Analysis of the first intron of TNFB gene by NcoI RFLP in Koreans

The tumor necrosis factor B (TNFB) gene is closely liked with tumor necrosis factor A (TNFA) gene between the HLA-B and C2 genes on chromosome 6p21.3. Several genetic variabilities at the human TNFB loci have been identified, which are the NcoI restriction fragment length polymorphism (RFLP) in the first intron, amino acid substitution at codon 26 of exon 3 and EcoRI RFLP in untranslated exon 4. The NcoI RFLP of TNFB gene gives two allelic fragments of 238/259 bp and 497 bp, corresponding to TNFB*1 and TNFB*2 alleles, respectively. To investigate the frequency of NcoI RFLP in the first intron of TNFB in Koreans and to compare to that of other ethnic population, genomic DNAs were extracted from leukocytes of 305 unrelated healthy Koreans and amplified the first intron of TNFB gene by PCR. The phenotype frequencies of NcoI RFLP such as TNFB* 1/TNFB*1, TNFB*1/TNFB*2 and TNFB*2/TNFB*2 were 8.6% (n = 26), 45.2% (n = 138) and 46.2% (n = 141), respectively. The estimated allele frequencies for TNFB*1 and TNFB*2 were 0.3115 and 0.6885, respectively. The observed and expected frequencies were in good agreement with the Hardy-Weinberg's equilibrium. The heterozygosity revealed 45.2% and the allele frequencies of NcoI RFLP of TNFB in Koreans were observed comparatively similar to those of other ethnic groups.

Correcting for measurement error in the analysis of case-control data with repeated measurements of exposure

The authors present a technique for correcting for exposure measurement error in the analysis of case-control data when subjects have a variable number of repeated measurements, and the average is used as the subject's measure of exposure. The true exposure as well as the measurement error are assumed to be normally distributed. The method transforms each subject's observed average by a factor which is a function of the measurement error parameters, prior to fitting the logistic regression model. The resulting logistic regression coefficient estimate based on the transformed average is corrected for error. A bootstrap method for obtaining confidence intervals for the true regression coefficient, which takes into account the variability due to estimation of the measurement error parameters, is also described. The method is applied to data from a nested case-control study of hormones and breast cancer.

Streptomyces seoulensis sp. nov

The taxonomic position of an actinomycete strain isolated from Korean soil was examined by a polyphasic approach. The isolate, designated IMSNU-1, was clearly assigned to the genus Streptomyces on the basis of morphological and chemotaxonomic data. The test strain was the subject of a probabilistic identification study using the identification matrices generated by Langham et al. (J. Gen. Microbiol. 135:121-133, 1989) and found to be marginally close to clusters 19 and 39. An almost complete 16S rRNA gene (rDNA) sequence was obtained for the test strain and compared with those of representative streptomycetes. 16S rDNA sequence data not only support the strain's membership in the genus Streptomyces but also provide strong evidence that our isolate is genealogically distant from representatives of clusters 19 and 39, forming a separate phyletic line in a clade encompassed by streptomycetes. It is therefore proposed from the polyphasic evidence that strain IMSNU-1 be classified in the genus Streptomyces as Streptomyces seoulensis sp. nov.

NcoI restriction fragment length polymorphism at -308 of the tumor necrosis factor alpha (TNFA) promoter region in Korean

Tumor necrosis factor alpha (TNFA) is a cytokine, which is secreted from activated macrophage, with a broad range of biological activities. The gene encoding TNFA is located in tandem with the TNFB gene within the HLA complex on chromosome 6p21.3. We detected a single base polymorphism in the human TNFA gene promoter region in 300 unrelated Korean individuals. The TNFA promoter region which showed a G to A transition at position of -308 was investigated by NcoI restriction fragment length polymorphism analysis. A biallelic polymorphism of TNFA gene showed fragments of 87/20 bp and 107 bp acting as TNFA*1 allele and TNFA*2 allele, respectively. The allele frequencies of TNFA*1 and TNFA*2 were 0.8783 and 0.1217, respectively. The 21.7% of heterozygosity was observed. No association between promoter region phenotypes of TNFA and the first intron phenotypes of TNFB was observed in Korean. Allele frequencies of Koreans were compared with that of Europeans.

Three-vessel view of the fetal upper mediastinum: an easy means of detecting abnormalities of the ventricular outflow tracts and great arteries during obstetric screening

The three-vessel view is a transverse view of the fetal upper mediastinum is as simple to obtain as the four-chamber view. It demonstrates the main pulmonary artery, ascending aorta and superior vena cava in cross- or oblique sections. The purposes of this study were to describe the normal anatomy of the three-vessel view and to analyze what anatomical changes would occur in this view when there are lesions of the ventricular outflow tracts and/or great arteries. Sonograms of 29 fetuses with lesions involving the ventricular outflow tracts and/or great arteries were reviewed. Three-vessel views were evaluated in terms of vessel size, number, arrangement and alignment. Twenty-eight of 29 fetuses showed an abnormal three-vessel view that included abnormal vessel size (n = 12), abnormal alignment (n = 8), abnormal arrangement (n = 7) and abnormal vessel number (n = 3). The vessel size was abnormal in obstructive lesions of the right (n = 4) or the left (n = 8) side of the heart. An abnormal alignment was seen in tetralogy of Fallot (n = 6) and double-outlet right ventricle (n = 2) that showed anterior displacement of the aorta. An abnormal arrangement was seen in complete (n = 4) and corrected (n = 1) transposition, double-outlet right ventricle (n = 1) and pulmonary atresia with ventricular septal defect (n = 1). Only two vessels were seen in truncus arteriosus (n = 1). Four vessels were seen in persistent left superior vena cava (n = 2). A fetus with pulmonary atresia and intact ventricular septum showed a normal three-vessel view. In conclusion, most of the lesions involving the ventricular outflow tracts and/or great arteries showed an abnormal three-vessel view.

In vitro and in vivo activities of LB10522, a new catecholic cephalosporin

In vitro activity of LB10522 was compared with those of cefpirome, ceftazidime, ceftriaxone, and cefoperazone against clinical isolates. Against gram-positive bacteria, LB10522 was most active among the compounds tested. It was fourfold more active than cefpirome against methicillin-susceptible Staphylococcus aureus and Enterococcus faecalis. LB10522 was highly effective against most members of the family Enterobacteriaceae tested. Ninety percent of isolates of Escherichia coli, Klebsiella oxytoca, Proteus vulgaris, Proteus mirabilis, and Salmonella spp. were inhibited at a concentration of < or = 0.5 micrograms/ml. These activities were comparable to those of cefpirome. Against Pseudomonas aeruginosa, LB10522 with a MIC at which 90% of the isolates are inhibited of 2 micrograms/ml was 16- and 32-fold more active than ceftazidime and ceftazidime against systemic infections caused by Staphylococcus aureus giorgio, Streptococcus pneumoniae III, Pseudomonas aeruginosa 1912E, Escherichia coli 851E, Proteus mirabilis 1315E, Serratia marcescens 1826E, and Acinetobacter calcoaceticus Ac-54. LB10522 was very resistant to hydrolysis by various beta-lactamases such as TEM-3, TEM-7, SHV-1, FEC-1, and P-99. LB10522 did not induce beta-lactamase in Enterobacter cloacae 1194E, although most of the reference cephalosporins acted as inducers of beta-lactamase in this strain. Time-kill study showed that LB10522, at concentrations of two or four times the MIC, had a rapid bactericidal activity against Staphylococcus aureus 6538p, Escherichia coli 851E, and Pseudomonas aeruginosa 1912E.

In vitro and in vivo evaluations of LB20304, a new fluoronaphthyridone

In vitro activity of LB20304 against 1,231 clinical isolates was evaluated and compared with those of ciprofloxacin, sparfloxacin, lomefloxacin, and ofloxacin. LB20304 demonstrated the most potent activity against gram-positive bacteria. It was 32- to 64-fold more active than ciprofloxacin against methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus, methicillin-resistant Staphylococcus epidermidis, and Streptococcus pneumoniae (penicillin G resistant). LB20304 was also highly active against most members of the family Enterobacteriaceae. Its activity was more potent than those of sparfloxacin, ofloxacin, and lomefloxacin and comparable to that of ciprofloxacin. The protective activities of LB20304 against systemic infections caused by gram-positive bacteria in mice were superior to those of ciprofloxacin and sparfloxacin. Against infections by gram-negative bacteria, LB20304 was slightly less active than ciprofloxacin.

In-vitro and in-vivo antibacterial activity of LB10517, a novel catechol-substituted cephalosporin with a broad antibacterial spectrum

LB10517 is a new injectable cephalosporin with a broad spectrum of antibacterial activity against Gram-positive and Gram-negative bacteria. LB10517 inhibited 90% of methicillin-susceptible Staphylococcus aureus (MSSA) at 0.25 mg/L (MIC90), and was 8-fold more active than cefpirome. LB10517 was two- or four-fold more active than cefpirome against methicillin-susceptible Staphylococcus epidermidis (MSSE), Streptococcus pyogenes and Enterococcus faecalis. Both methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) were highly resistant to all compounds. LB10517 activity against most Enterobacteriaceae was comparable to or greater than that of cefpirome, and it also showed high activity against Pseudomonas aeruginosa. In a mouse septicaemia model, LB10517 exhibited excellent protective effects. In a respiratory tract infection model, the protective effect of LB10517 was comparable to that of cefpirome and ceftazidime. It was highly stable to hydrolysis by beta-lactamases, showing better physiological efficiency for TEM-9 than the other test compounds. LB10517 had the most potent antibacterial activity against beta-lactamase producing resistant strains. LB10517 did not induce beta-lactamase production in Enterobacter cloacae 1194E.

Study design and sample size considerations for half-life studies

Most studies on the half-lives of environmental contaminants have been based on small sample sizes and a limited number of repeated measurements. In this paper, we address issues of study design and sample size for half-life studies. Useful guidelines are provided for choosing the number of repeats and the optimal time interval between repeats for estimating an individual's half-life with a given level of precision, while minimizing the cost of the study. In addition, sample size and power considerations for studies comparing two population half-lives are investigated. An example is presented using data from a study on polychlorinated biphenyls and breast cancer.

Several forms of callitachykinins are distributed in the central nervous system and intestine of the blowfly Calliphora vomitoria

We have examined the distribution of two tachykinin-related neuropeptides, callitachykinin I and II (CavTK-I and CavTK-II), isolated from whole-animal extracts of the blowfly Calliphora vomitoria. Extracts of dissected brains, thoracic-abdominal ganglia and midguts of adult blowflies and the entire central nervous system of larval flies were analysed by high performance liquid chromatography (HPLC) combined with enzyme-linked immunosorbent assay (ELISA) for the presence of CavTKs. To identify the two neuropeptides by HPLC, we used the retention times of synthetic CavTK-I and II as reference and detection with an antiserum raised to locustatachykinin II (shown here to recognise both CavTK-I and II). The brain contains only two immunoreactive components, and these have exactly the same retention times as CavTK-I and II. The thoracic-abdominal ganglia and midgut contain immunoreactive material eluting like CavTK-I and II as well as additional material eluting later. The larval central nervous system (CNS) contains material eluting like CavTK-I and II as well as a component that elutes earlier. We conclude that CavTK-I and II are present in all assayed tissues and that additional, hitherto uncharacterised, forms of tachykinin-immunoreactive material may be present in the body ganglia and midgut as well as in the larval CNS. An antiserum was raised to CavTK-II for immunocytochemistry. This antiserum, which was found to be specific for CavTK-II in ELISA, labelled all the neurones and midgut endocrine cells previously shown to react with the less selective locustatachykinin antisera. It is not clear, however, whether CavTK-I and II are colocalised in all LomTK-immunoreactive cells since there is no unambiguous probe for CavTK-I.

Lysozyme acts as a chemorepellent and secretagogue in Paramecium by activating a novel receptor-operated Ca++ conductance

Using combined intracellular recordings and behavioral bioassays, it was found that lysozyme has two different effects in Paramecium, depending upon the concentrations used. At low concentrations (0.5 mM to 1.0 microM) it acts as an effective chemorepellent that causes reliable electrophysiological changes. Lysozyme-induced somatic depolarizations, isolated by blocking K+ channels with Cs-TEA, showed concentration dependencies that were well correlated with chemorepulsion. Ion dependency experiments showed that these were Ca++ based depolarizations. Addition of either Na+ or Mg++ improves chemorepulsion by providing additional depolarizations. Both the depolarizations and chemorepulsion were blocked by 10 microM neomycin, suggesting that the depolarization is necessary for this chemosensory transduction event. At higher concentrations (100 microM), lysozyme is a secretagogue. A transient inward current, recorded in Ca++ alone solutions with Cs-TEA present, was seen in response to high lysozyme concentrations. The amplitude of this inward current was well correlated with exocytosis. Addition of neomycin (1.0 mM) eliminated both the inward current and exocytosis, suggesting a causal relationship. Neither amiloride or W-7, compounds previously suggested to affect the electrophysiological responses to secretagogues, had any significant effects. The mucopolysaccharide hydrolysis activity of lysozyme was not required for any of these responses. We propose that Paramecium have a high affinity receptor on the body plasma membrane that responds to either lysozyme or a related compound to cause an increase in a novel body Ca++ conductance. This receptor-operated Ca++ conductance causes membrane depolarization and chemorepulsion at low concentrations and triggers a sufficient Ca++ influx at high concentrations to cause exocytosis.

Estimating the reliability of an exposure variable in the presence of confounders

In this paper we discuss estimation of the reliability of an exposure variable in the presence of confounders measured without error. We give an explicit formula that shows how the exposure becomes less reliable as the degree of correlation between the exposure and confounders increases. We also discuss biases in the corresponding logistic regression estimates and methods for correction. Data from a matched case-control study of hormone levels and risk of breast cancer are used to illustrate the methods.

Inductive effect of ginsenoside-Rg1 on tyrosine aminotransferase gene expression in rat primary hepatocyte cultures

Ginsenoside-Rg1 (G-Rg1) present in the roots of Panax ginseng (C. A. Meyer) has been shown to induce the enzyme activity of tyrosine aminotransferase (TAT) EC(2.6.1.5) in rat hepatocyte cultures. Thus, we investigated whether the inductive effect of G-Rg1 may act through glucocorticoid receptor- or cAMP-mediated action mechanism in the hepatocyte cultures. G-Rg1 induced the TAT activity by 2-fold with a similar time course to that of dexamethasone in the cell cultures. This effect of G-Rg1 was abolished to the basal level when RU486, a specific glucocorticoid antagonist was added to 10(-5)M. Furthermore, the additive effect of G-Rg1 and dexamethasone was inhibited as well by RU486. G-Rg1 and dibutyryl-cAMP (Bt2-cAMP) also revealed an additive effect but this additive effect was inhibited only to the G-Rg1-induced level by Rp-cAMPS, a specific inhibitor of protein kinase A. From these results, we suggest that the action mechanism of G-Rg1 leading to the induction of TAT activity may be mediated through glucocorticoid receptor binding and may not directly act through cAMP-mediated induction mechanism.

Sources of variability in waist and hip measurements in middle-aged women

The reliability of single measurements of waist and hip circumference and the ratio of waist circumference to hip circumference (a widely used measure of body fat distribution) has not been fully examined. The authors analyzed measurements of waist and hip circumference, as well as self-reported weight and height, repeated 3-6 times between 1986 and 1991 among 1,851 participants in the New York University Women's Health Study. Quetelet index (weight (kg)/height (m)2) was positively correlated with waist circumference (r = 0.88), hip circumference (r = 0.89), and waist/hip ratio (r = 0.52). Mean weight was positively correlated with the within-subject variance of waist circumference (r = 0.27) and, to a lesser degree, with the within-subject variance of hip circumference (r = 0.08) and waist/hip ratio (r = 0.10). The within-subject variance of weight was positively correlated with the within-subject variance of waist (r = 0.30) and hip (r = 0.23) measurements, and less so with waist/hip ratio (r = 0.05). Intraclass correlations for waist, hip, and waist/hip ratio were 0.89, 0.81, and 0.74, respectively; adjustment for Quetelet index reduced the intraclass correlations for waist and hip measures by 33% and 48%, respectively. Such adjustment can provide a more realistic determination of the reliability associated with an exposure variable in the design and analysis of studies investigating the relation between body fat distribution and disease.

Analyzing doubly censored data with covariates, with application to AIDS

This paper proposes a method for incorporating covariate information in the analysis of survival data when both the time of the originating event and the failure event can be right- or interval-censored. This method generalizes the one-sample estimation results of De Gruttola and Lagakos (1989, Biometrics 45, 1-11) by allowing the distribution of time between the two events to be a function of covariates under a proportional hazards model. Estimates for the model coefficients, as well as the underlying distributions, are obtained by an iterative fitting procedure based on Turnbull's (1976, Journal of the Royal Statistical Society, Series B 38, 290-295) self-consistency algorithm in combination with the Newton-Raphson algorithm. The method is illustrated with data from a study of hemophiliacs infected with the human immunodeficiency virus.

HIV risk-related sexual behaviors among heterosexuals in New York City: associations with race, sex, and intravenous drug use

OBJECTIVE

To investigate the relationship between heterosexual behaviors associated with HIV infection and ethnicity, sex, and intravenous drug use.

METHODS

Subjects were recruited from Bellevue Hospital Center, New York City between 1986 and 1989, and interviewed about sexual behaviors and intravenous drug use. Analyses were based on 1561 black, white, or Hispanic individuals who reported having sexual contact with a member of the opposite sex.

RESULTS

Twenty-seven per cent of the study population were black, 43% Hispanic, and 31% white. Blacks were more likely than whites or Hispanics to have initiated sexual intercourse at an early age, and to have had a sexually transmitted disease. Sex with a female drug user was more common among white men, and contact with a prostitute more frequent among Hispanic men. Among the women, Hispanics had fewer sexual risk factors overall than whites or blacks. Use of barrier contraceptives was uniformly low across all ethnic groups. Intravenous drug use was significantly associated with sexual risk-taking. Women were more likely than men to have an intravenous drug-using (IVDU) sexual partner.

CONCLUSIONS

The large prevalence of high-risk sexual practices observed in this study emphasizes the continuing need to target AIDS prevention programs at those at highest risk of heterosexually transmitted HIV: racial minorities, IVDU, and their sexual partners.

Pulse oximetry and peak flow as indicators of wheezing severity in children and improvement following bronchodilator treatments

This study examined the changes from the initial peak flows and oxygen saturations (OSAT) of wheezing children at presentation to the emergency department through their treatment in the emergency department. Data was collected prospectively on 785 patients 5 to 20 years of age during an 11-month period from November 1, 1990, to September 30, 1991. Both the initial OSAT and peak flows were correlated with the number of bronchodilator treatments required in the emergency department and with the need for hospitalization. Both the initial OSAT and the peak flows had a limited ability to predict the need for hospitalization. Oxygen saturation appears to be a valid measure of wheezing severity and is more easily obtained in children of all ages. Following bronchodilator treatment, peak flow results in a larger quantitative improvement than OSAT; however, this difference does not appear to have any significant advantage. Aerosolized albuterol and subcutaneous epinephrine resulted in a similar degree of improvement as measured by peak flow and by oxygen saturation, with clinically similar changes in heart rate.

Identification of sphingomyelin turnover as an effector mechanism for the action of tumor necrosis factor alpha and gamma-interferon. Specific role in cell differentiation

The biochemical signaling mechanisms involved in transducing the effects of tumor necrosis factor alpha (TNF alpha) and gamma-interferon (gamma-IFN) on leukemia cell differentiation are poorly defined. Recent studies established the existence of a sphingomyelin cycle that operates in response to the action of vitamin D3 on HL-60 cells and that may transduce the effects of vitamin D3 on cell differentiation (Okazaki, T., Bell, R., and Hannun, Y. (1989) J. Biol. Chem. 264, 19076-19080). The effects of TNF alpha and gamma-IFN on sphingomyelin turnover were determined, and the specificity and role of sphingomyelin hydrolysis in HL-60 human promyelocytic leukemia cells with 20% hydrolysis of sphingomyelin at 15 min, 40% hydrolysis at 30-60 min, and return to base line at 2 h. The hydrolyzed sphingomyelin (18 pmol/nmol total phospholipid) was accompanied by the concomitant generation of ceramide (11.2 pmol/nmol total phospholipid). gamma-IFN also caused reversible hydrolysis of sphingomyelin with onset at 1 h and peak effect at 2 h. This sphingomyelin cycle appeared to be specific to the monocytic pathway of HL-60 differentiation, since it was not activated by retinoic acid or dibutyryl cAMP, inducers of granulocytic differentiation, nor with phorbol myristate acetate, an inducer of macrophage-like differentiation. Addition of synthetic ceramide or bacterial sphingomyelinase induced monocytic differentiation of HL-60 cells. Cell-permeable ceramide also caused prompt down-regulation of mRNA for the c-myc protooncogene. The time course of c-myc down-regulation was consistent with the action of ceramide as the mediator of TNF alpha action. These results suggest that sphingomyelin turnover may be an important signaling mechanism transducing the actions of TNF alpha and gamma-IFN with specific function in cell differentiation.

Estimating the infectivity of HIV from partner studies

The main sources of data for estimating infectivity of the human immunodeficiency virus (HIV) come from studies of the susceptible partners of individuals known to be infected with HIV. Estimation of infectivity from these studies is complicated by limitations imposed by the sampling designs. This paper reviews three sampling schemes that have been used in partner studies and, for each, proposes methods for estimating various theoretic models for infectivity. The methods, as well as procedures for checking goodness-of-fit, are illustrated using data from a study by Peterman and colleagues.

Imipramine binding in depressed patients with psychogenic pain

Imipramine binding to platelet membranes from depressed patients was analyzed. The patients were divided into two groups: one with depression alone, another with depression and psychogenic pain. The depressed patients with psychogenic pain had lower imipramine binding than the depressed patients without pain.

Human deoxycytidine kinase: kinetic mechanism and end product regulation

The kinetic properties of the monomeric deoxycytidine kinase (EC 2.7.1.74) from leukemic human T-lymphoblasts have been investigated. The results of steady-state initial-rate kinetic analysis and product inhibition studies at pH 7.5 and 37 degrees C indicate that substrate binding follows an ordered sequential pathway, with the magnesium salt of ATP being the first substrate to bind and dCMP the last product to dissociate. At subsaturating substrate concentrations, dCMP produced competitive inhibition against ATP, while against varied deoxycytidine concentrations dCMP exhibited mixed-type inhibition. ADP produced noncompetitive inhibition against either substrate. The limiting Km values for deoxycytidine and MgATP were 0.94 and 30 microM, respectively. The end product inhibitor dCTP exhibited competitive inhibition against varied ATP concentration, with a dissociation constant estimated to be 0.7 microM when extrapolated to zero ATP concentration. dCTP was purely noncompetitive against varied deoxycytidine concentration. On the basis of these kinetic results, and on the strong and specific inhibition by dCTP, it is proposed that this end product functions as a multisubstrate analogue, with its triphosphate group binding to the phosphate donor site of the enzyme and its deoxycytidine moiety overlapping and binding to the deoxynucleoside site in a highly specific manner.

Affinity purification of human deoxycytidine kinase: avoidance of structural and kinetic artifacts arising from limited proteolysis

Homogeneous deoxycytidine kinase has been isolated from leukemic human T-lymphoblasts by affinity chromatography based on a multisubstrate analog, deoxycytidine 5'-adenosine 5"'-P1,P4-tetraphosphate (dCp4A). Chromatography of extract treated with protease inhibitors yielded a monomeric polypeptide, inasmuch as the Mr of the native protein, 59,300, is comparable to the value of 52,000 from sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric pH was 6.1. But, enzyme isolated without protease inhibitors exhibited two fragments of Mr = 30,000 and 33,000, suggesting that proteolytic cleavage of the parental polypeptide had occurred during affinity chromatography. Both the parental and proteolyzed enzymes phosphorylated deoxyadenosine and deoxyguanosine, as well as deoxycytidine. However, the proteolyzed enzyme had an increased apparent Km for deoxycytidine. In consequence of this, a mixture of the two forms produced bimodal kinetic plots, whereas linear kinetics were displayed by each form alone.

Kinetics of the efflux of 3H-norepinephrine from rabbit irides

The pigment cell dependent accumulation of 3H(-)-norepinephrine (1 mumol/l) was studied in rabbit irides. Albino irides served as controls. Neuronal uptake, deamination and O-methylation of 3H(-)-norepinephrine were reduced by desipramine, pargyline and U-0521, respectively. Both albino and pigmented irides accumulated the catecholamine from the incubation medium. At 37.5 degrees C and 120 min of incubation, tissue/medium ratios for pigmented and albino irides were 10.70 and 4.30 ml/g respectively. At 0 degrees C, the accumulation of 3H(-)-norepinephrine in the albino iris was abolished, while the pigmented iris accumulated significant amounts. The tissue/medium ratio was approximately 3 ml/g. When irides were loaded with 1 mumol/l of 3H(-)-norepinephrine for 60 min the drug distributed into four different compartments. Most of the pigment cell dependent binding was associated with compartments III and the "bound fraction". The amount bound in these compartments was 73% of total accumulation. In pigmented irides obtained from reserpine-pretreated rabbits the total binding was reduced to 64% of that in pigmented control irides. The half times for efflux from pigmented iris were 1.2 min, 10.7 min and 94.8 min, respectively, for compartments I, II, and III. Irides were loaded with 3H(-)-norepinephrine in normal physiological salt solution and rates of efflux were studied in Ca2+-free medium. In either albino or pigmented iris, the late efflux declined more slowly compared to that from the control irides. When pigmented irides were loaded with a low concentration of 3H(-)-norepinephrine, the displacement of the labeled amine was equal by each stereoisomer of norepinephrine. Results are discussed in relationship to the pigment cell-dependent uptake of the catecholamine.

Alpha-adrenoreceptor-related dissociation constants and intrinsic efficacies of stereoisomers of epinephrine

THe alpha-adrenoreceptor-related dissociation constant and intrinsic efficacy of the stereoisomers of epinephrine were determined on the rabbit aortic strip. (-)-Epinephrine showed higher affinity than (+)-epinephrine or the desoxy analogue epinine. Efficacy of (+)-epinephrine relative to (-)-epinephrine was low (relative efficacy, er = 0.44). Epinephrine had about the same affinity and efficacy as (+)-epinephrine. When the alpha-adrenoreceptors were protected against dibenamine by an equimolar concentration of the isomers, (-)-epinephrine was found to be more effective than (+)-epinephrine or epinine. These results suggest that the stereoisomers of catecholamines differ not only in affinity but also in intrinsic efficacy.