Experimental Biology and Medicine

The absolute cholesterol content and rate of cholesterol synthesis was compared in rat ventral prostates obtained from adult normal and castrated rats. Cholesterol content and synthesis reduces to about 8–12% in the ventral prostate of castrated animals as compared to normal rats. Daily testosterone injections to castrated rats elicits a sharp increase in cholesterol content which correlates with an increase in prostate weight. The rate of cholesterol synthesis per microgram of prostatic DNA increases steeply 2 days after testosterone administration and then goes down and reaches a steady state after 5 days.

ACTH secretion by isolated pituitary cells is stimulated both by HME-CRF and DBC, and when given in combination, the two secretagogues interact synergistically. Although the mechanism of this interaction is unknown, the potentiating effect of DBC is displayed without an apparent time lag and persists after removal of the cyclic nucleotide. Corticosterone inhibits ACTH secretion induced by HME-CRF and DBC, acting alone or in combination. The implications of these findings are discussed.

The authors are grateful to Beth Wiblin Portanova and James Roe for their expert technical assistance.

Mean plasma prolactin levels obtained from male rats following anesthesia with ketamine, decapitation or via indwelling venous catheters were not significantly different although a larger variance was found in the samples obtained via catheters. Ketamine, at anesthetic doses, did not affect the increases in prolactin produced by reserpine or α-methylparatyrosine. Ketamine, at various doses, did not potentiate the effect of subthreshold doses of 5-hydroxytryptophan on prolactin secretion. Thus, ketamine would appear to be a suitable anesthetic for use in studies of prolactin secretion in male rats. Further studies in female rats are required.

Supported in part by grant nos. USPHS MH 30938, 29206, and RCSA MH 47808 to HYM.

These results indicate that urate secretion is inhibited by PZA and that the degree of inhibition is dose dependent. In the highest dose tested (1.6 mM/kg body wt/hr), PZA not only inhibits secretion but also inhibits urate absorption. Thus, PZA appears to inhibit both urate secretion and reabsorption. The inhibition of these processes is dose dependent but not necessarily of equal sensitivity.

These studies were presented in part to the American Federation for Clinical Research, Southern Section meeting, New Orleans, LA, January 27–29, 1977, and national meeting, Washington, D.C., April 30-May 2, 1977, and have appeared in abstract form in Clin. Res. 24: 416A, 1976. The studies were supported in part by a Clinical Investigator award to Dr. Weinman and an Associate Investigator award to Dr. Frankfurt from the Veterans Administration, and were performed while Dr. Frankfurt was a Fellow in Nephrology of Baylor College of Medicine. Pyrazinoic acid was kindly supplied by Dr. George Fanelli of the Merck Institute. The authors gratefully acknowledge the technical assistance of D. Steplock, L. Hawk and S. Sansom and the secretarial assistance of P. Dunham. Dr. Wadi N. Suki provided valuable guidance and advice.

Both the laboratory adapted Auburn strain and a recently isolated wild-type strain of channel catfish herpesvirus (CCV) were found to be inhibited by phosphonoacetic acid (PAA) when replicated in catfish cell cultures. The inhibition of virus cytopathic effect by PAA exhibited a direct relationship between the multiplicity of infection and amount of drug required. However, in this poikilothermic system up to 20 times the amount of PAA required for inhibition of homeothermic herpesvirus systems was found necessary to inhibit CCV cytopathology.

Many studies have shown that estrogen increases the blood flow to the pregnant and non-pregnant uterus (1-3), but the mechanism by which this vasodilation occurs has not been determined.

It has been postulated that prostaglandins may mediate this vasodilation. Prostaglandins have been shown to play a role in the regulation of blood flow in the pregnant sheep uterus (4) and some studies have indicated that prostaglandins affect blood flows in non-pregnant uteri (5). Some investigators have also reported finding increased prostaglandin synthesis in uterine tissue following estrogen treatment (6, 7).

The following experiment was designed to study the response of the uterine vasculature to estrogen treatment in the rabbit and to determine if prostaglandins are involved in this response through the use of the known prostaglandin synthetase inhibitors, indomethacin and meclofenamate.

Materials and methods.Non-pregnant female New Zealand white rabbits weighing 1.7-3.5 kg were used in this study. Surgery was performed under Nembutal (Abbott Labs) sedation supplemented by local xylocaine (Astra Pharm.). A left ventricular catheter (i.d. 0.0288 mm) was placed via the left carotid artery and a second polyvinyl catheter was inserted 8-10 cm into the left femoral artery. The femoral catheter was then led to the neck incision via a subcutaneous tunnel. The catheters were secured to a packet made of surgical tape and attached to the rabbit's neck. Experiments were performed the following day with the awake animal resting quietly in a restraining cage.

The mean arterial blood pressure of the rabbit was monitored with a Statham P23Db transducer attached to the femoral catheter. Records were made with an R411 Beckman recorder with an EO- 18 oscilloscope display.

Blood flows were determined by the left ventricular injection of 15 micron microspheres (3M Co., New En land Nuclear) labelled with either ^l09Gd, ¹¹³Sn, ⁸⁵Sr or ⁴⁶Sc.

Soon after birth the lumens of the ductus arteriosus (DA) and umbilical artery (UA) are obliterated. It has been suggested that oxygen toxicity, resulting from an increased oxygen tension, is the cause of this destruction with superoxide radicals and hydroxyl radicals being implicated as mediators. A deficiency of superoxide dismutase (SOD) in these tissues was hypothesized as being responsible for an increase in the levels of superoxide and hydroxyl radicals. SOD levels were determined enzymatically and immunochemically in four tissues obtained from thirteen bovine fetuses. SOD levels in the DA and UA were found by both assays to be statistically significantly lower than that found in such permanent vessels as the pulmonary artery and thoracic aorta. These data are in support of the hypothesis that a lower level of SOD in the ductus arteriosus and umbilical artery may contribute to the rapid deterioration of these tissues upon exposure to greatly increased oxygen tensions.

The kind assistance of Iowa Beef Processors of Dakota City, Nebraska in obtaining calf fetuses is acknowledged. The technical assistance of two fellow medical students, Curt Bucholz and Ron Thune, and of an undergraduate student, Mark Martin, is appreciated. Supported by General Research Support Grant from the National Institutes of Health (USPHS 01 RR 05421-14). Frank O. Brady is a Research Career Development Awardee of the National Institute of Environmental Health Sciences, NIH (ES 00022).

MHV(PRI) virus produced a non-fatal immunizing infection in adult C₃H mice over a greater than 6.0 log₁₀ unit range but a uniformly fatal infection in adult Princeton (PRI) mice. Neonatally thymectomized 4-6 week old C₃H mice died by day 10 after inoculation with MHV(PRI). Intact and thymectomized C₃H mice had comparable virus titers in their livers until day 7 postinfection after which time virus was undetectable in intact C₃H mice but remained at high titers in thymectomized C₃H mice. The liver pathology was similar in both groups until day 6 post infection after which time resolving lesions were seen in livers of intact C₃H mice whereas thymectomized C₃H mice developed fulminant fatal hepatitis. In in vitro tests, the macrophages of the thymectomized C₃H mice did not support growth of MHV(PRI) virus to any greater extent than the macrophages of nonthymectomized C₃H mice.

Although infection with MHV(PRI) was fatal for both PRI and thymectomized C₃H mice, the course of infection was much more rapid in PRI mice. C₃Hss mice which are congenic with C₃H mice but have macrophages which support growth of MHV(PRI) responded to MHV(PRI) infection with a rapidly fatal illness in the same way as PRI mice. These data suggest that macrophages resistant to viral multiplication and intact thymic function are both necessary for resistance to the lethal effects of MHV(PRI) virus.

This research was supported in part by National Science Foundation Grant No. GB 31479.

Thymidine kinase and DNA polymerase activities were significantly (P < 0.05 and P < 0.01, respectively) lower in 9, 10, 11, and 12-day embryos taken from dams fed a zinc deficient diet than in those from ad libitum fed and restricted intake controls. An additional finding was that of increased activity of both thymidine kinase and DNA polymerase with increasing age of embryos. As previously found with thymidine kinase, addition of zinc and other divalent metal ions in vitro had little effect on restoration of DNA polymerase activity from zinc deficient extracts when added at concentrations of 0.01 and 0.05 mM. When added at a level of 0.2 mM, zinc, but not other metal ions, had an inhibitory effect on DNA polymerase activity. These findings support the hypothesis that the teratogenic effects of zinc deficiency are associated with the enzymes involved in DNA synthesis.

This research was supported in part by NIH Research Grant No. HD-01743 from the National Institute of Child Health and Human Development.

A diet supplemented 5% with L-histidine caused a 100% increase in the incorporation of [2-¹⁴C] acetate or [1-¹⁴C] octanoate into cholesterol in liver slices of weanling rats after four days of feeding. The incorporation of the labeled substrates into triglycerides decreased 38%. The hepatic DNA-to-protein ratio decreased 19% with histidine feeding, suggesting an increase in hepatocyte size.

We wish to thank Dr. Burr Eichelman for his help in the preparation of this manuscript.

Cholera toxin (CT) reduces tubular reabsorption of Na, Cl, Ca, Mg and P most probably through stimulation of a renal adenylate cyclase-cyclic AMP system, and it is possible that an increased production of nephrogenous cyclic AMP during extracellular fluid volume expansion may be partly responsible for the observed natriuresis. In order to further evaluate the role of renal cyclic AMP in renal tubular transport, we studied the effect of CT on glucose (TRG) and bicarbonate reabsorption (TRHCO₃).

During the period of maximal effect of CT on tubular transport (100-140 min of CT infusion into one renal artery) both the TRG and TRHCO₃ were lower in the infused kidney than in the contralateral noninfused kidney; TRG as mg per 100 ml GFR was 254 ± 32.7 vs 363 ± 43.5 (P < .01), and TRHCO₃ as mEq per 100 ml GFR was 2.09 ± 0.06 vs 2.53 ± 0.06 (P < .01). The data indicate that CT suppresses glucose and bicarbonate reabsorption together with that of sodium and as such assign to role for renal cyclic AMP in the regulation of the tubular transport of these substances.

The authors wish to thank Mr. Barry Gammel and Mrs. Verginia Barbarian for their technical assistance, and Ms. Melinda Ayers, Ms. Jamie Jimenez, Ms. Alice Moomjean and Ms. Alberta Ward for their secretarial assistance.

The sialic acid of human gelfiltered platelets was studied before and after ADP-induced shape change. Neuraminidase cleaved 47% of the total sialic acid from both discoid control platelets and platelets that had become spiny spheres after treatment with 5 μM ADP.

We are grateful to the following colleagues for materials used in these experiments: Thomas H. Finlay, Ph.D., for the radiolabeled TAMe, Joel U. Harris, Ph.D., for the radiolabeled fibrinogen, Henriette Lackner, M. D., for the connective tissue suspension, and John Fenton, II, Ph.D. for the purified human thrombin.

A diet supplemented 5% with L-histidine induces hypercholesterolemia in rats. To examine the mechanism involved, L-histidine was added to either a chow or fat-free diet and fed to rats for 18 days. After 2 days of fasting, the rats were refed the same diet for three days. There was a ninefold increase in the incorporation of [¹⁴C] acetate into the nonsaponifiable fraction in the 5,000g hepatic fraction of histidine-supplemented chow-fed rats compared to controls. The increase in the incorporation of the labeled substrate into the digitonin-precipitable fraction was seven- to eightfold. The incorporation of [¹⁴C]mevalonate was increased by sevenfold in both the nonsaponifiable and digitonin-precipitable fractions. Longterm histidine supplementation to fat-free diet did not affect the incorporation of either [¹⁴C] acetate or [¹⁴C] mevalonate into these fractions.

We wish to thank Ms. Cynthia Birch for her technical assistance.

C-st phage which governs production of type C botulinum toxin was mixed at 4° with cells of C. botulinum type C and D cultures and nontoxigenics derived from them. The phage adsorbed to all three cultures producing type C toxin, the one type D toxin producer, 2 of 4 nontoxigenics from type C parents and the three nontoxigenics originating from type D toxin producers. The phage adsorbed to some cultures without converting to toxigenicity. The two nontoxigenic which could be converted to toxigenicity differed in degrees of phage adsorption and conversion rates.

Research was supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, by NIH Grant No. FD00712, and contributions from food companies.

We pre- and posttreated SWR/ J mice given 90 mg/kg of DEN with goat anti RadLV and AT 124 IgGs and studied their effects on the induction and latency of lung tumors. The results of these experiments tend to indicate a role of MuLVs in the etiology of the chemically induced lung tumors of SWR/J mice. The rate of tumor occurrence was greatly reduced in IgG treated mice and their survival time was significantly prolonged over nontreated mice. These findings require consideration of both ecotropic and xenotropic virus classes or their structural protein as cofactors in the chemically induced lung carcinogenesis process. Similar conclusions were drawn previously by others in an in vitro chemical transformation system (5).

The cause of hypoglycemia induced by endotoxin in BCG infected mice was investigated. The major abnormality, known to be defective gluconeogenesis, was studied to determine whether a specific point in the gluconeogenic pathway is involved or whether the derangement is more general. The inability of endotoxin poisoned mice to synthesize glucose from glycerol and fructose in addition to pyruvate indicated that the entire pathway was in disarray. The in vivo oxidation of glucose, glycerol and palmitate to CO₂ was reduced, indicating that enhanced aerobic oxidation was not responsible for the hypoglycemia. This decrease in substrate oxidation also suggests that impaired gluconeogenesis may be due to decreased energy available to maintain the gluconeogenic pathway. Pharmacologic doses of glucocorticoids were protective in endotoxin poisoned BCG infected mice. The rate of development of hypoglycemia was rapidly lessened, and mortality reduced. The data suggest that steroids confer protection by preventing or interfering with some of the toxic effects of endotoxin or perhaps by activating glyconeogenic enzymes. It is unlikely that glucocorticoid mediated enzyme induction plays an anti-endotoxin role in this model.

Human granulocyte mobility under various conditions of chemotactic stimulus was studied using the agarose plate method. Enhanced mobility was observed when granulocytes were incubated in the agarose plate containing chemotactic factor generated from E. coli. A dose response type relationship was observed between the degree of enhanced mobility and the concentrations of chemotactic factor in a range of less than 10%. The rate of mobility was rapid up to 3 hr, after which time it was very slow. Preincubation of granulocytes with chemotactic factor of various concentrations did not have any influence on granulocyte mobility assayed after preincubation. The degree of mobility tends to be determined by the final concentration of chemotactic factor coming in contact with granulocytes. Thus granulocytes under a negative concentration gradient also showed an enhanced mobility. On the basis of these findings, we propose the hypothesis that the accumulation of granulocytes at the site of inflammation can be in part explained by chemokinesis, i.e. enhanced random mobility.

Hypophysectomy alters the normal diurnal feeding patterns of rats but on the average the hypophysectomized rats still consume the greatest percentage of their food during the dark phase. Compared to controls, hypophysectomized rats eat a similiar number of meals each day, however, the amount of food consumed and the duration of the meals are reduced. The pituitary gland seems to be one of the factors involved in sustaining the natural diurnal feeding rhythm in rats.

The authors wish to thank Drs. Roger and Leung for the use of the food intake monitors, and we express our appreciation for the expert technical assistance of C. M. Friend, and to S. Turley for typing the manuscript.

Mice which are normally resistant to infection with Wesselsbron (WBV) virus became rapidly susceptible to disease due to this agent after being placed on protein-depletion diet. After ip inoculation large amounts of virus appeared in the circulation followed by fatal encephalitis. In normally fed mice only small amounts of virus could be detected in blood and no disease developed. This suggested that local defense mechanisms which normally restrict the extent of infection was sensitive to the early effects of protein-calorie malnutrition. That this was due at least in part to impaired antiviral function of macrophage under these conditions was confirmed by in vitro macrophage studies. Over the course of 24 hr infectious WBV disappeared after inoculation into cultures of normal macrophages whereas infectivity persisted at high titers in macrophages from protein-depleted mice.

This work was supported by a grant from the Rockefeller Foundation.

The effect of heparin on the growth of four cell types cultivated in vitro has been investigated. The results suggest that heparin appears to have some growth promoting effects on prepuce cells, while it showed little effect on the growth of Novikoff hepatoma, monkey kidney and baby hamster kidney cells. Heparin reversed the inhibitory effect of prednisolone-21-sodium-succinate on the growth of prepuce and baby hamster kidney cells.

The authors thank Gregg Jorgenson and Chris Bjornson for their excellent techincal assistance. The opinions and statements contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the Navy Department of the Naval Service at large.

The kinetics of activation of the antiviral state by virus induced interferon and by mitogen-induced immune interferon have been studied comparatively. It has been found that both human and murine virus-induced interferons are able to activate the antiviral state after a brief (minutes) contact with the cells. In contrast, several hours were required for both human and mouse immune interferons to induce a comparable level of antiviral resistance. Experiments measuring the binding of the two interferons to cells showed that there was no significant difference in the rate and degree of binding, suggesting that a different total association of interferon with cells could not account for the slower kinetics of activation by immune interferon. Additionally, the possibility that some contaminants present in the immune interferon preparation could nonspecifically interfere with the rapid induction phenomenon is not supported by the finding that the rapid kinetics of cell activation by virus-induced interferon was not modified by the presence of immune interferon. The interesting possibility which remains is that the two interferons may activate cells by different mechanisms.

The authors are greatly indebted to Dr. G. Georgiades and Mr. M. Langford for the generous gifts of immune interferon and to Dr. S. Baron for helpful suggestions and criticism.

An improved method permitting the synthesis of a radioactive derivative of α-amanitin from a small amount of the commercially available parent compound has been developed. The labeled derivative was used in an amatoxin competition binding assay designed to detect eukaryotic RNA polymerase B in either purified form or in crude homogenates. Both compounds are shown to compete for the same binding site and with approximately the same affinity. The competition assay proves to be both sensitive and highly selective for RNA polymerase B and provides a new, direct method for studying the enzyme-amanitin interaction over a much broader range of concentration than previously reported.

We greatly appreciate the assistance of Ms. Aphia Abdou in preparation of illustrations, Ms. Donna Chambers for secretarial assistance, and Drs. John A. Armstrong, Patricia A. Craven and Mary Edmonds for critically reviewing the manuscript. This work was supported through the Medical Research Service of the U. S. Veterans Administration.

Two exometabolites have been demonstrated to accumulate in protein free culture medium in which log phase promastigotes of L. donovani are metabolizing. These molecules demonstrate gel filtration characteristics suggesting a molecular weight in the range of 800-1900. The ultraviolet absorption spectra of the exometabolites suggest the presence of peptide bonds with tyrosine present in one and tryptophan in the other. Sugar was demonstrated to be associated with both Fractions A and B, suggesting the exometabolites are glycopeptides. The exometabolite in Fraction B did not react with specific antibody to form precipitates unless it was in combination with serum protein. The data strongly suggest that the exometabolite conjugates with protein forming a multivalent entity.

Cultured human colon mucosa was found to metabolize both acyclic and cyclic N-nitrosamines as measured by ¹⁴C-CO₂ formation and reaction of the activated moieties with cellular macromolecules. Dimethylnitrosamine and N-nitrosopyrrolidine were metabolized by explants from all patients studied. A positive correlation between binding of dimethylnitrosamine to DNA and CO₂-formation was observed. DMN alkylated DNA in both O-6 and N-7 position of guanine. However, most of the radioactivity was associated with an acid labile compound. High binding levels of N,N'-dinitrosopiperazine to protein without concomitant binding to DNA were detected. Inter-individual variation in both binding level to DNA and ability to metabolize the different N-nitrosamines was observed.

We would like to thank Drs. U. Saffiotti, G. Stoner, and T. Bowden for valuable comments, Ms. R. Schwartz for technical assistance, and Mrs. M. Bellman for secretarial assistance.

Treatment of ob/ob mice with T₄ 24 hr prior to cold exposure did not alter plasma concentrations of glucose, insulin and FFA during cold exposure although ob/ob mice remained hyperglycemic and hyperin-sulinemic when compared to nonobese mice. FFA content of and FFA release from isolated adipocytes were significantly elevated in T₄ -treated obese mice after cold stress as compared to untreated obese mice. T₄ treatment also produced a marked increase in epinephrine-stimulated FFA release from fat cells of obese mice in vitro.

These results indicate that correction of the hypothyroid status of ob/ob mice with pharmacological doses of T₄ improved the in vitro lipolytic response of fat cells, but did not alter the circulating concentrations of important energy sources for thermogenesis in vivo.

The technical assistance of Ms. Teresa Pasquine is gratefully acknowledged.

Complete neural deafferentation of the MBH in 53 rats resulted in a constant vaginal diestrous smear pattern in 85% of the rats, and in this type animal very low blood LH levels and absence of episodic LH release followed ovariectomy. The remaining 15% had a constant vaginal estrous smear pattern, and most demonstrated pulsatile LH secretion following ovariectomy. Thus, afferent input to the MBH seems to be required in most rats to sustain episodic LH secretion. Administration of apomorphine, a dopamine receptor stimulator, to animals which were in constant estrus before ovariectomy, resulted in inhibition of pulsatile LH secretion, suggesting that this apomorphine-induced inhibition is a result of activation of dopamine receptors within, rather than outside, the MBH-pituitary unit.

We would like to thank Brad Garibaldi, Bob Schlegel, Veronica Lickova and Cindy Voytek for their help in these studies, and Annette Lowe and Linda Delucchi for preparation of the figures and typing the manuscript. Thanks also to Dr. G. Niswender for anti-ovine LH No. 15, Dr. H. Papkoff for highly purified ovine LH No. G3222B for iodination, Dr. J. Garcia for goat antiserum against rabbit gammaglobulin, and Dr. A. F. Parlow and the NIAMDD for the rat LH used as a reference preparation.

A Staph, aureus mutant (52A5) which is deficient in wall teichoic acid (TA) was found to be highly susceptible to lysis by leukocyte extracts (ENZ) and by myeloperoxidase (MPO) when harvested from the stationary phase of growth, On the other hand, a staphylococcus mutant, which is deficient in N-acetyl glucosamine in its TA (52A2), the parent strain SH and a protein A rich strain Cowen I, could be lysed by the leukocyte factors only when harvested from the logarithmic phase of growth.

The lysis of all the bacterial strains by ENZ or by MPO was strongly inhibited by lipoteichoic acid (LTA) derived either from staphylococci or from streptococci. On the other hand, deacylated LTA, TA, LPS, cytoplasmic or cell wall components derived from streptococci had no inhibitory effect on bacteriolysis. It is concluded that TA may be important in the protection of old bacterial cells against degradation by leukocyte factors, and that LTA may be involved in the control of autolytic enzymes in staphylococci. The role of MPO in bacteriolysis is also discussed.

A relationship between polybrominated biphenyl, Firemaster FF-1 (FF-1), in the diet, and eggs, as monitored by hexahromobiphenyl (6-BB), and embryo toxicity, as measured by hatchability, were examined. The minimum dietary level of FF-1 for an effect on hatchability was estimated at 42 ppm, which produced an egg residue estimated at 65.9 ppm 6-BB. Generally, as FF-1 in the diet increased, egg residues increased and hatchability decreased. Regression equations were established for these relationships. After withdrawal of FF-1 in the diet, hatchability returned to normal when FF-1 treatments had been <625 ppm. Over a range of 30-85 ppm 6-BB in eggs there was poor correlation to an effect on hatchability. These latter data were discussed in terms that the 6-BB peak may not be a definitive approach to assess FF-1 toxicity.

The authors express their appreciation for assistance in this project to Mr. Sulo Hulkonen, Mr. Edward Kowaleski, Mr. Dennis Dodson, and Ms. Melinda Neff.

In order to determine the physiochemical homogeneity of the human red cell, intraerythrocyte pH was simultaneously measured using the weak acid 5,5-dimethyl-oxazolidine-2,4-dione (DMO) and the weak base nicotine. If a cell is homogeneous, such measurements will yield the same result. If a cell is heterogeneous, the DMO reading will be closer to the highest pH in the cell system, while the nicotine will read closer to the lowest pH. The results show no significant difference between the intracellular pH obtained by either of these methods (average by DMO = 7.10, by nicotine = 7.06 at an average external pH of 7.33). We conclude that the human erythrocyte is physiochemically homogeneous.

Protein deficiency in rats results in decreased ability to produce erythropoietin after hypoxic stimulation. This defect can be reversed by a single protein feeding at the time of exposure to hypoxia. The present experiments show that feeding of methionine, leucine or cystine also corrected the defect in erythropoietin production. These amino acids may serve to signal the adequacy of protein reserves and permit the synthesis of erythropoietin. Other single amino acids had minimal or no effect.

Study has been supported by University of Illinois BRSG 7612, Veterans Administration Research Funds, funds from the American Cancer Society, Illinois Division, Leukemia Research Foundation and the Hematology Research Foundation. The authors wish to thank Mrs. Jan Rone for her technical assistance.

Ornithine decarboxyase (ODC) activity increases when cells are acutely transformed with murine sarcoma virus (MSV). Three contact inhibited or MSV transformed clones of Balb/3T3 were transformed or supertransformed by MSV or its accompanying non-transforming ‘helper’ virus (MuLV), and the relationships between ODC activity, morphology, virus production and growth rates were examined. Clones isolated from these lines were also studied. All of the virus infected lines released both MSV and MuLV. ODC activities could not be correlated with differences in growth rates. The only consistent relationship was between elevated ODC activity and acute morphological transformation, suggesting that polyamine metabolism plays a crucial role in the transformation process. With time, the elevated ODC activities returned towards baseline levels. Thus ODC activity does not appear to be a useful marker for chronic infection or transformation by type C viruses.

The authors thank John Minna, Harold Stull, Herbert Oie, Edward Russelll, Patricia Hefel, and Theresa Gregorio for suggestions and assistance.

The dietary induction of liver G6PD was found to be markedly impaired in the acute hepatic injury of rat caused by thioacetamide intoxication. The level of cyclic AMP in the injured liver was increased and could not be reduced by glucose-containing diets. The results indicated that the suppressed dietary inducibility of G6PD in hepatic injury is accounted for at least by the dietary unresponsive increase in cyclic AMP level in the injured liver.

During the first week of postnatal life, there were significant changes in red cell volume, plasma volume, and venous and circulatory hematocrits in both the beagle and the pig. In beagle pups the mean red cell volume decreased between 2.5 and 8.5 hr after birth, then increased at 16.5 hr, with a further increase on day 1. Between days 2 and 7, red cell volume decreased. There was evidence of a release of red cells into the circulation from red cell reservoirs. In the newborn pig, red cell volume decreased between days 0 and 2, but was not significantly different on day 7 from day 2. In the beagle the mean plasma volume did not change during the first 12 hr following birth; it increased between 12 and 24 hr after birth and remained unchanged through day 7. In the pig, plasma volume decreased between day 0 and day 1, increased on day 2, and was not significantly different on day 7 from day 2. The increase in plasma volume was the result of an increase in plasma protein, which caused a redistribution of fluid among the various fluid compartments. In the beagle, blood volume decreased between 2.5 hr and 8.5 hr, increased at 16.5 hr with a further increase on day 1, then decreased on day 2, with no further change on day 7. The blood volume in the pig decreased progressively between day 0 and day 7. The changes in venous and circulatory hematocrits for both the beagle and pig reflected those of red cell and plasma volumes throughout the first week of life. The BVR_cells did not change significantly, indicating that there was no shift in the distribution of red cells and plasma in the circulation over this 7-day period.

Time course of 17-β estradiol and luteinizing hormone-releasing hormone effect on LH release was studied using bovine pituitary cells on day 5 of culture. LHRH at concentrations of .1, 1, 10 and 100 ng/ml increased LH in medium linearly with increasing log concentration of LHRH when present for .75, 1.5, 3, 6 and 24 hr and the percent increase over controls was same at each time period. In addition, estradiol (present for 6, 12 or 24 hr) at .5, 5, and 50 ng/ml also increased LH release linearly both in the presence or absence of LHRH. We conclude that the stimulatory effect of LHRH on LH release from bovine pituitary is consistant over 24 hr and the stimulatory effect of E2 on both basal and LHRH induced LH release may be mediaed at least in part directly on the pituitary.

The authors acknowledge Dr. R. R. Neitzel and L. T. Chapin for valuable assistance with computer programming and P. Harkins and C. Wallace for technical help.

[d-Phe², Phe³, d-Phe⁶]-LH-RH, a potent antagonist of LH-RH, was injected during the different stages of the estrous cycle in rats at a dose of 1.5 mg/rat. When it was administered at noon or proestrus, a 100% blockade was observed. This decreased to 33% and 17% when the analogue was injected at 9 am on proestrus and diestrus 2, respectively. No blockade of ovulation was observed after the injection of the analogue on diestrus 1 or on the previous estrus. The sequential administration of the analogue twice daily on E, D1 and D2, brought about almost complete suppression of LH surge on proestrus and an 86% blockade of ovulation without altering the cyclic vaginal smear pattern. In this case, serum levels of estradiol were not modified but progesterone levels were significantly lower on proestrus and higher on diestrus 1 in the analogue treated group as compared to control rats. This higher level of progesterone on diestrus 1 might account in part for the inhibition of the LH-surge and blockade of ovulation by the inhibitory analogues of LH-RH.

We thank. Mrs. J. Gauthier and Mrs. J. Wade for their valuable technical assistance; Dr. G. Niswender, Dr. Ward and NIAMDD-Rat-Pituitary Hormone Program for the gifts of materials used in radioimmunoassays.