Postoperative inflammatory response after autologous and allogeneic blood transfusion

BACKGROUND

Allogeneic blood transfusions cause immunosuppression. The aim of this study was to determine whether complement anaphylatoxins, cytokines, or both are released in the recipient, after blood transfusions in general, and after autologous blood transfusions in particular.

METHODS

Thirty-one patients having total hip joint replacement surgery were randomized to receive either allogeneic red blood cells (n = 15) or predeposited autologous whole blood transfusion (n = 16). Plasma concentrations of the anaphylatoxins C3a and C5a, the terminal C5b-9 complement complex, and cytokines IL-6 and IL-8 in the recipients were repeatedly analyzed before, during, and after surgery.

RESULTS

Significantly increased concentrations of IL-6 and IL-8 appeared in both groups, with a significantly greater increase in the autologous blood group. Patients in both groups developed a moderate but significant increase of C3a without a significant difference between them. C5a and terminal C5b-9 complement complex were not greatly changed.

CONCLUSIONS

The study showed a greater increase in cytokine concentration after autologous blood transfusion than after allogeneic blood transfusion. The lower response in the latter may result from transfusion-induced suppression of cellular immunity.

Null mutation in the desmin gene gives rise to a cardiomyopathy

A null mutation in the desmin gene has been introduced into the germ line of mice. Such mice develop and reproduce normally proving that desmin is not needed either for the formation of the heart or the alignment of functioning myofibrils. However, cardiovascular lesions and a skeletal myopathy were observed in growing and adult mice. In the present study we have carried out a detailed analysis of these cardiac lesions. Homozygous mutant mice, which were confirmed to lack expression of desmin mRNA and desmin protein in the heart, were revealed by electron microscopy to contain degenerating cardiomyocytes as early as 5 days post-partum. At 10 days post-partum and onwards the degeneration of cardiomyocytes gave rise to areas with an accumulation of macrophages, fibrosis and calcification preferentially in the inter-ventricular septum and the free wall of the right ventricle. The localization of the lesions mainly to these sites suggested that it is not the work load and contractions per se which were the pathogenic events leading to the cardiomyopathy. It might be that stress related to lengthening of the myocytes occur more in the right ventricle than in the left. At the ultrastructural level changes in the intercalated discs, disruption of the sarcolemma and supercontraction of myofibrils seemed to be the key events leading to cardiomyocyte death. Thus, the intermediate filaments are required to maintain the basic integrity of cardiomyocytes and especially the link between the intermediate filaments and the sarcolemma appear more important than previously realized.

A potential role of R-cadherin in striated muscle formation

We have examined the murine embryonic expression pattern of the cell adhesion molecule R-cadherin in muscle, kidney, thymus, and lung. In developing muscle, R-cadherin was first seen at 10.5-11.5 days postcoitum in the somitic myotome. Consistently, we found R-cadherin expressed at the highest levels in the myotome, early skeletal muscle, and smooth muscle (both vascular and visceral), while very low levels of R-cadherin were detected in the heart. The expression pattern and subcellular localization of R-cadherin in developing skeletal muscle indicate a possible role in myoblast cell-cell interactions during both primary and secondary myogenesis. In the developing kidney, R-cadherin was first detected at 10.5 days postcoitum in the mesonephric epithelial tubule cells. In the metanephric kidney, it was specifically expressed in the pretubular aggregates, comma- and S-shaped bodies, proximal tubules, and collecting ducts. Thus, in the kidney, R-cadherin was associated with the mesenchymal-epithelial transition. R-cadherin was also found in other developing epithelia, for example in the thymic epithelial cells. In the lung, R-cadherin was expressed at the highest levels in the smooth muscle surrounding the lung epithelial tubules. To test whether R-cadherin can direct formation of tissues, we constitutively expressed R-cadherin in E-cadherin-/- ES cells and examined histogenesis in teratomas derived from these cells. R-cadherin exclusively rescued formation of striated muscle and epithelia in the teratomas. R-cadherin's ability to form epithelia in vivo was substantiated by its ability to rescue formation of cystic embryoid bodies in vitro. By comparing our data with the previously reported embryonic expression patterns and histogenetic activities of E- and N-cadherin, we suggest that R-cadherin plays an important role in the formation of striated muscle and possibly also of epithelia.

Electrophysiological characterization of the prokinetic agents cisapride and mosapride in vivo and in vitro: implications for proarrhythmic potential?

In the present study the electrophysiological characteristics and the proarrhythmic potential of cisapride and a structurally related drug, mosapride, were compared. In the anesthetized guinea pig, cisapride and d-sotalol (0.01-10 micromol/kg i.v., n = 6) dose-dependently prolonged the duration of the monophasic action potential recorded from the left ventricle. The maximal lengthening was 18 +/- 3.2% at 1.0 micromol/kg (mean +/- S.E.M., P < .01 vs. base line) and 19 +/- 2.5% at 10 micromol/kg (P < .001) for cisapride and d-sotalol, respectively. In contrast, mosapride did not increase this variable. In a rabbit model of the acquired long QT syndrome, infusion of cisapride (0.3 micromol/kg/min for 10 min maximum, n = 6), but not mosapride or vehicle, was associated with a significant lengthening of the QTU interval (43 +/- 3.8 ms, P < .01). Furthermore, torsades de pointes appeared in two of the six rabbits given cisapride. In isolated rabbit Purkinje fibers (PF), cisapride increased the action potential duration (48 +/- 5.6% at 0.1 micromol/l, P < .01 vs. control, n = 4). Mosapride did not significantly influence the action potential duration (3 +/- 2.0% increase at 1.0 micromol/l, n = 6). However, after mosapride was washed out, the addition of cisapride (0.1 micromol/l) caused a 46 +/- 3.2% lengthening of the action potential duration (P < .01 vs. 1.0 micromol/l mosapride). Early afterdepolarizations and triggered activity appeared in four of eight cisapride-superfused PF stimulated at a very low frequency (0.1 Hz). In isolated rabbit cardiomyocytes, cisapride concentration-dependently blocked (IC50 = 9 nmol/l) the rapid component of the delayed rectifying K+ current (I(Kr)). Mosapride was approximately 1000-fold less potent in blocking I(Kr) (IC50 = 4 micromol/l). It is concluded that the electrophysiological characteristics of cisapride may explain the recently reported propensity to prolong the QT interval and to induce torsades de pointes in susceptible patients, although a structurally related benzamide, mosapride, did not appear to have electrophysiological features of relevance for induction of torsades de pointes in common with cisapride.

Growth hormone (GH) assays: influence of standard preparations, GH isoforms, assay characteristics, and GH-binding protein

The impact of the adoption of the new biosynthetic growth hormone (GH) WHO International Reference Preparation (IRP 88/624), and the recommendation to report results in microgram/L instead of mU/L, is described. Conversion factors were determined by comparing both the linear and nonlinear relations of the GH values. The Pharmacia polyclonal IRMA (p-IRMA) and the DELFIA monoclonal time-resolved immunofluorometric assay (trIFMA) with kit calibrators calibrated either against the pituitary-derived WHO IRP 80/505 or the new 88/624 were evaluated. Conversion factors of 4.17 mU/L = 1 microgram/L for the p-IRMA and 4.31 mU/L = 1 microgram/L for the trIFMA were necessary. Different cross-reactivity patterns for the deaminated and dimer 22-kDa, 20-kDa, and 17-kDa GH isoforms were found. Expected GH recovery was similar when the measured values were adjusted according to the results of the cross-reactivity study.

A Bone-Anchored Percutaneous Connector System for Neural Prosthetic Applications

A percutaneous connector system has been developed for use in neural prosthetic applications. It is based on a skin-penetrating, bone-anchored titanium pedestal, housing an 11-channel electrode array. Initial applications for the system are in audiology and, as such, the proposed fixture site is in the temporal bone.

The titanium pedestal is based on existing design features of the EPI Bioglass® implant, developed by University College London (UCL), and the Brånemark System®, employed by Nobel Biocare AB. The electrode array, consisting of platinum wires in a silicone carrier, can be custom designed to suit the application. The design features of the connector system are reviewed.

Animal studies have been used to assess soft tissue reactions and the osseointegration of the pedestal. The histological data are presented. The pedestal, electrode array and the mating external connector are currently undergoing mechanical and electrical testing.

The percutaneous connector system will undergo clinical trials, initially in the study of tinnitus (employing stimulation via an extracochlear electrode), and as part of a cochlear implant system (using a multichannel intracochlear electrode array and digital signal processing techniques).

A bone-anchored percutaneous connector system for neural prosthetic applications

A percutaneous connector system has been developed for use in neural prosthetic applications. It is based on a skin-penetrating, bone-anchored titanium pedestal, housing an II-channel electrode array. Initial applications for the system are in audiology and as such, the proposed fixture site is in the temporal bone. The titanium pedestal is based on existing design features of the EPI Bioglass implant, developed by University College London (UCL), and the Brånemark System, employed by Nobel Biocare AB. The electrode array, consisting of platinum wires in a silicone carrier, can be custom designed to suit the application. The design features of the connector system are reviewed. Animal studies have been used to assess soft tissue reactions and the osseointegration of the pedestal. The histological data are presented. The pedestal, electrode array and the mating external connector are currently undergoing mechanical and electrical testing. The percutaneous connector system will undergo clinical trials, initially in the study of tinnitus (employing stimulation via an extracochlear electrode), and as part of a cochlear implant system (using a multichannel intracochlear electrode array and digital signal processing techniques.

Motility stimulant effects of prostasome inclusion in swim-up medium on cryopreserved human spermatozoa

The chance of obtaining a fertilization and establishing a pregnancy increases with the number of motile spermatozoa that can reach and interact with the oocyte after the time of insemination. In an attempt to increase the recovery of freeze-thawed and motile spermatozoa, the swim-up medium was supplemented with prostasomes and some other effectors. Swim-up media supplemented with prostasomes were superior in comparison to the other effectors investigated in the recovery of motile spermatozoa for insemination. These results suggest that prostasome inclusion in swim-up medium might be of benefit in improving results in assisted reproductive technologies using freeze-thawed spermatozoa.

Myringotomized mice develop myringosclerosis in the pars flaccida and not in the pars tensa

The development of myringosclerosis has been correlated with increased production of oxygen-derived free radicals. For the present study, we used a null mutant mouse lacking extracellular superoxide dismutase to test the hypothesis that increased production of free radicals can cause the development of myringosclerosis. Null mutant mice and wild-type, control mice were myringotomized and kept in ambient air for 3 weeks. Both groups developed myringosclerosis in the pars flaccida, but not in the pars tensa. The sclerotic lesions were visible in both the light and the electron microscope but not in the otomicroscope. In particular, the localization of the sclerotic deposits was found beneath both the inner and outer epidermal epithelium. No difference concerning the extent or number of sclerotic lesions between the null mutant and the wild-type mice could be distinguished.

Targeted disruption of the V(H) 81X gene: influence on the B cell repertoire

We have generated a mutant mouse in which the most D-proximal V(H) gene (V(H)81X) has been disrupted by introducing a neomycin-resistance gene into the V(H)81X exon by means of gene targeting in embryonic stem cells. The mutant mice generated are unable to express the V(H)81X gene but appear to display a normal pattern of B cell differentiation as well as normal numbers of bone marrow and peripheral B cells from fetal life all through ontogeny. They mount normal immune responses to several different antigens tested. In contrast, the distribution of V(H) gene rearrangements in the V(H)7183 family is altered in homozygous mutant mice. Thus, the antibody repertoire of the targeted mice is modified, at least as far as the expression of V(H)7183 genes is concerned.

Characterisation of the effects of cadmium on the release of calcium and on the activity of some enzymes from neonatal mouse calvaria in culture

Exposure to cadmium (Cd) causes skeletal impairments, such as osteoporosis and osteomalacia, in many mammalian species, including humans. There is, however, some controversy about the mechanism of action of these Cd-induced skeletal effects, although both a direct influence on bone cells and effects that are secondary to renal damage caused by the metal have been demonstrated. In the present study, we cultured calvarial bones from neonatal mice and exposed them to Cd to study the effects of the metal on calcium release and on the activity of some enzymes of importance for bone resorption and bone formation. Cd dose-dependently stimulated calcium release from the bones. Maximal release was noted at Cd concentrations of 0.4-0.8 microM, which was similar to the level of release in the presence of maximal stimulatory concentrations of parathyroid hormone (10 nM) and prostaglandin E2 (10 microM). Cykloheximide (1 microM) inhibited calcium release elicited by Cd, prostaglandin E2 and parathyroid hormone. Cd-induced calcium release was linearly increased from 24 to 72 hr of culture. Production of prostaglandin E2 by the bone specimens was dose-dependently stimulated by Cd and inhibited by 1 microM indomethacin. Cd-induced calcium release was inhibited by acetazolamide (100 microM), indomethacin (1 microM) and ibuprofen (10 microM). Prostaglandin E2-stimulated calcium release was not inhibited by indomethacin. Exposure to 32 microM Cd, present during a 48-hr incubation period, significantly decreased prostaglandin E2-stimulated calcium release from 38.9% to 29.8%. Calcium release induced by parathyroid hormone was more sensitive to inhibition by the metal (i.e., Cd concentrations of 0.2 and 32 microM decreased the release from 37.7% to 31% and 19%, respectively). Cd present in the culture medium during a 48-hr incubation dose-dependently inhibited the activity of alkaline phosphatase and tartrate-resistant acid phosphatase in the bones but did not influence the activity of carbonic anhydrase. We conclude that Cd has a direct stimulatory effect on bone resorption, and this effect is dependent on prostaglandin production and also on protein synthesis. On the other hand, Cd also has an inhibitory effect on bone resorption (i.e., resorption is inhibited by higher concentrations of the metal). Moreover, Cd may impair bone formation by impeding the activity of alkaline phosphatase.

Lidocaine and nisoldipine attenuate almokalant-induced dispersion of repolarization and early afterdepolarizations in vitro

INTRODUCTION

Treatment with Class III antiarrhythmic agents may lead to increased dispersion of repolarization and early afterdepolarizations (EADs), which are both likely substrates for torsades de pointes. Recent studies in vivo have shown that the prevalence of proarrhythmias induced by Class III agents may be reduced by Na(+)- or Ca(2+)-blocking agents. In the present study, tentative mechanisms for this protective effect were investigated in vitro.

METHODS AND RESULTS

Transmembrane action potentials were recorded simultaneously from rabbit isolated ventricular muscle (VM) and Purkinje fibers (PF). At a basic cycle length (BCL) of 500 msec, the Class III agent almokalant (0.1 microM) increased the dispersion by prolonging the action potential duration (APD) significantly more in the PF (33% +/- 4.2%, n = 18) than in the VM (17% +/- 5.9%, n = 18, P < 0.05). In six of the preparations, addition of 1, 5, and 25 microM lidocaine reduced the almokalant-induced prolongation in a concentration-dependent manner mainly in the PF, thereby decreasing the dispersion. At 5 microM lidocaine, the remaining prolongation was 7% +/- 12.2% (P < 0.05 vs time controls) in the PF and 14% +/- 6.4% in the VM, respectively. In six other preparations, the addition of 0.01, 0.05, and 0.25 microM nisoldipine did not reduce the almokalant-induced prolongation in the PF and VM, but attenuated the spike-and-dome appearance of the action potential in the PF. In separate experiments performed at a BCL of 1000 msec, EADs developed in 2 of 6 and 5 of 6 PF during superfusion with almokalant (0.3 and 1 microM, respectively) at an APD of 828 +/- 41.4 msec. In six separate preparations pretreated with lidocaine (5 microM), the almokalant-induced prolongation in the PF was less pronounced and EADs were not observed. Pretreatment with nisoldipine (0.05 microM) did not influence the response to almokalant, and in 4 of 6 preparations the APD exceeded 1000 msec. Despite this extensive prolongation, EADs did not appear.

CONCLUSION

At concentrations that did not affect the APD in the VM but reduced the APD in the PF, lidocaine suppressed almokalant-induced dispersion and the development of EADs. Nisoldipine, on the other hand, inhibited almokalant-induced EADs directly. Hence, the primary APD-prolonging effect of a Class III agent may be preserved, but the risk of proarrhythmias reduced, during concomitant treatment with low concentrations of a Na(+)- or Ca(2+)-blocking agent.

Rhythm anomalies related to delayed repolarization in vivo: influence of sarcolemmal Ca++ entry and intracellular Ca++ overload

The present study examined how Ca++ entry and intracellular Ca++ overload may contribute to the appearance of torsades de pointes in the setting of delayed repolarization. In anesthetized rabbits, the infusion of methoxamine and the selective I kappa s blocker almokalant (8.8 micrograms/kg.min) was associated with a lengthening of the QTU interval (37 +/- 2.6 ms, P < .001) and the appearance of torsades de pointes in 9/10 rabbits. In rabbits pretreated with nisoldipine (7.7 or 37 micrograms/kg i.v.), the incidence of almokalant-induced torsades de pointes was reduced to 7/10 (P = .5820 vs. vehicle) and 1/10 (P = .0006) rabbits, respectively. This occurred without attenuating the QTU-prolonging effect of almokalant (47 +/- 7.0 ms and 56 +/- 8.6 ms, respectively). Likewise, pretreatment with flunarizine (0.5 or 3.0 mg/kg i.v.) reduced the incidence to 1/6 (P = .0076) and 0/6 animals (P = .0009), respectively. In 10 of the rabbits that were given nisoldipine or flunarizine and did not experience torsades de pointes with almokalant, BAY K 8644 (0.11 mg/kg) was injected. In six of these rabbits, BAY K 8644 promptly induced torsades de pointes. In four vehicle-pretreated rabbits that experienced torsades de pointes with almokalant, acute injection of nisoldipine (37 micrograms/kg) abruptly suppressed the proarrhythmia. In separate experiments, rabbits were treated with ryanodine or BAPTA-AM and were subsequently administered almokalant. Compared with the vehicle-pretreated rabbits, these interventions did not significantly reduce the incidence of torsades de pointes (from 6/5 rabbits to 3/8 and 3/8 rabbits, respectively, P = .1776). The results demonstrate that Ca++ entry through the L-type Ca++ channel may be of crucial importance for the induction of torsades de pointes in the acquired long QT syndrome.

Accuracy of machine milling and spark erosion with a CAD/CAM system

A method for manufacturing crowns and fixed partial dentures based on CAD/CAM has been developed as an alternative to the lost wax technique and the casting of an alloy. In this process two steps are included: milling and spark erosion. The computer-assisted design (CAD) relies heavily on the accuracy of the milling and spark erosion processes to achieve a clinically acceptable restoration. These two processes must be able to produce the crown data generated in the CAD files. This study evaluated the accuracy of the Procera CAD/CAM system in creating specific geometric bodies that were compared with the known dimensions in the CAD files for these bodies. The manufacturing errors of milling (ellipse +/- 6.5 microm, square +/- 3.4 microm, and cylinder +/- 5.8 microm) and spark erosion (ellipse +/- 8.6 microm and square +/- 10.4 microm) were determined. The accuracy of this manufacturing process demonstrated that this system was capable of producing a crown with a clinically accepted range for marginal opening gap dimension of less than 100 microm.

Electrophysiological and inotropic characterization of a novel class III antiarrhythmic agent, GLG-V-13, in the mammalian heart

GLG-V-13, a novel 3,7-diheterabicyclo(3.3.1)nonane, was examined both in vivo and in vitro to characterize its electrophysiological, hemodynamic, and inotropic properties. In anesthetized guinea pigs, GLG-V-13 [0.5-500 micrograms/kg intravenously (i.v.), n = 6] lengthened the epicardial monophasic action potential (MAP) duration, the atrioventricular (AV) conduction time and the RR interval in a dose-dependent manner. At the highest dose, these variables were increased by 30, 13, and 23%, respectively. No significant effects were noted on QRS duration or blood pressure (BP). In rabbit atrial and papillary muscle preparations, GLG-V-13 (0.32-3.2 mg/L) did not exert a negative inotropic action and in isolated rabbit cardiomyocytes the agent blocked the rapidly activating delayed rectifier K+ current (IKr, EC50 = 48 micrograms/L). In 10 intact anesthetized mongrel dogs, the left ventricular (LV) endocardial MAP was measured during atrial pacing before and after administration of GLG-V-13 (3 and 6 mg/kg i.v.). As compared with the drug-free state, the agent induced a significant prolongation of the MAP at all pacing frequencies (2.0-4.5 Hz). In 15 anesthetized dogs studied 1-4 days after two-stage ligation of the left anterior descending coronary artery (LAD), the antiarrhythmic/proarrhythmic potential of GLG-V-13 was compared with that of lidocaine. ECG, His bundle, LV (IZepi), and composite and normal zone composite electrograms were recorded. Programmed electrical stimulation (PES) and burst pacing (4.0-7.0 Hz) were delivered to the right ventricular outflow tract. In the drug-free state, sustained monomorphic ventricular tachycardia (SMVT) was inducible in 6 dogs (6 of 15). After lidocaine, SMVT was induced in 7 other dogs (13 of 15). GLG-V-13 prevented induction of SMVT in 5 of 6 dogs; a proarrhythmic action was noted in 1 dog only. GLG-V-13 slowed the heart rate (HR), increased the AH and the HV intervals, prolonged the paced (2.5 Hz) QT interval, and increased the ventricular effective refractory period (VERP). These effects were associated with 2:1 block of late potentials in the IZepi electrograms, a phenomenon also observed during rapid atrial pacing (2.5-3.5 Hz), suggestive of a marked prolongation of refractoriness in the ischemically damaged myocardium. In light of the recent Cardiac Arrhythmia Suppression Trial (CAST) study, the antiarrhythmic efficacy, together with the low proarrhythmic potential and lack of cardiodepressant properties of GLG-V-13, may merit further investigation of this novel class III antiarrhythmic agent.

Measuring fit at the implant prosthodontic interface

Four centers in the United States and Sweden have been working for 2 years to develop systems and methods for measuring fit at the prosthodontic interface. Two systems are based on stylus contact techniques, one system uses a laser as its reader source, and one system is photogrammetric. All the systems are capable of providing data as three-dimensional x, y, and z axes coordinate values that can be transformed into linear and angular data that characterize the bearing surfaces of abutments or abutment replicas and their mating components in the prosthesis framework. The centroid, a single point computed from the collected data, was the measurement unit, derived for these bearing surfaces, that was used to compare the systems. All four methods can most likely detect misfits that are relevant in the clinical setting; however, only one system can be used intraorally. When any measurement system is assessed, the data should always be examined for repeatability to establish the reliability of the system. This investigation made comparisons among the measurement methods used at the four centers. It was apparent from this study that comparisons of data from measurement systems should be rounded to the nearest 10 microns. The SDs determined in the comparisons were larger than 5 microns and therefore misfits should be calculated in terms smaller than 10 microns. This final point is important to the clinician who relies on research reports about precision of fit when selecting treatment approaches in caring for the implant prosthodontic needs of their patients.

Prevention of class III-induced proarrhythmias by flecainide in an animal model of the acquired long QT syndrome

The influence of the class Ic agent, flecainide, on the incidence of class III-induced torsades de pointes was examined in an animal model of the acquired long QT syndrome. Twenty-four chloralose-anaesthetized rabbits were pretreated at random with flecainide or vehicle and subsequently given a concomitant infusion of methoxamine and the class III antiarrhythmic agent almokalant. In seven out of eight vehicle-treated rabbits, almokalant induced torsades de pointes which was preceded by a significant lengthening of the JTU interval (used as an indirect measure of ventricular repolarization time) by 55 +/- 9.2 msec. Flecainide dose-dependently reduced the incidence of almokalant-induced torsades de pointes. Hence, in a group of rabbits given a low dose (0.14 mumol/kg + 1.4 mumol/kg/hr) of flecainide, four out of eight animals experienced torsades de pointes (P = 0.1538 versus vehicle) whereas no case (n = 8) was observed after a higher dose (4.8 mumol/kg + 4.8 mumol/kg/hr, P = 0.0007). In the former group almokalant induced a maximal increase in the JTU interval not differing from that seen in the vehicle-treated group (58 + 12.1 msec, P > 0.05). Pretreatment with the high dose of flecainide, however, caused a significant attenuation of the almokalant-induced lengthening of the JTU interval (18 +/- 6.5 msec. P < 0.05). It is concluded that flecainide reduces the risk of proarrhythmia in the setting of delayed repolarization partially by attenuating the primary electrophysiological effect of class III agents.

Expression of Fc gamma RIII defines distinct subpopulations of fetal liver B cell and myeloid precursors

We have isolated four distinct fetal liver (FL) populations based on the expression of AA4.1 and the low-affinity Fc gamma receptors type II and III (Fc gamma RII/III), and characterized them with respect to B cell, T cell, and myeloid precursor content. Polymerase chain reaction analysis revealed that the prevalent Fc gamma R isoform at this stage of FL development (day 12 of gestation) was Fc gamma RIII. Two of the four populations, one which expressed AA4.1 but little if any Fc gamma RII/III (AA4.1+), and one which expressed abundant levels of both markers (AA4.1+/FcR+), contained B cell precursors that grew and differentiated to generate VHDJH-rearranged B-lineage cells on S-17 stromal cells in the presence of IL-7. When cultured on FLST2 stromal cells only the AA4.1+ cells generated VHDJH-rearranged B-lineage cells. T cell precursors as assayed by their ability to repopulate fetal thymi in organ culture were found only in the AA4.1+ fraction. In contrast to the lymphoid precursors, myeloid precursors able to generate colonies in methyl cellulose cultures were found in all four fractions including the one which expressed Fc gamma RII/III but no AA4.1 (FcR+) and the one which expressed neither marker (AA4.1-/FcR-). The AA4.1+ population which contained both B cell and T cell precursors was enriched for precursors from many myeloid lineages including the most immature ones which generated multilineage colonies. In contrast, the AA4.1+/FcR+ population, which also contained B cell precursors, was almost devoid of myeloid precursors and the few that were detected were committed to the macrophage lineage. The population defined as FcR+ was also enriched for precursors; however, the majority of these were committed to the erythroid, the macrophage and the mast cell lineage. The fourth population which expressed neither marker (AA4.1-/FcR-) was enriched for relatively mature erythroid precursors which were not present in any of the other fractions. Together, these findings demonstrate that fractionation of FL cells on the basis of AA4.1 and Fc gamma RII/III expression distinguishes subpopulations of B cell and myeloid precursors and suggests that the low-affinity Fc gamma RIII could play a role in the development of early hematopoietic cells at this stage of ontogeny.

Roentgen stereophotogrammetric analysis as a predictor of mechanical loosening of knee prostheses

The tibial components in 143 patients with total knee replacements performed before 1988 were assessed for micromotion using roentgen stereophotogrammetric analysis (RSA) over a period of 13 years. The fixation of the prostheses remained clinically sound in all cases, although revision had been required for other reasons in seven. In a second group taken from all cases with RSA available on our full database to 1990, 15 tibial components had been followed by RSA from the insertion until, 1 to 11 years after the initial arthroplasty, they were revised for mechanical loosening of the tibial component; 12 of these comprised all the loosenings in the base group, thus making a total of 155 consecutive cases, while an additional three were inserted after the base material had been compiled. The mean migration in the first group was about 1 mm at one year, but subsequent migration was slower, reaching a mean of about 1.5 mm after ten years. About one-third migrated continuously throughout follow-up, while two-thirds ceased to migrate after one to two years. In the revision group, 14 components had migrated continuously and at one year significantly more than those in the first group. One revision case lacked the crucial one-year follow-up and could not be classified. These findings suggest that mechanical loosening begins early in the postoperative period. Clinical symptoms which necessitate revision, seen at this stage in 20% of abnormally migrating tibial components, may not appear until up to ten years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Roentgen stereophotogrammetric analysis as a predictor of mechanical loosening of knee prostheses

The tibial components in 143 patients with total knee replacements performed before 1988 were assessed for micromotion using roentgen stereophotogrammetric analysis (RSA) over a period of 13 years. The fixation of the prostheses remained clinically sound in all cases, although revision had been required for other reasons in seven. In a second group taken from all cases with RSA available on our full database to 1990, 15 tibial components had been followed by RSA from the insertion until, 1 to 11 years after the initial arthroplasty, they were revised for mechanical loosening of the tibial component; 12 of these comprised all the loosenings in the base group, thus making a total of 155 consecutive cases, while an additional three were inserted after the base material had been compiled. The mean migration in the first group was about 1 mm at one year, but subsequent migration was slower, reaching a mean of about 1.5 mm after ten years. About one-third migrated continuously throughout follow-up, while two-thirds ceased to migrate after one to two years. In the revision group, 14 components had migrated continuously and at one year significantly more than those in the first group. One revision case lacked the crucial one-year follow-up and could not be classified. These findings suggest that mechanical loosening begins early in the postoperative period. Clinical symptoms which necessitate revision, seen at this stage in 20% of abnormally migrating tibial components, may not appear until up to ten years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

A specific and sensitive method for the determination of linamarin in Urine

A method is described for the quantitative determination of the cyanogenic glycoside linamarin. A preseparation procedure for urine samples was necessary to remove interfering substances. This was done by solid-phase extraction on a silica column containing cyclohexyl functional groups, which retained linamarin but allowed thiocyanate to pass unrestricted through the column. After elution of linamarin from the column by 35% (v/v) aqueous methanol, the glycoside was quantified following enzymatic hydrolysis, using the specified enzyme linamarase, and the free cyanide thus liberated was estimated spectrophotometrically. This method allowed quantification of linamarin in urine down to 10 mumol/l, with an estimated recovery of 91%. In 75 Tanzanian subjects consuming insufficiently processed cassava, the mean (+/- SD) urinary linamarin concentration was 104 (+/- 104) mumol/l (range 0 - 644 mumol/L), while that for thiocyanate was 486 (+/- 451) mumol/l (range 10-2,940 mumol/l), giving an approximate 1:5 molar concentration ratio between urinary linamarin and thiocyanate.

Insulin-promoter-factor 1 is required for pancreas development in mice

The mammalian pancreas is a mixed exocrine and endocrine gland that, in most species, arises from ventral and dorsal buds which subsequently merge to form the pancreas. In both mouse and rat the first histological sign of morphogenesis of the dorsal pancreas is a dorsal evagination of the duodenum at the level of the liver at around the 22-25-somite stage, and shortly thereafter a ventral evagination appears as a derivative of the liver diverticulum. Low levels of insulin gene transcripts are already present and restricted to the dorsal foregut endoderm at 20 somites, suggesting that pancreas- or insulin gene-specific transcriptional factors are present in this region before the onset of morphogenesis. Insulin-promoter-factor 1 (IPF1) is a homeodomain protein which, in the adult mouse pancreas, is selectively expressed in the beta-cells and binds to and transactivates the insulin promoter. In mouse embryos, IPF1 expression is restricted to the developing pancreatic anlagen and is initiated when the foregut endoderm is committed to a pancreatic fate. We now show that mice homozygous for a targeted mutation in the Ipf1 gene selectively lack a pancreas. The mutant pups survive fetal development but die within a few days after birth. The gastrointestinal part and all other internal organs were normal in appearance. No pancreatic tissue and no ectopic expression of insulin or pancreatic amylase could be detected in mutant embryos and neonates. These findings show that IPF1 is needed for the formation of the pancreas and suggest that it acts to determine the fate of common pancreatic precursor cells and/or to regulate their propagation.

Assay systems for the growth hormone-binding protein

The first method used for detection of growth hormone-binding protein (GHBP) in biological fluids was based on the incubation of the sample with radiolabeled GH followed by separation of bound and free GH by gel exclusion chromatography. Recently, other methods have been developed which are faster and easier to use. These methods include variants of the original binding/column assay (e.g., separation of bound and free GH is obtained by immunoprecipitation, charcoal adsorption, ion exchange chromatography, or HPLC), and a ligand-mediated immunofunctional assay (LIFA), in which a monoclonal antibody is used to capture the GHBP on a microtiter plate; all binding sites are saturated with GH and an anti-GH antibody is used to detect the amount of GH (endogenous and exogenous) bound to the GHBP. To permit comparison of results obtained by different methods we have cross-validated the LIFA with two different binding assays: (i) the original long column assay (column assay), and (ii) an assay based on immunoprecipitation (RIPA) of the GH/GHBP complex with an anti-GHBP antibody.

A gene family encoding heterogeneous histone H1 proteins in Trypanosoma cruzi

A gene family encoding a set of histone H1 proteins in Trypanosoma cruzi is described. The sequence of 3 genomic and 4 cDNA clones revealed the presence of several motifs characteristic of histone H1, although heterogeneity at the polypeptide level was evident. The clones encode histone H1 proteins of an unusually small size (74-97 amino acids), which lack the globular domain found in histone H1 of higher eukaryotes. All histone H1 mRNAs from T. cruzi are polyadenylated, although no typical polyadenylation signal was found. Furthermore, the genes encoding the histone H1 proteins in T. cruzi are found in a tandem array containing 15-20 gene copies per haploid genome. This tandem array is located on a large chromosome of 2.2 Mb.

Analysis of the cyanogenic glycoside linamarin in urine by isotachophoresis

A separation system based on isotachophoresis is described for the cyanogenic glycoside linamarin in aqueous solution and in human urine. Isotachophoresis is a migration of a substance in an electric field, which is applied to a system of electrolytes of specific design. Detection is carried out by monitoring conductivity changes. However, for linamarin in urine, a preseparation procedure was necessary because of the high amount of electrolytes. This was performed by affinity chromatography on a silica sorbent column, with cyclohexyl as the functional group by which linamarin was retained. After elution from the column by methanol, a separation and quantitation of linamarin was possible by means of isotachophoresis. The method allowed determinations of urinary linamarin exceeding 100 microM, with a coefficient of variation of 13% at 500 microM.

Induction of rhythm abnormalities in the fetal rat heart. A tentative mechanism for the embryotoxic effect of the class III antiarrhythmic agent almokalant

OBJECTIVES

The aim was to test the hypothesis that the recently reported embryotoxic effect of class III antiarrhythmic agents may be a result of electrophysiological disturbances induced by these agents.

METHODS

Comparative studies of drug effects in the adult and fetal rat were performed using three experimental models: (1) effects of almokalant upon pregnancy and fetal mortality in rats given daily doses of 0, 10, 50, 100, or 400 mumol.kg-1 orally in the diet on days 6-15 of pregnancy; (2) effects of d-sotalol (1-1000 microM), almokalant (0.1-100 microM) and dofetilide (0.01-10 microM) on the adult and fetal cardiac action potential in vitro; (3) voltage clamp recordings in single fetal and adult ventricular myocytes superfused with almokalant (0.5 microM).

RESULTS

In the groups of rats treated with 100 and 400 mumol.kg-1, respectively, the body weight gain was decreased from day 12 of gestation, and there were no viable fetuses at termination of pregnancy. In atrial as well as ventricular tissue, the class III agents induced a concentration dependent prolongation of the fetal action potential duration, accompanied by a reduction in heart rate and eventually the appearance of rhythm abnormalities and/or early afterdepolarisations. The adult action potential duration remained unaffected. An almokalant sensitive current (probably the delayed rectifier, IK) could be evoked both in the fetal and in the adult ventricular cells.

CONCLUSIONS

Class III antiarrhythmic agents were shown to induce fetal mortality and rhythm abnormalities in the rat heart. Although they do not prove a causal relationship between these effects, our observations may have implications for the clinical use of class III antiarrhythmic agents in women of childbearing potential.

Bone response to hydroxyapatite-coated and commercially pure titanium implants in the human arthritic knee

Rough and smooth commercially pure (c.p.) titanium implants and hydroxyapatite-coated (HA-C) implants were inserted in arthritic human knees and left in situ in order to compare the response of bone to these three implants. Radiographic examination alone could not determine if bone apposition had occurred. After 3 and 6 months, histomorphometric analyses of undecalcified sections, 10 microns thick, revealed a statistical significance in the amount of bone apposition to rough-surfaced and HA-C implants as compared with smooth uncoated implants. Most of the rough-surfaced c.p. titanium implants and the HA-C implants had achieved bone apposition on the order of 50%. No statistically significant differences in apposition were seen between the rough-surfaced and HA-C implants. The smooth c.p. titanium implants were mostly encapsulated in fibrous tissue.

Proarrhythmic effects of the class III agent almokalant: importance of infusion rate, QT dispersion, and early afterdepolarisations

OBJECTIVE

The aim was to study factors contributing to torsade de pointes in the acquired long QT syndrome.

METHODS

Anaesthetised rabbits or cats were given a continuous infusion of methoxamine and the class III agent almokalant (at a rate of 5 or 25 nmol.kg-1.min-1, respectively) and the effects on incidence of torsade de pointes and QT dispersion were examined. Effects of almokalant on action potentials recorded from Purkinje fibres and ventricular cells of rabbits and cats were also studied.

RESULTS

"High rate" infusion of almokalant prolonged the QTc interval [from 162(SEM 6.2) ms to 211 (5.3) ms, p < 0.001] and initiated torsade de pointes in 9/10 rabbits after a dose of 391(116.3) nmol.kg-1. During "low rate" infusion, 1/8 rabbits developed torsade de pointes (p = 0.0029) despite infusion of 900 nmol.kg-1 almokalant and QTc prolongation from 162(3.6) ms to 230(12.6) ms (p < 0.01). In eight separate rabbits given the high rate infusion of almokalant, seven developed torsade de pointes and the QTc dispersion increased from 15(1.7) ms to 32(5.6) ms (p < 0.05). In six rabbits given the low rate infusion, none developed torsade de pointes (p = 0.0023), and the QTc dispersion was unaltered. In six cats, high rate infusion induced a QT interval lengthening from 241(6.0) ms to 349(8.0) ms (p < 0.001), but in only one cat was torsade de pointes initiated and preceded by a marked increase in QT dispersion (from 22 ms to 78 ms). In vitro, almokalant caused a marked lengthening of the action potential duration and early afterdepolarisations in Purkinje fibres but not in ventricular muscle cells of the rabbit. In the cat, however, almokalant induced a homogeneous prolongation of the action potential duration in both cell types, and early afterdepolarisations were never observed.

CONCLUSIONS

The rate of infusion of repolarisation delaying agents may influence the dispersion of repolarisation and play a decisive role in the initiation of torsade de pointes.

Attenuation of proarrhythmias related to delayed repolarization by low-dose lidocaine in the anesthetized rabbit

Polymorphous ventricular tachyarrhythmias (torsades de pointes) were induced in seven of eight (88%) anesthetized rabbits receiving the class III antiarrhythmic agent almokalant (25 nmol/kg/min i.v.). The tachyarrhythmia was preceded by a significant lengthening of the QT interval from 118 +/- 7.2 to 148 +/- 9.0 msec, P < .01. Two separate groups of eight rabbits in each were given lidocaine (4.3 mumol/kg + 12.8 mumol/kg/hr or 12.8 mumol/kg + 38.4 mumol/kg/hr), before almokalant was administered. In comparison with the vehicle-pretreated rabbits, lidocaine treatment caused a dose-dependent attenuation in the incidence of torsades de pointes. Hence, the incidence was reduced to four of eight (50%, P = .1538 vs. the vehicle-treated group) rabbits and to none of eight (0%; P = .0007) rabbits in the groups treated with the "low" and the "high" dose of lidocaine, respectively. This attenuation was observed despite a significant prolongation of the QT interval by almokalant (from 128 +/- 7.6 to 175 +/- 15.9 msec, P < .01, and from 116 +/- 8.4 to 159 +/- 10.3 msec, P < .001, respectively). Acute injection of lidocaine (12.8 mumol/kg, n = 4) during recurrent episodes of torsades de pointes in vehicle-treated rabbits caused an abrupt restoration of sinus rhythm without influencing the almokalant-induced prolongation of the QT interval. It is concluded that lidocaine may inhibit the initiation of and suppress rhythm abnormalities related to delayed repolarization.(ABSTRACT TRUNCATED AT 250 WORDS)

Embryonic stem cells express growth hormone receptors: regulation by retinoic acid

Embryonic and fetal growth are generally considered to be independent of pituitary GH. However, it has been demonstrated recently that 18-day-old rat embryos and rat fetuses express GH receptors, suggesting that GH could play a role in early development. The aim of the present investigation was to determine whether preimplantation embryos also express GH receptors. Germ line competent mouse embryonic stem (ES) cells and cultured mouse preimplantation embryos were examined with Northern blot analysis, RNAse-protection solution-hybridization assays, reverse transcription/polymerase chain reaction assays and immunohistochemistry for the detection of GH receptors. Northern blot analysis of ES cells using a probe corresponding to the extracellular domain of the GH receptor demonstrated the presence of two transcripts (1.2 and 4.5 kilobases). The RNAse-protection solution-hybridization assay revealed that ES cells express approximately one sixth of the GH-receptor messenger RNA (mRNA) levels expressed in liver from pregnant mice. Treatment of cultured ES cells with retinoic acid (100 nM) for 6 days increased GH-receptor mRNA levels (P < 0.01). GH-receptor mRNA was further identified in ES cells, preimplantation embryos, muscle, liver, and placenta by a reverse transcription/polymerase chain reaction assay. In humans it has previously been shown that exon 3 of the GH-receptor is deleted in the placenta. However, none of the studied mouse tissues had a deletion of the GH-receptor mRNA corresponding to exon 3 of the human GH receptor. GH-receptor immunoreactivity was identified on the cultured ES-cells by immunohistochemistry. In conclusion, we have in the present study shown that germline competent ES cells and preimplantation mouse embryos express the GH receptor transcript and that this transcription is increased by retinoic acid in ES cells. Furthermore, the presence of GH-receptor immunoreactivity on the ES cells indicates that the GH-receptor transcript is translated.

Two proteins involved in kinetoplast compaction

The kinetoplast is the genome of the single mitochondrion of trypanosomatid Protozoa, and contains up to 30% of total cellular DNA in a network of catenated AT-rich rings. EM studies show that the kinetoplast is organized into a compact, disc-shaped structure in vivo, but little is known about proteins involved in its architecture. Defining such proteins would be useful to understand the molecular biology of this unusual organelle and to design compounds to contain parasite growth. We show here that two proteins, p1 and p2 of M(r) approximately 22 and approximately 21 kDa, respectively, from the trypanosomatid Crithidia fasciculata can compact kDNA networks efficiently in vitro, the first such demonstration with purified trypanosome proteins. We show that these proteins are localized exclusively in the parasite's kinetoplast. Our data thus define two proteins potentially involved in kinetoplast organization in vivo.

Micromotion of a noncemented tibial component with screw fixation. An in vivo roentgen stereophotogrammetric study of the Miller-Galante prosthesis

Micromotion of the tibial component was studied in ten cases of successful arthroplasty for gonarthrosis using the Miller-Galante total knee prosthesis with roentgen stereophotogrammetric analysis (RSA). In six of seven cases, there was a mean of 0.6-mm migration during the first year. Most of this migration occurred as tilt and rotation. Subsidence was seldom found. Inducible displacement was observed in seven cases after one year; in six, deflections were found. In five cases, the inducible displacement was small, approximately 0.3 mm, whereas the sixth case showed inducible displacement of 1.7 mm. The micromotion found in this study was smaller than has previously been reported for other noncemented prostheses. In some of these cases, the RSA data may be compatible with mechanical coupling of the prosthesis to the bone by bony ingrowth.

Influence of sodium selenite on 203Hg absorption, distribution, and elimination in male mice exposed to methyl203Hg

To study the effects of long-term selenium supplementation on absorption, distribution, and elimination of methylmercury (MeHg) in mice, three groups of male mice (Balb/c CA) were exposed for 7 wk to 0, 0.6, and 3 ppm sodium selenite in tap water. They were then given a single oral dose of Me203Hg (2 mumol/kg) by gastric intubation, and elimination of 203Hg was followed by whole-body counting for 49 d at the same Se exposure as previously. Twenty-four hours and 49 d after dosage, 6-7 animals/group were sampled for analysis of 203Hg distribution in the body. Glutathione peroxidase (GSH-PX) activity in blood and selenium levels in the liver were used as measures of selenium status. Gastrointestinal absorption of Me203Hg was not influenced by the Se status of the animals. Selenium supplementation of MeHg-exposed mice caused an enhanced whole-body elimination of Hg, but selenium-supplemented animals did not have lower Hg levels in the brain and kidney than nonsupplemented animals. The effect of selenium on the accumulation of Hg in the brain was dose-dependent, a high dose (3 ppm Se) causing a higher initial accumulation of Hg. The intracellular distribution of 203Hg in the liver and kidney was not affected by Se. The results indicate that selenium treatment of MeHg-exposed mice may have a positive effect on the health of the animals by decreasing the total body burden of MeHg.

Growth hormone insensitivity associated with elevated circulating growth hormone-binding protein in children with Alagille syndrome and short stature

The purpose of this study was to assess GH sensitivity in children with Alagille syndrome (syndromic intrahepatic bile duct paucity) by examining their response to short term administration of recombinant human GH (rhGH). Serum levels of insulin-like growth factor-I (IGF-I) were low despite elevated overnight integrated serum GH concentrations. Administration of rhGH (0.05 mg/kg.day for 3 days) to four growth-retarded children with Alagille syndrome did not significantly alter the serum concentrations of IGF-I and insulin, blood urea nitrogen, or urinary calcium excretion. In contrast, circulating IGF-I increased 2-fold in two children with Alagille syndrome and normal stature. In the control group, consisting of seven prepubertal children with GH deficiency, the predicted changes in response to rhGH in serum concentrations of IGF-I and insulin, urea nitrogen, and urinary calcium excretion were observed. Serum GH-binding protein levels, measured by a ligand-mediated immunofunctional assay, were significantly higher in children with Alagille syndrome than in children with cirrhosis or GH deficiency. We conclude that growth-retarded children with Alagille syndrome are insensitive to GH. The growth disturbances and metabolic defects may be due in part to failure to increase IGF-I concentrations in response to GH, implying that growth-retarded children with Alagille syndrome may benefit from IGF-I treatment.

Electrophysiological and inotropic effects of H 234/09 (almokalant) in vitro: a comparison with two other novel IK blocking drugs, UK-68,798 (dofetilide) and E-4031

OBJECTIVE

The aim was to compare the electrophysiological and inotropic effects of the novel class III agents H 234/09, UK-68,798, and E-4031 in vitro.

METHODS

The electrophysiological effects were investigated by recording transmembrane action potentials in the isolated ventricular muscle and Purkinje fibres of the rabbit; effects on force (adjusted to the maximum isoprenaline response) and refractoriness were investigated in the isolated cat papillary muscle.

RESULTS

It was shown that all the drugs induced a concentration dependent prolongation of the action potential duration, which was much more pronounced in the Purkinje fibres than in the ventricular muscle. However, when compared at concentrations giving a 15% increase of the action potential duration in ventricular muscle, H 234/09 was significantly less effective in the Purkinje fibres than the other two drugs. In the cat papillary muscle all drugs induced an increase in force development. This increase tended to parallel the increase in effective refractory period. However, at prolongations of effective refractory period of more than approximately 50% the increase in developed force levelled off.

CONCLUSIONS

All the class III agents investigated showed a positive inotropic effect, which may be of advantage when compared to conventional class I antiarrhythmic agents, which have cardiodepressant actions. Compared to UK-68,798 and E-4031, H 234/09 showed a less unfavourable profile in terms of dispersion of repolarisation, which theoretically may reduce the risk of arrhythmias associated with delayed repolarisation. However, this less unfavourable profile must, like the positive inotropic effect, ultimately be investigated in clinical trials.

V-region directed selection in differentiating B lymphocytes

We here analyse the repertoire of VH7183 rearrangements isolated from different stages of B cell differentiation in adult mice. The nucleotide sequence analyses of VH7183-D-JH rearrangements derived from large pre-B cells (B220+, mu-), small pre-B cells (B220+, mu-) and mature B cells (B220+, mu+) isolated from adult bone marrow revealed a sequential accumulation, among functional rearrangements, of D segments of the FL16 family and a depletion of D segments using the second and the third reading frame (RF). One member (VH7183.1) of the VH7183 gene family was utilized in 60-80% of the rearrangements of all populations analysed. In neonates the majority of the rearrangements utilizing this gene was found to be functional. In contrast, > 96% of the VH7183 rearrangements isolated from adult spleen were non-functional. These data provide evidence for cellular selection of VH regions acting at different points of the B cell differentiation pathway and at the transition of B cells from the bone marrow to the periphery.

Growth hormone-binding protein determination in plasma: a comparison of immunofunctional and growth hormone-binding assays

The recent development of an immunofunctional assay for GH-binding protein (GHBP) facilitates measurement of GHBP in biological fluids. Previous methods employed GH binding followed by size exclusion chromatography to determine GHBP levels (GH binding assay), and a considerable body of information exists based on data obtained with that type of assay. To cross-validate the two methods and permit comparison of results obtained in the two assays, we measured GHBP by both methods in 61 plasma samples from normal adults (aged 19-69), 10 patients with acromegaly, 2 patients with Laron dwarfism, and in a normal adult plasma pool. The results show a good overall correlation between the two methods (r = 0.669). However, for individual observations, the coefficient of determination was not high enough to permit interconversion of data with high precision. There is both biological and methodological variation in GHBP levels, rendering the interpretation of a single observation difficult except in the extreme range. The range of values was wider in the immunoassay (56-1187 pmol/L) than in the GH-binding assay (12.1-36.1% GH bound/400 microL). There was no significant sex difference in plasma GHBP levels, nor was there an age-dependent trend in adult subjects as assessed by both assays. Patients with acromegaly had significantly decreased GHBP levels in both assays, but the majority of the values were within the low normal range. The two patients with Laron dwarfism had undetectable GHBP in both assays. The previously defined unit of GHBP (i.e. the amount contained in 1 ml pooled adult plasma) corresponds to 256 fmol GHBP as determined by immunofunctional assay.

Quantitative sequence-activity models (QSAM)--tools for sequence design

Models have been developed that allow the biological activity of a DNA segment to be altered in a desired direction. Partial least squares projections to latent structures (PLS) was used to establish a quantitative model between a numerical description of 68 bp fragments of 25 E.coli promoters and their corresponding quantitative measure of in vivo strength. This quantitative sequence-activity model (QSAM) was used to generate two 68 bp fragments predicted to be more potent promoters than any of those on which the model originally was based. The optimized structures were experimentally verified to be strong promoters in vivo.

Radioimmunolocalization of hepatic metastases and subcutaneous xenografts from a human colonic cancer in the nude rat. Aspects of tumour implantation site and mode of antibody administration

Antibody localization was analyzed following intraperitoneal (i.p.) or intravenous (i.v.) injection of the 125I-labelled anti-CEA-MAb I-38S1 in 44 nude rats, in order to evaluate the influence of tumour implantation site and the route of MAb administration. The animals were xenografted with a human colonic cancer (LS 174 T), either in the form of hepatic metastases, subcutaneous (s.c.) tumours or both. Tissue measurements, 4 days after MAb injection, showed better uptake for hepatic than for s.c. tumours, irrespective of the route of antibody administration. Antibody accumulation per g liver metastases was not size dependent for noduli weighing between 4 and 1,110 mg. MAb excretion evaluated in 20 animals and blood activity studied in 11 rats were equivalent 24-96 h following i.p. and i.v. injection. Dissimilar autoradiographic patterns were seen in hepatic metastases with predominantly peripherally located clusters following i.p. and more homogeneously distributed grains after i.v. MAb administration. The results indicate that tumour implantation site has a quantitative, and the route of administration at least a qualitative impact on the tumour accretion of anti-CEA MAb I-38S1 in the present xenograft model.

Core temperature measured in the auricular canal: comparison between four different tympanic thermometers

Four different tympanic thermometers, absorbing infra-red radiation, (FirstTemp, Diatek, Ivac and Genius) were studied. Variations from repeated measurements and reliability of tympanic temperature compared to oesophageal, rectal and pulmonary artery temperature were studied. Core temperature measured by the "FirstTemp" and the "Genius" thermometers showed slightly higher values than core temperature measured by oesophageal, rectal and pulmonary artery thermistors. Compared to oesophageal temperature "FirstTemp" showed 0.56 degrees C and "Genius" 0.28 degrees C higher values, while the "Diatek" and the "Ivac" gave slightly lower values (-0.5 degrees C and -0.28 degrees C). All four thermometers were found accurate for repeated measurement both in terms of standard deviation and coefficient of variance. All four tympanic thermometers showed good accuracy for changes in core temperatures compared to the reference thermistors (r2 values 0.96 for "FirstTemp", 0.88 for "Diatek", 0.96 for "IVAC" and 0.95 for "Genius"). The tympanic thermometer was found to be a valuable alternative for measuring core temperature in most clinical settings.

The heparin-binding domain of extracellular superoxide dismutase C and formation of variants with reduced heparin affinity

A fundamental property of the secretory tetrameric extracellular superoxide dismutase (EC-SOD) is its affinity for heparin and analogues, in vivo, mediating attachment to heparan sulfate proteoglycans located on cell surfaces and in the connective tissue matrix. EC-SOD is in vivo heterogeneous with regard to heparin affinity and can be divided into subclasses; A which lacks heparin affinity, B with intermediate affinity, and C with strong heparin affinity. The EC-SOD C subunits contain 222 amino acids and among the last 20 carboxyl-terminal amino acids, 10 are positively charged and six of these are located in a cluster in positions 210-215. To analyze if this local accumulation of basic amino acids is responsible for heparin binding we produced three series of recombinant EC-SOD (rEC-SOD) variants, six containing amino acid exchanges in the carboxyl-terminal end, four with truncations, and two with both truncations and substitutions. Exchange of positively or negatively charged amino acids on the carboxyl-terminal side of the cluster results in only minor modifications in heparin affinity, whereas substitution of three of the amino acids in the cluster abrogates the heparin binding. Insertions of stop codons at different positions resulted in either C or A but not B class EC-SOD. In an attempt to produce EC-SODs with intermediate heparin affinities, plasmids defining C and A class EC-SOD were cotransfected into Chinese hamster ovary cells. In addition to the parental A and C class EC-SOD forms, two variants with intermediate heparin affinities were formed. Coincubation of EC-SOD C and A resulted in the appearance of one heterotetramer with intermediate affinity for heparin. We conclude that the cluster of six basic amino acids forms the essential part of the heparin-binding domain and that the composition of the four subunits in the EC-SOD tetramer determines the affinity for heparin. This domain is different from heparin-binding domains of other proteins, and its localization allows the distribution of EC-SOD in vivo to be regulated by proteolytic processing.

Electrophysiologic and hemodynamic effects of H 234/09 (almokalant), quinidine, and (+)-sotalol in the anesthetized dog

The electrophysiologic and hemodynamic effects of H 234/09 (Almokalant), a novel class II antiarrhythmic agent, were studied in the anesthetized dog. H 234/09 (1.0 mumol/kg i.v.) significantly prolonged the atrial and ventricular effective refractory periods, the ventricular monophasic action potential duration, and the paced QT interval. At this dose, atrial, ventricular, and atrioventricular conduction was not affected, aortic blood pressure was not changed, and contractile force was transiently increased. The effects on cardiac repolarization and refractoriness induced by H 234/09 were both larger and more long lasting than the effects observed after quinidine (11.8 mumol/kg) and (+)-sotalol (9.7 mumol/kg). However, both quinidine and (+)-sotalol significantly reduced the aortic blood pressure and (+)-sotalol also decreased cardiac contractility. The effect of H 234/09 on atrial refractoriness was very little influenced by the paced heart rate and was twice as large as the corresponding effect in the ventricle. In conclusion, H 234/09 has electrophysiological properties suggestive of a class III antiarrhythmic. H 234/09 may have a favorable therapeutic profile compared to both quinidine and (+)-sotalol, especially for the treatment of atrial arrhythmias.

A decision support system for predicting a recurrence of breast cancer; a prospective study of serum tumour markers TAG 12, CA 15-3 and MCA

The aim of the present study was to evaluate the clinical value of the preoperative serum tumour markers TAG 12, CA 15-3 and MCA in predicting a recurrence of breast cancer patients. The sensitivity of the TAG 12 test was 54%, that of the CA 15-3 test 15% and that of the MCA test 15% in predicting a recurrence of breast cancer. The most important predictor of breast cancer recurrence was TAG 12. In order to evaluate the contributions of different tumour marker serum test, a stepwise discriminant analysis was carried out. The discriminant function (DF) is DF = TAG 12 x 0.061 - CA 15-3 x 0.1336 - 0.396. The sensitivity of the DF in detecting recurrence of breast cancer was 63% with a specificity of 90% and an efficiency of 75%. In conclusion, the results indicate that a new tumour marker TAG 12 is superior to CA 15-3 and MCA in predicting breast cancer recurrence. In this study the discriminant function including TAG 12 and CA 15-3 was superior to single preoperative tumour marker tests. The results speak for the use of a decision support system to aid in predicting a recurrence of breast cancer.

Selection against N-region diversity in immunoglobulin heavy chain variable regions during the development of pre-immune B cell repertoires

The generation of Ig heavy chain chain diversity is dependent on the ordered rearrangement of three different, i.e. variable (VH), diversity (DH), and joining (JH), germline gene segments, exonuclease nibbling of the terminals of these gene segments, and the addition of template-independent nucleotide (N-sequences) in the junctions of these segments. The latter process has recently been reported to be limited within B cells formed during early ontogeny. In this study, we have analysed a large number of VHDJH rearrangements isolated from genomic DNA of adult and neonatal C57BI/6 mice using the polymerase chain reaction (PCR) technique. A comparison of functional versus non-functional VHDJH rearrangements derived from these PCR libraries, or from a set of previously published clones of BALB/c origin, revealed a selection against N-region diversity both in neonatal and adult B cell repertoires. This selection process is most pronounced in the early development of the immune system but can still be observed in the adult. Furthermore, selection against N-sequence additions was evident amongst neonatal VHDJH rearrangements utilizing both VH 7183 and VH J558 genes, but only in VH 7183 utilizing clones of adult origin. These results imply that in addition to a developmentally controlled onset of N-sequence additions, cellular selection against N-region diversity exist both in the neonatal and adult immune system.

Antiarrhythmic effects of potassium channel openers in rhythm abnormalities related to delayed repolarization

BACKGROUND

Earlier observations have indicated that repolarization-delaying agents may, under certain circumstances, have the propensity to induce polymorphous ventricular tachyarrhythmias (PVTs) (i.e., torsade de pointes). We have studied whether the potassium channel opener pinacidil and two of its pyridylcyanoguanidine analogues (P1075 and P1188) have any antiarrhythmic effects on clofilium-induced PVTs and triggered responses in rabbits in vivo and in vitro.

METHODS AND RESULTS

Anesthetized rabbits were pretreated with propranolol (2 mumol/kg i.v.) and subsequently given a concomitant intravenous infusion of clofilium (63 nmol/kg/min for maximally 15 minutes) and the alpha 1-agonist methoxamine (70 nmol/kg/min). In vehicle-pretreated rabbits (n = 19), clofilium invariably induced PVTs, which closely resembled torsade de pointes and were preceded by a marked prolongation of the QTU interval (27 +/- 2.4%, p less than 0.001). In a separate group of seven rabbits in which monophasic action potentials were recorded from the left ventricular endocardium, the tachyarrhythmia was preceded by deflections consistent with early afterdepolarizations (EADs) of the plateau repolarization phase of the monophasic action potentials. Intravenous administration of the pyridylcyanoguanidines in doses reducing mean arterial blood pressure by 25 or 50 mm Hg, respectively, was associated with a dose-dependent attenuation in the occurrence of clofilium-induced PVTs. In the pinacidil-pretreated rabbits (0.41 mumol/kg or 1.86 mumol/kg i.v.), the occurrence of PVTs was reduced from seven of seven rabbits to five of six and to three of seven rabbits (p = 0.035 versus vehicle-pretreated controls), respectively. In rabbits pretreated with the low dose of P1075 (0.01 mumol/kg i.v.), PVT occurrence was reduced from six of six rabbits to two of six rabbits (p = 0.030), whereas in six rabbits given the high dose of P1075 (0.13 mumol/kg), no PVTs appeared (p = 0.001). When the sulfonylurea glibenclamide (10 mumol/kg i.v.) was administered to rabbits before P1075 (0.13 mumol/kg) was infused, clofilium induced PVTs in five of six rabbits (not significantly different from the incidence in the vehicle-pretreated rabbits). Pretreatment with P1188 (4.36 mumol/kg or 11.88 mumol/kg i.v.) caused a reduction in the occurrence of PVT from six of six rabbits to five of six and to none of six rabbits (p = 0.001), respectively. In the six animals pretreated with the high dose of P1188 in which no clofilium-induced arrhythmias were elicited, glibenclamide (20 mumol/kg i.v.) was injected after the entire dose of clofilium had been administered. In these rabbits, premature ventricular systoles and PVTs appeared within a few minutes in five and four of the animals, respectively. In contrast to the pyridylcyanoguanidines, diltiazem pretreatment (0.9 mumol/kg i.v., decreasing arterial pressure by 50 mm Hg) did not attenuate PVT occurrence (five of six rabbits). Acute administration of P1075 (0.13 mumol/kg) during recurrent attacks of PVTs abruptly regularized the rhythm in 12 of 13 animals and diminished EADs observed in monophasic action potentials recorded from the left ventricular endocardium. In in vitro experiments, action potentials were simultaneously recorded from rabbit Purkinje fibers and ventricular muscle cells. Clofilium markedly prolonged action potential duration in Purkinje fibers but not in ventricular muscle cells, and eventually, bradycardia-dependent EADs and triggered activity were elicited. P1075 completely abolished EADs and triggered activity in all (six of six) experiments. Glibenclamide antagonized the suppressive effect of P1075; hence, EADs and triggered responses reappeared and resembled those present before P1075.

CONCLUSIONS

These results suggest that ATP-sensitive potassium channel activat

BACKGROUND

Earlier observations have indicated that repolarization-delaying agents may, under certain circumstances, have the propensity to induce polymorp

Expression of serum insulin-like growth factors, insulin-like growth factor-binding proteins, and the growth hormone-binding protein in heterozygote relatives of Ecuadorian growth hormone receptor deficient patients

Recently, an isolated population of apparent GH-receptor deficient (GHRD) patients has been identified in the Loja province of southern Ecuador. These individuals presented many of the physical and biochemical phenotypes characteristic of Laron-Syndrome and are believed to have a defect in the GH-receptor gene. In this study, we have compared the biochemical phenotypes between the affected individuals and their parents, considered to be obligate heterozygotes for the disorder. Serum GH, insulin-like growth factor I and II (IGF-I and IGF-II) levels were measured by RIA Insulin-like growth factor binding proteins. (IGFBPs) were measured by Western ligand blotting (WLB) of serum samples, following separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and relative quantitation of serum IGFBPs was performed with a scanning laser densitometer. Serum GH-binding protein (GHBP) levels were measured with a ligand-mediated immunofunctional assay using a monoclonal antibody raised against the GHBP. These values were then compared to values obtained from normal, sex-matched adult Ecuadorian controls, to determine if the above parameters were abnormal in the heterozygotes. The serum IGF-I levels of the GHRD patients were less than 13% of control values for adults and 2% for children. However, the IGF-I levels of both the mothers and fathers were not significantly different from that of the control population. The serum IGF-II levels of the GHRD patients were approximately 20% of control values for adults and 12% for the children. The IGF-II levels of the mothers were reduced, but were not significantly different from that of the control population. However, IGF-II levels of the fathers were significantly lower than those of controls (64% of control male levels). WLB analysis of serum IGFBP levels of the affected subjects demonstrated increased IGFBP-2 and decreased IGFBP-3, suggesting an inverse relationship between these IGFBPs. The GHRD patients who had the lowest serum IGFBP-3 levels (as measured by WLB) demonstrated a serum protease activity that could proteolyze 125I-IGFBP-3. GHRD patients who had higher serum IGFBP-3 levels lacked this serum protease activity. There were no differences in the serum IGFBP profiles of the mothers or the fathers for either IGFBP-2 or IGFBP-3, and serum from both groups lacked the ability to significantly proteolyze 125I-IGFBP-3. While GHRD patients had very low levels of serum GHBP, some patients did have measurable GHBP levels.(ABSTRACT TRUNCATED AT 400 WORDS)