Developmentally controlled selection of antibody genes: characterization of individual VH7183 genes and evidence for stage-specific somatic diversification

Nucleotide sequence analysis of a large number of rearranged immunoglobulin heavy chain V region genes allowed the identification of six new members of the VH7183 gene family. These six new genes plus the eight previously defined genes agrees with the previously estimated complexity of this gene family. Twelve of these genes were represented among the isolated clones. A comparison of the clones, derived from 1-day- and 14-week-old BALB/c mice, suggested a biased and developmentally controlled VH7183 gene utilization. Furthermore, a developmentally controlled, non-random distribution of the functional vs. non-functional VHDJH rearrangements was observed among clones utilizing genes of this family, suggesting unsuspected regulatory aspects of Ig rearrangements in the process of B cell differentiation. Finally, a limited junctional diversity was revealed among the neonatal clones as the result of a low frequency of N-sequence addition. A similar discrepancy was also observed between neonatal and adult VHJ558 clones. In conclusion, these data suggest a programmed generation of B cell diversity similar to what has been observed for the establishment of gamma/delta T cell repertoires.

Comparison of tumour markers TAG 12 with CA 15-3 and MCA in breast cancer diagnosis

The aim of the present study was to evaluate the clinical value of the new tumour marker TAG 12 in sera from patients with breast cancer (n = 123), patients with benign breast disease (n = 30) and normal controls (n = 38). The results for TAG 12 were compared with those for CA 15-3 and MCA. The cut-off levels (90% specificity) determined for each test in the benign and control groups were 57.5 kU/1 for TAG 12, 24.8 kU/1 for CA 15-3 and 11.8 kU/1 for MCA. The diagnostic sensitivity of the TAG 12 test was 0.30, 0.19 for CA 15-3 test and 0.20 for MCA test in detecting breast cancer. TAG 12, CA 15-3 and MCA tests were tested in a multivariate analysis to find the best combination of independent predictors of breast cancer. The most important predictor of breast cancer was TAG 12. In order to evaluate the contributions of different tumour marker serum tests a stepwise discriminant analysis was carried out. The discriminant function is DF = TAG 12 x 0.0349 + CA 15-3 x 0.0568 + MCA x (-0.33) - 0.53. The sensitivity of the DF in detecting breast cancer was 31% with a specificity of 91% and a efficiency of 52%. The correlation coefficient in breast cancer patients between TAG 12 and CA15-3 measurements was 0.95, and 0.90 between TAG 12 and MCA measurements. In conclusion, the results indicate that TAG 12, CA 15-3 and MCA have only limited value in the diagnosis of breast cancer, but their role in monitoring and follow up of breast cancer patients is a subject for further investigation.

Prolonged action potential duration and positive inotropy induced by the novel class III antiarrhythmic agent H 234/09 (Almokalant) in isolated human ventricular muscle

The electromechanical properties of H 234/09 (Almokalant), a novel class III antiarrhythmic agent, was examined in isolated human ventricular muscle strips excised from patients undergoing mitral valve replacement. Using transmembrane microelectrode recording techniques, we demonstrated that H 234/09 markedly prolonged the action potential duration (APD) without affecting the maximal rate of depolarization or action potential amplitude. At 75 and 90% repolarization APD was prolonged to a similar extent, whereas the lengthening at 50% repolarization was somewhat less marked. In isometrically contracting muscle strips, H 234/09 increased peak developed force and its maximal rate of rise (dF/dt) and fall (-dF/dt) in a concentration-dependent manner, whereas time to peak developed force was unaltered. We conclude from these studies that H 234/09 is a class III agent in human ventricular muscle and that the class III effect is linked with a positive inotropic response.

On the role of the peptide galanin in regulation of growth hormone secretion

The effects of the peptide galanin on growth hormone secretion were studied in vitro using cultured rat and human anterior pituitary cells, and in vivo by iv administration of galanin in both rats and humans. Galanin in concentrations from 10 nmol/l to 1 mumol/l did not alter basal GH release, but slightly inhibited GHRH-stimulated GH release from cultured rat anterior pituitary cells. Galanin (1 mumol/l) did not significantly change basal or GHRH-stimulated GH secretion from cultured human anterior pituitary cells. In contrast, iv injection of 1 microgram (300 pmol) galanin to rats induced an increase in plasma GH that was reproducible at repetitive injections. The galanin-induced GH release in rats was of a lower magnitude than the increase in plasma GH after iv injections of GHRH, and was seen with a 5-15 min delay in comparison to iv administered GHRH. In man, iv infusions of galanin (40 pmol.kg-1.min-1.(40 min)) also caused a significant increase in plasma GH, but it occurred 25-30 min after the beginning of the infusion. These results suggest an indirect action of galanin on GH release in both rats and humans, i.e. galanin does not directly affect the somatotropes. In agreement with a central action, no binding sites for galanin could be demonstrated in the rat anterior pituitary by autoradiography. Since galanin did not affect somatostatin release from fragments of rat mediobasal hypothalamus, the stimulatory effects of galanin on GH release are most likely mediated via a stimulatory effect on GHRH neurons.

Germ-line origin of functional idiotypic interactions: identification of two idiotypically connected, natural antibodies that are encoded by germ-line gene elements

Two monoclonal, natural IgM antibodies derived from normal BALB/c mice were selected on the basis of being idiotypically complementary and functionally connected. Nucleotide sequence analysis of their respective heavy and light chain V regions showed that both of the clones expressed VH, D, JH, VL and JL gene segments of germ-line origin. Furthermore, none of the clones displayed N-sequence additions. These data suggest a germ-line origin of a functional idiotypic network and confirm a minimized contribution of somatic diversification through template-independent addition of N-nucleotides in neonatal B cell repertoires.

Cardioprotective effects of recombinant human extracellular-superoxide dismutase type C in rat isolated heart subjected to ischemia and reperfusion

The cardioprotective effect of recombinant human extracellular-superoxide dismutase type C (rh-EC-SOD C) was studied in isolated perfused rat heart subjected to left coronary artery ligation for 30 or 60 min followed by 30-min reperfusion. A comparison was made with the effects of bovine CuZn-SOD. Reperfusion after 30-min coronary artery ligation was associated with a release of creatine kinase (CK) into the coronary effluent (71 +/- 5.2 IU/30 min), which was markedly reduced (39 +/- 5.5 IU/30 min) in hearts perfused with rh-EC-SOD C (28 mg/L). CuZn-SOD (4 or 20 mg/l) or a lower concentration of rh-EC-SOD C (5.6 mg/l) did not significantly attenuate CK outflow during reperfusion, however. In both vehicle- and SOD-treated hearts, the left ventricular developed pressure (LVDP) and the coronary flow recovered to 80-90% of baseline at the end of the reperfusion period. Increasing the ischemic period from 30 to 60 min caused a much more pronounced cardiac injury measured after 30-min reperfusion. In the hearts that received vehicle, recovery of LVDP (in percentage of baseline values) at the end of reperfusion was 58 +/- 2%, which was increased to 84 +/- 3 and 83 +/- 5% after treatment with rh-EC-SOD C (28 mg/L) and CuZn-SOD (20 mg/L), respectively. The corresponding values for recovery in coronary flow were 54 +/- 3% (vehicle), 69 +/- 4% (rh-EC-SOD C), and 74 +/- 3% (CuZn-SOD).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical evaluation of a new tumour marker TAG 12 in breast cancer

The aim of the present study was to evaluate the clinical value of the new tumour marker TAG 12 in sera from patients with breast cancer, patients with benign breast disease and normal controls. The results for TAG 12 were compared with those for CA 15-3 and MCA. The cut-off levels (95th percentile) determined for each test in the benign and control groups were 59 KU/l for TAG 12, 27 KU/l for CA 15-3 and 12 KU/l for MCA. The diagnostic sensitivity of the TAG 12 test was 0.30 (cut-off level 59 KU/l), 0.25 for CA 15-3 test (cut-off level 27 KU/l) and 0.15 for MCA test (cut-off level 12 KU/l) in detecting breast cancer. The combination of TAG 12, CA 15-3 and MCA reached the diagnostic sensitivity 0.35, specificity 0.90, efficiency 0.68, LR+ 3.5, and LR- 0.72 The correlation coefficient in breast cancer patients between TAG 12 and CA 15-3 was 0.99 and the correlation coefficient between TAG 12 and MCA was 0.95. In conclusion, the results indicate that TAG 12, CA 15-3 and MCA have only limited value in the diagnosis of breast cancer, but their role in monitoring and follow-up of breast cancer patients is a subject for further investigation.

QTU-prolongation and torsades de pointes induced by putative class III antiarrhythmic agents in the rabbit: etiology and interventions

When low doses of clofilium were administered to conscious rabbits, ventricular tachyarrhythmia (VT) with features typical of torsades de pointes developed. This arrhythmia was further studied and characterized in chloralose-anesthetized rabbits. In 20 of 20 rabbits, VT developed after a mean cumulative dose of 0.53 +/- 0.04 mumol/kg clofilium, provided an infusion of the alpha 1-agonist methoxamine (15 micrograms/kg/min) was given concomitantly. The arrhythmia was preceded by a marked prolongation of the QTU interval and the monophasic action potential duration, as well as signs of early afterdepolarizations (EADs). In seven of 10 rabbits receiving only clofilium (cumulative dose, 20.8 mumol/kg), no VT occurred (p less than 0.001 compared to the incidence in animals given both methoxamine and clofilium). In animals given both methoxamine and clofilium, pretreatment with prazosin (1 mg/kg i.v., n = 4) attenuated the arrhythmia, whereas diltiazem (0.5 mg/kg i.v., n = 4) or propranolol (0.5 mg/kg i.v., n = 8) was ineffective. Acute intervention with prazosin, isoproterenol, pinacidil, or magnesium sulfate promptly regularized the rhythm in animals with VT. Prazosin and pinacidil were equally effective in beta-blocked rabbits. When other agents known to retard the repolarization currents (sematilide, UK-68,798, LY97119, amperozide, and cesium chloride) were examined, a strong correlation (r = 0.99, p less than 0.001) between the potency of the drug to prolong the QTU interval and the proarrhythmic potential was obtained. This experimental model may represent an appropriate alternative for studying the acquired ("pause-dependent') long QT syndrome.

Effects of growth hormone and hypophysectomy of pregnant rats on serum concentrations of pregnancy-associated murine protein-1

Continuous infusion of bovine GH to hypophysectomized non-pregnant rats increased serum concentrations of pregnancy-associated murine protein-1 (PAMP-1) to the levels of adult female rats and pregnant rats. Serum concentrations of PAMP-1 were followed from Day 16 of gestation until 3 days after parturition in hypophysectomized (on Day 14 of gestation) and intact pregnant rats. In the intact pregnant rat there was a decrease in PAMP-1 values from Day 16 until delivery. The serum concentrations of PAMP-1 in hypophysectomized pregnant rats were similar to those in intact pregnant rats before parturition, but PAMP-1 concentrations decreased markedly after parturition in the hypophysectomized rats. We suggest that the serum concentrations of PAMP-1 can be maintained without pituitary GH in late pregnancy, while serum values of PAMP-1 in non-pregnant rats is dependent upon a continuous secretion of pituitary GH.

Analysis of free inositol trisphosphate in heart tissue by FPLC and isotachophoresis

Recent, increasing interest in inositol tris(1,4,5)phosphate (IP3) turnover and metabolism has led to a need for a fast and quantitative determination of this compound in various tissues. These requirements are fulfilled by separation in different steps (FPLC and Sephadex G-10) culminating in further separation and quantification by isotachophoresis. Isotachophoresis means a migration of ion species of the same sign in an electrical field with all ions moving with the same velocity. The migration takes place when an electrical field is applied to a system of electrolytes of specific design. Detection was carried out by monitoring conductivity changes. The method is highly sensitive and allows measurements of IP3 in the pmolar range. Linearity was demonstrated over a wide range, 50-4500 pmol. The total imprecision was low with a coefficient of variation of 3%. When determining in biological tissue the recovery was estimated to be close to 100%. The mean content of IP3 in 15 rat heart specimens was 44.3 pmol/mg dry weight corresponding to tissue samples in the order of 4 mg wet weight. By noradrenaline stimulation myocardial content of IP3 increased by 50%.

The plasma pattern of growth hormone in conscious rats during late pregnancy

The plasma GH levels of female rats during late pregnancy were determined using an automatic method for repetitive blood sampling from conscious animals. The plasma GH patterns were analysed by a pulse analysis computer program (PULSAR). The mean plasma GH levels were about twofold higher in pregnant females on days 15, 18 and 22 of gestation than in age-matched non-pregnant females. The basal plasma GH levels were also increased, while there was no change in GH pulse amplitude or frequency. The augmentation of GH release was even more pronounced on day 20 of gestation, with a fourfold increase in mean plasma GH levels compared with those in non-pregnant females. This increase reflected an increase in both basal plasma GH levels and GH pulse amplitude, but there was no increase in pulse frequency. In female rats that delivered on day 22 of gestation, the basal and mean plasma GH levels increased during parturition. Pregnant females consistently responded to multiple i.v. infusions of 1 microgram human GH-releasing factor analogue (hGRF(1-29)-NH2) given at 45-min intervals on day 18 of gestation. Both basal and GRF analogue-stimulated plasma GH levels were undetectable after hypophysectomy of pregnant rats. The present study demonstrates an increase in basal plasma GH levels during late pregnancy and a marked increase in both basal plasma GH levels and GH pulse amplitude on day 20 of gestation. Furthermore, hypophysectomy of pregnant rats results in undetectable GH levels, indicating that the high levels of GH during pregnancy are derived from the pituitary.

Genetic basis of the neonatal antibody repertoire: germline V-gene expression and limited N-region diversity

We report here on the molecular characterization of heavy and light chain V-regions of antibodies isolated from the highly connected idiotypic network of the newborn BALB/c mouse. Nucleotide sequence analysis of eight hybridomas confirmed their germline origin. Furthermore, in contrast to most hybridomas and myelomas derived from adult mice, the majority of these clones were found to lack N-region sequences. These data show that somatic processes amplifying junctional diversity are relatively inactive early in ontogeny, and that germline gene expression alone ensures idiotypic complementarities in the developing immune system.

Endogenous growth hormone (GH) secretion in male rats is synchronized to pulsatile GH infusions given at 3-hour intervals

The feedback effects of GH on its own secretion were studied in conscious male rats receiving intermittent iv infusions of human GH. Male Sprague-Dawley rats (150-180 g) were implanted with double bore iv cannula. Infusions of human GH (hGH) or buffer were given for up to 32 h, while frequent microsamples (20 microliters) of blood were withdrawn simultaneously using an automatic blood-sampling system. The endogenous GH pulses became synchronized to pulsatile hGH infusions (2.1 U/kg.infusion) given at 3-h intervals. After two or more hGH infusions episodic GH release was present in most rats, and all endogenous pulses occurred concomitantly with the hGH infusions. After 24 h of hGH treatment the endogenous pulses were still synchronized to the every 3 h hGH infusions. In addition, the pulse amplitude was lower than that in vehicle-treated animals (74 +/- 12 vs. 215 +/- 35 ng/ml; P less than 0.01). At this time a complete (1.5-h) phase shift of the 3-hourly hGH infusions markedly suppressed endogenous GH pulses in all rats. In another experiment where the same daily dose of hGH was given in iv infusions every 1.5 h instead of every 3 h, the endogenous GH pulses were irregular, infrequent, and suppressed. Infusions at 3-h intervals of a lower dose of hGH (0.42 U/kg.infusion) did not affect the timing or amplitude of endogenous GH pulses compared to those in buffer-infused animals. The endogenous GH pulses were not synchronized between animals given 0.42 U/kg hGH or buffer at 3-h intervals. It is concluded that the endogenous GH pulses in male rats became synchronized to intermittent infusions of hGH at 3-h (but not 1.5-h) intervals. The fact that there were no endogenous pulses between the 3-hourly infusions suggests that the feedback effect of a GH pulse lasts for approximately 3 h. This mechanism may be involved in the control of the GH secretory pattern in male rats.

Breast milk zinc and copper concentrations in Bangladesh

Breast-fed infants in Bangladeshi villages were weighed at 1, 2, 6, 9 and 12 months. The concentrations of zinc and copper in the breast milk were measured and the daily intake of these elements calculated. Breast milk Zn concentration decreased over the year but was comparable with that found in developed countries. The calculated daily intake decreased from 17.7 to 8.0 mumol (10-30% of recommended dietary allowances (RDA); National Academy of Sciences, 1980). Breast milk Cu concentration also fell over the year and was lower than that reported from developed countries. Calculated daily Cu intake was 1.95-2.63 mumol (RDA 7.81-15.63 mumol). Deficiencies of trace elements may therefore be a problem in poorly nourished communities where breast feeding is continued for several years with only small amounts of additional food. Breast milk may not be adequate as the only source of infant nutrition after the first few months of life in Bangladesh.

Morphometrical studies of human femoral condyles

Thirty-six cadaver knees were examined by various morphometrical methods in order to obtain mathematical and graphical data concerning the geometry of the lower end of the femora. It was found that the paramedian sagittal curves represented magnifications of a certain curvature pattern specific to the medial and the lateral femoral condyle. These curves could be expressed mathematically for each condyle. Furthermore, we found dimensional as well as geometrical intervariations between the different size groups in the knee sample. This could serve as an argument for preferring a different design for medial and lateral condyle components in knee prostheses.

Plasma growth hormone pattern regulates epidermal growth factor (EGF) receptor messenger ribonucleic acid levels and EGF binding in the rat liver

It has recently been shown that GH increases the number of available hepatic receptors for epidermal growth factor (EGF). In the present study the effects of the sexually dimorphic plasma GH pattern (higher pulsatility in male rats) on hepatic EGF binding and EGF receptor mRNA concentration were investigated. The specific binding of [125I]EGF to purified liver membranes was about 2-fold higher in male rats than in females on days 35, 50, and 80 of life. EGF receptor mRNA levels, as determined by an RNase protection solution hybridization assay, were higher in males only on days 47-50. Hypophysectomy on day 50 reduced the EGF receptor mRNA concentration to a level that did not differ between male and female rats. In hypophysectomized rats of both sexes, intermittent GH treatment (sc injections every 12 h for 7 days) enhanced hepatic EGF receptor mRNA concentrations to normal male levels, while continuous GH administration was less effective. Northern blot analysis indicated that transcripts with apparent sizes of 9.5 and 6.6 kilobases were dependent on the plasma GH pattern. Intermittent iv GH replacement therapy for 5 days given at 3-h intervals by an automatic iv infusion system increased the hepatic EGF receptor mRNA concentration as well as specific EGF binding, whereas continuous iv GH infusion was ineffective. These results show that a pulsatile plasma GH pattern, similar to that of male rodents, is markedly more effective in enhancing hepatic EGF receptor mRNA levels and EGF binding than a continuous feminine GH pattern. These results are consistent with a pretranslatory stimulation of EGF receptor synthesis by pulsatile GH.

Establishment and functional implications of B-cell connectivity

We have discussed some aspects of the structure of the normal immune system, particularly the B-cell compartment. We have argued: that a basic property of the natural antibody repertoire is constituted by high degrees of connectivity within the immune system as well as between the system and other components of the organism; that the complementarities constituting this connectivity are based on self-self interactions, high degrees of degeneracy or somatically selected interactions and that these properties are conserved through evolution, to ensure self-reference; that by evolutionary selection, antibody V-genes encoding such structural properties are ensured to be expressed early in ontogeny. The set of highly connected cells will be kept through ontogeny and form the basis for a compartment of naturally-activated lymphocytes making up 10-15% of the total lymphocyte population. As suggested before, this pool of connected cells may be responsible for maintenance of normal network dynamics and prevention of autoaggression.

Ramiprilat attenuates the local release of noradrenaline in the ischemic myocardium

The effects of the converting enzyme inhibitors ramiprilat and enalaprilat on ischemia-induced release of noradrenaline (NA) were examined in the isolated perfused rat heart, submitted to 30 min of total flow restriction followed by 5 min of reperfusion. Ramiprilat (2.6 nM-2.6 microM) caused a concentration-dependent decrease in the efflux of NA at reperfusion. The maximal effect (about 70% reduction) was observed at a concentration of 26 nM. In contrast, enalaprilat (10 nM-10 microM) caused no reduction in NA efflux until at a high concentration (10 microM, NA efflux reduced by about 20%). Moreover, the prodrugs ramipril and enalapril (added to the perfusion medium) were without any significant effects on ischemia-induced NA release. Both the angiotensin II receptor antagonist saralasin (0.1 microM) and bradykinin (0.1 and 1 nM) caused marked reductions in ischemic NA efflux. However, when indomethacin (10 microM) was added to the perfusion medium, the effects of bradykinin (1 nM) and ramiprilat (26 nM) on NA efflux were abolished. Likewise, in the presence of angiotensin II (0.1 microM) the effect of ramiprilat was no longer evident. The magnitude of cellular injury, expressed as efflux of creatine kinase during reperfusion, was reduced by bradykinin (0.1 and 1 nM) and by ramiprilat (by about 55% at 2.6 microM). It is concluded that ramiprilat, at therapeutically relevant concentrations, attenuates the ischemia-induced mobilization of NA via a reduction in local angiotensin II production and/or bradykinin degradation. The lack of effect of enalaprilat in this model may reflect differences between converting enzyme inhibitors regarding tissue accumulation or the potency of local enzyme inhibition.

Estrus cycle-dependent co-variation of insulin-like growth factor-I (IGF-I) messenger ribonucleic acid and protein in the rat ovary

It has been suggested that insulin-like growth factor-I (IGF-I) exerts paracrine or autocrine actions in the ovary and may play a role in the regulation of ovarian function. We have examined ovarian levels of IGF-I mRNA and IGF-I protein throughout the estrus cycle. The lowest levels of IGF-I mRNA were found on proestrus (12.00 h). The mRNA levels on estrus (12.00 h) were significantly (P less than 0.05) higher than on proestrus. The correlation between the levels of IGF-I and IGF-I mRNA was linear and significant (r = 0.706; P less than 0.01). Our observations that the IGF-I gene expression and translation vary during the estrus cycle, with an increase between proestrus and estrus, suggest that the gonadotropin surge could be of importance for the regulation of IGF-I in vivo and that IGF-I may be involved in the cell proliferation and differentiation caused by these hormones.

Osseointegrated knee prostheses. An experimental study in rabbits

Osseointegration, defined as direct bone-to-implant contact, has been suggested as an approach for improving the results of arthroplasties of the major joints. An experimental investigation in femoral-patellar joint of the rabbit was performed to evaluate whether osseointegration could be achieved in a one-stage surgical procedure. After three months, it was found that the screws used for anchorage of the prosthesis showed an average direct bone-to-implant contact of 60% in three selected consecutive threads on each side. The range was 40-90%. These figures correspond well with previously reported ones from bone anchored titanium fixtures. It was therefore concluded that osseointegration of dynamically loaded screws used for anchorage of a femoral-patellar joint prosthesis may be achieved in spite of the fact that no controlled healing period for the screws was observed.

Pulsatile intravenous growth hormone (GH) infusion to hypophysectomized rats increases insulin-like growth factor I messenger ribonucleic acid in skeletal tissues more effectively than continuous GH infusion

In this study we have investigated a possible functional role of the plasma pattern of GH in regulation of insulin-like growth factor I (IGF-I) mRNA in liver, skeletal muscle, and rib growth plate of the rat. Hypophysectomized male rats given T4 and glucocorticoid replacement therapy were equipped with indwelling jugular venous cannulae attached via swivels to a multichannel pumping system programmed to deliver human GH in a continuous or pulsatile (one pulse per 3 h) pattern for 5 days. At the end of the experiment, skeletal muscle, rib growth plates, and liver from intact and hypophysectomized rats were homogenized, and total nucleic acid was prepared. IGF-I mRNA was quantitated by solution hybridization assay using a RNA probe radiolabeled with [35S]UTP. Pulsatile treatment with GH in a dose of 1.5 U/kg.day induced a 3- to 5-fold increase in the levels of IGF-I mRNA in skeletal muscle and rib growth plates. In contrast, continuous infusion with GH was much less effective in these tissues. In the liver both continuous and pulsatile GH infusion significantly elevated the amount of IGF-I mRNA, and there was no significant difference between these two treatments. In the tissues studied similar results were obtained with a higher dose of GH (3.0 U/kg.day). Pulsatile GH treatment stimulated longitudinal bone growth more effectively than continuous GH treatment, confirming earlier studies. It is concluded that pulsatile GH treatment is more effective than continuous GH infusion in increasing IGF-I mRNA levels in rib growth plate and skeletal muscle, i.e. two major target organs for the anabolic effects of GH.

Characterization of the inhibitory effect of some antidepressant drugs on the outward transport of norepinephrine in the ischemic myocardium

The noradrenergic amine carrier has an important role in mediating the local release of norepinephrine (NE) during myocardial ischemia. The effects of the antidepressant or putative antidepressant drugs desipramine, 2-hydroxy desipramine, nisoxetine, (S)-oxaprotiline and (R)-oxaprotiline with respect to this release mechanism were investigated in the isolated rat heart submitted to total stop-flow ischemia and subsequent reperfusion. During the reperfusion phase a massive efflux of NE was observed, which was reduced in a concentration-dependent manner in the presence of the antidepressant drugs. The potency (pIC50) of the antidepressants in inhibiting the ischemia-induced NE release varied between 9.16 (desipramine) and 6.17 [(R)-oxaprotiline]. On the other hand, lidocaine (10 microM) or clonidine (1 microM) did not reduce the magnitude of the NE efflux. No attenuation in NE efflux could be detected when desipramine (0.1 microM) was present only during the reperfusion period. During repeated periods (3 x 20 min) of ischemia, desipramine (0.1 microM) reduced markedly the loss of NE. In another experiment in the isolated guinea pig heart, desipramine (0.1 microM) was also found to attenuate the ischemia-induced mobilization of NE to the same significant extent as in the isolated perfused rat heart. Chronic treatment (3 weeks) of rats with desipramine as well as acute administration of desipramine to rats (2 hr before the initiation of perfusion) caused a pronounced reduction in the ischemia-induced release of NE in the isolated perfused heart. In conclusion, these experiments strongly suggest that a major part of the ischemia-induced release of NE is mediated by the amine carrier associated with the noradrenergic nerve terminal membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional rehabilitation in Bangladesh--the importance of zinc

Our aim was to investigate whether zinc deficiency becomes apparent during nutritional rehabilitation and limits the rate of weight gain. Twenty-five severely malnourished children, who were admitted to the Children's Nutrition Unit in Bangladesh, were alternately allocated to two groups. Their mean dietary Zn intake was 3.7 mg/d and mean caloric intake greater than 150 kcal.kg-1.d-1; one group received a daily Zn supplement of 50 mg for 2 wk. During the first week, weight gain was similar in the two groups, but during the second week, weight gain was 73% more in the Zn-supplemented group (8.83 +/- 1.56 vs 5.09 +/- 1.62 g.kg-1.d-1). The 95% confidence limits were 0.88 less to 8.36 g.kg-1.d-1 more gain in children receiving Zn supplements. The results strongly suggest that Zn supplements are beneficial to severely malnourished children during nutritional rehabilitation. Polymorphonuclear (PMN) cell Zn increased in the group receiving Zn supplements (p less than 0.001), confirming that the Zn content of PMN cells reflects available Zn.

Implant fixation improved by close fit. Cylindrical implant-bone interface studied in rabbits

Cylindric titanium implants of three different diameters were inserted and stabilized in a 3.7-mm burr hole in the rabbit tibia. The purpose of the study was to investigate the interfacial reaction to screw- and cylinder-shaped implants, and to determine if there is a critical gap at the insertion between bone and implant that prevents direct cortical bone apposition on the implant. The study indicated that this critical gap approached zero.

A crucial role of ongoing anaerobic glycolysis in attenuating acute ischemia-induced release of myocardial noradrenaline

The myocardial energy requirements of the noradrenergic nerve terminal to retain its transmitter during acute myocardial ischemia were examined in the isolated perfused rat heart. In hearts perfused with glucose as exogenous substrate no increased release of noradrenaline (NA) could be detected during ischemia. In contrast, an increased efflux of NA was seen from glucose-perfused hearts when the glycolytic pathway was inhibited with 0.5 mM iodacetic acid. Accordingly, induction of ischemia in glycogen-depleted hearts (in the absence of exogenous substrate) or in hearts perfused with either lactate, pyruvate or acetate was also associated with a marked efflux of NA. However, no efflux was detected from glycogen-depleted hearts when glucose was present during the ischemic period. Uncoupling of oxidative metabolism with 0.1 mM 2.4-dinitrophenol did not cause any increased loss of NA during ischemia. In conclusion, these results demonstrate that severe restriction in coronary flow is accompanied by increased release of myocardial NA. Furthermore, maintainance of anaerobic glycolysis is of crucial importance for retention of the noradrenergic transmitter during ischemic conditions.

A two-site monoclonal enzyme immunoassay for pregnancy-associated alpha 2-glycoprotein

A two-site monoclonal enzyme immunoassay (MEIA) was developed for the determination of pregnancy-associated alpha 2-glycoprotein (PA alpha 2G) in serum. The minimum detectable level was 35 ng/ml. No immunochemical interaction with the closely related alpha 2-macroglobulin was found. Serum levels in 145 normal healthy males and non-pregnant females were 1.8 +/- 2.8 micrograms/ml (mean +/- SD), respectively, both significantly lower than previously reported. The distribution in the normal population was characteristically different when males and females were compared. No increase with age was found. During pregnancy, a significant increase in serum concentration was observed with average levels of 320 +/- 200 micrograms/ml at term (mean +/- SD), a 50-fold increase in concentration. As a tumor marker for breast and ovarian cancer, PA alpha 2G was found to be of no value. The present study emphasizes that a reevaluation of PA alpha 2G levels must be undertaken in order to assess the clinical and biological significance of this protein.

Early intraneuronal mobilization and deamination of noradrenaline during global ischemia in the isolated perfused rat heart

Isolated rat hearts were perfused according to the Langendorff technique and both extraneuronal uptake of noradrenaline and COMT were inhibited. The noradrenergic neurones were first prelabelled with 3H-(-)-noradrenaline (13 nmol/l). Thereafter the hearts were submitted to global ischemia (perfusion rate reduced from 5 up to 0.5 ml/min) for 60 min and subsequently reperfused for 5 min. The coronary effluent was continuously collected and analyzed for the appearance of 3H-noradrenaline and its metabolites. 1. Global ischemia was associated with an early release of 3H-noradrenaline. At reperfusion a brisk increase in the FRL of 3H-noradrenaline was observed which may indicate that, on severe restriction in coronary flow, perfusion of the tissue became heterogenous and thus partially masked the amount of 3H-noradrenaline released from the noradrenergic nerve terminals. Gradual reduction in coronary flow also progressively reduced (but did not abolish) the total formation of 3H-DOPEG. 2. The maximal efflux of 3H-noradrenaline was observed during the 1st min of reperfusion whereafter the efflux declined rapidly, indicating a wash-out of transmitter trapped in the extracellular space. The efflux of the lipophilic metabolite 3H-DOPEG, on the other hand, continuously increased during the reperfusion. This was due to both new formation and "wash-out" of 3H-DOPEG retained and/or distributed into the tissue during the period of restricted flow. 3. Neither a reduction of the extracellular calcium concentration (from 2.6 mmol/l to 0.1 mmol/l) nor the presence of the calcium entry blocker verapamil (250 nmol/l) reduced the efflux of 3H-noradrenaline seen during ischemia and reperfusion. 4. Desipramine (100 nmol/l) markedly reduced the ischemia-induced release of 3H-noradrenaline and simultaneously attenuated the formation of 3H-DOPEG. 5. A moderate reduction in the ischemia-induced mobilization of 3H-noradrenaline was seen in hearts perfused with 1 mumol/l reserpine, whereas the formation of 3H-DOPEG from such hearts was markedly higher than in corresponding controls. Only minor deviations from this pattern was observed when desipramine was present in addition to reserpine. It is concluded that a severe restriction in myocardial perfusion rate is associated with an enhanced net leakage of vesicular noradrenaline. This results in a rise of the free axoplasmic noradrenaline concentration which, in combination with an altered transmembrane sodium gradient, induces an increased local release of noradrenaline partly mediated by a calcium-independent, carrier-mediated outward transport.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential effects of growth hormone and insulin-like growth factor I on colony formation of epiphyseal chondrocytes in suspension culture in rats of different ages

The effect of human GH (hGH) and insulin-like growth factor I (IGF-I) on the colony formation of rat epiphyseal chondrocytes was studied in suspension culture. Chondrocytes from epiphyseal growth plates of the proximal tibia of 7-, 20-, and 28-day-old normal male rats were enzymatically isolated and cultured in the presence of 10% newborn calf serum in suspension stabilized with 0.5% agarose. The cloning efficiency (number of formed colonies per 1000 seeded cells) was 13.7 +/- 1.9, 3.2 +/- 0.6, and 3.5 +/- 0.4 for chondrocytes isolated from 7-, 20- and 28-day-old rats and cultured for 14 days, respectively. The colonies were classified according to size (colony diameter), and the number of colonies was estimated as a function of colony size (distribution of cloning efficiency). IGF-I (25-200 ng/ml) increased the total colony number among chondrocytes isolated from the three different age groups and particularly increased the number of small colonies. However, IGF-I did not significantly change the distribution of cloning efficiency as compared to the control group. hGH potentiated colony formation at concentrations of 10-80 ng/ml, but no stimulatory effect of hGH was apparent at a concentration of 160 ng/ml. GH caused an assymetric distribution of cloning efficiency that was significantly different from the control group due to an increased number of large colonies (diameter exceeding 80 microns). The differential effects of GH and IGF-I were apparent after an extended period of culture (28 days) at various concentrations of the peptides. These results show that GH as well as IGF-I induced colony formation among epiphyseal chondrocytes in suspension culture, although the effects of GH and IGF-I are different in terms of distribution of cloning efficiency. The observation that GH particularly potentiated the formation of large size colonies suggests that GH promotes the differentiation of prechondrocytes, or young chondrocytes as suggested earlier. The finding that IGF-I stimulation resulted in a higher proportion of small size chondrocyte colonies, compared to the control group, suggests that IGF-I stimulates epiphyseal chondrocytes at a later stage of differentiation.

Ischaemia-induced release of noradrenaline and creatine kinase in the isolated, working rat heart

In order to examine an early ischaemia-induced local release of myocardial noradrenaline (NA), the left coronary artery of the isolated working rat heart was ligated for periods varying between 7.5 min and 30 min, followed by reperfusion for 5 min. As perfusion substrate, glucose, lactate or both were used. In part of the experiments, hearts were pre-labelled with [3H]NA. Already after 7.5 min of ischaemia, an increased efflux of endogenous NA was observed in the perfusate at reperfusion, concomitant with a decrease in tissue NA content. This effect was most pronounced with lactate as substrate. Qualitatively similar effects were seen on [3H]NA efflux from labelled hearts. The combination of glucose and lactate as substrate markedly reduced (compared with lactate alone) the efflux of NA, whereas no such reduction was observed on the efflux of creatine kinase (CK). It is concluded that ischaemia is associated with an early local release of NA. Furthermore, ischaemia may induce different effects on the metabolic processes of the myocyte as compared with the adrenergic nerve ending.

Oestradiol increases baseline growth hormone levels in the male rat: possible direct action on the pituitary

The effect of oestradiol treatment on the secretion of growth hormone (GH) was investigated in normal unrestrained male rats with chronic i.v. cannulae and in hypophysectomized male rats with autotransplanted pituitaries. The effect of gonadectomy of normal rats on the plasma GH secretory pattern was also evaluated. Baseline plasma GH levels were elevated following estradiol treatment of normal male rats (1.5 mg kg-1 per 15 days). Gonadectomy of male rats also resulted in increased baseline GH levels, although the effect was less apparent than after oestradiol administration. The pulse height was not influenced by gonadectomy or oestradiol administration. In male rats with the pituitary autotransplanted to the kidney capsule, oestradiol caused a dose-dependent increase in plasma GH levels, while there was no such effect of testosterone. These results suggest that the stimulatory influence of oestradiol on baseline GH levels is, at least partly, due to a direct effect on the pituitary. Plasma prolactin levels were elevated in rats with pituitary transplants receiving oestradiol. It is concluded that oestrogen administration to normal male rats increases baseline plasma GH levels, possibly by an effect exerted directly at the pituitary level.

An experimental model for pharmacokinetic studies of monoclonal antibodies in human colonic cancer

An experimental model consisting of athymic rats carrying human colonic tumours from cell line LS 174T in both hind legs was used. 125I-labelled anti-carcinoembryonic antigen (anti-CEA) monoclonal antibodies were injected intra-arterially (i.a.), either alone (21 rats) or together with degradable starch microspheres (6 rats). As a control, an irrelevant antibody was injected i.a., alone (6 rats) or together with microspheres (3 rats). An intra-arterial injection was given on the side bearing one tumour in each rat, while the contralateral tumour served as an 'intravenous' control. The rats were submitted to external gamma measurements daily for four days. On the fourth day they were killed and pieces from the tumours and from various organs were examined by in vitro measurements. The results indicate strong expression of CEA in LS 174T cells grafted to athymic rats. No lasting enhancement of the tumour uptake was achieved by intra-arterial injection of antibodies as compared with the control tumours.

Enhanced uptake of intra-arterially injected anti-CEA monoclonal antibodies in human colonic cancer after mannitol infusion in an experimental model

In a previous report athymic rats carrying transplanted human colonic tumours from cell line LS 174T in both hind legs were injected intra-arterially (i.a.) with 125I-labelled anti-carcinoembryonic (anti-CEA) monoclonal antibodies. The i.a. injection was given on one side bearing a tumour in each rat, while the contralateral tumour served as an 'intravenous' control. In the same experimental model and treated in the same way, 10 rats were injected i.a. with anti-CEA monoclonal antibodies after an i.a. mannitol infusion. In both groups of rats external gamma measurements were performed daily for four days. On the fourth day the rats were killed and pieces of the tumours and of various organs were weighed and the activity was determined with a gamma-counter. The tumour uptake of antibodies was significantly enhanced after mannitol infusion.

Osseointegration of titanium implants

Forty-eight screws, six double cylindrical implants and six T-plates were inserted into the tibia or femur of 6 dogs. Two titanium screws were inserted into the proximal tibia of 5 patients to anchor a titanium mould. The implants were removed en bloc with adjacent bone tissue after 3 to 14 months. They were sectioned using a technique that allowed analysis of the intact tissue-to-metal specimens. Osseointegration, defined as a direct bone-to-implant contact without interposed soft tissue, was confirmed in all screw-shaped implants while the cylindres had only partial bone contact as did the T-plates. We conclude that osseointegrated implants may be applicable in joint reconstruction for arthrosis or rheumatoid arthritis.

Release of noradrenaline in myocardial ischemia--importance of local inactivation by neuronal and extraneuronal mechanisms

The mechanisms responsible for the local inactivation of noradrenaline (NA) released during myocardial ischemia were examined in the isolated perfused rat heart preloaded with 3H-NA. Two different types of ischemia were used: (a) 90% global flow reduction (global ischemia), and (b) ligation of the left coronary artery (regional ischemia). The coronary effluent was collected at different intervals during ischemia and reperfusion, and 3H-NA was separated from its tritiated metabolites using HPLC. During ischemia, a gradual increase in the efflux of 3H-NA was observed, which was accompanied by a shift from predominantly neuronal metabolism towards increased efflux of extraneuronally formed metabolites. During the first minute of reperfusion, the metabolic pattern of 3H-NA was not substantially changed as compared with that observed immediately before reperfusion, indicating a wash-out of 3H-NA and its tritiated metabolites accumulated in the tissue during the ischemic period. Addition of corticosterone to the perfusion medium (to inhibit extraneuronal uptake of 3H-NA) was associated with an increased efflux of 3H-NA during the ischemic period. In contrast, addition of the neuronal uptake blocker desipramine caused a decreased efflux of 3H-NA during ischemia. In conclusion, these experiments demonstrate an ischemia-induced release of myocardial NA, in all probability due to the recently proposed carrier-mediated efflux mechanism. The release is parallelled by an increasing extraneuronal inactivation of released transmitter.

Antigenic determinants of pregnancy-associated alpha 2-glycoprotein and alpha 2-macroglobulin defined by poly- and monoclonal antibodies

Human alpha 2-macroglobulin and pregnancy-associated alpha 2-glycoprotein (PA alpha 2G) share several physicochemical characteristics. By the use of unabsorbed or absorbed polyclonal antibodies to these antigens, the existence of common epitopes in these molecules were demonstrated in crossed immunoelectrophoresis. Two monoclonal antibodies out of 9 raised against purified PA alpha 2G were demonstrated to react with both antigens, indicating close immunochemical relatedness between these macroglobulins. The findings might have functional implications.

Objective quantification of tremor in conscious unrestrained rats, exemplified with 5-hydroxytryptamine-mediated tremor

To accomplish an objective quantification of tremor in conscious unrestrained rats, a registration device based on accelerometry was developed. Tremor intensity was continuously recorded by a small piezoresistive accelerometer (Egal 125-10D, Entran Devices) mounted on the back of the freely moving rat. The accelerometer was connected to a Grass Polygraph, where the analog signal was quantified as arbitrary marks/min by a 7P10 integrating unit. The integrated signals were then further analyzed by a desk-top computer (Luxor ABC-80). By analyzing tremor response to central serotonergic system activation, the reproductibility as well as the advantages and limitations of this recording system were demonstrated.

Gas exchange during mechanical ventilation

In an experimental model using a Servo-ventilator (Siemens-Elema, Sweden) oxygen consumption (V'O2) and carbon dioxide production (V'CO2) were measured at varying FIO2. Gas exchange was simulated by adding N2 or CO2 to the inspiratory line of the ventilator. Inspiratory and expiratory gases were collected in Douglas bags for analyses by a mass spectrometer. The residual standard deviation for the regression of measured V'O2 on predicted V'O2 was 14 ml/min and did not significantly differ from the line of identity. For V'CO2 the corresponding residual standard deviation was 3 ml/min. This regression line deviated by -3% from the line of identity.

Growth hormone (GH)-releasing factor (GRF) pretreatment enhances the GRF-induced GH secretion in rats with the pituitary autotransplanted to the kidney capsule

The long term in vivo effects of the recently characterized human pancreas GH-releasing factor, hpGRF (1-44) were studied in chronically cannulated unrestrained rats. In order to minimize the influence of endogenous hypothalamic GRF and somatostatin on the pituitary, the experiments were carried out in rats with the pituitary autotransplanted to the kidney capsule. The integrated GH release (mean +/- SE) in response to an iv injection of hpGRF (4 micrograms/kg) was markedly enhanced (P less than 0.01) by iv pretreatment with hpGRF every 8 h for 3 days (182 +/- 47 h X ng/ml) as compared to saline-pretreated controls (36 +/- 4 h X ng/ml). TRH pretreatment did not potentiate the effect of hpGRF (47 +/- 9 h X ng/ml). It is concluded that multiple administrations of hpGRF enhance the GH response to a subsequent hpGRF injection in the rat. Moreover, autotransplantation of the pituitary to the kidney capsule may supply a useful in vivo model for further studies on the effects of different modes of GRF administration on GH secretion.

Wash-out of noradrenaline and its metabolites by calcium-free reperfusion after ischaemia: support for the concept of ischaemia-induced noradrenaline release

The outflow of noradrenaline (NA) and its metabolites on reperfusion after 60 min of regional ischaemia in the isolated heart of the rat was not diminished when calcium was omitted from the reperfusion medium. The findings suggest a release of NA during ischaemia, washed-out at reperfusion.

Ischemia-induced noradrenaline release in the isolated rat heart: influence of perfusion substrate and duration of ischemia

To examine some of the characteristics of the local noradrenaline (NA) release in myocardial ischemia a study was made on Langendorff-perfused rat hearts, prelabelled with 3H-NA. The left coronary artery was ligated for 15, 30, 60 or 120 min, followed by 10 min of reperfusion. The coronary effluent was collected and analyzed for radioactivity to indicate release of 3H-NA. In some of the experiments the fraction of 3H-NA was determined. As substrate in the perfusion medium either glucose (11.1 mM) or sodium lactate (5.0 mM) was used. During the ischemic period there was a slight decrease in the outflow of radioactivity. However, reperfusion was associated with a rapid and marked outflow of radioactivity, including an increased fraction of 3H-NA, in the effluent. Compared to glucose as perfusion substrate, lactate caused a significantly higher (P less than 0.01) outflow of tritiated substances after 60 and 120 min of regional ischemia. With lactate there was an almost linear relationship between reperfusion efflux of 3H and duration of ischemia. With glucose, the reperfusion outflow increased less rapidly after a duration of ischemia longer than 15 min. It is concluded that the degree of local NA release in myocardial ischemia depends on both the duration of the ischemic period and the substrate used. Glucose attenuates the reperfusion outflow of NA, especially after longer periods of ischemia. The effect may be due to decreased myocardial cell damage with this substrate and/or a direct protection of the adrenergic nerve endings.

Exposure to and effects of glare from high mast lighting on workers at a timber terminal

High mast floodlighting at outdoor workplaces has economic advantages but suffers from shortcomings such as glare. This study was made to collect and evaluate data from a situation with glare from a physical and occupational health standpoint. When unloading timber, the worker's gaze is frequently directed upward, whereas conventional glare indexes for luminaires assume the gaze is diagonally downwards. It was found that reduced visual acuity could cause difficulty in normal working routines.

Effect of metabolic control and duration on exercise-induced albuminuria in diabetic teen-agers

Nineteen type I diabetic teen-agers without clinical signs of nephropathy with a duration of diabetes varying from 3 to 16.8 years were examined by a standardized exercise test for analysis of urinary excretion of albumin and beta 2-microglobulin. The patients were studied both in poor and improved (but not perfect), metabolic control as defined by HbA1c and blood glucose profiles, and the values were compared to those of 14 age-matched healthy controls. The controls showed no increase in albumin excretion rate during exercise as was found in diabetic patients. The albumin excretion rate during exercise was significantly correlated (p less than 0.05) to systolic blood pressure in the diabetic patients. Blood pressure in the diabetic patients was, however, similar to that of controls both at rest and during exercise. Urinary beta 2-microglobulin did not change during exercise. The urinary albumin excretion during exercise decreased significantly with improved metabolic control in diabetic patients, but the albumin excretion rate was not correlated with either blood or urinary glucose or diuresis during the exercise test. When metabolic control was improved there was a significant correlation between the increase in albumin excretion rate during exercise and the duration of diabetes, indicating that part of the exercise-induced albumin excretion might reflect irreversible morphological changes in the diabetic kidney. This test might therefore have a predictive value for diabetic nephropathy if performed during strict metabolic control.

ADP-ribosylation of the Mr 83,000 stress-inducible and glucose-regulated protein in avian and mammalian cells: modulation by heat shock and glucose starvation

ADP-ribosylation of proteins was analyzed by in vivo labeling of cells with [3H]adenosine, followed by separation of their protein components by two-dimensional isoelectric focusing/NaDodSO4 polyacrylamide gel electrophoresis. We show here that in several cell types of avian and mammalian origin the major [34H]adenosine acceptor in vivo is a polypeptide with a Mr of 83,000 and isoelectric point of approximately equal to 5.3. This polypeptide is identical to one of the stress-inducible and glucose-regulated proteins (here called SP83) previously described in avian and mammalian cells. Snake venom phosphodiesterase digestion of purified 3H-labeled SP83 releases 5'-AMP and a minor fraction of 2'-(5"-phosphoribosyl)-5-AMP. In vitro labeling with [32P]NAD+ of total cell lysates made in the presence of non-ionic detergents also results in incorporation of radioactivity into SP83. Both of these results strongly suggest that the modification is an ADP-ribosylation. Heat shock and glucose starvation of cells induce a rapid and extensive decrease in the incorporation of ADP-ribose into SP83, suggesting that ADP-ribosylation may be important for the regulation of the function of this protein.

A monoclonal antibody-enzyme immunoassay for serum carcinoembryonic antigen with increased specificity for carcinomas

A two-site monoclonal antibody-enzyme immunoassay (MEIA) for carcinoembryonic antigen (CEA) was developed that uses two monoclonal anti-CEA antibodies, which recognize two different epitopes in the peptide moiety of CEA. The assay was sensitive to 0.5 micrograms/liter and had a measuring range of 0.5-200 micrograms of CEA per liter. It was highly specific inasmuch as none of three known CEA-related substances, "nonspecific crossreacting antigens 1 and 2" (NCA-1 and NCA-2) and biliary glycoprotein I (BGP I), reacted in the assay. NCA-2 (meconium antigen) is very similar to CEA. None of five commercially available CEA assays were able to differentiate between CEA and NCA-2. With one exception (colon), normal tissue extracts did not react in the MEIA even when tested at very high concentrations. Sera from a total of 180 healthy individuals and patients with malignant and nonmalignant disease were analyzed for CEA levels by using the MEIA and in parallel a conventional radioimmunoassay. A significant increase in specificity for carcinomas was obtained with the MEIA. This was essentially due to a decrease of MEIA CEA values in sera from patients with nonmalignant disease. The CEA values in the group of carcinoma patients (colon, pancreas, lung, and breast) were the same in the two assays.

On the dynamics of the microfilament system in HeLa cells

We measured the pools of unpolymerized and filamentous actin in homogenates of HeLa cells made in several different lysis buffers, as well as after treatment of cells with a variety of chemicals or trypsin, and after adenovirus (type 2) infection. This was possible when a series of factors concerning the basic culture conditions were kept constant: e.g., serum type used, serum batch, cell density, time after subcultivation of cells, and buffering substance in the medium. Homogenates from untreated cells usually contain 35-45 percent of the total actin in an unpolymerized form. With some batches of cells this number can be as high as 50 percent. In sparse cultures (3 x 10(4) cell/cm(2)), HeLa cells contain approximately 10 pg actin/cell, while the corresponding number is only 5 pg in dense cultures (3 x 10(5) cells/cm(2)). Treatment of cells with cytochalasin B increases the pool of unpolymerized actin by approximately 30-40 percent, while colchicine decreases the fraction of unpolymerized actin by 20 percent. The oxidant diamide increases the filamentous actin pool 25-50 percent. Glucose, sodium azide, dinitrophenol, serum starvation, or thymidine treatment does not affect the distribution between unpolymerized and filamentous actin to any significant extent. Trypsin and EDTA induced rounding up of cells but did not change the actin distribution. The distribution of actin between G- and F-forms was unchanged after adenovirus infection. These results show that significant changes in the actin pools can be induced in nucleated cells. However, several treatments which alter the morphology and motility of cells are not accompanied by an alteration in the G-/F-actin ratio.