distribution and real-time quantitative polymerase chain reaction analysis, mRNA was detected in many cell types. A novel type I transmembrane protein, identified in an EST data base by homology to IL-17R, was found to bind specifically IL-17B, as determined by surface plasmon resonance analysis, flow cytometry, and co-immunoprecipitation experiments. Readily detectable transcription of IL-17BR was restricted to human kidney, pancreas, liver, brain, and intestines and only a few of the many cell lines tested. By using a rodent ortholog of IL-17BR as a probe, IL-17BR message was found to be drastically up-regulated during intestinal inflammation elicited by indomethacin treatment in rats. In addition, intraperitoneal injection of IL-17B purified from Chinese hamster ovary cells caused marked neutrophil migration in normal mice, in a specific and dose-dependent manner. Together these results suggest that IL-17B may be a novel proinflammatory cytokine acting on a restricted set of target cell types. They also demonstrate the strength of genomic approaches in the unraveling of novel biological pathways.

[Prescription patterns of antihypertensive agents in general practice in 1995]

BACKGROUND

Hypertension represents a risk factor in the development of cardiovascular disease.

MATERIAL AND METHODS

The prescription of antihypertensive drugs and the daily doses used were examined in a questionnaire-based survey among 2,586 drug-treated hypertensive patients who attended a general practitioner for clinical control in November 1995.

RESULTS

The proportion of patients treated with one antihypertensive drug only was 63%. ACE inhibitors, alpha blockers and angiotensin-II antagonists constituted 22.7%, 6.6% and 4.4%, and betablockers, calcium channel blockers and diuretics 21.7%, 23.7% and 16.3% of the prescriptions respectively. Women were more often prescribed diuretics than men, and older individuals more often than younger persons. No striking difference in the prescription of antihypertensive drugs were observed between the five health regions of Norway. There was no reduction in the prescribed daily doses of antihypertensives used in combination therapy compared with monotherapy. In approximately one quarter of the prescriptions there was a positive correlation between the prescribed daily dose and the patient's weight. The number of antihypertensives prescribed did positively correlate with the patient's weight.

INTERPRETATION

This survey shows that antihypertensives without any documented effect on morbidity and mortality were frequently prescribed for hypertension in general practice. Except for the low proportion of diuretic users among elderly patients, our results is in accordance with the Guidelines from the Norwegian Society of General Practitioners.

Cardiovascular response to acute hypovolemia in relation to age. Implications for orthostasis and hemorrhage

Venous compliance in the legs of aging man has been found to be reduced with decreased blood pooling (capacitance response) in dependent regions, and this might lead to misinterpretations of age-related changes in baroreceptor function during orthostasis. The hemodynamic response to hypovolemic circulatory stress was studied with the aid of lower-body negative pressure (LBNP) of 60 cmH(2)O in 33 healthy men [18 young (mean age 22 yr) and 15 old (mean age 65 yr)]. Volumetric technique was used in the study of capacitance responses in the calf and arm as well as transcapillary fluid absorption in the arm. LBNP led to smaller increase in heart rate (P < 0.001) and peripheral resistance (P < 0.01) and reduced transcapillary fluid absorption in the arm (P < 0.05) in old subjects. However, blood pooling in the calf was reduced in old subjects (1.66 +/- 0.10 vs. 2.17 +/- 0.13 ml/100 ml tissue; P < 0. 01). Accordingly, during similar blood pooling in the calf (LBNP 80 cmH(2)O in old subjects), no changes in cardiovascular reflex responses with age were found. The capacitance response in the arm (mobilization of peripheral blood to the central circulation) was still reduced, however (0.67 +/- 0.10 vs. 1.37 +/- 0.11 ml/100 ml tissue; P < 0.01). Thus the reduced cardiovascular reflex response found in the elderly during orthostatic stress seems to be caused by a reduced capacitance response in the legs with age and a concomitant smaller central hypovolemic stimulus rather than a reduced efficiency of the reflex response. With similar hypovolemic circulatory stress, no changes in cardiovascular reflex responses are seen with age. The capacitance response in the arm (mobilization of peripheral blood toward the central circulation) is reduced, however, by approximately 50% in the elderly. This might seriously impede the possibility of survival of an acute blood loss.

Reduced transcapillary fluid absorption from skeletal muscle and skin during hypovolaemia in insulin-dependent diabetes mellitus

OBJECTIVES

Diabetes mellitus is associated with a high cardiovascular morbidity which has been linked to disturbances in microvascular function. This study was designed to examine the transcapillary fluid absorption during experimental hypovolaemia in type 1 diabetes.

SUBJECTS

Twelve males with type 1 diabetes (age 25 +/- 3 years, duration 8 +/- 1 years) with no clinical microangiopathy and 12 healthy males (22 +/- 2 years).

INTERVENTIONS

As a model for hypovolaemic circulatory stress, lower body negative pressure (LBNP: 15, 30 and 60 cmH2O) was used. Transcapillary fluid absorption from tissue to blood in the upper arm, as well as forearm blood flow, was measured by volumetric technique.

RESULTS

Resting forearm blood flow, heart rate and blood pressure were similar in diabetic patients and controls. Basal plasma noradrenaline was reduced in the diabetics compared with controls (0.75 +/- 0.06 vs. 1.09 +/- 0.10 pmol L-1, P < 0.05), but the increase in plasma noradrenaline in response to LBNP was similar in the two groups. The haemodynamic responses to LBNP in the two groups were equal, showing a reduction of pulse pressure, an increase in heart rate and in peripheral resistance with a concomitant blood flow reduction. The transcapillary fluid absorption (mL 100 mL-1 min-1) was significantly reduced in the diabetic patients: LBNP 15 cmH2O, 0.024 +/- 0.004 vs. 0.036 +/- 0. 002; 30 cmH2O, 0.041 +/- 0.003 vs. 0.056 +/- 0.005; and 60 cmH2O, 0. 057 +/- 0.007 vs. 0.091 +/- 0.008 (diabetic patients vs. controls, P < 0.001).

CONCLUSIONS

The transcapillary fluid absorption from tissue to blood during hypovolaemic circulatory stress in type 1 diabetic patients is reduced by one-third compared with controls, which indicates impaired plasma volume regulation. This basic mechanism for plasma volume control is affected before clinical microcirculatory complications are found and could be one of the causes of the increased cardiovascular morbidity and mortality in IDDM.

The role of sulphonylurea in combination therapy assessed in a trial of sulphonylurea withdrawal. Scandinavian Insulin-Sulphonylurea Study Group Research Team

AIMS

To evaluate the effect of adding insulin to sulphonylurea (SU) and the effect of SU withdrawal on glycaemic control in Type 2 diabetic patients who failed on treatment with SU alone.

METHOD

One hundred and seventy-five patients were included in a placebo-controlled multicentre study. During phase I (4 months), premixed insulin was added to glibenclamide therapy; during phase II (1-4 months, depending on response) the insulin dose was fixed, while placebo or glibenclamide replaced the open SU therapy. Insulin sensitivity (KITT), beta-cell function (C-peptide) and metabolic control (HbA1c) were monitored.

RESULTS

HbA1c improved from 9.65% to 7.23% (P < 0.0001) during phase I. A high HbA1c value (P < 0.0001) and a high KITT-value (P = 0.045) at baseline were associated with a beneficial response to combination treatment. During phase II, glycaemic control was unchanged in the control (glibenclamide) group. In the placebo group, after SU withdrawal, fasting blood glucose (FBG) increased by 10% or more within 4 weeks in 79% of the patients. Patients (67 of 112) with an FBG increase > or =40% during phase II were defined as 'SU responders' by protocol. In a multivariate analysis only a long duration of diabetes was associated with SU response. There were more GAD-antibody-positive patients among non-responders (18% vs. 4%, P = 0.0263).

CONCLUSIONS

Poor glycaemic control in combination with preserved insulin sensitivity and lack of GAD antibodies predicts a beneficial response to combination therapy, which can be achieved in 75% of patients with SU failure.

Adverse drug reactions in current antihypertensive therapy: a general practice survey of 2586 patients in Norway

The objective of this study was to determine the frequency and profile of adverse reactions to antihypertensive drugs in an unselected group of drug-treated hypertensive patients. A questionnaire-based survey was carried out among 2586 drug-treated hypertensive patients who attended a general practitioner for clinical control. Adverse drug reactions reported spontaneously, upon general inquiry, upon specific questioning and as evaluated by a physician were used as the main outcome measures. The study shows that the percentage of patients who reported adverse drug reactions spontaneously, upon general inquiry and upon specific questioning were 16%, 24% and 62% respectively. Users of diuretics reported the lowest frequency of adverse reactions, whereas users of beta-blockers reported the highest frequency. In 7% of the patients, the adverse drug reactions were of such a nature that the physicians considered discontinuing the treatment. As a conclusion, the reported frequency of adverse drug reactions in antihypertensive treatment is high, but with significant differences between the various drug groups. Monotherapy is connected with far fewer adverse drug reactions than combination therapy.

[Pharmacists' and general practitioners' views on parallel import of drugs]

Since 1995, parallel import of drugs to Norway has been allowed under the European Economic Area Agreement. The health authorities have stated that there are no concerns connected with the use of parallel-imported drugs. This study is an interview survey among general practitioners, pharmacy staff and pharmacists working in pharmacies. The findings show that 91% of the pharmacies dispense parallel-imported drugs and that there is a certain amount of scepticism regarding the use of parallel-imported drugs. Most respondents feel that parallel-imported pharmaceuticals may have financial advantages for the individual patient and economic advantages for society at large, but 50% of the pharmacists and 54% of the physicians were of the opinion that parallel-imported pharmaceuticals represented an increased medical risk for the patients. Approximately 15% of doctors and pharmacy staff had knowledge of either incorrect treatment or adverse drug reactions due to the use of parallel-imported drugs. The time used for prescribing and dispensing parallel-imported drugs is longer than for directly imported preparations. The survey shows that approximately every fifth doctor will use the right of reservation in connection with the dispensing of parallel-imported drugs, whereas approximately every fourth pharmacist will disregard the right of reservation.

Gene expression and production of the monokine induced by IFN-gamma (MIG), IFN-inducible T cell alpha chemoattractant (I-TAC), and IFN-gamma-inducible protein-10 (IP-10) chemokines by human neutrophils

Monokine induced by IFN-gamma (MIG), IFN-inducible T cell alpha chemoattractant (I-TAC), and IFN-gamma-inducible protein of 10 kDa (IP-10) are related members of the CXC chemokine subfamily that bind to a common receptor, CXCR3, and that are produced by different cell types in response to IFN-gamma. We have recently reported that human polymorphonuclear neutrophils (PMN) have the capacity to release IP-10. Herein, we show that PMN also have the ability to produce MIG and to express I-TAC mRNA in response to IFN-gamma in combination with either TNF-alpha or LPS. While IFN-gamma, alone or in association with agonists such as fMLP, IL-8, granulocyte (G)-CSF and granulocyte-macrophage (GM)-CSF, failed to influence MIG, IP-10, and I-TAC gene expression, IFN-alpha, in combination with TNF-alpha, LPS, or IL-1beta, resulted in a considerable induction of IP-10 release by neutrophils. Furthermore, IL-10 and IL-4 significantly suppressed the expression of MIG, IP-10, and I-TAC mRNA and the extracellular production of MIG and IP-10 in neutrophils stimulated with IFN-gamma plus either LPS or TNF-alpha. Finally, supernatants harvested from stimulated PMN induced migration and rapid integrin-dependent adhesion of CXCR3-expressing lymphocytes; these activities were significantly reduced by neutralizing anti-MIG and anti-IP-10 Abs, suggesting that they were mediated by MIG and IP-10 present in the supernatants. Since MIG, IP-10, and I-TAC are potent chemoattractants for NK cells and Th1 lymphocytes, the ability of neutrophils to produce these chemokines might contribute not only to the progression and evolution of the inflammatory response, but also to the regulation of the immune response.

Hsp60-induced tolerance in the rotifer Brachionus plicatilis exposed to multiple environmental contaminants

Hsp60 induction was selected as a sublethal endpoint of toxicity for Brachionus plicatilis exposed to a water accommodated fraction (WAF) of Prudhoe Bay crude oil (PBCO), a PBCO/dispersant (Corexit 9527(R)) fraction and Corexit 9527(R) alone. To examine the effect of multiple stressors, exposures modeled San Francisco Bay, where copper levels are approximately 5 microgram/L, salinity is 22 per thousand, significant oil transport and refining occurs, and petroleum releases have occurred historically. Rotifers were exposed to copper at 5 microgram/L for 24 h, followed by one of the oil/dispersant preparations for 24 h. Batch-cultured rotifers were used in this study to model wild populations instead of cysts. SDS-PAGE with Western Blotting using hsp60-specific antibodies and chemiluminescent detection were used to isolate, identify, and measure induced hsp60 as a percentage of control values. Both PBCO/dispersant and dispersant alone preparations induced significant levels of hsp60. However, hsp60 expression was reduced to that of controls at high WAF concentrations, suggesting interference with protein synthesis. Rotifers that had been preexposed to copper maintained elevated levels of hsp60 upon treatment with WAF at all concentrations. Results suggest that induction of hsp60 by chronic low-level exposure may serve as a protective mechanism against subsequent or multiple stressors and that hsp60 levels are not additive for the toxicants tested in this study, giving no dose-response relationship. The methods employed in this study could be useful for quantifying hsp60 levels in wild rotifer populations.

Drug-related information generates placebo and nocebo responses that modify the drug response

OBJECTIVE

Administration of the muscle relaxant carisoprodol and placebo was crossed with information that was agonistic or antagonistic to the effect of carisoprodol. It was investigated whether information alone induced physiological and psychological responses, and whether information modified the response to the drug.

METHODS

Half of the subjects received capsules containing 525 mg carisoprodol together with information that the drug acted in a specific way (Groups Relaxant/C, Stimulant/C, and No Information/C). The other half of the subjects received lactose (Groups Relaxant/L, Stimulant/L, and No Information/L). Dependent variables were blink reflexes and skin conductance responses, subjective measures of tension and sleepiness, and serum carisoprodol and meprobamate concentrations. Recordings were made between 15 and 130 minutes after administration of the capsules.

RESULTS

The Stimulant/L group reported more tension compared with the other two groups, and carisoprodol increased tension even more in the Stimulant/C group. The Relaxant/C group displayed higher levels of carisoprodol serum concentration compared with the other groups that received carisoprodol.

CONCLUSIONS

Reported tension was modulated in the direction suggested by the stimulant information. The effect of carisoprodol on tension was also modulated by stimulant information. Increased carisoprodol absorption in the group that received relaxant information could be a mechanism in the placebo response.

[Methadone used in the treatment of opioid dependence]

Norway has been a stronghold of restrictive attitudes and scepticism towards the use of methadone in treatment of heroin addiction. A policy of nation-wide use of methadone has now been adopted. This paper gives a short history of the use of methadone, a review of present neurobiological knowledge and a description of the different approaches in methadone based treatment. Methadone treatment does not reduce opioid dependency but compensates for neurobiological complications of long-term use. This increases the ability to profit from psychosocial approaches in treatment and reduces the tendency to risk-taking and socially disturbing behaviour. Norway aims to follow the "Swedish" model in methadone policy with emphasis on high threshold, high dose treatment combined with control and systematic rehabilitative measures. This choice should be evaluated both in a comparative and in a treatment oriented perspective.

Regulation of human IL-18 mRNA expression

As virtually nothing is known about the pattern of expression of human IL-18, we investigated certain factors that may contribute to the regulation of IL-18 mRNA accumulation and compared this with regulation of the human gene encoding the p40 chain of IL-12, a cytokine that shares similar biologic activity with IL-18. IL-18 mRNA was expressed constitutively in unstimulated PBMC or monocytes, unlike p40, which required induction by a stimulus. Upon stimulation, IL-18 transcript accumulation was enhanced with an earlier and more transient pattern of expression than IL-12 p40 mRNA. Bacteria-derived stimuli and priming with IFN-gamma or IL-4 also upregulated IL-18 mRNA in a fashion similar to that of IL-12 p40. IL-10 exerted an inhibitory effect on IL-18 mRNA accumulation, though not as markedly as in the suppression of IL-12 p40 by IL-10. Finally, unlike IL-12 p40 mRNA, the constitutive accumulation of IL-18 transcripts by unstimulated cells was amplified in the presence of the translational blocker cycloheximide, which also caused a superinduction of IL-18 expression after Staphylococcus aureus stimulation.

Reduced venous compliance in lower limbs of aging humans and its importance for capacitance function

Venous compliance in the calf of humans and its importance for capacitance function in relation to age were studied with the aid of 22, 44, and 59 mmHg lower body negative pressure (LBNP). Negative pressure transmission to the calf as well as changes in calf volume were studied, and venous compliance was calculated [change in volume with pressure change (dV/dP)]. The change in capacitance response of the calf with age (20-70 yr) was evaluated during LBNP 44 mmHg. Transmission of negative pressure to the subcutaneous tissue was almost full without any changes with age (92%). However, it was reduced to 80% in the underlying muscle tissue, irrespective of depth. Venous compliance in the young was 0.051 ml . 100 ml-1 . mmHg-1 and was reduced by 45% to 0.029 ml . 100 ml-1 . mmHg-1 in the old (P < 0.05). Accordingly, the capacitance response was reduced by 0.015 ml . 100 ml-1 . yr-1 (P < 0.005). Furthermore, the hemodynamic response to hypovolemic circulatory stress was attenuated with age. The reduced pressure transmission in muscle tissue is probably due to restriction of the muscle fascia envelope. The reduced venous compliance with age and the concomitant reduction in capacitance response during LBNP have implications for both the sympathetic reflex responses as well as the capacitance response during acute hypovolemic circulatory stress, which might be defected in aging humans.

4E-BP3, a new member of the eukaryotic initiation factor 4E-binding protein family

Translation initiation in eukaryotes is mediated by the cap structure (m7GpppN, where N is any nucleotide) present at the 5' end of all cellular mRNAs, except organellar. The cap is recognized by eukaryotic initiation factor 4F (eIF4F), which consists of three polypeptides, including eIF4E, the cap-binding protein subunit. The interaction of the cap with eIF4E facilitates the binding of the ribosome to the mRNA. eIF4E activity is regulated in part by two translational repressors, 4E-BP1 and 4E-BP2, which bind to it and prevent its assembly into eIF4F. We report here the isolation of 4E-BP3, a new member of the 4E-BP family. 4E-BP3 is homologous to 4E-BP1 and 4E-BP2, exhibiting 57 and 59% identity, respectively. The homology is most striking in the middle region of the protein, which contains the eIF4E binding motif and residues that are phosphorylated in 4E-BP1. 4E-BP3 is a heat stable protein that binds to eIF4E in vitro as well as in vivo. Further, 4E-BP3 overexpression specifically reduces eIF4E-dependent translation. The overlapping function and expression of the different 4E-BP family members imply that there is redundancy in this translational control mechanism, underscoring its importance.

Cloning and characterization of 4EHP, a novel mammalian eIF4E-related cap-binding protein

All eukaryotic mRNAs (except organellar) are capped at their 5' end. The cap structure (m7GpppN, where N is any nucleotide) is extremely important for the processing and translation of mRNA. Several cap-binding proteins that facilitate these processes have been characterized. Here we describe a novel human cytoplasmic protein that is 30% identical and 60% similar to the human translation initiation factor 4E (eIF4E). We demonstrate that this protein, named 4E Homologous Protein (4EHP), binds specifically to capped RNA in an ATP- and divalent ion-independent manner. The three-dimensional structure of 4EHP, as predicted by homology modeling, closely resembles that of eIF4E and site-directed mutagenesis analysis of 4EHP strongly suggests that it shares with eIF4E a common mechanism for cap binding. A putative function for 4EHP is discussed.

[Adverse effects of zopiclone]

In 1994 zopiclone (Imovane), a cyclopyrrolon, was introduced in Norway as a new kind of hypnotic. In 1996 zopiclone had a 26% share of the hypnotic market. This review of relevant literature has revealed a lack of documentation on the adverse effects of zopiclone. The similarities between zopiclone and benzodiazepine hypnotics are more striking than the differences. The bulk of comparative research has been carried out with triazolam, a drug taken off the Norwegian market in 1991. With zopiclone there is less inhibition of psychomotor function the day after intake than with flunitrazepam. Zopiclone causes less subjective "hangover" than nitrazepam, but there is a similar inhibition of psychomotor function the day after intake, and in some cases greater addictive potential.

Increased plasma concentration of serum amyloid P component in centenarians with impaired cognitive performance

Serum amyloid P component (SAP) binds to all amyloid fibrils including those in the plaques and tangles of Alzheimer patients. To investigate whether the plasma SAP concentration correlated to cognitive impairment, we measured SAP levels in blood samples from 41 centenarians and compared these to the cognitive performance evaluated by Mini Mental State Examination (MMSE). We observed a significantly (p < 0.001) increased SAP concentration (48.3+/-16.9 microg/ml; mean +/- SD) in the centenarians compared to gender-matched controls (32.8+/-11.4 microg/ml). Six severely demented centenarians had an even higher SAP concentration (60.2 microg/ml), while the subgroup of cognitive intact centenarians (MMSE score >24) showed a normal SAP concentration (38.4+/-9.3 microg/ml). No dehydration or hepatic dysfunction was demonstrable in the centenarians. We conclude that the centenarians with impaired cognitive performance had significantly increased plasma concentrations of SAP, while the values for cognitive intact centenarians were within the normal range.

Decreased capacitance response with age in lower limbs of humans--a potential error in the study of cardiovascular reflexes in ageing

The cardiovascular regulation in humans depends to a major extent on sympathetic reflexes originating from volume receptors in the arterial as well as the cardiopulmonary region. With experimental approaches, such as lower body negative pressure (LBNP) and tilting, signs of reduced efficiency with ageing have been shown. However, a confounding factor may be an age-related decline in venous capacitance response of the lower limbs, reducing the decrease in central blood volume and thus the deactivation of baro/cardiopulmonary receptors. This potential error was addressed in the present study. Central hypovolaemic stress was produced by LBNP 60 cmH2O in 10 young (mean age 23, range 20-25 years) and 10 old males (mean age 65, range 61-70 years). Changes in tissue volume of the calf were studied by strain gauge volumetric technique. Transmission of negative pressure to the calf muscle was studied in two young and two old volunteers. The haemodynamic response to hypovolaemic circulatory stress was attenuated in the old as compared with the young subjects, with a less marked increase in heart rate and peripheral resistance. Further, in the old subjects, the decrease in systolic blood pressure, pulse pressure and forearm blood flow was attenuated. Transmission of negative pressure to the calf was equal in both groups. The capacitance response was reduced with age from 2.27 +/- 0.14 to 1.64 +/- 0.13 mL 100 mL-1 (P < 0.005). However, the net capillary fluid filtration was unchanged. The reduced capacitance function might partly explain the declining reflex responses with age in humans, and thus seems to be of considerable importance when studying cardiovascular sympathetic reflex responses in ageing.

Comparison of objective methods for quantifying the refractive effect of photo-astigmatic refractive keratectomy using the MEL-60 excimer laser

PURPOSE

To investigate the accuracy and precision of automated keratometry, automated refractometry, and computerized corneal topography in estimating the subjective refractive outcome of photo-astigmatic refractive keratectomy six months postoperatively.

METHODS

Photo-astigmatic refractive keratectomy (Aesculap-Meditec, MEL-60 Excimer Laser) was performed on 26 eyes with a preoperative myopia ranging from -4.0 to 7.6 dioptres, and a naturally occurring astigmatism from 0.75 to 5.0 dioptres. Six months postoperatively refractive outcome was evaluated by automated keratometry, automated refractometry (Nikon NRK-8000), computerized topography (TMS-1), and subjective refraction. Estimate errors were computed as the difference between the change in subjective refraction and the change in automated keratometry, automated refractometry, and surface topography, respectively. Astigmatic changes were evaluated by the second harmonic component in the Fourier series analysis.

RESULTS

Subjective spherical as well as cylindrical values were reduced significantly six months postoperatively. The estimate error (mean +/- one standard deviation) for automated keratometry was -1.26 +/- 0.72 dioptres for the spherical equivalent and -1.36 +/- 1.02 dioptres for the cylinder; for automated refractometry it was -0.78 +/- 0.91 dioptres for the spherical equivalent and -0.66 +/- 0.92 dioptres for the cylinder. The best estimates of subjective changes were obtained when the average of ring 2 and 3 of the topographic data was used: -0.15 +/- 0.82 dioptres for the spherical equivalent and -0.78 +/- 0.80 dioptres for the cylinder.

CONCLUSIONS

The computerized topographer with the Fourier analysis was superior to automated keratometry and automated refractometry in estimating the subjective spherical refractive outcome and comparable to automated refractometry in estimating the subjective cylinder refractive outcome after photo-astigmatic refractive keratectomy.

[Statins--the pattern of adverse effects with empahsis on mental reactions. Data from a national and an international database]

We report on adverse drug reactions to statins recorded internationally and in Norway. The use of HMG-CoA reductase inhibitors (statins) has increased with a factor of 30 in Norway over the period 1989-96. Recently published clinical trials conclude that statins are safe; adverse drug reactions being infrequent and non-serious. The reactions observed are mostly increased hepatic enzymes and myopathy. Data from the Norwegian spontaneous reporting system, and from WHO's international database covering the period of 1988-95, includes reports of adverse drug reactions relating to other organ systems, such as the nervous system, the gastrointestinal tract, skin and cardiovascular organs. Psychiatric disorders represent 15% of the reactions to statins in the Norwegian database. Reactions include aggression, nervousness, depression, anxiety, sleeping disorders and impotence. The pharmacological mechanisms are not elucidated, but may be an effect of falling serum cholesterol.

Value of intraoperative keratometry in predicting outcome of radial keratotomy

PURPOSE

To investigate whether the immediate change in corneal power during radial keratotomy correlates with the long-term postoperative change in subjective refraction, and thereby being predictive for refractive outcome.

METHODS

Manual keratometry was performed on 45 consecutively operated eyes of 45 young persons with myopia of 5 dioptres and less and immediately after radial keratotomy. Automated keratometry and subjective spherical equivalent refraction were investigated during a follow-up period of 6 months and correlated to the intraoperative keratometric measurements.

RESULTS

On average, the majority of the change in corneal curvature after radial keratotomy took place within 1 min. There was no correlation between the intraoperative curvature change and the changes in curvature measured up to 6 months after surgery. There was a weak significant positive correlation between intraoperative curvature change and the change in subjective refraction at 6 months after surgery (R = 0.48, p < 0.01). The prediction error in estimating subjective refractive changes from intraoperative keratometry changes was, however, similar in patients who had bilateral radial keratotomy. Inclusion of such fellow-eye information together with the age of the patient in a multiple linear regression analysis increased the correlation coefficient from 0.48 to 0.75.

CONCLUSIONS

The change in central corneal curvature takes place within minutes after corneal incision. As a single parameter, intraoperative keratometry cannot be used for titrating surgery. Information from the results of first eye radial keratotomy surgery with intraoperative keratometry is, however, predictive for radial keratotomy in the second eye. These findings suggest that a large source to refractive variability after radial keratotomy is related to individual patient factors, such as corneal biomechanics and wound healing.

Biophysical factors and contractile function during coronary bolus perfusion: an experimental study in the isolated guinea pig heart

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the role of biophysical factors (viscosity, temperature, osmalality, perfusion pressure, and ionic washout) on cardiac contractility during coronary bolus perfusions.

METHODS

Guinea pig hearts were perfused in the osmolality mode at constant and high flow (30 mL/min) and were subjected to boluses (injected in 1-8 seconds) of purely nonionic media: mannitol and iohexol (in hyposmolal, isosmolal, and twice isosmolal forms) and iodixanol (in a hyposmolal form).

RESULTS

All contrast media elicited a dose-dependent increase in aortic pressure and contractile variables that was attenuated by an increased osmolality. Elevation of aortic pressure was followed by an increase in left ventricular systolic pressure and, with iodixamol and iohexol, a subsequent elevation of left ventricular end-diastolic pressure. Moderate hypothermic solutions (29 degrees C) did not alter the responses. The ionic washout profile was the same for the three substances, as were the individual washout profiles for sodium, potassium, chloride, magnesium, and calcium.

CONCLUSION

An increase in osmolality attenuates the increased contractility induced by a purely nonionic medium. A viscosity-induced rise in perfusion pressure may increase contractility. A moderate reduction in bolus temperature does not alter the contractile responses. The ionic washout profile is the same for the main cardioactive electrolytes.